Química
Envíos recientes
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Effect on cell growth, viability and migration of geraniol and geraniol-containing essential oil from Lippia alba (Verbenaceae) on gastric carcinoma cells
(2021)Natural products used to treat cancer, or as leads for the development of preventive and co-adjuvant treatment strategies, are still a current approach. We studied the effect of essential oils from the medicinal plant ... -
Determination of the process variables for adsorption and desorption of phosphate from wastewater by selective ion exchangers on magnetic particles
(2015-08-04)In this study different process variables were evaluated for the adsorption and desorption of phosphate from wastewater by using selective ion exchangers with magnetic particles modi-fied with layered double hydroxides ... -
Phosphate recovery from wastewater with magnetic particles and enrichment of the reclaimed solution as a source for struvite precipitation
(2016-05-30)In this study phosphate was recovered from different wastewaters (WW) by using magnetic particles modified with layered double hydroxides (LDH). Afterwards, the enriched reclaimed solution was used for the precipitation ... -
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 ... -
Implementación de un sistema de evaluación de riesgo en una industria farmacéutica aplicando la herramienta fmea (failure mode effect and analysis) como instrumento para determinar los atributos de calidad en la evaluación de procesos
(2021-09-09)En el 2019, se desarrolla la implementación de una metodología de evaluación de riesgos aplicada a procesos farmacéuticos, con la finalidad de detectar fallas y puntos de mejora. Inicialmente, se realiza un entrenamiento ... -
Análisis fisicoquímico no invasivo de colgantes hachoides de piedras verdes de las colecciones arqueológicas del Museo Nacional de Costa Rica y del Museo del Jade y de la Cultura Precolombina
(2021-05)Las sociedades precolombinas de la actual Costa Rica formaron uno de los principales centros de producción de artefactos de jade y piedras verdes de Mesoamérica, los colgantes hachoides fabricados en el actual territorio ... -
Evolution of the reactive surface area of ferrihydrite: time, pH, and temperature dependency of growth by Ostwald ripening
(2019-02)Surface area is a crucial property of metal oxides for scaling ion adsorption phenomena. For ferrihydrite (Fh), the value is uncertain. Moreover, it rapidly changes with time, pH, and temperature. In this study, the dynamic ... -
Surface area of ferrihydrite consistently related to primary surface charge, ion pair formation, and specific ion adsorption
(2020-01-20)The specific surface area (SSA) of metal oxides is pivotal for scaling of surface phenomena. For ferrihydrite (Fh), the SSA can be assessed by probing the surface with ions that specifically adsorb (e.g. protons or phosphate). ... -
Ternary complex formation of phosphate with Ca and Mg ions binding to ferrihydrite: Experiments and mechanisms
(2020-03-25)Calcium (Ca) and magnesium (Mg) are the most abundant alkaline-earth metal ions in nature, and their interaction with ferrihydrite (Fh) affects the geochemical cycling of relevant ions, including phosphate (PO4). The ... -
Boron adsorption to ferrihydrite with implications for surface speciation in soils: Experiments and modeling
(2020-07-29)The adsorption and desorption of boric acid onto reactive materials such as metal (hydr)oxides and natural organic matter are generally considered to be controlling processes for the leaching and bioavailability of boron ... -
High and low affinity sites of ferrihydrite for metal ion adsorption: Data and modeling of the alkaline-earth ions Be, Mg, Ca, Sr, Ba, and Ra
(2020-10-01)The alkaline-earth metal ion series comprises Be, Mg, Ca, Sr, Ba, and Ra. Calcium (Ca) and magnesium (Mg) are the most abundant alkaline-earth metal ions in nature and their interaction with the mineral surfaces of metal ... -
Carbonate adsorption to ferrihydrite: Competitive interaction with phosphate for use in soil systems
(2018-12)Carbonate (CO3) interacts with Fe-(hydr)oxide nanoparticles, affecting the availability and geochemical cycle of other important oxyanions in nature. Here, we studied the carbonate–phosphate interaction in closed systems ... -
Assessing the reactive surface area of soils and the association of soil organic carbon with natural oxide nanoparticles using ferrihydrite as proxy
(2020-09-09)Assessment of the surface reactivity of natural metal-(hydr)oxide nanoparticles is necessary for predicting ion adsorption phenomena in soils using surface complexation modeling. Here, we describe how the equilibrium ... -
Chemical composition of essential oils of the tree Melaleuca quinquenervia (Myrtaceae) cultivated in Costa Rica
(2021-04-21)Introduction: Melaleuca is a Myrtaceous genus of flowering plants of about 290 species, distributed throughout Indonesia, Papua New Guinea, Australia, and New Caledonia. Objective: To identify the chemical composition of ... -
Rapid shift in microbial community structure in a neutral hydrothermal hot spring from Costa Rica
(2020)In this work, we characterize the geochemistry and microbial community of Bajo las Peñas, a neutral (pH 6.5-7.4), hot spring (T = 62.0-68.0°C) located near Turrialba Volcano, Costa Rica. The microbiota at its two sources ... -
Bocaparvovirus, Erythroparvovirus and Tetraparvovirus in New World Primates from Central America
(2020)Parvoviruses in the genera Bocaparvovirus (HBoV), Erythroparvovirus (B19) and Tetraparvovirus (PARV4) are the only autonomous parvoviruses known to be associated with human and non‐human primates based on studies and ... -
ArsH protects Pseudomonas putida from oxidative damage caused by exposure to arsenic
(2020-03-23)The two As resistance arsRBC operons of Pseudomonas putida KT2440 are followed by a downstream gene called arsH that encodes an NADPH‐dependent flavin mononucleotide reductase. In this work, we show that the arsH1 and (to ... -
The putative phosphate transporter PitB (PP1373) is involved in tellurite uptake in Pseudomonas putida KT2440
(2020)Tellurium oxyanions are chemical species of great toxicity and their presence in the environment has increased because of mining industries and photovoltaic and electronic waste. Recovery strategies for this metalloid that ... -
Using Student Profiles to Motivate and Understand How to Attract Women to Computer Science
(2020)This article reports how to build and analyze student profiles to influence the perception that girls and young women have of the profession, and of the diverse work opportunities that exist in Computer Science in Costa ... -
General Chemistry Without Orbitals
(2020)We illustrate the solutions of Schroedinger's equation for the hydrogen atom in coordinates of all four systems, and differentiate the applicability of orbitals in these four systems. We present reasons that future textbooks ...
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