Mobile version: On

Publication database - Helmholtz-Zentrum Dresden-Rossendorf

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

< Seite 1 von 185 >   Gesamtzahl lt. Auswahl: 18495 Title records (100 Title records je Seite)
22781 Publications
Geometallurgy of REE deposits - state of the art
Renno, Axel D.; Gutzmer, J.; Birtel, S.; Atanasova, P.; Bachmann, K.; Matos Camacho, S.; Schulz, B.; Kern, M.; Krause, J.; Munnik, F.
Abstract: Review of the most recent activities of the Helmholtz-Institute Freiberg for Resource Technology in the field of geometallurgy of REE deposits
Keywords: geometallurgy, REE
  • Invited lecture (Conferences):
    Geology to Metallurgy of Critical Rare Earths, 24.-25.03.2014, Penryn, UK
Registration No. 20916

High-Speed PIXE – a new tool for Automated Mineralogy using a Color X-Ray Camera
Renno, Axel D.; Buchriegler, J.; Dressler, S.; Hanf, D.; Merchel, S.; Munnik, F.; Nowak, S.; Scharf, O.; Ziegenrücker, R.
Abstract: Methods of automated mineralogy form the analytical backbone of geometallurgy. Most of them exploit the combined imaging and analytical capabilities of optical and scanning electron microscopes. Typical results are „phase maps“ either derived from the distribution of major elements or determined directly. The effective application of such methods for strategic metals which are won as by-products from other metal ores or secondary raw materials is handicapped by the restricted possibilities to determine the spatial distribution of such trace elements like In, Ga, Ge or the rare earth elements (REE). The recently commissioned High-Speed PIXE (Particle Induced X-Ray Emission) setup at the Helmholtz-Institute Freiberg for Resource Technologies will overcome these limitations by using the advantages of PIXE over traditional
electron beam based methods like the better peak-background ratio. We use the SLcam® Colour X-ray Camera - a novel pnCCD pixel detector (264×264=69696 pixel) combined with a polycapillary X-ray optics (Scharf et al., 2011) as detector for element specific X-ray radiation. This design allows us the simultaneous determination of trace element distributions on a 12 × 12 mm2 area with a lateral resolution better than 100 μm. First results of geometallurgical applications of this method are presented.

Keywords: PIXE, High-Speed PIXE
  • Lecture (Conference):
    92nd Annual Meeting Deutsche Mineralogische Gesellschaft (DMG) 2014, 21.-24.09.2014, Jena, Deutschland
Registration No. 20914

High field THz sources operating at 100 kHz Repetition rates: Challenges and Opportunities
Gensch, Michael
Abstract: Picosecond long transients of electric and magnetic
fields in combination with repetition rates in the few 100 kHz to even
MHz regime is crucial to understand several recently observed
fascinating nonequilibrium phenomena driven by THz excitations. A new
class of compact accelerator based THz sources based on super-radiant
amplification of radiation from ultra-short electron bunches allows to
generate high field THz pulses at unprecedented repetition rates.
First measurements at a prototype facility proof the feasibility of
the approach and demonstrate already parameters which exceeds
laser-based sources by more than 2 orders of magnitude. Results from first pilot
experiments aiming at investigating THz driven magnetization dynamics in MnGa, NiO
and YIG are discussed and an outlook into the opportunities for High-field THz science at the future TELBE
user facility is given.
  • Invited lecture (Conferences):
    Seminar of the Stanford Institute for Materials and Energy Sciences, 12.09.2014, Stanford / SLAC, USA
Registration No. 20913

High-Speed PIXE: Automated Mineralogy using a Color X-Ray Camera
Renno, Axel D.; Buchriegler, J.; Hanf, D.; Munnik, F.; Nowak, S.; Scharf, O.; Ziegenrücker, R.
Abstract: Methods of automated mineralogy form the analytical backbone of geometallurgy. Most of them exploit the combined imaging and analytical capabilities of optical and scanning electron microscopes. Typical results are „phase maps“ either derived from the distribution of major elements or determined directly. The effective application of such methods for strategic metals which are won as by-products from other metal ores is handicapped by the restricted possibilities to determine the spatial distribution of such trace elements like In, Ga, Ge or the rare earth elements (REE). The recently comissioned High-Speed PIXE (Particle Induced X-Ray Emission) setup at the Helmholtz-Institute Freiberg for Resource Technologies will overcome these limitations.
We use the SLcam® X-ray Color Camera - a novel pnCCD Pixel detector (264 x 264 = 69696 Pixel) combined with a polycapillary X-ray optic (Scharf et al., 2011) as the detector for the element specific X-ray radiation. This design allows us the simultaneous determination of the trace element distribution on a 12 * 12 mm2 area with a lateral
resolution of about 50 μm. First results of geometallurgical applications of this method are presented.

Keywords: PIXE, High-Speed PIXE
  • Lecture (Conference):
    21st General Meeting of the International Mineralogical Association, 01.-05.09.2014, Sandton, South Africa
Registration No. 20912

Assessments of boundary conditions and requirements for Rare Earth Underground Mining due to presence of NORMs
Barakos, G.; Mischo, H.; Gutzmer, J.
Abstract: Rare earths contain NORMs, such as uranium, thorium and their progeny, like radium and radon. The varying concentrations of NORMs are quite often significant enough to result in occupational and environmental radiation exposures during the mining, milling and processing procedures of rare earths and compounds. Ventilation is the primary technique of controlling ambient concentrations of radon. Fresh air volume flow rates, the distribution of airflow within the mine and the radon emanation rate are primary factors affecting such concentrations. In this paper, it is attempted to determine the factors that may result in radiation risks and evaluate the boundary conditions that will contribute to the restriction or even elimination of radon progeny, with a goal to use the evaluations in order to build an overall assessment tool.
Keywords: Rare Earth Elements, NORMs, Radon, Thoron, Underground Mining, Occupational Safety
  • Contribution to proceedings:
    ERES 2014 - 1st International Conference on European Rare Earth Resources, 04.-07.09.2014, Milos Island, Greece
    ERES 2014 - 1st International Conference on European Rare Earth Resources, Imerovigli, Santorini GR‐84700: Heliotopos Conferences Ltd., 978‐960‐6746‐15‐4
Registration No. 20904

Simulation of aerosol particle deposition and resuspension in high temperature reactors
Lecrivain, G.; Hampel, U.
Abstract: In a high temperature pebble-bed reactor core where thousands of pebbles are amassed, the friction between the outer graphite layer of the fuel elements triggers the formation of carbonaceous dust. This dust is eventually conveyed by the cooling carrier phase in the primary circuit of the high temperature reactor. Depending on the gas velocity, the solid aerosol particles can either attach to the wall surfaces or be re-entrained in the turbulent flow. Two numerical models developed for the prediction of particle attachment and detachment are presented.
  • Invited lecture (Conferences):
    Seminar / Commissariat à l’énergie atomique / Invited lecture, 20.06.2014, Saclay, France
Registration No. 20903

Simulation of aerosol particle deposition in a high temperature reactor
Lecrivain, G.; Hampel, U.; Hurtado, A.
Abstract: In a high temperature pebble-bed reactor core where thousands of pebbles are amassed, the friction between the outer graphite layer of the fuel elements triggers the formation of carbonaceous dust. This dust is eventually conveyed by the cooling carrier phase in the primary circuit of the high temperature reactor. Depending on the gas velocity, the solid aerosol particles can either attach to the wall surfaces or be re-entrained in the turbulent flow. Two numerical models developed for the prediction of particle attachment and detachment are presented.
  • Contribution to proceedings:
    Workshop des CFD-Kompetenzverbunds / German CFD Network, 19.-20.03.2014, Garching, Germany
    Proceedings of the German CFD Network
Registration No. 20902

Surface and Material Analytics based on Dresden-EBIS Platform Technology
Schmidt, M.; König, J.; Bischoff, L.; Pilz, W.; Zschornack, G.
Abstract: Nowadays widely used mass spectrometry systems utilize energetic ions hitting a sample and sputter material from the surface of a specimen. The generated secondary ions are separated and detected with high mass resolution to determine the target materials constitution. Based on this principle, we present an alternative approach implementing a compact Electron Beam Ion Source (EBIS) in combination with a Liquid Metal Ion Source (LMIS).
An LMIS can deliver heavy elements which generate high sputter yields on a target surface. More than 90% of this sputtered material consists of mono- and polyatomic neutrals. These particles are able to penetrate the magnetic field of an EBIS and they will be ionized within the electron beam.
A broad spectrum of singly up to highly charged ions can be extracted depending on the operation conditions. Polyatomic ions will decay during the charge-up process. A standard bending magnet or a Wien filter is used to separate the different ion species due to their mass-to-charge ratio. Using different charge states of ions as it is common with EBIS it is also possible to resolve interferring charge-to-mass ratios of only singly charged ions.
Different setups for the realization of feeding the electron beam with sputtered atoms of solids will be presented and discussed. As an example the analysis of a copper surface is used to show high-resolution spectra with low background noise. Individual copper isotopes and clusters with different isotope compositions can be resolved at equal atomic numbers.
These results are a first step for the development of a new compact low-cost and high-resolution mass spectrometry system. In a more general context, the described technique demonstrates an efficient method for feeding an EBIS with atoms of nearly all solid elements from various solid target materials. The new straightforward design of the presented setup should be of high interest for a broad range of applications in materials research as well as for applications connected to analyzing the biosphere, hydrosphere, lithosphere, cosmosphere and technosphere.

Keywords: Electron Beam Ion Source, LMIS, Sputter yield, Mass Spectra
  • Lecture (Conference):
    International Symposium Electron Beam Ion Sources and Traps, EBIST 2014, 18.-21.05.2014, East Lansing, Michigan, USA
Registration No. 20900

Development and characterization of new liquid metal ion sources
Bischoff, L.; Pilz, W.; Tajmar, M.
Abstract: In the last decades liquid metal ion sources (LMIS) working in focused ion beam (FIB) systems became an irrecoverable instrument in research and industry [1]. Sample preparation, local ion implantation and ion analysis are the main application topics. Most of the systems are equipped with a gallium LMIS. But, modern trends in nanotechnology require more extended properties like variable ion species for local doping, non-contaminating milling at higher rates or the application of focused cluster beams for surface modifications [2]. LMIS are also used for space propulsion as precision thrusters to provide ultrastable attitude and orbit control for satellites called Field-Emission- Electric-Propulsion [3].
In this contribution the basics of LMIS operation, the measurement of the main parameters and so the characterization of this type of ion sources will be presented. Moreover, the application of new source concepts including prototypes will be shown. At present about half of the periodic table can be provided as single or double charged ions as well as heavy cluster ions up to five atoms per ion by alloy LMIS. This provokes the interest to apply such sources not only in focused ion beam systems but also in high energy single-end ion accelerators. A first concept for an injector module to adapt a high current LMIS with integrated mass separation to a high energy ion beam system will be presented and discussed.

The authors would like to thank BMBF for financial support under Projekt 05K130DC: "Verbundprojekt 05K2013 – Ioneninduzierte Materialanalyse/-modifizierung: Modifizierung und in-situ Analyse von Materialien durch mittelenergetische Ionenbestrahlung. TP 1: Ultraschwere Ionen und deren Nutzung an HZDR-Beschleunigern."

[1] L. Bischoff, R. Böttger, P. Philipp and B. Schmidt, Nanostructures by mass-separated FIB, Book chapter in “FIB Nanostructures” in “Lecture Notes in Nanoscale Science and Technology” ed. Z. Wang, Peking, Berlin: Springer, 2013, Vol. 20, 465.
[2] L. Bischoff, K.-H. Heinig, B. Schmidt, S. Facsko and W. Pilz, Nucl. Instr. and Meth. B 2012, 272 198.
[3] M. Tajmar, I. Vasiljevich and W. Grienauer, Ultramicroscopy 2010, 111, 1.

Keywords: Liquid metal ion source, cluster, single-end ion accelerators
  • Lecture (Conference):
    Workshop Ionenstrahlen & Nanostrukturen, 20.-22.07.2014, Paderborn, Deutschland
Registration No. 20899

Efficient corrosion protection of organ pipes and turbine blades by Plasma immersion ion implantation.
Pelic, B.; Skorupa, W.; Yankov, R.
Abstract: Experiments have been undertaken to explore the improvement of the high temperature oxidation and aqueous corrosion of Ti-Al and Cu-Zn, respectively, by applying plasma based ion implantation (PBII).
The atmospheric corrosion of the tongues within the reed pipes which consist of a Cu-20Zn alloy (namely brass) is strongly enhanced by traces of acid vapors (from wooden parts and glue) and also the alloy’s instability caused by dezincification. A significant improvement in corrosion resistance has been achieved by applying a 30 nm aluminum oxide film using pulsed laser deposition (PLD) and implanting nitrogen ions into the near surface and the interface regions. In the case of Γ-TiAl alloys which exhibit poor oxidation resistance, despite their good mechanical properties at elevated temperatures, this limits their replacement of the nowadays used heavy components made of Ni-alloys. A significant improvement in high temperature oxidation resistance of TiAl alloys (up to 900 °C) has been achieved by implanting fluorine ions (1017 cm-2) at 30 keV into the alloy’s subsurface using PBII process. A TiAl alloy modified in this way has been shown to acquire a stable, adherent and highly protective alumina scale (Al2O3) under high temperature oxidation in air. The influence of the implanted N+ into CuZn and F+ into TiAl samples on the corrosion process has been investigated. For the sample evaluation, different characterization methods including scanning electron microscope with energy dispersive X-ray spectroscopy (SEM / EDX), Auger electron spectroscopy (AES), Rutherford backscattering spectroscopy (RBS), Elastic recoil detection analysis (ERDA), and Dektak stylus profiling have been applied to determine the chemical composition, the elemental depth profiles, roughness and defect formation of the samples before and after exposure.

Keywords: Plasma based ion implantation (PBII), Pulsed laser deposition (PLD), oxidation protection, Ti-Al alloys, corrosion of reed organ pipes, Cu-Zn alloys
  • Poster:
    IBMM 2014 - 19th International Conference on Ion Beam Modification of Materials, 14.-19.09.2014, Leuven, Belgium
Registration No. 20897

Ultraschwere Ionen und deren Nutzung an HZDR-Beschleunigern.
Tajmar, M.; Pilz, W.; Bischoff, L.
Abstract: Die Modifizierung von Festkörperoberflächen durch energiereiche polyatomare Ionen („Cluster­ionen“) ist ein neues For­schungsgebiet von hohem Interesse. Diese Projektile (mehrere100 atomare Masseeinheiten) deponieren eine extrem hohe Energie­dichte, da zur glei­chen Zeit am gleichen Ort mehrere Atome mit der Fest­körperoberfläche wechselwirken. Dadurch können z.B. Oberflächenmodifikationen durch nano­skaliges Oberflächenschmelzen erreicht aber auch Io­nen­erosion durch thermisch aktiviertes Sputtern untersucht werden. Bisherige aussichtsreiche Untersuchungen wurden an Fokussierten Ionenstrahlsystemen (FIB) mit Flüssigmetall-Ionenquellen (LMIS) durchgeführt, die auf Grund der kleinen Ionenströme nur Strukturen im µm- Bereich zuließen. Um diese Erfahrungen für großflächige Untersuchungen nutzbar zu machen, sind Clusterinjektionssysteme erforderlich, die etwa den 1000fachen Ionenstrom liefern und so für Ionenbeschleuniger mittlerer Energie interessant werden.
Dafür werden nun Flüssigmetallionenquellen, die mit neuartigen porö­sen Emittern arbeiten, eingesetzt (Spin-Off aus der Weltraumforschung zu Ionenantrieben), die unterschiedlichste Metall-Clusterionen (z.B. Bi3 mit über 600 atomaren Masseneinheiten) emittieren können und lange Lebensdauern garantieren. Diese Quellen werden mit einer speziell entwickelten Ionenoptik kombiniert, um einen maximalen Ionenstrom fokussiert bereitzustellen.
Derartige Clusterionen-Injektoren werdend zuerst am 500 kV Ionenbeschleuniger des Ionenstrahlzentrums des HZDR (IBC) in Betrieb genom­men, sind aber nachfolgend auch für andere Singletron-Maschinen oder als Ter­mi­nal­quelle an einem Tandem-Beschleuniger nutzbar.

Keywords: Cluster ions, surface modification, implanter source
  • Lecture (Conference):
    SNI 2014 Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Großgeräten, 21.-23.09.2014, Bonn, Deutschland
Registration No. 20896

Sputter yield of heavy monatomic and polyatomic ions: dependence on impact angle and substrate temperature
Bischoff, L.; Böttger, R.; Facsko, S.; Heinig, K.-H.; Pilz, W.
Abstract: Focussed ion beam irradiation can be used to pattern surfaces at a scale of tens of nm by direct writing as well as by self-organization. Both patterning modes are controlled by ion beam erosion, where the sputter yield depends on the ion species, i.e. their mass, energy and angle of incidence. It depends also on the composition, temperature and surface roughness of the substrate.
Here, peculiarities of sputtering with heavy monatomic and very heavy polyatomic ions will be presented. Ion erosion of Si, SiO2, Ge and GaAs with Au_n and Bi_n ions from a liquid metal ion source has been investigated for different irradiation conditions.
The sputter yield per incoming atom is, compared with monatomic ions, considerably higher for polyatomic ions, even if the kinetic energy per atom is chosen to be equal. A newly developed sample holder allows irradiation at substrates temperatures up to 500°C and angles of ion incidence in the range from 0° to almost 90°, which will be used to elaborate sputter yield data of polyatomic ions in a range not yet explored so far. Due to the extremely high energy density deposition into the collision cascade volume by a very heavy polyatomic ion impact, an almost classical but tiny, transient melt pool can form, which adds to the collisional sputtering a loss of atoms by evaporation [1]. The latter contribution can be increased by substrate heating. Besides of the increased sputter yield, the repeated melting and resolidification of tiny pools leads to well-ordered surface pattern [2], which in turn influence the sputter yield.
[1] C. Anders, K.-H. Heinig and H. Urbassek, Phys. Rev. B 87 (2012) 198.
[2] L. Bischoff, K.-H. Heinig, B. Schmidt, S. Facsko and W. Pilz, Nucl. Instr. Meth. Phys. Res.
B 272 (2012) 198.

