Sample records for CATALISIS (catalysis)
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Sample records 1 - 20 shown. Select sample records:



1

Modelación de catálisis enzimática con enzimas alostéricas/ Enzymatic catalysis modelling with allosteric enzymes

Aranda, J. S.; Salgado, E.
2008-04-01

Resumen en español Las enzimas alostéricas regulan la velocidad de la reacción que catalizan en función de la concentración de un inhibidor que modifica su actividad enzimática, generando una curva de saturación sigmoidal característica. Las enzimas alostéricas son complejos enzimáticos generalmente constituidos de una subunidad catalítica y una fracción regulativa, y la actividad catalítica del complejo se establece por la cooperación entre esas subunidades enzimáticas. La si (mas) mulación realista de fenómenos biocatalíticos alostéricos depende de la modelación del comportamiento cinético de la enzima. La cinética enzimática basada en la forma cooperativa del complejo alostérico puede modelarse utilizando interacciones entre agentes. La modelación con agentes permite la representación de curvas de saturación sigmoidales, sin requerir los valores numéricos de parámetros cinéticos necesarios en otros modelos cinéticos. Datos experimentales del complejo enzimático aspartato transcarbamilasa de Escherichia coli son comparados con resultados teóricos de diferentes modelos para sistemas enzimáticos alostéricos. Los resultados de la modelación de cinética enzimática basada en agentes muestran una correlación adecuada con curvas de saturación experimentales. Resumen en inglés Allosteric enzymes control reaction rates in biochemical reactions. The catalytic activity of allosteric enzymes depends on the concentration of a certain regulating compound. A simgoidal saturation curve is a characteristic of the enzymes that exert allosteric control of reaction rates. These enzymes are rather large enzymatic complexes usually composed of at least one catalytic subunit and a regulatory fraction, and the complex catalytic activity is given by the coopera (mas) tive interactions between those enzymatic subunits. Realistic simulation of biocatalytic allosteric phenomena requires an appropiate modelling of the enzyme kinetic behavior. Modelling enzymes with cooperative kinetics can be achieved by defining interacting agents. Agent-based modelling allows an accurate representation of sigmoidal saturation curves, without the kinetic parameters that are needed in other kinetic models. Experimental data from Escherichia coli aspartate transcarbamylase are compared to theoretical results from different models for allosteric systems. Results from agent-based modelling show a good agreement with experimental saturation curves.

Scientific Electronic Library Online (Spanish)

2

Simultaneous Ultra Traces Voltammetric Determination of Platinum and Rhodium Using Adsorptive Preconcentration and Catalysis/ Determinación Simultánea de Ultratrazas de Platino y Rodio por Voltamperometría con Preconcentración Adsortiva y Catálisis

Rojas, Carlos León
2005-01-01

Resumen en español Fue evaluado un método voltamperométrico con preconcentración adsortiva y catálisis, utilizando el electrodo de gota suspendida de mercurio, para la determinación simultánea de ultratrazas de platino y rodio. Las condiciones óptimas establecidas fueron obtenidas luego de la optimización secuencial, consiguiéndose obtener una linealidad hasta los 6.00 ng/L de platino y los 0.7 ng/L de rodio. Los límites de detección y de cuantificación obtenidos son 4.0 ng/L y 10 ng/L para platino y 1.0 ng/L y 3.0 ng/L para el rodio. Resumen en inglés It was evaluated a voltammetric method with adsorptive preconcentration and catalysis, using the hanging mercury drop electrode, for the simultaneous determination of ultra traces of platinum and rhodium. The optimized conditions were obtained after the sequential optimization, obtaining linearity until 6.00 ng/L for platinum and 0.7 ng/L for rhodium. The detection and quantification limits are 4.0 ng/L and 10 ng/L for platinum and 1.0 ng/L and 3.0 ng/L for rhodium.

Scientific Electronic Library Online (Spanish)

3

Mesoporous structures having high catalytic activity in acid catalysis reactions and preparation method thereof | Estructuras mesoporosas con elevada actividad catalítica en reacciones de catálisis ácida y su procedimiento de preparación

Agúndez Rodríguez, Javier ; Díaz Carretero, Isabel ; Márquez Álvarez, Carlos ; Pérez Pariente, Joaquín

Filing Date: 2003-10-24.-- Priority Data: ES P200202509 (2002-10-31) | The invention relates to novel mesoporous aluminosilicate-type materials having a chemical composition with the following formula (in oxide moles): Al2O3: m SiO2: n M2O, wherein: m denotes a value of between 10 and 1000, preferab...

DRIVER (Spanish)

4

Producción de biodiesel de aceite crudo de palma mediante catálisis heterogénea/ Production of crude palm oil biodiesel by heterogeneous catalysis

Cardeño, Fernando; Ríos, Luis; Franco, Alexander
2010-02-01

Resumen en español Se estudió la producción de biodiesel de aceite crudo de palma mediante el uso de catalizadores heterogéneos ácidos y básicos para las etapas de preesterificación y transesterificación respectivamente. La pre-esterificación es necesaria para aceites con una acidez superior al 4% de ácidos grasos libres, ya que se evitan los problemas asociados con la formación de jabones. En ambas reacciones las variables analizadas fueron el tipo de catalizador, la temperatura (mas) y el tiempo. Se analizó la conversión del aceite a metilésteres usando cromatografía gaseosa y la estabilidad de los catalizadores mediante su reutilización. En la etapa de pre-esterificación se encontró que catalizadores ácidos del tipo resinas de poliestireno sulfonadas presentan conversiones superiores al 87% estabilidad para la esterificación de los ácidos grasos libres. Para la transesterificación se estudiaron como catalizadores heterogéneos, el carbonato de potasio libre y soportado en una matriz polimérica, obteniéndose con ambos conversiones superiores a 95 % de biodiesel; con el uso del soporte polimérico se disminuyó la velocidad de disolución de carbonato de potasio, permitiendo su reutilización hasta 10 reutilizaciones. Resumen en inglés The production of crude palm oil biodiesel was studied by using acid and basic heterogeneous catalysts by pre-esterification and transesterification steps, respectively. Pre-esterification step is necessary for high free fatty acid content oils because problems associated with soap formation are avoided. In both reactions the variables analyzed were catalyst type, temperature and time. Conversion of oil to methyl ester was analyzed using gas chromatography and the stabili (mas) ty of catalysts by means of reutilization. In the pre-esterification step it was found that acid catalysts type sulfonated polystyrene resin show high conversion and stability for the esterification of free fatty acids. Heterogeneous catalysts both free and supported in a polymeric matrix potassium carbonate were studied for transesterification. High conversions to biodiesel were obtained. Using the polymeric matrix decreased the potassium carbonate dissolution rate, allowing its reutilization.

Scientific Electronic Library Online (Spanish)

5

Variables de operación en el proceso de transesterificación de aceites vegetales: una revisión - catálisis química/ Operations variables in the transesterification process of vegetable oil: a review - chemical catalysis

Rojas González, Andrés Felipe; Girón Gallego, Erika; Torres Castañeda, Harlen Gerardo
2009-12-01

Resumen en español Este artículo presenta los resultados de una revisión bibliográfica de los efectos de las variables de operación sobre el rendimiento en la transesterificación química de aceites vegetales. Las variables estudiadas fueron: temperatura y tiempo de reacción, concentración molar alcohol:aceite vegetal, tipo de alcohol, tipo de catalizador, concentración de catalizador, intensidad del mezclado, y concentración de ácidos grasos libre y humedad. También se reporta q (mas) ue este proceso se ha llevado a cabo empleando catalizadores ácidos y básicos, a través de procesos catalíticos homogéneos y heterogéneos, para una amplia variedad de aceites. Se encontró que el rendimiento de la reacción se incrementa cuando la temperatura y el tiempo de reacción aumenta, pero disminuye a bajas concentraciones de catalizador ( 1% w/w) y humedad (> 3% w/w) en el aceite. Resumen en inglés This article describes the results of a bibliographic review of the effects of operation conditions on process yield in the chemical transesterification of vegetable oil. The parameters studied were: temperature and time reaction, alcohol:oil molar ratio, catalyst and alcohol type, catalyst concentration, mixed intensity and free fatty acid and water concentration. It also reports that this process has been carried out with basic and acid catalysts using homogeneous and h (mas) eterogeneous catalytic processes for a wide variety of oils. It was found that reaction yield increased when temperature and time reaction increased; however this parameter decreased at low catalyst concentration ( 1% w/w) and water (> 3% w/w) concentration in oil.

