Simultaneous determination of RRR- and SRR-α-tocopherols and their quinones in rat plasma and tissues by using chiral high-performance liquid chromatography

We established a method to simultaneously determine RRR- and SRR-α-tocopherol (α-Toc) and their quinones in biological samples by chiral-phase high-performance liquid chromatography (HPLC). α-Toc had a shorter retention time than α-tocopherylquinones (α-TQ), and 2-ambo-α-Toc was completely separated into two peaks; the first peak was RRR-α-Toc and the second SRR-isomer by chiral HPLC connected Chiralcel OD-H column and Sumichiral OA4100 column. In contrast, of the two peaks of α-TQ, the first was the SRR-isomer. We also investigated differences in the distribution of RRR- and SRR-α-TQ in rat tissues after oral administration of 2-ambo-α-Toc by the above HPLC method. Rats deficient in vitamin E were divided into two groups, control and experimental, and tissues were collected at 3, 6, and 24 h after oral 2-ambo-α-Toc administration. The concentrations of RRR- and SRR-α-Toc and their quinones in plasma and each tissue were determined. The concentration of SRR-α-TQ in plasma and adrenal glands was not significantly different from RRR-α-TQ. However, the concentration of SRR-α-TQ in liver up to 6 h after oral administration was higher than that of RRR-α-TQ, and SRR- and RRR-α-TQ levels were similar at 24 h after oral administration. Therefore, we may assume that the formation of α-TQ in vivo was not different between RRR- and SRR-isomer and that it was not affected by the presence of α-Toc stereoisomers.     

Crystallographic, thermoelectric, and mechanical properties of polycrystalline type-I Ba8Al16Si30-based clathrates

Crystallographic, thermoelectric, and mechanical properties of polycrystalline Ba₈Al₁₆Si₃₀-based samples with type-I clathrate structure prepared by combining arc melting and spark plasma sintering methods were investigated. The major phase of the samples was a type-I clathrate with an actual Al/Si ratio of ~15/31, strongly suggesting that framework deficiency was absent or was present in very low concentration in the samples. The Hall carrier concentration n of the samples was approximately 1 × 10²¹ cm^?3, which is lower than the values reported so far for the Ba₈Al₁₆Si₃₀ system. Other important material parameters of the samples were as follows: the density-of-states effective mass m* = 2.3m ₀, Hall mobility μ = 7.4 cm² V^?1 s^?1, and the lattice thermal conductivity κ _L = 1.2 W m^?1 K^?1. The thermoelectric figure of merit ZT reached approximately 0.4 (900 K) for a sample with n = 9.7 × 10²⁰ cm^?3. Simulation using the experimentally determined values of material parameters showed that ZT reached values >0.5 if the carrier concentration is optimized at about 3 × 10²⁰ cm^?3. Young’s, shear, and bulk moduli were estimated to be approximately 98, 39, and 117 GPa, respectively, and Poisson’s ratio was found to be 0.25 from the longitudinal and transverse velocities of sound, v _L = 6038 m/s and v _T = 3503 m/s, respectively, for a sample with ZT = 0.4. The coefficient of thermal expansion (CTE) ranged from approximately 8 × 10^?6 K^?1 to 10 × 10^?6 K^?1 (330–690 K), which is smaller than the values reported for Ba₈Ga₁₆Ge₃₀ and Sr₈Ga₁₆Ge₃₀ clathrates.     

Quantitative nuclear magnetic resonance spectroscopic determination of the oxyethylene group content of polysorbates.

Guidelines for the oxyethylene group (EO) content of polysorbates are set by the Food and Agriculture Organization/World Health Organization Joint Expert Committee on Food Additives. However, the classical titration method for EO determination is difficult and time-consuming. Here, we show that quantitative (1)H-nuclear magnetic resonance spectroscopy can determine the EO contents of polysorbates rapidly and simply. The EO signals were identified through comparisons with sorbitan monolaurate and poly(ethylene glycol) distearate. Potassium hydrogen phthalate was used as an internal standard. The EO contents were estimated from the ratio of the signal intensities of EO to the internal standard. Two nuclear magnetic resonance systems were used to validate the proposed method. The EO content of commercial polysorbates 20, 60, 65, and 80 was determined to be within the recommended limits using this technique. Our approach thus represents an additional or alternative method of determining the EO contents of polysorbates.     

