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131.
Ivan T. Devedjiev 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1785-1787
A facile method for the synthesis of acetyl phosphate by a reaction of 2-hydroxypropylphosphate with acetic acid is described. 相似文献
132.
Suyu Shi Yamin Pan Bo Lu Changyu Shen Chuntai Liu 《Journal of Macromolecular Science: Physics》2014,53(8):1431-1441
A bipolar membrane (BPM) of carboxymethyl cellulose (CMC) and chitosan (CS) with superior performance was prepared based on the macromolecules containing metal elements. A carboxymethyl cellulose cation layer was modified by copper phthalocyanine 16-carboxylic acid (CuPc(COOH)16) to improve its ion exchange capacity as well as cation transfer rate and promote water splitting at the intermediate layer. Chitosan was crosslinked with acetyl ferrocene to prepare the anion layer. A casting method was used to prepare the BPM which showed excellent physical and chemical properties after modification. To improve the compatibility of the anion-exchange layer and cation-exchange layer, polyethylene glycol (PEG) was blended with both the CMC and CS. Scanning electron microscopy (SEM) images illustrated a structure that consisted of an anion layer and a cation layer that were closely combined with each other. The swelling results implied a proper hydrophilic performance and good shape stability in an alkali solution ([OH?]≤10 mol·L?1) of the BPM. After modification, the BPM with the metal elements exhibited good thermal stability, as shown by the thermogravimetry (TG) results. Compared with the BPM that was unmodified, both the AC impedance and the working voltage were decreased sharply. Furthermore, the modified BPM exhibited higher ion penetrability which is beneficial for its wide application. 相似文献
133.
Glycosylation of 2-O-acyl fructopyranosides was investigated, which were shown to be effective glycosyl donors for d-fructopyranoside synthesis with good β-selectivity and yields. For bulky acceptor 4e, α-anomer 5e was obtained with α/β = 65:23. Unexpected ring-opening was observed during acetylation of 9, indicating the sensitivity of the fructopyranosyl ring. 相似文献
134.
Naglaa Salem El-Sayed Amir Nasrolahi Shirazi Magda Goda El-Meligy Ahmed Kamel El-Ziaty David Rowley Jiadong Sun Zenat Adeeb Nagib Keykavous Parang 《Tetrahedron letters》2014
A novel class of 6-indolypyridine-3-carbonitrile derivatives were synthesized and evaluated for antiproliferative activities to establish structure–activity relationship. The synthesis was carried out through one-pot multicomponent reaction of 3-acetylindole, aromatic aldehydes, ethyl cyanoacetate, and ammonium acetate in the presence of piperidine as a catalyst, using a microwave irradiation method or a traditional thermal method. This was followed by chlorination for compounds 13a–e and subsequent nucleophilic substitution of the chlorine group by ethylenediamine at C2 position of the pyridine ring. The antiproliferative activity of these new nicotinonitriles was evaluated against human ovarian adenocarcinoma (SK-OV-3), breast adenocarcinoma (MCF-7), and cervix adenocarcinoma (HeLa) cells. Among all compounds, 2-((2-aminoethyl)amino)-4-aryl-6-indolylnicotinonitriles series (15a, 15b, 15d, and 15e) exhibited higher antiproliferative activity on the three cancer cell lines with IC50 values of 4.1–13.4 μM. 相似文献
135.
