| 1. |
- Batool, Javaria, et al.
(författare)
-
Oxygen-vacancy-induced magnetism in anti-perovskite topological Dirac semimetal Ba3SnO
- 2021
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 23:43, s. 24878-24891
-
Tidskriftsartikel (refereegranskat)abstract
- The thermodynamic, structural, magnetic and electronic properties of the pristine and intrinsic vacancy-defect-containing topological Dirac semimetal Ba3SnO are studied using first-principles density functional theory calculations. The thermodynamic stability of Ba3SnO has been evaluated with reference to its competing binary phases Ba2Sn, BaSn and BaO. Subsequently, valid limits of the atomic chemical potentials derived from the thermodynamic stability were used for assessing the formation of Ba, Sn and O vacancy defects in Ba3SnO under different synthesis environments. Based on the calculated defect-formation energies, we find that the charge-neutral oxygen vacancies are the most favourable type of vacancy defect under most chemical environments. The calculated electronic properties of pristine Ba3SnO show that inclusion of spin–orbit coupling in exchange–correlation potentials computed using generalized gradient approximation yields a semimetallic band structure exhibiting twin Dirac cones along the Γ–X path of the Brillouin zone. The effect of spin–polarization and spin–orbit coupling on the physical properties of intrinsic vacancy defects containing Ba3SnO has been examined in detail. Using Bader charges, electron localization function (ELF), electronic density of states (DOS) and spin density, we show that the isolated oxygen vacancy is a magnetic defect in anti-perovskite Ba3SnO. Our results show that the origin of magnetism in Ba3SnO is the accumulation of unpaired charges at the oxygen vacancy sites, which couple strongly with the 5d states of the Ba atom. Owing to the metastability observed in earlier theoretically predicted magnetic topological semimetals, the present study reveals the important role of intrinsic vacancy defects in giving rise to magnetism and also provides opportunities for engineering the electronic structure of a Dirac semimetal.
|
|
| 2. |
- Muzaffar, Nimra, et al.
(författare)
-
Designing of VCuS@MXene nanocomposite electrode for energy storage device and electrochemical glucose sensor
- 2024
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Nature. - 0957-4522 .- 1573-482X. ; 35:9
-
Tidskriftsartikel (refereegranskat)abstract
- MXene, a two-dimensional (2D) material composed of transition metal carbides (TMCs) and nitrides, have fascinated substantial scientific interest. This increased interest results from their exceptional properties, which include extraordinary conductivity, transparency, outstanding absorbing capacity, and significant charge storage capacities. In this work, the MXene-doped vanadium copper sulfide (VCuS) was synthesized through the hydrothermal method. In three electrode measurement system, the VCuS/MXene composite electrode showed exhibited a specific capacity (Qs) of 1620 Cg−1. As application point of view, the hybrid device is designed and measured the electrochemical properties. The hybrid device showed the remarkable Qs of 1528 C.g−1, power density (Pd) of 2347 Wkg−1 and an energy density (Ed) of 34.99 Whkg−1. Further, the VCuS/MXene//AC device is measured up to 6000 cycles to check the stability and durability. The device showed the capacity retention (CR) of 88.5% and a high Coulombic efficiency of 82.6%. Additionally, the VCuS/MXene electrode material is utilized as an electrochemical glucose sensor for the precise detection of H2O2 down to a minimal concentration of H2O2/mm, exhibiting exceptional precision. The use of multifunctional VCuS/MXene nanocomposite electrode material presents novel possibilities for the construction of hybrid energy harvesting systems.
|
|
| 3. |
- Alay-e-Abbas, Syed Muhammad, 1983-, et al.
