Luminescence properties of Mn and Ni doped ZnS nanoparticles synthesized by capping agent

ZnS and transition metal (Mn and Ni) doped ZnS were synthesized by a simple chemical method using alkyl hydroxyl ethyl dimethyl ammonium chloride (HY) as capping agent. The structural and optical properties were studied using various techniques. FTIR and X-ray diffraction (XRD) can be used to identify the chemical bonding and crystal structure. The XRD analysis show that the particles are in cubic structure. The mean size of the nanoparticles calculated through Scherrer equation is in the range of 5–2.5 nm. Elemental dispersive analysis of doped samples reveals the presence of doping ions. The transmission electron microscopic studies show that the synthesized particles are in spherical shape. Optical characterization of both undoped and doped samples was carried out by ultraviolet–visible and photoluminescence spectroscopy. The absorption spectra of all the samples are blue shifted from the bulk ZnS.     

MPLS technology in wireless networks

Recently, there has been increasing demand for Multi-protocol label switching (MPLS) technology in most internet service provider networks. The application of MPLS technology in wireless networking is evolving. Therefore, next generation wireless networks are required to have IP mobility solutions with high reliability, low-latency handoffs, and trustworthy security. In this paper, we propose a novel multi-path mobility scheme for fast handoff to achieve these requirements. The scheme is based on MPLS multi-path forwarding and network coding based on modulo-p Galois finite field GF(p = 2 ⁿ ) arithmetic. The simulation results show that our proposed approach scales well to fulfill fast handoff/handover performance while providing security for transmitted data with minor bandwidth overhead.     

Respiration rate,ethylene production and biochemical changes during fruit development and maturation of jujube (Ziziphus mauritiana Lamk)

Jujube fruits (Ziziphus mauritiana Lamk) of cv Zaytoni were harvested from fruit set until maturity to study some physiological and biochemical changes. Jujube fruit cv Zaytoni displayed a double‐sigmoid growth curve with a very short second stage (2 weeks). Changes in respiration rate and ethylene production during fruit development were typical of climacteric fruits, the peak of ethylene production coinciding with the climacteric rise in respiration. As for chemical constituents, reducing sugars were dominant and sucrose was absent in ripe fruit. Total soluble solid content was low during the early stages of growth, then increased to a peak in ripe fruit. Titratable acidity was low initially, but increased to a peak in physiologically mature fruit and declined rapidly in ripe fruit. The pattern of changes in protein content was typical of that characterising climacteric fruits. © 2002 Society of Chemical Industry     

Performance, emissions and heat release characteristics of direct injection diesel engine operating on diesel oil emulsion

Emulsions of diesel and water are often promoted as being able to overcome the difficulty of simultaneously reducing emissions of both oxidises of nitrogen (NO_x) and particulate matter from diesel engines. In this paper we present measurements of the performance and NO_x and hydrocarbon emissions of a diesel engine operating on a typical diesel oil emulsion and examine through the use of heat release analysis differences found during its combustion relative to standard diesel in the same engine. While producing similar or greater thermal efficiency and improved NO_x and hydrocarbon emission outcomes, use of the emulsion also results in an increase in brake specific fuel consumption. Use of the emulsion is also shown to result in a retarded fuel injection, but smaller ignition delay for the same engine timing. As a result of these changes, cylinder pressures and temperatures are lower.     

Lattice Boltzmann simulation of natural convection and heat transfer from multiple heated blocks

This study is aimed to investigate the natural convection heat transfer from discrete heat sources (similar to heated microchips) using Bhatnagar‐Gross‐Krook lattice Boltzmann method via graphics process unit computing. The simulation is carried out separately for three and six heated blocks model for different Rayleigh numbers and fixed Prandtl number, $Pr=0.71$ (air). The uniformly heated blocks are placed at the bottom wall inside a rectangular enclosure. The enclosure is maintained by the cold temperature at its left and right walls. The top and bottom surface is maintained by adiabatic conditions apart from the regions where blocks are attached to the bottom wall. The numerical code is validated with the benchmark heat transfer problem of side‐heated square cavity as well as with an experimental study for one discrete heat source. The rate of heat transfer is presented in terms of the local Nusselt and average Nusselt number for each block. It is found that the heat transfer rate becomes maximized in the leftmost and rightmost blocks due to the adjacent cold walls. It is found that the number of blocks and their positions play a substantial role in determining their collective performance on the heat transfer rate.     