Scientific Electronic Library Online (Spanish)

6

SÍNTESIS DE ÓXIDOS DE SILICIO DE ALTAS ÁREA SUPERFICIAL Y POROSIDAD EMPLEANDO EL METODO SOL-GEL EN PRESENCIA DE GLICEROL Y MONOESTEARATO DE GLICERILO COMO ESTRUCTURANTES/ SYNTHESIS OF SILICON OXIDE WITH HIGH SUPERFICIAL AREA AND POROSITY THROUGH SOL-GEL TECHNIQUE USING GLYCEROL AND GLYCERYL MONOSTEARATE AS TEMPLATES

PEÑA, JUAN; CARDONA, ELIANA; RIOS, LUIS
2008-11-01

Resumen en español Este trabajo reporta una forma novedosa para la producción de óxidos de silicio (sílice) porosos mediante la técnica sol-gel usando tetraetilortosilicato (TEOS) como precursor de silicio y como orientadores de la estructura porosa glicerol (Gly) y monoestearato de glicerilo (ME), los cuales son de bajo costo y de alta disponibilidad comercial. Las sílices obtenidas presentan características porosas interesantes para una potencial aplicación en catálisis heterogén (mas) ea, como por ejemplo áreas superficiales (método BET) de alrededor de 736.3 m²/g, volumen total de poros de 0.41 cm³/g y estrecha distribución de tamaños de poro (método BJH) de aproximadamente 36 Å. Resumen en inglés This paper reports a novel synthetic route for the production of porous silicon oxides (silica) by means of the sol-gel technique using tetraethylorthosilicate (TEOS) as silicon source and glycerol (Gly) and glycerol monostearate (ME) as templates, which have low cost and wide commercial availability. The so-obtained silicas have many interesting porous characteristics for potential applications in heterogenous catalysis: specific surface area (BET method) of 736.3 m²/g, total porous volume of 0,41 cm³/g and pore size narrows distribution (BJH method) around 36 Å

Scientific Electronic Library Online (Spanish)

7

Oxidación parcial de metano a formaldehído sobre catalizadores de MoO3, Fe2O3 y ferromolibdeno/ Partial oxidation of methane to formaldehyde on MoO3, Fe2O3 and ferromolybdenum catalysts

Del Río, José Daniel; Durán, Gustavo Andrés; Orjuela Londoño, Álvaro; Sánchez, Francisco José; Guerrero Fajardo, Carlos Alberto
2007-04-01

Resumen en español Uno de los grandes retos para la catálisis ha sido la conversión directa de metano en productos químicos útiles a la industria tales como metanol y formaldehído. Actualmente el formaldehído es producido en un proceso que involucra tres pasos con gas de síntesis y metanol como productos intermedios. En este trabajo se emplearon catalizadores de MoO3, Fe2O3 y Fe2(MoO4)3 en cuatro proporciones Mo/Fe diferentes (0.5, 1, 1.5, 2). El catalizador de ferromolibdeno fue pre (mas) parado por coprecipitación. Los óxidos puros presentan mayor actividad; sin embargo, no son selectivos a formaldehído, siendo los óxidos de carbono (CO, CO2) los principales productos. Los catalizadores de ferromolibdeno mejoran la selectividad a HCHO en detrimento del grado de conversión; el contenido de molibdeno no muestra incrementos en la actividad catalítica. El aumento en la temperatura de reacción no genera un aumento en la selectividad a formaldehído. Resumen en inglés One of the main challenges for catalysis has been direct methane conversion to useful products such as methanol and formaldehyde. Formaldehyde is currently produced by a three-step industrial process with syngas and methanol as intermediate products. MoO3, Fe2O3 and Fe2(MoO4)3 catalysts were used with four different Mo/Fe molar ratios (0.5, 1, 1.5, 2) in this work. The ferromolybdenum catalyst was prepared by coprecipitation. Pure oxides are more active; however they are (mas) not formaldehyde selective, but carbon oxide (CO, CO2) selective. The ferromolybdenum catalysts showed better HCHO selectivity at low conversions; the molybdenum oxide content did not show increased in catalytic activity. Increased reaction temperature did not increase formaldehyde selectivity.

Scientific Electronic Library Online (Spanish)

8

Producción de Sílice Mesoporosa Empleando Monoestearato de Glicerol como Porógeno Oleoquímico/ Production of Mesoporous Silica using Glycerol Monostearate as Oleochemical Porogen

Peña, Juan D; Cardona, Eliana M; Marín, Juan M; Rios, Luis A
2009-01-01

Resumen en español El presente trabajo describe el desarrollo de una novedosa síntesis de sílices mesoporosas basada en un mecanismo en dos etapas en medio ácido (pH = 2), empleando materias primas renovables. La primera etapa consistió en la formación de micelas híbridas estables, producto de la interacción entre silicatos y el agente porógeno, y la segunda en la policondensación de silicatos para formar sílice. Se evaluaron dos fuentes de silicio: tetraetilortosilicato (TEOS) y (mas) metasilicato de sodio (MSiNa). Como porógeno oleoquímico se usó monoestearato de glicerol y como iniciador de la reacción de policondensación se usó fluoruro de sodio (NaF). Las sílices obtenidas con las mejores propiedades texturales, poseen características superficiales interesantes para un potencial aplicación en catálisis heterogénea, con área superficial BET de 727.4 m²/g, volumen total de poros de 0.50 cm³/g y distribución de tamaños de poro alrededor de 46.2 Å Resumen en inglés This paper describes the development of a novel synthesis of mesoporous silica based on a two-step process, in acidic media (pH = 2), using renewable raw materials. The first stage was the formation of stable hybrid micelles, product of the interaction between the porogen and silicates, and the second was the polycondensation of silicates to produce silica. Two sources of silicon were used: tetraethylortosilicate (TEOS) and sodium metasilicate (MSiNa). Glycerol monosteara (mas) te was used as oleochemical porogen and sodium fluoride was used as initiator for the reaction of condensation of silica. The silica obtained with the best textural properties have interesting surface characteristics for potential applications in heterogeneous catalysis, with BET surface area of 727.4 m² / g, total volume of pores of 0.50 cm³/g and pore size distribution of about 46.2 Å

Scientific Electronic Library Online (Spanish)

9

Electrochemical chlorination of phenylnonane

Fernández, Lenys; Márquez, Olga P; Márquez, Jairo; Velásquez, William
2002-08-01

Resumen en español Usando la técnica de catálisis de transferencia entre fases, se reporta la cloración anódica del fenilnonano en un sistema de dos líquidos inmiscibles (diclorometano-agua) utilizando iones de tetrabutilamonio como agente de transferencia entre fases del ion cloruro. Se obtuvo como producto principal el pclorononilbenceno, con un rendimiento (47%) mayor al obtenido de las electrólisis en un medio orgánico sencillo (24%). La formación de este producto es dependiente (mas) del tipo y concentración del agente de transferencia, pH, temperatura y potencial de oxidación. Los valores óptimos obtenidos fueron: Bu4NHSO4 (0.3 M), pH: 4 - 6, t = 35°C, E = 1.70 V vs Ag/Ag+. De acuerdo a nuestros resultados, a potenciales de oxidación menores que el del aromático, la formación del producto clorado se debe a la reacción química de la especie clorante generada electroquímicamente y el fenilnonano en solución mientras que a potenciales mayores, la reacción ocurre entre la especie clorante y una especie catiónica proveniente de la electrooxidación del fenilnonano. Experimentos realizados en un medio acetonitrilo-agua confirman estas propuestas de reacción; en este caso a bajos potenciales (1.40 V) se forma el p-clorononilbenceno (20%) por reacción de especies clorante-fenilnonano, mientras que a potenciales mayores se obtienen p-clorononilbenceno (27%) y nonilacetanilida (34%) por reacción de la especie clorante y el medio electrolítico con la especie catiónica intermediaria orgánica. Resumen en inglés By using phase transference catalysis, anodic chlorination of phenylnonane in a two immiscible liquids (dichloromethane-water) with tetrabutylammonium as the transference agent; pchlorononylbenzene was obtained as the main product with an organic yield of 47%, which means an improvement compared with 24% obtained when using a single solvent. Formation of p-chlorononylbenzene depends upon the nature and concentration of the transference agent, pH, temperature, and oxidatio (mas) n potential. The best conditions were reached using 0.3M Bu4NHSO4, at a pH ranging within 4 and 6, at 35°C and 1.70 V vs Ag/Ag+. Our results suggest that at those potentials below the oxidation peak of the aromatic, the formation of the chlorinated species is due to a chemical reaction between the electrochemically generated chlorinating species and the neutral molecule of phenylnonane. On the other hand, at those potentials above the oxidation peak, the reaction occurs between the chlorinating species and a cationic species generated by oxidation of phenylnonane. To confirm our results, experiments were run in acetonitrile-water, showing that at low potentials (~1.40 V vs Ag/Ag+), 20% of p-chlorononylbenzene is formed by direct reaction between the chlorinating species and the phenylnonane while at higher potentials, 27% of p-chlorononylbenzene and 34% of nonylacetamide is produced by reaction of the chlorinating species and the electrolytic medium with the organic cationic intermediate species.

