Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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31742 Publications
Ionization and reflux dependence of magnetic instability generation and probing inside laser-irradiated solid thin foils
Huang, L. G.; Schlenvoigt, H.-P.; Takabe, H.; Cowan, T. E.;
When an intense laser accelerated electron beam, with large current density on the order of 10^12 A/cm^2, enters a solid density plasma, it is well-known to be subject to a number of different types of instabilities that cause it to filament. In this work, we investigate the transport instability of a fast electron beam that is imprinted on the self-generated magnetic filaments inside the solid density plasmas using particle-in-cell simulations. By varying collisional ionization models, our simulations show that the atomic ionization process is crucial to determine the structure of the magnetic filaments. We further attribute the generation of bulk magnetic filaments to Weibel-like instability mechanism caused by counter-propagating hot forward-bulk return current streams and counterpropagating hot forward-reflux current streams. It is found that the magnetic fields in the filament channels near the rear surface are around one order of magnitude higher than those near the front surface of the thin solid target. This asymmetry is likely induced by the very different properties of bulk electron stream and hot reflux electron stream in terms of density and velocity distribution. Finally, we propose to probe the magnetic fields inside the solid density plasmas by X-Ray polarimetry via Faraday rotation using X-Ray free electron lasers (XFELs). The synthetic simulations show that XFELs are capable to detect the magnetic fields from relativistic laser-solid interactions.
Keywords: Laser plasma interactions, Weibel instability,XFEL,Faraday rotation

Publ.-Id: 26120 - Permalink


Reactive transport modelling based on actual parameters obtained from GeoPET analysis of column experiments
Karimzadeh, L.; Schymura, S.; Kulenkampff, J.; Franke, K.; Eichelbaum, S.; Lippmann-Pipke, J.; Fischer, C.;
Abstract

GeoPET is the application of positron emission tomography (PET) for direct, non-destructive, quantitative spatiotemporal measurement and visualization of fluid transport in natural geological media on drill-core scale [1-5]. Here, we present new results that focus on reactive transport simulations on a drill core sample in 4D (3D+t) by using velocity fields (vx, vy, vz) obtained from GeoPET measurements of a fractured rock sample.
A mechanically induced fracture was obtained during a geomechanical shear test in a calciferous sandstone drill core sampled from the Permian Kupferschiefer ore formation (Rudna mine, Poland). Column leaching experiments using the core sample (D = 6 cm, L = 10 cm) were carried out in a plexiglas reaction cell in the laboratory at atmospheric pressure. The leaching solutions were injected with constant flow rate of 1 mL/h in three stages: First, a moderately hard synthetic fresh water (pH = 8.5) was used as inflow solution for 22 days in order to remove the salts minerals. Second, an acidic solution with pH of 1.5 (H2SO4) was injected to reduce the carbonat content within another 23 days. In stage three, 0.17 mol/L concentrated ferric iron was added to the acidic inflow solution (pH 1.5, H2SO4) for 20 days in order to dissolve mainly the Cu-sulfid minerals and increase the copper recovery from sample. The tracer transport in the sample was monitored by PET technique and the velocity fields derived by using an image analysing algorithm. The velocity fields then imported in the COMSOL Multyphisics to simulate and calibrate the fluidflow. Three dimensional modeling by means of iCP 1.3[6] (an interface coupling of the finite element based code COMSOL Multiphysics® with the geochemical code PhreeqC[7]) was performed to predict the leaching process and solute transport through the core sample by using kinetic mineral dissolution and precipitation data (BRGM database). The reactive transport model results are compared and refined by using the laboratory column leaching experiments.
Keywords: Reactive transport modeling, GeoPET, Column leaching experiment
  • Poster
    Reactive Transport in the Earth and Environmental Sciences in the 21st Century, 02.-06.10.2017, Amboise, France

Publ.-Id: 26119 - Permalink


Scaling EUV and X-ray Thomson sources to optical free-electron laser operation with Traveling-Wave Thomson-Scattering
Steiniger, K.; Albach, D.; Debus, A.; Loeser, M.; Pausch, R.; Roeser, F.; Schramm, U.; Siebold, M.; Bussmann, M.;
Traveling-Wave Thomson-Scattering (TWTS) allows for the realization of ultra-compact, inherently synchronized and highly brilliant light sources by providing optical undulators with hundreds to thousands of undulator periods from high-power, pulse-front tilted lasers pulses.

With TWTS the realization of optical free-electron lasers (OFELs) as well as incoherent radiation sources with orders of magnitude higher photon yields than classic head-on Thomson sources becomes possible with state-of-the-art technology in electron accelerators and laser systems.

The talk will show how pulse-front tilted, petawatt class laser pulses and relativistic electrons work together in a side-scattering geometry, where laser end electron propagation direction of motion enclose an angle, to realize long but compact optical undulators with centimeter to meter-scale interaction distances at sub-millimeter undulator periods. Example setups of TWTS OFELs emitting ultraviolet radiation are presented which are realizable today with existing technology for electron accelerators and laser systems. Especially the ultra-low emittance of laser wakefield accelerated electron bunches can be exploited to compensate for their one percent level energy spreads. Further an experimental setup is presented to generate the tilted TWTS laser pulses. This setup strategy provides dispersion compensation, required due to angular dispersion of the laser pulse, and is especially relevant when building compact, high-yield hard X-ray TWTS sources in large interaction angle setups.
Keywords: Optical free-electron laser, traveling wave, thomson scattering, vuv, euv, x-ray, laser dispersion control
  • Lecture (Conference)
    SPIE Optics + Optoelectronics, 24.-27.04.2017, Prague, Czech Republic

Publ.-Id: 26118 - Permalink


Design of optical setups for high-yield optical undulators in the Traveling-Wave Thomson-Scattering geometry
Steiniger, K.; Debus, A.; Albach, D.; Loeser, M.; Pausch, R.; Roeser, F.; Schramm, U.; Siebold, M.; Bussmann, M.;
Traveling-Wave Thomson-Scattering (TWTS) can realize ultra-compact, inherently synchronized and highly brilliant light sources from the ultraviolet to the hard X-ray range. In TWTS ultrashort laser pulses and relativistic electron bunches are utilized in a side-scattering geometry where laser pulse and electron bunch direction of motion enclose an interaction angle. Thereby the laser electric field provides the undulator field in which electrons oscillate and emit radiation during interaction. By employing tilted laser pulses TWTS ensures continuous overlap of laser and electrons while these traverse the laser cross-sectional area. Tilting the laser pulse-front compensates the spatial separation of electrons and laser at begin and end of the interaction originating from their different propagation directions. Combining laser pulse-front tilt and side-scattering in TWTS enables interaction over hundreds to thousands of optical undulator periods, enough to allow for optical free-electron laser (OFEL) operation since microbunching of the electron bunch and thus coherent radiation amplification can be achieved.
After shortly introducing the TWTS scattering geometry, the design of optical setups to generate the tilted TWTS laser pulses is presented in the talk. This setup strategy provides dispersion compensation, required due to angular dispersion of the laser pulse, and is especially relevant when building compact, high-yield hard X-ray TWTS sources in large interaction angle setups. Determining parameters of the setup is illustrated in an example of an ultraviolet TWTS OFEL and an outlook is given on the design of hard X-ray TWTS sources.
Keywords: Traveling wave, thomson scattering, laser dispersion control, x-ray source
  • Lecture (Conference)
    DPG Frühjahrstagung Dresden, 19.-24.03.2017, Dresden, Deutschland

Publ.-Id: 26116 - Permalink


IAEA CRP benchmark of ROCOM PTS test case for the use of CFD in reactor design using ANSYS CFX
Höhne, T.;
Over the last 15 years, considerable effort has been expended in assembling the available information on the use of CFD in the nuclear reactor safety field. Typical application areas here are heterogeneous mixing and heat transfer in complex geometries, buoyancy-induced natural and mixed convection, etc., with specific reference to NRS accident scenarios such as Pressurized Thermal Shock (PTS), boron dilution, hydrogen build-up in containments, thermal fatigue and thermal striping issues, etc. The development, verification and validation of CFD codes in respect to NPP design necessitates further work on the complex physical modelling processes involved, and on the development of efficient numerical schemes needed to solve the basic equations. Therefore, a set of ROCOM CFD-grade test data were made available to set up an IAEA benchmark, relating to Pressurized Thermal Shock (PTS) scenarios. The benchmark deals with the injection of the relatively cold Emergency Core Cooling (ECC) water which can induce buoyancy-driven stratification. Data obtained from the PTS experiment were compared with predictions obtained from the CFD software ANSYS CFX.

The results of the experiment and of the numerical calculations show that mixing is dominated by buoyancy effects: at higher mass flow rates (close to nominal conditions) the injected slug propagates in the circumferential direction around the core barrel. Buoyancy effects reduce this propagation. The ECC water falls in an almost vertical path and reaches the lower down-comer sen¬sor directly below the inlet nozzle. Therefore, density effects play an important role during natural convection with ECC injection in PWRs. CFD was able to predict well the observed flow patterns and mixing phenomena.
Keywords: ROCOM, CFD, PTS, RPV, CFX, ECC, PWR
  • Lecture (Conference)
    Fourth Research Coordination Meeting on the Application of Computational Fluid Dynamics Codes for Nuclear Power Plant Design, 08.11.2017, Wien, Österreich

Publ.-Id: 26114 - Permalink


Ex-situ doping and Ohmic contact formation with low contact resistance on MBE grown GeSn on Si
Prucnal, S.; Augel, L.; Schulze, J.; Fischer, I. A.; Berencén, Y.; Hübner, R.; Böttger, R.; Rebohle, L.; Skorupa, W.; Wang, M.; Voelskow, M.; Helm, M.; Zhou, S.;
GeSn with quasi-direct band gap is one of the most promising semiconductor materials for light emitters integrated with CMOS technology. The equilibrium solid solubility limit (SSL) of Sn in Ge is in the range of 0.5 % and the predicted theoretical Sn concentration needed for the direct band gap formation is above 5 %. This means that GeSn with direct band gap is metastable and any related material process cannot be thermal equilibrium. Here we propose to utilize strongly non-equilibrium processing i.e. ion implantation followed by millisecond range flash lamp annealing (FLA), for doping and the formation of Ohmic contacts with low contact resistance on Ge0.95Sn0.05. The effective carrier concentration in P+ implanted Ge0.95Sn0.05 layer followed by FLA for 3 ms is above 5×10^19cm-3 with a specific contact resistance rc=4×10^-6Ωcm2. NiGe for Ohmic contact is made by Ni diffusion into GeSn during a single 3 ms long flash pulse. TEM images reveal that NiGe is polycrystalline but with an atomically sharp interface between the metal contact and GeSn. The influence of non-equilibrium processing (ion implantation and FLA) on the optical, electrical and microstructural properties of the GeSn layer grown by MBE on Si will be discussed in details.
Keywords: GeSn, MBE, doping, flash lamp annealing
  • Poster
    EMRS Fall Meeting 2017, 18.-21.09.2017, Warsaw, Poland

Publ.-Id: 26113 - Permalink


Strategies for high doping of Ge
Prucnal, S.;
One of the main obstacles towards wide application of Ge in nanoelectronics is the lack of an efficient doping method for the fabrication of heavily doped Ge layers with well controlled junction depth. In fact, n-type doping of Ge is a key bottleneck in the realization of advanced negative-channel metal-oxide-semiconductor (NMOS) devices. Here an overview of different doping techniques will be presented. Special attention will be focused on the use of ion implantation followed by flash-lamp (FLA) annealing for the fabrication of heavily doped Ge. In contrast to conventional annealing procedures, rear-side FLA leads to full recrystallization of Ge and dopant activation independently of pre-treatment. The maximum carrier concentration is well above 10^20 cm-3 for n-type and above 10^21 for p-type doping. The recrystallization mechanism and the dopant distribution during rear-side FLA are discussed in detail. In this work, we report on the strong mid-IR plasmon absorption from heavily P-doped Ge thin films and superconductivity in Ga and Al doped Ge obtained by non-equilibrium thermal processing. The mid-IR plasmon spectral response at room temperature from those samples was characterized by means of Fourier transform infrared spectroscopy. It is proven that the position of the plasmonic resonance frequency signal can be tuned as a function of the P concentration.
Keywords: Ge, flash lamp annealing, doping
  • Invited lecture (Conferences)
    EMRS Fall Meeting 2017, 18.-21.09.2017, Warsaw, Poland

Publ.-Id: 26112 - Permalink


Influence of Nickel Catalyst Morphology on Layer-Exchange-Based Carbon Crystallisation of Ni/a-C Bilayers
Janke, D.; Hulman, M.; Wenisch, R.; Gemming, S.; Rafaja, D.; Krause, M.;
Metal-induced crystallisation with layer exchange is applied on Ni/C bilayer stacks deposited by three PVD techniques on SiO2. The layer stacks were deposited at room temperature by either ion beam sputtering, direct current magnetron sputtering or high-power impulse magnetron sputtering. The influence of the Ni morphology on the layer exchange degree aLE and the resulting graphitic ordering is studied by atomic force microscopy, Rutherford backscattering spectrometry and Raman spectroscopy. The initial RMS roughness of the Ni top layer varied with the deposition technique by a factor of 20, from 0.3 to 6.1 nm.
After annealing in UHV at up to 700°C, layer exchange was observed for all samples. Still, the layer exchange degree was affected by the roughness of the initial bilayer stack. The highest value of 96% was achieved for magnetron-sputtered samples, what is by ~35% higher than for the initially roughest Ni surfaces. Raman spectroscopy showed the formation of graphitic carbon, characterised by a strong 2D line, for all three bilayer stacks. The degree of graphitic ordering increased with decreasing Ni surface roughness.
Keywords: Metal-induced crystallisation of amorphous carbon, Layer exchange, Rutherford Backscattering Spectrometry, Raman spectroscopy

Publ.-Id: 26111 - Permalink


An Eulerian-Eulerian Computational Fluid Dynamic Approach to Predict the Boiling Process with New Developed Sub Models
Ding, W.; Krepper, E.; Hampel, U.;
Time averaged Eulerian multiphase approaches and the heat flux partitioning method is popular to be applied in the computational fluid dynamic simulations of wall boiling especially in the forced convective boiling. In such CFD simulations, many submodels for the bubble dynamics and the implementation of the bubble dynamics into the global models are particularly important. In order to get accurate bubble dynamics, a single bubble model for nucleate boiling based on the known microlayer theory was developed. The single bubble model consideres the dynamic bubble geometry, contact angle and bubble inclination angle in flow boiling at different time periods. The model is able to show the dependency of bubble departure diameter (lift off diameter) and frequency on the different physical quantities such as heat flux, liquid properties, sub-cooling temperature, design of channel (diameter, length), mass flow rate and so on. The implementation of this developed single bubble model requires an update of the conventional nucleation site activation and heat partitioning models in time averaged Eulerian multiphase approaches. The new activation approach considers a distribution of cavity sizes and their influence on the activation temperature. The dynamics of the bubbles generated from different size cavities at the same position differ from each other. The updated heat partitioning model assumes the heat flux at the evaporative area always as constant and equal to the known feed heat flux when the boiling system is in the steady state. With help of the multiple size group (MUSIG) model and a breakup and coalesce model, the time averaged Eulerian approach could simulate the bubble size distribution in a heated pipe. With the necessary calibration of the nucleation site density the comparisons between the calculation results and the Bartolomej’s experiments demonstrate the accuracy of this approach.
Keywords: Forced convective boiling, Eulerian multi-phase approach, microlayer, cavity group activation, heat partitioning
  • Contribution to proceedings
    17th International Topical Meeting on Nuclear Reactor Thermal hydaulics, 04.-08.09.2017, Xi'an, China
    17th International Topical Meeting on Nuclear Reactor Thermal hydaulics

Publ.-Id: 26110 - Permalink


A hypothesis of near critical heat flux (CHF-) based on minimum waiting time
Ding, W.; Krepper, E.; Hampel, U.;
Boiling is a very efficient heat transfer mechanism with a large heat transfer coefficient and it is widely found in industrial systems. However, boiling heat transfer is limited by the critical heat flux (CHF), also termed as boiling crisis, which may lower efficiency and jeopardize safety of heat transfer systems. The latter is of particular importance for the safe operation of nuclear light water reactors. A clear understanding of the basic mechanisms leading to CHF is still lacking. In this paper a new model for the quantitative prediction of the initiation of critical heat flux is derived from the bubble dynamics and heat fluxes in nucleate boiling. It incorporates effects of mutual bubble interaction and shear stress from bulk flow. The model was successfully validated with available experimental data from literature for both pool boiling and forced convective boiling and with that it can be very widely applied, both as a stand-alone model for heat transfer system design as well as a sub-model in computational fluid dynamics (CFD).
Keywords: Critical heat flux (CHF), boiling heat transfer, pool boiling, forced convective boiling, cavity activation
  • Contribution to proceedings
    17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, 04.-08.09.2017, Xi'an, China
    17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics

Publ.-Id: 26109 - Permalink


Bulk anaylsis of extraterrestrial samples using INAA at the research reactor FRM II
Li, X.; Leister, N.; Lierse Von Gostomski, C.; Merchel, S.; Gurlit, S.; Muszynski, A.; Szyszko, M.; Bischoff, A.;
Within the framework of a TUM-Kolleg Project between the TU München and the Otto-von-Taube-Gymnasium Gauting three ordinary chondrites from Germany (Cloppenburg [1], Oldenburg (Bissel), Benthullen), three HEDs from Oman and North-West-Africa (Dhofar 1675, NWA 2690, NWA 2698), one lunar and one martian Meteorite (NWA 7986, NWA 4925) were analyzed by instrumental neutron actication analysis (INAA). In Germany the FRM II is currently the most intensive neutron source offering different irradiation facilities and high and pure thermal neutron flux for INAA. In total, 45 elements including many REEs could be determined. A clear difference between chondrites and achondrites could be observed according to the element compositions. The high Ba-concentration in all samples is probably a result of weathering [2].
The martian meterorite has a high concentration of Fe (17.2%) compared to other achondrites. The moon sample has higher concentrations of REEs, but is apparently not a rock with a KREEP-signature.
[1] Storz, J. et al., this meeting. [2] Stelzner, T. et al., (1999) MAPS 34, 787-794.
Keywords: AMS, meteorite, REE, INAA, ICP-MS
  • Poster
    Paneth-Kolloquium, 10.-13.10.2017, Nördlingen, Deutschland

Publ.-Id: 26108 - Permalink


Photochemical Reduction of Non-fluorescent Tris(carbonato)uranyl(VI) Complex
Takao, K.; Tsushima, S.ORC
A uranyl ion usually shows characteristic green emission and photochemical reactions under UV irradiation, while tris(carbonato)uranyl(VI) complex is known to be exceptionally inert because of strong quenching through the bound carbonates. In this study, we report that tris(carbonato)uranyl(VI) was immediately reduced to the corresponding uranyl(V) species under presence of tetrahydroborate and UV irradiation.
  • Lecture (Conference)
    The 67th Conference of Japan Society of Coordination Chemistry, 16.-18.09.2017, Sapporo, Japan

Publ.-Id: 26106 - Permalink


Computational study on the interaction between Eu(III) and calmodulin
Tsushima, S.ORC; Mochizuki, Y.; Komeiji, Y.; Takao, K.
there is no abstract
  • Lecture (Conference)
    Atomic Energy Society of Japan 2017 Fall Meeting, 13.-15.09.2017, Sapporo, Japan

Publ.-Id: 26105 - Permalink


Theoretical study on Calmodulin binding with Ca(II) and Eu(III) ions
Tsushima, S.ORC; Mochizuki, Y.; Komeiji, Y.; Okuwaki, K.; Abe, T.; Mori, H.; Tanaka, S.
there is no abstract
  • Lecture (Conference)
    The 78th Japan Society of Applied Physics Meeting, 05.-08.09.2017, Fukuoka, Japan

