Numerical investigation on the hydrodynamics of an LSCFB riser

Analysis of fluid flow in a liquid-solid circulation fluidized bed (LSCFB) is necessary to understand its behavior under different operating parameters. In this work, ample parametric studies have been carried out numerically, which provides a view how an LSCFB operates under different operating parameters, and the numerical model has been validated using the experimental data. This study aims to get an insight of the behavior of LSCFB under different operating parameters, which include solids circulation rate, primary and auxiliary liquid velocity. In addition to this task, numerical modeling has also been carried out to predict the behavior of different particles with different densities upon fluidization in an LSCFB, which resolves the problem of experimentation with a wide spectrum of new particles that might have a wide variety of applications in an LSCFB. LSCFBs always involve high Reynolds number flow and dense solids concentration, which demands for proper modeling of the turbulent flow, liquid-solid interactions and particle-particle interactions. Kinetic theory based on Eulerian-Eulerian two-phase model is used to account for particle interactions and is applied to model the solids viscosity and solids pressure, which takes into account the particle-particle collisions.     

Facile synthesis of binary metal substituted copper oxide as a solar light driven photocatalyst and antibacterial substitute

This work presents the synthesis of Cu_0.95Mn_0.05O (CMO), Cu_0.95Ag_0.05O (CAO), and Cu_0.9Mn_0.05Ag_0.05O (CMAO) samples via wet chemical route for photocatalytic and antibacterial applications. The phase, morphology, chemical composition, and absorption range of the transition metal substituted CuO samples were investigated using various techniques such as PXRD, FESEM, EDX, and UV/Visible spectroscopy . The photocatalytic and antibacterial aptitude of all the synthesized samples was tested using methylene blue (MB) and bacterial strains. The results of application studies showed that the CMAO sample has a greater potential for dye degradation and bacterial strain destruction because of its long-lived photo-generated reactive species. More precisely, among all the synthesized samples, the CMAO sample showed excellent photocatalytic activity and degraded 83.9% dye at a higher rate constant value (0.0127 min^?1). Moreover, the CMAO sample also showed better bactericidal activity against Gram-positive (S. aureus) and Gram-negative bacterial strains (E. coli). Actually, components of the bacterial cell membrane are also organic like organic dyes, so they are likely to degrade by photo-generated species. The results revealed that binary metal substituted CuO (CMAO) has an excellent ability to kill bacteria and eliminate toxic dyes from industrial effluents.     

Context-aware multimedia services modeling: an e-Health perspective

In this paper we present an e-Health framework model that can dynamically provide context-aware multimedia services to a user. The framework collects live user context by analyzing sensory data obtained from a body sensor network and multimedia content available from live heterogeneous Internet-based services. Finally, we share the implementation details and test results.     

Investigations of mixing in a fluid Jet agitated tank

Mixing can be achieved in a variety of ways including mechanical agitation, agitation by a fluid jet impingement or by static mixers. This article is concerned with mixing by a fluid jet impingement. Jet mixing can be described as a fast-moving stream of liquid being injected into a slow-moving or stationary liquid. In this study, computational fluid dynamics (CFD) is used to investigate the performance of a jet mixer. The degree of mixing has been evaluated by monitoring mixing of a hot volume of fluid in the larger tank until criteria for 95% mixing are met at a number of monitoring points. A wide range of jet injection rates has been investigated. Good agreement was shown between numerical and published experimental results. Moreover, the need to monitor mixing at more than one point, and especially at points in zones with little liquid motion, is shown to be necessary. Numerical results provided detailed plots of velocity and temperature fields and clearly showed the locations of zones with very low velocities, which require the longest time to become well mixed.     

