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  • Author or Editor: S. D. Sivakumar x
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A field experiment was conducted at the Main Research Station, University of Agricultural Sciences, Dharwad, India, on medium black soils during the kharif (wet) season of 1999. The experiment was laid out in a randomized complete block design with varying N/P ratios (0.67 to 2.00) along with a control with a constant level of potassium (60 kg ha-1). The results revealed that the number of green leaves plant-1, the dry matter accumulation in the leaves, leaf area (dm2 plant-1) and leaf area index (LAI) increased up to the flowering stage (65 DAS) and thereafter declined. In the early stages (seedling and button stages) there was no significant variation with respect to the number of green leaves plant-1 among the treatments except in the control. Similarly, leaf area and LAI did not vary at the seedling stage. Treatments receiving N/P ratios of ?1.0 or 1.0 with higher doses of nitrogen (120 kg N ha-1) gave a significantly higher number of green leaves plant-1, leaf area and LAI as compared to N/P ratios of <1.0 and the control in later stages. The dry matter accumulation in the leaves (g plant-1) differed in all the stages, but higher values were recorded in these same treatments. Thus, due to the higher number of green leaves, higher LAI and greater dry matter accumulation in the leaves, the treatments with an N/P ratio of ?1.0 or 1.0 with 120 kg N ha-1 produced higher seed yields (3188 to 3554 kg ha-1) than other N/P ratios (2761 to 3009 kg ha-1). The highest yield (3554 kg ha-1) was recorded with an N/P ratio of 1.0 in the treatment receiving 120 kg N and 120 kg P2O5 ha-1. The correlation coefficients between these photosynthetic attributes and seed yield were also positive and significant.

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Abstract  

N,N,N′,N′-Tetraoctyl-3-oxapentanediamide (TODGA) is a versatile extractant for partitioning of fission products from highly active raffinate wastes. Its PVT properties are not available in literature. In this work, PVT properties of TODGA, estimated using group contribution method, are reported. A corresponding-states based equation as well as Wagner constants were also reported in the range of 273.15 K to critical temperature.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Shekhar Kumar, S. Balasubramonian, D. Sivakumar, U. Mudali and R. Natarajan

Abstract  

Di-(2-ethyl hexyl) phosphoric acid (hereafter referred as D2EHPA) is an important solvent for solvent extraction industry. It is also used in nuclear solvent extraction as a solvent for TALSPEAK and REVERSED TALSPEAK processes for actinide (III)–lanthanide (III) separation. Its PVT properties are not available in literature. In this work, group-contribution approach was used to predict its PVT properties as well as selected physical properties like normal boiling point.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Shekhar Kumar, S. Balasubramonian, Pranay Sinha, D. Sivakumar, U. Kamachi Mudali and R. Natarajan

Abstract  

Thermophysical properties of reversed TALSPEAK extractant (0.3 M D2EPHA/0.2 M TBP/n-dodecane) were not available in literature. Authors have experimentally measured and correlated several thermophysical properties of RT solvent like density, viscosity, refractive index, acid uptake and flash point. In this paper, results of these studies will be discussed in detail.

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Acta Chromatographica
Authors: M. Ganesh, B. Thangabalan, R. Patil, D. Thakur, A. Kumar Kumar, M. Vinoba, S. Ganguly and T. Sivakumar

Summary

A rapid, simple and validated reversed-phase high-performance liquid chromatographic method has been developed for analysis of oxaprozin in pharmaceutical dosage forms. Oxaprozin was separated on an ODS analytical column with a 45:55 (v/v) mixture of acetonitrile and triethanolamine solution (5 mm, pH 3.5 ± 0.05, adjusted by addition of 85% phosphoric acid) as mobile phase at a flow rate of 2.0 mL min–1. The effluent was monitored by UV detection at 254 nm. Calibration plots were linear in the range 160 to 240 μg mL–1 and the LOD and LOQ were 14.26 and 41.21 μg mL–1, respectively. The high recovery and low relative standard deviation confirm the suitability of the method for routine QC determination of oxaprozin in tablets.

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