Two-dimensional numerical modeling of combustion of Jordanian oil shale

A two-dimensional (2-D) modeling of the burning process of Jordanian oil shale in a circulating fluidized bed (CFB) burner was done in this study. The governing equations of continuity, momentum, energy, mass diffusion, and chemical combustion reactions kinetics were solved numerically using the finite volume method. The numerical solution was carried out using a high-resolution 2-D mesh to account for the solid and gaseous phases, k-ε turbulence, non-premixed combustion, and reacting CFD model with the same dimensions and materials of the experimental combustion burner used in this work. The temperature distribution and evolution of species were also computed.

Proximate and ultimate analyses were also performed to evaluate the air–fuel ratio and ash content. The required thermophysical properties, such as heating value, density, and porosity were obtained experimentally, while the activation energy was obtained from published literature.

It was found that the temperature contours of the combustion process showed that the adiabatic flame temperature was 1080 K in a vertical burner, while the obtained experimental results of maximum temperature at various locations of the burner in actual, non-adiabatic, non-stoichiometric combustion reached 950 K, showing good agreement with the model.     

Review of molecular imprinting polymer: basic characteristics and removal of phenolic contaminants based on the functionalized cyclodextrin monomer

Cyclodextrins (CDs) are formed of starch molecules that are linked together in a cyclic ring. They are composed of five or more (1, 4) connected D-glucopyranoside units. CDs have toroidal, hollow truncated cone structures with exterior hydrophilic edges and internal hydrophobic cavities. The numerous hydroxyl groups available in cyclodextrins are active sites capable of forming various sorts of connections. They can be cross-linked or derived to generate monomers able to form branching or linear networks. Furthermore, they can form inclusion complexes with a variety of guest molecules, including organic and inorganic molecules, thus changing their physicochemical properties, The modification of the imprinting method could produce molecularly imprinted polymers that are stable, dependable, long-lasting, selective, and cost-effective. As a result, molecularly imprinted polymers are becoming increasingly popular in chemical separation and analysis. As found in previous studies, the monomers of cyclodextrins used in molecular imprinting have a higher binding impact on target molecules. The purpose of this study is to highlight the application of imprinting technology utilizing cyclodextrins as a valuable functional monomer in the remediation of phenolic compounds by examining and assessing relevant works published in the literature. © 2022 Society of Chemical Industry (SCI).     

Modelling and Simulation of Design Variants for the Development of 4H-SiC Thyristors

Silicon - Wide band-gap semiconductor materials such as SiC have created a contemporaneous worldwide interest in high power electronic applications and boosted the research possibilities....     

Kinetic study of Hg(II)-promoted substitution of cyanide from hexacyanoferrate(II) in an anionic surfactant medium by 2,2′-bipyridine

The kinetic investigation of Hg(II)-promoted reaction between [Fe(CN)₆]⁴⁻ and 2,2′-bipyridine (Bipy) has been performed in anionic sodium dodecyl sulfate (SDS) micellar medium by recording the surge in absorbance at 400 nm, corresponding to ultimate reaction product [Fe(CN)₄ Bipy]²⁻ using UV–visible spectrophotometer. Pseudo-first-order condition has been used to examine the progress of reaction as a function of temperature, [Fe(CN)₆⁴⁻], ionic strength, [SDS], pH, [Hg²⁺], and [Bipy] by changing one parameter at a time. The results exhibit that [Hg²⁺], [SDS], and pH are the decisive parameter showing maximum reaction rate at 1.5 × 10⁻⁴ mol dm⁻³, 6.0 × 10⁻³ mol dm⁻³, and 3.8, respectively. [Fe(CN)₆]⁴⁻ does not show any appreciable effect on the critical micellar concentration (CMC) of SDS as the polar head of SDS and [Fe(CN)₆]⁴⁻ both are negatively charged. Variable order kinetics was observed for [Fe(CN)₆]⁴⁻ and Bipy in their examined concentration range. The reverse response observed in the reaction rate with [KNO₃] shows a negative salt effect. The K⁺ provided by K₄[Fe(CN)₆] and KNO₃ decreases the repulsion between the negatively charged heads of the surfactant molecules thereby decreasing the CMC of SDS. The negative value for the entropy of activation also supports the interchange dissociative (I_d) mechanism recommended by us.