Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

"Online First" included
Without submitted and only approved publications
Only approved publications

35836 Publications

An Introduction to the SPEC High Performance Group and their HPC Benchmark Suites

Juckeland, G.

The SPEC High-Performance Group (HPG) develops benchmarks that:

  • represent large, real applications, in scientific and technical computing,
  • use industry standard parallel application programming interfaces (APIs), OpenMP and MPI
  • support shared-memory and message passing programming paradigms,
  • can evaluate shared-memory computers, distributed-memory computers and workstation clusters as well as traditional massively parallel processor computers,
  • come in several data sets sizes (from a few minutes to days of execution time),
  • allow for certain hand optimizations of the codes (as opposed to compiler-only optimizations)
  • Invited lecture (Conferences)
    ZKI Arbeitskreis Supercomputing Herbstreffen, 25.-26.09.2018, Freiburg, Deutschland

Publ.-Id: 27985

Is It Here/There Yet? - Real Life Experiences of Generating/Evaluating Extreme Data Sets Around the World

Juckeland, G.; Huebl, A.; Bussmann, M.

Large scale simulations easily produce vast amounts of data that cannot always be evaluated in-situ. At that point parallel file systems come into play, but their per node performance is essentially limited to about the speed of a USB 2.0 thumb drive (e.g. the Spider file system at OLCF provides over 1 TB/s write bandwidth, but with 18000+ nodes of Titan writing simultaneously, this number is reduced to about 50 MB/s per node). Making the most out of such a limited resource requires I/O libraries that actually scale. In addition such libraries also offer on the fly data transformations (e.g. compression) to better utilize the raw I/O bandwidth, albeit, opening a new can of worms by trading compression throughput with compression ratios for performance. We will present a detailed study of I/O performance and various compression techniques at OLCF and compare them against smaller local I/O installations, demonstrating the highest achieved I/O performance for real world applications at OLCF. Furthermore, we demonstrate that the best performing I/O setup can be determined prior to starting the job based on hardware characteristics.
Now that you have your data on disk the clock starts ticking and you are fighting against the deadline until your data will be purged, since most centers only offer the high performing storage spaces on a temporary basis. Extracting all valuable information out of a petabyte sized data set requires parallel processing as well and induces wait times until the resources are available and quite naturally a lot of trial-and-error for the evaluation. The time constraint for keeping the temporary data becomes even more troublesome when trying to compare multiple large simulations that naturally have a delay of multiple days until they are scheduled and write their results. And ideally analysis could embrace the data of multiple simulations of a quarterly accounted, yet year-long computing campaign. Another challenge for actually conducting scientific discoveries comes when utilizing multiple compute sites. This seems to be rather usual for research groups as they will use all the compute clock cycles they can get wherever that may be. For comparative studies the data sets now need to be available at the same time for analysis, e.g. via archiving solutions or transfer to one location. The achievable transfer bandwidth between data centers is in our experience still much lower than expected. The talk will also present on the experiences of evaluating petabyte sized data sets in such a diverse environment.

  • Lecture (Conference)
    Extreme Data Workshop 2018, 18.-19.09.2018, Jülich, Deutschland
  • Open Access Logo Contribution to proceedings
    Extreme Data Workshop 2018, 18.-19.09.2018, Jülich, Deutschland
    Extreme Data Workshop 2018 Forschungszentrum Jülich, 18 – 19 September 2018 Proceedings, Juelich: FZ Jülich GmbH Zentralbibliothek, Verlag, 17-18
    DOI: 10.14278/rodare.71


Publ.-Id: 27984

Non-invasive multimodal monitoring of transport and storage containers for spent fuel

Wagner, M.; Rachamin, R.; Schmidt, S.; Fiß, D.; Reinicke, S.; Kratzsch, A.; Hampel, U.

Until the availability of a final nuclear waste disposal in deep geological formations, spent fuel has to be safely stored for several decades in transport and storage containers, which are qualified for dry intermediate storage of spent fuel assemblies. There is a great interest in monitoring those containers in order to get aware of any changes occurring to the inventory. Getting information from the interior of the massive steel containers with 48 cm thick walls is very difficult. For this reason, we assess the possibility of detecting changes to the spent nuclear fuel distribution in the containers by combining different non-invasive measurement principles. These include thermography of the outer container walls, analysis of the gamma and neutron radiation field from the spent fuel, imaging of the inventory using transmission and scattering of cosmic muons, acoustic spectrometry including vibration analysis and sound emission analysis for detecting cracks of the fuel rods. For some of these techniques inverse problems must be solved in order to localize the detected changes. For the moment, we employ distinct numerical simulation approaches to assess the potential of the proposed methods. Moreover, we perform comparative experiments at downscaled test facilities. Eventually, we shall develop a technically applicable and reliable monitoring concept.

Keywords: inverse problem; muon imaging; radiation measurement; thermography

  • Contribution to proceedings
    9th World Congress on Industrial Process Tomography, 02.-06.09.2018, Bath, United Kingdom
  • Poster
    9th World Congress on Industrial Process Tomography, 02.-06.09.2018, Bath, United Kingdom

Publ.-Id: 27983

Simulation-based investigation of suitability of thermography and muon flux measurements for non-invasive monitoring of transport and storage containers for spent fuel

Wagner, M.; Rachamin, R.; Schmidt, S.; Fiß, D.; Reinicke, S.; Kratzsch, A.; Hampel, U.

The search for a radioactive waste repository in deep geological formations is still ongoing in Germany. Until the availability of a long-term storage spent fuel has to be stored in transport and storage containers which are qualified for the dry intermediate storage of spent fuel assemblies. In Germany, these containers are of the type CASTOR V/19 (PWR fuel assemblies) [1] or CASTOR V/52 (BWR fuel assemblies) which has a maximum permissible operating time of 40 years, at the moment. A prolonged intermediate storage of the spent fuel may exceed this period. The knowledge about the long-term behavior of the spent fuel in these containers is very limited. Therefore, there is a great interest in a non-invasive monitoring long-term of the container inventory. This is in the focus of the collaborative project DCS-MONITOR, which was already introduced in more details e. g. in [2]. The range of possible methods is very limited as it is not possible to open the cask or to insert sensors and on the other hand because of the massive walls of the cask, which hamper any non-intrusive access. Within the project gamma and neutron radiation, muon radiography, thermography, and acoustic spectrometry are investigated. In this paper, muon radiography and thermography are discussed.

Keywords: intermediate storage; container monitoring; thermography; radiation measurement; muon imaging

  • Contribution to proceedings
    49th Annual Meeting on Nuclear Technology (AMNT 2018), 29.-30.05.2018, Berlin, Deutschland
  • Lecture (Conference)
    49th Annual Meeting on Nuclear Technology (AMNT 2018), 29.-30.05.2018, Berlin, Deutschland

Publ.-Id: 27982

Application of SEM-based quantitative mineralogical analysis in the development of proxies for provenance and transport mechanisms of modern stream sediments

Rütters, S.; Tolosana-Delgado, R.; Gutzmer, J.; Kallmeier, Enrico

Provenance analyses of stream sediments mostly rely on analytical methods such as bulk sediment geochemistry, mineralogy (provided by XRD) and single grain analysis. In this study, we focus on automated mineralogy by Mineral Liberation Analyser (MLA), as a potentially powerful tool for sediment provenance studies. The MLA combines backscattered electron (BSE) imaging with energy dispersive X-ray spectrometry (EDS) generating compositional data for all measured sediment particles (in this study, i.e. 20000 to 60000 grains and the including sub-grains). Resultant data include particle and mineral grain parameters (i.e. size and shape) as well as the mineralogical composition and properties (e.g. elemental composition, density) of each particle and its individual constituting mineral grains. Necessary, robust statistical analyses are part of the study, to maximize the use of the voluminous set of data provided by MLA. These statistical analyses unveil trends and dependencies in suites of related samples. This is illustrated here in a case study. We combine bulk geochemistry, XRD and MLA analyses. On the one hand, in order to make a comparison of the selected methods, and on the other hand, to ensure the quality and to critically assess the benefit of MLA data.
The study area is located in the Vogtland region of the Free State of Saxony (Germany). The bedrock mainly consists of Variscanaged basement rocks. These rocks comprise plutonic (i.e. different types of granite) and metamorphic units (mica schists, phyllites and quartzites), which are very well studied.
With first results of the study, it becomes apparent that changes in provenance and transport features of the unconsolidated sediments are easily identified, based on the modal mineralogy, geochemical changes and grain-parameter patterns. Using the MLA we can detect and calculate the relative composition and amount of anthropogenic contamination within the sediment. Furthermore, mixing of the material is calculated with respect to the relationship between lithological changes and the river path. The examination of shape features on single grains, such as potential marks of corrosion, leaching, abrasion and fractionation, provide the possibility to implement efficient proxies, which can be related to weathering and transport mechanisms.

  • Contribution to proceedings
    GEOBONN 2018, 02.-06.09.2018, Bonn, Germany
  • Lecture (Conference)
    GEOBONN, 03.09.2018, Bonn, Germany

Publ.-Id: 27981

Extreme multi-valence states in mixed actinide oxides

Epifano, E.; Naji, M.; Manara, D.; Scheinost, A. C.; Hennig, C.; Lechelle, J.; Konings, R. J. M.; Gueneau, C.; Prieur, D.; Vitova, T.; Dardenne, K.; Rothe, J.; Martin, P. M.

In order to assure the safety of oxide-fuel based nuclear reactors, the knowledge of the atomic-scale properties of U1-yMyO2±x materials is essential. These compounds have complex chemical properties, originating from the fact that the earlier actinoids uranium, neptunium, plutonium and americium as well as fission-derived rare earths may occur in different oxidation states. In these mostly ionic materials, aliovalent cationic configurations can induce variation of the oxygen stoichiometry, with dramatic effects on the thermal properties of the fuel. First studies on U1-yAmyO2±x compounds indicated that these materials exhibit particularly complex electronic and local-structure configurations. Here we present an in-depth study of this solid solution, by combining XRD, XAS and Raman spectroscopy to study U1-yAmyO2±x oxides over a wide compositional domain. We present for the first time evidence of the co-existence of four different cations in a fluorite U1-yMyO2±x compound and we illustrate the complex atomic-scale arrangements induced by these extreme multi-valence states.

Keywords: EXAFS; XANES; uranium; americium; fluorite; nuclear fuel; oxidation state; structure

Publ.-Id: 27980

Advanced proxies for provenance, erosion and transport mechanisms of modern stream sediments – An application of SEM-based quantitative mineralogical analysis

Rütters, S.; Tolosana-Delgado, R.; Gutzmer, J.

In order to analyse stream sediments for provenance with respect to erosion and transport mechanisms, several methods are established (e.g. bulk sediment geochemistry, mineralogy (provided by XRD) and indicator mineral analysis). In this study, we make use of automated mineralogy by Mineral Liberation Analyser (MLA) as a potentially tool to advance sediment provenance studies.
The MLA combines backscattered electron (BSE) imaging with energy dispersive X‐ray spectrometry (EDS) generating compositional data each sediment particles of the sample. The provided data include particle as well as mineral grain parameters (i.e. size and shape) as well as the mineralogical composition and properties (e.g. elemental composition, density) of each particle (including individual constituting mineral grains). The aim is to join the provided parameters in a holistic model including statistical automatisms. In order to ensure a valid combination of the heterogenic and voluminous set of data provided by MLA, robust statistical analyses are needed. These statistical analyses unveil trends and dependencies in suites of related samples. Furthermore, in this study bulk geochemistry and XRD measurements are integrated to guaranty the quality of the introduced method and subsequently to critically assess the benefit of the measurement.
The study area is located in the Vogtland region of the Free State of Saxony (Germany). The variscan bedrocks comprise plutonic (i.e. different types of granite) and metamorphic units (mica schists, phyllites and quartzites), which are very well studied. Especially since, the Vogtland and the neighbouring Erzgebirge are well known for the occurrence of granite‐related mineral systems, represented as polymetallic deposits (skarn‐, vein‐, stockwork‐, and greisen‐type). In addition, this area is menial populated, suggesting a restricted anthropogenic contaminations of the stream sediment.
First results of this study, give rise for a clear improvement in the detection of lithological changes of the source rock composition and transport features of the unconsolidated sediments. This can be easily identified, based on the modal mineralogy, geochemical changes and grain‐parameter patterns. In addition, mixing of the material can be calculated with respect lithological changes along the river path. Another issue, is to detect the anthropogenic contamination of the sampled material and to balance the impact to the chemical composition.

  • Open Access Logo Contribution to proceedings
    WGSG Dublin IV, 27.-29.06.2018, Dublin, Ireland
  • Poster
    WGSG Dublin IV, 27.-29.06.2018, Dublin, Ireland

Publ.-Id: 27979

How Schizophyllum commune and Leucoagaricus naucinus meddle in radiometal migration

Raff, J.; Wollenberg, A.; Merroun, M.; Günther, A.; Stumpf, T.

Different radiometals occur geogenically in nature. Others may be released while their industrial and medical application or accidentally e.g., after a nuclear power plant failure. In nature, their migration behavior and their possible entrance into the food chain is highly influenced by the geochemistry and the biology. Not only since the Chernobyl accident it is well known that different fungi are able to accumulate significant amounts of heavy metals and radiometals in their cells. Besides that, is was described that fungi interact with radiometals by sorption, complexation and/or biomineralization. Fungi as organic decomposers are widespread, and grow not only in the topsoil, but may reach also the subsoil and the root-free zone. They can form a large biomass and can get at least several hundred years old. All these properties taken together, fungi have high potential for precautionary radiation protection by immobilizing radionuclides in their biomass. But prior to application it is crucial to get a detailed molecular understanding of the interaction of radiometals with fungi.
Based on literature and own experiments the two fungi Schizophyllum commune and Leucoagaricus naucinus were chosen to investigate their interaction with U, Eu, Cs and Sr, with Eu serving as analogue for trivalent actinides. By applying different experimental and analytical methods such as mass spectrometry, fluorescence spectroscopy, batch and column experiments as well as electron microscopy, their interaction with radiometals was investigated qualitatively and quantitatively. The results demonstrate fundamental differences of both fungi regarding the amount of bioassociated radiometals and the kind of their interaction.

Keywords: Radinuclide; fungi; bioassociation

  • Lecture (Conference)
    17th Symposium on Remediation, 01.-02.10.2018, Jena, Deutschland

Publ.-Id: 27978

Automated mineralogy as efficient tool for provenance analysis of stream sediments and mineral exploration

Rütters, S.; Gutzmer, J.; Kallmeier, E.

The Erzgebirge and neighboring Vogtland, are well known for the occurrence of granite-related mineral systems, represented as polymetallic skarn-, vein-, stockwork- and greisen-type deposits. Renewed exploration has been motivated by remarkable amounts of Sn, In and Li contained in some of the deposits. Some of the deposits currently explored have been exploited for centuries – others have been known for decades. The regional and local geological setting of these deposits is very well understood, especially concerning the magmatic and metamorphic lithological units. Therefore, the Erzgebirge and Vogtland are an excellent study area to test innovative exploration methods, such as the use of quantitative mineralogical data from modern stream sediments as a proxy for granite-related mineralization. The present study aims to provide such proxies of provenance and transport mechanisms by using automated mineralogy. The approach includes a grain-size window as wide as possible, and at the same time optimizes the statistical evaluation of both bulk sediment composition and single grain analyses.
Geochemical data from 209 samples of modern first- and higher-order streams are provided. To enhance the exploratory potential of the sand-sized sediments c.100 samples were analyzed, with a Mineral Liberation Analyzer (MLA). The MLA combines the information of Backscattered Electron Images (BSE) and Energy Dispersive X-ray-Spectrometry (EDS) to provide data of different features, such as mineralogy, mineral chemistry, particle size and particle shape. Results illustrate that the true potential of automated mineralogy data for mineral exploration goes far beyond the big database of quantitative data - in comparison to the standard petrographic methods such i.e. point counting. Rather, it is the possibility to implement efficient routines that allow to discover and track changes in mineralogy, mineral grain sizes, shapes or mineral associations within a complex population of sediment samples.

  • Contribution to proceedings
    European Geosciences Union General Assembly 2018, 08.-13.04.2018, Vienna, Austria
  • Poster
    European Geosciences Union General Assembly 2018, 10.04.2018, Vienna, Austria

Publ.-Id: 27977

Controlling shallow- and deep-level dopants in silicon nanowires via non-equilibrium processing

Berencén, Y.; Prucnal, S.; Wang, M.; Hübner, R.; Möller, W.; Schönherr, T.; Bilal Khan, M.; Glaser, M.; Georgiev, Y. M.; Erbe, A.; Lugstein, A.; Rebohle, L.; Helm, M.; Zhou, S.

Semiconducting nanowires (NWs) hold promises for functional nanoscale devices [1]. Although several applications have been demonstrated in the areas of electronics, photonics and sensing, the doping of NWs remains challenging. Ion implantation is a standard doping method in top-down semiconductor industry, which offers precise control over the areal dose and depth profile as well as allows for the doping of all elements of the periodic table even beyond their equilibrium solid solubility [2]. Yet its major disadvantage is the concurrent material damage. A subsequent annealing process is commonly used for the healing of implant damage and the electrical activation of dopants. This step, however, might lead to the out-diffusion of dopants and eventually the degradation of NWs because of the low thermal stability caused by the large surface–area-to-volume ratio.

In this work, we report on non-equilibrium processing for controlled doping of drop-casted Si/SiO2 core/shell NWs with shallow- and deep-level dopants below and above their equilibrium solid solubility. The approach lies on the implantation of either shallow-level dopants, such as B and P, or deep-level dopants like Se followed by millisecond flash lamp annealing. In case of amorphization upon high-fluence implantation, recrystallization takes place via a bottom-up template-assisted solid phase epitaxy. Non-equilibrium Se concentrations lead to intermediate-band Si/SiO2 core/shell NWs that have room-temperature sub-band gap photoresponse when configured as a photoconductor device [3]. Alternatively, the formation of a cross-sectional p-n junction is demonstrated by co-implanting P and B in individual NWs at different depth along the NW core.

[1] Peidong Yang, Ruoxue Yan, and Melissa Fardy, Nano Lett. 2010, 10, 1529–1536
[2] Michiro Sugitani, Rev. Sci. Instrum. 2014, 85, 02C315
[3] Y. Berencén, et al. Adv. Mater. Interfaces 2018, 5, 1800101

Keywords: Nanowires; ion implantation; flash lamp annealing; hyperdoping; solid phase epitaxy

  • Lecture (Conference)
    SYMPOSIUM M: Organized nanostructures and nano-objects: fabrication, characterization and applications, 17.-20.09.2018, Warsaw University of Technology, Poland

Publ.-Id: 27976

Formation of n- and p-type regions in individual Si/SiO2 core/shell nanowires by ion beam doping

Berencén, Y.; Prucnal, S.; Möller, W.; Hübner, R.; Rebohle, L.; Schönherr, T.; Bilal Khan, M.; Wang, M.; Glaser, M.; Georgiev, Y. M.; Erbe, A.; Lugstein, A.; Helm, M.; Zhou, S.

A method for cross-sectional doping of individual Si/SiO2 core/shell nanowires (NWs) is presented. P and B atoms are laterally implanted at different depths in the Si core. The healing of the implantation-related damage together with the electrical activation of the dopants takes place via solid phase epitaxy driven by millisecond-range flash lamp annealing. Electrical measurements through a bevel formed along the NW enabled us to demonstrate the concurrent formation of n- and p-type regions in individual Si/SiO2 core/shell NWs. These results might pave the way for ion beam doping of nanostructured semiconductors produced by using either top-down or bottom-up approaches.

