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35836 Publications

MR-guided proton therapy: a review and a preview

Hoffmann, A.; Oborn, B.; Moteabbed, M.; Yan, S.; Bortfeld, T.; Knopf, A.; Fuchs, H.; Georg, D.; Seco, J.; Francesca Spadea, M.; Jäkel, O.; Kurz, C.; Parodi, K.

Background
The targeting accuracy of proton therapy (PT) for moving soft-tissue tumours is expected to greatly improve by real-time magnetic resonance imaging (MRI) guidance. The integration of MRI and PT at the treatment isocenter would offer the opportunity of combining the unparalleled soft-tissue contrast and real-time imaging capabilities of MRI with the most conformal dose distribution and best dose steering capability provided by modern PT. However, hybrid systems for MR-integrated PT (MRiPT) have not been realized so far due to a number of hitherto open technological challenges. In recent years, various research groups have started addressing these challenges and exploring the technical feasibility and clinical potential of MRiPT. The aim of this contribution is to review the different aspects of MRiPT, to report on the status quo and to identify important future research topics.

Methods
Four aspects currently under study and their future directions are discussed: modelling and experimental investigations of electromagnetic interactions between the MRI and PT systems, integration of MRiPT workflows in clinical facilities, proton dose calculation algorithms in magnetic fields, and MRI-only based proton treatment planning approaches.

Conclusions
Although MRiPT is still in its infancy, significant progress on all four aspects has been made, showing promising results that justify further efforts for research and development to be undertaken. First non-clinical research solutions have recently been realized and are being thoroughly characterized. The prospect that first prototype MRiPT systems for clinical use will likely exist within the next 5 to 10 years seems realistic, but requires significant work to be performed by collaborative efforts of research groups and industrial partners.

Keywords: Proton therapy; magnetic resonance imaging; image guidance

Permalink: https://www.hzdr.de/publications/Publ-31038
Publ.-Id: 31038


Clinical outcome of PSMA-guided radiotherapy for patients with oligorecurrent prostate cancer

Koerber, S. A.; Sprute, K.; Kratochwil, C.; Winter, E.; Haefner, M. F.; Katayama, S.; Schlampp, I.; Herfarth, K.; Kopka, K.; Afshar-Oromieh, A.; Zschaebitz, S.; Holland-Letz, T.; Choyke, P. L.; Jaeger, D.; Hohenfellner, M.; Haberkorn, U.; Debus, J.; Giesel, F. L.

Purpose.
First-line treatment of patients with recurrent, metastatic prostate cancer involves hormone therapy with or without additional systemic therapies. Prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) allows the detection of oligometastatic disease that may be amenable to image-guided radiotherapy. The current study classifies the type and localization of metastases and the clinical outcome of PSMA-PET/CT-guided radiotherapy to selected metastases.
Materials and methods.
Between 2011 and 2019, 86 patients with recurrent, oligometastatic prostate carcinoma were identified by PSMA-PET/CT and were treated with image-guided radiotherapy of their metastases. Sites of relapse were characterized, and the primary endpoint overall survival (OS), biochemical progression-free survival (bPFS), and androgen deprivation therapy (ADT)-free survival were tabulated.
Results
In total, 37% of the metastases were bone metastases, 48% were pelvic nodalmetastases, and 15% were nodalmetastases outside of the pelvis. After PSMA-guided radiotherapy, a biochemical response was detected in 83% of the cohort. A statistically significant decrease in the standard uptake value (SUV) was seen in irradiated metastases. After a median follow-up of 26 months, the 3-year OS and bPFS were 84% and 55%, respectively. The median time of ADT-free survival was 13.5 months. A better clinical outcome was observed for patients receiving concomitant ADT or more than 24 fractions of radiation.
Conclusion.
PSMA-guided radiotherapy is a promising therapeutic approach with excellent infield control for men with oligorecurrent prostate carcinoma. However, prospective, randomized trials are necessary to determine if this approach confers a survival advantage.

Keywords: Prostate cancer; PSMA; PET; Metastases; SUV; OS

Permalink: https://www.hzdr.de/publications/Publ-31037
Publ.-Id: 31037


Oscillatory surface deformation of paramagnetic rare earth solutions driven by an inhomogeneous magnetic field

Fritzsche, B.; Mutschke, G.; Meinel, T.; Yang, X.; Lei, Z.; Eckert, K.

The deformation of the free surface of a paramagnetic liquid subjected to a non-uniform magnetic field has been studied. A transient deformation of the surface caused by the interplay of gravity, magnetic field and surface tension is observed when a permanent magnet is moved vertically downwards to the free surface of the liquid. Different concentrations of rare-earth metal salt (DyCl 3 ) were used and different magnet velocities were studied. The deformation of the interface was followed optically by means of a microscope and recorded with a high-speed camera. The experimental results are compared and discussed with complementary numerical simulations. Detailed results are given for the static shape of the deformed surface and the temporal evolution of the surface deformation below the center of the magnet. The frequency of the surface oscillations is found to depend on the concentration of the salt and is compared with analytical findings. Finally, a potential application of the effects observed is presented.

Keywords: Magnetic field; magnetic gradient force; rare earth; dysprosium; interfacial instability; free surface; oscillations

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Permalink: https://www.hzdr.de/publications/Publ-31036
Publ.-Id: 31036


Characterization of magnetic interference and image artefacts during simultaneous in-beam MR imaging and proton pencil beam scanning

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

For the first time, a low-field open magnetic resonance (MR) scanner was combined with a proton pencil beam scanning (PBS) research beamline. The aim of this study was to characterize the magnetic fringe fields produced by the PBS system and measure their effects on MR image quality during simultaneous PBS irradiation and image acquisition. A magnetic field camera measured the change in central resonance frequency (Δfres) and magnetic field homogeneity (ΔMFH) of the B0 field of the MR scanner during operation of the beam transport and scanning magnets. The beam energy was varied between 70−220 MeV and beam scanning was performed along the central horizontal and vertical axis of a 48 × 24 cm2 radiation field. The time structure of the scanning magnets’ fringe fields was simultaneously recorded by a tri-axial Hall probe. MR imaging experiments were conducted using the ACR (American College of Radiology) Small MRI Phantom and a spoiled gradient echo pulse sequence during simultaneous volumetric irradiation. Computer simulations were performed to predict the effects of B0 field perturbations due to PBS irradiation on MR image formation in k-space. Setting the beam transport magnets, horizontal and vertical scanning magnets resulted in a maximum Δfres of 50, 235 and 4 Hz, respectively. The ΔMFH was less than 3 ppm for all measurements. MR images acquired during beam energy variation and vertical beam scanning showed no visual loss in image quality. However, MR images acquired during horizontal beam scanning showed severe coherent ghosting artefacts in phase encoding direction. Both simulated and measured k-space phase maps prove that these artefacts are caused by phase-offsets. This study shows first experimental evidence that simultaneous in-beam MR imaging during proton PBS irradiation is subject to severe loss of image quality in the absence of magnetic decoupling between the PBS and MR system.

Keywords: MRI; proton therapy; image quality; pencil beam scanning; magnetometry

Permalink: https://www.hzdr.de/publications/Publ-31035
Publ.-Id: 31035


Broadband Infrared LEDs based on Europium-To-Terbium Charge Transfer Luminescence

Joos, J.; van der Heggen, D.; Martin, L.; Amidani, L.; Smet, P.; Barandiarán, Z.; Seijo, L.

A broadband infrared (IR) light-emitting diode (LED) for versatile spectroscopic use is constructed, based on a novel type of broadband IR luminescence. This peculiar emission is identified in europium and terbium codoped CaS for which the spectrum partially overlaps with the red Eu2+ emission and ranges up to 1200 nm. It can be efficiently excited with visible light. Experimental evidence for metal-to-metal charge transfer (MMCT) luminescence is collected, comprising data from luminescence spectroscopy, microscopy and X-ray spectroscopy. State-of-the-art multiconfigurational ab initio calculations allow to attribute the infrared band to the radiative decay of a metastable MMCT state of a Eu2+-Tb3+ pair. The calculations explain why no MMCT emission is found in the similar compound SrS:Eu,Tb and are used to anticipate how to fine-tune the characteristics of the MMCT luminescence.

Permalink: https://www.hzdr.de/publications/Publ-31034
Publ.-Id: 31034


Determination of thermodynamic functions and structural parameters of NpO2+ lactate complexes

Maiwald, M. M.; Müller, K.; Heim, K.; Trumm, M.; Fröhlich, D. R.; Banik, N. L.; Rothe, J.; Dardenne, K.; Skerencak-Frech, A.; Panak, P. J.

The complexation of NpO2+ with lactate in aqueous solution is studied as a function of the total ligand concentration ([Lac-]total), ionic strength (Im = 0.5 – 4.0 mol kg-1 Na+(Cl-/ClO4-)) and temperature (T = 20 – 85 °C) by Vis/NIR absorption spectroscopy. The formation of two NpO2+ lactate species with the stoichiometry NpO2(Lac)n1-n (n = 1, 2) is observed at the studied experimental conditions. The temperature dependent conditional stability constants log beta 'j(T) at different ionic strengths are calculated with the law of mass action. The conditional data are extrapolated to IUPAC reference state conditions (Im = 0) with the specific ion interaction theory (SIT). With increasing temperature up to 85 °C log beta 01(20 °C) = 1.92 ± 0.14 decreases by 0.12 and log beta 02(20 °C) = 2.10 ± 0.13 decreases by 0.17. The thermodynamic stability constants correlate linearly with the reciprocal temperature according to the integrated Van’t Hoff equation. Thus, linear regression analyses yield the standard reaction enthalpy delta rH0 and entropy delta rS0 for the complexation reactions. In addition, the sum of the SIT specific binary ion-ion interaction coefficients delta epsilon j,k(T) of the complexation reactions are determined by variation of the ionic strength.
Structural parameters of the formed complex species and the coordination mode of lactate towards the NpO2+ ion are investigated as a function of pHc by extended x-ray absorption fine structure spectroscopy (EXAFS) and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FT IR). The results show, that the coordination mode of lactate changes from end-on (coordination via only the COO- group) to side-on (formation of chelate rings involving the OH-group) with increasing pHc. The experiments are supported by quantum chemical calculations.

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Permalink: https://www.hzdr.de/publications/Publ-31033
Publ.-Id: 31033


The role of postoperative thoracic radiotherapy and prophylactic cranial irradiation in early stage small cell lung cancer: patient selection among ESTRO experts

Putora, P.; de Ruysscher, D.; Glatzer, M.; Widder, J.; van Houtte, P.; Troost, E. G. C.; Slotman, B.; Ramella, S.; Pöttgen, C.; Peeters, S.; Nestle, U.; Mcdonald, F.; Le, P. C.; Dziadziuszko, R.; Belderbos, J.; Faivre-Finn, C.

The role of prophylactic cranial irradiation (PCI) and thoracic radiotherapy (TRT) is unclear in resected small cell lung cancer (SCLC). Methods: Thirteen European radiotherapy experts on SCLC were asked to describe their strategies on PCI and TRT for patients with resected SCLC. The treatment strategies were converted into decision trees and analyzed for consensus and discrepancies. Results: For patients with resected SCLC and positive lymph nodes most experts recommend prophylactic cranial irradiation and thoracic radiotherapy. For elderly patients with resected node negative SCLC, most experts do not recommend thoracic radiotherapy or prophylactic cranial irradiation. Conclusion: PCI and TRT are considered in patients with resected SCLC and these treatments should be discussed with the patient in the context of shared decision-making.

Permalink: https://www.hzdr.de/publications/Publ-31032
Publ.-Id: 31032


Is reducing irradiated margins key to improving outcomes for radiotherapy

van Herk, M.; Osorio, E.; Troost, E. G. C.

Radiotherapy is a four-dimensional geometrical challenge. For modern radiotherapy planning, gross tumour volume (GTV) is pictured before treatment using CT scanning fused with anatomical and functional imaging. To account for microscopic tumour spread, a safety margin is added to the GTV and corrected for anatomical boundaries to determine the clinical target volume (CTV). Finally, systematic and random errors occurring during the fractionated course of radiotherapy are corrected for by adding another safety margin.

  • Lancet Oncology 20(2019)9, 1208-1210

Permalink: https://www.hzdr.de/publications/Publ-31031
Publ.-Id: 31031


Integral multi-scenario robustness evaluation of classical and anatomical robust optimization in head and neck cancer proton therapy

Cubillos Mesias, M.; Troost, E. G. C.; Lohaus, F.; Agolli, L.; Rehm, M.; Richter, C.; Stützer, K.

Classical robust optimization considers uncertainties in patient setup and particle range. Usually plan robustness is evaluated from calculation of perturbed dose distributions based on the planning CT, without considering potential anatomical changes that may occur during the treatment course. Our aim was to compare the overall plan robustness of classical robust optimization (cRO) with the recently proposed anatomical robust optimization (aRO) based on an integral multi-scenario evaluation, considering all types of uncertainties including anatomical variations.

  • Abstract in refereed journal
    Radiotherapy and Oncology 133(2019)1, S488-S489

Permalink: https://www.hzdr.de/publications/Publ-31030
Publ.-Id: 31030


Combined Two-phase Co-flow and Counter-flow in a Gas Channel/Porous Transport Layer Assembly

Beale, S. B.; Andersson, M.; Weber, N.; Marschall, H.; Lehnert, W.

Polymer electrolyte fuel cells and electrolysers are low temperature devices whereby both gases and liquids intermingle within the porous transport layers and open channels. The flow of the liquid and gas is of paramount importance to the functioning of the unit. This motion is poorly understood. Cell-level models typically employ volume-averaging techniques to describe the motion of the flowing reactants and products. Until recently, detailed analysis of the two-phase liquid gas mixture, employing front-tracking methods has proved to be computationally prohibitive. Previous work has considered the motion of liquid drops in gas channels, it being assumed the drops are formed at specific nucleation sites on the sides of the channels. The present work considers a detailed numerical analysis of combined liquid-gas co-flow in a gas channel with liquid-gas counter-flow in a porous transport layer, (PTL). The geometry considered is in the form of a ‘T-shape’ with the porous transport layer of a thin rectangular prism of dimensions 0.5×0.5×0.1 mm3 located at the base of the ‘T’, and the gas flowing across the top in channel. The PTL is reproduced by digital reconstruction of nano-computer tomography images of a Freudenberg H2315 PTL as a sterolithography file. From this, the domain is tessellated with an unstructured castellated, or octree, type mesh. Liquid water is introduced at an electrode at the base of the PTL and gaseous oxygen is simultaneously removed by electrochemical reduction; the resulting liquid-gas counter flow in the porous transport layer results in liquid droplets being entrained in co-flow in the gas channels and convected downstream.

The equations of mass and momentum are solved by means of the open source software library OpenFOAM. A volume-of-fluid approach based on the multidimensional universal limiter for explicit solution was employed within a volume-of-fluid method. At T = 0, the channel is presumed to be filled with gas, and the PTL saturated with liquid water. Gas is introduced at the inlet at a given velocity. Water is added and gas removed at the electrode (counter flow) whereas both water and gas are removed at the outlet (coflow). At the channel and PTL walls as well as on the GDL fibres, the static contact angle was fixed. It can be seen that the location and size of the shed drops varies somewhat in space and time, i.e., there is a stochastic component to the motion of the fluid, due to the spatial distribution of the fibres in the PTL, the transient shedding process, and the merging of liquid streams flowing into the gas channel. Nonetheless, a definite periodicity is observed with drops being injected into the channel at a fairly regular rate. Some relatively minor switching with time is observed within the PTL due to the random packing of fibres, but again these transients are relatively quiescent, as might be expected for porous media flow.

In addition to providing new and important information about flow and pressure losses in channels and PTLs of electrochemical cells as a function of gas and liquid flow rates, i.e. current density and stoichiometry, the present model may be also used to enumerate properties such as relative permeability which can subsequently be employed in cell-scale models.

  • Lecture (Conference)
    PRiME 2020, 04.-09.10.2020, Honolulu, USA
  • Open Access Logo ECS Transactions 98(2020)9, 305-315
    DOI: 10.1149/09809.0305ecst

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Permalink: https://www.hzdr.de/publications/Publ-31029
Publ.-Id: 31029


Nanopatterning of the (001) surface of crystalline Ge by ion irradiation at off-normal incidence: Experiment and simulation

Erb, D.; de Schultz, R.; Ilinov, A.; Nordlund, K.; Bradley, M. R.; Facsko, S.

Intricate topographical patterns can form on the surface of crystalline Ge(001) subject to low-energy ion irradiation in the reverse epitaxy regime, i.e., at elevated temperatures which enable dynamic recrystallization. We compare such nanoscale patterns produced by irradiation from varied polar and azimuthal ion incidence angles with corresponding calculated surface topographies. To this end, we propose a continuum equation including both anisotropic erosive and anisotropic diffusive effects. Molecular dynamics simulations provide the coefficients of angle-dependent sputter erosion for the calculations. By merely changing these coefficients accordingly, the experimentally observed surface morphologies can be reproduced, except for extreme ion incidence angles. Angle-dependent sputter erosion is thereby identified as a dominant mechanism in ion-induced pattern formation on crystalline surfaces under irradiation from off-normal incidence angles.

Keywords: Ion impact & scattering; Surface diffusion; Surface instabilities; Nanostructures; Vacuum interfaces; Molecular dynamics; Atomic force microscopy

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Permalink: https://www.hzdr.de/publications/Publ-31027
Publ.-Id: 31027


Visualizing Magnetic Structure in 3D Nanoscale Ni–Fe Gyroid Networks

Llandro, J.; Love, D. M.; Kovács, A.; Caron, J.; Vyas, K. N.; Kakay, A.; Salikhov, R.; Lenz, K.; Faßbender, J.; Scherer, M. R. J.; Cimorra, C.; Steiner, U.; Barnes, C. H. W.; Dunin-Borkowski, R. E.; Fukami, S.; Ohno, H.

Arrays of interacting 2D nanomagnets display unprecedented electromagnetic properties via collective effects, demonstrated in artificial spin ices and magnonic crystals. Progress toward 3D magnetic metamaterials is hampered by two challenges: fabricating 3D structures near intrinsic magnetic length scales (sub-100 nm) and visualizing their magnetic configurations. Here, we fabricate and measure nanoscale magnetic gyroids, periodic chiral networks comprising nanowire-like struts forming three-connected vertices. Via block copolymer templating, we produce Ni75Fe25 single-gyroid and double-gyroid (an inversion pair of single-gyroids) nanostructures with a 42 nm unit cell and 11 nm diameter struts, comparable to the exchange length in Ni–Fe. We visualize their magnetization distributions via off-axis electron holography with nanometer spatial resolution and interpret the patterns using finite-element micromagnetic simulations. Our results suggest an intricate, frustrated remanent state which is ferromagnetic but without a unique equilibrium configuration, opening new possibilities for collective phenomena in magnetism, including 3D magnonic crystals and unconventional computing.

Keywords: magnetic metamaterials gyroids transmission electron microscopy off-axis electron holography

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-31026
Publ.-Id: 31026


Electron Concentration Limit in Ge Doped by Ion Implantation and Flash Lamp Annealing

Prucnal, S.; Żuk, J.; Hübner, R.; Duan, J.; Wang, M.; Pyszniak, K.; Drozdziel, A.; Turek, M.; Zhou, S.

Controlled doping with an effective carrier concentration higher than 10^20 cm-3 is a key challenge for the full integration of Ge into silicon-based technology. Such a highly doped layer of both p- and n type is needed to provide ohmic contacts with low specific resistance. We have studied the effect of ion implantation parameters i.e., ion energy, fluence, ion type, and protective layer on the effective concentration of electrons. We have shown that the maximum electron concentration increases as the thickness of the doping layer decreases. The degradation of the implanted Ge surface can be minimized by performing ion implantation at temperatures that are below -100 C with ion flux less than 60 nAcm-2 and maximum ion energy less than 120 keV. The implanted layers are flash-lamp annealed for 20 ms in order to inhibit the diffusion of the implanted ions during the recrystallization process.

Keywords: Ge; ion implantation; flash lamp annealing; n-type doping; Raman spectroscopy

Permalink: https://www.hzdr.de/publications/Publ-31025
Publ.-Id: 31025


Hydrogel-based Janus Micromotors Capped with Functional Nanoparticles for Environmental Applications

Lin, X.; Zhu, H.; Zhao, Z.; You, C.; Kong, Y.; Zhao, Y.; Liu, J.; Chen, H.; Shi, X.; Makarov, D.; Mei, Y.

