Las cátedras granadinas del Conservatorio de Artes (1833-1845)

En este artículo se hace un recorrido sobre las cátedras granadinas para obre¬ros y artesanos creadas al comienzo de la época liberal. En 1833, las enseñanzas del Conservatorio de Artes de Madrid se extendieron a diversas ciudades españolas, con el objetivo de ofrecer una enseñanza básica a los trabajadores vinculados a la actividad industrial. En Granada se creó una cátedra de geometría y mecánica y otra de química aplicada, que estuvieron bajo el control de la Sociedad Económica de Amigos del País. Aunque las cátedras estaban orientadas a la formación de obreros y artesanos, la mayor parte de los alumnos eran estudiantes universitarios. En 1837 la Sociedad Económica abandonó la dirección de las cátedras. Sólo siguió funcionando la de química, que fue vinculándose cada vez más a la Universidad hasta que en 1845, el profesor de química fue nombrado catedrático de dicha materia

Titanium scaffolds with multi-scale porosity obtained by controlled chemical and electrochemical treatments of porous solids from PM space holder technique

Junta de Andalucía (Spain) / FEDER (EU), through the project Ref. P12-TEP-140

La investigación química en Granada en el siglo actual (1900-1975)

Se estudia el desarrollo de la investigación en Química en Granada entre 1900 y 1975, efectuando en primer lugar un estudio cuantitativo sobre el conjunto de la producción bibliográfica, y sobre los distintos periodos (1900-1936,1937-1955 y 1956-1975) en que se han dividido arbitrariamente los tres cuartos de siglo considerados. A continuación se realiza una descripción de las más importantes líneas investigadoras cultivadas en Granada en el campo de la Química, tanto en los centros universitarios como en los dependientes del Consejo Superior de Investigaciones Científicas (CSIC), haciendo algunas consideraciones sobre las características y las aportaciones de esta actividad investigadora. Del estudio realizado se observa que la investigación científica se fue consolidando lentamente en los años treinta. La guerra civil modificó sustancialmente la situación y, ya en la postguerra, la importante influencia del CSIC determinó que las investigaciones en el campo de silicatos y minerales arcillosos (mineralogía, reactividad, aplicaciones) fueran las más numerosas hasta bien entrados los años sesenta. A partir de 1965, la investigación se fue diversificando, aumentando en importancia los trabajos sobre temas de Bioquímica, Fisiología y Química Analítica

Gravitational induced particle production through a nonminimal curvature-matter coupling

We consider the possibility of a gravitationally induced particle production through the mechanism of a nonminimal curvature-matter coupling. An interesting feature of this gravitational theory is that the divergence of the energy-momentum tensor is nonzero. As a first step in our study we reformulate the model in terms of an equivalent scalar-tensor theory, with two arbitrary potentials. By using the formalism of open thermodynamic systems, we interpret the energy balance equations in this gravitational theory from a thermodynamic point of view, as describing irreversible matter creation processes. The particle number creation rates, the creation pressure, and the entropy production rates are explicitly obtained as functions of the scalar field and its potentials, as well as of the matter Lagrangian. The temperature evolution laws of the newly created particles are also obtained. The cosmological implications of the model are briefly investigated, and it is shown that the late-time cosmic acceleration may be due to particle creation processes. Furthermore, it is also shown that due to the curvature--matter coupling, during the cosmological evolution a large amount of comoving entropy is also produced.Comment: 15 pages; accepted for publication in the European Physical Journal

Use of a new enrichment nanosorbent for speciation of mercury by FI-CV-ICP-MS

Mercury is one of the most toxic environmental pollutants and its effects on human and ecosystem health are well known. All mercury species are toxic, with organic mercury compounds generally being more toxic than inorganic species. Chromatography techniques (GC, HPLC) coupled to element specific detectors, are able to separate mercury species in order to elucidate mercury transformation and transport processes where the determination of all mercury species is desirable. However, in practice, especially in sampling campaigns for sea water analysis where a large number of samples are collected over a longer period of time, a combination of methods is usually applied to accurately determine the most toxic mercury species. These include non-chromatographic methods based on the different chemical and/or physical behavior of the mercury species. These non-chromatographic methods can be less time consuming, more cost effective and available, and present competitive limits of detection. Especially when mercury could vapor (CV) generation technique is employed, which reduces salt effect on the analytical signal and improve the sensibility. Among non-chromatographic methods, solid phase extraction and microextraction (SPE and SPME) which is becoming increasingly popular for sample preparation in organic analysis, found its way to speciation analysis of organometals. SPE/SPME is the most popular sample preconcentration method for its simplicity, high enrichment factor, low or no consumption of organic solvents and feasibly to be automated. On the other hand, the exploration of new materials, especially nanometer sized materials, as the support phase is another active research area in SPE/SPME for mercury determination. The use of nanoparticles leads to higher extraction capacity/efficiency and rapid dynamics of extraction originated from the higher surface area to volume ratio and short diffusion route. In this work, a new enrichment nanosorbent functionalized with 1,5 bis (2-pyridyl) methylene thiocarbohidrazide was synthesized and characterized. From the study of its adsorption capacity toward metal ions, Hg2+ was observed to be one of the most retained 173.1 µmol g-1 at pH 5. Thus, a flow injection solid phase extraction and cold vapor generation method for its determination and speciation based on the use of this new chelating nanosorbent was optimized. The method developed has showed to be useful for the automatic pre-concentration and sequential speciation of mercury and methylmercury in environmental and biological samples. The system was based on chelating retention of the analytes onto a mini-column filled with the new nanosorbent and their sequential elution by using two different eluents, 0.2 % HCl for CH3Hg+ and 0.1 % thiourea in 0.5 % HCl for Hg2+. The determination was performed using inductively coupled plasma mass spectrometry. Under the optimum conditions and 120 s preconcentration time, the enrichment factors were 4.7 and 11.0; the detection limits (3σ) were 0.002 and 0.004 µg L-1; the determination limits (10σ) were 0.011 and 0.024 µg L-1; and the precisions (calculated for 10 replicate determinations at a 2 µg L-1 standard of both species) were 2.8 and 2.6 % (RSD); for CH3Hg+ and Hg2+, respectively. Linear calibration graphs were obtained for both species from the determination limits to at least 70 µg L-1. For the quality control of the analytical performance and the validation of the newly developed method, the analysis of two certified samples, LGC 6016 estuarine water and SRM 2976 mussel tissue were addressed. The results showed good agreement with the certified values. The method was successfully applied to the speciation of mercury in sea-water samples collected in the Málaga Bay.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Influence of temperature and time on the Eu3+ reaction with synthetic Na-Mica-n (n = 2 and 4)

