Fabrication of PVDF/PMMA Polymer for Sustainable Energy Harvesting

Abstract: The synthesis of blends that combine properties of two or more polymeric materials is increasingly investigated due to the versatility of the synthesis and its growing potential for many applications, including sustainability. Their characteristics are defined mainly by the synthesis conditions. Therefore, this paper details the synthesis process of easy-to-handle films using mixing method. The procedures and drawbacks found during the preparation of composite films are described. Polymeric compounds formed by the mixture of polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA) are addressed, varying the concentration, and evaluating their impact on the piezoelectric capacity. Films were formed through the spin-coating technique and characterized by optical and holographic microscopes. The results showed that composites with a concentration of 50 wt.% or larger of PVDF in the blend acquire a morphology with a granular appearance, however at lower concentrations they present a homogeneous morphology similar to that of PMMA. A homogeneous distribution of PVDF in the PMMA stands out. However, excessive contents of PMMA are associated to peaks and non-uniformities detected like multicolored regions by digital holography. Controlled strength-strain laboratory tests allowed to evaluate the film blends performance. The results indicate noticeable improvements in voltage output for a composition 70wt% PVDF and 30 wt% PMMA

Superfluorescence three-level neodymium-doped fiber source

We report on a new type of cladding-pumped neodymium-doped fiber which enables strong ASE emission at the wavelength region of 940 nm with a highly reduced emission in the four-level transition at 1060 nm when is pumped by an 806 nm source. This ASE source delivers a total emission power of 60 mW from 500 mW of absorbed pump power. The arrangement setup consisted in a pump diode emitting at 806 nm with a total output power of 1.5 W, a collimated and focused lenses and a dichroic mirror. The broadband of the neodymium source was measured to be 25 nm. Moreover, a numerical simulation for the ASE source is also discussed

Estudio multicéntrico prospectivo observacional sobre implantes PIP® colocados en 12 años

A pesar de la controversia existente con los implantes PIP® (Poly Implant Prothèse, Francia) son pocos los estudios que existen al respecto, por lo que determinamos realizar un análisis multicéntrico en nuestro entorno para conocer las características y el comportamiento clínico de los mismos. Planteamos un estudio multicéntrico, prospectivo y observacional, en el que participaron 7 cirujanos plásticos certificados que durante un periodo de 12 años habían colocado implantes PIP®. Analizamos clínicamente y con ultrasonido mamario todas las pacientes que acudieron a revisión, recogimos todos los datos y cuantificamos los hallazgos en aquellas que se intervinieron quirúrgicamente para revisión de los implantes. Entre enero del 2012 y febrero del 2013 acudieron a consulta 184 pacientes de las 1.315 que habían sido operados entre 1998 y 2010 (14%), evaluando un total de 368 implantes. Solo 39 pacientes (21,2%) presentaban sintomatología. Mediante ultrasonido mamario, 322 implantes (87,5%) fueron informados como íntegros y 46 (12,5%) rotos. Del total de pacientes revisadas, 55 (30%) no se reoperaron por no tener datos de rotura, mientras que 129 pacientes (70%) decidieron operarse. De ellos, solo 46 presentaban datos de rotura ecográfica (36%). Durante la cirugía se encontraron 213 implantes íntegros (83%) y 45 implantes rotos (17, 8%). No se encontraron datos de malignidad en las piezas de biopsia tomadas de las cápsulas o en el líquido periprotésico; tampoco crecimiento bacteriano. El índice de rotura comprobada, 17,8%, fue mayor que el que presentan otros estudios pero que tienen tiempos de seguimiento más cortos. No se encontró irritación de tejidos o sintomatología mamaria en los implantes íntegros, ni datos de toxicidad en las cápsulas o en el líquido en los implantes rotos. En base a todo ello consideramos que no es mandatorio retirar los implantes PIP® como medida de rutina, sino hacerlo cuando exista evidencia o sospecha de rotura. Creemos que el ultrasonido mamario es un estudio altamente confiable para la evaluación de la integridad de estos implantes

Molecular dynamics simulations to explore the active/inactive conformers of guinea pig β₂ adrenoceptor for the selective design of agonists or antagonists

<div><p>It is well known that guinea pig β₂ adrenoceptors (Gβ₂ARs) and human β₂ adrenoceptors (Hβ₂ARs) have structural similarity. However, only one conformational state of Gβ₂ARs has been studied – the putative inactive state. As adrenoceptors have a repertoire of conformations, and there is evidence that a certain conformation is stabilised as a ligand approaches, the aim of this study was to build four models of Gβ₂ARs by using putative active/inactive Hβ₂AR conformers as a template. We evaluated the accuracy of these models in regard to the binding mode and affinity values of a set of known β₂AR ligands through docking and molecular dynamics simulations. During docking simulations, ligands reached Gβ₂AR sites similar to those reported for Hβ₂ARs. The greatest differences between conformational states were found in the domains (TM5 and TM6) previously suggested as being key to ligand recognition. The coefficients of determination between experimental and calculated affinity values were near to but less than 0.66 in all cases. The highest values were for agonists on the active models and antagonists on the inactive model. The four Gβ₂AR models proved useful for analysing agonist/antagonist activity. The results suggest that the selection of an adequate model is dependent on the intrinsic activity of a given ligand.</p></div