Utilization of ferro-manganese slag for production of manganese sulphate and Electrolytic manganese metal/manganese di-oxide

High and low ferro-manganese slags have been studied for production of manganese sulphate which forms the intermediate product for production of electrolytic manganese metall-di-oxide. With low manganese slag, a recovery of 72% manganese is obtained with 100% excess acid in the spent liquor over the stoichiometric equi-valent to contained manganese in the slag with the granulated slag ground to - 100 mesh. This recovery increases to 80% when the slag is ground to —200 mesh. With high manganese slag, a recovery of 86% is obtained with 37% excess acid. This recovery increases to 95% with excess acid, but aluminium and silicon going into the leached solution increases more than double fold. The leached purified manganese sulphate solution is found quite suitable for product Ton of EMM/EMD/CMD

Crushing and Grinding of Electrodeposited Manganese Dioxide

Electrolytic manganese dioxide, for use as an efficient depolarizer in dry cells, is produced by the electrolysis of a solution of manganese sulphate and sulphuric acid at a temperature of 95°C. As the electrolysis proceeds, manganese dioxide is deposited in thick adherent form on the anodes. The anodes are taken out when the deposited manganese dioxide attains a thickness of 15-25 mm in about 10-15 days on continuous operation. The thickness of the EMD deposited on the anode depends on the current density and the duration of electrolysis. The anodes after taking out of the electrolytic cells are washed thoroughly with water to remove the carried over electrolyte and hot air dried. The sudden fluctuation in temperature, on lifting the anodes from the hot electrolytic cell and washing, cracks the EMD deposit. After drying, the deposits are easily stripped from the anodes by mild striking

Bose-Fermi mixtures in an optical lattice

We study an atomic Bose-Fermi mixture with unpolarized fermions in an optical lattice. We obtain the Mott ground states of such a system in the limit of the deep optical lattice and discuss the effect of quantum fluctuations on these states. We also study the superfluid-insulator transitions of bosons and metal-insulator transition of fermions in such a mixture within a slave-rotor mean-field approximation, and obtain the corresponding phase diagram. We discuss experimental implications of our results

A model for correlations in stock markets

We propose a group model for correlations in stock markets. In the group model the markets are composed of several groups, within which the stock price fluctuations are correlated. The spectral properties of empirical correlation matrices reported in [Phys. Rev. Lett. {\bf 83}, 1467 (1999); Phys. Rev. Lett. {\bf 83}, 1471 (1999.)] are well understood from the model. It provides the connection between the spectral properties of the empirical correlation matrix and the structure of correlations in stock markets.Comment: two pages including one EPS file for a figur

The role of electron-electron interactions in two-dimensional Dirac fermions

The role of electron-electron interactions on two-dimensional Dirac fermions remains enigmatic. Using a combination of nonperturbative numerical and analytical techniques that incorporate both the contact and long-range parts of the Coulomb interaction, we identify the two previously discussed regimes: a Gross-Neveu transition to a strongly correlated Mott insulator, and a semi-metallic state with a logarithmically diverging Fermi velocity accurately described by the random phase approximation. Most interestingly, experimental realizations of Dirac fermions span the crossover between these two regimes providing the physical mechanism that masks this velocity divergence. We explain several long-standing mysteries including why the observed Fermi velocity in graphene is consistently about 20 percent larger than the best values calculated using ab initio and why graphene on different substrates show different behavior.Comment: 11 pages, 4 figure

Interaction driven metal-insulator transition in strained graphene

The question of whether electron-electron interactions can drive a metal to insulator transition in graphene under realistic experimental conditions is addressed. Using three representative methods to calculate the effective long-range Coulomb interaction between $\pi$-electrons in graphene and solving for the ground state using quantum Monte Carlo methods, we argue that without strain, graphene remains metallic and changing the substrate from SiO$_2$ to suspended samples hardly makes any difference. In contrast, applying a rather large -- but experimentally realistic -- uniform and isotropic strain of about $15\%$ seems to be a promising route to making graphene an antiferromagnetic Mott insulator.Comment: Updated version: 6 pages, 3 figure

Portability of tag SNPs across isolated population groups: an example from India

Isolated population groups are useful in conducting association studies of complex diseases to avoid various pitfalls, including those arising from population stratification. Since DNA resequencing is expensive, it is recommended that genotyping be carried out at tagSNP (tSNP) loci. For this, tSNPs identified in one isolated population need to be used in another. Unless tSNPs are highly portable across populations this strategy may result in loss of information in association studies. We examined the issue of tSNP portability by sampling individuals from 10 isolated ethnic groups from India. We generated DNA resequencing data pertaining to 3 genomic regions and identified tSNPs in each population. We defined an index of tSNP portability and showed that portability is low across isolated Indian ethnic groups. The extent of portability did not significantly correlate with genetic similarity among the populations studied here. We also analyzed our data with sequence data from individuals of African and European descent. Our results indicated that it may be necessary to carry out resequencing in a small number of individuals to discover SNPs and identify tSNPs in the specific isolated population in which a disease association study is to be conducted