Search

The importance of the fuel injection configuration on the propulsion efficiency of high-speed vehicles is apparent. In this article, the use of an annular extruded 4-lobe nozzle for the injection of fuel jet in a supersonic combustor of a scramjet engine in the existence of a shock generator is examined. The main aim of this study is to obtain the efficient jet arrangement for efficient fuel mixing inside the engine of hypersonic vehicles. A numerical approach is used to model the supersonic air stream and cross-jet flow with the SST turbulence model. The role of nozzle altitude and internal air jet on the fuel mixing of the hydrogen within the high-speed domain are disclosed. The importance of the horseshoe vortex and counter-rotating vortex on the fuel distribution is also presented. Our results show that the usage of a coaxial jet instead of an annular jet would increase fuel mixing by more than 40% in the combustion chamber. [ABSTRACT FROM AUTHOR]

Nanofluid rheology and heat transfer were lately the subjects of several research and investigations. In this paper, an experimental investigation was used to investigate the influence of temperature and volume fraction of nanoparticles on dynamic viscosity (µ nf) of WO 3 -Multi-Walled Carbon Nanotubes (MWCNT)-SiO 2 / water-EG ternary hybrid nanofluids. The impacts of these factors were also evaluated on mono nanofluids. The nanofluids were made using a two-step process at solid volume fractions of nanoparticles (SVF) of 0.2 to 0.6% and temperatures ranging from T = 20 to 60 °C. The zeta-potential test was used to measure the stability of nanofluids. According to the obtained results, the nanofluids have high qualities. A Brookfield viscometer was used to measure the µ nf. All volume fractions of nanoparticles show that µ nf decreases with temperature rise. At all temperatures, the µ nf increases as the SVF increase, regardless of temperature. The results showed that in ternary nanofluids the highest amount of viscosity is related to the SVF = 0.6% and the T = 20 °C, which shows a value of 79.7% increase compared to the base fluid at the same temperature. Also, among mono nanofluids, the highest amounts of viscosity were observed for MWCNT at all temperatures and volume fractions. Finally, a mathematical model for calculating the µ nf is established. The results of the proposed models were well correlated with laboratory data. The results of the established model show an acceptable correlation with experimental data. [ABSTRACT FROM AUTHOR]

In this study, our primary objective was to synthesize and characterize a copper nanoparticle-modified oxidized graphite carbon nitride (ox-g-C3N4). This modified ox-g-C3N4 material was utilized as a reusable catalyst for the environmentally friendly production of benzofuran 4(a-j) derivatives through C–H activation using an electrochemical oxidation system. The desired derivatives were obtained by reacting 2-bromophenol 1(a-c) with ethynylbenzene 2(a-g) yielding high yields ranging from 89 to 94%. The modified Cu/ox-g-C3N4 nanocomposite was thoroughly examined. using different analytical techniques, including thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), IR Fourier-transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET) analysis, cyclic voltammetry (CV), and X-ray diffraction (XRD) spectroscopy, and ultraviolet (UV) spectroscopy. The comprehensive identification was conducted in a comparative manner, allowing for a thorough understanding of the nanocomposite's properties. By employing this nanocatalyst, we implement a greener synthesis approach that reduces the need for dangerous and toxic substances, while reducing waste generation by promoting reuse. The synthesized products in this research were subjected to characterization utilizing techniques such as melting point analysis, CHN analysis and 1HNMR spectroscopy. These analytical methods were utilized to confirm the identification and assess the purity of the benzofuran compounds synthesized 4(a-j). [ABSTRACT FROM AUTHOR]

