Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

"Online First" included
Approved and published publications
Only approved publications

41681 Publications

Microorganisms for biological remediation of uranium contaminated sites – a microscopic and spectroscopic approach

Krawczyk-Bärsch, E.; Gerber, U.; Müller, K.; Rossberg, A.; Merroun, M. L.

Abstract

Environmental pollution by metals and radionuclides is one of the biggest challenges. For remediation of contaminated environments after activities such as uranium mining and uranium processing, microorganisms could be important due to their ability to immobilize radionuclides and heavy metals. Bioremediation strategies can be improved by a better understanding of binding mechanisms on the molecular level. Therefore, we applied uranium interaction experiments with Acidovorax facilis, an aerobic, Gram-negative Betaproteobacteria, which is commonly found in soils but also in the mine water of uranium mines. For spectroscopic and microscopic studies, kinetic uranium(VI) sorption experiments were performed under aerobic conditions with an Acidovorax facilis strain by adjusting an initial uranium(VI) concentration to 0.1 mM to the batch culture at a neutral pH range. A high-resolution image of the cellular localization of uranium by A. facilis was achieved by using electron microscopy (STEM/HAADF). The elemental distribution analysis of phosphorus and uranium clearly indicates that uranium is entirely present in the cell membrane and only with minor amounts in the poly-phosphate granules (PPGs) during the first hour of incubation (s. Fig.1). By cryo-Time-resolved laser-induced fluorescence spectroscopy (cryo-TRLFS) studies it was shown that the local coordination of uranium species associated with the cells depends upon time contact. Uranium is bound mainly to phosphate groups of lipopolysaccharide [1] at the outer membrane within the first hour. And, that both, phosphoryl and carboxyl functionality groups of LPS and peptidoglycan of A. facilis cells may effectuate the removal of high uranium amounts from solution at 24–48 h of incubation. These results support those obtained by Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS), where a relative short average U-Oeq bond length of 2.35 Å was observed for the uranium(VI) interaction with lipopolysaccharide indicating a binding of the uranium(VI) via organic phosphate groups in a monodentate fashion. Our results clearly demonstrate that A. facilis may play an important role in predicting the transport behaviour of uranium in the environment and that the results will contribute to the improvement of bioremediation methods of uranium-contaminated sites.

Keywords: uranium; sorption; Acidovorax facilis; STEM; EXAFS

Involved research facilities

Related publications

  • Lecture (Conference)
    3rd International Caparica Conference on Polutant Toxic Ions and Molecules, 04.-07.11.2019, Costa da Caparica, Portugal

Permalink: https://www.hzdr.de/publications/Publ-29833


Imaging artefacts during simultaneous in-beam MR imaging and proton pencil beam irradiation

Gantz, S.; Hietschold, V.; Schneider, S.; Hoffmann, A. L.

Abstract

The targeting precision of proton therapy is expected to benefit from real-time MRI guidance. We developed a setup of a first prototype in-beam MRI scanner with a proton pencil beam scanning nozzle. Dipole magnets in the nozzle used for beam steering produce time-dependent magnetic fringe fields that may interfere with the MR image acquisition. In this study, we show that vertical beam steering shows no degradation of the MR image quality, whereas horizontal beam steering introduces severe ghosting artefacts in phase encoding direction. The origin of these artefacts is unraveled and strategies to eliminate or correct these artefacts are proposed.

  • Contribution to proceedings
    ISMRM 2020, 18.04.2020, Sydney, Australia

Permalink: https://www.hzdr.de/publications/Publ-29832


Superconductivity of Organic Charge-Transfer Salts

Wosnitza, J.

Abstract

Forty years after the discovery of the first organic superconductor, the nature of the superconducting state in these materials is still not fully understood. Here, I present an overview on the historical developments and current knowledge on this topic for the quasi-one- and quasi-two-dimensional (2D) organic charge-transfer salts. Thereby, I focus on the prototype materials based on the donor molecules tetramethyltetraselenafulvalene (TMTSF) and bisethylenedithio-tetrathiafulvalene (BEDT-TTF or ET for short). 2D organic superconductors based on the latter molecule are found to show Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) states at high magnetic fields and low temperatures. Thermodynamic and nuclear magnetic resonance data give robust evidence for the existence of this FFLO state with modulated order parameter.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29831


A numerical simulator for modeling the coupling processes of subsurface fluid flow and reactive transport processes in fractured carbonate rocks

Yuan, T.; Wei, C.; Zhang, C.-S.; Qin, G.

Abstract

Water–rock interactions can alter rock properties through chemical reactions during subsurface transport processes like geological CO2 sequestration (GCS), matrix acidizing, and waterflooding in carbonate formations. Dynamic changes in rock properties cause a failure of waterflooding and GCS and could also dramatically affect the efficiency of the acidizing. Efficient numerical simulations are thus essential to the optimized design of those subsurface processes. In this paper, we develop a three-dimensional (3D) numerical model for simulating the coupled processes of fluid flow and chemical reactions in fractured carbonate formations. In the proposed model, we employ the Stokes–Brinkman equation for momentum balance, which is a single-domain formulation for modeling fluid flow in fractured porous media. We then couple the Stokes–Brinkman equation with reactive-transport equations. The model can be formulated to describe linear as well as radial flow. We employ a decoupling procedure that sequentially solves the Stokes–Brinkman equation and the reactive transport equations. Numerical experiments show that the proposed method can model the coupled processes of fluid flow, solute transport, chemical reactions, and alterations of rock properties in both linear and radial flow scenarios. The rock heterogeneity and the mineral volume fractions are two important factors that significantly affect the structure of conductive channels.

Keywords: reactive-transport; fracture evolution; mineral dissolution; fractured carbonate formations

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29830


Novel 2-fluoropyridinyl analogs of FACH and biological evaluation of one potential radioligand for imaging of monocarboxylate transporters (MCTs) with PET

Sadeghzadeh, M.; Wenzel, B.; Gündel, D.; Deuther-Conrad, W.; Toussaint, M.; Moldovan, R.-P.; Teodoro, R.; Jonnalagadda, S.; Jonnalagadda, S. K.; Mereddy, V. R.; Drewes, L. R.; Brust, P.

Abstract

Objective: MCT1-4 are involved in several diseases, particularly in cancer. [18F]FACH has recently been developed as a novel MCT-targeting imaging agent (1), which could be used for monitoring MCT-based treatment approaches. With the aim to develop a similar potent radiotracer with higher brain permeability for future brain tumor studies, we designed structurally modified analogs of FACH possessing increased lipophilicity.

Methods: Two analogs of FACH (I and II) were synthesized by introduction of a 2-fluoropyridinyl moiety via Buchwald-Hartwig cross coupling reaction. Inhibition of MCT1 was measured by [14C]lactate uptake assay using rat brain endothelial cells and analog I with higher inhibition was selected to synthesize corresponding precursor used for radiofluorination by aromatic nucleophilic substitution. LogD7.4 of [18F]I was experimentally determined in the n-octanol-PBS system. In vitro autoradiography and dynamic PET studies of [18F]I were performed in CD-1 mice.

Results: The analogs I and II showed a moderate MCT1 inhibition with IC50 values of 118 and 274 nM, respectively. [18F]I was obtained with radiochemical yields of 73±12% (n=4, non-isolated) and a high radiochemical purity of > 98%. A logD7.4 value of 0.816 was achieved for [18F]I, which was 2-fold higher than that for [18F]FACH. By in vitro autoradiography in cryosections of the mouse kidney, nearly complete displacement of [18F]I by 10-5 M CHC-Na was observed. In vivo, similar to [18F]FACH, a low uptake of [18F]I in the brain without significant washout was found with an almost constant SUV of 0.15 between 15 and 60 min p.i.

Conclusion: Despite a higher lipophilicity of [18F]I compared to [18F]FACH, the brain uptake of [18F]I was in a similar low range. However, the high and specific uptake of the new radiotracer in the kidneys suggests suitability of [18F]I for detecting MCTs’ expression in vivo.

References: (1) Sadeghzadeh M, et al. J Label Compd Radiopharm.2019; 62: 411-424.

  • Lecture (Conference) (Online presentation)
    58. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin (DGN2020), 22.-25.04.2020, Leipzig, Germany

Permalink: https://www.hzdr.de/publications/Publ-29829


Preclinical in vivo evaluation of [18]FACH in piglets: A new radiotracer for imaging of monocarboxylate transporters (MCTs)

Gündel, D.; Sadeghzadeh, M.; Wenzel, B.; Sattler, B.; Deuther-Conrad, W.; Kranz, M.; Toussaint, M.; Ludwig, F.-A.; Moldovan, R.-P.; Teodoro, R.; Sabri, O.; Brust, P.

Abstract

Objective: Recently, we developed [18F]FACH as the first radiolabeled inhibitor of MCTs for potential tumor imaging (1). Encouraged by the very promising results in mice, showing the specific binding/transport of [18F]FACH in kidneys combined with high in vivo stability, herein we report on the biological evaluation of this radiotracer in piglets.

Methods: Biological evaluation was performed in 6 piglets (Landrace, 19.9±3.0 kg). The blocking experiments (n=3) were conducted using sodium α-cyano-4-hydroxycinnamate (α-CHC-Na, 25 mg/kg) administered i.v. 10 min prior to tracer application. The animals were anesthesized (ketamin/midazolam) and scanned by a SIEMENS Biograph mMR PET/MRI-system up to 60 min p.i. of 295±28 MBq [18]FACH via ear vein. The reconstructed list-mode PET-data were analyzed utilizing the PMOD Software. In vivo metabolite analysis was performed using plasma isolated from arterial blood samples (5, 15, 30, 45 and 60 min) and samples of homogenized kidney by semi-preparative radio-HPLC after deproteinization by ACN/H2O (9:1).

Results: In contrast to mouse, a rather fast metabolism of the radiotracer was observed in piglet. Five and 30 minutes after injection, the intact tracer was found to represent 50±13% and 12±6% of total plasma activity, respectively. Metabolite analysis revealed 48% of intact tracer in kidney cortex at 60 min p.i. Despite the fast metabolism, the PET scan results showed comparable selective kidney uptake of [18F]FACH in piglets as in mice. The blocking experiments revealed a reduction of this uptake to about 72% after pre-injection of α-CHC-Na.

Conclusion: The high kidney uptake of [18F]FACH obtained in both mice and piglets together with high inhibition by α-CHC-Na, specific inhibitor of MCT, provide evidence that the new MCT-targeting radiotracer could be proven in ongoing studies to be useful for imaging of MCTs expression with PET.

  • Lecture (Conference) (Online presentation)
    58. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin (DGN2020), 22.-25.04.2020, Leipzig, Germany

Permalink: https://www.hzdr.de/publications/Publ-29827


X-ray spectrometer simulation code with a detailed support of mosaic crystals

Smid, M.; Pan, X.; Falk, K.

Abstract

We present a newly developed ray tracing code called mmpxrt, dedicated to study and design x-ray crystal optics, with a special focus on mosaic crystal spectrometers. Its main advantage over other currently available ray tracing codes is that it includes detailed and benchmarked algorithm to treat mosaic crystals, especially HOPG and HAPG (Highly Oriented / Annealed Pyrolitic Graphite). The code is dedicated primarily to study crystal spectrometers, therefore their implementation is very straightforward, and the code has mostly automatic evaluation of their performance. It can, however, be used universally to study other crystal instruments, like monochromators, mirrors, and analyzers.
The code is publicly available, written in Python3 and is distributed as a Python library with test cases included.

Keywords: mossaic crystal; x-ray spectroscopy; raytracing; python

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29826


Population balance modelling of isothermal and non-isothermal bubbly flows

Liao, Y.

Abstract

In bubbly flows, bubble size may vary with time and space as the result of coalescence and breakage, shrinkage and growth due to mass and/or heat transfer as well as other dynamic and transport processes occurring at the interface. One major task and challenge in modelling of bubbly flows is to reconstruct these processes and trace the change of local bubble size, since it is crucial in affecting the rate of all interfacial transfers. The population balance equation provides the basis for the description of the dynamics of particulate systems. It has become of great interest in a number of scientific disciplines or application fields. Different forms of the population balance models have been presented, and they all allow one to take into account above bubble size change mechanisms through so-called kernels. Nevertheless, continuous efforts are needed in developing, calibrating and validating the kernels. In addition, reliable and efficient solution of the population balance equation is not trivial. The presentation will focus on the class method of population balance modelling, its coupling with the two-fluid-model and application to adiabatic air-water, condensing and evaporating steam-water bubbly flows as well as recent progresses in developing coalescence and breakup kernels.

Keywords: Bubbly flow; Coalescence and breakup; CFD-PBM coupled method; Phase change; Population balance model

Involved research facilities

  • TOPFLOW Facility
  • Invited lecture (Conferences)
    NSFC-DEG International Workshop on Three-Phase Flow Modelling and Simulation, 23.-25.10.2019, Ningbo, China

Permalink: https://www.hzdr.de/publications/Publ-29825


The intensive DT neutron generator of TU Dresden

Klix, A.; Döring, T.; Domula, A.; Zuber, K.

Abstract

TU Dresden operates an accelerator-based intensive DT neutron generator. Experimental activities comprise investigation into material activation and decay, neutron and photon transport in matter and R&D work on radiation detectors for harsh environments. The intense DT neutron generator is capable to produce a maximum of 1012 n/s. The neutron source is a solid-type water-cooled tritium target based on a titanium matrix on a copper carrier. The neutron yield at a typical deuteron beam current of 1 mA is of the order of 1011 n/s in 4Π. A pneumatic sample transport system is available for short-time irradiations and connected to wo high-purity germanium detector spectrometers for the measurement of induced activities. The overall design of the experimental hall with the neutron generator allows a flexible setup of experiments including the possibility of investigating larger structures and cooled samples or samples at high temperatures.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29823


ATM controls DNA repair and mitochondria transfer between neighboring cells

Jin, S.; Cordes, N.

Abstract

Intercellular communication is essential for multicellular tissue vitality and homeostasis. We show that healthy cells message protective signals through direct cell–cell connections to adjacent DNA–damaged cells in a microtubule–dependent manner. In DNA–damaged cells, mitochondria restoration is facilitated by fusion with undamaged mitochondria from healthy cells and their DNA damage repair is optimized in presence of healthy cells. Both, mitochondria transfer and intercellular signaling for an enhanced DNA damage response are critically regulated by the activity of the DNA repair protein ataxia telangiectasia mutated (ATM). These healthy–to–damaged prosurvival processes sustain normal tissue integrity and may be exploitable for overcoming resistance to therapy in diseases such as cancer.

Keywords: Cell–cell communication; genotoxic stress; mitochondria exchange; DNA damage repair; ataxia telangiectasia mutated (ATM)

Permalink: https://www.hzdr.de/publications/Publ-29822


Studies on Flat Sandwich-type Self-Powered Detectors for Flux Measurements in ITER Test Blanket Modules

Raj, P.; Angelone, M.; Döring, T.; Eberhardt, K.; Fischer, U.; Klix, A.; Schwengner, R.

Abstract

Neutron and gamma flux measurements in designated positions in the test blanket modules (TBM) of ITER will be important tasks during ITER's campaigns. As part of the ongoing task on development of nuclear instrumentation for application in European ITER TBMs, experimental investigations on self-powered detectors (SPD) are undertaken. This paper reports the findings of neutron and photon irradiation tests performed with a test SPD in flat sandwich-like geometry. Whereas both neutrons and gammas can be detected with appropriate optimization of geometries, materials and sizes of the components, the present sandwich-like design is more sensitive to gammas than 14 MeV neutrons. Range of SPD current signals achievable under TBM conditions are predicted based on the SPD sensitivities measured in this work.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29821


Comparison between Silicon-Carbide and diamond for fast neutron detection at room temperature

Obraztsova, O.; Ottaviani, L.; Klix, A.; Döring, T.; Palais, O.; Lyoussi, A.

Abstract

Neutron radiation detector for nuclear reactor applications plays an important role in getting information about the actual neutron yield and reactor environment. Such detector must be able to operate at high temperature (up to 600° C) and high neutron flux levels. It is worth nothing that a detector for industrial environment applications must have fast and stable response over considerable long period of use as well as high energy resolution. Silicon Carbide is one of the most attractive materials for neutron detection. Thanks to its outstanding properties, such as high displacement threshold energy (20-35 eV), wide band gap energy (3.27 eV) and high thermal conductivity (4.9 W/cm·K), SiC can operate in harsh environment (high temperature, high pressure and high radiation level) without additional cooling system. Our previous analyses reveal that SiC detectors, under irradiation and at elevated temperature, respond to neutrons showing consistent counting rates as function of external reverse bias voltages and radiation intensity. The counting-rate of the thermal neutron-induced peak increases with the area of the detector, and appears to be linear with respect to the reactor power. Diamond is another semi-conductor considered as one of most promising materials for radiation detection. Diamond possesses several advantages in comparison to other semiconductors such as a wider band gap (5.5 eV), higher threshold displacement energy (40-50 eV) and thermal conductivity (22 W/cm·K), which leads to low leakage current values and make it more radiation resistant that its competitors. A comparison is proposed between these two semiconductors for the ability and efficiency to detect fast neutrons. For this purpose the deuterium-tritium neutron generator of Technical University of Dresden with 14 MeV neutron output of 1010 n·s-1 is used. In the present work, we interpret the first measurements and results with both 4H-SiC and chemical vapor deposition (CVD) diamond detectors irradiated with 14 MeV neutrons at room temperature.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29820


Comparing the Response of a SiC and a sCVD Diamond Detectors to 14-MeV Neutron Radiation

Obraztsova, O.; Ottaviani, L.; Klix, A.; Döring, T.; Palais, O.; Lyoussi, A.

Abstract

Radiation detectors based on wide-bandgap semiconductors have received considerable attention in many applications such as the experiments in material testing reactors, high energy particle physics experiments, or fusion facilities for plasma diagnostics. In this paper, we compared a 4H-silicon-carbide (SiC)-based detector with a single crystal chemical vapor deposited (sCVD) diamond-based detector for 14-MeV neutron detection. For this purpose, the deuterium- tritium neutron generator of Technical University of Dresden with 14-MeV neutron output up to 10 11 n/sin 4π has been used. In this paper, we interpret the results of our first measurements with both 4H-SiC and sCVD diamond detectors at low neutron flux of 9.4 × 10 6 n/(cm 2 · s) and at room temperature.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29819


Neutron flux measurements on a mock-up of a storage cask for high-level nuclear waste using 2.5 MeV neutrons

Saurí Suárez, H.; Becker, F.; Klix, A.; Pang, B.; Döring, T.

Abstract

To store and dispose spent nuclear fuel, shielding casks are employed to reduce the emitted radiation. To evaluate the exposure of employees handling such casks, Monte Carlo radiation transport codes can be employed. Nevertheless, to assess the reliability of these codes and nuclear data, experimental checks are required. In this study, a neutron generator (NG) producing neutrons of 2.5 MeV was employed to simulate neutrons produced in spent nuclear fuel. Different configurations of shielding layers of steel and polyethylene were positioned between the target of the NG and a NE-213 detector. The results of the measurements of neutron and γ radiation and the corresponding simulations with the code MCNP6 are presented. Details of the experimental set-up as well as neutron and photon flux spectra are provided as reference points for such NG investigations with shielding structures.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29818


Radiosynthesis and Biological Investigation of a Novel Fluorine-18 Labeled Benzoimidazotriazine- based Radioligand for Imaging of Phosphodiesterase 2A with Positron Emission Tomography

Ritawidya, R.; Wenzel, B.; Teodoro, R.; Toussaint, M.; Kranz, M.; Deuther-Conrad, W.; Dukic-Stefanovic, S.; Ludwig, F.-A.; Scheunemann, M.; Brust, P.