Janus nano/micromotors have been developed into various sizes, shapes and functions for a blaze of applications especially in biomedical and environmental fields. Here, we report a fabrication method of Janus micromotors by capping hydrogel microspheres with functional nanoparticles (NPs). Microspheres are prepared in droplet microfluidics relying on hydrogel polymerization to obtain spheres with diameters from 20 μm to 500 μm. By solidifying a hydrogel layer onto microspheres, functional NPs of MnO2 (catalyst of H2O2), TiO2 (photocatalyst) and Fe3O4 (magnetic guidance) are adhered onto microspheres resulting in Janus micromotors revealing different functionalities. We explore dynamics of Janus micromotors (diameter around 250 µm) by analyzing their trajectories in terms of mean squared displacement (MSD) when immersed in H2O2 solutions of different concentrations, illuminated by light and guided in an external magnetic field. TiO2 Janus micromotors perform well for water purification tasks as we exemplarily demonstrate with a degradation of Methylene Blue dye in water. The proposed fabrication method is versatile and enables to achieve adjustable coverage of a microsphere with NPs as well as to realize multi-functional Janus micromotors by adhering different NPs (e.g., MnO2 and Fe3O4) on a sphere. This method provides an attractive way to fabricate multifunctional Janus micromotors in a cost-effective manner for environmental applications.

Keywords: Janus micromotors; photocurable hydrogel; functional nanoparticles; catalytic motion; environmental applications

Permalink: https://www.hzdr.de/publications/Publ-31023
Publ.-Id: 31023


High-field magnetoacoustics of a Dy2Fe14Si3 single crystal

Andreev, A. V.; Gorbunov, D.; Nomura, T.; Zvyagin, A. A.; Zvyagina, G. A.; Zherlitsyn, S.

Dy2Fe14Si3 (hexagonal crystal structure of the Th2Ni17 type) is a highly-anisotropic ferrimagnet with spontaneous magnetic moment Ms=8µB per formula unit (at 2 K), directed along the Fe sublattice, and Curie temperature TC=500 K. The magnetic anisotropy is of the easy-plane type with the [100] axis as an easy magnetization direction. Large anisotropy is observed also within the basal plane. In fields applied along the [100] and [120] axes, field-induced phase transitions were observed at 33 T (of thefirst order) and at 41 T (of the second order), respectively (at 2 K). Relative changes of sound velocity and changes of sound attenuation at these phase transitions in a Dy2Fe14Si3 single crystal were measured in pulsed magneticfields up to 58 T at 2 K and elevated temperatures. The performed theoretical analysis suggests that the interaction of the elastic subsystem with the magnetic one is of the exchange-striction nature.

Permalink: https://www.hzdr.de/publications/Publ-31022
Publ.-Id: 31022


Once daily versus radiotherapy in the management of limited disease small cell lung cancer - Decision criteria in routine practice

Glatzer, M.; Faivre-Finn, C.; de Ruysscher, D.; Widder, J.; van Houtte, P.; Troost, E. G. C.; Dahele, M.; Slotman, B.; Ramella, S.; Pöttgen, C.; Peeters, S.; Nestle, U.; Mcdonald, F.; Le Pechoux, C.; Dziadziuszko, R.; Belderbos, J.; Putora, P.

Background: In limited disease small cell lung cancer, the convert trial has demonstrated similar results with once-daily (QD) radiotherapy (66 Gy) and twice-daily (BID) radiotherapy (45 Gy). The selection among these regimes may be influenced by several factors. Methods: Thirteen European radiotherapy experts in SCLC as defined by the European Society for Therapeutic Radiation Oncology (ESTRO) were asked to describe their strategies in the management of LD-SCLC. The decision criteria were unified, the strategies were converted into decision trees and analysed for consensus and discrepancies. Results: Logistical reasons, performance status of the patient and dose constraints were the three major decision criteria used by most experts in decision making. The use of QD and BID regimes was balanced among European experts, but there was a trend towards the BID regime for fit patients able to travel twice a day to the radiotherapy site. Conclusion: BID and QD radiotherapy are both accepted treatment options among experts and the decision may be influenced by pragmatic factors such as availability of transportation.

Permalink: https://www.hzdr.de/publications/Publ-31021
Publ.-Id: 31021


Individual patient data meta-analysis of FMISO and FAZA hypoxia PET scans from head and neck cancer patients undergoing definitive radio-chemotherapy

Zschaeck, S.; Löck, S.; Hofheinz, F.; Zips, D.; Mortensen, L.; Zöphel, K.; Troost, E. G. C.; Boeke, D.; Saksoe, M.; Mönnich, D.; Seidlitz, A.; Johansen, J.; Skripcak, T.; Gregoire, V.; Overgaard, J.; Baumann, M.; Krause, M.

Background and purpose: Tumor hypoxia plays an important role in head and neck squamous cell carcinomas (HNSCC). Various positron emission tomography (PET) tracers promise non-invasive assessment of tumor hypoxia. So far, the applicability of hypoxia PET is hampered by monocentric imaging trials with few patients.
Materials and methods: Multicenter individual patient data based meta-analysis of the original PET data from four prospective imaging trials was performed. All patients had localized disease and were treated with curatively intended radio(-chemo)therapy. Hypoxia PET imaging was performed with 18F-Fluoromisonidazole (FMISO, 102 patients) or 18F-Fluoroazomycin-arabinoside (FAZA, 51 patients). Impact of hypoxia PET parameters on loco-regional control (LRC) and overall survival (OS) was analyzed by uni- and multivariable Cox regression.
Results: Baseline characteristics between participating centers differed significantly, especially regarding T stage (p<0.001), tumor volume (p<0.001) and p16 status (p=0.009). The commonly used hypoxia parameters, maximal tumor-to-muscle ratio (TMRmax) and hypoxic volume with 1.6 threshold (HV1.6), showed a strong association with LRC (p=0.001) and OS (p<0.001).
These findings were irrespective of the radiotracer and the same cut-off values could be applied for FMISO and FAZA (TMRmax>2.0 or HV1.6>1.5 ml). The effect size of TMRmax was similar for subgroups of patients defined by radiotracer, p16 status and FDG-PET parameters for LRC and OS, respectively.
Conclusion: PET measured hypoxia is robust and has a strong impact on LRC and OS in HNSCC. The most commonly investigated tracers FMISO and FAZA can probably be used equivalently in multicenter trials. Optimal strategies to improve the dismal outcome of hypoxic tumors remain elusive.

Keywords: head and neck cancer; FMISO; FAZA; PET; hypoxia

Permalink: https://www.hzdr.de/publications/Publ-31020
Publ.-Id: 31020


Bentonite Geomicrobiology

Lopez Fernandez, M.; Matschiavelli, N.; Merroun, M. L.

Bentonites may be used as a buffer and backfill material in future deep geological repositories of high-level radioactive waste. These clay formations have been reported to host different metabolically active microorganisms with the potential to affect the biogeochemical cycles of carbon, phosphorus and sulfur. Therefore, low porosity bentonites with high swelling capacity might prevent several microbial processes, such as corrosion. In addition, microorganisms occurring in bentonite may be able to interact with released radionuclides affecting their fate and behavior and leading to their mobilization or immobilization.
This chapter reviews the latest findings on the structure and composition of microbial communities in bentonites under repository relevant conditions (high temperature, high pressure, presence of electron donors/acceptors, etc.), to underline the importance of the microbial activity for the long-term effectiveness of the repository. Both, laboratory and large-scale experiment results will be summarized and discussed. In addition, the impact of microbial processes on the mobilization of radionuclides at the bentonite/microbe/radionuclide interface will be reviewed. A multidisciplinary approach combining microscopy, spectroscopy, radiochemistry and microbiology-based techniques used to study the speciation of radionuclides will be highlighted.

Keywords: bentonite; microbial diversity; microbial activity; microbial radionuclide migration; high-level radioactive waste; deep geological repository

  • Book chapter
    Jonathan R. Lloyd, Andrea Cherkouk: The Microbiology of Nuclear Waste Disposal, Netherlands: Elsevier, 2020, 978-0-12-818695-4, 137-155

Permalink: https://www.hzdr.de/publications/Publ-31019
Publ.-Id: 31019


Multi Optical Sensor Fusion for Mineral Mapping of Core Samples

Rasti, B.; Ghamisi, P.; Seidel, P.; Lorenz, S.; Gloaguen, R.

Geological objects are characterized by a high complexity inherent to a strong compositional variability at all scales and usually unclear class boundaries. Therefore, dedicated processing schemes are required for the analysis of such data for mineral mapping. On the other hand, the variety of optical sensing technology reveals different data attributes and therefore multi-sensor approaches are adapted to solve such complicated mapping problems. In this paper, we devise an adapted multi-optical sensor fusion (MOSFus) workflow which takes the geological characteristics into account. The proposed processing chain exhaustively covers all relevant stages, including data acquisition, preprocessing, feature fusion, and mineral mapping. The concept includes i) a spatial feature extraction based on morphological profiles on RGB data with high spatial resolution, ii) a specific noise reduction applied on the hyperspectral data that assumes mixed sparse and Gaussian contamination and iii) a subsequent dimensionality reduction using a sparse and smooth low rank analysis. The feature extraction approach allows to fuse heterogeneous data at variable resolutions, scales, and spectral ranges as well as improve classification substantially. The last step of the approach, an SVM classifier, is robust to unbalanced and sparse training sets and is particularly efficient with complex imaging data. We evaluate the performance of the procedure with two different multi-optical sensor datasets. The results demonstrate the superiority of this dedicated approach over common strategies.

Keywords: Multi-sensor data; optical sensor; hyperspectral; hyperspectral mixed sparse and Gaussian noise reduction (HyMiNoR); spectral imaging; data fusion; feature extraction; dimensionality reduction; support vector machine (SVM); sparse and smooth low-rank analysis (SSLRA); orthogonal total variation component analysis (OTVCA); mineral exploration

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Permalink: https://www.hzdr.de/publications/Publ-31017
Publ.-Id: 31017


Quantum and classical phase-space dynamics of a free-electron laser

Carmesin, C. M.; Peter, K.; Enno, G.; Sauerbrey, R.; Schleich, W. P.

In a quantum mechanical description of the free-electron laser (FEL), the electrons jump on discrete momentum ladders, while they follow continuous trajectories according to the classical description. In order to observe the transition from quantum to classical dynamics, it is not sufficient that many momentum levels are involved. Only if additionally the initial momentum spread of the electron beam is larger than the quantum mechanical recoil, caused by the emission and absorption of photons, the quantum dynamics in phase space resembles the classical one. Beyond these criteria, quantum signatures of averaged quantities like the FEL gain might be washed out.

Permalink: https://www.hzdr.de/publications/Publ-31016
Publ.-Id: 31016


Crystal Growth of Spin-frustrated Ba4Nb0.8Ir3.2O12: A Possible Spin Liquid Material

Thakur, G. S.; Chattopadhyay, S.; Doert, T.; Herrmannsdörfer, T.; Felser, C.

Polycrystalline Ba4NbIr3O12 has recently been shown to be a promising spin liquid candidate. We report an easy and reliable method to grow millimeter-sized single crystals of this trimer-based spin liquid candidate material with the actual stoichiometry of Ba4Nb0.8Ir3.2O12. The growth of large crystals is achieved using BaCl as flux. The crystals show a hexagonal platelike habit with edges up to 3 mm in length. The structure is confirmed by single-crystal X-ray diffraction and is found to be the same as that of the previously reported phase Ba12Nb2.4Ir9.6O36 [Ba4Nb0.8Ir3.2O12], indeed with a mixed occupancy of Nb/Ir at the 3a site. The magnetic and calorimetric study on the individual single crystals confirms the possibility of a spin liquid state consistent with a recent report on a polycrystalline sample.

Permalink: https://www.hzdr.de/publications/Publ-31014
Publ.-Id: 31014


Two-fluid model simulations of isothermal stratified counter-current flow of air and water with interface compression and turbulence damping

Tekavčič, M.; Meller, R.; Schlegel, F.; Končar, B.

Stratified flows of water and steam can appear in the primary system of a pressurized water reactor during a hypothetical loss-of-coolant accident. Among others, important safety concerns during cold water injection of the emergency core cooling system include the pressurized thermal shock and the possible formation of a condensation induced water hammer. Both mechanisms could cause significant thermal and mechanical stresses on the components of the primary system. Thorough knowledge of turbulent heat and mass transfer processes near the interface is required for safety analyses of both phenomena.
Measurements of industrially relevant turbulent two-phase flows tend to be difficult; therefore computational fluid dynamics simulations represent an important additional analytical tool. The main objective of the present research and development is to advance the capabilities of current state-of-the-art modeling tools towards the simulations of two-phase flow phenomena under realistic reactor conditions. In the present paper, the focus is on turbulence modelling near the gas liquid interface in stratified flows.
An isothermal stratified counter-current flow of air and water in a rectangular channel is simulated. Computational domain and boundary conditions are based on the flow conditions in the test section of the WENKA experiment [1]. The validation case considers supercritical stratified flow with Froude number of 2.36 and Reynolds number 12000 for water and 27000 for air.
The two-fluid modeling approach with interface compression is used to resolve the interface between the two phases. A consistent momentum interpolation numerical scheme is applied, featuring the partial elimination algorithm to handle the strong interphase drag coupling at a resolved interface. The Unsteady Reynolds Averaged Navier-Stokes (URANS) approach is used to describe turbulent two-phase flow. Modelling of turbulence dissipation at the interface requires a special treatment that includes introduction of additional turbulence damping terms into the k-ω Shear Stress Transport (SST) turbulence equations. Simulations, model and source code development are performed with the open source C++ library OpenFOAM.
Simulation results are validated with the measured profiles of volume fraction, velocity and turbulent kinetic energy at two streamwise positions in the test section of the WENKA experiment. Results of the mesh sensitivity study are presented. Furthermore, results of a parametric study reveal that an asymmetric damping approach with a lower coefficient on the liquid side of the interface can improve the prediction of turbulent kinetic energy profiles.

[1] Stäbler, T., Meyer, L., Schulenberg, T., & Laurien, E. (2006). Turbulence Structures in Horizontal Two-Phase Flows Under Counter-Current Conditions. Proceedings of FEDSM2006 (pp. 61–66). ASME.

  • Lecture (Conference)
    International Conference Nuclear Energy for New Europe NENE2020, 07.-10.09.2020, Portorož, Slovenia
  • Contribution to proceedings
    International Conference Nuclear Energy for New Europe, 07.-10.09.2020, Portorož, Slovenia,
    Two-fluid Model Simulations of Isothermal Stratified Counter-current Flow of Air and Water with Interface Compression and Turbulence Damping, 715.1-715.9

Permalink: https://www.hzdr.de/publications/Publ-31013
Publ.-Id: 31013


Fermion sign problem in path integral Monte Carlo simulations: Quantum dots, ultracold atoms, and warm dense matter

Dornheim, T.

The ab initio thermodynamic simulation of correlated Fermi systems is of central importance for many applications, such as warm dense matter, electrons in quantum dots, and ultracold atoms. Unfortunately, path integral Monte Carlo (PIMC) simulations of fermions are severely restricted by the notorious fermion sign problem (FSP). In this paper, we present a hands-on discussion of the FSP and investigate in detail its manifestation with respect to temperature, system size, interaction-strength and -type, and the dimensionality of the system. Moreover, we analyze the probability distribution of fermionic expectation values, which can be non-Gaussian and fat-tailed when the FSP is severe. As a practical application, we consider electrons and dipolar atoms in a harmonic confinement, and the uniform electron gas in the warm dense matter regime. In addition, we provide extensive PIMC data, which can be used as a reference for the development of new methods and as a benchmark for approximations.

Keywords: path integral Monte Carlo; statistical physics; sign problem; computational physics

Permalink: https://www.hzdr.de/publications/Publ-31012
Publ.-Id: 31012


Natural convection heat transfer performance of additively manufactured tube bundle heat exchangers with novel fin design

Unger, S.; Beyer, M.; Pietruske, H.; Szalinski, L.; Hampel, U.

These are the raw data and the processed data of the journal paper " Natural convection heat transfer performance of additively manufactured tube bundle heat exchangers with novel fin desigs".

The raw data contains the measured values on the experimental setup and the processed data contains the data of the data used in the corresponding journal publication.

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  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-05-10
    DOI: 10.14278/rodare.319
    License: CC-BY-4.0

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Publ.-Id: 31011


DNA damage in human whole blood caused by radiopharmaceuticals evaluated by the comet assay

Schmeiser, H.; Muehlbauer, K.; Mier, W.; Baranski, A.; Neels, O.; Dimitrakopolou-Strauss, A.; Schmezer, P.; Kratochwil, C.; Bruchertseifer, F.; Morgenstern, A.; Kopka, K.

Radiopharmaceuticals used for diagnosis or therapy induce DNA strand breaks, which may be detectable by single-cell gel electrophoresis (called comet assay). Blood was taken from patients before and at different time points after treatment with radiopharmaceuticals; blood cells were investigated by the comet assay using the percentage of DNA in the tail as the critical parameter. Whereas [225Ac]Ac-prostate-specific membrane antigen (PSMA)-617 alpha therapy showed no difference relative to the blood sample taken before treatment, beta therapy with [177Lu]Lu-PSMA-617 3 h post-injection revealed a small but significant increase in DNA strand breaks. In blood of patients who underwent positron emission tomography (PET) with either [18F]2-fluor-2-deoxy-D-glucose (FDG) or [68Ga]Ga-PSMA-11, an increase of DNA migration determined by the comet assay was not found when analysed at different time points (2–70 min) after intravenous tracer injection. Human whole blood was incubated with the targeted clinically relevant therapeutic radiopharmaceuticals [225Ac]Ac-PSMA-617, [177Lu]Lu-PSMA-617 and [90Y]Y-DOTA(0)-Phe(1)-Tyr(3)-octreotide (DOTA-TOC) at different activity concentrations (kBq/ml) for 5 days and then analysed by the comet assay. DNA damage increased with higher concentrations of all radiolabeled compounds tested. [177Lu]Lu-PSMA-617 caused higher blood cell radiotoxicity than equal activity concentrations of 90Y]Y-DOTATOC. Likewise, whole human blood was exposed to the positron emitters [18F]FDG and [68Ga]Ga-PSMA-11 in vitro for 24 h with activity concentrations ranging between 5 and 40 MBq/ml. The same activity concentration dependent elevated DNA migration was observed for both compounds although decay energies are different. This study demonstrated that the amount of DNA damage detected by the comet assay in whole human blood is similar among different positron emitters and divergent by a factor of 200 between alpha particles and beta radiation.

Permalink: https://www.hzdr.de/publications/Publ-31010
Publ.-Id: 31010


Using simultaneous x-ray diffraction and velocity interferometry to determine material strength in shock-compressed diamond

Macdonald, M. J.; Mcbride, E. E.; Galtier, E.; Gauthier, M.; Granados, E.; Kraus, D.; Krygier, A.; Levitan, A. L.; Mackinnon, A. J.; Nam, I.; Schumaker, W.; Sun, P.; van Driel, T. B.; Vorberger, J.; Zhou, X.; Drake, R. P.; Glenzer, S. H.; Fletcher, L. B.

We determine the strength of laser shock-compressed polycrystalline diamond at stresses above the Hugoniot elastic limit using a novel technique combining x-ray diffraction from the Linac Coherent Light Source with velocity interferometry. X-ray diffraction is used to measure lattice strains and velocity interferometry is used to infer shock and particle velocities. These measurements, combined with density-dependent elastic constants calculated using density functional theory, enable determination of material strength above the Hugoniot elastic limit. Our results indicate that diamond retains approximately 20 GPa of strength at longitudinal stresses of 150–300 GPa under shock compression.

Keywords: diffraction; diamond; strength; high pressure; shock; Hugoniot

Permalink: https://www.hzdr.de/publications/Publ-31009
Publ.-Id: 31009


Natural convection heat transfer performance of additively manufactured tube bundle heat exchangers with novel fin design

Unger, S.; Beyer, M.; Pietruske, H.; Szalinski, L.; Hampel, U.

