59 results on '"Inorganic chemistry"'
Search Results
2. Revista CENIC Ciencias Químicas
- Subjects
analytical chemistry ,physical chemistry ,inorganic chemistry ,organic chemistry ,Chemistry ,QD1-999 ,Science - Published
- 2021
3. Diazo compounds and palladium–aryl complexes: trapping the elusive carbene migratory insertion organometallic products
- Author
-
Ana Albeniz and Francisco Villalba
- Subjects
Inorganic Chemistry ,Chemistry - Abstract
The reactions of Pd–aryl complexes with diazo compounds N2CH–CH=CHPh and N2CHPh allowed us to isolate the organo- metallic products formed right after the migratory insertion of a non-stabilized CHR carbene into the Pd–aryl bond. η3-Allylic and η3-benzylic palladium complexes were formed respectively. This is compelling experimental evidence for the key step in the palla- dium-catalyzed cascade transformations of diazo derivatives leading to multiple C–C or C–X bond formation., MICINN (AEI, grant PID2019-111406GB-I00), Junta de Castilla y León-FEDER (grant VA224P20), MEC (FPU-17/04559 fellowship to F. V.)
- Published
- 2022
4. Molecular management of high-grade serous ovarian carcinoma
- Author
-
Paula Punzón-Jiménez, Victor Lago, Santiago Domingo, Carlos Simón, Aymara Mas, UCH. Departamento de Medicina y Cirugía, and Producción Científica UCH 2022
- Subjects
Ovarian Neoplasms ,Ovaries - Biopsy ,Organic Chemistry ,General Medicine ,Carcinoma, Ovarian Epithelial ,Catalysis ,Tumor markers ,Computer Science Applications ,Marcadores tumorales ,Inorganic Chemistry ,Ovaries - Cancer - Diagnosis ,Humans ,Female ,Physical and Theoretical Chemistry ,Ovarios - Biopsia ,Molecular Biology ,Spectroscopy ,Ovarios - Cáncer - Diagnóstico - Abstract
Este artículo se encuentra disponible en la siguiente URL: https://www.mdpi.com/1422-0067/23/22/13777 Este artículo de investigación pertenece al número especial "Molecular Advances in Cancer Genetics 2.0". High-grade serous ovarian carcinoma (HGSOC) represents the most common form of epithelial ovarian carcinoma. The absence of specific symptoms leads to late-stage diagnosis, making HGSOC one of the gynecological cancers with the worst prognosis. The cellular origin of HGSOC and the role of reproductive hormones, genetic traits (such as alterations in P53 and DNA-repair mechanisms), chromosomal instability, or dysregulation of crucial signaling pathways have been considered when evaluating prognosis and response to therapy in HGSOC patients. However, the detection of HGSOC is still based on traditional methods such as carbohydrate antigen 125 (CA125) detection and ultrasound, and the combined use of these methods has yet to support significant reductions in overall mortality rates. The current paradigm for HGSOC management has moved towards early diagnosis via the non-invasive detection of molecular markers through liquid biopsies. This review presents an integrated view of the relevant cellular and molecular aspects involved in the etiopathogenesis of HGSOC and brings together studies that consider new horizons for the possible early detection of this gynecological cancer.
- Published
- 2022
5. Liver steatosis and steatohepatitis alter bile acid receptors in brain and induce neuroinflammation a contribution of circulating bile acids and blood-brain barrier
- Author
-
Noemi Fiaschini, Mariateresa Mancuso, Mirella Tanori, Eleonora Colantoni, Roberta Vitali, Gianfranco Diretto, Laura Lorenzo Rebenaque, Laura Stronati, Anna Negroni, Producción Científica UCH 2022, and UCH. Departamento de Producción y Sanidad Animal, Salud Pública Veterinaria y Ciencia y Tecnología de los Alimentos
- Subjects
Bile acids - Receptors ,Ácidos biliares - Receptores ,Catalysis ,Inorganic Chemistry ,Bile Acids and Salts ,Mice ,Intestines - Inflammation ,Non-alcoholic Fatty Liver Disease ,Occludin ,Liver ,Animals ,Physical and Theoretical Chemistry ,high-fat diet ,intestinal inflammation ,liver ,brain inflammation ,bile acid receptors ,bile acids ,blood brain barrier ,Molecular Biology ,Spectroscopy ,Encefalitis ,Hígado ,Organic Chemistry ,Endothelial Cells ,Brain ,General Medicine ,Computer Science Applications ,Blood-Brain Barrier ,Intestinos - Inflamación ,Neuroinflammatory Diseases ,Encephalitis - Abstract
Este artículo se encuentra disponible en la siguiente URL: https://www.mdpi.com/1422-0067/23/22/14254 En este artículo de investigación también participan: Laura Stronati y Anna Negroni. Este artículo de investigación pertenece al número especial "State-of-the-Art Molecular Neurobiology in Italy". A tight relationship between gut-liver diseases and brain functions has recently emerged. Bile acid (BA) receptors, bacterial-derived molecules and the blood-brain barrier (BBB) play key roles in this association. This study was aimed to evaluate how non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) impact the BA receptors Farnesoid X receptor (FXR) and Takeda G-protein coupled receptor 5 (TGR5) expression in the brain and to correlate these effects with circulating BAs composition, BBB integrity and neuroinflammation. A mouse model of NAFLD was set up by a high-fat and sugar diet, and NASH was induced with the supplementation of dextran-sulfate-sodium (DSS) in drinking water. FXR, TGR5 and ionized calcium-binding adaptor molecule 1 (Iba-1) expression in the brain was detected by immunohistochemistry, while Zonula occludens (ZO)-1, Occludin and Plasmalemmal Vesicle Associated Protein-1 (PV-1) were analyzed by immunofluorescence. Biochemical analyses investigated serum BA composition, lipopolysaccharidebinding protein (LBP) and S100 protein (S100 ) levels. Results showed a down-regulation of FXR in NASH and an up-regulation of TGR5 and Iba-1 in the cortex and hippocampus in both treated groups as compared to the control group. The BA composition was altered in the serum of both treated groups, and LBP and S100 were significantly augmented in NASH. ZO-1 and Occludin were attenuated in the brain capillary endothelial cells of both treated groups versus the control group. We demonstrated that NAFLD and NASH provoke different grades of brain dysfunction, which are characterized by the altered expression of BA receptors, FXR and TGR5, and activation of microglia. These effects are somewhat promoted by a modification of circulating BAs composition and by an increase in LBP that concur to damage BBB, thus favoring neuroinflammation.
- Published
- 2022
6. Ligandos metálicos trispiridilo de aluminio, antimonio y bismuto: efecto del átomo puente en su reactividad y ensamblaje supramolecular
- Author
-
García Romero, Álvaro, Álvarez González, Celedonio Manuel, García Rodríguez, Raúl, and Universidad de Valladolid. Escuela de Doctorado
- Subjects
Inorganic Chemistry ,Organometálica ,Química inórganica ,Supramolecular ,Síntesis Química ,Supramolecular chemistry ,2303 Química Inorgánica ,Organometallic - Abstract
The work collected in this PhD thesis encompasses the synthesis, characterization, coordination chemistry, and reactivity of a series of trispyridyl compounds of metallic main-group elements of groups 13 and 15, concretely, aluminium, antimony and bismuth, and their use as building blocks in supramolecular chemistry. The results of this work have been divided into three chapters: Chapter I describes (i) a post-functionalization strategy for tris(2-pyridyl) aluminates via their reaction with alcohols, which allows the introduction of chirality into the aluminate and access to supramolecular chemistry by introducing functionalities in the form of alkoxy groups, and (ii) the synthesis of the first anionic derivative of the tris(3-pyridyl) family of compounds and its unusual stability due to the absence of cooperativity between the aluminium and lithium metal centers. Chapter II reports (i) the modulation of the anion- and cation-coordinating ability of a family of tris(2-pyridyl)bismuthines through the introduction of substituents on the pyridinic rings, as well as their non-innocent reactivity, and (ii) the synthesis of tris(3-pyridyl) ligands of antimony and bismuth and the directing effect of the bridgehead atom in the construction of supramolecular structures by ligand coordination to metal centers. Finally, Chapter III presents the formation of supramolecular capsules based on the coordination of the tris(3-pyridyl) ligands of antimony and bismuth to metalloporphyrins. The different geometric profiles of the ligands, as well as the oxidation of the bridgehead atom, can be used to modulate the dimensions, morphology and dynamic behavior of the capsules., El trabajo recogido en esta tesis doctoral engloba la síntesis, estudio de propiedades, química de coordinación, reactividad y uso como bloques de construcción en química supramolecular de una serie de compuestos trispiridilo de elementos metálicos representativos de los grupos 13 y 15, concretamente, de aluminio, antimonio y bismuto. Los resultados de este trabajo se han dividido en tres capítulos: En el Capítulo I se describe: i) la estrategia de postfuncionalización de tris(2-piridil) aluminatos mediante su reacción con alcoholes, lo que permite la introducción de quiralidad en el aluminato y el acceso a química supramolecular al introducir funcionalidades en forma de grupos alcoxi; ii) la síntesis del primer derivado aniónico de la familia de compuestos tris(3-piridilo), y su inusual estabilidad debido a la ausencia de cooperatividad entre los centros metálicos de aluminio y litio. En el Capítulo II se estudia: i) la modulación de la capacidad para coordinar aniones y cationes de una familia de tris(2-piridil)bismutinas a través de la introducción de sustituyentes en los anillos piridínicos, así como su reactividad no inocente; ii) la síntesis de los ligandos tris(3-piridilo) de antimonio y bismuto y el efecto director del átomo puente en la construcción de estructuras supramoleculares por coordinación del ligando a centros metálicos. Finalmente, en el Capítulo III se muestra la formación de cápsulas supramoleculares basadas en la coordinación a metaloporfirinas de los ligandos tris(3-piridilo) de antimonio y bismuto. El distinto perfil geométrico de los ligandos, así como la oxidación del átomo puede pueden utilizarse para modular las dimensiones, la morfología y el comportamiento dinámico de las cápsulas., Escuela de Doctorado, Doctorado en Química: Química de Síntesis, Catálisis y Materiales Avanzados
- Published
- 2022
7. Gerenciamento dos resíduos da disciplina química inorgânica II do curso de química da Universidade Federal do Rio Grande do Sul Management of residues of an undergraduate inorganic chemistry course at the Federal University of Rio Grande do Su
- Author
-
Annelise Engel Gerbase, José Ribeiro Gregório, and Tatiana Calvete
- Subjects
chemical waste management ,environment ,inorganic chemistry ,Chemistry ,QD1-999 - Abstract
Beginning students in chemistry usually do not realize that wastes generated in their experimental classes constitute an environmental problem and that residues must be treated or disposed of in a suitable way. In this manuscript we describe the work that we have been doing in the inorganic chemistry course of the Federal University of Rio Grande do Sul with the objective of creating a critical consciousness in the students about the chemical wastes they generate. With this policy, students are required to take into account the nature of the residues they generate, how they can treat or segregate them, and how they can keep them in a suitable way for final destination, instead of simply throwing them away.
