Determination of tryptophan in raw materials, rat brain and human plasma by RP-HPLC technique

This paper describes tryptophan (TRP) estimation in raw human plasma and rat brain by reversed-phase high-performance liquid chromatography (RP-HPLC). Estimation was carried out on a Purospher STAR C18 column using water-acetonitrile (90:10 v/v, at pH 2.7) mixture at a rate of 1.5 mL/min as mobile phase. Eluents were monitored at 273 nm by an ultraviolet detector. The method was linear (R(2) > 0.999), precise (intra-day and inter-day precision <2%) in the range of 0.25-20 μg/mL. The detection and quantification limits were 0.0144 μg/mL and 0.0437 μg/mL, respectively. In human plasma, Day 1 and Day 2 precision were 0.054-2.29% and 1.66-3.7%; whereas precisions in rat brain were 1.23-2.3% and 0.677-4.2%, respectively. The method was applied to study TRP level in human smokers and in arthritic rat brain. An efficient RP-HPLC method was developed for TRP determination that worked for clinical and research purposes.     

Gravitomagnetic Effects on Collective Plasma Oscillations in Compact Stars

The effects of gravitomagnetic force on plasma oscillations are investigated using the kinetic theory of homogeneous electrically neutral plasma in the absence of external electric or magnetic field. The random phase assumption is employed neglecting the thermal motion of the electrons with respect to a fixed ion background. It is found that the gravitomagnetic force reduces the characteristic frequency of the plasma thus enhancing the refractive index of the medium. The estimates for the predicted effects are given for a typical white dwarf, pulsar, and neutron star.     

Investigation on the impact of thermal performance of fluid due to hybrid nano-structures

Journal of Thermal Analysis and Calorimetry - This article explores the role of hybrid nano-particles in enhancing the thermal performance of Sutterby fluid over a two-dimensional body of variable...     

Semi pandiagonal magic 4 × 4-squares

It is proved that the set of all semi pandiagonal 4 × 4-squares precisely consists of 3456 squares belonging to three orbits under the faithful action of a group of order 1152 which is a semi direct product of symmetric groups.     

Alternate technique for simultaneous measurement of photoionization cross-section of isotopes by TOF mass spectrometer

New measurements of photoionization cross-sections of the lithium isotopes are reported employing a Time of Flight (TOF) mass spectrometer in conjunction with an atomic beam apparatus. Using a two-step selective photoionization and saturation technique, we have simultaneously measured the photoionization cross-section of the 2p excited state of both the isotopes Li⁶ and Li⁷ as 15±2.5 Mb and 18 ±2.5 Mb where as the corresponding number densities have been determined as N₀≈5.3×10¹⁰ atoms/cm³ and N₀≈6.2×10¹¹ atoms/cm³ respectively.     

Sorption of some azo-dyes on wool fiber from aqueous solutions

Sorption of some azo-dyes (acid violet 17, acid blue 90, acid red 1 and direct red 80) on locally available wool fiber from aqueous solution has been investigated as a function of shaking time, pH and dyes concentration as a function of temperature. Sorption isotherms for dyes on wool fiber were obtained. It was found that the increasing temperature induces positive effect on the sorption process. Isosteric heat of adsorption (q_st) have also been calculated at different surface coverage indicating that wool fiber used possessed heterogeneous surface with site of different activity. The results also indicate that initial sorption whether chemical or physical means, occurs first on the most active sites and then, as the concentration of dyes is increased, on sites of lesser activity.