2,6-二氯靛酚钠动力学分光光度法测定西红柿及草莓中的抗坏血酸

本文提出用2，6－二氯靛酚纳（以下简写DIS）作氧化剂动力学分光光度测定L－抗坏血酸的新方法。DIS与L－抗坏血酸混合．在固定时间间隔于611nm处测得吸光度A值的变化（△A／△t）与抗坏血酸含量成线性关系。线性范围为0～12mg／L。在样品处理时采用偏磷酸作为提取剂，以减缓抗坏血酸被氧化的速度结果表明，该方法有较高灵敏度，且操作简便，试剂易得，容易推广，是测定水果和蔬菜中L-抗坏血酸的好方法。     

High-productivity continuous biofilm reactor for butanol production

Corn steep liquor (CSL), a byproduct of the corn wet-milling process, was used in an immobilized cell continuous biofilm reactor to replace the expensive P2 medium ingredients. The use of CSL resulted in the production of 6.29 g/L of total acetone-butanol-ethanol (ABE) as compared with 6.86 g/L in a control experiment. These studies were performed at a dilution rate of 0.32 h⁻¹. The productivities in the control and CSL experiment were 2.19 and 2.01 g/(L·h), respectively. Although the use of CSL resulted in a 10% decrease in productivity, it is viewed that its application would be economical compared to P2 medium. Hence, CSL may be used to replace the P2 medium. It was also demonstrated that inclusion of butyrate into the feed was beneficial to the butanol fermentation. A control experiment produced 4.77 g/L of total ABE, and the experiment with supplemented sodium butyrate produced 5.70 g/L of total ABE. The butanol concentration increased from 3.14 to 4.04 g/L. Inclusion of acetate in the feed medium of the immobilized cell biofilm reactor was not found to be beneficial for the ABE fermentation, as reported for the batch ABE fermentation. Names are necessary to report factually on available data. However, the USDA neither guarantees nor warrants the standard of the product, and the use of the names by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Effect of sodium dodecyl sulfate on lipase ofCandida lipolytica

The effects of sodium dodecyl sulfate on extracellular lipase produced byCandida lipolytica have been studied. The microorganism was grown in culture medium containing different sodium dodecyl sulfate concentrations added to the culture at different intervals of growth. The extracellular lipase activity was not detected when the treated culture supernatants were directly tested in Yeast Mold Agar-Triolein-Rhodamine plates, regardless of surfactant addition time and concentrations. However, after ammonium sulfate precipitation and dialysis, the extracellular lipase activity could be recovered. Therefore, the surfactant, under the experimental conditions used here, does not seem to be able to inhibit lipase production, but it does inhibit the enzyme activity because of its presence in the mixture of the reaction.     

Unusual features of micellar diffusion

Diffusion coefficients of tetradecyltrimethylammonium bromide in aqueous solutions have been determined at 25, 95 and 135 °C using the Taylor dispersion technique. The diffusion coefficient exhibits a minimum at a surfactant concentration above the critical micelle concentration (CMC). The results are interpreted in terms of electrostatic coupling and rapid exchange between micelle, surfactant monomer and counterions.     

螯合树脂交换——光度法测定氯化钠溶液中微量镁

研究了用螯合树脂交换分离富集氯化钠溶液中微量镁及吸光光度法测定镁含量的方法。回收率为９６．０－１０１．０％，在ＰＨ１０的硼砂－氢氧化钠介质中，镁含量在０－１２μｇ／２５ｍｌ范围内符合比耳定律。方法稳定性高、重现性好。     

Variation of the ℏω with the particle number and the appearance of “kinks” for atomic clusters

The dependence of the harmonic oscillator (HO) energy level spacing ?ω on the particle number N is studied analytically for atomic (metal) clusters on the basis of their electronic densities, parametrizing Ekardt's results (for sodium clusters) by means of a Fermi distribution. An interesting feature of such an approach is that it leads, under the assumptions made, to “kinks,” that is, to “marked discontinuities in the slope” of ?ω at the closed shells. These discontinuities diminish as N increases. For large N, ?ω becomes simply: ?ω?c₁N^?1/3+c₂N^?1. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

硼氢化钠还原法合成1-(2,4-二氯苯基)-2-氯-乙醇

研究了硼氢化钠还原2,2',4'-三氯苯乙酮制备1-(2,4-二氯苯基)-2-氯-乙醇的两种方法. 考察了温度对反应的影响, 对目标产物和副产物的生成机理进行了探讨. 加入氯化钙、氯化镧等金属氯化物能有效促进反应的专一性, 并对其作用机理进行了探讨. 在非质子溶剂如THF中有阳离子树脂的存在下, 还原反应平稳, 具有高产率和高选择性. 对目标产物进行了结构表征.     

均匀棒状过氧化氢合碳酸钠制备及非等温热分解动力学

本文制备了均匀棒状过氧化氢合碳酸钠，化学分析确定其组成为Na₂CO₃·1.5H₂O₂，用DTA-TG-DTG技术并辅以X-ray分析研究了它在静态空气、流动氧气和流动氮气气氛中的非等温热分解过程及动力学。     

Synthesis and Structural Characterization of a Polyoxomolybdate HNa_7[Mo_(36)O_(112)(H_2O)_(16)]·47H_2O

A new polyoxomolybdate complex HNa7[Mo36O112(H2O)16]·47H2O 1 has been prepared in the beaker solution and characterized by single-crystal X-ray diffraction and elemental analyses. Crystal data: H127Mo36Na7O175, Mr = 6542.79, monoclinic, C2/c, a = 40.891(6), b = 17.900(3), c = 25.580(4) , β = 125.673(2)°, V = 15210(4) 3, Z = 4, Dc = 2.857 g/cm3, F(000) = 12464, μ = 3.013 mm-1, R = 0.0633 and wR = 0.1654 (I > 2σ(I)). With the bridging sodium cations, the [Mo36O112(H2O)16]8- units in compound 1 are linked to form a one-dimensional structure, on the basis of which a three-dimensional architecture is further constructed via other sodium cations and complicated hydrogen bonds.     

多氟烷基取代的环丙烷衍生物的合成

以连二亚硫酸钠为引发剂, 烯丙基丙二酸二乙酯与多氟烷基碘代烷在温和反应条件下反应, 方便地得到一系列多氟烷基取代的环丙烷衍生物, 产率45%～55%. 在相同条件下, 烯丙基乙酰乙酸乙酯与多氟烷基碘代烷反应得到相应的加成物, 加成物随后用碱处理也得到环合的产物.