Keywords: Sputtering, heavy ions, impact angle, temperature
  • Lecture (Conference):
    19th International Conference on Ion Beam Modification of Materials (IBMM 2014), 14.-19.09.2014, Leuven, Belgien
Registration No. 20895

Microbial leaching of rare earth elements from fluorescent phosphor
Mey, S.; Kutschke, S.; Pollmann, K.
Abstract: Rare Earth Elements (REE) are used in mostly all new technologies and until now, there is no environmentally friendly recycling-process for fluorescent phosphor. Furthermore, China has with a worldwide market share of 94 % (2011) [1] a virtual monopoly in the production of REE. Therefore, there is increasing demand for novel recycling technologies to secure the supply of REE. During recycling of energy-saving bulbs fluorescent phosphor containing rare earth elements (REE) is collected as a distinct fraction. In this study hydrometallurgical techniques were investigated to recycle REE from spent technological products. Due to electrochemical restrictions, leaching with organic acids and metal binding molecules is more promising, than oxidation or reduction reactions [2, 3]. On this basis, different hetero- and autotroph aerobe microorganism pure and mixed cultures are selected. Among them are “classical” leaching organisms like Acidithiobacillus ferrooxidans and A. thiooxidans, as well as the organic acid producing Corynebacterium collunae (glutamic acid), the yeast Yarrowia lipolytica (citric acid) and the tea fungus kombucha. The investigations regarding their ability to leach the REE from fluorescent phosphor, originating from recycling processes, were performed in fed-batch experiments.
It could be shown that complexation of the REE by organic acids produced by the microorganisms lead to considerable higher concentrations of REE in the supernatant than in the control. These results show that the usage of microbial processes for the recovery of REE is possible and could be an eco-friendly alternative to the currently employed methods.

1. Roskill, Rare Earths & Yttrium: Market Outlook to 2015. 14th Edition ed. 2011, London. 534.
2. Evans, C.H., Biochemistry of the Lanthanides. Biochemistry of the Elements, ed. E. Frieden. Vol. 1. 1990, New York, London: Plenum Press. 444.
3. Morss, L.R., Yttrium, Lanthanum, and the Lanthanide Elements, in Standard Potentials in Aqueous Solution, A.J. Bard, R. Parsons, and J. Jordan, Editors. 1985, Marcel Dekker, Ink.: New York, Basel. p. 587-629.

Keywords: Bioleaching Fluorescent Phosphor Recycling Kombucha
  • Lecture (Conference):
    Microbiology and Infection 2014 4. Gemeinsamer Kongress von DGHM und VAAM, 05.-08.10.2014, Dresden, Deutschland
Registration No. 20893

Microbial Leaching of Rare Earth Elements from fluorescent phosphor
Mey, S.; Kutschke, S.; Möckel, R.; Pollmann, K.
Abstract: kein Abstract (war für die Summer School nicht erforderlich)
Keywords: Bioleaching Fluorescent Phosphor Recycling Kombucha
  • Poster:
    EREAN Summer School on Rare Earth Technology, 18.-21.08.2014, Leuven, Belgien
Registration No. 20892

Paramagnetic moments in YBa2Cu3O7-δ nanocomposite films
Dias, F. T.; Vieira, V. N.; Silva, D. L.; Albino Aguiar, J.; Valadao, D. R. B.; Obradors, X.; Puig, T.; Wolff-Fabris, F.; Kampert, E.
Abstract: We report on magnetization studies in YBa2Cu3O7-δ thin films with dispersed Ba2YTaO6 nanoparticles. The magnetization measurements were made using a superconducting quantum interference device (SQUID) and a vibrating sample magnetometer (VSM). Magnetic moments were measured as functions temperature using zero-field cooling (ZFC) and field-cooled (FC) prescriptions for magnetic fields up to 10 T applied parallel and perpendicular to the ab planes. A paramagnetic response related to the superconducting state was observed during the FC experiments. This effect, known as paramagnetic Meissner effect (PME), apparently increases when the magnetic field is increased. We discuss our PME results in terms of the strong pinning scenario modulated by Ba2YTaO6 nanoparticles dispersed into the superconducting matrix. Registration No. 20891

Commissioning of an improved superconducting RF photo injector at ELBE
Teichert, J.; Arnold, A.; Freitag, M.; Lu, P.; Michel, P.; Murcek, P.; Vennekate, H.; Xiang, R.; Kneisel, P.; Will, I.
Abstract: In order to produce high-brightness electron beams in a superconducting RF photo injector, the most important point is to reach a high acceleration field in the cavity. For this reason two new 3.5-cell niobium cavities were fabricated, chemically treated and cleaned in collaboration with Jlab. The first of these two cavities was shipped to HZDR and assembled in new cryomodule. This new gun (SRF Gun II) was installed in the ELBE accelerator hall in May 2014 and replaces the previous SRF Gun I which was in operation since 2007. Beside the new cavity the ELBE SRF gun II differs from the previous gun by the integration of a superconducting solenoid in the cryomodule. After a first test run with a Cu cathode the gun will be operated with normal-conducting Cs2Te photo cathodes.
Keywords: superconducting RF photo enjector, electron source, SRf gun, photo cathode, niobium cavity
  • Poster:
    36th International Free Electron Laser Conference FEL 2014, 25.-29.08.2014, Basel, Schweiz
Registration No. 20890

Inbetriebnahme der SRF-Gun II am ELBE-Beschleuniger
Teichert, J.; Arnold, A.; Lu, P.; Murcek, P.; Vennekate, H.; Xiang, R.; Kamps, T.; Will, I.; Kneisel, P.
Abstract: Hochfrequenz-Photoelektronenquellen mit supraleitenden Resonatoren (SRF-Gun) besitzen das Potential Elektronenstrahlen exzellenter Qualität und mit hohem Strahlstrom zu liefern, die für zukünftige Lichtquellen benötigt werden. An der Strahlungsquelle ELBE ist eine solche Quelle seit 2007 in Betrieb. In den vergangen Jahren wurde eine verbesserte Version (ELBE SRF-Gun II) entwickelt. Im Mai 2014 wurde die SRF-Gun II am Beschleuniger installiert. Das Poster stellt diese Elektronenquelle vor und berichtet über die Inbetriebnahme.
Keywords: electron injector, SRF, superconducting RF accelerator, photo cathode
  • Poster:
    Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Großgeräten 2014, 21.-23.09.2014, Bonn, Germany
Registration No. 20889

Deutsche Forschungskompetenz im europäischen Rahmen im Rohstoffbereich
Köpf, H.; Gutzmer, J.; Klossek, A.
Abstract: Eine der Grundbedingungen für den wirtschaftlichen Erfolg des produzierenden Sektors der Industrie ist die Verfügbarkeit von mineralischen und metallischen Rohstoffen.
Rohstoffe müssen nach den Erfordernissen der Industrie in adäquaten Mengen und zu wirtschaftlich vertretbaren Preisen verfügbar sein. Dies wurde in den letzten Jahren durch Verwerfungen und Preisvolatilitäten auf den globalen Rohstoffmärkten – gefolgt von zum Teil sehr heftigen Reaktionen aus der betroffenen Industrie – eindringlich unterstrichen. Die Versorgung der Industrie mit mineralischen und metallischen Rohstoffen ist vollständig globalisiert, vielstufig und in vielen Fällen für den Endverbraucher intransparent. Dies gilt insbesondere für die Märkte der so genannten Hochtechnologiemetalle, die in der Regel ein sehr geringes globales Volumen erreichen, aber zeitgleich hochspezialisiert und vielgliedrig sind.
Als dicht bevölkerter und hochindustrialisierter Kontinent ist Europa weitgehend abhängig von Rohstoffimporten. Diese Situation wird sich auch in absehbarer Zukunft nicht wesentlich verändern. Insbesondere gilt dies für die Bundesrepublik Deutschland. Als größte europäische Volkswirtschaft hat die Bundesrepublik Deutschland eine stark ausgeprägte industrielle Basis. Dies zieht einen hohen Rohstoffbedarf nach sich, welcher im Falle von Deutschland zusammentrifft mit einer weitgehend erodierten heimischen Metallerzbergbau- und Hüttenindustrie, sowie einer fast vollständig fehlenden Beteiligung deutscher Firmen an der globalen Rohstoffindustrie. Tatsächlich geriet die Forschung und Entwicklung zur Rohstoffversorgung, d.h. der Exploration, der Gewinnung und der Aufbereitung von Rohstoffen, seit Ende der 1980er Jahre zunehmend aus dem wirtschafts- wissenschaftspolitischen Fokus. Dies führte dazu, dass die Forschung und Entwicklung im akademischen Bereich und das Engagement von deutschen Industrieunternehmen in den relevanten Forschungsfeldern nahezu zum Erliegen kam [4].
Auf der anderen Seite hat die Bundesrepublik Deutschland den Anspruch, ein weltweit führender Hochtechnologiestandort zu sein – und verfolgt das Ziel, diese Position zu halten bzw. auszubauen. In der Tat gibt es eine erhebliche Anzahl deutscher Firmen, die in ihren Marktnischen im Anbietermarkt für Technologien zur Rohstoffgewinnung und -verarbeitung (Bergbau, Aufbereitung, Metallurgie, Recycling) Marktführer sind. Dies gilt insbesondere für den Maschinen- und Anlagenbau. Weiterhin gibt es eine kleine Anzahl von Universitäten und außeruniversitären Einrichtungen in Deutschland, die einen signifikanten Beitrag zu Ausbildung und Innovation für die globale Rohstoffindustrie leisten. Nur durch eine geeignete enge Verzahnung der relevanten Kompetenzen in Industrie und Forschung erscheint es möglich, den Beitrag Deutschlands zur effizienten und umweltgerechten Produktion mineralischer und metallischer Rohstoffe rasch signifikant zu erhöhen. Gleichzeitig wird auch eine engere Vernetzung auf europäischer Ebene angestrebt, wobei Deutschland mit seiner hohen Abhängigkeit von Rohstoffimporten auch hier besondere Verantwortung übernehmen muss.
  • Contribution to proceedings:
    Berliner Recycling- und Rohstoffkonferenz, 24.-25.03.2014, Berlin, Germany
    Recycling und Rohstoffe, Berlin: TK Verlag
Registration No. 20887

Morphology analysis of sponge-like Si-SiO2 nanocomposites using energy-filtered electron tomography and electron holographic tomography
Hübner, R.; Wolf, D.; Friedrich, D.; Liedke, B.; Schmidt, B.; Heinig, K.-H.
Abstract: Due to the possibility of band-gap engineering by quantum confinement, Si nanosponge structures embedded in SiO2 formed by spinodal decomposition of metastable silicon-rich silicon oxide are promising absorbers for 3rd generation solar cells. High-temperature annealing of thermodynamically metastable, silicon-rich oxide SiOx with x < 2 leads to phase separation of elemental Si from stoichiometric SiO2. While this phase separation results in disconnected Si nanoclusters for 1.2 ≤ x < 2, percolated Si nanostructures with a sponge-like morphology are observed for x < 1.2 [1].
To visualize the sponge-like morphology in SiOx films for x around 1 after thermal treatment, energy-filtered transmission electron microscopy (EFTEM) imaging, EFTEM tomography, and electron holographic tomography (EHT) [2] were carried out. To this end, 200 nm thick SiOx layers were prepared on p type (100) Si wafers by magnetron sputtering in Ar plasma from two simultaneously operating Si and SiO2 targets. During subsequent annealing, samples were heated up to 1150 °C. Sponge-like nanostructures were investigated by EFTEM imaging using an image-corrected FEI Titan 80-300 microscope equipped with a GIF 863. For EFTEM tomography, a tilt series between ±70° was acquired in a Philips CM200 FEG microscope with a GIF 678, and for EHT, a tilt series from -74° to +79° was recorded in an image-corrected FEI Tecnai TF20 microscope. Tomographic reconstruction of the Si 3D morphology was performed with the Weighted Simultaneous Iterative Reconstruction Technique [3].
Valence-band plasmon energy-loss imaging is an appropriate approach to visualize the Si morphology in phase-separated Si-SiO2 nanocomposites [4]. As an example, Figure 1 shows the Si plasmon EFTEM images (Eloss = 17 eV) of a SiOx≈1 layer decomposed into Si and SiO2 after thermal treatment at 1100 °C for 3 min (left) and 3 h (right). As indicated by the selected area electron diffraction patterns, coarsening of the Si nanostructure is accompanied by Si crystallite growth. Although Si plasmon EFTEM imaging can show the Si phase distribution in a planar projection, it does not provide 3D information. Therefore, EFTEM tomography was applied, revealing that a spinodal sponge-like morphology of Si is only partially visible in a volume of ca. (30 nm)³ (Figure 2). However, in a larger volume of ca. (140 nm)³ - as demonstrated by applying EHT on a needle-shaped specimen prepared by FIB - both isolated nanoparticles and percolated Si nanostructures with a sponge-like morphology are observed (Figure 3).

[1] T. Müller et al., Appl Phys Lett 85 (2004) 12.
[2] D. Wolf et al., Curr Opin Solid St M 17 (2013) 126.
[3] D. Wolf et al., Ultramicroscopy 136 (2014) 15.
[4] D. Friedrich et al., Appl Phys Lett 103 (2013) 131911.

The authors kindly acknowledge TEM sample preparation by Annette Kunz and Martina Missbach.

Keywords: silicon-rich silicon oxide, EFTEM imaging, EFTEM tomography, electron holographic tomography
  • Poster:
    18th International Microscopy Congress, 07.-12.09.2014, Prague, Czech Republic
  • Contribution to proceedings:
    18th International Microscopy Congress, 07.-12.09.2014, Prague, Czech Republic
Registration No. 20883

Biologische Bausteine für Materialien der Zukunft
Kostudis, S.; Weinert, U.; Raff, J.
Abstract: Der Vortrag stellt das Helmholtz-Zentrum Dresden-Rossendorf sowie das Helmholtz-Institut Freiberg für Ressourcentechnologie vor und gibt Einblick in Arbeiten der Arbeitsgruppe Biotechnologie. Mithilfe mikrobiologischer Organismen, Bausteine und Prozesse können neue umweltfreundliche und nachhaltige industrielle Anwendungen wie Filter und Sensoren entwickelt werden.
  • Lecture (others):
    Vortragsreihe "Werte-Wege-Welt", 13.12.2013, Bautzen, Deutschland
Registration No. 20880

Detection of Alteration Induced by Onshore Gas Seeps from ASTER and WorldView-2 Data
Salati, S.; van Ruitenbeek, F.; van der Meer, F.; Naimi, B.
Abstract: Hydrocarbon seeps cause chemical and mineralogical changes at the surface, which can be detected by remote sensing. This paper aims at the detection of mineral alteration induced by gas seeps in a marly limestone formation, SW Iran. For this purpose, the multispectral Advance Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the high spatial resolution WorldView-2 (WV-2) data were utilized for mapping surficial rock alteration. In addition, the potential of Visible Near Infrared (VNIR) bands of the WV-2 and its high spatial resolution for mapping alterations was determined. Band ratioing, principal component analysis (PCA), data fusion and the boosted regression trees (BRT) were applied to enhance and classify the altered and unaltered marly limestone formation. The alteration zones were identified and mapped by remote sensing analyses. Integrating the WV-2 into the ASTER data improved the spatial accuracy of the BRT classifications. The results showed that the BRT classification of the multiple band imagery (created from ASTER and WV-2) using regions of interest (ROIs) around field data provides the best discrimination between altered and unaltered areas. It is suggested that the WV-2 dataset can provide a potential tool along higher spectral resolution data for mapping alteration minerals related to hydrocarbon seeps in arid and semi-arid areas.
Keywords: hydrocarbon seep; alteration mineral; ASTER; WorldView-2; boosted regression trees (BRT) classification Registration No. 20878

Near surface silicide formation after off-normal Fe-implantation of Si(001) surfaces
Khanbabaee, B.; Lützenkirchen-Hecht, D.; Hübner, R.; Grenzer, J.; Facsko, S.; Pietsch, U.
Abstract: We report on formation of non-crystalline Fe-silicides of various stoichiometries below the amorphized surface of crystalline Si(001) after irradiation with 5 keV Fe+ ions under off-normal incidence. We examined samples prepared with ion fluences of 0.1 × 1017 and 5 × 1017 ions cm−2 exhibiting a flat and patterned surface morphology, respectively. Whereas the iron silicides are found across the whole surface of the flat sample, they are concentrated at the top of ridges at the rippled surface. A depth resolved analysis of the chemical states of Si and Fe atoms in the near surface region was performed by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy (XAS) using synchrotron radiation. The chemical shift and the line shape of the Si 2p core levels and valence bands were measured and associated with the formation of silicide bonds of different stoichiometric composition changing from an Fe-rich silicides (Fe3Si) close to the surface into a Si-rich silicide (FeSi2) towards the inner interface to the Si(001) substrate. This finding is supported by XAS analysis at the Fe K-edge which shows changes of the chemical environment and the near order atomic coordination of the Fe atoms in the region close to surface. Because a similar Fe depth profile has been found for samples co-sputtered with Fe during Kr+ ion irradiation, our results suggest the importance of chemically bonded Fe in the surface region for the process of ripple formation. Registration No. 20877

Biologische Bausteine für Materialien der Zukunft
Kostudis, S.; Weinert, U.; Raff, J.
Abstract: Der Vortrag stellt das Helmholtz-Zentrum Dresden-Rossendorf sowie das Helmholtz-Institut Freiberg für Ressourcentechnologie vor und gibt Einblick in Arbeiten der Arbeitsgruppe Biotechnologie. Mithilfe mikrobiologischer Organismen, Bausteine und Prozesse können neue umweltfreundliche und nachhaltige industrielle Anwendungen wie Filter und Sensoren entwickelt werden.
  • Lecture (others):
    Tag der Wissenschaften 2013, 13.06.2013, Radebeul, Deutschland
Registration No. 20876

Bioleaching of copper from Kupferschiefer by organic acid and heterotrophic bacteria
Kostudis, S.; Bachmann, K.; Kutschke, S.; Pollmann, K.
Abstract: Increasing prices of metals and strategic issues such as independent resource access force reconsideration of European Kupferschiefer deposits in Germany. For the mode of exploitation is cost-intensive and the copper content does hardly exceed four percent the processing has to be all the more efficient. This advantage of efficiency as well as ecological friendliness is brought along by biomining – the usage of biological components for metal extraction. For Kupferschiefer (Polkowice, Poland) bears carbonates up to 10 % commonly used bioleaching with acidophilic microorganisms is an issue. Therefore heterotrophic microbes and their metabolites were investigated. Results show copper yields up to nearly 48 % in undirected proof-of-principle batches.
Keywords: sulphide ores, bacteria, bioleaching, liberation analysis, environmental
  • Lecture (Conference):
    Biohydrometallurgy '14, 09.-11.06.2014, Falmouth, United Kingdom
Registration No. 20875

Visualization and quantitative analysis of dispersive mixing by a helical static mixer in upward co-current gas-liquid flow
Rabha, S.; Schubert, M.; Grugel, F.; Banowski, M.; Hampel, U.
Abstract: Growing interest towards process intensification in chemical industries over the last decade promotes static mixers as an attractive contactor alternative to the bubble column and mechanically stirred vessels. In the present work, the dispersion provided by a helical static mixer in a vertical pipe at turbulent gas-liquid flow conditions was studied using ultrafast electron beam X-ray tomography. Dispersive mixing was quantified upstream and downstream of three, six and nine helical static mixer elements in terms of bubble size distribution and gas holdup. Bubble breakup within the mixer elements was visualized and quantified via bubble size distribution and interfacial area density. Moreover, the power dissipation per unit mass of liquid was calculated for different number of static mixer elements and slip. The results provide a new insight into the development of the gas phase distribution within helical static mixers and a sound basis for design improvement, optimization of flow conditions and CFD validation.
Keywords: Helical static mixer, Ultrafast electron beam X-ray tomography, Gas-liquid flows, Specific interfacial area. Registration No. 20874

PGE geochemistry of the Fengshan porphyry–skarn Cu–Mo deposit, Hubei Province, Eastern China
Wang, M.; Gutzmer, J.; Michalak, P. P.; Guo, X.; Xiao, F.; Wang, W.; Liu, K.
Abstract: The Fengshan Cu–Mo deposit is located in the western part of the Jiurui Cu–Au–Mo district in the Late Mesozoic Middle–Lower Yangtze River Metallogenic Belt (YRMB), Eastern China. The mineralization is spatially associated with the Fengshan granodiorite porphyry stock (149–138 Ma), where two types of ore bodies (porphyry, skarn) occur. The Fengshan deposit is located on the Yangtze Craton, i.e., in an intracontinental extensional environment, a geological setting not considered by previous studies of PGE abundance and distribution in porphyry systems. For the present investigation the PGE geochemistry of fourteen samples of the granodiorite, ore and flotation concentrates were determined by ICP-MS, after preconcentration by the Lead Fire Assay technique from large (30 g) samples. A maximum of 32 ppb Pd and 81.2 ppb Pt is reported for the molybdenum flotation concentrate. Cu, Au, Pt, Pd contents from flotation concentrate samples are almost 1 to 2 orders of magnitude higher than those reported for ore samples; this is especially true for the Pt content. Covariant diagrams of Cu and Mo with noble metals (Au, Ag, Pt and Pd) reveal weak correlation between Cu vs. Au, Ag, and Mo vs. Pt. Also, Au shows a slightly positive relationship with Pt and Pd.

