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"Degradation"
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Behavior of BaCe0.9ax Zr x Y0.1O3aI' in water and ethanol suspensions
The stability of perovskite proton conductors BaCe0.2Zr0.7Y0.1O2.95 and BaCe0.5Zr0.4Y0.1O2.95 (referred to as BCZY) has been tested by exposure of powders to water and ethanol at room temperature. The liquid phase was monitored as a function of time with inductively coupled plasma-optical emission spectrometry. With water, leaching of barium continued for over 200 days, the duration of the test. There was no systematic difference in leaching with solutions of native pH or alkalified with NH4OH. The powders, before and after treatment, were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM confirmed the degradation of the perovskite phase and revealed barium carbonate nanobranches and nanoparticles from the agglomeration of the fragmented perovskite. The effect of ethanol was much less severe; leaching of elements after immersion was negligible for up to 17 days, and XRD patterns before and after treatment did not show any structural degradation. It is concluded that ethanol is an appropriate choice as a processing solvent for tapecasting BCZY powders.
Journal Article
Kinetic model study of moisture sorptionadesorptionaresorption in triangular-shaped vinyl ester filler/epoxy composites
A phenomenological diffusion model was used to study and describe moisture sorptionadesorptionaresorption kinetics in triangular-shaped vinyl ester filler/epoxy composites at 80 degree C. The model was derived to predict the experimental anomalous weight gain behaviors of epoxy composites during moisture sorption and resorption, and estimate the degree of material degradation and loss observed as negative weight change during desorption. To verify the applicability of the model, acid anhydrideacured epoxy composites were prepared at varied alignment (parallel or staggered), spacing (1 or 5 mm), and orientation (pointed or flat) of triangular-shaped vinyl ester fillers. Moisture sorptionadesorptionaresorption experiment was performed by immersion of specimens in deionized water for 1200 h, followed by vacuum drying for 300 h, and water reimmersion for 300 h. The parameters of the model were calculated from nonlinear regression of percent weight change versus time experimental data. The model was found to be in good agreement with the weight change kinetic curves of all specimens. Results of three-way analysis of variance of model parameters showed the degree of material degradation and moisture diffusion coefficients during sorption, desorption, and resorption to be significantly affected by triangular-shaped filler alignment, spacing, and orientation. Using staggered over parallel alignment and 5-mm over 1-mm spacing decreased material degradation and moisture transport rate during desorption in composites. Increasing the spacing from 1 to 5 mm decreased moisture diffusion during sorption. Orienting the fillers from pointed to flat decreased moisture diffusion during resorption. Effect of interaction of filler spacing and orientation was also found to be statistically significant on the diffusion rate during sorption.
Journal Article
Mercury, Mining, and Empire
On the basis of an examination of the colonial mercury and silver production processes and related labor systems, Mercury, Mining, and Empire explores the effects of mercury pollution in colonial Huancavelica, Peru, and Potosí, in present-day Bolivia. The book presents a multifaceted and interwoven tale of what colonial exploitation of indigenous peoples and resources left in its wake. It is a socio-ecological history that explores the toxic interrelationships between mercury and silver production, urban environments, and the people who lived and worked in them. Nicholas A. Robins tells the story of how native peoples in the region were conscripted into the noxious ranks of foot soldiers of proto-globalism, and how their fate, and that of their communities, was-and still is-chained to it.
eBook
Novel Bi sub(2)WO sub(6) flower type structure controllable synthesis and enhanced visible photocatalytic degradation performances
Novel Bi sub(2)WO sub(6) flower type structure has been successfully synthesized by simple hydrothermal processes. Interestingly, the morphologies and sizes of the Bi sub(2)WO sub(6) were controlled by pH values. X-ray diffraction, FT-IR, scanning electron microscope, transmission electron microscope, BET, and UV-visible diffuse reflectance spectra were used to characterize the flower type structure. The results indicated that the Bi sub(2)WO sub(6) composed of some uniform slice with side length about 100 nm. The as-prepared Bi sub(2)WO sub(6) photocatalysts had excellent photocatalytic activity for the degradation of nitrobenzene under visible light ( lambda greater than or equal to 400 nm).
Journal Article
Model of hot-carrier degradation for lateral IGBT device on SOI substrate
A novel model for hot-carrier degradation in a lateral insulated gate bipolar transistor (IGBT) device on SOI substrate (SOI-LIGBT) is presented. The setup of the model is based on the existing hot-carrier degradation mechanism in a SOI-LIGBT and assisted by a lateral DMOS device on SOI substrate (SOI-LDMOS) with completely the same structure except for the doping type in the drain area. The model parameters have been extracted by the degradation measurement results and the validity of the proposed model in a SOI-LIGBT has been also verified. [PUBLICATION ABSTRACT]
Journal Article