流动注射分析法响应曲线的方差和样品分散

根据串联釜模型，考察了响应曲线的方差与各变量（反应管长，载流流速和进样体积）间的关系以及方差与相应分散系数的关系。只有在载流流速和进样体积一定时，才能以方差表征分散系数。     

金属性Zintl相化合物RE_3Cu_3Sb_4(RE=Nd,Sm,Tb,Dy,Ho)的合成、结构及成键特性

用电弧熔炼方法合成了化合物ＲＥ３Ｃｕ３Ｓｂ４（ＲＥ＝ Ｎｄ,Ｓｍ ,Ｔｂ,Ｄｙ,Ｈｏ）, 采用粉末Ｘ射线衍射方法测定了其晶体结构。化合物属立方晶系,Ｙ３Ａｕ３Ｓｂ４ 类型, 空间群Ｉ４３ｄ（Ｎｏ．２２０）,皮尔森玛ｃＩ４０。晶胞参数：Ｎｄ３Ｃｕ３Ｓｂ４ ：ａ＝０．９６７４９（１） ｎｍ, Ｖ＝０．９０５６１（３） ｎｍ３;Ｓｍ３Ｃｕ３Ｓｂ４：ａ＝ －０．９６１４５（１） ｎｍ ,Ｖ＝０．８８８７５（３） ｎｍ３ ;Ｔｂ３Ｃｕ３Ｓｂ４： ａ＝０．９５３６２（１） ｎｍ , Ｖ＝ ０．８６７２１（３）ｎｍ３;Ｄｙ３Ｃｕ３Ｓｂ４： ａ＝０．９５０８８（１） ｎｍ , Ｖ＝０．８５９７５（３） ｎｍ３;Ｈｏ３Ｃｕ３Ｓｂ４ ： ａ＝０．９４８８（２） ｎｍ , Ｖ＝０．８５４１（５） ｎｍ３。每个单胞中包含４ 个化合式量。此结构中,Ｃｕ 原子均处于Ｓｂ 原子所形成的配位四面体中心, 这些共价结合的配位四面体通过共顶最终联接形成三维ＣｕＳｂ 网络,稀土原子则散布在网络之间的空隙中。化合物电荷平衡结构式可表示为ＲＥ３＋３ Ｃｕ１＋３ Ｓｂ３－４ , 化合物具有导电性, 为金属性Ｚｉｎｔｌ 相。原子成键具有典型过渡性。原子的“配位数”遵从配位环境规律。化合物的     

流动注射分析系统混合釜数的测量

根据串联釜模型，提出一个计算流动注分析系统混合釜数的关系式，此关系式为１＝１１．０９（ｔｐ／Ｗ０．２５）＾２＋１．１５式中，ａ为系统混合釜数，Ｗ０．２５为由系统所得响应曲线峰高１．４处的峰宽，ｔｐ为响应曲线起峰点至极大处所经历的时间。     

流动注射分析中提高线性范围的一种方法

经证明，在流动注射分析中使用光度检测器和进样体积一定时，下式成立：ｃ＝ａ＋ｂｌｎ（１－ｈ／ｈ０）。式中ｃ为试样浓度，ａ和ｂ为与实验条件有关的系数，ｈ和ｈ０分别为试样峰和定态时的峰高。ｈ０几乎不随浓度增加而变化。应用此式可提高测定的线性范围，进行较高浓度试样的测定。     

高温高压下三相机械高压搅拌釜中气体质量传递特性的研究

本文采用气体间歇物理吸收技术，在一立升的表面进气式高压机械搅拌釜中，在温度（３７３－５７３Ｋ）、气体压力（１－４ＭＰａ）和混合速度（１３．３Ｈｚ）的实验条件下，测定了Ｈ２、ＣＯ在液体石蜡、正二十八烷烃、ＦＴ３００蜡中的体积传质系数（ｋ１ａ），实验中发现：两种气体在三种液体介质中的体积传质系数胡温度手升高而增加，随气体分压的增加而增加。在同一种液体介质中，Ｈ２和     

硫堇衍生化自组装膜修饰金电极的电化学性质及其对抗坏血…

将硫堇共价键合到自组装在金电极表面的半胱胺单分子层上，制成了衍生化自组装单分子膜修饰电极，并用电化学方法研究了它的电化学性质，循环伏安图显示其在ｐＨ＝７．７的磷酸盐缓冲液中，于－０．４５～＋０．５０Ｖ（ｖｓ．ＳＣＥ）范围内有２对氧化还原峰，峰电位分别为Ｅｐａ＝２１４ｍＶ，Ｅｐｃ＝８２ｍＶ，Ｅ＾２ｐａ＝－７５ｍＶ，Ｅ＾２ｐｃ－－１６０ｍＶ（ｖｓ．ＳＣＥ），ｐＨ在５．０～９．０范围内，峰１有２个质子参     

