Peshāwar, Pakistan
Peshāwar, Pakistan

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Manan A.,University of Science & Technology Bannu | Ali R.,University of Science & Technology Bannu | Ahmad A.S.,Islamia College Peshawar
Journal of Materials Science: Materials in Electronics | Year: 2017

Ca substituted Sr5Ta4TiO17 ceramics were fabricated via solid state mixed oxide route. For all the investigated compositions, single phase was obtained. All the investigated ceramics crystallized into an orthorhombic crystal structure with space group Pnnm. Sr5Ta4TiO17 exhibited lower τf (~180 ppm/°C) and higher Qufo (~8500 GHz) than its Nb analog compound (Sr5Nb4TiO17). The Ca substitution for Sr tuned the τf of Sr5Ta4TiO17 ceramics through zero and enhanced the Qufo value at the cost of a decrease in εr value. A good combination of microwave dielectric properties i.e. εr ~49, Qufo ~13560 GHz and τf ~−9 ppm/°C was achieved for SrCa4Ta4TiO17 ceramics sintered at 1575 °C for 4 h respectively. © 2017 Springer Science+Business Media New York


Ullah M.,Islamia College Peshawar | Murtaza G.,Islamia College Peshawar | Ramay S.M.,King Saud University | Mahmood A.,King Saud University
Materials Research Bulletin | Year: 2017

Magnesium pnictides Mg3X2 (X = N, P, As, Sb, Bi) have gained importance due to their fascinating physical properties. These compounds have been mainly studied from the structural and electronic band structure aspects. In this work, the structural, electronic, optical and thermoelectric properties of Mg3X2 (X = N, P, As, Sb, Bi) compounds have been investigated by using density functional theory. The crystal structure of the compounds is optimized through Wu-Cohen generalized gradient approximation (WC-GGA). Modified Becke-Johnson exchange potential predicted the bandgaps larger than the WC-GGA and Englo-Vosko GGA. All the compounds are predicted to be direct bandgap. Bandgap of the compounds decreased by changing the cation from N to Bi. Optical properties of the compounds are described in details. The thermoelectric properties of the compounds are also characterized. On the basis of suitable direct bandgap nature and good thermoelectric coefficients these materials are potential candidates for the optoelectronics and thermoelectric applications. © 2017 Elsevier Ltd


Ahmad S.,Islamia College Peshawar | Iqbal Y.,University of Peshawar | Muhammad R.,Abdul Wali Khan University Mardan
Boletin de la Sociedad Espanola de Ceramica y Vidrio | Year: 2017

The use of by-products as additives in brick industry is gaining increased research attention due to their effective role in decreasing the total energy needs of industrial furnaces. In addition, these additives leave pores upon burning, causing a decrease in thermal conductivity and affect the mechanical properties of bricks as well. In the present study, various proportions of coal and wheat husk were used as additives in the initial ingredients of clay bricks. Microstructure, thermal conductivity, coefficient of thermal diffusivity, water absorption, shrinkage, compressive strength and bulk density of fired clay bricks with and without additives were investigated. Clay bricks containing 5-15. wt.% additives were found to be within the permissible limits for most of the recommended standard specifications. © 2017 SECV.


Khan Z.H.,Peking University | Khan W.A.,National University of Sciences and Technology | Qasim M.,COMSATS Institute of Information Technology | Shah I.A.,Islamia College Peshawar
IEEE Transactions on Nanotechnology | Year: 2014

This paper investigates stagnation point flow and heat transfer of a ferrofluid toward a stretching sheet in the presence of viscous dissipation. Three types of ferroparticles: magnetite (Fe3O4 ), cobalt ferrite (CoFe24), and Mn-Zn ferrite (Mn-ZnFe2O 4) are considered with water and kerosene as conventional base fluids. Numerical solutions to the resulting ordinary differential equations are obtained by using an implicit finite-difference method with quasi-linearization technique. The effects of controlling parameters on the dimensionless velocity, temperature, skin friction, and Nusselt numbers are investigated. It is found that kerosene-based ferrofluids have higher skin friction and Nusselt numbers than water-based ferrofluids. The numerical results of skin friction are compared with the available data for special cases and are found to be in good agreement. © 2002-2012 IEEE.