The present paper examines turbulent flow and heat transfer characteristics of a three-dimensional laterally perforated finned heat sink (LPFHS) using response surface methodology (RSM) and computational fluid dynamics (CFD) approaches. The effects of the Reynolds number and perforations geometry, such as porosity (size) and cross-sectional shape (square, circular, hexagonal, and triangular), were investigated on the average friction factor and average Nusselt number. RSM is an applicable approach to improve process conditions by analyzing the impact of different factors and their interdependence on the measured outcomes during a specific technological operation. Three accurate models for the percentage of heat transfer enhancement (PHTE), the percentage of friction factor reduction (PFCR), and the percentage of weight reduction (PWR) as the most important design objectives for heat sinks were proposed using the RSM technique. RSM models served as the foundation for two- and three-objective optimizations. Results demonstrate that fins with square perforations exhibited the highest PHTE value. Additionally, fins with square, circular, and hexagonal perforations experienced increased PFCR with rising porosity at different Reynolds numbers. Fins with square perforations were particularly effective in PWR because the perforations matched well with the lateral surfaces of the fin. The optimal conditions for the LPFHS were achieved using square perforations with Reynolds number and porosity values of 2101 and 0.494, respectively. In the optimal case, PHTE, PFCR, and PWR increased by 7.965%, 24.198%, and 49.367%, respectively, compared to the base case (solid fin). In addition, the optimization strategy implemented in the present study allows weighting of the objectives, which leads to flexible designs. By assigning importance coefficients to each objective, the designer can obtain a set of optimal designs that meet different requirements or trade-offs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The concept of nanofluid includes suspensions containing nanoparticles, metallic and non-metallic materials. • The present research investigates the thermal properties, Brownian motion, and thermophoresis of water/ graphene nanofluid. • This investigation reported changes in heat flux, thermal conductivity, average Brownian displacement, and thermophoresis. • The results depicted that by raising the initial pressure, average Brownian displacement and thermophoresis values decreased. • By raising the initial pressure, the amount of heat flux and thermal conductivity after 10 ns decrease. The concept of nanofluid includes suspensions containing nanoparticles, metallic and non-metallic materials. Nanofluids have many potentials in different environments and conditions that make them exist in industries and food industries. Considering their high thermal conductivity, the nanoparticles increased the fluid's thermal conductivity, one of the basic heat transfer parameters, when distributed in the base fluid. The present research investigated the thermal properties, Brownian motion, and thermophoresis of water/ graphene nanofluid affected by different ratios of initial pressure (1, 2, 3 and 5 bar) by molecular dynamics simulation. This study reported the changes in heat flux, thermal conductivity, average Brownian displacement, and thermophoresis. The results depict that by increasing the initial pressure from 1 to 5 bar, average Brownian displacement and thermophoresis values decrease from 06.3 and 23.88 to 2.91 and 23.53 Å, respectively. Also, by raising the initial pressure (1 to 5 bar), the heat flux and thermal conductivity after 10 ns decrease from 39.54 and 0.36 to 35.12 W/m2 and 0.28 W/m.K, and the maximum temperature reduces from 1415 K to 1033 K. These results can be useful in different industries, especially for improving the thermal properties of different nanofluids. [ABSTRACT FROM AUTHOR]

• We investigated the thermal behaviors of the ammonia-copper nanofluid using MD. • Effect of increasing the volume fraction of nanoparticles on thermal behavior of nanofluids was investigated. • The atomic behavior of the simulated structure was investigated. • By increasing the volume fraction of nanoparticles, the heat flux and aggregation duration increase. Nanofluids, fluids containing nanometer-sized particles, have significant properties which make them useful in devices and systems. They boost thermal conductivity and heat transfer better than base fluid. This research studied the atomic behavior, and thermal behavior of simulated ammonia-copper nanofluid using molecular dynamics (MD) simulation method. The effect of increasing Cu nanoparticles' volume fraction (φ) (1–10 %) on the atomic behavior and thermal behavior of nanofluids was studied. The atomic behavior of simulated structure was studied with velocity and temperature profiles. The maximum values of velocity and temperature were 0.00086 Å/ps and 240 K, respectively. To study the thermal behavior of simulated structure, heat flux and the aggregation time (AT) of nanoparticles (NPs) were studied. Numerically, the heat flux (HF) and the aggregation time of Ammonia-Cu nanofluid converged to 1411 W/m2 and 3.96 ns, respectively. The study showed that the maximum velocity and temperature decreased by increasing φ. Moreover, by increasing the φ to 5 %, the heat flux and aggregation time increase to 1553 W/m2 and 4.05 ns. By more increase of NPs up to 10 %, the heat flux and AT of samples decrease. By increasing NPs by 10 % in the base fluid, the aggregation process of NPs occurred in a shorter time. It reduces the thermal efficiency of simulated samples. [ABSTRACT FROM AUTHOR]

In current computational research, the effect of Polycaprolactone (PCL) coating on the mechanical properties (MP) of biomimetic calcium phosphate (BCP)/Baghdadite (BG)-AK nanocomposite (NC) is investigated by using molecular dynamics simulation (MDS). Our study models BCP/BG-AK-PCL samples by Universal Force Field (UFF) and DREIDING potential functions. The outcomes of MDS on the MP of atomic samples are presented by computing physical factors like temperature (Temp), potential energy (PE), Young's modulus (YM), and ultimate strength (US). Physically, MD outputs indicate the physical stability of the BCP/BG-AK-PCL sample after 5 ns. Also, by inserting the PCL coat into the pristine matrix, the YM of this structure reaches 0.39 MPa, and the US increases to 20.28 MPa. These numerical results show the important effect of PCL coats on the MP of pristine BCP/BG-AK NC, which can be used for clinical applications. [ABSTRACT FROM AUTHOR]

