Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

We investigated lasing performance of a two-slab Yb:QX glass, a two and a four-slab Yb:YAG laser amplifier which were facet-cooled. As coolant di-Deuterium Oxyde (D2O) flowed between the active slabs while the pump and the laser light were passing through the very low absorbing heavy-water films. A square pump profile with a maximum intensity of 40 kW/cm2 drove the amplifier with a peak fluence of 5.5 J/cm2 at a pulse duration of 6 ns. We demonstrated a maximum pulse energy of 1 J for each gain medium as well as a repetition rate of 10 Hz for Yb:YAG and 1Hz for Yb:QX glass.

Mineral potential mapping aims at defining target zones of future local mineral exploration efforts on the basis of regional geochemical and geological surveys. Geochemical potential mapping typically involves using a small set of elements to predict an anomalous presence of a mineral commodity related with them. In this context it is common to work with logarithmically transformed concentrations of elements. This contribution explores a compositionally compliant approach to potential mapping using geochemical evidences, in which the whole set of components is applied a log-ratio transformation before any potential mapping technique is used. In this way, candidate zones can be identified by its high value in a certain ratio of elements, implying that the important information is a contrast betweeen two or more elements, and not an absolute concentration of one of them. Two different potential mapping techniques are used (a method equivalent to the Fisher rule, and a hierarchical binary logistic regression, both accounting for spatial dependence), with equivalent results.

The interaction of differential rotation and toroidal fields that are current-free in the gap between two corotating axially unbounded cylinders is considered. It is shown that non-axisymmetric perturbations are unstable if the rotation rate and Alfven frequency of the field are of the same order, almost independent of the magnetic Prandtl number Pm. For the very steep rotation law Omega proportional to R^2 (the Rayleigh limit) and for small Pm, the threshold values of rotation and field for this azimuthal magnetorotational instability (AMRI) scale with the ordinary Reynolds number and the Hartmann number, respectively. A laboratory experiment with liquid metals like sodium or gallium in a Taylor-Couette container has been designed on the basis of this finding. For fluids with more flat rotation laws, the Reynolds number and the Hartmann number are no longer typical quantities for the instability. For the weakly non-linear system, the numerical values of the kinetic energy and the magnetic energy are derived for magnetic Prandtl numbers <= 1. We find that the magnetic energy grows monotonically with the magnetic Reynolds number Rm, while the kinetic energy grows with Rm/root Pm. The resulting turbulent Schmidt number, as the ratio of the 'eddy' viscosity and the diffusion coefficient of a passive scalar (such as lithium), is of the order of 20 for Pm = 1, but for small Pm it drops to the order of unity. Hence, in a stellar core with fossil fields and steep rotation law, the transport of angular momentum by AMRI is always accompanied by an intense mixing of the plasma, until the rotation becomes rigid.

The prediction of bubbles size distributions in bubble columns reactors is a great challenge in design and optimization of operating conditions. The implementation of Population Balance Equations (PBE) for bubbly flows into CFD codes allowed better understanding of the hydrodynamic behavior of bubble columns and better quantification of the interfacial area for the estimation of interphase transport phenomena. On the other hand, the complexity of numerical models increased with the introduction of new sub-models for the determination of Bubble Size Distributions (BSD). The formulation of sink and source terms of such PBE is a very controversial issue. These terms depend on assumption on the dominating mechanisms due to turbulence, buoyancy, wake, shear, etc.. However, the unknown physical effects, the variety of constants of Breakup and Coalescence (B&C) kernels as well as their complex coupling with the hydrodynamics of the flow prevent to generalize existing models.
In this work, a new approach will be presented to determine B&C rates in bubble columns using experimental BSD data and hydrodynamic characteristics such as phase fractions at several column heights e.g. obtained by ultrafast X-ray tomography. To calculate the experimental B&C rates, a set of non-linear PBE is solved at each scanning height with the measured hydrodynamic data and statistical equations to consider diameter effect of coalescing bubbles.
The approach was applied to own experimental data and data from literature. Good agreement was found for the numerical simulated BSD and hydrodynamics based on the derived B&C rates compared to experimental data.
For future work, this approach allows to directly validate existing B&C models with different gas and liquid physical properties and operating conditions in order to formulate more generalized B&C models for their implementation in CFD models.

Anisotropic nanoparticle (NP) arrays with useful optical properties, such as localized plasmon resonances (LPRs), can be grown by self-assembly on substrates, but these systems often have significant dispersion in NP dimensions and distribution, which makes a numerical approach to modeling the LPRs very difficult. An improved analytic approach to this problem is discussed in detail and applied successfully to NP arrays from three systems that differ in NP metal, shape and distribution, and in substrate and capping layer. The materials and anisotropic NP structures that will produce LPRs in desired spectral regions can be determined using this approach.

Besides natural the occurring actinides uranium and thorium the most impact of higher actinides in biological systems is connected to the release of transuranium elements in nuclear accidents as Chernobyl and Fukushima and from scenarios which are seen in the discussion of radioactive waste storage.
In radioactive waste storage sites in the deep underground, however, the first organism which may have contact to actinides are microorganism. In later transport to the earth surface these radionuclides may also access the food chain via several ways of uptake. One of these ways may occur by uptake of actinides by plants.
Nevertheless, the uptake depends on the bioavailability of these elements and therefore also on the speciation or binding form before and after uptake.

It can be stated already here, that some of these radionuclides are much less studied than others. This may be caused by the difficult handling of the radioelements, as they are α-emitting radionuclides and therefore special equipment in the laboratories is necessary as well as regulations of radiation protection have to be considered.

An introduction in the uptake of radionuclides by plants has been given by M. Greger. Besides the description of common uptake mechanisms only few information about actinides is given.
An overview about soil to plant transfer is given by D. Robertson et al. The factors vary very strong depending on plant species, soil and experimental conditions, but compared to Sr isotopes the values for actinides are smaller.

Imaging of brain α4β2 nicotinic acetylcholine receptors (nAChRs), a subtype involved in learning and memory processes, can potentially help to predict prognosis of dementia in neurodegenerative disorders like Alzheimer´s disease (AD). Two [¹⁸F]flubatine enantiomers [¹⁸F]-1 (derivatives of homoepibatidine) are promising radiotracers for neuroimaging of α4β2-nAChRs [1] and are currently investigated in clinical studies. Therefore, their metabolism was investigated by two different approaches. Initially, (+)- and (−)-1, were incubated with liver microsomes from mouse or human to produce phase I metabolites. After precipitation with acetonitrile, LC-MS/MS studies of the supernatants were performed to compare metabolic stabilities and for structural elucidation of metabolites. Thereafter, (+)-[¹⁸F]-1 (~280 MBq) was injected into mice. Liver, plasma and urine samples were taken, precipitated and investigated by radio-HPLC. In order to conclude about chemical identities of the radiometabolites of (+)-[¹⁸F]-1, we applied identical chromatographic conditions to both LC-MS and radio-HPLC. LC-MS revealed that both flubatine enantiomers retained a high level of metabolic stability. Furthermore, they were metabolized to higher extent by mouse than by human microsomes. In direct comparison, (+)-1 proved to be more stable than (−)-1. A series of metabolites resulting from oxidation was detected (M0-M6). Presence of each metabolite was species and enantiomer dependent. MS/MS examinations revealed the azabicyclic ring system being exclusively affected by oxidation, namely C- and N-hydroxylation. Using 3-hydroxy flubatine as reference, we identified the radiolabelled derivative (Mc) as one of the metabolites. Correlation with radio-HPLC supports the existence of further radiometabolites resulting from oxidation beside others (Fig. 1). We conclude, that our combined approach offers a useful tool for assignment and finally identification of radiotracer metabolites.

[1] Brust, P. et al. Preclinical Aspects of Nicotinic Acetylcholine Receptor Imaging. In PET and SPECT of Neurobiological Systems; Dierckx, R. A.; Otte, A.; Vries, E. F. de; van Waarde, A.; Luiten, P. G., Eds.; Springer Berlin Heidelberg, 2014; pp 465-512.

Rapid development of PET and the design of larger targets cause a greater need of oxygen-18 enriched water as target material for fluorine-18 production and entail increased costs for oxygen-18 enriched water. This forced us to consider its re-use for research purposes. Used O-18 water is mainly contaminated with metal radionuclides, non-radioactive salts and organic solvents. Here, we present (i) two methods for the removal of organic contaminants, (ii) analytical methods for quality assessment and (iii) findings for irradiation and radiosyntheses using activity produced from re-cycled water. Samples of used target water (1 L containing 44 mg L>sup-1 acetone and 396 mg L>sup-1 ethanol) were treated with UV irradiation (254 nm) [1] or with KMnO₄/NaOH at 50°C to reduce the concentration of these contaminants below 50 mg L>sup-1, respectively. Both methods allowed close-to-zero decrease of acetone and decrease of ethanol to 23 ± 20 mg L>sup-1 (n = 8). After vacuum distillation pure re-cycled water was obtained as proven by gamma spectrometry, gas chromatography, ICP-OES, and ion chromatography. Loss of O-18 enrichment (83%, pycnometry) was not observed. A reference study on O-16 water, contaminated by addition of 150 to 200 mg L>sup-1 methanol, ethanol, acetone and acetonitrile, showed a comparable oxidation potential of both methods for methanol, ethanol and acetone (decrease within 48 h below 50 mg L>sup-1). Oxidation of acetonitrile was only achieved with the UV-lamp within 7 days. Re-cycled water and virgin water (Hyox 18 Enriched Water), partly diluted to 83% O-18 enrichment, were irradiated in the Nirtra^® Fluor L-target at a CYCLONE 18/9 (iba) with 35 µA and 11.7 µAh. Comparison of produced activities of F-18, N-13 and metal radionuclides confirmed the high quality of the re-cycled water. Compared to undiluted virgin water a loss of the production yield of ~19% was observed. No significant influence on the radionuclide purity or radiochemical reactivity was detected. F-18 obtained from virgin water or re-cycled water irradiation was comparably used for radiosyntheses. Results of automated radiosyntheses (TRACERLAB™ FX-FN) of our new α4β2 nicotinic receptor ligand [¹⁸F]flubatine (n=5) and σ₁ receptor ligand [¹⁸F]fluspidine (n=8) as well as radiosyntheses for development of the α7 nicotinic receptor ligand [¹⁸F]NS14490 and ¹⁸F-labelled CB₂-selective N-aryl-oxdiazolyl-propionamides revealed equivalent yields and unchanged product qualities. The described purification procedures enable a multiple re-cycling of target water for successful F-18 production and application for research purposes with reasonable production yields and efficient economical use of the target water.

[1] DE 29504388 U1, 1995

The long-term disposal of high-level nuclear waste in deep geological formations is discussed worldwide as main strategy for nuclear waste management. In addition to salt and crystalline rock, argillaceous rock has been proposed as potential host rock and backfill material for nuclear waste repositories. This is due to favorable characteristics of clay minerals such as their swelling properties and their large surface areas leading to a low permeability and high retention efficiency toward radionuclides. Sorption and diffusion of safety relevant radionuclides on/in clay rock are important physicochemical processes that have to be studied to contribute to a reliable long-term safety assessment for future nuclear waste repositories.

Clay rock is closely associated with natural organic matter. Low molecular weight organic acids such as acetate, lactate, propionate and formate as well as fulvic and humic acid-like substances can be released from the clay under certain conditions [1]. These organics can influence the migration of radionuclides in the environment by forming soluble complexes or stable colloids. In addition, for the disposal of high-level nuclear waste in clay formations, elevated temperatures of up to 100 °C are expected close to the waste containers resulting from the radioactive decay of the stored radionuclides. Besides that, pore waters of North German clay deposits, considered for underground nuclear waste repositories, show relatively high salinities (2 to 3.5 M). Thus, effects of organic matter, temperature and salinity have to be taken into account for a reliable prediction of radionuclide migration in the geosphere.