In many applications finned tube bundles are commonly used for heating or cooling purpose. Hence, the natural convection heat transfer from finned heat exchanger configurations with novel design in a chimney was experimentally studied. These novel fin designs use integrated pins to enhance the heat conduction from the fin base to the fin tip as well as the convective heat transfer along the fin surface. Oval tubes with conventional circular plain fins (CPF) as well as novel circular integrated pin fins (CIPF) and serrated integrated pin fins (SIPF) were additively generated by a Selective Laser Melting (SLM) process and installed at the bottom of a 6.5 m long chimney. All heat exchanger designs were tested in a 2-row and 3-row configuration with Rayleigh numbers between 25,000 and 120,000. We found the average Nusselt number of SIPF to be higher and the Nusselt number of the CIPF to be lower compared to the CPF. Furthermore, the 2-row configuration achieved greater Nusselt number compared to the 3-row configuration for all heat exchanger designs. The analysis of the individual tube rows showed highest Nusselt numbers at the first tube row and the lowest at the last tube row for both configurations. However, for the SIPF the difference between the first and second tube row is smaller compared to the CPF and CIPF. In order to evaluate the compactness of the heat exchanger, the volumetric heat flux density was applied. Similar to Nusselt number the volumetric heat flux density enhanced for the SIPF and reduced for the CIPF compared to the conventional design. Also the 2-row configuration reaches greater thermal performance compared to the 3-row configuration. Additionally, the surface area and the volume of the heat exchanger material are 30.7 % and 6.9 % lower for the SIPF compared to the CPF. The experimental outcome was used to develop an empirical heat transfer correlation between Nusselt number, Rayleigh number, fin design and tube row number.

Keywords: Novel heat exchanger designs; Natural convection; Heat transfer performance; Additive Manufacturing; Integrated pin fin

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Permalink: https://www.hzdr.de/publications/Publ-31008
Publ.-Id: 31008


Ab initio simulation of warm dense matter

Bonitz, M.; Dornheim, T.; Moldabekov, Z. A.; Zhang, S.; Hamann, P.; Kählert, H.; Filinov, A.; Ramakrishna, K.; Vorberger, J.

Warm dense matter (WDM) { an exotic state of highly compressed matter { has attracted high interest in recent years in astrophysics and for dense laboratory systems. At the same time, this state is extremely diffcult to treat theoretically. This is due to the simultaneous appearance of quantum degeneracy, Coulomb correlations and thermal effects, as well as the overlap of plasma and condensed phases. Recent breakthroughs are due to the successful application of density functional theory (DFT) methods which, however, often lack the necessary accuracy and predictive capability for WDM applications. The situation has changed with the availability of the first ab initio data for the exchange-correlation free energy of the warm dense uniform electron gas (UEG) that were obtained by quantum Monte Carlo (QMC) simulations, for recent reviews, see Dornheim et al., Phys. Plasmas 24, 056303 (2017) and Phys. Rep. 744, 1-86 (2018). In the present article we review recent further progress in QMC simulations of the warm dense UEG: namely, ab initio results for the static local field correction G(q) and for the dynamic structure factor S(q; w). These data are of key relevance for the comparison with x-ray scattering experiments at free electron laser facilities and for the improvement of theoretical models.
In the second part of this paper we discuss simulations of WDM out of equilibrium. The theoretical approaches include Born-Oppenheimer molecular dynamics, quantum kinetic theory, timedependent DFT and hydrodynamics. Here we analyze strengths and limitations of these methods and argue that progress in WDM simulations will require a suitable combination of all methods. A particular role might be played by quantum hydrodynamics, and we concentrate on problems, recent progress, and possible improvements of this method.

Keywords: warm dense matter; first principle simulation; DFT; DFT-MD; TD-DFT; QHD; QMC; PIMC; XRTS; exchange; correlation; xc functional; response function

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Permalink: https://www.hzdr.de/publications/Publ-31007
Publ.-Id: 31007


Gallium-68 Complex of a Macrobicyclic Cage Amine Chelator Tethered to Two Integrin-Targeting Peptides for Diagnostic Tumor Imaging

Ma, M.; Neels, O.; Denoyer, D.; Roselt, P.; Karas, J.; Scanlon, D.; White, J.; Hicks, R.; Donnelly, P.

Tumor-targeting peptides radiolabeled with positron-emitting 68Ga are promising candidates as new noninvasive diagnostic agents for positron emission tomography (PET). The targeting peptides are tethered to a chelator that forms a stable coordination complex with Ga3+ that is inert to dissociation of Ga3+in vivo. Metal complexes of macrobicyclic hexaamine “sarcophagine” (sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane) ligands exhibit remarkable stability as a result of the encapsulating nature of the cage amine ligand. A Ga3+ sarcophagine complex, [Ga-(1-NH3-8-NH2-sar)]4+, has been characterized using X-ray crystallography, demonstrating that Ga3+ is coordinated to six nitrogen atoms in a distorted octahedral complex. A bifunctional derivative of (NH2)2sar, possessing two aliphatic linkers with carboxylic acid functional groups has been attached to two cyclic-RGD peptides that target the αvβ3 integrin receptor that is overexpressed in some types of tumor tissue. This dimeric species can be radiolabeled with 68Ga3+ in >98% radiochemical yield and 68Ga3+ does not dissociate from the ligand in the presence of transferrin, an endogenous protein with high affinity for Ga3+. Biodistribution and micro-PET imaging studies in tumor-bearing mice indicate that the tracer accumulates specifically in tumors with high integrin expression. The high tumor uptake is coupled with low nonspecific uptake and clearance predominantly through the kidneys resulting in high-quality PET images in animal models.

Permalink: https://www.hzdr.de/publications/Publ-31006
Publ.-Id: 31006


Initiierung klinischer Multicenter-Studien mit lokaler Radiotracer-Herstellung

Zippel, C.; Neels, O.; Hennrich, U.; Giesel, F.; Kopka, K.

Ziel des Aufsatzes ist es, wesentliche gesetzliche und regulatorische Aspekte zu beleuchten, die bei multizentrischen klinischen Prüfungen mit kurzlebigen PSMA-PET-Radiopharmaka im Hinblick auf die Etablierung einer dezentralen Herstellung des klinischen Prüfpräparats zu beachten sind. Solche prospektiven Studien spielen in der nuklearmedizinischen Forschung und Entwicklung eine zunehmend wichtige Rolle. Um PSMA-PET-Tracer mit kurzer Halbwertzeit für die Prostatakrebsdiagnostik weiter im behördlichen Zulassungsverfahren und schließlich im Gesundheitssystem etablieren zu können, schließen sich nuklearmedizinische Zentren zunehmend standortübergreifend zusammen, um in angemessener Zeit hierfür die notwendige Anzahl von Studienpatienten zu erreichen. Im Folgenden gehen wir auf das regulatorische Umfeld zur Herstellung von PSMA-PET-Radiopharmaka als klinisches Prüfpräparat (engl. Investigational Medicinal Product, IMP) ein, und führen am Beispiel der frühen multizentrischen klinischen Prüfung der Phasen-I und -II „[68Ga]Ga-PSMA-11 in high-risk Prostate Cancer“ wesentliche Aspekte an, die bei der Initiierung einer prospektiven Studie mit dezentraler PSMA-Tracer-Herstellung aus radiopharmazeutisch-organisatorischer Sicht zu berücksichtigen und im Vorfeld abzustimmen sind.

Keywords: Radiopharmaka-Herstellung; gute Herstellungspraxis; PSMA-Tracer; multizentrische Studie; prospektive klinische Prüfung; Qualitätsmanagement

Permalink: https://www.hzdr.de/publications/Publ-31005
Publ.-Id: 31005


Impact of 18F-PSMA-1007 Uptake in Prostate Cancer Using Different Peptide Concentrations: Preclinical PET/CT Study on Mice

Soeda, F.; Watabe, T.; Naka, S.; Liu, Y.; Horitsugi, G.; Neels, O.; Kopka, K.; Tatsumi, M.; Shimosegawa, E.; Giesel, F.; Hatazawa, J.

PET radioligands with low molar activity (MA) may underestimate the quantity of the target of interest because of competitive binding of the target with unlabeled ligand. The aim of this study was to evaluate the change in the whole-body distribution of 18F-PSMA-1007 targeting prostate-specific membrane antigen (PSMA) when solutions with different peptide concentrations are used. Methods: Mouse xenograft models of LNCaP (PSMA-positive prostate cancer) (n = 18) were prepared and divided into 3 groups according to the peptide concentration injected: a high-MA group (1,013 ± 146 GBq/μmol; n = 6), a medium-MA group (100.7 ± 23.1 GBq/μmol; n 5 6), and a low-MA group (10.80 ± 2.84 GBq/μmol; n = 6). Static PET scans were performed 1 h after injection (scan duration, 10 min). SUVmean in tumor and normal organs was compared by the multiple-comparison test. Immunohistochemical staining and Western blot analysis were performed to confirm expression of PSMA in tumor, salivary gland, and kidney. Results: The low-MA group (SUVmean, 1.12 ± 0.30) showed significantly lower uptake of 18F-PSMA-1007 in tumor than did the high-MA group (1.97 ± 0.77) and the medium-MA group (1.81 ± 0.57). On the other hand, in salivary gland, both the low-MA group (SUVmean, 0.24 ± 0.04) and the medium-MA group (0.57 ± 0.08) showed significantly lower uptake than the high MA group (1.27 ± 0.28). The tumor-to-salivary gland SUVmean ratio was 1.73 ± 0.55 in the high-MA group, 3.16 ± 0.86 in the medium-MA group, and 4.78 ± 1.29 in the low-MA group. The immunohistochemical staining and Western blot analysis revealed significant overexpression of PSMA in tumor and low expression in salivary gland and kidney. Conclusion: A decrease in the MA level of the injected 18F-PSMA-1007 solution resulted in decreased uptake in tumor and, to a greater degree, in normal salivary gland. Thus, there is a possibility of minimizing the adverse effects in salivary gland by setting an appropriate MA level in PSMA targeting therapy.

Keywords: 18F-PSMA-1007; peptide concentration; molar activity; prostate cancer; salivary gland

  • Open Access Logo Journal of Nuclear Medicine 60(2019), 1594-1599
    DOI: 10.2967/jnumed.118.223479
  • Lecture (Conference)
    Annual Congress of the European Association of Nuclear Medicine, October 13 – 17, 2018, Düsseldorf, Germany, 13.-17.10.2018, Düsseldorf, Deutschland
    DOI: 10.1007/s00259-018-4148-3

Permalink: https://www.hzdr.de/publications/Publ-31004
Publ.-Id: 31004


Production of Ga-68 radiotracers under GMP and regulatory aspects - a German perspective

Neels, O.

Radiopharmaceuticals labelled with the positron emitter Gallium-68 have had an enormous impact on the diagnostic imaging of neuroendocrine tumors using somatostatin receptor ligands and in recent years on the diagnosis of prostate cancer using PSMA ligands and subsequently their application for radioendotherapy using Yttrium-90, Lutetium-177 or more recently Actinium-225. The release of the monographs for ‘Gallium-68 chloride solution for radiolabelling’ and ‘Gallium-68 Edotreotide injection’ within the European Pharmacopoeia in 2013 tightened the requirements for specifications of Gallium-68 labelled radiotracers and will be enhanced with the ongoing elaboration of monographs for ‘Gallium-68 DOTA-TATE injection’, ‘Gallium-68 DOTA-NOC injection’ and ‘68Ga-PSMA’. In the same way the work environment of the responsible radiochemists and radiopharmacists in terms of quality control has been improved but also the workload has reached a high level with the increasing number of clinical applications and the limitation of the maximum achievable amount of starting activity from the currently available generators and therefore a limited dose number. The change of conditions for the production and quality control of Gallium-68 labelled radiopharmaceuticals will be reviewed with regards to legislating and practical aspects from ‘on bench’ to ‘full GMP’ preparation linked to the specific requirements for a multi-centre clinical trial using 68Ga-PSMA-11 in high-risk prostate cancer.

  • Open Access Logo Invited lecture (Conferences)
    4th Theranostics World Congress 2016, 07.-09.11.2016, Melbourne, Australia
    DOI: 10.1530/endoabs.47.OC2

Permalink: https://www.hzdr.de/publications/Publ-31003
Publ.-Id: 31003


Thermal kinetics of free volume in porous spin-on dielectrics: exploring the network- and pore-properties

Elsherif, A. G. A.; Koehler, N.; Liedke, M. O.; Butterling, M.; Hirschmann, E.; Ecke, R.; Schulz, S. E.; Wagner, A.

Data to ULK-kinetics by Positron annihilation spectroscopy and Fourier transform infrared spectroscopy

Keywords: PALS, FTIR, ULK, Curing

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-05-11
    DOI: 10.14278/rodare.321
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-31002
Publ.-Id: 31002


Manipulation of [11C]-5-Hydroxytryptophan and 6-[18F]Fluoro-3,4-Dihydroxy-L-Phenylalanine Accumulation in Neuroendocrine Tumor Cells

Neels, O.; Koopmans, K.; Jager, P.; Vercauteren, L.; van Waarde, A.; Doorduin, J.; Timmer-Bosscha, H.; Brouwers, A.; de Vries, E.; Dierckx, R.; Kema, I.; Elsinga, P.

[11C]-5-Hydroxytryptophan ([11C]HTP) and 6-[18F]fluoro-3,4-dihydroxy-L-phenylalanine ([18F]FDOPA) are used to image neuroendocrine tumors with positron emission tomography. The precise mechanism by which these tracers accumulate in tumor cells is unknown. We aimed to study tracer uptake via large amino acid transporters, peripheral decarboxylation (inhibited by carbidopa), and intracellular breakdown by monoamine oxidase (MAO). [11C]HTP and [18F]FDOPA tracer accumulation was assessed in a human neuroendocrine tumor cell line, BON. The carbidopa experiments were done in a tumor-bearing mouse model. Intracellular [11C]HTP accumulation was 2-fold higher than that of [18F]FDOPA. Cellular transport of both tracers was inhibited by amino-2-norbornanecarboxylic acid. The MAO inhibitors clorgyline and pargyline increased tracer accumulation in vitro. Carbidopa did not influence tracer accumulation in vitro but improved tumor imaging in vivo. Despite lower accumulation in vitro, visualization of [18F]FDOPA is superior to [11C]HTP in the neuroendocrine pancreatic tumor xenograft model. This could be a consequence of the serotonin saturation of BON cells in the in vivo model.

Permalink: https://www.hzdr.de/publications/Publ-31001
Publ.-Id: 31001


Staging of carcinoid tumours with 18F-DOPA PET: a prospective, diagnostic accuracy study

Koopmans, K.; de Vries, E.; Kema, I.; Elsinga, P.; Neels, O.; Sluiter, W.; van der Horst-Schrivers, A.; Jager, P.

To assess individual treatment options for patients with carcinoid tumours, accurate knowledge of tumour localisation is essential. We aimed to test the diagnostic sensitivity of 6-[fluoride-18]fluoro-levodopa (18F-DOPA PET), compared with conventional imaging methods, in patients with carcinoid tumours. In a prospective, single-centre, diagnostic accuracy study, 18F-DOPA PET with carbidopa pretreatment was compared with somatostatin-receptor scintigraphy (SRS), CT, and combined SRS and CT in 53 patients with a metastatic carcinoid tumour. The performance of all imaging methods was analysed for individual patients, for eight body regions, and for the detection of individual lesions. PET and CT images were fused to improve localisation. To produce a composite reference standard, we used cytological and histological findings; all imaging tests, including secondary assessments for newly found lesions; follow-up; and biochemical data. Sensitivities were calculated and compared. In patient-based analysis, we recorded sensitivities of 100% (95% CI 93-100) for 18F-DOPA-PET, 92% (82-98) for SRS, 87% (75-95) for CT, and 96% (87-100) for combined SRS and CT (p=0.45 for 18F-DOPA PET vs combined SRS and CT). However, 18F-DOPA PET detected more lesions, more positive regions, and more lesions per region than combined SRS and CT. In region-based analysis, sensitivity of 18F-DOPA PET was 95% (90-98) versus 66% (57-74) for SRS, 57% (48-66) for CT, and 79% (70-86) for combined SRS and CT (p=0.0001, PET vs combined SRS and CT). In individual-lesion analysis, corresponding sensitivities were 96% (95-98), 46% (43-50), 54% (51-58), and 65% (62-69; p<0.0001 for PET vs combined SRS and CT). If the improved tumour localisation seen with 18F-DOPA-PET compared with conventional imaging is confirmed in future studies, this imaging method could replace use of SRS, help improve prediction of prognosis, and be used to assess patients' response to treatment for carcinoid tumours.

Permalink: https://www.hzdr.de/publications/Publ-31000
Publ.-Id: 31000


Improved Staging of Patients With Carcinoid and Islet Cell Tumors With 18F-Dihydroxy-Phenyl-Alanine and 11C-5-Hydroxy-Tryptophan Positron Emission Tomography

Koopmans, K.; Neels, O.; Kema, I.; Elsinga, P.; Sluiter, W.; Vanghillewe, K.; Brouwers, A.; Jager, P.; de Vries, E.

Purpose
To evaluate and compare diagnostic sensitivity of positron emission tomography (PET) scanning in carcinoid and islet cell tumor patients with a serotonin and a catecholamine precursor as tracers.
Patients and Methods
Carcinoid (n = 24) or pancreatic islet cell tumor (n = 23) patients with at least one lesion on
conventional imaging including somatostatin receptor scintigraphy (SRS) and computed tomography (CT) scan underwent 11C-5-hydroxytryptophan (11C-5-HTP) PET and 6-[F-18]fluoro-L-dihydroxyphenylalanin (18F-DOPA) PET. PET findings were compared with a composite reference standard derived from all available imaging along with clinical and cytologic/histologic information.
Results
In carcinoid tumor patients, per-patient analysis showed sensitivities for 11C-5-HTP PET, 18F-DOPA PET, SRS, and CT of 100%, 96%, 86%, 96%, respectively, and in islet cell tumors of 100%, 89%, 78%, 87%, respectively. In carcinoid patients, per-lesion analysis revealed sensitivities for 11C-5-HTP PET, 11C-5-HTP PET/CT, 18F-DOPA PET, 18F-DOPA PET/CT, SRS, SRS/CT, and CT alone of, respectively, 78%, 89%, 87%, 98%, 49%, 73%, and 63% and in islet cell tumors of 67%, 96%, 41%, 80%, 46%, 77%, and 68%, respectively. In all carcinoid patients 18F-DOPA PET and 11C-5-HTP PET detected more lesions than SRS (P < .001). 11C-5-HTP PET was superior to 18F-DOPA PET in islet cell tumors (P < .0001). In all cases, CT improved the sensitivity of the nuclear scans.
Conclusion
18F-DOPA PET/CT is the optimal imaging modality for staging in carcinoid patients and 11C-5-HTP PET/CT in islet cell tumor patients.

Permalink: https://www.hzdr.de/publications/Publ-30999
Publ.-Id: 30999


Molecular imaging in neuroendocrine tumors: Molecular uptake mechanisms and clinical results

Koopmans, K.; Neels, O.; Kema, I.; Elsinga, P.; Links, T.; de Vries, E.; Jager, P.

Neuroendocrine tumors can originate almost everywhere in the body and consist of a great variety of subtypes. This paper focuses on molecular imaging methods using nuclear medicine techniques in neuroendocrine tumors, coupling molecular uptake mechanisms ofradiotracers with clinical results. A non-systematic review is presented on receptor based and metabolic imaging methods. Receptor-based imaging covers the molecular backgrounds of somatostatin, vaso-intestinal peptide (VIP), bombesin and cholecystokinin (CCK) receptors and their link with nuclear imaging. Imaging methods based on specific metabolic properties include meta-iodo-benzylguanide (MIBG) and dimercapto-sulphuric acid (DMSA-V) scintigraphy as well as more modern positron emission tomography (PET)-based methods using radio-labeled analogues of amino acids, glucose, dihydroxyphenylalanine (DOPA), dopamine and tryptophan. Diagnostic sensitivities are presented for each imaging method and for each neuroendocrine tumor subtype. Finally, a Forest plot analysis of diagnostic performance is presented for each tumor type in order to provide a comprehensive overview for clinical use.

Keywords: Neuroendocrine tumors; Review; Diagnostic imaging; Radiopharmaceuticals/diagnostic use; Positron emission tomography; Gamma camera imaging

Permalink: https://www.hzdr.de/publications/Publ-30998
Publ.-Id: 30998


Requirements and complexity: interprofessional cooperation within a prospective multicenter clinical trial using [68Ga]Ga-PSMA-11 - The German Cancer Consortium (DKTK) experience

Neels, O.; Zippel, C.; Biedenstein, S.; Giesel, F.; Kopka, K.

