Design of a Coiled-Coil-based Model Peptide System toExplore the Fundamentals of Amyloid Fibril Formation

Protein deposition as amyloid fibrils underlies more than twenty severely debilitating human disorders. Interestingly, recent studies suggest that all peptides and proteins possess an intrinsic ability to assemble into amyloid fibrils similar to those observed in disease states. The common properties and characteristics of amyloid aggregates thus offer the prospect that simple model systems can be used to systematically assess the factors that predispose a native protein to form amyloid fibrils and understand the origin and progression of fatal disorders associated with amyloid formation. Here, we report the de novo design of a 17-residue peptide model system, referred to as ccβ, which forms a protein-like coiled-coil structure under ambient solution conditions but can be easily converted into amyloid fibrils by raising the temperature. Oxidation of methionine residues at selected hydrophobic positions completely abolished amyloid fibril formation of the peptide while not interfering with its coiled-coil structure. This finding indicates that a small number of site-specific hydrophobic interactions can play a major role in the packing of polypeptide chain segments within amyloid fibrils. The simplicity and characteristics of the ccβ system make it highly suitable for probing molecular details of the assembly of amyloid structure

Determinación de iones cloruro y sulfato en un mismo captador en investigaciones de corrosión atmosférica

Diferentes investigadores han reconocido la necesidad de continuar estudios sobre la influencia de los contaminantes atmosféricos, iones cloruro y sulfato, en la velocidad de corrosión. Ello puede estar asociado con la utilización de diferentes métodos de captación, específicos para uno u otro contaminante, cuando en la realidad ambos provienen principalmente de una fuente común, el aerosol marino, en atmósferas bajo su influencia. Fue objetivo de la presente investigación, demostrar la influencia que tiene la determinación de iones cloruro y sulfato en captadores diferentes o en un mismo captador en los resultados que se obtengan en las correlaciones de las velocidades de deposición de iones cloruro y sulfato y de estos con la velocidad de corrosión. En el estudio se emplea el método de la filtracita, de la vela seca y de la vela húmeda para la captación de iones cloruro y sulfato de forma conjunta, no así en las normas internacionales. La velocidad de deposición de iones cloruro y compuestos de azufre se determinó por un método volumétrico en presencia de un indicador mixto y por un método turbidimétrico, respectivamente. Para el procesamiento de los datos experimentales se utilizaron los paquetes de programas Microsoft Excel y STATGRAPHICS 6.1 para Windows. Como resultado del trabajo se demostró que existen diferencias significativas entre las velocidades de deposición, tanto para iones cloruro como sulfato entre captadores y se obtienen correlaciones cuando ambos contaminantes se determinan de manera conjunta en un mismo captador

The variational principle in transformation optics engineering and some applications

Transformation optics specializes in the engineering of advanced optical devices, and in combination with differential geometry it allows to control electromagnetic fields with artificial media in an unprecedented manner. In this work, we model transformation optics in an inherently covariant fashion starting with a fundamental Lagrangian function. As an application, we present the construction of a flat reflectionless immersion lens whose superior performance is important to applications in bio- and nano-technology.This work has been supported by the Spanish Ministerio de Ciencia e Innovacion under the grant MTM2009-08587, contract CSD2008-00066, and the FPU programme.García Meca, C.; Tung, MM. (2013). The variational principle in transformation optics engineering and some applications. Mathematical and Computer Modelling. 57(7):1773-1779. https://doi.org/10.1016/j.mcm.2011.11.035S1773177957

Implementación de medidas de eficiencia energética para la construcción factible de un refrigerador comercial con suministro de energía solar fotovoltaica