希土化合物对离体巨噬细胞的影响

本文应用细胞培养法和单细胞阳离子测定系统研究了希土化合物以地巨噬细胞的影响，结果表明，在培养介质中ＳｍＣｌ３和Ｙｃｌ３的浓度大于１ｍｍｏｌ．ｄｍ＾－３时，有明显的细胞毒性，Ｙｃｌ３的细胞毒性大于ＳｍＣｌ３，ＳｍＣｌ３和ＹＣｌ３的细胞毒性明显大于Ｓｍ（Ａｌａ）３Ｃｌ３和Ｙ（Ａｌａ）２Ｃｌ３。希土化合物的作用使细胞（Ｃａ＾２＋ｉ）升高；毒性越大，Ｃａ＾２＋ｉ升高越甚。低浓度Ｓｍ＾３＋和Ｙ６３＋对细胞膜     

砷锑钼三元杂多酸光化学光度法测定痕量砷

砷锑钼三元杂多酸光化学分光光度法是测定０ ．０４ ～１ ．０ ｍ ｇ／ Ｌ 砷的新方法。在０ ．１２ ｍｏｌ／ Ｌ Ｈ２ Ｓ Ｏ４２ ．０ ×１０ － ４ ｍ ｏｌ／ Ｌ Ｓｂ（ Ⅲ）２ ．０ ×－ ３ ｍ ｏｌ／ Ｌ Ｍｏ（ Ⅵ）４ ％ （ Ｖ／ Ｖ） 甲醇介质中, Ａｓ（ Ⅲ） 、 Ｓｂ（ Ⅲ） 、 Ｍｏ（ Ⅵ） 形成的三元杂多酸被紫外光还原生成三元杂多蓝（λｍ ａ ｘ ＝ ７８０ ｎｍ ） 。实验结果表明,方法具有灵敏度高,选择性好,操作简便等特点。     

聚硫堇修饰微带金电极的性质及对NADH的催化氧化

报道了硫堇在微带金电极上的电化学聚合过程，用红外光谱对聚硫堇进行了表征；研究了聚硫堇的电化学性质，发现聚硫堇在＋０．５～－０．７Ｖ（ｖｓ．ＳＣＥ）电位范围内有两对氧化还原峰，峰电位分别为：Ｅ＝－０．０３Ｖ、Ｅ＝０．０５Ｖ，Ｅ＝－０．２４Ｖ、Ｅ＝－０．１７Ｖ（ｖｓ．ＳＣＥ）。它们的式量电位Ｅ~（ｏ＇）随ｐＨ而变化，在弱酸性溶液中，Ｅ~（ｏ＇）／ｐＨ为－２９ｍＶ／ｐＨ（２５℃）；而在弱碱性溶液中则为－５６ｍＶ／ｐＨ。聚硫堇修饰微带金电极对ＮＡＤＨ的氧化具有催化作用，文中对电催化过程进行了探讨。     

Effect of Addition Groups on the Redox Properties of Fullerenes

采用循环伏安法和微分脉冲伏安法对比地研究了包括五种Ｃ６０的衍生物及四种Ｃ７０的衍生物的电化学性质．结果表明，推电子基团的引入使得富勒烯的氧化还原电位负移，这种负移的程度与加成基团的性质、个数和富勒烯的性质有关．对于Ｃ６０和Ｃ７０的单加成产物，负移的范围是０．０８～０．２０Ｖ．而对于Ｃ６０的双加成和三加成产物负移的范围分别为０．３０～０．３２Ｖ和０．５３～０．５８Ｖ．同时由于电位的负移大部分衍生物在低于＋１．５Ｖ（ｖｓ．ＳＣＥ）观察到了氧化峰，而Ｃ６０和Ｃ７０本身的氧化高达＋１．７Ｖ（ｖｓ．ＳＣＥ）．特别是对于Ｃ７０的双加成产物在＋０．４５Ｖ（ｖｓ．ＳＣＥ）出现了一个不可逆氧化峰，但是，对于同样加成基团的Ｃ６０双加成产物的氧化却在＋０．９０Ｖ（ｖｓ．ＳＣＥ），说明由于推电子基团的双加成引入，明显改变了Ｃ７０的电负性．     

Design of an interface to allow microfluidic electrophoresis chips to drink from the fire hose of the external environment