It is apparent that Pd and Pt contents of flotation concentrate from the Fengshan deposit are considerably lower than those reported for porphyry deposits in an island arc setting. However, Au and Ag appear to be elevated in the Fengshan deposit. The intrusion derived from an enriched mantle source, high oxygen fugacity (fO2), and liberation of mantle sulfates during partial melting, are the first steps for PGE enrichment in porphyry Cu deposits. However, the Fengshan granodiorite was most likely generated by partial melting of enriched mantle that was previously metasomatized by slab melts related to an ancient subduction system. Au, Pt, and Pd in potassic alteration zones and/or endocontact zones are transported as an aqueous chloride complex in high temperature, hypersaline fluid. In contrast, Au, Pt and Pd would be transported by bisulfide complex in low temperature, intermediate salinity fluid in phyllic alteration zones and/or exocontact marble. That is distinctly different from the porphyry Cu deposits in an island arc environment, where intrusion derived directly from slab melting and Pd and Pt are transported only as chloride complexes.

Keywords: Platinum group elements; Porphyry–skarn Cu–Mo deposit; Fengshan; Eastern China Registration No. 20873

New lithogeochemical and mineralogical exploration of Li-Sn greisen mineralisation in old mining adits of the Zinnwald deposit, Germany
Neßler, J.; Seifert, T.; Gutzmer, J.; Müller, A.; Henker, J.; Kühn, K.
Abstract: The polymetallic Zinnwald-Cínovec deposit is represented by greisen-type mineralisation hosted within the apical portion of a small granite intrusion. Similar to other granitic stocks with Sn-W mineralisation in the Erzgebirge, the Zinnwald granite intruded during the post-collisional stage of the late-Variscan (Permo-Carboniferous) magmatic evolution. These intrusions are characterised by the prominent enrichment of incompatible elements (F, Li, Rb, Cs, Sn, Nb and Ta) and the depletion of P2O5. The deposit is located in the eastern part of the Erzgebirge region, Germany and straddles the border between Germany and the Czech Republic. It is characterised by flat dipping, sheet-like greisen ore bodies (up to 40 m in thickness) and veins (up to 1 m in thickness) located in the apical part and along the quaquaversal dipping edges of the granite stock. The greisen bodies predominantly consist of quartz, Li-Rb-Cs-bearing mica (named zinnwaldite), topaz, fluorite and accessory kaolinite and cassiterite. Historically mined for its cassiterite and wolframite ores since the 16th and 19th century, respectively, the deposit still provides access to a wide spread system of drifts and adits. Selected parts of the underground mine are now presented by the visitor's mine "Vereinigt Zwitterfeld zu Zinnwald". These local conditions are favourable for the re-examination of the exhibited greisen mineralisation. Within the framework of the ongoing Li and Sn exploration project of the SolarWorld Solicium GmbH in the German part of the deposit, an underground sampling campaign has been conducted, incorporating a series of 88 channel samples gained at two different levels (Tiefer Bünau adit = 750 m a.s.l.; Tiefe Hilfe Gottes adit = 720 m a.s.l.). Equally spaced channels of 2 m intervals and approximate dimensions of 180 x 5 x 2.5 cm have been created on pre-selected and detailed mapped walls of two different adits within the mine. The sample material has been gained for mineralogical and geochemical investigation using optical light microscopy and ICP-MS. The herein presented work aims to provide information about the horizontal distribution of selected elements (Li, Rb, Cs, Sn, W, Sc, Nb, Ta and Zn) and to assess historic data on mineralogy and geochemistry. Furthermore, the question of a sufficient sampling distance is tried to answer with the help of statistical exclusion principles. Investigations on the chemical composition of the greisen ore yielded homogeneous concentration of elements contained in micas (Li, Rb, Cs, Zn and Sc!) with Li concentration of about 0.3 wt. %, whereas concentrations of Sn and W (but also Nb and Ta) are more heterogenic distributed with some high-grade values connected to local mica-nests, veins and/or joint planes. Moreover, results of investigated elements from this campaign are in good agreement with the overall geochemical pattern obtained by past investigations. Compared with geochemical whole rock data from drill core samples of surrounding drill holes, the mean Li grades of channel samples are consistent for different areas within the mine. In case of Li, the application of statistical exclusion principles can provide a good estimation of the sufficient maximum sampling distance (about 5 m).
  • Contribution to proceedings:
    EGU General Assembly, 27.04.-02.05.2014, Vienna, Austria
    Geophysical Research Abstracts 16(2014), Vienna: Copernicus
Registration No. 20872

Provenance of the Neoproterozoic rocks of the Gifberg Group (Western South Africa)
van Staden, A.; Zimmermann, U.; Gutzmer, J.; Germs, G. J. B.
Abstract: New petrographic and lithogeochemical data are presented for siliciclastic units of the Gifberg Group (western South Africa), a succession rarely studied in the past. The main detrital source for the oldest succession of the Gifberg Group, the Karoetjes Kop Formation, has been identified as sourced by local metamorphic rocks with a felsic geochemical composition. Nearly unweathered detritus (Chemical index of alteration: 50 to 60; K/Cs >>5000) occurs in the metadiamictite of this formation and is interpreted as palaeovalley infill, deposited only a short distance from its sources. The provenance signature of the overlying Aties Formation indicates significant mafic and/or intermediate sources. Possible sources are rocks of the Bushmanland Group and an unknown unmetamorphosed mafic to intermediate rock succession, which might have been exposed during the deposition of the Aties Formation. The overlying Bloupoort Formation is characterised by a geochemically homogenous metadiamictite (Swartleikrans Bed) with only slightly weathered detritus (K/Cs >10000) and overlying mature silica-rich metarenites and metaconglomerates. It is proposed that the Gifberg basin formed as a small-scale rift basin and then widened through time with subsequent longer sedimentary transport of the detritus which have caused the higher compositional maturity. The predominance of detrital input from local sources in the Karoetjes Kop Formation hinders correlation based on its mineralogical and geochemical content alone. A glacial origin for the Swartleikrans Bed was proposed previously based on the occurrence of possible dropstones. Certain criteria for a glacial depositional environment as outlined by Arnaud and Etienne (2011) were met in our study and include poor sorting, rapid lateral facies changes, crude stratification, variable thicknesses, compositional immaturity, and a gradational contact plus a chaotic texture with large boulders. While these observations point to a ‘rainout’ deposit, there is still a lack of evidence for glacial transport on grain surfaces or in the form of faceted clasts and pebbles. Registration No. 20871

P1309-Magnetooptik mit strukturierten unmagnetischen Metallen
Schmidt, H.; Kaspar, T.; Schmidt, Oliver G.; Brunner, R.
Abstract: Die Erfindung beschreibt die Auslegung einer Anordnung eines regelmäßig strukturierten unmagnetischen Einzel- oder Mehrschichtsystems mit mehreren Basiselementen in der Einheitszellen, bei dem für eine vorgegebene Wellenlänge der einfallenden elektromagnetischen Welle eine bestimmte Polarisation der reflektierten oder transmittierten Welle in Abhängigkeit von einem von außen angelegten Magnetfeld erreicht wird.
  • Patent:
    DE102013203761: Offenlegung-11.09.14; Nachanmeldung WO
Registration No. 20870

Dynamo action driven by a periodically perturbed Beltrami-flow.
Giesecke, A.; Stefani, F.
Abstract: We apply kinematic simulations of the induction equations in order to examine the ability of a Beltrami flow (with curl(V) ~V) generating dynamo action. In the basic state we find a surprisingly complex behavior of the leading azimuthal modes that have a wavenumber up to m=3. Depending on the relation of poloidal to toroidal flow the eigenmodes show slow amplitude modulations and a azimuthal drift of the field pattern.

In a more complex model we add a non-axisymmetric time-dependent flow perturbation. In extension of a previous study we change the (azimuthal) pattern and amplitude of the perturbation flow. Consequently, the magnetic field growth rates are enhanced when the frequency of the perturbation is in the appropriate regime. We find small windows of perturbation frequencies with strong enhancement of the growth rates as well as broader regimes for rather fast drifting perturbations when the perturbation amplitude is sufficient to alter structure of the basic axisymmetric flow.

The effect may be relevant for forthcoming dynamo experiments conducted in Madison or in the precession dynamo experiment at HZDR, where, however, the basic flow will look quite different.

Keywords: Dynamo
  • Lecture (Conference):
    IGDR Annual Meeting Cambridge, 01.-04.09.2014, Cambridge, Great Britain
Registration No. 20865

How to identify groundwater-caused thermal anomalies in lakes based on multi-temporal satellite data in semi-arid regions
Mallast, U.; Gloaguen, R.; Friesen, J.; Roediger, T.; Geyer, S.; Merz, R.; Siebert, C.
Abstract: The deduction by conventional means of qualitative and quantitative information about groundwater discharge into lakes is complicated.
Nevertheless, at least for semi-arid regions with limited surface water availability, this information is crucial to ensure future water availability for drinking and irrigation purposes.
Overcoming this lack of discharge information, we present a satellite-based multi-temporal sea-surface-temperature (SST) approach.
It exploits the occurrence of thermal anomalies to outline groundwater discharge locations using the example of the Dead Sea. Based on a set of 19 Landsat Enhanced Thematic Mapper (ETM+) images 6.2 (high gain), recorded between 2000 and 2002, we developed a novel approach which includes (i) an objective exclusion of surface-runoff-influenced data which would otherwise lead to erroneous results and (ii) a temporal SST variability analysis based on six statistical measures amplifying thermal anomalies caused by groundwater.
After excluding data influenced by surface runoff, we concluded that spatial anomaly patterns of the standard deviation and range of the SST data series spatially fit best to in situ observed discharge locations and, hence, are most suitable for detecting groundwater discharge sites.
Registration No. 20864

Sulfur sources of sedimentary "buckshot" pyrite in the Auriferous Conglomerates of the Mesoarchean Witwatersrand and Ventersdorp Supergroups, Kaapvaal Craton, South Africa
Guy, B. M.; Ono, S.; Gutzmer, J.; Lin, Y.; Beukes, N. J.
Abstract: Large rounded pyrite grains (> 1 mm), commonly referred to as "buckshot" pyrite grains, are a characteristic feature of the auriferous conglomerates (reefs) in the Witwatersrand and Ventersdorp supergroups, Kaapvaal Craton, South Africa. Detailed petrographic analyses of the reefs indicated that the vast majority of the buckshot pyrite grains are of reworked sedimentary origin, i.e., that the pyrite grains originally formed in the sedimentary environment during sedimentation and diagenesis. Forty-one of these reworked sedimentary pyrite grains from the Main, Vaal, Basal, Kalkoenkrans, Beatrix, and Ventersdorp Contact reefs were analyzed for their multiple sulfur isotope compositions (delta S-34, Delta S-33, and Delta S-36) to determine the source of the pyrite sulfur. In addition, five epigenetic pyrite samples (pyrite formed after sedimentation and lithification) from the Middelvlei and the Ventersdorp Contact reefs were measured for comparison. The delta S-34, Delta S-33, and Delta S-36 values of all 41 reworked sedimentary pyrite grains indicate clear signatures of mass-dependent and mass-independent fractionation and range from -6.8 to +13.8 aEuro degrees, -1.7 to +1.7 aEuro degrees, and -3.9 to +0.9 aEuro degrees, respectively. In contrast, the five epigenetic pyrite samples display a very limited range of delta S-34, Delta S-33, and Delta S-36 values (+0.7 to +4.0 aEuro degrees, -0.3 to +0.0 aEuro degrees. and -0.3 to +0.1 aEuro degrees, respectively). Despite the clear signatures of mass-independent sulfur isotope fractionation, very few data points plot along the primary Archean photochemical array suggesting a weak photolytic control over the data set. Instead, other factors command a greater degree of influence such as pyrite paragenesis, the prevailing depositional environment, and non-photolytic sulfur sources. In relation to pyrite paragenesis, reworked syngenetic sedimentary pyrite grains (pyrite originally precipitated along the sediment-water interface) are characterized by negative delta S-34 and Delta S-33 values, suggesting open system conditions with respect to sulfate supply and the presence of microbial sulfate reducers. On the contrary, most reworked diagenetic sedimentary pyrite grains (pyrite originally precipitated below the sediment-water interface) show positive delta S-34 and negative Delta S-33 values, suggesting closed system conditions. Negligible Delta S-33 anomalies from epigenetic pyrite suggest that the sulfur was sourced from a mass-dependent or isotopically homogenous metamorphic/hydrothermal fluid. Contrasting sulfur isotope compositions were also observed from different depositional environments, namely fluvial conglomerates and marine-modified fluvial conglomerates. The bulk of the pyrite grains from fluvial conglomerates are characterized by a wide range of delta S-34 values (-6.2 to +4.8 aEuro degrees) and small Delta S-33 values (+/- 0.3 aEuro degrees). This signature likely represents a crustal sulfate reservoir derived from either volcanic degassing or from weathering of sulfide minerals in the hinterland.
Reworked sedimentary pyrite grains from marine-modified fluvial conglomerates share similar isotope compositions, but also produce a positive Delta S-33/delta S-34 array that overlaps with the composition of Archean barite, suggesting the introduction of marine sulfur.
These results demonstrate the presence of multiple sources of sulfur, which include atmospheric, crustal, and marine reservoirs. The prevalence of the mass-dependent crustal sulfur isotope signature in fluvial conglomerates suggests that sulfate concentrations were probably much higher in terrestrial settings in comparison to marine environments, which were sulfate-deficient. However, the optimum conditions for forming terrestrial sedimentary pyrite were probably not during fluvial progradation but rather during the early phases of flooding of low angle unconformities, i.e., during retrogradational fluvial deposition, coupled in some cases with marine transgressions, immediately following inflection points of maximum rate of relative sea level fall.
Registration No. 20863

P1308-Anordnung zur Bestimmung der Phasenverteilung in mehrphasigen Medien mit mindestens einer hochleitfähigen Phase
Schleicher, E.; Löschau, M.; van Campen, L.
Abstract: Die Erfindung betrifft einen Gittersensor zur Messung der Phasenverteilung eines mehrphasigen Stoffgemisches mit gasförmigen und flüssigen Komponenten unter Vorhandensein einer hochleitfähigen Phase (wie Salzwasser oder Flüssigmetall). Anwendungsgebiete sind die Bestimmung der Flüssigkeitsverteilung und des Füllstands in Gefäßen sowie die Untersuchung von Gas-Flüssigkeits-Mehrphasenströmungen, insbesondere in Rohrleitungen z. B. in der Erdölproduktion und -verarbeitung.
  • Patent:
    DE102013203437.7 - Offenlegung-28.08.2014; Nachanmeldung: WO
Registration No. 20862

Redirection of CD4+ and CD8+ T lymphocytes via a novel antibody-based modular targeting system triggers efficient killing of PSCA+ prostate tumor cells
Arndt, C.; Feldmann, A.; Töpfer, K.; Koristka, S.; Cartellieri, M.; Temme, A.; Ehninger, A.; Ehninger, G.; Bachmann, M.
There is still a need for new therapeutic options against prostate cancer. Conventional single-chain bispecific antibodies (bsAbs), that directly cross-link T cells and tumor cells, hold great potential for efficient tumor treatment. However, rapid development of novel bsAbs is hampered by laborious optimization to improve their efficacy and reduce potential side effects. To accelerate the development of a novel antibody tool for the redirection of T cells to different tumor-associated antigens, we recently introduced a modular targeting system.
We here describe a novel modular system for treatment of prostate cancer by retargeting of T cells to the prostate stem cell antigen (PSCA). Functionality of the novel PSCA-specific modular system was investigated in vitro by T cell activation and chromium release assays as well as in immunodeficient mice.
Similar to a conventional bsAb CD3-PSCA, the novel PSCA-specific modular system induces activation of both CD4+ and CD8+ T cells leading to secretion of pro-inflammatory cytokines and highly efficient target-specific tumor cell lysis. The novel TM was ready-to-use from the time point of construction and functional at low E:T ratios and picomolar concentrations without further optimization. In addition, the PSCA-specific modular system delays outgrowth of s.c. tumors in mice comparable to bsAb CD3-PSCA.
We have developed a novel PSCA-specific modular system which triggers an efficient T cell-mediated killing of PSCA+ tumor cells in vitro and in vivo. The new Ab-based targeting strategy can functionally replace conventional bsAbs and allows a flexible redirection of T cells to different tumor-associated antigens.
Registration No. 20861

Ion-surface interaction in plasma processing
Möller, W.
Abstract: Whereas the studies of ion-surface interaction have been a significant issue in nuclear fusion research through about four decades, corresponding knowledge in the area of low-pressure plasma processing can still be considered as marginal. Qualitatively, it is well accepted that energetic ion bombardment is essential for several processes of plasma surface treatment or plasma-assisted deposition of thin films. For the latter, it plays an important role in determining the growing thin film structure and stoichiometry. However, more quantitative models are only available for a few selected processes and for specific materials.
The lecture will briefly review the state of knowledge. It will particularly focus on the process physics of non-reactive and reactive sputtering. Open questions will be addressed in connection with recent experimental findings and computer simulation results, such as describing self-organized topographical and stoichiometric pattern formation under ion bombardment, and the characteristics of sputtering from such modified surfaces.