- Published
- 2006
- Full Text
- View/download PDF
8. Aluminium-Cobalt-Pillared Clays (Al-Co-PILCs) as catalysts for dye degradation using HCO3-/H2O2 system
- Author
-
Macías Quiroga, Iván Fernando, Sanabria González, Nancy Rocío, and Procesos Químicos Cataliticos y Biotecnológicos
- Subjects
Química experimental ,Costos ,Azo dyes ,Advanced oxidation processes ,Experimental chemistry ,Química mineral ,Arcillas pilarizadas ,Bicarbonate-activated hydrogen peroxide system ,Costs ,540 - Química y ciencias afines ,Peróxido de hidrógeno activado con bicarbonato ,Cinética ,Kinetics ,Procesos avanzados de oxidación ,Pillared clays ,Colorantes azoicos ,Inorganic chemistry - Abstract
fotografías, gráficos, tablas, En la presente investigación se realizó la caracterización química, estructural y textural de una bentonita proveniente del norte del departamento de Tolima. El mineral arcilloso fue sometido a un proceso de pilarización con aluminio y posterior impregnación con cobalto y el material obtenido - Co(%)/Al-PILC - fue utilizado como catalizador en la activación del peróxido de hidrógeno con bicarbonato (sistema BAP, por sus siglas en inglés Bicarbonate-Activated Peroxide) para la oxidación de dos colorantes alimenticios. Los materiales Co(1.0, 3.0 y 6.0%)/Al-PILC mostraron una alta actividad para la decoloración del ponceau 4R (P4R) y amarillo sunset (AS) en solución acuosa, sin embargo, la arcilla impregnada con 1.0% de cobalto fue la que preservó en mayor proporción las propiedades texturales del soporte Al-PILC. Se utilizó la metodología de superficie de respuesta (MSR) basada en un diseño central compuesto (DCC) para analizar el efecto de las variables H2O2, NaHCO3 y Co(1.0%)/Al-PILC sobre la oxidación de los colorantes P4R y AS, considerando como variables de respuesta la decoloración y la remoción de carbono total (CT). Los diseños experimentales mostraron que las concentraciones de peróxido de hidrógeno y bicarbonato son las variables que más influyen en la decoloración y mineralización de los dos colorantes alimenticios estudiados. Se obtuvieron dos modelos cinéticos empíricos de segundo orden para cada colorante, uno para la decoloración y otro para la remoción de carbono total. También se determinaron las condiciones óptimas de las variables de respuesta para el P4R y AS, y bajo estas condiciones se evaluó la estabilidad del catalizador (ciclos de reuso) y el efecto de los “scavengers” de radicales. Bajo las condiciones de reacción, determinadas por la optimización multiobjetivo de los modelos, se realizaron las pruebas cinéticas de decoloración, mostrando que los datos experimentales de concentración normalizada para el P4R y AS se ajustaron a ecuaciones cinéticas de pseudo segundo y primer orden, respectivamente. También se estableció, a través de pruebas de toxicidad por digestión anaerobia, que los subproductos de la oxidación de los colorantes no son tóxicos. Finalmente, con los modelos empíricos y cinéticos de decoloración, se realizaron simulaciones para realizar la evaluación preliminar de costos de tratamiento, estudiando el efecto de la concentración y volumen de agua a tratar. (Texto tomado de la fuente) In the present investigation, the chemical, structural and textural characterization of a bentonite from the northern department of Tolima (Colombia) was carried out. The clay mineral was subjected to a process of pillarization with aluminum and subsequent impregnation with cobalt. The materials obtained - Co(%)/Al-PILCs - were used as a catalyst for the activation of hydrogen peroxide with bicarbonate (BAP system) in the oxidation of two food dyes. The Co(1.0, 3.0 and 6.0%)/Al-PILC materials showed high activity for the decolorization of ponceau 4R (P4R) and sunset yellow (AS) in aqueous solution. However, the clay impregnated with 1.0% cobalt preserved the textural properties of the Al-PILC support. Response surface methodology (RSM) based on a central composite design (CCD) was used to analyze the effect of H2O2, NaHCO3 and Co(1.0%)/Al-PILC as variables on the oxidation of P4R and AS dyes. Discoloration and total carbon (TC) removal were considered as response variables. The experimental designs showed that hydrogen peroxide and bicarbonate concentrations are the variables that influence most the decolorization and mineralization for both food dyes studied. Two second-order empirical models were obtained for each dye, one for decolorization and the other for total carbon removal. Optimal conditions were determined for response variables of P4R and AS. Therefore, under the mentioned conditions, the stability of the catalyst (reuse cycles) and the effect of free radical scavengers were evaluated. Under the reaction conditions determined by multi-objective optimization, decolorization kinetic tests were performed, showing that the experimental data of normalized concentration for P4R and AS fitted the pseudo second and first order kinetic models, respectively. It was also established through toxicity tests by anaerobic digestion that the by-products of dye oxidation are non-toxic. Finally, with the empirical and kinetic decolorization equations, modeling was carried out for the preliminary evaluation of treatment costs, studying the effect of the concentration and volume of water to be treated. Doctorado Doctor en Ingeniería – Ingeniería Química Química Y Procesos
- Published
- 2021
9. Revista Colombiana de Química
- Subjects
organic chemistry ,biochemistry ,applied chemistry ,analytical chemistry ,physical chemistry ,inorganic chemistry ,Chemistry ,QD1-999 - Published
- 2013
10. Actualización de las guias de laboratorio de la facultad de ingeniería ambiental de la Universidad santo tomás de Villavicencio aplicando conceptos de quimica verde y trabajo en la microescala
- Author
-
Buitrago Barbosa, Camila Alejandra, Velásquez Cuestas, Jairo Andrés, and Martínez Molina, Saúl
- Subjects
Residuos Solidos ,Organic Chemistry ,Quimica Organica ,Gestión ambiental ,Solid Waste Management ,Tesis y disertaciones académicas ,Inorganic Chemistry ,trabajo en la microescala ,Impacto Ambiental ,Laboratorios ,Environmental Impact ,prueba de validación ,quimica verde ,Sustentabilidad ,Quimica Inorganica ,laboratorios universitarios - Abstract
El trabajo ejecutado proviene del Macro proyecto interinstitucional “Estudio para la gestión de residuos generados en los laboratorios de la Facultad de Ingeniería Ambiental de la Universidad Santo Tomás sede Villavicencio” realizado entre la Facultad de Ingeniería Ambiental de la Universidad Santo Tomás sede Villavicencio y la Universidad Tecnológica Federal do Paraná. (Mosquera, Barbosa, Montañez, & Murcia, 2019). Este documento representa la segunda fase del Macroproyecto y su objetivo es establecer medidas de manejo, enfocado en el establecimiento de propuestas de mejora en las guías de laboratorio priorizadas, con base en la evaluación de peligrosidad de los reactivos usados en estas, la realización de pruebas de validación para las propuestas de mejora en las guías de laboratorio priorizadas y finalmente, la estimación de la generación de residuos peligrosos mediante análisis estequiométrico. La ejecución del proyecto estandarizó un límite de guías a partir del material de trabajo concluido en la primera fase. El total de guías de análisis fueron diez, según ranking de peligrosidad, subdivididas por dos grupos, con base a los peligros y las categorías de peligros establecidas en el Sistema Globalmente Armonizado. . Con el apoyo del tercer principio de la química verde y a partir de la prueba de validación se logró eliminar reactivos tóxicos y ecotóxicos. Como resultado se tiene una actualización de las guías de laboratorio, reduciendo cerca del 24% de los 320 peligros que originalmente se encontraban en las guías sin modificar; la disminución de uso de reactivos en estado líquido o sólido se encuentra entre un 50% y 80 % por procedimientos y al comparar el uso de sustancias en la guías originales con la guías propuestas es de un 27%. The work carried out comes from the Macro inter-institutional project "Study for the management of waste generated in the laboratories of the Faculty of Environmental Engineering of the Universidad Santo Tomás Villavicencio headquarters" carried out between the Faculty of Environmental Engineering of the Universidad Santo Tomás Villavicencio and the Universidad Tecnologica Federal do Paraná (Mosquera , Barbosa , Montañez , & Murcia , 2019). This document represents the second phase of the Macroproject and its objective is to establish management measures, focused on the establishment of proposals for improvement in the prioritized laboratory guides, based on the evaluation of the dangerousness of the reagents used in these, the performance of tests of validation for the improvement proposals in the prioritized laboratory guides and finally, the estimation of the generation of hazardous waste according to the prioritized laboratory guides through stoichiometric analysis The execution of the project standardized a limit of guides based on the work material completed in the first phase. The total number of analysis guides were ten, according to the hazard ranking, subdivided into two groups, based on the hazards and the hazard categories established in the Globally Harmonized System. Based on the prioritizations, those highly dangerous reagents or activities that affect health and the environment are synthesized, substituted or reduced. With the support of the third principle of green chemistry and from the validation test, it was possible to eliminate toxic and ecotoxic,reagents. As a result, the laboratory guides are updated, reducing about 24% of the 320 hazards that were originally in the unmodified guides.; the decrease in the use of reagents in liquid or solid state is between 50% and 80% when comparing the use of substances in the original guidelines with the proposed guidelines, it is 27%.. Ingeniero Ambiental http://www.ustavillavicencio.edu.co/home/index.php/unidades/extension-y-proyeccion/investigacion Pregrado
- Published
- 2020
11. Estudio conformacional de los ligandos macrocíclicos 1,4,8,11-tetraoxaciclotetradecano y 1,4,8,11-tetratiaciclotetradecano y de sus complejos con cualquier metal
- Author
-
Raja Avilés, Paula del Carmen, García González, Luis, Serrano Martínez, José Luis, and Ingeniería Química y Ambiental
- Subjects
Química Inorgánica ,Metals ,Metales ,2303 Química Inorgánica ,Inorganic chemistry - Abstract
El presente Trabajo Final de Grado se basa en otros llevadosa cabo en el Área de Química Inorgánica en los que se estudiaba el estudio conformacional de complejos de 1,4,8,12-tetraazaciclopentadecano, 1,4-dioxa-8,12-diazaciclopentadecano y 1,4,8,11-tetraazaciclotetradecano. De este último macrociclo se realizaron en 2016 y 2017 tres TFG similares al que vamos a llevar a cabo, divididos en: i) estudio del macrociclo libre y complejado con metales del grupo 10; ii) macrociclo complejado con metales de la primera serie de transición y iii) macrociclo complejado con metales de la segunda y tercera serie de transición. Al final de este Capítulo resumimos los aspectos más interesantes del TFG en el que se aborda el estudio de los complejos formados por metales de la primera serie de transición, ya que nos permite, de un vistazo, comprender cómo es la arquitectura de este nuevo TFG. El germen de todos estos Proyectos comienza con la publicación por miembros del Área de Química Inorgánica de la UPCT de un artículo titulado Coordination to metal center: A tool to fix high energy conformations in organic molecules. Application to 2,4,4- trimethyl-1,5,9-triazacyclododec-1-ene and related macrocycles, [Pérez et al., 2011], basado en estudios realizados en cooperación con la profesora Mª Dolores Santana, del Departamento de Química Inorgánica de la Universidad de Murcia, Gotzone Barandika de la Facultad de Farmacia en Vitoria-Gasteiz y A. Calderón-Casado, de la Facultad de Ciencia y Tecnología en Bilbao. Los antecedentes en la investigación quedan reflejados en la introducción del citado artículo, que resumimos a continuación, y en el libro titulado The Chemistry of Macrocyclic Ligand Complexes [Lindoy, 1989]. Escuela Técnica Superior de Ingeniería Industrial Universidad Politécnica de Cartagena
- Published
- 2020
12. Síntesis, caracterización estructural y aplicaciones de nuevos imidato-complejos de paladio(II) con ligandos quelato N^N-dadores
- Author
-
Torregrosa Gomis, Enrique, Serrano Martínez, José Luis, García González, Luis, and Ingeniería Química y Ambiental
- Subjects
Química Inorgánica ,3303.11 Química Industrial ,Química orgánica ,Organic chemistry ,Análisis químico ,Chemical analysis ,2303 Química Inorgánica ,Inorganic chemistry ,3303.03 Procesos Químicos - Abstract
Los objetivos de este TFE son: I. Revisión bibliográfica sobre complejos de paladio con ligandos quelato N^N-dadores convencionales (2,2´-bipiridina, N,N,N´, N´-tetrametiletilendiamina, bis(pirazolil)metano) y otros promotores de la solubilidad en agua, como las -diiminas sulfonatadas. II. Preparación de ligandos del tipo bis(pirazolil)metano y -diiminas sulfonatadas para su uso como ligandos en Química de Coordinación. III. Preparación de precursores metálicos como Pd2(dba)3. IV. Preparación de nuevos complejos Imidato por distintas rutas sintéticas como la adición oxidativa de N-Bromosuccinimida o reacciones ácido base a partir de Acetato de paladio V. Caracterización por técnicas analíticas y espectroscopía IR, RMN 1H, y RMN 31P de los ligandos y complejos aislados. (disponibles en la U.P.C.T. y en la U.M.) VI. Estudio estructural, por difracción de rayos X de monocristal, de algunos de los complejos preparados. Escuela Técnica Superior de Ingeniería Industrial Universidad Politécnica de Cartagena
- Published
- 2020
13. El juego en el aprendizaje significativo de la química inorgánica en los estudiantes del Bachillerato de la U.E. 'San Joaquín'
- Author
-
García Prado, Mayra de la Nube and Rodríguez Rensoli, Madelin
- Subjects
Meaningful learning ,Aprendizaje significativo ,Aprendizaje basado en el juego ,Estrategia metodológica ,Química inorgánica ,Inorganic chemistry - Abstract
La presente investigación, tiene como objetivo demostrar la influencia de la estrategia metodológica basada en el juego en el desarrollo del aprendizaje significativo de la química inorgánica binaria en los estudiantes del Primero de Bachillerato de la U.E. ‘‘San Joaquín’’, sustentado en las problemáticas que se han detectado en este tema, y en el enfoque constructivista que se asume en el currículo escolar actual. Se asumió un tipo de estudio cualitativo, con énfasis en la investigación – acción, y se utilizaron métodos que favorecieron obtener los resultados esperados. La investigación se desarrolló desde las fases de diagnóstico, diseño, implementación, evaluación e interpretación de resultados, que permitieron desde la reflexión – acción, ir perfeccionando la propuesta. La aplicación de la química inorgánica binaria en la vida diaria constituyó el elemento fundamental de los resultados; se diseñó y aplicó la estrategia metodológica basada en el juego durante la enseñanza-aprendizaje, teniendo en cuenta el trabajo en grupos, para favorecer un aprendizaje significativo. A partir de los resultados obtenidos se pudo concluir que la estrategia metodológica del juego aporta significativamente al desarrollo del aprendizaje de los estudiantes, lo que conlleva a cumplir el perfil de salida en este nivel de educación. The present research aims to demonstrate the influence of the game-based methodological strategy in the development of significant learning of binary inorganic chemistry in the students of Primero de Bachillerato of the U.E. ‘‘ San Joaquín ’’, based on the problems that have been detected in this matter and in the constructivist approach that is assumed in the current school curriculum. A type of qualitative study was assumed, with an emphasis on action research, and methods that favored obtaining the expected results were used. The research was developed from the diagnosis, design, implementation, evaluation and interpretation of results, which allowed from reflection – action to perfect the proposal. The application of binary inorganic chemistry in daily life was the fundamental element of the results; the game-based methodological strategy was designed and applied during teaching-learning, taking into account group work, to promote meaningful learning. From the results obtained, it was concluded that the methodological strategy of the game contributes significantly to the development of student learning, which leads to meeting the exit profile at this level of education. Azogues Especialista en Pedagogía para profesores de Bachillerato Técnico
- Published
- 2020
14. The role of electron transfer in the fragmentation of phenyl and cyclohexyl boronic acids
- Author
-
Marta Łabuda, Pedro M. P. Gois, João Pereira-da-Silva, Beatriz Pamplona, T. Kilich, Paulo Limão-Vieira, Gustavo García, M. Mendes, F. Ferreira da Silva, A. I. Lozano, Ministerio de Economía y Competitividad (España), and Fundação para a Ciência e a Tecnologia (Portugal)
- Subjects
Anions ,Models, Molecular ,Boronic acids ,Molecular Conformation ,Electrons ,010402 general chemistry ,Photochemistry ,7. Clean energy ,01 natural sciences ,Catalysis ,Dissociation (chemistry) ,Article ,law.invention ,Negative ion formation ,Inorganic Chemistry ,Crossed molecular beam ,Electron Transport ,lcsh:Chemistry ,Electron transfer ,chemistry.chemical_compound ,Fragmentation (mass spectrometry) ,Reflectron ,law ,Cyclohexanes ,Molecular orbital ,Physical and Theoretical Chemistry ,Phenylboronic acid ,Molecular Biology ,lcsh:QH301-705.5 ,Spectroscopy ,TOF mass spectrometry ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,General Medicine ,3. Good health ,0104 chemical sciences ,Computer Science Applications ,lcsh:Biology (General) ,lcsh:QD1-999 ,Potassium ,Thermodynamics ,Boronic acid - Abstract
In this study, novel measurements of negative ion formation in neutral potassium-neutral boronic acid collisions are reported in electron transfer experiments. The fragmentation pattern of phenylboronic acid is comprehensively investigated for a wide range of collision energies, i.e., from 10 to 1000 eV in the laboratory frame, allowing some of the most relevant dissociation channels to be probed. These studies were performed in a crossed molecular beam set up using a potassium atom as an electron donor. The negative ions formed in the collision region were mass analysed with a reflectron time-of-flight mass spectrometer. In the unimolecular decomposition of the temporary negative ion, the two most relevant yields were assigned to BO&minus, and BO2&minus, Moreover, the collision-induced reaction was shown to be selective, i.e., at energies below 100 eV, it mostly formed BO&minus, while at energies above 100 eV, it mostly formed BO2&minus, In order to further our knowledge on the complex internal reaction mechanisms underlying the influence of the hybridization state of the boron atom, cyclohexylboronic acid was also investigated in the same collision energy range, where the main dissociation channel yielded BO2&minus, The experimental results for phenyl boronic acid are supported by ab initio theoretical calculations of the lowest unoccupied molecular orbitals (LUMOs) accessed in the collision process.
