External electric field effect on electron transport in carbon nanotubes

Electronic transport properties of carbon nanotubes are studied theoretically in the presence of external electric field E(t) by using the Boltzmann's transport with constant relaxation time. An analytical expression for the current densities of the nanotubes are obtained. It is observed that the current density-electric field characteristics of the CNs exhibit total self-induced transparency and absolute negative conductivityComment: 5 pages, 2 figure

The Mectizan(® )Donation Program – highlights from 2005

Through the Mectizan(® )Donation Program, Merck & Co., Inc. has donated Mectizan (ivermectin, MSD) for the treatment of onchocerciasis worldwide since 1987. Mectizan has also been donated for the elimination of lymphatic filariasis (LF) since 1998 in African countries and in Yemen where onchocerciasis and LF are co-endemic; for LF elimination programs, Mectizan is co-administered with albendazole, which is donated by GlaxoSmithKline. The Mectizan Donation Program works in collaboration with the Mectizan Expert Committee/Albendazole Coordination, its scientific advisory committee. In 2005, a total of 62,201,310 treatments of Mectizan for onchocerciasis were approved for delivery via mass treatment programs in Africa, Latin America, and Yemen. Seventy-seven percent and 20% of these treatments for onchocerciasis were for countries included in the African Programme for Onchocerciasis Control (APOC) and the former-Onchocerciasis Control Programme in West Africa (OCP), respectively. The remaining 3% of treatments approved were for the six onchocerciasis endemic countries in Latin America, where mass treatment is carried out twice-yearly with the goal of completely eliminating morbidity and eventually transmission of infection, and for Yemen. All 33 onchocerciasis endemic countries where mass treatment with Mectizan is indicated have ongoing mass treatment programs. In 2005, 42,052,583 treatments of co-administered albendazole and Mectizan were approved for national Programs to Eliminate LF (PELFs) in Africa and Yemen. There are ongoing PELFs using albendazole and Mectizan in nine African countries and Yemen; these represent 35% of the total number of countries expected to require the co-administration of these two chemotherapeutic agents for LF elimination. In Africa, the expansion of existing PELFs and the initiation of new ones have been hampered by lack of resources, technical difficulties with the mapping of LF endemicity, and the co-endemicity of LF and loiasis. Included in this review are recommendations recently put forward for the co-administration of albendazole and Mectizan in areas endemic for LF, loiasis, and onchocerciasis

Does postnatal care have a role in improving newborn feeding? A study in 15 sub–Saharan African countries

Breastfeeding is known as a key intervention to improve newborn health and survival while prelacteal feeds (liquids other than breastmilk within 3 days of birth) represents a departure from optimal feeding practices. Recent programmatic guidelines from the WHO and UNICEF outline the need to improve newborn feeding and points to postnatal care (PNC) as a potential mechanism to do so. This study examines if PNC and type of PNC provider are associated with key newborn feeding practices: breastfeeding within 1 day and prelacteal feeds

Effect of organic fertilizers on physical and chemical quality of sugar loaf pineapple (Ananas comosus L) grown in two ecological sites in Ghana

Pineapple has a large demand for plant nutrients and for this reason; fertilization is almost mandatory where the fruit is destined for sale. As consumer demand for organic food grows, organic production and certification is seen as a valuable alternative for smallholder farmers in developing countries. This study sought to investigate the effects of different organic fertilizers on the physical and chemical quality of pineapple (Ananas comosus L.) cultivated in two different ecological zones in Ghana. Organic fertilizers treatments were POME (Palm oil meal effluent), Phos-K (PH), Yara (Y) and combination of Phos-K and POME (PH+P) and Yara + POME (Y+P) in the ratio of 1:1. Soil without fertilizer was control. A farmer field demonstration and an on-station experimental trial were conducted parallel at Nsakyi and at the Biotechnology and Nuclear Agriculture Research Institute (BNARI) research farm, respectively. The experiment was laid out in the Randomised Completely Block Randomized Design (RCBD) with five fertilizer treatments and four replications. Sugar loaf pineapples were harvested at 17 months upon maturity, washed, peeled, and juice extracted for analyzing vitamin C, Total Soluble Solids, pH, Titratable acidity, juice yield and colour. Fruits were weighed with Sartorius scale and percentage weight loss estimated over 15 days. The weight loss of pineapples treated with POME (25.56 ± 0.62 %) from BNARI farm was significantly (p<0.05) higher than all the other pineapple treaments. pH of all pineapple samples significantly (P<0.05) differed for all the different fertilizer treatments for both farms. Phos-K significantly (p<0.05) enhanced the vitamin C content of pineapples from both ecological sites Lightness (L*) and yellowness (b*) for juice of pineapple treated with Phos-K from BNARI farm was significantly (p<0.05) higher, than samples from Nsakyi farms indicating desirable visual appeal for sugar loaf pineapples. Organic fertilizers significantly (p<0.05) influenced the pH, vitamin C and juice yield of pineapples grown in the two different ecological zones. Irrespective of the ecological differences in Nsakyi and BNARI farm sites, the application of Phos-K to pineapple significantly (p<0.05) increased the juice yield which is a desirable quality of pineapple. Thus the application of Phos-K organic fertilizer, better improved the physical and chemical quality attributes of pineapple. However, there is the need to conduct further work on application rate and utilization efficiency of organic fertilizers that will produce maximum pineapple quality and yield.Keywords: Organic fertilizers, Juice, weight los