Keywords: nanowires; ion beam doping; flash lamp annealing


Publ.-Id: 27975

First time in vivo assessment of sigma-1 receptor binding (Sig-1R) in the brain of unmedicated acute major depressive disorder (MDD) using the novel Sig-1R-specific radioligand (-)-[F-18]Fluspidine and PET

Meyer, P. M.; Strauß, M.; Becker, G. A.; Hesse, S.; Bednasch, K.; Ettrich, B.; Zientek, F.; Rullmann, M.; Luthardt, J.; Fischer, S.; Patt, M.; Wünsch, B.; Brust, P.; Sabri, O.

The Sig-1R is a chaperone protein localized at the endoplasmatic reticulum (ER) that can translocate under ER stress, a mechanism which is critically involved in the pathophysiology of MDD. In order to investigate the pathophysiology of Sig-1R regulation in MDD, for the first time we quantitatively assessed Sig-1R binding in the brain of unmedicated, acute MDD and compared it with healthy controls (HC) using the novel radioligand (-)-[F-18]Fluspidine and PET.
Unmedicated, moderate to severe, acute MDD (n=12; 33±13ys; 6 males: HAMD: 19.0±4.3; MDD+ with family histora [n=6] and MDD- without family history of depression [n=6]), were investigated using(-)-[F-18]Fluspidine PET (300 MBq, ECAT Exact HR+) and compared with age-/sex-matched healthy controls (HC; n=9; 37±16ys [n.s.]; 4 males [n.s]). Distribution volume parameters (VT) were determined using full pharmacokinetic modelling (2TCM, metabolite correction). Regional VOI-analyses were carried out.
Compared with HC, in MDD, VT was significantly higher within the ncl. caudatus, ncl. accumbens, fronto-temporo-parieto-occipital and cingulate cortices, insula, amygdala, thalamus and midbrain/raphe (+15 to +24%, P<0.05). Compared with MDD-, in MDD+, VT was higher in the fronto -temporo and cingulate cortices, insula, hippocampus, putamen, thalamus (P<0.05). There was an inverted U-relationship between the severity of MDD (HAMD) and VT in the fronto-temporo-parietal and posterior cingulate cortices and thalamus (P<0.05).
Using (-)-[F-18]Fluspidine PET, we demonstrate for the first time higher Sig-1R binding in meso-striato-cortico-limbic and paralimbic brain regions of unmedicated, acute MDD. Higher Sig-1R binding in MDD+, compared with MDD-, may express different subtypes of depression. Increased Sig-1Rs in acute MDD and the inverted U-relationship between severity and Sig-1R may reflect neuroadaptive uptregulation of Sig-1R counteracting ER stress that is exhausted in the severest stages of MDD leading to apoptosis.

  • Lecture (Conference)
    56. Jahrestagung der DGN, 18.-21.04.2018, Bremen, Deutschland
  • Abstract in refereed journal
    Nuklearmedizin 56(2018), V65

Publ.-Id: 27974

Ion acceleration with on-shot monitored ultra-high contrast using the DRACO Petawatt laser facility

Ziegler, T.; Bernert, C.; Bock, S.; Brack, F.-E.; Bussmann, M.; Garten, M.; Kraft, S.; Kroll, F.; Metzkes-Ng, J.; Obst, L.; Oksenhendler, T.; Rehwald, M.; Schlenvoigt, H.-P.; Schramm, U.; Zeil, K.

Laser-driven ion acceleration promises to provide a compact solution for demanding applications like particle therapy, proton radiography or inertial confinement research. Controlling the beam parameters to achieve these goals is currently pushing the frontier of laser driven particle accelerators.
We present an overview of recent achievements at the high power ultra-short pulse laser source DRACO at the HZDR in Dresden (Germany). The laser system was recently upgraded by new front end components and an additional Petawatt (PW) amplifier stage, finally providing high contrast pulses of 30J within 30fs at 1 Hz pulse repetition rate.
The performance of the plasma acceleration is strongly dependent on the complex pre-plasma formation process at the target front surface which is determined by the temporal intensity contrast. Plasma mirror setups have proven to be a valuable tool to significantly improve the temporal contrast by reducing pre-pulse intensity and steepening the rising edge of the main laser pulse. Re-collimating single plasma mirror devices have therefore been implemented into the Draco laser beam lines, enabling investigation of laser proton acceleration and proton energy scaling within the TNSA regime using ultra-thin foil targets.
The results of the simultaneously measured proton emission energies in laser forward direction, laser backward direction and the temporal contrast, measured on a single-shot base by means of self-referenced spectral interferometry with extended time excursion (SRSI-ETE) at unprecedented dynamic and temporal range, will be presented.

  • Poster
    45th Conference on Plasma Physics, 02.-06.07.2018, Prague, Czech Republic

Publ.-Id: 27973

All-optical shaping of laser-driven proton beam profiles

Ziegler, T.; Obst-Huebl, L.; Brack, F.-E.; Branco, J.; Bussmann, M.; Cowan, T. E.; Curry, C. B.; Fiuza, F.; Garten, M.; Gauthier, M.; Göde, S.; Glenzer, S. H.; Huebl, A.; Irman, A.; Kim, J. B.; Kluge, T.; Kraft, S.; Kroll, F.; Metzkes-Ng, J.; Pausch, R.; Prencipe, I.; Rehwald, M.; Rödel, C.; Schlenvoigt, H.-P.; Schramm, U.; Zeil, K.

Extreme field gradients intrinsic to relativistic laser plasma interactions enable compact MeV proton accelerators with unique bunch characteristics, yet complicate direct proton beam control. Only complex micro-engineering of the plasma accelerator itself and limited adoption of conventional beam optics, so far provided access to global beam parameters as direction and divergence. Here we present a novel, counter-intuitive, yet readily applicable all-optical approach to imprint detailed spatial information from the driving laser pulse to the proton bunch. In a series of experiments, the spatial profile of the energetic proton bunch was found to exhibit identical features as the fraction of the laser pulse passing around a target of limited size. The formation of quasi-static electric fields in the beam path by ionization of residual gas in the experimental chamber results in asynchronous information transfer between the laser pulse and the naturally delayed proton bunch. Essentially acting as a programmable memory, these fields provide access to a new level of proton beam manipulation.

  • Poster
    8th Conference of the International Committee on Ultrahigh Intensity Lasers, 09.-14.09.2018, Lindau, Germany
  • Lecture (Conference)
    SPIE Optics + Optoelectronics 2019, 01.-04.04.2019, Prag, Tschechische Republik

Publ.-Id: 27972

A fine future - Flotation in times of circular economy and energy transition

Rudolph, M.

The invention of flotation about 140 years ago was one of the great achievements of modern processing technology. For many metallic/mineral raw materials, processing without a flotation stage would be unthinkable. This article presents the especially important topics in the field of basic research and technological development of flotation in times of the circular economy and energy transition.

Keywords: Flotation; Circular Economy; Energiewende

  • Open Access Logo AT Mineral Processing 59(2018), 56-64

Publ.-Id: 27971

Heterogeneity of γH2AX foci increases in ex vivo biopsies relative to in vivo tumors

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

The biomarker for DNA double stand breaks, gammaH2AX (γH2AX), holds a high potential as an intrinsic radiosensitivity predictor of tumors in clinical practice. Here, two published γH2AX foci datasets from in and ex vivo exposed human head and neck squamous cell carcinoma (hHNSCC) xenografts were statistically re-evaluated for the effect of the assay setting (in or ex vivo) on cellular geometry and the degree of heterogeneity in γH2AX foci. Significant differences between the nucleus areas of in- and ex vivo exposed samples were found. However, the number of foci increased linearly with nucleus area in irradiated samples of both settings. Moreover, irradiated tumor cells showed changes of nucleus area distributions towards larger areas compared to unexposed samples, implying cell cycle alteration after radiation exposure. The number of residual γH2AX foci showed a higher degree of intra-tumoral heterogeneity in the ex vivo exposed samples relative to the in vivo exposed samples. In the in vivo setting, the highest intra-tumoral heterogeneity was observed in initial γH2AX foci numbers (foci detected 30 min following irradiation). These results suggest that the tumor microenvironment and the culture condition considerably influence cellular adaptation and DNA damage repair.

Keywords: radiation; predictive biomarker; DNA damage response; mixed model statistics

Publ.-Id: 27970

An endorectal balloon reduces patient-reported GI toxicity in postop radiotherapy of prostate cancer

Holscher, T.; Rentsch, A.; Zastrow, S.; Wirth, M.; Ahmad, A.; Krause, M.; Troost, E.

Purpose or Objective
In dose-escalated radiotherapy (RT) of prostate cancer late rectal toxicity is one of the dose limiting factors. In primary RT, an endorectal balloon (RB) has been shown to reduce the dose to parts of rectum and anus, stabilize prostate position and may therefore be a means to improve therapeutic ratio. In postoperative radiotherapy the effect of RB is less well-known, in general a dose of <70 Gy is applied and therefore no clinical outcome data regarding the benefit of a RB is available.
The aim of this retrospective study was to assess the patient-reported late rectal toxicity (GItox) 3, 12, and 24 months after RT in postoperative prostate cancer patients receiving a daily RB, compared to an earlier cohort, which was treated without RB.
Material and Methods
We identified all patients who received postoperative radiotherapy (66 Gy in 33 fractions) after radical prostatectomy, had no nodal or distant metastases and at least one follow-up visit. In those treated between 2008 and 2013, no RB was applied whereas between 2014 and 2016, a RB was routinely applied. All patients were followed with the same set of questionnaires and outpatient visits. Results where compared and analysed by Chi²-Test (SPSS 23.0).
In total, 433 patients were retrieved, of whom 194 were treated with and 239 patients without RB. The patients were well balanced according initial NCCN risk and other confounding factors. The maximum patient reported GItox in the first 2 years after RT was low: 75,5%, 20,8%, 3,7 %, 0 % reported no, grade 1 (G1), G2 and G3 GItox, respectively. The prevalence of rate of G1+ GItox was 16,5%, 15,1% and 18,0% at 3, 12, and 24 months, respectively. No GItox within 2 years occurred in 71,1% patients without RB versus 80,9% with RB. G1+ GItox was reported in 28,5% without RB and in 19,1% with RB. G2 GITox was reported by 13 (5,4%) patients without and by 3 (1,5%) with RB. These results are statistically significant at p<0,025.
This retrospective data show a significant and clinically relevant reduction of GItox after postoperative RT for prostate cancer using an endorectal balloon. A prospective randomized trial is currently being prepared.


Publ.-Id: 27969

A concept to personalize radiation oncology: Predicting cell-specific survival prior to treatment

Oesten, H.; von Neubeck, C.; Löck, S.; Enghardt, W.; Krause, M.; Mcmahon, S.; Grassberger, C.; Paganetti, H.; Lühr, A.

Material and Methods
Based on a previously developed mechanistic radiation response model of DNA repair and cell survival (CS) prediction for normal tissue cells, we simulated measured radiobiological parameters (α and β) of 19 in vitro cancer cell lines (skin, lung, brain). The radiation model incorporated four cell-specific parameters: number of chromosomes, p53 mutation status, cell-cycle distribution and the effective genome size (GS). Only the first three input parameters were experimentally available; the latter was obtained by minimizing the difference between the simulated and measured α and β values. A parametrization of the GS as a function of the cells’ chromosome number and nucleus volume was proposed. The use of these input parameters was validated by comparing the simulated outcome of time-dependent γH2AX data over 24h with independent experimental datasets.
Overall good agreement between simulated and measured in vitro cancer CS curves was achieved (Fig. 1). The measured β values increased quadratically with the obtained GS (R2=0.81) irrespective of other cell-specific parameters (Fig. 2b). The measured α values increased linearly with GS manifesting different slopes distinguishable into the cells’ p53 mutation status (Fig. 2a). Measured α and β values were predictable based on GS with a one-sigma uncertainty: σ=0.04Gy-1 for α and σ=0.01Gy-2 for β. The GS correlated (R2=0.70) with the number of chromosomes for all but four cell lines. The detailed cell-specific cell cycle distribution had a negligible impact on α and β. Measured time-dependent γH2AX data were consistent with the repair kinetics simulations (R2=0.95).
A mechanistic model for radiation response of normal human cells was successfully modified to simulate measured in vitro CS of 19 cancer cell lines. Independent of cancer entity, the radiobiological value β was predictable only with known GS while the prediction of α additionally required at least knowledge of the p53 mutation status. An observed correlation of GS with the number of chromosomes and nucleus size, both clinically accessible from a biopsy prior to treatment, may facilitate individualized radiotherapy based on cell-specific survival prediction.

Publ.-Id: 27968

Terahertz Generation with Ballistic Photodiodes under Pulsed Operation

Müller-Landau, C.; Malzer, S.; Weber, H. B.; Döhler, G. H.; Winnerl, S.; Burke, P.; Gossard, A. C.; Preu, S.

We investigate high field and ballistic carrier transport in a 1.55 μm photomixing device based on pin-diodes by time resolved terahertz (THz) spectroscopy. The device consists of 3 stacked In(Al)GaAs pin diodes (n-i-pn-i-p superlattice) attached to a broadband logarithmic-periodic antenna. Each pin diode is optimized for exhibiting ballistic transport and a reduced transit time roll-off. Ballistic transport signatures could be confirmed directly in these experiments. The data are compared with results from continuous-wave (CW) experiments and from simulations both supporting our theoretical expectations. It is demonstrated that n-i-pn-i-p superlattice photomixers are also efficient THz emitters under pulsed operation, showing a maximum THz field strength of ∼0.5 V/cm (peak to peak) at 30 mW average optical power.

Keywords: THz generation; time-domain spectroscopy; photomixing; ballistic transport


Publ.-Id: 27967

Picosecond-scale Terahertz pulse characterization with field-effect transistors

Regensburger, S.; Winnerl, S.; Klopf, J. M.; Lu, H.; Gossard, A. C.; Preu, S.

Precise real-time detection of Terahertz pulses is a key requirement in Terahertz communication technology,
non-destructive testing, and characterization of pulsed Terahertz sources. We experimentally evaluate the speed
limits of Terahertz rectification in field-effect transistors using the example of pulses from a free-electron laser. We develop an improved model for the description of these Terahertz pulses and demonstrate its validity experimentally by comparison to spectroscopic data as well as to expectation values calculated from free-electron laser physics.
The model in conjunction with the high speed of the detectors permits the detection of an exponential rise time of the pulses as short as 5 ps despite a post detection time constant of 11 and 14 ps for a large area and an antenna-coupled detector, respectively. This proves that field-effect transistors are excellent compact, roomtemperature Terahertz detectors for applications requiring an intermediate frequency bandwidth of several tens of GHz.

Keywords: THz detector; field-effect transistor; pulse diagnostics


Publ.-Id: 27966

Scalable Multi-Platform PIC Simulations as an Open Science Service

Huebl, A.; Pausch, R.; Widera, R.; Garten, M.; Debus, A.; Goethel, I.; Matthes, A.; Worpitz, B.; Starke, S.; Kelling, J.; Kossagk, S.; Bastrakov, S.; Kluge, T.; Juckeland, G.; Schramm, U.; Cowan, T. E.; Bussmann, M.

PIConGPU is a fully open, community-driven, 3D and 2D3V particle-in-cell code for the age of heterogeneous, many-core driven supercomputing. Developed in a single source C++ code base, PIConGPU supports both "traditional" CPU architectures as well as modern and highly parallel architectures such as OpenPOWER, Xeon Phi, and Nvidia GPUs.

PIConGPU has shown to be suitable for production runs on the full system size of TOP5 clusters such as Titan (ORNL) and Piz Daint (CSCS). Machines like those enable few-hour turnarounds for full 3D3V simulations on complex studies such as laser-ion acceleration from mass-limited targets, long-scale laser-wakefield acceleration with high bunch charges, and hybrid acceleration schemes. The resulting output of systematic parameter scans (PBytes+) raises a severe challenge for data centers. We address these issues with modern IO frameworks, performance modeling, and in situ data reduction techniques. Using such online methods we can investigate a wide range of observables relevant for experiments and run dozens of simulations at the same time frame as an experimental beam time.

PIConGPU is further complemented by modern methods for photon generation, transport, as well as X-ray interaction. This simulation framework aims to provide documented, installable, and re-usable software components for the community, well-suited for open data (openPMD) and open science workflows without restrictions. Latest developments include a python-centric, extensive framework for specific experiments, which provides all of the above in an intuitive, non-expert user interface.

Keywords: PIConGPU; Scalability; performance-portability; Open Source; Open Science; FOSS; Open Data; In Situ processing; SaaS; GPU; Big Data

  • Lecture (Conference)
    18th Advanced Accelerator Concepts Workshop (AAC 2018), 12.-17.08.2018, Breckenridge (CO), United States of America
    DOI: 10.5281/zenodo.1345080
  • Poster
    18th Advanced Accelerator Concepts Workshop (AAC 2018), 12.-17.08.2018, Breckenridge (CO), United States of America

Publ.-Id: 27965

Data Analysis and Simulations in Exascale Computing: Quō vādis?

Huebl, A.; Ehrig, S.; Bussmann, M.

We are less than three years apart from the first, double precision Exa-Flop/s supercomputers. Already today, our scientific software stacks are facing the challenge to run efficiently on a potpourri of architectures. But the real troubles might await us at the choke points of extreme data rates, where traditional workflows of data acquisition, filtering, processing and subsequent long-term storage might not be able to be sustained anymore.

How would you like to express your scientific algorithms in a world where Flop/s are increasingly cheap, yet hard to achieve, but data movement and especially data at rest is increasingly in-proportionally expensive? Would you be OK to throw data away and measure twice? Can we in situ compute results with a different prepared question instead of waiting for an always-full and quickly-purged filesystem? How do we ensure reproducibility? How large a mix of programming languages and double-implementations of algorithms can we burden before we are running out of developers (due to lack of maintainability)?

This talk will present our vision for the next years of data-driven scientific computing. Based on our experience with single-source, performance-portable C++ HPC libraries, we will present zero-overhead C++ abstractions that spare code-duplication. Together with light-weight code coupling, possible directions for analyzing resulting data rates are discussed on examples from laser-driven particle accelerator research. With such meta-programming approaches, an underestimated risk lies in cutbacks for both development workflows and user interactivity at runtime, which we want to openly change with interactive Cling-assisted execution in modern environments such as Jupyter, for which we recently enabled CUDA C++ capabilities.

Keywords: Exascale; C++; Scientific Computing; Open Data; Interactivity; GPU; Manycore; Open Source

  • Invited lecture (Conferences)
    ROOT User's Workshop, 10.-13.09.2018, Sarajevo, Bosnien und Herzegowina
    DOI: 10.5281/zenodo.1412537

Publ.-Id: 27964

Open, Any-Platform, Leadership-Scale Particle-in-Cell Simulations for Everyone

Huebl, A.; Widera, R.; Pausch, R.; Garten, M.; Debus, A.; Goethel, I.; Matthes, A.; Worpitz, B.; Starke, S.; Kelling, J.; Kossagk, S.; Bastrakov, S.; Kluge, T.; Juckeland, G.; Schramm, U.; Cowan, T. E.; Bussmann, M.

PIConGPU is a fully open, community-driven, 3D and 2D3V particle-in-cell code for the age of heterogeneous, many-core driven supercomputing. Running from a single source C++ code base PIConGPU supports both "legacy" CPU architectures as well as modern and highly parallel architectures such as OpenPOWER, XeonPHI, and Nvidia GPUs.

Especially the latter enable few-hour turnaround full 3D simulations for complex studies such as laser-ion acceleration. The resulting dramatic demands in post-processing (PBytes+) are efficiently addressed with implemented in-situ data reduction techniques. Those allow asking e.g. for a wide range of observables relevant for experiments - up to 100x during the time frame of an actual beam time. This is complemented by modern methods for photon generation, transport, and X-ray interaction.