- Published
- 2019
15. Kinetics and influential factors of nanoscale iron-facilitated nitrate nitrogen removal
- Author
-
Shoufa Song and Yujia Song
- Subjects
lcsh:TD201-500 ,lcsh:Hydraulic engineering ,Chemistry ,Kinetics ,Inorganic chemistry ,Activation energy ,Reaction rate ,Adsorption ,Reaction rate constant ,lcsh:Water supply for domestic and industrial purposes ,lcsh:TC1-978 ,Mass transfer ,Nitrate nitrogen ,Nitrate nitrogen, water pollution, reaction kinetics, nanometer, adsorption ,Nanoscopic scale - Abstract
Song, Y. & Song, S. (March-April, 2017). Kinetics and influential factors of nanoscale iron-facilitated nitrate nitrogen removal. Water Technology and Sciences (in Spanish), 8(2), 93-103. In this paper, a new nanoscale iron adsorbent was prepared using the liquid phase reduction method. The effects of the initial nitrate nitrogen concentration, pH, and reaction temperature on the nitrate nitrogen removal efficiency of the nanoscale iron were investigated. The experimental results indicated that the initial nitrate nitrogen concentration significantly affected the reaction rate, but not the removal efficiency of the nanoscale iron. In addition, the optimal pH for the removal of nitrate nitrogen was 2.0. As the temperature increased, the nitrate nitrogen removal rate increased. A pseudo-second-order kinetic equation, in which the nitrate nitrogen concentration at reaction time t was used as the initial concentration, was developed in order to determine the reaction rate constant k at different temperatures. According to the results, the maximum value of k (0.014 mg/(L/min)) was observed at 50°C. The reaction activation energy Ea was approximately 17.18 kJ/mol. The reaction was primarily influenced by the mass transfer. In a neutral solution, in this case water, the reduction product of the nitrate nitrogen was ammonia nitrogen.
- Published
- 2017
16. Design and implementation of rubrics as an instrument for the evaluation of General and Inorganic Chemistry -course for engineering students
- Author
-
Pedronel Araque Marín, Sandra Adela Torijano Gutiérrez, and Nicolas Arango Londoño
- Subjects
Rúbrica ,Química General ,Química Inorgánica ,Química Geral ,Evaluación ,Ingeniería ,General Chemistry ,Engenharia ,Química Inorgânica ,Avaliação ,Inorganic Chemistry ,Teaching-learning ,Enseñanza-aprendizaje ,Engineering ,Rubric ,Ensino-aprendizagem ,General Earth and Planetary Sciences ,Rubrica ,Evaluation ,General Environmental Science - Abstract
Resumen La evaluación no puede limitarse a una prueba centrada en la repetición de contenidos que pretende valorar el grado de aprendizaje de los estudiantes, la evaluación debe brindar otro horizonte con relación a la calificación tradicional, es decir debe ser una herramienta válida para el proceso de enseñanza-aprendizaje. En el presente trabajo se propuso un diseño de rúbrica como instrumento de evaluación para la asignatura de Química General e Inorgánica de la Universidad EIA. La rúbrica basada en objetivos de aprendizaje, aspectos a valorar, descriptores, escala de calificación y criterios, fue implementada durante los periodo académico 2015-2 y 2016-1, la propuesta facilitó la calificación de desempeño de los estudiantes de primer semestre de ingeniería, no solo sobre lo que aprendieron, sino también de cómo aprendieron y las competencias desarrolladas en el proceso evidenciando diferencias estadísticamente significativa (p-valor < 0,05) en el número de estudiantes que aprobaron la asignatura. Abstract The assessment can not be limited to a test focused on the repetition of content that aims to assess the degree of student learning, assessment should provide another horizon in relation to the traditional rating, ie must be a valid tool for teaching-learning process. In this paper we design a proposal as an evaluation tool for the subject of General and Inorganic Chemistry of the University EIA. the rubric based on learning objectives, aspects to be evaluated, descriptors, criteria and rating scale, was implemented during the 2015-2 and 2016-1 academic year, the proposal facilitated the performance rating of freshmen engineering, not only about what they learned, but also how they learned and skills developed in the process demonstrating statistically significant difference (p-value
- Published
- 2019
17. Determinación de las propiedades de transporte de iones cobre y níquel en una membrana de intercambio catiónico
- Author
-
Leví Zuta and Alex Pilco
- Subjects
Aqueous solution ,Ion exchange ,Chemistry ,Inorganic chemistry ,transport number ,chemistry.chemical_element ,concentration polarization ,conductive membrane area ,área conductora de la membrana ,Copper ,Membrana de intercambio catiónico ,Nickel ,Membrane ,polarización por concentración ,Cation exchange membrane ,chronopotentiometry ,cronopotenciometría ,número de transporte ,General Earth and Planetary Sciences ,Nickel ions ,General Environmental Science - Abstract
El objetivo de este trabajo fue estudiar las propiedades de transporte de los iones cobre y níquel a través de una membrana de intercambio catiónico fumasep FKB-PK-130 utilizando cronopotenciometría. La fracción del área conductora de la membrana fue calculada en una solución acuosa de KCl a 0,025 M, obteniéndose un valor aproximado de 0,904, siendo dicho valor correspondiente a una membrana homogénea de intercambio iónico. Los números de transporte de los iones cobre y níquel en la membrana de intercambio catiónico fueron 0,966 y 0,923, respectivamente. The objective of this research was to study the transport properties of copper and nickel through the fumasep FKB-PK-130 cation exchange membrane using chronopotentiometry. The membrane’s conductive area was calculated in an aqueous solution of KCl 0.025 M, obtaining an value of 0.904, corresponding to a homogenous ion exchange membrane. The transport numbers of copper and nickel ions in the cation exchange membrane were measured as 0.966 and 0.923, respectively.
- Published
- 2018
18. Study of agglomeration and magnetic sedimentation of Glutathione@Fe3O4 nanoparticles in water medium
- Author
-
Edgar González and Wilfredo Marimón Bolívar
- Subjects
lcsh:TN1-997 ,magnetic nanoparticles ,Sedimentation (water treatment) ,Metal ions in aqueous solution ,Sodium ,Inorganic chemistry ,Magnetic separation ,magnetic sedimentation ,chemistry.chemical_element ,Nanoparticle ,02 engineering and technology ,Zinc ,010501 environmental sciences ,lcsh:Technology ,01 natural sciences ,Glutation ,lcsh:Mining engineering. Metallurgy ,cinética de agregación ,0105 earth and related environmental sciences ,lcsh:T ,Chemistry ,General Engineering ,Aqueous two-phase system ,sedimentación magnética ,021001 nanoscience & nanotechnology ,Glutathione ,nanopartículas magnéticas ,62 Ingeniería y operaciones afines / Engineering ,DLVO theory ,aggregation kinetics ,0210 nano-technology - Abstract
The study of the efficiency of the magnetic separation of nanoparticles in environment is important for its implementation in the remediation of water bodies. In this work the sedimentation dynamics of Glutathione@MNPs were evaluated for water systems with addition of calcium, zinc and sodium ions in a concentration range of 0-40 mg/L in the presence and absence of a vertical magnetic field of 0.2 T. Also, critical coagulation concentrations (CCC) were determined based on the DLVO theory. Particles stability in the absence of metal ions higher than 8 weeks could be observed, whereas in the presence of these ions the stability was reduced to 8 weeks. Separation of the material from the aqueous phase higher than 90% was obtained both for the presence of ions and for the material after the addition of heavy metals such as Hg and Cr. El estudio de la eficiencia de la separación magnética de nanopartículas del medio ambiente es importante para su implementación en la remediación de cuerpos de agua. En este trabajo se evaluó la dinámica de sedimentación de los Glutatión@MNPs en sistemas de agua con adición de iones de calcio, zinc y sodio en un rango de concentración de 0-40 mg/L en presencia y ausencia de un campo magnético vertical de 0,2 T. Las concentraciones críticas de coagulación (CCC) se determinaron basándose en la teoría de DLVO. Se observó estabilidad de la partícula en ausencia de iones metálicos mayores de 8 semanas, mientras que con la presencia de estos iones la estabilidad se redujo a 8 semanas. La separación del material de la fase acuosa superior al 90% se obtuvo tanto para la presencia de iones como para el material después de la adición de metales pesados tales como Hg y Cr.
- Published
- 2018
19. Systematic search for benzimidazole compounds and derivatives with antileishmanial effects
- Author
-
Francisco Hernández-Luis, Juan Carlos Sánchez-Salgado, Yareli Rojas-Aguirre, Pablo Bilbao-Ramos, José L. Medina-Franco, Francisco Bolás-Fernández, María Auxiliadora Dea-Ayuela, UCH. Departamento de Farmacia, and Producción Científica UCH 2018
- Subjects
0301 basic medicine ,Leishmaniasis - Farmacoterapia ,Benzimidazole ,Benzimidazoles - Therapeutic use ,030106 microbiology ,Antiprotozoal Agents ,Drug Evaluation, Preclinical ,Pharmacology ,Biology ,Catalysis ,Inorganic Chemistry ,Structure-Activity Relationship ,03 medical and health sciences ,chemistry.chemical_compound ,Informática - Aplicaciones en química ,Drug Discovery ,medicine ,Chemistry - Data processing ,Physical and Theoretical Chemistry ,Molecular Biology ,Leishmania ,Leishmaniasis - Tratamiento ,Drug discovery ,Bencimidazoles - Uso terapéutico ,Organic Chemistry ,Rational design ,Leishmaniasis ,General Medicine ,chEMBL ,medicine.disease ,030104 developmental biology ,Leishmaniasis - Treatment ,chemistry ,Cheminformatics ,Benzimidazoles ,Leishmaniasis - Chemotherapy ,Relevant information ,Information Systems ,Systematic search - Abstract
Este artículo se encuentra disponible en la página web de la revista en la siguiente URL: https://link.springer.com/article/10.1007%2Fs11030-018-9830-7 This is the peer reviewed version of the following article: Sánchez Salgado, JC., Bilbao Ramos, P., Dea Ayuela, MA., Hernández Luis, F., Bolás Fernández, F., Medina Franco, JL. & Rojas Aguirre, Y. (2018). Systematic search for benzimidazole compounds and derivatives with antileishmanial effects. Molecular Diversity, vol. 22, n. 4 (nov.), pp. 779-790, which has been published in final form at https://doi.org/10.1007/s11030-018-9830-7. Este es el post-print del siguiente artículo: Sánchez Salgado, JC., Bilbao Ramos, P., Dea Ayuela, MA., Hernández Luis, F., Bolás Fernández, F., Medina Franco, JL. & Rojas Aguirre, Y. (2018). Systematic search for benzimidazole compounds and derivatives with antileishmanial effects. Molecular Diversity, vol. 22, n. 4 (nov.), pp. 779-790, que se ha publicado de forma definitiva en https://doi.org/10.1007/s11030-018-9830-7. Leishmaniasis is a neglected tropical disease that currently affects 12 million people, and over 1 billion people are at risk of infection. Current chemotherapeutic approaches used to treat this disease are unsatisfactory, and the limitations of these drugs highlight the necessity to develop treatments with improved efficacy and safety. To inform the rational design and development of more efficient therapies, the present study reports a chemoinformatic approach using the ChEMBL database to retrieve benzimidazole as a target scaffold. Our analysis revealed that a limited number of studies had investigated the antileishmanial effects of benzimidazoles. Among this limited number, L. major was the species most commonly used to evaluate the antileishmanial effects of these compounds, whereas L. amazonensis and L. braziliensis were used least often in the reported studies. The antileishmanial activities of benzimidazole derivatives were notably variable, a fact that may depend on the substitution pattern of the scaffold. In addition, we investigated the effects of a benzimidazole derivative on promastigotes and amastigotes of L. infantum and L. amazonensis using a novel fluorometric method. Significant antileishmanial effects were observed on both species, with L. amazonensis being the most sensitive. To the best of our knowledge, this chemoinformatic analysis represents the first attempt to determine the relevance of benzimidazole scaffolds for antileishmanial drug discovery using the ChEMBL database. The present findings will provide relevant information for future structure–activity relationship studies and for the investigation of benzimidazole-derived drugs as potential treatments for leishmaniasis.
