Cattaneo–Christov double-diffusion model with Stefan blowing effect on copper–water nanofluid flow over a stretching surface

We often encounter many processes where the cooling rate is a key factor in deciding the features of a desired product. Due to increasing demands of controlled cooling systems, an effort is made to theoretically study the effect of volume fraction on mixed convective Cu–water nanofluid flow over a stretching surface with activation energy and thermal radiation. The nonlinear dynamical system is simplified using apt similarity variables and the obtained ordinary differential equations are dealt numerically using Runge–Kutta–Fehlberg method and shooting scheme. The thermal and solutal equations are modeled considering Cattaneo–Christov double-diffusion model. The flow problem is studied considering velocity slip and zero mass flux state at the surface. As a novelty, the present case considers the blowing effect at the surface to study massive species transport during nanofluid flow with Cattaneo–Christov double-diffusion model. The results show that an increase in strength of thermal radiation increases temperature and buoyancy ratio parameter, thereby escalating the skin friction coefficient. When thermal relaxation parameter changes from 0.001 to 0.005, heat transfer coefficient improves by 24.36%. Furthermore, with the change in value of the blowing parameter from 0.1 to 0.1015, the maximum value concentration of nanoparticles that is attained during the flow is increased by 7.15%.     

ANTIOXIDANT AND CALMODULIN-INHIBITORY ACTIVITIES OF PHENOLIC COMPONENTS IN FRUIT WINES AND ITS BIOTECHNOLOGICAL IMPLICATIONS

Fruits are rich sources of anthocyanins, flavonoids and phenols that are important nutraceutical components. Processed products of various fruits such as wines and juices, also contain these nutraceuticals, and have been proposed to be the primary components that provide health-beneficiary effects to the cardiovascular system. In the present study, we have evaluated the antioxidant and calmodulin-inhibitory effects of three fruit wines and a red grape wine to provide a comparison in their nutraceutical properties. Using in vitro systems that generate superoxide radicals and hydroxyl radicals, all the wines and their partially purified phenolic extracts were demonstrated to possess strong superoxide and hydroxyl radical scavenging properties. On the basis of specific phenolic content, the summer cherry, blackberry and blueberry wines were 30-40% more efficient in superoxide radical scavenging than red grape wine. Similarly, blueberry wine demonstrated considerably high hydroxyl radical scavenging efficiency than the other wines. The flavonoid aglycones such as catechin and naringenin, were as efficient or more in scavenging superoxide radicals, as ascorbate. As well, these compounds also scavenged hydroxyl radicals, as or more effectively than melatonin, a known hydroxyl radical scavenger. All the wines had components that inhibited calcium and calmodulin-promoted phosphodiesterase activity, indicating their potential to interfere with the calcium second messenger function. Blueberry, blackberry and red wine components were more effective in the inhibition of calmodulin-promoted phosphodiesterase than those from summer cherry wine. Active oxygen scavenging or calmodulin-inhibitory properties appear to be associated with a variety of wine components that may provide synergistic action than any single components in them. This study paves way for the potential use of fermentation biotechnology to optimize the enzymatic release and levels of nutritionally important phenolic components in fruit wines.     

Design and analysis of various bidirectional 2DPCAs in feature partitioning framework

Multimedia Tools and Applications - In this paper, we present various of bidirectional 2DPCAs in feature partitioning framework. To capture hybrid variations of images with optimal feature...     

Preparation of pH‐sensitive hydrogels by graft polymerization of itaconic acid on tragacanth gum

Graft polymerization of itaconic acid on tragacanth gum (TG) was carried out using potassium persulfate as initiator to develop smart hydrogels for drug delivery systems. The effect of the grafting parameters on the degree of grafting was investigated. The grafting was significantly influenced by the reaction medium, the reaction temperature and the monomer concentration. The monomer dependency of the system was found to be 1.52. The hydrogels were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and X‐ray diffraction. The grafted TG had an amorphous nature and exhibited excellent swelling in water and strong dependence on the pH of the medium. The grafted TG showed pH‐dependent release of ciprofloxacin which offers the possibility of using these materials in colon‐specific drug targeting for human healthcare systems. © 2018 Society of Chemical Industry     