Effect of moisture sorption of underwear material on clothing microclimate in a hot environment

In this study, to investigate the thermal comfort of underwear, it was experimentally evaluated how the moisture sorption of underwear material affected the transient condition on the clothing microclimate under the summer heat environment by using a perspiration thermal manikin. Three kinds of underwear with different mixed spinning rates of moisture absorbing synthetic fiber (MAS) were compared. It was shown that the higher the mixed spinning rate of MAS, the larger the decline of the humidity in the clothing was in insensible perspiration. In comparison, for PET70 with 100% cotton (COT100), though each of the official moisture regions was almost the same, the microclimate humidity declined more rapidly in COT100 and returned to the original humidity in a shorter time. The integration value of the humidity decline which returned to the original value was the same between the two materials. To show the effect of the initial condition of the material, the underwear in a moderate humid condition, which was 30^°C, 65% RH, was compared with one in a dry condition. The fall in the clothing microclimate of the humid condition was about one third that of the dry one. In sensible perspiration, though the humidity decline was seen, it returned to the original humidity faster than in the insensible condition. A temperature rise in the clothing and a temperature drop occurred as frequently as in the standard underwear during drying on the skin surface. This suggested that the endothermic reaction occurred as moisture desorbed. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20220     

Rare monomeric structure of CpRh(III) dithiolene complex: Combined ESR and electronic absorption studies on electrochemically generated Rh(II) species

The [CpRh^III(mnt)] (1) (Cp = η⁵-cyclopentadienyl, mnt = maleonitrile-1,2-dithiolate) was characterized as a rare monomeric structure. The CV of 1 showed a reversible reduction wave which attributed to Rh(II)/Rh(III) couple. UV–Vis spectral measurement during electrolysis using an OTTLE cell indicated that lifetime of electrochemically generated 1⁻ (Rh(II) species) was only a few seconds. Isotropic (g_iso = 2.045, A_iso = 1.15 mT) and anisotropic ESR (g₁ = 2.173, a₁ = 1.85 mT, g₂ = 1.982, a₂ = 0.98 mT) spectra of 1⁻ were observed while electrochemical reduction of 1. Both ESR spectra showed hyperfine splittings due to the central Rh (I = 1/2).     

Structural characterization of neutral glycosphingolipids by thin-layer chromatography coupled to matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight MS/MS

Rapid and convenient structural analysis of neutral glycosphingolipids (GSLs) was achieved by direct coupling of thin-layer chromatography (TLC) to matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight (MALDI-QIT-TOF) MS/MS. Positions of unstained GSL spots on developed TLC plates were determined by comparison to orcinol-stained references. A matrix solution of 2,5-dihydroxybenzoic acid (DHB) in acetonitrile/water (1:1 v/v) was then added directly to the unstained GSL spots, and the GSLs were directly analyzed by MALDI-QIT-TOF MS. The acetonitrile/water DHB solution proved to be suitable for MS/MS structural analysis with high sensitivity. MS/MS and MS/MS/MS of GSLs yielded simple and informative spectra that revealed the ceramide and long-chain base structures, as well as the sugar sequences. Hydroxy fatty acids in ceramide provided characteristic MS/MS fragment ions. GSLs were stained with primuline, a nondestructive dye, after TLC development, and successfully analyzed by MALDI-QIT-TOF MS/MS with high sensitivity. Immunostaining of GSLs after TLC development is a powerful method for characterizing antibody-specific sugars, but not ceramides. By coupling TLC-immunostaining of GSLs to MALDI-QIT-TOF MS/MS, we were able to identify both the sugar and the ceramide structures. The detection limits of asialo GM1 (Galbeta1-3GalNAcbeta1-4Galbeta1-4Glcbeta1-1'Cer) were 25 and 50 pmol in primuline staining and immunostaining, respectively.     

