Radioactive method enables determination of surface areas rapidly and accurately

Radioactive krypton adsorption technique is used to determine the surface area of more than one sample of material simultaneously

Microwave-assisted hydrothermal synthesis of carbon monolith via a soft-template method using resorcinol and formaldehyde as carbon precursor and pluronic F127 as template

A new microwave-assisted hydrothermal synthesis of carbon monolith is reported in this work. The process uses microwave heating at 100 °C under acidic condition by employing a triblock copolymer F127 as the template, and resorcinol–formaldehyde as the carbon precursor. Scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen sorption measurements, transmission electron microscopy, X-ray studies and thermogravimetic analysis were used to characterize the synthesized material. The carbon monolith is crack-free, mesoporous and has a high surface area of 697 m²/g. The results demonstrate that the microwave-assisted hydrothermal synthesis is a fast and simple approach to obtain carbon monoliths, as it reduces effectively the synthesis time from hours to a few minutes which could be an advantage in the large scale production of the material

Toxicity Evaluation of the Liver and in vitro Metabolism in Wistar Rat on Exposure to N-Nitrosamine Precursors

The aim of this study is to evaluate liver toxicity on exposure to n-nitrosamine precursors as well as the effect of ultraviolet light on n-nitrosamines and its precursors. Toxicological evaluation of the liver following single dose treatment of wistar rat with 8.2125 mg NaNO2/adult rat and in rats given a combined dose of 50 mgDMA-HCl and 8.2125 mg NaNO2/adult rat showed a steady elevation of the liver function enzymes. Histopathological analysis of the liver showed hepatic necrosis in the chemical induced rats. Following UV exposure after in vitro incubation of rat liver microsomal plus soluble fraction with NaNO2 and NaNO2 plus DMA-HCl, nitrite concentration in the NaNO2 incubation medium was 19.5 and 2.2 μg/mL before and after UV exposure respectively while the nitrite concentration in the NaNO2 plus DMA-HCl incubation medium was 23.5 and 2.5 μg/mL, respectively. Nitrite loss was significant (p<0.05) between before and after UV exposure in all groups. UV exposure, thus degraded the nitrosamine precursors, nitrite and DMA-HCl, thereby inhibiting possible nitrosation. The high values of the activities of serum transaminases (AST and ALT), alkaline phosphatases (ALP) and gammaglutamyltransferses (γ-GT), relative to control values are indicative of severe intrahepatic cell damag

Microstructural Characterization and Some Mechanical Behaviour of Low Manganese Austempered Ferritic Ductile Iron

This work studied the microstructural characterization and mechanical behavior of low manganese Austempered Ductile Iron (ADI), with a view to improve the properties of iron and to increase the areas of applications. Three sets of ductile iron of specified composition were machined from Y-blocks to tensile and hardness pieces. The samples were preheated at 350 0C for 1hr and austenitised at 900 0C for 1hr in salt bath furnace. The three sets of samples were immediately austempered in the austempering salt bath furnace at uniform austempering temperatures of 300 0C, 350 0C and 400 0C for 90, 120 and 150 minutes; each sample for each temperature window. All sets were prepared for metallographic examination; tensile and hardness tests were carried out. The results showed that maximum hardness, tensile and yield strength were obtained at austempering temperature of 350 0C and at 150 minutes. At 300 0C and 350 0C, it was noticed that the hardness and strength increase with austempering time. The optimum tensile strength was 1300 MPa at 350 0C after austempering for 150 minutes. In conclusion the austempering operation has a significant effect on the mechanical and microstructural properties of ADI

Intercropping system: Potential for the control of bean flower thrips with masking of lemongrass and mexican marigold

Cowpea (Vigna unguiculata) is an important food and forage legume in Africa. The bean flower thrips (Megalurothrips sjostedti) is one of the major pests of cowpea in Sub-Saharan Africa, reducing crop yield. Chemical pesticides remain the main control strategy, even with their negative impact on human and environmental health. Intercropping with maize as a visual barrier is commonly used by the smallholder farmers to reduce pest populations on cowpea. The use of host and no-host volatiles is another alternative method to reduce thrips pest populations in IPM strategy. The objective of this study was to evaluate the effect of semiochemical interactions between cowpea and two repellent plants, Cymbopogon citratus and Tagetes minuta, on the behaviour of M. sjostedti. Initially, we evaluated the attractiveness of vegetative parts and flowers of four cowpea varieties (KK1, K80, M66 and eL) to male and female M. sjostedti using Y-tube olfactometer. With the exception of flower of cowpea variety KK1 which were attractive to female M. sjostedti, all the varieties induced repellence or neutral responses to both sexes of the pest. Combination of KK1 flower with either C. citratus cut leaves or T. minuta plant were less attractive than cowpea flower alone (KK1) for females. However, the inhibitory effect of C. citratus cut leaves disappeared after 24hours. Overall, these results highlight the potential of exploiting volatile compounds from repellent plants to reduce M. sjostedti infestation in cowpea cropping systems. (Résumé d'auteur

Investigation of Wear Land and Rate of Locally Made HSS Cutting Tool

Production technology and machining are inseparable with cutting operation playing important roles. Investigation of wear land and rate of cutting tool developed locally (C=0.56%) with an HSS cutting tool (C=0.65%) as a control was carried out. Wear rate test was carried out using Rotopol –V and Impact tester. The samples (12) of locally made cutting tools and one (1) sample of a control HSS cutting tool were weighed to get the initial weight and grit was fixed at a point for the sample to revolve at a specific time of 10 mins interval. Approach of macro transfer particles that involved mechanism of abrasion and adhesion which was termed as mechanical wear to handle abrasion adhesion processes was used in developing equation for growth wear at flank. It was observed from the wear test that best minimum wear rate of 1.09 x10-8 and 2.053x10-8 for the tools developed and control were measured. MATLAB was used to simulate the wear land and rate under different conditions. Validated results of both the experimental and modeling showed that cutting speed has effect on wear rate while cutting time has predicted measure on wear land. Both experimental and modeling result showed best performances of tools developed over the control

The rise of policy coherence for development: a multi-causal approach

In recent years policy coherence for development (PCD) has become a key principle in international development debates, and it is likely to become even more relevant in the discussions on the post-2015 sustainable development goals. This article addresses the rise of PCD on the Western donors’ aid agenda. While the concept already appeared in the work of Organisation for Economic Co-operation and Development (OECD) in the early 1990s, it took until 2007 before PCD became one of the Organisation’s key priorities. We adopt a complexity-sensitive perspective, involving a process-tracing analysis and a multi-causal explanatory framework. We argue that the rise of PCD is not as contingent as it looks. While actors such as the EU, the DAC and OECD Secretariat were the ‘active causes’ of the rise of PCD, it is equally important to look at the underlying ‘constitutive causes’ which enabled policy coherence to thrive well

Widespread range expansions shape latitudinal variation in insect thermal limits

I thank the authors of previous studies on global variation in insect thermal tolerances who have generously provided open access use of their data sets.Peer reviewedPostprin