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Abstract  

Gamma-ray induced decomposition of binary mixtures of potassium nitrate with 90, 70, 50, 30 and 10 mol% SiO2, Al2O3, MnO2, V2O5, La2O3, CeO2, Sm2O3, Eu2O3, Gd2O3 and Dy2O3 has been studied at different doses up to 500 kGy. Radiolytic decomposition of the nitrate is affected by the concentration of the oxide in the binary mixture as well as by the absorbed dose. The enhancement is up to 103 times at 90 mol% of the additive.G(NO2 ) values calculated on the basis of electron fraction of the nitrate decrease with the increasing concentration of the nitrate. A comparison ofG(NO2 ) for 90 mol% oxides shows decreasing trend as Gd2O3>Sm2O3≈Dy2O3> Eu2O3>CeO2>Al2O3>V2O5>SiO2>MnO2. ESR and TL measurements suggest the formation of radical species which interact with the radical species of nitrate causing enhanced decomposition by energy transfer mechanism.

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Abstract  

Gamma — radiolytic decomposition of sodium and potassium nitrates and its admixtures with respective cyanide and borate additives has been studied over a wide absorbed dose range from 675 to 500 kGy. The decomposition of nitrate increases with the nature and concentration of the additive in the admixture. The enhancement is more significant at >80 mol% of the additive.G(NO 2 ) values, calculated on the basis of electron fraction of the nitrate salt, decrease with increasing concentration of the nitrate. ESR spectral studies suggest the formation of radical species such as BO4 and BO 3 2− etc, in borates whereas in case of cyanide additive FH centres are produced. The radical species and colour centres so produced may then transfer their energy to nitrate and cause enhancement in decomposition. A comparison with other oxyanion additives shows thatG(NO 2 ) values decrease in the order PO 4 3− >B4O 7 2− >SO 4 2− >CO 3 2− . Similarly, the nature of the cation also affects the decomposition.

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Abstract  

The thermodynamic metal ligand stability constants of rare earths, La3+, Pr3+, Nd3+, Sm3+, Bu3+, Gd3+ and Tb3+, with N-p-chlorophenyl-m-substituted benzohydroxamic acids in dioxan-water (60–70%) media at 25° C, have been determined by the potentiometric method. The effect of basicity of the ligand, central metal ion and the order of stability constants are discussed. The order of stability constants of rare earths with the hydroxamic acids is La<Pr<Nd<Sm<Eu<Gd>Tb.

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Abstract

CdS/PMMA nano-composites at different weight percent of CdS (0, 2, 4, 6, and 8) have been prepared using solution casting method. The obtained nano-composites are characterized through the transmission electron microscope (TEM). The differential scanning calorimetry (DSC) measurements have been done on the nano-composites at different heating rates. The peak glass transition temperature is determined using the DSC thermograms. It is found that the glass transition temperature increases with the increase of CdS content up to 6 wt% and then decreases for higher weight percent (8). It is explained on the basis of molecular motion of PMMA, which is restricted when CdS is added into PMMA. An effort is also made to study the activation energy of glass transition in the case of nano-composites of different weight percent of CdS. Variation of activation energy with CdS nano-particle concentration has also been theoretically predicted by using an empirical relation. Thermal stability of these nano-composites has been explained with the help of activation energy in the glassy region.

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Study on curing of novolac epoxy resin

Polyamide hardener systems

Journal of Thermal Analysis and Calorimetry
Authors:
J. P. Agrawal
,
N. M. Bhide
, and
S. R. Naidu

The optimization of proportions of novolac epoxy resin, Dobeckot E4 and polyamide hardener, EH411 has been established by DSC and the data indicates that resin-polyamide, 100∶40 and 100∶50, appear to be optimum where ‘extent of cure’ is maximum. The kinetic parameters for these formulations have been evaluated using isothermal and dynamic modes by employing DSC.