Antimycobacterial and cytotoxic activity of selected medicinal plant extracts

AbstractEthnopharmacological relevanceTuberculosis (TB) caused by Mycobacterium tuberculosis remains an ongoing threat to human health. Several medicinal plants are used traditionally to treat tuberculosis in Ghana. The current study was designed to investigate the antimycobacterial activity and cytotoxicity of crude extracts from five selected medicinal plants.Material and methodsThe microplate alamar blue assay (MABA) was used for antimycobacterial studies while the CellTiter 96® AQueous Assay, which is composed of solutions of a novel tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; MTS] and an electron coupling reagent (phenazine methosulfate) PMS, was used for cytotoxic studies. Correlation coefficients were used to compare the activity of crude extracts against nonpathogenic strains and the pathogenic Mycobacterium tuberculosis subsp.tuberculosis.ResultsResults of the MIC determinations indicated that all the crude extracts were active on all the three tested mycobacterial strains. Minimum inhibitory concentration values as low as 156.3µg/mL against M. tuberculosis; Strain H37Ra (ATCC® 25,177™) were recorded from the leaves of Solanum torvum Sw. (Solanaceae). Cytotoxicity of the extracts varied, and the leaves from S. torvum had the most promising selectivity index. Activity against M. tuberculosis; Strain H37Ra was the best predictor of activity against pathogenic Mycobacterium tuberculosis subsp.tuberculosis (correlation coefficient=0.8).ConclusionThe overall results of the present study provide supportive data on the use of some medicinal plants for tuberculosis treatment. The leaves of Solanum torvum are a potential source of anti-TB natural products and deserve further investigations to develop novel anti-TB agents against sensitive and drug resistant strains of M. tuberculosis

Naphthalene-functionalized resorcinarene as selective, fluorescent self-quenching sensor for kynurenic acid†

Kynurenic acid is a by-product of tryptophan metabolism in humans, with abnormal levels indicative of disease. There is a need for water-soluble receptors that selectively bind kynurenic acid, allowing for detection and quantification. We report here the high-affinity binding of kynurenic acid in aqueous media to a resorcinarene salt receptor decorated with four flexible naphthalene groups at the upper rim. Experimental results from 1H NMR, isothermal titration calorimetry, and electronic absorption and fluorescence spectroscopies all support high-affinity binding and selectivity for kynurenic acid over tryptophan. The measured binding constant (K = 1.46 ± 0.21 × 105 M−1) is one order of magnitude larger than that observed with other resorcinarene receptors. The present host–guest system can be employed for sensory recognition of kynurenic acid. Computational studies reveal the key role of a series of cooperative attractive intra- and inter-molecular interactions contributing to an optimal binding process in this system

The observability of galaxy merger signatures in nearby gas-rich spirals

Galaxy mergers are crucial to understanding galaxy evolution, therefore we must determine their observational signatures to select them from large IFU galaxy samples such as MUSE and SAMI. We employ 24 high-resolution idealized hydrodynamical galaxy merger simulations based on the ‘Feedback In Realistic Environment’ (FIRE-2) model to determine the observability of mergers to various configurations and stages using synthetic images and velocity maps. Our mergers cover a range of orbital configurations at fixed 1:2.5 stellar mass ratio for two gas rich spirals at low redshift. Morphological and kinematic asymmetries are computed for synthetic images and velocity maps spanning each interaction. We divide the interaction sequence into three: (1) the pair phase; (2) the merging phase; and (3) the post-coalescence phase. We correctly identify mergers between first pericentre passage and 500 Myr after coalescence using kinematic asymmetry with 66 per cent completeness, depending upon merger phase and the field of view of the observation. We detect fewer mergers in the pair phase (40 per cent) and many more in the merging and post-coalescence phases (97 per cent). We find that merger detectability decreases with field of view, except in retrograde mergers, where centrally concentrated asymmetric kinematic features enhances their detectability. Using a cut-off derived from a combination of photometric and kinematic asymmetry, we increase these detections to 89 per cent overall, 79 per cent in pairs, and close to 100 per cent in the merging and post-coalescent phases. By using this combined asymmetry cut-off we mitigate some of the effects caused by smaller fields of view subtended by massively multiplexed integral field spectroscopy programmes