First principles design of divacancy defected graphene nanoribbon based rectifying and negative differential resistance device

We have elaborately studied the electronic structure of 555-777 divacancy (DV) defected armchair edged graphene nanoribbon (AGNR) and transport properties of AGNR based two-terminal device constructed with one defected electrode and one N doped electrode, by using density functional theory and non-equilibrium Green's function based approach. The introduction of 555-777 DV defect into AGNRs, results in a shifting of the {\pi} and {\pi}* bands towards the higher energy value which indicates a shifting of the Fermi level towards the lower energy. Formation of a potential barrier, very similar to that of conventional p-n junction, has been observed across the junction of defected and N doped AGNR. The prominent asymmetric feature of the current in the positive and negative bias indicates the diode like property of the device with high rectifying efficiency within wide range of bias voltages. The device also shows robust negative differential resistance (NDR) with very high peak-to-valley ratio. The analysis of the shifting of the energy states of the electrodes and the modification of the transmission function with applied bias provides an insight into the nonlinearity and asymmetry observed in the I-V characteristics. Variation of the transport properties on the width of the ribbon has also been discussed.Comment: 28 Pages, 12 Figures and 1 tabl

Study of Phytochemical, Anti-Microbial, Anti-Oxidant, Phytotoxic, and Immunomodulatory Activity Properties of Bauhinia Variegata

There is growing interest in the use plants for the treatment and prevention of cancer and are currently being evaluated as promising anticancer agents. In this paper, we investigated the anti-microbial, anti-oxidant, phytotoxic and immunomodulatory of plant Bauhinia variegata and also established the presence of important phytoconstituents which might signify its anticancer property. Phytochemical screening, anti-microbial assay, phytotoxicity assay, anti-oxidant assay and immunomodulatory analysis was done according to the protocol established at Department of Biotechnology, Kathmandu University and Panjwani Center for Molecular Medicine and Drug Research, University of Karachi, Pakistan.In the phytochemical screening, we observed the presence of different phytochemicals like steroids, terpenoids, flavonoids, reducing sugars and glycosides. In case of Antimicrobial assay, the plant was found to be most effective against B.cereus with the highest zone of inhibition (ZOI) of 12mm and against Rhizopus with ZOI of 11mm. During the antioxidant assay in comparison to Ascorbic acid; at highest concentration, the scavenging activity shown by the plant Bauhinia variegata are 43.38% as compared to ascorbic acid 89.25%. In the Immunomodulatory assay at the highest concentration i.e. 250 µg/ml, the plant showed 75.1% effect, which showed that the plant has potential anti-inflammatory potential. In phytotoxicity assay, Bauhinia variegata showed 20% phytotoxicity. Bauhinia variegata has thus been proven to be an important candidate to be used as an antimicrobial, antioxidant, anti-inflammatory, phytotoxic and anticancer agent. Separation of pure compounds with bioassay guided extraction, spectrometric analysis and subsequent cytotoxicity assay of the pure bioactive compounds from Bauhinia variegate is highly recommended as crude extract itself showed promising phytotoxicity and other pharmaceutical potential

Coffee Production in Kavre and Lalitpur Districts, Nepal

Coffee (Coffea spp) is an important and emerging cash crop having potential to provide farmers employment and income generation opportunities. This crop is well adapted to the climatic conditions of mid-hills of Nepal. Thus, majority of the farmers are attracted towards cultivation of coffee because of demands in national and International market. Coffee is now becoming integral part of farming system in rural areas. However, information on performance of coffee and farmers response has not been well documented. Therefore, we undertook the present work to analyze demography, ethnicity, household occupation, literacy status, average land holding, coffee cultivation area, livelihood and sources of income of coffee growers, production and productivity, pricing, cropping pattern of the coffee and problesm faced by them in mid hill district of Kavrepalanchowk (hereafter ‘Kavre') and Lalitpur Districts. All the samples were taken randomly and selected from coffee producing cooperative of Kavre and Lalitpur. Our analysis showed that the male farmer dominant over female on adopting coffee cultivation in both districts with higher value in Kavre. Brahmin and Chetri ethnic communities were in majority over others in adopting the coffee cultivation. Literate farmers were more dominant over illiterates on adopting the coffee cultivation, The mean land holding was less, ranging from 0.15 to 2.30 ha for coffee cultivation, the history of coffee cultivation in Kavre showed that highest number of farmers were engaged in coffee farming from last 16 years. The mean yield of fresh cherry was 1027.20 kg/ha in Kavre, while it was 1849.36 kg/ha in Lalitpur. The study revealed that majority of the coffee plantations were between 6-10 years old. The major problems facing by coffee farmers were diseases spread, lack of irrigation facility and drying of plants. Despite of that the coffee farming was one of the rapidly emerging occupations among the farmers in both district of Nepal