No abstract

Most of radio controlled cars with Fuel Cell on the market store hydrogen in pressurized cylinders or metal hydrides. In this article, the possibility of generating hydrogen inside the vehicle, at a constant flow rate, from aluminum soda can rings, in alkaline solution medium and by isopropyl alcohol regulation, is proposed. The alcohol helps to eliminate the NaOH particles transported by the hydrogen and likewise to keeps the flow rate constant over time. A theoretical model has been developed to predict the hydrogen flow rate generated as a function of the molarity and temperature of the solution, as well as the purity and dimensions of the aluminum plates. Subsequently, the model has been validated experimentally from test plates and the flow rate and purity of the hydrogen obtained has been analyzed. Finally, a radio control car with Fuel Cell was designed, adding the filters and elements necessary for its correct operation. Main contribution of this study is the use of isopropyl alcohol for flow rate regulation and the control of the purity of hydrogen.

A Zona Costeira Maranhense apresenta uma variedade de ecossistemas de grande importância ambiental e nela encontra-se a baía de São José, situada ao nordeste do Maranhão, fazendo parte de um dos grandes complexos estuarinos que formam o Golfão Maranhense. A alta produtividade biológica deste ambiente deve-se principalmente ao fitoplâncton, por constituir a base da teia trófica dos ecossistemas aquáticos. Dessa forma, este estudo teve como objetivo avaliar a composição do fitoplâncton na região costeira do Caúra, São José de Ribamar - MA. Quatro campanhas amostrais foram realizadas nos períodos de pico da estiagem (PE), início da chuva (IC), pico da chuva (PC) e início da estiagem (IE), em três pontos amostrais. Para as variáveis ambientais, as amostras foram coletadas na sub-superfície da água e aferidas com o multiparâmetro, refratômetro e disco de Secchi. Amostras qualitativas do fitoplâncton foram realizadas com auxílio de rede cônico-cilíndrica. Para as análises quantitativas foi utilizada a técnica de sedimentação, transectos em cruz no microscópio invertido. A clorofila a foi analisada através do método espectrofotométrico. 81 táxons foram registrados no Caúra, com predomínio da divisão Bacillariophyta. Quanto ao índice de constância, as espécies que se destacaram em 100% das amostras foram Synedra tabulata, Synedra sp2, Coscinodiscus oculus-iridis e Coscinodiscus sp. A análise da clorofila a revelou valores maiores no pico da estiagem, enquanto a densidade apresentou-se maior durante o pico da chuva. A Análise dos Componentes Principais mostrou que a densidade fitoplanctônica correlacionou-se positivamente com o nitrogênio total e a amônia e negativamente com a salinidade, o pH, o fósforo total e o microfitoplâncton. O ambiente mostrou-se muito produtivo, onde o manguezal e a praia estavam aparentemente saudáveis. Entretanto, na região portuária, a intervenção antrópica foi verificada devido a intensa movimentação de embarcações, ao tratamento de pescados e ao acúmulo de resíduos sólidos.

F IFTY years have elapsed since Dr. Hector Croxatto started his teaching and research work at the Catholic University of Chile, which he has continued without interruption until today. His unceasing scientific activity is reflected in more than 300 scientific communications and publications, and also in the activity of many of his collaborators who work in the fields of physiology, endocrinology, nephrology, and cardiology.In the early 1940s, Dr. Croxatto initiated a line of research on the mechanisms of arterial hypertension, which he has continued up to now. The first important contribution in this context was done in 1942 when he demonstrated that pepsin acted upon globulins of plasma generating a peptide, called pepsitensin, which showed properties very similar to angiotensin. This finding was important in explaining the genesis of angiotensin as the result of the proteolytic action of renin on blood globulins. It also opened a new concept: other peptides, which act upon the cardiovascular system, could be produced from plasma.The studies of Dr. Croxatto and his collaborators then took different directions when it became evident that the renin-angiotensin system and other peptides participated in actions other than simple arteriolar constriction. Thus, he carried out studies to compare the activity of renin and peptide hormones of neurohypophysis, vasopressin and ocytocin, on the renal function, especially in water and sodium excretion. The results of these investigations led him to foresee functional and structural differences between these peptides, which were confirmed years later by other researchers using more sophisticated techniques.The potent effects of peptides and their potential structural diversity led him, in 1960 when only few biologically active peptides were identified, to express: "It is not daring to foretell that in the near future the family of peptides will be enriched with new members . . . which will give rise to unpredictable biological properties."Professor Croxatto and his group provided in 1970 the first evidence that kallikrein excretion in urine, and later renal tissue kallikrein, were significantly decreased in rats with experimental renal hypertension. He demonstrated by using isolated perfused kidneys that urinary kallikrein originates in renal tissue.Particular attention has been devoted to factors that can regulate or modulate the renal kallikrein-kinin systems. In 1973, Professor Croxatto was the first to describe the remarkable effect of furosemide on that system in normal and hypertensive rats. His recent findings permit a better definition of the role of sodium, renin, prostaglandins, the endocrine system, and the autonomic nervous system as modulators of the renal kallikrein-kinin system and its relationship to hypertension. The fact that the kidney possesses two antagonist enzymatic systems that generate vasoconstrictor II-2 at California Institute of Technology on June 21, 2015 http://hyper.ahajournals.org/ Downloaded from

Introducción. La consanguinidad es la unión entre personas que comparten un ancestro en común, y cuya descendencia presenta un mayor riesgo de aparición de enfermedades autosómicas recesivas, manifestándose en algunos pacientes como trastornos del neurodesarrollo. Objetivos. Describir la consanguinidad parental no declarada en pacientes menores de 18 años con trastornos del neurodesarrollo, descubierta mediante el análisis cromosómico por micromatrices. Métodos. Se realizó el análisis cromosómico por micromatrices a 967 pacientes con trastorno del neurodesarrollo entre 2016 y 2021. Fueron seleccionados los pacientes con regiones de homocigosidad (ROH) con un valor superior a 0,5%. Resultados. Se evaluó a 288 pacientes, el 58,3% fueron varones y el 29,8% presentó una ROH mayor o igual a 0,5%. Se encontró que el 25,9% y el 0,83% de los pacientes tenían padres con un quinto y primer grado de consanguinidad no declarada, respectivamente. Los departamentos con mayor frecuencia relativa de consanguinidad no declarada por cada 10 000 habitantes fueron Huancavelica, Cajamarca y Apurímac. Conclusión. En Perú, existen regiones donde se evidencia uniones parentales consanguíneas, el cual es un factor de riesgo alto para la aparición de enfermedades recesivas autosómicas en su descendencia, como los trastornos del neurodesarrollo.