Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

System L amino acid transport is increased in various types of cancer. The new positron emission tomography (PET) tracer 3-O-methyl-6-¹⁸F-fluoro-L-DOPA (OMFD) is mainly accumulated via the system L and could serve to image cancer in vivo. However the differentiation between tumor and inflammatory reaction in tissues is often complicated. Therefore, we studied in vitro the accumulation mechanisms of OMFD in model systems of human tumors and inflammation, respectively. It is suggested that the high uptake of amino acid tracers is primarily caused by the higher transporter expression in tumors when compared to other tissues, e.g., inflammatory cells.
As previously shown, the subtype L-type amino acid transporter 1 (LAT1) is playing a key role of L amino acid transport in tumor cells. The functional LAT1 is a heterodimeric complex comprising a single membrane-spanning catalytic light chain protein (hLAT1) and the heavy chain of 4F2 antigen (h4F2hc), which are covalently linked via a disulfide bond.
For molecular characterization of L-type amino acid transporters focusing on the hLAT1-h4F2hc subtype quantitative RT-PCR was performed using the two different human tumor cell lines FaDu (squamous cell carcinoma) and HT-29 (colorectal adenocarcinoma). In comparison, phorbol ester stimulated THP-1 cells (a human monocyte/macrophage cell line) representing inflammatory cells were used. In vitro uptake assays were performed with HT-29, FaDu and THP-1 cells with OMFD under physiological amino acid concentrations.
OMFD demonstrated a saturable and sodium- and energy-independent accumulation in vitro in the different tumor cell lines, suggesting its uptake to be mediated mainly by sodium-independent LAT1. However, OMFD showed a significantly higher uptake in tumor cells when compared to inflammatory cells.
Our data demonstrate that OMFD could be a promising PET tracer for imaging of specific amino acid transport via LAT1 in tumors and, furthermore, for possible differentiation of tumorigenic from inflammatory processes. In conclusion, the identification and characterization of tumor specific amino acid transporters like LAT1 will be a helpful tool for diagnosis and therapy monitoring.

Accumulation of excess abdominal visceral fat has been shown to play a crucial role in the development of cardiovascular disease and obesity-related disorders like diabetes mellitus, hyperlipidemia, and hypertension.
In the last years, rodent models have gained an important role in the investigation of adipose tissue (AT) biology and disorder. In this line, non-invasive differentiation and characterization of various AT deposits in the living animal is a current challenge. MRS at high magnetic field strength is a potential tool to learn more about the pathophysiological role of lipids in vivo.

The aim of the present study was to derive the spin-spin relaxation times T2 of 9 different proton resonances occurring in lipid spectra in vivo. With these values the correction factors M₀/M_TE (with the magnetization M_TE = M₀ x exp(-TE/T2), TE = echo time) for the peak integrals of the 9 different peaks can be calculated for specific TE. These correction factors can then be used to correct in vivo PRESS spectra to derive the true values for saturation and unsaturation of the triacylglycerols in lipids.

Localized MR spectra were generated in male Wistar rats with a 7 Tesla small animal scanner with a 30 cm bore (BioSpec 70/30, Bruker BioSpin MRI GmbH, Ettlingen, Germany) equipped with a mini imaging gradient coil system (gradient strength 400 mT/m) and a ¹H transmit-receive quatrature coil with 72 mm inner diameter.

We used a localized PRESS sequence with a repetition time of 1.8 s and a series of different TE (TE = 12 – 50 ms) to calculate T2. We determined T2 for 9 different peaks (in the range from 0.9 – 5.35 ppm) by fitting the monoexponential model function M_TE to the measured signal intensities at the different TE.

As results we got values for the spin-spin relaxation times T2 in the range from 24.7 ms to 57.4 ms. These values result in correction factors M₀/M_TE in the range from 2.25 to 1.42 for the 9 different peak integrals arising in lipid spectra derived with localized PRESS spectroscopy with TE = 20 ms.

We have measured 9 different T2-relaxation times of the protons of lipids in rats in vivo. These values have been used to correct localized PRESS spectra measured in vivo to obtain the true values for saturation and unsaturation of the fatty acids of AT deposits in experimental animal models. Prospectively, this method is also applicable in human studies using clinical MRS.