Scientific Electronic Library Online (Spanish)

10

Los procesos de glucosilación no enzimática/ The nonenzymatic glycosylation processes

Aponte Ramírez, Liudmila; Ramírez Zayas, Roger; Hernández González, Silvia; Somontes Zamora, Dariel
2009-12-01

Resumen en español Se realizó una revisión bibliográfica con el objetivo de actualizar los conocimientos sobre el proceso de glucosilación no enzimática. Su importancia fisiológica se puso de manifiesto a partir del hallazgo de que parte de la hemoglobina en la sangre de individuos sanos está glucosilada y que el nivel de glucosilación es mayor en pacientes diabéticos. La colágeno fue la primer proteína donde se demostró la existencia de enlaces intermoleculares covalentes produ (mas) cidos por este mecanismo en la base molecular de la glomerulopatía y retinopatía diabética. La disminución de la actividad biológica como consecuencia de la glucosilación aparece en un reducido número de pacientes, incluyendo varios sistemas enzimáticos donde grupos amino participaron en la catálisis enzimática. La activación de receptores por la unión de proteínas con los productos de glucosilación avanzada estimula la producción en macrófagos, células endoteliales y mesangiales de factores de crecimiento y mecanismos procoagulantes que favorecen la formación de trombos en los sitios de acumulación extracelular de estos compuestos, la oclusión de vasos, hipoxia y necrosis tisular. Las reacciones en las que intervienen radicales libres, participan en la formación de los productos de glucosilación avanzada provocando su unión de manera covalente e irreversible a las proteínas favoreciendo la ateroesclerosis. En la Diabetes la hemoglobina glucosilada y la fructosamina son las determinaciones de laboratorio más frecuentes utilizadas en el control metabólico y su estabilidad, que permite prevenir los efectos nocivos de la hiperglucemia. Resumen en inglés A bibliographical revision with the objective to bring-up-to date the knowledge on the nonenzymatic glycosylation process was carried out. Its physiologic importance was shown, starting from the discovery that a part of the hemoglobin in blood of healthy individuals is glycosylated and the glycosylation level is bigger in diabetic patients. The collagen was the first protein where the existence of covalent intermolecular bonds was demonstrated produced by this mechanism i (mas) n the molecular basis of the glomerulopathy and diabetic retinopathy. The decrease of the biological activity as consequence of glycosylation appears in a reduced number of patients, including several enzymatic systems where amino groups participated in the enzymatic catalysis. The receptors´activation for proteins union with products of advanced glycosylation stimulates the production in macrophages, endothelial and mesangial cells of growth factors and procoagulant mechanisms that favor the thrombus formation in the places of extracellular accumulation of these compounds, the occlusion of vessels, hypoxia and tissular necrosis. Reactions in which intervene free radicals, participate in the formation of the advanced glycosylation products causing its union in covalent and irreversible way to the proteins favoring atherosclerosis. In diabetes the glycosylated hemoglobin and the fructosemia are the most frequent laboratory determinations used in the metabolic control and its stability allow us to prevent the noxious effects of hyperglycemia.

Scientific Electronic Library Online (Spanish)

12

The solvent effect in the hydrogenation of citral over Ir and Ir-Fe/TiO2 catalysis

Rojas, H. ; García Fierro, José Luis ; Reyes, P.

The solvent effect in the citral hydrogenation over iridium catalysts has been studied. The catalysts used in this research were, the monometallic Ir/ TiO2 reduced at low or high temperature (LT y HT) and the bimetallic Ir-Fe/TiO2 (LT y HT) catalysts. As solvent n-heptane, an equimolar mixture n-hep...

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14

The selective reduction of NOx with propene on Pt-beta catalyst: a transient study

García Cortés, Jorge Manuel; Illán Gómez, María José; Salinas Martínez de Lecea, Concepción

The mechanism of the NO/C3H6/O2 reaction has been studied on a Pt-beta catalyst using transient analysis techniques. This work has been designed to provide answers to the volcano-type activity behaviour of the catalytic system, for that reason, steady state transient switch (C3H6/NO/O2 → C3H6/Ar/O2,...

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15

The crystal structure of an eukaryotic iron superoxide dismutase suggests intersubunit cooperation during catalysis

Muñoz, Inés G. ; Morán, José F. ; Becana Ausejo, Manuel ; Montoya, Guillermo

The definitive version is available at:http://www.proteinscience.org/http://www3.interscience.wiley.com/journal/121502357/homeThis article is open access through PubMed Central. | Superoxide dismutases (SODs) are a family of metalloenzymes that catalyze the dismutation of superoxide anion rad...

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16

The crystal structure of an eukaryotic iron superoxide dismutase suggests intersubunit cooperation during catalysis

Muñoz, Inés G.; Morán, José F.; Becana Ausejo, Manuel; Montoya, Guillermo
2005-02-01

Digital.CSIC (Spain)

18

Textural characterisation of activated carbons obtained from poly(ethylene terephthalate) by carbon dioxide activation

Parra Soto, José Bernardo ; Ovín Ania, M.ª Concepción ; Arenillas de la Puente, Ana ; Pis Martínez, José Juan

7 pages.-- Issue title: Characterization of Porous Solids VI, Proceedings of the 6th International Symposium on the Characterization of Porous Solids (COPS-VI). | Polymer waste nowadays accounts for a large part of municipal solid waste and so poses a problem of considerable concern for the environm...

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19

Textural characterisation of activated carbons obtained from poly(ethylene terephthalate) by carbon dioxide activation

Parra Soto, José Bernardo; Ovín Ania, M.ª Concepción; Arenillas de la Puente, Ana; Pis Martínez, José Juan
2002-01-01

Digital.CSIC (Spain)

20

Templated synthesis of nanosized mesoporous carbons

Álvarez García, Sonia; Valdés-Solís Iglesias, Teresa; Fuertes Arias, Antonio Benito
2008-07-01

Digital.CSIC (Spain)

21

Template-controlled acidity and catalytic activity of ferrierite crystals

Pinar Prieto, Ana B. ; Márquez-Álvarez, C. ; Grande-Casas, M. ; Pérez-Pariente, J.

A synthesis strategy to tailor the acid sites location in ferrierite crystals has been developed. The zeolite catalysts were synthesised in fluoride medium using different combinations of organic structure directing agents (SDAs) in the absence of inorganic cations. Therefore, the negative charge as...

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22

Template-controlled acidity and catalytic activity of ferrierite crystals

Pinar, Ana Belén; Márquez Álvarez, Carlos; Grande Casas, María Sol; Pérez Pariente, Joaquín
2009-03-06

Digital.CSIC (Spain)

23

Synthesis, Characterization and Catalytic Applications of Organized Mesoporous Aluminas

Márquez-Alvarez, C.; Zilková, N.; Pérez-Pariente, J.; Čejka, J.
2008-04-02

Digital.CSIC (Spain)

24

Synthesis of prolines by enantioselective 1,3-dipolar cycloaddition of azomethine ylides and alkenes catalyzed by chiral phosphoramidite-silver(I) complexes

Nájera Domingo, Carmen; Retamosa Hernández, María de Gracia; Martín Rodríguez, María; Sansano Gil, José Miguel

The endo-diastereo- and enantioselective 1,3-dipolar cycloaddition of azomethine ylides and electrophilic alkenes is efficiently catalysed by chiral phosphoramidite-silver(I) perchlorate complexes. The reaction allows the presence of different types of substituents in the 1,3-dipole and can be appli...

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25

Synthesis of polymer bound azabis(oxazoline) ligands and their application in asymmetric cyclopropanations.

Werner, Heiko; Herrerías, Clara I.; Glos, Michael; Gissibl, Anja; Fraile, José M.; Pérez, Ignacio; Mayoral, José A.; Reiser, Oliver
2006-01-19

Digital.CSIC (Spain)

26

Synthesis of p-cymene from limonene, a renewable feedstock

Martin-Luengo, M. A. ; Yates, M. ; Martinez Domingo, M. J. ; Casal, B. ; Iglesias, M. ; Esteban, M. ; Ruíz Hitzky, Eduardo

Highly selective limonene conversions to p-cymene in short reaction times were achieved under ‘‘solvent free’’ conditions over mesoporoussilica–alumina supports heated by microwave irradiation. An increase in the silica content of these mixed oxides led to increases in the specificsurface area, po...

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27

Synthesis of p-cymene from limonene, a renewable feedstock

Martin-Luengo, M. A.; Yates, M.; Martínez Domingo, M. J.; Casal, B.; Iglesias, M.; Esteban, M.; Ruiz Hitzky, Eduardo
2008-01-01

Digital.CSIC (Spain)

28

Synthesis of all-silica and high-silica molecular sieves in fluoride media

Camblor, Miguel Ángel ; Villaescusa, Luis A. ; Díaz Cabañas, María José

Recent advances in the synthesis of all-silica and high-silica crystalline molecular sieves in fluoride media, with special regard to low framework density phases, are presented. The fundamental differences between the synthesis in hydroxide and fluoride media with respect to the properties of the ...

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29

Synthesis of all-silica and high-silica molecular sieves in fluoride media

Camblor, Miguel Ángel; Villaescusa, Luis A.; Díaz Cabañas, María José
1999-01-01

Digital.CSIC (Spain)

30

Synthesis and structure of chiral-at-metal complexes with the ligand (S)-2-[(Sp)-2-(diphenylphosphino)ferrocenyl]-4-isopropyloxazoline

Carmona, Daniel; Medrano, Roberto; Dobrinovich, Isabel T.; Lahoz, Fernando J.; Ferrer, Joaquina; Oro, Luis A.
2006-12-15

Digital.CSIC (Spain)

33

Substrate channelling in an engineered bifunctional aldolase/kinase enzyme confers catalytic advantage for C–C bond formation

Iturrate Montoya, Laura; Sánchez-Moreno, Israel; Doyagüez, Elisa G.; García-Junceda, Eduardo; RSC Publishing
2010-02-11

Digital.CSIC (Spain)

34

Structural changes in polyethylene terephthalate (PET) wastes materials caused by pyrolysis and CO2 activation

Parra Soto, José Bernardo ; Ovín Ania, M.ª Concepción ; Arenillas de la Puente, Ana ; Rubiera González, Fernando

11 pages. | For ecological reasons, there is an increasing demand for recycling polyethylene terephthalate (PET) wastes in developed countries. Although one potential application might be its utilisation for the production of activated carbons, the behaviour of these wastes when subjected to differe...

