Dating of hot springs at Attri,Tarabalo and Athmalik sites in Odisha,India using radiocarbon technique

Journal of Radioanalytical and Nuclear Chemistry - In this study environmental radioisotopes of water (3H and 14C) were used to determine the residence time of thermal waters. The temperature of...     

Ferromagnetism Exhibited by Nanoparticles of Noble Metals

Gold nanoparticles with average diameters in the range 2.5–15 nm, prepared at the organic/aqueous interface by using tetrakis(hydroxymethyl)phosphonium chloride (THPC) as reducing agent, exhibit ferromagnetism whereby the saturation magnetization M_S increases with decreasing diameter and varies linearly with the fraction of surface atoms. The value of M_S is higher when the particles are present as a film instead of as a sol. Capping with strongly interacting ligands such as alkane thiols results in a higher M_S value, which varies with the strength of the metal–sulfur bond. Ferromagnetism is also found in Pt and Ag nanoparticles prepared as sols, and the M_S values vary as Pt>Au>Ag. A careful study of the temperature variation of the magnetization of Au nanoparticles, along with certain other observations, suggests that small bare nanoparticles of noble metals could indeed possess ferromagnetism, albeit weak, which is accentuated in the presence of capping agents, specially alkane thiols which form strong metal–sulfur bonds.     

Energy landscape, antiplasticization, and polydispersity induced crossover of heterogeneity in supercooled polydisperse liquids

Polydispersity is found to have a significant effect on the potential energy landscape; the average inherent structure energy decreases with polydispersity. Increasing polydispersity at a fixed volume fraction decreases the glass transition temperature and the fragility of glass formation analogous to the antiplasticization seen in some polymeric melts. An interesting temperature dependent crossover of heterogeneity with polydispersity is observed at low temperature due to the faster buildup of dynamic heterogeneity at lower polydispersity.     

Simulation of PD patterns due to a narrow void in different E-field distribution

For simulation of Partial Discharge (PD) patterns, a Finite Difference Method (FDM) based model is put forward, in which three significant PD parameters are incorporated, viz. the critical field intensity for partial discharge occurrence E_c, residual field intensity E_r and locations of voids inside the dielectric. The void taken in this simulation is a narrow rectangular parallelepiped, i.e. the length and breadth of the void (in the direction normal to the field) is less compared to the height (in the direction of the field) of the void. In this paper, three different electrode systems are considered, viz. Plane–Plane, Point–Plane and Point–Point. The supply voltage is considered to be sinusoidal in nature. PD simulations for different locations of voids inside the dielectric for these three configurations are carried out considering occurrence of PD and residual field to be stochastic in nature for a constant E_c. The inception and extinction of PD, effect of applied voltage on PD, shape of PD patterns in relation to instantaneous released charge amplitude, and the amount of charge which is released due to PDs during a course of time, are studied and reported in this paper.     

Light-matter interactions via the exact factorization approach

The exact factorization approach, originally developed for electron-nuclear dynamics, is extended to light-matter interactions within the dipole approximation. This allows for a Schrödinger equation for the photonic wavefunction, in which the potential contains exactly the effects on the photon field of its coupling to matter. We illustrate the formalism and potential for a two-level system representing the matter, coupled to an infinite number of photon modes in the Wigner-Weisskopf approximation, as well as to a single mode with various coupling strengths. Significant differences are found with the potential used in conventional approaches, especially for strong couplings. We discuss how our exact factorization approach for light-matter interactions can be used as a guideline to develop semiclassical trajectory methods for efficient simulations of light-matter dynamics.