Adsorption of probe molecules in pillared interlayered clays: experiment and computer simulation.

In this paper we investigate the adsorption of various probe molecules in order to characterize the porous structure of a series of pillared interlayered clays (PILC). To that aim, volumetric and microcalorimetric adsorption experiments were performed on various Zr PILC samples using nitrogen, toluene, and mesitylene as probe molecules. For one of the samples, neutron scattering experiments were also performed using toluene as adsorbate. Various structural models are proposed and tested by means of a comprehensive computer simulation study, using both geometric and percolation analysis in combination with Grand Canonical Monte Carlo simulations in order to model the volumetric and microcalorimetric isotherms. On the basis of this analysis, we propose a series of structural models that aim at accounting for the adsorption experimental behavior, and make possible a microscopic interpretation of the role played by the different interactions and steric effects in the adsorption processes in these rather complex disordered microporous systems.

Topological considerations on microporous adsorption processes in simple models for pillared interlayered clays.

The microporous structure of pillared interlayered clays is determined by their interlayer separation and the distribution of the pillars that separate their layers. The pillars provide stability to these quasi-two-dimensional high surface area materials. In this work we present a topological analysis of available and accessible volumes within various simple models of pillared interlayered clays. Each model is characterized by a distribution of pillars. Both fully ordered structures and disordered pillar distributions with either attractive or repulsive interpillar correlations are considered. Particular attention is paid to the problem of accessibility. In systems with similar degrees of porosity, even when cavities within each model might be able to host the same adsorbate molecules, their accessibility will strongly depend on the pillar distribution. The theoretical analysis presented in this work may facilitate the interpretation of experimental results, pointing out those quantities that are key to describe the texture of the porous material.

Gestión del transporte sanitario desde un servicio de urgencias / Emergency department management of ambulance services

Objetivo: Conocer si la gestión del transporte sanitario en ambulancia desde el servicio de urgencias hospitalario disminuye el tiempo de espera y las reclamaciones por la demora del mismo. Método: Análisis prospectivo y comparativo de dos periodos de tiempo, uno sin gestión del transporte sanitario (SGTS) en los meses de octubre y noviembre de 2007, y otro con gestión (CGTS) desde el servicio de urgencias en los meses de diciembre de2007 y enero de 2008. Se recogieron el número de transportes realizados, el tiempo de demora y las quejas recibidas en los dos periodos. Se excluyeron los transportes urgentes de pacientes en ambulancia a otros centros hospitalarios. Resultados: Durante el periodo SGTS se realizaron 544 evacuaciones y en el periodo CGTS 720. La demora media en el periodo SGTS fue de 2 horas y 4 minutos (espera máxima: 8 horas) y en el CGTS fue de 1 hora y 1 minuto (espera máxima: 4 horas). Durante el periodo SGTS se realizaron 5 quejas por escrito y 64 quejas orales en relación al transporte sanitario, mientras que en el CGTS no hubo quejas por escrito y se registraron 19 quejas orales. En este último periodo hubo el doble de transportes múltiples(2 pacientes en la misma ambulancia) que en el periodo SGTS. Conclusión: La gestión del transporte sanitario desde el servicio de urgencias en el periodo de estudio supuso una franca mejoría en las variables estudiadas (AU)

Objective: To determine whether hospital emergency service management of ambulance services reduces wait time and complaints about delayed transport. Methods: A prospective study comparing 2 periods of time, one in which ambulance service was not managed by the hospital emergency department (October and November 2007) and another in which the department did manage the ambulance service (December 2007 and January 2008). The number of transfers, transport time, and complaints received in the 2 periods were analyzed. Ambulance trips taking patients to other hospitals were excluded from the analysis. Results: During the first period, patients from 544 emergency calls were brought in; in the second period, the service responded to 720 calls for emergency transport. In the first study period, the mean wait time was 2 hours and 4 minutes(maximum wait time, 8 hours). In the second period, the mean wait time was 1 hour and 1 minute (maximum, 4hours). Five complaints about emergency transport (9 written, 64 verbal) were lodged in the first period. The second period saw no written complaints and 19 verbal complaints. Twice the number of double transports (2 patients in the same ambulance) took place in the second period with in the first period. Conclusion: Emergency department management of ambulance services brought considerable improvement in the variables studied (AU)

XPS and 1H NMR study of thermally stabilized Rh/CeO2 catalysts submitted to reduction/oxidation treatments.

Rh/CeO2 catalysts submitted to different H2 reduction, Ar+ sputtering, and oxidation treatments have been studied by X-ray photoelectron (XPS) and 1H nuclear magnetic resonance (NMR) spectroscopies. Depending on the reduction temperature, two stages have been identified in the reduction of the catalyst: below 473 K, reduction increases the amount of OH and Ce3+ species; above this temperature, reduction produces oxygen vacancies at the surface of the support. Volumetric and microcalorimetric techniques have been used to study hydrogen adsorption on the catalyst, and 1H NMR spectroscopy was used to differentiate hydrogen adsorbed on the metal from that adsorbed on the support. From 1H NMR and TEM results, the main metal particle size (38 A) in the Rh/CeO2 catalyst has been estimated. The influence of the support reduction on the metal adsorption capacity has also been investigated, showing that formation of oxygen vacancies at the metal-support interface enhances the electronic perturbation and decreases the hydrogen adsorption on metal particles. The comparison of data reported on catalysts of high and low surface area supports has shown that both processes are shifted to higher temperatures in the Rh/CeO2 catalyst of lower surface area.

Nutritional and toxic factors in selected wild edible plants.

Nutritional (ascorbic acid, dehydroascorbic acid and carotenes); antinutritional and toxic components (oxalic acid, nitrate and erucic acid) were determined in sixteen popular species of wild edible plants which are collected for human consumption in southeast Spain. Ascorbic + dehydroascorbic acids contents were very high in several species, especially in Chenopodium album L. (155 mg/100 g). Carotenoid content ranged from 4.2 mg/100 g (Stellaria media Villars) to 15.4 mg/100 g (Amaranthus viridis L.). A range of values was found for oxalic acid from absence to 1100 mg/100 g of plant material. Nitrate contents ranged from 47 mg/100 g (Salicornia europaea L.) to 597 mg/100 g (Amaranthus viridis L.). Low amounts of erucic acid were found in the Cruciferae family (Sisymbrium irio L. 1.73%; Cardaria draba L. 1.23%) and Plantago major L. 3.45%.

Identification of fatty acids in edible wild plants by gas chromatography.

The total lipidic content and the distribution of fatty acids in twenty edible wild plants in S.E. Spain was determined by GC. The lipidic content was higher than usual in the common vegetables. The high ratio of the omega 3 series of unsaturated fatty acids relative to the omega 6 series demonstrates the good nutritional qualities of these plants.