Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The synthesis of a series of divalent and trivalent β-diketiminate borohydrides [(dipp)₂NacNacLn(BH₄)(THF)₂] ((dipp)₂NacNac = (2,6-C₆H₃iPr₂)NC(Me)CHC(Me)N(2,6-C₆H₃iPr₂); Ln = Sm, Eu, Yb) and [(dipp)₂NacNacLn(BH₄)₂(THF)] (Ln = Sc, Sm, Dy, Yb, Lu) is reported. All compounds were obtained by salt metathesis in THF from [(dipp)₂NacNacK] and the corresponding homoleptic divalent and trivalent borohydrides [Ln(BH₄)₂(THF)₂] (Ln = Sm, Eu, Yb), [Sc(BH₄)₃(THF)₂], and [Ln(BH₄)₃(THF)₃] (Ln = Sm, Dy, Yb, Lu), respectively. The complexes were fully characterized and their solid state structures were established by single crystal X-ray diffraction. In both the divalent and trivalent compounds, the BH₄ groups coordinate in a κ³(H) mode to the metal. Only in the lutetium complex [(dipp)₂NacNacLu(BH₄)₂(THF)] does one BH₄ group coordinate in a κ³(H) mode, whereas the other one coordinates as κ²(H). This kind of mixed κ²/κ³(H) coordination mode is rare. The application of the divalent and trivalent compounds as initiators in the ring-opening polymerization (ROP) of ε-caprolactone (CL) and trimethylene carbonate (TMC) was investigated. All complexes afforded a generally well-controlled ROP of both of these cyclic esters. High molar mass poly(ε-caprolactone)diols (Mn,NMR < 92 700 g/mol, ÐM = 1.51) and α-hydroxy,ω-formate telechelic poly(trimethylene carbonate)s (Mn,NMR < 16 000 g/mol, ÐM = 1.59) were thus synthesized under mild operating conditions.

Das, dem Teilprojekt zu Grunde liegende, Gesamtprojekt gliederte sich in zwei Module: In Modul A (Förderung durch das BMWi, Federführung durch KIT) und Modul B (Förderung durch das BMBF, Federführung durch acatech). Projektpartner im Modul A waren DBE TECHNOLOGY GmbH, die Gesellschaft für Anlagen- und Reaktorsicherheit mbH (GRS), das Helmholtz-Zentrum Dresden-Rossendorf (HZDR), das Karlsruher Institut für Technologie (KIT) und die Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen zusammen mit dem Forschungszentrum Jülich (FZJ). Modul B wurde vom Zentrum für Interdisziplinäre Risiko- und Innovationsforschung der Universität Stuttgart (ZIRIUS) bearbeitet. Die Gesamtkoordination der beidem Module erfolgte durch die Deutsche Akademie der Technikwissenschaften (acatech). Auf Grundlage einer Analyse der wissenschaftlich-technischen Aspekte durch Modul A wurden die gesellschaftlichen Implikationen bewertet und daraus in Modul B Kommunikations- und Handlungsempfehlungen für die zukünftige Positionierung von P&T formuliert.
Im, vom HZDR koordinierten, Teilprojekt „Stand der Grundlagen- und technologischen Forschung“ wird eine Übersicht über den genannten Bereich gegeben. Eingeführt wird das Thema mit einer Kurzbeschreibung möglicher Reaktorsysteme für die Transmutation. Danach wird der Entwicklungsstand der Spezialbereiche Trennchemie, Sicherheitstechnologie, Beschleunigertechnologie Flüssigmetalltechnologie, Entwicklung von Spallationstargets, Transmutationsbrennstoffen und Werkstoffkonzepten sowie Konditionierung von Abfällen, beschrieben. Dies wird ergänzt durch Spezifika von Transmutationsanlagen beginnend bei physikalischen Grundlagen und Kerndesigns, über Reaktorphysik von Transmutationsanlagen, Simulationstools und die Entwicklung von Safety Approaches. Im Anschluss wird der Stand existierender Bestrahlungseinrichtungen mit schnellem Spektrum beschrieben. Nachfolgend werden basierend auf dem derzeitigen Stand von F&E die offenen Fragen und Forschungslücken in den einzelnen Teilbereichen – Wiederaufbereitung und Konditionierung, Beschleuniger und Spallationstarget, Reaktor – zusammengestellt und sowohl eine Strategie, als auch ein Fahrplan zur Schließung der Technology Gaps entwickelt.
Zusätzlich werden die Hauptbeiträge, des HZDR zur Gesamtstudie beschrieben. Dies sind insbesondere die Beschreibungen der Möglichkeiten und Grenzen von P&T, die Herausforderungen an Bestrahlungseinrichtungen zur Transmutation und deren Effektivität, sowie Sicherheitsmerkmale beschleuniger-getriebener unterkritischer Systeme inclusive grundlegender Störfallbetrachtungen und Sicherheitscharakteristik.

Dr. Bruno Merk wirkte zusätzlich, sowohl in Modul B als Fachmann für Transmutation als auch bei der Erstellung der acatech POSITION als fachlicher Berater mit.

Abstract
The main project, where this sub project contributed to, has been structured into two modules: module A (funded by the federal ministry of economics, managed by KIT) and module B (funded by the federal ministry of education and research, managed by acatech). Partners in module A were DBE TECHNOLOGY GmbH, the Gesellschaft für Anlagen- und Reaktorsicherheit mbH (GRS), the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the Karlsruher Institute of Technology (KIT) and the Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen, in co-operation with the Forschungszentrum Jülich (FZJ). Modul B has been executed by the Zentrum für Interdisziplinäre Risiko- und Innovationsforschung der Universität Stuttgart (ZIRIUS). The overall coordination has been carried out by the Deutsche Akademie der Technikwissenschaften (acatech). The social implications have been evaluated in module B based on the analysis of the scientific and technological aspects in module A. Recommendations for communication and actions to be taken for the future positioning of P&T have been developed.
In the project part, coordinated by HZDR – status of R&D – an overview on the whole topic P&T is given. The topic is opened by a short description of reactor systems possible for transmutation. In the following the R&D status of separation technologies, safety technology, accelerator technology, liquid metal technology, spallation target development, transmutation fuel and structural material development, as well as waste conditioning is described. The topic is completed by the specifics of transmutation systems, the basic physics and core designs, the reactor physics, the simulation tools and the development of Safety Approaches. Additionally, the status of existing irradiation facilities with fast neutron spectrum is described. Based on the current R&D status, the research and technology gaps in the topics: separation and conditioning, accelerator and spallation target, and reactor are characterized and a strategy as well as a roadmap for closing these gaps has been developed.
In addition the major contributions of HZDR to the main project are described. The major parts are the description of the potential and the limits of P&T, the requirements and challenges for transmutation systems and the related efficiency, as well as the safety features of accelerator driven subcritical systems including the transient behavior and the safety characteristics.

Dr. Bruno Merk additionally contributed to module B as specialist for transmutation and acted as scientific advisor for the preparation of the acatech POSITION.

To evaluate the sensitivity of the positron emission tomography (PET) portion of fluorine-18 fluorodeoxyglucose- PET-computerized tomography (¹⁸F-FDG-PET/CT) to detect solid malignant renal masses, and to assess for metabolic differences based on histopathological type. Nineteen subjects with 25 known solid malignant renal masses who underwent ¹⁸F-FDG-PET/CT were retrospectively evaluated. Qualitative analysis of the PET portion only of ¹⁸F-FDG-PET/CT examinations to assess visual detection of renal masses was initially performed in blinded fashion. Subsequently, measurements of standardized uptake value (SUV) and lesion-to-background ratios were performed for all masses and compared between histopathological types. Of 25 solid malignant renal masses, 18 were renal cell carcinoma (RCC), 3 were renal lymphoma, and 4 were metastases. Twenty-two of 25 were detectable, and all were correctly spatially localized. Fifteen of 22 detectable lesions were exophytic in configuration. The three non-detectable masses were non-exophytic RCC's with average diameter of 2.0cm. Fifteen of 18 of RCC were detectable, whereas all renal lymphomas and metastases were detectable. None of the metabolic parameters were statistically significant between RCC and renal lymphoma. However, all metabolic parameters were statistically significantly greater for renal metastases compared to RCC and renal lymphoma, and for clear cell RCC compared to papillary RCC. In conclusion, the PET portion of ¹⁸F-FDG-PET/CT had a sensitivity of 88% for detection of solid malignant renal lesions in patients with known renal malignancy, and reveals differences in metabolic activity based on histopathological type, which may be useful for purposes of individualized medicine. Further studies are required for more in depth assessment of these preliminary observations.

Objectives: FDG-PET/CT has become the standard for staging of local tumor extent, mediastinal lymph node involvement and distant metastatic disease in patients with non-small-cell lung cancer (NSCLC). However, its role for prognosis is less clear. The aim of the present study was to evaluate the prognostic value of a novel quantitative measure for the spatial heterogeneity of FDG uptake, the asphericity (ASP).

Methods: FDG-PET/CT had been performed in 68 patients (65.5±8.8y) with newly diagnosed NSCLC prior to treatment. PET images of the primary tumor were segmented using the ROVER 3D segmentation tool based on thresholding at the volume-reproducible intensity threshold after subtraction of local background. ASP defined as the deviation of the tumor's shape from sphere shape was computed. Kaplan-Meier analysis with respect to progression-free (PFS) and overall survival (OS) was performed for localization (central vs. peripheral), SUVmax, metabolically active tumor volume (MTV), total lesion glycolysis (TLG) and ASP. OS and PFS curves were separated by the median value and compared by log-rank tests.

Results: 38 patients experienced tumor progression or recurrence after a median interval of 6.2 months (range 1.4-23.7). 28 patients died after a median interval of 7.1 months (0.4-19.4). The localization of the tumor was a predictor of both PFS (p=0.04, 2-year PFS 58% vs 45% for peripheral vs central localization) and OS (p=0.02, 2-year OS 57% vs 33%). ASP was the only PET-based parameter with prognostic value for PFS (p=0.005): the probability of 2-year PFS decreased from 60 % in the patients with low ASP to 47 % in the patients with high ASP. None of the PET-based parameters was predictive for OS.

Conclusions: The asphericity of the pretherapeutic FDG-uptake provides more power for the prediction of PFS in NCSLC than conventional quantitative measures including SUVmax, MTV and TLG.

Objectives: To generate quantitative parameters from dynamic Ga-68 DOTATOC PET (PET) as new markers for tumor perfusion and somatostatin receptor expression on gastroenteropancreatic NET.

Methods: PET was performed in 8 patients (pts) Images were acquired in list mode for 15 minutes after i.v. bolus injection. 63 regions of interests (spleen/adrenals, n=21; normal liver tissue, n=8; primary tumor/metastases (mets); n=34) were evaluated to generate k1, k2, k3, k4 and the fractional blood volume (fbv) using a reversable two compartment model.

Results: Mets in pts with proliferation rate (Ki67) 5-20% showed (n=12) significant higher k1, k2, k3, k4 (all p<0.01) compared to pts with lower Ki67 (<5%) (n=22) but significantly lower fbv (p<0.05). In liver (not receptor-specific uptake), k2 was signficantly higher (p<0.05) than in mets (median, 0.50 vs 0.23). SUVmax in mets showed significant correlations with k1 (rho, 0.37; p<0.001) und fbv (rho, 0.51; p<0.01) but not with k3. SUVmax in spleen/adrenal glands (receptor-specific uptake) correlated significantly with k3 (rho, 0.51; p<0.05).

Conclusions: These preliminary results, within its limitations (low pts number) suggests that dynamic Ga-68 DOTATOC PET enables segregation of tumor perfusion (fbv) from receptor specific binding (k1) in mets. Both parameters, fbv and k1, are primarily correlated to SUVmax in mets. The internalization of receptor ligand (Ga-68 DOTATOC) complexes (k3) appears to be mainly responsible for specific uptake in spleen and adrenal glands, while in normal liver a significantly higher washout of the ligand (k2) was observed which is in line with non-specific peptide uptake due to peptide metabolism in the liver. Moreover, mets in pts with higher Ki67 showed higher receptor ligand dynamics as denoted by higher k1-4 values.

Objective:

To propose a novel measure, namely the ‘asphericity’ (ASP), of spatial irregularity of FDG uptake in the primary tumour as a prognostic marker in head-and-neck cancer.

Methods:

PET/CT was performed in 52 patients (first presentation, n = 36; recurrence, n = 16). The primary tumour was segmented based on thresholding at the volume-reproducible intensity threshold after subtraction of the local background. ASP was used to characterise the deviation of the tumour’s shape from sphere symmetry. Tumour stage, tumour localisation, lymph node metastases, distant metastases, SUV_max, SUV_mean, metabolic tumour volume (MTV) and total lesion glycolysis (TLG) were also considered. The association of overall (OAS) and progression-free survival (PFS) with these parameters was analysed.

Results:

Cox regression revealed high SUV_max [hazard ratio (HR) = 4.4/7.4], MTV (HR = 4.6/5.7), TLG (HR = 4.8/8.9) and ASP (HR = 7.8/7.4) as significant predictors with respect to PFS/OAS in case of first tumour manifestation. The combination of high MTV and ASP showed very high HRs of 22.7 for PFS and 13.2 for OAS. In case of recurrence, MTV (HR = 3.7) and the combination of MTV/ASP (HR = 4.2) were significant predictors of PFS.

Conclusions:

ASP of pretherapeutic FDG uptake in the primary tumour improves the prediction of tumour progression in head-and-neck cancer at first tumour presentation.