Aim/Introduction:
Prospective clinical trials are initiated within the field of nuclear medicine to translate the most promising radioligands into clinical routine [1]. A close cooperation and communication between experts from different fields is necessary for the efficiency and efficacy of the clinical trial which can then have a positive impact on the timely start of recruitment and subsequent patient inclusions [2].
Materials and Methods:
Given the exemplary phase 1/2 multi-center clinical trial ,,Ga-68-PSMA-11 in high-risk Prostate Cancer“ (NCT03362359) [3], we demonstrate how professions from clinical research, drug manufacturing and administration can be involved in the planning, preparation and realisation of prospective clinical trials in nuclear medicine. Organisational measures are derived to support the interprofessional cooperation within diagnostic prospective multicenter clinical trials.
Results:
Besides nuclear medicine physicians, urologists and pathologists, other professions like technicians and technologists (nuclear medicine, biology, chemistry), study nurses, radiochemists/-pharmacists and nursing staff are involved in the clinical setting. In addition, radiation safety officers, quality manager, clinical monitors, lawyers, data protection officers, project managers and study coordinators are embedded in the setting of in total eleven study sites in Germany, Austria and Switzerland.
Conclusion:
Interprofessional cooperation is of great importance for high-quality work in health care and re-search in general, as well as the accomplishment of prospective clinical trials in nuclear medicine in particular. Readiness to put oneself in the position of other professions, cooperation under no professional constraints, adequate time for mutual exchange, the ability and skills for interprofessional project management and an integral view on the required expertise by strengthening overall communication skills are required in particular on senior management level.
References:
1. Zippel C, Ronski SC, Bohnet-Joschko S, Giesel FL, Kopka K. Current Status of PSMA-Radiotracers for Prostate Cancer: Data Analysis of Prospective Trials Listed on ClinicalTrials.gov. Pharmaceuticals (Basel, Switzerland). 2020;13.doi:10.3390/ph13010012.
2. Reeves S, Pelone F, Harrison R, Goldman J, Zwarenstein M. Interprofessional collaboration to improve professional practice and healthcare outcomes. The Cochrane database of systematic reviews. 2017;6:Cd000072. doi:10.1002/14651858.CD000072.pub3.
3. Neels O, Zippel C, Giesel F, Kopka K. Initiation Of A Prospective Clinical Multicentre Trial With Local Production Of A Short-Lived PSMA-PET-Radiopharmaceutical In The D-A-CH-Region: Chances And Experiences. Annual Congress of the European Association of Nuclear Medicine October 12 - 16, 2019. 2019;46:S732. doi:10.1007/s00259-019-04486-2.

  • Poster (Online presentation)
    EANM 2020 - Annual Congress of the European Association of Nuclear Medicine, 17.-21.10.2020, Wien, Österreich
    DOI: 10.1007/s00259-020-04988-4
  • Abstract in refereed journal
    European Journal of Nuclear Medicine and Molecular Imaging 47(2020)Suppl. 1, S597-S598
    DOI: 10.1007/s00259-020-04988-4

Permalink: https://www.hzdr.de/publications/Publ-30997
Publ.-Id: 30997


The static local field correction of the warm dense electron gas: An ab initio path integral Monte Carlo study and machine learning representation

Dornheim, T.; Vorberger, J.; Groth, S.; Hoffmann, N.; Moldabekov, Z.; Bonitz, M.

The response of the uniform electron gas (UEG) to an external perturbation is of paramount importance for many applications. Recently, highly accurate results for the static density response function and the corresponding local field correction have been provided both for warm dense matter [J. Chem. Phys. 151, 194 104 (2019)] and strongly coupled electron liquid [Phys. Rev. B 101, 045 129 (2020)] conditions based on exact ab initio path integral Monte Carlo (PIMC) simulations. In the present work, we further complete our current description of the UEG by exploring the high energy density regime, which is relevant for, e.g. astrophysical applications and inertial confinement fusion experiments. To this end, we present extensive new PIMC results for the static density response in the range of 0.05 ≤ r s ≤ 0.5 and 0.85 ≤ θ ≤ 8.
These data are subsequently used to benchmark the accuracy of the widely used random phase approximation and the dielectric theory by Singwi, Tosi, Land, and Sjölander (STLS). Moreover, we compare our results to configuration PIMC data where they are available and find perfect agreement with a relative accuracy of 0.001 − 0.01%. All PIMC data are available online.

Keywords: uniform electron gas; path integral monte carlo; density response

Permalink: https://www.hzdr.de/publications/Publ-30996
Publ.-Id: 30996


Development of an Ionization Chamber for the Measurement of the 16O(n, alpha)13C Cross-Section at the CERN n_TOF Facility.

Urlaß, S.; Junghans, A.; Mingrone, F.; Hartmann, A.; Sobiella, M.; Stach, D.; Tassan-Got, L.; Weinberger, D.

The 16O(n, alpha)13 C reaction, as the inverse reaction of the astrophysically important 13C(alpha, n)16O reaction, is proposed to be measured at the neutron time-of-flight (nTOF) facility of CERN. To this purpose, a Double Frisch Grid Ionization Chamber (DFGIC) containing the oxygen atoms as a component in the counting gas has been developed and a prototype was constructed at Helmholtz-Zentrum Dresden-Rossendorf(HZDR), in Germany. The first in-beam tests of the detector have been performed in November 2017 in the first (EAR1) and in April 2018 in the second (EAR2) experimental areas of the nTOF facility.

Keywords: NIC2018; oxygen; n_alpha; 16O; O-16

  • Contribution to proceedings
    15th International Symposium on Nuclei in the Cosmos, 24.-29.06.2018, Assergi, Italien
    Proceedings of the 15th International Symposium on Nuclei in the Cosmos: Springer Proceedings in Physics, 978-3-030-13875-2, 457-460
    DOI: 10.1007/978-3-030-13876-9_89

Permalink: https://www.hzdr.de/publications/Publ-30995
Publ.-Id: 30995


Measurement of the 16O(n, alpha)13C cross-section using a Double Frisch Grid Ionization Chamber.

Urlaß, S.; Beyer, R.; Hammer, S.; Hartmann, A.; Junghans, A.; Kögler, T.; Lutz, B.; Mingrone, F.; Müller, S.; Römer, K.; Scheibler, D.; Stach, D.; Szücs, T.; Tassan-Got, L.; Turkat, S.; Wagner, A.; Weinberger, D.

The 16O(n,alpha)13C reaction was proposed to be measured at the neutron time-of-flight (n_TOF) facility of CERN. To this purpose, a Double Frisch Grid Ionization Chamber (DFGIC) containing the oxygen atoms as a component in the counting gas coupled with a switch device in order to prevent the charge collection from the so-called gamma-flash has been developed at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), in Germany.
The first 16O(n, alpha)13C measurement without seeing the charge of the γ-flash at n_TOF has been performed in November 2018. After the electronics did not suffer from the gamma-flash any more, another huge charge collection was discovered. Due to the high instantaneous flux at the n_TOF facility the amount of that induced charge from neutron induced background reactions was piling up so much that the recognition of 16O(n, alpha)13C reactions from that background was very difficult. For that reason another 16O(n, alpha)13C measurement at the time-of-flight facility nELBE at HZDR which has a low instantaneous flux, has been performed in April 2019. Both measurements from n_TOF and nELBE will be presented here.

Keywords: n_TOF; nELBE; ND2019; n_alpha; oxygen; 16O; O-16

Permalink: https://www.hzdr.de/publications/Publ-30994
Publ.-Id: 30994


Evaluation of response by FDG-PET/CT and diffusion weighted MRI after radiochemotherapy of pancreatic cancer – a non-randomized, monocentric phase II clinical trial – PaCa-DD-041 (Eudra-CT 2009-011968-11)

Zimmermann, C.; Distler, M.; Jentsch, C.; Blum, S.; Folprecht, G.; Zöphel, K.; Polster, H.; Troost, E. G. C.; Abolmaali, N.; Weitz, J.; Baumann, M.; Saeger, H.; Grützmann, R.

Background
Pancreatic cancer is a devastating disease with a five-year survival rate of 20-25%. As approximately only 20% of the patients diagnosed with pancreatic cancer are initially staged as resectable, it is necessary to evaluate new therapeutic approaches. Hence neoadjuvant (radio)chemotherapy is a promising therapeutic option, especially in patients with a borderline resectable tumor. The aim of this non-randomized, monocentric, prospective, phase II clinical study was to assess the prognostic value of functional imaging techniques, i.e., [18F]2-fluoro-2-deoxy-D-glucose positron emission tomography / computed tomography (FDG-PET/CT) and diffusion weighted magnetic resonance imaging (DW-MRI), prior to and during neoadjuvant radiochemotherapy.
Methods
Patients with histologically proven resectable, borderline resectable or irresectable non-metastatic pancreatic adenocarcinoma received induction chemotherapy followed by a neoadjuvant radiochemotherapy. Patients underwent FDG-PET/CT and DW-MRI including T1- and T2-weighted sequences prior to and after neoadjuvant chemotherapy as well as following induction radiochemotherapy. The primary endpoint was the evaluation of the response as quantified by the Standardized Uptake Value (SUV) measured with (FDG-PET). Response to treatment was evaluated by FDG-PET and DW-MRI during and after the neoadjuvant course. Morphologic staging was done using contrast-enhanced CT and contrast enhanced MRI to decide inclusion of patients and resectability after neoadjuvant therapy. In those patients undergoing subsequent surgery, imaging findings were correlated with those of the pathologic resection specimen.
Results
A total of 25 patients were enrolled in the study. The response rate measured by FDG-PET was 85% with a statistically significant decrease of the maximal Standardized Uptake Value (SUVmax) during therapy (p <0.001). Using the mean ADC, response was not detectable with DW-MRI. After neoadjuvant treatment 16 patients underwent surgery. In 12 (48%) patients a tumor resection could be performed. The median overall survival of all patients was 25 months (range: 7 – 38 months).
Conclusion
Based on these limited patient numbers, we could show that this trial design is feasible and that the neoadjuvant therapy regime was well tolerated. To evaluate the response to the combined therapy, FDG-PET/CT may be a reliable method. In contrast, the evaluation of the response using mean the mean ADC, DW-MRI did not show conclusive results.

Permalink: https://www.hzdr.de/publications/Publ-30993
Publ.-Id: 30993


PIMC data for the uniform electron gas in the high energy density regime

Dornheim, T.; Groth, S.
Researcher: Moldabekov, Zhandos; Researcher: Vorberger, Jan

PIMC data for the static density response obtained by Dornheim et al. (Plasma Phys. Control. Fusion, https://doi.org/10.1088/1361-6587/ab8bb4). These data can be freely used by other researchers and contain a README file with additional information.

Keywords: Path integral Monte Carlo, uniform electron gas

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-05-08
    DOI: 10.14278/rodare.317
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30992
Publ.-Id: 30992


Dose dependent cerebellar atrophy in glioma patients after radio(chemo)therapy

Raschke, F.; Seidlitz, A.; Wesemann, T.; Löck, S.; Jentsch, C.; Platzek, I.; Petr, J.; van den Hoff, J.; Kotzerke, J.; Beuthien-Baumann, B.; Baumann, M.; Linn, J.; Krause, M.; Troost, E. G. C.

Background and purpose:
Radiotherapy is a standard treatment option for high-grade gliomas. Cognitive impairment is a side effect associated with radiotherapy particularly in long-term survivors. Recent findings suggest involvement of the cerebellum in cognitive function. The goal of this study was therefore to investigate dose dependent cerebellar atrophy using prospective, longitudinal MR data from adult glioma patients who received radiotherapy.
Materials and methods:
Cerebellar volumes were measured using T1-weighted MR images from 91 glioma patients before radiotherapy and every three months thereafter. We calculated the average cerebellar volume change per year per Gy, based on the mean cerebellar dose, using linear regression analysis. Subsequently, patient age was investigated as a confounding factor using multiple linear regression analysis. The impact of chemotherapy was assessed separately in a subgroup of patients receiving a cerebellar dose ≤ 1 Gy. Cerebellar mean dose and cerebellar volume changes were compared between patients treated with proton (N = 38) and photon therapy (N = 52).
Results:
Cerebellar volume decreased 2.4 % per 10 Gy per year (p < 0.001). The cerebellar volume loss was progressive over time without signs of recovery within the observational period of two years. Neither patient age (p = 0.27) nor chemotherapy (p = 0.43) had a significant impact on cerebellar atrophy. Compared to patients treated with photons, the cerebellar dose was significantly lower in patients treated with proton therapy (p < 0.001, r = 0.62) which also translated to a significantly lower cerebellar volume reduction per year (p = 0.016, r = 0.25).
Conclusion:
Cerebellar volume decreased significantly and irreversibly after radiotherapy as function of time and dose. Further work is now needed to correlate these results with cognitive function and motor performance.

Keywords: cerebellum; radiotherapy; atrophy; volume; proton therapy

Permalink: https://www.hzdr.de/publications/Publ-30991
Publ.-Id: 30991


Ab initio path integral Monte Carlo simulation of the uniform electron gas in the high energy density regime

Dornheim, T.; Moldabekov, Z.; Vorberger, J.; Groth, S.

The response of the uniform electron gas (UEG) to an external perturbation is of paramount importance for many applications. Recently, highly accurate results for the static density response function and the corresponding local field correction have been provided both for warm dense matter [J. Chem. Phys.151,194104 (2019)] and strongly coupled electron liquid [Phys. Rev. B101, 045129 (2020)] conditions based on exact ab initio path integral Monte Carlo (PIMC) simulations. In the present work, we further complete our current description of the UEG by exploring the high energy density regime, which is relevant for, e.g., astrophysical applications and inertial confinement fusion experiments. To this end, we present extensive new PIMC results for the static density response in the range of 0.05≤rs≤0.5 and 0.85≤θ≤8. These data are subsequently used to benchmark the accuracy of the widely used random phase approximation and the dielectric theory by Singwi, Tosi, Land, and Sjölander (STLS). Moreover, we compare our results to configuration PIMC data where they are available and find perfect agreement with a relative accuracy of 0.001−0.01%. All PIMC data are available online.

Keywords: Uniform Electron Gas; Path Integral Monte Carlo; Density Response

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-30990
Publ.-Id: 30990


The baryon density of the Universe from an improved rate of deuterium burning

Mossa, V.; Stöckel, K.; Cavanna, F.; Ferraro, F.; Aliotta, M.; Barile, F.; Bemmerer, D.; Best, A.; Boeltzig, A.; Broggini, C.; Bruno, C. G.; Caciolli, A.; Chillery, T.; Ciani, G. F.; Corvisiero, P.; Csedreki, L.; Davinson, T.; Depalo, R.; Di Leva, A.; Elekes, Z.; Fiore, E. M.; Formicola, A.; Fülöp, Z.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, G.; Kievsky, A.; Imbriani, G.; Junker, M.; Kochanek, I.; Lugaro, M.; Marcucci, L. E.; Mangano, G.; Marigo, P.; Masha, E.; Menegazzo, R.; Pantaleo, F. R.; Paticchio, V.; Perrino, R.; Piatti, D.; Pisanti, O.; Prati, P.; Schiavulli, L.; Straniero, O.; Szücs, T.; Takacs, M. P.; Trezzi, D.; Viviani, M.; Zavatarelli, S.

Light elements were produced in the first few minutes of the Universe through a sequence of nuclear reactions known as Big Bang nucleosynthesis (BBN). Among the light elements produced during BBN, deuterium is an excellent indicator of cosmological parameters because its abundance is highly sensitive to the primordial baryon density and also depends on the number of neutrino species permeating the early Universe. Although astronomical observations of primordial deuterium abundance have reached percent accuracy3, theoretical predictions based on BBN are hampered by large uncertainties on the cross-section of the deuterium burning D(p,γ)3He reaction. Here we show that our improved cross-sections of this reaction lead to BBN estimates of the baryon density at the 1.6 percent level, in excellent agreement with a recent analysis of the cosmic microwave background7. Improved cross-section data were obtained by exploiting the negligible cosmic-ray background deep underground at the Laboratory for Underground Nuclear Astrophysics (LUNA) of the Laboratori Nazionali del Gran Sasso (Italy)8,9. We bombarded a high-purity deuterium gas target with an intense proton beam from the LUNA 400-kilovolt accelerator11 and detected the γ-rays from the nuclear reaction under study with a high-purity germanium detector. Our experimental results settle the most uncertain nuclear physics input to BBN calculations and substantially improve the reliability of using primordial abundances to probe the physics of the early Universe.

Permalink: https://www.hzdr.de/publications/Publ-30989
Publ.-Id: 30989


Setup commissioning for an improved measurement of the D(p,gamma)3He cross section at Big Bang Nucleosynthesis energies

Mossa, V.; Stöckel, K.; Cavanna, F.; Ferraro, F.; Aliotta, M.; Barile, F.; Bemmerer, D.; Best, A.; Boeltzig, A.; Broggini, C.; Bruno, C. G.; Caciolli, A.; Csedreki, L.; Chillery, T.; Ciani, G. F.; Corvisiero, P.; Davinson, T.; Depalo, R.; Di Leva, A.; Elekes, Z.; Fiore, E. M.; Formicola, A.; Fülöp, Z.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, G.; Imbriani, G.; Junker, M.; Kochanek, I.; Lugaro, M.; Marcucci, L. E.; Marigo, P.; Masha, E.; Menegazzo, R.; Pantaleo, F. R.; Paticchio, V.; Perrino, R.; Piatti, D.; Prati, P.; Schiavulli, L.; Straniero, O.; Szücs, T.; Takacs, M. P.; Trezzi, D.; Zavatarelli, S.; Zorzi, G.

Among the reactions involved in the production and destruction of deuterium during Big Bang Nucleosynthesis, the deuterium-burning D(p,γ)3He reaction has the largest uncertainty and limits the pre- cision of theoretical estimates of primordial deuterium abundance. Here we report the results of a careful commissioning of the experimental setup used to measure the cross-section of the D(p,γ)3He reaction at the Laboratory for Underground Nuclear Astrophysics of the Gran Sasso Laboratory (Italy). The commis- sioning was aimed at minimising all sources of systematic uncertainty in the measured cross sections. The overall systematic error achieved (< 3%) will enable improved predictions of BBN deuterium abundance.

Permalink: https://www.hzdr.de/publications/Publ-30987
Publ.-Id: 30987


ISO proposal: Measurement of Fluid Flow Rate in Closed Conduits – Radioactive Tracer Methods

Jentsch, T.; Thereska, J.; Brisset, P.; Jin, J. H.; Yunos, M. A. S. M.; Masinza, S. A.; Affum, H. A.

Radioactive tracer methods are very competitive and sometimes unique for online measurement of flow rate in single phase flows flowing inside closed conduits. Radioactive tracer methods are already well accepted from industrial end users and established in routine service worldwide.

ISO standards are basic elements of quality control and accreditation for recognition and cooperation in national and international market. There have been proposed several ISO standards dealing with radioactive tracer methods for measurement of water and gas flows in closed conduits during last five decades:

ISO 2975/VII Measurement of water flow in closed conduits -Tracer methods: Transit time method using radioactive tracers
ISO 4053 Measurement of gas flow in conduits -Tracer methods

The ISO standards ISO2975 and ISO4053 issued in 1975-1977 addressed radioactive tracer methods respectively for water and gas flows. The ISO2975 is limited to water phase only, while ISO4053 dealt with gas phase, was withdrawn in 2001 leaving a void on this subject. The proposed ISO standard will replace both of them.

This ISO proposal defines the use of radioactive tracer methods in the measurement of single-phase fluid (gas or liquid) flows in closed conduits. This method of measurement is applicable only to single-phase homogeneous fluid mixtures. This ISO proposal is developed to fill the need for a generalized reference based on fundamental principles to measure fluid flow using radioactive tracer methods. It defines the terms and principles needed for intelligent consideration of radioactive tracer methods for any single-phase fluid flow flowing in closed circuits.

Experts from different countries – so called P member states of ISO TC30 SC5 – will discuss the ISO proposal, and finalize it as new international standard in this field in coming years.

Keywords: ISO standard; radioactive tracer; radiotracer; measurement; fluid flow rate; closed conduits

  • Lecture (Conference)
    NUTECH-2020, 04.-07.10.2020, Warszawa, Polska

Permalink: https://www.hzdr.de/publications/Publ-30984
Publ.-Id: 30984


Development of a reliable remote-controlled synthesis of β-[11C]-5-hydroxy-L-tryptophan on a Zymark robotic system

Neels, O.; Jager, P.; Koopmans, K.; Eriks, E.; de Vries, E.; Kema, I.; Elsinga, P.

Precise staging of neuroendocrine tumors (NET) using positron emission tomography (PET) tracers visualizing their specific metabolic activity is of interest. Besides [18F]FDOPA, staging NET with carbon-11 labeled 5-hydroxytryptophan (5-HTP) is reported in recent literature. We implemented the multi-enzymatic synthesis of enantiomerically pure [11C]-L-5-HTP on a Zymark robotic system to compare both tracers in patient studies. [11C]-5-HTP can be synthesized in up to 24% radiochemical yields (EOB). Average specific activity is 44 000GBq/mmol in ca. 50 min from [11C]methyl iodide in radiochemical purities >99 %. The synthesis of 5-HTP is difficult due to its multi-enzymatic reaction steps but typical yields can be achieved of ca. 400 MBq. [11C]-5-HTP is now reliably used in ongoing studies for staging NET.

