| 1. |
- Ilyas, Muhammad Tasaduq, et al.
(författare)
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Substantial performance of copper sulfide nanotubes at high current densities for energy storage applications
- 2024
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Ingår i: Journal of Energy Storage. - : Elsevier. - 2352-152X .- 2352-1538. ; 85
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Tidskriftsartikel (refereegranskat)abstract
- This study presents the direct growth of CuS nanotubes (NTs) on nickel foam using a facile solution synthesis route. The structural, elemental and morphological analyses of CuS NTs grown Ni foam were conducted through X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscope, and field emission scanning electron microscope. The electrochemical performance of the prepared electrodes was comprehensively characterized by cyclic voltammetry (CV), galvanostatic charge discharge and electrochemical impedance spectroscopy. The CuS NTs grown electrodes delivered a specific capacitance of 1539 Fg−1 at 1 mVs−1 and 1365 Fg−1 at 5 Ag−1, demonstrating a remarkable rate capability of 66 % at an extremely high current density of 25 Ag−1. Notably, the CuS NTs electrode demonstrated good cyclic stability, as evidenced by a charge retention of 75.5 % after 3000 cycles at a high current density of 20 Ag−1. The charge storage mechanism was predominantly diffusion controlled, accomplished by analyzing CV data. Overall, this work evinces that the as-synthesized CuS NTs hold a significant promise as electrode materials for high-performance electrochemical energy storage applications.
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| 2. |
- Khan, Muhammad Ahsan Iqbal, et al.
(författare)
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An Experimental and Comparative Performance Evaluation of a Hybrid Photovoltaic-Thermoelectric System
- 2021
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Ingår i: Frontiers in Energy Research. - : FRONTIERS MEDIA SA. - 2296-598X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The majority of incident solar irradiance causes thermalization in photovoltaic (PV) cells, attenuating their efficiency. In order to use solar energy on a large scale and reduce carbon emissions, their efficiency must be enhanced. Effective thermal management can be utilized to generate additional electrical power while simultaneously improving photovoltaic efficiency. In this work, an experimental model of a hybrid photovoltaic-thermoelectric generation (PV-TEG) system is developed. Ten bismuth telluride-based thermoelectric modules are attached to the rear side of a 10 W polycrystalline silicon-based photovoltaic module in order to recover and transform waste thermal energy to usable electrical energy, ultimately cooling the PV cells. The experiment was then carried out for 10 days in Lahore, Pakistan, on both a simple PV module and a hybrid PV-TEG system. The findings revealed that a hybrid system has boosted PV module output power and conversion efficiency. The operating temperature of the PV module in the hybrid system is reduced by 5.5%, from 55 degrees C to 52 degrees C. Due to a drop in temperature and the addition of some recovered energy by thermoelectric modules, the total output power and conversion efficiency of the system increased. The hybrid system's cumulative output power increased by 19% from 8.78 to 10.84 W, compared to the simple PV system. Also, the efficiency of the hybrid PV-TEG system increased from 11.6 to 14%, which is an increase of 17% overall. The results of this research could provide consideration for designing commercial hybrid PV-TEG systems.
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| 3. |
- Latif, Umar, et al.
(författare)
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In situ growth of nickel ammonium phosphate ribbons on nickel foam for supercapacitor applications
- 2023
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Ingår i: Journal of Energy Storage. - : Elsevier. - 2352-152X .- 2352-1538. ; 73:Part B
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Tidskriftsartikel (refereegranskat)abstract
- We report the in-situ growth of the nickel ammonium phosphate (NAP) ribbons on nickel (Ni) foam in a single step process using hydrothermal approach. The morphology, structure and elemental analysis of the NAP-ribbons grown on Ni foam were analyzed by scanning electron microscope (SEM), energy-dispersive x-ray analysis (EDX) and x-ray diffraction. The NAP-coated Ni foam sample was sonicated in ethanol and the obtained suspension was observed through AFM analysis to analyze the lateral dimensions of the NAP-ribbons. The obtained NAP ribbons powder was also characterized by x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Further, the NAP ribbons based electrodes were electrochemically characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge discharge analysis (GCD). NAP ribbons grown on Ni foam as electrodes achieved a specific capacitance (Csp) of 1196 Fg- 1 at 1 mVs- 1 and 1188 Fg- 1 at 1 Ag-1. The charge storage mechanism was identified and quantified by evaluating the CV data in 1-10 mVs- 1 scan rate range. It was established that at low scan rate the charge was dominantly stored by diffusion of electrolyte ions within the gaps of the NAP ribbons resulting in high energy density of 105.5 WhKg-1 at 1 Ag-1. NAP electrodes also demonstrated good cyclic stability by showing 92 % charge retention after 5000 cycles. A symmetric 2-elec-trode device comprised of NAP ribbons electrodes gave Csp of 309 Fg-1 at 1 mVs- 1 with energy density of 42.06 Wh/Kg and power density of 0.5 KW/Kg at 1 A/g current density, which is an exceptional for a symmetric supercapacitor device. The study confirms that NAP ribbons have a promising potential to be employed in the next-generation energy storage devices.