Reactive blends of epoxy resin (DGEBA) crosslinked by anionically polymerized polycaprolactam. II. Mechanical and electrical properties

Various reactive blends of diglycidyl ether of bisphenol A (DGEBA)/polycaprolactam were synthesized by anionic polymerization at 140°C, conducted by sodium hydride catalyst, a strong base, along with N‐acetyl caprolactam as a cocatalyst. The experiments were performed to study the effect of composition on the mechanical and electrical properties of the reactive blends, such as tensile properties, flexural properties, Izod impact strength, Rockwell hardness, and volume resistivity. It was observed that the DGEBA was crosslinked by the polycaprolactam through the rapid reaction of the oxirane group with amide nitrogen. The heat of reaction and heat‐deflection temperature of the reactive blends increased with increasing DGEBA content from 50 to 80 wt %, and increased dramatically above 70 wt % DGEBA content. The mechanical and electrical properties of the reactive blends increased with increasing DGEBA content from 50 to 80 wt %. Substantial increases in these properties were observed above 70 wt % DGEBA content in the reactive blends. SEM studies revealed that the reactive blends show a multiphase system with an increase in the DGEBA content from 50 to 80 wt % as the mixing of the two phases increased. The reactive blend Ep₈₀Ca₂₀, with 80 wt % DGEBA content, resembles a single‐phase system because of better mixing of the two phases; as a result, this reactive blend showed the highest mechanical and electrical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 537–549, 2005     

Hybrid finite element/volume method for shallow water equations

A hybrid numerical scheme based on finite element and finite volume methods is developed to solve shallow water equations. In the recent past, we introduced a series of hybrid methods to solve incompressible low and high Reynolds number flows for single and two‐fluid flow problems. The present work extends the application of hybrid method to shallow water equations. In our hybrid shallow water flow solver, we write the governing equations in non‐conservation form and solve the non‐linear wave equation using finite element method with linear interpolation functions in space. On the other hand, the momentum equation is solved with highly accurate cell‐center finite volume method. Our hybrid numerical scheme is truly a segregated method with primitive variables stored and solved at both node and element centers. To enhance the stability of the hybrid method around discontinuities, we introduce a new shock capturing which will act only around sharp interfaces without sacrificing the accuracy elsewhere. Matrix‐free GMRES iterative solvers are used to solve both the wave and momentum equations in finite element and finite volume schemes. Several test problems are presented to demonstrate the robustness and applicability of the numerical method. Copyright © 2010 John Wiley & Sons, Ltd.     

Bulk Single Crystal‐Like Structural and Magnetic Characteristics of Epitaxial Spinel Ferrite Thin Films with Elimination of Antiphase Boundaries

Spinel ferrite NiFe₂O₄ thin films have been grown on three isostructural substrates, MgAl₂O₄, MgGa₂O₄, and CoGa₂O₄ using pulsed laser deposition. These substrates have lattice mismatches of 3.1%, 0.8%, and 0.2%, respectively, with NiFe₂O₄. As expected, the films grown on MgAl₂O₄ substrate show the presence of the antiphase boundary defects. However, no antiphase boundaries (APBs) are observed for films grown on near‐lattice‐matched substrates MgGa₂O₄ and CoGa₂O₄. This demonstrates that by using isostructural and lattice‐matched substrates, the formation of APBs can be avoided in NiFe₂O₄ thin films. Consequently, static and dynamic magnetic properties comparable with the bulk can be realized. Initial results indicate similar improvements in film quality and magnetic properties due to the elimination of APBs in other members of the spinel ferrite family, such as Fe₃O₄ and CoFe₂O₄, which have similar crystallographic structure and lattice constants as NiFe₂O₄.     

Removal of hexachlorobenzene from soil by electrokinetically enhanced chemical oxidation

This study investigates the feasibility of enhanced electrokinetic Fenton process for the remediation of hexachlorobenzene (HCB) in low permeable soil. Laboratory scale experiments were carried out in two different type of experimental setup to evaluate the influence of electrode positions in the system. Kaolin was artificially contaminated with HCB and treated by electrokinetic Fenton process. beta-Cyclodextrin was used to enhance the solubility of HCB in pore fluid. Results show that the position of electrodes in the system and the way in which Fenton's reagent was added to the system has a significant influence on the treatment efficiency.