Scattering scanning near-field optical microscopy (s-SNOM) has been established as an excellent tool to probe domains in ferroelectric crystals at room temperature. Here, we apply the s-SNOM possibilities to quantify low-temperature phase transitions in barium titanate single crystals by both temperature-dependent resonance spectroscopy and domain distribution imaging. The orthorhombic-to-tetragonal structural phase transition at 263 K manifests in a change of the spatial arrangement of ferroelectric domains as probed with a tunable free-electron laser. More intriguingly, the domain distribution unravels non-favored domain configurations upon sample recovery to room temperature as explainable by increased sample disorder. Ferroelectric domains and topographic influences are clearly deconvolved even at low temperatures, since complementing our s-SNOM nano-spectroscopy with piezoresponse force microscopy and topographic imaging using one and the same atomic force microscope and tip.

Calculated incision rates along the Panj, the main river of the Pamir, are used to investigate any influence by tectonics or climate on the architecture of the river. The depositional ages of Panj River terraces were calculated using optically stimulated luminescence (OSL) dating of terrace sand. Fluvial incision rates were generated by integrating the terrace depositional ages with accurate kinematic GPS measurements of terrace heights above the modern Panj. We investigated 16 terraces along the Panj at the western Pamir margin and one terrace from the Vakhsh River to the north of the Pamir. The results reveal brief periods of fluvial deposition over the past 26 kyr. The oldest Panj terrace depositional ages coincide with early MIS 2 and MIS 2/1 glaciations on the Pamir Plateau. Younger terrace ages have no apparent link with glacial cycles. Terraces with varying heights above the modern Panj at different localities yielded similar depositional ages. This suggests that local conditions have determined fluvial incision rates. Combining all of the terrace measurements, the average incision rate of the Panj over the last 26 kyr has been similar to 5.6 mm/yr. A high mean incision rate of similar to 7.3 mm/yr was calculated from terraces where the Panj has cut a steep-sided valley through the Shakhdara dome. Significantly lower incision rates (similar to 2-3 mm/yr) were calculated from terraces where the Panj flows along the southern boundaries of the Shakhdara and Yazgulom domes. At those localities, graded segments of the Panj River profile and increased valley widths are indicative of local base levels. Downstream of the Yazgulom dome, river incision rates are generally lower (similar to 4-5 mm/yr) than the Panj average.
However, there is one exception where higher incision rates (similar to 6 mm/yr) were calculated upstream of the Darvaz Fault Zone, a major tectonic feature that forms the western boundary of the Pamir. The Vakhsh River terrace to the north of the Pamir yielded a lower incision rate (similar to 3 mm/yr) compared to the Panj average. Variation in incision rates along the Panj does not correspond to changes in rock type or river catchment area. Instead, incision rates appear to have been primarily influenced by river capture across the southern and central metamorphic domes of the Pamir. Wherever the Panj cuts these domes it displays a convex river profile. The combination of localized river profile convexity and changes in incision rates across the Pamir domes indicates that the dome boundaries have been active recently.

Based on a 2 year seismic record from a local network, we characterize the deformation of the seismogenic crust of the Pamir in the northwestern part of the India-Asia collision zone. We located more than 6000 upper crustal earthquakes in a regional 3-D velocity model. For 132 of these events, we determined source mechanisms, mostly through full waveform moment tensor inversion of locally and regionally recorded seismograms. We also produced a new and comprehensive neotectonic map of the Pamir, which we relate to the seismic deformation. Along Pamir's northern margin, where GPS measurements show significant shortening, we find thrust and dextral strike-slip faulting along west to northwest trending planes, indicating slip partitioning between northward thrusting and westward extrusion. An active, north-northeast trending, sinistral transtensional fault system dissects the Pamir's interior, connecting the lakes Karakul and Sarez, and extends by distributed faulting into the Hindu Kush of Afghanistan. East of this lineament, the Pamir moves northward en bloc, showing little seismicity and internal deformation. The western Pamir exhibits a higher amount of seismic deformation; sinistral strike-slip faulting on northeast trending or conjugate planes and normal faulting indicate east-west extension and north-south shortening. We explain this deformation pattern by the gravitational collapse of the western Pamir Plateau margin and the lateral extrusion of Pamir rocks into the Tajik-Afghan depression, where it causes thin-skinned shortening of basin sediments above an evaporitic décollement. Superposition of Pamir's bulk northward movement and collapse and westward extrusion of its western flank causes the gradual change of surface velocity orientations from north-northwest to due west observed by GPS geodesy. The distributed shear deformation of the western Pamir and the activation of the Sarez-Karakul fault system may ultimately be caused by the northeastward propagation of India's western transform margin into Asia, thereby linking deformation in the Pamir all the way to the Chaman fault in the south in Afghanistan.

The objective of this study is to develop models based on both optical and L-band Synthetic Aperture Radar (SAR) data for above ground dry biomass (hereafter AGB) estimation in mountain forests. We chose the site of the Loveh forest, a part of the Hyrcanian forest for which previous attempts to estimate AGB have proven difficult. Uncorrected ETM+ data allow a relatively poor AGB estimation, because topography can hinder AGB estimation in mountain terrain. Therefore, we focused on the use of atmospherically and topographically corrected multispectral Landsat ETM+ and Advanced Land-Observing Satellite/Phased Array L-band Synthetic Aperture Radar (ALOS/PALSAR) to estimate forest AGB. We then evaluated 11 different multiple linear regression models using different combinations of corrected spectral and PolSAR bands and their derived features. The use of corrected ETM+ spectral bands and GLCM textures improves AGB estimation significantly (adjusted R2 = 0.59; RMSE = 31.5 Mg/ha). Adding SAR backscattering coefficients as well as PolSAR features and textures increase substantially the accuracy of AGB estimation (adjusted R2 = 0.76; RMSE = 25.04 Mg/ha). Our results confirm that topographically and atmospherically corrected data are indispensable for the estimation of mountain forest’s physical properties. We also demonstrate that only the joint use of PolSAR and multispectral data allows a good estimation of AGB in those regions.

Forest environment classification in mountain regions based on single-sensor remote sensing approaches is hindered by forest complexity and topographic effects. Temperate broadleaf forests in western Asia such as the Hyrcanian forest in northern Iran have already suffered from intense anthropogenic activities. In those regions, forests mainly extend in rough terrain and comprise different stand structures, which are difficult to discriminate. This paper explores the joint analysis of Landsat7/ETM+, L-band SAR and their derived parameters and the effect of terrain corrections to overcome the challenges of discriminating forest stand age classes in mountain regions. We also verified the performances of three machine learning methods which have recently shown promising results using multisource data; support vector machines (SVM), neural networks (NN), random forest (RF) and one traditional classifier (i.e., maximum likelihood classification (MLC)) as a benchmark. The non-topographically corrected ETM+ data failed to differentiate among different forest stand age classes (average classification accuracy (OA) = 65%). This confirms the need to reduce relief effects prior data classification in mountain regions. SAR backscattering alone cannot properly differentiate among different forest stand age classes (OA = 62%). However, textures and PolSAR features are very efficient for the separation of forest classes (OA = 82%). The highest classification accuracy was achieved by the joint usage of SAR and ETM+ (OA = 86%).
However, this shows a slight improvement compared to the ETM+ classification (OA = 84%). The machine learning classifiers proved t o be more robust and accurate compared to MLC. SVM and RF statistically produced better classification results than NN in the exploitation of the considered multi-source data.

The mineral ore potential of many mountainous regions of the world, like the Kurdistan region of Iraq, remains unexplored. For logistical and sometimes political reasons, these areas are difficult to map using traditional methods. We highlight the improvement in remote sensing geological mapping that arises from the integration of geomorphic features in classifications. The Mawat Ophiolite Complex (MOC) is located in the NE of Iraq and is known for its mineral deposits. The aims of this study are: (I) to refine the existing lithological map of the MOC; (II) to identify the best discriminatory datasets for lithological classification, including geomorphic features and textures; and (III) to identify potential locations with high concentrations of chromite. We performed a Support Vector Machine (SVM) classification method to allow the joint use of geomorphic features, textures and multispectral data of the Advanced Space-borne Thermal Emission and Reflection radiometer (ASTER) satellite. The updated map allowed the identification of a new mafic body and a substantial improvement of the geometry of the known lithological units. The use of geomorphic features allowed for the increase of the overall accuracy from 73% to 79.3%. In addition, we detected chromite occurrences within the ophiolite by applying Spectral Angle Mapping (SAM) technique. We identified two new locations having high concentrations of chromite and verified one of these promising areas in the field. This new body covers ~0.3 km2 and has coarsely crystalline chromite within dunite host rock. The chromium (Cr2O3) concentration is ~8.46%. The SAM and SVM methods applied on ASTER satellite data show that these can be used as a powerful tool to explore ore deposits and to further improve lithological mapping in mountainous semi-arid regions

Es ist kein Abstract vorhanden.

The long-term safety of nuclear waste in a deep geological repository is an important issue in our society. Microorganisms indigenous to potential host rocks are able to influence the oxidation state, speciation and therefore the mobility of radionuclides as well as gas generation or canister corrosion. Therefore, for the safety assessment of such a repository it is necessary to know which microorganisms are present in the potential host rocks (e.g., clay, salt) and if these microorganisms can influence the performance of a repository.
Microbial diversity in potential host rocks for geological disposal of nuclear waste was analyzed by culture-independent molecular biological methods (e.g., 16S rRNA gene retrieval) as well as enrichment and isolation of indigenous microbes.
Among other isolates, a Paenibacillus strain, as a representative of Firmicutes, was recovered in R2A media under anaerobic conditions from Opalinus clay from the Mont Terri in Switzerland. Accumulation experiments and potentiometric titrations showed a strong interaction of Paenibacillus sp. cells with U(VI) within a broad pH range (3-7) [1].
Additionally, the interactions of the halophilic archaeal strain Halobacterium noricense DSM 15987, a salt rock representative reference strain, with U(VI) at high ionic strength was investigated. After 48 h the cells were still alive at uranium concentrations up to 60 μM, which demonstrates that Halobacterium noricense can tolerate uranium concentrations up to this level. The formed uranium sorption species were examined with time-resolved laser-induced fluorescence spectroscopy (TRLFS).
The results about the microbial communities present in potential host rocks for nuclear waste repositories and their interactions with radionuclides contribute to the safety assessment of a prospective nuclear waste repository.

Metal: matrix templates deposited by physical vapor deposition (PVD) were used to grow separated, individual single-walled carbon nanotubes (SWCNTs). The templates are thin films of 2 nm thickness, where the metal is either segregated as nanoparticles (NPs) or diluted in the matrix. The upper limit of the NP diameter was confined by the film thickness. The function of the matrix is to prevent the metal particle from coalescence during nanotube growth by chemical vapor deposition. SEM, TEM, AFM, and Raman mapping were used for template and carbon nanotube characterization. SWCNTs with a narrow, monomodal diameter distribution are obtained from templates with NPs of 2 nm diameter. About 50 % of the SWCNTs detected by Raman mapping have a diameter between 1.3 nm and 1.5 nm. Smaller SWCNT diameters down to 0.8 nm are obtained from templates where the metal is diluted in the matrix. For these templates a bimodal SWCNT diameter distribution was observed. The two maxima of the CNT diameter distribution were found at about 0.8 nm to 1.0 nm and at about 1.2 nm to 1.4 nm, respectively. The CNTs are in their majority separated each from other.

The treatment of loosened total hip replacement (THR) acetabular components may require the management of severe bone defects. Although being applied for decades, there is only limited scientific data about the osteointegration of cancellous bone allografts (CBA) and other void fillers. Monitoring of periprosthetic bone regeneration could possibly help to optimize this process thereby reducing late failure rates. The aim of this study was to show osteometabolic changes in periprosthetic CBA after THR revision with the use of sodium-[18F]-fluoride (NaF) and positron emission tomography (PET). Patients, methods: Twelve patients undergoing THR revision with the use of CBA were prospectively enrolled in the study. Nine patients completed all necessary examinations and were included in the evaluation. The temporal pattern of osteointegration was assessed via NaF-PET at one (PET1) and six weeks (PET2) after surgery. CBA, tantalum implants, supraacetabular regions ipsilateral and contralateral, and parasymphyseal pubic bones were delineated as volumes of interest (VOI) in postop CT scans, which were then merged with the PET data. Results: In comparison to the contralateral supraacetabular reference bone, a significant 1.5-fold increase of osteometabolic activity from PET1 to PET2 was seen in the CBA region. Also, the ipsilateral supraacetabular host bone showed a higher NaF-influx in week 6, compared to the first postoperative week. The supraacetabular site exhibited a significantly 1.8- to 2-fold higher influx and uptake than bone regions in non-operated sites. Tantalum implants had a low NaF influx at both time points investigated.

Conclusion: Using NaF-PET osteometabolic changes of CBA and implant-bone-interfaces can be monitored. Applying this method we demonstrated early periprosthetic temporal bone regeneration patterns in THR cup revision patients.

