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991.
Polymer-dispersed liquid crystal (PDLC) films were prepared by photochemical polymerisation with a series of (meth)acrylate monomers. The effects of monomer structure on the morphology of polymer networks in the PDLC films were studied. The acrylate monomers without sidegroup chain formed uniform polymer networks. The methacrylate monomers with methyl as their sidegroup chains formed lace-like networks. The size of the LC droplets increased with increasing the length of the flexible chain of both methacrylate and acrylate monomers. Meanwhile, the effects of the morphology of the polymer network on the electro-optical properties of PDLC films were also investigated. 相似文献
992.
993.
Chia-Wen Lu Yan Cao Hui Li Cathleen Webb Wei-Ping Pan 《Journal of Thermal Analysis and Calorimetry》2014,116(3):1241-1248
Titanium dioxide (TiO2), especially in its anatase form, is an effective photocatalyst under ultraviolet (UV) light. The particle size of TiO2 is a critical factor to determine its photoactivity based on its quantum effectiveness under light irradiations. Thus, nanocrystalline TiO2 has been widely accepted to significantly enhance this effect. The sol–gel method is generally used to synthesize the anatase form of nanocrystalline TiO2. In this study, we expanded the synthesis method of TiO2 to high pressures under direct heating (hydrothermal method) and indirect heating (microwave-assisted method). It was found that pH value is one of the major factors to control nano-sizes of TiO2 particles, and the neutral condition in all methods is preferable for controlling the sizes of the prepared TiO2 particles. The microwave-assisted method further improves quality of synthesized nano-size TiO2 below 10 nm. These results have been confirmed by both the direct size measurement using TEM images and indirect determination using XRD peaks. The collected samples are further analyzed using UV–Vis spectroscopy to identify the particle size-dependent photoreactivity and to confirm the effectiveness of microwave-assisting under neutral conditions. DSC is also a powerful tool to identify the crystalline transition of TiO2. 相似文献
994.
995.
Luminescent silica nanocomposites functionalized with a Eu-complex have been prepared and characterized.The europium complex is composed of 2,2'-bipyridyl(BPy) and 2-(4-bromomethyI)-phenylpropionic acid(BMPPA),which contains highly active benzyl bromide substituents and can covalently bind with poly(4-vinylpyridine)(P4VP)-modified silica nanoparticles(nanoSiO_2P4VP) to form nanoSiO_2P4VPEuBPy composites.Microscopic images revealed that the nanoSiO_2P4VPEuBPy composites easily formed aggregates,due to an inter-particle binding caused by the benzyl bromide among the composites.The as-prepared nanocomposites showed the typical emissions of Eu(III) ions at the wavelengths from 580 nm to 750 nm designated to the ~5D_0→~7F_n transitions.Time-resolved fluorescence decay measurements revealed that the emission lifetime was approximately 0.204 ms and 0.576 ms for the nanoSiO_2EuBPy composites,a little shorter than that in the Eu(BMPPA)_3BPy complex. 相似文献
996.
Hang Ma Yang He Ruo-Feng Huang Xiao-Hui Zhang Jing Pan Jia-Qiang Li Chao He Xue-Ge Ling Xuan-Lun Wang Yan Xiong 《中国化学快报》2014,25(10):1327-1330
Under neat conditions,an efficient method for synthesis of imidoesters has been developed using cyanatobenzenes and dicarbonyl compounds.Nucleophilic addition spontaneously occurred between the two kinds of materials at room temperature with yields of up to 90%.A mechanism directed towards to the imidoester formation has been proposed. 相似文献
997.
The detailed reaction pathway and coke formation mechanism over Pt/metal oxide nanoparticles during the steam reforming of ethanol(SRE) at 300℃were studied.The catalysts were prepared by incipient wetness impregnation method and were characterized with CO pulse chemisorption, BET surface measurement,oxygen adsorption,ethanol-TPD,NH3-TPD,and TPO.The SRE activity of the catalysts with steam/ethanol molar ratio of 3/1 was tested using a continuous fixed-bed reactor.Strong interaction between Pt and supports causes lower H2 production temperatures and no C2H4 formation,while weak interaction leads to C2H4 formation and strong bonded CO on Pt particles during ethanol-TPD. H2 production over Pt-based catalysts is mainly resulted from the decomposition and dehydrogenation of ethanol,and decarbonylation of acetaldehyde.Meanwhile,coke can be formed from acetaldehyde,acetone,C2H4 and CO.However,when the interaction between Pt and supports is weak,more coke is formed especially from acetone,C2H4 and CO.When the interaction is strong,no coke formation is observed due to high oxygen storage capacity of the catalyst. 相似文献
998.
D. Shooter S. J. de Mora A. Grout D. J. Wylie He Zhi-yun 《International journal of environmental analytical chemistry》2013,93(4):239-249
Abstract A technique was developed using sparging and pre-concentration onto a Tenax trap at ambient temperature allowing field measurements to be made of reduced sulfur gases in Antarctic marine and glacial melt waters. Following thermal desorption, gases were determined by gas chromatography using a flame photometric detector. Detection limits in ng 1?1 were: H2S 50, OCS 8, SO2 160, CH3SH 6, CH3SCH3 20 and CS2 2. Storage of melt water samples for more than 24 hours resulted in concentration changes of the reduced sulfur gases present. While the Antarctic environment imposed limitations on the analytical method, an investigation of various pond and marine waters was undertaken. 相似文献
999.
Hui Sun Fangfang Wu Aihua Zhang Wenfeng Wei Ying Han Xijun Wang 《Biomedical chromatography : BMC》2013,27(11):1511-1519
Schisandra chinensis Baill grows wild in Russia, China, Korea and Japan, and its fruit has been found to be effective in amnesia and insomnia. It is enriched in schisandra lignans (SL) that are major components responsible for therapeutic action. However, there are no reports on the biotransformation analysis of SL. An ultra‐performance liquid chromatography/electrospray‐ionization high‐definition mass spectrometry (UPLC‐Q‐TOF‐HDMS) method was developed to investigate the metabolism of SL in vivo. MS was performed on a Waters Micromass high‐definition system with an electrospray ionization source in positive ion mode and automated MetaboLynx software analysis with excellent MS accuracy and enhanced MS data acquisition. An improved mass defect filter (MDF) method employing both drug and core structure filter templates was applied to the processing of UPLC‐Q‐TOF‐HDMS data for the detection and structural characterization of metabolites. In this study, 30 metabolites were detected and identified in vivo, and demethylation and hydroxylation were confirmed as the primacy metabolic pathway for SL in rat plasma. In conclusion, the presently developed methodology was suitable for biotransformation research of SL and will find wide use in metabolic studies for other herbal medicines. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
1000.
Chen Hui Sharma Sunil K. Sharma Priyanka R. Chi Kai Fung Eric Aubrecht Katherine Keroletswe Ngonye Chigome Samuel Hsiao Benjamin S. 《Cellulose (London, England)》2021,28(13):8611-8628
Cellulose - Mercury contamination in drinking water is a worldwide problem due to its severely harming effects on the human body. A nanostructured natural bioadsorbent, carboxycellulose nanofiber... 相似文献