Publ.-Id: 26104 - Permalink


Cloppenburg (H4-5) – first results of a new find
Storz, J.; Bischoff, A.; Degering, D.; Ebert, S.; Heinlein, D.; Jull, T.; Kontul, I.; Li., X.; Merchel, S.; Oberst, J.; Ott, U.; Pack, A.; Peters, S.; Petö, M. K.; Rugel, G.;
The Cloppenburg meteorite of 141 g was found March 15, 2017 by the facility manager of a school while collecting rocks for the school garden. The rock with a mean density of (3.33 ± 0.03) g/cm3 is a brecciated H-group ordinary chondrite (H4-5) with mean olivine and low-Ca pyroxene of Fa18.5±0.3 and Fs16.4±0.6, respectively. The breccia containing shock veins is weakly shocked (S3) and heavily weathered (W3). The occurrence of vivianite, the oxygen isotopes, and the Ba-enrichment (by INAA) indicate strong weathering in a very wet environment. Radionuclide data evaluation is still ongoing: Accelerator mass spectrometry (AMS) of 14C, will reveal the terrestrial age. An upper limit of the terrestrial age is yet set by low-level gamma-spectrometry in the Felsenkeller underground lab. No 22Na (t1/2=2.6 a) nor 44Ti (t1/2=59 a) could been detected within a counting time of 27 days, whereas 26Al (t1/2=0.7 Ma) was clearly identified. AMS of 10Be (t1/2=1.4 Ma) of ~18 dpm/kg confirms the high cosmic ray exposure age (CRE age) of (7.5 ± 0.4) Ma from noble gas mass spectrometry.
Keywords: AMS, cosmogenic nuclide, mass spectrometry, gamma-spectrometry, INAA
  • Poster
    Paneth-Kolloquium, 11.-13.10.2017, Nördlingen, Deutschland

Publ.-Id: 26103 - Permalink


Investigation of bioreactors by instrumented flow-following sensor particles
Reinecke, S.; Hampel, U.;
Instrumented flow-following sensor particles have been developed for investigation of hydrodynamic and biochemical processes chemical reactors and bioreactors, where standard measurement techniques are not applicable. The sensor particles allow autonomous long-term measurement of spatially distributed process parameters in the chemically and mechanically harsh environments of agitated industrial vessels. Each sensor particle comprises of an on-board measurement electronics that logs the signals of the embedded sensors. A buoyancy control unit enables automated taring to achieve neutral buoyancy of the sensor particles. Moreover, controlled floating of the sensor particles is possible to expose them for recovery from the fluid surface. The paper presents exemplary results from tests in an air-water column reactor, a pilot biogas digester and a waste water treatment plant.
Keywords: sensor particle, autonomous sensor, flow follower, hydrodynamics, bioreactor
  • Contribution to proceedings
    Sensor 2017, 30.05.-01.06.2017, Nürnberg, Deutschland
  • Lecture (Conference)
    Sensor 2017, 30.05.-01.06.2017, Nürnberg, Deutschland

Publ.-Id: 26102 - Permalink


The 2017 Magnetism Roadmap
Sander, D.; Valenzuela, S. O.; Makarov, D.; Marrows, C. H.; Fullerton, E. E.; Fischer, P.; McCord, J.; Vavassori, P.; Mangin, S.; Pirro, P.; Hillebrands, B.; Kent, A. D.; Jungwirth, T.; Gutfleisch, O.; Kim, C. G.; Berger, A.;
Building upon the success and relevance of the 2014 Magnetism Roadmap, this 2017 Magnetism Roadmap edition follows a similar general layout, even if its focus is naturally shifted, and a different group of experts and, thus, viewpoints are being collected and presented. More importantly, key developments have changed the research landscape in very relevant ways, so that a novel view onto some of the most crucial developments is warranted, and thus, this 2017 Magnetism Roadmap article is a timely endeavour. The change in landscape is hereby not exclusively scientific, but also reflects the magnetism related industrial application portfolio. Specifically, Hard Disk Drive technology, which still dominates digital storage and will continue to do so for many years, if not decades, has now limited its footprint in the scientific and research community, whereas significantly growing interest in magnetism and magnetic materials in relation to energy applications is noticeable, and other technological fields are emerging as well. Also, more and more work is occurring in which complex topologies of magnetically ordered states are being explored, hereby aiming at a technological utilization of the very theoretical concepts that were recognised by the 2016 Nobel Prize in Physics. Given this somewhat shifted scenario, it seemed appropriate to select topics for this roadmap article that represent the three core pillars of magnetism, namely magnetic materials, magnetic phenomena and associated characterization techniques, as well as applications of magnetism. While many of the contributions in this Roadmap have clearly overlapping relevance in all three fields, their relative focus is mostly associated to one of the three pillars. In this way, the interconnecting roles of having suitable magnetic materials, understanding (and being able to characterize) the underlying physics of their behaviour and utilizing them for applications and devices is well illustrated, thus giving an accurate snapshot of the world of magnetism in 2017. The article consists of 14 sections, each written by an expert in the field and addressing a specific subject on two pages. Evidently, the depth at which each contribution can describe the subject matter is limited and a full review of their statuses, advances, challenges and perspectives cannot be fully accomplished. Also, magnetism, as a vibrant research field, is too diverse, so a number of areas will not be adequately represented here, leaving space for further roadmap editions in the future. However, this 2017 Magnetism Roadmap article can provide a frame that will enable the reader to judge where each subject and magnetism research field stands overall today and which directions it might take in the foreseeable future. The first material focused pillar of the 2017 Magnetism Roadmap contains five articles, which address the questions of atomic scale confinement, 2D, curved and topological magnetic materials, as well as materials exhibiting unconventional magnetic phase transitions. The second pillar also has five contributions, which are devoted to advances in magnetic characterization, magneto-optics and magneto-plasmonics, ultrafast magnetization dynamics and magnonic transport. The final and application focused pillar has four contributions, which present non-volatile memory technology, antiferromagnetic spintronics, as well as magnet technology for energy and bio-related applications. As a whole, the 2017 Magnetism Roadmap article, just as with its 2014 predecessor, is intended to act as a reference point and guideline for emerging research directions in modern magnetism.
Keywords: magnetism, roadmap, magnetic materials, magneto-optics, spintronics, magnonics, magnetic memory

Publ.-Id: 26101 - Permalink


Mesoscale Dzyaloshinskii-Moriya interaction: geometrical tailoring of the magnetochirality
Volkov, O. M.; Sheka, D. D.; Kravchuk, V. P.; Gaididei, Y.; Rößler, U. K.; Faßbender, J.; Makarov, D.;
Crystals with broken inversion symmetry can host fundamentally appealing and technologically relevant periodical or localized chiral magnetic textures. The type of the texture as well as its magnetochiral properties are determined by the intrinsic Dzyaloshinskii-Moriya interaction (DMI), which is a material property and can hardly be changed. Here we put forth a method to create new artificial chiral nanoscale objects with tunable magnetochiral properties from standard magnetic materials by using geometrical manipulations. We introduce a mesoscale Dzyaloshinskii-Moriya interaction that combines the intrinsic spin-orbit- and extrinsic curvature-driven DMI terms and depends both on the material and geometrical parameters. The vector of the mesoscale DMI determines magnetochiral properties of any curved magnetic system with broken inversion symmetry. The strength and orientation of this vector can be changed by properly choosing the geometry. For a specific example of nanosized magnetic helix, the same material system with different geometrical parameters can acquire one of three zero-temperature magnetic phases, namely, phase with a quasitangential magnetization state, phase with a periodical state and one intermediate phase with a periodical domain wall state. The difference between equilibrium magnetization states for magnetic nanohelices with opposite geometrical chiralities put forth on a new simple measuring method of the DMI constant. Our approach paves the way towards the realization of a new class of nanoscale spintronic and spinorbitronic devices with the geometrically tunable magnetochirality.
Keywords: curvilinear magnetism, curved magnetic nanowires, micromagnetism

Publ.-Id: 26100 - Permalink


Magnetic coupling phenomena in curved nanomagnets
Makarov, D.;
Magnetic curvilinear objects possess new fundamental properties originating from the curvature-driven effects, leading to magnetochiral effects and topologically induced magnetization patterns. Recently, it was theoretically predicted that these effects come from the exchange-induced curvilinear interactions like anisotropy-like and chiral-like parts [R. Streubel et al., Magnetism in curved geometries (topical review), Journal of Physics D: Applied Physics 49 p. 363001 (2016)]. These recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this talk.
Keywords: curved magnetic thin films, curvilinear magnetism
  • Invited lecture (Conferences)
    Magnetic Coupling in Nanostructured Materials, 23.-25.10.2017, Rome, Italy

Publ.-Id: 26098 - Permalink


Spintronics of thin film granular antiferromagnets
Makarov, D.;
Antiferromagnets have the potential to revolutionize spintronics due to their inherently magnetic-field stable magnetic order and high-frequency operation. There are already great advances in the field especially when bulk antiferromagnets are considered. The application potential of antiferromagnets can be explored in full only if they will be prepared in the way to be compatible with a conventional microelectronic processing. This necessarily requires the use of (i) thin film antiferromagnets and (ii) discovery of methods to address the order parameter and its modifications all-electrically.
With respect to the first challenge it is necessary to understand modifications of the magnetic properties and magneto-electric responses of thin film antiferromagnets with respect to their bulk counterparts. Typically, thin films possess grainy morphology. Hence, to determine their application potential, questions regarding the change of the intergranular exchange, criticality behavior and switching of the order parameter need to be answered. This topic I will illustrate on the specific example of thin film magnetoelectric collinear antiferromagnet α-Cr2O3 studied using zero-offset Hall magnetometry and NV microscopy [1].
To address the second challenge it is required to develop transport-based techniques to harness the responses of thin film antiferromagnets. This task is difficult as minute uncompensated surface magnetization of antiferromagnets needs to be detected, which imposes strict requirements to the sensitivity of the method. I will outline our developments of zero-offset anomalous Hall magnetometry [2] applied to study the physics of conventional metallic IrMn and insulating magnetoelectric Cr2O3 antiferromagnets.
The fundamental understanding of the magnetic microstructure of magnetoelectric α-Cr2O3 thin films and the possibility to read-out its antiferromagnetic order parameter all-electrically enabled the entirely new recording concept where a magnetoelectric memory cell can be addressed without using a ferromagnet. With this approach, we opened an appealing field of purely antiferromagnetic magnetoelectric random access memory (AF-MERAM) [1]. The key performance parameters of the Cr2O3 based AF-MERAM will be highlighted.

[1] T. Kosub, M. Kopte, R. Hühne, P. Appel, B. Shields, P. Maletinsky, R. Hübner, M. O. Liedke, J. Fassbender, O. G. Schmidt, and D. Makarov, “Purely antiferromagnetic magnetoelectric random access memory”. Nature Communications 8, 13985 (2017).
[2] T. Kosub, M. Kopte, F. Radu, O. G. Schmidt, and D. Makarov, “All-Electric access to the magnetic-field-invariant magnetization of antiferromagnets”. Phys. Rev. Lett. 115, 097201 (2015).
Keywords: antiferromagnetic spintronics, magnetoelectric Memory
  • Invited lecture (Conferences)
    Workshop on antiferromagnetic spintronics, 25.-27.10.2017, Grenoble, France

Publ.-Id: 26097 - Permalink


Electronic proprioception
Makarov, D.;
Augmented reality gadgets are becoming common for our information intensive society assisting us to acquire and process the data. Although impressive in the realization and demonstrations, the obvious drawback of the state-of-the-art augmented and virtual reality devices relying on optical detection systems is their bulkiness, energy inefficiency and the stringent requirement for an operator to be at the line of sight of the device.
We envision that prospective augmented reality systems will strongly benefit from the recent developments in compliant on-skin electronics. The fabrication of highly conformable gadgets requires the realization of the electronic replica of the exteroceptive sensory system of humans as well as calls for the acquiring new perception skills beyond those prescribed by the evolution. The first crucial step towards the realization of this vision was accomplished with the development of interactive magnetosensitive skins [1-4].
Here, we present the first on-skin gadgets, which replicate our natural proprioceptive sensory ability of detecting the motion. Relying on this magnetically enabled electronic proprioception, we visualize the bodily motion and demonstrate the touchless manipulation of virtual objects for augmented reality systems. Those highly conformable interactive devices possess great potential to extend the portfolio of tasks, which can be performed in virtual or augmented reality. The integration of gadgets in imperceptible electronic skins will open not only exciting possibilities for business or gaming industry but is also beneficial for safety and security applications, where the somatic manipulation of objects, e.g. turning regulation knobs located in a restricted environment is undesirable or even prohibited.

1. M. Melzer et al., Nature Commun. 6, 6080 (2015).
2. M. Melzer et al., Adv. Mater. 27, 1274 (2015).
3. N. Münzenrieder et al., Adv. Electron. Mater. 2, 1600188 (2016).
4. D. Makarov et al., Appl. Phys. Rev. 3, 011101 (2016).
Keywords: magnetic field sensors, flexible electronics
  • Invited lecture (Conferences)
    NanoBioSensor Conference, 04.-05.09.2017, Dresden, Germany

Publ.-Id: 26096 - Permalink


H-T phase diagram of solid oxygen
Nomura, T.; Matsuda, Y. H.; Kobayashi, T. C.;
The comprehensive magnetic field–temperature (H-T) phase diagram of solid oxygen including the θ phase is discussed in the context of the ultrahigh-field measurement and the magnetocaloric effect (MCE) measurement. The problems originating from the short duration of the pulse field, nonequilibrium conditions and MCEs, are pointed out and dealt with. The obtained phase diagram manifests the entropy relation between the phases as Sθ ∼ Sα < Sβ << Sγ

Publ.-Id: 26095 - Permalink


Retention and multiphase transformation of selenium oxyanions during the formation of magnetite via ferrous hydroxide and green rust
Börsig, N.; Scheinost, A. C.; Shaw, S.; Schild, D.; Neumann, T.;
Environmental and health hazards of the trace element Se are mainly related to the presence of highly mobile Se oxyanion species (oxidation states +4 and +6). In this study, we investigate the immobilization of dissolved Se oxyanions during the formation process of magnetite by the progressive oxidation of an alkaline, anoxic Fe2+ system (pH 9.2). Up to initial concentrations of c(Se)0 = 10-3 mol/L (m/V ratio = 3.4 g/L), logRd values of xxxx demonstrate a strong retention of Se oxyanions during this mineral formation process. This Se immobilization is due to the reduction of Se(IV) or Se(VI), resulting in the precipitation of sparingly soluble Se compounds. By XRD analysis, these Se compounds were identified as crystalline elemental Se(0) that occurred in all coprecipitation products after the completed magnetite formation. The time-resolved analysis of the Se retention during the magnetite formation and detailed spectroscopic analyses (XPS, XAS) of the involved solid phases showed that the reduction takes place under the anoxic conditions in the early phase of the coprecipitation process by the interaction with iron(II) hydroxide and green rust. Both minerals represent the primary Fe(II)-containing precipitation products in the aquatic Fe2+ system and the precursor phases of the later formed magnetite. Spectroscopic and electron microscopic analysis prove that this early Se interaction leads to the formation of a nanoparticulate iron selenide phase [FeSe], which is oxidized and transformed into trigonal gray elemental Se during the progressive oxidation of the system. Regarding the retention behavior of Se, it is irrelevant whether the oxidation of the meta-stable iron oxide phases leads to the formation of magnetite only or also to other iron oxide phases like goethite. This reductive precipitation of Se induced by an interaction with metastable Fe(II)-containing iron oxide minerals should affect the mobility of Se oxyanions in contaminated environments, including the behavior of 79Se in the near-field of HLW repositories.
Keywords: selenite, selenate, selenide, iron oxide, reduction, oxidation, precipitation, immobilization, XPS, XAS, EXAFS

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  • Secondary publication expected from 05.07.2019

Publ.-Id: 26093 - Permalink


Permutation-blocking path-integral Monte Carlo approach to the static density response of the warm dense electron gas
Dornheim, T.; Groth, S.; Vorberger, J.; Bonitz, M.;
The static density response of the uniform electron gas is of fundamental importance for numerous applications.
Here we employ the recently developed ab initio permutation blocking path integral Monte Carlo (PB-PIMC) technique [T. Dornheim et al., New J. Phys. 17, 073017 (2015)] to carry out extensive simulations of the harmonically perturbed electron gas at warm dense matter conditions. In particular, we investigate in detail the validity of linear response theory and demonstrate that PB-PIMC allows us to obtain highly accurate results for the static density response function and, thus, the static local field correction. A comparison with dielectric approximations to our new ab initio data reveals the need for an exact treatment of correlations. Finally, we consider a superposition of multiple perturbations and discuss the implications for the calculation of the static response function.
Keywords: warm dense matter, quantum monte carlo, response function, electron gas, fermion sign problem, linear response
  • Physical Review E 96(2017), 023203

Publ.-Id: 26091 - Permalink


Optical contrast formation in ta-C films by ion implantation
Berova, M.; Sandulov, M.; Tsvetkova, T.; Szekeres, A.; Terziyska, P.; Kitova, S.; Böttger, R.; Bischoff, L.;
Tetrahedral amorphous carbon (ta-C) thin films (d ~ 40 nm), deposited by filtered cathodic vacuum arc (FCVA) method, have been implanted with Ga+ ions with energy 20 keV and ion fluences 3xE14 and 3xE15 cm-2. The implantation induced modification of the films structure is reflected in a considerable change of their optical properties, best manifested by a significant shift of the optical absorption edge to lower photon energies as obtained from optical measurements. This shift is accompanied by a considerable increase of the absorption coefficient in the photon energy range (0.5 ÷ 3.0 eV). The observed effects could be attributed both to additional defect generation and increased graphitization, as well as by gallium colloids formation. The optical contrast thus obtained (between implanted and unimplanted film material) could be of use in the area of high-density optical data storage using focused Ga+ ion beams.
Keywords: ta-C films, Ga implantation, optical properties
  • Revue Roumaine de Chimie 62(2017)10, 761-765

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Publ.-Id: 26090 - Permalink


CFD-simulation of different bubbly flow situations applying the Euler-Euler framework
Krepper, E.; Lucas, D.; Rzehak, R.;
A widely used approach to model two-phase bubbly flows for industrial applications is the Eulerian two-fluid framework of interpenetrating continua. The loss of details caused by the averaging procedure has to be compensated by consideration of additional closure relations. These concern the momentum exchange between the phases, the effect of the bubbles on liquid turbulence and bubble breakup & coalescence. A set of best available sub models was assembled (Rzehak and Krepper, 2013, 2015). To ensure the predictive capabilities it has to be shown that this model framework is able to describe different flow situations without any changes of model parameters.
The present contribution starts with validation work on upward turbulent bubbly flow in a vertical tube at the MTLoop facility using the wiremesh technique. A second step is the extension to counter-current and co-current downward flow at ROFEX using fast X-Ray tomography (Krepper et al. 2016). Both facilities were operated in Helmholtz - Zentrum Dresden-Rossendorf. Data on the cross sectional distribution of gas volume fraction, of gas and liquid velocity and on bubble size distributions were gained.
The presentation shows the capability of an unified framework of closure relationships to describe different flow situations.
Keywords: CFD, momentum exchange, bubble induced turbulence, fixed polydispersed flow
  • Lecture (Conference)
    The 3rd International Conference on Numerical Methods in Multiphase Flows, ICNMMF-III, 26.-29.06.2017, Tokyo, Japan

