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Novel indole radiotracers for 123I and 99Tcm labeling were designed. The corresponding reference compounds (Indole-I and Indole-MAMA-Re) and the precursor for 99Tcm labelling were synthesized. The compounds were characterized by IR, NMR, and MS analyses. Competition binding assays in vitro show that the Ki values of Indole-I for σ1 and σ2 receptors are (0.574 ± 0.355) μmol/L and (0.162 ± 0.030 2) μmol/L, respectively. The Ki values of Indole-MAMA-Re for σ1 and σ2 receptors are (3.75 ± 2.22) μmol/L and (7.83 ± 4.87) μmol/L, respectively. Furthermore, 99Tcm-Indole-MAMA was successfully prepared. The radio-chemical purity (RCP) of 99Tcm-Indole-MAMA after purification was higher than 90% by HPLC analysis. The compounds reported in this paper may be used as lead compounds for further structural modification to develop indole SPECT tumor imaging agents.

The sorption of selenium(VI) onto pure anatase, a polymorph of titanium dioxide, was investigated. At the macroscopic level, batch experiments and electrophoretic mobility measurements have been performed. Selenium(VI) retention was found to be pH-dependent, i.e. sorption of selenium(VI) decreases with increasing pH (pH range 3.5-11). Selenium(VI) sorption dependence on the ionic strength was also evidenced, i.e. sorption increases while the ionic strength decreases. Electrophoretic mobility measurements showed that selenium(VI) sorption had no effect on the isoelectric point of anatase. At the microscopic level, XPS (X-ray Photoelectron Spectroscopy) measurements evidenced the absence of reduction of selenium(VI) during the sorption process. Furthermore, the nature of the sorbed surface species at the anatase/liquid interface has been elucidated using Attenuated Total Reflection Fourier-Transform Infrared (ATR FT-IR) spectroscopy. The spectroscopic results strongly suggest the formation of outer-sphere complexes on the whole pH range, which is in agreement with batch sorption experiments and electrophoretic mobility findings.

Aim: Alterations of α7-nAChR have been observed in schizophrenia, brain trauma and neurodegenerative diseases. For PET imaging of α7 nAChR [18F]NS10743 has been successfully developed and evaluated in mice by tissue distribution and specificity studies. Here we report on baseline and blocking PET studies with [18F]NS10743 in pig brain.

Materials and Methods: Dynamic PET scanning (2h) was performed in anesthetized female piglets (13-15 kg), intravenously injected with ~ 330 MBq [18F]NS10743 (specific activity >150 GBq/µmol). Three animals additionally received 5 mg/kg of the α7 nAChR antagonist NS6740. Plasma samples were taken and metabolite-corrected input functions were estimated. Individual regions of interest were defined using an MRI-based template of pig brain. SUV, distribution volume (VT= K1/k2) and binding potential (BPND = (VT region - VT reference)/VT reference) were estimated.

Results: [18F]NS10743 readily passed the blood-brain barrier and the uptake of radioactivity peaked with SUV = 2.23±0.71 at 8-10 min in the baseline scan while in NS6740-blocking studies the radioactivity levels peaked significantly earlier (SUV = 3.02 ± 1.28 at 6 min) and decreased faster. At the end of study (between 90 and 120 min pi) SUV was significantly decreased by NS6740 in all investigated brain regions except olfactory bulb, which was chosen as reference region for calculation of BPND. At baseline, a mean VT value of 6.07±1.54 was estimated with the highest radiotracer accumulation in temporal, parietal, and occipital lobe, thalamus, striatum, and middle cortex (VT = 7.27±1.95 – 7.10±1.58). Intermediate binding was observed in hippocampus, colliculi, midbrain, frontal lobe, and ventral cortex (VT = 6.76±1.71 – 6.09±1.05), and lowest values were assessed in the cerebellum, pons, and olfactory bulb (VT = 5.71±1.18 – 4.11±0.96). Baseline BPND values for high (temporal lobe), median (hippocampus) and low specific binding (cerebellum) were 0.76±0.07, 0.54±0.08, and 0.39±0.08, respectively. NS6740 significantly reduced the binding potential BPND in regions with high [18F]NS10743 binding (temporal lobe: -29 %, p = 0.01; midbrain: -35 %, p = 0.02) while the decrease in regions with low binding was not significant (cerebellum: -16 %, p = 0.2).

Conclusion: The data provide clear evidence of in vivo binding of [18F]NS10743 at α7 nAChR. However, with regard to the low density of α7 nAChR expression in the brain further modifications of the NS10743 core structure are needed to increase the target affinity of the tracer compound.

Background
Tumor-associated inflammatory cells (TAIC) are a major component of the tumor microenvironment and can contribute to both tumor progression and metastasis for instance by direct cell-cell interaction via membrane-bound proteins. Tumor cells show varying expression of Eph receptors and their ephrin ligands, which both are receptor tyrosine kinases. Eph/ephrins are hypothesized to be possible mediators of tumor-associated inflammation. The aim of our study was to analyze the distribution of ephrinB2 and its receptors EphB4 and EphB6 in inflammatory and melanoma cells and to clarify proinflammatory effects due to Eph/ephrin-mediated cell-cell contact.

Material and Methods
HL-60 promyelocytes and THP-1 monocytes, differentiated into granulocytes and macrophages, were used as a model for TAIC. Undifferentiated and differentiated cells were co-cultivated with Mel-Juso and A2058 melanoma cells. EphrinB2, EphB4 and EphB6 mRNA expression and protein synthesis was investigated using qRT-PCR and flow cytometry. Secretion of the proinflammatory cytokines IL-6 and TNF-α was analyzed using ELISA.

Results
No alteration in gene expression of ephrinB2, EphB4 and EphB6 could be observed during differentiation of HL-60 and THP-1 cells. In contrast, protein synthesis of ephrinB2, EphB4 and EphB6 was two- to threefold higher in HL-60 granulocytes compared to HL-60 promyelocytes and HL-60 macrophages. THP-1 macrophages showed a slightly increased protein synthesis of EphB4 and EphB6 compared to THP-1 monocytes whereas ephrinB2 protein content remained constant. Co-culture of both THP-1 monocytes and macrophages with Mel-Juso cells caused a substantial increment in secretion of proinflammatory cytokines. Co-culture of both HL-60 granulocytes and THP-1 monocytes with A2058 cells did not affect cytokine secretion. By contrast, co-culture of HL-60 macrophages with A2058 cells resulted in increased IL-6 secretion whereas co-culture of THP-1 macrophages with A2058 cells resulted in increased IL-6 secretion but decreased TNF-α release.

Conclusions
To our knowledge, mRNA expression and protein synthesis of ephrinB2, EphB4 and EphB6 was investigated for the first time in undifferentiated and differentiated HL-60 and THP-1 cells and, moreover, in Mel-Juso and A2058 melanoma cells. Co-culture of TAIC with melanoma cells resulted in proinflammatory effects. To differentiate the role of various Eph receptors and ephrin ligands in mediation of these effects after direct cell-cell contact of TAIC and melanoma cells selective inhibitors for Eph are applied in ongoing studies.

Introduction: The AMS business is booming: Many low-energy (< 1 MV) facilities, which are fully dedicated for ¹⁴C-analysis, are under construction or in funding status. Additionally, medium-energy accelerators such as the British 5 MV-NEC machine at “SUERC” Glas-gow, the French 5 MV-HVEE-machine “ASTER” at Aix-en-Provence [1] and the two German 6 MV-HVEE-machines “DREAMS” at Dresden [2] and “Cologne AMS” have been recently installed or are still in testing mode in Central Europe. Of course, these bigger machines need not only experienced physicists and technicians to get them running. It also seems to be advisable to have some experienced scientists around, who knows how to prepare AMS targets for ¹⁰Be, ²⁶Al, ³⁶Cl, ⁴¹Ca, and ¹²⁹I measurements.
Quality assurance: In contrast to the ¹⁴C-community, where e.g. round-robin exercises are routine business, the idea of quality assurance and traceable standards has only been brought up lately for the other cosmogenic radionuclides. Thus, world-wide accepted standards issued by metrology institutes are rare: NIST is selling two kinds of ¹²⁹I/¹²⁷I-standards, and the Institute for Reference Materials and Measurements (IRMM) provides one set of ⁴¹Ca/⁴⁰Ca solutions having eight different ratios [3]. Unfortunately, the most commonly used ¹⁰Be/⁹Be standard provided by NIST has been recently sold-out and will not be reissued. Other primary standard-type materials (²⁶Al,³⁶Cl), which are not commercially available, have been prepared by diluting certified activities and subsequent analysis within round-robin exercises [4,5]. After production of big quantities of in-house secondary standards for all nuclides, cross-calibration vs. primary standard-type materials has to be performed in-house and elsewhere [1].
Finally, as commercial ⁹Be contains intrinsic ¹⁰Be up to a level of 4x10^-14 [6] sophisticated production of in-house carriers, used as machine blanks and for processing samples, such as Be₂SiO₄ originating from a deep mine in Brazil (Fig. 1), is needed.

Fig. 1: Origins of terrestrial samples yet processed at FZD chemistry labs: Antarctica, Brazil (carrier), Italy, Macedonia, Nepal, Slovenia, Tajikistan and Turkey.

Only after production and measurement of all these materials, the AMS facility is ready for real sample measurements.
Real samples: As it is always not advisable to change two important “things” at the same time, here machine and chemistry, first and foremost, a close cooperation with the AMS teams of “ASTER” and “VERA” (Vienna Environmental Research Accelerator) needed to check the quality of the new chemical sample preparation at FZD.
A “good” AMS sample is defined by two main features: high stable isotope current and low isobar concentration. A high chemical yield and low concentrations of other elements – originating either from the matrix or chemical products used – are less important. A corresponding low processing blank, i.e. with a very low radionuclide/stable nuclide ratio, is, however, essential for projects working near the detection limit. For high sample throughput and reasonable costs a fast, easy and cheap chemical separation is also favorable. Though, as it is the case for most destructive analytical methods, AMS sample preparation takes much longer, i.e. 24 h (ice, water) to 2-4 weeks (sediments, rocks), and is more expensive than the actual AMS measurement [7], which takes about 10-60 min.
For ¹⁰Be-AMS-targets isolated from quartz-rich river sediments (Himalaya, erosion rate study) and a calcite-rich boulder from a Slovenian rockfall area, ⁹Be-currents had been in the range of “ASTER” standards and machine blanks. The processing blanks produced at FZD were in the same order as the machine blank (1x10^-15), thus, more than one order of magnitude lower than the lowest sample ratio.
Ten ³⁶Cl-AMS-targets prepared from river terraces (Anatolian Plateau, Turkey, uplift rate study) will be investigated in June at “VERA”, hopefully validating the high quality of ³⁶Cl-AMS targets.
Conclusion: We successfully started AMS chemistry in 2009 at FZD and are now open to more collaborations with research institutes and universities.
Acknowledgments: Thanks to E. Strub (²⁶Al-activity), M. Bichler (neutron-irradiation of ⁹Be), C. Varajão (Be₂SiO₄ crystals), AWI & U Heidelberg (Antarctic & Italian ice/snow samples), DAAD & DFG (cash) & L. Benedetti, R.C. Finkel, I. Mrak, W. Möller, HVEE, FZD-AMS-team (great cooperation).
References: [1] Arnold M. et al. NIMB 268 (2010) 1954. [2] Akhmadaliev Sh. et al. this meeting. [3] Hennessy C. et al. NIMB 229 (2005) 281. [4] Merchel S., Bremser W. NIMB 223–224 (2004) 393. [5] Merchel S. et al. GCA 73 (2009) A871. [6] Merchel S. et al. NIMB 266 (2008) 4921. [7] Merchel S., Herpers U. RCA 84 (1999) 215.

In various insulators, the impact of individual slow highly charged ions (eV-keV) creates surface nanostructures, whose size depends on the deposited potential energy. Here we report on the damage created on a cleaved BaF2 (111) surface by irradiation with 4.5×q keV highly charged xenon ions from a room-temperature electron-beam ion trap. Up to charge states q=36, no surface topographic changes on the BaF2 surface are observed by scanning force microscopy. The hidden stored damage, however, can be made visible using the technique of selective chemical etching. Each individual ion impact develops into a pyramidal etch pits, as can be concluded from a comparison of the areal density of observed etch pits with the applied ion fluence (typically 10⁸ ions/cm²). The dimensional analysis of the measured pits reveals the significance of the deposited potential energy in the creation of lattice distortions/defects in BaF2.

Ge (100) surfaces were irradiated by heavy Bi⁺ and Bi⁺⁺ ions extracted from a Bi-liquid metal ion source in a mass separated focused ion beam system with energy of 30 and 60 keV, respectively. Networks of different nanoporous (or sponge like) structures were found depending on ion energy, fluence, angle of incidence and irradiation temperature. The porous and amorphous surface structures are explained in terms of high concentration vacancies close to the surface. The surface modification was investigated using SEM and AFM imaging and FIB for cross section preparation.

The paper reports on new developments in the field of measuring techniques for liquid metal flows. We present three variants of a fully contactless electromagnetic flow meter for determining the integral flow rate in a channel flow. Respective test measurements have been performed at a liquid sodium and lead loop, respectively. One of the sensors is of particular interest since its operation does not depend on the electrical conductivity of the liquid metal, hence it is independent on the melt temperature. The Ultrasound Doppler Velocimetry (UDV) determines the velocity profile along the ultrasonic beam, and has the capability to work even through the channel wall. We present measurements obtained in a liquid sodium channel flow. Further, we report on the development of a contactless magnetic tomography of the global flow pattern in liquid metals. This method provides the full three-dimensional mean velocity distribution in a given liquid metal volume.

Trace elements are more significant for provenance of archaeological metallic artifacts than the main components. For gold, the most promising elements are Platinum Group Elements (PGE), Sb, Hg, Pb, and, especially for alluvial (panned) gold, Sn and Pt. Several small fragments of ancient gold objects from some Bronze Age objects and Greek and Dacian (KOSON – type) coins were analyzed. To check if the Transylvanian gold was used, some fragments of nuggets from Transylvanian mines and alluvial gold were also studied. The measurements were performed by using the AGLAE accelerator of the Centre de Recherche et de Restauration des Musees de France. The samples were bombarded with a 3 MeV proton micro-beam (roughly 50 µm diameter). The employed beam current was around 10 nA. We also used the micro-PIXE technique at the nuclear microprobe facility of the Forschungszentrum Dresden-Rossendorf. A 3 MeV proton beam was employed; the beam diameter was roughly 150 μm. The total accumulated charge was around 3 μC.
As conclusions of the performed experiments, one can quote the following findings:

• Sn was detected as a trace-element in all the KOSON without monogram coins; in one of them we could acquire spectra in several spots; in one of them a very high concentration of Sn was found but not in the surrounding areas, most probably a cassiterite grain;
• No trace-elements were detected in the KOSON with monogram coins and the pseudo-Lysimach staters issued by the Greek colonies at the Black Sea coast; it was concluded that highly refined gold was used to manufacture these coins; the above findings led us to the idea that the two kind of KOSON coins were manufactured by using different gold sources
• Sn was also found as trace element in a fragment taken from a Early Bronze Age bracelet from Tauteu, hoard (Transylvania) and in a fragment from the Vulchitrun-like disk (Late Bronze Age) found in Calarasi, Oltenia; we could conclude that alluvial gold was most likely used to manufacture these Bronze Age objects;
• Te was found in several geological samples (e.g. in the ones from Rosia Montana), a fact that is of particular importance, since this element appears to be a characteristic of the Transylvanian gold minerals, but it is easily evaporated during the native gold melting, so, its presence in gold objects is very improbable;
• A very interesting finding was the presence of Pd traces in one of the alluvial gold samples, the one coming from Mures river.