The high energy consumption of refrigerators and an intermittent power supply increase the electric bill cost and affect refrigerated products, respectively. This is the opinion of several shopkeepers who purchase this equipment for commercial activities. These problems are of concern to the manufacturer, which considers that the supply of its equipment could be affected. This article aims to build a more energy-efficient commercial refrigerator supplied with solar photovoltaic energy. The development begins with an energy balance of a conventional refrigerator to identify possible energy improvements. Subsequently, four measures are implemented to construct a refrigerator with higher energy performance and a solar photovoltaic installation, which provides reliable electricity. It is concluded that, through timely energy management, it is technically and economically feasible to build efficient refrigerators that operate with clean and renewable energy.El alto consumo energético de los refrigeradores y un suministro eléctrico intermitente incrementa el costo de la factura eléctrica y afecta los productos refrigerados, respectivamente. Así lo manifiestan diversos tenderos que adquieren estos equipos para actividad comercial. Estos inconvenientes preocupan al fabricante, que considera que la oferta de sus equipos podría afectarse. El objetivo de este artículo es construir un refrigerador comercial de mayor eficiencia energética, abastecido con energía solar fotovoltaica. El desarrollo inicia con un balance energético de un refrigerador convencional, para identificar posibles mejoras energéticas. Posteriormente, se implementan cuatro medidas que permiten la construcción de un refrigerador con mayor desempeño energético y una instalación solar fotovoltaica, que provee electricidad confiable. Se concluye que, mediante una oportuna gestión energética, es factible técnica y económicamente la construcción de refrigeradores eficientes que operen con energía limpia y renovable

Implementación de medidas de eficiencia energética para la construcción factible de un refrigerador comercial con suministro de energía solar fotovoltaica

El alto consumo energético de los refrigeradores y un suministro eléctrico intermitente incrementa el costo de la factura eléctrica y afecta los productos refrigerados, respectivamente. Así lo manifiestan diversos tenderos que adquieren estos equipos para actividad comercial. Estos inconvenientes preocupan al fabricante, que considera que la oferta de sus equipos podría afectarse. El objetivo de este artículo es construir un refrigerador comercial de mayor eficiencia energética, abastecido con energía solar fotovoltaica. El desarrollo inicia con un balance energético de un refrigerador convencional, para identificar posibles mejoras energéticas. Posteriormente, se implementan cuatro medidas que permiten la construcción de un refrigerador con mayor desempeño energético y una instalación solar fotovoltaica, que provee electricidad confiable. Se concluye que, mediante una oportuna gestión energética, es factible técnica y económicamente la construcción de refrigeradores eficientes que operen con energía limpia y renovable

Role of weak C—H…O and strong N—H…O inter­molecular inter­actions on the high-symmetry mol­ecular packing of trans-cyclo­hexane-1,4-dicarboxamide

An unpredicted fourfold screw N—H.O hydrogen bond C(4) motif in a primary dicarboxamide (trans-cyclo­hexane-1,4-dicarboxamide, C8H14N2O2) was investigated by single-crystal X-ray diffraction and IR and Raman spectroscopies. Electron-density topology and inter­molecular energy analyses determined from ab initio calculations were employed to examine the influence of weak C—H.O hydrogen-bond inter­actions on the peculiar arrangement of mol­ecules in the tetra­gonal P43212 space group. In addition, the way in which the co-operative effects of those weak bonds might modify their relative influence on mol­ecular packing was estimated from cluster calculations. Based on the results, a structural model is proposed which helps to rationalize the unusual fourfold screw mol­ecular arrangement.Instituto de Física La PlataCentro de Química InorgánicaFacultad de Ingenierí

Role of weak C—H…O and strong N—H…O inter­molecular inter­actions on the high-symmetry mol­ecular packing of trans-cyclo­hexane-1,4-dicarboxamide

An unpredicted fourfold screw N—H.O hydrogen bond C(4) motif in a primary dicarboxamide (trans-cyclo­hexane-1,4-dicarboxamide, C8H14N2O2) was investigated by single-crystal X-ray diffraction and IR and Raman spectroscopies. Electron-density topology and inter­molecular energy analyses determined from ab initio calculations were employed to examine the influence of weak C—H.O hydrogen-bond inter­actions on the peculiar arrangement of mol­ecules in the tetra­gonal P43212 space group. In addition, the way in which the co-operative effects of those weak bonds might modify their relative influence on mol­ecular packing was estimated from cluster calculations. Based on the results, a structural model is proposed which helps to rationalize the unusual fourfold screw mol­ecular arrangement.Instituto de Física La PlataCentro de Química InorgánicaFacultad de Ingenierí