(författare)
-
Structure inversion asymmetry enhanced electronic structure and electrical transport in 2D A3SnO (A = Ca, Sr, and Ba) anti-perovskite monolayers
- 2023
-
Ingår i: Nano Reseach. - : Springer Nature. - 1998-0124 .- 1998-0000. ; 16:1, s. 1779-1791
-
Tidskriftsartikel (refereegranskat)abstract
- Anti-perovskites A3SnO (A = Ca, Sr, and Ba) are an important class of materials due to the emergence of Dirac cones and tiny mass gaps in their band structures originating from an intricate interplay of crystal symmetry, spin-orbit coupling, and band overlap. This provides an exciting playground for modulating their electronic properties in the two-dimensional (2D) limit. Herein, we employ first-principles density functional theory (DFT) calculations by combining dispersion-corrected SCAN + rVV10 and mBJ functionals for a comprehensive side-by-side comparison of the structural, thermodynamic, dynamical, mechanical, electronic, and thermoelectric properties of bulk and monolayer (one unit cell thick) A3SnO anti-perovskites. Our results show that 2D monolayers derived from bulk A3SnO anti-perovskites are structurally and energetically stable. Moreover, Rashba-type splitting in the electronic structure of Ca3SnO and Sr3SnO monolayers is observed owing to strong spin-orbit coupling and inversion asymmetry. On the other hand, monolayer Ba3SnO exhibits Dirac cone at the high-symmetry Γ point due to the domination of band overlap. Based on the predicted electronic transport properties, it is shown that inversion asymmetry plays an essential character such that the monolayers Ca3SnO and Sr3SnO outperform thermoelectric performance of their bulk counterparts.
|
|
| 4. |
|
|
| 5. |
- Ghumman, Iss, et al.
(författare)
-
Computational Fluid Mechanics Model for Numerical Investigation of Frictional Tribo-pair during Mixed Lubrication
- 2022
-
Ingår i: Proceedings of 2022 19th International Bhurban Conference on Applied Sciences and Technology, IBCAST 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665460514 ; , s. 815-820
-
Konferensbidrag (refereegranskat)abstract
- All the machines are constructed through mechanical links and pairs. One of the crucial pairs is the sliding pair; due to their nature and general use, they are often subjected to a higher degree of dynamics and external forces leading to high frictional force. To reduce wear from friction formerly thick film of commercial oil is used. However, viscosity-based higher thickness yields higher energy losses, and nano-lubricants are popular in reducing friction while keeping film thickness and improving wear resistance. This paper develops a numerical model for sliding pairs that predicts the load carried by components under different lubrication regimes. The aim is to simulate hydrodynamic and mixed lubrication regimes for different loading conditions. A detailed multiphysics model of tribo-pair was modeled, including lubricant rheology, surface topology, oil film squeeze, and film temperature through the moving mesh. The fluid domain has been meshed with Arbitrary Lagrangian and Eulerian techniques. Energy loss due to viscous friction and boundary friction were determined by solving Naiver- Stokes equations in the moving mesh deformable geometry domain. The numerical model was compared with the available literature, and the results are presented. This numerical simulation remained valid and provides the fundamental understanding of oil film thickness and load-carrying capacity of sliding tribo-pair in the presence of nano-lubricants. The developed model is a useful methodology for studying lubricant oil enriched with nanoparticles.
|
|
| 6. |
- Goyal, Nitin, et al.
(författare)
-
Medical Management vs Mechanical Thrombectomy for Mild Strokes: An International Multicenter Study and Systematic Review and Meta-analysis
- 2020
-
Ingår i: JAMA Neurology. - : American Medical Association (AMA). - 2168-6149. ; 77:1, s. 16-24
-
Tidskriftsartikel (refereegranskat)abstract
- © 2019 American Medical Association. All rights reserved. Importance: The benefit of mechanical thrombectomy (MT) in patients with stroke presenting with mild deficits (National Institutes of Health Stroke Scale [NIHSS] score <6) owing to emergency large-vessel occlusion (ELVO) remains uncertain. Objective: To assess the outcomes of patients with mild-deficits ELVO (mELVO) treated with MT vs best medical management (bMM). Data Sources: We retrospectively pooled patients with mELVO during a 5-year period from 16 centers. A meta-analysis of studies reporting efficacy and safety outcomes with MT or bMM among patients with mELVO was also conducted. Data were analyzed between 2013 and 2017. Study Selection: We identified studies that enrolled patients with stroke (within 24 hours of symptom onset) with mELVO treated with MT or bMM. Main Outcomes and Measures: Efficacy outcomes included 3-month favorable functional outcome and 3-month functional independence that were defined as modified Rankin Scale scores of 0 to 1 and 0 to 2, respectively. Safety outcomes included 3-month mortality and symptomatic and asymptomatic intracranial hemorrhage (ICH). Results: We evaluated a total of 251 patients with mELVO who were treated with MT (n = 138; 65 women; mean age, 65.2 years; median NIHSS score, 4; interquartile range [IQR], 3-5) or bMM (n = 113; 51 women; mean age, 64.8; median NIHSS score, 3; interquartile range [IQR], 2-4). The rate of