COMSATS University Islamabad
  • Islamabad, Capital, Pakistan
Recent publications
Purpose: The aim of this study was to assess the antibacterial potential and ex vivo skin permeation kinetics of cefixime from bionanocomposite films. Methods: The films were prepared by solvent casting method by using chitosan and starch. The fabricated films were tested for their antibacterial potential against three bacteria i.e. Escherichia coli, Klebsiella pneumonia, and Acetobacter aceti. In vitro permeation studies of cefixime from the films across rat skin was conducted using Franz diffusion cell. Results: The highest antibacterial effect was exhibited by F5 formulation (non-irradiated film) against Escherichia coli and Klebsiella pneumonia; however, antibacterial activity of the films was significantly (p < 0.05) reduced after their irradiation. F5 formulation showed the highest cumulative amount of permeated drug after 24 h, while F1 (100% chitosan) showed the lowest amount of permeated drug. Non-Fickian diffusion (anomalous) was the main mode of drug release from all films. The cross-linking of films by γ-radiations improved their mechanical properties. The percentage swelling ratio was the highest in non-irradiated films having a polymeric blend (50:50). Water uptake of irradiated films was appreciably reduced as compared to non-irradiated films. Conclusion: The synthesized bionanocomposites are promising therapeutic moieties which not only improve drug permeability across but also ameliorates antibacterial potential of cefixime.
Nanofluid consideration has been magnified due to their exceptional heat transfer characteristics and prospective applications in engineering and medical sciences after the pioneering work of Choi. Since, majority fluids are non-Newtonian in nature. Therefore, considering Jeffrey fluid as a base fluid in current study enhance its role in applications. Moreover, geometric configuration of the channel is taken as asymmetric with tapering effects. Since, majority of human physiological systems and industrial machinery have complex geometry and. Therefore, tapering channel consideration cannot be ignored. High molecular weight of non-Newtonian liquids make no-slip condition inapplicable. Thus, slip effects are incorporated in the current analysis. The consider analysis is performed for peristaltic flow of Jeffrey Nano fluid through a tapered asymmetric channel in the presence of magnetic field. Main motivation for performing this study is to analyze the heat transfer properties of nanofluid for the treatment of multiple diseases like cancer. The resulting nonlinear equations are coupled and simplified through lubrication approach. Poisson-Boltzmann equations are linearized through Debye-Huckle linearization. Built-in command of NDSolve in MATHEMATICS is applied to compute the results. The results for velocity, pressure gradient, streamlines, temperature and concentration are discussed for involved parameters. The results indicate that velocity shows parabolic behavior near the center while mixed behavior is observed near the boundaries. It can also be noticed that tapering parameter (m) influence the velocity greatly. As increasing the tapering effect causes the geometry to expand resulting in decreased velocity near the center of the channel. During digestion of food, multiple chemical reactions are performed by enzymes, therefore, studying the impact of (γ) on temperature and concentration cannot be ignored. The outcome of the study shows decrease in temperature and concentration as energy is utilized in performing the digestion. The size of trapped bolus is found to be increasing as the values of Hartman number (M) and fluid parameter (λ1) are increased. Therefore, we can say that this study can provide basics to study physiological system with electroosmotic phenomenon. It also finds promising applications in drug delivery and food diagnostic etc.
Automated formulation of sketches from face photos has seen successive growth since the work of Wang and Tang in recent years. Each new methodology is, however, able to partially achieve its objective of sketch synthesis while using pairs of photos and viewed sketches as a training medium. The viewed sketches are also used as a testing medium to determine the success of those methodologies. Resulting sketches do not fully capture all features of the training photos and viewed sketches. Their similarity value to respective sketch is also around 30 – 50%. One technique may produce sketches with sharp edges, but they do not bear completeness of facial features. Another technique produces sketches with the completeness of facial elements, but they are not well-focused. Second limitation of existing techniques is attributable to face-recognition procedure which is used as a validation step for these methodologies. Face-recognition process with help of synthesized sketches delivers reliable results over datasets with a limited diversity of age, ethnicity, and light intensities. We propose a novel and cost-effective approach to fuse resulting sketches of two test techniques. The two techniques are merged to yield a better sketch containing well-defined features, sharp contours, and less noise. Secondly, fusion suppresses limitations of the component methodologies reaching the resulting sketch. To test this idea of combining sketch-synthesis methods, we experiment with the most basic techniques of image fusion including simple (arithmetic), PCA, and Wavelet based fusions. The proposed setup considered FCN (complete features but less sharpness) and Fast-RSLCR (sharp edges but missing contours) as candidate techniques. It is tested on two datasets namely CUFS and CUFSF. Second dataset incorporates variations of age, ethnicity, light intensities, and slightly deformed features between photos and viewed sketches. Our results indicate achievement of 60.29% SSIM score (enhancement by 3.84%) and 79.03% face-recognition score (enhancement by 5.62%) as compared to Fast-RSLCR.