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35

Structural changes in polyethylene terephthalate (PET) wastes materials caused by pyrolysis and CO2 activation

Parra Soto, José Bernardo; Ovín Ania, M.ª Concepción; Arenillas de la Puente, Ana; Rubiera González, Fernando; Pis Martínez, José Juan; Palacios, J. M.
2006-06-01

Digital.CSIC (Spain)

38

Solvent-free synthesis of racemic α-aminonitriles

Baeza Carratalá, Alejandro; Nájera Domingo, Carmen; Sansano Gil, José Miguel

A very simple one-step, environmentally friendly procedure for the synthesis of α-aminonitriles from aldehydes and ketones, using trimethylsilyl cyanide in the absence of solvent, is reported. The active catalyst of this three-component (Strecker) reaction was the amine employed in the transformatio...

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39

Solid catalysts for the synthesis of fatty esters of glycerol, polyglycerols and sorbitol from renewable resources

Carlos Márquez Alvarez, Carlos

Partial esters of polyols such as glycerol, polyglycerols and sorbitol are nonionicsurfactants used as emulsifiers in the food, detergents and cosmetics industries.The commercial large-scale production of these chemicals relies on traditionalhomogeneous catalysis processes making use of strong mi...

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41

Silylation of titanium-containing amorphous silica catalyst: Effect on the alkenes epoxidation with H2O2

Capel-Sanchez, M. Carmen; Campos-Martin, Jose M.; Fierro, Jose L. G.
2010-01-01

Digital.CSIC (Spain)

43

Role of electron-hole pair excitations in the dissociative adsorption of diatomic molecules on metal surfaces

Juaristi Oliden, Joseba Iñaki ; Alducin Ochoa, Maite ; Díez Muiño, Ricardo ; Busnengo, Heriberto Fabio

PACS nts.: 82.65.+r, 34.35.+a, 68.49.Df, 82.20.Kh. | We quantitatively evaluate the contribution of electron-hole pair excitations to the reactive dynamics of H2 on Cu(110) and N2 on W(110), including the six dimensionality of the process in the entire calculation. The interaction energy between mol...

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44

Role of electron-hole pair excitations in the dissociative adsorption of diatomic molecules on metal surfaces

Juaristi Oliden, Joseba Iñaki; Alducin Ochoa, Maite; Díez Muiño, Ricardo; Busnengo, Heriberto Fabio; Salin, Antoine
2008-03-20

Digital.CSIC (Spain)

45

Ring Expansion versus Cyclization in 4-Oxoazetidine-2- carbaldehydes Catalyzed by Molecular Iodine: Experimental and Theoretical Study in Concert

Alcaide, Benito; Almendros, Pedro; Cabrero, Gema; Callejo, Ricardo; Ruiz, M. Pilar; Arnó, Manuel; Domingo, Luis R.
2010-07-01

Digital.CSIC (Spain)

46

QM/MM Modeling of enantioselective pybox-ruthenium- and box-copper-catalyzed cyclopropanation reactions: Scope, performance, and applications to ligand design

García, José I.; Jiménez-Osés, Gonzalo; Martínez-Merino, Víctor; Mayoral, José A.; Pires, Elísabet; Villalba, Isabel
2007-02-01

Digital.CSIC (Spain)

47

Protein radicals in fungal versatile peroxidase: Catalytic tryptophan radical in both Compound-I and Compound-II and studies on W164Y, W164H and W164S variants

Ruiz-Dueñas, Francisco J.; Pogni, Rebecca; Morales, María; Giansanti, Stefania; Mate, María J.; Romero, Antonio; Martínez Hernández, María Jesús; Basosi, Riccardo; Martínez Ferrer, Ángel Tomás
2009-01-21

Digital.CSIC (Spain)

48

Protein flexibility and metal coordination changes in DHAP-dependent aldolases

Jiménez, Aurora; Clapés Saborit, Pere; Crehuet, Ramón
2009-01-26

Digital.CSIC (Spain)

49

Preparation of Ni-doped carbon nanospheres with different surface chemistry and controlled pore structure

Zubizarreta, Leire ; Arenillas de la Puente, Ana ; Pis Martínez, José Juan

8 pages, 9 figures, 2 tables.-- Available online on Dec 27, 2007. | In classic carbon supports is very difficult to control pore size, pore size distribution, and surface chemical properties at the same time. In this work microporous carbons derived from furfuryl alcohol are used as support to prepa...

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50

Preparation of Ni-doped carbon nanospheres with different surface chemistry and controlled pore structure

Zubizarreta, Leire; Arenillas de la Puente, Ana; Pis Martínez, José Juan
2008-04-30

Digital.CSIC (Spain)

51
52

Photocatalytic-based strategies for H2S elimination

Portela, R.; Suárez, S.; Rasmussen, S.B.
2010-01-01

Digital.CSIC (Spain)

54

Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home-prepared titanium dioxide: 1. Selectivity enhancement by aliphatic alcohols

Augugliaro, Vincenzo; Kisch, Horst; Loddo, Vittorio; López-Muñoz, María José; Márquez-Alvarez, Carlos; Palmisano, Giovanni; Palmisano, Leonardo; Parrino, Francesco; Yurdakal, Sedat
2008-10-31

Digital.CSIC (Spain)

55

Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home prepared titanium dioxide: 2. Intrinsic and surface features of catalysts

Augugliaro, Vincenzo; Kisch, Horst; Loddo, Vittorio; López-Muñoz, María José; Márquez-Álvarez, Carlos; Palmisano, Giovanni; Palmisano, Leonardo; Parrino, Francesco; Yurdakal, Sedat
2008-10-31

Digital.CSIC (Spain)

56
58

Oxidative processes of desulfurization of liquid

Campos Martín, Jose Miguel; Capel-Sanchez, M. Carmen; Perez Presas, Patricia; Fierro, Jose L. G.
2010-01-01

Digital.CSIC (Spain)

59

On the mechanism of reactive adsorption of dibenzothiophene on organic waste derived carbons

Ovín Ania, M.ª Concepción ; Parra Soto, José Bernardo ; Arenillas de la Puente, Ana ; Rubiera González, Fernando

5 pages, 4 figures, 3 tables.-- Available online Dec 27, 2006. | Issue title: Sixth International Symposium on Effects of surface heterogeneity in adsorption and catalysis on solids - ISSHAC-VI (Zakopane, Poland, Aug 28-Sep 2, 2006). | The mechanism of reactive adsorption of dibenzothiophene (DBT) o...

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60

On the mechanism of reactive adsorption of dibenzothiophene on organic waste derived carbons

Ovín Ania, M.ª Concepción; Parra Soto, José Bernardo; Arenillas de la Puente, Ana; Rubiera González, Fernando; Bandosz, T. J.; Pis Martínez, José Juan
2007-04-30

Digital.CSIC (Spain)

61

Nucleation and growth of manganese oxides on metallic surfaces as a tool to prepare metallic monoliths

Frías, D. M. ; Nousir, S. ; Barrio, I. ; Montes, M. ; Martínez, L. M. ; Centeno Gallego, Miguel Ángel ; Odriozola Gordon, José Antonio

8 p. | The use of austenitic stainless steel (AISI 304) as metallic substrate for catalytic devices is explored in this work as well as an alternative procedure to the washcoating of the active phase. Catalyst deposition on austenitic stainless steel takes advantage of the manganese concentration of...

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62

Nucleation and growth of manganese oxides on metallic surfaces as a tool to prepare metallic monoliths

Frías, D. M.; Nousir, S.; Barrio, I.; Montes, M.; Martínez, L. M.; Centeno Gallego, Miguel Ángel; Odriozola Gordon, José Antonio
2007-06-15

Digital.CSIC (Spain)

63

Nonafluorobutanesulfonyl Azide: A Shelf-Stable Diazo Transfer Reagent for the Synthesis of Azides from Primary Amines

Suárez, José Ramón; Trastoy, Beatriz; Pérez-Ojeda, M. Eugenia; Marín-Barrios, Rubén; Chiara, José Luis
2010-01-01

Digital.CSIC (Spain)

64

Noble-free potassium-bimetallic catalysts supported on beta-zeolite for the simultaneous removal of NOx and soot from simulated diesel exhaust

Nejar, Najlae; Illán Gómez, María José

This paper deals with the activity of the KCu and KCo catalysts supported on beta-zeolite for the simultaneous NOx/soot removal from asimulated diesel exhaust, containing C3H6 as model hydrocarbon. In order to reveal the effect of potassium, the corresponding monometalliccatalysts (Co/beta and Cu/...

