Nucleation and growth of nickel by electrodeposition under galvanostatic conditions

The first stages of nickel electrodeposition on amorphous carbon and polycrystalline silver substrates have been studied under galvanostatic conditions. An island growth mode is observed on the two types of substrate. For equivalent conditions the cluster density is higher on silver substrates than on carbon substrates. Dissolution of some nickel clusters is observed a short time after the onset of electrolysis on carbon substrates. This is confirmed by the evolution of the current efficiency and the evolution of the metal surface cluster density as a function of the quantity of electricity.     

Cloning and characterization of the human and Caenorhabditis elegans homologs of the Saccharomyces cerevisiae MSH5 gene

Genetic variation among malaria parasites has important consequences with regard to drug resistance, pathogenicity, immunity, transmission, and speciation. In this regard, malaria parasites have been shown to display a high degree of inter- and intra-species genetic divergence. The nuclear genomes of Plasmodium falciparum, Plasmodium yoelii, and Plasmodium gallinaceum are vastly divergent yet share a similar codon usage and total A/T content of approximately 82%. This is in contrast to other primate-specific species including P. vivax which have an A/T content of approximately 67%. To assess the effects of this evolutionary divergence on the conservation of gene content, organization, and codon usage in the mitochondrial DNA (mtDNA) of malaria parasites, we have cloned and sequenced the mitochondrial genome of Plasmodium vivax, and compared it with the mtDNAs of P. falciparum, P. yoelii, and P. gallinaceum. The P. vivax mitochondrial genome was found to be 5990 base pairs in length, and displayed a gene organization identical to that of P. falciparum, P. yoelii, and P. gallinaceum. Furthermore, there was a remarkable 90% conservation of sequence identity between the mitochondrial genomes of all four species. As an example of intra-species conservation, comparison of mtDNAs from two independently cloned P. falciparum isolates, Malay Camp and C10, revealed only a single nucleotide substitution. A/T content of the P. vivax mitochondrial genome was found to be identical to other species of Plasmodium, hence, we have postulated that the mitochondrial genomes of malaria parasites were refractory to the evolutionary shifts in nucleotide content seen among the nuclear genomes of malaria parasites. Among different Plasmodium species, the second position of mitochondrial codons were found to be the least prone to substitutions and displayed a significant bias in pyrimidines. These aspects of mitochondrial codon usage were distinct from the nuclear genome and may reflect functional aspects of decoding by the mitochondrial translational system.     

Advanced product planning: a comprehensive process for systemic definition of new product requirements

This paper reports results of research into the definition of requirements for new consumer products––specifically, electro-mechanical products. The research dealt with the derivation of design requirements that are demonstrably aligned with stakeholder needs. The paper describes a comprehensive process that can enable product development teams to deal with statements of product requirements, as originally collected through market research activities, in a systematic and traceable manner from the early, fuzzy front end, stages of the design process. The process described has been based on principles of systems engineering. A case study from its application and evaluation drawn from the power sector is described in this paper. The case study demonstrates how the process can significantly improve product quality planning practices through revision of captured product requirements, analysis of stakeholder requirements and derivation of design requirements. The paper discusses benefits and issues from the use of the process by product development teams, and identifies areas for further research. Finally, the conclusions drawn from the reported research are presented.

Effects of heat treatments on the ductility of cobalt electrodeposits

The effects of annealing treatments on the structure and mechanical properties of cobalt electrodeposits have been studied. Annealing temperatures range from 250–800 °C, i.e. below, as well as above, the allotropic -h c p -f c c transformation temperature (417 °C). The structural characterization included hydrogen content measurement, relative volume fraction of and phases determination by X-ray diffraction, and microstructural investigations by optical and electron microscopy. The results showed that an annealing is a very effective means to optimize the ductility of cobalt electrodeposits. The increase of ductility observed after annealing is essentially due to a decrease of the stacking fault density in the deposits. Annealing treatment above the allotropic transformation temperature also produces, in some deposits, an increase of the ductile -f c c phase content, but this fact does not lead to supplementary improvements of ductility. This is due to the detrimental influence of hydrogen that always exists in these deposits.     

Electropolymerization of poly(2-vinylpyridine) films on zinc

The electroreductive polymerization on a zinc substrate of 2-vinylpyridine in aqueous solution produces thin films. Various electropolymerization conditions have been studied. The deposits have been characterized structurally and compositionally. The best films were obtained at 50°C by potentiostatic polymerization at –1.26 V vs NHE for 15 min.     

A modified Hull cell with forced electrolyte flow: simulation of industrial electroplating conditions

Hull cells are often used to determine the optimum current density range for industrial electroplating. However, these cells do not reproduce correctly the hydrodynamic conditions. The design and the use of a modified Hull cell able to reproduce constant hydrodynamic conditions at the cathode for a large range of circulation speeds are described. Mass transfer and current distribution at the cathode have been evaluated in this cell for copper and zinc deposition.     

Structural and dimensional stabilities of tin-bismuth fusible cores

Eutectic tin-bismuth alloys, used as fusible cores for high polymer injection moulding, were studied in order to identify structural and dimensional modifications during ageing at temperatures ranging from 4 to 110°C. Optical and scanning electron microscopies together with X-ray diffraction were used to observe the coarsening of the eutectic structure and to plot an isothermal transformation diagram. Thermal cycles around the eutectic temperature promoted the dissociation of the eutectic structure into light tin dendrites at the top of the ingots and heavy bismuth crystals at the bottom. Differential scanning calorimetry and thermomechanical analysis were performed to observe possible phase transformations.     

Effect of flow characteristics on the diffusion-limited current density in an electrodeposition cell

The main parameters characterizing the effect of the turbulent flow of an electrolyte between two planar electrodes, one of which may be in motion, are demonstrated by means of numerical and experimental studies. The analysis is carried out for the case of zinc electrodeposition. A model is proposed, which takes into account the production of hydrogen, to represent the variation of the diffusion limited current density as a function of the flow characteristics and of the solution composition.     

Ionic conductivity of the Na1+xM x III Zr2−x(PO4)3 systems (M = Al,Ga, Cr,Fe, Sc,In, Y,Yb)

The existence and ionic conductivity of solid solutions Na_1+xM _x ^III Zr_2–x(PO₄)₃ with Nasicon-like structure have been investigated and the results compared with literature data. A limited range of solid solutions is formed with M^III = aluminium, gallium, yttrium, ytterbium, whereas a continuous series is obtained for M^III = chromium, iron, scandium, indium. The pure end member Na₃ln₂(PO₄)₃ is reported for the first time; according to powder diffraction data, it is hexagonal witha = 0.8966(1) andc = 2.2104(4) nm. The small monoclinic distortion already known for M^III = chromium, iron and scandium is restricted tox values very close to 2. Ionic conductivity measurements show that for a given value ofx, the mobility of the Na⁺ ions is strongly influenced both by the ionic radius and the type of electronic structure of the M^III ion. However, no simple correlation can be found.