Development and Performance Characteristics of a Capillary Dosage Unit with in Situ Weight Sensor for the Preparation of Known Amounts of Gaseous Voc's in Air

Abstract

This paper describes the design, performance and operation of a home-made capillary dosage unit with in situ weight sensor. This continuous injection technique is developed to produce dynamic gas phase calibration mixtures of VOC's in a diluent gas at occupational hygiene levels. A new advance in the technique allows the calculation of the amounts of pollutants emitted into the carrier gas, directly from the gravimetric measurements.

This is achieved by a built-in weight sensor which is monitored without interfering with the injection process. The survey of the capillary dosage unit(s) is managed by a microcomputer which automatically lists the amounts of pollutants introduced into the diluent gas. The capillary dosage technique thus becomes related directly to a primary standard.

The homogeneity and stability of the test gas generated is shown to be better than 1% relative standard deviation over periods of up to 24 hours. The VOC concentrations in the manifold are known with a total uncertainty of between 2 and 3%SS.     

差示扫描量热仪检定用标准物质的研制

介绍了四种差示扫描量热仪温度标准物质的研制过程及所取得的研究成果。     

Geometric methods for nonlinear many-body quantum systems

Geometric techniques have played an important role in the seventies, for the study of the spectrum of many-body Schrödinger operators. In this paper we provide a formalism which also allows to study nonlinear systems. We start by defining a weak topology on many-body states, which appropriately describes the physical behavior of the system in the case of lack of compactness, that is when some particles are lost at infinity. We provide several important properties of this topology and use them to write a simple proof of the famous HVZ theorem in the repulsive case. In the second step we recall the method of geometric localization in Fock space as proposed by Dereziński and Gérard, and we relate this tool to our weak topology. We then provide several applications. We start by studying the so-called finite-rank approximation which consists in imposing that the many-body wavefunction can be expanded using finitely many one-body functions. We thereby emphasize geometric properties of Hartree-Fock states and prove nonlinear versions of the HVZ theorem, in the spirit of works of Friesecke. In the last section we study translation-invariant many-body systems comprising a nonlinear term, which effectively describes the interactions with a second system. As an example, we prove the existence of the multi-polaron in the Pekar-Tomasevich approximation, for certain values of the coupling constant.     

A note on matrics with given diagonal entries

Mirsky and Erdos and Mine have given criteria for the existence of a non-negative square matrix with prescribed diagonal entries and row and column sums; it is shown that this result follows from the supply-demand theorem for flows in networks.     

Exhaustive determination of (1023, 511, 255)-cyclic difference sets

An exhaustive search for (1023, 511, 255)-cyclic difference sets has been conducted. A total of 10 non-equivalent (1023, 511, 255)-cyclic difference sets have been found, all of which are members of previously known or conjectured infinite families. A fast and effective autocorrelation test method was utilized that can also facilitate the testing of longer sequences.

     

High‐performance liquid chromatographic method for the quantification of Mitragyna inermis alkaloids in order to perform pharmacokinetic studies

In Africa, Mitragyna inermis (Willd.) O. Kuntze (Rubiaceae) is commonly used in traditional medicine to treat malaria. Antimalarial activity is mostly due to the hydromethanolic extract of M. inermis leaves and especially to the main alkaloids, uncarine D and isorhynchophilline. In the present study, we describe for the first time an HPLC method for the simultaneous quantification of uncarine D and isorhynchophylline in biological matrices. SPE was used to extract the components and the internal standard naphthalene from human and pig plasma samples. Chromatographic separation was performed on a C‐18 reversed column at a flow rate of 1 mL/min, using methanol–phosphate buffer (10:90, pH 7), as a mobile phase. Good linearity was observed over the concentration ranges of 0.0662–3.31 μg/mL for uncarine D and 0.0476–2.38 μg/mL for isorynchophylline. The precision was less than 12% and the accuracy was from 86 to 107% without any discrepancy between the two species. Uncarine D and isorhynchophylline recoveries were over 80%. These results allowed the quantification of both uncarine D and isorhynchophylline in pig plasma after intravenous administration of M. inermis extract.     

直径≤d的对称本原矩阵类的指数集

证明了直径≤[d≤d[n/2]]的全体n阶对称本原矩阵类的本原指数集是Ed={1,2,…,2d}.     

电感耦合等离子体质谱法测定高纯氧化钇

报道了高纯氧化钇中３０种痕量稀土和非稀土杂质元素的电感耦合等离子体质谱测定方法。考察了谱干扰及基体效应，采用Ｇａ内标能较好地补偿基体钇的影响。方法检出限为０．０１３￣４．１μｇ／Ｌ。方法简便，快速，灵敏。     

一种新的变权向量及其应用

在对常权综合和变权综合进行分析的基础上,结合变权的初衷,构造了一个新的变权向量用于变权综合.构造的变权满足变权向量的公理条件和加型综合函数的定义,运用这个变权公式进行加权综合分析时,综合决策值等于加权均值减去加权方差的一半,具有很好的实际意义.     

二、三阶可逆矩阵可以相似对角化的几何条件

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