光度法对不同土地利用类型河流在不同水期氮磷分布特性及定量源解析研究

氮和磷是水环境生物生长和繁殖必须的营养成分,影响水体初级生产力的水平,且水体富营养化水平与氮磷形态密切相关,随着水体环境的改变,沉积物会向水体释放氮磷,造成二次污染。同时,对外源氮磷污染来源的贡献进行定量识别,可有效管理和控制水体氮磷污染负荷。毗河和石亭江是沱江的重要支流,影响着长江母亲河的水质。采用钼锑抗分光光度法和连续提取法研究在枯水期和丰水期毗河和石亭江水体和表层沉积物中总氮(TN)、总磷(TP)及各形态氮磷的分布特性,对比不同土地利用类型河流氮磷行为特性及释放风险,并采用Multiple Linear Regression of the Absolute Principal Component Scores(APCS-MLR)受体模型进行氮磷污染源的识别和量化。研究结果表明：(1)研究区水体和表层沉积物中氮磷均处于不同程度的污染水平,水体枯水期TP的主要贡献者是颗粒态无机磷(PIP)和颗粒态有机磷(POP),而丰水期却是颗粒态无机磷(PIP)和溶解态无机磷(DIP),两水期水体中TN的主要贡献者是硝态氮(NO^-₃-N)和有机氮(ON)...     

Distribution of Platinum and Palladium between Dissolved,Nanoparticulate, and Microparticulate Fractions of Road Dust

Ageing processes of vehicle catalytic converters inevitably lead to the release of Pt and Pd into the environment, road dust being the main sink. Though Pt and Pd are contained in catalytic converters in nanoparticulate metallic form, under environmental conditions, they can be transformed into toxic dissolved species. In the present work, the distribution of Pt and Pd between dissolved, nanoparticulate, and microparticulate fractions of Moscow road dust is assessed. The total concentrations of Pt and Pd in dust vary in the ranges 9–142 ng (mean 35) and 155–456 (mean 235) ng g⁻¹, respectively. The nanoparticulate and dissolved species of Pt and Pd in dust were studied using single particle inductively coupled plasma mass spectrometry. The median sizes of nanoparticulate Pt and Pd were 7 and 13 nm, respectively. The nanoparticulate fraction of Pt and Pd in Moscow dust is only about 1.6–1.8%. The average contents of dissolved fraction of Pt and Pd are 10.4% and 4.1%, respectively. The major fractions of Pt and Pd (88–94%) in road dust are associated with microparticles. Although the microparticulate fractions of Pt and Pd are relatively stable, they may become dissolved under changing environmental conditions and, hence, transformed into toxic species.     

On the Statistics of Partial Quotients of Finite Continued Fractions

We refine the remainder estimate in the asymptotic formula, earlier obtained in a joint paper with V. A. Bykovskii, for Arnold's problem about Gauss-Kuzmin statistics.     

交换半群环的分式环

设含幺交换环Ｒ对其乘法子集Ｔ的分式环为ＲＴ，交换幺半群Ｓ在其子半群∑处局部化为Ｓ∑本文证明了Ｒ［Ｓ］对于Ａ的分环式环Ｒ［Ｓ］ＡＭ 构于半群环ＲＴ［Ｓ∑］。     

矩阵连分式序列的收敛性

本文研究了矩阵连分式的性质，获得了关于矩阵连分式序列收敛性的一些结果．     

Rook numbers and the normal ordering problem

For an element w in the Weyl algebra generated by D and U with relation DU=UD+1, the normally ordered form is w=∑c_i,jUⁱD^j. We demonstrate that the normal order coefficients c_i,j of a word w are rook numbers on a Ferrers board. We use this interpretation to give a new proof of the rook factorization theorem, which we use to provide an explicit formula for the coefficients c_i,j. We calculate the Weyl binomial coefficients: normal order coefficients of the element (D+U)ⁿ in the Weyl algebra. We extend these results to the q-analogue of the Weyl algebra. We discuss further generalizations using i-rook numbers.     

On the Approximation of Irrationals by Rationals

Let ξ be a real irrational number, and a ≧ 0, b ≧ 0, s > 1 be integers. A theorem of S. UCHIYAMA states that there are infinitely many pairs of integers u and v ≠ 0 such that OVBARξ?u/vOVBAR ≤ s²/4v² and u ? a, v ? b mod s, provided that it is not a ? 6 ? 0 mod s. It is shown that this result is best-possible for all integers s > 1.     

Continued fraction of e2 with confluent hypergeometric functions

The tanh-type, tan-type, and e-type Hurwitz continued fractions have been generalized by the author. In this paper, we study a generalized form of e²-type Hurwitz continued fractions by using confluent hypergeometric functions. We also obtain a similar type of Tasoev continued fractions. Published in Lietuvos Matematikos Rinkinys, Vol. 46, No. 4, pp. 513–531, October–December, 2006.     

左分式半群的几个性质

讨论了若干半群类在取左分式半群下的封闭性，给出了关于左发式半群的一个同构定理。     

Difference equations in statistical mechanics. I. Cluster statistics models

A review and some new results are presented for several cluster statistics models, solutions of which can be reduced to difference equations. Mathematical techniques suitable for solving these equations are surveyed.