Pt–NiO/C anode electrocatalysts for direct methanol fuel cells

Pt catalyst was supported on Vulcan XC-72R containing 5 wt.% NiO using NaBH₄ as a reducing agent. The prepared catalyst was heat-treated at 400 °C. XRD, TEM and EDX analyses were applied to characterize Pt–NiO/C electrocatalyst. The introduction of NiO reduces the particle size of Pt crystallites. The electrocatalytic activity of Pt–NiO/C electrocatalysts was examined towards methanol oxidation reaction in 0.5 M H₂SO₄ solution using cyclic voltammetry and chronoamperometry techniques. A three fold increment in the oxidation current density was gained at Pt–NiO/C electrocatalyst compared to Pt/C one. The corresponding chronoamperograms showed high steady state current density values suggesting better stability of Pt–NiO/C electrocatalyst towards the carbonaceous poisoning species. The enhanced electrocatalytic performance and the long-term cycle durability of Pt–NiO/C electrocatalyst are attributed to the strong interaction between Pt and NiO and the formation of small Pt crystals.     

Determinants of anemia among pregnant women in Mali

BACKGROUND: Anemia in pregnancy remains a major problem in nearly all developing and many industrialized countries. In Mali, the subpopulation prevalence and etiology of anemia during pregnancy are largely unknown. OBJECTIVE: To examine the prevalence and likely etiologies of anemia in pregnancy in a poor urban population in Bamako, Mali. METHODS: Pregnant women (n = 190) were selected randomly. Hemoglobin, serum iron, and total iron-binding capacity were measured; blood smears were examined for Plasmodium falciparum malaria; and single stool and urine samples were examined for Schistosoma haematobium and hookworm. Gynecologic examinations were performed and interviews conducted to qualitatively assess food consumption and other socioeconomic characteristics. Associations among mild, moderate, and severe anemia; iron and parasite status; erythrocyte sedimentation rates; and the presence of abnormal vaginal discharge were evaluated. Differences in hemoglobin and serum iron concentrations, total iron-binding capacity, and anemia were compared according to trimester of pregnancy and between infected and noninfected women. The relative and attributable risks of anemia were calculated, and adjusted odds ratios for anemia and low serum iron were estimated by multivariate logistic regression. RESULTS: Of the 131 women for whom complete data were available, 47% had hemoglobin concentrations below 110 g/L; 13% had serum iron concentrations below 12 micromol/L; none had transferrin saturation values below 16%; 11%, 23%, and 8% harbored P. falciparum, S. haematobium, and hookworm, respectively; and 82% had an abnormal vaginal discharge. Food restrictions were reported by 45% of the women. Abnormal vaginal discharge correlated significantly with anemia (Pearson chi2 = 62.4; p < .01). Univariate and multivariate analyses found that infections were strongly associated with and predictive of anemia. CONCLUSIONS: Our data suggest that infections and food accessibility contribute to the high rates of anemia during pregnancy in Mali.     

Effect of Gamma-Rays on Corn Grains Part I. Influence on Starch Extraction and Quality of By-Products

In order to study the effect of irradiation of corn grains on the starch extraction and quality of by-products, the grains were subjected to different doses of gamma-rays. It was generally found that irradiation led to increase the water absorption during steeping. This increase in the water absorption increases the yield of starch and facilitates the removal of hulls and germ. However, at higher dose (1000 Krad) the yield of starch decreases. The results are discussed on the basis of effect of hydrogen bond protein denaturation, and formation of volatile compounds.     

