Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41709 Publications

Tailoring Optical Properties of Atomically-Thin WS2 via Ion Irradiation

Tan, L. N.; Tan, Y.; Ghorbani-Asl, M.; Boettger, R.; Kretschmer, S.; Zhou, S. Q.; Huang, Z. Y.; Krasheninnikov, A. V.; Chen, F.

Abstract

Two-dimensional transition metal dichalcogenides (TMDCs) exhibit excellent optoelectronic properties. However, the large band gaps in many semiconducting TMDCs make optical absorption in the near-infrared (NIR) wavelength regime impossible, which prevents applications of these materials in optical communications. In this work, we demonstrate that Ar+ ion irradiation is a powerful post-synthesis technique to tailor the optical properties of the semiconducting tungsten disulfide (WS2) by creating S vacancies and thus controlling material stoichiometry. First-principles calculations reveal that the S-vacancies give rise to deep states in the band gap, which determine the NIR optical absorption of the WS2 monolayer. As the density of the S-vacancies increases, the enhanced NIR linear and saturable absorption of WS2 is observed, which is explained by the results of first-principles calculations. We further demonstrate that by using the irradiated WS2 as a saturable absorber in a waveguide system, the passively Q-switched laser operations can be optimized, opening thus new avenues for tailoring the optical response of TMDCs by defect-engineering through ion irradiation.

Keywords: Ion irradiation; WS2; optical properties

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Permalink: https://www.hzdr.de/publications/Publ-25650


Laser-Ablation-Based Ion Source Characterization and Manipulation for Laser-Driven Ion Acceleration

Sommer, P.; Metzkes, J.; Brack, F.-E.; Cowan, T. E.; Kraft, S. D.; Obst, L.; Rehwald, M.; Schlenvoigt, H.-P.; Schramm, U.; Zeil, K.

Abstract

For laser-driven ion acceleration from thin foils (~10 µm- 100 nm) in the target normal sheath acceleration (TNSA) regime, the hydro-carbon contaminant layer at the target surface generally serves as the ion source and hence determines the accelerated ion species, i.e. mainly protons, carbon and oxygen ions. The specific characteristics of the source layer - thickness and relevant lateral extent - as well as its manipulation have both been investigated since the first experiments on laser-driven ion acceleration using a variety of techniques from direct source imaging to knife-edge or mesh imaging.
In this publication, we present an experimental study in which laser ablation in two fluence regimes (low: F~0.6 J/cm², high: F~4 J/cm²) was applied to characterize and manipulate the hydro-carbon source layer. The high-fluence ablation in combination with a timed laser pulse for particle acceleration allowed for an estimation of the relevant source layer thickness for proton acceleration. Moreover, from these data and independently from the low-fluence regime, the lateral extent of the ion source layer became accessible.

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Permalink: https://www.hzdr.de/publications/Publ-25649


Enhancements in full-field PIXE imaging - large area elemental mapping with increased lateral resolution devoid of optics artefacts

Buchriegler, J.; Klingner, N.; Hanf, D.; Munnik, F.; Nowak, S. H.; Scharf, O.; Ziegenrücker, R.; Renno, A. D.; von Borany, J.

Abstract

The combination of a pnCCD-based pixel detector with a poly-capillary X-ray optics was installed and examined at the Helmholtz-Zentrum Dresden-Rossendorf. The set-up is intended for Particle Induced X-ray Emission imaging to survey the trace elemental composition of flat/polished geological samples. In the standard configuration a straight X-ray optics (20 µm capillary diameter) is used to guide the emitted photons from the sample towards the detector with nearly 70000 pixels. Their dimensions of 48×48 µm2 are the main limitation of the lateral resolution. This limitation can be bypassed by applying a dedicated sub-pixel algorithm to recalculate the footprint of the photon’s electron cloud in the detector. The lateral resolution is then mainly determined by the capillary’s diameter. Nevertheless, images are still superimposed by the X-ray optics pattern. The optics’ capillaries are grouped in hexagonal bundles resulting in a reduced transmission of X-rays in the boundary regions. This influence can be largely suppressed by combining a series of short measurements at slightly shifted positions using a precision stage and correcting the image-data for this shifting. The use of a sub-pixel grid for the image reconstruction allows a further increase of the spatial resolution. This approach of multi-frame super-resolution in combination with the sub-pixel correction algorithm is presented and illustrated with experimental data. Additionally, a flat-field correction is shown to remove the remaining imaging inhomogeneity caused by non-uniform X-ray transmission. The described techniques can be used for all X-ray spectrometry methods using an X-ray camera to obtain high quality elemental images.

Keywords: Color X-ray camera; full-field imaging; image stacking; multi-frame super-resolution; flat-field correction

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Permalink: https://www.hzdr.de/publications/Publ-25648


Road to micron resolution with a color X-ray camera – polycapillary optics characterization

Nowak, S. H.; Petric, M.; Buchriegler, J.; Bjeoumikhov, A.; Bjeoumikhov, Z.; von Borany, J.; Munnik, F.; Radtke, M.; Renno, A. D.; Reinholz, U.; Scharf, O.; Tilgner, J.; Wedell, R.

Abstract

In a color X-ray camera spatial resolution is achieved by means of a polycapillary optic conducting X-ray photons from small regions on a sample to distinct energy dispersive pixels on a CCD matrix. At present, the resolution limit of color X-ray camera systems can go down to several microns and is mainly restricted by pixel dimensions. The recent development of an efficient subpixel resolution algorithm allows a release from pixel size, limiting the resolution only to the quality of the optics. In this work polycapillary properties that influence the spatial resolution are systematized and assessed both theoretically and experimentally. It is demonstrated that with the current technological level reaching one micron resolution is challenging, but possible.

Keywords: color X-ray camera; polycapillary optics; lateral resolution

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Permalink: https://www.hzdr.de/publications/Publ-25647


Asymmetric spin-wave dispersion in ferromagnetic nanotubes induced by surface curvature

Otálora, J. A.; Yan, M.; Schultheiss, H.; Hertel, R.; Kákay, A.

Abstract

We present a detailed analytical derivation of the spin wave (SW) dispersion relation in magnetic nanotubes with magnetization along the azimuthal direction. The obtained formula can be used to calculate the dispersion relation for any longitudinal and azimuthal mode. The obtained dispersion is asymmetric for all azimuthal modes traveling along the axial direction. As reported in our recent publication [Phys. Rev. Lett. 117, 227203 (2016)], the asymmetry is a curvature-induced effect originating from the dipole-dipole interaction. Here, we discuss the asymmetry of the dispersion for azimuthal modes by analyzing the SW asymmetry deltaf (kz) = fn(kz) − fn(−kz), where fn(kz) is the eigenfrequency of a magnon with a longitudinal and azimuthal wave vectors, kz and n, respectively; and the dependence of the maximum asymmetry with the nanotube radius R. The analytical results are in perfect agreement with micromagnetic simulations. Furthermore, we show that the dispersion relation simplifies to the thin-film dispersion relation with in-plane magnetization when analyzing the three limiting cases: (i) kz = 0, (ii) kz>>1/R, and (iii) kz<<1/R. In the first case, for the zeroth-order modes the thin-film Kittel formula is obtained. For modeswith higher order the dispersion relation for the Backward-Volume geometry is recovered. In the second case, for the zeroth-order mode the exchange dominated dispersion relation for SW in Damon-Esbach configuration is obtained. For the case kz<<1/R, we find that the dispersion relation can be reduced to a formula similar to the Kalinikos-Slavin [J. Phys. C: Sol. State Phys. 19, 7013 (1986)] type.

Keywords: Spin waves; curvature; mangnonics

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-25646


TELBE: High-field high-repetition-rate photonics facility for coherent terahertz control of Matter

Wang, Z.; Deinert, J.-C.; Green, B.; Awari, N.; Chen, M.; Kovalev, S.; Gensch, M.

Abstract

The TELBE user facility at Helmholtz-Zentrum Dresden-Rossendorf is based on the new class of accelerator-driven terahertz (THz) radiation sources. Superradiant THz radiation is generated from relativistic electron bunches in a compact MeV level superconducting radiofrequency electron accelerator. Compared to the laser-based table-top THz sources with moderate repetition rates of a few kHz, the superradiant THz facility TELBE provides high repetition rates (quasi-cw) up to several 100 kHz, peak electric fields of 1 GV/m, and flexibility of tuning the THz pulse form. Time resolved experiments can be performed with time resolution down to 30 fs using the novel pulse-resolved diagnostics. We will present the results from first benchmarking THz control experiments, and discuss the possibility of various pump-probe experiments for friendly users, especially at low temperatures and in magnetic fields.

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  • Poster
    International Conference on Quantum Criticality and Novel Phases (QCNP 2017), 26.02.-01.03.2017, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-25645


Nanometer probing of ultrahigh intensity ultrashort pulse laser interaction with solid density plasmas, by Small Angle X-Ray Scattering using XFELs

Kluge, T.; Rödel, M.; Metzkes, J.; Pelka, A.; Laso Garcia, A.; Prencipe, I.; Hartley, N.; Nakatsutsumi, M.; Gutt, C.; Galtier, E.; Nam, I.; Lee, H. J.; Zacharias, M.; Garten, M.; Bussmann, M.; Zeil, K.; Rödel, C.; Mcbride, E.; Schramm, U.; Cowan, T. E.

Abstract

Nanometer probing of ultrahigh intensity ultrashort pulse laser interaction with solid density plasmas, by Small Angle X-Ray Scattering using XFELs

  • Lecture (Conference)
    2017 European XFEL Users' Meeting and Satellite Meetings, Satellite Meeting: Status of the HED science instrument & Meeting of the HIBEF user consortium, 24.01.2017, Hamburg, Deutschland
  • Invited lecture (Conferences)
    International Conference on Extreme Light, 06.-09.11.2017, Szeged, Ungarn
  • Lecture (others)
    Plasmaphysik Seminar GSI, 17.01.2017, Darstadt, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25644


SAXS on ultrashort laser pulse experiments

Kluge, T.; Pelka, A.; Metzkes, J.; Rödel, M.; Laso Garcia, A.; Prencipe, I.; Gutt, C.; Schramm, U.; Cowan, T. E.

Abstract

Nanometer probing of ultrahigh intensity short pulse laser interaction with solid density plasmas, by Small Angle X-Ray Scattering using XFELs

  • Lecture (Conference)
    High Intensity Laser Matter Science at The HED Instrument at The European XFEL, 05.-06.04.2017, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25643


Start-to-end simulations for photon interaction in ultra-high intensity short pulse laser experiments with solids

Kluge, T.; Burau, H.; Garten, M.; Grund, A.; Huebl, A.; Matthes, A.; Jung, F.; Widera, R.; Zacharias, M.; Fortmann-Grote, C.; Bussmann, M.

Abstract

EUCALL annual meeting poster

  • Poster
    EUCALL annual meeting 2017, 07.-09.06.2017, Grenoble, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-25642


The need for detailed scattering simulations for Small Angle X-Ray Scattering on laser driven solids

Thomas Kluge; Burau, H.; Garten, M.; Grund, A.; Huebl, A.; Matthes, A.; Jung, F.; Widera, R.; Zacharias, M.; Fortmann-Grote, C.; Bussmann, M.

Abstract

SIMEX progress report June 2017

  • Lecture (Conference)
    EUCALL annual meeting 2017, 07.-09.06.2017, Grenoble, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-25641


1‑(4‑[18F]Fluorobenzyl)-4-[(tetrahydrofuran-2-yl)methyl]piperazine: A Novel Suitable Radioligand with Low Lipophilicity for Imaging σ1 Receptors in the Brain

He, Y.; Xie, F.; Ye, J.; Deuther-Conrad, W.; Cui, B.; Wang, L.; Lu, J.; Steinbach, J.; Brust, P.; Huang, Y.; Lu, J.; Jia, H.

Abstract

We have designed and synthesized novel piperazine compounds with low lipophilicity as σ1 receptor ligands. 1-(4-Fluorobenzyl)-4-[(tetrahydrofuran-2-yl)methyl]piperazine (10) possessed a low nanomolar σ1 receptor affinity and a high selectivity toward the vesicular acetylcholine transporter (>2000-fold), σ2 receptors (52-fold), and adenosine A2A, adrenergic α2, cannabinoid CB1, dopamine D1, D2L, γ-aminobutyric acid A (GABAA), NMDA, melatonin MT1, MT2, and serotonin 5-HT1 receptors. The corresponding radiotracer [18F]10 demonstrated high brain uptake and extremely high brain-to-blood ratios in biodistribution studies in mice. Pretreatment with the selective σ1 receptor agonist SA4503 significantly reduced the level of accumulation of the radiotracer in the brain. No radiometabolite of [18F]10 was observed to enter the brain. Positron emission tomography and magnetic resonance imaging confirmed suitable kinetics and a high specific binding of [18F]10 to σ1 receptors in rat brain. Ex vivo autoradiography showed a reduced level of binding of [18F]10 in the cortex and hippocampus of the senescence-accelerated prone (SAMP8) compared to that of the senescence-accelerated resistant (SAMR1) mice, indicating the potential dysfunction of σ1 receptors in Alzheimer’s disease.

Permalink: https://www.hzdr.de/publications/Publ-25640


test20

Henrion, K.

Abstract

alles nur ein Test

  • AAPG Bulletin (2017)

Permalink: https://www.hzdr.de/publications/Publ-25639


Noble gas ion beams in materials science for future applications and devices

Belianinov, A.; Burch, M. J.; Kim, S.; Tan, S.; Hlawacek, G.; Ovchinnikova, O.

Abstract

Helium ion microscopy (HIM), enabled by a gas field ion source (GFIS), is an emerging imaging and nanofabrication technique compatible with many applications in materials science. The scanning electron microscope (SEM) has become ubiquitous in materials science for high-resolution imaging of materials. However, due to the fundamental limitation in focusing of electron beams, ion-beam microscopy is now being developed (e.g., at 20 kV the SEM beam diameter ranges from 0.5 to 1 nm, whereas the HIM offers 0.35 nm). The key technological advantage of the HIM is in its multipurpose design that excels in a variety of disciplines. The HIM offers higher resolution than the best available SEMs as well as the traditional gallium liquid-metal ion source (LMISs) focused ion beams (FIBs), and is capable of imaging untreated biological or other insulating samples with unprecedented resolution, depth of field, materials contrast, and image quality. GFIS FIBs also offer a direct path to defect engineering via ion implantation, three-dimensional direct write using gaseous and liquid precursors, and chemical-imaging options with secondary ion mass spectrometry. HIM covers a wide range of tasks that otherwise would require multiple tools or specialized sample preparation. In this article, we describe the underlying technology, present materials, relevant applications, and offer an outlook for the potential of FIB technology in processing materials.

Keywords: Helium Ion Microscopy; Nanofabrication; defect engineering; 2D materials; Focused Ion Beam Induced Deposition

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Permalink: https://www.hzdr.de/publications/Publ-25638


Disentangling magnetic order on nanostructured surfaces

Erb, D.; Schlage, K.; Bocklage, L.; Hübner, R.; Merkel, D. G.; Rüffer, R.; Wille, H.-C.; Röhlsberger, R.

Abstract

We present a synchrotron-based X-ray scattering technique which allows disentangling magnetic properties of heterogeneous systems with nanopatterned surfaces. This technique combines the nm-range spatial resolution of surface morphology features provided by Grazing Incidence Small Angle X-ray Scattering and the high sensitivity of Nuclear Resonant Scattering to magnetic order. A single experiment thus allows attributing magnetic properties to structural features of the sample; chemical and structural properties may be correlated analogously. We demonstrate how this technique shows the correlation between structural growth and evolution of magnetic properties for the case of a remarkable magnetization reversal in a structurally and magnetically nanopatterned sample system.

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Permalink: https://www.hzdr.de/publications/Publ-25637


Quantifying the relative availability of high-tech by-product metals – The cases of gallium, germanium and indium

Frenzel, M.; Mikolajczak, C.; Reuther, M. A.; Gutzmer, J.

Abstract

There are considerable concerns about the supply security of certain high-tech elements produced as by-products. To determine in how far these concerns are justified by the actual availability of these elements, we compare the supply potentials for three particularly relevant examples – gallium, germanium and indium – to current and historic production volumes. Our assessment is based on detailed estimates of the amounts extractable from various raw materials given contemporary market prices and technologies. While the estimate for gallium is taken from a previous publication, the estimate for germanium is recalculated from an earlier estimate of recoverable germanium in reserves and resources, and the estimate for indium is compiled as part of this article.

We find that the supply potentials of all three elements significantly exceed current primary production. However, the degree to which this is the case varies from element to element. While both the supply potentials of gallium and germanium are ~10 times higher than primary production, the supply potential of indium is ~3 times higher.

Differences also exist in historic growth trends, with indium showing the fastest growth rate of the utilised supply potential. This makes it the most likely of the three to reach its maximum production level in the future. Based on these considerations we propose a new quantitative indicator for the future availability of by-products, time-to-maximum extraction as a by-product (TMEB), and show its utility in discriminating between the different supply situations of the three by-product elements.

Keywords: Scarcity; Critical raw materials; Indium; Companion metals; By-products; Supply potential

Permalink: https://www.hzdr.de/publications/Publ-25636


PIConGPU Particle-in-Cell Simulations of Transient High Energy Density Plasmas

Huebl, A.; Kluge, T.; Garten, M.; Grund, A.; Pausch, R.; Widera, R.; Matthes, A.; Debus, A.; Vorberger, J.; Fortmann-Grote, C.; Chung, H.-K.; Bussmann, M.

Abstract

This talk shows the progress of PIConGPU on modeling transient high-energy density plasmas for the EUCALL annual workshop. We report on new features in PIConGPU, challenges in HPC-scale I/O for PIC simulations and how we interact with simex_platform and our approach for collisional-radiative non-LTE modeling within the scope of particle-in-cell.

Keywords: PIConGPU EUCALL non-LTE HPC I/O transient plasma processes

  • Lecture (Conference)
    EUCALL Annual Meeting 2017, 07.-09.06.2017, Grenoble, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-25635


Studying tracer metabolism by LC-MS: (+)-[18F]flubatine and (S)-[18F]fluspidine – two different radioligands showing similar metabolic pathways in vitro and in vivo

Ludwig, F.-A.; Fischer, S.; Smits, R.; Hoepping, A.; Houska, R.; Patt, M.; Hesse, S.; Wünsch, B.; Sabri, O.; Brust, P.; Steinbach, J.

