Dielectric properties of Li2O-3B2O3 glasses

The frequency and temperature dependence of the dielectric constant and the electrical conductivity of the transparent glasses in the composition Li2O-3B2O3 (LBO) were investigated in the 100 Hz- 10 MHz frequency range. The dielectric constant and the loss in the low frequency regime were electrode material dependent. Dielectric and electrical relaxations were respectively analyzed using the Cole-Cole and electric modulus formalisms. The dielectric relaxation mechanism was discussed in the framework of electrode and charge carrier (hopping of the ions) related polarization using generalized Cole-Cole expression. The frequency dependent electrical conductivity was rationalized using Jonscher's power law. The activation energy associated with the dc conductivity was 0.80 \pm 0.02 eV, which was ascribed to the motion of Li+ ions in the glass matrix. The activation energy associated with dielectric relaxation was almost equal to that of the dc conductivity, indicating that the same species took part in both the processes. Temperature dependent behavior of the frequency exponent (n) suggested that the correlated barrier hopping model was the most apposite to rationalize the electrical transport phenomenon in Li2O-3B2O3 glasses. These glasses on heating at 933 K/10h resulted in the known non-linear optical phase LiB3O5.Comment: 32 pages, 13 figure

Reference curves for a fitness battery developed for children ages 5-12 years in England

Purpose: Reference curves have already been created for a variety of different physical testing batteries across a number of countries. Due to results differing between countries for the same sex and age, it is important that reference curves are created specific for each country. Therefore, the aim of this study was to provide reference curves for five different fitness tests that assess the core components of health related fitness within children in England. Method: Following institutional ethics approval, parental informed consent and child assent was obtained for a total of 39,199 children aged between 5 and 12 years completed tests for explosive power, agility, hand eye coordination, lower body strength and upper body strength. To calculate reference values Generalised Additive Models for Location, Scale and Shape (GAMLSS) were used. Results: Reference curves and centiles show differences in performance levels of the fitness tests between sex and age groups. These reference curves and centiles provide age and sex comparisons to enable progress monitoring of children's physical fitness competence within England and comparisons to other countries. Conclusion: Girls are outperformed from a young age group and both upper and lower body strength decreases are seen at ages nine and ten. In physical activity and health related fitness interventions, both girls and boys in Key stage two should be targeted to maintain progression and lessen the gender divide

Environmental Management for Sustainable Growth in an Integrated Iron and Steel Plant

The manufacture of steel involves a large number of processing which lead to complex problems of environme-ntal pollution. Coke making and sintering are two of the major areas in so far as pollution is concerned. Slag constitutes the major portion of solid wastes. Waste generation adversely affects productivity and contributes to the high cost of production. It has been shown that improving the efficiency of operation and fuel saving measures help in reducing pollution in steel plants. Utilization of slag, mill scale, sludge and dusts, safe disposal of hazardous wastes and minimization of emissions of CO, C02, 502, NOx, cyanides, volatile organic compounds (VOC), NH3, suspended particulate matters (SPM) etc, are essential steps towards environmental management

Historical perspective of iron in ancient India

Iron is an important metal which has influenced the march of civilization over atleast 5000 years and it has been in the service of man from the dawn of time. The ancient scriptures and legends have extensive references about the use of iron. The archaeological evidences show that iron was being made all over India and there was no written records of the process of manufacturing iron. The technology has been handed over from one person to another within a limited group. Unfortunately this art phased out with the development of new technology during 19-20 century. The paper discusses the various sources of existence of iron, its utilization and importance right from pre-Rig Vedic period upto the first half of 20 century

Electroslag remelting - Its status, mechanism and refining aspects in the production of quality steels

Electroslag remelting has been established as a new measure for the production of quality steels. Many properties of ESR steels are dramatically superior to those of conventionally produced steels. Majority of inclusions are eliminated during ESR depending on slag composition, temperature and melt rate. Usually, after ESR, the metal does not contain sany inclusion larger than 10-12 mm. The pronounced effect of ESR is a feasible and effective method of further enhancing the ductility and charpy U-notch toughness, with some improvement in strength as a result of refinement. ESR is a convenient and economic route for processing steels and alloys which are otherwise difficult to process

A Comprehensive pollution control system for the mitigation of fine particulates of lead and Sox gases from secondary lead smelters

A large number of small scale units making use of scrap, dross and junk automobile storage batteries do not adopt appropriate pollution control measures mostly due to their financial constraints. They emit fine par¬ticulates of lead and SO, gases to the surrounding atmosphere which are injurious to the health of people residing in the neighbouring localities. In view of this, National Metallurgical Laboratory, Jamshedpur has de¬veloped a comprehensive pollution control system for control of fine par¬ticulates of lead and SOX gases from secondary lead smelters

Magnetite ore of nagaland—its mineralogy and reduction kinetics

The magnetite body near Pokphur in the Kiphere district of Nagaland is geologically quite different and a rare type of occurrence associated with ophiolite. Mineralogical studies reveal the presence of magnetite, chromite and hematite followed by goethite, ilmentite, trevorite, pentlandite and millerrite. Magnetite grains are weathered to various degrees and sometimes fractured. Reduction studies indicate that in gas-solid system considerable reduction of magnetite ore takes place in initial 60 minutes, further the rate of reduction becomes slow. In gas-solid system the percentage reduction of magnetite ore is considerably more compared to solid-solid systems

Utilisation of waste battery scrap

The waste battery scrap can be metallurgically treated to separate lead from various impurities such as sulphates, oxides and other metals in scrap. An attempt has been made to smelt the treated battery scrap for recovery of lead as well as for SO= pollution abatement

Significance of Four Methionine Sulfoxide Reductases in Staphylococcus aureus

Staphylococcus aureus is a major human pathogen and emergence of antibiotic resistance in clinical staphylococcal isolates raises concerns about our ability to control these infections. Cell wall-active antibiotics cause elevated synthesis of methionine sulfoxide reductases (Msrs: MsrA1 and MsrB) in S. aureus. MsrA and MsrB enzymes reduce S-epimers and R-epimers of methionine sulfoxide, respectively, that are generated under oxidative stress. In the S. aureus chromosome, there are three msrA genes (msrA1, msrA2 and msrA3) and one msrB gene. To understand the precise physiological roles of Msr proteins in S. aureus, mutations in msrA1, msrA2 and msrA3 and msrB genes were created by site-directed mutagenesis. These mutants were combined to create a triple msrA (msrA1, msrA2 and msrA3) and a quadruple msrAB (msrA1, msrA2, msrA3, msrB) mutant. These mutants were used to determine the roles of Msr proteins in staphylococcal growth, antibiotic resistance, adherence to human lung epithelial cells, pigment production, and survival in mice relative to the wild-type strains. MsrA1-deficient strains were sensitive to oxidative stress conditions, less pigmented and less adherent to human lung epithelial cells, and showed reduced survival in mouse tissues. In contrast, MsrB-deficient strains were resistant to oxidants and were highly pigmented. Lack of MsrA2 and MsrA3 caused no apparent growth defect in S. aureus. In complementation experiments with the triple and quadruple mutants, it was MsrA1 and not MsrB that was determined to be critical for adherence and phagocytic resistance of S. aureus. Overall, the data suggests that MsrA1 may be an important virulence factor and MsrB probably plays a balancing act to counter the effect of MsrA1 in S. aureus.This work was supported in part by a Warner/Fermaturo grant and A.T. Still University Board of Trustees Research Funds, by grant 1R15AI090680-01 from the National Institutes of Health to VKS, and grants from the Kirksville College of Osteopathic Medicine Biomedical Sciences Graduate Program to TRJ and KRB. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript