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Current Issue
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Vol
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Vol. 47, No. 1 (2010)
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Accepted Papers
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TRANSVERSE MOMENTUM PHYSICS: FROM SPS TO LHC ENERGIES COMPARISON TO THE DATA ON p-12C -INTERACTIONS AT Pp-= 40 GeV/c
Yashar Huseynaliyev
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The aim of the presented analysis is to review the transverse momentum physics in SPS CERN, RHIC BNL and LHC CERN energies and investigate inclusive hadron production in π−12C interactions at Pp-=40GeV/c. We focus on pT dependence of the nuclear modification factor (R) for proton and charged π meson production. We demonstrate that the results are in agreement with the SPS and RHIC ones.
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A NEW OBJECTIVE CRITERION FOR IRIS LOCALIZATION
A. Basit
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Iris localization is the most important step in iris recognition systems. For commonly used databases, exact data is not given which describe the true results of localization. To cope with this problem a new objective criterion for iris localization is proposed in this paper based on our visual system. A specific number of points are selected on pupil boundary, iris boundary, upper eyelid and lower eyelid using the original image and then distance from these points to the result of complete iris localization has been calculated. If the determined distance is below a certain threshold then iris localization is considered correct. Experimental results show that proposed criterion is very effective.
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STATISTICAL ANALYSIS OF THE DATA FROM US CONTINENTAL TESTS CONDUCTED DURING 1961 - 1992
M. Wasim
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The paper presents statistical analysis of the data obtained from US continental tests conducted during 1961 - 1992. The analysis summarizes the types of the tests, their yield, radioactivity released and the radionuclides emitted during the tests. The application of principal component analysis shows that some radionuclides are emitted in correlation with other radionuclides, which need not from the same decay chain. The overall analysis puts emphasis on the detection of radioiodines and radioxenons both for event screening and for event backtracking.
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STATISTICAL DATA ANALYSIS OF GAMMA-RAY BACKGROUND SPECTRA FOR QUALITY ASSURANCE IN GAMMA-RAY SPECTROMETRY
M. Wasim
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Twenty five gamma-ray spectra were accumulated in gamma-ray spectrometry laboratory located at Chemistry Division, PINSTECH, Islamabad for a period of three years. Different background components with their variation with time have been discussed in the paper. It has been shown that the natural component of the background radiations can be reduced with a better design of the shielding, however, the component from the fission or activation products can not be reduced with increased shielding around the detector but with a better shielding material.
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INFLUENCE OF pH ON UPTAKE AND BIOACCUMULATION OF RADIOCESIUM (137Cs) IN THE GREEN PERNA VIRDIS
A. Mashiatullah
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Radiotracer experiment was conducted to assess the influence of pH on uptake rate and bioaccumulation of 137Cs from dissolved phase in soft parts of green mussels (Perna viridis) collected from Karachi Coast, under controlled laboratory condition. Green mussels of size 5–7 cm were subjected to radiocesium activity of 24 KBq L-1 under three pH levels i.e., 7.5, 8 and 8.5. The uptake of 137Cs was monitored for a period of seven days. The results showed that uptake and bioaccumulation of 137Cs in mussels was dependent on pH levels. Higher bioaccumulation factors and uptake rates were found at pH 8.
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Conditionally Accepted Papers
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Dominant Conduction Mechanism and the Effects of Device Temperature on Electrical Characteristics of Al/ZnPc/n-Si structures
A. Hussain
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Aluminum/Zinc Phthalocyanine/n-Si metal semiconductor contact with organic interfacial layer have been developed and characterized by Current–Voltage-Temperature (I-V-T) measurements, to study its junction and charge transport properties. The junction parameters, of diode ideality factor (n), barrier height (fb) and series resistance (RS), of the device are found to shift with device temperature. The barrier height is found to increase and the series resistance is found to decrease with increasing device temperature, whereas the diode ideality factor increases up to the device temperature of 323K and it decreases for higher device temperatures. The activation energy of the charge carriers is found to be 52meV and the peak of interface state energy distribution curves is found to shift in terms of Ess-Ev value from 0.622 eV to 0.827 eV with increasing device temperature. The data analysis implies that the Fermi level of the organic interfacial layer shifts as function of device temperature. In terms of dominant conduction mechanism, the I-V-T data analysis confirms the fit of data to the relationship log (IV4) µ V1/2 in the device temperature range of 313K to 343K and the Poole-Frenkel type is found to be the dominant conduction mechanism for the hybrid device.
