Silk fibroin protein from mulberry and non-mulberry silkworms: cytotoxicity, biocompatibility and kinetics of L929 murine fibroblast adhesion

Silks fibers and films fabricated from fibroin protein of domesticated mulberry silkworm cocoon have been traditionally utilized as sutures in surgery and recently as biomaterial films respectively. Here, we explore the possibility of application of silk fibroin protein from non-mulberry silkworm cocoon as a potential biomaterial aid. In terms of direct inflammatory potential, fibroin proteins from Antheraea mylitta and Bombyx mori are immunologically inert and invoke minimal immune response. Stimulation of murine peritoneal macrophages and RAW 264.7 murine macrophages by these fibroin proteins both in solution and in the form of films assayed in terms of nitric oxide and TNFalpha production showed comparable stimulation as in collagen. Kinetics of adhesion of L929 murine fibroblasts, for biocompatibility evaluation, monitored every 4 h from seeding and studied over a period of 24 h, reveal A. mylitta fibroin film to be a better substrate in terms of rapid and easier cellularization. Cell viability studies by MTT assay and flow cytometric analyses indicate the ability of fibroin matrices to support cell growth and proliferation comparable to collagen for long-term culture. This matrix may have potential to serve in those injuries where rapid cellularization is essential.     

Influence of Symmetric Underlap on Analog,RF and Power Applications for DG AlGaN/GaN MOS-HEMT

Silicon - An Underlap Double Gate (U-DG) Symmetric Heterojunction AlGaN/GaN Metal Oxide Semiconductor High Electron Mobility Transistor (MOS-HEMT) with varying source and drain underlap lengths...     

The Influence of Collector Fluid Inlet Temperature on the Performance of a Solar-Assisted Absorption System Using Step-Finned Flat-Plate Collector

In the present work, an extensive analysis is developed for an evaluation of the thermal performance of a solar-powered H₂O/LiBr absorption cooling system using a step-fin flat-plate collector (SFC). The performance parameters, namely, collector efficiency factor, heat removal factor, and collector efficiency, for the SFC is derived. A system simulation model has been developed to analyze the system performance—that is, to identify an operating criterion as a function of the collector fluid inlet temperature (T _FI). It has been observed from the results that the performance of the system depends strongly on T _FI. Simulation results show that the system operates optimally (maximum coefficient of performance) at an optimal T _FI. When the system runs at this optimal value of T _FI, minimum collector material is required. Thus, when using SFC in place of a rectangular-fin flat-collector, thirty-five percent or more collector material can be saved. However, it has been observed that the effect of thermal conductivity on the plate volume of SFC has a marginal effect.     

An overview of unsolved deficiencies of direct methanol fuel cell technology: factors and parameters affecting its widespread use

Direct methanol fuel cells (DMFCs) have evolved over the years as a potential candidate for application as a power source in portable electronic devices and in transportation sectors. They have certain associated advantages, including high energy and power densities, ease of fuel storage and handling, ability to be fabricated with small size, minimum emission of pollutants, low cost, ready availability of fuel and solubility of fuel in aqueous electrolytes. However, in spite of several years of active research involved in the development of DMFC technology, their chemical‐to‐electrical energy conversion efficiencies are still lower compared with other alternative power sources traditionally used. This review paper will focus on the existing issues associated with DMFC technology and will also suggest on the possible developmental necessities required for this technology to realize its practical potentials. Copyright © 2014 John Wiley & Sons, Ltd.     

Electromagnetic THz Radiation Modeling by DPSM

THz or T-ray imaging and spectroscopy are becoming increasingly popular nondestructive evaluation techniques for damage detection and characterization of materials. In order to understand the interaction between the T-ray electromagnetic waves and dielectric media a reliable model of electromagnetic wave propagation through dielectric materials must be developed. A recently developed semi-analytical method called the distributed point source method (DPSM) is extended to model electromagnetic wave propagation in THz range. Since T-ray signals generated by emitters or sources are close to Gaussian beams, the DPSM modeling is carried out for Gaussian beams generated by finite sized emitters. The DPSM generated results are compared with the analytical and experimental results. T-ray propagation in layered structures in absence of any anomaly and the interaction between the Gaussian beam and the spherical scatterer are also investigated.     

Approximate Techniques for the Performance Analysis and Optimization of Two-Dimensional Plate Fins Circumscribing Circular Tubes Plate

Efficiency of noncircular fins circumscribing circular tubes is generally determined by one of two approximate techniques, the equivalent annulus method or the sector method. In the present work the predictions of these two methods are compared with results obtained from a semianalytical technique for square, hexagonal, and eccentric annular fins. It is observed that the accuracy of the equivalent annulus method reduces with the increase of the two-dimensionality of the fins. However, the sector method guarantees very close agreement with the semianalytical technique over a wide range of parametric variations for all the fins. An improved definition of fin efficiency for the sector method is also put forward to take care of the heat loss from fin tips. Finally, it is shown that the optimum dimensions of the fins determined by the sector method closely match the predictions of the semianalytical technique.     

THERMODYNAMICS OF ALKANOLAMINE + WATER SYSTEM

Design of gas treating processes requires knowledge of the vapor-liquid equilibrium behavior of the (acid gas + aqueous alkanolamine) system. The present study is focused on thermodynamics and associated nonideal behavior of binary MEA + H₂O, DEA + H₂O, and MDEA + H₂O systems, which is required to predict the vapor-liquid equilibrium of acid gases such as CO₂ and H₂S over aqueous alkanolamine solutions. Determination of binary interaction parameters and analytical prediction of infinite dilution activity coefficient, heats of solution at infinite dilution, the excess Gibbs free energy, and excess enthalpy for nonideal alkanolamine-water systems are the objectives of this study.     

Numerical simulation and optimisation of unconventional three‐section simulated countercurrent moving bed chromatographic reactor for oxidative coupling of methane reaction

The simulated countercurrent moving‐bed chromatographic reactor (SCMCR) has been reported to significantly enhance methane conversion and C₂ product yield for oxidative coupling of methane (OCM) reaction, which is otherwise a low per pass conversion reaction. A mathematical model of an unconventional three‐section SCMCR for OCM was first developed and solved using numerically tuned kinetic and adsorption parameters. The model predictions showed good agreement with available experimental results of SCMCR for OCM. Effects of several process parameters on the performance of SCMCR were investigated. A multi‐objective optimisation problem was solved at the operating stage using state‐of‐the‐art AI‐based non‐dominated sorting genetic algorithm with jumping genes adaptations (NSGA‐II‐JG), which resulted in Pareto Optimal solutions. It was found that the performance of the SCMCR could be significantly improved under optimal operating conditions. © 2011 Canadian Society for Chemical Engineering