Degenerate Quantum Gases in Microgravity

Clouds of ultra-cold atoms and especially Bose–Einstein condensates (BEC) provide a source for coherent matter-waves in numerous earth bound experiments. Analogous to optical interferometry, matter-wave interferometers can be used for precision measurements allowing for a sensitivity orders of magnitude above their optical counterparts. However, in some respects the presence of gravitational forces in the lab limits experimental possibilities. In this article, we report about a compact and robust experiment generating Bose–Einstein condensates in the drop tower facility in Bremen, Germany. We also present the progress of building the succeeding experiment in which a two species atom interferometer will be implemented to test the weak equivalence principle with quantum matter.     

Influence of additives on interfacial phenomena during film formation of powder coatings

Film formation of powder coatings is illuminated from a physico-chemical point of view. Significant parameters influencing the film formation of powder coatings are surface (wetting) tension and viscosity of the polymer melt formed during the film formation process. A newly developed measuring device for the investigation of wetting at elevated temperatures is presented. This device allows systematic investigations of the temperature dependence of the wetting tension of powder coating binder systems. By combining analytical and surface tension measurements, it is possible to gain new information about the mechanism of action of additives in these melts. Hohe Stra?e 6, D-01069 Dresden, Germany.     

Discontinuous Galerkin solution of a phase-field model in isothermal chemical vapor infiltration of SiC

The microstructure evolution of the isothermal chemical vapor infiltration (ICVI) of silicon carbide (SiC) from methyltrichlorosilane (MTS) is simulated by a phase-field model which is implemented numerically using the discontinuous Galerkin method. The model consists of a phase-field equation describing the diffusive interface kinetics and a species transport equation describing the mass balance. For the diffusive interface kinetics, a new form of the free energy density related to the ICVI process is adopted to ensure two stable states of gas phase and solid phase, and the Gibbs free energy changing between these two phases is taken as driving force. For the mass balance, two process intensities depending on the phase-field parameter are introduced to account for the homogeneous gas reaction and the heterogeneous surface reaction including the influence of the by-product hydrogen chloride (HCl). Finally, a discontinuous Galerkin formulation is derived for the nonlinear phase-field model and a priori error analysis is used for the semi-discontinuous formulations based on the proof of the uniqueness of the solution of the discontinuous approximation. Two numerical examples are presented to demonstrate the validity of the discontinuous Galerkin method and to investigate the effect of geometric parameters on microstructure evolution.     

AHAPS-functionalized silica nanoparticles do not modulate allergic contact dermatitis in mice

Allergic contact dermatitis (ACD) is a common skin disease in people and may become a potential site of exposure to nanoparticles (NP). Silica nanoparticles (SiO₂-NP) possess a promising potential for various medical and non-medical applications, including normal and diseased skin as target organs. However, it has been shown that negatively charged SiO₂-NP may act as proinflammatory adjuvant in allergic diseases. The effect of topical SiO₂-NP exposure on preexisting ACD has not been studied to date although this reflects a common in vivo situation. Of particular interest are the potential effects of positively charged N-(6-aminohexyl)-aminopropyltrimethoxysilane (AHAPS)-functionalized SiO₂-NP which are promising candidates for delivery systems, including gene delivery into the skin. Here, the effects of such AHAPS-functionalized SiO₂-NP (55 ± 6 nm in diameter) were studied in an oxazolone-induced ACD model in SKH1 mice and compared to ACD mice treated with vehicle only. The clinical course of the disease was assessed by monitoring of the transepidermal water loss (TEWL) and the erythema. In histologic and morphometric analyses, the distribution of particles, the degree of inflammation, epidermal thickness, and the inflammatory infiltrate were characterized and quantified by standard and special histological stains as well as immunohistochemistry for CD3+ lymphocytes. To assess possible systemic effects, serum immunoglobulin E (IgE) was determined by enzyme-linked immunosorbent assay. Following administration of AHAPS-SiO₂-NP for five consecutive days, no effects were observed in all clinical, histologic, morphometric, and molecular parameters investigated. In conclusion, positively charged AHAPS-SiO₂-NP seem not to affect the course of ACD during exposure for 5 days.     

Thermal issues in machine tools

This paper presents a review of the latest research activities and gives an overview of the state of the art in understanding changes in machine tool performance due to changes in thermal conditions (thermal errors of machine tools). The topics are focused on metal cutting machine tools, especially on turning and milling machines as well as machining centres. The topics of the paper thermal issues in machine tools include measurement of temperatures and displacements, especially displacements at the tool centre point, computations of thermal errors of machine tools, and reduction of thermal errors. Computing the thermal errors of machine tools include both, temperature distribution and displacements. Shortly addressed is also to avoid thermal errors with temperature control, the influence of fluids and a short link to energy efficiency of machine tools. The paper presents the summary of research work in the past and current. Research challenges in order to achieve a thermal stable machine tool are discussed. The paper apprehend itself as an update and not a substitution of two published keynote papers of Bryan et al. [28] in 1990 and Weck et al. [199] in 1995.     