Abstract

Objectives: Radiometabolites can affect PET imaging dramatically due to their expected different properties. Therefore identification of radiometabolites is an important step to understand the metabolic fate of a radioligand. The approach presented demonstrates how LC-MS supports in vitro experiments and contributes to explore the metabolic profile of two tracers recently studied in human brain [1, 2].
Methods: (+)-[18F]Flubatine ([18F]1) and (S)-[18F]Fluspidine ([18F]2) (Figure 1), as well as nonradioactive references were incubated with human liver microsomes (HLM) in presence of NADPH and/or activated glucuronic acid (UDPGA) at 37°C. Radiometabolite patterns were monitored by radio-HPLC and structures were identified by LC-MS of non-radioactive incubations using different MS-methods (EPI, MS3). Plasma (30 min p.i.) and urine (90 min p.i.) from human subjects receiving [18F]1 or [18F]2 during clinical studies were investigated and compared with results von microsomal incubations.
Results: During HLM incubations in presence of NADPH, mono-hydroxylation was predominant for both, 1 and 2, beside debenzylation of 2. In presence of UDPGA 1 and 2 underwent glucuronidation, but only after previous hydroxylation. Corresponding in vitro radiometabolites were detected by radio-HPLC and assigned regarding their structure. Samples obtained from humans showed high stability of both tracers, whereby [18F]1 (97.0% in plasma 30 min p.i, n=6) proved to be more stable than [18F]2 (85.3% in plasma 30 min p.i, n=3). However, hydroxylation and subsequent glucuronidation was found to be the major metabolic pathway of both tracers.
Conclusions: Using in vitro studies and LC-MS, in vivo radiometabolites could be identified. Beside high metabolic stability, [18F]1 and [18F]2 show similar major pathways, namely glucuronidation after previous hydroxylation.
Acknowledgements: Supported by the Helmholtz Validation Fund (HVF) and the German Research Foundation (DFG).
References: [1] Sattler et al. (2015), J Nucl Med, 56, suppl. 3, 1020; [2] Sattler et al. (2016), J Nucl Med, 57, suppl. 2, 1022.

Keywords: PET; LC-MS; Microsomes; Flubatine; Fluspidine; Metabolism; Fluorine-18

  • Lecture (Conference)
    XIV Turku PET symposium, 27.-30.5.2017, Turku, Finnland

Permalink: https://www.hzdr.de/publications/Publ-25633


Orthotopic Transplantation of Cancer Cells into Mice Lung Using a Stereotactic Technique

Aktar, R.; Bütof, R.; Tillner, F.; Baumann, M.; Krause, M.; Dietrich, A.

Abstract

Primary radiotherapy is the treatment of choice for patients with locally advanced non-small cell lung carcinoma where surgery is unable to perform. Orthotopic tumor models, where tumor material is transplanted into the corresponding organ of origin, are used in preclinical studies to predict the clinical efficacy of newly developed treatment options. For radiooncological research, orthotopic lung tumor models should have the characteristics of growing locally and spread in a manner that resembles the growth and metastasis of a real clinical situation.

In light of these respects, luciferases expressing human lung carcinoma cells (A549) were used for orthotopic transplantation. Different transplantation techniques were tested: (i) injection of small tumor pieces (< 1 mm) of subcutaneous source tumors, (ii) percutaneous injection of cell suspensions in matrigel between two ribs or (iii) stereotactic-guided injection of few microliters of cell suspensions with matrigel. Tumor development was imaged twice weekly by optical imaging using IVIS Spectrum and cone beam CT integrated in the Small-Animal Image-Guided Radiotherapy (SAIGRT) platform, developed in our institute. Tumor histology was analyzed via staining with hematoxylin and eosin and human origin of tumors were verified by a specific anti-human Ki-67 antibody. Our experiments revealed a multifocal, early metastatic spreading after percutaneous injection of cell suspensions while the transplantation of small tumor pieces lead to a defined tumor mass after quite a long period of time. In contrast, our new stereotactic approach resulted in early solitary lung lesions mimicking a clinical scenario which will allow us to start image-guided radiotherapy treatment at an appropriate time point.

In the future different lung carcinoma cell lines will be orthotopically transplanted using the stereotactic technique and corresponding growth and metastatic potential will be compared in order to improve the selection of models for preclinical radiooncological experiments.

  • Lecture (Conference)
    ERRS and GBS 2017, 17.-21.09.2017, Essen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25632


DOs and DON’Ts of applying for an ERC starting grant

Makarov, D.

Abstract

In this special open door Seminar at the FU Berlin I will address the following aspects:

•outline my Research Topic: flexible interactive electronics based on magnetic field sensors
•challenges of carrying out basic and applied research
•‘DOs’ and ‘DON’Ts’ of applying for an ERC starting grant, based on my personal experience

Keywords: shapeable magnetic field sensorics

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    Special Open Door Talk "Do's and Dont's of Appyling for an ERC Starting Grant" at the FU Berlin, 29.06.2017, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-25630


Flexible and ultrathin magnetic field sensorics

Makarov, D.

Abstract

Erst vor kurzem haben wir flexible Magnetoelektronik (Hall-Elemente und Magnetoresistive Sensoren) entwickelt. Die Kernidee der Technologie beruht auf der Kombination flexibler Polymermembranen und magnetisch hochempfindlicher metallischer Dünnschichten. Diese Synergie führt zu einzigartigen Eigenschaften und erlaubt die Gestaltung einer neuen Klasse von Magnetfeldsensoren mit einer neuartigen Funktionaltät der Verformbarkeit. Die Technologie erlaubt es, dass die magnetoelektronischen Elemente auch nach der Herstellung beliebige Formen durch Biegen, Verdrehen und Dehnen annehmen und somit auf gekrümmten Oberflächen integriert werden können.

Die formbare Magnetoelektronik weist zugleich mehrere kundenspezifische Vorteile hinsichtlich ereichbarer Sensorbauhöhen und –aktivflächen sowie Flexibilität im Vergleich zu konventioneller starrer Magnetfeldsensorik auf:

Verformbarkeit: Die Technologie erlaubt es, dass die magnetoelektronischen Elemente auch nach der Herstellung beliebige Formen durch Biegen, Verdrehen und Dehnen annehmen und somit auf gekrümmten Oberflächen integriert werden können.

Sensoraktivfläche: Es besteht die einzigartige Möglichkeit formbare magnetische Sensoren neben einer kleinflächigen Realisierung ebenso als grossflächige Sensoren, z. B. zur vorteilhaften Erfassung der mittleren magnetischen Flussdichte über eine planare oder beliebig gekrümmte Messoberfläche, kostengünstig herzustellen.

Geringe Bauhöhe: Unsere Technologieplatform ermöglicht Sensorbauhöhen von weniger als 150 μm. Das stellt eine Bauhöhereduktion von ca. 60% in Vergleich zu starrer Magnetfeldsensorik dar.

Keywords: flexible magnetic field sensors

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    12. Silicon Saxony Day, 20.06.2017, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-25629


Flexible und ultradünne Magnetfeldsensorik

Makarov, D.

Abstract

Neuartige magnetische Sensoren, die sich noch nach ihrer Herstellung beliebig verformen lassen, bieten entscheidende Vorteile gegenüber herkömmlichen in starrer Architektur. Sie können in kleinsten Luftspalten elektrischer Werkzeugmaschinen eingesetzt werden und so deren Leistungsfähigkeit deutlich erhöhen. Darüber hinaus ergeben sich neue, spektakuläre Anwendungen, wie z. B. „Internet of Things“.

Keywords: flexible magnetic field sensors

Involved research facilities

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  • Invited lecture (Conferences)
    Science Match: Future Technologies, 26.01.2017, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-25628


Flexible electronics: from interactive on-skin devices to in vivo applications

Makarov, D.

Abstract

The portable consumer electronics necessitates functional elements to be lightweight, flexible, and wearable [1-4]. The unique possibility to adjust the shape of the devices offered by this alternative formulation of the electronics provides vast advantages over the conventional rigid devices particularly in medicine and consumer electronics. There is already a remarkable number of available flexible devices starting from interconnects, sensing elements towards complex platforms consisting of communication and diagnostic components.
We developed shapeable magnetoelectronics [5] – namely, flexible [6-8], printable [9,10], stretchable [11,12] and even imperceptible [13] magnetosensitive large area elements, which were completely missing in the family of flexible electronics. The unique mechanical properties open up new application potentials for smart skins, allowing to equip the recipient with a “sixth sense” providing new experiences in sensing and manipulating the objects of the surrounding us physical as well as digital world [7,13]. On the other hand, we realized self-assembled compact tubular microchannels based on strain engineering [14] with integrated passive sensory elements [15-17] and communication antenna devices [18] for on-chip and bio-medical applications, e.g. smart implants [19,20].
Combining these two research directions carried out at different length scales into a single truly interdisciplinary topic opens up the novel field of smart biomimetics [20]. In this respect, we demonstrated mechanically and electrically active compact biomimetic microelectronics, which can serve as a base for realization of novel regenerative neuronal cuff implants with unmatched functionalities. The biomimetic microelectronics can mechanically adapt to and impact the environment possessing the possibility to assess, adopt and communicate the environmental changes and even stimulate the environment electrically.
In my talk, these recent developments will be covered.

[1] M. G. Lagally, MRS Bull., 32, 57 (2007).
[2] J. A. Rogers et al., Nature, 477, 45 (2011).
[3] S. Bauer et al., Adv. Mater., 26, 149 (2014).
[4] M. Kaltenbrunner et al., Nature, 499, 458 (2013).
[5] D. Makarov et al., Appl. Phys. Rev., 3, 011101 (2016).
[6] G. Lin, D. Makarov et al., Lab Chip, 14, 4050 (2014).
[7] M. Melzer, D. Makarov et al., Adv. Mater., 27, 1274 (2015).
[8] N. Münzenrieder, D. Makarov et al., Adv. Electron. Mater., 2, 1600188 (2016).
[9] D. Karnaushenko, D. Makarov et al., Adv. Mater., 27, 880 (2015).
[10] D. Karnaushenko, D. Makarov et al., Adv. Mater., 24, 4518 (2012).
[11] M. Melzer, D. Makarov et al., Adv. Mater., 27, 1333 (2015).
[12] M. Melzer, D. Makarov et al., Nano Lett., 11, 2522 (2011).
[13] M. Melzer, D. Makarov et al., Nat. Commun., 6, 6080 (2015).
[14] O. G. Schmidt et al., Nature, 410, 168 (2001).
[15] I. Mönch, D. Makarov et al., ACS Nano, 5, 7436 (2011).
[16] C. Müller, D. Makarov et al., Appl. Phys. Lett., 100, 022409 (2012).
[17] E. J. Smith, D. Makarov et al., Lab Chip, 12, 1917 (2012).
[18] D. D. Karnaushenko, D. Makarov et al., NPG Asia Materials, 7, e188 (2015).
[19] D. Karnaushenko, D. Makarov et al., Adv. Mater., 27, 6582 (2015).
[20] D. Karnaushenko, D. Makarov et al., Adv. Mater., 27, 6797 (2015).

Keywords: flexible magnetic field sensors; GMR effect; shapeable magnetoelectronics

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  • Invited lecture (Conferences)
    LII Zakopane School of Physics, 26.05.2017, Zakopane, Poland

Permalink: https://www.hzdr.de/publications/Publ-25627


ERC grant SMaRT at the Helmholtz-Zentrum Dresden-Rossendorf

Makarov, D.

Abstract

In this invited talk I presented the HZDR as a user facility. The activities of the FWIN-I Group was Reviewed. Beside the scientific part, I shared my experience in applying / handling the ERC starting grant.

Keywords: flexible electronics; ERC

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    Eastern Partnership PLUS Workshop “Science Connects”, 15.05.2017, Kyiv, Ukraine

Permalink: https://www.hzdr.de/publications/Publ-25626


Intelligent materials and devices

Makarov, D.

Abstract

In this invited talk I discussed the activities of the Group FWIN-I on flexible interactive electronics. The summary of the fabrication of mechanically flexible magnetic field sensors was given. The prospective application directions were outlined. The fundamental Background behind the electrical and magnetic Responses of curved magnetic thin films was given.

Keywords: curved magnetic thin films; flexible electronics; magnetic field sensors

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    Special workshop at the Institute of Mathematics, National Academy of Sciences of Ukraine, 14.05.2017, Kyiv, Ukraine

Permalink: https://www.hzdr.de/publications/Publ-25625


Prompt-gamma based range verification with a slit camera: Sensitivity and first clinical experiences

Richter, C.

Abstract

Overview of PGI slit camera activities in Dresden

  • Invited lecture (Conferences)
    ENLIGHT Annual Meeting 2017, 12.-13.06.2017, Aarhus, Danmark

Permalink: https://www.hzdr.de/publications/Publ-25624


Following our DREAMS (DREsden Accelerator Mass Spectrometry)

Merchel, S.; DREAMS-Team (S. Pavetich, G. Rugel, A. Scharf, R. Ziegenrücker,...); DREAMS-Users; DREAMS-Friends

Keywords: AMS

Involved research facilities

Related publications

  • Poster
    Workshop on Nuclear Astrophysics at the Dresden Felsenkeller, 26.-28.06.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25623


From Space to Earth to Accelerator Mass Spectrometry: Applications at Dresden AMS

Rugel, G.; Merchel, S.; DREAMS; Cooperation partners

Keywords: AMS; astrophysics

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Related publications

  • Poster
    Workshop on Nuclear Astrophysics at the Dresden Felsenkeller, 26.-28.06.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25622


Low-cost production of a beryllium-7 tracer from rainwater and purification: preliminary results

Querfeld, R.; Merchel, S.; Steinhauser, G.

Abstract

7Be with its relatively short half-life (53.22 days) is a possibly suitable radionuclide for radiotracer experiments. Low-level activities of natural 7Be can be found in rainwater and might be available as a tracer after radiochemical isolation. Herein, beryllium was first concentrated by evaporation of rainwater and/or iron(III) hydroxide co-precipitation. Afterwards, several separation schemes have been tested including various ion exchange resins in order to remove interfering other elements. Characterization was done by gamma spectrometry and inductively coupled plasma atomic emission spectrometry, respectively. With further optimizations of our methodology, rainwater may become a suitable low-cost and easily accessible 7Be tracer source.

Keywords: 7Be; tracer; gamma spectroscopy; Actinide resin; LN resin; Diphonix resin; DOWEX

Permalink: https://www.hzdr.de/publications/Publ-25621


Strain and particle size analysis in ion beam synthesized SiC nanoparticles using Raman scattering studies

Saravanan, K.; Jayalakshmi, G.; Panigrahi, B. K.; Hübner, R.

Abstract

We study the strain and particle size analysis of ion beam synthesized SiC nanoparticles (NPs) embedded in Si matrix using Raman and low-frequency Raman scattering (LFRS). 300 keV C+ ions with the fluence of 2 × 1017 ions/cm2 were implanted on Si substrate at three different substrate temperatures (300, 500 and 650 °C). Raman scattering analyses confirm the formation of 3C-SiC NPs in Si matrix. Relative strain in 3C-SiC NPs estimated from Raman scattering was found to decrease with increase of substrate temperature. The particle size distribution of 3C-SiC NPs was estimated from the signature of localized acoustic phonon modes observed in the low frequency region (ω<40cm-1) of LFRS spectra. The estimated particle size of the SiC is found to be in good agreement with the TEM analysis.

Keywords: Acoustic phonon modes; Ion beam synthesis; SiC nanoparticles; Strain

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Permalink: https://www.hzdr.de/publications/Publ-25620


Including Atomic Physics in Simulations of Transient Plasma Processes with PIConGPU & simex_platform

Huebl, A.; Garten, M.; Chung, H.-K.; Vorberger, J.; Kluge, T.; Bussmann, M.

Abstract

Particle-in-Cell (PIC) codes are the the working horses of computational modeling in plasma physics, as they describe even the most turbulent kinetic processes from first-principles. But great applicability comes with great computational demand, requiring leadership-scale HPC systems in order to model full 3D geometries with solid-density. This poster shows the open software architecture of the world's fastest PIC code PIConGPU which is addressing these demands for the community. With a blazingly short time-to-solution, GPU-powered high-performance computing opens unique opportunities for studying transient plasma processes, e.g. by including XFEL photon distributions from simex_platform. Trading speed for enhanced predictive capabilities, we including collisional-radiative non-LTE models from SCFLY into the electro-magnetic PIC cycle.

Keywords: PIC modeling transient plasma GPU laser-matter non-LTE collisional-radiative PIConGPU

  • Poster
    EUCALL Annual Meeting 2017, 07.-09.06.2017, Grenoble, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-25619


Kreislaufwirtschaft 4.0 - Was bedeutet die Digitalisierung für die kommunale Abfallwirtschaft?

Reuter, M. A.

Abstract

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure.

  • Invited lecture (Conferences)
    Ressourcenschutz und -effizienz: Die kommunale Abfallwirtschaft zwischen Politik und Potenzial / 2. Bundeskongress der kommunalen Abfallwirtschaft und Stadtreinigung 2017, 31.05.2017, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25618


Recycling 4.0

Reuter, M. A.

Abstract

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure.

  • Invited lecture (Conferences)
    Mitgliederversammlung des Landesverbandes der Recyclingwirtschaft Sachsen e.V. und der LVR-Entsorgergemeinschaft Sachsen e.V., 09.05.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25617


The effect of a Lorentz-force-driven rotating flow on the detachment of gas bubbles from the electrode surface

Weier, T.; Baczyzmalski, D.; Massing, J.; Landgraf, S.; Cierpka, C.

Abstract

Water electrolysis is a promising technique for energy conversion and is one of the key technologies to ensure an efficient and clean energy management in the future. However, the efficiency of this process is limited by overpotentials arising from - among other things - the high bubble coverage at the electrode surface. The influence of a magnetic field on the bubble behavior during electrolysis, in particular the bubble detachment from the electrodes, shows great potential for improving the efficiency of the process. In this study experiments and numerical simulations were carried out to investigate the effect of an electrode-normal magnetic field on the bubble detachment. Astigmatism Particle Tracking Velocimetry (APTV) was used to measure the magnetohydrodynamic (MHD) flow field around a magnetized sphere mimicking an electrolytic bubble. Complementary simulations gave further insight into the corresponding pressure field. The experimental and numerical results demonstrate that the pressure reduction formerly assumed to be responsible for the accelerated bubble detachment in the magnetic field is too weak to cause this effect. However, the flow over an arrangement of magnets was additionally measured by Particle Image Velocimetry (PIV), showing that the formation of bubble groups on the electrode surface gives rise to a stronger global flow which may have a substantial influence on the bubble behavior.

Keywords: electrolysis; magnetohydrodynamics

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Permalink: https://www.hzdr.de/publications/Publ-25616


Physical modelling of Czochralski crystal growth in horizontal magnetic field

Grants, I.; Pal, J.; Gerbeth, G.

Abstract

This study addresses experimentally the heat transfer, the temperature azimuthal non-uniformity and the onset of oscillations in a low temperature physical model of a medium-sized Czochralski Crystal growth process with a strong horizontal magnetic field (HMF). It is observed that under certain conditions the integral heat flux may decrease with increasing magnetic field strength at the same time as the flow velocity increases. The azimuthal non-uniformity of the temperature field in the melt near the crystal model rim is only little influenced by its rotation rate outside of a narrow range where the centrifugal force balances the buoyant one. The flow oscillation onset has been observed for two values of the HMF strength. Conditions of this onset are little influenced by the crystal rotation. The critical temperature difference of the oscillation onset considerably exceeds that of the Rayleigh–Bénard (RB) cell in a strong HMF.

Keywords: Fluid flows; Heat Transfer; Magnetic field assisted Czochralski method; Semiconducting materials

Permalink: https://www.hzdr.de/publications/Publ-25615


A round robin program of Master Curve evaluation using miniature C(T) specimens (comparison of T0 for a weld metal)

Yamamoto, M.; Carter, R.; Viehrig, H.-W.; Lambrecht, M.

Abstract

The Master Curve approach for the fracture toughness evaluation is expected to be a powerful tool to ensure the reliability of long-term used RPV steels. In order to get sufficient number of data for the Master Curve approach coexistent with the present surveillance program for RPVs, the utilization of miniature specimens, which can be taken from broken halves of surveillance Charpy specimens, is important. CRIEPI has been working on applying the miniature C(T) specimens (Mini-C(T)), whose dimensions are 4 x 10 x 9.6 mm, on the Master Curve fracture toughness evaluation. Miura (2010) had verified the basic applicability of Mini-C(T) specimens for typical Japanese RPV steels. Subsequently, an international round robin activity by Yamamoto (2012, 2013, 2014) assured the robustness of the testing procedure to the difference in testing machines or operators. Similar activity is being carried out for the weld metal materials and the basic applicability of Mini-C(T) was confirmed by Yamamoto (2015). The present paper describes the round robin activity for an un-irradiated weld metal, which is used for the weld filler of PRV plate steels. Four institutes are involved with the round robin tests and 78 fracture toughness data points in total were generated in conformity with ASTM E1921-10e1 (ASTM (2010)). All the participants successfully evaluated the valid reference temperature, To, with their own data set. The discrepancy among the 4 data sets was at the most 14 oC, which is considered as the acceptable scatter range specified in ASTM E1921-10e1. Weibull distribution of the 78 data points suggests that the tested material is in good agreement with the assumption of the Master Curve method, where the Weibull exponent is 4, the minimum fracture toughness is 20 MPa√m. From overall examination results, it was concluded that the miniature C(T) specimen can be used for the Master Curve evaluation of tested PRV weld metal.

Keywords: miniature specimens; fracture toughness; Master Curve; weld metal; reactor pressure vessel

  • Contribution to proceedings
    SMiRT-24 BEXCO, Division II, 20.-24.08.2017, Busan, Korea
    Transactions, SMiRT-24 BEXCO, Busan, Korea

Permalink: https://www.hzdr.de/publications/Publ-25614


[UO2Cl2(phen)2], a Simple Uranium(VI) Compound with a Significantly Bent Uranyl Unit (phen = 1,10-phenanthroline)

Schöne, S.; Radoske, T.; März, J.; Stumpf, T.; Patzschke, M.; Ikeda-Ohno, A.

Abstract

A simple synthesis based on UO2Cl2·n(H2O) and 1,10-phenanthroline (phen) resulted in the formation of a new uranyl(VI) complex [UO2Cl2(phen)2] (1), revealing a unique snub disphenoid coordination geometry around the uranium centre with significant bending of the robust linear arrangement of the uranyl (O─U─O) unit. Quantum chemical calculations on complex 1 indicated that the weak but distinct interactions between the uranyl oxygens and the adjacent hydrogens of phen molecules play an important role in forming the snub disphenoid geometry that fits to the crystal structure of 1, resulting in the bending the uranyl unit. The uranyl oxygens in 1 are highly activated as compared with those in the linear uranyl unit and, hence, complex 1 is anticipated to be one of the rare uranyl(VI) complexes with readily reactive uranyl oxygens.

Keywords: uranium; uranyl(VI); phenanthroline; n-donor; crystal structure; quantum chemical calculations

Permalink: https://www.hzdr.de/publications/Publ-25613


Dynamics of rectal balloon implant shrinkage in prostate VMAT: Influence on anorectal dose and late rectal complication risk

Vanneste, B.; van Wijk, Y.; Lutgens, L.; van Limbergen, E.; van Lin, E.; van de Beek, K.; Lambin, P.; Hoffmann, A.

Abstract

Background and Purpose:

To assess the effect of a shrinking rectal balloon implant (RBI) on the anorectal dose and complication risk during the course of prostate radiotherapy.

Material/Methods:

In 15 patients with localized prostate cancer an RBI was implanted. A weekly kilovolt cone-beam computed tomography (CBCT) scan was acquired to measure the dynamics of RBI volume and prostate-rectum separation. The absolute anorectal volume encompassed by the 75 Gy isodose (V75Gy) was calculated as well as the mean anorectal dose. The increase in risk of grade 2-3 late rectal bleeding (LRB) between the start and end of treatment was predicted.

Results:

A significant shrinkage of RBI volumes was observed, with an average volume of 70.4% of baseline at the end of the treatment. Although the prostate–rectum separation significantly decreased over time, it remained at least 1 cm. No correlation between mean anorectal dose and balloon deflation was found. No significant increase in V75Gy and increase in LRB risk over time was observed, except in one patient whose RBI had completely deflated in the third week of treatment.

Conclusions:

Despite significant decrease in RBI volume the high-dose rectal volume and the predicted LRB risk were unaffected due to a persistent spacing between the prostate and the anterior rectal wall.

Keywords: Prostate cancer; Radiotherapy; Rectal Balloon Implant; Volume stability; Rectal Dose; Rectal Toxicity

Permalink: https://www.hzdr.de/publications/Publ-25612


Bewertung von drei Verwertungsoptionen für das Fairphone und Übertragbarkeit auf weitere ressourcenrelevante Altgeräte

Reuter, M. A.

Abstract

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure.

  • Invited lecture (Conferences)
    2. Treffen AG 1 - Leiterplatten und ressourcenrelevante Bauteile, 19.05.2017, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25611


Structural transformations in two-dimensional transition-metal dichalcogenide MoS₂ under electron beam: insights from first-principles calculations

Kretschmer, S.; Komsa, H.-P.; Bøggild, P.; Krasheninnikov, A. V.

Abstract

The polymorphism of two-dimensional (2D) transition metal dichalcogenides (TMDs) and different electronic properties of the polymorphs make TMDs particularly promising materials in the context of the applications in electronics. Recently, local transformations from the hexagonal H to trigonal distorted T’ phase in 2D MoS₂ have been induced by electron irradiation [Nat. Nanotech. 9 (2014) 391], but the mechanism of the transformations remains elusive. Using density functional theory calculations, we study the energetics of the stable and metastable phases of 2D MoS₂ when additional charge, mechanical strain and vacancies are present. We also investigate the role of finite temperatures, which appear to be critical for the transformations. Based on the results of our calculations, we propose an explanation for the beam-induced transformations which are likely promoted by charge redistribution in the monolayer due to electronic excitations combined with formation of vacancies under electron beam and build-up of the associated mechanical strain in the sample. As this mechanism should be relevant to other 2D TMDs, our results provide hints for further development and optimization of electron-beam-mediated engineering of the atomic structure and electronic properties of 2D TMDs with sub-nanometer resolution.

Keywords: 2D materials; transition-metal dichalcogenides; phase transition; electron beam; first-principles calculations

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Permalink: https://www.hzdr.de/publications/Publ-25610


Coupling and stability of interfacial waves in liquid metal batteries

Horstmann, G. M.; Weber, N.; Weier, T.

Abstract

Liquid metal batteries (LMBs) are discussed today as a cheap grid scale energy storage, as required for the deployment of fluctuating renewable energies. LMBs incorporate stratified three-layer fluid systems consisting of two liquid metal electrodes separated by a thin molten salt electrolyte (see sketch below). Due to the large electrical conductivities of the liquid metals, LMBs are highly susceptible to become unstable by interactions of induced or external magnetic fields with internal cell currents. Several different types of instabilities have been identified as to be crucial for the LMB operation. Besides the Tayler instability and electrovortex flows, the metal pad roll (MPR) instability, originally known from aluminium reductions cells (ARCs), emerged as a key instability mechanism capable to cause short-circuits by exciting interfacial gravity-capillary waves. The MPR instability can be induced only by the interaction of a homogeneous vertical magnetic field with horizontal compensation currents arising due to small perturbations of the interfaces. While this mechanism is well understood in the case of ARCs, in LMBs an additional interface is present that may strongly influence the global stability depending on several parameters. Both interfaces can be closely coupled for thin salt-layers such that they both may excite each other and may be connected by different oscillating modes. The analysis of the coupling behavior is the main target of this study.
As the main part of this talk I will present an analytical analysis using linear wave theory describing coupled gravity-capillary waves enclosed in cylindrical containers. We have derived a fourth-order dispersion relation containing two different coupling modes. Further, we found that the global coupling behavior can be completely described by only two dimensionless parameters. On this basis, we suggest a coupling criterion predicting for which parameter regimes both interfaces can be considered as to be fully decoupled such that two-layer stability analysis becomes sufficient. Our study is further accompanied by both numerical simulations and experiments. For highly coupled cases we discovered different kinds of interface displacements not known from ARCs.
Some of the found states cannot be explained by the MPR instability mechanism alone and probably involve some new physical aspects.

Keywords: Liquid Metal Battery; MHD; Metal Pad Roll Instability; Wave Coupling

  • Lecture (Conference)
    International workshop on liquid metal battery fluid dynamics (LMBFD2017), 16.-17.05.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25608


Analysing methods of animal irradiation experiments with deviations from prescribed dose

Beyreuther, E.; Eger Passos, D.; Karsch, L.; Löck, S.; Pawelke, J.

Abstract

Introduction: The development of new radiotherapy technologies is a long time process which requires proving the general concept although clinical requirements with respect to beam quality and controlled dose delivery may not yet be fulfilled. Exemplarily, the necessary radiobiological experiments with laser-accelerated ion beams, which promise to compact ion radiotherapy facilities, are challenged by low particle energy and fluctuating beam intensities delivered by currently available laser systems. The first issue was handled by establishing a small tumour model on mouse ear that allows full penetration by ~25 MeV proton beams [1], whereas the latter, i.e. the subsequent deviations of the delivered from the prescribed dose, should be considered mathematically.

Methods: Based on tumour growth data and dose values obtained in a preceding in vivo trial comparing the biological efficacy of laser-driven and conventional LINAC electrons [2], different mathematical approaches to determine corresponding dose-response relationships were compared. During this experiment, the beam intensity fluctuations were not fully gathered by online dosimetry, which results in deviations of more than 10 % from scheduled dose as measured by retrospective absolute film dosimetry. Instead of classical averaging-per-dose point, which excludes animals with high dose deviations, multivariate linear regression, Cox regression and a Monte Carlo based approach were tested as alternatives to include all animals in statistical analysis.

Results: The application of different mathematical approaches to the same set of experimental tumour growth data and dose values led to similar results, revealing a comparable radiobiological efficacy of laser-driven and conventional LINAC electrons. Although the inclusion of those animals that were previously excluded because of more than 10% dose deviation did not change the experimental conclusion, the new mathematical approaches allowed for including all animals in the analysis. Comparing the different approaches, multivariate linear regression and Cox regression were considered as most feasible for future analysis, since they were already implemented in commercial statistical software, like SPSS (IBM).

Conclusion: The previously established small animal tumour model on mouse ear [1] together with the recently tested regression methods enable the investigation and evaluation of beams at new accelerators relative to their conventional equivalents despite their still limited beam stability, like laser-driven particle beams. The tested mathematical approaches allow for increasing the number of animals in analysis and therewith reduce the total number of animals in experiment with respect to the 3R of animal experimentation.

Acknowledgement: The work was supported by the German Government, Federal Ministry of Education and Research, grant nos. 03ZIK445 and 03Z1N511.

[1] Beyreuther et al. An optimized small animal tumour model for experimentation with low energy protons. PLOS One,2017; 12: e0177428.
[2] Oppelt et al. Comparison study of in vivo dose response to laser-driven versus conventional electron beam. Radiat Environ Biophys, 2015; 54:155-166.

  • Contribution to proceedings
    ERRS & GBS 2017, 17.-21.09.2017, Essen, Germany
  • Lecture (Conference)
    ERRS & GBS 2017, 17.-21.09.2017, Essen, Germany

Permalink: https://www.hzdr.de/publications/Publ-25607


Dual-energy CT based proton range prediction in head and pelvic tumor patients

Wohlfahrt, P.; Möhler, C.; Stützer, K.; Greilich, S.; Richter, C.

Abstract

Background and Purpose:

To reduce range uncertainty in particle therapy, an accurate computation of stopping-power ratios (SPRs) based on computed tomography (CT) is crucial. Here, we assess range differences between the state-of-the-art CT-number-to-SPR conversion using a generic Hounsfield look-up table (HLUT) and a direct patient-specific SPR prediction (RhoSigma) based on dual-energy CT (DECT) in 100 proton treatment fields.

Material and Methods:

For 25 head-tumor and 25 prostate-cancer patients, the clinically applied treatment plan, optimized using a HLUT, was recalculated with RhoSigma as CT-number-to-SPR conversion.
Depth-dose curves in beam direction were extracted for both dose distributions in a regular grid and range deviations were determined and correlated to SPR differences within the irradiated volume.

Results:

Absolute (relative) mean water-equivalent range shifts of 1.1mm (1.2%) and 4.1mm (1.7%) were observed in the head-tumor and prostate-cancer cohort, respectively. Due to the case dependency of a generic HLUT, range deviations within treatment fields strongly depend on the tissues traversed leading to a larger variation within one patient than between patients.

Conclusions:

The magnitude of patient-specific range deviations between HLUT and the more accurate DECT-based SPR prediction is clinically relevant. A clinical application of the latter seems feasible as demonstrated in this study using medically approved systems from CT acquisition to treatment planning.

Keywords: dual-energy CT; range uncertainty; proton therapy

Permalink: https://www.hzdr.de/publications/Publ-25606


Sensitivity of a prompt-gamma slit-camera to detect range shifts for proton treatment verification

Nenoff, L.; Priegnitz, M.; Janssens, G.; Petzoldt, J.; Trezza, A.; Smeets, J.; Pausch, G.; Richter, C.

Abstract

Background and Purpose: Prompt-gamma imaging (PGI) was recently applied successfully in first clinical patient treatments in pencil beam scanning (PBS) and double scattering (DS). Still, systematic evaluations on its capability in clinical conditions are desirable. Here, the performance of the slit-camera is systematically assessed in well-defined error scenarios using realistic treatment deliveries to an anthropomorphic phantom.
Materials and Methods: The sensitivity to detect global and local range shifts with the slit camera was investigated in PBS and DS irradiations of a head phantom. For PBS, measured PGI information for shifted geometries was compared spot-wise with either simulated or measured un-shifted PGI-information to evaluate the sensitivity to detect deviations from the treatment plan and interfractional shifts, respectively.
Results: Deviations from the treatment plan can be detected with an accuracy of 1.5 and 3 mm for global and local shifts in PBS, respectively. Interfractional comparisons are more affected by noise in the measurements. Evaluation of the average PGI signal of the whole field allows the detection of global shifts also in DS mode.
Conclusions: PGI-based detection of global and local range shifts under clinical conditions is possible. Especially for PBS treatments, both high sensitivity and high accuracy in shift detection were found.

Keywords: range verification; prompt gamma imaging; slit camera; proton therapy; PGI

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Permalink: https://www.hzdr.de/publications/Publ-25605


Experimental setup to measure magnetic field effects of proton dose distributions: simulation study

Schellhammer, S. M.; Oborn, B.; Lühr, A.; Gantz, S.; Bussmann, M.; Hoffmann, A. L.

Abstract

Background and Purpose: As an initial step towards MR-integrated proton therapy, a setup is introduced capable to measure thedose deposited by a proton beam within a magnetic field in tissue-equivalent material. Simulations are performed predicting the experimental outcome and radiation-induced risk effects on the magnet.
Material and Methods: The setup comprises proton pencil beams (80-180 MeV; Ø10 mm) passing through a transverse magnetic field of a permanent dipole magnet (0.95 T) while being stopped inside a PMMA phantom. Using a combined Monte Carlo and finite-element model validated by reference measurements of magnetic flux density, depth-dose distributions and beam profiles, 2D dose distributions of the central plane are simulated.
Depth-dose curves and beam trajectories are extracted. A worst-case estimate of radioactivation and demagnetization of the magnet is made.
Results: The model shows excellent agreement with the reference measurements. Mean dose to the magnets is below 2 μGy, and the initial activation below 12 kBq for a dose of 1 Gy in the film. The predicted deflection of the Bragg peak ranges from 1 mm to 9 mm.
Conclusions: The magnetic field induced beam deflections are measurable with the presented setup and radiation-induced magnet damage is expected to be manageable. This demonstrates the feasibility of a benchmarking experiment.

