大豆脂肪氧化酶酶活性变化研究

采用分光光度法对大豆中三种脂肪氧化酶（同工酶）进行检测并测定脂肪氧化酶活性,研究表明：大豆粉碎后随着贮存时间的延长,脂肪氧化酶活性逐渐降低,大豆发芽后脂肪氧化酶活性降低了43%.     

Distribution, diversity and regulation of alcohol oxidase isozymes, and phylogenetic relationships of methylotrophic yeasts

In this study, we attempted to classify the methylotrophic yeasts based on diversities of alcohol oxidase (AOD), i.e. zymogram patterns and partial amino acid sequences. According to zymogram patterns for AOD, members of the methylotrophic yeasts separate into two major lineages, one group involving strains having a single AOD and the other group, including Pichia methanolica, Candida pignaliae and C. sonorensis, showing nine AOD isozymes. Based on partial amino acid sequences of AOD, the methylotrophic yeasts could be divided into five groups, and this classification agrees mostly with grouping based on 26S domain D1/D2 rDNA nucleotide sequences, except for some strains. Moreover, the strains having AOD isozymes constitute one group with P. trehalophila, P. glucozyma and Pichia sp. strain BZ159, although these strains are divided into two types, based on amino acid sequences of second AODs. On the other hand, these AOD isozymes consist of two subunits; the first subunits are induced not only by methanol but also by glycerol and pectin, although the second subunits are mainly induced by methanol. These data indicate that AOD isozymes and second AOD genes distribute widely in several methylotrophic yeasts in the natural environment, and second AOD genes may have evolved as methylotrophic genes that can adapt to the environmental conditions of higher methanol concentrations.     

Investigation of pathways of advanced glycation end-products accumulation in macrophages

Advanced glycation end-products (AGE) play a role in the pathogenesis of several diseases, including diabetic complications and atherosclerosis. In atherosclerotic lesions of human aortas, AGE are localized in the extracellular matrix and intracellularly in foam cells. Two interpretations are possible for AGE accumulation inside macrophages, one is endocytic uptake of extracellular AGE-proteins by scavenger receptors; the other is intracellular AGE formation inside the macrophages. In the present study, we determined the pathways involved in AGE accumulation inside macrophages. RAW 264.7 cells, a murine macrophage cell line, incubated with BSA and 1600 mM glucose for 40 weeks, recognized heavily modified AGE- BSA. In contrast, the cells showed no ligand activity for mildly modified AGE-BSA, prepared by incubating BSA with 50 mM glucose for 24 weeks. Nepsilon-(carboxymethyl)lysine (CML)-modified proteins of about 65 kDa were detected in human monocyte-derived macrophages incubated for 7 days with 30 mM glucose and phorbol myristate acetate. Furthermore, CML was generated when glycated protein was incubated with hypochloric acid. Taken together, our results indicate that AGE detected inside foam cells in atherosclerotic lesions are generated intracellularly rather than representing endocytic uptake of extracellular AGE-proteins by scavenger receptors.     

Metabolic disturbance of tryptophan-nicotinamide conversion pathway by putative endocrine disruptors, bisphenol A and styrene monomer

Bisphenol A, a monomer of polycarbonate plastics, disturbed the conversion pathway of the amino acid tryptophan to the vitamin nicotinamide. The conversion ratio of tryptophan to nicotinamide was reduced to 1/15 by feeding a diet containing 1% bisphenol A. A putative disturbing reaction is kynurenine-->3-hydroxykynurenine, which is catalyzed by kynurenine monohydroxylase. This is an FAD-enzyme and requires NADPH as a coenzyme. Styrene monomer (1% addition to a normal diet) did not affect the food intake or the body weight, but slightly reduced the conversion ratio of tryptophan-nicotinamide.     

Fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds and common fire retardants

In this study, the fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds (didecyl dimethyl ammonium chloride (DDAC) and didecyl dimethyl ammonium tetrafluoroborate (DBF)) were compared with the performance of untreated control specimens and specimens treated with common fire retardants ((monoammonium phosphate (MAP), diammonium phosphate (DAP) and ammonium sulphate (AS)). Test specimens were treated with 1% and 4% (% m/v) aqueous solutions of the chemicals. The fire performance tests were the fire tube test (ASTM E 69) which measures mass losses in the specimens and the cone calorimeter test (ASTM E 1354) which measures mass loss, heat release rate, time for sustained ignition, effective heat of combustion, and specific extinction area. The results from the cone calorimeter tests were used to estimate the flame spread index (FSI) in the Steiner tunnel test (ASTM E 84). Heat release rates of the specimens treated with MAP, DAP, and AS were lower than those of both DDAC and DBF-treated specimens and the untreated control specimens. Compared with the untreated specimens, higher heat release rates were observed for the specimens treated with the quaternary ammonia compounds, DDAC and DBF. The estimates for the FSI for DDAC and DBF were for values equal to or higher than for the untreated control specimens. At higher concentration levels, MAP, DAP and AS were effective in decreasing initial contribution of heat release to potential fire. Decay resistance tests were done according to AWPA E 10 standard method using one brown-rot fungus and one white rot-fungus. Decay resistance tests revealed that solid wood specimens treated with DDAC and DBF showed resistance against the fungi tested, however, MAP, DAP and AS did not provide complete protection. While DBF and DDAC increased resistance of plywood specimens, high mass losses in plywood specimens treated with MAP, DAP and AS were obtained.     