- Published
- 2018
20. Evaluation of the effect of the 2011 Tsunami on coastal forests by means of multiple isotopic analyses of tree-rings
- Author
-
Sayako Nakano, Mika Hayashi, Toshiro Yamanaka, Yoshihiro Nobori, Takeshi Nakatsuka, Masaki Sano, Maximo Larry Lopez Caceres, and Juan Pedro Ferrio
- Subjects
0106 biological sciences ,Soil salinity ,010504 meteorology & atmospheric sciences ,Regeneración ,Japón ,Forests ,Oxygen Isotopes ,01 natural sciences ,Trees ,Inorganic Chemistry ,Soil ,Desastres ,Japan ,Environmental Chemistry ,Photosynthesis ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,0105 earth and related environmental sciences ,General Environmental Science ,Carbon Isotopes ,biology ,Nitrogen Isotopes ,Forestry ,biology.organism_classification ,Pinus ,Fenómenos atmosféricos ,Bosques ,%22">Pinus ,Pinus thunbergii ,Tsunamis ,Environmental science ,010606 plant biology & botany - Abstract
The March 2011 Mega-Tsunami in eastern Japan damaged at different degrees the black pine (Pinus thunbergii) forests along the coast. In order to evaluate the recovery of black pine four years later, tree-ring samples from 9 trees for the period 2002-2014 were analyzed for ring growth and stable isotopes (δ
- Published
- 2018
21. Thermodynamics of amide + amine mixtures. 4. Relative permittivities of N,N-dimethylacetamide + N-propylpropan-1-amine, + N-butylbutan-1-amine, + butan-1-amine, or + hexan-1-amine systems and of N,N-dimethylformamide + aniline mixture at several temperatures. Characterization of amine + amide systems using ERAS
- Author
-
Ana Cobos, Juan Antonio González, Fernando Hevia, L.F. Sanz, and Isaías García de la Fuente
- Subjects
Inorganic chemistry ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Dimethylacetamide ,chemistry.chemical_compound ,Aniline ,020401 chemical engineering ,Amide ,Excess functions ,Molecule ,General Materials Science ,ERAS ,0204 chemical engineering ,Physical and Theoretical Chemistry ,Amines ,Equilibrium constant ,Kirkwood correlation factor ,Amides ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,chemistry ,Permittivity ,N dimethylformamide ,Amine gas treating ,Correlation factors - Abstract
Producción Científica, Relative permittivities at 1 MHz and at (293.15-303.15) K are reported for the binary systems N,N-dimethylacetamide (DMA) + N-propylpropan-1-amine (DPA), + N-butylbutan-1-amine (DBA), + butan-1-amine (BA) or + hexan-1-amine (HxA) and for N,N-dimethylformamide (DMF) + aniline. The excess permittivities are large and negative for systems with DMA, whereas they are large and positive for the aniline mixture. From the analysis of these excess permittivity data and of measurements previously reported, it is concluded: (i) the main contribution to the excess permittivity in systems with linear amines arises from the breaking of interactions between like molecules; (ii) in the DMF + aniline mixture, interactions between unlike molecules contribute positively to the excess permittivity, and such a contribution is dominant; (iii) longer linear amines are better breakers of the amide-amide interactions; (iv) interactions between unlike molecules are more easily formed when shorter linear amines, or DMF, participate. These findings are confirmed by a general study conducted in terms of excess values of molar orientational and induced polarizabilities and of the relative Kirkwood correlation factors for systems and components. The ERAS model is also applied to amide + amine mixtures. ERAS represents rather accurately the excess enthalpies and volumes of the mentioned systems. The variation of the cross-association equilibrium constants, determined using ERAS, with the molecular structure is in agreement with that observed for the excess permittivity., The authors gratefully acknowledge the financial support received from the Consejería de Educación y Cultura of Junta de Castilla y León, under Project BU034U16. F. Hevia and A. Cobos are grateful to Ministerio de Educación, Cultura y Deporte for the grants FPU14/04104 and FPU15/05456 respectively.
- Published
- 2018
22. La Lírica Medieval En El Medio Digital. Edición E Interoperabilidad En El Siglo Xxi
- Author
-
Martínez Cantón and Clara Isabel
- Subjects
Pharmacology ,Ecology ,Chemical Sciences not elsewhere classified ,Physiology ,Science Policy ,edición digital ,Biophysics ,Computational Biology ,Plant Biology ,Marine Biology ,Cell Biology ,poesía ,16. Peace & justice ,métrica ,Inorganic Chemistry ,Sociology ,Medicine ,interoperabilidad ,Molecular Biology ,humanidades digitales ,Neuroscience ,Biological Sciences not elsewhere classified - Abstract
Cuando hablamos de nuevas formas y espacios de circulación de la producción cultural en la actualidad estamos hablando, si bien no solo, principalmente, de su presencia en el medio digital. En esta charla se presentan los diferentes proyectos de Humanidades Digitales llevados a cabo desde el grupo del LINHD que tienen como nexo común un mismo objeto de estudio: la lírica medieval castellana y la métrica: Remetca, Diálogo Medieval, Poetriae y, por último, POSTDATA-.
- Published
- 2017
23. Desarrollo de habilidades de pensamiento crítico en torno a la formulación y nomenclatura de la química inorgánica a través del diseño de estrategias didácticas mediadas por las TIC
- Author
-
Álvarez Morales, Andrea and Patiño Franco, Yoany Andrés
- Subjects
Química-Métodos de aprendizaje ,Learning process ,Chemistry-Learning methods ,Proceso de aprendizaje ,Pensamiento crítico ,Química inorgánica ,Critical thinking ,Inorganic chemistry - Abstract
Desde la infancia hasta la adolescencia, el sistema educativo se encarga de formar a los estudiantes en conocimientos, pero las demandas de la sociedad actual requieren que potenciemos en ellos habilidades que le permitan expresar de un modo personal la realidad, identificar las partes de un fenómeno para conocer sus principios, así hacerlo comprensible a los demás, estas tres habilidades son características de un pensador critico. Relacionar el pensamiento crítico con la adquisición de destrezas sobre la formulación y nomenclatura de la química inorgánica mediante el diseño de diferentes estrategias de enseñanza, entre ellas las TIC fue el interés de la investigación realizada en el Instituto Universitario de la ciudad de Manizales. A partir de técnicas como entrevista, encuesta y la observación, se identifico las transformaciones de las habilidades de pensamiento crítico en los estudiantes. From childhood to adolescence, the educational system is in charge of training students in knowledge, but the demands of today's society require that we enhance in them skills that allow them to express reality in a personal way, identify the parts of a phenomenon To know its principles, thus making it understandable to others, these three skills are characteristic of a critical thinker. Relate critical thinking with the acquisition of skills on the formulation and nomenclature of inorganic chemistry through the design of different teaching strategies, including ICT was the interest of the research carried out at the University Institute of the city of Manizales. Using techniques such as interview, survey and observation, the transformations of critical thinking skills in students were identified.
- Published
- 2017
24. Influence of Cobalt Precursor on Efficient Production of Commercial Fuels over FTS Co/SiC Catalyst
- Author
-
Fernando Dorado, José Luis Valverde, Paula Sánchez, Amaya Romero, and Ana Raquel de la Osa
- Subjects
inorganic chemicals ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,lcsh:Chemical technology ,010402 general chemistry ,01 natural sciences ,Chloride ,Catalysis ,lcsh:Chemistry ,commercial fuels ,Adsorption ,Desorption ,β-SiC support ,Precursores de cobalto ,medicine ,Fischer–Tropsch ,cobalt precursors ,lcsh:TP1-1185 ,Combustibles comerciales ,Soporte de β-SiC ,Physical and Theoretical Chemistry ,Fischer–Tropsch process ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,lcsh:QD1-999 ,chemistry ,Commercial fuels ,Cobalt precursors ,0210 nano-technology ,Cobalt ,medicine.drug ,Syngas ,Space velocity - Abstract
β-SiC-supported cobalt catalysts have been prepared from nitrate, acetate, chloride and citrate salts to study the dependence of Fischer–Tropsch synthesis (FTS) on the type of precursor. Com/SiC catalysts were synthetized by vacuum-assisted impregnation while N2 adsorption/desorption, XRD, TEM, TPR, O2 pulses and acid/base titrations were used as characterization techniques. FTS catalytic performance was carried out at 220 °C and 250 °C while keeping constant the pressure (20 bar), space velocity (6000 Ncm3/g·h) and syngas composition (H2/CO:2). The nature of cobalt precursor was found to influence basic behavior, extent of reduction and metallic particle size. For β-SiC-supported catalysts, the use of cobalt nitrate resulted in big Co crystallites, an enhanced degree of reduction and higher basicity compared to acetate, chloride and citrate-based catalysts. Consequently, cobalt nitrate provided a better activity and selectivity to C5+ (less than 10% methane was formed), which was centered in kerosene-diesel fraction (α = 0.90). On the contrary, catalyst from cobalt citrate, characterized by the highest viscosity and acidity values, presented a highly dispersed distribution of Co nanoparticles leading to a lower reducibility. Therefore, a lower FTS activity was obtained and chain growth probability was shortened as observed from methane and gasoline-kerosene (α = 0.76) production when using cobalt citrate, Se han preparado catalizadores de cobalto soportados en β-SiC a partir de sales de nitrato, acetato, cloruro y citrato para estudiar la dependencia de la síntesis de Fischer-Tropsch (FTS) del tipo de precursor. Los catalizadores Co m /SiC se sintetizaron mediante impregnación asistida por vacío, mientras que la adsorción/desorción de N 2 , XRD, TEM, TPR, pulsos de O 2 y titulaciones ácido/base se utilizaron como técnicas de caracterización. El desempeño catalítico de FTS se llevó a cabo a 220 °C y 250 °C manteniendo constante la presión (20 bar), la velocidad espacial (6000 Ncm 3 /g·h) y la composición del gas de síntesis (H 2/CO:2). Se encontró que la naturaleza del precursor de cobalto influye en el comportamiento básico, el grado de reducción y el tamaño de las partículas metálicas. Para los catalizadores con soporte de β-SiC, el uso de nitrato de cobalto resultó en grandes cristalitos de Co, un mayor grado de reducción y una mayor basicidad en comparación con los catalizadores basados en acetato, cloruro y citrato. En consecuencia, el nitrato de cobalto proporcionó una mejor actividad y selectividad a C 5 +(se formó menos del 10% de metano), que se centró en la fracción de queroseno-diésel (α = 0,90). Por el contrario, el catalizador a partir de citrato de cobalto, caracterizado por los valores más altos de viscosidad y acidez, presentó una distribución altamente dispersa de nanopartículas de Co que conduce a una menor reducibilidad. Por lo tanto, se obtuvo una menor actividad de FTS y se acortó la probabilidad de crecimiento de la cadena como se observa en la producción de metano y gasolina-queroseno (α = 0.76) cuando se usa citrato de cobalto
- Published
- 2016
25. Synthesis and modification of beta zeolite for use in toluene disproportionation reaction
- Author
-
Adriana Echavarría, Johana Arboleda, and Santiago Mesa
- Subjects
lcsh:TN1-997 ,Passivation ,Zeolita Beta ,Inorganic chemistry ,Disproportionation ,02 engineering and technology ,010402 general chemistry ,lcsh:Technology ,01 natural sciences ,Catalysis ,chemistry.chemical_compound ,Beta zeolita ,Pasivación Superficial ,Deposition (phase transition) ,Toluene Disproportionation ,Catálisis ,Zeolite ,Desproporción de Tolueno ,lcsh:Mining engineering. Metallurgy ,Inert ,lcsh:T ,Chemistry ,General Engineering ,021001 nanoscience & nanotechnology ,Toluene ,0104 chemical sciences ,Para-selectividad ,62 Ingeniería y operaciones afines / Engineering ,Para-selectivity ,Surface Passivation ,0210 nano-technology ,Layer (electronics) - Abstract
En este trabajo se sintetizó la zeolita Beta y se caracterizó por las técnicas de DRX, ATG, ATD, FRX y MEB. Posteriormente se realizaron diversas modificaciones mediante un proceso de pasivación superficial en fase líquida, usando tetraetilortosilicato (TEOS), utilizando dos cargas de TEOS y tres ciclos de pasivación, dando lugar a 6 catalizadores. Dichos materiales fueron caracterizados por medio de NH3-DTP y probados en la reacción de desproporción de tolueno, bajo diferentes condiciones de presión y temperatura. A medida que se incrementaron los ciclos de modificación para cada catalizador, se generó un cambio en la acidez de los sólidos debido principalmente a la deposición de una capa inerte de sílica sobre la superficie externa, corroborado con el mejoramiento en la para-selectividad y la disminución de la conversión de los sólidos modificados. A pesar que la zeolita Beta es una zeolita de poro grande, se logró un mejoramiento de la para-selectividad, logrando valores casi estables para todo el rango de condiciones evaluadas. In this paper zeolite Beta was synthesized and characterized by XRD, ATG, ATD, XRF and SEM. Subsequently various modifications were made using a surface passivation process in liquid phase with tetraethylorthosilicate (TEOS), using two loads of TEOS and three passivation cycles, in order to obtain six catalysts. These materials were characterized by NH3-TPD and tested in tolune disproportionation reaction, under different conditions of pressure and temperature. As modification cycles were increased for each catalyst, there was a change in the acidity of the solids, mainly due to deposition of an inert layer of silica on the external surface. These results were confirmed with the improvement in para-selectivity and decreasing in conversion. Despite zeolite Beta is a large pore zeolite, an improvement of the para-selectivity was obtained, achieving almost stable values for the entire range of temperature and pressure conditions.