Batch sorption studies with clay minerals revealed that the U(VI) sorption onto kaolinite [2] is much higher than the Np(V) sorption [3] in 0.1 M NaClO4. In the presence of humic acid, the actinide sorption is increased in the acidic pH range and decreased in the near-neutral pH range. The influence of ionic strength was studied for U(VI) sorption onto montmorillonite by applying 0.1 to 3 M NaCl and CaCl2 as background electrolytes. It was observed that the ionic strength effect on U(VI) sorption on montmorillonite is very small. In NaCl, a decrease of U(VI) sorption with ionic strength is only observed below pH 6 and up to an ionic strength of 2 M. In CaCl2, U(VI) sorption is at least partly governed by secondary phase formation.

The retention behavior of the natural clay rock Opalinus Clay (Mont Terri, Switzerland) toward U(VI) was studied by means of batch sorption and diffusion experiments. Opalinus Clay is considered as representative host rock of a potential nuclear waste repository in argillaceous rock. For the U(VI) sorption onto Opalinus Clay in synthetic Opalinus Clay pore water (pH = 7.6, I = 0.36 M) at 25 °C, the distribution coefficient, Kd, was determined with 22.2 ± 0.4 L/kg [4]. This shows that the U(VI) sorption is relatively weak under pore water conditions. It is comparable to the Np(V) sorption onto Opalinus Clay (25 ± 5 L/kg [5]). This can be attributed to the predominance of the weakly sorbing Ca2UO2(CO3)3(aq) complex in the Opalinus Clay pore water.

The U(VI) sorption onto Opalinus Clay was also studied in 0.1 M NaClO4 in the pH range 3 to 10. Results of surface complexation modelling [6], applied for blind prediction of pH-dependent U(VI) sorption onto Opalinus Clay, showed that U(VI) may predominantly sorb onto illite and montmorillonite. In addition, U(VI) sorption onto Fe(III) minerals was predicted. U(VI) sorption onto further minerals of the clay (kaolinite, chlorite, quartz, feldspars) is negligible.

With increasing concentration of low molecular weight organic acids (10-5 to 10-2 M), the U(VI) sorption onto Opalinus Clay in pore water decreases due to complex formation in solution. The mobilizing effect of the organics on U(VI) increases in the following sequence: formate < lactate ~ acetate ≤ propionate < tartrate < citrate. In the presence of 1×10-2 M citrate, which has been identified as important ligand in radioactive waste problems, the Kd value for U(VI) amounts to only (1.1 ± 0.3) L/kg. The influence of the organic ligands on the U(VI) sorption onto Opalinus Clay correlates with the stability of the respective U(VI) complexes. In contrast, humic acid (≤ 50 mg/L) does not affect U(VI) sorption [4]. With increasing temperature up to 60 °C, the U(VI) sorption increases both in the absence and in the presence of clay organics.

The U(VI) diffusion in compacted Opalinus Clay was studied in the absence and presence of humic acid at 25 and 60 °C under anaerobic conditions using Opalinus Clay pore water [7]. The effective diffusion and distribution coefficients (De and Kd) determined for U(VI) and humic acid at 25 and 60 °C show that humic acid has no significant influence on the U(VI) diffusion. The diffusion profiles obtained for humic acid in Opalinus Clay at 25 and 60 °C show contributions of at least two different humic acid particle size fractions (< 1 kDa and 10−100 kDa). The smaller humic acid fraction diffused through the whole clay samples at both temperatures within three months whereas the larger humic acid fraction diffused only about 500 µm into the clay. This shows the filtration effect of the compacted clay and also a different sorption affinity of the humic acid size fractions toward Opalinus Clay. At 60 °C, the diffusion profiles of two U(VI) species were observed, which were attributed to a colloidal and an aquatic U(VI) species. The De and Kd value of the aquatic U(VI) species increased with increasing temperature. However, these changes compensated each other, thus, an increase of the temperature to 60 °C did not accelerate the migration of U(VI) through Opalinus Clay.

Under environmentally relevant conditions (pH > 7), U(VI) is only weakly sorbed by the natural clay rock Opalinus Clay. However, since molecular diffusion is the decisive retardation process in clay rock, Opalinus Clay has a good retention potential toward U(VI).

[1] Courdouan, A. et al. (2007) Appl. Geochem. 22, 2926-2939.
[2] Křepelová, A. et al. (2006) Radiochim. Acta 94, 825-833.
[3] Schmeide, K. and Bernhard, G. (2010) Appl. Geochem. 25, 1238-1247.
[4] Joseph, C. et al. (2011) Chem. Geology 284, 240-250.
[5] Wu, T. et al. (2009) Environ. Sci. Technol. 43, 6567-6571.
[6] Joseph, C. et al. (2013) Appl. Geochem. 36, 104-117.
[7] Joseph, C. et al. (2013) Geochim. Cosmochim. Acta 109, 74-89.

Molecular electronics has been a field of big interest for the last years. Using the technique of mechanically controllable break junctions we characterize different organic molecules, e.g. 1,4-Diethoxy-2,5-bis(4-sulfanyl-phenylethynyl)-benzene (PEEB) and switchable molecular wires, dissolved in an organic non-polar solvent. IV-curves taken from the molecules connected to single gold atom contacts show the expected tunneling behavior described by the single-level model: weak coupling of the molecules to the gold atoms implies an off-resonant tunneling process and a transport through a single channel. Varying the end-groups of the molecules leads to a different transport behavior. Figure 1 shows a 2D histogram of IV-curves of PEEB with amino end-groups. Based on the single-level transport model the analysis of the current-voltage characteristics delivers the energy of the molecular level and the coupling between electrode and molecule. It also indicates a reliable contact of the molecules to the gold atoms. A further goal is the investigation of an electric gate effect on the transport behavior through the molecules.

Molecular electronics has been of big interest for the last years. To allow an electrical characterization of single molecules a reliable contact to gold atoms is required. We ensure this by using single organic molecules with a plain structure, in particular 1,4-Diethoxy-2,5-bis (4-sulfanyl-phenylethynyl)-benzene and single stranded DNA fragments, dissolved in an organic non-polar solvent. For measurements we use the technique of mechanically controllable break junctions. IV-curves taken from single molecules connected to single gold atom contacts show the expected tunneling behavior, from which we gain the energy of the molecular level and the coupling between electrode and molecule.

Spin-1/2 Heisenberg antiferromagnets Cs₂CuCl₄ and Cs₂CuBr₄ with distorted triangular-lattice structures are studied by means of electron spin resonance spectroscopy in magnetic fields up to the saturation field and above. In the magnetically saturated phase, quantum fluctuations are fully suppressed, and the spin dynamics is defined by ordinary magnons. This allows us to accurately describe the magnetic excitation spectra in both materials and, using the harmonic spin-wave theory, to determine their Exchange parameters. The viability of the proposed method was proven by applying it to Cs₂CuCl₄, yielding J/k_B = 4.7(2) K, J'/k_B = 1.42(7) K, [J'/J ≃ 0.30] and revealing good agreement with inelastic neutronscattering results. For the isostructural Cs₂CuBr₄, we obtain J/k_B = 14.9(7) K, J'/k_B = 6.1(3) K, [J'/J ≃ 0.41], providing exact and conclusive information on the exchange couplings in this frustrated spin system.

Short Time Annealing on a microsecond to nanosecond scale presents new challenges to temperature measurement. Pyrometers are widely used owing to their commercial availability, short response time, easy handling and contactless operation. However, they hold a source for considerable measurement errors. False readings are easily gained producing large errors during temperature measurement.
This chapter intends to give the reader an overview on characteristic features associated with Radiation Thermometry in a broader sense and more specifically with Pyrometry.

The mineral separation process flotation is fundamentally relying on hydrophobic interactions, which are still not entirely understood and heavily discussed in literature. We introduce the various possibilities to determine hydrophobic properties of mineral surfaces in water using the concept of colloidal probe atomic force microscopy. We base our method on the most accepted theories of the hydrophobic effect of hydrophobic surfaces in water, which consider nanoscopic gas layers to be responsible for the long range interactions. Finally, we correlate the hydrophobic parameters with microflotation experiments for magnetite and quartz surfaces.

Low remanent magnetization as key prerequisite for the ability of helicity dependent all-optical magnetic switching (AOS) is demonstrated for an artificial zero moment magnet. A heterostructure consisting of two amorphous ferrimagnetic Tb36Fe64 and Tb19Fe81 alloy layers is designed to yield a zero remanent net magnetization at room temperature by means of an antiparallel interfacial exchange coupling of the dominant magnetic moments. The canceling layer magnetizations provide vanishing demagnetization fields and the ability of AOS. Contrary to this, no all-optical switching is observed for single Tb36Fe64 and Tb19Fe81 films. This study provides further evidence that the ability for all-optical magnetic switching is correlated to the remanent sample magnetization and thus to the difference in magnetic moment of the rare-earth and transition-metal sublattices.

We have recently described a novel modular targeting platform for T cell recruitment that not only efficiently replaces but also is superior to conventional T cell-engaging bispecific antibodies as it allows for the flexible targeting of several antigens and the delivery of co-stimulatory ligands to malignant lesions, thereby enhancing the antitumor potential of redirected T cells.

The unique properties of SOI wafers enable the integration of heterogeneous materials with distinct functionalities in different layers. In particular, III-V compound semiconductors are very attractive for low-noise and high-speed electronic and photonic components integrated on a single chip. We have developed a CMOS compatible and fully integrated solution for the integration of III-V compound semiconductors with silicon technology for optoelectronic applications. InAs compound semiconductor nanostructures are synthesized in SOI wafers using the combined ion beam implantation and millisecond liquid-phase epitaxial growth. Optoelectronic and microstructural investigations carried out on implanted, annealed and selectively etched samples confirm the formation of high-quality III-V compound semiconductor nanostructures.

Excited magnetization dynamics in a spin-valve device consisting of an in-plane polarizer and an out-of-plane free layer were studied numerically. In the case where the free layer is assumed to lack any in-plane anisotropy components, a finite external field is required to generate steady-state dynamics, in agreement with previous reports. We demonstrate that this constraint can be removed and precession can be stabilized in zero applied field by introducing an additional in-plane anisotropy axis. Moreover, the in-plane anisotropy offers an additional degree of freedom for tuning the frequency response of the device.

Vortrag im Rahmen des IRE STATUS-SEMINAR 2013 „Nuclear Safety Research – From Reactors to Disposal“ 11. - 13.12.2013 in Dresden
Präsentation von Ergebnissen aus den Projekten NanoTrack und QNano

D mesons serve as excellent probes of hot and/or dense strongly interacting matter. They can provide insight into the restoration of chiral symmetry. The chiral condensate as well as other chirally odd condensates, such as certain four-quark condensates, are linked to order parameters of spontaneous chiral symmetry breaking. Thus, the evaluation of these higher order condensate contributions in the framework of QCD sum rules is of high interest. We present a general method for projecting Lorentz indices of ground state expectation values providing a crucial step towards a comprehensive calculation of higher order corrections to the operator product expansion of hadrons, especially D mesons, in a strongly interacting medium.

Summary
Quantitative positron emission tomography (PET) requires accurate scanner calibration, which is commonly performed using phantoms. It is not clear to what extent this procedure ensures quantitatively correct results in vivo, since certain conditions differ between phantom and patient scans.
Aim: We, therefore, have evaluated the actual quantification accuracy in vivo of PET under clinical routine conditions.
Patients, methods: We determined the activity concentration in the bladder in patients undergoing routine [¹⁸F]FDG whole body investigations with three different PET scanners (Siemens ECAT EXACT HR⁺ PET: n = 21; Siemens Biograph 16 PET/CT: n = 16; Philips Gemini-TF PET/CT: n = 19). Urine samples were collected immediately after scan. Activity concentration in the samples was determined in well counters cross-calibrated against the respective scanner. The PET (bladder) to well counter (urine sample) activity concentration ratio was determined.
Results: Activity concentration in the bladder (PET) was systematically lower than in the urine samples (well counter). The patient-averaged PET to well counter ratios for the investigated scanners are (mean ± SEM): 0.881 ± 0.015 (ECAT HR⁺), 0.898 ± 0.024 (Biograph 16), 0.932 ± 0.024 (Gemini-TF). These values correspond to underestimates by PET of 11.9%, 10.2%, and 6.8%, respectively.
Conclusions: The investigated PET systems consistently underestimate activity concentration in the bladder. The comparison of urine samples with PET scans of the bladder is a straightforward means for in vivo evaluation of the expectable quantification accuracy. The method might be interesting for multi-center trials, for additional quality assurance in PET and for investigation of PET/MR systems for which clear proof of sufficient quantitative accuracy in vivo is still missing.