Keywords: Ion-surface interaction Hard coatings Magnetron sputtering Plasma processing
  • Invited lecture (Conferences):
    PSE 2014 - International Conference on Plasma Surface Engineering, 15.-20.09.2014, Garmisch-Partenkirchen, Deutschland
Registration No. 20860

Sputtering of nanospheres - a computer simulation study
Möller, W.; Nietiadi, Maureen L.; Urbassek, Herbert M.; Sandoval, L.
Abstract: The sputtering of spherical objects – such as clusters, nanoparticles or aerosol particles – being exposed to energetic ion irradiation has been studied using both Monte Carlo simulation in the binary collisions approximation (MC) and molecular dynamics simulation (MD). 20 keV Ar impact on a-Si has been chosen as a typical example. With a denoting the mean depth of energy deposition in a planar target, inverse scaled cluster radii a/R ranging from 0 to 20 have been investigated, both addressing the impact parameter dependence and the average sputtering yield. For large radii (a/R < 0.2) sphere sputtering follows closely the sputtering of planar targets, if the variation of the incidence angle on the sphere surface is taken into account. For smaller radii, the yield increases due to the influence of sphere curvature. For a/R > 1, pronounced forward sputtering leads to a maximum in the sputter yield. In the limit of small radii, sputter emission becomes largely isotropic, but decreases in yield since the projectile energy is only partly deposited in the sphere and the surface area shrinks. However, for all spheres studied, the average sputter yield is larger than for the planar surface. Within the uncertainties of the modelling, there is an excellent agreement between the planar surface sputtering yields as obtained by MC and MD. For small spheres, however, the MD yields are significantly larger which is attributed to the influence of collisional spikes.
Keywords: Sputtering Nanostructures Computer Simulation
  • Lecture (Conference):
    IBMM 2014 - International Conference on Ion Beam Modification of Materials, 15.-19.09.2014, Leuven, Belgien
Registration No. 20859

Ion beam synthesis of InAs, InGaAs and GaAs nanocrystals in Silicon
Rebohle, L.; Wutzler, R.; Prucnal, S.; Hübner, R.; Grenzer, J.; Helm, M.; Skorupa, W.
Abstract: InAs, InGaAs and GaAs nanocrystals (NCs) were fabricated by sequential ion implantation and flash lamp annealing. In detail, silicon-SiO2-silicon structures were provided with a SiO2 capping layer followed by the sequential implantation of In, Ga and As ions with fluences in the range of a few 1016 at./cm2. In the following step of flash lamp annealing the NCs will be formed in the Si device layer by liquid phase epitaxy. The resulting III-V NCs are mostly single-crystalline with sizes in the range of a few to a few tens of nm. Depending on the specific segregation coefficients and melting temperatures, elemental In clusters can be also formed. The proposed qualitative model for the NC formation is based on Transmission electron microscopy (TEM), Raman spectroscopy, and X-ray diffraction (XRD) measurements.
Keywords: InAs, InGaAs and GaAs nanocrystals, ion implantation, flash lamp annealing, III-V integration into silicon
  • Poster:
    EMRS Fall Meeting 2014, 15.-18.09.2014, Warschau, Polen
Registration No. 20858

Sputtering of Si nanospheres
Nietiadi, M. L.; Sandoval, L.; Urbassek, Herbert M.; Möller, W.
Abstract: Spherical objects, such as clusters, nanoparticles, or aerosol particles, are sputtered when exposed to energetic irradiation.We use Monte Carlo (MC) and molecular dynamics (MD) computer simulation to study this process, with 20 keV Ar impact on a-Si clusters as a prototypical example. The sputter yield is quantified as being influenced by oblique incidence and target curvature. Cluster radii R are scaled to the energy deposition depth, a. For large R (R/a > 5) sphere sputtering follows closely the sputtering of planar targets, if the variation of the incidence angle on the sphere surface is taken into account. For smaller radii, the yield increases due to the influence of curvature. For radii R/a  1 pronounced forward sputtering leads to a maximum in the sputter yield. For smaller R, sputter emission becomes isotropic, but decreases in magnitude since not all the projectile energy is deposited in the sphere. However, for all spheres studied (R > 0.05a) the average sputter yield is larger than for infinitely large spheres (R→∞). A simple model based on linear collision cascade theory and assuming that the energy deposition profile is independent of the sphere size predicts sputtering for large spheres well, but fails for small spheres where it strongly underestimates sputtering. The MC data for the smaller spheres are supplemented by MD calculations, which indicate a significant additional contribution caused by spike sputtering.
Keywords: Sputtering Nanostructures Computer Simulation Binary Collision Approximation Molecular Dynamics Registration No. 20857

The electroluminescence mechanism of Er3+ in different silicon oxide and silicon nitride environments
Rebohle, L.; Berencén, Y.; Wutzler, R.; Braun, M.; Hiller, D.; Ramírez, J. M.; Garrido, B.; Skorupa, M. Helm W.
Abstract: Rare earth doped metal-oxide-semiconductor (MOS) structures are of great interest for Si-based light emission. However, several physical limitations make it difficult to achieve the performance of light emitters based on compound semiconductors. To address this point, in this work the electroluminescence (EL) excitation and quenching mechanism of Er-implanted MOS structures with different designs of the dielectric stack are investigated. The devices usually consist of an injection layer made of SiO2 and an Er-implanted layer made of SiO2, Si-rich SiO2, silicon nitride or Si-rich silicon nitride. All structures implanted with Er show intense EL around 1540 nm with EL power efficiencies in the order of 2×10-3 (for SiO2:Er) or 2×10-4 (all other matrices) for lower current densities. The EL is excited by the impact of hot electrons with an excitation cross section in the range of 0.5-1.5×10-15 cm-2. Whereas the fraction of potentially excitable Er ions in SiO2 can reach values up to 50%, five times lower values were observed for other matrices. The decrease of the EL decay time for devices with Si-rich SiO2 or Si nitride compared to SiO2 as host matrix implies an increase of the number of defects adding additional non-radiative de-excitation paths for Er3+. For all investigated devices EL quenching cross sections in the 10-20 cm2 range and charge-to-breakdown values in the range of 1-10 Ccm-2 were measured. For the present design with a SiO2 acceleration layer, thickness reduction and the use of different host matrices did not improve the EL power efficiency or the operation lifetime, but strongly lowered the operation voltage needed to achieve intense EL.
Keywords: electroluminescence, ion implantation, erbium, MOS structure, decay time Registration No. 20856

Electromagnetic fields of a vertical magnetic dipole above and within a horizontal stratified earth in due consideration of the electrical permittivity
Scheunert, M.; Börner, R.-U.; Siemon, B.
Abstract: Our poster is motivated by the helicopter electromagnetic forward and inversion problem. In this context, we use the secondary field approach to evaluate the total electromagnetic fields of a vertical magnetic dipole (VMD) by a numerical discretization scheme. This approach requires the calculation of an analytic solution of the primary field at every receiver position, located within the air half-space. Furthermore, in order to calculate the Jacobian matrix using the sensitivity equation approach, these primary fields have to be calculated at every degree of freedom within the stratified media. The primary fields are the solution of the Helmholtz equation for a 1-D conductivity distribution.
We show the complete derivation of the electromagnetic fields of a VMD for the magnetic vector potential based on the spatial Hankel transformation. To avoid inaccuracies at high frequencies, varying electrical permittivities are incorporated. We furthermore explain the recursion algorithm that is used to find general expressions at arbitrary depths and which allows us to easily derive the different electromagnetic field components. The calculations start with the simple two layer case and are subsequently expanded to the more general N-layer case. Special attention is payed to a singularity problem arising at the derivation of the horizontal electrical and vertical magnetic fields in the air layer which is resolved by an integration by parts approach.

Keywords: fields of a VMD, stratified earth, HEM, vector potential, Fourier transform
  • Poster:
    22nd EM Induction Workshop, 24.-30.08.2014, Weimar, Deutschland
Registration No. 20855

A Concept for 3-D Inversion of Helicopter Electromagnetic Data Using a Tensor-based Problem Formulation
Scheunert, M.; Afanasjew, M.; Börner, R.-U.; Eiermann, M.; Ernst, O. G.; Spitzer, K.
Abstract: Helicopter electromagnetic (HEM) measurements allow to manage huge surveys in a very short time. Due to the enormous data and model sizes, laterally constrained 1-D inversion schemes for the entire survey are still state of the art, even for those parts of the survey where 3-D conductivity anomalies are expected.

We introduce a new strategy that is based on the precedent localization of the entire HEM survey to parts which are actually affected by an expected local 3-D anomalies. A full 3-D inversion scheme capable of revealing those anomalous conductivity structures is presented that directly benefits from a-priori information, resulting from the localization procedure. We therefore reformulate the discrete forward problem in terms of the secondary electric field, employing either finite difference or finite element methods. For solving the inverse problem, we apply a straightforward Gauss-Newton method and a Tikhonov-type regularization scheme. The concept allows us to additionally restrict the domain where the inverse problem is solved, acting as an implicit regularization. The derived linear least squares problem is solved with Krylov subspace methods, such as LSQR, that are able to deal with the inherent ill-conditioning. The resulting systems of linear equations subsequently yield expressions for the gradient and approximate Hessian of the minimization problem. Resulting from the unique transmitter-receiver relation of the HEM problem, an explicit representation of the Jacobian matrix is used. We further introduce a tensor-based problem formulation that provides a fast update of the linear system of the forward problem and an effective handling of the sensitivity related algebraic quantities, respectively.

Keywords: HEM, 3-D inversion, cut-&-paste strategy, field data, explicit Jacobian
  • Poster:
    74. Jahrestagung der Deutschen Geophysikalischen Gesellschaft (DGG), 10.-13.03.2014, Karlsruhe, Deutschland
Registration No. 20854

EM fields of a VMD calculated at arbitrary points within a layered half-space
Scheunert, M.; Börner, R.-U.; Siemon, B.
Abstract: In this paper, we derive expressions for all electromagnetic (EM) field components which can be observed, when a vertical magnetic dipole (VMD) is located at z = −h, h > 0 over a stratified earth, i.e., when the electrical conductivity is a piecewise constant function of depth z. We further allow a non-vanishing but small electrical conductivity in the air layer, and let the electrical permittivity vary from its vacuum value. Apart from traditional approaches, we use a non-vanishing air conductivity to be consistent with our 3-D discretizations which would otherwise yield singular mass matrices. The basic ideas of the derivation within the following paragraphs emanate from Ward and Hohmann (1988) and Zhdanov (2009). While the first sections of this paper concern the two-layer (i.e., the nearly non-conductive air and the conductive homogeneous half-space) case we expand the concept to the general N-layer case in the last section. This work has been motivated by the one-dimensional forward and inverse problem of helicopter electromagnetics (HEM). To evaluate the observed total fields by a numerical discretization scheme, the secondary field approach requires the calculation of the analytical solution of the EM fields at the receiver positions within the air half-space. Furthermore, in order to calculate the Jacobian matrix, these fields are required at arbitrary points within the conductive layered half-space.
Keywords: electromagnetic fields, vertical magnetic dipole, stratified earth, magnetic vector potential, Fourier transform
  • Contribution to proceedings:
    25. Schmucker-Weidelt-Kolloquium für Elektromagnetische Tiefenforschung, 23.-27.09.2013, Kirchhundem-Rahrbach, Deutschland
    Protokoll über das 25. Schmucker-Weidelt-Kolloquium für Elektromagnetische Tiefenforschung : Kirchhundem-Rahrbach 23.-27. September 2013, Potsdam: Deutsche Geophysikalische Gesellschaft e. V., 5-20
Schmucker-Weidelt-Kolloquium 2013 PDF
Registration No. 20853

Hyperspectral remote sensing of carbonatite hosted REE deposits in Namibia
Zimmermann, R.; Salati, S.; Andreani, L.; Brandmeier, M.; Gloaguen, R.
Abstract: High spectral and spatial resolution of hyperspectral images allow mapping and determination of minerals on the earth surface. It also provide valuable information about ore deposits and their alteration zoning.
Carbonatites are well known for hosting economic concentrations of REE-bearing minerals like bastnäsite, monazite and apatite among others (WINTER 2001). They show signifcant spectral characteristics, even REE-absorption bands (ROWAN et al. 1986).
The aim of our study is to apply recent advances in hyperspectral imaging and to develop new tools in order to map these rocks. A refnement of the geological map by lithological mapping, image classifcation, mineral mapping and tectonic geomorphology is also done.
Our research mainly focuses on carbonatites from Namibia. We selected two sites with well known occurrences in Northern Namibia: the Epembe and the Lofdal dykes. Both yield signifcant REE- concentrations and being under exploration. In these areas LANDSAT 8, SRTM, EO-1 Hyperion and airborne hyperspectral (HyMap) data overlap giving an excellent coverage.
The data had been processed for atmospherical and geometric corrections frst. For the EO-1 Hyperion data a more carefully pre-processing had to be applied due to streaking and smiling effects. Results of LANDSAT 8 classifcation had been used for validation and classifcation purposes. Detailed spectral signatures and mineral maps are extracted by hyperspectral imaging. The results confrm former observations by BEDINI (2009) on the Sarfartoq carbonatite complex in West Greenland. Secondly the structural controls of emplacement of the selected carbonatite dykes had been carried out using tectonic geomorphology and feld observation. For this purpose the TecDEM-toolbox (SHAHZAD & GLOAGUEN 2011) was applied to the SRTM-data for drainage- network and stream-profle analysis.
Combining all these information with geological knowledge of carbonatites and their occurrences, it is possible to explore new, unknown deposits by remote sensing applications.
  • Poster:
    GeoFrankfurt 2014, 22.-24.09.2014, Frankfurt/Main, Deutschland
Registration No. 20851

Cockade breccia: Product of mineralisation along dilational faults
Frenzel, M.; Woodcock, N. H.
Abstract: Cockade breccias are fault fills in which individual clasts are completely surrounded by concentric layers of cement. They occur particularly in low-temperature near-surface hydrothermal veins. At least six mechanisms have been proposed for the formation of cockade breccia-like textures, but only two – repeated rotation-accretion, and partial metasomatic replacement of clast minerals – have been supported by detailed evidence. A typical example of cockade breccia from the Gower Peninsula (South Wales) shows clear evidence for the rotation-accretion mechanism: in particular, overgrown breakage points in cement layers – where cockades were previously touching each other – and rotated geopetal infills of haematitic sediment. Based on the available evidence, it is proposed that cockade textures result from low rates of cement growth compared to high rates of dilational fault slip. Seven criteria are given for the correct identification of cockade breccias.
Keywords: cockade ore; ring ore; syntectonic mineralisation; dilational faulting; epithermal veins Registration No. 20850

Recent results from the high magnetic field laboratory Dresden: Probing the 1D or 2D nature of M2+Ta2O6 (M2+=Ni,Co)
Law, J. M.
Abstract: es hat kein Abstract vorgelegen
  • Invited lecture (Conferences):
    Moscow International Symposium on Magnetism MISM-2014, 29.06.-03.07.2014, Moscow, Russia
Registration No. 20844

ESR Studies of the Spin-1/2 Heisenberg Antiferromagnet Copper Pyrazine Dinitrate
Ozerov, M.
Abstract: Copper pyrazine dinitrate, Cu(C4H4N2)(NO3), is one of the best known model spin-1/2 Heisenberg antiferromagnet chain system. Here, we present electron spin resonance (ESR) studies of this material. Angular, temperature and field dependences of ESR parameters are studied. We evidence the inequivalence of Cu sites belonging to adjacent spin chains in the ac planes. It is revealed that the dominating interchain interaction in this compound is of zig-zag-type. This interaction gives rise to geometrical frustration strongly affecting the character of antiferromagnetic ordering. Combining our experimental findings with the results of a quasiclassical approach we predict that at low temperatures the system orders in an incommensurate spiral state.
  • Poster:
    International Conference on Strongly Correlated Electron Systems, 07.-11.07.2014, Grenoble, France
Registration No. 20843

A 3D microstructural model of freckle initiation from pre-existing imperfections
Karagadde, S.; Yuan, L.; Shevchenko, N.; Eckert, S.; Lee, P. D.
Abstract: The quality and lifing of high performance turbine blades are severely hampered by presence of freckles, which are initiated by presence of enriched solute plumes during solidification [1]. Nickel based turbine blades can be cast as equiaxed, directionally solidified or single crystals. Several types of perturbations may occur during these casting techniques, which can eventually lead to freckles.
In this work, a 3D microstructural numerical model of freckle formation is presented [2]. A typical simulation of stabilized solute plume formation leading to a freckle channel is shown in Fig. 1. The model is validated with in situ x-ray radiographic measurements [3], comparing solute partitioning, convection and freckle channel width. This model was then used to investigate freckle formation under a range of solidification conditions. Using the dendrite tip growth and solute profiles, freckle onset was observed to occur in two distinct stages. The influence of imperfections that occur in primary arm spacing and grain boundary was investigated from the proposed model. It was found that the freckles initiate from these irregularities, with a higher propensity for converging grain boundaries. In addition, the effect of dendrite orientation angle on freckle formation is studied.

