3,828 research outputs found

    Conductivity of Coulomb interacting massless Dirac particles in graphene: Regularization-dependent parameters and symmetry constraints

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    We compute the Coulomb correction C\mathcal{C} to the a. c. conductivity of interacting massless Dirac particles in graphene in the collisionless limit using the polarization tensor approach in a regularization independent framework. Arbitrary parameters stemming from differences between logarithmically divergent integrals are fixed on physical grounds exploiting only spatial O(2)O(2) rotational invariance of the model which amounts to transversality of the polarization tensor. Consequently C\mathcal{C} is unequivocally determined to be (19−6π)/12(19- 6\pi)/12 within this effective model. We compare our result with explicit regularizations and discuss the origin of others results for C\mathcal{C} found in the literature

    Esterilização de suco de abacaxi por microfiltração

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    bitstream/item/75839/1/ct39-2000.pd

    Redução da viscosidade da polpa de acerola.

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    bitstream/item/75825/1/ct37-2000.pd

    Exploring dynamic lighting, colour and form with smart textiles

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    This paper addresses an ongoing research, aiming at the development of smart textiles that transform the incident light that passes through them – light transmittance – to design dynamic light without acting upon the light source. A colour and shape change prototype was developed with the objective of studying textile changes in time; to explore temperature as a dynamic variable through electrical activation of the smart materials and conductive threads integrated in the textile substrate; and to analyse the relation between textile chromic and morphologic behaviour in interaction with light. Based on the experiments conducted, results have highlighted some considerations of the dynamic parameters involved in the behaviour of thermo-responsive textiles and demonstrated design possibilities to create interactive lighting scenarios.This work is supported by FEDER funds through the Operational Programme for Competitiveness Factors – COMPETE and National Funds through FCT – Foundation for Science and Technology within the scope of the projects SFRH/BD/87196/2012, POCI-01-0145-FEDER-007136 and UID/CTM/00264. The authors also like to acknowledge Smart Textiles Design Lab for the support on the prototype development.info:eu-repo/semantics/publishedVersio

    Production of grape juice powder obtained by freeze-drying after concentration by reverse osmosis.

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    This study aimed to evaluate the freeze-drying process for obtaining grape juice powder by reverse osmosis using 50% grape juice pre-concentrated (28.5 °Brix) and 50% hydrocolloids (37.5% maltodextrin and 12.5% arabic gum)
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