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73 result(s) for "Mehmood, Y"
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Numerical study of Maxwell nanofluid flow with MWCNT and SWCNT considering quartic autocatalytic reactions and Thompson-Troian slip mechanism
The impact of the Thompson and Troian slip restrictions on continuous nanofluid flow, including CNTs near the stagnation point with constricting/enlarging surfaces, examined using a mathematical model. Engine oil is utilized as the base liquid, and both single-wall (SWCNTs) and multi-wall (MWCNTs) carbon nanotubes are taken into consideration. A Darcy-Forchheimer permeable medium and quartic autocatalysis, a chemical reaction for MHD stagnation point flow, are used to study the heat and flow characteristics of non-Newtonian flow. The original mathematical model is also expanded to include the impact of buoyancy forces. The numerical solution of non-dimensional velocity, temperature, and concentration profiles is obtained using the MATLAB-created bvp4c function, which employs the three-stage Lobatto IIIa formula. In the limited case, the validity of the recommended mathematical model is assessed by comparison with published work. A strong consensus is reached in this regard. Many dimensionless flow parameters, including the velocity slip parameter, the inertial coefficient, solid volume fraction, magnetic parameter, and the velocity parameter, have graphical representations that illustrate their behavior. Surface drag force estimates are presented to analyze the consequences on the extended surface. It has been demonstrated that increasing the slip velocity parameter boosts fluid flow speed while reducing surface drag. The efficiency of local thermal transmission decreases as the endothermic/exothermic coefficient rises. The altering viscosity factor for nanofluids causes an increase in axial velocity while a decrease in temperature distribution. Engine oil enriched with MWCNT and SWCNT can improve the thermal conductivity and viscosity of lubricants, leading to reduce wear and tear and better engine performance as well. Furthermore the incorporation of quartic autocatalytic reactions can enhance chemical processes that rely on catalysis, improving reaction rates. Also it has diverse applications in the system of cooling devices, manufacturing and material processing and heat transfer systems. It is revealed through this study that the system is shown to moderately cool off as measured by the solid volume ratio and heat generation. The velocity ratio parameter and the thermal expansion parameter had opposing outcomes on the system’s internal heat transfer mechanism.Article HighlightsAs we increase the volume fraction of nanoparticles, the velocity of the fluid diminishes while temperature profile exhibits enlargement.Temperature of the fluid flow portrays the fall off pattern for the enhanced values of thermal relaxation time.An enhancement in the exothermic and endothermic factor shows lowering the concentration profile.
MHD stagnation point flow and heat transfer in viscoelastic fluid with Cattaneo–Christov heat flux model
This article presents an analysis of stagnation point of coupled flow and heat transfer of an upper-convected Maxwell fluid over a stretching sheet along with magnetic effects and slip condition at the boundary. The recently proposed Cattaneo–Christov model is employed in the energy equation to investigate the effects of thermal relaxation time. Similarity transformations are adopted to convert the governing partial differential equations into ordinary differential equations. Numerical solution of the system of ODEs is achieved by shooting method together with Runge–Kutta method of order four. The effects of stretching ratio parameter (0 ≤  e  ≤ 0.5), elasticity number (0 ≤  β  ≤ 1.5), heat flux relaxation time (0 ≤  γ  ≤ 1.5), magnetic parameter (0 ≤  M  ≤ 1.5), slip coefficient (1 ≤  b  ≤ 4) and Prandtl number (0 ≤ Pr ≤ 1.5) on velocity and temperature are investigated graphically and numerically. It is observed that temperature boosts up with an increase in thermal relaxation time.