Publ.-Id: 26089 - Permalink


CFD analysis on experiments of bubbly flow in a tube with an obstacle
Krepper, E.; Neumann, M.; Lucas, D.;
Two phase adiabatic air/water flow in a vertical tube with an inner diameter of 54 mm equipped with an inner obstacle was investigated. Experiments are conducted for a wide range of superficial gas and liquid velocities in bubbly flow regime. Flow obstacles, namely a ring shaped diaphragm and a half-moon shaped diaphragm, are used for generation of three-dimensional flow fields. Besides conventional measurement techniques an ultrafast X-ray tomography scanner ROFEX, which was developed by HZDR, are applied. ROFEX determines gas distributions, bubble velocities and bubble sizes (Hampel et al. 2013, 2016).
The experiments were used to analyze the capability of the actual CFD based on the Euler/Eulerian approach. The CFD calculations were performed as pre-test simulations. Measured results for half-moon shaped diaphragm tests were available short before publishing the manuscript and shown with the calculations. Most of the values and at least the tendencies could be predicted with good agreement to measurements. Reasons for deviations are discussed in the paper.
CFD simulation enables the investigation of single components of the model approach. So the distribution of the bubble forces and the strength and location of single breakup&coalescence mechanisms can be analyzed and checked for plausibility.
Keywords: bubbly flow, experiments, CFD, momentum exchange, bubble induced turbulence, bubble breakup & coalescence
  • Contribution to proceedings
    The 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17), 03.-08.09.2017, Xi'an, China
  • Lecture (Conference)
    The 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17), 03.-08.09.2017, Xi'an, China

Publ.-Id: 26088 - Permalink


Concepts of CFD modelling of boiling towards CHF
Krepper, E.; Ding, W.;
Boiling is an effective heat transfer mechanism which plays an important role in many industrial applications. The heat transfer capability is limited by the critical heat flux (CHF). The conditions for CFX have to be avoided in any cases. The simulation of these not yet fully understood phenomena has not yet reached an acceptable maturity.
The presentation describes actual concepts of simulation of boiling beginning with the heat flux partitioning approach. In recent developments the bubble size distribution was considered. Concepts for describing CHF are presented.
Keywords: Boiling, CFD, Heat flux partitioning, bubble population balance, critical heat flux
  • Lecture (Conference)
    28th Meeting of the German CFD Network of Competence, 07.03.2017, Garching, Deutschland

Publ.-Id: 26087 - Permalink


Substitution mechanisms in In, Au, and Cu-bearing sphalerites studied by X-ray absorption spectroscopy of synthetic and natural minerals
Filimonova, O. N.; Trigub, A. L.; Tonkacheev, D. E.; Nickolsky, M. S.; Kvashnina, K. O.; Chareev, D. A.; Chaplygin, I. V.; Kovalchuk, E. V.; Lafuerza, S.; Tagirov, B. R.;
Processing of Zn ore accounts for >95% of production of In - a "critical" metal which is widely used in the high-tech electronics. The main source of In is sphalerite (Zn, Fe)S which also can host industrial concentrations of Au. Here we use X-ray absorption spectroscopy to investigate the coupled chemistry of In and Au in synthetic sphalerite crystals - analogues of natural minerals. The concentrations of In and Au were found to correlate with each other and reached 0.5 wt% in crystals synthesized at 850 °C. Both metals are homogeneously distributed within the sphalerite matrix. However, their positions within the mineral are different. In accord with X-ray absorption near edge structure (XANES) spectroscopy the formal oxidation state of these elements is +3 (In) and +1 (Au). Analysis of extended X-ray absorption fine structure (EXAFS) spectra revealed that In replaces Zn in the structure of sphalerite. The In-ligand distance increases by 0.12 Å and 0.09-0.10 Å for the 1st and 2nd coordination spheres, respectively, in comparison with pure ZnS. The In-S distance in the 3rd coordination sphere is close to the one of pure sphalerite. The In K-edge and Au L3-edge XANES and EXAFS spectra suggest that there is no In-Au clustering. Gold in sphalerite is coordinated with 2.5±0.3 S atoms at Au-S distance of 2.35±0.01 Å in the 1st coordination sphere, whereas distant coordination spheres have disordered nature.
Our data suggest that at least two different forms of Au are present in sphalerite. At high Au concentrations (0.03-0.5 wt%) the nanosized Au2S clusters predominate, probably with small admixture of the Au solid solution characterized by higher Au-S distance. Alike Au, the other 1st group metals (Me) Cu and Ag, which often are present in high (tenths ppm to wt%) concentrations in sphalerite, can form nanosized Me-S clusters with only traces (ppm level) of metal in the solid solution state.

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  • Secondary publication expected from 04.03.2020

Publ.-Id: 26086 - Permalink


Radioimmunkonjugate für die theragnostische Anwendung an Prostata-Stammzellantigen-exprimierenden Tumoren
Oertel, F.; Arndt, C.; Feldmann, A.; Bergmann, R.; Steinbach, J.; Pietzsch, H.-J.; Bachmann, M.;
Ziel: Das Prostata-Stammzellantigen (PSCA) wird auf der Zelloberfläche von über 80% der Prostatatumore (PCa) und deren Knochenmetastasen exprimiert. Aus diesem Grund wird es häufig als Zielstruktur sowohl für die Radioimmuntherapie (RIT) als auch für molekulare Bildgebungstechniken von PCa in der Nuklearmedizin (Positronen-Emissions-Tomographie (PET) und Einzelphotonen-Emissionscomputertomographie (SPECT)) verwendet. Für die jeweiligen Anwendungsgebiete wurden Radioimmunkonjugate basierend auf monoklonalen anti-PSCA-Antikörpern (mAk, 150 kDa) und von diesen abgeleitete Einzelkettenantikörperfragmente („single-chain Fragment variable“ (scFv), 35 kDa) hergestellt. In Kombination sollen diese Radioimmunkonjugaten als therapeutisches und diagnostisches Instrument für PSCA-positive PCa Anwendung finden.
Methoden und Ergebnisse: Zwei unterschiedliche anti-PSCA mAk-Klone, RD1 und RD2 genannt, sowie davon abgeleitete scFvs wurden hergestellt, über Affinitätschromatographie gereinigt und deren Bindungseigenschaften an PSCA-positiven PC3-Zellen mittels Durchflusszytometrie ermittelt. Die unmarkierten mAk-Klone RD1 und RD2 zeigten hohe Affinitäten, mit Dissoziationskonstanten von 10 und 6 nM. Für die scFvs von RD1 und RD2 wurden geringere Affinitäten von 170 und 98 nM bestimmt. Die beiden mAk-Klone wurden anschließend mit dem bifunktionellen Chelator p-SCN-Bn-CHX-A’’-DTPA, die scFv-Antikörper hingegen mit p-SCN-Bn-NOTA konjugiert. Für alle Konstrukte wurde mittels MALDI-TOF-Massenspektrometrie eine durchschnittliche Anzahl von drei Chelator-Einheiten je Antikörpermolekül gemessen. Anschließend wurden die mAk-Konjugate für eine mögliche RIT-Anwendung mit Lutetium-177 und die scFv-Konjugate für eine mögliche PET-Bildgebung mit Kupfer-64 radiomarkiert. Des Weiteren wurden scFv-Antikörper auch direkt mit Technetium-99m mit Hilfe eines Tricarbonyl-Präkursor an ihrem Hexahistidin-Tag für eine mögliche SPECT-Bildgebung markiert. Für alle radiomarkierten Konjugate wurde eine radiochemische Reinheit von über 95% (radio-Dünnschichtchromatographie) erzielt. Nachfolgende In-vitro-Studien an PC3-PSCA-Zellen zeigten, dass die Bindungseigenschaften zum PSCA erhalten bleiben.
Ausblick: An entsprechenden Tumormaus-Modellen wird gegenwärtig geprüft, ob die positiven in-vitro Resultate für die hergestellten Radioimmunkonjugate bestätigt werden können.
  • Poster
    GdCh Wissenschaftsforum Chemie 2017, 10.-14.09.2017, Berlin, Deutschland

Publ.-Id: 26085 - Permalink


Radioimmunoconjugates for theragnostics of Prostate Stem Cell Antigen (PSCA)-expressing tumors
Oertel, F.; Arndt, C.; Feldmann, A.; Bergmann, R.; Steinbach, J.; Bachmann, M.; Pietzsch, H.-J.;
Aim: Advances in molecular engineering have led to the development of a multiplicity of antibody fragments with variations in molecular size. With respect to tumor targeting, the molecular size evidently determines the tumor uptake and pharmacokinetics. Consequently, they are proposed for different applications: small radiolabeled antibody fragments, such as single-chain variable fragments (scFv, 25-35 kDa) for tumor imaging and large full-size monoclonal antibodies (mAbs, 150 kDa) for radioimmunotherapy. Here, mAbs and thereof derived scFvs were produced that are directed against the prostate stem cell antigen (PSCA). Due to its overexpression on the surface of various tumor types, including prostate cancer and its metastases, it is proposed as a promising tumor target structure. Both antibody-based targeting molecules might provide a combinatory tool for theranostics of PSCA-positive prostate cancer.

Methods: In this study, two different anti-PSCA mAb clones, RD1 and RD2, as well as their respective anti-PSCA scFvs were produced and compared with regard to their binding properties towards PSCA, using flow cytometry analysis. The anti-PSCA mAbs were conjugated with the chelating agent p-SCN-CHX-A’’-DTPA, measured by MALDI-TOF, and subsequently radiolabeled with lutetium-177, whereas the scFvs were radiolabeled with technetium-99m on their histidine-tag. Thereafter, all radiolabeled conjugates were characterized by thin-layer chromatography, and regarding binding properties on PC3-PSCA cells in vitro.

Results: The non-radiolabeled anti-PSCA mAbs RD1 and RD2 showed a high affinity, with dissociation constants of 10 and 6 nM, respectively. The corresponding scFvs of RD1 and RD2 exhibit a lower affinity, with Kd-values of 170 and 98 nM. Both full mAbs were conjugated with about three CHX-A’’-DTPA. This conjugation had no influence on binding affinity towards the PSCA. Subsequent radiolabeling of the mAb-conjugates and scFvs could be performed with high radiochemical purity (> 95%) with preserving their binding properties to the PSCA.

Conclusion: Full-size mAbs and scFvs that target the tumor antigen PSCA were successfully produced and radiolabeled. The in vitro characterization showed promising results to proceed with studies on tumor mouse models.
  • Poster
    The 22nd International Symposium on Radiopharmaceutical Sciences (ISRS 2017), 14.-19.05.2017, Dresden, Deutschland

Publ.-Id: 26084 - Permalink


THz-driven dynamics probed by time-resolved ARPES – the high repetition rate opportunity
Deinert, J.-C.ORC; Green, B. W.; Kovalev, S.; Gensch, M.
Terahertz radiation offers unique control of low-energy excitations in matter. Fundamental modes, such as molecular rotations, lattice vibrations, electron and ion motion or spin precession can be coherently controlled on an ultrafast timescale, while parasitic electronic excitations are suppressed, because of the low THz photon energy.
The THz-induced effects, e.g. phase transitions in solids or modifications of chemical reactions are intrinsically connected to changes in the electronic structure of the material. The natural way to directly probe these changes is time- and angle-resolved photoelectron spectroscopy (tr-ARPES).
The main challenges which have impeded the experimental realization are:
availability of high field and high repetition rate THz source
knowledge and control of interaction of photo- electrons with THz field (“streaking”)
Accelerator-based THz sources like FLASH and TELBE provide ideal conditions for establishing feasibility and dynamic range of THz-pump tr-ARPES.
Keywords: Terahertz, Photoelectron Spectroscopy, pump-probe, ultrafast, condensed matter
  • Poster
    Future of science at FLASH - Opportunities with a cw XUV and soft X-ray FEL, 25.09.2017, Hamburg, Deutschland

Publ.-Id: 26083 - Permalink


Effective proton-neutron interaction near the drip line from unbound states in 25,26F
Vandebrouck, M.; Lepailleur, A.; Sorlin, O.; Aumann, T.; Caesar, C.; Holl, M.; Panin, V.; Wamers, F.; Stroberg, S. R.; Holt, J. D.; de Oliveira Santos, F.; Alvarez-Pol, H.; Atar, L.; Avdeichikov, V.; Beceiro-Novo, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Bogner, S. K.; Boillos, J. M.; Boretzky, K.; Borge, M. J. G.; Caamano, M.; Casarejos, E.; Catford, W.; Cederkall, J.; Chartier, M.; Chulkov, L.; Cortina-Gil, D.; Cravo, E.; Crespo, R.; Datta Pramanik, U.; Diaz Fernandez, P.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estrade, A.; Farinon, F.; Fraile, L. M.; Freer, M.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Gibelin, J.; Golubev, P.; Göbel, K.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Heinz, A.; Henriques, A.; Hergert, H.; Hufnagel, A.; Ignatov, A.; Johansson, H. T.; Jonson, B.; Kahlbow, J.; Kalantar-Nayestanaki, N.; Kanungo, R.; Kelic-Heil, A.; Knyazev, A.; Kröll, T.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lindberg, S.; Machado, J.; Marganiec, J.; Marques, F. M.; Movsesyan, A.; Nacher, E.; Najafi, M.; Nikolskii, E.; Nilsson, T.; Nociforo, C.; Paschalis, S.; Perea, A.; Petri, M.; Pietri, S.; Plag, R.; Reifarth, R.; Ribeiro, G.; Rigollet, C.; Röder, M.; Rossi, D.; Savran, D.; Scheit, H.; Schwenk, A.; Simon, H.; Syndikus, I.; Taylor, J. T.; Tengblad, O.; Thies, R.; Togano, Y.; Velho, P.; Volkov, V.; Wagner, A.; Weick, H.; Wheldon, C.; Wilson, G.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M.; Zilges, A.; Zuber, K.;
Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The 26F nucleus, composed of a deeply bound p0d5=2 proton and an unbound n0d3=2 neutron on top of an 24O core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a Jp = 1+ - 4+1 multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The Jp = 1+1 ; 2+1 ; 4+1 bound states have been determined, and only a clear identification of the Jp = 3+ 1 is missing.
Keywords: Coulomb dissociation radioactive beam

Publ.-Id: 26082 - Permalink


Bio-recycling of metals: Recycling of technical products using biological applications
Pollmann, K.; Kutschke, S.; Matys, S.; Raff, J.; Hlawacek, G.; Lederer, F. L.;
The increasing demand of different metals as a consequence of the development of new technologies, especially in the so called “low carbon technologies” require the development of innovative technologies that enable an environmentally friendly metal recovery. Current recycling rates are very low due to the increasing complexicity of products and the low content of certain critical elements. Therefore efforts have to be done on efficient recycling methodologies in order to enable a circular economy. Modern biotechnologies can contribute to solve some of the problems related to metal recycling. These approaches use natural properties of organisms, bio-compounds, and biomolecules to interact with minerals, materials, metals, or metal ions such as surface attachment, mineral dissolution, transformation, and metal complexation. The article presents some recent developments in the fields of bioleaching, biosorption, bioreduction, and bioflotation and their use for metal recovery from electronic devices, waste material, and industrial effluents.
Keywords: Biohydrometallurgy, biomining, bioleaching, biosorption, bioflotation, bioreduction, metal recovery, recycling, critical metals

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Publ.-Id: 26081 - Permalink


Investigation of the superconducting gap structure in κ-(BEDT-TTF)2Cu(NCS)2 and κ-(BEDT-TTF)2Cu[N(CN)2]Br by means of thermal-conductivity measurements
Kühlmorgen, S.; Schönemann, R.; Green, E. L.; Müller, J.; Wosnitza, J.;
We report temperature-dependent thermal-conductivity, κ, measurements on the layered quasi-two-dimensional organic superconductors κ-(BEDT-TTF)2Cu(NCS)2 and κ-(BEDTTTF)2Cu[N(CN)2]Br down to 160 mK. The results for κ-(BEDT-TTF)2Cu(NCS)2 may be consistent with a nodal superconducting (SC) gap structure as indicated by a nonnegligible remnant linear contribution when κ /T α T2 is extrapolated to T = 0. For κ-(BEDT-TTF)2Cu[N(CN)2]Br, contrary to expectations, higher κ values are observed in the superconducting regime as compared to the normal, high-field state evidencing a dominant phonon contribution to κ in the superconducting state. The strong increase of κ in the normal state below Tc for both samples indicates strong electron–phonon scattering. Our results highlight the need for thermal-conductivity measurements performed down to significantly lower temperatures to determine the symmetry of the SC gap.

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  • Secondary publication expected

Publ.-Id: 26080 - Permalink


Experimental Assessment of a Flat Sandwich-Like Self-Powered Detector for Nuclear Measurements in ITER Test Blanket Modules
Raj, P.; Angelone, M.; Döring, T.; Eberhardt, K.; Fischer, U.; Klix, A.; Schwengner, R.;
Neutron and gamma flux measurements in designated positions in the test blanket modules (TBM) of ITER will be important tasks during its campaigns. Investigations on self-powered detectors (SPD) - a type of flux monitors, are undertaken in the framework of an ongoing project on development of nuclear instrumentation for European ITER TBMs. This paper reports the findings of experiments performed with an SPD in flat sandwich-like geometry. A detector with vanadium emitter is chosen for preliminary studies. Its irradiation in a thermal neutron field gives a proof of the principle of flat SPDs. It is further irradiated in the mixed neutron-gamma field of a 14 MeV neutron generator and a bremsstrahlung photon field. The detector signals are
proportional to the incident fluxes, deeming it suitable for flux monitoring. Whereas both neutrons and gammas can be detected with appropriate optimization of geometries, materials and sizes of the components, the present design is more sensitive to gammas than fast neutrons. Based on the measured sensitivities of the SPD, its response under TBM conditions is predicted.
Keywords: test blanket modules, neutron flux, gamma flux monitors, elf-powered detectors

Publ.-Id: 26079 - Permalink


Quasi-two-dimensional Fermi surfaces with localized f electrons in the layered heavy-fermion compound CePt2In7
Götze, K.; Krupko, Y.; Bruin, J. A. N.; Klotz, J.; Hinlopen, R. D. H.; Ota, S.; Hirose, Y.; Harima, H.; Settai, R.; Mccollam, A.; Sheikin, I.;
We report measurements of the de Haas–van Alphen effect in the layered heavy-fermion compound CePt2In7 in high magnetic fields up to 35 T. Above an angle-dependent threshold field, we observed several de Haas–van Alphen frequencies originating from almost ideally two-dimensional Fermi surfaces. The frequencies are similar to those previously observed to develop only above a much higher field of 45 T, where a clear anomaly was detected and proposed to originate from a change in the electronic structure [M. M. Altarawneh et al., Phys. Rev. B 83, 081103 (2011)]. Our experimental results are compared with band structure calculations performed for both CePt2In7 and LaPt2In7, and the comparison suggests localized f electrons in CePt2In7. This conclusion is further supported by comparing experimentally observed Fermi surfaces in CePt2In7 and PrPt2In7, which are found to be almost identical. The measured effective masses in CePt2In7 are only moderately enhanced above the bare electron mass m0, from 2m0 to 6m0.

