Simultaneous analysis of elastic scattering and transfer/breakup channels for the 6He+208Pb reaction at energies near the Coulomb barrier

The elastic and alpha-production channels for the 6He+208Pb reaction are investigated at energies around the Coulomb barrier (E_{lab}=14, 16, 18, 22, and 27 MeV). The effect of the two-neutron transfer channels on the elastic scattering has been studied within the Coupled-Reaction-Channels (CRC) method. We find that the explicit inclusion of these channels allows a simultaneous description of the elastic data and the inclusive alpha cross sections at backward angles. Three-body Continuum-Discretized Coupled-Channels (CDCC) calculations are found to reproduce the elastic data, but not the transfer/breakup data. The trivially-equivalent local polarization potential (TELP) derived from the CRC and CDCC calculations are found to explain the features found in previous phenomenological optical model calculations for this system.Comment: 7 pages, 6 figures (replaced with updated version

Utopian urbanism, dystopian realities. An (im)possible ethnography in Yachay, the city of knowledge

Described as the most important project in Ecuador’s history Yachay, meaning knowledge, in Kichwa, is an urban development initiative conceived as the bridge towards a society free from the dependent exploitation of nature. Embracing the current wave of optimism that surrounds open source platforms of information sharing, Yachay has been projected as new ‘knowledge haven’. This is the utopia of a new city which converts a society based on an extractive economy to one based on knowledge. The risk of pursuing this dream is ignoring the existing economic and political conditions but also the hopes to build a "new country" that brought the so-called Citizen Revolution. We wanted to think, reflect and learn about one of the most thrilling urban plans to have emerged in Latin America. This paper reports on frustrated attempts to conduct this research and interprets their eloquent silences and reluctance

Lorenz System Parameter Determination and Application to Break the Security of Two-channel Chaotic Cryptosystems

This paper describes how to determine the parameter values of the chaotic Lorenz system used in a two-channel cryptosystem. The geometrical properties of the Lorenz system are used firstly to reduce the parameter search space, then the parameters are exactly determined, directly from the ciphertext, through the minimization of the average jamming noise power created by the encryption process.Comment: 5 pages, 5 figures Preprint submitted to IEEE T. Cas II, revision of authors name spellin

Distinct complexing trends of chitosan with toxic metals (PO1-24)

We have been able to prove that not only adsorption but also complexation of different metals (Pb, Cd, Mo, Cu, Zn and Cr) actually takes place in acetate buffer (pH=4) with Chitosans of different molecular weights and deacetylation degrees. Depending on the different electrochemical behaviour on mercury electrode of studied metals and the nature of the resulting complexes, diverse approaches have been used. Chitosan molecular weight and concentration had been seen to play a key role in the Chitosan binding activity with Zn, Pb and Cd, as reported elsewhere[1]. Length of Chitosan chains influences the degree of complexation with both Cr and Mo, while Cu binding capacity remains independent of the molecular weight of the assayed polymers. The larger the polymer chain length the higher the number of amino group available for the retention of both Cr and Mo within the tridimensional structure of the acting ligand. This is consistent with a predominant intra-chain linkage of both metal atoms. On the contrary, in the case of Cu, an inter-layer binding mechanism is proposed as the main retention factor by Chitosan

Effect of chemical structure on the sonochemical degradation of perfluoroalkyl and polyfluoroalkyl substances (PFASs)

Perfluoroalkyl surfactants include chemicals characterized by a fully fluorinated carbon chain (hydrophobic and oleophobic tail) bound to a hydrophilic head (a carboxyl or sulfonic group). These compounds are toxic and highly resistant to chemical/biological attack, and some are known to be bio-accumulative. This study investigates the sonochemical degradation at 500 kHz of different carboxylic and sulfonic perfluoroalkyl and polyfluoroalkyl substances (PFASs, 1.7 mM total organic fluorine) to assess the effect of chain length, functional head group, and substituents (–CH2–CH2– moiety and ether group) on the degradation rate. Under these conditions, the rates of defluorination determined for two widely used perfluoroalkyl substances, perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), were 3.5 to 3.7 μM F− min−1, respectively. The degradation rate of perfluoroalkyl sulfonates decreased with the perfluorocarbon chain length as indicated by the 1.3 and 1.9-fold lower defluorination rates for perfluorohexane- and perfluorobutane sulfonate than that of PFOS. A similar trend was observed during the sonolysis of perfluoroalkyl carboxylate analogs with 6, 5 or 3 carbon atoms which had 1.1-, 1.8-, and 2.3-fold lower defluorination rates, respectively, than that of PFOA. Furthermore, perfluoroalkyl compounds appeared more amenable to sonolysis than the polyfluoroalkyl analogues with the same number of C atoms (defluorination rate of PFOS/6 : 2 fluorotelomer sulfonate ≈ 2.3). The results demonstrate that sonolysis is a promising approach to treat PFASs in aqueous streams. Furthermore, they underscore that the chemical structure of PFASs has a marked effect on the rate at which they undergo sonochemical degradation

