The influence of geometrical shapes of stenosis on the blood flow in stenosed artery

The present work was carried out to investigate the blood flow behavior and the severity of blockage caused in the arterial passage due to the different geometries such as elliptical, trapezium and triangular shapes of stenosis. The study was conducted with respect to various sizes of stenosis in terms of 70%, 80% and 90% area blockage of the arterial blood flow. The study was carried out numerically with the help of advance computational fluid dynamic software. It was found that the shape of the stenosis plays an important role in overall pressure drop across the blockage region of artery. The highest level of pressure drop was observed for trapezoidal shape of stenosis followed by elliptical and then by triangular shaped stenosis. The wall shear stress across the stenosis is great for trapezoidal shape followed by triangular and elliptical stenosis for same blockage area in the artery

Flow control in microfluidics devices: electro-osmotic Couette flow with joule heating effect

Purpose – Joule heating effect is a pervasive phenomenon in electro-osmotic flow because of the applied electric field and fluid electrical resistivity across the microchannels. Its effect in electro-osmotic flow field is an important mechanism to control the flow inside the microchannels and it includes numerous applications. Design/methodology/approach – This research article details the numerical investigation on alterations in the profile of stream wise velocity of simple Couette-electroosmotic flow and pressure driven electro-osmotic Couette flow by the dynamic viscosity variations happened due to the Joule heating effect throughout the dielectric fluid usually observed in various microfluidic devices. Findings – The advantages of the Joule heating effect are not only to control the velocity in microchannels but also to act as an active method to enhance the mixing efficiency. The results of numerical investigations reveal that the thermal field due to Joule heating effect causes considerable variation of dynamic viscosity across the microchannel to initiate a shear flow when EDL (Electrical Double Layer) thickness is increased and is being varied across the channel. Originality/value – This research work suggest how joule heating can be used as en effective mechanism for flow control in microfluidic devices

Numerical analysis of heat transfer in human head

An investigation of heat transfer in human head is carried out by using finite element method. The head is modeled with different tissues having varying physical properties. The current work is focused to simulate the effect of various physical and geometrical parameters such as ambient temperature, heat transfer coefficient and variation in the thickness of different tissue layers of human head. The effect of presence of hair on human head is also investigated. It is found that the deep brain temperature remains almost constant whereas a small variation occurs in the other layers with respect to varying environmental and geometrical parameters. © 2019, KSME & Springer

Biodiesel Production by Direct Transesterification Process via Sequential Use of Acid–Base Catalysis

It is a well-known fact that energy consumption is rapidly increasing due to population growth, higher standard of living and increased production. A significant amount of energy resources are being consumed by the transportation sector leading to fast depletion of fossil fuels and environmental pollution. Biodiesel is one of the technically and economically feasible options to tackle the aforesaid problems. Biodiesel seems to be a replacement to the diesel and can be commonly produced by two-step esterification–transesterification process. In the current research, single-step process of direct transesterification method is developed and is compared with conventional two-step esterification–transesterification method. The fuel properties of biodiesel produced by these two methods have been studied. The results revealed that fuel properties of biodiesel like calorific value, kinematic viscosity, flash point, density, acid value remained similar in both methods. However, the new method developed is superior with respect to reduced reaction time, lower acid value and increased biodiesel yield. The acid value of biodiesel obtained by single-step and two-step method was found to be 0.1 and 0.25 mg KOH/g, respectively. The new method was able to reduce the reaction time from 5 to 2 h. Yield of biodiesel was increased from 2 to 5% indicating advantages of new method compared to two-step conventional method

Optimization of subtilisin production from Bacillus subtilis strain ZK3 and biological and molecular characterization of synthesized subtilisin capped nanoparticles