Development of a TES-Based Anti-coincidence Detector for Future x-Ray Observatories

Microcalorimeters onboard future x-ray observatories require an anti-coincidence detector to remove environmental backgrounds. In order to most effectively integrate this anti-coincidence detector with the main microcalorimeter array, both instruments should use similar read-out technology. The detectors used in the Cryogenic Dark Matter Search (CDMS) use a phonon measurement technique that is well suited for an anti-coincidence detector with a microcalorimeter array using SQUID readout. This technique works by using a transition-edge sensor (TES) connected to superconducting collection fins to measure the athermal phonon signal produced when an event occurs in the substrate crystal. Energy from the event propagates through the crystal to the superconducting collection fins, creating quasiparticles, which are then trapped as they enter the TES where they produce a signal. We are currently developing a prototype anti-coincidence detector for future x-ray missions and have recently fabricated test devices with Mo/Au TESs and Al collection fins. We present results from the first tests of these devices which indicate a proof of concept that quasiparticle trapping is occurring in these materials.     

Small Pitch Transition-Edge Sensors with Broadband High Spectral Resolution for Solar Physics

We are developing small pitch transition-edge sensor (TES) X-ray detectors optimized for solar astronomy. These devices are fabricated on thick Si substrates with embedded Cu heat-sink layer. We use 35×35?μm² Mo/Au TESs with 4.5?μm thick Au absorbers. We have tested devices with different geometric absorber stem contact areas with the TES and surrounding substrate area. This allows us to investigate the loss of athermal phonons to the substrate. Results show a correlation between the stem contact area and a broadening in the spectral line shape indicative of athermal phonon loss. When the contact area is minimized we have obtained exceptional broadband spectral resolution of 1.28±0.03?eV at an energy of 1.5?keV, 1.58±0.07?eV at 5.9?keV and 1.96±0.08?eV at 8?keV. The linearity in the measured gain scale is understood in the context of the longitudinal proximity effect from the electrical bias leads resulting in transition characteristics that are strongly dependent upon TES size.     

Der Frequenzgang des Wirkungsgrades eisengesehlossener Transformatoren

Ohne ZusammenfassungAuszug aus einer Dissertation der Technischen Hochschule München: Studien an Transformatoren unter besonderer Berücksichtigung ihres Verhaltens bei verschiedenen Frequenzen, 1934.     

Auftreten von Pflanzenschutzmitteln in Oberflächengewässern und im Grundwasser

An overview of the current situation of pesticide occurrence in water is presented using data from the EU-contries Denmark, England, France, Germany, and the Netherlands. Data were extracted from official reports. The data base is rather heterogenous, as the monitoring strategies vary in a wide range depending on the administrative responsibilities. In the publications, water pollution with pesticides is evaluated using the drinking water standard values for single substances (0,1 μg/l), a toxicological evaluation is missing. In surface waters, substances with regionally high sell numbers or high application amounts dominate. They belong to the chemical groups triacines, phenoxy carbolic acids and urea derivates. Talking about groundwater, the time scale has to be considered as well, as the geological system reacts as a buffer. Here, the triacines and their metabolits dominate having been applicated for tens of years in high amounts. Different measures to obtain a longterm water protection are discussed.     

Oxygen Processing of Hg and Tl Based Cuprate Superconductors

The effect that oxygen stoichiometry has on the physical properties of high critical temperature superconductors is well documented. For a general understanding of the conditions necessary for processing high critical temperature superconducting materials, phase equilibrium diagrams have been quite useful; however, such diagrams provide no information concerning the time required to oxygenate superconducting structures. In this paper, we present experimental results that clearly demonstrate the relationships among phase equilibrium diagrams, oxygen diffusion coefficients and grain sizes with the time required to adequately oxygenate high critical temperature superconducting materials and device structures. While oxygen processing of the high critical temperature superconductor, YBa₂Cu₃O_7–, is emphasized throughout this paper, the concepts and relationships discussed herein, in general, can be applied to the oxygen processing of other high critical temperature superconductors including the Hg and TI based systems.where the investigations were conducted has been transferred to the U.S. Army Research LaboratoryD.M. Pierce: Work performed while a National Research Council Associate