Effect of incubation temperatures on mycelial growth, conidial features and density of Stemphylium botryosum Walr isolates

The cultural and morphological variability of Stemphylium botryosum Walr was studied with five isolates viz. isolate 1 (Stb-I1), isolate 2 (Stb-I2), isolate 3 (Stb- I3), isolate 4 (Stb-I4) and isolate 5 (Stb-I5) collected from Parsa, Rautahat, Dang, Banke and Chitwan districts of Nepal respectively during 2011-2012 crop season with Completely Randomized Design (CRD) maintaining 3 replications at Plant Pathology Laboratory of Grain Legumes Research Program (GLRP), Rampur, Chitwan. Single spore isolation technique was followed to isolate the pathogen. The pathogen was grow on Potato Dextrose Agar (PDA) and incubated with different temperatures in BOD incubator. The calibrated ocular micrometer was used to measure the length and breadth of the conidia while conidial count with sporulation intensity was attempted with hemocytometer. The mycelium color of the different isolates was varied from white, grey, brown and brownish black in peripheral part while mostly black pigmentation was noticed in lateral part of the culture plate. The shape and texture was regular and velvety for most isolates and in some isolate, roughly irregular shape with cottony texture was found. The higher colony diameter of 7.66 cm and conidial dimension of 29.42×18.12 μm (L/B ratio-1.62) with profuse sporulation intensity (46.67 conidia /0.01 ml) was observed at 25 °C after 15 days of incubation on PDA. However, 2.84 cm diameter, 19.58×9.81 μm (L/B ratio-2.00) with poor conidial density (7.60 conidia /0.01 ml) was noticed at 10 °C. The observation at 10 and 35 °C was at par in case of mycelial growth, conidial features and sporulation intensity. Mostly conidia of all isolates were brown in color at lower incubation temperature but they became dark grey brown at 25 and 30 °C and grey color was noticed when incubated at 35 °C on PDA after 15 days of incubation.Kathmandu University Journal of Science, Engineering and TechnologyVol. 12, No. I, June, 2016, page: 80-89

Validation of developed method by RP-HPLC for simultaneous estimation of famotidine and ibuprofen in human plasma and studying the stability of the drugs in plasma

The RP-HPLC separation was carried out by reverse phase chromatography on a Symmetry C18 (4.6 x 150 mm, 3.5 μm, make: XTerra) with a mobile phase composed of sodium dihydrogen ortho phosphate [pH 2.5] and acetonitrile in the ratio of 30:70 v/v in an isocratic mode at a flow rate of 1.2 mL/min. The run time was maintained for 8.0 min. The detection was monitored at 236 nm. The accuracy was calculated in human plasma and the % recovery was found 99.80 - 99.85 for famotidine and 99.56 -99.85.5 for ibuprofen and reproducibility was found to be satisfactory. The calibration curve for famotidine in human plasma was linear over 3.32 to 6.65 μg/mL and 100- 200 μg/mL for ibuprofen in human plasma respectively. The inter-day and intra-day precision in human plasma was found within limits. The proposed method has adequate sensitivity, reproducibility, and specificity for the determination of famotidine and ibuprofen in plasma. The LLOQ obtained by the proposed method in human plasma were 1.24 and 5.0 μg/mL for famotidine and ibuprofen respectively. The proposed method is simple, fast, accurate, and precise for the quantification of famotidine and ibuprofen in plasma as per the ICH guidelines.Kathmandu University Journal of Science, Engineering and TechnologyVol. 12, No. I, June, 2016, Page: 34-48

A common fixed point theorem for subcompatible mappings in fuzzy metric space

The aim of the present paper is to establish a common fixed point theorem for subcompatible pair of self mappings in a fuzzy metric space which generalizes and improves various well-known comparable results.Kathmandu University Journal of Science, Engineering and TechnologyVol. 12, No. I, June, 2016, Page: 90-98

Free convective flow of a couple stress fluid through a vertical porous channel in the presence of a transverse magnetic field

Nonlinear oberbeck convection of a couple stress fluid in a vertical porous channel in the presence of transverse magnetic field is investigated in this paper. Analytical solution is obtained using the perturbation technique for vanishing values of the buoyancy parameter. Numerical solution of the nonlinear governing equations is obtained using the finite difference technique to validate the results obtained from the analytical solutions. The influence of the physical parameters on the flow, such as couple stress parameter, Hartmann number, temperature parameter, porous parameter and buoyancy parameter are evaluated and presented graphically. A new approach is used to analyse the flow for strong, weak and comparable porosity cases. It is found that increase in porous parameter, couple stress parameter, Hartmann number and temperature parameters decrease the velocity considerably.Kathmandu University Journal of Science, Engineering and Technology Vol. 12, No. I, June, 2016, Page: 49-62

