Cooperative Converters in Power Electronic Systems

ABSTRACT: The specifications of power electronic systems are becoming ever more exigent -better performance (dynamic and steady state), increased efficiency, reliability, and quality, and decreased power rating, size (volume and weight), and cost. One strategy for the overall improvement of these systems is to use various cooperating converters with the system functions being shared among them, optimizing each converter for the functions assigned it. The result will be a converter with better characteristics than a conventional design based on a single converter (or on a simple parallel association of converters) responsible for all the functions assigned to the system. This paper analyzes the possibilities of such cooperative converters, considering the filtering inductor size, and the efficiency, reliability, and power rating

High pressure and high temperature volumetric properties of (2-propanol + di-isopropyl ether) system

New experimental density data are reported for binary mixtures of 2-propanol + di-isopropyl ether over the composition range (6 compositions; 0.15 ≤ 2-propanol mole fraction x ≤ 0.85), between 293.15 and 393.28 K, and for 23 pressures from 0.1 MPa up to 140 MPa. Measurements were performed by means of an Anton Paar vibrating tube densitometer, calibrated with an uncertainty of 7 × 10−4 g cm−3. A Tait like equation was used to fit the experimental density data, with low standard deviations. Excess volumes have been calculated from the experimental data and fitted by the Redlich–Kister equation. Moreover, the isothermal compressibility and the isobaric thermal expansivity have been derived from the Tait-like equation.Ministerio de Ciencia e Innovación, Spain, Project ENE2009-14644-C02-0

Insuficiencia respiratoria neonatal asociada a mutación en el gen de la proteína C del surfactante

La insuficiencia respiratoria en el recién nacido a término durante las primeras semanas de vida extrauterina es una situación poco frecuente. Entre sus causas se incluyen las enfermedades difusas del intersticio pulmonar, un grupo heterogéneo de enfermedades, la mayoría idiopáticas, caracterizadas por infiltrados difusos, alteraciones funcionales de tipo restrictivo y afectación del intercambio gaseoso. Una forma de enfermedad pulmonar intersticial que puede afectar a lactantes, niños o adultos jóvenes es la que se asocia al déficit congénito de proteínas B o C del surfactante pulmonar. En estos casos los procesos inflamatorios que evolucionan hacia la fibrosis pulmonar están precedidos por la acumulación de material proteináceo en el alvéolo. Se indagó la presencia de mutaciones en los genes de las proteínas B y C del surfactante en una familia española en la cual dos lactantes presentaron insuficiencia respiratoria progresiva desde el nacimiento, con alteraciones radiológicas y anatomopatológicas compatibles con enfermedad del intersticio pulmonar, y el padre refería historia de problemas respiratorios desde la infancia. Se encontró que los dos hermanos de esta familia afectados por la enfermedad presentaban una expresión anómala del precursor de la proteína C del surfactante y concentraciones muy bajas de proteína madura. Se describe además una mutación nueva en el gen que codifica la proteína C del surfactante y que cosegrega con la enfermedad en esta familia

Influence of Tunneled Hemodialysis-Catheters on Inflammation and Mortality in Dialyzed Patients

Older age and comorbidities in hemodialysis patients determines the use of tunneled catheters as vascular access despite their reported clinical and mortality disadvantages. This prospective matched study analyzes the impact of permanent catheters on inflammation and mortality in hemodialysis patients; We studied 108 patients, 54 with AV-fistula (AVF) and 54 with indwelling hemodialysis catheters (HDC) matched by sex, age, diabetes and time under renal-replacement therapy comparing dialysis efficacy, inflammation and micro-inflammation parameters as well as mortality. Cox-regression analysis was applied to determine predictors of mortality, HDC patients presented higher C-reactive-protein (CRP) blood levels and percentage of pro-inflammatory lymphocytes CD14+/CD16+ with worse dialysis-efficacy parameters. Thirty-six-months mortality appeared higher in the HDC group although statistical significance was not reached. Age with a Hazard Ratio (HR) = 1.06, hypoalbuminemia (HR = 0.43), hypophosphatemia (HR = 0.75) and the increase in CD14+/CD16+ monocyte count (HR = 1.02) were predictors of mortality; elder patients dialyzing through HDC show increased inflammation parameters as compared with nAVF bearing patients, although they do not present a significant increase in mortality when matched by covariates. Increasing age and percentage of pro-inflammatory monocytes as well as decreased phosphate and serum-albumin were predictors of mortality and indicate the main conclusions or interpretations

