Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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Only approved publications

30419 Publications
Influence of the magnetic field on the stability of the multiferroic conical spin arrangement of Mn0.80Co0.20WO4
Urcelay-Olabarria, I.; Ressouche, E.; Ivanov, V. Y.; Skumryev, V.; Wang, Z.; Skourski, Y.; Balbashov, A. M.; Popov, Y. F.; Vorob'En, G. P.; Qureshi, N.; Garcia-Munoz, J. L.; Mukhin, A. A.
The evolution of the low temperature antiferromagnetic conical (characterized by two, commensurate and incommensurate propagation vectors), and the high temperature collinear spin arrangements of the 20% Co-doped MnWO4 multiferroic has been studied in the presence of magnetic field up to 60 T by means of macroscopicmagnetic and pyroelectricmeasurements, and by neutron diffraction experiments in fields up to 12 T on a single crystal. The complete magnetoelectric phase diagrams for magnetic fields along distinct magnetic directions with respect to the spin structure have been constructed up to magnetic field values exceeding those necessary to induce a spin-flip transition into the paramagnetic state. The differences in the topology of the diagrams are discussed. The obtained results might be common for other magnetic materials possessing conical antiferromagnetic structures.

Publ.-Id: 28085 - Permalink


Anomalous Hall effect in Weyl semimetal half-Heusler compounds RPtBi (R = Gd and Nd)
Shekhar, C.; Kumar, N.; Grinenko, V.; Singh, S.; Sarkar, R.; Luetkens, H.; Wu, S.-C.; Zhang, Y.; Komarek, A.; Kampert, E.; Skourski, Y.; Wosnitza, J.; Schnelle, W.; Mccollam, A.; Zeitler, U.; Kübler, J.; Yan, B.; Klauss, H.-H.; Parkin, S. P.; Felser, C.
Topological materials ranging from topological insulators to Weyl and Dirac semimetals form one of the most exciting current fields in condensed-matter research. Many half-Heusler compounds, RPtBi (R = rare earth), have been theoretically predicted to be topological semimetals. Among various topological attributes envisaged in RPtBi, topological surface states, chiral anomaly, and planar Hall effect have been observed experimentally. Here, we report an unusual intrinsic anomalous Hall effect (AHE) in the antiferromagnetic Heusler Weyl semimetal compounds GdPtBi and NdPtBi that is observed over a wide temperature range. In particular, GdPtBi exhibits an anomalous Hall conductivity of up to 60 Ω−1·cm−1 and an anomalous Hall angle as large as 23%.Muon spin-resonance (μSR) studies of GdPtBi indicate a sharp antiferromagnetic transition (TN) at 9 K without any noticeable magnetic correlations above TN. Our studies indicate that Weyl points in these half-Heuslers are induced by a magnetic field via exchange splitting of the electronic bands at or near the Fermi energy, which is the source of the chiral anomaly and the AHE.

Publ.-Id: 28084 - Permalink


Low-Temperature Magnetic Hysteresis in Nd(Pr)-Fe-B Nanostructured Alloys with Nd2Fe14B Type Main Phase Composition
Neznakhin, D. S.; Politova, G. A.; Ivanov, L. A.; Volegov, A. S.; Gorbunov, D. I.; Tereshina, I. S.; Kudrevatykh, N. V.
Magnetic hysteresis properties of nanostructured industrially manufactured Nd-Fe-B and Pr-Fe-B alloys on the base of a tetragonal Nd2Fe14B (2-14-1) hard magnetic phase (MQP-B, MQP-B+ and MQP-16-7 brands) have been investigated at 4.2 K in magnetic fields up to 58 T. The chemical composition of the alloys given in the certificates was defined more precisely. The grain sizes of the main 2-14-1 phase were determined. The average grain size is much smaller than a critical single domain diameter. Coercivity, remanence magnetization, saturation magnetization and maximal magnetic energy product were determined at 4.2 K and compared with those obtained at room temperature.

Publ.-Id: 28083 - Permalink


Millisecond Dynamics of the Magnetocaloric Effect in a First- and Second-Order Phase Transition Material
Döntgen, J.; Rudolph, J.; Gottschall, T.; Gutfleisch, O.; Hägele, D.
The millisecond-dynamics of the magnetocaloric effect in Gd and La-Fe-Si-Mn, which exhibit first- and second-order phase-transitions, respectively, are investigated. Direct measurements of the adiabatic temperature change ΔT are obtained from modulation infrared thermometry with field-cycling frequencies exceeding 1 kHz at amplitudes of up to 45 mT. The peak amplitude of ΔT(T) shows a dependence on sample thickness and decreases with increasing modulation frequency for both materials despite a frequency independent susceptibility of Gd. The adiabatic DT depends quadratically on the external field for Gd while La-Fe-Si-Mn shows a peculiar bucket-shaped curve for temperatures below the peak maximum. A comparative study of non-caloric samples shows that dissipative heating by eddy currents or magnetic hysteresis does not explain the observed behavior. The transient ΔT(t) instead suggests a mechanism involving strong temperature gradients at the ferromagnetic–paramagnetic boundaries and underlines the importance of further dynamical studies for a fundamental understanding of the magnetocaloric effect in first-order materials.

Publ.-Id: 28082 - Permalink


Improving landslide susceptibility mapping using morphometric features in the Mawat area, Kurdistan Region, NE Iraq: Comparison of different statistical models
Othman, A. A.; Gloaguen, R.; Andreani, L.ORC; Rahnama, M.
Susceptibility mapping provides information about vulnerable locations and thus helps to potentially decrease infrastructure damage due to mass wasting. During the past decades, expansion of settlements into areas prone to landslides in Iraq has highlighted the importance of accurate landslide susceptibility studies. The main goal of this research is to implement selected morphometric parameters to improve prediction of landslide susceptibility in the Zagros Mountain region. We used the Mawat area, in the Kurdistan Region (NE Iraq) to test the added value of morphometric indicators. Sixteen morphometric factors, mainly derived from a Digital Elevation Model (DEM), extracted using the stereo-ability of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite, as well as geological and environmental predictive factors, were appraised. We evaluated and compared Frequency Ratio (FR), Weight of Evidence (WOE), Logistic Regression (LR) and Probit Regression (PR) approaches in combination with morphometric indices to determine the Landslide Susceptibility (LS). The areas under the curve (AUC) of the Prediction Rate Curve (PRC), Relative landslide density Index (R index), and True Positive Percentage (TPP) for the four models show that all models perform similarly, and the focus should be on careful selection of the predictive factors, which is far more important than the methods used. Results indicate that lithology and slope aspects are the more dominant factors that lead to detect possible occurrence of landslides. Furthermore, this work demonstrates that the hypsometric integral performs better than the commonly used slope curvature as a predictor and thus increases the prediction accuracy of the susceptibility map. We argue that the use of adequate morphometric parameters can increase the efficiency of the LS mapping in other regions of the world.
Keywords: Frequency ratio, Weight of evidence, Logistic regression, Probit regression, Landslide susceptibility (LS), Iraq

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Publ.-Id: 28073 - Permalink


Beyond a phenomenological description of magnetostriction
Reid, A. H.; Shen, X.; Maldonado, P.; Chase, T.; Jal, E.; Granitzka, P. W.; Carva, K.; Li, R. K.; Li, J.; Wu, L.; Vecchione, T.; Liu, T.; Chen, Z.; Higley, D. J.; Hartmann, N.; Coffee, R.; Wu, J.; Dakovski, G. L.; Schlotter, W. F.; Ohldag, H.; Takahashi, Y. K.; Mehta, V.; Hellwig, O.; Fry, A.; Zhu, Y.; Cao, J.; Fullerton, E. E.; Stöhr, J.; Oppeneer, P. M.; Wang, X. J.; Dürr, H. A.
Magnetostriction, the strain induced by a change in magnetization, is a universal effect in magnetic materials. Owing to the difficulty in unraveling its microscopic origin, it has been largely treated phenomenologically. Here, we show how the source of magnetostriction—the underlying magnetoelastic stress—can be separated in the time domain, opening the door for an atomistic understanding. X-ray and electron diffraction are used to separate the sub-picosecond spin and lattice responses of FePt nanoparticles. Following excitation with a 50-fs laser pulse, time-resolved X-ray diffraction demonstrates that magnetic order is lost within the nanoparticles with a time constant of 146 fs. Ultrafast electron diffraction reveals that this demagnetization is followed by an anisotropic, three-dimensional lattice motion. Analysis of the size, speed, and symmetry of the lattice motion, together with ab initio calculations accounting for the stresses due to electrons and phonons, allow us to reveal the magnetoelastic stress generated by demagnetization.

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Publ.-Id: 28072 - Permalink


Measuring the thermal properties of anisotropic materials using beam-offset frequency domain thermoreflectance
Rahman, M.; Shahzadeh, M.; Braeuninger-Weimer, P.; Hofmann, S.; Hellwig, O.; Pisana, S.
Thermoreflectance techniques have become popular to measure the thermal properties of thin films such as thermal conductivity and thermal boundary conductance (TBC). Varying the focused spot sizes of the beams increases the sensitivity to in-plane heat transport, enabling the characterization of thermally anisotropic materials. However, this requires realignment of the optics after each spot size adjustment. Offsetting the probe beam with respect to the pump beam and modulating over a wide range of frequencies (5 kHz to 50 MHz) yield better sensitivity to the thermophysical properties of anisotropic materials without varying the spot sizes. We demonstrate how beam-offset frequency domain thermoreflectance can be used to measure the in- and out-of-plane thermal conductivity as well as the TBC simultaneously from a single data set by working at reduced spot sizes. Lowering the laser spot size allows us to detect signals over a wide range of frequencies and use larger beam offsets, thanks to the increase in the thermoreflectance signal. We measure the anisotropic thermal properties of a range of materials, including single layer Graphene on SiO2, which is of interest for novel electronic devices.
Keywords: Graphene, Thermal conductivity, Optical metrology, Metal oxides, Frequency domain thermoreflectance

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Publ.-Id: 28071 - Permalink


A multicaloric cooling cycle that exploits thermal hysteresis
Gottschall, T.; Gràcia-Condal, A.; Fries, M.; Taubel, A.; Pfeuffer, L.; Manosa, L.; Planes, A.; Skokov, K. P.; Gutfleisch, O.
The giant magnetocaloric effect, in which large thermal changes are induced in a material on the application of a magnetic field, can be used for refrigeration applications, such as the cooling of systems from a small to a relatively large scale. However, commercial uptake is limited. We propose an approach to magnetic cooling that rejects the conventional idea that the hysteresis inherent in magnetostructural phase-change materials must be minimized to maximize the reversible magnetocaloric effect. Instead, we introduce a second stimulus, uniaxial stress, so that we can exploit the hysteresis. This allows us to lock-in the ferromagnetic phase as the magnetizing field is removed, which drastically removes the volume of the magnetic field source and so reduces the amount of expensive Nd–Fe–B permanent magnets needed for a magnetic refrigerator. In addition, the mass ratio between the magnetocaloric material and the permanent magnet can be increased, which allows scaling of the cooling power of a device simply by increasing the refrigerant body. The technical feasibility of this hysteresis-positive approach is demonstrated using Ni–Mn–In Heusler alloys. Our study could lead to an enhanced usage of the giant magnetocaloric effect in commercial applications.