Nanoparticles represent highly promising platforms for the development of imaging and therapeutic agents, including those that can either be detected via more than one imaging technique (multi-modal imaging agents) or used for both diagnosis and therapy (theranostics). A major obstacle to their medical application and translation to the clinic, however, is the fact that many accumulate in the liver and spleen as a result of opsonization and scavenging by the mononuclear phagocyte system. This focused Review summarizes recent efforts to develop zwitterionic-coatings to counter this issue and render nanoparticles more biocompatible. Such coatings have been found to greatly reduce the rate and/or extent of non-specific adsorption of proteins and lipids to the nanoparticle surface, thereby inhibiting production of the "biomolecular corona" that is proposed to be a universal feature of nanoparticles within a biological environment. Additionally, in vivo studies have demonstrated that larger-sized nanoparticles with a zwitterionic coating have extended circulatory lifetimes, while those with hydrodynamic diameters of <= 5 nm exhibit small-molecule-like pharmacokinetics, remaining sufficiently small to pass through the fenestrae and slit pores during glomerular filtration within the kidneys, and enabling efficient excretion via the urine. The larger particles represent ideal candidates for use as blood pool imaging agents, whilst the small ones provide a highly promising platform for the future development of theranostics with reduced side effect profiles and superior dose delivery and image contrast capabilities.

Es ist kein Abstract vorhanden.

Es ist kein Abstract vorhanden.

Nonlinear 2-dimensional PT-symmetric plaquettes of various types are considered. A technique is developed to obtain explicit matrix representations for the parity (P) and for the time-reversal (T) operators starting from initially heuristically designed gain-loss setups of general 2D-type. The threshold behavior of the corresponding linear sub-systems is analyzed near PT-phase transition points in parameter space, the concrete type of exceptional point is established and the analytical construction of stationary solutions for the nonlinear setups is made explicit. The presentation is based on common work with Panayotis Kevrekidis, Kai Li and Boris Malomed [J. Phys. A 45, 444021 (2012)]. Next possible steps of technical extensions towards higher-dimensional soliton setups and required integrability tests via the search for Lax pairs of Zakharov-Shabat and Fordy-Kulish type are briefly sketched.

Carbonate chimney-like structures up to 60 m high are scattered or arranged in rows at the shores of a desiccating hypersaline and alkaline lake from a continental rift setting (Lake Abhé, Afar Rift, Djibouti). The chimneys apparently formed sub-aqueously in the lake water body at a higher water level than observed today. Alternating calcite and low-Mg calcite + silica concentric layers compose the chimney structures. Mineralogical and geochemical investigations of the chimneys, lake water, and hot spring (hydrothermal) fluids suggest that the chimneys are a result of rapid carbonate precipitation during the mixing of hydrothermal fluids with lake water. In contrast to hot spring fluid, lake water is enriched in HREE and possesses a pronounced positive Ce anomaly, features that are preserved in the carbonate chimney layers. Mixing calculations based on Sr- isotope and concentration data indicate a hydrothermal fluid contribution of ~45 % in the chimney interior, which decreases to ~4 % in the external chimney layer. Sr in the hydrothermal fluids is predominantly leached from the underlying volcanic rocks, whereas the lake’s Sr budget is dominated by riverine input. Considering the fluid mixing ratios calculated by Sr-data, the measured C and O isotope compositions indicate that chimney carbonates precipitated at temperatures between 14°C (internal part) and 22°C (external part) with a carbon source that was most likely atmospheric.
The low-Mg calcite layers, including the outermost layer, appear to have enhanced signals of lake water inheritance based on elevated concentrations of immobile elements, ΣREE, and Sr and Ca isotope compositions. Ca-isotope data reveal that internal chimney layers formed by non-equilibrium calcite precipitation with a predominantly hydrothermal Ca source. The external low-Mg calcite layer received Ca contributions from both hydrothermal fluid and lake water, with the latter being the dominant Ca source. Highly positive δ^44/40Ca of lake water likely reflects non-equilibrium Ca-carbonate precipitation during lake water evaporation with resulting ⁴⁴Ca enrichment of residual lake water. The strong degree of ⁴⁴Ca enrichment may point towards multiple lake drying and Ca-reservoir depletion events. Coupled C-O-Ca-isotope data of the sampled carbonate chimney suggest late-stage (low-temperature) hydrothermal carbonate chimney formation during strongly evaporative lake conditions at the time of low-Mg calcite precipitation. U-Th age dating suggests the chimneys formed no earlier than 0.82 kyr BP (0.28 ± 0.54).

Ziel:

Phosphodiesterasen (PDE) hydrolysieren die zyklischen Nucleotide cAMP und/oder cGMP. PDE-Inhibitoren verzögern den Abbau dieser sekundären Botenstoffe und beeinflussen physiologische Prozesse. Die PDE2A zeigt eine hohe, spezifische Expression im Gehirn sowie in bestimmten Tumoren und ist vermutlich an der Pathophysiologie entsprechender Erkrankungen beteiligt. Ziel ist die Darstellung eines F-18-Radioliganden für die Bildgebung der PDE2A mittels PET.

Methodik:

Ausgehend von der Leitstruktur TA1 wurden neue Fluoralkyl-Derivate TA2-4 entwickelt
(Abb. 1). Für potentielle PDE2A-Inhibitoren ist neben der Affinität v. a. die Selektivität zwischen der PDE2A und der PDE10A aufgrund ähnlicher Verteilungsmuster entscheidend.
Abb. 1
Zu den Derivaten TA3/4 wurden Tosylat-Präkursoren für einstufige F-18-Markierungen synthetisiert, wobei folgend der Radioligand [F-18]TA3 vorgestellt wird.
Die F-18-Fluorierung erfolgte in Acetonitril bei 80°C in 15 Minuten. [F-18]TA3 wurde mittels semi-präparativer HPLC isoliert, über eine Sep-Pak® C18 Kartusche gereinigt und in 0,9%iger NaCl-Lösung formuliert. Die Analytik des Endproduktes erfolgte mittels Radio-DC und -HPLC. Für in-vitro-Autoradiographien wurden sagittale Rattenhirnschnitte mit 1 MBq [F-18]TA3 für 60 Minuten bei Raumtemperatur inkubiert.

Ergebnisse:

[F-18]TA3 wurde mit einer Markierungsausbeute von 75,4 ± 4,9%, einer radiochemischen Ausbeute von 57,2 ± 0,4%, einer spezifischen Aktivität von 60,4 ± 11,6 GBq/µmol (EOS) und einer radiochemischen Reinheit von ≥ 99,5% synthetisiert.
Entsprechend dem PDE2A-Verteilungsmuster zeigten erste in-vitro-Autoradiographien eine hohe und spezifische Anreicherung von [F-18]TA3 im Cortex und Striatum (Abb. 2).

Abb. 2
Schlussfolgerungen:
Die Ergebnisse zu [F-18]TA3 zeigen, dass ein neuartiger und hochaffiner PDE2A-Radioligand erfolgreich dargestellt werden kann. Die Radiosynthese von [F-18]TA4 wird derzeit bearbeitet. Die Charakterisierung dieser F-18-Alkyl-Derivate mittels TierPET/MR, Autoradiographie und Studien zum Metabolismus ist geplant.

The complexation of U(VI) at the proteinaceous surface layer (S-Layer) of the archaeal strain Sulfolobus acidocaldarius was investigated over a pH range from pH 1.5 to 6 at the molecular scale using time-resolved laser-induced fluorescence spectroscopy (TRLFS) and U LIII-edge extended X-ray absorption fine structure (EXAFS). The S-layer, which represents the interface between the cell and its environment, is very stable against high temperatures, proteases, and detergents. This allowed the isolation and purification of S-layer ghosts (=empty cells) that maintain the size and shape of the cells. In contrast to many other cell envelope compounds the studied S-layer is not phosphorylated, which enabled the investigation of uranyl carboxylate complexes, which are usually masked by uranyl phosphate complexes. We demonstrated that at highly acidic conditions (pH 1.5 to 3) no uranium was bound by the S layer. In contrast to that, at moderate acidic pH conditions (pH 4.5 and 6) a complexation of U(VI) at the S layer via deprotonated carboxylic groups was stimulated. Titration studies revealed dissociation constants for the carboxylic groups of glutamic and aspartic acid residues of pKa = 4.78 and 6.31. The uranyl carboxylate complexes formed at the S-layer did not show luminescence properties at room temperature, but only under cryogenic conditions. The obtained luminescence maxima are similar to those of uranyl acetate. EXAFS spectroscopy demonstrated that U(VI) in these complexes is mainly coordinated to carbon in a bidentate binding mode. The elucidation of the molecular structure of these complexes was facilitated by the absence of phosphate groups in the studied S-layer protein.

Interactions of a facultative anaerobic bacterial isolate named Paenibacillus sp. JG-TB8 with U(VI) were studied under oxic and anoxic conditions in order to assess the influence of the oxygen-dependent cell metabolism on microbial uranium mobilization and immobilization. We demonstrated that aerobically and anaerobically grown cells of Paenibacillus sp. JG-TB8 accumulate uranium from aqueous solutions under acidic conditions (pH 2 to 6), under oxic and anoxic conditions. A combination of spectroscopic and microscopic methods revealed that the speciation of U(VI) associated with the cells of the strain depend on the pH as well as on the aeration conditions. At pH 2 and pH 3, uranium was exclusively bound by organic phosphate groups provided by cellular components, independently on the aeration conditions. At higher pH values, a part (pH 4.5) or the total amount (pH 6) of the dissolved uranium was precipitated under oxic conditions in a meta autunite-like uranyl phosphate mineral phase without supplying an additional organic phosphate substrate. In contrast to that, under anoxic conditions no mineral formation was observed at pH 4.5 and pH 6, which was clearly assigned to decreased orthophosphate release by the cells. This in turn was caused by a suppression of the indigenous phosphatase activity of the strain. The results demonstrate that changes in the metabolism of facultative anaerobic microorganisms caused by the presence or absence of oxygen can decisively influence U(VI) biomineralization.

Positron Emission Tomography (PET) is an in vivo molecular imaging tool which is widely used in nuclear medicine for early diagnosis and treatment follow-up of many brain diseases. PET uses biomolecules as probes which are labeled with radionuclides of short half-lives, synthesized prior to the imaging studies. These probes are called radiotracers. Fluorine-18 is a radionuclide that is routinely used in radiolabeling of neuroreceptor ligands for PET because of its favorable half-life of 109,8 min. The administration of such radiotracers into the brain provides images of transport, metaboic and neurotransmission processes on the molecular level. After a short introduction into the principles of PET this talk will mainly focus on the strategy of radiotracer development bridging from basic science to biomedical application. Successful radiotracer design as discussed in this talk provides molecular probes which are not only useful for imaging of human brain diseases. They allow also molecular neuroreceptor imaging studies in various small-animal models of disease including genetically engineerd animals. Futhermore, they provide a powerful tool for in vivo pharmacology during the process of preclinical drug development to identify new drug targets, to investigate pathophysiology, to discover potential drug candidates, and to evaluate the phramacokinetics and pharmacodynamics of drugs in vivo.

Experiments have been undertaken to explore the improvement of the aqueous corrosion and high temperature oxidation of CuZn and TiAl, respectively, by applying plasma immersion ion implantation (PI3).
The atmospheric corrosion of the tongues within the reed pipes which consist of a Cu-Zn alloy (namely brass) is strongly enhanced by traces of VOC (acetic acid vapors) and also the alloy’s instability caused by dezincification. A significant improvement in corrosion resistance has been achieved by applying a 30 nm aluminum oxide film using pulsed laser deposition (PLD) and implanting nitrogen ions into the near surface and the interface regions. In the case of γ-TiAl alloys which exhibit poor oxidation resistance, despite their good mechanical properties at elevated temperatures, this limits the replacement of the nowadays used heavy components made of Ni-alloys. A significant improvement in high temperature oxidation resistance of TiAl alloys (up to 900 °C) has been achieved by implanting fluorine ions (1017 cm-2) at 30 keV into the alloy’s subsurface using PI3 process. A TiAl alloy modified in this way has been shown to acquire a stable, adherent and highly protective alumina scale (Al2O3) under high temperature oxidation in air. The influence of the implanted N+ into CuZn and F+ into TiAl samples on the corrosion process has been investigated. For the sample evaluation, different characterization methods including scanning electron microscope with energy dispersive X-ray spectroscopy (SEM / EDX), Auger electron spectroscopy (AES), Rutherford backscattering spectroscopy (RBS), Elastic recoil detection analysis (ERDA), and Dektak stylus profiling have been applied to determine the chemical composition, the elemental depth profiles, roughness and defect formation of the samples before and after exposure.

The blood-brain barrier (BBB) is a control system to preserve homeostasis in the nervous system, facilitating the entry of necessary metabolites, but blocking the entry or facilitating the removal of unnecessary metabolites or toxic substances. For any solute the efficacy of the exclusion or transport is determined by the morphological and functional characteristics of the brain capillaries and by the biochemical and biophysical characteristics of the solute. This applies also for radiotracers which are used for brain imaging. Several transport routes across the BBB exist. Therfore, the transport of radiotracers depends on the functional status of the brain endothelium. Studies were performed to investigate the expression and function of various transport systems at the BBB, such as ABC transporters, aquaporins, glucose, amino acid, choline and serotonin transporters. The influence of drugs, hormones and brain development on transport processes has been explored. Our main findins are: (1) The brain uptake of certain ^99m/99Tc-labelled radiotracers is reduced by the presence of drug efflux transporters, e.g: P-glycoprotein. (2) Peptide hormones selectively alter the water permeability and the transport of neutral amino acids at the BBB. (3) The BBB transport of neutral amino acids decreases during development. (4) The transport of basic drugs from blood to brain is partly mediated by the BBB choline transporter. (5) The transport of the PET radiotracer [¹¹C]McN5652 is mediated by the serotonin transporter at the BBB but of no relevance for human PET studies. It is concluded that the transport of radiotracers across the BBB does not solely depend on the lipophilicity of the compounds. Active and regulated efflux systems need to be considered. For many radiotracers specific transport systems exist, which underlie developmental changes and physiological regulation. Nutrient transporter, e. g. for glucose, amino acids and choline, are of special importance.