Keywords: 3D microstructural model, freckle, x-ray radiography, model validation, dendrite tip growth
  • Lecture (Conference):
    4th International Conference on Advances in Solidification Processes, 08.-11.07.2014, Old Windsor, United Kingdom
Registration No. 20841

Melt flow and temperature gradient effects on freckle formation
Shevchenko, N.; Roshchupkina, O.; Eckert, S.
Abstract: A visualization of the segregation freckle formation and the main convection pattern in solidifying Ga - In alloys was obtained by using the X-ray imaging technique [1, 2]. A Ga - In alloy was used because its density variation and thermo-physical properties are similar to many commercial alloys. Furthermore, it has a very good X-ray contrast and shows a melting point near room temperature. Recently, formation of stable chimney at several solidification conditions and captured the solute distribution and flow velocities were reported [2]. Variations of the vertical and lateral temperature gradients induce modifications of the melt flow pattern, which lead to different segregation structures.
In the case of solidification at higher vertical temperature gradients (up to 2 K/mm), we identified a converging flow ahead of the mushy zone coming from the side walls. Such flow patterns are driven by the lateral temperature gradient and the convex shape of the solidification front. This leads to a continuous accumulation of solute in the central part of the solidification cell followed by a remelting of the solid fraction and the occurrence of a sustaining chimney. This mechanism of chimney formation is different as compared to the case where the evolution of the segregation channel is related to any initial growth defect.
Variations of the lateral temperature gradient by additional side cooling lead to a collapse of the double-vortex convection over entire cell volume. A more complicated flow pattern occurs consisting of multiple convection rolls along the solid - liquid interface. At such solidification conditions a sustainable development of stable chimneys was rarely observed.

Keywords: Visualization, X-ray radioscopy, freckle formation, solid - liquid interface, flow patterns, temperature gradient
  • Lecture (Conference):
    4th International Conference on Advances in Solidification Processes, 08.-11.07.2014, Old Windsor, United Kingdom
Registration No. 20840

In situ X-ray radiography study on the impact of forced melt convection on solidification processes
Shevchenko, N.; Roshchupkina, O.; Eckert, S.
Abstract: In this paper, we present experimental investigations focusing on the question how natural and forced convection influence the microstructure formation in solidifying alloys.
In situ visualization of the solidification of Ga–25wt%In alloys was carried out by means of X-ray radioscopy. An electromagnetically driven flow was produced inside the solidifying liquid by a rotating wheel with two parallel disks containing at their inner sides a set of permanent NdFeB magnets with alternating polarisation [1, 2]. Rotation speeds of the magnetic wheel were chosen in the range of 10 – 80 revolutions per minute resulting in local flow velocities between 0.5 and 1.5 mm/s in the area just ahead of the solidification front. The melt flow is almost perpendicular with respect to the growth direction of the dendrites.
The forced convection induces a redistribution of solute concentration, re-orientation of the dendritic structure, changes of primary and secondary branching, and leads to a formation of segregation channels. Flow patterns, dendrite morphologies and tip velocities were quantified by image analysis and related to the experimental conditions. In principle, the forced flow is an external operational parameter that can be used to control the final microstructure. However, the optimization of the microstructure by electromagnetic flow control is a complex task which requires a deep understanding of the complex interplay between melt flow and solidification process.

Keywords: X-ray radiography, Solidification, Ga-In alloy, Forced convection, Dendritic structure, Tip velocity
  • Lecture (Conference):
    4th International Conference on Advances in Solidification Processes, 08.-11.07.2014, Old Windsor, United Kingdom
Registration No. 20839

Dependence of all-optical magnetic switching on the sublattice magnetization orientation in Tb-Fe thin films
Hassdenteufel, A.; Schubert, C.; Schmidt, J.; Richter, P.; Zahn, D. R. T.; Salvan, G.; Helm, M.; Bratschitsch, R.; Albrecht, M.
Abstract: We demonstrate that the direction of all-optical switching (AOS) in rare-earth transition-metal (RE-TM) alloy Tb-Fe thin films depends on the orientation of the sublattice magnetization and not on the direction of the resulting net magnetization. For this purpose, we investigated the AOS ability for a sample dominated by the Fe sublattice magnetization (Tb24Fe76) and another dominated by the Tb sublattice (Tb30Fe70). This finding of the sublattice dependence of AOS contributes to the understanding of switching in RE-TM multilayered thin films and heterostructures.
Keywords: all-optical magnetic switching, AOS, sublattice magnetization, rare earth metal alloy, Registration No. 20838

Why Do Strategic Alliances Persist? A Behavioral Decision Model
Klossek, A.; Meyer, K. E.; Nippa, M.
Abstract: Strategic alliances are considered a flexible form of organizing, yet they are often long-lived. Even when systematic benefit–cost analysis suggests that their organizational form should be changed or terminated, some alliances still persist. Drawing on behavioral decision theory, we propose a theoretical model that explains this phenomenon. Decision makers are subject to a variety of biases that can lead to the overvaluation of the net benefits of an alliance and, hence, inhibit the change or discontinuation of underperforming alliances. Our model illustrates how decision-making biases at the individual, interpersonal, organizational, and interorganizational levels are moderated by the design of an alliance and the tools employed in the decision-making process. This behavioral decision perspective advances our theoretical understanding of the longevity of strategic alliances and their embeddedness in complex decision-making contexts. Registration No. 20837

High-magnetic-field properties of frustrated magnets
Wosnitza, J.
Abstract: es hat kein Abstract vorgelegen
  • Invited lecture (Conferences):
    13th Japanese-German Symposium “Interplay of Spin- and Orbital Degrees of Freedom in Strongly Correlated Electron Systems”, 13.-16.07.2014, Rottach-Egern, Deutschland
Registration No. 20834

Emerging evidence for FFLO states in layered organic superconductors
Wosnitza, J.
Abstract: es hat kein Abstract vorgelegen
  • Invited lecture (Conferences):
    2nd International Symposium of the SFB/TR 49 on “Novel states in correlated condensed matter – from model systems to real materials”, 08.-10.04.2014, Königstein, Deutschland
Registration No. 20833

The Fulde-Ferrell-Larkin-Ovchinnikov state in layered organic superconductors
Wosnitza, J.
Abstract: es hat kein Abstract vorgelegen
  • Invited lecture (Conferences):
    International Workshop on Topological quantum matter and two-dimensional superconductors, 11.-14.01.2014, Kuming, China
Registration No. 20832

Spin-lattice effects in selected magnetic materials
Zherlitsyn, S.
  • Invited lecture (Conferences):
    V International Conference of Young Scientists LOW TEMPERATURE PHYSICS (ICYS–LTP–2014), 02.-06.06.2014, Kharkov, Ukraine
Registration No. 20828

Direct determination of exchange parameters in spin-1/2 Heisenberg triangular-lattice antiferromagnets: high-field ESR studies
Zvyagin, S.
Abstract: Spin-1/2 Heisenberg antiferromagnets Cs2CuCl4 and Cs2CuBr4 with distorted triangular-lattice structures are studied by means of electron spin resonance spectroscopy in magnetic fields up to the saturation field and above. In the magnetically saturated spin polarized phase, quantum fluctuations are fully suppressed, and the spin dynamics is defined by ordinary magnons. This allows us to accurately describe the magnetic excitation spectra in both materials and, using the harmonic spin-wave theory, to determine their exchange parameters. The proposed approach has a broader impact and can be potentially used for any quantum magnet with reduced (e.g., by the staggered DM interaction) translational symmetry, resulting, as predicted, in emergence of a new exchange mode in the magnetically saturated phase.
  • Invited lecture (Conferences):
    International Conference Magnetic Resonance: fundamental research and pioneering applications (MR 70), 23.-27.06.2014, Kazan, Russia
Registration No. 20827

Magnetic fields in Europe
Wosnitza, J.
  • Invited lecture (Conferences):
    Farewell Symposium of Jan Kees Maan, 23.05.2014, Nijmegen, The Netherlands
Registration No. 20826

Validation of closure models for interfacial drag and turbulence of horizontal segregated flows
Höhne, T.
Abstract: In the last decade, applications of Computational Fluid Dynamic (CFD) methods for nuclear applications received more and more attention, as they proved to be a valuable complementary tool for design and safety. The main interest towards CFD consists in fact in the possibility of obtaining detailed 3D complete flow-field information on relevant physical phenomena at lower cost than experiments. Typically free surfaces manifest as stratified and wavy flows in horizontal flow domain where gas and liquid are separated by gravity. Stratified two-phase flows are relevant in many nuclear applications, e.g. pipelines, main coolant lines, horizontal heat exchangers and storage tanks.

CFD simulations for free surface flows require the modeling of the non-resolved scales. For modeling of interfacial transfers it is necessary to select the adequate interfacial transfer models and to determine the interfacial area. The numerical solution can resolve the statistically averaged motion of the free surface (including waves) which may not be too small relatively to the channel height and to the characteristic length of the spatial discretization. However, the detailed structure of interacting boundary layers of the separated continuous phases and surface ripples cannot be resolved. Instead, its influence on the average flow must be modeled.

The development of a general model closer to physics and including less empiricism is a long-term objective of the activities of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) research programs. Such models are an essential precondition for the application of CFD codes to the modeling of flow related phenomena in nuclear facilities. Here local geometry independent models for mass, momentum, heat transfer, and scalar transport are developed and validated. The new formulation for the drag force at the free surface within the algebraic interfacial area density model (the FSD model inside AIAD) is one result of these activities.

A further step of improvement of modeling the turbulence is the consideration of sub-grid wave turbulence (SWT) that means waves created by Kelvin-Helmholtz instabilities that are smaller than the grid size. So fare in the present code versions they are neglected. However, the influence on the turbulence kinetic energy of the liquid side can be significantly large. A region of marginal breaking is defined according Brocchini and Peregrine (2001). In addition turbulence damping functions should cover all the free surface flow regimes, from weak to strong turbulence.

CFD validation of the new approach was done using experiments of the HZDR HAWAC channel. A discussion of the general requirements of such CFD grade experiments was performed. The CFD calculations were done using the Best Practice Guidelines for two-phase flow modeling. One result of the simulations was that the sub-grid wave turbulence which exists in the area of the free surface follows the slug formations. At the wavy front and back of the slugs the value of the sub-grid wave turbulence is the highest in the channel. The slug frequency analysis was done using fast Fourier transform (FFT). The characteristic slug frequency of the simulation was around 2.0 Hz, which corresponds roughly to the experimental value of approximately 2.4 Hz. The model improves the physics of the existing two fluid approaches and is already applicable for a wide range of industrial two phase flows.

More verification and validation of the approach is still necessary – more CFD grade experimental data are required for the validation.

Keywords: CFD, AIAD, HZDR, two-phase flow
  • Contribution to proceedings:
    CFD4NRS-5, Application of CFD/CMFD Codes to Nuclear Reactor Safety and Design and their Experimental Validation, Joint OECD/NEA & IAEA Workshop, 09.-11.09.2014, Zürich, Schweiz
  • Lecture (Conference):
    CFD4NRS-5, Application of CFD/CMFD Codes to Nuclear Reactor Safety and Design and their Experimental Validation, Joint OECD/NEA & IAEA Workshop, 09.-11.09.2014, Zürich, Schweiz
Registration No. 20823

Experimental Investigation of Horizontal Gas–Liquid Stratified and Annular Flow Using Wire-Mesh Sensor
Vieira, R. E.; Kesana, N. R.; Torres, C. F.; McLaury, B. S.; Shirazi, S. A.; Schleicher, E.; Hampel, U.
Abstract: Stratified and annular gas–liquid flow patterns are commonly encountered in many industrial applications, such as oil and gas transportation pipelines, heat exchangers, and process equipment. The measurement and visualization of two-phase flow characteristics are of great importance as two-phase flows persist in many fluids engineering applications. A wire-mesh sensor (WMS) technique based on conductance measurements has been applied to investigate two-phase horizontal pipe flow. The horizontal flow test section consisting of a 76.2 mm ID pipe, 18 m long was employed to generate stratified and annular flow conditions. Two 16 × 16 wire configuration sensors, installed 17 m from the inlet of the test section, are used to determine the void fraction within the cross section of the pipe and determine interface velocities between the gas and liquid. These physical flow parameters were extracted using signal processing and cross-correlation techniques. In this work, the principle of WMS and the methodology of flow parameter extraction are described. From the obtained raw data time series of void fraction, cross-sectional mean void fraction, time averaged void fraction profiles, interfacial structures, and velocities of the periodic structures are determined for different liquid and gas superficial velocities that ranged from 0.03 m/s to 0.2 m/s and from 9 m/s to 34 m/s, respectively. The effects of liquid viscosity on the measured parameters have also been investigated using three different viscosities. Registration No. 20820

Novel Cyclopentadienyl Tricarbonyl 99mTc Complexes Containing 1‑Piperonylpiperazine Moiety: Potential Imaging Probes for Sigma‑1 Receptors
Wang, X.; Li, D.; Deuther-Conrad, W.; Lu, J.; Xie, Y.; Jia, B.; Cui, M.; Steinbach, J.; Brust, P.; Liu, B.; Jia, H.
Abstract: We report the design, synthesis, and evaluation of a series of novel cyclopentadienyl tricarbonyl 99mTc complexes as potent σ1 receptor radioligands. Rhenium compounds 3-(4-(1,3-benzodioxol-5-ylmethyl)piperazin-1-yl)-propylcarbonylcyclopentadienyl tricarbonyl rhenium (10a) and 4-(4-(1,3-benzodioxol-5-ylmethyl)piperazin-1-yl)-butylcarbonylcyclopentadienyl tricarbonyl rhenium (10b) possessed high in vitro affinity for σ1 receptors and moderate to high selectivity for σ2 receptors and the vesicular acetylcholine transporter. Biodistribution studies in mice demonstrated high initial brain uptake for corresponding 99mTc derivatives [99mTc] 23 and [99mTc]24 of 2.94 and 2.13% injected dose (ID)/g, respectively, at 2 min postinjection. Pretreatment of haloperidol significantly reduced the radiotracer accumulation of [99mTc]23 or [99mTc]24 in the brain. Studies of the cellular uptake of [99mTc]23 in C6 and DU145 tumor cells demonstrated a reduction of accumulation by incubation with haloperidol, 1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine (SA4503), or 1,3-di-otolyl-guanidine (DTG). Furthermore, blocking studies in C6 glioma-bearing mice confirmed the specific binding of [99mTc]23 to σ1 receptors in the tumor. Registration No. 20817

Cyclotron based production of high specific activity [197(m)Hg]HgCl2
Walther, M.; Preusche, S.; Pietzsch, H.-J.; Bergmann, R.; Steinbach, J.
Abstract: 197mHg (T1/2 = 23.8 h, Eγ 133.98 keV, 33.5%) and 197Hg (T1/2 = 64.14 h, Eγ 77.4 keV, 18.7%) are gamma-emitting radionuclides suitable for SPECT imaging and of additional interest because of the potential therapeutic us of their Auger- and conversion electron emission. The unique chemical and physical properties as metal which forms water-stable carbon-metal bonds and the easy volatility awakened interest on mercury decades ago. The medical use of mercury was virtually complete after the scientific determination of the high toxicity and long biological half life of mercury compounds in vivo. From this follows that the condition precedent to develop new radiopharmaceuticals based on mercury radionuclides is their high specific activity. The production of nca 197Hg radionuclide together with the short lived 197mHg isomer is possible by proton or deuteron irradiation of natural gold using a cyclotron. The 197Au(p,n)197Hg reaction was applied until now only for small scale tracer production, beam monitoring or stacked foil measurements. The main goal of the research project is the evaluation of the cyclotron-based radionuclides 197Hg/197mHg regarding their suitability for diagnostics and therapy of tumors. First results of investigations concerning nca 197Hg/197mHg production and the development of bifunctional mercury chelate complexes stable in vivo will be reported.
  • Abstract in refereed journal:
    Nuclear Medicine and Biology 41(2014)7, 646
    DOI-Link: http://dx.doi.org/10.1016/j.nucmedbio.2014.05.018
  • Lecture (Conference):
    2nd International Symposium on TECHNETIUM and other RADIOMETALS in CHEMISTRY and MEDICINE (Terachem 2014), 10.-13.09.2014, Bressanone, Italy
Registration No. 20816

Pharmacological characterization of α-MSH-derivatives
Sihver, W.; Gao, F.; Jurischka, C.; Haase-Kohn, C.; Steinbach, J.; Carta, D.; Bolzati, C.; Calderan, A.; Pietzsch, J.; Pietzsch, H.-J.
Abstract: The melanocortin-1 receptor is known to be overexpressed in melanoma. Thus, it is a potential target for novel α-MSH peptide derivatives aiming at diagnosis and therapy of melanoma. In this study, NOTA-NCS was conjugated with two peptides: NAP-NS1, a linear peptide with 9 amino acids (Ahx-βAla-Nle-Asp-His-D-Phe-Arg-Trp-Gly-NH2) and NAP-NS2, a lactam bridge-cyclized peptide with 12 amino acids (ε-Ahx-β-Ala-cyclo(Lys-Glu-His-D-Phe-Arg-Trp-Glu)-Arg-Pro-Val-NH2) each with the sequence His-Phe-Arg-Trp for biological activity. Four α-MSH derivatives were investigated in competition assays in murine B16-F10 and human MeWo melanoma cells. (S)-p-NH2-Bn-NOTA (NOTA-NAP-NS1) labeled with 64Cu and 68Ga, showing no transchelation in the cysteine and histidine challenge, was applied in saturation assays. Determination of octanol/water partition coefficients suggested that [64Cu]Cu-NOTA-NAP-NS1 had high hydrophilicity, and in buffer and serum it was stable after 1 h and 24 h. NAP-NS1 and NOTA-NAP-NS1 showed higher affinity than the cyclic derivatives. Linking the chelate unit at the peptide was accompanied by some loss of affinity. Saturation studies with the labeled peptide resulted in Kd values in the lower nanomolar range for [64Cu]Cu-NOTA-NAP-NS1 and [68Ga]Ga-NOTA-NAP-NS1, respectively. Thus, both radiolabeled peptides appear to be promising for further investigations in animal melanoma models.

