Study of Spin-Valve Operation in Permalloy–SiO2–Silicon Nanostructures

Magnetotransport studies are performed on nanoscale Permalloy(Py)–(Mg)–SiO₂-degenerate Si(100) tunneling devices in spin-valve geometry with and without Mg interlayer. Highly remanent, single domain Py electrodes (15–100-μm length, 100–1000-nm width) are realized by electron-beam lithography, electron-beam evaporation, and subsequent lift-off. Different widths ensure subsequent switching of the Py nanoelectrodes in increasing magnetic fields. A suppression of spin-polarized current is expected for antiparallel magnetization configuration of source and drain contacts (i.e. positive magnetoresistance) if spin injection and detection have been successfully implemented. Magnetic hysteresis curves of Py nanowire arrays measured at temperatures from 5 K up to 300 K reveal increasing coercive fields (up to 40 mT) for decreased nanowire widths as required for device operation. Small positive magnetoresistance is observed for the spin-valve geometry with Mg interlayer at 4.2 K, contrary to the negative anisotropic magnetoresistance measured of single wires.     

Diffusion des Stickstoffs in flüssigen eisenreichen Mehrstofflegierungen

Darstellung der Theorien zur Berechnung von Diffusionskoeffizienten des Stickstoffs in reinem flüssigem Eisen. Aussagen über den thermodynamischen Faktor zur Bewertung des Einflusses von Legierungselementen. Angabe empirischer Ansätze zur Berechnung des Einflusses von Legierungselementen mit Hilfe von Aktivitätskoeffizienten und Gleichgewichtslöslichkeiten sowie ihre Anwendung auf Systeme mit einem oder mehreren Zusatzelementen. Hinweise auf die Notwendigkeit weiterer Versuche zur Erhärtung der Zusammenhänge auch in theoretischer Sicht.     

Einfluß verschiedener Legierungselemente auf die Größe des γ-Raumes im System Eisen-Chrom-Kohlenstoff

Zusammenwirken der beiden geschlossenen γ-Felder der Systeme Eisen–Chrom und Eisen–Vanadin in Gegenwart von Kohlenstoff. Eisenecke des Vierstoffsystems. Schnitte lei 1050 °C, 1% V, 13% Cr und 0,2% C.     

Mechanisms, models, and simulations of metal-coated fiber consolidation

Recent experimental studies of the hot isostatic consolidation of Ti-6Al-4V-coated SiC fibers contained in cylindrical canisters have revealed an unexpectedly high rate of creep densification. A creep consolidation model has been developed to analyze its origin. The initial stage of consolidation has been modeled using the results of contact analyses for perfectly plastic and power-law creeping cylinders that contain an elastic ceramic core. Final stage densification was modeled using a creep potential for a power-law material containing a dilute concentration of cusp-shaped voids with a shape factor similar to that observed in the experiments. Creep rates were microstructure sensitive and so the evolution of matrix grain size and the temperature dependence of the α/β-phase volume fractions were introduced into the model using micromechanics-based creep constitutive relationships for the matrix. To account for load shielding by the deformation resistant canister, the consolidation model was combined with an analysis of the creep collapse of a fully dense pressure vessel. The predicted densification rates were found to agree well with the experimental observations. The high densification rate observed in experiments was the result of the small initial grain size of the vapor-deposited matrix combined with retention of the cusp shape of the interfiber pores.     

Influence of structural properties on ballistic transport in nanoscale epitaxial graphene cross junctions

In this paper we investigate the influence of material and device properties on the ballistic transport in epitaxial monolayer graphene and epitaxial quasi-free-standing monolayer graphene. Our studies comprise (a)?magneto-transport in two-dimensional (2D) Hall bars, (b)?temperature- and magnetic-field-dependent bend resistance of unaligned and step-edge-aligned orthogonal cross junctions, and (c)?the influence of the lead width of the cross junctions on ballistic transport. We found that ballistic transport is highly sensitive to scattering at the step edges of the silicon carbide substrate. A suppression of the ballistic transport is observed if the lead width of the cross junction is reduced from 50?nm to 30?nm. In a 50?nm wide device prepared on quasi-free-standing graphene we observe a gradual transition from the ballistic into the diffusive transport regime if the temperature is increased from 4.2 to about 50?K, although 2D Hall bars show a temperature-independent mobility. Thus, in 1D devices additional temperature-dependent scattering mechanisms play a pivotal role.     