Today, with the advancement of science in nanotechnology, it is possible to remove dust nanostructures from the air breathed by humans or other fluids. In the present study, the separation of SiO 2 molecules from H 2 O vapor is studied using molecular dynamics (MD) simulation. This research studied the effect of initial temperature, nanopore geometry, and initial pressure on the separation of SiO 2 molecules. The obtained results show that by increasing the temperature to 500 K, the maximum velocity (Max-Vel) of the samples reached 2.47 Å/fs. Regarding the increasing velocity of particles, more particles pass via the nanopores. Moreover, the shape of the nanopore could affect the number of passing particles. The results show that in the samples with a cylindrical nanopore, 20 and 40% of SiO 2 molecules, and with the sphere cavity, about 32 and 38% of SiO 2 particles passed in the simulated structure. So, it can be concluded that the performance of carbon nanosheets with a cylindrical pore and 450 K was more optimal. Also, the results show that an increase in initial pressure leads to a decrease in the passage of SiO 2 particles. The results reveal that about 14 and 54% of Silica particles passed via the carbon membrane with increasing pressure. Therefore, for use in industry, in terms of separating dust particles, in addition to applying an EF, temperature, nanopore geometry, and initial pressure should be controlled. [Display omitted] • Separation of SiO 2 nanoparticles from H 2 O vapor is investigated. • This examination was performed with Molecular dynamics (MD) simulation. • Effect of initial temperature and nanopore geometry on the separation of nanoparticles was investigated. • As the initial temperature increase, the particles' movement increases. • Performance of carbon nanosheets with a cylindrical pore and 450 K is more optimal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Influence of carbon doping concentration on the mechanical properties of PRSA is investigated. • PRSA, under the influence of carbon doping, has dual performance. • Mechanical behavior of the PRSA matrix can be manipulated with carbon doping for actual applications. Aerogels are different types of porous and solid materials that exhibit a strange set of extraordinary material properties. Aerogels have great potential for use in the fields of heat, sound, electronics, and especially thermal insulation. This paper investigates the influence of carbon doping concentration on the mechanical properties of paraffin-reinforced silica aerogel (PRSA). To do this investigation, Young's module (YM), stress–strain curve, and ultimate strength (US) values at various carbon-doped particles of 1 to 10 % were reported by molecular dynamics (MD) simulation. The results show that the PRSA, under the influence of carbon doping, has dual performance. To be more precise, by adding the amount of carbon doped from 1 to 3 %, the US and YM of the PRSA rose from 329.96 and 1137.20 MPa to 353.73 and 1268.44 MPa. In other words, the mechanical strength of the PRSA increases in a limited ratio. However, by increasing carbon doping from 3 to 10 %, the US and YM of the PRSA reduced to 306.233 and 1041.88 MPa, respectively. So, it is expected that the mechanical behavior of the PRSA matrix to be manipulated with carbon doping for actual applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Molecular dynamics method was implemented. • The present research investigates the influence of palladium percentage and oxygen ratio on air-methane catalytic combustion. • Combustion performance in the presence of excess oxygen and oxygen deficiency is reported. • Increasing palladium percentage improves the combustion performance. • Oxygen and palladium ratios can benefit the combustion process. Combustion is an exothermic chemical process between an explosive substance and an oxidizing agent that is accompanied by heat generation and chemical change of raw materials. Catalysts are used in a combustion process for various reasons, including the speed at which the material reaches equilibrium. Catalysts are chemicals that increase the rate of reaction in chemical processes. The present research investigates the influence of palladium percentage and oxygen ratio on air-methane catalytic combustion in a helical microchannel. For this purpose, the atomic behavior and combustion performance of the simulated sample in the presence of excess oxygen and oxygen deficiency is reported by the molecular dynamics (MD) method. The potential functions used in this paper were Lennard-Jones, the embedded atom model (EAM), and Coulomb. It is concluded that increasing palladium percentage in limited ratios improves the atomic and combustion performance of the simulated structure, and this enhancement is greater in the presence of excess oxygen. In the presence of excess oxygen, the numerical value of maximum density, velocity and temperature converged from 0.138 atom/Å3, 0.33 Å/ps and 523 K to 0.144 atom/Å3, 0.36 Å/ps and 539 K, respectively with increasing palladium percentage from 1 % to 4 %. And by increasing the palladium ratio to 10 %, these numerical values decrease to 0.137 atom/Å3, 0.31 Å/ps and 530 K. Moreover, in the presence of oxygen deficiency, heat flux, thermal conductivity, and combustion efficiency of atomic samples reached 2049 W/m2, 1.23 W/m.K and 90 % after rising palladium to 4 %, and it decreased to 2035 W/m2, 1.19 W/m.K and 86 % by adding 10 % palladium. Therefore, the results indicate that the oxygen and the catalyst (palladium) ratios can benefit the combustion process. These results can optimize the atomic performance and combustion performance of structures essential for use in various industries. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of Solid Volume Fraction (SVF) and temperature on the dynamic viscosity of a hybrid antifreeze composed of MWCNTs and aluminum oxide in a mixture of water (80%) and ethylene-glycol (20%). An Artificial Neural Network (ANN) is used to predict the viscosity of the nanofluid, which was generated at different SVFs ranging from 0.25% to 1% and temperatures ranging from 25 °C to 50 °C. This study aims to establish a correlation between viscosity and input parameters in the antifreeze. Results demonstrate that Shear Rate (SR) and SVF have opposite effects on the viscosity of the nanofluid. Increasing SVF leads to a strong increase in viscosity deviation and higher mean values of viscosity while increasing SR results in a sharp decline in both the mean value and variation of the viscosity. The temperature has a smaller impact on viscosity variance than SR and SVF. The proposed ANN model with a two-layer network and 13 neurons having nonlinear activation functions in the hidden layer shows an accurate prediction of viscosity versus inputs. The proposed methodology offers an improvement of up to 10 times in predicting viscosity accuracy as compared to GMDH and decision tree techniques. The findings of this study can have important implications for the design of heat exchangers using nanofluids especially in portable devices. [ABSTRACT FROM AUTHOR]

