Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 57
Filtrar
1.
PLoS One ; 19(4): e0299454, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38625894

RESUMO

This paper develops an outsourcing collaboration model from a firm's perspective operating in a developing economy. The model considers that producers of the final goods residing in a developed country, and operators of manufacturing plants in a developing country collaborate with each other. The final goods producer supplies headquarter services for the production of intermediate goods in the developing country. The operators of manufacturing plants also supply their services in the domestic economy. This arrangement leads to foreign outsourcing collaborations (FOC) between firms of developed country and developing country. The operators of manufacturing plant maximize revenue subject to the cost constraint. The first order conditions suggests that an increase in wages of skilled labor, price of domestic inputs, and cost of production deter FOC. On the other hand, an increase in demand for and price of foreign headquarter services increases the FOC. Empirical analysis based on data collected from 217 clothing (textile and apparel) firms in the city of Faisalabad (Pakistan) reveals that an increase in wage to labor-productivity ratio reduces FOC. An improvement in skilled of the labor and foreign headquarter services give rise to FOC, whereas an increase in economies-of-scope enhances FOC. Additionally, an inverted U-shaped relationship is found between the cost of production and FOC, which shows that at the initial stage, the firm's cost of production increases with an increase in the level of FOC, but soon after the tipping point, the firm's cost starts decreasing with a further increase in FOC.


Assuntos
Serviços Terceirizados , Indústria Têxtil , Humanos , Paquistão , Comércio , Salários e Benefícios
2.
Heliyon ; 10(4): e26126, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38384558

RESUMO

Poly-herbal therapies for chronic diseases like diabetes mellitus (DM) have been practiced in south Asia for centuries. One of such therapies comprises of Hordeum vulgare, Elettaria cardamomum and Cicer arietinum that have shown encouraging therapeutic potential in the treatment of diabetes and obesity. Therefore, poly-herbal granules (PHGs) of this formula were developed and investigated for their anti-diabetic and anti-obesity potential in obese-diabetic rats. The developed PHGs were chemical characterized and the virtual molecular docking was performed by Discovery studio visualizer (DSV) software. For in-vivo experiment, obesity in rats was induced with high-fat high-sugar diet. After that, diabetes was induced by alloxan monohydrate 150 mg/kg i.p. injection. The diseased rats were treated with PHGs at 250, 500 and 750 mg/kg/day for four weeks. GC-MS analysis of PHGs demonstrated the presence of 1,3-Benzenedicarboxylic acid bis(2-ethylhexyl) ester and 1,2-Benzenedicarboxylic acid di-isooctyl ester and phenol, 2,4-bis(1,1-dimethylethyl). Molecular docking of these compounds demonstrated higher binding energies with receptor than metformin against α-amylase and α-glucosidase. PHGs exhibited a decline in body weight, HbA1c, hyperlipidemia, hyperglycemia, and insulin resistance in diseased rats. The histopathological examination revealed that PHGs improved the alloxan-induced damage to the pancreas. Furthermore, PHGs increased the SOD, CAT and GSH while and the decreased the level of MDA in the liver, kidney and pancreas of diseased rats. Additionally, the PHGs had significantly downregulated the TNF-α and NF-κB while upregulated the expression of NrF-2. The current study demonstrated that the PHGs exhibited anti-diabetic and anti-obesity potential through amelioration of oxidative stress, NF-κB, TNF-α, and NrF-2 due to the presence of different phytochemicals.

3.
Chem Commun (Camb) ; 60(17): 2385-2388, 2024 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-38321968

RESUMO

We present a red light-activated zincII bis(dipyrrin) symmetry breaking charge transfer (SBCT) architecture, showing a large molar absorption coefficient (ε = 15.4 × 104 M-1 cm-1), high reactive singlet oxygen generation efficiency (ΦΔ ≈ 0.8) and long-lived triplet state (τT = 150 µs) compared to the donor-acceptor analogue dipyrrin-BF2 complex, highlighting the superiority of the SBCT approach. For the first time, we demonstrated the potential of a SBCT scaffold in red-light-induced methyl methacrylate (MMA) polymerization, using a dual photocatalyst excitation approach.