Recently, the role of microbial activity in mineral formation has become of great interest. In this case, the question arose for platinum–palladium nuggets recovered from an alluvial deposit (unconsolidated sediments deposited by streams) in the state of Minas Gerais in Brazil [1]. The morphological features of these aggregates of noble metals intuitively suggest that biological processes play a role in the formation of these particles. However, a geochemical fingerprint of microbial activity in precious-metal fixation is lacking. Iodine can provide such a fingerprint because it is a strongly biophile element. However, the detection of iodine at the µg/g level in a heavy matrix is quite challenging.
There are various techniques for the quantitative chemical analysis based on the detection of X-rays. Two of these techniques are PIXE (Particle Induced X-ray Emission) and XRF (X-Ray Fluorescence). In the past, only PIXE could be combined with a focussed ion beam to obtain elemental distribution maps with micrometer lateral resolution. PIXE was performed using a 3 MeV and 2 MeV H⁺ beam focussed to about 5x5 µm² coming from a 3 MV Tandetron accelerator at FZD, Dresden [2]. Another possibility is a mobile micro-XRF spectrometer, called MICROTAX or ArtTAX [2], in which X-rays from an X-ray tube are focussed by a polycapillary lens to a spot size of less than 100 µm. Both techniques, PIXE and µ-XRF, failed in detecting any iodine. The best detection limit obtained by PIXE was 70 µg/g for I in this matrix.
Nowadays, Synchrotron Radiation-induced XRF (SR-XRF) can also achieve spot sizes in the micrometer range. The SR-XRF analysis was carried out at the high energy beam line of the BAM, BAMline, at BESSY II. The excitation energy was 40 keV. An ~1 µm² spot size was achieved by focusing with an compound refractive lens CRL [3]. Only SR-XRF succeeded and indicated a significant positive correlation between iodine and palladium concentrations.
The measurements confirm that SR-XRF is very suitable for the detection of trace elements in heavy-metal matrices, which is mainly due to the tunability of the X-ray energy. The results of the SR-XRF measurements suggest that iodine may be used as a tracer for biologically mediated mineral formation.
[1] A.R. Cabral et al., Econ. Geol. 104, 1265-1276 (2009)
[2] F. Herrmann and D. Grambole, Nucl. Instr. Meth. B 104, 26-30 (1995)
[3] H. Bronk et al., Fresenius J Anal Chem 371, 307–316 (2001)
[4] E. Strub et al., Nucl. Instr. Meth. B 266, 2165-2168 (2008)

Ferritic/martensitic ODS-steel has been proposed as one of the best candidates as structural materials to be located in future fusion reactors, i.e. ITER and DEMO. One of the points of concern in further material development for fusion applications is the study of the diffusion and/or retention of light atoms, like H, which can be produced by transmutation. In this work, we investigated the chemical composition as well as the H distribution for H as-implanted and post-implanted annealed ODS-steel samples by means of simultaneous µ-PIXE and µ-ERD measurements. In general, µ-PIXE data evidence a quite inhomogeneous distribution of yttrium in some of the samples. It has been found that those regions with a larger Y content correspond with iron- and chromium- depleted regions. The possible correlation between Y and H content is discussed, on the basis of a large H diffusion even at room temperature.

Photoactivation measurements on Sm-144 have been performed with bremsstrahlung endpoint energies from 10.0 to 15.5 MeV at the bremsstrahlung facility of the superconducting electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf. The measured activation yield for the Sm-144(gamma,n) reaction is compared with the calculated yield using cross sections from previous photoneutron experiments. The activation yields measured for all disintegration channels Sm-144(gamma,n), (gamma,p), and (gamma,alpha) are compared to the yield calculated by using Hauser-Feshbach statistical models. A new parametrization of the photon strength function is presented and the yield simulated by using the modified photon strength parameters is compared to the experimental data.

Background:

Neurotensin (NT) and its receptors (NTR) are overexpressed in various tumors (breast, prostate, lung, ductal pancreas, pituitary) and play a crucial role in tumor progression and malignancy. For tumor diagnosis and optimized targeted, individualized therapy it is important to image and quantify functional expression of these receptors. The development and radiopharmacological characterization of a novel stable neurotensin analog radiolabeled with ⁶⁴Cu is described.

Material and methods:

The peptide (ArgΨ(CH₂NH)ArgProdmTyrtLeuLeu-OH) was synthesized by manual solid phase synthesis on a Merrifield-resin and conjugated with DOTA (1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid). Radiolabeling of the peptide (3 nmol) with ⁶⁴CuCl₂ was carried out in 0.1 M ammonium acetate at pH 5.5, 37°C and 15 min. The IC₅₀ was determined on HT-29 cell membranes. Cell uptake and internalization was studied in HT-29 and PC3 cells. The biodistribution of the radiotracer was investigated in HT-29 tumor bearing NMRI nu/nu mice (5 min, 60 min p.i.; 4 animals per time point) and imaged by small animal PET (8 animals). The metabolic stability was analyzed in Wistar rats.

Results:

The binding affinity of the radiotracer towards NTR1 was 7 nM (4-12 nM, 95% confidence interval). The radiochemical purity after one step radiolabeling was greater than 92%. After single intravenous administration the activity concentration increased fast in the tumor (0.8±0.1 SUV, 5 min p.i.) and decreased to 0.3±0.1 SUV (60 min). At 60 min p.i. the tumor to organ ratios were 2.8±0.7 (blood), 5.2±0.9 (muscle), 4.2±0.6 (pancreas), 0.6±0.5 (liver), and 0.4±0.4 (kidneys). The radiotracer was fast accumulated in the kidneys (3.7±0.6 SUV, 5 min p.i.; 0.8±0.1 SUV, 60 min p.i.) and eliminated in the urine (60±6% injected dose, 60 min p.i.). The tumors were clearly delineated in the PET images. The tumor uptake of the radiotracer was competitively inhibited by 73% by simultaneous injection of the neurotensin derivative 8-13. In rat plasma 33% of the radioactivity accounted for the original compound at 60 min p.i.

Conclusions:

The novel ⁶⁴Cu-neurotensin analog with good stability and high receptor affinity allows for the in vivo imaging and functional characterization of NTR1 receptor overexpressing tumors. These findings are a prerequisite for other imaging applications, e.g., using SPECT radionuclides (¹¹¹In), and potentially also for targeted radionuclide therapy (⁶⁷Cu, ⁹⁰Y or ¹⁷⁷Lu).
Acknowledgement: This project was supported in part by the EC (Grant agreement no. 223057, GIPIO).

Background
Cyclin-dependent kinases 4 and 6 (Cdk4/6) function as critical activators of cell cycle progression in human tumors. Pyrido[2,3 d]pyrimidine derivatives CKIA and CKIE are selective Cdk4/6 inhibitors with high potency for the inhibition of G1 phase progression and tumor cell proliferation. The aim of this study was the evaluation of radiolabeled compounds [¹²⁴I]CKIA and [¹⁸F]CKIE as radiotracers for PET imaging of Cdk4/6 in tumors in vivo.

Materials and methods
Cellular uptake of radiotracers [¹²⁴I]CKIA and [¹⁸F]CKIE was studied in human colorectal (HT-29) and squamous cell (FaDu) carcinoma cells. Small animal PET studies of both radiotracers were performed in FaDu xenograft-bearing nude mice.

Results
Radiotracer uptake studies showed fast and high uptake (up to 800%ID/mg protein) of [¹²⁴I]CKIA in both cell lines after 1 h at 37°C. Cellular uptake of [¹⁸F]CKIE was lower (HT 29, 46.3±11.2%ID/mg protein; FaDu, 46.2±13.8%ID/mg protein). Radiotracer uptake was significantly lower at 4°C for [¹²⁴I]CKIA (150%ID/mg protein) and [¹⁸F]CKIE (15%ID/mg protein) after 1 h in both cell lines. Cellular uptake of [¹⁸F]CKIE was reduced to 18.0±4.9%ID/mg protein in the presence of 10 µM of nonradioactive CKIE at 37°C. Dynamic small animal PET studies showed rapid clearance of [¹²⁴I]CKIA and [¹⁸F]CKIE from the blood and fast hepatobiliary excretion. The half-life of radiotracer elimination from the blood was calculated to be 7.2 min for [¹²⁴I]CKIA and 7.9 min for [¹⁸F]CKIE, respectively. Radiotracers were rapidly metabolized in blood in vivo, yielding >90% (1 min p.i.), 20% (30 min), and <5% (1 h) of the original compounds. Small animal PET studies with [¹²⁴I]CKIA only showed marginal uptake of the radiotracer in the FaDu tumor. In the case of [¹⁸F]CKIE a higher uptake was detected in the peripheral proliferative region of the tumor after 1 h p.i. However, the constant tumor-to-muscle ratio of 1.5 suggests a non-Cdk4/6-mediated uptake of [¹⁸F]CKIE in human tumor xenografts in mice.

Conclusions
Synthesis of pyrido[2,3-d]pyrimidine-based radiotracers [¹²⁴I]CKIA and [¹⁸F]CKIE allowed for the first time the quantification of cellular uptake in vitro and imaging of tissue-specific distribution of Cdk4/6 inhibitors in vivo. However, the short biological half-life in the blood and low tumor uptake of [¹²⁴I]CKIA and [¹⁸F]CKIE limit the use of both radiotracers for the characterization of Cdk4/6 expression in tumors by means of PET. Further development of suitable radiolabeled Cdk4/6 inhibitors for functional characterization of Cdk4/6 in tumors continues to be of great interest in current translational cancer research.

Background:

It is accepted that X-ray irradiation influences growth, viability and metastatic potential of tumor cells. Furthermore, it is supposed that tumor cell invasion and metastasis is regulated by Eph receptors and their ephrin ligands. The aim of our study was to investigate the influence of irradiation on cell viability, growth, and metastasis in human melanoma cells and whether this is mediated by dysregulated Eph receptor or ephrin ligand expression.

Material and Methods:

Primary (Mel-Juso) and metastatic (A375, A2058) human melanoma cell lines were irradiated with 5 or 10 Gy. Up to 7 days after irradiation we examined cell viability (MTT test). At 1 day and 7 days post irradiation we further analyzed cellular growth, motility (scratch assay), adhesion to fibronectin, and migration through a porous membrane. Furthermore, the mRNA expression of 8 different Eph receptors and 6 ephrin ligands was analyzed using RT-PCR.

Results:

In all cell lines a dose dependent decrease in viability and cell growth for up to 1 week after irradiation was demonstrated. Analysis of metastatic properties 1 day after X-ray showed decelerated scratch closure, slight increase in migration, and increased adhesion to fibronectin in all investigated cell lines. In contrast, 1 week after irradiation we detected faster scratch closure in irradiated primary Mel-Juso cells but unaltered motility in metastatic cell lines and, moreover, decreased migration in primary Mel-Juso cells and, by trend also in metastatic A375 cells. In addition, in Mel-Juso and A375 cells capability to adhere to fibronectin remained elevated. RT-PCR analysis revealed that Eph receptors and ephrins investigated have similar mRNA expression levels in primary and metastatic cell lines, with exception of both EphA2 and ephrinA5 showing enhanced expression in metastatic A375 cells. After irradiation changes in mRNA expression were not
detected with exception of an increase in EphA2 and EphA3 in A375 cells and ephrins A1 and A5 in A375 and Mel-Juso cells 7 days after treatment.

Conclusion:

Irradiation considerably influences viability and metastatic properties of melanoma cells. The different effects depending on time after irradiation observed suggest an involvement of cell-cell interaction via A-type Eph receptors and ephrins in irradiation-induced metastatic potency of melanoma cells.

Background:

Radiotherapy of various cancers is closely associated with increased cardiovascular morbidity and mortality. Arachidonic acid metabolites are supposed to play a key role in radiation-induced vascular dysfunction, inflammation, and injury. This study was designed to evaluate the effects of novel selective cyclooxygenase-2 (COX-2) inhibitors on radiation-induced formation of arachidonic acid metabolites via cyclooxygenase-2 and oxidant stress pathways in endothelial cells.

Materials and methods:

Acute effects (1 d, 3 d) of X-ray radiation at moderate doses (2 to 10 Gy) without or with presence of selective COX-2 inhibitors (cyclopentene/indole/indomethacin derivatives (2 each); 1 µM, 10 µM) in human arterial (HAEC) and microvascular (HDMEC) endothelial cells compared to sham-irradiated controls were assessed. Therefore, the following parameters were measured: COX-2 induction; secretion of cytokines tumor necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1; release of prostaglandins PGE2 and PGI2; release of isoprostanes 8-iso-PGE2 and 8-iso-PGF2α; and oxidative stress (lipid peroxides).

Results:

Irradiation of endothelial cells without presence of COX-2 inhibitors resulted in a dose-dependent augmentation of all parameters studied. When endothelial cells were exposed to COX-2 inhibitors during and for 24 h post irradiation, indole derivatives showed highest potency to inhibit release of both prostaglandins and isoprostanes. Furthermore, when irradiated cells were treated with indole derivatives a significant decrease of lipid peroxide formation and cytokine secretion could be observed, which indicates a direct interaction with oxidant stress-pathways. By contrast, both cyclopentene and indomethacin derivatives majorily inhibited prostaglandin release, but showed only slight effects on formation of isoprostanes, lipid peroxides and cytokines. Model experiments using human low density lipoproteins oxidized by radiolytically generated oxygen radicals showed that indole derivatives differently interact with peroxidation of polyunsaturated fatty acids, than the cyclopentene/indomethacin derivatives, suggesting a physico-chemical rationale for observed anti-oxidant activity.

