Adiabatic Heavy Ion Fusion Potentials for Fusion at Deep Sub-barrier Energies

The fusion cross sections from well above barrier to extreme sub-barrier energies have been analysed using the energy (E) and angular momentum (L) dependent barrier penetration model ({\small{ELDBPM}}). From this analysis, the adiabatic limits of fusion barriers have been determined for a wide range of heavy ion systems. The empirical prescription of Wilzynska and Wilzynski has been used with modified radius parameter and surface tension coefficient values consistent with the parameterization of the nuclear masses. The adiabatic fusion barriers calculated from this prescription are in good agreement with the adiabatic barriers deduced from {\small{ELDBPM}} fits to fusion data. The nuclear potential diffuseness is larger at adiabatic limit, resulting in a lower $\hbar\omega$ leading to increase of "logarithmic slope" observed at energies well below the barrier. The effective fusion barrier radius and curvature values are anomalously smaller than the predictions of known empirical prescriptions. A detailed comparison of the systematics of fusion barrier with and without L-dependence has been presented.Comment: Revtex file of 6 pages and 3 eps figure

Total cross sections for neutron-nucleus scattering

Systematics of neutron scattering cross sections on various materials for neutron energies up to several hundred MeV are important for ADSS applications. Ramsauer model is well known and widely applied to understand systematics of neutron nucleus total cross sections. In this work, we examined the role of nuclear effective radius parameter (r$_0$) on Ramsauer model fits of neutron total cross sections. We performed Ramsauer model global analysis of the experimental neutron total cross sections reported by W. P. Abfalterer, F. B. Bateman, {\it et. al.,}, from 20MeV to 550MeV for nuclei ranging from Be to U . The global fit functions which can fit total cross section data over periodic table are provided along with the required global set of parameters. The global fits predict within $\pm 8$ deviation to data, showing the scope for improvement. It has been observed that a finer adjustment of r$_0$ parameter alone can give very good Ramsauer model description of neutron total scattering data within $\pm 4$ deviation. The required r$_0$ values for Ramsauer model fits are shown as a function of nuclear mass number and an empirical formula is suggested for r$_0$ values as a function of mass number. In optical model approach for neutron scattering, we have modified the real part of Koning-Deleroche potentails to fit the neutron total cross sections using SCAT2 code. The modified potentails have a different energy dependence beyond 200MeV of neutron energy and fit the total cross sections from Al to Pb.Comment: 9 pages, 20figures, Poster number ND-1457, ND2010 Conference in Kore

The Effect of Oxidation on the Tribological Performance of Few Vegetable Oils

BackgroundThe use of vegetable oils and their derivatives as lubricant base oils are ever increasing because of sustainability issues and in the context of conservation of nature as they are biodegradable and environmentally friendly. The one disadvantage which is of concern with vegetable oils is their limited oxidative stability.ObjectivesTo study the effect of oxidation on the tribological performance of few vegetable oils by subjecting the oil samples to accelerated ageing in a dark oven at different temperatures, inducing the oxidation under controlled conditions.MethodOils were stored at an elevated temperature in an oven under dark condition and the oxidized oil samples were analyzed in terms of various properties.Results and conclusionsThe samples were analyzed for the changes in viscosity, percentage of free fatty acid, peroxide number and were compared with fresh oils samples. Further tribological property was also evaluated and the observed differences were linked to formation of oxidation products like peroxides, kinetics of the oxidation with reference to ageing temperature

Evaporation of alpha particles from 31^31P nucleus

The energy spectra of alpha particles have been measured in coincidence with the evaporation residues for the decay of the compound nucleus $^31$P produced in the reaction $^19$F (96 MeV) + $^12$C. The data have been compared with the predictions of the statistical model code CASCADE. It has been observed that significant deformation effect in the compound nucleus need to be considered in order to explain the shape of the evaporated alpha particle energy spectra.Comment: 4 pages, 3 figures, revtex, epsf styl

Effect of melt extrudability and melt binding efficiency of polyvinyl caprolactam polyvinyl acetate polyethylene glycol graft copolymer (Soluplus®) on release pattern of hydrophilic and high dose drugs

The present study explores the effect of melt binding of Soluplus® on in vitro release profiles of two hydrophilic drugs, metformin hydrochloride, and paracetamol. The melt viscosities of bulk polymer and physical mixtures with different concentrations of selected APIs were analyzed by using a rheometer. The rheological evaluation revealed both the suitable temperature range for melt extrusion process and drug-polymer extrudability. The effect of formulation and processing parameters (e.g. polymer/drug ratio, temperature, screw speed) on extrudability were evaluated in terms of torque and residence time analysis. The extrudates obtained via hot melt extrusion (HME) processing exhibited good flow and compressibility. Differential scanning calorimetry (DSC) and X-ray diffraction studies examined the change in glass transition temperature (Tg) and crystalline pattern of extruded formulations where all extruded formulations seemed to have retained their crystallinity. The thermogravimetric analysis determined the thermal stability (weight loss) as a function of operating temperature whereas scanning electron microscopy (SEM) showed agglomerated microstructure and rough surface with a porous network and void spaces. The tablets obtained after compression of milled extrudates showed excellent hardness with robust tablet characteristics. The in vitro release studies of individual batches performed in various USP recommended dissolution media (for paracetamol) showed the pH-independent release of the hydrophilic drugs from the polymer matrices

Evaluation of interface microstructure for friction stir welded aluminium-stainless steel plate

In the present study, commercially pure aluminium has been joined with 304 stainless steel by friction stir welding. Microstructural characterization was carried out using scanning and transmission electron microscopes. Diffusion of Fe, Cr and Ni is substantial within Al; however diffusion of Al within 304SS is limited. Owing to inter-diffusion of chemical species across the bond line, discrete islands of Fe3Al intermetallic phase forms within the reaction zone. The rubbing action of tool over the butting edge of 304SS removed fine particles of 304SS and got embedded in the stirring zone of Al matrix. At the latter stage austenite underwent phase transformation to ferrite due to large strain within its grain. Fracture path mainly moves through stirring zone of Al alloy under tensile loading; however in some places, presence of Fe3Al compound has been found