Keywords: proton therapy; MR-guided radiotherapy; beam deflection; dose measurement; Monte Carlo simulation

Permalink: https://www.hzdr.de/publications/Publ-25604


Melanoma Brain Metastases

Brütting, J.; Rauschenberg, R.; Troost, E. G. C.; Meier, F.; Garzarolli, M.

Abstract

The majority of melanoma patients with metastatic disease stage IV is also affected by brain metastases, which are the main cause of death. If there is suspicion of brain metastases, staging diagnostics including cranial magnetic resonance imaging (cMRI) and a neurological examination are indicated. Prognostic factors, such as the number and symptoms of brain metastases, serum LDH and S100, existence of extracerebral metastases and ECOG status, should be considered in treatment planning. In addition, therapeutic interventions should be based on an interdisciplinary and multimodal approach. In case of a single brain metastasis, treatment by neurosurgical resection or stereotactic radiotherapy is standard of care. Until recently, the sole option for controlling brain metastases was local treatment. However, the spectrum of therapies has significantly expanded by approval of effective immune checkpoint (CTLA-4 and PD-1 antibody) and targeted therapies (BRAF and MEK inhibitors). In case of multiple symptomatic brain metastases, palliative whole-brain radiotherapy is used although there is no significant prolongation of overall survival (OS) but only some improvement of neurological symptoms and quality of life. Corticosteroids and anticonvulsants are indicated for increased intracranial pressure and epileptic seizures. New treatment options in melanoma with brain metastasis such as PD-1 antibodies and several combination strategies (e.g. ipilimumab plus nivolumab, BRAF inhibitors plus MEK inhibitors, or stereotactic radiotherapy plus immune or targeted therapy) will be evaluated in ongoing clinical trials.

Permalink: https://www.hzdr.de/publications/Publ-25603


Modification of structural and magnetic properties in Fe/Pt (111)-oriented multilayers with ion beam irradiation

Marynowska, A.; Misiuna, P.; Lewińska, S.; Dynowska, E.; Wawro, A.; Ślawska-Waniewska, A.; Böttger, R.; Fassbender, J.; Baczewski, L. T.

Abstract

This paper reports on structural and magnetic properties changes that occur after irradiation of Fe/Pt (1 1 1) multilayers with Ne+ ions. Multilayer samples of Al2O3 (0 0 0 1)/Pt 100 Å/(Fe X Å/Pt X Å)n/Pt 100 Å structure with different individual layer thickness X (5 or 10 Å) and different number of bilayers n (5, 10 or 15) were irradiated with Ne+ ions of 10 to 25 keV energy and 1 × 1014 ÷ 1 × 1016 ions cm−2 dose range at room temperature. Irradiation parameters were estimated a priori using Tridyn software. As-deposited samples revealed presence of sharp interfaces. Structural properties changes were investigated using symmetrical and asymmetrical X-ray diffraction methods and magnetic properties changes were examined using vibrating sample magnetometer. Ion beam induced mixing of multilayers resulted in formation of disordered face centered cubic (fcc) FePt alloys of two different compositions (quasi-50:50 in the initial multilayer volume and Pt-rich in initial cover-layer volume). Non-regular changes in magnetic properties after ion irradiation were observed whilst retaining in-plane orientation of magnetization easy axis.

Keywords: Magnetic metallic thin films; Multilayers; Magnetic and structural properties; Ion irradiation

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Permalink: https://www.hzdr.de/publications/Publ-25602


Local formation of InAs nanocrystals in Si by masked ion implantation and flash lamp annealing

Rebohle, L.; Wutzler, R.; Prucnal, S.; Hübner, R.; Böttger, R.; Georgiev, Y. M.; Erbe, A.; Helm, M.; Skorupa, W.

Abstract

The integration of high-mobility III-V compound semiconductors emerges as a promising route for Si device technologies to overcome the limits of further down-scaling. In this work we investigate the possibilities to form InAs nanocrystals in a thin Si layer at laterally defined positions with the help of masked ion beam implantation and flash lamp annealing. In detail, after thinning of the device layer of a SOI wafer a cladding layer was deposited and patterned by electron beam lithography in order to serve as an implantation mask. The wafer was subsequently implanted with As and In, followed by flash lamp annealing leading to the formation of InAs nanocrystals in the implanted areas. The structures were investigated by Raman spectroscopy, scanning and transmission electron microscopy as well as energy-dispersive X-ray spectroscopy. Depending on the size of the implantation window, several, one or no nanocrystal is formed. Finally, the perspectives for using this technique for the local modification of Si nanowires are discussed.

Keywords: Blitzlampenausheilung; Ionenimplantation; Elektronstrahllithographie; InAs Nanokristalle; flash lamp annealing; ion implantation; electron beam lithography; InAs Nanocrystals

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  • Lecture (Conference)
    EMRS Spring Meeting, 21.-26.05.2017, Strasbourg, France

Permalink: https://www.hzdr.de/publications/Publ-25599


Evidence for self-organized formation of logarithmic spirals during explosive crystallization of amorphous Ge:Mn layers

Bürger, D.; Baunack, S.; Thomas, J.; Oswald, S.; Wendrock, H.; Rebohle, L.; Schumann, T.; Skorupa, W.; Blaschke, D.; Gemming, T.; Schmidt, O. G.; Schmidt, H.

Abstract

Logarithmic spirals are found on different length scales in nature, e.g. in nautilus shells, cyclones, and galaxies. The underlying formation laws can be related with different growth mechanisms, pressure gradients, and density waves. Here we report on the self-organized formation of symmetric logarithmic crystallization spirals in a solid material on the micrometer length scale, namely in an amorphous Ge:Mn layer on a Ge substrate. After exposure to a single light pulse of a flash lamp array, the Ge:Mn layer is crystallized and reveals a partially rippled surface and logarithmic microspirals. Finally, we present a model describing the formation of the crystallization spirals by directional explosive crystallization of the amorphous Ge:Mn layer which is triggered by the flash lamp light pulse.

Keywords: Logarithmische Spiralen; Selbstorganisation; Explosivkristallisation; Blitzlampenausheilung; logarithmic spirals; self-organization; explosive crystallization; flash lamp annealing

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Permalink: https://www.hzdr.de/publications/Publ-25598


Photons, protons or carbon ions for stage I non-small cell lung cancer - results of the multicentric ROCOCO in silico study

Wink, K. C. J.; Roelofs, E.; Simone, C. B.; Dechambre, D.; Santiago, A.; van der Stoep, J.; Dries, W.; Smits, J.; Avery, S.; Ammazzalorso, F.; Jansen, N.; Jelen, U.; Solberg, T.; de Ruysscher, D.; Troost, E. G. C.

Abstract

Purpose: To compare dose to organs at risk (OARs) and dose-escalation possibility for 24 stage I nonsmall cell lung cancer (NSCLC) patients in a ROCOCO (Radiation Oncology Collaborative Comparison) trial.
Methods: For each patient, 3 photon plans [Intensity-modulated rad 5 iotherapy (IMRT), volumetric modulated arc therapy (VMAT) and CyberKnife], a double scattered proton (DSP) and an intensitymodulated carbon-ion (IMIT) therapy plan were created. Dose prescription was 60Gy (equivalent) in 8 fractions.
Results: The mean dose and dose to 2% of the clinical target volume (CTV) were lower for protons 10 and ions compared with IMRT (p<0.01). Doses to the lungs, heart, and mediastinal structures were lowest with IMIT (p<0.01), doses to the spinal cord were lowest with DSP (p<0.01). VMAT and CyberKnife allowed for reduced doses to most OARs compared with IMRT. Dose escalation was possible for 8 patients. Generally, the mediastinum was the primary dose-limiting organ.
Conclusion: On average, the doses to the OARs were lowest using particles, with more homogenous 15 CTV doses. Given the ability of VMAT and CyberKnife to limit doses to OARs compared with IMRT, the additional benefit of particles may only be clinically relevant in selected patients and thus should be carefully weighed for every individual patient.

Keywords: stage I NSCLC; radiotherapy; particle therapy; in silico planning study; multicentric trial

Permalink: https://www.hzdr.de/publications/Publ-25597


Testing the NURESIM platform on a PWR main steam line break benchmark

Kliem, S.; Kozmenkov, Y.; Hadek, J.; Perin, Y.; Fouquet, F.; Bernard, F.; Sargeni, A.; Cuervo, D.; Sabater, A.; Sanchez-Cervera, S.; Garcia-Herranz, N.; Zerkak, O.; Ferroukhi, H.; Mala, P.

Abstract

Within the NURESAFE project, a main steam line break benchmark has been defined and solved by codes integrated into the European code platform NURESIM. The paper describes the results of the calculations for this benchmark. Six different solutions using different codes and code systems are provided for the comparison. The quantitative differences in the results are dominated by the differences in the secondary system parameters during the depressurization. The source of these differences comes mainly from the application of different models for the two-phase leak flow available in the system codes. The use of two different thermal hydraulic system codes influences the results more than expected when the benchmark was created. The codes integrated into the NURESIM platform showed their applicability to a challenging transient like a main steam line break.

Permalink: https://www.hzdr.de/publications/Publ-25595


Variation in platinum group mineral and base metal sulfide assemblages in the Lower Group chromitites of the western Bushveld Complex, South Africa

Bachmann, K.; Osbahr, I.; Tolosana-Delgado, R.; Chetty, D.; Gutzmer, J.

Abstract

The Lower Group chromitites of the Bushveld Igneous Complex are mined for chromite as a primary product. The recovery of platinum group elements and base metals (Ni, Cu) as by-products has the potential to add value to the chromite resources. This study focuses on the LG-6 and LG-6A chromitite seams at the Thaba mine located on the western limb of the Bushveld Complex. Platinum group minerals and base-metal sulfides are studied by mineral liberation analysis and electron microprobe analysis to define distinct assemblages and to evaluate the potential for beneficiation. Based on the results two distinct major mineral assemblages are defined: The first assemblage is rich in platinum group element-sulfides, along with variable proportions of malanite/cuprorhodsite and alloys of Fe and Sn. The associated base metal sulfides are dominated by chalcopyrite, pentlandite, but also pyrite and subordinate millerite/violarite. Associated silicates are mainly primary magmatic orthopyroxene and plagioclase. The second assemblage is rich in platinum group element-sulfarsenides and -arsenides and -alloys of Sb and Bi, which are associated with a base metal sulfide assemblage dominated by pentlandite and Co-rich pentlandite. Silicates in this assemblage are marked by an abundance of alteration minerals, such as talc, serpentine and/or carbonates, which are closely associated with the platinum group minerals. Geostatistical evaluation reveals that these two mineral assemblages are not attributable to the origin of samples from different chromitite seams, but document the effects of pervasive hydrothermal alteration. Alteration evidently had similar effects on the different chromitite seams. Occurrence and distribution of these two characteristic assemblages has important implications for beneficiation. Assemblages rich in platinum group element-sulfides associated with base metal sulfides are known to respond well to flotation, different to alteration assemblages rich in arsenides and alloys. The nature of the gangue minerals will also impact platinum group mineral recovery as high phyllosilicate abundances, such as those noted in the alteration assemblage may cause problems during flotation and lead to poor recoveries.

Keywords: EPMA; SEM-based image analysis; ANOVA; Cluster Analysis; PGM; Thaba Mine

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Permalink: https://www.hzdr.de/publications/Publ-25594


New solar-selective CSP receiver coatings studied by environmental in situ methods

Krause, M.; Wenisch, R.; Heras, I.; Lungwitz, F.; Janke, D.; Guillén, E.; Erbe, A.; Gemming, S.; Escobar Galindo, R.

Abstract

The development of solar-selective CSP receiver coatings with high-temperature and environmental stability requires new concepts of design and in operando monitoring. Solar receiver tubes are a key component of solar thermal power plants. The increase of their operation temperature from today’s maximum of 550°C to about 800°C could increase the CSP efficiency by approximately 15 to 20% and improve the competiveness of this technology compared to other ones of carbon-free electricity generation. Potential alternatives to fast degrading state-of-the-art pigment paint receiver tube coatings are based on refractive metal carbides, nitrides, and oxides because of their high thermal stability and oxidation resistance. New types of solar-selective coatings were studied in situ at temperatures of up to 830°C by Rutherford backscattering spectrometry, Raman spectroscopy, and spectroscopic ellipsometry within a cluster tool. They include carbon- and oxynitride-absorber based multilayers as well as a solarselective transmitter based on a transparent conductive oxide.

Financial support by the EU, grant No. 645725, project FRIENDS2, and the HGF via the W3 program (S.G.) is gratefully acknowledged.

Keywords: Concentrated solar power; in situ analysis; cluster tool; solar-selective coatings

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  • Invited lecture (Conferences)
    12th Pacific Rim Conference on Ceramic and Glass Technology including Glass & Optical Materials Division Meeting 2017, 21.-26.05.2017, Waikoloa, USA

Permalink: https://www.hzdr.de/publications/Publ-25592


Design of Solar Selective Coatings Based on Aluminium Titanium AlTi(OxN1-x) Oxynitrides for High-Temperature CSP Applications

Heras, I.; Krause, M.; Lungwitz, F.; Rincon, G.; Alcon-Camas, M.; Azkona, I.; Guillén, E.; Escobar-Galindo, R.

Abstract

Aluminium titanium oxynitrides were studied as candidate materials for high temperature solar-selective coatings due to their excellent stability and their tuneable optical behaviour. A set of individual AlyTi1-y(OxN1-x) layers with different oxygen content was prepared by cathodic vacuum arc (CVA) deposition. The composition, morphology, phase structure and microstructure of the films were characterized by elastic recoil detection (ERD), scanning and transmission electron microscopy and X-ray diffraction.

Keywords: Concentrated solar power; solar-selective coatings; optical simulation

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  • Lecture (Conference)
    2017 MRS Spring Meeting & Exhibit, 17.-21.04.2017, Phoenix, USA

Permalink: https://www.hzdr.de/publications/Publ-25591


Verlängerte Hirnmetastasenkontrolle bei geringer Toxizität nach einer Radiatio (SRS/WBR) in Kombination mit einer Systemtherapie bei zerebral metastasierten Melanompatienten

Rauschenberg, R.; Bruns, J.; Daubner, D.; Garzarolli, M.; Beissert, S.; Linn, J.; Troost, E. G. C.; Meier, F.

Abstract

Das mediane Überleben von Patienten mit Hirnmetastasen des malignen Melanoms beträgt ohne Therapie 2 Monate [1]. Neben etablierten lokalen Behandlungsmodalitäten wie der Resektion, stereotaktischen Radiatio (SRS) oder Ganzhirnbestrahlung (WBR) stehen innovative Immuntherapien (CTLA-4- und PD-1-Antikörper) und zielgerichtete Behandlungen (BRAF- +/- MEK-Inhibitoren) zur Verfügung. Prospektive Studiendaten zur Wirksamkeit und Toxizität der Kombination dieser Systemtherapien mit einer Bestrahlung stehen aus.
Wir führten eine retrospektive Datenanalyse der im Zeitraum von März 2014 bis März 2016 im Universitätsklinikum Dresden behandelten Melanompatienten mit Hirnmetastasen durch, die eine zerebrale Bestrahlung und bis zu 5 Wochen davor, danach oder währenddessen eine der oben genannten Systemtherapien erhalten hatten. Ein klinisches Follow-Up wurde monatlich durchgeführt – zusätzlich zum vierteljährlichen Staging (Schädel-MRT/CT). Eine detaillierte neuroradiologische Auswertung erfolgte. Primäre Endpunkte der Studie waren Toxizität, Hirnmetastasenkontrolle und Gesamtüberleben.
Insgesamt erhielten 22 Patienten mit zerebral metastasiertem Melanom eine SRS (10) oder WBR (12) plus 5 Wochen davor, danach oder währenddessen eine Systemtherapie mit BRAF-/MEK-Inhibitoren (5) oder CTLA-4-/PD-1-Antikörpern (17). Abgesehen von Übelkeit (1) wurden keine CTCAE-Grad 3/4-Nebenwirkungen der Bestrahlung beobachtet. Insbesondere die Rate an Radionekrosen und Einblutungen war nach Kombinationstherapie im Vergleich zur alleinigen SRS nicht erhöht. 6 Monate nach der Radiatio waren bei 75 % (SRS) beziehungsweise 70 % der Patienten (WBR) keine neuen Hirnmetastasen aufgetreten. Kaplan-Meier-Schätzungen ergaben ein medianes Gesamtüberleben mit Hirnmetastasen von 20 (SRS) respektive 14 Monaten (WBR).
Die Kombination einer zerebralen Bestrahlung mit einer Systemtherapie wurde gut toleriert. Die retrospektiven Daten sprechen für eine Verlängerung der Hirnmetastasenkontrolle sowie des Überlebens und propagieren prospektive Studien. Aktuell wird die retrospektive Analyse in 15 weiteren deutschen Hauttumorzentren durchgeführt.
[1] Fife KM et al (2004) Determinants of outcome in melanoma patients with cerebral metastases. J Clin Oncol 22(7):1293-1300

Keywords: SRS; WBRT; CTLA-4; PD-1

  • Contribution to proceedings
    27. Deutschen Hautkrebskongress, 21.-23.09.2017, Mainz, Deutschland
    Journal der Deutschen Dermatologischen Gesellschaft 15, Suppl. 3, 11-12

Permalink: https://www.hzdr.de/publications/Publ-25590


Visual observation and charge/discharge behavior of liquid metal cells

Nimtz, M.; Landgraf, S.

Abstract

Over the last years, several experiments on liquid metal battery (LMB) materials and different electrode and electrolyte systems were performed at HZDR. The presentation will give an overview on experimental equipment and setup, preparation steps of cell and container materials and cell charge/discharge behaviour. Main focus lies on the visual observation of several chemical incompatibilities and/or mechanical processes in LMB cells and liquid metal - molten salt - container material systems.

