Allama Iqbal Open University

Islamabad, Pakistan

Allama Iqbal Open University

Islamabad, Pakistan
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Wong K.M.,Independent Researcher Scientist | Irfan M.,Allama Iqbal Open University | Mahmood A.,King Saud University | Murtaza G.,Islamia College PeshawarKPK
Optik | Year: 2017

Different physical properties of the double perovskite A2InSbO6 (A = Ca, Sr, Ba) compounds are investigated using the full potential linear augmented plane wave method within the density functional theory (DFT) where different generalized gradient approximations are used for approximating the exchange-correlation effects. Importantly, the DFT calculated structural indexes are in close agreement with the experimental data. The compounds show a semiconductor nature with a direct bandgap where the upper valence band is mainly consist of the O-p state, and the lower part of the conduction band is composed of the Sb-s state. Furthermore, the electron charge density plots show that the chemical bonding is partially covalent and ionic. From the DFT calculated optical properties, it is clear that the A2InSbO6 (A = Ca, Sr, Ba) compounds strongly absorb and reflect the incident radiation in the visible and ultraviolet range and can therefore be effectively used in optoelectronic devices. © 2016 Elsevier GmbH

Imran R.M.,University of Aalborg | Hussain D.M.A.,University of Aalborg | Soltani M.,University of Aalborg | Rafaq R.M.,Allama Iqbal Open University
IET Renewable Power Generation | Year: 2017

Multivariable disturbance accommodated observer based control (DOBC) scheme is presented to mitigate loads generated due to wind shear and tower shadow using individual blade pitch for above-rated wind speed condition of wind turbine. Wind shear and tower shadow add flickers as 1p, 3p, 6p and so on, (p is the rotor rotational frequency) for three-bladed wind turbine. Novel DOBC with individual pitch control (IPC) to mitigate the flickers is presented and linear state-space model of wind turbine with tower dynamics is developed. The proposed controller is tuned using optimal control theory to reduce fatigue of drive-train, tower and to regulate output power. The authors have tested the controller on NREL's 5 MW wind turbine, FAST (fatigue, aerodynamics, structures and turbulence) code is used for load modelling and MATLAB/Simulink is used for the simulation. A comparison of power spectral density of generator speed, drive-train torsion and tower fore-aft moment shows better mitigation to the flickers by proposed controller as compared with proportional-integral (PI) and disturbance accommodation control (DAC) with collective pitch control. Furthermore, it shows less degradation in the performance as moving away from the operating point for above-rated wind speed condition of wind turbine. It is concluded that proposed multivariable controller shows better mitigation to turbulent and cyclic aerodynamic loads, provide better regulation to output power using IPC of wind turbine and increased the lifetime of drive-train torsion and tower as compared with PI and DAC. © The Institution of Engineering and Technology 2016.

Saeed S.,Allama Iqbal Open University | Rashid N.,Allama Iqbal Open University | Jones P.G.,TU Braunschweig | Ali M.,University of Punjab | Hussain R.,National Engineering and Scientific Commission
European Journal of Medicinal Chemistry | Year: 2010

Five series of thiourea derivatives bearing benzothiazole moiety (20 compounds) were efficiently synthesized and evaluated for antimicrobial and anticancer activities. The results indicated that the compounds possessed a broad spectrum of activity against the tested microorganisms and showed higher activity against fungi than bacteria. Compounds 1b, 2b, 3b, 4b and 5b exhibited the greatest antimicrobial activity. Preliminary study of the structure-activity relationship revealed that electronic factors in benzothiazole rings had a great effect on the antimicrobial activity of these compounds. In preliminary MTT cytotoxicity studies, the thiourea derivatives (2d, 5c and 5d) were found most potent. In MCF-7 and HeLa cells, the IC 50 values were observed in the range of 18-26 μM and 38-46 μM, respectively. © 2009 Elsevier Masson SAS. All rights reserved.

Saeed S.,Allama Iqbal Open University | Jasinski J.P.,Keene State College | Butcher R.J.,Howard University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

In the title compound, C 13H 9BrN 2O 3, the dihedral angle between the mean planes of the two benzene rings is 3.6 (7)°. The amide group is twisted by 28.1 (6) and 31.8 (3)° from the mean planes of the 4-bromophenyl and 4-nitrobenzene rings, respectively. The crystal packing features weak intermolecular N -H⋯O and C -H⋯O hydrogen bonds resulting in a threedimensional network.

Xavier T.S.,Center for Molecular and Biophysics Research | Rashid N.,Allama Iqbal Open University | Hubert Joe I.,Center for Molecular and Biophysics Research
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

FT-IR and FT-Raman spectra of the 2-(4-Bromophenyl)-1H-benzimidzole were recorded and analyzed in the solid phase. The optimized molecular geometry, the vibrational wavenumbers, the infrared intensities and the Raman scattering activities were calculated by using Hartree-Fock and density functional method (B3LYP) with 6-31G(d,p) basis set. The potential surface scan study was carried out for the conformation of theoretical structure. Detailed interpretation of the vibrational spectra had been carried out with the aid of the normal coordinate analysis. Chemical interpretation of hyperconjugative interaction was done by natural bond orbital analysis. © 2010 Elsevier B.V. All rights reserved.

