Analysis of exergy loss vs heat transfer rate for Rayleigh–Bénard convection of various fluids in enclosures with curved walls

The investigation of entropy generation is highly desirable for the optimization of the thermal systems to avoid larger energy wastage and ensure higher heat transfer rate. The numerical investigation of natural convection within enclosures with the concave and convex horizontal walls involving the Rayleigh–Bénard heating is performed via entropy generation approach. The spatial distributions of the temperature (θ), fluid flow (ψ), entropy generation due to heat transfer and fluid friction (S_θ and S_ψ) are discussed extensively for various Rayleigh numbers and Prandtl numbers involving various wall curvatures. A number of complex patterns of spatial distributions of fluid flow and temperature for cavities with concave or convex isothermal walls (top and bottom) have been obtained. The zones of high entropy generation for temperature and fluid flow are detected within cavities with concave and convex horizontal walls. The optimal situation involves the high heat transfer rate with moderate or low entropy generation. Overall, case 3 (highly concave) is found to be optimal over cases 1 and 2 (concave) and cases 1–3 (convex) for all Pr and Ra.     

Bénard-Marangoni convection in two thin immiscible liquid layers with a uniform magnetic field

Summary The effect of a uniform magnetic field on Bénard-Marangoni convection in a shallow cavity, with differentially heated side walls, filld with two viscous, immiscible, incompressible an electrically conducting fluids is studied in the presence of a buoyancy force. The fluid-fluid interface and the free surface are assumed to be flat, and the driving forces for the flow are the thermocapillary and the buoyancy forces. Closed-form solutions, under thin layer approximation neglecting the side wall effects, are obtained for the stream function and the temperature. The solutions are obtained in various limiting cases, namely: absence of buoyancy force, absence of thermocapillary force and absence of magnetic field, and they coincide with the results existing in the literature. The velocity is calculated, and the resulting cell patterns are discussed for different values of , the ratio of the temperature gradients of surface tension at the interface and the free surface and the Hartmann number. There exist four different flow regimes depending on the values of but with reduced convection compared to the non-magnetic case for Marangoni convection. It is observed that it is possible to control the convection in the lower layer by a suitable choice of the magnetic field.     

New insight into the mechanism of formation of dual actives loaded multilayered polymeric particles and their application in food preservation

This study provides an insight about the mechanism of formation of tri-layered (instead of bilayers) particles originated from two biodegradable polymers by emulsion solvent evaporation method. It was also demonstrated how layer configurations of tri-layered particles composed of poly(l -lactide) (PLLA) and poly(d ,l -lactide-co-glycolide) (PLGA), can be changed from kinetically trapped to thermodynamically favorable structures (dictated by spreading coefficient theory) by tweaking several solution parameters. Layer switching, core, and shell thickness manipulation can also be achieved. Interestingly, among the various configurations, tri-layered particles made with PLGA of intermediate viscosity and PLLA of high viscosity were found to provide controlled and sustainable release profiles for dual actives such as antibacterial (benzoic acid) and antioxidant (tocopherol) with appreciably high release rates. The dual activity of these particles was tested by incorporating them in chicken broth medium and found to provide excellent antibacterial as well as antioxidant activity for extended period of time (>20 days). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48009.     

Synthesis and characterization of Sr2+ and Mg2+ doped LaGaO3 by co-precipitation method followed by hydrothermal treatment for solid oxide fuel cell applications

In the present study, LSGM (La_0.8Sr_0.2Ga_0.8Mg_0.2O_2.8) powder has been synthesized using precipitation route followed by hydrothermal treatment. Quantitative phase analyses of different powders, have been done by Rietveld analyses of the XRD data and they reveal formation of single phase orthorhombic LSGM at 1400 °C, 8 h. Morphology of the calcined powder and microstructure of the sintered pellets are observed by transmission electron microscope (TEM) and scanning electron microscope (SEM), respectively. Thermal analysis has been carried out to find out the thermal expansion co-efficient. Successive electrical characterization of the 99% dense sintered pellet has been done by impedance spectroscopic analysis. The diffused semicircles observed in the Nyquist plots have been simulated as (RQ)(RQ) circuit and the total ionic conductivity obtained is found to be the highest for LSGM synthesized by similar routes.     

Change in Orientation of Polyacrylic Acid and Chitosan Networks by Imprintment of Gold Nanoparticles

ABSTRACT

Herein, gold nanoparticles (Au Nps) imprinted polyacrylic acid/chitosan (PAA/CS) nanocomposite hydrogels are designed by in situ polymerization technique. The change in crystallite size and d-spacing is established from X-ray diffraction study. It is interesting to notice that the layered morphology of PAA/CS/Au nanocomposite hydrogel is achieved from field emission scanning electron microscopy due to entanglement of polymeric chains by imprintment of Au Nps. The orientations of polymeric chains reveal the enhancement in pH-responsive swelling percentage and prolong water holding capacity of PAA/CS/Au nanocomposites. Biodegradation of the as-synthesized material is studied from which the antimicrobial activity of Au Nps is predicted.     

