Let A be a nonnegative regular summability method. In this paper we deal with various subspaces of A-statistically convergent sequences by using the rate of convergence concept. We show, under certain conditions, that these subspaces cannot be endowed with a locally convex FK-topology. We also describe multipliers for bounded A-statistically convergent and bounded A-statistically null sequences with the appropriate rate and provide a Steinhaus type result.
Authors:T. Jabbar, M. Subhani, K. Khan, A. Rashid, S. Orfi, and A. Khan
A study on the concentration of natural and fallout radionuclides in environmental samples collected from different localities of Islamabad was performed. For the determination of gamma-emitters such as 238U, 232Th, 40K and 137Cs high purity germanium (HPGe) detector was used while for the analysis of 90Sr, a beta-emitter, liquid scintillation counting system was used. The indoor absorbed dose rate was measured by a CaF2 : Dy thermoluminescence detector. Other radiation parameters were also determined to evaluate the radiation hazard. All the results were well within the permissible limits showing that there is no radiation hazard in the environment of Islamabad.
Authors:A. Rahman, K. Khan, G. Al-Khaledi, I. Khan, and Sreeja Attur
Cognitive impairment is a common feature of both lead exposure and hyperphosphorylation of tau. We, therefore, investigated whether lead exposure would induce tau hyperphosphorylation. Wistar rat pups were exposed to 0.2% lead acetate via their dams’ drinking water from postnatal day 1 to 21. Lead in blood and brain were measured by atomic absorption spectrophotometry and the expression of tau, phosphorylated tau and various serine/threonine protein phosphatases (PP1, PP2A, PP2B and PP5) in the brain was analyzed by Western blot. Lead exposure significantly impaired learning and resulted in a significant reduction in the expression of tau but increased the phosphorylation of tau at Ser199/202, Thr212/Ser214 and Thr231. PP2A expression decreased, whereas, PP1 and PP5 expression increased in lead-exposed rats. These results demonstrate that early postnatal exposure to lead decrease PP2A expression and induce tau hyperphosphorylation at several serine and threonine residues. Hyperphosphorylation of tau may be a mechanism of Pb-induced deficits in learning and memory.
Authors:Z. Chaudhry, H. Khan, K. Khan, M. Aslam, A. Jabbar, and S. Orfi
Specific activity of natural radionuclides; 226Ra, 232Th and 40K were measured in the agricultural soil of eastern salt range of Pakistan using gamma ray spectrometry. The soil samples were collected within the ploughing region (up to 12 cm depth) and processed before analysis. The average specific activities of different radionuclides in the dry mass of soil samples were: 40K, (666 Bq/kg), 226Ra (51 Bq/kg), and 232Th (59 Bq/kg). The average outdoor terrestrial absorbed dose rate in air from gamma radiation one meter above ground surface was found to be 93 nGy/h.
Authors:M. Younis, M. S. Subhani, K. Khan, and S. D. Orfi
A systematic study of natural and fall-out radionuclides was carried out with the environmental samples of soil, vegetation
and water from some regions of North West Frontier Province (NWFP) of Pakistan. The pretreatment of the samples was performed
in the laboratory using IAEA recommended methods. The analysis of gamma-emitters such as 40K, 226Ra, 232 Th and 137Cs was performed with a high purity germanium detector (HPGe). For the determination of 90Sr, a liquid scintillation counting system was used. The average specific activities of 40K, 226Ra, 232 Th and 137Cs have been found to be 307±101 Bq . kg-1, 10.2±3 Bq . kg-1, 24±6 Bq . kg-1 and 2.8±1.3 Bq . kg-1, respectively, in soil samples. Vegetation samples have smaller values of specific activities and even the analysis of water
samples showed values less than LLD for earlier reported radionuclides. Other parameters like hazard indices, radium equivalent
activities, absorbed dose rates and effective dose equivalents have also been determined. All these parameters have values
less than their respective limiting values representing that the surveyed areas have no significant hazard from health point
of view. Analysis of 90Sr for all the samples showed results below LLD. The present study provides a general background of the detectable radionuclides
for the surveyed areas that will be helpful in any radiological emergency.
Authors:T. Jabbar, K. Khan, M. Subhani, and P. Akhter
Assessment of 90Sr is of great interest owing to the fact that this artificially produced radionuclide has high radiological importance because
of its high fission yield, chemical similarity to calcium and its relatively long biological and physical half-life. To assess
the likely hazard to population, low level 90Sr in environmental samples is determined using pre-equilibrated tri-butyl phosphate (TBP) solvent and extraction-liquid scintillation
procedure. 90Y is selectively extracted from nitric acid solution into TBP solvent and stripped into aqueous phase as oxalate. The activity
is finally measured by low level liquid scintillation counter using Cerenkov radiation. The specific activity is found only
in three vegetation samples with average value of 2.86±1.7 Bq·kg−1 of dry weight. In all other samples analyzed, the activity is below the detectable limit, i.e., 0.03 Bq. Results obtained
are comparable with other areas of Pakistan. The chemical recovery of 90Y varies from 75 to 90% for soil, vegetation and water. The present study provides a general background of the detectable
radionuclide for the surveyed area that will be helpful in any radiological emergency.
The investigation was concerned with the effects of water stress on the yield and yield components of wheat grown under rainfed conditions in Rawalakot, Pakistan. A pot experiment was conducted with four wheat genotypes, Inqlab-91, Chakwal-97, Rawal-87 and Kohsar-95, tested against five irrigation levels with drought imposed at different growth stages including control, terminal drought, post-anthesis drought, three irrigations and pre-anthesis drought. The parameters studied were flag leaf area, ear stalk length, number of grains per spike and grain yield per pot. Flag leaf area and ear stalk length exhibited a significant reduction of 14 and 36%, respectively, when wheat was subjected to water stress. The proportional reduction in yield was 40% with three irrigations and 98% in the case of pre-anthesis drought depending upon the extent and degree of stress. Results showed that wheat could withstand and tolerate drought only up to anthesis, after which water stress resulted in the complete failure of the crop. It could be deduced that the critical stage for moisture in wheat started 60 days after germination, and became more severe at 90 days, i.e. at the anthesis stage. Among the genotypes, Inqlab-91 was found to be more tolerant of drought and could thus be a good option for further testing and recommendation for rainfed areas.
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.