Material labeling of soft plastic toys and plasticizers in polyvinyl chloride products

We investigated the labeling and content of plasticizers of soft plastic toys. First, we investigated material labeling in 96 products purchased in fiscal years 2000 and 2001. Among these products, 43% of those purchased in fiscal 2000 and 68% of those purchased in fiscal 2001 were labeled. We then investigated the kinds and amounts of plasticizers in 73 soft polyvinyl chloride (PVC) toys. Three kinds of phthalates and six other kinds of plasticizers were detected in the soft PVC toys. Diisononyl phthalate, di(2-ethylhexyl) phthalate, diisononyl adipate, and O-acetyl tributyl citrate were detected at high frequency, and in large amounts. The average total content of all plasticizers was 280 mg/g for the products purchased in fiscal 2000 and 227 mg/g for those in fiscal 2001. In fiscal 2001, antioxidants, 4-nonylphenol, and bisphenol A were investigated in addition to plasticizers.     

NMR determination of crystallinity for poly(?-l-lysine)

Crystallinity of poly(?-l-lysine) (?-PL) was discussed by analyzing the differences in the ¹H spin-spin relaxation times (T₂^H), the ¹³C spin-lattice relaxation times (T₁^C), and the ¹³C NMR signal shapes between the crystalline and the non-crystalline phases. The observed ¹H relaxation curve (free induction decay followed by solid-echo method) showed the sum of Gaussian and exponential decays. Similarly, the observed ¹³C relaxation curves obtained from the Torchia method were double-exponential. The ¹³C NMR spectrum of ?-PL was divided into the narrow and the broad lines by utilizing the intrinsic differences in the ¹H spin-lattice relaxation times in the rotating-frame between them, which are attributed to the crystalline and the non-crystalline phases, respectively. Even though the crystallinity is obtained from the identical NMR measurements, the estimated values are different with each other. The crystallinity estimated from the T₂^H differences was 75.8 ± 0.1% at 333 K and 60.7 ± 0.4% at 353 K. From the T₁^C differences, the value was estimated to be 62 ± 11%. Furthermore, the value estimated from the NMR signal separation was 54 ± 5%. In this study we have explained these discrepancies by the difference in susceptibility among the experiments for the inter-phase, which exists in-between the crystalline and the amorphous phases. Furthermore, the estimated crystallinity was ascertained by the X-ray diffraction experiment.     

Accumulation of radiocesium in wild mushrooms collected from a Japanese forest and cesium uptake by microorganisms isolated from the mushroom-growing soils

Mushrooms and soils samples collected from a sub-alpine forest of Mt. Fuji in Japan were measured for 137Cs and stable Cs. The ranges of 137Cs specific activities and stable Cs concentrations in the mushrooms were 291-7950 Bq kg(-1) dry weight and 4.69-58.1 mg kg(-1) dry weight, respectively. Both 137Cs specific activities and stable Cs concentrations in the mushrooms were higher than those in common agricultural plants. The 137Cs specific activities and stable Cs concentrations in the soils were 3.18-149 Bq kg(-1) dry weight and 0.618-2.18 mg kg(-1) dry weight, respectively. The appearance frequencies of filamentous actinomycetes and planktonic bacteria from the soils decreased according to increasing Cs contents in the medium. No relationship was observed between the appearance frequencies of those and the stable Cs concentrations in the soils. The filamentous actinomycetes from any soil sample could not grow in the presence of 25 mM Cs, although the planktonic bacteria from the soil samples could grow with up to 50 mM Cs in YM agar. In addition, the planktonic bacteria from approximately 70% of the soil samples could grow even in the presence of 100 mM Cs. Filamentous actinomycetes were more sensitive to Cs than planktonic bacteria. In in vitro experiments, Cs uptake by these strains of filamentous actinomycetes and planktonic bacteria was high in the presence of 5 mM CsCl and the strains accumulated Cs, the same as in mushrooms. Our results indicate that filamentous actinomycetes in the soils have higher sensitivity to Cs than planktonic bacteria, and several strains of filamentous actinomycetes have a high Cs accumulation in the presence of 5 mM Cs.