Mechanisms of DC conduction in smart PMN–PT/paint nanocomposite films

Understanding conduction mechanisms in dielectric films are critical to their successful applications in devices. DC conduction mechanisms in lead magnesium niobate–lead titanate (0.67Pb (Mg_1/3Nb_2/3)O₃–0.33PbTiO₃)/Paint nanocomposite (PMN–PT/Paint) films are presented and discussed. The conventional cost-effective paint brushing technique was utilized to fabricate PMN–PT/paint nanocomposite films on copper substrate. Atomic force microscopy (AFM) has been recognized as one of the most powerful techniques for the analysis of surface morphologies because it creates 3D images at angstrom and nano scale. It has been exhaustively utilized in the analysis of dispersion of nano-metric components in nanocomposites and polymer blends. Thus, AFM analysis is applied in the present work for the surface morphological and dispersion of nanoparticles investigations in paint-based nanocomposites at different loading of PMN–PT nanoparticles. It is found that the PMN–PT nanoparticles are dispersed uniformly inside the paint matrix. The spatial distribution of PMN–PT in PMN–PT/Paint films is denser with higher PMN–PT content sample. A metal–insulator–metal capacitor was fabricated and the leakage current across was measured with varying voltage and temperature. The governing conduction mechanisms were examined and depicted. The activation energy of nanocomposite films fabricated with 2.5 and 8.98 wt% PMN–PT nanoparticles in the paint mixture are found to be 1.08 and 1.24 eV, respectively. The DC activation energy for former was found to be slightly lower then later and follow the Arrhenius relationship. Thus, showing the conduction was electronic and thermally activated.     

Variational image segmentation using boundary functions

A general variational framework for image approximation and segmentation is introduced. By using a continuous "line-process" to represent edge boundaries, it is possible to formulate a variational theory of image segmentation and approximation in which the boundary function has a simple explicit form in terms of the approximation function. At the same time, this variational framework is general enough to include the most commonly used objective functions. Application is made to Mumford-Shah type functionals as well as those considered by Geman and others. Employing arbitrary L(p) norms to measure smoothness and approximation allows the user to alternate between a least squares approach and one based on total variation, depending on the needs of a particular image. Since the optimal boundary function that minimizes the associated objective functional for a given approximation function can be found explicitly, the objective functional can be expressed in a reduced form that depends only on the approximating function. From this a partial differential equation (PDE) descent method, aimed at minimizing the objective functional, is derived. The method is fast and produces excellent results as illustrated by a number of real and synthetic image problems.     

MODELLING OF FORCED PERIODIC OSCILLATIONS OF CARBON MONOXIDE OXIDATION OVER PLATINUM CATALYST

The periodic switching between two feed compositions to a gradientless reactor has been found to increase significantly the average reaction rate compared with steady stale operation. Another advantage of periodic feed switching, which has not been fully exploited in catalyst studies is in kinetic model discrimination where large variations can be forced into the predicted responses of several competitive models under consideralion. The elementary step model, with parameters determined from transient experiments, is used to simulate observed transients during forced periodic feed experiments. The model is found to fit the observed behaviour well, in contrast to Langmuir-Hinshelwood models which only prove adequate for steady state behaviour. Simulation studies coupled with experimental work help to clarify the role of adsorbed species during forced cycling.     

Reaction of dichlorocarbene with fats and oils

Dichlorocarbene was generated in the presence of lard, olive, safflower, tung and menhaden oil. When solutions of fats or oils in ethyl trichloroacetate were mixed with sodium methoxide inn-heptane at 2C, unsaturated components were transformed in high conversion to dichlorocyclopropane derivatives; fats were converted to methyl-and-ethyl esters (90%) or appeared as glycerides (10%). The proportion of dichlorocyclopropane rings was the same in the glycerides as in the ester products. The reactivity of safflower oil required metered addition of reactants at 25–55C. Properties were measured on dichlorocyclo-propanoid fatty esters freed from glycerides but containing saturated esters. Chlorine content ranged from 12–33%. Compatibility with silicone oils was substantially improved. Viscosities and densities increased with chlorine content. Viscosity indices were 135,150,49,67 and 79 for products from lard, olive, safflower, tung and menhaden oil. Dichlorocarbene could be generated without alcoholysis of glycerides by decomposition of sodium trichloroacetate. This gave dichlorocyclopropanes from safflower oil unsaturates in 50% conversion, but failed with lard. Analyses were performed by TLC, argentation and GLC. Presented at the AOCS Meeting, Minneapolis, 1963. A laboratory of the E. Utiliz. Res. & Dev. Div., ARS, USDA.     

Comparisons of the effect of electrical stimulation methods on postmortem pH decline in beef muscle

Results of four electrical stimulation (ES) studies were summarized to demonstrate the impact of different ES parameters on pH decline patterns in postmortem M. longissimus thoracis et lumborum. Postmortem pH decline was modeled as a non-linear function of time, and estimates of minimum obtainable pH, pH decline rates, and time to reach pH 6·0 were compared for each study. The decline model for study 4 (AC, 60 Hz, 50 V; 5 min post mortem) had a larger (P < 0·05) estimate for decline rate than that for study 1 (AC, 60 Hz, 400 V; 1 h post mortem) and the control (non-stimulated) data. The model estimate of time to pH 6·0 (0·56 h) for study 4 was the shortest (P < 0·05) for all treatments. Different ES parameters produce different pH decline patterns post mortem and, therefore, may impact product quality and fabrication and chilling protocols adopted in fresh beef processing.     