Electrosprayed Polymeric Nanospheres for Enhanced Solubility, Dissolution Rate, Oral Bioavailability and Antihyperlipidemic Activity of Bezafibrate
Bezafibrate is a BCS class II drug as it presents very low solubility in water; therefore, its bioavailability after oral administration is very poor. The aim of this work was to enhance solubility and dissolution rate of bezafibrate in water in order to enhance its oral bioavailability. Several formulations were prepared using PVP K30 and Cremophor ELP employing the solvent-evaporation method and the electrospraying technique. Solubility, release rate, bioavailability in male Sprague Dawley rats, and lipid profile attributes in Wistar rats were assessed in comparison with bezafibrate plain powder. Solid-state characterization was carried out using X-ray diffraction (XRD) analysis, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). All the formulations exerted positive effect towards the desired goal. In particular, the optimized formulation furnished about 14-fold enhanced solubility and 85.48 ± 10.16% drug was released in 10 min as compared with bezafibrate alone (4.06 ± 2.59%). The drug existed in the amorphous state in the prepared sample as confirmed by XRD and DSC, whilst no drug-excipient interactions were observed through FTIR analysis. Moreover, SEM revealed smooth-surfaced spherical particles of the optimized formulation. A 5.5-fold higher oral bioavailability was achieved with the optimized formulation in comparison with bezafibrate plain powder. Also, TG, LDL and TC were decreased, and HDL was increased considerably in HFD-treated rats. The optimized formulation consisting of bezafibrate, PVP K30 and cremophor ELP (1/12/1.5, w/w/w) might be a capable drug delivery system for orally administering poorly water-soluble bezafibrate with improved bioavailability and antihyperlipidemic effects.
ASSEMBLY PERFORMANCE OF A GASKETED BOLTED FLANGED PIPE JOINT USING DIFFERENT BOLT TIGHTENING STRATEGIES
This article presents the results of the assembly process of a gasketed bolted flanged pipe joint for two different bolt tightening strategies, ie ASME and Industrial using torque control of preload method. The final clamping force is achieved in four and five passes in ASME and Industrial strategy, respectively. Axial bolt stress variation, at the end of each pass, individual bolt bending behavior, gasket stress and flange stress variations for both strategies are discussed.
Electrospun Gelatin Nanocontainers for Enhanced Biopharmaceutical Performance of Piroxicam: In Vivo and In Vitro Investigations
Piroxicam exhibits low oral bioavailability, due to its meager solubility in water. The intent of this study was to ameliorate the bioavailability of the drug by employing a solubility-enhancing encapsulation technique. Seven samples were formulated with piroxicam and gelatin using both solvent evaporation and electrospraying together. Evaluation of solubility and release rate in water and assessment of bioavailability in rats were carried out in comparison with piroxicam plain drug powder (PPDP). Other in vitro explorations were accomplished using powder X-ray diffraction analysis, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and Fourier-transform infrared spectroscopy. All piroxicam-loaded gelatinnanocontainers (PLGNs) enhanced solubility and release of the payload in water. In particular, a PLGN formulation consisting of piroxicam and gelatin at a 1:8 (w:w) ratio presented about 600-fold the drug solubility of that shown by PPDP. Moreover, 85.12%±10.96% of the payload was released from this formulation in 10 minutes which was significantly higher than that dissolved from PPDP in 10 minutes (11.81%±5.34%). Drug content, drug loading, and encapsulation efficiency of this formulation were 93.41%±0.56%, 10.45%±0.06%, and 66.74%±6.87%, respectively. The drug loaded in PLGNs existed in the amorphous state, as confirmed by X-ray diffraction and differential scanning-calorimetry analyses, and was more stable when analyzed by thermogravimetric analysis. Moreover, Fourier-transform infrared spectroscopy analysis suggested nonexistence of any piroxicam-gelatin interaction in the formulation. In the scanning electron-microscopy image, PLGNs appeared as round, smooth particles, with particle size of <1,000 nm. Amelioration in bioavailability of piroxicam with the aforementioned PLGN formulation was fourfold that of PPDP. The PLGN formulation fabricated with piroxicam and gelatin at 1:8 (w:w) might be a promising system for enhanced biopharmaceutical performance of the drug.
