Reibungsversuche mit Krypton bei niedrigen Drücken

Tests of a linear Equation on the Evaluation of Krypton Friction Experiments at low Pressures and Connections to Viscosity Effects The coefficient of viskosity is nearly constant in the region with STP conditions and is independent of the pressure. This coefficient decreases with lowering the pressure until the region of molecular flow is reached. There we have free molecular‐ or vacuum viscosity. Experiments with the friction of gas have to take in the gas between surfaces which are movabel and parallel. Reactions of the gas with the moving surface cannot be neglected. We made our lab‐examinations of gas friction effects between two rotating cylinders. Generally there is a linear equation of the reciprocal values of viscosities and pressures. Our experiments show a region, where this linear relation is valid. This region has a low limit with coming to molecular flow and an upper limit if the gas is warmed up by friction at higher pressures.     

Isolation of Decidual Macrophages and Hofbauer Cells from Term Placenta—Comparison of the Expression of CD163 and CD80

(1) Background: Placental immune cells are playing a very important role in a successful placentation and the prevention of pregnancy complications. Macrophages dominate in number and relevance in the maternal and the fetal part of the placenta. The evidence on the polarization state of fetal and maternal macrophages involved in both, healthy and pregnancy-associated diseases, is limited. There is no representative isolation method for the direct comparison of maternal and fetal macrophages so far. (2) Material and Methods: For the isolation of decidual macrophages and Hofbauer cells from term placenta, fresh tissue was mechanically dissected and digested with trypsin and collagenase A. Afterwards cell enrichment was increased by a Percoll gradient. CD68 is represented as pan-macrophage marker, the surface markers CD80 and CD163 were further investigated. (3) Results: The established method revealed a high cell yield and purity of the isolated macrophages and enabled the comparison between decidual macrophages and Hofbauer cells. No significant difference was observed in the percentage of single CD163⁺ cells in the distinct macrophage populations, by using FACS and immunofluorescence staining. A slight increase of CD80⁺ cells could be found in the decidual macrophages. Considering the percentage of CD80⁺CD163⁻ and CD80⁻CD163⁺ cells we could not find differences. Interestingly we found an increased number of double positive cells (CD80⁺CD163⁺) in the decidual macrophage population in comparison to Hofbauer cells. (4) Conclusion: In this study we demonstrate that our established isolation method enables the investigation of decidual macrophages and Hofbauer cells in the placenta. It represents a promising method for direct cell comparison, enzyme independently, and unaffected by magnetic beads, to understand the functional subsets of placental macrophages and to identify therapeutic targets of pregnancy associated diseases.     

Neutron radiography study of hydrogen desorption in technical iron

The purpose of the present study is to show the feasibility of examining hydrogen desorption in technical iron samples using neutron radiography at the ANTARES facility of the FRM II research reactor, Technische Universität München. It has been shown that this method is appropriate for in situ determination of hydrogen desorption for concentrations as low as 20 ppm_H. Experiments were carried out in the temperature range from room temperature up to 260 °C. Measurement was based on direct comparison between electrochemically hydrogen-loaded iron samples and hydrogen-free reference samples at the same temperature. This enables the determination of hydrogen concentration as a function of time and temperature. Ex situ carrier gas hot extraction experiments using the same temperature?Ctime profiles as the neutron radiography experiments have been used to calibrate the greyscale values of the radiographs to defined hydrogen concentrations. It can be stated that hydrogen desorption correlates with sample temperature.     

Structural properties and electrical behaviour of thin silicon oxynitride layers

Thin SiO₂ and SiO_xN_y layers were grown on silicon using Rapid Thermal Processing (RTP) in either O₂ or N₂O ambient. Subsequent annealing or nitridation was performed in order to improve the electrical stability. The composition of the films, in particular the incorporation of nitrogen and hydrogen, has been studied. We obtained the distribution of states at the Si/insulator interface through the evaluation of CV measurements and investigated the charge trapping in the layers analysing the voltage–time behaviour during Fowler–Nordheim constant current injection. Furthermore, assuming a trap assisted tunneling mechanism, the influence of near interface trap states on the current voltage characteristic was used to derive an effective insulator state distribution.     

Reliability challenges for copper low-k dielectrics and copper diffusion barriers

The performance of interconnects containing micro- (pore size smaller than 2 nm) and meso-porous (pore size larger than 2 nm) interlevel dielectrics is influenced by material selection, integration scheme and virtually all fabrication steps. It is generally reported that the reliability margin of the dielectric/barrier/copper system is shrinking. Barrier and dielectric integrity play a most important role in line-to-line leakage and Time Dependent Dielectric Breakdown (TDDB) reliability. TDDB has never been an issue for Cu-SiO₂ interconnects, but for sub-100 nm copper/barrier/low-k systems it becomes challenging. When monitoring the integrated dielectric properties early failures can be caused by weak integration interfaces, dielectric damage during the integration, defective diffusion barrier or other non-uniformities related to the damascene process. Recent advances are reviewed along with examples and reference to state of the art.     

InGaAsSb(Gd)/InAsSbP double heterostructure lasers (λ=3.0–3.3 µm) for diode laser spectroscopy

Data on threshold currents, the differential quantum efficiency, the emission spectrum, current tuning, and radiation power of mesastripe InGaAsSb(Gd)/InAsSbP double heterostructure lasers with λ=3.0–3.3 µm and a cavity length of 70–150 µm in a temperature range of 50–107 K are reported. In the experiments, the threshold currents I _th<10 mA, a total output power of 0.5 mW/facet, and a single-mode power of 0.43 mW at 77 K in the cw regime were obtained. Lasers operated in the single-mode regime at currents I≤6I _th, the spectral purity was as high as 650: 1, the tuning rate was 210 cm^?1/A, and the tuning range was 10 cm^?1 wide. An example of methane detection at 3028.75 cm^?1 is presented.