Barkatullah,Islamia College Peshawar | Ahmad I.,Bacha Khan University | Ibrar M.,University of Peshawar | Jelani G.,University of Peshawar
Pakistan Journal of Botany | Year: 2015

Sapindus mukorossi Gaertn, locally named as soap nut tree is a deciduous plant reaching up to the 20 m height. Present study is designed to investigate allelopathic potential of S. mukorusii through its aqueous extracts against Pennisetum americanum (L.) K. Schum., Setaria italica (L.) P. Beauv. and Lactuca sativa L. The effect of aqueous extracts of leaves and fruits in different concentration (5%, 10%), hot water extracts, soil intoxication and litter was observed on germination, fresh and dry weight, moisture content and overall growth of test species. Plant extracts significantly inhibit germination rate and overall growth of all the test species. Activity of extract were found dependent on concentration and soaking duration of extract, thus highest activities were recorded for extracts with 10% concentration with 72 hours soaking duration. L. sativa was found most susceptible in regard of germination. Plumule length of S. italica was most inhibited. The effect of both cold and hot water extracts showed maximum activities against the radicle lengths of S. italiccertaina and P. americanum while L. sativa was found least susceptible. Soil intoxication and letter showed maximum inhibitory activity against the L. sativa. The study thus reveals that the S. mukorusii is significantly allelopathic to towards the test species and inhibits both their germination and overall growth. © 2015, Pakistan Botanical Society. All rights reserved.


Siddiqui I.,Graz University of Technology | Siddiqui I.,University of Karachi | Khan S.,Graz University of Technology | Khan S.,Islamia College Peshawar | Windholz L.,Graz University of Technology
European Physical Journal D | Year: 2014

We present 66 even and 58 odd parity newly discovered fine structure levels of Pr I with high angular momentum: J = 15/2, 17/2 and 19/2 and 21/2. Spectral lines in the range 4200 Å to 7500 Å were experimentally investigated using laser induced fluorescence spectroscopy in a hollow cathode discharge lamp. The levels were discovered by analysis of the recorded hyperfine patterns of the investigated transitions. More than 800 spectral lines could be classified with help of these levels. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.


Rahman M.-U.,Islamia College Peshawar | Nabi J.-U.,Ghulam Ishaq Khan Institute of Engineering Sciences and Technology
Astrophysics and Space Science | Year: 2013

The Gamow-Teller strength distribution function, B(GT), for the odd Z parent 51V, N-Z=5, up to 30 MeV of excitation energy in the daughter 51Ti is calculated in the domain of proton-neutron Quasiparticle Random Phase Approximation (pn-QRPA) theory. The pn-QRPA results are compared against other theoretical calculations, (n, p) and high resolution (d, 2He) reaction experiments. For the case of (d, 2He) reaction the calibration was performed for 0≤E j≤5.0 MeV, where the authors stressed that within this excitation energy range the ΔL=0 transition strength can be extracted with high accuracy for 51V. Within this energy range the current pn-QRPA total B(GT) strength 0.79 is in good agreement with the (d, 2He) experiment's total strength of 0.9±0.1. The pn-QRPA calculated Gamow-Teller centroid at 4.20 MeV in daughter 51Ti is also in good agreement with high resolution (d, 2He) experiment which placed the Gamow-Teller centroid at 4.1±0.4 MeV in daughter 51Ti. The low energy detailed Gamow-Teller structure and Gamow-Teller centroid play a sumptuous role in associated weak decay rates and consequently affect the stellar dynamics. The stellar weak rates are sensitive to the location and structure of these low-lying states in daughter 51Ti. The calculated electron capture rates on 51V in stellar matter are also in good agreement with the large scale shell model rates. © 2013 Springer Science+Business Media Dordrecht.


