2,258 research outputs found

    Recycling of composite materials. Application to the car industry

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    En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.-- 3 pages, 1 figure.A pressing problem, in developed countries is the recycling of vehicles, particularly cars and trucks. In general, there are three types of vehicles for recycling: 1. The old models, not designed for recycling. They are metallic mostly. Different components, fed up recycling metal and other materials recycling, is scheduled separated in a way If the vehicle is already planning for a smart recycling there are two choices: 2. Vehicles designed for recycling with metallic body 3. Recyclable vehicles finally containing high percentage of non-metallic materials, as composites. The problematic in recycling of is included in this contribution, in special new process for composite recycling.Peer reviewe

    Black hole shadow of a rotating polytropic black hole by the Newman--Janis algorithm without complexification

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    In this work, starting from a spherically symmetric polytropic black hole, a rotating solution is obtained by following the Newman--Janis algorithm without complexification. Besides studying the horizon, the static conditions and causality issues of the rotating solution, we obtain and discuss the shape of its shadow. Some other physical features as the Hawking temperature and emission rate of the rotating polytropic black hole solution are also discussed.Comment: 9 pages, 2 figures, some references adde

    Ionic behavior assessment of surface-active compounds from corn steep liquor by exchange resins

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    Depending on their ionic nature, biosurfactants can be classified as nonionic, anionic, cationic, or amphoteric. The ionic behavior of biosurfactants is an important characteristic that dictates their use in industrial applications. In this work, a biosurfactant extract obtained from corn steep liquor was subjected to anionic or cationic resins, in order to study the ionic behavior under different operational conditions using response surface methodology. The independent variables included in the study are the dilution of biosurfactant solution, the amount of cationic or anionic resin, and the extraction time, whereas the dependent variables studied consisted of the surface tension of biosurfactant aqueous solution, after contacting with anionic or cationic resin. The results showed that biosurfactant extracted from corn steep liquor is amphoteric, since both resins were able to entrap this biosurfactant, making it particularly suited for use in personal care preparations for sensitive skin.Peer ReviewedPostprint (author's final draft

    Thermochromism of Model Organic Aerosol Matter

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    Laboratory experiments show that the optical absorptivity of model organic matter is not an intrinsic property, but a strong function of relative humidity, temperature, and insolation. Suites of representative polyfunctional C_(x)H_(y)O_(z) oligomers in water develop intense visible absorptions upon addition of inert electrolytes. The resulting mixtures reach mass absorption cross sections σ(532 nm) ~ 0.1 m^(2)/gC in a few hours, absorb up to 9 times more solar radiation than the starting material, can be half-bleached by noon sunlight in ~ 1 h, and can be repeatedly recycled without carbon loss. Visible absorptions red-shift and evolve increasingly faster in subsequent thermal aging cycles. Thermochromism and its strong direct dependences on ionic strength and temperature are ascribed to the dehydration of >CH−C(OH)C═C< unsaturations by a polar E1 mechanism, and bleaching to photoinduced retrohydration. These transformations are deemed to underlie the daily cycles of aerosol absorption observed in the field, and may introduce a key feedback in the earth’s radiative balance

    Improved Average Complexity for Comparison-Based Sorting

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    This paper studies the average complexity on the number of comparisons for sorting algorithms. Its information-theoretic lower bound is nlgn1.4427n+O(logn)n \lg n - 1.4427n + O(\log n). For many efficient algorithms, the first nlgnn\lg n term is easy to achieve and our focus is on the (negative) constant factor of the linear term. The current best value is 1.3999-1.3999 for the MergeInsertion sort. Our new value is 1.4106-1.4106, narrowing the gap by some 25%25\%. An important building block of our algorithm is "two-element insertion," which inserts two numbers AA and BB, A<BA<B, into a sorted sequence TT. This insertion algorithm is still sufficiently simple for rigorous mathematical analysis and works well for a certain range of the length of TT for which the simple binary insertion does not, thus allowing us to take a complementary approach with the binary insertion.Comment: 21 pages, 2 figure

    Insights into the complexity of craniofacial development from a cellular perspective

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    The head represents the most complex part of the body and a distinctive feature of the vertebrate body plan. This intricate structure is assembled during embryonic development in the four-dimensional process of morphogenesis. The head integrates components of the central and peripheral nervous system, sensory organs, muscles, joints, glands, and other specialized tissues in the framework of a complexly shaped skull. The anterior part of the head is referred to as the face, and a broad spectrum of facial shapes across vertebrate species enables different feeding strategies, communication styles, and diverse specialized functions. The face formation starts early during embryonic development and is an enormously complex, multi-step process regulated on a genomic, molecular, and cellular level. In this review, we will discuss recent discoveries that revealed new aspects of facial morphogenesis from the time of the neural crest cell emergence till the formation of the chondrocranium, the primary design of the individual facial shape. We will focus on molecular mechanisms of cell fate specification, the role of individual and collective cell migration, the importance of dynamic and continuous cellular interactions, responses of cells and tissues to generated physical forces, and their morphogenetic outcomes. In the end, we will examine the spatiotemporal activity of signaling centers tightly regulating the release of signals inducing the formation of craniofacial skeletal elements. The existence of these centers and their regulation by enhancers represent one of the core morphogenetic mechanisms and might lay the foundations for intra- and inter-species facial variability

    L'Ensenyament de l'arqueologia a la Universitat

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