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  • Secondary publication expected from 05.04.2019

Publ.-Id: 28069 - Permalink


High-frequency measurements of thermophysical properties of thin films using a modified broad-band frequency domain thermoreflectance approach
Shahzadeh, M.; Rahman, M.; Hellwig, O.; Pisana, S.
In this work, we present the implementation of a new method to perform high-frequency thermoreflectance measurements on thin films. The so-called differential broad-band frequency domain thermoreflectance method follows broad-band frequency domain thermoreflectance developed previously [Regner et al., Rev. Sci. Instrum. 84 (6), 064901 (2013)], without the use of expensive electro-optic modulators. Two techniques are introduced to recover the thermal phase of interestand to separate it from the unwanted instrumental contributions to the recorded phase. Measuring a differential thermal phase by either varying the spot size or offsetting the pump and probe beams, the thermophysical properties of materials can be extracted. This approach enables the study of nanoscale heat transport where non-equilibrium phenomena are dominating.
Keywords: Thin films, Materials properties, Thermal conductivity, Optical metrology, Frequency domain thermoreflectance

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Publ.-Id: 28068 - Permalink


Single-crystal neutron diffraction study of hexagonal multiferroic YbMnO3 under a magnetic field
Chattopadhyay, S.; Simonet, V.; Skumryev, V.; Mukhin, A. A.; Ivanov, V. Y.; Aroyo, M. I.; Dimitrov, D. Z.; Gospodinov, M.; Ressouche, E.
We report a single-crystal neutron diffraction study of the magnetic structure of the multiferroic compound YbMnO3, a member of the hexagonal manganite family, in zero field and under a magnetic field applied along the c axis. We propose a scenario for the zero-field magnetic ordering and for the field-induced magnetic reorientation of the Mn atom and of the two Yb atoms on distinct crystallographic sites, compatible with the macroscopic measurements, as well as with previous powder neutron diffraction experiments and results from other techniques (optical second-harmonic generation and Mössbauer spectroscopy). Our study should contribute to settling some debated issues regarding the magnetic properties of thismaterial as part of a broader investigation of the entire hexagonal RMnO3 (R = Dy, Ho, Er, Tm, Yb, Lu, Y) family.

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  • Secondary publication expected

Publ.-Id: 28067 - Permalink


Ultrafast laser generated strain in granular and continuous FePt thin films
von Reppert, A.; Willig, L.; Pudell, J.-E.; Rössle, M.; Leitenberger, W.; Herzog, M.; Ganss, F.; Hellwig, O.; Bargheer, M.
We employ ultrafast X-ray diffraction to compare the lattice dynamics of laser-excited continuous and granular FePt films on MgO (100) substrates. Contrary to recent results on free-standing granular films, we observe in both cases a pronounced and long-lasting out-of-plane expansion. We attribute this discrepancy to the in-plane expansion, which is suppressed by symmetry in continuous films. Granular films on substrates are less constrained and already show a reduced out-of-plane contraction. Via the Poisson effect, out-of-plane contractions drive in-plane expansion and vice versa. Consistently, the granular film exhibits a short-lived out-of-plane contraction driven by ultrafast demagnetization which is followed by a reduced and delayed expansion. From the acoustic reflections of the observed strain waves at the film-substrate interface, we extract a 13% reduction of the elastic constants in thin 10 nm FePt films compared to bulk-like samples.
Keywords: Epitaxy, Poisson's ratio, Magnetic devices, Magnetic materials, Stress strain relations, Thin films, Ultrafast X-ray diffraction, Lattice dynamics, Phonons, Elastic modulus

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Publ.-Id: 28066 - Permalink


Ultrafast Self-Induced X-Ray Transparency and Loss of Magnetic Diffraction
Chen, Z.; Higley, D.  J.; Beye, M.; Hantschmann, M.; Mehta, V.; Hellwig, O.; Mitra, A.; Bonetti, S.; Bucher, M.; Carron, S.; Chase, T.; Jal, E.; Kukreja, R.; Liu, T.; Reid, A.  H.; Dakovski, G.  L.; Föhlisch, A.; Schlotter, W.  F.; Dürr, H.  A.; Stöhr, J.
Using ultrafast ≃2.5  fs and ≃25  fs self-amplified spontaneous emission pulses of increasing intensity and a novel experimental scheme, we report the concurrent increase of stimulated emission in the forward direction and loss of out-of-beam diffraction contrast for a Co/Pd multilayer sample. The experimental results are quantitatively accounted for by a statistical description of the pulses in conjunction with the optical Bloch equations. The dependence of the stimulated sample response on the incident intensity, coherence time, and energy jitter of the employed pulses reveals the importance of increased control of x-ray free electron laser radiation.

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Publ.-Id: 28063 - Permalink


Smart Tomographic Sensors for Advanced Industrial Process Control - TOMOCON
Hampel, U.; Wondrak, T.; Bieberle, M.; Lecrivain, G.; Schubert, M.; Eckert, K.; Reinecke, S.
With the recent developments in high-power massive parallel computing, process tomography has gained the required real-time capability of being employed as sensors in advanced control systems. Process tomography techniques are of great value as they provide distributed process parameters for opaque processes.
The European Training Network TOMOCON joins 27 international academic and industry partners working together in the emerging field of industrial process control using smart tomographic sensors to lay the scientific and technological fundamentals of integrating imaging sensors into industrial processes and to demonstrate its functional feasibility on lab and pilot-scale applications. Particular focus is on the training of the doctoral researchers in the fields of process tomography hardware, control systems design, industrial process design, multi-physics modelling, and human-computer interaction.
The teams are engaged in multi-disciplinary research on various tomographic imaging modalities, tomographic image processing as well as advanced multi-physics modelling of processes, sensors and actuators. Proof-of-principle demonstrations of tomography-based processes focus on important industrial processes, such as inline fluid separation, microwave drying of porous materials, continuous steel casting and ultrasound-controlled crystallization.
  • Poster
    ProcessNet-Jahrestagung und 33. DECHEMA-Jahrestagung der Biotechnologen 2018, 10.-15.09.2018, Aachen, Deutschland

Publ.-Id: 28057 - Permalink


Investigation of bioreactors by smart sensor particles
Reinecke, S. F.; Hampel, U.
Advanced monitoring of the spatio-temporal distribution of process parameters in the large-scale vessels of chemical or bioreactors, such as industrial fermenters, biogas digesters and activated sludge basins, offers a high potential for the investigation and further optimization of plants and embedded processes. However, in most industrial scale applications the acquisition of these parameters and their spatial distributions in the large-scale vessels is hampered by the limited access to the process itself, because sensor mounting or cable connections are not feasible or desired. Therefore, state of the art instrumentation of such reactors is commonly limited to few spatial positions where it is doubtfully assumed that the measured parameters are representative for the whole reaction mixture.
Instrumented sensor particles have been developed by Thiele et al. [1] for investigation of hydrodynamic and biochemical processes chemical reactors and bioreactors. 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 and thus flow-following capabilities of the sensor particles [2]. Moreover, controlled floating of the sensor particles is possible to expose them for recovery from the fluid surface. The paper presents results of the sensor system validation and tests in an air-water column reactor, a pilot biogas digester and a waste water treatment plant. Moreover, ongoing developments of smart sensor particles features, i.e. magnetic position detection and inertial position tracking, are presented.
  • Lecture (Conference)
    ProcessNet-Jahrestagung und 33. DECHEMA-Jahrestagung der Biotechnologen 2018, 10.-15.09.2018, Aachen, Deutschland

Publ.-Id: 28056 - Permalink


Inertial position tracking of flow following sensor particles
Reinecke, S. F.; Hampel, U.
In this paper, a concept for inertial position tracking of flow following sensor particles based on data fusion of inertial sensors is presented. The employed data fusion technique is quaternion based and uses an extended Kalman filter algo-rithm. A generalized sensor system kinematics has been developed to test the filter algorithm where two data conditions have been considered. Eventually, first simulation results are compared which shows the performance of the filter re-garding sensor drift and noise.
  • Contribution to proceedings
    Sensoren und Messsysteme 2018 ∙ 26. – 27.06.2018 in Nürnberg, 26.-27.06.2018, Nürnberg, Deutschland
    Beiträge der 19. ITG/GMA-Fachtagung 26. – 27. Juni 2018 in Nürnberg, 978-3-8007-4683-5
  • Lecture (Conference)
    Sensoren und Messsysteme 19. ITG/GMA-Fachtagung 26. – 27. Juni 2018 in Nürnberg, 26.-27.06.2018, Nürnberg, Deutschland

Publ.-Id: 28055 - Permalink


Visible Light Actuated Efficient Exclusion Between Plasmonic Ag/AgCl Micromotors and Passive Beads
Wang, X.; Baraban, L.; R. Misko, V.; Nori, F.; Huang, T.; Cuniberti, G.; Fassbender, J.; Makarov, D.
Insight is provided into the collective behavior of visible‐light photochemically driven plasmonic Ag/AgCl Janus particles surrounded by passive polystyrene (PS) beads. The active diffusion of single Janus particles and their clusters (small: consisting of two or three Janus particles and large: consisting of more than ten Janus particles), and their interaction with passive PS beads, are analyzed experimentally and in simulations. The diffusivity of active Janus particles, and thus the exclusive effect to passive PS beads, can be regulated by the number of single Janus particles in the cluster. On the simulation side, the Langevin equations of motion for self‐propelled Janus particles and diffusing passive PS beads are numerically solved using Molecular‐Dynamics simulations. The complex interactions of both subsystems, including elastic core‐to‐core interactions, short‐range attraction, and effective repulsion due to light‐induced chemical reactions are considered. This complex mixed system not only provides insight to the interactive effect between active visible light‐driven self‐propelled micromotors and passive beads, but also offers promise for implications in light‐controlled propulsion transport and chemical sensing.

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Publ.-Id: 28051 - Permalink


High-Motility Visible Light-Driven Ag/AgCl Janus Micromotors
Wang, X.; Baraban, L.; Nguyen, A.; Ge, J.; R. Misko, V.; Tempere, J.; Nori, F.; Formanek, P.; Huang, T.; Cuniberti, G.; Fassbender, J.; Makarov, D.
Visible light‐driven nano/micromotors are promising candidates for biomedical and environmental applications. This study demonstrates blue light‐driven Ag/AgCl‐based spherical Janus micromotors, which couple plasmonic light absorption with the photochemical decomposition of AgCl. These micromotors reveal high motility in pure water, i.e., mean squared displacements (MSD) reaching 800 µm2 within 8 s, which is 100× higher compared to previous visible light‐driven Janus micromotors and 7× higher than reported ultraviolet (UV) light‐driven AgCl micromotors. In addition to providing design rules to realize efficient Janus micromotors, the complex dynamics revealed by individual and assemblies of Janus motors is investigated experimentally and in simulations. The effect of suppressed rotational diffusion is focused on, compared to UV light‐driven AgCl micromotors, as a reason for this remarkable increase of the MSD. Moreover, this study demonstrates the potential of using visible light‐driven plasmonic Ag/AgCl‐based Janus micromotors in human saliva, phosphate‐buffered saline solution, the most common isotonic buffer that mimics the environment of human body fluids, and Rhodamine B solution, which is a typical polluted dye for demonstrations of photocatalytic environmental remediation. This new knowledge is useful for designing visible light driven nano/micromotors based on the surface plasmon resonance effect and their applications in assays relevant for biomedical and ecological sciences.

