Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

When operating Schottky diodes andr ectifying field-effect transistors in the saturation regime, where they show a sub-
linear response to incident THz power, they can be used as fast autorcorrelators yielding information on the pulse envelope. We report on autocorrelation measurements at 3.41 THz of high-power THz pulses for determination of the pulse duration and pulse structure. By fringe resolved measurements, the THz frequency of the pulse is also obtained. We develop a theoretical model for the rectification process and compare the performance of anantenna-coupled Schottky diode to a large-area field-effecttransistorrectifier. While the Schottky diode saturates earlier and can therefore be used for autocorrelation measurements at lower input power, antenna-less large-area field-effect transistors can be used for highest power levels - even at free electron lasers - and turn out to be very robust.

Ziel des Antrages ist die Entwicklung eines Systems (Apparatus for in-situ defect analysis, AIDA) zur Untersuchung und zur experimentellen Simulation der Defektentstehung in neuartigen, für die Energiewende relevanten Materialien. Das Besondere am AIDA-System ist, dass diese Untersuchungen/Simulationen im oberflächennahen Bereich bereits auf der atomaren Skala, d.h. in einem frühen Stadium der Defektentstehung erfolgen, sowie in-situ („live“-Messungen) und somit ein grundlegendes Verständnis der Defektentstehung erlauben.

Generic experimental and methodical investigations were carried out aiming at the systematical elucidation of physico-chemical mechanisms and their influence on thermo-hydraulic processes, which can occur during the sump circulation operation after loss-of-coolant accidents in PWR. In such cases, boric acid containing coolant with dissolved zinc, which is formed by corrosion of zinc-coated containment internals, may reach core regions with higher temperature (hot-spots).
The experimental studies done at semi-technical scale were focused on the influence of such zinc containing coolants on thermo-hydraulics at heating configurations similar to those inside the core of PWR. The impact of physico-chemical mechanisms on thermo-fluid-dynamical behavior of the coolant inside a 3×3 heating rod configuration with spacer segments was determined. As an initial condition, boric coolant with dissolved zinc was used at a fluid temperature in the range of 45...50°C.
During the heating of zinc-containing coolant, an increasing turbidity of the fluid caused by formed colloids was observed first, followed by the formation of several solid corrosion products consisting of zinc borates. In dependence of the temperatures of fluid and heatable surfaces, the solids showed a different behavior concerning their mobilization potential, density and ability to layer formation. Deposits occurred at the rod surfaces as well as at the spacer segments. They effected a hindered heat transfer from the rod surfaces to the fluid, an increasing head loss at the spacers and some changes of the flow distribution. In addition, quantifications of the formed solid corrosion products including a characterization of the released particles were done. Subsequently, investigations were expanded considering original zinc sources (zinc-coated gratings) and a 16×16 fuel rod dummy with a centered 8×8 heating rod configuration.
Summing up, achieved experimental results allow conclusions about the solubility behavior of zinc corrosion products in boric coolant as well as about the formation of solids and the effects thereof. Beside processes of deposit layer formation and particle release, effects like outgassing of air dissolved in the coolant and local subcooled boiling phenomena were observed, which can contribute to the remobilization of formed solids and may strengthen the mentioned mechanisms.

Der Vortrag widmet sich der Fragestellung, mit welchen Themen und in welcher Tiefe und Breite kerntechnische Ausbildung und Forschung derzeit in Deutschland stattfindet und wie die aktuellen Entwicklungsprognosen dazu sind. Im Zentrum stehen die Fragen: Welche Kompetenzen braucht Deutschland in Zukunft im Bereich nukleare Sicherheit, wie ist die kerntechnische Ausbildung an den Universitäten und Helmholtz-Einrichtungen zu sehen und welche Rolle spielt der Kompetenzverbund Kerntechnik?

Uranium-americium mixed oxides are considered as potential blankets for americium transmutation in fast neutron reactors. Their thermophysical properties and notably their melting behavior have not been properly assessed although required in order to evaluate the safety of these compounds under irradiation. In this study, we measured via laser heating the melting points under inert atmosphere (Ar) of U1 xAmxO2±δ samples with Am/(U+Am) contents equal to 10, 15 and 20 mol.%. The experimental atmosphere was chosen in order to maintain, as much as possible throughout the heating/cooling cycles, the oxygen-to-metal ratio, initially set very close to 2.00. Structural characterizations of the samples carried out before and after melting confirm that this goal was satisfactorily attained. The obtained melting/solidification temperatures, measured here for the first time, indicate that under the current experimental conditions and as far as the investigated AmO2 contents, the solidus line of the UO2-AmO2 system follows with very good approximation the ideal solution behavior. Accordingly, the observed liquidus formation temperature decreases from 3130 ± 20 K for pure UO2 to 3051 ± 30 K for U0.8Am0.2O2±δ.

Kreiselpumpen kommen im Kraftwerksbereich in vielfältiger Weise zum Einsatz. Sie werden unter anderem als Speisepumpen oder als Umwälzpumpen in Kühlkreisläufen genutzt. Neben hoher Effizienz bei geringem Energieverbrauch bieten sie ein Reihe weiterer Vorteile, wie zum Beispiel ruhiger und kontinuierlicher Förderstrom und hohe Haltbarkeit und Beständigkeit. Erfolgt der Einsatz auch in sicherheitsrelevanten Bereichen, wie z. B. in der Reaktornotkühlung von Kernkraftwerken, muss unbedingt ein störungsfreier und zuverlässiger Betrieb gewährleistet werden. Dies kann nicht mehr sichergestellt werden, wenn es bei der Förderung des Notkühlmittels zu einem Gaseintrag durch Hohlwirbelbildung im Kühlmittelreservoir kommt.
Die vorgestellte Arbeit erläutert zunächst das Problem des Gasmitrisses durch Hohlwirbelbildung. Anschließend werden experimentelle Untersuchungen von Hohlwirbeln und Einlaufgeometrien beschrieben und Maßnahmen zur Vermeidung von Hohlwirbeln vorgeschlagen. Es werden Möglichkeiten der numerische Modellierung von Hohlwirbeln beschrieben und mit den experiementellen Untersuchungen verglichen. Weiterhin werden ausgewählte Tests an nuklearen Armaturen erläutert. Darüber hinaus werden die Auswirkungen des Gaseintrages in sicherheitsrelevante Systemkomponenten, wie Kreiselpumpen und Armaturen mittels tomographischen Untersuchungen aufgeschlossen und analysiert und es werden vorbeugende Maßnahmen vorgeschlagen. Auf den gewonnenen Ergebnissen basierend, können Betriebshinweise für Anlagenbetreiber optimiert werden. Darüber hinaus können verbesserte Design- und Auslegungsempfehlungen für sicherheitsrelevante Systemkomponenten erarbeitet und validiert werden.

A single crystal of U₃Fe₂Ge₇ was synthesized by the tin-flux method, and its structural and electronic properties were studied. The compound crystallizes in the orthorhombic crystal structure of La₃Co₂Sn₇ type with two Wyckoff sites for the U atoms. U₃Fe₂Ge₇ displays a ferromagnetic order below T_C = 62 K. Magnetization measurements in static (up to 14 T) and pulsed (up to 60 T) magnetic fields revealed a strong two-ion uniaxial magnetic anisotropy. The easy magnetization direction is along the c axis and the spontaneous magnetic moment is 3.3 μ_B per formula unit at 2 K. The moment per Fe atom is 0.2 μ_B, as follows from Mössbauer spectroscopy. The magnetic moments are oriented perpendicular to the shortest inter-uranium distances that occur within the zigzag chains in the ab plane, contrary to other U-based isostructural compounds. The magnetization along the a axis reveals a first-order magnetization process that allows for a quantitative description of the magnetic anisotropy in spite of its enormous energetic strength. The strong anisotropy is reflected in the specific heat and electrical resistivity that are affected by a gap in magnon spectrum.

The magnetic properties and the magnetocaloric effect (MCE) in TmZn have been studied by magnetization and heat capacity measurements. The TmZn compound exhibits a ferromagnetic state below a Curie temperature of TC=8.4K and processes a field-induced metamagnetic phase transition around and above TC. A giant reversible MCE was observed in TmZn. For a field change of 0-5T, the maximum values of magnetic entropy change (-ΔSMmax) and adiabatic temperature change (ΔTadmax) are 26.9J/kg K and 8.6K, the corresponding values of relative cooling power and refrigerant capacity are 269 and 214J/kg, respectively. Particularly, the values of -ΔSMmax reach 11.8 and 19.6J/kg K for a low field change of 0-1 and 0-2T, respectively. The present results indicate that TmZn could be a promising candidate for low temperature and low field magnetic refrigeration.

With increasing availability of proton and particle therapy centers for tumor treatment, the need for in-vivo range verification methods comes more into the focus. Imaging of prompt gamma rays emitted during the treatment is one of the possibilities currently under investigation. A knife-edge shaped slit camera was recently proposed for this task and measurements proved the feasibility of range deviation detection in homogeneous and inhomogeneous targets. In the present paper, we concentrate on laterally inhomogeneous materials, which lead to range mixing situations when crossed by one pencil beam: different sections of the beam have different ranges.
We chose exemplative cases from clinical irradiation and assembled idealized tissue equivalent targets. One-dimensional emission profiles were obtained by measuring the prompt gamma emission with the slit camera. It could be shown that the resulting range deviations can be detected by evaluation of the measured data with a previously developed range deviation detection algorithm. The retrieved value, however, strongly depends on the target composition, and is not necessarily in direct relation to the ranges of both parts of the beam. By combining the range deviation detection with an analysis of the slope of the distal edge of the measured prompt gamma profile, the origin of the detected range deviation, i.e.\ the mixed range of the beam, is also identified. It could be demonstrated that range mixed prompt gamma profiles exhibit less steep distal slopes than profiles from beams traversing laterally homogeneous material. For future application of the slit camera to patient irradiation with double scattered proton beams, situations similar to the range mixing cases are present and results could possibly apply.

Phosphodiesterase type 10A (PDE10A) is highly enriched in striatum and a novel drug target for several psychiatric and neurodegenerative diseases. PDE10A has additionally been implicated in the regulation of energy homeostasis, but the mechanisms remain unclear. Here, we showed marked levels of PDE10A in interscapular brown adipose tissue (BAT) of mice by utilizing small animal PET/MRI and the novel radioligand [¹⁸F]-AQ28A. In addition to BAT, Pde10a mRNA is also expressed in perigonadal visceral white adipose tissue (VAT). Pharmacological targeting of PDE10A with the selective inhibitor MP-10 increased [¹⁸F]-FDG uptake by BAT and enhanced thermogenesis in vivo. Moreover, acute MP-10 treatment of mouse brown adipocytes stimulated lipolysis and chronic treatment induced browning of primary human white adipocytes. Functional studies on diet induced obese mice further demonstrated that MP-10 produces weight loss independent of changes in food intake associated with increased energy expenditure and browning of VAT. Finally, human PET imaging with the radioligand [¹⁸F]-MNI-659 revealed marked levels of PDE10A in the supraclavicular region where brown/beige adipocytes are clustered in adults. Collectively, our findings highlight a novel thermoregulatory role for PDE10A in mouse and human adipocytes and promote PDE10A inhibitors as promising candidates for the treatment of obesity.

Es ist kein Abstract vorhanden.

A metal ion source prototype has been developed: a combination of magnetron sputter technology with 2.45 GHz electron cyclotron resonance (ECR) ion source technology—a so called magnetron ECR ion source (MECRIS). An integrated ring-shaped sputter magnetron with an Al target is acting as a powerful metal atom supply in order to produce an intense current of singly charged metal ions. Preliminary experiments show that an Al+ ion current with a density of 167 μA/cm2 is extracted from the source at an acceleration voltage of 27 kV. Spatially resolved double Langmuir probe measurements and optical emission spectroscopy were used to study the plasma states of the ion source: sputter magnetron, ECR, and MECRIS plasma. Electron density and temperature as well as Al atom density were determined as a function of microwave and sputter magnetron power. The effect of ECR heating is strongly pronounced in the center of the source. There the electron density is increased by one order of magnitude from 6 × 109 cm−3 to 6 × 1010 cm−3 and the electron temperature is enhanced from about 5 eV to 12 eV, when the ECR plasma is ignited to the magnetron plasma. Operating the magnetron at constant power, it was observed that its discharge current is raised from 1.8 A to 4.8 A, when the ECR discharge was superimposed with a microwave power of 2 kW. At the same time, the discharge voltage decreased from about 560 V to 210 V, clearly indicating a higher plasma density of the MECRIS mode. The optical emission spectrum of the MECRIS plasma is dominated by lines of excited Al atoms and shows a significant contribution of lines arising from singly ionized Al. Plasma emission photography with a CCD camera was used to prove probe measurements and to identify separated plasma emission zones originating from the ECR and magnetron discharge.