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Solvent free reactions

Reactions of nitrophenols in 8-hydroxyquinoline–benzoic acid eutectic melt

Journal of Thermal Analysis and Calorimetry
Authors:
Preeti Gupta
,
Tanvi Agrawal
,
S. S. Das
, and
N. B. Singh

Abstract

Reactions of nitrophenols have been studied in the eutectic melt of 8-hydroxyquinoline–benzoic acid, where it reacted with 8-hydroxyquinoline. The reactions were also carried out in solution. The reaction products obtained from both the methods were characterized by FT-IR, differential scanning calorimetry, X-ray diffraction technique and microstructural investigations. The reaction products obtained from eutectic melt were analyzed for C, H, N. The results showed that reaction products obtained from both the methods are same. An attempt has been made to propose the overall mechanism of the reaction in the eutectic melt.

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Summary

A sensitive and reproducible HPLC method has been developed for quantitative analysis of telmisartan. The drug was separated from its degradation products on a C18 column at ambient temperature with methanol-water 80:20 (v/v), pH 4.0 (adjusted by addition of orthophosphoric acid), as mobile phase at a flow rate of 1.0 mL min−1. Under these conditions the retention time of telmisartan was 4.85 ± 0.05 min. Quantification on the basis of peak area was achieved by UV detection at 225 nm; calibration plots were linear in the concentration range 10–60 μg mL−1. When the method was applied to a pharmaceutical formulation there was no chromatographic interference from tablet excipients. The method was validated for precision, robustness, recovery, and limits of detection and quantification. The drug was subjected to acidic and alkaline hydrolysis, and oxidising, dry heat, wet heat, and photodegrading conditions. Because the method could effectively separate the drug from its degradation products, it can be regarded as stability indicating.

Open access

Carotenoids are important micronutrients required by humans for growth and development. Yellow maize among cereals possesses sufficient carotenoids, and thus, it is important to genetically dissect such traits for proper utilization in breeding programme. Twenty-one maize hybrids generated using novel inbreds with rare allele of β-carotene hydroxylase (crtRB1) that enhances kernel β-carotene, were evaluated at two diverse maize growing locations. Lutein, zeaxanthin and β-cryptoxanthin were positively correlated, while β-carotene showed negative correlation with other carotenoids. Grain yield did not show association with carotenoids. Preponderance of additive gene action was observed for lutein, zeaxanthin, β-cryptoxanthin and β-carotene. Experimental hybrids were much superior for kernel β-carotene compared to commercial hybrids. Based on SCA effects, high yielding experimental hybrids were identified for provitamin A and non-provitamin A carotenoids. These novel hybrid combinations of maize possessing rare allele of crtRB1 hold promise in maize biofortification programme to alleviate vitamin A deficiency and degenerative diseases in humans.

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Carotenoids play vital role in growth and development of human beings. Yellow maize kernel contains carotenoids that possess provitamin A and antioxidant activity. Multilocation based analyses of 105 maize inbreds of indigenous and exotic origin revealed wide genetic variation for lutein (0.2–11.3 μg/g), zeaxanthin (0.2–20.0 μg/g) and β-carotene (0.0–15.0 μg/g). For β-cryptoxanthin, low variation (0.1–3.3 μg/g) was observed. Carotenoids were quite stable over environments that played minor role in causing variation. The heritability (>90%) and genetic advance (>75%) were high for all the carotenoid components. Zeaxanthin showed positive correlation with lutein and β-cryptoxanthin, while β-carotene, the major provitamin A carotenoid, did not show correlation with other carotenoids. Kernel colour was positively correlated with lutein (0.25), zeaxanthin (0.47) and β-cryptoxanthin (0.44), but not with β-carotene (0.04). This suggested that visual selection based on kernel colour will be misleading in selecting provitamin A-rich genotypes. Inbreds with provitamin A and non-provitamin A carotenoids identified in the present study will help in development of biofortified maize hybrids.

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