A capillary electrophoresis method and a durable choline biosensor were developed for measuring serum cholinesterase (EC 3.1.1.8) activity, a useful clinical index for liver function. The former is based on separation of benzoate and benzoylcholine (the artificial substrate of cholinesterase) in an uncoated fused-silica capillary. The migration time of benzoylcholine and benzoate was 1.3 min and 5.5 min, respectively. By the peak areas of A233 signals, the linear dynamic ranges for both analytes were 0.01–50.0 mM, and the relative standard deviations of 1.0 mM benzoylcholine and benzoate were less than 4% and 6%, respectively.The FIA-choline sensor was constructed with the working electrode of the flow cell covered with a natural chitinous membrane purified from Taiwanese soldier crab, Mictyris brevidactylus. The biomembrane served as the supporting material for enzyme immobilization (choline oxidase, EC 1.1.3.17), and also prevented protein adsorption on the electrode surface. The calibration curve was linear between 0.05 and 5.0 mM (r = 0.999). The relative standard deviations for 1.0 mM choline (n = 7) were less than 3%, and the activity of the bioactive membrane lasted for about 2 months. The analytical results of both methods correlated well (r = 0.940). 相似文献
136.
Song Z Ge D Ishii K Yamada H Toriumi K Watanabe H Nabeshima T Fukushima T 《Biomedical chromatography : BMC》2012,26(2):147-151
The concentration of brain N-acetylaspartic acid (NAA) in mice was determined by high-performance liquid chromatography (HPLC) using fluorescence detection after pre-column derivatization with 4-N,N-dimethylaminosulfonyl-7-N-(2-aminoethyl)amino-2,1,3-benzoxadiazole (DBD-ED). Six different brain parts, namely, the prefrontal cortex, olfactory bulb, nucleus accumbens, striatum, cerebellum and hippocampus, of male C57BL6/J mice, were investigated. The NAA concentration (nmol/mg protein) was highest in the olfactory bulb (58.2 ± 4.0, n = 8) and lowest in the hippocampus (42.8 ± 1.6, n = 8). The proposed HPLC method with fluorescence detection was successfully used to determine the NAA concentration in each investigated brain area. 相似文献
137.
138.
《Analytical letters》2012,45(5):1159-1169
Abstract A thick-film metallized platinum electrode operated in the voltammetric mode is used to determine the cholinesterase activity in human serum and erythocytes. Inhibitors of the enzyme can also be quanitified by the electrode with cholinesterase either immobilized directly on the electrode surface or dissolved in the test medium. 相似文献
139.
Michael J. Selig William S. Adney Michael E. Himmel Stephen R. Decker 《Cellulose (London, England)》2009,16(4):711-722
Analysis of variously pretreated corn stover samples showed neutral to mildly acidic pretreatments were more effective at
removing xylan from corn stover and more likely to maintain the acetyl to xylopyranosyl ratios present in untreated material
than were alkaline treatments. Retention of acetyl groups in the residual solids resulted in greater resistance to hydrolysis
by endoxylanase alone, although the synergistic combination of endoxylanase and acetyl xylan esterase enzymes permitted higher
xylan conversions to be observed. Acetyl xylan esterase alone did little to improve hydrolysis by cellulolytic enzymes, although
a direct relationship was observed between the enzymatic removal of acetyl groups and improvements in the enzymatic conversion
of xylan present in substrates. In all cases, effective xylan conversions were found to significantly improve glucan conversions
achievable by cellulolytic enzymes. Additionally, acetyl and xylan removal not only enhanced the respective initial rates
of xylan and glucan conversion, but also the overall extents of conversion. This work emphasizes the necessity for xylanolytic
enzymes during saccharification processes and specifically for the optimization of acetyl esterase and xylanase synergies
when biomass processes include milder pretreatments, such as hot water or sulfite steam explosion. 相似文献
140.
Title compounds 2′,2′-dimethylcholesta-2,4-dien[3,2-b]-pyran-4′-one(3),2′,2′-dimethyl-3β-substituted cholesta-4,6-dien[7,6- b]-pyran-4′-one(6a,b)and(6c)were prepared by the cyclization of 2-acetylcholesta-2,4-dien-3-ol(2),6-acetyl-3β-substituted- cholesta-4,6-dien-7-ol(5a,b)and(5c)respectively,with pyrrolidine,dry benzene and dry acetone using Dean Stark separator through conventional heating.Furthermore,compounds were also found to be active against Mycobacterium tuberculosis. 相似文献