Publ.-Id: 26078 - Permalink


Preparation of 18F-labeled building blocks for peptide conjugation using the "minimalist" approach
Omrane, M. A.; Zlatopolskiy, B. D.; Urusova, E.; Mamat, C.; Feni, L.; Neundorf, I.; Neumaier, B.;
Recently, the “minimalist” protocol for radiofluorination was reported. This method allowed to prepare labeled probes from only [18F]F– and onium salts without base and other additives avoiding time-consuming azeotropic drying. The aim of this work was the implementation of the “minimalist” approach for the preparation of radiofluorinated building blocks via SN2. [18F]Fluoride was eluted from a QMA cartridge with an appropriate azetidinium or onium salt precursor of [18F]AFP, [18F]BFP and 5-[18F]FDR in MeOH. MeOH was evaporated at 55°C (550 mbar) within 2–3 min. MeCN was added and the resulting solutions were heated to give the corresponding 18F-labeled products. Protected 5-[18F]FDR was purified by SPE and thereafter deprotected under acidic conditions. Finally, reaction conditions for the conjugation of 5-[18F]FDR to aminooxy-functionalized peptides via chemoselective oxime ligation were optimized. [18F]F– was eluted from an anion exchange resin almost quantitatively. Under optimized conditions appropriately protected 5-[18F]FDR as well as [18F]AFP and [18F]BFP were prepared from the corresponding 3-N,N,N-trimethylammoniumalkyl(aryl)sulfonyl and azetidinium precursors in RCYs of up to 70%, 90% and 91% (determined by radio-HPLC analysis of the crude product), respectively. After SPE purification 5-[18F]FDR was obtained in 41% RCY (EOB) and excellent RCP >99% after deprotection with 1 m HCl (110 °C, 12 min) . The amount of d-ribose (60–80 μg/batch), a competitor in subsequent oxime ligation, was low enough to allow an efficient conjugation of 5-[18F]FDR with aminooxy-functionalized peptides. The corresponding conjugates were prepared in RCYs of up to 91%. The SN2 radiofluorination under “minimalist” conditions is well suited for the fast production of versatile 18F-labeled building blocks. The positively charged trimethylammonium “tag” of the 5-[18F]FDR precursor enables its simple separation from the labeled product using SPE. The prosthetic group was sufficiently pure for the subsequent labeling of peptides.
  • Poster
    22nd International Symposium on Radiopharmaceutical Sciences (ISRS 2017), Dresden, 14.-19.05.2017, Dresden, Deutschland
  • Open Access LogoJournal of Labelled Compounds and Radiopharmaceuticals 60(2017)S1, S261
    DOI: 10.1002/jlcr.3508

Publ.-Id: 26077 - Permalink


Evaluation of Ba/Ra Polyoxopalladates for Radiopharmaceutical Applications
Gott, M.; Yang, P.; Kortz, U.; Pietzsch, H.-J.; Steinbach, J.; Mamat, C.;
Alpha particles show great promise for therapeutic applications due to their high rate of linear energy transfer over short path lengths. Radium-223 has excellent decay properties but, a major hurdle for its use is the development of a stable chelator for delivery to the tumor site. Work is underway testing polyoxopalladates, as a novel subclass of polyoxometalates (POMs), to complex barium and radium and establish the feasibility of their radiopharmaceutical use. Nonradioactive BaPd15 POMs were produced by the reported literature method and characterized by NMR, TLC, and HPLC. Radioactive [133Ba, 224Ra]BaPd15 POMs were prepared similarly with either [133Ba]BaCl2 or [224Ra]RaCl2 spiked into the solution prior to heating. Characterization was performed by NMR, RadioTLC, and HPLC. Chromatographic separations were tested using Dowex-50 and Sephadex G-15 to purify the POM product. Dialysis studies were carried out to determine the stability of the [133Ba]BaPd15. Incubation studies with rat serum were performed to explore their biological stability. The POMs were easily prepared in a one-pot reaction and characterized by 1H and 13C NMR. TLC and HPLC were performed to determine the percent of incorporated radionuclide. Cation exchange chromatography with Dowex 50-X8 removed free [133Ba]Ba2+ to non-detectable levels in the product. Size exclusion chromatography with Sephadex G-15 separated the BaPd15 product (eluted first) from the bulk excess of acetate buffer and phenylarsonic acid. Dialysis studies showed measurable quantities of 133Ba in solution after 1 hour and ~ 10% of the radionuclide had escaped after 24 hours. Serum studies indicated the POMs had affinity for serum proteins quickly upon contact with the serum. The results of this study demonstrate the development of radioactive [133Ba, 224Ra]BaPd15 POMs. Stability studies indicated that these POMs quickly began to decompose, significantly so after 24 hours. Additionally, incubation studies with rat serum demonstrated an affinity for serum proteins. For these reasons, these POMs are unsuitable for radiotherapeutic use.
Keywords: Polyoxometalates, Alpha-therapy, Radium
  • Poster
    22nd International Symposium on Radiopharmaceutical Sciences (ISRS 2017), Dresden, 14.-19.05.2017, Dresden, Deutschland
  • Open Access LogoJournal of Labelled Compounds and Radiopharmaceuticals 60(2017)S1, S559
    DOI: 10.1002/jlcr.3508

Publ.-Id: 26076 - Permalink


Synthesis of a Cu-Filled Rh17S15 Framework: Microwave Polyol Process Versus High-Temperature Route
Roslova, M.; Golub, P.; Opherden, L.; Ovchinnikov, A.; Uhlarz, M.; Baranov, A. I.; Prots, Y.; Isaeva, A.; Coduri, M.; Herrmannsdörfer, T.; Wosnitza, J.; Doert, T.; Ruck, M.;
Metal-rich, mixed copper−rhodium sulfide Cu3−δRh34S30 that represents a new Cu-filled variant of the Rh17S15 structure has been synthesized and structurally characterized. Copper content in the [CuRh8] cubic cluster was found to vary notably dependent on the chosen synthetic route. Full site occupancy was achieved only in nanoscaled Cu3Rh34S30 obtained by a rapid, microwave-assisted reaction of CuCl, Rh2(CH3CO2)4 and thiosemicarbazide at 300 °C in just 30 min; whereas merely Cu-deficient Cu3−δRh34S30 (2.0 ≥ δ ≥ 0.9) compositions were realized via conventional high-temperature ceramic synthesis from the elements at 950 °C. Although Cu3−δRh34S30 is metallic just like Rh17S15, the slightly enhanced metal content has a dramatic effect on the electronic properties. Whereas the Rh17S15 host undergoes a superconducting transition at 5.4 K, no signs of the latter were found for the Cu-derivatives at least down to 1.8 K. This finding is corroborated by the strongly reduced density of states at the Fermi level of the ternary sulfide and the disruption of long-range Rh−Rh interactions in favor of Cu−Rh interactions as revealed by quantum-chemical calculations.

Publ.-Id: 26075 - Permalink


Novel Functionalized Calixarenes as Host Molecules for Complexation with Alkaline Earth Metals
Steinberg, J.; Gott, M.; Pietzsch, H.-J.; Steinbach, J.; Mamat, C.;
Alpha-emitting radionuclides (e.g. radium-223, 224) are of high interest for cancer therapy, but currently, no stable complexing agent for radium is known. Moderate stability constants have been described for complexes of alkaline-earth metal ions with calixarenes, crown and aza crown ethers [2, 3]. By combining calixarenes with crown and aza crown ethers as well as functionalizing the remaining calixarene hydroxyl groups, higher stability constants may be achieved. In this study, we synthesized and evaluated new functionalized calixarenes as host molecules for radium. 1,3 single-bridged crowns were selectively introduced on the lower rim of 4-tert-Butylcalix[4]arene by alkylation with tosylated crown ethers or by acylation and sequential amination with aza crown ethers. The remaining phenolic hydroxyl groups were functionalized by acylation and sequential amination to prepare acetic acid amide and hydroxyl amide derivatives. The complexation was carried out by vortexing the ligand in chloroform with an aqueous BaCl2-solution as surrogate for Ra for 10 min. The barium complex was isolated from the organic layer and characterization was performed by NMR. The barium-133 and radium-224 calixcrowns were prepared similarly and stability studies performed by TLC and HPLC. 1,3-bridged crown and calix(aza)crown ethers were obtained in good yields (53 and 58%, respectively) and acetic acid amide and hydroxyl amide calixcrown derivatives were successfully prepared with yields of 66-82%. Barium was incorporated into the calixarene compounds, isolated by a two-phase extraction and the structure confirmed by NMR. Synthesis and stability of the radioactive complexes will be reported. Future studies will incorporate a targeting moiety on the upper ring. Several novel, functionalized calixarene compounds were prepared and initial complexation studies were performed with nonradioactive barium. The resulting complexes were checked by NMR and the procedure was transferred to radioactive barium-133 and radium-224. Complexation and stability was demonstrated by radiographic imaging of the developed TLC plates. These complexes show great promise for application to cancer therapy.
Keywords: Alpha-therapy, Radium, Calixarenes
  • Poster
    22nd International Symposium on Radiopharmaceutical Sciences (ISRS 2017), Dresden, 14.-19.05.2017, Dresden, Deutschland
  • Open Access LogoJournal of Labelled Compounds and Radiopharmaceuticals 60(2017)S1, S488
    DOI: 10.1002/jlcr.3508

Publ.-Id: 26074 - Permalink


Combining in situ synchrotron X-ray diffraction and X-ray radiography to study the dendritic growth in Ga–In alloys
Shevchenko, N.; Grenzer, J.; Keplinger, O.; Rack, A.; Cantelli, V.; Eckert, S.;
Dendrites are common microstructures that are formed during industrial casting or welding. The processes involved in the formation of different dendrite morphologies and the orientation selection during dendritic growth are rather complex and still far from being fully understood [1-3]. In this work, in situ synchrotron X-ray radiography and diffraction methods have been combined to study the evolution of dendritic microstructures during the solidification of Ga - In alloys. The in situ directional solidification experiments were performed at the ID19 and BM20 beamlines (ESRF, France) at a high spatial resolution of < 1 µm.
Solidification processes are affected by natural convection as soon as instable density stratification arises in the melt. Melt flow induces various effects on the dendrite and grain morphology primarily caused by the convective transport of the solute. Usually, the morphologies of these dendrites differ from those developing under purely diffusive condition. Our observations show a facilitation of the growth of primary trunks or lateral branches, a suppression of side branching, dendrite remelting and fragmentation [4]. The final microstructure reveals dendrites with random and complicated morphologies.
The flow-induced variations of the local solute concentration may result in the changes of dendrite crystal orientations. According to theoretical predictions, the dendrite growth directions should not follow necessarily low indexed crystallographic directions [1]. Therefore coupling of in situ X-ray imaging with X-ray diffraction provides additionally information of the crystallographic orientation of the growing dendrites. Our measurements show that majority of the Indium dendrites grow along the <110> orientation, typically observed in body-centered metals. The analysis of the diffraction patterns obtained from the complex dendritic structures shows that a further improvement towards a 3D imaging experiment is needed. These first results demonstrate that the combination of these X-ray techniques can provide new data about the solidification processes and help to validate microstructural solidification models.
This work is financially supported by the Helmholtz Association “LIMTECH”.
Keywords: Dendrites, solidification, in situ synchrotron radiography, X-ray diffraction
  • Poster
    ESRF User Meeting, 06.-08.02.2017, Grenoble, France

Publ.-Id: 26073 - Permalink


Detection of Auger Electron Induced Strand Breaks on Plasmid DNA Caused by Technetium-99m Labeled Pyrene Derivatives
Wunderlich, G.; Reissig, F.; Mamat, C.; Pietzsch, H.-J.; Kotzerke, J.; Steinbach, J.;
Simultaneously with the known γ-emission, 99mTc causes radical-mediated DNA damage due to Auger electrons, which were also emitted. We have synthesized a series of new 99mTc-labeled pyrene derivatives (common DNA intercalators) with varied distances between the pyrene moiety and the radionuclide (Fig. 1). Plasmids (pUC 19) enable the investigation of the unprotected interactions between the labeled pyrene derivatives (3-15MBq) and DNA that results in single-strand breaks (SSB) or double-strand breaks (DSB) separated by gel electrophoresis in 1.4% agarose gel and quantified by fluorescent staining. We used the 99mTc(CO)3-core for pyrene labeling. 99mTc was tightly bound to the plasmid DNA and its damage is mainly dependent on the chain length between the pyrene residue and the Tc-core. It could not be completely prevented by DMSO, a known free radical scavenger. The effectiveness of the DNA-binding 99mTc-labeled pyrene derivatives was demonstrated by comparison to non-DNA-binding [99mTc]NaTcO4, since nearly all DNA damage caused by [99mTc]NaTcO4 was prevented by DMSO. We prepared a 99mTc-complex with an optimal distance between the [99mTc]Tc(CO)3-core and the pyrene residue to position the 99mTc in close proximity to the plasmid DNA to induce direct SSB and DSB. By increasing the distance between the DNA-intercalating moiety and the bonding moiety for 99mTc, we observed decrease of direct DNA damages. This distance dependence has not been reported for 99mTc until now. Clinical relevant Auger electron therapy is hampered by the prerequisite of DNA binding which is hindered by cell and nucleus membranes.
Keywords: 99mTc, Auger, DNA damage, Therapy
  • Poster
    22nd International Symposium on Radiopharmaceutical Sciences (ISRS 2017), Dresden, 14.-19.05.2017, Dresden, Deutschland
  • Open Access LogoJournal of Labelled Compounds and Radiopharmaceuticals 60(2017)S1, S365
    DOI: 10.1002/jlcr.3508

Publ.-Id: 26072 - Permalink


Evaluation of Safety of Light Water Cooled Reactors using CFD
Höhne, T.;
Computational Fluid Dynamics (CFD) is increasingly being used in nuclear reactor safety (NRS) analyses as a tool that enables safety relevant phenomena occurring in the reactor coolant system to be described in more detail.

Numerical investigations on single phase coolant mixing in Pressurized Water Reactors (PWR) have been performed at the FZD for almost a decade. The work is aimed at describing the mixing phenomena relevant for both safety analysis, particularly in steam line break and boron dilution scenarios, and mixing phenomena of interest for economical operation and the structural integrity.

On the other hand slug flow as a multiphase flow regime can occur in the cold legs of pressurized water reactors, for instance after a small break Loss of Coolant Accident (SB-LOCA). Slug flow is potentially hazardous to the structure of the system due to the strong oscillating pressure levels formed behind the liquid slugs. For the experimental investigation of horizontal two phase flows, different non pressurized channels and the TOPFLOW Hot Leg model in a pressure chamber was build and simulated with ANSYS CFX.
Keywords: NRS, LOCA, TOPFLOW, AIAD, CFX, CFD
  • Book chapter
    Arun Nayak: Advances of Computational Fluid Dynamics in Nuclear Reactor Design and Safety Assessment, Amsterdam: Elsevier, 2019, 9780081023372

Publ.-Id: 26071 - Permalink


Stratified and Segregated Flow Modelling - AIAD 2017
Höhne, T.;
Today: Limits in simulating stratified & segregated two phase flow
Algebraic Interfacial Area Density Model (AIAD)
Free Surface Drag
Turbulence Damping
Sub-grid wave turbulence (SWT)
Verification and Validation is going on – more experimental data are required for the validation
Keywords: AIAD, Free Surface Drag, Sub-grid wave turbulence (SWT)
  • Lecture (Conference)
    15th Short Course “Multiphase Flow: Simulation,Experiment and Application”, 14.-17.11.2017, Dresden, Deutschland
  • Contribution to proceedings
    15th Short Course “Multiphase Flow: Simulation,Experiment and Application”, 14.-17.11.2017, Dresden, Deutschland
  • Poster
    15th Short Course “Multiphase Flow: Simulation,Experiment and Application”, 14.-17.11.2017, Dresden, Deutschland

Publ.-Id: 26070 - Permalink


Dipole strength in 80Se below the neutron-separation energy for the nuclear transmutation of 79Se
Makinaga, A.; Massarczyk, R.; Beard, M.; Schwengner, R.; Otsu, H.; Müller, S.; Röder, M.; Schmidt, K.; Wagner, A.;
The gamma-ray strength function ( SF) in 80Se is an important parameter to estimate the neutron-capture cross section of 79Se which is one of the long-lived fission products (LLFPs). Until now, the SF method was applied for 80 Se only above the neutron-separation energy (Sn) and the evaluated 79 Se(n,gamma) cross section has an instability caused by the GSF below Sn . We studied the dipole-strength distribution of 80 Se in a photon-scattering experiment using bremsstrahlung produced by an electron beam of an energy of 11.5 MeV at the linear accelerator ELBE at HZDR. The present photoabsorption cross section of 80 Se was combined with results of (gamma,n) experiments and are compared with predictions usinmg the TALYS code. We also estimated the 79 Se(n,gamma) cross sections and compare them with TALYS predictions and earlier work by other groups.
Keywords: Photon scatterinmg, photoabsorption, cross sections, dipole strength, neutron capture, statistical reaction models.

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Publ.-Id: 26069 - Permalink


Pharmacokinetic/ pharmacodynamic studies of a copper-64 labelled Kv1.3-blocking peptide targeting autoimmune diseases
Kubeil, M.ORC; Bergmann, R.; Zarschler, K.; Stephan, H.; Norton, R. S.
Objectives
The voltage-gated potassium channel Kv1.3 is an attractive therapeutic target to treat autoimmune disorders such as multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus and type-1 diabetes mellitus [1, 2]. This channel is highly expressed in T
effector memory lymphocytes and plays an important role in their activation. A scorpion toxin derived peptide analogue, HsTX1[R14A], blocks Kv1.3 with an affinity in the picomolar range [3].Moreover, this peptide is stabilized by four disulfide bridges, conferring high in vivo stability.
Methods
The peptide was synthesised by SPPS using Fmoc-tBu strategy [3]. The N-terminus of HsTX1[R14A] has been coupled to NOTA (1,4,7-triazacyclononane-triacetic acid) to permit labelling with the positron emitter copper-64. Biodistribution studies and metabolite analysis were carried out in healthy male Wistar rats using Positron Emission Tomography and Radioluminography.
Results
The distribution studies demonstrated a rapid blood clearance after intravenous injection and a fast renal elimination. The highest accumulation was found in the kidney and urine. As a consequence, a long in vivo half-life has been observed. Furthermore, there were no indications of lymphatic cell binding in direct measurements with unfractionated human Tcells.
Conclusion
The promising pharmacological profile of the radiotracer enhances the potential of this peptide to be developed as a therapeutic. Its extraordinary stability and high selectivity for the target channel Kv1.3 make it an attractive candidate for autoimmune disorders.
References
[1] V. Chi, M. W. Pennington, R. S. Norton, E. Tarcha, L. Londono, B. Sims-Fahey, S. K. Upadhyay, J. T. Lakey, S. Iadonato, H. Wulff, C. Beeton, K. G. Chandy, Toxicon 2012, 59, 529-546.
[2] C. Beeton, et al. Proc. Natl. Acad. Sci. U. S. A. 2006, 103, 17414-17419.
[3] M. H. Rashid, R. Huq, M. R. Tanner, S. Chhabra, K. K. Khoo, R. Estrada, V. Dhawan, S. Chauhan, M. W. Pennington, C. Beeton, S. Kuyucak, and R. S. Norton, Sci. Rep. 2014, 4, 1-9.
Keywords: potassium channel, autoimmune disease, PET, peptide
  • Poster
    22nd International Symposium on Radiopharmaceutical Sciences, 14.-19.05.2017, Dresden, Deutschland

Publ.-Id: 26068 - Permalink


Neuartige Calix[4]arene zur Komplexierung von Erdalkalimetallen
Mamat, C.ORC; Bauer, D.; Gott, M.; Pietzsch, H.-J.; Steinbach, J.; Steinberg, J.
Radium-223 und Radium-224 sind klassische alpha-Emitter, die u.a. zu radiotherapeutischen Zwecken Verwendung finden sollen. Radium-223 ist bereits in der klinischen Anwendung, jedoch lediglich als [223Ra]RaCl2, da geeignete Chelatoren für eine stabile Komplexierung dieses Gruppe-2-Metalls fehlen. Komplexbildner die aus (Aza-)Kronenethern und Calixarenen bestehen stellen vielversprechende Kandidaten dar. Von dieses Derivaten wurden Komplexbildungskonstanten bestimmt mit Ba2+ als nichtradioaktives Surrogat aufgrund der ähnlichen chemischen Eigenschaften. Des Weiteren wurden Komplexierungsstudien mit 133Ba durchgeführt.
Keywords: Calixarene, Radium-223, Radiotherapeutika, alpha-Emitter
  • Lecture (Conference)
    Wissenschaftsforum Berlin - GdCh-Jahrestagung, 10.-13.09.2017, Berlin, Deutschland

