Browsing Artículos científicos by Title
Now showing items 1-20 of 187
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A methane sink in the Central American high elevation páramo: Topographic, soil moisture and vegetation effects
(Elsevier B.V., 2020-03-15)Methane (CH4) is a strong greenhouse gas with a global warming potential 23 times larger than that of carbon dioxide. Characterizing ecosystems as either sources or sinks for methane and their magnitudes informs on biosphere ... -
A preliminary isotope-based evapotranspiration partitioningapproach for tropical Costa Rica
(John Wiley and Sons Ltd, 2021-07)Spatially and seasonally distributed information on transpiration (T) fluxes is limited in the tropics. Here, we applied a coupled isotope mass balance model to separate water fluxes of T and evapotranspiration (ET) from ... -
A Selective Ion HPLC-APCI-MS Method for the Quantification of Pentacyclic Triterpenes in an Anxiolytic Botanical Dietary Supplement for the Animal Health Market
(Natural Product Incorporation, 2019)A new anti-anxiety dietary supplement was developed for the animal health market, by combining 2 triterpene containing botanicals, Souroubea sympetala (Marcgraviaceae) with Platanus occidentalis (Platanaceae) A validated ... -
Absorción de nutrientes a través de la hoja
(Universidad Nacional (Costa Rica), 2013)La fertilización foliar es una práctica efectiva para la corrección de deficiencias nutricionales en plantas que se encuentran bajo condiciones de estrés o en suelos con baja disponibilidad de nutrientes. ... -
Acercamiento a los procesos de modelación de la calidad del agua en una subcuenca. Caso del río Virilla, Costa Rica
(Universidad Nacional, Costa Rica, 2021-01-31)Se realizó la implementación de un modelo de calidad del agua superficial, a través del cual se procuraba hacer un primer acercamiento a los procesos de modelado matemático como insumo para la gestión integrada ... -
Addition of nanosilicas with different silanol content to thermoplastic polyurethane adhesives
(Elsevier, 2005-08-15)Three nanosilicas with different silanol contents were prepared by treatment of hydrophilic fumed silica with dimethyldichlorosilane. This treatment reduced the silanol content and produced the particle agglomeration of ... -
Amenazas químico-tecnológicas en la Gran Área Metropolitana de Costa Rica
(Universidad Nacional (Costa Rica), 2013)Los accidentes químico-tecnológicos son eventos inesperados que con llevan la liberación no controlada de una o más sustancias químicas con graves repercusiones en la salud humana y, en ocasiones, impactos irreversibles ... -
An anatomical comparison between bunch and fruit of oil palm with pineapple leaf and three woods from plantations in Costa Rica
(Journal of Oil Palm Research, 2013-04)Elaeis guineensis, Ananas comusus and forest plantations are planted widely in Costa Rica; however their residues (8000 t) are not utilised. The main objective of this work was to undertake an anatomical description of the ... -
An approach to rheological and electrokinetic behaviour of lipidic vesicles covered with chitosan biopolymer
(Elsevier, 2008)The rheological and electrokinetic properties of soybean lecithin vesicles prepared from concentrated soy lecithin dispersions (250 g/L) obtained by slow swelling under shear conditions and mixed with chitosan biopolymer ... -
An in vivo model to study the anti-malaric capacity of plant extracts
(Universidad de Costa Rica, 1998)An in vivo model to study the antimalaric effect of plant extracts is described. White mice (25-30g body weight) are treated subcutaneously with 0.6ml of the diluted extract starting seven days before P. berghei infection; ... -
Analysis of energy transfer and ternary non-covalent filler/matrix/UV stabilizer interactions in carbon nanofiber and oxidized carbon nanofiber filled poly(methyl methacrylate) composites
(Elsevier, 2011-10-27)Ternary non-covalent interactions between carbon nanofibers (CNFs), oxidized carbon nanofibers (ox- CNFs), poly(methyl methacrylate) (PMMA) chains, and benzotriazole-containing UV stabilizers were analyzed using ... -
Analysis of non-covalent interactions between the nanoparticulate fillers and the matrix polymer as applied to shape memory performance
(The Royal Society of Chemistry, 2010)Non-covalent interactions between filler particles and polyurethanes were investigated using fluorescence emission spectroscopy. The results were used in the analysis of shape memory (SM) performance of polyurethanes. ... -
Análisis de las Olimpiadas Nacionales de Química en Costa Rica: Alcances y retos para la población joven
(Universidad Nacional (Costa Rica), 2012)La Escuela de Química ha promovido programas y proyectos académicos como las Olimpiadas de Química que estimulen y mejoren el aprendiza-je de esta ciencia. Como competencia se identifican estudiantes de alto desempeño ... -
Análisis de los accidentes químico-tecnológicos presentados en la gran área metropolitana durante el período de 1998-2005
(Universidad Nacional (Costa Rica), 2010)Durante el periodo 1998-2005, la unidad de Materiales Peligrosos del Instituto Nacional de Seguros (MATPEL) atendió 329 emergencias químico-tecnológicas en Costa Rica, de las cuales 255 ocurrieron en la Gran Área Metropolitana ... -
Anthrone and oxanthrone C,O-diglycosides from Picramnia teapensis
(Elsevier, 2000)Two C,O-diglycosylated compounds, the anthrone picramnioside F, and the oxanthrone mayoside C, were isolated from the stem bark of Picramnia teapensis, along with the previously reported anthraquinones, 1-O-b-d- and ... -
Antimicrobial activities of Marcgraviaceae species and isolation of a naphthoquinone from Marcgravia nervosa (Marcgraviaceae)
(NRC Research Press, 2015)The Marcgraviaceae is a neotropical plant family of lianas and shrubs distributed throughout Central and South America, mainly in evergreen and semi-evergreen tropical forests. In this study, extracts of 12 Marcgraviaceae ... -
Antioxidant and antimicrobial activity of two Costa Rican cultivars of ber (Ziziphus mauritiana): An underexploited crop in the American tropic
(Wiley Periodicals LLC, 2023-03-17)Ber is an antioxidant-rich fruit from Asia and has recently been cultured in Central America. The antioxidant capacity and antimicrobial activity of Z. mauritiana cultured of bers from Guanacaste, Costa Rica, were evaluated. ... -
Aplicación de un método para evaluar el impacto ambiental de proyectos de construcción de edificaciones universitarias
(2016)La evaluación de impacto ambiental consiste en la identificación y valoración de los impactos potenciales de proyectos respecto a los componentes físicos, químicos y biológicos, culturales, económicos y sociales, con el ... -
Aporte ambiental de la planta de tratamiento de aguas residuales Los Tajos en la remoción de contaminantes fisicoquímicos y microbiológicos
(Universidad Nacional, Costa Rica, 2022-01-31)AbstractThe objective of the study was to analyze the environmental contribution, in terms of removal of physicochemical and microbiological pollutants, from the Los Tajos Wastewater Treatment Plant (WWTP) ... -
Application of a Sulfur Removal Hydrometallurgical Process in a Lead-Acid Battery Recycling Plant in Costa Rica
(Scientific Research Publishing Inc., 2017)This study presents the implementation of a desulphurization process for lead recycling under different chemical and physical conditions using pyro-metallurgical processes. Desulphurization was done using a hydrometallurgical ...