Keywords: liquid metal battery; molten salts

  • Lecture (Conference)
    International Workshop on Liquid Metal Battery Fluid Dynamics (LMBFD2017), 16.-17.05.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25589


X-Ray Diffraction and X-Ray Spectroscopy Studies of Cobalt-Doped Anatase TiO2:Co Nanopowders

Mesilov, V. V.; Galakhov, V. R.; Gubkin, A. F.; Sherstobitova, E. A.; Zakharova, G. S.; Uimin, M. A.; Yermakov, A. E.; Kvashnina, K. O.; Smirnov, D. A.

Abstract

Cobalt-doped anatase Ti0.97Co0.03O2 nanopowders with a particle size of about 100 °A were produced by a microwave-hydrothermal method. The obtained samples were characterized by means of X-ray diffraction, X-ray absorption (Ti L2,3, Co L2,3, and Co K), and 1s3p resonant inelastic X-ray scattering spectroscopies. Co2+ ions tetrahedrally coordinated by oxygen ions in nanoparticles were found to be located on the surface of agglomerates. Titanium ions were found to be in a tetravalent state (Ti4+). All the samples before the thermal treatment contain an amorphous phase of titanium dioxide on the surface. After annealing in vacuum or hydrogen anatase structure of Ti0.97Co0.03O2 remains and the amorphous phase disappears. Annealing the samples in vacuum or hydrogen leads to clustering metal cobalt at the particles from the bulk of agglomerates.

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Permalink: https://www.hzdr.de/publications/Publ-25588


Experimental determination of gold speciation in sulfide-rich hydrothermal fluids from reduced to oxidized

Trigub, A. L.; Tagirov, B. R.; Kvashnina, K. O.; Lafuerza, S.; Filmonova, O. N.; Nickolsky, M. S.

Abstract

The oxidation state of hydrothermal fluids, which form economic deposits of noble metals, varies in wide limits – from oxidized ones typical for porphyry mineralization to reduced which formed volcanogenic massive sulfide deposits. Sulfur-bearing species, along with chloride, are the most important ligands that form stable aqueous complexes with Au and determine Au concentration in natural ore-generating fluids. Depending on the f(O2) value, in high-temperature fluids (t > 300 °C) the dominant forms of sulfur are sulfides (H2S, HS-), sulfites (SO2, HSO3-, SO32-), sulfates (HSO4-, SO42-), and the radical species (S3-). Here we report an investigation of Au complexation in high-temperature sulfide-bearing fluids of contrasting oxidation states. The solubility of Au was measured in “oxidized” sulfide fluid (H2S/SO42- buffer controls the Red/Ox state) at 450 °C, 1000 bar, and compared with the Au solubility in “reduced” sulfide systems (H2S/HS- predominate) reported in the literature. The measured values of the Au solubility matches best the model of the formation of Au(HS)2- at near-neutral to weakly acidic pH, and AuHS° in acidic solutions. The solubility constants have been determined for the reactions,
Au(cr) + H2S°(aq) + HS- = Au(HS)2- + 0.5 H2(g) log KAu(HS)2- = -0.9 ± 0.1 ,
Au(cr) + H2S°(aq) = AuHS°(aq) + 0.5 H2(g) log KAuHS = -6.5 ± 0.1 .
The average value of log KAu(HS)2- = -1.3 ± 0.5 was calculated for 450 °C (P = 500 – 1500 bar) using all the available Au solubility constants obtained in both “reduced” and “oxidized” sulfide systems. The local atomic environment of Au in high-temperature hydrothermal fluids has been studied using X-ray absorption fine structure spectroscopy (XAFS) in high energy resolution fluorescence detection (HERFD) mode in combination with ab initio molecular dynamics (AIMD) and Reverse Monte Carlo (RMC) simulations. Interpretation of Au L3-edge EXAFS spectra showed that, independently of the Red/Ox (sulfide or sulfide/sulfate systems) and PT – conditions (350 – 450 °C, 500 bar) two S atoms are located in the first coordination shell of Au at 2.29±0.02Å. Comparison of the experimental spectra with those simulated by means of AIMD revealed that EXAFS spectroscopy is not sensitive to the presence of light atoms like S in a distant coordination shell of Au. However, theoretical calculations indicated that the shape of Au L3-edge HERFD-XANES spectra depends upon the composition of the distant coordination shell and, therefore, can be used to discriminate between Au(HS)2-, Au-(HS)-S3- and, probably, other complexes with distant-coordination-shell anions. Experimental Au L3-edge HERFD-XANES spectra are identical for all studied PT- and Red/Ox-parameters. These results allowed us to conclude that Au(HS)2- complex predominates Au speciation in weakly acidic to weakly alkaline pH independently from the oxidation state of the fluid. Besides that, XAFS experiment demonstrated that the formation of mixed Au-HS-Cl complex can be neglected. With increasing pressure (to nkbar) or decreasing temperature (to < 300 °C), due to increasing of concentration of S species in intermediate oxidation states, formation of the Au-HS complexes can be accompanied by the formation of other species with (hydro)sulfite, thiosulfate, (hydro)polysulfide, and sulfur radicals, which would enhance the hydrothermal Au mobility. Stability of these complexes needs further experimental and theoretical examination.

Keywords: gold; solubility; hydrothermal fluids; hydrosulfide complexes; stability constants; X-ray absorption spectroscopy; HERFD-XAS; ab initio molecular dynamics

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Permalink: https://www.hzdr.de/publications/Publ-25587


Indium-bearing sulphides from the Hämmerlein skarn deposit, Erzgebirge, Germany - Evidence for late stage diffusion of indium into sphalerite

Bauer, M. E.; Seifert, T.; Burisch, M.; Krause, J.; Richter, N.; Gutzmer, J.

Abstract

At the Hämmerlein skarn deposit, located in the Western Erzgebirge (Germany), a major cassiterite-dominated Sn mineralization stage is spatially associated with a younger Zn-Cu-In sulphide mineralization stage. In this contribution, we provide the first detailed description of the Zn-Cu-In sulphide mineralization stage, based on field geological observations combined with detailed petrographic studies and electron probe micro analysis data. Indium-rich sulphide mineralization occurs as irregular, semi-massive lenses or as infill of short, discontinuous veinlets that crosscut the cassiterite-bearing skarn assemblage. Indium-and Cu-rich sphalerite and roquesite are found to be closely associated with In-bearing chalcopyrite. The highest In concentrations occur at rims and along cracks of sphalerite grains. The distribution resembles diffusion profiles, suggesting that In enrichment is due to an hydrothermal overprint that postdates the initial formation of both sphalerite and chalcopyrite. Textural relations illustrate that the diffusion fronts in sphalerite grains are thicker where they are in contact to anhedral masses of hematite and magnetite. Our observations suggest that indium enrichment in sphalerite at the Hämmerlein skarn deposit is due to the decomposition of In-bearing chalcopyrite. The resultant release of Fe led to the formation of hematite and magnetite, whereas Cu and In were incorporated into sphalerite along grain boundaries and micro-fractures. Incorporation into the sphalerite lattice took place by coupled substitution of Cu+ + In3+ ↔ 2 Zn2+, suggesting that the concurrent availability of Cu and In may be an essential factor to enrich In in sphalerite in hydrothermal ore-forming environments.

Keywords: Indium; sphalerite group minerals; chalcopyrite; roquesite; diffusion; skarn

Permalink: https://www.hzdr.de/publications/Publ-25586


Efficient Correlation-Free Many-States Lattice Monte Carlo on GPUs

Kelling, J.; Ódor, G.; Weigel, M.; Gemming, S.

Abstract

We'll present a method for highly efficient lattice Monte Carlo simulations with correlation-free updates. Achieving freedom from erroneous correlations requires random selection of lattice sites for updates, which must be restricted by suitable domain decomposition to create parallelism. While approaches based on caching limit the number of allowed states, the multisurface-type approach presented here allows arbitrarily complex states. The effectiveness of the method is illustrated in the fact that it allowed us to solve a long-standing dispute around surface growth under random kinetic deposition in the KPZ-universality class. The method has also been applied to Potts models and is suitable for spin-glass simulations, such as those required to test quantum annealers, like D-Wave.

Keywords: Lattice Monte Carlo; GPU; Surface Growth; Kardar-Parisi-Zhang

Permalink: https://www.hzdr.de/publications/Publ-25585


Classification at 10Hz: Protecting High-Power Lasers with Deep Learning

Kelling, J.; Gebhardt, R.; Helbig, U.; Bock, S.; Schramm, U.; Juckeland, G.

Abstract

In this talk we present our approach to automatic detection of critical failure states in pulsed Petawatt laser systems, used for investigations of exotic states of matter and medical applications. The beam shape is controlled to avoid high destructive energy densities. However, randomly occurring states threatening the device must be detected between pulses and trigger an interlock in the device firing at 10Hz.

Our automation approach, presented here, uses deep learning via the Caffe framework. The states we are aiming to detect are rare; thus, training data for this category is scarce. We address this by identifying regions of interest based on physical properties of the system.

Keywords: image classification; deep learning; smart laser operation; OpenCV

  • Lecture (Conference)
    Minds Mastering Machines [M³], 09.-11.10.2017, London, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-25584


Strahlenbiologische Experimente im Experimentalraum der Universitäts Protonentherapie Dresden

Beyreuther, E.

Abstract

No Abstract available

  • Invited lecture (Conferences)
    Seminar Nuklearmedizin, Medizinische Fakultät Carl Gustav Carus, TU Dresden, 30.05.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25582


Radiation dose rate: a factor of importance in laser-radiooncology?

Beyreuther, E.

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  • Invited lecture (Conferences)
    Preparation of scientific collaborations on medical applications with laser plasma accelerators, 09.05.2017, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25581


Experimental animal models for radiobiological studies with low penetrating beams

Beyreuther, E.; Brüchner, K.; Hideghety, K.; Karsch, L.; Krause, M.; Leßmann, E.; Schmidt, M.; Schürer, M.; Szabo, R.; Pawelke, J.

Abstract

The development of new radiotherapeutic approaches is a long-time process where the general concept should be proven from time to time even though clinical requirements, i.e. on particle energy, are not yet fulfilled. Examples are laser accelerated particle beams, which are promised to replace classical ion radiotherapy, and proton and X-ray micro beams. For these low penetrating beams in vivo models are required that allow for full penetration, e.g. by ~25 MeV proton beams with a penetration depth of ~4 mm, currently available at laser driven accelerators. As the standard tumour model on mice leg cannot be applied for this purpose a new small animal tumour model on mice ear was established for the investigation of tumour response, whereas for the study of normal tissue toxicity Zebrafish embryos were applied.

For the mouse ear tumour model, human tumour cells of three different entities (HNSCC FaDu, LN229 glioblastoma, A549 adenocarcinoma) were injected subcutaneously in the right ear of NMRI nude mice and growing tumours were characterized with respect to growth parameters, histology and 200 kV X-ray dose dependent tumour growth delay. Histological analyses reveal bordered tumours at treatment size (~10 mm³) that interact with the surrounding tissue and activate endothelial cells to form vessels. By X-ray treatment optimised dose ranges for inducing tumour growth delay but not tumour control were determined and a full scale radiobiological experiment at a clinical and a laser-accelerator was performed with FaDu tumours.

In order to quantify the normal tissue toxicity after irradiation with low energy beams wildtype Zebrafish embryos were applied whose size of ~1 mm allow for the full penetration, e.g. by ~10 MeV proton beams. Measurements of the radiobiological response to high (150 MeV) and low energy protons from a conventional therapy facility provide comparative data on survival and immune response for further studies with laser driven beams.

The results obtained during the establishment of the mouse ear tumour model and the Zebrafish embryo normal tissue model will be presented together with first findings of experiments with conventional and laser driven particle beams.

Acknowledgement: The work was supported by German BMBF, grant nos. 03ZIK445 and 03Z1N511 and ELI-ALPS project (GINOP-2.3.6-15-2015-00001).

  • Contribution to proceedings
    63rd Annual Radiation Research Society Meeting, 15.-18.10.2017, Cancun, Mexico
    Proceedings of the 63rd Annual Radiation Research Society Meeting

Permalink: https://www.hzdr.de/publications/Publ-25580


Interaction between magnetic moments and itinerant carriers in d0 ferromagnetic SiC

Liu, Y.; Yuan, Y.; Liu, F.; Böttger, R.; Anwand, W.; Wang, Y.; Semisalova, A.; Ponomaryov, A.; Lu, X.; N’Diaye, A. T.; Arenholz, E.; Heera, V.; Skorupa, W.; Helm, M.; Zhou, S.

Abstract

Elucidating the interaction between magnetic moments and itinerant carriers is an important step to spintronic applications. Here, we investigate magnetic and transport properties in d0 ferromagnetic SiC single crystals prepared by postimplantation pulsed laser annealing. Magnetic moments are contributed by the p states of carbon atoms, but their magnetic circular dichroism is different from that in semi-insulating SiC samples. The anomalous Hall effect and negative magnetoresistance indicate the influence of d0 spin order on free carriers. The ferromagnetism is relatively weak in N-implanted SiC compared with that in Al-implanted SiC after annealing. The results suggest that d0 magnetic moments and itinerant carriers can interact with each other, which will facilitate the development of SiC spintronic devices with d0 ferromagnetism.

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Permalink: https://www.hzdr.de/publications/Publ-25579


Current-driven flow in a liquid-metal-battery-like geometry

Starace, M.; Weber, N.; Weier, T.; Ashour, R.; Kelley, D.; Salas, A.

Abstract

Introduction
Fluid flow can be both a boon and a curse for liquid metal batteries. One one hand, it may promote mixing of the anode metal into the cathode, preventing it from lingering on the electrolyte-cathode interface. On the other hand, it could momentarily displace part of the electrolyte layer and thus cause a short circuit. The experiment presented here consists of a cylindrical container filled with GaInSn bounded by copper current collectors on the top and bottom, which are attached a power supply unit. The current collector is electrically insulated except for a circular surface whose area is 100 times smaller than that of the bottom current collector. This geometry emulates that of a battery whose cathode consists of a liquid metal drop attached to the top current collector dipped into the electrolyte layer while the anode extends throughout the bottom part of the container. An ultrasound Doppler array was used to perform velocimetry measurements of the electro-vortex flow perpendicularly to the cylindrical axis. In addition, the fluid flow of this setup was also simulated numerically.

Results
While currents ranging from 10 A to 100 A are supplied to the system, the flow pattern appears to consists of multiple stationary swirls, which is in general agreement with numerical results. Additional UDV measurements that are parallel to the cylindrical axis will be performed to obtain a better understanding of the flow structure.

Fig. 1: Velocity profile of the electro-vortex experiment while 100 A are flowing through it. The ultrasound transducers in the array are arranged along the height of the cylinder on the left hand side and measure the radial component of the velocity within one plane.

Keywords: liquid metal battery; electro-vortex flow; ultrasound Doppler velocimetry

  • Lecture (Conference)
    International workshop on liquid metal battery fluid dynamics (LMBFD 2017), 16.-17.05.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25578


Liquid metal batteries: activities at the Helmholtz-Zentrum Dresden - Rossendorf

Weier, T.; Galindo, V.; Horstmann, G. M.; Landgraf, S.; Nimtz, M.; Salas, A.; Starace, M.; Stefani, F.; Weber, N.

Abstract

The talk will provide an overview of the liquid metal battery (LMB) related activities at Helmholtz-Zentrum Dresden - Rossendorf (HZDR) with a focus on magnetohydrodynamic aspects of future large scale LMBs. High current densities in the range of 4 up to 130 kA/m-2, as typical for LMBs, together with cells of large cross section will result in substantial currents accompanied by considerable magnetic fields. Thus electromagnetically driven flows and instabilities should be of concern for large enough installations, especially when the thin electrolyte layers necessitated by the limited open circuit voltages are taken into account. Beneficial effects of mild electromagnetically driven flows are to be expected for the cathodes were mixing should improve cell performance.

The Tayler instability (TI) can be understood as a generic case of a current driven instability under perfectly uniform current, i.e., ideal conditions. In this sense it constitutes sort of an upper bound for a current bearing fluid to remain at rest. Modifying the magnetic field distribution in the cell is an effective means to suppress the TI. Different field configurations to achieve TI suppression and their relative merits will be discussed and related to TI saturation mechanisms. Non-uniform current distributions are more typical for real settings. They give rise to rotational Lorentz force distributions and will thereby also generate electro-vortex flows (EVFs). In terms of LMBs the concrete shape of the current collectors plays a crucial role in whether EVFs exist and how they might interact with the TI. We will conclude with a discussion of electromagnetically exited interface instabilities quite similar to the sloshing modes known from aluminium reduction cells.

Keywords: liquid metal batteries; Tayler instability; electro-vortex flows; metal pad roll instability; sloshing

  • Lecture (Conference)
    International Workshop on Liquid Metal Battery Fluid Dynamics (LMBFD2017), 16.-17.05.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25577


Writing magnonic waveguides in Fe U+2076 U+2080 Al U+2084 U+2080 with a nano-sized ion beam

Osten, J.; Hula, T.; Wagner, K.; Xu, X.; Hlawacek, G.; Bali, R.; Potzger, K.; Lindner, J.; Fassbender, J.; Schultheiss, H.

Abstract

The wave like excitation quanta of ferromagnets, called magnons, waves, the are promising candidates for spin transport in lateral devices. Fe60Al40films in the B2 phase are paramagnetic. Starting from a Fe60Al40film in the paramagnetic phase we use ion irradiation to randomize the site occupancies and, thereby, transform it into the chemically disordered, ferromagnetic A2 phase. To detect spin waves we employed micro-focus Brillouin light scattering spectroscopy (μBLS). Using a highly focused Ne+-ion beam He/Ne-Ion Microscope we create spatially well defined ferromagnetic A2-Fe60Al 40 spin-wave conduits of widths 2 and length 10 μm. One of the ferromagnetic conduit is surrounded by the paramagnetic B2- Fe60Al40. In addition, a freestanding 2 μm wide stripe has been prepared for comparison.
For the excitation of spin waves we processed a microwave antenna on top of these stripes. To investigate the spinwave propagation in the so called Damon-Eshbach geometry, an external magnetic field is applied perpendicular to the long edge of the ferromagnetic stripe. Measurements shows that spin wave spectra are influenced by the surrounding paramagnetic material due to a different internal field distribution.
Furthermore, we have also studied the fundamental transversal mode. Our findings where that the mode width for the embedded stripe was alway larger compared to the freestanding stripe. Surrounding a ferromagnetic conduit with a paramagnetic material, in materials exhibiting disorder-induced ferromagnetism, can be a way to tune spin-wave propagation.

