Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions

The Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MSL-CETSOL and MICAST) are two investigations which supports research into metallurgical solidification, semiconductor crystal growth (Bridgman and zone melting), and measurement of thermo-physical properties of materials. This is a cooperative investigation with the European Space Agency (ESA) and National Aeronautics and Space Administration (NASA) for accommodation and operation aboard the International Space Station (ISS). Research Summary: Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing (CETSOL) and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MICAST) are two complementary investigations which will examine different growth patterns and evolution of microstructures during crystallization of metallic alloys in microgravity. The aim of these experiments is to deepen the quantitative understanding of the physical principles that govern solidification processes in cast alloys by directional solidification

The strong-coupling limit of lattice Landau gauge

We report on our recent study of the gluon and ghost propagators of pure SU(2) minimal lattice Landau gauge in the strong-coupling limit. In this limit, we find evidence of the conformal infrared behaviour of these propagators as predicted by functional continuum methods. However, in the strong-coupling limit this happens for lattice momenta with a^2q^2>1, in units of the lattice spacing a. Deviations from conformal scaling for a^2q^2<1 are well parameterised by a transverse gluon mass. A comparison of various lattice definitions of gauge potentials, all equivalent in the continuum limit, shows that (a) both the critical exponent and coupling can be extracted unambiguously from the high-momentum data in the strong-coupling limit, in good agreement with the continuum predictions; but that on the other hand (b) the massive branch depends on the definition of lattice gluon fields and is thus not unambiguously defined. We demonstrate that this ambiguity is also present in the low-momentum region for commonly used values of the lattice coupling in SU(2).Comment: 5 pages, talk presented at the 8th Conference Quark Confinement and the Hadron Spectrum, September 1-6, 2008, Mainz, German

In vitro analyses of mitochondrial ATP/phosphate carriers from Arabidopsis thaliana revealed unexpected Ca2+-effects

Background: Adenine nucleotide/phosphate carriers (APCs) from mammals and yeast are commonly known to adapt the mitochondrial adenine nucleotide pool in accordance to cellular demands. They catalyze adenine nucleotide - particularly ATP-Mg - and phosphate exchange and their activity is regulated by calcium. Our current knowledge about corresponding proteins from plants is comparably limited. Recently, the three putative APCs from Arabidopsis thaliana were shown to restore the specific growth phenotype of APC yeast loss-of-function mutants and to interact with calcium via their N-terminal EF-hand motifs in vitro. In this study, we performed biochemical characterization of all three APC isoforms from A. thaliana to gain further insights into their functional properties. Results: Recombinant plant APCs were functionally reconstituted into liposomes and their biochemical characteristics were determined by transport measurements using radiolabeled substrates. All three plant APCs were capable of ATP, ADP and phosphate exchange, however, high preference for ATP-Mg, as shown for orthologous carriers, was not detectable. By contrast, the obtained data suggest that in the liposomal system the plant APCs rather favor ATP-Ca as substrate. Moreover, investigation of a representative mutant APC protein revealed that the observed calcium effects on ATP transport did not primarily/essentially involve Ca2+-binding to the EF-hand motifs in the N-terminal domain of the carrier. Conclusion: Biochemical characteristics suggest that plant APCs can mediate net transport of adenine nucleotides and hence, like their pendants from animals and yeast, might be involved in the alteration of the mitochondrial adenine nucleotide pool. Although, ATP-Ca was identified as an apparent import substrate of plant APCs in vitro it is arguable whether ATP-Ca formation and thus the corresponding transport can take place in vivo