Keywords: [11C]-5-HTP; neuroendocrine tumors; robot; carbon-11; enzyme

  • Journal of Labelled Compounds and Radiopharmaceuticals 49(2006)10, 889-895
    DOI: 10.1002/jlcr.1110

Permalink: https://www.hzdr.de/publications/Publ-30982
Publ.-Id: 30982


Novel Preclinical and Radiopharmaceutical Aspects of [68Ga]Ga-PSMA-HBED-CC: A New PET Tracer for Imaging of Prostate Cancer

Eder, M.; Neels, O.; Müller, M.; Bauder-Wüst, U.; Remde, Y.; Schäfer, M.; Hennrich, U.; Eisenhut, M.; Afshar-Oromieh, A.; Haberkorn, U.; Kopka, K.

The detection of prostate cancer lesions by PET imaging of the prostate-specific membrane antigen (PSMA) has gained highest clinical impact during the last years. 68Ga-labelled Glu-urea-Lys(Ahx)-HBED-CC ([68Ga]Ga-PSMA-HBED-CC) represents a
successful novel PSMA inhibitor radiotracer which has recently demonstrated its suitability in individual first-in-man studies. The radiometal chelator HBED-CC used in this molecule represents a rather rarely used acyclic complexing agent with chemical characteristics favourably influencing the biological functionality of the PSMA inhibitor. The simple replacement of HBED-CC by the prominent radiometal chelator DOTA was shown to dramatically reduce the in vivo imaging quality of the respective 68Ga-labelled PSMA-targeted tracer proving that HBED-CC contributes intrinsically to the PSMA binding of the Glu-urea-Lys(Ahx) pharmacophore. Owing to the obvious growing clinical impact, this work aims to reflect the properties of HBED-CC as acyclic radiometal chelator and presents novel preclinical data and relevant aspects of the radiopharmaceutical production process of [68Ga]Ga-PSMA-HBED-CC.

Keywords: 68Ga-PET imaging; PSMA; HBED-CC; prostate cancer; radiopharmaceutical production; good manufacturing practice; GMP

Permalink: https://www.hzdr.de/publications/Publ-30981
Publ.-Id: 30981


Radionuclides: medicinal products or rather starting materials?

Neels, O.; Patt, M.; Decristoforo, C.

The EU directive 2001/83 describes the community code for medicinal products for human use including radiopharmaceuticals. In its current definition, also radionuclide precursors, such as fluorine-18, need to hold a marketing authorization before being placed on the market. The potential of novel radiopharmaceuticals for nuclear medicine is, although encouraged by European legislation and its respective guidance documents, therefore hampered by the regulatory framework. An update of EU directive 2001/83 would be beneficial for the development of novel radiopharmaceuticals and a safe advance in nuclear medicine.

Permalink: https://www.hzdr.de/publications/Publ-30980
Publ.-Id: 30980


The Thermocapillary Effect on Gas Bubbles Growing on Electrodes of Different Sizes

Hossain, S. S.; Mutschke, G.; Bashkatov, A.; Eckert, K.

Recently, the strongly inhomogeneous current density occuring near a microelectrode was identified as driving a thermocapillary electrolyte flow near gas bubbles growing during electrolysis [Massing et.al. Electrochim. Acta 297, 929 (2019) ]. The present paper is investigating this effect in more detail under various operating conditions. Furthermore, by simplified modeling, the question is answered of whether this effect is also of importance at large planar electrodes. The direction of the thermocapillary force on the bubble is found to change from retarding to advancing the bubble release when the size of the electrode is increased. Conclusions are drawn on how the thermocapillary effect at planar electrodes depends on the electrode coverage and the bubble departure size, also considering industrially relevant values of the current density.

Keywords: hydrogen evolution; electrolysis; thermocapillarity; Marangoni force; microelectrode; macroelectrode

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Permalink: https://www.hzdr.de/publications/Publ-30979
Publ.-Id: 30979


Automated [18F]PSMA-1007 production by a single use cassette-type synthesizer for clinical examination

Naka, S.; Watabe, T.; Kurimoto, K.; Uemura, M.; Soeda, F.; Neels, O.; Kopka, K.; Tatsumi, M.; Kato, H.; Nonomura, N.; Shimosegawa, E.; Cardinale, J.; Giesel, F.; Hatazawa, J.

Background: [18F]PSMA-1007, a positron emission tomography (PET) tracer, specifically targets prostate-specific membrane antigen (PSMA), which is highly expressed in prostate cancer. PSMA-PET is effective especially for regional detection of biochemical recurrence, which significantly affects patient management. Herein, we established and optimized a one-step radiolabeling protocol to separate and purify [18F]PSMA-1007 with a CFN-MPS200 synthesizer for clinical application.
Results: A dedicated single use cassette and synthesis program for [18F]PSMA-1007 was generated using a single-step method for direct precursor radiolabeling. In the cassette, three tube types (fluoro-elastomer, PharMed® BPT, silicone) and two different precursor salts (trifluoroacetic acid or acetic acid) were compared for optimization. Furthermore, three-lot tests were performed under optimized conditions for quality confirmation. Activity yields and mean radiochemical purity of [18F]PSMA-1007 were > 5000 MBq and 95%, respectively, at the end of synthesis, and the decay-corrected mean radiochemical yield from all three cassettes was approximately 40% using a trifluoroacetic acid salt precursor. Fluoro-elastomer tubings significantly increased the amount of non-radioactive PSMA-1007 (8.5 ± 3.1 μg/mL) compared to those with other tubings (0.3 μg/mL). This reduced the molar activity of [18F]PSMA-1007 synthesized in the cassette assembled by fluoro-elastomer tubings (46 GBq/μmol) compared to that with PharMed® BPT and silicone tubings (1184 and 1411 GBq/μmol, respectively). Residual tetrabutylammonium, acetonitrile, and dimethyl sulfoxide levels were <  2.6 μg/mL, < 8 ppm, and <  11 ppm, respectively, and ethanol content was 8.0–8.1% in all three cassettes and two different salts. Higher activity yields, radiochemical purities, and decay-corrected radiochemical yields were obtained using an acetic acid salt precursor rather than a trifluoroacetic acid salt precursor (7906 ± 1216 MBq, 97% ± 0%, and 56% ± 4%). In the three-lot tests under conditions optimized with silicone cassettes and acetic acid salt precursor, all quality items passed the specifications required for human use.
Conclusions: We successfully automated the production of [18F]PSMA-1007 for clinical use and optimized synthesis procedures with a CFN-MPS200 synthesizer using a silicone cassette and acetic acid salt precursor. Cassette availability will facilitate a wide spread use of [18F]PSMA-1007-PET, leading to an effective prostate cancer management.

Keywords: PET; PSMA; [18F]PSMA-1007; Cassette-type radiosynthesizer; SPE

Permalink: https://www.hzdr.de/publications/Publ-30978
Publ.-Id: 30978


Magnetic and magnetocaloric properties of Ni47Mn40Sn13−xZnx alloys: Direct measurements and first-principles calculations

Ghotbi Varzaneh, A.; Kameli, P.; Abdolhosseini Sarsani, I.; Ghorbani Zavareh, M.; Salazar Mejia, C.; Amiri, T.; Scurschii, I.; Luo, J. L.; Etsell, T. H.; Chernenko, V. A.

In the present study, the martensitic transformation (MT) and magnetic properties exhibited by the Ni-Mn-Sn Heusle-type magnetic shape memory alloys (MSMAs) doped with Zn have been investigated experimentally and theoretically. The inverse magnetocaloric effect (MCE) in Ni47Mn40Sn13−xZnx (x = 0, 1) was studied by direct measurements of the adiabatic temperature change, ΔTad, in pulsed magnetic fields of 5, 10, and 20 T. The Zn doping of the Ni-Mn-Sn alloy led to a striking enhancement of the value of ΔTad, e.g., from –2.5 for undoped to –11 K for Zn-doped alloys under a magnetic field amplitude of 20 T. The first-principles calculations were used to understand the origin of Zn-doping influence on MT, magnetic, and magnetocaloric properties. Particularly, the crystal structure and magnetic ordering influenced by the site occupancy in the undoped and Zn-doped alloys were analyzed. The results show that, whereas the usual transition metal elements with more valence electrons tend to enter the Ni sites, Zn atom prefers to occupy the Sn sublattice. The underlying physics of the drastic enhancement of MCE by Zn doping is discussed in terms of a partial disorder in the occupation sites of Zn atoms.

Permalink: https://www.hzdr.de/publications/Publ-30977
Publ.-Id: 30977


Direct imaging of the ac component of the pumped spin polarization with element specificity

Pile, S.; Buchner, M.; Ney, V.; Schaffers, T.; Lenz, K.; Narkovic, R.; Lindner, J.; Ohldag, H.; Ney, A.

Spin-pumping in a ferromagnet/non-ferromagnet heterostructure is directly imaged with spatial resolution as well as element selectivity. The time-resolved detection in scanning transmission x-ray microscopy allows to directly probe the spatial extent of the ac spin polarization in Co-doped ZnO which is generated by spin-pumping from an adjacent permalloy microstrip. Comparing the relative phases of the dynamic magnetization component of the two constituents is possible and found to be out of phase. The correlation between the distribution of the magnetic excitation in the permalloy and the Co-doped ZnO reveals that literally there is no one-to-one correlation. The observed distribution is rather complex, but integrating over larger areas clearly demonstrates that the spin polarization in the non-ferromagnet extends laterally beyond the region of the ferromagnetic microstrip. Therefore the observations are better explained by a local spin pumping efficieny and a lateral propagation of the ac spin-polarization in the non-ferromagnet over the range of a few micrometers.

Keywords: spin pumping; XMCD; ferromagnetic resonance; STXM; microstrip; spin waves

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Permalink: https://www.hzdr.de/publications/Publ-30976
Publ.-Id: 30976


Alkali metals inside bi-layer graphene and MoS2: insights from first-principles calculations

Chepkasov, I.; Ghorbani Asl, M.; Zakhar, I. P.; Jurgen, H. S.; Krasheninnikov, A.

Contrary to a wide-spread belief that alkali metal (AM) atoms intercalated into layered materials form single-layer structures only, recent experiments [Nature 564 (2018) 234] showed that multi-layer configurations of lithium are possible in bi-layer graphene. Using state-of-the-art first-principles calculations, we systematically study the intercalation energetics for various AMs (Li, Na, K, Rb, Cs) in bi-layer graphene and MoS2. We demonstrate that for bilayer graphene as host the formation energy of multilayer structures is negative for K, Rb and Cs and only slightly positive for both Li and Na. In view of the previous experimental data on lithium, a multilayer of Na might, therefore, form, while it is well-known that single-layers of Na in graphitic hosts are energetically very unfavorable. In MoS2, multi-layer structures are considerably higher in energy than the single-layer ones, but the formation of the former can still occur, especially for the AMs with the lowest electronegativity. To rationalize the results, we assess the charge transfer from the intercalants to the host material and analyze the interplay between the ionic and covalent bonding of AM and host atoms. While our theoretical effort primarily focuses on the fundamental aspects of AM intercalation, our findings may stimulate experimental work addressing multilayer intercalation to maximize the capacity of anode materials in AM ion batteries.

Keywords: Alkali metal-ion batteries; nanostructured materials; intercalation; first-principles simulations

Permalink: https://www.hzdr.de/publications/Publ-30971
Publ.-Id: 30971


Online Workshop: introduction to compositional data analysis

Tolosana Delgado, R.; Pospiech, S.

In this 2-day webinar we will see the problems arising with the conventional statistical analysis of compositional data, and present a general solution. We will learn how to generate and interpret compositional descriptive statistics; how to explore the inner structure of a data set with tools such as logratio principal component analysis; and we will fit predictive models to explain the variability in compositional data sets. These topics will be covered with a bit of theory, some examples from geochemistry and a few exercises in R, the open source environment for data analysis.

Keywords: PCA; alr; clr; regression; compositional data analysis; geochemistry

  • Open Access Logo Lecture (others) (Online presentation)
    Online Progress Meeting, Project NEXT, 11.-12.05.2020, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30968
Publ.-Id: 30968


In situ study of the synthesis of thorite (ThSiO4) under environmental representative conditions

Estevenon, P.; Causse, J.; Szenknect, S.; Welcomme, E.; Mesbah, A.; Moisy, P.; Poinssot, C.; Dacheux, N.

Thorite, ThSiO4 with Zircon structure type, is one of the most abundant natural source of thorium on earth. While actinides are known to form nanoparticles in silicate medium, no direct link between those colloids and crystalline form of thorite was evidenced until now. Here we show that thorite can be produced in experimental conditions close to environmental pH and temperature. Thanks to in-situ Small and Wide Angle X-rays Scattering (SWAXS) measurements, colloids of a few nanometers are first evidenced for low reaction time. These colloids exhibit elongated shapes and finally tend to aggregate after the size has reached 10 nm. Once aggregated, the system goes through a maturation step finishing with the emergence of nanocrystallites presenting thorite zircon structure. This maturation step is longer when the reaction temperature is decreased highlighting kinetic considerations. The conclusions of this article have potential implications in the paragenesis of Th minerals deposits, but also in the behaviour of Th and, by analogy, tetravalent actinides in the environment. The Th-silicate colloids evidenced in this work have, at low temperature and at near neutral pH, a long-term stability and a morphology in favor of a high mobility in groundwaters. If these species are formed in more diluted media, this could be problematic regarding to the spreading of Th and, by analogy of others tetravalent actinides in the environment.

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-30965
Publ.-Id: 30965


Enantiomerically pure Tetravalent Neptunium Amidinates: Synthesis and Characterization

Fichter, S.; Kaufmann, S.; Kaden, P.; Brunner, T. S.; Stumpf, T.; Roesky, P. W.; März, J.

The synthesis of a tetravalent neptunium amidinate [NpCl((S)-PEBA)₃] (1) ((S)-PEBA = (S,S)-N,N’-bis-(1-phenylethyl)-benzamidinate) is reported. This complex represents the first structurally characterized enantiopure transuranic compound. Reactivity studies with halide/pseudohalides yielding [NpX((S)-PEBA)₃] (X = F (2), Br (3), N3 (4)) have shown that the chirality-atmetal is preserved for all compounds in the solid state. Furthermore, they represent an unprecedented example of a structurally characterized metal-organic Np complex featuring a Np–Br (3) bond. In addition, 4 is the only reported tetravalent transuranic azide. All compounds were additionally characterized in solution using paramagnetic NMR spectroscopy showing an expected C₃ symmetry at low temperatures.

Keywords: transuranium chemistry; actinides; neptunium; coordination chemistry; amidinates

Related publications

Permalink: https://www.hzdr.de/publications/Publ-30964
Publ.-Id: 30964


Silicon nanowire sensorS for immunological treatment

Nguyen Le, T. A.; Sandoval Bojorquez, D. I.; Pérez Roig, A.; Bergoi, I.; Kihyun, K.; Gianaurelio, C.; Bachmann, M.; Baraban, L.

As of April 28, 2020, a pandemic called coronavirus disease 2019 (COVID-19) has spread to every continent of the world, infecting around three million people, and taken nearly 200,000 lives [1]. Although such deadly events are not new throughout human history, they often cause fear and uncertainty, mostly because of lacking information about the new strain of the virus. Insight about the virus and its working mechanism is perhaps important yet understanding the human immune response is the key to reducing mortality. Our immune system reacts differently depends on ages, genders, races, and health background. That explains dissimilar disease progression in patients where some develop critical conditions while others only have mild symptoms [2]. Accumulating evidences suggest patient with severe COVID-19 symptoms is due to cytokine - a common name for a broad spectrum of small proteins important in cell signalling, especially in the immune system - dysregulation [3-5]. Therefore, many studies have suggested a screening of cytokine profiles together with other immune cells responses for the determination of correct treatment [3,5]. Meanwhile, nanosensors such as silicon nanowire (SiNW) own advantages of being sensitive to small molecules, rapid and label-free [6]. In this poster, we demonstrate the use of a SiNW sensor in immunotherapy research, more specifically, in a system of switchable T-cell expressing chimeric antigen receptors (CARs). The sensor showed better sensitivity and a lower limit of detection compare to standard ELISA test. Moreover, thanks to its compatibility with CMOS technology which enables mass production, reproducibility is ensured [7]. Since the cytokine release syndrome (CRS) found in COVID-19 patients is also observed in patients receiving CAR-T therapy [4], the knowledge and tools generated by the SiNW sensor developed in this field of study may benefit the community. In the end, a full understanding and control of our immune system might be the key to fight any other pandemic in the future.

  • Open Access Logo Contribution to proceedings
    Biosensors for Pandemics: Reliable and efficient nanotech-based diagnostics in emergency situations 2020, 06.05.2020, Online, Online

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Permalink: https://www.hzdr.de/publications/Publ-30963
Publ.-Id: 30963


Light-Activated Carbon Monoxide Prodrugs Based on Bipyridyl Dicarbonyl Ruthenium(II) Complexes

Geri, S.; Krunclova, T.; Janouskova, O.; Panek, J.; Hruby, M.; Hernandez-Valdes, D.; Probst, B.; Alberto, R.; Mamat, C.; Kubeil, M.; Stephan, H.

Two photoactivatable dicarbonyl ruthenium(II) complexes based on an amide-functionalised bipyridine scaffold (4-position) equipped with an alkyne functionality or a green-fluorescent BODIPY (boron-dipyrromethene) dye have been prepared and used to investigate their light-induced decarbonylation. UV/Vis, FT-IR and 13C NMR spectroscopies as well as gas chromatography and multivariate curve resolution alternating least-squares analysis (MCR-ALS) were used to elucidate the mechanism of the decarbonylation process. Release of the first CO molecule occurs very quickly, while release of the second CO molecule proceeds more slowly. In vitro studies using two cell lines A431 (human squamous carcinoma) and HEK293 (human embryonic kidney cells) have been carried out in order characterise the anti-proliferative and anti-apoptotic activities. The BODIPY-labelled compound allows for monitoring the cellular uptake, showing fast internalisation kinetics and accumulation at the endoplasmic reticulum and mitochondria.

Keywords: ruthenium; photoCORMs; anti-proliferative; anti-apoptotic; fluorescent probes

Permalink: https://www.hzdr.de/publications/Publ-30962
Publ.-Id: 30962


Bionic Tracking: Using Eye Tracking to Track Biological Cells in Virtual Reality

Günther, U.; Harrington, K. I. S.; Dachselt, R.; Sbalzarini, I. F.

We present Bionic Tracking, a novel method for solving biological cell tracking problems with eye tracking in virtual reality using commodity hardware. Using gaze data, and especially smooth pursuit eye movements, we are able to track cells in time series of 3D volumetric datasets. The problem of tracking cells is ubiquitous in developmental biology, where large volumetric microscopy datasets are acquired on a daily basis, often comprising hundreds or thousands of time points that span hours or days. The image data, however, is only a means to an end, and scientists are often interested in the reconstruction of cell trajectories and cell lineage trees. Reliably tracking cells in crowded three-dimensional space over many timepoints remains an open problem, and many current approaches rely on tedious manual annotation and curation. In our Bionic Tracking approach, we substitute the usual 2D point-and-click annotation to track cells with eye tracking in a virtual reality headset, where users simply have to follow a cell with their eyes in 3D space in order to track it. We detail the interaction design of our approach and explain the graph-based algorithm used to connect different time points, also taking occlusion and user distraction into account. We demonstrate our cell tracking method using the example of two different biological datasets. Finally, we report on a user study with seven cell tracking experts, demonstrating the benefits of our approach over manual point-and-click tracking, with an estimated 2- to 10-fold speedup.

Keywords: virtual reality; eye tracking; cell tracking; visualization

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Permalink: https://www.hzdr.de/publications/Publ-30961
Publ.-Id: 30961


Adaptor CAR platforms - next generation of T cell-based cancer immunotherapy

Arndt, C.; Fasslrinner, F.; Rodrigues Loureiro, L. R.; Koristka, S.; Feldmann, A.; Bachmann, M.

The success of conventional chimeric antigen receptor (CAR) therapy in the treatment of refractory hematologic malignancies has triggered the development of novel exciting experimental CAR technologies. Among them, adaptor CAR platforms have received much attention. They combine the flexibility and controllability of recombinant antibodies with the power of CARs. Due to their modular design, adaptor CAR systems propose answers to central problems of conventional CAR therapy such as safety and antigen escape. This review provides an overview on the different adaptor CAR platforms available, discusses the possibilities and challenges of adaptor CAR therapy and summarizes first clinical experiences.

