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- Author or Editor: I. Singh x
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Abstract
Six isomeric dimethyl anilinium bromides (DMABr) have been prepared and characterized by elemental and spectroscopic studies. Thermal decomposition of these salts has been studied by TG and simultaneous TG-DTA techniques. Kinetic parameters have been evaluated from isothermal TG data using contracting area and contracting cube equations. The decomposition pathways have also been suggested which involves simultaneous sublimation (at lower temperature) and dissociative vaporization/decomposition (at higher temperature).
Abstract
Three phenylenediammonium sulfate (PDAS) salts were prepared under solvent free conditions and characterized by gravimetric, spectroscopic and elemental analyses. Thermal decomposition studies of the salts have been investigated using TG (static air), TG/DTG and DSC (inert atmosphere). The thermal decomposition pathways have also been suggested and it has been found that PDAS salts on heating under vacuum in solid state give diaminobenzene sulfonic acids (DABSA) via proton transfer.
Ninety-nine wheat cultivars from six different agro-climatic zones of India were analyzed for the Vrn-1, Vrn-2, Vrn-B3, Vrn-4 and Ppd-D1 composition with DNA sequenced based allele specific or linked markers for the above-mentioned genes. A majority of the germplasm carried the dominant Vrn-A1a allele alone or in combination with Vrn-B1 and Vrn-D1. The three dominant genes were cumulatively present in 30 cultivars among all the zones, whereas double dominant combination, Vrn- A1/Vrn-B1 was identified in 18 cultivars, Vrn-A1/Vrn-D1 in 6 cvs and Vrn-B1/Vrn-D1 in 16 cvs. The combination of the dominant alleles of all three genes was most frequent in cvs of Northern Western Plains Zone. Northern Hill Zone had vrn-B1 and vrn-D1 alleles in higher proportions compared to the dominant alleles Vrn-B1 and Vrn-D1 indicating successful spring/winter wheat cross breeding. All of the cvs had the recessive Vrn-B3 allele. Most of the cvs had photoperiod insensitive allele in all the zones and only 9% cvs possessed the photoperiod sensitive allele (b) of the Ppd-D1 gene. This information will be useful in selecting parental lines for crossing to maximize diversity at these loci and for future molecular marker assisted breeding for cultivar improvement.
The role of antibiosis components and antioxidant defense of rice genotypes, namely CR3006-8-2, RP4918-221, KAUM182-1, T12, IHRT-ME-25, W1263, Ptb33 (resistant check) and TN1 (susceptible check) was studied by phenotyping them against brown planthopper (BPH). Three genotypes, namely KAUM182-1, RP4918-221 and CR3006-8-2 were resistant to BPH and significantly low damage score (1.97–3.00); honeydew excretion area (46.76–49.64 mm2); nymphal survival (60.60–66.40%) and growth index (2.98–3.86) was recorded on them. Higher constitutive and induced level of soluble phenolics, peroxidase and polyphenol oxidase was observed in resistant genotypes without and with BPH infestation. A negative relationship between honeydew excretion, nymphal emergence, growth index and nymphal survival was observed with these biochemical constituents. Likewise, a reverse trend was observed between nymphal development period and biochemical constituents. These genotypes have emerged as a new source of resistance to BPH which can be used in hybridization programme to breed durable BPH resistant rice varieties.
Abstract
Three dimethylanilinium sulfates (DMAS) have been prepared and characterised by elemental and spectral studies. Thermal decomposition of these salts has been studied by TG and simultaneous TG-DTG technique and kinetic parameters were evaluated from both dynamic and isothermal TG data using mechanism based kinetic equations. The thermal decomposition pathways have also been suggested and it has been found that DMAS salts give dimethyl aminobenzenesulfonic acids (DMABSA) via solid state reaction. The primary step in the thermal decomposition involves proton transfer followed by sulfonation.
Some transition metal nitrate complexes with hexamethylenetetramine
Part LV. Preparation, X-ray crystallography and thermal decomposition
Abstract
Three hexamethylenetetramine (HMTA) metal nitrate complexes such as [M(H2O)4(H2O-HMTA)2](NO3)·4H2O (where M=Co, Ni and Zn) have been prepared and characterized by X-ray crystallography. Their thermal decomposition have been studied by using dynamic, isothermal thermogravimery (TG) and differential thermal analysis (DTA). Kinetics of thermal decomposition was undertaken by applying model-fitting as well as isoconversional methods. The possible pathways of thermolysis have also been proposed. Ignition delay measurements have been carried out to investigate the response of these complexes under condition of rapid heating.
Abstract
In northern part of Indian sub-continent, As related environmental and health issues receive attention from all over the world. Forty-eight sediment samples were collected from the Ganga Alluvial Plain (GAP) and its weathering products (from the Gomati River) for the study of As distribution and mobilization. These sediment samples were analyzed by Instrumental Neutron Activation Analysis (INAA) method using Cirus Research Reacter of Bhabha Atomic Research Centre, Mumbai. Average As concentrations in the GAP sediments (10.44 mg kg−1), the Gomati River bed sediments (1.36 mg kg−1) and the Gomati River suspended sediments (5.30 mg kg−1) were reported. Significant decrease of As content from the alluvial sediments to the river sediments is a clear indication of its mobilization by chemical weathering processes of mineral biotite. Present study demonstrates the importance of INAA for quantification and mobilization of As and improves our understanding related to As related environmental issues in northern India and elsewhere.
Studies on energetic compounds
IV. Thermal explosion of ring-substituted arylammonium perchlorates
Thermal and explosion characteristics of ring(mono) substituted arylammonium perchlorates (RSAP) are studied by DTA, impact and friction sensitivity measurements. Exothermic decomposition temperature (T d) from DTA curves and impact sensitivity data (h 50%) were found to be linearly related to the Hammett substituent constant (σ+,σ−) andpK a values of the corresponding arylamines. A reaction scheme, based on the formation of reaction intermediates during decomposition and explosion, accounting for the products, is proposed which, involves proton transfer as the rate determining process and evolution of ammonia. It seems that oxidation-reduction reactions between the arylamine/substituted benzene and HClO4 or its decomposition products cause explosion.
