214 research outputs found
Sobre elefants voladors i altres prodigis : comentaris entorn del Premi Nobel de Química 2002
Steornomy of a ribbed vault in Santa María Cathedral of Cuenca
La Catedral de Santa María de Cuenca es uno de los edificios más emblemáticos la ciudad, declarada Patrimonio de la Humanidad por la Unesco en 1996. Las múltiples alteraciones que el edificio ha sufrido a lo largo de los siglos dificultan mucho su comprensión. En este trabajo se constatan estas modificaciones mediante el estudio de una bóveda cuatripartita de crucería, donde se mezclan el estilo gótico con el renacentista. Para ello mediante un levantamiento planimétrico y despiece de la basa de sus pilares, de sus arcos apuntados, perpiaños y cruceros, de su clave e incluso de la plementería se ha podido entender la estereotomía de la bóveda a partir de la modelización en 3D de dicha bóveda construida íntegramente en piedra
Wide-scope screening of pharmaceuticals, illicit drugs and their metabolites in the Amazon River
Only a limited number of households in the Amazon are served by sewage collection or treatment facili- ties, suggesting that there might be a significant emission of pharmaceuticals and other wastewater contaminants into freshwater ecosystems. In this work, we performed a wide-scope screening to assess the occurrence of pharmaceuticals, illicit drugs and their metabolites in freshwater ecosystems of the Brazilian Amazon. Our study included 40 samples taken along the Amazon River, in three of its major tributaries, and in small tributaries crossing four important urban areas (Manaus, Santarém, Macapá, Belém). More than 900 compounds were investigated making use of target and suspect screening approaches, based on liquid chromatography coupled to high-resolution mass spectrometry with ion mobility separation. Empirical collision-cross section (CCS) values were used to help and confirm identifications in target screening, while in the suspect screening approach CCS values were predicted using Artificial Neural Networks to increase the confidence of the tentative identification. In this way, 51 compounds and metabolites were identified. The highest prevalence was found in streams crossing the urban areas of Manaus, Macapáand Belém, with some samples containing up to 30 - 40 compounds, while samples taken in Santarém showed a lower number (8 - 11), and the samples taken in the main course of the Amazon River and its tributaries contained between 1 and 7 compounds. Most compounds identified in areas with significant urban impact belonged to the analgesics and antihypertensive categories, followed by stimulants and antibiotics. Compounds such as caffeine, cocaine and its metabolite benzoylecgonine, and cotinine (the metabolite of nicotine), were also detected in areas with relatively low anthropogenic impact and showed the highest total prevalence. This study supports the need to improve the sanitation system of urban areas in the Brazilian Amazon and the development of follow-up studies aimed at quantifying exposure levels and risks for Amazonian freshwater biodiversity
Mineralogy and distribution of critical elements in the Sn–W–Pb–Ag–Zn Huanuni deposit, Bolivia
The polymetallic Huanuni deposit, a world-class tin deposit, is part of the Bolivian tin belt. As a likely case for a “mesothermal” or transitional deposit between epithermal and porphyry Sn types (or shallow porphyry Sn), it represents a case that contributes significantly to the systematic study of the distribution of critical elements within the “family” of Bolivian tin deposits. In addition to Sn, Zn and Ag, further economic interest in the area resides in its potential in critical elements such as In, Ga and Ge. This paper provides the first systematic characterisation of the complex mineralogy and mineral chemistry of the Huanuni deposit with the twofold aim of identifying the mineral carriers of critical elements and endeavouring plausible metallogenic processes for the formation of this deposit, by means of a multi-methodological approach. With In concentrations consistently over 2000 ppm, the highest potential for relevant concentrations in this metal resides in widespread tin minerals (cassiterite and stannite) and sphalerite. Hypogene alteration assemblages are hardly developed due to the metasedimentary nature of host rocks, but the occurrence of potassium feldspar, schorl, pyrophyllite and dickite as vein material stand for potassic to phyllic or advanced argillic alteration assemblages and relatively high-temperature (and low pH) mineralising fluids. District-scale mineralogical zonation suggests a thermal zonation with decreasing temperatures from the central to the peripheral areas. A district-scale zonation has been also determined for d34SVCDT values, which range -7.2‰ to 0.2‰ (mostly -7‰ to -5‰) in the central area and -4.2‰ to 1.0‰ (mainly constrained between -2‰ and 1‰) in peripheral areas. Such values stand for magmatic and metasedimentary sources for sulfur, and their spatial zoning may be related to differential reactivity between mineralising fluids and host rocks, outwardly decreasing from the central to the peripheral areasPeer ReviewedPostprint (published version