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Publ.-Id: 28050 - Permalink


Giant impact of self-photothermal on light-induced ultrafast insulator-to-metal transition in VO₂ nanofilms at terahertz frequency
Zhai, Z.-H.; Chen, S.-C.; Du, L.-H.; Zhong, S.-C.; Huang, W.; Li, Z.-R.; Schneider, H.; Shi, Q.; Zhu, L.-G.
Ultrafast detection and switching of light are key processes in high-speed optoelectronic devices. However, the performances of VO₂-based optoelectronics are strongly degraded by photothermal. The mechanism of the latter is still unclear. Here, by using femtosecond-laser (fs-laser) driven kinetic terahertz wave absorption, we quantitatively separate slow photothermal response and ultrafast photodoping response (e.g. light-induced insulator-to-metal transition) from second- to picosecond-timescales, and discover the competing interplay between them. With self-photothermal (mainly determined by fs-laser pulse repetition rate and pump fluence), the ultrafast transition time was degraded by 190% from 50 ps to 95 ps, the ultrafast transition threshold was decreased to 82% from 11mJ/cm² to 9mJ/cm², while the amplitudes of the two photoresponse are competing. Percolation theory, along with the macroscopic conductivity response, is used to explain the competing interplay. Our findings are relevant for designing and optimizing VO₂-based ultrafast optoelectronic devices.
Keywords: vanadium-dioxide, insulator-to-metal transition, photo-thermal effect

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Publ.-Id: 28042 - Permalink


Detailed characterization of uranyl complexes with small organic ligands on a molecular level: a spectroscopic approach
Brinkmann, H.; Heim, K.; Kaden, P.; Kloditz, R.; Moll, H.; Patzschke, M.
The fundamental aspects of uranyl-spectroscopy (absorption, luminescence, IR), data interpretation and subsequent conclusions to interpret the U(VI)-speciation will be discussed. Furthermore, it will be explained how spectroscopy (NMR and IR) can be used to identify the binding properties of organic molecules, exemplarily explained for a polyhydroxy-carboxylic acid.
Keywords: uranium, spectroscopy, isosaccharinic acid
  • Lecture (others)
    MIND Advanced training course | Geomicrobiology in radioactive waste disposal, 08.-11.10.2018, Mol, Belgien

Publ.-Id: 28040 - Permalink


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

Publ.-Id: 28038 - Permalink


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

Publ.-Id: 28036 - Permalink


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

Publ.-Id: 28035 - Permalink


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

Publ.-Id: 28034 - Permalink


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

Publ.-Id: 28031 - Permalink


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

Publ.-Id: 28030 - Permalink


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

Publ.-Id: 28029 - Permalink


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

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

Publ.-Id: 28026 - Permalink


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

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

Publ.-Id: 28020 - Permalink


“Click to ligand/conjugate” for facile labeling with AlF-18, Ga-68, In-111 or Cu-64
Walther, M.; Wodtke, R.; Bergmann, R.; Zarschler, K.; Sihver, W.; Pietzsch, H.-J.
During the last 10 years an increasing number of ligands were developed and tested for their suitability for AlF-18 labeling. Initially, the well-known macrocyclic ligands NOTA and NODA with low yielding-high temperature reactions were used. In contrast, open chain ligands derived from ethylenediamine provide a fast complex formation at lower temperatures (<40°C). The use of a terminal alkyne linker enables the conjugation to target molecules via copper catalysed azide-alkyne cycloaddition as final step in ligand synthesis. Furthermore, the new triazole containing ligand offers interesting additional applications, besides AlF 18 labeling. In this context, one of the triazole nitrogen atoms could act as an additional soft donor atom to allow the stable fixation of other radiometal ions preferring a six-fold coordination, like Ga-68, In-111 or Cu-64. Examples for the ligand synthesis, radiolabeling experiments, stability studies and initial in vitro and in vivo studies will be presented in this work.
Keywords: CuAAC, [18F]Aluminumfluorid, Cu-64, Ga-68
  • Poster
    TERACHEM2018, 26.-29.09.2018, Bressanone, Italy

Publ.-Id: 28019 - Permalink


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

Publ.-Id: 28018 - Permalink


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

Publ.-Id: 28017 - Permalink


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

Publ.-Id: 28015 - Permalink


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

Publ.-Id: 28014 - Permalink


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

Publ.-Id: 28013 - Permalink


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

Publ.-Id: 28011 - Permalink


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

Publ.-Id: 28010 - Permalink


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

Publ.-Id: 28009 - Permalink


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

Publ.-Id: 28005 - Permalink


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

Publ.-Id: 28004 - Permalink


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

Publ.-Id: 28003 - Permalink


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

Publ.-Id: 28002 - Permalink


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

Publ.-Id: 27996 - Permalink


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

Publ.-Id: 27995 - Permalink


Cognitive correlates of a4b2 nicotinic acetylcholine receptors in mild Alzheimer’s dementia
Sabri, O.; Meyer, P. M.; Graef, S.; Hesse, S.; Wilke, S.; Becker, G.-A.; Rullmann, M.; Patt, M.; Luthardt, J.; Gudrun Wagenknecht, G.; Hoepping, A.; Smits, R.; Franke, A.; Sattler, B.; Tiepolt, S.; Fischer, S.; Deuther-Conrad, W.; Hegerl, U.; Barthel, H.; Schoenknecht, P.; Brust, P.
In early Alzheimer’s dementia, there is a need for PET biomarkers of disease progression with close associations to cognitive dysfunction that may aid to predict further cognitive decline and neurodegeneration. Amyloid biomarkers are not suitable for that purpose. The a4b2 nicotinic acetylcholine receptors (a4b2-nAChRs) are widely abundant in the human brain. As neuromodulators they play an important role in cognitive functions such as attention, learning and memory. Post-mortem studies reported lower expression of a4b2-nAChRs in more advanced Alzheimer’s dementia. However, there is ongoing controversy whether a4b2-nAChRs are reduced in early Alzheimer’s dementia. Therefore, using the recently developed a4b2-nAChR-specific radioligand (-)-18F-flubatine and PET, we aimed to quantify the a4b2-nAChR availability and its relationship to specific cognitive dysfunction in mild Alzheimer’s dementia. Fourteen non-smoking patients with mild Alzheimer’s dementia, drug-naı¨ve for cholinesterase therapy, were compared with 15 non-smoking healthy controls matched for age, sex and education by applying (-)-18F-flubatine PET together with a neuropsychological test battery. The one-tissue compartment model and Logan plot method with arterial input function were used for kinetic analysis to obtain the total distribution volume (VT) as the primary, and the specific binding part of the distribution volume (VS) as the secondary quantitative outcome measure of a4b2-nAChR availability. VS was determined by using a pseudo-reference region. Correlations between VT within relevant brain regions and Z-scores of five cognitive functions (episodic memory, executive function/working memory, attention, language, visuospatial function) were calculated. VT (and VS) were applied for between-group comparisons. Volume of interest and statistical parametric mapping analyses were carried out.
Analyses revealed that in patients with mild Alzheimer’s dementia compared to healthy controls, there was significantly lower VT, especially within the hippocampus, fronto-temporal cortices, and basal forebrain, which was similar to comparisons of VS. VT decline in Alzheimer’s dementia was associated with distinct domains of impaired cognitive functioning, especially episodic memory and executive function/working memory. Using (-)-18F-flubatine PET in patients with mild Alzheimer’s dementia, we show for the first time a cholinergic a4b2-nAChR deficiency mainly present within the basal forebrain-cortical and septohippocampal cholinergic projections and a relationship between lower a4b2-nAChR availability and impairment of distinct cognitive domains, notably episodic memory and executive function/working memory. This shows the potential of (-)-18F-flubatine as PET biomarker of cholinergic a4b2-nAChR dysfunction and specific cognitive decline. Thus, if validated by longitudinal PET studies, (-)-18F-flubatine might become a PET biomarker of progression of neurodegeneration in Alzheimer’s dementia.
Keywords: (-)-18F-flubatine; PET; cognitive dysfunction; a4b2-nAChRs; Alzheimer’s dementia Abbreviations: a4b2-nAChR = a4b2 nicotinic acetylcholine receptor; GMD = grey-matter density; PVEC = partial volume effect correction; VND = non-displaceable distribution volume; VS = specific binding part of the distribution volume; VT = distribution volume

Publ.-Id: 27993 - Permalink


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

Publ.-Id: 27992 - Permalink


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

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Publ.-Id: 27990 - Permalink


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

Publ.-Id: 27987 - Permalink


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

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

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

Publ.-Id: 27986 - Permalink


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

Publ.-Id: 27985 - Permalink


Is It Here/There Yet? - Real Life Experiences of Generating/Evaluating Extreme Data Sets Around the World
Juckeland, G.ORC; Huebl, A.ORC; Bussmann, M.ORC
Large scale simulations easily produce vast amounts of data that cannot always be evaluated in-situ. At that point parallel file systems come into play, but their per node performance is essentially limited to about the speed of a USB 2.0 thumb drive (e.g. the Spider file system at OLCF provides over 1 TB/s write bandwidth, but with 18000+ nodes of Titan writing simultaneously, this number is reduced to about 50 MB/s per node). Making the most out of such a limited resource requires I/O libraries that actually scale. In addition such libraries also offer on the fly data transformations (e.g. compression) to better utilize the raw I/O bandwidth, albeit, opening a new can of worms by trading compression throughput with compression ratios for performance. We will present a detailed study of I/O performance and various compression techniques at OLCF and compare them against smaller local I/O installations, demonstrating the highest achieved I/O performance for real world applications at OLCF. Furthermore, we demonstrate that the best performing I/O setup can be determined prior to starting the job based on hardware characteristics.
Now that you have your data on disk the clock starts ticking and you are fighting against the deadline until your data will be purged, since most centers only offer the high performing storage spaces on a temporary basis. Extracting all valuable information out of a petabyte sized data set requires parallel processing as well and induces wait times until the resources are available and quite naturally a lot of trial-and-error for the evaluation. The time constraint for keeping the temporary data becomes even more troublesome when trying to compare multiple large simulations that naturally have a delay of multiple days until they are scheduled and write their results. And ideally analysis could embrace the data of multiple simulations of a quarterly accounted, yet year-long computing campaign. Another challenge for actually conducting scientific discoveries comes when utilizing multiple compute sites. This seems to be rather usual for research groups as they will use all the compute clock cycles they
can get wherever that may be. For comparative studies the data sets now need to be available at the same time for analysis, e.g. via archiving solutions or transfer to one location. The achievable transfer bandwidth between data centers is in our experience still much lower than expected. The talk will also present on the experiences of evaluating petabyte sized data sets in such a diverse environment.
  • Lecture (Conference)
    Extreme Data Workshop 2018, 18.-19.09.2018, Jülich, Deutschland

