Cellulosic aerogels for energy applications

International audienceComing from soft chemistry (e.g. sol-gel), chemical nature and nanostructuration of aerogels can be softly tailored. Moreover, they can be lightweight and they can present very high specific area (larger than 1000 m²/g) with narrow (or even broad) pore size distribution. Such structural characteristics make them potentially interesting for various applications. A large majority of the studies dedicated to aerogels are dealing with inorganics (SiO2, TiO2, ZrO2...). Anyway, some class of organic aerogels are known to present high interest. Such materials are particularly considered as organic precursors for new nanostructured carbons. Most of the corresponding samples are coming from Resorcinol-Formaldehyde (RF) systems. During the past decade, further studies on organic aerogels for thermal insulation have addressed other kinds of aerogels, mainly based on polyurethane , and very recently polydicyclopentadiene systems. Within these sphere, except original works of Kistler, only very few works concern use of natural products. Knowing that cellulose is one of the most abundant natural materials, one can guess that combining sol-gel science and cellulose could be of high interest. Some works on elaboration of porous cellulose via drying of physical cellulose-based gels can be found but they are dealing with macroporous foams not really aerogels. , Some years ago, one of the first aerogel attempt with cellulose derivatives has been published. On this basis, we have developed a softer route (i.e. using a non toxic isocyanate). We have then examined the pyrolysis impact on the resulting carbonaceous green materials and evaluated its use as catalyst support for PEM fuel cell electrodes. Here is presented a very brief overview of the related studies we have performed since then

Protein Folding and Aggregation into Amyloid: The Interference by Natural Phenolic Compounds

Amyloid aggregation is a hallmark of several degenerative diseases affecting the brain or peripheral tissues, whose intermediates (oligomers, protofibrils) and final mature fibrils display different toxicity. Consequently, compounds counteracting amyloid aggregation have been investigated for their ability (i) to stabilize toxic amyloid precursors; (ii) to prevent the growth of toxic oligomers or speed that of fibrils; (iii) to inhibit fibril growth and deposition; (iv) to disassemble preformed fibrils; and (v) to favor amyloid clearance. Natural phenols, a wide panel of plant molecules, are one of the most actively investigated categories of potential amyloid inhibitors. They are considered responsible for the beneficial effects of several traditional diets being present in green tea, extra virgin olive oil, red wine, spices, berries and aromatic herbs. Accordingly, it has been proposed that some natural phenols could be exploited to prevent and to treat amyloid diseases, and recent studies have provided significant information on their ability to inhibit peptide/protein aggregation in various ways and to stimulate cell defenses, leading to identify shared or specific mechanisms. In the first part of this review, we will overview the significance and mechanisms of amyloid aggregation and aggregate toxicity; then, we will summarize the recent achievements on protection against amyloid diseases by many natural phenols

Aerogel-based thermal superinsulation: an overview

This review is focused on describing the intimate link which exists between aerogels and thermal superinsulation. For long, this applied field has been considered as the most promising potential market for these nanomaterials. Today, there are several indicators suggesting that this old vision is likely to become reality in the near future. Based on recent developments in the field, we are confident that aerogels still offer the greatest potential for non-evacuated superinsulation systems and consequently must be considered as an amazing opportunity for sustainable development. The practical realization of such products however is time-consuming and a significant amount of R&D activities are still necessary to yield improved aerogel-based insulation products for mass market

Effective Thermal conductivity of divided silica xerogel beds

International audienceApparent thermal conductivity (λ) measurements were made on monolithic silica aerogels and divided low-density xerogels. The objective of the tests on monoliths was to determine the variation of λ with the solid content. Additional compressive tests were also made to follow the evolution of bulk modulus with apparent density, in order to further optimize the solid content of xerogel particles. Divided xerogels were characterized under the following conditions: at ambient conditions (T, P, and relative humidity of water vapor in air), under partial vacuum (from atmospheric pressure to 4 × 10−7 bar) and under different relative humidities. The effect of the divided xerogel granularity on λ has been studied by using different size range and distributions. The results of our studies indicate an optimum particle density at 0.15 g cm−3, and a decrease in λ for samples containing fine particles

Low M r Phosphotyrosine Protein Phosphatase Associates and Dephosphorylates p125 Focal Adhesion Kinase, Interfering with Cell Motility and Spreading

