Thermal Convective Instability in an Oldroyd-B Nanofluid Saturated Porous Layer

The onset of convective instability in a layer of porous medium saturated by the Oldroyd-B viscoelastic nanofluid heated from below is investigated by incorporating the effects of Brownian diffusion and thermophoresis. The flux of volume fraction of nanoparticles is taken to be zero on the boundaries. The resulting eigenvalue problem is solved numerically using the Galerkin method. The onset of convective instability is oscillatory only if the strain retardation parameter is less than the stress relaxation parameter and also when the strain retardation parameter does not exceed a threshold value which in turn depends on other physical parameters. The oscillatory onset is delayed with increasing strain retardation parameter, while an opposite trend is noticed with increasing stress relaxation parameter. The effect of increasing modified diffusivity ratio, concentration Darcy–Rayleigh number, modified particle density increment and Lewis number is to hasten the onset of stationary and oscillatory convection and also to decrease the ranges of the strain retardation parameter within which oscillatory convection is preferred

Measurement of absorbed dose rate of gamma radiation for lead compounds

An attempt has been made to estimate the absorbed dose rate using both theoretical and measured mass energy attenuation coefficient of gamma for the lead compounds such as PbNO3, PbCl2, PbO2 and PbO using various gamma sources such as 22Na (511, 1274), 137Cs (661.6), 54Mn (835) and 60Co (1173, 1332 keV). © 2009 Elsevier B.V

Response of Beet Root Tubers to Gypsum, P Levels, Boron and Iron Sulphate in Salt-Affected Soils

A field-experiment was conducted in salt-affected soils of Dodda Seebi tank command area of Tumkur district, Karnataka during rabi season of 2007 to study effect of gypsum, P level, borax and iron sulphate on beet root tuber yield and nutrient uptake. Treatments included two main-plot treatments, viz., M0: Control (without gypsum) and M1: gypsum application @ 9.0 t ha-1 and eight sub-plot treatments, viz., S1: Phosphorus @ 100 kg P2O5 ha-1, S2: Phosphorus @ 150 kg P2O5 ha-1, S3: S1 + Borax @ 5 kg ha-1, S4: S2 + Borax @ 5 kg ha-1, S5: S1 + FeSO5 @ 25 kg ha-1, S6: S2 + FeSO4 @ 25 kg ha-1, S7: S3 + FeSO4 @ 25 kg ha-1 and S8: S4 + FeSO4 @ 25 kg ha-1. Recommended N and K were applied to all treatments. The experiment was laid out in split plot design with three replications. Beet root, a salt-tolerant crop, was sown for testing its performance in salt-affected soils. Significantly higher tuber yield of 12.70 t ha-1 was realized when the crop received gypsum @ 9.0 t ha-1 compared to control (7.73 t ha-1), besides higher nutrient uptake by the tubers. Among the nutrients, application of P at higher level (150 kg P2O5 ha-1) plus recommended NK along with borax and iron sulphate realized higher tuber yield (15.72 t ha-1) as well as nutrients uptake by tubers. Crop that received gypsum in combination with P at a higher level plus recommended NK, along with borax and iron sulphate, resulted in highest tuber yield (19.72 t ha-1) and nutrient uptake

Cl, K and Ni induced reactions to synthesis SHN 273Rg

267-270We have studied chlorine (Cl), potassium (K) and Nickel (Ni) induced reactions in the synthesis of 273Rg. We have studied the compound nucleus formation probability, survival probability and evaporation residue cross sections to synthesize superheavy element (SHN) 273Rg. The selected projectile-target combinations to synthesis 273Rg are 35,37Cl + 238,236Pu, 39-41K + 234-232U and 63,64Ni + 210,209Bi. From the study of PCN, Psur and σevr we have identified that 35Cl+238Pu is the most suitable projectile-target combination to synthesize 273Rg. We have also compared the present work with the experimental values available in literature

Hydrothermal synthesis of Gd2O3:Eu3+ nanophosphors: Effect of surfactant on structural and luminescence properties

Various morphologies of Eu3+ activated gadolinium oxide have been prepared by hydrothermal method using hexadecylamine (HDA) as surfactant at different experimental conditions. The powder X-ray diffraction studies reveal as-formed product is hexagonal Gd(OH)(3):Eu3+ phase and subsequent heat treatment at 350 and 600 degrees C transforms to monoclinic GdOOH:Eu3+ and cubic Gd2O3:Eu3+ phases respectively. SEM pictures of without surfactant show irregular shaped rods along with flakes. However, in the presence of HDA surfactant, the particles are converted into rods of various sizes. The temperature dependent morphological evolution of Gd2O3:Eu3+ without and with HDA surfactant is studied. TEM micrographs of Gd(OH)(3):Eu3+ sample with HDA confirms smooth nanorods with various diameters in the range 20-100 nm. FTIR studies reveal that HDA surfactant plays an important role in conversion of cubic to hexagonal phases. Among these three phases, cubic phase Gd2O3:Eu3+ (lambda(ex) = 254 nm) show red emission at 612 nm corresponding to D-5(0)-> F-7(2) and is more efficient host than the monoclinic counterpart. The band gap for hexagonal Gd(OH)(3):Eu3+ is more when compared to monoclinic GdOOH:Eu3+ and cubic Gd2O3:Eu3+. (C) 2013 Elsevier B. V. All rights reserved