Zusammenfassung
Für die Bestimmung quantitativer Parameter mittels Positronenemissionstomo graphie (PET) ist eine genaue Kalibrierung des PET-Scanners mit Hilfe geeigneter Phantommessungen notwendig. Auf Grund der offensichtlichen Unterschiede zwischen Phantom- und Patientenmessungen bestehen jedoch Unsicherheiten im Bezug auf die In- vivo- Genauigkeit einer solchen phantom-basierten Kalibrierung. Ziel dieser Studie war es daher die Genauigkeit
einer solchen Kalibrierung mittels klinischer Routinemessungen in vivo zu evaluieren.
Patienten, Methoden: Wir bestimmten die Aktivitätskonzentration in der Blase bei Patienten die an unterschiedlichen PET-Scannern eine [¹⁸F]FDG-Ganzkörperuntersuchung erhielten (Siemens ECAT EXACT HR⁺ PET: n = 21; Siemens Biograph 16 PET/CT: n = 16; Philips Gemini-TF PET/CT: n = 19). Unmittelbar nach Messung der Blasenregion gaben alle Patienten Urinproben ab. Die Aktivitätskonzentration der Urinproben wurde mit Hilfe eines kreuzkalibrierten Bohrlochzählers bestimmt. Im Anschluss wurde das Verhältnis zwischen Aktivitätskonzentration PET (Blase) zu Bohrlochzähler (Urinprobe) berechnet.
Ergebnisse: Die Aktivitätskonzentration in der Blase (PET) war systematisch niedriger als die der Urinproben (Bohrlochzähler). Das über die jeweiligen Patienten gemittelte Verhältnis zwischen PET und Bohrlochzähler war für die untersuchten Scanner (Mittelwert ± SEM): 0,881 ± 0,015 (ECAT HR⁺), 0,898 ± 0,024 (Biograph 16), 0,932 ± 0,024 (Gemini-TF). Diese Werte entsprechen Unterschätzungen der Aktivitätskonzentration durch die PET von jeweils 11,9%, 10,2% und 6,8%.
Schlussfolgerungen: Die untersuchten PETSysteme unterschätzen die Aktivitätskonzentration in der Blase. Der direkte Vergleich von Urinproben und PET-Bildern der Blase stellt eine einfache Art der In-vivo-Evaluation der zu erwartenden Quantifizierungsgenauigkeit eines PET-Scanners dar. Die vorgestellte Methode kann für Multicenterstudien, für eine zusätzliche Qualitätssicherung in der PET sowie für eine Untersuchung von PET/MRSystemen
interessant sein, für die es hinsichtlich einer ausreichenden Quantifizierungsgenauigkeit in vivo noch keine belastbaren Zahlen gibt.

Membrane treatment can be used to selectively remove chemical species from effluents. However, speciation depends on different chemical factors such as inorganic and organic reaction partners, tem-perature, and pH, complicating a deeper understanding of underlying mechanisms. In this study the potential of membrane separation for selective uranium removal was assessed. Speciation for complex chemical conditions in two real water samples was determined independently by predictive speciation modelling, and direct measurement using cryo-TRLFS (time-resolved laser-induced fluorescence spectroscopy). Different nanofiltration membranes and reverse osmosis membranes were characterized for their potential rejection, and pure water flux. The best performing membrane was then employed in cross-flow experiments and reached retentions over 99 % and U/Na-selectivities of 200. Uranium retentions showed a low dependency on feed uranium speciation. Continuing research is necessary for an exact determination of separation mechanisms for each membrane.

In the process of elaboration and evaluation of severe accident management guidelines, the assessment of the accident management measures and procedures plays an important role. This paper investigates the early in-vessel phase accident progression of a hypothetical station blackout scenario for a generic VVER-1000 pressurized water reactor. The study focuses on the following accident management measures: primary side depressurization with passive safety systems injection, secondary side depressurization with passive feeding from the feedwater system, and a combination of the both procedures. The analyses have been done with the mechanistic computer code ATHLET. The simulations give in-depth analyses of the reactor system behaviour, assessment of the time margins till heating up of the reactor core and insights into physical phenomena which can influence the passive feeding procedures for cooling of the reactor core. The simulation results show that such accident management measures can significantly prolong the time till core degradation. Maximum delay for core heat up can be achieved by sequentially realization of the secondary and primary side bleed and feed strategies. Due to reversed heat transfer in the steam generators or caused by the depressurization itself a part of the injected water is evaporated. Evaporation or flashing in the feedwater system can lead to an intermittent water injection, thus reducing the effectiveness of the feeding procedure.

The talk will first emphasize the role of the Ion Beam Center as large scale facility within our research center. Recent results of ion-assisted growth of carbon:metal nanocomposite thin films will be shown in the second part. In the third part of the talk the concept and the current state of the setting up of the cluster tool at the Ion Beam Center will be presented. Examples for possible in situ experiments are given. They include the layer exchange in carbon: nickel double layers, the growth mechanism of carbon on metals at different temperatures, the thermal stability and graphitization of carbon: metal films, and the graphitization of carbon implanted in metals.

We present the analysis of the inclusive K⁰ production in p+p and p+Nb collisions measured with the HADES detector at a beam kinetic energy of 3.5 GeV. Data are compared to the GiBUU transport model. The data support the presence of a repulsive momentum-dependent kaon potential as predicted by the Chiral Perturbation Theory (ChPT). For the kaon at rest and at normal nuclear density, the ChPT potential amounts to 35 MeV. A detailed tuning of the kaon production cross sections implemented in the model has been carried out to reproduce the experimental data measured in p+p collisions. The uncertainties in the parameters of the model were examined with respect to the sensitivity of experimental results from p+Nb collisions to the in-medium kaon potential.

An exclusive analysis of the 4-body final states Λ+p+π +K⁰ and Σ⁰+p+π⁺+K⁰ measured with HADES for p+p collisions at a beam kinetic energy of 3.5 GeV is presented. The analysis uses various phase space variables, such as missing mass and invariant mass distributions, in the four particle event selection (p, π⁺, π⁺, π^-) to find cross sections of the different production channels, contributions of the intermediate resonances Δ⁺⁺ and Σ(1385)⁺ and corresponding angular distributions. A dominant resonant production is seen, where the reaction Λ+Δ⁺⁺+K⁰ has an about ten times higher cross section (29.45 ±0.08 ^+1.67 _-1.46 ±2.06 μb) than the analougous non-resonant reaction (2.57 ±0.02 ^+0.21 _-1.98 ±0.18 μb). A similiar result is obtained in the corresponding Σ 0 channels with 9.26 ±0.05 ^+1.41 _-0.31 ±0.65 μb in the resonant and 1.35 ±0.02 ^+0.10 _-1.35 ±0.09 μb in the non-resonant
reactions.

With the presented work we lay the foundation for ab-initio studies of contacted carbon nanotubes with both metal and metal--carbide leads. We Focus on applying the frozen phonon method on top density-functional-theory calculations for electronic the system. Here we show our ab-initio results on the elastic and electronic properties of Al4C3 and the metastable Ni3C.

Furthermore we present an alternative non-perturbative approach to calculating the quantum conductance in CNT/molecular junctions at finite temperature. Strictly employing the Born--Oppenheimer approximation, we aim to calculate the influence of phonons on the conductance of such a system by averaging over a representative sample drawn from snapshots of thermal fluctuation of the lattice.

The downscaling and stressor technology of Si based devices is extending the performance of the silicon channel to its limits. Further downsizing of CMOS devices below 16 nm will need to solve some of the practical limits caused by one of the integration issues, such as chip performance, cost of development and production, power dissipation, reliability, etc. One solution for the performance progress which can overcome the downsizing limit in silicon technology is the integration of different functional optoelectronic elements within one chip.
We have realized a compact, CMOS compatible and fully integrated solution for the integration of III-V compound semiconductors with silicon technology for optoelectronic applications. The III-V nanostructured semiconductors are synthesized in either silicon or SOI wafers using the combined ion implantation and millisecond flash lamp annealing (FLA) techniques [1]. The FLA appears to be the most suitable one for this purpose. The energy budget introduced to the sample during FLA is sufficient to recrystallize silicon amorphized during implantation and to form III-V nanocrystals (NCs). In this paper we will present research results of the microstructural, optical and electrical properties of III-V quantum dots (InAs, GaAs and InP) formed in silicon and on SOI wafers. The influence of the annealing conditions and the lattice mismatch between III-V semiconductors and silicon on the shape of the III-V quantum dots will be examined. The annealing is performed at temperatures by far exceeding the melting point of bulk compound semiconductors, which leads to the formation of III-V nanostructures due to liquid phase epitaxy and enhances the probability for the incorporation of silicon atoms into III-V NCs. Silicon atoms are commonly used as n-type dopants in most III-V semiconductors. Therefore, liquid phase processing leads to the formation of heavily n-type doped single crystalline III-V nanostructures on silicon. If we consider that the synthesized NCs are n-type, by using a p-type silicon substrate a heterojunction can be formed between the III-V NCs and p-type Si. Conventional selective etching has been used to form the n-III-V/p-Si heterojunction. Current-voltage measurements confirm the heterojunction diode formation between n-type III-V quantum dots and p-type Si. The main advantage of our method is its ability to be integrated into large-scale silicon technology, which also allows applying it to Si-based optoelectronic devices.

In this study highly filled nanoparticle-polymer-composites consisting of the polymer poly(methyl methacrylate) and magnetite nanoparticles are synthesized via the solution and spray drying method. The synthesis process is carried out for two different solvents, dichloromethane and ethyl acetate, and the resulting suspensions and composites are compared to each other. The preparation of the composites consists of the following steps: First the magnetite nanoparticles are precipitated in an aqueous phase. In the next step the nanoparticles are coated with ricinoleic acid for stabilization and are transferred to the organic solvent dichloromethane. In a rotating evaporator the solvent dichloromethane is exchanged with ethyl acetate. Finally, the nanoparticles in the respective solvent and dissolved polymer are mixed and spray dried.
The stability of the nanoparticle suspensions is characterized using thermogravimetric and photometric analyses. The specific surface of spray dried composites is determined via BET measurements and the distribution of the nanoparticles is assessed with BSE-SEM imaging and laser diffraction.
The stability of the nanoparticles is independent of the examined solvents. Both solvents provide a homogeneous distribution of nanoparticles in the composite at high filler concentrations.

This study explores a possibility of designing a high conversion (HC) Th-U233 core for current generation of Pressurized Water Reactors (PWRs). Increasing the conversion ratio in existing PWRs can potentially improve the utilization of natural resources, through the exploitation of vast thorium reserves and reduction in natural uranium demand.
HC can be achieved through the use of heterogeneous seed-blanket (SB) Th-U233 fuel assembly design, where the supercritical seed works as a neutron supplier, while the subcritical blanket acts as U233 breeder. One of the main challenges associated with the heterogeneous SB fuel assembly designs is significant power imbalance between the seed and blanket regions caused by the high concentration of fissile material in the seed region and consequently requiring a substantial reduction in the core average power density.
The main objectives of the current work are: 1) to design a high conversion SB Th-U233 fuel assembly which is directly retrofittable into existing PWRs without introducing significant modifications into the core and plant design; 2) to estimate the reasonably achievable core power density level at which reactor safety is not compromised by performing 3D coupled neutronic and thermal-hydraulic (T-H) analysis of a typical PWR core fully loaded with HC Th-U233 SB fuel.
Part II of the paper reports on the steady-state whole core analysis of 100% Th-U233 fueled PWR. The results of this study demonstrate the principal feasibility of operating a self-sustainable Th-U233 PWR core at power density of 60 W/cc in three-batch annual fuel cycle without exceeding the main safety limits.

