高纯氧化钪中稀土杂质的电感耦合等离子体质谱法测定

研究了用电感耦合等离子体质谱法测定高纯氧化钪中１５个稀土杂质的方法。考察了基体效应及内标的作用，采用Ｉ或Ｃｓ为内标可很好补偿基体ＳＣ的影响。方法检测限为０．０１３－０．０８５ｎｇ／ｍｌ，加料回收率为９１．２％－１０５．７％，相对标准偏 １．４％－８．１％。     

Dynamic Behavior of Rigid–Plastic Sector Plates

The paper studies the dynamic behavior of perfect rigid-plastic plates in the form of a sector with hinged or clamped sides under short-term intensive loads. Two dynamic deformation mechanisms are demonstrated. The dynamic equation is derived for each of the mechanisms. The realization conditions for the mechanisms are analyzed. Analytical expressions are derived for the ultimate (high) loads and the maximum residual deflection. Numerical examples are given     

Ideals in a perfect closure, linear growth of primary decompositions, and tight closure

This paper is concerned with tight closure in a commutative Noetherian ring of prime characteristic , and is motivated by an argument of K. E. Smith and I. Swanson that shows that, if the sequence of Frobenius powers of a proper ideal of has linear growth of primary decompositions, then tight closure (of ) `commutes with localization at the powers of a single element'. It is shown in this paper that, provided has a weak test element, linear growth of primary decompositions for other sequences of ideals of that approximate, in a certain sense, the sequence of Frobenius powers of would not only be just as good in this context, but, in the presence of a certain additional finiteness property, would actually imply that tight closure (of ) commutes with localization at an arbitrary multiplicatively closed subset of .

Work of M. Katzman on the localization problem for tight closure raised the question as to whether the union of the associated primes of the tight closures of the Frobenius powers of has only finitely many maximal members. This paper develops, through a careful analysis of the ideal theory of the perfect closure of , strategies for showing that tight closure (of a specified ideal of ) commutes with localization at an arbitrary multiplicatively closed subset of and for showing that the union of the associated primes of the tight closures of the Frobenius powers of is actually a finite set. Several applications of the strategies are presented; in most of them it was already known that tight closure commutes with localization, but the resulting affirmative answers to Katzman's question in the various situations considered are believed to be new.

     

Absorption Spectra of Gasolines in the Region 1090–1220 nm

The difference absorption spectra of different grades of gasoline (A-76, AI-92, and AI-95) with octane numbers lying within 76–85 have been investigated experimentally in comparison with hydrocarbons: isooctane, benzene, and n-heptane. The spectra obtained contain absorption bands of the CH₃, CH₂, and CH groups and supposedly of the olefin double bond. The possibility of determining the octane number of an unknown grade of gasoline by using the absorption of a measured difference spectrum at one selected wavelength is shown.     

On Pathwise Uniqueness of Stochastic Differential Equations Without Drift

We consider the stochastic differential equation: dX _t =(|X _t |)dB _t , where B is a Brownian motion and is a non-Hölder Borel function. A sufficient condition of pathwise uniqueness is given.     

On existence of undominated pure strategy Nash equilibria in anonymous nonatomic games: a generalization

In this paper, we generalize the exitence result for pure strategy Nash equilibria in anonymous nonatomic games. By working directly on integrals of pure strategies, we also generalize, for the same class of games, the existence result for undominated pure strategy Nash equilibria even though, in general, the set of pure strategy Nash equilibria may fail to be weakly compact. Received August 2001     

Valence band and band gap photoemission study of (1 1 1) In2O3 epitaxial films under interactions with oxygen, water and carbon monoxide

Synchrotron radiation ultraviolet photoemission experiments at photon energies of 150 and 49 eV were performed on an epitaxial layer of (1 1 1) In₂O₃ with good crystallinity as established by a standard scanning probe and diffraction methods. Valence band (VB) and band gap photoemission spectra were monitored under separate oxygen, water and carbon monoxide exposures (100 L) at different activation temperatures within the range utilized for chemiresistive gas sensors (160-450 °C). Large changes in photoemission response within the whole VB were observed for all gases. Regular shifts of the valence band edge relative to the Fermi energy were found under gas exposures on two kinds of surface (partially reduced or partially oxidized), and are interpreted as changes of surface potential. Treatments in oxygen resulted in upward band bending (∼0.5 eV at T = 320 °C). Regardless of activation temperature, treatments in water resulted in downward band bending, but with small changes (<0.1 eV). Reduction properties of carbon monoxide were observed only at high temperatures of T ? 370 °C. At temperatures of 160 and 250 °C unusual “oxidizing” behavior of CO was observed with upward band bending of ∼0.7 eV (160 °C). Oxidizing and reducing effects of the gas interactions with the (1 1 1) In₂O₃ surface in all cases were accompanied by a corresponding behavior, i.e., a decrease or increase in photoemission response from so-called defect states in the band gap near the top of the valence band. The increases of photoemission within a band gap with maxima at binding energies (BE) of 0.4 (O₂-induced peak) and 1.0 eV (CO-induced peak) were, respectively, found for interactions with O₂ and CO for low temperatures (T = 160 and 250 °C). These responses were ascribed to acceptor-like electronic levels of O₂ and CO chemisorption states, respectively. A definite split of the top VB peak (BE ∼ 4.0 eV) was found under CO dosing at 160 °C. Established knowledge of the CO interaction with the (1 1 1) In₂O₃ surface explains earlier revealed acceptor-like behavior of In₂O₃ film conductivity during CO detection at operational temperatures lower than 250 °C through the formation of acceptor-like electronic levels of adsorbed CO molecules.     

Gas-chromatographic method of evaluation ofn-alkanol ability for self-association in pure liquid

The values of the gas-chromatographic indicator reflecting the capacity of analytes for self-association in pure liquids, δT _b.p., were estimated for C₁–C₉ and C₁₁ n-alkanols by capillary gas chromatography on a nonpolar stationary phase under isothermal conditions. The δT _b.p. values ofn-alkanols, found as the difference between the boiling points measured directly and those calculated from GC data, are correlated with thermodynamic characteristics of the formation ofn-alkanol associates in pure liquids. Usingn-alkanols as analytes with insignificant temperature increments of the retention indices, it was shown that the δT _b.p. values can be determined under conditions used in gas chromatography with temperature programming. In this way a single chromatographic run can be used to compare the capacities for self-association of analytes boiling over a wide temperature range. The C₂–C₉ n-alkanethiols, which are not associated in neat liquids, have negative δT _b.p. values. An interpretation of this finding is proposed. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 315–318 February, 2000.     

Annealing effect in glass woven fabric composites,Part II. Bending properties

Effects of annealing on bending properties of composites reinforced with plain glass woven fabrics that were treated with different concentrations of silane coupling agent were investigated in this paper. Bending strength increased by annealing in the specimen treated with lower silane concentration. Higher annealing temperature in a range from 80°C to 150°C led to higher bending strength. Then, the fracture mode changed from a micro-crack type (low strength type) to a branched matrix crack type (high strength type) by annealing.