Abstract

A specific radioligand for imaging of cyclic nucleotide phosphodiesterase 2A (PDE2A) via positron emission tomography (PET) would be helpful for research on the physiology and disease-related changes in the expression of this enzyme in the brain. In this report, the radiosynthesis of a novel PDE2A radioligand and the subsequent biological evaluation is described. Our prospective compound 1-(2-chloro-5-methoxy phenyl)-8-(2-fluoropyridin-4-yl)-3- methylbenzo[e]imidazo[5,1-c][1,2,4]triazine, BIT1 (IC50 PDE2A = 3.33 nM; 16-fold selectivity over PDE10A) was fluorine-18 labeled via aromatic nucleophilic substitution of the corresponding nitro precursor using the K[18F]F‐K2.2.2‐carbonate complex system. The new radioligand [18F]BIT1 was obtained with a high radiochemical yield (54 ± 2%, n = 3), a high radiochemical purity (≥99%) and high molar activities (155‐175 GBq/μmol, n = 3). In vitro autoradiography on pig brain cryosections exhibited an heterogenous spatial distribution of [18F]BIT1 corresponding to the known pattern of expression of PDE2A. The investigation of in vivo metabolism of [18F]BIT1 in mouse revealed a sufficient metabolic stability. PET studies in mouse exhibited a moderate brain uptake of [18F]BIT1 with a maximum standardized uptake value of ~0.7 at 5 minutes p.i. However, in vivo blocking studies revealed a non-target specific binding of [18F]BIT1. Therefore, further structural modifications are needed to improve target selectivity.

Keywords: cyclic nucleotide phosphodiesterase; PDE2A radioligand; nitro-precursor; fluorine-18; in vitro autoradiography; PET imaging

Permalink: https://www.hzdr.de/publications/Publ-29817


Maximizing the benefit of limited proton therapy resources through combined proton-photon treatments

Loizeau, N.; Fabiano, S.; Papp, D.; Jakobi, A.; Bandurska-Luque, A.; Stützer, K.; Richter, C.; Unkelbach, J.

Abstract

Objective: Although rapidly growing, proton therapy (PT) is a limited resource, which is not available to all patients who may benefit from it. Here, we investigate combined proton-photon treatments as an approach to optimally use the limited PT resources and maximize the benefit of PT at a population level. As an example, we consider a clinic offering both photons and protons and a scenario, in which only limited PT slots are available per day for treating head and neck cancer (HNC) patients.
Materials and methods: We assume a fixed number of available proton slots per day and, on average, 2 new HNC patients per week, each receiving 30 fractions over 6 weeks. We designed a slot allocation model that selects, on a daily basis, those patients currently under treatment who benefit the most from a proton treatment on the respective day. The remaining patients on that day receive a photon fraction. The model is based on modern normal tissue complication probability (NTCP) models (e.g. for xerostomia [2]). This daily slot allocation strategy is compared (in terms of average NTCP values) to a threshold-based PT patient selection in which patients are selected for whole PT treatment if a slot is available at start of fractionated treatment and their ΔNTCP exceeds a threshold (5%, 10%, 15%). To simulate many patients, the doses in relevant OARs (e.g. contralateral parotid gland) are sampled from a 2D gaussian distribution (Figure 1) derived from the OAR doses of 45 HNC patients for which IMRT and IMPT plans were previously created [1] and rescaled to a standard of care prescription (1.8 Gy to PTV, 2.3 Gy to GTV).
Results: The daily slot allocation strategy leads to a higher reduction of the average NTCP values for xerostomia than the threshold-based PT patient selection as shown in Figure 2 for any number of available proton slot per day. If all patients receive only photons or only protons, the average NTCP values for xerostomia are 16.9% and 6.3%, respectively. If 3 proton slots are available per day for HNC patients, the average NTCP value for xerostomia is 12.5% for the daily slot allocation strategy and 14.0% for the threshold-based PT patient selection which would select patients with 10% ΔNTCP threshold. The NTCP benefit of 1.5% can be explained by two considerations: 1) combined proton-photon treatments make optimal use of all proton slots whereas patient selection strategies face a trade-off between leaving slots unused or blocking slots for future patients with higher benefit; 2) on the convex part of the NTCP curve, the first proton fractions delivered are the most beneficial.
Conclusion: Limited proton therapy resources can be more efficiently utilized, from a global health system perspective, with combined proton-photon treatments with daily allocation of proton slots compared to single-modality treatments with optimal patient selection.
[1] Jakobi A. et al., IJROBP, 92.5 (2015): 1165-1174 [2] Houweling A.C. et al., IJROBP, 76.4 (2010): 1259-1265

  • Lecture (Conference) (Online presentation)
    ESTRO 2020, 03.-07.04.2020, Wien, Austria

Permalink: https://www.hzdr.de/publications/Publ-29816


Inertial spin dynamics in ferromagnets

Kumar, N.; Awari, N.; Kovalev, S.; Polly, D.; Hagström, N. Z.; Arekapudi, S. S. P. K.; Semisalova, A.; Lenz, K.; Green, B. W.; Deinert, J.-C.; Ilyakov, I.; Chen, M.; Bawatna, M.; Scalera, V.; D’Aquino, M.; Serpico, C.; Hellwig, O.; Jean-Eric, W.; Gensch, M.; Bonetti, S.

Abstract

The understanding of how spins move at pico- and femtosecond time scales is the goal of much of modern research in condensed matter physics, with implications for ultrafast and more energy-efficient data storage. However, the limited comprehension of the physics behind this phenomenon has hampered the possibility of realising a commercial technology based on it. Recently, it has been suggested that inertial effects should be considered in the full description of the spin dynamics at these ultrafast time scales, but a clear observation of such effects in ferromagnets is still lacking. Here, we report the first direct experimental evidence of inertial spin dynamics in ferromagnetic thin films in the form of a nutation of the magnetisation at a frequency of approximately 0.6 THz. This allows us to evince that the angular momentum relaxation time in ferromagnets is on the order of 10 ps.

Keywords: Magnetisation; ultrafast spin dynamics; ferromagnetic thin films

Involved research facilities

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29815


Ferromagnetic resonance detection in magnetic single objects via a novel microresonator and microantenna approach

Cansever, H.; Lenz, K.; Narkowicz, R.; Kowalska, E.; Faßbender, J.; Deac, A. M.; Lindner, J.

Abstract

Ferromagnetic resonance has been commonly used as a spectroscopic technique investigating the fundamental properties of ferromagnetic materials, such as magnetization, g-factor, magnetic anisotropy and damping (relaxation) parameters [1-4].Conventionally, an FMR spectrometer is operating at a fixed microwave frequency to detect the microwave absorption of the magnetic object by sweeping an external magnetic field through the resonance. The sensitivity of this weak absorption process is typically enhanced by using a microwave bridge setup. However, for a reliable quantification of key magnetic parameters like the g-factor or spin relaxation times, the measurements should be performed within a broad range of frequencies. This is achieved by broadband FMR spectrometers which employ vector network analyzers (VNA) that detect the microwave transmission or reflection parameters of the sample [5-6]. However, neither conventional cavities nor broadband FMR spectrometers are able to detect signals of micro/nano size samples due to the tiny sample volume. To achieve optimal sensitivity for small objects, planar microresonators were introduced for electron paramagnetic resonance (EPR) experiments [7]. Microresonators have been used to investigate magnetization dynamics of magnetic object to understand uniform and spin wave modes [8], as well as the spin-Seebeck effect in magnetic tunnel junctions [9.] The microresonator approach allows producing rf magnetic fields homogeneously concentrated inside a metallic loop, thereby increasing the filling factor of the resonator. Here, we explain the novel microesonator approach in detail and introduce moreover a microantenna approach which allows to perform experiments in the range of 8-18 GHz employing a co-planar layout. We investigate magnetization dynamics within Permalloy (Ni80Fe20) wires by using both, microresonator and microantenna approach.

[1] P. E. Wigen, C.F. Kooi, M. R Shanaberger, T. R. Rosing, Phys. Rev. Lett. 9, 206, 1962.
[2] P. E. Wigen, Z. Zhang, Braz. J. Phys. 22, 267, 1992.
[3] M. Farle, “Rep. Prog. Phys. 61, 755, 1998.
[4] J. R. Fermin, A. Azevedo, F. M. Aguiar, B. Li, S. M. J. Rezende, Appl. Phys. 85, 7316, 1999.
[5] M. Vroubel, Y. Zhuang, B. Rejaei, J. N. Burghartz, J. Appl. Phys. 99, 08P506, 2006.
[6] C. Nistor, K. Sun, Z. Wang, M. Wu, C. Mathieu, M. Hadley Appl. Phys. Lett. 95, 012504, 2009.
[7] R. Narkowicz, D. Suter, I. Niemeyer, Rev. Sci. Instrum. 79, 084702, 2008.
[8] A Banholzer, R Narkowicz, C Hassel, R Meckenstock, S Stienen, O Posth, D Suter, M Farle, J Lindner, Nanotechnology, 22, 295713, 2011.
[9] H. Cansever, R. Narkowicz, K. Lenz, C. Fowley, L. Ramasubramanian, O. Yildirim, A. Niesen, T. Huebner, G. Reiss, J. Lindner, J. Fassbender, A. M. Deac, J. Phys. D: Appl. Phys. 51, 22400, 2018.

Keywords: ferromagnetic resonance; microresonator; microantenna

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    9th APMAS 2019 - International Advances in Applied Physics & Materials Science Congress & Exhibition, 20.-28.10.2019, Fethiye- Mugla, Turkey

Permalink: https://www.hzdr.de/publications/Publ-29814


The quest for AMS of ¹⁸²Hf – why poor gas gives pure beams

Martschini, M.; Lachner, J.; Merchel, S.; Priller, A.; Steier, P.; Wallner, A.; Wieser, A.; Golser, R.

Abstract

The trace isotope ¹⁸²Hf (T1/2 = 8.9 Ma) is of high astrophysical interest as its potential abundance in environmental archives would provide rare insight into heavy element nucleosynthesis in recent r-process events in the vicinity of our planet. Despite substantial efforts, however, it could not be measured at its natural abundance level with conventional AMS so far due to strong isobaric interference from stable ¹⁸²W.
The new Ion Laser InterAction Mass Spectrometry (ILIAMS) technique at VERA tackles the problem of elemental selectivity in AMS with a novel approach. It achieves near-complete suppression of isobar contaminants via selective laser photodetachment of decelerated anion beams in a gas-filled radio frequency quadrupole (RFQ). The technique exploits differences in electron affinities (EA) within elemental or molecular isobaric systems neutralizing anions with EAs smaller than the photon energy. Alternatively, these differences in EA can also result in anion separation via chemical reactions with the buffer gas.
In this contribution, we present first results with this approach on AMS-detection of ¹⁸²Hf. With He +O₂ mixtures as buffer gas in the RFQ, suppression of ¹⁸²WF₅- vs ¹⁸⁰HfF₅- by >10⁵ has been demonstrated. Mass analysis of the ejected anion beam identified the formation of oxyfluorides as an important reaction channel.
The overall Hf-detection effciency at VERA presently is 1.4 x 10-3 and the W-corrected blank value is ¹⁸²Hf/¹⁸⁰Hf = (3.4 + 2.1) x 10-14. In addition, a survey of several sputter materials for highest negative ion yields of HfF₅- has been conducted.

Keywords: AMS; Laser; astrophysics

Permalink: https://www.hzdr.de/publications/Publ-29813


Enhanced Fiberoptical Dosimetry through Time-resolved Single Photon Detection in Proton Fields

Kormoll, T.; van der Graaf, E. R.; van Goethem, M. J.; Gonzalez Torres, M. J.; Lachmann, P.; Pausch, G.; Majchrowski, A.; Makarevich, K.; Weinberger, D.; Zuber, K.; Teichmann, T.

Abstract

Fiberoptical dosimetry uses compact solid state radioluminescence probes coupled to long to flexible light guides. Such probes are convenient, robust small. Especially in the presence of magnetic fields, such optical probes can be advantageous over the transmission of a current signal, e.g. from a photodiode directly attached to a scintillator. These characteristics make such probes attractive for emerging medical applications like particle therapy in combination with MRI. Challenging remains the discrimination of so called “stem” effect light which is generated in the fiber from the actual signal light from the probe. In this work, fiber probes attached to a single photon sensor have been exposed to a proton beam from a proton cyclotron in order to study the feasibility of fiber dosimetry in therapeutic proton fields. Probes with different luminophores have been placed in the beam within a PMMA holder of 1 cm thickness. The light guide was coupled to a Hamamatsu H12386-210 single photon detector. For timing information, the pulse was sampled and analyzed with a Serious Dynamics DAQ125 board. This is a 16 bit sampling ADC board which was running synchronous to the cyclotron. An interpolated time stamp with a resolution of 30 ps was calculated in realtime. It could be shown that a time resolved measurement of the single luminescence photons exhibits the time structure of the luminophore, e.g. the long decay which appears uncorrelated of beryllium oxide or lithium tetraborate or the decay in the ns range of plastic scintillators. Blank fiber measurements exhibit the microbunch width of the accelerator. Thereby, stem identification in therapeutic hadron fields is possible without further reference measurements. Additionally, the issue of quenching of many luminophores in hadron fields can be addressed. A further beamtime at the AGOR cyclotron in Groningen will be conducted in May 2019 and recent results will be presented at the conference.

Keywords: Fiberoptical dosimetry; radioluminescence; magnetic fields; scintillator; MRI; proton beam; therapeutic proton fields; timing; ADC; beryllium oxide; lithium tetraborate; therapeutic hadron fields

  • Contribution to proceedings
    2019 IEEE Nuclear Science Symposium & Medical Imaging Conference, 26.10.-02.11.2019, Manchester, UK
    Proceedings of the 2019 IEEE Nuclear Science Symposium & Medical Imaging Conference

Permalink: https://www.hzdr.de/publications/Publ-29812


Crystal size versus paddle wheel deformability: selective gated adsorption transitions of the switchable metal–organic frameworks DUT-8(Co) and DUT-8(Ni)

Ehrling, S.; Senkovska, I.; Bon, V.; Evans, J. D.; Petkov, P.; Krupskaya, Y.; Kataev, V.; Wulf, T.; Krylov, A.; Vtyurin, A.; Krylova, S.; Adichtchev, S.; Slyusareva, E.; Weiss, M. S.; Büchner, B.; Heine, T.; Kaskel, S.

Abstract

Switchable pillared layer metal–organic frameworks M₂(2,6-ndc)₂(dabco) (DUT-8(M), M = Ni, Co, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]octane, DUT – Dresden University of Technology) were synthesised in two different crystallite size regimes to produce particles up to 300 μm and smaller particles around 0.1 μm, respectively. The textural properties and adsorption-induced switchability of the materials, obtained from both syntheses, were studied by physisorption of N2 at 77 K, CO2 at 195 K and n-butane at 273 K, revealing pronounced differences in adsorption behavior for Ni and Co analogues. While the smaller nano-sized particles (50–200 nm) are rigid and show no gating transitions confirming the importance of crystallite size, the large particles show pronounced switchability with characteristic differences for the two metals resulting in distinct recognition effects for various gases and vapours. Adsorption of various vapours demonstrates consistently a higher energetic barrier for the “gate opening” of DUT-8(Co) in contrast to DUT-8(Ni), as the “gate opening” pressure for Co based material is shifted to a higher value for adsorption of dichloromethane at 298 K. Evaluation of crystallographic data, obtained from single crystal and powder X-ray diffraction analysis, showed distinct geometric differences in the paddle wheel units of the respective MOFs. These differences are further disclosed by solid-state UV-vis, FT-IR and Raman spectroscopy. Magnetic properties of DUT-8(Co) and DUT-8(Ni) were investigated, indicating a high-spin state for both materials at room temperature. Density functional theory (DFT) simulations confirmed distinct energetic differences for Ni and Co analogues with a higher energetic penalty for the structural “gate opening” transformation for DUT-8(Co) compared to DUT-8(Ni) explaining the different flexibility behaviour of these isomorphous MOFs.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29811


Testing RPC Performance with Discharges Ignited by UV Laser Pulses: Precise measurement of gas parameters in approximately realistic RPC configurations

Fan, X.

Abstract

This thesis is devoted in two associated topics: a unique laser facility for researches of gaseous detectors; the investigations of Resistive Plate Chamber (RPC) detectors and the measurement of gas parameters in a realistic condition of timing RPC.
A pulsed UV laser test facility has been assembled in HZDR. The focus of pico-second laser pulses is placed in a specific position in a gaseous detector sample to produce laser plasma, where free electrons are generated in ionizations with well defined number, micro-meter spatial accuracy in a volume of micro-meter scale. It provides a method, independent from accelerators, to make investigations with gaseous detectors in a laboratory.
Samples of RPC detectors are designed and assembled for experiments with the laser test facility. Methods are developed to acquire the waveforms of electron avalanches for different drift lengths and to obtain the key gas parameters: the effective Townsend coefficient and the electron drift velocity. We have succeeded in the direct measurement of gas parameters at the field strength of timing RPC under atmospheric pressure for the first time in experimental conditions.
The research has obtained different achievements. The laser test facility is proven to be qualified for the measurement of gas parameters, and has a potential to contribute to the eco-gas research for future RPC. The possible measurement range of electric field of gas parameter at atmospheric pressure is extended by a factor of two, from the range of trigger RPC to timing RPC. The results of experiments have revealed some fundamental mechanisms, which will extend the understanding of RPC performance and electron avalanche process.

Keywords: Laser; Resistive Plate Chamber; Electron Avalanche

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-106 2019
    ISSN: 2191-8708, eISSN: 2191-8716

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29810


Comparison of Gas-Liquid Flow Characteristics in Geometrically Different Swirl Generating Devices

Putra, R. A.; Neumann-Kipping, M.; Schäfer, T.; Lucas, D.

Abstract

The gas-liquid flow characteristics for the blade, the single and the double-helical swirl elements were numerically investigated and compared in this work. The Euler-Euler model assuming bi-modal bubble size distributions was used. The experiment conducted in a vertical pipe equipped with a static blade swirl element is used as the basis for the CFD simulations. In the experiment, the high-resolution gamma-ray computed tomography (HireCT) was used to measure the gas volume fractions at several planes within the blade swirl element. The resulting calculated profiles of the pressure, liquid and gas velocities, as well as the gas fraction, show a large influence of the swirl elements geometry. The evolution and the characteristic of the calculated gas/liquid phase distributions in different measurement planes are found to be unique for each type of swirl elements. A single gas core in the center of the pipe is observed from the simulation of the blade element while multiple cores are observed from the simulation of the single and double helix elements. The cross-sectional gas distribution downstream the single and double helical elements change drastically within a relatively short distance downstream the elements. In contrast, the single gas core downstream the blade element is more stable.

Keywords: Swirling flow; Multiphase flow; Inline separator; Static mixer; CFD simulation, Euler-Euler

Permalink: https://www.hzdr.de/publications/Publ-29809


Cerebellar volume reduction after photon or proton radio(chemo)therapy of glioblastoma patients

Raschke, F.; Seidlitz, A.; Platzek, I.; Beuthien-Baumann, B.; van den Hoff, J.; Krex, D.; Kotzerke, J.; Jentsch, C.; Baumann, M.; Krause, M.; Troost, E. G. C.

Abstract

Purpose or Objective:

Radio(chemo)therapy is part of the standard treatment of high-grade glioma patients and has been associated with cerebral atrophy [1,2]. Preclinical work also suggests radiation induced atrophy of the cerebellum [3,4]. Investigating cerebellar atrophy in patients treated with radiation is a further step in understanding radiation-induced deficits in both motor function and cognition. The aim of this study was to investigate cerebellar volume changes in a cohort of glioblastoma patients treated with photon or proton radio(chemo)therapy.

Material and Methods:

Data was acquired on a 3T Philips Ingenuity TF PET/MRI scanner (Philips Healthcare, Best, The Netherlands) as part of a prospective, longitudinal study investigating the effect of 11C-methionine PET/MR for tailoring the treatment of patients with glioblastoma (NCT01873469). In total, 71 patients with cerebral GBM (21 treated with proton therapy) had a baseline MR and at least one follow-up MRI, obtained in 3 monthly intervals after irradiation, available, including 3D T1-weighted (T1w) imaging (1×1×1 mm3) before and after intravenous injection of contrast agent (CE). Patients were treated with a total dose of 60 Gy(RBE=1.1) delivered in 2Gy fractions. On average 3.6 follow-ups were available covering a time period of 413 days ± 432 days (mean ± SD).

