Alkaline earth metal oxides on γ-Al2O3 supported Co catalyst and their application to mercaptan oxidation

γ-Al₂O₃-supported alkaline earth metal oxide samples with different MgO, CaO, SrO and BaO loadings have been prepared by impregnating γ-Al₂O₃ with alkaline earth metal nitrate solutions and then calcining at 773 K and 1,023 K. The resultant samples have been characterized by XRD, EDS coupled with SEM, CO₂-TPD and BET. After preparation of the γ-Al₂O₃-supported alkaline earth metal oxide samples and impregnation with the liquid catalyst LCPs30, supplied by Axens, the catalytic performance of these catalysts was evaluated in the mercaptan oxidation reaction. Results showed that magnesium base oxide is formed at 773 K and base oxides of calcium, barium and strontium are formed at 1,023 K. Catalysts with higher mole ratios have higher conversions and the basicity increases with increasing base oxide loading in the samples. Furthermore, the conversion of mercaptans increases with increasing atomic number of the alkaline earth metal, excluding MgO, which has the highest conversion compared to the other base oxides.     

Sonochemical synthesis of Pt-doped Pd nanoparticles with enhanced electrocatalytic activity for formic acid oxidation reaction

Pt-doped Pd nanoparticle catalysts (Pd _n Pt, n is 12, 15 and 19) supported on carbon were synthesized by an ultrasound assisted polyol method. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy. The electrochemical activity of the electrocatalysts was investigated in terms of formic acid oxidation reaction (FAOR) at low concentration of formic acid in 0.1 M perchloric acid at room temperature. Formic acid oxidation on the Pd _n Pt/C commences at lower potential than a commercial Pt/C. Pd₁₉Pt/C catalyst showed the highest catalytic activity in FAOR compared to that of other catalysts. The obtained electrochemical results from voltammograms indicate that Pt-doped Pd catalysts can be a promising candidate for the anode material in direct formic acid fuel cells. The synthesis procedure is not only a very facile route but also a mass producible method for preparing carbon supported alloy nanoparticles.     

Boehmite nanopetals self assembled to form rosette-like nanostructures

Rosette-like boehmite nanostructures were prepared successfully via a simple hydrothermal process. The obtained material was characterized with X-ray powder diffractometry (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Using Scherrer formula, the average crystallite size of the obtained boehmite rosettes was measured to be about 8 nm. It was shown that boehmite nanopetals with average width of about 41 nm determined by TEM, were formed during the hydrothermal process and then self assembled due to weak hydrogen bonds to fabricate boehmite rosettes. The specific surface area of the obtained rosette-like nanostructures was calculated through BET N₂-adsorption technique to be about 143.08 m²/g.     

Gender, agricultural commercialization, and collective action in Kenya

With the commercialization of agriculture, women are increasingly disadvantaged because of persistent gender disparities in access to productive resources. Farmer collective action that intends to improve smallholder access to markets and technology could potentially accelerate this trend. Here, we use survey data of small-scale banana producers in Kenya to investigate the gender implications of recently established farmer groups. Traditionally, banana has been a women??s crop in Kenya. Our results confirm that the groups contribute to increasing male control over banana. We also analyze nutritional implications. While male control over banana revenues does not affect household calorie consumption, it has a negative marginal effect on dietary quality. We demonstrate that the negative gender implications of farmer groups can be avoided when women are group members themselves. In the poorest income segments, group membership even seems to have a positive effect on female-controlled income share. Some policy implications towards gender mainstreaming of farmer collective action are discussed.     

Performance of a household-level arsenic removal system during 4-month deployments in Bangladesh

A simple arsenic removal system was used in Bangladesh by six households for 4 months to treat well water containing 190-750 microg/L As as well as 0.4-20 mg/L Fe and 0.2-1.9 mg/L P. The system removes As from a 16-L batch of water in a bucket by filtration through a sand bed following the addition of about 1.5 g of ferric sulfate and 0.5 g of calcium hypochlorite. Arsenic concentrations in all but 1 of 72 samples of treated water were below the Bangladesh drinking water standard of 50 microg/L for As. Approximately half of the samples also met the World Health Organization (WHO) guideline of 10 microg/L. At the two wells that did not meet the WHO guideline, observations were confirmed by additional experiments in one case ([P] = 1.9 mg/L) but not in the other, suggesting that the latter household was probably not following the instructions. Observed residual As levels are consistent with predictions from a surface complexation model only if the site density is increased to 2 mol/mol of Fe. With the exception of Mn, the average concentrations of other inorganic constituents of health concern (Cr, Ni, Cu, Se, Mo, Cd, Sb, Ba, Hg, Pb, and U) in treated water were below their respective WHO guideline for drinking water.     

The nutrition transition and indicators of child malnutrition

This study examines how the nutrition transition, which involves a westernization of diets and increased consumption of calorie-dense, processed foods, affects child malnutrition in developing countries. It is often assumed that the nutrition transition affects child weight but not child growth, which could be one reason why child underweight decreases faster than child stunting. But these effects have hardly been analyzed empirically. Cross-country panel regressions show that the nutrition transition reduces child underweight, while no consistent effect on child overweight is found. Against common views, our results also suggest that the nutrition transition reduces child stunting. Further research is required to confirm these findings.     

Fischer–Tropsch Synthesis on Co/Al2O3 Catalyst: Effect of Pretreatment Procedure

The effect of pretreatment procedure on catalytic performance during Fischer–Tropsch synthesis (FTS) of unpromoted cobalt on alumina (15 %Co/Al₂O₃) catalyst was studied in a fixed-bed reactor. Pure carbon monoxide or a mixture of hydrogen and carbon monoxide were used as reducing agents prior to FTS. Pretreatments with pure CO result in low activity and high selectivity to methane and gaseous hydrocarbons in comparison to standard hydrogen reduction. The use of synthesis gas (H₂/CO = 2/1) as a reducing agent resulted in high initial activity and high selectivity to gaseous hydrocarbons. Pretreatment procedure that utilized synthesis gas after the CO reduction resulted in low activity but high selectivity to high molecular weight hydrocarbons. Catalyst performance is strongly affected by the presence of cobalt carbides, cobalt oxide and/or various types of carbon species on the surface as determined by X-ray diffraction and temperature-programmed hydrogenation and oxidation characterization techniques.