• C N bond formation. • C S bond formation. • Safe oxidant. • Low cost reagent. • Reusable catalyst. In this study, our focus was on synthesizing and characterizing a fullerene modified with copper nanoparticles. This modified fullerene catalyzes for the eco-friendly synthesis of benzothiazole 5(a-m) derivatives. These derivatives are obtained through the reaction of 2-iodoaniline 1(a-f) , toluene 2(a-e), and Na 2 S resulting in good yields (89–94 %). The nanocomposite catalyst underwent thorough characterization using various analytical techniques, including Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), Brunauer–Emmett–Teller (BET), Thermogravimetric analysis (TGA), Ultraviolet (UV), X-ray photoelectron spectroscopy (XPS), Cyclic voltammetry (CVs) and X Ray Diffraction Analysis (XRD) spectroscopy. By utilizing this catalyst, we achieve a more environmentally friendly approach to synthesis, reducing the requirement for hazardous and toxic reagents, and minimizing waste generation through reusability. The products obtained in this study were characterized using melting point determination, 1HNMR spectroscopy, and CHN analysis. These analytical techniques were employed to establish the identity and purity of the synthesized compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper aims to estimate the permeability of concrete by replacing the laboratory tests with robust machine learning (ML)-based models. For this purpose, the potential of twelve well-known ML techniques was investigated in estimating the water penetration depth (WPD) of nano natural pozzolana (NNP)-reinforced concrete based on 840 data points. The preparation of concrete specimens was based on the different combinations of NNP content, water-to-cement (W/C) ratio, median particle size (MPS) of NNP, and curing time (CT). Comparing the results estimated by the ML models with the laboratory results revealed that the hist-gradient boosting regressor (HGBR) and K-nearest neighbors (KNN) algorithms were the most and least robust models to estimate the WPD of NNP-reinforced concrete, respectively. Both laboratory and ML results showed that the WPD of NNP-reinforced concrete decreased with the increase of the NNP content from 1 to 4%, the decrease of the W/C ratio and the MPS, and the increase of the CT. To further aid in the estimation of concrete's WPD for engineering challenges, a graphical user interface for the ML-based models was developed. Proposing such a model may be effectively employed in the management of concrete quality. [ABSTRACT FROM AUTHOR]

The purpose of this study is numerical investigation, the laminar flow hydrodynamic and mixed convection of water-copper nanofluid in a microtube by applying the two-phase mixture method. This 3D simulation is run at Re = 10, Ri = 0.1 - 10 ) and volume fraction of nanoparticles φ = 0–6% through Finite Volume Method. The nanofluid flow is assumed Newtonian, assessed in a horizontal microtube of 90 ∘ curvature angle. The objective is to assess the impact of the buoyancy and centrifugal forces on the flow in a bent geometry. In this research, the interpretation and investigation of Nusselt Number (Nu), coefficient of friction and temperature distribution in three-dimensional macrotube with changes in volume fraction and Richardson number will be discussed. The results reveal that the nanofluids' hydrodynamic properties and behavior next to their heat transfer in bent geometries vary from those of other geometries and flat surfaces while being more trajectory dependent. The average Nusselt number and the average friction factor in the inner, outer, top, and bottom regions of the microtube strongly depend on the Ri number and φ. The increase in φ promotes the micron heat transfer mechanisms in the microtube, thus, an enhancement in the heat transfer rate. The variations in velocity components and the buoyancy and centrifugal forces are among the most influential factors on hydrodynamic and heat transfer parameters like the friction factor and Nu number. The value of the local Nu number has an ascending trend when the φ increases in the initial stage of the flow from the inlet section to the middle of the path. This is while the local Nu number decreases as the φ increases after the 45 ∘ curvature upward. The increase in the friction factor level from the entrance up to 45 ∘ angle is due to the more substantial effects of buoyancy and centrifugal forces. [ABSTRACT FROM AUTHOR]

Paying close attention to the environmental risks associated with traditional forms of energy, particularly the serious issue of global warming caused by the release and concentration of greenhouse gases, has become a paramount concern. This growing awareness has prompted governments worldwide to prioritize the benefits of alternative energy sources and develop comprehensive plans accordingly. Moreover, it is crucial to thoroughly consider and explore existing potentials in our quest for sustainable energy solutions. One such potential lies in the energy loss experienced due to gas pressure reduction in urban gas reduction stations. Furthermore, as we increase the amount of natural gas preheating, we observe a corresponding rise in the temperature within the expansion turbine, ultimately resulting in a significant boost in power generation. In this paper, we delve into the exciting possibility of harnessing electricity generation by utilizing a turbo expander within a municipal gas pressure reduction station. To maximize the work generation capacity, we propose preheating the gas input to the turbo expander using geothermal energy. Our study reveals that the turbo expander exhibits optimal performance, boasting an impressive isentropic efficiency of 92.3%, when the inlet temperature is maintained at 84 °C and the amount of preheating reaches 192.3 kJ/kg. [ABSTRACT FROM AUTHOR]