Driving, re-using and publishing performance-portable libraries, PIConGPU aims to provide documented, installable and re-usable software components for the community, well suited for open data (openPMD) and open science workflows without restrictions. Latest developments further include a python-centric, extensive framework for specific experiments, which provides all of the above in an intuitive, non-expert user interface.

Keywords: PIConGPU; PIC; Open Software; LPA; 3D3V; particle-in-cell; performance portability; SaaS

  • Poster
    45th EPS Conference on Plasma Physics, 02.-06.07.2018, Prague, Czech Republic

Publ.-Id: 27963

openPMD - An Open Standard for Particle-Mesh Data Files

Huebl, A.; Lehe, R.; Vay, J.-L.; Grote, D. P.; Sbalzarini, I. F.; Kuschel, S.; Sagan, D.; Pérez, F.; Koller, F.; Bussmann, M.

Data fuels and substantiates scientific discoveries. Advanced particle accelerator research is no different and has an inherent need for high-rate, high-resolution data. But in recent years, generating and handling the sheer amount data that is driving our discoveries became challenging. Just to name a few: scalable output from 3D simulations breaks down for modern supercomputers, high-rate Mpixel cameras generate GByte/s for laser control and comparing even just simulations to each other is a significant, manual, error-prone process.

We present our open standard for particle and mesh based data, addressing these and more common challenges in our community. Based on state-of-the-art file formats and I/O libraries, we implement and improve scalable I/O without loosing self-description. openPMD is portable, truly self-describing, documented, forward-updatable and makes data comparable and reproducible.

openPMD tries to follow best-practices towards an open-science workflow. While the meta standard is developed in an open, reviewable, versioned technical document, a large collection of tools and bindings develop around it. We will take a look at the community that fuels openPMD, the open-source projects evolving around it, adopters in the domain of astro-physics, photon-science and classical accelerator physics and the latest updates arriving in openPMD 2.0.0 .

Keywords: openPMD; open data; open science

  • Lecture (Conference)
    SIMEX Developer Workshop, 16.04.2018, Hamburg, Deutschland
    DOI: 10.5281/zenodo.1219733
  • Lecture (Conference)
    EUCALL (SIMEX) Annual Meeting, 30.05.-01.06.2018, Prague, Czech Republic
  • Lecture (Conference)
    18th Advanced Accelerator Concepts Workshop, 12.-17.08.2018, Breckenridge (CO), United States of America
    DOI: 10.5281/zenodo.1345077

Publ.-Id: 27962

HPC as a Tool for Better Science

Huebl, A.; Juckeland, G.

While High Performance Computing (HPC) has been around for decades, it has been largely seen as a small niche for very limited scientific challenges. The cloud computing revolution had the wonderful side effect that everybody can now easily accept that certain tasks are transparently performed elsewhere. Web-based user interfaces enable an application interaction regardless of the actual location of the computation. As such more and more HPC centers offer web-portals to access their systems and applications also offer a web-based front-end, so that the obscure green font on black screen magic of a typical SSH session is hidden from the end user. This enables both new groups to use HPC systems but also provides power users a more error proof and efficient way of using installed applications. This talk showcases how this application as a service mode has changed the computing landscape in a multi-disciplinary research laboratory both from a users and an HPC operators perspective.

Keywords: HPC; Open Science; SaaS; PIConGPU

  • Invited lecture (Conferences)
    SIAM Conference on Parallel Processing for Scientific Computing, 07.03.2018, Tokio, Japan

Publ.-Id: 27961

Modeling Laser-Plasma Interaction with PIConGPU

Huebl, A.; Widera, R.; Pausch, R.; Garten, M.; Burau, H.; Matthes, A.; Worpitz, B.; Bastrakov, S.; Koller, F.; Kluge, T.; Vorberger, J.; Debus, A.; Cowan, T.; Schramm, U.; Chung, H.-K.; Bussmann, M.

Introduction into our open particle-in-cell code PIConGPU and research activities with it at HZDR.

Keywords: PIConGPU; open source; LPA

  • Invited lecture (Conferences)
    ILE Institute Seminar, 01.03.2018, Osaka, Japan

Publ.-Id: 27960

PIConGPU: Applications in Laser Ion Acceleration and Non-LTE Ionization Modeling

Huebl, A.; Widera, R.; Pausch, R.; Burau, H.; Garten, M.; Matthes, A.; Debus, A.; Kluge, T.; Bussmann, M.

We present the scientific workflow and applications in plasma physics of the performance portable, open source, 3D3V electro-magnetic, many-core particle-in-cell (PIC) code PIConGPU. With an open and modern software environment, PIConGPU is already suited for the largest available supercomputers today and has now evolved to a single-source hardware independent PIC code running on conventional x86 architectures, upcoming OpenPOWER CPUs, many-core accelerators and as before, GPUs.

Keywords: PIConGPU; workflows; open science; 3D3V simulation; OpenPOWER; Alpaka; performance-portability; LPA; laser-plasma

  • Poster
    HZDR PhD Seminar, 16.-18.10.2017, Seiffen, Deutschland

Publ.-Id: 27959

Accelerating Accelerator Research for Radiation Therapy of Tumors with PIConGPU

Huebl, A.; Kluge, T.; Schramm, U.; Bussmann, M.

Laser ion acceleration for tumor therapy requires control of the plasma acceleration process. Here we present the incredients of our first principle simulations, providing control, insight and predicting scaling laws towards efficient laser plasma acceleration.

Keywords: POF; PIConGPU; LPA; Laser-Ion Acceleration; Simulation; Accelerator; GPU

  • Poster
    POF Evaluation HZDR (Health), 09.-11.10.2017, Dresden, Deutschland

Publ.-Id: 27958

Next-Generation Simulations for XFEL-Plasma Interactions with Solid Density Targets with PIConGPU - Solutions for Predictive 3D Modeling

Huebl, A.; Widera, R.; Pausch, R.; Garten, M.; Burau, H.; Koller, F.; Kluge, T.; Vorberger, J.; Debus, A.; Cowan, T.; Schramm, U.; Chung, H.-K.; Bussmann, M.

PIConGPU reportedly is the fastest particle-in-cell code in the world with respect to sustained Flop/s. Written in performance-portable, single-source C++ we constantly push the envelope towards Exascale laser-plasma modeling. However, solving previously week-long simulation tasks in a few hours with a speedy framework is only the beginning.

This talk will present the architecture and recent additions driving PIConGPU. As we speak, we run on the fastest machines and the community approaches a new generation of TOP10 clusters. Within those, many-core computing architectures and severe limitations in available I/O bandwidth demand fundamental rethinking of established modeling workflows towards in situ-processing.

We present our ready-to-use open-source solutions and address scientific repeatability, data-reduction in I/O, predictability and new atomic modeling for XFEL pump-probe experiments.

Keywords: PIConGPU; exascale; xfel; hed; 3D simulations; laser-ion acceleration; lpa

  • Lecture (Conference)
    3rd European Advanced Accelerator Concepts Workshop, 24.-30.09.2017, Elba, Italien

Publ.-Id: 27957

Open the Exascale Tool Chest for Predictive Plasma Modelling with PIConGPU

Huebl, A.; Widera, R.; Pausch, R.; Garten, M.; Burau, H.; Kluge, T.; Debus, A.; Vorberger, J.; Chung, H.-K.; Cowan, T.; Schramm, U.; Bussmann, M.

PIConGPU is reportedly the world's fastest, electro-magnetic 3D3V particle-in-cell code. With sustained multi-PFlop/s performance and demonstrated PByte-scale I/O performance 2 this open-source PIC code is able to fully exploit the computational power provided by leadership-scale manycore HPC systems. At the same time, modern single-source C++ meta-programming enables performance-portability without the need of rewriting or maintaining code for various programming models.

Originally developed for the domain of laser-plasma acceleration, the PIConGPU project addresses today's needs for reproducible, repeatable, large-scale parameter studies and fundamentally reshapes simulation workflows towards Exascale computing. Deploying in situ analysis for observables, we bridge the ever-growing gap between computational power and post-processing (IO) capabilities. For the first time, the dramatic increase in computational power allows self-consistent coupling of 3D PIC kinetics with non-LTE plasma physics for collisional-radiative modelling towards pump-probe experiments at the European XFEL.

We present the architecture, open environment, open standards, community and physical models of our open-source software PIConGPU 4 and its applications in laser-plasma physics, XFEL-matter interaction and computational astrophysics.

Keywords: open source; exascale; picongpu; laser-plasma; pic; xfel; hed

  • Lecture (Conference)
    International Conference on Numerical Simulation of Plasmas, 18.-20.09.2017, Leuven, Belgium

Publ.-Id: 27956

Retrospective investigation of the prognostic value of the β1 integrin expression in patients with head and neck squamous cell carcinoma receiving primary radio(chemo)therapy

Cordes, N.; Ney, M.; Beleites, T.; Aust, D.; Baretton, G.; Thames, H.; Baumann, M.; Krause, M.; Löck, S.; Appold, S.

This retrospective study evaluated the expression of β1 integrins and associated proteins as prognostic markers for primary radio(chemo)therapy outcome of patients with locally advanced head and neck squamous cell carcinomas (HNSCC). Tissue microarrays were prepared from 224 HNSCC patients undergoing curative primary radio(chemo)therapy from 1996 to 2005. Staining intensities of β1 integrin and its downstream-proteins FAK, phosphorylated FAK as well as the β1 integrin ECM ligands fibronectin and collagen type-I were determined. Their association to the primary endpoint loco-regional control and the secondary endpoints overall survival and freedom from distant metastasis was analyzed by Cox regression. None of the considered molecular parameters showed a significant association with loco-regional control and freedom from distant metastasis. Patients with p16 positive tumors or tumors with a low intensity of fibronectin showed significantly higher overall survival in univariable regression. In multivariable regression including additional clinical parameters, however, these parameters were not significantly associated with overall survival. Our study in a HNSCC patient cohort treated with primary radio(chemo)therapy does not reveal a prognostic value of β1 integrin expression.

Keywords: Head and neck squamous cell carcinoma; radiochemotherapy; β1 integrin; focal adhesion kinase; prognosis

Publ.-Id: 27955

Tuning the conductance of a molecular wire by the interplay of donor and acceptor units

Skidin, D.; Erdmann, T.; Nikipar, S.; Eisenhut, F.; Krüger, J.; Günther, F.; Gemming, S.; Kiriy, A.; Voit, B.; Ryndyk, D.; Joachim, C.; Moresco, F.; Cuniberti, G.

We investigate the conductance of optimized donor-acceptor-donor molecular wires obtained by on-surface synthesis on the Au(111) surface. A careful balance between acceptors and donors is achieved using a diketopyrrolopyrrole acceptor and two thiophene donors per unit along the wire. Scanning tunneling microscopy imaging, spectroscopy, and conductance measurements done by pulling a single molecular wire at one end are presented. We show that the conductance of the obtained wires is among the highest reported so far in a tunneling transport regime, with an inverse decay length of 0.17 Å-1. Using complex band structure calculations, different donor and acceptor groups are discussed, showing how a balanced combination of donor and acceptor units along the wire can further minimize the decay of the tunneling current with length.

Keywords: molecular electronics; density-functional; conductance; donor-acceptor polymer; DA polymer; STM; band structure; molecular wire


Publ.-Id: 27954

A spectroscopic investigation of Eu3+ incorporation in LnPO4 (Ln = Tb, Gd1–xLux, x = 0.3, 0.5, 0.7, 1) ceramics

Lösch, H.; Hirsch, A.; Holthausen, J.; Peters, L.; Xiao, B.; Neumeier, S.; Schmidt, M.; Huittinen, N.

We have investigated the incorporation of the luminescent Eu3+ cation in different LnPO4 (Ln = Tb, Gd1–xLux, x = 0.3, 0.5, 0.7, 1) host phases. All samples have been analyzed with powder X−ray diffraction (PXRD,) Raman spectroscopy, and time–resolved laser–induced luminescence spectroscopy (TRLFS) directly after synthesis and after an aging time of one year at ambient conditions. The PXRD investigations demonstrate the formation of a TbPO4 phase in an uncommon anhydrite–like crystal structure evoked by a pressure–induced preparation step (grinding). In the Gd1–xLuxPO4 solid solution series, several different crystal structures could be observed depending on the composition. The TRLFS emission spectra of LuPO4, Gd0.3Lu0.7PO4, and Gd0.5Lu0.5PO4 indicated Eu3+–incorporation within a xenotime–type crystal structure. TRLFS and PXRD investigations of the Gd0.7Lu0.3PO4 composition showed the presence of anhydrite, xenotime, and monazite phases, implying that xenotime no longer is the favored crystal structure due to the predominance of the substantially larger Gd3+–cation in this solid phase. Eu3+–incorporation could be seen to occur predominantly in the anhydrite–like structure with smaller contributions of Eu3+ incorporated in monazite and xenotime. The electronic levels of the Eu3+–dopant in Gd0.3Lu0.7PO4 and Gd0.5Lu0.5PO4 xenotime hosts were strongly coupled to external lattice vibrations, giving rise to high–energy peaks in the obtained excitation spectra. The coupling became stronger after aging to such an extent that direct excitation of Eu3+ in the xenotime structure was strongly suppressed. This phenomenon, however, was only visible for materials where Eu3+ was predominantly incorporated within the xenotime structure. Single crystals of Eu3+–doped LuPO4 showed no changes upon aging despite the presence of vibronically coupled excitation peaks in the excitation spectra measured directly after synthesis. Based on this observation, we propose a lattice relaxation process occurring in the powder samples during aging, resulting in Eu3+ migration within the crystal structure and Eu3+ accumulation at grain boundaries or xenotime surface sites.

Keywords: xenotime; PXRD; solid solutions; Eu3+ incorporation; TRLFS; grain boundary; ceramics

Publ.-Id: 27952

Optical Control of Plasmonic Hot Carriers in Graphene

Jadidi, M. M.; Daniels, K. M.; Myers-Ward, R. L.; Gaskill, D. K.; König-Otto, L. C.; Winnerl, S.; Sushkov, A. B.; Drew, H. D.; Murphy, T. E.; Mittendorff, M.

Plasmons in subwavelength-structured graphene surfaces exhibit strong light–matter interaction and prominent resonance effects in the terahertz/mid-IR frequency range. Due to its exceptionally small electronic specific heat, graphene shows strong photoinduced hot electron effects that significantly alter the plasmon response. This can enable fast control of plasmon resonance through transient heating of carriers. We employ nonlinear pump–probe measurements on subwavelength graphene ribbons to explore the effect of photoinduced hot carriers on graphene plasmons. Measurements taken above and below the plasmon resonance frequency clearly demonstrate an optically induced red-shift of the plasmon resonance, which is a signature of hot carriers in the graphene. The observed photoinduced change in plasmon resonance exhibits very strong (of order 10%) and fast response times (few picoseconds), which are governed by the cooling rate of hot electrons. The results presented here contribute to the understanding of plasmonic hot carriers in graphene and can find applications in fast terahertz modulation and switching.

Keywords: graphene; nonlinear; plasmons; pump−probe; terahertz


Publ.-Id: 27951

Comparative study of equivalent circuit models for photoconductive antennas

Castañeda-Uribe, O. A.; Criollo, C. A.; Winnerl, S.; Helm, M.; Avila, A.

Comparison of equivalent circuit models (ECM) for photoconductive antennas (PCA) represents a challenge due to the multiphysics phenomena involved during PCA operation and the absence of a standardized validation methodology. In this work, currently reported ECMs are compared using a unique set of simulation parameters and validation indicators (THz waveform, optical power saturation and ECM voltages consistency). The ECM simulations are contrasted with measured THz pulses of an H-shaped 20μm gap PCA at different optical powers (20mW to 220mW). In addition, an alternative two-element ECM that accounts for both space-charge and radiation screening effects is presented and validated using the proposed methodology. The model shows an accurately reproduced THz pulse using a reduced number of circuital elements, which represents an advantage for PCA modeling.

Keywords: THz emitters; photoconductive emitter; equivalent circuit model

Publ.-Id: 27950

Broadband Terahertz Detection With Zero-Bias Field-Effect Transistors Between 100 GHz and 11.8 THz With a Noise Equivalent Power of 250 pW/√Hz at 0.6 THz

Regensburger, S.; Mukherjee, A. K.; Schönhuber, S.; Kainz, M. A.; Winnerl, S.; Klopf, J. M.; Lu, H.; Gossard, A. C.; Unterrainer, K.; Preu, S.

We demonstrate UV contact lithographically fabricated III–V field-effect transistors (FETs) examined over a bandwidth of 100 GHz–11.8 THz. The zero-bias device reaches a noise equivalent power as low as 250 pW/√Hz at 0.6 THz, which then increases as f^4 at higher frequencies. The responsivity is modeled by a simple equivalent circuit, showing good agreement over the frequency range of two decades. The FETs have been characterized using a photomixer, a quantum cascade laser, and a free-electron laser, proving the versatility and large applicability of the detection concept.

Keywords: THz detection; broadband detection; field-effect transistor


Publ.-Id: 27949

openPMD Example Data Sets from PIConGPU 0.2.0

Hübl, A.

Quite outdated data but used in openPMD-api unit tests.

HDF5 data contains particle patches, ADIOS1 data does not. Uploading it here for reference, as a download point and for test reproducibility.

Keywords: openPMD; example data

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2018-09-19
    DOI: 10.14278/rodare.56
    License: CC-BY-4.0


Publ.-Id: 27948

Evidence for Crystalline Structure in Dynamically-Compressed Polyethylene up to 200 GPa

Hartley, N. J.; Brown, S.; Cowan, T.; Cunningham, E.; Döppner, T.; Falcone, R. W.; Fletcher, L. B.; Frydrych, S.; Galtier, E.; Gamboa, E. J.; Laso Garcia, A.; Gericke, D. O.; Glenzer, S. H.; Granados, E.; Heimann, P. A.; Lee, H. J.; Macdonald, M. J.; Mackinnon, A. J.; Mcbride, E. E.; Nam, I.; Neumayer, P.; Pak, A.; Pelka, A.; Prencipe, I.; Ravasio, A.; Rödel, M.; Rohatsch, K.; Saunders, A. M.; Schölmerich, M.; Schörner, M.; Schuster, A. K.; Sun, P.; van Driel, T.; Vorberger, J.; Kraus, D.

We have investigated the high-pressure behavior of polyethylene by probing dynamically shock-compressed samples with x-ray diffraction. At high pressures, comparable to those present inside icy giant planets (Uranus, Neptune), shock-compressed polyethylene (CH2) retains a crystal structure, from which we infer the presence of significant covalent bonding. This finding appears to contrast with recent results from shock-compressed polystyrene (CH), which demonstrated demixing and recrystallization into a diamond lattice, implying the breaking of the original chemical bonds. As such chemical processes have significant implication for the structure and energy balance within ice giants, our results highlight the need for a deeper understanding of the chemistry of high pressure hydrocarbons, and underline the importance of better constraining the temperature profiles inside such planets.

Publ.-Id: 27946

Accelerator mass spectrometry measurement of the reaction ³⁵Cl(n,gamma)³⁶Cl at keV energies

Pavetich, S.; Wallner, A.; Martschini, M.; Akhmadaliev, S.; Dillmann, I.; Fifield, K.; Halfon, S.; Heftrich, T.; KÄppeler, F.; Lederer-Woods, C.; Merchel, S.; Paul, M.; Reifarth, R.; Rugel, G.; Steier, P.; Tessler, M.; Tims, S.; Weigand, M.; Weissman, L.