Conclusion:

Indole-based selective COX-2 inhibitors substantially decreased radiation-induced formation of vasoactive isoprostanes
8-iso-PGE2 and 8-iso-PGF2α by endothelial cells. These findings may have particular importance in radiation-induced processes in which COX-2 is induced and oxidant stress occurs. The reduction of radiation-induced vascular dysfunction by antioxidative COX-2 inhibitors may widen the therapeutic window of cyclooxygenase-2 targeted treatment.

Background
The calcium-binding protein S100A4 is associated with metastasis of different cancer entities, including melanoma. The multiligand receptor for advanced glycation endproducts (RAGE) has been suggested to interact with extracellular S100A4 protein. We hypothesized that the interaction between RAGE and S100A4 plays an important role in activation of growth, adhesion, motility and migration in a human melanoma cell line with high metastatic potential.

Materials and methods
In order to investigate the cellular role of the RAGE-S100A4 interaction in vitro, we produced recombinant S100A4 and soluble RAGE (sRAGE). Furthermore, we established A375 melanoma cells stably transfected with S100A4 using vector pIRES2-AcGFP1 (A375-S100A4). The overexpression of S100A4 has been verified by western blot and flow cytometry. Assays for determination of migratory, invasive and adhesive behaviour of A375-S100A4 cells were performed. Furthermore, specific interaction of S100A4 with RAGE was characterized by surface plasmon resonance spectroscopy using immobilized sRAGE.

Results
The overexpression of S100A4 did not influence growth properties and adhesive behaviour of the A375-S100A4 cells; however, it affects their motility and migratory activity in comparison to mock-transfected cells. A375-S100A4 cells show an increased secretion of S100A4 into the extracellular space and, in consequence, an enhanced RAGE protein expression. Molecular interaction studies revealed high affinity (lower micromolar range) of S100A4 towards immobilized sRAGE, suggesting a biochemical rationale for the observed effects.

Conclusion
This investigation shows that overexpression of S100A4 influences the metastatic behavior of A375 melanoma cells. The enhanced secretion of S100A4 leads to an autocrine upregulation of RAGE expression and synthesis in A375-S100A4 cells. The findings support the supposed functional role of RAGE-S100A4 interaction in promoting a metastatic phenotype of human melanoma.

We present the transverse momentum spectra and rapidity distributions of \pi^{-} and K^0_S in Ar+KCl reactions at a beam kinetic energy of 1.756 A GeV measured with the spectrometer HADES. The reconstructed K^0_S sample is characterized by good event statistics for a wide range in momentum and rapidity. We compare the experimental \pi^{-} and K^0_S distributions to predictions by the IQMD model. The model calculations show that K^0_S at low tranverse momenta constitute a particularly well suited tool to investigate the kaon in-medium potential. Our K^0_S data suggest a strong repulsive in-medium K^0 potential of about 40 MeV strength.

Here we report on direct transport measurements on a G-quadruplex covalently wired between two gold electrodes realized by the mechanically controllable break junction technique. We found that the G-quadruplex shows a rather high conductance. Interestingly, when the distance of both electrodes was reversibly varied over a several nm-span this conductance behavior persists reproducibly. These hitherto unprecedented properties make G-quadruplexes interesting candidates for nanoelectronic applications where varied distances between electrodes need bridging without loss of conductance.

Background:

Malignant melanoma is one of the most invasive and metastatic tumors. A common therapeutic approach towards metastases will combine radiation with chemotherapy and/or surgery. The interaction between tumor and inflammatory cells, e.g., via S100A4 (metastasin) and the receptor for advanced glycation endproducts (RAGE), is hypothesized to play a key role in metastasis of melanoma. In this study the contribution of para- and autocrine S100A4-RAGE activation to growth, motility and migration of metastatic melanoma and inflammatory cells before and post irradiation was investigated.

Materials and methods:

Mouse melanoma cells (B16), macrophages (RAW; a model for tumor associated macrophages (TAM)) and B16/RAW cocultures (ratio 1 to 5) were exposed to single dose irradiation (5, 10, and 20 Gy, compared to sham-irradiated controls) for 0, 3 and 6 days. S100A4 and RAGE expression in these cells was quantified via real-time RT-PCR, Western-blot analysis and immunochemistry. Cell growth and cellular viability was detected by MTT assay. Migration assays of non- and irradiated cells were performed with and without chemoattractants (supernatants of irradiated cocultures after 6 days). Additionally, the actin cross-linker L-plastin was investigated as a migratory marker.

Results:

Post irradiation, S100A4 and RAGE mRNA expression was significantly increased in B16 and RAW cells but not in cocultivated cells. S100A4 protein expression was only detected in irradiated B16 cells whereas RAW cells always showed high levels in non- and irradiated cells. Interestingly, cocultures showed only minor S100A4 expression levels with a further reduction of S100A4 after irradiation. In contrast, RAGE protein showed only slight differences. A significant reduction of cell viability was observed after irradiation via MTT assay. On the other hand, migratory activity was significantly increased in B16 and cocultures after irradiation whereas RAW cells showed a significant decrease. Furthermore, chemoattractants significantly induced the migration in non-irradiated B16 cells.

Conclusion:

Irradiation of both melanoma cells and macrophages alters their migratory and invasive activity. Under conditions of cocultivation these effects were more pronounced. We suppose an involvement of para- and autocrine regulation of extracellular S100A4 and its receptor RAGE in melanoma cells and TAM, thereby changing functional properties of melanoma cells towards a promigratory phenotype.

Background:

Recent studies showed increased expression of neurotensin receptors (NTR), particularly, NTR1 and NTR3, in various tumors, thus NTR is assumed a potential target for tumor imaging and therapy. However, the knowledge about the quantitative expression of NTR on mRNA and protein level, e.g., under hypoxic conditions is limited. The aim of this study was to develop a quantitative method for determination of absolute NTR mRNA amount in tumor and non-tumor cells and tissues. For method evaluation the NTR mRNA amounts in human colorectal (HT-29) and prostate (PC3) carcinoma cell lines under normoxic and hypoxic conditions in vitro were compared.

Material and methods:

A novel real-time RT-PCR method using an external standard was established. The elongation factor 1 alpha (EF1α) gene served as housekeeping gene and glucose transporter protein type 1 gene (GLUT1) was used as indicator for cellular hypoxic regulation effects. The derived standard curves allow for calculation of the number of specific mRNA molecules normalized to 1000 molecules of EF1α. Acute and chronic experimental hypoxia was induced by cultivation of cells at an oxygen concentration of 0.6% for 4 to 72 hours.

Results:

Both HT-29 cells and PC3 cells show high mRNA expression of NTR1 in normoxia. In acute hypoxia (

Conclusion:

A novel standardizable and reproducible quantitative method for measurement of NTR mRNA in cancer cells was established. The use of NTR1 as a target for imaging or therapy strongly depends on tumor cell type and tumor hypoxia. Ongoing investigations will compare quantitative mRNA expression with data on functional expression of NTR, e.g., protein synthesis and radioligand interaction, in human samples and rodent tumor (xenograft) models.

Nominally undoped, hydrothermally grown ZnO single crystals have been investigated prior to and after doping in remote H plasma. Characterizations have been made by temperature-dependent Hall effect (TDH) and low temperature photoluminescence (PL) measurements. The H content before and after the doping has been de-termined using nuclear reaction analysis and is compared to the density of shallow donors derived from the TDH measurements.
The electrical properties of the as-grown ZnO sin-gle crystals are found to differ significantly. This is as-cribed to the density ratio of shallow donors and compen-sating acceptors. PL measurements showed that AlZn, GaZn, and interstitial zinc (Zni) are prominent shallow donors in the as-grown samples.
Remote H plasma treatment produced a metallic conducting near-surface layer thus masking the electrical properties of the bulk. The electrical properties of the in-vestigated samples are very similar after the treatment, independent of the as-grown state, because the density of shallow donors far exceeds that of compensating accep-tors in the affected near-surface region. The maximum of the broad near-band-edge emission is found to be located at 3.3595 eV due to the high doping density.

Die vorliegende Arbeit entstand im Rahmen einer Kooperation des Forschungszentrums Dresden-Rossendorf mit Qimonda Dresden GmbH & Co. OHG. Mithilfe der hochauflösenden Rutherford-Streuspektrometrie (HR-RBS) wurden das Diffusionsverhalten und Schichtwachstum von ZrO2 auf SiO2 und TiN im Anfangsstadium untersucht. Auf Grund der exzellenten Tiefenauflösung von 0,3 nm an der Oberfläche stand die Analyse von Konzentrationsprofilen in ultradünnen Schichten, respektive an deren Grenzflächen im Vordergrund.
Zur qualitativen Verbesserung der Messergebnisse wurde erstmals ein zweidimensionaler positionsempfindlicher Halbleiterdetektor in den Aufbau der HR-RBS implementiert und charakterisiert. Außerdem wurde ein Messverfahren in Betrieb genommen, das mögliche Schädigungen durch den Ioneneintrag in die Messprobe minimiert. Durch die Optimierung der experimentellen Bedingungen und die Entwicklung eines Programmpaketes zur Unterstützung des Analysten konnte ein effizienter Routine-Messablauf erstellt werden.
Im Moment einer binären Kollision zwischen einfallendem Ion und Targetelement kommt es bei kleinem Stoßparameter zu Veränderungen des Ladungszustands der gestreuten Ionen, insbesondere durch die abrupte Geschwindigkeitsänderung des Projektils und der Überlappung der Elektronenwolken. Bei der HR-RBS mit Energie separierendem Dipolmagneten muss zur Interpretation von Streuspektren die Ladungszustandsverteilung der gestreuten Projektile bekannt sein. Erstmalig konnte eine signifikante Abhängigkeit der Ladungszustandsverteilung gestreuter C-Ionen sowohl von der Schichtdicke als auch der Ordnungszahl des detektierten Targetelements, hier der vierten Nebengruppe, nachgewiesen werden.
Diese gewonnen Erkenntnisse ermöglichten systematische Untersuchungen zum ZrO2-Schichtwachstum im Anfangsstadium. Zur Herstellung der ZrO2-Schichten wurde die Atomlagenabscheidung (ALD) verwendet. Anhand der nachgewiesenen Agglomeration von ZrO2 auf nativen SiO2 wurde mithilfe der Rasterkraftmikroskopie (AFM) zur Bestimmung von Oberflächenrauigkeiten eine Methode konzipiert, welche die Auswirkung lokaler Schichtdickeninhomogenitäten auf die niederenergetische Flanke eines Streuspektrums berücksichtigt. Auf dieser Grundlage durchgeführte Simulationsrechnungen ergeben, dass keine Diffusion von Zr in die darunter liegende Schicht stattfand, jedoch eine ZrSiO4-Grenzflächenschicht existiert. Für das Wachstum von ZrO2 auf TiN wird aus den hoch aufgelösten Streuspektren ein völlig anderes Verhalten abgeleitet. Messungen zu Oberflächentopografien der TiN-Schicht liefern nicht zu vernachlässigende Werte für die Rauigkeit. Um den Einfluss der Oberflächenrauigkeit auf die Form des hoch aufgelösten Spektrums erfassen zu können, wurde eine Software entwickelt. Auf Basis von AFM-Messungen ermöglicht dieses Programm das Extrahieren einer Energieverteilung aus den Weglängen von ausschließlich an der Oberfläche gestreuten Ionen. Unter Berücksichtigung des Effekts der Oberflächenrauigkeit auf die HR-RBS Spektrenform konnte die Diffusion von Zr in das polykristalline TiN erstmals verifiziert werden. Die Beobachtungen weisen daraufhin, dass bereits nach dem ersten ALD-Zyklus ein geringer Anteil der deponierten Zr-Atome bis in eine Tiefe von etwa 3 nm in das TiN diffundiert. Die vorläufigen Ergebnisse legen Korngrenzendiffusion nahe.

Using QCD sum rules we investigate the in-medium behavior of pseudo-scalar and vector mesons. The rho meson is considered within a scenario of pure chiral restoration by dropping the chirally odd condensates. The interplay of mass shift and broadening of the spectral function is highlighted. We apply finite density QCD sum rules to mesons consisting of a heavy and a light quark (D, Ds and B) and investigate their sensitivity to the chiral condensate and consider the splitting of particle and antiparticle spectral functions with increasing density of the ambient nuclear matter. In order to gain a more direct dependence on the chiral condensate and other potential order parameters of chiral symmetry we present a series of Weinberg-Shuryak type sum rules for heavy-light systems at finite densities. Furthermore, the special role of the gluon condensates for systems consisting of two heavy quarks (e.g. J/Psi) and the QCD trace anomalie allows an extension of the method to large temperatures at non-zero baryon densities using the Rossendorf quasi-particle model.

Mit Hilfe von QCD-Summenregeln untersuchen wir die Sensitivität von pseudoskalaren Mesonen bestehend aus einem leichten und einem schweren Quark (D, D_s und B) auf das chirale Kondensat und betrachten mögliche Verschiebungen oder Aufspaltungen der Massen (d.h. Änderungen der Spektralfunktionen) von Teilchen und Antiteilchen unter Annahme einer linearen Dichteabhängigkeit der Kondensate.
Um Systeme mit direkterer Abhängigkeit vom chiralen Kondensat zu untersuchen, betrachten wir Weinberg-Kapusta-Shuryak Summenregeln bei endlichen Dichten im schwer-leicht Sektor.
Die besondere Rolle der Gluonenkondensate in Systemen aus zwei schweren Quarks (z. B. J/psi) und deren Beziehung zur QCD Spur Anomalie ermöglicht eine Erweiterung der Methode der QCD Summenregeln auf Temperaturen nahe T_c. Unter Verwendung des Rossendorfer Quasi-Teilchen-Modells bestimmen wir die Temperaturabhängigkeit des Digluonen-Kondensats bei endlichen Baryondichten nahe T_c und diskutieren deren Auswirkung auf das J/psi.

The analytical simulation of the counter-current flow limitation phenomenon in a PWR is an essential element to understand safety-related issues in nuclear power plants. It is expected that the introduction of computational fluid dynamics (CFD) tools will enhance the accuracy of the simulation predictions compared to the established one-dimensional thermal hydraulic analyses. Nevertheless, the use of CFD for this complicated task is still a challenge today. Due to the need to understand the CCFL phenomenon in a PWR for reasons of safety and characterisation of normal operation, it is necessary to validate computer codes and to verify computational results using experimental data. Therefore it is also interest to prove the understanding of the general fluid dynamic mechanism leading CCFL and to identify the critical parameters affecting this phenomenon.