This study investigated the effect of graphene oxide nanosheet (GON) size, and initial temperature (IT) on the mechanical properties (MP), and thermal properties (TP) of epoxy/GO structure using the molecular dynamics simulation (MDS). The stress-strain curve, Young's modulus (YM), the atomic order parameter (AOP), and the thermal expansion coefficient (length changes) of simulated structures were studied. The results show that increasing GO length improved the simulated structure's MP. As the GO length increased to 20 Å, YM increased from 2.96 to 4.04 GPa. Furthermore, by changing the length of simulated GONs, the amount of van der Waals force applied from each plate to the atoms present in the atomic matrix changes; so, as the size of GONs increased, AOP in the structures increased. Increasing the size of simulated GONs reduced the expansion of structure. This behavior showed higher thermal resistance, and consequently, atomic stability in the samples as the nanosheets became larger. In general, increasing IT led to increasing the atomic fluctuations. Consequently, the attraction energy among the atoms decreased by increasing the atomic oscillations. Therefore, increasing the IT to 350 K led to a decrease in the YM of samples. Therefore, the MP of samples was reduced by increasing IT. Moreover, increasing IT decreased the amount of AOP in the samples. Finally, increasing IT increased the oscillation amplitude, and the distance of atoms from each other, which caused the expansion in the structure under study. • Molecular dynamics method was implemented. • Effects of graphene oxide nanosheet on the mechanical properties of epoxy/graphene oxide structure. • Increasing the nanosheets' length improves the simulated structure's mechanical properties. • As The length increases to 20 Å, Young's modulus increases from 2.96 to 4.04 GPa. • Increasing the size of the simulated nanosheets reduces the expansion of the structure. [ABSTRACT FROM AUTHOR]

• A copper-based electrode was utilized as the catalyst in sonogashira C-H activation coupling reactions. • This electrode was used for electro-oxidation synthesis of diphenylethyne derivatives. • The successful synthesis of diphenylethynes was achieved with high yields. In recent years, there have been significant advancements in Copper-catalyzed Sonogashira coupling reactions, employing both traditional and electro-oxidation methods for synthesizing diphenylethyne derivatives. This study focuses on the progress achieved through the utilization of copper foam electro-catalyzed Sonogashira coupling reactions in the synthesis of diphenylethyne derivatives 4(a-q) and provides insights into the future prospects of this field. The paper emphasizes the development of efficient copper foam catalysts, the optimization of reaction conditions, and potential applications of electro-oxidation reaction copper-catalyzed Sonogashira coupling in various fields, including materials chemistry and organic synthesis. The integration of electro-oxidation reactions into copper-catalyzed Sonogashira coupling reactions presents a promising approach for the efficient synthesis of diphenylethyne derivatives. The future trajectory of this field involves further advancements in catalyst design, reaction optimization, and the exploration of new applications for diphenylethyne derivatives across diverse scientific disciplines. This investigation specifically explores the electro-oxidation process of the Sonogashira reaction, utilizing a copper foam cathode and graphite anode in isopropyl alcohol (iPrOH) as the solvent and weak base. Sodium bromide (NaBr) serves as an economical and readily available electrolyte and reagent under green and sustainable conditions. The successful synthesis of a variety of diphenylethyne derivatives 4(a-q) was achieved, with notable yields ranging from 83% to 92%. [Display omitted] [ABSTRACT FROM AUTHOR]

The optimal design of heat sinks presents a challenge for engineers. Using longitudinal perforations is an innovative technique employed in the design of parallel finned heat sinks that can be applied to various equipment. This technique leads to the simultaneous improvement of the heat transfer rate, pressure drop, and weight of heat sinks. The size (φ) and shape of the perforations alongside the Reynolds number are considered design variables. The results obtained from machine learning showed that the combinatorial algorithm is more reliable in modeling various objectives compared to the GMDH neural networks. The Pareto fronts generated by the NSGA-II algorithm indicated that >75% of the optimal points in the perforated-finned heat sinks (PFHSs) with square perforations had a φ ≥ 0.6. The reason for this superiority is the geometric compatibility between the square perforations and rectangular fins. This compatibility enables the possibility of enlarging the perforations, resulting in improvements in essential parameters like heat dissipation, drag force, and overall heat sink volume. Various scenarios for weighting objectives in the multi-criteria decision-making (MCDM) process revealed that square-based PFHSs with Reynolds numbers around 39,900 in a wide range of perforation sizes could be applied as optimal design in real-world applications. [ABSTRACT FROM AUTHOR]