Keywords: chimeric antigen receptor (CAR); adaptor molecule; adoptive T cell therapy; cancer immunotherapy

Permalink: https://www.hzdr.de/publications/Publ-30960
Publ.-Id: 30960


A simulation-based exergetic analysis of NdFeB permanent magnet production to understand large systems

Belo Fernandes, I.; Abadias Llamas, A.; Reuter, M.

Metallurgical simulation and evaluation of the resource efficiency of whole production processes are of key importance for a sound environmental impact assessment. An exergy dissipation analysis is suitable for quantifying the theoretical limits for a process and pinpoint hotspots for improvement along the value chain. The production of NdFeB permanent magnets is evaluated through a simulation-based life cycle assessment and exergetic analysis, comprising 107 unit operations, 361 flows and 209 compounds. This methodology highlights areas with the greatest potential for improvements in terms of technology and environmental impact, shedding light on the true resource efficiency and minimum exergy dissipation for the production of permanent magnets, present in several low-carbon technologies. A maximum exergy efficiency of 60.7% shows that there is a limit for sustainability, which can be improved by technological improvements and recovery of waste streams, showing the inconvenient truth that the resource efficiency will never reach 100%.

Keywords: NdFeB magnet production; resource efficiency; exergetic life cycle assessment; process simulation; geometallurgy; large systems design

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-30959
Publ.-Id: 30959


Coupling of Lamb Waves and Spin Waves in Multiferroic Heterostructures

Tiwari, S.; Schneider, J. D.; Wintz, S.; Arekapudi, S. S. P. K.; Lenz, K.; Andres, C.; Lindner, J.; Hellwig, O.; Gregory, P. C.; Robert, N. C.

In this work, we investigate magneto-acoustic attenuation in thin film multiferroic Lamb wave delay lines. By leveraging magneto-acoustic interactions, multiferroics have potential to realize passive chip-scale alternatives to bulky ferrite devices. For the first time, magnetic field dependence of magnetoacoustic interactions in multiferroic Lamb wave devices is characterized. Multiferroic heterostructures of aluminum nitride and cobalt iron boron are fabricated into Lamb wave delay lines operating at 7.492 GHz to study the effect of strain nonuniformity on the multiferroic coupling. The attenuation of the Lamb waves is characterized as a function of the magnitude and angle of an applied in-plane bias magnetic field. It is found that the bias magnitude for peak attenuation is a strong function of angle, indicating that it is due to coupling between the Lamb waves and spin wave modes. This is in contrast with current models of attenuation in multiferroic SAW delay lines, where the uniform surface strains couple to ferromagnetic resonance, which has no angular dependence on the in-plane bias field magnitude. These results are the first steps towards passiv chip-scale alternatives to ferrite devices utilizing Lamb wave devices, which have better coupling and scalability than their SAW counterparts.

Keywords: Acoustic delay lines; Lamb waves; magnetoacoustics; MEMS; multiferroics; spin waves

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Permalink: https://www.hzdr.de/publications/Publ-30958
Publ.-Id: 30958


Direct Imaging of Distorted Vortex Structure and Vortex-Antivortex Mediated Vortex Annihilation In Exchange Coupled Ferromagnetic/Antiferromagnetic Disk Structures

Arekapudi, S. S. P. K.; Böhm, B.; Ramasubramanian, L.; Ganss, F.; Heinig, P.; Stienen, S.; Fowley, C.; Lenz, K.; Deac, A. M.; Albrecht, M.; Hellwig, O.

Topological spin textures such as skyrmions, merons, and vortices in antiferromagnetic (AFM)/ ferromagnetic (FM) materials are actively explored for utilization in future data storage and signal processing devices. An emergent half-integer spin texture such as a magnetic vortex can be stabilized in a soft magnetic NiFe disk structure. Due to the topological nature, the unwinding of the magnetic vortex phase is mediated by the dynamic creation and subsequent annihilation of magnetic singularities, such as Bloch points. This process enables the formation of intermediate topological phases such as vortex-antivortex (V-AV) pairs and edge states. Interfacial interactions between an AFM and a topologically non-trivial spin structure of a FM can stabilize and extend the lifetime of V-AV phases, which are typically considered intrinsic and dynamic are imaged using high-resolution in-field magnetic force microscopy. Additionally, these interactions are used to protect the emerged chirality in an otherwise degenerate chiral spin system, rather than to introduce a preferred chirality.

Keywords: Topological defects; Vortex-Antivortex pairs; Antiferromagnet/Ferromagnet; Chirality in magnetism; High resolution magnetic imaging; Magnetic Vortex

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Permalink: https://www.hzdr.de/publications/Publ-30955
Publ.-Id: 30955


Helium Ion Microscopy for Reduced Spin Orbit Torque Switching Currents

Dunne, P.; Fowley, C.; Hlawacek, G.; Kurian, J.; Atcheson, G.; Colis, S.; Teichert, N.; Kundys, B.; Venkatesan, M.; Lindner, J.; Deac, A. M.; Hermans, T.; Coey, J.; Doudin, B.

Spin orbit torque driven switching is a favourable way to manipulate nanoscale magnetic objects for both memory and wireless communication devices. The critical current required to switch from one stored magnetic state to another depends on the multilayer structure of the device and the intrinsic properties of the materials used, which are difficult to control on a local scale. Here we demonstrate how focused helium ion beam irradiation can be used to modulate the local magnetic anisotropy of a Co thin film at the microscopic scale. In-situ characterisation using the anomalous Hall effect showed up to an order of magnitude reduction of the magnetic anisotropy under irradiation in real-time, and using this, a multi-level storage element is demonstrated. The result is that current-driven spin-switching, with as little as 800 kA cm-2 can be achieved on predetermined areas of the film without the need for physical material patterning.

Keywords: spintronics; spin orbit torque switching; nanomagnetism; ion beam irradiation

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Permalink: https://www.hzdr.de/publications/Publ-30954
Publ.-Id: 30954


Structure of Reduced Cerium Oxide Ultrathin films on Pt(111): Local Atomic Environment and Long-range Order

Pelli Cresi, J.; Znaiguia, R.; Carlà, F.; Isern, H.; Benedetti, F.; Gasperi, G.; Amidani, L.; Valeri, S.; Boscherini, F.; Luches, P.

In order to optimize the catalytic functionality of cerium oxide it is important to understand the structural modifications associated with reduction of the material and the role of the proximity of metals, which are often coupled with the oxide in the applications. For this purpose, the evolution of the short- and long-range structure of cerium oxide ultrathin epitaxial films and nanostructures supported on Pt(111) is investigated using x-ray absorption spectroscopy at the Ce L3 edge and surface x-ray diffraction, during reduction by thermal treatments in vacuum. In epitaxial nanoislands, the reduction is associated with a contraction of the Ce-O distance and with the appearance of Ce-Pt bonds. The formation of a phase with a (2×2) periodicity after a thermal treatment at 1023 K is ascribed to the formation of a Pt5Ce alloy. Films of 3 nm thickness do not show, on average, significant structural modifications with the same thermal treatment, consistent with the hypothesis that the reduction involves only the topmost surface layers and it does not influence significantly the bulk structure of the material. This study demonstrates a strong interaction between cerium oxide and platinum, which has implications for the reactivity and stability of catalysts based on metals combined with reducible oxides.

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-30953
Publ.-Id: 30953


Logarithmic Elastic Response in the Dilute non-Kramers System Y1-xPrxIr2Zn20

Yanagisawa, T.; Hidaka, H.; Amitsuka, H.; Zherlitsyn, S.; Wosnitza, J.; Yamane, Y.; Onimaru, T.

Ultrasonic investigations of the single-site quadrupolar Kondo effect in diluted Pr system Y0.966Pr0.034Ir2Zn20 are reported. The elastic constant (C11C12)/2 is measured down to ~40 mK using ultrasound for the dilute system Y0.966Pr0.034Ir2Zn20 and the pure compound Yir2Zn20. We found that the elastic constant (C11C12)/2 of the Pr-dilute system exhibits a logarithmic temperature dependence below T0 ∼ 0.3 K, where non-Fermi-liquid (NFL) behavior in the specific heat and electrical resistivity is observed. This logarithmic temperature variation manifested in the Γ3-symmetry quadrupolar susceptibility is consistent with the theoretical prediction of the quadrupolar Kondo effect by D. L. Cox [1]. On the other hand, the pure compound Yir2Zn20 without 4f-electron contributions shows nearly no change in its elastic constants evidencing negligible phonon contributions. In addition, clear acoustic de Haas-van Alphen (dHvA) oscillations in the elastic constant were detected for both compounds on applying magnetic field. This is mainly interpreted as contribution from the Fermi surface of Yir2Zn20.

Permalink: https://www.hzdr.de/publications/Publ-30951
Publ.-Id: 30951


Observation of giant spin-split Fermi-arc with maximal Chern number in the chiral topological semimetal PtGa

Yao, M.; Manna, K.; Yang, Q.; Fedorov, A.; Voroshnin, V.; Schwarze, B. V.; Hornung, J.; Chattopadhyay, S.; Sun, Z.; Guin, S. N.; Wosnitza, J.; Borrmann, H.; Shekhar, C.; Kumar, N.; Fink, J.; Sun, Y.; Felser, C.

Non-symmorphic chiral topological crystals host exotic multifold fermions, and their associated Fermi arcs helically wrap around and expand throughout the Brillouin zone between the high-symmetry center and surface-corner momenta. However, Fermi-arc splitting and realization of the theoretically proposed maximal Chern number rely heavily on the spin-orbit coupling (SOC) strength. In the present work, we investigate the topological states of a new chiral crystal, PtGa, which has the strongest SOC among all chiral crystals reported to date. With a comprehensive investigation using high-resolution angle-resolved photoemission spectroscopy, quantum-oscillation measurements, and state-of-the-art ab initio calculations, we report a giant SOC-induced splitting of both Fermi arcs and bulk states. Consequently, this study experimentally confirms the realization of a maximal Chern number equal to ±4 in multifold fermionic systems, thereby providing a platform to observe large-quantized photogalvanic currents in optical experiments.

Permalink: https://www.hzdr.de/publications/Publ-30950
Publ.-Id: 30950


Quadrupolar susceptibility and magnetic phase diagram of PrNi2Cd20 with non-Kramers doublet ground state

Yanagisawa, T.; Hidaka, H.; Amitsuka, H.; Nakamura, S.; Awaji, S.; Green, E. L.; Zherlitsyn, S.; Wosnitza, J.; Yazici, D.; White, B. D.; Maple, M. B.

In this study, ultrasonic measurements were performed on a single crystal of cubic PrNi2Cd20, down to a temperature of 0.02 K, to investigate the crystalline electric field ground state and search for possible phase transitions at low temperatures. The elastic constant (C11−C12)/2, which is related to the Γ3-symmetry quadrupolar response, exhibits the Curie-type softening at temperatures below ∼30 K, which indicates that the present system has a Γ3 non-Kramers doublet ground state. A leveling-off of the elastic response appears below ∼0.1 K toward the lowest temperatures, which implies the presence of level splitting owing to a long-range order in a finite-volume fraction associated with Γ3-symmetry multipoles. A magnetic field–temperature phase diagram of the present compound is constructed up to 28 T for H || [110]. A clear acoustic de Haas–van Alphen signal and a possible magnetic-field-induced phase transition at H ∼26 T are also detected by high-magnetic-field measurements.

Permalink: https://www.hzdr.de/publications/Publ-30949
Publ.-Id: 30949


Sub-lattice of Jahn-Teller centers in hexaferrite crystal

Gudkov, V. V.; Sarychev, M. N.; Zherlitsyn, S.; Zhevstovskikh, I. V.; Averkiev, N. S.; Vinnik, D. A.; Gudkova, S. A.; Niewa, R.; Dressel, M.; Alyabyeva, L. N.; Gorshunov, B. P.; Bersuker, I. B.

A novel type of sub-lattice of the Jahn-Teller (JT) centers was arranged in Ti-doped barium hexaferrite BaFe12O19. In the un-doped crystal all iron ions, sitting in five different crystallographic positions, are Fe3+ in the high-spin configuration (S = 5/2) and have a non-degenerate ground state. We show that the electron-donor Ti substitution converts the ions to Fe2+ predominantly in tetrahedral coordination, resulting in doubly-degenerate states subject to the E ⊗ e problem of the JT effect. The arranged JT complexes, Fe2+O4, their adiabatic potential energy, non-linear and quantum dynamics, have been studied by means of ultrasound and terahertz-infrared spectroscopies. The JT complexes are sensitive to external stress and applied magnetic field. For that reason, the properties of the doped crystal can be controlled by the amount and state of the JT complexes.

Permalink: https://www.hzdr.de/publications/Publ-30948
Publ.-Id: 30948


Synthesis and crystal structures of transition metal(II) fluoridometallate(IV) hydrates of neptunium and plutonium: AIIMIVF₆∙3H₂O (AII = Mn, Zn; MIV = Np, Pu)

Scheibe, B.; März, J.; Schmidt, M.; Stumpf, T.; Kraus, F.

Transition metal(II) fluoridometallates(IV) AIIMIVF6∙3H2O (AII = Mn, Zn; MIV = Np, Pu) were synthesized from NpO2 or PuO2 and the respective transition metal chlorides from hydrofluoric acid under mild conditions. The olive-green (Np) or orange (Pu) compounds were obtained as single-crystals and the respective structures were determined by single-crystal X-ray diffraction. In the isotypic compounds, chains of edgesharing tricapped trigonal prismatic polyhedra, [MIVF8/2(H2O)1/1] ∞1, are present and an overall threedimensional network structure is observed in which the AII and MIV atoms are arranged according to the simple NaCl structure type. Within the respective U-Pu series of the Zn and Mn salts the cell volumes and the MIV−F distances decrease due to the actinoid contraction.

Keywords: actinoid; neptunium; plutonium; fluoride; single-crystal X-ray diffraction

Permalink: https://www.hzdr.de/publications/Publ-30947
Publ.-Id: 30947


Experimentelle Untersuchung der Zweiphasenströmung im Rührkessel

Rox, H.

Die Kenntnis des Strömungsfeldes einer Zweiphasenströmung (fest/flüssig) in Rührkesseln, insbesondere hinsichtlich der Turbulenz, stellt einen Schwerpunkt für das Verständnis des industriell relevanten Flotationsprozesses sowie dessen numerischen Simulation dar. In dieser Arbeit werden die Strömungsfelder der Fluidphase (deionisiertes Wasser) und Feststoffphase (Polyethylen- bzw. Glaspartikel mit d_P = 63...70 μm; d_P = 150...180 μm; d_P = 425...500 μm) mithilfe von Particle Image Velocimetry und Particle Shadow Velocimetry ermittelt sowie mit Ergebnissen aus der Literatur und numerischen Simulationen verglichen. Es wird der Einfluss der Feststoffpartikel auf das Geschwindigkeitsfeld, die turbulenten Schwankungsgeschwindigkeiten sowie die Verteilung der Partikel im Rührkessel (D_K = 90 mm) betrachtet. Hierfür wird die Volumenkonzentration der Partikel in drei Schritten von 0,025 vol-% auf 0,1 vol-% erhöht und die Partikel werden mittels Scheibenrührer (Re_R = 9,7; 14,9 oder 22,4*10⁴) suspendiert. Entscheidend für den Einfluss der Partikel auf die Flüssigphase sind der Partikeldurchmesser und die Partikeldichte. Bei den betrachteten Volumenkonzentrationen scheint diese vernachlässigbar zu sein. Innerhalb des Rührerstrahls wird in Lauflänge eine zunehmende Dämpfung der radialen Geschwindigkeit sowie teilweise eine leichte Ablenkung des Rührerstrahls Richtung Rührkesselboden festgestellt. Bei den axialen Geschwindigkeiten dominieren Partikel großer Stokes-Zahlen die abwärtsgerichtete Zweiphasenströmung und können dem Fluid nicht folgen. Die turbulenten Schwankungsgeschwindigkeiten werden generell durch die Partikel (Re_P < 170) gedämpft. Es wird bestätigt, dass die konkrete Rührerstellung keinen Einfluss auf das Strömungsfeld im äußeren Bereich des Rührkessels besitzt.

Keywords: Zweiphasenströmung; Rührkessel; Particle Image Velocimetry; PIV; Particle Shadow Velocimetry; PSV; Turbulenz; Feststoffpartikel; Flotation

  • Diploma thesis
    TU Dresden, 2020
    Mentor: Prof. Dr. et Ing. habil. Kerstin Eckert
    161 Seiten

Permalink: https://www.hzdr.de/publications/Publ-30946
Publ.-Id: 30946


Surface Modification of Silicon Nanowire Based Field Effect Transistors with Stimuli Responsive Polymer Brushes for Biosensing Applications

Klinghammer, S.; Rauch, S.; Pregl, S.; Uhlmann, P.; Baraban, L.; Cuniberti, G.

We demonstrate the functionalization of silicon nanowire based field effect transistors (SiNW FETs) FETs with stimuli-responsive polymer brushes of poly(N-isopropylacrylamide) (PNIPAAM) and poly(acrylic acid) (PAA). Surface functionalization was confirmed by atomic force microscopy, contact angle measurements, and verified electrically using a silicon nanowire based field effect transistor sensor device. For thermo-responsive PNIPAAM, the physicochemical properties (i.e., a reversible phase transition, wettability) were induced by crossing the lower critical solution temperature (LCST) of about 32 °C. Taking advantage of this property, osteosarcomic SaoS-2 cells were cultured on PNIPAAM-modified sensors at temperatures above the LCST, and completely detached by simply cooling. Next, the weak polyelectrolyte PAA, that is sensitive towards alteration of pH and ionic strength, was used to cover the silicon nanowire based device. Here, the increase of pH will cause deprotonation of the present carboxylic (COOH) groups along the chains into negatively charged COO− moieties that repel each other and cause swelling of the polymer. Our experimental results suggest that this functionalization enhances the pH sensitivity of the SiNW FETs. Specific receptor (bio-)molecules can be added to the polymer brushes by simple click chemistry so that functionality of the brush layer can be tuned optionally. We demonstrate at the proof-of concept-level that osteosarcomic Saos-2 cells can adhere to PNIPAAM-modified FETs, and cell signals could be recorded electrically. This study presents an applicable route for the modification of highly sensitive, versatile FETs that can be applied for detection of a variety of biological analytes.

Keywords: Si NW sensors; polymer brushes

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Permalink: https://www.hzdr.de/publications/Publ-30945
Publ.-Id: 30945


Two‐Dimensional Boronate Ester Covalent Organic Framework Thin Films with Large Single Crystalline Domains for Neuromorphic Memory Device

Park, S.; Liao, Z.; Ibarlucea, B.; Qi, H.; Lin, H.-H.; Becker, D.; Melidonie, J.; Zhang, T.; Sahabudeen, H.; Baraban, L.; Baek, C.-K.; Zheng, Z.; Zschech, E.; Fery, A.; Heine, T.; Kaiser, U.; Cuniberti, G.; Dong, R.; Feng, X.

Despite the recent progress in the synthesis of crystalline boronate ester covalent organic frameworks (BECOFs) in powder and thin‐film through solvothermal method and on‐solid‐surface synthesis, respectively, their applications in electronics, remain less explored due to the challenges in thin‐film processability and device integration associated with the control of film thickness, layer orientation, stability and crystallinity. Moreover, although the crystalline domain sizes of the powder samples can reach micrometer scale (up to ≈1.5 μm), the reported thin‐film samples have so far rather small crystalline domains up to 100 nm. Here we demonstrate a general and efficient synthesis of crystalline two‐dimensional (2D) BECOF films composed of porphyrin macrocycles and phenyl or naphthyl linkers (named as 2D BECOF‐PP or 2D BECOF‐PN) by employing a surfactant‐monolayer‐assisted interfacial synthesis (SMAIS) on the water surface. The achieved 2D BECOF‐PP is featured as free‐standing thin film with large single‐crystalline domains up to ≈60 μm2 and tunable thickness from 6 to 16 nm. A hybrid memory device composed of 2D BECOF‐PP film on silicon nanowire‐based field‐effect transistor is demonstrated as a bio‐inspired system to mimic neuronal synapses, displaying a learning–erasing–forgetting memory process.

Keywords: neuromorphic computing; emulation of synaptic plasticity; 2D materials

Permalink: https://www.hzdr.de/publications/Publ-30944
Publ.-Id: 30944


Anisotropic exclusion effect between photocatalytic Ag/AgCl Janus particles and passive beads in a dense colloidal matrix

Huang, T.; Gobeil, S.; Wang, X.; Misko, V.; Nori, F.; de Malsche, W.; Faßbender, J.; Makarov, D.; Cuniberti, G.; Baraban, L.

