Crystal growth and reflectivity studies of Zn1-xMnxTe crystals

Single crystals of Zn_1-xMn_xTe were prepared by vertical Bridgman crystal growth method for different concentrations of Mn. Chemical analysis and reflectivity studies were carried out for compositional and band structure properties. Microscopic variation in composition between starting and end compounds was observed from EDAX analysis. Linear dependence of fundamental absorption edgeE ₀as a function of Mn concentration (x) was expressed in terms of a straight line fit and a shift in E₀ towards higher energy was observed in reflectivity spectra of Zn_1-xMn_xTe.     

Crosslinkable coupling agents: Synthesis and use for modification of interfaces in polymer blends

A novel coupling agent containing 2-oxazoline and 2-oxazinone as well as hydrosilane moieties has been prepared by hydrosilylation of the corresponding allyl ether containing precursor with a methylhydrosiloxane-dimethylsiloxane copolymer. This hydrosiloxane containing coupling agent, termed as SCA, was characterized by ¹H NMR and its crosslinkability was proven by DSC. SCA was used for the modification of the interfaces in heterogeneous polymer blends. In a model blend system based on mono-carboxylic acid terminated polystyrene (PS-COOH) and mono-amino terminated poly(methyl methacrylate) (PMMA-NH₂) the 2-oxazoline and 2-oxazinone units of SCA can selectively react with the carboxylic groups or amino groups, respectively. The remaining hydrosilane units partially crosslink under the used mixing conditions.The morphology of the three-component blends prepared by melt mixing was evaluated. SCA is immiscible with the polymers and forms its own phase. The expected location of the SCA at the interface between the polymers was proven only in an annealed, strongly phase separated blend. Overall the effect of the compatibilizer on the morphology is very small. Neither the domain size nor the composition for phase inversion are significantly affected in this blend system by the presence of SCA.     

Hall effects on magnetohydrodynamic rotating flow through porous medium in a parallel plate channel with various oscillations of pressure gradient

We explored the unsteady flow of an incompressible electrically conducting viscous fluid in a gyratory porous medium with a changeable pressure gradient by taking Hall currents into account. The governing equations are then solved analytically with the help of the Laplace transforms methodology. It is regarded as three dissimilar cases, namely, an impulsive change, cosine as well as sine oscillations of the pressure gradient. The physical significances of different dimensionless parameters on velocity distributions are explored analytically and computationally. It is observed that a thin boundary layer is formed near the plate of the channel and the thicknesses of the layer increase with the increase in either the Hall parameter or Reynolds number while it decreases with an increase in Hartmann number. It is interesting to note that the rotation and Lorentz forces are having noteworthy effects on velocity profiles with pressure gradient and Hall currents.     

Hall and ion-slip effects on steady MHD free convective flow through a porous medium in a vertical microchannel

We have considered the steady fully developed magnetohydrodynamic free convection flow through a porous medium in a microchannel bounded by two infinite vertical parallel plates due to asymmetric heating of plates taking Hall and ion-slip effects into account. Effects of velocity slip and temperature jump have been considered on the microchannel surfaces, and the exact solutions have been obtained for momentum and energy equations under relevant boundary conditions. The influence of governing parameters on flow formation is discussed with the aid of graphs. The significant result from the study is that an increase in the value of rarefaction parameter leads to enhancement in volume flow rate. Furthermore, it is evident that the volume flow rate is found to be an increasing function of the Hall current parameter.     

Heat and mass transfer in MHD boundary layer flow of a second-grade fluid past an infinite vertical permeable surface

Heat and mass transfer of non-Newtonian fluids is increasingly being studied by researchers due to its applications in many branches of science and engineering, such as metallurgical processes, polymer extrusion, glass blowing, crystal growing, and so forth. The present work is mainly concerned with the unsteady laminar magnetohydrodynamic flow of a heat-generating or absorbing second-grade fluid past an infinite vertical porous plate. The nondimensional governing equations are solved for the best analytical solution. Results for various flow characteristics are presented through graphs and tables delineating the effect of various parameters characterizing the flow. For engineering interest, the shear stresses, Nusselt number, and Sherwood number are computed and exchanged of views with reference to the important parameters. Our analysis explored that the influences of a chemical reaction and fluid oscillations reduced the concentration distribution in the entire liquid region. The rotation effect decreases the shear stress, whereas it is augmented through an increase in the permeability of porous medium and second-grade fluid parameters' impact.     

Thermal desalination of ballast water using onboard waste heat in marine industry

Ballast water management is a national and international issue in the shipping industry because of potential ecological hazards caused by the release of ballast water into the marine environment. Although many international standards have been implemented in recent years, technological and practical considerations make the ballast water treatment a major challenge for many shipping companies. In this paper, a novel concept of utilizing ballast water as source water for a multieffect desalination process driven by onboard waste heat to meet the freshwater supply needs is proposed with theoretical analysis and practical considerations. A main engine with a capacity of 7500 kW in a cruise ship can serve as a potential waste heat source for water desalination of 1000 m³/d, which can provide for freshwater needs of 2000 to 4000 ship occupants. This scenario presents an attractive alternative to ballast water management and treatment as well as reducing the nonrenewable energy footprint of onboard water supplies in marine industry.     

Optimal GLCM combined FCM segmentation algorithm for detection of kidney cysts and tumor

Multimedia Tools and Applications - In this document, we employed an efficient Optimal GLCM attribute related FCM segmentation algorithm which is used to categorize the kidney cysts and tumor from...     

Heat transport on steady MHD flow of copper and alumina nanofluids past a stretching porous surface

An attempt is made to investigate the steady magnetohydrodynamic convective flow of the viscous nanofluid due to a permeable exponentially stretching porous surface. Water is used as a traditional fluid while nanoparticles include copper and alumina. The fluid is electrically conducting, subject to an applied magnetic field with a constant strength. Convective type boundary conditions are employed in modeling the heat transfer process. The nonlinear partial differential equations governing the flow are reduced to an ordinary differential equation by similarity transformations and then solved using the Runge‐Kutta fourth‐order method. A parametric study of the physical parameters is made, and a representative set of numerical results for the velocity and temperature, as well as local shear stress and local Nusselt number, is presented graphically. Hartman number increase diminishes the velocity and has the contrary result in the subjective sense for the mass transfer parameter. An increase in the Prandtl number Pr lessens the temperature and thickness of the thermal boundary layer. The main conclusions have been indicated.     

Optimization of wet microalgal FAME production from Nannochloropsis sp. under the synergistic microwave and ultrasound effect

The synergistic effect of microwave and ultrasound irradiations was evaluated for biodiesel production from microalgae biomass (Nannochloropsis sp.) as raw material. A response surface methodology technique based on central composite design was used to understand the process parametric interdependence and optimize the process reaction variables. Reaction kinetics of algal fatty acid methyl ester (FAME) production was also studied. The optimum reaction conditions were determined as wet algal biomass to methanol ratio of 20 g to 30 mL, 1 wt% catalyst concentration, and 7‐minute reaction time at 140 W of microwave power and 140 W of ultrasound power. The estimated activation energy was 17,298 J/mol^?1 K^?1 for a first‐order reaction kinetics. This study revealed that microwave energy dissipation at a low rate of 140 W combined with 140 W of ultrasound intensity is adequate to produce FAMEs at a maximum yield of 48.2%. Results from this optimization study suggest that a more detailed and mechanistic energy optimization study is critical to increase the FAME yield and maximize energy benefits.