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  • Author or Editor: H. Randhawa x
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Abstract  

The thermolysis of potassium hexa(carboxylato)ferrate(III) precursors, K3[Fe(L)6xH2O (L=formate, acetate, propionate, butyrate), has been carried out in flowing air atmosphere from ambient temperature to 900°C. Various physico-chemical techniques i.e. TG, DTG, DTA, XRD, IR, Mössbauer spectroscopy etc. have been employed to characterize the intermediates and end products. After dehydration, the anhydrous complexes undergo exothermic decomposition to yield various intermediates i.e. potassium carbonate/acetate/propionate/butyrate and α-Fe2O3. A subsequent decomposition of these intermediates leads to the formation of potassium ferrite (KFeO2) above 700°C. The same ferrite has also been prepared by the combustion method at a comparatively lower temperature (600°C) and in less time than that of conventional ceramic method.

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Abstract  

The thermal decomposition of lithium hexa(carboxylato)ferrate(III) precursors, (Li3[Fe(L)6xH2O, L = formate, acetate, propionate, butyrate), has been carried out in flowing air atmosphere from ambient temperature upto 500 °C. Various physico-chemical techniques, i.e., TG, DTG, DTA, XRD, SEM, IR, Mössbauer spectroscopy, etc., have been employed to characterize the intermediates and end products. After dehydration, the anhydrous complexes undergo decomposition to yield various intermediates, i.e., lithium oxalate/acetate/propionate/butyrate, ferrous oxalate/acetate and α-Fe2O3 in the temperature range of 185–240 °C. A subsequent decomposition of these intermediates leads to the formation of nanosized lithium ferrite (LiFeO2). Ferrites have been obtained at much lower temperature (255–310 °C) as compared to conventional ceramic method. The same nano-ferrite has also been prepared by the combustion method at a comparatively lower temperature (400 °C) and in less time than that of conventional ceramic method.

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Abstract  

The mechanism of thermal decomposition of the metal complexes of sulphamethoxazole (SMZ) viz: [Ag(SMZ)H2O], [Cd(SMZ)2(H2O)2], [VO(SMZ)2(H2O)2], [UO2(SMZ)2]H 2O, [Hg(SMZ)2(H2O)2] and [Co(SMZ)2(H2O)2]H2O has been accomplished on the basis of TG, DTG and DTA studies. The mechanism of thermal decomposition of these complexes conforms to the stoichiometry of the complexes based on elemental analysis.

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The heats of formation forπ-π * charge transfer interactions have been computed from the charge transfer spectra of molecular complexes formed between methylbenzene donors andπ-electron acceptors.

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The thermal decomposition of iron(III) citrate pentahydrate, Fe(C6H5O7) · 5 H2O, has been investigated at different temperatures in air using Mössbauer spectroscopy, nonisothermal techniques (DTA-TG) and X-ray diffraction. The reduction of iron(III) to iron(II) takes place at 553 K. At higher temperature the formation of α-Fe2O3 and γ-Fe2O3 as the ultimate thermal decomposition products has been confirmed.

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Iron and zinc deficiency affects more than half of the world population due to low inherent micronutrient content of cereals and other staple foods. The micronutrient deficiency is further aggravated by poor availability of these minerals in calcareous soils and their uptake by crop plants. Series of available wheat-Aegilops addition lines were evaluated for identification of alien chromosomes carrying genes for high grain iron and zinc concentrations and release of mugineic acid(s) facilitating micronutrient uptake under their deficient conditions. Addition lines of chromosome 2Sv, 2Uv and 7Uv of Ae. peregrina, 2Sl and 7Sl of Ae. longissima and 2U of Ae. umbellulata were found to carry genes for high grain iron whereas the group 7 chromosomes had genes for higher grain zinc. Higher release of mugineic acid (MA) under iron deficient condition was observed in addition lines of chromosome 2Sv, 2Uv, 4Uv and 7Sv of Ae. peregrina, 2Sl and 6Sl of Ae. longissima and 2U and 5U of Ae. umbellulata. Higher grain and root iron concentration and MA(s) release under iron sufficient condition in the group 2 chromosome addition lines suggests that their high grain iron may be attributed to the higher uptake of the micronutrients through MA(s). These addition lines with two- to threefold high grain iron and zinc concentration could be used for precise introgression of genes into elite wheat cultivars for enhanced uptake of these micronutrients by wheat plants in problematic soils and their biofortification in grains.

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