Publ.-Id: 26067 - Permalink


Dipolar interaction induced band gaps and flat modes in surface-modulated magnonic crystals
Gallardo, R. A.; Schneider, T.; Roldan-Molina, A.; Langer, M.; Fassbender, J.ORC; Lenz, K.; Lindner, J.; Landeros, P.
Theoretical results for the magnetization dynamics of surface-modulated magnonic crystals (SMMCs) are presented. For such systems, the role of the periodic dipolar field induced by the geometrical modulation is addressed by using the plane-wave method. The results unveil that under the increasing of the etched depth, zones with magnetizing and demagnetizing fields act on the system, in such a way that magnonic band gaps are observed in both Damon-Eshbach (DE) and backward volume (BV) geometries. Particularly, in BV configuration, high frequency band gaps and low frequency nearly at modes are obtained. By controlling the geometry of the etched zones, the frequency modes, spatial profiles and forbidden frequency gaps of spin waves (SWs) can be manipulated. To test the validity of the model, the theoretical results of this work are confirmed by micromagnetic simulations, where a good agreement between both methods is achieved. It is demonstrated that the spin-wave dynamics of a surface modulated magnonic crystal contrasts to bi-component magnonic crystals or periodic arrays of wires, for instance, since the SMMCs allow enhancing the magnetizing character in some regions of the film, promoting thus the confinement of the SWs. The theoretical model allows for a detailed understanding of the physics underlying these kind of systems, thereby providing an outlook to potential applications on magnonic devices.
Keywords: magnonic crystals, spin waves, ferromagnetic resonance, magnetization dynamics

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Publ.-Id: 26066 - Permalink


New measurement of the 242Pu(n,γ) cross section at n_TOF-EAR1 for MOX fuels: Preliminary results in the RRR
Lerendegui-Marco, J.; Guerrero, C.; Cortés-Giraldo, M. A.; Quesada, J. M.; Mendoza, E.; Cano-Ott, D.; Eberhardt, K.; Junghans, A.; Aberle, O.; Andrzejewski, J.; Audouin, L.; Bacak, M.; Balibrea, J.; Barbagallo, M.; Bečvář, F.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brown, A.; Caamaño, M.; Calviño, F.; Calviani, M.; Cardella, R.; Casanovas, A.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Colonna, N.; Cortés, G.; Cosentino, L.; Damone, L. A.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Göbel, K.; Gómez-Hornillos, M. B.; García, A. R.; Gawlik, A.; Gilardoni, S.; Glodariu, T.; Gonçalves, I. F.; González, E.; Griesmayer, E.; Gunsing, F.; Harada, H.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Kalamara, A.; Kavrigin, P.; Kimura, A.; Kivel, N.; Kokkoris, M.; Krtička, M.; Kurtulgil, D.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lo Meo, S.; Lonsdale, S. J.; Macina, D.; Marganiec, J.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Maugeri, E. A.; Mazzone, A.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Musumarra, A.; Negret, A.; Nolte, R.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, I.; Praena, J.; Radeck, D.; Rauscher, T.; Reifarth, R.; Rout, P. C.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schumann, D.; Smith, A. G.; Sosnin, N. V.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Warren, S.; Woods, P. J.; Wright, T.; Žugec, P.; The N_Tof Collaboration;
The spent fuel of current nuclear reactors contains fissile plutonium isotopes that can be combined with 238U to make mixed oxide (MOX) fuel. In this way the Pu from spent fuel is used in a new reactor cycle, contributing to the long-term sustainability of nuclear energy. The use of MOX fuels in thermal and fast reactors requires accurate capture and fission cross sections. For the particular case of 242Pu, the previous neutron capture cross section measurements were made in the 70's, providing an uncertainty of about 35% in the keV region. In this context, the Nuclear Energy Agency recommends in its “High Priority Request List” and its report WPEC-26 that the capture cross section of 242Pu should be measured with an accuracy of at least 7–12% in the neutron energy range between 500 eV and 500 keV. This work presents a brief description of the measurement performed at n_TOF-EAR1, the data reduction process and the first ToF capture measurement on this isotope in the last 40 years, providing preliminary individual resonance parameters beyond the current energy limits in the evaluations, as well as a preliminary set of average resonance parameters.
Keywords: 242Pu neutron capture, neutron time-of-flight measurement, CERN nTOF
  • Open Access LogoContribution to proceedings
    International Conference on Nuclear Data for Science and Technology (ND2016), 11.-16.09.16, Bruges, Belgium, 11.-16.09.16, Bruges, Belgium
    European Physical Journal Web of Conferences
    DOI: 10.1051/epjconf/201714611045

Publ.-Id: 26065 - Permalink


Positron Annihilation Studies using a Superconducting Electron LINAC
Wagner, A.; Butterling, M.; Hirschmann, E.; Krause-Rehberg, R.; Liedke, M. O.; Potzger, K.;
The Helmholtz-Center at Dresden-Rossendorf operates several user beamlines for materials research using positron annihilation energy and lifetime spectroscopy. Two beamlines are being operated at a superconducting electron linear accelerator producing hard X-rays from electron-bremsstrahlung and in turn generating positrons from pair production. Both installations employ bunched continuous-wave (CW) electron beams with energies between 15 MeV and 30 MeV. The CW-operation results in significantly reduced pile-up effects in the detectors in comparison to normal conducting accelerators. Electron bunch lengths below 10 ps FWHM allow positron annihilation lifetime spectroscopy measurements with high timing resolutions. The bunch repetition rate is adjustable to 26 MHz / 2n, n=0, 1, 2 ... 16 matching wide spans in positron or positronium lifetimes. The GiPS (Gamma-induced Positron Source) generates energetic electron-positron pairs inside the sample under investigation from hard x-rays impinging onto the sample [2]. Therefore, the source is especially suited for materials which are not qualified for vacuum conditions or because they are imposing hazardous conditions or intrinsic radioactivity. Exemplary defect studies on the skyrmoin-lattice compound MnSi will be presented. MePS (the Monoenergetic Positron Source) utilizes positrons with fixed energies ranging from 500 eV to 16 keV. A magnetic beam transport system guides positrons to the samples under investigation. A dedicated chopper/buncher system is used to maintain a high timing resolution for depth-dependent annihilation lifetime studies in thin films. The signal-to-noise ratio is beyond 104 while lifetime resolutions of around 280 ps FWHM have been obtained. Applications of porosimetry studies in low-k dielectrics and polymer brushes will be presented.
The MePS facility will be extended by an end-station called AIDA2 (Apparatus for in-situ Defect Analysis) where defect studies can be performed in a wide temperature range during thin film growth and ion irradiation. A similar setup named AIDA-1 is already in operation at a 22Na-based mono-energetic continuous positron beam used for Doppler-broadening spectroscopy experiments.
The MePS facility has partly been funded by the Federal Ministry of Education and Research (BMBF) with the grant PosiAnalyse (05K2013). The initial AIDA system was funded by the Impulse- und Networking fund of the Helmholtz-Association (FKZ VH-VI-442 Memriox). The AIDA facility was funded through the Helmholtz Energy Materials Characterization Platform.
Keywords: positron annihilation superconducting LINAC materials science
  • Invited lecture (Conferences)
    International Workshop on Physics with Positrons at Jefferson Lab, 12.-15.09.2017, Newport News, VA, USA
  • Invited lecture (Conferences)
    International Workshop on Positron Studies of Defects 2017 (PSD-17), 03.-08.09.2017, Dresden, Deutschland
  • Open Access LogoAIP Conference Proceedings 1970(2018), 040003
    DOI: 10.1063/1.5040215
  • Lecture (Conference)
    Frühjahrstagung der Deutschen Physikalischen Gesellschaft, 12.-16.03.2018, Berlin, Deutschland

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Publ.-Id: 26064 - Permalink


Liquid metal batteries
Weier, T.; Ashour, R.; Herreman, W.; Horstmann, G.; Kelley, D.; Landgraf, S.; Nimtz, M.; Nore, C.; Personnettaz, P.; Salas, A.; Starace, M.; Stefani, F.; Weber, N.;
Übersicht der Forschungsaktivitäten zu Flüssigmetallbatterien am HZDR
  • Poster
    LIMTECH-Symposium, 19.09.2017, Dresden, Deutschland

Publ.-Id: 26063 - Permalink


Chemical and Electronic Repair Mechanism of Defects in MoS2 Monolayers
Förster, A.; Gemming, S.; Seifert, G.; Tománek, D.;
Using ab initio density functional theory cal- culations, we characterize changes in the elec- tronic structure of MoS2 monolayers introduced by missing or additional adsorbed sulfur atoms. We furthermore identify the chemical and elec- tronic function of substances that have been reported to reduce the adverse effect of sul- fur vacancies in quenching photoluminescence and reducing electronic conductance. We find that thiol-group containing molecules adsorbed at vacancy sites may re-insert missing sulfur atoms. And in the presence of sulfur adatoms, thiols may form disulfides on the MoS2 surface to mitigate the adverse effect of defects.
Keywords: 2D materials, TMD, defects, density-functional, transition metal dichalcogenide, nanoelectronics, catalysis

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Publ.-Id: 26062 - Permalink


High repetition rate, multi-MeV proton source from cryogenic hydrogen jets
Gauthier, M.; Curry, C. B.; Göde, S.; Brack, F.-E.; Kim, J. B.; Macdonald, M. J.; Metzkes, J.; Obst, L.; Rehwald, M.; Rödel, C.; Schlenvoigt, H.-P.; Schumaker, W.; Schramm, U.; Zeil, K.; Glenzer, S. H.;
We report on a high repetition rate proton source produced by high-intensity laser irradiation of a continuously flowing, cryogenic hydrogen jet. The proton energy spectra are recorded at 1Hz for Draco laser powers of 6, 20, 40, and 100 TW. The source delivers ca. 10^13 protons/MeV/sr/min. We find that the average proton number over one minute, at energies sufficiently far from the cut-off energy, is robust to laser-target overlap and nearly constant. This work is therefore a first step towards pulsed laser-driven proton sources for time-resolved radiation damage studies and applications which require quasi-continuous doses at MeV energies.

Publ.-Id: 26061 - Permalink


Nitrogen redistribution in annealed LaFeOxNy thin films investigated by FTIR spectroscopy and EELS mapping
Haye, E.; Pierron, V.; Barrat, S.; Capon, F.; Munnik, F.; Bruyère, S.;
LaFeOxNy thin films have been deposited by magnetron sputtering in Ar/O2/N2 gas mixture at 800°C. Such oxynitride perovskites present an uncommon infrared vibration mode position at 2040cm-1, due to presence of nitrogen, which disappears with heating in air. The evolution of this vibration mode with temperature has been studied and permit to determine an activation energy of thermal degradation of LaFeOxNy. The quantification of nitrogen by Elastic Recoil Detection Analysis (ERDA) before and after heating exhibits the same nitrogen content, indicating a redistribution of nitrogen. Such nitrogen redistribution is observed by Electron Energy Loss Spectroscopy (EELS) mapping, showing migration of nitrogen into grain boundaries, in association with film oxidation.
Keywords: Oxynitride perovskite, Thermal stability, EELS mapping, FTIR

Publ.-Id: 26059 - Permalink


The costimulatory domain in chimeric antigen receptor modified T lymphocytes defines their resistance to immunosuppression by regulatory T cells
Kegler, A.; Koristka, S.; Bergmann, R.; Feldmann, A.; Arndt, C.; Aliperta, R.; Albert, S.; Ziller-Walter, P.; Ehninger, G.; Bornhäuser, M.; Schmitz, M.; Bachmann, M.; Keywords: tumor immunotherapy, CAR design, Treg suppression
  • Lecture (Conference)
    47th Annual Meeting of the German Society for Immunology, 12.09.2017, Erlangen, Germany

Publ.-Id: 26058 - Permalink


Using the novel universal CAR platform technology “UniCAR” to target tumors overexpressing disialoganglioside (GD2)
Mitwasi, N.; Feldmann, A.; Bergmann, R.; Rössig, C.; Bachmann, M.; Keywords: CAR Technology, UniCAR T cells, GD2.
  • Lecture (Conference)
    47th Annual Meeting of the German Society for Immunology, 12.09.2017, Erlangen, Germany

Publ.-Id: 26057 - Permalink


Retargeting of human T lymphocytes to EGFR-expressing cancer cells via nanobody-based target modules using the universal chimeric antigen receptor technology
Albert, S.; Bergmann, R.; Koristka, S.; Feldmann, A.; Arndt, C.; Aliperta, R.; Ehninger, A.; Cartellieri, M.; Ehninger, G.; Steinbach, J.; Bachmann, M.; Keywords: CAR T cell therapy, nanobodies, EGFR-targeting
  • Lecture (Conference)
    47th Annual Meeting of the German Society for Immunology, 12.09.2017, Erlangen, Germany

Publ.-Id: 26056 - Permalink


On the influence of microstructure on fracture behaviour of hot extruded ferritic ODS steels
Das, A.; Viehrig, H. W.; Altstadt, E.; Heintze, C.; Hoffmann, J.;
ODS steels are known to show inferior fracture properties as compared to ferritic martensitic non-ODS steels. Hot extruded 13Cr ODS steel however, showed excellent fracture toughness at a temperature range from room temperature to 400 ˚C. In this work, the factors which resulted in superior and anisotropic fracture behaviour were investigated by comparing different orientations of two hot extruded materials using scanning electron, electron backscatter and transmission electron microscopy. Fracture behaviour of the two materials was compared using unloading compliance fracture toughness tests. Anisotropic fracture toughness was predominantly influenced by grain morphology. Superior fracture toughness in 13Cr ODS-KIT was predominantly influenced by factors such as smaller void inducing particle size and higher sub-micron particle-matrix interfacial strength.
Keywords: ODS-steel, fracture behaviour, fracture toughness, anisotropy, bimodal microstructure, fractography, ductile fracture, void growth and coalescence, critical fracture strain, ductility, void inducing particles

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Publ.-Id: 26055 - Permalink


A pure Java implementation of Generalized Maps
Menzel, P.; Teichmann, J.; van den Boogaart, K. G.;
Each natural object can be represented for digital computations by a decomposition into polyhedral cells.
To handle the topology of such arbitrary cellular partitions specialized data structures are needed.
One example is the concept of Generalized Maps noted for its generality and efficiency.
Nevertheless, only few freely available C/C++ implementations and no native Java implementation of Generalized Maps are known to the authors.
Therefore, we present the open-source Java package de.hzdr.jgm.cgeo.gmap using Generalized Maps as basic concept.
It includes implementations of the theoretical aspects and basic operations as well as high-level approaches for creation and manipulation of cellular objects.
Keywords: Generalized Maps, topology, cellular partitions, Java
  • Software in external data repository
    Publication year 2017
    Programming language: Java
    System requirements: native JDK 1.8.0_92 or higher
    License: GNU General Public License 3.0 (Link to license text)
    Hosted on GitHub: Link to location

Publ.-Id: 26053 - Permalink


Fluid Mechanics of Liquid Metal Batteries
Kelley, D. H.; Weier, T.;
The design and performance of liquid metal batteries, a new technology for grid-scale energy storage, depend on fluid mechanics because the battery electrodes and electrolytes are entirely liquid. Here we review prior and current research on the fluid mechanics of liquid metal batteries, pointing out opportunities for future studies. Because the technology in its present form is just a few years old, only a small number of publications have so far considered liquid metal batteries specifically. We hope to encourage collaboration and conversation by referencing as many of those publications as possible here. Much can also be learned by linking to extensive prior literature considering phenomena observed or expected in liquid metal batteries, including thermal convection, magnetoconvection, Marangoni flow, interface instabilities, the Tayler instability, and electro-vortex flow. We focus on phenomena, materials, length scales, and current densities relevant to the liquid metal battery designs currently being commercialized. We try to point out breakthroughs that could lead to design improvements or make new mechanisms important.
Keywords: liquid metal batteries, Tayler instability, metal pad roll instability, electro-vortex flows

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Publ.-Id: 26052 - Permalink


Complex crustal structures: their 3D grav/mag modelling and 3D printing
Götze, H.-J.; Schmidt, S.; Menzel, P.;
The new techniques are user-friendly because they are highly interactive, ideally real-time and topology conserving and can be used for both flat and spherical models in 3D. These are important requirements for joint inversion for gravity and magnetic modelling of fields and their derivatives, constrained by seismic and structural input from independent data sources. A borehole tool for magnetic and gravity modelling will also be introduced. We are already close to satisfying the demand of treating several geophysical methods in a single model for subsurface evaluation purposes and aim now for fulfilling most of the constraints: consistency of model results and measurements and geological plausibility as well.
For 3D gravmag modelling, polyhedrons built by triangles are used. All elements of the gravity and magnetic tensors can be included. In the modelling interface, after geometry changes the effect on the model is quickly updated because only the changed triangles have to be recalculated. Because of the triangular model structure, our approach can handle complex structures very well and it is flexible (e.g. overhangs of salt domes or plumes). For regional models, the use of spherical geometries and calculations is necessary and available. 3D visualization is performed with a 3D-printer (Ultimaker 2) and gives new insights into even rather complicated Earth subsurface structures.
Inversion can either be run over the whole model, but typically it is used in smaller parts of the model, helping to solve local problems and/or proving/disproving local hypotheses. The basic principles behind this interactive approach are high performance optimized algorithms (CMA-ES: Covariance-matrix-adoption-evolution-strategy). The efficiency of the algorithm is rather high in terms of stable convergence due to topological model validity.
Potential field modelling is always influenced by edge effects. To avoid this, a simple but very robust method has been developed: Derive a density/susceptibility-depth function by taking the mean value of the borders of depth slices through the model. The focus of the presentation is set on two practical study examples: one from the international KTB – Project, Germany´s deep continental borehole, as well as a very complex salt structure in the Northwest German Basin.
Keywords: Potential Field modeling, 3D visualization and printing
  • Poster
    European Geosciences Union General Assembly 2017, 23.-26.04.2017, Wien, Österrreich

Publ.-Id: 26051 - Permalink


Investigation of the Ga Complexation Behaviour of the Siderophore Desferrioxamine B
Jain, R.; Cirina, F.; Kaden, P.; Pollmann, K.;
Gallium (Ga) is a critical element for the electronic industry, however, its long-term supply is not assured. Thus, the recovery of Ga from industrial wastewaters is important. Selective sorption is a recommended technology for the recovery of Ga from industrial wastewaters, however, selective sorbents are elusive. Desferrioxamine B (DFOB), a hydroxomate siderophore that is known to be highly selective towards Fe3+, is tested for its ability to complex Ga. This study demonstrated that DFOB forms 1:1 complex with Ga and the maximum Qe Ga is 124.4 mg of Ga complexed per g of DFOB. Further, the complexation mechanism of Ga3+ and Fe3+ with DFOB is similar, as indicated by NMR, suggesting that the selectivity of DFOB towards Fe3+ will be extended to Ga3+ as well. Thus, DFOB seems to be a suitable candidate for the sorption of Ga from industrial wastewaters.
Keywords: Siderophores, selective, complexation, HPLC, NMR

