Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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32228 Publications
Morphological and Functional Modifications of Optical Thin Films for Space Applications Irradiated with Low-Energy Helium Ions
Pelizzo, M. G.; Corso, A. J.; Tessarolo, E.; Böttger, R.; Hübner, R.; Napolitani, E.; Bazzan, M.; Rancan, M.; Armelao, L.; Jark, W.; Eichert, D.; Martucci, A.;
Future space missions will operate in increasingly hostile environments, such as those in low-perihelion solar orbits and Jovian magnetosphere. This exploration involves the selection of optical materials and components resistant to the environmental agents. The conditions in space are reproduced on ground through the use of ion accelerators. The effects of He particles coming from the solar wind impinging on a gold thin film have been systematically investigated, considering absorbed doses compatible with the duration of the European Space Agency Solar Orbiter mission. Structural and morphological changes have been proved to be dependent not only on the dose but also on the irradiation flux. A predictive model of the variation of thin film reflectance has been developed for the case of lower flux irradiation. The results are discussed regarding reliability and limitations of laboratory testing. The outcomes are important to address the procedures for the space qualification tests of optical coatings.
Keywords: optical thin films, gold coatings, ion irradiation, helium ions, space weather

Publ.-Id: 28038 - Permalink


Competing risks in survival data analysis
Dutz, A.; Löck, S.;
Clinical trials and retrospective studies in the field of radiation oncology often consider time-to-event data as their primary endpoint. Such studies are susceptible to competing risks, i.e. competing events may preclude the occurrence of the event of interest or modify the chance that the primary endpoint occurs. Competing risks are frequently neglected and the event of interest is analysed with standard statistical methods. Here, we would like to create awareness of the problem and demonstrate different methods for survival data analysis in the presence of competing risks.
Keywords: Competing risk, Survival data, Time-to-event data, Cox regression

Publ.-Id: 28036 - Permalink


Alkyl Branching Position in Diketopyrrolopyrrole Polymers: Interplay between Fibrillar Morphology and Crystallinity and Their Effect on Photogeneration and Recombination in Bulk-Heterojunction Solar Cells
Shivhare, R.; Erdmann, T.; Hörmann, U.; Collado-Fregoso, E.; Zeiske, S.; Benduhn, J.; Ullbrich, S.; Hübner, R.; Hambsch, M.; Kiriy, A.; Voit, B.; Neher, D.; Vandewal, K.; Mannsfeld, S. C. B.;
Diketopyrrolopyrrole (DPP)-based donor-acceptor copolymers have gained a significant amount of research interest in the organic electronics community because of their high charge carrier mobilities in organic field-effect transistors (OFETs) and their ability to harvest near-infrared (NIR) photons in solar cells. In this study, we have synthesized four DPP-based donor-acceptor copolymers with variations in the donor unit and the branching point of the solubilizing alkyl chains (at the second or sixth carbon position). Grazing incidence wide-angle X-ray scattering (GIWAXS) results suggest that moving the branching point further away from the polymer backbone increases the tendency for aggregation and yields polymer phases with a higher degree of crystallinity (DoC). The polymers were blended with PC70BM and used as active layers in solar cells. A careful analysis of the energetics of the neat polymer and blend films reveals that the charge-transfer state energy (ECT) of the blend films lies exceptionally close to the singlet energy of the donor (ED*), indicating near zero electron transfer losses. The difference between the optical gap and open-circuit voltage (VOC) is therefore determined to be due to rather high nonradiative (≈ 418 ± 13 mV) and unavoidable radiative voltage losses (≈ 255 ± 8 mV). Even though the four materials have similar optical gaps, the short-circuit current density (JSC) covers a vast span from 7 to 18 mA cm-2 for the best performing system. Using photoluminescence (PL) quenching and transient charge extraction techniques, we quantify geminate and nongeminate losses and find that fewer excitons reach the donor-acceptor interface in polymers with further away branching points due to larger aggregate sizes. In these material systems, the photogeneration is therefore mainly limited by exciton harvesting efficiency.

Publ.-Id: 28035 - Permalink


Dezentrale Produktion werthaltiger Kohlenwasserstoffe mit Hilfe lastflexibler, integrierter Elektrolyse-Synthese-Apparate
Schwarze, L.; Fogel, S.; Schwabe, F.; Partmann, C.; Lippmann, W.; Kryk, H.; Hurtado, A.; Hampel, U.;
Der stetige Ausbau von Wind- und Solarenergie in Deutschland erfordert effiziente Technologien zur räumlich-zeitlichen Flexibilisierung des Energieversorgungssystems. Infolge der Netzeinbindung fluktuierender Energien ergeben sich grundlegend neue Anforderungen an die bestehende, grundlastbasierte Energiewirtschaft und deren Infrastruktur. Technologien zur direkten Speicherung von Elektroenergie in relevanten Größenordnungen scheitern derzeit aus verschiedenen Gründen, bspw. der Standort-Limitierung von Pumpspeicherkraftwerken oder der Kostenineffizienz von Batterien. Im Rahmen des Verbundforschungsvorhabens „DELTA“ (EF-RE-Förderkennzeichen: 100240618) wird ein frei skalierbarer, dezentral einsetzbarer, modular aufgebauter, wirtschaftlich attraktiver und technisch flexibler Demonstrator zur chemischen Langzeitspeicherung von Elektroenergie (Power-to-Liquid) entwickelt und erprobt. Strom wird einem tubularen, protonenleitenden Dampf-Elektrolyseur zur Erzeugung von hochreinem Wasserstoff zugeführt. Dieser wird direkt unter stofflicher Verwertung von CO2 einer integrierten, heterogen katalysierten Methanolsynthese unterzogen. Durch die Kopplung stationärer CO2-Emittenten und -Verbraucher wird CO2 in einem geschlossenen Kreislauf nutzbar. Flüssige Kohlenwasserstoffe finden sektorübergreifend sowohl als synthetische Kraftstoffe als auch als Grundstoffe für weitere chemische Produkte oder zur Rückverstromung Verwendung und stellen somit eine interessante Wertschöpfungsalternative innerhalb der Chemie- und Energiewirtschaft dar. Die hohe Systemintegration innerhalb des Demonstrators ermöglicht eine energetisch optimierte Prozessführung sowie ein effizientes Energie- und Stoffstrom-Management, weshalb sich das Reaktorsystem durch geringe Energieverluste, hohe Systemwirkungsgrade, Kosteneffizienz und eine hohe Zuverlässigkeit sowie Lastwechselfähigkeit auszeichnet. Der Demonstrator stellt in einer späteren technischen Anwendung ein Basismodul dar, welches mit weiteren Modulen zu einer flexiblen Gesamtanlage verschaltet werden kann. Im Rahmen der Präsentation soll das grundlegende Anlagenkonzept sowie die ersten Ergebnisse des Basic Engineerings und der rechnergestützten Modellierung und Simulation vorgestellt werden.
Keywords: Elektrolyse, Methanolsynthese, Power-to-X, Lastflexibel, Energiespeicher
  • Lecture (Conference)
    Jahrestreffen der ProcessNet-Fachgruppe Energieverfahrenstechnik, 07.-08.03.2018, Frankfurt am Main, Deutschland

Publ.-Id: 28034 - Permalink


Simulation des dynamischen Betriebsverhaltens eines gekoppelten Elektrolyse-Synthese-Prozesses für lastflexible Anwendungen
Schöne, C.;
Im Rahmen der Bachelorarbeit wurde der aktuelle Stand von Wissenschaft und Technik für die Modellierung und Simulation des dynamischen Verhaltens von Hochtemperaturelektrolyseuren sowie für die Synthese von Methanol durch direkte Hydrierung von Kohlenstoffdioxid dargestellt. Aufbauend auf einem 0D-Prozessmodell für die Kopplung einer protonenleitenden Hochtemperaturelektrolysezelle (H-SOEC) mit einer Methanolsynthese wurde das grundlegende stationäre Betriebsverhalten beschrieben und mit Literaturdaten verglichen. Außerdem wurde das dynamische Betriebsverhalten des Gesamtprozesses im Falle von transienten Lastprofilen (Teil-/Volllastsprünge und fluktuierende Profile), verschiedenen Betriebsmodi (An- und Abfahrprozesse) und transienten Randbedingungen charakterisiert sowie wesentliche Strategien zur Steuerung und Regelung abgeleitet.
Keywords: Modellierung und Simulation, Prozessdynamik, Dynamisches Verhalten, Steuerung und Regelung
  • Bachelor thesis
    TU Dresden, 2018
    Mentor: Stefan Fogel, Holger Kryk
    70 Seiten

Publ.-Id: 28033 - Permalink


Bestimmung des stationären und dynamischen Betriebsverhaltens einer gekoppelten Elektrolyse-Synthese-Stufe mittels 2D-FEM-Simulationen
Knitt, F.;
Im Rahmen der Diplomarbeit wurde der aktuelle Stand von Wissenschaft und Technik für die Synthese von Methanol durch direkte Hydrierung von Kohlenstoffdioxid, deren Modellierung und Simulation sowie für das dynamische Verhalten von Hochtemperaturelektrolyseuren dargestellt. Aufbauend auf einer zu ermittelnden Reaktionskinetik wurde ein Modell für die beschriebene Methanolsynthese erstellt und mit vorgegebenen Betriebsparametern simuliert sowie mit Literaturdaten verglichen. Anschließend wurde das Synthesemodell mit einem bereits vorhandenen Modell eines protonenleitenden Hochtemperaturelektrolyseurs (H-SOEC) kombiniert. Mit Hilfe der Modellkombination konnten wesentliche Betriebsparameter (Mengenströme, Produktzusammensetzungen, Temperaturen, etc.) und Betriebslimitationen für einen räumlich eng gekoppelten Betrieb von Elektrolyse und Synthese bestimmt werden.
Keywords: Modellierung, Simulation, SOEC, Methanolsynthese, Dynamisches Verhalten
  • Diploma thesis
    TU Dresden, 2018
    Mentor: Stefan Fogel, Holger Kryk
    94 Seiten

