ANTIBACTERIAL ACTIVITY OF TABERNAEMONTANA DIVARICATA (APOCYNACEAE) SECONDARY METABOLITES CAPPED SILVER AND GOLD NANOPARTICLES

Objective: To study the antibacterial activity of Tabernaemontana divaricata (Apocynaceae) secondary metabolites capped silver nanoparticles(SNPs) and gold nanoparticles (AuNPs).Methods: In the present investigation, SNPs and AuNPs were synthesized using an aqueous extract of T. divaricata leaves. Leaf aqueous extractwas mixed with 1 mM silver nitrate and chloroauric acid for the biosynthesis of nanoparticles, and the same was analyzed using ultraviolet-visible(UV-Vis) spectrophotometer and particle size analyzer. The antibacterial activity of SNPs and AuNPs was determined against various bacterial culturesincluding laboratory isolates using the agar well diffusion method.Results: The results recorded from UV-Vis spectrum supported the biosynthesis and characterization of SNPs and AuNPs. The SNPs when comparedto AuNPs, showed the highest antibacterial activity against Gram-positive and Gram-negative bacteria.Conclusion: The present study envisions on the biosynthesis of SNPs from T. divaricata plant which are emerging as antibacterial therapy in modernmedical applications.Keywords: Antibacterial activity, Gold nanoparticles, Silver nanoparticles, Tabernaemontana divaricata

An investigation into the effect of rate of stirring of bath electrolyte on the properties of electrodeposited CdTe thin film semiconductors

Electrodeposition (ED) has been recognized as a low cost and scalable technique available for fabrication of CdS/CdTe solar cells. Photovoltaic activity of these electrodeposited semiconductor materials drastically depends on the ED growth parameters namely; electrodeposition potential, concentrations and ratios of concentrations of precursors used to prepare the bath electrolyte, pH of the electrolyte, deposition temperature and rate of stirring of the electrolyte. In order to grow thin films with good photovoltaic properties, it is essential to maintain these variables at their optimum ranges of values during electrodepositions. Hence, this study was conducted to investigate the dependence of the properties of electrodeposited CdTe thin film material on the rate of stirring of the bath electrolyte. The CdTe material was grown on glass/FTO (23 cm2) and glass/FTO/CdS (23 cm2) surfaces in bath electrolytes containing 1.0 mol/L CdSO4 and 1.0 mmol/L TeO2 solutions at different rates of stirring within the range of 0-350 rpm while keeping the values of pH of the electrolyte, deposition temperature and cathodic deposition potential with respect to the saturated calomel electrode at 2.3, 65 °C and 650 mV respectively. After the heat treatment at 400 °C in air atmosphere, the deposited samples with a good visual appearance were selected and evaluated based on their morphological, elemental, structural, optical and electrical properties in order to identify the optimum range of rate of stirring for electrodeposition of CdTe thin film semiconductors. Results revealed that, rates of stirring in the range of 60-85 rpm in a 100 mL volume of electrolyte containing the substrate and the counter electrodes in the center of the bath with a separation of 2.0 cm between them can electrodeposit CdTe layers exhibiting required levels of morphological, structural, optical and electrical properties on both glass/FTO and glass/FTO/CdS surfaces

The dominant Anopheles vectors of human malaria in the Asia-Pacific region: occurrence data, distribution maps and bionomic précis

<p>Abstract</p> <p>Background</p> <p>The final article in a series of three publications examining the global distribution of 41 dominant vector species (DVS) of malaria is presented here. The first publication examined the DVS from the Americas, with the second covering those species present in Africa, Europe and the Middle East. Here we discuss the 19 DVS of the Asian-Pacific region. This region experiences a high diversity of vector species, many occurring sympatrically, which, combined with the occurrence of a high number of species complexes and suspected species complexes, and behavioural plasticity of many of these major vectors, adds a level of entomological complexity not comparable elsewhere globally. To try and untangle the intricacy of the vectors of this region and to increase the effectiveness of vector control interventions, an understanding of the contemporary distribution of each species, combined with a synthesis of the current knowledge of their behaviour and ecology is needed.</p> <p>Results</p> <p>Expert opinion (EO) range maps, created with the most up-to-date expert knowledge of each DVS distribution, were combined with a contemporary database of occurrence data and a suite of open access, environmental and climatic variables. Using the Boosted Regression Tree (BRT) modelling method, distribution maps of each DVS were produced. The occurrence data were abstracted from the formal, published literature, plus other relevant sources, resulting in the collation of DVS occurrence at 10116 locations across 31 countries, of which 8853 were successfully geo-referenced and 7430 were resolved to spatial areas that could be included in the BRT model. A detailed summary of the information on the bionomics of each species and species complex is also presented.</p> <p>Conclusions</p> <p>This article concludes a project aimed to establish the contemporary global distribution of the DVS of malaria. The three articles produced are intended as a detailed reference for scientists continuing research into the aspects of taxonomy, biology and ecology relevant to species-specific vector control. This research is particularly relevant to help unravel the complicated taxonomic status, ecology and epidemiology of the vectors of the Asia-Pacific region. All the occurrence data, predictive maps and EO-shape files generated during the production of these publications will be made available in the public domain. We hope that this will encourage data sharing to improve future iterations of the distribution maps.</p

Case Report - Dysmyelinating neuropathy in benign form of megalencephalic leukoencephalopathy with subcortical cysts: A novel observation from south India

A 37-year-old gentleman presented with macrocephaly since early childhood and progressive impairment of motor and cognitive functions. Magnetic resonance imaging revealed extensive white matter involvement and frontotemporal subcortical cysts. Absent ankle jerk and abnormal nerve conduction study raised a possibility of associated peripheral neuropathy. Sural nerve biopsy was suggestive of dysmyelinating neuropathy. This report serves to expand the clinical spectrum of this rare leukodystrophy