In order to improve the transient analysis of counter-current two-phase flows, experimental and numerical studies were conducted at Forschungszentrum Dresden-Rossendorf (FZD). A 1/3rd scale model of the hot leg PWR of a German Konvoy Pressurized Water Reactor with rectangular cross section was used. The experimental results on this topic were reported in previous reports [Deendarlianto et al. (2008) & Vallée et al. (2009)]. Selected an air-water CCFL experiment at 0.15 MPa and room temperature at FZD (experimental running number 30-09) was numerically modelled with three-dimensional two-fluid models of computer code CFX 12.0 (ANSYS CFX). The aim of this CFD simulation is to validate the prediction model of the CCFL with the existing multiphase flow models built in the commercial code ANSYS CFX. CFD simulation was performed using the multi-fluid Euler-Euler modeling approach or free surface model available in CFX. The calculation was carried out in fully transient manner using a gas/liquid inhomogeneous multiphase flow model coupled with a shear stress transport (SST) turbulence model. In the present numerical study, the drag coefficient was approach by using the Algebraic Interfacial Area Density (AIAD) model. The results indicated that quantitative agreement between calculation and experimental data was obtained for the occurrence of flooding point. Next, it was found also that a comparison with the high-speed video observations shows a good qualitative agreement.

Basic Phenomenon
Boron 10 = strong thermal neutron absorber
Used as boric acid solved in the coolant of PWRs to compensate excess reactivity inadvertant or unavoidable decrease of boron concentration (boron dilution) might result in a reactivity transient
Power peak depends on coolant mixing in Cold leg, Downcomer Lower plenum Density differences can strongly influence the mixing

CFD codes for application in horizontal multiphase flows:

the investigation of the feasibility of numerical prediction of stratified two phase flow with existing multiphase flow models in ANSYS CFX to prove the understanding of the general fluid dynamic mechanism
to identify the critical parameters (like e.g. slug length, frequency and propagation velocity, pressure drop, CCFL) to improve the multiphase flow modeling (interfacial momentum transfer, turbulence at the free surface et.) experimental data required for the validation

CFD (Computational Fluid Dynamics) is the simulation of fluids engineering systems using modeling (mathematical physical problem formulation) and numerical methods (discretization methods, solvers, numerical parameters, and grid generations, etc.)
CFD made possible by the advent of digital computer and advancing with improvements of computer resources (500 Floating Point Operations per Second (flops), 1947 1 Petaflops, 2009)

Strong increase of usage of three-dimensional Computational Fluid Dynamics (CFD) in industrial applications because for instance
slugging,
pressurized thermal shocks,
coolant mixing,
thermal striping
cannot be predicted by traditional one-dimensional system codes with the required accuracy and spatial resolution.

We have analyzed the coupling of ultraintense lasers (at ∼2×1019   W/cm²) with solid foils of limited transverse extent (∼10  s of μm) by monitoring the electrons and ions emitted from the target. We observe that reducing the target surface area allows electrons at the target surface to be reflected from the target edges during or shortly after the laser pulse. This transverse refluxing can maintain a hotter, denser and more homogeneous electron sheath around the target for a longer time. Consequently, when transverse refluxing takes places within the acceleration time of associated ions, we observe increased maximum proton energies (up to threefold), increased laser-to-ion conversion efficiency (up to a factor 30), and reduced divergence which bodes well for a number of applications.

The qualification of Computational Fluid Dynamics (CFD) codes for two-phase flows is an important topic in the frame of German CFD initiative initiated by the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS). This concerted action especially aims on phenomena in the primary system of light water reactors. Forschungszentrum Dresden-Rossendorf e.V. (FZD) is involved in both – the generation of CFD-grade databases and CFD model development and validation. The data obtained in our TOPFLOW experiments clearly show a separation of small and large bubbles over the pipe radius due to the action of the lateral lift force. This has a considerable influence on the local interfacial area density. Also the other bubble forces as drag and turbulent dispersion force clearly depend on the bubble size. For this reason it is important to introduce bubble size dependent velocities fields in a proper modeling of poly-dispersed flows.

The qualification of Computational Fluid Dynamics (CFD) codes for two-phase flows is an important topic in the frame of German CFD initiative initiated by the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS). This concerted action especially aims on phenomena in the primary system of light water reactors. The Transient twO Phase FLOW (TOPFLOW) test facility is one of the reference experimental facilities within this CFD network. One type of experiments aims on generation of CFD-grade data (i.e. data with high resolution in space and time) for poly-dispersed bubbly flows. Such data were obtained at the TOPFLOW facility for upwards vertical pipe flow using the wire-mesh sensor technique. Different experimental series were done for adiabatic air-water and steam-water flows as well as for condensing and evaporating flows. Beside bubbly flows the database also comprises measurements for slug, churn-turbulent and wispy-annular flows. The aim of this presentation is to give an overview on the available database.

The influence of the lateral lift force on trajectories of single bubbles under idealized conditions was investigated in the past by means of Direct Numerical Simulations (DNS) and by well defined experiments. However, contradictory discussions can be found in literature on the meaning of this force for poly-dispersed flows, i.e. flow with medium or high gas volume fraction. Usually such flows are turbulent and bubble-bubble interaction, i.e. bubble coalescence and breakup play an important role. For this reason it is not self-evident, that the correlation for the lift force coefficient obtained by Tomiyama can be applied for such flows.
The separation of small and large bubbles in poly-dispersed flows was clearly shown in experiments on vertical pipe flow basing on wire-mesh sensor measurements which allow the measurement of bubble size distributions. The critical diameter at which the lift force changes its sign predicted by the Tomiyama correlations (5.8 mm for air-water flow at ambient conditions) seems to fit in general well with the transition between wall and core peaks in the radial gas volume fraction profiles decomposed according to the bubble size. This was also confirmed for steam-water flows at a pressure of 6.5 MPa for which the critical diameter is at about 3.5 mm according to the correlation.
However in case of void fraction larger than about 5 % the effect of the lift force is superposed by dynamic effects as bubble coalescence and breakup and radial migration of the bubbles. For this reason it is not possible to conclude on the critical diameter directly from the shape of the radial gas volume fraction profiles. Also, it was argued, that the wall peak of small bubbles can be caused by large bubbles moving fast upwards in the pipe centre and pushing the small bubbles towards the wall. For this reason in the presented work the distribution of bubbles in dependence on radial position and on bubble sizes is investigated in detail for developing flows. New, high-quality data on air-water as well as on steam-water flows in a DN200 pipe are used for these investigations. The validity of the Tomiyama correlation can be confirmed for a wide range of flow rates. Finally the consequences of the lateral lift force on the flow bubble columns, on the stability of homogeneous bubbly flows and on bubble plumes produced by bubble entrainment from impinging jets are discussed.

The microstructural changes induced by the incorporation of large quantities of nitrogen in austenitic stainless steel are analyzed. Phase and texture modification as well as grain rotation are investigated by X-ray and electron backscatter diffraction. A quantitative dependence of the rotation on the grain orientation is determined by means of depth profiling and diffraction techniques. Correlation between local nitrogen interstitial content, associated crystallographic rotation and degree of texturing is established.

A correlation between the grain orientation and the out-of-plane magnetic properties of nitrogen-enriched polycrystalline austenitic stainless steel surface is performed. Due to the competition between the magnetocrystalline anisotropy, the exchange and dipolar interactions, and the residual stresses induced by nitriding, the resulting effective magnetic easy-axis can lay along unusual directions. It is also demonstrated that, by choosing an appropriate stainless steel texturing, arrays of ferromagnetic structures with out-of-plane magnetization, embedded in a paramagnetic matrix, can be produced by local plasma nitriding through shadow masks.

Crystallographic structure and lattice rotation of the ‘expanded’ austenite produced by means of low temperature plasma nitriding is investigated. The microstructure of the nitrogen enriched layer has been investigated by means of X-ray diffraction (XRD) while the lattice rotations in the nitrided zone were assessed by electron backscattered diffraction (EBSD). The nitrogen depth profiles have been determined by means of glow discharge optical emission spectroscopy and nuclear reaction analysis. XRD shows the presence of the ‘expanded’ austenite or γN phase in all the nitrided samples characterized by average larger lattice spacing in relation to non-nitrided steel matrix. EBSD investigation demonstrates that in addition to the lattice expansion nitrogen incorporation into the stainless steel matrix induces significant lattice rotations. The amount and direction of these crystallographic plane rotations are function of the initial orientation. An unusual evolution of the 220 γN line as a function of the nitriding duration is observed together with an anomalously high intensity ratio of the 111 and 200 γN and matrix lines. The XRD results are interpreted on the basis of the lattice rotations of diffracting planes, nitrogen concentration gradient, nitrogen diffusion anisotropy and residual stress. It shows that these rotations are a pertaining feature for the understanding of the γN microstructure.

Periodic precipitation patterns in C:Ni nanocomposites grown by energetic ion co-deposition are investigated. Films were grown at room temperature by ionized physical vapor deposition using a pulsed filtered cathodic vacuum arc. We reveal the role of the film composition, ion energy and incidence angle on the film morphology using transmission electron microscopy and grazing incidence small angle x-ray scattering. Under these growth conditions, phase separation occurs in a thin surface layer which has a high atomic mobility due to energetic ion impacts. This layer is an advancing reaction front, which switches to an oscillatory mode, producing periodic precipitation patterns. Our results show that the ion induced atomic mobility is not random, as it would be in the case of thermal diffusion, but conserves to a large extent the initial direction of the incoming ions. This results in a tilted pattern under oblique ion incidence. A dependence of the nanopattern periodicity and tilt on the growth parameters is established and pattern morphology control via ion velocity is demonstrated.

The immediate and accurate monitoring of chemical and biological substances is essential in environmental analysis for minimizing the health risk for citizens and their exposure to pollutants. Recently, considerable attention has been focused on endocrine-disrupting compounds (EDCs), such as estrogens, which constitute a wide group of environmental pollutants, especially in drinking water.
A new concept for measuring the concentration of such organic compounds by using Si-based, integrated light sources for fluorescence analysis is presented. In that concept the analyte, estrogen in this example, is labelled with a fluorescence marker and is immobilized at the passivated surface of the light emitter by receptor molecules.
The ion beam technology is one of the most essential steps of the light emitter fabrication. The integrated light emitters are based on a metal-oxide-semiconductor (MOS) structure. This oxide layer is implanted with Ge or rare earth ions (Gd and Tb) followed by annealing and SiON deposition. Depending on the implanted element there is a broad palette of MOS devices emitting light from the UV up to the red spectral region. The combination between Si-based integrated light emitter and this kind of biosensing opens a way to extremely small device dimensions and is of great interest for point-of-care measurements.

The current system was investigated Fourier-Transform infrared spectroscopy (FTIR), x-ray-photoelectron spectroscopy, photoluminescence (PL) and electroluminescence (EL) measurements.

Endocrine-disrupting compounds (EDC´s) constitute a wide group of environmental pollutants that causes severe effects on the people and wild life. Actually, considerable interests have been focused on quantification methods for analytical tracing of chemical substances in drinking water, as in food industry, and medical diagnostic.
A sensor concept for estrogen detection in waterish solutions by Silicon based light emitters (MOSLED) was developed. This concept is based on direct fluorescence analysis and consists of a certain arrangement of the bio- components and their fabrication methods as well as the measurement protocol.
The functionalization of the SiO2 surface of the MOSLED was realized by means of the new developed SSC (Spraying Spin Coating) method. The chemical precursors of this method are organofunctional silane groups with three different functional groups, namely the amino-, carboxyl-, and thiolgroups. These results have been compared with those of the literature. The optimization of the SSC-method was analyzed by means of standard surface science techniques like FTIR-, Raman-, and XPS-spectroscopy. The surface roughness was applied by using AFM-spectroscopy, which showed a smooth surface by the samples treated with the SSC-method.
In order to immobilize the hER(alpha) receptor at the surface, the receptor was bound to the molecular shell of the QDot655 dye and finally adsorbed to the silanized SiO2 surfaces. The fraction of the immobilized hER(alpha) receptors was controlled via Photoluminescence-measurements.
The whole concept of the sensor was tested at two water samples containing estrogen in different concentrations.

Positron-Emission-Tomography (PET) enables direct and quantitative monitoring of the spatio-temporal distributions of dissolved inert and/or reactive PET-nuclides and PET-nuclide-labelled compounds during their passage through decimetre-scaled material samples. We apply PET exclusively to geological samples and reach the physical resolution limit of about 1 mm with our small-animal-PET scanner (ClearPET, Raytest). We suggest our GeoPET has unrivalled sensitivity and selectivity for tracer concentrations to some 107 tracer atoms/µl and thus is ideally suited for direct flow and transport process observations in soils. This lower limit of the tracer concentration in the order of about 1 kBq/µl outranges other process observation methods (e.g. NMR or resistivity tomography) by many orders of magnitude. Like in the common medical practice, a combination with µCT for structural imaging would be advantageous for improving the spatial significance.
In the past we demonstrated the feasibility of the method, applying in-house developed and medical PET-scanners. The installation of the PET scanner in our controlled area makes possible long-term experiments and the application of non-standard and long-living PET-nuclides (like 124I, decay time 4 days, and 58Co, decay time 71 days). The installation of a new cyclotron will also extend the availability of short-living PET-isotopes for fast process observations (e.g. 11C, decay time 20 min). Application of these nuclides extends the common radiopharmaceutical practice of labelling organic compounds with 18F (decay time 110 min).
The density of geomaterials may cause more than 50% of Compton-scattered events, which degrade the image quality. The quantification of the resulting artefacts is under way by Mont-Carlo model-based tools and will significantly empower the scatter-correction procedures.
Transport observation studies have been conducted on consolidated, partially fractured rocks and on soils, often showing more or less localized transport pathways. The effective volume and transport network, as well as the effective surface area for specific process conditions can be derived directly and quantitatively from the spatio-temporal tracer distribution in the sample, which can be visualized as 3D-movie, in contrast to indirect observations based on break-through curves at the endpoint of the sample. Comparisons with Lattice-Boltzmann simulations based on structural information obtained by µCT are indicating, that any actual transport field very much depends on elusive boundary conditions and therewith represents just one instance of a variety of possible spatio-temporal distributions with similar effective parameters.

The present review intends to help its reader find a suitable method for temperature measurement in Millisecond Spike Annealing (MSA). For this purpose it is going to highlight current and former industrial and research approaches for both RTP (Rapid Thermal Processing) and MSA to measure the true wafer temperature.
The theoretical background of each measurement technique is considered along with its capability to be applied in MSA tools as well as its suitability for Industry in terms of time and temperature resolution.

The ability to embed interactive three-dimensional (3D) models into electronic publications in portable document format (PDF) greatly enhances the accessibility of molecular structures. Here, we report advances in this procedure and discuss what is needed to develop this format into a truly useful tool for the structural biology community as well as for readers who are less well trained in molecular visualization.

