Time-resolved ESI-MS Investigation on Reduction and Alkylation in Unfolding Process of Lysozyme

The kinetic procedure of the unfolding of lysozyme induced by the reduction of disulfide was monitored by the time-resolved ESI-MS with a sheath liquid assistant electrospray interface. It was found that the reduction process for the eight disulfides had a less difference in the reaction time after denatured treatment. In addition, the alkylation of the reduced free thiols was much slower than the reduction procedure. An artifact peak produced by the CID fragmentation in the mass spectra was identified and the possible mechanism of the Hofmann elimination reaction was proposed.     

New Soluble Fluorinated Polyimides

Aromatic polyimides have been widely used in aerospace, electrical and electronic applications due to their outstanding thermal stability, mechanical strength at elevated temperature and electrical properties1-3. However, polyimide materials are usually difficulty to fabricate owing to their insolubility in most organic solvents and infusibility. Besides solubility, low moisture uptake of polyimide is also a major concern for microelectronics and optical applications. The present article descr…     

Crystal and Molecular Structure of 1-Phenoxy(α-methyl)acetyl-2-diethylamino-3-phenyl-1,3,2-diazaphospholidin-4-one-2-sulfide

1　INTRODUCTIONAsherbicides,thearyloxycarboxylicacidssuchas2,4-D(2,4-Dichlorophenoxyaceticacid)etc.havenotbeenusedwidelysince1970sbecauseoftheircausingenvi-ronmentalpollutionandinjuriestothecrops.Studiesonthenewtypeofherbicideshavebeendevelopinginrecentyears.Itwasreportedrecentlythatthederivativesofdiazaphospholidinoneorthecorrespondingthionespossessinterestingherbicidalactiv-ity[1～3].Itwasalsoknownthat1,4,2-diazaphospholidine-5-thione-2-oxideshasgoodselectiveherbicidalactivity[4,5],but…     

K3C60单晶膜的同步辐射光电子谱研究

在C₆₀单晶(111)解理面上制备出厚度约30 nm的K₃C₆₀单晶膜.利用同步辐射光源,在低温下(约150K)测量了样品法向发射的角分辨光电子谱.观察到K₃C₆₀导带和价带明显的色散.导带的光电子谱峰可清晰分辨出4个子峰,这些子峰的最大色散超过0.5eV,并且色散曲线与K₃C₆₀的一维无序晶体结构模型下的能带理论基本吻合,只是子带间隔差异较大.     

Determination and Temperature Dependence of Plateau Modulus for Polymerization of Propylene to Isotactic Polypropylene with Ultra-high Molecular Weight under Catalysis of Ziegler-Natta Catalyst

The viscoelastic behavior of isotactic polypropylene with ultra-high molecular weight (UHPPH) and broad molecular weight distribution(MWD), produced in the presence of Ziegler-Natta catalyst, was investigated by means of oscillatory rheometry at 180 and 200 ℃, whose loss modulus(G") plots at 180 and 200 ℃versus the natural logarithm of angular frequency(ω) present a pronounced maximum at 34.35 and 69.21 rad/s, respectively, and do not show a maximum peak at 0. 01-100 rad/s for Ziegler-Natta catalyzing ethylenepropylene random copolymerization (PPR) with a conventional molecular weight and broad MWD. The fact indicates that the high molecular weight is responsible for a maximum peak of G"(ω) vs. lnω curves for UHPPH. This makes it possible to determine the plateau modulus (G0N) of UHPPH from a certain experimental temperature G"(ω) curve directly. For UHPPH, the G0N determined to be 4. 28×105 and 3. 62×105 Pa at 180and 200 ℃, respectively, decreases with the increase of temperature and is independent of the molecular weight, which directly confirms reputation theoretical prediction that the G0N has no relation to the molecular weight.     

单光子LIF方法研究亚硝基苯266 nm光解动力学

用266nm激光解离亚硝基苯（C6H5NO）产生光解碎片NO,并利用单光子激光诱导荧光（LIF）技术（X^2Ⅱv″=0→A^2∑^+v′=0）测得初生态光解产物NO的振转光谱。根据计算所得的模拟光谱对光解碎片NO（X,v^″＝0）的转动量子数J″进行了归属,得到了量子数最大到J″＝50．5的转动能级的相对布居,这表面光解碎片NO具有较高的转动激发。提出了C6H5NO在266nm下可能的光解机理。     

Crystal Structure of Ethyl 4-benzoyl-1a,2,3,4-tetrahydro-3-methyl-1a-(4-methylphenyl)-1H-azirino〔1,2-a〕〔1,5〕 benzodiazepine-1-carboxylate(C_(28)H_(28)N_2O_3)

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Synthesis and Crystal Structure of a Mixed Cu - Cd Bim etallic Com plex ｛〔 Cu Cd(pba)( H_2 O)_3〕·2 H_2 O｝ _n

１　ＩＮＴＲＯＤＵＣＴＩＯＮＨｅｔｅｒｏｍｅｔａｌｐｏｌｙｎｕｃｌｅａｒｃｏｍｐｌｅｘｅｓｈａｖｅｂｅｅｎｔｈｅｓｕｂｊｅｃｔｏｆｍａｎｙｒｅｃｅｎｔｓｔｕｄｉｅｓｔｏｅｌｕｃｉｄａｔｅｔｈｅｍｅｃｈａｎｉｓｍｏｆｓｐｉｎｃｏｕｐｌｉｎｇｂｅｔｗｅｅｎｔｈｅｍｅｔａｌｉｏｎｓ〔１,２〕,ｍｉｍｉｃｋｉｎｇｔｈｅａｃｔｉｖｅｓｉｔｅｏｆｓｏｍｅｍｅｔａｌｅｎｚｙｍｅｓｃｏｎｔａｉｎｉｎｇｄｉｓｓｉｍｉｌａｒｍｅｔａｌｉｏｎｓ,ｓｕｃｈａｓｃｙｔｏｃｈｒｏｍｅｏｘｉｄａｓｅａｎｄｓｕｐｅｒｏｘｉ…     

苯酚在热氧化法制备的SnO2/Ti 电极上的电氧化研究

A SnO₂/Ti electrode prepared by thermal oxidation was used as the anode for galvanostatic electrolysis in acidic solution containing phenol, the time-dependances of phenol concentration,chemical oxygen demand in solution(COD)and instantaneous current efficiency were determined during electrolysis.The results show that with the SnO₂/Ti anode instead of Pt,the COD significantly decreases at the same charge passage, and average current efficiency of oxidation increases by three times The mechanism for phenol oxidation at two electrodes was discussed.