This study explores a possibility of designing a high conversion (HC) Th-U233 core for current generation of Pressurized Water Reactors (PWRs). Increasing the conversion ratio in existing PWRs can potentially improve the utilization of natural resources, through the exploitation of vast thorium reserves and reduction in natural uranium demand.
HC can be achieved through the use of heterogeneous seed-blanket (SB) Th-U233 fuel assembly design where the supercritical seed works as a neutron supplier, while the subcritical blanket acts as U233 breeder. One of the main challenges associated with the heterogeneous SB fuel assembly designs is a significant power imbalance between the seed and blanket regions caused by the concentration of fissile material primarily in the seed zone and consequently requiring a substantial reduction in the core average power density.
The main objectives of the current work are: 1) to design a high conversion SB Th-U233 fuel assembly which is directly retrofittable into existing PWRs without introducing significant modifications into the core and plant design; 2) to estimate the reasonably achievable core power density level at which reactor safety is not compromised by performing 3D coupled neutronic and thermal-hydraulic (T-H) analysis of a typical PWR core fully loaded with HC Th-U233 SB fuel.
Part I of the paper presents the results of the assembly-level parametric study aiming at the selection of a number of SB fuel assembly configurations for the following whole-core analysis. The assembly configurations are selected according to their potential to satisfy the specified fuel cycle requirements and comply with the T-H safety limits.
The results of the 3D full core analysis are reported in Part II of the paper.

Membrane proteins fulfil vital functions in cellular signalling and ion exchange across cell membranes. Their function originates in well defined structural transitions of transmembrane and extramembraneous protein domains. The latter experience aqueous and hydrophobic solvation forces, respectively. We have used time-resolved FTIR spectroscopy coupled to static fluorescence measurements to study how this solvation balance at the membrane water interface affects membrane protein structure. Transmembrane peptides derived from rhodopsin, a prototypical G protein-coupled receptor (GPCRs), exhibit solvent-accessible stretches which couple protonation and hydration to local helical structure: protonation of a conserved cytosolic site in helix 3 (Glu-134) causes side chain partitioning at the water lipid interface [1]. Vice versa, the side chain charge affects structural transitions that are induced by transients (seconds) of interfacial water potential. These local processes depend on the hydrophobic context of the amino acid sequence. Opsin mutants containing amino acid replacements of the same carboxyl side chain also exhibit altered responses of their structure to water potential. The data indicate that the conserved carboxyl in helix 3 of GPCRs is a protonation-controlled hydration site that regulates the partial entry of water at the protein lipid interface, thereby contributing to the free enthalpy difference between active and inactive structures of the receptor.

Redox behavior of [UO₂(gha)DMSO]^−/0 couple (gha = glyoxal bis(2-hydroxanil)ate, DMSO = dimethyl sulfoxide) in DMSO solution was investigated by cyclic voltammetry and UV-vis-NIR spectroelectrochemical technique, as well as density functional theory (DFT) calculations. [UO₂(gha)DMSO]⁻ was found to be formed via one-electron reduction of UO₂(gha)DMSO without any successive reactions. The observed absorption spectrum of [UO₂(gha)DMSO]⁻, however, has clearly different characteristics from those of uranyl(V) complexes reported so far. Detailed analysis of molecular orbitals and spin density of the redox couple showed that the gha²⁻ ligand in UO₂(gha)DMSO is reduced to gha●³⁻ to give [UO₂(gha)DMSO]⁻ and the formal oxidation state of U remains unchanged from +6. In contrast, the additional DFT calculations confirmed that the redox reaction certainly occurs at the U center in other uranyl(V/VI) redox couples we found previously. The non-innocence of the Schiff base ligand in the [UO₂(gha)DMSO]^−/0 is due to the lower energy level of LUMO in this ligand relative to those of U 5f orbitals. This is the first example of the non-innocent ligand system in the coordination chemistry of uranyl(VI).

The present work deals with the multilayer resuspension of solid aerosol particles off a multilayer deposit exposed to a sudden gas flow increase. The heavy detachment of particles spans a wide range of industrial and non-industrial applications. It is used extensively in applications dealing with the resuspension of dust by wind, the resuspension of particles in ventilation ducts and the resuspension of radioactive graphite particles in high temperature reactors. A new numerical approach is suggested to simulate the particle resuspension off a multilayer deposit initially at rest in the cavity of horizontal obstructed turbulent channel flow. The present resuspension model is based on alternating iterations of a Large Eddy Simulation (LES) for the gas flow and a Discrete Element Method (DEM) for the particle detachment. The combination of LES and DEM simulates the effect of a sudden increase in the turbulent gas flow on the topology of the granular interface, i.e. the surface separating the multilayer deposit from the turbulent gas phase. After tuning two parameters of a simple cluster re-entrainment criterion, results show good agreements with experimental data performed on-site. Both the shape and the wall roughness of the granular interface are predicted with a good level of accuracy. Findings from this study also confirm that the friction velocity is a major resuspension agent.

In the following chapter, the authors conduct a literature survey of current advances in state-of-the-art low-cost, flexible electronics. A new emerging trend in the design of modern semiconductor devices dedicated to scaling-up, rather than reducing, their dimensions is presented. To realize volume manufacturing, alternative semiconductor materials with superior performance, fabricated by innovative processing methods, are essential. This review provides readers with a general overview of the material and technology evolution in the area of macroelectronics. Herein, the term macroelectronics (MEs) refers to electronic systems that can cover a large area of flexible media. In stark contrast to well-established micro- and nano-scale semiconductor devices, where property improvement is associated with downscaling the dimensions of the functional elements, in macroelectronic systems their overall size defines the ultimate performance (Sun and Rogers in Adv. Mater. 19:1897–1916, 2007). The major challenges of large-scale production are discussed. Particular Attention has been focused on describing advanced, short-term heat treatment approaches, which offer a range of advantages compared to conventional annealing methods. There is no doubt that large-area, flexible electronic systems constitute an important research topic for the semiconductor industry. The ability to fabricate highly efficient macroelectronics by inexpensive processes will have a significant impact on a range of diverse technology sectors. A new era “towards semiconductor volume manufacturing. . .” has begun.
The chapter is organized in three main sections. The candidate materials for flexible, large-area electronics (LAEs) are discussed in Sect. 14.1. Given the Limitation of this chapter, only selected groups of the semiconductors are presented. The target materials are Si-based inorganic thin-films and their intriguing, organic competitors. The general attributes of the materials suitable for macroelectronics are revised. The challenges associated with volume manufacturing with emphasis on the evolution of the heating technologies are demonstrated in Sect. 14.2. The final conclusions along with the authors’ considerations on the LAEs’ perspectives are given in Sect. 14.3.

The novel method of measuring the floatability of individual mineral phases on an ore cross section is presented. Combining atomic force microscopy with Raman spectroscopy can make use of hydrophobic effects to evaluate the hydrophobization of surfaces, a crucial microprocess of flotation. This paper presents comparative results of classic microflotation experiments and the new method looking at pure mineral samples of magnetite and quartz using simple anionic and cationic collectors. The mapping capabilities and identification of mineral phases with Raman spectroscopy is presented for a silicate type or from southern Sweden containing the mineral eudialyte rich in heavy rare earth elements. We show theoretically and experimentally the different possibilities to determine hydrophobic effects using force spectroscopy and the colloidal probe technique with a hydrophobic colloid attached to the cantilever of an atomic force microscope. This novel concept shall not only be a plain research tool but should help to simplify the investigation of the right flotation reagent and thus optimize flotation processes.

Reconstitution of membrane proteins in a native-like lipidic environment is crucial for the in vitro determination of their structural and functional properties. Nanoscale protein-bounded planar lipid bilayers, so-called Nanodiscs1, provide a versatile novel model membrane system into which membrane proteins can be incorporated in a monodisperse and active form being accessible from both sides of the membrane. They exhibit less scatter than liposomes and bicelles and are soluble in aqueous solution. We succeeded in the reconstitution of the evolutionary conserved P-type ATPase CopA from Legionella pneumophila into Nanodiscs, which is a key player in copper homeostasis throughout all kingdoms of life2. This provides us with an excellent platform for spectroscopic studies of the allosteric couplings that are associated with ATP-powered copper transport in this enzyme in fully controllable lipidic environments. Our current focus lies on the real-time observation of the allosteric coupling of the cytosolic nucleotide-binding domain to the intramembranous conserved copper-binding CPC-motif (cysteine‒prolin‒cysteine) in transmembrane helix 4. Moreover, the CopA‒Nanodisc system allows addressing specifically the influence of the lipid environment in the catalytic cycle. We are particularly interested in the role of water entry into the transmembrane region at specific catalytic intermediates. To this end, we use cysteine-reactive fluorophores as molecular probes for the physical environment of the copper-binding CPC-motif. Comparison between mutated versions of the CPC-motif enables a detailed view of structural transitions in the transmembrane part of the enzyme evoked by allosteric coupling. The biochemical platform represented by the Nanodiscs also opens new routes for the analysis of structural dynamics by time-resolved fluorescence spectroscopy. Our presented data on the copper-binding site hydration can be interpreted in the context of conformational changes proposed from crystal structures of CopA3.

References
1. T.H. Bayburt, S.G. Sligar. FEBS Lett. 2010, 584, 1721–1727.
2. J.M. Argüello, E. Eren, M. González-Guerrero. Biometals, 2007, 20, 233–248.
3. M. Andersson, D. Mattle, O. Sitsel, T. Klymchuk, A.M. Nielsen, L.B. Møller, S.H. White, P. Nissen, P. Gourdon. Nat. Struct. Mol. Biol. 2013, 21, 43–50.

For the long-term safety assessment of nuclear waste repositories, neptunium and uranium are two of the most environmentally relevant components of nuclear waste to be considered. Hence, great attention is attracted to their geochemistry and migration behavior. Among the various geochemical processes, the migration of radioactive contaminants in the environment is strongly affected by molecular reactions in aqueous solution and at the solid-water interface, e.g. complexation with organic/inorganic ligands, sorption onto mineral phases, surface precipitation, and colloid formation. A detailed description of these interactions on a molecular level is required for a reliable modeling of the contaminants dissemination in the environment.
In the past decade, vibrational spectroscopy has been developed to a powerful tool for the study of dissolved complexes of heavy metal ions with a variety of inorganic and organic ligands and surface complexes on solid phases. In particular, a combined approach of in situ vibrational, time-resolved laser fluorescence and X-ray absorption spectroscopy potentially provides comprehensive molecular information. A survey of very recent spectroscopic results obtained from geochemical reactions of radionuclides, namely Np(V) and U(VI), is given.

The present work deals with particle re-entrainment from a multilayer deposit exposed to a sudden flow increase. An early model is suggested to simulate the multilayer remobilisation of solid aerosol particles. The work is decomposed in two parts: 1. an algorithm is first developed for the virtual reconstruction of the multilayer deposit given its porosity and 2. particle detachment off the deposit is coupled with computational fluid mechanics. Experimental observations have shown that the clustering effect plays an important role in multilayer resuspension. Particle aggregates, and not individual particles, tend to reenter the turbulent flow. A cluster identification procedure is therefore suggested to work out resuspendable particle clusters. The condition of cluster dislocation is based on a force-balance model. The cluster detachment off the multilayer deposit occurs whenever the aerodynamic force overcomes the adhesive force. The turbulent flow was computed with a large eddy simulation. The numerical results showed satisfactory agreement with experimental data. Findings from that study showed that the wall shear stress is a main resuspension agent. Results have a direct impact for the safety assessment of gas-cooled high temperature reactor, in which the remobilisation of radioactive graphite particles occurs.

A large variety of systems are subject to slow and lengthy processes of solid aerosol particle deposition in turbulent flows. As a result of a long exposure to deposition, a multilayer particle bed eventually forms over time. Notable examples are the formation of multilayer deposits in ventilation ducts, in nuclear reactors or on earth surfaces subject to atmospheric sedimentation. Simulations are of great importance to predict the multilayer deposition of solid aerosol particles. Theoretical models are quite limited since their complexity rapidly increases when the flow becomes turbulent and the surface geometry complex. The present study proposes a new three-dimensional approach to reproduce the growth of a multilayer deposit in a turbulent obstructed channel flow at Reynolds number Re = 10, 000. Computational Fluid Dynamics and Computational Granular Dynamics are brought together to simulate four hours of real deposition. A detached eddy simulation is employed to predict particle deposition while self-organised criticality is employed to reproduce the slow growth of the multilayer deposit. The three dimensional shape of the multilayer deposit matches remarkably well the experimental data.

