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991.
Series of dimeric compounds of different skeletal shapes consisting of two triad aromatic ester type mesogenic moieties connected via polymethylene spacers were synthesized and their liquid crystalline properties compared. The two mesogenic units are connected in either Hor T-shape or in linear fashion. In general, it was found that mesophase temperature ranges for the T- and linear-shaped compounds are much wider than for the H-shaped compounds. Moreover, the former are enantiotropic thermotropic materials, whereas the latter tend to be monotropic unless the spacer length is fairly long, i.e. longer than decamethylene. Among the three series, the linearly linked twin compounds had the highest melting and isotropization temperatures. All of the linear and T-shaped dimeric compounds reported in this article form only nematic mesophases. 相似文献
992.
Adsorption and desorption of ions at interface between liquid crystal and alignment layer in liquid crystal displays play a crucial role in residual direct current voltage associated with image sticking. In this article, the dependency of such adsorption and desorption of ions on resistivity of alignment layer and sign of liquid crystal dielectric anisotropy in the fringe-field liquid crystal cell has been investigated. Our studies show that the time constant of ions during adsorption and desorption depends upon resistivity and dielectric constant of liquid crystal and alignment layer, and most strongly influenced by the resistivity of alignment layer such that the one with lower resistivity in two orders shows much faster adsorption and desorption at the interface than that of the one with higher resistivity. 相似文献
993.
Guan Chunfeng Li Xiaozhou Wang Gang Ji Jing Jin Chao Tchouopou Lontchi Josine 《Applied biochemistry and biotechnology》2013,169(2):636-650
Cholera toxin B-subunit (CTB) has been widely used to facilitate antigen delivery by serving as an effective mucosal carrier molecule for the induction of oral tolerance. However, whether CTB can be used as a transmucosal carrier in the delivery of not only vaccines but also therapeutic proteins has not been widely studied. Thus, we investigate here the concept of receptor-mediated oral delivery of lumbrokinase (LK) proteins which is an important fibrinolytic enzyme derived from earthworm. CTB and LK, separated by a furin cleavage site, was expressed via Pichia pastoris. The activity and proper folding of recombinant protein in yeast were confirmed by Western blot analysis, fibrin plate assays, and GM1-ganglioside ELISA. Following oral administration of recombinant protein, the thrombosis model of rats and mice revealed that the oral treatment of rCTB–LK has a more significant anti-thrombotic effect on animals compared with rLK. It is possible to conclude that CTB can successfully enhance its fusion protein LK to be absorbed. The use of CTB as a transmucosal carrier in the delivery of not only vaccines but also therapeutic proteins was supported. 相似文献
994.
Sungchil Kang Alexander Efremov Sun Jin Yun Jinyoung Son Kwang-Ho Kwon 《Plasma Chemistry and Plasma Processing》2013,33(2):527-538
An investigation of etching behaviors for Mo and Al2O3 thin films in O2/Cl2/Ar inductively coupled plasmas at constant gas pressure (6 mTorr), input power (700 W) and bias power (200 W) was carried out. It was found that an increase in Ar mixing ratio for Cl2/Ar plasma results in non-monotonic etching rates with the maximums of 160 nm/min at 60 % Ar for Mo and 27 nm/min at 20 % Ar for Al2O3. The addition of O2 in the Cl2/Ar plasma causes the non-monotonic Mo etching rate (max. 320 nm/min at 40–45 % O2) while the Al2O3 etching rate decreases monotonically. The model-based analysis of etching kinetics allows one to relate the non-monotonic etching rates in Cl2/Ar plasma to the change in the etching regime from the ion-flux-limited mode (at low Ar mixing ratios) to the neutral-flux-limited mode (for high Ar mixing ratios). In the Cl2/O2/Ar plasma, the non-monotonic Mo etching rate is probably due to the change in reaction probability. 相似文献
995.
In this paper, a new water-soluble initiator system, 2-bromopropane/CuSO4/sodium ascorbate, was used as the initiator for emulsion polymerization. Radical emulsion polymerization of styrene was successfully carried out at 80 °C by using sodium dodecylbenzenesulfonate as the emulsifier. The 2-bromopropane/CuSO4/sodium ascorbate-initiated emulsion polymerization shows the controlled free-radical polymerization features with linear growth of molecular weight. Polystyrene with a relatively high molecular weight and a narrow molecular weight distribution can be synthesized by this method. On the other hand, stable polystyrene latex can be obtained, and the size of the polystyrene latex increased with the increase in monomer conversion. 相似文献
996.
