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141.
A vinyl monomer having an electron-donating moiety, p-(N,N-dimethylamino)styrenc (DMAS),was synthesized. It was combined with benzoyl peroxide (BPO) to form a redox initiation system to initiatethe polymerization of methyl methacrylate (MMA). UV spectra measurements show that DMAS enters thePMMA chain as well. Both DMAS and its polymer P(DMAS) display strong fluorescence, and thefluorescence can be quenched by electron-deficient compounds such as methacrylonitrile, fumaronitrile andmethyl methacrylate etc. Moreover, DMAS can also form charge transfer complex (CTC) with strongelectron acceptors such as tetracyanoethylene (TCNE). The difference between the photochemical propertiesof DMAS and P(DMAS) were explained in terms of molecular structure change and polymer conformationeffect in solution. In addition, the CTC and exciplex formation of DMAS or P(DMAS) with C_(60) were alsostudied. 相似文献
142.
A capillary electrophoresis (CE) method was developed for the separation of heparin oligosaccharides compatible to study the interactions between the oligosaccharides and granulocyte-colony stimulating factor (G-CSF). Unfractionated heparin was eliminitively degraded to heparin oligosaccharides by an endolytic heparinase. The degraded smaller oligosaccharides (M(r) < 1000) were baseline-separated by CE under a 50 mM phosphate buffer (pH 9.0) in 10 min. Standard heparin disaccharides and larger oligosaccharides (1000 < M(r) < 8000) were all separated under optimized separation conditions. Compared with standard heparin disaccharides, smaller oligosaccharides contained one nonsulfated, two monosulfated, and two disulfated disaccharides, but trisulfated disaccharides were not found. The smaller oligosaccharides were also identified and molecular mass was deduced by electrospray ionization-mass spectrometry (ESI-MS). Furthermore, interactions between G-CSF and the oligosaccharides were studied by using capillary zone electrophoresis (CZE) under the above separation conditions. It was found that larger oligosaccharides could interact with G-CSF while smaller oligosaccharides were not observed to bind to G-CSF under the experimental conditions. In conclusion, the purified heparinase could selectively degrade heparin into oligosaccharides and the interaction between G-CSF and heparin was correlated with the chain length of heparin. 相似文献
143.
Microporous activated carbons prepared from palm shell by thermal activation and their application to sulfur dioxide adsorption 总被引:2,自引:0,他引:2
Textural characterization of activated carbons prepared from palm shell by thermal activation with carbon dioxide (CO(2)) gas is reported in this paper. Palm shell (endocarp) is an abundant agricultural solid waste from palm-oil processing mills in many tropical countries such as Malaysia, Indonesia, and Thailand. The effects of activation temperature on the textural properties of the palm-shell activated carbons, namely specific surface area (BET method), porosity, and microporosity, were investigated. The activated carbons prepared from palm shell possessed well-developed porosity, predominantly microporosity, leading to potential applications in gas-phase adsorption for air pollution control. Static and dynamic adsorption tests for sulfur dioxide (SO(2)), a common gaseous pollutant, were carried out in a thermogravimetric analyzer and a packed column configuration respectively. The effects of adsorption temperature, adsorbate inlet concentration, and adsorbate superficial velocity on the adsorptive performance of the prepared activated carbons were studied. The palm-shell activated carbon was found to have substantial capability for the adsorption of SO(2), comparable to those of some commercial products and an adsorbent derived from another biomass. 相似文献
144.
A series of poly(ethylene glycol) biscoumarinyloxyacetatea have been synthesized and their intramolecular photochemical cyclodimerizations have been studied. It was found that only syn-HT configuration products were obtained when these bisesters were directly irradiated in chloroform, and the yields of the products decreased with the increase of the chain length. This photocyclization reaction is a convenient and effective method to synthesize macrocyclic compounds. 相似文献
145.
Adam Bange Jian Tu Xiaoshan Zhu Chong Ahn H. Brian Halsall William R. Heineman 《Electroanalysis》2007,19(21):2202-2207
A microbead based sandwich immunoassay for MS2 bacteriophage was developed using an interdigitated array (IDA) electrode with nanoscale dimensions (220 nm electrode width, 620 nm gap). The IDA was fabricated using an electron beam lithographic lift‐off technique. After an antibody‐assisted capture of MS2 using paramagnetic microbeads, a β‐galactosidase labeled secondary antibody was used to convert p‐aminophenyl‐β‐D ‐galactopyranoside (PAPG) into the redox active p‐aminophenol (PAP). Amperometric detection of PAP with IDA electrodes at +300 and ?200 mV vs. a Ag/AgCl reference electrode was used to measure the result, detecting MS2 concentrations as low as 10 ng/mL. 相似文献
146.
Cheung E Chong KC Jayaraman S Ramamurthy V Scheffer JR Trotter J 《Organic letters》2000,2(18):2801-2804
[reaction: see text] Four methods of asymmetric induction in the cis, trans-photoisomerization of 2beta, 3beta-diphenylcyclopropane-1alpha-carboxylic acid derivatives were studied. Best results (ca. 80% de) were obtained by irradiation of chiral esters, amides, and salts in NaY and LiY zeolites and in the pure crystalline state. 相似文献
147.
金属离子掺杂对TiO2光催化性能的影响 总被引:14,自引:1,他引:14
TiO2光催化反应过程涉及光生电荷、电荷迁移、电荷在TiO2表面的反应和溶液体相反应4个顺序相接并相互影响的步骤.在TiO2中掺杂金属离子对以上4个步骤均有重要影响,合理的掺杂可有效地提高其光催化性能.本文综合了国内外此方面的最新研究成果,从提高TiO2光催化性能和优化光催化反应的角度出发,在材料吸光能力、电荷扩散、表面反应、粒径和晶型等方面,全面地分析总结了金属离子掺杂的影响效果和规律性认识,并对TiO2基光催化材料的金属离子掺杂改性研究的未来发展方向提出了建议.文中还简要介绍了相关的掺杂方法和材料表征手段. 相似文献
148.
BEHAVIOR OF SUPPORTED NANO-COPPER CATALYST IN CO OXIDATION 总被引:1,自引:0,他引:1
IntroductionNanomaterialisanewkindofmaterialwithparticlesizebetWeenIurnand100urn.Becauseofthesmallparticlesizeandthelargespecificsufficearea,nanomaterialpossessesmanyparticularproperties,suchashighersufficeenergyandhighersurfaceactivity.t.[l]Thehigheracti… 相似文献
149.
Perišić-Janjić Nada U. Ž. Jovanović Bratislav Janjić Natasa J. Rajković Olga S. Antonović Dušan G. 《平面色谱法杂志一现代薄层色谱法》2003,16(6):425-432
JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of nine newly synthesized s-tri-azines has been studied by thin-layer chromatography on C18/UV254... 相似文献
150.
物理有机化学是现代有机化学的主要理论基础,是当今有机化学中最富有活力的领域之一,它是建立在现代物理学和物理化学的基础上,用物理化学的、定量的、数学的方法来研究有机化学. 相似文献