The cerebellum was cut out from each MRI by warping [5] the MNI152 brain atlas and a corresponding cerebellar mask to each brain extracted T1w MRI. Sigmoid and transverse sinuses mimicking cerebellar tissue were removed using the CE T1w MRI. The cerebellum was segmented into grey matter (GM), white matter (WM) and cerebrospinal fluid (CSF) [6]. Its volume was calculated as the sum of all GM and WM probabilities and normalized to the baseline value for each patient. The mean relative cerebellar volume change per year was estimated for each patient with a linear regression. The resulting rate of volume change per year was plotted against the mean dose delivered to the cerebellum across all patients, and the rate of volume change per year per dose was subsequently estimated using a linear regression.

Results:

Figure 1 illustrates segmentation of the cerebellum. Mean cerebellar dose for patients treated with protons and photons was 1.7Gy ± 2.1Gy and 5.7Gy ± 4.6Gy, respectively. The linear model estimated a cerebellar volume loss of approx. 1.8% per 10Gy per year (p<0.001; Fig. 2). This is similar to that estimated in the cerebrum of the same patient cohort [2].

Conclusion:

Cerebellar volume loss after radio(chemo)therapy is related to the mean cerebellar dose. The atrophy rate is similar to that previously found in the cerebrum. Additional work is needed to further validate those findings and relate them to cognitive and motor performance.

[1] Prust et al. Neurology 2015;85:683-691
[2] Petr et al. Radiother Oncol 2018;128:121-127
[3] Zhou et al. Sci Rep-UK 2017;7:46181
[4] Eekers et al. Clin Transl Radiat Oncol 2018;8:22-26
[5] Avants et al. NeuroImage 2011;54:2033–2044
[6] Avants et al. Neuroinformatics 2011;9:381-400

Keywords: radiotherapy; cerebellum; atrophy; proton therapy; photon therapy; irradiation; normal tissue

Involved research facilities

  • PET-Center
  • Contribution to proceedings
    ESTRO 2020, 03.-07.04.2020, Wien, Österreich
    Proceedings of ESTRO 2020

Permalink: https://www.hzdr.de/publications/Publ-29808


First systematic clinical study on detection of anatomical changes in PT using prompt-gamma imaging

Berthold, J.; Jost, A.; Khamfongkhruea, C.; Petzoldt, J.; Thiele, J.; Hölscher, T.; Wohlfahrt, P.; Pausch, G.; Janssens, G.; Smeets, J.; Richter, C.

Abstract

Purpose & Objective
Anatomical changes during the course of proton therapy treatment can result in relevant changes in proton range, potentially causing severe under- or overdosage. Verifying the proton treatment, ideally in real-time, is thus highly desirable. Here, we present the first systematic evaluation of the sensitivity of a prompt-gamma-imaging (PGI) based range verification system to detect anatomical changes in prostate-cancer treatments.

Materials & Methods
A PGI slit-camera system was clinically applied to monitor spot-wise proton range deviations during 7 and 9 fractions of hypo-fractionated pencil beam scanning (PBS) treatment for 2 prostate-cancer patients, respectively (2 opposing fields, 1.5 GyE each). For all monitored fractions, in-room control CT scans (cCT) were acquired in treatment position, serving as ground-truth reference. Based on the evaluation of planning CT (pCT) and cCT data on the level of CT images, dose distributions and derived line-dose profiles, anatomical changes were identified and scored concerning cause and magnitude. The detectability of these changes with PGI was determined by manually comparing expected range shifts from line-dose profiles (pCT vs. cCT) with PGI-derived spot-wise range shifts for distal PBS spots (Fig.1). This evaluation was performed for both, measured as well as simulated PGI data based on cCT (no statistical uncertainty). Furthermore, the sensitivity for a binary differentiation between relevant (strong/moderate) and no relevant anatomical changes within a fraction was determined. Working towards an automated classification of treatment deviations for real-time treatment verification, a simple two-parametric model was established to classify each monitored field into global, local and not clinically relevant anatomical changes.

Results
From 64 detected anatomical changes in 32 monitored treatment fields, in total 66% (84%) were also identified by measured (simulated) PGI data (Fig.2a). All strong changes (14/64) were identified correctly. For the differentiation between relevant from non-relevant changes, a sensitivity of 69% (95%) was achieved for measured (simulated) PGI data. The first attempt for automated classification was able to reliably differentiate global from local changes (Fig.2b). However, it was more difficult to distinguish treatments with no relevant from local anatomical changes. Also in the ground-truth classification, this decision was sometimes also borderline.

Conclusion
In the first systematic investigation of the sensitivity of PGI-based treatment verification in clinical prostate-cancer treatments, its capability to detect strong anatomical changes has been clearly demonstrated. In clinical PGI application the sensitivity is a bit smaller than for idealized PGI simulations, still severe changes were detected for all cases. The next step is to establish a reliable automated interpretation of PGI data. In a first trial, we established a two-parametric prediction model with already encouraging results.

  • Lecture (Conference) (Online presentation)
    ESTRO 2020, 28.11.-01.12.2020, Wien, Österreich
  • Abstract in refereed journal
    Radiotherapy and Oncology 152(2020)Supplement, S244-S245
    DOI: 10.1016/S0167-8140(21)00465-5

Permalink: https://www.hzdr.de/publications/Publ-29807


First-in-man validation of CT-based stopping-power prediction using prompt-gamma range verification

Berthold, J.; Khamfongkhruea, C.; Jost, A.; Petzoldt, J.; Thiele, J.; Hölscher, T.; Wohlfahrt, P.; Hofmann, C.; Pausch, G.; Janssens, G.; Smeets, J.; Richter, C.

Abstract

Purpose & Objective
Currently, the uncertainty in CT-based range prediction is substantially impairing the accuracy of particle therapy. Direct determination of stopping-power ratio (SPR) from dual-energy CT (DECT) has been proposed (DirectSPR) and initial validation studies in phantoms and biological tissues have proven a superior accuracy. However, a validation of range prediction in patients has not been achieved by any means. Here, we present the first verification of CT based proton range prediction in patients, using prompt-gamma imaging (PGI).

Materials & Methods
A PGI slit camera system of improved positioning accuracy, using a floor-based docking station, was developed. Its accuracy and positioning reproducibility were determined with x-ray and PGI measurements. The PGI system was clinically applied to monitor absolute proton ranges for a 1.5 GyE field during hypo-fractionated treatment of 3 prostate-cancer patients using pencil beam scanning (PBS) (Fig. 1). Per patient 3 fractions were monitored. For all monitored fractions, in-room control-CT (cCT) scans were acquired in treatment position enabling PGI-based spot-by-spot range analysis for the actual patient anatomy: The PGI measurements were compared to simulations of the expected PGI signal based on the respective cCT. Three different SPR prediction models were applied in the simulation: A standard CT-number-to-SPR conversion (Std-HLUT), a HLUT optimized with DECT-derived SPR information (Adapt-HLUT), and the directly voxel-wise calculated SPR based on the input from DECT (DirectSPR). To verify range prediction in patients, the histogram of PGI-derived range shifts from all PBS spots was analyzed concerning its Gaussian mean – acting as surrogate for the accuracy of the respective range prediction method. It is independent from random uncertainty contributions (e.g. positioning, statistical uncertainty in shift determination).

Results
The accuracy and precision for global PGI range verification (averaging over multiple spots) was determined to be 0.7 mm (2σ) and 1.3 mm (2σ), respectively. The precision is limited by remaining uncertainties in image registration and positioning reproducibility (1.1 mm, 2σ). Hence, the absolute verification uncertainty of the cumulative mean shift (for 9 monitored fractions) is 0.8 mm (2σ), which is smaller than the range prediction uncertainty for deep-seated tumors (about 10 mm for prostate treatments).
The comparison of the PGI-measured and predicted spot-wise ranges for in total 12000 PBS spots from the 9 analyzed fractions resulted in an range prediction offset of 0.6 mm, 1.3 mm and 4.4 mm, for the DirectSPR, Adapt-HLUT and Std-HLUT approaches, respectively.

Conclusion
The accuracy of PGI-based range verification was improved to enable the worldwide first in-man validation of CT-based stopping-power prediction. The evaluation of the first clinical PGI data for prostate-cancer treatments, systematically acquired within a clinical study, confirms the superiority of DECT-based range prediction in patients.

  • Lecture (Conference) (Online presentation)
    ESTRO 2020, 28.11.-01.12.2020, Wien, Österreich
  • Abstract in refereed journal
    Radiotherapy and Oncology 152(2020)Supplement, S390-S391
    DOI: 10.1016/S0167-8140(21)00720-9

Permalink: https://www.hzdr.de/publications/Publ-29806


Modular Digital Low Level Radio Frequency Control (LLRF) for CW Operation at ELBE

Zenker, K.

Abstract

A digital LLRF control has been implemented at the CW linac ELBE at Helmholtz-Zentrum Dresden-Rossendorf. The system is based on the MicroTCA.4 standard and drives four superconducting TESLA cavities and two normal conducting buncher cavities. The system enables a higher flexibility of the field control, improved diagnostics and field stability compared to the analogue system which was used before. The presentation will give an overview on the design specification, detailed system structure, software architecture and latest performance test results.

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    19th International Conference on RF Superconductivity, 30.06.-05.07.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29805


Validating gene signatures in locally advanced HNSCC patients treated by PORT-C and in xenografts

Patil, S. G.; Linge, A.; Tawk, B.; Gurtner, K.; Großer, M.; Lohaus, F.; Gudziol, V.; Nowak, A.; Tinhofer, I.; Budach, V.; Stuschke, M.; Balermpas, P.; Rödel, C.; Schäfer, H.; Grosu, A.-L.; Abdollahi, A.; Debus, J.; Belka, C.; Combs, S. E.; Mönnich, D.; Zips, D.; Baretton, G. B.; Krause, M.; Baumann, M.; Löck, S.

Abstract

Purpose or Objective:

To personalize radiotherapy of locally advanced head and neck squamous cell carcinoma (HNSCC), gene signatures have been developed that are related to processes involved in radioresistance of HNSCC. To date, most of these signatures were developed for patients who have received primary radiotherapy (pRCTx). The aim of our study was (I) to apply existing gene signatures related to different radio-biological processes for patients treated with postoperative radiochemotherapy (PORT-C) and (II) to validate these signatures in xenograft models.

Material and Methods:

This study is based on two cohorts: (i) 128 patients with locally advanced HVP16 DNA-negative HNSCC who received PORT-C in a multicentre retrospective study of the German Cancer Consortium Radiation Oncology Group (DKTK-ROG) between 2005 and 2011 and (ii) 60 mice bearing xenografts of 10 cell lines of human squamous cell carcinoma. Gene signatures related to cancer stem cell (CSC) markers [1], DNA repair [2], hypoxia [3], radiosensitivity [4] and epithelial mesenchymal transition (EMT) [5] were selected. Whole transcriptome analysis was performed using the HTA 2.0 Array (Affymetrix). Based on the gene signatures, risk groups were generated as described in the original publications (i) for the PORT-C cohort and (ii) for the xenograft data. The primary endpoint for the PORT-C cohort was loco-regional control (LRC), while the endpoint for the xenograft data was the dose to control 50% of the tumours (TCD50). The endpoints were evaluated byCox regression and the Mann-Whitney-U test, respectively.

Results:

All signatures were able to stratify patients treated with PORT-C into risk groups with a significant difference in LRC (figure A) or showed a statistical trend (radiosensitivity signature). This was confirmed in multivariable Cox regression including age and T stage. In the xenograft models, the gene signatures based on cancer stem cell markers, hypoxia and radiosensitivity showed a significant association with TCD50 (figure B).The correlations between these three gene signatures were weak (R<0.2).

Conclusion:

In our study, we successfully transferred gene signatures that were developed for patients with locally advanced HNSCC treated mainly by pRCTx to a patient cohort treated by PORT-C. Furthermore, cancer stem cell markers, hypoxia-associated genes and a radiosensitivity signature were able to stratify xenografts with respect to the TCD50. Since these signatures were weakly correlated, they may be considered as independent and robust biomarkers for future personalized radiotherapy of patients with locally advanced HNSCC.

References:

[1] Linge et al. Radiother Oncol 121: 364 (2016).
[2] Shen et al. Oncol Rep 83: 3403 (2017).
[3] Toustrup et al. Cancer Res 71: 5923 (2011).
[4] Kim et al. BMC Genomics; 13: 348 (2012).
[5] Chung et al. Cancer Res; 66: 8210 (2006).

Keywords: Personalised medicine

  • Invited lecture (Conferences) (Online presentation)
    ESTRO 2020, 28.11.-01.12.2020, Online Congress, Online Congress

Permalink: https://www.hzdr.de/publications/Publ-29804


ELBE and DALI at HZDR

Zenker, K.; Evtushenko, P.; Schwarz, A.; Kuntzsch, M.; Schneider, C.; Kovalev, S.

Abstract

Facility status report for ELBE and TELBE

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    MT ARD ST3 Annual Meeting, 16.-18.10.2019, Darmstadt, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29803


Modelling and external validation of late side effects of brain tumours following proton therapy

Dutz, A.; Agolli, L.; Bütof, R.; Lühr, A.; Baumann, M.; Vermeren, X.; Geismar, D.; Lamba, N.; Schapira, E. F.; Bussière, M.; Daly, J. E.; Bussière, M. R.; Krause, M.; Timmermann, B.; Shih, H. A.; Löck, S.

Abstract

Purpose:

To investigate late physician-rated side effects and their association with dosimetric parameters of various organs at risk (OARs) as well as clinical cofactors in adult brain tumour patients following proton beam therapy (PBT).

Material and methods: Adult patients with brain tumours who underwent PBT at three different institutes were included in this study (N1=57, N2=47, N3=63). The radiation-induced side effects alopecia, fatigue, headache, memory impairment, hearing impairment, optic nerve disorder, dry eye and seizure (CTCAE v4.0) at 12 and 24 months after PBT were investigated. Side effects with sufficiently high incidence were dichotomised and correlated to different dose-volume histogram (DVH) parameters of associated OARs, such as skin, remaining brain, brainstem, cerebellum, hippocampi and cochlea. Clinical parameters comprised age, gender, tumour volume, prescribed dose, concomitant chemotherapy, resection of the tumour, diagnosis and WHO grading. Normal tissue complication probability (NTCP) models were developed on a combined cohort from two institutes (N=104) using logistic regression. The area under the receiver operating characteristic curve (AUC) was used to assess the prognostic ability in external validation on the remaining cohort.

Results: In all cohorts, low toxicity rates were observed at 12 and 24 months after PBT. Most common side effects were fatigue (grade≥1: 32%/27%, grade≥2: 14%/6% at 12/24 months), alopecia (grade≥1: 30%/22%) and mild memory impairment (grade≥1: 23% at 24 months). Mild headache and hearing impairment (grade≥1) occurred in 20%/19% and 8%/9% of all patients at 12/24 months, respectively. Logistic regression revealed significant correlations between the incidence of alopecia grade≥1 at both times and high dose regions of the skin (D2%, p<0.001, figure A). Hearing impairment grade≥1 at 24 months after PBT was associated with the median dose to the ipsilateral cochlea. For both endpoints, the developed NTCP models were successfully validated (AUC≥0.78, figure B).

Conclusion: Significant correlations between the occurrence of late side effects and DVH parameters of associated OARs were observed and externally validated for patients with brain tumours receiving PBT. Similar DVH parameters were associated to late alopecia as described for early alopecia following PBT [1]. The relation between median cochlear dose and persistent hearing loss is in agreement with several studies on photon therapy patients. In the future, these NTCP models in combination with models on neurocognition may be used to identify patients who are likely to benefit most from PBT.

[1] Dutz A et al. (2019) Radiother Oncol 130, 164-171.

Keywords: Normal tissue; CNS; proton beam therapy

  • Lecture (Conference)
    ESTRO 39, 03.-07.04.2020, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-29801


Proximity effect in crystalline framework materials: stacking-induced functionality in MOFs and COFs

Kuc, A. B.; Springer, M.; Batra, K.; Juarez-Mosqueda, R.; Wöll, C.; Heine, T.

Abstract

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) consist of molecular building blocks being stitched together by strong bonds. They are well known for their porosity, large surface area, and related properties. The electronic properties of most MOFs and COFs are the superposition of those of their constituting building blocks. If crystalline, however, solid-state phenomena can be observed, such as electrical conductivity, substantial dispersion of electronic bands, broadened absorption bands, formation of excimer states, mobile charge carriers, and indirect band gaps. These effects emerge often by the proximity effect caused by the van-der-Waals interactions between stacked aromatic building blocks. This Progress Report shows how functionality is imposed by this proximity effect, that is, by stacking aromatic molecules in such a way that extraordinary electronic and optoelectronic properties emerge in MOFs and COFs. After discussing the proximity effect in graphene-related materials, its importance for layered COFs and MOFs is shown. For MOFs with well-defined structure, the stacks of aromatic building blocks can be controlled via varying MOF topology, lattice constant, and by attaching steric control units. Finally, an overview of theoretical methods to predict and analyze these effects is given, before the layer- by-layer growth technique for well-ordered surface-mounted MOFs is summarized.

Permalink: https://www.hzdr.de/publications/Publ-29800


Morphology modification of Si nanopillars under ion irradiation at elevated temperatures: plastic deformation and controlled thinning to 10 nm

Xu, X.; Heinig, K.-H.; Möller, W.; Engelmann, H.-J.; Klingner, N.; Gharbi, A.; Tiron, R.; Borany, J.; Hlawacek, G.

Abstract

Si nanopillars of less than 50 nm diameter have been irradiated in a helium ion microscope with a focused Ne+ beam. The morphological changes due to ion beam irradiation at room temperature and elevated temperatures have been studied with the transmission electron microscope. We found that the shape changes of the nanopillars depend on irradiation-induced amorphization and thermally driven dynamic annealing. While at room temperature, the nanopillars evolve to a conical shape due to ion-induced plastic deformation and viscous flow of amorphized Si, simultaneous dynamic annealing during the irradiation at elevated temperatures prevents amorphization which is necessary for the viscous flow. Above the critical temperature of ion-induced amorphization, a steady decrease of the diameter was observed as a result of the dominating forward sputtering process through the nanopillar sidewalls. Under these conditions the nanopillars can be thinned down to a diameter of ∼10 nm in a well-controlled manner. A deeper understanding of the pillar thinning process has been achieved by a comparison of experimental results with 3D computer simulations based on the binary collision approximation.

Keywords: helium ion microscopy; Monte Carlo simulation; sub-10 nm fabrication; ion beam damage; amorphization

Involved research facilities

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29799


Interaction of curium(III) with surface-layer proteins from Lysinibacillus sphaericus JG-A12

Moll, H.; Lehmann, F.; Raff, J.

Abstract

Trivalent actinides such as Cm(III) are able to occupy natural Ca(II) binding sites in biological systems. For this investigation, we studied the formation of aqueous Cm(III) complexes with S-layer proteins by time-resolved laser-induced fluorescence spectroscopy (TRLFS). S-layer proteins serve as protective biointerfaces in bacteria and archaea against the surrounding solution. Experimental assays were performed at a fixed total concentration of Cm(III) (0.88 µM) using an S-layer protein (5 g/L / 39.6 µM) at varying pH levels (2.0 to 9.0), as well as several types of S-layer proteins of L. sphaericus JG-A12. Based on resulting luminescence spectra and lifetime data, specific and unspecific binding sites could be distinguished. Notably, specific Cm(III) binding to S-layer proteins was confirmed by the appearance of a sharp emission band at 602.5 nm, combined with a long lifetime of 310 µs. The high affinity of these specific binding sites was also verified using competing EDTA, wherein only a high EDTA concentration (40 µM) could efficiently remove Cm(III) from S-layer proteins.

Keywords: curium; S-layer proteins; Lysinibacillus sphaericus; luminescence spectroscopy, speciation

Downloads

  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-29798


Design of Flexible Plants

van den Boogaart, K. G.; Tolosana Delgado, R.; Rudolph, M.; Reuter, M.

