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  • Author or Editor: R. Gupta x
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Abstract

Determination of compatibility in the amorphous phase for a two component blend is usually accomplished by analyzing for whether one notes one or two glass transitions. This can be complicated when one of the components is semicrystalline and its melting peak obscures the second glass transition. Quasi-isothermal differential scanning calorimetry (QiDSC) can be used to detect an obscured glass transition by allowing the semicrystalline component to melt and relax revealing the underlying glass transition of the other component. QiDSC is accomplished by performing a modulated temperature DSC experiment at a particular temperature and step ramping through the transitions of interest. For this study two systems are investigated. The first system is a model system based on a blend of polystyrene (PS) and a copolymer of vinylidene fluoride and hexafluoropropylene, P(VF2/HFP). The glass transition for the PS occurs at the same temperature as the melting point for the fluoro-copolymer. The second system is a fluoro-copolymer/acrylic dried latex. In both cases the hidden glass transition can be noted in the reversing heat capacity of the QiDSC analysis.

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Abstract  

Sorption of Li+, Cs+ and Sr2+ on hydrous titanium oxide and magnetite as a function of pH in the presence and absence of -rays has been studied. pH-titrations of the irradiated hydrous oxides have also been carried out. It has been shown that the sorption characteristics of these oxides are not altered by -irradiation and the uptake of metal ions is governed by the equilibrium pH of the solution. Certain physical changes observed on irradiating of the hydrous oxide samples in water are discussed.

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Abstract  

A selective method for the extraction of mercury(II) from hydrochloric acid solution with 3,4,4a,5-tetrahydro-3,3,4a-trimethyl-7-(substituted)-pyrimido [1,6-a]-benzimidazole-1-thiol, (PBT) is proposed. The extraction ability of the system was studied both in strongly acidic (6 mol dm–3 HCl) and alkaline (pH 12) media. The optimum extraction conditions were evaluated from a critical study of the effect of pH, PBT concentration and metal ion concentration. The probable composition of the species has been deduced from lg-lg plots and an extraction mechanism is suggested. A separation scheme is proposed. The method has been applied for the determination of Hg (II) in industrial waste water.

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Abstract  

Uranium and thorium mixed oxides are being prepared using natural U and Th for studies on fuels for Advanced Heavy Water Reactors, wherein composition of U and Th is specific and requires strict control in terms their contents and homogeneity. Chemical quality control necessitates accurate and precise compositional characterization of the fuel material by a suitable analytical method. Among various analytical methods for U and Th, instrumental neutron activation analysis (INAA) is one of the best methods for their simultaneous determination without chemical dissolution and separation. INAA methods using reactor neutrons namely thermal NAA and epithermal NAA were standardized for the determination of U and Th in their mixed oxides. Standards, synthetic samples and U–Th mixed oxide samples, prepared in cellulose matrix, were irradiated at pneumatic carrier facility of Dhruva reactor as well as at self serve facility of CIRUS reactor under cadmium cover (0.5 mm). Radioactive assay was carried out using a 40% relative efficiency HPGe detector. Both activation and daughter products of 238U (239U and 239Np) and 232Th (233Th and 233Pa) were used for their concentration determination. The method was validated by analyzing synthetic samples of 6–48%U–Th mixed oxides. The standardized method was used for the concentration determination of U and Th in 4–30%U–Th mixed oxide samples. Results of U and Th concentrations including associated uncertainties obtained from the INAA methods are presented in this paper.

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Abstract  

Recently scientists have investigated what statistical distributions can be used to describe the distribution of the number of authors per article.Ajiferuke has undertaken the most comprehensive study of this problem. He has found that by and large the Inverse Gaussian-Poisson distribution could describe most properly the observed authorship distributions. However, it is well known that this distribution is rather intricate, soRousseau tried to fit some simple one-parameter distributions to the number of authors of LIS articles. He has found that the geometric and the truncated Poisson distribution adequately describe these authorship data sets. The main purpose of the present paper is to continue these investigations and to analyse and test the viability of simple statistical distributions. As to (sub)fields where the single author dominates the results ofRousseau were corroborated: the truncated Poisson and the geometric distribution give often adequate fits to describe the number of authors. The Lotka distribution should be rejected. The truncated binomial distribution and the truncated negative binomial were investigated as well. However, it is not clear whether they are acceptable candidates.