Molecular imaging (MI) originated from the field of radiopharmacology due to the need to better understand the fundamental molecular pathways inside organisms in a noninvasive manner. It emerged in the early twenty-first century as a discipline at the intersection of molecular biology and in vivo imaging and enables the visualization of the cellular function and the follow-up of the molecular process in living organisms without perturbing them. Basic requirements for MI are probes whose concentration and/or spectral properties are altered by the specific biological process under investigation technology to monitor these probes in living organisms and to reconstruct images from their distribution patterns. Positron Emission Tomography (PET) ist the most sensitive molecular imaging tool and a well-established method for neuroimaging of neurodegeneration such as Alzheimer's disease (AD). An ideal PET biomarker for AD should allow a reliable estimation of disease risk and rate of disease progression long before first symptoms are clinically diagnosed. The main pathologic processes of AD, deposition of beta-amyloid, hyperphosphorylated tau protein, degeneration of cholinergic and other neurons, precede clinical symptoms by years providing potential targets for the identification of individuals at risk for AD. In the last few years, several PET tracers targeting beta-amyloid in AD have been developed. The suitability of these PET radiopharmaceuticals to differentiate AD patients and patients with mild cognitive impairment (MCI) from control subjects has been demonstrated and will be discussed. However beta-amyloid deposition has been found in about 20% of normal elderly subjects.

Introduction: Particle Therapy - Positron Emission Tomography (PT-PET) is currently the only clinically applied method for in vivo verication of ion-beam radiotherapy during or close in time to the treatment.
Since a direct deduction of the delivered dose from the measured activity is not feasible, images are compared to a reference distribution. The achievable accuracy of two image analysis approaches was investigated by means of reproducible phantom benchmark tests. This is an objective method that exclude patient related factors of influence.
Material and Methods: Two types of phantoms were designed to produce well dened deviations in the activity distributions. Pure range dierences were simulated using the rst phantom type while the other emulated cavity structures. The phantoms were irradiated with 12C-ions. PT-PET measurements were performed by means of a camera system installed at the beamline. Dierent measurement time scenarios were investigated, assuming a PET scanner directly at the irradiation site or placed within the treatment room.
The images were analyzed by means of the Pearson Correlation Coecient (PCC) and a range calculation algorithm combined with a dedicated cavity lling detection method.
Results: Range dierences could be measured with an error of less than 2 mm. The range comparison algorithm yielded slightly better results than the PCC method. The lling of a cavity structure could be safely detected if its inner diameter was at least 5 mm.
Conclusion: Both approaches evaluate the PT-PET data in an objective way and deliver promising results for in-beam and in-room PET for clinical realistic dose rates.

Polymetallic Cu-Ag ores of the Central European Kupferschiefer deposits are one of the most important sources of Cu in Europe. Because the ores are typically complex and often exceptionally fine-grained the development of efficient alternatives to conventional beneficiation strategies are an important target of current research. Biomining – the use of biological components for metal extraction - may offer solutions that are both efficient and environmentally benign. As conventional bioleaching with acidophilic microorganisms is impeded by the high carbonate content of the Kupferschiefer ores, heterotrophic microorganisms and glutamic acid are investigated as a possible alternative in the present study. The focus of this investigation is solely on the recovery of copper from the Kupferschiefer sensu strictu. Bioleaching experiments were carried out using such material from the Polkowice Mine in Poland. This material is marked by high grade (3.8 wt% Cu), complex ore mineralogy (chalcocite, bornite, chalcopyrite and covellite in significant quantity) and a gangue mineralogy that is rich in carbonate, organic carbon and clay minerals that together form a very fine-grained matrix. (Bio)-leaching experiments yield best results when glutamic acid alone is used – reaching Cu recoveries up to 44 %. Recoveries are consistently lower in experiments in which glutamic acids and microbiological metabolites are both present. The leaching of chalcocite renders the greatest contribution to the Cu recovered to the leach solution in all experiments. It can be concluded that glutamic acid solubilise copper efficiently from Kupferschiefer, mainly from chalcocite.

Method of Time-resolved Laser-induced Fluorescence Spectroscopy (TRLFS) is explained, and illustrated with U(VI) measuring results gained from surface water and soil water samples originated from the area of the former uranium mining heap "Gessenhalde" close to Ronneburg in Eastern Thuringia. Comparative former TRLFS measuring results gained from several uranium mining tailing waters and from further water samples are shown.

Speciation constitutes the basis for actinide complexation studies. These systems can be very complex and challenging especially because of the polynuclear species. An advanced combination of theoretical and experimental methods is proposed here. Continuous wave (CW) and time-resolved laser-induced fluorescence spectroscopy (TRLFS) data of uranyl(VI) hydrolysis were analyzed using parallel factor analysis (PARAFAC). Distribution patterns of five major species were thereby derived under a fixed uranyl concentration (10-5) over a wide pH range from 2 to 11. UV (180 nm to 370 nm) excitation spectra were extracted for individual species. Time-dependent density functional theory (TD-DFT) calculations revealed ligand excitation (water, hydroxo, oxo) in this region and ligand-to-metal charge transfer (LMCT) responsible for luminescence. Thus excitation in the UV is extreme ligand sensitive and highly specific. Combining findings from PARAFAC and DFT the [UO2(H2O)5]2+} cation (aquo complex, 1:0) and four hydroxo complexes (1:1, 3:5, 3:7 and 1:3) were identified. Refined structural and thermodynamical data of uranyl(VI) hydrolysis is thus acquired.

Perspektiven der Geobiotechnologie

Auf der Suche nach umwelt- und ressourcenschonenden industriellen Prozessen richtet sich der Fokus zunehmend auf die Biologie. Unzählige Organsimen haben im Laufe der Evolution vielfältige Mechanismen entwickelt, die sowohl spezifisch als auch effizient sind. Damit reicht der potentielle Anwendungsbereich von antimikrobiellen Oberflächen über Filtration bis hin zu hochempfindlichen Sensoren.

P2X receptors are trimeric ion channels that are activated by ATP and are permeable for the cations Na⁺, K⁺ and Ca²⁺. Seven different subunits exist, which are assembled as homo- or heterotrimers of various stoichiometry.1,2 Polyoxometalates (POMs) are discrete, polynuclear metal-oxo anions of early transition metals in high oxidation states (e. g. W⁶⁺, Mo⁶⁺, V⁵⁺), comprising edge- and corner-shared MO₆ octahedra. They exhibit enormous flexibility with respect to shape, size, composition and charge.3 POMs are relatively large molecules (> 1 nm) and bear several negative charges. In this respect they bear similarity to ATP, which binds to P2X2 and P2X4 in its tetraanionic form (ATP^4-) and to P2X1 and P2X3 possibly also in its dianionic state as a Mg²⁺ complex (MgATP^2-).4 We previously found that certain POMs can inhibit alkaline phosphatase5 and ectonucleotidases,6, 7 enzymes that are capable of hydrolyzing nucleotides such as ATP and ADP. In the present study we investigated whether POMs can interact with P2X receptors. A series of POMs was investigated for their effects to inhibit ATP-induced calcium influx in recombinant 1321N1 astrocytoma cells stably transfected with P2X1, P2X2, P2X3, P2X4 or P2X7 receptors. Several POMs were found to be highly potent inhibitors of P2X receptors with potency in the low nanomolar range. The compounds were found to be non-cytotoxic at pharmacologically active concentrations, whereas some POMs showed cytotoxic effects in an MTT assay at concentrations typically higher than 1 µM.

1 Young, MT (2010), Trends Biochem. Sci. 35: 83-90
2 Torres, GE, Egan, TM, Voigt, MM (1999), J Biol. Chem. 274: 6653-6659
3 Hasenknopf, B (2005), Front Biosci. 10: 275-28
4 Li, M, Silberberg, SD, Swartz, KJ (2013), Proc. Natl. Acad. Sci. USA: 110: E3455-E3463
5 Raza, R, Matin, A, Sarwar, S, Barsukova-Stuckart, M, Ibrahim, M, Kortz, U, Iqbal, J (2012), Dalton Trans. 41: 14329-14336
6 Müller, CE, Iqbal, J, Baqi, Y, Zimmermann, H, Röllich, A, Stephan, H (2006), Bioorg. Med. Chem. Lett. 16: 5943-5947
7 Stephan, H, Kubeil, M, Emmerling, F, Müller, CE (2013), Eur. J. Inorg. Chem. 1585-1594

In Europe, most of the primary copper resources that possess a high or moderate amount of metals, have a reasonable accessibility and are easy to process are exhausted. In this context, low grade and complex ores as well as old waste deposits related to past mining activities are receiving increasing attention. For an economic exploitation of such ores and resources, with quite different mineral matrix, new and efficient methods need to be developed. Bioleaching is a reliable and promising option .
Among the different kinds of copper mineralisation that can be found in Europe, sulphidic Kupferschiefer deposits have been explored and exploited for years in Germany and Poland. They are Europe’s largest copper reserve with more than 60 Mill. tons of Cu, and contain additional associated metals such as Ag, Pb, Zn and possibly other high-value metals. Kupferschiefer deposits are currently under exploitation in Poland, but process operations are more and more penalised by the significant amounts of organic matter and arsenic present in this type of ores. Therefore bioleaching is more and more considered as a credible alternative to the pyrometallurgical technology which may no longer be feasible in future given the concentrate chemistry.
In this context, this paper provides an overview of the previous work on the geology, mineralogy, and (bio)processing of the Kupferschiefer. It will also present new opportunities and challenges related to the development of innovative methods for metal recovery by means of biotechnology.
Generally, bioleaching of Kupferschiefer is influenced by the mineralogical nature of sulphides and organic matter contained in the ores. For example, recalcitrance of chalcopyrite during leaching is a major limitation of biohydrometallurgy applied to copper ores in general and blackshales in particular. Organic matter, moreover, causes also flotation problems. However, the organic materials especially the metallorganic compounds containing platinum group (PGE) or rare earth elements (REE) may make processing of Kupferschiefer economically interesting.
The first works dealing with Kupferschiefer bioleaching in Europe date back more than three decades, and were pursued again beginning of the 21st century in the European Bioshale project. This project demonstrated the overall efficiency of continuous stirred tank reactors (CSTR) bioleaching of a blackshale concentrate with an extraction rate above 90 %. Nevertheless, two possible improvement paths were identified: reducing the tank size or improving chalcopyrite dissolution affecting the operation efficiency. These challenges were then further addressed in ProMine project opening new perspectives for bioleaching of Kupferschiefer ores which will be dealt with in the French-German project Ecometals.

Punctual occurrence phenomena are often modeled as Poisson point processes, sometimes with an inhomogeneous, unknown intensity, that is desired to be estimated from some covariables. Within this setting, we study the case in which the covariables form a regionalized geochemical composition of stream sediments, and the known punctual occurrences are existing mineral deposits, not collocated with the available explanatory data. This is modeled by assuming a two-layer stochastic process, where the observed Poisson log-intensity is taken as a balanced log-linear function of the geochemical composition of stream sediments, which coefficients must be estimated. Estimation is possible through a pseudolikelihood device based on generalized loglinear models, though the result intensity function appears to be valid only up to arbitrary scaling and addition of constants.

Compositional data occur in all fields of science: from politics to materials engineering, from biomedical sciences to geochemistry. In all these fields, variables representing the relative contribution of some parts forming a whole are routinely acquired. Actually, compositions form their own scale, essentially characterized by their intrinsic multivariate nature and the closure to constant sum to 100%. Statistical techniques used with these data must then conform to that scale.

This contribution presents a comprehensive summary of how to adapt the most common statistical techniques, based on the principle of working on coordinates within the log-ratio approach. In application of this principle, data are represented in an one-to-one set of logratios of the original components, the scores are analysed with classical multivariate tools, and results are eventually back-transformed for interpretation. In particular, this contribution explores the uses of cluster analysis, principal components and linear regression to explain the natural variability on several data sets from the Earth sciences.

Spurious correlation is known to be a problem in statistics since Pearson's early warnings in 1897. The same problems arise in spatial statistics: bias towards negative values and non-zero cross-covariances and cross-covariograms; singular matrices of intrinsic co-dispersion; co-kriged regionalised vectors of proportions that do not satisfy the constant sum constraint. A way out is to use log-ratio transformations: the spatial structure can be described in terms of direct variograms of each possible pairwise logratio; variation-variograms can be estimated even in case of missing components; they can be modelled with standard tools; both the data and the spatial structure model can be expressed in isometric logratio coordinates, and standard co-kriging techniques can be applied to obtain interpolated logratios. These can be back-transformed to compositions, delivering interpolated maps of each component that satisfy the required constraints. Moreover, the result does not depend on which logratio transformation was used for the computations. This approach and its potentialities is illustrated with a data set of soil geochemistry.

The development of multi-functional complexing agents for radiometal nuclides with a view of nuclear medical application represents a fast developing field of intensive research [1]. A requirement for ligands in this field is fast complexation kinetics and high complex stabilities with specific radiometal ions and ligands which are easy to functionalize with several different groups for linking to biological vectors, nanoparticles and/or fluorescence molecules.

Ligands based on 3,7-diazabicyclo[3.3.1]nonane (bispidine) form very stable transition metal complexes [2]. Due to the formation of thermodynamically and kinetically stable Cu^II complexes, pentadentate and hexadentate bispidines are very well suited for in vivo application, i.e. for tumor imaging (⁶⁴Cu^II) using positron emission tomography (PET) and tumor therapy (⁶⁴Cu^II, ⁶⁷Cu^II) [3, 4]. The bispidine scaffold has various sites for functionalization that permit the introduction of biomolecules for pharmaceutical targeting and fluorescent units for optical imaging (see Figure 1).

