Química: Envíos recientes
Mostrando ítems 1-20 de 125
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Aprovechamiento de los desechos de la industria del anodizado de aluminio en la síntesis de zeotipos tipo AlPO4-X y aplicación de estos en la captura de amoniaco
(2020)La finalidad de este trabajo fue llevar a cabo la síntesis de zeotipos tipo AlPO4-X utilizando desechos provenientes de la industria de anodizado de aluminio (DAAl-1) en sustitución de la fuente de aluminio, estos desechos ... -
Nickel-iron catalysts for electrochemical water oxidation – redox synergism investigated by in situ X-ray spectroscopy with millisecond time resolution
(2018)In future technological systems for chemical storage of renewable energy and production of non-fossil fuels, NiFe oxyhydroxides are prime candidates for efficient alkaline water oxidation (oxygen evolution reaction, OER). ... -
Structural and functional role of anions in electrochemical water oxidation probed by arsenate incorporation into cobalt-oxide materials
(2019)Direct (photo)electrochemical production of non-fossil fuels from water and CO2 requires water-oxidation catalysis at near-neutral pH in the presence of appropriate anions that serve as proton acceptors. We investigate the ... -
Heterogeneous Water Oxidation: Surface Activity versus Amorphization Activation in Cobalt Phosphate Catalysts
(2015)Is water oxidation catalyzed at the surface or within the bulk volume of solid oxide materials? This question is addressed for cobalt phosphate catalysts deposited on inert electrodes, namely crystallites of pakhomovskyite ... -
Influence of bitumen and aggregate polarity on interfacial adhesion
(2017)The quality of the bitumen–aggregate interface formed in an asphalt mixture is dictated by the physicochemical properties of both materials, such as surface polarity. In order to better understand the role of polarity on ... -
Superoxide dismutase based biosensor for the electrochemical determination of epinephrine
(2018)New amperometric biosensor for epinephrine was developed, using a screen printed carbon electrode with tetrathiafulvalene (5% v/w) incorporated into carbon ink (SPCTTFE). Electrodic surface was modified with nanoparticles ... -
Synthesis and characterization of new mixed-valent Mn(II)/Mn(III) and mixed metal Ni/Mn complexes
(2015)Microwave assisted synthesis and bench-top reactions are compared for Mn and Mn/Ni reaction systems with substituted salicylic acid (2-hydroxy-6-isopropyl-3-methylbenzoic-acid (SALOH2). When Mn salts are used, the microwave ... -
Biosensor for Aluminum(III) Based on α-Chymotrypsin Inhibition using a Disposable Screen-Printed Carbon Electrode and Acetyl-Tyrosine Ethyl Ester as Substrate
(2015)We report on a new amperometric assay for Al(III) ions based on the inhibition of α-chymotrypsin enzyme. The immobilization of the enzyme was performed on screen-printed carbon electrodes modified with gold nanoparticles ... -
Bile salts and derivatives: Rigid unconventional amphiphiles as dispersants, carriers and superstructure building blocks
(2015)Steroidal surfactants like bile salts have a rigid amphiphilic structure significantly different from the typical head–tail one. As a result, these molecules show peculiar features in their self-assembly behavior and ... -
A Chronoamperometric Screen Printed Carbon Biosensor Based on Alkaline Phosphatase Inhibition for W(VI) Determination in Water, Using 2-Phospho-l-Ascorbic Acid Trisodium Salt as a Substrate
(2015)This paper presents a chronoamperometric method to determine tungsten in water using screen-printed carbon electrodes modified with gold nanoparticles and cross linked alkaline phosphatase immobilized in the working ... -
Modified Laccase-Gold Nanoparticles-Tetrathiafulvalene-SPCEs Based Biosensor to Determine W(VI) in Water
(2017)It was developed an amperometric biosensor to determine tungsten in water, based on the inhibition of laccase enzyme, by tungsten ions using pyrocathecol as a substrate. The enzyme was immobilized with a proper mixture ... -
Influence of nanosilica and diatomite on the physicochemical and mechanical properties of binder at unaged and oxidized conditions
(2016)Modification of binders helps address common distresses in pavements by changing their essential properties. In order to further characterize the role of additives in these changes, a set of nanosilica and diatomite modified ... -
Caracterización estructural de vesículas modificadas con quitosano
(2018)Vesículas a base de L-α-fosfatidilcolina (PC) y mezclas de PC/fosfogliceroles fueron caracterizadas por medio de dispersión de luz dinámica (DLS), microscopía electrónica de barrido-criogénico (Cryo-SEM) y calorimetría de ... -
The Bacterial Product Violacein Exerts an Immunostimulatory Effect Via TLR8
(2019)Violacein, an indole-derived, purple-colored natural pigment isolated from Chromobacterium violaceum has shown multiple biological activities. In this work, we studied the effect of violacein in different immune cell lines, ... -
Essential oils of Baccharis trinervis (Asteraceae) from Costa Rica
(2017)Baccharis is an Asteraceae genus of flowering plants, which has about 340 to 400 species, ranging from the Southern United States to the Southern extreme of Argentina and Chile through Central America and the Caribbean ... -
Essential oil from leaves of Myrcianthes fragrans (Myrtaceae) from Costa Rica. A new chemotype?
(2017)Myrcianthes is a Myrtaceous genus of flowering plants of about 30 to 40 species, distributed in the American continent. The aim of this work was to study the chemical composition of the foliar essential oil from M. fragrans ... -
Aceptación de un jugo de mora endulzado con estevia en contraste con otros edulcorantes
(2017)El objetivo de la presente investigación fue desarrollar un jugo de mora (Rubus adenotrichus), endulzado con esteviolglucósidos (glucósidos obtenidos a partir de las hojas de Stevia rebaudina Bertoni) como una bebida ... -
Desarrollo de una metodología tropicalizada de gestión de la calidad orientada a las funciones administrativas que se ejecutan en la Escuela de Química de la Universidad de Costa Rica
(2019)El presente trabajo de investigación surge como una necesidad aparente que tienen las universidades (e instituciones públicas en general) por contar con una metodología de mejora sistemática, eficiente, de alta calidad y ... -
Bioassay-guided isolation of anti-inflammatory O-sulfated withanolides from Acnistus arborescens (Solanaceae)
(2019)Bioassay-guided fractionation of Acnistus arborescens (Solanaceae) organic extract afforded two anti-inflammatory withanolides: 2,3-Dihydro-3β-O-sulfate withacnistin (1) and 2,3-Dihydro-3β-O-sulfate withaferin A (2) showing ...