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  • Author or Editor: S. Joshi x
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Assessment of the qualitative losses in different varieties of sorghum following Pyrilla perpusilla Walker infestation revealed the significant decrease in vitro dry matter digestibility of whole plant, leaves and stem by about 6.0, 3.5 and 3.0 per cent, respectively at more than 60 per cent infestation level and was mainly due to the corresponding increase in tannin content. The fibre components (NDF and ADF) were acting as an additional factor in reducing the dry matter digestibility. The dry fodder yield was also reduced by 46 to 53 per cent in different varieties of sorghum with an increase in infestation level from 0 to >60 per cent. The stem of all the varieties was more fibreous than the leaves as it had high content of NDF, ADF, cellulose and lignin. Leaves on the other hand had high amount of protein, total soluble sugars and reducing sugars than stem and were therefore more digestible than stem.

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A method for controlled potential coulometric determination of neptunium by titration with internally electrolytically generated iron(II) has been developed. The method involves oxidation of Np to Np(VI) by Ce(IV), destruction of excess of Ce(IV) by NaNO2 followed by determination of neptunium by reduction of Np(VI) to Np(IV) by internal generation of Fe(II). The method was employed for various neptunium solution samples and a precision of ±0.25% at 2–5 mg level of neptunium was obtained.

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Neutron activation analysis was used to determine129I in soil and grass samples around a reprocessing plant. The method involved wet oxidation of samples, using chromic acid, followed by distillation, collection of iodine in alkaline solution, loading on Dowex-1, irradiation and post-irradiation purification steps. The -activity of130I isotope of the purified samples was measured for quantitative determination of129I. The experimental results showed that129I and the129I/127I atomic ratio in soil samples varied from 1.09×10–4 to 5.33×10–3 pCi g–1 and 0.10×10–6 to 6.12×10–6, respectively. Further, the geometric mean of soil-to-plant transfer factor (Bv) for129I was found to be 0.16 which was comparable with other published values.

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Lead-210 dates are assigned to a sediment core retrieved from McKay Lake, Ottawa, Canada. Sediment mixing is found to have little, but discernible, influence on the age/depth profile. Consideration of mixing yields lower estimates of the derived ages, in agreement with the prediction based on a mathematical model. The inferred dates support the previous assignments based on Ambrosia horizon and the known occurrence of a catastrophic event. The procedures used in the calculation of the age profiles are fully described.

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Lactic acid fermentation of carrot as a method of preservation using different lactic acid bacteria, viz. Lactobacillus plantarum, Pediococcus cerevisiae and Streptococcus lactis subsp. diacetylactis as such and in sequence at different temperatures and with varying salt content (2, 2.5 and 3%) were employed in the fermentation of carrot. The differences in fermentation behaviour of different microorganisms were quite contrasting at 26 °C, but the sequential culture started deviating from the very first day and acidity increased up to 6 days. A temperature of 26 °C and salt concentration of 2.5% were the best for lactic acid bacteria (LAB) fermentation of Asiatic carrot as highest acidity (1.40% lactic acid), low pH and low reducing sugars were achieved in sequential fermentation. The LAB count of 7.8×10 8 CFU ml −1 was also higher at these concentrations coupled with higher sensory scores of the products. Among the fermentation types tried, sequential culture fermentation of the vegetables produced the product with higher acidity, low pH and reducing sugars. The sequential culture fermentation imparted the fermented products better flavour, texture and taste than other products fermented naturally or with lactic cultures of Pediococcus cerevisiae, Lactobacillus plantarum and Streptococcus lactis in single separate fermentation. Based on the overall and sensory quality evaluation, the fermented carrot product prepared with sequential culture was the best followed by the product prepared using natural microflora.

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Strawberry fruits of three cultivars viz. Camarosa, Chandler and Doughlas were used to prepare wine by four different methods (control, thermovinification, fermented on the skin and carbonic maceration). Physico-chemical characteristics of the cultivar Camarosa were rated superior to Chandler and Doughlas. The must from the fruits fermented on the skin gave the highest rate of fermentation and ethanol content. The application of various treatments improved the fermentation behaviour of treated strawberry musts compared to the control as revealed by their physico-chemical characteristics. Thermovinified wines had many desirable characteristics such as more total phenols, esters and colour with comparable amount of higher alcohols, volatile acids, ethyl alcohol, sugars and anthocyanin. The carbonic maceration resulted in wines with more alcohol, higher pH, lower acidity, lesser higher alcohol and volatile acids than other wines. Fermented on the skin treated wines were typical for higher amount of anthocyanin, lower reducing sugar and total sugar than the control wines. Thermovinified wines, irrespective of cultivars, scored the highest with respect to most of the sensory quality characteristics. Wines from Camarosa cultivar registered many desirable characteristics such as esters, optimum acidity, more red colour units with comparable contents of alcohol and total phenols, while Chandler cultivar had higher amount of ethyl alcohol, more phenols, anthocyanin than other cultivars. Some of these differences are correlated with their initial characteristics, while others have been influenced by method of vinification. Based on the physico-chemical and sensory qualities, the wines from cv. Camarosa was rated the best, though the wines of all the cultivars were acceptable.

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Thermal behavior of aqueous hydroxypropylmethylcellulose (HPMC)/surfactant mixtures was studied in the dilute concentration regime using micro-differential scanning calorimetry (DSC). The surfactant used was sodium n-dodecyl sulfate (SDS). The heat capacity of HPMC gel with various concentrations of SDS was much higher than that of the pure HPMC gel. The addition of SDS at different concentrations showed dissimilar influences on the gelation of HPMC; SDS at lower concentrations (≤6 mM) did not affect gelation temperature significantly except for enhancing the heat capacity whilst SDS at higher concentrations (≥6 mM) not only resulted in the gelation of HPMC at higher temperatures but also changed the pattern of the gelation thermograph from a single mode to a bimodal. On the basis of the observed thermal behavior of HPMC/SDS systems, the mechanism behind the sol-gel transition was discussed in terms of the properties of the surfactant and their influences on the extent of polymer/surfactant binding and polymer/polymer hydrophobic association. Gelation kinetics was analysed using the results from the DSC measurements. The kinetic parameters were determined.

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High activities of radium were observed in the spring waters of Tuwa in Panchamahal district of Gujarat state. These determinations have led to further studies on geochemical behaviour of uranium in the surface sediments of this region. Labile uranium from the surface of the sediment particles is leached with saturated solution of ammonium carbonate. Uranium is chemically separated from the leachates by cellulose column chromatography. Unusually high activity ratios of234U/238U in the range of 2.3 to 2.77 were observed on the surface of the particles. The core of the particles exhibited a ratio of 1.00 indicating soluble234U fraction has migrated.

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Gamma-radiolysis of KNO3 in the matrix of some sulfates, viz. Na2SO4, K2SO4, KNaSO4, KNaSO4: Eu, KNaSO4: Ce, K3Na(SO4)2, K3Na(SO4)2: Eu and K3Na(SO4)2: Ce has been studied at an absorbed dose of 30 kGy.G(NO 2 ) values calculated on the basis of electron fraction in all the sulfates are enhanced significantly. It is also affected by the nature of outer cation and the dopant lanthanide. Electron spin resonance (ESR) and thermoluminescence (TL) measurements show the formation of radical species SO 4 , SO 3 , O 3 , O 2 upon -irradiation. It is proposed that there radical species may transfer energy and interact with the radical species of nitrate (NO 3 2– , NO2, NO3 etc.) so as to enhance the decomposition. A possible mechanism has been proposed.

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