4.
Pak J Pharm Sci ; 36(6): 1823-1829, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38124423

RESUMO

Anxiolytic effect of ethanol, hexane extracts and pure compounds ß- sito sterol glucoside and bergenin isolated from Adenanthera pavonina AP (Fabaceae) and Peltophorum pterocarpum PP (Fabaceae) leaves were monitored in this study. Mice were treated with dose of 125mg/kg body weight of ethanol and hexane leaves extracts of both tested plants while, 5mg/kg body weight of ß-sito sterol glucoside and 25mg/kg body weight of bergenin. The effect was monitored by hole board test, forced swimming test, open field apparatus and stationary rod test. Results from neuropharmacological effects revealed that ethanol extract of AP leaves and hexane extract of PP leaves had significant anxiolytic (forced swimming test) exploratory (head dip and open field test) and neuro activator activity (stationary rod test) at tested dose. The greatest anti-depressant and anxiolytic effect was found in ethanol extract of AP leaves when compared to all treated drugs. A part from memory enhancing effects, diazepam treated mice also exhibited anxiolytic and antidepressant effects and found comparable with ethanol extract of AP. These findings may clarify the impact of ethanol, hexane extracts and pure substances ß-sitosterol glucoside and bergenin at tested concentrations, as well as their potential to treat the Parkinson's and related disorders as an alternative therapy.


Assuntos
Ansiolíticos , Fabaceae , Camundongos , Animais , Ansiolíticos/farmacologia , Ansiolíticos/uso terapêutico , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Hexanos , Depressão/tratamento farmacológico , Etanol/farmacologia , Ansiedade/tratamento farmacológico , Peso Corporal , Glucosídeos/farmacologia , Esteróis/farmacologia , Comportamento Animal
5.
Heliyon ; 9(11): e21107, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37928015

RESUMO

The magnetohydrodynamic (MHD) rotating flow that occurs across a stretching surface has numerous practical applications in a variety of domains. These fields include astronomy, engineering, the material sciences, and space exploration. The combined examination of magnetohydrodynamics rotating flow across a stretching surface, taking into consideration fluctuating viscosity and nanoparticle aggregation, has significant ramifications across several different domains. It is essential for both the growth of technology and the attainment of deeper insights into the complicated fluid dynamics to maintain research in this field. Given the aforementioned motivation, the principal aim of this study is to examine the effects of variable viscosity on the bidirectional rotating magnetohydrodynamic flow over a stretching surface. Aggregation effects on nanoparticles are used in the analysis. Titania (TiO2) is taken nanoparticle and ethylene glycol as base fluid. The nonlinear ordinary differential equations and the boundary conditions that correspond to them can be transformed into a dimensionless form by using a technique called similarity transformation. To get a numerical solution to the transformed equation, the Runge-Kutta 4th order (RK-4) method is utilized, and this is done in conjunction with the shooting method. The impact of various leading variables on dimensionless velocity, the coefficients of temperature, skin friction and local Nusselt number are graphically represented. Velocity profiles in both direction increases with increasing values of φ. The Nusselt number increases with increasing values of the radiation and temperature ratio parameters. When a 1 % volume fraction of nanoparticles is introduced, the Nusselt number exhibits a 0.174 % increase for the aggregation model compared to the regular fluid in the absence of radiation effects. When the aggregation model is used with a 1 % volume fraction of nanoparticles, the skin friction increases by 0.1153 % in the x direction and by 0.1165 % in the y direction compared to the regular fluid. Tables show the variation in Nusselt numbers, as well as a comparison of the effects of nanoparticle's aggregation model without and with radiation. Moreover, the numerical results obtained were compared with previously published data, demonstrating a satisfactory agreement. We firmly believe that this finding will have extensive implications for engineering and various industries.

