Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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31542 Publications
Flüssigmetallbatterien als Großspeicher - Technologie, Scale-Up und Optionen zur Sektorkopplung
Nimtz, M.;
Es werden die grundsätzlichen Eigenschaften von Flüssigmetallbatterien beschrieben sowie Methoden und Ergebnisse zum Scale-Up vorgestellt. Des weiteren werden Funktionsweise und Anwendung der LMB-System-Calculator Software erläutert sowie Anwendungsoptionen für Flüssigmetallbbatterien, insbesondere bei der Sektorkoppelung vorgestellt.

Basic properties of Liquid Metal Batteries are described and methods and results for scale-up calculations are presented.
Also, functioning and usage of the LMB-System-Calculator software are discussed and options for the operation of Liquid Metal Batteries, especially for the sector-coupling are presented.
Keywords: LMB, Flüssigmetallbatterien, Scale-Up, Speicher, Sektorkoppelung LMB, liquid metal battery, scale-up, storage, sectro-coupling
  • Lecture (others)
    Energie System 2050 Forschungsthema 1, 1. Workshop 2019, 19.-20.03.2019, Karlsruhe, Deutschland

Publ.-Id: 29014 - Permalink


Synthesis and Biological Investigation of A Novel Fluorine-18 Labeled Benzoimidazotriazine: A Potential Radioligand for In Vivo Phosphodiesterase 2A (PDE2A) PET imaging
Ritawidya, R.; Teodoro, R.; Wenzel, B.; Kranz, M.; Toussaint, M.; Dukic-Stefanovic, S.; Deuther-Conrad, W.; Scheunemann, M.; Brust, P.;
Objectives: Cyclic nucleotide phosphodiesterase 2A (PDE2A), an enzyme which hydrolyzes the second messengers cAMP and cGMP, is highly enriched in distinct areas of the brain. Accordingly, PDE2A is involved in important signaling pathways related to normal brain function but also to
neurodegeneration and neuro-oncology [1]. To enable the visualization of this protein in the brainwith PET, we developed a novel fluorine-18 radioligand for PDE2A.
Methods: Based on the benzoimidazotriazine (BIT) tricyclic scaffold, several fluorine-containing derivatives were synthesized via a multi-step synthesis route, and their inhibitory profiles were assessed by PDE isoenzyme-specific activity assays. The most potent and selective PDE2A ligand
BIT1 was radiolabeled via nucleophilic aromatic substitution of the corresponding 2-nitro pyridine precursor by [18F]fluoride in DMSO with thermal heating (Figure 1). [18F]BIT1 was isolated using semi-preparative HPLC (Reprosil-Pur C18-AQ column, 250 x 10 mm, 46% ACN/aqu. 20 mM
NH4OAc, flow 5.5 mL/min) followed by final purification with solid-phase extraction and formulation in isotonic saline containing 10% ethanol. Preliminary in vitro autoradiography and in vivo PET studies (60 min dynamic PET imaging, nanoScan® PET/MRI, MEDISO, Budapest, Hungary) of [18F]BIT1 were performed using pig brain slices and female CD-1 mice, respectively. The in vivo metabolism of [18F]BIT1 was investigated by radio-HPLC analysis of mouse plasma and brain samples at 30 min p.i.
Results: From the series of BIT derivatives, BIT1 was selected as candidate for PET imaging of PDE2A based on the most suitable inhibitory potential and profile (IC50 PDE2A3 = 3.3 nM;16-fold selectivity over PDE10A). [18F]BIT1 was successfully synthesized with a radiochemical yield of 54 ± 2% (n = 3, EOB), molar activities of 155 – 175 GBq/μmol (EOS) and radiochemical purities of ≥99%. [18F]BIT1 was stable in saline, pig plasma, and n-octanol up to 60 min at 37 °C. The distribution pattern of [ 18F]BIT1 in pig brain cryosections corresponds to the spatial distribution of PDE2A with accumulation in the striatal regions caudate nucleus and nucleus accumbens. Additionally, the displacement of [18F]BIT1 with BIT1 as well as TA1 (a potent PDE2A ligand) indicated saturability and selectivity of these binding sites. Uptake of [18F]BIT1 in the brain was shown by subsequent imaging studies in mice (SUVwhole brain = 0.7 at 5 min p.i.); however, more detailed analyses revealed nonspecific distribution of the tracer in the brain (78% parent compound at 30 min p.i.).
Conclusions: The potent and selective PDE2A inhibitor [18F]BIT1 binds in vitro in brain regions known to express PDE2A. Further structural modifications will be performed to develop radiotracers with improved brain uptake and target-selective accumulation in vivo.
Acknowledgement
1. Deutsche Forschungsgemeinschaft (German Research Foundation, SCHE 1825/3-1).
2. Scholarship Program for Research and Innovation in Science and Technology Project
(RISET-PRO)-Indonesia Ministry of Research, Technology and Higher Education (World
Bank Loan No: 8245-ID)

References
[1] S. Schröder, B. Wenzel, W. Deuther-Conrad, M. Scheunemann, P. Brust, Novel Radioligands
for Cyclic Nucleotide Phosphodiesterase Imaging with Positron Emission Tomography: An Update
on Developments Since 2012, Molecules 21 (2016) 650–685.
Keywords: Phosphodiesterases, positron emission tomography, molecular imaging, benzoimidazotriazines
  • Poster
    International Symposium in Radiopharmaceutical Sciences, 26.-31.05.2019, Beijing, China

Publ.-Id: 29007 - Permalink


Solving the Kuramoto Oscillator Model on Random Graphs
Kelling, J.ORC; Ódor, G.ORC; Gemming, G.
The problem of synchronization is recently attracting much attention because it relates to current topics in science. The dynamics of electrical grids can be affected by de-synchronizations between supplier and consumer nodes. In brains, synchronization of neuronal activity plays an important role in most functions. The Kuramoto model describes systems of coupled oscillators which, which exhibit non-trivial behavior on complex graphs, making it a suitable tool to study the synchronization dynamics of brains an other systems.

Numerical solution of Kuramoto type ordinary differential equations for long times and large systems requires strong computation power, due to the inherent chaoticity of this nonlinear system.

This poster presents a GPU implementation of a solver achieving large speedups over CPU on sparse random graphs. The key to performance here, is the presented memory layout which supplements the SIMT usage of our design.

# extended abstract
The problem of synchronization is recently attracting much attention because it relates to current topics in science. The dynamics of electrical grids can be affected by de-synchronizations between supplier and consumer nodes. In brains, synchronization of neuronal activity plays an important role in most functions.

Using the Kuramoto model[1], we are studying a range of problems, from basinc questions about synnchronisation transitions on disordered lattices and random graphs to problems mentioned in the short abstract. The model shows komplex behavior on human connectome graph, which allow the study of synchronization in the human brain[2]. An extension of the model allows modeling power grid networks[3,4].

Very intensive Simulations are required to obtain precise result especiall near criticality, which these systems show at synchronization transitons. To enable the study of these systems at sufficent precision, we implemented a GPU code, which we are presenting in this poster. To this end we used boost::odeint to get the standart numerical integartion out of the way an focus on the most performance critical aspect: the evaluation of the model itself. The key to our implementation is the choice of SIMT vectorization and a suitable memory layout, which are presented in the poster. The aspects also remain the same, when we add the extension to the second-order Kuramoto Model[2], which is required to model powergrids.

[1] Kuramoto, Y. In Araki, H. (ed.) Mathematical Problems in Theoretical Physics, vol. 39 of Lecture Notes in Physics, Berlin, 420
[2] Villegas, P., Moretti, P. & Muñoz, M. A. Scientific Reports 4, 5990 (2014).
[3] Filatrella, G., Nielsen, A. H. & Pedersen, N. F. Eur. Phys. J. B 61, 485–491 (2008)
[4] Ódor, G. & Hartmann, B. Phys. Rev. E 98, 022305 (2018).
Keywords: GPGPU, random graph, Kuramoto model
  • Poster
    GTC 2019 Silicon Valley, 17.-21.03.2019, San Jose, CA, USA

Publ.-Id: 29004 - Permalink


Time efficient scatter correction for time-of-flight PET: the immediate scatter approximation
Nikulin, P.ORC; Maus, J.ORC; Hofheinz, F.ORC; Lougovski, A.; van den Hoff, J.ORC
Utilization of Time-Of-Flight (TOF) information allows to improve image quality and convergence rate in iterative PET image reconstruction. In order to obtain quantitatively correct images accurate scatter correction (SC) is required that accounts for the non-uniform distribution of scatter events over the TOF bins. However, existing simplified TOF-SC algorithms frequently exhibit limited accuracy while the currently accepted gold standard — the TOF extension of the single scatter simulation approach (TOF-SSS) — is computationally demanding and can substantially slow down the reconstruction. In this paper we propose and evaluate a new accelerated TOF-SC algorithm in order to improve this situation. The key idea of the algorithm is the use of an immediate scatter approximation (ISA) for scatter time distribution calculation which speeds up estimation of the required TOF scatter by a factor of up to five in comparison to TOF-SSS. The proposed approach was evaluated in dedicated phantom measurements providing challenging high activity contrast conditions as well as in representative clinical patient data sets. Our results show that ISA is a viable alternative to TOF-SSS. The reconstructed images are in excellent quantitative agreement with those obtained with TOF-SSS while overall reconstruction time can be reduced by a factor of two in whole-body studies, even when using a listmode reconstruction not optimized for speed.
Keywords: PET, Scatter Correction, Immediate Scatter Approximation, Image Reconstruction, TOF, SSS, TOF-SSS, TOF-SC, ISA

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Publ.-Id: 28997 - Permalink


Protecting Pulsed High-Power Lasers with Real-Time Object Detection
Kelling, J.; Gebhardt, R.; Helbig, U.; Bock, S.; Schramm, U.; Juckeland, G.;
In Petawatt laser systems, firing at 10Hz, suddenly appearing scatterers can damage components. Damage(-spreading) can be avoided by suspending operation immediately on occurrence of such an event. This poster presents our approach for the automatic detection of critical failure states in real-time, employing state-of-the-art object localization on intensity profiles of the laser beam.

Learn, how we fitted the You Look Only Once (YOLO) approach, which is suited to low-latency object detection, to our problem and how we adapted the required multi-step training protocol to the available experimental data.
In this application accuracy trumps high recall, as false positives would severely impede productivity or even render our system useless. This had us refrain from general anomaly detection and thus we also present different ways in which we tune the object-detection for minimal false-positive rates.

# extended abstract
High-power lasers are operated at our research center for investigations of exotic states of matter and medical applications, among others. This project to improve the automatic shutdown/interlock system of two lasers (one in operation, one currently under construction) has the goal of reducing the probability of, potentially expensive, damage-spreading scenarios, while at the same time avoiding false alarms. In order to achieve high precision, we train for high recall only for known indicators, instead of using anomaly detection.

After we presented a proof-of-concept for this type of failure-state-detection at GTC 2018, where the main challenge was in dealing with a far too small dataset, we are now working on a pure deep-learning approach driven by systematic experimental data. In the new design, intended for production use, the classification takes place on differences between a running average of non-signaling images and the current shot. This is required, because no images can be obtained which can be classified as "good" without context. In order to achieve fast object-detection, to highlight potential problems for the operator, the you look only once (YOLO) approach[1], which we modify by removing the final layers for bounding-box prediction and train the network to directly produce an expressive feature map (lazy YOLO).

From this talk, the audience can learn how we adapted the well-known YOLO approach to our real-world application, from the employed network to the multi-step training protocol. Another topic is the design for short response times, to which end we employ Caffe, OpenCV on GPU and use C++ as main programming language instead of python.

[1] Redmon, J., Farhadi, A.: YOLO9000: Better, Faster, Stronger, ArXiv e-prints, 2016
Keywords: Image Classification, Caffe, automatic Laser-safety shutdown, Object Detection
  • Poster
    GTC 2019 Silicon Valley, 17.-21.03.2019, San Jose, CA, USA

Publ.-Id: 28992 - Permalink


A Polka-Dot Pattern Emerges in Superfluid Helium
Wosnitza, J.;
A surprising two-dimensional pattern appears in superfluid helium-3 when the liquid is confined to a micrometer-thick cell and exposed to a magnetic field.

Publ.-Id: 28989 - Permalink


Low anisotropic upper critical fields in SmO1−xFxFeAs thin films with a layered hybrid structure
Haindl, S.; Kampert, E.; Sasase, M.; Hiramatsu, H.; Hosono, H.;
We report on the upper critical fields in SmO1−xFxFeAs thin films prepared by pulsed laser deposition. With an F-content gradient along their thickness, the films could be described approximately as layered two-phase hybrid structures comprised of one superconducting layer and one antiferromagnetic layer. An analytical characterization of different thin film samples by Auger electron spectroscopy and energy-dispersive x-ray spectroscopy in scanning transmission electron microscopy is provided and structural defects, such as antiphase boundaries, were confirmed for films grown at lower deposition temperatures. Electrical transport measurements in pulsed magnetic fields yielded upper critical fields higher than 80 T with an anisotropy γHc2 ≤ 2.25.

Publ.-Id: 28988 - Permalink


Photogeneration of Manganese(III) from Luminescent Manganese(II) Complexes with Thiacalixarene Ligands: Synthesis, Structures and Photophysical Properties
O'Toole, N.; Lecourt, C.; Suffren, Y.; Hauser, A.; Khrouz, L.; Jeanneau, E.; Brioude, A.; Luneau, D.; Desroches, C.;
The photophysical properties of the compound [(ThiaSO₂)(MnII)₂(DMF)₄(H₂O)₂] (2), ThiaSO₂ = p-tert-butylsulfonylcalix[4]arene, are presented and compared to the ones of [(ThiaSO₂)₂(MnII)₄F]K (1). The orange luminescence of 2 is attributed, as for 1, to the MnII centred ⁴T₁→⁶A₁ transition and shows, for this type of complex, the weak influence of the Mn²⁺ coordination and ThiaSO₂ conformation on this luminescence, the temperature and pressure dependence and quenching bymolecular dioxygen of which are reported for 2. The latter is attributed to energy transfer from the ⁴T₁ state exciting dioxygen to its ⁱΣ⁺ᵍ state and is responsible for the photosynthesis of the [(ThiaSO₂)(MnIII)(DMF)₂]Na (3) complex in DMF solution from 1 or 2. This reaction was studied by UV/Visible and EPR spectroscopy. The molecular structure and EPR spectroscopy of 3 are also presented.
Keywords: Thiacalixarene, Luminescence, Photooxidation, Manganese

Publ.-Id: 28984 - Permalink


Strong and Selective Ni(II) Extractants Based on Synergistic Mixtures of Sulfonic Acids and Bidentate N-Heterocycles
Roebuck, J. W.; Bailey, P. J.; Doidge, E. D.; Fischmann, A. J.; Healy, M. R.; Nichol, G. S.; O'Toole, N.; Pelser, M.; Sassi, T.; Sole, K. C.; Tasker, P. A.;
Bidentate 5,5ʹ-alkyl-3,3ʹ-bi-1H-pyrazole and 2-(5-alkyl-1H-pyrazol-3-yl)pyridine ligands, L⁵ and L⁶ , have been shown to be stronger synergists for the solvent extraction of Ni(II) from sulfate solutions by dinonylnaphthalene sulfonic acid (DNNSAH) than the structurally related tridentate ligand 2,6-bis-[5-n-nonylpyrazol-3-yl]pyridine, L¹ , previously reported by Zhou and Pesic. The bidentate ligands are highly selective, providing the option of sequential recovery of Ni(II) and Co(II) and rejection of other metals commonly found in the liquors resulting from the acidic sulfate leaching of laterite ores. They were the strongest synergists identified in a screening carried out on 18 types of bidentate and tridentate N-heterocyclic ligands, including the recently reported 2-(2ʹ-pyridyl)imidazoles, L⁹⁻¹¹ . X-ray crystal structures of Ni(II) complexes of model ligands for L⁵ and L⁶ , having t-butyl rather than long-chain alkyl groups and with 2-naphthalene sulfonate rather than DNNSA⁻ as counteranions, show that the [Ni(L)₃ ]²⁺ complexes form strong H-bonds from the pyrazolyl NH groups to the oxygen atoms of the sulfonate groups, an arrangement that will stabilize [Ni(L)₃ ·(DNNSA)₂ ] assemblies and shield their polar functionalities from diluent molecules of the water-immiscible phase. UV–visible spectra and mass spectrometry provide evidence for the strong synergists displacing all water molecules from the inner coordination sphere of the Ni(II) ions.
Keywords: Ni recovery, laterite processing, synergistic solvent extraction, outer-sphere bonding, supramolecular chemistry

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  • Secondary publication expected from 02.11.2019

Publ.-Id: 28983 - Permalink


Compliance-current-modulated resistive switching with multi-level resistance states in single-crystalline LiNbO3 thin film
Pan, X.; Shuai, Y.; Wu, C.; Luo, W.; Sun, X.; Zeng, H.; Guo, H.; Yuan, Y.; Zhou, S.; Böttger, R.; Cheng, H.; Zhang, J.; Zhang, W.; Schmidt, H.;
Resistive switching behavior of a ca. 600 nm thick single-crystalline LiNbO3 (LNO) film has been investigated after vacuum-annealing. Oxygen vacancies (OVs) were generated in the LNO thin film during the annealing process. After electro-forming, filamentary resistive switching has been observed, and the performance of switching can be tuned by the compliance current level. Multi-level resistance states including four different low resistance states, were realized by setting different compliance currents, revealing that both concentration of OVs within the conductive filament and the geometry of the conductive filament influence the switching behavior. The conduction mechanisms of the charge transport during switching is discussed based on the current-voltage curves.

Publ.-Id: 28976 - Permalink


Proton irradiation induced defects in β-Ga2O3: A combined EPR and theory study
Bardeleben, H.; Zhou, S.; Gerstmann, U.; Skachkov, D.; Lambrecht, W.; Ho, Q.; Deák, P.;
Proton irradiation of both n-type and semi-insulating bulk samples of β-Ga2O3 leads to the formation of two paramagnetic defects with spin S = 1/2 and monoclinic point symmetry. Their high introduction rates indicate them to be primary irradiation induced defects. The first electron spin resonance (EPR1) has a g-tensor with principal values of gb = 2.0313, gc = 2.0079, and ga* = 2.0025 and quasi-isotropic superhyperfine interaction of 13G with two equivalent Ga neighbors. Under low temperature photoexcitation, this defect is quenched and replaced by a different metastable spin S = 1/2 center of comparable intensity. This second defect (EPR2) has similar principal g-values of gb = 2.0064, gc = 2.0464, and ga* = 2.0024 and shows equally superhyperfine interaction with two equivalent Ga atoms. This EPR2 defect is stable up to T = 100 K, whereas for T > 100 K the initial defect is recovered. Density functional theory calculations of the spin Hamiltonian parameters of various intrinsic defects are carried out using the gauge including projector augmented wave method in order to determine the microscopic structure of these defects. The intuitive models of undistorted gallium monovacancies or self-trapped hole centers are not compatible with neither of these two defects.