Several bispidine ligands have been developed in order to improve the radiopharmaceutical behavior as well as possibilities for further beneficial functionalization. These ligands and the important properties of their Cu^II complexes, e.g., stabilities, ligand exchange kinetics, serum stability, partition coefficients ([⁶⁴Cu]Cu-bispidine: n-octanol/water) and biodistribution studies ⁶⁴Cu-labeled bispidines will be reported.

References
1. C. S. Cutler, M. H. Hemmkens, N. Sisay, S. Markai-Huclier. S. S. Jurisson, Chem. Rev. 113, 858 (2013).
2. P. Comba, M. Kerscher, W. Schiek, Prog. Inorg. Chem. 55, 613 (2007).
3. S. Juran, M. Walther, H. Stephan, R. Bergmann, J. Steinbach, W. Kraus, F. Emmerling, P. Comba, Bioconjugate Chem. 20, 347, (2009).
4. P. Comba, S. Hunoldt, M. Morgen, J. Pietzsch, H. Stephan, H. Wadepohl, Inorg. Chem. 52, 8131 (2013).

ken Abstract verfügbar

The use of nanoparticles in multimodal bio-imaging is attracting increasing interest, but toxicity and accumulation in organs still limit their in vivo applications. Silicon nanoparticles (Si NPs) are very promising in this respect as their size, 1.5 - 4 nm, can allow body excretion. In addition Si NPs are photo- and chemical stable, possess bright tunable luminescence and can be covalently functionalized with desired molecules. Indeed several techniques have been described to obtain Si NPs [1-3] with different sizes and bearing various functional groups.
Here we report on some optimized wet chemistry techniques to prepare ultrasmall (< 5 nm) Si NPs and, in particular, the focus is on microemulsion methods and hydrothermal synthesis. The obtained Si NPs can bear different functional groups, allowing a wide spectrum of subsequent conjugations. Once functionalized and purified, Si NPs were characterized by HR-TEM and IR spectroscopy, and their photophysical properties were investigated. Reactivity and properties of the NPs obtained by various methods will be compared and the results of in vitro and in vivo experiments will be shown to demonstrate the great potentialities of such ultrasmall Si NPs.
This work was financially supported by Helmholtz Virtual Institute “Nano-Tracking”, Agreement No. VH-VI-421

1. J. H. Warner et al., Angew. Chem. Int. Ed. 2005, 44, 4550 –4554
2. M. Rosso-Vasic et al., Small, 2008, 4, 1835–1841
3. Y. Zhong et al., J. Am. Chem. Soc., 2013, 135, 8350-8356

Unipolar resistive switching in YMnO₃ with large-scale bottom and small-scale top electrodes is analyzed in detail by tracking the morphological transformations of the top electrodes induced by applied writing voltages. Micro-scale digital images are taken after each subsequent quasi-static current-voltage sweep. Current mapping after electrical investigations indicates a shift in the conductivity at the localized areas of the morphologically transformed top electrodes. Those changes are assigned to the heat induced structural and compositional changes within YMnO₃ which lead to the formation and rupture of conductive filaments observed as unipolar resistive switching. Presented results underline the importance of Joule heating in the fostering of resistive switching and its adverse impact on the device endurance.

Microelectronics today is still based on the silicon technology it has been employing for the past 40 years even though it has been highly optimised and iteratively refined. Yet, it will come to a point where new concepts will be needed when “More Moore” has been extended to its ultimate limits. This is why there is a high interest in researching different approaches, e.g., with added functionality (“More-than-Moore”) [1] or even completely different concepts going “beyond Moore” like molecular electronics.

In the first part of this paper we present recent work on the top-down fabrication of silicon nano wire field effect transistors (FET) with two gates allowing not only for the control of the current through the device as it is done in a conventional FET but also to switch between the conduction mechanism, i.e., p- or n-type behaviour. It has been demonstrated previously that this kind of device can be used to build circuits [2,3]. However, we want to extend the principle from single nano wire devices to complex integrated circuits.

The second part will then go “beyond Moore” to illustrate results from our research on two challenges in the field of molecular electronics: Joining bottom-up with top-down techniques to form electrical contacts to nano objects on the one hand. We employ ion beam treatment of the substrate to form a preferential alignment for DNA templated wires. These will ultimately be used for DNA templated quantum dot transistors. On the other hand we will present a single molecular switch sensitive to light in the UV/VIS regime [4].

[1] ITRS “More-than-Moore” White Paper (2010) – http://www.itrs.net/papers.html
[2] A. Heinzig et al., Nano Lett. 12 (1) 119–124 (2012)
[3] T. Mikolajick et al., Phys. Status Solidi Rapid Res. Lett. 7 (10), 793–799
[4] Y. Kim et al., Nano Lett. 12 (7) 3736–3742 (2012)

We present an adaptive Monte Carlo approach for computing the amplified spontaneous emission (ASE) flux in large size laser gain media pumped by pulsed lasers. Computations are based on a GPU algorithm with large speedup compared to previously existing solutions, capable of simulating the upcoming generation of high-power laser systems.

We present an adaptive Monte Carlo approach for computing the amplified spontaneous emission (ASE) flux in a laser medium pumped by pulsed lasers. For high energy laser systems with large apertures sufficient spatial resolution requires high computational power. We have developed an adaptive multi-node GPU algorithm with load balancing that shows close to perfect strong scaling that allows for large speedups compared to previously existing CPU implementations. This code will allow to calculate the ASE flux in large size gain media as they will be used in the upcoming generation of high-power laser systems.

The lanthanide and actinide elements are exogenous metals, which have no essential role in normal biochemistry. Through different processes these heavy metals can be potentially released into the environment where they can be incorporated into the food chain. There are executed Laser-Fluorescence measurements to possible complexes of Eu(III) in body fluids of the human gastrointestinal tract.

The well examined uranium mining waste piles Königstein (Germany) is heavily polluted with uranium and also other toxic metals. Despite it is a reservoir for a high diversity of microorganisms that have evolved special strategies to survive in these extreme environments. Microorganisms are the beginning of the food chain and therefor the transfer of bound uranium along this food chain could rise to a serious threat to human health. The aim of the study should be to characterize the quantitative and structural interactions of different microorganisms with uranium in environmental concentrations and pH ranges. Bodo saltans a eukaryotic flagellate and it´s feeder bacterium Acidovorax facilis should be the representatives of this biodiversity.

The contactless inductive flow tomography (CIFT) aims at reconstructing the velocity field of electrically conducting fluids, with special focus on applications in metallurgy and crystal growth technologies The method relies on the induction of secondary magnetic fields if the moving fluid is exposed to a primary magnetic field. The theoretical foundation of the method is delineated, and some early experiments on the reconstruction of the three-dimensional flow in a cylinder are sketched. Then, the recent efforts to apply CIFT to various model problems in connection with the continuous casting of steel are summarized.

Gemäß verschiedenen Ausführungsformen kann ein komplementärer Widerstandsschalter aufweisen: zwei äußere Kontakte (T1, T2 ), zwischen denen zwei piezo- oder ferroelektrische Schichten (11a und 11b) liegen, die durch einen inneren gemeinsamen Kontakt voneinander getrennt sind, dadurch gekennzeichnet, dass mindestens ein Bereich der piezo- oder ferroelektrischen Schicht (11a und 11b) mindestens einmal derart modifiziert ist, dass in der piezo- oder ferroelektrischen Schicht (11a und 11b) jeweils zwischen dem inneren Kontakt und dem zugehörigen äußeren Kontakt ein Bereich (11') der Dicke (d ') entsteht, weicher mindestens zusätzlich in einem Bereich (11") der Dicke (d") modifiziert sein kann, wobei a) die äußeren Kontakte Oberflächenkontakte (Sa) und (Sb) und der innere Kontakt ein gemeinsamer zugehöriger Gegenkontakt (O) oder die äußeren Kontakte Gegenkontakte (Oa) und (Ob) und der innere Kontakt ein gemeinsamer zugehöriger Oberflächenkontakt (S) sind, b) die Oberflächenkontakte (S), (Sa) und (Sb) gleichrichtend und die Gegenkontakte (O) bzw. (Oa) und (Ob) nicht-gleichrichtend sind, c) sich die modifizierten Bereiche in der piezo- oder ferroelektrischen Schicht (11a und 11b) an den Oberflächenkontakten (S) bzw. (Sa) und (Sb) ausbilden, d) die piezo- oder ferroelektrische Schichten (11, 11', 11") verschiedene verspannungsabhängige strukturelle Phasen mit unterschiedlicher Bandlücke und/oder unterschiedlicher Polarisationsladung aufweisen, und e) die elektrische Leitfähigkeit der piezo- oder ferroelektrischen Schichten (11, 11', 11") unterschiedlich ist.

Introduction
(−)-[¹⁸ F]Flubatine is a PET tracer with high affinity and selectivity for the nicotinic acetylcholine α4β2 receptor subtype. A clinical trial assessing the availability of this subtype of nAChRs was performed. From a total participant number of 21 Alzheimer’s disease (AD) patients and 20 healthy controls (HCs), the following parameters were determined: plasma protein binding, metabolism and activity distribution between plasma and whole blood.

Methods
Plasma protein binding and fraction of unchanged parent compound were assessed by ultracentrifugation and HPLC, respectively. The distribution of radioactivity (parent compound + metabolites) between plasma and whole blood was determined ex vivo at different time-points after injection by gamma counting after separation of whole blood by centrifugation into the cellular and non-cellular components. In additional experiments in vitro, tracer distribution between these blood components was assessed for up to 90 min.

Results
A fraction of 15% ± 2% of (−)-[¹⁸F]Flubatine was found to be bound to plasma proteins. Metabolic degradation of (−)-[¹⁸F]Flubatine was very low, resulting in almost 90% unchanged parent compound at 90 min p.i. with no significant difference between AD and HC. The radioactivity distribution between plasma and whole blood changed in vivo only slightly over time from 0.82 ± 0.03 at 3 min p.i. to 0.87 ± 0.03 at 270 min p.i. indicating the contribution of only a small amount of metabolites. In vitro studies revealed that (−)-[¹⁸F]Flubatine was instantaneously distributed between cellular and non-cellular blood parts.

Discussion
(−)-[¹⁸F]Flubatine exhibits very favourable characteristics for a PET radiotracer such as slow metabolic degradation and moderate plasma protein binding. Equilibrium of radioactivity distribution between plasma and whole blood is reached instantaneously and remains almost constant over time allowing both convenient sample handling and facilitated fractional blood volume contribution assessment.

An extended study of metallic bonding material for internally cooled optics is presented. The study shows the influence of the different material properties on the final quality of the bond in terms of diffracted wave-front distortion, i.e. enlargement of the rocking curve. By choosing the proper bonding material and applying the proper bonding conditions, the influence of the bonding material can be fully eliminated. Furthermore the degradation of some bonding material due to the extreme working conditions of the optics is presented. Measurement results from ESRF and KEK confirm the importance of the proper bonding material choice.

The flow induced by a single-phase alternating magnetic field (AMF) is studied mainly numerically, and by experiments at mains frequency. For validation, the well-known dependence of the characteristic velocity uc on the magnetic induction B in the turbulent case when the mean velocity scales with the shear velocity, υc ∝ B, is reproduced experimentally and in the simulations. Ultrasonic flow mapping reveals that the eddies in the well believed flow structure of two toroidal vortices one on top of another do not only simply oscillate, but rather the topology of the flow changes slowly on a large scale. Besides such turbulence characteristics, it will be shown that the global flow structure depends strongly also on the frequency of the AMF. An investigation of the change of the characteristic velocity with frequency suggests a quantitative difference of flows in an AMF compared to rotating and travelling magnetic fields.

Quasi-planar morphological surfaces may become dissected or degraded with time, but still retain original features related to their geologic-geomorphic origin. To decipher the information hidden in the relief, recognition of such features is required, possibly in an automated manner. In our study, using Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM), an existing algorithm has been adapted to recognize quasi-planar features fulfilling specified criteria. The method has been applied to a study area of the Central Andes with Miocene to Quaternary volcanic edifices, tilted ignimbrite surfaces, and basin-filling sediments. The result is a surface segmentation, whereas non-planar features (gullies, tectonic faults, etc.) are sorted out. The main types of geomorphic features that can be distinguished and interpreted are as follows. (1) The west-dipping western margin of the Altiplano is differentiated into segments of the lower sedimentary cover that of increased erosion by tectonic steepening at intermediate levels, and an upper plane with limited erosion. (2) In the central part of the Western Cordillera, the Oxaya ignimbrite block shows a ‘striped’ bulging pattern that results from a smoothly changing surface dip. This pattern is due to continuous folding/warping of the ignimbrite block possibly related to gravitational movements. (3) To the west, large, uniform planes correspond to flat, smooth, tectonically undisturbed surfaces of young sedimentary cover of the Central Basin. (4) The evolution of Taapaca volcanoes with sector collapse events and cone-building phases is shown by several segments with overlapping clastic aprons. (5) To the east, on the western margin of the Altiplano, young intermontane basins filled by Upper Miocene sediments show progressively increasing dip toward basin margins, reflected by a circular pattern of the segmentation planes. We show that the segmentation models provide meaningful images and additional information for geomorphometric analysis that can be interpreted in terms of geological and surface evolution models.