6.
Heliyon ; 9(9): e19292, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37662785

RESUMO

Diabetes mellitus (DM) is the most prevalent endocrine disorder. Numerous individual herbs possess anti-diabetic activity. The seeds of Hordeum vulgare, Elettaria cardamomum and Cicer arietinum are traditionally used to manage DM. The ambition of this work was to formulate the poly-herbal granules (PHGs) comprising of these three functional foods and evaluate their in-vitro antioxidant and antidiabetic potential. The dried seed extracts of Hordeum vulgare, Elettaria cardamomum and Cicer arietinum were used in a ratio of 2.5:1:1 to formulate PHGs by wet granulation method. The ratio of extracts was selected on the basis of traditional phytotherapies popularly used by local Hakeems of Pakistan to achieve glycemic control in diabetic patients resistant to traditional allopathic regime of medicine. The flow properties of developed PHGs were evaluated. The UV-Visible spectroscopic, Fourier Transform Infrared (FTIR) and HPLC-DAD of all seed extracts and PHGs were performed. The in-vitro antioxidant DPPH, FRAP, total antioxidant capacity (TAC) and Nitric Oxide (NO) scavenging assays were carried out on PHGs. The in-vitro antidiabetic activity of PHGs was investigated by alpha-amylase and alpha-glucosidase enzyme inhibition activity. The developed PHGs exhibited excellent flow properties. The UV-Vis spectra of all seed extracts and PHGs demonstrated peak at 278 nm showing the presence of flavonoids and phenols. The FTIR spectra confirmed the existence of flavonoids, and phenols along with amines in seed extracts as well as PHGs. The HPLC-DAD test revealed the existence of gallic acid, ascorbic acid, Quercetin-3-(caffeoyldiglucoside)-7-glucoside, Rosmarinic acid, delphinidin-3,5-diglucosides, Kaempferol-3-feruloylsophoroside-7-glucoside and Phloroglucinol in PHGs. The PHGs exhibited IC50 of 51.23, 58.57, 55.41 and 53.13 µg/mL in DPPH assay, FRAP assay, TAC, Nitric oxide scavenging assays respectively. The PHGs also demonstrated IC50 of 49.97 and 36.16 µg/mL in alpha-amylase and in alpha-glucosidase inhibition assays respectively in dose dependent manner. The developed PHGs exhibited an excellent flow property. These exhibit significant in-vitro antioxidant and antidiabetic profile by virtue of flavonoid and phenolic acid derivatives.

7.
Angew Chem Int Ed Engl ; 62(44): e202312600, 2023 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-37654187

RESUMO

The design of efficient heavy atom-free triplet photosensitizers (PSs) based on through bond charge transfer (TBCT) features is a formidable challenge due to the criteria of orthogonal donor-acceptor geometry. Herein, we propose using parallel (face-to-face) conformation carbazole-bodipy donor-acceptor dyads (BCZ-1 and BCZ-2) featuring through space intramolecular charge transfer (TSCT) process as efficient triplet PS. Efficient intersystem crossing (ΦΔ =61 %) and long-lived triplet excited state (τT =186 µs) were observed in the TSCT dyad BCZ-1 compared to BCZ-3 (ΦΔ =0.4 %), the dyad involving TBCT, demonstrating the superiority of the TSCT approach over conventional donor-acceptor system. Moreover, the transient absorption study revealed that TSCT dyads have a faster charge separation and slower intersystem crossing process induced by charge recombination compared to TBCT dyad. A long-lived charge-separated state (CSS) was observed in the BCZ-1 (τCSS =24 ns). For the first time, the TSCT dyad was explored for the triplet-triplet annihilation upconversion, and a high upconversion quantum yield of 11 % was observed. Our results demonstrate a new avenue for designing efficient PSs and open up exciting opportunities for future research in this field.