Publ.-Id: 28975 - Permalink


Double-peak specific heat and spin freezing in the spin-2 triangular lattice antiferromagnet FeAl2Se4
Li, K.; Jin, S.; Guo, J.; Xu, Y.; Su, Y.; Feng, E.; Liu, Y.; Zhou, S.; Ying, T.; Li, S.; Wang, Z.; Chen, G.; Chen, X.;
We report the properties of a triangular lattice iron-chalcogenide antiferromagnet FeAl2Se4.The spin susceptibility reveals a significant antiferromagnetic interaction with a Curie-Weiss temperature Θ_CW≃−200K and a spin-2 local moment. Despite a large spin and a large ∣Θ_CW∣, the low-temperature behaviors are incompatible with conventional classical magnets. No long-range order is detected down to 0.4 K. Similar to the well-known spin-1 magnet NiGa2S4, the specific heat of FeAl2Se4 exhibits a double-peak structure and a T2 power law at low temperatures, which are attributed to the underlying quadrupolar spin correlations and the Halperin-Saslow modes, respectively. The spin freezing occurs at ∼14 K, below which the relaxation dynamics is probed by the ac susceptibility. Our results are consistent with the early theory for the spin-1 system with Heisenberg and biquadratic spin interactions. We argue that the early proposal of the quadrupolar correlation and gauge glass dynamics may be well extended to FeAl2Se4. Our results provide useful insights about the magnetic properties of frustrated quantum magnets with high spins.

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Publ.-Id: 28974 - Permalink


Oxyhydride Nature of Rare-Earth-Based Photochromic Thin Films
Cornelius, S.; Colombi, G.; Nafezarefi, F.; Schreuders, H.; Heller, R.; Munnik, F.; Dam, B.;
Thin films of rare-earth (RE)−oxygen−hydrogen compounds prepared by reactive magnetron sputtering show a unique color-neutral photochromic effect at ambient conditions. While their optical properties have been studied extensively, the understanding of the relationship between photochromism, chemical composition, and structure is limited. Here we establish a ternary RE−O−H composition-phase diagram based on chemical composition analysis by a combination of Rutherford backscattering and elastic recoil detection. The photochromic films are identified as oxyhydrides with a wide composition range described by the formula REOxH3−2x where 0.5 ≤ x ≤ 1.5. We propose an anion-disordered structure model based on the face-centered cubic unit cell where the O2− and H− anions occupy tetrahedral and octahedral interstices. The optical band gap varies continuously with the anion ratio, demonstrating the potential of band gap tuning for reversible optical switching applications.

Publ.-Id: 28973 - Permalink


Extension of the nodal code DYN3D to SFR applications
Nikitin, E.;
DYN3D is a well-established Light Water Reactor (LWR) simulation tool and is being extended for safety analyses of Sodium cooled Fast Reactors (SFRs) at the Helmholtz-Zentrum Dresden-Rossendorf. This thesis focuses on the first stage of the development process, that is, the extension and application of DYN3D for steady-state and transient SFR calculations on reactor core level. In contrast to LWRs, the SFR behavior is especially sensitive to thermal expansions of the reactor components. Therefore, a new thermal-mechanical module accounting for thermal expansions is implemented into DYN3D. At first step, this module is capable of treating two important thermal expansion effects occurring within the core, namely axial expansion of fuel rods and radial expansion of diagrid. In order to perform nodal calculations with DYN3D, pre-generated homogenized few-group cross sections (XS) are necessarily needed. Therefore, prior to the development of thermal expansion models, a general methodology for XS generation is established for SFR nodal calculations based on the use of the Monte Carlo code Serpent. The new methodological developments presented in this thesis are verified against the Monte Carlo solutions of Serpent. Two SFR cores are used for testing: the large oxide core of the OECD/NEA benchmark and a smaller core from the Phenix end-of-life tests. Finally, the extended DYN3D is validated against selected IAEA benchmark tests on the Phenix end-of-life experiments that contain both steady-state and transient calculations. The contribution to the SFR-related developments at the HZDR, as presented in this thesis, makes it possible of performing steady-state and transient calculations for SFRs on reactor core level by using DYN3D. With this study, the basis of the next stage of DYN3D developments is established, that is, the up-scale of SFR analysis to system level can continue by coupling with a sodium capable thermal-hydraulic system code.
Keywords: SFR ; thermal expansion ; group constant generation ; nodal methods ; spatial kinetics ; Monte Carlo ; Serpent ; DYN3D

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Publ.-Id: 28972 - Permalink


Fast-neutron-induced fission cross section of Pu(242) measured at the neutron time-of-flight facility nELBE
Kögler, T.ORC

This dataset includes the processed data of the fast neutron-induced fission of Pu(242) experiement performed in November 2014 at the neutron time-of-flight facility nELBE which was published in T. Kögler et al., Phys. Rev. C 99, 024604

It contains the absolute (Pu242_nfis_Koegler_2019.csv) and relative (Pu242_U235_nfis_Koegler_2019.csv) cross section data ranging from 0.5 MeV to 10 MeV. The cross section data is given in comma separated ASCII files, as well as in a MS Excel-Sheet.

The columns of the tables are defined as follows:

  1. EN...neutron kinetic energy from the measured time of flight (ToF)
  2. EN-ERR...uncertainty of neutron kinetic energy = 0.5*(ToF bin width) = 1 ns
  3. DATA...cross section data
  4. ERR-S...statistical uncertainty of the cross section data
  5. ERR-SY...systematic uncertainty of the cross section data
  6. ERR-T...combined standard uncertainty of the cross section data
  7. ERR-0...relative uncertainty counting
  8. ERR-1...relative uncertainty normalization
  9. ERR-2...relative uncertainty reference cross section
  10. ERR-3...relative uncertainty FF detection inefficiency
  11. ERR-4...relative stat. uncertainty scattering correction H19
  12. ERR-5...relative sys. uncertainty scattering correction H19
  13. ERR-6...relative stat. uncertainty scattering correction PuFC
  14. ERR-7...relative sys. uncertainty scattering correction PuFC

Additionally, a root (see https://root.cern.ch/) file is supplied, including the determined cross sections and all nessessary data to reconstruct the experiment. This includes the measured quantities, reference data, correction factors, evaluated cross sections etc.

To have the whole functionality of the root file, additional libary files (libGo4UserAnalysis.rootmaplibGo4UserAnalysis.so and libGo4UserAnalysis_rdict.pcm) are also given here.

Keywords: neutron-induced fission; plutonium-242; cross section measurements; nuclear reactions; nucleon induced nuclear reactions; nELBE
Related publications
Fast-neutron-induced fission cross section of Pu(242) … (Id 28878) has used this publication of HZDR-primary research data
Die Bestimmung des neutroneninduzierten Spaltquerschnitts … (Id 26338) has used this publication of HZDR-primary research data
  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-03-06
    DOI: 10.14278/rodare.117
    License: CC-BY-4.0

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Publ.-Id: 28970 - Permalink


Supplementary Data: Spectral Control via Multi-Species Effects in PW-Class Laser-Ion Acceleration
Huebl, A.ORC; Rehwald, M.ORC; Obst-Huebl, L.ORC; Ziegler, T.ORC; Garten, M.ORC; Widera, R.ORC; Zeil, K.; Cowan, T. E.ORC; Bussmann, M.ORC; Schramm, U.ORC; Kluge, T.ORC

Supplementary materials for our paper "Spectral Control via Multi-Species Effects in PW-Class Laser-Ion Acceleration".

Additional high-resolution, raw HDF5 files using the openPMD standard (DOI:10.5281/zenodo.1167843) increase simulation output data to 4.7 TByte and are available from the corresponding author upon reasonable request. 

Keywords: LPA; laser-ion acceleration; TNSA; multi-species; cryogenic target; particle-in-cell
Related publications
Spectral Control via Multi-Species Effects in PW-Class … (Id 28962) has used this publication of HZDR-primary research data
  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-03-06
    DOI: 10.14278/rodare.115
    License: CC-BY-SA-4.0

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Publ.-Id: 28969 - Permalink


Ion irradiation driven changes of magnetic anisotropy in ultrathin Co films sandwiched between Au or Pt covers
Mazalski, P.; Kurant, Z.; Sveklo, I.; Dobrogowski, W.; Fassbender, J.ORC; Wawro, A.; Maziewski, A.
Modifications of magnetic anisotropy of 30 keV Ga + ion irradiated ultrathin Co films sandwiched between Au or Pt buffer and capping layers are investigated as a function of magnetic layer thickness, d Co , and the ion fluence, F. Maps (d Co , F) of saturation fields have been derived from local magnetooptical polar Kerr effect (PMOKE) measurements. The areas with increased remanent magnetization and/or saturation fields, which are directly related to the uniaxial anisotropy, adopt linear shapes for the two branches in the maps. They are very distinct, especially for the Pt/Co/Pt system irradiated at lower and higher fluence. Replacement of Pt with Au in the buffer layer results in minor influence on the magnetization properties of the irradiated trilayers. Au as a capping layer significantly decreases the anisotropy in the branch appearing at lower fluence. In the Au/Pt/Au sandwich, a severe reduction of induced anisotropy is observed in both branches. The proposed phenomenological model describing experimentally investigated magnetic anisotropies enables separation of surface and volume contributions to both branches of enhanced anisotropy.
Keywords: Chemical driving force demixing, Ion beam irradiation, Magnetooptics, Perpendicular magnetic anisotropy

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Publ.-Id: 28967 - Permalink


SPECT-Untersuchungen mit dem 123 I-markierten Dopamintransporter-Liganden FP-CIT (DaTSCAN):DGN-Handlungsempfehlung (S1-Leitlinie)
Tatsch, K.; Buchert, R.; Bartenstein, P.; Barthel, H.; Boecker, H.; Brust, P.; Drzezga, A.; La Fougère, C.; Gründer, G.; Grünwald, F.; Krause, B.-J.; Kuwert, T.; Langen, K.-J.; Rominger, A.; Sabri, O.; Schreckenberger, M.; Meyer, P. T.;
Die S1-Leitlinie soll bei der Indikationsstellung, Durchführung, Interpretation und Befundung von SPECT-Untersuchungen des Dopamintransporters (DAT) mit DaTSCANTM unterstützen.
Gegenüber der Vorgängerversion von 2007 berücksichtigt die vorliegende Aktualisierung und Überarbeitung die neuere wissenschaftliche Literatur, zwischenzeitlich veröffentlichte Guidelines der europäischen (EANM) und amerikanischen Fachgesellschaften (SNM), sowie die aktuelle Fassung der S3-Leitlinie „Idiopathisches Parkinson-Syndrom“ der Deutschen Gesellschaft für Neurologie. Zudem finden neue technische Möglichkeiten Berücksichtigung.
  • Nuklearmedizin 58(2019)1, 5-16

Publ.-Id: 28965 - Permalink


Source term calculation and validation for F-18 production with a cyclotron for medical applications at HZDR
Konheiser, J.; Mueller, S. E.ORC; Magin, A.; Naumann, B.; Ferrari, A.ORC

Data contained in Fig. 2 of the
publication

Keywords: Cyclotron; Source term; MCNP6; FLUKA
Related publications
Source term calculation and validation for F-18 production … (Id 28971) has used this publication of HZDR-primary research data
  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-03-04
    DOI: 10.14278/rodare.113
    License: CC-BY-4.0

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Publ.-Id: 28964 - Permalink


Effect of four lanthanides onto the viability of two mammalian kidney cell lines
Heller, A.; Barkleit, A.ORC; Bok, F.; Wober, J.
Exposure to lanthanides (Ln) poses a serious health risk to animals and humans. Since Ln are mainly excreted with the urine, we investigated the effect of La, Ce, Eu, and Yb exposure on renal rat NRK-52E and human HEK-293 cells for 8, 24 and 48 h in vitro. Cell viability studies using the XTT assay and microscopic investigations were combined with solubility and speciation studies using ICP-MS and TRLFS. Thermodynamic modeling was applied to predict the speciation of Ln in the cell culture medium. All Ln show a concentration- and time-dependent effect on both cell lines with Ce being the most potent element. In cell culture medium, the Ln are completely soluble and most probably complexed with proteins from fetal bovine serum. The results of this study underline the importance of combining biological, chemical, and spectroscopic methods in studying the effect of Ln on cells in vitro and may contribute to the improvement of the current risk assessment for Ln in the human body. Furthermore, they demonstrate that Ln seem to have no effect on renal cells in vitro at environmental trace concentrations. Nevertheless, especially Ce has the potential for harmful effects at elevated concentrations observed in mining and industrial areas.
Keywords: f-elements; renal cells; cytotoxicity; XTT; time-resolved laser-induced fluorescence spectroscopy; thermodynamic modeling

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  • Secondary publication expected from 22.02.2020

Publ.-Id: 28960 - Permalink


Small-angle neutron scattering (SANS): Overview on principles and best practices
Bergner, F.ORC; Ulbricht, A.
This talk provides an introduction into the method of small-angle neutron scattering (SANS), elements of good practice for the application and analysis as well as selected applications in the field of nuclear materials.
  • Lecture (Conference)
    OECD/NEA Nuclear Science Committee Preparatory meeting: Best practices for nuclear materials characterisation techniques, 11.-12.02.2019, Boulogne-Billancourt, France

Publ.-Id: 28953 - Permalink


Instability of precession driven Kelvin modes: Evidence of a detuning effect
Herault, J.; Giesecke, A.; Gundrum, T.; Stefani, F.;
We report an experimental study of the instability of a nearly resonant Kelvin mode forced by precession in a cylindrical vessel. The instability is detected above a critical precession ratio via the appearance of peaks in the temporal power spectrum of pressure fluctuations measured at the end walls of the cylinder. The corresponding frequencies can be grouped into frequency sets satisfying resonance conditions with the forced Kelvin mode. We show that one set forms a triad that is associated with a parametric resonance of Kelvin modes. We observe a significant frequency variation of the unstable modes with the precession ratio, which can be explained by a detuning mechanism due to the slowdown of the background flow. By introducing a semianalytical model, we show that the departure of the flow from the solid body rotation leads to a modification of the dispersion relation of Kelvin modes and to a detuning of the resonance condition. The second frequency set includes a very low frequency and does not exhibit the properties of a parametric resonance between Kelvin modes. Interestingly, this frequency set always emerges before the occurrence of the triadic resonances, i.e., at a lower precession ratio, which implies that it may correspond to a different type of instability. We discuss the relevance of an instability of a geostrophic mode described by Kerswell [Kerswell, J. Fluid Mech. 382, 283 (1999)], although other mechanisms cannot be completely ruled out.
Keywords: Precession Dynamo DRESDYN

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Publ.-Id: 28944 - Permalink


Mass separated Focused Ion Beams from Liquid Metal Alloy Ion Sources
Bischoff, L.ORC; Mazarov, P.; Pilz, W.; Klingner, N.; Bauerdick, S.; Gierak, J.
Focused Ion Beam (FIB) processing has been developed into a well-established and still promising technique in nearly all fields of nano-technology in particular for direct patterning and proto-typing on the µm scale and well below. Beside new ion source developments based on gas field emission (GFIS), on ionic liquids (ILIS), on magneto-optical traps (MOTIS) or on ICP or ECR sources for Xe-FIB as well as the nearly exclusively used gallium Liquid Metal Ion Sources (LMIS), the replacement of Ga by alloys therein with an adapted FIB optics design can open bright field of new employments. Local ion implantation, ion beam mixing, ion beam synthesis or Focused Ion Beam Lithography (IBL) in the µm- or nm range can benefit from ion species purposely selected in parallel to gallium or noble gases. Therefore, exploring the Liquid Metal Alloy Ion Sources (LMAIS) potential represent a promising alternative to expand the global FIB application fields. Especially, IBL as direct, resistless and three-dimensional patterning enables a simultaneous in-situ process control by cross-sectioning and inspection. Thanks to this nearly half of the elements of the periodic table are made available in the FIB technology as a result of continuous research in this area during the last forty years. Key features of a LMAIS are long life-time, high brightness and stable ion current. Recent developments could make these sources as an alternative technology feasible for nano patterning challenges e.g. to tune electrical, optical, magnetic or mechanic properties.
In this contribution the operation principle, the preparation and testing technology as well as prospective domains for modern FIB applications will be presented. As an example we will introduce a Ga35Bi60Li5 LMAIS in detail. It enables high resolution imaging with light Li ions and sample modification with Ga or heavy polyatomic Bi clusters, all coming from one ion source.
L. Bischoff, P. Mazarov, L. Bruchhaus, and J. Gierak, Appl. Phys. Rev. 3, 021101 (2016).
Keywords: Liquid Metal Alloy Ion Source, Focused Ion Beam, Mass spectra, Cluster ions
  • Lecture (Conference)
    PicoFIB - The International Network for gas Ion Patterning and Microscopy, 13.02.2019, London, Great Britain

Publ.-Id: 28939 - Permalink


Plasmonic field guided patterning of ordered colloidal nanostructures
Huang, X.-P.; Chen, K.; Qi, M.-X.; Zhang, P.-F.; Li, Y.; Winnerl, S.; Schneider, H.; Yang, Y.; Zhang, S.;
Nano-patterned colloidal plasmonic metasurfaces are capable of manipulation of light at the subwavelength scale. However, achieving controllable lithography-free nano-patterning for colloidal metasurfaces still remains a major challenge, limiting their full potential in building advanced plasmonic devices. Here, we demonstrate plasmonic field guided patterning (PFGP) of ordered colloidal metallic nano-patterns using orthogonal laser standing evanescent wave (LSEW) fields. We achieved colloidal silver nano-patterns with a large area of 30 mm² in <10 min by using orthogonal LSEW fields with a non-focused ultralow fluence irradiation of 0.25 W cm⁻². The underlying mechanism of the formation of the nanopatterns is the light-induced polarization of the nanoparticles (NPs), which leads to a dipole-dipole interaction for stabilizing the nano-pattern formation, as confirmed by polarization-dependent surface-enhanced Raman spectroscopy. This optical field-directed self-assembly of NPs opens an avenue for designing and fabricating reconfigurable colloidal nano-patterned metasurfaces in large areas.
Keywords: ordered colloidal nanostructures, plasmonic field guided patterning, polarization stabilizing

Publ.-Id: 28934 - Permalink


Zero-field dynamics stabilized by in-plane shape anisotropy in MgO-based spin-torque oscillators
Kowalska, E.ORC; Kákay, A.ORC; Fowley, C.; Sluka, V.; Lindner, J.; Fassbender, J.ORC; Deac, A. M.
Here, we demonstrate numerically that shape anisotropy in MgO-based spin-torque nano-oscillators consisting of an out-of-plane magnetized free layer and an in-plane polarizer is necessary to stabilize out-of-plane magnetization precession without the need of external magnetic fields. As the in-plane anisotropy is increased, a gradual tilting of the magnetization towards the in-plane easy direction is introduced, favouring zero-field dynamics over static in-plane states. Above a critical value, zero-field dynamics are no longer observed. The optimum ratio of in-plane shape to out-of-plane uniaxial anisotropy, for which large angle out-of-plane zero-field dynamics occur within the widest current range, is reported.
Keywords: spin-torque nano-oscillator (STNO), MgO-based magnetic tunnel junctions, tunnel magnetoresistance (TMR), spin dynamics
Related publications
Tunnel magnetoresistance angular and bias dependence … (Id 27885) is supplemented by this publication

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Publ.-Id: 28927 - Permalink


Singlet ground state in the alternating spin-1/2 chain compound NaVOAsO4
Arjun, U.; Ranjith, K. M.; Koo, B.; Sichelschmidt, J.; Skourski, Y.; Baenitz, M.; Tsirlin, A. A.; Nath, R.;
We present the synthesis and a detailed investigation of structural and magnetic properties of polycrystalline NaVOAsO4 by means of x-ray diffraction, magnetization, electron spin resonance (ESR), and 75As nuclear magnetic resonance (NMR) measurements as well as density-functional band structure calculations. Temperature-dependent magnetic susceptibility, ESR intensity, and NMR line shift could be described well using an alternating spin-1/2 chain model with the exchange coupling J/kB ≃ 52 K and an alternation parameter α ≃ 0.65. From the high-field magnetization measured at T = 1.5 K, the critical field of the gap closing is found to be Hc ≃ 16 T, which corresponds to the zero-field spin gap of Δ0/kB ≃ 21.4 K. Both NMR shift and spin-lattice relaxation rate show an activated behavior at low temperatures, further confirming the singlet ground state. The spin chains do not coincide with the structural chains, whereas the couplings between the spin chains are frustrated. Because of a relatively small spin gap, NaVOAsO4 is a promising compound for further experimental studies under high magnetic fields.

