Highly regioselective nucleophilic carbon-carbon bond formation on furans and thiophenes initiated by pummerer-type reaction

[reaction: see text] The reactions of (phenylsulfinyl)furans or -thiophenes with carbon nucleophiles in the presence of trifluoroacetic anhydride allowed the nucleophilic installation of carbon functional groups on the furan and thiophene nuclei with complete regioselectivity.     

An attempt directed toward enhanced shape selectivity in reversed-phase liquid chromatography: preparation of the dodecylaminated beta-cyclodextrin-bonded phase.

With the aim of preparing a stationary phase with a high shape-recognition ability for liquid chromatography, a new bonded phase was synthesized by coupling multiply dodecylamino-substituted beta-cyclodextrin (beta-CD) to 3-glycidoxypropyl-derivatized silica gel. The stationary phase prepared in this way was expected to have increased shape selectivity compared with that of conventional reversed-phase materials, due to solute interactions with the alkyl chain piles built up on the beta-CDs bonded to silica. The separation characteristics of the bonded phase were investigated using polycyclic aromatic hydrocarbons (PAHs) with different molecular shapes and compared with those of monomeric ODS and native beta-cyclodextrin-bonded phases. The newly developed stationary phase was found to be highly selective for PAHs.     

Czochralski-growth of germanium crystals containing high concentrations of oxygen impurities

Oxygen-containing germanium (Ge) single crystals with low density of grown-in dislocations were grown by the Czochralski (CZ) technique from a Ge melt, both with and without a covering by boron oxide (B₂O₃) liquid. Interstitially dissolved oxygen concentrations in the crystals were determined by the absorption peak at 855 cm⁻¹ in the infrared absorption spectra at room temperature. It was found that oxygen concentration in a Ge crystal grown from melt partially or fully covered with B₂O₃ liquid was about 10¹⁶ cm⁻³ and was almost the same as that in a Ge crystal grown without B₂O₃. Oxygen concentration in a Ge crystal was enhanced to be greater than 10¹⁷ cm⁻³ by growing a crystal from a melt fully covered with B₂O₃; with the addition of germanium oxide powder, the maximum oxygen concentration achieved was 5.5×10¹⁷ cm⁻³. The effective segregation coefficients of oxygen in the present Ge crystal growth were roughly estimated to be between 1.0 and 1.4.     

The structure of β-MAPI,a novel proteinase inhibitor

Structure of β-MAPI, a novel proteinase inhibitor produced by Streptomyces nigrescens WT-27, is determined as 1.     

Time-resolved total internal reflection fluorescence spectroscopy of polymer films

Using total internal reflection, the possibility of a subnanosecond fluorescence spectroscopy for elucidating photophysical and photochemical processes of polymer surface is demonstrated. The thickness which can be studied under the present experimental conditions is of the order of 0.01 μm.     

Bounds on multipartite entangled orthogonal state discrimination using local operations and classical communication

We show that entanglement guarantees difficulty in the discrimination of orthogonal multipartite states locally. The number of pure states that can be discriminated by local operations and classical communication is bounded by the total dimension over the average entanglement. A similar, general condition is also shown for pure and mixed states. These results offer a rare operational interpretation for three abstractly defined distancelike measures of multipartite entanglement.     

Simple and sensitive quantification of bioactive peptides in biological matrices using liquid chromatography/selected reaction monitoring mass spectrometry coupled with trichloroacetic acid clean-up

A simple and sensitive liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method has been developed for the quantification of bioactive peptides in biological fluids. The method employs protein precipitation with 4% trichloroacetic acid (TCA) and selected reaction monitoring (SRM) using an immonium ion as the product ion. This method was applied to determine the synthetic parathyroid hormone (PTH) analog (MW 1721) in rat plasma and human hepcidin-25 (MW 2789) in human serum. TCA clean-up showed a sufficient recovery for peptides with a MW of less than 3000, and would be useful as a simple and rapid method because of direct injection of the supernatant without evaporation or dilution. In addition, TCA clean-up allowed us not only to reduce sample preparation time, but also to select an immonium ion as a product ion of SRM, which led to detection more sensitive than SRM using other types of product ions. The lower limits of quantitation (LLOQs) of the PTH analog and the human hepcidin-25 were 0.2 ng/mL and 5 ng/mL, respectively. This method was fully validated with acceptable linearity, intra- and inter-assay precisions, and accuracy. Furthermore, this simple and rapid method is applicable to pharmacokinetic studies.