8.
Heliyon ; 9(6): e17538, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37408888

RESUMO

It is still not quite apparent how suspended nanoparticles improve heat transmission. Multiple investigations have demonstrated that the aggregation of nanoparticles is a critical step in improving the thermal conductivity of nanofluids. However, the thermal conductivity of the nanofluid would be greatly affected by the fractal dimension of the nanoparticle aggregation. The purpose of this research is to learn how nanoparticle aggregation, joule heating, and a heat source affect the behavior of an ethylene glycol-based nanofluid as it flows over a permeable, heated, stretched vertical Riga plate and through a porous medium. Numerical solutions to the present mathematical model were obtained using Mathematica's Runge-Kutta (RK-IV) with shooting technique. In the stagnation point flow next to a permeable, heated, extending Riga plate, heat transfer processes and interrupted flow phenomena are defined and illustrated by diagrams in the proposed mixed convection, joule heating, and suction variables along a boundary surface. Data visualizations showed how different variables affected temperature and velocity distributions, skin friction coefficient, and the local Nusselt number. The rates of heat transmission and skin friction increased when the values of the suction parameters were raised. The temperature profile and the Nusselt number both rose because of the heat source setting. The increase in skin friction caused by changing the nanoparticle volume fraction from φ=0.0 to φ=0.01 for the without aggregation model was about 7.2% for the case of opposing flow area (λ=-1.0) and 7.5% for the case of aiding flow region (λ=1.0). With the aggregation model, the heat transfer rate decreases by approximately 3.6% for cases with opposing flow regions (λ=-1.0) and 3.7% for cases with assisting flow regions (λ=1.0), depending on the nanoparticle volume fraction and ranging from φ=0.0 to φ=0.01, respectively. Recent findings were validated by comparing them to previously published findings for the same setting. There was substantial agreement between the two sets finding.

9.
Heliyon ; 9(7): e17673, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37449139

RESUMO

The transfer of heat is a phenomenon that is significant in a variety of contexts due to the different ways in which it may be utilized in industrial settings. To increase the rate at which heat is transferred, carbon nanotubes (CNTs), which can either be single-wall or multi-walled, are suspended in base fluids, and the resulting mixture is referred to as a "nanofluid. This study looks at how heat transfers through nanofluids that are suspended in carbon nanotubes with different lengths and radii over a stretching surface. It also looks at how changing viscosity and joule heating affect motion. Water is taken as base fluid. This study looks at both carbon nanotubes with one wall and those with more than one. The flow is governed by a series of partial differential equations, which, to control the flow, are transformed into a series of nonlinear ordinary differential equations. Similarity transformation is used to convert the obtained nonlinear ordinary differential equations and accompanying boundary conditions into a form that is dimensionless. To numerically solve the transformed equation, RK-4 with shooting method is used. Graphs and in-depth discussions are used to look at how velocity and temperature profiles are affected by the leading variables. The expression for skin friction and local Nusselt number are written down and graphs show how these two numbers change for different parameter values. The temperature profile goes down when the viscosity parameter goes down, but the velocity profile goes up. When the magnetic parameter goes up, the velocity profile f'(η), goes down, but the velocity profile g(η) and temperature θ(η) both go up at the same time. The rate of heat transfer increases with the addition of φ and S. When the suction parameter (S = 2.1) with 1% of φ is used, it is reported that rate of heat transfer increases by 1.135% for Single walled and 1.275% for Multi Walled carbon nanotubes. To determine whether or not the proposed numerical model is legitimate, a comparison is made between the current results and those that have previously been published.

10.
Sci Prog ; 106(2): 368504231176151, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37226474

RESUMO

The study of boundary layer flows over an irregularly shaped needle with small horizontal and vertical dimensions is popular among academics because it seems to have a lot of uses in fields as different as bioinformatics, medicine, engineering, and aerodynamics. With nanoparticle aggregation, magnetohydrodynamics, and viscous dissipation all playing a role in the flow and heat transmission of an axisymmetric TiO2-C2H6O2 nanofluid via a moving thin needle, this article provides guidance on how to employ a boundary layer for this purpose. In this case, we utilized the similarity transformation to change the dimensional partial differential equation into the dimensionless ordinary differential equation. We utilize MATHEMATICA to include shooting using RK-IV methods after identifying the numerical issue. Several characteristics were measured, leading to the discovery of a broad variety of values for things like skin friction coefficients, Nusselt numbers, velocity profiles, and temperature distributions. Velocity profile decreases with increasing values of ϕ,M,e and increases against ε. Temperature profiles enhances with increasing values of ϕ,M,e,ε, and Ec. The reduction in skin friction between a needle and a fluid can be observed when the values of M and ϕ are boosted. Furthermore, it was also noticed an increase in heat transfer on needle surface dramatically when ϕ,e, and M were raised, whereas Ec displayed the opposite effect. The findings of the current study are compared with prior findings for a particular instance in order to confirm the findings. Excellent agreement between the two sets of results is found.