Low M(r) phosphotyrosine protein phosphatase interferes in vivo with the activation of several growth factor receptors and is transiently redistributed, following cell stimulation with platelet-derived growth factor, from the cytosol to the cytoskeleton. We demonstrate here that this phosphatase also participates in the regulation of cell spreading and migration, pointing to its involvement in cytoskeleton organization. Low M(r) phosphotyrosine protein phosphatase-overexpressing fibroblasts are, indeed, less spread than controls and display a significantly decreased number of focal adhesions and increased cell motility. Furthermore, p125 focal adhesion kinase is associated to, and dephosphorylated by, low M(r) phosphotyrosine protein phosphatase both in vitro and in vivo. This event is consistent with an altered association of pp60(src) with focal adhesion kinase. The activation of extracellular signal-regulated kinase, another well known event downstream of the focal adhesion kinase, is also affected. On the other hand, cells overexpressing the dominant-negative form of low M(r) phosphotyrosine protein phosphatase exhibit hyperphosphorylated focal adhesion kinase, reduced motility, and an increased number of focal adhesions, which are distributed all over the ventral cell surface. Taken together, the results reported here are in keeping with low M(r) phosphotyrosine protein phosphatase participation in FAK-mediated focal adhesion remodeling

02731-2015-0-1801-JR-CI-15 / 00020-2015-PI/TC

El expediente en cuestión versa sobre un proceso de desalojo por ocupación precaria del inmueble ubicado en el distrito de San Borja, cuya controversia se suscita a partir del otorgamiento del título de propiedad a favor de la empresa Inversiones Warriors S.A.C., sin conocimiento de que el mismo se encontraba siendo ocupado por la Sra. E. Y. N. A. V. El demandante argumenta que adquirió el inmueble a través de contrato de compraventa suscrito con su anterior propietario, mientras que la demandada, pese a no contar con ningún tipo de vínculo o título que sustente su ocupación, se niega a desalojar el inmueble. Por su lado, la demandada alega que esta compraventa devendría en nula debido a que ella, al ser la esposa del anterior propietario, no autorizó ni fue comunicada en ningún momento sobre la suscripción del susodicho contrato. En el presente proceso se pondrá en debate la legitimidad de la posesión del inmueble por parte de la demandada en base a lo establecido en el Cuarto Pleno Casatorio Civil. En tal sentido, se tratarán los criterios establecidos para la configuración de la posesión precaria, las reglas vinculantes para la resolución de estos casos, y las formas con las cuales se puede acreditar la carencia o no de un título válido para la posesión.The file in question concerns an eviction process due to precarious occupation of the property located in the district of San Borja. The dispute arises from the granting of the property title to Inversiones Warriors S.A.C., without knowledge that it was already occupied by Mrs. E. Y. N. A. V. The plaintiff argues that they acquired the property through a sales contract signed with the previous owner, while the defendant, despite lacking any kind of legal connection or title to support their occupation, refuses to vacate the premises. On the other hand, the defendant claims that this sales contract would be void since she, being the spouse of the previous owner, did not authorize or receive any communication regarding the aforementioned contract. In the present proceedings, the legitimacy of the defendant's possession of the property will be debated based on the provisions established in the Fourth Plenary Session on Civil Law. In this regard, the criteria for establishing precarious occupation, the binding rules for resolving such cases, and the methods for proving the absence or validity of a title for possession will be addressed.Trabajo de suficiencia profesiona

Low Mr phosphotyrosine protein phosphatase activity on fibroblast growth factor receptor is not associated with enzyme translocation

AbstractFibroblast growth factor receptor (class IV) shares a certain degree of similarity with class III members like platelet-derived growth factor and macrophage-colony-stimulating factor receptors, which, once activated, are substrates of low Mr phosphotyrosine protein phosphatase. Up until now no phosphotyrosine phosphatase has been shown to act on this receptor in vivo. Here we demonstrate that low Mr phosphotyrosine protein phosphatase is able to reduce receptor tyrosine phosphorylation and cell proliferation in response to basic fibroblast growth factor. Contrary to what was previously observed for platelet-derived growth factor, during cell stimulation with basic fibroblast growth factor, no enzyme redistribution among cellular compartments is observed

Complejo deportivo con equipamiento comunitario para la promoción cultural - educativa en los jóvenes del distrito de Ventanilla, Callao 2021

La presente tesis parte de que el Complejo Deportivo con Equipamiento Comunitario es un equipamiento urbano que tiene como finalidad albergar y recibir a la juventud del distrito de Ventanilla para entrenamientos como realizar actividades recreativas pasivas y activas, así como también actividades culturales educativas. El objetivo de esta investigación es evidenciar que, a través del deporte, recreación y cultura-educacional, se puede mejorar la calidad y el estilo de vida de los jóvenes, originando una huella positiva en el aspecto físico y mental. Para ello se ha trabajado con una población de 372,899 personas y una muestra de 339 personas en su totalidad, utilizando la encuesta como instrumento de validación. Como conclusión se ha obtenido que los niños, adolescentes y jóvenes deportistas del distrito de Ventanilla tienen un estilo de vida no óptima, ya que en el distrito no existe una adecuada infraestructura y espacios destinados al deporte y recreació