Evidence of recent increased pathogenicity within the Australian Ascochyta rabiei population
Ascochyta Blight (AB), caused by Ascochyta rabiei (syn Phoma rabiei), is the major endemic foliar fungal disease affecting the Australian chickpea industry, resulting with potential crop loss and management costs. This study was conducted to better understand the risk posed by the Australian A. rabiei population to current resistance sources and to provide informed decision support for chemical control strategies. Recent changes in the pathogenicity of the population were proposed based on disease severity and histopathological observations on a host set. Controlled environment disease screening of 201 isolates on the host set revealed distinct pathogenicity groups, with 41% of all isolates assessed as highly aggressive and a significant increase in the proportion of isolates able to cause severe damage on resistant and moderately resistant cultivars since 2013. In particular, the frequency of highly aggressive isolates on the widely adopted PBA HatTrick cultivar rose from 18% in 2013 to 68% in 2017. In addition, isolates collected since 2016 caused severe disease on Genesis 090, another widely adopted moderately resistant cultivar and on ICC3996, a commonly used resistance source. Of immediate concern was the 10% of highly aggressive isolates able to severely damage the recently released resistant cultivar PBA Seamer (2016). Histopathology studies revealed that the most aggressive isolates were able to germinate, develop appressoria and invade directly through the epidermis faster than lower aggressive isolates on all hosts assessed, including ICC3996. The fungal invasion triggered a common reactive oxygen species (ROS) and hypersensitive response (HR) on all assessed resistant genotypes with initial biochemical and subsequent structural defence responses initiated within 24 hours of inoculation by the most highly aggressive isolates. These responses were much faster on the less resistant and fastest on the susceptible check host, indicating that speed of recognition was correlated with resistance rating. This will inform fungicide application timing so that infected crops are sprayed with prophylactic chemistries prior to invasion and with systemic chemistries after the pathogen has invaded. Competing Interest Statement The authors have declared no competing interest.
Increased Silver Activity for Direct Propylene Epoxidation via Subnanometer Size Effects
Production of the industrial chemical propylene oxide is energy-intensive and environmentally unfriendly. Catalysts based on bulk silver surfaces with direct propylene epoxidation by molecular oxygen have not resolved these problems because of substantial formation of carbon dioxide. We found that unpromoted, size-selected Ag₃ clusters and approximately 3.5-nanometer Ag nanoparticles on alumina supports can catalyze this reaction with only a negligible amount of carbon dioxide formation and with high activity at low temperatures. Density functional calculations show that, relative to extended silver surfaces, oxidized silver trimers are more active and selective for epoxidation because of the open-shell nature of their electronic structure. The results suggest that new architectures based on ultrasmall silver particles may provide highly efficient catalysts for propylene epoxidation.
Interventions to Reduce Hospital Length of Stay in High-risk Populations
Many strategies to reduce hospital length of stay (LOS) have been implemented, but few studies have evaluated hospital-led interventions focused on high-risk populations. The Agency for Healthcare Research and Quality (AHRQ) Learning Health System panel commissioned this study to further evaluate system-level interventions for LOS reduction. To identify and synthesize evidence regarding potential systems-level strategies to reduce LOS for patients at high risk for prolonged LOS. Multiple databases, including MEDLINE and Embase, were searched for English-language systematic reviews from January 1, 2010, through September 30, 2020, with updated searches through January 19, 2021. The scope of the protocol was determined with input from AHRQ Key Informants. Systematic reviews were included if they reported on hospital-led interventions intended to decrease LOS for high-risk populations, defined as those with high-risk medical conditions or socioeconomically vulnerable populations (eg, patients with high levels of socioeconomic risk, who are medically uninsured or underinsured, with limited English proficiency, or who are hospitalized at a safety-net, tertiary, or quaternary care institution). Exclusion criteria included interventions that were conducted outside of the hospital setting, including community health programs. Data extraction was conducted independently, with