Publ.-Id: 27984 - Permalink


Advanced proxies for provenance, erosion and transport mechanisms of modern stream sediments – An application of SEM-based quantitative mineralogical analysis
Rütters, S.; Tolosana-Delgado, R.; Gutzmer, J.
In order to analyse stream sediments for provenance with respect to erosion and transport mechanisms, several methods are established (e.g. bulk sediment geochemistry, mineralogy (provided by XRD) and indicator mineral analysis). In this study, we make use of automated mineralogy by Mineral Liberation Analyser (MLA) as a potentially tool to advance sediment provenance studies.
The MLA combines backscattered electron (BSE) imaging with energy dispersive X‐ray spectrometry (EDS) generating compositional data each sediment particles of the sample. The provided data include particle as well as mineral grain parameters (i.e. size and shape) as well as the mineralogical composition and properties (e.g. elemental composition, density) of each particle (including individual constituting mineral grains). The aim is to join the provided parameters in a holistic model including statistical automatisms. In order to ensure a valid combination of the heterogenic and voluminous set of data provided by MLA, robust statistical analyses are needed. These statistical analyses unveil trends and dependencies in suites of related samples. Furthermore, in this study bulk geochemistry and XRD measurements are integrated to guaranty the quality of the introduced method and subsequently to critically assess the benefit of the measurement.
The study area is located in the Vogtland region of the Free State of Saxony (Germany). The variscan bedrocks comprise plutonic (i.e. different types of granite) and metamorphic units (mica schists, phyllites and quartzites), which are very well studied. Especially since, the Vogtland and the neighbouring Erzgebirge are well known for the occurrence of granite‐related mineral systems, represented as polymetallic deposits (skarn‐, vein‐, stockwork‐, and greisen‐type). In addition, this area is menial populated, suggesting a restricted anthropogenic contaminations of the stream sediment.
First results of this study, give rise for a clear improvement in the detection of lithological changes of the source rock composition and transport features of the unconsolidated sediments. This can be easily identified, based on the modal mineralogy, geochemical changes and grain‐parameter patterns. In addition, mixing of the material can be calculated with respect lithological changes along the river path. Another issue, is to detect the anthropogenic contamination of the sampled material and to balance the impact to the chemical composition.
  • Open Access LogoContribution to proceedings
    WGSG Dublin IV, 27.-29.06.2018, Dublin, Ireland

Publ.-Id: 27979 - Permalink


Formation of n- and p-type regions in individual Si/SiO2 core/shell nanowires by ion beam doping
Berencén, Y.ORC; Prucnal, S.; Möller, W.; Hübner, R.; Rebohle, L.; Schönherr, T.; Bilal Khan, M.; Wang, M.; Glaser, M.; Georgiev, Y. M.; Erbe, A.; Lugstein, A.; Helm, M.; Zhou, S.ORC
A method for cross-sectional doping of individual Si/SiO2 core/shell nanowires (NWs) is presented. P and B atoms are laterally implanted at different depths in the Si core. The healing of the implantation-related damage together with the electrical activation of the dopants takes place via solid phase epitaxy driven by millisecond-range flash lamp annealing. Electrical measurements through a bevel formed along the NW enabled us to demonstrate the concurrent formation of n- and p-type regions in individual Si/SiO2 core/shell NWs. These results might pave the way for ion beam doping of nanostructured semiconductors produced by using either top-down or bottom-up approaches.
Keywords: nanowires, ion beam doping, flash lamp annealing

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  • Secondary publication expected from 25.09.2019

Publ.-Id: 27975 - Permalink


First time in vivo assessment of sigma-1 receptor binding (Sig-1R) in the brain of unmedicated acute major depressive disorder (MDD) using the novel Sig-1R-specific radioligand (-)-[F-18]Fluspidine and PET
Meyer, P. M.; Strauß, M.; Becker, G. A.; Hesse, S.; Bednasch, K.; Ettrich, B.; Zientek, F.; Rullmann, M.; Luthardt, J.; Fischer, S.; Patt, M.; Wünsch, B.; Brust, P.; Sabri, O.
Ziel/Aim:
The Sig-1R is a chaperone protein localized at the endoplasmatic reticulum (ER) that can translocate under ER stress, a mechanism which is critically involved in the pathophysiology of MDD. In order to investigate the pathophysiology of Sig-1R regulation in MDD, for the first time we quantitatively assessed Sig-1R binding in the brain of unmedicated, acute MDD and compared it with healthy controls (HC) using the novel radioligand (-)-[F-18]Fluspidine and PET.
Methodik/Methods:
Unmedicated, moderate to severe, acute MDD (n=12; 33±13ys; 6 males: HAMD: 19.0±4.3; MDD+ with family histora [n=6] and MDD- without family history of depression [n=6]), were investigated using(-)-[F-18]Fluspidine PET (300 MBq, ECAT Exact HR+) and compared with age-/sex-matched healthy controls (HC; n=9; 37±16ys [n.s.]; 4 males [n.s]). Distribution volume parameters (VT) were determined using full pharmacokinetic modelling (2TCM, metabolite correction). Regional VOI-analyses were carried out.
Ergebnisse/Results:
Compared with HC, in MDD, VT was significantly higher within the ncl. caudatus, ncl. accumbens, fronto-temporo-parieto-occipital and cingulate cortices, insula, amygdala, thalamus and midbrain/raphe (+15 to +24%, P<0.05). Compared with MDD-, in MDD+, VT was higher in the fronto -temporo and cingulate cortices, insula, hippocampus, putamen, thalamus (P<0.05). There was an inverted U-relationship between the severity of MDD (HAMD) and VT in the fronto-temporo-parietal and posterior cingulate cortices and thalamus (P<0.05).
Schlussfolgerungen/Conclusions:
Using (-)-[F-18]Fluspidine PET, we demonstrate for the first time higher Sig-1R binding in meso-striato-cortico-limbic and paralimbic brain regions of unmedicated, acute MDD. Higher Sig-1R binding in MDD+, compared with MDD-, may express different subtypes of depression. Increased Sig-1Rs in acute MDD and the inverted U-relationship between severity and Sig-1R may reflect neuroadaptive uptregulation of Sig-1R counteracting ER stress that is exhausted in the severest stages of MDD leading to apoptosis.
  • Lecture (Conference)
    56. Jahrestagung der DGN, 18.-21.04.2018, Bremen, Deutschland
  • Abstract in refereed journal
    Nuklearmedizin 56(2018), V65

Publ.-Id: 27974 - Permalink


Ion acceleration with on-shot monitored ultra-high contrast using the DRACO Petawatt laser facility
Ziegler, T.ORC; Bernert, C.; Bock, S.; Brack, F.-E.; Bussmann, M.ORC; Garten, M.ORC; Kraft, S.ORC; Kroll, F.ORC; Metzkes-Ng, J.ORC; Obst, L.ORC; Oksenhendler, T.; Rehwald, M.ORC; Schlenvoigt, H.-P.ORC; Schramm, U.ORC; Zeil, K.
Laser-driven ion acceleration promises to provide a compact solution for demanding applications like particle therapy, proton radiography or inertial confinement research. Controlling the beam parameters to achieve these goals is currently pushing the frontier of laser driven particle accelerators.
We present an overview of recent achievements at the high power ultra-short pulse laser source DRACO at the HZDR in Dresden (Germany). The laser system was recently upgraded by new front end components and an additional Petawatt (PW) amplifier stage, finally providing high contrast pulses of 30J within 30fs at 1 Hz pulse repetition rate.
The performance of the plasma acceleration is strongly dependent on the complex pre-plasma formation process at the target front surface which is determined by the temporal intensity contrast. Plasma mirror setups have proven to be a valuable tool to significantly improve the temporal contrast by reducing pre-pulse intensity and steepening the rising edge of the main laser pulse. Re-collimating single plasma mirror devices have therefore been implemented into the Draco laser beam lines, enabling investigation of laser proton acceleration and proton energy scaling within the TNSA regime using ultra-thin foil targets.
The results of the simultaneously measured proton emission energies in laser forward direction, laser backward direction and the temporal contrast, measured on a single-shot base by means of self-referenced spectral interferometry with extended time excursion (SRSI-ETE) at unprecedented dynamic and temporal range, will be presented.
  • Poster
    45th Conference on Plasma Physics, 02.-06.07.2018, Prague, Czech Republic

Publ.-Id: 27973 - Permalink


All-optical shaping of laser-driven proton beam profiles
Ziegler, T.ORC; Obst-Huebl, L.ORC; Brack, F.-E.; Branco, J.; Bussmann, M.ORC; Cowan, T. E.ORC; Curry, C. B.ORC; Fiuza, F.ORC; Garten, M.ORC; Gauthier, M.ORC; Göde, S.; Glenzer, S. H.; Huebl, A.ORC; Irman, A.; Kim, J. B.; Kluge, T.ORC; Kraft, S.ORC; Kroll, F.ORC; Metzkes-Ng, J.ORC; Pausch, R.ORC; Prencipe, I.; Rehwald, M.ORC; Rödel, C.; Schlenvoigt, H.-P.ORC; Schramm, U.ORC; Zeil, K.
Extreme field gradients intrinsic to relativistic laser plasma interactions enable compact MeV proton accelerators with unique bunch characteristics, yet complicate direct proton beam control. Only complex micro-engineering of the plasma accelerator itself and limited adoption of conventional beam optics, so far provided access to global beam parameters as direction and divergence. Here we present a novel, counter-intuitive, yet readily applicable all-optical approach to imprint detailed spatial information from the driving laser pulse to the proton bunch. In a series of experiments, the spatial profile of the energetic proton bunch was found to exhibit identical features as the fraction of the laser pulse passing around a target of limited size. The formation of quasi-static electric fields in the beam path by ionization of residual gas in the experimental chamber results in asynchronous information transfer between the laser pulse and the naturally delayed proton bunch. Essentially acting as a programmable memory, these fields provide access to a new level of proton beam manipulation.
  • Poster
    8th Conference of the International Committee on Ultrahigh Intensity Lasers, 09.-14.09.2018, Lindau, Germany

Publ.-Id: 27972 - Permalink


A fine future - Flotation in times of circular economy and energy transition
Rudolph, M.ORC
The invention of flotation about 140 years ago was one of the great achievements of modern processing technology. For many metallic/mineral raw materials, processing without a flotation stage would be unthinkable. This article presents the especially important topics in the field of basic research and technological development of flotation in times of the circular economy and energy transition.
Keywords: Flotation, Circular Economy, Energiewende
  • Open Access LogoAT Mineral Processing 59(2018), 56-64

Publ.-Id: 27971 - Permalink


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

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Publ.-Id: 27969 - Permalink


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

Publ.-Id: 27968 - Permalink


Scalable Multi-Platform PIC Simulations as an Open Science Service
Huebl, A.ORC; Pausch, R.; Widera, R.; Garten, M.; Debus, A.; Goethel, I.; Matthes, A.; Worpitz, B.; Starke, S.; Kelling, J.; Kossagk, S.; Bastrakov, S.; Kluge, T.; Juckeland, G.; Schramm, U.; Cowan, T. E.; Bussmann, M.
PIConGPU is a fully open, community-driven, 3D and 2D3V particle-in-cell code for the age of heterogeneous, many-core driven supercomputing. Developed in a single source C++ code base, PIConGPU supports both "traditional" CPU architectures as well as modern and highly parallel architectures such as OpenPOWER, Xeon Phi, and Nvidia GPUs.