An optimal stratified Simon two-stage design

In Phase II oncology trials, therapies are increasingly being evaluated for their effectiveness in specific populations of interest. Such targeted trials require designs that allow for stratification based on the participants’ molecular characterisation. A targeted design proposed by Jones and Holmgren (JH) Jones CL, Holmgren E: ‘An adaptive Simon two-stage design for phase 2 studies of targeted therapies’, Contemporary Clinical Trials 28 (2007) 654-661.determines whether a drug only has activity in a disease sub-population or in the wider disease population. Their adaptive design uses results from a single interim analysis to decide whether to enrich the study population with a subgroup or not; it is based on two parallel Simon two-stage designs. We study the JH design in detail and extend it by providing a few alternative ways to control the familywise error rate, in the weak sense as well as the strong sense. We also introduce a novel optimal design by minimising the expected sample size. Our extended design contributes to the much needed framework for conducting Phase II trials in stratified medicine

Certification of the Specific Micropore Volume and the Median Micropore Width of Two Microporous Reference Materials According to Draft-DIN 66135-4, BCR-704, BCR-705.

Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel

Preconditioning Maximal Center Gauge with Stout Link Smearing in SU(3)

Center vortices are studied in SU(3) gauge theory using Maximal Center Gauge (MCG) fixing. Stout link smearing and over-improved stout link smearing are used to construct a preconditioning gauge field transformation, applied to the original gauge field before fixing to MCG. We find that preconditioning successfully achieves higher gauge fixing maxima. We observe a reduction in the number of identified vortices when preconditioning is used, and also a reduction in the vortex-only string tension.Comment: 9 pages, 4 figure

Flipped Classroom in der Wirtschaftsinformatik

Die Technische Universität Chemnitz und Technische Universität Bergakademie Freiberg führten im Rahmen des LiT-Projekts „FC WInf – Flipped Classroom in der Wirtschaftsinformatik“ ein kooperatives Lernprojekt im Sommersemester 2014 und Wintersemester 2014/2015 durch. Ziel war es, durch die Implementierung von Online-Lerneinheiten die individuelle Selbstlernphase der Studierenden zu stärken. Der Beitrag fasst die Konzeption und Durchführung zusammen und präsentiert wesentliche Ergebnisse der Evaluation

Shedding light on silica biomineralization by comparative analysis of the silica‐associated proteomes from three diatom species

Morphogenesis of the intricate patterns of diatom silica cell walls is a protein-guided process, yet to date only very few such silica biomineralization proteins have been identified. Therefore, it is currently unknown whether all diatoms share conserved proteins of a basal silica forming machinery, and whether unique proteins are responsible for the morphogenesis of species-specific silica patterns. To answer these questions, we extracted proteins from the silica of three diatom species (Thalassiosira pseudonana, Thalassiosira oceanica, and Cyclotella cryptica) by complete demineralization of the cell walls. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis of the extracts identified 92 proteins that we name ‘soluble silicome proteins’ (SSPs). Surprisingly, no SSPs are common to all three species, and most SSPs showed very low similarity to one another in sequence alignments. In-depth bioinformatics analyses revealed that SSPs could be grouped into distinct classes based on short unconventional sequence motifs whose functions are yet unknown. The results from the in vivo localization of selected SSPs indicates that proteins, which lack sequence homology but share unconventional sequence motifs may exert similar functions in the morphogenesis of the diatom silica cell wall

Fabrication and characterization of SiO2 glass containing YbPO4 crystals

In the present work, we report on the preparation of silicate glass containing crystals by means of melting a mixture of YbPO4 xenotime structured crystals and SiO2 nanoparticles. This nanoparticle mixture is used for preparation of large volume core preforms for laser active optical fiber. Temperature dependent sintering and fiber drawing experiments at temperatures up to about 2000 °C were conducted in order to assess the integrity of the crystals in the preform and fiber, respectively. The survival of YbPO4 crystalline particles in silica was investigated by X-ray diffraction (XRD), electron probe microanalysis (EPMA), Raman spectroscopy as well as static and time resolved fluorescence measurements. It was found that the particles withstand the high-temperature steps during the fiber fabrication process. XRD and spectroscopic measurements suggest that the Yb ions are located in a crystalline but also in an amorphous silica-dominated surrounding in the fiber, suggesting the partial decomposition of the crystals during the fiber fabrication.Peer reviewe