Bentonite is accepted as the best clay material for the engineered barrier of Deep Geological Repositories (DGRs). The performance of clay as the main component of the engineered barrier in the DGR has been intensively studied and the structure of the selected clay mineral play a crucial role. In this sense, a new family of synthetic swelling silicates, Na-Mica-n, with tuned layer charge (n) values between 2.0 and 4.0 per unit cell has recently been synthesized and a general synthetic method has been reported. These swelling high-charge micas could be highly valuable for the decontamination of harmful cations. The ability of these micas to immobilize Eu3+ under subcritical conditions has been probed. The adsorption was in both non-specific sites (cation exchange mechanism) and specific sites (chemical reaction or surface defects adsorption). Moreover, its adsorption capacity, under the same conditions is higher than in saponite and far superior to the bentonites.Junta de Andalucía P12-FQM-567European Union 29178

Advanced titanium scaffolds obtained by directional freeze-drying: on the influence of processing conditions

Ministry of Science and Innovation of Spain under Grant No. MAT2010-20855Junta de Andalucía (Spain) / FEDER (EU), through the project Ref. P12-TEP-140

Consideraciones sobre el auge de la franquicia como sistema de negocio en México

La franquicia es un sistema de negocio que se encuentra en auge debido al incremento, tanto del número de empresas franquiciadas como de los puntos de venta de las franquicias existentes en México. Es por esto que la presente investigación se enfoca en resaltar aquellos aspectos de la franquicia que, desde el enfoque de las teorías de la agencia, la teoría de los derechos de propiedad y la teoría de los costos de transacción, son consideradas relevantes ya que en los últimos años han hecho de la franquicia un sistema de negocio sobresaliente. Se retoman aspectos clave basados en investigaciones previas.Franchising is a business system that is booming due to the increase in both the number of franchised businesses and points of sales of existing franchises in Mexico. That is why this research is focused on highlighting those aspects of the franchise, from the perspective of agency theory, of property rights and the theory of transaction costs are considered relevant as they have made it an outstanding business system in recent years. Key aspects based on previous research are taken up

Synthesis and characterization of a new nanosorbent based on functionalized magnetic nanoparticles and its use in the determination of mercury by FI-CV-ETAAS

In this work, a new chelating sorbent which employs 1,5-bis(di-2-pyridil)methylene thiocarbohydrazide as the functional group and magnetic nanoparticles (MNPs) as its support (DPTH-MNP) was synthetized and characterized. The MNPs were prepared by coprecipitation of Fe+2 and Fe+3 with NH3 and then coated with silica in order to easily bind the support and the functionalizing molecule. The aim of the synthesis of this material is applying it as a solid-phase extracting agent and evaluating its potential for the extraction and pre-concentration of trace amounts of analytes present in biological and environmental samples with on-line methods. The MNPs’ magnetic core would allow overcoming the usual backpressure problems that happen in solid-phase extraction methods thanks to the possibility of immobilizing the MNPs by applying an external magnetic field. From the study of its adsorption capacity toward metal ions, mercury and antimony were the most retained. Thus, a flow injection solid phase extraction and cold vapor generation method for mercury determination based on the use of this new chelating nanosorbent was optimized. The greatest efforts were put into the reactor design to minimize compaction and loss of nanosorbent. The knotted reactor shown in Figure 1 was chosen as the best. Then, chemical and flow variables were optimized by Central composite designs (CCDs). The method developed has showed to be useful for the automatic pre-concentration and determination of mercury in environmental and biological samples. The determination was performed using electrothermal atomic absorption spectrometry (ETAAS). Under the optimum conditions, pH 5 and 120 s preconcentration time, the enrichment factor was 5.33; the detection limit (3σ) was 7.8 ng L-1; the determination limit (10σ) was 99 ng L-1; and the precisions (calculated for 10 replicate determinations at a 1 and 5 µg L-1 standards) were 1.7 and 1.9 % (RSD), respectively. Two linear calibration graphs were obtained, from the determination limits to 10 µg L-1 and from 10 to at least 50 µg L-1. From the comparison with other similar methods found in the bibliography, the detection limit and precisions calculated with our method were better. In order to evaluate the accurate and applicability of the method, the analysis of five certified samples LGC 6016 estuarine water, TMDA 54.4 fortified lake water, SRM 2976 mussel tissue, TORT-1 lobster hepatopancreas and DOLT-1 dogfish liver by standard addition and external calibration, were addressed. The results showed good agreement between the certified values, or added amounts of mercury, and the found concentrations. The method was successfully applied to the determination of mercury in sea-water samples collected in the Málaga Bay.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec