Archives-December 2012

A new heteropolyacid-based cation exchanger [Bismuth(III) tungstomolybdate (BTM)] has been synthesized and characterized using chemical stability, pH titration, distribution studies, thermal stability, FTIR, X-Ray analysis and TGA curve analysis. It exhibits 1.05 meq/g ion exchange capacity for sodium ions. The chemical stability of the material has been tested in acidic, neutral and basic media. Its distribution behaviour for nine metal ions has been studied. Ion exchanger column was used for binary separation and hardness causing metal ions removal.

Array patterns depends on type of elements, spacing between the elements and length of the array etc., conventionally elements are spaced at ?/2 in an array. However, in this paper we are made to generate the normalized radiation patterns for different spacing and different types of elements. It has been possible to control the radiation pattern by controlling the spacing between the elements. The arrays considered contain non-identical elements with non-uniform spacing. The results are useful for design of arrays to produce low side lobes for EMI suppression.

Oxidative stress is one of the most popular terms in biomedicine. Oxidative Stress is a general term used to describe the steady state level of oxidative damage in a cell, tissue, or organ, results from an imbalance between radical-generating and radical scavenging systems, i.e. increased free radical production or reduced activity of antioxidant defenses or both. A great number of aromatic, medicinal, spice and other plants contain chemical compounds exhibiting antioxidant properties. In the present study the antioxidant activity and radical scavenging activity of aqueous and alcoholic extracts of Allium sativum Linn. traditionally used by Indian population as folk remedies was evaluated.

Grievances or conflicts are part of industrial/ corporate scenario. In the working lives, employees occasionally have reasons to be uncomfortable, disappointed or aggrieved either about certain managerial decisions and practices or service conditions. The question then is whether this particular symptom or feeling is given any attention or is ignored altogether. What are the pros and cons of each of the approaches? The conflicts or disappointments cannot be eliminated but their expressions will contribute towards their reduction. Such expressions lead to adjustments and further improved organizational effectiveness. To a large extent, the approach to the problem will be governed by several variables such as the style of management, size of the enterprise, level of education of the workforce, technology of the plant and the extent of unionization of the work force.

The Discrete Tchebichef Transform (DTT) based on orthogonal Tchebichef polynomials can be an alternative to Discrete Cosine Transform (DCT) for JPEG image compression standard. The properties of DTT are not only very similar to DCT; it has also higher energy compactness and lower computational advantage using a set of recurrence relation. In this, DTT is coupled with Set partitioning in hierarchical coding techniques (SPIHT).It has been demonstrated that, DTT requires lesser number of bits to encode the coefficients than DCT for a given compression ratio. We present SPIHT which provides better performance than EZW .Later median filter is added in order to increase the PSNR and improve the quality the taken input image.

Antioxidant activity of petroleum ether, benzene, ethyl acetate, methanol and ethanol extracts of the root of mangrove herb Suaeda monaica have been tested using various antioxidant model system viz, DPPH, hydroxyl, superoxide, ABTS and reducing power. Methanol extract of Suaeda monaica is found to possess higher DPPH and hydroxyl radical scavenging activity. Ethanol and methanol extracts of Suaeda monaica exhibited highest superoxide and ABTS radical cation scavenging activity. Methanol extract of root of Suaeda monaica showed the highest reducing ability. This study indicates significant free radical scavenging potential of Suaeda monaica root which can be exploited for the treatment of various free radical mediated ailments.

The kinetics of nickel leaching from lateritic Chromite overburden (COB) by organic (Oxalic) acid has been investigated. In this context, the effects of oxalic acid concentration and temperature upon the rate of nickel extraction from COB were evaluated. The leaching kinetics study was also performed for nickel extraction from thermally pre-treated COB, since nickel extraction was improved by the thermal pre-treatment of the COB. Well established shrinking core models were applied to study the kinetics of nickel extraction from raw and pre-treated COB. The experimental outcomes evident that, rates of nickel extraction from raw as well as the pre-treated COB were controlled by diffusion controlled shrinking core rate kinetics model. Further, apparent activation energies for extraction of nickel from raw and pre-treated COB were estimated to be 14.31 kJ/mol and 14.56 kJ/mol respectively.

Nitrate and nitrite are naturally occurring ions that are ubiquitous in the environment. Both are products of the oxidation of nitrogen ( which comprises roughly 78% of the atmosphere) by micro-organisms in plants, soil or water and to a lesser extent by electrical discharges such as lightening. After a period of time, the nitrates seep into the water table. This is a concern primarily for those whose household water source is a well rather than their city. Nitrates can cause cancer in humans, when consumed over a period of time. The objective of this study is investigation and determination of nitrate, nitrite and other physico-chemical parameters of Southern Bijapur district. 30 samples of water were analysed for pH, TGS, Total hardness, alkalinity, nitrate and nitrites. The southern part of Bijapur district had more than the maximum acceptable concentration (MAC) for nitrate in drinking water. It was concluded that nitrate contents in drinking water was found to be 8.0 to 392 mg/L.

Seeds of Vigna aconitifolia Jacq. (mataki seeds) pre-soaked in cell free culture filtrate of post-harvest sapota fungi viz. Geotrichum candidum, Aspergillus niger and Rhizoctonia solani. In order to study the effect of incubation period on toxin production, the fungi were grown for different period ranging from 5-25 days. It is clear from the result that with the increase in incubation period, toxicity also increased. All the fungal filtrates showed decrease in percentage of seed germination with increase in filtrate age i.e. soaking time in all the fungal filtrates.

Thin films of tin disulphide on glass substrates were prepared by spray pyrolysis technique using precursor solutions of SnCl2.2H2O (0.04 M) and n-n dimethyl thiourea (0.02 M - 0.12 M) at different precursor concentration ratios varied in the range 1:0.5 – 1:3, keeping other deposition parameters are constant. The films are found to be n type electrical conduction using hot probe technique. X ray diffraction analysis revealed the polycrystalline nature of tin disulphide thin film with hexagonal structure and a preferential orientation along (002) plane. The size of the tin disulphide crystallites was determined using the Full Width at Half Maximum values of Bragg peaks. The surface morphology had been observed on the surface of these films using scanning electron microscope. The optical absorption and transmittance have been recorded for the films in the wavelength range 400 - 800 nm. From the analysis of the absorption region data both allowed and forbidden optical transition nature was determined for the films in the above wavelength range. The electrical resistivity values in dark and light were determined with respect to the precursor concentration ratio.