Synthesis and Analysis of Triphenylamine: A Review

In this paper, synthesis and characteristic of arylamine‐type molecules, particularly triphenylamine are discussed. An overview of the physical properties and chemical characteristics of these types of molecules is provided. Different synthesis methods and mechanisms involved for the production of these molecules and their analysis by HPLC are presented. Finally, a brief note about their purification is presented.     

Learning Automata Based Face-Aware Mobicast

Target tracking is one of the most popular applications of the wireless sensor networks. It can be accomplished using different approaches and algorithms, one of which is the spatiotemporal multicast protocol, called “mobicast”. In this protocol, it is assumed that the area around the moving target, called the delivery zone, is known at any given time during the operation of the network. The aim of the protocol is to awake sensor nodes, which will be within the delivery zone in the near future, to be prepared for tracking the approaching moving target. In this paper, we propose a novel mobicast algorithm, aiming at reducing the number of awakened sensor nodes. To this end, we equipped every sensor node with a learning automaton, which helps the node in determining the sensor nodes it must awaken. To evaluate the performance of the proposed algorithm, several experiments have been conducted. The results have shown that the proposed algorithm can significantly outperform other existing algorithms such as forward-zone constrained and FAR in terms of energy consumption, number of active nodes, number of exchanged packets and slack time.     

Analysis of Acceleration Effect in Data Dissemination in Vehicular Networks Using Rateless Codes

Mobility models of nodes have an important role in the evaluation of data dissemination protocols in vehicular ad hoc networks (VANETs). Many recent researches have used the constant velocity mobility models while vehicles have acceleration and their speeds change as they move. Because of the dynamic nature of VANETs, the network changes from a densely connected to the sparsely connected environment in a short time. In sparsely connected networks, it is said that vehicles move in clusters. In this paper, the constant acceleration mobility calculations for the sparsely connected network and its characteristics have been presented. These characteristics are usable for the evaluation of the data dissemination protocols in VANETs. The results show that acceleration affects the number of viewed clusters during the trip and the number of vehicles within a cluster. In fact, acceleration has a significant impact on the network sparsely connection. This matter shows that the appropriate data dissemination protocol should be used to study the acceleration effect which is applicable in sparse networks. The analysis in this research provides the necessary background for better understanding and accurate calculations for the evaluation of data dissemination in VANETs.     

A comparative study using direct hydrothermal and indirect fusion methods to produce zeolites from coal fly ash utilizing single-mode microwave energy

This paper investigates the effects of microwave irradiation on the synthesis of zeolite Na-A from coal fly ash at atmospheric pressure. Microwave irradiation has shown to accelerate zeolitization from several hours to several minutes. A single-mode laboratory-scale microwave was employed, which enabled control of irradiated power and temperature of the reaction mixture, while the pressure was controlled by affixing a condenser on the 40 mL Teflon reactor vessel with a working volume 20 mL. Design of Experiment was used to compare two methods of converting CFA to zeolite-A, direct hydrothermal method and indirect fusion method. Experiments conducted were two level four factorial designs. The first factor considered was the categorical factor of conversion method (hydrothermal vs fusion), while the other three factors investigated were power (P), time (θ), and aluminate concentration (δ). Zeolite produced from CFA (CFAZA) was characterized using XRD, FTIR, SEM, TGA, BET, and cation exchange capacity. It was observed that the crystallinity of the product was influenced by factors such as, conversion method, power, time, and aluminate concentration. The hydrothermal and fusion products were comparable to each other in their characteristics, however, hydrothermal CFAZA performed better at immobilizing heavy metal ions and showed better crystalline structure, whereas fusion CFAZA had a higher BET surface area and a slightly higher CEC. Regardless of the performance of the categorical factors the other factors, i.e., power, time, and aluminate concentration followed the same trend for both types of CFAZA.     