In this article, the problem of fault estimation is addressed for the class of discrete-time linear systems subject to mixed uncertainties (norm bounded and stochastic uncertainty) and unknown input disturbances. A robust proportional integral (PI) observer is proposed based on H∞ norm minimization for dealing with uncertainties and disturbances. An augmented observer is constructed first where the sensor fault is treated as a state variable and then, H∞ norm is minimized in the linear matrix inequalities (LMI) framework with the application of the Lyapunov function and Young inequalities. The application of the DC motor system and well-known three tank system is given to demonstrate the performance of the proposed observer. Through simulation results, a proposed PI observer has shown the precise estimation of a sensor fault.
In this paper, we investigate new classes of general quasi-variational inclusions. In this regard, we prove that general quasi-variational inclusions and fixed point problems are equivalent. This equivalence is useful in the study on the existence of a solution as well as to propose some iterative methods. Moreover, under suitable conditions, we formulate and prove some convergence results. The main results derived in this paper continue to be true for quasi-variational and variational inequalities, or related problems, since the general quasi-variational inclusions include these problems.
In this work, the influence of thermal energy in term of heat source, thermal radiation and chemical reaction on magneto hydrodynamic Casson fluid flow model (MHD-CFM) over a nonlinear slanted extending surface with slip velocity in a Forchheimer permeable medium is numerically studied using the Levenberg Marquardt methodology with backpropagated learning mechanism. It is valuable to evaluate the flow of Cason fluids based on materials (such as drilling muds, clay coatings, various suspensions and certain lubricating oils, polymeric melts, and a wide range of colloids) in the occurrence of heat transfer. Using efficient data, PDEs of (MHD-CFM) were converted to ordinary differential equations. These obtained non-linear ODEs are then rectified using the computational power of the Lobatto IIIA approach to obtain a dataset of Levenberg Marquardt algorithm based trained neural networks (LMA-TNN) for six scenarios of this presented model, which were graphically represented using nftool to obtain regression, efficiency, fit curve, error bars, and trained state analysis. The velocity, temperature, and concentration profiles were computed, and the findings were presented. Additionally, the skin friction coefficient, Nusselt number, & local Sherwood number are explored. The graphs show that when values of radiation parameter and the Forchheimer porous media parameter increase, the temperature of the plate drops. In the existence of a chemical process and a high Schmidt number, the concentration drops. The accuracy achieved in terms of relative error demonstrates the validity and significance of the solution process. Ó 2022 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University This is an open access article under the CC BY license
The flow under an Eyring-Powell description has attracted interest to model different scenarios related with non-Newtonian fluids. The goal of the present study is to provide analysis of solutions to a one-dimensional Eyring-Powell fluid in Magnetohydrodynamics (MHD) with general initial conditions. Firstly, regularity and bounds of solutions are shown as a baseline to support the construction of existence and uniqueness results. The existence analysis is based on the definition of a Hamiltonian that constitutes the underlying theory to obtain stationary profiles of solutions that are validated with a numerical approach. Afterwards, non-stationary profiles of solutions are explored based on an asymptotic approximation to a Hamilton-Jacobi type of equation. To this end, an exponential scaling is considered together with perturbation methods. Finally, a region of validity for such exponential scaling is provided.
This study investigates the effect of self-expressiveness and hedonic brand aspect on brand jealousy through brand love of female fashion clothing brands. Conceptualized research framework is empirically tested through utilization of Smart PLS. Data are collected through questionnaire survey from 313 female consumers of fashion clothing brand with convenience sampling. It is empirically proven that self-expressiveness and hedonic brand aspect are positively related with brand love and indirectly associated with brand jealousy for female fashion clothing brands. Brand love in association with brand jealousy enhances knowledge in the context of female fashion clothing brands.
