Masahiro Kobashi

Quantitative microanalysis of capsaicin, dihydrocapsaicin and nordihydrocapsaicin using mass fragmentography

A mass fragmentographic method for the quantitative microanalysis of capsaicin, dihydrocapsaicin and nordihydrocapsaicin in the fruits of Capsicum annuum has been developed. The molecular ions at m/e 377, 379 and 365 in the mass spectra were used for monitoring the trimethylsilyl derivatives of capsaicin, dihydrocapsaicin and nordihydrocapsaicin, respectively. The ratios of the height of each molecular ion to that of an internal standard (cholestane) were linear over the range 5-60 ng. The purification of individual capsaicinoids by high-performance liquid, thin-layer and gas-liquid chromatography is also described.

Electronic structure of polyiminovinylene as a tractable model for polyaniline

Abstract The electronic structures of polyiminovinylene (PIV) as well as polyaniline (PAn) are studied theoretically using the one-dimensional tight-binding self consistent field-crystal orbital (SCF-CO) method. PIV was employed as a tractable model for PAn to inspect the electronic process when the redox states of PAn are changed. The conduction mechanism caused by partial protonation (oxidation) is discussed and the possibility of the formation of bipolaron in the partially protonated polymer skeleton is examined.

Peculiar magnetic property of pyrolytic carbon prepared from adamantane

Magnetic‐property measurements of pyrolytic carbon prepared by the thermal chemical vapor deposition of adamantane were carried out using the Faraday balance method and the electron‐spin‐resonance (ESR) spectroscopy. Two kinds of samples under different preparation batches were employed to examine the batch dependence as well as the magnetic properties of each. The content of ferromagnetic metallic oxide as impurity in these samples has been confirmed to be low enough not to influence the present magnetic‐property measurements. Analysis of the magnetization curves observed in the magnetic field range 0–5 T has shown that these samples are basically superparamagnetic and, even, ferromagnetic at low temperature in one sample. The ESR measurements have also supported these aspects. The connection of the magnetic properties and batch dependence obtained here will be discussed in detail.

Isolation and characterization of 6-hydroxymethylpterin as the Crithidia growth-promoting factor from spinach chloroplasts☆

2-Amino-4-hydroxypteridine compounds were isolated as the Crithidia factor from spinach chloroplasts by DEAE-Sephadex A-50, DEAE-cellulose, Sephadex G-25, and thin-layer chromatography. One of the compounds was characterized as 6-hydroxymethylpterin by gas-liquid chromatography-mass spectrometry and by comparison with authentic specimen.

[81] Intracellular distribution, purification, and properties of dihydrofolate synthetase from pea seedlings

Publisher Summary This chapter discusses the purification and properties of dihydrofolate synthetase obtained from pea seedings. The chapter describes an assay for dihydrofolate synthetase activity that is based on the microbiological assay with Lactobacillus casei ATCC 7469. 7,8-Dihydropteroic acid used as substrate is prepared from pteroic acid by reduction with sodium dithionite as described by Futterman for reduction of folic acid to 7,8-dihydrofolic acid. The reagents are added to a tube in a total volume of 1.0 ml. The reaction is started by the addition of the enzyme. After incubation at 37° for 30 min, the reaction is stopped by heating the whole in a boiling water bath for 1 min. An aliquot of the reaction mixture is added to the single basal medium for folic acid in a final volume of 10 ml. For purification, the enzyme can be partially stabilized in the presence of 0.8-2 M ammonium sulfate and 50 mM 2-mercaptoethanol, although the enzyme in cell-free extracts from whole pea seedling is quite unstable. In contrast, the enzyme in the mitochondrial fraction is found to be fairly stable and easily solubilized by more than 95% only when in the suspending buffer.

Electronic structures of poly(carbon disulfide) and poly(carbon diselenide)

Abstract The electronic structures of poly(carbon disulfide) (PCS) and poly(carbon diselenide) (PCSe) have been studied using the one-dimensional tight-binding SCF-CO (self-consistent field-crystal orbital) method. The most energetically stable structures determined by the numerical energy gradient calculations favour not the trans -skeleton but the cis -skeleton of both PCS and PCSe. The conduction mechanism of the p-type and n-type doped PCS, based on the band structures obtained, is predicted to be different.

Change in electrical conductivity of doped coal

Abstract It has been demonstrated that bituminous coal can be doped by I2, Br2, and AsF5 resulting in the increase of the electrical conductivity by seven orders of magnitude at maximum. In the I2- and the AsF5-doped samples, the dopant species seem to remain in the sample without severe decomposition. The present experiment can be regarded as the first attempt of testing coal as electronic material.

Peculiar Magnetic Property of Pyrolytic Carbon Prepared From Adamantane

Abstract Magnetic-property measurements of pyrolytic carbon prepared by the thermal CVD of adamantane were carried out using the Faraday balance method and the ESR spectroscopy. The content of ferromagnetic metallic oxide as impurity in the samples has been confirmed to be low enough not to influence on the present magnetic-property measurements. Analysis of the measurement results has shown that the sample obtained are basically superparamagnetic and, even, ferromagnetic at low temperatures in a certain sample.

Isolation and characterization of 6-hydroxymethylpterin as a Crithidia growth-promoting factor from spinach chloroplasts.

Publisher Summary This chapter discusses the characterization of 6-hydroxymethylpterin as a Crithidia growth-promoting factor from spinach chloroplasts. The 6-hydroxymethylpterin has been isolated from spinach chloroplasts by chromatography on DEAE-Sephadex and cellulose columns that is the usual method to separate natural folate compounds. Phenolic compounds in whole leaves and folate derivatives that have been found present at 100-fold greater concentration than pteridine compounds, but have similar fluorescence maxima, sometimes interfere with the fluorimetric method used to identify pteridine compounds in leaves. In contrast, 2-amino-4-hydroxy-6-alkylpteridines (6-alkylpterins) promote growth of the trypanosomid flagellate Crithidia fasciculata when grown on a chemically defined medium limited in folic acid. The response to 6-alkylpterins is about 1000 times lower than that of folate derivatives. Thus, a fluorimetric method, using excitation at 360 nm and emission at 440 nm, and a biological assay procedure, using C. fasciculata as the test organism, are used to quantify 6-alkylpterin compounds during their isolation from spinach chloroplasts. To identify the pterins, gas liquid chromatographymass spectrometry is used. This chapter describes in detail the isolation of Crithidia factor from chloroplasts. Elution profile of the Crithidia factor from a Sephadex G-25 column is also discussed in this chapter.