We describe a new design and experimental technique for point-contact spectroscopy in non-destructive pulsed magnetic fields up to 70 T. Point-contact spectroscopy uses a quasi-dc four-point measurement of the current and voltage across a spear-anvil point-contact. The contact resistance could be adjusted over three orders of magnitude by a built-in fine pitch threaded screw. The first measurements using this set-up were performed on both single-crystalline and exfoliated graphite samples in a 150ms, pulse length 70 T coil at 4.2K and reproduced the well known point-contact spectrum of graphite and showed evidence for a developing high field excitation above 35 T, the onset field of the charge-density wave instability in graphite.

For the long-term safety assessment of a nuclear waste repository it is necessary to know which microorganisms are present in the potential host rocks (e.g., clay) and how these microorganisms can influence the performance of a repository. The Opalinus clay layer of the Mont Terri Underground Rock Laboratory (Switzerland) is one potential host rock for nuclear waste disposal (1). It is well known that indigenous bacteria in such underground environments can affect the speciation and the mobility of actinides (2-4).
In this study, the unknown interaction between Pu and Sporomusa sp. MT-2.99 and Paenibacillus sp. MT-2.2 cells were explored in aqueous solution at pH 6. Both bacteria were isolated from Mont Terri Opalinus clay core samples. The time-dependent Pu concentrations measured in the supernatants were successfully fitted with bi-exponential decay functions. The time-dependent Pu oxidation state distributions were successfully fitted by using mono-exponential decay or growth functions.
To conclude, a moderate to strong impact of Sporomusa sp. and Paenibacillus sp. cells on the Pu speciation was observed. Differences in the Pu interaction process of both strains for instance depend on the presence or absence of an electron donor were detected and will be discussed in detail.

REFERENCES
1. M. Thury, P. Bossart, “The Mont Terri Rock Laboratory, a new international research project in a Mesozoic shale formation, in Switzerland” Eng. Geol., 52, 347-359 (1999).
2. J.R. Lloyd, G.M. Gadd, “The Geomicrobiology of Radionuclides” Geomicrobiol. J., 28, 383-386. (2011).
3. L. Lütke, H. Moll, V. Bachvarova, S. Selenska-Pobell, G. Bernhard, “The U(VI) speciation influenced by a novel Paenibacillus isolate from Mont Terri Opalinus clay” Dalton Trans., 42, 6979-6988 (2013).
4. M.P. Neu, G.A. Icopini, H. Boukhalfa, “Plutonium speciation affected by environmental bacteria” Radiochim. Acta, 93, 705-714 (2005).

The thermal processing of materials ranges from few femtoseconds by Swift Heavy Ion Implantation to about one second using advanced Rapid Thermal Annealing. This book offers after an historical excursus selected contributions on fundamental and applied aspects of thermal processing of classical elemental semiconductors and other advanced materials including nanostructures with novel optoelectronic, magnetic, and superconducting properties. Special emphasis is given on the diffusion and segregation of impurity atoms during thermal treatment. A broad range of examples describes the solid phase and/or liquid phase processing of elemental and compound semiconductors, dielectric composites and organic materials.

We present pump-probe experiments on graphene, which reveal a pronounced dependence of the pump-induced transmission on the angle between pump and probe polarization. It reflects a strong anisotropy of the pump-induced occupation of photogenerated carriers in momentum space. Within 150 fs after excitation an isotropic carrier distribution is established. The experiments are well described by microscopic modelling, which identify carrier-phonon scattering to be the main relaxation mechanism giving rise to an isotropic carrier distribution.

Clay formations (e.g. Opalinus Clay in Switzerland) are intended to serve as a host rock for the geological disposal of high- and intermediate-level long-lived radioactive waste in several European countries. Besides radionuclides, waste form like bituminized intermediate-level long-lived radioactive waste, harbour large amounts of additional components (e.g. organics, NaNO3 and CaSO4) which could perturb the beneficial physico-chemical barrier properties of the clay. To study the fate of leaching nitrate and organics in a clay formation, an in situ experiment, called Bitumen-Nitrate-Clay interaction (BN) experiment, was installed in the Opalinus Clay. The BN experiment aims to clarify the biochemical and chemical processes that could potentially be introduced by this nitrate and organic plume within the host clay formation.
As an active microbial community can have a significant contribution on the physical and (geo)chemical conditions of the surrounding clay, microbial analyses were performed. Our microbial investigation indicates that the present microbial community responds, and at the same time contributes, to the changing properties of the clay rock. As soon as nitrate becomes available a shift towards nitrate reduction appears. If in parallel easily oxidizable organics are introduced, like acetate, the community composition does not alter that much but the nitrate reduction rate is increased.

Inhalt:

Teil 1: Rohstoffwirtschaft
Teil 2: Primäre Rohstoffe
Teil 3: Sekundäre Rohstoffe und Recycling
Teil 4: Verarbeitung und Produkte

We present recent progress in the field of ion-implanted diamond-like carbon thin films. The phase transformation mechanism from an insulating sp3 matrix into a well-conducting sp2-rich graphite-like carbon phase by means of focused ion beam irradiation is investigated. The resistivity decrease is compared for the implantation of different ion species at 30 keV. It is shown that the sp3-to-sp2-conversion saturates at an Ga+ ion fluence of approximately 1 x 1015 cm-2. Nevertheless, further ion irradiation yields a continued drop of the film resistivity. Raman spectroscopy and transmission electron microscopy analysis show that ion-induced ordering proceeds at high fluences above the sp3-to-sp2-conversion saturation. This ordering can be considered as a microstructural transformation into a more graphite-like arrangement. We show that the increase of atomic ordering correlates with the local energy density deposited during the ion impact and furthermore, the resistivity lowering correlates with the degree of graphitization. The ion-induced phase transformation of diamond-like carbon layers is thus proposed to comprise a rehybridization stage (sp3-to-sp2-conversion), driven by nuclear collisions, and a rearrangement stage (graphitic ordering) that is thermally driven by the ion impact.

The development of contactless flow meters is an important issue for monitoring and controlling of processes in different application fields, like metallurgy, liquid metal casting, or cooling systems for nuclear reactors and transmutation machines. Shercliff described in his book “The Theory of Electromagnetic Flow Measurement, Cambridge University Press, 1962” a simple and robust device for contact-less measurements of liquid metal flow rates which is known as magnetic flywheel. The sensor consists of several permanent magnets attached on a rotatable soft iron plate. This arrangement will be placed closely to the liquid metal flow to be measured, so that the field of the permanent magnets penetrates into the fluid volume. The flywheel will be accelerated by a Lorentz force arising from the interaction between the magnetic field and the moving liquid. Steady rotation rates of the flywheel can be taken as a measure for the mean flow rate inside the fluid channel. The present paper provides a detailed theoretical description of the sensor in order to gain a better insight into the functional principle of the magnetic flywheel. Theoretical predictions are confirmed by corresponding laboratory experiments. For that purpose, a laboratory model of such a flow meter was built and tested on a GaInSn-loop under various test conditions.

The suitability of rare earth doped metal-oxide-semiconductor structures for optoelectronic applications is investigated. To do so, several Tb- and Er-doped devices with different designs and fabricated by different methods are compared among each other with respect to their electroluminescence (EL) properties. In detail, the investigated devices show EL power efficiencies between 2×10-4 and 2×10-3 which, taken individually for Tb and Er, have a linear dependence on the EL decay time for low and medium injection current densities. The excited fraction of Er ions is significantly higher than that of Tb ions and achieves a maximum value of 50% (with a maximum uncertainty factor of 2.25) under optimum conditions.

Extensive first-principle calculations on embedded clusters containing few O, Y, Ti, and Cr atoms as well as vacancies are performed to obtain interaction parameters to be applied in Metropolis Monte Carlo simulations, within the framework of a rigid lattice model. A novel description using both pair and triple parameters is shown to be more precise than the commonly used pair parameterization. Simulated annealing provides comprehensive data on the energetics, structure and stoichiometry of nm-size clusters at . Additionally, Metropolis Monte Carlo simulations are carried out at high temperature in order to investigate the dependence of nanocluster composition on temperature. The absolute value of the binding energy per O atom unit increases with cluster size and approaches a constant for large clusters. The presence of Ti and/or vacancies increases the value of this quantity. In alloys without vacancies clusters show a planar structure, whereas the presence of vacancies leads to three-dimensional configurations. Cr is not part of the nanoclusters, except for alloys without Ti but with vacancies. In the latter case clusters consist of a core containing O, vacancies, as well as Y and a Cr shell, which was also observed experimentally. A good agreement between the existing experimental data on the ratios (Y+Ti):O, Y:Ti, (Y+Cr):O, and Y:Cr, and the simulation results is found. The comparison of experimental data with those obtained by simulations demonstrates that the assumption of nanoclusters consisting of nonstoichiometric oxides that are essentially coherent with the bcc lattice of the Fe-Cr matrix leads to reasonable results.

Introduction: Modified fractionation radiotherapy (RT), delivering multiple fractions per day or shortening the overall treatment time, improves overall survival for non-small-cell lung cancer (NSCLC) patients compared with conventional fractionation RT (CRT). However, its cost effectiveness is unknown. Therefore, we aimed to examine and compare the cost effectiveness of different modified RT schemes and CRT in the curative treatment of unresected NSCLC patients. Methods: A probabilistic Markov model was developed based on individual patient data from the meta-analysis of radiotherapy in lung cancer (N = 2000). Dutch health care costs, quality-adjusted life years (QALYs), and net monetary benefits (NMBs) were compared between two accelerated schemes (very accelerated RT [VART] and moderately accelerated RT [MART]), two hyperfractionated schemes (using an identical (HRTI) or higher (HRTH) total treatment dose than CRT) and CRT. Results: All modified fractionations were more effective and costlier than CRT (1.12 QALYs, €24,360). VART and MART were most effective (1.30 and 1.32 QALYs) and cost €25,746 and €26,208, respectively. HRTI and HRTH yielded less QALYs than the accelerated schemes (1.27 and 1.14 QALYs), and cost €26,199 and €29,683, respectively. MART had the highest NMB (€79,322; 95% confidence interval [CI], €35,478-€133,648) and was the most cost-effective treatment followed by VART (€78,347; 95% CI, €64,635-€92,526). CRT had an NMB of €65,125 (95% CI, €54,663-€75,537). MART had the highest probability of being cost effective (43%), followed by VART (31%), HRTI (24%), HRTH (2%), and CRT (0%). Conclusion: Implementing accelerated RT is almost certainly more efficient than current practice CRT and should be recommended as standard RT for the curative treatment of unresected NSCLC patients not receiving concurrent chemo-radiotherapy. Copyright © 2013 by the International Association for the Study of Lung Cancer.

Bioaccumulation experiments, together with transmission electron microscopy together with electron energy loss spectroscopy (TEM/EELS) and confocal laser scanning microscopy (CLSM) were used to study the uranium uptake by metabolically active Euglena mutabilis cells and by dead biomass of Euglena mutabilis cells. For the experiments the Euglena cells were separated from the culture medium and placed in 1×10-5 M and 5×10-4 M uranyl solution (in Na2SO4 medium) at pH 3, respectively to relate to uranium contaminated acid mine drainage conditions and the uranium uptake was monitored over time. It was found that the immobilization by living Euglena cells is a slow but metabolically driven active process which takes up to 10 days, before it reaches equilibrium with the surrounding bulk solution. However, this active process leads to higher amounts of immobilized uranium in comparison to the fast immobilization of uranium by comparable amounts of dead biomass, which is completed within 20 to 25 minutes.
The immobilization of uranium by dead biomass is a different process. Here, uranium could only be observed in some instances on the Euglena pellicle by EF-TEM/EELS in concentrations close to the detection limit. This process was interpreted as a passive but very fast biosorption process in which uranium was eventually heterogeneously distributed as adsorbed species on accessible Euglena surfaces coordinated to carboxyl and also possibly to phosphate groups.
CLSM studies showed that uranium was transported into living Euglena cells. The respective fluorescence spectra obtained from the interior of the cell indicated a uranium phosphate or uranium carboxyl speciation. No such signals could be obtained for dead Euglena biomass, neither on E. mutabilis surfaces nor in the cells.
The above shown results showed that Euglena mutabilis cells do have the capacity to remove very mobile uranium(VI) species under AMD relevant conditions and could be a promising microorganisms for low-maintenance remediation strategies.