asymptomatic ICH was lower in bMM (4.6% vs 17.5%; P =.002), while the rate of 3-month FI (after imputation of missing follow-up evaluations) was lower in MT (77.4% vs 88.5%; P =.02). The 2 groups did not differ in any other efficacy or safety outcomes. In multivariable analyses, MT was associated with higher odds of asymptomatic ICH (odds ratio [OR], 11.07; 95% CI, 1.31-93.53; P =.03). In the meta-analysis of 4 studies (843 patients), MT was associated with higher odds of symptomatic ICH in unadjusted analyses (OR, 5.52; 95% CI, 1.91-15.49; P =.002; I2 = 0%). This association did not retain its significance in adjusted analyses including 2 studies (OR, 2.06; 95% CI, 0.49-8.63; P =.32; I2 = 0%). The meta-analysis did not document any other independent associations between treatment groups and safety or efficacy outcomes. Conclusions and Relevance: Our multicenter study coupled with the meta-analysis suggests similar outcomes of MT and bMM in patients with stroke with mELVO, but no conclusions about treatment effect can be made. The clinical equipoise can further be resolved by a randomized clinical trial.
|
|
| 7. |
- Sahil, Mehran, et al.
(författare)
-
Seismic performance evaluation of exterior reinforced concrete beam-column connections retrofitted with economical perforated steel haunches
- 2024
-
Ingår i: Results in Engineering (RINENG). - : Elsevier. - 2590-1230. ; 22
-
Tidskriftsartikel (refereegranskat)abstract
- The exterior beam-column joint (BCJ) within reinforced concrete (RC) frame structures is acknowledged as a vulnerable component prone to seismic failure. This article proposes a practical and economical strengthening method for exterior BCJs using a perforated steel haunch system. This method is designed to mitigate damage in BCJs and improve the seismic performance of the structure. Employing finite element modeling (FEM) techniques, the study evaluates the impact of perforated steel haunches on the BCJs’ behavior and performance. The investigation involves creating nine distinct models, each representing a BCJ with a steel haunch system. These models include a control model without any perforations and eight variations with different levels of perforation (ranging from 10% to 50%) within the steel haunch system. Furthermore, the study analyzes the influence of perforation shapes on the connections’ performance, considering square, circular, hexagonal, and triangular shapes. The results reveal that utilizing a steel haunch without perforations significantly increases the load-carrying capacity of a BCJ by about 89%. Additionally, circular or square-shaped perforations, up to 30–35% within the steel haunch, effectively prevent the joints’ failure and promote the ductile behavior. These findings hold the potential to advance the design methodology for RC joints subjected to seismic loads, thereby enhancing the structural resilience in earthquake-prone regions.
|
|
| 8. |
- Saif-Ul-Allah, Muhammad Waqas, et al.
(författare)
-
Computationally Inexpensive 1D-CNN for the Prediction of Noisy Data of NOx Emissions From 500 MW Coal-Fired Power Plant
- 2022
-
Ingår i: Frontiers in Energy Research. - : FRONTIERS MEDIA SA. - 2296-598X. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Coal-fired power plants have been used to meet the energy requirements in countries where coal reserves are abundant and are the key source of NOx emissions. Owing to the serious environmental and health concerns associated with NOx emissions, much work has been carried out to reduce NOx emissions. Sophisticated artificial intelligence (AI) techniques have been employed during the past few decades, such as least-squares support vector machine (LSSVM), artificial neural networks (ANN), long short-term memory (LSTM), and gated recurrent unit (GRU), to develop the NOx prediction model. Several studies have investigated deep neural networks (DNN) models for accurate NOx emission prediction. However, there is a need to investigate a DNN-based NOx prediction model that is accurate and computationally inexpensive. Recently, a new AI technique, convolutional neural network (CNN), has been introduced and proven superior for image class prediction accuracy. According to the best of the author's knowledge, not much work has been done on the utilization of CNN on NOx emissions from coal-fired power plants. Therefore, this study investigated the prediction performance and computational time of one-dimensional CNN (1D-CNN) on NOx emissions data from a 500 MW coal-fired power plant. The variations of hyperparameters of LSTM, GRU, and 1D-CNN were investigated, and the performance metrics such as RMSE and computational time were recorded to obtain optimal hyperparameters. The obtained optimal values of hyperparameters of LSTM, GRU, and 1D-CNN were then employed for models' development, and consequently, the models were tested on test data. The 1D-CNN NOx emission model improved the training efficiency in terms of RMSE by 70.6% and 60.1% compared to LSTM and GRU, respectively. Furthermore, the testing efficiency for 1D-CNN improved by 10.2% and 15.7% compared to LSTM and GRU, respectively. Moreover, 1D-CNN (26 s) reduced the training time by 83.8% and 50% compared to LSTM (160 s) and GRU (52 s), respectively. Results reveal that 1D-CNN is more accurate, more stable, and computationally inexpensive compared to LSTM and GRU on NOx emission data from the 500 MW power plant.