An interface design is presented that facilitates automated sample introduction into an electrokinetic microchip, without perturbing the liquids within the microfluidic device. The design utilizes an interface flow channel with a volume flow resistance that is 0.54-4.1 x 10(6) times lower than the volume flow resistance of the electrokinetic fluid manifold used for mixing, reaction, separation, and analysis. A channel, 300 microm deep, 1 mm wide and 15-20 mm long, was etched in glass substrates to create the sample introduction channel (SIC) for a manifold of electrokinetic flow channels in the range of 10-13 microm depth and 36-275 microm width. Volume flow rates of up to 1 mL/min were pumped through the SIC without perturbing the solutions within the electrokinetic channel manifold. Calculations support this observation, suggesting a leakage flow to electroosmotic flow ratio of 0.1:1% in the electrokinetic channels, arising from 66-700 microL/min pressure-driven flow rates in the SIC. Peak heights for capillary electrophoresis separations in the electrokinetic flow manifold showed no dependence on whether the SIC pump was on or off. On-chip mixing, reaction and separation of anti-ovalbumin and ovalbumin could be performed with good quantitative results, independent of the SIC pump operation. Reproducibility of injection performance, estimated from peak height variations, ranged from 1.5-4%, depending upon the device design and the sample composition.     

Generation of time-dependent concentration profiles using a reduced-size continuous-flow manifold

A computer-controlled manifold allowing the automatic generation of concentration profiles is described. For this purpose, the sample or standard solution is placed inside a semi-closed loop to which diluent is incorporated at a given flow rate, while the solution is removed at the same flow rate and directed towards the detector. The flow manifold, which works in a similar way to the tank model, includes a membrane micropump to recirculate the solution in the semi-closed loop. For simplicity purposes in the assessment of the system, a flame atomic absorption spectrometer is used for both withdrawing liquid and detection, although the basic idea can easily be extended to other detectors. The experimental data, verified by measuring the calcium, magnesium, sodium and potassium contents of some soft drinks demonstrate that the approach is reliable and may be a basis for developing portable instruments of reduced-size.     

Development of the continuously variable volume reactor for flow injection analysis: Part 1. Design, capabilities and testing

A new apparatus for mixing sample and reagent in flow injection analysis (FIA) is described. The continuously variable volume reactor (CVVR) replaces the conventional mixing coil in a flow injection (FI) manifold to provide mixing and dilution. A linear actuator motor allows control of the chamber volume via LabVIEW software. The chamber volume can be incremented in steps of 1 μl over the range 68-1704 μl. In addition, the chamber has an integral variable-speed stirring unit that is also under computer control. Experiments were performed to evaluate the dispersion characteristics of this new device, evaluate the volume reproducibility, and understand the mixing characteristics. Use of the chamber is shown in the determination of iron(II) in pond water, and in NIST SRM 1643d with excellent results and a detection limit of 3.7 μg/l iron(II). Advantages of the CVVR and future research activities using the device are discussed.     

On the Statistical Mechanics of Non-Hamiltonian Systems: The Generalized Liouville Equation, Entropy, and Time-Dependent Metrics

Several questions in the statistical mechanics of non-Hamiltonian systems are discussed. The theory of differential forms on the phase space manifold is applied to provide a fully covariant formulation of the generalized Liouville equation. The properties of invariant volume elements are considered, and the nonexistence in general of smooth invariant measures noted. The time evolution of the generalized Gibbs entropy associated with a given choice of volume form is studied, and conditions under which the entropy is constant are discussed. For non-Hamiltonian systems on manifolds with a metric tensor compatible with the flow, it is shown that the associated metric factor is in general a time-dependent solution of the generalized Liouville equation.     

Effect of Column Dimensions on HPLC Separations Using Constant Volume Columns

Abstract

The effect of column dimension on resolution, sample capacity, retention time, efficiency and mobile phase composition were studied, using both constant flow rate and constant linear velocity. The four columns selected (A = 238 × 3.2 mm, B = 153 × 4.0 mm, C = 116 × 4.6 mm and D = 50 × 7 mm) had the same volume. K¹ values were found to be constant, within experimental error, for all columns. At constant linear velocity, the retention time was found to be a linear function of column length, while at constant flow rate retention time was constant for all columns. The longest column (A) generated the largest N values while columns 3 and C gave the lowest H values, for dilute solutions, while they decreased with decreasing column length. On the other hand, it was observed that as the sample size increased, N generated by column A decreased more rapidly and eventually fell below the values generated by columns B and C. These two columns (B & C) can tolerate a larger sample size with less reduction in N value than the longest column. It is important to note that although there were minor differences in performance between columns B and C, there were significant differences between them (B and C) and the other two columns (A and D). Column A offered the highest sensitivity (narrower peaks) for dilute solutions, while columns B and C offered higher loadability. The volume of organic modifier in the mobile phase affected the retention equally in the four columns. It was also found that equal separation (a) was obtained for each column at constant flow rate and constant linear velocity, except with the latter the retention times were longer.     