Riesgo aumentado del desarrollo de un segundo melanoma cutáneo primario sobre un nevo en pacientes diagnosticados previamente de melanoma cutáneo primario sobre nevo

Es van analitzar les característiques de 981 malalts diagnosticats de melanoma cutani, dels quals 47 havien desenvolupat un segon melanoma. L'edat inferior a 40 anys, la localització en el tronc i el subtipus histològic d'extensió superficial, van ser factors de risc independents per al desenvolupament d'un primer melanoma sobre nevo. L'únic factor que es va associar al desenvolupament d'un segon melanoma sobre nevo, va ser que el primer també haguera mostrat esta associació. Estes troballes recalquen la importància preventiva de la vigilància dels nevos en malalts amb melanoma, sobretot quan este es desenvolupa sobre un nevo.Se analizaron las características de 981 pacientes diagnosticados de melanoma cutáneo, de los cuales 47 habían desarrollado un segundo melanoma. La edad inferior a 40 años, la localización en el tronco y el subtipo histológico de extensión superficial, fueron factores de riesgo independientes para el desarrollo de un primer melanoma sobre nevo. El único factor que se asoció al desarrollo de un segundo melanoma sobre nevo, fue que el primero también hubiera mostrado esta asociación. Estos hallazgos recalcan la importancia preventiva de la vigilancia de los nevos en pacientes con melanoma, sobre todo cuando este se desarrolla sobre un nevo

Ancient xenocrystic zircon in young volcanic rocks of the southern Lesser Antilles island arc

The Lesser Antilles arc is one of the best global examples in which to examine the effects of the involvement of subducted sediment and crustal assimilation in the generation of arc crust. Most of the zircon recovered in our study of igneous and volcaniclastic rocks from Grenada and Carriacou (part of the Grenadines chain) is younger than 2 Ma. Within some late Paleogene to Neogene (~ 34–0.2 Ma) lavas and volcaniclastic sediments however, there are Paleozoic to Paleoarchean (~ 250–3469 Ma) xenocrysts, and Late Jurassic to Precambrian zircon (~ 158–2667 Ma) are found in beach and river sands. The trace element characteristics of zircon clearly differentiate between different types of magmas generated in the southern Lesser Antilles through time. The zircon population from the younger arc (Miocene, ~ 22–19 Ma, to Present) has minor negative Eu anomalies, well-defined positive Ce anomalies, and a marked enrichment in heavy rare earth elements (HREE), consistent with crystallization from very oxidized magmas in which Eu2 + was in low abundance. In contrast, zircon from the older arc (Eocene to mid-Oligocene, ~ 30–28 Ma) has two different REE patterns: 1) slight enrichment in the light (L)REE, small to absent Ce anomalies, and negative Eu anomalies and 2) enriched High (H)REE, positive Ce anomalies and negative Eu anomalies (a similar pattern is observed in the xenocrystic zircon population). The combination of positive Ce and negative Eu anomalies in the zircon population of the older arc indicates crystallization from magmas that were variably, but considerably less oxidized than those of the younger arc. All the igneous zircon has positive εHf(t), reflecting derivation from a predominantly juvenile mantle source. However, the εHf(t) values vary significantly within samples, reflecting considerable Hf isotopic heterogeneity in the source. The presence of xenocrystic zircon in the southern Lesser Antilles is evidence for the assimilation of intra-arc crustal sediments and/or the recycling and incorporation of sediments into the magma sources in the mantle wedge. Most likely however, primitive magmas stalling and fractionating during their ascent through the Antilles crust entrained ancient zircon. This is evidence by the geochemistry of the study samples, which is inconsistent with any involvement of partially melted subducted sediment. Paleogeographic reconstructions show that the old zircon could derive from distant regions such as the Eastern Andean Cordillera of Colombia, the Merida Andes, and the northern Venezuela coastal ranges, transported for example by the Proto-Maracaibo River precursor of the Orinoco River.This study was supported by Deutsche Forschungsgemeinschaft (DFG) grants KR590/85-1 to AK and RO4174/2-1 to YRA, and Spanish MINECO grants CGL2015-65824 and CGL2012-36263 and University of Granada research program (CIC) to AGC and CLC. This research also received support from the SYNTHESYS Project (http://www.synthesys.info/) which is financed by the European Community Research Infrastructure Action under the FP7 “Capacities” Program, the Intra-University Research Support Program of Mainz University (Universitätsinterne Forschungsförderung (FoFö)

