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141.
Song Yun Weizhong Qian Chaojie Cui Yuntao Yu Chao Zheng Yi Liu Qiang Zhang Fei Wei 《Journal of Energy Chemistry》2013,22(4):567-572
For the synthesis of single-walled carbon nanotubes (SWCNTs) from CH4 over a Fe/MgO catalyst, we proposed a coupled Downer-turbulent fluidized-bed (TFB) reactor to enhance the selectivity and yield (or production rate) of SWCNTs. By controlling a very short catalyst residence time (1–3 s) in the Downer, only part of Fe oxides can be reduced to form Fe nano particles (NPs) available for the growth of SWCNTs. The percentage of unreduced Fe oxides increased and the yield of SWCNTs decreased accordingly with the increase of catalyst feeding rate in Downer. SWCNTs were preferentially grown on the catalyst surface and inhibited the sintering of the Fe crystallites which would be formed thereafter in the downstream TFB, evidenced by TEM, Raman and TGA. The coupled Downer-turbulent fluidized-bed reactor technology allowed higher selectivity and higher production rate of SWCNTs as compared to TFB alone. 相似文献
142.
The preparation of biodegradable and thermoresponsive enzyme–polymer bioconjugates with controllable enzymatic activity via reversible addition−fragmentation chain transfer (RAFT) polymerization and amidation conjugation reaction is presented. A new 2-mercaptothiazoline ester functionalized RAFT agent with intra-disulfide linkage was synthesized and used as chain transfer agent (CTA) to generate a biocompatible homopolymer, poly(ethyleneglycol) acrylate (polyPEG-A) and a thermoresponsive copolymer of poly(ethyleneglycol) acrylate with di(ethyleneglycol)ethyl ether acrylate [poly(PEG-A-co-DEG-A)]. These biodegradable and thermoresponsive polymers were then conjugated to the surface of glucose oxidase (GOx) under mild condition to afford the biodegradable and thermoresponsive enzyme–polymer conjugates. Cleavage of the polymer chains from the GOx surface obviously recovered the enzymatic activity. The thermoresponsive test of GOx-poly(PEG-A-co-DEG-A) revealed that the bioconjugate exhibited regular enzymatic activity fluctuation upon the temperature change below or above the lower critical solution temperature (LCST). The as-prepared enzyme–polymer conjugates were also characterized using 1H NMR, UV–vis spectroscopy, polyacrylamide gel electrophoresis (PAGE) and biocatalytic activity tests. These smart enzyme–polymer conjugates would envision promising applications in biotechnology and biomedicine. 相似文献
143.
Two novel tricoordinate phosphorous saccharides, methyl 4,6-O-benzylidene- α -D-glucopyranoside 2,3-cyclic phosphite ethyl ester 3 and its mannoside analogue 5 were synthesized by the reaction of protected pyrannosides (1 and 4) with ethyl dichlorophosphite 2. Addition of 2,3-butanedione to 3 resulted in the formation of pentacoordinate phosphorous compound 6. 相似文献
144.
The applications of a new supported tribromide reagent based on poly(vinylbenzyltrimethylammonium hydroxide) resin (Amberlite 717) were reported. This supported tribromide resin was used directly in α-bromination and α-bromoacetalization of acetophenones without any other catalyst under mild conditions. The effects of solvents and the amount of the supported tribromide resin on the reactions were investigated. Under the optimal conditions, most of α-bromo and α-bromoacetal of acetophenones were selectively obtained in excellent yields. 相似文献
145.
Phase equilibria of the quaternary NaCl–NaBr–Na2SO4–H2O system at 323 K were studied by the isothermal dissolution equilibrium method. The solubilities of salts and densities of saturated solutions were determined. Solid solutions [Na(Cl, Br)] were found in the experiments. The phase diagram of the quaternary system has no invariant point, but has one univariant curve at the boundary of Na(Cl, Br) and Na2SO4 crystallization fields. The experimental results show that an increase of the NaBr concentration is accompanied by an obvious increase of the solution density and the decrease of the solubilities of NaCl and Na2SO4. 相似文献
146.
Jian-Zhong Jiang Li-Ting Lu Zheng-Yong Liang Zheng-Gang Cui 《Journal of Dispersion Science and Technology》2013,34(1):125-127
Highly regiospecific mononitration of phenols and substituted phenols was carried out in TX100-based microemulsion. The use of inexpensive and relatively nontoxic acidic reagent is an advantage of this method. The effect of various parameters such as concentration of NaNO3, temperature, and agitation speed on reaction system have been investigated. Exclusive ortho-selectivity was observed for all the phenols subjected to this protocol. 相似文献
147.
