Abstract In this study, fast chiral separations were demonstrated using near-critical carbon diox... more Abstract In this study, fast chiral separations were demonstrated using near-critical carbon dioxide as mobile phase. Most separations were carried out in less than 1 min at 30 C using 1215 cm capillary columns packed with 5 μm porous (300 Å) silica particles deactivated ...
Abstract In this study, fast chiral separations were demonstrated using near-critical carbon diox... more Abstract In this study, fast chiral separations were demonstrated using near-critical carbon dioxide as mobile phase. Most separations were carried out in less than 1 min at 30 C using 1215 cm capillary columns packed with 5 μm porous (300 Å) silica particles deactivated ...
Hydrocarbon hydrogenolysis and CO2 hydrogenation in the presence of Fe/SiO2 and Ni/SiO2 catalysts... more Hydrocarbon hydrogenolysis and CO2 hydrogenation in the presence of Fe/SiO2 and Ni/SiO2 catalysts were evaluated as potential mechanisms contributing to natural gas formation in coalbeds. The hydrocarbons used as reactants in hydrogenolysis included butane, octane, 1-octene, and 1-dodecene. The reactions carried out in a laboratory batch reactor produced gas that contained methane concentrations greater than 90%, which resembles the composition of natural gas. Reaction temperatures were selected to resemble natural coalbed conditions. Evidence is presented to show that iron and nickel minerals, which can be present in coals at levels of 2000 and 10 ppm, respectively, can become active under geologic conditions. The oxides (Fe2O3 and NiO) used as precursors of the active catalysts (Fe and Ni metals) were reduced at 200°C under a hydrogen atmosphere. Mössbauer spectroscopy showed that ca. 6% of the iron oxide was converted to the metal; in the case of nickel, oxygen titration showed that the extent of reduction to the metal was ca. 29%. The resultant fractions of the active metals in coals are adequate to catalyze generation of appreciable amounts of methane over geologic time.
Abstract In this study, fast chiral separations were demonstrated using near-critical carbon diox... more Abstract In this study, fast chiral separations were demonstrated using near-critical carbon dioxide as mobile phase. Most separations were carried out in less than 1 min at 30 C using 1215 cm capillary columns packed with 5 μm porous (300 Å) silica particles deactivated ...
Abstract In this study, fast chiral separations were demonstrated using near-critical carbon diox... more Abstract In this study, fast chiral separations were demonstrated using near-critical carbon dioxide as mobile phase. Most separations were carried out in less than 1 min at 30 C using 1215 cm capillary columns packed with 5 μm porous (300 Å) silica particles deactivated ...
The synthesis and characterization of an iron cyclam-type complex within the cavities of a Y-zeol... more The synthesis and characterization of an iron cyclam-type complex within the cavities of a Y-zeolite is described. By comparing the performance of the heterogeneous system with the free complex in the oxidation of cyclohexene using iodosylbenzene as oxygen donor, a ...
To describe and analyze the characteristics of prehospital medical assistance provided by the Mad... more To describe and analyze the characteristics of prehospital medical assistance provided by the Madrid Municipal Emergency and Civil Rescue & Protection Service (SAMUR); and, based on the epidemiologic knowledge so gained, to prioritize public health intervention strategies. A retrospective cross-sectional analysis of all medical services performed by the SAMUR-Protección Civil in 2001 and 2002. Study variables included causes, response times, hour, day of the week, month, mobile resource, Municipal District, and pathology. For analysis purposes, the relevant data were linked to Access 97 via Open Database Connectivity. Statistical analysis was performed using the SPSS computer software package, with…
Packed capillary column solvating gas chromatography (SGC) and open tubular column gas chromatogr... more Packed capillary column solvating gas chromatography (SGC) and open tubular column gas chromatography (GC) were compared with respect to their potentials for fast separations. A recently introduced “universal” peak capacity equation was used to compare the performance of these two methods. The effects of various factors on peak capacity were investigated. Results demonstrate that retention factor and column efficiency are the main factors affecting peak capacity for fast separations. Packed columns produce both high retention factors and high selectivities. While high efficiencies and high peak capacities can be demonstrated by both techniques, open tubular column GC can surpass packed capillary column SGC in both measurements, except for the case of the analysis of simple mixtures in short analysis times, where retention factor and selectivity become important. Practical aspects such as pressure drop and sample capacity are compared for SGC and open tubular column GC. It was found that packed column SGC demonstrates higher sample capacities, but requires much higher column inlet pressures than open tubular column GC. A variety of mobile phases can be used for packed column SGC, which can provide high solvating power for large and polar compounds.