This research was supported by MIUR (PRIN 2008F5A3AF_002).
  • Abstract in refereed journal:
    Nuclear Medicine and Biology 41(2014)7, 637-638
    DOI-Link: http://dx.doi.org/10.1016/j.nucmedbio.2014.05.038
  • Lecture (Conference):
    2nd International Symposium on TECHNETIUM and other RADIOMETALS in CHEMISTRY and MEDICINE (Terachem 2014), 10.-13.09.2014, Bressanone, Italy
Registration No. 20815

Single-domain antibodies: Next-generation targeting vectors for molecular imaging
Zarschler, K.; Zscheppang, K.; Kapplusch, F.; Cordes, N.; Stephan, H.
Abstract: Single-domain antibodies (sdAbs) provide significant benefits over conventional antibodies and fragments thereof in terms of size, stability, solubility as well as tumour uptake and blood clearance. Thus, sdAbs have been identified as valuable next-generation targeting moieties for molecular imaging and drug delivery in the past years. Since these probes are much less complex than conventional antibody fragments, bacterial expression represents a facile method for production of sdAbs in large amounts as soluble and functional proteins. Herein we report on heterologous high-yield expression of substantial amounts of soluble and functional sdAbs, which have an antagonistic effect on their molecular target, the epidermal growth factor receptor (EGFR). Upon radiolabeling with Tc-99m using the tricarbonyl method, we evaluated binding specificity and affinity to human EGFR-expressing tumor cells. Furthermore, we describe bioconjugation of sdAbs to fluorescent nanoparticles and characterization of sdAb-nanoparticles conjugates covering in vitro cancer cell imaging, cell proliferation as well as EGFR phosphorylation and signaling. The herein highlighted valuable properties of radiolabeled sdAbs combined with tailored effector functions may result in innovative next-generation theranostics.
  • Abstract in refereed journal:
    Nuclear Medicine and Biology 41(2014)7, 628
    DOI-Link: http://dx.doi.org/10.1016/j.nucmedbio.2014.05.015
  • Poster:
    2nd International Symposium on TECHNETIUM and other RADIOMETALS in CHEMISTRY and MEDICINE (Terachem 2014), 10.-13.09.2014, Bressanone, Italy
Registration No. 20814

Peptide conjugates for EGFR-targeting
Viehweger, K.; Hesse, J.; Stephan, H.; Spiccia, L.; Graham, B.
Abstract: We have synthesized 64Cu-labelled peptide conjugates based on a 1,4,7-triazacyclononane (TACN) framework that may be applied for in vivo PET imaging. A peptide sequence (LARLLT, “D4”) was used to target the epidermal growth factor receptor (EGFR). Overexpression and mutations of this cell-surface receptor are involved in carcinogenesis and progression of many human cancers.

Four different linker groups were introduced to influence solubility and lipophilicity. The TACN-peptide conjugates are obtained in high yields after purification by RP-HPLC. Radiolabelling with 64Cu(II) was rapidly achieved under mild conditions (pH = 5.5; 22 °C). The receptor binding abilities of the labelled conjugates have been evaluated using immunoprecipitation and by determination of the dissociation constants, revealing only weak interactions (Kd > 100 nM) compared to its native ligand epidermal growth factor (EGF; Kd = 0.04 ± 0.002 nM). However, it was not determined if the “D4” peptide alone could target the EGFR.
  • Abstract in refereed journal:
    Nuclear Medicine and Biology 41(2014)7, 636
    DOI-Link: http://dx.doi.org/10.1016/j.nucmedbio.2014.05.045
  • Poster:
    2nd International Symposium on TECHNETIUM and other RADIOMETALS in CHEMISTRY and MEDICINE (Terachem 2014), 10.-13.09.2014, Bressanone, Italy
Registration No. 20813

Binding properties of radiolabeled cetuximab conjugates
Sihver, W.; Schubert, M.; Stephan, H.; Graham, B.; Spiccia, L.; Baumann, M.; Pietzsch, J.; Steinbach, J.; Pietzsch, H.-J.
Abstract: The monoclonal antibody cetuximab (C225) binds with high affinity to the epidermal growth factor receptor (EGFR), which is a major molecular target for treatment of different types of cancer. Radiolabeled C225 has been proven to be appropriate for cancer imaging and treatment. This study comprises an affinity comparison of different C225 conjugates incorporating p-SCN-Bn-NOTA (1), p-SCN-Bn-dipicolyl-TACN (2) and p-SCN-Bn-CHX-A″-DTPA (3). Evaluation of the Ki values using homogenates of A431 cells (EGFRhigh/Her2high expression) revealed minimal loss of affinity for these conjugates compared to unchanged C225. Saturation assays have been applied to compare the binding properties of ([64Cu]Cu-1)3-C225, ([64Cu]Cu-2)2-C225, ([90Y]Y-3)3-C225 and ([111In]In-3)3-C225 on homogenates of different cancer cell lines. The labeled conjugates were found to bind with high specificity and affinity to both the A431 and FaDu (EGFRmedium/Her2low expression) cells, however, the affinity for the FaDu was higher than for the A431 cells. The affinity of ([64Cu]Cu-1)3-C225 and ([64Cu]Cu-2)4-C225 for both EGFR expressing cell lines was somewhat higher than that displayed by ([90Y]Y-3)4-C225 and ([111In]In-3)3-C225. No specific binding was observed in the case of the EGFR-negative MDA-MB-453S cells. Moreover, immunoreactive fractions of more than 80% were determined, indicating that the conjugates are promising candidates for further in vivo evaluation.
  • Abstract in refereed journal:
    Nuclear Medicine and Biology 41(2014)7, 635
    DOI-Link: http://dx.doi.org/10.1016/j.nucmedbio.2014.05.037
  • Poster:
    2nd International Symposium on TECHNETIUM and other RADIOMETALS in CHEMISTRY and MEDICINE (Terachem 2014), 10.-13.09.2014, Bressanone, Italy
Registration No. 20812

In vitro evaluation of 64Cu-labeled GE11-conjugates
Oertel, F.; Starke, F.; Sihver, W.; Steinbach, J.; Pietzsch, H.-J.
Abstract: The epidermal growth factor receptor (EGFR) is frequently overexpressed in epithelial tumors and consequently represents an important target for cancer diagnosis and therapy. Recently, a novel peptide sequence (GE11, YHWYGYTPQNVI) was identified to bind the EGFR with high affinity in vitro (Kd = 22 nM) as well as in vivo [1]. These promising data suggest that a GE11-conjugate, which is radiolabeled with a positron-emitting radionuclide, may be used for the assessment of EGFR-levels of tumors and metastases by positron emission tomography, thus, identifying patients which can be medicated by anti-EGFR therapy. Therefore, the peptide-conjugates NOTA-linker-GE11, NOTA-linker-GE11-NH2 and TACN-(linker-GE11-NH2)3 (linker = NH-((CH2)2-O)2-(CH2)2-NH-CO-CH2-O-CH2-CO-βAla) were synthesized and radiolabeled with 64Cu at a radiochemical purity of at least 95%. All three radiolabeled GE11-conjugates were stable in buffer as well as in human blood serum. The binding properties of the radiolabeled conjugates were then evaluated in vitro using EGFR-rich (A431, FaDu) and EGFR-negative (MDA-MB-435s) cell preparations. However, as a result of the in vitro studies for all three GE11-conjugates no binding affinity could be determined. These findings may be explained by the highly hydrophobic character of the produced GE11-conjugates with accompanying tendency for aggregation.

[1] Z. Li, R. Zhao, X. Wu, et al.
FASEB J, 19 (2005), pp. 1978–1985
  • Abstract in refereed journal:
    Nuclear Medicine and Biology 41(2014)7, 634-635
    DOI-Link: http://dx.doi.org/10.1016/j.nucmedbio.2014.05.035
  • Poster:
    2nd International Symposium on TECHNETIUM and other RADIOMETALS in CHEMISTRY and MEDICINE (Terachem 2014), 10.-13.09.2014, Bressanone, Italy
Registration No. 20811

Bispidines as a platform for targeted multimodal imaging
Comba, P.; Hunoldt, S.; Morgen, M.; Pietzsch, J.; Steinbach, J.; Stephan, H.; Walther, M.
Abstract: Ligands based on 3,7-diazabicyclo[3.3.1]nonane (bispidine) form very stable coordination compounds, in particular with first row transition metal ions. Considering multiple functionalization, bispidines are promising candidates for pharmaceutical targeting and multimodal imaging. Due to the formation of thermodynamically stable and kinetically inert CuII complexes, penta- and hexadentate bispidine ligands are well suited for 64Cu positron emission tomography imaging and radiotherapy (64Cu/67Cu). The bispidine scaffold paves the way for introducing further functionalities, such as targeting units and fluorescence labels, which broadens the scope regarding pharmaceutical targeting and dual labelling (PET and optical imaging). Several bispidine ligands have been developed in order to improve the radiopharmaceutical behavior as well as possibilities for further beneficial functionalization. Variable denticity (tetra-, penta- and hexadentate) with different donor groups, such as amino, amido, pyridine and/or methoxypyridine functionalities allows for tuning properties such as complexation and lipophilicity. These ligands and the important properties of their CuII complexes, e.g., stabilities, ligand exchange kinetics, serum stability, partition coefficients ([64Cu]Cu-bispidine: n-octanol/water) and biodistribution studies will be reported.
  • Abstract in refereed journal:
    Nuclear Medicine and Biology 41(2014)7, 632-633
    DOI-Link: http://dx.doi.org/10.1016/j.nucmedbio.2014.05.047
  • Poster:
    2nd International Symposium on TECHNETIUM and other RADIOMETALS in CHEMISTRY and MEDICINE (Terachem 2014), 10.-13.09.2014, Bressanone, Italy
Registration No. 20810

Corporate governance and compliance of companies: changes in risk management?
Stiller, D.; Joehnk, P.
Abstract: The concept of corporate governance in enterprises is an important topic in business administration. The topic is gaining on importance in the last years through the economic and financial crisis in 2007 and the crisis of public deficit and governmental debt in Europe in 2010. This paper describes current national and international legal provisions and standards of corporate governance. A particular emphasis is placed on the differences and influence factors in risk management between Europe and the United States of America.
Keywords: corporate governance, compliance, risk management, regulation, automotive industry
  • Journal of International Scientific Publications: Economy & Business 8(2014)547, 554
Registration No. 20809

Kinetic inertness evaluation of copper complexes using gel electrophoresis techniques
Kubeil, M.; Zarschler, K.; Steinbach, J.; Stephan, H.
Abstract: The development of highly stable radiocopper complexes is one major challenge that seeks to further improved radiopharmaceuticals for medicinal applications. In many cases, radiocopper complexes suffer the fate of dissociation in vivo which is contributed to loss of the radionuclide resulting amongst others in an unspecific accumulation in non-target tissues and thus in poor target-to-background ratios. The kinetic lability has been addressed as major issue for transchelation or dissociation in vivo. Valuable information of kinetic inertness can be derived from non-physiological and non-radiotracer conditions e.g., ligand or metal ion challenge experiments, acid-assisted dissociation studies. Serum stability experiments are more suitable, since they are associated with in vivo conditions. Usually, the method of choice to measure the kinetic inertness involves a time-consuming radio-HPLC procedure. In contrast, we describe two reliable in vitro assays using standard gel electrophoresis techniques which provide a timesaving work-flow for measuring simultaneously a variety of copper-containing chelates. With this procedure, different radiocopper chelates can be evaluated and compared concerning their kinetic inertness using protein challenge assays. Moreover, both experiments are transferable not only to newly designed chelates, but also to conjugates containing targeting molecules such as peptides or proteins.
Keywords: copper complexes; radiocopper; Cu-64; kinetic inertness; transchelation; chelate; chelator; gel electrophoresis; SDS-PAGE; native PAGE; human serum; superoxide dismutase
  • Poster:
    2nd International Symposium on TECHNETIUM and OTHER RADIOMETALS in CHEMISTRY and MEDICINE (TERACHEM 2014), 10.-13.09.2014, Bressanone, Italy
  • Abstract in refereed journal:
    Nuclear Medicine and Biology 41(2014)7, 633-634
    DOI-Link: http://dx.doi.org/10.1016/j.nucmedbio.2014.05.028
Registration No. 20806

Cyclam with N-carbonxyethyl pendant arms as suitable radiocopper chelates
Kubeil, M.; Zarschler, K.; Pietzsch, J.; Stephan, H.; Comba, P.
Abstract: Cyclam (1,4,8,11-Tetraazacyclotetradecane) and its derivatives are powerful ligands for very stable complexes with (radio)copper(II) [1]. These chelators allow the functionalization of targeting molecules, e.g. peptides and/or fluorescence units, to construct effective radiopharmaceuticals for diagnostic and therapeutic purposes. In this context, 1,4,8,11-tetra(carboxymethyl)-1,4,8,11-tetraazacyclotetradecane (TETA) is used for the development of copper-based target-specific radiopharmaceuticals, although dissociation and transchelation occur in biological systems. In contrast, radiolabeling of the pentadentate cyclam ligands with a different number of N-carboxyethyl groups have not been reported so far. As a consequence, their copper(II) complexes have been synthesized [2]. Herein, we present a comprehensive study, dealing with the influence of the pendant arm length on structural properties, radiolabelling conditions, in vitro and in vivo stability, and compare these results with cyclam ligands bearing N-carboxymethyl pendant arms e.g., CuII-TETA.
The different number of N-carboxyethyl pendant arms at the cyclam backbone strongly influences the structure and stability of the copper complexes. TE2P is ideally suited as a copper(II)-chelating agent due to its fast complexation with radiocopper, the high kinetic inertness towards SOD and human serum as well as the excellent biodistribution behaviour. The facile N-functionalization of TE2P with a specific peptide produces an imaging tool with improved pharmaceutical targeting.

1. T. J. Wadas, E. H. Wong,G. R. Weisman,C. J. Anderson, Chem. Rev. 110, 2858 (2010).
2. P. Comba, F. Emmerling, M. Jakob, W. Kraus, M. Kubeil, M. Morgen, J. Pietzsch, H.
Stephan, Dalton Trans. 42, 6142 (2013).
  • Lecture (Conference):
    5th EuCheMS Chemistry Congress, 31.08.-04.09.2014, Istanbul, Turkey
Registration No. 20805

Characterization of circulating microparticle-associated CD39 family ecto-nucleotidases in human plasma
Jiang, Z. Gordon; Wu, Y.; Csizmadia, E.; Feldbrügge, L.; Enjyoji, K.; Tigges, J.; Toxavidis, V.; Stephan, H.; Müller, Christa E.; Mcknight, C. James; Moss, A.; Robson, Simon C.
Abstract: Phosphohydrolysis of extracellular ATP and ADP is an essential step in purinergic signaling that regulates key pathophysiological processes, such as those linked to inflammation. Classically, this reaction has been known to occur in the pericellular milieu catalyzed by membrane bound cellular ecto-nucleotidases, which can be released in the form of both soluble ecto-enzymes as well as being associated with exosomes. Circulating ecto-nucleoside triphosphate diphosphohydrolase 1 (NTPDase 1/CD39) and adenylate kinase 1 (AK1) activities have been shown to be present in plasma. However, other ecto-nucleotidases have not been characterized in depth. An in vitro ADPase assay was developed to probe the ecto-enzymes responsible for the ectonucleotidase activity in human platelet-free plasma, in combination with various specific biochemical inhibitors. Identities of ecto-nucleotidases were further characterized by chromatography, immunoblotting, and flow cytometry of circulating exosomes. We noted that microparticle-bound ENTPDases and soluble AK1 constitute the highest levels of ecto-nucleotidase activity in human plasma. All four cell membrane expressed E-NTPDases are also found in circulating microparticles in human plasma, inclusive of: CD39, NTPDase 2 (CD39L1), NTPDase 3 (CD39L3), and NTPDase 8. CD39 family members and other ecto-nucleotidases are found on distinct microparticle populations. A significant proportion of the microparticle-associated ecto-nucleotidase activity is sensitive to POM6, inferring the presence of NTPDases, either −2 or/and −3. We have refined ADPase assays of human plasma from healthy volunteers and have found that CD39, NTPDases 2, 3, and 8 to be associated with circulating microparticles, whereas soluble AK1 is present in human plasma. These ecto-enzymes constitute the bulk circulating ADPase activity, suggesting a broader implication of CD39 family and other ecto-enzymes in the regulation of extracellular nucleotide metabolism.
Keywords: Ecto-nucleotidase; CD39; ATP; ADP; Adenosine; Purinergic signaling; TLC Registration No. 20804

2,3-Diaryl-substituted indole based COX-2 inhibitors as leads for imaging tracer development
Laube, M.; Tondera, C.; Sharma, S. K.; Bechmann, N.; Pietzsch, F.-J.; Pigorsch, A.; Köckerling, M.; Wuest, F.; Pietzsch, J.; Kniess, T.
Abstract: A series of 2,3-diaryl-substituted indoles containing a fluorine or methoxy group was synthesized via Fischer indole synthesis, McMurry cyclization, or Bischler–Möhlau reaction to identify potential leads for positron emission tomography (PET) radiotracer development as well as for optical imaging. All 2,3-diaryl-substituted indoles possess autofluorescent properties with an emission maximum in a range of 443–492 nm, which is acceptable for biological studies in vitro and, in part, in vivo. The molecular structure of compounds 3a and 3j was confirmed by X-ray crystal structure analysis. COX inhibitory activity was evaluated by a fluorescence-based and enzyme immunoassay-based assay. Redox activity of all target compounds was also determined. All synthesized 2,3-diaryl-substituted indoles are inhibitors of COX-2 enzyme in the low micromolar range. Compounds 3e, 3f, 3g and 3m displayed a 30–40% inhibition of COX-2 at 0.1 µM concentration while compounds 3f and 3g also exhibited COX-1 inhibitory activity. Various compounds like 3g showed substantial antioxidative potential (RDIENE=2.85, RHAVA=1.98), an effect that was most measurable with methoxy-substituted compounds. With respect to PET radiotracer synthesis, OMe-containing compound 3j was selected as a promising candidate for carbon-11 labeling, and F-containing compound 3m as a lead for the development of a fluorine-18 labeled derivative. Registration No. 20801

Effects of pulmonary acid aspiration on the regional pulmonary blood flow within the first hour after injury: an observational study in rats
Richter, T.; Bergmann, R.; Pietzsch, J.; Mueller, M. P.; Koch, T.
Gastric aspiration events are recognized as a major cause of pneumonitis and the development of acute respiratory distress syndrome. The first peak in the inflammatory response has been observed one hour after acid-induced lung
injury in rats. The spatial pulmonary blood flow (PBF) distribution after an acid aspiration event within this time frame has not been adequately studied. We determined therefore PBF pattern within the first hour after acid aspiration.
Anesthetized, spontaneous breathing rats (n= 8) underwent unilateral endobronchial hydrochlorid acid instillation so that the PBF distributions between the injured and non-injured lungs could be compared. The signal intensity of the lung
parenchyma after injury was measured by magnetic resonance tomography. PBF distribution was determined by measuring the concentration of [68Ga]-radiolabeled microspheres using positron emission tomography.
Following acid aspiration, magnetic resonance images revealed increased signal intensity in the injured regions accompanied by reduced oxygenation. PBF was increased in all injured lungs (171 [150; 196], median [25%; 75%]) compared
to the blood flow in all uninjured lungs (141 [122; 159], P= 0.0078).
From the first minute until fifty minutes after acid-induced acute lung injury, the PBF was consistently increased in the injured lung. These blood flow elevation was accompanied by significant hypoxemia