- Published
- 2016
26. Study of the adsorption capacity of Fe(II) dissolved in water by using a mineral rich in Manganese Dioxide (MnO2) from Colombia
- Author
-
Jhonnathan Machado-Infante, Gustavo E. Ramírez-Caballero, and Martha Barajas-Meneses
- Subjects
lcsh:TN1-997 ,Adsorción máxima ,Kinetics ,Inorganic chemistry ,chemistry.chemical_element ,Manganese ,engineering.material ,lcsh:Technology ,Isotherms ,symbols.namesake ,Cinética ,Adsorption ,Oxidizing agent ,lcsh:Mining engineering. Metallurgy ,Pyrolusite ,Aqueous solution ,Chemistry ,lcsh:T ,Adsorción de Fe (II) ,Adsorption of Fe (II) ,General Engineering ,Langmuir adsorption model ,Maximum adsorption ,Isotermas ,62 Ingeniería y operaciones afines / Engineering ,symbols ,engineering ,Water treatment ,MnO2 - Abstract
En Colombia, un mineral rico en MnO2 es extraído de las minas de Mallama, Nariño. En este trabajo se estudió la capacidad de adsorción de Fe(II) del agua en sistemas abiertos de este mineral. La caracterización del mineral se hizo a través de ICP-AES, XRF y Espectroscopía Raman. Se evaluó el efecto de diferentes pretratamientos realizados al mineral con agentes oxidantes como KMnO4 y NaClO. Los estudios de equilibrio y cinética de adsorción demostraron que el mecanismo se adapta muy bien a la isoterma de Langmuir y su cinética a un modelo de pseudo-segundo orden. A las condiciones estudiadas se encontró que la capacidad de adsorción del mineral tratado con KMnO4 y NaClO fue 59,209 y 51,279 mg/g respectivamente. Se concluye que el mineral presenta alto potencial en el tratamiento de aguas. In Colombia, a mineral rich in MnO2 is extracted from the mines of Mallama, Nariño. In this work we studied the adsorption capacity of this mineral for Fe(II) dissolved in aqueous solution of open systems. The characterization was done through ICP-AES, XRF and Raman spectroscopy. The effect of different pretreatments on the mineral with oxidizing agents such as KMnO4 and NaClO was evaluated. Studies of equilibrium and kinetics of adsorption showed that the mechanism fits well to the Langmuir isotherm and its kinetics to a model of pseudo-second order. At the conditions studied was found that the adsorption capacity for the mineral modified with KMnO4 and NaOCl were 59.209 and 51.279 mg/g respectively. It is concluded that the mineral is a potential alternative in water treatment.
- Published
- 2016
27. Deposition of Sn in polycrystalline Pt for use in the oxidation of Methanol
- Author
-
Javier E. Rodríguez-Yáñez
- Subjects
Estaño ,voltamperometría ,Inorganic chemistry ,chemistry.chemical_element ,Electrochemistry ,Industrial and Manufacturing Engineering ,Metal ,chemistry.chemical_compound ,Adsorption ,platino ,electrocatalysis ,espontáneo ,platinum ,spontaneous ,methanol ,voltammetry ,upd ,subpotencial ,Sulfuric acid ,electrocatálisis ,chemistry ,Tin ,visual_art ,visual_art.visual_art_medium ,Methanol ,Platinum ,Deposition (chemistry) ,metanol - Abstract
Resumen Se evaluaron tres diferentes métodos de deposición de estaño en platino policristalino (Pt pc) desde una solución de ácido sulfúrico utilizando técnicas electroquímicas convencionales, con el fin de determinar y comparar su influencia en la oxidación de metanol. Los métodos probados fueron deposición espontánea, deposición a subpotenciales y deposición cíclica a subpotenciales. El estaño fue depositado desde una solución de SnSO4 en ácido sulfúrico. Se utilizó la reducción del perfil voltamétrico en el área de adsorción de hidrógeno en el platino por el estaño para calcular el grado de cubrimiento de la superficie por el mismo. La adsorción de metanol y su oxidación se compararon entre los electrodos de platino y platino/ estaño, considerando la eficiencia de oxidación de metanol con respecto al área libre de platino como parámetro comparativo. Abstract Three different tin deposition methods on a polycrystalline platinum electrode in sulfuric acid were studied by conventional electrochemical techniques, in order to determine and compare their influence on methanol oxidation. The deposition methods tested were spontaneous deposition, under potential deposition and cyclic under potential deposition. Tin was deposited from a solution of SnSO4 in sulfuric acid. The inhibition of the hydrogen adatom voltammetric profile on platinum by tin metal ion was used to calculate the degree of surface coverage due to tin deposition. Methanol adsorption and oxidation were compared on platinum and platinum/tin electrodes, considering the efficiency of methanol oxidation with respect to the platinum free area.
- Published
- 2016
28. Carbon nanofiber-based palladium/zinc catalysts for the hydrogenation of carbon dioxide to methanol at atmospheric pressure
- Author
-
J. Díez-Ramírez, Fernando Dorado, José Luis Valverde, Alberto Rodríguez-Gómez, and Paula Sánchez
- Subjects
Alcoholes ,Nanofibras ,Materials science ,General Chemical Engineering ,Alloy ,Inorganic chemistry ,Nanofibers ,chemistry.chemical_element ,02 engineering and technology ,Zinc ,engineering.material ,010402 general chemistry ,01 natural sciences ,Industrial and Manufacturing Engineering ,Catalysis ,chemistry.chemical_compound ,Alloys ,Aleaciones ,Catalysts ,Carbon nanofiber ,Catalizadores ,Oxides ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Nanofiber ,Alcohols ,engineering ,Methanol ,Particle size ,0210 nano-technology ,Palladium ,Óxidos - Abstract
Palladium/zinc catalysts supported on carbon nanofibers (CNFs) have been used to study the catalytic performance in the hydrogenation of CO2 to obtain methanol at atmospheric pressure. The carbon nanofiber support has an influence on the nature of the PdZn alloy formed. The effect of the Pd/Zn molar ratio on the PdZn alloy particle size was analyzed. Lower Pd/Zn molar ratio leads to higher PdZn alloy particle size, which was associated with higher selectivity toward methanol. The influence of the type of nanofiber (platelet or fishbone) on the catalytic behavior was also studied and compared with that of a conventional Pd/ZnO catalyst. The palladium/zinc catalyst supported on platelet nanofiber was considered to be a good candidate for the hydrogenation of carbon dioxide to methanol., Se han utilizado catalizadores de paladio/zinc soportados sobre nanofibras de carbono (CNFs) para estudiar el rendimiento catalítico en la hidrogenación de CO 2 para obtener metanol a presión atmosférica. El soporte de nanofibras de carbono influye en la naturaleza de la aleación de PdZn formada. Se analizó el efecto de la relación molar Pd/Zn sobre el tamaño de partícula de la aleación de PdZn. Una relación molar más baja de Pd/Zn conduce a un tamaño de partícula de aleación de PdZn más alto, lo que se asoció con una mayor selectividad hacia el metanol. También se estudió la influencia del tipo de nanofibra (plaqueta o espina de pescado) en el comportamiento catalítico y se comparó con el de un catalizador convencional de Pd/ZnO. El catalizador de paladio/zinc soportado sobre nanofibras de plaquetas se consideró un buen candidato para la hidrogenación de dióxido de carbono a metanol.
- Published
- 2016
29. Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States
- Author
-
Ana María Gómez-Caravaca, Vito Verardo, Antonio Segura-Carretero, Elixabet Díaz-de-Cerio, and Alberto Fernández-Gutiérrez
- Subjects
0301 basic medicine ,Cyanidin-glucoside ,Flavonols ,phenolic compounds ,01 natural sciences ,Catalysis ,Article ,Antioxidants ,lcsh:Chemistry ,Inorganic Chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,Nutraceutical ,Phenols ,Botany ,gallic and ellagic derivatives ,Hypoglycemic Agents ,Gallic and ellagic derivatives ,Food science ,Physical and Theoretical Chemistry ,lcsh:QH301-705.5 ,Molecular Biology ,Spectroscopy ,chemistry.chemical_classification ,Folk medicine ,Psidium ,HPLC-DAD-ESI-QTOF-MS ,030109 nutrition & dietetics ,Plant Extracts ,010401 analytical chemistry ,Organic Chemistry ,General Medicine ,flavonols ,Phenolic compounds ,0104 chemical sciences ,Computer Science Applications ,Plant Leaves ,lcsh:Biology (General) ,lcsh:QD1-999 ,chemistry ,Psidium guajava L ,cyanidin-glucoside ,Composition (visual arts) - Abstract
Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high). The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production.
- Published
- 2016
30. Procesado Láser de Materiales Cerámicos: Síntesis y modificación superficial
- Author
-
Pedra Tellols, José Miguel, Carda Castelló, Juan Bautista, De la Fuente Leis, Germán Francisco, Lahoz Espinosa, Ruth, and Universitat Jaume I. Departament de Química Inorgànica i Orgànica
- Subjects
Inorganic Chemistry ,Química Inorgánica ,Ceramología ,Química del estado sólido ,Ceramology ,Ciències ,Dispositivos láser ,Chemistry of the solid state ,Laser devices - Abstract
La tecnología láser es una técnica ampliamente utilizada en el procesado de materiales, especialmente en aquellos en los que se requieren la aplicación de tratamientos térmicos a altas temperaturas en áreas muy localizadas y con una gran precisión. En la presente tesis doctoral se muestran algunos ejemplos de aplicación de la radiación láser a materiales cerámicos de diversa naturaleza con tipos diferentes de procesado. Así, respecto a los tipos de procesado se han estudiado la fusión y la ablación: la fusión se ha utilizado para la obtención de pigmentos cerámicos, tanto convencionales como nuevos, a partir de sus componentes precursores básicos (óxidos) y en ausencia de otros aditivos o catalizadores. Asimismo, también se ha utilizado para la síntesis de capas continuas de recubrimientos de tipo composite, con composiciones MTi-Al-O y M-Zr-Al-O (donde M = Ca, Sr, Ba) sobre soportes de alúmina sinterizada. en cuanto a la ablación, se ha empleado para la mecanización de relieves sobre soportes cerámicos estándar típicos de la industria cerámica, como la pasta de porosa o el gres porcelánico. Se han estudiado tanto los productos finales como las partículas resultantes de la ablación, para determinar el rendimiento del proceso o la influencia de los diferentes parámetros en el proceso. Para finalizar, se muestran los resultados obtenidos de la combinación de ambos tipos de procesado aplicados a la fabricación de productos cerámicos tradicionales, como son los azulejos y baldosas. En este caso, se han ablacionado los soportes para conseguir los relieves deseados y, posteriormente, se ha aplicado el láser para conseguir la síntesis in situ de pigmentos directamente sobre el soporte cerámico, para realizar la decoración cromática del producto final.
- Published
- 2015
31. Métodos no convencionales para la preparación de polímeros de coordinación porosos. Una aproximación económica, medioambientalmente amigable y escalable
- Author
-
Lanchas González, Mónica, Castillo García, Oscar, Beobide Pacheco, Garikoitz, Química inorgánica, and Kimika Ez-organikoa
- Subjects
coordination compounds ,estructura de los compuestos inorgánicos ,inorganic chemistry ,química inorgánica ,compuestos coordinados ,structure of inorganic compounds - Abstract
293 p. El contenido del capítulo 5 está sujeto a confidencialidad, En la última década, se ha puesto de relieve una nueva clase de material cristalino poroso con esqueleto híbrido, formado por la unión de iones o clústeres metálicos a través de ligandos puentes, los MOFs (Metal-Organic Frameworks). El gran auge de este tipo de materiales se debe a su versatilidad estructural y funcional, que hace de ellos excelentes candidatos para su aplicación en diferentes campos, como almacenamiento de combustibles gaseosos, separación y purificación de gases, catálisis heterogénea, sensórica, transporte y liberación de fármacos, etc. Hasta la fecha, la mayoría de las investigaciones se han centrado en desarrollar nuevos MOFs, analizar sus propiedades y explorar nuevas aplicaciones, sin reparar en los inconvenientes de sus síntesis que limitan su explotación comercial. Entre estos inconvenientes destacan el uso de disolventes tóxicos, reactores y técnicas difíciles de implementar a gran escala, además del empleo de ligandos costosos, complejos y no comerciales. Con el fin de buscar alternativas que ayuden a fomentar el mercado de los MOFs y su aplicación comercial, la presente memoria de Tesis propone diversas aproximaciones sintéticas. En primer lugar, se establece por vez primera la síntesis de MOFs en ausencia de disolvente asistida mediante calentamiento convencional e irradiación microondas. La ausencia de disolvente, hace de la síntesis un proceso medioambientalmente más sostenible, económico, seguro y fácilmente escalable a nivel industrial. Asimismo, se han explorado diversas rutas de síntesis para realizar modificaciones microestructurales que permitan obtener MOFs ultraporosos (3062-6032 m2¿g-1) y MOFs meso/macroporosos (20-180 nm) a costes comparativamente bajos, empleando siempre ligandos sencillos y disolventes verdes.