Publ.-Id: 28032 - Permalink


Development and evaluation of a 99mTc(III) ‘4 + 1’ complex derived from estradiol for imaging breast cancer
Tejería, E.; Pietzsch, H.-J.; Giglio, J.; Rey, A.;
Estrogen receptors are overexpressed in about 70% of breast cancer and identification of their presence is important to select the appropriate treatment and evaluate the response.
With this objective, an estradiol derivative (L) 5-((1-carboxy-2-(4-((13S,17S)-3,17-dihydroxy-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthren-17-yl)-1H-1,2,3-triazol-1-yl)ethyl)amino)-N-methylidyne-5-oxopentan-1-aminium, was used to develop a ‘4+1’ complex of Tc(III) for estrogen receptor imaging.
The synthesis of L involved the coupling of the amino group of 3-azido-L-alanine with an activated isonitrile, to then perform a "click chemistry" reaction with the ethinyl group of ethinylestradiol.
Labelling was carried out in two stages, preparation of the precursor [99mTc]Tc-EDTA, using mannitol, EDTA and SnCl2 as reducing agent and simultaneous substitution (30 min at 75°C) with L (20 mg) and the tetradentate coligand 2-[Bis(2-mercaptoethyl)amino]ethanethiol (NS3) (2 mg). The HPLC analysis showed a major peak (tr=13 min). The radiochemical purity of the HPLC purified complex was greater than 95%.
The lipophilicity expressed as logP (partition coefficient between octanol and phosphate buffer 0.1M, pH = 7.4) was 0.48±0.06. The plasma protein binding was (46 ± 6) % at 60 minutes. The complex was stable in the labelling milieu and in human serum for at least 4 hours. Cell uptake in MCF7 cells are in progress.
A potential radiopharmaceutical derived from estradiol was obtained with high radiochemical purity. The complex presents adequate stability and physicochemical properties. In vitro and in vivo studies including nude mice bearing xenografted breast tumors will be used to validate the clinical potentiality.
  • Lecture (Conference)
    TeraChen 2018, 26.-29.09.2018, Brixen, Italien

Publ.-Id: 28031 - Permalink


Cross-bridged cyclams with bis(phosphinic acid) pendants for a fast Cu(II) complexation: towards efficient 64-Cu labeling
Kubíček, V.; David, T.; Lubal, P.; Pietzsch, H.-J.; Hermanna, P.;
Copper radioisotopes chelators are commonly based on macrocycles but they mostly suffer from in vivo instability, slow (not efficient) radiolabeling and low selectivity over competing ions. Cyclam derivatives offer high selectivity for Cu(II). Complexes of cross-bridged (CB-) cyclams are very stable in-vivo, however, their radiolabelling is not efficient.
We have found that bis(phosphinic acid) pendant arm (BPi) highly accelerate Cu(II) complexation.[1] It was also found, on Me3cyclam derivatives as model ligands, that phosphonic acid (Po) and bis(phosphorus acid) pendant arms are the most suitable ones for fast chelation.[2]
Chelators with BPi-like pendants on CB-cyclam (cb-BPC) were synthesized. Their complexation properties (structure, thermodynamics, formation/decomplexation kinetics) were investigated and analogous data were also obtained for known phosphorus chelators as cb-TE2P. All ligands are basic (last pKa>13.5) and form thermodynamically stable copper complexes. Other metal ion complexes are hardly formed in water. The Cu(II) complexes are formed quickly with some dependence on a kind of the pendant arms. Complexes of BPi containing chelators are significantly less kinetically inert than those of cb-TE2P but still much more inert than complexes of most of common chelators as DOTA. The phosphonic acid and BPi on CB-cyclams exhibit fast radiolabeling with 64-Cu even at room temperature and the labelled chelators are obtained with a high specific activity. These radiolabelling properties are not altered after conjugations.[3] The ligands can be suggested as a new chelator family for copper radioisotopes.
  • Poster
    TeraChem 2018, 26.-29.09.2018, Brixen, Italien

Publ.-Id: 28030 - Permalink


Bifunctional cyclam derivatives with a bis(phosphinate) pendant arm as efficient chelators for copper radionuclides
David, T.; Hlinová, V.; Kubíček, V.; Bergmann, R.; Pietzsch, H.-J.; Hermann, P.;
Bifunctional cyclam derivatives with one bis(phosphinic acid) pendant arm bearing carboxylate, amine, isothiocyanate, azide or cyclooctyne functions in the pendant arm side chain were synthesized (Figure). The bifunctional groups were introduced far from the metal-binding site, either by using newly synthesized bis(phosphinic acid) precursors or by modifying the reactive groups. Direct coupling without protecting the pendant phosphinate or ring secondary amine groups was feasible. The ligands were successfully conjugated to model compounds including oligopeptides, biotin or fluorescent dye.
Labeling of the bifunctional ligands with 64Cu showed very high radiolabeling efficiency, leading to a significantly higher molar activity than that described for other commonly used macrocyclic chelators. It confirms that using properly designed phosphinic acid pendant arm(s) is a good strategy to achieve conjugation flexibility (due to the distant bifunctional site) without compromising the radiolabeling efficiency or the high specific activity of radiopharmaceuticals.
A prototypic representative was evaluated in-vivo by metabolite analysis, biodistribution studies and PET scans. The data clearly showed the very high metabolic stability of the 64Cu chelate unit as no decomplexation was detected. Except for the excretory organs, no prominent uptake and retention was observed.
Thus, bis(phosphinate)-bearing cyclam-based ligands are highly promising radiocopper chelators for conjugation to targeting units, such as peptides, oligonucleotides or antibodies and their fragments.
  • Poster
    TeraChem 2018, 26.-29.09.2018, Brixen, Italien

Publ.-Id: 28029 - Permalink


Water-saving strategies in the mining industry – the potential of mineral processing simulators as a tool for their implementation
Michaux, B.; Hannula, J.; Rudolph, M.; Reuter, M. A.; van den Boogaart, K. G.; Möckel, R.; Kobylin, P.; Hultgren, M.; Peltomäki, M.; Roine, A.; Remes, A.;
As the mining industry is facing an increasing number of issues related to its fresh water consumption, water-saving strategies are progressively being implemented in the mineral processing plants, often leading to variations in the process water chemistry. However, the impact of water chemistry variations on the process performance is rarely known beforehand, thus creating an obstacle to the implementation of those water-saving strategies. To tackle this problem, the effect the different dissolved species present in the process water have on the processing plant performance must be quantified, and this information must be digitalized in a practical and suitable form to be used in mineral processing simulators. To achieve this goal, a methodology to digitalize the influence of the process water composition on the flotation performance is presented in this paper. Using the flotation of a fluorite ore as case study, the relationship between process water composition and the flotation kinetics of that fluorite ore was determined. This relationship was digitalized in HSC Sim, a mineral processing simulator, turning it into a tool capable of simulating the flotation performance under a variety of process water compositions. Finally, the potential of this new tool to help implementing water-saving strategies on the mine site is discussed, and the challenges that need to be overcome in order to apply this tool at industrial scale are being addressed.
Keywords: Water-saving strategies, Water chemistry, Flotation kinetics, Simulation-based optimization.

Downloads:

  • Secondary publication expected from 15.03.2020

Publ.-Id: 28027 - Permalink


Ligand development for the Radiometal Hg-197(m)
Gilpin, M.; Walther, M.; Pietzsch, H.-J.; Steinbach, J.;
Reactor-produced Hg-197 had previous medical use for imaging[1] but was discontinued due to low stability and low specific-activity. Cyclotron-produced Hg-197(m) can overcome the toxicity problem, due to much higher molar activity[2], allowing access to the radiometal’s useful decay modes (γ for SPECT-imaging. Conversion & auger electrons for therapy) at sub-toxic Hg-concentrations.
Development in Hg ligands for medicinal applications necessitates stability in vivo but the poor long-term stability of Mercury compounds in solution is an ongoing issue[3]. Hg-organometallics show good water-stability and bypass the issue of Hg-S bonds suffering from competition by common biomolecules, e.g. cysteine. Therefore, our focus is on Hg-C chemistry, specifically the strongest bond kind: the mercury-phenyl bond[4].
As prior research has shown that the synthetically simpler route of monodentate ligands (κ1-L2Hg) suffers from significant cleavage[5], this research is centred on the syntheses of bidentate chelators benefitting from entropic stability. Purification of the Hg-197(m) leaves it in an acidic aqueous medium as the chloride salt, thus transmetallation, via stannyl or boronic acid derivatives, was chosen as a viable option for mercury attachment. Chelator designs began with a dibenzylisophthalamide template but low selectivity for the 1:1-compound encouraged a better fitting structure. Recent radio-labelling experiments show promise for specific binding with a design based on the bispidine backbone (attractive for being known in co-ordination chemistry for a variety of metals[6] and possessing bridge linking-functionalisation).
Analyses are performed through radio-TLC and HPLC, whilst stable mercury compound analysis includes Hg-199 NMR.

References :
(1) Sodee. J. Nucl. Med. 1968; 9: 645.
(2) Walther et al. Appl. Radiat. Isot. 2015; 97: 177–181.
(3) Henke et al. Wat. Res. 2000; 34: 3005-3013.
(4) Dean. Lange’s Handbook of Chemistry, 15th ed.; McGraw-Hill Inc, 1998; 606.
(5) Wilhelm. et al. Z. Naturforsch. 2000; 55b: 35–38.
(6) Comba et al. Inorg. Chem. 2009; 48: 6604–6614.
Keywords: Mercury 197, Chelator, Ligand, Radiometal, Bispidine, Cancer, Theragnostics
  • Poster
    TERACHEM 2018, 24.-29.09.2018, Bressanone, Italy