The nuclide ³⁵Cl can act as a minor "neutron poison" in the stellar slow neutron capture process. Neutron activation combined with accelerator mass spectrometry (AMS) was applied to measure the (n,gamma) cross section of ³⁵Cl for neutron spectra simulating Maxwell-Boltzmann distributions of kT ~30 keV and 40 keV, respectively. The neutron activations were performed at the Karlsruhe Van de Graaff accelerator and at the superconducting linear accelerator of the Soreq Applied Research Accelerator Facility utilizing the ⁷L(p,n)⁷Be reaction. AMS measurements of the irradiated samples were performed at the 3 MV Vienna Environmental Research Accelerator, the 6 MV tandem accelerator at the Dresden AMS facility, and the 14 UD tandem accelerator of the Australian National University in Canberra. Our method is independent of previous measurements. For an energy of kT=30 keV, we report a Maxwellian averaged cross sections of 8.33(32) mb. Using this new value in stellar isotopic abundance calculations, minor changes for the abundances of ³⁵Cl, ³⁶Cl and ³⁶S are derived.

Keywords: s-process; Maxwellian averaged cross section; ³⁵Cl; accelerator mass spectrometry; neutron activation

Publ.-Id: 27945

Beitrag zur Erkundung und metallogenetischen Charakteristik der Li-Sn-W-Greisenlagerstätte Zinnwald, Osterzgebirge, Deutschland

Neßler, J.; Seifert, T.; Gutzmer, J.; Müller, A.

Die Lagerstätte Zinnwald gehört zu den bedeutendsten Greisenlagerstätten der zentraleuroäischen Varisziden, die nach einem über mehrere Jahrhunderte währenden historischen Bergbau auf Sn- und W-Erze erneute rohstoffkundliche Bedeutung hinsichtlich ihrer Li-Ressourcen erlangt hat. Im Zuge einer internationalen Bewertungskriterien entsprechenden Explorationskampagne wurde die Lagerstätte zwischen 2011 und 2014 auf Li-Sn- und W- führende Greisenerze erkundet, welche im obersten Teil der grenzüberschreitenden Granitintrusion von Zinnwald entwickelt sind.
Auf Grundlage historischer Erkundungsergebnisse und insgesamt neun im Projektzeitraum abgeteufter Kernbohrungen (Gesamtlänge ca. 2480 m) war es möglich neben der Abschätzung der Li-Ressourcen generelle Charakteristika zur Ausbildung der Greisenmineralisation im deutschen Lagerstättenteil abzuleiten. Ein wesentliches Ergebnis liegt in der Bestätigung der strukturell kontrollierten Lagerstättenarchitektur vor, welche eine flach fallende und generell dem Granitkontakt folgende Lagerung der Greisenerzkörper im Endokontakt entlang subhorizontaler Abkühlungsklüfte vorsieht. Während der Hauptanteil der Li-Mineralisation im zentralen Scheitelbereich der albitgranitischen Intrusion ausgebildet ist, konnte mit Hilfe der aktuellen Bohrungen der Nachweis einer weiteren Hauptvererzungszone mit bis zu 50 m mächtigen Greisenkörpern entlang der Ostflanke erbracht werden. Ein weiteres Ergebnis von außerordentlicher metallogenetischer und möglicherweise ökonomischer Bedeutung stellt die Entdeckung einer kontinuierlich mineralisierten Zone disseminierter Sn-W-Vererzung von schwach vergreistem Albitgranit im Liegenden der Greisenerze dar. Mit einer scheinbaren Mächtigkeit von 20 m lässt sich diese im Liegenden der Greisenkörper über eine streichende Erstreckung von mindestens 700 m nachweisen.
Die chemische Zusammensetzung der Gesteine und Erze im Endo- bzw. Exokontakt wurde anhand von über 1300 Multielementanalysen von Bohrkern- und untertägigen Schlitzproben bestimmt. Der geochemisch bereits stark spezialisierte Charakter der Granitintrusion von Zinnwald hat im Zuge der metasomatischen Vergreisungsprozesse eine weitere Vervielfachung der Konzentrationswerte, insbesondere für F, Fe, Li, Rb, Cs, Zn sowie Sn, W und Mo, erfahren. Während die Erzelemente Li und W keine systematischen Veränderungen über den Teufenbereich der Vergreisung zeigen, deuten die Sn-Konzentrationen in Greisen und vergreisten Albitgranit auf eine deutliche Abnahme mit zunehmender Entfernung zum Endokontakt.
Das Haupterzmineral der Li-Mineralisation stellt das trioktaedrische Schichtsilikat Zinnwaldit dar, welches mit durchschnittlich 25 Vol. % am Modalbestand typischer Greisen beteiligt ist. Neben Li Gehalten zwischen 1,1 und 2,3 Gew. % deuten umfangreiche Untersuchungen mittels EPMA und LA-ICP-MS auf stark variierende, teufenabhängige und für einzelne Gesteinsproben individuelle Ti Sn-Verhältnisse hin. Die Ergebnisse demonstrieren eine gute Übereinstimmung und Fortsetzung geochemischer Trends mit Literaturdaten aus tieferen Bereichen des Granitstocks von Zinnwald/Cínovec und können als Hinweis auf die Spurenelementänderung mit der Transformation von Protolithionit zu Zinnwaldit sowie auf eine erneute Anreicherung von Sn im Kristallgitter der Zinnwalditkörner im obersten, Hauptverer-zungsbereich angesehen werden.
Im Rahmen der vorgestellten Arbeit wurden Zinnwalditseparate aus Greisenerzen, Greisengängen und unvererztem Nebengestein mittels 40Ar/39Ar-Altersbestimmung datiert. Alle Proben deuten im Ergebnis auf ein einheitliches Alter von 312,8±1,8 Ma, welches als Alter der Vergreisung und der damit einhergehenden Bildung von oder Verdrängung durch Zinnwaldit interpretiert wird.
Die Ergebnisse dieser Arbeit tragen damit zu einem bedeutenden Kenntniszuwachs des Lagerstättenpotentials sowie zum besseren Verständnis von Architektur, Zusammensetzung und zeitlicher Einstufung der Gesteine und Erzmineralisation bei. Die genetischen Implikationen erweitern die generellen Vorstellungen der lagerstättenbildenden Prozesse und können somit hilfreich für weitere Explorationsarbeiten innerhalb der Lagerstätte sowie in anderen granitgebundenen Greisenlagerstätten sein. Weiterhin deuten die Ergebnisse auf einen der metasomatischen Bildung von Li-Glimmergreisen stofflich und evtl. auch zeitlich abweichenden Sn-W-Mineralisationsprozess hin.
Während die Rohstofferkundung die Bedeutung der Lagerstätte Zinnwald als eine der größten Li-Lagerstätten Europas

Keywords: Zinnwald; Erzgebirge; Lithium; Zinn; Metallogenese; Greisen

  • Book (Authorship)
    Freiberg: TU Bergakademie Freiberg, 2017

Publ.-Id: 27944

Oxidative leaching of a sulfidic flue dust of former copper shale processing with focus on rhenium

Helbig, T.; Gilbricht, S.; Lehmann, F.; Daus, B.; Kelly, N.; Haseneder, R.; Scharf, C.

The investigation aims at a hydrometallurgical processing approach for an environmentally hazardous material called “Theisenschlamm”, which is a flue dust of former copper shale processing in Germany. Besides eliminating the negative environmental impact, processing of this material would also be a contribution to a circular economy, since it contains about 16 wt.-% zinc, 14 wt.-% lead, minor amounts of copper and tin, as well as valuable elements of strategic economic importance, such as rhenium, molybdenum and germanium. The mainly sulfidic matrix of the Theisenschlamm was characterised using scanning electron microscopy in combination with QEMSCAN software. Leaching of Theisenschlamm in acidic and alkaline media, as well as the effect of oxidising agents, was studied in order to extract zinc, copper, rhenium, germanium and molybdenum. In both sulphuric acid and sodium hydroxide solutions, the addition of oxidising agents (hydrogen peroxide and ozone) improved metal extraction efficiencies significantly. The leaching system sulphuric acid/hydrogen peroxide was investigated in more detail, with focus on the optimisation of rhenium extraction and its effect on the extraction efficiencies of the other target elements. Response surface methodology was applied with respect to H₂SO₄ concentration (0.1–1.2 mol/L), H₂O₂ concentration (0.1–2.8 mol/L) and solid:liquid ratio (40–150 g/L). This study shows that oxidative leaching enables the extraction of zinc, copper, rhenium, germanium and molybdenum from this sulfidic material. In terms of rhenium extraction, a low acid concentration is favourable; however, lowering the acid concentration results in a reduced yield of other target elements (e.g. molybdenum).

Keywords: Theisenschlamm; Copper shale; Rhenium; Oxidative leaching; QEMSCAN

Publ.-Id: 27943

A realistic approach for the assessment of the consequences of heterogeneous boron dilution events in pressurized water reactors

Kliem, S.; Grahn, A.; Bilodid, Y.; Höhne, T.

In order to compensate the excess reactivity over the fuel cycle in pressurized water reactors, boric acid is added to the reactor coolant. The formation and the subse-quent transportation towards the core of coolant with reduced boron concentration can lead to a positive reactivity insertion into the reactor core. In this paper a new approach of dealing with such heterogeneous boron dilution scenarios is presented. This approach is based on the use of computational fluid dynamics methods for the whole reactor pressure vessel with direct coupling of a neutron-kinetic model of the reactor core.
The application of this approach is demonstrated on a main coolant pump start scenario for hot-shutdown conditions using the coupled DYN3D/ANSYS CFX code.

Keywords: Boron dilution; DYN3D; CFD; neutron kinetics/thermal hydraulics coupling; PWR


Publ.-Id: 27942

Analysis of moulded wood tube structure using gamma-ray computed tomography

Bieberle, A.; Engmann, C.; Hartig, J.; Haller, P.
ContactPerson: Bieberle, André; ContactPerson: Haller, Peer

For the investigation of compressive load moulded wood tube gamma-ray CT has been applied at a 3 m long wood tube at different cross-sectional sections. CT data is normalized to the density of tap water with app. 22 °C temperature.

Keywords: moulded wood tube; gamma-ray computed tomography

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2018-09-18
    DOI: 10.14278/rodare.54


Publ.-Id: 27941

Experimental and Theoretical Study of Curvature Effects in Parabolic Nanostripes

Volkov, O. M.; Kronast, F.; Mönch, I.; Mawass, M.-A.; Kákay, A.; Fassbender, J.; Makarov, D.

Curvature effects in magnetism offer appealing possibilities to obtain new magnetic textures at the nanoscale due to the interplay between exchange and magnetostatic interactions. Experimentally and theoretically, curvature driven changes of static magnetic properties in parabolic nanostripes have been addressed here. The shape of a parabolic stripe is tuned to cover broad range of widths and curvatures allowing to construct a phase diagram of magnetic equilibrium states. For this, joint experimental, i.e., soft X-ray imaging, and theoretical studies are carried out. Analytical calculations in the framework, when non-local magnetostatic effects are neglected, coincide with the experimental and simulation results in a broad range of parameters. The results give confidence in the applicability of the existing theoretical framework for further analytical considerations of equilibrium magnetization states of curvilinear nanomagnets.

Publ.-Id: 27940

Geometry-induced motion of magnetic domain walls in curved nanostripes

Yershov, K. V.; Kravchuk, V. P.; Sheka, D. D.; Pylypovskyi, O. V.; Makarov, D.; Gaididei, Y.

Dynamics of topological magnetic textures are typically induced externally by, e.g., magnetic fields or spin/charge currents. Here, we demonstrate the effect of the internal-to-the-system geometry-induced motion of a domain wall in a curved nanostripe. Being driven by a gradient of the curvature of a stripe with biaxial anisotropy, transversal domain walls acquire remarkably high velocities of up to 100m/s and do not exhibit any Walker-type speed limit. We pinpoint that the inhomogeneous distribution of the curvature-induced Dzyaloshinskii-Moriya interaction is a driving force for the motion of a domain wall. Although we showcase our approach on the specific Euler spiral geometry, the approach is general and can be applied to a wide class of geometries.


Publ.-Id: 27939

Experimental study of the mold flow induced by a swirling flow nozzle and electromagnetic stirring for continuous casting of round blooms

Schurmann, D.; Willers, B.; Hackl, G.; Tang, Y.; Eckert, S.

This study focuses on an experimental investigation of the fluid flow in round bloom continuous casting using a 1:3 model of the industrial casting process. A swirling flow nozzle, represented by the particular design of the RHI Magnesita GYRONOZZLE, is used to produce a swirling motion in the cylindrical mold. The test section is integrated in the Mini-LIMMCAST facility at HZDR, which is operated at room temperature using the ternary alloy GaInSn. Systematic measurements of horizontal and vertical velocity profiles are performed by means of the Ultrasound Doppler Velocimetry (UDV). The second part of the study focuses on the interaction between the flow driven by the GYRONOZZLE and concurrent electromagnetic stirring in the mold (M-EMS) by applying rotating magnetic fields (RMF) at different magnetic flux densities. The effect of the GYRONOZZLE on the flow pattern inside the mold is examined with and without superimposed RMF and compared to those of a standard single-port nozzle. The measurements reveal that the GYRONOZZLE induces a swirling flow in the whole mold. It is further shown that the influence of a simultaneously applied RMF is mainly restricted to the lower part of the mold since the transport of angular momentum to the top is suppressed by the jets pouring out from the GYRONOZZLE.

Keywords: Continuous Casting; Round Bloom Casting; Swirling Flow Nozzle; Liquid Metal Model Experiments; Flow Measurements; Ultrasound Doppler Velocimetry (UDV)


Publ.-Id: 27938

Reversibly assembled electroconductive hydrogel via host-guest interaction for 3D cell culture

Xu, Y.; Cui, M.; Patsis, P.; Günther, M.; Yang, X.; Eckert, K.; Zhang, Y.

Study of cells responding to an electroconductive environment is impeded by the lack of method, which would allow
the encapsulation of cells in an ECM-like 3D electroactive matrix, and more challengingly, permit a simple mechanism to release cells for further characterization. Herein we report a polysaccharide-based conductive hydrogel system formed via cyclodextrinadamantane host-guest interaction. Oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of adamantyl modified sulfated alginate (S-Alg-Ad) results in bio-electroconductive polymer PEDOT:S-Alg-Ad, which can form hydrogel with poly-β-Cyclodextrin (pβ-CD). The PEDOT:S-Alg-Ad/ pβ-CD hydrogels can be tuned on aspects of mechanical and electrical properties, exhibit self-healing feature and are injectable. Electron microscopy suggested that the difference in stiffness and conductivity is associated with the nacre-like layered nano-structures when different sizes of PEDOT:S-Alg-Ad nanoparticles were used. Myoblasts C2C12 cells were encapsulated in the conductive hydrogel and exhibited proliferation rate comparable to that in non-conductive S-Alg-Ad/pβ-CD hydrogel. The cells could be released from the hydrogels by adding β-CD monomer, and the upregulations of most myogenic marker genes under differentiation condition were more remarkable than the non-conductive counterpart. Astonishingly, the conductive hydrogel can dramatically promote myotube-like structure formation, while the myocytes grow into large clusters in the non-electroconductive hydrogel. The ability to embed and release cells in an electroconductive environment will open new doors for cell culture and tissue engineering.

Keywords: host-guest; self-assembling; PEDOT; electroconductive hydrogel; 3D cell culture

Publ.-Id: 27937

Surface Instability of Paramagnetic Liquid in Non-uniform Magnetic Field

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

The manipulation of magnetic fluids by external magnetic field is contactless and free of Joule heating. The paramagnetic liquid offers possibly of manipulation and has a potential application in rare earth element separation. Yet, unlike super-paramagnetic liquid, e.g. ferrofluid, such dynamics is lack of investigation. To observe the combined effect of gravity and magnetic field on paramagnetic solution, the permanent magnet was moved vertically above the free surface of DyCl3 and MnSO4 solution. The change of interface was followed optically by shadowgraph. The focus of the work is the interfacial height difference. Moreover, the morphology of the free interface was observed. The objective one is investigated by changing the concentrations as well as the speed of applying and removing of the magnet. The speed of the moving magnet falls into two categories. One relates to quasi-static magnetization and demagnetization and the second represents jump-like magnetization and demagnetization, i.e. 0.5 mm/s and 20 mm/s respectively. It was found, that the level of liquid is oscillating with specific frequency defined by concentration of solution and is independent of the magnet velocity.

Keywords: paramagnetic liquid; surface instability; shadowgraph; non-uniform magnetic field

  • Lecture (Conference)
    9th International Astronautical Congress (IAC), 01.-05.10.2018, Bremen, Germany

Publ.-Id: 27936

Study of the Marangoni effect on the gas evolution during electrolysis

Hossain, S.; Mutschke, G.; Eckert, K.; Massing, J.; Yang, X.; Baczyzmalski, D.; Cierpka, C.

Electrolytic gas evolution is a fundamental phenomenon occurring in a large number of industrial applications where gas bubbles grow at electrodes from a supersaturated solution. Since dissolved gases or ionic species can change the surface tension, a gradient may exist along the interface between the gas bubble and the electrolyte. Surface tension gradients may also arise from temperature gradients generated from Ohmic heating by the Faradaic current. The resulting shear stress can drive convection at the interface (Marangoni effect) which may influence the mass transfer across the interface during growth and finally the departure of the gas bubble.
In this study, numerical simulations are performed on Marangoni convection around a hydrogen gas bubble grown electrochemically at a microelectrode in an acidic electrolyte. The results are compared with recent experimental results on the near-bubble convection obtained by a Particle Tracking Velocimetry (PTV) technique and on corresponding temperature measurements. A clear evidence for the Marangoni effect is found [1], and the ratio of thermal and solutal Marangoni effects is discussed.

[1] X. Yang et al., Phys. Chem. Chem. Phys., accepted (2018).

Keywords: electrolysis; gas evolution; Marangoni effect; convection; numerical simulation

  • Lecture (Conference)
    12. European Fluid Mechanics Conference, 09.-13.09.2018, Wien, Österreich

Publ.-Id: 27935

Convection and mass transfer near a hydrogen bubble evolving during water electrolysis in magnetic fields

Mutschke, G.; Yang, X.; Eckert, K.; Uhlemann, M.; Baczyzmalski, D.; Cierpka, C.

Hydrogen produced from wind or solar power could be used easily for storing energy also at large scale, thus allowing to bridge the gap between supply and demand of renewable energy with respect to time and place. When splitting water by electrolysis, a deeper look at local phenomena near single bubbles at the electrode might be helpful to improve our understanding of this process. In the recent literature, magnetic fields are discussed with respect to the bubble departure, thereby possibly influencing the efficiency of the process [1-5].
The contribution will present numerical simulations resolving in detail local phenomena near a single hydrogen bubble evolving at a small circular cathode during the electrolysis of water. The results are compared with experimental data of hydrogen evolution at a platinum micro-electrode. Hereby, the influence of the Lorentz force caused by vertical and horizontal magnetic fields will be discussed. The results presented will provide insight into electrolyte convection, species concentration, mass transfer and on the bubble departure [6-8].

Keywords: electrolysis; gas evolution; convection; mass transfer; magnetic field; Lorentz force; numerical simulation

  • Lecture (Conference)
    12. European Fluid Mechanics Conference, 09.-13.09.2018, Wien, Österreich

Publ.-Id: 27934

SRF gun development at DESY

Vogel, E.; Sekutowicz, J.; Barbanotti, S.; Hartl, I.; Jensch, K.; Klinke, D.; Kostin, D.; Moeller, W.-D.; Schmoekel, M.; Sievers, S.; Steinhau-Kuehl, N.; Sulimov, A.; Thie, J.-H.; van der Horst, B.; Weise, H.; Winkelmann, L.; Smedley, J.; Teichert, J.; Wiencek, M.; Lorkiewicz, J. A.; Nietubyc, R.