We demonstrate the lasing performance in the Nd:YAG ceramic channel waveguide produced by the carbon ion irradiation, including the continuous-wave (cw) and graphene Q-switched configurations. The highest slope efficiency of 56% and the lowest threshold of 40 mW have been obtained for the cw waveguide laser. With graphene as a saturable absorber, the Q-switched laser produces stable pulses with 57 ns pulse duration and 77 nJ pulse energy, respectively. Under the variation of the pumping power, the repetition of the pulse laser could be modified from 1.5 MHz to 4.1 MHz.

Particle therapy PET (PT-PET) has been established for dose monitoring and particle range assessment in hadron therapy. Imaging is up to now restricted to static organs. However, by means of phantom irradiation it has been shown that a 4D maximum likelihood expectation maximization (4D MLEM) reconstruction method is able to compensate for blurring artefacts of regular motion in in-beam PET images. Nevertheless, respiratory curves often show inconsistent amplitude variation, frequency modulation and baseline drift during radiotherapy. Since the anatomical information is not updated by a CT scanner during treatment, transformation of data from each phase could only rely on the 4D CT obtained prior to irradiation, which might be incorrectly transformed. Based on that clinical situation, this study aims to investigate the effect of irregularity in motion on 4D PET image reconstruction.

The qualitative positron emission tomography for the dose monitoring in ion beam therapy (PT-PET) has been approved for static tumors under clinical conditions. The detection of dose deviations is based on a comparison between the measured and an anticipated β⁺-activity distribution. Also for intra-fractionally moving targets, the 4D simulation as well as the 4D reconstruction of in-beam PET data has been established. Within dedicated experiments the results of the comparison between measured and anticipated activities were investigated with regard to the detection of failures in the motion mitigated ion beam delivery.

Particle therapy PET (PT-PET) is a clinically approved method for the verification of ion beam therapy. The evaluation of the obtained images is based upon the comparison of the measurement and a prediction. A new approach for the simulation of the activity distribution using measured yields in reference materials has recently been published. This approach provides the possibility to take the elemental composition of the different tissues into account. In this work first results of simulation in real patient cases are presented.

Purpose: Particle Therapy Positron Emission Tomography (PT-PET) is a suitable method for verification of therapeutic dose delivery by measurements of irradiation-induced β+-activity. Due to metabolic processes in living tissue β+-emitters can be removed from the place of generation. This washout is a limiting factor for image quality. The purpose of this study is to investigate whether a washout model obtained by animal experiments is applicable to patient data.
Methods: A model for the washout has been developed by Mizuno et al. [Phys. Med. Biol. 48(15), 2269–2281 (2003)] and Tomitani et al. [Phys. Med. Biol. 48(7), 875–889 (2003)]. It is based upon measurements in a rabbit in living and dead conditions. This model was modified and applied to PET data acquired during the experimental therapy project at GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, Germany. Three components are expected: A fast one with a half life of 2 s, a medium one in the range of 2–3 min, and a slow component of the order of 2–3 h. Ten patients were selected randomly for investigation of the fast component. To analyze the other two components, 12 one-of-a-kind measurements from a single volunteer patient are available.
Results: A fast washout on the time scale of a few seconds was not observed in the patient data. The medium processes showed a mean half life of 155.7 ± 4.6 s. This is in the expected range. Fractions of the activity not influenced by the washout were found.
Conclusions: On the time scale of an in-beam or in-room measurement only the medium-time washout processes play a remarkable role. A slow component may be neglected if the measurements do not exceed 20 min after the end of the irradiation. The fast component is not observed due to the low relative blood filled volume in the brain.

The capability of ion beam sputtering (IBS) to induce surface nanopatterns on different materials (metals, semiconductors or insulators) is well-known since the early 60’s [1]. The first description of such phenomenology was proposed by Bradley and Harper (BH) [2] invoking the interplay between surface relaxation mechanisms and the sputtering yield dependence on the local surface curvature. BH model and posterior generalizations [1] predict pattern formation for any ion incidence angle and successfully account for the observation of nanoripple or nanodot structures depending on the irradiation geometry (anisotropic or isotropic, respectively). However, the universality of the BH approach has been recently questioned by the disparity of (sometimes conflicting) results. This ambiguous scenario has been partially clarified after the awareness of the role played by compositional modifications during IBS for both monoelemental [3] and binary [4] semiconductors and, specially, for nanodot pattern formation. In these studies, silicon has become a sort of model system due to its technological relevance but also from the mono-elemental nature as well as extreme flatness. Thus, IBS of silicon surfaces yields (ripple) pattern formation only above an incidence angle threshold (~45° for low-energy Ar+ [5]) unless (metal) impurities prone to react with the target (forming silicides) are inadvertently or intentionally added during the irradiation [6,7]. Despite the a-priori undesirable presence of impurities, IBS with simultaneous co-deposition has emerged as a novel method to tune and modify the pattern morphology and characteristics [6-10]. In addition, the morphological pattern is correlated with a compositional one, offering new potential applications. However, assessing such compositional variations at the nanoscale is not straightforward and demands of advanced characterization tools. In this talk, the present status of metal co-deposition during low- (< 10 keV) and medium-energy (10-200 keV) IBS of silicon surfaces will be presented, making special emphasis on the efforts to elucidate correlated morphological and compositional issues.

[1] J. Muñoz-García, L. Vázquez, R. Cuerno, M. Castro, R. Gago, “Toward Functional Nanomaterials: Self-organized surface nanopatterning by IBS” pp.323-398 (Springer, 2009); [2] R.M. Bradley, J.M.E. Harper, J. Vac. Sci. Technol. A 6, 2390 (1988); [3] G. Ozaydin et al. Appl. Phys. Lett. 87,163104 (2005); [4] S. Le Roy et al. J. Appl. Phys. 106, 094308 (2009); [5] M. Castro, R. Gago et al. Phys. Rev. B 86, 214107 (2012) ; [6] J.A. Sánchez-García, R. Gago et al. J. Phys.: Condens. Matter 21, 224009 (2009); [7] H. Hofsäss et al. Appl. Phys. A 111, 653 (2013); [8] J.A. Sánchez-García, L. Vázquez, R. Gago et al. Nanotechnology 19, 355306 (2008); [9] K. Zhang et al. New J. Phys. 13, 013033 (2011); S. Macko et al. New J. Phys. 13, 073017 (2011); [10] A. Redondo-Cubero, R. Gago et al. Phys. Rev. B 86, 085436 (2012).

The low temperature (T = 5–40 K) capture of free electrons into hydrogenlike antimony centers in germanium has been studied by a time-resolving experiment using the free electron laser FELBE. The analysis of the pump-probe signal reveals a typical capture time of about 1.7 ns that decreases with pump energy to less than 1 ns while the number of ionized donors increases. The dependence on the pump-pulse energy is well described by an acoustic phonon-assisted capture process. In the cases when (i) a significant number of the electrons is in the conduction band (flux densities larger than 5 × 10^25 photons/(cm^2 s), (ii) the lattice temperature is above ∼20 K, or (iii) a static electric field above ∼2 V/cm is applied to the crystal, the pump-probe technique reveals an additional intraband relaxation process with a characteristic time of ∼100 ps, which is much shorter than that of the capture of free electrons into the antimony ground state.

Interaction with natural organic complexants such as humic substances can be decisive for the mobility of radiotoxic metals in case of release from an underground repository. Depending on the geochemical surroundings, their migration can be both enhanced and retarded. Models must be able to describe such complex systems by few parameters. According to the Linear Additive Model [1], total metal adsorption in the presence of humic matter is calculated by linking parameters for adsorption of both components and for their interaction with each other. The applicability of this approach is, however, not unanimously accepted.
Clay rock is discussed as a potential host formation for a final repository, mainly because of its high adsorption capacity. This barrier function may, however, be subverted by screening or competition effects due to high salt contents of pore waters. Complexation of radionuclides with humic-like clay organics may cause an additional mobilisation.
In this study, the influence of electrolyte concentration (up to 4 M) on interactions within the system Tb(III) / fulvic acid (FA) / Opalinus clay was investigated for the major electrolyte constituents of pore waters: Na+, Mg2+ and Ca2+. 160Tb was employed as a tracer analogue of trivalent actinides. FA (humic matter) was radiolabelled with 14C by an azo-coupling reaction. The sensitivity of radiotracer analysis allows experiments at low concentrations, in accordance with relevant scenarios. Complexation of Tb(III) with FA was investigated by means of ultrafiltration. For adsorption studies, clay suspensions were conditioned to a constant pH value of 5.0.
Effects of Na+, Mg2+ and Ca2+ proved to be very different. On the whole, interaction of Tb(III) with FA and clay is suppressed at increasing electrolyte contents, whereas interaction of FA with clay is promoted because electrostatic repulsion is screened. For this reason, mobilising effects of humic-like complexants are generally counteracted in saline systems; metals are solely mobilised due to common salt effects. For the bivalent electrolytes, these relationships can be quantitatively described by the Linear Additive Model.

[1] Zachara et al. (1994) Geochim. Cosmochim. Acta 58, 553-566.

No abstract available

The Sr2+ extraction properties of some 25,27-bis(carbonylmethoxy)calix[4]arenes, in which ester (-CH2CO2Et), keto (-CH2COCH3) and acid functionalities (-CH2CO2H) have been attached to the lower rim, are reported. Strontium ion extraction experiments were performed in a chloroform/water system, and the extraction performance analyzed by radiotracing using the short-lived radio nuclide 85Sr. Effects of pH value, ligand to metal ratio, temperature, extraction time and strontium species on the extraction behavior were examined. It was observed that the 25,27-bis(carboxymethoxy)calix[4]arene derivatives are potent extracting agents towards the strontium ion, showing remarkable extraction performance in competition with a series of organic and inorganic impurities and in a synthetic groundwater. The crystal structure of 25,27-bis(acetonyloxy)calix[4]arene is also reported.

The magnetization and sound propagation in single-crystalline ErFe₅Al₇ (tetragonal crystal structure) have been studied in steady (up to 18 T) and pulsed magnetic fields (up to 60 T). The compound orders ferrimagnetically at a Curie temperature T _C=201 K and has a compensation point at T _comp=34 K. ErFe₅Al₇ displays a strong magnetic easy-plane anisotropy. A strong magnetic anisotropy is present as well within the basal plane; the [100] axis is the easy magnetization direction with a spontaneous magnetic moment M _s=1.3 µ_B/f.u. at 2 K. Field-induced magnetic transitions, two along the [100] axis and two along the [110] axis, have been found in the vicinity of T=T _comp. Changes in the magnetic state at the transitions result in significant alterations of the spin–phonon coupling, which is manifested by sharp anomalies in the sound velocity and sound attenuation. Along the easy [100] axis the forced ferromagnetic state is reached in a field of about 50 T at 2 K, whereas along the [110] direction saturation is expected only above 60 T. A magnetic field-temperature phase diagram has been extracted up to 60 T. From the experimental data a value of n _ErFe=3.3 T/µ_B for the inter-sublattice Er–Fe exchange interaction has been obtained.

Thermodynamic parameters for the complex formation of Am(III) and Eu(III) with lactate were determined with UV-vis and time-resolved laser-induced fluorescence spectroscopy (TRLFS) in a temperature range between 25 and 70 °C. The reaction enthalpy decreased with increasing ionic strength. FT-IR and NMR spectroscopy in combination with density functional theory (DFT) calculations revealed structural details of the Eu(III) lactate complex: a chelating coordination mode of the lactate with a monodentate binding carboxylate group and the hydroxyl group being deprotonated.