Publ.-Id: 28026 - Permalink


Development and characterization of a 177Lu-labeled anti-prostate stem cell antigen (PSCA) monoclonal antibody for metastatic prostate cancer
Striese, F.; Bergmann, R.; Bachmann, M.; Arndt, C.; Feldmann, A.; Weißflog, S.; Steinbach, J.; Pietzsch, H.;
The clinical need of new therapeutics for advanced prostate cancer is continuingly high because there still exist no curative treatment options. It has been shown that especially targeted therapies using radionuclides gives enhanced specificity and increased overall survival of prostate cancer patients. Antibodies represent attractive transport vehicles for the delivery of radionuclides to prostate cancer cells for several reasons, such as: metastatic site location and small volume disease. Here, we describe the development and characterization of a novel 177Lu-labeled antibody-conjugate that offers encouraging features to be used for the therapy PSCA-expressing prostate tumors. The PSCA is a cell surface antigen that is present in nearly all primary prostate tumors and further upregulated in many bone and lymph node metastases. Therefore, it is proposed as a promising tumor target structure for both, therapy and diagnosis, of prostate cancer. Purified PSCA-directed antibody demonstrated a high specificity and affinity, with dissociation constant of 10 nM to PC3-PSCA cells. The antibody was conjugated with, on average, three CHX-A’’-DTPA molecules, as verified by MALDI-TOF analysis. Subsequent radiolabeling of the antibody-chelator-conjugate with Lutetium-177 could be performed at high radiochemical purity (>95%, radio HPLC) while preserving binding properties to the PSCA. SPECT scanning with the 177Lu-labeled antibody-conjugate was used to investigate the targeting potential in mice with established PSCA-expressing tumors. The outcome was the production of excellent high contrast images from 3 to 170 h post injection. With these promising results, we next want to evaluate the antitumor activity in vivo.
Keywords: prostate cancer, metastatic, Prostate Stem Cell Antigen (PSCA), radiolabeled monoclonal antibody, Lu-177, theragnostics
  • Lecture (Conference)
    TERACHEM 2018, 26.-29.09.2018, Bressanone, Italy

Publ.-Id: 28025 - Permalink


Evaluation of [Tc-99m]Tc-tricarbonyl labeled alpha-melanocyte stimulating hormone derived peptide conjugates for melanoma imaging
Gao, F.; Sihver, W.; Bergmann, R.; Weißflog, S.; Bolzati, C.; Salvarese, N.; Belter, B.; Steinbach, J.; Pietzsch, J.; Pietzsch, H.;
The melanocortin 1 receptor (MC1R), since overexpressed in melanoma cells, is an attractive target for imaging or treatment of this type of malignancies. The α-melanocyte stimulating hormone (α-MSH) derived peptide NAP-NS1 (Nle-Asp-His-D-Phe-Arg-Trp-Gly-NH2) binds with high affinity [1] and was engineered in three different ways for labeling with [Tc-99m]Tc-tricarbonyl. ɛ-Ahx-β-Ala-NAP-NS1, ethylenglycol (EG)-based linker NAP-NS1 and NAP-NS1 without linker were conjugated with bis(pyridin-2-ylmethyl)amine (DPA) obtaining yields of 42%, 38% and 45%, respectively. For standard purpose non-radioactive Re-DPA-peptides were prepared [2] with yields > 55%. The labeling with a one-pot method was faster than with a two steps method, and even receiving slightly higher radiochemical yields. High stability as well as negligible transschelation was observed for the [Tc-99m]Tc-tricarbonyl-peptide conjugates. The ethylenglycol based linker increased the hydrophilicity. Binding results, first of competition assays with the non-radioactive α-MSH conjugates, and second of saturation assays with the [Tc-99m]Tc-tricarbonyl-DPA peptides resulted in high affinity (low nanomolar range) where the labeled peptides showed a marginal loss of affinity; that was relevant for murine B16F10, as well as for human MeWo and TXM13 cells. The number of binding sites was considerably higher in murine melanoma cells. The three [Tc-99m]Tc-tricarbonyl-peptide conjugates exhibited similar in vitro properties. Preliminary in vivo studies were performed with [Tc-99m]Tc-tricarbonyl-DPA-ɛ-Ahx-β-Ala-NAP-NS1 in rats and showed good metabolic stability in blood and both a renal and hepatobiliary excretion. Hence, it displayed prospective radiochemical and radiopharmacological properties, suggesting a promising candidate for further investigation in a melanoma xenograft model.

[1] Gao et al. J. Amino Acids 2016; 48: 833-847.
[2] Alberto et al. J. Chem. Soc. Dalton 1994; 19: 2815-2820.
Keywords: Melanocortin-1 receptor, α-MSH analogs, Tc-99m labeling, Malignant melanoma
  • Poster
    TERACHEM 2018, 26.-29.09.2018, Bressanone, Italy

Publ.-Id: 28024 - Permalink


Dynamic Imaging of the Delay-and Tilt-Free Motion of Neel Domain Walls in Perpendicularly Magnetized Superlattices
Finizio, S.; Wintz, S.; Zeissler, K.; Sadovnikov, A. V.; Mayr, S.; Nikitov, S. A.; Marrows, C. H.; Raabe, J.;
We report on the time-resolved investigation of current- and field-induced domain wall motion in perpendicularly magnetized microwires exhibiting asymmetric exchange interaction by means of scanning transmission x-ray microscopy using a time step of 200 ps. Dynamical domain wall velocities on the order of 50-100 m s−1 were observed. The improvement in the temporal resolution allowed us to observe the absence of incubation times for the motion of the domain wall, together with indications for a negligible inertia. Furthermore, we observed that, for short current and magnetic field pulses, the magnetic domain walls do not exhibit a tilting during its motion, providing a mechanism for the fast, tilt-free, motion of magnetic domain walls.
Keywords: domain wall motion, x-ray microscopy, spin-orbit torques

Publ.-Id: 28022 - Permalink


Impact of Haloarchaea on speciation of uranium – a multi-spectroscopic approach
Bader, M.; Rossberg, A.; Steudtner, R.; Drobot, B.; Großmann, K.; Schmidt, M.; Musat, N.; Stumpf, T.; Ikeda-Ohno, A.; Cherkouk, A.;
Haloarchaea represent a predominant part of the microbial community in rock salt, which can serve as host rock for the disposal of high level radioactive waste. However, knowledge is missing about how Haloarchaea interact with radionuclides. Here, we used a combination of spectroscopic and microscopic methods to study the interactions of an extremely halophilic archaeon with uranium, one of the major radionuclides in high level radioactive waste, on a molecular level. The obtained results show that Halobacterium noricense DSM 15987T influences uranium speciation as a function of uranium concentration and incubation time. X-ray absorption spectroscopy reveals the formation of U(VI) phosphate minerals, such as meta-autunite, as the major species at a lower uranium concentration of 30 µM, while U(VI) is mostly associated with carboxylate groups of the cell wall and extracellular polymeric substances at a higher uranium concentration of 85 µM. For the first time, we identified uranium biomineralization in the presence of Halobacterium noricense DSM 15987T cells. These findings highlight the potential importance of Archaea in geochemical cycling of uranium and their role in biomineralization in hypersaline environments, offering new insights into the microbe-actinide interactions in highly saline conditions relevant to the disposal of highly radioactive waste as well as bioremediation.

Publ.-Id: 28021 - Permalink


1,4,7-Triazacyclononane: An effective chelator for copper-64
Kubeil, M.ORC; Pant, K.; Joshi, T.; Stephan, H.
1,4,7-Triazacyclononane (TACN) is a versatile platform from which various ligands can be derived to form effective chelators for (radio)copper(II) complexation. [1] The ability of TACN-derivatives to form highly stable complexes with copper(II) is greatly influenced by the number and type of substituents on the macrocyclic ring. The formed copper(II) complexes show a broad variability in their thermodynamic stability and kinetic inertness, varying in structure from square-pyramidal to distorted octahedral. TACN-based BFCAs have also been used for indirect radiolabelling of biomolecules, rendering them suitable for imaging and therapy.
Herein, examples of various copper-64 TACN complexes will be presented which provide a picture of how different substituents influence the coordination mode, electronic properties and in vivo stability of. By applying principles of coordination chemistry, it is possible to tune the affinity of TACN-based ligands for copper ligation, as well as their availability for subsequent biomolecular functionalisation. Target-specific TACN based conjugates (peptides, antibody fragments) and bio(nano)materials labelled with copper-64 enabling tumour imaging and biodistribution studies via positron emission tomography will be discussed as well. [2, 3, 4]

[1] T. Joshi et al. ChemPlusChem 2018; DOI: 10.100 2/cplu.201800103.
[2] K. Pant et al. Bioconjugate Chem. 2015; 26: 906-918.
[3] K. Viehweger et al. Bioconjugate Chem. 2014; 25: 1011-1022.
[4] R. Bergmann et al. Sci. Rep. 2017; 7.
Keywords: TACN, copper-64, chelator
  • Poster
    The third International Symposium on Technetium and Other Radiometals in Chemistry and Medicine, 26.-29.09.2018, Brixen, Bressanone, Italia

Publ.-Id: 28020 - Permalink


Carbon doping controlled thermoluminescent defect centers in nanoporous alumina for ion beam dosimetry
Bhowmick, S.; Pal, S.; Das, D.; Singh, V. K.; Khan, S. A.; Hübner, R.; Barman, S. R.; Kanjilal, D.; Kanjilal, A.;
The flexibility of amorphous anodized alumina (AAO) in developing radiation dosimeter for hadron therapy is reported by controlled carbon ion implantation, followed by thermoluminescence (TL) measurements. The efficacy of amorphous AAO in controlling TL sensitivity is found to be governed by an increase in F+ defect centers as a function of carbon concentration, as revealed from the close resemblance of the trend in photoluminescence intensity. Moreover, its nanoporous structure is demonstrated to be advantageous for defect engineering due to the increase in the surface-to-volume ratio. Detailed X-ray photoelectron spectroscopy analysis suggests the formation of F+ centers by substituting Al3+ ions with C2+ in the vicinity of oxygen vacancies, where depth-dependent study showed the evolution of conducting channels owing to sp2 hybridized C–C bonding, leading to a differential charging effect. This work provides a direction to tune nanoporous AAO in its amorphous form for future ion beam dosimetry.

