Role of NGOs in irrigation development and management in Nepal: Proceedings of the National Workshop on the Role of NGOs in Irrigation Development and Management in Nepal, Nepal Administrative Staff College, Jawalakhel, Lalitpur, Nepal, 29-30 September 1992

Agricultural manpower / Non-governmental organizations / Rural development / Irrigation management / Nepal

Propane dehydrogenation on single site gallium on silica catalyst

Light alkane dehydrogenation is gaining increasing importance due to the discovery of shale gas. Gallium based catalysts such as Ga/HZSM-3 and Ga2O3 have been used to dehydrogenate propane to propylene. However, the exact nature of the active site for propane dehydrogenation on Gallium based catalysts is still debated in literature. This work is aimed at understanding the nature of active site in Ga/SiO2 catalyst for propane dehydrogenation. The Ga/SiO2 catalyst is active and selective for propane dehydrogenation reaction. It is shown that Ga +3 site co-ordinated with four O atoms is the most active form of Gallium during the propane dehydrogenation reaction. The catalyst is subjected to different pretreatment conditions and it is observed that the pretreatment with H2 at 650°C results in lower initial rates for propane dehydrogenation. The Ga/SiO2 catalyst is studied using operando X-Ray Absorption Spectroscopy, in-situ Fourier Transform Infrared Spectroscopy and X-Ray Photoelectron Spectroscopy. Reduction of the catalyst at 650°C resulted in the formation of a reduced Gallium species which results in lower rates of propane dehydrogenation. These reduced Gallium species were found to be unstable under conditions of propane dehydrogenation and get reoxidized to Ga+3. It is proposed that the reduced Gallium species has the form of Gallium hydride which is less active for propane dehydrogenation

From farmers' fields to data fields and back: A Synthesis of Participatory Information Systems for Irrigation and other Resources: Proceedings of an International Workshop held at the Institute of Agriculture and Animal Science, Rampur, Nepal, 21-26 March 1993

Irrigation / Forestry / Natural resources / Farmer participation / Participatory rural appraisal / Rapid rural appraisal / GIS / Data collection / Databases / Field tests / Farmers' associations / Training / Water rights / Water law / Institutions / Non-governmental organizations / India / Nepal

Queue Length and Server Content Distribution in an Infinite-Buffer Batch-Service Queue with Batch-Size-Dependent Service

We analyze an infinite-buffer batch-size-dependent batch-service queue with Poisson arrival and arbitrarily distributed service time. Using supplementary variable technique, we derive a bivariate probability generating function from which the joint distribution of queue and server content at departure epoch of a batch is extracted and presented in terms of roots of the characteristic equation. We also obtain the joint distribution of queue and server content at arbitrary epoch. Finally, the utility of analytical results is demonstrated by the inclusion of some numerical examples which also includes the investigation of multiple zeros

Dynamics of Magnetized Bulk Viscous Strings in Brans-Dicke Gravity

We explore locally rotationally symmetric Bianchi I universe in Brans-Dicke gravity with self-interacting potential by using charged viscous cosmological string fluid. We use a relationship between the shear and expansion scalars and also take the power law for scalar field as well as self-interacting potential. It is found that the resulting universe model maintains its anisotropic nature at all times due to the proportionality relationship between expansion and shear scalars. The physical implications of this model are discussed by using different parameters and their graphs. We conclude that this model corresponds to an accelerated expanding universe for particular values of the parameters.Comment: 17 pages, 6 figure

DEVELOPMENT AND VALIDATION OF A STABILITY INDICATING RP-HPLC METHOD FOR THE DETERMINATION OF VALSARTAN

Objective: A stability indicating RP-HPLC method was developed and validated for the determination of Valsartan using Telmisartan (10 µg/ml) as the internal standard.Methods: In this procedure Phenomenex ODS C-18(250×4.6 mm, packed with 5 micron) column was used with a new mobile phase consisting of methanol: acetonitrile: water (70:15:15 v/v) and the pH was adjusted to 3 by 0.1% glacial acetic acid with a flow rate of 1 ml/min. The eluents were monitored at 249 nm. Valsartan was subjected to stress conditions including hydrolytic degradation in acidic, basic and neutral conditions, oxidation, photolytic, UV degradation and thermal degradation.Results: Linearity was obtained in the concentration range of 10-90 µg/ml (R2 =0.999) and with a regression equation y=0.074x+0.005. The LOD and LOQ values were 0.261 and 0.791 µg/ml respectively. The drug had shown promising degradation in the acidic, basic, neutral, thermal and oxidative stress conditions.Conclusion: The method was validated for accuracy, precision, linearity, specificity and robustness and revealed that it is specific, accurate, rapid, precise, reliable and reproducible enough to analyze commercial dosage forms as per ICH guidelines

Effect of Conveying and Distributive Mixing Elements on Breakage Phenomenon in Twin Screw Granulation

Twin screw wet granulation (TSG) is gaining more attention and becoming an important process in the pharmaceutical industry. The process is widely implemented because of its flexibility, short residence time, and small equipment footprint. Past studies have shown that screw elements can have a significant impact on the performance of the TSG process. In addition, these studies identified that breakage of wet mass is a significant step in the process. Currently there is no literature that focuses on the effect of each screw element on the breakage process. In this work, experiments have been designed to isolate the breakage process and study the different breakage effects between distributing mixing elements (DMEs) and conveying elements (CEs) in TSG. Cylindrical pellets were made using different model materials having a wide range of dynamic yield strength. The pellets were fed into the twin screw granulator, which then passed through the different screw elements. Pellet breakage probabilities were measured for each screw element configuration. As the strength of the pellets increases, the breakage probability in the CEs decreases. The breakage probability in the DMEs remains the same and shows 100% breakage, independent of the material strength. The experiments have aided in the understanding of the different breakage processes using CEs and DMEs. The breakage in CEs shows a strong dependence on material dynamic yield strength whereas the breakage in DMEs is not a function of the strength

A Large Blue Shift of the Biexciton State in Tellurium Doped CdSe Colloidal Quantum Dots

The exciton-exciton interaction energy of Tellurium doped CdSe colloidal quantum dots is experimentally investigated. The dots exhibit a strong Coulomb repulsion between the two excitons, which results in a huge measured biexciton blue shift of up to 300 meV. Such a strong Coulomb repulsion implies a very narrow hole wave function localized around the defect, which is manifested by a large Stokes shift. Moreover, we show that the biexciton blue shift increases linearly with the Stokes shift. This result is highly relevant for the use of colloidal QDs as optical gain media, where a large biexciton blue shift is required to obtain gain in the single exciton regime.Comment: 9 pages, 4 figure

Structural and optical properties of graphene oxide prepared by modified hummers' method

Graphene oxide was synthesized from graphite flakes using modified Hummers' method. The interlayer spacings of graphite, graphite oxide and graphene oxide were measured using X-ray diffraction technique. The C/O atomic ratios of graphite oxide and graphene oxide were calculated from XPS measurements. The transformation of graphite to graphite oxide and finally to graphene oxide was clearly observed from the micro-Raman spectroscopy data and was confirmed from the FESEM micrographs. UV-VIS-NIR spectrophotometer was used to study the absorbance of graphene oxide and reduced graphene oxide samples. Finally, the chemically reduced graphene oxide was heat-treated in air to obtain chemically modified graphene