Search Results

You are looking at 41 - 50 of 74 items for

  • Author or Editor: A. Khan x
Clear All Modify Search

Abstract  

The adsorption behaviour of99Mo in the form of molybdate and of99mTc in the form of pertechnetate on hydrated titanium dioxide was investigated at different molarities of hydrochloric acid. The adsorption capacity of molybdate on hydrated TiO2 is higher than on Al2O3. A99mTc-generator is suggested. This generator is based on the adsorption of (99Mo) molybdate on hydrated TiO2, at acidities of 0.05–0.1M. HCl.99mTc is eluted with 0.9% NaCl. Radionuclidic, radiochemical and chemical purities of the eluates were checked. This generator seems to have a great potential as compared to the traditional alumina generators.

Restricted access

Excess molar heat capacities of (L-glutamine aqueous solution+D-glutamine aqueous solution) were determined by using a differential scanning calorimeter at temperatures between 293.15 and 303.15 K. Excess molar heat capacities are all negative. Excess molar heat capacities decrease with increasing temperature.

Restricted access

Abstract  

Some plastic sheets manufactured or commercially available in Pakistan have been tested as radiation dosimeters for cobalt-60 -rays. Radiation induced colouration in the plastics have been measured spectrophotometrically. The results show that 2 mm thick clear poly(methyl methacrylate) (PMMA) can be used as radiation dosimeter up to 45 kGy when absorption measurements are made at 305 nm and 314 nm; whereas 1 mm thick clear poly(vinylchloride) (PVC) is useful up to 30 kGy when measured at 396 nm. The response of PMMA dosimeter is stable for at least 15 days and that for PVC for 30 days, when stored under ambient conditions after irradiation. Post-irradiation stability at various temperatures (–10 to 55°C) has also been studied.

Restricted access

Abstract  

Natural radioactivity in various types of marbles available in Rawalpindi/Islamabad industrial area have been assessed using HP(Ge) gamma-ray spectrometer. The concentration of 40K, 226Ra and 232Th ranges from 6.15 to 159.65 Bq.kg-1, 1.45 to 29.34 Bq.kg-1 and 1.16 to 6.28 Bq.kg-1, respectively. The radium equivalent activity lies between 5.56 to 33.42 Bq.kg-1. The average external and internal indices have been found to be 0.03 and 0.05, respectively. The average absorbed dose rate at 1 m was found to be 6.53 nGy.h-1. The estimated annual effective dose rate for whole body was found to be 0.04 mSv.y-1. These values are smaller than those predicted by UNSCEAR for normal background areas. The marbles analyzed pose less health hazard as compared to Pakistani baked bricks and other construction materials.

Restricted access

Effect of Graphene oxide (GO) was observed on Meloidogyne incognita and Macrophomina phaseolina and on the growth of lentil in pot experiment. Treatment of plants with 10 ml solution of GO with 125, 250 and 500 ppm concentration caused a significant increase in plant dry weight over control. Inoculation of plants with M. incognita or M. phaseolina caused a significant reduction in plant dry weight over uninoculated control. Treatment of plants with 125, 250 and 500 ppm GO and subsequent inoculation with M. incognita or M. phaseolina caused a significant increase in plant dry weight over plants inoculated without GO pretreatment. Treatment of 500 ppm GO caused a greater increase in plant dry weight of M. incognita or M. phaseolina inoculated plants followed by 250 ppm and 125 ppm. Numbers of nodules per root system were high in plants without pathogen. Inoculation of M. incognita or M. phaseolina caused reduction in nodulation. However, treatment of GO in all the three concentrations had no significant effect on nodulation in plants both with and without pathogens. Treatment of GO resulted in reduced galling, nematode multiplication and root-rot index. Greater reduction in galling, nematode multiplication and root-rot index were observed in plants treated with 500 ppm GO followed by 250 ppm and 125 ppm. Indices were reduced to 4, 3 and 2, respectively, when plants with M. phaseolina were treated with 125, 250 and 500 ppm GO. This study shows that the use of GO is useful for the management of M. incognita and M. phaseolina on lentil.

Restricted access

Abstract  

The problem of spectrochemical analysis of elements in solutions has been investigated for a number of elements across the periodic table using radioisotope-induced energy dispersive X-ray fluorescence method. In this study a low intensity109Cd X-ray source was used for characteristic X-ray excitation. Experimental parameters such as saturation thickness and critical thickness have been studied to evaluate their role in this method. Minimum detection limits, sensitivities and the nature of concentration calibration at critical thickness have been obtained as a function of Z to find the limits of the method. Results obtained have been discussed in the light of theories and potential areas of applicability of the method have been indicated.

Restricted access

A rapid, accurate, and sensitive reverse phase high-performance liquid chromatographic method was developed and validated for the simultaneous determination and quantification of glibenclamide and thymoquinone in rat plasma in the presence of internal standard (thymol). Chromatograms were developed with methanol, acetonitrile, and buffer (50:20:30, v/v/v) solvent system on a Symmetry® C18 (5 μm, 3.9 × 150 mm) column, and pH was adjusted to 4.5 with orthophosphoric acid. Mobile phase was pumped at a flow rate of 1.5 mL min−1 with 254 nm ultraviolet (UV) detection. Validation of the method was performed in order to demonstrate its selectivity, linearity, precision, accuracy, limits of detection, and quantification (LOD and LOQ). Standard curves were linear (r 2 = 0.996 and 0.999 for glibenclamide and thymoquinone) over the concentration range 0.5–50 μg mL−1. The coefficient of variation (CV) of < 6% and accurate recovery of 87.54–105.19% for glibenclamide and CV of <5% and accurate recovery of 86.08–103.19% for thymoquinone were found to be in the selected concentration range of 0.5–50 μg mL−1. The lower limits of detection and quantitation of the method were 0.109 and 0.332 μg mL−1 for glibenclamide and 0.119 and 0.361 μg mL−1 for thymoquinone, respectively. The within and between-day coefficients of variation were less than 7%. The validated method has been successfully applied to measure the plasma concentrations in a drug interaction study of glibenclamide with thymoquinone in an animal model to illustrate the scope and application of the method.

Open access

Abstract  

The proton particle induced X-ray emission (proton PIXE) technique has been employed to study the heavy element status (essential and toxic) in five different varieties of pulses commonly cultivated and consumed in Bangladesh. In this analysis, the samples were irradiated in air with 2 MeV protons having 30 nA beam intensity for characteristic X-ray excitation. For 40 C irradiations, the concentration of ten elements (K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Br, and Rb) was determined by comparison with a calibration obtained from the NBS orchard leaf standard, SRM 1571. In a comparative study with atomic absorption spectrophotometric (AAS) measurements of some elements in lathyrus sativus, the data were found to be in good agreement. The results obtained from the present study are discussed and compared with available data.

Restricted access

Abstract  

Neutron capture gamma-ray activation analysis technique has been used for the non-destructive analysis of Fe, Cr, Ni, Mn and B in stainless steel and iron ore samples. It has been shown that the use of low energy capture gamma-rays, ranging from 0.2 to 1.4 MeV, helps considerably in reducing the time of analysis. The problem of congestion of peaks due to compton continuum and the double and single escape peaks in this region of the spectrum has been overcome by using a Ge(Li) detector in conjunction with a 15.25 cm thick bifurcated NaI(Tl) annulus in anticompton mode. The results obtained by this technique have been compared with those of the chemical analysis.

Restricted access