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Publ.-Id: 26049 - Permalink


Building the third SRF Gun at HZDR
Vennekate, H.; Arnold, A.; Lu, P.; Murcek, P.; Teichert, J.; Xiang, R.;
The multipurpose accelerator ELBE at HZDR which is delivering a large set of secondary beams, is driven by a thermionic DC injector. In order to enhance the beam quality of the machine, the development of superconducting RF injector has been pursued since the early 2000’s. The corresponding ELBE SRF Gun I of 2007 and Gun II of 2014 already delivered beam for the operation of several user beamlines, such as the FEL, positron generation, and THz facility. Currently, the next version – Gun III – and its cryomodule are being assembled, characterized, and prepared for the final commissioning throughout late 2017/early 2018. The new module benefits from the experiences gained with regard to emittance compensation and monitoring of operation variables made with the two predecessors.
Keywords: SRF Gun, Superconductivity, RF, Accelerator, Injector
  • Open Access LogoContribution to proceedings
    International Beam Instrumentation Conference, 20.-24.08.2017, Grand Rapids, USA, 978-3-95450-192-2

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Publ.-Id: 26048 - Permalink


Ground-state configuration of neutron-rich 35Al via Coulomb breakup
Chakraborty, S.; Datta Pramanik, U.; Aumann, T.; Beceiro-Novo, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chartier, M.; Cortina-Gil, D.; de Angelis, G.; Diaz Fernandez, P.; Emling, H.; Ershova, O.; Fraile, L. M.; Geissel, H.; Gonzalez-Diaz, D.; Johansson, H.; Jonson, B.; Kalantar-Nayestanaki, N.; Kröll, T.; Krücken, R.; Langer, C.; Le Bleis, T.; Leifels, Y.; Marganiec, J.; Münzenberg, G.; Najafi, M. A.; Nilsson, T.; Nociforo, C.; Panin, V.; Plag, R.; Rahaman, A.; Reifarth, R.; Ricciardi, M. V.; Rigollet, C.; Rossi, D.; Scheidenberger, C.; Scheit, H.; Simon, H.; Taylor, J. T.; Togano, Y.; Typel, S.; Utsuno, Y.; Wagner, A.; Wamers, F.; Weick, H.; Winfield, J. S.;
The ground-state configuration of 35Al has been studied via Coulomb dissociation (CD) using the LAND-FRS setup (GSI, Darmstadt) at a relativistic energy of ∼403 MeV/nucleon. The measured inclusive differential CD cross section for 35Al, integrated up to 5.0 MeV relative energy between the 34Al core and the neutron using a Pb target, is 78(13) mb. The exclusive measured CD cross section that populates various excited states of 34Al is 29(7) mb. The differential CD cross section of 35Al → 34Al + n has been interpreted in the light of a direct breakup model, and it suggests that the possible ground-state spin and parity of 35Al could be, tentatively, 1/2+ or 3/2+ or 5/2+. The valence neutrons, in the ground state of 35Al, may occupy a combination of either l = 3,0 or l = 1,2 orbitals coupled with the 34Al core in the ground and isomeric state(s), respectively. This hints of a particle-hole configuration of the neutron across the magic shell gaps at N = 20,28 which suggests narrowing the magic shell gap. If the 5/2+ is the ground-state spin-parity of 35Al as suggested in the literature, then the major ground-state configuration of 35Al is a combination of 34Al(g.s.; 4−) ⊗ νp3/2 and 34Al(isomer; 1+) ⊗ νd3/2 states. The result from this experiment has been compared with that from a previous knockout measurement and a calculation using the SDPF-M interaction.
Keywords: Coulomb dissociation electromagnetic strength radioactive beam nuclear astrophysics

Publ.-Id: 26047 - Permalink


The OLCF GPU Hackathon Series: The Story Behind Advancing Scientific Applications with a Sustained Impact
Chandrasekaran, S.ORC; Juckeland, G.ORC; Lin, M.ORC; Otten, M.; Pleiter, D.ORC; Stone, J. E.; Lucio-Vega, J.; Zingale, M.ORC; Foertter, F.ORC
It only took three years to grow from a ``Let's give this a try''-event to a repeatedly copied format with several spin-offs that inspired HPC centers around the world.
Sticking to a few fundamental principles---work on your own code, learn from your mentors just what you need and when you need it, stay flexible in achieving your goal---the week long hackathon format created at Oak Ridge Leadership Computing Facility (OLCF) has been just the spark needed by many groups of scientists to light the fire of a wider GPU adoption in leading-edge as well as university-scale HPC environments.
Most interestingly, the format enabled both ends of the experience spectrum---graduate students vs. post doc fellows---the same kind of progress and chance of success.
Keywords: Parallel Programming; Hackathon; GPU applications; Agile development; Mentoring; Profile guided development
  • Contribution to proceedings
    EduHPC-17: Workshop on Education for High-Performance Computing, 13.11.2017, Denver, CO, USA
    The OLCF GPU Hackathon Series: The Story Behind Advancing Scientific Applications with a Sustained Impact

Publ.-Id: 26046 - Permalink


Invenio Shibboleth-Authenticator
Frust, T.; Schmeisser, N.; Urban, O.;
Module for Invenio that provides authentication via shibboleth.
Related publications
Shibboleth-Authenticator for Invenio (Id 27360) is an alternate identifier of this publication
  • Software in external data repository
    Publication year 2017
    Programming language: Python
    System requirements: Python 2.7, >3.5
    License: GNU General Public License v3.0 (Link to license text)
    Hosted on GitHub: Link to location
  • Software in external data repository
    Publication year 2017
    Programming language: Python
    System requirements: Python 2.7 or Python >3.5
    License: GNU General Public License v3.0 (Link to license text)
    Hosted on PyPI - the Python Package Index: Link to location

Publ.-Id: 26045 - Permalink


Synemin is a novel co-regulator of the radiation-induced DNA damage response in head and neck cancer cells
Deville, S. S.; Förster, S.; Cordes, N.;
Introduction:
Focal adhesion proteins (FAPs) have been shown to essentially contribute to cancer cell therapy resistance. Based on our previous finding that integrins partially control DNA repair processes, we here aim at characterizing the function of FAPs in the DNA damage response. Among others, we identified Synemin, an intermediate filament protein, as novel DNA repair regulator and highly potential novel cancer target in head and neck squamous cell carcinoma (HNSCC).

Methods and materials:
A novel 3D High Throughput esiRNA Screen (3DHTesiRNAs) using (3D)-laminin-rich extracellular matrix (lr-ECM) was established. Screening for residual double strand breaks (DSBs) and clonogenic radiation survival was performed in UTSCC15-pEGFP-53BP1 HNSCC cells upon esiRNA-mediated FAPs knockdown and X-ray exposure (6 Gy). The top 2 targets were validated in a panel of 10 3D lr-ECM HNSCC cell cultures regarding γH2AX/53BP1 foci and clonogenic survival. Immunostaining and 3D chromatin fractionation (CF) of Synemin prior and post irradiation (IR) were performed. Upon Synemin knockdown, DNA repair assay for NHEJ and HR as well as Western Blotting for protein expression and phosphorylation were employed.

Results:
Among a number of interesting novel targets found in our 3DHTesiRNAs, Synemin turned out as novel determinant of HNSCC radiosensitivity. Synemin silencing led to radiosensitization of 3D HNSCC cell cultures. Intriguingly, we showed that Synemin knockdown resulted in a 40% reduction in NHEJ without affecting HR. Concomitantly, phosphorylation of ATM Ser1981, DNA-PKcs Ser2056 and c-Abl Tyr412 were diminished relative to controls. Associated with these observations, we found a dramatic Synemin accumulation in the perinuclear area, which is accompanied by an increased interaction of Synemin with chromatin.

Conclusion:
Our data indicate the interfilament protein Synemin as a new important determinant of DNA repair and radioresistance in HNSCC cells. Ongoing research is focusing on evaluating the molecular mechanism how Synemin participates in NHEJ and chromatin organization.
Keywords: synemin, radiotherapy
  • Poster
    GBS, 17.-20.09.2017, Essen, Deutschland

Publ.-Id: 26044 - Permalink


Identification of beta 8 integrin as novel determinant of pancreatic cancer cell radioresistance
Lee, W.-C.; Jin, S.; Cordes, N.;
Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the five most lethal malignancies in the world and has a 5-year relative overall survival rate of less than 5%. Thus, there is a great need for molecular-targeting strategies. As cell-matrix adhesion is essential for the survival, invasion and therapy resistance, we sought to identify the function of 117 focal adhesion proteins (FAP) in PDAC cell radioresistance. Intriguingly 8 integrin turned out to be one of the most potential novel targets in PDAC.
Material and methods: For FAP detection, we performed a 3D endoribonuclease-prepared siRNA (esiRNA)-based screening (3DHTesiS) in PDAC cell culture (established and primary) grown in laminin-rich extracellular matrix (IrECM). After esiRNA-mediated knockdown and X-ray irradiation (2-6 Gy single dose), clonogenic survival assay and sphere formation were determined. Beta 8 integrin expression level and distribution were detected by using Western blot and immunofluorescence staining. Beta 8 integrin staining was also combined with vesicle trafficking proteins (Caveolin-1, APPL2) and the cis-Golgi matrix protein GM130. Fiji software was used to analyze vesicle distribution after irradiation and Peason’s correlation coefficients were calculated.
Results: We identified a series of novel targets with radiosensitizing potential including beta 8 integrin. Without cytotoxicity, beta 8 integrin knockdown conferred a significant radiosensitizing effect in established patient-derived PDAC cell cultures. Moreover, beta 8 integrin depletion reduced invasion and sphere forming ability. Intriguingly, we found beta 8 integrin located in the perinuclear area colocalized with GM130 but neither in the cell membrane nor colocalized with Caveolin-1 and APPL2. Further, we observed an increased beta 8 integrin expression after irradiation associated with enhanced beta 8 integrin-positive vesicle formation in both cytoplasm and nucleus. This suggests that beta 8 integrin may contribute to intracellular vesicle trafficking under stress conditions.
Summary: We successfully designed a high-throughput radiosensitivity screening method for cell growing in a physiological 3D matrix-based environment. Interestingly, beta 8 integrin has, although not found in the cell membrane to facilitate cell adhesion, a critical role in the radiation response of pancreatic cancer cell. Ongoing work will unravel the underlying mechanisms how beta 8 integrin is controlling cytoplasmic and nuclear survival pathways.
Keywords: integrin, radiotherapy, pdac
  • Poster
    GBS, 17.-20.09.2017, Essen, Deutschland

Publ.-Id: 26043 - Permalink


Flüssigmetallbatterien als Option für elektrische Großspeicher
Nimtz, M.; Weber, N.; Weier, T.;
Übersicht über die Forschungsaktivitäten an Flüssigmetallbatterien am HZDR.
  • Poster
    3. Wissenschaftliches SCI-Treffen "Energiesystemintegration", 11.09.2017, Karlsruhe, Deutschland

Publ.-Id: 26042 - Permalink


Selection of Gallium-binding peptides using Phage Display technology
Schönberger, N.; Matys, S.; Lederer, F.; Pollmann, K.;
Gallium is used essentially in the semiconductor compounds GaAs, GaN or GaP for high-potential future technologies. The resulting rapidly growing demand for gallium shouldn't be exclusively met by the recovery from primary raw material sources.
Biosorptive recycling of gallium from waste waters of the semiconductor industry is a promising and innovative contribution for establishing an economic and clean zero waste technology.
Peptides are excellently suitable ligands for the biosorptive complexation of gallium ions in aqueous solutions due to their variability in their amino acid sequence and their robust properties.
A well-established method for the selection of highly specific peptide ligands in medicine and biotechnology is the phage display technology. Random, short peptide sequences are presented on the surface according to genetically modified bacteriophages. In a biopanning called process, a pool of different bacteriophages is selected against a particular target, thereby enriching specific binding clone variants (figure 1). A very effective method has been established for the selection of different phage display libraries. Gallium ions immobilized on a monolithic ion exchanger are made accessible for biopanning in an FPLC system. This chromatopanning allows the selective enrichment of gallium-binding clone variants under strictly controlled process conditions.
In the present study, we report about the enrichment, identification and characterization of several gallium-binding motifs. Some promising gallium binding bacteriophage clones are chosen for further binding studies. The corresponding peptide sequences can be synthesized and used in subsequent experiments to develop biosorptive materials for selective gallium recovery from industrial waste waters.
Keywords: Phage Surface Display, biopanning, immobilized metal ions, Gallium, metal binding peptides
  • Lecture (Conference)
    6th International Symposium on biosorption and biodegradation/bioremediation, 25.-29.06.2017, Prag, Czech republic

Publ.-Id: 26041 - Permalink


Development of Metal Ion Binding Peptides Using Phage Surface Display Technology.
Schönberger, N.; Matys, S.; Flemming, K.; Lehmann, F.; Lederer, F.; Pollmann, K.;
Phage surface display technology is a useful tool for the identification of biosorptive peptides. In this work it is used for the identification of cobalt, nickel and gallium binding peptides. We present methods for the enrichment of metal ion binding bacteriophage clones from two commercial phage display libraries. One of them presents cyclic heptamer peptides, in which two cysteins flanke the peptide loop (C7C), and a linear dodecapeptide library (D-12).Metal ion selective peptides are suitable to separate as well as concentrate cobalt and nickel from copper black shale leaching products (EcoMetals project) and gallium from industrial waste waters (EcoGaIn project). In contrast to common capture methods of specific binding phage for solid materials the ionic species have to be immobilized prior to the bio-panning procedure. This was realized by chemical complexation of the metal ions using commercial complexing agents on porous matrices. Moreover, an option to harvest non elutable strong binding phage is proposed.
Keywords: Phage Surface Display, biopanning, immobilized metal ions, nickel, gallium, cobalt, metal binding peptides
  • Contribution to proceedings
    22nd International Biohydrometallurgy Symposium, 24.-27.09.2017, Freiberg, Deutschland
    Solid State Phenomena 262, Schweiz: Trans Tech Publications, ISSN: 1662-9779,, 591-595
    DOI: 10.4028/www.scientific.net/SSP.262.591

Publ.-Id: 26040 - Permalink


Measurements of the energy spectrum of secondary neutrons in a proton therapy environment
Dommert, M.; Reginatto, M.; Zboril, M.; Fiedler, F.; Helmbrecht, S.; Enghardt, W.; Lutz, B.;
not available, to be filled in
Keywords: Neutron dosimetry, proton therapy
  • Lecture (Conference)
    Jahrestagung der BIOMEDIZINISCHEN TECHNIK und Dreiländertagung der MEDIZINISCHEN PHYSIK, 10.-13.09.2017, Dresden, Deutschland

Publ.-Id: 26039 - Permalink


Overview on Helmholtz Reactor Safety Research
Kliem, S.ORC; Tromm, W.; Reinecke, E.-A.
The paper gives an overview on the research conducted within the topic "Reactor Safety" of the Helmholtz NUSAFE programme.
  • Lecture (Conference)
    2nd Sino-German Symposium on Fundamentals of Advanced Nuclear Safety Technology, 12.-15.09.2017, Karlsruhe, Deutschland

Publ.-Id: 26038 - Permalink


Hierarchical thermoplastic rippled nanostructures regulate Schwann Cell adhesion, morphology and spatial organization
Masciullo, C.; Dell'Anna, R.; Tonazzini, I.; Böttger, R.; Pepponi, G.; Cecchini, M.;
Periodic ripples are a variety of anisotropic nanostructures that can be realized by ion beam irradiation on a wide class of solid surfaces. Only few authors have investigated these surfaces for tuning the response of biological systems, probably because it is challenging to directly produce them in materials that well sustain long-term cellular cultures. Here, hierarchical rippled nanotopographies with lateral periodicity of ∽300 nm are produced from a gold-irradiated germanium mold in polyethylene terephthalate (PET), a biocompatible polymer approved by the US Food and Drug Administration for clinical applications, by a novel three-steps embossing process. The effects of nano-ripples on Schwann Cells (SCs) are studied in view of their possible use for nerve-repair applications. Data demonstrate that nano-ripples can enhance short-term SC adhesion and proliferation (3-24h from seeding), drive their actin cytoskeleton spatial organization and sustain long-term cell growth. Notably, SCs orient perpendicularly with respect to the nanopattern lines. These results provide information about the possible use of hierarchical nano-rippled elements for nerve-regeneration protocols.
Keywords: hierarchical nanostructures, self-organization, ion Irradiation, cell adhesion, nano-ripples

Publ.-Id: 26037 - Permalink


Ultra-dense planar metallic nanowire arrays with extremely large anisotropic optical and magnetic properties
Jia, Q.; Ou, X.; Langer, M.; Schreiber, B.; Grenzer, J.; Siles, P. F.; Rodriguez, R. D.; Huang, K.; Yuan, Y.; Heidarian, A.; Hübner, R.; You, T.; Yu, W.; Lenz, K.; Lindner, J.; Wang, X.; Facsko, S.;
A nanofabrication method for the production of ultra-dense planar metallic nanowire arrays scalable to wafer-size is presented. The method is based on an efficient template deposition process to grow diverse metallic nanowire arrays with extreme regularity in only two steps. First, III-V semiconductor substrates are irradiated by a low-energy ion beam at an elevated temperature, forming a highly ordered nanogroove pattern by a “reverse epitaxy” process due to self-assembly of surface vacancies. Second, diverse metallic nanowire arrays (Au, Fe, Ni, Co, FeAl alloy) are fabricated on these III-V templates by deposition at a glancing incidence angle. This method allows for the fabrication of metallic nanowire arrays with periodicities down to 45 nm scaled up to wafer-size fabrication. As typical noble and magnetic metals, the Au and Fe nanowire arrays produced here exhibited large anisotropic optical and magnetic properties, respectively. The excitation of localized surface plasmon resonances (LSPRs) of the Au nanowire arrays resulted in a high electric field enhancement, which was used to detect phthalocyanine (CoPc) in surface-enhanced Raman scattering (SERS). Furthermore, the Fe nanowire arrays showed a very high in-plane magnetic anisotropy of approximately 412 mT, which may be the largest in-plane magnetic anisotropy field yet reported that is solely induced via shape anisotropy within the plane of a thin film.
Keywords: self-assembly, metallic nanowire array, reverse epitaxy, magnetic anisotropy, anisotropic dielectric function

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Publ.-Id: 26036 - Permalink


The application of atomic force microscopy in mineral flotation - A critical review
Butt, H.-J.; Xing, Y.; Gui, X.; Cao, Y.; Babel, B.; Rudolph, M.ORC; Weber, S.; Kappl, M.
During the past years, atomic force microscopy (AFM) has matured to be an indispensable surface analytical tool in modern nanomaterials, colloid and interface science, and biological research. A sharp probe mounted near to the end of a cantilever scans along the sample surface providing a high resolution three-dimensional topographic image. On the other hand, the application of AFM used as a force sensor also becomes more and more popular after the invention of the colloidal probe AFM technique. In this review, we highlight the advances in the application of AFM in the field of mineral flotation, such as mineral morphology imaging, mineral-water interface characterization, mineral-reagent interactions, inter-particle interactions, inter-bubble interactions and bubble-particle interactions. Over the coming years, the simultaneous characterization of topography and chemical composition as an imaging tool for AFM and the synchronous measurement of the force and distance involving deformable bubble as a force sensor will become an active area.
Keywords: atomic force microscopy; mineral flotation; surface imaging; inter-particles interaction; bubble-particle interaction

Downloads:

  • Secondary publication expected from 01.06.2019

Publ.-Id: 26035 - Permalink


Therapeutic options to overcome tumor hypoxia in radiation oncology
Troost, E.; Koi, L.; Yaromina, A.; Krause, M.;
Purpose
Expert review summarizing the overcome tumor cell hypoxia by treatment modification in radiation oncology.
Methods
An extensive literature search regarding various means of treatment modification was performed and key papers on those modifications were included in this review article.
Results
Based on the identified key papers the means to overcome hypoxia in radiation oncology were summarized in this review article, e.g., increasing levels of oxygen, combining radiotherapy with agents counteracting hypoxia, or modifying radiation treatment itself.
Conclusions
This review summarizes the results of preclinical and clinical studies counteracting hypoxia and highlights the measures that have found their way into clinical practice.
Keywords: Hypoxia, radiotherapy, oxygenation modification, systemic agents, radiation dose-escalation