Quantitative determination of physical and chemical measurands in honey by near-infrared spectrometry

Fourier transform near-infrared spectroscopy (FT-NIR) was evaluated to quantitatively determine 24 different measurands in honey. The reference values of 421 honey samples of different botanical origins were determined by classical physical and chemical methods. Partial least squares regression was used to develop the calibration models for the measurands studied. These calibrations were then validated using independent samples and proved satisfying accuracies for the determination of water (standard error of prediction: 0.3 g/100 g), glucose (1.3 g/100 g), fructose (1.6 g/100 g), sucrose (0.4 g/100 g), total monosaccharide content (2.6 g/100 g) as well as fructose/glucose ratio (0.09) and glucose/water ratio (0.12). The prediction accuracy for hydroxymethylfurfural, proline, pH-value, electrical conductivity, free acidity and the minor sugars maltose, turanose, nigerose, erlose, trehalose, isomaltose, kojibiose, melezitose, raffinose, gentiobiose, melibiose, maltotriose was poor and unreliable. The results demonstrate that near-infrared spectrometry is a valuable, rapid and non-destructive tool for the quantitative analysis of some measurands related to the main components in honey.     

How many subjects to screen? A practical procedure for estimating multivariate normal probabilities for correlated variables.

Suggests a practical procedure for estimating the number of Ss that need to be screened to obtain a sample of fixed size that meets multiple correlated criteria. The procedure is based on the fact that least squares regression provides a good quadratic fit for Monte Carlo estimates of multivariate probabilities when they are plotted as a function of mean pairwise correlations (r) for the criterion variables. The equations given here can be used to predict selected 3- to 5-variable joint probabilities with reasonable accuracy as long as pairwise correlations for the selection criteria range from .10 to .90. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of the corrosion products formed on copper in sulfur containing environments

Tarnishing layers grown on copper exposed to air contaminated by traces of sulfur dioxide and/or hydrogen sulfide were detected by a coulometric and characterized by a chemical method. Depending on the nature of the corrosive gas, or on the use of a gas mixture, it was found that sulfate, sulfide, oxides or a mixed oxide-sulfide compound could be formed in these conditions. The same tarnishing products were found, either in hydrogen sulfide or in a sulfur dioxide + hydrogen sulfide mixture, and the same linear growth law of the copper (I) sulfide was also found, within the limits of the duration of the corrosion test, in the two gaseous environments.     

A novel silicon nanotips antireflection surface for the micro Sun sensor

We have developed a new technique to fabricate an antireflection surface using silicon nanotips for use on a micro Sun sensor for Mars rovers. We have achieved randomly distributed nanotips of radii spanning from 20 to 100 nm and aspect ratio of approximately 200 using a two-step dry etching process. The 30 degrees specular reflectance at the target wavelength of 1 microm is only about 0.09%, nearly 3 orders of magnitude lower than that of bare silicon, and the hemispherical reflectance is approximately 8%. When the density and aspect ratio of these nanotips are changed, a change in reflectance is demonstrated. When surfaces are covered with these nanotips, the critical problem of ghost images that are caused by multiple internal reflections in a micro Sun sensor was solved.     

Cr2O3 nanoparticles: A promising candidate to improve the mechanical properties and corrosion resistance of Ni-Co alloy coatings

This study was aimed to assess the effects of reinforcement nanoparticles content, on the microstructural features, mechanical properties, and corrosion-related properties of Ni-Co-Cr₂O₃ nanocomposite coatings. Scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), and X-ray diffraction (XRD) analysis were employed in order to evaluate the microstructural features and chemical composition of the nanocomposites. Moreover, the microhardness tester and electrochemical impedance spectra (EIS) tests coupled with potentiodynamic polarization measurements were used to investigate the mechanical and corrosion-related properties, respectively. Results demonstrate that albeit the volume fraction of cobalt in coating, average particle size, Cr₂O₃ nanoparticle content in coating, and microstructural features are of prime significance in determining the mentioned properties of the nanocomposite coatings, Co content is more important. Actually, Cr₂O₃ nanoparticles serve as suitable nucleation sites for Co particles deposition throughout the microstructure. Thus, combined actions of Cr₂O₃ nanoparticles incorporation and their optimal content ensures the nucleation of high population of Co particles, which significantly contributes to the improvement in the properties. The Ni-Co-8.9 wt%Cr₂O₃ nanocomposite coating exhibits the superior mechanical and corrosion-related properties.