Re-study of Nucleon Pole Contribution in J/

[1]V.D.Burkert,Phys.Lett.B 72 (1997) 109. [2]S.Capstick and W.Roberts,Prog.Part.Nucl.Phys.45 (2000) S241,and references therein. [3]B.S.Zou,Nucl.Phys.A 675 (2000) 167c; B.S.Zou,Nucl.Phys.A 684 (2001) 330; BES Collaboration (J.Z.Bai,et al.) Phys.Lett.B 510 (2001) 75; BES Collaboration (M.Ablikim,et al.),hep-ex/0405030. [4]R.Sinha and Susumu Okubo,Phys.Rev.D 30 (1984)2333. [5]W.H.Liang,P.N.Shen,B.S.Zou,and A.Faessler,Euro.Phys.J A 21 (2004) 487. [6]Particle Data Group,Euro.Phys.J.C 15 (2000) 1. [7]K.Tsushima,A.Sibrtsev,and A.W.Thomas,Phys.Lett.B 390 (1997) 29. [8]J.Kogut,Rev.Mod.Phys.51 (1979) 659; Rev.Mod.Phys.55 (1983) 775. [9]Q.Haider and L.C.Liu,J.Phys.G 22 (1996) 1187; L.C.Liu and W.X.Ma,J.Phys.G 26 (2000) L59. [10]V.G.J.Stoks,R.A.M.Klomp,C.P.F.Terheggen,and J.J.de Swart,Phys.Rev.C 49 (1994) 2950. [11]H.Haberzettl,C.Bennhold,T.Mart,and T.Feuster,Phys.Rev.C 58 (1998) R40. [12]Y.Oh,A.I.Titov,and T.-S.H.Lee,Phys.Rev.C 63(2001) 25201.     

Electrochemical investigation of redox thermodynamics of immobilized myoglobin: ionic and ligation effects

In this study, we investigated redox thermodynamics of myoglobin as well as the ionic (phosphate ions) and ligation (imidazole) effects via a dynamic electrochemical approach. We employed a previously established system that features nonmediated, direct electrochemistry of myoglobin and myoglobin in an immobilized state (i.e., diffusionless electrochemistry). Thermodynamics parameters were obtained by measuring redox potential (E degrees ') of myoglobin at varied temperature (T), in the presence and in the absence of specific ions or axial ligands. As a step further, we evaluated contributions from allosteric effect and axial iron ligation by partitioning E degrees ' changes into entropic and enthalpic terms. Compensation phenomena between the entropic and enthalpic changes were observed in all these cases. On the basis of these studies, we also correlated these phenomena to possible structural variations.     

Linear Chemical Potential Dependence of Two-Quark Condensate

By differentiating the inverse dressed quark propagator at finite chemical potential μ with respect to μ, the linear response of the dressed quark propagator to the chemical potential can be obtained. From this we extract a modelindependent formula for the linear chemical potential dependence of the in-medium two-quark condensate and show by two independent methods (explicit calculation and Lorentz covariance arguments) that the first-order contribution in μto the in-medium two-quark condensate vanishes identically. Therefore if one wants to study the in-medium two-quark condensate one should expand to at least the second order in the chemical potential μ.     

SIMULATION OF OCCUPATION FUNCTION FOR THERMALLY STIMULATED CONDUCTIVITY IN AMORPHOUS SEMICONDUCTORS

The occupation functions for the general condition f(E,T), for the high field approx-imation (HTSC) f_H(E,T) and for the steady state photoconductivity (SSPC) f_P(E,T) in the thermally stimulated conductivity (TSC) of amorphous semiconductors have been inves-tigated. It was found that the occupation function f(E,T) in TSC is in excellent agreement with the occupation function in SSPC f_P(E,T) under the condition of σ_TSC(T) = σ_P(T).There is a large difference between f_P(E,T) and f_H(E,T), which can be much reduced by introducing an effective attempt to escape frequency ν_eff in the calculation of f_H (E, T). The results show that the mobility-lifetime product (μτ) in TSC obtained from SSPC measure-ments under the above condition is valid. For high field approximation TSC, the simulated ν_eff is found to be temperature dependent.     