Examining Topoisomers of a Snake-Venom-Derived Peptide for Improved Antimicrobial and Antitumoral Properties
Ctn[15-34], the C-terminal section of crotalicidin (Ctn), a cathelicidin from a South American pit viper, is an antimicrobial and antitumoral peptide with remarkably longer stability in human serum than the parent Ctn. In this work, a set of topoisomers of both Ctn and Ctn[15-34], including the retro, enantio, and retroenantio versions, were synthesized and tested to investigate the structural requirements for activity. All topoisomers were as active as the cognate sequences against Gram-negative bacteria and tumor cells while slightly more toxic towards normal cells. More importantly, the enhanced serum stability of the D-amino-acid-containing versions suggests that such topoisomers must be preferentially considered as future antimicrobial and anticancer peptide leads
Biogeographic, atmospheric, and climatic factors influencing tree growth in Mediterranean Aleppo pine forests
There is a lack of knowledge on how tree species respond to climatic constraintslike water shortages and related atmospheric patterns across broad spatial and temporal scales.These assessments are needed to project which populations will better tolerate or respond to globalwarming across the tree species distribution range. Warmer and drier conditions have been forecastedfor the Mediterranean Basin, where Aleppo pine (Pinus halepensisMill.) is the most widely distributedconifer in dry sites. This species shows plastic growth responses to climate, being particularly sensitiveto drought. We evaluated how 32 Aleppo pine forests responded to climate during the second half ofthe 20th century by using dendrochronology. Climatic constraints of radial growth were inferred byfitting the Vaganov-Shashkin (VS-Lite) growth model to ring-width data from our Aleppo pine forestnetwork. Our findings reported that Aleppo pine growth decreased and showed the highest commoncoherence among trees in dry, continental sites located in southeastern and eastern inland Spain andAlgeria. In contrast, growth increased in wetter sites located in northeastern Spain. Overall, across theAleppo pine network tree growth was enhanced by prior wet winters and cool and wet springs,whilst warm summers were associated with less growth. The relationships between site ring-widthchronologies were higher in nearby forests. This explains why Aleppo pine growth was distinctlylinked to indices of atmospheric circulation patterns depending on the geographical location of theforests. The western forests were more influenced by moisture and temperature conditions drivenby the Western Mediterranean Oscillation (WeMO) and the Northern Atlantic Oscillation (NAO),the southern forests by the East Atlantic (EA) and the august NAO, while the Balearic, Tunisian andnortheastern sites by the Arctic Oscillation (AO) and the Scandinavian pattern (SCA). The climaticconstraints for Aleppo pine tree growth and its biogeographical variability were well captured by theVS-Lite model. The model performed better in dry and continental sites, showing strong growthcoherence between trees and climatic limitations of growth. Further research using similar broad-scaleapproaches to climate-growth relationships in drought-prone regions deserves more attention
Functional and evolutionary analysis of DXL1, a non-essential gene encoding a 1-deoxy-D-xylulose 5-phosphate synthase like protein in Arabidopsis thaliana
The synthesis of 1-deoxy-D-xylulose 5-phosphate (DXP), catalyzed by the enzyme DXP synthase (DXS), represents a key regulatory step of the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway for isoprenoid biosynthesis. In plants DXS is encoded by small multigene families that can be classified into, at least, three specialized subfamilies. Arabidopsis thaliana contains three genes encoding proteins with similarity to DXS, including the well-known DXS1/CLA1 gene, which clusters within subfamily I. The remaining proteins, initially named DXS2 and DXS3, have not yet been characterized. Here we report the expression and functional analysis of A. thaliana DXS2. Unexpectedly, the expression of DXS2 failed to rescue Escherichia coli and A. thaliana mutants defective in DXS activity. Coherently, we found that DXS activity was negligible in vitro, being renamed as DXL1 following recent nomenclature recommendation. DXL1 is targeted to plastids as DXS1, but shows a distinct expression pattern. The phenotypic analysis of a DXL1 defective mutant revealed that the function of the encoded protein is not essential for growth and development. Evolutionary analyses indicated that DXL1 emerged from DXS1 through a recent duplication apparently specific of the Brassicaceae lineage. Divergent selective constraints would have affected a significant fraction of sites after diversification of the paralogues. Furthermore, amino acids subjected to divergent selection and likely critical for functional divergence through the acquisition of a novel, although not yet known, biochemical function, were identified. Our results provide with the first evidences of functional specialization at both the regulatory and biochemical level within the plant DXS family