This paper reports on the use of the RELAP5 code for the simulation of flashing-induced instabilities in natural circulation systems. The RELAP 5 code is intended to be used for the simulation of transient processes in the Russian RUTA reactor concept operating at atmospheric pressure with forced convection of coolant. However, during transient processes, natural circulation with flashing-induced instabilities might occur. The RELAP5 code is validated against measurement data from natural circulation experiments performed within the framework of a European project (NACUSP) on the CIRCUS facility. The facility, built at the Delft University of Technology in The Netherlands, is a water/steam 1:1 height-scaled loop of a typical natural-circulation-cooled BWR. It was shown that the RELAP5 code is able to model all relevant phenomena related to flashing induced instabilities. The magnitude and frequency of the oscillations were reproduced in a good agreement with the measurement data. The close correspondence to the experiments was reached by detailed modeling of all components of the CIRCUS facility including the heat exchanger, the buffer vessel and the steam dome at the top of the facility.

Based on previous results on laser cooling of relativistic c3+ ion beams at the ESR storage ring we present new laser systems and optical diagnostics for laser cooling of relativistic ion beams.
In combination with a new Schottky detection and new beam profile measurement system currently tested at the ESR the new optical diagnostics will help to give new insight into the dynamics of laser cooled ion beams with unprecedented resolution.
With a scanning and a pulsed laser system newly introduced to the experiment we will be able to cool relativistic ion beams without the need of electron precooling. This will be of great importance for the laser cooling experiments at higher energies available at future storage rings.

Implementation of a modular Particle-in-Cell Algorithm for GPGPU Clusters

Talk on ion acceleration experiments at the FZD laser Draco and the first dose controlled irradiation of cell samples.

Talk on the status and prospects of the facility.

Nuclear power plant operators must demonstrate that the structural integrity of a nuclear reactor pressure vessel (RPV) is assured during routine operations and under postulated accident conditions. The aging of the RPV steels is monitored via surveillance programs. Radiation loading, metallurgical and environmental histories, however, can differ between surveillance and RPV materials. Therefore, the investigation of RPV material from decommissioned NPPs offers the unique opportunity to evaluate the real toughness response. Such an opportunity is now available through the investigation of RPV material from the decommissioned Greifswald NPP (WWER-440/V-230).
The Greifswald RPVs of 4 units represent different material conditions as follows:
• Irradiated (Unit 4),
• irradiated and recovery annealed (Units 2 and 3), and
• irradiated, recovery annealed and re-irradiated (Unit1).
The recovery annealing of the RPV was performed at a temperature of 475° for about 152 hours and included a region covering ±0.70 m above and below the core beltline welding seam.
Material samples of a diameter of 119 mm called trepans were extracted from the RPV walls. The research program is focused on the characterisation of the RPV steels (base and weld metal) across the thickness of the RPV wall.
This paper presents test results measured on the trepans of the beltline welding seam and base metal of the above mentioned conditions. The key part of the testing is focussed on the determination of the reference temperature T0 following the ASTM standard E1921-09 to determine the facture toughness, and how it degrades under neutron irradiation and is recovered by thermal annealing. Other than that the mentioned test results include Charpy-V and tensile test results. Following results have been determined:
• The mitigation of the neutron embrittlement of the weld and base metal by recovery annealing could be confirmed.
• KJc values of the weld metals generally follow the course of the MC though with a large scatter.
• There is a large variation in the T0 values evaluated across the thickness of the multilayered welding seams.
• The T0 measured on TS oriented SE(B) specimens from different thickness locations of the welding seams strongly depends on the structure along the crack tip.
• It was demonstrated that T0 evaluated according to the SINTAP MC extension represents the brittle fraction of the data sets.
• A direct correlation between T0 and TT41J of the investigated weld metal is questionable due to the different thickness location of the crack tip and the notch root in pre-cracked SE(B) and the reconstituted Charpy-V specimens, respectively.
• A strong scatter of the fracture toughness KJc values of the recovery annealed base metal of Unit 1 is observed with clearly more than 2% of the values below the fracture toughness curve for 2% fracture probability. The application of the multimodal MC approach describes the temperature dependence of the KJc values in a satisfactory manner.

Plants are able to accumulate uranium (U) in roots and shoots /1/. Hence, we could detect an accumulation of this metal inside suspension cells of canola (Bassica napus) via fluorescence microscopy. Such uptake of highly toxic heavy metals requires skilled complex cellular defense mechanisms.
One example is the formation of metal complexes in the cytosol. A prominent candidate might be the tripeptide glutathione (GSH) bearing metal chelating functionalities like carboxylato- and thiol residues. Whereas at pH 5.7 the formed complex was stable over 6 hours, the initial complexes at pH > 6.0 degraded within 30 minutes. A reduction of U(VI) by GSH seems to be possible, because of strong spectral changes contributed by thiolate functionality. However, the spectra of the later formed chelates indicated an involvement of SH-groups in U complexation.
This is necessary for the formation of phytochelatins based on GSH. These metal binding peptides could be detected by HPLC in the cytosol 24 hours after U contact. U was bound to these peptides revealed by gelelectrophoresis of isolated cytoplasmic peptides and subsequent Laser-induced Fluorescence Spectroscopy. Despite these GSH consuming processes during U contact, the cytoplasmic GSH content decreased only slightly but not significantly compared to the control. Artificial depletion of GSH induced an up to twofold increased metabolic activity of cells challenging with U concentrations ≤ 10 µM whereas higher U contents dramatically reduced the metabolism. These data underlines the tight cellular regulation and the importance of GSH in maintaining defense reactions against U.

/1/ K. Viehweger, G. Geipel, Environmental and Experimental Botany 69 (2010) 39–46

Recently it could be reported, that uranium can occur in its tetravalent oxidation state on the Surface of roots of Arabidopsis halleri /1/. Nevertheless it is very unusual to find uranium in this oxidation state in soil compartments located close to the earth surface, where oxidizing conditions dominate. The oxidation state +6 should be the stable under these conditions.
Flavonoids are widely distributed in plants and have multifunctional properties. They are known for there antioxidant activity Within this class of compounds quercetin is very widespread. Considering that quercetin may be involved in the reduction process we carried out experiments to reduce uranium-(VI) by quercetin. The experiments were carried in under N2-atmosphere to avoid reoxidation of the formed uranium-(IV). Under these in vitro conditions quercetin was able to reduce up to 10% of the uranium. Uranium-(IV) was determined directly by Laser-Induced Photoacoustic Spectroscopy and UV-Vis spectroscopy.
However, this does not explain the existence of uranium-(VI) on the roots. The redox potential of quercetin was measured as function of pH. The shift of the redox potential supports the reduction of uranium with increasing pH /2/. Additionally quercetin can act as complex forming agent. We studied the complex formation of quercetin with uranium-(IV) and uranium-(VI). In both cases a 1:1 complex was found and the stability constants were determined to be log β11 = 20.36 /2/ and log β11 = 13.8 /3/, respectively. This shows a strong stabilization of the uranium-(IV) in its complex with quercetin.
/1/ K. Viehweger, G. Geipel, Environmental and Experimental Botany 69 (2010) 39–46
/2/ S. Drewitz, Diploma thesis, TU Dresden 2010
/3/ K. Viehweger, G. Geipel, In Wissenschaftlich-Technische Berichte FZD-511, Annual Report 2008, (2009) 41.

The morphology of surfaces strongly influences optical, electrical, and magnetic properties of thin films. By changing the morphology it is possible to tailor the material properties. Oblique low energy ion beam sputtering produces periodic ripple structures with periodicities in the nanometer range. During sputtering the region near to the surface gets amorphous and some metal is deposited on the surface, i.e. Cu from the sample holder. These ripple patterns can be used as templates. By using amorphous ripples only polycrystalline films can be grown. These films have an morphology induced dipolar anisotropy. In order to grow the films epitaxially the ripples have to be crystalline. Hence, this could induce an additional anisotropy in a magnetic overlayer. One possible route to achieve crystalline ripples is annealing. Therefore, the annealing temperature dependence was studied using STM. With increasing temperature the ripples vanish. They are not removed by a reduction of the amplitude, but by the creation of circular voids. Inside these voids the surface exhibits few steps and is otherwise flat on an atomic scale. In the middle of the voids Cu clusters are found, which appear at steps. Inside the crystalline area of the voids the Si(111) "quasi 5×5" Cu surface is found. For larger temperatures the number and size of these voids increases until the ripples are removed from the whole surface.

Focused ion beam (FIB) techniques are one way to modify locally the properties of magnetic thin films. In previous works it was demonstrated that focused-ion-beam irradiation causes a considerable grain growth in magnetic thin films under certain conditions and therefore a change of their magnetic properties [1]. Although the grain growth can be already qualified by simple REM images a crystallographic tool is needed for a qualitative analysis. We used the advantage of nondestructive X-ray diffraction to study the grain growth.
A magnetic thin film of 50nm thick permalloy film (Fe0.2Ni0.8) sputtered on Si was used for the investigations. We have analyzed two simple parameters such as the grain size and the microstrain depending on the ion dose and beam current. Due to the very small structures created by focused-ion-beam techniques (usually less then 0.4x0.4mm2 size) an optimized X-ray laboratory setup with a focused X-ray beam of 200µm was used.
[1] C.M. Park and J.A. Bain, J. Appl. Phys. 91, 6830(2002).

This 18th century object with delicate on-glaze decorations let arise doubts regarding its complete originality. Comparing both base body and cover, the shades of porcelain glazing differ visually. Moreover, the painting shows slight differences in color and flow. Simultaneous PIXE and RBS (Rutherford Backscattering Spectrometry) using the 4-MeV proton beam in air [1] proved ideal to get convincing answers. The maximum proton beam intensity was only 200 pA for 30 s acquisition time in order to ensure non-destructive analysis of the very sensitive material.
For the green colorant of leaves of trees, painted on both bottom and cover, the artist used copper green pigment [2]. For painting the bottom of the base body Cu was the starting material; brass was certainly applied for the cover as deduced from additional Zn lines displayed by PIXE. In the latter case the green pigment was obviously brightened by the addition of Co. Pink decoration of the cover could be identified as made from purple due to small Au-L lines. They were not visible analysing the pink skirt, painted on the bottom, because of superimposed intense Pb-L lines originating from the glazing. Comparatively, the X-ray spectrum obtained from pure glazing of the cover shows much lower Pb-L intensity. RBS was helpful for getting information on the depth distributions of Pb regarding the different types of glazing. This is illustrated in the graphs below. Whereas the bottom of the porcelain box comprises thick and lead containing glazing, the RBS spectrum taken from glazing of the cover makes clear that only little Pb exists, which is localized at the glazing surface. This can be attributed to a surface polishing process carried out in the past.

References: [1] C. Neelmeijer and M. Mäder, Nucl. Instr. Meth. B 189, 293 (2002).
[2] M. Mields, Keramische Zeitschrift 8, 453 (1963).

The U(VI) sorption onto Opalinus Clay (OPA), a natural clay rock from Mont Terri, Switzerland, was investigated in the absence and presence of humic acid under aerobic conditions using synthetic OPA pore water (I = 0.34 M, pH 7.6) as background electrolyte. The results show that the U(VI) sorption onto OPA is low and not influenced by humic acid. This can be attributed to the dissolution of calcite, a mineral constituent of the clay. The resulting calcium ions (up to 25 mM) in the pore water influence both the U(VI) speciation and the speciation of humic acid. In OPA pore water the U(VI) speciation is dominated by the neutral complex Ca2UO2(CO3)3(aq) both in the absence and presence of humic acid. Its predominance was verified by time-resolved laser-induced fluorescence spectroscopy (TRLFS). Speciation estimations for humic acid show that calcium ions saturate the humic acid binding sites almost completely. Thus, only few humic acid binding sites are available for U(VI) complexation at pH 7.6. For the sorption of U(VI) and humic acid onto OPA distribution coefficients, Kd, were determined and amount to (0.0222 ± 0.0004) m3/kg and (0.129 ± 0.006) m3/kg, respectively. In conclusion, calcium ions determine the interaction processes of U(VI) and humic acid in the OPA system.

The subsurface acid mine drainage (AMD) environment of an abandoned underground uranium mine in Königstein/Saxony/Germany, currently in the process of remediation, is characterized by low pH, high sulfate concentrations and elevated concentrations of heavy metals, in particular uranium. Acid streamers thrive in the mine drainage channels and are heavily coated with iron precipitates identified as schwertmannite and jarosite. These precipitates are biomineralisations and related to the presence of Fe-oxidizing microorganisms. Such precipitates were also observed in stalactite-like dripstone, called snottites, growing on the gallery ceilings. The bacterial diversity was identified on basis of analysed 16S rDNA sequences and revealed that the beta-proteobacterium Ferrovum myxofaciens dominates. Colloidal uranium, neither as U(IV)- or as U(VI) eigencolloids nor uranium adsorbed on colloids was detected as photon correlation spectroscopy analyses and centrifugation experiments of drainage water and snottite water at different centrifugal accelerations between 500 g and 46000 g showed.
The uranium speciation in the underground AMD waters flowing in mine galleries as well as dripping from the ceiling and forming stalactite-like dripstones were studied by time resolved laser-induced fluorescence spectroscopy (TRLFS). The fluorescence lifetime of both waters were best described with a mono-exponential decay, indicating the presence of one species only. The detected positions of the emission bands and by comparing it in a fingerprinting procedure with spectra obtained for acid sulfate reference solutions, in particular Fe - SO42- - UO22+ reference solutions, indicated that the uranium speciation in the AMD environment of Königstein is dominated in the pH range of 2.5 to 3.0 by the highly mobile aquatic uranium sulfate species UO2SO4(aq) and formation of uranium precipitates is rather unlikely as is retardation by sorption processes. The presence of iron in the AMD reduces the fluorescence lifetime of the UO2SO4(aq) species from 4.3 µs found in iron-free uranium sulfate reference solutions to 0.7 µs in both AMD waters of Königstein and in iron containing uranium sulfate reference solutions, respectively. Thermodynamic calculations indicated the presence of two additional uranium species, i.e. UO2(SO4)2- and UO22+ in AMD of Königstein, however TRLFS provided no spectroscopic evidence for their existence.
TRLFS was directly applied to complex solutions of acid mine drainage (AMD) environments intimately associated with microbiology and Fe-precipitates and shows that it is a suitable spectroscopic technique to identify the uranium speciation in natural solutions containing a multitude of different complexing agents.

