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131.
<正>PTPMEG1 is an intracellular protein tyrosine phosphatase(PTP),which contains FERM and PDZ domains. This study focuses our attention on the expression,purification and characterization of catalytic domain of PTPMEG1(△MEG1) and preparation of its polyclonal antibody.A cDNA fragment encoding△MEG1 protein(amino acid residues 643—926) was amplified by PCR and then cloned into the pT7-7 vector.Both soluble and insoluble recombinant△MEG1 proteins were observed after induction by IPTG.Soluble△MEG1 was purified via two chromatographic steps,and the purified enzyme was characterized.With para-nitrophenylphosphate(pNPP) as a substrate,△MEG1 exhibited typical enzymatic characteristics of classic PTPs and classical Michaelis-Menten kinetics.Insoluble△MEG1,which was mainly distributed in the inclusion body of E.coli cells extracts,was purified by preparative electrophoresis gel for the preparation of the polyclonal antibody.A rabbit was immunized with△MEG1 purified by preparative electrophoresis to generate anti-△MEG1 antibody.Anti-serum was collected on 28th day after initial injection and purified via affinity chromatography.The purified polyconal antibody displayed a satisfactory titer and sensitivity. 相似文献
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By using the pulse propagation equation in the nonlinear dispersive medium, the effects of second- and third-order group-velocity dispersion on pulse evolution in the stretching, amplification and compressing are studied when chirped pulse am-plification is applied to the pulses of a width <30fs, and the optimum dispersion-compensated conditions among the stretcher, amplifier and compressor are deter-mined. From the standpoint of dispersion compensation and control and the com-pressor adjustment, it is proposed that low-groove-density gratings (≤800 line/mm) are the better choices for stretching and compressing the pulses of a width <30fs in chirped-pulse amplification. It is also shown that, with a proper adjustment of the compressor incident angle and grating separation, an exact null in both second- and third-order dispersions can be achieved without any additional dispersion- compensated elements. 相似文献
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Electronic properties of both Pb and S vacancy defects in PbS(1^-00) have been studied using the first-principles density functional theory (DFT) calculations with the plane-wave pseudopotentials. It is found that the density of states (DOS) near the top of the valence band and the bottom of the conduction band is significantly modified by these defects. Our calculation indicates that in the case of S vacancy defects the Fermi energy shifts to the conduction band making it as an n-type PbS (donor). However, in the case of Pb vacancy, because of the appreciable change of the DOS, the system acts as a p-type PbS (accepter). In addition, the structural relaxation shows that the defect leads to outward relaxation of the nearest-neighbouring atoms and inward relaxation of the next-nearest neighbouring atoms. 相似文献
138.
Growth of Semi-Insulating GaN Using N2 as Nucleation Layer Carrier Gas Combining with an Optimized Annealing Time
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Semi-insulating (SI) GaN is grown using N2 as the nucleation layer (NL) carrier gas combined with an optimized annealing time by metalorganic chemical vapour deposition. Influence of using 1-12 and N2 as the NL carrier gas is investigated in our experiment. It is found that the sheet resistance of unintentionally doped GaN can be increased from 10^4 Ω/sq to 10^10 Ω/sq by changing the NL carrier gas from 1-12 to N2 while keeping the other growth parameters to be constant, however crystal quality and roughness of the tilm are degraded unambiguously. This situation can be improved by optimizing the NL annealing time. The high resistance of GaN grown on NL using N2 as the carrier gas is due to higher density of threading dislocations caused by the higher density of nucleation islands and small statistic diameter grain compared to the one using 1-12 as carrier gas. Annealing the NL for an optimized annealing time can decrease the density of threading dislocation and improve the tilm roughness and interface of AlGaN/GaN without degrading the sheet resistance of as-grown GaN signiticantly. High-quality SI GaN is grown after optimizing the annealing time, and AlGaN/GaN high electron mobility transistors are also prepared. 相似文献
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应用 δ2 —加速技巧 ,对 Broyden的计算格式作了修正 .提出了一种新的修正的计算格式 ,给出了计算的步骤及数值例子 . 相似文献