This research demonstrates first report on successful formation of ZnSe/amino functionalized graphene quantum dots (af-GQDs), type-II core-shell structures. The structures having potential as a single emissive layer (SEL), were synthesized via a facile and eco-friendly hot injection method. We achieved a highly efficient tuning of PL emission spectral components in visible region ranging from (∼458 to 750nm). The functional groups attached with af-GQDs rendered soft shell feature to the structures and the soft core-shell interface significantly passivated the strain-induced defect states and reduced Auger recombination (AR). The PL emission properties of ZnSe/af-GQDs were studied through steady state and temperature dependent photoluminescence (TDPL) spectroscopy within the temperature range (80-300k), using 457nm excitation laser. Three samples including bare ZnSe QDs, bare af-GQDs and ZnSe/af-GQDs core/shell structures were prepared. The steady state PL emission spectra revealed a weak blue and pronounced green, yellow, orange and red emission, whereas the full width half maximum (FWHM) of PL spectra distinctly decreased in ZnSe/af-GQDs. The carrier activation and escape energies of radiative and non-radiative recombination respectively were estimated through Arhenious and Brethelot fitting functions for TDPL measurements. The calculated values clearly indicated a decrease in activation energies and an increase in escape energies in ZnSe/af-GQD X-ray photon spectroscopy (XPS) measurements revealed the presence of Zn 2p and Se (3d) O1s and NIs orbitals of constituent elements including Zn, Se, C, O and N. Tight binding model was applied to estimate the valance and conduction band energies that suggested formation of type-II core-shell band alignment in the structures. The relative PLQY was estimated using comparative method and Rhodamine-B was used as reference and calculated PLQY are 58%, 61% and 83% for ZnSe, af-GQDs and ZnSe/af-GQDs. A mechanism of formation of a soft core-shell interface for ZnSe/af-GQDs is clarified. We suggest that ZnSe-/af-GQDs structures synthesized in this report have a great potential for LEDs and display devices in which multi-color components are of paramount importance, such as white light emission. This report may open a gate way for more and vivid possibilities to apply af-GQDs for optoelectronic devices.
The subject of an optimal control of distributed generation (DG) units in AC islanded microgrid (IMG) has gain an important research attention in a recent time. Such control method promises voltage regulation and resolve inaccuracy of power sharing caused by high loads and line differences in a droop-controlled IMG. This research work proposes a multi-objective optimization droop control strategy, where three objective functions corresponding to: (i) load-bus voltage regulation; (ii) accurate real power sharing; and (iii) reactive power sharing, are constructed to improve the system performance and stability in IMG. The numerical approximation method through Lagrange multiplier is employed, subject to equality constraint function. An important aspect of proposed solving algorithm related to objective function is the voltage magnitude information only required to be transferred to each inverter's local voltage controller. Further, a supervisory secondary control layer is used to regulate the system frequency deviations. The results obtained from MATLAB/Simulink and experiment show the effectiveness for optimizing the reactive power injected by each DG unit and load-bus-voltage, under series of parameters uncertainties. Modeling and analysis are investigated through improved mathematical small signal models.
In this article, the peristaltic flow of blood-based nanofluid is examined numerically by employing the generalized differential quadrature method. The Casson constitutive model is adopted to depict the flow characteristics in a uniform wavy tube. Besides, the non-Newtonian nature and heat transfer feature of the nanofluidic medium are also scrutinized properly in the presence of platelet magnetite nanoparticles Fe3O4. After deriving the governing conservation equations, the resulting flow model is modeled successfully under the realistic assumptions of long wavelength and low Reynolds number. Also, the experimentally tested correlations related to the thermophysical properties of nanofluids are incorporated in the conservation equations to explore the effect of adding magnetite nanoparticles in the biofluidic medium. Mathematically, the obtained partial differential equations are transformed into the dimensionless form by utilizing feasible transformations. Furthermore, the impacts of sundry physical parameters on the trapping phenomena, pressure gradient, velocity, wall shear stress, and temperature are discussed thoroughly for the present MHD non-Newtonian nanofluid flow model via various displays.
Flux switching motor (FSM) with field excitation is permanent magnet free and attractive for many industrial and domestic applications. However, design with the conventional trapezoidal stator slot has low efficiency and always been a challenge in the state of the art. Further, the finite element analysis (FEA) method for the electromagnetic performance investigation is a powerful tool, but, it has high computational time, computational complexity and drive storage. To address the concern of low efficiency, in this paper, a new single phase 8slots–6poles electrically excited (EE) FSM design with the rectangular stator slot (RSS), salient rotor and non-overlapped windings for pedestal fan applications is been proposed. The proposed RSS EEFSM design is analyzed analytically and the analytical results are validated by FEA method. Finally, experimental test of the proposed EEFSM prototype is performed. The measured results are in a good agreement with the calculated results. Moreover, the proposed RSS EEFSM has higher efficiency as compared to the conventional design.
Reflection, transmission as well as absorption coefficients and the corresponding Goos Hänchen shift in reflection and transmission is controlled and modified under the effects of Kerr nonlinearity, Doppler broadening as well as Compton scattering. The summation of the absolute values of these coefficients gives a unit value in the presence of all these effects. Modification of the coefficients follows the normalization condition. Maximum GH-shift in the reflection/transmission is investigated to ±3λ. Above ϕc=π/6, the GH-shift is saturated at the value λ in both reflection/transmission. The positive as well as negative GH-shift is measured in the absence and presence of Compton scattered reflected/transmitted beam. The GH-shift is the function of control fields, Kerr nonlinearity, incoherent effect of Doppler broadening and incident as well as the Compton scattered angles. The results show potential applications in nano-optics, trapping of optical data, micro-optics, acoustics, sensor technology and plasma physics.
