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  • Author or Editor: R. Prasad x
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Abstract  

A complex precursor of composition Cu/Cr=1 has been synthesized, dissolving copper oxalate and ammonium dichromate in aqueous ammonia followed by evaporation and drying. The thermal decomposition of the precursor has been studied in different environments, air/argon. In air, overlapping decomposition of the complex and simultaneous oxidation of the products of decomposition (oxidative decomposition) occur in four steps and the overall process is highly exothermic, whereas the process completes in two stages only in argon preventing oxidation of the products and so resulting negligible heat of decomposition. The elemental analysis and thermogravimetric measurements suggest the stoichiometric formula of the precursor to be CuNH3C2O4NH4CrO4. The precursor is termed as ammoniacal copper oxalate chromate (ACOC). The products of decomposition resulted in different environments have been characterized by X-ray diffraction and particle size analysis. Bi-dispersed particles of CuOCuCr2O4 (Adkins’ catalyst) are obtained in air while mono-dispersed particles of Cu⋅CuCr2O4 (novel Adkins’ catalyst) result in argon environment. The decomposition kinetics of ACOC in argon environment has been found to be zero order and first order for the first and second steps respectively. The values of activation energy corresponding to the first and second step have been found to be 87.63 and 250.36 kJ mol–1, respectively.

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A field experiment was conducted for 2 years at the Indian Agricultural Research Institute, New Delhi to study the effects of duration of variety and nitrogen fertilization on the Ca, Mg and S concentration and uptake in rice. In general, the concentrations of Ca, Mg and S were not significantly influenced by the duration of the rice variety. N fertilization had a tendency to increase the concentration of Ca, Mg and S at 45 days after transplanting as well as at harvest; however, the difference was significant only in the case of the Ca concentration in the grain and only when the N level was raised from 60 to 120 kg N/ha. The duration of the rice variety had a significant effect on the Ca, Mg and S uptake by the straw and grain at harvest, which was higher in the medium duration variety Pusa Basmati-1 than in Pusa Jaldi Dhan-1, mainly due to the higher yields obtained with the former cultivar. Nitrogen application significantly increased the Ca, Mg and S uptake at harvest mainly due to its increasing effects on the grain and straw yields of rice. The average uptake of Ca, Mg and S was 12.6, 13.6 and 3.5 kg per metric ton of grain, respectively.

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Abstract  

The fission track registration technique using Melinex-0 as the detector has been applied to estimate uranium concentration in soil and plant samples collected from different parts of this region of India. The soil samples were powdered and plant samples were ashed to form pellets which were then irradiated with thermal neutrons. Uranium was found to vary from 0.023 to 0.430 ppm in soil samples and 0.026 to 0.216 ppm in plant (Mesophyte group) samples. Fission track technique provides simple, inexpensive, reliable and sensitive method and has high potentiality for uranium analyses in plants and agricultural crops and getting information about underlying ore and mineral deposits.

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A field study conducted for three years (1992–93 to 1994–95) at the Indian Agricultural Research Institute on a sandy clay loam shows that for sustained production in a rice-wheat cropping system integrated nutrient management involving both organic manures/residues and chemical fertilizers is a must. In control plots receiving no organic manures/residues but as high as 120 kg N ha –1 only 8 t ha –1 yr –1 grain could be produced. This productivity could be achieved by Sesbania/cowpea green manuring or mungbean residue or farmyard manure without any chemical fertilizer; with 80 kg N ha –1 it could be increased to 9 t ha –1 yr –1 . Since the availability of farmyard manure is decreasing due to increased mechanization, the generation of in situ organic residues, preferably a legume, is a better alternative.

