离子选择电极用于沉淀反应电位滴定的等当点和溶度积的测定

沉淀反应电位滴定的等当点,在经典的电位滴定法中总是由电位和溶液体积作图,从曲线的拐点、或一级微商、二级微商法来确定。本文从沉淀反应体系中离子浓度的平衡关系,研究了沉淀滴定过程中各种变量之间的相互关系的数学表示式。并用电子计算机程序计算法求得了等当点体积(V_e)和溶度积常数(K_sp)。应用离子选择电极测定滴定体     

苦味酸根电极指示电位滴定某些生物碱

Hadjiioannou等基于某些生物碱与苦味酸形成离子对缔合物沉淀,以苦味酸根离子电极指示,电位滴定马钱子碱、罂粟碱、奎宁与可卡因。本法以类似方法测定马钱子碱,二甲马钱子碱与黄连素,亦得到良好的结果。对于硝酸马钱子碱的电位滴定,其pH范围为2—7,最佳酸度为pH=6。当pH>10时,发生沉淀,不能进行滴定。对于二甲马钱子碱的电位滴定,其pH范围为1—8,通常pH5—6较为适宜,当pH>9时,发生沉淀。     

沉淀滴定和离子对形成滴定

电位滴定是最准确的分析方法之一,对中常量物质的测定,准确度可到0.1%以上,目前沉淀滴定和离子对形成滴定随离子选择电极的发展有很大的发展,本文对这类滴定应用的概况,滴定终点的确定,滴定的误差及溶度积的测定等方面,结合作者工作中的体会作一些介绍。     

用铅离子选择电极电位滴定钼

钼的容量分析法有络合滴定法,氧化还原滴定法和沉淀滴定法。由于缺乏适宜的指示剂,目前主要采用回滴定的方法测定钼。文献曾用铅离子选择电极电位滴定钼酸盐、钨酸盐、高铼酸盐和氟化物,但未见用于矿样分析。我们在上述资料的基础上,实验确定了电位滴定钼(Ⅵ)的最佳底液条件,试验了共存离子的影响,在此基础上拟定了电位滴定测定钼精矿和钼焙砂中高含量钼的方法,方     

用氟硼酸根电极电位滴定法间接测定磷酸二氢钠中的硫酸根

R.J.Levins和R.M.Ikeda在1965年提出了用四苯硼化钠直接电位滴定聚乙二醇及其衍生物;随后在1971年R.J.Levins同样利用聚乙二醇、钡和四苯硼化钠生成的(钅羊)盐沉淀这一性质,试制成了钡离子选择电极;殷学锋等成功地应用四苯硼酸根电极以四苯硼化钠滴定钡离子和镀铬液中的硫酸根。我们以氟硼酸根电极为指示电极,在聚乙二醇(PEG—600)存在下,加入过量的钡标准溶液沉淀硫酸根,然后用四苯硼化钠     

直线法测定沉淀滴定的终点

直线法作沉淀滴定的终点定位,具有快速、分析范围较大(浓度较低亦可应用)、适合于自动分析等优点。该法等量分步加入滴定剂,并采用离子选择电极测定电极电位,用计算器完成计算。     

离子选择电极应用于沉淀反应溶度积的测定——苯札溴胺—TPB和服止宁—TPB等缔合物的Ksp

离子选择电极电位法测定沉淀的溶度积的方法多为测出离子活度按活度乘积直接进行计算。作者在前文中介绍了利用滴定曲线方程式和最小二乘计算处理求得溶度积和等当点的方法。本文用自制的苯扎溴胺药物电极和服止宁药物电极,测定了它们与四苯硼钠形成缔合物沉淀的K_(sp),还用铜、铝离子电极测定了邻氨基苯甲酸和铜铁试剂与Cu~(2+),pb~(2+)离子生成沉淀的K_(sp)。用回归程序进行数据处理得到了满意的结果。     

电位法测定钨酸铅的溶度积常数

钨酸铅的溶度积常数已有报道,但文献[1]报道的数值(4.5×10~(-7))与文献[2]报道的数值(8.4×10~(-11))相差达三个半数量级。对此进行校检,甚感必要。E.E.Chao曾用银离子选择电极,采用混合溶液电位分步滴定的方法,测定、校验过若干难溶银盐的溶度积常数。我们试用铅离子选择电极作指示电极,用分别滴定的方法,进行钨酸铅溶度积常数的测定,其测定结果为(4.3±0.3)×10~(-11)。由于采用了分别滴定的方法,从而避免了混合溶液分步滴定时形成的沉淀对电极表面性能的影响。     

