Search Results

You are looking at 1 - 10 of 81 items for

  • Author or Editor: A. Kumar x
Clear All Modify Search

Gene effects were analysed using mean stomatal number and specific leaf weight of 12 populations, consisting of both parents (P 1 and P 2 ), F 1 , F 2 , first backcross generations (BC 1 and BC 2 ), second backcross generations (B 11 , B 12 , B 21 , B 22 ) and backcross selfed generations (B 1 s and B 2 s) of four crosses involving three drought-tolerant and three drought-susceptible cultivars of Triticum aestivum L. to determine the nature of gene action governing stomatal number (SN) and specific leaf weight (SLW) through generation mean analysis in moisture stress (E 1 ) and moisture non-stress (E 2 ) environments. The digenic epistatic model was found to be inadequate for stomatal number and the additive-dominance model was found to be adequate for specific leaf weight in most of the crosses. Additive gene effects were predominant for SLW, while for SN both additive and dominance components of variance were important. Epistatic effects, particularly the additive × dominance (j) type of interaction, were present for both the characters. The duplicate type of epistasis was observed for stomatal number in the cross VL421/HS240 in the moisture stress environment. Significant heterosis was observed for the crosses Hindi 62/HS240 and VL421/HS240 over the standard check (SC) in the moisture stress environment (E 1 ) for both the characters. Genotype-environmental interactions and/or differential gene expression appeared to account for the different results found between environments. Hybridization systems, such as biparental mating and/or diallel selective mating, could be useful for the improvement of these traits, which would help in identifying drought-tolerant progenies.

Restricted access

Gene effects were analyzed using mean excised-leaf water loss and relative water content of 12 populations viz., both parents (P 1 and P 2 ), F 1 , F 2 , first back cross generations (BC1 and BC2), second back cross generations (B 11 , B 12 , B 21 , B 22 ) and back cross-selfed generations (B 1 s and B 2 s) of four crosses involving three drought tolerant and three drought susceptible cultivars of Triticum aestivum L. to determine nature of gene action governing excised-leaf water loss (ELWL) and relative water content (RWC) through generation mean analysis under rainfed (E1) and irrigated (E2) environments. Both additive-dominance and digenic epistatic model were found to be inadequate in all the crosses for ELWL and in most of the crosses for RWC to explain genetic variation among the generation means. Additive gene effects were predominant for RWC, while for ELWL both additive and dominance component of variance were important. Epistatic effects, particularly dominance × dominance (1) type of interaction was more predominant for RWC, while additive × additive(i) for ELWL. Duplicate type of epistasis was observed in the crosses Hindi 62/HS240 and VL421/HS240 for RWC and in the cross S4/HPW89 for ELWL under both the environments. Complementary type of epistasis was observed only in the cross VL421/PBW175 for ELWL under E1. Hybridization systems, such as biparental mating and/or diallel selective mating could be useful for improvement of these traits which would help in isolating drought tolerant progenies.

Restricted access

Abstract

Calorimetric measurements have been performed in glassy Se90M10 (M=In, Te, Sb) alloys to study the effect of In, Te and Sb additives on the kinetics of glass transition and crystallization in glassy Se90M10 system. Kinetic parameters of glass transition and crystallization such as the activation energy of glass transition (E g), the activation energy of crystallization (M c), the order parameter (n), the rate constant (K), etc. have been determined using different non-isothermal methods. The composition dependence of the activation energies of glass transition and crystallization processes is also discussed.

Restricted access

Abstract  

Different methods have been used by various workers to determine the activation energy of thermal crystallization (E c) in chalcogenide glasses using non-isothermal DSC data. In the present work, the crystallization kinetics of two important binary alloys Se80Te20 and Se80In20 is studied using non-isothermal DSC data. DSC scans of these alloys have been taken at five different heating rates. The values of activation energy of crystallization (E c) have been determined by four different methods, i.e., Kissinger's method, Matusita-Sakka method, Augis-Bennett's method and Ozawa's method, have been used to calculate E c. The results obtained have been compared with each other to see the effect of using different methods in the determination of E c.

