近临界水中薯蓣皂苷水解生成薯蓣皂苷元的工艺研究

薯蓣皂苷元是合成甾体激素类药物和甾体避孕药的重要中间体,传统工艺采用盐酸水解法将黄姜中的薯蓣皂苷水解生成薯蓣皂苷元,反应时间4 h,最大收率为1.78%.该工艺反应时间长,耗水量大,对环境污染严重.今研究了无催化剂条件下,近临界水中薯蓣皂苷水解成薯蓣皂苷元的工艺,分别考察了反应温度、反应压力、反应时间等因素对薯蓣皂苷元收率的影响.研究结果表明,近临界水解法工艺简单,反应时间短,对环境友好,在较佳工艺条件下:P=25.0 MPa,T=260℃,t=10 min,薯蓣皂苷元收率为1.46%.     

Hydrolytic decomposition of dichlorodifluoromethane on modified zirconium oxide surfaces

The hydrolytic decomposition of dichlorodifluoromethane (CFC-12) on various modified zirconium oxide surfaces has been studied. The reaction was carried out under flow conditions at 500°C. Complete CFC-12 conversion and long-time stability of the catalysts were achieved accompanied by a limitation of the undesired CFC-13 formation. A maximum CFC-12 conversion was observed on catalysts of sulfated zirconia or zirconia obtained from temperature-controlled calcination of zirconium oxide hydrate. The reaction depends on the presence or in situ formation of Brønsted acid sites. FTIR-photoacoustic measurements were performed on pyridine complexes chemisorbed on the catalyst surface in order to analyze the changes in the catalyst's acidity. The effects of the temperature and water in the reaction gas on the catalyzed decomposition of CFC-12 are examined.     

Hydrolysis of human horny cells by alkaline protease: Morphological observation of the process

The interaction of highly purified alkaline protease fromBacillus sp. KSM-K16 with the horny cells of human skin contained in skin grime was directly visualized by electron microscopy. It became clear that the protease first penetrates the horny cells and then adsorbs, mainly onto the internal structure of the cells at the initial stage of hydrolysis, and directly hydrolyzes the keratin filaments, though the marginal band surrounding them retains its original shape. Then, hydrolysate produced from the keratin filaments flows out of the cell, and early in the hydrolysis process keratin filaments decrease and then disappear, leaving a marginal band, i.e., the cell turns to a hollow state. As a result, the remaining marginal band loses support from inside the cell, thus promoting cleavage and dispersion. Until this stage in the protease reaction, the remarkable liberation of hydrolysis products as water-soluble protein does not occur.     

液相水解法合成金红石型TiO2

提出的钛液反应水解法，改变了传统的外加晶种存在下具有工业意义的水解过程。该法无须外加晶种，选择了以酒石酸，聚丙烯酰胺为沉淀剂，絮凝剂，在常压下使钛液直接长温水解，液相共沉淀制备金红石型ＴｉＯ２。还研究了反应条件，分析了产品的特性。     

CONCENTRATED ACID CONVERSION OF PINE SOFTWOOD TO SUGARS. PART I: USE OF A TWIN-SCREW REACTOR FOR HYDROLYSIS PRETREATMENT

The first stage of a two-step concentrated sulfuric acid process that converts softwood sawdust to sugars has been explored. The research focuses on the ability of an in-house custom fabricated corotating twin-screw reactor (TSR) to effectively break down and solubilize crystalline cellulose into low molecular weight carbohydrates. Based on design of experiment (DOE) screening results, a four-level, two-factor experimental model building DOE was undertaken. Solid sawdust conversion to liquid, screw torque, and TSR exit pressure were measured or recorded at each experimental condition to yield percent conversion of solids, processed material viscosity, and material energy requirements. Thereafter, model quadratic equations were fitted to the experimental data and found to be statistically significant. Based on data obtained in the DOE the process was optimized to establish a base case operating condition. The acid-treated product made at base case twin-screw operating conditions showed a 38.2% conversion of dry sawdust solids to soluble liquids. The dry solids conversion reduced 73.8% of all hemicellulose and 44.4% of all cellulose to soluble monomers and oligosaccharides.     

