SH waves due to a point source in an inhomogeneous medium

The propagation of SH waves due to a point source in an homogeneous medium lying over an inhomogeneous substratum has been investigated in this paper. The Green's function technique developed by Ghosh has been used to solve the problem.     

Effect of irregularity and heterogeneity on the stresses produced due to a normal moving load on a rough monoclinic half-space

The present study aims to study the normal and shear stresses produced in a rough irregular heterogeneous monoclinic half-space due to a normal moving load. Closed form expressions of normal and shear stresses have been obtained. It is observed that both normal stress and shear stress are affected not only by depth, the frictional coefficient on a rough surface, and the maximum depth of irregularity but also by the heterogeneity and types of irregularity in the medium. The comparative study has been made to analyze the effect of different types of irregularity on both the stresses. There is a significant effect of depth, frictional coefficient, heterogeneity, maximum depth of irregularity and irregularity factor on the normal and shear stresses in both heterogeneous monoclinic and heterogeneous isotropic medium. A comparison is made to study the effects of the said parameters on the normal and shear stress produced in both heterogeneous medium. These effects are highlighted and depicted by means of graphs. As a special case of the problem, the stress produced due to normal moving load in an isotropic half-space with and without heterogeneity, irregularity has been discussed.     

On the Stability and Thermodynamics of the Dark Energy Based on Generalized Uncertainty Principle

The new agegraphic Dark Energy (NADE) model (based on generalized uncertainty principle) interacting with Dark Matter (DM) is considered in this study via power-law form of the scale factor a(t). The equation of state (EoS) parameter ω _G is observed to have a phantom-like behaviour. The stability of this model is investigated through the squared speed of sound $v_{s}^{2}$ . It is found that $v_{s}^{2}$ always stays at negative level. This indicates instability of the considered model. Moreover, validity of the generalized second law of thermodynamics has been investigated assuming that the apparent horizon is the enveloping horizon. It has been observed that the generalized second law is valid throughout the evolution of the universe.     

Disorder trapping and grain refinement during solidification of undercooled Fe–18 at% Ge melts

The electromagnetic levitation technique has been used to systematically study microstructure evolution and growth rate as a function of undercooling in concentrated Fe–18 at% Ge alloy. The samples are undercooled to a maximum of 240?K. Growth-rate analysis and transmission electron microscopy reveal that, beyond an undercooling of 120?K, the primary phase to solidify is disordered. Microstructural investigations show a decrease in grain size with increasing undercooling. Orientation-imaging microscopy using electron back-scattered diffraction (EBSD) and microhardness measurements have been used to show that recovery and recrystallization play a significant role in the evolution of final microstructure. Microstructural evolution has also been discussed in light of current models of dendrite growth and grain refinement.     

Paradox of enrichment: A fractional differential approach with memory

The paradox of enrichment (PoE) proposed by Rosenzweig [M. Rosenzweig, The paradox of enrichment, Science 171 (1971) 385–387] is still a fundamental problem in ecology. Most of the solutions have been proposed at an individual species level of organization and solutions at community level are lacking. Knowledge of how learning and memory modify behavioral responses to species is a key factor in making a crucial link between species and community levels. PoE resolution via these two organizational levels can be interpreted as a microscopic- and macroscopic-level solution. Fractional derivatives provide an excellent tool for describing this memory and the hereditary properties of various materials and processes. The derivatives can be physically interpreted via two time scales that are considered simultaneously: the ideal, equably flowing homogeneous local time, and the cosmic (inhomogeneous) non-local time. Several mechanisms and theories have been proposed to resolve the PoE problem, but a universally accepted theory is still lacking because most studies have focused on local effects and ignored non-local effects, which capture memory. Here we formulate the fractional counterpart of the Rosenzweig model and analyze the stability behavior of a system. We conclude that there is a threshold for the memory effect parameter beyond which the Rosenzweig model is stable and may be used as a potential agent to resolve PoE from a new perspective via fractional differential equations.     