Publ.-Id: 28018 - Permalink


GitLab-Runner fork
Frust, T.;
This is a fork of the official gitlab-runner repository at https://gitlab.com/gitlab-org/gitlab-runner and is used to generate binaries and the helper image for the Power architecture (ppc64le), since this architecture is not officially supported by GitLab itself.
  • Software in external data repository
    Publication year 2018
    Programming language: Go
    System requirements: Power architecture (ppc64le)
    License: MIT (Link to license text)
    Hosted on HZDR GitLab: Link to location

Publ.-Id: 28017 - Permalink


Improved Conjugation, 64-Cu Radiolabeling, in Vivo Stability, and Imaging Using Nonprotected Bifunctional Macrocyclic Ligands: Bis(Phosphinate) Cyclam (BPC) Chelators
David, T.; Hlinová, V.; Kubíček, V.; Bergmann, R.; Striese, F.; Berndt, N.; Szöllösi, D.; Hegedus, N.; Mathe, D.; Bachmann, M.; Pietzsch, H.-J.; Hermann, P.;
Bifunctional derivatives of bis(phosphinate)-bearing cyclam (BPC) chelators bearing a carboxylate, amine, isothiocyanate, azide, or cyclooctyne in the BP side chain were synthesized. Conjugations required no protection of phosphinate or ring secondary amine groups. The ring amines were not reactive (proton protected) at pH < ∼8. For isothiocyanate coupling, oligopeptide N-terminal α-amines were more suitable than alkyl amines, e.g., Lys ω-amine (pKa ∼7.5−8.5 and ∼10−11, respectively) due to lower basicity.
The Cu-64 labeling was efficient at room temperature (specific activity ∼100 GBq/μmol; 25 °C, pH 6.2, ∼100 ligand equiv, 10 min). A representative Cu-64-BPC was tested in vivo showing fast clearance and no nonspecific radioactivity deposition. The monoclonal anti-PSCA antibody 7F5 conjugates with thiocyanate BPC derivative or NODAGA were radiolabeled and studied in PC3-PSCA tumor bearing mice by PET. The radiolabeled BPC conjugate was accumulated in the prostate tumor with a low off-target uptake, unlike Cu-64-labeled NODAGA−antibody conjugate. The BPC chelators have a great potential for theranostic applications of the Cu-64/Cu-67 matched pair.

Publ.-Id: 28015 - Permalink


Progress on High Peak Current Laser Wakefield Electron Acceleration
Schramm, U.ORC
Report on the generation of multi 10 kA electron bunches with LWFA and related applications.
  • Invited lecture (Conferences)
    60th ICFA Advanced Beam Dynamics Workshop on Future Light Sources (FLS2018), 05.-09.03.2018, Shanghai, China

Publ.-Id: 28014 - Permalink


From plasma acceleration to accelerators ?
Schramm, U.ORC
Status of PW laser experiments
  • Invited lecture (Conferences)
    OPIC OPTICS & PHOTONICS International Congress, 23.-26.04.2018, Pacifico Yokohama, Japan
  • Invited lecture (Conferences)
    Freitagsseminar IAP-Frankfurt, 22.06.2018, Frankfurt, Deutschland
  • Invited lecture (Conferences)
    HICforFAIR-Kolloquium Giessen, 21.06.2018, Giessen, Deutschland

Publ.-Id: 28013 - Permalink


Accelerator mass spectrometry (AMS) for beryllium-7 measurements in smallest rainwater samples
Tiessen, C.; Bemmerer, D.; Rugel, G.; Querfeld, R.; Scharf, A.; Steinhauser, G.; Merchel, S.ORC
Beryllium-7, mainly measured via γ-spectrometry, is used as a (natural) radiotracer for education and science. For lower activities (<0.1 Bq) and samples containing also longer-lived ¹⁰Be, accelerator mass spectrometry (AMS) is the method-of-choice. We demonstrate that ⁷Be- and ¹⁰Be can be quantified at the Dresden AMS facility on the same prepared BeO. Detection limits (⁷Be) are ~0.6 mBq. Samples as small as tens of millilitre of rainwater can be chemically processed (after acidification) within a few hours without expensive and slow ion exchange. Isobar (⁷Li) suppression by chemistry and AMS is sufficient to guarantee for an ultrasensitive, cheap, and fast detection method for ⁷Be allowing high sample throughput.
Keywords: ⁷Be, ¹⁰Be, accelerator mass spectrometry, AMS, rain

Publ.-Id: 28012 - Permalink


Stability and Electronic Properties of Palladium Dichalcogenide Polytypes as Nanomaterials
Kempt, R.; Kuc, A.; Heine, T.;
We present a detailed computational investigation of the stability and electronic properties of three different polytypes of the palladium dichalcogenides PdX2. These are intriguing for electronic and optical applications as nanomaterials, including logical junctions because of a potential metal-semiconductor transition in the 1T polytype when going from bulk to monolayers.[1,2]
Both PdS2 and PdSe2 crystallize in a layered pyrite-type structure or 2O (see Fig. 1) as bulk materials.[3] Only for high pressures, they adopt the cubic pyrite-type structure.[4] Recently, monolayers of PdSe2 have been exfoliated and shown to maintain their pentagonal structure found in the bulk material.[5] In contrast to PdS2 and PdSe2, bulk PdTe2 occurs naturally in 1T.[6]
We evaluate the differences in chemical bonding between the possible polytypes by density functional theory and show that it requires a hybrid approach in order to properly account for the electron correlation effects in these systems. From there, we estimate their electronic properties and stabilities as nanomaterials.
  • Lecture (Conference)
    Flatlands Beyond Graphene 2018, 03.-07.09.2018, Universität Leipzig, Germany

Publ.-Id: 28011 - Permalink


On the chemistry and mobility of hydrogen in the interstitial space of layered crystals h-BN, MoS2, and graphite
An, Y.; Kuc, A.; Petkov, P.; Lozada-Hidalgo, M.; Heine, T.;
Recently, transport and separation of hydrogen isotopes in the layered materials hexagonal boron nitride and molybdenum disulphide have been reported.[1] Here, based on first-principles calculations combined with well-tempered metadynamics simulations, we report the chemical interactions and mobility of protons (H+) and protium (H) atoms in the interstitial space of these layered materials. We show that both H as well as H+ can be transported between the layers of h-BN and MoS2 with low free energy barriers, while they are immobilized in graphite, in a good agreement with experiments. In h-BN and MoS2 the transport mechanism involves a hopping process between the nearby layers, which is assisted by the low-energy phonon shear modes of layers.
  • Poster
    Flatlands Beyond Graphene 2018, 03.-07.09.2018, Universität Leipzig, Germany

Publ.-Id: 28010 - Permalink


Electronic Properties of 2D van der Waals TMDCs Heterostructures from First Principles Calculations
Ramzan, M. S.; Kuc., A.;
Two-dimensional (2D) transition metal dichalcogenides (TMDCs) MX2 (M = Mo, W; X = S, Se) have attracted considerable attention in electronics and optoelectronic due to their intrinsic band gap[1]. Moreover, weak van der Waals interaction between layers make it possible to stack different TMDCs layers to form heterostructures with new electronic properties. In this work we have studies effect of interfacing TMDCs with different chalcogen atoms and/or different transition atoms to study effect of interface and dielectric constant on electronics. We will show that by controlling ratio of layers and hero-interfaces, direct gap can be achieved in more than four layers which might be ideal for solar energy harvesting.
  • Poster
    Flatlands Beyond Graphene 2018, 03.-07.09.2018, Universität Leipzig, Germany

Publ.-Id: 28009 - Permalink


Conformational isomerism controls collective flexibility in metal-organic framework DUT-8(Ni)
Petkov, P. S.; Bon, V.; Hobday, C. L.; Kuc, A.; Melix, P.; Kaskel, S.; Düren, T.; Heine, T.;
Metal-organic frameworks (MOFs) are crystalline compounds, typically with large pores. Some MOFs show pronounced structural flexibility that may result in closing and re-opening these pores. Here we show that collective flexibility in a MOF – DUT-8(Ni) – is controlled by conformational isomerism. DUT-8(Ni), a pillared-layer MOF with Ni2 paddle-wheels, dabco pillars and naphthalene dicarboxylate (ndc) linkers, can crystallize in many conformational isomers that depend on the orientation of the non-linear ndc linkers with respect to each other. While the open form is compatible with several of these conformations, only one of them, with alternating linker orientations, is stable as closed form. We show, by means of first principles calculations, that in the stable closed form, the appreciable lattice strain is compensated by London-dispersion between the ndc linkers that arrange with maximum overlap in a stacking order similar to the stacking in graphite. We substantiate these results by well-tempered metadynamics calculations at the DFT-based Born-Oppenheimer potential energy surface, by refined X-ray diffraction data and by nitrogen adsorption data obtained by experiment and Grand-Canonical Monte-Carlo simulations based on the DFT-optimized and PXRD-derived geometries. While the reported origin of flexibility cannot be generalized to all flexible MOFs, it offers a rational design concept of folding mechanisms in switchable MOFs by exploitation of the stabilization effect of linker stacking in the closed form.

Publ.-Id: 28008 - Permalink


Non equilibrium anisotropic excitons in atomically thin ReS2
Urban, J. M.; Baranowski, M.; Kuc, A.; Klopotowski, L.; Surrente, A.; Ma, Y.; Wlodarczyk, D.; Suchocki, A.; Ovchinnikov, D.; Heine, T.; Maude, D. K.; Kis, A.; Plochocka, P.;
We present a systematic investigation of the electronic properties of bulk and few layer ReS2 van der Waals crystals using low temperature optical spectroscopy. Weak photoluminescence emission is observed from two non-degenerate band edge excitonic transitions separated by ∼ 20 meV. The comparable emission intensity of both excitonic transitions is incompatible with a fully thermalized (Boltzmann) distribution of excitons, indicating the hot nature of the emission. While DFT calcu- lations predict bilayer ReS2 to have a direct fundamental band gap, our optical data suggests that the fundamental gap is indirect in all cases.

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  • Secondary publication expected from 02.11.2019

Publ.-Id: 28007 - Permalink


2D Crystals in Three Dimensions: Electronic Decoupling of Single-Layered Platelets in Colloidal Nanoparticles
Kempt, R.; Kuc, A.; Han, J. H.; Cheon, J.; Heine, T.;
Two-dimensional crystals, single sheets of layered materials, often show distinct properties desired for optoelectronic applications, such as larger and direct band gaps, valley- and spin-orbit effects. Being atomically thin, the low amount of material is a bottleneck in photophysical and photochemical applications. Here, we propose the formation of stacks of two-dimensional crystals intercalated with small surfactant molecules. We show, using first principles calculations, that already very short surfactant methyl amine electronically decouples the layers. We demonstrate the indirect-direct band gap transition characteristic for Group 6 transition metal dichalcogenides experimentally by observing the emergence of a strong photoluminescence signal for ethoxide-intercalated WSe2 and MoSe2 multilayered nanoparticles with lateral size of about 10 nm and beyond. The proposed hybrid materials offer the highest possible density of the two-dimensional crystals with electronic properties typical for monolayers. Variation of the surfactant’s chemical potential allows fine-tuning of electronic properties and potentially elimination of trap states caused by defects.