• Decreasing percentage of droplet diameter is introduced to state the fluctuation of generated droplet diameters. • Estimated formulas are presented based on experimental data. • Time evolution of EHD modes detected during experiments were physically stated. • Influence of effective parameters on droplet diameter and EHD modes are stated. The paper is an experimental investigation of the effect of process parameters like applied voltage, volume flow rate and distance between two electrodes through dimensionless numbers in the electrospray process, droplet diameter in particular. In addition, this study attempts to present new estimated formulas based on experimental data to ease primary evaluations of droplet diameter before any performing electrospray applications in order to reduce time and cost spending. For this purpose, a high-speed camera was used to have clear evidence of the influence of the parameters on the diameter of liquid droplets generated from acetic acid and their electrohydrodynamic (EHD) modes. In this study, the time evolution of EHD modes detected during experiments and the reasons for EHD mode geometric shapes were physically stated. The results show that decreasing the distance between two electrodes producing an electric field causes a reduction in the voltage to meet desired droplet diameter (needed minimum droplet diameter) and a switch of EHD modes occurs in lower voltages. This paper also demonstrates that the percentage of decreasing droplet diameter during the electrospray process has the extremum which can change based on changing effective parameters. Furthermore, a quick estimation for calculating minimum droplet diameter in dripping, spindle, and cone-jet modes based on experimental data is presented because it was observed the decreasing percentage of droplet diameters in each EHD mode is approximately constant unexpectedly whereas all effective parameters of the electrospray process in this research tested. Finally, another equation was also driven to calculate the decreasing percentage of droplet diameter based on dimensionless numbers, Weber and Electric Capillary numbers, using experimental data to acquire appropriate means for the primary forecast of the trend of droplet diameter production being useful for various of electrospray processes such as drug delivery, powder production, encapsulation, thin films, and electrospinning. [ABSTRACT FROM AUTHOR]

[Display omitted] • PCB was synthesized and identified via spectral methods. • The effects of the PCB concentration, HCl concentration, and temperature on the corrosion rate of C1018 were then confirmed. • he adsorption of PCB obeyed the Langmuir adsorption isotherm. • Adsorption process for PCB on the metal surface was exothermic, spontaneous, and comprehensive. 1,1′-(1,4-phenylene-bis (methylene)) bis(4-cyanopyridin-1-ium) bromide (PCB) was synthesized and identified via spectral methods: Fourier-transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance hydrogen (1HNMR), and proton nuclear magnetic resonance carbon (13CNMR). The inhibitory effect (% IE) was determined using weight loss (WL) method, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques for the corrosion of C1018 in strong (6 M) HCl. % IE reached 98.9 % at 200 mg/L, 313 K. The effects of the PCB concentration, HCl concentration, and temperature on the corrosion rate of C1018 were then confirmed using WL. The PDP curves indicate that PCB acts as mixed type- inhibitor. The adsorption of PCB obeyed the Langmuir adsorption isotherm. The adsorption of PCB on C1018 revealed that the adsorption process exhibiting physical and chemical adsorption. Theoretical modeling revealed the correlation between the QAS molecular chemical structure and its anticorrosive property. All the experimental and theoretical calculations were in good agreement. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel hybrid strategy is proposed to optimize water-based hybrid nanofluids. • Machine learning techniques model density, viscosity, specific heat capacity, and thermal conductivity. • Applying multi-objective optimization on the developed models leads to Pareto points. • Multi-criteria decision-making presents desirable designs according to various scenarios. The rheological and thermal behavior of nanofluids in real-world scenarios is significantly affected by their thermophysical properties (TPPs). Therefore, optimizing TPPs can remarkably improve the performance of nanofluids. In this regard, in the present study, a hybrid strategy is proposed that combines machine learning (ML), multi-objective optimization (MOO), and multi-criteria decision-making (MCDM) to select optimal parameters for water-based multi-walled carbon nanotubes (MWCNTs)-oxide hybrid nanofluids. In the first step, four critical TPPs, including density ratio (DR), viscosity ratio (VR), specific heat capacity ratio (SHCR), and thermal conductivity ratio (TCR), are modeled using two efficient ML techniques, the group method of data handling neural network (GMDH-NN) and combinatorial (COMBI) algorithm. In the next step, the superior models are subjected to a four-objective optimization by the well-known non-dominated sorting genetic algorithm II (NSGA-II), which aims to minimize DR/VR and maximize SHCR/TCR. This study considers volume fraction (VF), oxide nanoparticle (NP) type, and system temperature as optimization variables. In the final step, two prominent MCDM techniques, TOPSIS and VIKOR, were used to identify the desirable optimal points from the Pareto fronts generated by the MOO algorithm. ML results reveal the COMBI algorithm's superior reliability in accurately modeling various TPPs. The pattern of Pareto fronts for all oxide-NPs indicated that over one-third of the optimal points have a VF > 1.5 %. On the other hand, the distribution of optimal points across different temperature ranges varied significantly depending on the type of oxide-NPs. For Al 2 O 3 -based nanofluid, around 90 % of the optimal points were within 40–50 °C. Conversely, for nanofluids containing CeO 2 NPs, only approximately 24 % of the optimal points were found within the same temperature range. Considering diverse scenarios for weighting TPPs in the MCDM process implied that combining CeO 2 /ZnO oxide-NPs with MWCNTs in water-based nanofluids is highly effective across various real-world applications. [ABSTRACT FROM AUTHOR]