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  • Poster
    IEEE international magnetics conference Intermag Europe 2017, 24.-28.04.2017, Dublin, Irland

Permalink: https://www.hzdr.de/publications/Publ-25576


Metal pad roll in cylinders: perturbation theory vs. DNS

Herreman, W.; Nore, C.; Guermond, J.-L.; Cappanera, L.; Weber, N.

Abstract

Liquid metal batteries (LMBs) structurally have much in common with electrolysis cells that are used in the Al-industry and therefore it can be expected that they are prone to similar magneto-hydrodynamical instabilities. Metal pad rolling is one of many instabilities that is currently in the spotlight.

The physical origin of this metal pad roll instability in reduction cells is well described in a furnished literature that goes back to the 70’s. Most theoretical insights have however been found within the restrictive context of quite a number of supplementary assumptions (shallow layers, inviscid, magneto-static, negligible terms in Lorentz force). In lab-scale devices, fluid layers are however not necessarily shallow and the set-up is also small enough for viscous dissipation to become important. Finally, also the magnetic dissipation cannot be ignored given that stronger magnetic fields are necessary to trigger the instability. A critical
comparison between theory and experiments or direct numerical simulation (DNS) dedicated to lab-scale devices requires a more detailed stability model.

In this talk, I present a theoretical stability analysis dedicated to cylindrical reduction cells (2 layers). Using a perturbative approach we find explicit formula for the growth rate of the metal pad roll instability and without making the most common assumptions. We deal with fluid layers of arbitrary heights and incorporate both magnetic and viscous damping effects. We confront our theory to direct numerical simulations (DNS) that are done with two different multiphase MHD solvers (SFEMaNS and OpenFOAM). This comparison also allows us to measure what precision really is required to obtain converged three-dimensional numerical simulations.

  • Lecture (Conference)
    International workshop on liquid metal battery fluid dynamics, 16.-17.05.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25575


Writing magnonic waveguides in FeAl with an nano-sized ion beam

Osten, J.; Hula, T.; Wagner, K.; Xu, X.; Hlawacek, G.; Bali, R.; Potzger, K.; Lindner, J.; Fassbender, J.; Schultheiss, H.

Abstract

Spin waves, the eigen-excitations of ferromagnets, are promising candidates for spin transport in lateral devices. Fe60Al40 films in the B2 phase are paramagnetic. Starting from a FeAl film in the paramagnetic phase the incident ions randomize the site occupancies and, thereby, transform it into the chemically disordered, ferromagnetic A2 phase.
The aim is to investigate spin wave propagation in this ferromagnetic material in free standing structures as well as in ferromagnetic structures embedded within a paramagnetic matrix. Using Helium-Ion microscopy we create spatially well defined ferromagnetic FeAl conduits for spin waves with resolution down to nm range. Two different ferromagnetic stripes were implanted in a microstructured paramagnetic FeAl. A freestanding 2 𝜇m width stripe. And a stripe of the same width which was embedded in a wider paramagnetic FeAl stripe. For the excitation of spin waves we processed a microwave antenna on top of these stripes. To detect spin waves we employed Brillouin light scattering microscopy. We show that the spin wave spectra are influenced by the surrounding paramagnetic material due to a different internal field distribution. The authors acknowledge financial support from the Deutsche Forschungsgemeinschaft within programme SCHU 2922/1-1.

Involved research facilities

Related publications

  • Lecture (Conference)
    DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM), 19.-24.03.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25574


18F-Labeled indole-based analogs as highly selective radioligands for imaging sigma-2 receptors in the brain

Wang, L.; Ye, J.; He, Y.; Deuther-Conrad, W.; Zhang, J.; Zhang, X.; Cui, M.; Steinbach, J.; Huang, Y.; Brust, P.; Jia, H.

Abstract

We have designed and synthesized a series of indole-based σ2 receptor ligands containing 5,6-dimethoxyisoindoline or 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline as pharmacophore. In vitro competition binding assays showed that all ten ligands possessed low nanomolar σ2 receptor affinity (Ki = 1.79–5.23 nM) and high subtype selectivity (Ki (σ2)/Ki (σ1) = 56–708). Moreover, they showed high selectivity for σ2 receptor over the vesicular acetylcholine transporter (>1000-fold). The corresponding radiotracers [18F]16 and [18F]21 were prepared by an efficient one-pot, two-step reaction sequence with a home-made automated synthesis module, with 10–15% radiochemical yield and radiochemical purity of >99%. Both radiotracers showed high brain uptake and σ2 receptor binding specificity in mice.

Keywords: sigma-2 receptors; 18F; indole-based analogs; brain

Permalink: https://www.hzdr.de/publications/Publ-25573


Ansys-cfx simulations – multiple size group (musig) model for bubble coalescence and break-up in multiphase flows

Liao, Y.

Abstract

The main focus of the CFD department at HZDR is the qualification of CFD-codes for multiphase flows. This includes particularly model development as well as validation and testing based on high quality experimental data obtained at the TOPFLOW experimental test facility operated especially for this purpose in the research center. The models developed at HZDR are implemented into the commercial CFD-code CFX produced by the ANSYS Inc. Corporation.
The talk discusses the development of the MUSIG (Multiple-Size-Group) model for poly-disperse turbulent gas–liquid mixtures and its extension to phase change. It includes the development of a generalized model for bubble coalescence and breakup in turbulent bubbly flow, which takes into account all important mechnisms. The generalization makes it possible to use a unified set of models for different flow configurations and avoid arbitrary adjustment. The validation results for adiabatic air-water and evaporating/condesning steam-water flows are presented. In addition, the implementation of appropriate heterogeneous nucleation models for boiling flow is discussed.

Keywords: MUSIG; Poly-disperse bubbly flow; Coalescence and breakup; Nucleation; Phase change

Involved research facilities

  • TOPFLOW Facility
  • Lecture (Conference)
    XXXVII Dynamics Days, Dynamics Days Europe International Conference, 05.-09.06.2017, Szeged, Hungary

Permalink: https://www.hzdr.de/publications/Publ-25572


Targets for high repetition rate laser facilities: needs, challenges and perspectives

Prencipe, I.; Fuchs, J.; Pascarelli, S.; Schumacher, D. W.; Stephens, R. B.; Alexander, N. B.; Briggs, R.; Büscher, M.; Cernaianu, M. O.; Choukourov, A.; de Marco, M.; Erbe, A.; Fassbender, J.; Fiquet, G.; Fitzsimmons, P.; Gheorghiu, C.; Hund, J.; Huang, L. G.; Harmand, M.; Hartley, N.; Irman, A.; Kluge, T.; Konopkova, Z.; Kraft, S.; Kraus, D.; Leca, V.; Margarone, D.; Metzkes, J.; Nagai, K.; Nazarov, W.; Lutoslawski, P.; Papp, D.; Passoni, M.; Pelka, A.; Perin, J. P.; Schulz, J.; Smid, M.; Spindloe, C.; Steinke, S.; Torchio, R.; Vass, C.; Wiste, T.; Zaffino, R.; Zeil, K.; Tschentscher, T.; Schramm, U.; Cowan, T. E.

Abstract

A number of laser facilities coming on–line all over the world promise the capability of high–power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating and laser–driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities.

Keywords: Target design and fabrication < High power laser related laser components; High energy density physics

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Permalink: https://www.hzdr.de/publications/Publ-25571


Do we need improved (dual-energy) CT imaging?

Troost, E.

Abstract

In the era of image-guided high-precision radiotherapy, all clinically used imaging modalities need to benefit the individual patient’s treatment outcome in order to be reimbursed. From a radiation oncologist’s point of view dual-energy CT (DECT) ought to (1) improve target volume delineation, (2) decrease proton range uncertainty and (3) guide patient stratification using advanced image analysis methods, i.e., Radiomics.

(1) With the acquisition of DECT scans more information on the tissue composition and its contrast can be gathered. This may potentially air delineation of the primary tumor and surrounding organs at risk. Possibly, even the inter-observer variability may be reduced. In order to assess whether this is a measurable effect, we are currently conducting a delineation study. However, can this potential benefit also be transferred into clinical routine?

(2) Using DECT, the prediction of electron density (for photon therapy) and stopping-power ratio (for proton therapy) can be improved. Consequently, DECT would increase overall accuracy due to a patient-specific calculation without neglecting the intra- and inter-patient tissue diversity and variability. In particle therapy, CT-related range uncertainties may be reduced and the full potential of the beam modality subsequently exploited. Do we, however, dare to directly apply this in our clinics?

(3) Apart from improved treatment planning and delivery, DECT may also further characterize the primary target volume and possibly metastatically affected lymph nodes to predict outcome and enable patient stratification. This approach has been shown beneficial on non-contrast enhanced CT scans in non-small cell lung and head and neck cancer patients. Thus far, there are no data on the value of DECT. Thus, we need to ask: Are our current imaging protocols good enough to be quantitative? Do we need standardized imaging protocols in our own institution and different institutions? What does it take to make clinical decisions based on Radiomics?

Keywords: Dual-energy CT; Radiomics; radiotherapy

  • Invited lecture (Conferences)
    Jahrestagung der BIOMEDIZINISCHEN TECHNIK und Dreilaendertagung der MEDIZINISCHEN PHYSIK, 10.-13.09.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25570


Quantitative mineralogical analysis of European Kupferschiefer ore

Rahfeld, A.; Kleeber, R.; Möckel, R.; Gutzmer, J.

Abstract

Kupferschiefer samples from five distinct deposits in Germany and Poland were studied with the aim to quantitatively determine their mineralogical composition using complementary approaches. Their inherently extremely fine-grained matrix, sheet silicate-dominated mineralogy, and highly variable copper sulphide content in the presence of organic components render quantitative mineralogical analysis difficult. In an attempt to develop a comprehensive yet feasible analytical routine for Kupferschiefer black shale and associated sandstone- and carbonate-hosted ores, analytical techniques were tested and adapted to suit this purpose. This study focuses on a combination of mineralogical approaches using quantitative X-ray diffraction (XRD) and image-based automatic mineral liberation analyses (MLA). Quantitative bulk-powder XRD was achieved by Rietveld refinement, based on phase identification and selection of suitable structural models. The identified minerals were verified with scanning electron microscopic measurements coupled with energy dispersive X-ray spectroscopy (EDX) and optical microscopy. Results of QXRD and MLA were compared to chemical assay data. It is concluded that MLA and QXRD deliver satisfactory results for this complex raw material, but only when used in combination). When used independently, XRD and MLA are susceptible to significant errors related especially to sample preparation, mineral misidentification or quantification. To assure a successful quantitative mineralogical description of complex raw materials or processing products it thus is strongly recommended to verify all mineralogical information by independent analytical techniques – and to validate quantitative mineralogical information with quantitative chemical data.

Keywords: Kupferschiefer; black shale; XRD; MLA; analysis; copper sulphides; Rietveld refinement

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Permalink: https://www.hzdr.de/publications/Publ-25569


Impact of robust treatment planning on single- and multi-field optimized plans for proton beam therapy of unilateral head and neck target volumes

Cubillos-Mesías, M.; Baumann, M.; Troost, E. G. C.; Lohaus, F.; Löck, S.; Richter, C.; Stützer, K.

Abstract

Background: Proton beam therapy is promising for the treatment of head and neck cancer (HNC), but it is sensitive to uncertainties in patient positioning and particle range. Studies have shown that the planning target volume (PTV) concept may not be sufficient to ensure robustness of the target coverage. A few planning studies have considered irradiation of unilateral HNC targets with protons, but they have only taken into account the dose on the nominal plan, without considering anatomy changes occurring during the treatment course.
Methods: Four pencil beam scanning (PBS) proton therapy plans were calculated for 8 HNC patients with unilateral target volumes: single-field (SFO) and multi-field optimized (MFO) plans, either using the PTV concept or clinical target volume (CTV)-based robust optimization. The dose was recalculated on computed tomography (CT) scans acquired during the treatment course. Doses to target volumes and organs at risk (OARs) were compared for the nominal plans, cumulative doses considering anatomical changes, and additional setup and range errors in each fraction. If required, the treatment plan was adapted, and the dose was compared with the non-adapted plan.
Results: All nominal plans fulfilled the clinical specifications for target coverage, but significantly higher doses on the ipsilateral parotid gland were found for both SFO approaches. MFO PTV-based plans had the lowest robustness against range and setup errors. During the treatment course, the influence of the anatomical variation on the dose has shown to be patient specific, mostly independent of the chosen planning approach. Nine plans in four patients required adaptation, which led to a significant improvement of the target coverage and a slight reduction in the OAR dose in comparison to the cumulative dose without adaptation.
Conclusions: The use of robust MFO optimization is recommended for ensuring plan robustness and reduced doses in the ipsilateral parotid gland. Anatomical changes occurring during the treatment course might degrade the target coverage and increase the dose in the OARs, independent of the chosen planning approach. For some patients, a plan adaptation may be required.

Keywords: proton therapy; single-field optimization; multi-field optimization; robust optimization; adaptive radiation therapy; head and neck cancer

Permalink: https://www.hzdr.de/publications/Publ-25568


Phage display – a new tool for the recovery of critical elements from primary and secondary sources

Lederer, F.; Matys, S.; Bachmann, S.; Curits, S.; Macgillivray, R. T. A.

Abstract

The development of effective and ecofriendly processes for the recovery of critical elements poses a challenge for scientists all over the world. Beside the relevance for the environment new products and techniques have to be highly specific for target materials and be economically applicable. Critical elements such as rare earth elements are part of a multitude of modern electronic devices. However, their recycling rate is low partly due to the similar chemical and physical properties of the elements making their separation difficult.
To generate highly specific peptides that bind specifically to individual elements of interest, the phage surface display (PSD) technology was used. PSD technology was originally developed to identify peptides with high binding specificity for biological molecules such as viruses, antibodies or fusion proteins. Later the technology was successfully applied for inorganic targets as well.
In the current project four different fluorescent phosphor components were used to identify a small number of specific binding peptides via PSD. The newly identified peptides differ strongly in their amino acid composition and binding behavior. Binding properties can be improved by substitution of individual amino acids by more effective amino acids. The application of peptides in bioflotation processes is now being tested as an efficient separation process for rare earth minerals.
In summary, phage surface display is a promising tool for the development of highly specific binding peptides. The development of ecofriendly material specific collectors in bioflotation and separation processes has the potential to revolutionize traditional recycling techniques.

Keywords: bioflotation; phage surface display

  • Poster
    22.International Biohydrometallurgy Symposium, 24.-27.09.2017, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25567


Characterisation of porosity in zirconia-based nanopowders

Prochazka, I.; Cizek, J. A.; Melikhova, O.; Hruska, P.; Anwand, W.; Konstantinova, T. E.; Danilenko, I. A.

Abstract

Porosity in several zirconia-based pressure compacted nanopowders was studied using the positron lifetime technique combined with the mass-density measurements. Two kinds of pores were identified: (i) the larger pores of. 10 to 19 nm diameter arising likely from a formation of secondary particle aggregates, and (ii) the smaller ones (. 1 nm) which are obviously of a more complex origin

Keywords: Nanopowders; Porosity; Positron lifetime; Zirconia

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-25566


Early report on quality of life and dosimetric parameters related to adverse effects in prostate cancer patients following normo-fractionated proton therapy.

Agolli, L.; Dutz, A.; Löck, S.; Hölscher, T.; Simon, M.; Makocki, S.; Baumann, M.; Troost, E. G. C.; Krause, M.

Abstract

Objectives: We report the quality of life (QoL) and the impact of dose-volume-parameters on the gastrointestinal (GI) and genitourinary (GU) toxicities in localized/locally advanced prostate cancer patients treated with definitive normo-fractionated (74-76Gy) proton therapy (PT).
Methods: Twenty-five patients treated in the context of an approved clinical study (Proto-R-Prostata) were selected. Three intraprostatic fiducial markers were placed for daily position verification. A water-filled endo-rectal balloon was placed prior to each fraction. Toxicity and QoL were collected prospectively. The first were graded according to CTCAE v4, the latter by EORTC C30 and PR25 QoL questionnaires. The organs at risk (OARs; rectal wall, whole rectum, whole bladder, bladder wall, anterior and posterior bladder wall) were re-contoured. The dose (Gy) to 5-95% of the volume of OARs (D5-D95%) was reported in 5 % increments, as the volume (cc) receiving an absolute dose of 5-75 Gy (V5-V75Gy). Correlations between dose-volume-parameters to the OARs and toxicities were modelled by logistic regression.
Results: Based on the EORTC-C30, physical functioning and social functioning had a slight worsening after PT, but they improved 3 months after PT, whereas the emotional functioning increased slightly during PT and significantly 3 month after PT (p=0.035). Role functioning showed a statistically significant decrease at the end of PT (p=0.017), but also a subsequent improvement. A correlation was found between GU toxicities during PT and the functional and symptom scale based on the EORTC-PR25 (pain, urinary symptoms and hormonal treatment related symptoms, respectively). Dose-volume parameters V5-V20Gy to the anterior bladder wall and V60–V70Gy to the posterior bladder wall were significantly related to cystitis. V5Gy, V15Gy to the posterior bladder wall and V15-V20Gy to the anterior bladder wall had significant impact on urinary incontinence and urinary frequency, respectively.
Conclusions: QoL during/after PT was reported to be good. The estimated dosimetric parameters can be useful to further plan optimization and to find adequate constraints to PT.

  • Poster
    Langendorff Symposium 2017, 14.-15.07.2017, Freiburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25565


Bio-collector based rare earth mineral flotation and recycling

Matys, S.; Lederer, F. L.; Bachmann, S.; Curtis, S.; Macgillivray, R. T. A.