Publ.-Id: 28924 - Permalink


Gaussian and critical scalings in the magnetoconductivity fluctuations of Y3Ba5Cu8O18 superconductor
Dias, F. T.; Vieira, V. N.; Oliveira, C. P.; Silva, D. L.; Mesquita, F.; Lima, J. R.; Wolff-Fabris, F.; Kampert, E.; Pureur, P.;
We have studied the superconducting transition and the magnetoconductivity fluctuations in the polycrystalline Y3Ba5Cu8O18 (Y358) superconductor under magnetic fields upto 1 T. A two-step superconducting transition could be observed as a consequence of the granular structure of the sample, which is strongly affected by the applied magnetic field. Gaussian and genuine critical 3D-XY-E fluctuation regimes were identified. A critical scaling regime beyond 3D-XY was identified for magnetic fields upto 0.25 T, corresponding to the averaged exponent 0.19 and suggesting the occurrence of the weak first-order character of the superconducting transition. In the approximation to the zero resistance a power law regime could be observed, corresponding to the averaged exponent 2.37, which are smaller than previously reported for the Y358 system. Our results are discussed in terms of the Y358 and Yba2Cu3O7−δ (Y123) results in the literature.

Publ.-Id: 28923 - Permalink


Magnetization beyond the Ising limit of Ho2Ti2O7
Opherden, L.; Herrmannsdörfer, T.; Uhlarz, M.; Gorbunov, D. I.; Miyata, A.; Portugall, O.; Ishii, I.; Suzuki, T.; Kaneko, H.; Suzuki, H.; Wonsitza, J.;
We report that the local Ising anisotropy in pyrochlore oxides—the crucial requirement for realizing the spin-ice state—can be broken by means of high magnetic fields. For the case of the well-established classical spin-ice compound Ho2Ti2O7 the magnetization exceeds the angle-dependent saturation value of the Ising limit using ultrahigh fields up to 120 T. However, even under such extreme magnetic fields full saturation cannot be achieved. Crystal-electric-field calculations reveal that a level crossing for two of the four ion positions leads to magnetization steps at 55 and 100 T. In addition, we show that by using a field sweep rate in the range of the spin-relaxation time the dynamics of the spin system can be probed. Exclusively at 25 ns/T, a new peak of the susceptibility appears around 2 T. We argue, this signals the crossover between spin-ice and polarized correlations.

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Publ.-Id: 28922 - Permalink


Electronic band structure and proximity to magnetic ordering in the chiral cubic compound CrGe
Klotz, J.; Götze, K.; Förster, T.; Bruin, J. A. N.; Wosnitza, J.; Weber, K.; Schmidt, M.; Schnelle, W.; Geibel, C.; Rößler, U. K.; Rosner, H.;
CrGe belongs to the family of cubic B20 intermetallics. From experimental investigations by susceptibility and de Haas-van Alphen (dHvA) measurements and from calculations of its electronic band structure by densityfunctional theory (DFT), CrGe is found to form a metallic paramagnetic ground state. Combining dHvA and DFT data, a detailed picture of the Fermi surface of CrGe is provided. The proximity to a magnetic longrange ordering in CrGe is suggested from a prominent thermal magnetic susceptibility. The possibility to induce magnetic long-range order in CrGe is discussed based on calculated properties for CrGe substituting Ge by As or Sn, and from a comparison with MnGe and the alloy series Cr1−xMnxGe. Owing to the noncentrosymmetric and nonsymmorphic crystal structure of CrGe, in absence of broken time reversal symmetry, its band structure is marked by forced nodal lines at the Fermi edge. Moreover, this material hosts degenerate unconventional electronic quasiparticles. In particular, CrGe exhibits a sixfold degeneracy of fermions crossing within about 5 meV of the Fermi energy at the R point of the Brillouin zone.

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Publ.-Id: 28921 - Permalink


Magnetic phase diagram and crystal-field effects in the kagome-lattice antiferromagnet U3Ru4Al12
Gorbunov, D. I.; Ishii, I.; Nomura, T.; Henriques, M. S.; Andreev, A. V.; Uhlarz, M.; Suzuki, T.; Zherlitsyn, S.; Wosnitza, J.;
We report on the magnetic phase diagram of the distorted kagome-lattice antiferromagnet U3Ru4Al12 determined through measurements of magnetic and elastic properties. For field applied along the [100] and [120] axes of the hexagonal crystal structure, we find pronounced anomalies in the magnetization and elastic moduli that signal the existence of unknown magnetic phases. Our crystal-electric-field (CEF) analysis evidences interlevel quadrupolar interactions between the ground-state singlet and the first excited doublet. These interactions lead to a large softening of the shear elastic modulus C44. The large number of phases and pronounced elastic
softening suggest that geometric frustrations and CEF effects play an important role in the physical properties of U3Ru4Al12.

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Publ.-Id: 28920 - Permalink


U2Ni2Sn and the origin of magnetic anisotropy in uranium compounds
Maskova, S.; Andreev, A. V.; Skourski, Y.; Yasin, S.; Gorbunov, D. I.; Zherlitsyn, S.; Nakotte, H.; Kothapalli, K.; Nasreen, F.; Cupp, C.; Cao, H. B.; Kolomiets, A.; Havela, L.;
U2Ni2Sn is a member of a large family of intermetallic compounds with the tetragonal Mo2FeB2 crystal structure. It orders antiferromagnetically at 25 K with propagation vector q = (0, 0, 1/2 ). Magnetization, magnetoacoustic, and neutron-diffraction experiments on a single crystal provide evidence that the uranium moments align parallel to the c axis with the anisotropy energy of ≈170 K, indicating that U2Ni2Sn can be classified as an Ising system. The results are at variance with previous studies on polycrystals, which indicated different magnetic structure, and which were incompatible with the 5 f -5 f two-ion anisotropy model dominant in most U band systems. High-field magnetization studies exhibit a weak linear response for fields along the basal plane up to the highest field applied (60 T), while the c-axis magnetization curve exhibits three metamagnetic transitions at approximately 30, 39, and 50 T. The U magnetic moments of 0.87μB, the low magnetic entropy, and the enhanced Sommerfeld coefficient γ = 187 mJ/mol f.u.K2 suggest that U2Ni2Sn can be classified as an itinerant antiferromagnet with strong electron-electron correlations.

Publ.-Id: 28919 - Permalink


Depth and Dissolved Organic Carbon Shape Microbial Communities in Surface Influenced but Not Ancient Saline Terrestrial Aquifers
Lopez-Fernandez, M.; Åström, M.; Bertilsson, S.; Dopson, M.;
The continental deep biosphere is suggested to contain a substantial fraction of the earth’s total biomass and microorganisms inhabiting this environment likely have a substantial impact on biogeochemical cycles. However, the deep microbial community is still largely unknown and can be influenced by parameters such as temperature, pressure, water residence times, and chemistry of the waters. In this study, 21 boreholes representing a range of deep continental groundwaters from the Äspö Hard Rock Laboratory were subjected to high-throughput 16S rRNA gene sequencing to characterize how the different water types influence the microbial communities. Geochemical parameters showed the stability of the waters and allowed their classification into three groups. These were (i) waters influenced by infiltration from the Baltic Sea with a “modern marine (MM)” signature, (ii) a “thoroughly mixed (TM)” water containing groundwaters of several origins, and (iii) deep “old saline (OS)” waters. Decreasing microbial cell numbers positively correlated with depth. In addition, there was a stronger positive correlation between increased cell numbers and dissolved organic carbon for the MM compared to the OS waters. This supported that the MM waters depend on organic carbon infiltration from the Baltic Sea while the ancient saline waters were fed by “geogases” such as carbon dioxide and hydrogen. The 16S rRNA gene relative abundance of the studied groundwaters revealed different microbial community compositions. Interestingly, the TM water showed the highest dissimilarity compared to the other two water types, potentially due to the several contrasting water types contributing to this groundwater. The main identified microbial phyla in the groundwaters were Gammaproteobacteria, unclassified sequences, Campylobacterota (formerly Epsilonproteobacteria), Patescibacteria, Deltaproteobacteria, and Alphaproteobacteria. Many of these taxa are suggested to mediate ferric iron and nitrate reduction, especially in the MM waters. This indicated that nitrate reduction may be a neglected but important process in the deep continental biosphere. In addition to the high number of unclassified sequences, almost 50% of the identified phyla were archaeal or bacterial candidate phyla. The percentage of unknown and candidate phyla increased with depth, pointing to the importance and necessity of further studies to characterize deep biosphere microbial populations.
Keywords: 16S rRNA gene, amplicon sequencing, deep subsurface, groundwaters, chemistry, microbial diversity

Publ.-Id: 28915 - Permalink


Microbial Community and Metabolic Activity in Thiocyanate Degrading Low Temperature Microbial Fuel Cells
Ni, G.; Canizales, S.; Broman, E.; Simone, D.; Palwai, V. R.; Lundin, D.; Lopez-Fernandez, M.; Sleutels, T.; Dopson, M.;
Thiocyanate is a toxic compound produced by the mining and metallurgy industries that needs to be remediated prior to its release into the environment. If the industry is situated at high altitudes or near the poles, economic factors require a low temperature treatment process. Microbial fuel cells are a developing technology that have the benefits of both removing such toxic compounds while recovering electrical energy. In this study, simultaneous thiocyanate degradation and electrical current generation was demonstrated and it was suggested that extracellular electron transfer to the anode occurred. Investigation of the microbial community by 16S rRNA metatranscriptome reads supported that the anode attached and planktonic anolyte consortia were dominated by a Thiobacillus-like population. Metatranscriptomic sequencing also suggested thiocyanate degradation primarily occurred via the ‘cyanate’ degradation pathway. The generated sulfide was metabolized via sulfite and ultimately to sulfate mediated by reverse dissimilatory sulfite reductase, APS reductase, and sulfate adenylyltransferase and the released electrons were potentially transferred to the anode via soluble electron shuttles. Finally, the ammonium from thiocyanate degradation was assimilated to glutamate as nitrogen source and carbon dioxide was fixed as carbon source. This study is one of the first to demonstrate a low temperature inorganic sulfur utilizing microbial fuel cell and the first to provide evidence for pathways of thiocyanate degradation coupled to electron transfer.
Keywords: MFC, thiocyanate degradation, extracellular electron transfer, low temperature, metatranscriptomics

Publ.-Id: 28914 - Permalink


Metatranscriptomes Reveal That All Three Domains of Life Are Active but Are Dominated by Bacteria in the Fennoscandian Crystalline Granitic Continental Deep Biosphere
Lopez-Fernandez, M.; Simone, D.; Wu, X.; Soler, L.; Nilsson, E.; Holmfeldt, K.; Lantz, H.; Bertilsson, S.; Dopson, M.;
ABSTRACT The continental subsurface is suggested to contain a significant part of the earth’s total biomass. However, due to the difficulty of sampling, the deep subsurface is still one of the least understood ecosystems. Therefore, microorganisms inhabiting this environment might profoundly influence the global nutrient and energy cycles. In this study, in situ fixed RNA transcripts from two deep continental groundwaters from the Äspö Hard Rock Laboratory (a Baltic Sea-influenced water with a residence time of < 20 years, defined as “modern marine,” and an “old saline” groundwater with a residence time of thousands of years) were subjected to metatranscriptome sequencing. Although small subunit (SSU) rRNA gene and mRNA transcripts aligned to all three domains of life, supporting activity within these community subsets, the data also suggested that the groundwaters were dominated by bacteria. Many of the SSU rRNA transcripts grouped within newly described candidate phyla or could not be mapped to known branches on the tree of life, suggesting that a large portion of the active biota in the deep biosphere remains unexplored.
Despite the extremely oligotrophic conditions, mRNA transcripts revealed a diverse range of metabolic strategies that were carried out by multiple taxa in the modern marine water that is fed by organic carbon from the surface. In contrast, the carbon dioxide- and hydrogen-fed old saline water with a residence time of thousands of years predominantly showed the potential to carry out translation. This suggested these cells were active, but waiting until an energy source episodically becomes available.
IMPORTANCE A newly designed sampling apparatus was used to fix RNA under in situ conditions in the deep continental biosphere and benchmarks a strategy for deep biosphere metatranscriptomic sequencing. This apparatus enabled the identification of active community members and the processes they carry out in this extremely oligotrophic environment. This work presents for the first time evidence of eukaryotic, archaeal, and bacterial activity in two deep subsurface crystalline rock groundwaters from the Äspö Hard Rock Laboratory with different depths and geochemical characteristics. The findings highlight differences between organic carbon fed shallow communities and carbon dioxide- and hydrogen-fed old saline waters. In addition, the data reveal a large portion of uncharacterized microorganisms, as well as the important role of candidate phyla in the deep biosphere, but also the disparity in microbial diversity when using standard microbial 16S rRNA gene amplification versus the large unknown portion of the community identified with unbiased metatranscriptomes.
Keywords: metatranscriptomes, mRNA, rRNA, deep biosphere, groundwaters

Publ.-Id: 28913 - Permalink


Investigation of viable taxa in the deep terrestrial biosphere suggests high rates of nutrient recycling
Lopez-Fernandez, M.; Broman, E.; Turner, S.; Wu, X.; Bertilsson, S.; Dopson, M.;
The deep biosphere is the largest ‘bioreactor’ on earth, and microbes inhabiting this biome profoundly influence global nutrient and energy cycles. An important question for deep biosphere microbiology is whether or not specific populations are viable. To address this, we used quantitative PCR and high throughput 16S rRNA gene sequencing of total and viable cells (i.e. with an intact cellular membrane) from three groundwaters with different ages and chemical constituents. There were no statistically significant differences in 16S rRNA gene abundances and microbial diversity between total and viable communities. This suggests that populations were adapted to prevailing oligotrophic conditions and that non-viable cells are rapidly degraded and recycled into new biomass. With higher concentrations of organic carbon, the modern marine and undefined mixed waters hosted a community with a larger range of predicted growth strategies than the ultra-oligotrophic old saline water. These strategies included fermentative and potentially symbiotic lifestyles by candidate phyla that typically have streamlined genomes. In contrast, the old saline waters had more 16S rRNA gene sequences in previously cultured lineages able to oxidize hydrogen and fix carbon dioxide. This matches the paradigm of a hydrogen and carbon dioxide-fed chemolithoautotrophic deep biosphere.
Keywords: 16S rRNA gene; deep subsurface; fracture groundwaters; propidium monoazide; viable cells; candidate phyla radiation

Publ.-Id: 28912 - Permalink


Effect of insertion layer on electrode properties in magnetic tunnel junctions with a zero-moment half-metal
Titova, A.; Fowley, C.; Clifford, E.; Lau, Y.-C.; Borisov, K.; Betto, D.; Atcheson, G.; Hübner, R.; Xu, C.; Stamenov, P.; Coey, M.; Rode, K.; Lindner, J.; Fassbender, J.; Deac, A. M.;
Due to its negligible spontaneous magnetization, high spin polarization and giant perpendicular magnetic anisotropy, Mn₂RuₓGa (MRG) is an ideal candidate as an oscillating layer in THz spin-transfer-torque nano-oscillators. Here, the effect of ultrathin Al and Ta diffusion barriers between MRG and MgO in perpendicular magnetic tunnel junctions is investigated and compared to devices with a bare MRG/MgO interface. Both the compensation temperature, Tcomp, of the electrode and the tunneling magnetoresistance (TMR) of the device are highly sensitive to the choice and thickness of the insertion layer used. High-resolution transmission electron microscopy, as well as analysis of the TMR, its bias dependence, and the resistance-area product allow us to compare the devices from a structural and electrical point of view. Al insertion leads to the formation of thicker effective barriers and gives the highest TMR, at the cost of a reduced Tcomp. Ta is the superior diffusion barrier which retains Tcomp, however, it also leads to a much lower TMR on account of the short spin diffusion length which reduces the tunneling spin polarization. The study shows that fine engineering of the Mn₂RuₓGa/barrier interface to improve the TMR amplitude is feasible.
Keywords: Tunneling Magnetoresistance, Half-Metal, Mn-based alloys, MRAM, Spin Polarisation, Heusler alloy, Ferrimagnetic, Perpendicular Magnetic Anisotropy

Publ.-Id: 28906 - Permalink


Equiatomic quinary rare-earth rich amorphous ribbons with excellent magnetocaloric performance
Li, L.; Xu, C.ORC; Yuan, Y.; Zhou, S.
The glass forming ability, microstructure, magnetism and magnetocaloric effect (MCE) in two quinary rare-earth rich amorphous ribbons of Tm20Ho20Gd20Co20Ni20 and Tm20Ho20Gd20Co20Cu20 are reported. Both amorphous ribbons exhibit excellent glass forming ability and a table-like MCE. In addition to large magnetic entropy change of ∼14.0 J/kg-K, an extremely high refrigerant capacity of ∼790 J/kg are achieved which can almost cover the temperature range from liquid hydrogen to liquid nitrogen for the magnetic field change of 0–7 T for both ribbons. Therefore, the quinary rare-earth rich amorphous ribbons can be proposed as a new class of promising magnetic refrigeration materials.

