Computer-controlled ion-selective electrode switch

The construction of a microcomputer-controlled electrode switch for use in potentiometric determinations is described. This can be coupled to most of the analytical equipment usually found in laboratories, to enable a setting up of automatic systems capable of performing sequential determinations with several ion-selective electrodes. The assessment of its analytical usage and behaviour are discussed.     

Synthesis and characterization of binders

This paper presents an academic analysis of recent progress and changes in polymer science. These changes influence the coatings industry, as an answer to various constraints, such as enhanced applicability, quality certification, safety, and care of environment. We do not focus on a specific topic but instead consider the basic concepts, the chemical advances in polymer synthesis, and progress in fine characterization methods. Experimental results in polymerization, analysis, and new processes, obtained in recent years, in the final period of my laboratory activity, are illustrated. Presented at the 79th Annual Meeting of the Federation of Societies for Coatings Technology, in Atlanta, GA, Nov. 5–7, 2001. 200 Avenue Félix Faure, F-69003-Lyon, LMOPS, 69390 Vernaison on behalf of AFTPVA, France, email: arevillon@gonline.fr.     

Multihour engineering and traffic routing optimization in hierarchical telephone networks

Classical hierarchical routing in telephone networks is extended to a wider class called out-of-chain routing in such a way that some useful properties of hierarchical routing are retained. This new routing pattern offers more potential paths than the fixed hierarchical one and can be introduced as a dynamic routing where the fixed alternate sequences change at some predetermined instants during the day. The effect of this new routing pattern on the network performances is examined. The main topic of this paper is to present heuristic methods used to optimise such routings in large networks. We show on artificial networks that the throughput of a given network can be significantly improved by suitable routing choices. We demonstrate that the integration of routing changes within a multihour dimensioning process is possible but the lack of realistic data does not permit at this time to quantify the value of routing optimization on real networks.     

Determining the Tensile Stress-Crack Opening Curve of Concrete by Inverse Analysis

The determination of the fundamental stress versus crack opening (σ-w) response of concrete under uniaxial tension is performed in this study through inverse analysis using data from notched beam tests. The procedure used for optimizing the parameters of the σ-w relation using the load versus crack mouth opening displacement response of the notched beam is described. Satisfactory comparisons have been obtained between the σ-w curves obtained through the inverse analysis and those directly measured in uniaxial tension tests. The use of weighting functions in the inverse analysis may be necessary when large crack widths are to be considered.     

Electrodeposition of yellow bronze from acidic sulfate baths containing polyether laprol and micromolar additives of halides

The composition of yellow bronze coatings deposited from acidic sulfate solutions added with polyether laprol and the electrodeposition conditions are studied by voltammetry and XPS. It is found that halides in rather low (micromolar) concentrations affect significantly the partial electrodeposition processes. Chlorides increases cathodic polarization, widen the current window of the yellow bronze electrodeposition, and favor the increase in tin content of the coatings. Bromides narrow the current window, lower the tin content in the coatings, and hinder the yellow bronze surface oxidation. Iodides inhibit the copper electroreduction markedly, which makes the yellow bronze deposition practically impossible. Original Russian Text ? Z. Mockus, S. Kanapeckaité, V. Jasulaitiené, A. Survila, 2006, published in Zashchita Metallov, 2006, Vol. 42, No. 5, pp. 526–531.     

Chromosome comparison between populations of the collared peccary, Tayassu tajacu, raised in captivity

The collared peccary (Tayassu tajacu) is widely distributed over the American continent, being found from the south of the USA to the north of Argentina. In Brazil, it is spread all over the country, being one of the potential species to be raised in captivity. Therefore, the cytogenetic techniques could be a potential tool for reproductive monitoring of animals raised in captivity, mainly when destined for commercial purposes. This study had the objective of determining the chromosome number of two populations raised in captivity and characterizing them by GTG banding. For this purpose, an analysis was made of mitotic metaphases obtained from lymphocyte cultures made from blood samples of 11 animals, six of which from the Northeast and five from the North of Brazil. The results of this analysis showed the same karyotype pattern for the species (2n=30 chromosomes and NF=48), besides corresponding to the South American pattern of the species, i.e., without a translocation between autosomes 1 and 8, chromosome X acrocentric, and no differences were found between the two populations studied. However, chromosomal polymorphisms were observed compared to data from the literature on populations from North and South America.     

