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1.
Hongyan Zhang Liuqing Xie Pengjun Xu 《International journal of environmental analytical chemistry》2013,93(8):561-569
A rapid and simple method for determining the plant growth regulator hexanoic acid 2-(diethylamino) ethyl ester (DA-6) in pakchoi and soil using gas chromatography-mass spectrometry (GC-MS) has been developed. For this purpose, a single step was used to extract DA-6 with dichloromethane from aqueous-acetone extracts of vegetables and soil. Average recoveries of DA-6 in pakchoi and soil were between 85% and 104% at both spiking levels 0.01 and 0.1 mg kg?1. Relative standard deviations (RSD) were less than 11% for all of the recovery tests. The degradation of DA-6 in pakchoi and soil was studied. The results showed that DA-6 degradation in pakchoi and soil coincided with C = 3.9903 e?0.0516 t , C = 0.3476 e?0.0224 t , respectively; the half-lives were 13.43 h and 30.94 h in pakchoi and soil in Beijing, respectively. 相似文献
2.
Nickel-cobalt layered double hydroxides (NiCo-LDH) were successfully deposited on nickel foam by a facile hydrothermal method using polyvinyl pyrrolidone (PVP) as the structure-directing reagent. The effect of PVP on the morphology and electrochemical performance of binder-free NiCo-LDH electrode for supercapacitor were investigated in detail. The prepared NiCo-LDH presented good dispersivity and appeared different flower-like structure via the addition of PVP. Specially, the NiCo-LDH electrode using 1 g of PVP exhibited a superior performance with a high-specific capacity of 724.9 C g?1 at a current density of 1 A g?1 and 577.1 C g?1 at 10 A g?1. In addition, a hybrid supercapacitor (HSC) based on the optimized NiCo-LDH as positive electrode and activated carbon as negative electrode was assembled with 6 M KOH as the electrolyte. The HSC device can deliver an energy density of 32.3 Wh kg?1 at the power density of 387.1 W kg?1. Moreover, the HSC device exhibited a good cycling stability with a retention rate of 94.0% after 2000-cycle charge-discharge test at 3 A g?1. 相似文献
3.
Huimin Wang Rui Ma Pengjun Shi Xianli Xue Huiying Luo Huoqing Huang Yingguo Bai Peilong Yang Bin Yao 《Applied biochemistry and biotechnology》2014,174(1):328-338
An α-galactosidase gene (gal36A4) of glycosyl hydrolase family 36 was identified in the genome of Alicyclobacillus sp. A4. It contains an ORF of 2,187 bp and encodes a polypeptide of 728 amino acids with a calculated molecular mass of 82.6 kDa. Deduced Gal36A4 shows the typical GH36 organization of three domains—the N-terminal β-sheets, the catalytic (β/α)8-barrels, and the C-terminal antiparallel β-sheet. The gene product was produced in Escherichia coli and showed both hydrolysis and transglycosylation activities. The optimal pH for hydrolysis activity was 6.0, and a stable pH range of 5.0–11.0 was found. The enzyme had a temperature optimum of 60 °C. It is specific for α-1,6-glycosidic linkages and had a K m value of 1.45 mM toward pNPGal. When using melibiose as both donor and acceptor of galactose, Gal36A4 showed the transfer ratio of 23.25 % at 96 h. With respect to acceptor specificity, all tested monosaccharides, disaccharides, and oligosaccharides except for D-xylose and L-arabinose were good acceptors for transglycosylation. Thus, Gal36A4 may find diverse applications in industrial fields, especially in the food industry. 相似文献
4.
Pengjun Shi Ning Li Peilong Yang Yaru Wang Huiying Luo Yingguo Bai Bin Yao 《Applied biochemistry and biotechnology》2010,162(3):707-718
An α-l-arabinofuranosidase gene, abf51S9, was cloned from Streptomyces sp. S9 and successfully expressed in Escherichia coli BL21 (DE3). The full-length gene consisted of 1,506 bp and encoded 501 amino acids with a calculated mass of 55.2 kDa. The
deduced amino acid sequence was highly homologous with the α-l-arabinofuranosidases belonging to family 51 of the glycoside hydrolases. The recombinant protein was purified to electrophoretic
homogeneity by Ni-NTA affinity chromatography and subsequently characterized. The optimal pH and temperature for the recombinant
enzyme were 6.0 and 60∼65 °C, respectively. The enzyme showed a broad pH range of stability, retaining over 75% of the maximum
activity at pH 5.0 to 11.0. The specific activity, K
m, and V
max with p-nitrophenyl-α-l-arabinofuranoside as substrate were 60.0 U mg−1, 1.45 mM, and 221 μmol min−1 mg−1, respectively. Abf51S9 showed a mild but significant synergistic effect in combination with xylanase on the degradation of
oat-spelt xylan and soluble wheat arabinoxylan substrates with a 1.19- and 1.21-fold increase in the amount of reducing sugar
released, respectively. These favorable properties make Abf51S9 a good candidate in various industrial applications. 相似文献
5.
