Localization in Abelian Categories

We construct a generic Hall algebra of the Kronecker algebra and prove that its twisted version is a polynomial algebra in infinitely many variables over the twisted generic composition algebra. The variables are explicitly given as some central elements in the generic Hall algebra.

Thus, we obtain generic versions in the Kronecker case of theorems by Hua-Xiao and Sevenhant-Van den Bergh.     

Oxidation of ultra-thin Ti films on Mo(100): Soft X-ray photoelectron spectroscopy study

Titanium oxide films grown on Mo(100) have been investigated by low-energy electron diffraction (LEED) and soft X-ray photoelectron spectroscopy (PES). The film was grown by Ti deposition on Mo(100) and subsequent oxidation of the film by 12 L of O₂ exposure at room temperature. As the film was annealed at 700–1000 °C, the film in which the Ti atoms were in a Ti³⁺ oxidation state was formed. As the film was annealed at 1100–1500 °C, the oxidation state of Ti in the film was converted to Ti²⁺. The valence electronic structure of the film was measured under the condition that the emission from the Mo substrate was minimized due to a Cooper minimum of the Mo 4 d photoionization cross sections (hν = 100 eV). It was found that the Ti 3 d band in normal-emission spectra was increased in intensity when the film was annealed at 1100–1500 °C. As the film was annealed at 1300 °C for 10 s and 20 s, the film-covered Mo(100) gave (2 × 2) and (4 × 1) LEED patterns, respectively. The two-dimensional band structure of the (2 × 2) system was investigated by angle-resolved PES, and it was found that the film with a (1 × 1) periodicity with respect to the Mo(100) substrate existed in the (2 × 2) system.     

Synthesis of gentianine N-oxide by enzymatic hydrolysis of swertiamarin in the presence of hydroxylamine and reaction pathway to gentianine and gentianol

Gentianine is a metabolite of gentiopicroside and swertiamarin. Several biological activities have been reported for gentianine, such as antiinflammatory and antidiabetic activity, and hypotensive effect. Gentiopicroside is found in 0.9–9.8% content in Gentian root or Gentian scabra root, and Swertiamarin is contained in Swertia herb in 2–10%. These natural products can be potential starting materials for the synthesis of gentianine. This study describes the β-glucosidase-catalyzed hydrolysis of gentiopicroside and swertiamarin in the presence of hydroxylamine to afford gentianine N-oxide, which can be a synthetic precursor of gentianine derivatives. Enzymatic hydrolysis of swertiamarin selectively afforded gentianine N-oxide in 81% yield, whereas gentiopicroside afforded gentianine N-oxide and gentianol N-oxide. Plausible reaction pathways leading to gentianine, gentianol, and their N-oxides were also investigated.     

Conformational study of the cembranoid sarcophytol A, a potent anti-tumor-promoter

Conformational analysis of the marine cembranoid sarcophytol A (1a), a potent anti-tumor promoter, was carried out using a newly introduced molecular mechanic and molecular dynamic program Discover. Four minimum-energy conformations were derived, in accordance with a previous results of the epoxidation of 1a, which afforded 7R,8R/7S,8S- and 11R,12R/11S,12S-epoxide pairs. The most stable conformation was the one having C-19 and C-20 directed opposite to C-18, with respect to the average plane of the fourteen-membered ring. X-Ray crystallography of sarcophytol A alpha-methoxy-alpha-trifluoromethylphenylacetate (1c) was carried out simultaneously. This confirmed the 14S absolute configuration of 1a but the conformation of crystalline 1c did not correspond to any of the four minimum-energy conformers of 1a.     

Interacting Brownian motion in a periodic potential

We study transport properties of a system composed of Brownian particles immersed in a periodic potential. Interaction among the Brownian particles is treated perturbationally in a framework of a generalized Fokker-Planck equation, which due to the interaction contains a renormalized periodic potential and an extra mean field term. We solve the kinetic equation numerically and discuss effects of the (repulsive) interaction on dynamic response functions and transport coefficients.     

