Browsing Química by Title
Now showing items 99-118 of 170
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Light Reflection by Cuticles of Chrysina Jewel Scarabs: Optical Measurements, Morphology Characterization, and Theoretical Modeling
(2016)Cuticles of some Chrysina scarabs are characterized by flat, graded, and twisted structures of nanosized chitin fibrils. As inferred from SEM images, each species has its own spatial period or pitch P which is dependent ... -
Metales traza (As, Cd, Co, Cr, Ni, Pb) en plantaciones bananeras de Costa Rica y efecto del cromo en el crecimiento y la absorción de nutrimentos en plantas de banano (Musa AAA)
(2021)Los metales traza son elementos que se encuentran en bajas concentraciones en el ambiente, generalmente menores a mil partes por millón. Algunos de estos elementos son requeridos en el ciclo de vida ... -
Metals in coastal mollusks of Costa Rica
(2015-12)The input of contaminants to coastal ecosystems is a global problem on the rise. Data on metal pollution from tropical sites is often lacking and pilot surveys are urgently needed to provide a general framework to estimate ... -
Microbial Community Structure Alogn a Horizontal Oxygen Gradient in a Costa Rican Volcanic Influeced Acid Rock Drainage System
(2020-06-22)We describe the geochemistry and microbial diversity of a pristine environment that resembles an acid rock drainage (ARD) but it is actually the result of hydrothermal and volcanic influences. We designate this environment, ... -
Microwave assisted synthesis: A Mn/Ni reaction system affording Mn5Ni4, Mn2Ni2 and Mn7 complexes
(2013-11)Following our interest in microwave assisted synthesis in coordination chemistry; we report here the results of the study of a mixed metal Mn/Ni system under common bench-top conditions and using the microwave reactor. ... -
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 ... -
Monomeric Germanium(II) Amides Bearing β-Diketiminato Ligands: Synthesis, Structural Characterization, and Thermal Properties
(2014-09)Germanium(II) compounds featuring β-diketiminate-type ligands are attractive for applications as nanoparticle precursors, imaging agents, and components of electronic devices. In this work, we report the synthesis of ... -
Neutral organic redox pairs based on sterically hindered hydroquinone/benzoquinone derivatives for dye-sensitized solar cells
(2018-06)Substituted derivatives of hydroquinone/benzoquinone were studied as organic redox mediators in the electrolyte for dye-sensitized solar cells (DSSCs). Thus, di-tert-butylhydroquinone (DTHQ), thymohydroquinone (ThymHQ) and ... -
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). ... -
Optimization of semiochemical-based trapping of Metamasius hemipterus sericeus (Olivier) (Coleoptera: Curculionidae)
(1996-08)Response of adults of the West Indian sugarcane weevil,Metamasius hemipterus sericeus, to various semiochemical treatments and physical trap designs was studied in southern Florida in field-grown banana and Canary Island ... -
Oral administration of Costa Rican guava (Psidium friedrichsthalianum) juice induces changes in urinary excretion of energy-related compounds in Wistar rats determined by 1H NMR
(2020-08)Introduction: Psidium friedrichsthalianum fruits have in vitro antioxidant activity and their intake has been suggested to have potential health benefits; however, there is still no evidence on the potential in vivo effect ... -
Organic Acids without a Carboxylic Acid Functional Group
(Journal of Chemical Education 77(7):910-915. July 2000, 2000-07)This paper presents several organic molecules that have been labeled as acids but do not contain a carboxylic acid functional group. The rationale for the nomenclature and appropriate explanations for the apparent acidity ... -
Pheromone chirality of african palm weevil, Rhynchophorus phoenicis (F.) and palmetto weevil, Rhynthophorus crueniatus (F.) (Coleoptera: Curculionidae)
(1994-09)There are four stereoisomers of both 3-methyl-octan-4-ol, the aggregation pheromone of the African palm weevil,Rhynchophorus phoenicis (F.) and 5-methyl-octan-4-ol, the aggregation pheromone of the palmetto weevil,Rhynchophorus ... -
Pheromone chirality of asian palm weevils,Rhynchophorus ferrugineus (Oliv.) andR. vulneratus (Panz.) (Coleoptera: Curculionidae)
(1996-02)Production of 4-methyl-5-nonanol, and 4-methyl-5-nonanone by two sympatric Asian palm weevils,Rhynchophorus ferrugineus (Oliv.) andR. vulneratus (Panz.) suggested that enantiospecificity of either compound could impart ...