Catalytic Processing of Lactic Acid over Pt/Nb2O5

Dilute aqueous solutions of lactic acid (30 %wt.) can be catalytically processed at 573 K and 57 bar over a low-metal-content Pt(0.1 %)/Nb2O5 catalyst in a spontaneously separating organic phase rich in valuable products such as C4–C7 ketones. An increase in the lactic acid concentration to 60 wt % allows conversion of approximately 50 % of the carbon feed in this organic layer, while maintaining good stability of the catalyst. Experiments at low conversion showed that lactic acid reacts first over Pt(0.1 %)/Nb2O5 to produce acetaldehyde and propanoic acid (along with CO and CO2 in the gas phase). These compounds (less oxygenated than lactic acid but still reactive) are the key intermediates in the overall process, and they react differently depending on the nature of the catalyst support. In particular, reaction kinetics studies with propanoic acid as feed showed that Pt(0.1 %)/Nb2O5 favored the formation of pentanones by ketonization reactions, whereas a monofunctional Pt(0.1 %)/carbon catalyst produced ethane and COx by decomposition reactions. In the same manner, acetaldehyde was preferentially hydrogenated to ethanol over Pt(0.1 %)/carbon, whereas the presence of niobia allowed this intermediate to react (by successive aldol condensations) to form C4–C7 condensation products stored in the organic phase. Finally, reaction pathways are proposed to explain the catalytic processing of lactic acid over bifunctional Pt(0.1 %)/Nb2O5. In this scheme, metal sites catalyze hydrogenation reactions and niobia promotes CC coupling processes (ketonization and aldol condensation), in contrast to CC cleavage reactions which take place preferentially over Pt(0.1 %)/carbon and lead to loss of carbon in the gas effluent as CO, CO2, and methane.Es la versión preprint del artículo. Se puede consultar la versión final en https://doi.org/10.1002/cssc.20090000

Catalytic routes for the conversion of biomass into liquid hydrocarbon transportation fuels

Concerns about diminishing fossil fuel reserves along with global warming effects caused by increasing levels ofCO2 in the atmosphere are driving society toward the search for new renewable sources of energy that can substitute for coal, natural gas and petroleum in the current energy system. Lignocellulosic biomass is abundant, and it has the potential to significantly displace petroleum in the production of fuels for the transportation sector. Ethanol, the main biomass-derived fuel used today, has benefited from production by a well-established technology and by partial compatibility with the current transportation infrastructure, leading to the domination of the world biofuel market. However, ethanol suffers from important limitations as a fuel (e.g., low energy density, high solubility in water) than can be overcome by designing strategies to convert non-edible lignocellulosic biomass into liquid hydrocarbon fuels (LHF) chemically similar to those currently used in internal combustion engines. The present review describes the main routes available to carry out such deep chemical transformation (e.g., gasification, pyrolysis, and aqueous-phase catalytic processing), with particular emphasis on those pathways involving aqueous-phase catalytic reactions. These latter catalytic routes achieve the required transformations in biomass-derived molecules with controlled chemistry and high yields, but require pretreatment/ hydrolysis steps to overcome the recalcitrance of lignocellulose. To be economically viable, these aqueous-phase routes should be carried out with a small number of reactors and with minimum utilization of external fossil fuel-based hydrogen sources, as illustrated in the examples presented here

Estudio refractométrico y conoscópico de las gemas facetadas transparentes birrefringentes de la colección del Museu de Geologia de Barcelona

This work is a revision of faceted transparent birrefringent gems detailed in the catalogue of the collection of the Museu de Geologia published in 2000. The process use figures of interference as especially convincing method for a correct identification of these kind of gems. The Conoscope Figueras 93 is especially suitable for a clear and correct observation of figures of interference. The gemmological refractometer has been used for refractometric readings. Key words: Faceted gems, Figures of interference, Conoscope, Birrefringence, Refractometry, Catalogue, Museu de Geologia, Barcelona, Spain.Este trabajo recoge una revisión de las gemas facetadas birrefringentes del Museo de Geología de Barcelona, detalladas en un catálogo publicado en el año 2000. En el proceso de revisión se utilizan las figuras de interferencia como método más convincente para la correcta identificación de este tipo de gemas, estando el conoscopio Figueras 93 especialmente indicado para la mejor observación de estas figuras. Para las lecturas refractométricas se ha usado el refractómetro gemológico. Palabras clave: Gemas facetadas, Figuras de interferencia, Conoscopio, Birrefringencia, Refractometría, Catálogo, Museu de Geologia, Barcelona, España

