Synthesis and characterization of new aromatic polyamides bearing crown ethers and acyclic ethylene oxide units in the pendant structure. III. Benzo-18-crown-6 systems and their open-chain counterparts

We report the synthesis and characterization of 10 novel polyamides containing the benzo-18-crown-6 subunit and its dipodal counterpart, along with their properties, and a comparison with homologous polyamides bearing benzo-12-crown-4, benzo-15-crown-5, and the corresponding dipodal systems. The anomalous polymerization of some of the diacid monomers, that leads to insoluble gels under standard Yamazaki polymerization conditions, is described. The gel formation has been attributed to the threading of cyclic oligoamides with a growing polyamide chain to yield rotaxanes, polyrotaxanes, catenanes, or polycatenanes. Polyamide macrocycles have been characterized with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. A route to avoid gel formation, consisting of a lower initial monomer concentration, is also described, along with the polymer properties of the polyamides obtained, including the chemical characterization, mechanical behavior, water sorption, morphology, diffusion data, and permeability of membranes prepared with these polymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6252-6269, 200

Mapa de exposición internacional de la economía española

Este estudio analiza los niveles de interdependencia y riesgo que se dan en las relaciones económicas entre España y un gran número de países. Para ello se utilizan datos bilaterales sobre vínculos comerciales y financieros de España con el resto del mundo para construir, mediante el análisis de componentes principales, un índice de interdependencia de España con cada país. Asimismo, la agregación mediante la misma técnica de diversas medidas de riesgo, como las calificaciones crediticias soberanas y otras más genéricas, permite construir un índice de riesgo para cada país. Combinando la información de ambos índices, se encuentra que las mayores interdependencias de la economía española se dan con países asociados a niveles reducidos de riesgo (esencialmente países de la OCDE), mientras que las principales interdependencias asociadas a niveles intermedios de riesgo se dan en relación a países de América Latina y países exportadores de productos energético

Evolution induced by dry minor mergers onto fast-rotator S0 galaxies

We analysed collisionless N-body simulations of intermediate and minor dry mergers onto S0s to test whether these mergers can generate S0 galaxies with kinematics intermediate between fast and slow rotators. We find that minor mergers induce a lower decrease of the global rotational support than encounters of lower mass ratios, which results in S0s with properties intermediate between fast and slow rotators. The resulting remnants are intrinsically more triaxial, less flattened, and span the whole range of apparent ellipticities up to $\epsilon_\mathrm{e} \sim 0.8$. They do not show lower apparent ellipticities in random projections than initially; on the contrary, the formation of oval distortions and the disc thickening increase the percentage of projections at $0.4 < \epsilon_\mathrm{e} < 0.7$. In the experiments with S0b progenitor galaxies, minor mergers tend to spin up the bulge and to decrease slightly its intrinsic ellipticity, whereas in the cases of primary S0c galaxies they keep the rotational support of the bulge nearly constant and decrease significantly its intrinsic ellipticity. The remnant bulges remain nearly spherical ($B/A \sim C/A > 0.9$), but exhibit a wide range of triaxialities ($0.20 < T < 1.00$). In the plane of global anisotropy of velocities ($\delta$) vs. intrinsic ellipticity ($\epsilon_\mathrm{e,intr}$), some of our models extend the linear trend found in previous major merger simulations towards higher $\epsilon_\mathrm{e,intr}$ values, while others depart from it. This is consistent with the wide dispersion exhibited by real S0s in this diagram compared with ellipticals, which follow the linear trend drawn by major merger simulations. The different trends exhibited by ellipticals and S0 galaxies in the $\delta$ - $\epsilon_\mathrm{e}$ diagram may be pointing to the different role played by major mergers in the build-up of each morphological type.Comment: Corrected typos. 20 pages, 14 figures. Accepted for publishing in A&

Evaluación continuada automática de Fundamentos de Programación en C

En este trabajo se describe el uso de un sistema de evaluación automática como herramienta de apoyo para el aprendizaje y seguimiento continuado de los alumnos de la asignatura de Fundamentos de Programación del primer curso de las titulaciones de los grados de Ingeniería en Tecnologías Industriales y de Ingeniería Química impartidos en la Escuela Técnica Superior de Ingenieros Industriales de la Universidad Politécnica de Madrid (ETSII-UPM) desde el curso 2010-11. El sistema de evaluación se implementa mediante uno de los módulos de la plataforma AulaWeb desarrollada en la UPM. Se analizan además los resultados obtenidos considerando que las calificaciones obtenidas en los ejercicios programados pueden tenerse en cuenta en la calificación final de la asignatura como parte de la evaluación continuada durante el periodo académico de acuerdo con la metodología propuesta en el Proceso de Bolonia para los estudios universitarios

Caracterización estructural del sistema ovino-caprino de la región noroeste de República Dominicana (Structural characterization of sheep and goat farming systems in Northwest Dominican Republic)

The aim of this study was to analyze structural aspects of goat and ovine livestock farming systems located in the Norwest of Dominican Republic. The sample (94 farms) was randomly selected with proportional allocation by region. Forty-four variables related to structural and productive aspects were analyzed. The average size of farms was 96 ha and 165 animals. Their facilities are simple, nonspecific and barely functional, with a mean of 2 pens per farm. Farms generally do not have perimeter fences, facilities for breeding, feeding or watering points. The reproductive strategy is the natural breeding throughout the year on most farms, with a ratio of one sire for every 36 females, and there are no breeding records. The first mating takes place with an average weight of 17 kg at 6.5 months of age. Feeding is based on grazing of natural pastures and forests (94%), reaching a stocking density of 0.83 LU/ha. Food supplementation is used in 37% of farms, mainly in sheep and mixed farms. The lambs and goats are sold when they reach 23 kg in weight, around 7 months of age. The farms do not receive technical advice, although 94% of them apply preventive treatments on a regular basis. The mortality rate reached 12%. In general, farms are very heterogeneous in their production structure, management, nutrition and health. Thus, a group of farms developed a traditional system (goats), while the most efficient and technified correspond to sheep and mixed farms

Quality of cherry ‘Sweetheart’ from different regions of Portugal and Spain (Cova da Beira, Portalegre and Valle del Jerte).

Sweet cherries (Prunus avium L.) ‘Sweetheart’ were harvested at different production regions from Portugal (Cova da Beira and Portalegre) and Spain (Valle de Jerte). Cherries were harvested at their commercial maturation according to the empirical knowledge of external color corresponding to good quality. Fruits were stored and evaluated in order to study their quality on the harvest day and during a period of 21 days, at cold storage (1 ºC, 95% RH). The sweet cherry ‘Sweetheart’ is a well known variety and a highly appreciated one but fruits present a short shelf life. On the other hand the effect of different “terroir” on cherry characteristics should be known and clarified. Fruits from day 0, considered without storage, were kept at 20ºC and analyzed. Every weak, 3 replicas were randomly picked up and 10 fruits from each one were submitted to several analyses after fruit temperature stabilized at 20ºC. Several quality parameters were evaluated: external color (L*, a*, b*), texture, soluble solids content (SSC), titratable acidity (TA) and the ratio between soluble solid contents (SSC) and tritratable acidity (TA). Fruits from different orchards and locations were significantly different according to these parameters. Fruits from Cova da Beira were less firm comparing with other two regions, Valle de Jerte and Portalegre, which may indicate a higher maturation rate at harvest in those fruits. This is in accordance with SSC/titratable acidity rate suggesting a late harvest in Cova da Beira comparing with other two orchards, however fruits from Cova da Beira exhibit a poor color at harvest. These results clearly showed a lower correlation between SSC and firmness considering fruits origin