The occurence of barium in the corneal surface of the barking deer, Muntiacus Muntjak (Zimmerman) as revealed by energy dispersive x-ray micro-analysis

Energy dispersive X-ray micro-analysis with simultaneous visual display by secondary electron emission mode of scanning electron microscopy reveals the occurrence of barium, in addition to silicon, phosphorus, sulphur, potassium and calcium in the corneal surface of the barking deer, Muntiacus muntjak. The lenticular surface on the other hand shows the presence of aluminium silicon, phosphorus and sulphur but no barium.Quantitative data obtained by using the ZAF-4/FLS programme (Link) shows that the relative percentage of barium is the highest of all the elements detected in the cornea, whereas in the lens-surface, sulphur constitutes the maximum percentage.     

Working group report: High energy and collider physics

This is a summary of the projects undertaken by the working group I on high energy and collider physics.     

Anomalous rheology in a nanostructured diblock copolymer/hydrocarbon system and its kinetic origin

Nanostructured squalane solutions (5–20 wt %) of a diblock copolymer, poly(styrene‐b‐hydrogenated isoprene), were prepared by a cosolvent‐casting method. The as‐cast solutions behaved as viscous liquids with terminal flow behavior at room temperature. Upon heating, the solutions gelled, and they did not return to their starting liquidlike state upon cooling. Small‐angle X‐ray scattering (SAXS) revealed a random array of spherical micelles in the as‐cast solutions, which were hypothesized to be in a nonequilibrium state. This abnormal solidification with increasing temperature was correlated with the formation of body‐centered‐cubic (BCC) structures. Isothermal SAXS and rheology measurements also indicated that the rate of formation of BCC structures in the as‐cast solutions increased with temperature. A diffusion‐controlled nucleation‐and‐growth mechanism was proposed for the ordering process in the as‐cast polystyrene‐b‐hydrogenated polyisoprene/squalane solutions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1496–1505, 2004     

Structural and spectroscopic properties of Ru(II) complexes of 4-(aryl)thiosemicarbazones of thiophen-2-carbaldehyde

Six Ru(II) complexes of formula [Ru(L)₂(PPh₃)₂] have been prepared where LH = 4-(aryl)thiosemicarbazones of thiophen-2-carbaldehyde. X-ray crystal structures of five of the complexes are reported. In all the complexes ruthenium is six coordinate with a distorted octahedral cis-P₂, cis-N₂, trans-S₂ donor environment, and each of the two thiosemicarbazone ligands are coordinated in a bidentate fashion forming a four membered chelate ring. The complexes undergo a one-electron oxidation at ～0.5 V vs. Ag/AgCl. The EPR spectrum of the electrochemically oxidized solution at 100 K shows a rhombic signal, with transitions at g₁ = 2.27, g₂ = 2.00 and g₃ = 1.80. DFT calculations on one of the complexes suggest that there is 35% ruthenium and 17% sulfur orbital contribution to the HOMO. These results suggest that the assignment of metal atom oxidation states in these compounds is not unambiguous.     

A Bifunctional Electrocatalyst for Oxygen Evolution and Oxygen Reduction Reactions in Water

Oxygen reduction and water oxidation are two key processes in fuel cell applications. The oxidation of water to dioxygen is a 4 H⁺/4 e^? process, while oxygen can be fully reduced to water by a 4 e^?/4 H⁺ process or partially reduced by fewer electrons to reactive oxygen species such as H₂O₂ and O₂^?. We demonstrate that a novel manganese corrole complex behaves as a bifunctional catalyst for both the electrocatalytic generation of dioxygen as well as the reduction of dioxygen in aqueous media. Furthermore, our combined kinetic, spectroscopic, and electrochemical study of manganese corroles adsorbed on different electrode materials (down to a submolecular level) reveals mechanistic details of the oxygen evolution and reduction processes.