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65

Nitrate removal using natural clays modified by acid thermoactivation

Mena-Durán, C. J.; Sun Kou, M. R.; López, T.; Azamar-Barrios, J. A.; Aguilar, D. H.; Domínguez, M. I.; Odriozola Gordon, José Antonio
2007-01-05

Digital.CSIC (Spain)

66

Nickel nanoparticles in hydrogen-transfer reductions: characterisation and nature of the catalyst

Alonso Valdés, Francisco; Riente Paiva, Paola; Sirvent Pérez, Juan Alberto; Yus Astiz, Miguel

Nickel nanoparticles, readily prepared by reduction of nickel(II) chloride with lithium and a catalytic amount of DTBB, have been used in the transfer hydrogenation of carbonyl compounds and have been fully characterised by different means. The reaction rate of the transfer hydrogenation was found t...

DRIVER (Spanish)

67

Multipurpose box- and azabox-based immobilized chiral catalysts

Fraile, José M.; Pérez, Ignacio; Mayoral, José A.; Reiser, Oliver
2006-08-11

Digital.CSIC (Spain)

68

Molecular photoreactivity on metal-oxide surfaces from first-principles: photocathalysis and photovoltaics

Lara Castells, M. Pilar de; Aguirre Castiblanco, Néstor Fabián; López Durán, David; Ortega Mateo, José; Mitrushchenkov, Alexander O.
2010-02-01

Digital.CSIC (Spain)

69

Method for the dry dispersion of nanoparticles and the production of hierarchical structures and coatings

Fernández Lozano, José Francisco; Lorite, Israel; Rubio Marcos, Fernando; Romero Fanego, Juan José; García García-Tuñón, Miguel Ángel; Quesada, Adrián; Martín-González, Marisol S.; Costa Krämer, José Luis
2010-01-28

Digital.CSIC (Spain)

70

Metal complexes versus organocatalysts in asymmetric 1,3-dipolar cycloadditions

Nájera Domingo, Carmen; Sansano Gil, José Miguel; Yus Astiz, Miguel

In this review, a comparison between the Lewis acid catalysed and organocatalysed 1,3-dipolar cycloaddition is presented with special focus on the enantioselective synthesis of five-membered hetero- or carbocyclic systems, is described. These reactions exhibit very interesting features, but the most...

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71

Mesoporous structures having high catalytic activity in acid catalysis reactions and preparation method thereof

Agúndez Rodríguez, Javier; Díaz Carretero, Isabel; Márquez Álvarez, Carlos; Pérez Pariente, Joaquín; Sastre de Andrés, Enrique
2004-05-13

Digital.CSIC (Spain)

72

Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst

Valdés-Solís Iglesias, Teresa ; Valle Vigón, Patricia ; Álvarez García, Sonia ; Marbán Calzón, Gregorio

6 pages, 5 figures. -- Printed version published Dec 2007. -- Correction published in Catalysis Communications 9(15): 2621 (2008), http://hdl.handle.net/10261/11596 | Spinel ferrite MnFe2O4 nanoparticles were synthesized by means of a nanocasting technique using a low-cost mesoporous silica gel as a...

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73

Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst

Valdés-Solís Iglesias, Teresa; Valle Vigón, Patricia; Álvarez García, Sonia; Marbán Calzón, Gregorio; Fuertes Arias, Antonio Benito
2007-04-10

Digital.CSIC (Spain)

74

Machine for the controlled reproduction of the pressure, temperature and irradiation conditions of planetary atmospheres or terrestrial environments and method of using said machine

Martín Gago, José Ángel; Gómez Elvira, Javier; Mateo Martí, Eva; Prieto Ballesteros, Olga; Sobrado Vallecillo, Jesús Manuel
2007-05-03

Digital.CSIC (Spain)

75

Liquid-Phase Oxidation of p-Xylene using N-Hydroxyimides

Falcon, Horacio; Campos-Martin, Jose M.; Al-Zahrani, Saeed M.; Fierro, Jose L. G.
2010-01-01

Digital.CSIC (Spain)

76

Interactions between gemini surfactants and polymers: thermodynamic studies

Muzzalupo, Rita; Infante, María Rosa; Pérez, Lourdes; Pinazo Gassol, Aurora; Marqués, Eduardo F.; Antonelli, Marta Letizia; Strinati, Chiara; La Mesa, Camillo
2007-04-19

Digital.CSIC (Spain)

77

Iniciativas institucionales e individuales en la creación de estructuras científicas: el Instituto de Tecnología Química

Castro Martínez, Elena ; Fernández de Lucio, Ignacio

17 pages, 3 figures, 1 table. | [ES] Se analiza la evolución del Instituto de Tecnología Química (ITQ), centro mixto del Consejo Superior de Investigaciones Científicas y de la Universidad Politécnica de Valencia, desde su creación en 1990 en el marco de una iniciativa de colaboración institucional ...

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80

Improved bacteria detection by coupling magneto-immunocapture and amperometry at flow-channel microband electrodes

Laczka, Olivier; Maesa, José María; Godino, Neus; del Campo, Javier; Fougt-Hansen, Mikkel; Kutter, Jörg P.; Snakenborg, Detlef; Muñoz-Pascual, Francesc-Xavier; Baldrich, Eva
2011-02-23

Digital.CSIC (Spain)

81

Immobilisation of fructosyltransferase from Aspergillus aculeatus on epoxy-activated Sepabeads EC for the synthesis of fructo-oligosaccharides

Ghazi, Iraj ; Gómez de Segura, Aránzazu ; Fernández-Arrojo, Lucía ; Alcalde, Miguel ; Yates, Malcolm ; Rojas-Cervantes, M. Luisa

9 pages, 7 figures.-- Printed version published Aug 1, 2005. | The transfructosylating activity present in two commercial pectinase preparations (Pectinex Ultra SP-L, from Aspergillus aculeatus, and Rapidase TF, from Aspergillus niger) was studied. Pectinex Ultra SP-L, which has a high transferase/h...

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82

Immobilisation of fructosyltransferase from Aspergillus aculeatus on epoxy-activated Sepabeads EC for the synthesis of fructo-oligosaccharides

Ghazi, Iraj; Gómez de Segura, María Aránzazu; Fernández-Arrojo, Lucía; Alcalde Galeote, Miguel; Yates Buxcey, Malcolm; Rojas-Cervantes, M. Luisa; Plou Gasca, Francisco José; Ballesteros, Antonio
2005-06-01

Digital.CSIC (Spain)

83

Hydrothermal preparation of highly photoactive TiO2 nanoparticles

Hidalgo López, María del Carmen ; Aguilar, M. ; Maicu, M. ; Navío, José Antonio ; Colón Ibáñez, Gerardo

TiO2 nanoparticles have been prepared by amine assisted sol–gel precipitation of Ti4+ aqueous solutions and further hydrothermal treatment.The effect of different starting acidic solution (nitric, chlorhydric and acetic acids) as well as the addition of triethylamine (TEA) at different pH hasbeen ...

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84

Hydrothermal preparation of highly photoactive TiO2 nanoparticles

Hidalgo López, María del Carmen; Aguilar, M.; Maicu, M.; Navío, José Antonio; Colón Ibáñez, Gerardo
2007-01-01

Digital.CSIC (Spain)

85

Highly efficient deep desulfurization of fuels by chemical oxidation

Capel Sánchez, María del Carmen; Perez-Presas, P.; Campos Martín, Jose Miguel; Fierro, Jose L. G.
2010-01-01

Digital.CSIC (Spain)

86
88

Gold-catalyzed benzylic CH activation at room temperature

Hashmi, A. Stephen K.; Schäfer, Sascha; Wölfle, Michael; Diez Gil, Cesar; Fischer, Peter; Laguna, Antonio; Blanco, M. Carmen; Gimeno, M. Concepción
2007-07-01

Digital.CSIC (Spain)

89

Gold-Catalyzed [4C+3C] Intramolecular Cycloaddition of Allenedienes: Synthetic Potential and Mechanistic Implications

Trillo, Beatriz; López, Fernando; Montserrat, Sergi; Ujaque, Gregori; Castedo, Luis; Lledós, Agustí; Mascareñas, José L.
2009-02-19

Digital.CSIC (Spain)

90

Gold-Catalyzed Synthesis of Aromatic Azo Compounds from Anilines and Nitroaromatics

Grirrane, Abdessamad ; Corma, Avelino ; García Gómez, Hermenegildo

4 pages.-- Supplementary material available at the publisher's site: Materials and methods, figs S1-S3, table S1. | Final version of the paper available at: http://dx.doi.org/10.1126/science.1166401 | The selective formation of aromatic azo compounds at preparative or industrial levels requires stoi...

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91

Gold-Catalyzed Synthesis of Aromatic Azo Compounds from Anilines and Nitroaromatics

Grirrane, Abdessamad; Corma, Avelino; García Gómez, Hermenegildo
2008-12-12

Digital.CSIC (Spain)

93

Formation of multiwalled carbon nanotube-Pd nanoparticle nanocomposites: influence of the reaction media and applications on catalyzed C-C coupling

Cano, Manoli ; Benito, Ana M. ; Maser, Wolfgang K. ; Urriolabeitia, Esteban P.