Abstract

Geometallurgy brought the promise of adaptively processing the ore in the best possible way, depending on its local properties. Particle based modelling of processing allows to compute economically optimal processing parameters and configurations, given the flexibility of the plant, its capacity limits and the feed properties. In theory a flexible processing could increase the economic value substantially.

Real plants are designed for a constant feed and real operations use blending to homogenize the feed. This contribution analyses what features would make a plant design sufficiently flexible to exploit this theoretical superiority of adaptive processing. One can quantify the economic effect of the various options for flexibility, such as extra capacity in various steps, controlled or regulated machine settings including online measurements, intermediate storage and sorted stockpiling, variable residence time in feedback loops, rerouting, and parallel processing units.

We model the adaptive processing situation by a bivariate distribution of the properties of and knowlege about selective feed units (SFU) analogous to selective mining units (SMU), but larger. Using a forward simulator we can compute the optimal parameterisation of the plant as a function of the knowledge about SFU. Depending on the flexibility of the plant we get a different mean economic effect of picking the choice with the highest value. This value is computed as a difference of selling price of products and the processing and dumping costs. Averaging over all units we can compute a mean value. The difference of this mean to the optimal fixed processing setting a global ore blend provides the value of the given flexibility option. A more flexible plant also has a higher CAPEX. Comparing the discounted value of flexibility to this CAPEX one can select the optimal flexibility for the plant.

Keywords: Flexible Plant; Geometallurgy; Simulation; Plant Design

  • Lecture (Conference)
    IMPC2020 XXX International Mineral Processing Conference, 18.-22.10.2020, Cape Town, Sourth Africa

Permalink: https://www.hzdr.de/publications/Publ-29797


Automated SEM Mineral Liberation Analysis (MLA) with Generically Labelled EDX Spectra in the Mineral Processing of Rare Earth Element Ores

Schulz, B.; Merker, G.; Gutzmer, J.

Abstract

Many rare earth element (REE) deposits have experienced multistage geological enrichment processes resulting in REE bearing mineral assemblages of considerable complexity and variability. Automated scanning electron microscopy (SEM) mineral liberation analysis of such REE ores is confronted by the difficult assignment of energy-dispersive X-ray (EDX) spectra to REE mineral names. To overcome and bypass this problem, a generic and reliable labelling of EDX reference spectra obtained from REE-bearing minerals based on their contents of Si, Ca, F and P in a bulk normalised analysis is proposed. The labelled spectra are then combined into groups of REE-P (similar to monazite), REE-Ca-Si-P (similar to britholite), REE-Ca-F (similar to synchysite) and REE-F (similar to bastnaesite, parisite, fluocerite). Mixed spectra with low counts for REE from minute REE mineral grains are combined into a separate group. This classification scheme is applied to automated SEM mineral liberation analysis (MLA) data from beneficiation products by comminution and multistage flotation of REE carbonatite ores. Mineral modes, mineral grain size distribution, mineral liberation, mineral locking and mineral grade versus recovery curves based on the analysis of >200,000 particles in a sample can be recognised and interpreted in virtual grain size fractions. The approach as proposed here will allow future process mineralogical studies of REE deposits to be robust and comparable.

Permalink: https://www.hzdr.de/publications/Publ-29796


Uranium and neptunium retention mechanisms in Gallionella ferruginea / ferrihydrite systems for remediation purposes

Krawczyk-Bärsch, E.; Scheinost, A. C.; Roßberg, A.; Müller, K.; Lehrich, J.; Bok, F.; Hallbeck, L.; Schmeide, K.

Abstract

The ubiquitous β-Proteobacterium Gallionella ferruginea is known as stalk-forming, microaerophilic iron(II) oxidizer, which rapidly produces iron oxyhydroxide precipitates. Uranium and neptuniump sorption to the resulting intermixes of G. ferruginea cells, stalks, extracellular exudates and precipitated iron oxyhydroxides (BIOS) was compared to sorption to abiotically formed iron oxides and oxyhydroxides. The results show a high sorption capacity of BIOS towards radionuclides at circumneutral pH values with an apparent bulk distribution coefficient (Kd) of 1.23×10 E4 L/kg for uranium and 3.07×10 E5 L/kg for neptunium. The spectroscopic approach by XAS and ATR FT-IR spectroscopy, which was applied on BIOS samples, showed the formation of inner-sphere complexes. The structural data obtained at the uranium LIII-edge and the neptunium LIII-edge indicate the formation of bidentate edge-sharing surface complexes which are known as the main sorption species on abiotic ferrihydrite. Since the rate of iron precipitation in G. ferruginea dominated systems is 60 times faster than in abiotic systems, more ferrihydrite will be available for immobilization processes of heavy metals and radionuclides in contaminated environments and even in the far-field of high-level nuclear waste repositories.

Keywords: actinides; sorption; microorganism; bacteriogenic iron oxyhydroxides; XAS; ATR FT-IR spectroscopy

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29795


Independent Geometrical Control of Spin and Charge Resistances in Curved Spintronics

Das, K. S.; Makarov, D.; Gentile, P.; Cuoco, M.; van Wees, B. J.; Ortix, C.; Vera-Marun, I. J.

Abstract

Spintronic devices operating with pure spin currents represent a new paradigm in nanoelectronics, with a higher energy efficiency and lower dissipation as compared to charge currents. This technology, however, will be viable only if the amount of spin current diffusing in a nanochannel can be tuned on demand while guaranteeing electrical compatibility with other device elements, to which it should be integrated in high-density three-dimensional architectures. Here, we address these two crucial milestones and demonstrate that pure spin currents can effectively propagate in metallic nanochannels with a three-dimensional curved geometry. Remarkably, the geometric design of the nanochannels can be used to reach an independent tuning of spin transport and charge transport characteristics. These results laid the foundation for the design of efficient pure spin current-based electronics, which can be integrated in complex three-dimensional architectures.

Keywords: curved nanoarchitectures; electrical and spin resistance; geometrical control; nonlocal spin valves; Spintronics

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29794


Numerical and Experimental Investigation of Electro-Vortex Flow in a Cylindrical Container

Liu, K.; Stefani, F.; Weber, N.; Weier, T.; Li, B.-W.

Abstract

In a cylindrical container filled with an eutectic GaInSn alloy, an electro-vortex flow (EVF) is generated by the interaction of a non-uniform current with its own magnetic field. In this paper, we investigate the EVF phenomenon numerically and experimentally. Ultrasound Doppler Velocimetry (UDV) is applied to measure the velocity field in a cylindrical vessel. Second, we enhance an old numerical solver by taking into account the effect of Joule heating, and employ it for the numerical simulation of the EVF experiment. Special focus is laid on the role of the magnetic field, which is the combination of the current induced magnetic field and the external geomagnetic field. For getting a higher computational efficiency, the so-called parent-child mesh technique is applied in OpenFOAM when computing the electric potential, the current density and the temperature in the coupled solid-liquid conductor system. The results of the experiment are in good agreement with those of the simulation. This study may help to identify the factors that are essential for the EVF phenomenon, and for quantifying its role in liquid metal batteries.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29793


Effects of Magnetic Field on Hydrogen Bubble Detachment during Water Electrolysis

Yang, X.; Mutschke, G.; Margitta, U.; Eckert, K.

Abstract

Water electrolysis is a promising option for hydrogen production from renewable resources. One main challenge in making water electrolysis economically competitive is to raise its efficiency by decreasing the cell voltage. In this respect, electrode coverage by gas bubbles is one of the key sources which creates undesired overpotential.

Better understanding of the fundamentals of bubble nucleation, growth, and detachment in detail might bring new ideas in such effective manipulating of bubbles and substantially accelerate a way toward advanced electrolysis. Despite extensive efforts in the past, important aspects of bubble dynamics, such as the interaction/coalescence of bubbles significantly affecting their evolution or different growth modes of the bubbles themselves, are not yet fully understood. To provide that necessary information on the bubble shape profile, including the contact angle, the contact line the bubble forms with the electrode [1], the Marangoni convection[2], we use a micro electrode to produce single hydrogen bubbles. Water electrolysis was carried out under potentiostatic conditions in a 1 M H2SO4 solution in a small electrochemical cell ([2], [3], [4]). The behavior of a single hydrogen bubble evolving on a microelectrode (100 µm in diameter) was analyzed by measurements of the current transient as well as by microscopic high speed imaging. Tracer particles were additionally added to the solution to measure the flow in the vicinity of the bubble.

The contribution will present experimental results of the hydrogen bubble release size and the bubble growing mechanism at two different magnetic field orientations and at different field intensities. As shown in Fig.1, the bubble departure size decreased with increase of the magnetic field intensity when the magnetic field was applied parallel to the electrode surface. However, an increase of the departure size was observed when the field was applied perpendicular to the electrode surface. The effects were further explained by the MHD convection around the bubble. A comparison of the flow field by measurements and numerical simulation will be presented.

  • Lecture (Conference)
    The 8th International Conference on Magneto-Science, 10.-14.10.2019, Hefei, China

Permalink: https://www.hzdr.de/publications/Publ-29792


The effect of hypoxia on the induction of strand breaks in plasmid DNA by alpha-, beta- and Auger electron-emitters 223Ra, 188Re, 99mTc and DNA-binding 99mTc-pyrene

Reissig, F.; Wunderlich, G.; Runge, R.; Freudenberg, R.; Lühr, A.; Kotzerke, J.

Abstract

Radiation-induced DNA damage occurs as a consequence of both direct and indirect effects of ionizing radiation. The induction mechanism of DNA damage is mainly influenced by the physical characteristics of the radiation quality, especially the linear energy transfer. In general, hypoxia reduces the effect of irradiation treatment in tumor cells and leads to poor patient outcomes. Emitters with high linear energy transfer (alpha- or Auger-electron-emitters) can overcome this obstacle. Our aim is to demonstrate the influence of hypoxia on the interaction between different radiation qualities with DNA by using a cell free plasmid model modulated by the free radical scavenger dimethyl sulfoxide (DMSO).
Plasmid DNA was irradiated with 223Ra, 188Re, 99mTc and DNA-binding 99mTc-pyrene in the absence or presence of DMSO and either under normoxic or hypoxic conditions. The resulting DNA damage in form of single- (SSB) and double strand breaks (DSB) was analyzed by agarose gel electrophoresis. Applied radiation doses of up to 200 Gy of 223Ra, 188Re or 99mTc or 60 Gy of 99mTc-pyrene led to maximal yields of SSB (80%) in plasmid DNA. Irradiation with 223Ra, 188Re or 99mTc at 200 Gy induced 30%, 28% and 32% linear plasmid conformations, respectively, which are associated with DSB. Hypoxia had a minor effect on SSB and DSB induction from 223Ra but a small enhancement in DSB for 188Re and 99mTc. DMSO could prevent DSB completely and SSB DNA damage from the three “free” radionuclides to comparable levels. DNA-binding 99mTc-pyrene induced less SSB and DSB compared to free 99mTcO4- due to its own radical scavenging properties. However, an additional incubation of DMSO could prevent the SSB and DSB induction only to a minor extent. Direct insults of Auger-electrons from 99mTc-pyrene are more effective than high-energy electrons or alpha particles due to the minimal distance between the radionuclide and the DNA.
We conclude that hypoxia does not limit DNA damage in plasmids induced by 223Ra, 188Re, 99mTc and 99mTc-pyrene. Dose-dependent radiation effects were comparable for alpha-emitters and both high- and low-energy electron emitters. The radioprotection by DMSO was not influenced by hypoxia. Overall, the results indicate the contribution of mainly indirect radiation effects for 99mTc, 188Re and 223Ra. 99mTc-pyrene caused direct DNA damages. The direct participation of oxygen in cell-free plasmid DNA damage induction was not proven.

Keywords: hypoxia; plasmid DNA; α-emitter; Auger-electrons; DMSO

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29791


Shrinking-field concept spars the periventricular region in proton therapy of gliomas

Eulitz, J.; Hahn, C.; Raschke, F.; Karpowitz, C.; Enghardt, W.; Troost, E. G. C.; Krause, M.; Lühr, A.

Abstract

Recent findings suggest an increased radiosensitivity of the cerebral periventricular region (PVR; Eulitz 2019, Harrabi 2019) in primary brain tumor patients. Shrinking-field concepts (SFC) are used in proton therapy, e.g. of the brain, to spare normal brain tissue. Since there is a correlation between treatment associated brain injury and dose / LET (Peeler 2019), the evaluation of the impact of SFC in PVR dose and LET sparing is necessary. We compared observed radiation-induced brain injuries after proton therapy for glioma patients treated either conventional (CC) or with SFC, and introduce an approach for PVR-adapted proton treatment planning.

All grade II and III glioma patients treated between 2014 and 2018 with (adjuvant) proton radio(chemo)therapy to a total dose (D) of 54-60 Gy(RBE) were considered for analysis. 33% of the patients received SFC (with sequential- or simultaneously-integrated proton boost (SIB)) with a prescribed dose reduction of 6-10 Gy(RBE) in the outer part of the target volume. Contrast enhancements (CE) on follow-up MRI (fuMRI) diagnosed as treatment-related brain injury lesions (symptomatic or clinically silent) were traced back to the fuMRI of first appearance, delineated and deformably co-registered to the planning CT. The distance between CE lesions to the cerebral ventricles was determined. The PVR was estimated as a 4 mm band around the segmented cerebral ventricles. The PVR volume VX% receiving more than X% of prescribed dose as well as D and LET within the CE lesions were calculated. Brain injury-free survival (in/outside PVR) was derived in a Kaplan-Meyer analysis. For a SIB patient with a CE lesion 10 months after proton therapy, PVR sparing treatment planning was performed.

For the SFC and UD patient cohort, the observed CE lesions clustered in direct proximity to the cerebral ventricles with median distances of 2.6 mm and 2.3 mm, respectively. Mean dose at the CE lesion was 54.4±3.5 Gy(RBE) and 56.4±4.3 Gy(RBE) and the corresponding LET value 2.7±0.4 keV/µm and 3.2±0.9 keV/µm, respectively. The SFC reduced V100% and V90% in the PVR by 11.3% and 35.3%, respectively. No significant difference was found in one-year symptomatic (p = 0.15) and asymptomatic (p = 0.75) injury free survival. An average CE lesion dose of 55 Gy(RBE) was derived within PVR tissue for all patients and used as PVR tolerance dose. Incorporating the PVR as OAR in treatment plan optimization reduced the V55Gy within the CE lesion and PVR contour by 19.1% and 2.0%, respectively, without compromising target coverage, plan robustness or clinical dose constrains (Fig. 1).

For both treatment concepts, late brain injury showed a remarkably similar proximity to the cerebral ventricles and dependence on dose and LET. The SFC spares parts of the PVR from high dose and has the potential to improve treatment outcome. However, significant reduction of brain toxicity may require a dedicated PVR dose sparing planning strategy minimizing V55Gy.

Keywords: Proton therapy; Gliomas; Normal brain tissue toxicity

  • Contribution to proceedings
    ESTRO 39, 03.-07.04.2020, Vienna, Austria
    ESTRO39 abstract book

Permalink: https://www.hzdr.de/publications/Publ-29790


Engineering Self-Supported Noble Metal Foams Toward Electrocatalysis and Beyond

Du, R.; Jin, X.; Hübner, R.; Fan, X.; Hu, Y.; Eychmüller, A.

Abstract

Noble metals, despite their expensiveness, display irreplaceable roles in widespread fields. To acquire novel physicochemical properties and boost the performance-to-price ratio for practical applications, one core direction is to engineer noble metals into nanostructured porous networks. Noble metal foams (NMFs), featuring self-supported, 3D interconnected networks structured from noble-metal-based building blocks, have drawn tremendous attention in the last two decades. Inheriting structural traits of foams and physicochemical properties of noble metals, NMFs showcase a variety of interesting properties and impressive prospect in diverse fields, including electrocatalysis, heterogeneous catalysis, surface-enhanced Raman scattering, sensing and actuation, etc. A number of NMFs have been created and versatile synthetic approaches have been developed. However, because of the innate limitation of specific methods and the insufficient understanding of formation mechanisms, flexible manipulation of compositions, structures, and corresponding properties of NMFs are still challenging. Thus, the correlations between composition/structure and properties are seldom established, retarding material design/optimization for specific applications. This review is devoted to a comprehensive introduction of NMFs ranging from synthesis to applications, with an emphasis on electrocatalysis. Challenges and opportunities are also included to guide possible research directions in this field and promote the interest of interdisciplinary scientists.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29789


Identical pion intensity interferometry at sqrt(s_NN)=2.4 GeV

Adamczewski-Musch, J.; Arnold, O.; Behnke, C.; Belounnas, A.; Belyaev, A.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Chlad, L.; Deveaux, C.; Dreyer, J.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Filip, P.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gernhäuser, R.; Golubeva, M.; Greifenhagen, R.; Guber, F.; Gumberidze, M.; Harabasz, S.; Heinz, T.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Kämpfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kornas, F.; Kotte, R.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Mangiarotti, A.; Markert, J.; Matulewicz, T.; Maurus, S.; Metag, V.; Michel, J.; Mihaylov, D. M.; Morozov, S.; Müntz, C.; Münzer, R.; Naumann, L.; Nowakowski, K.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petukhov, O.; Piasecki, K.; Pietraszko, J.; Przygoda, W.; Ramos, S.; Ramstein, B.; Reshetin, A.; Rodriguez-Ramos, P.; Rosier, P.; Rost, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schuldes, H.; Schwab, E.; Scozzi, F.; Seck, F.; Sellheim, P.; Selyuzhenkov, I.; Siebenson, J.; Silva, L.; Sobolev, Y. G.; Spataro, S.; Spies, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Szala, M.; Tlusty, P.; Traxler, M.; Tsertos, H.; Usenko, E.; Wagner, V.; Wendisch, C.; Wiebusch, M. G.; Wirth, J.; Wójcik, D.; Zanevsky, Y.; Zumbruch, P.

Abstract

High-statistics π−π− and π+π+ femtoscopy data are presented for Au+Au collisions at sqrt(s_NN)=2.4 GeV, measured with HADES at SIS18/GSI. The experimental correlation functions allow the determination of the space-time extent of the corresponding emission sources via a comparison to models. The emission source, parametrized as three-dimensional Gaussian distribution, is studied in dependence on pair transverse momentum, azimuthal emission angle with respect to the reaction plane, collision centrality and beam energy. For all centralities and transverse momenta, a geometrical distribution of ellipsoidal shape is found in the plane perpendicular to the beam direction with the larger extension perpendicular to the reaction plane. For large transverse momenta, the corresponding eccentricity approaches the initial eccentricity. The eccentricity is smallest for most central collisions, where the shape is almost circular. The magnitude of the tilt angle of the emission ellipsoid in the reaction plane decreases with increasing centrality and increasing transverse momentum. All source radii increase with centrality, largely exhibiting a linear rise with the number of participants, irrespective of transverse momentum. A substantial charge-sign difference of the source radii is found, appearing most pronounced at low transverse momentum. The extracted source parameters are consistent with the extrapolation of their energy dependence down from higher energies.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29788


Versatile Bispidine-based Bifunctional Chelators for 64CuII-Labelling of Biomolecules

Singh, G.; Zarschler, K.; Hunoldt, S.; Santana Martinez, I. I.; Rühl, C.; Matterna, M.; Bergmann, R.; Mathe, D.; Hegedüs, N.; Bachmann, M.; Comba, P.; Stephan, H.

Abstract

Bifunctional chelators as parts of modular metal-based radiopharmaceuticals are responsible for stable complexation of the radiometal ion and for covalent linkage between the complex and the targeting vector. To avoid loss of complex stability, the bioconjugation strategy should not interfere with the radiometal chelation by occupying coordinating groups. The C9 position of the very stable CuII chelator 3,7-diazabicyclo[3.3.1]nonane (bispidine) is virtually predestined to introduce functional groups for facile bioconjugation as this functionalisation does not disturb the metal binding centre. We describe the preparation and characterisation of a set of novel bispidine derivatives equipped with suitable functional groups for diverse bioconjugation reactions, including common amine coupling strategies (bispidine-isothiocyanate) and the Cu-free strain promoted alkyne-azide cycloaddition. We demonstrate their functionality and versatility in an exemplary way by conjugation to an antibody-based biomolecule and validate the obtained conjugate in vitro and in vivo.

