铌酸催化合成乙酸苯乙酯

将铌酸用于催化合成乙酸苯乙酯 ,在醇酸摩尔比 1∶5 ,回流反应 2h ,催化剂用量 (以 1mol醇计 )为 5g的条件下 ,酯收率可达 84 .3%以上。催化剂不经处理 ,可多次循环使用 ,不污染环境 ,相对于一些其他催化剂 ,具有明显的优点。     

苯酚类物质对氨氮生物硝化的抑制研究

随着人类生活水平的提高,对环境的要求也逐渐提高,尤其是对水质的关注,据报道,近年来有毒有害物质对水体的污染程度有所增加,所以本实验着重研究对氨基苯酚、2,4-二氯苯酚对氨氮生物的硝化细菌的抑制作用以及两者的比较,从而为水体污染处理提供一些依据。实验选取富含硝化细菌的活性污泥作为富集培养的对象,采用间歇式反应器,通过逐渐提高基质——NH3-N浓度并加入相应比例的硝化细菌富集培养液对硝化细菌进行定向富集培养,并对氨氮、亚硝态氮、硝态氮三个出水指标进行监测,研究不同浓度的对氨基苯酚、2,4—二氯苯酚对氨氮生物硝化过程的影响,并得出抑制类型和其半致死浓度。     

Enzymatic esterification of glycerol III. Lipase-catalyzed synthesis of regioisomerically pure 1,3-sn-diacylglycerols and 1 (3)-rac-monoacylglycerols derived from unsaturated fatty acids

Lipases that display high regioselectivities and broad substrate tolerance were used as catalysts for the efficient esterification of glycerol under the conditions of irreversible acyl transfer. A variety of unsaturated fatty acids, such as oleic, linoleic, erucic, ricinolic, hydroxystearic and coriolic acid, were used for this purpose in the form of their vinyl esters. Suitable biocatalysts were chosen on the basis of systematic screening experiments regarding their regioselectivities (RE) and substrate tolerances. Distinct differences were found and expressed in numerical RE values as a measure for differences of these biocatalysts as being specific, selective, and nonspecific. Based on these experiments, a variety of molecules were synthesized on a preparative scale (>150 mmol) in good yield (ca.85%) and with high regioisomerical purities (>95% RE).     

Analysis of Volatiles Induced by Oviposition of Elm Leaf Beetle Xanthogaleruca luteola on Ulmus minor

Egg deposition of the elm leaf beetle Xanthogaleruca luteola causes the emission of volatiles from its food plant, Ulmus minor. These volatiles are exploited by the egg parasitoid, Oomyzus gallerucae, to locate its host. In contrast to other tritrophic systems, the release of volatiles is not induced by feeding but by egg deposition. Previous investigations showed that the release is systemic and can be triggered by jasmonic acid. Comparison of headspace analysis revealed similarities in the blend of volatiles emitted following egg deposition and feeding. The mixture consists of more than 40 compounds; most of the substances are terpenoids. Leaves next to those carrying eggs emit fewer compounds. When treated with jasmonic acid, leaves emit a blend that consists almost exclusively of terpenoids. Dichloromethane extracts of leaves treated with jasmonic acid were also investigated. After separation of extracts of jasmonate induced elm leaves on silica, we obtained a fraction of terpenoid hydrocarbons that was attractive to the parasitoids. This indicates that jasmonic acid stimulates the production of terpenoid hydrocarbons that convey information of egg deposition to the parasitoid.     

铌酸催化合成苹果酯-B的研究

以铌酸为催化剂,由乙酰乙酸乙酯和1,2－丙二醇合成了苹果酯－B,考察了影响收率的因素,其最佳条件为：乙酰乙酸乙酯与1,2－丙二醇的比为：1：1．5(mol/mol),催化剂用量为反应物质量的1．5％,带水剂用量为反应物体积的42．2％,反应在回流温度下进行,反应时间2．5hn,收率达83．4％。     

Interspecific response to sex pheromones,and calling behavior of severalAttagenus species (Coleoptera: Dermestidae)

Females of severalAttagenus species demonstrated calling behaviors similar to those previously reported forA. elongatulus. Attagenus rufipennis females did not call until they were 12–14 days old. OtherAttagenus species called at approx. 4 days of age. All species exhibited diurnal periods of calling activity. Interspecific pheromone responses were tested, withA. megatoma megatoma, A. megatoma canadensis, A. megatoma japonicus, andA. schaefferi spurcus showing equal cross-responses. Male response to females was demonstrated inA. rufipennis andA. bicolor. Attagenus rufipennis, bicolor, andelongatulus males responded only to female extracts of their own species.Mention of a proprietary product does not constitute an endorsement by the USDA.     

Factors Influencing the Adhesion of Microorganisms to Surfaces

Starvation, growth phase, and carbon source influenced bacterial cell surface hydrophobicity. Both the number and kind of microorganisms that colonized metal surfaces depended on the type of metal and the presence of an imposed electrical potential. No significant differences in attachment and growth of a pure culture were observed when metal surfaces were dipped in an exogenous energy source. The chemical composition of naturally occurring adsorbed organic films on metal surfaces was shown to be independent of surface composition and polarization.     

SCRUBBING OF NITROGEN OXIDES WITH NITRIC ACID SOLUTIONS

A mathematical model is developed for an equilibrium stage analysis of nitrogen oxides absorption in nitric acid solutions. Using equilibrium data available from the literature, the model demonstrates that 15-35 wt% nitric acid may be efficiently used to reduce pollutant emissions in NO_x-containing gases having low degree of oxidation. Lower oxides of nitrogen accumulate in the liquid as nitrous acid which is carried away by the nitric acid solution. The scrubbed gas contains a reduced concentration of nitrogen oxides and has a higher degree of oxidation than the feed gas.     

Effects of three phenolic acids on chlorophyll content and growth of soybean and grain sorghum seedlings

Experiments were designed to test the hypothesis that interference with chlorophyll metabolism may be one mechanism of inhibition of plant growth in allelopathic interactions. Effects of ferulic,p-coumaric, and vanillic acids on soybean and grain sorghum growth and chlorophyll content were quantified and compared after seedlings were treated with these compounds in a nutrient culture. Following a 6-day treatment cycle, dry weights of soybean seedlings were reduced by both 10^–3 M and 5 × 10^–4 M treatments of ferulic,p-coumaric and vanillic acids. Soybean weight reductions in each case were paralleled by a significant reduction in the concentration (g Chl/mg dry wt) of chlorophylls a and b and total chlorophyll in the unifoliate leaves. Sorghum seedling growth was also reduced by each of the compounds at the 5 × 10^–4 M level, but leaf chlorophyll concentration was not below that of control plants.     

Preparation and performance of poly(lactic acid)/amidated ammonium citrate intercalated saponite nanocomposites

ABSTRACT

In this article, a novel method, amidation, was used to modify saponite. Amidated ammonium citrate intercalated saponite (Aa-saponite) was synthesized by amidation reaction. The structure of Aa-saponite was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), demonstrating that the saponite was successfully amidated. Polylactic acid/amidated ammonium citrate intercalated saponite nanocomposites (PLA/Aa-saponite) were prepared by melt blending. Mechanical tests demonstrated that the addition of Aa-saponite (0.3 wt%) improved the impact strength of PLA. A series of performance analysis results showed that A-saponite improved the comprehensive performance of PLA, such as mechanical, thermal stability, crystallization and rheological properties.