Chemical interactions between soil N and alkaline-hydrolysing N fertilizers

Chemical interactions between soil N and alkaline-hydrolysing N fertilizers labelled with¹⁵N were studied in the laboratory using twelve-irradiated soils. Fertilizer was recovered in the soil organic N fraction via the process of NH₃ fixation. NH₃ fixation at day 7 varied from 1.8 to 4.6% of the N added as aqua ammonia at 1000 mg kg^–1 soil. The amount of NH₃ fixed increased with increasing rates of application of NH_3(aq) and urea. The rate of NH₃ fixation decreased with time, with more than 55% of the total NH₃ fixation in 28 days occurring in the first week following application of 2000 mg urea-N kg^–1 soil. Soil pH and NH₃ fixation varied in response to N source, and increased in the order of di-ammonium phosphate 3 fixation, resulting in the release of unlabelled ammonium (deamination) and a real added nitrogen interaction in all but two of the soils studied. The release of NH ₄ ⁺ initially increased up to a pH of 7.5, was inhibited between pH 8.5 and 9.0, but increased thereafter. The balance (N_bal) between NH₃ fixation and deamination was either positive or negative, depending on the pH of the fertilized soil, which was directly related to N source and concentration for a given soil.     

水解酸化-SBR法处理生物制药废水

对采用水解酸化-SBR法处理生物制药废水的调试运行作了详细说明。工程实践表明，该工艺对处理有机物浓度高、水质水量波动大的生物制药废水是切实可行的，出水水质可达到国家污水综合排放标准一级标准．剩余污泥也得到有效处理处置。该工艺结构简单，操作简便，占地面积小，运行效果稳定，具有推广应用价值。     

Kinetics of the peracetic acid decomposition: Part II: pH effect and alkaline hydrolysis

The effect of pH on the decomposition of peracetic acid in an aqueous solution was studied. It was found that three potential reactions, namely i) the spontaneous decomposition, ii) the hydrolysis and iii) the transition metal catalysed decomposition, are responsible for the consumption of peracetic acid. The spontaneous decomposition reaches its maximum at pH 8.2, while both the hydrolysis and metal ion catalysed decomposition increase as the pH increases. At pH 10.5 and higher, the hydrolysis becomes dominant when the metal ion catalysed decomposition is minimized by the addition of DTMPA. The kinetics of the peracetic acid hydrolysis was developed, which can very well predict the development of peracetic acid and hydrogen peroxide during the decomposition reaction.     

Mechanical Activation of Tetracalcium Phosphate

It was found that prolonged high-energy ball-milling of Hilgenstokite (tetracalcium phosphate, TTCP) resulted in a decrease in both particle and crystallite size, leading to a mechanical activation of the compound. This mechanically activated material demonstrated a high reactivity such that, in contrast to highly crystalline TTCP, a setting reaction with water to nanocrystalline hydroxyapatite (HA) and Ca(OH)₂ could be achieved at 37°C. However, crystalline TTCP is practically unreactive at physiologic temperatures because of the formation of a thin HA layer on the particle surface preventing further reaction.     

酶/酸水解毛叶木姜子中键合态香味成分的比较

采用AmberliteXAD-2树脂吸附洗脱分离毛叶木姜子中的键合态香气物质前体,将分离得到的键合态香气物质前体在AR2000酶、果胶酶和酸3种条件下分别进行水解释放,采用气相色谱-质谱联用法(GC-MS)对水解后的键合态香气物质进行分离分析。结果表明:3种水解条件得到的键合态香气物质共有90种,主要为萜烯类和含氧萜类物质。其中,香叶醇在2种酶水解条件下均含量高,果胶酶水解条件下含量最高达21798.79μg/L;共34种香气物质具有明显香气特征,2种酶水解下最显著的香气特征为花香和甜香;酸水解条件下最显著的香气特征为花香。酶水解与酸水解条件下得到的键合态香气物质存在明显差异,果胶酶水解条件下所检出的香气物质种类多且含量较高。因此,果胶酶处理更有利于毛叶木姜子键合态香气成分的释放。