Keywords: Acute lung injury, respiratory aspiration, positron emission tomography, pulmonary blood flow, magnetic resonance imaging Registration No. 20800

In Vivo Fluorescence Imaging and Urinary Monoamines as Surrogate Biomarkers of Disease Progression in a Mouse Model of Pheochromocytoma
Ullrich, M.; Bergmann, R.; Peitzsch, M.; Cartellieri, M.; Quin, N.; Erhart-Bornstein, M.; Block, Norman L.; Schalley, A. V.; Pietzsch, J.; Eisenhofer, G.; Bornstein, S. R.; Ziegler, C. G.
Abstract: Pheochromocytoma is a rare but potentially lethal neuroendocrine tumor arising from catecholamine producing chromaffin cells.Especially for metastatic pheochromocytoma,the availability of animal models is essential for developing novel therapies. For evaluating therapeutic outcome in rodent pheochromocytoma models reliable quantification of multiple organ lesions depends on dedicated small animal in vivo imaging, which is still challenging and only available at specialized research facilities. Here, we investigated whether whole-body fluorescence imaging and monitoring of urinary free monoamines provide suitable parameters for measuring tumor progression in a murine allograft model of pheochromocytoma. We generated an mCherry-expressing mouse pheochromocytoma cell line by lentiviral gene transfer. These cells were injected subcutaneously into nude mice to perform whole-body fluorescence imaging of tumor development. Urinary free monoamines were measured by liquid chromatography with tandem mass spectrometry. Tumor fluorescence intensity and urinary outputs of monoamines showed tumor growth-dependent increases (<0.001) over the 30 days of monitoring post tumor engraftment. Concomitantly, systolic blood pressure was increased significantly during tumor growth. Tumor volume correlated significantly (<0.001) and strongly with tumor fluorescence intensity (=0.946) and urinary outputs of dopamine (=0.952), methoxytyramine (=0.947), norepinephrine (=0.756) and normeta-nephrine (=0.949). Dopamine and methoxytyramine outputs allowed for detection of lesions at diameters below 2.3 mm. Our results demonstrate that MPC-mCherry cell tumors are functionally similar to human pheochromocytoma. Both tumor fluorescence intensity and urinary outputs of free monoamines provide precise parameters of tumor progression in this subcutaneous mouse model of pheochromocytoma. This animal model will allow for testing new treatment strategies for chromaffin cell tumors.
Keywords: Pheochromocytoma, Catecholamines, Metanephrines, LC-MS/MS, In vivo fluorescence imaging, Mouse pheochromocytoma cells Registration No. 20799

Biocompatibility and inflammatory response in vitro and in vivo to gelatin-based biomaterials with tailorable elastic properties
Ullm, S.; Krüger, A.; Tondera, C.; Gebauer, Tim P.; Neffe, Axel T.; Lendlein, A.; Jung, F.; Pietzsch, J.
Abstract: Hydrogels prepared from gelatin and lysine diisocyanate ethyl ester provide tailorable elastic properties and degradation behavior. Their interaction with human aortic endothelial cells (HAEC) as well as human macrophages (Mɸ) and granulocytes (Gɸ) were explored. The experiments revealed a good biocompatibility, appropriate cell adhesion, and cell infiltration. Direct contact to hydrogels, but not contact to hydrolytic or enzymatic hydrogel degradation products, resulted in enhanced cyclooxygenase-2 (COX-2) expression in all cell types, indicating a weak inflammatory activation in vitro. Only Mɸ altered their cytokine secretion profile after direct hydrogel contact, indicating a comparably pronounced inflammatory activation. On the other hand, in HAEC the expression of tight junction proteins, as well as cytokine and matrix metalloproteinase secretion were not influenced by the hydrogels, suggesting a maintained endothelial cell function. This was in line with the finding that in HAEC increased thrombomodulin synthesis but no thrombomodulin membrane shedding occurred. First in vivo data obtained after subcutaneous implantation of the materials in immunocompetent mice revealed good integration of implants in the surrounding tissue, no progredient fibrous capsule formation, and no inflammatory tissue reaction in vivo. Overall, the study demonstrates the potential of gelatin-based hydrogels for temporal replacement and functional regeneration of damaged soft tissue.
Keywords: Cyclooxygenases; Cytokines; Endothelial cells; Macrophages; Matrix metalloproteinases; Thrombomodulin Registration No. 20798

The Feasibility of direct measurement of the 44Ti(α, p)47V and 40Ca(α, p)43Sc reactions in forward kinematics at astrophysically relevant temperatures
Al-Abdullah, T.; Akhmadaliev, S.; Ayranov, M.; Bemmerer, D.; Dressler, R.; Elekes, Z.; Kivel, N.; Schmidt, K.; Schumann, D.; Sobiella, M.; Stowasser, T.; Takacs, M. P.; Zuber, K.
Abstract: Understanding the synthesis of radioactive 44Ti in the α-rich freeze-out following core-collapse supernovae may help to better interpret such explosive events. The γ-ray lines from the decay of 44Ti have been observed by space-based γ-ray telescopes from two supernova remnants. It is believed that the 44Ti(α,p)47V reaction dominates the destruction of 44Ti, while the 40Ca(α,p)43Sc reaction removes fuel from the main 44Ti production reaction 40Ca(α,γ)44Ti. Here we report on a possible technique to determine both reaction rates at astrophysically relevant energies in forward kinematics. The first reaction will be performed using a 1–10 MBq 44Ti target. Two important concerns are considered to make this study possible: The amount of stable Ti in the radioactive target, which will be prepared via spallation reactions at Paul Scherrer Institute (PSI), and the degree of radioactive contaminations in the experimental setup due to sputtered 44Ti atoms after intensive irradiations. Several online and offline measurements in parallel with Monte Carlo simulations were performed to investigate these issues. Registration No. 20797

Interaction of Slow Highly Charged Ions with Ultrathin Membranes
Wilhelm, R. A.; Gruber, E.; Ritter, R.; Heller, R.; Facsko, S.; Aumayr, F.
Abstract: Slow highly charged ions (HCI) are known as an efficient tool for surface nano structuring of various insulating and semi-conducting surfaces. We show here that slow HCI can also be used to perforate a free-standing carbon nano membrane (CNM) with a thickness of only 1 nm. In Fig. 1 (left) a helium ion microscopy (HIM) image shows ion induced pores with sizes of up to 15 nm in diameter and corresponding sputter yields of up to a few thousand atoms. Recent energy loss and charge exchange measurements on ions transmitted through a 1 nm thick CNM and free-standing Graphene reveal a strong dependence of the ion energy loss on charge exchange (see Fig. 1 (right)). Surprisingly two distinct exit charge state distributions are observed, i.e. one part of the ions is almost neutralized and the other part remains in very high charge states after transmission.
A simple model for charge state dependent energy loss of slow ions is compared to the mea- sured transmission data. The ions potential and kinetic energy dependence on pore formation is discussed in terms of charge exchange and energy loss.
  • Invited lecture (Conferences):
    17th International Conference Physics of Highly Charged Ions (HCI2014), 31.08.-05.09.2014, San Carlos de Bariloche, Argentinien
Registration No. 20795

Plasma-based nanotechnology against corrosion of organ pipes
Pelic, B.; Skorupa, W.
Abstract: Experiments have been undertaken to explore the improvement of aqueous corrosion of Cu-Zn, by applying plasma immersion ion implantation (PI3).
The atmospheric corrosion of the tongues within the reed pipes which consist of a Cu-20Zn alloy (namely brass) is strongly enhanced by traces of acid vapors (from wooden parts and glue) and also the alloy’s instability caused by dezincification. A significant improvement in corrosion resistance has been achieved by applying a 30 nm aluminum oxide film using pulsed laser deposition (PLD) and implanting nitrogen ions into the near surface and the interface regions. The influence of the implanted N+ into CuZn and F+ into TiAl samples on the corrosion process has been investigated. For the sample evaluation, different characterization methods including scanning electron microscope with energy dispersive X-ray spectroscopy (SEM / EDX), Auger electron spectroscopy (AES), Rutherford backscattering spectroscopy (RBS), and Dektak stylus profiling have been applied to determine the chemical composition, the elemental depth profiles, roughness and defect formation of the samples before and after exposure.

Keywords: Plasma immersion ion implantation (PI3), Pulsed laser deposition (PLD), corrosion of organ pipes, Cu-Zn alloys, PbSn alloys
  • Invited lecture (Conferences):
    Final conference of the EU research project ''EU-PANNA'', 04.09.2014, Berlin, Germany
Registration No. 20782

Photoemission studies of niobium and lead photocathodes using picosecond UV laser
Xiang, R.; Arnold, A.; Lu, P.; Murcek, P.; Teichert, J.; Vennekate, H.; Barday, R.
Abstract: We present the results of our investigations on superconducting photocathodes for supercondcuting rf injectors. Bulk niobium and lead film on niobium have been considered as the best candidates. The quantum efficiency (QE) at room temperature has been measured with 258 nm UV laser pulses of 14 ps duration. A QE of 10-4 has been obtained for the lead film. In order to improve the photoemission yield of niobium, new treatment methods, like Cs-activation and implantation with alkali metals, have been applied and the results are reported.
Keywords: photocathode, niobium, lead, quantum efficiency (QE)
  • Contribution to proceedings:
    the 36th International Free Electron Laser Conference (FEL 2014), 25.-29.08.2014, Basel, Switzerland
    Proceedings of FEL2014
  • Poster:
    the 36th International Free Electron Laser Conference (FEL 2014), 25.-29.08.2014, Basel, Switzerland
Registration No. 20779

The challenges of regional geochemistry to compositional data analysis from a methodological viewpoint
van den Boogaart, K. G.; Tolosana-Delgado, R.
Abstract: Regional Geochemistry is an important tool for the detect on of geopotenials (e.g. deposits) and risks (e.g. polution sources) and is an important source of geological insight on large scale. It is mainly concerned with geochemical data, which is inherently compositional. Modern compositional data analysis (CoDa) provides a lot of tools like distribution models, transforms, graphics, compositional geostatistics, imputation, compositional regression and linear models, outlier detection and robustness. However it does not yet provide tools for typical tasks in regional geochemistry, which among others are: maps of single components, anomaly detection and background definition, dealing with below detection limit, dealing with spatially varying geology and land use, working with surveys with too many components to explore all pairwise log ratios, calibration of instruments, collocated compositions, etc.. Ideally CoDa methods should be superior to classical statistical methods for geochemical data and it should thus be possible to simply replace the statistical methods in state-of-the-art geochemical practice by corresponding CoDa tools.The aim of the talk is to give a systematic account of how and why this is not yet occuring. For instance, single components maps are considered a key information in geochemistry, but spurious according to the doctrine of the Aitchison simplex. The compositional alternative would be to work with pairwise log ratios. However such compositional tools have other drawbacks, like e.g. too many pairs, mixing of different information on and no standard literature on their interpretation. Anomaly detection and spa! al factors are not yet sufficiently developed in the methodology research on CoDa. O$ en the application on of standard CoDa tools generates practical problems, like e.g. the identification of anomalies in a multivariate compositon will show a multitude of kinds of anomalies and we are confronted with many different sources and reasons for their occurrence. Par! ally CoDa methods need to be developed for tasks specific to geochemistry, and partly geochemists need to to develop a new thinking for interpreting the results of CoDa methods.From this systematic analysis we have deduced a set of key issues:
• The composition as a whole holds too much information at once. We need efficient methods to extract informative summaries with respect to geochemical tasks. This includes developing readable CoDa graphics and summaries for more than 30 components and multiple layers.
• The single component is understood in a completely different way by geochemists and CoDa-statistians. It is necessary to generate a joint view of this problem and then solve it.
• Enabling CoDa methods for below detection limit and measurement error issues including taylored callibration on for the needs of regional geochemistry.
• High level key publications of the proper use of compositional methods in a regional geochemistry context as reference for future geochemical publications.
• Specialized CoDa based so$ ware for geochemistry powerful enough to replace the existing tools.

Keywords: geochemical exploration, CODA, anomaly detection
  • Lecture (Conference):
    GeoMap Workshop, 17.06.-20.09.2014, Olomouc, Česká republika
Registration No. 20778

The 40Ca(α,γ)44Ti reaction studied by in-beam γ-spectroscopy and activation
Schmidt, K.; Akhmadaliev, S.; Anders, M.; Bemmerer, D.; Boretzky, K.; Caciolli, A.; Dietz, M.; Elekes, Z.; Fülöp, Z.; Gyürky, G.; Hannaske, R.; Junghans, Arnd R.; Marta, M.; Menzel, M.-L.; Schwengner, R.; Szücs, T.; Takász, M. P.; Wagner, A.; Wagner, L.; Yakorev, D.; Zuber, K.
Abstract: The radioactive nuclide 44Ti is believed to be produced in the α-rich freezeout preceding supernova explosions. The γ-rays from its decay have been observed in space-based γ-observatories for the Cassiopeia A and recently also SN 1987A supernova remnants. The rates of the nuclear reactions governing the production and destruction of 44Ti should therefore be known with high precision. Over the last years there have been various studies of the 40Ca(α,γ)44Ti reaction, which is dominating the 44Ti production in supernovae.
Using the α-beam of the 3-MV Tandetron at Dresden, the strengths of 40Ca(α,γ)44Ti resonance triplet at 4.5 MeV laboratory α-energy has been studied by in-beam γ-spectroscopy and activation. In addition, preliminary results of resonance strengths between 3.5 and 3.8 MeV will be presented.
The irradiated samples have been analyzed in the underground laboratory Dresden Felsenkeller. The target stoichiometry has been determined by nuclear reactions and by elastic recoil detection analysis (ERDA), whereby the strength of the Ep = 1.842 MeV resonance in the 40Ca(p,γ)41Sc reaction could be restudied.

Keywords: titanium-44, capture reaction, nuclear astrophysiscs
  • Poster:
    Nuclei in the Cosmos XIII 2014, 07.-11.07.2014, Debrecen, Hungary
  • Poster:
    Fifteenth International Symposium on Capture Gamma-Ray Spectroscopy and Related Topics, 25.-29.08.2014, Dresden, Deutschland
Registration No. 20775

Primo – Projekterfahrungen im Helmholtz-Zentrum Dresden-Rossendorf
Reschke, E.
Abstract: Primo ist eines der am meisten eingesetzten Discovery-Systeme weltweit. Im Helmholtz-Zentrum Dresden-Rossendorf entschied man sich für den Einsatz von Primo Total Care (https://www.hzdr.de/primo) Im Bericht werden die Projekterfahrungen dargestellt, von der Entscheidungsfindung bis zur Akzeptanz durch die Nutzer. Insbesondere werden die erfahrenen Vor- und Nachteile der Total Care-Installation dargestellt.
Keywords: Discovery system, Primo Total Care
  • Invited lecture (Conferences):
    Jahrestagung des AK Bibliotheken der Leibnitz-Gemeinschaft, 10.-12.09.2014, Bonn, Deutschland
Registration No. 20774

Die Bibliothek als Open Access-Kompetenzzentrum in einer außeruniversitären Forschungseinrichtung
Reschke, E.
Abstract: Open Access zu publizieren, ist noch nicht selbstverständlich für WissenschaftlerInnen in den außeruniversitären Forschungsgemeinschaften. Neue Publikationsmöglichkeiten erfordern neue, prozessbegleitende Services. Der Aufbau eines Open Access Kompetenzzentrums in der Bibliothek ist ein bereits erfolgreicher Weg, die WissenschaftlerInnen umfassend zu informieren und zu unterstützen. Welche Leistungen erbringt das Kompetenzzentrum und wie erwirbt es die notwendige Kompetenz? Im Fallbeispiel 2 soll dargestellt werden, welche administrativen Bereiche das Thema Open Access tangiert, wie diese Bereiche zusammenarbeiten und wie sich dieses Netz für seine Aufgaben qualifiziert.
Keywords: Open Access, Library management,
  • Invited lecture (Conferences):
    Open-Access-Tage 2014, 29.-30.09.2014, Köln, Deutschland
Registration No. 20771

Project NanoTrack - Untersuchung des Lebenszyklus von Nanopartikeln anhand von [45Ti]TiO2 und [105Ag] Ag0
Franke, K.; Hildebrand, H.; Schymura, S.
Keywords: NanoTrack Lebenszyklus Nanopartikeln Ti-45 TiO2 Ag-105 Ag0
  • Invited lecture (Conferences):
    27th Meeting of the DECHEMA/VCI-Working Party „Responsible Production and Use of Nanomaterials“, 04.09.2014, Frankfurt am Main, Deutschland
Registration No. 20768

Range assessment in particle therapy based on prompt γ-ray timing measurements
Golnik, C.; Hueso-González, F.; Müller, A.; Dendooven, P.; Enghardt, W.; Fiedler, F.; Kormoll, T.; Roemer, K.; Petzoldt, J.; Wagner, A.; Pausch, G.
Abstract: Proton and ion beams open up new vistas for the curative treatment of tumors, but adequate technologies for monitoring the compliance of dose delivery with treatment plans in real time are still missing. Range assessment, meaning the monitoring of therapy-particle ranges in tissue during dose delivery (treatment), is a continuous challenge considered a key for tapping the full potential of particle therapies. In this context the paper introduces an unconventional concept of range assessment by prompt-gamma timing (PGT), which is based on an elementary physical effect not considered so far: therapy particles penetrating tissue move very fast, but still need a finite transit time—about 1–2 ns in case of protons with a 5–20 cm range—from entering the patient’s body until stopping in the target volume. The transit time increases with the particle range. This causes measurable effects in PGT spectra, usable for range verification. The concept was verified by proton irradiation experiments at the AGOR cyclotron, KVICART, University of Groningen. Based on the presented kinematical relations, we describe model calculations that very precisely reproduce the experimental results. As the clinical treatment conditions entail measurement constraints (e.g. limited treatment time), we propose a setup, based on clinical irradiation conditions, capable of determining proton range deviations within a few seconds of irradiation, thus allowing for a fast safety survey. Range variations of 2 mm are expected to be clearly detectable.
Keywords: particle therapy, range assessment, prompt gamma, timing spectroscopy Registration No. 20767

Characterisation of graphite by automated mineral liberation analysis
Sandmann, D.; Haser, S.; Gutzmer, J.
Abstract: The beneficiation of graphite is very costly and energy intensive and can necessitate multiple processing steps, often including flotation. Products have to satisfy very stringent quality criteria. To decrease beneficiation costs, a careful characterisation of feed and concentrate materials is needed. This study elucidates the additional benefit of methods of automated SEM-based image analysis, such as mineral liberation analysis (MLA), in addition to ‘traditional’ methods [optical microscopy and X-ray powder diffraction (XRD)] for the analyses of graphite raw materials and processing products. Owing to the physical and chemical properties of the mineral graphite, samples require delicate sample preparation as well as particular backscattered electron (BSE) imaging calibration for automated image analysis. These are illustrated in this study. The results illustrate that SEM-based image analysis of graphite feeds and concentrates can provide accurate and reliable information for the graphite beneficiation process. This applies to both mineralogical characteristics and process relevant parameters.
Keywords: Graphite, Beneficiation, SEM-based image analysis, Modal mineralogy, Mineral association, Liberation, MLA Registration No. 20766

Tuning perpendicular anisotropy gradient in Co/Pd multilayers by ion irradiation
Greene, Peter K.; Osten, J.; Lenz, K.; Fassbender, J.; Jenkins, C.; Arenholz, E.; Endo, T.; Iwata, N.; Liu, K.
Abstract: The tunability of Ar+ ion irradiation of Co/Pd multilayers has been employed to create depthdependent perpendicular anisotropy gradients. By adjusting the Arþ kinetic energy and fluence, the depth and lateral density of the local structural modification are controlled. First-order reversal curve analysis through X-ray magnetic circular dichroism and conventional magnetometry studies shows that the local structural damage weakens the perpendicular anisotropy near the surface, leading to a magnetization tilting towards the in-plane direction. The ion irradiation method is complementary to and may be used in conjunction with, other synthesis approaches to maximize the anisotropy gradient.
Keywords: perpendicular anisotropy gradient ion irradiation Co\Pd multilayer Registration No. 20763

Spectroscopic investigation in high magnetic fields of the dilute nitride GaAsN
Eßer, F.; Drachenko, O.; Schneider, H.; Patanè, A.; Hopkinson, M.; Helm, M.
Abstract: As a member of the dilute nitride family, GaAsN is a highly interesting material system for many application purposes such as LEDs, lasers, solar cells, and infrared photodetectors because of the tuning possibility of these devices by the variation of the nitrogen content. An accurate description of this new material system involves the knowledge of the band structure and in particular the effective mass. Motivated by the inconsistency of previous results (e.g. [1, 2]), which can be traced down to the particular investigation method, we use several spectroscopy techniques in a series of GaAsN epilayers with 0.1 - 1 % of nitrogen. Cyclotron resonance spectroscopy, being the most direct method, reveals that the cyclotron resonance frequency is not significantly affected by the nitrogen doping and thus the effective mass. Magneto-photoluminescence, on the other hand, stems from several transitions, which are not resolved spectrally, but identified in time-resolved measurements. We discuss the different behaviour of these transitions in magnetic fields up to 7 T (static) and 41 T (pulsed). We find that the diamagnetic shift of the electron-to-carbon impurity transition cannot be always applied reliably to determine the electron effective mass. However, this method has been employed frequently in previous studies, which may explain the contradictory values reported in the literature.

