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61.
The oxidation and nitrosation of β-alkanolamines to the corresponding β-ketonitrosamines is reported. The oxidation is carried out with potassium permanganate in acidic medium, followed by nitrosation of the protonated aminoketone, with sodium nitrite, to the corresponding β-ketonitrosamine. 相似文献
62.
Yun Khoon Liew Vasanthakumari Neela Rukman Awang Hamat Syafinaz Amin Nordin Pei Pei Chong 《Electrophoresis》2013,34(3):397-400
The typical concentration of protein loaded varies from 0.13 to 1.40 μg/μL for a classical silver staining method in 2DE gel. Here, we present a simple modified classical silver staining method by modifying the silver impregnation and development reaction steps. This modified method detects the protein spots at extremely low loaded concentrations, ranging from 0.0048 to 0.0480 μg/μL. We recommend this modified silver staining as an excellent method for the limited biological samples used for silver‐stained 2DE analysis. Altogether, the protocol takes close to two days from first dimension separation to second dimension separation, followed by silver staining, scanning, and analysis. 相似文献
63.
Yongbing Pei Yuling Jiang Hong Huang Huanqin Chen 《Journal of Dispersion Science and Technology》2013,34(9):1279-1284
The acrylate redispersible polymer powder (RPP) was produced from acrylate latex via spray drying, which was synthesized by latex polymerization with the configuration of soft core and hard shell. The powder's redispersibility and stability of its reconstituted latex were achieved through incorporating monomer methacrylic acid (MAA), which has functional carboxyl group and can provide an ionization effect in alkaline range. The influence of pH value and MAA amount on the redispersibility and stability were studied. The stabilization mechanism for reconstituted latex was also investigated. The acrylate RPP has good redispersibility at MAA of 4–5% and pH values between 9.0 and 10.0. The reconstituted latex is stable at these conditions due to high zeta potential and strong electrostatic repulsion force. 相似文献
64.
J. J. Ge G. C. Zhang P. Jiang L. Wang H. H. Pei X. L. Liu 《Journal of Dispersion Science and Technology》2013,34(2):278-286
Alkali and alkali/surfactant displacing agents are designed for two kinds of heavy oil. Results of emulsifying capacity, dynamic interfacial tension (IFT) and water-wet core flooding tests show that, although alkaline/surfactant systems exhibit better capacity in emulsification and IFT reduction, oil recovery values of alkaline/surfactant flooding are lower than those of alkaline flooding. Glass-etched micromodel tests further demonstrate that, when alkaline solution penetrates into the oil phase, water streams break into ganglia coating oil film. Water ganglia may be entrapped by narrow throats, consequently presenting a water-oil alternating slug flow. Similar water ganglia also appears in alkaline/surfactant flooding, however, water channeling along the pore surface occurs subsequently, resulting in its relatively lower oil recovery. 相似文献
65.
Junnan Lv Yiqun Chen Honglei Pei Wenhan Yang Zhimin Li Bing Dong Yunhe Cao 《Applied biochemistry and biotechnology》2013,169(8):2326-2340
The β-mannanase gene (1,029 nucleotide) from Bacillus subtilis MAFIC-S11, encoding a polypeptide of 342 amino acids, was cloned and expressed in Pichia pastoris. To increase its expression, the β-mannanase gene was optimized for codon usage (mannS) and fused downstream to a sequence-encoding modified α-factor signal peptide. The expression level was improved by 2-fold. This recombinant enzyme (mannS) showed its highest activity of 24,600 U/mL after 144-h fermentation. The optimal temperature and pH of mannS were 50 °C and 6.0, respectively, and its specific activity was 3,706 U/mg. The kinetic parameters V max and K m were determined as 20,000 U/mg and 8 mg/mL, respectively, representing the highest ever expression level of β-mannanase reported in P. pastoris. In addition, the enzyme exhibited much higher binding activity to chitin, chitosan, Avicel, and mannan. The superior catalytic properties of mannS suggested great potential as an effective additive in animal feed industry. 相似文献
66.
67.
Feng Huang Ying‐Ying Pei Hui‐Hui Zuo Jia‐Liang Chen Yin Yang Prof. Xun‐Cheng Su 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(50):17141-17149
Site‐specific labeling of proteins with lanthanide ions offers great opportunities for investigating the structure, function, and dynamics of proteins by virtue of the unique properties of lanthanides. Lanthanide‐tagged proteins can be studied by NMR, X‐ray, fluorescence, and EPR spectroscopy. However, the rigidity of a lanthanide tag in labeling of proteins plays a key role in the determination of protein structures and interactions. Pseudocontact shift (PCS) and paramagnetic relaxation enhancement (PRE) are valuable long‐range structure restraints in structural‐biology NMR spectroscopy. Generation of these paramagnetic restraints generally relies on site‐specific tagging of the target proteins with paramagnetic species. To avoid nonspecific interaction between the target protein and paramagnetic tag and achieve reliable paramagnetic effects, the rigidity, stability, and size of lanthanide tag is highly important in paramagnetic labeling of proteins. Here 4′‐mercapto‐2,2′: 6′,2′′‐terpyridine‐6,6′′‐dicarboxylic acid (4MTDA) is introduced as a a rigid paramagnetic and fluorescent tag which can be site‐specifically attached to a protein by formation of a disulfide bond. 4MTDA can be readily immobilized by coordination of the protein side chain to the lanthanide ion. Large PCSs and RDCs were observed for 4MTDA‐tagged proteins in complexes with paramagnetic lanthanide ions. At an excitation wavelength of 340 nm, the complex formed by protein–4MTDA and Tb3+ produces high fluorescence with the main emission at 545 nm. These interesting features of 4MTDA make it a very promising tag that can be exploited in NMR, fluorescence, and EPR spectroscopic studies on protein structure, interaction, and dynamics. 相似文献
68.
Approximation properties for solutions to non‐Lipschitz stochastic differential equations with Lévy noise 下载免费PDF全文
In this paper, we consider the non‐Lipschitz stochastic differential equations and stochastic functional differential equations with delays driven by Lévy noise, and the approximation theorems for the solutions to these two kinds of equations will be proposed respectively. Non‐Lipschitz condition is much weaker condition than the Lipschitz one. The simplified equations will be defined to make its solutions converge to that of the corresponding original equations both in the sense of mean square and probability, which constitute the approximation theorems. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
69.
Pei Dang 《Mathematical Methods in the Applied Sciences》2015,38(2):365-379
In this study, we propose some new uncertainty principles for periodic signals with sharper lower bounds than those in the existing ones. The improved lower bounds, in particular, are related to the frequency of the signal. Three examples are employed to demonstrate sharpness of the new uncertainty principles. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
70.
Chao Wang Changpeng Chen Jingyu Zhang Jian Han Qian Wang Kun Guo Pei Liu Mingyu Guan Yingming Yao Yingsheng Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(37):10042-10046
An easily synthesized and accessible N,O‐bidentate auxiliary has been developed for selective C H activation under palladium catalysis. The novel auxiliary showed its first powerful application in C H functionalization of remote positions. Both C(sp2) H and C(sp3) H bonds at δ‐ and ε‐positions were effectively activated, thus giving tetrahydroquinolines, benzomorpholines, pyrrolidines, and indolines in moderate to excellent yields by palladium‐catalyzed intramolecular C H amination. 相似文献