Keywords: bispidines; bifunctional chelator; site-specific labelling; imaging; EGFR

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-29787


Ultrasmall silicon nanoparticles as a promising platform for multimodal imaging

Singh, G.; Ddungu, J. L. Z.; Licciardello, N.; Bergmann, R.; de Cola, L.; Stephan, H.

Abstract

Bimodal systems for nuclear and optical imaging are currently being intensively investigated due to their comparable detection sensitivity and complementary information they provide. In this perspective, we have implemented both modalities on biocompatible ultrasmall silicon nanoparticles (Si NPs). Such nanoparticles are particularly interesting since highly biocompatible, covalent surface functionalization and demonstrated a very fast body clearance. We prepared monodisperse citrate-stabilized Si NPs (2.4 ± 0.5 nm) with more than 40 accessible terminal amino groups per particle and, for the first time, simultaneously a near-infrared dye (IR800-CW) and a radiolabel (64Cu-NOTA = 1,4,7-triazacyclononane-1,4,7-triacetic acid) have been covalently linked to the surface of such Si NPs. The obtained nanomaterials have been fully characterized them by HR-TEM, XPS, UV-Vis and FT-IR spectroscopy. These dual-labelled particles do not exhibit any cytotoxicity in vitro. In vivo studies employing both positron emission tomography (PET) and optical imaging (OI) techniques revealed a rapid renal clearance of dual-labelled Si NPs from mice.

Involved research facilities

  • PET-Center

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29786


Updates on the FLUKA geometry for the MU2E experiment

Müller, S.; Ferrari, A.; Rachamin, R.

Abstract

Presentation at Mu2e Collaboration Meeting 16.10.2019

Keywords: Mu2e; FLUKA; Monte Carlo; CLFV

  • Lecture (Conference)
    Mu2e Collaboration Meeting, 16.-19.10.2019, Fermilab, Batavia, USA

Permalink: https://www.hzdr.de/publications/Publ-29784


Synthesis and cyclooxygenase inhibition of sulfonamide-substituted (dihydro)pyrrolo[3,2,1-hi]indoles and their potential prodrugs

Laube, M.; Gassner, C.; Knieß, T.; Pietzsch, J.

Abstract

Non-invasive imaging of cyclooxygenase-2 (COX-2) by radiolabeled ligands is attractive for the diagnosis of cancer and novel highly affine leads with optimized pharmacokinetic profile are of high interest for future developments. Recent findings have shown that methylsulfonyl-substituted (dihydro)pyrrolo[3,2,1-hi]indoles represent highly potent and selective COX-2 inhibitors but possess unsuitable pharmacokinetic properties for radiotracer applications. Based on these results, we herein present the development and evaluation of a second series of sulfonamide-substituted (dihydro)pyrrolo[3,2,1-hi]indoles and their conversion into the respective more hydrophilic N-propionamide-substituted analogs. In comparison to the methylsulfonyl-substituted leads, COX inhibition potency and selectivity was retained in the sulfonamide-substituted compounds; however, the high lipophilicity might hinder their future use. The N-propionamide-substituted analogs showed a significantly decreased lipophilicity and, as expected, lower or no COX-inhibition potency. Hence, the N-(sulfonyl)propionamides can be regarded as potential prodrugs, which represents a potential approach for more sophisticated radiotracer developments.

Keywords: Cancer; Imaging; Inflammation; Lipophilicity; McMurry cyclization; Structure-Activity-Relationship

Permalink: https://www.hzdr.de/publications/Publ-29783


Characterization of Tissue Transglutaminase as a Potential Biomarker for Tissue Response toward Biomaterials

Hauser, S.; Wodtke, R.; Tondera, C.; Wodtke, J.; Neffe, A. T.; Hampe, J.; Lendlein, A.; Löser, R.; Pietzsch, J.

Abstract

Tissue transglutaminase (TGase 2) is proposed to be important for biomaterial−tissue interactions due to its
presence and versatile functions in the extracellular environment. TGase 2 catalyzes the cross-linking of proteins through its Ca2+-dependent acyltransferase activity. Moreover, it enhances the interactions between fibronectin and integrins, which in turn mediates the adhesion, migration, and motility of the cells. TGase 2 is also a key player in the pathogenesis of fibrosis. In this study, we investigated whether TGase 2 is present at the biomaterial−tissue interface and might serve as an informative biomarker for the visualization of tissue response toward gelatin-based biomaterials. Two differently cross-linked hydrogels were used, which were obtained by the reaction of gelatin with lysine diisocyanate ethyl ester. The overall expression of TGase 2 by endothelial cells, macrophages, and granulocytes was partly influenced by contact to the hydrogels or their degradation products, although no clear correlation was evidenced. In contrast, the secretion of TGase 2 differed remarkably between the different cells, indicating that it might be involved in the cellular reaction toward gelatin-based hydrogels. The hydrogels were implanted subcutaneously in immunocompetent, hairless SKH1-Elite mice. Ex vivo immunohistochemical analysis of tissue sections over 112 days revealed enhanced expression of TGase 2 around the hydrogels, in particular at days 14 and 21 post-implantation. The incorporation of fluorescently labeled cadaverine derivatives for the detection of active TGase 2 was in accordance with the results of the expression analysis. The presence of an irreversible inhibitor of TGase 2 led to attenuated incorporation of the cadaverines, which verified the catalytic action of TGase 2. Our in vitro and ex vivo results verified TGase 2 as a potential biomarker for tissue response toward gelatin-based hydrogels. In vivo, no TGase 2 activity was detectable, which is mainly attributed to the unfavorable physicochemical properties of the cadaverine probe used.

Keywords: extracellular matrix modifying enzymes; gelatin-based hydrogels; biomaterial−tissue interface; polyamines; optical imaging

Downloads

  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-29782


Accuracy and robustness of 4D logfile-based dose reconstruction

Spautz, S.; Peters, N.; Meijers, A.; Jakobi, A.; Knopf, A.; Troost, E. G. C.; Richter, C.; Stützer, K.

Abstract

Introduction: We plan to use 4D logfile-based dose reconstruction for daily monitoring and potential intervention in PBS treatments of non-small cell lung cancer patients, restricted to limited motion (≤5mm). Here, we assessed the validity of reconstructed doses and their sensitivity to selected disturbed input parameters by dedicated phantom experiments.
Material/Methods: Quasi-monoenergetic proton fields were delivered to a dynamic thorax phantom (G.C. Technology, Germany) equipped with a 3cm soft-tissue target intersected by a radiochromic film. The surrogate signal (AZ733-V, ANZAI Medical Co.,Ltd, Japan) of the motion patterns (cos/cos4, period: 5s, peak-to-peak amplitude: 5mm and 30mm) was recorded in synchronization with the machine logfiles. 4D reconstructions with 1mm/3mm dose grid resolution were performed using 4DCTs of 12 amplitude-sorted phases and either ground truth or automatically generated deformation vector fields. Characteristic 1D profiles of the reconstructed and measured doses were compared by gamma index analyses (2mm, 2%). Maximum dose deviations due to simulated offsets between motion and machine logfiles (±1/±5/±25/±250ms) were assessed for quasi-monoenergetic and 4D optimized plans.
Results: Characteristic dose patterns were well reproduced (Fig.1). Gamma pass rates were >98% under static conditions. For 5mm motion, the pass rate of 94.2% for an ideal reconstruction with 1mm³ dose voxels dropped to 93.0% with clinically used voxel sizes (3×3×3mm³), 83.6% when using automated DIR and 78.2% for the combination of both, respectively. For the 30mm motion, the CT artifacts and residual motion were predominant and lead for 3mm dose grids to gamma pass rates of approximately 84%, irrespective of chosen DIR. Fig.2 depicts the effect of simulated logfile asynchrony.
Conclusions: The implemented method is robust against disturbed input parameters for the small, clinically aimed motion amplitudes. Reconstruction accuracy decreases with deformation-related inaccuracies and increasing 4DCT artifacts for large motion. Consistent breathing and regular control CTs are compulsory for meaningful 4D logfile-based dose reconstructions.

  • Poster
    4D Treatment Workshop for Particle Therapy 2019, 22.-23.11.2019, Kraków, Polska

Permalink: https://www.hzdr.de/publications/Publ-29781


Search for beta-delayed proton emission from ¹¹Be

Riisager, K.; Borge, M. J. G.; Briz, J. A.; Carmona-Gallardo, M.; Forstner, O.; Fraile, L. M.; Fynbo, H. O. U.; Garzon Camacho, A.; Johansen, J. G.; Jonson, B.; Lund, M. V.; Lachner, J.; Madurga, M.; Merchel, S.; Nacher, E.; Nilsson, T.; Steier, P.; Tengblad, O.; Vedia, V.

Abstract

We report on an attempt to reproduce the observation of beta-minus-delayed proton emission from ¹¹Be through detection of the final state nucleus ¹⁰Be with accelerator mass spectrometry. Twelve samples were collected at the ISOLDE facility at CERN at different separator settings, allowing tests of different sources of contamination to be carried out. The observed amounts of ¹⁰Be per collected ¹¹Be rule out several contamination sources, but do not agree internally. Formation of BeH molecular ions in the ion source may explain our data, in which case an upper limit of the beta p branching ratio of 2.2 x10-6 can be derived.

Keywords: beta-decay; AMS

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29780


A Simulation-Based Study on Reprocessing of Phosphate Tailings for Recovering Pyrochlore and Monazite

Vicino Pacheco De Aquino, T.; Pereira, L.; Hassanzadehmahaleh, A.; Belo Fernandes, I.; Rudolph, M.; Mischo, H.; Barakos, G.

Abstract

The present study aims to investigate possibilities for improving the recovery of pyrochlore ((Na, Ca)₂Nb₂O₆) and monazite ((Ce, La, Th, Sm)PO4) as by-products from a phosphate mine with current niobium (Nb) production from geometallurgical perspectives. With this purpose, process mineralogy of Nb- and REE-bearing minerals together with operating properties of the concentration plant are examined using respectively mineral liberation analyzer (MLA) and the HSC® Chemistry 9 simulation module. A plant-site sampling campaign was performed and key operating parameters such as throughputs and pulp densities for individual streams were measured. The results obtained by MLA analyses as the base of mineral mass balances were compared and validated by commonly used chemical characterization techniques i.e. X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma–optical emission spectroscopy (ICP-OES). Simulation results showed that the combination of Nb flotation rougher and scavenger cells into one single rougher bank plus the addition of a new scavenger bank (4x1.4 m³ cells) can increase pyrochlore recovery in the silica/niobium flotation circuit from approximately 31% to 44%. This cell configuration improves the ultimate pyrochlore’s plant recovery from 27% to 38% leading to a substantial enhancement in final concentrate throughput from 540 to 740 kg/h. Future studies on this topic include the use of wet high intensity magnetic separation (WHIMS) and froth flotation respectively for the pre-concentration and concentration of monazite.

Keywords: Pyrochlore; phosphate deposit; rare earth elements (REE); HSC Sim®; process simulation

  • Contribution to proceedings
    International Mineral Processing Conference Eurasia (IMPC 2019), 31.10.-02.11.2019, Antalya, Turkey
    Proceedings of IMPC 2019

Permalink: https://www.hzdr.de/publications/Publ-29779


⁹⁹Tc immobilization by aluminum solids containing Fe(II) moieties

Mayordomo, N.; Rodriguez Hernandez, D. M.; Molodtsov, K.; Johnstone, E. V.; Roßberg, A.; Heim, K.; Foerstendorf, H.; Schild, D.; Brendler, V.; Müller, K.

Abstract

The immobilization of ⁹⁹Tc is predominantly mediated by the reduction of Tc(VII) to Tc(IV), primarily due to the fact that [Tc(VII)O₄] ⁻ interactions with solid interfaces are limited, whereas Tc(IV)O₂ is a hardly soluble solid [1]. Tc reduction is facilitated by Fe²⁺, particularly when it is present as a sorbed species or a constituent mineral phase [2].
The present work analyzes the ⁹⁹Tc aqueous removal by two aluminum solids containing Fe(II) moieties: γ-Al₂O₃ with sorbed Fe²⁺ and Fe(II)-Al(III) layered double hydroxide (LDH). Batch contact experiments demonstrate that both solids are effective Tc scavengers, yielding a complete removal for pH > 6.5 and from pH 3.5 to 10.5, respectively. Characterization via XPS, XAS, and in situ ATR FT-IR spectroscopy provided information of the Tc speciation and uptake mechanism. Secondary Fe-minerals (hematite, magnetite, ferrihydrite) formed in the reduction were also identified by Raman microscopy.

Bibliography
[1] Meena, A. H.; Arai, Y. Env. Chem Lett 2017, 15, 241–263.
[2] Cui, D.; Eriksen, T. E. Environ. Sci. Technol. 1996, 30 (7), 2259–2262.

  • Lecture (Conference)
    The 43th symposium on scientific basis for nuclear waste management, 21.-24.10.2019, Viena, Austria

Permalink: https://www.hzdr.de/publications/Publ-29778


Some microbial issues regarding the storage of high-level radioactive waste

Matschiavelli, N.; Kluge, S.; Dressler, M.; Cherkouk, A.

Abstract

The talk summerizes bio-geochemical results regarding the potential geo-technical barrier bentonite in a repositors of high-level radioactive waste.

  • Lecture (others)
    18th bilateral meeting HZDR/IRE - PSI/LES, 28.-29.10.2019, HZDR, IRE, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29777


Nonstoichiometric Phases of Two-Dimensional Transition-Metal Dichalcogenides: From Chalcogen Vacancies to Pure Metal Membranes

Joseph, T.; Ghorbani Asl, M.; Kvashnin, A. G.; Larionov, K. V.; Popov, Z. I.; Sorokin, P. B.; Krasheninnikov, A.

Abstract

Two-dimensional (2D) membranes consisting of a single layer of Mo atoms were recently manufactured [ Adv. Mater. 2018, 30, 1707281] from MoSe2 sheets by sputtering Se atoms using an electron beam in a transmission electron microscope. This is an unexpected result as formation of Mo clusters should energetically be more favorable. To get microscopic insights into the energetics of realistic Mo membranes and nonstoichiometric phases of transition-metal dichalcogenides (TMDs) MaXb, where M = Mo and W and X = S, Se, and Te, we carry out first-principles calculations and demonstrate that the membranes, which can be referred to as metallic quantum dots embedded into a semiconducting matrix, can be stabilized by charge transfer. We also show that an ideal neutral 2D Mo or W sheet is not flat but a corrugated structure, with a square lattice being the lowest-energy configuration. We further demonstrate that several intermediate nonstoichiometric phases of TMDs are possible as they have lower formation energies than pure metal membranes. Among them, the orthorhombic metallic 2D M4X4 phase is particularly stable. Finally, we study the properties of this phase in detail and discuss how it can be manufactured by the top-down approaches.

Keywords: 2D; non-stoichiometric phases; Transition-Metal Dichalcogenides; DFT; metal membrane

Involved research facilities

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29776


Thickness of polyelectrolyte layers of separately confined bacteria alters key physiological parameters on a single cell level

Rybkin, I.; Gorin, D.; Sukhorukov, G.; Lapanje, A.

Abstract

Confinement of bacterial cells in matrix or capsules is an integral part of many biotechnological applications. Here, it is adopted the well-known layer-by-layer method of deposition of a few nanometer thick polyelectrolyte layers to confine separated bacterial cells in permeable and physically durable shells. Due to the physical properties of such a confinement, here it is found that this method enables investigation of effects of physical barrier against the mass gain and cell division. Using the method of time-lapse confocal microscopy, it is observed a prolonged lag phase, dependent on the number of polyelectrolyte layers. In the confinement, both the GFP fluorescent signal from the leaking T7 promoter and cell size, were increased by more than five and two times, respectively. This creates paradigm shift that enables using mechanical entrapment for control of bacterial cell physiology which opens possibilities of controlling the division rate as well as gene expression. These effects can be attributed to the perturbation of the sensing of the cell size, which results in disproportional synthesis of cell envelope against the intracellular material and compels cells to grow rapidly. In addition, the charged surface of cells enabled longer intercellular physical interaction resulting in spherically shaped microcolonies.

Keywords: time-lapse confocal microscopy; polyelectrolytes; layer-by-layer encapsulation; electrostatic interactions; cell surface modification

Permalink: https://www.hzdr.de/publications/Publ-29775


M4F - Materials Modelling For Fusion and Fission Materials - Domain 1

Heintze, C.; Olsson, P.; Konstantinovic, M.; Caturla, M.-J.

Abstract

The talk provides on overview on the objectives, activities and first results of Domain 1 of the H2020/EU project M4F. It aims at providing a broader scientific motivation and background for the benefit of the PhD students and post-docs participating in the project.

  • Lecture (others)
    M4F PhD and post-doc event, 23.-25.06.2019, Miraflores de la Sierra, Madrid, Spain

Permalink: https://www.hzdr.de/publications/Publ-29774


Behaviour of C, Ni, Si, P under ion irradiation at different doses in model FeCr(Ni, Si, P) alloys

Gueye, P.-M.; Gomez-Ferrer, B.; Heintze, C.; Pareige, C.

Abstract

Ferritic-martensitic steels with high chromium content are considered as promising candidates as structural materials in Gen-IV reactors because of their low swelling value for operating conditions and low ductile-brittle transition temperature (DBTT) shift under irradiation. Nevertheless, they tend to harden and embrittle under irradiation at low temperatures (350°C). Impurities as Ni, Si and P are known to increase hardening in these steels by creating solute-rich clusters (SRCs) [1-4].
In order to understand the role of each impurity on the formation of SRCs under irradiation, FeCr (NiSiP) alloys with different concentrations in Ni, Si and P have been ion irradiated with 5 MeV Fe2+ ions up to 0.1, 0.5 and 2.5 dpa at 300°C. The evolution of the solute distribution has been investigated by atom probe tomography (APT).
The results reveal the tendency to cluster of Ni, Si and P under irradiation from 0.1 dpa. Moreover, differences on the solutes distributions between materials containing one low-alloying element (Ni, Si or P) and the alloy containing Ni, Si and P, suggest a synergetic effect between these species. Results show the major role of P on the formation of the SRCs. The influence of C on the formation of SRCs will also be discussed.

References
[1] F. Garner, M. Toloczko, B. Sencer, J. Nucl. Mater. 276 (2000) 123.
[2] R. L. Klueh, A. T. Nelson, J. Nucl. Mater. 371 (2007) 37-52.
[3] A. Kohyama, A. Hishinuma, D. S. Gelles, R. L. Klueh, W. Dietz, K. Ehrlich, J. Nucl. Mater. 233-237 (1996) 138-147.
[4] B. Gomez-Ferrer, C. Heintze, C. Pareige, J. Nucl. Mater. 515 (2019) 35-44.

Involved research facilities

Related publications

  • Lecture (others)
    M4F PhD and post-doc event, 23.-25.06.2019, Miraflores de la Sierra, Madrid, Spain

Permalink: https://www.hzdr.de/publications/Publ-29773


On the role of Ni, Si and P on the nanostructural evolution of FeCr alloys under irradiation – link with hardening

Pareige, C.; Gómez-Ferrer, B.; Heintze, C.; Oñorbe, E.; Hernandez-Mayoral, M.; Desgardin, P.; Malerba, L.

Abstract

High-chromium ferritic-martensitic (F-M) steels are promising candidates for structural components in Gen-IV reactors because of their excellent swelling resistance and good thermal properties. However, the operating window of these steels is constrained by irradiation hardening at low temperature (<350°C). This issues has been addressed within the FP7/MatISSE project.
After neutron irradiation of Fe-Cr alloys of low purity (model alloys of F-M steels), impurities as P, Ni and Si have been shown to create solute clusters which significantly contribute to hardening and might be associated with small invisible dislocation loops1. In order to understand the role of each impurity on the formation of the nano-features formed under irradiation and the eventual synergies between the different species, FeCr(SiNiP) alloys of different composition has been ion irradiated and characterized using transmission electron microscopy, atom probe tomography, positron annihilation and nano-indentation. Combination of these techniques enabled to study the influence of these impurities on the concentration of vacancy defects, formation of solute clusters and dislocation loops and to make the link with irradiation hardening.