Experiments have been undertaken to explore the improvement of the aqueous corrosion and high temperature oxidation of CuZn and TiAl, respectively, by applying plasma immersion ion implantation (PI3).
The atmospheric corrosion of the tongues within the reed pipes which consist of a Cu-Zn alloy (namely brass) is strongly enhanced by traces of VOC (acetic acid vapors) and also the alloy’s instability caused by dezincification. A significant improvement in corrosion resistance has been achieved by applying a 30 nm aluminum oxide film using pulsed laser deposition (PLD) and implanting nitrogen ions into the near surface and the interface regions. In the case of γ-TiAl alloys which exhibit poor oxidation resistance, despite their good mechanical properties at elevated temperatures, this limits the replacement of the nowadays used heavy components made of Ni-alloys. A significant improvement in high temperature oxidation resistance of TiAl alloys (up to 900 °C) has been achieved by implanting fluorine ions (1017 cm-2) at 30 keV into the alloy’s subsurface using PI3 process. A TiAl alloy modified in this way has been shown to acquire a stable, adherent and highly protective alumina scale (Al2O3) under high temperature oxidation in air. The influence of the implanted N+ into CuZn and F+ into TiAl samples on the corrosion process has been investigated. For the sample evaluation, different characterization methods including scanning electron microscope with energy dispersive X-ray spectroscopy (SEM / EDX), Auger electron spectroscopy (AES), Rutherford backscattering spectroscopy (RBS), Elastic recoil detection analysis (ERDA), and Dektak stylus profiling have been applied to determine the chemical composition, the elemental depth profiles, roughness and defect formation of the samples before and after exposure.

Salt rock is one of the three potential host rock types for long-term storage of radioactive waste in a deep geological repository in Germany. To date little is known about the interactions of halophilic microorganisms which are indigenous in salt rock and radionuclides under these extreme conditions. The microorganisms can impact the oxidation state, speciation and solubility of radionuclides and hence their mobility. These information are necessary to improve the safety assessment of a geological repository.
To characterize the interactions between radionuclides and microorganisms under high saline conditions biosorption experiments with Halobacterium noricense DSM 15987 and uranium were done. This halophilic archaea is used because of its ubiquitous occurrence in salt rock [1] .
Due to its halophilicity the working concentration of NaCl was 3 M. The batch experiments have shown that 90% of U(VI) was bound to the cells after 48 h. The formed uranium complexes were characterized by the use of infrared-spectroscopy and time-resolved laser-induced fluorescence spectroscopy (TRLFS). Despite the high concentration of chloride a luminescence spectrum could be recorded. The spectra of the salt solutions (3 M NaCl) with different uranium concentrations (10 µM, 50 µM, 100 µM; pH 6) without cells have the same emission maxima (512, 536, 560 nm; see Fig.1). Comparing the position of this bands with literature they can be assigned to the (UO2)3(OH)5+ complex [2]. In contrast, the suspension consisting of Halobacterium noricense cells and U(VI) in 3 M NaCl lead to a red-shift of the spectra where the emission bands (501, 522, 550 nm; see Fig. 1) indicate the uranyl phosphate complex UO2PO4- [3]. It can be concluded that uranium binds to phosphate groups which are located on the cell wall or inside the cells. Further investigations (e.g. TEM/EDX) are required for differentiation. These first results show that the characterization of the formed complexes is possible with TRLFS despite the high chloride concentration and can be used for further examinations.

1. Swanson, J.S., et al. (2012) Status Report Los Alamos National Laboratory
2. Moulin, C., et al. (1998) Appl. Spectrosc. 52, 528-535.
3. Bonhoure, I., et al.(2007) Radiochim. Acta. 95, 165-172.

Undoped ZnO films are grown by pulsed laser deposition on c-plane sapphire with different Oxygen pressures. Thermal evolutions of defects in the ZnO films are studied by secondary ion mass spectroscopy (SIMS), Raman spectroscopy, and positron annihilation spectroscopy (PAS), and with the electrical properties characterized by the room temperature Hall measurement. Oxygen deficient defect related Raman lines 560 cm^-1 and 584 cm^-1 are identified and their origins are discussed. Thermal annealing induces extensive Zn out-diffusion at the ZnO/sapphire interface and leaves out Zn-vacancy in the ZnO film. Two types of Zn-vacancy related defects with different microstructures are identified in the films. One of them dominates in the samples grown without oxygen. Annealing the sample grown without oxygen or growing the samples in oxygen would favor the Zn-vacancy with another microstructure, and this Zn-vacancy defect persists after 1100 °C annealing.

By implanting Zn+ ions into research-grade intentionally undoped ZnO single crystal for facilitating Zn interstitials (Zni) and O vacancies (VO) which is revealed by precise X-Ray diffraction rocking curves, we observe an apparent broad red luminescence band with a nearly perfect Gaussian lineshape. This red luminescence band has the zero phonon line at ~2.4 eV and shows distinctive lattice temperature dependence which is well interpreted with the configurational coordinate model. It also shows a low “kick out” thermal energy and small thermal quenching energy. A “selfactivated” optical transition between a shallow donor and the defect center of Zni-VO complex or VZnVO di-vacancies is proposed to be responsible for the red luminescence band. Accompanied with the optical transition, large lattice relaxation simultaneously occurs around the center, as indicated by the generation of multiphonons.

Two German ferritic pressure vessel steels are examined in the brittle to ductile transition regime as a function of temperature and irradiation.The experiments are done by a miniaturized Small-Punch-Test in hot cells within the temperature range of -185 °C up to 70 °C. From the load–displacement curve of the SPT,the yield curves and parameters of both a non-local GURSON-TVERGAARD-NEEDLEMAN ductile damage model and a modified BEREMIN model are identified. The influence of temperature and irradiation on the model parameters is analyzed. All parameters are verified by comparison with results from standard test methods. The parameters, identified from SPT, are used to simulate the failure behavior in standard fracture mechanics specimens.In the uppershelf, the non-local GTN-model is applied to simulate crack resistance curves,from where the fracture toughness data could be successfully predicted. In the lower shelf, the WEIBULL-stress of the specimens was computed to find out the statistics of fracture toughness values.Finally, the modified BEREMIN model and the non-local ductile damage model were combined to evaluate the failure of fracture specimens in the brittle-ductile transition region.This way, an acceptable agreement with Master-Curve data for non-irradiated steels could be achieved in the whole temperature range.

The main goal of the current research project is numerical investigation of steam condensation on a subcooled water interface. The Direct Numerical (DNS) and Large Eddy Simulation (LES) methods are used to study physical mechanisms determining the interfacial heat and mass transfer. The paper presents a part of this work that deals with the evaluation of the Sub-Grid Scale (SGS) modeling within the LES framework. For that purpose two simulations of a stratified turbulent counter-current steam-water flow in a channel were conducted using the Wall-Adapting Local Eddy-Viscosity (WALE) SGS model. To exclude the phase change and to focus on the turbulence in the vicinity of the interface, both phases were assumed to be at saturation tem-perature. The simulations have shown that the variation of the WALE model constant has a significant influence on the mean velocity and velocity fluctuations and should be calibrated using the DNS data. It was also shown that the deformable steam-water interface has a strong damping effect on the near-interfacial turbulent field in the liquid phase.

93Zr with a half-life of 1.6 Ma is produced with high yield in nuclear fission, and thus should be present as a natural or anthropogenic trace isotope in all compartments of the general environment. This isotope would immediately find numerous applications, however, its detection at sufficiently low levels has not yet been achieved. AMS measurements of 93Zr suffer from the interference of the stable isobar 93Nb. At the Vienna Environmental Research Accelerator VERA a new multi-anode ionization chamber was built. It is optimized for isobar separation in the medium mass range and is based on the experience from AMS experiments of 36Cl at our 3MV-facility. The design provides high flexibility in anode configuration and detector geometry. After validating the excellent energy resolution of the detector with 36Cl, it was recently used to study Iron-Nickel and Zirconium-Niobium-Molybdenum isobar separation. To our surprise, the separation of 94Zr (Z=40) from 94Mo (Z=42) was found to be much better than that of 58Fe (Z=26) from 58Ni (Z=28), despite the significantly larger deltaZ/Z of the latter pair. This clearly contradicts results from SRIM-simulations and suggests that differences in the stopping behavior may unexpectedly favor identification of 93Zr. At 24 MeV particle energy, a 93Nb (Z=41) suppression factor of 1000 was achieved based on a 93Zr spectrum obtained by interpolation between experimental spectra from the two neighboring stable isotopes 92Zr and 94Zr. Assuming realistic numbers for chemical Niobium reduction, a detection level of 93Zr/Zr below 10^9 seems feasible.

Monte Carlo Simulations have been carried out to estimate the gamma radiation distributions outside the reactor pressure vessel of a generic pressurized water reactor for a set of simplified accident-like reactor states.
This is done as a first step towards the development of a non-invasive core monitoring system for light water reactors.
The results show a change in the shape of the gamma ray distributions for decreasing coolant levels as well as a vast increase in flux for corium accumulating inside the lower head.

The gamma radiation emitted by a nuclear reactor core might contain information about the reactor state. This information may be used in a monitoring system for severe accidents.
The Technische Universit¨at Dresden and the Zittau/G¨orlitz University of Applied Sciences are currently carrying out feasibility studies for the development of such a system in a collaborative effort. As one part of such feasibility studies we performed Monte Carlo simulations on a simplified model of a generic pressurized water reactor. For a set of states which represent scenarios of a coolant level decrease and core melt, the gamma radiation distribution outside the reactor pressure vessel has been computed.
The results are presented in this paper.
They indicate that different coolant levels yield different gamma radiation distributions, and that an accumulation of corium inside the lower head is detectable from the outside.

In this paper the development and implementation of a novel amplifier setup as an additional stage for the CPA pump laser of the Petawatt Field Synthesizer, currently developed at the Max-Planck-Institute of Quantum Optics, is resented. This amplifier design comprises 20 relay-imaged passes through the active medium which are arranged in rotational symmetry. As the gain material, an in-house-developed Yb:YAG active-mirror is used. With this setup, stretched 4 ns seed pulses are amplified to output energies exceeding 1 J with repetition rates of up to 2 Hz. Furthermore, a spectral bandwidth of 3.5nm (FWHM) is maintained during amplification and the compression of the pulses down to their Fourier-limit of 740 fs is achieved. To the best of our knowledge, this is the first demonstration of 1TW pulses generated via CPA in diode-pumped Yb:YAG.

The aim of this talk is to explain method of fabrication, modification and optimization of Sponge-like Si-SiO2 nanocomposite.
It consists of Si embedded in SiO2 fabricated by spinodal decomposition of sputter-deposited silicon-rich oxide SiOx≈1. Thermal treatment using rapid thermal processing and oven annealing requires annealing times of few tens of sec. up to few tens of min. However, in a thin film technology the phase separation of SiOx at high temperatures requires a very rapid thermal processing of few tens of ms in order to avoid substrate damage.
Here, the structure of the Si-SiO2 nanocomposite was investigated by energy-filtered transmission electron microscopy (EFTEM), EFTEM tomography and atom probe tomography, which revealed a percolated Si morphology. This is in excellent agreement with atomistic simulations using kinetic Monte-Carlo method. Depending on the annealing time and temperature a feature size in the range of 2...5 nm was found, which is small enough for band gap widening due to quantum confinement.
We show that the favorable properties of Si-SiO2 nanocomposite, e.g. quantum size effect and percolated morphology, make it a suitable material for PV absorber.

Direct measurements of the vector turbulent emf in a driven two-vortex flow of liquid sodium were performed in the Madison Dynamo Experiment [K. Rahbarnia et al., Astrophys. J. 759, 80 (2012)]. The measured turbulent emf is anti-parallel with the mean current and is almost entirely described by an enhanced resistivity, which increases the threshold for a kinematic dynamo. We have demonstrated that this enhanced resistivity can be mitigated by eliminating the largest-scale eddies through the introduction of baffles. By tailoring the flow to reduce large-scale components and control the helical pitch, we have reduced the power required to drive the impellers, doubled the magnetic flux generated by differential rotation, and increased the decay time of externally applied magnetic fields. Despite these improvements, the flows remain sub-critical to the dynamo instability due to the reemergence of turbulent fluctuations at high flow speeds.

In the first part of the paper, experimental results for the Xe depletion in the matrix of high burn-up fuel are analysed from the High Burnup Rim Project (HBRP). The influence of the burn-up and irradiation temperature on the Xe concentration was investigated using a multi-physics approach involving various simulation tools. The temperature influence was accounted for by means of the temperature dependent effective burn-up. Good agreement was found between the modelled temperature threshold of the effective burn-up and the experimental temperature threshold between un- and restructured fuel in the HBRP. However, a systematic difference was observed between the onset burn-up derived from the Xe measurements in highly enriched discs such as those of HBRP and the corresponding values derived from irradiated Light Water Reactor fuel rods and reported in the open literature. A sensitivity study identified the neutron flux spectrum and the fission product yields as the main reasons for the observed differences.

In the second part of the paper, we present a new model for dealing with release of fission gas from nuclear fuel containing a high burnup structure (HBS) during design basis accidents such as loss of coolant accident. The fission gas release from the HBS during an accident is assumed to be caused by crack formation. The empirical model is developed on the basis of out-of-pile annealing tests carried out with samples from HBRP discs irradiated in Halden, and then subsequently applied to an integral in-pile test in IFA-650. In addition to the comparison with the experimental data, the new model is also compared with some models available in the open literature. Finally, from the discussion we also outline the experimental and modelling work needed for further model refinements.