Effect of Li+-​ion on enhancement of photoluminescence in Gd2O3:Eu3+ nanophosphors prepared by combustion technique

Gd2O3:Eu3+ (4 mol​%) nanophosphor co-​doped with Li+ ions have been synthesized by low-​temp. soln. combustion technique in a short time. Powder X-​ray diffractometer (PXRD)​, SEM, Fourier transform IR spectroscopy (FT-​IR)​, UV-​VIS and photoluminescence (PL) techniques have been employed to characterize the synthesized nanoparticles. It is found that the lattice of Gd2O3:Eu3+ phosphor transforms from monoclinic to cubic as the Li+-​ions are doped. Upon 254 nm excitation, the phosphor showed characteristic luminescence 5D0 → 7FJ (J = 0-​4) of the Eu3+ ions. The electronic transition located at 626 nm (5D0 → 7F2) of Eu3+ ions was stronger than the magnetic dipole transition located at 595 nm (5D0 → 7F1)​. Furthermore, the effects of the Li+ co-​doping as well as calcinations temp. on the PL properties have been studied. The results show that incorporation of Li+ ions in Gd2O3:Eu3+ lattice could induce a remarkable improvement of their PL intensity. The emission intensity was obsd. to be enhanced four times than that of with out Li+-​doped Gd2O3:Eu3+

Synthesis, characterization and photoluminescence properties of Gd 2O3:Eu3 nanophosphors prepared by solution combustion method

Gd2O3:Eu3 (0.58.0 mol) nanophosphors have been prepared by low temperature solution combustion method using metal nitrates as oxidizers and oxalyl dihydrazide (ODH) as a fuel. The phosphors are well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence (PL) techniques. PXRD patterns of as-formed and calcined (800 °C, 3 h) Gd2O3 powders exhibit monoclinic phase with mean crystallite sizes ranging from 20 to 50 nm. Eu3 doping changes the structure from monoclinic to mixed phase of monoclinic and cubic. SEM micrographs shows the products are foamy, agglomerated and fluffy in nature due to the large amount of gases liberated during combustion reaction. Upon 254 nm excitation the photoluminescence of the Gd2O3:Eu 3 particles show red emission at 611 nm corresponding to 5D0â7F2 transition. It is observed that PL intensity increases with calcination temperature. This might be attributed to better crystallization and eliminates the defects, which serve as centers of non-radiative relaxation for nanomaterials. It is observed that the optical energy gap (Eg) is widened with increase Eu3 content. © 2010 Elsevier B.V. All rights reserved

IN VITRO INHIBITORY ACTIVITY OF MEDICINAL PLANTS AGAINST PHOMOPSIS AZADIRACHTAE, THE INCITANT DIE BACK DISEASE OF NEEM

Objectives: Plant diseases extend a threat to the global production of herbal medicines. Safer plant protection strategies are in need to meet the demands from the pharmaceutical industry. Neem is a tree with great medicinal values, which is being infected by Phomopsis azadirachtae (PA), causing die back disease. The resulting massive destruction of the tree demands optimum disease management methods and thus, the objective of the present study was to evaluate the inhibitory potential of some plant extracts against the growth of PA.Methods: In this study, we investigate the in vitro antifungal activity of ether: chloroform (1:1), ethyl acetate, acetone and ethanol extracts from different parts (leaves and roots) of five plant species viz., Ocimum tenuiflorium, Centella asiatica, Solanum nigrum, Apium graveolens and Besella alba against the growth of PA.Results: All the 40 crude extracts (at concentration of 1000 μg/ml), were active against PA. Among them, the ethanol and ethyl acetate extracts proved optimum with antifungal activity ranging from 65-95% and minimum inhibitory concentration (MIC) values from 75-200 μg/ml. The antifungal activity of the extracts was in the order: ethanol>ethyl acetate>acetone>ether: chloroform (1:1). Also, noteworthy results were observed in all the extracts tested against the spore germination of PA, with concentration and time-dependent kinetics.Conclusion: The results prove promising in order to develop new antifungal agents against the growth and spread of PA.Â