Publ.-Id: 28006 - Permalink


Electronic properties of 2D and 1D inorganic materials for applications in nano(opto)electronics
Kuc, A.;
The nanoelectronic industry is rapidly approaching limits of the silicon-technology, what leads to a necessity of developing new technologies, which would replace silicon in the future. Therefore, searching for materials that perform better than silicon at the atomic scale became a very important topic in the electronic and materials sciences in the past decades. Recently, two-dimensional (2D) layered materials, such as graphene, black phosphorous, silicene, or transition-metal dichalcogenides (TMCs), have attracted great attention, because of their extraordinary electronic properties and, at the same time, very good mechanical stability, which are desired features for nanoelectornic applications. The progress in the production of such 2D crystals grows rapidly every year, therefore, it is very important to estimate, understand, and explore the fundamental physics of these materials, in order to boost breakthrough technologies.
Layered transition-metal dichalcogenides have gained increasing attention ever since the seminal works published in 2010 and 2011, showing phenomenal electronic properties of monolayered systems, their easy exfoliation from bulk materials, due to the weak interlayer interactions, as well as, their applications as building blocks in the nanoelectronic logical devices. In this thesis, we present selected research based of density-functional theory, which has been carried out on the subject of electronic structure of TMC and other 2D crystals. These materials exhibit electronic properties, which are easily tuned by external modulators, such as tensile strain, doping, electric or magnetic fields, formation of different polytypes. The change in the electronic properties of semiconducting TMCs due to these external modulators vary in a wide range, e.g., semiconductor-metal transition, Rashba, Zeeman and Stark effects, induced spin-orbit coupling in centrosymmetric bilayered forms by breaking of inversion symmetry, topologically protected states in topological insulators. We also present the coherent transport properties of these 2D materials using calculations based on the density functional based tight-binding method in combination with the non-equilibrium Green’s function technique and the Landauer-Büttiker formula.
We show that the intrinsic electronic structure of MoS2 and other semiconducting TMCs change with the number of layers in the film. The indirect-band gap in the bulks changes to a direct-band gap in the monolayers and the size of the band gap is nearly 1 eV larger for the latter forms. On top of the electronic band gaps, which are mainly discussed in this thesis, TMC exhibit also very large exciton binding energies, which need to be taken into account, when discussing overall electronic properties. TMC monolayers exhibit very large spin-orbit splitting in the valence bands, which varies between 150 and almost 500 meV, depending on the stoichiometry. Stacking different monolayers of TMC materials results in reduced direct-band gaps with much smaller values than the respective pure materials, which comes from the formation of the type II heterostructures. In such heterostructures, the valence band maximum is formed from the states of different layers. This results in materials with excitons localized in such a way that the electron is located in one layer and the hole in the other.
We believe that the knowledge gained from the research presented in this thesis can provide new perspectives for the applications of TMC materials in the next generation of nano(opto)electronic devices.
  • Other
    Jacobs University Bremen, 2018
    Mentor: Prof. Thomas Heine

Publ.-Id: 28005 - Permalink


Photochemical creation of covalent organic 2D monolayer objects in defined shapes via a lithographic 2D-polymerization
Servalli, M.; Celebi, K.; Payamyar, P.; Zheng, L.; Polozij, M.; Lowe∥, B.; Kuc, A.; Schwarz, T.; Thorwarth, K.; Borgschulte○, A.; Heine, T.; Zenobi, R.; Schlüter, A. D.;
In this work, we prepare Langmuir-Blodgett monolayers with a trifunctional amphiphilic anthraphane monomer. Upon spreading at the air/water interface, the monomers self-assemble into 1 nm-thin monolayer islands, which are highly fluorescent and can be visualized by naked eye upon excitation. In-situ fluorescence spectroscopy indicates that in the monolayers, all the anthracene units of the monomers are stacked face-to-face forming excimer pairs, whereas at the edges of the monolayers free anthracenes are present acting as edge groups. Irradiation of the monolayer triggers [4+4]-cycloadditions among the excimer pairs, effectively resulting in a two-dimensional polymerization. The polymerization reaction also completely quenches the fluorescence, allowing to draw patterns on the monomer monolayers. More interestingly, after transferring the monomer monolayer on a solid substrate, by employing masks or the laser of a confo-cal scanning microscope, it is possible to arbitrarily select the parts of the monolayer that one wants to polymerize. The unpolymerized regions can then be washed away from the substrate, leaving two-dimensional macromolecular monolayer objects of the desired shape. This is the first photolithographic process that employs 2D-polymerizations and affords 1 nm-thin coatings.

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  • Secondary publication expected from 16.10.2019

Publ.-Id: 28004 - Permalink


Probing charge transfer characteristics in a donor–acceptor metal–organic framework by Raman spectroelectrochemistry and pressure-dependence studies
Usov, P. M.; Leong, C. F.; Chan, B.; Hayashi, M.; Kitagawa, H.; Sutton, J. J.; Gordon, K. C.; Hod, I.; Farha, O. K.; Hupp, J. T.; Addicoat, M.; Kuc, A. B.; Heine, T.; D’Alessandro, D. M.;
The stimuli responsive behaviour of charge transfer donor–acceptor metal–organic frameworks (MOFs) remains an understudied phenomenon which may have applications in tuneable electronic materials. We now report the modification of donor–acceptor charge transfer characteristics in a semiconducting tet- rathiafulvalene–naphthalene diimide-based MOF under applied electrochemical bias and pressure. We employ a facile solid state in situ Raman spectroelectrochemical technique, applied for the first time in the characterisation of electroactive MOFs, to monitor the formation of a new complex TTFTC􏰀+–DPNI from a largely neutral system, upon electrochemical oxidation of the framework. In situ pressure- dependent Raman spectroscopy and powder X-ray diffraction experiments performed in a diamond anvil cell revealed blue shifts in the donor and acceptor vibrational modes in addition to contractions in the unit cell which are indicative of bond shortening. This study demonstrates the utility of in situ Raman spectroscopic techniques in the characterisation of redox-active MOFs and the elucidation of their electronic behaviours.

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  • Secondary publication expected

Publ.-Id: 28003 - Permalink


Electronic structure of defective transition-metal dichalcogenides: theoretical investigations
Kuc, A.;
We have investigated the electronic structure changes of transition-metal dichalcogenides (TMCs), when various structural defects are present [1]. Healing of the defects by formation of sandwich materials will be also discussed [2]. Moreover, adsorption of small molecules on the defect sites were investigeted and the resulting the band structures will be presented [3].
Defects have very strong influence on the electronic properties of TMC materials, especially on their electronic transport, which could be strongly suppressed in the presence of large defect concentration. Defects can be healed by donation of, e.g. chalcogen atoms, from other TMC layers in a sandwich materials. Moreover, in experiments, the defect sites are not free and different molecules could be adsorbed, depending on the conditions in which the defects are formed.
Keywords: Electronic properties of TMDCs
  • Lecture (Conference)
    Hengstberger Symposium, 22.-24.10.2018, Heidelberg, Germany

Publ.-Id: 28002 - Permalink


Effiziente Merkmalsextraktion für eine Echtzeit- Bilddatenauswertung der ultraschnellen Röntgentomographie
Boesler, M.;
In dieser Arbeit wurde eine Bildverarbeitungsstrategie entwickelt, die eine automatische Erkennung von Objekten in Bildern der ultraschnellen Elektronenstrahl Röntgentomographie ermöglicht. Diese basiert auf einer pixelorientierten Segmentierung des geglätteten dynamischen Bildanteils.
Dabei wurden in der Auswahl der Algorithmen die problemspezifischen Voraussetzungen und Anforderungen, insbesondere an den Rechenaufwand und die Parallelisierbarkeit, berücksichtigt. Die entwickelte Bildverarbeitungsstrategie wurde an simulierten Bildern validiert. Dabei wurde zuerst eine für den betrachteten Parameterbereich optimale Filtergröße von 2 in z-Richtung bestimmt, sodass Objekte im Rahmen des gewählten Parameterbereiches sicher detektiert werden. Schließlich wurde der Einfluss unterschiedlicher Signal-Rausch-Verhältnisse, realisiert durch verschiedene Rauschamplituden, untersucht. Dabei hat sich gezeigt, dass die automatische Auswahl des Algorithmus zur Schwellwertbestimmung und eine damit zusammenhängende Fehleinschätzung der Pixelzahlen erheblich vom Signal-Rausch-Verhältnis abhängt. Abschließend wurde der Einfluss der Bildqualität, hervorgerufen durch eine Anpassung der Rekonstruktionsparameter, auf die Funktionsfähigkeit der Bildverarbeitungsstrategie studiert. Hierbei wurde festgestellt, dass eine Änderung der Zahl virtueller Parallelprojektionen qualitativ mit der Variation der Rauschamplitude übereinstimmt. Des Weiteren konnte beobachtet werden, dass sich eine geringere Bildauflösung auswirkt, als würde man kleinere Objekte betrachten.
Keywords: ultrafast X-ray, computed tomography, image processing, segmentation
  • Bachelor thesis
    TU Chemnitz, 2018
    Mentor: Dominic Windisch, Martina Bieberle, Guido Juckeland, Sibylle Gemming
    35 Seiten

Publ.-Id: 28001 - Permalink


Targeting cyclic nucleotide phosphodiesterase 5 (PDE5) in brain: Toward the development of a PET radioligand labeled with fluorine-18
Wenzel, B.; Liu, J.; Dukic-Stefanovic, S.; Deuther-Conrad, W.; Teodoro, R.; Ludwig, F.-A.; Chezal, J.-M.; Moreau, E.; Brust, P.; Maisonial-Besset, A.;
With the aim to develop a specific radioligand for imaging the cyclic nucleotide phosphodiesterase PDE5 in brain by positron emission tomography (PET), seven new fluorinated inhibitors (3 – 9) were synthesized on the basis of a quinoline core. The inhibitory activity for PDE5 together with a panel of other PDEs was determined in vitro and two derivatives were selected for IC50 value determination. The most promising compound 7 (IC50 = 5.92 nM), containing a 3-fluoroazetidine moiety, was further radiolabeled by nucleophilic aliphatic substitution of two different leaving groups (nosylate and tosylate) using [18F]fluoride. The use of the nosylate precursor and tetra-n-butyl ammonium [18F]fluoride ([18F]TBAF) in 3-methyl-3-pentanol combined with the addition of a small amount of water proved to be best labeling conditions achieving a RCY of 4.9 ± 1.5% in an automated procedure. Preliminary biological investigations in vitro and in vivo were performed to characterize the new PDE5 radioligand. Metabolism studies of [18F]7 in mice revealed a fast metabolic degradation with the formation of radiometabolites which have been detected in the brain.
Keywords: PDE5, 18F-radiolabeling, nosylate, tosylate, 18F-fluoroazetidine