11.
Heliyon ; 9(4): e15012, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37089338

RESUMO

Significance of study: Nanofluids with aggregation effects mediated by nanoparticles, like geothermal panels and crossflow heat exchangers, ignite new industrial interests. Polymer and conversion processes have transport phenomena in the stagnation zone that must be continuously improved to raise the process quality standard. Aim of study: Hence, the current computational study examines a T i O 2 - C 2 H 6 O 2 nanofluid's unsteady stagnation-point flow performance via a shrinking horizontal cylinder. In addition, the effects of a magnetic field, joule-heating viscous dissipation, nanoparticles aggregation and mass suction on the boundary layer flow are reflected. Method: ology: The RK-IV with shooting method is applied to resolve the simplified mathematical model numerically in computing software MATHEMATICA. In certain circumstances, comparing the current and prior findings indicates good agreement with a relative error of around 0%. Findings: The implementation of a heat transfer operation may be improved by increasing suction settings. Unsteadiness, nanoparticle volume fraction, magnetic, curvature, and Eckert number (implies the operating Joule heating and viscous dissipation) all influence heat transfer rate. The velocity and temperature profiles both increase as the unsteadiness, magnetic field, and nanoparticle volume fraction parameters increase, whereas the curvature and suction parameters show the opposite behavior. When the values of the suction parameters were changed from 2.0 to 2.5 with φ  = 0.01, the heat transfer rates rose by 4.751%. A comparison shows that the model with aggregation has a better velocity profile, while the model without aggregation has a better temperature profile.

12.
Heliyon ; 9(3): e14472, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36967874

RESUMO

To aid in the prevention of reaction explosions, chemical engineers and scientists must analyze the Arrhenius kinetics and activation energies of chemical reactions involving binary chemical mixtures. Nanofluids with an Arrhenius kinetic are crucial for a broad variety of uses in the industrial sector, involving the manufacture of chemicals, thermoelectric sciences, biomedical devices, polymer extrusion, and the enhancement of thermal systems via technology. The goal of this study is to determine how the presence of thermal radiation influences heat and mass transfer during free convective unsteady stagnation point flow across extending/shrinking vertical Riga plate in the presence of a binary chemical reaction where the activation energy of the reaction is known in advance. For the purpose of obtaining numerical solutions to the mathematical model of the present issue the Runge-Kutta (RK-IV) with shooting technique in Mathematica was used. Heat and mass transfer processes, as well as interrupted flow phenomena, are characterized and explained by diagrams in the suggested suction variables along boundary surface in the stagnation point flow approaching a permeable stretching/shrinking Riga Plate. Graphs illustrated the effects of many other factors on temperature, velocity, concentration, Sherwood and Nusselt number as well as skin friction in detail. Velocity profile increased with Z , λ and S and decreased with ε . Increasing values of ε , λ and S decline the temperature profile. The concentration profile boosts up with Z , α and slow down with ε , S c , ß , δ and n 1 parameters. Skin friction profile increased with Z and S and decreased with ε . Nusselt number profile increased with S , Z , ε and radiation. Sherwood number profile shows upsurges with ε , Z , α , S c , ß , S and n 1 whereas slow down with δ . So that the verdicts could be confirmed, a study was done to compare the most recent research with the results that had already been published for a certain case. The outcomes demonstrated strong concordance between the two sets of results.

13.
Front Pharmacol ; 14: 1066018, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36937845

RESUMO

Introduction: A SeDeM expert tool-driven I-optimal mixture design has been used to develop a directly compressible multiparticulate based extended release minitablets for gastro-retentive drug delivery systems using loxoprofen sodium as a model drug. Methods: Powder blends were subjected to stress drug-excipient compatibility studies using FTIR, thermogravimetric analysis, and DSC. SeDeM diagram expert tool was utilized to assess the suitability of the drug and excipients for direct compression. The formulations were designed using an I-optimal mixture design with proportions of methocel K100M, ethocel 10P and NaHCO3 as variables. Powder was compressed into minitablets and encapsulated. After physicochemical evaluation lag-time, floating time, and drug release were studied. Heckel analysis for yield pressure and accelerated stability studies were performed as per ICH guidelines. The in silico PBPK Advanced Compartmental and Transit model of GastroPlus™ was used for predicting in vivo pharmacokinetic parameters. Results: Drug release follows first-order kinetics with fickian diffusion as the main mechanism for most of the formulations; however, a few formulations followed anomalous transport as the mechanism of drug release. The in-silico-based pharmacokinetic revealed relative bioavailability of 97.0%. Discussion: SeDeM expert system effectively used in QbD based development of encapsulated multiparticulates for once daily administration of loxoprofen sodium having predictable in-vivo bioavailability.