A future upgrade of the European XFEL (E-XFEL) foresees an additional CW operation mode, which will increase the flexibility in the photon beam time structure [1, 2, 3]. One of the challenges of this operational mode is the need for a CW operating photo injector. We believe that using an SRF gun is the preferred approach as the beam parameters of normal conducting pulsed guns can be potentially met by SRF guns operating CW. For more than a decade DESY, in collaboration with TJNAF, NCBJ, BNL, HZB and HZDR, has performed R&D to develop an all superconducting RF gun with a lead cathode. In the frame of E-XFEL CW upgrade feasibility studies, the SRF-gun R&D program gained more attention and support. Within the next few years we would like to demonstrate the performance of the all superconducting injector required for the E-XFEL upgrade. The selected approach offers advantages w.r.t. the cleanliness of the superconducting surface, but requires a complete disassembly of a cryostat and stripping the gun cavity in a clean room to exchange the cathode. Thus it is practical only when the life time of the cathode is at least several months. In this paper we present the actual status of the R&D program, next steps and the longer term plans.

Keywords: superconducting RF gun; photo injector; lead cathode; electron source

  • Poster
    29th Linear Accelerator Conference-LINAC18, 16.-21.09.2018, Beijing, China
  • Open Access Logo Contribution to proceedings
    29th Linear Accelerator Conference-LINAC18, 16.-21.09.2018, Beijing, China
    Proc. of 29th Linear Accelerator Conference-LINAC18, Genf: JACoW

Publ.-Id: 27933

Synthesis, 18F-labelling and radiopharmacological characterisation of the C-terminal 30mer of Clostridium perfringens enterotoxin as a potential claudin-targeting peptide

Löser, R.; Bader, M.; Kuchar, M.; Wodtke, R.; Lenk, J.; Wodtke, J.; Kuhne, K.; Bergmann, R.; Haase-Kohn, C.; Urbanová, M.; Steinbach, J.; Pietzsch, J.

The cell surface receptor claudin-4 (Cld-4) is upregulated in various tumours and represents an important emerging target for both diagnosis and treatment of solid tumors of epithelial origin. The C-terminal fragment of the Clostridium perfringens enterotoxin cCPE290-319 appears as a suitable ligand for targeting Cld-4. The synthesis of this 30mer peptide was attempted via several approaches, which has revealed sequential SPPS using three pseudoproline-dipeptide building blocks to be the most efficient one. Labelling with fluorine-18 was achieved on solid phase using N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB) and 4-[18F]fluorobenzoyl chloride as 18F-acylating agents, which was most advantageous when [18F]SFB was reacted with the resin-bound 30mer containing an N-terminal 6-aminohexanoic spacer. Binding to Cld-4 was demonstrated via surface plasmon resonance using a protein construct containing both extracellular loops of Cld-4. In addition, cell binding experiments were performed for 18F-labelled cCPE290-319 with the Cld-4 expressing tumour cell lines HT-29 and A431 that were complemented by fluorescence microscopy studies using the corresponding fluorescein isothiocyanate-conjugated peptide. The 30mer peptide proved to be sufficiently stable in blood plasma. Studying the in vivo behavior of 18F-labelled cCPE290-319 in healthy mice and rats by dynamic PET imaging and radiometabolite analyses has revealed that the peptide is subject to substantial liver uptake and rapid metabolic degradation in vivo, which limits its suitability as imaging probe for tumour-associated Cld-4.

Keywords: radiolabelled peptides; 18F-fluorobenzoylation; difficult peptide sequences; claudin family of tight junction proteins; molecular imaging; small animal positron emission tomography


Publ.-Id: 27932

Hydrometallurgy @ HIF

Gutzmer, J.

Hydrometallurgical research of HZDR will be presented in this contribution. .An overview will be provided on relevant hydrometallurgical research carried out in Freiberg and in Dresden. The progress of collaborative research projects will be documented and preliminary results presented. A particular focus will be set on the development of pilot plant-scale research facilities and the opportunities this offers for future research.

Keywords: Hydrometallurgy; HZDR

  • Invited lecture (Conferences)
    BASF Innovation Day, 13.-14.09.2018, Ludwigshafen, Germany

Publ.-Id: 27931

Fourier Analysis of Cerebral Metabolism of Glucose Revealed Gender Differences in Ventral and Dorsal Streams for Colour Processing in Mice

Njemanze, P.; Kranz, M.; Brust, P.

Fourier analysis of regional cerebral metabolic rate of glucose (CMRglc) as estimated by measurement of standardized uptake values (SUVs) of [18F]fluorodeoxyglucose ([18F]FDG) using functional positron emission tomography magnetic resonance imaging (fPET/MRI) revealed activation patterns during white light and colour stimulation in male and female mice, respectively. Spectral density curves of the cortical and subcortical peaks demonstrated wavelength-differencing for luminance and chromatic opponency in the ventral stream in male mice, but frequency-differencing in the dorsal stream in female mice. Male mice demonstrated subcortico-cortical bottom-up feed-forward system for light and colour processing, while in female mice there was a cortico-subcortical top-bottom feed-back system.
Fourier time series analysis was helpful to improve both spatial and temporal resolution of PET/MRI for study of colour processing in the visual system. It demonstrated computation of colour processing as conscious experience, and has a wide range of applications including in artificial intelligence and quantum mechanics.

Keywords: chromatic opponency; sex differences; light wave; light particle; blood flow; frequency; resonance

  • Contribution to proceedings
    ITISE 2018 (International conference on Time Series and Forecasting), 19.-21.09.2018, Granada, Espana
    Proceedings of the International conference on Time Series and Forecasting, Granada: Godel Impresiones Digitales S.L., 978-84-17293-57-4

Publ.-Id: 27930

Simulation based LCA – Digitalizing the Circular Economy - Its simulation with two cases: eWaste & batteries/Zn fuming

Reuter, M. A.

Circular Economy (CE)
-The origins
Circular Economy Engineering (CEE)
Metallurgical Internet-of-Things (m-IoT)
-Comprehensive flowsheets that integrate product design with physical separation and process metallurgy
Informing Resource Efficiency (iRE)
-Case 1: Fairphone
-Case 2: Plasma furnace for battery smelting & fuming
Additional Sheets
-Case 3: Recycling of LED lamps / Literature / More detailed sheets

Keywords: Circular Economy; Sustainability; Circular Economy Engineering; thermoeconomics; recycling; Metallurgical Internet of Things; Metal Wheel; Digitalizing

  • Lecture (others)
    HSC 9 Life Cycle Assessment for Process Industry // Training Courses, 03.-05.06.2018, Pori, Finnland

Publ.-Id: 27929

Experimental study of liquid velocity profiles in large-scale bubble columns with particle tracking velocimetry

Besagni, G.; Inzoli, F.; Ziegenhein, T.; Lucas, D.

A complete knowledge of bubble column fluid dynamics relies on understanding both the “global-scale” and the “local-scale” phenomena and coupling between the phases. Unfortunately, most of the previous literature focused on the “global-scale” fluid dynamics, whereas a limited attention was devoted to the “local-scale” fluid dynamics. In this study, we contribute to the present-day discussion through an experimental study concerning the local liquid velocity field in the pseudo-homogeneous flow regime. The experimental study, based on a particle-identification and particle-tracking algorithm, was conducted in a large-diameter and large-scale air-water bubble column (with a height of 5.3 m and inner diameter of 0.24 m) operated in the counter-current mode. We considered gas superficial velocities in the range of 0.37–1.88 cm/s and liquid superficial velocities up to −9 cm/s. The time-averaged and the transient liquid velocity field were obtained and critically discussed for five superficial gas velocities and four superficial liquid velocities at two measuring heights. Subsequently, the local locally resolved information concerning the liquid velocity were coupled with the previously measured bubble size distributions and local void fractions, to provide a complete description of the “local-scale” fluid dynamics. In addition, these data would help in the validation of numerical codes to predict industrial-scale relevant conditions.

Keywords: bubbly column; pilot scale; experiment

  • Contribution to proceedings
    36th UIT Heat Transfer Conference, 25.-27.06.2018, Catania, Italy
  • Lecture (Conference)
    36th UIT Heat Transfer Conference, 25.-27.06.2018, Catania, Italy
  • Open Access Logo Journal of Physics: Conference Series 1224(2019), 012036
    DOI: 10.1088/1742-6596/1224/1/012036

Publ.-Id: 27928

Multi-fluid models for gas-liquid flows

Lucas, D.; Krepper, E.; Liao, Y.; Höhne, T.; Rzehak, R.; Schlegel, F.; Ziegenhein, T.

The two- or multi-fluid approach is frequently used for NRS-related simulations of gas-liquid flows. To enable reliable predictions the closure models have to reflect the involved local physical phenomena at the non-resolved scale properly. To consolidate the CFD-modelling in the frame of the multi-fluid approach the so-called baseline model strategy was recently proposed (Lucas et al., 2016). The paper discusses a long-term strategy for the baseline model development and ways to obtain or improve closure models. Guidelines for the model development are given by listing requirements for appropriate closure models as well as frequently made mistakes. This is illustrated by examples for recent developments done for HZDR baseline models for poly-disperse bubbly and segregated flows. Beside an update on recent developments ongoing and planned activities are discussed. Both models are united in the GENTOP-concept which allows simulating flow pattern transitions. Finally, perspectives for the use of OpenFOAM for NRS are discussed.

Keywords: CFD; multiphase; closure model; validation

  • Contribution to proceedings
    OECD/NEA&IAEA CFD4NRS-7 Workshop Application of CFD/CMFD Codes to Nuclear Reactor Safety and Design and their Experimental Validation, 04.-06.09.2018, Shanghai, China
  • Lecture (Conference)
    OECD/NEA&IAEA CFD4NRS-7 Workshop Application of CFD/CMFD Codes to Nuclear Reactor Safety and Design and their Experimental Validation, 04.-06.09.2018, Shanghai, China

Publ.-Id: 27927

High peak currents from a beam loaded nanocoulomb-class laser wakefield accelerator

Couperus, J. P.; Köhler, A.; Zarini, O.; Pausch, R.; Kurz, T.; Krämer, J. M.; Schöbel, S.; Laberge, M.; Hannasch, A.; Zgadzaj, R.; Heinemann, T.; Martinez De La Ossa, A.; Debus, A.; Bussmann, M.; Downer, M.; Schramm, U.; Irman, A.

Laser wakefield accelerators have the capability to produce few-femtosecond, high charge and high peak current beams in the GeV energy range within only a few centimeters of acceleration length. The unique beam properties from these novel concept accelerators can be employed to explore new concepts such as beam driven plasma acceleration or driving superradiant light sources, which require peak currents beyond those found in current conventional accelerators.
Here, we report on robust generation of high quality electron beams at unprecedented high peak currents. The self-truncated ionization injection scheme is employed, enabling a precise control over the amount of injected electrons with charges up to 0.5 nC (FWHM) at a quasi-monoenergetic peak. Minimization of energy spread is reached by optimizing the beam loading condition1,2. An ultrafast single-shot electron beam diagnostic based on Coherent Optical Transition Radiation reveals ~10 femtosecond bunch lengths yielding peak currents of over 10 kA. Such peak currents are one to two orders of magnitude larger than those found in conventional RF accelerators. Control of the energy spread of LWFA beams with the beam loading condition together with the scaling to high peak currents paves the road for driving superradiant lights sources and enables the first proof-of-principle experiment of a hybrid laser- to beam-driven plasma wakefield accelerator in an effort to further improve beam quality found in plasma accelerators.

1 J.P. Couperus et al., “Demonstration of a beam loaded nanocoulomb-class laser wakefield accelerator”, Nature Communication, 8, 487 (2017)
2 A. Irman et al., “Improved performance of laser wakefield acceleration by tailored self-truncation ionization injection”, Plasma Physics and Controlled Fusion, 60, 044015 (2018)

Keywords: Laser Wakefield Acceleration; LWFA; Beam loading; Electron acceleration

  • Lecture (Conference)
    Advanced Accelerators Concepts Workshop, 13.-17.08.2018, Breckenridge, Colorado, USA

Publ.-Id: 27926

Molecular imaging using the theranostic agent 197(m)Hg: phantom measurements and Monte Carlo simulations

Freudenberg, R.; Apolle, R.; Walther, M.; Hartmann, H.; Kotzerke, J.

Background: Radiomercury 197mHg and 197Hg, henceforth referred to as 197(m)Hg, is a promising theranostic radionuclide endowed with properties that allow diagnostic and therapeutic applications. The aim of this work was to investigate the capabilities of 197(m)Hg for nuclear medicine imaging. Therefore measurements were performed by using a Philips BrightView SPECT camera. Furthermore, Monte Carlo simulations using the GATE software were performed to theoretically explore the imaging contribution from the various gamma and X-ray emissions from 197(m)Hg for a commercial clinical camera with low-energy high-resolution (LEHR) and high-energy general-purpose (HEGP) collimators. We estimated the spatial resolution by using a four-quadrant bar phantom, and we evaluated the planar and tomographic images from an abdominal phantom containing three cylindrical sources of 197(m)Hg solution.
Results: A good accordance between measurements and simulations was found for planar and SPECT imaging. Simulations allowed the decomposition of the detected energy spectrum into photon origins. Measurements and simulations for the bar phantom revealed that for the LEHR collimator, the 6-mm pattern could be resolved, whereas for the HEGP collimator, the resolution is about 10 mm. Furthermore, we found that no significant image distortion results from high-energy photons when using the LEHR collimator.
Conclusions: We demonstrated the imaging capabilities of 197(m)Hg which is essential both for diagnostic applications and to determine the in vivo biodistribution for dose calculations in therapeutic applications.

Keywords: GATE; Gamma camera; 197(m)Hg; Monte Carlo simulation; Radiomercury


Publ.-Id: 27925

State of the Art Design for Recycling: Case Fairphone

Reuter, M. A.

  • Circular Economy (CE)
  • Circular Economy Engineering (CEE)
  • Metallurgical Internet-of-Things (m-loT)
  • informing Resource Efficieny (iRE) - Fairphone
  • Additional Sheets - Recycling of LED lamps/Literature/More detailed sheets

Keywords: Circular Economy; Circular Economy Engineering; Metallurgical Internet-of-Things; Resource Efficieny; Fairphone; Recycling

  • Invited lecture (Conferences)
    Recycling Metals from Industrial Waste - Anual Short Course / Workshop, 26.-29.06.2018, Golden Colorado, USA

Publ.-Id: 27924

Die Digitalisierung der Kreislaufwirtschaft - Wie recyclebar sind Smartphones?

Reuter, M. A.

Circular Economy (CE)
Circular Economy Engineering (CEE)
Metallurgical Internet-of-Things (m-IoT)
informing Resource Efficiency (iRE)

Keywords: Circular Economy; Circular Economy Engineering; Metallurgical Internet-of-Things; Resource Efficiency

  • Lecture (others)
    Intelligente Kreislaufwirtschaft - Aktuelle Aspekte zu Recycling, Aufbereitung und Fernerkundung / Lehrerfortbildung, 16.02.2018, Freiberg, Deutschland

Publ.-Id: 27923

Simulation based footprint of technology

Reuter, M. A.

Overview of Circular Economy in the Metallurgical Processing Industry
Introduction into HSC / into Simulation Based Footprinting / of Case: Processing of slag in a plasma furnace
Completion of Case
Environmental impact assessment using HSC Sim and GaBi

Keywords: Circular Economy; Resource Efficiency; Recycling; Sustainability; Circular Economy Engineering; Fairphone

  • Lecture (others)
    EIT KIC Workshop, 15.-17.05.2018, Freiberg, Deutschland

Publ.-Id: 27922

Utility of fiducial markers for target positioning in proton radiotherapy of oesophageal carcinoma

Apolle, R.; Brückner, S.; Frosch, S.; Rehm, M.; Thiele, J.; Valentini, C.; Lohaus, F.; Babatz, J.; Aust, D. E.; Hampe, J.; Troost, E. G. C.

Background and purpose
Oesophageal mobility relative to bony anatomy is a major source of geometrical uncertainty in proton radiotherapy of oesophageal carcinoma. To mitigate this uncertainty we investigated the use of implanted fiducial markers for direct target verification in terms of safety, visibility, and stability.
Materials and methods
A total of 19 helical gold markers were endoscopically implanted in ten patients. Their placement at the proximal and distal tumour borders was compared to tumour demarcations derived from [18F]Fluorodeoxyglucose positron emission tomography, their visibility quantified via the contrast-to-noise ratio on daily orthogonal X-ray imaging, and their mobility relative to bony anatomy analysed by means of retrospective triangulation.
Marker implantation proceeded without complications, but the distal tumour border could not be reached in two patients. Marker locations corresponded reasonably well with metabolic tumour edges (mean: 5.4 mm more distally). Marker visibility was limited but mostly sufficient (mean contrast-to-noise ratio: 1.5), and sixteen markers (84%) remained in situ until the end of treatment. Overall, marker excursions from their planned position were larger than 5(10) mm in 59(17)% of all analysed fractions. On one occasion severe target displacement was only identified via markers and was corrected before treatment delivery.
Implanted helical gold fiducial markers are a safe and reliable method of providing target-centric positioning verification in proton beam therapy of oesophageal carcinoma.

Keywords: oesophageal carcinoma; proton therapy; image-guided radiotherapy; fiducial markers


Publ.-Id: 27921

Thermoeconomic Analysis of a Copper Production Plant - From Mine to Cathode

Reuter, M. A.; Llamasa, A. A.; Stelter, M.; Valero Delgado, A.; Hultgren, M.; Peltomäki, M.; Roine, A.

  • Introduction Circular Economy
  • Exergy as a resource consumption indicator
  • Thermoeconomics
  • Simulation-based exergy and thermoeconomic analysis
  • Extractive metallurgy of copper case
  • Conclusions

Keywords: Circular Economy; Thermoeconomics

  • Invited lecture (Conferences)
    Sustainable Minerals '18 - Towards a circular economy // MEI Conference, 14.-15.06.2018, Windhoek, Namibia

Publ.-Id: 27920

Spin-wave nonreciprocity on magnetization-graded ferromagnetic films

Gallardo, R. A.; Alvarado-Seguel, P.; Schneider, T.; Gonzalez-Fuentes, C.; Roldán-Molina, A.; Lenz, K.; Lindner, J.; Landeros, P.

A theoretical approach has been developed to study the spin-wave dynamics of magnetizationgraded ferromagnetic films, where the magnetic properties change along the film thickness. The theory is based in a multilayer approach, where the influence of both long-range dipolar interactions and interlayer exchange coupling between sublayers is analytically derived, allowing for instance to describe films with continuous variation of the magnetization saturation. A systematic study is carried out in order to analyze different profiles of the magnetic properties along the thickness. It is found that the spin-wave dispersion is significantly modified when the magnetic properties change on the film's bulk, in such a way that a notable frequency nonreciprocity of two counterpropagating spin waves is predicted. Interestingly, the frequency difference exhibits a nonmonothonic behavior that can be positive or negative depending on the wave vector. This is accompanied with heterosymmetric mode profiles and a modification of the conventional quantization condition associated to the perpendicular standing spin-wave modes. Micromagnetic simulations have been carried out to validate the model, where a perfect agreement is reached between both methods. These results show that magnetization-graded ferromagnetic films can be used to channelize and control the spin waves, promoting different kinds of applications for magnon-based devices.

Publ.-Id: 27919

The Circular Economy - Challenges, Opportunities, Limits

Reuter, M. A.

  • Circular Economy (CE) + the origins
  • Circular Economy Engineering (CEE) + System Integrated Metal Production (SIMP)
  • Metallurgical Internet-of-Things (m-loT)
+ Comprehensive flowsheets that integrate product design with physical separation and process metallurgy
+ LED lamps
  • informing Resource Efficiency (iRE)
+ Fairphone

Keywords: Circular Economy; Circular Economy Engineering; Metallurgical Internet-of-Things; Resource Efficiency; Fairphone

  • Lecture (others)
    Circular Economy Design Forum, 28.03.2018, Espoo, Finnland

Publ.-Id: 27918

Dual-energy computed tomography to assess intra- and inter-patient tissue variability for proton treatment planning of brain-tumor patients

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

Background and Purpose:
Range prediction in particle therapy is associated with an uncertainty originating from the calculation of stopping-power ratio (SPR) based on x-ray computed tomography (CT). Here, we assessed the intra- and inter-patient variability of tissue properties in primary brain-tumor patients using dual-energy CT (DECT) and quantified its influence on current SPR prediction.