Copper-rich precipitates are assumed to be the main cause of hardening and embrittlement of Cu-bearing reactor pressure vessel steels since they act as obstacles to dislocation motion within the grains of polycrystalline bcc-Fe. Multiscale modeling contributes to a better understanding of point-defect-induced formation of these clusters during reactor operation. Rate theory is an efficient tool to simulate the cluster evolution on realistic time and length scales. However, many parameters used in rate theory, such as the diffusion coefficients of mobile species and the free binding energies of clusters, are not very well known from experimental investigations. Atomic-level computer simulations can provide these data.
In the present work the free binding energies are determined for small and medium-sized CunVm clusters in bcc-Fe. The most recent Fe-Cu interatomic potential by Pasianot and Malerba [1] is used. Enthalpy and entropy contributions are calculated using combinations of on-lattice Monte Carlo simulations and off-lattice molecular dynamics calculations.
[1] R. C. Pasianot and L. Malerba, J. Nucl. Mater. 360, 118 (2007).

The high-pressure induced structural phase transitions and pressure induced elastic and anharmonic behavior of boron compounds viz. BN, BP, and BAs have been investigated using an inter-ionic potential approach based on charge transfer effect. These compounds go to NaCl phase (B1) under pressure from zinc blende phase (B3). The variations of second-order elastic constants and their combinations follow a systematic trend with pressure, identical to that observed in other compounds of zinc blende structure family. Shear stiffness constants decrease with increasing pressure up to phase transition pressure. The bulk moduli of these compounds are in reasonably good agreement with other theoretical and experimental data. The values of phase transition pressure of these compounds obtained by using the present approach are also in good agreement with those predicted by using the pseudo potential approach. The present approach has also succeeded in predicting the Born and relative st!
ability criterion for stable zinc blende phase of these compounds. We also present a set of third-order elastic constants and pressure derivatives of second-order elastic constants for boron compounds.

Abstract: We present a dielectric continuum model approach for studying the electrical polarization properties of interface polarization coupled BaTiO3, BaTiO3-ZnO, and ZnO-BaTiO3-ZnO thin-film structures consisting of several hundred nanometer thick layers. Our model augments the effects of electric field driven switchable polarization and depletion layer formation with spontaneous interface polarization coupling. Wurtzite-structure (piezoelectric) n-type ZnO and perovskite-structure (ferroelectric) highly insulating BaTiO3 layers were prepared and investigated. The coupling between the nonswitchable spontaneous polarization of ZnO and the electrically switchable spontaneous polarization of BaTiO3 causes strong asymmetric polarization hysteresis behavior. The n-type ZnO reveals hysteresis-dependent capacitance variations upon formation of depletion layers at the ZnO/BTO interfaces. We obtain a very good agreement between our model generated data and our experiment. Our model approach allows for derivation of the amount and orientation of the spontaneous polarization of the piezoelectric constituents and can be generalized toward multiple-layer piezoelectric-semiconductor ferroelectric heterostructures. We identify interface polarization coupled triple-layer ZnO-BTO-ZnO heterostructures as two-terminal unipolar ferroelectric Bi-junction transistor for use in memory storage.

Resistivity of ZnO:Al (AZO) films is known to increase significantly during annealing or growth at temperatures higher than certain optimum value that is a problem during preparation of thin film solar cells. To understand this process, AZO films with different Al concentrations grown by reactive pulsed magnetron sputtering were studied. The electrical resistivity of the films shows a minimum at an optimum substrate temperature, which shifts from 400 °C to 200 °C with increasing Zn/O flux ratio. At higher temperatures, resistivity increases due to simultaneous decrease of the free electron density and mobility. It is accompanied by a significant deterioration of the film crystallinity, increase of Al concentration and drop of the growth rate. X-ray absorption near edge structures (XANES) excludes formation of aluminum oxides in this case. It shows formation of homologous phase (ZnO)3(Al2O3) whose formation is triggered by an increase of the Al/Zn ratio in the film. Therefore, at growth temperatures above the optimum value Al preferentially forms this phase instead of occupying Zn site in the lattice.

The fabrication of novel uranyl (UO2 2+) binding protein based sensors is reported. The new biosensor responds to picomolar levels of aqueous uranyl ions within minutes using Lysinibacillus sphaericus JG-A12 S-layer protein tethered to gold electrodes. In comparison to traditional self assembled monolayer based biosensors the porous bioconjugated layer gave greater stability, longer electrode life span and a denser protein layer. Biosensors responded specifically to UO2 2+ ions and showed minor interference from Ni2+, Cs+, Cd2+ and Co2+. Chemical modification of JG-A12 protein phosphate and carboxyl groups prevented UO2 2+ binding, showing that both moieties are involved in the recognition to UO2 2+.

It has been shown that increasing substrate temperature above its optimum value leads to an increase of Al concentration in the AZO films, which exceeds the solubility limit and triggers the formation of an insulating metastable homologous (ZnO)3Al2O3 phase. The formation of (ZnO)3Al2O3 is established for the AZO films grown in a given range of deposition conditions, while the films grown at substantially different conditions may show formation of other secondary phases (e.g. aluminium oxide or spinel). This (ZnO)3Al2O3 impedes crystal growth and causes a significant increase of free electron scattering. In turn, it leads to an increase of electrical resistivity of the films. This phase has been observed by XANES even in the films with the lowest Al concentration and the best crystallinity. Increase of this phase volume fraction with increasing Al concentration correlates with observed changes in the film Raman and optical constants spectra.

An overview of different configurations of spectroscopic ellipsometers was given. The approaches for data acquisition and analysis in case of high refractive index materials and transparent conductive oxides were discussed.

Understanding of the mechanisms of donor impurity incorporation, its electrical activation and charge carrier transport in transparent conducting oxides (TCO) is required for further improvement of functionality of this class of materials. The present work focuses on investigation of indium oxide (IO), Sn-doped indium oxide (ITO), ZnO, and ZnO:Al (AZO) films grown by reactive pulsed magnetron sputtering (RPMS) with a precise control of the oxygen partial pressure at substrate temperatures, Ts, ranging from RT to 550°C. In order to explore potential advantages of RPMS, the relationship between the deposition parameters and structure, phase composition and physical properties of these TCOs was investigated. The films were characterized by spectroscopic ellipsometry, Hall effect measurements, X-ray diffraction (XRD) and, in case of ZnO and AZO films, by X-ray absorption near edge structures (XANES). The Sn concentration in ITO was determined by Auger analysis, while the Al concentration in ZnO matrix was estimated by elastic recoil detection analysis and Rutherford back scattering.
The comparison of the real-time behavior of the IO and ITO film structure and electrical properties during annealing provides a direct evidence of Sn donor activation (with an estimated efficiency of 40%) in ITO due to amorphous-to-crystalline transition. The ITO film crystallinity always improves with increasing substrate temperature or during isothermal annealing, with the electrical resistivity decreasing. In contrast, the electrical resistivity of AZO films shows a clear minimum at an optimum substrate temperature (200-400 °C), which depends on metal/oxygen flux ratio and correlates with a maximum in crystallinity (grain size). In this case, the highest mobility value of 46 cm2 V-1 s-1 is comparable to the best values achieved in AZO films grown by less cost-efficient techniques. This value is achieved at the free electron density of 6x10²⁰ cm-3 which corresponds to maximum ~30% electrical activation of Al impurity. At higher temperatures, the AZO electrical properties and crystalline quality deteriorate abruptly according to the following mechanism. Increasing Ts above its optimum value leads to a higher Al concentration in the AZO films, which exceeds the solubility limit and triggers the formation of an insulating metastable homologous (ZnO)3Al2O3 phase. This phase impedes crystal growth and causes a significant increase of free electron scattering both at grain boundaries and inclusions of this phase. In order to enable the growth of low-resistivity AZO films in a wider range of TS, lower metal/oxygen flux ratios should be used. The proposed approach to minimizing the influence of this undesirable phase may also be applied to other deposition methods of AZO involving high-energy particle bombardment.

A systematic study on structural defect buildup in 320 keV Ar-ion bombarded GaN epitaxial layers has been reported, by varying ion fluences ranged from 5x10¹² to 1x10¹⁷ at/cm². 1μm thick GaN epitaxial layers were grown on sapphire substrates using the MOVPE technique. RBS\channeling with 1.7 MeV ⁴He beam was applied for analysis. As a complementary method High Resolution Transmission Electron Microscopy (HRTEM) has been used. The later has revealed the presence of extended defects like dislocations, faulted loops and stacking faults. New version of the Monte Carlo simulation code McChasy has been developed that makes it possible to analyze such defects on the basis of the Bent Channel (BC) model. Damage accumulation curves for two distinct types of defects, i.e. Randomly Displaced Atoms (RDA) and extended defects (i.e BC) have been determined. They were evaluated in the frame of the MultiStep Damage Accumulation (MSDA) model, allowing numerical parameterization of defect transformations occurring upon ion bombardment. Displaced atoms buildup is a three step process for GaN and whereas extended defect buildup is always a two step process.

In diesem Beitrag werden ausgewählte tomographische Bildgebungsverfahren vorgestellt, die in den zurückliegenden Jahren am Forschungszentrum Dresden-Rossendorf für die Untersuchung von Mehrphasenströmungen entwickelt wurden. Neben einer Beschreibung der Messverfahren wird ihre Anwendung in der experimentellen Thermofluiddynamik und ihr Bezug zur Entwicklung und Validierung von CFD-Modellen für Zweiphasenströmungen diskutiert.

Two neurotensin(8-13)-containing peptide heterodimers were prepared via copper(I)-mediated click chemistry. The resulting peptide dimers could be obtained in 28-31% yield after HPLC purification. Neurotensin( 8-13)-containing peptide dimers were used in an in vitro binding assay to determine binding affinity towards the neurotensin receptor-1 (NTR1). The determined IC₅₀ values of 8.3 µM and 0.7 µM indicate only very low binding affinity of the neurotensin(8-13)-containing peptide heterodimers towards the NTR1.

We studied the angular dependence of the ferromagnetic resonance (FMR) spectra of (0001)ZnO single crystals implanted with Ni and Fe ions and compared the results to the data obtained by other experimental techniques, especially, x-ray diffraction (XRD) and superconducting quantum interference device magnetometry. The FMR revealed the formation of metal nanocrystals (NCs) embedded in the ZnO lattice in an oriented way. Whereas in the case of Ni, the conclusions drawn from the FMR studies corroborated the XRD and magnetometry results with respect to the alignment of the NCs in the host lattice, in the case of the Fe NCs, the FMR clearly shows that the hard magnetization axis (which is < 111 > in bcc Fe) is oriented perpendicular to the sample surface (parallel to the [0001]ZnO axis), at variance with the former XRD observations.

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kein Abstract verfügbar

G-Protein coupled receptors (GPCRs) play a fundamental role in many physiological processes. High ligand specifity of rhodopsin-like GPCRs in contrast to the highly conserved and class defining D(E)RY motif undergoing a protonation upon receptor activation suggests a general local activation mechanism acting as an autonomous functional module.
It has been shown that the D(E)RY motif positioned at the phase boundary acts as a pH-dependent switch which is governed by side chain partitioning between the aqueous and lipidic phase [1].
Here we have addressed the putative reverse effect, i.e. restructuring of the water lipid interface upon side chain protonation to elucidate the functional implication of water lipid protein interactions in the control of protein conformation. We have studied a TM3 derived transmembrane segment where a fluorescence reporter resides below the D(E)RY motif inside the helix. By fluorescence spectroscopy, FRET studies and FTIR-Fluorescence cross correlation experiments we show the pH dependent hydration site N-terminally of the D(E)RY motif. Thus the ionized D(E) side chain attracts water that dissolves the TM-sequence even beyond the two preceding hydrophobic residues.
These results argue for a key role of the rearrangement of the water lipid protein microstructure upon GPCR activation as it effects not only the phase boundary but even more hydrophobic environment inside the lipidic phase.
[1] S. Madathil, K.Fahmy, J Biol Chem 284, 28801-28809 (2009)

Stratified two-phase flow regimes can occur in the main cooling lines of Pressurized Water Reactors, Chemical plants and Oil pipelines. A relevant problem occurring is the development of wavy stratified flows which can lead to slug generation. In the last decade, the stratified flows are increasingly modelled with computational fluid dynamics (CFD) codes. In CFD, closure models are required that must be validated. The recent improvements of the multiphase flow modelling in the ANSYS CFX code make it now possible to simulate these mechanisms in detail. In order to validate existing and further developed multiphase flow models, high-resolution measurement data is needed in time and also in space. For the experimental investigation of co-current air/water flows, the HAWAC (Horizontal Air/Water Channel) was built. The channel allows in particular the study of air/water slug flow under atmospheric pressure. Parallel to the experiments, CFD calculations were carried out. The two-fluid model was applied with a special turbulence damping procedure at the free surface. An Algebraic Interfacial Area Density (AIAD) model on the basis of the implemented mixture model was introduced, which allows the detection of the morphological form of the two phase flow and the corresponding switching via a blending function of each correlation from one object pair to another. As a result this model can distinguish between bubbles, droplets and the free surface using the local liquid phase volume fraction value. The behaviour of slug generation and propagation was qualitatively reproduced by the simulation, while local deviations require a continuation of the work. The creation of small instabilities due to pressure surge or an increase of interfacial momentum should be analysed in the future. Furthermore, experiments with pressure and velocity measurements are planned and will allow quantitative comparisons at other superficial velocities.

The control of the effective magnetic anisotropy, saturation magnetization, as well as the dynamic magnetic properties in ferromagnetic thin films is of significant importance for most applications in spin electronics. Usually the magnetic anisotropy, e.g. uniaxial anisotropy or unidirectional anisotropy, in ferromagnetic single or multi-layers is initialized by applying a magnetic field during film deposition or by a magnetic field anneal, which results in an anisotropy aligned along the applied field direction. The saturation magnetization is mainly determined by the film's composition. Whereas anisotropy and saturation magnetization together determine the precessional frequency of the films, the magnetic damping parameter cannot easily be varied in a controlled way.
Here we give a summary on different ways to pattern magnetic films in terms of laterally varying magnetic properties and not by shape patterning [1]. Different samples of anisotropy [1,2], exchange bias [1,3], and saturation magnetization [4] modulated thin films are prepared by local oxidation, introducing local stress variation [5], and local ion irradiation or implantation. The magnetization reversal processes in the two-phase materials exhibit unique features, some of them so far only known from multilayer samples. The main emphasis of the investigations is on the role of magnetic domain formation and domain wall effects in stripe-like magnetic hybrid structures on the overall static and dynamic magnetic properties.
The presented paths of film preparation provide an additional degree of freedom for the tailoring of magnetic properties and functionality of soft-magnetic thin films.

