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  • Author or Editor: R. Verma x
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A study was undertaken at the Directorate of Wheat Research experimental station, Karnal, India, to evaluate the effect of nitrogen (30, 60 and 90 kg/ha) and irrigation (one, two and three) on yield and grain quality traits of two and six row type malt barley genotypes. The mean grain yield significantly increased from 41.9 to 45.8 q/ha with increase in nitrogen dose from 30 to 90 kg/ha and 41.8 to 45.9 q/ha with increase in irrigations from one to three. The two and six row barleys had almost similar yield potential at higher nitrogen application and irrigation frequency but the six-row type had advantage at lower nitrogen and irrigation. Varietal effects were significant for all the traits, while N significantly affected only grain yield, spikes per unit area, 1000-grain weight and husk content. Irrigation effects were significant for bulk density, grain yield, spikes per unit area, and grains per spike. Traits like grain bulk density, proportion of bold and thin grains and husk content are mainly affected by variety and less affected by management practices.

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Zr-2.5 wt% Nb has been found to be better compared to Zircaloy-2 as coolant tube material in Canadu-PHW reactors but has a stringent specification of less than 0.5 mg/kg of chlorine. Instrumental neutron activation analysis (INAA) for the determination of chlorine in Zr-2.5 wt% Nb is not possible because of the high activity produced due to the determination of the matrix. Hence a radiochemical neutron activation analysis (RNAA) procedure has been developed for the determination of chlorine in this material. For the first time the chlorine determination at less than a ppm level by NAA is being reported in this paper, in a number of Zr-2.5 wt% Nb samples ranging from 0.1 to 2 mg/kg.

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A series of ternary complexes of the types M2L′2L″2;ML′2L″2 (M=Fe, Cu, Zn; L′=2-oxocyclopentane dithiocarboxylate; L″=pyridine, morpholine) and CuL′2H2O was prepared afresh. Except the iron complex, all are dimer and complexation is through the dithio moiety of the ligand L′. Their thermal decomposition was carried out in air at heating rate 10°C min−1 and it revealed that the dehydration of the aqua complex follows the same path as the carboxylates and the pyridine complexes have the tendency to follow one-step decomposition. The copper complexes are less thermally stable. The overall thermal stability of the 2-oxocyclopentanedithiocarboxylato complexes of the three metals with the volatile ligands was found to be in the order: (CuLmorph)2< CuL2H2O<(CuLpy)2<(ZnLmorph)2<(ZnLpy)2<FeL2py2. The thermogravimetric properties of the complexes have been studied and the data were subjected to kinetic analysis. The values of n, E, A and ΔS# have been approximated and compared. Any formation of bridged structure is not indicated in the first step case.

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A series of substituted triphenylphosphane complexes of the type CdL2X2 (L= triorthotolylphosphane or trimetatolylphosphane; X=Cl, Br or I) and HgL2X2 (L=triphenylphosphane or triorthotolylphosphane) was prepared fresh. The thermal decomposition was carried out in air with heating rate programmed at 10�C min−1 and it revealed that the complexes with ortho derivative were less stable and the triphenylphosphane moiety leaves along with halogen in the first step. All the complexes were stable up to 210�C. However, the stability order of the tetrahedral complexes was X=Cl>Br. Values of n, E, lnA and ΔS # have been approximated and compared. Complexes having Br have higher E a, lnA and ΔS # values than that having Cl.

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Summary A comparative study of the non-isothermal decomposition of the dl-lactate hydrates of magnesium, calcium and strontium has been made with that of the dl-lactate hydrates chromium(III), manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) keeping dry air as the purge gas and the heating rate maintained at 10 K min-1. While the dl-lactates of manganese(II), cobalt(II) and copper(II) followed single step decomposition scheme suggesting that dehydration and decomposition steps overlapped, the dehydration steps of the other compounds were distinct. &-T plots of none of the dehydration steps showed any induction period, indicating no physical desorption, nucleation or branching. Neither the & max-values nor the onset temperatures of the dehydration steps did show any pattern. The TG data of the dehydration steps have also been analyzed using the Freeman-Carroll, Horowitz-Metzger, Coats-Redfern, Zsakó, Fuoss-Salyer-Wilson and Karkhanavala-Dharwadkar methods. Values of order of reaction, activation energy and Arrhenius factor have been approximated and compared. There are similarities in the activation energy values for the dehydration steps (< 60 kJ mol-1 in general). It is higher with group 2 metals and lower in transition metals (maximum in magnesium and lowest in chromium and iron lactates). In cases of overlapping of dehydration and decomposition steps, the activation energy values are on the lower side with the same trend (lower in cobalt and copper cases).

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Polyaniline sorbed with microgram quantity of mercury was prepared and its homogeneity and stability with respect to mercury was evaluated over a period of time. The volatilisation loss of mercury during and after neutron irradiation was studied. It was found that polyaniline was homogeneous and stable with respect to mercury. No loss of mercury from polyaniline was observed during and after neutron irradiation. Thus polyaniline sorbed with mercury can serve as a good standard for neutron activation analysis of mercury.

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The results obtained showed that there was severe competition between potato and the predominant weed species Coronopus didymus, Chenopodium album, Fumaria parviflora, Melilotus indica and Spergula arvensis. Competition by other weed species was nominal. The maximum reduction in tuber yield due to weed competition was 50.5% in 1997–98 and 63.4% in 1998–99. Weed control treatments lowered the weed density and weed biomass and scaled up tuber yield in both the years, but their effect on weed species differed. Metribuzin killed all the Chenopodium album plants and gave excellent control of Coronopus didymus (94%) and effective control of other weed species. Pendimethalin inhibited the germination of Chenopodium album, gave good control of arvensis and lowered the density of other weed species. Fluchloralin completely inhibited the germination of Fumaria parviflora and gave good control of Chenopodium album and Spergula arvensis, but was least effective against other weed species. The highest yield was recorded in the weed-free treatment, which was significantly superior to all other treatments. Hand weeding + earthing up, isoproturon (1.0 kg/ha), metribuzin and pendimethalin caused an identical increase in tuber yield, which was significantly higher than the increase in the rest of the treatments. Atrazine at 0.25 kg ha –1 resulted in a higher increase than when applied at 0.5 kg ha –1 . Fluchloralin, paraquat and paddy straw mulch boosted up production, but the increase in tuber yield was not significant.

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A radiochemical neutron activation analysis procedure for the determination of Ta, W, Ir, Pt, Au, Cu, Cr, Co and Zn in lithium niobate has been developed. The method involves a one-step removal of radioactive nuclides of Nb, Ta and W representing the dominating radioactivity of the irradiated sample. After irradiation, the sample is fused with inactive carriers and Na2O2 in a nickel crucible. The fused cake is dissolved in HCl–H2O2 and Nb, Ta and W are homogeneously precipitated. The impurities are separated by combinations of precipitation and ion-exchange separations for precise -ray measurements with an overall chemical yield of 70% to 90%. The results are discussed.

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The nature and composition of complexes formed by the reaction of Fe(III), Cr(III), Zn(II), and Co(II) with potassium pentacyanonitrosyl manganate K3 [Mn(CN)5NO] has been investigated by radiometric method. The metals form 1∶1 complexes with K3 [Mn(CN)5NO], the optimum pH for maximum precipitation being 3.6 for Fe(III), 7.3 for Cr(III), 5.4 for Zn(II), and 8.3 for Co(II). The solubility of the complexes as computed from activity at maximum precipitation point follows the order: chromium complex > iron complex > cobalt complex > zinc complex. The radiometric titration curves also show the formation of colloidal precipitates with dilute Zn(II) solutions.

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