Voltammetric behaviour of the copper(II)—thiourea system in sulphuric acid medium at platinum and glassy carbon electrodes

Thiourea, a levelling agent used in copper electrorefining baths, is the focus of a cyclic and rotating disc or ring-disc electrode voltammetric study. Thiourea adsorption, its interaction with Cu²⁺ and formation of Cu(Tu) _n ⁺ complexes are part of the multistep electrode mechanism proposed. Results at platinum and glassy carbon electrodes are applicable to copper electrodes in electrorefining.     

Control Charts with Variable Dimension for Linear Combination of Poisson Variables

This article analyzes the simultaneous control of several correlated Poisson variables by using the Variable Dimension Linear Combination of Poisson Variables (VDLCP) control chart, which is a variable dimension version of the LCP chart. This control chart uses as test statistic, the linear combination of correlated Poisson variables in an adaptive way, i.e. it monitors either p₁ or p variables (p₁ < p) depending on the last statistic value. To analyze the performance of this chart, we have developed software that finds the best parameters, optimizing the out‐of‐control average run length (ARL) for a shift that the practitioner wishes to detect as quickly as possible, restricted to a fixed value for in‐control ARL. Markov chains and genetic algorithms were used in developing this software. The results show performance improvement compared to the LCP chart. Copyright © 2015 John Wiley & Sons, Ltd.     

Growth in height of indigenous and non indigenous Chilean children

The aim of this study was to compare growth curves of stature in indigenous and non-indigenous children belonging to two levels of poverty and to establish the onset and evolution of the deficit. Children of indigenous and non-indigenous background living in communities of extreme and low poverty in Chile were studied and their height-for-age Z-score from birth until 6 year of age were compared. Mean weight at birth was within normal range, and no differences were found in ethnicity and levels of poverty. Length at birth was below the reference with the exception of the non indigenous newborn from counties of low poverty. Deficit in growth showed an early start, furthermore in indigenous children belonging to the extreme poverty, is from birth and progress through the 18 months. At 72 months the deficit reached -1.1 z scores in the indigenous of the extreme poverty versus -0.7 in the non indigenous group. Children from the low poverty had a Z-score of -0.4 z scores at 72 months without differences between ethnias. Indigenous of the extreme poverty had less accumulative growth while the indigenous of the low poverty areas growth satisfactory without differences with the non indigenous.     

Heat flow in copper converters

A mathematical heat flow model has been developed to quantify the influence of out-of-stack time and other variables on the temperature distribution in the refractory wall of copper converters. Factors such as diameter of the converter, size and position of the converter mouth, and the use of a mouth cover have been studied with the model, in order to relate converting practice to operating problems. The results of the model indicate that when the converter is out of the stack, heat losses through the mouth of the converter cause the internal refractory surface to cool rapidly which may lead to freezing at the tuyere line and tuyere blockage when blowing is resumed. The temperature gradient, localized to within 60 to 80 mm of the refractory inside wall, changes markedly within the first minutes of the converter being out of the stack. This may generate thermal stresses in the converter wall and contribute to refractory erosion at the tuyere line. Covering the converter mouth during out-of-stack periods significantly reduces the change in temperature gradient at the inside wall as well as heat losses from the converter. Formerly Graduate Student     

Electrical Behavior and Technology Optimization of Si/SiGeC HBTs on Thin-Film SOI

A growing interest has been focused on silicon on insulator (SOI) technologies over the past years. Yet, few studies were carried out regarding the integration of vertical SiGe heterojunction bipolar transistors (HBTs) using such substrates. This paper deals both with the integration of a SiGeC HBT on thin-film CMOS-compatible SOI, and a comprehensive study of its electrical behavior based on physical simulation and electrical characterization. Various aspects of the optimization of device performances are described, considering process or layout improvements.     

DNA barcoding to confirm morphological traits and determine relative abundance of burrowing mayfly species in western Lake Erie

Burrowing mayfly species of the genus Hexagenia are well known indicators of environmental health in lakes and rivers. Two species, H. limbata and H. rigida, are indistinguishable as nymphs and as adult females. Our objectives were to develop a genetic technique to distinguish between the two species and identify morphological features that separate cryptic nymphs and adult females. Fifty nymphs were collected before emergence from 10 sites throughout the western basin of Lake Erie in 2004 and 2005. Using known specimens of adult aerial male H. limbata and H. rigida, we used the mitochondrial cytochrome c oxidase subunit 1 (COI) gene to identify a 16 base pair (bp) difference between species. DNA sequencing confirmed correct species identification based on differences in abdominal pigmentation patterns on adult female imagos in 19 of 20 cases; the lone exception was a female with very faint pigmentation. Pigmentation patterns between species were consistent on nymphs, subimagos and imagos of both sexes. Populations of both species are panmictic across the western basin of Lake Erie, but H. limbata is the numerically dominant species, representing 70 to 100% of nymphs at sites in both years. A separate lineage of H limbata was discovered in the samples. The ability to distinguish nymphs of the two species will aid in developing more sensitive ecosystem indicators.     

Eating characteristics of Chilean indigenous and non-indigenous adolescent girls

During childhood and adolescence, eating habits become established which are instrumental in determining eating behavior later in life. Various authors have described the acculturation of the Mapuche people toward Western culture. The objective of this study was to analyze the eating characteristics of indigenous and non-indigenous adolescent girls in the Araucania Region of Chile. A cross-sectional design was used with a probabilistic sample of 281 adolescents comprised of 139 indigenous and 142 non-indigenous girls attending 168 elementary schools. A modified food frequency questionnaire was applied, designed to obtain information about eating habits and consumption of Mapuche foods. The eating schedules are similar in both ethnic groups, with dinner being the meal that is least consumed. Total snack consumption per week has a mean of 7 with an interquartile range (IQR) of 5 to 10 without any differences between ethnic groups; of these snacks, only 2 were healthy (IQR = 1 to 3). The indigenous girls had a higher probability of consumption of native foods including mote (boiled wheat) (OR = 2.00; IC = 0.93-4.29), muday (fermented cereal alcohol) (OR = 3.45; IC = 1.90-6.27), and yuyo (field mustard) (OR = 4.40; IC = 2.06-9.39). The study's conclusion is that the the eating habits and behavior of indigenous adolescents are similar to those of non-indigenous girls, though the former still consume more indigenous foods.