M. Dominguez

Derivation and experimental verification of approximate explicit equations in differential pulse polarography Part II. Second-order processes

Abstract An approximate method applicable to electrochemical processes either coupled or not to first order chemical reactions in differential pulse polarography is proposed. A program has been prepared in order to enable the authors to interpret DP polarograms. The method has been tested with the aid of well-known oxidation and reduction processes. The utility of the method is shown, particularly in those cases involving overlapping DP polarographic waves. Applications to determinations of kinetic parameters and quantitative analysis have also been made.

Diagnostic criteria for characterization of CE and CEC mechanisms in polarography

Abstract From a calculation based on the reaction layer theory, several expressions have been developed to differentiate EC and CEC mechanisms when the transfer is reversible. In order to check these equations, they have been applied to the pyridine-4-aldehyde reduction and close agreement between the experimental and theoretical results was obtained for a CEC mechanism, with the last stage being a dimerization reaction.

Resolution of absorption spectra

Abstract Absorption spectra are resolved on the basis of lognormal distribution. A procedure is described for resolving absorption spectra in terms of skewed bands.

Derivation and experimental verification of approximate explicit equations in differential pulse polarography: Part III. Diagnostic criteria for characterization of first-order processes

Abstract From an approximate equation previously derived, several diagnostic criteria have been developed to differentiate electrochemical processes coupled or not to first-order reactions. To check these criteria, they have been applied to the reductions of Cd(II) ion, diacetyl and alloxan, and a close agreement between experimental and theoretical results was obtained in all cases. Moreover, the range of applicability of these equations is also discussed and tested.

A curve-fitting program set for handling of differential pulse polarograms

Abstract DP polarograms corresponding to both first- and second-order processes are treated on the basis of approximate equations. Overlapped peaks can also be analysed. BASIC curve-fitting programs running on a APPLE II+ are proposed and tested. Applications to electrochemical kinetics and routine analyses are also considered.

Analysis of source code metrics from ns-2 and ns-3 network simulators

Abstract Ns-2 and its successor ns-3 are discrete-event simulators which are closely related to each other as they share common background, concepts and similar aims. Ns-3 is still under development, but it offers some interesting characteristics for developers while ns-2 still has a large user base. While other studies have compared different network simulators, focusing on performance measurements, in this paper we adopted a different approach by focusing on technical characteristics and using software metrics to obtain useful conclusions. We chose ns-2 and ns-3 for our case study because of the popularity of the former in research and the increasing use of the latter. This reflects the current situation where ns-3 has emerged as a viable alternative to ns-2 due to its features and design. The paper assesses the current state of both projects and their respective evolution supported by the measurements obtained from a broad set of software metrics. By considering other qualitative characteristics we obtained a summary of technical features of both simulators including, architectural design, software dependencies or documentation policies.

Architecture, design and source code comparison of ns-2 and ns-3 network simulators

Ns-2 and its successor ns-3 are discrete-event simulators. Ns-3 is still under development, but offers some interesting characteristics for developers while ns-2 still has a big user base. This paper remarks current differences between both tools from developers point of view. Leaving performance and resources consumption aside, technical issues described in the present paper might help to choose one or another alternative depending of simulation and project management requirements.

Electro-oxidation mechanism of D-araboascorbic acid on a mercury drop electrode. I

Abstract A study was carried out on the oxidation mechanism over DME of D-araboascorbic acid and two distinct bielectronic processes were discovered. The first take place through a post-kinetic mechanism and the second through a pre-kinetic mechanism. The global reaction of the first process was determined together with the kinetic parameters at the foot of the wave. A basic plan was drawn up showing experimental and theoretical data.

Programmable microcomputer-controlled ramp generator for use in electrochemical experiments

Abstract In this article a microcomputer-controlled circuit for generation of linear analog waveforms for use in electrochemical experiments is proposed. The circuit permits the generation of complex waveforms, uses an inexpensive 8-bit D/A converter, and is adaptable to microcomputers with parallel I/O interface.

Electrochemical behaviour of pyridoxal-5′-phosphate Schiff base with n-hexylamine

Abstract A study of the reduction of pyridoxal-5′-phosphate Schiff base with n -hexylamine at a d.m.e. in a wide pH range was carried out. The effects of pH and amine and ethanol concentrations on the d.c. and d.p.p. were studied. The equilibrium formation constant of the Schiff base in aqueous solutions for the entire pH range was calculated. The results found show no direct influence of the ionization equilibria of the Schiff base on the reduction potential of the different species present in the aqueous solution. The effect of ethanol concentration on the formation constant are discussed. Evidence of the influence of protonation equilibria in ethanol-water solutions was obtained by d.p.p.