Der Vortrag zeigt die Entwicklung eines Recycling-Projektes für Gallium vom Labor- bis in den Pilotmaßstab und zeigt technologische, sowie ökonomische Aspekte. Das erfolgreiche Projekt der Freiberger Compound Materials GmbH mit den Forschungseinrichtungen TU Bergakademie Freiberg und Helmholtz-Institut Freiberg wurde 2014 mit dem Deutschen Rohstoff-Effizienzpreis ausgezeichnet.

QCD sum rules serve as tools to investigate changing hadronic properties in a hot and/or dense nuclear medium. The role of chiral symmetry breaking and restoration effects in a medium can be addressed also in the heavy-light meson sector. Thus, we consider Weinberg sum rules which refer to chiral partner mesons composed of a light and a heavy quark.

Wide band gap semiconductors (> 3.0 eV) like ZnO and TiO2 are widely investigated in the field of optoelectronics for ultraviolet lasers, heterojunction solar cells, thin film transistors and light emitting diodes. Nowadays, the transparent conductive oxides (TCO) like Al- or F-doped ZnO (AZO or FZO) are basic materials for the front contact in thin-film photovoltaics. A highly doped n-type ZnO thin layer is an attractive candidate to replace the much more expensive indium-tin-oxide layer in the microelectronics industry. The optoelectronic properties of TCOs are determined by the type of doping and carrier concentration. The n-type conductivity of ZnO is easily achieved by substitution of Zn by group III elements (Al, Ga, In), or by doping with halogen elements (F, Cl or I) substituting oxygen in the lattice site. In the case of TiO2 the n-type material can be achieved by doping with Nb, Ta or F ions while p-type TiO2 can be realized by e.g. Cr doping. Here, we will present the utilization of highly non-equilibrium thermal processing of TCO/Si heterojunctions using millisecond (ms) range flash lamp annealing (FLA) techniques for the structural modification and dopant activation to form highly doped p- and n-type TCOs films on silicon substrate. The n- and p-type doping in ZnO was made by incorporation of Al and F or N and P into ZnO, respectively. While the conductivity of TiO2 films was controlled by efficient incorporation of Ta and Cr into the lattice side of titania. It will be presented that via millisecond range FLA treatment not only the optoelectronic properties but also the crystallographic orientation and phase formation of TCOs can be modified. The optical properties of fabricated TCOs were investigated using temperature dependent photoluminescence, Raman and transmission spectroscopy. X-Ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM) were utilized to study the microstructural properties while the electrical properties of the TCO layers and heterojunctions were measured using Hall Effect and current-voltage characterization, respectively. Moreover, it is shown that the annealing atmosphere, even during ms range annealing, can efficiently passivates the surface state and bulk defects in the TCOs significantly improving the near band gap emission. - See more at: http://www.european-mrs.com/2015-fall-symposium-g-european-materials-research-society#sthash.tu4VYSCO.dpuf

The incorporation of different functional optoelectronic elements on a single chip enables performance progress, which can overcome the downsizing limit in silicon technology. For example, the use of Ge instead of silicon as a basic material in nanoelectronics would enable faster chips containing smaller transistors. In order to improve the device performance and fully exploit the unique properties of germanium, the germanium on insulator (GeOI) structure using the ultrathin body (UTB) GeOI architecture with an active doping concentration above 6×1019 cm-3 has to be explored. Here we present a new concept for the development, optimisation and fabrication of high-mobility channel materials based on Ge using plasma enhanced chemical vapour deposition of Ge and its recrystallization via millisecond range lateral explosive epitaxy. It is shown that the mechanism of explosive recrystallization (solid vs liquid) can be controlled by Sn co-doping and/or varying the annealing time. An influence of the explosive recrystallization and co-doping of Sn on the dopant activation efficiency and the carrier distribution in the ultra-thin GeOI and Ge NWs after millisecond range flash lamp annealing is discussed. Finally, the nanowire FETs will be presented. - See more at: http://www.european-mrs.com/2015-spring-symposium-z-european-materials-research-society#sthash.fI9UKy1b.dpuf

Nowadays, the transparent and conductive ZnO layer is a basic material for the front contact in thin-film photovoltaics. A highly doped n-type ZnO thin layer is an attractive candidate to replace the much more expensive indium-tin-oxide layer in the microelectronic industry. The optoelectronic properties of the ZnO are determined by the type of doping and carrier concentration. The n-type conductivity of ZnO is easily achieved by substitution of Zn by group III elements (Al, Ga, In), or by doping with halogen elements (F, Cl or I) substituting into the oxygen lattice site. Here we will present the utilisation of plasma immersion ion implantation (PIII) and millisecond range flash lamp annealing (FLA) techniques for the formation of highly p- and n-type ZnO films on silicon substrate. Whereas the n-type doping is made by incorporation of F into ZnO, the p-type ZnO films are obtained due to the PIII of N and P. Both p- and n-type dopants are activated using post-implantation millisecond range FLA process. The microstructural and opto-electrical investigations confirm the formation of a high-quality, highly-doped ZnO layer. Moreover the current-voltage characteristics show a heterojunction between ZnO and Si. It is shown that the SF6 plasma treatment efficiently passivates the surface state and bulk defects in the ZnO film significantly improving the near band gap emission from ZnO.

A key milestone for the next generation of high-performance microelectronic devices is the monolithic integration of germanium or III-V compound semiconductors with silicon technology. The incorporation of different functional optoelectronic elements on a single chip enables performance progress, which can overcome the downsizing limit in silicon technology. For example, the use of Ge or III-V compound semiconductors instead of silicon as a basic material in nanoelectronic would enable faster chips containing smaller transistors. Conventionally, the integration of III-V semiconductors or Ge with silicon is based on the heteroepitaxial growth of multi-layered structures on silicon or a variety of wafer bonding techniques [1]. Devices based on such structures combine the high carrier mobility and high luminescence efficiency of III-V semiconductors with the advantages of the well-developed silicon technology. On the other hand, the nearly 1D nanostructure of semiconductor nanowires offers a great potential for the future nanoelectronics. Silicon heteronanowires with integrated III-V segments are one of the most promising candidates for nanophotonic devices operating in the single-electron or single-photon regime [2]. Here we present the fundamental research on the physics of Ge micro- and nanostructures and III-V/Si hetero-nanowires to enable the integration of innovative Ge and III-V based devices for the main stream of Si CMOS technology. The proposed concept for the development, optimisation and fabrication of high-mobility channel materials is based on millisecond range explosive epitaxy performed with the flash lamp annealing (FLA) process.

We report on a cladding-like waveguide structure in Nd:YAG crystal fabricated by the multiple carbon ion beam irradiation. After the designed multiple irradiation process, the cladding-like waveguide with triple refractive-index layers were constructed in the region near the surface of the crystal. With such a structure, the waveguiding core was compressed and refractive index profile was modified, resulting in a higher light intensity than that of the single ion-beam-irradiated monolayer waveguide. The waveguide lasing at wavelength of 1064 nm was achieved with enhanced performance in the cladding-like structures with both planar and ridge configurations by the optical pump at 810 nm.

The photoactivity of TiO2 has been exploited in many applications ranging from photocatalysis, hydrogen production, pigments or solar cells [1]. However, optical absorption in TiO2 is mostly limited to the ultraviolet region of the solar spectrum (band-gap > 3 eV), triggering strong efforts to achieve visible-light (VISL) response by band-gap narrowing [1]. Non-metal (anion) doping seems to be a promising approach, as shown for the case of nitrogen (N) doped films [2]. However, it is unclear if the effective optical absorption of N-doped TiO2 is based on real band-gap narrowing or the formation of intragap localized states [3]. Recently, it has been argued that narrow-gap TiO2 would require heavy doping, relating VISL absorption to oxygen vacancies and color centers [4]. Another obstacle is the low thermodynamic solubility of dopants at substitutional sites [4]. This situation does not only compromise the effectiveness of band-gap narrowing but also provide recombination centers that are responsible for the loss of photogenerated electron-hole pairs [4]. A recent concept relies on N and Cr co-doping [5] to increase the solubility limit by non-compensated dopants where the opposite charge state of p- and n-type sites substantially enhances the thermodynamic kinetics of dopant pairs. In any case, a critical aspect of cation (co)doping relies in the introduction of large structural distortions in the host TiO2 matrix [4], needing processing or post-processing thermal treatments at moderate temperatures (~500ºC). In this work, we address the production and characterization of TiO2 (co)doped films by magnetron sputtering. We also compare different thermal annealing methods for further dopant activation and enhancement/design of the structural order, with special attention to the influence of as-grown films. The potential of novel rapid thermal processing such as flash-lamp annealing is also explored. The electronic structure of as-grown and modified films is assessed by means of X-ray absorption fine-structure and photoelectron spectroscopy, which permits the analysis of either (nano)crystalline or disordered structures. The optical response is derived from spectroscopic ellipsometry and transmission measurements. Finally, the structural, optical and electronic properties are correlated with the photocatalytic response of the samples. REFS: [1] M.A. Henderson, Surf. Sci. Rep. 66, 185 (2011); [2] R. Asahi et al. Science 293, 269 (2001) ; [3] M. Batzill et al. Phys. Rev. Lett. 96, 026103 (2006); [4] N. Serpone et al., J. Phys. Chem. B 110, 24287 (2006); [5] W. Zhu et al., Phys. Rev. Lett. 103, 226401 (2009)

The quality of recycled magnesium from chips depends strongly on their exposure to inorg. and org. impurities that are added during the prodn. processes. Different kinds of magnesium chips from these processes were analyzed by several methods. In addn., the accuracy and effectiveness of the methods are discussed. The results show that the chips belong either to the AZ91, AZ31, AM50​/60, or AJ62 alloy. Some kinds of chips show deviations from the above-​mentioned normations. Different impurities result mainly from transition metals and lime. The water and oil content does not exceed 25​%, and the chip size is not more than 4 mm in the diam. The sieve anal. shows good results for oily and wet chips. The detn. of oil and water shows better results for the application of a Soxhlet compared with the addn. of lime and vacuum distn. The most accurate values for the detn. of water and oil are obtained by drying at 110°C (for water) and washing with acetone (for oil) by hand.

At the near-neutral and reducing aquatic conditions expected in undisturbed ore deposits or in closed nuclear waste repositories, the actinides Th, U, Np and Pu are primarily tetravalent. These tetravalent actinides (An(IV)) are sparingly soluble in aquatic systems and, hence, are often assumed to be immobile. However, An(IV) could become mobile if they occur as colloids. This mini-review focuses on a new type of An(IV) colloids, oxyhydroxy silicate colloids. We herein discuss the chemical characteristics of these colloids and the potential implication for their environmental behavior. The binary oxyhydroxy silicate colloids of An(IV) could be potentially more mobile as a waterborne species than the well-known mono-component oxyhydrox-ide colloids.

Optical free-electron lasers (OFEL) based on the Traveling-wave Thomson scattering (TWTS) geometry [*] are realizable using existing petawatt class laser systems and electron beams from either conventional or Laser-wakefield accelerators. Such OFELs operate in the EUV to x-ray range, while at the same time remaining compact with centimeter to sub-meter total length.

Based on results from our analytical 1.5D-theory, as well as numerical investigations, we show using example scenarios that TWTS OFELs can be realized in SASE mode with existing RF sources such as ELBE at HZDR as well as Laser-wakefield accelerated electrons. We detail the necessary equipment for a TWTS OFEL experiment and discuss how current experimental limitations affect the design.

In Traveling-Wave Thomson-Scattering (TWTS) an optical, high-power laser pulse is scattered off a relativistic electron pulse to realize optical ree-electron lasers (OFELs) with a wavelength ranging from ultraviolet to Angstrom [*].

Such TWTS-OFELs optimally exploit the high spectral photon density in high-power laser pulses by spatially stretching the laser pulse and overlapping it with the electrons in a side scattering setup. The introduction of a laser pulse-front tilt provides for interaction lengths appropriate for FEL operation, so that beam electrons witness an undulator field of near-constant strength and wavelength over hundreds to thousands of undulator periods, thus giving enough time for self-amplified spontaneous emission (SASE) to seed the FEL instability and the realization of large laser gains.

In contrast to head-on OFEL schemes, TWTS-OFEL operates at sub-mm to mm effective undulator wavelength. Thus previous show-stoppers to OFELs due to small transverse coherence, large space charge or significant quantum effects are avoided. One of the key advantages of this approach is its scalability to x-ray wavelengths with existing lasers. We present the complete analytical description of the TWTS field and a self-consistent 1.5D theory of TWTS OFELs. We discuss the main scalings of resulting
TWTS OFELs with respect to electron and laser beam properties.

We show how all-optical free-electron lasers (OFELs) from EUV to the X-ray range can be realized using existing high-power lasers and electron accelerators.

Radiation spectra from Laser-Plasma interactions are straightforward to obtain in experiment, but due to the large number of simulated particles these are challenging to model ab-initio. Since the emitted spectra include the complete phase-space dynamics, they are a key to both designing and optimizing brilliant plasma-driven x-ray sources for applications such as ultra-short pump-probe experiments. We present angularly-resolved em-radiation spectra from all billions of particles in a laser-plasma simulation, including the full coherence properties from plasma structure and dynamics. These spectra range from far IR to X-rays. We show recent results from the multi-GPU, open-source code PIConGPU.