Microbial volatile emissions promote accumulation of exceptionally high levels of starch in leaves in mono- and di-cotyledonous plants

Trabajo presentado en la X Reunión de Biología Molecular de plantas, celebrada en Valencia del 8 al 10 de julio de 2010.Peer Reviewe

Excess Enthalpies of Binary and Ternary Mixtures Containing Dibutyl Ether, Cyclohexane, and 1-Butanol at 298.15 K

Experimental excess enthalpies of the ternary system dibutyl ether (DBE) + cyclohexane + 1-butanol and the corresponding binary systems at 298.15 K are reported. A quasi-isothermal flow calorimeter has been built and tested to make the measurements. All the binary and the ternary systems show endothermic character. The experimental data have been fitted using a polynomial equation for the binary and ternary systems. The values of the standard deviation indicate good agreement between the experimental results and those calculated from the equation.Ministerio de Educación y Ciencia, Spain, Projects ENE2006- 12620 and ENE2006-13349, and from the Consejería de Educación, Junta de Castilla y León, Spain, Project BU015A0

Waist circumference percentiles for Hispanic-American children and comparison with other international references

Introduction Waist circumference (WC) constitutes an indirect measurement of central obesity in children and adolescents. Objective To provide percentiles of WC for Hispanic-American children and adolescents, and compare them with other international references. Materials and methods The sample comprised 13 289 healthy children between 6 and 18 years coming from public schools of middle and low socioeconomic levels in different parts of Argentina, Cuba, Spain, Mexico, and Venezuela. The LMS method to calculate WC percentiles was applied. Sex and age differences were assessed using Student'sttest and ANOVA (SPSS v.21.0). Comparisons were established with references from the United States, Colombia, India, China, Australia, Kuwait, Germany, Tunisia, Greece, and Portugal. Results WC increases with age in both sexes. Boys show higher WC in P3, P50, and P97. Comparison of 50th and 90th percentiles among populations from diverse sociocultural and geographical contexts shows high variability, not all justified by the measurement method. Discussion and conclusions Specific WC percentiles for sex and age, and P90 cut-off points are provided; these values are potentially useful to assess central obesity in Hispanic-American adolescent children

Subscapular and triceps skinfolds reference values of Hispanic American children and adolescents and their comparison with the reference of Centers for Disease Control and Prevention (CDC)

Introduction: the assessment of the skinfold thickness is an objective measure of adiposity. Therefore, it is a useful tool for nutritional diagnosis and prevention of metabolic risk associated with excess fat in chilhood and adolescence. Objective: to provide percentiles of subscapular and triceps skinfolds for Hispanic American schoolchildren and compare them with those published by the Centers for Disease Control and Prevention (CDC) from United States, that it have been commonly used as a reference in most of these countries. Methods: subscapular and triceps skinfolds were measured in 9.973 schoolchildren 4-19 aged from Spain, Argentina, Cuba, Venezuela and Mexico with Holtain caliper with 0.2 mm accuracy. Percentiles were obtained with the LMS statistical method and were presented in tables divided in stages of 6 months and in curves graphics. The difference between Hispanic American and CDC mean values were provided for P3, P50 and P97 in mm and also were graphically represented. Results: skinfolds measurements obviously increased with age in both sexes but, in boys, this increase is much more marked in highest percentiles between 8 and 13 years; this maximum is reached earlier than what occurs in CDC reference. In both sexes, all percentiles analized in Hispanic American schoolchildren were higher than the CDC reference except P97 up to 10 or 13 years that was notably smaller. Conclusions: the skinfolds percentiles of Hispanic American children and adolescents differ from CDC that are usually used as reference. The values of subscapular and triceps skinfolds provided in this study, could be applied to populations of a similar ethnic background, especially in comparative studies of body composition