Synthetic nano- and micromotors interact with each other and their surroundings in a complex manner. Here, we report on the anisotropy of active-passive particle interaction in a soft matter system containing an immobile yet photochemical Ag/AgCl-based Janus particle embedded in a dense matrix of passive beads in pure water. The asymmetry in the chemical gradient around the Janus particle, triggered upon visible light illumination, distorts the isotropy of the surrounding electric potential and results in the repulsion of adjacent passive beads to a certain distance away from the Janus particle. This exclusion effect is found to be anisotropic with larger distances to passive beads in front of the Ag/AgCl cap of the Janus particle. We provide insight into this phenomenon by performing the angular analysis of the radii of exclusion and tracking their time evolution at the level of a single bead. Our study provides a novel fundamental insight into the collective behavior of a complex mixture of active and passive particles and is relevant for various application scenarios, e.g., particle transport at micro- and nanoscale and local chemical sensing.

Keywords: photocatalytic reaction; micro and nanomotors; visible light; active Janus particles; spherical colloidal particles; exclusion phenomena

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Permalink: https://www.hzdr.de/publications/Publ-30943
Publ.-Id: 30943


Interaction of cyanobacteria with calcium facilitates the sedimentation of microplastics in a eutrophic reservoir

Leiser, R.; Jongsma, R.; Bakenhus, I.; Möckel, R.; Philipp, B.; Neu, T.; Wendt-Potthoff, K.

Low-density microplastics are frequently found in sediments of many lakes and reservoirs. The processes leading to sedimentation of initially buoyant polymers are poorly understood for inland waters. This study investigated the impact of biofilm formation and aggregation on the density of buoyant polyethylene microplastics. Biofilm formation on polyethylene films (4 × 4 × 0.15 mm) was studied in a eutrophic reservoir (Bautzen, Saxony, Germany). Additionally, aggregation dynamics of small PE microplastics (∼85 µm) with cyanobacteria were investigated in laboratory experiments. During summer phototrophic sessile cyanobacteria (Chamaesiphon spp. and Leptolyngbya spp.) precipitated calcite while forming biofilms on microplastics incubated in Bautzen reservoir. Subsequently the density of the biofilms led to sinking of roughly 10 % of the polyethylene particles within 29 days of incubation. In the laboratory experiments planktonic cyanobacteria (Microcystis spp.) formed large and dense cell aggregates under the influence of elevated Ca2+ concentrations. These aggregates enclosed microplastic particles and led to sinking of a small portion (∼0.4 %) of polyethylene microplastics. This study showed that both sessile and planktonic phototrophic microorganisms mediate processes influenced by calcium which facilitates densification and sinking of microplastics in freshwater reservoirs. Loss of buoyancy leads to particle sedimentation and could be a prerequisite for the permanent burial of microplastics within reservoir sediments.

Keywords: Microplastics; Reservoirs; Cyanobacteria; Calcite; Biofouling; Biofilms; Sedimentation

Permalink: https://www.hzdr.de/publications/Publ-30941
Publ.-Id: 30941


High-field quantum disordered state in α−RuCl3: Spin flips, bound states, and multiparticle continuum

Sahasrabudhe, A.; Kaib, D. A. S.; Reschke, S.; German, R.; Koethe, T. C.; Buhot, J.; Kamenskyi, D.; Hickey, C.; Becker, P.; Tsurkan, V.; Loidl, A.; Do, S. H.; Choi, K. Y.; Grüninger, M.; Winter, S. M.; Wang, Z.; Valentí, R.; van Loosdrecht, P. H. M.

Layered α−RuCl3 has been discussed as a proximate Kitaev spin-liquid compound. Raman and terahertz spectroscopy of magnetic excitations confirms that the low-temperature antiferromagnetic ordered phase features a broad Raman continuum, together with two magnonlike excitations at 2.7 and 3.6 meV, respectively. The continuum strength is maximized as long-range order is suppressed by an external magnetic field. The state above the field-induced quantum phase transition around 7.5 T is characterized by a gapped multiparticle continuum out of which a two-particle bound state emerges, together with a well-defined single-particle excitation at lower energy. Exact diagonalization calculations demonstrate that Kitaev and off-diagonal exchange terms in the Fleury-Loudon operator give rise to a pronounced intensity of these features in the Raman spectra. Our Rapid Communication firmly establishes the partially polarized quantum disordered character of the high-field phase.

Permalink: https://www.hzdr.de/publications/Publ-30940
Publ.-Id: 30940


Increased static dielectric constant in ZnMnO and ZnCoO thin films with bound magnetic polarons

Vegesna, S. V.; Bath, V. J.; Bürger, D.; Dellith, J.; Skorupa, I.; Schmidt, O. G.; Schmidt, H.

A novel small signal equivalent circuit model is proposed in the inversion regime of metal/(ZnO, ZnMnO, and ZnCoO) semiconductor/Si3N4 insulator/p-Si semiconductor (MSIS) structures to describe the distinctive nonlinear frequency dependent capacitance (C-F) and conductance (G-F) behaviour in the frequency range from 50 Hz to 1 MHz. We modelled the fully depleted ZnO thin films to extract the static dielectric constant (εr) of ZnO, ZnMnO, and ZnCoO. The extracted enhancement of static dielectric constant in magnetic n-type conducting ZnCoO (εr ≥ 13.0) and ZnMnO (εr ≥ 25.8) in comparison to unmagnetic ZnO (εr = 8.3–9.3) is related to the electrical polarizability of donor-type bound magnetic polarons (BMP) in the several hundred GHz range (120 GHz for CdMnTe). The formation of donor-BMP is enabled in n-type conducting, magnetic ZnO by the s-d exchange interaction between the electron spin of positively charged oxygen vacancies Vo + in the BMP center and the electron spins of substitutional Mn2+ and Co2+ ions in ZnMnO and ZnCoO, respectively. The BMP radius scales with the Bohr radius which is proportional to the static dielectric constant. Here we show how BMP overlap can be realized in magnetic n-ZnO by increasing its static dielectric constant and guide researchers in the field of transparent spintronics towards ferromagnetism in magnetic, n-ZnO.

Permalink: https://www.hzdr.de/publications/Publ-30939
Publ.-Id: 30939


Controls on strath terrace formation and evolution: The lower Guadiana River, Pulo do Lobo, Portugal

Ortega-Becerril, J. A.; Garzón, G.; Tejero, R.; Meriaux, A.-S.; Delunel, R.; Merchel, S.; Rugel, G.

The lower Guadiana River carves a wide canyon in the Variscan metamorphic rocks of the SW Iberian Peninsula and presents an exceptionally homogeneous and well-preserved case of a strath terrace (ST) some 40 km long and 400 m wide. The rocky surface or strath shows different characteristics and development stages. Upstream, the lateral erosion level forms a flooded riverbed, or submerged strath, that gradually rises above the thalweg and develops into an active floodplain. Downstream, below the 15 m high Pulo do Lobo waterfall, the strath is incised by an inner canyon that forms a terrace on both sides. The inner channel increasingly widens and the ST loses its longitudinal continuity, yet remains prone to flooding during extraordinary magnitude floods. To assess the factors controlling the formation of this ST, we examined the roles of key drivers of ST formation: lithological hardness, tectonic structures and climate change, using cosmogenic data to create a chronologic context. The ST developed favoured by a monotonous succession of phyllites, as shown by Schmidt hammer resistance data, and interbedded more resistant quartz veins do not significantly alter its flat configuration. Variscan structures and measured joints determine the main orientation of the river and control the drainage network pattern. The intersection of the NS and NE-SW fractures promotes a wavy surface due to three-dimensional minor fold trains that act as discontinuities and play an important role in ST erosion through quarrying and plucking. However, we detected no evidence of ST deformation attributable to recent or Late Cenozoic tectonic activity.

The upstream active riverbed progressively changes downstream into an ST. This implies that Be radiometric ages obtained at Pulo do Lobo may not represent the ST's genetic age but rather the time of dismantling of its alluvial or sedimentary cover. This means the strath surface formed prior to its cosmogenic age and was therefore controlled by a higher base level, indicating a higher sea level than the current one, given the downstream area studied. The Quaternary sea level fluctuations show records of only a few meters above the current level. Instead, the sea level low stand maintains an average depth of −60 m, reaching −140 m during the last glacial period. This low base level context could justify the strong incision of the inner channel within the ST, but not the age of strath surface genesis and expansion and thus this surface should have evolved previously. The highest possible sea level stand corresponds to the Pliocene transgression, which reached an elevation of 120 m in the region, covering Miocene paleorelief. The mouth of the Guadiana River at that time resembled a fluvio-deltaic embayment between the Algarve domain and the Guadalquivir depression, which was infilled with fluvial deposits at the end of the transgression. Collectively, these data suggest that cosmogenic dating would define the time of exhumation of this Pliocene sedimentary cover.

Despite great variation of the ST ages, estimated incision rates at the knickpoint area are consistent with the total entrenchment of the Pulo do Lobo fall, especially if we consider that data correspond to an active erosion site. Highest erosion rates were found for the pothole area compared to those obtained for the higher ST surface. Radiometric ages correspond to the period of lowest Quaternary sea level and during which headward erosion would have been very active in the inner channel. The waterfall area shows more resistant lithology in its concentrated quartz veins, but this effect is inconspicuous at the ST surface. The regular gradient of 0.02 m/m and vast extension of this perched strath, linked upstream to the Guadiana riverbed, indicates a relic exhumed surface beneath its sedimentary cover. Notwithstanding the subsiding activity of the Gulf of Cádiz, the continental margin behaves as a tectonically stable block, which allows for the persistence of former morphologies in these ancient landscapes reshaped by bedrock river dissection.

Keywords: Strath terrace; Knickpoint; Inner channel; Bedrock rivers; Guadiana canyon

Permalink: https://www.hzdr.de/publications/Publ-30938
Publ.-Id: 30938


Hybrid graphene-based material promising target in laser matter interaction

Cutroneo, M.; Torrisi, L.; Badziak, J.; Rosinski, M.; Torrisi, A.; Fazio, M.; Sofer, Z. E.; Böttger, R.; Akhmadaliev, S.

Graphene oxide foils implanted with copper ions at low energy and high dose, have been proposed as hybrid graphene-based materials suitable to be laser irradiated in vacuum to produce hot plasmas. The special lattice structure of the graphene oxide foil can improve the propagation of the laser accelerated electrons inside the foil and to enhance the electron density emerging from the rear foil surface. In such conditions the electric field developed in the non-equilibrium plasma increases and consequently in the forward ion acceleration. The foils have been optimized in thickness and they were irradiated with optimized laser parameters in order to produce high energy and quasi-monoenergetic proton beams by the femtosecond laser at the Institute of Plasma Physics and Laser Microfusion in Warsaw, Poland. Gaf chromic film and silicon carbide detectors were used to monitor the plasma properties and to measure the velocity of the emitted protons and carbon ions from plasma.

Keywords: Data analysis; Lasers

Permalink: https://www.hzdr.de/publications/Publ-30937
Publ.-Id: 30937


Radiation damage tolerance of a novel metastable refractory high entropy alloy V2.5Cr1.2WMoCo0.04

Patel, D.; Richardson, M. D.; Jim, B.; Akhmadaliev, Sh.; Goodall, R.; Gandy, A. S.

A novel multicomponent alloy, V2.5Cr1.2WMoCo0.04, produced from elements expected to favour a BCC crystal structure, and to be suitable for high temperature environments, was fabricated by arc melting and found to exhibit a multiphase dendritic microstructure with W-rich dendrites and V-Cr segregated to the inter-dendritic cores. The as-cast alloy displayed an apparent single-phase XRD pattern. Following heat treatment at 1187 °C for 500 h the alloy transformed into three different distinct phases - BCC, orthorhombic, and tetragonal in crystal structure. This attests to the BCC crystal structure observed in the as-cast state being metastable. The radiation damage response was investigated through room temperature 5 MeV Au+ ion irradiation studies. Metastable as-cast V2.5Cr1.2WMoCo0.04 shows good resistance to radiation induced damage up to 40 displacements per atom (dpa). 96 wt% of the as-cast single-phase BCC crystal structure remained intact, as exhibited by grazing incidence X-ray diffraction (GI-XRD) patterns, whilst the remainder of the alloy transformed into an additional BCC crystal structure with a similar lattice parameter. The exceptional phase stability seen here is attributed to a combination of self-healing processes and the BCC structure, rather than a high configurational entropy, as has been suggested for some of these multicomponent "High Entropy Alloy" types. The importance of the stability of metastable high entropy alloy phases for behaviour under irradiation is for the first time highlighted and the findings thus challenge the current understanding of phase stability after irradiation of systems like the HEAs.

Keywords: High entropy alloy (HEA); Structural materials; Ion implantation; Radiation damage; Metastability

Permalink: https://www.hzdr.de/publications/Publ-30936
Publ.-Id: 30936


Diamond-blade diced trapezoidal ridge waveguides in YCOB crystal for second harmonic generation

Chen, C.; Lu, Q.; Akhmadaliev, S.; Zhou, S.

Trapezoidal ridge waveguides have been fabricated in YCOB nonlinear optical crystals by carbon ion irradiation and precise diamond-blade dicing. The diced ridges with smooth side-walls allow for near-infrared (1064 nm) light guiding with propagation losses around 1 dB/cm. Refractive index profile of a waveguide has been reconstructed in a reasonable manner. Green second harmonic light have been generated at room temperature via type I birefringent phase matching. Under the pump of continuous and pulsed lasers, conversion efficiencies for guided-wave frequency doubling can be up to ~1.10% Wsup-1 and ~6.22%, respectively.

Keywords: Trapezoidal ridge waveguides; YCOB crystal; SHG

Permalink: https://www.hzdr.de/publications/Publ-30935
Publ.-Id: 30935


Validation of AIAD sub-models for advanced numerical modelling of horizontal two-phase flows

Höhne, T.; Porombka, P.; Moya Saez, S.

In this work the modelling of horizontal two-phase flows within the two-fluid Euler-Euler approach is investigated. A modified formulation of the morphology detection functions within the Algebraic Interfacial Area Density (AIAD) model is presented in combination with different models for the drag force acting on a sheared gas-liquid interface. In case of free surface flows, those closure laws are often based on experimental correlations whose applicability is limited to certain flow regimes. It is investigated here whether the implementation of the modified blending functions in ANSYS CFX avoids this limitation. The influence of the new functions on the prediction of turbulence parameters in free surface flows is also examined quantitatively for the k-ω and k-ε two-equations turbulence models. Transient simulations of the WENKA counter-current stratified two-phase flow experiment were performed for validation. Predict of the correct flow pattern as observed in the experiment improved dramatically when a turbulence damping term was included in the standard two-equation models. Using the k-ω and a modified k-ε turbulence model with damping terms close to the interface, better agreement with the experimental data was achieved. The morphology detection mechanism of the unified blending functions within the AIAD is seen as an improvement with respect to the detection of sharp interfaces. Satisfactory quantitative agreement is achieved for the modified free surface drag. Furthermore, it is demonstrated that turbulence dampening has to be accounted for both turbulence models to qualitatively reproduce the mean flow and turbulence quantities from the experiment.

Keywords: Two-phase flow; CFD; AIAD; Horizontal flow; Turbulence

Permalink: https://www.hzdr.de/publications/Publ-30932
Publ.-Id: 30932


Detailed Simulation of the Nominal Flow and Temperature Conditions in a Pre-Konvoi PWR Using Coupled CFD and Neutron Kinetics

Höhne, T.; Kliem, S.

Since 2005, events have occurred involving increased operational oxidation of M5 fuel rod claddings at several German pressurized water reactors (PWRs). The conspicuous corrosion was observed mainly in the area between the two uppermost spacer grids (SG), i.e. the 8th and the 9th SG. In this area the transition from the active fuel rod area (filled with fuel) to the fuel rod plenum takes place. In some cases, the increased oxide layer was even found in the region of the fuel rod plenum, where no appreciable power is transferred from the fuel rod to the coolant.

One of the hypotheses assumes that an initial oxide layer first arises more or less over the entire length of the fuel rod. Depending on the height position different thermal conditions may occur in the form of temperature fluctuations. According to this hypothesis, it is assumed that the oxide layer ruptures due to the load from alternating temperatures, creating pathways where oxidizing species reach the metallic cladding rod surface. As a result, the oxide layer loses its protective effect and thicker oxide layers can grow up. From earlier experimental investigations at ROCOM (Rossendorf Coolant Mixing Test Facility) it is known that strong, large-scale vortex structures are present in the upper plenum of the RPV.

The aim of the present study was the detection of possible vortices in the upper part of the core. Therefore, a numerical simulation of the flow conditions in a Pre-Konvoi Pressurized Water Reactor (PWR) was carried out based on a complex 3D CFD model. The geometry of the CFD model includes the entire Reactor Pressure Vessel (RPV) plus all relevant internals. The core is modelled as a porous body, the different pressure losses along and transverse to the main flow direction were considered. The spacer-grid levels were taken into account to the extent that in these areas no cross-flow is possible. The calculation was carried out for nominal operating conditions, i.e. for full load operation. Furthermore, a prototypical End of Cycle (EOC) power distribution was assumed. For this, a power distribution was applied as obtained from a stationary full-core calculation with the 3D neutron kinetics code DYN3D. In order to be able to adequately reproduce flow vortexes, the calculation was performed transiently with suitable Detached Eddy Simulations (DES) turbulence models.

The calculation showed fluctuating transverse flow in the upper part of the core, starting at the 8th spacer grid but also revealed that no large dominant vortices exists in this region. It seems that the core acts as a rectifier attenuating large-scale vortices. The analyses included several spacer grid levels in the core and showed that in some areas of the core cross-section an upward increasingly directed transversal flow to the outlet nozzle occurs. In other areas of the core cross-section, on the other hand, there is nearly any cross-flow. However, the following limitations of the model apply: In the model all fuel elements are treated identical and cross flows due to different axial pressure losses for different FA types cannot be displayed. The complex structure of the FAs (eg. flow vanes in spacer grids) could also influence the formation of large-scale vortices. This effect could only be resolved with a very high number of grid elements (several billions). This is currently not possible from a computational point of view. Also, the possible influence of two-phase flows was not considered.

Keywords: PWR; CFD; Neutron Kinetics; Turbulence

  • Contribution to proceedings
    CFD4NRS-8 : Computational Fluid Dynamics for Nuclear Reactor Safety - OECD/NEA Workshop, 25.-27.11.2020, Palaiseau, Frankreich
  • Lecture (Conference)
    CFD4NRS-8 : Computational Fluid Dynamics for Nuclear Reactor Safety - OECD/NEA Workshop, 25.-27.11.2020, Palaiseau, Frankreich
  • Open Access Logo Fluids 5(2020)3, 161
    Online First (2020) DOI: 10.3390/fluids5030161

Permalink: https://www.hzdr.de/publications/Publ-30930
Publ.-Id: 30930


Freeze–Thaw-Promoted Fabrication of Clean and Hierarchically Structured Noble-Metal Aerogels for Electrocatalysis and Photoelectrocatalysis

Du, R.; Joswig, J.-O.; Hübner, R.; Zhou, L.; Wei, W.; Hu, Y.; Eychmüller, A.

Noble-metal aerogels (NMAs) have drawn increasing attention because of their self-supported conductive networks, high surface areas, and numerous optically/catalytically active sites, enabling their impressive performance in diverse fields. However, the fabrication methods suffer from tedious procedures, long preparation times, unavoidable impurities, and uncontrolled multiscale structures, discouraging their developments. By utilizing the self-healing properties of noble-metal aggregates, the freezing-promoted salting-out behavior, and the ice-templating effect, a freeze-thaw method is crafted that is capable of preparing various hierarchically structured noble-metal gels within one day without extra additives. In light of their cleanliness, the multi-scale structures, and combined catalytic/optical properties, the electrocatalytic and photoelectrocatalytic performance of NMAs are demonstrated, which surpasses that of commercial noble-metal catalysts.

Keywords: electrochemistry; gels; nanostructures; photocatalysis; sol-gel process

Permalink: https://www.hzdr.de/publications/Publ-30929
Publ.-Id: 30929


Dose-escalated simultaneously integrated boost photon or proton therapy in pancreatic cancer in an in silico study: gastrointestinal organs remain critical

Stefanowicz, S.; Waldemar, W.; Susanne, F.; Sebastian, Z.; Troost, E. G. C.

Purpose
To compare the dosimetric results of an in silico study among intensity-modulated photon (IMRT) and robust multi-field optimized intensity-modulated proton (rMFO-IMPT) treatment techniques using a dose-escalated simultaneously integrated boost (SIB) approach in locally recurrent or locally advanced pancreatic cancer patients.