The usage of zigzag multi-jet configuration for efficient fuel circulation along the supersonic combustion chamber has been extensively examined in this article. To analyze the flow and fuel jet interactions, computational fluid dynamic is applied as an efficient technique to visualize the flow and fuel jet in the zigzag injection system. Injection via an annular nozzle is compared with coaxial air and fuel jet to find the effective mechanism for well-organized fuel mixing in the combustion chamber of the scramjet engine. The circulation and fuel mixing of the zigzag injection is inspected at a supersonic air stream with Mach = 4. The contour of the Mach value and stream shows that the deflection of the air stream after contact with the core of the upstream jet redirects to the core of the downstream jet and consequently, the fuel mixing is enhanced in the combustion chamber. The usage of an internal air jet expands the performance of fuel mixing of annular jets up to 100 % in the zigzag nozzle arrangement. • The role of zigzag injector for fuel mixing of hydrogen jet in combustion chamber is investigated. • Computational method is applied to model fuel jet in supersonic cross flow. • Fuel mixing and shock wave interactions in zigzag arrangements are comprehensively studied. [ABSTRACT FROM AUTHOR]

Today, nanotubes are used in biological systems due to their low toxicity and unique functionalization capability. Carbon nanotubes (CNTs) are considered one of the best carriers in drug delivery systems. In this study, the effect of silicon (Si) doping and atomic defects on the CNT's nano-pumping process has been investigated by molecular dynamics (MD) simulation, and the changes in kinetic energy, potential energy, entropy, stress, and nano-pumping time are investigated. The results show that increasing Si doping increases CNT's C 20 molecule exit time. Numerically, as the Si doping increases from 0.05% to 4%, the exit time of the C 20 molecule increases from 8.07 to 9.16 ps. Also, an increase in Si doping leads to a decrease in kinetic energy and lattice stress and an increase in the potential energy and entropy of the system. So, the nanostructure with 1% doping performs better (optimal performance) than other samples. The effect of atomic defect with 0.5%, 1% and 1.5% on CNT's surface is investigated. The results show that the kinetic energy of samples decreases by increasing atomic defect from 0.5% to 1.5%. Also, the results show that the kinetic energy of the sample with a 0.5% atomic defect is higher than its defect-free state. The numerical results show that potential energy and entropy increase with the increasing the atomic defect. This increase can lead to an increase in the time it takes for the nanoparticle to exit the nanotube and disrupt the nano-pumping process. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of constant heat flux on the adsorption of doxorubicin by bio-MOF-11 biocarrier using molecular dynamics simulation. The research explores the behavior of drug molecule and carrier under different thermal conditions to understand the underlying mechanisms of adsorption. The modeled samples were made of bio-MOF-11 structure, trisodium phosphate buffer (as a drug), and aqueous environment in the presence of NaCl. Technically, the atomic interaction among various atoms inside a computational box was described using a Universal Force Field. The findings of this study could contribute to the development of more effective drug delivery systems and advance the understanding of the adsorption process in carriers. The present outputs predicted the external heat flux was an important parameter in the atomic evolution of the drug-MOF system. The 0.3 W/m2 value of heat flux was optimum for drug diffusion into the MOF sample. Numerically, the number of diffused drug particles and diffusion coefficient converged to 335 and 73.19 nm2/ns (respectively) in the optimum value of heat flux. So, it was concluded that heat flux implementation to the drug-MOF system and changing this external parameter manipulated the drug adsorption (drug delivery) procedure in the designed system for various clinical applications. [ABSTRACT FROM AUTHOR]

This study aims to investigate the viscosity behavior of multi-walled carbon nanotube (MWCNT) - titanium dioxide (TiO 2) (40−60) - SAE50 oil nanofluid using an Artificial Neural Network (ANN) modeling approach. The main objective is to develop a highly accurate predictive model for viscosity by considering three input parameters: temperature, solid volume fraction (SVF), and shear rate (SR). Rheological measurements provide experimental data used to train and validate the ANN model. The ANN model's architecture, activation functions, and training algorithms are carefully chosen. Data are divided to three subsets including train, validation and test. ANN is trained using trainlm algorithm for 50 times to vanish the effect of random nature of ANN weight initialization. The trained ANN model is then utilized to predict the viscosity of the nanofluid under varying conditions. The results demonstrate the efficacy of the proposed ANN model in capturing the complex relationship between viscosity and the input parameters, providing accurate viscosity predictions for the MWCNT-TiO 2 -oil SAE50 nanofluid. Furthermore, the influence of temperature, SVF, and SR on viscosity is analyzed, offering valuable insights into the flow behavior of the nanofluid. According to the obtained results, the developed ANN model presents a reliable and efficient approach to estimate the viscosity of the MWCNT-TiO 2 -SAE50 oil nanofluid, eliminating the need for costly and extensive experimental measurements within the analyzed range. ANN could model the nanofluid viscosity with R2 = 0.9998 and MSE= 0.000189 that is quite acceptable. Also, the experimental data revealed that for the investigated nanofluid, temperature and shear rate have impressive effect on the viscosity (changing viscosity more than 100% for the analyzed margin), on the other hand, the nanoparticle volume fraction effect is much lower, to be more precise, increasing the nanoparticle percentage will increase the viscosity mean value around 30%. • This study investigates the viscosity behavior of nanofluid utilizing an ANN modeling approach. • The objective is to develop an accurate predictive model for viscosity based on three input parameters. • Experimental data obtained from rheological measurements are used to train and validate the ANN model. • The design of the network involves selecting appropriate architecture, activation functions, and training algorithms. • The developed ANN model offers a reliable and efficient means of estimating the viscosity of nanofluid. [ABSTRACT FROM AUTHOR]