The increase and dissemination of multi-drug resistant bacteria have presented a major healthcare challenge, making bacterial infections a significant concern. The present research contributes towards the production of bioactive subtilisin from a marine soil isolate Bacillus subtilis strain ZK3. Custard apple seed powder (raw carbon) and mustard oil cake (raw nitrogen) sources showed a pronounced effect on subtilisin production. A 7.67-fold enhancement in the production was evidenced after optimization with central composite design-response surface methodology. Subtilisin capped silver (AgNP) and zinc oxide (ZnONP) nanoparticles were synthesized and characterized by UV–Visible spectroscopy. Subtilisin and its respective nanoparticles revealed significant biological properties such as, antibacterial activity against all tested pathogenic strains with potential against Escherichia coli and Pseudomonas aeruginosa. Prospective antioxidant behavior of subtilisin, AgNP and ZnONP was evidenced through radical scavenging assays with ABTS and DPPH. Subtilisin, AgNP and ZnONP revealed cytotoxic effect against cancerous breast cell lines MCF-7 with IC50of 83.48, 3.62 and 7.57 µg/mL respectively. Characterizations of nanoparticles were carried out by Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray, X-ray diffraction, thermogravimetric analysis and atomic force microscopy analysis to elucidate the structure, surface and thermostability properties. The study proposes the potential therapeutic applications of subtilisin and its nanoparticles, a way forward for further exploration in the field of healthcare

Molecular dynamics and simulation analysis against superoxide dismutase (SOD) target of Micrococcus luteus with secondary metabolites from Bacillus licheniformis recognized by genome mining approach

Micrococcus luteus, also known as M. luteus, is a bacterium that inhabits mucous membranes, human skin, and various environmental sources. It is commonly linked to infections, especially among individuals who have compromised immune systems. M. luteus is capable of synthesizing the enzyme superoxide dismutase (SOD) as a component of its protective response to reactive oxygen species (ROS). This enzyme serves as a promising target for drug development in various diseases. The current study utilized a subtractive genomics approach to identify potential therapeutic targets from M. luteus. Additionally, genome mining was employed to identify and characterize the biosynthetic gene clusters (BGCs) responsible for the production of secondary metabolites in Bacillus licheniformis (B. licheniformis), a bacterium known for its production of therapeutically relevant secondary metabolites. Subtractive genomics resulted in identification of important extracellular protein SOD as a drug target that plays a crucial role in shielding cells from damage caused by ROS. Genome mining resulted in identification of five potential ligands (secondary metabolites) from B. licheniformis such as, Bacillibactin (BAC), Paenibactin (PAE), Fengycin (FEN), Surfactin (SUR) and Lichenysin (LIC). Molecular docking was used to predict and analyze the binding interactions between these five ligands and target protein SOD. The resulting protein–ligand complexes were further analyzed for their motions and interactions of atoms and molecules over 250 ns using molecular dynamics (MD) simulation analysis. The analysis of MD simulations suggests, Bacillibactin as the probable candidate to arrest the activities of SOD. All the five compounds reported in this study were found to act by directly/indirectly interacting with ROS molecules, such as superoxide radicals (O2–) and hydrogen peroxide (H2O2), and transforming them into less reactive species. This antioxidant activity contributes to its protective effects against oxidative stress-induced damage in cells making them likely candidate for various applications, including in the development of antioxidant-based therapies, nutraceuticals, and functional foods

Environmental and economic issues for renewable production of bio-jet fuel: A global prospective

Given how quickly the aviation sector is growing, it is crucial to find sustainable ways to supply the demand. Modern technological developments and the creation of alternative jet fuels are crucial elements that could help eliminate greenhouse gases (GHGs) like CO2 emissions. Traditional jet fuel produces a sizable amount of GHG emissions, which has raised concern on a global scale. Compared to conventional jet fuel, biofuel is thought to be more renewable and less polluting. Biojet fuels might work as an effective substitute. The varieties of bio jet fuel, manufacturing procedures (including alcohol-to-jet, oil-to-jet, syngas-to-jet, and sugar-to-jet ways), existing regulations, and the effects of bio jet fuels on the environment and the economy are all covered in length in this overview. These are the techniques that are most frequently used to create bio-jet fuel from both edible and inedible feedstock. The main conclusions of this review indicate that the most popular method for producing biofuel is hydrogenated esters and fatty acids (HEFA). The Fischer-Tropsch (FT) approaches cost more to install even though they produce fewer GHGs. Environmentally beneficial and technologically advanced, second-generation biofuels are a great choice. It has been revealed that jatropha is a crop that produces a lot of energy. The price of feedstock and the lack of bio-jet fuel are the two biggest obstacles to substituting conventional fuel. To increase the power and quality of energy, further in-depth research on optimal feedstocks is necessary. In order to address the needs of both commercial and military aircraft, biomass jet fuel has a lot of potential to replace conventional jet fuel. High yield should be one of the properties of the feedstock without affecting food production

