Corrosion study of nickel for alkaline water electrolysis

A study of the behaviour of nickel in the conditions of advanced electrolysis (130–180°C—40% KOH) shows the detrimental effect of oxygen in general corrosion. Corrosion can be limited by restricting sulfur content in nickel. No stress corrosion cracking is observed with nickel in KOH. Nickel appears to be more sensitive to cathodic hydrogen embrittlement than to gaseous hydrogen embrittlement.     

Friction coefficient and wear rate of sputter-deposited thin films and plasma-sprayed thick coatings at high temperatures in room air

Silver, calcium fluoride (CaF_x with x = 1.85) and chromium-carbon (Cr₃C₂) thin films were deposited onto various tribological test specimens by sputtering. The friction properties of sputter-deposited Ag and CaF_x single layers as well as Ag/CaF_x multilayer films were determined by ball-on-disk tribological tests conducted in room air under various experimental conditions. The tribological properties (friction coefficient and wear rate) of sputter-deposited CaF_x films were also determined at 500°C by pin-on-disk tribological tests performed with pin specimens made of cobalt-based alloy (alacrite). Chromium-carbon films sputter-deposited onto alacrite disk and counterfaces were found to be of interest for reducing the formation of alacrite wear debris in the wear tracks; thus reduced friction coefficient and wear rate values were obtained. The friction behavior of sputter-deposited CaF_x/Cr₃C₂ thin bilayer structures and plasma-sprayed (PS) chromium carbide/Ag/BaF₂-CaF₂ eutectic composite coatings (PS-212 type coatings) was investigated by plane-on-plane tribological tests conducted in room air at 500°C and 700°C. The friction performance of solid lubricant thin bilayer films was compared with that of thick PS-212 type coatings similar to coatings developed by NASA.     

Cooperative Metaheuristics for Exploring Proteomic Data

Most combinatorial optimization problems cannotbe solved exactly. A class of methods, calledmetaheuristics, has proved its efficiency togive good approximated solutions in areasonable time. Cooperative metaheuristics area sub-set of metaheuristics, which implies aparallel exploration of the search space byseveral entities with information exchangebetween them. The importance of informationexchange in the optimization process is relatedto the building block hypothesis ofevolutionary algorithms, which is based onthese two questions: what is the pertinentinformation of a given potential solution andhow this information can be shared? Aclassification of cooperative metaheuristicsmethods depending on the nature of cooperationinvolved is presented and the specificproperties of each class, as well as a way tocombine them, is discussed. Severalimprovements in the field of metaheuristics arealso given. In particular, a method to regulatethe use of classical genetic operators and todefine new more pertinent ones is proposed,taking advantage of a building block structuredrepresentation of the explored space. Ahierarchical approach resting on multiplelevels of cooperative metaheuristics is finallypresented, leading to the definition of acomplete concerted cooperation strategy. Someapplications of these concepts to difficultproteomics problems, including automaticprotein identification, biological motifinference and multiple sequence alignment arepresented. For each application, an innovativemethod based on the cooperation concept isgiven and compared with classical approaches.In the protein identification problem, a firstlevel of cooperation using swarm intelligenceis applied to the comparison of massspectrometric data with biological sequencedatabase, followed by a genetic programmingmethod to discover an optimal scoring function.The multiple sequence alignment problem isdecomposed in three steps involving severalevolutionary processes to infer different kindof biological motifs and a concertedcooperation strategy to build the sequencealignment according to their motif content.     

Analysis of the friction and wear behavior of hot work tool scale: application to the hot rolling process

In hot forming processes, the interface tool/product is important for the quality of the finished product. In hot rolling, the scale formed on the roll material plays an essential role. As soon as the contact oxide–oxide is established between the roll and the slab, friction allows the process to start. However, the oxide scale will continue to grow under the cyclic action of hot contacts and water cooling and will be subjected to thermo-mechanical stresses. Beyond a certain critical thickness, the oxidized surface layer of the cylinders has not sufficient mechanical strength to withstand the shear stresses.

The wear and friction behavior of the oxides appearing on the surface of the hot working rolls is not well known. The influence of these oxides on the friction and, consequently, the quality of the products of finishing mills, seems very significant. So, in this study, we investigate the evolution of the friction coefficient and the wear, according to the growth, the nature and the thickness of the formed scale. We use a high temperature pin on disc tribometer. The pin consists of material “rolls” while the disc consists of the slab. The pin is instrumented with thermocouples in order to couple the friction coefficient measurements with the thermal gradient in the pin and the surface temperature and the formed oxides. Then, the characterization of the surfaces is done by scanning electronic microscopy (SEM) and EDS analyses. We use the method of sin² Ψ to evaluate residual stresses of oxide and correlate these data with shear stress behavior.     