The composition and activation aspects of El-Fayoum clays for using as a drilling fluid

The local consumption and the high importation cost of imported bentonite to Egypt led to find local substitute solutions for economical aspects. Hence, this paper presents the composition and activation capability of clays collected from the claystone quarries in Kom Oshim area at El-Fayoum province, Egypt for their application as a drilling fluid (water-based mud). It is an attempt to minimize the importation cost of the imported bentonites to Egypt by a local solution and maximize the usage of the studied clay sediments. The physical, chemical, thermal and mineralogical characteristics of five Egyptian clay samples were studied. The rheological properties of the prepared slurries from these samples and their activation characterization during studying the influence of NaOH and POLYPAC-R polymer as activators were investigated. It was found that the non-activated samples cannot be used as a drilling mud but it could be after the activation process where some significant changes in the rheological properties were observed. The experimental results revealed that the activated fitted samples may express as medium grade bentonitic clay and this type of clay can be used as a drilling fluid for shallow depth wells.     

Novel Terpolymers as Pour Point Depressants and Viscosity Modifiers for Lube Oil

Novel terpolymers were synthesized via free radical chain addition polymerization, using different molar ratios of the three used monomers (alkyl acrylate, styrene, and vinyl pyrrolidone). The structures of the prepared terpolymers were confirmed by FTIR, ¹H-NMR, and GPC. The prepared terpolymers were evaluated as pour point depressants and viscosity index improvers. It was found that terpolymers prepared from tetradecyl acrylate have a good efficiency than that prepared from hexadecyl acrylate as pour point depressants, and the viscosity index of lube oil increases with increasing the alkyl chain length of the alkyl acrylate used in the preparation of terpolymers.     

Stroboscopic studies of the elastic behaviour of some Indian timbers

The dynamic Young’s modulus has been determined for eleven Indian timbers using an electronic flash lamp stroboscope to measure the frequency of vibration of the timber bars. A linear relationship is observed between Young’s modulus and the density of the timbers.     

Impact of digital signal processing on measurement and testinstruments

The authors discuss the impact of digital signal processing on test instruments and describe the use of a single-chip digital signal processor called TriStar whose architecture has been tailored for the instrumentation environment. TriStar instructions and programming are described, and attention is given to typical applications of TriStar, including averaging, fast Fourier transform, and interpolations. The authors explain how the processor delivers high throughput for these applications     

Synthesis of some new azopyrazole dyes

A variety of new azopyrazolo [1,5-c]-as-triazine dyes have been synthesised via diazotisation of 3-amino-4-arylazo-1-pyrazolin-5-one and coupling with active hydrogen reagents. These dyed nylon 6, nylon 66, acrylic, polyester, silk and wool with colours ranging from scarlet red to dark brown and may find useful applications.     

Studies on the electrosynthesis of organic compounds II. Reducibility of some Schiff's bases on lead and copper cathodes

The electrochemical reducibility of some Schiff's bases was studied on copper and lead cathodes. The effects of different substituents and the nature of the cathode material on the reduction efficiency of these compounds were investigated. The products of reduction were found to catalyse the reduction process itself leading to an increase of reducibility (reduction efficiency) with time.     

Mass transfer at rotating finned cylinders

Rates of mass transfer at rotating finned cylinders were studied by an electrochemical technique involving the measurement of the limiting current for the cathodic reduction of potassiun ferricyanide in a large excess of sodium hydroxide. The variables studied were fin height and Reynolds number. The ratio of the fin height to the cylinder diameter (e/d) ranged from 0·0185 to 0·075 while the Reynolds number ranged from 1047 to 10 470. Under these conditions, the mass transfer data could be correlated by the equationJ=0·714(Re)^–0.39(e/d)^0.2 Nomenclature L _L limiting current (A) - K mass transfer coefficient (cm s^–1) - Z number of electrons involved in the reaction - C ferricyanide concentration (moles cm^–3) - F Faraday's constant - A projected cathode area (cm²) - u dynamic viscosity (g cm^–1 s^–1) - density (g cm^–3) - V peripheral velocity at the rotating cylinder (cm s^–1) - D diffusion coefficient of ferricyanide ion (cm²s^–1) - d cylinder diameter (cm) - e fin height (cm) - J (St)(Sc)^0.664 ColburnJ factor - (Sc) u/(D) Schmidt number - (Re) Vd/u Reynolds number - (St) K/V Stanton number