There is increasing interest in targeting peptide receptors and their ligands for tumor diagnostics and therapy since there is evidence that some of these receptors are overexpressed in tumors compared to normal tissues. Among these receptors playing a key role in tumor progression is the neurotensin receptor (NTR) family. The present study investigated both mRNA and protein expression of NTR in human adeno- (HT-29) and squamous (FaDu) cell carcinoma cell lines and in corresponding mouse xenograft models. mRNA analysis revealed a higher expression of NTR3 compared to NTR1 and NTR2. Protein analysis revealed enhanced signals for NTR1 followed by NTR2 both in tumor cells and xenografts. In contrast, no NTR3 protein expression was detected. Autoradiography with [³H]neurotensin showed higher receptor binding activity on HT-29 compared to FaDu.

Ziel/Aim:

Spiegelbildliche Oligonukleotide sind chemisch synthetisierte Desoxyribonukleinsäuren bzw. Ribonukleinsäuren, mit einer nicht natürlich vorkommenden L-Konfiguration der Ribose. Diese Modifizierung der Nukleinsäurestruktur führt zu einer besonders hohen Stabilität gegenüber dem enzymatischen Abbau in biologischen Medien (1). Zur Markierung von L Oligonukleotiden mit dem Positronen emittierenden Radiometall Y-86-Yttrium (t1/2 = 14,7 h) muss das Molekül mit einem Chelator funktionalisiert sein. Der Einfluss unterschiedlicher Y-86-Chelatstrukturen auf die pharmakologischen Eigenschaften von Y-86-Chelat-L Nukleinsäuren wurde am Beispiel eines L RNA 12mers 1 (Sequenz: 5’ Aminohexyl UGA CUG ACU GAC-3’, MW 3975) untersucht. Dazu wurde die L RNA 1 über zwei verschiedene Chelatoren mit 86Y(III) radiomarkiert und die Bioverteilung in Ratten untersucht.

Methodik/Methods:

Die Modifizierung des L RNA 12mers 1 mit DOTA erfolgte zum einen über einen reaktiven N Succinimidylester 2 – zu DOTA L RNA 3, zum anderen über ein Isothiocyanatderivat 4 zu DOTA bz L RNA 5. Die über eine Amidbindung 3 und eine Thioharnstoffbindung 5 DOTA-modifizierten L RNAs wurden anschließend mit Y-86 in radiochemischen Ausbeuten von 76 % bzw. 85 % radiomarkiert (2). Die Identität der Verbindungen 3a und 5a wurde mit geträgerten Y-86/Y-Markierungen und Massenspektrometrie nachgewiesen (3a m/z: 4447,0 [M+H]+; 5a m/z: 4611,3 [M+H]+). Die Bioverteilungsstudien wurden für jede Verbindung mit acht männlichen Wistar Ratten durchgeführt (3a: 240 ± 15 g Gewicht; 5a: 150 ± 7.5 g Gewicht).

Ergebnisse/Results:

Die Untersuchung der Bioverteilung der beiden Y-86-markierten L RNAs 3a und 5a zeigte für beide Substanzen eine hohe renale Ausscheidung, wobei aber eine unterschiedliche Retention der radiomarkierten Verbindungen in Nieren und Nebennieren beobachtet wurde. Der Standardized uptake value (SUV) ereichte für 3a in den Nieren einen Wert von 10 ± 2,0 nach 5 min und 6,1 ± 0,53 nach 60 min. Für die Verbindung 5a stieg der SUV in den Nieren von 13 ± 1,6 nach 5 min auf 14 ± 1,1 nach 60 min. Bemerkenswert hohe SUVs (3,5 ± 0,48 und 3,2 ± 0,33) wurden in den Nebennieren nach 60 min für beide Verbindungen beobachtet. Der SUV anderer Organe lag in dieser Untersuchung für 3a und 5a nach 60 min unter 1,0. Nach 12 h Inkubation in Rattenblut bei 37 °C konnte keine Zersetzung von 5a über HPLC-Analyse beobachtet werden.