Today, carbon nanotubes are involved in many medical types of research, such as biosensors and drug delivery. These nanotubes do not pose a problem for the body regarding toxicity to body cells and triggering the immune system. Nanotubes have also been proven to increase solubility and the possibility of targeted drug delivery. This study used molecular dynamics simulation to examine the nano-pumping process of the C 20 molecule in carbon nanotubes at the different electric fields and atomic defects. The process of C 20 molecule nano-pumping was examined by examining the changes in kinetic energy, potential energy, entropy, stress, temperature, and internal energy changes. In the following, the stress on the atomic structure was calculated. For this purpose, constant electric fields with the magnitudes of 0.01, 0.02, 0.03, 0.05, and 0.1 V/Å are used for the atomic structure. The results show that the nano-pumping time of the C 20 molecule in the carbon nanotubes increases by increasing the electric field magnitude. The results also revealed that the kinetic energy in the structure decreased by increasing the electric fields, and the potential energy increased. As the potential energy increased in the atomic structure, the stability increased. Therefore, it is expected that the C 20 molecule nano-pumping time will increase. The following examined the effect of atomic defects in an electric field with a magnitude of 0.01 V/Å. For this purpose, the atomic defects with magnitudes of 1 %, 2 %, 3 %, and 4 % were used for carbon nanotubes. The results revealed that increasing the atomic defects increased the C 20 molecule nano-pumping time. Furthermore, the stress on the structure increased by increasing the atomic defects. [Display omitted] • This study investigates the nano-pumping process of the C 20 molecule in a carbon NT. • The C 20 molecule nano-pumping time in the carbon NT increases with the increase of the EF magnitude. • As the PE increases in the atomic structure, the stability increases. • Effect of AD in the presence of an EF with a magnitude of 0.001 eV is investigated. • The stress on the structure increases with the increase of ADs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Molecular Dynamics approach is used for nanochannel-peptide system simulation. • Various parameters were reported for t = 30 ns. • Our simulation results showthe atomic stability in the presence of H 2 O molecules. • The peptide absorption ratio inside the MD box reaches a 78% value. • Results show appropriate behavior of metallic nanochannel with rectangular roughness. Peptides result from partial hydrolysis of protein polypeptide chains. These atomic structures are the main section of various protein compounds. So, the adsorption process of these structures can be used in various medical applications. The small peptide structure is absorbed using a platinum nanochannel with cubic roughness in an aqueous environment in the present computational examination. Technically, the simulation of the nanochannel- peptide system is done using the Molecular Dynamics (MD) method. The different atoms' interactions in our systems are defined by DREIDING/Universal Force-Field (UFF), TIP3P, and Embedded Atom Model (EAM). Temperature, total energy (TE), Radial Distribution Function (RDF), profiles of density/velocity/temperature, absorption ratio, interaction energy, and volume were presented for t = 30 ns in order to provide a physical description of the peptide adsorption process. Our simulation results show the atomic stability of P-nanochannel system in the attendance of H 2 O molecules. Moreover, peptide absorption ratio inside the MD box reached a 78 % value. This result shows the appropriate behavior of a metallic nanochannel with rectangular roughness to adsorption of various protein-based structures, such as Ps for medical aims. [ABSTRACT FROM AUTHOR]

[Display omitted] • Molecular Dynamics approach is used for nanochannel-peptide system simulation. • Various parameters were reported for t = 30 ns. • Our simulation results showthe atomic stability in the presence of H 2 O molecules. • The peptide absorption ratio inside the MD box reaches a 78% value. • Results show appropriate behavior of metallic nanochannel with rectangular roughness. Peptides result from partial hydrolysis of protein polypeptide chains. These atomic structures are the main section of various protein compounds. So, the adsorption process of these structures can be used in various medical applications. The small peptide structure is absorbed using a platinum nanochannel with cubic roughness in an aqueous environment in the present computational examination. Technically, the simulation of the nanochannel- peptide system is done using the Molecular Dynamics (MD) method. The different atoms' interactions in our systems are defined by DREIDING/Universal Force-Field (UFF), TIP3P, and Embedded Atom Model (EAM). Temperature, total energy (TE), Radial Distribution Function (RDF), profiles of density/velocity/temperature, absorption ratio, interaction energy, and volume were presented for t = 30 ns in order to provide a physical description of the peptide adsorption process. Our simulation results show the atomic stability of P-nanochannel system in the attendance of H 2 O molecules. Moreover, peptide absorption ratio inside the MD box reached a 78 % value. This result shows the appropriate behavior of a metallic nanochannel with rectangular roughness to adsorption of various protein-based structures, such as Ps for medical aims. [ABSTRACT FROM AUTHOR]