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

PIConGPU is further complemented by modern methods for photon generation, transport, as well as X-ray interaction. This simulation framework aims to provide documented, installable, and re-usable software components for the community, well-suited for open data (openPMD) and open science workflows without restrictions. Latest developments include a python-centric, extensive framework for specific experiments, which provides all of the above in an intuitive, non-expert user interface.
Keywords: PIConGPU, Scalability, performance-portability, Open Source, Open Science, FOSS, Open Data, In Situ processing, SaaS, GPU, Big Data
  • Lecture (Conference)
    18th Advanced Accelerator Concepts Workshop (AAC 2018), 12.-17.08.2018, Breckenridge (CO), United States of America
    DOI: 10.5281/zenodo.1345080
  • Poster
    18th Advanced Accelerator Concepts Workshop (AAC 2018), 12.-17.08.2018, Breckenridge (CO), United States of America

Publ.-Id: 27965 - Permalink


Data Analysis and Simulations in Exascale Computing: Quō vādis?
Huebl, A.ORC; Ehrig, S.; Bussmann, M.
We are less than three years apart from the first, double precision Exa-Flop/s supercomputers. Already today, our scientific software stacks are facing the challenge to run efficiently on a potpourri of architectures. But the real troubles might await us at the choke points of extreme data rates, where traditional workflows of data acquisition, filtering, processing and subsequent long-term storage might not be able to be sustained anymore.

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

This talk will present our vision for the next years of data-driven scientific computing. Based on our experience with single-source, performance-portable C++ HPC libraries, we will present zero-overhead C++ abstractions that spare code-duplication. Together with light-weight code coupling, possible directions for analyzing resulting data rates are discussed on examples from laser-driven particle accelerator research. With such meta-programming approaches, an underestimated risk lies in cutbacks for both development workflows and user interactivity at runtime, which we want to openly change with interactive Cling-assisted execution in modern environments such as Jupyter, for which we recently enabled CUDA C++ capabilities.
Keywords: Exascale, C++, Scientific Computing, Open Data, Interactivity, GPU, Manycore, Open Source
  • Invited lecture (Conferences)
    ROOT User's Workshop, 10.-13.09.2018, Sarajevo, Bosnien und Herzegowina
    DOI: 10.5281/zenodo.1412537

Publ.-Id: 27964 - Permalink


openPMD - An Open Standard for Particle-Mesh Data Files
Huebl, A.ORC; Lehe, R.ORC; Vay, J.-L.ORC; Grote, D. P.; Sbalzarini, I. F.ORC; Kuschel, S.; Sagan, D.ORC; Pérez, F.; Koller, F.ORC; Bussmann, M.ORC
Data fuels and substantiates scientific discoveries. Advanced particle accelerator research is no different and has an inherent need for high-rate, high-resolution data. But in recent years, generating and handling the sheer amount data that is driving our discoveries became challenging. Just to name a few: scalable output from 3D simulations breaks down for modern supercomputers, high-rate Mpixel cameras generate GByte/s for laser control and comparing even just simulations to each other is a significant, manual, error-prone process.

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

openPMD tries to follow best-practices towards an open-science workflow. While the meta standard is developed in an open, reviewable, versioned technical document, a large collection of tools and bindings develop around it. We will take a look at the community that fuels openPMD, the open-source projects evolving around it, adopters in the domain of astro-physics, photon-science and classical accelerator physics and the latest updates arriving in openPMD 2.0.0 .
Keywords: openPMD, open data, open science
  • Lecture (Conference)
    SIMEX Developer Workshop, 16.04.2018, Hamburg, Deutschland
    DOI: 10.5281/zenodo.1219733
  • Lecture (Conference)
    EUCALL (SIMEX) Annual Meeting, 30.05.-01.06.2018, Prague, Czech Republic
  • Lecture (Conference)
    18th Advanced Accelerator Concepts Workshop, 12.-17.08.2018, Breckenridge (CO), United States of America
    DOI: 10.5281/zenodo.1345077

Publ.-Id: 27962 - Permalink


HPC as a Tool for Better Science
Huebl, A.ORC; Juckeland, G.ORC
While High Performance Computing (HPC) has been around for decades, it has been largely seen as a small niche for very limited scientific challenges. The cloud computing revolution had the wonderful side effect that everybody can now easily accept that certain tasks are transparently performed elsewhere. Web-based user interfaces enable an application interaction regardless of the actual location of the computation. As such more and more HPC centers offer web-portals to access their systems and applications also offer a web-based front-end, so that the obscure green font on black screen magic of a typical SSH session is hidden from the end user. This enables both new groups to use HPC systems but also provides power users a more error proof and efficient way of using installed applications. This talk showcases how this application as a service mode has changed the computing landscape in a multi-disciplinary research laboratory both from a users and an HPC operators perspective.
Keywords: HPC, Open Science, SaaS, PIConGPU
  • Invited lecture (Conferences)
    SIAM Conference on Parallel Processing for Scientific Computing, 07.03.2018, Tokio, Japan

Publ.-Id: 27961 - Permalink


Modeling Laser-Plasma Interaction with PIConGPU
Huebl, A.ORC; Widera, R.; Pausch, R.; Garten, M.; Burau, H.; Matthes, A.; Worpitz, B.; Bastrakov, S.; Koller, F.; Kluge, T.; Vorberger, J.; Debus, A.; Cowan, T.; Schramm, U.; Chung, H.-K.; Bussmann, M.
Introduction into our open particle-in-cell code PIConGPU and research activities with it at HZDR.
Keywords: PIConGPU, open source, LPA
  • Invited lecture (Conferences)
    ILE Institute Seminar, 01.03.2018, Osaka, Japan

Publ.-Id: 27960 - Permalink


PIConGPU: Applications in Laser Ion Acceleration and Non-LTE Ionization Modeling
Huebl, A.ORC; Widera, R.; Pausch, R.; Burau, H.; Garten, M.; Matthes, A.; Debus, A.; Kluge, T.; Bussmann, M.
We present the scientific workflow and applications in plasma physics of the performance portable, open source, 3D3V electro-magnetic, many-core particle-in-cell (PIC) code PIConGPU. With an open and modern software environment, PIConGPU is already suited for the largest available supercomputers today and has now evolved to a single-source hardware independent PIC code running on conventional x86 architectures, upcoming OpenPOWER CPUs, many-core accelerators and as before, GPUs.
Keywords: PIConGPU, workflows, open science, 3D3V simulation, OpenPOWER, Alpaka, performance-portability, LPA, laser-plasma
  • Poster
    HZDR PhD Seminar, 16.-18.10.2017, Seiffen, Deutschland

Publ.-Id: 27959 - Permalink


Accelerating Accelerator Research for Radiation Therapy of Tumors with PIConGPU
Huebl, A.ORC; Kluge, T.; Schramm, U.; Bussmann, M.
Laser ion acceleration for tumor therapy requires control of the plasma acceleration process. Here we present the incredients of our first principle simulations, providing control, insight and predicting scaling laws towards efficient laser plasma acceleration.
Keywords: POF, PIConGPU, LPA, Laser-Ion Acceleration, Simulation, Accelerator, GPU
  • Poster
    POF Evaluation HZDR (Health), 09.-11.10.2017, Dresden, Deutschland

Publ.-Id: 27958 - Permalink


Next-Generation Simulations for XFEL-Plasma Interactions with Solid Density Targets with PIConGPU - Solutions for Predictive 3D Modeling
Huebl, A.ORC; Widera, R.; Pausch, R.; Garten, M.; Burau, H.; Koller, F.; Kluge, T.; Vorberger, J.; Debus, A.; Cowan, T.; Schramm, U.; Chung, H.-K.; Bussmann, M.
PIConGPU reportedly is the fastest particle-in-cell code in the world with respect to sustained Flop/s. Written in performance-portable, single-source C++ we constantly push the envelope towards Exascale laser-plasma modeling. However, solving previously week-long simulation tasks in a few hours with a speedy framework is only the beginning.

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

We present our ready-to-use open-source solutions and address scientific repeatability, data-reduction in I/O, predictability and new atomic modeling for XFEL pump-probe experiments.
Keywords: PIConGPU, exascale, xfel, hed, 3D simulations, laser-ion acceleration, lpa
  • Lecture (Conference)
    3rd European Advanced Accelerator Concepts Workshop, 24.-30.09.2017, Elba, Italien

Publ.-Id: 27957 - Permalink


Open the Exascale Tool Chest for Predictive Plasma Modelling with PIConGPU
Huebl, A.ORC; Widera, R.; Pausch, R.; Garten, M.; Burau, H.; Kluge, T.; Debus, A.; Vorberger, J.; Chung, H.-K.; Cowan, T.; Schramm, U.; Bussmann, M.
PIConGPU is reportedly the world's fastest, electro-magnetic 3D3V particle-in-cell code. With sustained multi-PFlop/s performance and demonstrated PByte-scale I/O performance 2 this open-source PIC code is able to fully exploit the computational power provided by leadership-scale manycore HPC systems. At the same time, modern single-source C++ meta-programming enables performance-portability without the need of rewriting or maintaining code for various programming models.