This study proposes and tests a typology of domain knowledge and team creativity by empirically assessing the effects of varying levels of domain knowledge on the creative outcomes of the team members. Two separate studies were conducted to address this inquiry. Study one aimed at determining the level of domain knowledge of each team member in the teams. Eleven groups comprising of thirty-three business students designed eleven advertisements for the products of their own choices. Utilizing the situation judgment test and the grade earned in the advertising course, four teams were formed comprising two balanced and two imbalanced domain knowledge teams. To test the hypotheses of the study, these teams were asked to develop a print advertisement for Nescafe for the summer season (Study Two). Upon creativity assessment of the final ads by twenty-six independent creative personnel in a total of seven advertising agencies in Pakistan, the results revealed that a balanced team with low domain knowledge outperformed the other balanced team with high domain knowledge. Further, unexpectedly, one of the imbalanced domain knowledge teams also outperformed the balanced high domain knowledge team. The study in the light of extant literature presents worthwhile implications for academia and practitioners.
Herein, catalytic effects of Zn and Mo-loaded HZSM-5 on pyrolysis of food waste (FW) under methane (CH4) and a hydrogen (H2)-rich gas stream derived from catalytic CH4 decomposition (CH4-D) over a Ni–La2O3–CeO2/Al2O3 were explored as a method to produce high-value biochemicals such as benzene, toluene, ethylbenzene, and xylenes (BTEX). The CH4-D pyrolysis medium led to a higher BTEX yield than a typical pyrolysis medium (e.g., nitrogen) and CH4 medium because it provided a H2-rich environment during the FW pyrolysis (e.g., H2/CO2 ratio = 1.01), thereby facilitating hydropyrolysis and hydrodeoxygenation of pyrolytic vapors evolved from FW. The H2-rich environment also helped to reduce coke deposition on the catalyst. Under CH4-D environment, a bimetallic Zn–Mo catalyst supported on HZSM-5 (Zn–Mo/HZSM-5) maximized the BTEX yield (19.93 wt.%) compared to HZSM-5 and monometallic Zn and Mo catalysts. This is most likely because the bimetallic catalyst possessed the highest number of total acid sites among all the tested catalysts. The high acidity and H2-rich media (CH4-D) synergistically promoted aromatization, hydrodeoxygenation, and hydrodealkylation reactions, which enhanced the BTEX yield. The Zn–Mo/HZSM-5-catalyzed FW pyrolysis under CH4-D environment would be an eco-friendly and sustainable strategy to transform unmanageable organic waste (e.g., FW) into high-value biochemicals such as bioaromatics.
Nanofluids are quite popular among researchers due to their high heat transfer rates, which have significant industrial applications. The primary objective of this article is to give a novel analysis of the two-dimensional electromagnetohydrodynamic (EMHD) stagnation point flow of Casson nanofluid with heat source/sink and thermal radiations. Nanoparticles such as Iron Oxide (Fe2O3) and Gold (Au)) are used with blood as base fluid. Nanomaterials are classified into several categories based on their shapes, properties, and sizes. The effects of shape factors namely sphere, tetrahedron, hexahedron, column, and lamina with various parameters are also included in this analysis. This study presents the implementation of single-phase (Tiwari-Das) model for Casson nanofluid by considering blood as base fluid. Instead of the Buongiorno model, which largely depends on Brownian and thermophoresis diffusion effects for heat transfer analysis. The single-phase model incorporates the volume fraction of nanoparticles for the evaluation of heat transfer. Relying on the Tiwari–Das model for nanofluids, a mathematical framework is constructed. To simplify the governing flow equations, proper nonsimilar conversions are used to appropriately transform the given partial differential system to dimensionless form. The rehabilitated mathematical model is simulated by employing local non-similarity technique via bvp4c. The consequences of sundry parameters against velocity and temperature profiles of Casson nanofluid are presented pictorially. The velocity profile is observed to decrease with increasing Casson fluid parameter values while enhancement is noticed with rising electric field parameter values. The temperature profile improves with increasing magnetic number, nanoparticle concentration, Eckert number, Biot number, and heat generation parameter, whereas it degrades with increasing electric field parameter. Temperature profile is maximum for lamina shaped particle while it has minimum values for sphere shape nanoparticles. The Nusselt number and skin-friction coefficients are also introduced as tools for determining the physical characteristics of Casson nanofluid flow. The obtained results of this model meticulously match those existents in the literature for various limiting constraints. The authors discussed the local non-similarity technique for simulating the dimensionless non-similar structure. To the best of authors observations, no such study for the considered flow model is yet published in literature.
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6,306 members
Mahnaz Qader Haseeb
  • Department of Physics
Faheem Shah
  • Department of Chemistry
Wajahat Mahmood Qazi
  • Department of Computer Sciences
Arfat Yameen
  • Department of Pharmaceutical Sciences
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