Publ.-Id: 28905 - Permalink


Annual Report 2018 - Institute of Resource Ecology
Stumpf, T.; Foerstendorf, H.ORC; Bok, F.; Richter, A.
Annual Report 2018 of the scientific activities of the Institute of Resource Ecology of the Helmholtz-Zentrum Dresden-Rossendorf
  • Open Access LogoWissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-096 2019
    ISSN: 2191-8708

Publ.-Id: 28898 - Permalink


Coordination chemistry of f-block metal ions with ligands bearing bio-relevant functional groups
Götzke, L.; Schaper, G.; März, J.ORC; Kaden, P.ORC; Huittinen, N.ORC; Stumpf, T.; Kammerlander, K. K. K.; Brunner, E.; Hahn, P.; Mehnert, A.; Kersting, B.; Henle, T.; Lindoy, L. F.; Zanoni, G.; Weigand, J. J.
Over recent decades there has been a great deal of interest and associated research into aspects of the f-block (lanthanide and actinide) metal chemistry of naturally-occurring ligands, such as proteins, peptides, porphyrins and related tetraaza derivatives as well as synthetically modified natural ligands and solely synthetic ligand systems incorporating bio-relevant functional groups. In this review, we present a wide-ranging overview of published work spanning the above areas, with emphasis on selected biological, medical and environmental aspects. Systems capable of discriminating between metal ions from within, or between, the lanthanide and actinide groups are also discussed including the design and synthesis of biomimetic radionuclide chelators and radionuclide decorporation agents as well as solid adsorbent materials for the uptake of radionuclides from the environment and elsewhere. Thus, the interaction of the f-group elements with a range of biopolymers, including systems based on cellulose, chitin, chitosan, humic substances as well as a range of synthetic model systems is also presented. Other applications include the synthesis of new luminescent materials, including luminescent probes and luminescent metal coordination polymers exhibiting unusual photophysical properties as well as systems showing potential for use in the development of new MRI imaging agents.
Keywords: Lanthanides Actinides Maillard products Siderophores Calix[4]arenes Porphyrins Cellulose Chitin Chitosan Humic substances Peptides Proteins

Publ.-Id: 28895 - Permalink


Two-Dimensional Kagome Lattices Made of Hetero Triangulenes Are Dirac Semimetals or Single-Band Semiconductors
Jing, Y.; Heine, T.ORC
Here we discuss, based on first-principles calculations, two-dimensional (2D) kagome lattices composed of polymerized heterotriangulene units, planar molecules with D3h point group containing a B, C, or N center atom and CH2, O, or CO bridges. We explore the design principles for a functional lattice made of 2D polymers, which involves control of π-conjugation and electronic structure of the knots. The former is achieved by the chemical potential of the bridge groups, while the latter is controlled by the heteroatom. The resulting 2D kagome polymers have a characteristic electronic structure with a Dirac band sandwiched by two flat bands and are either Dirac semimetals (C center), or single-band semiconductors—materials with either exclusively electrons (B center) or holes (N center) as charge carriers of very high mobility, reaching values of up to ∼8 × 103 cm2 V–1 s–1, which is comparable to crystalline silicon.
Keywords: DFT, kagome, 2D polymers, 2D COFs

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  • Secondary publication expected from 30.11.2020

Publ.-Id: 28890 - Permalink


Assessing robustness of radiomic features by image perturbation
Zwanenburg, A.; Leger, S.; Agolli, L.; Pilz, K.; Troost, E.; Richter, C.; Löck, S.;
Image features need to be robust against differences in positioning, acquisition and segmentation to ensure reproducibility. Radiomic models that only include robust features can be used to analyse new images, whereas models with non-robust features may fail to predict the outcome of interest accurately. Test-retest imaging is recommended to assess robustness, but may not be available for the phenotype of interest. We therefore investigated 18 combinations of image perturbations to determine feature robustness, based on noise addition (N), translation (T), rotation (R), volume growth/shrinkage (V) and supervoxel-based contour randomisation (C). Test-retest and perturbation robustness were compared for combined total of 4032 morphological, statistical and texture features that were computed from the gross tumour volume in two cohorts with computed tomography imaging: I) 31 non-small-cell lung cancer (NSCLC) patients; II): 19 head-and-neck squamous cell carcinoma (HNSCC) patients. Robustness was determined using the 95% confidence interval (CI) of the intraclass correlation coefficient (1, 1). Features with CI >= 0:90 were considered robust. The NTCV, TCV, RNCV and RCV perturbation chain produced similar results and identified the fewest false positive robust features (NSCLC: 0.2-0.9%; HNSCC: 1.7-1.9%). Thus, these perturbation chains may be used as an alternative to test-retest imaging to assess feature robustness.

Publ.-Id: 28889 - Permalink


Testing halophilic bacteria for their potential as pyrite biodepressants in Cu-Mo bioflotation
Luque Consuegra, G.;
Presentation outlining work up to June 2018 in the screening of halophilic bacteria as pyrite biodepressants in Cu-Mo bioflotation processes delivered in the BHT conference in TUBAF, Freiberg.
Keywords: Bioflotation, Pyrite, Halophilic bacteria, Adhesion, M.A.T.H
  • Lecture (Conference)
    BHT – Freiberger Universitätsforum, 08.06.2018, Freiberg, Deutschland

Publ.-Id: 28884 - Permalink


Characterization of Continuous Wave Laser-Induced ThermalGradients in Magnetic Tunnel Junctions Integrated IntoMicroresonators via COMSOL Simulations
Cansever, H.; Lindner, J.; Huebner, T.; Niesen, A.; Reiss, G.; Fassbender, J.; Deac, A. M.;
Spin caloritronics investigates static and dynamic effects on magnetic structures due to spin-currents generated by thermalgradients. Here, we present COMSOL simulation results using a 2-D heat transfer module applied to Co2FeAl/MgO/CoFeB magnetictunnel junctions (MTJs) integrated into microcavity resonators. Microresonators are used in order to study the effects of temperaturegradients on single micro-/nano-objects. We find that the thermal conductivity of the insulating barrier (MgO) plays a crucialrole, influencing the overall temperature, as well as the thermal gradient over the barrier. Taking into account the microresonatorstructure around the MTJ, which is mainly made from copper, strongly affects the uniform heating of the overall stack. Nevertheless,the gradient over the barrier is relatively unaffected by the surrounding conditions. The simulation results provide insight intothe temperature profile of the whole structure and show how modifying the structure of the surrounding materials may tune andoptimize the thermal gradient magnitude and ultimately provide a path for quantifying spin-transfer torques induced by thermalgradients.
Keywords: COMSOL simulation, ferromagnetic resonance (FMR), magnetic tunnel junction (MTJ), microresonator

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  • Secondary publication expected from 05.02.2020

Publ.-Id: 28879 - Permalink


Fast-neutron-induced fission cross section of Pu(242) measured at the neutron time-of-flight facility nELBE
Kögler, T.ORC; Junghans, A. R.ORC; Beyer, R.ORC; Dietz, M.; Düllmann, C. E.ORC; Eberhardt, K.; Lorenz, C.; Müller, S. E.ORC; Nolte, R.; Reinhardt, T. P.; Schmidt, K.; Runke, J.; Schwengner, R.ORC; Takacs, M.; Vascon, A.; Wagner, A.ORC
The fast-neutron-induced fission cross section of ²⁴²Pu was measured at the neutron time-of-flight facility nELBE. A parallel-plate fission ionization chamber with novel, homogeneous, large-area ²⁴²Pu deposits on Si-wafer backings was used to determine this quantity relative to the IAEA neutron cross-section standard ²³²U(n, f ) in the energy range of 0.5 to 10 MeV. The number of target nuclei was determined from the measured spontaneous fission rate of ²⁴²Pu. This helps to reduce the influence of the fission fragment detection efficiency on the cross section. Neutron transport simulations performed with GEANT 4, MCNP 6, and FLUKA 2011 are used to correct the cross-section data for neutron scattering. In the reported energy range the systematic uncertainty is below 2.7% and on average the statistical uncertainty is 4.9%. The determined results show an agreement within 0.67(16)% to recently published data and a good accordance to current evaluated data sets.
Keywords: neutron-induced fission, plutonium, parallel plate fission ionization chambers, cross section measurements, neutron transport simulations, nuclear reactions, nucleon induced nuclear reactions, nELBE
Related publications
Fast-neutron-induced fission cross section of Pu(242) … (Id 28970) HZDR-primary research data are used by this publication

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Publ.-Id: 28878 - Permalink


Impact of radiation, systemic therapy and Treatment sequencing on survival of patients with melanoma brain metastases
Rauschenberga, R.; Bruns, J.; Brüttinga, J.; Daubner, D.; Lohaus, F.; Zimmer, L.; Forschner, A.; Zips, D.; Hassel, J. C.; Berking, C.; Kaehler, K. C.; Utikal, J.; Gutzmer, R.; Terheyden, P.; Meiss, F.; Rafei-Shamsabadi, D.; Kiecker, F.; Debus, D.; Dabrowski, E.; Arnold, A.; Garzarolli, M.; Kuske, M.; Beissert, S.; Löck, S.; Linn, J.; Troost, E. G. C.; Meier, F.;
Background
Combining stereotactic radiosurgery (SRS) and active systemic therapies (STs) achieved favourable survival outcomes in patients with melanoma brain metastases (MBMs) in retrospective analyses. However, several aspects of this Treatment strategy remain poorly understood. We Report on the Overall survival (OS) of patients with MBM treated with a combination of radiotherapy (RT) and ST as well as the Impact of the v-Raf murine sarcoma viral oncogene homolog B (BRAF)-V600 Mutation (BRAFmut) status, types of RT and ST and their sequence. Patients and methods Data of 208 patients treated with SRS or whole brain Radiation therapy (WBRT) and either immunotherapy (IT) or targeted therapy (TT) within a 6-week- interval to RT were analysed retrospectively. OS was calculated from RT to death or last follow-up. Univariate- and multivariate Cox proportional hazard analyses were performed to determine prognostic Features associated with OS.
Results
The median follow-up was 7.3 months. 139 patients received IT, 67 received TT and 2 received IT and TT within 6 weeks to RT (WBRT 45%; SRS 55%). One-year Kaplan-Meier OS rates were 69%, 65%, 33% and 18% (P < .001) for SRS with IT, SRS with TT, WBRT with IT and WBRT with TT, respectively. Patients with a BRAF mut receiving IT combined with RT experienced higher OS rates (88%, 65%, 50% and 18%). TT following RT or started before and continued thereafter was associated with improved median OS compared with to TT solely before RT (12.2 [95% confidence interval {CI} 9.3–15.1]; 9.8 [95% CI 6.9–12.6] versus 5.1 [95% CI 2.7–7.5]; P = .03).
Conclusion
SRS and IT achieved the highest OS rates. A BRAFmut appears to be a favourable prognostic factor for OS. For the combination of RT and TT, the sequence appears to be crucial. Combinations of WBRT and ST achieved unprecedentedly high OS rates and Warrant further studies.
Keywords: Melanoma; Brain metastases; Stereotactic radiosurgery; Whole brain Radiation therapy; Immunotherapies; Targeted therapy; Immune checkpoint inhibitors; BRAF inhibitors

Publ.-Id: 28875 - Permalink


Carboranyl Analogues of Celecoxib with Potent Cytostatic Activity against Human Melanoma and Colon Cancer Cell Lines
Buzharevski, A.; Paskas, S.; Sárosi, M. B.; Laube, M.; Lönnecke, P.; Neumann, W.; Mijatovic, S.; Maksimovic-Ivanic, D.; Pietzsch, J.ORC; Hey-Hawkins, E.
Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most common way of treating inflammatory disorders. Their widespread use helped reveal their other modes of action as pharmaceuticals, such as a profound effect on various cancers. Celecoxib has proven to be a very prominent member of this group with cytostatic activities. On the other hand, the highly dynamic field of drug design is constantly searching for new ways of modifying known structures to obtain more powerful and less harmful drugs. A very interesting development is the implementation of carboranes in pharmacologically active structures, mostly as phenyl mimetics. Herein we report the synthesis of three carborane-containing derivatives of the COX-2-selective NSAID celecoxib. The new compounds proved to have promising cytostatic potential against various melanoma and colorectal adenocarcinoma cell lines. Inhibited proliferation accompanied by caspase-independent apoptotic cell death was found to be the main cause of decreased cell viability upon treatment with the most efficient celecoxib analogue, 3 b (4-[5-(1,7-dicarba-closo-dodecaboranyl)-3-trifluoromethyl-1H-pyrazol-1-yl]-1-methylsulfonylbenzene).
Keywords: cancer; carboranes; celecoxib; cytotoxicity; drug discovery

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Publ.-Id: 28874 - Permalink


Simulation of the Radiation Field at the University Proton Therapy Dresden (UPTD)
Lutz, B.; Swanson, R.; Fiedler, F.; Enghardt, W.;
Radiation therapy is one of the most used treatment modalities of cancer. While most patients receive photon-therapy, a growing number of patients are treated with particles, mainly protons. Protons offers a more localised dose deposition compared to photon-therapy. This allows to reduce the dose that is applied by the primary beam to the healthy tissue outside the target volume. At the same time, the use of protons leads to a change in the composition of the radiation field, when compared to photons. For example, the out-of-field dose is dominated by secondary neutrons. Additionally, the radiation quality of protons is a function of energy. Therefore, the biological effect depends not only on the physical dose, but also on the linear energy transfer (LET). The neutron field and the LET, like other scientifically interesting quantities, are challenging to measure experimentally. Hence, a simulation that can reproduce the radiation field of a radiation treatment facility is of great value for the study of various aspects of proton therapy.
This work describes the simulation of the University Proton Therapy Dresden (UPTD) beam delivery system and treatment room.
Keywords: simulation, proton therapy, Geant4, TOPAS, double scattering
  • Lecture (Conference)
    EURADOS Annual Meeting 2019, 11.-14.02.2019, Lodz, Poland

Publ.-Id: 28873 - Permalink


Fluorine-18 labeling of S100 proteins for small animal positron emission tomography
Laube, M.; Kniess, T.; Neuber, C.; Haase-Kohn, C.; Pietzsch, J.ORC
The interaction of S100 proteins (S100s), a multigenic family of Ca2+-binding and Ca2+-modulated proteins, with pattern recognition receptors, e.g., Toll-like receptors (TLRs), the receptor for advanced glycation end products (RAGE), or scavenger receptors (SR), is hypothesized to be of high relevance in the pathogenesis of various diseases. This includes chronic inflammatory conditions, atherosclerosis, cardiomyopathies, neurodegeneration, and progression of cancers. However, data concerning the role of circulating S100s in these pathologies are scarce. One reason for this is the shortage of suitable radiolabeling methods for direct assessment of the metabolic fate of circulating S100s in vivo. We report a radiotracer approach using radiolabeling of recombinant human S100s with the positron emitter fluorine-18 (18F) by conjugation with N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB). The methodological radiochemical part focuses on an optimized and automated synthesis of [18F]SFB comprising HPLC purification to achieve higher chemical purity. The respective radioligands, [18F]fluorobenzoylated S100s ([18F]FB-S100s), were obtained with appropriate radiochemical purities, yields, and effective molar activities. Biological applications comprise cell and tissue binding experiments in vitro, biodistribution and metabolite studies in rodents in vivo/ex vivo, and dynamic positron emission tomography studies using dedicated small animal PET systems. Radiolabeling of S100s with 18F and, particularly, the use of small animal PET provide novel probes to delineate both their metabolic fate and the functional expression of their specific receptors under normal and pathophysiological conditions in rodent models of disease.
Keywords: Bolton-Hunter-type reagent; in vivo imaging; radiopharmacological characterization; 18F building block; module-assisted radiosynthesis; S100 proteins; calcium; EF-hand

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  • Secondary publication expected from 02.02.2020

Publ.-Id: 28872 - Permalink


The Inverse Trans Effect in Uranium complexes containing N-heterocyclic Carbenes
Köhler, L.; März, J.; Patzschke, M.; Kloditz, R.; Stumpf, T.;
Aim of this work was to investigate the inverse trans influence (ITI) in uranium complexes containing soft-donor ligands. Uranium(IV) and (V) complexes were synthesized by using the N-heterocylic carbene ligand iPrIm (L¹ ) and lithium bis(trimethylsilyl)amide (TMSA) as a base. The structural characterization by SC-XRD and geometry optimization of the resulting compounds [U(IV)(L¹ )₂(TMSA)Cl₃] (1) and (HL¹ )₂ [U(V)(TMSI)Cl₅] (2) (TMSI = trimethylsilylimide) confirmed the occurrence of an inverse trans influence (ITI) by means of the silylamido- or silylimido ligand.
Keywords: inverse trans influence, ITI, uranium complex, actinides
  • Lecture (others)
    Bilaterales Treffen mit AK Roesky (KIT), 10.-11.01.2019, Karlsruhe, Deutschland

Publ.-Id: 28869 - Permalink


Reversible adiabatic temperature change in the shape memory Heusler alloy NiMn0.8Ga: An effect of structural compatibility
Devi, P.; Ghorbani Zavareh, M.; Salazar Mejia, C.; Hofmann, K.; Albert, B.; Felser, C.; Nicklas, M.; Singh, S.;
The large magnetocaloric effect (MCE) observed in Ni-Mn based shape memory Heusler alloys put them forward to use in magnetic refrigeration technology. It is associated with a first-order magnetostructural (martensitic) phase transition.We conducted a comprehensive study of the MCE for the off-stoichiometric Heusler alloy Ni2.2Mn0.8Ga in the vicinity of its first-order magnetostructural phase transition. We found a reversible MCE under repeated magnetic field cycles. The reversible behavior can be attributed to the small thermal hysteresis of the martensitic phase transition. Based on the analysis of our detailed temperature dependent x-ray diffraction data, we demonstrate the geometric compatibility of the cubic austenite and tetragonal martensite phases. This finding directly relates the reversible MCE behavior to an improved geometric compatibility condition between cubic austenite and tetragonal martensite phases. The approach will help to design shape memory Heusler alloys with a large reversible MCE taking advantage of the first-order martensitic phase transition.