- Published
- 2015
32. 3-Methylpiperidinium ionic liquids
- Author
-
Geetha Srinivasan, Keith Whiston, Kenneth R. Seddon, Alberto V. Puga, Mark Nieuwenhuyzen, Tayeb Belhocine, H. Q. Nimal Gunaratne, Peter Nockemann, and Stewart Forsyth
- Subjects
chemistry.chemical_classification ,Tetraphenylborate ,Inorganic chemistry ,General Physics and Astronomy ,Ether ,Crystal structure ,Ion ,chemistry.chemical_compound ,chemistry ,Bromide ,Ionic liquid ,QUIMICA ANALITICA ,Ionic conductivity ,Physical chemistry ,Physical and Theoretical Chemistry ,Alkyl - Abstract
[EN] A wide range of room temperature ionic liquids based on the 3-methylpiperdinium cation core were produced from 3-methylpiperidine, which is a derivative of DYTEKs (R) A amine. First, reaction with 1-bromoalkanes or 1-bromoalkoxyalkanes generated the corresponding tertiary amines (Rm beta pip, R = alkyl or alkoxyalkyl); further quaternisation reactions with the appropriate methylating agents yielded the quaternary [Rmm(beta)pip]X salts (X-= I-, [CF3CO2]-or [OTf](-); Tf = -SO2CF3), and [Rmm(beta)pip][NTf2] were prepared by anion metathesis from the corresponding iodides. All [NTf2]-salts are liquids at room temperature. [Rmm(beta)pip]X (X-= I-, [CF3CO2]-or [OTf](-)) are low-melting solids when R = alkyl, but room temperature liquids upon introduction of ether functionalities on R. Neither of the 3-methylpiperdinium ionic liquids showed any signs of crystallisation, even well below 0 degrees C. Some related non-C-substituted piperidinium and pyrrolidinium analogues were prepared and studied for comparison. Crystal structures of 1-hexyl-1,3-dimethylpiperidinium tetraphenylborate, 1-butyl-3-methylpiperidinium bromide, 1-(2-methoxyethyl)1- methylpiperidinium chloride and 1-(2-methoxyethyl)-1-methylpyrrolidinium bromide are reported. Extensive structural and physical data are collected and compared to literature data, with special emphasis on the systematic study of the cation ring size and/or asymmetry effects on density, viscosity and ionic conductivity, allowing general trends to be outlined. Cyclic voltammetry shows that 3-methylpiperidinium ionic liquids, similarly to azepanium, piperidinium or pyrrolidinium counterparts, are extremely electrochemically stable; the portfolio of useful alternatives for safe and high-performing electrolytes is thus greatly extended., We would like to acknowledge the EPSRC NCS in Southampton for the single crystal X-ray diffraction data collection and INVISTA Intermediates for funding.
- Published
- 2015
33. ADSORPTION OF HEAVY METALS USING ACTIVATED CARBONS PREPARED FROM AGUAJE STONES
- Author
-
Javier Aylas-Orejón, Ana Lucía Paredes-Doig, Daniel Obregón-Valencia, Angela Pinedo-Flores, and María del Rosario Sun-Kou
- Subjects
semillas de aguaje ,Scanning electron microscope ,cadmium ,Inorganic chemistry ,chemistry.chemical_element ,cromo ,carbón activado ,chemistry.chemical_compound ,Chromium ,Adsorption ,medicine ,activated carbon ,cadmio ,Phosphoric acid ,General Environmental Science ,Cadmium ,lead ,plomo ,aguaje stones ,Sorption ,chemistry ,General Earth and Planetary Sciences ,Titration ,chromium ,Activated carbon ,medicine.drug - Abstract
La semilla de aguaje (fruto típico de la selva amazónica) fue empleada como un material precursor para la preparación de carbón activado usando ácido fosfórico como agente activante en dos concentraciones diferentes: 0,75 y 1,0 g /g . Las propiedades H3PO4 Precursor fisicoquímicas se estudiaron mediante mediciones de adsorción de nitrógeno, titulación Boehm, microscopía electrónica de barrido y espectroscopía de rayos X por energía dispersiva. Los carbones activados se utilizaron en la adsorción de tres metales pesados: plomo, cadmio y cromo. La máxima capacidad de adsorción se logró utilizando el carbón activado AG0,75_600 con soluciones con un pH mayor a 4; los valores obtenidos estaban en el -1 -1 -1 siguiente orden: plomo (74,8 mg g ) , cadmio (26,5 mg g ), cromo (18,8 mg g ). Los factores más importantes que influyen en el proceso de adsorción fueron el pH de la solución, la estructura porosa y la acidez superficial del carbón activado. Aguaje seed (a typical Amazonian forest fruit) was used as a precursor material for the production of activated carbon using phosphoric acid as activating agent in two different concentrations: 0,75 and 1,0 gH3PO4/gPrecursor. The physicochemical properties were studied by N2 sorption measurements, Boehm titration, scanning electron microscopy and energydispersive X-ray spectroscopy. Activated carbons were used in the adsorption of three heavy metals: lead, cadmium and chromium. The maximum adsorption capacity was achieved using activated carbon AG0,75_600 in a solution with a pH greater than 4 and the values -1 -1 obtained were in the following order: lead (74,8 mg g ), cadmium (26,5 mg g ), chromium -1 (18,8 mg g ). The most important factors influencing the adsorption process were the pH of the solution, the porous structure and surface acidity of the activated carbon.
- Published
- 2014
- Full Text
- View/download PDF
34. HYDROGEN STORAGE IN Mg BASED MATERIALS DOPPED WITH TINY AMOUNTS OF LiBH4 AND Fe HALIDES (FeF3 Y FeCl3)
- Author
-
Fabiana C. Gennari, Julián Puszkiel, and P. Arneodo Larochette
- Subjects
Hydrogen storage ,magnesium hydride ,Materials science ,Inorganic chemistry ,milling ,General Physics and Astronomy ,Halide ,hydrogen storage - Abstract
The high thermodynamic stability of MgH2 results in a hydrogen release temperature of 300 ºC at 1 atm. Due to kinetic constraints the dehydriding temperatures of MgH2 in dynamic conditions are even higher. Moreover, long dehydriding times are required. In this work, materials composed of Mg plus tiny amounts of LiBH4 doped with FeF3 and FeCl3 are studied. The addition of tiny amounts of LiBH4 to Mg during the milling process noticeably modifies size and morphology of the Mg agglomerates. On one hand, the sizes of Mg agglomerates are markedly reduced. On the other hand, pits and cracks, which enhance hydrogen diffusion during hydriding, are generated upon the Mg agglomerates. These structural changes give rise to larger hydrogen capacities without modifying the thermodynamic behavior of the Mg–H system. However, the hydrogen release at low temperatures (≤ 300 ºC) is still slow. Thus, it is proposed the FeF3 and FeCl3 doping in order to improve the kinetic behavior of the Mg + tiny amounts of LiBH4 material. Throughout the milling and hydrogen sorption processes Fe halides react with LiBH4 to form FeB species. Experimental results suggest that the in-situ formation of MgH2 during milling allows the further Mg agglomerate size reduction between 5 and 50 μm for the 85mol%Mg–10mol%LiBH4– 5mol%FeCl3 material. The additional Mg agglomerate reduction along with the FeB dispersion, which might have catalytic properties, reduce the activation energy for hydrogen release about 20 kJ/mol H2 in comparison with 90mol%Mg–10mol%LiBH4. This leads to faster hydrogen desorption rate and reversible hydrogen capacities of about 5 wt. % at 275 ºC.
- Published
- 2014
- Full Text
- View/download PDF
35. Estudio espectroscópico y termodinámico de la adsorción de gases en redes metalo-orgánicas
- Author
-
Palomino Cabello, Carlos, Departament de Química, and Turnes Palomino, Gemma
- Subjects
Inorganic Chemistry ,Technology Chemistry - Abstract
[spa] Se han preparado sólidos porosos constituidos por redes metalo-orgánicas (MOFs) pertenecientes a las familias MOF-74, MIL-101 y MIL-100 mediante la optimización de rutas de síntesis solvotermal ya conocidas. Los materiales obtenidos se han caracterizado mediante difracción de rayos X, microscopía electrónica, análisis termogravimétrico y espectroscopía FTIR. La naturaleza y accesibilidad de los centros metálicos coordinativamente insaturados presentes en las muestras ha sido estudiada haciendo uso de espectroscopía IR de CO adsorbido. Estudios mediante espectroscopía FTIR del H2 y el CO2 adsorbido a temperatura variable han permitido determinar los correspondientes valores de entalpía (H0) y entropía (S0) estándar de adsorción del hidrógeno y el dióxido de carbono en las redes metalo-orgánicas preparadas. Los estudios termodinámicos realizados han permitido además demostrar la existencia de una correlación positiva (no lineal) entre los valores de H0 y S0 tanto del hidrógeno como del dióxido de carbono. Los valores de entalpía estándar de adsorción obtenidos en ambos casos para las redes metal-orgánicas estudiadas se encuentran entre los más altos publicados hasta el momento para MOFs que contienen cationes coordinativamente insaturados. Estos resultados corroboran que la incorporación de centros metálicos con elevada densidad de carga mejora la afinidad de este tipo de materiales por el H2 y el CO2 a bajas presiones, lo que puede conducir a la obtención de materiales adsorbentes óptimos para su uso tanto en el almacenamiento eficiente (a bajo coste) de hidrógeno como para la captura de dióxido de carbono., [cat] S’han preparat sòlids porosos constituïts per xarxes metal·lorgàniques (MOFs) pertanyents a les famílies MOF-74, MIL-101 i MIL-100 mitjançant l’optimizació de rutes de síntesi solvotermal ja conegudes. Els materials obtinguts s’han caracteritzat mitjançant difracció de raigs X, microscòpia electrònica, anàlisi termogravimètrica i espectroscòpia FTIR. La naturalesa i accessibilitat dels centres metàl•lics coordinativament insaturats presents en les mostres ha estat estudiada fent ús d’espectrocòpia IR de CO adsorbit. Estudis mitjançant espectroscòpia FTIR de l’H2 i el CO2 adsorbit a temperatura variable han permès determinar els corresponents valors d’entalpia (H0) i entropía (S0) estàndard d’adsorció de l’hidrogen i el diòxid de carboni en les xarxes metal•lorgàniques preparades. Els estudis termodinàmics realitzats han permès a més demostrar l’existència d’una correlació positiva (no lineal) entre els valors de H0 i S0 tant de l’hidrogen com del diòxid de carboni. Els valors d’entapia estándar d’adsorció obtinguts en ambos casos per a les xarxes metal•lorgàniques estudiades es troben entre els més alts publicats fins ara per MOFs que contenen cations coordinativament insaturats. Aquests resultats corroboren que la incorporació de centres metàl•lics amb elevada densitat de càrrega millora l’afinitat d’aquest tipus de materials pel H2 i el CO2 a baixes pressions, el que pot conduir a l’obtenció de materials adsorbents òptims per al ser ús tant en l’emmagatzematge eficient (a baix cost) d’hidrogen com per a la captura de diòxid de carboni., [eng] The main goal of this thesis has been focused on the study of gender differences in the mitochondrial morphology, function and biogenesis both in brown adipose tissue (BAT) and in liver, through the analysis of the several mitochondrial subpopulations isolated by means of the fractionation of the whole mitochondrial population. Results have reflected that the gender dimorphism stated in mitochondrial population both in BAT and in liver could be attributed to the existence to more highly differentiated mitochondria in female rats, which could be the result of a different mitochondrial biogenesis process between genders. Since the existence of a common factor which influences this process in both tissues could be hypothesized, sexual hormones could be one of the main factors responsible for the differences described in the present work.
- Published
- 2014
36. PANORAMA DA QUÍMICA INORGÂNICA NO BRASIL REVISITADO: PERÍODO DE 2002 A 2016
- Author
-
Shirley Nakagaki, Geani Maria Ucoski, Julio S. Rebouças, and Ana Maria da Costa Ferreira
- Subjects
inorganic chemistry ,research in Brazil ,40th SBQ, scientific production ,international cooperation ,Chemistry ,QD1-999 - Abstract
The present article describes the development of the Inorganic Chemistry in Brazil in the last 15 years, using as starting point the scientific contributions of a group of 405 researchers selected among the members of the Inorganic Chemistry Division of the Brazilian Chemical Society (SBQ), and active participants of both SBQ Annual Meetings and Brazilian Meetings on Inorganic Chemistry. A total of 3006 articles, representative of the Brazilian scientific production on Inorganic Chemistry from 2002 to January 2017, was analyzed. Among the various aspects evaluated are: prevalent research topics, production impact, geographic distribution within Brazil, international collaborations, and human resource background, development, and perspectives. The evolution of the Inorganic Chemistry production in Brazil in the last 15 years was analyzed considering the concurrent expansion of Brazilian graduate and post-graduate educational system along with availability of funding resources. Information from sources such as CAPES, Sucupira database, eMEC, Web of Science, and CNPq, complemented the scientific production data gathered from the Curriculum Vitae (Lattes Curriculum database) of the 405 representative inorganic chemistry researchers. The present analysis expands the previous 1977-2001 study by Toma, Ferreira, and Serra (Quim. Nova 2002, 25, 66), depicting, thus, a 40-year scenery of Inorganic Chemistry in Brazil, which overlaps with the period of activity of SBQ.
- Full Text
- View/download PDF
37. Hidrogenación de m-Dinitrobenceno mediante el uso de catalizadores de platino soportados en silice, titania y alúmina
- Author
-
Hugo Rojas, María H. Brijaldo, Gloria Borda, Jesús S. Valencia, and Patricio Reyes
- Subjects
chemistry.chemical_classification ,M-dinitrobenceno ,Hydrogen ,Metal ,Batch reactor ,Inorganic chemistry ,Aromatic amine ,chemistry.chemical_element ,Catalysis ,Solvent ,Amina aromática ,chemistry ,Physisorption ,Selectividad ,Gas chromatography ,Selectivity - Abstract
Los catalizadores Pt/SiO2, Pt/Al2O3 y Pt/TiO2 se prepararon mediante impregnación húmeda, a una concentración del 1% en peso del metal. Los catalizadores resultantes se caracterizaron mediante análisis de difracción de rayos X (DRX), fisisorción de nitrógeno a 77 K y quimisorción de hidrógeno a 298 K. Estos sistemas catalíticos se emplearon en la reacción de hidrogenación de m-dinitrobenceno para la obtención de m-feniléndiamina, una amina aromática de extensa aplicación en el campo de la química fina. Las reacciones se llevaron a cabo en un reactor tipo batch, a 0.82 MPa de presión de hidrógeno, 343 K y etanol como disolvente. Los productos de reacción se siguieron mediante cromatografía de gases. El catalizador Pt/TiO2 exhibió el mayor nivel de conversión de m-dinitrobenceno (91.5 %) y selectividad hacia m-feniléndiamina (72.4 %). Este omportamiento se atribuyó a la presencia fuerte interacción entre el metal y el soporte.