Traumatic brain injury is a leading cause of death and disability in children. Studies using adult animal models showed alterations of the central cholinergic neurotransmission as a result of trauma. However, there is a lack of knowledge about consequences of brain trauma on cholinergic function in the immature brain. It is hypothesized that trauma affects the relative acetylcholine esterase activity and causes a loss of cholinergic neurons in the immature brain. Severe fluid percussion trauma (FP-TBI, 3.8 0.3 atm) was induced in 15 female newborn piglets, monitored for 6 h and compared with 12 control animals. The hemispheres ipsilateral to FP-TBI obtained from seven piglets were used for acetylcholine esterase istochemistry on frozen sagittal slices, while regional cerebral blood flow and oxygen availability was determined in the remaining eight FP-TBI animals. Post-fixed slices were immunohistochemically labelled for choline acetyltransferase as well as for lowaffinity neurotrophin receptor in order to characterize cholinergic neurons in the basal forebrain. Regional cerebral blood flow and brain oxygen availability were reduced during the first 2 h after FPTBI (P < 0.05). In addition, acetylcholine esterase activity was significantly increased in the neocortex, basal forebrain, hypothalamus and medulla after trauma (P < 0.05), whereas the number of choline acetyltransferase and low-affinity neurotrophin receptor positive cells in the basal forebrain were unaffected by the injury. Thus, traumatic brain injury evoked an increased relative activity of the acetylcholine esterase in the immature brain early after injury, without loss of cholinergic neurons in the basal forebrain. These changes may contribute to developmental impairments after immature traumatic brain injury.

Aims: Traumatic brain injury (TBI) is one of the leading causes of death and disability in children. Adult animal models of TBI showed cholinergic alterations. However, there is no comparable data on immature animals. Therefore, this study investigates cholinergic markers in a large animal model of juvenile TBI. Methods: Twenty-seven female newborn piglets were subjected to lateral fluid percussion (FP) injury and compared with 12 untreated animals. After 6 h, animals were sacrificed and the brains removed.The hemispheres ipsilateral to FP-TBI from seven piglets and corresponding hemispheres from six control animals were used for autoradiography. Receptor density was determined with [3H]epibatidine (nicotinic acetylcholine receptors) or [3H]QNB (muscarinic acetylcholine receptors). The density of the vesicular acetylcholine transporter (vAChT) was assessed with (-)-[3H]vesamicol. Cerebral blood flow was measured by coloured microsphere method. Results: Cerebral blood flow and brain oxygen delivery were transiently reduced early after FP-TBI (P < 0.05). TBI caused reductions of muscarinic acetylcholine receptor density (fmol/mg) in the basal forebrain (sham: 10797 1339, TBI: 8791 1031), while nicotinic acetylcholine receptor remained stable. Significant increases in vAChT density (fmol/mg) were observed in the basal forebrain (sham: 2347 171, TBI: 2884 544), putamen (sham: 2276 181, TBI: 2961 386), cortex (sham: 1928 262, TBI: 2377 294), thalamic areas (sham: 2133 272, TBI: 2659 413), hippocampus (sham: 2712 145, TBI: 3391 501) and hypothalamus (sham: 2659 139, TBI: 3084 304). Conclusions: Cholinergic markers are altered after mildto- moderate TBI in the immature brain.Whereas the ACh receptors are stable in almost any brain region after TBI, vAChT expression increases after trauma at the employed severity of this specific trauma model.

Für die Veranstaltung wurden keine Abstracts eingereicht.

Vorgestellt wurden TRLFS-Studien mittels Eu(III) an Systemen aus Huminstoff und Al(III) verschiedenen Alters. Innerhalb des untersuchten Zeitraums von ca. 2 Tagen wurde eine Zunahme im Konkurrenzeffekt von Al(III) bezüglich der Huminstoff-Komplexbildung anderer Metalle festgestellt. Ziel der spektroskopischen Messungen war ein Nachweis struktureller Veränderungen am Huminstoff, die den beobachteten Effekt erklären. Zwar konnte gezeigt werden, dass durch die Komplexbildung von Al(III) erhebliche Veränderungen in der Mikroumgebung des Sondenmetalls Eu(III) induziert werden. Diese entsprachen jedoch nicht dem zeitlichen Trend im Konkurrenzeffekt. Aus Spektrenanalysen ging hervor, dass ein solcher Trend bei der relativ hohen Konzentration des Sondenmetalls gar nicht auftritt.
Gezeigt wurden auch erste PET-Untersuchungen zum diffusiven Transport in einem Opalinuston-Bohrkern. Mit Hilfe verbesserter Korrekturverfahren und neuer Visualisierungstechniken konnte die Methodik erheblich voran gebracht werden. Bereits nach einer Versuchsdauer von 2 Wochen konnte ein Diffusionskoeffizient abgeschätzt werden, der in Übereinstimmung mit Literaturdaten stand. Die Erfassung räumlicher Inhomogenitäten im Ausbreitungsverhalten erfordert jedoch längere Messzeiten und einen modifizierten Versuchsaufbau, welcher ebenfalls vorgestellt wurde.

kein Abstract verfügbar

In order to shed more light on the role of magnetic gradient forces and Lorentz forces on the deposition pattern found recently at copper electrodes, experiments and numerical simulations have been performed in a generic geometry that consists of a single small cylindrical permanent magnet which is placed behind the cathode. The cylinder axis coincides with the magnetization direction and points normal to the electrode surface. The electrode is oriented vertically which allows a separate discussion of the influence of both forces.

Experiments and numerical simulations are found to give very good agreement with respect to the deposition pattern. Our analysis clearly shows that the major influence is due to the action of the magnetic gradient force. Numerical simulations prove that the separate action of the Lorentz force does not reproduce the deposition structure. A detailed analytical discussion of the motion forced by the different magnetic forces in superposition with natural convection is given.

Positronen-Emissions-Tomographie (PET) wurde als Methode zur Untersuchung von Transportvorgängen in Bohrkernen aus dem Salinargestein und seinem Deckgebirge in Staßfurt eingesetzt. Die Ergebnisse dienen der Verbesserung des Verständnisses der hydraulischen und chemischen Prozesse im heterogenen, teils dichten Material. Es kann anhand von Beispielen gezeigt werden, dass diese Prozesse sich nicht allgemein durch einfache Modelle beschreiben lassen.

Strontium titanate (STO) is a preferred substrate material for functional oxide growth, whose surface properties can be adjusted through the presence of Ruddlesden–Popper (RP) phases. Here, density functional theory (DFT) is used to model the (1 0 0) and (0 0 1) surfaces of SrO(SrTiO3)n RP phases. Relaxed surface structures, electronic properties and stability relations have been determined. In contrast to pure STO, the near-surface SrO–OSr stacking fault can be employed to control surface roughness by adjusting SrO and TiO2 surface rumpling, to stabilize SrO termination in an SrO-rich surrounding or to increase the band gap in the case of TiO2 termination. RP thin films have been epitaxially grown on (0 0 1) STO substrates by chemical solution deposition. In agreement with DFT results, the fraction of particular RP phases n = 1–3 changes with varying heating rate and molar ratio Sr:Ti. This is discussed in terms of bulk formation energy.

In YMn2O5 the Mn atoms occupy two non-equivalent Wyckoff sites within the unit cell exhibiting different oxygen coordinations, i. e. the system can be characterized as a mixed-valence compound. For the formation of the orthorhombic crystal structure Jahn-Teller distortions are assumed to play an important role. In this study, we aimed at the investigation of the crystal structure on the substitution of Mn by the non-Jahn-Teller cation Fe+3. Therefore, we synthesized a series of YMn(2-x)FexO5 powder samples with x = 0; 0:5; 1 by a citrate technique. We utilized extended x-ray absorption fine structure (EXAFS), x-ray absorption near edge structure (XANES) analysis and Density Functional Theory to investigate the two non-equivalent Wyckoff sites within the orthorhombic crystal structure (confirmed for all compositions) occupied by transition-metal atoms. For quantitative determination of structural short-range order firstly all plausible options of substitution of Fe for Mn were discussed. On basis of these evaluations the EXAFS and XANES behavior was analyzed and appropriate crystallographic weights were assigned to the subset of structural models in accordance with the experimental data. From EXAFS analysis, using multiple scattering theory, we concluded only the 4h Wyckoff site to be occupied by Fe (occupancy refined was (100 +- 3)% in case of x = 1). Furthermore, taking the XANES spectra into account, we could verify the EXAFS results and additionally explain the differences in the Mn-K XANES spectra in dependence on x to be caused by changes of the dipole transitions to 4p final states. Since only one Wyckoff site is involved the experimentally observed limit to a maximum amount of x = 1 is explained. Additionally, a possible disorder, discussed in the literature, was not proven for our samples. With DFT calculations the experimental findings were verified on base of the total energy of the different possible electronic configurations. Crystal field effects were identified to be responsible for the site selective substitution of Fe for Mn.

A new measurement of subthreshold K∗(892)0 and K0 production is presented. The experimental data complete the measurement of strange particles produced in Al + Al collisions at 1.9AGeV measured with the FOPI detector at SIS at GSI (Darmstadt). The K∗(892)0/K0 yield ratio is found to be 0.0315 ± 0.006(stat.) ± 0.012(syst.) and is in good agreement with the transport model prediction. These measurements provide information on the in-medium cross section of K+-π− fusion, which is the dominant process in subthreshold K∗(892)0 production.

The monitoring and visualization of two-phase flow is of great importance either from technical/practical point of view for process control and supervision or from scientific/theoretical point of view, for the understanding of physical phenomenon. A wire-mesh sensor was applied to experimentally investigate two-phase horizontal pipe flow. Furthermore, some physical flow parameters were extracted based on the raw measured data obtained by the sensor. In this article, first the work principle of wire-mesh sensors is revised and second the methodology of flow parameter extraction is described. A horizontal flow test section comprising of a pipe of 26 mm i.d. 9 m long was employed to generate slug flows under controlled conditions. A 8 × 8 wire-mesh sensor installed at the end of the test section delivers cross-sectional images of void fraction. Based on the raw data, mean void fraction, time series of void fraction and characteristic slug frequency are extracted and analyzed.

Course in Mixing, Multiphase flow, and Turbulence modelling

Sektion 2 Thermo- und Fluiddynamik / Thermodynamics and Fluid Dynamics
Sitzung: Numerische Strömungsberechnung
Die Leitung der Sitzung hatte Herr Dr. Th. Höhne vom Forschungszentrum Dresden- Rossendorf e.V., Dresden inne.

The deposition of Ni-Ti films with definite stoichiometry and high purity remains still a challenge. Furthermore, important issues like the formation of film texture and its control are not yet resolved. Near equiatomic (~ 50.0 at.% Ti¨CNi) and Ti-rich (~ 50.8 at.% Ti¨CNi) Ni-Ti polycrystalline films (thickness values ¡Ü 800 nm) have been deposited by magnetron co-sputtering using a chamber installed into the six-circle diffractometer of the Rossendorf beamline at the European Synchrotron Radiation Facility. The in-situ X-ray diffraction studies enabled the identification of different steps of the structural evolution during films processing. Films exhibiting a (100) preferential orientation for the B2 phase have been successfully produced. A continuous increase of the B2(200) diffraction peak intensity has been observed for depositions on a 140 nm amorphous SiO2 buffer layer heated at 520¡ãC (without substrate bias voltage, Vb). A (100) texture has been observed for films as thick as 800 nm. Films deposited without and with Vb on a TiN coating with a topmost layer formed by <111> oriented grains have shown a preferential growth of <110> oriented grains of the B2 phase from the beginning of the deposition. Those trends have been observed for the growth of near equiatomic and Ti-rich films.

Positron-Emission-Tomography (PET) enables direct and quantitative monitoring of the spatio-temporal distributions of dissolved inert and/or reactive PET-nuclides and PET-nuclide-labeled colloids during their passage through decimeter-scaled material samples. We apply PET exclusively to geomaterial samples and reach the physical resolution limit of about 1 mm with our small-animal-PET scanner (ClearPET, Raytest). We suggest our GeoPET has unrivalled sensitivity and selectivity for our tracer concentrations to some 107 tracer atoms/µl and thus is ideally suited for direct flow and transport process observations in geomaterials. This lower limit of the tracer concentration in the order of about 1 kBq/µl outranges other process observation methods (e.g. NMR or resistivity tomography) by many orders of magnitude. Like in the common medical practice, a combination with µCT for structural imaging would be advantageous for improving the spatial significance.
In the past we demonstrated the feasibility of the method, applying in-house developed and medical PET-scanners (Richter et al., 2003, Gründig et al., 2007). The installation of ClearPET in our controlled area made possible long-term experiments, like diffusion of long-living PET-tracers (like 58Co, decay time 71 days) and flow observations over several days (with 124I-labelled compounds, decay time 4 days) (Kulenkampff et al. 2008, Wolf 2010). The installation of a new cyclotrone will extend the availability of short-living PET-isotopes for fast process observations (e.g. 11C, decay time 20 min).
The density of geomaterials may cause more than 50% of Compton-scattered events, which degrade image quality mainly by inhomogeneous reconstruction artifacts. These artifacts caused explicitly by geomaterials (and only insignificantly in medical applications) are currently being addressed by model-based scatter-correction procedures.
Application examples include the fluid flow visualization in saliniferous rock cores. Different types of flow regimes are identified: in rather dense and low porous rock samples we observe slowly propagating diffuse “clouds of tracer”, whereas in fractured halite and sandstone samples (Fig. 1) we identified networks of extremely localized pathways, each with locally varying propagation velocities (Fig. 2). Quantitative parameterization of pathway and velocity distributions is possible, but still pending. However, with GeoPET-process observations we are capable of evaluating the results of Lattice-Boltzmann simulations, based on structural information from voxel-wise segmented µCT of the same sample. With respect to localized pathways in the fracture system of the halite, the model yields comparable results.
Nevertheless, even the high resolution of µCT may be insufficient to visualize the pore-space characteristics in tighter material, and more complex compositions may impair segmentation results from µCT-images. Then, stochastic models which are generated from other information, like pore-size distributions (with missing network information) and integral transport parameters (with missing distribution information), can still be validated by comparing model results with GeoPET-observations.

The plasma-immersion ion implantation (PIII) technique was used to modify and improve the surface of a Ni-Ti alloy (» 50.2 at.% Ni) for biomedical applications. The main goal has been the formation of a Ni-depleted surface, which should serve as a barrier to out-diffusion of Ni ions from the bulk material. Ion implantation of oxygen was carried out. The depth profiles of the elemental distribution in the alloy surface region, obtained by Auger electron spectroscopy (AES), confirm the formation of a Ti-rich oxide layer. The working plan also comprised ion implantation of nitrogen. In this case, the formation of titanium oxynitride (TiNxOy) was observed. The AES depth profiles clearly show a Ni-depleted fraction for experiments performed with 40 keV.