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FABRICATION OF LaNiO3 CONDUCTING ELECTRODE ON Si (100) SUBSTRATE BY PLD
M. S. Awan
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Abstract
Polycrystalline perovskite LaNiO3 (LNO) conductive layer was fabricated on SrTiO3(STO)/Si(100) substrate by pulsed laser deposition (PLD) technique. X-ray diffraction (XRD), electrical resistivity, field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were employed to characterize the films. Films were deposited under controlled atmosphere of oxygen gas and its affect was studied on the phase formation and electrical properties. STO was used as buffer layer. It exhibits polycrystalline [(100), (110)] growth when deposited at 700oC substrate temperature under 1x10-2 Torr oxygen partial pressure. The STO film was smooth and well crystallized with average grain size ~100 nm. LNO films deposited at 600oC substrate temperature epitaxially followed the STO/Si(100) substrate and has low resistivity, good metallic characteristics and very smooth surface. Oxygen partial pressure affects both the crystallinity and resistivity of the STO and LNO films when deposited on the silicon substrate. LNO/STO/Si(100) is a suitable conductive substrate for growth of multiferroic functional materials.
Keywords: Perovskite structure, Polycrystalline, Pulsed laser ablation, Buffer layer, Multiferroic, Conductive electrode
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SPECTROPHOTOMETRIC DETERMINATION OF ALUMINIUM USING AURIN TRICARBOXYLIC ACID TRIAMMONIUM SALT IN THE PRESENCE OF CETYLPRIDINIUM CHLORIDE AS SURFACTANT
S.M.H. Bukhari
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A facile, rapid and very sensitive method has been developed for the spectrophotometric determination of aluminum based on complexation reaction between the metal ion and aluminon in the presence of cationic surfactant cetylpyridinium chloride (CPC). The important parameters affecting the analytical procedure were optimized. Absorption maximum for a ternary complex was noted at 535 nm. The reaction was found to be rapid at room temperature and absorbance remained constant for more than one week. The method adheres to Beer’s law in a range of 0.01-0.4 μg mL–1 with apparent molar absorptivity of 8.24×104L mol cm-1 and Sandell’s sensitivity 0.3 ng mL-1. The effect of foreign ions was tested by taking a constant concentration of metal ion and determining its concentration in the presence of ≥ 100 folds in excess of foreign ions. The method has been applied for the determination of aluminum in the pharmaceutical formulations as well as in water samples and a good agreement was found with the values obtained by using FAAS technique. The relative standard deviation was found to be less than 3.5%.
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GEL-COMBUSTION PROCESS FOR SYNTHESIS OF PEROVSKITE OXIDE Sr2FeCoO6
S.K. Durrani
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The ultrafine and well-dispersed strontium iron cobalt based (SrFe0.5Co0.5O3) perovskite oxide powders have been synthesized by nitrate-citrate sol-combustion process with stiochiometeric composition variation of metal nitrate salts and citric acid. Crystallinity and phase analysis were performed by X-ray diffraction (XRD).Inspection of XRD patterns revealed that almost pure single phase SrFe0.5Co0.5O3 cubic Pm3m symmetry was obtained. Morphology of sintered specimens was examined by scanning electron microscopy (SEM). It was observed that grain size of sintered samples increases with calcination temperature. XRD and SEM observations revealed that the crystal formation and morphology of SrFe0.5Co0.5O3 oxide were dependent on the precursors and pH of precursor solutions. The thermal decomposition of gel precursor was investigated by thermogravimetric analysis (TG/DTA).57Fe Mössbauer spectroscopic studies on as-synthesized and calcined specimens have confirmed the uniform dispersion of Fe3+ ions in the tetrahedral framework of SrFe0.5Co0.5O3.