Publ.-Id: 28868 - Permalink


Focusing of multi-MeV, subnanosecond proton bunches from a laser-driven source
Jahn, D.; Schumacher, D.; Brabetz, C.; Kroll, F.; Brack, F.-E.; Ding, J.; Leonhardt, R.; Semmler, I.; Blazevic, A.; Schramm, U.; Roth, M.;
We report on our latest transverse focusing results of subnanosecond proton bunches achieved with a laser-driven multi-MeV ion beamline. In the frame of the LIGHT collaboration, a target normal sheath acceleration (TNSA) source based 6 m long beamline was installed. In the past years, the laser-driven proton beam was transported and shaped by this beamline. The particle beam is collimated with a pulsed high-field solenoid and rotated in longitudinal phase space with a radio-frequency cavity which leads to an energy compression with an energy spread of (2.7 +/- 1.7)% (Delta E/E-0 at FWHM) or a time compression to the subnanosecond regime. Highest peak intensities in the subnanosecond regime open up an interesting field for several applications, e.g., proton imaging, as injectors in conventional accelerators or precise stopping power measurements in a plasma. We report on achieving highest peak intensities using an installed second solenoid as a final focusing system in our beamline to achieve small focal spot sizes. We measured a focal spot size of 1.1 x 1.2 mm leading to 5.8 x 10(19) protons per s cm(2) at a central energy bin of (9.55 +/- 0.25) MeV, which can be combined with a bunch duration below 500 ps at FWHM.

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Publ.-Id: 28866 - Permalink


4He irradiation of zircon, ZrSiO4, using a micro-patterned, Si-based energy filter
Nasdala, L.; Akhmadaliev, S.; Chanmuang N., C.; Zowalla, A.; Csato, C.; Rüb, M.;
The quantitative evaluation of alpha-particle damage in the mineral zircon, ZrSiO4, using 4He irradiation experiments is difficult because the vast majority of atomic knock-ons in the target are concentrated in a narrow depth range near the ends of the He-ion trajectories. Here we present a new concept to overcome this problem, namely, tailoring the depth profile of damage by means of a micromechanically fabricated “energy filter”. Lamellae of 1.5 μm thickness, prepared from ZrSiO4 using the focused-ion-beam technique, were subjected to irradiation with 8.8 MeV 4He ions. Five irradiations with ion fluences in the range 2.5 × 1015–1 × 1017 cm-2 have resulted in mild to severe damage, as monitored by the broadening and downshift of SiO4-stretching Raman bands. Our results may provide a means for quantifying the contribution of alpha particles to the total self-irradiation damage in zircon.
Keywords: Radiation damage, Helium irradiation, Energy filter, Focused ion beam, Raman spectroscopy

Publ.-Id: 28865 - Permalink


Software in the context of luminescence dating: status, concepts and suggestions exemplified by the R package Luminescence
Kreutzer, S.; Burow, C.; Dietze, D.; Fuchs, M. C.; Fischer, M.; Schmidt, C.;
The relevance of luminescence dating is re- flected by the steadily growing quantity of published data. At the same time, the amount of data available for analysis has increased due to technological and methodological advances. Routinely, luminescence data are analysed using a mixture of commercially available soft- ware, self-written tools and specific solutions. Based on a luminescence dating literature screening we show how rarely articles report on the software used for the data analysis and we discuss potential problems arising from this. We explore the growing importance of the statistical programming language R in general and especially its reflection in recent software developments in the context of lu- minescence dating. Specifically, for the R package ‘Luminescence’ we show how the transparency, flexibility and reliability of tools used for the data analysis have been improved. We finally advocate for more transparency if unvalidated software solutions are used and we emphasise that more attention should be paid to the tools used for analysing the data.
Keywords: R, Software, Luminescence dating, Data analysis
  • Open Access LogoAncient TL 35(2017)2, 1-11

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Publ.-Id: 28863 - Permalink


The Need for Multi-Source, Multi-Scale Hyperspectral Imaging to Boost Non-Invasive Mineral Exploration
Gloaguen, R.; Ghamisi, P.; Lorenz, S.; Kirsch, M.; Zimmermann, R.; Booysen, R.; Andreani, L.; Jackisch, R.; Hermann, E.; Tusa, L.; Unger, G.; Contreras, C.; Khodadadzadeh, M.; Fuchs, M.;
The high demand for raw materials in our post-industrial societies contrasts the increasing difficulties to find new mineral deposits. In Europe, accessible and high-grade deposits are mostly exhausted or currently mined. Hence, future exploration must focus on the remaining, more remote locations or penetrate much deeper into the Earth's crust. Sustaining mining activities in Europe would allow the development of key technologies but also sustainable and ethical production of technological metals. Thus, we suggest to focus research on advances in multi-scale and multi-sensor remote sensing-based Earth integration techniques. The scale should range from satellite to air- and drone-borne systems and include ground validation. Multi-sensor downscaling methods involving SAR and optical data are particularly promising. We demonstrate that the integration with other sensors and/or measures such as geophysical/geochemical data as well as non-conventional remote sensing features such as textures and geometries are of interest. Thus, ultimately, our objective is to boost the competitiveness, growth, sustainability and attractiveness of the raw material sector in Europe. While we focus on the raw material sector as it is currently of strategic importance, the required methods are transferable to most environmental studies.
Keywords: Hyperspectral Imaging, Mineral Exploration
  • Open Access LogoContribution to proceedings
    IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 22.-27.09.2018, Valencia, Spain
    Proceedings of IGARSS 2018

Publ.-Id: 28859 - Permalink


Heavy Metal Binding Peptides – Design and Construction of new Biosorbents
Braun, R.ORC; Schönberger, N.; Bachmann, S.; Matys, S.ORC; Lederer, F.ORC; Pollmann, K.ORC
Heavy metal contaminations in both industrial and environmental waters are widely occurring. However, removal is both challenging and cost-intensive. In this study, we identified metal-binding peptide sequences using phage surface display (PSD). Fusion proteins with PSD-derived sequences were construced for further recombinant production, future scale-up and as alternative to chemical synthesis. The construction of the fusion proteins included usage of inteins and affinity tags for simplified expression and purification. Quartz crystal microbalance with dissipation monitoring (QCM-D) was used for further characterization of the peptide-metal interaction. The system developed in this study provides metal-binding peptides with high specificity and sensitivity. Being biodegradable, the constructed peptides can be used in multiple applications. The identified motifs can furthermore provide a deeper understanding of peptide-metal interaction, leading to the discovery of novel metal-interacting biomolecules and better prediction of involved amino acids.
  • Poster
    8th Peptide Engineering Meeting, 08.-10.11.2018, Berlin, Deutschland

Publ.-Id: 28858 - Permalink


Multivariate Data Assimilation for Resource Model Updating
Prior, A.; Benndorf, J.; Tolosana-Delgado, R.; van den Boogaart, K. G.;
This is just a presentation in the COSMO Day. I did not submit an abstract since I was invited speaker
  • Invited lecture (Conferences)
    COSMO Day 2018, 05.07.2018, Montreal, Canada

Publ.-Id: 28856 - Permalink


Multivariate Ensemble Based Sequential Update Of The Resource Model For Real Time Mine Settings
Prior, A.; Tolosana-Delgado, R.; Prior-Arce, A.;
Mining industry is continuously monitoring key performance indicators (KPI), and geo-metallurgical properties such as grade, fragmentation or tonnage and reconciling estimates to online capture production performance parameters. New technology is looking for monitoring also other properties as grain size.
Relevant information is obtained from sensors installed at different mining production process stages, as in a Block Evaluation or Schedule and Blending.
This study aims to develop an efficient updating framework based on Sequential Ensemble Filtering by using compositional data statistics that will be able to cope with the non-linearities of the system.
  • Poster
    POF Evaluation, 28.02.-02.03.2018, Dresden, Germany

Publ.-Id: 28855 - Permalink


Resource model updating for underground mining production settings
Prior, A.; Benndorf, J.; Mariz, C.;
This research is part of the European Union funded 'Real Time Mining' project, which aims to develop a new framework to reduce uncertainties during the extraction process in highly selective underground mining settings. A continuously self-updating resource/grade control model concept is presented and aims to improve the raw material quality control and process efficiency of any type of mining operation. Applications in underground mines include the improved control of different components of the mineralogy and geochemistry of the extracted ore utilizing available “big data” collected during production. The development of the methodology is based on two full scale case study, the copper-zinc mine Neves-Corvo in Portugal and Reiche-Zeche mine in Germany. These serve for both, for the definition of method requirements and also as a basis for defining a Virtual Asset Model (VAM), which serves for artificial sampling as benchmark for performance analysis. This contribution introduces to the updating concept, provides a brief description of the method, explains details of the test cases and demonstrates the value added by an illustrative case study.
Keywords: Underground Mining, Data Assimilation, Geostatistitcs
  • Open Access LogoContribution to proceedings
    REAL TIME MINING - Conference on Innovation on Raw Material Extraction Amsterdam 2017, 10.-11.10.2017, Amsterdam, The Netherlands

Publ.-Id: 28854 - Permalink


Tissue-type mapping of gliomas.
Raschke, F.; Barrick, T. R.; Jones, T.; Yang, G.; Ye, X.; Howe, F. A.;
PURPOSE:

To develop a statistical method of combining multimodal MRI (mMRI) of adult glial brain tumours to generate tissue heterogeneity maps that indicate tumour grade and infiltration margins.

MATERIALS AND METHODS:

We performed a retrospective analysis of mMRI from patients with histological diagnosis of glioma (n = 25). 1H Magnetic Resonance Spectroscopic Imaging (MRSI) was used to label regions of "pure" low- or high-grade tumour across image types. Normal brain and oedema characteristics were defined from healthy controls (n = 10) and brain metastasis patients (n = 10) respectively. Probability density distributions (PDD) for each tissue type were extracted from intensity normalised proton density and T2-weighted images, and p and q diffusion maps. Superpixel segmentation and Bayesian inference was used to produce whole-brain tissue-type maps.

RESULTS:

Total lesion volumes derived automatically from tissue-type maps correlated with those from manual delineation (p < 0.001, r = 0.87). Large high-grade volumes were determined in all grade III & IV (n = 16) tumours, in grade II gemistocytic rich astrocytomas (n = 3) and one astrocytoma with a histological diagnosis of grade II. For patients with known outcome (n = 20), patients with survival time < 2 years (3 grade II, 2 grade III and 10 grade IV) had a high-grade volume significantly greater than zero (Wilcoxon signed rank p < 0.0001) and also significantly greater high grade volume than the 5 grade II patients with survival >2 years (Mann Witney p = 0.0001). Regions classified from mMRI as oedema had non-tumour-like 1H MRS characteristics.

CONCLUSIONS:

1H MRSI can label tumour tissue types to enable development of a mMRI tissue type mapping algorithm, with potential to aid management of patients with glial tumours.
Keywords: Glioma; Magnetic resonance spectroscopy (MRS); Multimodal MRI; Nosologic imaging; Pattern recognition

Publ.-Id: 28845 - Permalink


Dynamics of the magnetoelastic phase transition and adiabatic temperature change in Mn1.3Fe0.7P0.5Si0.55
Fries, M.; Gottschall, T.; Scheibel, F.; Pfeuffer, L.; Skokov, K. P.; Skourski, I.; Acet, M.; Farle, M.; Wosnitza, J.; Gutfleisch, O.;
The adiabatic temperature change ΔTad of a Mn1.3Fe0.7P0.5Si0.55 Fe2P-type alloy was measured under different magnetic field-sweep rates from 0.93 Ts−1 to 2870 Ts−1. We find a field-sweep-rate independent magnetocaloric effect due to a partial alignment of magnetic moments in the paramagnetic region overlapping with the magnetocaloric effect of the first-order phase transition. Additionally, the first-order phase transition is not completed even in fields up to 20 T leading to a non-saturating behavior of ΔTad. Measurements in different pulsed fields reveal that the first-order phase transition cannot follow the fast field changes as previously assumed, resulting in a distinct field-dependent hysteresis in ΔTad.

Publ.-Id: 28844 - Permalink


Enzymes Immobilized on Carbon Nitride (C3N4) Cooperating with Metal Nanoparticles for Cascade Catalysis
Wang, Y.; Zhang, N.; Hübner, R.; Tan, D.; Löffler, M.; Facsko, S.; Zhang, E.; Ge, Y.; Qi, Z.; Wu, C.;
The exploration of effective platforms for immobilizing chemo- and biocatalysts to develop biohybrid catalysts is an attractive subject of practical interest. In this work, carbon nitride (C3N4) is used for the first time as a platform for the immobilization of metal catalyst (Pd nanoparticles) and biocatalyst (Candida antarctica lipase B, CalB) in a facile manner to prepare biohybrid catalyst. The optimal biohybrid catalyst inherits the intrinsic performance of both Pd nanoparticles and CalB, and shows high activity in the one-pot cascade reaction converting benzaldehyde to benzyl hexanoate at room temperature. With this proof of concept, it is expected that C3N4 can be utilized for immobilizing more types of chemo- and biocatalysts for perspective applications.
Keywords: biohybrid catalysts, CalB, carbon nitride, cascade reactions, Pd nanoparticles

Publ.-Id: 28842 - Permalink


Technical Note: Experimental verification of magnetic field-induced beam deflection and Bragg peak displacement for MR-integrated proton therapy.
Schellhammer, S. M.; Gantz, S.; Lühr, A.; Oborn, B. M.; Bussmann, M.; Hoffmann, A. L.;
Purpose: Given its sensitivity to anatomical variations, proton therapy is expected to benefit greatly from integration with magnetic resonance imaging for online anatomy monitoring during irradiation.
Such an integration raises several challenges, as both systems mutually interact. The proton beam will experience quasi-continuous energy loss and energy-dependent electromagnetic deflection at the same time, giving rise to a deflected beam trajectory and an altered dose distribution with a displaced Bragg peak. So far, these effects have only been predicted using Monte Carlo and analytical models, but no clear consensus has been reached and experimental benchmark data are lacking. We measured proton beam trajectories and Bragg peak displacement in a homogeneous phantom placed inside a magnetic field and compared them to simulations.
Methods: Planar dose distributions of proton pencil beams (80–180 MeV) traversing the field of a 0.95 T NdFeB permanent magnet while depositing energy in a PMMA slab phantom were measured using EBT3 radiochromic films and simulated using the Geant4 toolkit. Deflected beam trajectories and the Bragg peak displacement were extracted from the measured planar dose distributions and compared against the simulations.
Results: The lateral beam deflection was clearly visible on the EBT3 films and ranged from 1 to 10 mm for 80 to 180 MeV, respectively. Simulated and measured beam trajectories and Bragg peak displacement agreed within 0.8 mm for all studied proton energies.
Conclusions: These results prove that the magnetic field-induced Bragg peak displacement is both measurable and accurately predictable in a homogeneous phantom at 0.95 T, and allows Monte Carlo simulations to be used as gold standard for proton beam trajectory prediction in similar frameworks for MR-integrated proton therapy.
Keywords: magnetic field induced Bragg peak displacement, Monte Carlo simulation, MR guidance, proton dosimetry, proton therapy

Publ.-Id: 28841 - Permalink


SDF-1/CXCR4 expression is an independent negative prognostic biomarker in patients with head and neck cancer after primary radiochemotherapy
De-Colle, C.; Menegakis, A.; Mönnich, D.; Welz, S.; Boeke, S.; Sipos, B.; Fend, F.; Mauz, P. S.; Tinhofer, I.; Budach, V.; Abu, J. J.; Stuschke, M.; Balermpas, P.; Rödel, C.; Grosu, A. L.; Abdollahi, A.; Debus, J.; Belka, C.; Ganswindt, U.; Pigorsch, S.; Combs, S. E.; Lohaus, F.; Linge, A.; Krause, M.; Baumann, M.; Zips, D.;
Introduction: Preclinical and clinical data suggest that the chemokine pathway governed by SDF-1 and CXCR4 contributes to a resistant phenotype. This retrospective biomarker study aims to explore the specific prognostic value of SDF-1 and CXCR4 expression in locally advanced head and neck squamous cell carcinomas (HNSCC) treated with primary radiochemotherapy (RT-CT).
Material and methods: Biopsies from 141 HNSCC tumours of the oral cavity, oropharynx and hypopharynx were evaluated for SDF-1 and CXCR4 expression by immunofluorescence. SDF-1 and CXCR4 expression was correlated with clinico-pathological characteristics and outcome after RT-CT.
Results: Patients with tumours exhibiting overexpression of intracellular SDF-1 and CXCR4 have a higher risk for loco-regional relapse and a worse overall survival after RT-CT (multivariate analysis, hazard ratio 2.33, CI [1.18–4.62], p = 0.02 and hazard ratio 2.02, CI [1.13–3.59], p = 0.02, respectively). Similar results were observed when only the subgroup of HPV DNA negative patients were analysed (hazard ratio 2.23 and 2.16, p = 0.02 and p = 0.01, respectively).
Conclusions: Our data support the importance of SDF-1 and CXCR4 expression for loco-regional control and overall survival in HNSCC after primary radiochemotherapy. Prospective multivariate validation and further studies into CXCR4 inhibition to overcome radiation resistance are warranted.
Keywords: SDF-1 CXCR4 Head and neck cancer Prognostic Biomarker Primary radiochemotherapy

Publ.-Id: 28840 - Permalink


Improved effectiveness of stereotactic radiosurgery in large brain metastases by individualized isotoxic dose prescription: an in silico study
Zindler, J. D.; Schiffelers, J.; Lambin, P.; Hoffmann, A. L.;
Introduction In large brain metastases (BM) with a diameter of more than 2cm there is an increased risk of radionecrosis (RN) with standard stereotactic radiosurgery (SRS) dose prescription, while the normal tissue constraint is exceeded. The tumor control probability (TCP) with a single dose of 15Gy is only 42%. This in silico study tests the hypothesis that isotoxic dose prescription (IDP) can increase the therapeutic ratio (TCP/Risk of RN) of SRS in large BM.
Materials and methods A treatment-planning study with 8 perfectly spherical and 46 clinically realistic gross tumor volumes (GTV) was conducted. The effects of GTV size (0.5–4cm diameter), set-up margins (0, 1, and 2mm), and beam arrangements (coplanar vs non-coplanar) on the predicted TCP using IDP were assessed. For single-, three-, and five-fraction IDP dose–volume constraints of V12Gy = 10cm3, V19.2 Gy = 10cm3, and a V20Gy = 20cm3, respectively, were used to maintain a low risk of radionecrosis.
Results In BM of 4cm in diameter, the maximum achievable single-fraction IDP dose was 14Gy compared to 15Gy for standard SRS dose prescription, with respective TCPs of 32 and 42%. Fractionated SRS with IDP was needed to improve the TCP. For three- and five-fraction IDP, a maximum predicted TCP of 55 and 68% was achieved respectively (non-coplanar beams and a 1mm GTV-PTV margin).
Conclusions Using three-fraction or five-fraction IDP the predicted TCP can be increased safely to 55 and 68%, respectively, in large BM with a diameter of 4cm with a low risk of RN. Using IDP, the therapeutic ratio of SRS in large BM can be increased compared to current SRS dose prescription.
Keywords: Radiotherapy · Stereotactic · Dose prescription · Normal tissue tolerance · Large brain metastases

Publ.-Id: 28839 - Permalink


Impaired DNA damage response signaling by FUS-NLS mutations leads to neurodegeneration and FUS aggregate formation
Naumann, M.; Pal, A.; Goswami, A.; Lojewski, X.; Japtok, J.; Vehlow, A.; Naujock, M.; Günther, R.; Jin, M.; Stanslowsky, N.; Reinhardt, P.; Sterneckert, J.; Frickenhaus, M.; Pan-Montojo, F.; Storkebaum, E.; Poser, I.; Freischmidt, A.; Weishaupt, J. H.; Holzmann, K.; Troost, D.; Ludolph, A. C.; Boeckers, T. M.; Liebau, S.; Petri, S.; Cordes, N.; Hyman, A. A.; Wegner, F.; Grill, S. W.; Weis, J.; Storch, A.; Hermann, A.;
Amyotrophic lateral sclerosis (ALS) is the most frequent motor neuron disease. Cytoplasmic fused in sarcoma (FUS) aggregates are pathological hallmarks of FUS-ALS. Proper shuttling between the nucleus and cytoplasm is essential for physiological cell function. However, the initial event in the pathophysiology of FUS-ALS remains enigmatic. Using human induced pluripotent stem cell (hiPSCs)-derived motor neurons (MNs), we show that impairment of poly(ADP-ribose) polymerase (PARP)-dependent DNA damage response (DDR) signaling due to mutations in the FUS nuclear localization sequence (NLS) induces additional cytoplasmic FUS mislocalization which in turn results in neurodegeneration and FUS aggregate formation. Our work suggests that a key pathophysiologic event in ALS is upstream of aggregate formation. Targeting DDR signaling could lead to novel therapeutic routes for ameliorating ALS.

Publ.-Id: 28837 - Permalink


Differential effects of α-catenin on the invasion and radiochemosensitivity of human colorectal cancer cells
Förster, S.; Hehlgans, S.; Rödel, F.; Otto, B.; Cordes, N.;
Driven by genetic and epigenetic alterations, progression, therapy resistance and metastasis are frequent events in colorectal cancer (CRC). Although often speculated, the function of cell-cell contact for radiochemosensitivity, particularly associated with E-cadherin/catenin complex, warrants further clarification. In this study, we investigated the role of the E-cadherin/catenin complex proteins under more physiological three-dimensional (3D) cell culture conditions in a panel of CRC cell lines. In contrast to floating spheroids and growth in the laminin-rich matrix, collagen type 1 induced the formation of two distinct growth phenotypes, i.e., cell groups and single cells, in 5 out of the 8 CRC cell lines.
Further characterization of these subpopulations revealed that, intriguingly, cell-cell contact proteins are important for invasion, but negligible for radiochemosensitivity, proliferation and adhesion. Despite the generation of genomic and transcriptomic data, we were unable to elucidate the mechanisms through which α-catenin affects collagen type 1 invasion. In a retrospective analysis of patients with rectal carcinoma, a low α-catenin expression trended with overall survival, as well as locoregional and distant control. Our results suggest that the E-cadherin/catenin complex proteins forming cell-cell contacts are mainly involved in the invasion, rather than the radiochemosensitivity of 3D grown CRC cells. Further studies are warranted in order to provide a better understanding of the molecular mechanisms controlling cell-cell adhesion in the context of radiochemoresistance.
Keywords: colorectal cancer, α-catenin, radiochemotherapy, E-cadherin

Publ.-Id: 28836 - Permalink


Pretherapeutic FDG–PET total metabolic tumor volume predicts response to induction therapy in pediatric Hodgkin’s lymphoma
Rogasch, J.; Hundsdoerfer, P.; Hofheinz, F.; Wedel, F.; Schatka, I.; Amthauer, H.; Furth, C.;
Background

Standardized treatment in pediatric patients with Hodgkin’s lymphoma (HL) follows risk stratification by tumor stage, erythrocyte sedimentation rate and tumor bulk. We aimed to identify quantitative parameters from pretherapeutic FDG-PET to assist prediction of response to induction chemotherapy.

Methods

Retrospective analysis in 50 children with HL (f:18; m:32; median age, 14.8 [4–18] a) consecutively treated according to EuroNet-PHL-C1 (n = 42) or -C2 treatment protocol (n = 8). Total metabolic tumor volume (MTV) in pretherapeutic FDG-PET was defined using a semi-automated, background-adapted threshold. Metabolic (SUVmax, SUVmean, SUVpeak, total lesion glycolysis [MTV*SUVmean]) and heterogeneity parameters (asphericity [ASP], entropy, contrast, local homogeneity, energy, and cumulative SUV-volume histograms) were derived. Early response assessment (ERA) was performed after 2 cycles of induction chemotherapy according to treatment protocol and verified by reference rating. Prediction of inadequate response (IR) in ERA was based on ROC analysis separated by stage I/II (1 and 26 patients) and stage III/IV disease (7 and 16 patients) or treatment group/level (TG/TL) 1 to 3.


Results

IR was seen in 28/50 patients (TG/TL 1, 6/12 patients; TG/TL 2, 10/17; TG/TL 3, 12/21). Among all PET parameters, MTV best predicted IR; ASP was the best heterogeneity parameter. AUC of MTV was 0.84 (95%-confidence interval, 0.69–0.99) in stage I/II and 0.86 (0.7–1.0) in stage III/IV. In patients of TG/TL 1, AUC of MTV was 0.92 (0.74–1.0); in TG/TL 2 0.71 (0.44–0.99), and in TG/TL 3 0.85 (0.69–1.0). Patients with high vs. low MTV had IR in 86 vs. 0% in TG/TL 1, 80 vs. 29% in TG/TL 2, and 90 vs. 27% in TG/TL 3 (cut-off, > 80 ml, > 160 ml, > 410 ml).

Conclusions

In this explorative study, high total MTV best predicted inadequate response to induction therapy in pediatric HL of all pretherapeutic FDG-PET parameters – in both low and high stages as well as the 3 different TG/TL.
Keywords: Pediatric Hodgkin’s lymphoma Early response assessment FDG-PET Metabolic tumor volume Asphericity

Publ.-Id: 28835 - Permalink


Enhancement of the effective mass at high magnetic fields in CeRhIn5
Jiao, L.; Smidman, M.; Kohama, Y.; Wang, Z. S.; Graf, D.; Weng, Z. F.; Zhang, Y. J.; Matsuo, A.; Bauer, E. D.; Lee, H.; Kirchner, S.; Singleton, J.; Kindo, K.; Wosnitza, J.; Steglich, F.; Thompson, J. D.; Yuan, H. Q.;
The Kondo-lattice compound CeRhIn5 displays a field-induced Fermi surface reconstruction at B* ≈ 30 T, which occurs within the antiferromagnetic state, prior to the quantum critical point at Bc0 ≈ 50 T. Here, in order to investigate the nature of the Fermi surface change, we measured the magnetostriction, specific heat, and magnetic torque of CeRhIn5 across a wide range of magnetic fields. Our observations uncover the field-induced itineracy of the 4f electrons, where above Bonset ≈ 17 T there is a significant enhancement of the Sommerfeld coefficient, and spin-dependent effective cyclotron masses determined from quantum oscillations. Upon crossing Bonset , the temperature dependence of the specific heat also shows distinctly different behavior from that at low fields. Our results indicate that the Kondo coupling is remarkably robust upon increasing the magnetic field. This is ascribed to the delocalization of the 4f electrons at the Fermi surface reconstruction at B*.

Publ.-Id: 28834 - Permalink


Concise Review: Prostate Cancer Stem Cells: Current Understandin
Skvortsov, S.; Skvortsova, I. I.; Tang, D. G.; Dubrovska, A.;
Prostate cancer (PCa) is heterogeneous, harboring phenotypically diverse cancer cell types. PCa cell heterogeneity is caused by genomic instability that leads to the clonal competition and evolution of the cancer genome and by epigenetic mechanisms that result in subclonal cellular differentiation. The process of tumor cell differentiation is initiated from a population of prostate cancer stem cells (PCSCs) that possess many phenotypic and functional properties of normal stem cells. Since the initial reports on PCSCs in 2005, there has been much effort to elucidate their biological properties, including unique metabolic characteristics. In this Review, we discuss the current methods for PCSC enrichment and analysis, the hallmarks of PCSC metabolism, and the role of PCSCs in tumor progression.
Keywords: Prostate • Cancer • Cancer stem cells • Heterogeneity • Metabolism

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Publ.-Id: 28833 - Permalink


Field-induced phases in a heavy-fermion U(Ru0.92Rh0.08)2Si2 single crystal
Prokes, K.; Förster, T.; Huang, Y.-K.; Mydosh, J. A.;
We report the high-field-induced magnetic phases and phase diagram of a high quality U(Ru0.92Rh0.08 )2Si2 single crystal prepared using a modified Czochralski method. Our paper, that combines high-field magnetization and electrical resistivity measurements, shows for fields applied along the c-axis direction three field-induced magnetic phase transitions at μ0Hc1 = 21.60, μ0Hc2 = 37.90, and μ0Hc3 = 38.25 T, respectively. In agreement with a microscopic up-up-down arrangement of the U magnetic moments the phase above Hc1 has a magnetization of about one-third of the saturated value. In contrast the phase between Hc2 and Hc3 has a magnetization that is a factor of 2 lower than above the Hc3 where a polarized Fermi-liquid state with a saturated moment Ms ≈ 2.1μB/U is realized. Most of the respective transitions are reflected in the electrical resistivity as sudden drastic changes. Most notably, the phase between Hc1 and Hc2 exhibits substantially larger values. As the temperature increases, transitions smear out and disappear above ≈15 K. However, a substantial magnetoresistance is observed even at temperatures as high as 80 K. Due to a strong uniaxial magnetocrystalline anisotropy, a very small field effect is observed for fields applied perpendicular to the c-axis direction.

Publ.-Id: 28832 - Permalink


Jahn-Teller effect problems via ultrasonic experiments. Application to the impurity crystal CdSe:Cr
Averkiev, N. S.; Bersuker, I. B.; Gudkov, V. V.; Zhevstovskikh, I. V.; Sarychev, M. N.; Zherlitsyn, S.; Yasin, S.; Korostelin, Y. V.; Surikov, V. T.;
Based on the data analysis of ultrasonic experiments, a novel approach has been developed to explore Jahn-Teller effect (JTE) problems in non-cubic crystals with JT centers without involving additional experimental data beyond the information about the electronic term and crystal symmetry. Distinguished from cubic crystals, the axis of symmetry of the bulk non-cubic crystal do not necessarily coincide with those of the local impurity center, thus complicating the relation between the distortions produced by the ultrasound wave and the JTE active modes. We analysed the problem with corresponding calculations for the wurtzite-type hexagonal crystal CdSe:Cr2+, in which the chromium ion substitutes the cadmium one in the tetrahedral environment, resulting in its electronic ground state 5T2(e2t2). Experimental investigation of this system by ultrasound at frequencies of 28-105 MHz in the temperature range of 4-180 K, yields a peak in the attenuation of the ultrasound below 40 K for the normal modes related to the c 11, c 44, c 55, c 55, and c 66 elastic moduli. The peak has been interpreted as the manifestation of the JTE, similar to the one, observed in cubic crystals doped with 3d ions. However, no anomalies of attenuation have been detected for the mode related to the c 33 elastic modulus, in contradiction to the theoretical predictions based on the previous method, worked out for cubic crystals. In the new method we obtained direct relations between the deformations, related to the crystal moduli, and the local JT modes, calculated the partition functions for each of the three possible JTE problems for systems with an electronic T term, T⊗e, T⊗t2 and T⊗(e + t2) revealed how these deformations alter the vibronic energy levels responsible for the relaxations in the JT centers. It emerged that in the wurtzite crystal under consideration, only in the T⊗e problem the deformation related to the elastic moduli c 33 displaces all the vibronic energy level uniformly, without relaxation possibilities, thus supporting the new method and explaining the experimental observations.

Publ.-Id: 28831 - Permalink


Changing the properties of GaAs via strain engineering in core/shell nanowires
Balaghi, L.; Bussone, G.; Grifone, R.; Hübner, R.; Grenzer, J.; Shan, S.; Fotev, I.; Pashkin, A.; Ghorbani-Asl, M.; Krasheninnikov, A.; Schneider, H.; Helm, M.; Dimakis, E.;
III-V compound semiconductors have fueled many breakthroughs in photonics owing to their direct optical band gap and the possibility to tailor it in ternary or quaternary alloys by selecting the chemical composition appropriately. More recently, III-V semiconductors in the form of free-standing nanowires have found new strengths for a wide range of future applications in nanotechnology, including nano-photonics. Here we explore the great possibilities for strain engineering in core/shell nanowires as an alternative route to tailor the optical band gap of III-V semiconductors without changing their chemical composition. In particular, we demonstrate that the GaAs core in GaAs/InxGa1-xAs or GaAs/InxAl1-xAs core/shell nanowires can sustain unusually large misfit strains that would have been impossible in equivalent thin-film heterostructures, and undergoes a significant modification of its electronic proper-ties.

Core/shell nanowires were grown in the self-catalyzed mode on SiOx/Si(111) substrates by molecular beam epitaxy [1, 2]. Strain analysis was performed using synchrotron X-ray diffraction and Raman scat-tering spectroscopy, and showed that for a thin enough core, the magnitude and the spatial distribution of the built-in misfit strain can be regulated via the composition and the thickness of the shell. Beyond a critical shell thickness, we obtain a heavily tensile-strained core and an almost strain-free shell. The tensile strain of the core exhibits a predominantly-hydrostatic character and causes the reduction of the GaAs band gap energy (Figure 1) in accordance with our theoretical predictions using deformation-potential theory and first-principle calculations. For 7 % of strain (x = 0.54), the band gap energy was reduced to 0.87 eV at 300 K, i.e. a remarkable reduction of 40 %. This is particularly important for ap-plications in optical fiber telecommunications because the emission from strained GaAs nanowires can now cover the O-band and potentially the S-band of telecommunication wavelengths.

Besides the optical band gap, a similar reduction is expected for the effective mass of free electrons in tensile-strained GaAs. The corresponding electron mobility was estimated by time-domain terahertz spectroscopy to be in the range of 4000 – 5000 cm2/V·s at 300 K (core diameter = 22 nm, x = 0.39–0.49). These values are the highest reported, even in comparison to GaAs/AlxGa1-xAs nanowires with double the core thickness. This means that high-mobility transistors could now be possible with strained GaAs nanowires.

All in all, our results demonstrate that strained GaAs in core/shell nanowires can resemble the electronic properties of InxGa1-xAs, which makes it suitable for near-infrared nano-photonics. The use of a binary alloy instead of a ternary one would be advantageous because phenomena like phase separation, surface segregation or alloy disorder that typically exist in ternary alloys and limit the performance of photonic or electronic devices, become now irrelevant.
  • Invited lecture (Conferences)
    Nanostructures for Photonics, 07.05.2018, Saint Petersburg, Russia

Publ.-Id: 28829 - Permalink


Broadband photo-excited coherent acoustic frequency combs and mini-Brillouin-zone modes in a MQW-SESAM structure
Li, C.; Gusev, V.; Dimakis, E.; Dekorsy, T.; Hettich, M.;
A multiple quantum-well semiconductor saturable absorber mirror (MQW-SESAM) structure has been investigated by femtosecond pump-probe laser spectroscopy at a central wavelength of around 1050 nm. Coherent acoustic phonons are generated and detected over a wide frequency range from ~15 GHz to ~800 GHz. In the optical absorption region, i.e., in the multiple quantum wells (In0.27Ga0.73As), acoustic frequency combs centered at ~365 GHz, with a comb spacing of ~33 GHz, are generated. Most importantly, in the transparent region, i.e., in the distributed Bragg reflector, which is formed by a non-doped long-period semiconductor GaAs/Al0.95Ga0.05As superlattice, the mini-Brillouin-zone center, as well as zone-edge acoustic modes, are observed. The mini-zone-center modes with a fundamental frequency of 32 GHz can be attributed to the spatial modulation of the pump optical interference field with a period very close to that of the distributed Bragg reflector, in combination with the periodic spatial modulation of the electrostriction coefficient in the distributed Bragg reflector. The excitation of mini-zone-edge modes is attributed to the stimulated subharmonic decay of the fundamental center modes. Their subsequent back-folding to the mini-Brillouin-zone center makes them Raman active for the probe light.
Keywords: coherent acoustic phonons; pump-probe spectroscopy; quantum well; semiconductor superlattice; mini-Brillouin-zone; high-speed asynchronous optical sampling
  • Open Access LogoApplied Sciences 9(2019), 289

Publ.-Id: 28828 - Permalink


Structural and optical properties of pulsed-laser deposited crystalline β-Ga2O3 thin films on silicon
Berencén, Y.; Xie, Y.; Wang, M.; Prucnal, S.; Rebohle, L.; Zhou, S.;
Crystalline β-Ga2O3 thin films on (100)- and (111)-oriented Si substrates are produced by pulsed laser deposition. The as-deposited thin films are demonstrated to be polycrystalline and contain a slight deficit of oxygen atoms as measured by x-ray diffraction spectroscopy and Rutherford backscattering spectrometry, respectively. The crystallographic orientation of the Si substrate is found to play no role on the ultimate properties of the films. A direct optical band gap of 4.8 eV is determined by temperature-dependent photoluminescence excitation (PLE). Temperature-dependent PLE spectra reveal the existence of a deep acceptor level of around 1.1 eV with respect to the valence band related to self-trapped holes. We experimentally demonstrate that point defects in O-poor β-Ga2O3 thin films act as deep donors and the optical transitions are found to take place via recombination of electrons from one of the intrinsic deep donor levels with self-trapped holes located at 1.1 eV above the valence band. The 3.17 eV ultraviolet photoluminescence is proven to be related to self-trapped holes in a small polaron state between two O(II)-s sites, whereas the two blue (2.98, 2.72 eV) and the green (2.39 eV) luminescence bands are mainly originated from gallium-oxygen vacancy pairs in the (1-) charge state, gallium vacancies in the (2-) charge state and neutral oxygen interstitials, respectively.
Keywords: β-Ga2O3 thin film on Si, pulsed laser deposition, photoluminescence, substrate orientation