Involved research facilities

Related publications

  • Lecture (Conference)
    SMINS 5 - NEA International Workshop on Structural Materials for Innovative Nuclear Systems, 08.-11.07.2019, Kyoto, Japan

Permalink: https://www.hzdr.de/publications/Publ-29772


Influence of impurities in microstructural evolution of FeCr alloys under ion irradiation – link with hardening

Pareige, C.; Gómez-Ferrer, B.; Heintze, C.; Onorbe, E.; Hernándet Mayoral, M.; Gueye, P.-M.; Malerba, L.

Abstract

After neutron irradiation of Fe-Cr alloys of low purity (model alloys of F-M steels), impurities as P, Ni and Si have been shown to create solute clusters which significantly contribute to hardening and might be associated with small dislocation loops. In order to understand the role of each impurity on the formation of the nano-features formed under irradiation and the eventual synergies between the different species, FeCr(SiNiP) alloys of different composition have been ion irradiated and characterized using transmission electron microscopy, atom probe tomography and nano-indentation. Combination of these techniques enabled to study the influence of these impurities on the formation of solute clusters and dislocation loops and to make the link with irradiation hardening. Influence of C atoms on the nanostructure evolution will also be discussed.

Involved research facilities

Related publications

  • Lecture (Conference)
    MINES - Materials in Nuclear Energy Systems, 06.-10.10.2019, Baltimore, Maryland, USA

Permalink: https://www.hzdr.de/publications/Publ-29771


Neutron irradiated microstructure of FeCr alloys investigated by TEM

Hernández Mayoral, M.; Onorbe, E.; Gómez-Ferrer, B.; Heintze, C.; Malerba, L.; Gueye, P.-M.; Pareige, C.

Abstract

Different parameters have been observed to influence the nature and evolution of the neutron radiation induced features, which are responsible of the mechanical behavior of FeCr-based alloys. In this work, the experimental conditions were selected so as to focus on the effect of both, composition and irradiation temperature. The study has been performed in the framework of collaborative European funded projects, where a combination of advanced characterization techniques was applied to a set of alloys of varying composition and initial microstructure, which were irradiated together under different conditions of temperature, dose and also dose-rate. The characterization of dislocation loops has been performed on the basis of Transmission Electron Microscopy (TEM), while the solute redistribution has been studied by Atom Probe Tomography (APT). The results, that show how the involved variables affect the neutron irradiated microstructure, will be presented and discussed.

  • Lecture (Conference)
    MINES - Materials in Nuclear Energy Systems, 06.-10.10.2019, Baltimore, Maryland, USA

Permalink: https://www.hzdr.de/publications/Publ-29770


Hyperspectral outcrop models for palaeoseismic studies

Kirsch, M.; Lorenz, S.; Zimmermann, R.; Andreani, L.; Tusa, L.; Pospiech, S.; Jackisch, R.; Unger, G.; Khodadadzadeh, M.; Ghamisi, P.; Middleton, M.; Ojala, A.; Mattila, J.; Nordbäck, N.; Palmu, J.-P.; Ruskeeniemi, T.; Sutinen, R.; Tiljander, M.; Heikkilä, P.; Gloaguen, R.

Abstract

The traditional study of palaeoseismic trenches, involving logging, stratigraphic and structural interpretation, can be time consuming and affected by biases and inaccuracies. To overcome these limitations, a new workflow is presented that integrates infrared hyperspectral and photogrammetric data to support field-based palaeoseismic observations. As a case study, this method is applied on two palaeoseismic trenches excavated across a post-glacial fault scarp in northern Finnish Lapland. The hyperspectral imagery (HSI) is geometrically and radiometrically corrected, processed using established image processing algorithms and machine learning approaches, and co-registered to a structure-from-motion point cloud. HSI-enhanced virtual outcrop models are a useful complement to palaeoseismic field studies as they not only provide an intuitive visualisation of the outcrop and a versatile data archive, but also enable an unbiased assessment of the mineralogical composition of lithologic units and a semi-automatic delineation of contacts and deformational structures in a 3D virtual environment.

Keywords: palaeoseismology; SfM photogrammetry; hyperspectral imaging; geology; remote sensing; outcrop models

Permalink: https://www.hzdr.de/publications/Publ-29768


Neutron Transmission Measurements at nELBE

Junghans, A.; Beyer, R.; Claußner, J.; Kögler, T.; Urlaß, S.; Bemmerer, D.; Ferrari, A.; Schwengner, R.; Wagner, A.; Dietz, M.; Frotscher, A.; Grieger, M.; Hensel, T.; Koppitz, M.; Ludwig, F.; Turkat, S.; Nolte, R.; Pirovano, E.; Kopecky, S.; Nyman, M.; Plompen, A.; Schillebeeckx, P.; Borris, E.; Reifarth, R.; Veltum, D.; Weigand, M.; Glorius, J.; Görres, J.; Oberlack, U.; Wenz, D.

Abstract

Neutron total cross sections are an important source of experimental data in the evaluation of neutroninduced cross sections. The sum of all neutron-induced reaction cross sections can be determined with a precision of a few per cent in a relative measurement. The neutron spectrum of the photoneutron source nELBE extends in the fast region from about 100 keV to 10 MeV and has favourable conditions for transmission measurements due to the low instantaneous flux of neutrons and low gamma-flash background. Several materials of interest (in part included in the CIELO evaluation or on the HPRL of OECD/NEA) have been investigated: 197Au [1, 2], natFe [2], natW [2], 238U, natPt, 4He, natO, natNe, natXe. For gaseous targets high pressure gas cells with flat end-caps have been built that hold up to 200 bar pressure. The experimental setup will be presented including results from several transmission experiments and the data analysis leading to the total cross sections will be discussed

Keywords: neutron total cross sections; He; Ne; O; Xe; Pt; 238U; nELBE time of flight faciltiy; transmission measurement

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29767


Direct Synthesis of Large-Scale Multilayer TaSe2 on SiO2/Si Using Ion Beam Technology

Tsai, H.-S.; Liu, F.-W.; Liou, J.-W.; Chi, C.-C.; Tang, S.-Y.; Wang, C.; Ouyang, H.; Chueh, Y.-L.; Liu, C.; Zhou, S.; Woon, W.-Y.

Abstract

The multilayer 1T-TaSe2 is successfully synthesized by annealing a Se-implanted Ta thin film on the SiO2/Si substrate. Material analyses confirm the 1T (octahedral) structure and the quasi-2D nature of the prepared TaSe2. Temperaturedependent resistivity reveals that the multilayer 1T-TaSe2 obtained by our method undergoes a commensurate charge-density wave (CCDW) transition at around 500 K. This synthesis process has been applied to synthesize MoSe2 and HfSe2 and expanded for synthesis of one more transition-metal dichalcogenide (TMD) material. In addition, the main issue of the process, that is, the excess metal capping on the TMD layers, is solved by the reduction of thickness of the as-deposited metal thin film in this work.

Keywords: TaSe2; charge-density wave; ion beam; synthesis

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29766


Production of the amphiphilic siderophore Marinobactin for the application as froth flotation reagent. 

Schrader, S.; Kutschke, S.; Rudolph, M.; Pollmann, K.

Abstract

The consumption of metallic raw materials increased in the last years. The coverage of demand is getting more difficult, because both primary and secondary raw materials become more and more complex. To find a solution, some new ways have to be gone, like the combination of biotechnology with classic processing methods.
The idea of this work is the biotechnological production of siderophores for the application as a reagent in the classic froth flotation process. Siderophores are small organic molecules with a high affinity for binding Fe(III) and to form strong complexes also with other metals. They are produced by microorganisms (aerobic bacteria and fungi) and some plants. Especially the group of amphiphilic siderophores are very interesting. The hydrophilic part, carrying hydroxamate groups, is responsible for the binding of the metals. Flotation agents produced by the chemical industry with the same functional groups have already been applied successfully in this processing method. It can be suggested siderophores carrying the same functional groups, also work well as collectors. The fatty acid tail, that is representing the hydrophobic part, gets in contact with the bubble and spares additional chemicals and further working steps for making the target mineral particles hydrophobic.
Besides the biotechnological production of these amphiphilic siderophores, this work presents interaction studies and flotation experiments of different scales, including “Bubble pick up test”, Halimond tube tests and one-liter flotation experiments of iron, copper and PGM containing ores.
The application of amphiphilic siderophores as biochemicals in the froth flotation process can change the classic processing method in a more sustainable process – the Bioflotation process. This will reduce the usage of other chemical agents. Moreover, the specific metal binding of siderophores changes flotation in a more purposeful and efficient process and is an important enrichment for the field of Biohydrometallurgy.

Keywords: Marinobactin; Marinobacter; amphiphilic; Siderophores froth flotation

  • Lecture (Conference)
    23. International Biohydrometallurgy Symposium, 20.10.2019, Fukuoka, Japan

Permalink: https://www.hzdr.de/publications/Publ-29765


Amphiphilic Siderophores – A group of complexing surfactant bioreagents for the application in froth flotation separation

Schrader, S.; Kutschke, S.; Hartmann, S.; Pollmann, K.; Rudolph, M.

Abstract

The consumption of metallic raw materials is constantly increasing. The coverage of demand is getting more difficult, because both primary and secondary raw materials become more and more complex. To find a solution, new approaches will have to be developed, like the combination of biotechnology with classic processing methods.
The idea of this work is the biotechnological production of siderophores for the application as a reagent in conventional froth flotation processes. Siderophores are small organic molecules with a high affinity for binding Fe(III) and to selectively form strong complexes also with other metals. They are produced by microorganisms (aerobic bacteria and fungi) and some plants. Especially the group of amphiphilic siderophores are very interesting. The hydrophilic part, carrying hydroxamate functional groups, is responsible for the selective binding of the metals. Flotation agents produced by the chemical industry with the same functional groups have already been applied successfully in this processing method. It can be suggested siderophores carrying the same and even more selective functional groups are highly potential as ecofriendly collector molecules for flotation and should generally be interesting for the surfactant industry. The molecule’s tail, that is representing the hydrophobic part, gets in contact with the bubble and spares additional chemicals and further working steps for making the target mineral particles hydrophobic.
Besides the biotechnological production of these amphiphilic siderophores, this work includes also interaction studies and flotation experiments of different scales, including bubble pick-up tests, Halimond tube microflotation and batch lab flotation experiments of iron and copper bearing ores.
The application of amphiphilic siderophores as biochemicals in the froth flotation process can change the classic processing method in a more sustainable process – the Bioflotation process. This will reduce the usage of other chemical agents. Moreover, the specific metal binding of siderophores changes flotation in a more purposeful and efficient process and is an important enrichment for the field of Biohydrometallurgy.

Keywords: Marinobactin; Marinobacter; amphiphilic; Siderophores froth flotation

  • Poster
    Jahrestreffen der ProcessNet-Fachgruppen Zerkleinern und Klassieren, Kristallisation und Grenzflächenbestimmte Systeme und Prozesse, 12.-13.03.2019, Bamberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29764


Production of the amphiphilic siderophore marinobactin and the application as froth flotation reagent

Schrader, S.; Kutschke, S.; Rudolph, M.; Pollmann, K.

Abstract

The consumption of metallic raw materials increased in the last years. The coverage of demand is getting more difficult, because both primary and secondary raw materials become more and more complex. To find a solution, some new ways have to be gone, like the combination of biotechnology with classic processing methods.
The idea of this work is the biotechnological production of siderophores for the application as a reagent in the classic froth flotation process. Siderophores are small organic molecules with a high affinity for binding Fe(III) and to form strong complexes also with other metals. They are produced by microorganisms (aerobic bacteria and fungi) and some plants. Especially the group of amphiphilic siderophores are very interesting. The hydrophilic part, carrying hydroxamate groups, is responsible for the binding of the metals. Flotation agents produced by the chemical industry with the same functional groups have already been applied successfully in this processing method. It can be suggested siderophores carrying the same functional groups, also work well as collectors. The fatty acid tail, that is representing the hydrophobic part, gets in contact with the bubble and spares additional chemicals and further working steps for making the target mineral particles hydrophobic.
Besides the biotechnological production of these amphiphilic siderophores, this work presents interaction studies and flotation experiments of different scales, including “Bubble pick up test”, Halimond tube tests and one-liter flotation experiments of iron, copper and PGM containing ores.
The application of amphiphilic siderophores as biochemicals in the froth flotation process can change the classic processing method in a more sustainable process – the Bioflotation process. This will reduce the usage of other chemical agents. Moreover, the specific metal binding of siderophores changes flotation in a more purposeful and efficient process and is an important enrichment for the field of Biohydrometallurgy.

Keywords: Marinobactin; Marinobacter; amphiphilic; Siderophores froth flotation

  • Poster
    4th Green & Sustainable Chemistry Conference, 05.-08.05.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29762


Simulation-Based Exergy and LCA Analysis of Aluminum Recycling: Linking Predictive Physical Separation and Re-melting Process Models with Specific Alloy Production

Hannula, J. O.; Da Assuncao Godinho, J. R.; Abadias Llamas, A.; Luukkanen, S.; Reuter, M.

Abstract

Recycling and process metallurgy are the main enablers of Circular Economy (CE). To assess the circularity of CE, a detailed understanding of the limits of the current recycling infrastructure is required. For this paper, a predictive physical separation model for Eddy Current Separator was developed using 3D particle-level detail acquired by Computed Tomography. The developed model was combined with re-melting and alloying models to create an aluminum recycling flowsheet in a simulation platform HSC Sim. Different simulation scenarios were considered, and the impact of the physical separation stage to resource efficiency was quantified by measuring the required additional resources to produce specific alloy types. The resource efficiency and environmental impacts were estimated through exergy analysis and Life Cycle Assessment based on the detailed physical and thermochemistry simulation models. The paper demonstrates how digitalization and exergy analysis allow more efficient use of resources in the sense of CE.

Keywords: Aluminum Recycling; Modeling; Simulation; Exergy; Circular Economy

Permalink: https://www.hzdr.de/publications/Publ-29761


Impact of range uncertainty on clinical distributions of linear energy transfer and biological effectiveness in proton therapy

Hahn, C.; Eulitz, J.; Peters, N.; Wohlfahrt, P.; Enghardt, W.; Richter, C.; Lühr, A.

Abstract

In proton radiotherapy, range uncertainties can lead to differences between the clinically approved dose and that delivered to the patient. Likewise, the linear energy transfer (LET), which drives the relative biological effectiveness (RBE), is affected by range uncertainties. Clinical robust dose optimization ensures the delivery of the prescribed dose but not of a specific LET. In this study, the impact of range uncertainties on LET distributions in clinically robust dose-optimized treatment plans was quantified and potential biological implications in patients were assessed.
For each of six cancer patients (two brain, head-and-neck and prostate), two nominal treatment plans in pencil beam scanning mode were robustly dose-optimized using single- and multi-field optimization, respectively. Scenarios with range uncertainty of ± 3.5% were achieved by global rescaling of stopping-power ratios. Dose and LET distributions were recalculated using the nominal beam parameters and used to estimate the probability of radiation-induced toxicity.
The optimization technique had a minor impact on the results. For all patients, LET distributions in the target volume were rather homogeneous with average LET below 3.2 keV/µm and only a weak impact of range uncertainty was found. In contrast, LET hotspots (> 7 keV/µm) occurred in several organs at risk (OARs). Elevated and inhomogeneous LET distributions were organ- and patient-specific for OARs susceptible to range uncertainties. The observed changes in the probability for radiation-induced toxicity depended on OAR location and range uncertainty scenario.
Range uncertainties can substantially change LET values in OARs while the observed LET variation among all patients and scenarios was small in the CTV. The present findings support a constant RBE prescription in the CTV. However, unforeseen toxicity may occur in normal tissue due to elevated and inhomogeneous LET distributions caused by range uncertainty. We encourage LET-related objectives in robust optimization and consideration of range uncertainty in RBE assessment based on patient follow-up datasets.

Keywords: proton therapy; range uncertainties; linear energy transfer (LET); biological effectiveness

Permalink: https://www.hzdr.de/publications/Publ-29760


Design and Evaluation of a STM-FPGA-DAQ-HLS-Template for the Mu2e Experiment

Knodel, O.

Abstract

Overview and status of the STM-FPGA-DAQ-HLS-Template for the Mu2e Experiment located Fermilab.

Keywords: Data Management; DAQ; FPGA; Mu2e

  • Invited lecture (Conferences)
    STM-Working Group Meeting, 09.10.2019, Batavia, United States

Permalink: https://www.hzdr.de/publications/Publ-29759


HZDR Data Management Strategy — An Overview

Knodel, O.; Müller, S.

Abstract

Overview of the HZDR data management strategy, hosted services for collaborative work and a (planned) technical realization.

Keywords: Data Management

  • Invited lecture (Conferences)
    Meeting with the Scientific Computing Division at Fermilab, 08.10.2019, Batavia, United States

Permalink: https://www.hzdr.de/publications/Publ-29758


Recent progress in application of computational chemistry to actinide interaction with biomolecules

Tsushima, S.

Abstract

Thanks to rapid advancement in computing technology, computer chemistry is becoming increasingly important in the field of biology. This approach is nowadays a common tool for drug discovery or for studying diseases such as HIV. In this talk, I will present several examples in which computer chemistry was applied for studying potential health risk of accidental ingestion of actinides and lanthanides. The new approach called “fragment molecular orbital method” has been implemented to drastically reduce computing time, which made it possible to calculate interactions of actinide/lanthanide with large biological molecules such as DNA and protein using full quantum mechanical description. In one example, how uranium ingestion could damage DNA in a molecular scale will be presented.

  • Invited lecture (Conferences)
    Engineering Physics Seminar Series at the Department of Engineering Physics of the McMaster University, 04.10.2019, Hamilton, Canada

Permalink: https://www.hzdr.de/publications/Publ-29757


Crystallization of Anhydrous Proton from Acidic Aqueous Solution with Diamide Building Block

Kazama, H.; Tsushima, S.; Takao, K.

Abstract

Although H+ has the largest hydration enthalpy amongst all the monovalent cations, we have demonstrated that anhydrous H+ can be crystallized together with selected diamide building block (L) and NO3− even in acidic aqueous solutions, which were confirmed in 3 different structures. One of these anhydrous H+ adducts constitutes of H+-involved hydrogen bond polymers [L···H+]n, which are coupled with another H+ adduct [O2NO−···H+···O−NO2]− as a counteranion unit. The anhydrous H+ can also be trapped between L and NO3− to form heteroleptic O···H+···O hydrogen bonds observed in two different crystal structures. DFT calculations revealed that there is no energetic barrier in these O···H+···O hydrogen bonds, having so-called a single-well hydrogen bond.

Permalink: https://www.hzdr.de/publications/Publ-29756


Re-mining of mine wastes in Germany: Challenges and opportunities

Büttner, P.; Nühlen, J.; Meima, J.; Gutzmer, J.

Abstract

The Fraunhofer Institute for Environmental, Safety, and Energy Technology and the Helmholtz Institute Freiberg for Resource Technology (HIF) have together compiled a mine waste cadaster for Germany on behalf of the Federal Institute for Geosciences and Natural Resources (BGR). For this purpose, a wide variety of data sources was evaluated with the aim to create a national database able to provide an overview about the content of critical raw materials (CRM) in mine waste repositories in Germany. Yet, even though mine wastes containing economically significant amounts of CRM, re-mining these anthropogenic “ore bodies” faces considerable technical and non-technical challenges.