Material and Methods:
Based on 102 patient DECT scans, SPR distributions were derived from a patient-specific DECT-based approach. Tissue-specific and global deviations between this method and the state-of-the-art CT-number-to-SPR conversion applying a Hounsfield look-up table (HLUT) were quantified. To isolate systematic deviations between both, the HLUT was optimized using DECT. Subsequently, the influence of soft tissue diversity and age-related variations in bone composition on SPR were assessed.

An intra-patient ± inter-patient soft tissue diversity of (4.4±0.7)% in SPR was obtained after conservative consideration of noise-induced variation. Between adults and children younger than 6 years, age-related variations in bone composition resulted in a median SPR difference of approximately 5%.

Patient-specific DECT-based stopping-power prediction can intrinsically incorporate most of the SPR variability arising from tissue mixtures, inter-patient and intra-tissue variations. Since the state-of-the-art HLUT - even after cohort-specific optimization - cannot fully consider the broad tissue variability, patient-specific DECT-based stopping-power prediction is advisable in particle therapy.

Keywords: dual-energy CT; tissue variability; proton therapy


Publ.-Id: 27917

Synemin, a novel regulator of DNA repair machinery and tyrosine kinases in head and neck cancers

Deville, S. S.; Cordes, N.

Introduction: Focal adhesion proteins (FAPs) have been shown to be essential determinants of cancer therapy outcome. Our previous findings revealed the role of FAPs in DNA repair processes. Here, we characterized the unknown and novel functions of Synemin, an intermediate filament protein, which functions as FAP, as novel double strand break (DSB) repair and as tyrosine kinase regulator in head and neck squamous cell carcinoma (HNSCC).
Materials and methods: Using a novel 3D High Throughput RNAi Screen (3D HTP-RNAi-S), clonogenic survival and double strand breaks (DSB) repair in non- and -irradiated HNSCC were analyzed upon knockdown of 117 FAP. Confirmatory data were generated in a panel of 10 HNSCC cell lines. Reporter gene assays were applied to determine the efficiency in DNA DSB repair by non-homologous end joining (NHEJ) and homologous recombination (HR). Western blot was used to determine protein expression and phosphorylation. Immunoprecipitation (IP) and kinase activity profiling (PamGene) were carried out to determine Synemin interactome.
Results and Discussion: Among the potential FAP targets from our 3D HTP-RNAi-S, Synemin turned out as a novel and most promising candidate in controlling HNSCC radiosensitivity. Intriguingly, Synemin depletion induced a 40% reduced NHEJ activity while leaving HR unchanged. We demonstrated significant dephosphorylation of DNA-PKcs kinase, a key component of the NHEJ pathway, as well as reduced levels of Ku70 in Synemin depleted, irradiated HNSCC cells as compared to controls. We further demonstrated an almost comprehensive deactivation of 86 tyrosine kinases after Synemin silencing. Among these, bioinformatic analysis revealed c-Abl highly downregulated at 24 hours post irradiation in Synemin-depleted HNSCC cells. Co-IP revealed an interaction between Synemin and c-Abl suggesting those proteins to form a protein complex. Single, double and triple depletion of Synemin, DNA-PKcs, and c-Abl resulted in similar radiosensitization and DSB levels, suggesting Synemin to be located upstream of these DNA repair kinases.
Conclusion: Our data suggest the intermediate filament Synemin as a novel determinant of DNA repair, tyrosine kinase regulation and radiosensitivity of HNSCC cells. These observations further support the notion that DNA repair is controlled by cooperative interactions between nuclear, membrane and cytoplasmic proteins.

Keywords: Synemin; HNSCC; DNA repair

  • Contribution to proceedings
    International Marie Sklodowska-Curie Meeting: From Radiation to Innovation in Medicine and RADIATE-ITN Student Meeting and Workshop, 11.-13.10.2018, Paris, France

Publ.-Id: 27916

Opportunities and limits of the Circular Econonmy – A metallurgical perspective.

Reuter, M. A.

Rock-to-Metal digitalized and linked to Energy is the Music
The Metal Wheel – A deep understanding is required
Metallurgical Infrastructure Criticality; not only Metal / Element Criticality
Digitalization of the Circular Economy & Analysis
Analyzing the CE system to understand economically the losses on a simulation basis using thermoeconomics & LCA
EU’s Metal Wheel: Develop thermodynamic detail
The Limits of Recycling: Modular design pushing limits

Keywords: Exergy; LCA; thermo-economics; Fairphone; Digitalization

  • Invited lecture (Conferences)
    12th Society And Materials International Conference - SAM 12, 22.-23.05.2018, Metz, Frankreich

Publ.-Id: 27915

No growth without raw materials: Europe must maintain and develop production and recycling technologies.

Reuter, M. A.

The aim of the seminar should be to define the role of regions in shaping a holistic industrial strategy for the EU, particularly with regard to innovation, digitalisation and global competition.
Through a smart, sustainable and inclusive industrial policy, innovative ecosystems are to be promoted in the regions, entrepreneurship encouraged, and jobs created.
Regulatory barriers will need to be dismantled, sustainability ensured, European technological sovereignty preserved and fairness achieved in global competition. To this end, the experience and knowledge of the regions and their proposals for a future EU industrial strategy are indispensable.
The example of Saxony can be used to demonstrate the progress made towards “Industry 4.0” in the fields of microelectronics, e-mobility, material efficiency/resource technologies and advanced manufacturing.

  • Invited lecture (Conferences)
    ECON external Seminar on "Shaping change — towards a holistic industrial strategy", 02.-03.05.2018, Dresden, Deutschland

Publ.-Id: 27914

beta8 integrin determines radiochemoresistance pancreatic cancer cells by regulating autophagy and intracellular vesicle trafficking

Lee, W.-C.; Jin, S.; Cordes, N.

Background: Pancreatic ductal adenocarcinoma (PDAC) is notoriously resistant to radio/chemotherapy and carries the most dismal prognosis among solid tumors with a 5-year relative overall survival rate of approximately 6% and. Thus, there is a great need for molecular-targeting strategies. As cell-matrix adhesion is essential for the survival, invasion and therapy resistance, we sought to identify the function of 117 focal adhesion proteins (FAP) in PDAC cell radioresistance. Intriguingly 8 integrin turned out to be one of the most potential novel targets in PDAC.
Material and methods: We performed a 3D tumor organoid endoribonuclease-prepared siRNA (esiRNA)-based high throughput screening (3DHTesiS) in PDAC cell cultures (established and patient-derived (PDC)) grown in laminin-rich extracellular matrix (IrECM). In addition to characterizing 8 integrin expression, distribution and co-localization with other cellular organelles such as golgi apparatus, tumor organoid forming ability was measured upon 8 integrin knockdown in X-ray (6 Gy) and/or gemcitabine-treated cells. Fiji software was used to determine Peason’s correlation coefficient, vesicle distribution and expression patterns upon irradiation or gemcitabine. An inhibitor screen was conducted to identify pathways involved in the perinuclear-to-cytoplasmic shift of 8 integrin upon treatment. Immunoprecipitation–Mass Spectrometry (IP-MS) was performed to identify 8 integrin interactome upon irradiation.
Results: We identified a series of novel targets including 8 integrin. Without cytotoxicity, 8 integrin depletion elicited radiochemosensitization in PDAC. Intriguingly, we found 8 integrin located in perinuclearly where it colocalize with the cis-Golgi matrix protein GM130. Upon irradiation or gemcitabine, 8 integrin dissociated from the perinuclear region and spread throughout the cytosol by interact with motor proteins including dynein, kinesin, myosin; a process abrogated by microtubule-disturbing agent colchicine. Additionally, 8 integrin depletion reduced PDAC cells autophagy by LC3 turnover assay.
Summary: Our findings, generated in 3D lrECM PDAC organoid cell cultures, suggest 8 integrin as a novel determinant of PDAC radiochemoresistance. Moreover, 8 integrin may facilitate, although not found in the cell membrane to facilitate cell adhesion, a critical role in intracellular vesicle trafficking and co-regulation of autophagy upon irradiation.

Keywords: beta8 integrin; PDAC; irradiation

  • Contribution to proceedings
    International Marie Sklodowska-Curie Meeting: From Radiation to Innovation in Medicine and RADIATE-ITN Student Meeting and Workshop, 11.-13.10.2018, Paris, France

Publ.-Id: 27913

Caveolin–1–mediated regulation of cytoprotective mechanism upon ionizing radiation

Jin, S.; Cordes, N.

The integral membrane protein caveolin–1 (cav1) plays multiple roles in cell physiology and pathology such as endocytosis, signal transduction and tumorigenesis. In cancer, cav1 has a paradoxical function depending on the type of the cancer cells, as an oncogene or as a tumor suppressor. The exact mechanisms by which cav1 controls cancer cell survival are unclear. Our previous studies show that cav1 is overexpressed in human pancreatic ductal adenocarcinoma, contribute to cellular radioresistance and cancer cell survival. In this study, we examined how cav1 co–regulates the repair of radiogenic DNA double strand breaks.

As models, we used normal and radioresistant cancer cells (i.e. MiaPaCa 2 pancreatic cancer cells, PC3 human prostate cancer cells, MCF7 breast cancer cells, and MEFs). We tracked fluorescently tagged cav1 upon x–ray irradiation by performing super resolution live–cell 3D imaging in combination with cell biological, biochemical and biophysical methods. DNA repair was measured in stably 53BP1-GFP-transfected cells as well as staining of 53BP1 and γH2AX.

We found that both cav1 expression and its mobility are correlated with the dynamics of DNA repair upon ionizing radiation in both normal and radioresistant cancer cells. We further confirm that cav1 upregulation is correlated with resistance to x–ray irradiation. Intriguingly, cells irradiated in suspension and subsequently washed prior to co–culturing with unirradiated cells showed significantly less DNA double strand breaks relative to non–co–culture conditions. This cell–to–cell signaling phenomenon was correlated with and conducted through a transfer of cav1 and mitochondria from unirradiated to irradiated cells via intercellular membrane nanotubes.

Cell stress responses can be modulated via multiple pathways. Our data provide insight into the cytoprotective, cell–to–cell and DNA repair–modulating functions of the integral membrane protein cav1. In addition to the “classical” bystander effect mediated by gap junction-related cell–cell contact and soluble factors, intercellular membrane nanotubes serve as a potent and novel survival nexus. Moreover, this mitochondria–cav1 complex and intercellular membrane nanotubes may serve as potential targets for molecular–targeted therapies to overcome radio- and chemoresistance of cancer cells.

Keywords: Caveolin; PDAC; irradiation

  • Contribution to proceedings
    Jahrestagung der GBS, 17.-19.09.2018, Frankfurt am Main, Germany
  • Lecture (Conference)
    DeGBS2019, 23.09.2019, Mannheim, Deutschland

Publ.-Id: 27912

Simulation based life cycle assessment of metallurgical and recycling processes

Reuter, M. A.

Process simulation and environmental softwareare applied to quantify resource efficiency (RE) in a rigorous manner. These digitalisation tools are linked and will be used to show how the environmental performance of copper primary production, the processing of residues and the recycling of e-waste, e.g. light emitting diode (LED) lamps as well as the production of nickel pig iron can be evaluated.

Keywords: HSC; design for recycling; Fairphone; process simulation; recyclability

  • Invited lecture (Conferences)
    Life Cycle Assessment Symposium, 27.04.2018, Freiberg, Deutschland

Publ.-Id: 27911

Limits of the circular economy: Fairphone modular design pushing the limits

Reuter, M. A.; Ballester, M.; van Schaik, A.

The limitations to materials flows from recycling in the circular economy are discussed using as a case a simulation-based analysis of the recyclability of the Fairphone 2. Three different recycling routes are analysed using simulation models that link the bill of materials and full material declarations to the final metal recovery via physical separation models. The recycling and recovery rates are depicted in an innovative recycling index and material flower that helps drive the discussion about the inevitable tradeoffs between the recyclability of different target materials and debunks the myth of a total recyclability of materials. Modular design is shown to have clear recycling as well as environmental advantages. This study is part of the SustainablySMART project.This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 680640. © 2018 GDMB Gesellschaft fur Bergbau, Metallurgie, Rohstoff- und Umwelttechnik e.V. All rights reserved.

Keywords: Circular economy; Design for recycling; Fairphone; Recycling-index; Simulation

  • World of Metallurgy - Erzmetall 2(2018)71, 68-79
  • Invited lecture (Conferences)
    Sustainable Minerals '18 - Towards a circular economy // MEI Conference, 14.-15.06.2018, Windhoek, Namibia

Publ.-Id: 27909

Long-term stability of the microstructure of austenitic ODS steel rods produced with a carbon-containing process control agent

Gräning, T.; Klimenkov, M.; Rieth, M.; Heintze, C.; Möslang, A.

Oxide dispersion strengthened (ODS) steels have proven to be a viable candidate as a structural material in a fusion power plant, due to their enhanced mechanical properties and resilience under irradiation and at high temperatures. A high interest in the development of austenitic ODS (AODS) steel became noticeable, which is shown by the increased amount of publications in that field in the recent years. That can be related to the inherently better corrosion resistance and superior creep properties compared to its ferritic counterpart. However, one of the major drawbacks of AODS steels was the more challenging mechanical alloying (MA) process and a lower powder production yield, caused by a more ductile and adhesive powder. This disadvantage was tackled by the addition of a process control agent (PCA) during the MA, but it was yet to be shown how the addition of a PCA affects the microstructure of the AODS.

AODS with a carbon-containing PCA was mechanical alloyed, hot-extruded, and subsequently annealed at 700, 900, and 1100 °C for 2, 750, 1000, 1250 and 1500 hours to investigation the influence of carbon on the formation and stability of precipitates as well as on the grain size in comparison to available literature data. Scanning and transmission electron microscopy and atom probe tomography methods were applied in this systematic study to identify the possible growth of nano-precipitates. An Arrhenius-equation was used to determine the activation energy of the growth of precipitates.

Results and Discussion:
A growth of precipitates is barely detectable at temperatures equal or lower than 900 °C. The grain size remains stable. However, an unexpected increase of the grain and precipitates sizes and a decreased activation energy was measured at temperatures of 1100 °C for all annealing times. Recently published results of similar AODS steels have shown a stability of the microstructure up to 1250 °C. Due to this contradiction, we concluded that the growth of precipitates and the reduction of the grain boundary pinning force was supported by the diffusion of carbon and the formation of carbides.

  • Lecture (Conference)
    NuMat 2018, 14.-18.10.2018, Seattle, USA
  • Journal of Nuclear Materials 523(2019), 111-120
    DOI: 10.1016/j.jnucmat.2019.05.060

Publ.-Id: 27908

On the role of Ni, Si and P on the microstructural evolution of FeCr alloys under irradiation

Gómez-Ferrer, B.; Heintze, C.; Pareige, C.

In this experimental work the behaviour of Ni, Si and P, typical impurities or low alloying elements in ferritic/martensitic nuclear steels, with increasing irradiation dose was investigated in model FeCrX (X = Ni, Si, P, NiSiP) alloys using atom-probe 3D maps. These elements are known to increase the embrittlement and the hardening of steels by segregating at internal surfaces and creating solute-rich clusters at 300°C. This study is focused on the analysis of the clusters and the influence of every chemical specie in their formation. The model alloys have been irradiated with 5 MeV Fe2+ ions up to 0.1 and 0.5 dpa at 300°C and the 3D atom maps have been analysed using statistical tools and iso-concentration algorithms. P is proven to be the fastest diffuser whereas Ni and Si are slower. The three species segregate together strengthening the idea that they are decorating stable defect clusters by dumbbell or vacancy dragging. And no apparent influence on the clustering of every element over the others is observed up to 0.1dpa, suggesting the absence of synergistic effect between these species.

Publ.-Id: 27907

The (Geo) Metallurgy of the Circular Economy

Reuter, M. A.

Circular economy (CE) is defined here in terms of the metallurgical Internet of Things (m-IoT). This is the digitalized Web of Metals (WoM) or, in other words, the system integrated material production (SIMP). Its digitalization provides the real-time detail that quantifies the three pillars of sustainability: social, environmental, and economical. This is termed ‘‘circular economy engineering’’ (CEE), i.e., the digitalization of the CE, using among others the theory and technology of minerals processing, metallurgy, recycling, computer-aided engineering (CAE), and product design. This provides the basis for the estimation of the metrics of resource efficiency (RE) and, hence, provides a direction for innovation and also enables the m-IoT.

Geometallurgy is now largely accepted as the process to quantify and understand a mineral deposit in terms of its structure, composition and ultimately to determine its economic value.
Geometallurgy 2018 will bring together experts from academia and industrial research, practitioners from operating mines, consultants and contractors as well as industry bodies with the aim of increasing the understanding and value of mineral assets.

Keywords: Circular economy; digitalization; metallurgy; recycling; resource efficiency

  • Invited lecture (Conferences)
    GEOMETALLURGY 2018, 19.-20.04.2018, London, Großbritannien

Publ.-Id: 27906

Redirecting switchable UniCAR T cells for elimination of radioresistant cancer cells

Feldmann, A.; Arndt, C.; Bergmann, R.; Berndt, N.; Jureczek, J.; Albert, S.; Lindner, D.; Koristka, S.; Steinbach, J.; Ehninger, G.; Krause, M.; Kurth, I.; Dubrovska, A.; Bachmann, M.

Radiation therapy represents a commonly applied treatment regimen for solid tumors. Unfortunately, it is often accompanied by a high risk for the outgrowth of radioresistant cancer cells against which treatment options are limited. We challenged the idea whether or not chimeric antigen receptor (CAR)-modified T cells could be exploited as an adjuvant immunotherapy in combination with standard radiotherapy. Over the past several years, we have established switchable universal CAR constructs (UniCARs) that recognize a short peptide epitope (E5B9) which does not exist on the surface of living cells. UniCAR T cells are redirected to malignant cells exclusively in the presence of a target module (TM) that contains the epitope E5B9 and specifically binds to a tumor-associated antigen (TAA) on the tumor cell surface.
For providing a rationale for the combination of CAR and radiation therapy, we used different radioresistant sublines of the head and neck cancer cell line Cal33. Expression of various TAAs including of PSCA, EGFR and CD98 was confirmed by flow cytometry analysis. Subsequently, TMs recognizing these potential targets were generated from the variable domains of monoclonal antibodies, cloned into lentiviral vectors and purified from cell culture supernatants of TM-producing stable cell lines. In parallel, T cells isolated from healthy donors were engrafted with UniCARs by lentiviral transduction. Armed with our anti-TAA TMs, UniCAR T cells efficiently lysed radioresistant Cal33 tumor cells both in vitro and in vivo.
Taken together, we could demonstrate that radioresistant cancer cells can effectively be killed by retargeting UniCAR T cells against PSCA, CD98 and EGFR. Thus, resistance to standard of care radiotherapy can be overcome by concomitant or subsequent immunotherapy using the flexible UniCAR technology.

Keywords: radiation therapy; immunotherapy; chimeric antigen receptors

  • Lecture (Conference)
    ICLE 2018, International Conference on Lymphocyte Engineering 2018, 13.-15.09.2018, Madrid, Spanien
  • Open Access Logo Abstract in refereed journal
    Human Gene Therapy 29(2018)11, ICLE8-0040
    DOI: 10.1089/hum.2018.29071.abstracts

Publ.-Id: 27904

Directionality of nickel-induced layer exchange during graphitization in carbon-nickel thin films

Janke, D.; Wenisch, R.; Munnik, F.; Hübner, R.; Grenzer, J.; Gemming, S.; Rafaja, D.; Krause, M.