Structures and Performance of White Clay-Filled Isotactic-Polypropylene Composites Prepared by Double-Molding Techniques

Various contents of Bangladeshi white clay (WC)-filled Isotactic polypropylene (iPP) composites were fabricated by double-molding techniques. Scanning electron micrographs shows a good impact between iPP matrix and fillers. X-diffraction and IR spectroscopic measurements reveal that inclusion of fillers develops an additional γ-crystal along with the α- and β-crystals that are merely observed in the neat iPP. Young's modulus and microhardness are found to increase with increasing WC content. Thermal analyses represent a considerable increase of thermal stability of the composites with filler addition. Appearance of new crystalline phase by filler inclusion and performances of the composites are discussed in detail.     

Multiplex PCR in Species Authentication: Probability and Prospects—A Review

Food forgery is one of the most articulated socio-economic concerns which contributed to increase people’s awareness on what they eat and how and where it is produced. Consumers are anxious about the consequences of food falsification on their choices, religious rituals, health, and hard-earned fortunes. The recent scandals of horse and rat meats in Europe and China have given us a brainstorming apprehension on the detection, differentiation, and identification of meat products. To restore consumers’ trust and protect wildlife in natural habitats, researchers and policy-making and policy-implementing authorities have massively monitored all steps in the production of foods and food materials. Analytical approaches based on lipids, proteins, and DNA have been proposed for the authentication of meat species under pure and complex matrices. However, protein and lipid-based methods are less effective since the target biomarkers could be modified throughout the processing treatments. On the other hand, DNA-based species identification schemes have gained wider acceptance and reliability because of the superior stability and universality of DNA in all tissues and cells. We systematically presented here major species detection schemes with special emphasis on multiplex polymerase chain reaction (PCR) of both end-point and real-time platforms. We believe this short but comprehensive review would serve as a reference guide for the developers and users of multiplex PCR and others DNA-based techniques.     

Detailed macro and micromorphology of grasses caryopsis using scanning electron and light microscopy

Micromorphology of 15 grass caryopsis was investigated through scanning electron microscopy for its implications in the identification of grasses. Both macro and micromorphological characters especially caryopsis shape and surface morphology were found significant in the taxonomic diagnosis. Shape morphology of caryopsis varied among the species and lanceolate, fusiform, narrow ellipsoidal, ovate, elliptical, plano-convex, fusiform, linear ovate, broadly elliptical, broadly pllipsoidal, plano-convex, oblique ovate, and subglobose shapes were recorded. Digitaria nodosa (3.31 × 0.7 mm) and Echinochloa crus-galli (3.26 × 1.44 mm) had the largest caryopsis size, while Acrachne racemosa (0.76 × 0.54 mm) and Eragrostis minor (0.62 × 0.38 mm) had the smallest caryopsis size. Macro and micromorphological characters were useful for the diagnosis of genus and species. Utilizing both qualitative and quantitative character taxonomic key at generic and species level were made.     

SAM-modified microdisc electrode arrays (MDEAs) with functionalized carbon nanotubes

The construction of a novel voltammetric transducer employing mixed acid-chopped, oxidatively modified, single-walled carbon nanotubes (HOOC-SWNT-COOH) covalently coupled to alkane thiol self-assembled monolayers (SAMs) that were deposited onto gold microdisc electrode arrays (MDEA-Au) (1296 microdiscs, 100 μm diameter each) has been demonstrated. The chemisorption of cysteamine (CA) and 11-amino-1-undecanethiol (11-AUT) SAMs onto the MDEAs resulted in MDEA-Au|CA and MDEA-Au|11-AUT, which when conjugated with the HOOC-SWNT-COOH produced MDEA-Au|CA|SWNT and MDEA-Au|11-AUT|SWNT electrodes. Electrodes were characterized by multiple scan rate cyclic voltammetry in the presence of ferrocene monocarboxylic acid and by AFM and compared. As expected, CA modification of MDEA-Au produced a disordered film that did not alter the effective surface area of the MDEA while 11-AUT modification resulted in passivation and a 50% reduction in effective surface area. The conjugation of the SWNT to the CA-modified and the 11-AUT-modified MDEA-Au surface returned well-resolved voltammograms with highest peak currents (I_pa = 5.54 × 10⁻⁴ A, I_pc = 2.34 × 10⁻⁴ A at 100 mV/s). The effective area of MDEA-Au|CA|SWNT was increased by 200% while that of MDEA-Au|11-AUT|SWNT was increased by 100%. AFM showed SWNTs to be vertically oriented on the CA-modified surface but to be horizontally arranged and bundled on the 11-AUT surface.     