Recent developments in identifying and quantifying emotions during food consumption

Emotions and the consumption of food and beverages are inextricably intertwined. As the fields of sensory and consumer science seek to better conceptualize the consumer experience, interest in emotion measurement is growing. Emotions can provide key information to differentiate between products and predict consumer choice as well as give more detail about product perception. There are several emotion measurement instruments, including physiological methods and facial recognition, self‐reported verbal emotion measurement and self‐reported visual emotion measurement. This review discusses the purpose of measuring emotions, what is the definition of an emotion, what different instruments are available, and touches upon some promising research to deepen the connection between food and emotions. © 2016 Society of Chemical Industry     

Robust Multivariate Outlier Detection Methods for Environmental Data

Outliers are an inevitable concern that needs to be identified and dealt with whenever one analyzes a large data set. Today’s water quality data are often collected on different scales, encompass several sites, monitor several correlated parameters, involve a multitude of individuals from several agencies, and span over several years. As such, the ability to identify outliers, which may affect the results of the analysis, is crucial. This note presents several statistical techniques that have been developed to deal with this problem, with particular emphasis on robust multivariate methods. These techniques are capable of isolating outliers while overcoming the effects of masking that can hinder the effectiveness of common outlier detection techniques such as Mahalanobis distances (MD). This note uses a comprehensive national metadata set on lake water quality as a case study to analyze the effectiveness of three robust outlier detection techniques, namely, the minimum covariance determinant (MCD), the minimum volume ellipsoid (MVE), and M-estimators. The note compares the results generated from these three techniques to assess the severity of each method when it comes to labeling observations as outliers. The results demonstrate the limitations of using MD to analyze multidimensional water quality data. The analysis also highlighted the differences between the three robust multivariate methods, whereby the MVE method was found to be the most severe when it came to outlier detection, while the MCD was the most lenient. Of the three robust multivariate outlier detection methods analyzed, the M-estimator proved to be the most flexible because it allowed for downweighting rather than censoring many borderline outlier observations.     

A Phosphorimeter for Measurements of Triplet Diffusion

ABSTRACT

A phosphorimeter is described which is intended to be used for delayed fluorescence measurements in which the excitation light is introduced in a spatially nonhomogeneous manner. The excitation optics produce a reduced image of the space intermittency pattern at a 1 mm layer of the test solution. The delayed emission is isolated from prompt fluorescence by an adjustable phasing between excitation and emission choppers. Solutions of anthracene and 9, 10-diphenyl anthracene in ethanol both show changes in delayed fluorescence intensity with changing dimensions of the space intermittency pattern. The effects observed are in agreement with theoretical expectations.     

Focused ion beam-scanning electron microscopy on solid-oxide fuel-cell electrode: Image analysis and computing effective transport properties

In the present work, microstructural and transport properties of a three-dimensional (3D) microstructure of lanthanum strontium manganite (LSM) are deduced using dual-beam focused ion beam-scanning electron microscopy (FIB-SEM) facility. A series of two-dimensional (2D) cross-sectional images are collected from the LSM sample using FIB-SEM and then reconstructed to 3D structures from the 2D images in a systematic approach. For the first time, the effect of different image processing steps including threshold value, median filter radius, morphological operators, surface triangulation, smoothing filter, etc., on porosity, internal surface area, electronic conductivity and diffusivity are studied. Variation of 33% and 25% on porosity ? and internal surface area S, respectively is observed because of improper selection of threshold value, median filter radius, and morphological operator. The number of triangular surfaces used in 3D reconstructions also varied the porosity ? and internal surface area S by 14.5% and 4.4%, respectively.Computational domains for calculating effective transport properties are generated using body-fitted cut-cell based finite volume meshes on reconstructed 3D volumes. The normalized effective transport properties are computed on computational domains reconstructed by the FIB-SEM as well as by a numerical model. For the FIB-SEM reconstruction case, the normalized effective properties in z-direction are 25-44% smaller than those properties in x and y directions. This difference is significant and reveals the anisotropy in FIB-SEM reconstructed volume compared to numerically reconstructed volume. The presence of large crater, milling direction and smaller 3D FIB-SEM reconstructed volume could be the main reasons for this local anisotropy.     

Molten Salt Catalysis of Gas Reactions

Molten salts have been used for many centuries in metal extraction, glass manufacture, and, more recently, in applications such as fused salt electrolysis. Usually dissociated into ions, they are often good solvents for oxides, carbides, nitrides, and metals. Their high thermal stability, low vapor pressure, good thermal and electrical conductivity, and low viscosity may be expected to confer on them an increasing technological importance in the future, and as a result research on their physical and chemical properties has grown markedly in recent years. Thermodynamic and transport properties [l-41 have been surveyed within the last decade, and Sundermeyer [5] has also reviewed their use as reaction media. A selection of catalytic reactions has been discussed by Kenney [6].