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  • Author or Editor: M. Chacharkar x
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Abstract  

Mobilities of some organic and inorganic ions produced on interaction with -radiations from tritium in air (saturated with water vapor) have been measured. The negative ions generated were allowed to move in the electrical field and collected at the oppositely charged electrode. The mobility of negatively charged ions of air is found to be 2.18 (cm·s–1/V·cm–1), which is in fair agreement with the reported value of 2.2. The calculated mobilities of other ions based on the measured drift time exhibit a variation of up to 6.8 cm s–1·V cm–1. The occurrence of electrophilic sites or repeated presence of more electronegative atoms and or groups in the molecular structure gave higher mobilities. The consideration of parachors, electron affinities and dipole moments of the respective compounds do not reveal any trend.

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Abstract  

The possible determination of tungsten in low grade ores from Northern India, Rajasthan State has been explored by energy dispersive X-ray fluorescence analysis /EDXRF/ technique using radioisotope based excitation of W L X-rays and high resolution Si/Li/ detector system. Finely powdered ore has been diluted with optimal quantity of cellulose and converted into pellets to make it suitable for X-ray analysis after homogenization. The experiments have shown the minimum detectable limit of 33 ppm in diluted matrix. The results are compared with the spectrophotometric stannous chloride-thiocyanate method. EDXRF appears to be encouraging for routine and precise analysis of tungsten in low grade ores.

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Abstract  

Yeast is an important component in microbe based industrial technologies. Due to the techno-economic reasons, the fermentation technique has acquired renewed interest. The effect of -radiation on the fermentation reaction has been investigated. The studies show that exposure of the fermentation mixture to -radiation at 5 kGy enhance alcohol production, whereas irradiation at higher doses, viz., 10 kGy and 25 kGy caused a considerable reduction in the alcohol yield. Therefore, low dose irradiation of fermentation mixtures can be applied for increasing the alcohol production by about 25%.

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Abstract  

Mössbauer spectroscopic studies were carried out on some synthesized iron complexes of Schiff's bases. The studies have evidenced that iron/II/ and iron/III/ species were formed, and no stereoisomers were found. However, the complex of bis/acetylacetone diethylene triamine/ had shown the geometric isomers, and only the Fe/III/ species formed. Immersion of the chelate of iron bis/salicylaldehyde ethylene diamine/ in aerated distilled water for a day had resulted in the conversion of the entire iron/II/ species into the iron/III/ complexes. The exposure to atmosphere had converted a part of iron/II/ into iron/III/ and resulted in distortion of the iron/II/ chelates. This leaves a room to think that oxygen transport or absorption may bring change in the oxidation number of the central metal ion or distortion in the structural arrangements.

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Abstract  

The corrosion of mild steel as a result of interaction with various types of local natural water samples and distilled water is studied with the help of Mössbauer spectroscopy. The data are supplemented with the studies on IR and magnetic properties as and when required. Distilled water and potable water behave in almost similar fashion wherein ferrihydrite and FeOOH are observed to be the precursors of magnetite, the end corrosion product. In case of brakish water, the additional species, viz., FeCl2, FeOOH and an intermediate possibly FeOCl are accounted, and possible mechanisms are suggested.

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Abstract  

Tungsten ores from Degana, Rajashthan State, India are studied using Mössbauer spectroscopy. The low grade ore exhibits two types of mineral assemblages as per chemical states of iron. The relation between ferrous/ferric ratio and tungsten concentration also supports the existence of two types of mineral assemblages. The Mössbauer spectroscopy of concentrate ore samples has shown the absence of iron. The energy dispersive X-ray fluorescence spectroscopy on the contrary has evidenced the presence of iron in concentrate ore samples but at lower concentration on comparison with low grade ores. These differences in behaviour in the above spectroscopic studies may be additionally due to higher attenuation of -radiations and higher atomic weight material in the ore concentrates.

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Abstract  

The corrosion of aluminium has been studied employing the irradiation in situ by neutrons from252Cf and gamma radiations from60Co. The effects of irradiation indicated the absence of pitting, suppression of the corrosion rate, i. e., quantitative reduction in corrosion when measured as weight loss as compared with unirradiated specimens. A protective grayish layer had emerged on the specimen surface which was akin to that formed in simulated experimental conditions carried out in presence of hydrogen peroxide. The possible mechanisms of the elimination of pitting and formation of grayish layer on the surface are discussed.

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