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Publ.-Id: 28824 - Permalink


On defects role in enhanced perpendicular magnetic anisotropy in Pt/Co/Pt, induced by ion irradiation
Jakubowski, M. M.; Liedke, M. O.ORC; Butterling, M.; Dynowska, E.; Sveklo, I.; Milińska, E.; Kurant, Z.; Böttger, R.; von Borany, J.; Maziewski, A.; Wagner, A.; Wawro, A.
Modifications of magnetic and magneto-optical properties of Pt/Co(dCo)/Pt upon Ar+ irradiation (with energy 1.2, 5 and 30 keV) and fluence, F at the range from 2e13-2e16 Ar+/cm^2) were studied. Two ‘branches’ of increased perpendicular magnetic anisotropy (PMA) and enhanced magneto-optical response are found on two-dimensional (dCo, F) diagrams. The difference in F between ‘branches’ is driven by ion energy. Structural features correlated with magnetic properties have been analysed thoroughly by X-ray diffraction, Rutherford backscattering spectrometry and positron annihilation spectroscopy. Experimental results are in agreement with TRIDYN numerical calculations of irradiation-induced layers intermixing. Our work discusses particularly structural factors related to crystal lattice defects and strain, created and modified by irradiation, co-responsible for the increase in PMA.
Keywords: thin films; magnetic measurements; vacancy formation; Rutherford backscattering, RBS; atom, molecule, and ion impact; positron spectroscopies

Publ.-Id: 28819 - Permalink


[11C]-Methionine-PET/MRI is superior to MRI alone for detecting residual tumor burden in glioblastoma multiforme undergoing radical radiochemotherapy – analysis of a prospective trial
Beuthien-Baumann, B.; Seidlitz, A.; Platzek, I.; Petr, J.; Kotzerke, J.; Jentsch, C.; Löck, S.; Zessin, J.; Krex, D.; Zöphel, K.; Schackert, G.; van den Hoff, J.; Baumann, M.; Krause, M.;
kein Abstrakt vorhanden
Keywords: [11C]Methionin, Glioblastoma, Positronen-Emissions-Tomographie
  • Abstract in refereed journal
    European Journal of Nuclear Medicine and Molecular Imaging 45(2018)S1, OP-088

Publ.-Id: 28817 - Permalink


Influence of microscopic precipitate structures on macroscopic pattern formation in reactive flows in a confined geometry
Balog, E.; Bittmann, K.; Schwarzenberger, K.; Eckert, K.; de Wit, A.; Schuszter, G.;
Thanks to the coupling between chemical precipitation reactions and hydrodynamics, new dynamic phenomena may be obtained and new types of materials can be synthesized. Here we experimentally investigate how the characteristic microscopic crystal properties affect the macroscopic pattern obtained. To shed light on such interactions, different reactant solutions are radially injected into a calcium chloride solution at different volumetric flow rates in a confined geometry. Depending on the reactants used and the flow conditions, deformed precipitate membranes have been observed due to reaction-driven viscous fingering. In such cases we show that upon injection a large number of small particles is produced in situ by the reaction at the miscible interface between the two reactant solutions. Therefore, a colloidal gel composed of those tiny particles is pushed forward by the injected aqueous solution giving rise to a viscosity gradient-driven hydrodynamic instability.

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Publ.-Id: 28812 - Permalink


Predictive Geometallurgy
Gutzmer, J.; Birtel, S.; Büttner, P.; Bachmann, K.; Kern, M.; Frenzel, M.;
For centuries the German proverb “Vor der Hacke ist es duster” has aptly described the lack of knowledge about ore volumes, grades and beneficiation characteristics during the incremental progress of mining operations. Although much progress has been made constraining ore volumes and grades by following rigorous exploration drilling programs and applying appropriate geostatistical and spatial modelling tools, there still remains considerable technical risk when exploration turns into exploitation. This is illustrated by the observation that ca. 70% of mines perform below the prediction of their feasibility study (Wood, 2018). This underperformance is usually attributed to deficiencies in the collection of tangible geoscientific data needed to design the mine and the minerals processing plant (Wood, 2018).
Geometallurgy is an interdisciplinary approach that aims to connect the data available from geosciences with the information required to predict the performance of technologies used for ore extraction and mineral beneficiation. Tangible resource characteristics – beyond grade and tonnage - are quantified to create a model that links the geology of an ore deposit with the performance achieved during mining, mineral processing and extractive metallurgy. Successful geometallurgical programs may thus be used to mitigate the risk of production planning and plant design. However, the tools of geometallurgy have thus far mostly been used by the mining industry to improve metal recoveries and to monitor process efficiency of mineral processing plants only.
Present research goes beyond these current applications of geometallurgy. Predictive geometallurgical models for complex ore bodies and even anthropogenic raw materials are being developed by interdisciplinary teams including expertise in exploration, resource characterization, minerals processing, geostatistics and spatial modelling. Case studies will be presented in this contribution that illustrate the approach taken. These examples include (1) the recovery of Sn from a historic flotation tailings storage facility; (2) the recovery of PGE as a by-product of chromite exploitation; and (3) the intelligent use of quantitative mineral abundance and mineral association data to predict the prospects of success of sensor-based sorting.
Results obtained in the three case studies illustrate the prospects of increasing resource and energy efficiency in the mining industry. Innovative approaches are of general applicability and can be easily extended to other metals and ore deposit types. The results clearly illustrate the value of conducting comprehensive geometallurgical assessments already during the latter stages of exploration; the initial process of constructing a predictive geometallurgical model will, of course, benefit greatly from regular follow-up during the phase of active exploitation.
Keywords: geometallurgy, geosciences, minerals processing, metallurgy
  • Invited lecture (Conferences)
    4th GOOD Meeting, 23.-25.01.2019, Bremen, Germany
  • Contribution to proceedings
    4th GOOD Meeting, 23.-25.01.2019, Bremen, Germany
    4th GOOD Meeting Abstract Volume, Bremen

Publ.-Id: 28808 - Permalink


Corrigendum to “Synchrotron tomographic quantification of the influence of Zn concentration on dendritic growth in Mg-Zn alloys” [Acta Mater. 156 (2018) 287-296]
Phillion, A.; Shuai, S.; Guo, E.; Wang, J.; Jing, T.; Ren, Z.; Neumann-Heyme, H.; Beckermann, C.; Lee, P.;
In solidification science, the solid-liquid interfacial area density is a key metric that characterizes the overall semi-solid morphology in a general sense. This interfacial area density can be defined in two different ways... [Abstract not available for Corrigenda]

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Publ.-Id: 28807 - Permalink


Geometric reconstruction of 3D dendrite evolution from 2D transmission radiography data by a simple phase-field method
Neumann-Heyme, H.;
For the in-situ observation of dynamical processes radiographic imaging possess significant advantages over tomographic reconstruction in terms of e.g. time resolution and data handling. However, on the other hand essential spatial information is lost in the projected 2D image. The proposed method demonstrates, how in the case of continuously growing, coherent structures such as dendrites their time evolution can be utilized in recovering the 3D morphology. In addition, the reconstruction incorporates some prior knowledge including the smoothness and preferential growth directions of the interface. The capabilities of the method are assessed for different situations based on simulated experiments of dendritic growth. Finally, the reconstruction of evolving dendrites from flat sample synchrotron experiments is shown.
  • Lecture (Conference)
    55th Annual Technical Meeting of the Society of Engineering Science (SES2018), 10.-12.10.2018, Madrid, Spain

Publ.-Id: 28806 - Permalink


4D particle tracking velocimetry to analyze bubble-particles collisions and flotation recovery at low Stokes numbers
Sommer, A.-E.ORC; Heitkam, S.; Eckert, K.ORC
Froth flotation is a fundamental technique to separate minerals. Hydrophobized target particles attach to the fluidic interface of gas bubbles rising in a suspension. The success of the process depends on both the surface chemistry for the hydrophobization of particles and the hydrodynamics for an encounter between bubble and particle. In the first part of the talk on overview about flotation research and modeling is given.
The second part of the talk is devoted to own research on the hydrodynamics in model cells. To quantify this performance in terms of recovery, the number of target particles at various times in a reference volume is measured. One of the remaining challenges in this field is the flotation of fine particles with a size below 10 µm. Caused by their small inertia, the particles follow the streamlines around the bubble and no collision occurs [1]. This work focuses on the measurement of the collision probability of particles with a small inertia at the bubble surface to advance our understanding of relevant microprocesses and its influence on the flotation recovery. With a 4D particle tracking velocimetry device the particle and bubble trajectories were measured simultaneously with a high temporal (1000 fps) and spatial resolution (0.03 mm/pixels). We developed an algorithm to evaluate the flotation recovery based on the collision and attachment probability [2]. The three-phase flow within a rectangular bubble column consisted of fluorescent polystyrene particles (33 µm, 1.05 g/cm3), a bubble chain (1-7 mm) and deionized water with methanol. The variation of the bubble diameter and methanol concentration led to a change of the fluid flow around the bubble (Re = 100 - 1200) and the particle hydrophobization. The results show the preferred collision of the particles at the rear of the bubble due to a higher acceleration within the vortices in the wake.

[1] Yoon and Luttrell, Mineral Processing and Extractive Metallurgy Review 5, 101 (1989).
[2] AE Sommer, M Nikpay, S Heitkam, M Rudolph, K Eckert, Minerals Engineering 124, 116-122 (2018)
Keywords: flotation, particle image velocimetry
  • Invited lecture (Conferences)
    Permsker Wissenschaftliche Lesung, 24.-28.9.2018, Perm, Rusland

Publ.-Id: 28805 - Permalink


Coarsening and refinement phenomena in dendritic solidification
Neumann-Heyme, H.; Eckert, K.; Beckermann, C.;
Curvature-driven interface motion plays an important role in the formation of the final microstructure during dendritic solidification. Usually, such motion results in a coarser microstructure via coalescence or retraction of dendrite sidebranches \cite{ref1}. Under certain conditions, however, the microstructure can be refined due to curvature-driven pinching events that lead to dendrite fragmentation. Such pinching events are a strong function of the size and shape of the initial dendrite structure \cite{ref2}. In the present study, two- and three-dimensional phase-field simulations are performed to investigate coarsening and refinement phenomena during directional solidification of alloys. The phase-field model is solved using a finite element library that permits adaptive mesh refinement and exhibits wide parallel scalability on supercomputing facilities. A semi-implicit time integration scheme is used to allow for adaptive time stepping, which is important in particular, since curvature-driven interface motion occurs on significantly larger time scales than the initial growth. The present talk will focus on some characteristics of the applied model and physical insights that were obtained.
  • Lecture (Conference)
    5th GAMM Workshop on Phase-Field Modeling, 08.-09.02.2018, TU Dresden, Germany

Publ.-Id: 28804 - Permalink


Evaluation of Brain Nuclear Medicine Imaging Tracers in a Murine Model of Sepsis-Associated Encephalopathy
Szöllősi, D.; Hegedűs, N.; Veres, D. S.; Futó, I.; Horváth, I.; Kovács, N.; Martinecz, B.; Dénes, Á.; Seifert, D.; Bergmann, R.; Lebeda, O.; Varga, Z.; Kaleta, Z.; Szigeti, K.; Máthé, D.;
Purpose: The purpose of this study was to evaluate a set of widely used nuclear medicine imaging agents as possible methods to study the early effects of systemic inflammation on the living brain in a mouse model of sepsis-associated encephalopathy (SAE). The lipopolysaccharide (LPS)-induced murine systemic inflammation model was selected as a model of SAE.
Procedures: C57BL/6 mice were used. A multimodal imaging protocol was carried out on each animal 4 h following the intravenous administration of LPS using the following tracers: [99mTc][2,2-dimethyl-3-[(3E)-3-oxidoiminobutan-2-yl]azanidylpropyl]-[(3E)-3-hydroxyiminobutan-2-yl]azanide ([99m
Tc]HMPAO) and ethyl-7-[125I]iodo-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]ben-zodiazepine-3-carboxylate ([125I]iomazenil) to measure brain perfusion and neuronal damage, respectively; 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) to measure cerebral glucose uptake.
We assessed microglia activity on another group of mice using 2-[6-chloro-2-(4-[125I]iodo-phenyl)-imidazo[1,2-a]pyridin-3-yl]-N-ethyl-N-methyl-acetamide ([125I]CLINME). Radiotracer uptakes were measured in different brain regions and correlated. Microglia activity was also assessed using immunohistochemistry. Brain glutathione levels were measured to investigate oxidative stress.
Results: Significantly reduced perfusion values and significantly enhanced [18F]FDG and [125I]CLINME uptake was measured in the LPS-treated group. Following perfusion compensation, enhanced [125I]iomazenil uptake was measured in the LPS-treated group’s hippocampus and cerebellum. In this group, both [18F]FDG and [125I]iomazenil uptake showed highly negative correlation to perfusion measured with ([99mTc]HMPAO uptake in all brain regions. No significant differences were detected in brain glutathione levels between the groups. The CD45 and P2Y12 double-labeling immunohistochemistry showed widespread microglia activation in the LPS-treated group.
Conclusions: Our results suggest that [125I]CLINME and [99mTc]HMPAO SPECT can be used to detect microglia activation and brain hypoperfusion, respectively, in the early phase (4 h post injection) of systemic inflammation. We suspect that the enhancement of [18F]FDG and [125I]iomazenil uptake in the LPS-treated group does not necessarily reflect neural hypermetabolism and the lack of neuronal damage. They are most likely caused by processes emerging during neuroinflammation, e.g., microglia activation and/or immune cell infiltration.
Keywords: Systemic infection, Neuroinflammation, Microglia activation, LPS, [99mTc]HMPAO, [18F]FDG, [125I]iomazenil, [125I]CLINME, SPECT/CT, PET/MRI

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  • Secondary publication expected from 07.05.2019

Publ.-Id: 28803 - Permalink


Effects of electron beam generated lattice defects on the periodic lattice distortion structure in 1T-TaS2 and 1T-TaSe2 thin layers
Kinyanjui, M. K.; Björkman, T.; Lehnert, T.; Köster, J.; Krasheninnikov, A.ORC; Kaiser, U.
We have investigated the influence of electron beam generated defects on the structure of periodic lattice distortions (PLDs) which accompany charge density wave modulations in 1T -TaS2 and 1T -TaSe2 . Lattice defects were generated through irradiation with high-energy electrons in a transmission electron microscope (TEM). Using atomically resolved high-resolution TEM imaging, we investigate the PLD structure and the changes in this structure with prolonged exposure to the electron beam. We observe the formation of dislocationlike topological defects in the PLD structure. Prolonged exposure to the electron beam also leads to an increase in density of these defects. This is also accompanied by an increase in structural disorder of the PLD. Density functional theory calculations were also performed in order to understand sulfur (S) and selenium (Se) vacancy defect formation in 1T -TaSe2 and 1T -TaS2 and their effects on the PLD structure. The formation energy of Se/S vacancies was calculated to be lowest for the highly displaced S/Se atoms in the vicinity of PLD maxima. Vacancies formed at the less displaced sites near the PLD minima were found to have lower formation energy. The calculations also showed that an increase in the S/Se vacancies leads to the formation of dislocations and an increase in disorder in the PLD structures. This supports the experimental observations.
Keywords: TEM, 2D materials, first-principles calculations

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Publ.-Id: 28802 - Permalink


Characterization of continuous wave laser-induced thermal gradients in magnetic tunnel junctions integrated into microresonators via COMSOL simulations
Cansever, H.ORC; Lindner, J.; Huebner, T.; Niesen, A.; Reiss, G.; Fassbender, J.; Deac, A. M.
Spin caloritronics still is a vivid field and aims to investigate static and dynamic effects on magnetic structures due to spin-currents generated by thermal gradients [1]. In magnetic tunnel junctions, magnetization dynamics can be induced by bias voltage as well as thermal gradients [2]. In most research, COMSOL simulations are used to estimate the overall temperature of the magnetic tunnel junction as well as the thermal gradient over the insulating barrier [3-5]. Here, we perform COMSOL simulations using the 2D heat transfer module for specific Co2FeAl/MgO(2nm)/CoFeB magnetic tunnel junctions which are integrated into so-called microresonators [6]. Microresonators have been recently used as alternative approach to investigate the magnetization dynamics of the free-layer within magnetic tunnel junctions, induced by a thermal gradient by means of its ferromagnetic resonance response [6]. Utilizing microresonators for ferromagnetic resonance detection allow for the detection of signals from micron/nano-sized object under laser heating in terms of linewidth and resonance field and thus provide the possibility to detect influences of a thermal gradient on the magnetization dynamics far below the threshold of magnetic switching. The heat diffusion over all layers are modeled by starting with a 2D (vertical) rectangular shape in which we consider the MTJ stack with the MgO-substrate and backside metallization as part of the microresonators shown in Fig 1. Moreover, we consider an air ‘layer’ and the metal-contacts defining the microresonator on top of the MgO-substrate. Upon rotation of this two-dimensional shape around the central vertical z-axis of the MTJ, we obtain a 3D cylinder in which the heat profile is simulated (see Fig 2). The simulation parameters for the materials were chosen similar to those in [3,4]. In the simulation, the fundamental properties of layers i.e. thermal conductivity, heat capacity and material density are used to obtain a temperature profile of the magnetic structure. According to the simulation results, the thermal conductivity of the insulating barrier (MgO) and top metal thicknesses influence the thermal gradient, while uniform heating is strongly affected by the surrounding material of the microresonator which is mainly made from copper (high thermal conductivity). The simulation results provide insight into the heat profile of the whole structure and in particular demonstrate that not only changing the magnetic object itself but also modifying the structure of the surrounding materials yields a handle to tune and optimize the thermal gradient.
Figure 1. 2D sketch of MTJ structure integrated into a microresonator for COMSOL modelling. Heat source, i.e. cw- laser is applied to magnetic layers through the top-metal. The temperature of the bottom of the whole structure is set to 293.15 K.
Figure 2. (a) Temperature profile across the MTJ integrated in a microresonator with the applied power of 145 mW inset (b) 3D cylindrical image of MTJ structure.