Schlussfolgerungen/Conclusions:

Die unterschiedliche chemische Anbindung der Y-86-DOTA Chelate an die L-RNA 1 deutet neben den strukturellen Unterschieden der Y-86-Komplexe in 3a und 5a auf eine starke Beeinflussung der Bioverteilung des L Oligonukleotides hin. Die hohe metabolische Stabilität der L RNA verdeutlicht das Potential von L Oligonukleotiden als molekulare Sonden für die PET.

Literatur/References:

(1) Nat Biotechnol 14 (1996), 1112-5
(2) LDDD 3(5) (2006), 330-5

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There is evidence that intrauterine growth restriction (IUGR) is associated with altered dopaminergic function in the immature brain. Compelling evidence exists that in the newborn brain, specific structures are especially vulnerable to O₂ deprivation. The dopaminergic system is shown to be sensitive to O₂ deprivation in the immature brain. However, the respective enzyme activities have not been measured in the living neonatal brain after IUGR under hypercapnic hypoxia (H/H). Therefore, ¹⁸F-labeled 6-fluoro-L-3,4-dihydroxyphenylalanine (FDOPA) together with positron emission tomography was used to estimate the aromatic amino acid decarboxylase activity of the brain of seven normal weight (body weight 2078 +/- 434g) and seven IUGR newborn piglets (body weight 893 +/- 109 g). Two positron emission tomography scans were performed in each piglet. All animals underwent a period of normoxia and moderate H/H. Simultaneously, cerebral blood flow was measured with colored microspheres and cerebral metabolic rate of O₂ was determined. In newborn normal-weight piglets, the rate constant for FDOPA decarboxylation was markedly increased in mesostriatal regions during H/H, whereas brain oxidative metabolism remained unaltered. In contrast, moderate H/H induced in IUGR piglets a marked reduction of clearance rates for FDOPA metabolites (p < 0.05), which was accompanied by a tendency of lowering the rate constant for FDOPA conversion. Furthermore, IUGR piglets maintained cerebral O₂ uptake in the early period of H/H, but during the late period of H/H, a significantly reduced cerebral metabolic rate of O₂ occurred (p < 0.05). Thus, IUGR is accompanied by a missing activation of dopaminergic activity and attenuated brain oxidative metabolism during moderate H/H. This may indicate endogenous brain protection against O₂ deprivation.

Emerging experimental data indicate that the pulmonary blood flow remained directed toward the dorsal regions after turning animals from a supine to a prone position. This finding supported the hypothesis that the distribution of perfusion throughout the lung was not primarily dictated by the gravity but by the fractal behavior of the pulmonary vasculature. However there are only limited data about the spatial distribution of lung perfusion in rats in prone and supine position. The purpose of the study was to quantify the relative perfusion (Q) distribution in rat lungs in both positions using [⁶⁸Ga]Ga-DOTA-microspheres with small-animal PET, -CT, and -MRI to obtain reference data for further investigations on injured rat lungs.

Methods:

Regional pulmonary perfusion was investigated after injection of [⁶⁸Ga]Ga-DOTA-microsphers (20 micrometer diameter) of albumin in both prone and supine positions in normal breathing rats, anesthetized with desflurane. The heart rate was continuously recorded. The right femoral artery and vein were cannulated, arterial blood pressure, blood gases, and pH were measured. The microspheres were intravenously applied. Emission data were collected for 30 min. Before and after the PET measurement the animals were studied with CT to investigate the lungs and to calculate their volumes. Randomly selected animals were studied also with smallanimal MRI. The [⁶⁸Ga]-activity 3D distributions were analyzed from the coregistered volume data reconstructed with 3D OSEM MAP algorithm (resolution in the center of field of view 1.8 mm).

Results:

There were no significant differences of mean Q in the ventral and dorsal elements of normal rat lungs.

Conclusion:

The body position (prone and supine) of normal breathing rats does not influence the mean Q btained with small-animal PET and the lung volumes measured with small-animal CT. The histogram of the regional blood flow in supine position reflects a more heterogeneous blood flow distribution.