Yanmin Tian Rutao Liu Wansong Zong Feng Sun Meijie Wang Pengjun Zhang 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(2):908-911
Hydroxyl radicals generated from Fenton reaction were used to damage the angiotensin. The oxidative damage degree and sites of peptides were measured by HPLC–MS and MS/MS. Experimental results proved that the oxidative damage degree increased with longer reaction time. The results also showed that the side chains of phenylalanine and tyrosine in angiotension can be attacked by hydroxyl radicals to form the oxidative products. A new strategy was established to monitor the oxidative degree and sites of peptides and laid the foundation for protein oxidation. This method can be used to investigate the mechanism of protein oxidative damage caused by oxidative stress which is induced by environmental pollutants and physiological activities. There will also be a wide application in the research of pathogenesis of some disease related to oxidative stress. 相似文献
6.
We demonstrate collective atomic recoil motion with a dilute, ultracold, degenerate fermion gas in a single spin state. By utilizing an adiabatically decompressed magnetic trap with an aspect ratio different from that of the initial trap, a momentum-squeezed fermion cloud is achieved. With a single pump pulse of the proper polarization, we observe, for the first time, multiple wave-mixing processes that result in distinct collective atomic recoil motion modes in a degenerate fermion cloud. Contrary to the case with Bose condensates, no pump-laser detuning asymmetry is present. 相似文献
7.
8.
合理的巡游出租车运价体系是缓解行业矛盾和促进行业良性发展的重要保障.为了充分体现运价在供需调节中的杠杆作用,运用系统动力学构建了巡游出租车运价动态调整模型.以宁波市巡游车和网约车运营数据对模型参数进行标定,验证了模型的有效性;以市场供需平衡为目标,分别模拟了高峰、低峰不同需求水平下动态加价、减价对市场供需平衡状态的影响分析以及不同网约车吸引度水平下巡游出租车运价动态调整策略.模型结果表明:(1)当运价增加0.6元km~(-1)时,可使高峰时段供需接近平衡状态,有效地抑制了高峰需求水平,且保证了巡游车运营总体收益增加;(2)当巡游车和网约车市场业务量之比约为10:4.5和10:8时,巡游车加价分别为0.6和-0.4元km~(-1),当巡游车处于竞争优势时,适度加价可期获得更大收益;处于劣势时,适度降价以提高自身竞争能力. 相似文献
9.
通过对包含无关项布尔逻辑函数SOP(Sum—of-Products)展开式和MPRM(MixedPolarityReed—Muller)展开式的研究,结合基于系数矩阵的FPRM(FixedPolarityReed—Muller)展开式极性转换算法,提出了一种包含无关项逻辑函数MPRM展开式最小化算法.首先将包含无关项逻辑函数SOP展开式转换为MPRM展开式,并用系数矩阵的形式表示;然后删除函数中的冗余变量,归纳出一种包含无关项MPRM展开式最小化算法,得到与项数较少的MPRM展开式;最后随机选取15个MCNC基准电路进行测试,结果表明该算法能有效地优化电路面积. 相似文献
10.
Qiong Liu Peilong Yang Huiying Luo Pengjun Shi Huoqing Huang Kun Meng Bin Yao 《Applied biochemistry and biotechnology》2012,166(6):1442-1453
An endo-β-1,4-mannanase encoding gene, man5, was cloned from Bispora antennata CBS 126.38, which was isolated from a beech stump. The cDNA of man5 consists of 1,299 base pairs and encodes a 432-amino-acid protein with a theoretical molecular mass of 46.6 kDa. Deduced
MAN5 exhibited the highest amino acid sequence identity of 58% to a β-mannanase of glycoside hydrolase family 5 from Aspergillus aculeatus. Recombinant MAN5 was expressed in Pichia pastoris and purified to electrophoretic homogeneity. The specific activity of the final preparation towards locust bean gum was 289
U mg−1. MAN5 showed optimal activity at pH 6.0 and 70 °C and had good adaptation and stability over a broad range of pH values.
The enzyme showed more than 60% of peak activity at pH 3.0–8.0 and retained more than 80% of activity after incubation at
37 °C for 1 h in both acid and alkaline conditions (pH 4.0–11.0). The K
m and V
max values were 1.33 mg ml−1 and 444 μmol min−1 mg−1 and 1.17 mg ml−1 and 196 μmol min−1 mg−1 for locust bean gum and konjac flour, respectively. Of all tested metal ions and chemical reagents, Co2+, Ni2+, and β-mercaptoethanol enhanced the enzyme activity at 1 mM, whereas other chemicals had no effect on or partially inhibited
the enzyme activity. MAN5 was highly resistant to acidic and neutral proteases (trypsin, α-chymotrypsin, collagenase, subtilisin
A, and proteinase K). By virtue of the favorable properties of MAN5, it is possible to apply this enzyme in the paper and
food industries. 相似文献