We use very similar methods, when designing optical free-electron lasers (OFELs) driven by Laser-wakefield accelerated (LWFA) electrons using both existing LWFA beams and OFEL driver lasers. Such optical FELs (OFELs) based on Traveling-wave Thomson scattering (TWTS) optimally exploit the high spectral photon density in high-power laser pulses by spatially stretching the laser pulse and overlapping it with the electrons in a side scattering setup. The introduction of a laser pulse-front tilt provides for interaction lengths appropriate for FEL operation. With careful dispersion control, electrons witness an undulator field of almost constant strength and wavelength over hundreds to thousands of undulator periods, thus giving enough time for self-amplified spontaneous emission (SASE) to seed the FEL instability and the realization of large laser gains.

Optical FELs (OFELs) based on Traveling-wave Thomson scattering (TWTS) optimally exploit the high spectral photon density in high-power laser pulses by spatially stretching the laser pulse and overlapping it with the electrons in a side scattering setup. The introduction of a laser pulse-front tilt provides for interaction lengths appropriate for FEL operation. With careful dispersion control, electrons witness an undulator field of almost constant strength and wavelength over hundreds to thousands of undulator periods, thus giving enough time for self-amplified spontaneous emission (SASE) to seed the FEL instability and the realization of large laser gains.
We provide an overview on the differences between TWTS OFELs, head-on OFEL designs and magnetic undulator FELs. In this dicussion we emphasize the respective impact on transverse coherence, quantum recoil and space-charge.

Selenium (Se) is an essential element that is required for biosynthesis of selenocysteine, the 21st proteinogenic amino acid in prokaryotes and eukaryotes. Se is toxic at high concentrations for most living organisms.1 Toxic high levels of Se, particularly in the form of selenite (SeO32-) in the environment, may be of natural or anthropogenic origin. In the natural environments, Se is subject to various microbial transformations which are important for bioremediation of Se species.2
For example, microbial reduction of toxic SeO32- to insoluble elemental selenium (Se0) results in its removal from water. Also, the reduction and methylation of SeO42- and SeO32- is considered an effective detoxification process, since the products (dimethylselenide [DMSe] or dimethyldiselenide [DMDSe]) are 500 to 700 times less toxic than SeO42- or SeO32-.3
Although a wide range of microorganisms have been investigated for their ability to transform selenium species, to our knowledge, aerobic methane-oxidising bacteria (which are ubiquitous in the environment and have numerous potential applications in remediation of organic and inorganic pollutants) have not previously been investigated for their ability to transform Se compounds.

Bis zum Jahr 2009 gab es immer wieder Diskussionen, ob es mit der Bibliothek am Helmholtz-Zentrum Dresen-Rossendorf weitergehen soll und wenn ja wie, insbesondere hinsichtlich der Personalstärke und des Raumbedarfs (Bibliothek als Ort in einer Forschungseinrichtung).
Daraufhin habe ich eine Bibliothekskonzeption für die Jahre 2010-2014 entwickelt, die zur Entscheidungsgrundlage wurde. Die Konzeption wurde von unserer Bibliothekskommission als richtungsweisend eingeschätzt und gegenüber dem Vorstand des Forschungszentrums zur Umsetzung empfohlen. Jetzt, 2015, können wir die vollständige Umsetzung der Konzeption berichten. Es gibt z.Z. keine Diskussionen um Bestand und Aufgaben der Bibliothek. Zwischen dem Vorstand, der Bibliothekskommission, unserem Zentralabteilungsleiter und der Bibliothek besteht Einvernehmen, dass sich zwar die Aufgaben der Bibliothek in ihrer Wichtung ändern, aber an der Notwendigkeit der Bibliothek vor Ort wird aktuell nicht gezweifelt.
Unterm Strich: Mit der gemeinsame Umsetzung der Konzeption wurde der Konflikt "Bibliothek brauchen wir-brauchen wir nicht" gelöst. Es entstand Planungssicherheit, die natürlich über den Zeitraum der Konzeptionsplanung hinaus weiter verteidigt/erkämpft werden muss.

Die Publikationsdatenbank im Helmholtz-Zentrum Dresden-Rossendorf wird seit 1992 geführt. Anfangs wurden nur bibliographische Daten erfasst. Mit den Jahren entstanden Bedürfnisse, mit diesen Daten mehr zu machen als Publikationslisten und es sollte keine doppelte Datenerfassung und Datenvorhaltung geben. Dafür mussten weitere Daten und Parameter in der einen Publikationsdatenbank erfasst werden. Der Genehmigungsworkflow wurde eingebaut, Controllingabfragen mussten möglich gemacht werden, wachsendes Berichtswesen erforderte zunehmende Flexibilität in den Abfragemöglichkeiten, Open Access Finanzierung, Verlinkung zur Datenarchivierung und weiteres. Ergebnis ist eine proprietäre Datenbankanwendung, basierend auf Oracle, die durch ihre Komplexität den Anforderungen aller beteiligten Akteure: Wissenschaftler, Bibliothek, wissenschaftliches Controlling, Institutsdirektoren und Vorstand, gerecht werden kann. Im Vortrag werden die verschiedenen Funktionen und die Organisation der Publikationsdatenbank vorgestellt.

Fracture toughness evaluation by the Master Curve method using 4-mm-thick miniature compact tension (mini-C(T)) specimens has been proposed. There were round robin exercises to validate the reference temperature, T0, determined on mini-C(T) of RPV base and weld metal. The HZDR has contributed to these round robin exercises. In addition to the mandatory testing, the distribution of the cleavage initiation sites over the crack front was determined. The mini-C(T) testing was also verified on RPV base metal 22 NiMoCr 3-7 from the lower ring of the non-commissioned Biblis C RPV. The fracture toughness values and therewith evaluated reference temperatures, T0, measured on 1T-, 0.5T-, 0.25T and 0.16T-C(T) specimens are compared. The results show that the T0 values determined with C(T) specimens of different size scatter within one standard deviation according to ASTM E1921. The testing of mini-C(T) specimens machined from the broken halves of Charpy specimens is a promising option to determine fracture toughness values of already tested surveillance specimens. The advantage of using mini-C(T) specimens is that material from the weld region can be investigated directly.

Die Immobilisierung von Tc(VII)/Tc(IV) an den Eisenphasen Magnetit und Siderit wurde mittels Batch-Sorptionsversuchen, ATR FT-IR-Spektroskopie und Röntgenabsorptionsspektroskopie untersucht.

A direct luminescence spectroscopic experimental setup for the determination of complex stability constants of mononuclear uranyl(VI) hydrolysis species is presented. The occurrence of polynuclear species is prevented using a low uranyl(VI) concentration of 10-8M (2.4 ppb). Time-resolved laser-induced fluorescence spectra were recorded in a pH range from 3 to 10.5. Deconvolution with parallel factor analysis (PARAFAC) resulted in three hydrolysis complexes. A tentative assignment was based on thermodynamic calculations: UO2+2 - 1:0 (aquo ion), UO2(OH)+ - 1:1, UO2(OH)2 - 1:2, UO2(OH)-3 - 1:3. An implementation of a Newton-Raphson algorithm into PARAFAC allowed a direct extraction of complex stability constants during deconvolution yielding log(ß1 M, 1 °C)1:1 =-4.4, log(ß1 M, 1 °C)1:2 =-11.7, log(ß1 M, 1 °C)1:3 =-21.6. Extrapolation to standard conditions gave: log(ß0)1:1 =-3.7, log(ß0)1:2 =-10.4 and log(ß0)1:3 =-20.1. Luminescence characteristics (band position, lifetime) of the individual mononuclear hydroxo species were derived to serve as reference data set for further investigations. A correlation of luminescence spectroscopic features with Raman frequencies was demonstrated for the mononuclear uranyl(VI) hydroxo complexes for the first time. Thereby a signal-to-structure correlation was achieved and the complex assignment validated.

Optical free-electron lasers (OFEL) based on the Traveling-wave Thomson scattering (TWTS) geometry are realizable using existing petawatt class laser systems and electron beams from either conventional or Laser-wakefield accelerators. Such OFELs operate in the EUV to x-ray range, while at the same time remaining compact.

Such TWTS OFELs optimally exploit the high spectral photon density in high-power laser pulses by spatially stretching the laser pulse and overlapping it with the electrons in a side scattering setup. The introduction of a laser pulse-front tilt provides for interaction lengths appropriate for FEL operation, so that beam electrons witness an undulator field of near-constant strength and wavelength over hundreds to thousands of undulator periods, thus giving enough time for self-amplified spontaneous emission (SASE) to seed the FEL instability and the realization of large laser gains.

Based on results from our analytical 1.5D-theory and numerical investigations, we discuss scaling laws and show using example scenarios that TWTS OFELs can be realized with existing RF sources such as ELBE at HZDR as well as LWFA electrons. We detail the necessary equipment for a TWTS OFEL experiment and discuss how current experimental limitations affect the design.

The interaction of an electron beam emerging from laser wakefield accelerators with an optical undulator allows for the realization of ultra-compact all-optical FELs and Compton sources using existing high-power lasers.
This presentation will review the various schemes considered to date with emphasis on both expected performance of the emitted radiation and challenges to face in terms of electron beam and laser pulse parameters.

BACKGROUND:

Signaling from integrins and receptor tyrosine kinases (RTKs) contributes substantially to therapy resistance of malignant tumors. We investigated simultaneous β1 integrin-epidermal growth factor receptor (EGFR) targeting plus radiotherapy in human head and neck squamous cell carcinomas (HNSCCs).
METHODS:

Ten HNSCC cell lines were grown in three-dimensional laminin-rich extracellular matrix cell cultures and two of them as tumor xenografts in nude mice (n = 12-16 per group). Targeting of β1 integrin and EGFR with monoclonal inhibitory antibodies (AIIB2 and cetuximab, respectively) was combined with x-ray irradiation. Clonogenic survival, tumor growth, and tumor control (evaluated by Kaplan-Meier analysis), apoptosis, phosphoproteome (interactome, network betweeness centrality analysis), receptor expression (immunohistochemistry), and downstream signaling (western blotting) were assessed. Various mutants of the integrin signaling mediator focal adhesion kinase (FAK) were employed for mechanistic studies. All statistical tests were two-sided.
RESULTS:

Compared with β1 integrin or EGFR single inhibition, combined β1 integrin-EGFR targeting resulted in enhanced cytotoxicity and radiosensitization in eight out of 10 tested HNSCC cell lines, which responded with an FAK dephosphorylation after β1 integrin inhibition. In vivo, simultaneous anti-β1 integrin/anti-EGFR treatment and radiotherapy of UTSCC15 responder xenografts enabled better tumor control compared with anti-EGFR monotherapy and irradiation (hazard ratio [HR] = 6.9, 95% confidence interval [CI] = 1.6 to 30.9, P = .01), in contrast to the SAS nonresponder tumor model (HR = 0.9, 95% CI = 0.4 to 2.3, P = .83). Mechanistically, a protein complex consisting of FAK- and Erk1-mediated prosurvival signals for radiation resistance, which was effectively compromised by β1 integrin and EGFR blocking.
CONCLUSIONS:

Concomitant targeting of β1 integrin and EGFR seems a powerful and promising approach to overcome radioresistance of HNSCCs.

there ist no abstract

In case of the incorporation of radioactive heavy metal ions, they would represent a serious health risk to humans due to their chemo- and/or radiotoxicity. Trivalent actinides (An(III)) like Am(III) or Cm(III) are man-made radioactive elements exclusively generated in nuclear reactors, whilst non-radioactive lanthanides (Ln(III)) are naturally occurring elements having wide technological and medical applications. These heavy metals have a potential risk of intake into humans with different pathways. Since Ln(III) and An(III) are considered to have no significant essential function in the human body, little is known about their biochemical behaviour from the uptake, in-vivo transport to the final accumulation or excretion.
Our recent studies on the speciation of U(VI) and Cm(III) in body fluids (e.g., saliva) suggested α-amylase as a potential binding partner of these actinides, which would finally affect the biochemical behaviour of these elements in-vivo. The enzyme α-amylase is one of the major enzymes in salivary and pancreatic secretions of mammals and catalyses the hydrolysis of polysaccharides like starch or glycogen. In order to further understand the potential role of α-amylase in the in-vivo speciation and complexation of Ln(III) and An(III), we investigated the complexation of Eu(III) and Cm(III) with α-amylase over a wide pH range by using time-resolved laser-induced fluorescence spectroscopy (TRLFS). Based on the obtained spectroscopic results, stability constants were determined at ambient and physiological temperature. The data were further extrapolated to infinite dilution to make the obtained data compatible with the existing thermodynamic database. The speciation of Eu(III) and Cm(III) in the saliva studied were determined based on these new data and will be presented.

there is no Abstract

S100A4, a member of the S100 protein family of EF-hand calcium-binding proteins, is overexpressed in various tumour entities, including melanoma, and plays an important role in tumour progression. Several studies in epithelial and mesenchymal tumours revealed a correlation between extracellular S100A4 and metastasis. However, exact mechanisms how S100A4 stimulates metastasis in melanoma are still unknown. From a pilot experiment on baseline synthesis and secretion of S100A4 in human melanoma cell lines, which are in broad laboratory use, A375 wild-type cells and, additionally, newly generated A375 cell lines stably transfected with human S100A4 (A375-hS100A4) or human receptor for advanced glycation endproducts (A375-hRAGE), were selected to investigate the influence of extracellular S100A4 on cell motility, adhesion, migration and invasion in more detail. We demonstrated that A375 cells actively secrete S100A4 in the extracellular space via an endoplasmic reticulum-Golgi-dependent pathway. S100A4 overexpression and secretion resulted in prometastatic activation of A375 cells. Moreover, we determined the influence of S100A4-RAGE interaction and its blockade on A375, A375-hS100A4, A375-hRAGE cells, and showed that interaction of RAGE with extracellular S100A4 contributes to the observed activation of A375 cells. This investigation reveals additional molecular targets for therapeutic approaches aiming at blockade of ligand binding to RAGE or RAGE signalling to inhibit melanoma metastasis.

