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

Oxidative stress in E. coli cells upon exposure to heat treatments

Heat treatments are widely used by the food industry to inactivate microorganisms, however their mode of action on microbial cells is not fully known. In the last years, it has been proposed that the generation of oxidative species could be an important factor contributing to cell death by heat and by other stresses; however, investigations in this field are scarce. The present work studies the generation of reactive oxygen species (ROS) upon heat treatment in E. coli, through the use of cell staining with specific fluorochromes. Results obtained demonstrate that ROS are detected in E. coli cells when they are subjected to heat exposure, and the amount of fluorescence increases with temperature and time, as does the cellular inactivation. The addition of glutathione or tiron, a potent antioxidant and a superoxide quencher, respectively, to the heating medium protected E. coli against heat inactivation and concurrently reduced the detection of ROS, especially in the case of glutathione. Finally, recovery of heated cells under conditions that relief oxidative stress produced an increase in cell survival. Data presented in this work support the view that ROS generation and subsequent control in bacterial cells could be an essential factor determining inactivation and survival upon exposure to heat, and it could be a potential target to increase the efficacy of current treatments

Catalytic hydroprocessing of lignin β-O-4 ether bond model compound phenethyl phenyl ether over ruthenium catalysts

The catalytic hydroprocessing of phenethyl phenyl ether (PPE), a model compound of one of the most significant ether linkages within lignin structure, β-O-4, has been studied. Reactions were carried out using two ruthenium-based catalysts, supported on different materials: 3.8 wt.% Ru/C and 3.9 wt.% Ru/Al2O3. Aiming at studying the reaction mechanism, experiments were carried out at 150 °C and 25 bar in H2 atmosphere, with varying feed to catalyst mass ratios and reaction time. Differences between the relative importance of the steps of the mechanism were observed when using those two catalysts. The most significant finding was the predominance of the cleavage of Cβ-O bonds compared to the cleavage of the Caryl-O when using Ru/Al2O3 as catalyst; whereas with Ru/C, the two routes were nearly equivalent. It has been observed that the kinetic model describes the general tendencies of consumption and formation of the different products, but some over/under estimation of concentrations occurs. Finally, the effect of temperature was also explored by carrying out reactions at 100 and 125 °C, observing that decreasing temperature from 150 to 125 or 100 °C favored the dimer hydrogenation route versus the hydrogenolysis of the ether bonds

Estudio morfométrico de las abejas andaluzas

The biological and behavioral characteristics of the iberian bees are much less known than the other european races. This paper studies the morphological characteristics (Proboscis length; Forewing length; Forewing width; Cubital vein a; Cubital vein b; Cubital index a/b; Hindwing length; Hindwing width; Femur length; Tibia length; Metatarsus length; Metatarsus width; Width of tomentum at tergite 4; Pigmentation of tergite 3) of bees used in andalusian apiculture. Our results coincide with those described for Apis mellifera iberica.Las características biológicas y de comportamiento que presentan las abejas de la península ibérica son menos conocidas que las que presentan otras razas europeas. En el presente trabajo estudiamos las características morfológicas (longitud de la proboscis; longitud del ala delantera derecha; anchura del ala delantera derecha; vena cubital a; vena cubital b; índice cubital a/b; longitud del ala trasera derecha; anchura del ala trasera derecha; longitud del fémur; longitud de la tibia; longitud del metatarso; anchura del metatarso; longitud del tomentun del terguito 4º y pigmentación del terguito 3º) que presentan las abejas empleadas en la apicultura andaluza. Nuestros resultados coinciden con los descritos para Apis mellifera iberica

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

Abejas, apicultura y el nuevo mundo

In the New World, some stingless bees were kept by the native population. In Central America, maya beekeepers worked with Mellipona beecheii, in Yucatan and adjacent regions. The arrival in North America of the first beehives was in 1691 and it were sent to Virginia by the Council of the Virginia Company in London. Concerning the introduction to Central and South America the first ones arrived from Spain and Portugal towards the end of the 18th century, probably to Brazil. Prior to 1800, the european breeds taken to America were probably Apis mellifera mellifera and Apis mellifera iberica. At the turn of the century, a new european breed was imported from Italy (Apis mellifera ligustica). American apiculture has used these breeds and crossbreeds virtually up to the present day. In 1956, tropical african queens of the breed Apis mellifera scutellata were introduced to Brazil. Its crosses involving european breeds gave rise to africanized bees, which have spread over almost the whole of South, Central and North America.Los nativos del Nuevo Mundo utilizaban algunas abejas sin aguijón. En América Central los apicultores mayas trabajaron, en el Yucatán y regiones adyacentes, con Mellipona beecheii. Los nativos del Nuevo Mundo utilizaban algunas abejas sin aguijón. En América Central los apicultores mayas trabajaron, en el Yucatán y regiones adyacentes, con Mellipona beecheii. La llegada a América del Norte de las primeras colmenas se produjo en 1691. Fueron enviadas a Virginia desde Inglaterra por la Virginia Company. Las primeras colmenas enviadas a América Central y del Sur, probablemente a Brasil, a finales del siglo XVIII, procedían de España y Portugal. Antes de 1800 las razas europeas llevadas a Amé-rica fueron, probablemente, Apis mellifera mellifera y Apis mellifera iberica. A fin de siglo se introduce otra (Apis mellifera ligustica) procedente de Italia. La apicultura americana ha empleado las razas mencionadas y sus cruces, hasta nuestros días. En 1956 se introdujeron en Brasil reinas de Apis mellifera scutellata, procedentes de Africa tropical. Las abejas procedentes de su cruce con razas europeas, “africanizadas”, se han extendido por casi la totalidad del continente americano