14.
J Natl Med Assoc ; 115(3): 273-282, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36914542

RESUMO

The decision tree used a generating set of rules based on various correlated variables for developing an algorithm from the target variable. Using the training dataset this paper used boosting tree algorithm for gender classification from twenty-five anthropometric measurements and extract twelve significant variables chest diameter, waist girth, biacromial, wrist diameter, ankle diameter, forearm girth, thigh girth, chest depth, bicep girth, shoulder girth, elbow girth and the hip girth with an accuracy rate of 98.42%, by seven decision rule sets serving the purpose of dimension reduction.


Assuntos
Braço , Aprendizado de Máquina , Humanos , Árvores de Decisões
15.
Heliyon ; 9(3): e14248, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36925526

RESUMO

Significance of study: Typical liquids aren't great for engineering because of their low heat conductivity. To enhance heat transfer capabilities in industries as diverse as computers, pharmaceuticals, and molten metals, researchers and scientists have developed nanofluids, which are composed of nanoparticles distributed in a base fluid. Aim of study: Mathematical modeling of micropolar C u - H 2 O nanofluid driven by a deformable sheet in the stagnation area with nanoparticle aggregation, thermal radiation, and the mass suction action has been investigated in this paper. In this case, copper ( C u ) nanoparticles make up the nanofluid. Method: ology: We have used suitable transformations to arrive at a system of nonlinear ODEs, which we then solve numerically in MATHEMATICA using Runge-Kutta methods of the fourth order coupled with shooting approaches. Findings: Tables and graphs are used to examine the effects of immersed flow and display profiles of physical parameters of interest. This includes velocities, temperatures, skin friction, and Nusselt numbers. The average heat transfer rate increased to 17 . 725 % as the volume percentage of copper nanoparticles in micropolar nanofluid increased from 0.0 to 0.01 . Additionally, the results showed that the local Nusselt number of the micropolar nanofluid increased along with an increase in the unsteady and radiation parameters. However, its value is reduced in an undeniable fashion if a material parameter is present. The impact of radiation on the aggregation of nanoparticles is compared and contrasted with the effects of a non-radiative scenario, and the resulting fluctuations in Nusselt numbers are provided in tables. When the results of this study were compared to data that had already been published about some cases, a lot of agreement was found.

16.
Heliyon ; 9(2): e13224, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36798773

RESUMO

The stretched surface's convective heat transfer capability can be improved by using nanoparticles. There is a significant role of the Prandtl number in determining the thermal and momentum stretching layer surfaces. It is proposed in this study that an effective Prandtl number model be used to explore the two-dimensional oblique stagnation point flow of γ A l 2 O 3 - H 2 O and γ A l 2 O 3 - C 2 H 6 O 2 nanofluids moving over a convective stretching surface. The fluid in question is subjected to a thorough investigation. It is necessary to apply non-linear ordinary differential equations in order to connect the controlling partial differential equations with the boundary conditions. To solve these equations, an efficient and reliable numerical technique is used. Shooting Method with Runge Kutta-IV in Mathematica software. Visual representations of normal and tangential velocity and temperature as well as streamlines as a function of many physical parameters are shown. The results show that as the volume fraction of nanoparticles increases, the fluid flow f ( y ) , h ( y ) and velocity f ' ( y ) , h ' ( y ) all increase, whereas the flow f ( y ) and velocity f ' ( y ) both increase against the stretching ratio parameter, while the flow h ( y ) and velocity h ' ( y ) both decrease. When the volume percentage of nanoparticles and the Biot number are both increased, the temperature rises. However, when the stretching ratio parameter is increased, the temperature falls. Physical attributes like the local skin friction coefficient and the heat flow may be characterized in many ways. A nanofluid comprised of γ A l 2 O 3 - C 2 H 6 O 2 outperformed a γ A l 2 O 3 - H 2 O nanofluid in terms of heat transfer rate. The source of zero skin friction may be observed to move to the left or right depending on the balance of obliqueness and straining motion at point x s . The computed numerical results of the current research correspond well with those accessible in the literature for the limiting scenario.

