Analysis of non-newtonian magnetic casson blood flow in an inclined stenosed artery using caputo-fabrizio fractional derivatives

Background and Objective: Arterial diseases would lead to several serious disorders in the cardiovascu- lar system such as atherosclerosis. These disorders are mainly caused by the presence of fatty deposits, cholesterol and lipoproteins inside blood vessel. This paper deals with the analysis of non-Newtonian magnetic blood flow in an inclined stenosed artery. Methods: The Casson fluid was used to model the blood that flows under the influences of uniformly dis- tributed magnetic field and oscillating pressure gradient. The governing fractional differential equations were expressed using the Caputo Fabrizio fractional derivative without singular kernel. Results: The analytical solutions of velocities for non-Newtonian model were then calculated by means of Laplace and finite Hankel transforms. These velocities were then presented graphically. The result shows that the velocity increases with respect to Reynolds number and Casson parameter, while decreases when Hartmann number increases. Conclusions: Casson blood was treated as the non-Newtonian fluid. The MHD blood flow was accelerated by pressure gradient. These findings are beneficial for studying atherosclerosis therapy, the diagnosis and therapeutic treatment of some medical problems

Addition of Graphite Filler to Enhance Electrical, Morphological, Thermal, and Mechanical Properties in Poly (Ethylene Terephthalate): Experimental Characterization and Material Modeling

Poly(ethylene terephthalate)/graphite (PET/G) micro-composites were fabricated by the melt compounding method using a minilab extruder. The carbon fillers were found to act as nucleating agents for the PET matrix and hence accelerated crystallization and increased the degree of crystallinity. TGA showed that carbon fillers improved the resistance to thermal and thermo-oxidative degradation under both air and nitrogen atmospheres. However, a poor agreement was observed at higher loadings of the filler where the composites displayed reduced reinforcement efficiency. The results demonstrate that the addition of graphite at loading >14.5 wt.% made electrically conductive composites. It was calculated that the electric conductivities of PET/graphite micro-composites were enhanced, above the percolation threshold values by two orders of magnitudes compared to the PET matrix. The minimum value of conductivity required to avoid electrostatic charge application of an insulating polymer was achieved, just above the threshold values. The addition of graphite also improved thermal stability of PET, accelerated its crystallization process and increased the degree of crystallinity. Microscopic results exhibit no indication of aggregations at 2 wt.% graphite, whereas more agglomeration and rolling up could be seen as the graphite content was increased in the PET matrix (in particular, above the percolation threshold value). Furthermore, based on the mechanical experimental characterization of the PET/graphite micro-composites, a large deformation-based mathematical model is proposed for material behavior predictions. The model fits well the experimental data and predicts other mechanical data that are not included in the parameter identification

H2 Production from Catalytic Methane Decomposition Using Fe/x-ZrO2 and Fe-Ni/(x-ZrO2) (x = 0, La2O3, WO3) Catalysts

An environmentally-benign way of producing hydrogen is methane decomposition. This study focused on methane decomposition using Fe and Fe-Ni catalysts, which were dispersed over different supports by the wet-impregnation method. We observed the effect of modifying ZrO2 with La2O3 and WO3 in terms of H2 yield and carbon deposits. The modification led to a higher H2 yield in all cases and WO3-modified support gave the highest yield of about 90% and was stable throughout the reaction period. The reaction conditions were at 1 atm, 800 °C, and 4000 mL(hgcat)−1 space velocity. Adding Ni to Fe/x-ZrO2 gave a higher H2 yield and stability for ZrO2 and La2O3 + ZrO2-supported catalysts whose prior performances and stabilities were very poor. Catalyst samples were analyzed by characterization techniques like X-ray diffraction (XRD), nitrogen physisorption, temperature-programmed reduction (TPR), thermo-gravimetric analysis (TGA), and Raman spectroscopy. The phases of iron and the supports were identified using XRD while the BET revealed a significant decrease in the specific surface areas of fresh catalysts relative to supports. A progressive change in Fe’s oxidation state from Fe3+ to Fe0 was observed from the H2-TPR results. The carbon deposits on Fe/ZrO2 and Fe/La2O3 + ZrO2 are mainly amorphous, while Fe/WO3 + ZrO2 and Fe-Ni/x-ZrO2 are characterized by graphitic carbon

