ESTIMATION OF VAPOR PRESSURES OF ORGANIC NITROGEN AND SULFUR COMPOUNDS BY A GROUP-CONTRIBUTION METHOD

The group-contribution method for vapor pressures of hydrocarbons and organic compounds containing nitrogen or sulfur, based on the kinetic theory of fluids, is revised and extended to include new groups containing nitrogen or sulfur. Good representation is obtained for vapor pressure data in the region 1.30-270 kPa. The method may be used to estimate vapor pressures and enthalpies of vaporization for those organic fluids containing nitrogen or sulfur, where no experimental data are available.     

Edge detection in a hexagonal-image processing framework

With processing power of computers and capabilities of graphics devices increasing rapidly, the time is ripe to reconsider using hexagonal sampling for computer vision in earnest. This paper reports on an investigation of edge detection in the context of hexagonally sampled images. It presents a complete framework for processing hexagonally sampled images which addresses four key aspects: conversion of square to hexagonally sampled images, storage, processing, and display of these images. Results from using edge detection on this framework show that (a) the computational requirement for processing a hexagonally sampled image is less than that for square sampled images, and (b) a better qualitative performance which is due to the compact and circular nature of the hexagonal lattice. This last point needs to be exploited in the development of edge detectors for hexagonally sampled images.     

On the Evaluation of the Elastic Modulus of Soft Materials Using Beams with Unknown Initial Curvature

A non‐linear optimization procedure is established to determine the elastic modulus of slender, soft materials using beams with unknown initial curvature in the presence of large rotations. Specifically, the deflection of clamped‐free beams under self‐weight – measured at different orientations with respect to gravity – is used to determine the modulus of elasticity and the intrinsic curvature in the unloaded state. The approach is validated with experiments on a number of different materials – steel, polyetherimide, rubber and pig skin. Because the loading is limited to self‐weight, the strain levels attained in these tests are small enough to assume a linear elastic material behaviour. This non‐destructive methodology is also applicable to engineered tissues and extremely delicate materials in order to obtain a quick estimate of the material's elastic modulus.     

Harnessing power from sea water using nano material as photocatalyst and solar energy as light source: the role of hydrocarbon as dual agent

The splitting of water in the presence of ordinary and nano TiO₂ was carried out using hydrocarbon as a dual agent and solar energy as a light source for these experiments. The hydrogen gas evolved was tested and measured using downward displacement of water. The observed results show that more hydrogen was evolved when nano TiO₂ was used as catalyst due to the larger surface area of the nano material. The splitting of sea water yields more hydrogen compared with ordinary water due to the presence of electron donating sodium ions in water. The added hydrocarbon plays a dual role as electron donor and as a trapping agent, which enhances the production of hydrogen to a greater extent compared with the regular donors such as olefin. Copyright © 2013 John Wiley & Sons, Ltd.     

A Generalized Relationship for Determination of Tensile Strength of Fine-Grained Soils from Shrinkage Characteristics

Tensile strength of fine-grained soils has been extensively investigated by earlier researchers and several methodologies have been evolved for its determination. However, either most of these methods are not valid/applicable for a wide range of moisture contents or they involve tedious sample/specimen preparation. In this context, the methodology of determining tensile strength by employing thin films, which is available in the literature, has been found to be quite handy and useful. It has been observed that a unique relationship exists among the tensile strength, moisture content, and shrinkage characteristics of fine-grained soils. This methodology is appreciable due to its applicability to a wide range of moisture contents, comparable ease of sample preparation and testing, and the obtained results lack generalization. Exhaustive tests were conducted on fine-grained soils of entirely different characteristics and generalized relationships have been proposed between the percentage linear shrinkage, tensile strength, and moisture content (defined as liquid to solid ratio). Based on a critical analysis of the results available in the literature, the efficiency of such relationships for determination of tensile strength of fine-grained soils has been demonstrated. In the authors’ opinion, such relationships would be quite useful for determining tensile strength of fine-grained soils from their linear shrinkage, which can easily be measured in a conventional geotechnical engineering laboratory.     

Bio-inspired Optimization Routing Technique Using DNA Sequencing Algorithm for Wireless Sensor Networks

Wireless Personal Communications - Routing optimization is a promising platform in wireless sensor network (WSN) for many researchers to work on various problems related to the balancing of...     

Ceramic Powder Synthesis by Spray Pyrolysis

A variety of spray pyrolysis (SP) techniques have been developed to directly produce ceramic powders from solutions. This paper reviews the current status of these processes in terms of the process parameters that enable the formation of particles with controlled morphology and composition. A model incorporating solute diffusion in the droplet and solvent evaporation from the droplet surface is presented to establish the critical parameters leading to solid particle formation. The model illustrates that solid particles can be obtained if solutes with high solubility and a large difference between the critical supersaturation and equilibrium concentration are used and if the process is designed to avoid solvent boiling. It is demonstrated that mixed metal oxide, non-oxide, and composite particles that are solid, hollow, porous, or fibrous can be produced by modifying the precursor characteristics, solution properties, and process parameters. The physical and chemical flexibility of SP processes offers numerous opportunities for the controlled synthesis of advanced ceramic powders and films. However, production rates are limited by the need to produce < 5-μm-diameter droplets and to avoid subsequent droplet coagulation. Developments in process controls, atomization, and system design are required for wider commercialization of SP-type processes.     

Organic thin film transistors: Materials,processes and devices

For the past ten years, organic materials have been extensively investigated as an electronic material for thin film transistor (TFT) devices. Organic materials offer strong promise in terms of properties, processing and cost effectiveness and they can be used in flat panel displays, imagers, smart cards, inventory tags and large area electronic applications. In this review, we summarize the current status of the organic thin film transistors including substrate materials, electrodes, semiconducting and dielectric layers; organic thin film preparation methods; morphological studies for organic thin films; electrical characterization of gate dielectric layers and semiconducting active layers; and characterization of the OTFTs. Future prospects and investigations required to improve the OTFT performance are also given. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

Nanoporous poly(methyl methacrylate)-quantum dots nanocomposite fibers toward biomedical applications

In this work, poly(methyl methacrylate) (PMMA)-CdSe/ZnS quantum dots (QDs) nanocomposite fibers were fabricated via a simple electrospinning method. The parameters including concentration of PMMA, feed rate, applied voltage and working distance between the needle tip and the fiber collecting electrode were investigated and optimized to acquire large quantity, uniform and defect-free PMMA and its QD nanocomposite fibers. The surface morphology of the fibers was characterized by scanning electron microscopy (SEM), while the fluorescence emission characteristics of the polymer nanocomposite (PNC) fibers were analyzed with fluorescence microscopy. The thermal properties of the PMMA-QDs PNC fibers were explored by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). In comparison to the pristine PMMA fibers, the PNC fibers with only 0.1 wt% QD loading showed an improved thermal stability by 15 °C for the midpoint and onset degradation temperature. Surface chemical structure and functionalities were probed by a combination of attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). New vibration bands were observed in the PNC fibers in the ATR-FTIR spectra, while the binding energy for both high resolution C 1s and O 1s spectra in the PNC fibers showed an apparent shift toward lower field. Rheological studies revealed a pseudoplastic behavior of both pristine PMMA and PMMA-QDs solutions. Moreover, the formed nanoporous PMMA-QDs fiber media exhibited an excellent biocompatibility as evidenced by the model Chinese hamster ovary (CHO) cell culturing test. The CHO cells demonstrated good adhesion, growth and viability in the reported testing.