- Published
- 2013
38. Reduction of alkenes catalyzed by copper nanoparticles supported on diamond nanoparticles
- Author
-
Amarajothi Dhakshinamoorthy, Sergio Navalon, Hermenegildo García, Mercedes Alvaro, and David Sempere
- Subjects
Materials science ,Hydrogen ,Annealing (metallurgy) ,Inorganic chemistry ,Generation ,Nanoparticle ,chemistry.chemical_element ,Ethylbenzene ,Catalysis ,Olefins ,Styrene ,chemistry.chemical_compound ,QUIMICA ORGANICA ,Diimide ,Materials Chemistry ,Hydrazine ,Aerobic hydrogenation ,Metals and Alloys ,General Chemistry ,Copper ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Chemistry ,Efficient ,chemistry ,Ceramics and Composites ,Nuclear chemistry - Abstract
Copper nanoparticles (Cu NPs) supported on diamond nanoparticles (D NPs) previously purified by Fenton treatment (Cu/D) followed by annealing with hydrogen (Cu/DH) are highly efficient and reusable heterogeneous catalysts for hydrogenation of styrene to ethylbenzene with the minimum productivity value of 30617 cycles., Financial support from the Spanish Ministry of Science and Education (Consolider MULTICAT, CTQ-2012-32316) is gratefully acknowledged.
- Published
- 2013
39. Simulación del Proceso de Absorción Química con Soluciones de Aminas para la Purificación Biogás
- Author
-
Betzabet del Valle Morero and Enrique Angel Campanella
- Subjects
Strategy and Management ,Inorganic chemistry ,Otras Ingeniería del Medio Ambiente ,INGENIERÍAS Y TECNOLOGÍAS ,Industrial and Manufacturing Engineering ,soluciones de aminas ,purl.org/becyt/ford/1 [https] ,Biogas ,Promax ,purl.org/becyt/ford/1.4 [https] ,Ingeniería del Medio Ambiente ,purificación biogás ,Chemistry ,biogas purification ,purificación de biogás ,Ciencias Químicas ,Geotechnical Engineering and Engineering Geology ,process simulation ,purl.org/becyt/ford/2.7 [https] ,Computer Science Applications ,General Energy ,purl.org/becyt/ford/2 [https] ,Scientific method ,Amine gas treating ,Química Analítica ,Absorption (chemistry) ,simulación de procesos ,CIENCIAS NATURALES Y EXACTAS ,Food Science ,amine solutions - Abstract
The influence of some key operating parameters and of different types of amines in biogas purification is analyzed. For this a conventional single-loop absorber-stripper process configuration was simulated using four types of amines (monoethanolamine, diethanolamine, diglycolamine and methyldiethanolamine) and two mixtures of them. The process simulator ProMax® was used. The variables studied were methane, carbon dioxide, hydrogen sulphide and water concentrations in the sweetened gas, process energy consumption, absorption temperatures and reboiler steam rates. The simulation results showed good levels of purification in all cases with best results for diglycolamine (97.3% de CH4) which also has the lowest reboiler energy consumption. Prior knowledge of natural gas absorber-stripper processes allowed using the technology in the particular case of biogas. Se analiza la influencia de los principales parámetros de operación y de distintos tipos de aminas en la purificación de biogás. Para ello se simuló un proceso convencional de absorción-desorción usando cuatro tipos de aminas (monoetanolamina, dietanolamina, diglicolamina y metildietanolamina) y dos mezclas de ellas. Para los cálculos se usó el simulador de procesos ProMax®. Las variables analizadas fueron la concentración de metano, anhídrido carbónico, ácido sulfhídrico y agua en el gas purificado, el consumo de energía en el proceso, la temperatura de absorción y la tasa de vapor utilizada en el vaporizador. En todos los casos se obtuvieron buenos resultados en los niveles de purificación alcanzados, los mayores niveles se obtuvieron con diglicolamina (97.3% de CH4) que además presenta el menor gasto energético en el vaporizador. Los conocimientos previos sobre sistemas de absorción-desorción de gas natural permitieron adaptar la tecnología al caso particular del biogás. Fil: Morero, Betzabet del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina; Fil: Campanella, Enrique Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET- Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina
- Published
- 2013
40. Characterization and photoluminescence properties of some CaO, SrO and CaSrO2 phosphors co-doped with Eu3+ and alkali metal ions
- Author
-
Bernabé Marí, Mónica Moya, Subhash Chand, Kinjulck C. Singh, Hari Om, and Ishwar Singh
- Subjects
Diffraction ,Photoluminescence ,Morphology (linguistics) ,Materials science ,Eu3+ [SrO] ,Scanning electron microscope ,Analytical chemistry ,Mineralogy ,Phosphor ,Ion ,Inorganic Chemistry ,Crystallinity ,Eu3+, M+ (Li+ , Na+ or K+ ) [CaO] ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Spectroscopy ,SrO:Eu3+ ,Organic Chemistry ,Alkali metal ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,CaSrO2:Eu3+ ,Combustion synthesis ,FISICA APLICADA ,Eu3+ [CaSrO2] ,CaO:Eu3+, M+ (Li+ , Na+ or K+ ) - Abstract
CaO:Eu3+, M+ (Li+ or Na+ or K+ ), SrO:Eu3+and CaSrO2:Eu3+ powders were prepared by combustion synthesis method and the samples were further heated to 1000 C to improve the crystallinity of the materials. The structure and morphology of materials were examined by X-ray diffraction and scanning electron microscopy. The morphology of CaO:Eu3+ and co-doped with alkali metal ions powders was very similar. Small and coagulated particles of nearly cubical shapes with small size distribution having smooth and regular surface were formed. The surface morphology of SrO and CaSrO2 materials was not smooth and coagulated particles of irregular shapes with different sizes were observed. The characteristic emissions of Eu3+ had strong emission at 614 and 620 nm for 5 D0 ? 7 F2 with other weak transitions observed at 580, 592, 654, 705 nm for 5 D0 ? 7 Fn transitions where n = 0, 1, 3, 4 respectively in all host lattices. Photoluminescence intensity followed the order as in CaO > CaSrO2 > SrO lattices. A remarkable increase of photoluminescence intensity was observed by the co-doping of alkali metal ions particularly K+ ions in CaO:Eu3+., This work was supported by Spanish Government through MCINN Grant MAT2009-14625-C03-03. K.C. Singh acknowledges MEC for financial support (SAB2010-0019).
- Published
- 2012
41. Microwave synthesis, spectral, thermal and antimicrobial studies of some Ni(II) and Cu(II) Schiff base complexes
- Author
-
Neha Sharma, A. P. Mishra, and Rajendra K. Jain
- Subjects
Isonicotinic acid hydrazide ,Metal ions in aqueous solution ,Inorganic chemistry ,Análisis térmico ,Facultad de Ciencias ,lcsh:Chemistry ,Metal ,chemistry.chemical_compound ,Microwave synthesis ,Polymer chemistry ,Actividad biológica ,Molecule ,Thermal analysis ,Artículos Científicos [Revista Avances en Química] ,Schiff base ,Revistas ,Thermal study ,Ligand ,Biological activity ,Departamento de Química ,Química ,Revista Avances en Química ,Methyl isobutyl ketone ,lcsh:QD1-999 ,chemistry ,Síntesis por microondas ,visual_art ,visual_art.visual_art_medium ,Hidracina del ácido isonicotínico ,Acetophenone - Abstract
Se sintetizaron bases de Schiff bidentadas y tridentadas (NO), (ONO) a través de la reacción de condensación entre la metil-isobutilcetona y el 2-amino-4clorofonol y 2-hidroxiacetofenona con la hidracina del ácido isonicotínico. Los complejos metálicos 1:1 o 1:2 han sido preparados mediante la interacción de estas bases de Schiff y los iones Ni(II) y Cu(II). La síntesis fue realizada empleando el método convencional y el de microondas, y los productos fueron caracterizados por análisis elemental, FT-IR, UV-Vis, RES, conductancia molar, análisis térmico y difracción de rayos X. Los complejos son coloreados y estables al aire y temperatura ambiente. El comportamiento térmico de los complejos metálicos hidratados muestran una primera etapa de pérdida de agua de hidratación, seguidos de la descomposición de las moléculas de ligando en etapas subsecuentes. El análisis de los cristales del complejo [Ni(HINH)(H2O)]Cl.3H2O a = b = 13,9338Ǻ, c = 34,7975Ǻ, V= 6755, 96Ǻ3, Z = 12, Dobs = 1,2421g/cm3, Dcal 1,2847g/cm3, refleja una estructura cristalina en un sistema ortorómbico. La conductividad eléctrica de estado sólido de los complejos metálicos indica que éstos poseen una naturaleza semiconductora. Las bases de Shiff y los complejos metálicos muestran buena actividad contra bacterias Gram-positivas del tipo Staphylococcus aureus, bacterias Gram-negativas del tipo Escherichia coli y hongos del tipo Aspergillus niger y Candida albicans. Los complejos metálicos son mejores agentes antimicrobiales que las bases de Schiff. Bidentate and tridentate (NO), (ONO) Schiff bases have been synthesized by condensing methyl isobutyl ketone with 2-amino-4-chlorophenol and 2-hydroxy acetophenone with isonicotinic acid hydrazide. The 1:1 or 1:2 metal complexes have been prepared by interacting these Schiff bases with metal ions viz. Ni(II), Cu(II). These compounds have been synthesized by conventional as well as microwave methods and characterized by elemental analysis, FT-IR, UV-Vis, ESR, molar conductance, thermal analysis and X-ray diffraction. The complexes are colored and stable in air at room temperature. The thermal behavior of metal complexes shows that the hydrated complexes loses water molecules of hydration in the first step; followed by decomposition of ligand molecules in the subsequent steps. Crystal data of [Ni(HINH)(H2O)]Cl.3H2O complex a = b =13.9338Ǻ, c = 34.7975Ǻ, V = 6755.96Ǻ3, Z = 12, Dobs = 1.2421g/cm3, Dcal 1.2847g/cm3, reflect that this complex has crystallized in orthorhombic system. The solid state electrical conductivity of the metal complexes has also been measured. Solid state electrical conductivity studies reflect semiconducting nature of the complexes. The Schiff bases and metal complexes show good activity against the Gram-positive bacteria; Staphylococcus aureus and Gram-negative bacteria; Escherichia coli and fungi Aspergillus niger and Candida albicans. The antimicrobial results also indicate that the metal complexes are better antimicrobial agents as compared to the Schiff bases. 77-85 apm19@rediffmail.com cuatrimestre
- Published
- 2012
42. Síntesis de nopol con Sn-SBA-15 y Sn-MCM-41
- Author
-
Luis Fernando Correa, Edwin Alarcón, and Aída Luz Villa
- Subjects
Síntesis hidrotérmica ,Materials science ,Inorganic chemistry ,Formaldehído ,Sn-MCM-41 ,Chloride ,Síntesis química ,Hydrothermal circulation ,Nopol ,Catalysis ,B-pineno ,Formaldehyde ,medicine ,Sn-SBA-15 ,Chemical synthesis ,medicine.drug - Abstract
RESUMEN: Se comparó la actividad de Sn-MCM-41 y Sn-SBA-15 para la síntesis de nopol a partir de β-pineno y paraformaldehído. Los materiales se prepararon por los métodos hidrotérmico y el de impregnación húmeda incipiente, utilizando cloruro estañoso como sal precursora de Sn. Los catalizadores sintetizados por impregnación presentaron mayor actividad y fueron más selectivos a nopol que los materiales obtenidos por el método hidrotérmico. La conversión de β-pineno obtenida con Sn-MCM-41 fue similar a la obtenida con Sn-SBA-15. Mediante síntesis hidrotérmica, se obtuvo especies de Sn(IV) en forma de agregados de SnO y substituyendo isomórficamente Si en la MCM-41 y la SBA-15, respectivamente. ABSTRACT: The catalytic activity of Sn-MCM-41 and Sn-SBA-15 for nopol synthesis from β-pinene and paraformaldehyde was compared in this work. The materials were prepared by the hydrothermal and the incipient wetness impregnation methods using stannous chloride as Sn precursor. In contrast to hydrothermal methods, impregnation leads to more active and selective materials for nopol production from β-pinene. β-Pinene conversion over Sn-MCM-41 and Sn-SBA-15 was similar. In the materials obtained by hydrothermal procedures, Sn(IV) species were detected as bulk SnO in MCM-41 and 2 isomorphously substituting Si in SBA-15. COL0001941
- Published
- 2012
43. On the catalytic oxidation of ascorbic acid at self-doping polyaniline films
- Author
-
Francisco Huerta, Emilia Morallón, Carlos Sanchís, and Omar Rivero
- Subjects
chemistry.chemical_classification ,Polyaniline nanofibers ,Chemistry ,Inorganic chemistry ,General Physics and Astronomy ,Polymer ,Ascorbic acid ,Michaelis–Menten kinetics ,Catalysis ,chemistry.chemical_compound ,Catalytic oxidation ,Polyaniline ,Molecule ,Physical and Theoretical Chemistry ,QUIMICA FISICA - Abstract
Ascorbic acid molecules in either acid or conjugate base forms have been oxidized on self-doping carboxylated polyaniline thin films. The kinetic model proposed by Bartlett et al. has been successfully applied to the catalytic reactions. Active sites in the polymer have been identified as the rings having quinoid character. The existence of significant electrostatic repulsions between ionogenic groups at the self-doping polymer and negatively charged ascorbate molecules has been established thanks to the analysis of the pH dependence of the Michaelis constant. It has been found that in contrast to inorganic conductors the regeneration of active sites in polyaniline-based materials is slower at higher potentials. Such a behavior can be satisfactorily correlated with the potential dependence of the polymer electronic conductivity., Financial support from the Spanish MINECO, FEDER and Generalitat Valenciana through projects MAT2010-15273 and ACOMP/2012/133 is gratefully acknowledged. CS thanks MICINN for FPU grant and OR thanks Fundacion Carolina for predoctoral fellowship.