Dongxia Nie Ying Liang Tianshu Zhou Qian Sun Litong Jin 《International journal of environmental analytical chemistry》2013,93(7):832-843
FDU-15 is a hexagonal mesoporous material with nanometer-sized, highly ordered arrays and large special surface area. In this work, FDU-15-Pt with 2.0%, 5.0% and 8.0% Pt loading were synthesised and used for electrochemical detection of trace nitroaromatic compounds (NACs). The FDU-15-Pt samples were characterised by CO Chemisorption, transmission electron microscopy (TEM) and X-ray diffraction (XRD). It has been demonstrated that FDU-15-Pt with 2.0% Pt loading has the smallest Pt particle size of 2.9?nm, highest Pt metal dispersion of 37.7% and largest Pt metal surface area of 21.36?m2?g?1. The FDU-15-Pt/PDDA modified electrode were assembled by electrostatic adsorption of Poly (diallyldimethylammonium chloride) (PDDA) and FDU-15-Pt. The 2.0% FDU-15-Pt modified sensor showed higher selectivity for NACs than those of 5.0% and 8.0% FDU-15-Pt, which were verified by electrochemical experiments. A linear response over TNT concentration ranging from 8.8?×?10?9?M to 1.2?×?10?5 M was exhibited with a low detection limit of 2.9?×?10?9?M (S/N?=?3). Moreover, the proposed 2.0% FDU-15-Pt/PDDA modified sensor has been applied to the detection of NACs in spiked environmental water samples and shows promise for fast and accurate determination of trace NACs in real samples. 相似文献
997.
Chuan Jie Cheng Quan Lei Fu Xiong Xiong Bai Shao Jin Liu Liang Shen Wu Qin Fan Hong Xia Li 《Chemical Papers》2013,67(3):336-341
A novel cationic gemini surfactant has been readily synthesised in 70 % total yield. The functional gemini surfactant can act both as an emulsifier and an atom transfer radical polymerisation (ATRP) initiator in mini-emulsion polymerisation of methyl methacrylate (MMA), in which no other emulsifier was required. 1-(Dimethylamino)dodecane (N,N-dimethyldodecylamine, DMDA) was found to be a good ligand in the activator generated by electron transfer (AGET) ATRP reaction. Kinetic studies indicated that the polymerisation featured controlled/living radical polymerisation. 相似文献
998.
Kongkai Zhu Junyan Lu Zhongjie Liang Xiangqian Kong Fei Ye Lu Jin Heji Geng Yong Chen Mingyue Zheng Hualiang Jiang Jun-Qian Li Cheng Luo 《Journal of computer-aided molecular design》2013,27(3):247-256
New Delhi metallo-β-lactamase-1 (NDM-1) has emerged as a major global threat to human health for its rapid rate of dissemination and ability to make pathogenic microbes resistant to almost all known β-lactam antibiotics. In addition, effective NDM-1 inhibitors have not been identified to date. In spite of the plethora of structural and kinetic data available, the accurate molecular characteristics of and details on the enzymatic reaction of NDM-1 hydrolyzing β-lactam antibiotics remain incompletely understood. In this study, a combined computational approach including molecular docking, molecular dynamics simulations and quantum mechanics/molecular mechanics calculations was performed to characterize the catalytic mechanism of meropenem catalyzed by NDM-1. The quantum mechanics/molecular mechanics results indicate that the ionized D124 is beneficial to the cleavage of the C–N bond within the β-lactam ring. Meanwhile, it is energetically favorable to form an intermediate if no water molecule coordinates to Zn2. Moreover, according to the molecular dynamics results, the conserved residue K211 plays a pivotal role in substrate binding and catalysis, which is quite consistent with previous mutagenesis data. Our study provides detailed insights into the catalytic mechanism of NDM-1 hydrolyzing meropenem β-lactam antibiotics and offers clues for the discovery of new antibiotics against NDM-1 positive strains in clinical studies. 相似文献
999.
Qumei Jin Fengyu Qu Jingjie Jiang Yan Dong Wei Guo Huiming Lin 《Journal of Sol-Gel Science and Technology》2013,66(3):466-471
A novel dual-drug delivery system based on mesoporous-macroporous silica/polyelectrolytes-SBA-15 has been synthesized. The structure and composition of these materials were characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and N2 adsorption–desorption measurements. In this system, water-soluble metformin hydrochloride and fat-soluble ibuprofen were used as model drugs to study the controlled release behavior. The pH-controlled release of individual drugs was obtained by the primary release of metformin hydrochloride from polyelectrolytes-SBA-15 in acid condition and the predominant release of ibuprofen from MMC in alkaline environment. The results show that the polyelectrolytes-SBA-15/mesoporous-macroporous silica can be used as dual-drug release system and the individual drug can be controlled release with the change of pH value of the environment. 相似文献
1000.
Junsong Yang Juanjuan Zhao Hailong Wang Shengyi Zhang Jiming Song Changjie Mao Helin Niu Baokang Jin Yupeng Tian 《Journal of Sol-Gel Science and Technology》2013,67(3):660-664
By dipping-lifting in sol–gel solution and reducing process, the TiO2 composite film on the glass plate was first prepared. Then, the PbSe/BaTiO3/TiO2 composite film was fabricated by interface reaction with BaTiO3 and PbSe on the surface of TiO2 composite film. The characterization results show that the uniform porous TiO2 film is made up of the anatase crystal, and the PbSe/BaTiO3/TiO2 composite film is constructed by doping or depositing BaTiO3 and PbSe nanoparticles on the surface of TiO2 film. The photoelectrochemical measurement results indicate that the PbSe/BaTiO3/TiO2 composite film has an interesting photoelectrochemical conversion property. 相似文献