Blastobotrys (Arxula) adeninivorans: a promising alternative yeast for biotechnology and basic research

Blastobotrys adeninivorans (syn. Arxula adeninivorans) is a non‐conventional, non‐pathogenic, imperfect, haploid yeast, belonging to the subphylum Saccharomycotina, which has to date received comparatively little attention from researchers. It possesses unusual properties such as thermo‐ and osmotolerance, and a broad substrate spectrum. Depending on the cultivation temperature B. (A.) adeninivorans exhibits different morphological forms and various post‐translational modifications and protein expression properties that are strongly correlated with the morphology. The genome has been completely sequenced and, in addition, there is a well‐developed transformation/expression platform, which makes rapid, simple gene manipulations possible. This yeast species is a very good host for homologous and heterologous gene expression and is also a useful gene donor. Blastobotrys (A.) adeninivorans is able to use a very wide range of substrates as carbon and/or nitrogen sources and is an interesting organism owing to the presence of many metabolic pathways, for example degradation of n‐butanol, purines and tannin. In addition, its unusual properties and robustness make it a useful bio‐component for whole cell biosensors. There are currently a number of products on the market produced by B. (A.) adeninivorans and further investigation may contribute further innovative solutions for current challenges that exist in the biotechnology industry. Additionally it may become a useful alternative to existing commercial yeast strains and as a model organism in research. In this review we present information relevant to the exploitation of B. (A.) adeninivorans in research and industrial settings. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of 7YSZ on the long-term stability of YTaO4 doped ZrO2 system

The long-term stability of Ta_0.16Y_0.16Zr_0.68O₂ (TaYSZ) has been studied for possible application in thermal barrier coatings. X-ray diffraction was used for the characterization of the phase stability from 1100 to 1500 °C. Long-term stability of TaYSZ in presence of 7YSZ at 1250 °C has also been checked. At 1500 °C, TaYSZ remains as a single tetragonal phase. TaYSZ, however, when treated at 1250 °C for 600 h decomposes to m-ZrO₂ and contains a minor YTaO₄ phase and t-TaYSZ. In the presence of 7YSZ, decomposition of TaYSZ was suppressed. Decomposition of TaYSZ follows a different mechanism when treated in air and under vacuum. TaYSZ once pretreated at 1500 °C does not show any decomposition when treated at 1250 °C for 600 h, though weak reflections of Y₃TaO₇ are seen in the X-ray diffraction pattern. The onset of sintering and the coefficient of thermal expansion (CTE) of TaYSZ have been found to be ∼1200 °C and 11.24 × 10⁻⁶ K⁻¹, respectively.     

Thermodynamic investigation of the austenite and the delta ferrite in the system Fe-Cr-Mn-N

The nitrogen solubility was measured in a wide range of temperatures including both the austenitic and the ferritic phase of iron-chromium-manganese alloys. The mass contents of the samples were 6.0 to 20.5 % Cr and 5.7 to 16.6 % Mn. Parameters describing the austenite and the delta ferrite in the system Fe-Cr-Mn-N were calculated analyzing all available experimental data. This evaluation yielded an improvement of the known parameters describing the austenitic phase by means of the regular solution model. At the first time, accurate thermodynamic parameters describing the delta phase both in the systems Fe-Mn-N and Fe-Cr-Mn-N could be deduced. By means of the phase diagram program package PD-pp the austenite-delta ferrite phase boundaries of the investigated alloys were calculated. They were compared with experimentally determined temperatures and nitrogen concentrations in the two-phase region. There is a good correspondence between theory and experiment. Using published data describing the melt a calculation of phase diagrams in the high temperature region can be performed.