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The thermal decomposition in air of iron(II) sulphate heptahydrate in the presence of calcium, strontium and barium carbonates has been carried out. The decomposition path varies from carbonate to carbonate. Also, these decompositions are different from those of basic beryllium carbonate and basic magnesium carbonate. The results obtained for the kinetics of thermal decomposition have also been presented.

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The kinetics of thermal decomposition of iron(II) sulphate hexa- to monohydrates, as well as the hydroxy- and oxysulphates of iron(III), are presented and discussed. The results confirm that the final intermediate that decomposes to iron(III) oxide and sulphur trioxide during the thermal decomposition of any hydrate of iron(II) sulphate is the oxysulphate, Fe2O(SO4)2.

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Activation energies for the thermal decomposition reactions of hydrates and basic salts of FeSO4 were calculated using both conventional and statistical methods. The advantage and disadvantage of both methods is brought out. A combined method is proposed.

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Thermal analysis of iron(II) sulphate heptahydrate in air. V

Thermal decomposition of hydroxy and oxysulphates

Journal of Thermal Analysis and Calorimetry
Authors: M. Swamy and T. Prasad
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Series of basic sulphates which were precipitated by the hydrolysis of Fe(OH)SO4 in the presence and absence of metallic iron were studied from compositional, crystallographic and thermal decomposition points of view. The results are presented and discussed. It was found that high pure iron oxides as well as high grade red iron oxide pigments can be obtained by agitating the basic sulphates in hot ammonical medium followed by roasting. Commercial exploitation of the results is suggested.

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In this study, we describe the membrane lipid composition of eight clinical isolates (azole resistant and sensitive strains) of Candida albicans isolated from AIDS/ HIV patients. Interestingly, fluorescence polarization measurements of the clinical isolates displayed enhanced membrane fluidity in fluconazole resistant strains as compared to the sensitive ones. The increase in fluidity was reflected in the change of membrane order, which was considerably decreased (decrease in fluorescence polarization “p” value denotes higher membrane fluidity) in the resistant strains. The ergosterol content in azole susceptible isolates was greater, almost twice as compared to the resistant isolates. However, no significant alteration was observed in phospholipid and fatty acid composition of these isolates. Labeling experiments with fluorescamine dye revealed that the percentage of phosphatidylethanolamine exposed to the membrane’s outer leaflet was higher in the resistant strains as compared to the sensitive strains, indicating increased floppase activity of the two major ABC drug efflux pumps, CDR1 and CDR2 possibly due to their overexpression in resistant strains. The results of the present study suggest that changes in the status of membrane lipid phase especially the ergosterol content and increased activity of drug efflux pumps by overexpression of ABC transporters, CDR1 and CDR2 might contribute to fluconazole resistance in C. albicans isolated from AIDS/HIV patients.

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Thermal analysis of iron(II) sulphate heptahydrate in air

III. Thermal decomposition of intermediate hydrates

Journal of Thermal Analysis and Calorimetry
Authors: M. S. R. Swami and T. P. Prasad

Iron(II) sulphate hydrates (hexa- through mono-) have been prepared and their thermal decomposition behaviours have been studied in air by isothermal and dynamic thermal analysis methods. The results show that their behaviours are similar to that of the heptahydrate. The stepwise loss of water molecules is accompanied by oxidation. Under a restricted supply of oxygen, the anhydrous sulphate is oxidized directly to Fe2O(SO4)2 without the formation of Fe(OH)SO4. When free exchange with oxygen is allowed, Fe(OH)SO4 is formed, which in turn decomposes to Fe2O(SO4)2. The decomposition of Fe2(SO4)2 to iron(III) oxide and sulphur oxides appears to occur via two independent paths — one direct and other through iron(III) sulphate.

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