[¹⁸F]Fluoroacetate ([¹⁸F]FAC) is discussed as an addition to the well-established PET radiotracer [¹¹C]acetate ([¹¹C]ACE) for the diagnosis and treatment monitoring of low [¹⁸F]FDG accumulating cancer entities. The purpose of this study was to establish a reproducible method of [¹⁸F]FAC synthesis, and to assess the biodistribution and kinetics in rats and tumor bearing mice to evaluate the potential of [¹⁸F]FAC for tumor imaging, and to gain information about the [¹⁸F]FAC accumulation mechanism in human squamous cell carcinoma (FaDu) and adenocarcinoma (HT-29) xenografts.

Results and Discussion:

The optimized radiosynthesis of n.c.a. sodium [¹⁸F]FAC was performed in two steps: (1) Incorporation of fluorine into (methanesulfonyloxy)-acetic acid tert.-butyl ester as the superior labeling precursor in acetonitrile followed by (2) acidic hydrolysis of the resulting [¹⁸F]fluoroacetic acid tert.-butyl ester to afford [¹⁸F]FAC. Several consecutive purification gave sodium [¹⁸F]FAC in very reproducible radiochemical yields in high radiochemical purity (>95%) within 50 min. Arterial blood samples were analyzed and no metabolites of [¹⁸F]FAC were observed up to 60 min p.i. [¹⁸F]FAC was readily accumulated in FaDu and HT-29 tumors (tumor/muscle 1.8+/-0.2 mean+/-SEM, n=6) as shown in small-animal PET studies. [¹⁸F]FAC and [¹¹C]ACE could clearly delineate the tumors and reached a tumor to muscle ratio up to two. Both agents showed a similar biodistribution. The differences were limited to the higher activity accumulation of the [¹¹C]ACE in pancreas, spleen, kidneys, and the slower blood clearance of [¹⁸F]FAC. In some animals dehalogenation was observed.

Conclusion:

The remotely-controlled two step/one pot synthesis of [¹⁸F]FAC represents a robust and reproducible procedure. The differences of biodistribution between [¹⁸F]FAC and [¹¹C]ACE in rats and tumor bearing mice are relatively small. The absence of metabolites in the arterial blood plasma allows using the plasma activity for quantitative kinetic studies without further metabolite analyses.
(Partly supported by the EU project BioCare No. 505785)

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Dedicated small-animal tomographs are nowadays available for the three major modalities PET, MRI, and CT. Utilization of all three techniques for true multimodality imaging requires the solution of several technical problems including reproducible animal positioning, overcoming file format incompatibilities and coregistration of the different image volumes, preferably without application of markers.
Methods: We developed an isolation chamber and adapter for imaging devices, enabling physiologic animal control, reproducible positioning, pathogen barrier, anesthesia, probe application and the use of catheter systems. Furthermore, we developed the necessary software for file format conversions and coregistration of the image volumes.
The basis is the animal holder system, consisting of the fixing adapters and the animal chamber that could be positioned in our three tomographs (microPET P4, SkyScan 1178, and BioScan 70/30 USR).
The animal holder system is temperature-controled. It allows gas anesthesia of the animals and could be used as a closed system. The bed is air heated.
In the different modalities the data are stored in different formats using different image matrix and pixel sizes. In order to analyze the data they are converted to a common data format (Siemens ECAT7) and the pixel sizes are adjusted. Residual differences in the relative positioning of the animals are corrected via coregistration. We implemented a mutual information algorithm using the conjugate gradient maximization method.
Validation studies showed a good coregistration of the images from PET, CT, and MRI. In longitudinal [18F]FDG studies the coregistration allowed to compare the tumor SUVmax data between different studies.
Conclusion: Multimodality imaging of small animal PET, -CT, and MRI allows the direct comparison and quantification of regional PET, CT, and MRI/MRS parameters enabling the characterization of functional and anatomical changes during tumor development and therapy.
The project was partly supported by the EU project BioCare No. 505785.