Ancient xenocrystic zircon in young volcanic rocks of the southern Lesser Antilles island arc

The Lesser Antilles arc is one of the best global examples in which to examine the effects of the involvement of subducted sediment and crustal assimilation in the generation of arc crust. Most of the zircon recovered in our study of igneous and volcaniclastic rocks from Grenada and Carriacou (part of the Grenadines chain) is younger than 2 Ma. Within some late Paleogene to Neogene (~ 34¿0.2 Ma) lavas and volcaniclastic sediments however, there are Paleozoic to Paleoarchean (~ 250¿3469 Ma) xenocrysts, and Late Jurassic to Precambrian zircon (~ 158¿2667 Ma) are found in beach and river sands. The trace element characteristics of zircon clearly differentiate between different types of magmas generated in the southern Lesser Antilles through time. The zircon population from the younger arc (Miocene, ~ 22¿19 Ma, to Present) has minor negative Eu anomalies, well-defined positive Ce anomalies, and a marked enrichment in heavy rare earth elements (HREE), consistent with crystallization from very oxidized magmas in which Eu2 + was in low abundance. In contrast, zircon from the older arc (Eocene to mid-Oligocene, ~ 30¿28 Ma) has two different REE patterns: 1) slight enrichment in the light (L)REE, small to absent Ce anomalies, and negative Eu anomalies and 2) enriched High (H)REE, positive Ce anomalies and negative Eu anomalies (a similar pattern is observed in the xenocrystic zircon population). The combination of positive Ce and negative Eu anomalies in the zircon population of the older arc indicates crystallization from magmas that were variably, but considerably less oxidized than those of the younger arc. All the igneous zircon has positive ¿Hf(t), reflecting derivation from a predominantly juvenile mantle source. However, the ¿Hf(t) values vary significantly within samples, reflecting considerable Hf isotopic heterogeneity in the source. The presence of xenocrystic zircon in the southern Lesser Antilles is evidence for the assimilation of intra-arc crustal sediments and/or the recycling and incorporation of sediments into the magma sources in the mantle wedge. Most likely however, primitive magmas stalling and fractionating during their ascent through the Antilles crust entrained ancient zircon. This is evidence by the geochemistry of the study samples, which is inconsistent with any involvement of partially melted subducted sediment. Paleogeographic reconstructions show that the old zircon could derive from distant regions such as the Eastern Andean Cordillera of Colombia, the Merida Andes, and the northern Venezuela coastal ranges, transported for example by the Proto-Maracaibo River precursor of the Orinoco River.YRA thanks Bob Stern for suggesting fieldwork in Grenada to “hunt” for old zircons” and Jesús Máximo and Kathrin Abraham for help and support during fieldwork. Liqin Zhou and Xiao-Chao Che provided the zircon CL images, Chun Yang prepared perfect zircon mounts, and Jianhui Liu and Zhiqing Yang made sure that the SHRIMP II instrument in Beijing was in excellent operating condition. Jianfeng Gao of Nanjing University provided an unpublished Excel-based program to construct the Hf evolution diagrams of Fig. 10 . This study was supported by Deutsche Forschungsgemeinschaft (DFG) grants KR590/85-1 to AK and RO4174/2-1 to YRA, and Spanish MINECO grants CGL2015-65824 and CGL2012-36263 and University of Granada research program (CIC) to AGC and CLC. This research also received support from the SYNTHESYS Project ( http://www.synthesys.info /) which is financed by the European Community Research Infrastructure Action under the FP7 “Capacities” Program, the Intra-University Research Support Program of Mainz University (Universitätsinterne Forschungsförderung (FoFö). We thank two anonymous reviewers who helped to improve the manuscript and Prof. Sun (editor of LITHOS) for handling our publication