Suitability study of soybeans husk ash as a mixing material to OPC: Effect of calcination time-preliminary investigation

Soybeans husk was collected from a dump site, dried de-carbonated, separated into six samples and calcined at a temperature of 600 °C, for 1, 2, 3, 4, 5 and 6 hours respectively. Samples were taken for X- ray Florescence (XRF) analysis, Standard Electron Microscopy (SEM) imaging, setting time, standard water of consistency determination and specific gravity test. The result of XRF analysis revealed that the SHA contain less than 70 % SiO2+Al2O3+Fe2O3 stipulated by ASTM C618 for pozzolanas, but has very high CaO content. The SiO2 +Al2O3+Fe2O3 and CaO content though varies slightly with the calcination time of soybean husk. The specific gravity of SHA varies with calcination time of SH and ranges between 2.3 and 2.7 and is less than that of OPC irrespective of the calcination time. Setting times of OPC/SHA pastes at 10 % replacement of OPC with SHA increases with calcination time and is greater than that for OPC paste. The SEM analysis shows that the crystal structure of the SHA changes with calcination temperature. The compressive strength of mortar using OPC/SHA as a binder was determined after 7, 14 and 28 days curing and was found to be less than that for OPC mortars at all ages. However, the percentage reduction in strength decreased with curing age, with SHA calcined at 4 hours having the greater strength (i.e. 87.4 % of OPC strength at 28 days). The percentage gain in strength was more pronounced from 7 to 14 days. In all, SH calcined at 600 °C for 4 hours optimizes the pozzolanic potential of SHA.Kathmandu University Journal of Science, Engineering and Technology Vol. 12, No. I, June, 2016, Page: 13-22

Effects of permeability and electric field on nonlinear Oberbeck Electro-convection in a vertical poorly conducting fluid saturated porous channel

The effects of permeability on nonlinear Oberbeck Electro-convection in a poorly conducting fluid saturated porous medium in a vertical channel, when the walls are held at different temperatures with temperature difference perpendicular to gravity, is studied using the modified Navier stokes equation in the presence of both induced and an applied electric field. Both analytical and numerical solutions for the non-linear coupled equations governing the motion are obtained and found that analytical solutions agree well with numerical solutions for values of the buoyancy parameter N <1. It is shown that OBEC can be controlled by maintaining the temperature difference either in the same direction or opposing the potential difference with a suitable value of electric number W. The effect of W on velocity, temperature, rate of heat transfer, skin friction and mass flow rate are computed and the results are depicted graphically. We found that the analytical solutions for velocity and temperature distributions are in close agreement with those obtained from the numerical method for small values of N. We also found that an increase in W accelerates the flow and hence increases linearly the skin friction and mass flow rate. Further, the velocity and temperature have the same behavior for different values of porous parameter when the temperature difference and the potential difference are in the same or in the opposite directions.Kathmandu University Journal of Science, Engineering and Technology Vol. 12, No. I, June, 2016

Physical properties of coconut shell nanoparticles

Physical properties such as apparent density, bulk density, compressibility index and particle sizes of carbonized and uncarbonized coconut shell nanoparticles produced through top down approach have been studied. Percentage composition of the coconut fruit was determined using five different coconut fruit samples. Results revealed that coir occupies the highest percentage; coconut shells account for 15 % while the flesh and liquid occupy 30 % of the whole coconut fruit. The apparent densities of the uncarbonized and carbonized coconut shell nanoparticles obtained at 70 hours of milling are 0.65 g/cm3 and 0.61 g/cm3 respectively. Their respective compressibility indices and average particle sizes are 46.4 % and 69.7 %; 50.01 nm and 14.29 nm. The difference in the particle sizes of the carbonized and uncarbonized coconut shell nanoparticles can be linked with reduction in the moisture content and volatiles of the carbonized coconut shell nanoparticles due to carbonization process. The reduction in the moisture and volatiles results in the enhanced hardness and brittleness of the carbonized coconut shells which facilitate their breakage during the course of milling than that of the uncarbonized coconut shells. Kathmandu University Journal of Science, Engineering and Technology Vol. 12, No. I, June, 2016, Page: 63-79