Restricted access

Abstract  

The crystallization kinetics of a-Se80–xTe20Cdx (x=0, 5, 10, 15) and a-Se80–xTe20Gex (x=5, 15, 20) alloys has been studied by an isothermal method. For this purpose, conductivity measurements are done during isothermal annealing at various temperatures between the glass transition and crystallization temperatures. Avrami’s equation is used to calculate the activation energy of crystallization (E c) and order parameter (n). It is shown that Avrami’s theory of isothermal crystallization correctly describes the crystallization kinetics in the present alloys. The composition dependence of E c in these alloys has also been discussed.

Restricted access

Abstract

This work reports the effect of Ge, Sb, Sn additives on the thermally activated glass to crystal phase transition in binary Se90In10 alloy. Differential scanning calorimetry (DSC) technique is used for this purpose. Different kinetic parameters of glass/crystal transformation have been calculated. The results are explained using the chemical bond approach for the covalent network of such glasses.

Restricted access

An extruded product was made based on oats and dried green pea using central composite rotatable design. Effects of incorporation level of oat flour (OF, 15.86 to 44.14%) and dried green pea flour (DGPF, 7.93 to 22.07%) on the physical and functional characteristics of extruded products based on composite flour were studied using response surface methodology. Second order polynomial equation was used to describe the effect of OF and DGPF on lateral expansion (LE), bulk density (BD), water solubility index (WSI), water absorption index (WAI), and hardness (HD). Results indicated that OF had negative effect on LE, while positive effect on BD, WSI, WAI, and HD. On increasing DGPF, LE and WSI increased, but it had negative effect on BD, WAI, and HD. Numerical optimization resulted in 41.91% OF and 7.93% DGPF to produce acceptable extrudates. The results suggest that oats and dried green pea flour can be extruded with rice flour and corn flour into an acceptable snack food.

Restricted access

Abstract  

The phase analysis of the rusts generated beneath the primer containing micaceous iron oxide (MIO) and micaceous iron oxide in combination with red lead (RL), zinc phosphate (ZP), basic lead silicochromate (BLSC) and zinc chromate (ZC) has been carried out by Mössbauer spectroscopy at room temperature. The rust beneath the coating obtained after immersion of the painted panel for six months in 3% NaCl, consists mainly of nonstoichiometric magnetite together with small fractions of γ-, α-FeOOH except in the case of panel painted with RL containing MIO showed only a central doublet indicating the formation of γ-FeOOH and SPM α-FeOOH. Non-stoichiometry of magnetite as calculated from the ratio of B/A sites of the peaks of magnetite in the spectrum has been found depending on the nature of anticorrosive pigment present in the primer coating. The order of non-stoichiometry has been found to be in order of ZC>BLSC>ZP>MIO.

Restricted access

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.

Restricted access
Authors: Y. Gautam, S. Sharma, A. Sharma, V. Kumar, J. Kumar, A. Kumar, A. Hegde and P. Sarkar

Abstract  

Guidelines for the assessment of internal doses from monitoring suggest default measurement of uncertainties (i.e. lognormal scattering factor, SF) to be used for different types of monitoring data. In this paper, SF values have been evaluated for internal contamination due to 60Co in two cases using whole body counting data. SF values of 1.04 and 1.03 were obtained for case I and II, respectively while SF value of 1.03 was obtained using bioassay data for case I. SF evaluated is in good agreement with the default values given by IDEAS guidelines. The present study also presents the follow up study of a case I of 60Co internal contamination using whole body counting and bioassay analysis. The effect of medical intervention applied on the subject is studied. Medical intervention of d-Penicillamine (250 mg × 4 daily) was orally administered from 13th day of initial exposure for about a fortnight, which showed reduction of activity present by 33.4% through urine.

Restricted access