用银离子选择性电极测定含氮有机物质

四苯硼离子除与无机离子如K~ 、NH_4~ 、Tl~ 、Ag~ 等生成白色难溶盐外,也能和某些含氮有机物如胺、生物碱和含氮碱性药物生成白色沉淀。利用该特性,我们提出某些含氨有机物的间接Gran滴定测定法,即加入过量的四苯硼钠标液与含氮有机物作用:     

铅电极在药物分析中的应用

引言离子选择电极是新型电化学测试器件在药物的有效成份分析,成品药质量控制、药理研究等方面也开展了广泛的应用1979年S.S.Hassan利用K_2P_bO_2与维生素B_1作用生成P_bS沉淀,以P_b~(2+)-ISE为指示电极。EDTA溶液为滴定剂进行电位滴定,间接求得维生素B_1的含量。1982年Selig Walter利用P_b~(2+)—ISE测定了丹参注射液中某些取代儿茶酚。     

A method of defuzzification based on the approach of areas' ratio

The new method of defuzzification of output parameters from the base of fuzzy rules for a Mamdani fuzzy controller is given in the paper. The peculiarity of the method is the usage of the universal equation for the area computation of the geometric shapes. During the realization of fuzzy inference linguistic terms, the structure changes from the triangular into a trapezoidal shape. That is why the universal equation is used. The method is limited and can be used only for the triangular and trapezoidal membership functions. Gaussian functions can also be used while modifying the proposed method. Traditional defuzzification models such as Middle of Maxima − MoM, First of Maxima − FoM, Last of Maxima − LoM, First of Suppport − FoS, Last of Support − LoS, Middle of Support − MoS, Center of Sums − CoS, Model of Height − MoH have a number of systematic errors: curse of dimensionality, partition of unity condition and absence of additivity. The above-mentioned methods can be seen as Center of Gravity − CoG, which has the same errors. These errors lead to the fact that accuracy of fuzzy systems decreases, because during the training root mean square error increases. One of the reasons that provokes the errors is that some of the activated fuzzy rules are excluded from the fuzzy inference. It is also possible to increase the accuracy of the fuzzy system through properties of continuity. The proposed method guarantees fulfilling of the property of continuity, as the intersection point of the adjustment linguistic terms equals 0.5 when a parametrized membership function is used. The causes of errors and a way to delete them are reviewed in the paper. The proposed method excludes errors which are inherent to the traditional and non- traditional models of defuzzification. Comparative analysis of the proposed method of defuzzification with traditional and non-traditional models shows its effectiveness.     

Schematic classification problems and their solution

The necessity arises in a variety of tasks to classify items on the basis of the presence of one of a number of criterial sets of co-related feature values. Such sets are called class characteristics. Because such classification problems require the identification of characteristics on the basis of limited training information, they entail a difficult search problem. Consideration of the differences between the theoretical models underlying characteristic and volume pattern generators suggests a schematic approach. Schemata, sets of commonly co-occuring features values, are probabilistic indicators of class membership whenever the characteristics are unknown but the characteristic model prevails. Formal and algorithmic solutions to the classification problem when exemplars are simple (consist only of M feature or attribute values) are described. The relevance of these procedures to problems involving general (relational) data structures is also indicated.     

Ethical and legal issues for writing researchers in an age of media convergence

With the convergence of digital media into ever-widening social and technological networks for creation and distribution, the contexts for writing and the study of writing and writers have certainly changed. Researchers must navigate a dense matrix of ethical and legal issues in all phases of research when studying the ever-changing processes and products of digital communications. In this article, I draw from numerous sources to articulate a few of the challenges facing digital writing researchers in this age of convergence, focusing on issues of representation (researcher, participant, third-party), issues of informed consent, and issues of copyright and fair use.     

Interface as Exordium: The Rhetoric of Interactivity

In this article, I outline how the interface of new media functions rhetorically as an exordium to engage users and to dispose them to persuasion. The modular, networked, and interactive nature of new media requires an interface: a central place of interaction for the technological, human, social, and cultural aspects of new media. I propose that the interface functions rhetorically through three modes of interactivity, including multi-directionality, manipulability, and presence. By understanding these modes of interactivity and how they function to create various degrees of interaction and engagement, we can begin to develop the analytic tools needed to increase critical awareness of the interface. A rhetorical understanding of the interface enables us and our students to see that the shape and design of the interface is not natural and inevitable. The design of the interface is a design of human experience and, as such, the interface becomes a locus of power. The modes of interactivity it deploys are capable of enabling empowerment and enacting rhetorical patterns of control.     

