环戊二烯热聚产物及二聚环戊二烯加氢产物的质谱

本实验用色谱－质谱－计算机联用仪测定了环戊二烯热聚产物及双环戊二烯加氢产物的质谱，讨论了环状化合物的开裂规律，有开环断裂反应及骨架重排等问题。     

Determination of Dopamine in the Presence of Ascorbic Acid on the IrO2-Ta2O5 Type DSA Electrode

IrO2Ta2O5 (70%: 30%, molar ratio) electrodes (ITEs) were prepared by the thermal decomposition method. Typical “mud-cracked” surface and surface enrichment of Ta were observed. The determination of dopamine (DA) was carried out in the presence of ascorbic acid (AA). The detection limit of DA was 5~10 5 mol/L without the interference of AA.     

Comparison of quantitative methods for analysis of polyphasic pharmaceuticals

Adequate very sensitive quantification methods are needed for the development and are also now required for the monitoring of undesirable solid form(s) as routine tests. The pre-requisite for quantitation are selectivity, sensitivity and most important the purity of standards and their proper storage, what is a challenge for metastable forms. Several analytical techniques are available such as X-ray diffraction, spectroscopy, thermal analysis and microcalorimetry. The different steps of the validation of the analytical methods and problems to be solved are discussed. Examples illustrate the different techniques and compare their possible advantages and limits. The relative standard deviation of measurements should allow for checking the homogenization procedure of mixtures for calibration. The validation should be carried out following ICH guidelines for validation of analytical methods. Comparison of different techniques in adequate concentration range add confidence in the analytical results.     

微波消解-氢化物发生原子荧光法测定塑料原料及其制品中的砷、汞

采用微波消解进行样品前处理，以硫脲为预还原剂，用氢化物发生原子荧光法测定塑料原料及其制品中的砷、汞。测定砷和汞的线性范围均为0～8μg／L，砷、汞的检出限分别为0．005、0．076μg／L，测定结果的相对标准偏差分别为4.96％～7．38％、2．94％～7．20％(n=6)，回收率分别为92．0％～103．2％、92．0％～98.0％。     

Temperature influence on hydrogen sorption in palladium limited-volume electrodes (Pd-LVE)

The effect of temperature on hydrogen and deuterium electrosorption into a palladium LVE (limited-volume electrode) has been investigated. A decrease in hydrogen capacity (H/Pd ratio) with increasing temperature has been observed. Temperature strongly influences the plots of measured H(D)/Pd values vs. potential scan rate. In addition, hydrogen absorption was found to be dependent on the composition of the surrounding electrolyte solution. These results have confirmed the hypothesis that two different mechanisms of hydrogen desorption from the palladium electrode take place, namely electrochemical oxidation and non-electrochemical recombination. Further, the ratio between the rate constants for these two processes has been found to change with temperature. Electronic Publication     

Kinetics of thermal decomposition of alkaline phosphates

Summary The thermal behavior of KH₂PO₄, NaH₂PO₄ and Na₂HPO₄ under non-isothermal conditions using TG method with different heating rates was studied. The values of the reaction rate were processed by means of Friedmans differential-isoconversional method. A dependence of the activation energy vs. conversion was observed. Therefore a procedure based on the compensation effect (suggested by Budrugeac and Segal) was applied. A less speculative data processing protocol was offered by the non-parametric kinetics method suggested by Serra, Nomen and Sempere. Three steps were observed by non-isothermal heating: a dehydration, a dimerization and a polycondensation. The differences in the intimate reaction mechanism are determined by the initial number of water molecules.     

Interaction of gas phase atomic hydrogen with Pt(111):Direct evidence for the formation of bulk hydrogen species

Employing hot tungsten filament to thermal dissociate molecular hydrogen,we generated gas phase atomic hydrogen under ultra-high vacuum(UHV)conditions and investigated its interaction with Pt(111) surface.Thermal desorption spectroscopy(TDS)results demonstrate that adsorption of molecular hy- drogen on Pt(111)forms surface Had species whereas adsorption of atomic hydrogen forms not only surface Had species but also bulk Had species.Bulk Had species is more thermal-unstable than surface Had species on Pt(111),suggesting that bulk Had species is more energetic.This kind of weakly- adsorbed bulk Had species might be the active hydrogen species in the Pt-catalyzed hydrogenation reactions.     

Preparation and partial characterization of a soluble site-to-site directed enzyme complex composed of alcohol dehydrogenase and lactate dehydrogenase

A soluble, bifunctional enzyme complex has been prepared by crosslinking lactate dehydrogenase and alcohol dehydrogenase with glutaraldehyde. The crosslinking was performed on a solid phase while the active sites of alcohol dehydrogenase and lactate dehydrogenase were held adjacent to one another with the aid of a bis-NAD analog. Subsequently, the enzyme complex was released from the solid phase. The soluble enzyme complex was then purified by using NAD-Sepharose as an affinity adsorbent. Based on gel filtration experiments, the complex was estimated to consist of one of each dehydrogenase. By using a third enzyme, lipoamide dehydrogenase, which competes with lactate dehydrogenase for NADH produced by alcohol dehydrogenase, the effect of site-to-site orientation was studied. It was found that about 83% of the NADH produced by alcohol dehydrogenase was oxidized by site-to-site oriented lactate dehydrogenase compared to a figure of only about 61% obtained in an identical system of separate enzymes. This indicates that given two alternative routes, the preference for the one to lactate dehydrogenase over the one to lipoamide dehydrogenase is enhanced when lactate dehydrogenase and alcohol dehydrogenase are site-to-site oriented.     

荧光法研究Ge—132对苯丙氨酸Maillard反应的抑制作用

哺乳动物体内氨基酸及蛋白质的非酶糖化反应（Ｍａｉｌａｒｄ反应）与糖尿病及其并发症的关系已引起广泛关注［１］，β－羧乙基锗倍半氧化物（Ｇｅ－１３２）具有预防糖尿病和调节糖代谢的作用［２］，研究Ｇｅ－１３２对Ｍａｉｌａｒｄ反应的抑制作用对于开发防治糖尿病...     

锂辉石—石灰石烧结中煤粉代替重油作燃料的研究和实践

目前世界锂工业原料以锂辉石为主。我国锂辉石储量居世界首位，主要分布于新疆、四川、湖南等地，其中又以四川的储量占全国第一。锂的主要基础化合物ＬｉＯＨＨ２Ｏ系用锂辉石－石灰石烧结法而得，烧结燃料是影响ＬｉＯＨＨ２Ｏ产品价格的重要因素之一。过去国内外均采用...