Metal-induced crystallization with layer exchange (MIC w LE) can reduce the crystallization temperature of group 14 elements by several hundred degrees. This is especially interesting for device fabrication on substrates with limited thermal stability. Ideally, the process allows the transfer of defined amounts of an initially amorphous material onto a randomly selected substrate. In this contribution, MIC w LE is studied for Ni/ a-C thin films with different stacking sequences in order to quantify the influence of the stacking sequence on the layer exchange degree αLE and on the degree of graphitic ordering. The process was monitored in situ by temperature-dependent Rutherford backscattering spectrometry (RBS) and Raman spectroscopy up to 700 °C. RBS, Raman, elastic recoil detection, X-ray diffraction and transmission electron microscopy were applied for ex situ characterization.
The highest αLE of 96% was found for the initial Ni/a-C stacking sequence. In contrast, the inverse sequence resulted in an incomplete LE. The formation of 2D-layered carbon structures occurred independently of the initial stacking sequence.1 Beyond the threshold of 580 °C, increasing the temperature to up to 700 °C had a negligible impact on the degree of 2D-ordering. Since LE and graphitization occur simultaneously at high temperatures, MIC w LE rather than dissolution/ precipitation is proposed as responsible mechanism for carbon crystallization.

Keywords: metal-induced crystallization; directionality; amorphous carbon; nickel; graphitization; layer exchange; ERD; Raman; TEM

  • Lecture (Conference)
    Flatlands 2018, 03.-07.09.2018, Leipzig, Deutschland

Publ.-Id: 27903

Digitalizing the Circular Economy - Metallurgical process system is the carrier

Reuter, M. A.

Metallurgy is a key enabler of a circular economy (CE), its digitization 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 digitization. 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.

Keywords: circular economy; digitization; recycling; resource efficiency; sustainability

  • Invited lecture (Conferences)
    8th Forum of Non-Ferrous Metals, 21.-23.02.2018, Krakau, Polen

Publ.-Id: 27902

Digitalizing the Circular Economy - Fairphone as example

Reuter, M. A.

The limitations to materials flows from recycling in the circular economy are discussed using as a case a simulation-based analysis of the recyclability of the Fairphone 2. Three different recycling routes are analysed using simulation models that link the bill of materials and full material declarations to the final metal recovery via physical separation models. The recycling and recovery rates are depicted in an innovative recycling index and material flower that helps drive the discussion about the inevitable trade-offs between the recyclability of different target materials and debunks the myth of a total recyclability of materials. Modular design is shown to have clear recycling as well as environmental advantages. This study is part of the SustainablySMART project.

Keywords: Circular Economy; Design for Recycling; Fairphone; Simulation; Recycling-Index

  • Invited lecture (Conferences)
    Circular Materials Conference, 07.-08.03.2018, Göteborg, Schweden

Publ.-Id: 27901

Simulation based Design for Recycling - Fairphone as an example

Reuter, M. A.

The limitations to materials flows from recycling in the circular economy are discussed using as a case a simulation-based analysis of the recyclability of the Fairphone 2. Three different recycling routes are analysed using simulation models that link the bill of materials and full material declarations to the final metal recovery via physical separation models. The recycling and recovery rates are depicted in an innovative recycling index and material flower that helps drive the discussion about the inevitable tradeoffs between the recyclability of different target materials and debunks the myth of a total recyclability of materials. Modular design is shown to have clear recycling as well as environmental advantages. This study is part of the SustainablySMART project.

Keywords: Circular Economy; Design for Recycling; Fairphone; Simulation; Recycling-Index

  • Invited lecture (Conferences)
    Berliner Recycling- und Rohstoffkonferenz, 19.03.2018, Berlin, Deutschland

Publ.-Id: 27900

Neoadjuvant radiochemotherapy significantly alters the phenotype of plasmacytoid dendritic cells and 6-sulfo LacNAc+ monocytes in rectal cancer

Wagner, F.; Hölig, U.; Wilczkowski, F.; Sommer, U.; Wehner, R.; Kießler, M.; Jarosch, A.; Plesca, I.; Flecke, K.; Arsova, M.; Tunger, A.; Bogner, A.; Reißfelder, C.; Weitz, J.; Schäkel, K.; Troost, E.; Krause, M.; Folprecht, G.; Bornhäuser, M.; Bachmann, M.; Aust, D.; Baretton, G.; Schmitz, M.

Neoadjuvant radiochemotherapy (nRCT) can significantly influence the tumor immune architecture that plays a pivotal role in regulating tumor growth. Whereas various studies have investigated the effect of nRCT on tumor-infiltrating T cells, little is known about its impact on the frequency and activation status of human dendritic cells (DCs). Plasmacytoid DCs (pDCs) essentially contribute to the regulation of innate and adaptive immunity and may profoundly influence tumor progression. Recent studies have revealed that higher pDC numbers are associated with poor prognosis in cancer patients. 6-sulfo LacNAc-expressing monocytes (slanMo) represent a particular proinflammatory subset of human non-classical blood monocytes that can differentiate into DCs. Recently, we have reported that activated slanMo produce various proinflammatory cytokines and efficiently stimulate natural killer cells and T lymphocytes. slanMo were also shown to accumulate in clear cell renal cell carcinoma and in metastatic lymph nodes from cancer patients.
In the present study, we investigated the influence of nRCT on frequency and phenotype of rectal cancer-infiltrating pDCs and slanMo. When evaluating rectal cancer tissues obtained from patients after nRCT, a significantly higher frequency of pDCs in comparison to non-matched pre-nRCT tissue samples was found. In contrast, the density of slanMo was not significantly altered by nRCT. These findings were confirmed when analyzing matched pre-nRCT and post-nRCT rectal cancer specimens. Further studies revealed that nRCT significantly increases the percentage of mature CD83+ pDCs in rectal cancer tissues. Moreover, the proportion of pDCs locally expressing interferon-alpha, which plays a major role in antitumor immunity, was significantly higher in post-nRCT. In addition, nRCT markedly enhanced the percentage of inducible nitric oxide synthase- or tumor necrosis factor alpha-producing slanMo in rectal cancer tissues. These novel findings indicate that nRCT significantly influences the frequency and/or phenotype of pDCs and slanMo, which may influence the clinical response of rectal cancer patients to nRCT.

Keywords: plasmacytoid dendritic cells; 6-sulfo LacNAc+ monocytes; tumor immune architecture; radiochemotherapy; rectal cancer

Publ.-Id: 27899

Structure-property relationship of Co2MnSi thin films in response to He+-irradiation

Hammerath, F.; Bali, R.; Hübner, R.; Brandt, M. R. D.; Rodan, S.; Potzger, K.; Böttger, R.; Sakuraba, Y.; Büchner, B.; Wurmehl, S.

We investigated the structure-property relationship of Co2MnSi Heusler thin films upon the irradiation with He+ ions. The variation of the crystal structure with increasing ion fluence has been probed using nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM), and associated with the corresponding changes of the magnetic behavior. A decrease of both the structural order and the moment in saturation is observed. Specifically, we detect a direct transition from a highly L21-ordered to a fully A2-disordered structure type and quantify the evolution of the A2 structural contribution as a function of ion fluence. Complementary TEM analysis reveals a spatially-resolved distribution of the L21 and A2 phases showing that the A2 disorder starts at the upper part of the films. The structural degradation in turn leads to a decreasing magnetic moment in saturation in response to the increasing fluence.

Keywords: Structure-property relationship; Heusler; thin films; Ion irradiation

  • Open Access Logo Scientific Reports 9(2019), 2766
    DOI: 10.1038/s41598-019-39435-4
  • Lecture (Conference)
    DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM) gemeinsam mit der European Physical Society (CMD), 11.-16.03.2018, Berlin, Deutschland

Publ.-Id: 27898

Data Analysis and Machine Learning at the Computational Science Group

Kelling, J.

In this talk I will summarize the current activities of the computational science group at HZDR, which range from establishing research data publication (RODARE) and management platforms to providing numerical and computational expertise in various research projects. The latter aspect will be presented in detail through two selected ongoing projects.

In a project with the institute for resource ecology at HZDR, we developed a framework for the analysis of spectra of mixed solutions. The goal of the analysis is to discover how many species are in a given sample and in what concentration while at the same time extracting their unknown spectrum. A number of numerical techniques can be employed to this end, each requiring different amounts prior knowledge and different types of measurements. Here the primary task of the analysis framework is to unify a zoo of different implementations of similar methods and making all methods available to all scientists. Additionally, it enables simple use of remote computing resources, which allow for more computationally intensive analysis which can add a more reliable way to estimate confidence bounds.

In another project, we are using deep learning approaches to develop an automated safety system for the high-power laser systems DRACO and PENELOPE at HZDR. Here the goal is to detect defects or scatterers which focus parts of a yet unfocussed beam. These can, when left unchecked, cause cascades of failing mirrors, lenses, and non-linear crystals and should thus be detected in the time between two shots. This work uses deep convolutional neural networks implemented through the Caffe framework to achieve real-time detection and localization of impurities in the beam profile.

Keywords: computational science; data management; machine learning

  • Lecture (Conference)
    IHRS NanoNet Annual Workshop, 05.-07.09.2018, Bad Gottleuba, Deutschland

Publ.-Id: 27897

Applicability of a prognostic CT-based radiomic signature model trained on stage I-III non-small cell lung cancer in stage IV non-small cell lung cancer

de Jonga, E.; van Elmpt, W.; Rizzo, S.; Colarieti, A.; Spitaleri, G.; Leijenaar, R.; Jochems, A.; Hendriks, L.; Troost, E.; Reymen, B.; Dingemans, A.-M.; Lambin, P.

Recently it has been shown that radiomic features of computed tomography (CT) have prognostic information in stage I-III non-small cell lung cancer (NSCLC) patients. We aim to validate this prognostic radiomic signature in stage IV adenocarcinoma patients undergoing chemotherapy.
Materials and Methods
Two datasets of chemo-naive stage IV adenocarcinoma patients were investigated, dataset 1: 285 patients with CTs performed in a single center; dataset 2: 223 patients included in a multicenter clinical trial. The main exclusion criteria were EGFR mutation or unknown mutation status and non-delineated primary tumor. Radiomic features were calculated for the primary tumor. The c-index of cox regression was calculated and compared to the signature performance for overall survival (OS).
In total CT scans from 195 patients were eligible for analysis. Patients having a Prognostic Index (PI) lower than the signature median (n = 92) had a significantly better OS than patients with a PI higher than the median (n = 103, HR 1.445, 95% CI 1.07-1.95, p = 0.02, c-index 0.576, 95% CI 0.527-0.624).
The radiomic signature, derived from daily practice CT scans, has prognostic value for stage IV NSCLC, however the signature performs less than previously described for stage I-III NSCLC stages. In the future, machine learning techniques can potentially lead to a better prognostic imaging based model for stage IV NSCLC.

Keywords: stage IV NSCLC; prognostic model; Radiomics; CT

Publ.-Id: 27896

CT imaging during treatment improves radiomic models for patients with locally advanced head and neck cancer

Leger, S.; Zwanenburg, A.; Pilz, K.; Zschaeck, S.; Zöphel, K.; Kotzerke, J.; Schreiber, A.; Zips, D.; Krause, M.; Baumann, M.; Troost, E.; Richter, C.; Löck, S.

Background and purpose: The development of radiomic risk models to predict clinical outcome is usually based on pre-treatment imaging, such as computed tomography (CT) scans used for radiation treatment planning. Imaging data acquired during the course of treatment may improve their prognostic performance. We compared the performance of radiomic risk models based on the pre-treatment CT and CT scans acquired in the second week of therapy.
Material and methods: Treatment planning and second week CT scans of 78 head and neck squamous cell carcinoma patients treated with primary radiochemotherapy were collected. 1538 image features were extracted from each image. Prognostic models for loco-regional tumour control (LRC) and overall survival (OS) were built using 6 feature selection methods and 6 machine learning algorithms. Prognostic performance was assessed using the concordance index (C-Index). Furthermore, patients were stratified into risk groups and differences in LRC and OS were evaluated by log-rank tests.
Results: The performance of radiomic risk model in predicting LRC was improved using the second week CT scans (C-Index: 0.79), in comparison to the pre-treatment CT scans (C-Index: 0.65). This was confirmed by Kaplan–Meier analyses, in which risk stratification based on the second week CT could be improved for LRC (p = 0.002) compared to pre-treatment CT (p = 0.063).
Conclusion: Incorporation of imaging during treatment may be a promising way to improve radiomic risk models for clinical treatment adaption, i.e., to select patients that may benefit from dose modification.

Keywords: Radiomic risk modelling; Computed tomography; Imaging during treatment; Patient stratification


Publ.-Id: 27895

Radiation dose constraints for organs at risk in neuro-oncology; the European Particle Therapy Network consensus

Lambrecht, M.; Eekers, D.; Alapetite, C.; Burnet, N.; Calugaru, V.; Coremans, I.; Fossati, P.; Høyer, M.; Langendijk, J.; Romero, A. M.; Paulsen, F.; Perpar, A.; Renard, L.; de Ruysscher, D.; Timmermann, B.; Vitek, P.; Weber, D.; van der Weide, H.; Whitfield, G.; Wiggenraad, R.; Roelofs, E.; Nyström, P. W.; Troost, E.

For unbiased comparison of different radiation modalities and techniques, consensus on delineation of radiation sensitive organs at risk (OARs) and on their dose constraints is warranted. Following the publication of a digital, online atlas for OAR delineation in neuro-oncology by the same group, we assessed the brain OAR-dose constraints in a follow-up study.
We performed a comprehensive search to identify the current papers on OAR dose constraints for normofractionated photon and particle therapy in PubMed, Ovid Medline, Cochrane Library, Embase and Web of Science. Moreover, the included articles' reference lists were cross-checked for potential studies that met the inclusion criteria. Consensus was reached among 20 radiation oncology experts in the field of neuro-oncology.
For the OARs published in the neuro-oncology literature, we summarized the available literature and recommended dose constraints associated with certain levels of normal tissue complication probability (NTCP) according to the recent ICRU recommendations. For those OARs with lacking or insufficient NTCP data, a proposal for effective and efficient data collection is given.
The use of the European Particle Therapy Network-consensus OAR dose constraints summarized in this article is recommended for the model-based approach comparing photon and proton beam irradiation as well as for prospective clinical trials including novel radiation techniques and/or modalities.

Keywords: Dose constraints; Organs at risk; Particle therapy; European Particle Therapy Network

Publ.-Id: 27894

In vivo imaging in the oral cavity by endoscopic optical coherence tomography

Walther, J.; Schnabel, C.; Tetschke, F.; Rosenauer, T.; Golde, J.; Ebert, N.; Baumann, M.; Hannig, C.; Koch, E.

The common way to diagnose hard and soft tissue irregularities in the oral cavity is initially the visual inspection by an experienced dentist followed by further medical examinations, such as radiological imaging and/or histopathological investigation. For the diagnosis of oral hard and soft tissues, the detection of early transformations is mostly hampered by poor visual access, low specificity of the diagnosis techniques, and/or limited feasibility of frequent screenings. Therefore, optical noninvasive diagnosis of oral tissue is promising to improve the accuracy of oral screening. Considering this demand, a rigid handheld endoscopic scanner was developed for optical coherence tomography (OCT). The novelty is the usage of a commercially near-infrared endoscope with fitting optics in combination with an established spectral-domain OCT system of our workgroup. By reaching a high spatial resolution, in vivo images of anterior and especially posterior dental and mucosal tissues were obtained from the oral cavity of two volunteers. The convincing image quality of the endoscopic OCT device is particularly obvious for the imaging of different regions of the human soft palate with highly scattering fibrous layer and capillary network within the lamina propria

Keywords: optical coherence tomography; endoscopic imaging; dentistry; medical and biological imaging optics; medical optics instrumentation; tissue

Publ.-Id: 27893

Independent validation of a new reirradiation risk score (RRRS) for glioma patients predicting post-recurrence survival: A multicenter DKTK/ROG analysis

Niyazi, M.; Adeberg, S.; Kaul, D.; Boulesteix, A.; Bougatf, N.; Fleischmann, D.; Grün, A.; Krämer, A.; Rödel, C.; Eckert, F.; Paulsen, F.; Kessel, K.; Combs, S.; Oehlke, O.; Grosu, A.; Seidlitz, A.; Lattermann, A.; Krause, M.; Baumann, M.; Guberina, M.; Stuschke, M.; Budach, V.; Belka, C.; Debus, J.

Background and purpose: Reirradiation (reRT) is a valid option with considerable efficacy in patients with recurrent high-grade glioma, but it is still not known which patients might be optimal candidates for a second course of irradiation. This study validated a newly developed prognostic score independently in an external patient cohort.
Material and methods: The reRT risk score (RRRS) is based on a linear combination of initial histology, clinical performance status, and age derived from a multivariable model of 353 patients. This score can predict post-recurrence survival (PRS) after reRT. The validation dataset consisted of 212 patients.
Results: The RRRS differentiates three prognostic groups. Discrimination and calibration were maintained in the validation group. Median PRS times in the development cohort for the good/intermediate/poor risk categories were 14.2, 9.1, and 5.3 months, respectively. The respective groups within the validation cohort displayed median PRS times of 13.8, 8.8, and 3.8 months, respectively. Uno's C for development data was 0.64
(CI: 0.60-0.69) and for validation data 0.63 (CI: 0.58-0.68).
Conclusions: The RRRS has been successfully validated in an independent patient cohort. This linear combination of three easily determined clinicopathological factors allows for a reliable classification of patients and may be used as stratification factor for future trials.

Publ.-Id: 27891

Peptide für die spezifische Interaktion mit Mineralen

Lederer, F. L.; Braun, R.; Pollmann, K.

Recycling ist eine wichtige Komponente der Kreislaufwirtschaft, um Ressourcen zu schonen.
Auch die Biologie wird dazu zukünftig ihren Beitrag leisten. Dabei steht das Recycling von Edelmetallen und Selten-Erd-Elementen (SEE), die in Elektronikprodukten verbaut sind, im Mittelpunkt eines Forschungszweigs der Abteilung Biotechnologie am Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF).

  • ACAMONTA - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 25(2018), 60-63

Publ.-Id: 27890

Identification of Peptides as alternative recycling tools via Phage Surface Display – How biology supports Geosciences

Lederer, F. L.; Braun, R.; Schöne, L. M.; Pollmann, K.

The application of biological tools in Geosciences such as bacteria or microbial products that mobilize metallic components raises increasing interest in classical mining industries. Today, 10% of the total copper production in Chile originated from bioleaching operations (Gentina and Acevedo, 2016). However, the application of biological tools is limited due to poor specificity, complex material composition and heterogenous particle size. New studies focus on smaller biological components such as peptides with higher material specificity to mobilize and recycle materials of interest.
End-of-life electronic products like smart phones or compact fluorescent lamps (CFL) contain a wide variety of precious elements in very low concentrations. Currently, no cost-efficient and environmentally friendly technology exists for the separation and recycling of the majority of high-tech industry supporting elements such as the rare earth element (REE) Lanthanum phosphate (LAP) from electronic scrap. The focus of this project was the identification of peptides with high specificity for the rare earth mineral LAP, a component of CFL, for future material recycling. By using a biological method called phage surface display and the random PVIII phage peptide library f88.4/Cys6, the phage-bound peptide TSTQCPSHIRACLKKR was identified and characterized as not only an efficient LAP binder, which is furthermore able to discriminate between LAP and other components of fluorescent lamps. The application of phage particles displaying the recombinant PVIII fused peptide TSTQCPSHIRACLKKR in recycling processes is not possible due to limited scale-up, critical public perception, low biological efficiency and fast mutation rates in phage particles. Future applications will be based on peptides that are stable under a variety of challenging conditions such as heat, varying pH or in the presence of toxic scrap components. The development of peptide-based separation tools represents a new way of recycling of electronic scrap.