Recovery of Sulphur by Modified Claus Process Using Cold Bed Adsorption

A single stage conventional Claus catalytic reactor was modified by adding a cold bed adsorption (CBA) reactor operating in low temperatures in series with the former. Activated alumina catalysts in the form of cylindrical pellets impregnated with a promoter were used for the Claus reaction at low temperatures “(~175°C) to enhance the H2S conversion from 70% in the Claus reactor to more than 99 percent in the modified setup:2HS+SO2=3xSx+2H2O;ΔH=−109.2kJmol;for x=1,where X may vary from 2 to 8 and Sx represents the sulphur species like S2, S3, S4...S8. This has been possible by Operating the CBA reactor at temperatures below the dew point of sulphur in the reaction mixture. Effects of temperature and catalyst bed depth in the CBA reactor indicated that H2S conversion tends toward 100% at a temperature of 175°C, and 12 inch catalyst bed depth would be considered optimum at a conversion of 99.5%. At 15-18 inch bed depth, the increase in H2S conversion is negligible. At the lowest temperature studied (175°C), the exit gases contained only 0.05% (mole) of the acid gases. The catalytic deactivation through the deposited sulphur was not studied but it was predicted that the deactivation of catalysts did not occur as fast as was expected because sulphur partly plays the role of an autocatalyst in the Claus reaction. Catalyst regeneration by simple elimination of the deposited sulphur did not result in full recovery of the activity of the fresh catalyst

A study of heat and mass transfer micropolar fluid flow near the stagnation regions of an object

The main objective of this analysis is to present an unsteady magneto-micropolar fluid throw towards a circular object. An impulsive flow is assumed at a very large distance from object which is known as free stream region. The free stream region is perpendicular to the object in upward direction. Due to this phenomena, body forces are taken in the form of convection. In this problem, the object is assumed to be extremely heated which take us towards two main assumptions: i) assisting flow is taken and opposing flow is neglected and ii) radiation factor appears. The free stream flow is so dominant that it touches all external sides of the object which gives a good mathematical study of the stagnation regions (forward and rare) and the remaining points in which fluid particles touch the object. The different situations are assumed at different angles to analyze the flow, temperature, microrotation and concentration distributions. But our main focus will be rare and forward stagnation points. Heat generation and chemical reaction influence are also studied for such complex formulation. A magnetic field is applied to align these fluid particles motion. The so-called non-similar transformations and boundary layer approximation are used to obtain the very complex highly non-linear partial differential system depending on three independent variables. A second order convergent scheme known as Keller box is implemented to calculate the solution of the system. The results for separation time around the cylinder are calculated in tabular form. Moreover, graphical behavior is examined for forward and rare stagnation points for concentration, microrotation, velocity and temperature distributions. A comparative analysis is executed from previous data for different values of separation time

Influence of entropy generation on hybrid nanoparticles near the lower region of solid sphere

In this paper, entropy generation effect on MHD boundary layer flow of hybrid nano-liquid with non-uniform viscosity near the lower stagnation region of heated sphere is examined. Hybrid nano-liquid is an innovative class of thermal liquids based nanotechnology and essentially it has been validated to enhance the energy conversion process competence. The flow of CH3OH liquid is diluted by adding alloy nanoparticles (a class of alumina) and their oxides are absolutely proficient to deflate the empirical scientific concerns related to quicker thermal transport. Governing PDEs are simplified and renovated into systems of ODEs and numerical solutions are executed by RK-4 based shooting scheme. We have also brought under discussion the impact of distinct substantial physical parameters of problem. A careful analysis discloses that thermal transfer rate of nano-liquid is immensely magnificent as compare to the mono nano-liquid. A close comparison exhibits that the hybrid nanosuspension offers elevated thermal distribution than usual nano-liquids

NiSn nanoparticle-incorporated carbon nanofibers as efficient electrocatalysts for urea oxidation and working anodes in direct urea fuel cells