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  • Secondary publication expected from 28.01.2020

Publ.-Id: 28000 - Permalink


High-Level Programming Approaches For Accelerators
Chandrasekaran, S.ORC; Juckeland, G.ORC
The Third Workshop on Accelerator Programming using Directives (WACCPD) was co-located with SC 2016 held on November 14, 2016, at Salt Lake City, Utah, USA. The workshop solicited papers on topics including hybrid heterogeneous or many-core programming with accelerator directives with other models (i.e., OpenMP, MPI, OpenSHMEM), scientific libraries interoperability with accelerator directives, programming experience porting applications in any domain, language-based extensions, and modelling and performance analysis tools.
Among the 20 submissions to the WACCPD workshop, we invited authors of seven papers to submit their extended manuscripts to a special issue with IJHPCN. The authors were asked to extend their paper by at the least 30% for the special issue by adding newer contents.
These seven manuscripts were peer-reviewed and the review process for the special issue was not double blind, i.e., authors were known to reviewers. Submissions were judged on correctness, originality, technical strength, and significance, quality of presentation, and interest and relevance to the conference scope. All the sevenmanuscripts were accepted to the special issue after two rounds of review.
  • Book (Editorship)
    Olney: Inderscience Enterprises Ltd., 2019
    128 Seiten
    ISBN: 1740-0570

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Publ.-Id: 27999 - Permalink


Strong Uranium(VI) Binding onto Bovine Milk Proteins, Selected Protein Sequences and Model Peptides
Zänker, H.; Heine, K.; Weiss, S.; Brendler, V.; Husar, R.; Bernhard, G.; Gloe, K.; Henle, T.; Barkleit, A.ORC
Hexavalent uranium is ubiquitous in the environment. In view of the chemical and radiochemical toxicity of uranium(VI) a good knowledge of its possible interactions in the environment is crucial. The aim of this work was to identify typical binding and sorption characteristics of uranium(VI) with both the pure bovine milk protein β-casein and diverse related protein mixtures (caseins, whey proteins). For comparison selected model peptides representing the amino acid sequence 13-16 of β-casein and dephosphorylated β-casein were also studied. Complexation studies using potentiometric titration and time-resolved laser-induced fluorescence spectroscopy revealed that the phosphoryl-containing proteins form uranium(VI) complexes of higher stability than the structure-analog phosphoryl-free proteins. That is in agreement with the sorption experiments showing a significantly higher affinity of caseins towards uranium(VI) in comparison to whey proteins. On the other hand, the total sorption capacity of caseins is lower than that of whey proteins. The discussed binding behavior of milk proteins to uranium(VI) might open up interesting perspectives for sustainable techniques of uranium(VI) removal from aqueous solutions. That was further demonstrated by batch experiments on the removal of uranium(VI) from mineral water samples.

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  • Secondary publication expected from 12.03.2020

Publ.-Id: 27998 - Permalink


Bioflotation: Verwendung der amphiphilen Siderophore Marinobactin im Prozess der Schaumflotation
Schrader, S.; Kutschke, S.; Pollmann, K.; Rudolph, M.;
Der Bedarf metallischer Rohstoffe ist in den vergangenen Jahren stetig gestiegen. Dieser Nachfrage allerdings gerecht zu werden, gestaltet sich zunehmen schwieriger, da sowohl primäre als auch sekundäre Rohstoffquellen immer komplexer werden. Um dieser Herausforderung gegenüber zu treten, müssen neue Wege beschritten werden. Eine Möglichkeit stellt dabei die Kombination der Biotechnologie mit klassischen Methoden der Aufbereitung dar. So soll in dieser Arbeit die biotechnologische Produktion von Siderophoren und deren Anwendung im Prozess der Schaumflotation vorgestellt werden. Siderophoren sind kleine organische Moleküle, welche eine hohe Affinität besitzen Eisen zu binden, aber auch starke Komplexe mit anderen Metallen formen können. Ihre Bildung erfolgt durch Mikroorganismen (aerobe Bakterien und Pilze) sowie Pflanzen bei einer geringen Bioverfügbarkeit von Eisen in deren Umgebung. Speziell die Gruppe der amphiphilen Siderophoren ist für die vorgesehene Anwendung von besonderem Interesse. Der hydrophile Bereich, welcher die funktionellen Hydroxamaten-Gruppen beinhalte, ist für die Bindung des Metalls zuständig, wohingegen der hydrophobe Teil, dargestellt durch unterschiedlich lange Fettsäureschwänze, in Interaktion mit der Blase treten soll. Beide Struktureinheiten finden bereits unabhängig erfolgreich Anwendung im Prozess der Flotation, werden allerdings bisher vorwiegend durch die chemische Industrie zur Verfügung gestellt.
Diese Arbeit stellt zum einen eine verbesserte Produktion der amphiphilen Siderophore Marinobactin unter der erstmaligen Verwendung eines Bioreaktors dar.
Weiterhin werden erste Experimente unterschiedlichster Maßstäbe zur Untersuchung von Interaktions- und Flotationsvorgängen vorgestellt. Dies erfolgt mit Hilfe des „Bubble-pick-up-Tests“, der Mikroflotation in der Halimond Röhre sowie Flotationsversuchen im ein Liter Labormaßstab. Dabei wurden eisen- und kupferhaltige Minerale getestet.
Die Verwendung amphiphiler Siderophoren als Biochemikalie in der Schaumflotation birgt das Potenzial diesen klassischen Prozess der Aufbereitung nachhaltiger zu gestalten und als Bioflotation zu definieren. Dies soll zum einen mit der Reduktion der bisher verwendeten Chemikalien erfolgen. Zum anderen sollen spezifische Metallbindungen mit Hilfe der Siderophoren einen gezielteren und effizienteren Prozess formen. Die erfolgreiche Etablierung eines Bioflotation Prozesses würde dann auch eine wichtige Ergänzung für den Bereich der Biohydrometallurgie darstellen.
Keywords: Marinobactin, Marinobacter, Flotation, Bioflotation, Siderophore
  • Poster
    Tagung Aufbereitung und Recycling, 14.-15.11.2018, Freiberg, Deutschland

Publ.-Id: 27997 - Permalink


Application of amphiphilic siderophores in froth flotation process
Schrader, S.; Kutschke, S.; Rudolph, M.; Pollmann, K.;
Siderophores are biomolecules, which can form strong complexes with different metals. They are produced by microorganisms and a biotechnological production of these chelators offers an application in different processing methods. Particularly amphiphilic siderophores are very interesting for the froth flotation process. The hydrophilic part, carrying hydroxamate groups is responsible for the binding of the metals. Flotation agents produced by the chemical industry with the same functional groups have already been applied successfully in this processing method. It can be suggested, that siderophores carrying the same functional groups, also work well as collectors. The fatty acid tail, that is representing the hydrophobic part, gets in contact with the bubbles and avoid additional chemicals and further working steps for making the target mineral particles hydrophobic. The aim of this study is to show the usage of amphiphilic siderophores in froth flotation process in different scales and with different minerals.
Keywords: Siderophore, Marinobactin, Marinobacter, Flotation, Bioflotation
  • Lecture (Conference)
    Sustainable Minerals 2018, 14.-15.06.2018, Windhoek, Namibia

Publ.-Id: 27996 - Permalink


Production of amphiphilic siderophores for bioflotation process
Schrader, S.; Kutschke, S.; Rudolph, M.; Pollmann, K.;
Siderophores are small organic molecules with a high affinity for binding Fe(III) and to form strong complexes also with other metals. They are produced by microorganisms (aerobic bacteria and fungi) and some plants to equalize the low bioavailability of iron in their environment.
A lot of microorganisms and their produced siderophores have already been identified and analyzed in detail. Until now, siderophores are only used as medicine against iron or heavy metal poisoning. The biotechnological production offers the application in very different fields, like extraction, recovery and treating of different metals. Especially the group of amphiphilic siderophores are very interesting for the classical froth flotation process. The aim of this study is the optimized and efficient biotechnological production of the amphiphilic siderophore Marinobactin by the marine bacterium Marinobacter sp. DS40M6 and to show for the first time that it is possible to use these biomolecules in froth flotation process.
Keywords: Siderophore, Marinobactin, Marinobacter, Flotation, Bioflotation
  • Poster
    Biohydrometallurgy 2018, 11.-13.06.2018, Windhoek, Namibia

Publ.-Id: 27995 - Permalink


Voltage-controlled ON-OFF ferromagnetism at room temperature in a single metal oxide film
Quintana, A.; Menéndez, E.; Liedke, M. O.; Butterling, M.; Wagner, A.; Sireus, V.; Torruella, P.; Estradé, S.; Peiró, F.; Dendooven, J.; Detavernier, C.; Murray, P.; Gilbert, D. A.; Liu, K.; Pellicer, E.; Nogués, J.; Sort, J.;
Electric-field controlled magnetism can boost energy-efficiency in widespread applications. However, technologically, this effect is facing important challenges: mechanical failure in strain-mediated piezoelectric/magnetostrictive devices, dearth of room-temperature multiferroics or stringent thickness limitations in electrically-charged metallic films. Voltage driven ion motion (magneto-ionics) circumvents most of these drawbacks while offering unprecedented magnetoelectric phenomena. Nevertheless, magneto-ionics typically requires heat-treatments and multi-component heterostructures. Here we report on the electrolytegated and defect-mediated O and Co transport in a Co3O4 single layer which allows for roomtemperature voltage-controlled ON-OFF ferromagnetism (magnetic switch) via internal reduction/oxidation processes. Negative voltages partially reduce Co3O4 to Co (ferromagnetism: ON), resulting in graded films including Co- and O-rich areas. Positive bias oxidizes Co back to Co3O4 (paramagnetism: OFF). This electric-field-induced atomic-scale reconfiguration process is compositionally, structurally and magnetically reversible and self sustained since no oxygen source other than the Co3O4 itself is required. This novel process could lead to new electric-field-controlled device concepts for spintronics
Keywords: electric field, ionic transport, magnetic phase transition, Co3O4, positron annihilation, spintronic