A low temperature liquid metal model of the Czochralski (CZ) crystal growth process is considered experimentally for a high aspect ratio. Temperature fluctuations close to the edge of the model crystal are studied under the action of a rotating magnetic field (RMF) and/or rotation of the model crystal. A rotation of thermal structures is observed which loses its periodicity at sufficiently high strengths of the RMF. This finding is in qualitative agreement with previous findings in Rayleigh-Bénard (RB) cells. Opposing to that more generic case, the remaining amplitude of the temperature fluctuations stays significantly higher. I.e., the suppression of the fluctuations, which are detrimental to the growth of a mono-crystal, is weaker in the model under investigation.

A low temperature liquid metal model of the Czochralski crystal growth process is considered experimentally under conditions of high aspect ratio. In this paper we focus on the influence of a horizontal magnetic field (HMF) on the radial flow field and present first results from related model experiments. The flow is measured by means of the ultra-sound Doppler velocimetry (UDV).

Ultrasound velocity measurements were performed in a liquid metal flow (GaInSn) inside a cubic vessel. The flow was driven by the combined action of a rotating (RMF) and a travelling magnetic field (TMF) leading to an inherent three-dimensional electromagnetic force distribution in the fluid. As a result flow structures develop which are essentially determined by the frequency difference and the strength relation of both fields. The driving force is stationary for identical frequencies whereas it undergoes a slow temporal modulation in case of slightly varying frequencies. Beside the magnetic field parameter the alignment of the TMF’s to the fluid volume’s axis plays a crucial role. A novel ultrasound array system was used in the present study to measure two velocity components in two perpendicular planes (2d-2c) simultaneously. This contribution reports on the influence of axial alignment on the flow, and on the flow dynamics resulting from slightly different field frequencies of the RMF and the TMF.

The structural properties of the sodium actinide ternary oxides are reviewed in this work, and general trends among the series U-Np-Pu are identifed. A Rietveld refnement of monoclinic Na2PuO3, in space group C2~c, is reported for the first time, and the unsuspected existence of Na2NpO3 is revealed. In addition, the charge distribution in alpha-Na2UO4, Na3NpO4, alpha-Na2NpO4, Na4NpO5, Na5NpO6, Na2PuO3, Na4PuO5, and Na5PuO6 is investigated using X-ray Absorption Near-Edge Structure (XANES) spectroscopy at the U-L3, Np-L3, and Pu-L3 edges, respectively. In contrast to measurements in solution, the number of XANES data in the literature for neptunium and plutonium solid phases with a valence state higher than (IV) is very limited. The present results cover a wide range of oxidation states, namely (IV) to (VII), and can serve as a reference databank for future investigations. Finally, the sodium actinide series show a variety of local coordination geometries, and correlations between shape of the XANES spectra and local structural environment are discussed.

Moisture supply in the Pamir Mountains of Central Asia significantly determines the hydrological cycle and, as a result, impacts the local communities via hazards or socioeconomic aspects, such as hydropower, agriculture and infrastructure. Scarce and unreliable in situ data prevent an accurate assessment of moisture supply, as well as its temporal and spatial variability in this strongly-heterogeneous environment. On the other hand, a clear understanding of climatic and surface processes is required in order to assess water resources and natural hazards. We propose to evaluate the potential of remote sensing and regional climate model (RCM) data to overcome such issues.
Difficulties arise for the direct analysis of precipitation if the events are sporadic and when the amounts are low. We hence apply a harmonic time series analysis (HANTS) algorithm to derive spatio-temporal precipitation distributions and to determine regional boundaries delimiting areas where winter or summer precipitation dominate moisture supply. We complement the study with remote sensing-based products, such as temperature, snow cover and liquid water equivalent thickness. We find a strong intra- and inter-annual variability of meteorological parameters that result in strongly variable water budget and water mobilization. Climatic variability and its effects on floods and droughts are discussed for three outstanding years. The in-house developed HANTS toolbox is a promising instrument to unravel periodic signals in remote sensing time series, even in complex areas, such as the Pamir.

Advective and diffusive multiphase flows through vertical porous media are well examined and discussed in the scientific literature. However, uncommon configurations with inclined porous media are examined to a less extent, while advanced configurations with superimposed motion have hitherto only been addressed scarcely. An example for such configuration is the inclined rotating tubular fixed bed reactor, which is a novel intensified multiphase reactor for heterogeneous catalytic gas-liquid-solid reactions (H.-U. Härting, R. Lange, F. Larachi, M. Schubert, Chem. Eng. J. 2015, 281, 931).
For the prediction of liquid saturation and two-phase pressure drop in inclined and moderately fast rotating confined porous media, a two-fluid model is presented. The model is one-directional, isothermal and considers incompressible Newtonian fluids. To account for the interphase momentum transfer, adopted Ergun-type closures are formulated taking the peculiarities of stratified, dispersed and annular flow into account. The effects of inclination and rotation are incorporated as additional body forces, whereby inclination is taken into account by the longitudinal gravity component and an semi-empirical closure for the complex effects of the rotational velocity is presented. The applicability of the model is validated against experimental liquid saturation and two-phase pressure drop data.

PURPOSE:

How EGF receptor (EGFR) inhibition induces cellular radiosensitization and with that increase in tumor control is still a matter of discussion. Since EGFR predominantly regulates cell cycle and proliferation, we studied whether a G1-arrest caused by EGFR inhibition may contribute to these effects.
MATERIALS AND METHODS:

We analyzed human non-small cell lung cancer (NSCLC) cell lines either wild type (wt) or mutated in p53 (A549, H460, vs. H1299, H3122) and HCT116 cells (p21 wt and negative). EGFR was inhibited by BIBX1382BS, erlotinib or cetuximab; p21 was knocked down by siRNA. Functional endpoints analyzed were cell signaling, proliferation, G1-arrest, cell survival as well as tumor control using an A549 tumor model.
RESULTS:

When combined with IR, EGFR inhibition enhances the radiation-induced permanent G1 arrest, though solely in cells with intact p53/p21 signaling. This increase in G1-arrest was always associated with enhanced cellular radiosensitivity. Strikingly, this effect was abrogated when cells were re-stimulated, suggesting the initiation of dormancy. In line with this, only a small non-significant increase in tumor control was observed for A549 tumors treated with fractionated RT and EGFR inhibition.
CONCLUSION:

For NSCLC cells increase in radiosensitivity by EGFR inhibition results from enhanced G1-arrest. However, this effect does not lead to improved tumor control because cells can be released from this arrest by re-stimulation.

Isocitrate dehydrogenase (IDH) mutations are beginning to drive decisions on therapy for glioma patients. Here we sought to determine the impact of adjuvant treatment in patients with IDH-mutant, 1p/19q non-codeleted secondary high-grade astrocytoma (sHGA) WHO grades III/IV. Clinical data of 109 sHGA patients grades III/IV, in addition to IDH mutation-, 1p/19q-codeletion- and MGMT-promoter methylation status-were retrospectively analyzed. Survival analysis in relation to adjuvant treatment modalities and molecular profiling were performed. Out of 109 patients, 88 patients (80.7 %) harbored IDH mutations, 30 patients had a 1p/19q-codeletion (27.5 %) and 69 patients (63.3 %) exhibited a methylated MGMT-promoter status. At a median follow-up of 9.8 years, 62 patients (57 %) died. The postsurgical treatment included: radio-chemotherapy (RT-CT; 54.5 %), RT alone (19.3 %), and CT alone (22.7 %). The median overall survival (OS) in the entire group was 3.4 years (1.9-6.7 years). Patients who received RT-CT had a significantly longer OS compared with those who underwent RT alone (6.5 vs. 1.2 years, HR 0.35, CI 0.32-0.51, p = 0.011). In the IDH-mutant 1p/19q non-codeleted sHGA subgroup the RT-CT cohort had a significantly longer OS in comparison to the RT cohort (6.4 vs. 1.2 years, HR 2.7, CI 1.1-6.5, p = 0.022). In the stepwise multivariable Cox model for OS of all 88 IDH-mutant sHGA patients, survival was strongly associated with only one factor, namely, adjuvant RT-CT at diagnosis of a sHGA. This retrospective long-term study demonstrates that RT and CT (mostly PCV) significantly improves progression-free and overall survival in IDH-mutant secondary high-grade astrocytoma patients, regardless of 1p/19q-codeletion status.

Glioblastoma multiforme (GBM) is a highly aggressive and extremely lethal cancer and novel molecular therapies are required for optimized multimodal therapy regimes. While focal adhesion kinase (FAK) is regarded as a therapeutic target, its radiosensitizing potential remains to be elucidated in glioblastoma. Thus, FAK was inhibited using the pharmaco-logical inhibitor TAE226 and cytotoxicity and radiosensitization of glioblastoma cells were investigated in vitro. Monolayer and suspension cell cultures of a panel of glioblastoma cell lines (A172, LN229, U87MG, U138MG, U343MG, DD-HT7607, and DD-T4) were treated with increasing TAE226 concentrations (0-10 µM) alone or in combination with X-rays (0-6 Gy). Subsequently, clonogenic cell survival, expression and the phosphorylation of FAK downstream signaling, apoptosis and autophagy were analyzed. Efficient FAK inhibition by TAE226 mediated significant cytotoxicity and reduced sphere formation in a dose- and time-dependent manner. Two out of seven glioblastoma cell lines showed radiosensitization. Apoptotic induction by TAE226 was cell line-dependent. The results demonstrated that pharmacological FAK inhibitor TAE226 efficiently reduced clonogenicity and sphere formation in glioblastoma cells without generally modifying their radiosensitivity. However, future studies are necessary to define the potential of FAK inhibition by TAE226 or other pharmacological inhibitors in combination with radiochemotherapy.

Ferritic ODS 14Cr steels are one of the options for future nuclear and non-nuclear energy applications, in particular for components exposed to higher operation temperatures. In order to better exploit the potential advantages of ODS ferritic steels, such as improved creep strength and damage tolerance (with respect to non-ODS high-chromium steels) along with excellent oxidation resistance, a broader scientific and technical background is required. The present collaborative approach aimed to contribute to this background with respect to both fabrication issues and nano-/microstructurally based understanding of the resulting properties. In particular, the feasibility of ODS steel fabrication by means of spark plasma sintering on a semi-industrial scale was to be demonstrated. Parameter variations related to mechanical alloying, consolidation and thermal/mechanical treatments were covered. Hot extrusion was successfully applied to produce a 2.5 kg batch of ODS steel. Spark plasma sintering was scaled up towards semiindustrial 0.5 kg batches. A set of characterization techniques including Small-Angle Neutron Scattering, Transmission Electron Microscopy, Atom-Probe Tomography, Electron Probe Micro-Analysis, Electron Back-Scatter Diffraction and Transmission Kikuchi Diffraction as well as mechanical testing were applied to characterize the materials at different scales and stages of the fabrication process and to underpin the findings, such as a pronounced bimodality of grain size distributions, by observation-based understanding.

Kurzer Festvortrag bei der Feier 20 Jahre Helmholtz - 20 Highlights

Modern material combinations, which we use for converting, storing and saving energy, exploit the synergistic effects of multi-component systems to achieve functionalities beyond those of the single constituents alone. Steps towards a rational design of such material systems have increasingly inspired research activities both from experiment and theory. With the considerable increase of computational resources, simulations have successfully started to bridge the gap between idealized, rather specific theoretical concepts and experimental realization for system length and time scales, which reflect specific physical processes involved in energy saving, conversion, and storage. I will present examples from recent work which span the range the range from nano-scale battery effects in thin multifunctional oxide films of spongy structures by spinodal decomposition of silicon monoxide for storage and conversion to formation and stability of anti-wear coatings for energy efficient applications. Those studies illustrate recent developments to arrive at a truly scale- adapted modeling of energy materials.

There is no abstract available.