Fragestellung.
Untersucht wurde die Verteilung der Aktivitätskonzentration des Hypoxietracers FMISO in sequentiellen PET-Untersuchungen bei Patienten mit primär radiochemotherapierten Kopf-Hals-Tumoren. Patienten mit residueller Hypoxie während der zweiten Behandlungswoche erleiden fast immer ein Lokalrezidiv im Hochdosis-Bereich. Zur Erhöhung der Strahlendosis werden unter anderem FMISO-PET-basiert adaptierte Dosisverschreibungen (Dose-painting) diskutiert. Für eine erste Plausibilitätsprüfung dieses Ansatzes wurde die Stabilität der FMISO-Verteilung und die Lokalisation von Lokalrezidiven mit, während der Therapie erfassten, PET-Parametern untersucht.
Methodik.
Von 25 Patienten, die während der primären Radiochemotherapie sequentielle FMISO Aufnahmen erhielten (FMISO1 vor Therapie, FMISO2 in der ersten, FMISO3 in der zweiten und FMISO4 in der fünften Woche) zeigten 12 eine ausgeprägte residuelle Hypoxie (bestimmt als TBR_max>1,9). Sechs dieser Patienten hatten ein auswertbares Lokalrezidiv (2 x in der CT und 4 x in der FDG-PET-CT). Die Rezidivbildgebung und darauf basierende Konturen wurden auf die FMISO- und FDG PET-Untersuchungen vor Therapie fusioniert und die PET-Konturen auf ein Überlappen überprüft.
Ergebnis.
Die wiederholten FMISO-PET-Untersuchungen während der Radiochemotherapie zeigten ein sehr heterogenes volumetrisches Verhalten der hypoxischen Subvolumina zu Beginn der Therapie. In der FMISO4-Bildgebung war nur noch selten Hypoxie nachzuweisen. Trotz der Größenvariationen innerhalb der ersten beiden Wochen war die Überlappung der sequentiellen Sub-Volumina ausgeprägt, bestimmt als mittlerer Dice-Index von 62% zwischen FMISO1 und FMISO2 und 58% zwischen FMISO2 und FMISO3. Die Lokalisation des Aktivitäts-Hot-Spots SUV_max zeigte demgegenüber dramatische Veränderungen, der mittlere Abstand betrug zwischen FMISO2 und FMISO3 13,5
mm. Die vorhandenen, registrierten Rezidive zeigten sowohl ein Überlappen mit dem initialen FDG-PET, als auch mit FMISO1 und FMISO3 (medianer Dice-Index 27, 24 und 28%). Zur Überprüfung ob es wirklich eine reproduzierbare und stabile FMISO-PET-positive Region gibt, die sich zur Dosiseskalation eignet, wurden die überlappenden Konturen verschiedener FDG und FMISO-Konturen zu einer gemeinsamen Kontur zusammengefasst (FDG, FMISO1, FMISO3). Nur in 2 Fällen trat das Rezidiv in der so eingegrenzten Region auf.
Schlussfolgerung.
Die FMISO-Verteilung variiert während der ersten beiden Therapiewochen erheblich, es erfolgt jedoch keine komplette Verschiebung des hypoxischen Subvolumens sondern eine unterschiedlich ausgeprägte Volumenveränderung. Die Überlappung der FMISO-PET-basierten Subvolumina mit dem Lokalrezidiv stärken die Hypothese, dass radioresistente Zellen in diesen Regionen das Rezidiv verursachen können. Die Variabilität des SUV_max und die geringe Rate an Rezidiven innerhalb einer reproduzierbar abgrenzbaren FDG und FMISO aviden Region sprechen jedoch gegen eine, rein voxelbasierte, Dosisverschreibung.

A spin-1/2 Heisenberg antiferromagnet (AF) on a triangular lattice is the paradigmatic model in quantum magnetism, which was intensively studied. In spite of numerous theoretical studies (which predict a rich variety of grounds states, ranging from a gapless spin liquid to Néel order), many important details of the phase diagram of triangular-lattice AFs remain controversial or even missing. In order to test the theory experimentally, a precise information on the spin-Hamiltonian parameters for the materials of interest is highly demanded. Here, we present results of high-field electron spin resonance (ESR) studies of spin-1/2 Heisenberg AFs Cs₂CuCl₄ and Cs₂CuBr₄ with distorted triangular-lattice structures in magnetic fields up to 50 T [1]. In the magnetically saturated phase (H>H_sat), 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 first proven by applying it to Cs₂CuCl₄, revealing good agreement with inelastic neutron-scattering 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 coupling parameters in this frustrated spin system. The approach has a broader impact and can be potentially used for any quantum magnet with reduced (e.g., by the staggered Dzyaloshinskii-Moriya interaction) translational symmetry, resulting, as predicted, in emergence of a new exchange mode above Hsat

Crystalline ceramic materials show promise as potential waste forms for immobilization of high-level radioactive wastes. Rare earth (RE) phosphate ceramics have been found to be extremely stable over geological time scales and they show good tolerance to high radiation doses. These ceramics are able to incorporate radionuclides in well-defined atomic positions within the crystal lattice up to high (~25%) loadings, which will reduce the volume of waste in the radionuclide conditioning process. The dehydrated RE phosphates are known to crystallize in two distinct structures, depending on the ionic radius of the cation: the larger lanthanides from La3+ to Gd3+ crystallize in the nine-fold coordinated monazite structure, while the smaller lanthanides such as Lu3+ form eight-fold coordinated xenotime structures.
Structural information on the radionuclide substitution in these RE phophates can be obtained by site-selective time-resolved laser fluorescence spectroscopy (TRLFS). In our previous work we studied the structural incorporation of Eu(III), taken as an analogue for the long-lived trivalent actinides Pu(III), Am(III) and Cm(III) found in spent nuclear fuel, in the monazite LaPO4. Eu3+ was found to incorporate on the La3+ site in LaPO4 as expected, despite slight discrepancies between the ionic radii of the host and dopant cations.
In the present work we study synthetic Eu(III) doped LaPO4, GdPO4, and LuPO4, as well as mixtures thereof, to investigate the influence of the ionic radius and crystalline structure on Eu(III) substitution in the ceramic material. Results on Eu(III) substitution in the monazite and xenotime materials will be presented and influences of the ionic radii on Eu(III) substitution within the host cation sites will be discussed.

Im Rahmen dieser Dissertation werden eine Serie von Grundlagenexperimenten zur Ablagerung (Deposition) und Remobilisierung (Resuspension) von Aerosolpartikeln in turbulenten Strömungen beschrieben. Die Kernmotivation stellt die Quelltermanalyse von Druckentlastungsstörfällen von Hochtemperaturreaktoren (HTR) dar. Im Primärkreislauf früherer HTR-Forschungsanlagen wurden größere Mengen an radiologisch belastetem Graphitstaub gefunden. Dieser Staub scheint größtenteils durch Abrieb zwischen den graphitischen Kernstrukturen entstanden zu sein und verteilte sich während des fortlaufenden Reaktorbetriebs über sämtliche Oberflächen des Primärkreislaufs. Während eines Druckentlastungsstörfalls kann dieser Staub durch die Gasströmung remobilisiert und aus dem Primärkreislauf ausgetragen werden. Eine Quelltermanalyse solch eines Störfallszenarios erfordert die Kenntnis über die Menge und die räumliche Verteilung des Staubs, die radiologische Belastung sowie das Remobilisierungsverhalten in Bezug auf die zu erwartenden Strömungstransienten. Nach dem heutigen Stand von Wissenschaft und Technik kann die räumlich-zeitliche Verteilung des Staubs im Primärkreislauf für stationären Reaktorbetrieb unter Verwendung eindimensionaler Systemcodes abgeschätzt werden. Jedoch ist unbekannt, welcher Anteil des Staubinventars durch die Gasströmung remobilisiert und aus dem Primärkreislauf ausgetragen werden würde.
Zur systematischen Untersuchung des Staubtransportverhaltens in turbulenten Strömungen wurden zwei kleinskalige Versuchsanlagen entwickelt und eine Serie von Depositions- und Resuspensionsexperimenten durchgeführt. Die partikelbeladene Strömung in der Heißgasumgebung des HTR-Primärkreislaufs wurde über die Verwendung von Ähnlichkeitskennzahlen auf eine Luftströmung bei Umgebungsbedingungen herunterskaliert. Die Strömung und die Partikel wurden mittels hochauflösender, bildgebender und nichtinvasiver Messverfahren räumlich und zeitlich vermessen, um eine umfangreiche Datenbasis für die Analyse der Partikeltransportprozesse zu erstellen. Inhaltlich lassen sich die durchgeführten Untersuchungen in drei Teile gliedern. Der erste Teil besteht aus zwei Studien über die Deposition und Resuspension monodisperser, sphärischer Einzelpartikel in einer ungestörten, horizontalen Kanalströmung. Die systematische Variation experimenteller Randbedingungen wie der Partikelgröße, der Oberflächenrauheit und der Strömungsgeschwindigkeit ermöglichte die Quantifizierung der einzelnen Einflussgrößen. Im zweiten und dritten Teil der Dissertation wurden die Deposition und Resuspension einer mehrschichtigen Ablagerung (Partikel-Multilayer) zwischen periodischen Stufen und in einer Kugelschüttung untersucht, um die komplexe Interaktion zwischen der turbulenten Strömung und der Multilayer-Ablagerung weiter zu erforschen.
Die gewonnenen Erkenntnisse leisten einen Beitrag für die Quelltermanalyse des Staubtransports im HTR-Primärkreislauf und können für die Weiterentwicklung numerischer Strömungssimulationen des Partikeltransports in turbulenten Strömungen verwendet werden.

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The fracture behaviour of a component or specimen that contains a sharp notch is governed essentially by the same theoretical relations known from cracks. The blunt notch root only causes an increase of the resistance against crack initiation, which depends on the fracture mechanism. In the present paper, the relation between fracture toughness and notch toughness is investigated by simple analytical models. The derived formulas were compared with experimental results obtained from fracture toughness tests on RPV-steel 24 NiCrMo 3-7 at various temperatures. 1T-CT- and 0.4T-SEB-specimens that contained a sharp notch with a root radius of 0.06 mm introduced by spark erosion (EDM) instead of the standard fatigue crack were used. The predictions were found to agree well with the experimental data. The effect of the notch radius on fracture toughness is most pronounced in the brittle to ductile transition regime, where fracture toughness can be characterized by the master curve and the corresponding reference temperature T0 according to ASTM E1921. Accordingly, the effect of the notch radius can be quantified by a shift of T0. Since the shape of the transition curve depends on the notch radius, the procedure of ASTM E1921 to determine T0 is not applicable. An alternative is suggested. As limiting cases, ductile tearing and brittle fracture are also considered.

We have proven that the growth of Co68Fe24Zr 8 layers under external field yields a uniaxial anisotropy, defined by the direction of the field. No magnetic coupling is present between Co 68Fe24Zr8 layers when separated by a 3nm of Al70Zr30. The anisotropy axis can therefore be manipulated at will and the direction can be tailored, layer by layer in multilayers, by the choice of the direction of the applied field during growth. The g-factor (2.13) and the anisotropy constant, obtained from ferromagnetic resonance, support the existence of short-range order. The relation between the temperature dependences of magnetic anisotropy and magnetization are partially captured by Callen-Callen power law.

The non-equidistant Landau-level (LL) spectrum of graphene enables the investigation of the carrier dynamics of distinct LL transitions. We present pump-probe measurements on multilayer epitaxial graphene, complemented by microscopic modelling. The free-electron laser (FEL) FELBE served as radiation source at a wavelength of 16.5 µm, which corresponds to a photon energy of 75 meV. At a magnetic field of 4.2 T, the photon energy gets resonant with the energetically degenerate LL transitions LL-1 → LL0 and LL0 → LL1. Circularly polarized radiation allows one to address one of these transitions selectively.
Besides a strong increase of the pump-probe signal at 4.2 T, we observe a complex set of pump-probe signals for all four combinations of pump and probe polarization. For contrarily polarized pump and probe radiation, one would expect negative pump-probe signals, as the initial state of the probed transition is populated (pump: σ+; probe: σ-) or the final state of the probe gets depopulated.
Our measurements show the counterintuitive result of positive pump-probe signals for the case of σ+-polarized pump radiation. The experimental findings are well described by microscopic calculations based on the density matrix formalism, which helped to reveal the origin of this behavior.

Mit Hilfe der Kurzzeitspektroskopie ist es möglich die Ladungsträgerdynamik in unterschiedlichen Materialsystemen direkt zu untersuchen. Bei sog. „Pump-Probe-Messungen“ werden z. B. Ladungsträger oder Moleküle mit einem sehr intensiven, aber auch sehr kurzen Laserpuls angeregt. Ein zweiter, wesentlich schwächerer Puls wird verwendet um die verursachte Änderung zu messen. Durch eine zeitliche Verschiebung des zweiten Pulses kann gemessen werden, wie lange das System braucht um die Energie wieder abzugeben. Eine einfache Skizze eines Aufbaus für Pump-Probe-Messungen, sowie ein Beispiel für das Ergebnis einer Messung sind in Abb. 1 gezeigt. Diese Untersuchungen sind beispielsweise besonders wichtig zur Entwicklung und Optimierung elektro-optischer Bauelemente wie z. B. Detektoren oder optische Modulatoren.
Die erreichbare zeitliche Auflösung bei diesen Messungen hängt im Wesentlichen von der Pulsdauer des Lasersystems ab. In diesem Vortrag werden verschieden Lasersysteme zur Erzeugung ultra-kurzer Laserpulse in einem breiten Spektralbereich vom nahen bis zum fernen Infrarot vorgestellt (800 nm – 250 µm). Zu jedem vorgestellten System wird als Beispiel eine Messung der Ladungsträgerdynamik in Graphen gezeigt, das aus einem zweidimensionalen Gitter aus Kohlenstoffatomen besteht. Dieses relativ neue Material, für dessen Untersuchung der Nobelpreis für Physik 2010 verliehen wurde, ist neben der Verwendung in der Elektronik speziell für Anwendungen in der Optoelektronik interessant. Durch die Verwendung verschiedener Wellenlängen können in diesem Material unterschiedliche physikalische Effekte untersucht werden.