Abstract

Recycling of rare earth components from fluorescent phosphors of fluorescent light bulbs is focussed in the MinePep project. The current recycling rate of rare earths in spent electronic devices is less than 1%, partly due to the similar chemical and physical properties of the elements making their separation difficult. New recycling strategies needs to focus on effective and ecofriendly processes for the recovery of critical elements within such spent electronic devices. Beside the relevance for the environment, new products and techniques need to be highly-specific for target materials and be economically viable.
The identification of highly-specific bio-collector peptides for special fluorescent phosphors was successful by using phage surface display. This technique uses a phage library with a diversity of 109 different peptide expressing phage clones, where each clone expresses a different peptide sequence on one of the phage surface proteins. In affinity binding screens, the target was exposed to the phage library. Phage with a low target affinity were removed while strong binders were amplified and analyzed for their individual binding characteristics. Final goal of this approach is the application of the isolated peptides as bio-collectors in bio-flotation systems.
The fluorescent phosphors LaPO4:Ce,Tb and CeMgAl11O19:Tb were individually exposed to a phage library and highly-specific peptide expressing phage clones were identified and characterized. The amino acid compositions and the target material affinities differ significantly between the identified sequences. Phage specifically bound to the target were visualized by using phage-specific antibodies. A high number of specifically-bound phage was detected. The binding specificities of individual peptides were improved by substitution of individual amino acids within the peptide sequence.
In summary, phage surface display is a promising tool for the development of highly-specific binding peptides. The development of ecofriendly and specific collectors for use in bio-flotation and separation processes has the potential to revolutionize traditional recycling techniques.

Keywords: phage surface display; rare earth minerals; fluorescent lamp powder; flotation

  • Lecture (Conference)
    2nd. Green and Sustainable Chemistry Conference, 14.-17.05.2017, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25563


Calorimetrically determined U(VI) toxicity in Brassica napus correlates with oxidoreductase activity and U(VI) speciation

Sachs, S.; Geipel, G.; Bok, F.; Oertel, J.; Fahmy, K.

Abstract

Radioecological studies depend on the quantitative toxicity assessment of environmental radionuclides. In the low dose regime, the life span of affected organisms is barely shortened enabling the transfer of radionuclides through an almost intact food chain. Lethality-based toxicity estimates are not adequate in this regime because they require higher doses. In the case of radionuclides, increased dosage additionally alters radionuclide speciation, rendering the extrapolation to the low dose regime chemically inconsistent. Here, we demonstrate that microcalorimetry provides a sensitive real-time monitor of low dose toxicity of uranium (in the U(VI) oxidation state) in a plant cell model of Brassica napus. We introduce the calorimetric descriptor “metabolic capacity” and show that it correlates with enzymatically determined cell viability. It is independent of physiological models and robust against the naturally occurring fluctuations in the metabolic response to U(VI) of plant cell cultures. In combination with time-resolved laser-induced fluorescence spectroscopy and thermodynamic modeling, we show that the plant cell metabolism is affected predominantly by hydroxo-species of U(VI) with an IC50 threshold of 90 µM. The data emphasize the little exploited potential of microcalorimetry for the speciation-sensitive ecotoxicology of radionuclides.

Keywords: Uranium; plant cells; metabolism; isothermal microcalorimetry; speciation; TRLFS; thermodynamic modeling

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Permalink: https://www.hzdr.de/publications/Publ-25562


Structure optimisation by thermal cycling for the hydrophobic-polar lattice model of protein folding

Günther, F.; Möbius, A.; Schreiber, M.

Abstract

The function of a protein depends strongly on its spatial structure.
Therefore the transition from an unfolded stage to the functional fold is one of the most important problems in computational molecular biology. Since the corresponding free energy landscapes exhibit huge numbers of local minima, the search for the lowest-energy configurations is very demanding. Because of that, efficient heuristic algorithms are of high value. In the present work, we investigate whether and how the thermal cycling (TC) approach can be applied to the hydrophobic-polar (HP) lattice model of protein folding. Evaluating the efficiency of TC for a set of two-and three-dimensional examples, we compare the performance of this strategy with that of multi-start local search (MSLS) procedures and that of simulated annealing (SA). For this aim, we incorporated several simple but rather efficient modifications into the standard procedures: in particular, a strong improvement was achieved by also allowing energy conserving state modifications. Furthermore, the consideration of ensembles instead of single samples was found to greatly improve the efficiency of TC. In the framework of different benchmarks, for all considered HP sequences, we found TC to be far superior to SA, and to be faster than Wang-Landau sampling.

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Permalink: https://www.hzdr.de/publications/Publ-25561


RNA-profiling of micromilieu parameters in different experimental hHNSCC models

Koi, L.; Wolf, A.; Linge, A.; Löck, S.; Baumann, M.; Krause, M.

Abstract

Introduction: Previous in vivo studies demonstrated that hypoxia measured by pimonidazole staining is associated with local tumor control in human head and neck squamous cell carcinoma (hHNSCC). This project intends to identify and validate genes which are expressed differently in hypoxic and oxic cells and therefore may play an important role in radiation resistance. This might lead to the establishment of new targets and biomarkers for potential therapeutic. Materials and methods: Seven different hHNSCC in nude mice were studied. For gene expression analysis untreated tumors were excised and stained for pimonidazole hypoxic areas. Using laser-capture microdissection (LCM), material was collected separately from consecutive unstained slides. RNA was isolated and subjected to gene expression analysis using nanoString technologies. The applied gene panel included hypoxia classifier (Toustrup et al.) as well as genes that have been reported to be involved in radioresistance, such as genes which are encoding for putative cancer stem cell markers. Results: Several genes showed large differences in expression between hypoxic and well perfused areas. Differences were found in the expression level of hypoxia-associated genes within the hypoxic areas between the individual tumor models. In addition, the more radioresistant tumors do not necessarily coincide with the intensity of the expression of these genes. Besides the hypoxic gene signature, genes encoding for stem cell markers, are significantly different between these two micromilieu areas. Conclusion: LCM allows analysing RNA from different microenvironmental areas. We found significantly different expressions of genes which can play an important role with regard to radioresistance in tumors, and are involved in processes, such as DNA repair, proliferation and invasiveness. In this way, new targets and biomarkers could be established in order to obtain potential therapeutic approaches in combination with radiotherapy.

  • Lecture (Conference)
    15th Acta Oncologica Symposium Biology-Guided Adaptive Radiotherapy, 14.-16.06.2017, Aarhus, Dänemark

Permalink: https://www.hzdr.de/publications/Publ-25560


Fate of Plutonium Released from Nuclear Weapons Tests in Australia

Ikeda-Ohno, A.

Abstract

In the 1950s and 1960s, a series of the British nuclear weapons tests were conducted at different sites in Australia, resulting in the significant dispersion of long-lived and highly radioactive nuclear debris. A reliable assessment of the environmental impact of these radioactive contaminants and their potential implication for human health requires an understanding of their physical/chemical characteristics. This study focuses particularly on the physical/chemical characterisation of the Pu contaminant, the most problematic radioactive contaminant remaining at the former testing sites, by synchrotron-based X-ray microscopy / spectroscopy. The chemical transformation of the Pu contaminant in the relevant environment over the last 50 years and the potential implication for radioecology will be discussed.

Keywords: Actinides; plutonium; nuclear weapons tests; radioactive contaminants; chemical analysis; synchrotron; radio ecology

  • Invited lecture (Conferences)
    Advanced Science Research Center Seminar, 18.07.2017, Tokai, Ibaraki, Japan

Permalink: https://www.hzdr.de/publications/Publ-25559


Evolution of antiferromagnetic domains in the all-in-all-out ordered pyrochlore Nd2Zr2O7

Opherden, L.; Hornung, J.; Herrmannsdörfer, T.; Xu, J.; Islam, A. T. M. N.; Lake, B.; Wosnitza, J.

Abstract

We report the observation of magnetic domains in the exotic, antiferromagnetically ordered all-in-all-out state of Nd2Zr2O7, induced by spin canting. The all-in-all-out state can be realized by Ising-like spins on a pyrochlore lattice and is established in Nd2Zr2O7 below 0.31 K for external magnetic fields up to 0.14 T. Two different spin arrangements can fulfill this configuration which leads to the possibility of magnetic domains. The all-in-all-out domain structure can be controlled by an external magnetic field applied parallel to the [111] direction. This is a result of different spin canting mechanisms for the two all-in-all-out configurations for such a direction of the magnetic field. The change of the domain structure is observed through a hysteresis in the magnetic susceptibility. No hysteresis occurs, however, in the case the external magnetic field is applied along [100].

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  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-25558


Materialwissenschaftliche Untersuchungen für den Orgelbau: Von Bleigieß-Rezepten des 17.Jh zu antikorrosiver Nanotechnologie

Skorupa, W.; Pelic, B.; Werner, H.; Eule, D.

Abstract

Der Vortrag beschäftigt sich mit materialwissenschaftlichen Arbeiten, die in den letzten 10 Jahren stattfanden, um Probleme zu lösen, die sich aus verschiedenen Aspekten der Verwendung metallischer Werkstoffe im Orgelbau ergaben:

1. Die Zusammenarbeit begann mit der Erkundung alter Gießtechniken, wie sie im Zusammenhang mit einem Restaurierungsprojekt der Fa. Eule in Borgentreich/Ostwestfalen notwendig wurden, um Orgelpfeifen aus der Erbauungszeit der Orgel im 17.Jh und davor zu reparieren bzw. in vergleichbarer Weise nachzubauen. Dabei kam es darauf an, die Temperaturableitung am Gießtisch zu erhöhen, um dem Orgelmetall (Blei mit ca. 2% Zinn) eine feinkristalline Struktur und damit eine höhere Steifheit zu verleihen.
2. Eine weitere Arbeit bezog sich auf die Untersuchung von Korrosionsflecken auf den Prospektpfeifen von Silbermann-Orgeln im sächsischen Raum. Der Prospekt einer Orgel ist der Teil, der direkt dem Betrachter zugewandt ist, also die Pfeifen, die man vom Kirchenraum aus direkt sieht. Man sollte wissen, dass der größte Teil des Pfeifenmaterials hinter dem Prospekt verborgen ist. Dabei wurde eine weltweit relative selten verfügbare Technik eingesetzt, bei der ein hochenergetischer Ionenstrahl (Protonen mit 4 MeV) aus dem Vakuum herausgeführt und an der Oberfläche der Orgelpfeifen die Untersuchung mittel Rutherford-Rückstreuspektrometrie sowie protonen-induzierter Röntgen-und Gammastrahlungs-Spektroskopie ermöglicht.
3. Stark bleihaltiges Orgelmetall und Messing sind innerhalb von historischen, aber auch neuerbauten Orgeln korrosiver Belastung durch Essig-und Ameisensäure-Ausdünstungen aus den in den Orgeln notwendig vorhandenen Holzkonstruktionen ausgesetzt. Es wurde auf der Basis der Ionenimplantation und der Dünnschicht-Abscheidung eine Behandlungsmethode entwickelt, mit denen an der Metalloberfläche antikorrosive Schichten mit Dicken im Bereich kleiner 50 nm erzeugt werden können.

Keywords: Gießtechniken; Korrosion; Plasmaimmersions-Ionenimplantation; Orgelpfeife; Nanotechnologie; Blei-Zinn-Legierungen; Kupfer-Zink-Legierungen (Messing)

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  • Lecture (others)
    Eingeladener Seminarvortrag, 26.04.2017, Steinfurt bei Münster, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25557


Zn-Vacancy Related Defects Identified in ZnO Films Grown by Pulsed Laser Deposition

Ling, F. C.-C.; Wang, Z.; Luo, C.; Anwand, W.; Wagner, A.

Abstract

Undoped and Cu-doped ZnO grown on sapphire using pulsed laser deposition (PLD) were studied by positron annihilation spectroscopy (PAS), photoluminescence (PL), high-resolution transmission electron microscopy (HRTEM) and secondary ion mass spectroscopy (SIMS). In the undoped samples, two kinds of VZn-related defects, namely VZn1 and VZn2 are identified. VZn1 was identified in as-grown samples grown at relatively low substrate (~300°C). After annealing at 900°C, VZn-2, the green luminescence (GL) peaking at 2.47 eV and the near band edge (NBE) emission at
3.23 eV in the low temperature photoluminescence (LT-PL) were simultaneously introduced. Another kind of VZn-related defect is identified in the Cu-doped ZnO sample, and is tentatively assigned to the VZn decorated with the Cu.

Keywords: pulsed laser deposition PLD; positron annihilation spectroscopy PAS; photoluminescence PL; transmission electron microscopy TEM; secondary ion mass spectroscopy SIMS; ZnO

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Permalink: https://www.hzdr.de/publications/Publ-25556


Fe+ Implantation Induced Damage in Oxide Dispersion Strengthened Steels Investigated by Doppler Broadening Spectroscopy

Anwand, W.; Leguey, T.; Scepanovic, M.; Jose Sanchez, F.; García-Cortés, I.; Wagner, A.

Abstract

Open volume defects created by 1 MeV Fe+ implantation up to a damage of 15 displacements per atom into Fe14wt%Cr and into oxide dispersion strengthened (ODS) Fe14wt%Cr were investigated by positron annihilation spectroscopy, especially single Doppler broadening (DBS) and coincidence Doppler broadening spectroscopies (cDBS). The influence of W and Ti alloying elements on the evolution of defects during ion implantation were probed in addition. Whereas no effect of the W and Ti alloying constituents on the line-shape parameters S and W could be detected both before and after ion implantation, fine dispersed Y2O3 particles showed important changes in the structural properties compared to pure FeCr steel, which could be detected by DBS and cDBS. The distribution of the electron momenta in implanted ODS Fe14Cr, obtained with cDBS, shows that oxide particles form obstacles for expanded vacancy mobility and that the vacancies are localized around the oxide particles.

Keywords: defects implantation oxide dispersion strengthened (ODS) positron annihilation spectroscopy

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Permalink: https://www.hzdr.de/publications/Publ-25555


E1 and M1 excitations in 54Fe and low-energy M1 strength in open-shell Fe isotopes

Schwengner, R.

Abstract

Dipole excitations in the N = 28 nuclide 54Fe were studied in photon-scattering experiments using bremsstrahlung at the gELBE facility of Helmholtz-Zentrum Dresden-Rossendorf and using quasi-monoenergetic, polarized gamma beams at the HIgS facility of the Triangle Universities Nuclear Laboratory in Durham. We identified intense E1 as well as M1 transitions to spin-1 states up to about 10.6 MeV. In the second part, we present low-energy M1 strength functions of 60,64,68Fe determined on the basis of large-scale shell-model calculations with the goal to study their development from the bottom to the middle of the neutron shell. We find that the zero-energy spike develops toward the middle of the shell into a bimodal structure composed of a weaker zero-energy spike and a scissorslike resonance around 3 MeV, where the summed strengths of the two structures changes only slightly. The summed strength of the scissors region exceeds the total gammaabsorption strength from the ground state by a factor of about three, which explains the discrepancy between total strengths of the scissors resonance derived from (gamma,gamma') experiments and from experiments using light-ion induced reactions.

Keywords: Bremsstrahlung; polarized gamma beam; shell model; M1 gamma-strength function; scissors mode

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Related publications

  • Invited lecture (Conferences)
    6th Workshop on Nuclear Level Density and Gamma Strength, 08.-12.05.2017, Oslo, Norwegen

Permalink: https://www.hzdr.de/publications/Publ-25554


Simplified Expression and Production of Small Metal Binding Peptides

Braun, R.; Matys, S.; Schoenberger, N.; Lederer, F.; Pollmann, K.

Abstract

Phage display for discovery of metal binding peptides is an innovative way to engineer metalsorptive biological structures with a broad spectrum of applications in geobiotechnology, for example in reusable filter modules in biosorption processes. Using state-of-the-art cloning techniques we developed an easy-to-use cloning and expression system, allowing the fast production of identified peptides.

Keywords: phage display; intein; protein engineering; Gibson Assembly; biomining; bioremediation; biosorption

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Permalink: https://www.hzdr.de/publications/Publ-25553


Development of Cobalt- and Nickel-binding peptides for biosorption

Braun, R.; Lederer, F.; Matys, S.; Schoenberger, N.; Pollmann, K.

Abstract

Usage of Phage Display for identification of peptide binding motifs has long been restricted to medical use. However, in the last years more and more publications focused on the interaction between peptides and inorganic material. Especially in Geobiotechnology the characterization of new metal-binding proteins as well as peptide motifs receives increasing attention, as they may be used in metal recovery, biosorption and bioremediation, as well. Here, we describe the application of artificial peptides for the recovery of metal ions form solutions, e.g. leachates. Limitations arise from complicated identification of metal-binding peptides, from high productions costs of chemical synthesized peptides and difficult heterologous expression of small peptides, as they are relatively fast proteolyzed. Therefore applications of such peptides require efficient and economic production systems.
In the present study we aimed for the development of an efficient expression system, expressing previously via Phage Display and Deep sequencing identified peptides as fusions proteins with integrated purification and cleavage tags. Characterization of the purified peptides was performed using quartz crystal microbalance with dissipation monitoring using special coatings for metal immobilization. Knowledge about peptide motifs and metal affinity is crucial for the intended usage of peptides in biosorption processes, e.g. immobilized on membranes. Furthermore, detailed information about peptide-metal interaction may lead to discovery of novel metal-incorporating and –binding enzymes.

Keywords: phage display; peptide; biosorption; metal-binding protein

  • Poster
    22. International Biohydrometallurgy Symposium, 24.-27.09.2017, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25552


Development of Cobalt- and Nickel-binding peptides for biosorption

Braun, R.

Abstract

Usage of Phage Display for identification of peptide binding motifs has long been restricted to medical use. However, in the last years more and more publications focused on the interaction between peptides and inorganic material. Especially in Geobiotechnology the characterization of new metal-binding proteins as well as peptide motifs receives increasing attention, as they may be used in metal recovery, biosorption and bioremediation, as well. Here, we describe the application of artificial peptides for the recovery of metal ions form solutions, e.g. leachates. Limitations arise from complicated identification of metal-binding peptides, from high productions costs of chemical synthesized peptides and difficult heterologous expression of small peptides, as they are relatively fast proteolyzed. Therefore applications of such peptides require efficient and economic production systems. In the present study we aimed for the development of an efficient expression system, expressing previously via Phage Display and Deep sequencing identified peptides as fusions proteins with integrated purification and cleavage tags. Characterization of the purified peptides was performed using quartz crystal microbalance with dissipation monitoring using special coatings for metal immobilization. Knowledge about peptide motifs and metal affinity is crucial for the intended usage of peptides in biosorption processes, e.g. immobilized on membranes. Furthermore, detailed information about peptide-metal interaction may lead to discovery of novel metal-incorporating and –binding enzymes.