Mine wastes often create environmental problems, such as acid rock drainage with associated high sulfate and heavy metal concentrations. This creates societal pressure for remediation. Remediation, however, is usually achieved by covering the surface with a water impermeable layer, an approach that is not sustainable, because of the required follow-up care and the inaccessibility of the resources that remain contained in the mine wastes. Besides that, legislative barriers are in conflict with recovering CRM and other metals and minerals from historic mine wastes. Many sites have essentially been abandoned since mining ceased in the 20th century. High metal contents and acidity released during sulfide oxidation has facilitated the establishment of a very specific flora and fauna. Species on these sites are often rare and strictly protected by environmental legislation. Metal recovery is all but impossible from such sites, despite the fact that acid rock drainage from these sites leads to environmental degradation downstream from the mine waste site.

Another important aspect is the general lack of suitable beneficiation and metallurgical infrastructure in Germany. Large capital investment would thus be necessary to enable the recovery of strategic metals from historic mine waste. Even if high metal concentrations are present in some mine wastes, small volumes will render the set-up of large, stationary plants unfeasible. Instead, flexible and semi-mobile small-scale technologies need to be developed. Such technologies are, at present, not available on the market.

To work at the intersection of society, legislation, remediation and re-mining is the aim of the new rECOmine partnership. This partnership is funded by the Federal Ministry of Education and Research (BMBF) for the next five years within the WIR! Program. It will be coordinated by HIF and build up three test sites in Saxony to develop combined remediation and re-mining technologies under real conditions with local partners.

Keywords: Re-Mining; Mine Waste; Resource; Tailing; Feasilbility; MLA

  • Lecture (Conference)
    GeoMünster 2019, 22.-25.09.2019, Münster, Germany

Permalink: https://www.hzdr.de/publications/Publ-29755


Dynamically Pre-Compressed Hydrocarbons Studied by Self-Impedance Mismatch

Hartley, N.; Zhang, C.; Duan, X.; Huang, L.; Jiang, S.; Li, Y.; Yang, L.; Pelka, A.; Wang, Z.; Yang, J.; Kraus, D.

Abstract

Using the SG-III prototype laser at CAEP, Mianyang, we irradiated polystyrene samples with a thermal radiation drive, reaching conditions on the principal Hugoniot up to P~1 TPa (10 Mbar), and away from the Hugoniot up to P~300 GPa (3 Mbar). The response of the samples was measured with a velocity interferometry diagnostic to determine the material and shock velocity, and hence the conditions reached, and the reflectivity of the sample, from which changes in the conductivity can be inferred. By applying the self-impedance mismatch technique with the measured velocities, the pressure and density of thermodynamic points away from the principal Hugoniot were determined. Our results show an unexpectedly large reflectivity at the highest shock pressures, while the off-Hugoniot points agree with previous work suggesting that CH conductivity, at least at the shock front, is primarily temperature-dependent.

Keywords: Polymers; Shock compression; Optical properties; Thermodynamic states and processes; Planetary interiors; Shock waves; Hydrodynamics simulations; Metallization process

Permalink: https://www.hzdr.de/publications/Publ-29754


⁶⁰Fe deposition during the late Pleistocene and the Holocene echoes supernova activity

Wallner, A.; Feige, J.; Fifield, K.; Froehlich, M. B.; Golser, R.; Hotchkis, M. A. C.; Koll, D.; Leckenby, G.; Martschini, M.; Merchel, S.; Panjkov, S.; Pavetich, S.; Rugel, G.; Tims, S. G.

Abstract

Nuclides synthesized in massive stars are ejected into space via their stellar winds and in supernova explosions. The Solar System moves through the interstellar medium and collects some of these nucleosynthesis products. One such product is ⁶⁰Fe, a radionuclide with 2.6 million years half-life, that is predominantly produced in massive stars and ejected in supernova explosions. Extraterrestrial ⁶⁰Fe has been found on Earth, suggesting close-by supernova explosions ~2–3 and ~6 million years ago. Here, we report on the detection of a continuous interstellar ⁶⁰Fe-influx on Earth over the past ~33,000 years. This time period coincides with passage of our Solar System through such interstellar clouds, which have a significantly larger particle density compared to the local average interstellar medium embedding our Solar System for the past few million years. The interstellar ⁶⁰Fe was extracted from five deep-sea sediment samples and accelerator mass spectrometry was used for single atom counting. Despite the low number of 19 detected atoms, owing to a low influx, the ⁶⁰Fe-deposition rate does not indicate large variations over the 33,000 years. The measured approximately constant ⁶⁰Fe-time profile does not seem to reflect any large changes in the interstellar particle density during Earth’s passage through local interstellar clouds, that could be expected if the local cloud represented an isolated remnant of the most recent Supernova ejecta that traversed the Earth ~2–3 million years ago. The identified ⁶⁰Fe influx may signal a late echo of some million-year old supernovae with the ⁶⁰Fe-bearing dust particles still permeating the interstellar medium.

Keywords: AMS; supernova

Involved research facilities

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29752


Delayed arrival of arterial blood in cortex is associated with decreased CSF levels of amyloid beta in predementia Alzheimer's disease

Palhaugen, L.; Selnes, P.; Tecelao, S.; Lysvik, E. K.; Ingala, S.; Petr, J.; Bjornerud, A.; Mutsaerts, H. J.; Fladby, T.

Abstract

Delayed arrival of arterial blood in cortex is associated with decreased CSF levels of amyloid beta in predementia Alzheimer's disease

Involved research facilities

  • PET-Center
  • Open Access Logo Contribution to proceedings
    Congress of the European Academy of Neurology, 29.06.2019, Oslo, Norway
  • Poster
    Congress of the European Academy of Neurology, 29.06.2019, Oslo, Norway

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29751


Scalable particle-in-cell simulations on many-core hardware with the free and open source code PIConGPU

Steiniger, K.; Bastrakov, S.; Cowan, T.; Debus, A.; Garten, M.; Göthel, I.; Hübl, A.; Juckeland, G.; Kelling, J.; Kluge, T.; Koßagk, S.; Matthes, A.; Pausch, R.; Schramm, U.; Starke, S.; Widera, R.; Worpitz, B.; Bussmann, M.

Abstract

Exploring new regimes, optimizing experimental setups, or quantifying sensitivity of final beam parameters on experimental parameters, represent current challenges for simulations of laser plasma accelerators. Time-to-solution and scalability are key parameters for codes to minimize turnaround times in order to scan e.g. tens of parameters such as the laser leading edge, resolve solid density target physics and run full-scale start-to-end simulations. PIConGPU reaches unprecedented performance by accelerating 100% of its computations on many-core architectures and leveraging next-generation scalable I/O. High-resolution, full-geometry studies on top-ten listed supercomputers decisively enhance predictive capabilities. PIConGPU's design allows for utilizing various compute architectures, including modern X86 and ARM CPUs and GPUs with a single, adaptable code base. Users can now run PIConGPU on almost any machine, either by easy recompiling or using predefined Docker images, and everybody can download, use and contribute to the code without extensive knowledge in compute architectures. We highlight latest additions to PIConGPU such as scalable file I/O via a new openPMD-API including ADIOS2 support for on the fly loosely coupled data analysis, live visualization with particle and field rendering, non-standard Gaussian laser pulses via Laguerre modes, in-situ X-ray scattering image generation, and an pythonic simulation setup interface.

Keywords: PIConGPU; Manycore; Scalable I/O; Alpaka; openPMD

  • Open Access Logo Lecture (Conference)
    4th European Advanced Accelerator Concepts Workshop (EAAC2019), 15.-20.09.2019, La Biodola Bay - 57037 Portoferraio Isola d’Elba, Repubblica Italiana

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29750


Origin of the butterfly magnetoresistance in a Dirac nodal-line system

Chiu, Y.-C.; Chen, K.-W.; Schönemann, R.; Quito, V. L.; Sur, S.; Zhou, Q.; Graf, D.; Kampert, W. A. G.; Förster, T.; Yang, K.; Mccandless, G. T.; Chan, J. Y.; Baumbach, R. E.; Johannes, M. D.; Balicas, L.

Abstract

We report a study on the magnetotransport properties and on the Fermi surfaces (FS) of ZrSi(Se,Te) semimetals. Density-functional theory (DFT) calculations, in absence of spin orbit coupling (SOC), reveal that both the Se and the Te compounds display Dirac nodal lines (DNL) close to the Fermi level εF at symmorphic and nonsymmorphic positions, respectively. We find that the geometry of their FSs agrees well with DFT predictions. ZrSiSe displays low residual resistivities, pronounced magnetoresistivity, high carrier mobilities, and a butterflylike angle-dependent magnetoresistivity (AMR), although its DNL is not protected against gap opening. As in Cd3As2, its transport lifetime is found to be 102 to 103 times larger than its quantum one. ZrSiTe, which possesses a protected DNL, displays conventional transport properties. Our evaluation indicates that both compounds most likely are topologically trivial. Nearly angle-independent effective masses with strong angle-dependent quantum lifetimes lead to the butterfly AMR in ZrSiSe.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-29749


The tremendous influence of hydrogenation on magnetism of NdMnGe

Ovchenkova, I. A.; Tereshina, I. S.; Bogdanov, A. E.; Tereshina-Chitrova, E. A.; Paukov, M. A.; Gorbunov, D.; Nikitin, S. A.

Abstract

The hydride NdMnGeH with the tetragonal ZrSiCuAs-type of structure (P4/nmm, N129, tP8) was obtained by hydrogen absorption at 523 K and 1 MPa from the NdMnGe intermetallic compound with a the tetragonal CeFeSi crystal structure (P4/nmm, N129, tP6). Measurements of magnetization in high magnetic fields up to 60 T and heat capacity measurements reveal pronounced changes in the magnetic properties of NdMnGe after hydrogenation. The Nd sublattice changes its ordering type from ferromagnetic to the antiferromagnetic one with a more than twofold decrease of and its magnetic ordering temperature (from 199 to 84 K). We explain the observed effects by the altered exchange interactions within the Nd sublattice resulting from the changed Nd–Nd interplane distances by interstitial atoms. The results are compared with data obtained previously for the NdMn1- xTixGe compounds, where the Ti substitution also changes significantly the magnetic properties.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-29748


Noble gases and radionuclides in Washington County iron meteorite

Ott, U.; Vogt, M.; Merchel, S.; Hopp, J.; Koll, D.; Lachner, J.; Trieloff, M.; Wallner, A.

Abstract

The Washington County iron meteorite is unique in that it contains solar-type noble gases (He and Ne). We report additional noble gas analyses, supplemented by radionuclide data obtained at ANU (Canberra) and VERA (Univ. Vienna). Activities in dpm/kg measured on two specimens taken close to those analyzed for noble gases are: 5.15/5.40 (¹⁰Be); 3.46/2.66 (²⁶Al); 23.7/22.2 (³⁶Cl); 425/448 (⁵³Mn). ⁶⁰Fe is 1.09/1.29 dpm/kg Ni. Both cosmogenic noble gases and radionuclides indicate a preatmospheric radius of at most 15 cm. The ³⁶Cl-³⁶Ar cosmic ray exposure age of ~120 Ma agrees well with that of [1] based on noble gases only and is in disagreement with the much longer age (575 Ma) obtained by [2] using the ⁴¹K/⁴⁰K method. The new noble gas data further confirm that the solar noble gases are volume-correlated, an inference being that the Earth’s iron core may constitute a potential source reservoir for the solar-type Ne observed in terrestrial mantle materials.
We thank S. Beutner for ICP-MS analyses.
[1] Vogt, M. (2018), PhD Diss., Univ. Heidelberg. [2] Voshage, H. (1967) Z. Naturforsch 22a, 477–506.

Keywords: meteorite; AMS

  • Lecture (Conference)
    Paneth Kolloquium, 29.-31.10.2019, Nördlingen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29747


The effect of long-range order on intermolecular interactions in organic semiconductors: zinc octaethyl porphyrin molecular thin film model systems.

Kumar, A.; Naumenko, D.; Rossi, G.; Magnano, E.; Nappini, S.; Bondino, F.; Segoloni, E.; Amidani, L.; D’Acapito, F.; Boscherini, F.; Barba, L.; Pace, E.; Benfatto, M.; Casassa, S.; Pedio, M.

Abstract

In order to optimize the performance of devices based on porphyrin thin films it is of great importance to gain a physical understanding of the various factors which affect their charge transport and lightharvesting properties. In this work, we have employed a multi-technique approach to study vacuum deposited zinc octaethyl porphyrin (ZnOEP) thin films with different degrees of long-range order as model systems. An asymmetrical stretching of the skeletal carbon atoms of the porphyrin conformer has been observed and attributed to ordered molecular stacking and intermolecular interactions. For ordered films, a detailed fitting analysis of the X-ray absorption near edge structure (XANES) using the MXAN code establishes a symmetry reduction in the molecular conformer involving the skeletal carbon atoms of the porphyrin ring; this highlights the consequences of increased p–p stacking of ZnOEP molecules adopting the triclinic structure. The observed asymmetrical stretching of the p conjugation network of the porphyrin structure can have significant implications for charge transport and light harvesting, significantly influencing the performance of porphyrin based devices.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29746


THz relaxation dynamics and nonlinear optics in graphene

Helm, M.

Abstract

Graphene, because of its peculiar linear band structure, shows some fascinating effects in the relaxation processes of excited electrons. Due to the zero band gap, many of those processes are best investigated at low energies, in the THz region. By linearly polarized pump-probe measurements we show that fast thermalization occurs only with respect to energy, but not to momentum, i.e. the electron distribution remains anisotropic for more than 5 ps (Phys. Rev. Lett. 117, 087401 (2016)). Applying a magnetic field splits the bands into non-equidistant Landau levels. This gives rise to a situation, where strong pumping of a Landau level actually leads to its depletion, due to strong Auger type electron-electron scattering (Nat. Phys. 11, 75 (2015)). In the same system, a large, resonant third-order optical nonlinearity is demonstrated via degenerate four-wave mixing (Nano Lett. 17, 2184 (2017)). All experiments were performed with a THz free-electron laser at frequencies around 20 THz, in collaboration with M. Mittendorff, J. König-Otto, S. Winnerl, A. Pashkin H. Schneider, with theory support by F. Wendler, T. Winzer, F. Kadi, E. Malic, A. Knorr, Y. Wang, A. Belyanin, and samples from W. de Heer and C. Berger.

Keywords: free electron laser; graphene; terahertz; relaxation; nonlinear optics

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    2D Materials 2019, 30.09.-04.10.2019, Sochi, Russia

Permalink: https://www.hzdr.de/publications/Publ-29745


Challenges for MR integrated Particle Therapy (MRiPT)

Lühr, A.

Abstract

The increasing interest for particle therapy (PT) builds on its unique depth-dose characteristics, which are exploited to achieve a significant reduction in normal-tissue dose deposition proximal and distal to the tumor volume. At the same time, this feature makes PT more susceptible to morphological variations (i.e. anatomical changes and organ motion) and patient set-up uncertainties than conventional high-energy X-ray therapy (XT).
The integration of magnetic resonance (MR) imaging and PT (MRiPT) at treatment isocenter would offer an opportunity to fully exploit the dosimetric benefit of PT and realize its true clinical potential, especially for moving tumors in the thorax and abdomen. The unparalleled soft-tissue contrast and real-time imaging capabilities provided by MR imaging allow for online tumor tracking and plan adaptation. Given the steep dose gradients of PT, its targeting accuracy is expected to benefit even more from MR-guidance than XT performed with hybrid MR-linear accelerator systems. Therefore, as a next step in the technological development of image-guided radiation therapy, the concept of integrating real-time MR image guidance with PT has gained significant interest in the scientific community over the past few years.
In this presentation, a number of technological challenges will be discussed that need to be overcome before patient treatment with MRiPT can safely be realized. These challenges include the following aspects: (a) distortion of the proton dose distribution by the magnetic fields of the MR scanner, (b) impact on the MR image quality by the static and dynamic electromagnetic fields of a PT facility, and (c) integration of the MR and PT systems for online adaptive treatment. Furthermore, the current status of a first functional proof-of-concept system for in-beam MR imaging at a PT research beam line installed at OncoRay in Dresden, Germany will be presented.

  • Invited lecture (Conferences)
    ESTRO meets Asia 2019, 06.-08.12.2019, Singapore, Singapore

Permalink: https://www.hzdr.de/publications/Publ-29744


Signatures of Technetium Oxidation States: A New Approach

Bauters, S.; Scheinost, A.; Schmeide, K.; Weiß, S.; Dardenne, K.; Rothe, J.; Mayordomo, N.; Steudtner, R.; Stumpf, T.; Abram, U.; Butorin, S.; Kvashnina, K.

Abstract

A general strategy for the determination of Tc oxidation state by new approach involving X-ray absorption near edge spectroscopy (XANES) at the Tc L₃ edge is shown. A comprehensive series of ⁹⁹Tc compounds, ranging from oxidation states I to VII, was measured and subsequently simulated within the framework of crystal-field multiplet theory. The observable trends in absorption edge energy shift in combination with the spectral shape allow for a deeper understanding of complicated Tc coordination chemistry. This approach can be extended to numerous studies of Tc systems as this method is one of the most sensitive methods for accurate Tc oxidation state and ligand characterization.

Keywords: Technetium L₃ edge XANES; Technetium oxidation states; Electronic structure; Crystal-field multiplet calculations

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29743


Basic verification of a numerical framework applied to a morphology adaptive multi-field two-fluid model considering bubble motions

Meller, R.; Schlegel, F.; Lucas, D.

Abstract

A morphology adaptive modeling framework is derived that is able to handle computationally efficiently dispersed as well as resolved interfacial structures coexisting in the computational domain with the same set of equations. The Eulerian multi-field two-fluid model is combined with the compact momentum interpolation method for multiple phases, which has been proposed in the literature as an extension to the Rhie-Chow pressure-velocity coupling. Additionally to the interfacial drag force, the virtual mass force is consistently accounted for in the model. Utilizing a specialized interfacial drag formulation, large interfacial structures can be described with the presented method in a volume-of-fluid-like manner, additionally to the disperse description. The strong phase coupling due to the drag closure model in interfacial regions is resolved with a partial elimination algorithm, which is adapted to work in an approximate manner for more than two phases via a sum formulation. The presented model is implemented in the C++ library OpenFOAM and solver performance is compared to results obtained with the homogeneous model approach in two cases of a single rising gas bubble for two- and three-dimensional space, respectively. Additionally, for both three-dimensional cases, the results are compared to experimental data. Finally, the presented method’s capability of representing dispersed and resolved interfacial structures at the same time is demonstrated with two test cases: a two-dimensional gas bubble, rising in a liquid, which is laden with micro gas bubbles, and a two-dimensional stagnant stratification of water and oil, sharing a large-scale interface, which is penetrated by micro gas bubbles.

Keywords: Finite volume method; Multiphase flow; Multi-field two-fluid model; Eulerian-Eulerian model; Momentum interpolation; Partial elimination algorithm

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29742


Infrared nanospectroscopy at cryogenic temperatures and on semiconductor nanowires

Lang, D.

Abstract

This PhD thesis concentrates on scattering scanning near-field infrared microscopy (s-SNIM) which utilizes the radiation from the free-electron laser (FEL) at the Helmholtz-Zentrum Dresden-Rossendorf. The FEL is an intense, narrow-band radiation source, tunable from the mid- to far-infrared spectral range (5 meV to 250 meV). The s-SNIM technique enables infrared microscopy and spectroscopy with a wavelength-independent spatial resolution of about 10nm. The first part demonstrates the extension of s-SNIM at the FEL towards cryogenic temperatures as low as 5K. To this end, we show the functionality of our low-temperature s-SNIM apparatus on different samples such as Au, structured Si/SiO2, as well as the multiferroic material gallium vanadium sulfide (GaV4S8). The latter material recently attracted a lot of interest since it hosts a Néel-type skyrmion lattice – a periodic array of spin vortices. Below T = 42K, GaV4S8 undergoes a structural phase transition and then forms ferroelectric domains, which we can map out by low-tempererature s-SNIM. Notably, we found a strong impact on the ferroelectric domains upon infrared irradiation, which we further utilize to calibrate the local heat contribution of the focused infrared beam beneath the s-SNIM probe.
The second part of this thesis contains comprehensive s-SNIM investigations of high-quality semiconductor nanowires (NWs) rown by molecular beam epitaxy. Such NWs are promising building blocks for fast (opto-)electronic nanodevices, amongst thers due to their high carrier mobility. We have examined highly doped GaAs/InGaAs core/shell NWs and observed a strong and spectrally sharp plasmonic resonance at about hw = 125 meV, using a continuous wave CO2 laser for probing. If we probe the same NWs utilizing the intense, pulsed FEL radiation, we observe a pronounced redshift to hw < 100 meV and a broading of the plasmonic response. This nonlinear response is most likely induced by heating of the electron gas upon irradiation by the strong FEL pulses. Our observations open up the possibility to actively induce and observe non-equilibrium states in s-SNIM directly by the mid-infrared beam. Beside the nonlinear effect, we prepared and measured cross sections of both homogeneously-doped and modulation-doped core/shell NWs.

