Enhancement of valley splitting in (100) Si MOSFETs at high magnetic fields

We report the density and magnetic field dependence of the valley splitting of two-dimensional electrons in (100) Si metal–oxide–semiconductor field-effect transistors, as determined via activation measurements in the quantum Hall regime. We find that the valley activation gap can be greatly enhanced at high magnetic fields as compared to the bare valley splitting. The observation of strong dependence of the valley activation gap on orbital Landau level occupancy and similar behavior of nearby spin gaps suggest that electron–electron interactions play a large role in the observed enhancement.     

Über das chinoide Oxydationsprodukt des Benzal-di-β-naphthols

Ohne Zusammenfassung     

Efficient syntheses of benzothiazepines as antagonists for the mitochondrial sodium-calcium exchanger: potential therapeutics for type II diabetes

Type II diabetes mellitus is a chronic metabolic disorder that can lead to serious cardiovascular, renal, neurologic, and retinal complications. While several drugs are currently prescribed to treat type II diabetes, their efficacy is limited by mechanism-related side effects (weight gain, hypoglycemia, gastrointestinal distress), inadequate efficacy for use as monotherapy, and the development of tolerance to the agents. Consequently, combination therapies are frequently employed to effectively regulate blood glucose levels. We have focused on the mitochondrial sodium-calcium exchanger (mNCE) as a novel target for diabetes drug discovery. We have proposed that inhibition of the mNCE can be used to regulate calcium flux across the mitochondrial membrane, thereby enhancing mitochondrial oxidative metabolism, which in turn enhances glucose-stimulated insulin secretion (GSIS) in the pancreatic beta-cell. In this paper, we report the facile synthesis of benzothiazepines and derivatives by S-alkylation using 2-aminobenzhydrols. The syntheses of other bicyclic analogues based on benzothiazepine, benzothiazecine, benzodiazecine, and benzodiazepine templates are also described. These compounds have been evaluated for their inhibition of mNCE activity, and the results from the structure-activity relationship (SAR) studies are discussed.     

Total synthesis of (-)-reveromycin B

[structure: see text] The total synthesis of the epidermal growth factor inhibitor reveromycin B (2) is described. A novel, convergent, and stereoselective reaction sequence was utilized to construct the 5,6-spiroketal system 10 which was converted into the natural product 2 by a 16-step sequence.     

Determination of ultramicro amounts of sulphate as methylene blue—II The reduction

Sulphate may be determined spectrophotometrically as methylene blue after reduction to sulphide, which is allowed to react with p-aminodimethylaniline and ferric iron to form the dye. A previous paper¹ dealt with the colour reaction; this paper deals with the reduction.

A method for the reduction of sulphate to sulphide by hydriodic and hypophosphorous acids in acetic acid solution is proposed. It is founded on an investigation of the following variables: composition of the reducing reagent, composition of the carrier gas and gas-washing liquid, temperature at reduction, and time. The yield of the reduction is found to be 100% within the experimental errors. The standard deviation of a single determination of 100 μg S or 2 μg S is found to be 0.14 μg S or 0.05 μg S, respectively. Some interferences in connection with the application of the method for certain purposes are discussed.