Publ.-Id: 26034 - Permalink


Dipole strength distribution in 206Pb for the evaluation of the neutron-capture cross section of 205Pb
Shizuma, T.; Iwamoto, N.; Schwengner, R.; Makinaga, A.; Beyer, R.; Bemmerer, D.; Dietz, M.; Junghans, A.; Kögler, T.; Ludwig, F.; Reinicke, S.; Schulz, S.; Urlaß, S.; Wagner, A.;
The dipole strength distribution of 206Pb was investigated via nuclear resonance fluorescence experiment using bremsstrahlung produced with an electron beam at a kinetic energy of 10.5 MeV at the linear accelerator ELBE. We identified 88 states resonantly excited at energies from 3.7 to 8.2 MeV. The photoabsorption cross sections were extracted from the measured scattering cross sections and the branching ratios. The present (gamma,gamma') data combined with (gamma, n) data from the literature were used as an input to the statistical calculation code CCONE to evaluate the neutron capture cross section of the unstable 205 Pb nucleus.
Keywords: Photon scattering, nuclear resonance fluorescence, bremsstrahlung, photoabsorption cross section, neutron-capture cross section, statistical model

Publ.-Id: 26033 - Permalink


Spin-transfer driven dynamics in hybrid structures
Fowley, C.; Rode, K.; Gallardo, R.; Thiyagarajah, N.; Lau, Y.-C.; Borisov, K.; Betto, D.; Atcheson, G.; Kampert, E.; Wang, Z.; Lindner, J.; Coey, M.; Stamenov, P.; Deac, A. M.;
Since the discovery of giant magnetoresistance, metal spintronics has seen unprecedented advances, from the realisation of ultra-high magnetoresistance ratios to substantial output power from both conventional spin transfer torque oscillators as well as spin-torque vortex oscillators [1]. The recently discovered of the fully compensated ferrimagnetic half-metal, manganese ruthenium gallium (MRG), due to its widely tunable magnetic properties [2], could enable spin torque oscillators which work in the range of hundreds of GHz. Being a ferrimagnet, MRG consists of two magnetic sublattices which are coupled antiferromagnetically to each other. It has been shown that in this material the magnetotransport is dominated by one magnetic sublattice whereas the overall magnetisation is determined by both sublattices [3]. This means that MRG behaves magnetically like an antiferromagnet and electrically like a highly spin polarised ferromagnet, implying that spin-transfer torque would act on one sublattice only, enabling efficient current induced excitations. Due to the different temperature dependences of the sublattice magnetisations, MRG displays a compensation temperature at which the total magnetic moment is zero and the magnetic state is impervious to external magnetic fields [4].
Here we conduct high-field magnetotransport measurements [5] on selected films of MRG with differing Ru concentration and, therefore, different compensation temperatures (Tc). Both the transverse Hall resistivity and longitudinal resistivity are recorded in magnetic fields up to 58T. MRG exhibits a large spontaneous Hall angle of ~2%, coercivity exceeding 1T at room temperature (and several Teslas close to Tc) and has very low net magnetisation of 25kA/m. Despite having a no net magnetic moment at the compensation temperature the magnitude of the Hall signal does not become zero, further indicating both the half-metallic nature of the material and that the magnetotransport is dominated by one sublattice only. An additional feature is observed in the transport data, which resembles a spin-flop transition. By comparison to analytical and mean-field calculations of the sublattice magnetisation directions we can estimate the both the sublattice anisotropy (Hk) and interlayer exchange coupling (Hex). The out-of-phase and in-phase magnetic resonance modes, therefore, lie in the range of 0.3THz and 4THz, respectively. This makes MRG a uniquely tuneable material as a free layer in spin-transfer oscillator applications [6].


References:
[1] Baibich M.N. et al., Physical Review B, 61, 2472 (1988), Ikeda S. et al., Applied Physics Letters, 93 082508 (2008), Tsunegi S. et al., Applied Physics Letters, 109, 252402 (2016)
[2] Kurt H. et al., Physical Review Letters, 112, 027201 (2014)
[3] Borisov K. et al., Applied Physics Letters, 108, 192407 (2016)
[4] Betto D. et al., AIP Advances, 6, 055601 (2016)
[5] Fowley C. et al., Journal of Physics D : Applied Physics, 48, 164006 (2015)
[6] Awari N. et al., Applied Physics Letters, 109, 032403 (2016)
Keywords: magnetism, spin-transfer torque, wireless communication
  • Invited lecture (Conferences)
    Moscow International Symposium on Magnetism, 01.-05.07.2017, Moscow, Russia

Publ.-Id: 26032 - Permalink


Ultrahigh anisotropy Heusler alloys for THz spin-torque oscillators
Deac, A. M.;
Since the discovery of giant magnetoresistance, metal spin electronics has seen unprecedented advances, from the realisation of ultra-high magnetoresistance ratios to substantial output power from spin transfer torque oscillators based on Fe/MgO/Fe-type tunnel junctions which function in the GHz range [1]. The recently discovered class of almost compensated ferrimagnetic manganese gallium pseudo-Heusler alloys, due to their widely tunable magnetic properties [2], could enable the design of spin torque oscillators which work in the range of hundreds of GHz, i.e., covering the THz gap.
To investigate the resonance modes in such compounds, we first conducted high-field magnetotransport measurements [3] on selected films with different composition and, therefore, different compensation temperatures (Tc) and effective anisotropies. In manganese ruthenium gallium (MRG), for instance, both the transverse Hall resistivity and longitudinal resistivity were recorded in magnetic fields up to 58 T, at variable temperature. MRG exhibits a large spontaneous Hall angle of ~2%, coercivity exceeding 1 T at room temperature (and several Teslas close to Tc ) and has very low net magnetisation of 25 kA/m. Despite having no net magnetic moment at Tc, the magnitude of the Hall signal does not become zero, indicating both a half-metallic nature of the material and that the magnetotransport is dominated by one sublattice only. An additional feature is observed in the transport data, which resembles a spin-flop transition. By comparison to analytical and mean-field calculations of the sublattice magnetisation directions, we can estimate both the sublattice anisotropy (Hk ) and interlayer exchange coupling (Hex). Based on these values, the out-of-phase and in-phase magnetic resonance modes are estimated to lie in the range of 0.3 THz and 2 THz, respectively. Furthermore, magnetoresistance ratios as high as 40% at 4.2 K and 12% at room temperature can be obtained when integrating MRG in magnetic tunnel junctions [4].
The out-of-phase resonance mode was also directly measured for ferrimagnetic Mn3-xGa thin films as function of anisotropy and applied magnetic fields (up to 10 T). At low applied fields, we find that the resonance frequency ranges between 200 and 350 GHz for films with different compositions (i.e. anisotropy), providing proof of concept for efficient on-chip emitters of coherent, narrow-band light pulses in the THz gap [5].

References:
[1] Baibich M.N. et al., Physical Review B, 61, 2472 (1988), Ikeda S. et al., Applied Physics Letters, 93 082508 (2008), Tsunegi S. et al., Applied Physics Letters, 109, 252402 (2016)
[2] Kurt H. et al., Physical Review Letters, 112, 027201 (2014)
[3] Fowley C. et al., Journal of Physics D : Applied Physics, 48, 164006 (2015)
[4] Borisov K. et al., Applied Physics Letters, 108, 192407 (2016)
[6] Awari N. et al., Applied Physics Letters, 109, 032403 (2016)
Keywords: magnetism, spin-transfer torque, terahertz communication
  • Invited lecture (Conferences)
    62nd Annual Conference on Magnetism and Magnetic Materials, 06.-10.11.2017, Pittsburgh, USA
  • Invited lecture (Conferences)
    APS March Meeting 2018, 05.03.2018, Los Angeles, USA

Publ.-Id: 26031 - Permalink


Measurement of the lifetime and the proportion of 12C3+ ions in stored relativistic ion beams as a preparation for laser cooling experiments at the CSRe
Wang, H. B.; Wen, W. Q.; Huang, Z. K.; Zhang, D. C.; Hai, B.; Zhu, X. L.; Zhao, D. M.; Yang, J.; Li, J.; Li, X. N.; Mao, L. J.; Mao, R. S.; Wu, J. X.; Yang, J. C.; Yuan, Y. J.; Eidam, L.; Winters, D.; Beck, T.; Kiefer, D.; Rein, B.; Walther, T.; Loeser, M.; Schramm, U.; Siebold, M.; Bussmann, M.; Ma, X.;
We report on an experiment that was conducted in preparation of laser cooling experiments at the heavy-ion storage ring CSRe. The lifetimes of ion beams made up of 12C3+ and 16O4+ ions stored at an energy of 122MeV/u in the CSRe were determined by two independent methods, firstly via a DC current transformer (DCCT) and secondly via a Schottky resonator. Using electron-cooling, the signals of the 12C3+ and 16O4+ ions could be separated and clearly observed in the Schottky spectrum. The obtained individual lifetimes of the 12C3+ and 16O4+ components were 23.6s and 17.8s, respectively. The proportion of 12C3+ ions in the stored ion beam was measured to be more than 70% at the beginning of the injection and increasing as a function of time. In addition to these measurements, the operation and remote control of a pulsed laser system placed directly next to the storage ring was tested in a setup similar to the one envisaged for future laser experiments.
Keywords: Storage ring, Laser cooling, Electron cooling, Schottky pick-up, bunched beam, dynamics

Downloads:

Publ.-Id: 26030 - Permalink


Limits on Supernova- Associated Fe-60/Al-26 Nucleosynthesis Ratios from Accelerator Mass Spectrometry Measurements of Deep-Sea Sediments
Feige, J.; Wallner, A.; Fifield, L. K.; Golser, R.; Merchel, S.; Rugel, G.; Steier, P.; Tims, S. G.; Winkler, S. R.;
We searched for presence of 26Al (t1/2=0.7 Myr) in deep-sea sediments as a signature for extraterrestrial influx. Our data show an exponential dependence of 26Al with the sample age that is fully compatible with radioactive decay of terrigenic 26Al. The same set of samples demonstrated a clear extraterrestrial 60Fe signal between 1.7 and 3.2 Myr ago. Combining our 26Al data with the recently reported 60Fe data [1] gives a lower limit for the local interstellar 60Fe/26Al isotope ratio. Our Limit of 0.24 is higher than the observed average galactic 60Fe/26Al flux ratio of (0.15 + 0.05).It favours the higher ratios deduced from nucleosynthesis models.

Publ.-Id: 26029 - Permalink


Wissenschaftliche Software – Anspruch und Realität im Forschungsprozess
Konrad, U.ORC
Wissenschaftliche Software ist heute unverzichtbares Werkzeug im Forschungsprozess, sie ist Voraussetzung für die Nachvollziehbarkeit der (publizierten) Ergebnisse und in vielen Fällen auch selbst ein Ergebnis, das publiziert, genutzt und langfristig bewahrt werden muss. Publikationen bestehen künftig häufig aus zitierfähigen Texten, Daten und Software und müssen entsprechend konsistent behandelt werden, dies ist eine Herausforderung auch für die Bibliotheken. Daraus ergeben sich eine Reihe von Fragestellungen und Aufgaben für die gute wissenschaftliche Praxis im Umfeld der „Offenen Wissenschaft“ (Open Science). Diese Fragen werden in dem Vortrag diskutiert.
Ausgangspunkt ist die Frage, welche Kategorien wissenschaftlicher Software es gibt und was für Rollen diese im Forschungsprozess spielen. Mit der voranschreitenden Digitalisierung von Forschung und Lehre steigt die Abhängigkeit von Software-Lösungen. Die grundlegenden Prinzipien der „guten wissenschaftliche Praxis“ wie Nachvollziehbarkeit, Reproduzierbarkeit, Transparenz und Qualitätssicherung müssen auch bei der Entwicklung und Nutzung von wissenschaftlicher Software angewandt werden. Allerdings gibt es eine Reihe von Besonderheiten für den Umgang mit Software, da diese im Vergleich zu Veröffentlichungen und Daten einem meist kontinuierlichen Entwicklungsprozess unterliegt und im Kontext spezifischer Entwicklungs- und Laufzeitumgebungen zu betrachten sind.
Darüber hinaus sind die Publikation, Nachnutzbarkeit und Verwertung von Software zentrale Herausforderungen. Die Zitation von Quellcode, die Open Source Software-Entwicklung, die Bereitstellung forschungsnaher Infrastrukturen für Entwicklung und Test sowie die Lizenzen und rechtliche Aspekte der Softwarenachnutzung sind noch nicht umfassend in der wissenschaftlichen Praxis realisiert. Darüber hinaus fehlen auch Anreizsysteme für eine nachhaltige Softwareentwicklung in der Forschung.
Für viele dieser Fragen gibt es Lösungsansätze und „best practice“ Beispiele, auf die eingegangen wird. Seit einiger Zeit gibt es dazu internationale und nationale Initiativen wie u.a. die Software Carpentry (1998, US), das Software Sustainability Institute (2008, GB) und sciforge (2014, D). Des Weiteren unterstützt die Deutsche Forschungsgemeinschaft (DFG) die Entwicklung dieses Gebietes u.a. mit dem Programm ”Research Software Sustainability”.
Keywords: Wissenschaftliche Software, Softwareentwicklung, Publikation, Repositorien, Infrastruktur, Bibliothek, Scientific software, software development, publication, repository, infrastructure
  • Lecture (Conference)
    Internationale Open Access Tage 2017, 11.-13.09.2017, Dresden, Deutschland
    DOI: 10.5281/zenodo.1040289

Publ.-Id: 26025 - Permalink


Two-gap superconductivity in Ag1–x Mo6S8 Chevrel phase
Feig, M.; Bobnar, M.; Veremchuk, I.; Hennig, C.; Burkhardt, U.; Starke, R.; Kundys, B.; Leithe-Jasper, A.; Gumeniuk, R.;
The superconducting properties of Ag1−xMo6S8 [x = 0.08(1)] Chevrel phase [Tc = 7.9(5) K] are studied on a sample compacted by spark plasma sintering. Both lower [Bc1 = 12(1) mT] and the upper [Bc2(0) ~ 7.4(9) T] critical magnetic fields are obtained from magnetization and electrical resistivity measurements for the first time. The analysis of the low-temperature electronic specific heat indicates Ag1−xMo6S8 to be a two band superconductor with the energy gaps delta-1 = 1.6 meV (95 %) and delta-2 = 0.7 meV (5 %). Theoretical DFT calculations reveal a much stronger electron-phonon coupling in the studied Chevrel phase compared to earlier reports.
Keywords: crystal structure, x-ray diffraction methods, superconductivity, specific heat, DFT calculation

Publ.-Id: 26024 - Permalink


The costimulatory domain in CAR T cells determines the resistance to immunosuppression by regulatory T cells
Kegler, A.; Koristka, S.; Bergmann, R.; Feldmann, A.; Arndt, C.; Aliperta, R.; Albert, S.; Ziller-Walter, P.; Ehninger, G.; Bornhäuser, M.; Schmitz, M.; Bachmann, M.;
Chimeric antigen receptor (CAR)-modified T cells are intensively studied for their application in cancer patients and already proved incredible success in clinical trials. However, the choice of the intracellular signaling domain integrated into the CAR architecture can largely influence T cell function and fate, as already shown in vitro and in vivo. Moreover, especially within solid tumors regulatory T cells (Tregs) play an important role in establishing an anti-inflammatory milieu and suppressing effector cells. Consequently, endogenous Tregs might impair CAR-engrafted T cells and thereby affect treatment outcome of cancer patients. Therefore, it is of large interest to investigate the responsiveness of T cells comprising CARs with different intracellular signaling domains on Treg suppression.
To address this question, we isolated CD4+CD25- conventional T cells (Tconv) and genetically modified them to express a universal CAR (UniCAR) construct as part of our previously developed UniCAR platform technology. In contrast to conventional CARs, UniCARs are indirectly linked to their target cells via a separate antigen-specificity providing target module (TM), which allows a flexible application of UniCAR-engrafted T cells against a wide range of tumor-associated antigens. It also enables a modulation of T cell activity between an “on” and “off” status. To compare the influence of different intracellular costimulatory signals, we designed UniCARs containing either a CD3ζ, CD28-CD3ζ or CD137-CD3ζ domain.
By using a lentiviral gene transfer system for genetic modification, transduction rates of more than 80 % were achieved. Upon TM-mediated activation via the UniCAR, Tconvs containing UniCAR28/ζ produced significantly higher amounts of the pro-inflammatory cytokine TNF and the growth-related cytokine IL 2 than UniCAR137/ζ- or UniCARζ-engrafted cells. To investigate the impact of Tregs, Tconvs containing the individual UniCAR constructs were cultured in the presence of expanded, autologous CD4+CD25+CD127lowCD45RA+ Tregs for 96h. On the one hand, Tregs were pre-stimulated with anti-CD3/CD28 beads to mimic polyclonal activation via the endogenous TCR. On the other hand, an antigen-specific stimulation was achieved by engrafting Tregs with UniCARs. In both cases, UniCAR-armed Tconvs showed a distinct responsiveness on Treg suppression in dependence on the intracellular signaling domain. We observed, that in contrast to UniCAR28/ζ-armed Tconvs, UniCAR137/ζ- and UniCARζ-engrafted cells could be substantially repressed by Tregs.
In summary, we could demonstrate that Tconvs containing UniCARs with different intracellular signaling domains display not only a distinct cytokine secretion profile but also a disparate resistance against Treg suppression. These data indicate, that the chosen costimulatory signal has an impact on both the efficacy and the safety of a cancer treatment conducted with genetically modified CAR T cells.
Keywords: tumor immunotherapy, CAR design, Treg suppression
  • Poster
    Third CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference, 06.09.2017, Mainz, Germany

Publ.-Id: 26022 - Permalink


Redirection of human T lymphocytes armed with on/off switchable universal chimeric antigen receptors against various malignant cells
Feldmann, A.; Bergmann, R.; Albert, S.; Metwasi, N.; Arndt, C.; Aliperta, R.; Koristka, S.; Ehninger, A.; Cartellieri, M.; Ehninger, G.; Steinbach, J.; Bachmann, M.;
Recently, chimeric antigen receptor (CAR) expressing T cells have shown tremendous clinic effects in several cancer patients. However once those genetically modified T cells are adoptively transferred in a patient their reactivity cannot be controlled in case of life-threatening side effects or tumor alterations including antigen loss occur. These limitations encouraged us to develop an on/off switchable universal CAR (UniCAR) platform.
As an optimization of conventional CARs, UniCARs do not bind to a cell surface antigen. In contrast their extracellular single-chain fragment variable (scFv) is redirected to the short peptide epitope E5B9 that is physiologically not presented on the surface of living cells. Consequently the UniCAR T cells are inert. Only in the presence of a target module, that exhibits the E5B9 and binds to a tumor surface target, the UniCAR T cells can be cross-linked to tumor cells and thus get activated to kill them. Recently, we have produced a series of monospecific and bispecific target modules against a series of tumor associated antigens including PSCA, PSMA, CD33, CD123, GD2, and EGFR.
Here we demonstrate in vitro as well as in experimental mice that all these target modules are able to efficiently redirect UniCAR T cells against tumor cells in a strictly target-dependent and target-specific manner. Tumor cell killing occurred at pM target module concentrations and the killing efficacy of UniCAR T cells was comparable to conventional CAR T cells. As measured by ELISA and/or flow cytometry-based multiplex assays redirected UniCAR T cells released pro-inflammatory cytokines including for example TNF, IL-2 and IFN-γ but not IL-6. Bispecific tumor targeting mediated superior tumor cell killing effects than the usage of monospecific target modules whereas the amount of released pro-inflammatory cytokines were not increased. Finally, we have proven that redirected UniCAR T cells can kill luciferase-positive tumor cells in immunodeficient mice. In agreement with the UniCAR concept, target modules showed a very short half-life in peripheral blood, could accumulate in established tumors and were released from UniCAR-target module-complexes in a concentration-dependent manner as measured by dynamic PET analysis in mice.
In summary, we established a controllable UniCAR platform for tumor immunotherapy. The reactivity of UniCAR armed T cells can be switched on and off in the presence or absence of target modules and can be regulated in a dose-dependent manner providing an improved safety of the CAR technology. Moreover a variety of different target modules against a series of different tumor targets can be introduced in the UniCAR platform supporting its high flexibility.
Keywords: tumor immotherapy, T cell retargeting, chimeric antigen receptor
  • Poster
    Third CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference, 06.-09.09.2017, Mainz, Deutschland
  • Lecture (Conference)
    Third CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference, 06.-09.09.2017, Mainz, Deutschland