Purpose: In line with the long-term aim of establishing the laser based particle acceleration for future medical application the radiobiological consequences of electron delivery with the typical ultra-short pulses of ultra-high pulse dose rate have to be investigated.
Materials and methods: The radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance) was used to mimic the quasi-continuous electron beam of a clinical linear accelerator (LINAC) and to deliver electron pulses at the ultra-high pulse dose rate of 10^10 Gy min-1 either at the low frequency of a laser accelerator or at 13 MHz avoiding effects of prolonged dose delivery. The impact of pulse structure was analysed by clonogenic survival assay and by the number of residual DNA double-strand breaks remaining 24 h after irradiation of two human squamous cell carcinoma lines of differing radiosensitivity.
Results: The radiation response of both cell lines was found to be independent from electron pulse structure for the two endpoints under investigation.
Conclusions: The results reveal, that ultra-high pulse dose rate of 10^10 Gy min-1 and the low repetition rate of laser accelerated electrons have no additional influence on the radiobiological effectiveness of megavoltage electrons.

We present a microscopic explanation of the controversially discussed transient negative differential transmission observed in degenerate optical pump-probe measurements in graphene. Our approach is based on the density matrix formalism allowing a time- and momentum-resolved study of carrier-light, carrier-carrier, and carrier-phonon interaction on microscopic footing. We show that phonon-assisted optical intraband transitions give rise to transient absorption in the optically excited hot carrier system counteracting pure absorption bleaching of interband transitions. While interband transition bleaching is relevant in the first hundreds of fs after the excitation, intraband absorption sets in at later times. In particular, in the low excitation regime, these intraband absorption processes prevail over the absorption bleaching resulting in a zero crossing of the differential transmission. Our findings are in good qualitative agreement with recent experimental pump-probe studies.

A Co zigzag nanocolumn sample was grown by glancing angle deposition using molecular beam epitaxy. A structural study was carried out using scanning electron microscopy and the magnetic properties and the magnetoresistance were investigated at room temperature. Each zigzag consisted of six arms tilted with respect to each other by approx. 60°, had a club-like shape, diameter in the range of 20-100 nm, a single arm length of about 150 nm and a total height of approx. 370 nm. The magnetization hard axis was observed for the magnetic field oriented parallel to the zigzag long axis and the easy axis for the field oriented perpendicular to the long axis. The system exhibited very high maximum coercivity values, which could find potential applications. The angular dependences of the coercive field and the remanent to saturation magnetization ratio, as well as magnetoresistance curves, indicated the presence of curling magnetization reversal mode.

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As one of the most promising candidates for a diluted magnetic oxide material for spintronic and magneto optic applications, transition metal (TM) doped titanium dioxide (TiO2) has been extensively studied for last two decades. Up to date room temperature ferromagnetism (RTFM) has been reported for different types of TM dopants and also different types of preparation methods, such as ion implantation [1] or magnetron sputtering [2]. There is an ongoing debate on the origin of the ferromagnetic properties of TiO2, whether RTFM arises from unwanted clustering of the TM atoms, magnetic contamination from sample handling or the desired substitution of Ti by the TM dopants.
We have investigated Mn implanted TiO2 films with respect to the effect of the crystalline structure of the pristine film on the magnetic properties of the doped films. The films were prepared by DC magnetron sputtering using a high purity oxygen deficient ceramic TiO2-x target in Ar/O2 atmosphere. SrTiO3 (100) single crystals were used as substrates. In order to achieve different structures of TiO2, namely amorphous, polycrystalline anatase and epitaxial anatase, different substrate temperatures and post-growth annealing were applied. The as-prepared TiO2 samples have been implanted with Mn ions of 30 keV to 190 keV kinetic energy and variable fluence resulting in a homogenous Mn concentration of 5 at.% within a 150 nm thin layer below the film surface.
The structural changes upon implantation were followed by means of X-ray diffraction (XRD) measurements. Comparison of the diffraction patterns indicates ion-induced damage in the epitaxial film and the formation of Mn containing secondary phases in the polycrystalline material. Depth resolved defect concentration profiles of as-grown and Mn implanted films were determined by means positron annihilation spectroscopy (PAS) measurements based on Doppler broadening spectroscopy. Magnetometry measurements of Mn implanted films reveal ferromagnetism for amorphous and polycrystalline films whereas paramagnetism is observed for epitaxial films. The local environments of implanted Mn ions in different TiO2 structures were probed by X-ray absorption spectroscopy (XAS) in fluorescence mode.
In summary, we have found a significant influence of the as-grown film structure on the magnetic properties of Mn:TiO2. During the presentation the PAS and XAS data will be discussed with respect to the presence of defects and secondary phases in the Mn doped TiO2 films.

We demonstrate how planar microresonators (PMRs) can be utilized to investigate the angular dependent magnetic resonance response of single magnetic nanostructures. In contrast to alternative detection schemes like electrical or optical detection, the PMR approach provides a classical means of investigating the high frequency dynamics of single magnetic entities, enabling the use of well-established analysis methods of ferromagnetic resonance (FMR) spectroscopy. To demonstrate the performance of the PMR-based FMR setup for angular dependent measurements, we investigate the microwave excited magnons in a single Co stripe of 5x1x0.02 µm^3 and compare the results to micromagnetic simulations. The evolution of excited magnons under rotation of one individual stripe with respect to a static magnetic field is investigated. Besides quasi uniform excitations, we observe magneto-static as well as localized excitations. We find a strong influence of inhomogeneous dynamic and static demagnetizing fields for all modes.

Composite detectors made of stainless-steel converters and multigap resistive plate chambers have been irradiated with quasi-monoenergetic neutrons with a peak energy of 175 MeV. The neutron detection efficiency has been determined using two different methods. The data are in agreement with the output of Monte Carlo simulations. The simulations are then extended to study the response of a hypothetical array made of these detectors to energetic neutrons from a radioactive ion beam experiment.

Nanofiltration offers new perspectives for the treatment of mine drainage from former uranium mines, e.g. in East Germany. In this study the perfor-mance of various commercial nanofiltration membranes for a real mine water sample was determined experimentally and modelled. Experimental data is key to membrane selection and is necessary to validate modelling results. Mathematical modelling offers deeper insights into the interaction of uranium species with solid surfaces which also has the potential to extrapolate to other research fields.

An extensive literature review on existing models for interfacial heat transfer in flashing of pure liquids was carried out. It reveals that recent numerical simulations rely still on empirical closures. A correlation in terms of the Jakob number, Reynolds number and Prandtl number might be the most promising one. However, all the validation against experiment is limited to single spherical droplet or bubble. For large deformed bubbles and high void fractions, there are still no direct validation due to the lack of experimental data and complicated intervening physics. Improvement regarding the effect of bubble interaction, interfacial morphology and turbulence is necessary.

Flash boiling of water inside a converging-diverging nozzle and a vertical pipe under pressure release transients is investigated. Some representative assumptions and simplifications encountered in the literature are assessed. It is shown that a fully non-equilibrium model with two velocity fields and two temperature fields should be applied. Non-drag forces are necessary to predict the lateral distribution of bubbles, which is usually non-uniform. For large bubbles (dg>1mm), bubble translation has a significant contribution to the interphase heat transfer, and thus heat conduction would give a significant under-prediction. The most important point in the assessment of these interphase exchange closures is to have a reliable prediction of bubble size. On this topic there is still much to do, since a realistic modelling of bubble number density transport is still missing. Great efforts need to be invested in the development of generally applicable closure models for nucleation, bubble growth, coalescence and breakup, etc.

Pressurized Thermal Shock (PTS) has been identified as one of the most important industrial needs related to nuclear reactor safety. The PTS analysis is required to assure the integrity of the Reactor Pressure Vessel (RPV) throughout the reactor life. One important part of the PTS analysis is the thermal hydraulic analysis which must predict the local temperature fields experienced by the structural parts of the cold leg and especially of the RPV wall close to the cold leg nozzle. Such results are applied as the input data for further structural analyses. Several scenarios that describe what could occur in Small Break Loss Of Coolant Accidents (SB-LOCA) result in an Emergency Core Cooling (ECC) water injection into the cold leg of a Pressurized Water Reactor (PWR). The cold water mixes there with the hot coolant, which is present in the primary circuit. The mixture flows to the downcomer where further mixing of the fluids takes place. Single-phase as well as two-phase PTS situations have to be considered. In case of two-phase PTS situations the water level in the RPV has dropped down to or below the height of the cold leg nozzle, which leads to a partially filled or totally uncovered cold leg. Pressurized Thermal Shock implies the occurrence of thermal loads on the Reactor Pressure Vessel wall. In order to predict thermal gradients in the structural components of the Reactor Pressure Vessel (RPV) wall, knowledge of transient temperature distribution in the downcomer is needed. The prediction of the temperature distribution requires reliable Computational Fluid Dynamic simulations. The CFD models should be able to model the complex mixing processes taking place in the cold leg and the downcomer of the reactor pressure vessel (IAEA, 2001; Lucas et al., 2008, 2009).

In the framework of the NURESAFE project attempts have been made to continue improvement and validation of CFD modeling for two-phase PTS situations. The NEPTUNE_CFD, ANSYS CFX and TransAT codes are used in the project for PTS investigations. A CFD benchmark test on a reference TOPFLOW-PTS steam-water experiment is a part of these activities within the project.

The tunable bandgap and the high carrier mobility of Ge(1-x)Sn(x) alloys stimulate a large effort for bandgap and strain engineering for Ge based materials using silicon compatible technology. In this letter we present the fabrication of highly mismatched Ge(1-x)Sn(x) alloys by ion implantation and pulsed laser melting with Sn concentration ranging from 0.5 at. % up to 1.5 at. %. According to the structural investigations, the formed Ge(1-x)Sn(x) alloys are monocrystalline with high Sn-incorporation rate. The shrinkage of the bandgap of Ge(1-x)Sn(x) alloys with increasing Sn content is proven by the red-shift of the E1 and E1+Δ1 critical points in spectroscopic ellipsometry. Our investigation provides a chip technology compatible route to prepare high quality monocrystalline Ge(1-x)Sn(x) alloys.

The reactor pressure vessel (RPV) represents one of the most important safety components in a nuclear power plant. Therefore, surveillance specimen (SS) programs for the RPV material exist to deliver a reliable assessment of RPV residual lifetime. This report will present neutron fluence calculations for SS. These calculations were carried out by the codes TRAMO and DORT [1, 2]. This study was accompanied by ex-vessel neutron dosimetry experiments at Kola NPP. The main neutron activation monitoring reactions were Fe-54(n,p)Mn-54 and Ni-58(n,p)Co-85. Good agreement was found between the deterministic and stochastic calculation results and between the calculations and the ex-vessel measurements. The different influences on the monitors were studied. In order to exclude the possible healing effects of the samples due to excessive temperatures, the heat release in the surveillance specimens was determined based on the calculated gamma fluences. Under comparatively realistic conditions, the heating was up to 6 K.

Succinic dihydrazide (SDH), N-methyl-S-methyl dithiocarbazate (HDTCZ) and PEGylated N-methyl-S-methyl dithiocarbazate (HO₂C-PEG₆₀₀-DTCZ) are nitrido nitrogen atom donors employed for the preparation of nitride [M(N)]‐complexes (M = ^99mTc and ¹⁸⁸Re).
This study aims to compare the capability and the efficiency of these three N³⁻ group donors, in the preparation of [M(N)PNP]-based target-specific compounds (M = ^99mTc, ¹⁸⁸Re; PNP = aminodiphosphine). For this purpose, three different kit formulations (SDH kit; HO₂C-PEG₆₀₀-DTCZ kit; HDTCZ kit) were assembled and used in the preparation of [M(N)(cys~)(PNP3)]^0/+ complexes (cys~ = cysteine derivate ligands).
For each formulation, the radiochemical yield (RCY) of the [M(N)(~cys)(PNP3)] compounds, was determined by HPLC. The deviation of the percentage of RCY, due to changes in concentration of the N³⁻ donors and of the
exchanging ligand, was determined.
For ^99mTc, data clearly show that HDTCZ is the most efficient donor of N³⁻; however, SDH is the most suitable nitrido nitrogen atom donor for the preparation of [^99mTc(N)(PNP)]-based target-specific agents with high specific activity. When HO₂C-PEG₆₀₀-DTCZ or HDTCZ are used in N³⁻ donation, high amounts of the exchanging ligand (10⁻⁴ M) were required for the formation of the final complex in acceptable yield.
The possibility to usemicrogram amounts of HDTCZ also in [¹⁸⁸Re(N)] preparation (0.050 mg) reduces its ability to compete in ligand exchange reactions, minimizing the quantity of chelators required to obtain the final complex in high yield. This finding can be exploit for increasing the radiolabeling efficiency in [¹⁸⁸Re(N)]-radiopharmaceutical preparations compared to the previously reported HDTCZ-based procedure, notwithstanding a purification process could be necessary to improve the specific activity of the complexes.