2 pages, 1 figure, 1 table.-- Contributed to: Carbon 2009 (Biarritz, France, Jun 14-19, 2009). | Palladium nanoparticles were prepared using different methods in conventional organic solvents and in ionic liquids. The deposition of these Pd nanoparticles onto multiwalled carbon nanotubes produces ho...

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95

Force-clamp spectroscopy detects residue co-evolution in enzyme catalysis.

Pérez-Jímenez, Raul; Kosuri, Pallav; Rodríguez-Larrea, David; Gavira Gallardo, J. A.; Fernández, Julio M.; Sánchez-Ruiz, José M.; Wiita, Arun P.
2008-10-03

Digital.CSIC (Spain)

96

Fluorous phosphine-assisted recycling of gold catalysts for hydrosilylation of aldehydes

Lantos, Diana; Contel, María; Larrea Arbáizar, Ángel; Szabó, Dénes; Horváth, István T.
2006-07-01

Digital.CSIC (Spain)

97

Fischer-Tropsch synthesis on mono- and bimetallic Co and Fe catalysts in fixed-bed and slurry reactors

Peña O'Shea, Víctor A. de la ; Álvarez-Galván, M.ª Consuelo ; Campos Martín, José Miguel ; García Fierro, José Luis

9 pages, 9 figures.-- Printed version published on Jun 30, 2007. | Mono- and bimetallic cobalt and iron oxide nanoparticles deposited on the surface of a silica substrate were tested in a fixed-bed reactor and stirred-tank slurry reactor under different process conditions, for the Fischer–Tropsch re...

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98

Fischer-Tropsch synthesis on mono- and bimetallic Co and Fe catalysts in fixed-bed and slurry reactors

Peña O'Shea, Víctor A. de la; Álvarez Galván, María Consuelo; Campos Martín, Jose Miguel; García Fierro, José Luis
2007-04-06

Digital.CSIC (Spain)

100

Exploiting [2+2] cycloaddition chemistry: achievements with allenes

Alcaide, Benito; Almendros, Pedro; Arangocillo, Cristina
2010-01-01

Digital.CSIC (Spain)

101

Evidence of zeolitic-like domains in mesostructured aluminosilicates: FTIR spectroscopy of basic probe molecules

Sánchez, M.T.; Agúndez, J.; Pérez-Pariente, J.; Márquez-Alvarez, C.; Onida, B.; Garrone, E.
2007-07-01

Digital.CSIC (Spain)

102

Ethylbenzene Oxidation to its Hydroperoxide in the presence of N Hydroxyimides and Minute Amounts of Sodium Hydroxide

Toribio, Pedro P. ; Gimeno-Gargallo, Ana ; Capel-Sanchez, M. Carmen ; de Frutos, M. Pilar ; Campos-Martin, Jose M.

N-hydroxyimides of the type N-hydroxyphthalimide (NHPI), N-hydroxysuccinimide(NHSI), N-hydroxymaleinimide (NHMI) and N-hydroxynaphthalimide (NHNI) wereused in ethylbenzene oxidation with air under soft reaction conditions. Theethylbenzene conversion profile was found to increase almost linearly w...

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103

Ethylbenzene Oxidation to its Hydroperoxide in the presence of N Hydroxyimides and Minute Amounts of Sodium Hydroxide

Toribio Temprado, Pedro Pablo; Gimeno-Gargallo, Ana; Capel Sánchez, María del Carmen; de Frutos, M. Pilar; Campos Martín, Jose Miguel; Fierro, Jose L. G.
2009-01-01

Digital.CSIC (Spain)

104

Estabilidad de vitaminas en nutrición parenteral/ Vitamins stability in parenteral nutrition

Such Díaz, A.; Sánchez Gil, C.; Gomis Muñoz, P.; Herreros de Tejada, A.
2009-02-01

Resumen en español Objetivo: Hace algunas décadas se publicaron varios estudios describiendo la degradación de vitaminas en nutrición parenteral (NP) y su catalización por oligoelementos tales como el cobre. Por ello se instauró la práctica de administrar oligoelementos y vitaminas a días alternos y aditivarlos el mismo día de la administración. Todavía muchos hospitales españoles siguen estas recomendaciones aunque actualmente se utilizan productos, tipo de material del envase y (mas) formas de administración distintas de las de entonces. El objetivo de esta revisión es determinar si en las condiciones actuales de preparación y administración de NP sería recomendable la administración conjunta de vitaminas y oligoelementos y cuantos días serían estables en refrigeración antes de su administración. Ámbito: Se han revisado los artículos sobre estabilidad de vitaminas en NP publicados posteriormente a 1990. Resultados: Con la vitamina A hay resultados contradictorios pero la administración "todo en uno" y la fotoprotección disminuyen considerablemente su degradación y parece que no existen diferencias entre añadir la vitamina antes de su administración o hacerlo con anterioridad. La vitamina E se muestra estable con fotoprotección durante 3-7 días en refrigeración más un día a temperatura ambiente. La vitamina C es estable junto a oligoelementos en bolsas multicapa por 2-7 días en refrigeración más un día a temperatura ambiente. La tiamina es estable si se utilizan soluciones de aminoácidos que no contengan bisulfitos. Conclusiones: Se concluye que se pueden administrar conjuntamente vitaminas y oligoelementos y preparar la NP con anterioridad a su administración cuando se utiliza NP "todo en uno", bolsas multicapa, soluciones de aminoácidos sin bisulfitos y fotoprotección. Resumen en inglés Objective: Some decades ago, several studies were published describing vitamins degradation in parenteral nutrition (PN) and their catalysis by oligoelements such as copper. Thus, the practice of administering oligoelements and vitamins every other day and adding them the same day of PN was implemented. Today, in many Spanish hospitals these recommendations are still being followed although currently different products, type of containers, and ways of administration are u (mas) sed. The purpose of this review is to determine whether combined administration of vitamins and oligoelements with PN is recommended and how many days they remain stable while refrigerated under the current conditions of preparation and administration of PN. Setting: We have reviewed the articles on vitamins stability in PN published after 1990. Results: The results are controversial with vitamin A, although "all-in-one" administration and photo-protection remarkably decrease its degradation and there seems to be no difference between adding the vitamin before its administration and doing so previously. Vitamin E is stable with photo-protection for 3-7 days under refrigeration plus one additional day at room temperature if multilayered bags are used. Thiamine is stable if bisulfites-free amino acids solutions are used. Conclusions: We conclude that vitamins and oligoelements may be administered together and PN be prepared before use if "all-in-one" photo-protected multilayered bags and bisulfite-free amino acids solutions are used.

Scientific Electronic Library Online (Spanish)

105

Enzymatic synthesis of disaccharides by β-galactosidase-catalyzed glycosylation of a glycocluster

Santiago, Reyes de ; Fernández-Mayoralas, Alfonso ; García-Junceda, Eduardo

9 pages, 2 figures, 3 schemes.-- Printed version published Dec 12, 2000. | The synthesis of disaccharides by galactosylation of a glucose-containing cluster has been studied using β-galactosidases from different sources. Galactosylation of the cluster could be detected by ESI-MS. After size-exclusio...

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106

Enzymatic synthesis of disaccharides by β-galactosidase-catalyzed glycosylation of a glycocluster

Santiago, Reyes de; Fernández-Mayoralas, Alfonso; García-Junceda, Eduardo
2000-10-16

Digital.CSIC (Spain)

107

Engineering and applications of fungal laccases for organic synthesis

Kunamneni, Adinarayana; Camarero, Susana; García-Burgos, Carlos; Plou, Francisco J.; Ballesteros, Antonio; Alcalde, Miguel
2008-01-01

Digital.CSIC (Spain)

108

Engineering and Applications of fungal laccases for organic synthesis

Kunamneni, Adinarayana; Camarero, Susana; García-Burgos, Carlos; Plou Gasca, Francisco José; Ballesteros, Antonio; Alcalde Galeote, Miguel
2008-11-20

Digital.CSIC (Spain)

109

Encapsulation of nanosized catalysts in the hollow core of a mesoporous carbon capsule

Valdés-Solís Iglesias, Teresa ; Valle Vigón, Patricia ; Sevilla Solís, Marta ; Fuertes Arias, Antonio Benito

5 pages, 5 figures.-- Printed version published Oct 1, 2007. | We present a novel synthetic method for the fabrication of encapsulated nanosized catalysts that have a core/shell structure consisting of numerous inorganic nanoparticles confined within the hollow core of a mesoporous carbon capsule. S...

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110

Encapsulation of nanosized catalysts in the hollow core of a mesoporous carbon capsule

Valdés-Solís Iglesias, Teresa; Valle Vigón, Patricia; Sevilla Solís, Marta; Fuertes Arias, Antonio Benito
2007-08-28

Digital.CSIC (Spain)

111

Elucidation of the Molecular Recognition of Bacterial Cell Wall by Modular Pneumococcal Phage Endolysin Cpl-1

Pérez-Dorado, Inmaculada; Campillo, Nuria E.; Monterroso, Begoña; Hesek, Dusan; Lee, Mijoon; Páez, Juan A.; García, Pedro; Martínez-Ripoll, Martín; García, José L.; Mobashery, Shahriar; Menéndez, Margarita; Hermoso, Juan A.
2007-08-01

Digital.CSIC (Spain)

112

Electronic potential of a chemisorption interface

Zhao, Jin ; Pontius, Niko ; Winkelmann, Aimo ; Sametoglu, Vahit ; Kubo, Atsushi ; Borisov, Andrei G. ; Sánchez-Portal, Daniel

7 pages, 4 figures.-- PACS nrs.: 73.20.-r. | Chemisorption of atoms and molecules controls many interfacial phenomena such as charge transport and catalysis. The question of how the intrinsic properties of the interacting materials define the electronic structure of their interface remains one of th...