17.
Sci Prog ; 106(1): 368504221149798, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36651004

RESUMO

In numerous industrial procedures, the main concern of design engineers is ensuring adequate heat and mass transfer, such as in the heating and cooling practices of solar water heaters, geothermal systems, extrusion of metal, insulation of buildings, electronics, turbines, aerodynamics, electronics, paper manufacturing, and glass fiber production. The unsteady double-diffusive mixed convection flow of boundary layer nanofluids above a vertical region near stagnation point flow is developed and examined here. The Brownian motion and thermophoresis effects are incorporated by using Buongiorno's model. In the thermal energy equations, diffusion of regular and cross types is also used. By the use of the local similarity method along with suitable similarity transformations, nonlinear unsteady partial differential equations are converted to nonlinear ordinary differential equations and are numerically solved by the Keller-Box method. The investigation expresses that these profiles of solute concentration and nanoparticle concentration, temperature, and velocity in their boundary layers, respectively, depending on several parameters. A graphic analysis of all these parameters' possessions on nature's boundary layers is depicted. The highest rate of heat transfer is obtained with negligible thermophoresis effect. Furthermore, it is perceived that an increase in Nc and Nt results in a reduction in the reduced Sherwood number of nanoparticles, whereas addition results in an increase in the Nb number. There is a reverse effect on the temperature field and layer thickness for heat generation. In the wake of the above-mentioned potential applications, the current study of fluid flow has been found to be very interesting and innovative in the analysis of the influence of Brownian motion and thermophoresis effects near stagnation point flow, which will further make revolutions in industrial fields. Moreover, Buongiorno's model predicts the characteristics of double-diffusive fluids in enhancing heat transfers. This investigation has been established as a result of the numerous industrial applications mentioned above.

18.
Sci Prog ; 106(1): 368504231152741, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36703499

RESUMO

As a result of the many real-world applications that may be derived from understanding stagnation point flow in designing, such as the coolant of nuclear reactors, there has been a great deal of interest in the topic. Consequently, the purpose of this research was to offer a numerical analysis of an unstable three-dimensional (3D) nodal stagnation point flow of polymer-based Al2O3-CuO-TiO2/polymer ternary nanofluid past a stretching surface with mass suction and heat source effects. In order to simplify the underlying partial differential equations, an appropriate similarity transformation is applied to them. This simplifies the ordinary differential equations. The shooting with the Runge-Kutta approach is used by the MATHEMATICA software to do the numerical calculation. Suction, stretching, unsteadiness, heat source, and nanoparticle volume fractions are other elements that play a role in regulating the flow and heat transfer as well as drag force profiles and how they affect the problem. The amount of heat transferred, and the friction coefficient increased in both directions when the suction parameter values were raised. In a ternary-hybrid nanofluid, the overall heat transfer rate decreases as the value of the heat source increases. Variations in the nanoparticles' volume fraction parameter cause an intensification in skin friction in both directions. Expanding the unstable and nanoparticles volume fraction parameters also reduces the Nusselt number. Furthermore, the heat transfer presentation of ternary-hybrid nanofluid has superior to the hybrid nanofluid and the normal nanofluid for the suction parameter. When the results of the current research were compared to those of a study that had already been done and published, they were found to be in good agreement.

19.
Chemistry ; 29(1): e202202677, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36250277

RESUMO

Tuning the redox potential of commonly available photocatalyst to improve the catalytic performance or expand its scope for challenging synthetic conversions is an ongoing demand in synthetic chemistry. Herein, the excited state properties and redox potential of commercially available [Ru(bpy)3 ]2+ photocatalyst were tuned by modifying the structure of the bipyridine ligands with electron-donating/withdrawing units. The visible-light-mediated photoredox phosphorylation of tertiary aliphatic amines was demonstrated under mild conditions. A series of cross-dehydrogenative coupling reactions were performed employing the RuII complexes as photocatalyst giving the corresponding α-aminophosphinoxides and α-aminophosphonates via carbon-phosphorus (C-P) bond formation.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...