Cardiac glycosides: 3. synthesis of β-D-digitoxose analogues

Earlier studies have shown that the β-D-digitoxose (2,6-dideoxy-β-D-mannopyranose) directly attached to the cardiac glycoside steroid C3 has the greatest effect on biological activity. This report describes the synthesis of eight digitoxosides (2a-9a), with widely varying cyclic and acyclic C17β-side groups, and the corresponding C3',C4'-acetonides (2b-9b). NMR analysis of conformational strain introduced by the acetonide groups is supported by crystallographic analysis of the sugars' torsion angles.     

Production and utilization of amino acids.

The amino acid industry has been steadily expanding since monosodium glutamate was first marketed as a flavoring material in 1909. Its production has recently reached almost the 1 billion dollar level. Amino acids are produced by extraction from protein hydrolyzates, by fermentation with the aid of microorganisms, by enzymatic processes, and by chemical synthesis. To obtain natural L-amino acid, chemical synthesis generally requires two additional steps, i.e. optical resolution and racemization of the D isomer. The most important applications of amino acids include the fortification of plant food and feeds by supplementation of the deficient essential amino acid(s). Apart from their uses in the food industry, medical applications of amino acids (nutritional preparations and therapeutic agents) are becoming increasingly important.     

Superconducting Properties in Metallic Phase of NbS3

Metallic phase of NbS₃ was synthesized by heating the crystal of semiconducting NbS₃. Metallic NbS₃ undergoes superconducting transition around 2 K. The analysis of the angular dependence of the upper critical magnetic field suggests that the effect of filmy or fibrous morphology plays an important role in the superconducting properties.     

Preparation of polymethyl methacrylate with well-controlled stereoregularity by anionic polymerization in an ionic liquid solvent

This study investigates the effect of ionic liquids (ILs) on the anionic polymerization of methyl methacrylate (MMA). Polymethyl methacrylate (PMMA), an isotactic polymer, is prepared by anionic polymerization at a high reaction temperature with an IL that acts as both solvent and additive. The most plausible reaction mechanism is determined using ¹H NMR and Fourier-transform infrared spectroscopy. The electrostatic interaction between MMA and the IL increases the apparent steric hindrance in MMA, resulting in the isotactic PMMA.     

Evaluation of light scattering properties and chromophore concentrations in skin tissue based on diffuse reflectance signals at isosbestic wavelengths of hemoglobin

Optical Review - We investigate a method to evaluate light-scattering properties and chromophore concentrations in human skin tissue through diffuse reflectance spectroscopy using the reflectance...     

Direct Introduction of a Dimesitylboryl Group Using Base‐Mediated Substitution of Aryl Halides with Silyldimesitylborane

The first dimesitylboryl substitution of aryl halides with a silylborane bearing a dimesitylboryl group in the presence of alkali‐metal alkoxides is described. The reactions of aryl bromides or iodides with Ph₂MeSi?BMes₂ and Na(OtBu) afforded the desired aryl dimesitylboranes in good to high yields and with high borylation/silylation ratios. Selective reaction of the sterically less‐hindered C?Br bond of dibromoarenes provided monoborylated products. This reaction was used to rapidly construct a D‐π‐A aryl dimesityl borane with a non‐symmetrical biphenyl spacer.     

Color adjustment algorithm adapted to the spectral reflectance estimation method

We are developing a daily health monitoring system that uses mobile phones with cameras and analyzes physiological conditions from R, G, and B intensity levels. However, since it is affected by various imaging conditions of the image input, color correction is required for accurate health monitoring. Therefore, we developed and validated a colorcorrection algorithm to derive reliable color information by correcting the spectral reflectance using the Wiener estimation and a color chart.     

Control of the size and characteristic features of fluorine-containing aromatic polyamide particles

Nano-sized aromatic polyamide particles with trifluoromethyl groups were prepared via a precipitation polymerization method from 4,4′-diphenyldicarbonyl chloride and 2,2-bis(4-aminophenyl)hexafluoropropane in a dioxane solution containing pyridine. The average diameter of the particles decreased from ca. 500 to 150 nm as the pyridine content increased. The particles were spherical with narrow size distributions. Also, the inherent viscosity and yield of the particles decreased gradually as the pyridine content increased. For all the particles, the degrees of crystallinity were low, and the thermal decomposition temperatures were above 457 °C. The addition of pyridine significantly influenced not only the polymerization but also the affinity between the product and the reaction solution, resulting in a difference in the diameters and characteristic features of the particles. Furthermore, these characteristic features were found to be determined predominantly during precipitation from the reaction solution. Meanwhile, trifluoromethyl groups in the particles had significant influence on the morphology and characteristic features of the particles.     

Improvement of spatial homogeneity in GdBCO/IBAD-MgO coated conductor

Recent process optimization allows improving homogeneity and a significant increase of J_c in GdBa₂Cu₃O_7-δ deposited on ion-beam assisted deposited MgO template (GdBCO/IBAD-MgO). We applied low-temperature laser scanning microscopy and laser scanning thermo-electric microscopy (LSTEM) to investigate local dissipation and defects simultaneously in recent GdBCO/IBAD-MgO coated conductor. By using high-resolution LSTEM, we could detect current blocking obstacles which are responsible for the large scale local dissipation. Data on the present GdBCO/IBAD-MgO coated conductors point out a significant reduction of current blocking obstacles compared to the previous process. We have shown the improvement of spatial homogeneity in the recent GdBCO/IBAD-MgO coated conductors. Current blocking obstacles are much less densely distributed as compared to previous YBCO/IBAD-GZO coated conductor. Obstacles larger than several micrometer significantly increase local dissipation whereas smaller defects do not influence it noticeably. 2D map of the phase delay component of the thermoelectric voltage lock-in signal is effective to analyze current blocking obstacles having action upon local dissipation.