Browsing Artículos científicos by Title
Now showing items 142-161 of 189
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Nanochitin: Chemistry, Structure, Assembly, and Applications
(ACS Publications, 2022)Chitin, a fascinating biopolymer found in living organisms, fulfills current demands of availability, sustainability, biocompatibility, biodegradability, functionality, and renewability. A feature of chitin is its ability ... -
National Inventory of Mercury Release into Different Environmental Sectors Estimated by United Nations Environment Programme (UNEP) Toolkit in Costa Rica
(United Nations Environment Programme (UNEP) Toolkit, 2017)This paper summarizes the national inventory of mercury released into all environmental sectors (air, water, land, impurity in products, general wastes and sector specific treatment/disposal) for the year 2008 in the country ... -
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 ... -
New advances in the method validation, extraction methods and measurement uncertainty for the determination of water-soluble hexavalent chromium in hydraulic cemen
(Elsevier, 2021)The quantification of Cr (VI) in the cement matrix is highly important, given the possibility of suffering illnesses including dermatitis, induced nasal carcinoma, and DNA damage produced by inhalation of and/or direct ... -
New advances in the method validation, extraction methods and measurement uncertainty for the determination of water-soluble hexavalent chromium in hydraulic cement
(Elsevier Ltd, 2021-04-20)The quantification of Cr (VI) in the cement matrix is highly important, given the possibility of suffering illnesses including dermatitis, induced nasal carcinoma, and DNA damage produced by inhalation of and/or direct ... -
Nutritional and bioactive composition of Spanish, Valencia, and Virginia type peanut skins
(Academic Press Inc., 2021-01-21)The aims of this study were to determine the proximate and amino acid compositions, mineral content, and fatty acid and proanthocyanidins (PAC) profiles of peanut skins (PS) from three varieties of peanuts. Proximate ... -
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 ... -
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 ... -
Obtención de xilosa a partir de desechos lignocelulósicos de la producción y proceso industrial de la piña (Ananascomusus)
(Universidad Nacional (Costa Rica), 2012)Los desechos lignocelulósicos de la producción de piña son una materia prima muy útil para la producción de xilosa por medio de hidrólisis, que a su vez, puede convertirse a xilitol. El objetivo de este trabajo fue ... -
Obtención potencial de polímeros biodegradables. Estudio de la disolución de la cáscara de piña en PEG
(Universidad Nacional (Costa Rica), 1995-10-27)Se determinaron las condiciones para disolver la cáscara de piña en polietilénglicol 400. Se utilizó un tamaño de partícula entre 125 y 150 micrómetros, una relación 1/1 en peso de sustrato/PEG, temperatura 225°C y un ... -
On the comparison between diafiltration and isothermal titration calorimetry: Determination of the amount of analytes bound to watersoluble polymers
(Elsevier Ltd, 2019)Aqueous systems composed of low molecular-weight species (LMWS) and water-soluble polymers (WSP) present important technological applications. Therefore, continuous advances on characterization techniques are crucial to ... -
Optimization of the Extraction of Antioxidant Compounds from Roselle Hibiscus Calyxes (Hibiscus sabdariffa), as a Source of Nutraceutical Beverages
(MDPI, 2023-03-14)Secondary metabolites from Hibiscus sabdariffa have been used to prevent different diseases. Roselle Hibiscus is known for being rich in phenolic bioactive compounds. The extraction conditions are directly related to the ... -
Orientation effect in poly (butylene succinate) fibers
(Polymers & Polymer Composites vol.11 no.1 51-56 2003, 2003)Fibers of poly (butylene succinate) (PBS) were prepared using a single screw extruder at various take-up speeds. Changes in fiber structure, morphology and physical properties were investigated using sonic velocity ... -
Perfil nacional de uso de mercurio en Costa Rica a la luz de la entrada en vigencia del Convenio de Minamata
(Universidad Nacional (Costa Rica), 2017)El mercurio es un metal cuya inadecuada gestión puede poner en riesgo la salud y el medio ambiente, y debido a que en el país no existe una herramienta que le permita establecer los controles para su gestión, se elaboró ... -
Physical, mechanical and hydration kinetics of particleboards manufactured with woody biomass (Cupressus lusitanica, Gmelina arborea, Tectona grandis), agricultural resources, and Tetra Pak packages
(Waste Management and Research vol.32 no.2 106-114 2014, 2014-02-11)Lignocellulosic wastes resulting from agricultural activities as well as Tetra Pak residues from urban centres can cause significant levels of pollution. A possible action to minimize this problem is to use them in the ... -
Physicochemical and chromatographic method of characterization of Matricaria recutita tinctures
(2016)The pharmacological activity of medicinal products containing plant materials depends on their specific components. However, these components are not characterized in their entirety in all cases. Therefore, manufacturing ... -
Phytonutraceutical evaluation of five varieties of tomato (Solanum lycopersicum) during ripening and processing
(Elsevier, 2022-07-15)Tomato (Solanum lycopersicum) is the largest produced vegetable in the world after potato and sweet potato. It is an important source of carotenoids (mainly lycopene), ascorbic acid, and phenolic compounds. In this work, ... -
Potencial del cultivo de hongos comestibles en Costa Rica
(Editorial de la Universidad Nacional, 1985-01-01)Sin lugar a duda la ubicación de Costa Rica es un privilegio desde el punto de vista ecológico. La gran diversidad de zonas de vida que existe permite cultivar una gran cantidad de vegetales, entre estos los hongos. Estas ... -
Potent CYP3A4 Inhibitors Derived from Dillapiol and Sesamol
(American Chemical Society 4, 6, 10915–10920 2019, 2019)Synthesis of 50 analogues of the natural insecticide synergists, dillapiol and sesamol, is reported. These were evaluated as potential insecticide synergists based on their inhibition of human CYP3A4. The most potent ... -
Preface to Stable isotopes in hydrological studies in the tropics: ecohydrological perspectives in a changing climate
(Wiley & Sons, 2019)Tropical regions (comprised between the Tropics of Cancer and Capricorn, 23.5°N to 23.5°S) cover approximately 36% of the Earth's landmass. They are home to 40% of the world's population, which is projected to increase ...