Material and Methods
For each of 15 locally advanced pancreatic cancer patients, a volumetric modulated arc therapy (VMAT), a Tomotherapy (TOMO), and an rMFO-IMPT treatment plan was optimized on free-breathing treatment planning computed tomography (CT) images. For the photon treatment plans, doses of 66Gy and 51Gy, both as SIB in 30 fractions, were prescribed to the gross tumor volume (GTV) and to the planning target volume (PTV), respectively. For the proton plans, a dose prescription of 66Gy(RBE) to the GTV and of 51Gy(RBE) to the clinical target volume (CTV) was planned. For each SIB-treatment plan, doses to the targets and OARs were evaluated and statistically compared.

Results
All treatment techniques reached the prescribed doses to the GTV and CTV or PTV. The stomach and the bowel, of the latter in particular the duodenum and the small bowel, were found to be frequently exposed to doses exceeding 50Gy, irrespective of the treatment technique. For doses below 50Gy, the IMPT technique was statistically significant superior to both IMRT techniques regarding decreasing dose to the OARs, e.g. volume of the bowel receiving 15Gy (V15Gy) was reduced for rMFO compared to VMAT (p=0.003) and TOMO (p<0.001).

Conclusion
With all photon and proton techniques investigated, the radiation dose to gastrointestinal OARs remained critical when treating patients with unresectable locally advanced or locally recurrent pancreatic cancer using a dose-escalated SIB approach.

Keywords: Pancreatic cancer; intensity-modulated radiation therapy; intensity-modulated proton therapy; robust optimization; simultaneously integrated boost; dose escalation

Permalink: https://www.hzdr.de/publications/Publ-30928
Publ.-Id: 30928


Magnetic transition due to the inter-singlet spin-exchange interaction and elastic softening by the interplay of electric quadrupoles in the distorted kagome lattice antiferromagnet Tb3Ru4Al12

Ishii, I.; Mizuno, T.; Kumano, S.; Umeno, T.; Suzuki, D.; Kurata, Y.; Suzuki, T.; Gorbunov, D.; Henriques, M. S.; Andreev, A. V.

The distorted kagome lattice antiferromagnet Tb3Ru4Al12 with a hexagonal structure has the Néel temperature TN = 22 K. To clarify the 4 f -electronic state and an influence of electric quadrupoles in Tb3Ru4Al12, ultrasonic measurements on a single-crystalline sample at zero magnetic field and under fields were carried. A characteristic elastic softening of the transverse modulus C66 originating from a quadrupole interaction was found. The crystal electric field parameters were determined to reproduce C66, magnetic susceptibilities, and magnetization curves. The obtained level scheme is that the ground and first excited states are singlets, despite the existence of both the magnetic transition and the quadrupole interaction, indicating that Tb3Ru4Al12 is a curious compound. The positive sign of the quadrupole-quadrupole coupling constant for C66 indicates a ferroquadrupolar-type interaction of the electric quadrupole Oxy or O2 . The anisotropic magnetic field dependencies of TN in the field along [100] and [001] were also clarified.

Permalink: https://www.hzdr.de/publications/Publ-30927
Publ.-Id: 30927


The role of microorganisms in the bentonite barrier of high-level radioactive waste repositories

Matschiavelli, N.; Dressler, M.; Neubert, T.; Kluge, S.; Schierz, A.; Cherkouk, A.

The global production of 12,000 metric tonnes of high-level radioactive waste (HLW) every year is a big challenge with respect to its safe long-term storage. In the favored multi-barrier system, bentonite is used as a geo-technical barrier in many disposal programs worldwide. The bentonite seals the space between the canister containing the HLW and the surrounding host rock, thereby fulfilling two major tasks: 1) slow down the process of corrosion when water enters the disposal site, and 2) hinder the discharge of radionuclides into the bio-geosphere in case of a leaking canister. Due to their metabolic activity, microorganisms could influence the properties of the bentonite barrier. In order to investigate the metabolic potential of naturally occurring microorganisms, we conducted anaerobic bentonite-slurry experiments containing uncompact bentonite and a synthetic Opalinus Clay pore water solution. Within one-year incubation at 30 and 60 °C, lactate- or H2-stimulated microcosms at 30 °C showed the dominance and activity of strictly anaerobic, sulfate-reducing and spore-forming microorganisms. Consequently, hydrogen sulfide gas was generated in the respective set ups, leading to the formation of fractures and iron-sulfur precipitations. Experiments that incubated at 60 °C, showed the dominance of thermophilic bacteria, independent of the presence of substrates. The respective set ups showed no significant changes in the analyzed bio-geochemical parameters. The obtained results clearly show that indigenous microorganisms evolve in a temperature- and substrate-dependent manner. The formed metabolites can potentially affect the dissolution behavior of minerals and ions within the bentonite as well as the corrosion process of the canister material and require further investigations.

  • Open Access Logo Lecture (Conference) (Online presentation)
    EGU General Assembly 2020, 04.-08.05.2020, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30926
Publ.-Id: 30926


Solid-liquid Flow in Stirred Tanks: Euler-Euler / RANS Modeling

Shi, P.; Rzehak, R.

Stirred tanks are widely used equipment in process engineering. CFD simulations of such equipment on industrial scales are feasible within the Euler-Euler / RANS approach. In this approach, phenomena on particle scale are not resolved and, accordingly, suitable closure models are required. The present work applies a set of closure relations that originates from a comprehensive review of existing results. Focus is on the modeling of interfacial forces which include drag, lift, turbulent dispersion, and virtual mass. Specifically, new models for the drag and lift forces are considered based on the best currently available description. To validate the model a comprehensive set of experimental data including solid velocity and volume fraction as well as liquid velocity and turbulence has been assembled. The currently proposed model compares reasonably well with this dataset and shows generally better prediction compared with other model variants that originate from different combinations of force correlations.

Keywords: stirred tanks; solid-liquid flow; Euler-Euler two-fluid model; closure relations; Reynolds-stress turbulence model

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Permalink: https://www.hzdr.de/publications/Publ-30925
Publ.-Id: 30925


Characterization of blood coagulation dynamics and oxygenation in ex‐vivo retinal vessels by fluorescence hyperspectral imaging

Podlipec, R.; Arsov, Z.; Koklic, T.; Strancar, J.

Blood coagulation mechanisms forming a blood clot and preventing hemorrhage have been extensively studied in the last decades. Knowing the mechanisms behind becomes very important particularly in the case of blood vessel diseases. Real‐time and accurate diagnostics accompanied by the therapy are particularly needed for example in diseases related to retinal vasculature. In our study, we employ for the first time fluorescence hyperspectral imaging (fHSI) combined with the spectral analysis algorithm concept to assess physical as well as functional information of blood coagulation in real‐time. By laser‐induced local disruption of retinal vessels to mimic blood leaking and subsequent coagulation and a proper fitting algorithm, we were able to reveal and quantify the extent of local blood coagulation through direct identification of the change of oxyhemoglobin concentration within few minutes. We confirmed and illuminated the spatio‐temporal evolution of the essential role of erythrocytes in the coagulation cascade as the suppliers of oxygenated hemoglobin. By additional optical tweezers force manipulation, we showed immediate aggregation of erythrocytes at the coagulation site. The presented fluorescence‐based imaging concept could become a valuable tool in various blood coagulation diagnostics as well as theranostic systems if coupled with the laser therapy.

Keywords: Blood coagulation; hemoglobin oxygenation; fluorescence hyperspectral imaging; optical tweezers; comparative animal models; biomedical optics and biophotonics; diagnostics

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Permalink: https://www.hzdr.de/publications/Publ-30922
Publ.-Id: 30922


How to integrate geochemistry at affordable costs into reactive transport for large-scale systems

Stockmann, M.; Brendler, V.

This international workshop entitled “How to integrate geochemistry at affordable costs into reac-tive transport for large-scale systems” was organized by the Institute of Resource Ecology of the Helmholtz-Zentrum Dresden Rossendorf in Feb-ruary 2020. A mechanistic understanding and building on that an appropriate modelling of geochemical processes is essential for reliably predicting contaminant transport in groundwater systems, but also in many other cases where migration of hazardous substances is expected and consequently has to be assessed and limited. In case of already present contaminations, such modelling may help to quantify the threads and to support the development and application of suitable remediation measures. Typical application areas are nuclear waste disposal, environmental remediation, mining and milling, carbon capture & storage, or geothermal energy production. Experts from these fields were brought together to discuss large-scale reactive transport modelling (RTM) because the scales covered by such pre-dictions may reach up to one million year and dozens of kilometers. Full-fledged incorporation of geochemical processes, e.g. sorption, precipitation, or redox reactions (to name just a few important basic processes) will thus create inacceptable long computing times. As an effective way to integrate geochemistry at affordable costs into RTM different geochemical concepts (e.g. multidimensional look-up tables, surrogate functions, machine learning, utilization of uncertainty and sensitivity analysis etc.) exist and were extensively discussed throughout the workshop. During the 3-day program of the workshop keynote and regular lectures from experts in the field, a poster session, and a radio lab tour had been offered. In total, 40 scientists from 28 re-search institutes and 8 countries participated. The focus of the workshop was: (1) To provide and discuss existing geochemical concepts in reactive transport modelling to describe sorption and related retardation processes of contaminants on a variety of sedi-ments and rocks. (2) To explicitly set focus on large-scale natural systems as experienced, e.g., in nuclear waste disposal, carbon capture & storage, environmental remediation, or geothermal applications. (3) To explore how the discussed approaches can be integrated at affordable costs into cur-rent paradigms in THMC models and long-term safety assessments in general. (4) To promote the exchange of scientific knowledge and practical experience between the workshop participants in an efficient way. Based on the intensive discussions and very posi-tive feedback on the workshop, a continuation is intended to bundle and strengthen the respective research activities and stipulate the international network that started to form during the conference days.

Keywords: Geochemistry; Large-scale reactive transport modelling; Workshop

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-111 2020
    ISSN: 2191-8708, eISSN: 2191-8716

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Permalink: https://www.hzdr.de/publications/Publ-30921
Publ.-Id: 30921


Highly efficient targeting of EGFR-expressing tumor cells with UniCAR T cells via target modules based on Cetuximab®

Jureczek, J.; Feldmann, A.; Bergmann, R.; Arndt, C.; Berndt, N.; Koristka, S.; Rodrigues Loureiro, L. R.; Metwasi, N.; Hoffmann, A.; Kegler, A.; Bartsch, T.; Bachmann, M.

Introduction: Since epithelial growth factor receptor (EGFR) overexpression is linked to a variety of malignancies, it is an attractive target for immune therapy including with chimeric antigen receptor (CAR)-engineered T cells. Unfortunately, CAR T cell therapy harbors the risk of severe, even life-threatening side effects. Adaptor CAR T cell platforms such as the previously described UniCAR system might be able to overcome these problems. In contrast to conventional CARs, UniCAR T cells are per se inert. Their redirection towards target cells occurs only in the presence of a tumor-specific target molecule (TM). TMs are bifunctional molecules being able to recognize a tumor-associated antigen (TAA) and to cross-link the CAR T cell via a peptide epitope recognized by the UniCAR domain.
Methods: Here, we compare anti-EGFR TMs: a nanobody (nb)-based αEGFR TM derived from the camelid αEGFR antibody 7C12 with a murine and humanized single-chain fragment variable (scFv) based on the clinically used antibody Cetuximab®.
Results: In principle, both the nb- and scFv-based TM formats are able to redirect UniCAR T cells to eliminate EGFR-expressing tumor cells in an antigen-specific and TM-dependent manner. However, the scFv-based αEGFR TM was significantly superior to the nb-based TM especially with respect to lysis of tumor cells.
Discussion: Improved efficiency of the scFv-based TM allowed the redirection of UniCAR T cells towards tumor cells expressing high as well as low EGFR levels in comparison to nb-based αEGFR TMs.

Keywords: EGFR; UniCAR; CAR T cells; adaptor CARs; solid tumors; immunotherapy

Permalink: https://www.hzdr.de/publications/Publ-30919
Publ.-Id: 30919


Data for: Photoluminescence dynamics in few-layer InSe

Venanzi, T.; Arora, H.; Winnerl, S.; Pashkin, O.; Chava, P.; Patane, A.; Kovalyuk, Z.; Kudrynskyi, Z.; Watanabe, K.; Taniguchi, T.; Erbe, A.; Helm, M.; Schneider, H.

We study the optical properties of thin flakes of InSe encapsulated in hexagonal boron nitride. Mores pecifically, we investigate the photoluminescence (PL) emission and its dependence on sample thickness and temperature. Through the analysis of the PL line shape, we discuss the relative weights of the exciton and electron-hole contributions. Thereafter we investigate the PL dynamics. Two contributions are distinguishable at low temperature: direct band-gap electron-hole and defect-assisted recombination. The two recombination processes have lifetimes ofτ1∼8ns andτ2∼100 ns, respectively. The relative weights of the direct band-gap and defect-assisted contributions show a strong layer dependence due to the direct-to-indirect band-gap crossover. Electron-hole PL lifetime is limited by population transfer to lower-energy states and no dependence on the number of layers was observed. The lifetime of the defect-assisted recombination gets longer for thinner samples. Finally, we show that the PL lifetime decreases at high temperatures as a consequence of more efficient nonradiative recombinations.

Keywords: 2D semiconductors; time-resolved photoluminescence

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-04-14
    DOI: 10.14278/rodare.412
    License: CC-BY-1.0

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Permalink: https://www.hzdr.de/publications/Publ-30918
Publ.-Id: 30918


Photoluminescence dynamics in few-layer InSe

Venanzi, T.; Arora, H.; Winnerl, S.; Pashkin, O.; Chava, P.; Patanè, A.; Kovalyuk, Z. D.; Kudrynskyi, Z. R.; Watanabe, K.; Taniguchi, T.; Erbe, A.; Helm, M.; Schneider, H.

We study the optical properties of thin flakes of InSe encapsulated in hexagonal boron nitride. More specifically, we investigate the photoluminescence (PL) emission and its dependence on sample thickness and temperature. Through the analysis of the PL line shape, we discuss the relative weights of the exciton and electron-hole contributions. Thereafter we investigate the PL dynamics. Two contributions are distinguishable at low temperature: direct band-gap electron-hole and defect-assisted recombination. The two recombination processes have lifetimes ofτ1∼8ns andτ2∼100 ns, respectively. The relative weights of the direct band-gap and defect-assisted contributions show a strong layer dependence due to the direct-to-indirect band-gap crossover. Electron-hole PL lifetime is limited by population transfer to lower-energy states and no dependence on the number of layers was observed. The lifetime of the defect-assisted recombination gets longer for thinner samples. Finally, we show that the PL lifetime decreases at high temperatures as a consequence of more efficient nonradiative recombinations.

Keywords: 2D semiconductors; time-resolved photoluminescence

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Permalink: https://www.hzdr.de/publications/Publ-30917
Publ.-Id: 30917


Two-Pion production in the second resonance region in π−p collisions with HADES

Adamczewski-Musch, J.; Arnold, O.; Atomssa, E. T.; Behnke, C.; Belounnas, A.; Belyaev, A.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Chernenko, S.; Chlad, L.; Chudoba, P.; Ciepał, I.; Deveaux, C.; Dittert, D.; Dreyer, J.; Epple, E.; Fabbietti, L.; Fateev, O.; 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.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Kämpfer, B.; Kardan, B.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kornas, F.; Kotte, R.; Kuboś, J.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Linev, S.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Malige, A.; Markert, J.; Maurus, S.; Metag, V.; Michel, J.; Mihaylov, D. M.; Mikhaylov, V.; Morozov, S.; Müntz, C.; Münzer, R.; Naumann, L.; Nowakowski, K.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petukhov, O.; Pietraszko, J.; Prozorov, A. P.; Przygoda, W.; Ramstein, B.; Rathod, N.; Reshetin, A.; Rodriguez-Ramos, P.; Rost, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schmidt-Sommerfeld, K.; Schuldes, H.; Schwab, E.; Scozzi, F.; Seck, F.; Sellheim, P.; Siebenson, J.; Silva, L.; Sing, U.; Smyrski, J.; Spataro, S.; Spies, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Szala, M.; Tlusty, P.; Traxler, M.; Tsertos, H.; Ungethüm, C.; Vazquez-Doce, O.; Wagner, V.; Wendisch, C.; Wiebusch, M. G.; Wirth, J.; Wójcik, D.; Zanevsky, Y.; Zumbruch, P.

Pion induced reactions provide unique opportunities for an unambiguous description of baryonic resonances and their coupling channels by means of a partial wave analysis. Using the secondary pion beam at SIS18, the two pion production in the second resonance region has been investigated to unravel the role of the N(1520)32− resonance in the intermediate ρ production. Results on exclusive channels with one pion (π−p) and two pions (π+π−n, π0π−p) in the final state measured in the π−−p reaction at four different pion beam momenta (0.650, 0.685, 0.733, and 0.786 GeV/c) are presented. The excitation function of the different partial waves and Δπ, Nσ and Nρ isobar configurations is obtained, using the Bonn-Gatchina partial wave analysis. The N(1520)32− resonance is found to dominate the Nρ final state with the branching ratio BR=12.2±1.9%.

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Permalink: https://www.hzdr.de/publications/Publ-30916
Publ.-Id: 30916


Argon gas flow investigations in liquid Sodium using ultrafast electron beam X-ray computed tomography (NaFEX) - Data set

Bieberle, A.
DataCollector: Barthel, Frank; DataCollector: Sprewitz, Uwe; DataCurator: Bieberle, Martina; DataManager: Bieberle, André; Project Member: Gundrum, Thomas; Project Member: Räbiger, Dirk; RelatedPerson: Eckert, Sven; Project Member: Neumann-Kipping, Martin

For investigations on Argon gas bubbles in liquid Sodium ultrafast electron beam X-ray computed tomography is applied. The repository comprises imaging data obtained at

  • different heights of the test facility and
  • various gas volume rates.

The CT scanner is operated in dual-plane mode with a deflection frequency of 2 kHz for approximately 30s.

Keywords: ultrafast X-ray CT; gas-liquid two-phase flow

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-04-16
    DOI: 10.14278/rodare.291
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-30915
Publ.-Id: 30915


Measurements to verify different concepts of multi-plane detectors for ultrafast electron beam X-ray computed tomography

Bieberle, A.
Project Member: Barthel, Frank; Project Member: Windisch, Dominic; DataCollector: Bieberle, André

The measurements in this dataset repository contain raw signal data obtained from novel multi-plane detectors that are experimentally tested with the ultrafast electron beam X-ray CT (UFXCT) scanner at the HZDR. The CT scanner is operated with a constant deflection frequency of 2 kHz, an acceleration voltage of +150 keV and in dual-plane CT scanning mode. The voltage output signals of four multi-plane detector channels are sampled with 2 MHz and 24 bit (±5 V) using a commercial eight-channel data acquisition system (LTT24, Labortechnik Tasler GmbH). The applied reverse voltage to the avalanche photodiodes and the three deflection coil signals are recorded simultaneously. The detectors are collimated with lead and are analysed for

  • various electron beam currents,
  • various detector heights and
  • two different designs.

Keywords: ultrafast X-ray CT; scintillation detectors; multi-plane imaging

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-04-17
    DOI: 10.14278/rodare.288
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-30914
Publ.-Id: 30914


Voxel-based finite element modelling of wood elements based on spatial density and geometry data using computed tomography

Hartig, J. U.; Bieberle, A.; Engmann, C.; Haller, P.

In this paper, voxel-based finite element modelling based on spatial geometry and density data is applied to simulate the detailed stress and strain distribution in a large wooden element. As example, a moulded wooden tube with a length of 3 m and a diameter of 0.3 m is examined. Gamma-ray computed tomography is used to obtain the spatial distribution of elastic properties based on the correlation with density. Correlation functions between density and elastic material properties are experimentally determined and serve as link for defining the non-uniform distribution of the material properties in the finite element model. Moreover, also the geometry is obtained by the computed tomography. Due to the consideration of both the geometric imperfections and the spatial variation of the material properties, a detailed analysis of the stress and strain distribution of the wood element is performed. Additionally, a non-destructive axial compression test is performed on the wooden tube to analyse the load-bearing behaviour. By means of digital image correlation, the deformation of the surface is obtained, which also serves for validation of the finite element model.

Keywords: large wooden elements; gamma-ray computed tomography; finite element model

Related publications

  • Wood Research and Technology - Holzforschung 75(2021)8, 742-753
    Online First (2021) DOI: 10.1515/hf-2020-0105

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  • Secondary publication expected from 08.01.2022

Permalink: https://www.hzdr.de/publications/Publ-30913
Publ.-Id: 30913


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