Performance assessments of nuclear waste disposals evidenced 79Se (t1/2 ~ 3.27 × 105 years) to be one of the most important contributors to the overall dose in long-time safety assessments. The concentration, the bioavailability, the mobility, the distribution and the oxidation state of selenium in the environment are greatly influenced by the pH, nature of mineral sorbent and temperature. Hematite was studied because it is a ubiquitous iron oxide mineral present in the environment, thus often found in rocks and soils in the vicinity of underground repositories. This work combined batch and spectroscopic studies to characterize the interaction of Se(VI) and Se(IV) with hematite, which was so far not well understood.
At the macroscopic level, sorption of both oxyanions was found to decrease with increasing pH. An increase of the ionic strength (from 0.01 M to 0.1 M) decreased the sorption of Se(VI), while the Se(IV) uptake remained unchanged. Electrophoretic mobility measurements revealed that Se(IV) sorption shifted the isoelectric point (pHIEP) of hematite to lower pH values, while the pHIEP was not significantly modified upon Se(VI) uptake. At the molecular level, in situ ATR FT-IR and EXAFS measurements revealed the formation of inner-sphere complexes (IS) during Se(IV) sorption onto hematite. Concerning Se(VI), sorption proceeded predominantly via the formation of outer-sphere complexes, together with a small fraction of IS complexes.
High level and long-lived radioactive wastes are well-known to increase the temperature at the vicinity of the waste disposal site. Such a thermal effect raises the question how the retention of selenium is influenced at elevated temperatures. Therefore, information and insights about mechanisms working at higher temperatures (from 25 °C to 60 °C) are also provided.

Argillaceous rock and clay minerals have properties that make them very valuable for nuclear waste storage. They are practically insoluble and have high sorption capacities. North German clay deposits feature pore waters of particularly high ionic strengths. In the depths that are relevant for nuclear waste repositories, the ionic strength of the pore water ranges from 1.8 mol/l to 3.3 mol/l. To be able to make an informed decision about the long term safety of nuclear waste disposal, the effect of high ionic strengths on radionuclide retention needs to be taken into account.
This work focuses on the uranium retention on montmorillonite in sodium and calcium chloride solutions of high ionic strengths. Montmorillonite serves as a model clay. It is the main component of some North German clay formations that conform to the criteria for deep-level nuclear waste disposals. Furthermore, it is a component of the backfill material that will be used in nuclear waste repositories. Sodium and calcium chloride are the main constituents of the pore waters found in North German argillaceous rock. The sorption experiments presented here were conducted in presence and absence of carbon dioxide.

We discuss the performance of two global meteorological models in a difficult enclosed sea area and the possible improvements using two respectively nested high resolution local models. Each of the four sets of wind fields has been used to drive the same wave model. The performances are judged on the base of measured, buoys and satellites, wind and wave data. The analysis shows clearly the general benefits of a higher resolution. However, it also highlights the sensitivity of the nested models to apparently minor changes in the input information from the global models and their consequent possibility of larger errors, particularly in complex meteorological situations.

Spin-lattice effects play an important role in many magnetic materials. In this short review, we give some ex-amples of such effects studied in low-dimensional, frustrated as well as uranium-based antiferromagnets. Utiliz-ing ultrasound measurements at low temperatures and high magnetic fields provides valuable information on the spin-strain interactions. Specifically phase transformations and critical phenomena in magnetic systems with strong spin-lattice interactions are fruitful grounds for sound-velocity and sound-attenuation measurements.

In this paper, we have experimentally and numerically studied the nonradiative intersubband (ISB) relaxation in n-type Ge/SiGe quantum well (QW) systems. Relaxation times have been probed by means of pump-probe experiments. An energy balance model has been used to interpret the experimental differential transmission spectra and to assess the relevance in the nonradiative relaxation dynamics of both electron and lattice temperature as well as of the carrier density. The comparison between experimental data and theoretical simulation allowed us to calibrate the interaction parameters which describe the electron-optical phonon scattering in two-dimensional (2D) Ge systems. Characteristic relaxation times has been calculated and compared with those of GaAs QWs as a function of the 2D electron density, of the subband energy separation, and of the lattice and electronic temperature. We found that ISB relaxation times for the Ge/SiGe systems are generally shorter than that previously calculated when the electron distribution was neglected. Nonetheless, our main result is that the relaxation time in Ge/SiGe QW systems is longer than 10 ps, also for transition energies above the Ge optical phonon energy, up to 300 K. Furthermore, we obtained that the relaxation times are at least one order of magnitude longer than in GaAs-based systems.

First it will give a short overview about my expertise and background as well as the research topic I am working on at HZDR/IRE at the moment. Then I will present the results from our past contribution to the BN project. And finally I will give a short overview about what is planned for the next phase of the project from the HZDR/IRE.

Knowledge management is an instrument to ensure knowledge in organisations. The article defines the terms information and knowledge and the different kinds of knowledge. After a description why knowledge is important for organisations the term knowledge management and its objectives and tasks will be investigated. After that one of the first and famous models – the building block model from Probst et al. - will be explained.

The article discribes the current situation of commodity markets and the influence of the profit situation of industry companies and which contribution risk management can achieve to improve the economical situation of a company. One effective methode is to ensure commodity risks through financial instruments as a part of treasury management. The article describes the reasons and products of these method.

The article deals with the general conditions in energy industrie as a basis for new management tasks of energy supply companies. First, the changing market situation as a reason for the regulation will be explained, followed by the development of directives and regulations in european law and their impact on the german energy law. Finally, the influence of regulation on the legal structure and the organization as well as the accounting of energy supply companies will be shown.

TiAl-intermetallics show great potential for applications in high temperature-components due to their low density and excellent high-temperature strength. Their major drawback is the oxidation resistance at temperatures above 750°C. It has been shown that one way to improve this resistance by several orders of magnitude is the fluorination of the surface zone of the material. This fluorine treatment occurs at low temperatures and influences only the surface region of the components, so that the bulk properties are not affected. The fluorination changes the oxidation mechanism during subsequent oxidation exposure at temperatures higher than 750°C in such a way that the formation of a thick mixed oxide scale is replaced by the growth of a thin protective alumina scale. No additional coatings are necessary for the full protection of the substrate against further oxidation. One efficient and simple technique for bring the fluorine onto the TiAl surface is by using different liquid phases. This work focuses on the influence of liquid phase composition on the lifetime of the protective alumina layer. Possible beneficial synergistic effects between F and Si on the oxide nucleation behaviour are discussed in comparison to alternative fluorination methods such as plasma immersion ion implantation. Furthermore, the influence of the high temperature exposure needed for the initiation of the change in the oxidation mechanism of TiAl-alloys (i.e. conventional furnace exposure versus short-time laser treatment) on the stability of the protective character of alumina is examined.

Titanium aluminide (TiAl) alloys are attractive lightweight materials for medium-temperature (500°-750°C) structural applications including components such as jet engine and industrial gas turbine blades, turbocharger rotors and automotive engine valves. However, envisaged service temperatures for future advanced applications will have to be in the range of 750° to 1000°C, over which these alloys suffer from both oxidation and oxygen embrittlement. Therefore, development of surface-engineering techniques for preventing high-temperature environmental damage is critical in exploiting the advantages of TiAl alloys to their fullest extent. Two efficient approaches to protecting candidate TiAl alloys from high-temperature (>750°C) environmental degradation have been developed at HZDR. The first technique involves a single step, namely treating TiAl alloy components directly by plasma immersion ion implantation (PIII) of fluorine using a mixture of difluoromethane and argon (CH2F2 + 25% Ar) as the precursor gas. The oxidation performance of the fluorine-implanted alloys has been evaluated by thermal gravimetric analysis (TGA) over the temperature range of 750° to 1050°C under conditions of both isothermal and thermal cyclic oxidation in air, and for times as long as 6000 h. This type of surface modification has been shown to produce a stable, adherent and highly protective alumina scale. The second technique involves the fabrication of a durable protective coating in a two-step process, namely formation of a thin aluminum-rich TiAl layer (Ti-60Al) by chemical vapor deposition (CVD) employing a mixture of inorganic precursors, followed by PIII of fluorine. Subsequent long-term oxidation exposures to air at 900°C of a GE 4822 alloy (Ti-48Al-2Cr-2Nb; alloy composition qualified for aerospace applications) have shown that the coating so developed is able to successfully prevent oxidation damage to the base material while maintaining up to 90% of its initial mechanical properties (strength and ductility).

Titanium and its alloys with aluminum have been widely used as engineering materials for a number of advanced technical applications, and particularly in aeronautics, because of their high strength-to-weight ratio and good oxidation resistance in the medium temperature range (up to 500°C for Ti and ~ 750°C for TiAl). However, environmental durability at higher temperatures is presently still a concern due to insufficient oxidation and embrittlement resistance. Therefore, oxidation protection coatings are needed to fulfill the high temperature structural potential of these materials.
This work consists of two parts. The first part deals with the development of an oxygen barrier coating to prevent oxidation of Ti and low-Al-content Ti-base alloys (< 10 at.% Al) at temperatures not exceeding 600°C. The surface modification process has involved magnetron co-sputtering of Ti and Al onto the base alloy material followed by vacuum annealing and plasma immersion ion implantation (PIII) of fluorine to activate the so-called halogen effect. Oxidation exposure in air at 600°C for 100 h has shown that the coating is able to form a protective Al2O3-containing scale and, moreover, exhibits good substrate compatibility.
The second part of the work has focused on the development of an oxidation resistant coating for γ-TiAl alloys (Ti-48Al-2Cr-2Nb). The fabrication process has involved formation of an Al-rich (50-60 at.%) TiAl overlayer by chemical vapor deposition followed by PIII of fluorine. Subsequent oxidation exposures of the coated γ-TiAl alloy to air at 900°C for 350 h have shown that the coating prevents effectively both oxidation and embrittlement to the baseline material while preserving 90% of its initial mechanical properties.

Titanium alloys are widely used as light weight structural materials at low temperatures. Due to their high affinity towards oxygen a protective TiO2-passive layer is formed. This layer is only protective at temperatures below about 500°C. With increasing temperature this layer gets deteriorated and hence oxygen inward diffusion is accelerated. This inward diffusion leads to an oxygen enriched subsurface zone which is brittle because Ti has quite high oxygen solubility. The enriched zone can cause failure of Ti-components under thermocyclic and/or mechanical load. To prevent this failure mode a two step process was developed. The first step was enrichment of Al in a narrow surface zone to form the intermetallic TiAl-phase with low oxygen solubility and a high Al-content. The second step consisted of fluorination. Unfluorinated -TiAl-alloys usually form a mixed non protective oxide scale but a protective alumina layer develops after addition of small amounts of fluorine into the surface zone. This so called fluorine effect works for TiAl-alloys with an Al-content above 40at.%. The alumina layer suppresses the oxygen inward diffusion and slows down the oxidation kinetics. The intermetallic TiAl subsurface prevents oxygen uptake into the metal and, thus, embrittlement. In this work results of high temperature exposure tests of untreated and treated technical Ti-alloys will be presented and compared. The results will be discussed considering a use of protected Ti-components in high temperature environments.

Due to their excellent density-specific properties, titanium aluminide (TiAl) alloys have been identified as high-payoff materials for advanced aerospace and power generation applications in the medium-temperature (600°-750°C) range. They have recently been applied as structural materials for turbine blades in the low-pressure section of the GEnx jet engine. These alloys, however, are prone to both oxidation and embrittlement when exposed to oxidizing environments at temperatures above ~ 750°C. Under such conditions, TiAl alloys form a mixed (TiO2+Al2O3) non-protective oxide scale resulting from the difference in both the growth kinetics of the two oxides, and the chemical activity of the constituent elements, Ti and Al. Thus, for high-temperature (> 750°C) applications, an oxidation protection coating is needed to prevent environmental damage of the base alloy without degrading its initial mechanical properties.
The present work has focused on the development of coatings for the efficient oxidation protection of TiAl alloys at high temperatures. Aluminum-rich TiAl coatings (50 to 60 at.%Al) have been produced by either chemical vapor deposition (MO-CVD), physical vapor deposition (PVD) or thermal spraying (HVOF, APS) techniques onto a GE alloy (Ti-48Al-2Cr-2Nb) qualified for aerospace applications. The coating surface has then been modified by plasma immersion ion implantation (PIII) of fluorine to promote the formation of a protective alumina-containing scale relying on the so-called halogen effect. For the PIII processing, either difluoromethane and argon (CH2F2/Ar) or silicon tetrafluoride and argon (SiF4/Ar) has been used as the F-containing precursor gas. The resulting F-implanted coatings have been exposed to oxidative/corrosive environments at 850°C for 350 h, and have shown a high degree of oxidation resistance. The mechanical properties of the coated samples have been examined by 4-point bend, tensile and fatigue testing after oxidation in laboratory air at 900°C for 100 h. Combining a CVD process with PIII of F (the CH2F2/Ar process) has been found to give the best results in terms of efficient environmental protection against oxidation and embrittlement. It has also been established that more than 90% of the initial mechanical properties of the substrate TiAl alloy can be retained after the application of such a protective coating.

