Density of States of GaAs-AlGaAs Heterostructures Deduced from Temperature Dependend Magnetocapacitance Measurements

Abstract We have analyzed the density of states of a two dimensional electron gas in a GaAs- AlGaAs hetereostructure by measuring the magnetocapacitance in magnetic fields up to 6 Tesla at temperatures below 10 K. The experimental data are well described by a Gaussian-like density of states where the linewidth à is proportional to B

Density of States in Landau Level Tails of GaAs-AlxGa1-xAs Heterostructures

From an analysis of the thermally activated resistivity as a function of the magnetic field in the quantum Hall regime we deduced the position of the Fermi energy in the mobility gap as a function of the filling factor and therefore the density of states. The measured density of states is best described by a Gaussian like profile superimposed on a constant background

Excited states and electron transfer reactions of C₆₀(OH)₁₈ in aqueous solution

Dynamic light scattering of fullerenol solutions [C60(OH)18] reveals evidence for the formation of fullerene aggregates at high solute concentration (up to 3.85×10-2 mol dm-3). This hydrophilic fullerene derivative emits very weak fluorescence regardless of its concentration. Photolysis (35 ps; λex=355 nm) of C60(OH)18 in aqueous solution yields the immediate formation of a transient singlet excited state with broad absorption in the 550–800 nm region with ε670nm=2130 d mol-1 cm-1. The energetically higher-lying singlet excited state transforms via intersystem crossing (i.e., with τ1/2=500 ps) to the also broadly absorbing (550-800 nm), triplet excited state. In contrast, at low solute concentration, the features of the (∗T1→∗Tn) absorption differ significantly exhibiting an absorption maximum at 650 nm concomitant to a shoulder at 570 nm. The π-radical anion of fullerenol, [C60(OH)18]·−, generated by electron transfer from hydrated electrons and (CH3)2C(OH) radicals, absorbs with λmax at 870, 980 and 1050 nm. Based on electron transfer studies with suitable electron donor/acceptor substrates, the reduction potential of the C60(OH)18/[C60(OH)18]·− couple was estimated to be in the range between -0.358 and -0.465 V vs. NHE

ATR-FTIR spectroscopy reveals genomic loci regulating the tissue response in high fat diet fed BXD recombinant inbred mouse strains

Background: Obesity-associated organ-specific pathological states can be ensued from the dysregulation of the functions of the adipose tissues, liver and muscle. However, the influence of genetic differences underlying gross-compositional differences in these tissues is largely unknown. In the present study, the analytical method of ATR-FTIR spectroscopy has been combined with a genetic approach to identify genetic differences responsible for phenotypic alterations in adipose, liver and muscle tissues. Results: Mice from 29 BXD recombinant inbred mouse strains were put on high fat diet and gross-compositional changes in adipose, liver and muscle tissues were measured by ATR-FTIR spectroscopy. The analysis of genotype-phenotype correlations revealed significant quantitative trait loci (QTL) on chromosome 12 for the content of fat and collagen, collagen integrity, and the lipid to protein ratio in adipose tissue and on chromosome 17 for lipid to protein ratio in liver. Using gene expression and sequence information, we suggest Rsad2 (viperin) and Colec11 (collectin-11) on chromosome 12 as potential quantitative trait candidate genes. Rsad2 may act as a modulator of lipid droplet contents and lipid biosynthesis; Colec11 might play a role in apoptopic cell clearance and maintenance of adipose tissue. An increased level of Rsad2 transcripts in adipose tissue of DBA/2J compared to C57BL/6J mice suggests a cis-acting genetic variant leading to differential gene activation. Conclusion: The results demonstrate that the analytical method of ATR-FTIR spectroscopy effectively contributed to decompose the macromolecular composition of tissues that accumulate fat and to link this information with genetic determinants. The candidate genes in the QTL regions may contribute to obesity-related diseases in humans, in particular if the results can be verified in a bigger BXD cohort

Preparation of functional coatings for display glass applications by sol-gel derived techniques

Thin glasses are very important for display applications. If high bending strength is required, state-of-the-art technologies cannot be applied due to the small thickness. SiO2 coatings derived from tetraorthosilicate and also from a methyl modified silane in combination with a nanoparticulate silica sol are applied to 0 5 nn thick soda-lime glasses by dipping and are fired at 500°C. The bending strength of the glass (double ring method) is increased from about 450 MPa to 1100 MPa by a combination of filling and clamping of the micro flaws in the glass surface. An organic-inorganic coating of only 10 µm in thickness is introduced, which can protect 2 mm thick float glass with extremely high bending strength (600 MPa) completely against the mechanical load of a sand falling test, whereas the bending strength of uncoated float glass is decreased down to 10 % of its initial value by this test. In addition, coatings with optical functions, useful for display applications like antireflective properties, NIR reflectance or colour neutral absorbance of visible light for contrast enhancement, are introduced briefly

High-dose Vitamin D Supplementation in Multiple Sclerosis - Results From the Randomized EVIDIMS (Efficacy of Vitamin D Supplementation in Multiple Sclerosis) Trial

Background: Epidemiological, preclinical, and non-interventional studies link vitamin D (VD) serum levels and disease activity in multiple sclerosis (MS). It is unclear whether high-dose VD supplementation can be used as an intervention to reduce disease activity. Objectives: The study aimed to compare the effects of every other day high- (20,400 IU) versus low-dose (400 IU) cholecalciferol supplementation on clinical and imaging markers of disease activity in patients with relapsing-remitting MS or clinically isolated syndrome. Methods: The EVIDIMS (efficacy of vitamin D supplementation in multiple sclerosis) trial was a multicentre randomized/stratified actively controlled explorative phase 2a pilot trial with a double-blind intervention period of 18 months, add on to interferon-β1b. Results: Fifty-three patients were randomized, and 41 patients completed the study. Cholecalciferol supplementation was well tolerated and safe in both arms. After 18 months, clinical (relapse rates, disability progression) and radiographical (T2-weighted lesion development, contrast-enhancing lesion development, brain atrophy) did not differ between both treatment arms. Post-study power calculations suggested that the sample size was too low to prove the hypothesis. Conclusions: The results neither support nor disprove a therapeutic benefit of high-dose VD supplementation but provide a basis for sound sample size estimations in future confirmatory studies. www.clinicaltrials.gov/NCT01440062

Intersecting 6-branes from new 7-manifolds with G_2 holonomy

We discuss a new family of metrics of 7-manifolds with G_2 holonomy, which are R^3 bundles over a quaternionic space. The metrics depend on five parameters and have two Abelian isometries. Certain singularities of the G_2 manifolds are related to fixed points of these isometries; there are two combinations of Killing vectors that possess co-dimension four fixed points which yield upon compactification only intersecting D6-branes if one also identifies two parameters. Two of the remaining parameters are quantized and we argue that they are related to the number of D6-branes, which appear in three stacks. We perform explicitly the reduction to the type IIA model.Comment: 25 pages, 1 figure, Latex, small changes and add refs, version appeared in JHE