Steornomy of a ribbed vault in Santa Maria Cathedral of Cuenca
[ES] La Catedral de Santa Maria de Cuenca es uno de los edificios más emblemáticos la ciudad, declarada Patrimonio de la Humanidad por la Unesco en 1996. Las múltiples alteraciones que el edificio ha sufrido a lo largo de los siglos dificultan mucho su comprensión.En este trabajo se constatan estas modificaciones mediante el estudio de una bóveda cuatripartita de crucería, donde se mezclan el estilo gótico con el renacentista.Para ello mediante un levantamiento planimétrico y despiece de la basa de sus pilares, de sus arcos apuntados, perpianos y cruceros, de su clave e incluso de la plementería se ha podido entender la estereotomía de la bóveda a partir de la modelización en 3D de dicha bóveda construida integramente en piedra.Torrero Fuentes, E.; Coronado Gómez, AM.; Canosa Mora, M.; Pérez Andreu, V.; Sanz Martínez, D. (2014). Estereotomía de una bóveda de crucería de la catedral de Cuenca. EGE Revista de Expresión Gráfica en la Edificación. 0(8):61-66. https://doi.org/10.4995/ege.2014.12484OJS61660
Diseño de la asignatura Trabajo Fin de Grado en Geología (Facultad de Ciencias, UA)
Con la implantación en el año académico 2013-14 del cuarto y último curso del grado en Geología en la Universidad de Alicante, se ha implementado la asignatura obligatoria de Trabajo Fin de Grado en Geología (TFGG) con el objetivo de que el estudiante demuestre las competencias adquiridas durante sus estudios de geología, tanto las específicas de la titulación, como las competencias generales o transversales, tal como son las ligadas a la búsqueda y organización de documentación, a la redacción clara y concisa de una memoria escrita que recoja un trabajo original del alumno y a la presentación en público de su trabajo de manera clara y adecuada. Siguiendo las directrices que se establecen, tanto en la Facultad de Ciencias, como en la Universidad de Alicante se ha diseñado una asignatura Trabajo Fin de Grado con varias modalidades o líneas de actividad docente. Se ha constituido una Comisión de Trabajo de Fin de Grado en Geología (CTFGG) con el propósito principal de organizar y supervisar la asignación, seguimiento y evaluación de los trabajos
Conformationally restricted PACAP27 analogues incorporating type II/II′ IBTM β-Turn mimetics. Synthesis, NMR structure determination, and binding affinity
To probe the importance of a proposed β-turn within residues S9-R12 of PACAP for recognition by VIP/PACAP receptors, compounds 1 and 2, two conformationally restricted analogues of PACAP27 incorporating respectively (S)- or (R)-IBTM as type II or II′ β-turn dipeptide mimetic at the Y10-S11 position, were synthesized. According to 1H NMR conformational analyses in aqueous solution and 30% TFE, both PACAP27 and the [S-IBTM10,11]PACAP27 analogue 1 adopt similar ordered structures. PACAP27 shows an N-terminal disordered region (residues H1-F6) and an α-helical conformation within segment T7–L27. For residues S9–R12, our data seem more compatible with a segment of the α-helix than with the β-turn previously proposed for this fragment. In compound 1 the α-helix, also spanning T7–L27 residues, appears slightly distorted at the N-terminus relative to the native peptide. Although this distortion could lead to the marked decrease in binding affinity of this compound at the VIP/PACAP receptors, the lack of the Y10 side chain in analogues 1 and 2 could also significantly affect the binding of these compounds.Work at the Instituto de Quı́mica Médica and Universidad de Navarra was supported by CICYT (SAF 97 0030 and SAF 2000-0147), Fundación La Caixa (97/022) and Comunidad Autónoma de Madrid (08.5/0006/1998). Work at the Instituto de Estructura de la Materia was supported by DGICYT (PB98-0677) and the European Union (CEE B104-97-2086). Work at the Universidad de Barcelona was supported by Generalitat de Catalunya (CERBA). C.M.S. and M.M.-M. are recipients of a pre-doctoral and a post-doctoral fellowship, respectively, from the Comunidad Autónoma de Madrid, Spain. E.de O. is a post-doctoral fellow of Fundació Bosch i Gimpera, Universitat de Barcelona, Spain
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