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

We present the architecture, open environment, open standards, community and physical models of our open-source software PIConGPU 4 and its applications in laser-plasma physics, XFEL-matter interaction and computational astrophysics.
Keywords: open source, exascale, picongpu, laser-plasma, pic, xfel, hed
  • Lecture (Conference)
    International Conference on Numerical Simulation of Plasmas, 18.-20.09.2017, Leuven, Belgium

Publ.-Id: 27956 - Permalink


Tuning the conductance of a molecular wire by the interplay of donor and acceptor units
Skidin, D.; Erdmann, T.; Nikipar, S.; Eisenhut, F.; Krüger, J.; Günther, F.; Gemming, S.; Kiriy, A.; Voit, B.; Ryndyk, D.; Joachim, C.; Moresco, F.; Cuniberti, G.
We investigate the conductance of optimized donor-acceptor-donor molecular wires obtained by on-surface synthesis on the Au(111) surface. A careful balance between acceptors and donors is achieved using a diketopyrrolopyrrole acceptor and two thiophene donors per unit along the wire. Scanning tunneling microscopy imaging, spectroscopy, and conductance measurements done by pulling a single molecular wire at one end are presented. We show that the conductance of the obtained wires is among the highest reported so far in a tunneling transport regime, with an inverse decay length of 0.17 Å-1. Using complex band structure calculations, different donor and acceptor groups are discussed, showing how a balanced combination of donor and acceptor units along the wire can further minimize the decay of the tunneling current with length.
Keywords: molecular electronics, density-functional, conductance, donor-acceptor polymer, DA polymer, STM, band structure, molecular wire

Downloads:

Publ.-Id: 27954 - Permalink


Broadband Terahertz Detection With Zero-Bias Field-Effect Transistors Between 100 GHz and 11.8 THz With a Noise Equivalent Power of 250 pW/√Hz at 0.6 THz
Regensburger, S.; Mukherjee, A. K.; Schönhuber, S.; Kainz, M. A.; Winnerl, S.; Klopf, J. M.; Lu, H.; Gossard, A. C.; Unterrainer, K.; Preu, S.
We demonstrate UV contact lithographically fabricated III–V field-effect transistors (FETs) examined over a bandwidth of 100 GHz–11.8 THz. The zero-bias device reaches a noise equivalent power as low as 250 pW/√Hz at 0.6 THz, which then increases as f^4 at higher frequencies. The responsivity is modeled by a simple equivalent circuit, showing good agreement over the frequency range of two decades. The FETs have been characterized using a photomixer, a quantum cascade laser, and a free-electron laser, proving the versatility and large applicability of the detection concept.
Keywords: THz detection, broadband detection, field-effect transistor

Downloads:

  • Secondary publication expected from 04.07.2019

Publ.-Id: 27949 - Permalink


openPMD Example Data Sets from PIConGPU 0.2.0
Huebl, A.ORC
Quite outdated data but used in openPMD-api unit tests.

HDF5 data contains particle patches, ADIOS1 data does not. Uploading it here for reference, as a download point and for test reproducibility.
Keywords: openPMD; example data
  • Reseach data in the HZDR data repository RODARE
    Publication date: 2018-09-19
    DOI: 10.14278/rodare.57
    License: CC-BY-4.0

Downloads:

Publ.-Id: 27948 - Permalink


Beitrag zur Erkundung und metallgenetischen Charakteristik der Li-Sn-W-Greisenlagerstätte Zinnwald, Osterzgebirge, Deutschland
Neßler, J.; Seifert, T.; Gutzmer, J.; Müller, A.
Die Lagerstätte Zinnwald gehört zu den bedeutendsten Greisenlagerstätten der zentraleuroäischen Varisziden, die nach einem über mehrere Jahrhunderte währenden historischen Bergbau auf Sn- und W-Erze erneute rohstoffkundliche Bedeutung hinsichtlich ihrer Li-Ressourcen erlangt hat. Im Zuge einer internationalen Bewertungskriterien entsprechenden Explorationskampagne wurde die Lagerstätte zwischen 2011 und 2014 auf Li-Sn- und W- führende Greisenerze erkundet, welche im obersten Teil der grenzüberschreitenden Granitintrusion von Zinnwald entwickelt sind.
Auf Grundlage historischer Erkundungsergebnisse und insgesamt neun im Projektzeitraum abgeteufter Kernbohrungen (Gesamtlänge ca. 2480 m) war es möglich neben der Abschätzung der Li-Ressourcen generelle Charakteristika zur Ausbildung der Greisenmineralisation im deutschen Lagerstättenteil abzuleiten. Ein wesentliches Ergebnis liegt in der Bestätigung der strukturell kontrollierten Lagerstättenarchitektur vor, welche eine flach fallende und generell dem Granitkontakt folgende Lagerung der Greisenerzkörper im Endokontakt entlang subhorizontaler Abkühlungsklüfte vorsieht. Während der Hauptanteil der Li-Mineralisation im zentralen Scheitelbereich der albitgranitischen Intrusion ausgebildet ist, konnte mit Hilfe der aktuellen Bohrungen der Nachweis einer weiteren Hauptvererzungszone mit bis zu 50 m mächtigen Greisenkörpern entlang der Ostflanke erbracht werden. Ein weiteres Ergebnis von außerordentlicher metallogenetischer und möglicherweise ökonomischer Bedeutung stellt die Entdeckung einer kontinuierlich mineralisierten Zone disseminierter Sn-W-Vererzung von schwach vergreistem Albitgranit im Liegenden der Greisenerze dar. Mit einer scheinbaren Mächtigkeit von 20 m lässt sich diese im Liegenden der Greisenkörper über eine streichende Erstreckung von mindestens 700 m nachweisen.
Die chemische Zusammensetzung der Gesteine und Erze im Endo- bzw. Exokontakt wurde anhand von über 1300 Multielementanalysen von Bohrkern- und untertägigen Schlitzproben bestimmt. Der geochemisch bereits stark spezialisierte Charakter der Granitintrusion von Zinnwald hat im Zuge der metasomatischen Vergreisungsprozesse eine weitere Vervielfachung der Konzentrationswerte, insbesondere für F, Fe, Li, Rb, Cs, Zn sowie Sn, W und Mo, erfahren. Während die Erzelemente Li und W keine systematischen Veränderungen über den Teufenbereich der Vergreisung zeigen, deuten die Sn-Konzentrationen in Greisen und vergreisten Albitgranit auf eine deutliche Abnahme mit zunehmender Entfernung zum Endokontakt.
Das Haupterzmineral der Li-Mineralisation stellt das trioktaedrische Schichtsilikat Zinnwaldit dar, welches mit durchschnittlich 25 Vol. % am Modalbestand typischer Greisen beteiligt ist. Neben Li Gehalten zwischen 1,1 und 2,3 Gew. % deuten umfangreiche Untersuchungen mittels EPMA und LA-ICP-MS auf stark variierende, teufenabhängige und für einzelne Gesteinsproben individuelle Ti Sn-Verhältnisse hin. Die Ergebnisse demonstrieren eine gute Übereinstimmung und Fortsetzung geochemischer Trends mit Literaturdaten aus tieferen Bereichen des Granitstocks von Zinnwald/Cínovec und können als Hinweis auf die Spurenelementänderung mit der Transformation von Protolithionit zu Zinnwaldit sowie auf eine erneute Anreicherung von Sn im Kristallgitter der Zinnwalditkörner im obersten, Hauptverer-zungsbereich angesehen werden.
Im Rahmen der vorgestellten Arbeit wurden Zinnwalditseparate aus Greisenerzen, Greisengängen und unvererztem Nebengestein mittels 40Ar/39Ar-Altersbestimmung datiert. Alle Proben deuten im Ergebnis auf ein einheitliches Alter von 312,8±1,8 Ma, welches als Alter der Vergreisung und der damit einhergehenden Bildung von oder Verdrängung durch Zinnwaldit interpretiert wird.
Die Ergebnisse dieser Arbeit tragen damit zu einem bedeutenden Kenntniszuwachs des Lagerstättenpotentials sowie zum besseren Verständnis von Architektur, Zusammensetzung und zeitlicher Einstufung der Gesteine und Erzmineralisation bei. Die genetischen Implikationen erweitern die generellen Vorstellungen der lagerstättenbildenden Prozesse und können somit hilfreich für weitere Explorationsarbeiten innerhalb der Lagerstätte sowie in anderen granitgebundenen Greisenlagerstätten sein. Weiterhin deuten die Ergebnisse auf einen der metasomatischen Bildung von Li-Glimmergreisen stofflich und evtl. auch zeitlich abweichenden Sn-W-Mineralisationsprozess hin.
Während die Rohstofferkundung die Bedeutung der Lagerstätte Zinnwald als eine der größten Li-Lagerstätten Europas
Keywords: Zinnwald, Erzgebirge, Lithium, Zinn, Metallogenese, Greisen
  • Book (Authorship)
    Freiberg: TU Bergakademie Freiberg, 2017

Publ.-Id: 27944 - Permalink


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

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

Keywords: moulded wood tube; gamma-ray computed tomography
  • Reseach data in the HZDR data repository RODARE
    Publication date: 2018-09-18
    DOI: 10.14278/rodare.54

Downloads:

Publ.-Id: 27941 - Permalink


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

Downloads:

Publ.-Id: 27939 - Permalink


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

[1] X. Yang et al., Phys. Chem. Chem. Phys., accepted (2018).
Keywords: electrolysis, gas evolution, Marangoni effect, convection, numerical simulation
  • Lecture (Conference)
    12. European Fluid Mechanics Conference, 09.-13.09.2018, Wien, Österreich

Publ.-Id: 27935 - Permalink


Convection and mass transfer near a hydrogen bubble evolving during water electrolysis in magnetic fields
Mutschke, G.; Yang, X.; Eckert, K.; Uhlemann, M.; Baczyzmalski, D.; Cierpka, C.
Hydrogen produced from wind or solar power could be used easily for storing energy also at large scale, thus allowing to bridge the gap between supply and demand of renewable energy with respect to time and place. When splitting water by electrolysis, a deeper look at local phenomena near single bubbles at the electrode might be helpful to improve our understanding of this process. In the recent literature, magnetic fields are discussed with respect to the bubble departure, thereby possibly influencing the efficiency of the process [1-5].
The contribution will present numerical simulations resolving in detail local phenomena near a single hydrogen bubble evolving at a small circular cathode during the electrolysis of water. The results are compared with experimental data of hydrogen evolution at a platinum micro-electrode. Hereby, the influence of the Lorentz force caused by vertical and horizontal magnetic fields will be discussed. The results presented will provide insight into electrolyte convection, species concentration, mass transfer and on the bubble departure [6-8].
Keywords: electrolysis, gas evolution, convection, mass transfer, magnetic field, Lorentz force, numerical simulation
  • Lecture (Conference)
    12. European Fluid Mechanics Conference, 09.-13.09.2018, Wien, Österreich

Publ.-Id: 27934 - Permalink


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

Publ.-Id: 27932 - Permalink


Hydrometallurgy @ HIF
Gutzmer, J.
Hydrometallurgical research of HZDR will be presented in this contribution. .An overview will be provided on relevant hydrometallurgical research carried out in Freiberg and in Dresden. The progress of collaborative research projects will be documented and preliminary results presented. A particular focus will be set on the development of pilot plant-scale research facilities and the opportunities this offers for future research.
Keywords: Hydrometallurgy, HZDR
  • Invited lecture (Conferences)
    BASF Innovation Day, 13.-14.09.2018, Ludwigshafen, Germany