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A set of thirty Calothrix strains, isolated from diverse geographical regions of India, were characterised using morphological and physiological attributes. Significant differences were observed among the Calothrix strains with regard to the shape and size of trichomes and individual cells within a filament, besides the activities of the enzymes involved in nitrogen metabolism. Informative morphological and physiochemical characters have been identified that could aid in differentiation and utilisation of Calothrix strains as bioinoculants or as sources of pigments.

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Grain and malt traits important for malting quality were studied on a set of 131 genotypes including two and six row types barley of indigenous and exotic origin grown at two locations for two seasons. Observations on seven grain and seven malt traits were recorded and malting was done with Phoenix® automatic micro-malting system. The correlation studies indicated that the hot water extract (HWE) is correlated with a number of grain (hectolitre weight, plump %, thin %, protein %, TGW and hull %) and malt (friability, homogeneity, wort viscosity, filtration rate and Kolbach Index) traits either positively or negatively. The multiple regression analysis indicated that hectolitre weight, TGW, hull content and malt friability can be used to predict HWE, the ultimately important trait with malting and brewing industry, in early generations of a breeding programme or for initial screening of germplasm accessions.

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Sixty-seven cultivars and advanced breeding lines from three major Indian wheat-producing zones were used to investigate the presence of 1RS.1BL translocation and high molecular weight glutenin subunits (HMW-GS), and to determine their effect on bread loaf volume and yield. The frequency of 1RS.1BL translocation was detected in 50.7% of the genotypes. Three, five and two allelic variations were observed at Glu-A1, Glu-B1, Glu-D1 , respectively. The genotypes with 1RS.1BL translocation were significantly high in grain yield and bread loaf volume than genotypes without 1RS.1BL translocation. The majority of genotypes (76.4%) possessing 1RS.1BL translocation had HMW-GS 5+10. It was concluded that the deleterious effect of rye translocation can be compensated by desirable HMW-GS at Glu-D1 locus.

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The application of immobilized enzyme for catalyzing various biotransformation processes is a widely used approach at present. This work mainly focused on the immobilization of polygalacturonase from Aspergillus niger Van Tieghem (MTCC 3323) on Nylon-6 by covalent binding, keeping in view its applicability in apple juice clarification. The immobilized enzyme was characterized in terms of kinetic parameters, thermal stability and reusability. The enzyme was immobilized onto glutaraldehyde-activated Nylon-6 by covalent binding and the efficiency of immobilization was found to be 40%. The immobilization yielded a protein loading of 70 μg g −1 of Nylon-6. Immobilized enzyme showed maximum activity at a temperature of 50 °C and pH 5.0. The enzyme was stable between pH 4.0–5.5. The immobilized enzyme could be reused through 4 cycles with almost 50% retention of its original activity. It had increased thermostability over its soluble form at 25 °C and 45 °C. Kinetic parameters K m and V max were found to be 7.6 mg ml −1 and 41.66 μmol of galacturonic acid/ml/min, respectively. The immobilized enzyme when used for apple juice clarification showed about 50% increase in transmittance of apple juice at 650 nm. This increase was observed at enzyme concentration of 20 U ml −1 apple juice, temperature 50 °C and incubation time of one hour. The optimization of these factors, which affect the stability and productivity of the immobilized system, resulted in an increase in enzyme stability and the possibility of economic application of immobilized enzyme at large scale apple juice clarification.

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Investigations of the thermal stability of detonating fuse containing 10 g pentaerythrol tetranitrate (PETN) revealed that the cord burnt under unconfinement at 403 K. Under confinement in a steel pipe or copper tube there was a partial detonation at 403 K. In order to characterize the thermal stability of PETN and pyrotechnic composition used in fuse head of electric detonators differential thermal analysis (DTA) was used.

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