Yucai Lü Ning Li Xufeng Yuan Binbin Hua Jungang Wang Masaharu Ishii Yasuo Igarashi Zongjun Cui 《Applied biochemistry and biotechnology》2013,171(7):1578-1588
The effect of a non-cellulolytic bacterium W2-10 (Geobacillus sp.) on the cellulose-degrading activity of a cellulolytic bacterium CTL-6 (Clostridium thermocellum) was determined using cellulose materials (paper and straw) in peptone cellulose solution (PCS) medium under aerobic conditions. The results indicated that in the co-culture, addition of W2-10 resulted in a balanced medium pH, and may provide the required anaerobic environment for CTL-6. Overall, addition of W2-10 was beneficial to CTL-6 growth in the adverse environment of the PCS medium. In co-culture with W2-10, the CTL-6 cellulose degradation efficiency of filter paper and alkaline-treated wheat straw significantly increased up to 72.45 and 37.79 %, respectively. The CMCase activity and biomass of CTL-6 also increased from 0.23 U ml?1 and 45.1 μg ml?1 (DNA content) up to 0.47 U ml?1 and 112.2 μg ml?1, respectively. In addition, co-culture resulted in accumulation of acetate and propionate up to 4.26 and 2.76 mg ml?1. This was a respective increase of 2.58 and 4.45 times, in comparison to the monoculture with CTL-6. 相似文献
148.
Yuan Cui Yanhui Li Qian Duan Toyoji Kakuchi 《Applied biochemistry and biotechnology》2013,169(1):239-249
Hyaluronic acid is a naturally ionic polysaccharide with cancer cell selectivity. It is an ideal candidate material for delivery of anticancer agents. In this study, hyaluronic acid (HA) micro-hydrogel loaded with anticancer drugs was prepared by the biotin–avidin system approach. Firstly, carboxyl groups on HA were changed into amino groups with adipic acid dihydrazide (ADH) to graft with biotin by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride named as HA–biotin. When HA–biotin solution mixed with doxorubicin hydrochloride (DOX·HCl) was blended with neutravidin, the micro-hydrogels would be formed with DOX loading. If excess biotin was added into the microgel, it would be disjointed, and DOX will be released quickly. The results of the synthesis procedure were characterized by 1H-NMR and FTIR; ADH and biotin have been demonstrated to graft on the HA molecule. A field emission scanning electron microscope was used to observe morphologies of HA micro-hydrogels. Furthermore, the in vitro DOX release results revealed that the release behaviors can be adjusted by adding biotin. Therefore, the HA micro-hydrogel can deliver anticancer drugs efficiently, and the rate of release can be controlled by biotin-specific bonding with the neutravidin. Consequently, the micro-hydrogel will perform the promising property of switching in the specific site in cancer therapy. 相似文献
149.
Hongtao Cui Minmin Wang Wanzhong Ren Yan Liu Yunan Zhao 《Journal of Sol-Gel Science and Technology》2013,66(3):512-517
Silica monoliths embedded with high concentration of γ-Fe2O3 or TiO2 nanoparticles were prepared by a sol–gel procedure designed according to the inherent properties of oxide colloids. In the first step, highly dispersible oxide nanoparticles were produced using an in situ modification sol–gel strategy. Then, these particles were re-dispersed in silicon alkoxide-containing solution to form a stable colloidal solution. The hydrolysis and condensation reactions of alkoxide were catalyzed by an organic base (morpholine). Due to the large molecule size of morpholine, the electric double layer on the surface of colloidal particles was not compressed by the ionized morpholine molecules. The colloidal solution thus remained stable during the gelation process. Through this procedure, oxide nanoparticles could be immobilized homogeneously in the pores of a silica matrix, forming highly transparent and crack-free monoliths. 相似文献
150.
Ying‐Lu Cui Ji‐Long Zhang Prof. Qing‐Chuan Zheng Rui‐Juan Niu Yu Xu Prof. Hong‐Xing Zhang Chia‐Chung Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):549-557
Cytochrome P450 (CYP) 7B1 is a steroid cytochrome P450 7α‐hydroxylase that has been linked directly with bile salt synthesis and hereditary spastic paraplegia type 5 (SPG5). The enzyme provides the primary metabolic route for neurosteroids dehydroepiandrosterone (DHEA), cholesterol derivatives 25‐hydroxycholesterol (25‐HOChol), and other steroids such as 5α‐androstane‐3β,17β‐diol (anediol), and 5α‐androstene‐3β,17β‐diol (enediol). A series of investigations including homology modeling, molecular dynamics (MD), and automatic docking, combined with the results of previous experimental site‐directed mutagenesis studies and access channels analysis, have identified the structural features relevant to the substrate selectivity of CYP7B1. The results clearly identify the dominant access channels and critical residues responsible for ligand binding. Both binding free energy analysis and total interaction energy analysis are consistent with the experimental conclusion that 25‐HOChol is the best substrate. According to 20 ns MD simulations, the Phe cluster residues that lie above the active site, particularly Phe489, are proposed to merge the active site with the adjacent channel to the surface and accommodate substrate binding in a reasonable orientation. The investigation of CYP7B1–substrate binding modes provides detailed insights into the poorly understood structural features of human CYP7B1 at the atomic level, and will be valuable information for drug development and protein engineering. 相似文献