Synthesis of NiSn alloy nanoparticle-incorporated carbon nanofibers was performed by calcining electrospun mats composed of nickel acetate, tin chloride and poly(vinyl alcohol) under vacuum. The electrochemical measurements indicated that utilization of tin as a co-catalyst could strongly enhance the electrocatalytic activity if its content and calcination temperature were optimized. Typically, the nanofibers prepared from calcination of an electrospun solution containing 15 wt% SnCl2 at 700 °C have a current density almost 9-fold higher than that of pristine nickel-incorporated carbon nanofibers (77 and 9 mA/cm2, respectively) at 30 °C in a 1.0 M urea solution. Furthermore, the current density increases to 175 mA/cm2 at 55 °C for the urea oxidation reaction. Interestingly, the nanofibers prepared from a solution with 10 wt% of co-catalyst precursor show an onset potential of 175 mV (vs. Ag/AgCl) at 55 °C, making this proposed composite an adequate anode material for direct urea fuel cells. Optimization of the co-catalyst content to maximize the generated current density resulted in a Gaussian function peak at 15 wt%. However, studying the influence of the calcination temperature indicated that 850 °C was the optimum temperature because synthesizing the proposed nanofibers at 1000 °C led to a decrease in the graphite content, which dramatically decreased the catalyst activity. Overall, the study opens a new venue for the researchers to exploit tin as effective co-catalyst to enhance the electrocatalytic performance of the nickel-based nanostructures. Moreover, the proposed co-catalyst can be utilized with other functional electrocatalysts to improve their activity toward oxidation of different fuels. Keywords: Urea fuel cell, Urea electrolysis, NiSn carbon nanofibers, Electrospinnin

Engineered nanostructures: A review of their synthesis, characterization and toxic hazard considerations

Research work on the synthesis, designing and characterization of nanostructures has been extensively documented in the last decades. This in-depth documentation not only enabled researchers to understand the relationship between the nanostructure properties, size, shape, and composition but also have given them immense control over their manufacturing. This enhanced knowledge, cemented the switching of academic nanotechnology research into industrial products. However; despite the recent accomplishment in synthesis, characterization and application of the nanostructure materials, a complete knowledge/information of their interactions with biological systems is still not available. Hence, it is difficult to forecast the injurious biological responses of these novel nanostructures to humans, animals, insects and plants. Due to this hesitancy, safety regulatory authorities and general public have raised their concerns to the manufacturing and use of nanostructure-based products. Consequently, it is vital for the researchers to concentrate more on safe designing, manufacturing and characterization of nanostructures before these could meet human and communal needs. This review is taking an overview of the increasing investments in nanotechnology, designing, synthesis and characterization of nanostructures and their in vitro and in vivo toxicities

Magnetic/Polyetherimide-Acrylonitrile Composite Nanofibers for Nickel Ion Removal from Aqueous Solution

In this study, a magnetic/polyetherimide-acrylonitrile composite nanofiber membrane with effective adsorption of nickel ions in an aqueous solution was created using a simple electrospinning method. Iron oxide nanoparticles (NPs) were stirred and ultrasonically dispersed into a polyetherimide-acrylonitrile solution to create a homogenous NPs suspension, which was placed in an electrospinning machine to produce a uniform and smooth nanofiber composite membrane. Nanoparticle incorporation into this membrane was confirmed using scanning electron microscope, energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and NPs aqueous stability from a leaching test. The high adsorption capability of the membrane on nickel ions was attributed to the combination of magnetic NPs, polyetherimide-acrylonitrile matrix, and the nanostructure of the membrane. A membrane containing magnetic NPs demonstrated the maximum adsorption capabilities (102 mg/g) of nickel ions in an aqueous solution. Various kinetic and isotherm models were applied to understand the adsorption behavior, such as pseudo-second-order kinetic and Langmuir isotherm models. A polyetherimide-acrylonitrile composite nanofiber membrane containing magnetic NPs could be used as an environmentally friendly and nontoxic adsorbent for the removal of nickel ions in an aqueous medium due to its ease of preparation and use and stability in aqueous mediums