Keywords: LaPO4:Ce; Tb; phage surface display; peptide; recycling; rare earth element

Publ.-Id: 27889

Synthese Dipeptid-abgeleiteter Alkine als irreversible Inhibitoren von Cathepsin B

Trapp, C.

Die hier dargelegte Arbeit knüpft an den bereits vorhandenen Erkenntnissen unserer Forschungsgruppe am HZDR an und gründet auf den bisherigen Arbeiten von L. Behring. Der Schwerpunkt dieser Forschungsgruppe liegt auf der Hemmung von Cathepsin B, einem in malignen Tumoren überexprimierten Enzym. Durch die Arbeiten von GREENSPAN et al. konnte bisher gezeigt werden, dass der nitrilfunktionalisierte Inhibitor mit einem Carboxybenzyl-Rest in P1 und einem 3-Methylphenyl-Rest in P2 sich besonders für die Hemmung des Enzyms eignet. Ausgehend von diesen Erkenntnissen sollte das durch GREENSPAN et al. synthetisierte Molekül als Leitstruktur verwendet werden, um daraus irreversible alkinfunktionalisierte Inhibitoren zu synthetisieren. Der Vorteil dieser Inhibitoren ist, dass sie sich, im Gegensatz zu Nitrilen, nicht vom Target ablösen. Um einen Vergleich in ihrer Hemmwirkung festzustellen, sollten die analogen reversibel bindenden nitrilfunktionalisierten Inhibitoren hergestellt werden. Im Vorfeld wurde bereits der alkinfunktionalisierte Inhibitor der analogen Greenspan-Verbindung synthetisiert. Da dieser jedoch als Diastereomerengemisch vorlag, stand die Synthese stereo-chemisch reiner alkinfunktionalisierte Inhibitor im Vordergrund. Die enzymatischen Messungen der synthetisierten Inhibitoren übernahm L. Behring. Die im Folgenden diskutierten Ergebnisse aus den Messungen sind in Tabelle 3 zusammengefasst.
Die Synthese des nitrilfunktionalisierten Inhibitors mit 4-Fluorbenzoyl-Rest in P3, 3-Methylphenylalanyl-Rest in P2 und zwei Protonen in P1 gestaltete sich schwieriger, als die des analogen Alkin-Derivats. In den RP-HPLC-Spektren des nitrilfunktionalisierten Inhibitors konnten, besonders während der Boc-Entschützung, viele Nebenprodukten nachgewiesen werden. Diese entstanden aufgrund der höheren Elektrophile der Nitrilgruppe. Diese Nebenprodukte bedeuteten eine zusätzliche Reinigung, welche sich auf die Ausbeuten auswirkte. Es wurde daher für die weiteren nitrilfunktionalisierten Inhibitoren beschlossen, die Dehydratisierung des weniger reaktiveren Amids zum Nitril auf das Ende der Synthese zu planen. Die Ausbeute des nitrilfunktionalisierten Inhibitors lag über drei Schritte bei 30 %. Im Vergleich dazu wurde der alkinfunktionalisierte Inhibitor mit 60 % über drei Schritte erhalten. Der bestimmte Ki-Wert zeigte für den nitrilfunktionalisierten Inhibitor 6 einen Wert von 1,19 µM. Der analog synthetisierte alkinfunktionalisierte Inhibitor 3 zeigte keine enzymatische Hemmung. Es ist davon auszugehen, dass dieser unzureichend im Enzym fixiert wurde und die Addition des Thiolats im aktiven Zentrum an das Alkin nicht stattfinden konnte.
Die zweite Gruppe der synthetisierten Inhibitoren unterschied sich im Rest P1 zu den Vorangegangenen. Es konnte gezeigt werden, dass die Inhibitorwirkung mit zwei Protonen in Position P1 für nur geringe Hemmung am Cathepsin B sorgt. Durch die Arbeiten von GREENSPAN et al. wurde daher der Carboxybenzylserin-Baustein in P1 gewählt. Die Synthese des nitrilfunktionalisierten Inhibitors verlief über eine zehnstufige Synthese und brachte eine Ausbeute von 8 % hervor. Der größte Verlust bei der Synthese von 16 und 30 wurde in der Alkylierung des Serin-Bausteins mit dem allylgeschützten Carboxybenzyl-Rest beobachtet. Die Reaktion verlief nur mit Ausbeuten von ca. 30 % (Verbindung 16) bzw. 40 % (Verbindung 30) und bereitete während der Synthese die meisten Schwierigkeiten. In der Arbeit wurden daher verschiedene Reaktionsbedingungen getestet. Im Falle des nitrilfunktionalisierten Inhibitors 16 wurde die Temperatur für die Deprotonierung variiert, wobei mit sinkender Temperatur die alkylierende Veresterung des Boc-geschützten Serins der Seitenkettenalkylierung vorgezogen wird. Das entstandene Esterprodukt wurde isoliert, spektroskopisch untersucht und mit dem der alkylierten Verbindung verglichen. Im Falle des alkinfunktionalisierten Inhibitors 30 wurde ebenfalls die Temperatur und die Zeit für die Deprotonierung untersucht. Es konnte gezeigt werden, dass die Temperatur während der Deprotonierung wenig Einfluss auf die Reaktion besitzt. Anders war es bei der Zeit für die Deprotonierung. Hier wurde durch 1H-NMR-Auswertung und RP-HPLC gezeigt, dass sich bei langen Deprotonierungszeiten ein intramolekular entstandenes Oxazolidinon bildete, welches durch anschließende Zugabe des Alkylierungsmittels zur N-Alkylierung neigt.
Die ansonsten stereokonservative Synthese, ausgehend vom L-Serin über den Garner-Aldehyd verlief mit hohen Ausbeuten und einfachen Reinigungsschritten. Die spektroskopische Mosher-Säure-Analyse des rückreduzierten Garner-Aldehyds zeigte, dass die stereochemische Integrität während der Aldehyd-Synthese erhalten blieb. Auch nach der Kupplung zum Dipeptid und damit der Einführung eines zweiten Stereozentrums konnten nur geringe Peakdopplungen (Anteil ≤ 4 % des ungewünschten Diastereomers) im 1H-NMR nachgewiesen werden. Die Messung des Dipeptidalkins 30 führte ebenfalls zum Erfolg. Es konnte durch die Messung am isolierten Enzym bewiesen werden, das er eine irreversible Bindung mit dem Enzym eingeht. Durch vorangegangene Arbeiten unserer Arbeitsgruppe konnte außerdem gezeigt werden, dass sich das Molekül mit 4-Fluorbenzoyl-Rest in P3 besser eignet als das bereits hergestellte Epimerengemisch mit 2,4-Difluorbenzoylrest in P3.
Der fünfte Inhibitor 40 wurde ausgehend vom kommerziell erhältlichen Propargylserin synthetisiert. Die Reaktion verlief mit 9 % Ausbeute über acht Reaktionsschritte. Die Synthese des Inhibitors verlief trotz geringerer Ausbeuten nahezu unproblematisch. Der letzte Schritt der Methylester-Entschützung bereitete zunächst Probleme, wobei es zur partiellen Racemisierung des Inhibitors kam. Diese konnten jedoch durch Verkürzen der Reaktionszeit und Einsatz der Base im Unterschuss fast komplett unterdrückt werden. Der Inhibitor konnte, ähnlich wie das Dipeptidalkin 30 mit ≤ 3 % des unerwünschten Diastereomers synthetisiert werden. Da der Triazol-Inhibitor 40 schlechter ist als der mit einem Proton in P1 (Verbindung 6), ist die Synthese des entsprechenden Alkins nur wenig aussichtsvoll. Durch die unzureichende Bindung des Inhibitors in den Enzymtaschen ist, wie bei Inhibitor 6, keine irreversible Bindung zu erwarten. Ein Ausblick ist die stereoisomerenreine Synthese des 2,4-difluorbenzoylierten Inhibitors zum direkten Vergleich mit dem analogen Diastereomerengemisch. Weiterhin soll der Rest in P3 durch ein 4-Phenylbenzoyl-Rest ersetzt werden. Dieser besitzt ein größeres π-Elektronensystem, wodurch die Wechselwirkungen mit den π-Elektronen des Tyrosins in der Enzymtasche S3 verbessert werden sollen. Da anschließend eine Radiomarkierung der Verbindung erfolgen soll, bietet es sich an, den analogen 4-(4-Fluorbenzyl)-benzoyl-Rest an die Position P3 zu binden. Eine weitere Modifikation, wäre die Än-derung des P2-Rests von Methylphenylalanin zu Monoiodtyrosin. In den Arbeiten von XING et al. zeigten Tyrosin-Derivate, speziell die iodierten Tyrosin-Derivate eine besonders potente Hemmwirkung gegenüber Cathepsin B. Dieser Substituent könnte eine verbesserte Wechselwirkung mit der Aminosäure Glutaminsäure (Glu 245) in Enzymtasche S2 bewirken.

  • Master thesis
    Hochschule Zittau/Görlitz, 2017
    Mentor: Prof. Dr. Dieter Greif, Dr. Reik Löser
    193 Seiten

Publ.-Id: 27888

Extended Infrared Photoresponse in Te-Hyperdoped Si at Room Temperature

Wang, M.; Berencén, Y.; García-Hemme, E.; Prucnal, S.; Hübner, R.; Yuan, Y.; Xu, C.; Rebohle, L.; Böttger, R.; Heller, R.; Schneider, H.; Skorupa, W.; Helm, M.; Zhou, S.

Presently, silicon photonics requires photodetectors that are sensitive in a broad infrared range, can operate at room temperature, and are suitable for integration with the existing Si-technology process. Here, we demonstrate strong room-temperature sub-band-gap photoresponse of photodiodes based on Si hyperdoped with tellurium. The epitaxially recrystallized Te-hyperdoped Si layers are developed by ion implantation combined with pulsed-laser melting and incorporate Te-dopant concentrations several orders of magnitude above the solid solubility limit. With increasing Te concentration, the Te-hyperdoped layer changes from insulating to quasi-metallic behavior with a finite conductivity as the temperature tends to zero. The optical absorptance is found to increase monotonically with increasing Te concentration and extends well into the mid-infrared range. Temperature-dependent optoelectronic photoresponse unambiguously demonstrates that the extended infrared photoresponsivity from Te-hyperdoped Si p-n photodiodes is mediated by a Te intermediate band within the upper half of the Si band gap. This work contributes to pave the way toward establishing a Si-based broadband infrared photonic system operating at room temperature.


Publ.-Id: 27886

Tunnel magnetoresistance angular and bias dependence enabling tuneable wireless communication

Kowalska, E.; Fukushima, A.; Sluka, V.; Fowley, C.; Kákay, A.; Aleksandrov, Y.; Lindner, J.; Fassbender, J.; Yuasa, S.; Deac, A. M.

Spin-transfer torques (STTs) can be exploited in order to manipulate the magnetic moments of nanomagnets, thus allowing for new consumer-oriented devices to be designed. Of particular interest here are tuneable radio-frequency (RF) oscillators for wireless communication. Currently, the structure that maximizes the output power is an Fe/MgO/Fe-type magnetic tunnel junction (MTJ) with a fixed layer magnetized in the plane of the layers and a free layer magnetized perpendicular to the plane. This structure allows for most of the tunnel magnetoresistance (TMR) to be converted into output power. Here, we experimentally and theoretically demonstrate that the main mechanism sustaining steady-state precession in such structures is the angular dependence of the magnetoresistance. The TMR of such devices is known to exhibit a broken-linear dependence versus the applied bias. Our results show that the TMR bias dependence effectively quenches spin-transfer-driven precession and introduces a non-monotonic frequency dependence at high applied currents. Thus we expect the bias dependence of the TMR to have an even more dramatic effect in MTJs with Mn-Ga-based free layers, which could be used to design wireless oscillators extending towards the ‘THz gap’, but have been experimentally shown to exhibit a non-trivial TMR bias dependence.

Keywords: spin-torque nano-oscillator (STNO); MgO-based magnetic tunnel junction (MTJ); tunnel magnetoresistance (TMR); spin dynamics

Related publications

Publ.-Id: 27885

Hydrodynamic analysis in a viscous coupling using angle-resolved gamma-ray computed tomography

Bieberle, A.; Spies, A.; Schlottke, J.
ContactPerson: Bieberle, André; RightsHolder: Schlottke, Jan; Editor: Hampel, Uwe; Sponsor: Kühnel, Wolfram

This work comprises data provided by high-resolution gamma-ray computed tomography that was applied on a viscous coupling to visualize the internal operating fluid distribution. Therefore, angle-resolved time-averaged CT scanning technique was performed at different

  • cross-sectional positions,
  • rotational speeds as well as
  • at primary and secondary side. 

Keywords: viscous coupling; gamma-ray CT; process-synchronized fast imaging

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2018-09-05
    DOI: 10.14278/rodare.49


Publ.-Id: 27884

Activity-Based Probes for Tumour-Associated Transglutaminase 2: From Potent and Selective Inhibitors to Radiotracers

Löser, R.

The talk is covering the efforts of our group in the development of inhibitor-based radiotracers for the imaging of tumour-associated transglutaminase 2 (TGase 2). Major emphasis will be put on interesting structure-activity relationships of N6-acryloyllysine-derived inhibitors. In addition, general principles for targeting of TGase 2 by irreversible inhibitors will be highlighted. Labelling of these compounds with fluorine-18 and initial results towards their radiopharmacological evaluation will be presented.

  • Invited lecture (Conferences)
    Gordon Research Conference "Transglutaminases in Human Disease Processes", 17.-22.06.2018, Les Diablerets, Schweiz

Publ.-Id: 27883

Hysteresis Design of Magnetocaloric Materials—From Basic Mechanisms to Applications

Scheibel, F.; Gottschall, T.; Taubel, A.; Fries, M.; Skokov, K. P.; Terwey, A.; Keune, W.; Ollefs, K.; Wende, H.; Farle, M.; Acet, M.; Gutfleisch, O.; Gruner, M. E.

Magnetic refrigeration relies on a substantial entropy change in a magnetocaloric material when a magnetic field is applied. Such entropy changes are present at first-order magnetostructural transitions around a specific temperature at which the applied magnetic field induces a magnetostructural phase transition and causes a conventional or inverse magnetocaloric effect (MCE). First-order magnetostructural transitions show large effects, but involve transitional hysteresis, which is a loss source that hinders the reversibility of the adiabatic temperature change DTad. However, reversibility is required for the efficient operation of the heat pump. Thus, it is the mastering of that hysteresis that is the key challenge to advance magnetocaloric materials. We review the origin of the large MCE and of the hysteresis in the most promising first-order magnetocaloric materials such as Ni–Mn-based Heusler alloys, FeRh, La(FeSi)13-based compounds, Mn3GaC antiperovskites, and Fe2P compounds. We discuss the microscopic contributions of the entropy change, the magnetic interactions, the effect of hysteresis on the reversible MCE, and the size- and time-dependence of the MCE at magnetostructural transitions.

Publ.-Id: 27882

Dipeptide-derived Alkynes as Novel Irreversible Inhibitors of Cathepsin B

Behring, L.; Trapp, C.; Wodtke, R.; Kuhne, K.; Belter, B.; Steinbach, J.; Pietzsch, J.; Löser, R.

Until recently, alkynes were considered bioinert. Thus, they are popular reaction partners in bioorthogonal click reactions in vitro and in vivo. Despite the virtual chemical inertness of the alkyne moiety, two research groups observed the irreversible inhibition of a cysteine protease by an alkyne functionalised substrate derivative: both EKKEBUS et al. and SOMMER et al. independently described the unexpected inactivation of de-ubiquitinating enzymes by propargylated ubiquitin or ubiquitin-like modifiers bearing propargylamine in place of C-terminal glycine [1, 2]. We intended to harness that finding for the design of inhibitor-based probes for the imaging of tumour-associated cysteine proteases.
Cysteine cathepsins play an important role in tumour progression. In particular, cathepsin B is involved in a variety of tumour progression-related processes and an elevated extracellular levels are linked to increased malignancy and poor prognosis [3]. Therefore, this enzyme represents a promising target for the therapy and imaging of tumours.
GREENSPAN et al. reported a potent and highly selective, dipeptidyl nitrile-based cathepsin B inhibitor (N-[2-[(3-Carboxyphenyl)methoxy]-1(S)-cyanoethyl]-3-methyl-N2-(2,4-difluorobenzoyl)-L-phenylalaninamide) [4]. Based on that lead compound, cathepsin B-targeting dipeptide alkynes were designed by isoelectronic replacement of the nitrile nitrogen atom by by a methine group and consecutive variation of the 2,4-difluorobenzoyl and (3-carboxybenzyl)oxymethyl residue. Formation of the C-C triple bond by reaction of the corresponding open-chain serine-derived aldehyde with the Bestmann-Ohira reagent was accompanied by partial enantiomerisation. Therefore, the synthesis was performed via Garner’s aldehyde, which accounted for high stereochemical purity of the final compounds. The inhibitory potential was investigated against cathepsins B, S, L and K. The most potent compound exhibited irreversible inhibition of cathepsin B with an inactivation constant (kinact/KI=771 M-1s-1). Values for cathepsins L, S and K were significantly lower; no irreverisible ihibition was observed for cathepsin K. In addition, inhibition of cathepsin B activity in human glioblastoma cell lysates and living cells has been demonstrated. Based on these promising results, dipeptidyl alkynes have the potential to become a valuable tool for imaging due to the expected low activity towards other cysteine proteases. In further studies, selected inhibitors for cathepsin B will be labelled with suitable radionuclides to obtain an inhibitor-based probe directed towards cathepsin B.

[1] Ekkebus et al., J. Am. Chem. Soc., 2013, 135, 2867-2870
[2] Sommer et al., Bioorg. Med. Chem., 2013, 21, 2511-2517
[3] Löser and Pietzsch, Front. Chem., 2015, 3:37
[4] Greenspan et al., J. Med. Chem., 2001, 44, 4524-4534.

  • Lecture (Conference)
    35th European Peptide Symposium, 26.-31.08.2018, Dublin, Irland
  • Open Access Logo Abstract in refereed journal
    Journal of Peptide Science 24(2018)S2, OP64
    DOI: 10.1002/psc.3127
  • Contribution to proceedings
    35th European Peptide Symposium, 26.-31.08.2018, Dublin, Ireland
    Proceedings of the 35th European Peptide Symposium: European Peptide Society, 64-66
    DOI: 10.17952/35EPS.2018.064

Publ.-Id: 27881

Methyl selenol as precursor in selenite reduction to Se/S species by methane-oxidizing bacteria

Eswayaha, A. S.; Hondow, N.; Scheinost, A. C.; Merroun, M.; Romero-Gonzalez, M.; Smith, T. J.; Gardiner, P. H. E.

In this study, we demonstrate for the first time that in the reduction of selenite by Mc. capsulatus (Bath), a methane oxidizing bacterium, methyl selenol is the precursor for the formation of methylated selenium-containing and mixed chalcogenides species. Subsequent exchange reactions between the species result in the formation of the amorphous allotropic form of selenium, which is cyclic Se8 with sulfur in its structure.

Keywords: selenol; methane reducing bacteria; Mc. capsulatus; XPS; XAFS; FTIR; TEM; Raman; Selenium

  • Open Access Logo Applied and Environmental Microbiology 85(2019)22, e01379-19
    Online First (2019) DOI: 10.1128/aem.01379-19


Publ.-Id: 27880

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]