Acoustical-Mode-Driven Electron-Phonon Coupling in Transition-Metal Diborides

We show that the electron-phonon coupling in the transition-metal diborides NbB2 and TaB2 is dominated by the longitudinal acoustical (LA) mode, in contrast to the optical E_{2g} mode dominated coupling in MgB2. Our ab initio results, described in terms of phonon dispersion, linewidth, and partial electron-phonon coupling along Gamma to A, also show that (i) NbB2 and TaB2 have a relatively weak electron-phonon coupling, (ii) the E_{2g} linewidth is an order of magnitude larger in MgB2 than in NbB2 or TaB2, (iii) the E_{2g} frequency in NbB2 and TaB2 is considerably higher than in MgB2, and (iv) the LA frequency at A for TaB2 is almost half of that of MgB2 or NbB2.Comment: 4 pages, 4 figures, and 1 tabl

Macro and microscopic characters of Maerua oblongifolia (Forssk.) A. Rich leaf

The paper deals with a detailed investigation on the leaves of Maerua oblongifolia (Forssk.) A. Rich. which includes it’s morphological, anatomical and powder analysis. It is a low woody bushy under-shrub belonging to the family Capparaceae. The leaves are used in treatment of as fever, ear ache, stomach ache, skin infections, urinary calculii, diabetes mellitus, epilepsy, rigidity in lower limbs, and abdominal colic. The leaf amphistomatic, with mostly anamocytic, few tetracytic stomata. In transverse section of leaf is ribbed on either sides at midvein, epidermis one layered. Mesophyll differentiated into palisade and spongy tissues. Ground tissue of midvein differentiated into palisade, collenchyma and parenchyma. The midvien consists of one large oval shaped vascular bundles arranged are at the centre. Petiole in transverse section is circular adaxially small, grooved at centre and epidermis is having one layered, a single circular vascular bundle present at the centre, vascular bundle is enclosed by endodermis. The powder microscopic and organoleptic characters are also presented in this study. This study would helps as an appropriate source for authentification of the present studied drug. &nbsp

Violation of Bell's inequality for phase singular beams

We have considered optical beams with phase singularity and experimentally verified that these beams, although being classical, have properties of two mode entanglement in quantum states. We have observed the violation of Bell's inequality for continuous variables using the Wigner distribution function (WDF) proposed by Chowdhury et al. [Phys. Rev. A \textbf{88}, 013830 (2013)]. Our experiment establishes a new form of Bell's inequality in terms of the WDF which can be used for classical as well as quantum systems.Comment: 7 pages, 9 figures and 1 tabl

Studies on ammoniacal leaching of copper oxide minerals

Aqueous ammoniacal leaching of an oxidized copper ore from the mines of M/s Hindustan Copper Limited : Malanjkhand are reported. Factors which influence copper recovery such as ammonia concentration, solid-liquid ratio, particle size and agitation have been studied at ambient temperature. Over 90% copper extraction could be achieved at 1.5 mo1ar concentration of ammonia, 10% solids and at a stirring speed of 550 Min- . A kinetic study of the process indicated a mixed control reaction mechanism. The copper ammine solution obtained in the leaching step was subjected to precipitation by stripping of the ammonia at different temperatures and air flow rates. The kinetic treatment of the data obtained on preci[litation process revealed that the decomposition reaction is controlled by chemical reaction control. The precipitated product analysed 75% Cu with a recovery of 80-85% copper

Studies on the beneficiation of copper oxide minerals

Bench scale experiments on the beneficiation of copper oxides were conducted using different chelating agents, viz. Cupferron, 8-Hydroxyquinoline, a-Benzoin oxime and sodiumdiethyldithiocarbamate. Among the four collectors tried, diethyldithiocarbamate was found to be effective in achieving good recovery and grade. Also the consumption of the reagent was less compared to other collectors. All the collectors have exhibited excellent selectivity towards copper and fairly good concentrate was obtained. Adsorption studies revealed that the adsorption of the collector on the mineral surface follows a true chemical reaction. Investigation on the nature of complexation with diethyldithiocarbamate has indicated that each copper atom on the surface will be complexed with two diethyldithiocarbamate molecules. Variables like reagent concentration, pH of the pulp, impeller speed, etc. were studied

Beneficiation of Low Grade Ores by Electro-Column Flotation Technique.

Three types of flotation columns were developed with a column dia of 8.0 cm and a length of 160 cm. The first type consists of an ordinary column fitted with a porous plate at the bottom. The second type consists of two electrodes at the bottom to obtain very fine and uniform bubbles generated electrolytically and the third is a combination of first and second types, i.e. to get both electrolytic bubbles and air from the compressor through porous plate. Three different ores were tested-gold tailings for recovery of scheelite, copper tailings (chalcopyrite) and oxide copper ore. In the case of scheelite and copper oxides, good results were obtained with the first type of column itself, whereas the third type column was found fairly effective in the recovery of chalcopyrite. The variables like the effect of reagent concentration, column height above the feed point, feed flow ra te, current density, air flow rate, particle size were examined

Separation of minerals by electroflotation

Bench scale experiments were conducted to study the separation of chalcopyrite fines. Three different electroflotation cells were designed and beneficiation response of chalcopyrite was investigated.Electrolytic oxygen bubbles were found to have significant influence on the beneficiation of chalcoyrite.High enrichment ratio of chalcopyrite was observed by column cum electroflotation method using diethyldithiocarbamate as collector