基于XML的中间层交互技术的研究

由于HTML自身的不足．所以无法适应Web发展的复杂性和多变性，也不利于机器之间的数据交换和信息传递，通过对XML和HTML作多个角度的对比，文中提出将XML作为载体实现Web上的动态交互。首先从XML的自身特点出发，分析了XML驱动下的Web体系结构，从而得出基于XML的中间层交互技术的实现原理．重点研究了如何设计与XML相匹配的Web数据库，用XML查询数据库的实现方法，以及如何构造从XML到数据库的映射关系，具体包括从XIviL的DTD或者Schema出发来设计数据库的结构或者从数据库本身出发来构造与之相适应的DTD或Schema，最后分析了浏览XML格式信息的诸多策略。     

New debates on learning support

Abstract In the present debate on knowledge management and multimedia support of human learning, the word 'mediation' (of conduct) is often used as a natural correlate and rough equivalent to the word 'mediatisation' (of information). It is suggested that the distinction between the two words points to a basic difference between two types of processes which are crucial to a much needed rethinking of the conception and design of humanmachine interaction (HCI).
A redefinition of the 'appropriateness' of media support as the quality of the help to people's self-help rather than of direct control of their behaviour is proposed. Such a redefinition implies a radical shift of paradigm allowing for approaches to human learning as a cognitive activity in its own right. Another view of technological mediation is advocated, in keeping with some recent developments in HCI.     

基于WWW技术的水政水资源管理系统的设计与实现

该文结合连云港水政水资源综合信息系统的开发过程,分析了基于B/S结构的信息系统的基本特征及运行机制,具体介绍了一种基于WWW技术的系统设计方案,并对其中的一些关键技术进行了研究。     

HUYGENS' PRINCIPLE,PHYSICS AND COMPUTERS

We discuss the emergence of topology from a consideration of set extensions in General Systems Theory. Boundaries arise in a natural way, separating independent elements or regions of the system. Our aim is a unification of Etter theory, Kron's method of Tearing and Jessel's formulation of Huygens' Principle. This should make explicit the equivalence between the objective, structural, holographic and the subjective, relative definitions of information, sought in Bowden (1994b), reprinted in this Special Issue. It connects the abstract generalisations of Schrodinger's equation and Bom's rule derived in probabilistic Etter theory with the real world of electrical and other physical phenomena in General Physical Systems Theory. This paper can be considered as a continuation of Bowden (1990; 1994a) and as a response to Bowden (1994b), reprinted in this issue.

We review the ideas behind Kron's Method of Tearing and Jessel's Principle of Secondary sources (both special cases of the above theory) and their equivalence. We follow Hiley's argument in Hiley (1996) to show how Schrodinger's equation can be thought of as specifying the evolution of (a series of) tearings in continuous space. These can be shown on a commutative diagram as a series of similarity transforms. We compare this with Etter's derivation (Etter, 1998). We describe briefly a recently published derivation of Maxwell's equations from a non-commutative algebra and show how they fit onto a related commutative diagram. Finally we make some comments on applications of the general theory to computer systems. This paper is a series of vignettes of work in progress. It is designed to point the direction of work to come in Constructive Physics.     

An approach to the synthesis of fuzzy stabilization systems with a priori unknown model of an object

A method of synthesis of fuzzy stabilization systems for a broad class of dynamic objects under the assumption that the mathematical model of the object is not known a priori is proposed. The control is formulated in the form of a proportional law of adjustment as a function of a macro-variable; the square of the Euclidean norm of the phase variables is adopted as the macro-variable. An analogous variable characterizes the distance of the object from the equilibrium position. Despite the simplicity of the control law, its sign remains constant due to the fact that the macro-variable is positive-definite over the entire phase space. The switching times of the signals are determined by fuzzy identification of the system’s dynamic modes on the basis of measurement of the derivatives of the macro-variable.     

因素空间与可拓学的互补性分析及问题处理融合模型

问题智能处理是人工智能领域具有挑战性和交叉性的课题。大数据与人工智能技术背景下,为了给具有较高普遍性的开放性问题求解提供新的理论支撑,对因素空间与可拓学做了对比分析,发现两者具有共同的数学基础,在问题智能处理等研究方向有交叉性和互补性。以面向问题处理的融合模型为例,论证了可拓学与因素空间交叉研究的基本路径及其可行性,提出了两者交叉研究的主要方向,阐明了实际应用的潜在优势及适用范围。该研究将有助于进一步提高问题处理的系统性、智能化水平,提高解决问题从不确定性、偶然性到必然性的程度,并将推动为智能科学服务的智能数学的发展。