Determination of ambroxol in an automated multi-pumping pulsed flow system.

A new flow methodology exploiting the multi-pumping approach was developed for the spectrophotometric determination of ambroxol hydrochloride in pharmaceutical preparations. The flow manifold was implemented by using, exclusively, multiple solenoid-actuated micro-pumps, which acted simultaneously as sample insertion, solutions propelling and reagents commutation units. Linear calibration plots were obtained over an ambroxol concentration ranging from 10 to 200 mg l(-1) (r.s.d. < 0.5%, n = 15) and a sampling rate of about 60 samples per hour (flow rate = 1.92 ml min(-1), sample volume = 80 microl).     

Two trends of sample dispersion variation with carrier flow rate in a single flow-injection manifold

Two trends of sample dispersion variation with carrier flow rate in a single flow-injection manifold are completely revealed for the first time and an inflection point in the dispersion coefficient (D) vs. flow rate (q) curve is discovered. With the increase of the flow rate, the value of D increases before the inflection point but decreases after the inflection point. The value of the carrier flow rate at the inflection point (q_m) is independent of the sample injection volume, the tube length, the tube coil radius and the tube inner diameter. It is only affected by the substance diffusion coefficient (D_m) of the analysis. The value of q_m decreases as D_m increases. Therefore, the value of D_m for a sample can be estimated according to the D_m vs. q_m curve.     

Piezoelectric pumping in flow analysis: Application to the spectrophotometric determination of gabapentin

Solutions propelling devices are fundamental components of a flow-based analytical manifold. In this work different manifold configurations were implemented to evaluate the performance of multiple piezoelectric micro-pumps used as solutions insertion and propulsion devices. The micro-pumps are piezo-actuated micro-diaphragm pumps with passive check valves characterised by a small compact size and low power demands, and are able to produce reproducible flow rates of up to 4 mL min⁻¹. The flow rate is controlled by the frequency of the piezoelectric actuator (up to 20 Hz). As an additional feature, piezoelectric micro-pumps actuation generates a pulsed flowing stream that ensures a faster sample/reagent mixing contributing to improved reaction development.

The developed flow approach was assessed in the spectrophotometric determination of gabapentin in pharmaceutical preparations upon reaction with 1,2-naphthoquinone-4-sulfonate in alkaline medium. Distinct flow manifold configurations were designed for achievement of different solutions management. Linear calibrations plots for gabapentin concentrations of up to 150 mg L⁻¹, with relative standard deviations of less than 1.50% (n = 10) and a sample throughput of about 28 determinations per hour, were obtained.     

Confluent streams in flow injection analysis

The addition of a confluent stream increases the mean length of the sample zone and simultaneously decreases the involved concentrations. Simple equations describing these effects under ideal mixing conditions are proposed. The effects of the confluent stream on the overall sample dispersion may be more or less compensated, depending on the decrease in the post-confluence dispersion. When this compensation is almost total, a paradoxical situation occurs, in which the recorded peak height becomes practically unaffected by variations in the flow rate of the merging stream. In this situation, the peak width approaches a limiting value which is independent of the injected volume and of the flow rate of the confluent stream. Limiting values for the peak width and for the mean length of the sample zone are postulated. When the post-confluence dispersion is negligible, the effects of the confluence appear in the recorded peak. The confluent stream addition reduces the overlap between successive sample zones. The site of the confluence may be an important dispersion factor. A saturation index is proposed and practical implications are discussed.     

Flow-injection extraction with a microvolume module based on integrated conduits

A self-contained module for liquid—liquid extractions is described. The module contains engraved conduits for mixing of sample and ragent, an engraved segmentor, a detachable extraction coil, a membrane separator, and a rinsing system for the flow cell. The membrane in the separator is supported by a teflon-coated steel grid and can be replaced rapidly. The segmented stream enters at the centre of the circular membrane and travels through an engraved, coiled channel in contact with the membrane before leaving the membrane area at the periphery. The volume of the receptor chamber for the organic phase is 10 μl. For a detector flow-cell volume of 8 μl, an aqueous flow rate of 2.0 ml min^?1 and an organic flow rate of 1.2 ml min^?1, the “loss factors” caused by analyte dispersion are 3.2 and 1.5 for caffeine sample volumes of 40 μl and 100 μl, respectively, compared with batch extraction. The system is also tested for extraction of anionic surfactants as their ion-pairs with methylene blue.