Publ.-Id: 27931 - Permalink


Fourier Analysis of Cerebral Metabolism of Glucose Revealed Gender Differences in Ventral and Dorsal Streams for Colour Processing in Mice
Njemanze, P.; Kranz, M.; Brust, P.
Fourier analysis of regional cerebral metabolic rate of glucose (CMRglc) as estimated by measurement of standardized uptake values (SUVs) of [18F]fluorodeoxyglucose ([18F]FDG) using functional positron emission tomography magnetic resonance imaging (fPET/MRI) revealed activation patterns during white light and colour stimulation in male and female mice, respectively. Spectral density curves of the cortical and subcortical peaks demonstrated wavelength-differencing for luminance and chromatic opponency in the ventral stream in male mice, but frequency-differencing in the dorsal stream in female mice. Male mice demonstrated subcortico-cortical bottom-up feed-forward system for light and colour processing, while in female mice there was a cortico-subcortical top-bottom feed-back system.
Fourier time series analysis was helpful to improve both spatial and temporal resolution of PET/MRI for study of colour processing in the visual system. It demonstrated computation of colour processing as conscious experience, and has a wide range of applications including in artificial intelligence and quantum mechanics.
Keywords: chromatic opponency, sex differences, light wave, light particle, blood flow, frequency, resonance
  • Contribution to proceedings
    ITISE 2018 (International conference on Time Series and Forecasting), 19.-21.09.2018, Granada, Espana
    Proceedings of the International conference on Time Series and Forecasting, Granada: Godel Impresiones Digitales S.L., 978-84-17293-57-4

Publ.-Id: 27930 - Permalink


Simulation based LCA – Digitalizing the Circular Economy - Its simulation with two cases: eWaste & batteries/Zn fuming
Reuter, M. A.
Circular Economy (CE)
-The origins
Circular Economy Engineering (CEE)
Metallurgical Internet-of-Things (m-IoT)
-Comprehensive flowsheets that integrate product design with physical separation and process metallurgy
Informing Resource Efficiency (iRE)
-Case 1: Fairphone
-Case 2: Plasma furnace for battery smelting & fuming
Additional Sheets
-Case 3: Recycling of LED lamps / Literature / More detailed sheets
Keywords: Circular Economy, Sustainability, Circular Economy Engineering, thermoeconomics, recycling, Metallurgical Internet of Things, Metal Wheel, Digitalizing
  • Lecture (others)
    HSC 9 Life Cycle Assessment for Process Industry // Training Courses, 03.-05.06.2018, Pori, Finnland

Publ.-Id: 27929 - Permalink


Experimental study of liquid velocity profiles in large-scale bubble columns with particle tracking velocimetry
Besagni, G.; Inzoli, F.; Ziegenhein, T.; Lucas, D.
A complete knowledge of bubble column fluid dynamics relies on understanding both the “global-scale” and the “local-scale” phenomena and coupling between the phases. Unfortunately, most of the previous literature focused on the “global-scale” fluid dynamics, whereas a limited attention was devoted to the “local-scale” fluid dynamics. In this study, we contribute to the present-day discussion through an experimental study concerning the local liquid velocity field in the pseudo-homogeneous flow regime. The experimental study, based on a particle-identification and particle-tracking algorithm, was conducted in a large-diameter and large-scale air-water bubble column (with a height of 5.3 m and inner diameter of 0.24 m) operated in the counter-current mode. We considered gas superficial velocities in the range of 0.37–1.88 cm/s and liquid superficial velocities up to −9 cm/s. The time-averaged and the transient liquid velocity field were obtained and critically discussed for five superficial gas velocities and four superficial liquid velocities at two measuring heights. Subsequently, the local locally resolved information concerning the liquid velocity were coupled with the previously measured bubble size distributions and local void fractions, to provide a complete description of the “local-scale” fluid dynamics. In addition, these data would help in the validation of numerical codes to predict industrial-scale relevant conditions.
Keywords: bubbly column, pilot scale, experiment
  • Contribution to proceedings
    36th UIT Heat Transfer Conference, 25.-27.06.2018, Catania, Italy
  • Lecture (Conference)
    36th UIT Heat Transfer Conference, 25.-27.06.2018, Catania, Italy

Publ.-Id: 27928 - Permalink


Multi-fluid models for gas-liquid flows
Lucas, D.; Krepper, E.; Liao, Y.; Höhne, T.; Rzehak, R.; Schlegel, F.; Ziegenhein, T.
The two- or multi-fluid approach is frequently used for NRS-related simulations of gas-liquid flows. To enable reliable predictions the closure models have to reflect the involved local physical phenomena at the non-resolved scale properly. To consolidate the CFD-modelling in the frame of the multi-fluid approach the so-called baseline model strategy was recently proposed (Lucas et al., 2016). The paper discusses a long-term strategy for the baseline model development and ways to obtain or improve closure models. Guidelines for the model development are given by listing requirements for appropriate closure models as well as frequently made mistakes. This is illustrated by examples for recent developments done for HZDR baseline models for poly-disperse bubbly and segregated flows. Beside an update on recent developments ongoing and planned activities are discussed. Both models are united in the GENTOP-concept which allows simulating flow pattern transitions. Finally, perspectives for the use of OpenFOAM for NRS are discussed.
Keywords: CFD, multiphase, closure model, validation
  • Contribution to proceedings
    OECD/NEA&IAEA CFD4NRS-7 Workshop Application of CFD/CMFD Codes to Nuclear Reactor Safety and Design and their Experimental Validation, 04.-06.09.2018, Shanghai, China
  • Lecture (Conference)
    OECD/NEA&IAEA CFD4NRS-7 Workshop Application of CFD/CMFD Codes to Nuclear Reactor Safety and Design and their Experimental Validation, 04.-06.09.2018, Shanghai, China

Publ.-Id: 27927 - Permalink


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

1 J.P. Couperus et al., “Demonstration of a beam loaded nanocoulomb-class laser wakefield accelerator”, Nature Communication, 8, 487 (2017)
2 A. Irman et al., “Improved performance of laser wakefield acceleration by tailored self-truncation ionization injection”, Plasma Physics and Controlled Fusion, 60, 044015 (2018)
Keywords: Laser Wakefield Acceleration, LWFA, Beam loading, Electron acceleration
  • Lecture (Conference)
    Advanced Accelerators Concepts Workshop, 13.-17.08.2018, Breckenridge, Colorado, USA

Publ.-Id: 27926 - Permalink


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

Downloads:

Publ.-Id: 27925 - Permalink


State of the Art Design for Recycling: Case Fairphone
Reuter, M. A.
- Circular Economy (CE)
- Circular Economy Engineering (CEE)
- Metallurgical Internet-of-Things (m-loT)
- informing Resource Efficieny (iRE) - Fairphone
- Additional Sheets - Recycling of LED lamps/Literature/More detailed sheets
Keywords: Circular Economy, Circular Economy Engineering, Metallurgical Internet-of-Things, Resource Efficieny, Fairphone, Recycling
  • Invited lecture (Conferences)
    Recycling Metals from Industrial Waste - Anual Short Course / Workshop, 26.-29.06.2018, Golden Colorado, USA

Publ.-Id: 27924 - Permalink


Die Digitalisierung der Kreislaufwirtschaft - Wie recyclebar sind Smartphones?
Reuter, M. A.
Circular Economy (CE)
Circular Economy Engineering (CEE)
Metallurgical Internet-of-Things (m-IoT)
informing Resource Efficiency (iRE)
Keywords: Circular Economy, Circular Economy Engineering, Metallurgical Internet-of-Things, Resource Efficiency
  • Lecture (others)
    Intelligente Kreislaufwirtschaft - Aktuelle Aspekte zu Recycling, Aufbereitung und Fernerkundung / Lehrerfortbildung, 16.02.2018, Freiberg, Deutschland

Publ.-Id: 27923 - Permalink


Simulation based footprint of technology
Reuter, M. A.
Overview of Circular Economy in the Metallurgical Processing Industry
Introduction into HSC / into Simulation Based Footprinting / of Case: Processing of slag in a plasma furnace
Completion of Case
Environmental impact assessment using HSC Sim and GaBi
Keywords: Circular Economy, Resource Efficiency, Recycling, Sustainability, Circular Economy Engineering, Fairphone
  • Lecture (others)
    EIT KIC Workshop, 15.-17.05.2018, Freiberg, Deutschland

Publ.-Id: 27922 - Permalink


Thermoeconomic Analysis of a Copper Production Plant - From Mine to Cathode
Reuter, M. A.; Llamasa, A. A.; Stelter, M.; Valero Delgado, A.; Hultgren, M.; Peltomäki, M.; Roine, A.
- Introduction Circular Economy
- Exergy as a resource consumption indicator
- Thermoeconomics
- Simulation-based exergy and thermoeconomic analysis
- Extractive metallurgy of copper case
- Conclusions
Keywords: Circular Economy, Thermoeconomics
  • Invited lecture (Conferences)
    Sustainable Minerals '18 - Towards a circular economy // MEI Conference, 14.-15.06.2018, Windhoek, Namibia

Publ.-Id: 27920 - Permalink


The Circular Economy - Challenges, Opportunities, Limits
Reuter, M. A.
- Circular Economy (CE) + the origins
- Circular Economy Engineering (CEE) + System Integrated Metal Production (SIMP)
- Metallurgical Internet-of-Things (m-loT)
+ Comprehensive flowsheets that integrate product design with physical separation and process metallurgy
+ LED lamps
- informing Resource Efficiency (iRE)
+ Fairphone
Keywords: Circular Economy, Circular Economy Engineering, Metallurgical Internet-of-Things, Resource Efficiency, Fairphone
  • Lecture (others)
    Circular Economy Design Forum, 28.03.2018, Espoo, Finnland

Publ.-Id: 27918 - Permalink


Opportunities and limits of the Circular Econonmy – A metallurgical perspective.
Reuter, M. A.
Rock-to-Metal digitalized and linked to Energy is the Music
The Metal Wheel – A deep understanding is required
Metallurgical Infrastructure Criticality; not only Metal / Element Criticality
Digitalization of the Circular Economy & Analysis
Analyzing the CE system to understand economically the losses on a simulation basis using thermoeconomics & LCA
EU’s Metal Wheel: Develop thermodynamic detail
The Limits of Recycling: Modular design pushing limits
Keywords: Exergy, LCA, thermo-economics, Fairphone, Digitalization
  • Invited lecture (Conferences)
    12th Society And Materials International Conference - SAM 12, 22.-23.05.2018, Metz, Frankreich

Publ.-Id: 27915 - Permalink


No growth without raw materials: Europe must maintain and develop production and recycling technologies.
Reuter, M. A.
The aim of the seminar should be to define the role of regions in shaping a holistic industrial strategy for the EU, particularly with regard to innovation, digitalisation and global competition.
Through a smart, sustainable and inclusive industrial policy, innovative ecosystems are to be promoted in the regions, entrepreneurship encouraged, and jobs created.
Regulatory barriers will need to be dismantled, sustainability ensured, European technological sovereignty preserved and fairness achieved in global competition. To this end, the experience and knowledge of the regions and their proposals for a future EU industrial strategy are indispensable.
The example of Saxony can be used to demonstrate the progress made towards “Industry 4.0” in the fields of microelectronics, e-mobility, material efficiency/resource technologies and advanced manufacturing.
  • Invited lecture (Conferences)
    ECON external Seminar on "Shaping change — towards a holistic industrial strategy", 02.-03.05.2018, Dresden, Deutschland