Publ.-Id: 26021 - Permalink


Redirection of human T cells to tumor cells via nanobody-based target modules using the universal chimeric antigen receptor system
Albert, S.; Bergmann, Ralf; Koristka, S.; Feldmann, A.; Arndt, C.; Aliperta, R.; Ehninger, A.; Cartellieri, M.; Ehninger, G.; Steinbach, J.; Bachmann, M.;
In general, adoptive transfer of chimeric antigen receptor (CAR)-expressing T cells has an impressive immunotherapeutic potential. However, due to the time-consuming establishment of new CAR constructs, the risk of life-threatening side effects, and the lack of control mechanisms once infused into patients, we developed a switchable modular CAR platform technology termed UniCAR.
The UniCAR system is composed of two individual components, the universal signal-transducing UniCAR and an exchangeable target module (TM). In contrast to conventional CARs, the single-chain fragment variable (scFv) of the UniCAR binds to a small peptide epitope, which is physiologically not accessible on intact cells. The cross-linkage to tumor cells is mediated via TMs comprising the antigen-specifity and the epitope recognized by the UniCAR. Consequently, UniCAR-engrafted T cells are inert in the absence of redirecting TMs and only switched on in their presence. In addition to the increased safety, the modular structure enables a flexible targeting of different tissue antigens. New TMs can be easily constructed just by fusing the UniCAR epitope to a targeting entity. So far we produced a series of functional scFv-based TMs against different tumor-associated antigens like PSCA, PSMA, GD2 and CD33.
Here we demonstrate that TMs can alternatively contain a nanobody (nb) domain instead of an scFv. Nbs are derived from camelid heavy-chain antibodies, consist of a single variable domain and form the smallest known antigen binding fragments. For redirection of UniCAR T cells to epithelial tumors the frequently overexpressed EGFR is a suitable target antigen. Thus, we generated a nb-based -EGFR TM. As shown by in vitro assays with EGFR+ tumor cell lines, the novel TM efficiently activates UniCAR T cells in a strictly target-specific manner and induces the release of pro-inflammatory cytokines. Furthermore, the data reveal that the -EGFR TM triggers a highly potent tumor lysis at low pM concentrations and redirects UniCAR-engrafted T cells to tumor cells in immunodeficient mice. Using dynamic PET analysis we observed a short half-life of the TM and could confirm its release from UniCAR-TM-complexes. Thereby, it is possible to precisely dose the TM concentration and to rapidly switch the system off in case of adverse side effects. Finally, the -EGFR TM also offers the possibility to image the tumor during therapy. For an increased anti-tumor response we additionally generated a bivalent -EGFR-EGFR TM that shows improved in vitro and in vivo functionality compared to the monovalent construct.
In summary, we established a novel mono- and bivalent nb-based TM for EGFR-specific recruitment of UniCAR T cells which results in an efficient, target-specific and -dependent killing of EGFR+ tumor cells. Thus, we could prove that instead of scFvs also other binding moieties can be used and confirmed the high flexibility of the modular UniCAR platform.
Keywords: CAR T cell therapy, nanobodies, EGFR-targeting
  • Poster
    Third CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference, 06.09.2017, Mainz, Deutschland

Publ.-Id: 26020 - Permalink


Selenium(IV) sorption onto γ-Al2O3: a consistent description of the surface speciation by spectroscopy and thermodynamic modeling
Mayordomo, N.; Foerstendorf, H.; Lützenkirchen, J.; Heim, K.; Weiss, S.; Alonso, U.; Missana, T.; Schmeide, K.ORC; Jordan, N.
The sorption processes of selenium(IV) onto γ-Al2O3 were studied by in situ vibrational spectroscopy, batch sorption studies, zeta potential measurements and Surface Complexation Modeling (SCM). In the pD range from 5 to 9, in situ Attenuated Total Reflection Fourier-transform Infrared (ATR FT-IR) spectroscopy revealed the predominant formation of a single inner-sphere surface species at the alumina surface irrespective of the presence or absence of atmospherically derived carbonate. The adsorption of Se(IV) decreased with increasing pH, and no impact of the ionic strength was observed in the range from 0.01 to 0.1 mol L−1 NaCl. The formation of inner-sphere surface complexes was also suggested from the shift of pHIEP of γ-Al2O3 observed during zeta potential measurements at the highest Se(IV) concentration applied (10−4 mol L−1). Based on these qualitative findings, the acid-base surface properties of γ Al2O3 and the Se(IV) adsorption edges were successfully described using a 1-pK CD-MUSIC model, using one inner-sphere bidentate surface complex. The results of competitive sorption experiments strongly suggested that the surface affinity of Se(IV) towards γ-Al2O3 is higher than that of dissolved inorganic carbon (DIC). Nevertheless, the competing effect might impact the migration of selenium(IV) by reducing the number of available sorption sites on mineral surfaces. Consequently, this should be taken into account in predicting the environmental fate of selenium(IV).
Keywords: Selenium(IV); Sorption; ATR FT-IR spectroscopy; CD-MUSIC; Alumina, Carbonate; Competition

Publ.-Id: 26019 - Permalink


Development of novel target modules for retargeting of UniCAR T cells to GD2 positive tumor cells
Mitwasi, N.; Feldmann, A.; Bergmann, R.; Berndt, N.; Arndt, C.; Koristka, S.; Kegler, A.; Jureczek, J.; Hoffmann, A.; Ehninger, A.; Cartellieri, M.; Albert, S.; Rössig, C.; Ehninger, G.; Pietzsch, J.; Steinbach, J.; Bachmann, M.;
As the expression of a tumor associated antigen (TAA) is commonly not restricted to tumor cells adoptively transferred T cells modified to express a conventional chimeric antigen receptor (CAR) might not only destroy the tumor cells but also attack target-positive healthy tissues. Furthermore, CAR T cells in patients with large tumor bulks will unpredictably proliferate and put the patients at high risk of adverse side effects including cytokine storms and tumor lysis syndrome. To overcome these problems, we previously established a modular CAR technology termed UniCAR: UniCAR T cells can repeatedly be turned on and off via dosing of a target module (TM). TMs are bispecific molecules which cross-link UniCAR T cells with target cells.
After elimination of the respective TM, UniCAR T cells automatically turn off. Here we describe novel TMs against the disialoganglioside GD2 which is overexpressed in neuroectodermal but also many other tumors. In the presence of GD2-specific TMs, we see a highly efficient target-specific and -dependent activation of UniCAR T cells, secretion of pro-inflammatory cytokines, and tumor cell lysis both in vitro and experimental mice. According to PET-imaging anti-GD2 TM enrich at the tumor site and are rapidly eliminated thus fulfilling all prerequisites of a UniCAR TM.
Keywords: immunotherapy, CAR T cells

Publ.-Id: 26018 - Permalink


Qualification tests of optical coatings in space environment
Pelizzo, M. G.; Corso, A. J.; Tessarolo, E.; Martucci, A.; Donazzan, A.; Böttger, R.; Hübner, R.; Napolitani, E.;
Optical components such as mirrors, filters and windows need to be tested and qualified to verify their resistance in space environments. Future space missions, such as ESA JUICE and SOLO, will operate in harsh environments, rich of ions and electrons. Experiments and development of appropriate protocols are needed to develop proper radiation-hard components and to qualify them.
Keywords: Ions, Coatings, Radiation effects, Nonhomogeneous media, Reflectivity, Optical filters, Protons
  • Contribution to proceedings
    2017 IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace), 21.-23.07.2017, Padua, Italy: IEEE, 978-1-5090-4234-0
    DOI: 10.1109/MetroAeroSpace.2017.7999570
  • Lecture (Conference)
    IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace), 21.-23.07.2017, Padua, Italy

Publ.-Id: 26017 - Permalink


Structural and optical studies of Pr implanted ZnO films subjected to a long-time or ultra-fast thermal annealing
Ratajczak, R.; Mieszczynski, C.; Prucnal, S.; Guziewicz, E.; Stachowicz, M.; Snigurenko, D.; Gaca, J.; Böttger, R.; Wojcik, M.; Heller, R.; Skorupa, W.; Borany, J. V.; Turos, A.;
Epitaxial thin ZnO films grown by Atomic Layer Depositionwere implanted with 150 keV Pr ions to a fluence of 1 × 1015 at/cm2. Implanted samples were subjected to two different kinds of annealing: rapid thermal annealing (RTA) and millisecond-range flash lamp annealing (FLA). Structural properties of implanted and annealed ZnO and the optical response were evaluated by the Channeling Rutherford Backscattering Spectrometry (RBS/c), High-resolution X-ray diffraction and Photoluminescence Spectroscopy (PL), respectively. The results shown, that both annealing techniques lead to recrystallization of the ZnO lattice, that was damaged during the ion implantation. Upon RTA performed at 800 °C a return of Zn atoms from interstitial to their regular site positions is accompanied by rejection of primarily substitutional Pr atoms to the interstitial sites. Consequently, it leads to the out-diffusion and precipitation of Pr atoms on the surface. In contrast to RTA, the diffusion of implanted Pr during a millisecond range FLA treatment is completely suppressed. Despite differences in location of Pr inside the ZnO matrix after FLA and RTA, both annealing techniques lead to the optical activation of Pr3+. Interestingly, our RBS/c study for as implanted layers also revealed the anomalous damage peak, called intermediate peak (IP) located between the expected surface and the bulk damage peak. The PL spectra clearly suggest, that the defect which forms the IP, can be assigned to Zn interstitials. The long-time annealing at 800 °C in oxygen atmosphere causes the complete removal of the IP.
Keywords: Zinc oxide Atomic layer deposition Rare-earth Ion implantation Praseodymium Rapid thermal annealing Flash lamp annealing Channeling Rutherford backscattering spectrometry High-resolution X-ray diffraction Photoluminescence

Publ.-Id: 26016 - Permalink


Dosimetric evidence confirms computational model of magnetic field induced dose distortions of therapeutic proton beams
Schellhammer, S. M.ORC; Gantz, S.; Lühr, A.; Oborn, B. M.; Bussmann, M.; Hoffmann, A. L.
Given the sensitivity of proton therapy to anatomical variations, this cancer treatment modality is expected to benefit greatly from integration with magnetic resonance (MR) imaging. One of the obstacles hindering such an integration are strong magnetic field induced dose distortions. These have been predicted in simulation studies, but no experimental validation has been performed so far. Here we show the first measurement of planar distributions of dose deposited by therapeutic proton pencil beams traversing a one-Tesla transversal magnetic field while depositing energy in a tissue-like phantom using film dosimetry. The lateral beam deflection ranges from one millimeter to one centimeter for 80 to 180 MeV beams. Simulated and measured deflection agree within one millimeter for all studied energies. These results proof that the magnetic field induced proton beam deflection is both measurable and accurately predictable. This demonstrates the feasibility of accurate dose calculation as well as measurement within the framework of MR-integrated proton therapy.

Publ.-Id: 26015 - Permalink


Electrical behaviour of carbon nanotubes under low-energy proton irradiation
Abbe, E.; Schüler, T.; Klosz, S.; Starruß, E.; Pilz, W.; Böttger, R.; Kluge, O.; Schmiel, T.; Tajmar, M.;
Several applications for carbon nanotubes (CNT) have been proposed for space applications in the last years. However, their behaviour in the harsh space environment is mostly unknown. Energetic particles such as protons can influence the material degradation in space. This material damage could result in a system failure of space systems. Therefore it is necessary to investigate the performance of new materials under proton irradiation.

Screen and jet printed disordered single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT) and multi-walled carbon nanotubes/resin composites (ME) were exposed to 1 keV, 15 keV and 100 keV protons. The electrical behaviour of the CNT conductor paths was measured during the experiment. After this exposure, the CNTs were analyzed using Raman scattering and a scanning electron microscope (SEM).

Their is a clear evidence that proton radiation can destroy carbon nanotubes and influence their electrical performance.
Keywords: Mulltiwalled carbon nanotubes; Single walled carbon nanotubes; Irradation; Protons; Enviromental behaviour

Publ.-Id: 26014 - Permalink


Beam loading limited high peak current laser wakefield accelerators
Köhler, A.ORC; Couperus, J. P.ORC; Krämer, J. M.; Kurz, T.; Zarini, O.; Pausch, R.; Debus, A.; Garten, M.; Hübl, A.; Bussmann, M.; Schramm, U.; Irman, A.ORC
Laser wakefield accelerators (LWFA) can potentially generate high-peak current electron beams at the order of a few tens of kiloAmperes which are very attractive as drivers for compact secondary radiation sources ranging from THz up togamma-ray or as drivers for beam driven wakefield accelerators (PWFA).
The phenomenon of beam loading affects the amount of trapped charge inside the plasma cavity while influencing the final beam parameters, i.e., transverse emittance and maximum attainable energy and spread.
We experimentally investigate these effects in the self-truncated ionization injection scheme (STII) by loading several hundreds of pC of charge into the wakefield within a monoenergetic bunch. We explore the influence of beam loading on electron energy, energy spread and beam divergence. We show that beam quality is maintained up to an estimated peak-current of 30 kA, which is an order of magnitude higher than can be reached in current state-of-the-art conventional electron accelerators.
  • Poster
    8th International Particle Accelerator Conference, 14.05.2017, Copenhagen, Denmark

Publ.-Id: 26013 - Permalink


Investigation of electron dynamics in a ionization-injection laser-wakefield accelerator via betatron radiation
Koehler, A.ORC; Couperus, J. P.ORC; Zarini, O.; Pausch, R.; Krämer, J. M.; Debus, A.; Irman, A.; Bussmann, M.; Schramm, U.ORC
The features of betatron radiation emitted from accelerated electrons in a laser-wakefield accelerator can help as a diagnostic tool to investigate their dynamics during the acceleration. Here we describe our recent LWFA experiments deploying the ionization induced injection technique carried out with the Draco Ti:Sapphire laser. Equipped with an 2D spectroscopy technique based on single pixel absorption events, we analyze the spectral features of the emitted betatron radiation for a set of different plasma densities. Combined with electron spectra acquired at the same time, the betatron source size for a set of different electron bunches is deduced.
  • Lecture (Conference)
    SPIE Optics + Optoelectronics, 24.04.2017, Prague, Czech Republic

Publ.-Id: 26012 - Permalink


Singularity consideration in the integral equations for contactless inductive flow tomography
Jacobs, R. T.; Wondrak, T.; Stefani, F.;
The Contactless Inductive Flow Tomography is a procedure that enables the reconstruction of the global three-dimensional flow structure of an electrically conducting fluid by measuring the flow induced magnetic flux density outside the melt and by subsequently solving the associated linear inverse problem. The accurate computation of the forward problem which is essential for the inversion represents the focal point of this investigation. The tomography procedure is described by a system of coupled integral equations where the integrals contain a singularity when a source point coincides with a field point. The contribution of a singular point to the value of the surface and volume integrals in the system is considered in detail. A significant improvement of the accuracy is achieved by applying higher order elements and by attributing special attention to the singularities inherent in the integral equations. The treatment of the singularities described in this investigation is similar to the procedure applied in the boundary element method. It represents a novelty in the Contactless Inductive Flow Tomography.
Keywords: Contactless inductive flow tomography, magnetohydrodynamics, integral equations, inverse problems
  • The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 37(2018)4, 1366-1375
    DOI: 10.1108/COMPEL-08-2017-0361

Publ.-Id: 26010 - Permalink


Inclusion of Incidental Radiation Dose to the Cardiac Atria and Ventricles Does Not Improve the Prediction of Radiation Pneumonitis in Advanced-Stage Non-Small Cell Lung Cancer Patients Treated With Intensity Modulated Radiation Therapy
Wijsman, R.; Dankers, F. J. W. M.; Troost, E. G. C.; Hoffmann, A. L.; van der Heijden, E. H. F. M.; de Geus-Oei, L.-F.; Bussink, J.;
Purpose: To evaluate if inclusion of incidental radiation dose to the cardiac atria and ventricles improves the prediction of Grade ≥3 radiation pneumonitis (RP) in advanced stage non-small cell lung cancer (AS-NSCLC) patients treated with intensity-modulated radiation therapy or volumetric-modulated arc therapy.
Material and methods: Using a bootstrap modelling approach, clinical parameters and dose-volume histogram (DVH) parameters of lungs and heart (assessing atria and ventricles separately and combined) were evaluated for RP prediction in 188 AS-NSCLC patients.
Results: After a median follow-up of 18.4 months, 26 patients (13.8%) developed RP. Only the median mean lung dose (MLD) differed between groups (15.3 Gy vs 13.7 Gy for the RP and non-RP group, respectively; p=0.004). The MLD showed the highest Spearman correlation coefficient (Rs) for RP (Rs=0.21; p<0.01). Most Rs of the lung DVH parameters exceeded those of the heart DVH parameters. After bootstrap modelling, the heart DVH parameters were seldom included in the model predicting Grade ≥3 RP. The optimal model for RP consisted of the parameters: MLD and cardiac comorbidity (area under the curve: 0.71).
Conclusion: Incidental dose to the cardiac atria and ventricles did not improve RP risk prediction in our cohort of AS-NSCLC patients.
Keywords: Non-small cell lung cancer; Intensity-modulated radiation therapy; Volumetric-modulated arc therapy; radiation pneumonitis; cardiac exposure.

Publ.-Id: 26009 - Permalink


Use of small animal PET/MRI for internal radiation dose assessment
Kranz, M.;
The thesis is based on three publications investigating newly developed radiotracers in different animal models. The radiation safety and biodistribution has to be proven prior to the application of first-in-man studies. Resultantly, based on the preclinical dosimetry presented herein, a clinical trial was approved by the competent authorities of Germany for (-)-[18F]flubatine, (+)-[18F]flubatine and (S)-(-)-[18F]fluspidine. Although the radiation safety was proven for (R)-(+)-[18F]fluspidine too, so far it is used in preclinical studies only.
  • Doctoral thesis
    Universität Leipzig, 2017
    Mentor: Prof. Brust, Prof. Sattler

Publ.-Id: 26008 - Permalink


Laser-driven proton acceleration from a solid hydrogen ribbon
Kraft, S.;
In the last years, more and more high repetition rate ultrahigh power lasers are build. In order to use the novel capabilities in applications with laser accelerated ion beams, new target types have to be developed. These targets have to fulfil two conditions: they have to stand several hundreds or even thousands of shots and produce as less debris as possible in order to spare the expensive optics. Promising candidates are pure hydrogen targets.
Here we report on experiments with a solid hydrogen ribbon performed at the ELFIE facility in France and compare the results to shots on normal metal and plastic foils.
  • Invited lecture (Conferences)
    Laserlab User Meeting, 27.-29.08.2017, Vilnius, Litauen

Publ.-Id: 26007 - Permalink


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