Contribution of the Chemical Structure of Wheat Starch to Japanese Noodle Quality

Wheat starch has been completely digested with bacterial α-amylase, and the pattern of oligosaccharides obtained from this digestion varies with starches from different wheat varieties. Wheat varieties of good Japanese noodle-making quality (based on sensory testing) give relatively small amounts of oligosaccharides with a degree of polymerisation (DP) of 5 or greater, while varieties of poor noodle-making quality give much greater amounts of these larger oligosaccharides. There is a significant negative correlation between the amount of DP5 oligosaccharide and noodle eating quality. The correlation between the amount of this oligosaccharide and starch paste viscosity was much smaller. The size of the HPLC peak corresponding to this oligosaccharide may be used as a rapid method of screening for noodle-making quality. Because oligosaccharides of greater than DP4 should have at least one branch point, the results suggest that the structure of the amylopectin in starch of good noodle-making wheats has relatively few branch points close together. Amylose also appeared to be important for noodle quality. The optimum amylose content seemed to be about 22% for good quality noodles, with starch of higher or lower amylose content coming from flour of lower noodle-making quality. Factors other than amylose content must contribute to noodle quality, as some flours of relatively poor noodle quality also contained close to the optimum amount of amylose. © 1997 SCI.     

Species abundance patterns in an ecosystem simulation studied through Fisher’s logseries

We have developed an individual-based evolving predator–prey ecosystem simulation that integrates, for the first time, a complex individual behaviour model, an evolutionary mechanism and a speciation process, at an acceptable computational cost. In this article, we analyse the species abundance patterns observed in the communities generated by our simulation, based on Fisher’s logseries. We propose a rigorous methodology for testing abundance data against the logseries. We show that our simulation produces coherent results, in terms of relative species abundance, when compared to classical ecological patterns. Some preliminary results are also provided about how our simulation is supporting ecological field results.     

Contribution of starch and non-starch parameters to the eating quality of japanese white salted noodles

Viscograph paste viscosity parameters of starches isolated from 42 wheat varieties were highly correlated with each other and with measures of the quality of the derived Japanese white salted noodles. Better correlations with noodle quality were obtained when measurements of wheat protein and grain hardness (PSI) as well as a starch viscosity parameter were included in the regression equations.     

Chemical vapour deposition of silicon onto iron: influence of silicon vapour phase source on the composition and nature of the coating

Armco iron was siliconized with two different gas mixtures in the temperature range of 750 to 1100 °C. The Ar-SiH₄-H₂ mixture leads mainly to the formation of a non-porous and adherent solid solution with a maximum silicon content of 6% by weight. For high concentrations of silane in the vapour phase or low treatment temperatures, non adherent pure silicon powder or flakey iron silicides may also depose. The use of Ar-SiH₄-SiCl₄-H₂ mixture leads to the immediate nucleation of Fe₃Si, the growth of which occurring from and around the open porosity of the coating. The influence of various parameters such as vapour phase composition and flow rate, hydrogen dilution and treatment temperature, is investigated and analysed in terms of limiting factors of the overall process: gas phase transport, interfacial reactions and diffusion velocity of different species in solid phase.     

Pacing in hypertrophic obstructive cardiomyopathy. A randomized crossover study. PIC Study Group

BACKGROUND: Uncontrolled studies have shown that short atrioventricular delay dual chamber pacing reduces outflow tract obstruction in hypertrophic obstructive cardiomyopathy. Although the exact mechanism of this beneficial effect is unclear, this seems a promising potential new treatment for hypertrophic obstructive cardiomyopathy. METHOD: In order to evaluate the impact of pacing therapy, were performed a randomized multicentre double-blind cross-over (pacemaker activated vs non activated) study to investigate modification of echocardiography, exercise tolerance, angina, dyspnoea and quality of life in 83 patients with a mean age of 53 (range 22-87) years with symptoms refractory or intolerant to classical drug treatment. RESULTS: After 12 weeks of activated or inactivated pacing, independent of which phase was first, the pressure gradient fell from 59 +/- 36 mmHg to 30 +/- 25 mmHg (P < 0.001) with active pacing. Exercise tolerance improved by 21% in those patients who at baseline tolerated less than 10 min of Bruce protocol; symptoms of dyspnoea and angina also improved significantly from NYHA class 2.4 to 1.4 and 1.0 to 0.4, respectively (P < 0.007). Quality of life assessment with a validated questionnaire objectivated the subjective improvement. CONCLUSION: Pacemaker therapy is of clinical and haemodynamic benefit for patients with hypertrophic obstructive cardiomyopathy, left ventricular outflow gradient at rest over 30 mmHg who are symptomatic despite drug treatment.     

Consequences of gamma-irradiation on inflammatory cytokine regulation in human monocytes/macrophages

We have investigated mitochondrial DNA (mtDNA) mutagenesis in the laboratory mouse. Using a nested PCR method for quantification, the absolute frequency, tissue distribution and rate of increase of mitochondrial deletion mutations was determined. Multiple deletions arise in brain, cardiac muscle and kidney tissues: deletions occur most frequently at regions of directly repeated mtDNA homology. Deletion frequencies rose by 2.5 x 10(5), 6300- and 4000-fold in heart, brain and kidney, respectively, between young and old mice. The rates of mtDNA mutation accumulation in mouse and human hearts are modeled well by exponential equations, with r-values of 0.96 and 0.97, and mutations rose much faster in mouse than human mtDNA per unit time. Thus, maintenance of the human mitochondrial genome is much better than that of mice, consistent with the higher rate and final extent of total DNA repair in humans than mice, that has been observed by others and consistent with the predictions of the disposable soma model of aging. A comparison of mtDNA mutagenesis from cardiocytes vs. whole heart tissue was undertaken. Deletion mutations were observed to be 100-fold lower in DNA prepared from isolated cardiocytes than from whole heart homogenates, consistent with a model of uneven mtDNA mutation accumulation.