[1] Bauer G E W, Saitoh E and van Wees B J 2012 Nat. Mater. 11 391
[2] Jia X, Xia K and Bauer G E W 2011 Phys. Rev. Lett.107 176603
[3] Walter M et al 2011 Nat. Mater. 10 742
[4] Huebner T, Boehnke A, Martens U, Thomas A, Schmalhorst J M, Reiss G, Münzenberg M and Kuschel T 2016 Phys. Rev. B 93 224433
[5] T Huebner et al 2018 J. Phys. D: Appl. Phys. 51 224006
[6] H Cansever et al 2018 J. Phys. D: Appl. Phys. 51 224009
Keywords: COMSOL Simulation, magnetic tunnel junction, microresonator, ferromagnetic resonance
  • Lecture (Conference)
    Joint MMM-Intermag Conference 2019 Washington D.C., 14.-18.01.2019, Washington D.C., The United States of America

Publ.-Id: 28800 - Permalink


The new Felsenkeller 5 MV underground accelerator: Status and Program
Bemmerer, D.;
Experimental nuclear astrophysics aims to study, in the laboratory, the nuclear reactions taking place in stars. However, at the energies relevant to stellar burnings, the relevant cross sections are strongly reduced by the repulsive Coulomb barrier. As a result, ion beam experiments in underground laboratories shielded from cosmic ray effects are needed in order to gain precise data. The Felsenkeller 5 MV accelerator, below 45 m rock in Dresden, is the first such accelerator on the MV scale in Europe. The laboratory was jointly built by HZDR and TU Dresden and opened in 2018. Both an internal and an external ion source have already been tested successfully underground. The accelerator itself is under commissioning, as well as a high-sensitivity radioactivity counting setup by TU Dresden. The talk will summarise the science case and the status for the new laboratory.
Keywords: Nuclear Astrophysics
  • Invited lecture (Conferences)
    Institutsseminar (Kolloquium), 24.01.2019, Dresden, Deutschland

Publ.-Id: 28797 - Permalink


Felsenkeller 5 MV underground ion accelerator status December 2018
Bemmerer, D.;
I review the status of the Felsenkeller 5 MV underground accelerator in view of the CELLAR network of underground labs.
Keywords: Nuclear Astrophysics Low-Level Radioactivity Measurements
  • Lecture (Conference)
    CELLAR / JEILORA Meeting, 05.-07.12.2018, Monaco, Monaco

Publ.-Id: 28796 - Permalink


Nuclear Astrophysics: Nucleosynthesis and Chemical Evolution Studies
Bemmerer, D.;
I review Nuclear Astrophysics: Nucleosynthesis and Chemical Evolution Studies.
Keywords: Nuclear Astrophysics
  • Invited lecture (Conferences)
    Astroparticle Physics in Germany: Status and Perspectives, 19.09.2018, Mainz, Deutschland

Publ.-Id: 28795 - Permalink


Felsenkeller 5 MV underground accelerator at the 5th International Solar Neutrino Conference
Bemmerer, D.;
I review the status of the 5 MV underground accelerator at Felsenkeller, Dresden/Germany.
Keywords: Underground physics Nuclear Astrophysics
  • Invited lecture (Conferences)
    5th International Solar Neutrino Conference, 13.06.2018, Dresden, Deutschland

Publ.-Id: 28794 - Permalink


Felsenkeller 5 MV underground ion accelerator for nuclear astrophysics
Bemmerer, D.; Cowan, T. E.; Grieger, M.; Hensel, T.; Junghans, A. R.; Koppitz, M.; Ludwig, F.; Rimarzig, B.; Reinicke, S.; Schwengner, R.; Stöckel, K.; Szücs, T.; Takács, M. P.; Turkat, S.; Wagner, A.; Zuber, K.;
A 5 MV Pelletron accelerator with both an internal and an external ion source providing for intensive 1H+, 4He+, and 12C+ beams is being installed in the Felsenkeller underground site in Dresden, shielded from cosmic rays by 45 m rock overburden. Civil construction has recently been completed. The technical features of the new laboratory, test results, and the scientific program will be summarized. In addition to in-house research by HZDR and TU Dresden, the new accelerator will be open for outside users, both from Germany and worldwide.
Keywords: Nuclear astrophysics Felsenkeller
  • Lecture (Conference)
    Frühjahrstagung Hadronen und Kerne, 26.02.2018, Bochum, Deutschland

Publ.-Id: 28793 - Permalink


Improved astrophysical rate for the 18O(p,α)15N reaction by underground measurements
Bruno, C. G.; Aliotta, M.; Descouvemont, P.; Best, A.; Davinson, T.; Bemmerer, D.; Boeltzig, A.; Broggini, C.; Caciolli, A.; Cavanna, F.; Chillery, T.; Ciani, G. F.; Corvisiero, P.; Depalo, R.; Di Leva, A.; Elekes, Z.; Ferraro, F.; Formicola, A.; Fülöp, Z.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, G.; Imbriani, G.; Junker, M.; Lugaro, M.; Marigo, P.; Menegazzo, R.; Mossa, V.; Pantaleo, F. R.; Piatti, D.; Prati, P.; Stöckel, K.; Straniero, O.; Strieder, F.; Szücs, T.; Takács, M. P.; Trezzi, D.;
The 18O(p,α)15N reaction affects the synthesis of 15N, 18O and 19F isotopes, whose abundances can be used to probe the nucleosynthesis and mixing processes occurring deep inside asymptotic giant branch (AGB) stars. We performed a low-background direct measurement of the 18O(p,α)15N reaction cross-section at the Laboratory for Underground Nuclear Astrophysics (LUNA) from center of mass energy E_CM= 340 keV down to E_CM = 55 keV, the lowest energy measured to date corresponding to a cross-section of less than 1 picobarn/sr. The strength of a key resonance at center of mass energy E_r = 90 keV was found to be a factor of 10 higher than previously reported. A multi-channel R-matrix analysis of our and other data available in the literature was performed. Over a wide temperature range, T=0.01-1.00 GK, our new astrophysical rate is both more accurate and precise than recent evaluations. Stronger constraints can now be placed on the physical processes controlling nucleosynthesis in AGB stars with interesting consequences on the abundance of 18O in these stars and in stardust grains, specifically on the production sites of oxygen-rich Group II grains.
Keywords: Stellar hydrogen burningHydrostatic stellar nucleosynthesis

Publ.-Id: 28791 - Permalink


Hyperspectral Feature Extraction Using Sparse and Smooth Low-Rank Analysis
Rasti, B.; Ghamisi, P.; Ulfarsson, M. O.;
In this paper, we develop a hyperspectral feature extraction method called sparse and smooth low-rank analysis (SSLRA). First, we propose a new low-rank model for hyperspectral images (HSIs) where we decompose the HSI into smooth and sparse components. Then, these components are simultaneously estimated using a nonconvex constrained penalized cost function (CPCF). The proposed CPCF exploits total variation penalty, ℓ1 penalty, and an orthogonality constraint. The total variation penalty is used to promote piecewise smoothness, and, therefore, it extracts spatial (local neighborhood) information. The ℓ1 penalty encourages sparse and spatial structures. Additionally, we show that this new type of decomposition improves the classification of the HSIs. In the experiments, SSLRA was applied on the Houston (urban) and the Trento (rural) datasets. The extracted features were used as an input into a classifier (either support vector machines (SVM) or random forest (RF)) to produce the final classification map. The results confirm improvement in classification accuracy compared to the state-of-the-art feature extraction approaches.

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Publ.-Id: 28790 - Permalink


The IR-truncated PT-symmetric V = ix3 model and its asymptotic spectral scaling graph
Günther, U.ORC; Stefani, F.
The PT-symmetric V = ix3 model over the real line is infra-red (IR) truncated and considered as Sturm-Liouville problem over a finite interval. Structures hidden in the Airy function setup of the V = ix3 model are combined with WKB techniques developed by Bender and Jones in 2012 for the derivation of the real part of the spectrum of theV = ix3 model. Via WKB and Stokes graph analysis, the location of the complex spectral branches of the ix3 model as well as those of more general V = -(ix)2n+1 models over finite intervals are obtained. Splitting the related action functions into purely real scale factors and scale invariant integrals allows to extract underlying asymptotic spectral scaling graphs. These (structurally very simple) scaling graphs are geometrically invariant and cutoff-independent so that the IR limit can be formally taken. Moreover an increasing length scale can be associated with a spectral UV-IR renormalization group flow on this scaling graph. It is shown that the eigenvalues of the IR-complete V = ix3 model can be bijectively mapped onto a finite segment of the scaling graph asymptotically approaching a (scale invariant) PT phase transition region. In this way, a simple heuristic picture and complementary explanation for the unboundedness of projector norms and C-operator for the ix3 model are provided and the lack of quasi-Hermiticity of the ix3 Hamiltonian over the real line appears physically plausible. Possible directions of further research are briefly sketched.
Keywords: PT Quantum Mechanics, PT phase transition, spectral branch points, exceptional points, ix3 model, WKB techniques, IR truncation, IR completion, asymptotic spectral scaling graphs, spectral UV-IR renormalization group flow
  • Invited lecture (Conferences)
    Discrete-18, organized by CERN and the Austrian Academy of Sciences, 26.-30.11.2018, Wien, Österreich

Publ.-Id: 28787 - Permalink


The IR-truncated PT-symmetric V = ix3 model and its asymptotic spectral scaling graph
Günther, U.ORC; Stefani, F.
The PT-symmetric quantum mechanical V = ix3 model over the real line is infra-red (IR) truncated and considered as Sturm-Liouville problem over a finite interval of the real line. Via WKB and Stokes graph analysis, the location of the complex spectral branches of the V = ix3 model as well as those of more general V = -(ix)2n+1 models over finite intervals are obtained. Underlying asymptotic spectral scaling graphs are extracted which are scale-invariant so that the IR completion can be performed. Implications for the V = ix3 model over the full real line are discussed.
Keywords: PT Quantum Mechanics, PT phase transition, spectral branch points, exceptional points, ix3 model, WKB techniques, IR truncation, asymptotic spectral scaling graphs
  • Invited lecture (Conferences)
    Analytic and algebraic methods in physics XV, 10.-13.09.2018, Prague, Czech Republic

Publ.-Id: 28786 - Permalink


The IR-truncated PT-symmetric V=ix3 model and its asymptotic spectral scaling graph
Günther, U.ORC; Stefani, F.
The PT-symmetric V=ix3 model over the real line is IR truncated and considered as Sturm-Liouville problem over a finite interval. Combining structures hidden in the Airy function setup of the V=ix model with WKB techniques developed by Bender and Jones in 2012 for the derivation of the real part of the spectrum of the ix3 model, a WKB and Stokes graph analysis for the complex spectral branches of the ix3 model as well as those of more general V=-(ix)2n+1 models over finite intervals is performed. Complementary insights into the spectra of these models are obtained by splitting the spectral branch-structure into purely real scale factors and asymptotic spectral scaling graphs. It turns out that the corresponding (structurally very simple) scaling graphs are geometrically invariant and cutoff-independent so that the infra-red (IR) limit can be formally taken. These graphs have invariantly existing PT phase transition regions. In this way, a simple heuristic picture and complementary explanation for the unboundedness of the C-operator and the lack of quasi-Hermiticity of the ix3 Hamiltonian over the real line is provided.
Keywords: PT-symmetric Quantum Mechanics, PT phase transition, spectral branch points, exceptional points, ix3 model, WKB techniques, IR truncation, C-operator, unboundedness, quasi-Hermiticity
  • Invited lecture (Conferences)
    Pseudo-Hermitian Hamiltonians in Quantum Physics (PHHQP) XVIII, 04.-13.06.2018, Bangalore, India

Publ.-Id: 28785 - Permalink


Curing processes in ultra low-k materials by positron annihilation spectroscopy
Liedke, M. O.ORC; Köhler, N.; Butterling, M.; Hirschmann, E.; Attallah, A. G.; Krause-Rehberg, R.; Schulz, S. E.; Wagner, A.
The first results on in-situ investigations of pore formation in ultra low-k dielectrics during a curing process, i.e., a porogen removal by vacuum annealing will be presented. The main focus is to obtain insight into initial stages of pore networks formation up to their full development. The in-situ annealing and Doppler broadening positron annihilation spectroscopy measurements have been conducted on our Apparatus for In-situ Defect Analysis (AIDA) - the end-station of a slow positrons beamline at HZDR. In addition, positron lifetime spectroscopy has been utilized, where mono-energetic pulsed positron beam (MePS) serves as a probe to evaluate pore sizes, their concentration and distribution as a function of curing temperature and time. The MePS facility has partly been funded by the Federal Ministry of Education and Research (BMBF) with the grant PosiAnalyse (05K2013). The AIDA system was funded by the Impulse- und Networking fund of the Helmholtz-Association (FKZ VH-VI-442 Memriox) and through the Helmholtz Energy Materials Characterization Platform (03ET7015)
Keywords: positron, low-k, curing, AIDA, defects, pores
  • Lecture (Conference)
    DPG Frühjahrstagung Berlin, 11.03.2018, Berlin, Deutschland

Publ.-Id: 28784 - Permalink


Vacancy-mediated magnetic phase-transitions
Liedke, M. O.ORC; Butterling, M.; Quintana, A.; Menéndez, E.; Ehrler, J.; Bali, R.; Hirschmann, E.; Sireus, V.; Nogués, J.; Sort, J.; Wagner, A.
Two thin film systems exhibiting vacancy mediated magnetic phase transitions will be discussed in detail, i.e., Co3O4 and Fe60Al40.
In applications, substituting electric currents, which are nowadays used to operate spintronic devices, with electric fields, would result in a reduction of both the energy consumption and cost [1]. Co3O4 is a candidate for a tunable, non-volatile energy-efficient functional material whose magnetic properties can be controlled by electric voltage. In our current investigations the as-grown Co3O4 films consist of a paramagnetic (PM) phase only, which is transformed to a ferromagnetic (FM) state by electrolyte-gated and defect-mediated O and Co transport. A negative voltage reduces Co3O4 to Co (FM: ON), resulting in a phase separated material with Co- and O-rich regions. Applying a positive bias, the process is reversed oxidizing Co back to Co3O4 (PM: OFF). We will show that atoms migration is driven by rather complex vacancy states and a clear increase of the grain boundaries volume after negative biasing assists to O transport. Moreover, concomitantly with the PM phase transition due to the positive biasing the structural defects picture reverses to a large extent as well, which manifests as reduction in volume of both vacancy clusters and grain boundaries.
B2-Fe60Al40 phase is paramagnetic, and strong ferromagnetism can be induced via disordering to the A2-Fe60Al40 phase [2]. Disordering implies the formation of anti-site defects [3], which correlates with an increased Fe coordination. The concentration and size of open volume defects can play an important role in reordering kinetics. Three different initial order states have been investigated: (i) as-grown, partially disordered Fe60Al40, (ii) the as-grown films after Ne+ irradiation, and (iii) Ne-irradiated B2-Fe60Al40. Since, reordering directly affects magnetization saturation; the extent of the diffusion process can be traced via magnetometry at slightly elevated temperature of 400 K. We show that immobile large vacancy clusters with a high thermal activation barrier are dominant in the as-grown film and hinder ordering. Ion irradiation breaks down these pinning sites, thereby strongly accelerating thermal diffusion and reordering. These results provide insights into thermal reordering processes in binary alloys, and the consequent effect on magnetic properties. Doppler broadening and positron annihilation lifetime spectroscopy have been used as a probe for both electric field driven ionic transport of Co and O via different type of defects in Co3O4 systems as well as vacancy-mediated ordering in Fe60Al40.
[1] Y. Shiota, et al. Nature Mater. 11, 39 (2012). [2] M.O. Liedke, et al., J. Appl. Phys. 117, 163908 (2015).
[3] R. Bali, et al., Nano Lett. 14, 435 (2014).
Keywords: magnetism, positron, ion, irradiation, phase transitions, defects, electrical fields
  • Invited lecture (Conferences)
    18th International Conference on Positron Annihilation (ICPA-18), 19.08.2018, Orlando, USA

Publ.-Id: 28783 - Permalink


Magnetic ordering and open volume defects – phase transitions in ion irradiated Fe60Al40 thin films
Liedke, M. O.ORC; Ehrler, J.; Bali, R.; Butterling, M.; Hirschmann, E.; Wagner, A.
Fe60Al40 exhibit the so-called disorder induced ferromagnetism, where anti-site disorder (ASD) promotes ferromagnetic A2-phase (disordered) over paramagnetic B2-phase (ordered). Both phases can be - in a controllable fashion - driven by ion irradiation or annealing, respectively. The main physical origin correlates strongly with ASD [R. Bali, et al., Nano Lett. 14, 435 (2014)]. Nevertheless, the concentration and size of open volume defects can be of crucial importance in determining the kinetics of the reordering processes. To unravel the influence of vacancy clusters, three different initial order states have been investigated: (i) as-sputtered, (ii) as-grown irradiated with Ne+ and (iii) B2 ordered films, obtained via 773 K annealing and Ne-irradiated. Open volume defects in the treated samples were investigated with Doppler broadening and positron annihilation lifetime spectroscopy. Furthermore, since the reordering directly affects Ms, the extent of the diffusion process can be traced via magnetometry at slightly elevated temperature of 400 K. We show that immobile large vacancy clusters are dominant in the as-grown films; these complexes present only in the as-sputtered film possess a high thermal activation barrier and hinder ordering. Ion irradiation breaks down these pinning defects strongly accelerating thermal diffusion and reordering. These results provide insights into thermal reordering processes in binary alloys, and the consequent effect on magnetic behavior.
Keywords: magnetism, positron, ordering, ion, irradiation, phase transition, defects
  • Lecture (Conference)
    9th Joint European Magnetic Symposia (JEMS-9), 03.09.2018, Mainz, Deutschland

Publ.-Id: 28782 - Permalink


On the use of stacks of fission-like targets for neutron capture experiments
Guerrero, C.; Lerendegui-Marco, J.; Eberhardt, K.; Düllmann, C. E.; Junghans, A.; Lommel, B.; Mokry, C.; Quesada, J. M.; Runke, J.; Thörle-Pospiech, P.; The N_Tof Collaboration;
The measurement of neutron induced reactions on unstable isotopes is of interest in many fields, from nuclear energy to astrophysics or applications; in particular transuranic isotopes are essential for the development of innovative nuclear reactors and for the management of the radioactive waste. In such measurements, the quality of the associated radioactive target is crucial for the success of the experiment, but in many cases the geometry, amount of mass and encapsulation of the target are not optimal, leading to limited results. In this work we propose to produce high quality radioactive targets for capture as a stack of thin targets using the techniques usually employed for fission measurements. In particular, we have succeeded in making a 242Pu target of nearly 100 mg by combining seven thin (~1 mg/cm2) fission-like targets with 45 mm in diameter achieving a total backing thickness of only 70 m of aluminum. The target has been shown to perform successfully in experiments at both a neutron time-of-flight facility (n_TOF at CERN) and a thermal neutron beam (BRR at KFKI), providing the most accurate data from thermal up to 250 keV to date.

Publ.-Id: 28781 - Permalink


Strahlenschutzaspekte bei der Errichtung und Inbetriebnahme des kanadischen Zyklotrons TR-FLEX im Helmholtz-Zentrum Dresden-Rossendorf
Preusche, S.; Naumann, B.; Kaspari, W.;
  • Invited lecture (Conferences)
    Strahlenschutz in Medizin, Forschung und Industrie, 11.-12.12.2018, Aschaffenburg, Deutschland

Publ.-Id: 28779 - Permalink


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