Formulation and evaluation of orodispersible tablets of dimenhydrinate by using co-processed superdisintegrants

The main objective of this study was to formulate orodispersible tablets of Dimenhydrinate for quick relief of emesis. Orodispersible tablets were prepared by direct compression method using co-processed super-disintegrants. Co-processed super-disintegrants are the mixture of crospovidone and guar gum in different ratios. The powder mixtures and tablets were subjected to various pre-compression and post-compression evaluations. IR spectroscopy showed no interaction between drug and other excipients. Angle of repose and Carr’s index was found in the range of 23.89°-28.27° and 23.29-15.48 respectively. These results indicated that powder mixtures showed good to acceptable flow properties. All formulations containing co-processed super-disintegrant showed short disintegration time (38.23-17.67 s) and maximum water absorption ratio 73.39%-91.35% compared to control formulation (3.54 min wetting time). Among all formulation F7 containing crospovidone: guar gum in 1:3 ratio showed highest percentage of drug release (98.89%) in 30 min, which is due to high degree of swelling caused by guar gum along with rapid hydration of tablets by crospovidone. Formulation F7 was subjected for 3 months of stability studies; results reviled that the tablet formulation was stable throughout the study period. In conclusion the obtained results suggested that orodispersible tablets of Dimenhydrinate with rapid disintegration and fast drug release can be successfully formulated by employing co-processed super-disintegrants. Kathmandu University Journal of Science, Engineering and TechnologyVol. 12, No. I, June, 2016 Page: 23-33

Suitability of Electronic Nose as a Reflective Tool to the Measurement of Soil Fertility Factors

Humic Acid (HA) and Fulvic Acid (FA) contribute prominently to soil fertility. They are aromatic in nature and hence can be determined by sensory array. This is apparently the first report on the employment of Electronic nose (E-nose) to detect HA and FA extracted from soil. The aim was to evaluate the E-nose sensor response to HA and FA chemically extracted from different agricultural soils. Humic acid and Fulvic acid were extracted from collected agricultural soils and the aroma was measured by E-nose from each of the seven soils. Their presence was confirmed by fluorescence spectroscopy. The Norm Aroma Index (NAI) was measured for: soil, soil after heat treatment, heat treated soil amended with extracted HA, heat treated soil amended with extracted FA, extracted HA and extracted FA. The NAI values were descending in the order: heat treated soil amended with extracted HA/FA, extracted HA/FA, soil (untreated) and heat treated soil. This indicates that HA and FA are detected by E-nose. It was also observed that the most sensitive sensors were 2, 3, 4, 8 and 5 for all agricultural soils tested. Out of the eight sensors in the sensory array of E-nose, above mentioned sensors consistently exhibited high response and these sensors when customized into a small unit may act as a soil fertility tester.Kathmandu University Journal of Science, Engineering and TechnologyVol. 13, No. 2, 2017, page: 39-47

Isolation of Phosphate Solubilizing Bacteria and their Use for Plant Growth Promotion in Tomato Seedling and Plant

Phosphorous (P) is an essential macronutrient and most soils contain high levels of P. However, its availability to plant is limited by rapid immobilization of phosphorous compounds to insoluble forms and hence plant available forms of P in soils are found in low amounts. Phosphate solubilizing bacteria provide an eco-friendly alternative to convert insoluble phosphates into plant available forms. In the present study, three phosphate solubilizing bacterial isolates (PB-1, PB-4 and VC-01) with visually significant phosphate solubilizing abilities were isolated from tomato rhizosphere soil. In-vitro study in pikovskaya’s agar revealed that isolate PB-1 had the highest phosphate solubilizing ability with a phosphate solubilizing index of 2.08±0.07 followed by isolate VC-01 (1.31±0.09) and PB-4 (1.24±0.08). Isolates were used as bacterial inoculum to assess their ability to promote tomato (Lycopersicon esculentum var. Srijana) seedling and plant growth in in-vitro and greenhouse experiment respectively. Isolate PB-4 showed best growth promotion in seedling assay whereas isolate PB-1 and VC-01 also promoted seedling growth compared to control. In greenhouse experiment however, isolates VC-01 and PB-1 significantly enhanced all parameters (shoot length, root length, shoot and root dry weight) compared to uninoculated control whereas isolate PB-4 had a positive effect on all parameters except root length.Kathmandu University Journal of Science, Engineering and TechnologyVol. 13, No. 2, 2017, page: 61-70