Determinants of profitability in Spanish financial institutions. Comparing aided and non-aided entities

The last financial crisis has led to the greatest contribution of public funds ever made to Spanish banks. This paper studies why the need for support has been asymmetric, with not all of the institutions requiring aid. Based on profitability of assets (ROA), we determine using panel data econometric and logit response models the components of profit and loss accounts that generated profitability as well as the factors leading to some entities to ask for aid. The analyses show that before the beginning of the crisis there were significant differences between entities that needed aid and those that did not. The most profitable banks grounded their success in the traditional revenue components of financial institutions (such as margin on interest rates and commissions), as well as in revenues obtained from participated companies and extraordinary results. The model offers a tool to detect entities in difficulties in advance, reducing the financial and social costs of public interventions. The factors more impacting on profitability of Spanish institutions are also identifie

Resultados del tratamiento de la inestabilidad postdisectomia mediante artrodesis posterolateral lumbar

El mecanismo fisiopatológico por el cual, tras una discectomia en columna lumbar, se puede producir inestabilidad en este segmento de la columna, ha sido establecido en múltiples estudios y se encuentra en la bibliografía actual. Sin embargo, hay pocas publicaciones en la literatura que hagan referencia a los resultados de la artrodesis posterolateral lumbar en inestabilidad clínico-radiológica generada tras una discectomia lumbar. El propósito del presente estudio es valorar los resultados obtenidos en mejora de calidad de vida, en pacientes sometidos a artrodesis lumbar con tornillos pediculares en inestabilidad postdisectomía. La población estudiada se trató de 15 pacientes, 10 hombres y 5 mujeres con edades comprendidas entre los 27 y 65 años, la selección de los pacientes además del antecedente de cirugía discal, se basó en la presencia de un cuadro clínico de inestabilidad unido a pruebas radiológicas estáticas, dinámicas y resonancia magnética, y por último la ausencia de problemas de tipo laboral o psicológico, los datos se obtuvieron por entrevista personal y llamada telefónica, utilizando la escala de Oswestry y la escala analógica de Scott. Los resultados obtenidos fueron buenos ya que más del 90% de los pacientes refirieron mejoría en su calidad de vida. Se puede concluir que la artrodesis posterolateral con tornillos pediculares en inestabilidad postdisectomia, es una buena opción quirúrgica, con la cual se puede obtener mejoría del cuadro clínico del paciente.The present study has the aime, the evaluation of results of posterolateral lumbar arthrodesis in patients who had undergone lumbar discal surgery failed because of appearance of instability. Retrospective study in 15 patients with diagnosis instability postdiskectomy made by: clinical, static and dynamic x-ray and MRI, treated with posterolateral lumbar arthrodesis using pedicular screw. Ten males and five female of 27-65 years and average 46, we used the life quality scale Oswestry and Scott scale. The shortest follow up 3 years and longest 6 years. Our results were: time between diskectomy and arthrodesis variated from 1 to 10 years, average 5 years, about: pain intensity, patients need analgesic because pain, help for activities, deambulation, sexual activity all of them improve. We had 3 cases with clinical symptoms, the other one pain free. One case of deep infection of wound where surgical debridement was necessary. Finally Scott¿s scale prior to surgery punctuation was between 1-4. after between 8-10. Excepting 1 case with bad evolution. Conclusion: posterolateral lumbar arthrodesis with pedicular screew can be a good option of treatment in instability postdikectomy

Catalytic coupling of carboxylic acids by ketonization as a processing step in biomass conversion