|
|
| 9. |
- Waqas, Muhammad, 1983, et al.
(författare)
-
Simultaneous X-ray Video-Fluoroscopy and Pulsed Ultrasound Velocimetry Analyses of the Pharyngeal Phase of Swallowing of Boluses with Different Rheological Properties
- 2020
-
Ingår i: Dysphagia. - : Springer Science and Business Media LLC. - 0179-051X .- 1432-0460. ; 35:6, s. 898-906
-
Forskningsöversikt (refereegranskat)abstract
- The Ultrasound Velocity Profiling (UVP) technique allows real-time, non-invasive flow mapping of a fluid along a 1D-measuring line. This study explores the possibility of using the UVP technique and X-ray video-fluoroscopy (XVF) to elucidate the deglutition process with the focus on bolus rheology. By positioning the UVP probe so that the pulsed ultrasonic beam passes behind the air-filled trachea, the bolus flow in the pharynx can be measured. Healthy subjects in a clinical study swallowed fluids with different rheological properties: Newtonian (constant shear viscosity and non-elastic); Boger (constant shear viscosity and elastic); and shear thinning (shear rate-dependent shear viscosity and elastic). The results from both the UVP and XVF reveal higher velocities for the shear thinning fluid, followed by the Boger and the Newtonian fluids, demonstrating that the UVP method has equivalent sensitivities for detecting the velocities of fluids with different rheological properties. The velocity of the contraction wave that clears the pharynx was measured in the UVP and found to be independent of bolus rheology. The results show that UVP not only assesses accurately the fluid velocity in a bolus flow, but it can also monitor the structural changes that take place in response to a bolus flow, with the added advantage of being a completely non-invasive technique that does not require the introduction of contrast media.
|
|
| 10. |
- Ahmad, Naveed, et al.
(författare)
-
Relationship between corporate social responsibility at the micro-level and environmental performance : The mediating role of employee pro-environmental behavior and the moderating role of gender
- 2021
-
Ingår i: Sustainable Production and Consumption. - : Elsevier BV. - 2352-5509. ; 27, s. 1138-1148
-
Tidskriftsartikel (refereegranskat)abstract
- Since Pakistan is vulnerable to changing climatic conditions, the country needs emergency measures at every level to mitigate their effect. Many studies have addressed Corporate Social Responsibility (CSR) at the macro or institutional level, but its effect at the micro-level is largely ignored in the contemporary literature. The present study aims at filling this gap by highlighting the role of micro-level CSR on Environmental Performance (ENP) and how it is influenced by employees’ pro-environmental (PEB) behavior and gender. This study has been carried out in the context of deteriorating environmental conditions, scarce CSR activities and a male dominant society. Data were collected through a self-administered questionnaire targeting the manufacturing and the service sectors of Pakistan and analyzed through the structural equation modeling technique, using AMOS and SPSS software. The results of this study confirm that micro-level CSR initiatives directly (β = 0.39⁎⁎) and indirectly (β = 0.031⁎⁎) influence the environmental performance of an organization by means of employees’ PEB. A conditional indirect gender effect on this interaction was also observed, with women (β =0.17⁎⁎) exerting a stronger effect than men (β = 0.031⁎⁎). These findings may be helpful for policymakers involved in environmental management: It is possible to reduce the environmental footprint of Pakistan's organizations by encouraging employee's PEB and particularly by actively involving women which are systematically set apart from decision making in Pakistan.
|
|