The authors present theoretical investigations of a k-restore process for damaged porous ultra-low-k (ULK) materials. The process is based on plasma enhanced fragmented silylation precursors to replace k-value damaging, polar Si-OH and Si-H bonds by k-value lowering Si-CH3 bonds. The authors employ density functional theory to determine the favored fragments of silylation precursors and show the successful repair of damaged bonds on our model system.

Amorphous atomically flat diamond-like carbon (DLC) coatings were produced by direct ion deposition using a system based on a Penning ion source, butane precursor gas and post acceleration. Hydrogen depth profiles of the DLC coatings were measured with the 15N R-NRA method using the resonant nuclear reaction ¹H(¹⁵N,alpha gamma)¹²C (E_res = 6.385 MeV). The films produced at 3.0-10.5 kV acceleration voltage show two main effects. First, compared to average elemental composition of the film, the near-surface region is hydrogen depleted. The increase of the hydrogen concentration by 3% from the near-surface region towards the bulk is attributed to a growth model which favours the formation of sp² hybridised carbon rich films in the film formation zone. Secondly, the depth at which the maximum hydrogen concentration is measured increases with acceleration voltage and is proportional to the penetration depth of protons produced by the ion source from the precursor gas. The observed effects are explained by a deposition process that takes into account the contributions of ion species, hydrogen effusion and preferential displacement of atoms during direct ion deposition.

Diamond-like carbon (DLC) coatings were deposited with a new direct ion deposition system using a novel 360 degree ion source operating at acceleration voltage between 4 and 8 kV. Cross-sectional TEM images show that the coatings have a three layered structure which originates from changes in the deposition parameters taking into account ion source condition, ion current density, deposition angles, ion sputtering and ion source movement. Varying structural growth conditions can be achieved by tailoring the deposition parameters. The coatings show good promise for industrial use due to their high hardness, low friction and excellent adhesion to the surface of the samples.

In May 2014 the first SRF photo injector at HZDR has been replaced by a new gun, featuring a new resonator and cryostat. The intention for this upgrade has been to reach for higher beam energies, bunch charges and therefore an increased average beam current, which is to be injected into the superconducting, CW ELBE accelerator, where it can be used for multiple purposes, such as THz generation or Compton back-scattering. Because of the increased bunch charge of this injector compared to its predecessor, it demands upgrades of the existing and/or novel approaches to alleviate the transverse emittance growth. One of these methods is the integration of a superconducting solenoid into the cryostat. Another method, the so called RF focusing, is realized by displacing the photo cathode’s tip and retracting it from the last cell of the resonator. In this case, part of the accelerating field is sacrificed for a better focus of the electron bunch right at the start of its generation. Besides particle tracking simulations, a recent study, investigating on the exact position of the cathode tip with respect to the cell’s back plane after tuning and cool down, has been performed.

There is no abstract.

Two-photon quantum-well photodetector devices designed for transition energies corresponding to 3 – 6 THz have been realized and intersubband energies were verified by photocurrent spectroscopy. Super-linear but not ideally quadratic behavior has been demonstrated by interferometric autocorrelation experiments using narrow-band terahertz pulses from the free-electron laser FELBE. With decreasing operation frequency, detector operation is progressively limited to low applied fields because of pronounced breakdown phenomena of the conductivity. This work has been supported by the Deutsche Forschungsgemeinschaft, project number SCHN 1127/2-1.

Integrated photonics is a key technology of the 21st century, and the electrically driven, integrated light emitter is an important building block, but difficult to realize. Thus, an enormous variety of different materials and material systems have been investigated in the past, ranging from the various approaches to integrate III-V semiconductors to the different types of Si-based light emission. Within the latter group rare earth (RE) implanted MOS structures feature a high conformity with standard CMOS processes combined with the excellent optical properties of RE elements. The present contribution discusses the problems of Si-based light emitters at the example of RE-doped MOS structures, and compares various light emitter designs and their potential to overcome these problems.
In detail, the power efficiency, the operation lifetime and the operation voltage of Tb- MOS structures are investigated. The main electroluminescence excitation mechanism is impact excitation of hot electron which plays an ambivalent role: efficient excitation is often related with efficient defect creation. In addition, a dark zone close to the injecting interface limits the scalability towards low voltages. The excitation mechanism und thus the performance of the light emitter is affected by the structure and composition of the dielectric stack of the MOS structure. Within this study, several host materials for the RE ions, namely stoichiometric and Si-rich silicon oxide or silicon nitride; different fabrication methods, namely plasma enhanced chemical vapour deposition, ion implantation and atomic layer deposition; and the use of additional buffer or injection layers are investigated.

Flash lamp annealing (FLA) is a modern annealing technique which takes advantage of the millisecond- and microsecond time scale. However, in many cases a direct temperature determination is sophisticated and complex, and sometimes an a priori guess of the temperature is desirable. In this work we simulate the space and time dependent temperature distribution during FLA and compare it with experimental results, e.g. with observable phase changes during the crystallization of amorphous Si layers on insulator for thin film transistor applications. In detail, we will address the following items: (i) the influence of multiple reflections within the layer system as well as between sample and chamber walls, (ii) the influence of lateral and transversal temperature gradients, and (iii) the edge overheating problem. Simulations were performed with the help of both in-house and commercial software tools.

BACKGROUND AND PURPOSE:

Delineation of clinical target volumes (CTVs) is a weak link in radiation therapy (RT), and large inter-observer variation is seen in breast cancer patients. Several guidelines have been proposed, but most result in larger CTVs than based on conventional simulator-based RT. The aim was to develop a delineation guideline obtained by consensus between a broad European group of radiation oncologists.
MATERIAL AND METHODS:

During ESTRO teaching courses on breast cancer, teachers sought consensus on delineation of CTV through dialogue based on cases. One teacher delineated CTV on CT scans of 2 patients, followed by discussion and adaptation of the delineation. The consensus established between teachers was sent to other teams working in the same field, both locally and on a national level, for their input. This was followed by developing a broad consensus based on discussions.
RESULTS:

Borders of the CTV encompassing a 5mm margin around the large veins, running through the regional lymph node levels were agreed, and for the breast/thoracic wall other vessels were pointed out to guide delineation, with comments on margins for patients with advanced breast cancer.
CONCLUSION:

The ESTRO consensus on CTV for elective RT of breast cancer, endorsed by a broad base of the radiation oncology community, is presented to improve consistency.

The need for novel, flexible and low-cost electronic products with functionality far beyond that offered by conventional size-restricted and rigid semiconductor devices requires a rapid development of advanced material and deposition technology concepts. One of the most promising pathways to realize this ambitious goal is printed flexible electronics (PFE). Recently, printing has successfully demonstrated its potential for manufacture of advanced low-cost electronic products such as flexible displays, thin-film solar cells, large-area sensors etc. Importantly, by using bendable, inexpensive media (e.g.: paper-like substrates, polymer films) and high-throughput roll-to-roll (R2R) processing, a significant reduction of the overall costs associated with electronic device fabrication has been achieved.
Here, we report on a successful application of millisecond thermal processing by flash lamp annealing (FLA) as a highly-attractive technique for the functionalization of copper paste screen printed on low-thermal budget paper-like media for package labelling. The effect of the FLA parameters (i.e. pulse duration and energy density), on the substrate behavior as well as on the microstructure and electrical response of the as-flashed films was studied. A significant drop of the sheet resistance of the FL-treated layers as compared to the as-printed layers was observed. As ms-FLA permits selective, near-surface heating, a damage of the sensitive substrates was avoided. The microstructure of the copper paste before and after FLA was also investigated. Being highly-efficient, “non-destructive, and compatible with R2R processing, FLA offers the realization of advanced PFE products.

Radiotherapy is a curative treatment option in prostate cancer. Nevertheless, patients with high-risk prostate cancer are prone to relapse. Identification of the predictive biomarkers and molecular mechanisms of radioresistance bears promise to improve cancer therapies. In this study, we show that aldehyde dehydrogenase (ALDH) activity is indicative of radioresistant prostate progenitor cells with an enhanced DNA repair capacity and activation of epithelial-mesenchymal transition (EMT). Gene expression profiling of prostate cancer cells, their radioresistant derivatives, ALDH(+) and ALDH(-) cell populations revealed the mechanisms, which link tumor progenitors to radioresistance, including activation of the WNT/β-catenin signaling pathway. We found that expression of the ALDH1A1 gene is regulated by the WNT signaling pathway and co-occurs with expression of β-catenin in prostate tumor specimens. Inhibition of the WNT pathway led to a decrease in ALDH(+) tumor progenitor population and to radiosensitization of cancer cells. Taken together, our results indicate that ALDH(+) cells contribute to tumor radioresistance and their molecular targeting may enhance the effectiveness of radiotherapy.

In this talk I will review the advances that subsecond thermal processing in the millisecond range using xenon-filled flash lamps (FLA) brings to the processing of advanced semiconductor materials, thus enabling the fabrication of novel electronic structures and materials. It will be demonstrated how such developments can translate into important practical applications via doping and/or defect engineering. A recent state-of-the-art is published in Ref./1/. An important issue of our present work is the liquid phase processing in the millisecond range at the surface of solid substrates. A recent example is the controlled formation of III-V nanocrystals (InAs, GaAs) in silicon nanowires after ion beam synthesis /2/. We prepared coarse grained dendritic crystal structures in thin silicon films on silicon dioxide to show that the addition of carbon prevents the agglomeration of the molten silicon films and largely influences the crystallisation process /3/. We could demonstrate that germanium and silicon exhibit superconductivity at ambient pressure and temperatures in the range of 1-2 K by avoiding Ga clusters /4/. Regarding photovoltaic applications, we dealt with the ion beam doping and thermal processing of PV silicon demonstrating a distinct improvement of the minority carrier diffusion length compared to rapid thermal processing and furnace treatments /5/. Moreover, we engineered the hydrogen content in photovoltaic silicon in correlation to the phosphorus doping using plasma immersion ion implantation and FLA /6/. Also, we demonstrated FLA driven phosphorus in-diffusion from a surface source /7/.

/1/ W. Skorupa and H. Schmidt: “Subsecond annealing of advanced materials”, Springer Series in Materials Science 192 (2014), ISBN 978-3-319-03131-6.
/2/ S.Prucnal,…,W.Skorupa et al.: “III–V semiconductor nanocrystal formation in silicon nanowires via liquid-phase epitaxy”, Nano Research 7, 1769 (2014); (see also Nano Lett. 11, 2814 (2011)).
/3/ M.Voelskow,…,W.Skorupa et al.: “Formation of dendritic crystal structures in thin silicon films on silicon dioxide by carbon ion implantation and high intensity large area flash lamp irradiation”, J. Cryst. Growth, 388, 70 (2014)
/4/ V.Heera,…,W.Skorupa et al.: “Depth-resolved transport measurements and atom-probe tomography of heterogeneous, superconducting Ge:Ga films”, Supercond.Sc.&Technol. 27, 055025 (2014).
/5/ S.Prucnal,…,W.Skorupa et al.: “Millisecond annealing for advanced doping of dirty-silicon solar cells”, J. Appl. Phys. 111, 123104 (2012).
/6/ F.L. Bregolin,…,W.Skorupa et al.:“Hydrogen engineering via plasma immersion ion implantation and flash lamp annealing in silicon-based solar cell substrates”, J. Appl. Phys. 115, 064505 (2014).
/7/ H.B. Normann,…,W.Skorupa et al.: “Phosphorus in-diffusion from a surface source by millisecond flash lamp annealing for shallow emitter solar cells”, Appl.Phys.Lett. 102, 132108 (2014).

This talk reviews the advances that subsecond thermal processing in the millisecond range using xenon-filled flash lamps (FLA) brings to the processing of advanced semiconductor materials, thus enabling the fabrication of novel electronic structures and materials. It will be demonstrated how such developments can translate into important practical applications via doping and/or defect engineering. A recent state-of-the-art is published in Ref./1/.
An important issue of our present work is the liquid phase processing in the millisecond range at the surface of solid substrates. A recent example is the controlled formation of III-V nanocrystals (InAs, GaAs) in silicon nanowires after ion beam synthesis /2/. We prepared coarse grained dendritic crystal structures in thin silicon films on silicon dioxide to show that the addition of carbon prevents the agglomeration of the molten silicon films and largely influences the crystallisation process /3/. We could demonstrate that germanium and silicon exhibit superconductivity at ambient pressure and temperatures in the range of 1-2 K by avoiding Ga clusters after ion implantation and FLA /4/. Regarding photovoltaic applications, we dealt with the ion beam doping and thermal processing of PV silicon demonstrating a distinct improvement of the minority carrier diffusion length compared to rapid thermal processing and furnace treatments /5/. Moreover, we engineered the hydrogen content in photovoltaic silicon in correlation to the phosphorus doping using plasma immersion ion implantation and FLA /6/. Also, we demonstrated FLA driven phosphorus in-diffusion from a surface source /7/.