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E-WASTE: AN IMPENDING CHALLENGE
M.D.S. Pirzada
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Driven by the rapidly changing technologies and increasing quantities of end-of-life electronic equipment, electronic waste is emerging as a transnational problem. Industrial nations are shipping millions of obsolete computers yearly to developing countries. The large material flow can be toxic as well as beneficial. This article analyses the flow of obsolete computers to Pakistan and discusses the potential ecological and health impacts of inadequate e-waste management practices. Legislation, regulatory action and public awareness can help avoid the health and environment risks across Pakistan. Adoption of modern recycling technology, on the other hand, can help transform the problem into a multi-million opportunity. However, this requires government support in the form of necessary legislation and strict regulatory actions. Global cooperation – necessary funding and technology transfer – should also be sought.
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COMPARISON OF DIFFERENT METHODS FOR ESTIMATION OF POTENTIAL EVAPOTARNSPIRATION
Muhammad Nazeer
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Evapotranspiration can be estimated with different available methods. The aim of this research study to compare and evaluate the originally measured potential evapotranspirtion from Class A pan with the Hargreaves equation, the Penman equation, the Penman-Montheith equation, and The FAO56 Penman-Monteith equation. The evaporation rate from pan recorded greater than stated methods. For each evapotranspiration method, results were compared against mean monthly potential evapotranspiration (PET) from Pan data according to FAO (ETo=Kpan×Epan), from daily measured recorded data of the twenty five years (1984-2008). On the basis of statistical analysis between the pan data and the FAO56- Penman-Monteith method are not considered to be very significant ( =0.98) at 95% confidence and prediction intervals. All methods required accurate weather data for precise results, for the purpose of this study the past twenty five years data were analyzed and used including maximum and minimum air temperature, relative humidity, wind speed, sunshine duration and rainfall. Based on linear regression analysis results the FAO56 PMM ranked first ( =0.98) followed by Hergreaves method ( =0.96), Penman-Monteith method ( =0.94) and Penman method ( =0.93). Obviously, using FAO56 Penman Monteith method with precise climatic variables for ETo estimation is more reliable than the other alternative methods, Hergreaves method is more simple and rely only on air temperatures data and can be used alternative of FAO56 Penman-Monteith method if other climatic data are missing or unreliable.
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DESCRIPTION OF A NEW CALOGLYPHUS BERLESE MITE (ACARI: ACARIDAE) INFESTING PULSE IN PAKISTAN
M. Sarwar
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Of the 13 new species contained by mite genus Caloglyphus (family Acaridae) found in Pakistan, Caloglyphus arbelos currently collected and identified appears with variable features. The characters of apodeme 3 (ap3) which is reduced and broken medially enable the taxonomic separation of this new species from the other described taxa of genus Caloglyphus recorded in different geographical areas. Some general observations on examination of diagnostic taxonomic features, morphology, drawings and literature survey are given, together including with a short description of habitats in which this species occurs. The concise key only working on hypopus traits usable in taxonomy to discern this species from local and global specimens is made available. These results should help in future mite control efforts because any successful management of pests starts with the correct diagnosis and identification of pest species.
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DETERMINATION OF ATMOSPHERIC 210Pb AND 7Be-LADEN AEROSOLS’ MEAN RESIDENCE TIMES OVER ISLAMABAD.
N. Ali
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The concentrations of 210Pb, 214Pb and 7Be radio-nuclides (having radioactive half lives of 22.3 years, 27 min and 53.29 days, respectively) in 184 surface level air samples of Islamabad (33.38° N, 73.10° E) were measured, using the technique of non-destructive gamma-spectrometry on high purity germanium (HPGe) detector. The mean concentrations of 210Pb, 214Pb and 7Be in the samples were found to be 0.284 ± 0.012 mBq m-3, 631.06 ± 155.47 mBq m-3 and 3.171 ± 0.084 mBq m-3, respectively. The aerodynamic size distribution of 7Be in the atmospheric aerosols were also determined, using an Anderson 1-ACFM cascade impactors, which resulted in the mean diameter of 7Be-laden aerosols as 0.79 ± 0.12 µm. The mean residence times (MRT) for 210Pb and 7Be-laden aerosols, thus obtained, were 5.29 ± 0.91 days and 7.18 ± 0.97 days respectively.
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