Effect of fin type baffle on the particle hydrodynamics,separation and misplacement in a liquid solid fluidized bed separator

Use of fluidization phenomenon is increasing day by day in the mineral beneficiation. Owing to the physical properties of the mineral particles, misplacement happens during the segregation. The present study aims at understanding the effect of fin type vertical baffle along with parameters such as superficial velocity, overflow height, feed composition and Mean Particle Size Ratio (MPSR) on the particle misplacement and separation in a liquid solid fluidized bed separator. The particle misplacement was evaluated quantitatively using “Misplacement Index”. It was found that the fin type vertical baffles have negligible or no effect on the particle misplacement. Moreover, change in the superficial velocity, overflow height, feed composition and MPSR substantially affects the particle misplacement. Further, there exists a critical feed composition where the misplacement is low. In addition to this, there also exists a critical MPSR where the fluidized bed operates in a completely mixed state and the point could be considered as the starting of the layer inversion.     

Delineation and mapping of coal mine fire using remote sensing data – a review

Various countries around the globe face numerous hazards due to the burning of coal on the surface as well as below ground. Countries like China, India, United States of America (USA), Australia, Indonesia, and many other countries have reported the burning of coal fires, and thus it is the urgent need to control the coal fire propagation to prevent the loss of energy resources. Coal is a fossil fuel that has a tendency to catch fire for many reasons; spontaneous combustion being the most frequent reasons for its burning. Other factors leading to coal fire include forest fires close to coal seams, natural hazards, old mining techniques, and external heat sources. The review work demonstrates the application of various satellite data in fire detection and mapping. The literature reveals that remote sensing plays an important role in facilitating quick and complete delineation of coal mine fires. Many algorithms have been developed around the world for fire detection from different satellite data. A comprehensive demonstration of different algorithms along with their merits and demerits are outlined. Comparative performances of the different algorithms with their case studies are also explained. It can be inferred from the various literature that it is very difficult to select a particular sensor algorithm for generating global fire products. Suggestions are given to further explore the possibility of improvement of fire detection algorithms.     

ILipo-PseAAC: Identification of Lipoylation Sites Using Statistical Moments and General PseAAC

Lysine Lipoylation is a protective and conserved Post Translational Modification (PTM) in proteomics research like prokaryotes and eukaryotes. It is connected with many biological processes and closely linked with many metabolic diseases. To develop a perfect and accurate classification model for identifying lipoylation sites at the protein level, the computational methods and several other factors play a key role in this purpose. Usually, most of the techniques and different traditional experimental models have a very high cost. They are time-consuming; so, it is required to construct a predictor model to extract lysine lipoylation sites. This study proposes a model that could predict lysine lipoylation sites with the help of a classification method known as Artificial Neural Network (ANN). The ANN algorithm deals with the noise problem and imbalance classification in lipoylation sites dataset samples. As the result shows in ten-fold cross-validation, a brilliant performance is achieved through the predictor model with an accuracy of 99.88%, and also achieved 0.9976 as the highest value of MCC. So, the predictor model is a very useful and helpful tool for lipoylation sites prediction. Some of the residues around lysine lipoylation sites play a vital part in prediction, as demonstrated during feature analysis. The wonderful results reported through the evaluation and prediction of this model can provide an informative and relative explanation for lipoylation and its molecular mechanisms.     

Correlations for critical fluidization velocity and maximum bed pressure drop for heterogeneous binary mixture of irregular particles in gas–solid tapered fluidized beds

The tapered fluidized bed is a remedial measure for certain drawbacks of the gas–solid system, by the fact that a velocity gradient exists along the axial direction of the bed with increase in cross-sectional area. To study the dynamic characteristics of heterogeneous binary mixture of irregular particles, several experiments have been carried out with varying tapered angles and composition of the mixtures with various particles. The tapered angle of the bed has been found to affect the characteristics of the bed. Models based on dimensional analysis have been proposed to predict the critical fluidization velocity and maximum bed pressure drop for gas–solid tapered fluidized beds. Experimental values of critical fluidization velocity and maximum bed pressure drop compare well with that predicted by the proposed models and the average absolute errors are well within 15%.     

Characteristic spectral features of the polarized fluorescence of human breast cancer in the wavelet domain

Wavelet transform of polarized fluorescence spectra of human breast tissues is found to localize spectral features that can reliably differentiate normal and malignant tissue types. The intensity differences of parallel and perpendicularly polarized fluorescence spectra are subjected to investigation, since they are relatively free of diffusive background. A number of parameters, capturing spectral variations and subtle changes in the diseased tissues in the visible wavelength regime, are clearly identifiable in the wavelet domain. These manifest both in the average low-pass and high frequency high-pass wavelet coefficients.