Publ.-Id: 27994 - Permalink


Fourier Analysis of Cerebral Metabolism of Glucose: Gender Differences in Mechanisms of Color Processing in the Ventral and Dorsal Streams in Mice
Njemanze, P. C.; Kranz, M.; Brust, P.;
Conventional imaging methods could not distinguish processes within the ventral and dorsal streams. The application of Fourier time series analysis was helpful to segregate changes in the ventral and dorsal streams of the visual system in male and female mice. The present study measured the accumulation of [18F]fluorodeoxyglucose ([18F]FDG) in the mouse brain using small animal positron emission tomography and magnetic resonance imaging (PET/MRI) during light stimulation with blue and yellow filters compared to darkness condition. Fourier analysis was performed using mean standardized uptake values (SUV) of [18F]FDG for each stimulus condition to derive spectral density estimates for each condition. In male mice, luminance opponency occurred by S-peak changes in the sub-cortical retino-geniculate pathways in the dorsal stream supplied by ganglionic arteries in the left visual cortex, while chromatic opponency involved C-peak changes in the cortico-subcortical pathways in the ventral stream perfused by cortical arteries in the left visual cortex. In female mice, there was resonance phenomenon at C-peak in the ventral stream perfused by the cortical arteries in the right visual cortex in female mice during luminance processing. Conversely, chromatic opponency occurred by S-peak changes in the subcortical retino-geniculate pathways in the dorsal stream supplied by the ganglionic arteries in the right visual cortex. In conclusion, Fourier time series analysis uncovered distinct mechanisms of color processing in the ventral stream in male, while in female mice color processing was in the dorsal stream. It demonstrated that computation of colour processing as a conscious experience could have a wide range of applications neuroscience, artificial intelligence and quantum mechanics.
Keywords: chromatic opponency, sex differences, light wave, light particle, blood flow, frequency, resonance

Publ.-Id: 27992 - Permalink


Highly Sensitive Electromechanical Piezoresistive Pressure Sensors Based on Large-Area Layered PtSe2 Films
Wagner, S.; Yim, C.; Mcevoy, N.; Kataria, S.; Yokaribas, V.; Kuc, A.; Pindl, S.; Fritzen, C.-P.; Heine, T.; Duesberg, G. S.; Lemme, M. C.;
Two-dimensional (2D) layered materials are ideal for micro- and nanoelectromechanical systems (MEMS/NEMS) due to their ultimate thinness. Platinum diselenide (PtSe2), an exciting and unexplored 2D transition metal dichalcogenide material, is particularly interesting because its low temperature growth process is scalable and compatible with silicon technology. Here, we report the potential of thin PtSe2 films as electromechanical piezoresistive sensors. All experiments have been conducted with semimetallic PtSe2 films grown by thermally assisted conversion of platinum at a complementary metal−oxide−semiconductor (CMOS)-compatible temperature of 400 °C. We report high negative gauge factors of up to −85 obtained experimentally from PtSe2 strain gauges in a bending cantilever beam setup. Integrated NEMS piezoresistive pressure sensors with freestanding PMMA/PtSe2 membranes confirm the negative gauge factor and exhibit very high sensitivity, outperforming previously reported values by orders of magnitude. We employ density functional theory calculations to understand the origin of the measured negative gauge factor. Our results suggest PtSe2 as a very promising candidate for future NEMS applications, including integration into CMOS production lines.
Keywords: Pressure sensors, platinum diselenide, two-dimensional, gauge factors, strain sensors

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Publ.-Id: 27990 - Permalink


Ionenstrahlanalytik im Helium-Ionen-Mikroskop
Klingner, N.ORC
Die vorliegende Arbeit beschreibt die Implementierung ionenstrahlanalytischer Methoden zur Charakterisierung der Probenzusammensetzung in einem Helium-Ionen-Mikroskop mit einem auf unter einen Nanometer fokussierten Ionenstrahl. Zur Bildgebung wird dieser im Mikroskop über Probenoberflächen gerastert und die lokale Ausbeute an Sekundärelektronen gemessen. Obwohl sich damit ein hoher topografischer Kontrast erzeugen lässt, lassen sich weder aus der Ausbeute noch aus der Energieverteilung der Sekundärelektronen verlässliche Aussagen zur chemischen Zusammensetzung der Probe treffen. Daher wurden in dieser Arbeit verschiedene ionenstrahlinduzierte Sekundärteilchen hinsichtlich ihrer Eignung für die Elementanalytik im Helium-Ionen-Mikroskop verglichen. Zur Evaluation standen der Informationsgehalt der Teilchen, deren Analysierbarkeit sowie deren verwertbare Ausbeute. Die Spektrometrie rückgestreuter Teilchen sowie die Sekundärionen-Massenspektrometrie wurden dabei als die geeignetsten Methoden identifiziert und im Detail untersucht. Gegenstand der Untersuchung waren physikalische Limitierungen und Nachweisgrenzen der Methoden sowie deren Eignung zum Einbau in ein Helium-Ionen-Mikroskop. Dazu wurden verschiedene Konzepte von Spektrometern evaluiert, erprobt und hinsichtlich ihrer Effizienz, Energieauflösung und Umsetzbarkeit im Mikroskop bewertet. Die Flugzeitspektrometrie durch Pulsen des primären Ionenstrahls konnte als die geeignetste Technik identifiziert werden und wurde erfolgreich in einem Helium-Ionen-Mikroskop implementiert. Der Messaufbau, die Signal- und Datenverarbeitung sowie vergleichende Simulationen werden detailliert beschrieben. Das Spektrometer wurde weiterhin ausführlich hinsichtlich Zeit-, Energie- und Massenauflösung charakterisiert. Es werden ortsaufgelöste Rückstreuspektren vorgestellt und damit erstmalig die Möglichkeit zur Ionenstrahlanalytik im Helium-Ionen-Mikroskop auf einer Größenskala von ≤ 60 nm aufgezeigt. Das Pulsen des primären Ionenstrahls erlaubt es zudem, die Technik der Sekundärionen-Massenspektrometrie anzuwenden. Diese Methode bietet Informationen zur molekularen Probenzusammensetzung und erreicht für einige Elemente niedrigere Nachweisgrenzen als die Rückstreuspektrometrie. Damit konnten erstmalig im Helium-Ionen-Mikroskop gemessene Sekundärionen-Massenspektren sowie die ortsaufgelöste Elementanalyse durch spektrometrierte Sekundärionen demonstriert werden. Die Ergebnisse dieser Arbeit sind in der Fachzeitschrift Ultramicroscopy Band 162 (2016) S. 91–97 veröffentlicht. Ab Oktober 2016 werden diese auch in Form eines Buchkapitels in dem Buch „Helium Ion Microscopy“, Springer Verlag Heidelberg zur Verfügung stehen.
Keywords: Helium-Ionen-Mikroskop, Ionenstrahlanalytik
  • Doctoral thesis
    TU Dresden, 2017
    Mentor: Jürgen Faßbender
    153 Seiten

Publ.-Id: 27989 - Permalink


NMR-based investigations of acyl-functionalized piperazines concerning their conformational behavior in solution
Steinberg, J.; Köckerling, M.; Wodtke, R.; Löser, R.; Mamat, C.ORC
Selected N-benzoylated piperazine derivatives were synthesized to study their conformational behavior using temperature-dependent 1H NMR spectroscopy. All investigated piperazine compounds occur as conformers at room temperature resulting from the reduced rotation of the partial amide double bond. Furthermore, a second conformational shape was observed for selected mono-N-benzoylated and unsymmetrically N,N’-substituted derivatives due to the limited change of the piperazine chair conformation. Therefore, two different coalescence points TC were determined and their resulting activation energy barriers ΔG# were calculated to be between 50 and 70 kJ/mol. In most of the cases, TC and ΔG# for the amide site appeared to be higher as for the amine site. Furthermore, benzoate moieties with electron withdrawing substituents like nitro show a higher rotational barrier compared to electron-releasing substitutents like methoxy. An additional aryl substituent connected at the amine site led to a reduced rotational barrier compared to the free secondary amine. To support and evidence the findings from the NMR analyses, single crystals of piperazines were obtained and XRD analyses were performed. To underline the results, two potential Tgase 2 inhibitors were investigated showing energy barriers with similar values.
Keywords: NMR, rotation barrier, piperazines, coalescence

Publ.-Id: 27988 - Permalink


Calix[4]crown-6 scaffold for the complexation of barium and radium
Bauer, D.; Reissig, F.; Steinberg, J.; Pietzsch, H.-J.; Steinbach, J.; Mamat, C.ORC
Radium is the heaviest known member of the alkaline earth metals and all 33 of its isotopes are radioactive. Two of these, radium-223 and radium-224, have suitable half-lives with 11.4 d and 3.6 d, respectively, and nuclear decay properties that make them useful tools for alpha particle therapy. Unfortunately, no suitable chelating agents are available for a stable complexation. Thus, radium-223 is only in use as radium chloride to treat bone metastases. For this purpose, a series of modified calix[4]crown-6 derivatives was synthesized to chelate heavy group 2 metal ions like barium, which serves as a non-radioactive surrogate for radium-223/-224.
The calix[4]arene framework can be seen as an ideal platform to build an optimized chelator. Two of the four hydroxy groups of the lower rim can be functionalized as deprotonizable groups to form a neutral complex with barium or radium; the remaining two are bridged by a crown ether moiety. With this concept, the advantages of the electrostatic, macrocyclic, and cryptate effect are combined. Another benefit of the calixcrowns is their easy access.
As a result, our calix[4]crowns were functionalized with either cyclic amide moieties or with deprotonizable groups like carboxylic acids or hydroxyl amines, and the corresponding barium complexes were synthesized.
To prove the ability of these chelators for a further usage in radiopharmacy, stability constants of the corresponding barium complexes were determined by using NMR and UV/Vis titration to determine logK values. Further extraction studies were performed to characterize the binding affinity of calixcrowns to barium-133 and radium-224.
Keywords: calixarene, alkaline earth metals, barium, radium
  • Poster
    The Third International Symposium on Technetium and other Radiometals in Chemistry and Medicine, 26.-29.09.2018, Bressanone, Italien

Publ.-Id: 27987 - Permalink


Chelatoren für die Komplexierung schwerer Erdalkalimetallionen
Reissig, F.; Bauer, D.; Pietzsch, H.-J.; Steinbach, J.; Mamat, C.;
Ziel:
Nach dem heutigen Stand sind keine geeigneten Chelatoren zur stabilen Komplexierung von schweren Erdalkalimetallen Barium und Radium bekannt. Da die Alphaemitter Radium-223 Radium-224 jedoch hohes therapeutisches Potential besitzen, ist die Entwicklung von multimodalen Liganden von großem Interesse. Ein solcher Ligand könnte eine Matched-Pair-Strategie eröffnen. Während Radium-223 und Radium-224 therapeutisch einsetzbar sind, besitzt Barium-131, welches analoge chemische Eigenschaften aufzeigt, gute diagnostische Eigenschaften. Bis jetzt ist die klinische Nutzung von Radium auf die Behandlung von Knochenmetastasen durch das calcimimetische Radiopharmakon [223Ra]RaCl2 (Xofigo®) beschränkt. Diese Anwendung gilt es zu erweitern.