Beside salt dome and granite rock, also clay rock is discussed as a possible host rock for siting a nuclear waste repository in Germany. The focus of the present work is the investigation of the U(VI) interaction with Opalinus Clay from Mont Terri, Switzerland, used here as a generic test case for studying radionuclide-clay interaction. The influence of humic acid (HA), a representative of natural organic complexing agents, on the migration of U(VI) is studied in addition.
U(VI) sorption experiments with ground Opalinus Clay and U(VI) diffusion experiments with intact clay rock were performed in the absence and presence of HA using synthetic Opalinus Clay pore water (I = 0.36 M, pH 7.6; [1]) as the background electrolyte. It was found that the U(VI) sorption onto Opalinus Clay is low and it is not influenced by HA. Speciation calculations showed that, under pore water conditions, Ca2UO2(CO3)3(aq) [2] is the dominant U(VI) species in solution both in the absence and presence of HA. The U(VI) speciation is not influenced by HA, which is predominantly present as a Ca complex [3]. It can be concluded, that calcium ions released by the dissolution of calcite (13% of Opalinus Clay [4]) play an important role in the investigated system.

[1] F.J. Pearson, PSI Internal report TM-44-98-07, Paul Scherrer Institut, Villigen PSI, Switzerland, 1998.
[2] G. Bernhard, G. Geipel, T. Reich, V. Brendler, S. Amayri, H. Nitsche, Radiochim. Acta 89 (2001) 511.
[3] A. Paulenová, P. Rajec, M. Žemberyová, G. Sasköiová, V. Višacký, J. Radioanal. Nucl. Chem. 246 (2000) 623.
[4] Nagra, Nagra Technical Report NTB 02-03, Wettingen, Switzerland, 2002, p. 230.

kein Abstract verfügbar

C₁₄H₁₂FNO, monoclinic, P2₁/n (no. 14), a = 5.6653(2) Å,
b = 25.305(1) Å, c = 8.2832(3) Å, ß = 92.237(3)°,
V = 1186.6 ų, Z = 4, R_gt(F) = 0.047, wR_ref(F²) = 0.123,
T = 173 K.

Click chemistry has received considerable attention as powerful modular synthesis approach, which has found numerous applications in many areas of modern organic chemistry, drug discovery and material science. Recently, click chemistry, and in particular the copper-mediated 1,3-dipolar [3+2] cycloaddition between azides and alkynes, has also entered the field of radiopharmaceutical sciences. This review addresses the recent developments of click chemistry for the synthesis of various radiotracers for molecular imaging purposes. Click chemistry-based radiotracers that will be covered include peptides and small organic molecules containing the short-lived positron emitters fluorine-18, and the gamma-emitters technetium-99m, indium-111, and iodine-125.

The natural volcanic glass obsidian was an important raw material for tools and arms during prehistoric time and has been found by researchers at great distances from potential natural sources. Reliable provenancing can provide evidence of contacts over a certain dis-tance and information about exchange patterns and mobility of prehistoric people.
Instrumental Neutron Activation Analysis (INAA) is one of the major analytical techniques to solve the problem of obsidian provenancing by means of its highly specific chemical composition, the “chemical fingerprint” [1-4]. The advantages of bulk INAA are the absence of matrix effects, the large number of ele-ments simultaneoulsy detectable, its sensitivity and accuracy. However, INAA is limited as being destruc-tive and inclusions cannot be distinguished from the matrix applying routine analytical practice.
Additional application of non-destructive Ion Beam Analysis (IBA), consisting of Proton Induced X-ray Emission (PIXE), Proton Induced Gamma-ray Emission (PIGE) and Rutherford Backscattering Spectrometry (RBS), supplement INAA measurements by enabling systematic spatially resolved surface investigations and adding a complementary element spectrum [5-9]. Furthermore, a comparison of chemical compositions obtained by different analytical methods provide the actual degree of the reliability of the analytical results [10].
For this study, both INAA and IBA measurements have been applied to the same samples to gain a more complete set of elements and to check the self-consistency of the analytical results. The samples originate from the obsidian sources Demenegakion and Agia Nychia (Cape Bombarda) on the island of Melos (Greece) (Fig. 1). Our INAA studies have been performed at the TRIGA MkII 250 kW research reactor of the Atominstitut in Vienna, where 150 mg of ground aliquots have been irradiated for 1 min at a thermal neutron flux of 3.3x10¹²cm^-2s^-1. IBA measurements have been carried out using the 4 MeV proton beam in-air of the 5 MV tandem accelerator of the Ion Beam Centre of FZD [9,11].

Fig. 1: Geographical situation of obsidian sources on the island of Melos (after [12]).

Our investigations are part of a joint project to apply selected analytical methods, in particular INAA, IBA and Inductively Coupled Plasma-Mass Spec-trometry (ICP-MS), to reveal a maximum of compositional differences between easily available samples of the natural obsidian sources in Europe. This knowledge should enable to decide, which least invasive analytical method should be chosen for the analysis of a specific highly valuable archaeological artefact, on a case by case basis.

References: [1] Meloni S. et al. J. Radioanal. Nucl. Chem. 271 (2007) 533-539. [2] Arias A. et al. J. Radioanal. Nucl. Chem. 268 (2006) 371-386. [3] Kilikoglou V. et al. J. Archaeol. Sci. 23 (1996) 343–349. [4] Aspinall. A. et al. Nature 237 (1972) 333–334. [5] Bellot-Gurlet L. et al. C. R. Palevol 7 (2008) 419–427. [6] Calligaro T. X-Ray Spectrometry 37 (2008) 169–177. [7] Lugliè C. et al. C. R. Palevol 5 (2006) 995–1003. [8] Kim J.C. et al. IPPA Bull. 27 (2005) 122–128. [9] Bugoi R. and Neelmeijer C. NIMB 226 (2004) 136-146. [10] Hancock R.G.V. and Carter T. J. Archaeol. Sci. 37 (2010) 243–250. [11] Saminger S. et al. J. Radioanal. Nucl. Chem. 245 (2000) 375-383. [12] Higgins M. and Higgins R. (1996) A geological companion to Greece and the Aegean Cornell University Press.

The superconducting radio frequency photo-injector (SRF gun) is one of the latest applications of superconducting RF technology in the accelerator field. Since superconducting photocathodes with high quantum efficiency are still unavailable, normal conducting cathode material is the main choice for SRF photo-injectors. However, the compatibility between the photocathode and the cavity is one of the challenges for this concept. Recently, a SRF gun with Cs2Te cathode has been successfully operated in Forschungszentrum Dresden-Rossendorf (FZD). In this paper, we will present the physical properties of Cs2Te photocathodes in the SC cavity, such as the quantum efficiency, the life time, the rejuvenation, the charge saturation and the dark current.

Einleitung: Die quantitative Elementanalytik von Schichten und Schichtabfolgen im Dickenbereich we-niger Nanometer ist in den letzten Jahren in den Fokus aktueller Forschung gerückt. Im Mittelpunkt dieser materialwissenschaftlichen Fragestellungen steht die Bestimmung von Tiefenverteilungen von Elementen in dünnen Schichten, die durch spezielle Abscheidever-fahren oder nachfolgende Prozessschritte wie Temperung erzielt werden, aber auch der Nachweis unbeabsichtigter Kontamination in den Schichten. Daraus können Informationen im Hinblick auf gezielte Materialentwicklung gewonnen werden und die Qualität bestehender Prozessführungen lässt sich bewerten.
Ionenstrahlanalyse: Mittels Ionenstrahlanalyseverfahren kann die Zusammensetzung einer Probe angefangen von der Oberfläche bis in eine bestimmte Tiefe des Materials quantitativ untersucht werden. Hierzu werden auf die zu untersuchende Probe Ionen mit einer definierten Energie (2-40 MeV) geschossen und die Streuprozesse zur Analyse genutzt. Da die Wahrscheinlichkeit für einen bestimmten Prozess (Wirkungsquerschnitt) bekannt ist, ergibt sich aus deren absoluten Häufigkeit die Konzentration aller Elemente. Im Gegensatz zu den meisten konventionellen (nicht nuklearen) Analyseverfahren sind daher zur Quantifizierung der Ergebnisse keine Messungen gegen Referenzmaterialien gleicher Matrix notwendig.
Auf dem Weg durch die Probe verlieren die Ionen durch inelastische Stöße mit Elektronen und Kernen der Atome der Matrix kontinuierlich Energie. Diese weglängenabhängige Energieabgabe (Bremsvermögen) kann berechnet und damit die chemische Zusammensetzung der Probe tiefenabhängig bestimmt werden. Abhängig von der Anfangsenergie und Art der Ionen können Tiefen bis zu wenigen Mikrometern untersucht werden.
Subnanometer Tiefenauflösung: Mit konventionellen Ionenstrahlanalysemethoden sind Tiefenauflösungen im Bereich von Atommonolagen (< 1 nm) nicht zu erreichen. Hierzu ist eine Modifizierung des klassischen Messaufbaus notwendig. Am Forschungszentrum Dresden-Rossendorf (FZD) kommen hierbei Magnetspektrometer in Kombination mit den Ionenstrahlanalyseverfahren Rutherford-Rückstreu-Spektrometrie (RBS) und Elastische Rück-streuanalyse (ERD) zum Einsatz. Mittels dieser Erweiterung muss die tiefenbestimmende Energie nicht mit einem limitierenden Energiedetektor gemessen werden, sondern kann aufgrund der Lorentzkraft aus dem Flugradius im Magnetfeld der Magnetspektrometer ermittelt werden. Allein mittels dieser Erweiterung können oberflächennah Monolagen verschiedener Elemente bestimmt werden (s. Abb. 1).

Abb. 1: Sauerstoffkonzentration eines SiO2-Multischicht-systems bestimmt mittels konventioneller ERD und ERD im “high-resolution”-Mode (HR-ERD).

Wasserstoff: Eine Ausnahme bildet das leichteste Element: Wasserstoff. Dieses Element kann mittels Kernreaktionsanalyse (NRA) über die resonante Kernreaktion 1H(15N,αγ)12C ermittelt werden. Die Tiefenabhängigkeit ergibt sich hierbei ebenfalls aus inelastischen Stößen beim Durchqueren der Stickstoffionen durch die Probe bis zum Ort der Kernreaktion.
Performance: RBS, ERD und NRA können in der Regel zerstörungsarm durchgeführt werden. Bei einigen Matrices kann allerdings der Ionenbeschuss bei hohen Fluenzen durch Diffusionsverlust oder Sputtering zum Verlust des Analyten führen und limi-tiert so die Nachweisgrenze (s. Tab. 1). Bei der Durch-führung der RBS und ERD im „high-resolution“-Mode (HR-RBS / HR-ERD) muss zur exakten Quantifizierung das Auftreten wechselnder Ionenladungszustände berücksichtigt werden. Alle Ionenstrahlanalysemethoden können zudem mit lateraler Auflösung im Mikrometerbereich (Mikrosonde) durchgeführt werden.

Tab. 1: Performance der Ionenstrahlanalysemethoden mit und ohne „high-resolution“-Mode (HR) am FZD.
Analyt Tiefen-auflösung [nm] Nachweis-grenze [at%] max.
Analysen-tiefe [nm]
RBS > Si ≈ 15 0,01 1000
HR-RBS > Si < 1 1 20
ERD ≤ Si ≈ 20 0,01 500
HR-ERD ≤ Si < 1 1 20
NRA H (F) ≈ 1 0,02 2000

We present the current status of the laser cooling experiment using relativistic C3+ ion beams at the Experimental Storage Ring (ESR) at GSI.
Based on the results of two previous beam times we show that with modern laser systems and new optical diagnostics all-optical cooling of an ion beam can be achieved and ion beam properties can be measured with high accuracy. Laser cooling can become an important tool for high-energy storage rings, because, unlike other beam cooling methods, laser cooling provides a cooling force that grows stronger for increasing beam energy.

Electroluminescence in SiO2 layers can be created by Ge implantation and a subsequent heat treatment, which forms Ge nano-particles inside the SiO2. An additional implantation of Er, connected with a further annealing, led to an improvement of the luminescence properties. However, with exceeding an optimum concentration of the Er doping the intensity of the electro-luminescence was found to be drastically decreased.
Slow positron spectroscopy (single Doppler broadening (DB) and coincidence DB) was applied in order to probe ongoing processes at a microscopic level and, in particular an impact on the optical response depending on the concentration of rare earth Er. It could be shown that the increasing intensity of the electro-luminescence is connected with a crystalline structure of the SiO2 covering the nano-particles and the improved reverse energy transfer process between Er and Ge. Obtained positron annihilation results will be compared with Transmission Electron Microscopy investigations [1] and with conclusions in recently published papers [2, 3].

[1] A. Kanjilal, L. Rebohle, M. Voelskow, W. Skorupa, M. Helm
J. Appl. Phys. 106, 026104 (2009)
[2] C.L. Heng, E. Chelomentsev, Z.L. Peng, P. Mascher, P.J. Simpson
J Appl. Phys. 105, 014312 (2009)
[3] R.S. Yu, M. Maekawa, A. Kawasuso, T. Sekiguchi, B.Y. Wang, X.B. Qin, Q.Z. Wang
NIMB 267, 3097 (2009)

Transition metal oxides show a variety of interesting properties and attract wide attention because of a broad application potential. At the same time, oxides often exhibit a complex defect structure comprising vacancy-like defects and positron annihilation can be effectively used to investigate and, thereby, to understand such structures. In this contribution, we concentrate on two oxides, namely these are zinc oxide (ZnO) and yttria stabilized zirconia (YSZ), the latter being a solid solution of an appropriate amount of yttria (Y2O3) in zirconia (ZrO2). As hydrogen has been detected in both these oxides and its content is not negligible [1,2], we also deal with positron characteristics of H-related defects, in addition to ‘bare’ vacancies. The structure of studied defects is obtained using an ab initio computational technique. Since there is a large charge transfer between oxygen and transition metal atoms in oxides, self-consistent calculations including positron induced forces are necessary to determine reliably positron characteristics.
As for ZnO, we discuss briefly the structure of studied vacancy-like defects. Then, the results of positron lifetime calculations are shown and compared with experimental data. Next, we present calculated formation energies of the same defects. We conclude that all calculated data support idea that in hydrothermally grown ZnO positrons annihilate in Zn vacancy-hydrogen complexes. Concerning YSZ, due to yttria doping a significant amount of O vacancy-yttrium complexes is present. Despite of earlier assumptions our calculations indicate that such complexes do not constitute positron traps. We further concentrate on the Zr vacancy and its complexes with hydrogen. First results for positron calculations with positron induced forces are presented. Calculated positron lifetimes are compared with experimental data, which suggests that the Zr vacancy and its complexes with hydrogen could be responsible for positron trapping in YSZ. Finally, further prospects of positron studies of defects in oxides are outlined.

[1] G. Brauer et al., Phys. Rev. B 79, 115212 (2009)
[2] O. Melikhova et al., Mat. Res. Symp. Proc. 1216, W07-10 (2010)