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Dendritische Liganden eröffnen einen neuen Zugang zu Radiometallpharmaka und zwar insbesondere dann, wenn es gelingt, radioaktive Metallnuklide im Kern topologisch so zu verkapseln, dass sie unter physiologischen Bedingungen kinetisch und thermodynamisch stabil fixiert sind. Eine Modifizierung der Dendrimeroberfläche erlaubt dann die Einstellung definierter Löslichkeits- und selektiver Bindungseigenschaften.
Wir berichten über die Synthese von sternförmigen Liganden mit peripheren Peptideinheiten sowie einem metallbindenden Zentrum. Als Peptid wird das biologisch aktive Neurotensinfragment NT-(8-13) eingeführt.[1] Dieses bindet an den Neurotensin-Rezeptor 1 (NTR-1), der insbesondere an duktalen exokrinen Pankreaskarzinomen stark überexprimiert ist.[2] Als Kernbaustein wird Cyclam (1,4,8,11-Tetraazacyclotetradecan) ausgewählt, das zur stabilen Bindung von diagnostisch und therapeutisch relevanten Radiometallnukliden, wie 64/67Cu, 99mTc und 186/188Re, geeignet ist. Derartige radioaktiv markierte Peptidkonjugate können Bedeutung in der Tumordiagnostik und Tumortherapie erlangen.
Es werden Ligand-Rezeptor-Bindungs-studien an NTR-1-überexprimierenden humanen Adenokarzinom(HT-29)-Zellen präsentiert. Erste Ergebnisse weisen auf eine sehr hohe Affinität des Tetramers I sowie des entsprechenden Kupfer(II)-Komplexes zum Neurotensin-Rezeptor 1 im pico-molaren Bereich hin und ist damit vergleichbar zu einem Tetramer anderer Struktur {3]. Es werden sich Untersuchungen zur Markierung mit 64Cu anschließen, um Aussagen zur metabolischen Stabilität dieses Liganden sowie zur Bioverteilung in vivo zu erhalten.

[1] B.M. Tyler-McMahon et al., Regul. Pept. 2000, 93, 125-136
[2] J. C. Reubi, Endocr. Rev. 2003, 24, 389-427.
[3] C. Hultsch et al., Bioorg. Med. Chem. 2006, 14, 5913-5920

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The reactive gas incorporation into a Ti sputter target has been investigated using laterally resolving ion beam analysis during DC magnetron deposition of TiN in an Ar/N2 atmosphere. At sufficiently low reactive gas flow, the nitrogen incorporation exhibits a pronounced lateral variation, with a lower areal density in the target race track compared to the target centre and edge. The findings are reproduced by model calculations. In the race track, the balance of reactive gas injection and sputter erosion is shifted towards erosion. The injection of nitrogen is dominated by combined molecular adsorption and recoil implantation versus direct ion implantation.

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Hypoxia causes upregulation of vascular endothelial growth factor (VEGF) which is a key regulator in tumor angiogenesis and essential for the proliferation of endothelial cells. Endothelial cells have been described to accumulate radiotracers like ¹⁸F-FDG. However, the contribution of radiotracer uptake by endothelial cells to uptake measured in tumors by positron emission tomography (PET) is still unclear. In this study ¹⁸F-FDG and ¹⁸F-FMISO radiotracer uptake in various tumor and primary endothelial cells cultured at hypoxic conditions was investigated. Experimental hypoxia was confirmed by significant upregulation of VEGF mRNA. In comparison to normoxic conditions, cellular uptake of ¹⁸F-FDG was significantly increased at hypoxic conditions in two of the tumor and all endothelial cells, whereas ¹⁸F-FMISO uptake was only enhanced in tumor cell lines HT-29 and MCF-7. Our data showed a marked influence of experimental hypoxia on the metabolism and gene expression of tumor and endothelial cells in vitro. This indicates an important contribution of endothelial cells to ¹⁸F-FDG radiotracer uptake in tumors and for the visualization of tumors by means of PET.

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Mass-shift of the ρ and ω meson and their mixing in nuclear matter

Tantalum oxide was deposited by radical enhanced atomic layer deposition using tantalum ethoxide and oxygen radicals. The radicals were produced by dissociating oxygen gas in a remote microwave plasma discharge. Argon was used as the carrier and purge gas. The films were deposited at 150 and 250°C on glass, silicon, and platinum substrates. Growth rate of the films was 0.19 nm per cycle with a 0.6 s pulse length for tantalum ethoxide and 3 s for oxygen radicals. The films were amorphous according to X-ray diffraction. The densities measured by X-ray reflectivity were between 7.1 and 7.6 g/cm3 for films grown both at 150 and 250°C. The dielectric constants were 28 and 36 for films grown on platinum electrodes at 150 and 250 °C, respectively. The leakage current densities at 1 MV/cm electric field were less than 1 x 10-8 A/cm2 for both deposition temperatures. The effect of water as an additional oxidant was studied at 250 °C. The water was supplied as a separate pulse either right before or after the tantalum ethoxide pulse.

We report the structural and tribological characterization of nanostructured CNx thin films produced by the deposition of a supersonic carbon cluster beam assisted by nitrogen ion bombardment. The influence of the deposition parameters on the chemical composition and structure of the films has been systematically studied by X-ray photoelectron spectroscopy, elastic recoil detection analysis, transmission electron microscopy and atomic force microscopy. Depending on the deposition parameters, the films show a structure ranging from amorphous to disordered graphitic with interlinked planes. Nitrogen content depends on the nitrogen ion kinetic energy. The films have a very low density with a high surface roughness. Friction measurements at the nanoscale show a correlation between nitrogen content and mechanical properties of the system.

A new approach for the modelling of poly-dispersed bubbly flows – the so-called Inhomogeneous Multi Bubble Size Group (MUSIG) model was developed jointly by FZD and ANSYS. It was implemented into the CFX code and is now available starting with code version 10. This model enables the consideration of a number bubble classes in the mass balance as well as in the momentum balance. Usually only few classes are required for the momentum balance to reflect the bubble size dependent de-mixing of small and large bubbles caused by the inversion of the sign of the lift force with increasing bubble diameter. The model was developed and first tested using data for vertical pipe flow. To show the indepen¬dency of the model on geometry and to test it for more complex flow situations, now experiments were conducted with a pronounced three-dimensional character of the flow fields. A diaphragm which blocks about one half of the pipe was placed into the vertical DN200 test sections available at the TOPFLOW facility of FZD. Main feature is the trans¬location of the diaphragm to scan the 3D void field with a stationary wire-mesh sensor. Be¬sides the measurement of time-averaged void fraction fields, a novel data evaluation method was developed to extract estimated liquid velocity profiles from the wire-mesh sensor data. Simulations were done using CFX-10 and applying the Inhomogeneous MUSIG model. In general the complex flow including a recirculation zone behind the obstacle (where bubble coalescence is observed) and a pronounced jet of high liquid velocity at the unobstructed side (were bubble break-up dominates) are reflected well in the simulations. There is a strong interaction between size dependent bubble migration in the complex liquid velocity field (mainly caused by the lift force) and local bubble coalescence and break-up. The data clearly demonstrate the necessity to consider the bubble size dependent bubble migration for an adequate simulation of bubbly flows in complex geometries. Some weaknesses of the simulations are connected with shortcomings in the modelling of bubble coalescence and break-up.

The role of the lift force for the stability of bubbly flows is discussed. The main interest is directed towards bubble columns, since instabilities caused by the lift force may be one important reason for the transition from homogeneous to heterogeneous flow regimes. The lift force acts on rising bubbles in lateral direction, when gradients of the liquid velocity are present. Such gradients may result from the main liquid flow or from local disturbances in case of initially homogeneous flows. Depending on the sign of the lift force such local disturbances in a homogeneous flow may be damped or enhanced. The corresponding feedback mechanism was previously analysed by means of a linear stability analyses. In the result criteria for stability were obtained for mono-dispersed flow, for a flow with two bubble size groups and finally with some additional approximations also for the case of N bubble size groups or a given bubble size distribution. Recently two different groups confirmed the stability criteria experimentally. Now the effects were investigated also by means of CFD simulations. In a first step bubble coalescence was excluded, while the second step comprises a numerical study which includes coalescence. In the latter case coalescence leads to a transition from stable to instable flow patterns along the height position in the column. The transitions fit well together with the criteria for stability. Finally the influence of the lift force is discussed also for other flow situations.