Methodik:
Radium-224 wurde in Form seines Nitrats mittels Ionenaustauschchromatographie aus einem Thorium-228-Generator gewonnen. Als Bariumisotop für Extraktionsstudien wurde das langlebige und kommerziell erhältliche Radionuklid Barium-133 genutzt. Die Radiomarkierungen wurden mittels HPLC und Extraktionsstudien charakterisiert.
Stabilitätskonstanten wurden mit stabilem Barium mittels UV/Vis und Kalorimetrie berechnet. Mit den Radiometallen Barium-133 und Radium-224 konnten vergleichbare Konstanten mittels Zwei-Phasen-Extraktion (Wasser/Chloroform) bestimmt werden.
Als Liganden dienten unter anderem verschieden funktionalisierte, 18-Krone-6-überbrückte Calix[4]-arene.

Ergebnisse:
Es wurden vier Liganden auf Calix[4]-aren-Basis dargestellt und deren Interaktion mit Bariumionen untersucht. Ein relativ hohe Stabilitätskonstante konnte vor allem für ein Sulfonamid-Derivat ermittelt werden. Angeschlossene Extraktionsstudien zeigten für diesen Liganden eine nahezu vollständige Extraktion von [133Ba]Ba2+ aus der wässrigen Phase unter physiologischen Bedingungen.
Analoge Versuche wurden mit [224Ra]Ra2+ durchgeführt. Der Komplex zeigte dabei eine ähnliche Stabilität.
Schlussfolgerungen:
Der Sulfonamid-Ligand wurde als potenter Chelator für Radium/Barium identifiziert. Weitere Modifikationen werden erfolgen, um die Stabilität weiter zu erhöhen und eine Biokompatibilität zu ermöglichen. In-vitro- und in-vivo-Studien müssen vorbereitet werden.
Keywords: Calixarene, Erdalkalimetalle, Komplexierung, Barium, Radium
  • Lecture (Conference)
    23. Jahrestagung der Arbeitsgemeinschaft Radiochemie & Radiopharmazie, 20.-22.09.2018, Aachen, Deutschland

Publ.-Id: 27986 - Permalink


An Introduction to the SPEC High Performance Group and their HPC Benchmark Suites
Juckeland, G.ORC
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 - Permalink


Is It Here/There Yet? - Real Life Experiences of Generating/Evaluating Extreme Data Sets Around the World
Juckeland, G.ORC; Huebl, A.ORC; Bussmann, M.ORC
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 LogoContribution 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

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Publ.-Id: 27984 - Permalink


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 - Permalink


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 - Permalink


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.
  • Lecture (Conference)
    GEOBONN, 03.09.2018, Bonn, Germany

Publ.-Id: 27981 - Permalink


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 - Permalink


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 LogoContribution to proceedings
    WGSG Dublin IV, 27.-29.06.2018, Dublin, Ireland
  • Poster
    WGSG Dublin IV, 27.-29.06.2018, Dublin, Ireland

Publ.-Id: 27979 - Permalink


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 - Permalink


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.
  • Poster
    European Geosciences Union General Assembly 2018, 10.04.2018, Vienna, Austria

Publ.-Id: 27977 - Permalink


Controlling shallow- and deep-level dopants in silicon nanowires via non-equilibrium processing
Berencén, Y.ORC; 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 - Permalink


Formation of n- and p-type regions in individual Si/SiO2 core/shell nanowires by ion beam doping
Berencén, Y.ORC; 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.ORC
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

Downloads:

  • Secondary publication expected from 25.09.2019

Publ.-Id: 27975 - Permalink


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.;
Ziel/Aim:
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.
Methodik/Methods:
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.
Ergebnisse/Results:
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).
Schlussfolgerungen/Conclusions:
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 - Permalink


Ion acceleration with on-shot monitored ultra-high contrast using the DRACO Petawatt laser facility
Ziegler, T.ORC; Bernert, C.; Bock, S.; Brack, F.-E.; Bussmann, M.ORC; Garten, M.ORC; Kraft, S.ORC; Kroll, F.ORC; Metzkes-Ng, J.ORC; Obst, L.ORC; Oksenhendler, T.; Rehwald, M.ORC; Schlenvoigt, H.-P.ORC; Schramm, U.ORC; 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 - Permalink


All-optical shaping of laser-driven proton beam profiles
Ziegler, T.ORC; Obst-Huebl, L.ORC; Brack, F.-E.; Branco, J.; Bussmann, M.ORC; Cowan, T. E.ORC; Curry, C. B.ORC; Fiuza, F.ORC; Garten, M.ORC; Gauthier, M.ORC; Göde, S.; Glenzer, S. H.; Huebl, A.ORC; Irman, A.; Kim, J. B.; Kluge, T.ORC; Kraft, S.ORC; Kroll, F.ORC; Metzkes-Ng, J.ORC; Pausch, R.ORC; Prencipe, I.; Rehwald, M.ORC; Rödel, C.; Schlenvoigt, H.-P.ORC; Schramm, U.ORC; 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 - Permalink


A fine future - Flotation in times of circular economy and energy transition
Rudolph, M.ORC
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 LogoAT Mineral Processing 59(2018), 56-64

Publ.-Id: 27971 - Permalink


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 - Permalink


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).
Results
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.
Conclusion
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.

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Publ.-Id: 27969 - Permalink


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.
Results
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).
Conclusion
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 - Permalink


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

Downloads:

  • Secondary publication expected from 19.10.2019

Publ.-Id: 27967 - Permalink


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

Downloads:

  • Secondary publication expected from 07.03.2020

Publ.-Id: 27966 - Permalink


Scalable Multi-Platform PIC Simulations as an Open Science Service
Huebl, A.ORC; 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 - Permalink


Data Analysis and Simulations in Exascale Computing: Quō vādis?
Huebl, A.ORC; 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 - Permalink


Open, Any-Platform, Leadership-Scale Particle-in-Cell Simulations for Everyone
Huebl, A.ORC; 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 - Permalink


openPMD - An Open Standard for Particle-Mesh Data Files
Huebl, A.ORC; Lehe, R.ORC; Vay, J.-L.ORC; Grote, D. P.; Sbalzarini, I. F.ORC; Kuschel, S.; Sagan, D.ORC; Pérez, F.; Koller, F.ORC; Bussmann, M.ORC
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 - Permalink


HPC as a Tool for Better Science
Huebl, A.ORC; Juckeland, G.ORC
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 - Permalink


Modeling Laser-Plasma Interaction with PIConGPU
Huebl, A.ORC; 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 - Permalink


PIConGPU: Applications in Laser Ion Acceleration and Non-LTE Ionization Modeling
Huebl, A.ORC; 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 - Permalink


Accelerating Accelerator Research for Radiation Therapy of Tumors with PIConGPU
Huebl, A.ORC; 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 - Permalink


Next-Generation Simulations for XFEL-Plasma Interactions with Solid Density Targets with PIConGPU - Solutions for Predictive 3D Modeling
Huebl, A.ORC; 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 - Permalink


Open the Exascale Tool Chest for Predictive Plasma Modelling with PIConGPU
Huebl, A.ORC; 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 - Permalink


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 - Permalink


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

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Publ.-Id: 27954 - Permalink


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 - Permalink


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

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  • Secondary publication expected from 09.01.2020

Publ.-Id: 27951 - Permalink


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 - Permalink


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

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Publ.-Id: 27949 - Permalink


openPMD Example Data Sets from PIConGPU 0.2.0
Huebl, A.ORC
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.57
    License: CC-BY-4.0

Downloads:

Publ.-Id: 27948 - Permalink


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 - Permalink


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.ORC; 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 - Permalink


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 - Permalink


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

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  • Secondary publication expected

Publ.-Id: 27943 - Permalink


A realistic approach for the assessment of the consequences of heterogeneous boron dilution events in pressurized water reactors
Kliem, S.ORC; Grahn, A.; Bilodid, Y.ORC; 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

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  • Secondary publication expected from 01.08.2020

Publ.-Id: 27942 - Permalink


Analysis of moulded wood tube structure using gamma-ray computed tomography
Bieberle, A.ORC; Engmann, C.; Hartig, J.; Haller, P.

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

Downloads:

Publ.-Id: 27941 - Permalink


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.

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Publ.-Id: 27939 - Permalink


Experimental study of the mold flow induced by a swirling flow nozzle and electromagnetic stirring for continuous casting of round blooms
Schurmann, D.ORC; Willers, B.ORC; Hackl, G.; Tang, Y.; Eckert, S.ORC
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)

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  • Secondary publication expected from 06.03.2020

Publ.-Id: 27938 - Permalink


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 - Permalink


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 - Permalink


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 - Permalink


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 - Permalink


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

Publ.-Id: 27933 - Permalink


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

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  • Secondary publication expected from 22.02.2020

Publ.-Id: 27932 - Permalink


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 - Permalink


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 - Permalink


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 - Permalink


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