微分脉冲溶出伏安法同时测定食品中的锌铁锰

在1％乙二胺-0．1mol／L酒石酸钠-pH11．82 Britton—Robinson缓冲溶液体系中用微分脉冲溶出伏安法同时测定锌、铁、锰三种微量元素。它们的峰电位分别为-1184，-1392和-1456mV(vs．Ag/AgCl)；线性范围分别为：0.001—0.015，0．005—0．05和0．04—0．7μg／mL，最低检出浓度分别为0．0007，0．0014和0．0193μg／mL。本法操作简便、准确、灵敏度较高，用于食品中这三种元素的分析，结果令人满意。     

Mechanism of Interaction of γ-Halogenated Salts of Pyrylium and Benzopyrylium with Aromatic Amines

Stoichiometry and kinetics of reactions of 2,6-diphenyl-4-chloropyrylium, 4-chloroflavylium, 4-bromoflavylium, and 4-iodoflavylium perchlorates with nucleophiles N,N-dimethylaniline and n-phenylenediamine are studied using cyclic voltammetry and spectroscopy. Nucleophilic substitution in these compounds proceeds via the formation of a charge-transfer complex, which converts into a radical ion pair as a result of the electron transfer. Heterolytic clevage of the C–Hal bond occurs at the stage of pyranyl (flavanyl) radical.     

Enthalpies of sorption of linear hydrocarbons (C2–C8) and chloroderivatives of methane and ethylene on the surface of hydrotalcite

Differential molar adsorption enthalpies (DMAE) were determined by gas chromatographic measurements of specific retention volume of vapors on the surface of two forms of Mg–Al hydrotalcite. A linear dependence of the DMAE on the number of the carbon atoms in hydrocarbons was observed for both form of hydrotalcite. The dependence of the differential molar adsorption enthalpies on the number of chlorine atoms in organic molecules is discussed. A linear dependence of DMAE on the molecular weight of chloroderivatives of methane and ethylene on the basic form in an order monochloromethane < dichloromethane < trichloromethane or vinylidene chloride < 1,1-dichloroethylene < trichloroethylene was found.     

ON OPTIMAL BACKWARD PERTURBATION ANALYSIS FOR THE LINEAR SYSTEM WITH BLOCK CYCLIC COEFFICIENT MATRIX

Based on the block style spectral decomposition, this paper deals with the optimal backward perturbation analysis for the linear system with block cyclic coefficient matrix.     

60keV质子辐照对TiNi记忆合金薄膜马氏体相变的影响

 利用磁控溅射的方法在氧化后的单晶Si基片上制备了TiNi形状记忆合金薄膜，利用示差扫描量热法和原位X射线衍射研究了薄膜的马氏体相变特征。通过60keV质子注入（辐照）薄膜样品研究了H+离子对合金薄膜马氏体相变特征的影响，结果表明氢离子注入后引起了马氏体相变开始Ms和结束点Mf以及逆马氏体相变开始As和结束温度Af的下降，而对R相变开始Rs和结束温度Rf影响不大。掠入射X射线衍射表明H+离子注入后有氢化物形成。H⁺离子注入形成的氢化物是引起相变点的变化的主要因素。     

Differential FBG sensor for temperature-compensated high-pressure (or displacement) measurement

A differential fiber Bragg grating (FBG) sensor with a free active element bulk-modulus for high-pressure (or displacement) measurement is presented. Based on the differential measurement method and an isosceles triangle cantilever structure, problems of cross-sensitivity and chirped signal in FBG sensor are improved both theoretically and experimentally. Preliminary experiments indicate that temperature-compensated measurement results agree well with the theoretical analysis. Displacement measurement sensitivity is 1.75 pm/μm, and the estimated pressure measurement resolution can reach 0.27 MPa in case the wavelength shift measurement resolution is 0.01 nm.     

Surjectivity and fixed points of relaxed dissipative multifunctions. Differential inclusions approach

One from the most important properties of accretive and monotone operators is the existence of zeros and surjectivity. In the paper we introduce relaxed variants of dissipative, accretive and monotone operators. Using essentially the properties of the solution set of appropriate differential inclusions we study the existence of zeros of such operators. As corollaries the existence of fixed points of relaxed contractive and relaxed nonexpansive multifunctions are obtained.     

Cyclo[(6-amino-6-deoxy-d-galactonic acid)4]: a new class of carbopeptoid-cyclodextrin

The formation of the 28-membered ring cyclo[(6-amino-6-deoxy-d-galactonic acid)₄] by cyclisation of a protected open chain fully hydroxylated nylon 6 linear tetramer in modest yield provides the first example of a new class of carbopeptoid-cyclodextrin.     

Spectral Analysis of Powers of the Operator (Vf)(x)=q(x)∫0 xw(t)f(t),dt

Mathematical Notes -