Keywords: phage display; peptide; biosorption

  • Lecture (others)
    Microbiology Meeting HZDR - TU Bergakademie Freiberg, 09.01.2017, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25551


Development of Cobalt- and Nickel binding peptides for biosorption

Braun, R.; Matys, S.; Pollmann, K.

Abstract

Interactions between proteins and metals long been scientifically described but still remain hardly understood. They may be used for industrial purposes. In Geobiotechnology metal binding motifs of proteins and peptides are a promising tool in bioremediation as well as in biosorption processes for the recovery of metals. In this work peptide motifs, which have previously been identified using Phage Display, are characterized for their ability to specifically bind cobalt and nickel ions and for their applicability in industrial biosorption processes. Biosorption may be a future alternative to conventional metal sorption processes, as it is less energy-consuming, environmental-friendly and highly selective.

Keywords: biosorption; peptide; metal recovery; phage display

  • Poster
    HZDR PhD seminar, 17.-19.10.2016, Oberwiesenthal, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-25550


Glacier melt buffers river runoff in the Pamir Mountains

Pohl, E.; Gloaguen, R.; Andermann, C.; Knoche, M.

Abstract

Newly developed approaches based on satellite altimetry and gravity measurements provide promising results on glacier dynamics in the Pamir-Himalaya but cannot resolve short-term natural variability at regional and finer scale. We contribute to the ongoing debate by upscaling a hydrological model that we calibrated for the central Pamir. The model resolves the spatiotemporal variability in runoff over the entire catchment domain with high efficiency. We provide relevant information about individual components of the hydrological cycle and quantify short-term hydrological variability. For validation, we compare the modeled total water storages (TWS) with GRACE (Gravity Recovery and Climate Experiment) data with a very good agreement where GRACE uncertainties are low. The approach exemplifies the potential of GRACE for validating even regional scale hydrological applications in remote and hard to access mountain regions. We use modeled time series of individual hydrological components to characterize the effect of climate variability on the hydrological cycle. We demonstrate that glaciers play a twofold role by providing roughly 35% of the annual runoff of the Panj River basin and by effectively buffering runoff both during very wet and very dry years. The modeled glacier mass balance (GMB) of -0.52 m w.e. / yr (2002–2013) for the entire catchment suggests significant reduction of most Pamiri glaciers by the end of this century. The loss of glaciers and their buffer functionality in wet and dry years could not only result in reduced water availability and increase the regional instability, but also increase flood and drought hazards.

Keywords: Upscaling; hydrological model; Pamir; multisource validation data; glaciers; buffer; extreme meteorological events; sustainable river runoff; climate; hydrological cycle

Permalink: https://www.hzdr.de/publications/Publ-25549


Dual-energy CT for photon therapy – benefits and limitations

Möhler, C.; Wohlfahrt, P.; Richter, C.; Greilich, S.

Abstract

In current treatment planning for both photon and particle therapy, a heuristic Hounsfield look-up table (HLUT) is used for the conversion of CT numbers to electron density or particle stopping-power ratios, respectively. However, this conversion is ambiguous and cannot account for patient-specific tissue variability or non-tissue materials (e.g., implants, contrast agent). This can lead to substantial difference in dose distributions. In contrast, dual-energy computed tomography (DECT) allows for direct patient- and tissue- specific determination of radiological quantities. Therefore, DECT is currently being investigated by many groups as an alternative imaging modality.
While the benefit of DECT is rather pertinent in particle therapy, where an accurate range prediction is crucial, we suggest that it might also improve conventional photon treatment planning, especially in the presence of non-tissue materials such as implants. In this context, DECT-based material characterization can help to identify implants of unkown composition. Moreover, their electron density can automatically be correctly assigned, as the DECT algorithm does not require tissue equivalency. This might provide more accurate dose distributions in cases, where the beam traverses a non-tissue material that would deviate considerably from the HLUT.
Furthermore, the acquisition of a DECT scan of patients with administered contrast agent enables the calculation of an image, where the influence of the contrast agent can effectively be removed. This would render the additional native CT scan obsolete, reducing overall CT dose to the patient. Finally, DECT also allows for a certain tuning of contrast by an overlay of the two images, which might be exploited for diagnostic or delineation purposes.

  • Lecture (Conference)
    Jahrestagung der BIOMEDIZINISCHEN TECHNIK und Dreiländertagung der MEDIZINISCHEN PHYSIK, 10.-13.09.2017, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-25548


Dual-energy CT for particle therapy – benefits and limitations

Wohlfahrt, P.; Möhler, C.; Greilich, S.; Richter, C.

Abstract

Due to the physical advantages of particles in energy deposition compared to photons, a high-conformal tumor coverage can be reached while sparing healthy tissue more effectively. However, particle treatment planning is currently associated with large uncertainties related to a CT-based stopping-power and eventually particle range prediction. To fully exploit the physical benefit of particles, this substantial part of the overall range uncertainty of approximately 3.5% of total range should be reduced.
Dual-energy CT (DECT) imaging is a promising technique to increase the accuracy of CT-based range predictions as already shown by many research groups. The effective benefit of DECT for particle treatment planning of cancer patients is currently proven using a comprehensive validation scheme to quantify the potential reduction of range uncertainties in daily clinical practise. In the framework of a joint project between DKFZ and OncoRay, extensive investigations on different levels (inhomogenous phantoms, biological tissue, clinical patient scans) have been performed. Here, a considerably improved accuracy of DECT compared to the current state-of-the-art, single-energy CT (SECT), could be shown in an anthropomorphic ground-truth phantom and biological tissues. Moreover, relative comparisons of predicted particle ranges in more than 100 proton treatment fields of patients reveal median range deviations of 1.5 – 2.0 % of total range between DECT and SECT. Based on these results, the clinical use of DECT-based range prediction would clearly improve the accuracy and robustness of particle treatment planning and is thus highly recommended to be the new standard imaging modality for treatment planning in particle therapy.

  • Lecture (Conference)
    Jahrestagung der BIOMEDIZINISCHEN TECHNIK und Dreiländertagung der MEDIZINISCHEN PHYSIK, 10.-13.09.2017, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-25547


Comparative analysis of uranium bioassociation with halophilic bacteria and archaea

Bader, M.; Müller, K.; Foerstendorf, H.; Schmidt, M.; Simmons, K.; Swanson, J. S.; Reed, D. T.; Stumpf, T.; Cherkouk, A.

Abstract

Rock salt represents a potential host rock formation for the final disposal of radioactive waste. The interactions between indigenous microorganisms and radionuclides, e.g. uranium, need to be investigated to better predict the influence of microorganisms on the safety assessment of the repository. Hence, the association process of uranium with two microorganisms isolated from rock salt was comparatively studied. Brachybacterium sp. G1, which was isolated from the German salt dome Gorleben, and Halobacterium noricense DSM15987T were selected as examples of a moderately halophilic bacterium and an extremely halophilic archaeon, respectively. The microorganisms exhibited completely different association behaviors with uranium. While a pure biosorption process took place with Brachybacterium sp. G1 cells, a multistage association process occurred with the archaeon. In addition to batch experiments, in situ attenuated total reflection Fourier-transform infrared spectroscopy was applied to characterize the U(VI) interaction process. Biosorption was identified as the dominating process for Brachybacterium sp. G1 with this method. Carboxylic functionalities are the dominant interacting groups for the bacterium, whereas phosphoryl groups are also involved in U(VI) association by the archaeon H. noricense.

Keywords: nuclear waste repository; microorganisms from rock salt; Brachybacterium; Halobacterium; in situ ATR FT-IR spectroscopy

Permalink: https://www.hzdr.de/publications/Publ-25546


Recent Progress using the Staudinger Ligation for Radiolabeling Applications

Mamat, C.; Gott, M.; Steinbach, J.

Abstract

The increasing application of positron emission tomography (PET) and single photon emission computer tomography (SPECT) in radiopharmacy and nuclear medicine has stimulated the development of a multitude of novel and versatile bioorthogonal conjugation techniques. Currently, there is particular interest in radiolabeling biologically active, high molecular weight compounds like peptides, proteins or antibodies, but also for the labeling of small organic compounds. An enormous challenge in radiolabeling these biologically active molecules is that the introduction of radiohalogens like fluorine-18 as well as various radiometals proceeds under harsh conditions, which could destroy the biomolecule.
The Staudinger Ligation is one of the most powerful bioorthogonal conjugation techniques. The reaction proceeds over wide temperature and pH ranges; an amide (peptide) bond is formed as the ligation unit, which minimizes distortion of the structure; no isomers are obtained; and the reaction proceeds without any metal catalyst. Due to this adaptability, this robust ligation type is a perfect candidate with a high potential for various applications in the field of radiopharmacy for the labeling of biomolecules under mild conditions.
This review summarizes recent research concerning the implementation of the Staudinger Ligation for radiolabeling applications.

Keywords: fluorine-18; Staudinger Ligation; click chemistry; bioorthogonal

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  • PET-Center

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Permalink: https://www.hzdr.de/publications/Publ-25545


Development of metal ion binding peptides using phage surface display technology

Schönberger, N.; Matys, S.; Flemming, K.; Lehmann, F.; Lederer, F.; Pollmann, K.

Abstract

Phage surface display technology is a useful tool for the identification of biosorptive peptides. In this work it is used for the identification of cobalt, nickel and gallium binding peptides. We present methods for the enrichment of metal ion binding bacteriophage clones from a commercial phage display library. Metal ion selective peptides are suitable to separate as well as concentrate cobalt and nickel from copper black shale leaching products (EcoMetals project) and gallium from industrial waste waters (EcoGaIn project). In contrast to common capture methods of specific binding phage for solid materials the ionic species have to be immobilized prior to the bio-panning procedure. This was realized by chemical complexation of the metal ions using commercial complexing agents on porous matrices. Moreover, an option to harvest non elutable strong binding phage is proposed.

Keywords: Phage Surface Display; biopanning; immobilized metal ions; nickel; gallium; cobalt; metal binding peptides

  • Contribution to proceedings
    22. International Biohydrometallurgy Symposium, 24.-27.09.2017, Freiberg, Deutschland
    22. International Biohydrometallurgy Symposium 2017

Permalink: https://www.hzdr.de/publications/Publ-25544


SIMS on smallest scale

Klingner, N.; Heller, R.; Hlawacek, G.; Facsko, S.

Abstract

Ongoing miniaturization in semiconductor industry, nanotechnology and life science demands further improvements for high-resolution imaging, fabrication and analysis of the produced nanostructures. Continuously shrinking object dimensions lead to an enhanced demand on spatial resolution and surface sensitivity of modern analysis techniques. Secondary Ion Mass Spectrometry (SIMS), as one of the most powerful technique for surface analysis, performed on nanometer scale may comply with this challenge. The mass of sputtered ions directly serves elemental and molecular information and even allows measuring isotope concentrations.

During last decades, primary ion species used in SIMS have optimized in terms of best ionization probabilities and small molecule fragmentation. Thereby, highest mass-resolution has been one of the biggest design goals in the development of new SIMS spectrometers. In contrast to former developments, our approach aims for ultimate lateral resolution.

Typically the lateral resolution is limited by the probe size of the primary ion beam. Minimal probe sizes can be achieved using Gas Field Ionization Sources (GFIS) in a Helium Ion Microscope (HIM). Due to the high brightness of up to 5•109 A•cm-2•sr-1 and the sharp primary ion energy of 30000 ± 1 eV spot sizes below 1 nm can be achieved. In recent years Helium Ion Microscopy has been developed as a valuable tool for nanofabrication and high-resolution imaging. However, in terms of analytical capabilities it is still lacking behind electron microscopes. Recently, we implemented Time of Flight (TOF) spectrometry to the HIM and thus enabled the measurement of the energy of backscattered particles and simultaneously the mass of sputtered ions [1, 2]. SIMS has also been achieved by adding a sophisticated magnetic sector field analyzer to the HIM [3]. In this way SIMS could be performed with unprecedented spot sizes.

Using a sufficient small ion probe size in the HIM the achievable lateral resolution for bulk samples is mainly determined by the size of the collision cascade and the sputtering process by impinging primary ions and backscattered particles. Different binary collision codes were utilized to simulate the ion-solid interaction for various beam and sample parameters. Here we discuss the origin of sputtered particles with respect to the primary ion impact. We will show simulation results for pristine samples as well as in dependence of increasing ion beam fluence. The size of the collision cascade influences the intermixing behavior and therefore the achievable depth resolution [3]. Low primary ion energies would be favorable but widen the spot size in the microscope.

Another constrain for the limited minimal resolution is the finite amount of available sample material, which is analyzed. Therefore it is crucial to collect as much information on the sample composition as possible prior the destruction or intermixing of the sample layers. Collection efficiency of the ion extraction optics should be close to one. Ultimately, the detection limit for an element is determined by the ratio of charged emitted particles during sputtering. This so-called useful yield (UY) was studied for Helium and Neon and could be enhanced by Oxygen gas flooding on the sample surface [4]. The detection limit was calculated for various minimal feature sizes for a 10nm thick layer (Fig 1). Unfortunately the charge state of sputtered particles is strongly influenced by the surface chemistry, which makes quantification hard and standards necessary.


Fig 1: Detection Limit for SIMS as a function of the minimum feature size and a layer thickness of 10 nm for various usefull yields (UY).

The available space in the HIM is strongly limited by the arrangement of multiple devices around the focal point making it necessary to extract the secondary ions and guide them to the mass spectrometer. We will discuss benefits and drawbacks of several approaches.

As a common feature for all kind of mass spectrometers, the ions have to be extracted in a narrow beam and accelerated to a sharp ion energy. Simultaneously, the applied extraction fields near the sample surface or extensions should not distort the primary beam focus and influence the optical performance of the microscope.

The TOF spectrometer presented here is minimal invasive to the microscope and therefore the high-resolution capabilities of the device are not derogated when the TOF setup is not in use. The system can be retrofitted and flange-mounted on one of the free ports the HIM offers.

The TOF measurements are triggered by blanking the primary ion beam into an existing Faraday cup and release the beam for short time windows to ensure minimal applied fluence. Using a custom made blanking electronic we could achieve pulse lengths down to 17 ns. The sputtered secondary ions are accelerated by applying a bias voltage up to +/-500 V towards the extraction system on ground potential. We used ion optics simulations and a genetic algorithm to tune the ion optics inside the spectrometer for high mass resolution and high extraction efficiency. A trajectory simulation for the secondary ions flight paths within the ion extraction system is shown in Fig. 2.


Fig 2: Simulated trajectories of 1000 ions through the ion extraction optics. For best extraction efficiency the sample (on the left side) must be oriented towards the extraction system. The optics was designed to use a maximum extraction potential of +/-500V to ensure use of standard sample holder.

The secondary ion mass spectrometry technique can be used in the microscope to measure mass spectra of selected regions of interest, to create depth profiles on small spots or to map the lateral distribution of selected element masses. The measurements are recorded in list mode and allow post evaluation. Preliminary TOF-SIMS spectra obtained from different samples are presented in Fig 3.


Fig 3: Secondary ion mass spectra using preliminary extraction system for different samples. (a) Reference sample containing carbon, silicon, nickel and gold (b) aluminum foil (c) organic glue.

TOF-SIMS in the HIM is perfectly capable of delivering an excellent elemental contrast for imaging purposes. However the lateral resolution could not reach the intrinsic imaging capabilities by just measuring the secondary electron yield. In order to combine the elemental information with the high resolution imaging correlative microscopy represents the best way. However, quantification of elements in mixed layers cannot be done from pure SIMS measurements without comparison to standards. This drawback of SIMS is partly compensated by additional measurement of TOF backscattering spectra.

In the present contribution we intent to present the technical realization of our TOF-SIMS approach and show first results, drawbacks and derived conclusions for the practical use of this promising technique. We will further stress out the benefits of correlative measurements in different modes (SIMS, backscattered particles, secondary electrons), giving a maximum of information on the subject of interest.

[1] N. Klingner, R. Heller, G. Hlawacek, J. von Borany, J.A. Notte, J. Huang, S. Facsko. Ultramicroscopy 162 (2016), 91-97
[2] R. Heller, N. Klingner, G. Hlawacek. Helium Ion Microscopy, Chapter 12, Springer (2016)
[3] T. Wirtz, D. Dowsett, P. Philipp. Helium Ion Microscopy, Chapter 13. Springer (2016)
[4] T. Wirtz, N. Vanhove, L. Pillatsch, D. Dowsett, S. Sijbrandij, J.A. Notte. Applied Physics Letters 101 (2012)

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Related publications

  • Invited lecture (Conferences)
    23-rd International Conference of Ion-Surface Interactions 2017, 21.-25.08.2017, Moscow, Russia

Permalink: https://www.hzdr.de/publications/Publ-25543


Influence of Electric Fields on the Electron Transport in Donor–Acceptor Polymers

Förster, A.; Günther, F.; Gemming, S.; Seifert, G.

Abstract

The influence of an electric field on different properties of the donor–acceptor polymer diketo-pyrrolo-pyrrole bithiophene thienothiophene (DPPT-TT) that are essential for the charge transport process is studied. The main focus is on whether the transport in DPPT-TT-based organic transistors can be tuned by electric fields in the gate direction. The considered electric fields are in the range 108–1010 V m–1. We show that strong electric fields (∼109 V m–1) which are parallel to the polymer backbone can influence the reorganization energy in a Markus-type approach. Weaker electric fields parallel to the polymer backbone result in minimal changes to the reorganization energy. The coupling element of DPPT-TT shows a pronounced affinity to be influenced by electric fields in the charge transport direction independent of the field strength.

Keywords: organic electronics; Marcus model; transfer matrix elements; conductivity; mobility; field effect

Downloads

Permalink: https://www.hzdr.de/publications/Publ-25540


Years: 2023 2022 2021 2020 2019 2018 2017 2016 2015


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