Publ.-Id: 27914 - Permalink


Simulation based life cycle assessment of metallurgical and recycling processes
Reuter, M. A.
Process simulation and environmental softwareare applied to quantify resource efficiency (RE) in a rigorous manner. These digitalisation tools are linked and will be used to show how the environmental performance of copper primary production, the processing of residues and the recycling of e-waste, e.g. light emitting diode (LED) lamps as well as the production of nickel pig iron can be evaluated.
Keywords: HSC, design for recycling, Fairphone, process simulation, recyclability
  • Invited lecture (Conferences)
    Life Cycle Assessment Symposium, 27.04.2018, Freiberg, Deutschland

Publ.-Id: 27911 - Permalink


Limits of the circular economy: Fairphone modular design pushing the limits
Reuter, M. A.; Ballester, M.; van Schaik, A.
The limitations to materials flows from recycling in the circular economy are discussed using as a case a simulation-based analysis of the recyclability of the Fairphone 2. Three different recycling routes are analysed using simulation models that link the bill of materials and full material declarations to the final metal recovery via physical separation models. The recycling and recovery rates are depicted in an innovative recycling index and material flower that helps drive the discussion about the inevitable tradeoffs between the recyclability of different target materials and debunks the myth of a total recyclability of materials. Modular design is shown to have clear recycling as well as environmental advantages. This study is part of the SustainablySMART project.This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 680640. © 2018 GDMB Gesellschaft fur Bergbau, Metallurgie, Rohstoff- und Umwelttechnik e.V. All rights reserved.
Keywords: Circular economy, Design for recycling, Fairphone, Recycling-index, Simulation
  • Invited lecture (Conferences)
    Sustainable Minerals '18 - Towards a circular economy // MEI Conference, 14.-15.06.2018, Windhoek, Namibia

Publ.-Id: 27909 - Permalink


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

#Geometallurgy18
Geometallurgy is now largely accepted as the process to quantify and understand a mineral deposit in terms of its structure, composition and ultimately to determine its economic value.
Geometallurgy 2018 will bring together experts from academia and industrial research, practitioners from operating mines, consultants and contractors as well as industry bodies with the aim of increasing the understanding and value of mineral assets.
Keywords: Circular economy, digitalization, metallurgy, recycling, resource efficiency
  • Invited lecture (Conferences)
    GEOMETALLURGY 2018, 19.-20.04.2018, London, Großbritannien

Publ.-Id: 27906 - Permalink


Redirecting switchable UniCAR T cells for elimination of radioresistant cancer cells
Feldmann, A.; Arndt, C.; Bergmann, R.; Berndt, N.; Jureczek, J.; Albert, S.; Lindner, D.; Koristka, S.; Steinbach, J.; Ehninger, G.; Krause, M.; Kurth, I.; Dubrovska, A.; Bachmann, M.
Radiation therapy represents a commonly applied treatment regimen for solid tumors. Unfortunately, it is often accompanied by a high risk for the outgrowth of radioresistant cancer cells against which treatment options are limited. We challenged the idea whether or not chimeric antigen receptor (CAR)-modified T cells could be exploited as an adjuvant immunotherapy in combination with standard radiotherapy. Over the past several years, we have established switchable universal CAR constructs (UniCARs) that recognize a short peptide epitope (E5B9) which does not exist on the surface of living cells. UniCAR T cells are redirected to malignant cells exclusively in the presence of a target module (TM) that contains the epitope E5B9 and specifically binds to a tumor-associated antigen (TAA) on the tumor cell surface.
For providing a rationale for the combination of CAR and radiation therapy, we used different radioresistant sublines of the head and neck cancer cell line Cal33. Expression of various TAAs including of PSCA, EGFR and CD98 was confirmed by flow cytometry analysis. Subsequently, TMs recognizing these potential targets were generated from the variable domains of monoclonal antibodies, cloned into lentiviral vectors and purified from cell culture supernatants of TM-producing stable cell lines. In parallel, T cells isolated from healthy donors were engrafted with UniCARs by lentiviral transduction. Armed with our anti-TAA TMs, UniCAR T cells efficiently lysed radioresistant Cal33 tumor cells both in vitro and in vivo.
Taken together, we could demonstrate that radioresistant cancer cells can effectively be killed by retargeting UniCAR T cells against PSCA, CD98 and EGFR. Thus, resistance to standard of care radiotherapy can be overcome by concomitant or subsequent immunotherapy using the flexible UniCAR technology.
Keywords: radiation therapy, immunotherapy, chimeric antigen receptors
  • Lecture (Conference)
    ICLE 2018, International Conference on Lymphocyte Engineering 2018, 13.-15.09.2018, Madrid, Spanien

Publ.-Id: 27904 - Permalink


Directionality of nickel-induced layer exchange during graphitization in carbon-nickel thin films
Janke, D.; Wenisch, R.; Munnik, F.; Hübner, R.; Grenzer, J.; Gemming, S.; Rafaja, D.; Krause, M.
Metal-induced crystallization with layer exchange (MIC w LE) can reduce the crystallization temperature of group 14 elements by several hundred degrees. This is especially interesting for device fabrication on substrates with limited thermal stability. Ideally, the process allows the transfer of defined amounts of an initially amorphous material onto a randomly selected substrate. In this contribution, MIC w LE is studied for Ni/ a-C thin films with different stacking sequences in order to quantify the influence of the stacking sequence on the layer exchange degree αLE and on the degree of graphitic ordering. The process was monitored in situ by temperature-dependent Rutherford backscattering spectrometry (RBS) and Raman spectroscopy up to 700 °C. RBS, Raman, elastic recoil detection, X-ray diffraction and transmission electron microscopy were applied for ex situ characterization.
The highest αLE of 96% was found for the initial Ni/a-C stacking sequence. In contrast, the inverse sequence resulted in an incomplete LE. The formation of 2D-layered carbon structures occurred independently of the initial stacking sequence.1 Beyond the threshold of 580 °C, increasing the temperature to up to 700 °C had a negligible impact on the degree of 2D-ordering. Since LE and graphitization occur simultaneously at high temperatures, MIC w LE rather than dissolution/ precipitation is proposed as responsible mechanism for carbon crystallization.
Keywords: metal-induced crystallization, directionality, amorphous carbon, nickel, graphitization, layer exchange, ERD, Raman, TEM
  • Lecture (Conference)
    Flatlands 2018, 03.-07.09.2018, Leipzig, Deutschland

Publ.-Id: 27903 - Permalink


Digitalizing the Circular Economy - Metallurgical process system is the carrier
Reuter, M. A.
Metallurgy is a key enabler of a circular economy (CE), its digitization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure.
Keywords: circular economy, digitization, recycling, resource efficiency, sustainability
  • Invited lecture (Conferences)
    8th Forum of Non-Ferrous Metals, 21.-23.02.2018, Krakau, Polen

Publ.-Id: 27902 - Permalink


Digitalizing the Circular Economy - Fairphone as example
Reuter, M. A.
The limitations to materials flows from recycling in the circular economy are discussed using as a case a simulation-based analysis of the recyclability of the Fairphone 2. Three different recycling routes are analysed using simulation models that link the bill of materials and full material declarations to the final metal recovery via physical separation models. The recycling and recovery rates are depicted in an innovative recycling index and material flower that helps drive the discussion about the inevitable trade-offs between the recyclability of different target materials and debunks the myth of a total recyclability of materials. Modular design is shown to have clear recycling as well as environmental advantages. This study is part of the SustainablySMART project.
Keywords: Circular Economy – Design for Recycling – Fairphone – Simulation – Recycling-Index
  • Invited lecture (Conferences)
    Circular Materials Conference, 07.-08.03.2018, Göteborg, Schweden

Publ.-Id: 27901 - Permalink


Simulation based Design for Recycling - Fairphone as an example
Reuter, M. A.
The limitations to materials flows from recycling in the circular economy are discussed using as a case a simulation-based analysis of the recyclability of the Fairphone 2. Three different recycling routes are analysed using simulation models that link the bill of materials and full material declarations to the final metal recovery via physical separation models. The recycling and recovery rates are depicted in an innovative recycling index and material flower that helps drive the discussion about the inevitable tradeoffs between the recyclability of different target materials and debunks the myth of a total recyclability of materials. Modular design is shown to have clear recycling as well as environmental advantages. This study is part of the SustainablySMART project.
Keywords: Circular Economy – Design for Recycling – Fairphone – Simulation – Recycling-Index
  • Invited lecture (Conferences)
    Berliner Recycling- und Rohstoffkonferenz, 19.03.2018, Berlin, Deutschland

Publ.-Id: 27900 - Permalink


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

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

In another project, we are using deep learning approaches to develop an automated safety system for the high-power laser systems DRACO and PENELOPE at HZDR. Here the goal is to detect defects or scatterers which focus parts of a yet unfocussed beam. These can, when left unchecked, cause cascades of failing mirrors, lenses, and non-linear crystals and should thus be detected in the time between two shots. This work uses deep convolutional neural networks implemented through the Caffe framework to achieve real-time detection and localization of impurities in the beam profile.
Keywords: computational science, data management, machine learning
  • Lecture (Conference)
    IHRS NanoNet Annual Workshop, 05.-07.09.2018, Bad Gottleuba, Deutschland

Publ.-Id: 27897 - Permalink


Extended Infrared Photoresponse in Te-Hyperdoped Si at Room Temperature
Wang, M.ORC; Berencén, Y.; García-Hemme, E.; Prucnal, S.; Hübner, R.; Yuan, Y.; Xu, C.; Rebohle, L.; Böttger, R.; Heller, R.; Schneider, H.; Skorupa, W.; Helm, M.; Zhou, S.
Presently, silicon photonics requires photodetectors that are sensitive in a broad infrared range, can operate at room temperature, and are suitable for integration with the existing Si-technology process. Here, we demonstrate strong room-temperature sub-band-gap photoresponse of photodiodes based on Si hyperdoped with tellurium. The epitaxially recrystallized Te-hyperdoped Si layers are developed by ion implantation combined with pulsed-laser melting and incorporate Te-dopant concentrations several orders of magnitude above the solid solubility limit. With increasing Te concentration, the Te-hyperdoped layer changes from insulating to quasi-metallic behavior with a finite conductivity as the temperature tends to zero. The optical absorptance is found to increase monotonically with increasing Te concentration and extends well into the mid-infrared range. Temperature-dependent optoelectronic photoresponse unambiguously demonstrates that the extended infrared photoresponsivity from Te-hyperdoped Si p-n photodiodes is mediated by a Te intermediate band within the upper half of the Si band gap. This work contributes to pave the way toward establishing a Si-based broadband infrared photonic system operating at room temperature.

Downloads:

Publ.-Id: 27886 - Permalink


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