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71.
V. G. Berezkin A. A. Korolev I. V. Malyukova R. G. Mardanov 《Russian Chemical Bulletin》1997,46(12):2064-2073
The effects of the carrier gas nature and pressure on the relative retention values of organic compounds were studied using
a series of capillary columns differing in the film thickness of the polar stationary phase (PEG-20M). Relative retention
depends linearly on the carrier gas pressure. This dependence becomes more pronounced in the following order of carrier gases:
helium < nitrogen < carbon dioxide. The limiting relative retention at a carrier gas pressure approaching zero rather than
relative retention values measured experimentally (relative retention time, Kovats retention index,etc.) is an invariant characteristic of a compound subjected to chromatography. For the carrier gases studied, the limiting retention
values almost does not depend on the nature of the carrier gas used. The limiting indicating the complex absorption-adsorption
nature of these parameters. Dissolution of a carrier gas in the stationary liquid phase has an effect on the relative retention.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2177–2186, December, 1997. 相似文献
73.
乳状液膜法提取L-谷氨酸的研究徐占林(四平师范学院化学系四平136000)严忠张河哲(东北师范大学化学系长春130024)关键词L-谷氨酸乳状液膜载体萃取中图分类号O623.736氨基酸作为重要的生化产品,广泛应用于食品、饲料、医药、化工等许多领域,... 相似文献
74.
Suyao?Xiao Xuanming?LiuEmail author Chunyi?Tong Jun?Liu Dongying?Tang Lijian?Zhao 《中国科学B辑(英文版)》2005,48(2):162-166
Anion starch nanoparticle (StNP) with a diameter of 50 nm was prepared in water-in-oil microemulsion, with soluble starch
as raw materials and POCl3 as crosslinking agent. PLL-StNP was prepared by linking poly-L-lysine (PLL) on the surface of StNP. At the same time, the
size of PLL-StNP and its stability in aqueous solution were checked by AFM. The analysis of plasmid DNA binding, DNase I enzymatic
degradation, toxicity and transfection were done. We discovered that PLL-StNP may be used as non-virus nanoparticle gene carrier.
And we developed the method of preparing PLL-StNP gene carrier and used it in cell transfection. As non-virus gene carrier,
PLL-StNP has some advantages, such as large load of DNA, high transfection efficiency, low cell toxicity and biodegradability. 相似文献
75.
溶剂聚合膜pH电极作内电极的气敏电极的研究 总被引:1,自引:0,他引:1
研究了以中性载体为活性物的石墨内导平头溶剂聚合膜(SPM)pH电极作内电极的二氧化碳和氨气敏电极。电极的性能取决于中性载体的特性,其中以菸酸十八酯为内电极膜活性物的二氧化碳气敏电极和以二辛基十八胺为活性物的氨气敏电极性能较佳。二氧化碳气敏电极用作丙酮酸脱羧酶酶电极的原电极,其性能院于传统的以玻璃pH电极作内电极的二氧化碳气敏电极。 相似文献
76.
A starter culture ofTrichoderma reesei (Rut-C30) prepared in a liquid fluidized bed reactor (LFBR) gave better growth and greater cellulase production in submerged
fermentation than a conventional shake flask inoculum. The LFBR starter was prepared by first coatingT. reesei spores to 0.25 mm size corncob (1.0x108g-1) in a medium containing 1.0% corncob, 0.5 gL-1 xylose and 0.1 gL-1 lactose in a balanced salt solution, then fluidizing the particles in the LFBR for 36 h to allow germination of the spores,
and covering the particles with an approx 30 μm thick biofilm. This biofilm that developed in constant adherence to the lignocellulosic
carrier, apparently became well adapted to grow rapidly on insoluble cellulose substrates (Solca Floc), and had the enzymes
of the cellulase complex induced for increased cellulase production.
The LFBR starter used in a stirred tank reactor (STR) gave 15 gL-1 biomass production and 6.5 IU mL-1 overall cellulase activity with a volumetric productivity of 64 IU L-1h-1 in a 5 d fermentation, compared with a 7 d shake flask inoculum that gave 11 gL-1 biomass and 3.2 IU mL-1 cellulase activity, with a volumetric productivity of 31IU L-1h-1. The LFBR starter culture retained its viability in dry storage for 6–9 mo. 相似文献
77.
Keiichi Kimura Masayuki Kaneshige Hideo Tokuhisa Masaaki Yokoyama 《Journal of polymer science. Part A, Polymer chemistry》1993,31(11):2809-2813
Copolymers of bis[4-(N,N-dimethylamino)phenyl]-4-vinylphenylmethanenitrile (vinyl Malachite Green leuconitrile) with methyl methacrylate or ω-methoxyoligo(oxyethylene) methacrylate have been synthesized, aiming at designing one-component-type organic polymers for photoswitchable ion-conducting films. The triphenylmethanenitrile copolymers with ω-methoxyoligo(oxyethylene) methacrylate were found to undergo ionic-conductivity switching by turning on and off UV light at ambient temperature, owing to their low glass transition temperature. © 1993 John Wiley & Sons, Inc. 相似文献
78.
We report a nanoscale lipid membrane-based sensor of conjugated polydiacetylene (PDA) vesicles for fluorescence detection of organic amines. The vesicle sensor was constructed by incorporation of a BODIPY fluorescent dye into the PDA vesicles. The fluorescent properties of the resulting vesicles can be manipulated by adjusting lipid components, and are controlled by environmental and solution conditions. The fluorescence of the BODIPY dye was significantly quenched in the polymerization of diacetylene lipid vesicles by a UV irradiation process. However, it was sufficiently recovered by external stimuli such as a hike of solution pH. The fluorescence recovery process was reversible, and a decrease in solution pH resulted in repeated quenching. The reported system transforms an external stimulus into a large fluorescence intensity change, demonstrating great potential in developing new signal reporting method for biosensor design. The quench-recovery phenomenon of the BODIPY-PDA is believed to be related to the energy transfer between the dye and the PDA conjugate backbone. The vesicle sensor was applied for detecting an organic amine, triethylamine (TEA) and a large linear relationship was obtained between the increase in fluorescence intensity and the concentrations of TEA. The detection limit of TEA by vesicle sensors using fluorescence recovery was found to be 10 μM. 相似文献
79.
80.
Three non-specific methods for the extraction of total petroleum hydrocarbons (TPH) from soil into organic solvent were compared.
The techniques used for sample preparation were Soxhlet extraction, closed-vessel microwave-assisted extraction, and CEN shake
extraction. The total concentrations of extracted compounds in the boiling point range of C10–C40 were determined by gas chromatography
with flame ionization detection. The best recovery (99%) and repeatability (±3%) from standard oil mixtures were obtained
with microwave-assisted extraction. However, the different extraction methods exhibited different behaviour when spiked soil
samples were extracted. The best repeatability was obtained with CEN shake extraction (±6%) but the repeatability values for
Soxhlet and microwave-assisted methods were quite high (>20%). However, the larger uncertainties of the latter extraction
methods does not necessarily limit the applicability of these methods to the determination of petroleum hydrocarbons in soil,
as in the assessment of soil contamination the expanded uncertainty of the result is usually not limited by analytical uncertainty,
but rather by the uncertainty of the primary sampling stage. However, distinctive variation found in the chromatographic profiles
illustrates that discretion should be obeyed when chromatograms obtained after application of different extraction methods
on petroleum contaminated samples are to be used in the fingerprinting or age dating studies. Otherwise, misleading conclusions
concerning the age of spillage could be drawn. 相似文献