High-spin states in Rh-105 were populated by the Zr-96(C-13,p3n) reaction at beam energies of 51 and 58 MeV, and studied using the EUROBALL IV gamma-ray spectrometer and the DIAMANT charged particle array. A pair of nearly degenerate DeltaI = 1 three-quasiparticle bands with the same spins and parity have been observed. Comparison of the experimental results with tilted axis cranking calculations confirms the chiral character of the two bands, while arguments based on the excitation of particles within the pig(9/2)nu(h(11/2))(2) configuration of the yrast band and comparison with the previously observed gamma band exclude the other possible interpretations. This is the first experimental evidence for three-quasiparticle chiral structure in the A similar to 100 region, and the first simultaneous observation of a gamma band and chiral partner bands in one nucleus. (C) 2004 Elsevier B.V. All rights reserved.

Recently, Davids and Typel recommended a "low" value of S-17(0) based on fits to published direct and Coulomb dissociation data, in which they excluded the precise result of Junghans We show that their statistical analysis is incorrect due to a substantial underestimate of the experimental uncertainties, and that there is no reason to exclude the Junghans result based on statistical arguments.

The Rh-105 nucleus has been studied by in-beam gamma spectroscopy with the heavy-ion fusion-evaporation reaction Mo-100(B-11, alpha2ngamma) at 43 MeV A rich variety of structures was observed at high and low spin, using gamma - gamma - t and gamma - gamma - particle coincidences and directional correlation ratios. Four magnetic dipole bands have also been observed at high spin. Two of them are nearly degenerate in excitation energy and could be chiral partners, as predicted by Tilted Axis Cranking calculations.

The Rh-105 nucleus has been studied with the Mo-100(B-11, alpha2ngamma) reaction at 43 MeV incident energy. A rich variety of structures was observed at high and low spins, using gamma-gamma-t and gamma-gamma-particle coincidences and directional correlation ratios. A gamma-vibrational band was observed for the first time in this nucleus. A new structure based on the intruder 1/2(+)[431] proton orbital was identified. Four magnetic dipole bands have also been observed at high spin, three of which have negative parity and have similar characteristics: they are very regular in energy spacing, presenting nearly constant alignments and large values of B(M1)/B(E2) ratios. Two of them are nearly degenerate in excitation energy and could be chiral partners. The pig(9/2)xnuh(11/2)(g(7/2),d(5/2)) configuration is tentatively assigned for these bands, with the angular momenta of the proton and neutron intruders and the collective angular momentum aligning along the three perpendicular axes of the triaxial core, as predicted by tilted axis cranking calculations.

Wall parallel Lorentz forces have been used to excite the separated flow on the suction side of inclined symmetric hydrofoils. Resulting lift enhancements resemble those known from alternative active flow control methods. The controlled flow is characterized by a small number of relatively large vortices, which are related to the control mechanism. Consequently, time resolved flow fields have been analyzed by proper orthogonal decomposition and continuous wavelet transform to extract dominant features. Both evaluation methods highlight significant influences of excitation frequency, wave form, and amplitude.

Combined measurements of charge trapping and electroluminescence intensity as a function of injected charge and current have been carried out with the aim of clarifying the mechanisms of electroluminescence (EL) quenching in Ge-implanted ITO-SiO2-Si light-emitting silicon diodes. Good correlation between the negative charge capture in traps of small effective capture cross-sections (sigmat1 e=1.7x10-19 cm2 and sigmat2 e=4.8x10-20 cm2) located in SiO2, and the quenching of the asymmetrical EL line with a maximum intensity at 400 nm has been observed. Similar correlation between the electron capture in traps with extremely small effective capture cross-section (sigmat3 e=5x10-21 cm2) and the quenching of the EL line at 637 nm has been established. A quantitative model for the EL quenching has been developed, which takes into account the modification of the luminescent centers with subsequent electron capture at the newly generated trap! s. The model shows good agreement between simulation and experimental data. It also demonstrates that small effective capture cross-sections for electron charging during the EL quenching are determined by the probability of the luminescence centers (LCs) being disrupted, and enables one to estimate the Ge concentration associated with the EL at 400 nm.

Study on the discretization effects in HELIOS 1.9 on teh basis of a single cell calculation