Sheet molding compound characterization using spiral flow

Sheet molding compound (SMC) is a fiber‐reinforced polymeric composite. It is often used in automotive, marine, and industrial applications over other materials because of its high strength to density ratio, resistance to corrosion, and low cost. There is a demand in the SMC industry to be able to characterize SMC processability. This is particularly true for heavy truck body panels, one of the fastest growing applications of SMC. Because of their large size and high strength requirement, the molding forces have a major influence in the molding cycle. Also because of the long flow paths involved, the ability of the paste to carry glass needs to be properly characterized when developing new SMC materials. In this article, we demonstrate the benefits of using spiral flow as a processability tester. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Inhibition et mémoire de travail : effet d'une privation aigu? de sommeil sur une tache de génération aléatoire.

The literature contains inconsistent data on the effects of acute sleep deprivation on the superior cognitive functions. The primary purpose of this study is to determine the effectiveness of inhibition, one of the functions of the working memory executive centre (EC), over an extended, 36-hour waking period. Inhibition is a cognitive mechanism whereby individuals ignore non-relevant information recorded in their working memory. We also tested the effects of a 36- hour period of acute sleep deprivation on simple reaction time. Twelve young, healthy volunteers (M=21.5 years, ?=2.3) performed a random generation task involving letters and a simple reaction time psychomotor test over four sessions held at 10-hour intervals. Each participant was assigned a "constant routine." Participants were kept awake in a prone position within a room whose environment was held strictly constant (light, noise, temperature, meals, etc.). This control procedure provided assurance that any variation in participant performance was solely caused by sleep deprivation. The random generation task, nearly two minutes in length, consisted in verbally producing a sequence of 100 letters in a random fashion (i.e. by inhibiting, for example, alphabetical order) and by keeping to a set rhythm... (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new amperometric biosensor for fructose determination based on epoxy-graphite-TTF-TCNQ-FDH-biocomposite

In this work a novel amperometric biosensor for fructose determination in solutions was developed. The device was constructed by the incorporation of a tetrathiofulvalene-tetracyanoquinodimethane organic conducting salt and fructose dehydrogenase enzyme, include in a polymeric matrix of epoxy resin and graphite powder. Because of the electrocatalytic function of the salt, the direct transfer of the electron between the reduced prosthetic group (PQQH₂) of the enzyme and the transducing material, was verified at a low working potential (150 mV vs. Ag/AgCl), where the interfering reactions were minimized. The response time at 90% of the steady state value was less than 20 s. The current response was directly proportional to the D-fructose concentration from 0.01 to 0.3 mmol/l with a detection limit of 0.005 mmol/l (signal/noise of 3) and a sensitivity of 1.9985 μA/mmol. The biosensor sensitivity diminishes when its surface is not polished between successive determinations, and remains constant (rsd=1.85, n=10) when the surface is polished between determinations. The effects of temperature and pH on the biosensor response were studied and analyzed; also the properties of the enzyme (Km _ap, I _max, Q₁₀) were determinate in this work. The biosensor was used to determine fructose in high fructose syrups and there were not significant differences between these results and those obtained by HPLC (p≤0.05). During 4 months, in intermittent determinations the biosensor kept 100% of its original sensitivity and after 18 months stored at 4°C, it only lost 32% of its sensitivity. The simplicity, low working potential, high stability and good performance of this biosensor shows a great potential for its use in the fructose determination.     

Investigation of the nucleation and growth mechanisms of nanocrystalline diamond/amorphous carbon nanocomposite films

Nucleation and growth, but especially the development of the morphology of nanocrystalline diamond/amorphous carbon (NCD/a-C) nanocomposite films have been investigated by systematic variation of three important parameters, namely the deposition time, the growth rate, and the substrate pre-treatment used to enhance the nucleation density. The films have been characterized, among others, by scanning electron microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. It is shown that, by successive addition of ultradispersive diamond powder to the suspension of nanocrystalline diamond powder in n-pentane used for the ultrasonic pre-treatment, the nucleation density can be enhanced by two orders of magnitude from 1 · 10⁸ cm^− 2 to > 1 · 10¹⁰ cm^− 2. This reduces the thickness required to achieve closed films from 1 µm to 100 nm. However, once coalescence of the individual nodules emerging from the nucleation sites has taken place the films loose “memory” of the nucleation step and start to develop the typical NCD morphology consisting of larger features with diameters of some hundreds of nm which are in turn composed of much smaller features. Irrespective of the feature size and of the parameters used, the films of this investigation possess AFM rms roughnesses of 9–13 nm, indicating that rms values are not sufficient to characterize NCD surfaces.