Artículos científicos
Recent Submissions
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Obtención de lignina y celulosa de residuos de maíz
(Universidad Nacional, Costa Rica, 1992-01-01)Mediante un método de pulpeo sencillo se obtuvo la lignina y la celulosa de tusa y olote de maíz con buenos rendimientos. Los estudios de termogravimetría mostraron que estas ligninas son térmicamente menos estables que ... -
Green Solvents in Carbohydrate Chemistry: From Raw Materials to Fine Chemicals
(American Chemical Society, 2015)In recent decades, there has been an increasing effort to reduce the use of fossil fuels and oil derivatives, to decrease environmental pollution, and to counteract global warming. The use of biomass as raw material is ... -
Preliminary study on health effects and their relation to volcanic gas emissions exposure. A case study of two active volcanoes in Costa Rica
(Universidad Nacional, Costa Rica, 2022-01-31)The objective of this research was to carry out a preliminary diagnosis of the relationship between volcanic gaseous emissions and health effects present among workers of the National System of Conservation Areas (SINAC) ... -
Identifying groundwater recharge connections in the Moscow (USA) sub-basin using isotopic tracers and a soil moisture routing model
(Springer, 2016)Globally, aquifers are suffering from large abstrac tions resulting in groundwater level declines. These declines can be caused by excessive abstraction for drinking water, irrigation purposes or industrial use. Basaltic ... -
Environmental contribution of Los Tajos wastewater treatment plant in the removal of physicochemical and microbiological pollutants
(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) ... -
Waste management
(Universidad Nacional, Costa Rica, 2022-01-31)The grease and oil trap systems (GOTS) of four university food service establishments (FSE) were assessed and treated to evaluate the potential use of the sludge collected to produce compost. The sludge collected from each ... -
Influence of iron oxide nanoparticles on the rheological properties of hybrid chitosan ferrogels
(Elsevier, 2009)Magnetite nanoparticles have been successfully synthesized in the presence of chitosan using an in situ coprecipitation method in alkali media. This method allows obtaining chitosan ferrogels due to the simul taneous ... -
Influence of the electrical interface properties on the rheological behavior of sonicated soy lecithin dispersions
(Universidad Nacional (Costa Rica), 2007)A significant effect, on the rheological behavior, due to the electrical properties of vesicles formed from concentrated soy lecithin dispersions have been studied in this work. The rheopectic behavior of concentrated soy ... -
Initial validation of ozone measurements from the High Resolution Dynamics Limb Sounder
(Advancing earth an space science, 2008)Comparisons of the latest High Resolution Dynamics Limb Sounder (HIRDLS) ozone retrievals (v2.04.09) are made with ozonesondes, ground-based lidars, airborne lidar measurements made during the Intercontinental Chemical ... -
Iridoids from the aerial parts of Verbena littoralis (Verbenaceae)
(Elsevier, 2004)The iridoids, 6S-hydroxy-8S-methyl-4-methylene-hexahydro-cyclopenta[c]pyran-3-one and 6S,9S-dihydroxy-8S-methyl-4- methylene-hexahydro-cyclopenta[c]pyran-3-one, were isolated from the aerial parts of Verbena littoralis. ... -
Isolation and Characterization of Nanocellulose Obtained from Industrial Crop Waste Resources by Using Mild Acid Hydrolysis
(Tech Science Press, 2018)Cellulose, microcrystalline cellulose and nanocellulose were prepared from three agricultural waste resources: pineapple leaf (PALF), banana rachis (BR), and sugarcane bagasse (SCB). Each waste resource was first converted ... -
Isotope hydrology of a tropical coffee agroforestry watershed: Seasonal and event-based analyses
(Wiley & Sons, 2018)Stable isotope variations are extremely useful for flow partitioning within the hydrologic cycle but remain poorly understood throughout the tropics, particularly in watersheds with rapidly infiltrating soils, such as ... -
Isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica
(Taylor & Francis, 2016)The linkage between precipitation and recharge is still poorly understood in the Central America region. This study focuses on stable isotopic composition in precipitation and groundwater in the northern mountainous ... -
Kinetics of anaerobic degradation of screened dairy manure by upflow fixed bed digesters: Effect of natural zeolite addition
(Taylor & Francis, 2009)The effect of the hydraulic retention time (HRT) on the performance of two up-flow anaerobic fixed bed digesters (UFAFBDs) packed with waste tire rubber (D1) and waste tire rubber and zeolite (D2) as micro-organism ... -
Kinetics of Isothermal Degradation Studies in Adhesives by Thermogra vimetric Data: Effect of Hydrophilic Nanosilica Fillers on the Thermal Properties of Thermoplastic Polyurethane-Silica Nanocomposites
(Recent Patents on Nanotechnology, 2008)The kinetics of thermal degradation process on thermoplastic polyurethanes (TPUs) adhesives with hydrophilic nanosilicas was studied using isothermal thermogravimetric analysis within the temperature range from 360 °C ... -
Maxonine, a novel alkaloid from Simira maxonii
(Elsevier, 1989)A novel alkaloid, maxonine, with an indole-pyrido-naphthyridine skeleton, has been isolated from . Its structure was elucidated on the basis of 2D NMR spectral data. A novel alkaloid, maxonine (1), with an indolepyrido-n ... -
Methane Dynamics in a Tropical Serpentinizing Environment: The Santa Elena Ophiolite, Costa Rica
(Universidad Nacional (Costa Rica), 2017)Uplifted ultramafic rocks represent an important vector for the transfer of carbon and reducing power from the deep subsurface into the biosphere and potentially support microbial life through serpentinization. This ... -
Neutralización del efceto hemorrágico inducido por veneno Bothrops asper (Serpentes: Viperidae) por extractos de las plantas tropicales
(Universidad Nacional (Costa Rica), 1999)Organic extracts representing 48 species included in 30 families of Costa Rican tropical plants were evaluated for their hability to neutralize hemorrhagic acfivity lnduced by the venom of the snake Bothrops aspero Abioassay ... -
Obtención de acetato de celulosa a partir de desechos agroindustriales
(Universidad Nacional [Costa Rica], 1989-01-01)El propósito del presente trabajo fue encontrar usos alternativos para los residuos agrícolas. Se realizó la acetilación de celulosa de cáscara de piña, cáscara de arroz y aserrín. La reacción de acetilación se llevó a ... -
Evaluación química y biológica del efecto de extractos de plantas contra Plasmodium berghei
(Universidad de Costa Rica, 1996)Extracts from thirteen species of plants were evaluated by "in vivo" antimalarial test against Plasmodium berghei effects. Significant activities were observed in the ethyl acetate and aqueous extracts, elaborated of ...
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