extraction of strength of evidence (SOE) ratings provided by systematic reviews; if unavailable, SOE was assessed using the AHRQ Evidence-Based Practice Center methods guide. Our searches yielded 4432 potential studies. We included 19 systematic reviews reported in 20 articles. The reviews described 8 strategies for reducing LOS in high-risk populations: discharge planning, geriatric assessment, medication management, clinical pathways, interdisciplinary or multidisciplinary care, case management, hospitalist services, and telehealth. Interventions were most frequently designed for older patients, often those who were frail (9 studies), or patients with heart failure. There were notable evidence gaps, as there were no systematic reviews studying interventions for patients with socioeconomic risk. For patients with medically complex conditions, discharge planning, medication management, and interdisciplinary care teams were associated with inconsistent outcomes (LOS, readmissions, mortality) across populations. For patients with heart failure, clinical pathways and case management were associated with reduced length of stay (clinical pathways: mean difference reduction, 1.89 [95% CI, 1.33 to 2.44] days; case management: mean difference reduction, 1.28 [95% CI, 0.52 to 2.04] days). This systematic review found inconsistent results across all high-risk populations on the effectiveness associated with interventions, such as discharge planning, that are often widely used by health systems. This systematic review highlights important evidence gaps, such as the lack of existing systematic reviews focused on patients with socioeconomic risk factors, and the need for further research.
Source differences in the components and cytotoxicity of PM2.5 from automobile exhaust, coal combustion, and biomass burning contributing to urban aerosol toxicity
Although air quality guidelines generally use the atmospheric concentration of fine particulate matter (PM2.5) as a metric for air pollution evaluation and management, the fact cannot be ignored that different particle toxicities are unequal and significantly related to their sources and chemical compositions. Therefore, judging the most harmful source and identifying the toxic component would be helpful for optimizing air quality standards and prioritizing targeted PM2.5 control strategies to protect public health more effectively. Since the combustions of fuels, including oil, coal, and biomass, are the main anthropogenic sources of environmental PM2.5, their discrepant contributions to health risks of mixed ambient aerosol pollution dominated by the respective emission intensity and unequal toxicity of chemical components need to be identified. In order to quantify the differences between these combustion primary emissions, 10 types of PM2.5 from each typical source group, i.e., vehicle exhaust, coal combustion, and plant biomass (domestic biofuel) burning, were collected for comparative study with toxicological mechanisms. In total, 30 types of individual combustion samples were intercompared with representative urban ambient air PM2.5 samples, whose chemical characteristics and biological effects were investigated by component analysis (carbon, metals, soluble ions) and in vitro toxicity assays (cell viability, oxidative stress, inflammatory response) of human lung adenocarcinoma epithelial cells (A549). Carbonaceous fractions were plenteous in automobile exhaust and biomass burning, while heavy metals were more plentiful in PM2.5 from coal combustion and automobile exhaust. The overall ranking of mass-normalized cytotoxicity for source-specific PM2.5 was automobile exhaust > coal combustion > domestic plant biomass burning > ambient urban air, possibly with differential toxicity triggers, and showed that the carbonaceous fractions (organic carbon, OC; elemental carbon, EC) and redox-active transition metals (V, Ni, Cr) assisted by water-soluble ions (Ca2+, Mg2+, F-, Cl-) might play important roles in inducing cellular reactive organic species (ROS) production, causing oxidative stress and inflammation, resulting in cell injury and apoptosis, and thus damaging human health. Coupled with the source apportionment results of typical urban ambient air PM2.5 in eastern China, reducing toxic PM2.5 from these anthropogenic combustions will be greatly beneficial to public health. In addition to the air pollution control measures that have been implemented, like strengthening the vehicle emission standards, switching energy from coal to gas and electricity, and controlling the open incineration of agricultural straws, further methods could be considered, especially by preferentially reducing the diesel exhaust, lessening the coal combustion by replacement with low-ash clean coals, and depressing the rural crop straw biomass burning emissions.