Ahmad L.,Allama Iqbal Open University | Aslam M.,Forman Christian College | Jun C.-H.,Pohang University of Science and Technology
Transactions of the Institute of Measurement and Control | Year: 2014

A control chart, being an important tool of statistical process control, has been used for process monitoring and detection of any out-of-control process situation. In this paper, the Shewhart X̄ chart, also known as the traditional control chart, in combination with the process capability index Cp proposed by Subramani and Balamurali, is presented under the repetitive sampling scheme. The optimal design parameters of the proposed control chart are calculated. The performance of the proposed control chart is evaluated through the average run lengths (ARLs). Numerical tables have been constructed for the purpose of comparing the in-control ARL and the out-of-control ARL with the single sampling scheme. The findings of the study show that the newly suggested sampling scheme is better than the existing single sampling scheme in detection of mean shift of the process. © The Author(s) 2013.

A series of variously substituted 1,3-thiazole heterocyclic compounds (3a-3d) were prepared by base-catalyzed S-cyclization of corresponding 2,4-dichloro-N-{[(4-substitutedphenyl)amino]carbonothioyl}benzamide (2a-2d) with acetophenone in the presence of bromine. The structure of all compounds was established by IR, 1H-NMR, 13C-NMR, elemental analysis, and X-ray crystallographic analysis. © 2012 Hetero Corporation.

Arif M.,Allama Iqbal Open University | Mahmood K.,University of Punjab
Electronic Library | Year: 2012

Purpose -The aim of this study was to explore the pattern and extent of the adoption of Web 2.0 technologies by Pakistani librarians. Design/methodology/ approach -A survey was conducted using web-based surveying software (SurveyMonkey) and Pakistan based LIS e-mail discussion groups. Professional librarians serving in all types of libraries participated in the study. Findings -Instant messaging, blogs, social networking and wikis were the most popular Web 2.0 technologies. Librarians adopted such technologies in their professional and personal lives. Gender, length of professional experience and place of work have no effect on the frequency of use, while perceived skill level of internet use and perceived ease of Web 2.0 use have a significant effect on the frequency. Lack of computer literacy, and lower availability of computers and internet facilities were the major hindrances of Web 2.0 adoption by librarians. Awareness and training programs could enable librarians to cope with Web 2.0 technologies. Research limitations/implications -Due to the use of a non-probability/non-representative sampling method, the results cannot be generalized. Practical implications -This study will create awareness among LIS professionals toward the use of advanced technology in their professional environment. The findings of this study will contribute to the successful adoption of Web 2.0 in libraries. Originality/value -This is the first study on the adoption of Web 2.0 technologies in Pakistani librarianship. © Emerald Group Publishing Limited.

Arshad N.,Allama Iqbal Open University | Yunus U.,Allama Iqbal Open University | Razzque S.,Allama Iqbal Open University | Khan M.,Allama Iqbal Open University | And 3 more authors.
European Journal of Medicinal Chemistry | Year: 2012

Interaction and binding of isonicotinic acid hydrazide (INH) and its two analogs; pyrazine carboxylic acid hydrazide (PCH) and 2,4-dihydroxy benzoic acid hydrazide (2,4-DHBAH) with DNA has been investigated by UV-spectroscopy and cyclic voltammetry (CV) at physiological conditions of pH and temperature. Experimental results from both techniques were in good agreement and indicated stronger binding and formation of hydrazides-DNA complexes via intercalation. Among three hydrazides, 2,4-DHBAH showed greater interaction toward DNA at stomach pH (4.7) as evident from its comparatively greater binding constant, {K b; 2.02 × 10 4 M -1 (UV), 3.13 × 10 4 M -1 (CV)}. The greater binding site size (n = 3) for 2,4-DHBAH at stomach pH inferred 3:1 binding stoichiometry and possibility of electrostatic interactions or hydrogen bonding along with intercalative mode of interaction between 2,4-DHBAH and DNA. The free energies of hydrazides-DNA complexes indicated the spontaneity of their binding. 2,4-DHBAH has shown promising anti-bacterial activities while anti-oxidant and cytotoxic potentials were exhibited by all three hydrazides. © 2011 Elsevier Masson SAS. All rights reserved.

Arshad N.,Allama Iqbal Open University | Farooqi S.I.,Allama Iqbal Open University | Bhatti M.H.,Allama Iqbal Open University | Saleem S.,Quaid-i-Azam University | Mirza B.,Quaid-i-Azam University
Journal of Photochemistry and Photobiology B: Biology | Year: 2013

A carboxylic acid ligand, (Z)-4-(4-acetylphenylamino)-4-oxobut-2-enoic acid (APA-1), and its triphenyl-(APA-2) and tributyl-tin(IV) (APA-3) compounds have been synthesized and investigated for their binding with ds.DNA using UV-visible spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscosity measurements under physiological conditions of pH and temperature. The experimental results from all techniques i.e. binding constant (Kb), binding site size (n) and free energy change (ΔG) were in good agreement and inferred spontaneous compound-DNA complexes formation via intercalation. Among all the compounds APA-3 showed comparatively greater binding at pH 4.7 as evident from its greater Kb values {APA-3: Kb: 5.63 × 104 M-1 (UV); 7.94 × 104 M -1 (fluorescence); 9.91 × 104 M-1 (CV)}. Electrochemical processes of compounds before and after the addition of DNA were found diffusion controlled. Among all compounds, APA-3 exhibited best antitumor activity. © 2013 Elsevier B.V.

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