Involved research facilities

Related publications

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-105 2019
    ISSN: 2191-8708, eISSN: 2191-8716

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29741


A study on the relationship between upstream and downstream conditions in swirling two-phase flow

Sahovic, B.; Atmani, H.; Wiedemann, P.; Schleicher, E.; Legendre, D.; Climent, E.; Zamanski, R.; Pedrono, A.; Hampel, U.

Abstract

Inline fluid separation is a concept, which is used in the oil and gas industry. Inline fluid separators typically have a static design and hence changing inlet conditions lead to less efficient phase separation. For introducing flow control into such a device, additional information is needed about the relationship of upstream and downstream conditions. This paper introduces a study on this relationship for gas/liquid two-phase flow. The downstream gas core development was analyzed for horizontal device installation in dependence of the inlet gas and liquid flow rates. A wire-mesh sensor was used for determining two-phase flow parameters upstream and a high-speed video camera to obtain core parameters downstream the swirling device. For higher accuracy of the calculated void fraction, a novel method for wire-mesh sensor data analysis has been implemented. Experimental results have shown that void fraction data of the wire-mesh sensor can be used to predict the downstream behavior for a majority of the investigated cases. Additionally, the upstream flow pattern has an impact on the stability of the gas core downstream which was determined by means of experimental data analysis.

Keywords: Gas-liquid flow; inline fluid separation; swirling element; wire-mesh sensor; digital image processing; high-speed camera

Permalink: https://www.hzdr.de/publications/Publ-29740


Reducible contributions to quantum electrodynamics in external fields

Ahmadiniaz, N.; Edwards, J. P.; Ilderton, A.

Abstract

We consider one-particle reducible (1PR) contributions to QED and scalar QED processes in external fields, at one-loop and two-loop order. We investigate three cases in detail: constant crossed fields, constant magnetic fields, and plane waves. We find that 1PR tadpole contributions in plane waves and constant crossed fields are non-zero, but contribute only divergences to be renormalised away. In constant magnetic fields, on the other hand, tadpole contributions give physical corrections to processes at one-loop and beyond. Our calculations are exact in the external fields and we give strong and weak field expansions in the magnetic case.

Permalink: https://www.hzdr.de/publications/Publ-29739


Compton-like scattering of a scalar particle with N photons and one graviton

Ahmadiniaz, N.; Balli, F. M.; Corradini, O.; Dávila, J. M.; Schubert, C.

Abstract

Tree-level scattering amplitudes for a scalar particle coupled to an arbitrary number N of photons and a single graviton are computed. We employ the worldline formalism as the main tool to compute the irreducible part of the amplitude, where all the photons and the graviton are directly attached to the scalar line, then derive a tree replacement rule to construct the reducible parts of the amplitude which involve irreducible pure N-photon two-scalar amplitudes where one photon line emits the graviton. We test our construction by verifying the on-shell gauge and diffeomorphism Ward identities, at arbitrary N.

Keywords: Scattering amplitudes; gravitons; Ward identities

Permalink: https://www.hzdr.de/publications/Publ-29738


Compliant magnetic field sensors for flexible electronics

Makarov, D.

Abstract

I will review our recent activities on compliant magnetic field sensors.

Keywords: flexible electronics; shapeable magnetoelectronis

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    FFlexCom Meeting 2019; DFG Priority Programme “High Frequency Flexible Bendable Electronics for Wireless Communication Systems”, SPP 1796, 07.10.2019, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-29737


Helium interactions with (Y, Ti, O) nanoclusters in bcc Fe

Vallinayagam, M.; Posselt, M.; Faßbender, J.

Abstract

Nanometer size (Y, Ti, O) clusters in nanostructured ferritic/martensitic Fe-Cr alloys can act as sinks for the transmutation product helium. In this manner irradiation swelling can be retarded significantly. Many details of He storage in or near the clusters are still not understood. In this work interactions of He with (Y, Ti, O) clusters in bcc Fe are investigated by density functional theory (DFT) calculations. Four different cluster structures studied in our previous work [1] are considered: Cage-type clusters with (i) 6 O atoms, 9 vacancies (v) and 6 Y atoms, and (ii) with 7 O, 9 v, 3 Y, and 3 Ti, as well as clusters with O in the center containing (iii) 6 O, 9 v, 6 Y, and (iv) 7 O, 9 v, 3 Y, 3 Ti. It is found that the most stable position of He is in the center of the cluster, followed by the interfacial substitutional site and other interstitial positions between metal or oxygen atoms, and sites away from the cluster. This shows the He trapping may be nearly irrespective of cluster morphology and mainly depend on cluster composition. Adding a second He atom to the cluster structure is investigated for selected cases. Furthermore, barriers for possible jumps between different sites at the rim of the cluster and the center are determined. First results show that these barriers are higher if the cluster contains Ti and that there is a strong dependence on the particular position at the rim. For the discussion of the results also the DFT data obtained from studies on the interaction of He with single O, Y, and Ti atoms as well as with a single vacancy are used.

[1] Vallinayagam et.al. Investigation of structural models for O-Y and O-Y-Ti clusters in bcc Fe: A DFT study J. Phys.: Condens. Matter (2018) https://doi.org/10.1088/1361-648X/aaf9cd

Keywords: DFT; ODS; He storage

  • Lecture (Conference)
    EUROMAT-2019 Conference, 01.-05.09.2019, Stockholm, Sweden

Permalink: https://www.hzdr.de/publications/Publ-29736


Validating the Predictive Power of Statistical Models in Retrieving Leaf Dry Matter Content of a Coastal Wetland from a Sentinel-2 Image

Ali, A. M.; Darvishzadeh, R.; Rafiezadeh Shahi, K.; Skidmore, A.

Abstract

Leaf dry matter content (LDMC), the ratio of leaf dry mass to its fresh mass, is a key plant trait, which is an indicator for many critical aspects of plant growth and survival. Accurate and fast detection of the spatiotemporal dynamics of LDMC would help understanding plants' carbon assimilation and relative growth rate, and may then be used as an input for vegetation process models to monitor ecosystems. Satellite remote sensing is an effective tool for predicting such plant traits non-destructively. However, studies on the applicability of remote sensing for LDMC retrieval are scarce. Only a few studies have looked into the practicality of using remotely sensed data for the prediction of LDMC in a forest ecosystem. In this study, we assessed the performance of partial least squares regression (PLSR) plus 11 widely used vegetation indices (VIs), calculated based on different combinations of Sentinel-2 bands, in predicting LDMC in a coastal wetland. The accuracy of the selected methods was validated using LDMC, destructively measured in 50 randomly distributed sample plots at the study site in Schiermonnikoog, the Netherlands. The PLSR applied to canopy reflectance of Sentinel-2 bands resulted in accurate prediction of LDMC (coefficient of determination (R-2) = 0.71, RMSE = 0.033). PLSR applied to the studied VIs provided an R-2 of 0.70 and RMSE of 0.033. Four vegetation indices (enhanced vegetation index(EVI), specific leaf area vegetation index (SLAVI), simple ratio vegetation index (SRVI), and visible atmospherically resistant index (VARI)) computed using band 3 (green) and band 11 of the Sentinel-2 performed equally well and achieved a good measure of accuracy (R-2 = 0.67, RMSE = 0.034). Our findings demonstrate the feasibility of using Sentinel-2 surface reflectance data to map LDMC in a coastal wetland.

Keywords: LDMC; PLSR; vegetation indices; Sentinel-2; wetland

Permalink: https://www.hzdr.de/publications/Publ-29735


First principles calculations of the thermodynamic stability of Ba, Zr, and O vacancies in BaZrO3

Nadarajan, R.; Devaraj, M.; Satyanarayana, S. V. M.; Posselt, M.

Abstract

The temperature dependence of the stability of bulk BaZrO3 (BZO) and of the vacancies in this material is investigated by considering phonon contributions to the free energy. The stability diagram of BZO is determined for different chemical environments. With increasing temperature the stability region becomes smaller which is particularly caused by the strong temperature dependence of the chemical potential of gaseous oxygen. The free formation energy of Ba, Zr, and O vacancies in BZO is calculated for all possible charge states and for different atomic reservoirs. While the free formation energy of Zr vacancies is strongly influenced by temperature a weaker dependence is found for Ba and O vacancies. This has also an effect on the charge transition levels at different temperatures. Present results demonstrate that O poor reservoir conditions and a Fermi level close to the valence band maximum favour a high concentration of doubly positively charged O vacancies which is a prerequisite to get a large number of protonic defects and a good proton conductivity. In such a chemical environment the amount of Ba and Zr vacancies is low so that Ba and Zr deficiencies are not an important issue and BZO stays sufficiently stable.

Keywords: DFT; Barium Zirconate; thermodynamic stability; vacancies

Permalink: https://www.hzdr.de/publications/Publ-29734


Comparison of Eulerian QBMM and classical Eulerian – Eulerian method for the simulation of polydisperse bubbly flows

Li, D.; Marchisio, D.; Hasse, C.; Lucas, D.

Abstract

The spatial gas distribution of poly-disperse bubbly flows depends greatly on the bubble size. To reflect the resulting polycelerity, more than two momentum balance equations (typically for the gas and liquid phases) have to be considered, as done in the multifluid approach. The inhomogeneous multiple-size group model follows this approach, also combined with a population balance model. As an alternative, in a previous work, an Eulerian quadrature-based moments method (E-QBMM) was implemented in OpenFOAM; however, only the drag force was included. In this work, different nondrag forces (lift, wall lubrication, and turbulent dispersion) are added to enable more complex test cases to be simulated. Simulation results obtained using E-QBMM are compared with the classical E – E method and validated against experimental data for different test cases. The results show that there is good agreement between E-QBMM and E – E methods for mono-disperse cases, but E-QBMM can better simulate the separation and segregation of small and large bubbles.

Keywords: bubbly flow; E – E method; E-QBMM; non-drag forces; wall peak

Permalink: https://www.hzdr.de/publications/Publ-29733


Radio- and photosensitization of plasmid DNA by DNA binding ligand propidium iodide: Investigation of Auger electron induction and detection of Cherenkov-emission

Kotzerke, J.; Runge, R.; Gotze, P.; Wunderlich, G.; Enghardt, W.; Freudenberg, R.

Abstract

Purpose We investigated whether propidium iodide (PI) enhances DNA damaging effects of ionizing and non-ionizing radiation species (X-rays, alpha-, beta-, auger electron emission and light of various wavelengths, respectively). This biophysical experimental setting allowed us, furthermore, to investigate whether Cherenkov emission can be detected by photodynamic effects and increased DNA damage.
Material and methods Conformation changes of plasmid DNA were detected and quantified by gelelectrophoresis and fluorescence imaging. Hydrogen peroxide, stannous dichloride, and dimethylsulfoxide were used as chemical modulators, Tc-99m, Re-188, Ra-223, and x-ray (32 kV and 200 kV) reflected radiotoxicity and light (lambda = 254 nm, 366 nm and 530-575 nm) induced phototoxicity.
Results Radiotracers and x-rays induced dose dependent DNA damage. PI did not serve as radiosensitizer in radioisotopes, while a low effect was detected in X-rays. The phototoxicity was dependent on the wavelengths of light. Light with a wavelength range of 530-575 nm in combination with PI resulted in direct DNA damage. The yield of Cherenkov emission was far below the photon emission of light irradiation and not distinguishable from general radiotoxicity.
Conclusions PI binds to plasmid DNA, is not chemotoxic, and increases radiotoxicity only to minor extent. Phototoxicity and its stimulation by PI is dependent on the wavelength of the light. No kind of energy deposition was capable of inducing an Auger electron cascade.
Furthermore, no increase in DNA damage induced by photodynamic effects from Cherenkov emission was detectable.

Keywords: Probidium Iodide; Plasmid DNA; Auger Electrons; Cherenkov Emission

Permalink: https://www.hzdr.de/publications/Publ-29732


Radioresistance of KRAS/TP53-mutated lung cancer can be overcome by radiation dose escalation or EGFR tyrosine kinase inhibition in vivo

Gurtner, K.; Kryzmien, Z.; Koi, L.; Wang, M.; Benes, C.; Hering, S.; Willers, H.; Baumann, M.; Krause, M.

Abstract

Recent clinical data have linked KRAS/TP53 comutation (mut) to resistance to radiotherapy (RT), but supporting laboratory in vivo evidence is lacking. In addition, the ability of different radiation doses, with/without epidermal growth factor receptor (EGFR)-directed treatment, to achieve local tumor control as a function of KRAS status is unknown. Here, we assessed clonogenic radiation survival of a panel of annotated lung cancer cell lines. KRASmut/TP53mut was associated with the highest radioresistance in nonisogenic and isogenic comparisons. To validate these findings, isogenic TP53mut NCI-H1703 models, KRASmut or wild-type (wt), were grown as heterotopic xenografts in nude mice. A clinical RT schedule of 30 fractions over 6 weeks was employed. The dose that controlled 50% of tumors (TCD50) was calculated. The TCD50 for KRASwt/TP53mut xenografts was 43.1 Gy whereas KRASmut/TP53mut tumors required a 1.9-fold higher TCD50 of 81.4 Gy. The EGFR inhibitor erlotinib radiosensitized KRASmut but not KRASwt cells and xenografts.
The TCD50 associated with adding erlotinib to RT was 58.8 Gy for KRASmut, that is, a 1.4-fold dose enhancement. However, the EGFR antibody cetuximab did not have a radiosensitizing effect. In conclusion, we demonstrate for the first time that KRASmut in a TP53mut background confers radioresistance when studying a clinical RT schedule and local control rather than tumor growth delay. Despite the known unresponsiveness of KRASmut tumors to EGFR inhibitors, erlotinib radiosensitized KRASmut tumors. Our data highlight KRAS/TP53 comutation as a candidate biomarker of radioresistance that can be at least partially reversed by dose escalation or the addition of a targeted agent.

Permalink: https://www.hzdr.de/publications/Publ-29731


Comparable radiation response of ex vivo and in vivo irradiated tumor samples determined by residual γH2AX

Rassamegevanon, T.; Löck, S.; Baumann, M.; Krause, M.; von Neubeck, C.

Abstract

Purpose: a) To investigate if an ex vivo cultured and irradiated tumor biopsy reflects and predicts the radiation response of the corresponding in vivo irradiated tumor measured with the DNA double strand break marker γH2AX foci. Materials and methods: Five human head and neck squamous cell carcinoma (hHNSCC) xenograft models were used. Fine needle biopsies were taken from anesthetized tumor-bearing NMRI nude mice prior to in vivo single dose irradiation (0, 2, 4, or 8 Gy) under ambient blood flow. Biopsies were ex vivo reoxygenated and irradiated with equivalent doses. Tumors and biopsies were fixed 24 h post irradiation, and γH2AX foci were assessed in oxygenated tumor regions. Results: Linear regression analysis showed comparable slopes of the residual γH2AX foci dose–response curves in four out of five hHNSCC models when in vivo and ex vivo cohorts were compared. The slopes from ex vivo biopsies and in vivo tumors could classify the respective tumor model as sensitive or resistant according to the intrinsic radiation sensitivity (TCD50). Conclusion: The ability of ex vivo irradiated tumor biopsies to reflect and predict the intrinsic radiation response of in vivo tumors increases the translational potential of the ex vivo γH2AX foci assay as a diagnostic tool for clinical practice. © 2019 Elsevier B.V.

Keywords: Intrinsic radiation sensitivity; Predictive biomarker; Radiation therapy; γH2AX foci

Downloads

Permalink: https://www.hzdr.de/publications/Publ-29730


Lift Forces on Solid Spherical Particles in Wall-bounded Flows

Shi, P.; Rzehak, R.

Abstract

The present work is concerned with the lift forces acting on particles immersed in a wall-bounded fluid. Conditions where the particle translates in a fluid at rest and in a linear shear flow are considered. Likewise, non-rotating particles and particles in free rotation driven solely by the flow are considered. Furthermore, situations where the wall lies in the inner region and in the outer region of the flow disturbance produced by the particle are distinguished. The focus is on solid spherical particles at Reynolds numbers up to O(〖10〗^2 ) which are relevant for particulate flows in chemical and minerals engineering. A comprehensive review of existing results from analytical, experimental, and direct numerical simulation studies is given. The available correlations are critically assessed by comparison to data from these studies. Based on the comparison recommendations are given which correlations to use, including some new proposals, and gaps in the data are identified.

Keywords: lift force; particles; wall-bounded flow; particle rotation; inner / outer region; correlation

Permalink: https://www.hzdr.de/publications/Publ-29729


Au incorporation into various ZnO crystallographic cuts realised by ion implantation – ZnO damage characterization

Mackova, A.; Malinsky, P.; Jagerova, A.; Miksova, R.; Nekvindova, P.; Cajzl, J.; Böttger, R.; Akhmadaliev, S.

Abstract

Non-polar surfaces, such as a-plane (11–20) and m-plane (10-10), for ZnO have become more attractive as numerous efforts have recently been made to grow non-polar ZnO facets for applications in nanoscale photonic devices. Noble-metal incorporation into transparent semiconductors such as ZnO has been investigated because of the non-linear optical response of such structures. This paper presents a study of defect evolution in various ZnO crystallographic cuts caused by Au implantation. The investigation has focused on ZnO structure characterisation, Au distribution and the interior morphology of the a-, m- and c-planes ZnO single crystals implanted with 400 keV Au+ ions at the ion fluences of 5 × 1014 and 1 × 1015 cm−2 and subsequently annealed at 600 °C in O2. The structure modification was studied using Rutherford backscattering spectrometry (RBS) in the channelling mode (RBS/C) and Raman spectroscopy. After the ion-implantation process, low surface damage was observed in all ZnO orientations unlike deep structural damage. Deep structural damage grew with increased Au-ion fluence and Au did not exhibit strong out-diffusion from the depth to the surface during the post-implantation annealing. Small but noticeable differences were observed between different ZnO orientations. RBS measurements during ion implantation revealed more progressive deep-damage formation in the c- and m-planes than in the a-plane ZnO. Simultaneously, the smallest Zn sub-lattice disorder deduced from RBS/C measurements was observed in the a-plane ZnO. During post-implantation annealing, a slight structure recovery (about 4%) was observed in all orientations. Raman spectroscopy confirmed the increasing structure disorder with the enhanced ion fluence for all as-implanted ZnO orientations and a partial reconstruction of the ZnO structure during annealing, when the intensity of E2 phonons was increased and that of longitudinal optical (LO) phonons was suppressed because of the disorder recovery. E2 (high) and E1(LO) Raman phonon modes connected with oxygen sub-lattice ordering/disordering have been investigated in detail – they show a significant modification mainly in the m-plane. The cause of the different behaviour of ZnO planes as well as the differences in the incorporation and movement of Au and Er atoms in the ZnO structure are discussed in the work.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-29728


Entwicklung des Gesamtsystems - Stand der Modellierungs- und Simulationsarbeiten

Fogel, S.

Abstract

Entwicklung eines tubularen Dampf-Elektrolyseurs mit integrierter Kohlenwasserstoffsynthese (DELTA)

Involved research facilities

  • TOPFLOW Facility
  • Lecture (others)
    5. Projekttreffen DELTA, 25.04.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29727


Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.] [350.] [351.] [352.]