- Published
- 2012
44. Análisis por XPS de la formación de nitruros en un catalizador de carburo de tungsteno para la descomposición de amoníaco
- Author
-
Walter Torres Hernández
- Subjects
Hydrogen ,Carburo de Tungsteno ,Inorganic chemistry ,chemistry.chemical_element ,Descomposición de Amoníaco ,Decomposition ,Catalysis ,chemistry.chemical_compound ,Ammonia ,chemistry ,Tungsten carbide ,XPS ,Carbon nitride ,Amoníaco ,Tungsten nitride ,Syngas - Abstract
La descomposición de amoníaco es de interés actual como una fuente limpia de hidrógeno para celdas combustibles y también como un componente necesario para la limpieza del gas de síntesis producido por gasificación de la biomasa. Una publicación reciente demostró que en muestras de carburo de tungsteno pre-tratadas con mezclas de hidrogeno y monóxido de carbono, el amoníaco se descompone a 650°C sin aparente desactivación del catalizador durante 12 horas. El presente trabajo muestra el análisis por espectroscopia foto-electrónica de rayos X de los cambios composicionales que sufre la superficie del catalizador después de la reacción de descomposición. Los espectros evidencian la formación de nitruros de tungsteno, mas no de nitruros de carbono, lo cual sugiere la participación de especies WxNy como intermediarios claves en la reacción catalizada.
- Published
- 2011
45. Bioinspired fibers follow the track of natural spider silk
- Author
-
José Pérez-Rigueiro, C. Karatzas, Fernando Agulló-Rueda, Gustavo V. Guinea, Manuel Elices, C. Riekel, Gustavo R. Plaza, and Rafael Daza
- Subjects
Materials science ,Materiales ,Polymers and Plastics ,Polymer science ,Organic Chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,Crystallinity ,Ultimate tensile strength ,Polymer chemistry ,Materials Chemistry ,Spider silk ,0210 nano-technology ,Spinning - Abstract
The mechanical behavior and microstructure of bioinspired fibers spun from solutions of recombinant spidroin-like proteins were extensively characterized, and compared with those of natural spider silk fibers. It is confirmed that high performance bioinspired fibers indistinguishable from natural spider silk up to large strains can be produced through genetic engineering and conventional spinning technologies. It is also found that fibers spun from spidroin-like proteins that contain different motifs of sequence exhibit variations in their microstructure in terms of crystallinity and chain alignment, but these differences are not reflected in distinct tensile properties. This similarity in terms of their mechanical behavior indicates that bioinspired fibers are largely independent of their exact sequence of recombinant proteins and, in particular, of their proline content. Finally, it is shown that the largest differences between natural and bioinspired fibers are found at very large deformations, marking the ultimate challenge in the synthesis of silk-like fibers.
- Published
- 2011
46. Silica nanoparticles functionalised with cation coordination sites and fluorophores for the differential sensing of anions in a quencher displacement assay (QDA)
- Author
-
Mandy Hecht, José L. Vivancos, Ramón Martínez-Máñez, Félix Sancenón, Juan Soto, Pilar Calero, and Knut Rurack
- Subjects
Unclassified drug ,Pyridines ,Sulforhodamine B ,Nanoparticle ,Assay ,Photochemistry ,chemistry.chemical_compound ,QUIMICA ORGANICA ,Nickel ,Quencher displacement assay ,Materials Chemistry ,Silicon dioxide ,Fluorometry ,Pyridine derivative ,Metals and Alloys ,Particle size ,Terpyridine sulforhodamine functionalized silica nanoparticle ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Molecular recognition ,Anions ,Metal ions in aqueous solution ,Inorganic chemistry ,Anion ,Catalysis ,Fluorescence spectroscopy ,Article ,Fluorescence ,Binding site ,Cations ,Terpyridine ,PROYECTOS DE INGENIERIA ,Fluorescent Dyes ,Quenching (fluorescence) ,Rhodamines ,Ferric ion ,QUIMICA INORGANICA ,General Chemistry ,Mercury ,Cupric ion ,chemistry ,Lead ,Ceramics and Composites ,Nanoparticles ,Controlled study - Abstract
In conjunction with quenching metal ions, silica nanoparticles carrying terpyridine coordination sites and sulforhodamine B signalling units were employed for the differential fluorometric recognition of anions. © 2011 The Royal Society of Chemistry.
- Published
- 2011
47. Au@MOF-5 and Au/MOx@MOF-5 (M = Zn, Ti; x = 1, 2): Preparation and Microstructural Characterisation
- Author
-
Oleg I. Lebedev, Gustaaf Van Tendeloo, Roland A. Fischer, Maike Müller, Yuemin Wang, and Stuart Turner
- Subjects
Catalysts ,Chemistry ,Physics ,Library science ,Nanotechnology ,Metal-organic frameworks ,Inorganic Chemistry ,Host-guest systems ,Research centre ,media_common.cataloged_instance ,Nanoparticles ,Gold ,European union ,MOX fuel ,Stipend ,media_common - Abstract
[EN] The Zn-carboxylate-based porous coordination polymer MOF-5 [Zn4O(bdc)(3)] and the metal oxide loaded materials ZnO@MOF-5 and TiO2@MOF-5 were loaded in a second step with the precursor [ClAuCO] to yield intermediate materials denoted as [ClAuCO]@MOF-5, [ClAuCO]/ZnO@MOF-5 and [ClAuCO]/TiO2@MOF-5. These composites were decomposed to Au@MOF-5, Au/ZnO@MOF-5 and Au/TiO2@MOF5 under hydrogen at 100 degrees C. The nanoparticle-loaded hybrid materials were characterised by powder X-ray diffraction (PXRD), IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and N-2 sorption measurements, which reveal an intact MOF-5 structure that maintains a high specific surface area. For Au@MOF-5, crystalline Au nanoparticles were distributed over the MOF matrix in a homogeneous fashion with a size of ca. 1-3 nm, evidenced by high resolution transmission electron microscopy. In the case of Au/ZnO@MOF-5, the Au and metal oxide particles of a few nm in size were coexistent in a given volume of the MOF-5 matrix and were not separated in different crystalline MOF particles. For the TiO2 loaded materials the oxide is preferentially located near the outer surface of the MOF particles, leading to an increase of larger exterior Au particles in comparison to very small interior Au particles as observed for the other materials. Au@MOF-5, Au/ZnO@MOF-5 and Au/TiO2@MOF-5 were tested in liquid-phase oxidation of alcohols. Preliminary results show a high activity for the Au loaded materials in this reaction. This observation is attributed to the microstructure of the composites with very small Au particles distributed homogeneously over the MOF matrix., This work was supported by the Deutsche Forschungsgemeinschaft (DFG) (Research Centre "Metal Support Interaction in Heterogeneous Catalysis", SFB-558). M. M. is grateful to the Ruhr-University Research School for supporting her doctoral thesis and as well to the Evangelisches Studienwerk e. V., Villigst for a stipend. S. T. gratefully acknowledges financial support from the Fund for Scientific Research Flanders (FWO). The authors acknowledge support from the European Union (Framework 6 program under a contract from an Integrated Infrastructure Initiative, reference number 026019 ESTEEM). The authors would also like to thank M. Lieb and S. Bendix for valuable help with GC-MS analysis.
- Published
- 2011
48. Efecto de aditivos orgánicos en la deposición de catalizadores Pt-Ru
- Author
-
Marta María Elena Duarte, Juan Manuel Sieben, and C.E. Mayer
- Subjects
Recubrimientos y Películas ,Aqueous solution ,ADITIVOS ORGANICOS ,Chemistry ,Formic acid ,CATALIZADORES BIMETALICOS SOPORTADOS PT-RU ,Inorganic chemistry ,General Physics and Astronomy ,INGENIERÍAS Y TECNOLOGÍAS ,General Chemistry ,ELECTROCATALIZADORES ,Tartrate ,ELECTRODEPOSICION ,Sodium tartrate ,Catalysis ,chemistry.chemical_compound ,purl.org/becyt/ford/2 [https] ,Ingeniería de los Materiales ,Sodium citrate ,General Materials Science ,Methanol ,purl.org/becyt/ford/2.5 [https] ,Ethylene glycol - Abstract
La codeposición simultánea de Pt y Ru sobre materiales de carbono se llevó a cabo potenciostáticamente a - 0,5 V a partir de soluciones acuosas de H 2 PtCl 6 y RuCl 3 en presencia de diferentes aditivos orgánicos: 1) etilenglicol, 2) etanol, 3) ácido fórmico, 4) citrato de sodio, 5) tartrato de sodio y 6) Na 2 H 2 EDTA. El proceso de electrodeposición fue influenciado termodinámica y cinéticamente por la presencia de los diferentes agentes estabilizantes. Los análisis SEM y AFM de los ele ctrodos revelaron que el tamaño de las partículas y el área superficial activa de los catalizadores fueron notablemente afectados por la presencia de los agentes estabilizantes. Las diferencias en el comportamiento de los diferentes aditivos orgánicos en las soluciones de electrodeposición pueden ser asociadas con los siguientes efectos: 1) capacidad del estabilizante para acomplejar al ión metálico, 2) la adsorción específica de las moléculas orgánicas que inhiben el crecimiento de las partículas, y 3) la capacidad reductora de los compuestos orgánicos (sólo para los tres primeros aditivos). Los electrodos preparados con diferentes aditivos orgánicos presentan el siguiente orden decreciente de actividades catalíticas para la oxidación de metanol : citrato > tartrato > etanol > Na 2 H 2 EDTA > etilenglicol > ácido fórmico > sin estabilizante. Este comportamiento puede relacionarse con diferencias en el área superficial activa, tamaño de partícula y la estructura superficial del depósito metálico. The s imultaneous codeposition of Pt and Ru on carbon materials was carried out potentiostatically at - 0.5 V from H 2 PtCl 6 and RuCl 3 aqueous solutions in the presence of different organic additives: 1) ethylene glycol, 2) ethanol, 3) formic acid, 4) sodium citrate, 5) sodium tartrate and 6) Na 2 H 2 EDTA. The electrodeposition process was influenced thermody namically and kinetically by the stabilizers. SEM and AFM analysis of the electrodes showed that both the particle size and the active surface area were notably affected by the presence of the stabiliz ing agents . The different behaviour of the stabilizing agents may be associated with the following effects: (1) the capability of the stabilizing agent to complex the metal ions, (2) the specific adsorption of organic molecules which inhibits particle growth, and (3) the reduction capability of the organic com pounds. T he electrodes prepar ed with different organic additives exhibit the following decreasing order of activities for methanol oxidation : citrate > tartrate > ethanol > Na 2 H 2 EDTA > ethylene glycol > formic acid > without stabilizer. This comportment ca n be related to differences in the active surface area, particle size and superficial structure of the metallic deposit. Fil: Sieben, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur; Argentina Fil: Duarte, Marta María Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur; Argentina Fil: Mayer, Carlos Enrique. Universidad Nacional del Sur; Argentina
- Published
- 2010
49. Efecto del catión, del anión y del co-ión sobre la agregación de líquidos iónicos en solución acuosa
- Author
-
Alida Padrón, Jorg Thöming, José Francisco Fernández, María Rodríguez, Carlos Orbegozo, Nólides Guzmán, and Mónica Parada
- Subjects
Aqueous solution ,Chemistry ,critical micelle concentration ,Inorganic chemistry ,aggregation ,General Chemistry ,Electrolyte ,Ion ,Surface tension ,ionic liquids ,chemistry.chemical_compound ,Electrical resistivity and conductivity ,Critical micelle concentration ,Ionic liquid ,Organic chemistry ,Moiety - Abstract
The aggregation behavior of thirteen 1-alkyl-3-methylimidazolium based ionic liquids in aqueous solution is presented, considering variations of the alkyl side chain length as well as the anionic moiety. Cation and anion molecular volumes are selected as appropriate molecular descriptors. Additionally, the existing relationship between critical micelle concentration (CMC) and electrolyte concentration in solution is established, aiming to clarify ion effects. CMC values were obtained by measuring electrical conductivity and surface tension. It was confirmed that aggregation of ionic liquids in aqueous solution and in presence of inorganic salts is affected by the factors developed in this study.
- Published
- 2010
50. Effect of thiourea concentration on the electrochemical behavior of gold and copper electrodes in presence and absence of cu(ii) ions
- Author
-
A Valenzuela, Humberto Gómez, C Suárez, and H Lizama
- Subjects
Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Overpotential ,Electrochemistry ,Chloride ,Copper ,chemistry.chemical_compound ,formamidine disulfde ,Thiourea ,chemistry ,crystal quartz microbalance ,copper ,Electrode ,medicine ,electrodeposition ,Cyclic voltammetry ,Polarization (electrochemistry) ,thiourea ,medicine.drug - Abstract
The effect of thiourea (TU) concentration on copper electrodeposition was studied employing cyclic voltammetry and electrochemical crystal quartz microbalance techniques. It was found that the polarization effects are related to the type of species generated in the electrode interface. Due to formation of formamidine disulfide (FDS) at concentrations greater than 10 -4 mol dm -3 , the electrode surface is blocked, and copper electrodeposition shifts towards more negative potential values (polarizing effect). Lower concentrations favors the formation of Cu(I) -TU contributing to the de-polarization of copper electrodeposition reaction. Keywords: thiourea; electrodeposition; copper; crystal quartz microbalance; formamidine disulfide.e-mail address: hlizama@ucv.cl INTRODUCTION Combination of glue, thiourea, and chloride are used as inhibitors in nearly all copper electrorefining tankhouses 1-6 . Although numerous investigations having been conducted, the mechanism of action of these inhibitors system has not been fully clarified. It is generally accepted that the additives produce an additional local overpotential at the more active cathode sites, favoring the formation of a low roughness homogenous surface
- Published
- 2009
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.