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| 4. |
- Mansha, Saira, et al.
(författare)
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Development of pH-Responsive, Thermosensitive, Antibacterial, and Anticancer CS/PVA/Graphene Blended Hydrogels for Controlled Drug Delivery
- 2024
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Ingår i: Gels. - : MDPI. - 2310-2861. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Drug delivery techniques based on polymers have been investigated for their potential to improve drug solubility, reduce systemic side effects, and controlled and targeted administration at infection site. In this study, we developed a co-polymeric hydrogel composed of graphene sheets (GNS), polyvinyl alcohol (PVA), and chitosan (CS) that is loaded with methotrexate (MTX) for in vitro liver cancer treatment. Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) was employed to check the structural properties and surface morphology. Moreover, tests were conducted on the cytotoxicity, hemolytic activity, release kinetics, swelling behaviour and degradation of hydrogels. A controlled release of drug from hydrogel in PBS at pH 7.4 was examined using release kinetics. Maximal drug release in six hours was 97.34%. The prepared hydrogels did not encourage the HepG2 growth and were non-hemolytic. The current study highlights the potential of GNS-based hydrogel loaded with MTX as an encouraging therapy for hepatocellular carcinoma. HepG2 cell viability of MTX-loaded CS-PVA-GNS hydrogel was (IC50 5.87 mu g/200 mL) in comparison to free MTX (IC50 5.03 mu g/200 mL). These outcomes recommend that hydrogels with GNS ensure improved drug delivery in cancer microenvironment while lessening adverse consequences on healthy cells.
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| 5. |
- Raza, Ahmad, et al.
(författare)
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Spectrum Evaluation in CR-Based Smart Healthcare Systems Using Optimizable Tree Machine Learning Approach
- 2023
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Ingår i: Sensors. - : MDPI Multidisciplinary Digital Publishing Institute. - 1424-3210. ; 23:17
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Tidskriftsartikel (refereegranskat)abstract
- The rapid technological advancements in the current modern world bring the attention of researchers to fast and real-time healthcare and monitoring systems. Smart healthcare is one of the best choices for this purpose, in which different on-body and off-body sensors and devices monitor and share patient data with healthcare personnel and hospitals for quick and real-time decisions about patients' health. Cognitive radio (CR) can be very useful for effective and smart healthcare systems to send and receive patient's health data by exploiting the primary user's (PU) spectrum. In this paper, tree-based algorithms (TBAs) of machine learning (ML) are investigated to evaluate spectrum sensing in CR-based smart healthcare systems. The required data sets for TBAs are created based on the probability of detection (Pd) and probability of false alarm (Pf). These data sets are used to train and test the system by using fine tree, coarse tree, ensemble boosted tree, medium tree, ensemble bagged tree, ensemble RUSBoosted tree, and optimizable tree. Training and testing accuracies of all TBAs are calculated for both simulated and theoretical data sets. The comparison of training and testing accuracies of all classifiers is presented for the different numbers of received signal samples. Results depict that optimizable tree gives the best accuracy results to evaluate the spectrum sensing with minimum classification error (MCE).
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| 6. |
- Raza, Mohsin Ali, et al.