/1/ W. Skorupa and H. Schmidt: “Subsecond annealing of advanced materials”, Springer Series in Materials Science 192 (2014), ISBN 978-3-319-03131-6.
/2/ S.Prucnal,…,W.Skorupa et al.: “III–V semiconductor nanocrystal formation in silicon nanowires via liquid-phase epitaxy”, Nano Research 7, 1769 (2014); (see also Nano Lett. 11, 2814 (2011)).
/3/ M.Voelskow,…,W.Skorupa et al.: “Formation of dendritic crystal structures in thin silicon films on silicon dioxide by carbon ion implantation and high intensity large area flash lamp irradiation”, J. Cryst. Growth, 388, 70 (2014)
/4/ V.Heera,…,W.Skorupa et al.: “Depth-resolved transport measurements and atom-probe tomography of heterogeneous, superconducting Ge:Ga films”, Supercond.Sc.&Technol. 27, 055025 (2014).
/5/ S.Prucnal,…,W.Skorupa et al.: “Millisecond annealing for advanced doping of dirty-silicon solar cells”, J. Appl. Phys. 111, 123104 (2012).
/6/ F.L. Bregolin,…,W.Skorupa et al.:“Hydrogen engineering via plasma immersion ion implantation and flash lamp annealing in silicon-based solar cell substrates”, J. Appl. Phys. 115, 064505 (2014).
/7/ H.B. Normann,…,W.Skorupa et al.: “Phosphorus in-diffusion from a surface source by millisecond flash lamp annealing for shallow emitter solar cells”, Appl.Phys.Lett. 102, 132108 (2014).

Im Rahmen eines vom Freistaat Sachsen über die Sächsische Aufbaubank geförderten Projektes haben wir uns mit der Anwendung der Nanotechnologie für den Korrosionsschutz von Blei-Zinn-Legierungen und Messing (Cu-Zn-Legierung) beschäftigt. Es wurde Dünnschichtabscheidung mittels gepulstem Laser bzw. Magnetronsputtern in Kombination zur Plasmaimmersions-Implantation verwendet. Es werden Ergebnisse von Laborstudien und Feldexperimenten in Kirchen für die beiden o.g. Legierungen berichtet, die effiziente Korrosionshemmung mit Dünnschichten im Dickenbereich <50 nm demonstrieren.

Im Rahmen eines vom Freistaat Sachsen über die Sächsische Aufbaubank geförderten Projektes haben wir uns mit der Anwendung der Nanotechnologie für den Korrosionsschutz von Blei-Zinn-Legierungen und Messing (Cu-Zn-Legierung) beschäftigt. Es wurde Dünnschichtabscheidung mittels gepulstem Laser bzw. Magnetronsputtern in Kombination zur Plasmaimmersions-Implantation verwendet. Es werden Ergebnisse von Laborstudien und Feldexperimenten in Kirchen für die beiden o.g. Legierungen berichtet, die effiziente Korrosionshemmung mit Dünnschichten im Dickenbereich <50 nm demonstrieren.

OBJECTIVE:

Research testing the concept of decision-making styles in specific contexts such as health care-related choices is missing. Therefore, we examine the contextuality of Scott and Bruce's (1995) General Decision-Making Style Inventory with respect to patient choice situations.
METHODS:

Scott and Bruce's scale was adapted for use as a patient decision-making style inventory. In total, 388 German patients who underwent elective joint surgery responded to a questionnaire about their provider choice. Confirmatory factor analyses within 2 independent samples assessed factorial structure, reliability, and validity of the scale.
RESULTS:

The final 4-dimensional, 13-item patient decision-making style inventory showed satisfactory psychometric properties. Data analyses supported reliability and construct validity. Besides the intuitive, dependent, and avoidant style, a new subdimension, called "comparative" decision-making style, emerged that originated from the rational dimension of the general model.
CONCLUSIONS:

This research provides evidence for the contextuality of decision-making style to specific choice situations. Using a limited set of indicators, this report proposes the patient decision-making style inventory as valid and feasible tool to assess patients' decision propensities.

Die klassische Orgel ist die wahrscheinlich komplexeste Errungenschaft des Abendlandes, da ihre Herstellung und Nutzung neben handwerklich-produktionstechnischen und wissenschaftlichen auch künstlerisch-ästhetische und religiöse Komponenten aufweist. Trotzdem unterliegt auch sie dem allbekannten Verfallsmechanismus der menschlichen Schöpfungen, in diesem Fall infolge Korrosion, die sich vor allem bei den metallischen Werkstoffen bemerkbar macht. Dies sind hauptsächlich Blei-Zinn-Legierungen und Messing (Cu-Zn-Legierung). Während die Bleikorrosion infolge von organischen Säuredämpfen (Essigsäure, Ameisensäure) schon Jahrhunderte bekannt ist, wurde die Korrosion von Messing im Orgelbau eher marginal berichtet. Eine der wesentlichen Ursachen für die Säuredämpfe liegt in der Verwendung von Holzkonstruktionen im Orgelbau, wobei vor allem Eichenholz aufgrund seines Essigsäuregehaltes kritisch ist.
Im Rahmen eines vom Freistaat Sachsen über die Sächsische Aufbaubank geförderten Projektes haben wir uns, nach unserem Wissen weltweit erstmals, mit der Anwendung der Nanotechnologie für den Korrosionsschutz der genannten metallischen Materialien beschäftigt. Es wurde Dünnschichtabscheidung mittels gepulstem Laser bzw. Magnetronsputtern in Kombination zur Plasmaimmersions-Implantation verwendet. Problematisch ist dabei auch, dass beide Legierungen wenig vakuumverträglich sind. Es werden Ergebnisse von Laborstudien und Feldexperimenten in Kirchen für die beiden o.g. Legierungen berichtet, die effiziente Korrosionshemmung mit Dünnschichten im Dickenbereich <50 nm demonstrieren.

This talk reviews the advances that subsecond thermal processing in the millisecond range using xenon-filled flash lamps (FLA) brings to the processing of advanced semiconductor materials, thus enabling the fabrication of novel electronic structures and materials. It will be demonstrated how such developments can translate into important practical applications via doping and/or defect engineering. A recent state-of-the-art is published in Ref./1/.
An important issue of our present work is the liquid phase processing in the millisecond range at the surface of solid substrates. A recent example is the controlled formation of III-V nanocrystals (InAs, GaAs) in silicon nanowires after ion beam synthesis /2/, see the contribution of S.Prucnal at this workshop. Further, we prepared coarse grained dendritic crystal structures in thin silicon films on silicon dioxide to show that the addition of carbon prevents the agglomeration of the molten silicon films and largely influences the crystallisation process /3/. We could demonstrate that germanium and silicon exhibit superconductivity at ambient pressure and temperatures in the range of 1-2 K by avoiding Ga clusters after ion implantation and FLA /4/. Regarding photovoltaic applications, we dealt with the ion beam doping and thermal processing of PV silicon demonstrating a distinct improvement of the minority carrier diffusion length compared to rapid thermal processing and furnace treatments /5/. Moreover, we engineered the hydrogen content in photovoltaic silicon in correlation to the phosphorus doping using plasma immersion ion implantation and FLA /6/. Also, we demonstrated FLA driven phosphorus in-diffusion from a surface source /7/.

/1/ W. Skorupa and H. Schmidt: “Subsecond annealing of advanced materials”, Springer Series in Materials Science 192 (2014), ISBN 978-3-319-03131-6.
/2/ S.Prucnal,…,W.Skorupa et al.: “III–V semiconductor nanocrystal formation in silicon nanowires via liquid-phase epitaxy”, Nano Research 7, 1769 (2014); (see also Nano Lett. 11, 2814 (2011)).
/3/ M.Voelskow,…,W.Skorupa et al.: “Formation of dendritic crystal structures in thin silicon films on silicon dioxide by carbon ion implantation and high intensity large area flash lamp irradiation”, J. Cryst. Growth, 388, 70 (2014)
/4/ V.Heera,…,W.Skorupa et al.: “Depth-resolved transport measurements and atom-probe tomography of heterogeneous, superconducting Ge:Ga films”, Supercond.Sc.&Technol. 27, 055025 (2014).
/5/ S.Prucnal,…,W.Skorupa et al.: “Millisecond annealing for advanced doping of dirty-silicon solar cells”, J. Appl. Phys. 111, 123104 (2012).
/6/ F.L. Bregolin,…,W.Skorupa et al.:“Hydrogen engineering via plasma immersion ion implantation and flash lamp annealing in silicon-based solar cell substrates”, J. Appl. Phys. 115, 064505 (2014).
/7/ H.B. Normann,…,W.Skorupa et al.: “Phosphorus in-diffusion from a surface source by millisecond flash lamp annealing for shallow emitter solar cells”, Appl.Phys.Lett. 102, 132108 (2014).

By combining secondary ion-mass spectrometry, transmission-electron microscopy (TEM) and Rutherford-backscattering spectrometry we show that the redistribution of implanted carbon atoms around epitaxially strained Si/SiGe layers results in their accumulation on the Si side and depletion on the SiGe side. On the contrary, uphill diffusion of carbon into SiSn layers takes place in the case of Si/SiSn structures. The TEM study demonstrates formation of dislocation loops, stacking faults and interstitial clusters in the Si/SiGe layers, but elimination of interstitial dislocation loops and suppression of tin precipitates in the Si/SiSn layers. We deduced different evolution of dislocation loops and a precipitate is due to dopant-defect complexes. The complex formation is enhanced by separation of implanted point defects in strain-fields of Si/SiSn and Si/SiGe layers.

In a next generation dynamo experiment currently under development at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) a fluid flow of liquid sodium, solely driven by precession, will be considered as a possible source for magnetic field generation. The experiment is mainly motivated by alternative concepts for astrophysical dynamos that are based on mechanical flow driving. For example, it has long been discussed whether precession may be a complementary power source for the geodynamo (Malkus, Science 1968) or for the ancient lunar dynamo due to the Earth-driven precession of the lunar spin axis (Dwyer, Nature 2011).

We will present the current state of development of the dynamo experiment together with results from non-linear hydrodynamic simulations with moderate precessional forcing. Our simulations reveal a non-axisymmetric forced mode with an amplitude of up to one fourth of the rotation velocity of the cylindrical container confirming that precession provides a rather efficient flow driving mechanism even at moderate precession rates.

More relevant for dynamo action might be free Kelvin modes (the natural flow eigenmodes in a rotating cylinder) with higher azimuthal wave number. These modes may become relevant when constituting a triadic resonance with the fundamental forced mode, i.e., when the height of the container matches their axial wave lengths. We find triadic resonances at aspect ratios close to those predicted by the linear theory except around the primary resonance of the forced mode. In that regime we still identify free Kelvin modes propagating in retrograde direction but none of them can be assigned to a triade.

Our results will enter into the development of flow models that will be used in kinematic simulations of the electromagnetic induction equation in order to determine whether a precession driven flow will be capable to drive a dynamo at all and to limit the parameter space within which the occurrence of dynamo action is most promising.

Epidermal growth factor receptor (EGFR) signaling plays an important role in tumor cell resistance to therapy. In addition to ligand binding, mutual and cooperative interactions of EGFR with integrin cell adhesion receptors critically influence proper downstream signaling through a number of bridging adapter proteins. In the present study, we analyzed the role of two of these adapter proteins, called PINCH1 and Nck2, for cellular radioresistance in combination with EGFR-targeting using the monoclonal antibody cetuximab. siRNA-mediated knockdown of PINCH1 or Nck2 resulted in enhanced radiosensitivity of 3D grown human squamous cell carcinoma cell lines FaDu (head and neck) and A431 (epidermis) comparable with effects seen after cetuximab treatment. Combination of knockdown and cetuximab did not result in additive nor synergistic effects regarding clonogenic radiation survival. Modifications in MAPK, Akt and FAK phosphorylation occurred upon cetuximab treatment as well as PINCH1 or Nck2 depletion. We further found this tumor cell radiosensitization to be due to attenuated repair of DNA double strand breaks and altered Rad50 and Nbs1 expression but without changes in other DNA repair proteins such as ATM, DNA-PK and Mre11. Our data suggest that the adaptor proteins PINCH1 and Nck2 critically contribute to cellular radioresistance and proper EGFR signaling in 3D lrECM grown human squamous cell carcinoma cells. Further investigations are warranted to identify the intracellular signaling network controlled by EGFR, PINCH1 and Nck2.

Overview over ion beam technology at HZDR

The crystal-field and exchange parameters are determined for the single-crystalline hydride ErFe₁₁TiH compound by analyzing the experimental magnetization curves obtained in magnetic fields of up to 60 T. By using the calculated parameters we succeeded in modeling theoretical magnetization curves for ErFe₁₁TiH up to 200 Т and to study in detail the transition from ferrimagnetic to a ferromagnetic state in the appliedmagnetic field.

An unexpected enhancement in the average, reduced γ-decay strength at very low -transition energies has been observed in in f p-shell nuclei as well as in the Mo region. Very recently, it has showed up in 138 La, which is, so far, the heaviest nucleus to display this feature. In this work, we present an experimental and theoretical overview of the low-energy enhancement. In particular, experimental evidence for the dipole nature of the enhancement, and shell-model calculations indicating strong, low-energy M 1 transitions are shown. Possible implications of this low-energy enhancement on astrophysical (n,γ ) reaction rates of relevance for the r-process nucleosynthesis are discussed.