Synthesis and characterization of flyash reinforced polymer composites developed by Fused Filament Fabrication

Fused filament fabrication (FFF) has seen an upsurge in its utilization towards development of tailored made materials of polymer base. The advancement and diversity in fabricating the polymer composite parts by using FFF has seen the embracement of this technology in wider aspects, ranging from automotive, aerospace, construction and has marched towards day to day requirements. This research article focuses on development of polymer composite; by using flyash (FA), an industrial waste produced during coal combustion, as reinforcement in Acrylonitrile butadiene styrene (ABS) matrix, to study the physical and mechanical properties. FA, which is primarily made up of metal oxides, plays an imperative role as reinforcement. Easily and abundantly available, FA is being used in several applications to reduce the landfills utilization and also helps the environment. In this study FA was added as reinforcement in 5 and 10 wt. % respectively to ABS matrix and was developed into filament of 1.75 mm diameter. The developed ABS + FA polymer composite using FFF, were analyzed for physical and mechanical properties as per American Society for Testing and Materials (ASTM) standards. Microstructure studies were carried out for the developed composite to understand their behavior in enhancing the dimensional accuracy and tensile strength with incremental addition of FA up to 10 wt%. Tensile strength was enhanced by 28.19% and 36.13% for ABS + 5wt. % FA and ABS + 10wt. % FA respectively. Dimensional stability was also enhanced. Similarly, surface roughness analysis was carried out and it was observed to reduce with addition of FA. The surface roughness measurements provided suitable results of decrement by 9.64% and 14.6% for ABS + 5wt. % FA and ABS + 10wt. % FA respectively. Overall, the usage of FA along with FFF, has paved a path in sustainable and green technology in manufacturing

Utilization of additives in biodiesel blends for improving the diesel engine performance and minimizing emissions through a modified Taguchi approach

Biodiesel from Jatropha oil is produced through catalyzed homogeneous transesterification. Hydrogen peroxide (H2O2) is considered as additive. Blends of Jatropha considered in the present study are 60% diesel, (40-A)% biodiesel and A% additive, varying A from 0 to 10. Identifying optimal input variables (such as additive volume percentage, injection pressure, and load) is important for improving the engine performance and reducing emissions. Air-fuel ratio; brake specific fuel consumption (BSFC); and brake thermal efficiency (BTE) are the engine performance characteristics. Carbon monoxide (CO); carbon dioxide (CO2); exhaust gas temperature (EGT); nitrogen oxide (NOx); and smoke opacity are the emission characteristics. 27 experiments need to be performed for the assigned 3 levels and 3 input variables. The Taguchi's L9 orthogonal array (OA) is chosen to perform only 9 experiments to obtain the optimal solution. The expected range of performance characteristics and emissions was obtained following a modified Taguchi approach. Empirical relationships are developed and verified through engine performance and emission characteristics

Effects of engine variables and heat transfer on the performance of biodiesel fueled IC engines

These days internal combustion engines are the major source of transportation. They run mainly on fossil fuels which are depleting day by day not only that they cause pollution which endangers human life and creates environmental problems. Of late biodiesel has emerged as a better alternative fuel for internal combustion engines due to its comparable properties with that of fossil fuels. Today's automobiles require economy of operation, high power output and last but not the least, reduction in greenhouse gases emitted by the vehicles. Such specific demands have compelled the researchers not only to focus on the parameters affecting the performance but also on emission of the internal combustion engines. This paper reviews the effects of different engine variables such as compression ratio, load and speed, fuel injection parameters, air swirl, piston design on the performance of engine. Special attention has been paid on the future automotive engines which would be significantly governed by electronic systems. According to us the same technology can also be employed in analyzing engines running on biofuels. (C) 2015 Elsevier Ltd. All rights reserved