4,996 research outputs found

    Diffusion-limited deposition with dipolar interactions: fractal dimension and multifractal structure

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    Computer simulations are used to generate two-dimensional diffusion-limited deposits of dipoles. The structure of these deposits is analyzed by measuring some global quantities: the density of the deposit and the lateral correlation function at a given height, the mean height of the upper surface for a given number of deposited particles and the interfacial width at a given height. Evidences are given that the fractal dimension of the deposits remains constant as the deposition proceeds, independently of the dipolar strength. These same deposits are used to obtain the growth probability measure through Monte Carlo techniques. It is found that the distribution of growth probabilities obeys multifractal scaling, i.e. it can be analyzed in terms of its f(α)f(\alpha) multifractal spectrum. For low dipolar strengths, the f(α)f(\alpha) spectrum is similar to that of diffusion-limited aggregation. Our results suggest that for increasing dipolar strength both the minimal local growth exponent αmin\alpha_{min} and the information dimension D1D_1 decrease, while the fractal dimension remains the same.Comment: 10 pages, 7 figure

    Diffusion-limited deposition of dipolar particles

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    Deposits of dipolar particles are investigated by means of extensive Monte Carlo simulations. We found that the effect of the interactions is described by an initial, non-universal, scaling regime characterized by orientationally ordered deposits. In the dipolar regime, the order and geometry of the clusters depend on the strength of the interactions and the magnetic properties are tunable by controlling the growth conditions. At later stages, the growth is dominated by thermal effects and the diffusion-limited universal regime obtains, at finite temperatures. At low temperatures the crossover size increases exponentially as T decreases and at T=0 only the dipolar regime is observed.Comment: 5 pages, 4 figure

    Energy Efficiency Measures for an Electrical Material Industry

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    The main goal of the present paper is to present the study of energy efficiency measures for an electrical material industry. The high-energy consumption of this kind of industry lead companies to search for solutions that allow increasing the energy efficiency in their installations and in the processes, promoting the reduction of the energy consumption and costs. In this context, the objectives of this study emerged, which resulted from the main needs identified by the company. Therefore, the work was divided into four parts. The first one, was the study of replacing the existing lighting (mainly mercury vapor lamps by led); another study conducted was the replacement of the electric motors in injection machines by new and more efficient ones; the third one was the installation of a photovoltaic solar system (for self-consumption) and, finally, the project of a new power converter station for the company. The energy efficiency studies carried out are based on: a careful analysis of the data provided by the company; all the measurements done; the consumption profiles that have been drawn; an extensive market research (with the purpose of finding the most efficient solutions for each case); and in already existing and proven calculation methodologies, leading, in this way, to a greater reliability of the obtained results. These studies showed to which extent the implementation of the various measures presented are economically viable, their impact on the reduction of energy consumption and the annual savings achieved.This work was supported by Coimbra Institute of Engineering – Polytechnic Institute of Coimbra and by projects: UID/MULTI/00308/2019 (supported by the Portuguese ‘Fundação para a Ciência e a Tecnologia’: FCT – Foundation for Science and Technology) and by the European Regional Development Fund through the COMPETE 2020 Programme, FCT Portuguese Foundation for Science and Technology within project T4ENERTEC (POCI-01- 0145-FEDER-029820)

    Tunneling effects on impurity spectral function in coupled asymmetric quantum wires

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    The impurity spectral function is studied in coupled double quantum wires at finite temperatures. Simple anisotropy in the confinement direction of the wires leads to finite non-diagonal elements of the impurity spectral function matrix. These non-diagonal elements are responsible for tunneling effects and result in pronounced extra peak in the impurity spectral function up to temperatures as high as 20 K.Comment: Accepted in Phys. Rev.

    Synthesis of an antibody-like material for the detection of Albumin

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    6th Graduate Student Symposium on Molecular Imprinting6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, 27-28 de Agosto 2015A novel molecularly imprinted polymer (MIP) is presented for the detection of Albumin, currently a biomarker of several diseases. The material acted as an antibody for Albumin and was obtained through a bulk imprinting approach, by electropolymerizing Eriochrome blackT (EBT) around the target protein

    A novel printed 3-electrode system for the electrochemical detection of sulfadiazine

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    We thank the financial support of 3C´s – Cellulose and Cork in the Control of antibiotics in aquaculture (PTDC/AAG-TEC/5400/2014 and POCI-01-0145-FEDER-016637), to FEDER, through COMPETE2020, POCI, and FCT (Fundação para a Ciência e a Tecnologia I.P.).info:eu-repo/semantics/publishedVersio
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