The creation of molecular components for the use as electronic devices has made enormous progress. In order to advance the field further towards realistic electronic concepts, methods for the controlled modification of the conducting properties of the molecules contacted by metallic electrodes need to be further developed. Here we present a comprehensive study of charge transport in a class of molecules that allows modifications by introducing metal centers into organic structures. Single molecules are electrically contacted and characterized in order to understand the role of the metal centers in the conductance mechanism through the mo\-le\-cu\-lar junctions. It is shown that the presence of single metal ions modifies the energy levels and the coupling of the molecules to the electrical contacts, and that these modifications lead to systematic variations in the statistical behavior of transport properties of the molecular junctions. We apply a rigorous statistical analysis of thousands of junctions to reveal this correlation. The understanding of the role of the metal ion in the resulting conductance properties is an essential step towards the development of molecular electronic circuits.

An improved SRF gun (ELBE SRF gun II) has been installed and commissioned at HZDR. This new gun replaced the first SRF gun of the ELBE accelerator which had been in operation since 2007. The new gun has an improved 3.5-cell niobium cavity those SRF performances have been studied first with a copper cathode. After the replacement by our standard Cs2Tecathode we observed a tremendous degradation of the cavity gradient paired with an increase of field emission. In this contribution we will report on our in-situ investigations to find the origin and the reason for the particle contamination that happened during the first cathode transfer.

BACKGROUND:

Tumour hypoxia and a high tumour metabolism increase radioresistance in patients with head and neck squamous cell carcinoma (HNSCC). The aim of this study was to evaluate the correlation between hypoxia ([18F]HX4 PET) and glucose metabolism ([18F]FDG PET) molecular imaging.
MATERIAL AND METHODS:

[18F]HX4 and [18F]FDG PET/CT images of 20 HNSCC patients were acquired prior to (chemo)radiotherapy, in an immobilisation mask, with a median time interval of seven days (NCT01347281). Gross tumour volumes of the primary lesions (GTVprim) and pathological lymph nodes (GTVln) were included in the analysis. [18F]FDG PET/CT images were rigidly registered to the [18F]HX4 PET/CT images. The maximum and mean standardised uptake values (SUVmax, SUVmean) within both GTVs were determined. In addition, the overlap was compared between the [18F]HX4 high volume ([18F]HX4 HV) with a tumour-to-muscle ratio > 1.4 and the [18F]FDG high volume ([18F]FDG HV) with an SUV > 50% of the SUVmax. We report the mean± standard deviation.
RESULTS:

PET/CT scans including 20 GTVprim and 12 GTVlnwere analysed. There was a significant correlation between several [18F]FDG and [18F]HX4 parameters, the most pronounced being the correlation between [18F]FDG HV and [18F]HX4 HV (R = 0.93, p < 0.001). The fraction of the GTVprim with a high HX4 uptake (9 ± 10%) was on average smaller than the FDG high fraction (51 ± 26%; p < 0.001). In 65% (13/20) of the patients, the GTVprim was hypoxic. In four of these patients the [18F]HX4 HV was located within the [18F]FDG HV, whereas for the remaining nine GTVprim a partial mismatch was observed. In these nine tumours 25 ± 21% (range 5-64%) of the HX4 HV was located outside the FDG HV.
CONCLUSIONS:

There is a correlation between [18F]HX4 and [18F]FDG uptake parameters on a global tumour level. In the majority of lesions a partial mismatch between the [18F]HX4 and [18F]FDG high uptake volumes was observed, therefore [18F]FDG PET imaging cannot be used as a surrogate for hypoxia. [18F]HX4 PET provides complementary information to [18F]FDG PET imaging.

BACKGROUND:

Use of highly conformal radiotherapy in patients with head and neck carcinoma may lead to under-/overdosage of gross target volume (GTV) and organs at risk (OAR) due to changes in patients' anatomy. A method to achieve more effective radiation treatment combined with less toxicity is dose-guided radiotherapy (DGRT). The aim of this study was to evaluate discrepancies between planned and actually delivered radiation dose in head and neck patients and to identify predictive factors.
METHODS:

In this retrospective analysis, 20 patients with cT2-4 N0-3 M0 carcinoma originating from oropharynx, oral cavity, larynx and hypopharynx (Cohort 1), and seven patients with cT1-4 N0-3 M0 nasopharyngeal carcinoma (Cohort 2) treated with primary (chemo)radiotherapy and undergoing weekly kV-CBCT scans were included. Radiation dose was recalculated on 184 kV-CBCT images, which was quantified by D95% (GTV), Dmean (parotid and submandibular glands) and D2% (spinal cord). Predictive factors investigated for changes in these dose metrics were: gender, age, cT/N-stage, tumor grade, HPV-status, systemic therapy, body mass index at start of treatment, weight loss and volume change over the duration of the radiotherapy.
RESULTS:

There was no significant difference between the planned and delivered dose for GTV and OARs of Week 1 to subsequent weeks for Cohort 1. In Cohort 2, actually delivered Dmean to parotid glands was significant higher than planned dose (1.1 Gy, p = 0.002). No clinically relevant correlations between dose changes and predictive factors were found.
CONCLUSION:

Weekly dose calculations do not seem to improve dose delivery for patients with tumors of the oral cavity, oropharynx, larynx and hypopharynx. In patients with nasopharyngeal carcinoma, however, mid-treatment imaging may facilitate DGRT.

BACKGROUND:

A time factor of radiooncological treatment has been demonstrated for several tumours, most prominently for head and neck squamous cell carcinoma and lung cancer. In glioblastoma multiforme studies of the impact of postoperative waiting times before initiation of radio- or radiochemotherapy were inconclusive. Moreover analysis of the impact of overall treatment time of radiochemotherapy as well as overall duration of local treatment from surgery to the end of radiochemotherapy is lacking to date.
METHODS:

In this retrospective cohort study, we included 369 consecutive patients treated at our institution between 2001 and 2014. Inclusion criteria were histologically proven glioblastoma multiforme, age ≥ 18 years, ECOG performance status 0-2 before radiotherapy, radiotherapy or radiochemotherapy with 33 × 1.8 Gy to 59.4 Gy or with 30 × 2.0 Gy to 60 Gy. The impact of postoperative waiting time, radiation treatment time and overall duration of local treatment from surgery to the end of radiotherapy on overall (OS) and progression-free (PFS) survival were evaluated under consideration of known prognostic factors by univariate Log-rank tests and multivariate Cox-regression analysis.
RESULTS:

The majority of patients had received simultaneous and further adjuvant chemotherapy, mainly with temozolomide. Median survival time and 2-year OS were 18.0 months and 38.9% after radiochemotherapy compared to 12.7 months and 12.6% after radiotherapy alone. Median progression-free survival time was 7.5 months and PFS at 2 years was 14.3% compared to 6.0 months and 3.3%, respectively. Significant prognostic factors in multivariate analysis were age, resection status and application of simultaneous chemotherapy. No effect of the interval between surgery and adjuvant radiotherapy (median 27, range 11-112 days), radiation treatment time (median 45, range 40-71 days) and of overall time from surgery until the end of radiotherapy (median 54, range 71-154 days) on overall and progression-free survival was evident.
CONCLUSION:

Our data do not indicate a relevant time factor in the treatment of glioblastoma multiforme in a large contemporary single-centre cohort. Although this study was limited by its retrospective nature, its results indicate that short delays of postoperative radiochemotherapy, e.g. for screening of a patient for a clinical trial, may be uncritical.

Purpose/Objective:

Ion beams due to superior dose profile over photons and electrons may provide higher doseconformity and healthy tissue sparing. But due to high costs and huge size ion beam therapy is limited to a few centers only. A novel ion acceleration process via ultra-intense lasermatter interaction, promises size and cost reduction. However, laser-driven beams are characterized by intense particle bunches with peak dose rates exceeding conventional values by several orders of magnitude, low repetition rate, broad energy spread and large divergence, thus are diverse from conventional beams. This requires new solutions for developing Laser-based Ion Beam Therapy (LIBT) for clinical application. The presented work is a result of an ongoing joint translational research project of several institutions aiming to establish LIBT with protons and shows the status in five main challenges.

Materials and Methods:
I) Laser-based technology has been established, with protons (upto 20 MeV) via 150 TW laser system, for systematic radiobiological studies with human cell-lines and small animals with fixed beamline.
II) For translation towards patient irradiation, increase of proton energy from 20 to 230 MeV by increasing the laser power from 150 TW to ~1 PW is required and in progress.
III) Furthermore, a compact ion beam gantry system is designed based on pulsed magnets (PM), with integrated laser-particle acceleration chamber, novel beam capturing and energy selection system. A new pulsed scanning system for wide beams with broad energies is designed for irradiations with clinical accuracy.
IV) The light-weight iron-less high-field PMs are being developed for gantry realization. These are non-trivial and extremely challenging to design.
V) A new 3D TPS has been developed for new dose delivery and treatment planning strategies for LIBT.

Results:

No overall difference in the radiobiological effectiveness between laser-driven and conventional beams was detected to date. Therefore, a comparison of dose plans by treatment planning system is possible to evaluate the features of LIBT. The evaluation of treatment plans shows laser driven broad energetic beams are feasible for clinical application. Our double-achromatic 360° isocentric pulsed gantry design is ~2.5x smaller than conventional gantries (see fig.) and is capable of disperssionless scanning of high acceptance beams through 20x20 cm2 field size. For the realization, PMs have been designed and developed. A pulsed solenoid, for particle capturing and focusing, has been successfully tested at laser-driven beams. A novel 10 T compact pulsed 45° sector magnet has been developed and tested. Also, a pulsed high acceptance quadrupole with 250 T/m gradient is being developed.

Conclusions:

LIBT is a promising compact alternative and could change IBT, yet requires substantial development towards clinical application. Supported by German BMBF, no. 03Z1N511 & DFG cluster of excellence MAP.

We investigate the luminescence in a wide bandgap oxide, Mg-doped LiNbO3 and LiTaO3 , with both spectral and temporal resolution, enhancing the insight into the relaxation properties relevant in these materials.

Dilute magnetic semiconductors (DMSs) attracted great interests in the last several decades because of their potential for spintronic device [1]. III-V compounds especially GaAs based DMS has recently emerged as the most popular material for this new technology. However, that the low mobility of holes in p-type DMS limits the potential application in semiconductor spintronic devices. Therefore, the searching for n-type DMS is of interest.

The doping of Fe in InAs is attracting research attentions due to the possibility to fabricate n-type diluted magnetic semiconductors [2, 3]. However, the low solubility of Fe in InAs is the most difficulty to achieve InFeAs DMS. In this work, we obtain Fe doped InAs layers by ion implantation and pulsed laser annealing. This approach has shown success for preparing other III-V based DMSs [4, 5]. The formed InFeAs layers are proved to be epitaxial-like on InAs substrates. The prepared InFeAs layers reveal similar magnetic properties independent of their conductivity types. While the samples are lacking of charactersistics of DMS, they appear to be superparamagnetic behavior, revealing such as time-dependent magnetiszation measurements reveal aging and memory effects.

1. T. Dietl et al., Science 287, 1019-1022 (2000)
2. M. Kobayashi et al., Appl. Phys. Lett., 105, 032403(2014)
3. P. Nam Hai et al., Appl. Phys. Lett., 101, 182403 (2012)
4. D. Bürger et al., Phys. Rev. B, 81, 115202 (2010)
5. M. Khalid et al., Phys. Rev. B, 89, 121301(R) (2014)

Abstract Transport through the organic molecule 1,4-bis(phenylethynyl)-2,5-bis(ethoxy)benzene (PEEB) has been investigated using Density functional Theory (DFT) and the Non-Equilibrium Green's Function (NEGF) approach in order to explain results of experiments employing the mechanically controlled break junction (MCBJ) technique. The molecule was studied with various terminal groups (NH₂, SH and CN) which lead to different conductance values when attached to Gold electrodes. The effect of different contact geometries was studied in simulations, allowing predictions on the most likely contact geometries occurring in experiments.

Transport through the organic molecule 1,4-bis(phenylethynyl)-2,5-bis(ethoxy)benzene (PEEB) with Thiol (SH) terminal groups, contacted by Gold electrodes, has been investigated using Density functional Theory (DFT) and the Non-Equilibrium Green’s Function (NEGF) method. The results confirm the existence of a single-atom contact configuration with unusually high conductance for organic molecules of >0.1G₀.

Nodal diffusion codes such as DYN3D are used routinely for nuclear reactor simulations. These codes obtain homogenized few-group macroscopic reaction cross sections (XS) of coarse-mesh space elements (nodes) from XS-libraries, which are generated using lattice neutron transport codes. The libraries represent the dependence of homogenized XS on operational parameters such as fuel temperature, moderator density, moderator temperature, boron concentration and fuel burnup.