Rahman M.-U.,Islamia College Peshawar | Nabi J.-U.,Ghulam Ishaq Khan Institute of Engineering Sciences and Technology
Astrophysics and Space Science | Year: 2014

The Gamow-Teller (GT) transitions within massive stars play sumptuous role in the dynamics of core collapse supernovae. GT strength distributions and electron capture rates have been calculated for odd-A nucleus 59Co within the proton-neutron quasiparticles random phase approximation (pn-QRPA) formalism. The pn-QRPA results are compared with other model calculations and (n,p) reaction experiment carried out at TRIUMF charge-exchange facility. The pn-QRPA calculated a total B(GT +) strength of 3.3 for 59Co to be compared with the shell model value of 2.5 and the 1.9±0.1 in the (n,p) charge-exchange reaction. Aufderheide et al. (1993) extracted total strength equaling 2.4±0.3. The placement of GT centroid at 5.6 MeV by the pn-QRPA model is in reasonable agreement with the shell model centroid at 5.1 MeV whereas the measured GT centroid was placed at 4.4±0.3 MeV in the (n,p) experiment. Fuller, Fowler and Newman (FFN) (1980, 1982a, 1982b), placed the GT centroid at too low excitation energy of 2.0 MeV in the daughter nucleus 59Fe, and this misplacement led to the enhancement of FFN rates. The suppressed pn-QRPA and shell model electron capture rates are in good agreement with each other. The rates are suggestive of higher value of Ye (electron-to-baryon ratio) and may contribute to a more massive homologously collapsing core resulting in a more energetic shock. It might be interesting for the simulators to check the effect of these suppressed rates on the fine-tuning of the time rate of Ye, the concomitant heavy element nucleosynthesis, and, on the energetics of the subsequent shock wave. © 2014 Springer Science+Business Media Dordrecht.


Muhammad K.,Sejong University | Sajjad M.,Islamia College Peshawar | Baik S.W.,Sejong University
Journal of Medical Systems | Year: 2016

In this paper, the problem of secure transmission of sensitive contents over the public network Internet is addressed by proposing a novel data hiding method in encrypted images with dual-level security. The secret information is divided into three blocks using a specific pattern, followed by an encryption mechanism based on the three-level encryption algorithm (TLEA). The input image is scrambled using a secret key, and the encrypted sub-message blocks are then embedded in the scrambled image by cyclic18 least significant bit (LSB) substitution method, utilizing LSBs and intermediate LSB planes. Furthermore, the cover image and its planes are rotated at different angles using a secret key prior to embedding, deceiving the attacker during data extraction. The usage of message blocks division, TLEA, image scrambling, and the cyclic18 LSB method results in an advanced security system, maintaining the visual transparency of resultant images and increasing the security of embedded data. In addition, employing various secret keys for image scrambling, data encryption, and data hiding using the cyclic18 LSB method makes the data recovery comparatively more challenging for attackers. Experimental results not only validate the effectiveness of the proposed framework in terms of visual quality and security compared to other state-of-the-art methods, but also suggest its feasibility for secure transmission of diagnostically important keyframes to healthcare centers and gastroenterologists during wireless capsule endoscopy. © 2016, Springer Science+Business Media New York.


Yousaf M.,University of Technology Malaysia | Inam F.,Lahore University of Management Sciences | Khenata R.,University of Mascara | Murtaza G.,Islamia College Peshawar | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

First principle calculations are carried out to study the effect of pressure (up to 30 GPa) on physical properties of HgIn2S4 and ZnIn2S4 thiospinels. A number of structural, electronic and optical parameters are calculated, and equations are developed for their prediction at different pressures. Highly effective all electron FP-LAPW+lo method coupled with two different approximations (GGA+U and mBJ-GGA) provides very accurate results. All relationships developed between pressure and structural parameters are in full accordance with the established theory thus validating the approach used in the current study. Computed In-S bond length for ZnIn2S4 matches closely with the experimental value. The band gap values of 0.920 eV (1.851 eV) and 1.68 eV (2.733 eV) are obtained with GGA+U (mBJ-GGA) at 0 GPa for HgIn2S4 and ZnIn 2S4, respectively. Additionally, we have calculated the optical properties, namely, the complex dielectric function, refractive index, extinction coefficient, reflectivity, optical conductivity, absorption coefficient and electron energy loss function under pressure effect for radiation up to 30.0 eV. The first critical point also known as optical's absorption edge calculated with GGA+U (mBJ-GGA) appears at 0.939 eV (1.891 eV) and 1.701 eV (2.981 eV) for HgIn2S4 and ZnIn 2S4, respectively. Variation of the absorption spectrum indicates the prospective use of both compounds for device applications, which can be operated on a wide range of the energy scale. The entire work gives useful results of fundamental importance, which can be utilized for the fabrication of optoelectronic devices. © 2013 Elsevier B.V. All rights reserved.

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