γ-TiAl alloys are attractive materials for medium-temperature (500-750°C) aeronautical applications. Current technology progress, however, is driven by the trend towards new concepts requiring temperatures > 750°C at which γ-TiAl components fail to perform because of poor oxidation and embrittlement resistance. We have developed two approaches to protecting γ-TiAl alloys from high-T oxidation. The first one involves treating γ-TiAl alloys by plasma-based ion implantation (PBII) of fluorine. This type of modification produces a highly protective Al2O3 scale upon oxidation in air at temperatures up to 1050°C. The second method is based on the fabrication of a protective coating in a two-step process, namely formation of an Al-rich TiAl overlay by chemical vapor deposition followed by PBII of F. Subsequent oxidation exposures to air at 900°C have shown that the coating prevents both oxidation and embrittlement to the base alloy while maintaining 90% of its initial mechanical properties.

Für eine neuartige Krebstherapie mit Protonen ist es wichtig zu wissen, welche Energie die Protonen haben. Für einen speziellen Detektor wurde eine automatische Auswertung entwickelt.

In ionization chambers, not all released charge is collected due to the recombination of charge carriers. This effect is taken into account by the saturation correction factor kS. A physical description of the correction factor has been established for pulsed radiation. However, it is only accurate when the pulse length is short compared with the collection time of the ionization chamber. In this paper we develop a description of the saturation correction for radiation pulses of arbitrary length. For this, a system of partial differential equations is solved iteratively. The numerical solutions are verified experimentally for a Roos ionization chamber (PTW TM34001) exposed to a pulsed electron beam. The results of this iterative procedure describe the experimental data well. The calculations are also possible for beam structures which are experimentally hard to get and thereby contribute to a better understanding and correct description of the saturation correction at arbitrary pulse length. Among other things the pulse length dependent distributions of the charge carriers in the ionization chamber is calculated, inclusive of the transition to the conditions prevailing in the case of continuous irradiation. Furthermore is shown that the formula for kS established by Hochhäuser and Balk [1] is applicable even at arbitrary pulse length, if pulse duration dependent effective values are used for the parameters a and p. These effective values have been determined for the Roos chamber at pulse lengths up to 300μs

Laser-accelerated electron pulses have been used to irradiate human tumors grown on mice’s ears during radiobiological experiments. These experiments have been carried out with the JETI laser system at the Institute of Optics and Quantum Electronics in Jena, Germany. To treat a total of more than 50 mice, a stable and reliable operation of the laser-electron accelerator with a dose rate exceeding 1 Gy/min was necessary. To achieve this, a sufficient number of electrons at energies in excess of 5 MeV had to be generated. The irradiation time for a single mouse was a few minutes. Furthermore, the particle pulses’ parameters needed to remain achievable for a time period of several weeks. Due to the online detection of the radiation dose, the unavoidable shot-to-shot fluctuations, currently still typical for laser-based particle accelerators, could be compensated. The results demonstrate that particle pulses generated with laser-based accelerators have the potential to be a future alternative for conventional particle accelerators used for the irradiation of tumors.

In ionization chambers not all released charge is collected due to recombination of charge carriers. A physical description of the correction factor has been established for pulsed beams for many decades. However, it is only accurate if the pulse length is short compared to the collection time of the ionization chamber. In this contribution a new, more generalized description of the Saturation correction (i.e. for arbitrary pulse lengths) is presented.
Experiments have been performed using a Roos ionization chamber (TM34001, PTW Freiburg, Germany) because this model is a planparallel chamber often used in clinics. The pulse length dependence was investigated at the superconducting electron linear accelerator ELBE. For the new theoretical description a system of partial differential equations is solved iteratively. The free parameters were adjusted for best agreement with the experiment.
The experiment shows, that the established description of saturation correction is only valid for pulses shorter than 10 μs. Furthermore, our new theoretical description allows the determination of Saturation correction in a wide range, e.g., for beam time structures which are experimentally difficult to realize and for longer pulse durations. Hereby the calculation results in a better understanding of the recombination process by giving insight into the dynamics of charge carrier distributions. In this way we can show that the established theoretical formalism is also valid at longer pulses, if the previoulsy used fixed parameters are reintroduced as pulse length dependent. For the Roos chamber the dependence of these parameters is demonstrated.

n ionization chambers not all released charge is collected due to recombination of charge carriers. A physical description of the correction factor has been established for pulsed beams for many decades. However, it is only accurate if the pulse length is short compared to the collection time of the ionization chamber. In this contribution a new, more generalized description of the Saturation correction (i.e. for arbitrary pulse lengths) is presented.
Experiments have been performed using a Roos ionization chamber (TM34001, PTW Freiburg, Germany) because this model is a planparallel chamber often used in clinics. The pulse length dependence was investigated at the superconducting electron linear accelerator ELBE. For the new theoretical description a system of partial differential equations is solved iteratively. The free parameters were adjusted for best agreement with the experiment.
The experiment shows, that the established description of saturation correction is only valid for pulses shorter than 10 μs. Furthermore, our new theoretical description allows the determination of Saturation correction in a wide range, e.g., for beam time structures which are experimentally difficult to realize and for longer pulse durations. Hereby the calculation results in a better understanding of the recombination process by giving insight into the dynamics of charge carrier distributions. In this way we can show that the established theoretical formalism is also valid at longer pulses, if the previoulsy used fixed parameters are reintroduced as pulse length dependent. For the Roos chamber the dependence of these parameters is demonstrated.

We report the results of a detailed mineralogical investigation of platinum-group minerals (PGM) and copper-gold nuggets from the Uktus Ural-Alaskan type complex in the Central Urals (Russia). The studied nuggets were sampled in alluvial-eluvial deposits from three small valleys, with temporary water flows, cutting across the Uktus massif. The volume of the washed samples varies from 0.03 to 0.08 m3 and a few tens of PGM nuggets, ranging in size from about 100 m m to about 2 mm, were collected. According to their chemical composition, the most abundant PGM are native Ir-Os and alloys in the Pt-Fe-Cu-Ni system. The following less abundant PGM were also recognised: sulfarsenides of the irarsite-hollingworthite-platariste series, sulfides such as laurite, cuproiridsite, kashinite and the sulfantimonide tolovkite. One alloy corresponding to the formula Cu3Au2 was found, and proved to be Cu-rich tetraauricupride. The nuggets of Uktus have, in some cases, a polygonal shape. However, most of them have an irregular morphology and are characterised by a porous rim and zoning. The investigated nuggets occur as single-phase crystals or as polyphase grains, composed of different PGM. One nugget displays a very complex texture, being composed of a Pt-Fe alloy associated with osmium and Cu-rich tetraauricupride. These minerals are in contact with quartz that contains minute inclusions of hollingworthite and platarsite. The mineralogical similarity with the PGM inclusions in the Uktus chromitites indicates these rocks as a possible source for the PGM nuggets. The presence of faceted morphology in some nuggets suggests that they were mechanically liberated and transported for a relatively short distance from their lode deposits. The nuggets characterized by a rounded shape and occurring in association with quartz and Cu-rich tetraauricupride have probably been reworked in the placer environment. Therefore, in the Uktus placers deposits, two types of PGM nuggets can coexist: (i) primary with a magmatic origin, i.e., only mechanically liberated from their source rock, and (ii) secondary, i.e., reworked and grown in the placers. The mineralogical assemblage of the Uktus PGM nuggets, the fact that the Uktus PGM placers have never been mined and the recent exponential increase in demand for noble metals make the placer deposits associated with the Uktus complex potentially important for the economic recovery of these rare metals, at least on a small scale.

We compare different optimization techniques for high average-power diode-pumped solid-state laser amplifiers currently developed at the PENELOPE project. Amplified spontaneous emission and thermally induced depolarization losses are the main limiting factors besides laser induced damage. Optimizing the laser gain medium geometry and the choice of the gain medium are the key factors for highly efficient laser amplifiers.

The Rossendorf Beamline ROBL at the ESRF is operated since 1998 by the Institute of Resource Ecology and Ion Beam Physics and Materials Research of the HZDR. In 2011-2012 the optics of the beamline such as mirrors double crystal monochromator and diagnostic was modernized to meet future experimental demands. The Materials Research Station is focusing on in-situ investigations. These are in thin film synthesis by magnetron sputtering, in-operando measurements on lithium ion batteries, surface modification by ion implantation and high temperature investigations using reactive atmosphere like in chemical vapor deposition (CVD) processes.
Iron nano-crystals are a common catalyst in the CVD growth reaction of carbon nano tubes. These crystals were formed by dewetting of the corresponding iron thin film at raised temperatures. Under reaction condition different iron phases such as Fe3C, alpha-Fe and gamma-Fe were detected. Their concentrations are strongly varying before, after and during the CVD process. This leads to the conclusion that besides Fe3C also metallic iron is catalytically active [1].
In graphene CVD nickel and copper are commonly used as catalyst. High resolution diffraction data were collected at reaction temperature. The lattice parameter was calculated using Lebail fit, corrected due to small shifts in sample surface temperature by the thermal expansion determined before. The results show a lattice expansion of nickel under different CVD atmospheres, indicating an uptake of hydrogen and carbon on interstitials in the metallic Ni. The carbon uptake is only partially reversible, but additional hydrogen can be assimilated .

Thomson backscattering of intense laser pulses from relativistic electrons not only allows for the generation of bright X-ray pulses but also for the investigation of the complex particle dynamics at the interaction point. For this purpose a complete spectral characterization of a Thomson source powered by a compact linear electron accelerator was performed with unprecedented angular and energy resolution. A rigorous statistical analysis comparing experimental data to 3D simulations enabled, e.g., the extraction of the angular distribution of electrons with 1.5% accuracy and, in total, provides predictive capability for future high brightness hard X-ray and potential gamma-ray sources. We further present a novel Thomson scattering geometry in order to avoid the restrictions on the X-ray photon yield imposed by the Rayleigh limit. The suggested traveling-wave setup (TWTS) allows an overlap of electron and laser beams, even after propagating over distances in the centimeter to meter range. Experimental designs are discussed and optimized for different scattering angles.

PURPOSE:

To investigate scanned-beam proton dose distribution reproducibility in the lung under high frequency jet ventilation (HFJV).
MATERIALS AND METHODS:
For 11 patients (12 lesions), treated with single-fraction photon stereotactic radiosurgery under HFJV, scanned-beam proton plans were prepared with the TRiP98 treatment planning system using 2, 3-4 and 5-7 beams. The planning objective was to deliver at least 95% of the prescription of 33 Gy (RBE) to 98% of the PTV. Plans were subsequently recomputed on localization CT scans. Additionally, for selected cases, the effects of range uncertainties were investigated.
RESULTS:
Median GTV V(98%) was 98.7% in the original 2-field plans and 93.7% in their recomputation (p=0.039). The respective values were 99.0% and 98.0% (p=0.039) for the 3-4-field plans and 100.0% and 99.6% (p=0.125) for the 5-7-field plans. CT calibration uncertainties of ±3.5% led to a GTV V(98%) reduction below 1.5 percentual points in most cases and reaching 3 percentual points for 2-field plans with beam undershoot.
CONCLUSIONS:
Through jet ventilation, reproducible tumor fixation for proton radiotherapy of lung lesions is achievable, ensuring excellent target coverage in most cases. In few cases, non-optimal patient setup reproducibility induced density changes across beam entrance channels, leading to dosimetric deterioration between planning and delivery.

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