Liquefaction and dechlorination of hydrothermally treated waste mixture containing plastics with glass powder

Additive effects of glass powder upon the product yields and chlorine distribution after liquefaction of hydrothermally pretreated mixed waste (HMW) are compared with liquefaction of HMW with any one of water, quartz sand, or glass powder plus water. As a result, addition of either water or quartz sand did not affect liquefaction and dechlorination of HMW. Further, water (5 g) addition did not enhance liquefaction and dechlorination of HMW with glass powder. On the other hand, after liquefaction of HMW with glass powder, the yields of chlorine in the gas and water insoluble constituents decreased and the chlorine yield in the water-soluble constituent increased significantly. Because sodium in glass powder dissolved in a small amount (0.5 g) of water resulted from dehydration of HMW during liquefaction. Further, hydrogen chloride derived from polyvinylchloride in HMW was neutralized by ion exchange between H(+) and Na(+) dissolved in a small amount of water forming NaCl in the Residue (water-soluble) constituent. Therefore, most of chlorine in HMW was removed easily by water extraction of the Residue constituent after liquefaction of HMW with glass powder. Further, upgrading of HMW into the oil constituent was enhanced due to inhibition of production of chlorine containing organic compounds. Accordingly, it was clarified that glass powder was the most effective additive for liquefaction and dechlorination of HMW.     

Am1 MO Study of Benzene Nitro Derivatives

Molecular properties of benzene nitro derivatives were investigated by using semi-empirical MO calculations. As the results, the molecular structures and the rotational barrier of the nitro group calculated by AM1 showed a good agreement with the experimental values. The heats of formation in gaseous and condensed phases were obtained by considering isodesmic reactions. By this procedure, the heat of formation of hexanitrobenzene in solid phase was calculated to be +22.7 kcal/mol. The detonation parameters were also calculated by using four equations of state. The predicted detonation velocities showed a good agreement with the experimental values.     

Crystallization and phase separation kinetics in blends of linear low-density polyethylene copolymers

We have systematically studied the crystallization and liquid-liquid phase separation (LLPS) kinetics in statistical copolymer blends of poly(ethylene-co-hexene) (PEH) and poly(ethylene-co-butene) (PEB) using primarily optical microscopy. The PEH/PEB blends exhibit upper critical solution temperature (UCST) in the melt and crystallization temperature below the UCST. The time evolution of the characteristic morphology for both crystallization and LLPS is recorded for blends at various compositions and following a quench from initial homogenous melts at high temperature to various lower temperatures. The crystallization kinetics is measured as the linear growth rate of the super structural crystals, whereas the LLPS kinetics is measured as the linear growth rate of the characteristic length of the late-stage spinodal decomposition. The composition dependence crystallization kinetics, G, shows very different characteristics at low and high isothermal crystallization temperature. Below 116 °C, G decreases with increasing PEB content in the blend, implying primarily the composition effect on materials transport; whereas at above 116 °C, G shows a minimum at about the critical composition for LLPS, implying the influence of the LLPS. On the other hand, LLPS kinetics at 130 °C is relatively invariant at different compositions in the two-phase regime. The length scale at which domains are kinetically pinned, however, depends strongly on the composition. In a blend near critical composition, a kinetics crossover is shown to separate the crystallization dominant and phase separation dominant morphology as isothermal temperature increases.     

Dietary Guar Gum Reduces Lymph Flow and Diminishes Lipid Transport in Thoracic Duct-Cannulated Rats

Guar gum has a well-recognized hypolipidemic effect. This effect is thought to be due to the physicochemical properties of guar gum, which may cause changes in adsorption of lipids or the viscosity of the intestinal contents. Guar gum is a non-specific absorption inhibitor of any type of lipid-soluble compound. Permanent lymph duct cannulation was performed on rats to investigate the effects of dietary guar gum on lymph flow and lipid transport. Rats fed a 5% guar gum diet were compared with those fed a 5% cellulose diet, and lymph was collected after feeding. The water-holding capacity (WHC), settling volume in water (SV), and viscosity of guar gum were compared with those of cellulose. Rats fed with the guar gum diet had significantly lower lymph flow and lymphatic lipid transport than did rats fed with the cellulose diet. The WHC, SV, and viscosity of guar gum were significantly higher than those of cellulose. We propose that dietary guar gum reduces lymph flow and thereby diminishes lipid transport by means of its physicochemical properties related to water behavior in the intestine.     

In-situ immobilization of Sr radioactive isotope using nanocrystalline hydroxyapatite

Hydroxyapatite was used as the inert matrix for in-situ immobilization of strontium (Sr) radioactive isotopes at room temperature. A nano-emulsification method was applied to synthesize Sr-substituted calcium hydroxyapatite (Ca_1?xSr_x)₁₀(PO₄)₆(OH)₂. The concentration of incorporated Sr was in the range of 0 ≤ x ≤ 1. Immobilization of Sr was evaluated using a stable isotope instead of radioactive isotope. The effect of strontium concentration on the crystal structure was studied and the results have showed that in the whole concentration range, Sr forms solid solutions with the host hydroxyapatite crystal structure. Powders comprised of nanometre sized particles were obtained and their properties, such as crystallite and particle size, changes in lattice parameters as function of dopant content and thermal stability, were further examined. It was found that the crystal structure of obtained powders is thermally stable at high temperatures. No secondary phases were formed in as-prepared powders or during calcination. The results in this study showed that nano-emulsion strategy provides a simple pathway for synthesis of a single-phase Sr-substituted hydroxyapatite, which can be used for immobilization of Sr radioactive isotopes.