二茂钛含氟有机酸衍生物的质谱研究

本文研究了二茂钛含氟长链有机酸衍生物(1～3)和具有环状结构的新型二茂钛全氟有机酸(4～7)的电子轰击质谱(EIMS)和负离子化学电离质谱(NICIMS)。在EI谱中出现弱的或不出现M~+,1～7均以CpTiF_2离子为基峰。高质量区的主要特征碎片离子有[M-·cp]~+、[M-R]~+(1～3)和氟重排离子。在低质量区出现一系列二茂钛及茂钛氟重排离子。 1、4～7的NICI(CH_4)质谱中,4、5出现强的M~-离子峰,1出现[M-1]-离子峰,有两个钛的环状结构化合物6和7出现双电荷M~=离子峰,而不出现M~-。     

Biosensors for environmental pollutants and food contaminants

This review article provides an overview of the most recent literature on biosensors for environmental pollutants and food contaminants. Due to the large number of publications, only papers published between 2000 and January 2003 were considered. Also, while not all of the published literature could be reviewed here, over 200 references are cited to provide a good overview of research undertaken in the last two years. Older publications are covered by a number of earlier review articles. This article provides an introduction into the field including specific consideration of the application areas, describes the typical biosensor assay format used, and is subsequently structured according to the biorecognition elements used (i.e., nucleic acids, enzymes, whole cells, tissue and whole organisms, antibodies and receptors, and biomimetic materials). In addition, a section on microbiosensing systems is provided. Since only very few microbiosensors with applications in environmental and food systems have been published, enabling technology is also covered in this article.Abbreviations BOD biological oxygen demand - cfu colony forming units - DNP dinitrophenol - GFP green fluorescent protein - NASBA nucleic acid sequence-based amplification - PCR polymerase chain reaction - ppt parts per trillion - QCM quartz crystal microbalance - SPR surface plasmon resonance     

The thermal reaction of HNCO at moderate temperatures

The thermal reaction of HNCO has been studied in a static cell at temperatures between 873 and 1220 K and a constant pressure of 800 torr under highly diluted conditions. The reaction was measurable above 1000 K by FTIR spectrometry. The products detected include CO, CO₂, HCN, NH₃, and the unreacted HNCO. In this moderate temperature regime, the rates of product formation and HNCO decay cannot be accounted for by a previously established high-temperature mechanism, assuming HNCO → NH + CO (1) as the initiation process. Instead, a new bimolecular reaction, 2HNCO → CO₂ + HNCNH (2), has been invoked to interpret the disappearance of HNCO as well as the formation of various products, most importantly CO₂. The concentration profiles of all measured species can be quantitatively modeled, throughout the temperature range analyzed, by varying k₂ using a modified mechanism. The kinetically modeled values of k₂ can be effectively represented by This result agrees closely with that computed with the conventional transition-state theory using the TST parameters predicted by the BAC-MP4 method: The bimolecular reaction takes place via a stable 4-membered ring intermediate which is isoelectronic with diketene; viz.      

聚合物分子链的横截面积与分子链的运动

本文把单个分子链的横截面积与聚合物的玻璃化转变温度联系起来,发现对于所讨论的聚合物,考虑了分子链间的相互作用以后,上面二者之间有一一对应的关系。认为单个分子链的横截面积与聚合物分子链柔顺性有关。同时采用文献[17]的方法,得到了1,2-聚丁二烯的分子链的内旋转异构化能,比较所得结果,证实了上面的看法。     

Synthesis of a novel 18β-glycyrrhetinic acid derivative

A novel compound, biotinylated 18β-glycyrrhetinic acid (BGA), was synthesized. It is a compound of 18β-glycyrrhetinic acid linked with biotin. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 266–267, May–June, 2006. An erratum to this article is available at .     

Photoinduced deformation of amphiphilic azo polymer colloidal spheres

Photoinduced shape deformation of colloidal spheres made of an amphiphilic azo polymer has been demonstrated in this work. The polymer contains the donor-and-acceptor-type azobenzene chromophores and can form uniform colloidal spheres by dropwise adding water into its THF solution. When the colloidal spheres obtained were exposed to the interfering p-polarized Ar+ laser beams (150 mW/cm2), the colloidal spheres changed to prolates (i.e., "rugby-balls"), "spindles", and finally "rods", depending on the irradiation times. The elongated direction of the spheres was observed to be the same as the polarization direction of the laser beam. The average major-to-minor ratio of the ellipsoids could be easily adjusted by controlling the irradiation time. The deformation effect observed in this work can offer a new way to prepare nonspherical colloids from colloidal spheres and will shed new light on the correlation between the photodriven shape deformation and photoinduced surface relief gratings for the same type of polymers.     

A kinetic approach to homogeneous Ziegler type polymerization. Steady state

In this paper we present a kinetic approach to the analysis of steady-state homogeneous Ziegler-Natta polymerization activity data. The influence of the number of monomeric species that are coordinated to the active site on the apparent rate law is discussed and the equations are fitted to the experimental results.     

Determination of uranium by XRF analysis following its preconcentration with some organic precipitants

The determination of uranium in natural waters by XRF analysis after its preconcentration with some organic precipitants is described.¹⁰⁹Cd source is used for the excitation of L-series X-rays of uranium. Separation yield, kinetics of coprecipitation and the possibility of preparing thin-layer samples for XRF analysis were studied in detail for uranium concentration with α-nitroso-β-naphtol, methylene blue with ammonium thiocyanate, tannin with urotropine and other precipitants. A procedure using coprecipitation of uranium with α-nitroso-β-naphtol from 500 ml samples of surface or waste, waters is proposed.     

Effects of <Emphasis Type="Italic">L</Emphasis>-Carnitine on Sucrose-Induced Hyperlipidaemia

Summary. L-Carnitine, L-(−)-β-hydroxy-γ-trimethylaminobutyrate, plays an important role as a factor necessary for the transport of long-chain fatty acids into the mitochondria. In order to investigate the influence of L-carnitine on hyperlipidaemias, the experimental model of the sucrose-induced hypertriglyceridaemia of the rat was used. In these experiments L-carnitine in the dose of 11 mg per day and 100 g body weight (over the period of 1 week) was able to antagonize the sucrose-induced hypertriglyceridaemia and the increase of serum free fatty acid level in female rats of the Wistar strain. Carnitine administration did not change the activities of lipogenic enzymes and fatty acid synthesis in the liver. However, L-carnitine increases the rate of hepatic fatty acid oxidation. Our results indicate a hypotriglyceridemic and free fatty acid lowering effect of L-carnitine, and suggest the use of this compound in the therapy of hyperlipidaemias.     

Inclusion and fractionated release of nucleic acids using microcapsules made from plant cells.

The encapsulation and fractionated release of nucleic acids on vesicular packing (VP) materials have been investigated. The earlier described dependence of the permeation of nucleic acid molecules through the vesicle membranes on the salt concentration is a necessary precondition for both encapsulation and fractionation. Encapsulation is achieved by applying a suitable sample onto a VP column that has been equilibrated with a high-salt buffer. In that buffer the sample molecules are permeable. Immediately after sample application, elution is started with a low-salt buffer, from which the sample molecules are excluded. At the front between the two buffers the permeability changes, and some of the sample molecules distributed inside the vesicles cannot pass through the membranes. These encapsulated molecules can be released by increasing the salt concentration in the eluent. If the encapsulated nucleic acid sample is polydisperse, a stepwise or linear increase in the salt concentration leads to a fractionated release. The fractions obtained differ in their molecular size composition.