Appraising Forgeability and Surface Cracking in New Generation Cast and Wrought Superalloys

Surface cracking poses a major problem in industrial forging, but the scientific understanding of the phenomenon is hampered by the difficulty of replicating it in a laboratory setting. In this work, a novel laboratory-scale experimental method is presented to investigate forgeability in new generation cast and wrought superalloys. This new approach makes possible appraising the prevalence and severity of surface cracking by mimicking the die chilling effects characteristic of hot die forging. Two high γ′-reinforced alloys are used to explore this methodology. A Gleeble thermo-mechanical simulator is used to conduct hot compression tests following a non-isothermal cycle, with the aim to simulate the cooling of the near-surface regions during the forging process. FEA simulations, sample geometry design, and heat-treatments are used to ensure the correspondence between laboratory and real-scale forging. A wide range of surface cracking results are obtained for different forging temperatures and cooling rates—proving the soundness of the method. Surprisingly, samples heated up to higher initial temperatures typically show more extensive surface cracking. These findings indicate that—along with the local mechanical conditions of the forging—die-chilling effects and forging temperatures are paramount in controlling surface cracking, as they dictate the key variables governing the distribution and kinetics of γ′ formation

As xoias de Regodreigón.

66 (1-2) Jan.-Jun. 1956, p. 90-96

Block Copolymer Directed Metamaterials and Metasurfaces for Novel Optical Devices

Optical metamaterials are artificially engineered architectures that exhibit desired optical properties not found in nature. Bespoke design requires the ability to define shape, size, orientation, and composition of material structures on the nanometer length scale. Bottom-up self-assembly methods, such as block copolymer (BCP) templating, offer unique pathways to tailored features, at spatial resolution not routinely achieved by conventional top-down techniques. In this review, the authors provide the general readership with basic concepts of the underlying fabrication processes and examine optical phenomena arising from BCP-derived metamaterials and nanoresonators, with both dielectric and plasmonic characteristics. A number of diverse structural conformations designed by BCP templating and their implementation in optical devices is evaluated. The discussion includes 3D metamaterials, such as gyroidal and hyperbolic arrangements, as well as 2D metasurfaces. Based on recent developments in exploring these emerging structural and material configurations, the review further highlights unexplored opportunities offered by BCP self-assembly for novel metamaterials and metasurface devices

Alfabetización en salud y COVID-19 en mayores: aproximación desde la Farmacia Comunitaria

Introducción: La alfabetización en salud son las habilidades cognitivas y sociales que determinan que los individuos puedan acceder, entender y usar la información para promover y mantener su salud. La necesidad de estas habilidades ha sido notable en la pandemia.  Método: Se realiza un cuestionario específico a los pacientes mayores de 60 años. Este consta de tres partes: el instrumento HLS-EU-Q16 adaptado a COVID-19, preguntas sobre la actuación del farmacéutico y la herramienta SAHLSA. Resultados: La población era mayoritariamente femenina (75,4%) y su edad era de 79,2±9,4 años. El nivel educativo mayoritario fue de educación primaria (34,4%), predominando éste y el sin estudios en mayores de 80 años. El cuestionario HLS-EU-Q16 reveló que la alfabetización en salud sobre COVID-19 era deficiente (23%), insuficiente (70,5%) y suficiente (6,6%). El cuestionario SAHLSA mostró alfabetización suficiente en el 80%. Mientras que el primer cuestionario no mostró relación con el nivel educativo, ningún bachiller o universitario presentó valores insuficientes en el cuestionario SAHLSA. Por último, los entrevistados consideraron como primer sanitario al que acudir para obtener información fiable al médico (77%), seguido por el farmacéutico (13%). El 75% consideró que el farmacéutico le había ayudado a comprender las precauciones frente a la COVID-19.  Conclusiones: Los pacientes presentan dificultades para identificar la información fiable y para encontrar información de tratamientos frente a la COVID. Esta necesidad no está relacionada con el nivel educativo ni con la alfabetización en salud en otras áreas. El farmacéutico puede ser un agente clave en resolver esta necesidad