[1] K. Alberi et al. Phys. Rev. Lett. 110, 156405 (2013)
[2] F. Masia et al Phys. Rev. B 73, 073201 (2006)

Keywords: Dilute nitride, GaAsN, effective mass, cyclotron resonance, magneto-photoluminescence, pulsed magnetic field
  • Lecture (Conference):
    International conference on the physics of semiconductors, 10.-15.08.2014, Austin, TX, USA
Registration No. 20761

The Evidence of Quasi-Free Positronium State in GiPS-AMOC Spectra of Glycerol
Zvezhinskiy, D.; Butterling, M.; Wagner, A.; Krause-Rehberg, R.; Stepanov, S. V.
Abstract: We present the results of processing of age-momentum correlation spectra that were measured for glycerol by the gamma-induced positron spectroscopy facility. Our research has shown that the shape of experimental s(t) curve cannot be explained without introduction of the intermediate state of positronium (Ps), called quasi-free Ps. This state yields the wide Doppler line near zero lifetimes. We discuss the possible properties of this intermediate Ps state from the viewpoint of developed model. The amount of annihilation events produced by quasi-free Ps is estimated to be less than 5% of total annihilations. In the proposed model, quasi-free Ps serves as a precursor for trapped Ps of para- and ortho-states.
Keywords: Positron Annihilation Spectroscopy, Bremsstrahlung, Positronium Registration No. 20760

Phase transitions of anisotropic and exchange origins in TmFe5Al7
Gorbunov, D. I.; Yasin, S.; Andreev, A. V.; Mushnikov, N. V.; Rosenfeld, E. V.; Skourski, Y.; Zherlitsyn, S.; Wosnitza, J.
Abstract: Magnetization and sound propagation reveal a number of unusual spontaneous and field-induced transformations in ferrimagnetic TmFe5Al7 (TC = 193 K). The rare-earth sublattice was found to provide a uniaxial magnetic anisotropy, whereas the iron sublattice favors an easy-plane anisotropy. A competition between them results in a first-order spin-reorientation transition at 64 K as the magnetic moments rotate from the c axis to the basal plane of a tetragonal structure. The transition is preceded by a first-order magnetization process of type II along the hard axis. Remarkably, the intersublattice Tm-Fe exchange interaction is weakened at the spin-reorientation transition. Concomitantly, the spontaneous magnetic moment disappears, and the ferrimagnetic state changes to antiferromagnetic. With increasing temperature, the strength of the Tm-Fe exchange is recovered, and the ferrimagnetism is restored at 82 K through another first-order phase transformation. Below 40 K, a first-order field-induced transition occurs for a magnetic field applied along the easy [001] axis. It reflects a rotation of the magnetic moments towards the forced ferromagnetic state observed above 30 T. Along the hard [100] axis the ferromagnetic saturation is not reached even at 60 T. Registration No. 20757

Observation of anisotropic exchange in a spin ladder by ESR
Čižmár, E.; Ozerov, M.; Krämer, K. W.; Rüegg, Ch.; Zvyagin, S. A.
Abstract: We report on high resolution X-band electron spin resonance (ESR) spectroscopy studies of the spinladder material (C5H12N)2CuBr4. Our experiments provide a direct evidence for the presence of anisotropy in (C5H12N)2CuBr4 in contrast to a fully isotropic spin-ladder model employed for this system previously. Low-temperature angular dependence of ESR transitions is analyzed employing a simple spin-1/2 dimer model with the symmetric anisotropic exchange interaction. Registration No. 20756

Uranyl sorption onto birnessite: A surface complexation modeling and EXAFS study
Rihs, S.; Gaillard, C.; Reich, T.; Kohler, S. J.
Abstract: This work investigates the mechanism of the uranyl interaction with birnessite, one of themost common layertype MnO2 mineral at the Earth's surface, by coupling macroscopic (surface complexation experiments) andmicroscopic (EXAFSmeasurements) approaches. The sorption of uranyl on synthetic hexagonal birnessite, the lowpH birnessite form, was studied under various conditions of pH (3–6), electrolyte backgrounds (0.1 M NaClO4, NaNO3 and Na2CO3), and solid/liquid ratios (from0.27 to 4.5 g/L). Sorption isotherms exhibit a complex form indicative of at least two types of sorption sites. EXAFS data reveal the presence of two equatorial O shells at ca. 2.32 Å and 2.46 Å for all the samples, and a Mn shell at ca. 3.38 Å in the low-pH (≤5) samples only. No U–U pair was detected, despite the presence of polynuclear dissolved species in some of the samples.
From the combination of the sorption isotherms and EXAFS results, a structural model for the sorption of uranyl onto hexagonal birnessite is proposed, in which two energetically different sites are involved. At low pH (≤5) a bidentate edge-sharing complex with Mn octahedra of the mineral edges can be inferred, whereas bidentate corner-sharing and/or monodentate complexation to layer vacancies would most likely describe EXAFS features of higher pH samples. A diffuse double layermodel of surface complexationwas developed for describing within the same framework the uranyl sorption against pH, involving both high-affinity (Mn octahedra edge) and lowaffinity (above layer vacancies) sites.
The comparison of the uranyl sorption onto hexagonal birnessite and various related environmental minerals shows that the affinity of uranyl for birnessite largely exceeds the sorption observed on montmorillonite and zeolite and turns out to be comparable to iron oxides, confirming the potential role of phyllomanganates to the control of uranyl mobility in post-oxic acidic environments.

Keywords: EXAFS U birnessite Registration No. 20755

Pathways for abiotic reduction in the FeS/Se(IV) and FeS2/Se(IV) systems
Breynaert, E.; Wangermez, W.; Dom, D.; Scheinost, A. C.; Parac-Vogt, T. N.; Kirschhock, C. E. A.; Maes, A.
Abstract: The geochemical behaviour and bio-availability of selenium have an unexpectedly intricate impact on modern society. While selenium is an essential micronutrient for many living organisms, the window between deficiency and toxicity is very narrow (0.04 ppm ; essential; 0.04 – 0.1 ppm beneficial; 3 ppm toxic). Due to its similarity to sulphur, it is commonly encountered in subsurface deposits such as coal and uranium, phosphate and sulphidic transitionmetal ores. The release of selenium to the environment is closely associated with the economic exploitation of such deposits. Because of its significant contribution to long-term radiation exposure, 79Se is considered as one of the important isotopes in the inventory of the long-lived radioactive waste produced by nuclear industry. In view of redox properties and abundant occurence in reducing soils and sediments, iron sulphides play an important role in the availability of mobile inorganic selenium in the environment.
While previous studies have demonstrated the formation of FeSe and Se0 upon reduction of Se(IV) with respectively iron monsulphides and iron disulphides, the mechanistic pathways explaining the different outcome are missing.
Combination of published results in a wide range of relevant systems [1-5] with new spectroscopic information (XAS and NMR spectroscopy) obtained for specifically synthesized key intermediates allows to rationalise all previous observations. These results allow to outline the different pathways and demonstrate how the intermediary selenium, sulphur and selenosulphur species determine the final outcome of the reactions.
[1] Scheinost et al (2008), ES&T, 42, 1984–1989
[2] Breynaert et al (2008), ES&T, 42, 3595–3601
[3] Scheinost et al (2008), J. Contam. Hydrol., 102, 228-245
[4] Breynaert et al (2010), ES&T, 44, 6649–6655
[5] Kang et al (2011), ES&T, 45, 2704–2710

Keywords: selenium EXAFS NMR nuclear waste
  • Lecture (Conference):
    Goldschmidt2014, 08.-13.06.2014, Sacramento, USA
Registration No. 20754

A radically new suggestion about the electrodynamics of water: Can the pH index and the Debye relaxation be of a common origin?
Volkov, A. A.; Artemov, V. G.; Pronin, A. V.
Abstract: The structure of pure water is commonly viewed as an openwork matrix of hydrogen-bonded H2O molecules with a Debye relaxation dynamics. The matrix is filled with free ions of low concentration, which makes water a weak electrolyte with pH = 7. Traditionally, the Debye relaxation is considered having no relevance to the dc water conductivity (or the pH index): while the Debye relaxation is caused by the dynamics of intact H2O molecules, the dc conductivity, in contrast, is due to self-dissociation of H2O into H3O+ and OH- ions. Here, we consider a microscopic mechanism, which could unify the Debye and the dc dynamics, namely the Brownian-like motion of strongly interacting ions. The model comprehensively describes the low-energy electrodynamics of water (up to 1011Hz) giving however an unexpected outcome: water behaves as if it had far more free ions than the standard model assumes. High concentration of counter charges results in a polarization structure of water. We recognize full well that such a radical model is contrary to many years of research on the dynamics, thermodynamics, and dielectric properties of water; but the results seem logically consistent and may prove stimulating. Registration No. 20751

Multiband transport and nonmetallic low-temperature state of K0.50Na0.24Fe1.52Se2
Ryu, H.; Wolff-Fabris, F.; Warren, J. B.; Uhlarz, M.; Wosnitza, J.; Petrovic, C.
Abstract: We report evidence for multiband transport and an insulating low-temperature normal state in superconducting K0.50Na0.24Fe1.52Se2 with Tc approximate to 20 K. The temperature-dependent upper critical field Hc2 is well described by a two-band BCS model. The normal-state resistance, accessible at low temperatures only in pulsed magnetic fields, shows an insulating logarithmic temperature dependence as T -> 0 after superconductivity is suppressed. This is similar as for high-Tc copper oxides and granular type-I superconductors, suggesting that the superconductor-insulator transition observed in high magnetic fields is related to intrinsic nanoscale phase separation. Registration No. 20750

Nonmetallic low-temperature normal state of K0.7Fe1.46Se1.85Te0.15
Wang, K.; Ryu, H.; Kampert, E.; Uhlarz, M.; Warren, J.; Wosnitza, J.; Petrovic, C.
Abstract: The normal-state in-plane resistivity below the zero-field superconducting transition temperature Tc and the upper critical field μ0Hc2 (T) was measured by suppressing superconductivity in pulsed magnetic fields for K0.70Fe1.46Se1.85Te0.15. The normal-state resistivity ρab is found to increase logarithmically with decreasing temperature as (T/Tc) → 0. Similar to granular metals, our results suggest that a superconductor-insulator transition below zero-field Tc may be induced in high magnetic fields. This is related to the intrinsic real-space phase-separated states common to all inhomogeneous superconductors. Registration No. 20749

Controlling Magnetic Order and Quantum Disorder in Molecule-Based Magnets
Lancaster, T.; Goddard, P. A.; Blundell, S. J.; Foronda, F. R.; Ghannadzadeh, S.; Moeller, J. S.; Baker, P. J.; Pratt, F. L.; Baines, C.; Huang, L.; Wosnitza, J.; Mcdonald, R. D.; Modic, K. A.; Singleton, J.; Topping, C. V.; Beale, T. A. W.; Xiao, F.; Schlueter, J. A.; Barton, A. M.; Cabrera, R. D.; Carreiro, K. E.; Tran, H. E.; Manson, J. L.
Abstract: We investigate the structural and magnetic properties of two molecule-based magnets synthesized from the same starting components. Their different structural motifs promote contrasting exchange pathways and consequently lead to markedly different magnetic ground states. Through examination of their structural and magnetic properties we show that [Cu(pyz)(H2O)(gly)2](ClO4)2 may be considered a quasi-one-dimensional quantum Heisenberg antiferromagnet whereas the related compound [Cu(pyz)(gly)](ClO4), which is formed from dimers of antiferromagnetically interacting Cu2+ spins, remains disordered down to at least 0.03 K in zero field but shows a field-temperature Phase diagram reminiscent of that seen in materials showing a Bose-Einstein condensation of magnons. Registration No. 20748

Evolution of the Pauli spin-paramagnetic effect on the upper critical fields of single-crystalline KxFe2-ySe2-zSz
Wolff-Fabris, F.; Lei, H.; Wosnitza, J.; Petrovic, C.
Abstract: We have studied the temperature dependence of the upper critical fields µ0Hc2 of KxFe2-ySe2-zSz single crystals up to 60 T. The µ0Hc2 for H parallel to ab and H parallel to c decrease with increasing sulfur content. The detailed analysis using Werthamer-Helfand-Hohenberg theory including the Pauli spin-paramagnetic effect shows that µ0Hc2 for H parallel to ab is dominated by the spin-paramagnetic effect, which diminishes with higher S content, whereas µ0Hc2 for H parallel to c shows a linear temperature dependence with an upturn at high fields. The latter observation can be ascribed to multiband effects that become weaker for higher S content. This results in an enhanced anisotropy of µ0Hc2 for high S content due to the different trends of the spin-paramagnetic and multiband effect for H parallel to ab and H parallel to c, respectively. Registration No. 20747

DEM-Based Analysis of Interactions between Tectonics and Landscapes in the Ore Mountains and Eger Rift (East Germany and NW Czech Republic)
Andreani, L.; Stanek, K. P.; Gloaguen, R.; Krentz, O.; Domínguez-González, L.
Abstract: Tectonics modify the base-level of rivers and result in the progressive erosion of landscapes. We propose here a new method to classify landscapes according to their erosional stages. This method is based on the combination of two DEM-based geomorphic indices: the hypsometric integral, which highlights elevated surfaces, and surface roughness, which increases with the topographic elevation and the incision by the drainage network. The combination of these two indices allows one to produce a map of erosional discontinuities that can be easily compared with the known structural framework. In addition, this method can be easily implemented (e.g., in MATLAB) and provides a quick way to analyze regional-scale landscapes. We propose here an example of a region where this approach becomes extremely valuable: the Ore Mountains and adjacent regions. The lack of young stratigraphic markers prevents a detailed analysis of recent fault activity. However, discontinuities in mapped geomorphic indices coupled to the analysis of river longitudinal profiles suggest a tight relationship between erosional discontinuities and main tectonic lineaments.
Keywords: Eger Rift; Ore Mountains (Erzgebirge); geomorphic indices; tectonics; Germany (Saxony); Czech Republic Registration No. 20746

Fermi-surface topology of the iron pnictide LaFe2P2
Blackburn, S.; Prevost, B.; Bartkowiak, M.; Ignatchik, O.; Polyakov, A.; Foerster, T.; Cote, M.; Seyfarth, G.; Capan, C.; Fisk, Z.; Goodrich, R. G.; Sheikin, I.; Rosner, H.; Bianchi, A. D.; Wosnitza, J.
Abstract: We report on a comprehensive de Haas-van Alphen (dHvA) study of the iron pnictide LaFe2P2. Our extensive density-functional band-structure calculations can well explain the measured angular-dependent dHvA frequencies. As salient feature, we observe only one quasi-two-dimensional Fermi-surface sheet; i.e., a hole-like Fermi-surface cylinder around Gamma, essential for s+/- pairing, is missing. In spite of considerable mass enhancements due to many-body effects, LaFe2P2 shows no superconductivity. This is likely caused by the absence of any nesting between electron and hole bands. Registration No. 20745
Pages: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] [53] [54] [55] [56] [57] [58] [59] [60] [61] [62] [63] [64] [65] [66] [67] [68] [69] [70] [71] [72] [73] [74] [75] [76] [77] [78] [79] [80] [81] [82] [83] [84] [85] [86] [87] [88] [89] [90] [91] [92] [93] [94] [95] [96] [97] [98] [99] [100] [101] [102] [103] [104] [105] [106] [107] [108] [109] [110] [111] [112] [113] [114] [115] [116] [117] [118] [119] [120] [121] [122] [123] [124] [125] [126] [127] [128] [129] [130] [131] [132] [133] [134] [135] [136] [137] [138] [139] [140] [141] [142] [143] [144] [145] [146] [147] [148] [149] [150] [151] [152] [153] [154] [155] [156] [157] [158] [159] [160] [161] [162] [163] [164] [165] [166] [167] [168] [169] [170] [171] [172] [173] [174] [175] [176] [177] [178] [179] [180] [181] [182] [183] [184] [185]