Carboxylic acids, common intermediate products in biomass conversion processes, can be converted into ketones via ketonization reactions over a ceria–zirconia catalyst. Reaction kinetics studies were carried out using hexanoic acid, as a representative carboxylic acid, in the presence of 1-pentanol and 2-butanone, as representative biomass-derived alcohol and ketone species. Studies were carried out at temperatures from 448 to 623K, and employing a range of hexanoic acid partial pressures from 0.05 to 0.3atm. Two different reactions were observed to take place at these reaction conditions: esterification and ketonization, both consuming hexanoic acid. Product inhibition by water and carbon dioxide was observed and studied by co-feeding these components to the reactor. Hexanoic acid adsorption on the catalyst surface is an important step in the reaction, and the rate of ketonization shifts from second order to zero order as the partial pressure of acid increases. The measured activation energy for the ketonization of hexanoic acid (132kJ/mol) is higher than the esterification reaction (40kJ/mol), such that the irreversible ketonization reaction is favored at higher temperatures (>573K) compared to the reversible esterification reaction. Direct ketonization of esters does not take place in the presence of acids, and instead takes place by hydrolysis with water followed by ketonization of the corresponding acid. The results of this study can be described by a simple kinetic model including site blocking by adsorbed hexanoic acid, carbon dioxide, and water.Es la versión preprint del artículo. Se puede consultar la versión final en https://doi.org/10.1016/j.jcat.2009.05.01

Google es noticia. Transformación de los marcos informativos sobre Google en la prensa española

Fundada en 1998, en menos de veinte años, Google se ha convertido en una de las mayores multinacionales del mundo. Esta investigación estudia las informaciones periodísticas sobre Google, desde la perspectiva de la teoría del encuadre (framing). La pregunta propuesta es: ¿Ha cambiado la imagen que la prensa española proyecta sobre Google desde los inicios de la compañía a los últimos años? Para responder, se ha hecho un análisis de contenido de todos los textos periodísticos sobre Google publicados en 2004 y 2014 por “El País”, “El Mundo”, “ABC” y “La Vanguardia”. Mediante un protocolo de análisis, se han detectado los marcos informativos –news frames– presentes en cada texto periodístico. Los resultados de la investigación ponen de manifiesto que se ha producido una transformación de los marcos informativos sobre Google: de ser mayoritariamente positivos para la compañía estadounidense, a ser negativos. También se ha detectado que, en 2004, las informaciones sobre la empresa ponían el foco en cuestiones de tipo económico; mientras que, en 2014, los periódicos analizados prefirieron atribuir a Google la responsabilidad de una serie de problemas. El texto concluye que Google ya no es enmarcada por los principales diarios sólo como una empresa tecnológica que logra excelentes resultados económicos, sino como una compañía cuyas actividades afectan –con frecuencia, negativamente– a determinadas personas, grupos humanos y a otras compañías

Early Science with the Large Millimetre Telescope: Molecules in the Extreme Outflow of a proto-Planetary Nebula

Extremely high velocity emission likely related to jets is known to occur in some proto-Planetary Nebulae. However, the molecular complexity of this kinematic component is largely unknown. We observed the known extreme outflow from the proto-Planetary Nebula IRAS 16342-3814, a prototype water fountain, in the full frequency range from 73 to 111 GHz with the RSR receiver on the Large Millimetre Telescope. We detected the molecules SiO, HCN, SO, and $^{13}$CO. All molecular transitions, with the exception of the latter are detected for the first time in this source, and all present emission with velocities up to a few hundred km s$^{-1}$. IRAS 16342-3814 is therefore the only source of this kind presenting extreme outflow activity simultaneously in all these molecules, with SO and SiO emission showing the highest velocities found of these species in proto-Planetary Nebulae. To be confirmed is a tentative weak SO component with a FWHM $\sim$ 700 km s$^{-1}$. The extreme outflow gas consists of dense gas (n$_{\rm H_2} >$ 10$^{4.8}$--10$^{5.7}$ cm$^{-3}$), with a mass larger than $\sim$ 0.02--0.15 M$_{\odot}$. The relatively high abundances of SiO and SO may be an indication of an oxygen-rich extreme high velocity gas.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society Letter