(författare)
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Synthesis and characterization of zinc aluminate electrodes for supercapacitor applications
- 2024
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 475
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Tidskriftsartikel (refereegranskat)abstract
- We report, for the first time, the thorough electrochemical characterization of zinc aluminate spinel. Four different stoichiometric composition of zinc aluminate (ZnAl1.5O3.25, ZnAl2O4, ZnAl2.87O5.30, and ZnAl4O7) were prepared by solution combustion method. The obtained powders after calcination at 1000 °C were characterized through scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction to analyze the morphology, elemental composition and structure, respectively, of the zinc aluminate compositions. The electrodes were prepared by coating slurry of zinc aluminate, carbon black and polyvinylidene fluoride on nickel foam in a ratio of 8:1:1. The electrochemical characterization was carried out by cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). ZnAl1.5O3.25 exhibited the highest specific capacity of 546 C/g at 1 mV/s and 336 C/g at 1 A/g, as appraised by CV and GCD analysis, respectively. EIS test revealed that ZnAl1.5O3.25 had the modest impedance value. The energy density value for ZnAl1.5O3.25 sample was 16.79 Wh/kg at 1 A/g with a power density of 179.9 W/kg. The as developed electrodes showed predominantly pseudo-capacitive charge storage mechanism.
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| 7. |
- Abodayeh, Kamaleldin, et al.
(författare)
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Stochastic Numerical Analysis for Impact of Heavy Alcohol Consumption on Transmission Dynamics of Gonorrhoea Epidemic
- 2020
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Ingår i: Computers, Materials and Continua. - : TECH SCIENCE PRESS. - 1546-2218 .- 1546-2226. ; 62:3, s. 1125-1142
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Tidskriftsartikel (refereegranskat)abstract
- This paper aims to perform a comparison of deterministic and stochastic models. The stochastic modelling is a more realistic way to study the dynamics of gonorrhoea infection as compared to its corresponding deterministic model. Also, the deterministic solution is itself mean of the stochastic solution of the model. For numerical analysis, first, we developed some explicit stochastic methods, but unfortunately, they do not remain consistent in certain situations. Then we proposed an implicitly driven explicit method for stochastic heavy alcohol epidemic model. The proposed method is independent of the choice of parameters and behaves well in all scenarios. So, some theorems and simulations are presented in support of the article.
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| 8. |
- Krämer, Roland, et al.
(författare)
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Degradation of poly (ethylene-co-methacrylic acid)-calcium carbonate nanocomposites
- 2007
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Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 92:10, s. 1795-1802
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Tidskriftsartikel (refereegranskat)abstract
- Composites of poly(ethylene-co-methacrylic acid) with 5 mass fraction percent of precipitated calcium carbonate nanoparticles were prepared by melt extrusion on a miniature melt-blender and medium-scale production equipment. The composites consisted mostly of isolated particles. The ultimate mechanical properties of the nanocomposites were consequently largely superior to composites with micron-sized filler. The calcium carbonate particles were shown to offer a large surface area for calcium salt formation during the thermal degradation of the material. This imparted a stabilizing effect to the copolymer that was comparable to the neutralization of the methacrylic acid units with calcium ions. The rate of calcium salt formation was fast at temperatures above 350 degrees C. Stearic acid surface coatings did not interfere significantly with the calcium salt formation. The oxidative stability of the composites was further largely improved by the formation of a diffusion barrier.
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| 9. |
- Shatanawi, Wasfi, et al.
(författare)
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Essential Features Preserving Dynamics of Stochastic Dengue Model
- 2021
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Ingår i: CMES - Computer Modeling in Engineering & Sciences. - : TECH SCIENCE PRESS. - 1526-1492 .- 1526-1506. ; 126:1, s. 201-215
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Tidskriftsartikel (refereegranskat)abstract
- Nonlinear stochastic modelling plays an important character in the different fields of sciences such as environmental, material, engineering, chemistry, physics, biomedical engineering, and many more. In the current study, we studied the computational dynamics of the stochastic dengue model with the real material of the model. Positivity, boundedness, and dynamical consistency are essential features of stochastic modelling. Our focus is to design the computational method which preserves essential features of the model. The stochastic non-standard finite difference technique is most efficient as compared to other techniques used in literature. Analysis and comparison were explored in favour of convergence. Also, we address the comparison between the stochastic and deterministic models.
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