Resumen Conocido originalmente por sus efectos deletéreos en la salud, recientemente se ha reconocido al sulfuro de hidrógeno (H2S) como un gasotransmisor de importancia biológica, al igual que el óxido nítrico y el monóxido de carbono. El H2S puede producirse de forma endógena en las células de mamíferos por dos vías: la vía enzimática y la vía no enzimática. Cuando se produce por la vía enzimática, su síntesis se lleva a cabo a partir de los aminoácidos L-cisteína o metionina mediante transulfuración y transmetilación. También se puede producir el H2S a partir donadores de grupos sulfuro como, por ejemplo, compuestos orgánicos que se encuentran presentes en algunos vegetales. Actualmente es bien conocido el papel del H2S como protector a nivel cerebral y cardiaco, y cada vez adquiere mayor relevancia su estudio como coadyuvante terapéutico en padecimientos metabólicos como la obesidad y la diabetes mellitus de tipo 2. El objetivo de esta revisión es examinar cómo impacta el aporte de donadores y precursores del sulfuro de hidrógeno por la dieta en la salud y la enfermedad.

Abstract Initially known for its deleterious health effects, hydrogen sulfide (H2S) has recently been recognized as a biologically important gas carrier, like nitric oxide and carbon monoxide. H2S is produced endogenously in mammalian cells by enzymatic and non-enzymatic pathways. When it is produced by the enzymatic pathway, its synthesis is carried out from the amino acid L-cysteine through the transsulfuration pathway. It can also be produced endogenously from exogenous compounds that function as H2S donors as, for example, the naturally occurring organic donors found in some plants. Currently, the role of H2S is well known as brain and cardiac protector, and its research as a therapeutic adjuvant in metabolic diseases such as obesity and type-2 diabetes is becoming increasingly important. The objective of this review is to examine how the contribution of donors and precursors of hydrogen sulfide by the diet impacts health and disease.

RESUMEN A partir de visualización por electroforesis capilar de 9 regiones micro-satélites amplificadas con cebadores fluoromarcados se determinó el polimorfismo de los marcadores Hmct5, 102, HV 30, 548, HV 15, 416, m574, 103 y 358 identificados en el ADN de muestras de tejido foliar de 12 clones de caucho (Hevea brasiliensis) conservados en jardines clonales de AGROSAVIA en Colombia y 25 clones en jardines clonales de origen en Brasil. Con base en los resultados del análisis se consolidó una base de datos que permite corroborar la identidad por conformidad de clones de caucho a partir de muestras foliares. El protocolo establecido consiste en una aproximación metodológica para la amplificación de dichas regiones micro-satélites por PCR punto final y la visualización de los fragmentos obtenidos de este procedimiento por electroforesis capilar multiplexada, reduciendo costos y optimizando el tiempo en laboratorio. Adicionalmente se encontraron discrepancias entre el perfil electroforético obtenido del clon FX 3864 muestreado en Colombia con el obtenido en Brasil. Se propone considerar la necesidad de corroborar la identidad de los clones reproducidos en jardines clonales para su comercialización en Colombia, utilizando metodologías sensibles y reproducibles, como la estandarizada en este estudio.

ABSTRACT The polymorphism of 9 regions identified in the DNA of leaf tissue sampled from 12 rubber clones conserved in clonal gardens of AGROSAVIA in Colombia and 25 clones in clonal gardens of origin in Brazil was visualized by capillary electrophoresis after amplification with the fluorolabeled primer microsatellite markers Hmct5, 102, HV 30, 548, HV 15, 416, m574, 103 and 358. Upon the results analysis, a database was consolidated that allows to corroborate the genetical identity by conformity with 37 rubber clones from leaf samples. The established protocol is a methodological approach using end-point PCR towards the amplification by multiplexed capillary electrophoresis of micro-satellite regions and their visualization, reducing costs and optimizing time in the laboratory. Additionally, discrepancies were found between the electrophoretic profile obtained from clone FX 3864 sampled in Colombia with that obtained in Brazil. It is proposed to consider the need to corroborate the identity of the clones reproduced in clonal gardens for their commercialization in Colombia, using sensitive and reproducible methodologies, such as the one standardized in this study.

Poisson's ratio and birefringence, both measured by ultrasound, are used to follow the evolution of the anisotropy in ASTM A-36 steel plates cold-rolled between 5 and 50% deformation, and then subjected to recrystallization at 900 and 1000 ºC. Times of flight of longitudinal and shear waves along the thickness of the plates were measured. As orthotropy increases, both birefringence and the difference between Poisson's ratios measured using a shear wave polarized along the length and another wave polarized along the width of the plate, are linearly related to the degree of deformation and cold-rolled hardness. In addition, the ultrasonic methods used clearly detected the complex changes in anisotropy produced by the austenization and recrystallization heat treatments. Thus, Birefringence or Poisson's ratio, measured by ultrasound, can be used to follow-up nondestructively changes in the anisotropy of rolled plates as a function of both, degree of deformation and recrystallization heat treatment.

This study investigates students' conceptions of evaporation, condensation and vapor pressure that are Physical Chemistry basic concepts. Chemical Engineer and Industrial Chemistry major students were questioned on three tasks that had been designed around these topics. Qualitative analysis of student responses according to Robson's method showed a range of conceptions in each area, including some misconceptions. The implication in the teaching-learning process is that observation of physical chemistry phenomena is not enough. On the contrary, it is necessary to give time to students for reflection and to debate their hypothesis and conceptions.