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113

Electronic potential of a chemisorption interface

Zhao, Jin; Pontius, Niko; Winkelmann, Aimo; Sametoglu, Vahit; Kubo, Atsushi; Borisov, Andrei G.; Sánchez-Portal, Daniel; Silkin, Viatcheslav M.; Chulkov, Eugene V.; Echenique, Pedro M.; Petek, Hrvoje
2008-08-13

Digital.CSIC (Spain)

114

Electron transfer to sulfides and disulfides: intrinsic barriers and relationship between heterogeneous and homogeneous electron-transfer kinetics

Meneses, Ana Belén; Antonello, Sabrina; Arévalo, Maria Carmen; González Martín, Concepción C.; Sharma, Jadab; Wallette, Andrea N.; Workentin, Mark S.; Maran, Flavio
2007-07-06

Digital.CSIC (Spain)

116

Electrocatalytic oxidation of nitrite to nitrate mediated by Fe(III) poly-3-aminophenyl porphyrin grown on five different electrode surfaces

Armijo, Francisco ; Goya, M. Carmen ; Reina, Matías ; Canales, M. Josefina ; Arévalo, M. Carmen ; Aguirre, M. Jesús

7 pages, 6 figures, 1 table.-- Available online Dec 8, 2006. | Conducting poly-tetrakis(3-aminophenyl) porphyrin-Fe(III) chloride films are prepared by electropolymerization of the complex on five different electrode surfaces: highly oriented pyrolytic graphite (HOPG), glassy carbon (GC), transparen...

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117

Electrocatalytic oxidation of nitrite to nitrate mediated by Fe(III) poly-3-aminophenyl porphyrin grown on five different electrode surfaces

Armijo, Francisco; Goya, M. Carmen; Reina, Matías; Canales, M. Josefina; Arévalo, Maria Carmen; Aguirre, M. Jesús
2007-05-01

Digital.CSIC (Spain)

118

Effect of precursor nature on the behavior of titanium-polysiloxane homogeneous catalysts in primary alkene epoxidation

Blanco Brieva, Gema ; Capel Sánchez, M.ª Carmen ; Campos Martín, José Miguel ; García Fierro, José Luis

8 pages, 6 figures.-- Printed version published on May 18, 2007. | This work describes the synthesis, some structural characteristics and the performance of a series of titanium-containing polysiloxanes as homogeneous catalysts. These polysiloxanes were synthesized by mixing a titanium precursor, su...

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119

Effect of precursor nature on the behavior of titanium-polysiloxane homogeneous catalysts in primary alkene epoxidation

Blanco Brieva, Gema; Capel Sánchez, María del Carmen; Campos Martín, Jose Miguel; García Fierro, José Luis
2007-01-13

Digital.CSIC (Spain)

120

Effect of fluorine-containing chiral templates on Mg distribution in the structure of MgAPO-5 and its influence on catalytic activity

Gómez-Hortigüela, L.; Márquez-Alvarez, C.; Sastre, E.; Corà, F.; Pérez-Pariente, J.
2006-05-15

Digital.CSIC (Spain)

121

Efecto de la naturaleza del precursor sobre las caracteristicas de las nanoparticulas de SnO2 sintetizadas/ Effect of the precursor's nature on characteristics of synthesized SnO2 nanoparticles

Ararat-Ibarguen, Carlos E.; Montenegro, Alejandra; Rodríguez-Páez, Jorge E.; Urresta Aragón, Julián
2007-01-01

Resumen en inglés Tin oxide (SnO2) is widely used in industry as raw material for electronic devices, plating of different types of materials, for dyes and pigments, for electroplating, heterogeneous catalysis, etc. In this work SnO2 was obtained by a controlled precipitation method with special attention to the effects the tin precursor has on the microstructure of the final product. The most appropriate pH for obtaining SnO2 with the rutile structure as the main phase is 6.25 for SnCl2 a (mas) nd 6.40 for SnSO4. After heat treatment at 600 °C, particles of nanometric order (~10 - 30 nm approx) were obtained. The characterization of the solid phase was made by X-ray diffraction (XRD), thermal analysis (DTA/TG), transmission electron microscopy (TEM) and Fourier transformed infrared spectroscopy (FTIR).

Scientific Electronic Library Online (Spanish)

124

Discreteness effects in a reacting system of particles with finite interaction radius

Berti, S. ; López, Cristóbal ; Vergni, D. ; Vulpiani, Angelo

9 pages.-- PACS numbers: 05.40.-a, 82.39.-k, 82.40.-g.-- Final full-text version of the paper available at: http://dx.doi.org/10.1103/PhysRevE.76.031139. | An autocatalytic reacting system with particles interacting at a finite distance is studied. We investigate the effects of the discrete-particle...

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125

Discreteness effects in a reacting system of particles with finite interaction radius

Berti, S.; López, Cristóbal; Vergni, Davide; Vulpiani, Angelo
2007-04-10

Digital.CSIC (Spain)

126

Development of microporous carbon xerogels by controlling synthesis conditions

Zubizarreta Sáenz de Zaitegui, Leire ; Arenillas de la Puente, Ana ; Domínguez Padilla, Antonio ; Menéndez Díaz, José Ángel

9 pages, 7 figures, 4 tables. -- Available online 25 September 2007. | Textural properties of carbon gels can be controlled by varying the synthesis and drying process conditions. In this work, the influence of the initial pH and the drying method on the final properties of carbon gels, synthesized ...

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127

Development of microporous carbon xerogels by controlling synthesis conditions

Zubizarreta, Leire; Arenillas de la Puente, Ana; Domínguez Padilla, Antonio; Menéndez Díaz, José Ángel; Pis Martínez, José Juan
2008-02-01

Digital.CSIC (Spain)

128

Corrigendum to “Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst” [Catal. Comm. 8 (2007) 2037–2042]

Valdés-Solís Iglesias, Teresa ; Valle Vigón, Patricia ; Álvarez García, Sonia ; Marbán Calzón, Gregorio

1 page. -- Printed version published Sep 2008. -- Correction to: "Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst" [Catalysis Communications 8(12): 2037-2042 (2007)], http://digital.csic.es/handle/10261/11594 | The units of the reaction rate...

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129

Corrigendum to “Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst” [Catal. Comm. 8 (2007) 2037–2042]

Valdés-Solís Iglesias, Teresa; Valle Vigón, Patricia; Álvarez García, Sonia; Marbán Calzón, Gregorio; Fuertes Arias, Antonio Benito
2008-08-05

Digital.CSIC (Spain)

130

Correlación entre la estructura de bandas y las propiedades físicas de óxidos cerámicos de estructura perovsquita con metales de transición (II): Propiedades magnéticas y electrocatalíticas | Relationship between band structure and Physical properties in transition metal ceramic oxides with perovskite structure: (II) Magnetic and electrocatalytic properties

Jurado Egea, José Ramón ; Sánchez, L.

[ES] Se revisan los principales modelos teóricos y parámetros presentes en la literatura, que pretenden dar una explicación sobrelas propiedades magnéticas y electrocatalíticas de óxidos cerámicos con estructura perovsquita, en los que en la posición Bse encuentran los metales de transición (Fe, C...

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133

Comparative behaviour of proteinases from the latex of Carica papaya and Funastrum clausum as catalysts for the synthesis of Z-Ala-Phe-OMe

Morcelle, Susana R. ; Barberis, Sonia ; Priolo, Nora ; Caffini, Néstor O. ; Clapés Saborit, Pere

8 pages, 4 figures.-- Printed version published Aug 4, 2006. | The proteolytic extract obtained from the latex of Funastrum clausum (Jacq.) Schlechter (Asclepiadaceae), a South American climbing plant, was assayed as a novel catalyst for peptide synthesis and compared with commercial papain under t...

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134

Comparative behaviour of proteinases from the latex of Carica papaya and Funastrum clausum as catalysts for the synthesis of Z-Ala-Phe-OMe

Morcelle, Susana R.; Barberis, Sonia; Priolo, Nora; Caffini, Néstor O.; Clapés Saborit, Pere
2006-06-30

Digital.CSIC (Spain)

135

Combined removal of diesel soot particulates and NOx over CeO2–ZrO2 mixed oxides

Atribak, Idriss; Bueno López, Agustín; García García, Avelina

CeO2 and Ce–Zr mixed oxides with different Ce:Zr ratios were prepared; characterised by Ramanspectroscopy, XRD, TEM, N2 adsorption at −196 ◦C, and H2-TPR; and tested for soot oxidation underNOx/O2. Among the different mixed oxides, Ce0.76Zr0.24O2 provided the best results. Ce0.76Zr0.24O2presented...