The synthesis and characterization of an iron cyclam-type complex within the cavities of a Y-zeol... more The synthesis and characterization of an iron cyclam-type complex within the cavities of a Y-zeolite is described. By comparing the performance of the heterogeneous system with the free complex in the oxidation of cyclohexene using iodosylbenzene as oxygen donor, a ...
Packed capillary column solvating gas chromatography (SGC) and open tubular column gas chromatogr... more Packed capillary column solvating gas chromatography (SGC) and open tubular column gas chromatography (GC) were compared with respect to their potentials for fast separations. A recently introduced "universal" peak capacity equation was used to compare the performance of these two methods. The effects of various factors on peak capacity were investigated. Results demonstrate that retention factor and column efficiency are the main factors affecting peak capacity for fast separations. Packed columns produce both high retention factors and high selectivities. While high efficiencies and high peak capacities can be demonstrated by both techniques, open tubular column GC can surpass packed capillary column SGC in both measurements, except for the case of the analysis of simple mixtures in short analysis times, where retention factor and selectivity become important. Practical aspects such as pressure drop and sample capacity are compared for SGC and open tubular column GC. It was found that packed column SGC demonstrates higher sample capacities, but requires much higher column inlet pressures than open tubular column GC. A variety of mobile phases can be used for packed column SGC, which can provide high solvating power for large and polar compounds.
Abstract In this study, fast chiral separations were demonstrated using near-critical carbon diox... more Abstract In this study, fast chiral separations were demonstrated using near-critical carbon dioxide as mobile phase. Most separations were carried out in less than 1 min at 30 C using 1215 cm capillary columns packed with 5 μm porous (300 Å) silica particles deactivated ...
Abstract In this study, fast chiral separations were demonstrated using near-critical carbon diox... more Abstract In this study, fast chiral separations were demonstrated using near-critical carbon dioxide as mobile phase. Most separations were carried out in less than 1 min at 30 C using 1215 cm capillary columns packed with 5 μm porous (300 Å) silica particles deactivated ...
Hydrocarbon hydrogenolysis and CO2 hydrogenation in the presence of Fe/SiO2 and Ni/SiO2 catalysts... more Hydrocarbon hydrogenolysis and CO2 hydrogenation in the presence of Fe/SiO2 and Ni/SiO2 catalysts were evaluated as potential mechanisms contributing to natural gas formation in coalbeds. The hydrocarbons used as reactants in hydrogenolysis included butane, octane, 1-octene, and 1-dodecene. The reactions carried out in a laboratory batch reactor produced gas that contained methane concentrations greater than 90%, which resembles the composition of natural gas. Reaction temperatures were selected to resemble natural coalbed conditions. Evidence is presented to show that iron and nickel minerals, which can be present in coals at levels of 2000 and 10 ppm, respectively, can become active under geologic conditions. The oxides (Fe2O3 and NiO) used as precursors of the active catalysts (Fe and Ni metals) were reduced at 200°C under a hydrogen atmosphere. Mössbauer spectroscopy showed that ca. 6% of the iron oxide was converted to the metal; in the case of nickel, oxygen titration showed that the extent of reduction to the metal was ca. 29%. The resultant fractions of the active metals in coals are adequate to catalyze generation of appreciable amounts of methane over geologic time.