链酚胺型配体锌(Ⅱ)配合物模拟碳酸酐酶研究

合成了酚胺型链状配体,N,N'-二(2-羟基苄基)丙二胺(H~2L)及其Zn(Ⅱ)配合物(ZnL),通过元素分析、IR和^1HNRM等手段进行了表征。采用pH电位滴定法,在25℃±0.1℃,I=0.1mol·dm^-^3(KNO~3)条件下,测定了配体的质子化常数以及配体与金属离子Zn(Ⅱ)配位反应平衡常数。讨论了配体与金属离子Zn(Ⅱ)的配位情况,得到了配位酚羟基的解离常数。运用分光光度法,在25℃±0.1℃,I=0.1mol·dm^-^3(KNO~3)条件下,在pH=5.5～9.0(50mmol·dm^-^3缓冲溶液)范围内,研究了配合物作为碳酸酐酶模拟物催化对-硝基苯酚乙酸酯(NA)水解动力学,得到了NA酯水解的配合物催化速率常数k~N~P。实验结果表明,ZnHL^+的配位酚羟基的解离常数pK~a为6.83;催化速率常数k~N~P与pH之间不存在Sigmoidal型曲线关系,而是在pH值中性附近有最大值,ZnHL^+对NA酯水解有很好的催化效果,并且采取双重催化机理,是碳酸酐酶很好的模拟物。     

泡沫铝负载钌基催化剂应用于N2O的低温催化分解研究

将导热性能良好的泡沫铝作为载体,羰基钌为前驱体制备了一系列不同形态的钌基催化剂应用于N2O的低温催化分解研究.采用XRD、XPS、SEM、TEM、BET、H2-TPR等方法对催化剂进行了表征,于石英管固定床反应器上对催化剂性能进行了评价.重点考察了泡沫铝作为催化剂载体的可行性、载体的处理方法对催化剂活性的影响以及RuO2、Ru、Ru3(CO)12所表现出的活性差异.结果表明:泡沫铝作为催化剂载体,能够促进N2O的催化分解;泡沫铝经H2O2处理有利于提高其对活性中心的附着力,提高催化活性;N2O浓度为1%,Ru负载量为0.3%,活性中心分别为Ru3(CO)12、Ru、RuO2时,N2O完全转化温度依次为285、380和415℃;活性较高的Ru3(CO)12/泡沫铝催化剂在长时间作用后活性组分转变为RuO2.     

电化学噪声测量分析系统设计与实现

根据电化学噪声原理,利用微机技术设计实现了电化学噪声测量分析系统。该系统具有高灵敏度,自动选择量程,多回路自动测量,可调整采样参数等功能,并在时／频域内对所测量的电化学噪声进行分析。     

Synthesis,Crystal Structure and Biological Activity of 2-(3,4-Dichloroisothiazol-5-yl)-4-(trifluoromethyl)-4,5-dihydrothiazol-4-yl-3-methylbenzoate

The title compound diethyl 2-(3,4-dichloroisothiazol-5-yl)-4-(trifluoromethyl)-4,5-dihydrothiazol-4-yl-3-methylbenzoate(C15H9Cl2F3N2O2S2, Mr = 441.26) was prepared from methyl 3,4-dichloroisothiazole-5-carboxylate as the starting material by four steps of reaction. Its structure was characterized by IR, 1H-NMR, 13C-NMR, EA and single-crystal X-ray diffraction. The crystal of the title compound belongs to the monoclinic system, space group P21/c with a = 8.8437(18), b = 16.128(3), c = 12.305(3), β = 91.68(3)o, V = 1754.4(6) 3, Z = 4, Dc = 1.671 g/cm3, μ(Mo Ka) = 0.71073 mm-1, F(000) = 888, R = 0.0384 and w R = 0.0778. Weak π-π interactions occur between the isothiazole rings and phenyl rings of adjacent molecules to form a one-dimensional chain and stabilize the crystal structure. Bioassay indicates that the title compound has good activity against the fungi and TMV tested.     

Recognizing ortho-, meta- or para-positional isomers of S-methyl methoxylphenylmethylenehydrazine dithiocarboxylates by ESI-MS2: The positional effect of the methoxyl substituent

The dissociation chemistry of the ortho-, meta- or para-isomers of protonated S-methyl methoxyl- (or chloro-) benzenylmethylenehydrazine dithiocarboxylate, RPhCHN–NHC(S)–SCH₃ (R = MeO– or Cl–), has been investigated by collision induced dissociation experiments and DFT theoretical calculations. The three methoxyl-substituted isomers were easily differentiated according to the different abundance of the characteristic ion at m/z 136, resulting from the varying reactivity of the (NSC)SCH₃ elimination. This fragmentation is triggered by the positive charge upon protonation on the imine N2. Relative to the meta isomer, the positive charge on N2 in the para isomer is dispersed due to the electron donating resonance of the methoxyl group, which leads to higher energy barrier in the dissociation reaction and the less abundant product ion (m/z 136) in the MS/MS. (NSC)SCH₃ elimination of the ortho- isomer is further suppressed due to both the resonance effect and the “ortho effect” (an intramolecular hydrogen bond), with much higher energy barrier and extremely lower abundance of the fragment ion (m/z 136, 0.4%). The chloro substituted isomers, however, are short of the above positional effects due to the weak electronic effect of the substituent, and share the similar tandem mass spectrum.