Fabrication of binary metal substituted CdO with superior aptitude for dye degradation and antibacterial activity

With the widespread increase in the emergence of antibiotic-resistant bacterial strains and extent of the water contamination by organic pollutants, a considerable effort is required for the development of effective and safe materials to treat infections and remove water pollutants. Herein, we have developed doped and co-doped cadmium oxide CdM₁M₂O (M₁ = Mn, M₂ = Al, Sr, Ba) nanostructures with antibacterial activity against three bacterial strains (Staphylococcus aureus, Klebsiella pneumoniae, and Proteus vulgaris) and photocatalytic activity against methylene blue dye under direct sunlight irradiation. A very inexpensive and simple wet chemical approach was employed to fabricate the doped and co-doped nanostructures. The results of the antibacterial tests on Klebsiella pneumoniae, Staphylococcus aureus, and Proteus vulgaris bacteria indicated that all the prepared nanostructures possessed superb antibacterial properties. The Cd_1-(x+y) Mn_xAl_yO nanostructures exhibited excellent degradation efficiency with typical organic dye (methylene blue) within 1 h of direct sunlight irradiation. The efficient synergistic antibacterial and photocatalytic activities coupled with their recyclability demonstrated the potential of Cd_1-(x+y) Mn_xAl_yO nanostructures for practical use in polluted water remediation and environmental protection applications. The simple method used for synthesizing the nanostructures to enhance their antibacterial and photocatalytic activities can potentially be extended to fabricate other photocatalysts and antibacterial agents.     

Mono and co-substitution of Sr2+ and Ca2+ on the structural,electrical and optical properties of barium titanate ceramics

In this work, Ba_0.9Sr_0.1TiO₃, Ba_0.7Sr_0.3TiO₃, Ba_0.5Sr_0.5TiO₃, Ba_0.5Ca_0.25Sr_0.25TiO₃ and Ba_0.5Ca_0.5TiO₃ have been synthesized to evaluate the influence of mono and co-substitution of A-site dopants (Sr²⁺ and Ca²⁺) on the structural, electrical and optical properties of BaTiO₃ ceramics. Sr²⁺ added samples showed a tetragonal structure which became slightly distorted with increasing Sr²⁺ concentration and finally achieved a cubic structure for x?=?0.50. Ba_0.5Ca_0.5TiO₃ also retained their tetragonality with limited solubility. Presence of second phase, CaTiO₃ demonstrated the fact of restricted solubility. The concurrent effect of Sr²⁺ and Ca²⁺ didn't alter the tetragonal structure. Sr²⁺ substitution enhanced the apparent density as well as grain size which stimulated the domain wall motion and improved dielectric properties. However, the ferroelectric nature of Ba_1-xSr_xTiO₃ was poor due to the redistribution of point defect at grain boundary. The optical band gap was found to be reduced from 3.48?eV to 3.28?eV with increasing Sr²⁺ content. Co-substitution of cations improved the electrical property significantly. The highest value of dielectric constant was found to be ～547 for Ba_0.5Ca_0.25Sr_0.25TiO₃ ceramics. Both Ba_0.5Ca_0.25Sr_0.25TiO₃ and Ba_0.5Ca_0.5TiO₃ had developed P-E loop having lower coercive field and moderate optical band gap energy. Co-doping with Sr²⁺ and Ca²⁺ was a good approach enhancing materials electrical as well as optical property.