Typically, XS libraries are calculated using a branching procedure in which a 2D fuel assembly is first depleted to a certain burnup using core average operating conditions. Then, the branching calculations are performed at predetermined burnup points for all expected combinations of operating conditions. However, the local operating conditions (moderator density, fuel temperature, control rod presence etc.) in the core nodes may differ significantly from the core average conditions. Therefore, XS generation using a single assembly depletion calculation under core averaged conditions neglects the local variations of the spectrum history and may lead to errors in the XS. In order to account for the local spectrum history effects, a new XS correction method was recently developed and implemented in DYN3D. The method utilizes the local Pu-239 concentration as an indicator of spectral history. Pu-correction was verified in a wide range of spectral conditions. However, it is not able to reproduce fuel reactivity changes due to outage periods.

This paper presents a new hybrid method developed and implemented in DYN3D, which utilizes advantages of both, the micro-depletion correction and Pu-correction. The macroscopic XS are corrected using local concentrations of the most neutronically important nuclides, which are calculated by DYN3D using fast and accurate CRAM method. The isotopic microscopic cross sections and macroscopic transport and scattering XS are corrected applying Pu-correction methodology. General applicability of the proposed method is demonstrated on various fuel types and spectral condition, including BWR and PWR unit cells with UOX and MOX fuel.

Polycrystalline alumina samples (α-Al₂O₃, purity: 99.8%) were irradiated by ⁶³Cu heavy ions (E = 0.5 MeV/u) at various fluences. After irradiation, absorption measurements were performed within the wavelength range from 200 to 1000 nm to evaluate color center evolution. Thermal annealing behavior of the created defects was investigated with respect to annealing temperature and duration. Complex color center formation processes depending on particle fluence and temperature could be observed. Calculated activation energies necessary for F- and F+-center migration are ∼0.3 eV for temperatures ranging from RT to ∼673 K.

Die vorliegende Arbeit beschäftigt sich mit der quantitativen Bestimmung von Gasphasenverteilungen in industriellen Kreiselpumpen unter Verwendung der hoch auflösenden Gammastrahlentomographie. Die Messgenauigkeit des Tomographiesystems wurde mit einem rotierenden, modularen Messphantom bestimmt, welches entwickelt wurde um verschiedene Gasgehalte und Strukturen nachzubilden. Mit definierten Konfigurationen dieses Phantoms wurde erstmals eine kombinierte Methode zur Aufnahme der Tomographiedaten durchgeführt und validiert. Die anschließenden Untersuchungen einer Kreiselpumpe bei verschiedenen eingespeisten Gasgehalten zeigten einen Einfluss der Eintrittsbedingungen auf die Gasverteilung im Laufrad und somit auf das Betriebsverhalten.

This thesis presents the quantitative determination of gas-phase distributions in an industrial centrifugal pump using high-resolution gamma-ray computed tomography. Measurement accuracy was determined onto a sophisticated and rotated modular test mockup miming various gas fraction distributions and structures. Additionally, combined CT scanning mode was applied for the first time and validated using defined mockup configuration. Furthermore, investigations of the centrifugal pump operated with various gas fractions at the inlet showed a non-negligible influence of the inlet conditions onto the gas-phase distribution inside the impeller wheel and thus the operational behavior.

In this work we have studied how gas accumulates in an industrial centrifugal pump under various steady-state two-phase flow conditions. Thereby we considered both horizontal and vertical pump installation positions. Phase fractions within the impeller region of the pump have been quantitatively disclosed using high-resolution gamma-ray computed tomography (HireCT) and applying time-averaged rotation-synchronized CT scanning technique. The study was made for inlet volumetric gas flow rates between 0 % and 5 %. To account for different inlet flow conditions, which are assumed to occur during unwanted gas entrainment by hollow vortices we produced disperse and swirling gas-liquid inlet flow. In this way, the influence of inlet flow boundary conditions on the pump performance as well as gas fraction distributions and gas holdup within the impeller wheel region could be successfully analysed and compared with respect to the impeller alignment. In addition, for the first time, thin gas films at the pressure side of the impeller wheel blades could be visualized in an industrial centrifugal pump.

Many physically realistic problems can be described in terms of parameter-dependent eigenvalue problems of some non-Hermitian operators, as scattering problems or as dynamical flow problems. A common feature of such problems is the existence of degenerate configurations which can be associated to dynamical bifurcation behavior, spectral branch points or special types of singularities in the scattering matrix. Mathematically, such problems are related to non-diagonalizable spectral operator decompositions (the existence of non-trivial Jordan blocks), multiple eigenvalues and the coalescence of singularities in vector flow fields. In parameter spaces these configurations show up as so called discriminant varieties well known from algebraic geometry and singularity theory. In the talk, the structural interrelation of these effects is demonstrated and illustrated on concrete problems from PT quantum mechanics, optical lasing systems and the Bloch-sphere representation of simple time-dependent quantum mechanical problems.

The dynamics of nondissipative and dissipative autonomous Bose-Hubbard dimers is considered in second-order polynomial approximation as flow dynamics on the Bloch sphere. Special emphasis is laid on the stationary-point and singularity structure of the flows, related underlying algebraic stability features encoded in 10th-order homogeneous polynomials describing algebraic discriminant varieties over 3-dimensional projective parameter spaces. Reduced resolvent techniques, hidden Jordan block structures and relations to singularity theory provide further insights into the dynamics and possibly existing limit cycles.

This paper presents the upgraded `In situ growth of Nanoscructures on Surfaces' (INS) endstation of the InterFace beamline IF-BM32 at the European Synchrotron Radiation Facility (ESRF). This instrument, originally designed to investigate the structure of clean surfaces/interfaces/thin-films by surface X-ray diffraction, has been further developed to investigate the formation and evolution of nanostructures by combining small- and wide-angle X-ray scattering methodologies, i.e. grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence X-ray diffraction (GIXD). It consists of a UHV chamber mounted on a z-axis type goniometer, equipped with residual gas analysis, reflection high-energy electron diffraction (RHEED) and Auger electron spectroscopy (AES) to complete the X-ray scattering investigations. The chamber has been developed so as up to eight sources of molecular beam epitaxy (MBE) can be simultaneously mounted to elaborate the nanostructures. A chemical vapor deposition (CVD) set-up has been added to expand the range of growing possibilities, in particular to investigate in situ the growth of semiconductor nanowires. This setup is presented in some detail, as well as the first in situ X-ray scattering measurements during the growth of silicon nanowires.

Combining semiconducting and ferromagnetic properties, ferromagnetic semiconductors have been under intensive investigation for more than two decades. Mn doped III-V compound semiconductors have been regarded as the prototype of ferromagnetic semiconductors from both experimental and theoretic investigations. The magnetic properties of III-V:Mn can be controlled by manipulating free carriers via electrical gating, as for controlling the electrical properties in conventional semiconductors. However, the preparation of ferromagnetic semiconductors presents a big challenge due to the low solubility of Mn in semiconductors. Ion implantation has been developed as a standard method for doping Si in microelectronic industry. In this talk, I will show how ion beams can be used in fabricating and understanding ferromagnetic semiconductors. First, ion implantation followed by pulsed laser melting (II-PLM) provides an alternative to the widely used low-temperature molecular beam epitaxy (LTMBE) approach [1-6]. Both ion implantation and pulsed-laser melting occur far enough from thermodynamic equilibrium conditions. Ion implantation introduces enough dopants and the subsequent laser pulse deposit energy in the near-surface region to drive a rapid liquid-phase epitaxial growth. Going beyond LT-MBE, II-PLM is successful to bring two new members, GaMnP and InMnP, into the family of III-V:Mn. Both GaMnP and InMnP films show the signature of ferromagnetic semiconductors and an insulating behavior. Second, we use helium ion to precisely compensate hole in ferromagnetic semiconductors while keeping the Mn concentration constant [7-9]. By this approach, one can tune the magnetic properties of ferromagnetic semiconductor as well as pattern a lateral structure. It also provides a route to understand how carrier-mediated ferromagnetism is influenced by localization.

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[3] S. Zhou, et al., Appl. Phys. Express 5, 093007 (2012).
[4] M. Khalid et al., Phys. Rev. B 89, 121301(R) (2014).
[5] Y. Yuan, et al, IEEE Trans. Magn. 50, 2401304 (2014).
[6] Y. Yuan, et al. J. Phys. D: Appl. Phys. in press (2015).
[7] Lin Li, et al., J. Phys. D: Appl. Phys. 44 099501 (2011).
[8] Lin Li, et al., Nucl. Instr. Meth. B, 269, 2469-2473 (2011).
[9] S. Zhou, et al. Phys. Rev. B, in revision (2015).

In relation to satellite applications like global navigation satellite systems (GNSS) and remote sensing, the electron density distribution of the ionosphere has significant influence on trans-ionospheric radio signal propagation. In this paper, we develop a novel ionospheric tomography approach providing the estimation of the electron density's spatial covariance and based on a best linear unbiased estimator of the 3-D electron density. Therefore a non-stationary and anisotropic covariance model is set up and its parameters are determined within a maximum-likelihood approach incorporating GNSS total electron content measurements and the NeQuick model as background. As a first assessment this 3-D simple kriging approach is applied to a part of Europe. We illustrate the estimated covariance model revealing the different correlation lengths in latitude and longitude direction and its non-stationarity. Furthermore, we show promising improvements of the reconstructed electron densities compared to the background model through the validation of the ionosondes Rome, Italy (RO041), and Dourbes, Belgium (DB049), with electron density profiles for 1 day. © Author(s) 2015.

Uranium-americium mixed oxides are potential compounds to reduce americium inventory in nuclear waste via a partitioning and transmutation strategy. A thorough assessment of the oxygen-to-metal ratio is paramount in such materials as it determines the important underlying electronic structure and phase relations, affecting both thermal conductivity of the material and its interaction with the cladding and coolant. In 2011, various XAS experiments on U1(-x)Am(x)O(2 +/-delta) a samples prepared by different synthesis methods have reported contradictory results on the charge distribution of U and Am. This work alleviates this discrepancy. The XAS results confirm that, independently of the synthesis process, the reductive sintering of U1-xAmxO2 +/-delta leads to the formation of similar fluorite solid solution indicating the presence of Am+III and U+V in equimolar proportions.

Certain binary alloys exhibit magnetic properties which heavily depend on their structural order/disorder. For example FeAl is paramagnetic in the chemically ordered B2-phase whereas it shows ferromagnetic behavior if the chemically disordered A2-phase is investigated. We will demonstrate that by means of ion irradiation a phase transition from the chemically ordered to the chemically disordered phase can easily be achieved and that temperature treatment leads to the reverse phase transition.
One of the major advantages of ion irradiation is the fact that the interaction is extremely local and hence nanoscale disorder features can directly be written into an ordered environment. This technology is used to create nanoscale ferromagnetic features in a paramagnetic matrix. The achievable magnetic patterning resolution is determined and the magnetic domains as well as stray fields arising from the nanomagnets are imaged.

Reference:

R. Bali et al., Nano Lett. 14, 435 (2014).

We report low-temperature de Haas–van Alphen (dHvA) effect measurements in magnetic fields up to 35 T of the heavy-fermion superconductor Ce₂PdIn₈. The comparison of the experimental results with band-structure calculations implies that the 4f electrons are itinerant rather than localized. The cyclotron masses estimated at high field are only moderately enhanced, 8m₀ and 14m₀, but are substantially larger than the corresponding band masses. The observed angular dependence of the dHvA frequencies suggests quasi-two-dimensional Fermi surfaces in agreement with band-structure calculations. However, the deviation from ideal two-dimensionality is larger than in CeCoIn₅, to which Ce₂PdIn₈ bears a lot of similarities. This subtle distinction accounts for the different superconducting critical temperatures of the two compounds.

The ex-situ qualitative study of the kinetic formation of the poly-oxo cluster U38, has been investigated after the solvothermal reaction. The resulting products have been characterized by means of powder XRD and scanning electron microscopy (SEM) for the solid phase and UV/Vis, X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and NMR spectroscopies for the supernatant liquid phase. The analysis of the different synthesis batches, stopped at different reaction times, revealed the formation of spherical crystallites of UO2 from t= 3 h, after the formation of unknown solid phases at an early stage. The crystallization of U38 occurred from t=4 h at the expense of UO2, and is completed after t=8 h. Starting from pure uranium(IV) species in solution (t=0–1 h), oxidation reactions are observed with a UIV/UVI ratio of 70:30 for t=1– 3 h. Then, the ratio is inversed with a UIV/UVI ratio of 25/75, when the precipitation of UO2 occurs. Thorough SEM observations of the U38 crystallites showed that the UO2 aggregates are embedded within. This may indicate that UO2 acts as reservoir of uranium(IV), for the formation of U38, stabilized by benzoate and THF ligands. During the early stages of the U38 crystallization, a transient crystallized phase appeared at t=4 h. Its crystal structure revealed a new dodecanuclear moiety (U12), based on the inner hexanuclear core of {U6O8} type, decorated by three additional pairs of dinuclear U2 units. The U12 motif is stabilized by benzoate, oxalates, and glycolate ligands.