Experimental Correspondence between Spore Dosimetry and Spectral Photometry of Solar Ultraviolet Radiation

Abstract— The biologically effective dose of solar UV radiation was estimated from the inactivation of UV-sensitive Bacillus subtilis spores. Two types of independent measurements were carried out concurrently at the Aerological Observatory in Tsukuba: one was the direct measurement of colony-forming survival that provided the inactivation dose per minute (ID/min) and the other was the measurement of the spectral irradiance by a Brewer spectrophotometer. To obtain the effective spectrum, the irradiance for each 1 nm wavelength interval from 290 to 400 nm was multiplied with the efficiency for inactivation derived from the inactivation action spectrum of identically prepared spore samples. Integration of the effective spectrum provided the estimate for ID/min. The observed values of ID/min were closely concordant with the calculated values for the data obtained in four afternoons in 1993. The average ratio (±SD) between them was 1.24 (±0.16) for 14 data points showing high inactivation rates (<0.05 ID/min). Considering difficulties in the absolute dosimetry of UV radiation, the concordance was satisfactory and improved credibility of the two types of monitoring systems of biologically effective dose of solar UV radiation.     

ACTION SPECTRA IN ULTRAVIOLET WAVELENGTHS (150-250 nm) FOR INACTIVATION AND MUTAGENESIS OF Bacillus subtilis SPORES OBTAINED WITH SYNCHROTRON RADIATION

Bacillus subtilis spores were exposed in vacuo to monochromatic UV radiation from synchrotron radiation in the wavelength range of 150 nm to 250 nm. Survival and frequency of mutation to histidine-independent reversion were analysed for three types of spores differing in DNA-repair capabilities. UVR spores (wild-type DNA repair capability) exhibited nearly equal sensitivity to the lethal effects of far-UV (220 nm and 250 nm) and of vacuum-UV radiation (150 and 165 nm), but showed marked resistance to 190 nm radiation. UVS spores (excision-repair and spore-repair deficient) and UVP spores (a DNA polymerase I-defective derivative of UVS) exhibited similar action spectra; pronounced sensitivity at 250 and 220 nm, insensitivity at 190 nm and a gradual increase of the sensitivity as the wavelength decreased to 165 nm. In all strains, the action spectra for mutation induction paralleled those for the inactivation, indicating that vacuum-UV radiation induced lethal and mutagenic damages in the spore DNA. The insensitivity of the spores to wavelengths around 190 nm may be explicable by assuming that radiation is absorbed by materials surrounding the core in which DNA is situated.     

Properties of composite proton-conducting membranes prepared from three-dimensionally ordered macroporous polyimide matrix and polyelectrolyte

A new proton-conducting composite membrane has been prepared by use of a three-dimensionally ordered macroporous matrix of polyimide and a proton-conducting gel polymer; the resulting composite membrane exhibited very high conductivity of 1.7 x 10-1 S cm-1 at 60 degrees C under 90% relative humidity.     

Synthesis of molybdenocene(IV) and tungstenocene(IV) tropolonato complexes: Its derivative containing calix[4]arene moiety

The cationic di-μ-hydroxo dinuclear complexes of molybdenocene and tungstenocene [Cp₂M(μ-OH)₂MCp₂]⁺ (Cp = η-C₅H₅; M = Mo or W) react with tropolone to afford corresponding tropolonato complexes [Cp₂M(trop)]⁺ (trop = C₇H₅O₂). The products were investigated by IR, ¹H NMR, and ¹³C NMR spectroscopy as well as by X-ray crystallography (M = W). The structure shows that the central metal is surrounded by a distorted tetrahedral array of the two centers of cyclopentadienyl ligands and the two oxygen atoms of tropolonato ligand. The reaction has been extended to the synthesis of calix[4]arene receptor functionalized at the 1,3-positions of the upper rim with two tropolonato-molybdenocene centers.