Partial synthesis of aromatic carotenoids,tedanin, agelaxanthin a,tethyatene, and renieratene

Aromatic carotenoids, tedanin, agelaxanthin A, and tethyatene were synthesized from 0- acetyl-6-citraurin derived from natural zeaxanthin, and tethyatene was further transformed into renieratene as the first example of aromatization of an alicyclic ring in carotenoids.     

Structure of Na2S–GeS2 glasses studied by using neutron and X-ray diffraction and reverse Monte Carlo modeling

Neutron and X-ray diffraction measurements were performed to investigate the structure of Na₂S–GeS₂ glasses synthesized by mechanical alloying. The Ge–S coordination numbers calculated from the total correlation functions show that GeS₄ tetrahedra form the basic framework structure of Na₂S–GeS₂ glasses. In addition, a three-dimensional structural model of the (Na₂S)₅₀(GeS₂)₅₀ glass was obtained by using reverse Monte Carlo (RMC) simulation on neutron and X-ray diffraction data, and it was compared with the RMC model previously obtained for a (Li₂S)₅₀(GeS₂)₅₀ glass. The results show that the Ge–S framework structures in the two glasses are almost the same in the short and intermediate ranges; that is, the Ge–S framework structures are formed mainly by the connection of corner-sharing GeS₄ tetrahedra. Many of the Na ions are coordinated by four S atoms, which are non-bridging S atoms and/or bridging S atoms.     

Application of digital phase-shift holographic interferometry to weak shock waves propagating at Mach 1.007

Digital phase-shift holographic interferometry was applied to visualize weak shock waves and related phenomena quantitatively. This method of interferometry is an improved version of double-exposure holographic interferometry using digital image processing and a phase shift method. The obtained interferograms were analyzed using the Carré method. To evaluate the applicability of the interferometry to quantitatively visualize the phenomena, density profiles behind weak spherical shock waves generated with 500 μg of silver azide were examined. The results of the numerical analysis performed with the hydrocode AUTODYN were compared with those of the experiment. The Mach number of visualized shock waves was estimated to be 1.007 ± 0.001 at the pressure transducer near the test section. At the shock fronts, the density difference between the experimental and numerical results was within 0.3%.     

Lebesgue piecewise affine approximation of nonlinear systems

This paper addresses a piecewise affine (PWA) approximation problem, i.e., a problem of finding a PWA system model which approximates a given nonlinear system. First, we propose a new class of PWA systems, called the Lebesgue PWA approximation systems, as a model to approximate nonlinear systems. Next, we derive an error bound of the PWA approximation model, and provide a technique for constructing the approximation model with specified accuracy. Finally, the proposed method is applied to a gene regulatory network with nonlinear dynamics, which shows that the method is a useful approximation tool.     

Nanoacorns: anisotropically phase-segregated CoPd sulfide nanoparticles

The anisotropically phase-segregated CoPd sulfide nanoparticles, named "CoPd nanoacorns", were spontaneously generated by reducing the corresponding metal precursors with 1,2-hexadecanediol in the presence of various alkanethiols. The CoPd nanoacorn consisting of crystalline Co9S8 and amorphous PdSx phases with the Co9S8 (001) plane at their interface was found to spontaneously form through the anisotropic growth of the Co9S8 phase after the generation of PdSx nanoparticles.     

Mechanism of asymmetric sulfimidation with N-alkoxycarbonyl azide in the presence of (OC)Ru(salen) complex

Spectroscopic analysis of imidation of alkyl aryl sulfides with N-2,2,2-trichloro-1,1-dimethylethyloxycarbonyl azide 2 in the presence of (OC)Ru(salen) complex 1 strongly suggests that an addition compound of the azide 2 to 1 is the active species for the imidation, while the addition compound undergoes the undesired intramolecular CH insertion onto the salen ligand of the complex in the absence of sulfide, directly or via the corresponding nitrene-ruthenium species.     

Improvement of dissolution properties of a new Helicobacter pylori eradicating agent (TG44) by inclusion complexation with beta-cyclodextrin

The interaction of a newly developed Helicobacter pylori eradicating agent (TG44, 4-methylbenzyl-4'-[trans-4-(guanidinomethyl)cyclohexylcarbonyloxy]biphenyl-4-carboxlylate monohydrochloride) with beta-cyclodextrin (beta-CyD) in aqueous solution and in solid state was studied to gain insight into the high in-vivo H. pylori eradicating activity of TG44/beta-CyD complex. The interaction was studied by the solubility method, spectroscopic methods, powder X-ray diffractometry and differential scanning colorimetry (DSC). TG44 gave A(L)-type phase solubility diagram with beta-CyD in water, showing a linear increase in solubility of the drug up to 8 mM beta-CyD concentration. The solubility of TG44 (0.04 mM in water at 25 degrees C) increased about 70-folds at 8 mM beta-CyD. Ultraviolet, circular dichroism, fluorescence and (1)H-nuclear magnetic resonance spectroscopic studies indicated that TG44 forms the inclusion complex with beta-CyD in a 1:1 stoichiometry and the biphenyl moiety of TG44 is preferably included in the beta-CyD cavity in water. The Giordano plot made by monitoring changes in the fusion enthalpy of TG44 (about 184 degrees C) suggested that TG44 forms the 1:1 complex with beta-CyD in the solid state. The TG44/beta-CyD solid complex in a 1:1 stoichiometry was prepared by the grinding and spray-drying methods and confirmed by powder X-ray diffractometry and DSC that the complex is in an amorphous state. The initial dissolution rate of TG44/beta-CyD complex was significantly faster than those of the drug alone and the physical mixture of both components, maintaining higher supersaturated concentrations of the drug for a long time. The results suggested that the higher eradicating activity of TG44/beta-CyD complex to Helicobacter pylori, compared with that of the drug alone, is attributable at least partly to the faster dissolving property of the complex and its ability to maintain the supersaturated state of the drug in the gastric fluid.     

Asymmetric catalysis of metal complexes with non-planar ONNO ligands: salen, salalen and salan

Chiral metal (M)-salen complexes are one of the most versatile asymmetric catalysts and the catalysis of trans-M(salen) complexes has been well cultivated. On the other hand, non-planar cis-beta M(salen) complexes were recently found to show unique asymmetric catalysis that cannot be attained by trans-M(salen) complexes. Moreover, related non-planar M(salalen) and M(salan) complexes were also found to exert unprecedented asymmetric catalysis. This Feature Article summarizes the seminal studies on asymmetric catalysis of non-planar M(ONNO) complexes, full utilization of which will provide marked improvement in asymmetric synthesis.     

High-molecular-weight poly(p-phenyleneterephthalamide) by CaCl2 promoted direct polycondensation with thionyl chloride in N-methylpyrrolidone

The direct polycondensation of terephthalic acid and p-phenylenediamine hydrochloride (PPD.2HCl) with thionyl chloride was found to be significantly promoted in N-methylpyrrolidone (NMP) by dissolved CaCl₂ and tertiary amines. The inherent viscosity of the polymer obtained varied with the amount of CaCl₂ and tertiary amines added. The reaction, when effectively promoted by CaCl₂, proceeded homogeneously in the early state of polycondensation, and then resulted in a highly swollen gel. CaCl₂ had to be present in the PPD.2HCl/tertiary amines/NMP solution as well as in the TPA/SOCl₂/NMP mixture for the polycondensation to proceed to high molecular weight. Complexes of CaCl₂, PPD.2HCl, and tertiary amines in NMP similar to the well known complex, CaCl₂ · nNH₃ (n = 2, 4, 8) was proposed to facilitate the polycondensation.