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Field experiments were conducted for two crop years at the Indian Agricultural Research Institute, New Delhi to study the effect of enriching wheat residue with legume residue on the productivity and nitrogen uptake of a rice-wheat cropping system and soil fertility. The incorporation of wheat residue had an adverse effect on the productivity of the rice-wheat cropping system. When it was incorporated along with Sesbania green manure, not only did its adverse effect disappear but the response to fertilizer N was also increased. There was no response to fertilizer N when Sesbania green manure was incorporated. When wheat residue was incorporated along with Sesbania green manuring, rice responded significantly to fertilizer N up to 120 kg N ha-1 in the first year and to 60 kgN ha-1 in the second year and at these levels of N, Sesbania + wheat residue gave 0.8 to 1.2 t ha-1 more grain, 0.6-1.0 t ha-1 more straw and 8-15 kg ha-1 more N uptake of rice resulting in 0.04-0.17% more organic C, 3-8 kg ha-1 more available P and 17-25 kg ha-1 more available K content in the soil than wheat residue alone at the same rates of N application. The respective increaseas caused by Sesbania green manure + wheat residue over Sesbania green manure alone were 0.3-0.5 t ha-1 in the grain and straw yield, 1-9 kg ha-1 in the N uptake of rice, 0.02-0.10% in organic C, 1-8 kg ha-1 in available P and 35- 70 kg ha-1 in available K content in the soil. These treatments also gave higher residual effects in succeeding wheat than wheat residue alone. The incorporation of residues of both wheat and Sesbania is thus recommended to eliminate the adverse effect of wheat residue and to increase the beneficial effects of Sesbania green manuring.

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Summary Tris(dicarboxylate) complexes of iron(III) with oxalate, maleate, malonate and phthalate viz. K3[Fe(C2O4)3]×3H2O (1), K3[Fe(OOCCH2COO)3]×3H2O (2), K3[Fe(OOCCH=CHCOO)3]×3H2O (3), K3[Fe(OOC-1,2-(C6H4)-COO)3]×3H2O (4) have been synthesized and characterized using a combination of physicochemical techniques. The thermal decomposition behaviour of these complexes have been investigated under dynamic air atmosphere upto 800 K. All these complexes undergo a three-step dehydration/decomposition process for which the kinetic parameters have been calculated using Freeman-Carrol model as well as using different mechanistic models of the solid-state reactions. The trisoxalato and trismalonato ferrate(III) complexes undergo rapid dehydration at lower temperature below 470 K. At moderately higher temperatures (i.e. >600 and 500 K, respectively) they formed bis chelate iron(III) complexes. The trismalonato and trismaleato complexes dehydrate with almost equal ease but the latter is much less stable to decomposition and yields FeCO3 below 760 K. The cis-dicarboxylate complexes particularly with maleate(2-) and phthalate(2-) ligands are highly prone to the loss of cyclic anhydrides at moderately raised temperatures. The thermal decomposition of the tris(dicarboxylato)iron(II) to iron oxide was not observed in the investigated temperature range up to 800 K. The dehydration processes generally followed the first or second order mechanism while the third decomposition steps followed either three-dimensional diffusion or contracting volume mechanism.

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A field study conducted for two years at the Indian Agricultural Research Institute, New Delhi showed that intercropping potato with fenugreek is highly profitable and provides some in-season income to the potato growers. It also serves as an insurance against complete loss of income when the potato prices crash in the market.

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Abstract  

The sensitive and simple fission track detection technique using a dry method with Melinex-0 plastic track detector has been applied for the determination of uranium concentration in samples of domestic water supply plants collected from different states of India, namely West Bengal, Uttar Pradesh, Rajasthan, Punjab and Delhi. Our analyses show that uranium concentration of water samples collected from different types of domestic water supply plants vary from 0.6±0.02 to 19.2±0.6 g/l. The present investigations may be useful from the point of view of radiation hygiene.

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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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Field experiments were carried out for 3 years to assess the efficacy of organic manures (Sesbania, Leucaena, cowpea, mungbean, wheat straw and FYM) in enhancing the productivity of rice and in supplying Fe. Green manuring with Sesbania gave the highest rice yield, whereas the lowest yield was recorded with wheat straw incorporation. The concentration and uptake of Fe by rice was significantly higher with organic manures. The Fe status of the soil after 3 crops of rice declined from the initial value, but the decline was least with FYM, followed by green manures. The application of organic manures is a good source for a sustained supply of Fe in soil.

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