Abstract In this study, fast chiral separations were demonstrated using near-critical carbon diox... more Abstract In this study, fast chiral separations were demonstrated using near-critical carbon dioxide as mobile phase. Most separations were carried out in less than 1 min at 30 C using 1215 cm capillary columns packed with 5 μm porous (300 Å) silica particles deactivated ...
Abstract In this study, fast chiral separations were demonstrated using near-critical carbon diox... more Abstract In this study, fast chiral separations were demonstrated using near-critical carbon dioxide as mobile phase. Most separations were carried out in less than 1 min at 30 C using 1215 cm capillary columns packed with 5 μm porous (300 Å) silica particles deactivated ...
The synthesis and characterization of an iron cyclam-type complex within the cavities of a Y-zeol... more The synthesis and characterization of an iron cyclam-type complex within the cavities of a Y-zeolite is described. By comparing the performance of the heterogeneous system with the free complex in the oxidation of cyclohexene using iodosylbenzene as oxygen donor, a ...
To describe and analyze the characteristics of prehospital medical assistance provided by the Mad... more To describe and analyze the characteristics of prehospital medical assistance provided by the Madrid Municipal Emergency and Civil Rescue & Protection Service (SAMUR); and, based on the epidemiologic knowledge so gained, to prioritize public health intervention strategies. A retrospective cross-sectional analysis of all medical services performed by the SAMUR-Protección Civil in 2001 and 2002. Study variables included causes, response times, hour, day of the week, month, mobile resource, Municipal District, and pathology. For analysis purposes, the relevant data were linked to Access 97 via Open Database Connectivity. Statistical analysis was performed using the SPSS computer software package, with…
Packed capillary column solvating gas chromatography (SGC) and open tubular column gas chromatogr... more Packed capillary column solvating gas chromatography (SGC) and open tubular column gas chromatography (GC) were compared with respect to their potentials for fast separations. A recently introduced “universal” peak capacity equation was used to compare the performance of these two methods. The effects of various factors on peak capacity were investigated. Results demonstrate that retention factor and column efficiency are the main factors affecting peak capacity for fast separations. Packed columns produce both high retention factors and high selectivities. While high efficiencies and high peak capacities can be demonstrated by both techniques, open tubular column GC can surpass packed capillary column SGC in both measurements, except for the case of the analysis of simple mixtures in short analysis times, where retention factor and selectivity become important. Practical aspects such as pressure drop and sample capacity are compared for SGC and open tubular column GC. It was found that packed column SGC demonstrates higher sample capacities, but requires much higher column inlet pressures than open tubular column GC. A variety of mobile phases can be used for packed column SGC, which can provide high solvating power for large and polar compounds.
The synthesis and characterization of an iron cyclam-type complex within the cavities of a Y-zeol... more The synthesis and characterization of an iron cyclam-type complex within the cavities of a Y-zeolite is described. By comparing the performance of the heterogeneous system with the free complex in the oxidation of cyclohexene using iodosylbenzene as oxygen donor, a ...
Packed capillary column solvating gas chromatography (SGC) and open tubular column gas chromatogr... more Packed capillary column solvating gas chromatography (SGC) and open tubular column gas chromatography (GC) were compared with respect to their potentials for fast separations. A recently introduced "universal" peak capacity equation was used to compare the performance of these two methods. The effects of various factors on peak capacity were investigated. Results demonstrate that retention factor and column efficiency are the main factors affecting peak capacity for fast separations. Packed columns produce both high retention factors and high selectivities. While high efficiencies and high peak capacities can be demonstrated by both techniques, open tubular column GC can surpass packed capillary column SGC in both measurements, except for the case of the analysis of simple mixtures in short analysis times, where retention factor and selectivity become important. Practical aspects such as pressure drop and sample capacity are compared for SGC and open tubular column GC. It was found that packed column SGC demonstrates higher sample capacities, but requires much higher column inlet pressures than open tubular column GC. A variety of mobile phases can be used for packed column SGC, which can provide high solvating power for large and polar compounds.
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