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136

Combined alkyl and sulfonic acid functionalization of MCM-41-type silica. Part I. Synthesis and characterization

Díaz, Isabel ; Márquez Alvarez, Carlos ; Mohino, Federico ; Pérez-Pariente, Joaquín ; Sastre, Enrique

Single-step synthesis of well ordered, MCM-41 materials containingsimultaneously alkyl (methyl or propyl) and 3-mercaptopropyl groups has been carriedout by hydrothermal treatment of gels containing a mixture of dodecyl andhexadecyltrimethylammonium surfactants. A wide range of synthesis conditio...

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137

Combined alkyl and sulfonic acid functionalization of MCM-41-type silica. Part I. Synthesis and characterization

Díaz, Isabel; Márquez Álvarez, Carlos; Mohino, Federico; Pérez Pariente, Joaquín; Sastre de Andrés, Enrique
2000-01-01

Digital.CSIC (Spain)

138

Combined Alkyl and Sulfonic Acid Functionalization of MCM-41-Type Silica: Part 2. Esterification of Glycerol with Fatty Acids

Díaz, Isabel ; Márquez Alvarez, Carlos ; Mohino, Federico ; Pérez-Pariente, Joaquín ; Sastre, Enrique

8 pages, 10 figures, 4 tables. | The esterification of glycerol with lauric and oleic acids (1 : 1 molar ratio) has been carried out by using hybrid MCM-41 materials containing simultaneously alkyl (methyl or propyl) and sulfonic acid groups as catalysts. It has been found that for each fatty acid t...

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139

Combined Alkyl and Sulfonic Acid Functionalization of MCM-41-Type Silica: Part 2. Esterification of Glycerol with Fatty Acids

Díaz, Isabel; Márquez Álvarez, Carlos; Mohino, Federico; Pérez Pariente, Joaquín; Sastre de Andrés, Enrique
2000-07-25

Digital.CSIC (Spain)

140

Chemoenzymatic Synthesis and Inhibitory Activities of Hyacinthacines A1 and A2 Stereoisomers.

Calveras Ibáñez, Jordi ; Casas, Josefina ; Parella, Teodor ; Joglar, Jésus ; Clapés, Pere

6 páginas,1 figura, 2 esquemas, 2 tablas. | A novel straightforward chemoenzymaticprocedure for the synthesis of hyacinthacine stereoisomersbased on the aldol addition of dihydroxyacetonephosphate (DHAP) to N-Cbz-prolinal undercatalysis by l-rhamnulose 1-phosphate aldolasefrom E. coli is presen...

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141

Chemoenzymatic Synthesis and Inhibitory Activities of Hyacinthacines A1 and A2 Stereoisomers.

Calveras Ibáñez, Jordi; Casas, Josefina; Parella, Teodor; Joglar Tamargo, Jesús; Clapés Saborit, Pere
2007-07-17

Digital.CSIC (Spain)

142

Characterization and application of a sterol esterase immobilized on polyacrylate epoxy-activated carriers (DilbeadsTM)

Torres, Pamela; Datla, A; Rajasekar, V.W.; Zambre, S; Ashar, T; Yates Buxcey, Malcolm; Rojas-Cervantes, M. Luisa; Calero Rueda, Olga; Barba, V.; Martinez, M. J.; Ballesteros, Antonio; Plou Gasca, Francisco José
2008-01-01

Digital.CSIC (Spain)

144

C1-symmetric versus C2-symmetric ligands in enantioselective copper-bis(oxazoline)-catalyzed cyclopropanation reactions

Fraile, José M.; García, José I.; Gissibl, Anja; Mayoral, José A.; Pires, Elísabet; Reiser, Oliver; Roldán, Marta; Villalba, Isabel
2007-08-02

Digital.CSIC (Spain)

145

Binap-gold(I) trifluoroacetate as a bifunctional catalyst for the synthesis of chiral prolines through 1,3-dipolar cycloaddition of azomethine ylides

Martín Rodríguez, María; Nájera Domingo, Carmen; Sansano Gil, José Miguel; Wu, Feng-Liu

Highly enantioselective 1,3-dipolar cycloadditions of amino acid-derived azomethine ylides with alkenes have been performed, for the first time, under gold-catalysis using (Sa)- or (Ra)-Binap-gold(I) trifluoroacetate complexes, with the cationic Binap-gold acting as a Lewis acid and the counteranion...

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146

Bifunctional Binols: Chiral 3,3'-Bis(aminomethyl)-1,1'-bi-2-naphthols (Binolams) in asymmetric catalysis

Nájera Domingo, Carmen; Sansano Gil, José Miguel; Saá Rodríguez, José Manuel

3,3'-Bis(dialkylaminomethyl)-1,1'-binaphth-2-ols (Binolams) have emerged during the last five years as very efficient chiral ligands in many enantioselective processes. Enantiomerically pure Binolams are easily accessible by means of a variety of methods, the most widely used being the so-called chi...

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147

BINAP-AgSbF6 vs. BINAP-AgCIO4 complexes as catalysts for the enantio-selective 1,3-dipolar cycloaddition of azomethine ylides and alkenes

Martín Rodríguez, María; Nájera Domingo, Carmen; Sansano Gil, José Miguel; Costa, Paulo R.R.; Crizanto de Lima, Evanoel

The employment of AgSbF6 and BINAP ligands has been evaluated in the catalyzed enantioselective 1,3-dipolar cycloadditions between azomethine ylides and electrophilic alkenes. The results are compared with the analogous ones obtained when using AgClO4. The cycloaddition with maleimides and trans-1,2...

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148

Arylation of Benzo-Fused 1,4-Quinones by the Addition of Boronic Acids under Dicationic Pd(II)-Catalysis

Molina, María Teresa; Navarro, Cristina; Moreno, Ana; Csákÿ, Aurelio G.
2009-01-01

Digital.CSIC (Spain)

149

Aldol additions of dihydroxyacetone phosphate to N-Cbz-amino aldehydes catalyzed by L-fuculose-1-phosphate aldolase in emulsion systems: inversion of stereoselectivity as a function of the acceptor aldehyde

Espelt, Laia; Bujons Vilàs, Jordi; Parella, Teodor; Calveras Ibáñez, Jordi; Joglar Tamargo, Jesús; Delgado Cirilo, Antonio; Clapés Saborit, Pere
2005-01-24

Digital.CSIC (Spain)

150

Activation in the family of Candida rugosa isolipases by polyethylene glycol

Otero, Cristina ; Fernández-Pérez, Mónica ; Hermoso, Juan A. ; Martínez-Ripoll, Martín

Disponible en: http://www.xtal.iqfr.csic.es/publications/jmolcat2005.pdf | We have investigated activation of two isoenzymes (lip1 and lip3) from Candida rugosa in polyethylene glycol (PEG) media. Aqueoussolutions of PEG 8000 and 20,000 activate lip3 but not lip1 from C. rugosa. Maximum activation ...

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151

Activation in the family of Candida rugosa isolipases by polyethylene glycol

Otero, Cristina; Fernández-Pérez, Mónica; Hermoso, Juan A.; Martínez-Ripoll, Martín
2005-06-11

Digital.CSIC (Spain)

152

Activated α, β-Unsaturated Aldehydes as Substrate of Dihydroxyacetone Phosphate (DHAP)-Dependent Aldolases in the Context of a Multienzyme System

Sánchez-Moreno, Israel; Iturrate Montoya, Laura; Doyagüez, Elisa G.; Martínez, José Antonio; Fernández-Mayoralas, Alfonso; García-Junceda, Eduardo
2009-11-10

Digital.CSIC (Spain)

153

A comparative study on androgen metabolism in three invertebrate species

Janer, Gemma; LeBlanc, G. A.; Porte Visa, Cinta
2005-05-25

Digital.CSIC (Spain)

154

A Zeolite Structure (ITQ-13) with Three Sets of Medium-Pore Crossing Channels Formed by 9- and 10-Rings

Corma, Avelino ; Puche, Marta ; Rey García, Fernando ; Sankar, Gopinathan ; Teat, Simon J.

Final full-text version of the paper available at Angewandte Chemie International Edition website: http://dx.doi.org/10.1002/anie.200390304.-- Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2003/z50514_s.pdf or from the author.-- Corrig...

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155

A Zeolite Structure (ITQ-13) with Three Sets of Medium-Pore Crossing Channels Formed by 9- and 10-Rings

Corma, Avelino; Puche, Marta; Rey García, Fernando; Sankar, Gopinathan; Teat, Simon J.
2003-03-10

Digital.CSIC (Spain)

156

A Transition Path Sampling Study of the Reaction Catalyzed by the Enzyme Chorismate Mutase

Crehuet, Ramón ; Field, Martin J.

11 pages, 14 figures.-- PMID: 17474768 [PubMed]. | The study of the chemical steps in enzyme-catalyzed reactions represents a challenge for molecular simulation techniques. One concern is how to calculate paths for the reaction. Common techniques include the definition of a reaction coordinate in te...

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158

A New Hydrogen Sensor Based on a Pt/GaAs Schottky Diode

Lechuga, Laura M.; Calle Martín, Ana; Golmayo, Dolores; Tejedor, P.; Briones Fernández-Pola, Fernando
1991-01-01

Digital.CSIC (Spain)