Marginal deterioration of the silicone for facial prosthesis with pigments after effect of storage period and chemical disinfection

The failure of facial prostheses is caused by limitations in the properties of existing materials, especially flexibility and durability. Therefore, this study evaluated the marginal deterioration of a silicone used for fabrication of facial prostheses (Silastic MDX4-4210, Dow Corning Corporation, Midland, MI, USA) according to the influence of artificial aging, daily disinfection, and 2 types of pigmentation. Thirty specimens were fabricated and subdivided in 6 groups: without pigmentation, pigmented with make-up powder and iron oxide, and evaluated with and without the action of the disinfectant. Analysis of marginal deterioration was performed on a scanning electron microscope (magnification, ×5000) immediately 6 months and 1 year after fabrication of specimens, following the guidelines of ASTM International. After visual analysis of the photomicrographs, it was noticed that all groups presented marginal deterioration and alterations in surface texture with time. The use of disinfection did not contribute to the marginal deterioration of polymer (silicone), regardless of the pigmentation and artificial aging.

Avaliação da infiltração marginal de três cimentos endodônticos após preparo para retentor de acordo com o momento do preparo

Objetivo: o objetivo desse estudo in vitro foi avaliar a infiltração marginal coronária após o preparo para retentor em dentes obturados com três diferentes cimentos, de acordo com o período entre a obturação do canal radicular e o preparo para retentor. Métodos: Noventa dentes humanos recentemente extraídos foram limpos e instrumentados e, então, obturados com Sealapex, Endométhasone ou TopSeal. Brocas Gates-Glidden foram utilizadas para o preparo imediato de 10 dentes de cada cimento até manter 5mm de obturação remanescente. Sessenta raízes obturadas foram incubadas a 37°C em meio úmido por 30 e 60 dias para serem, depois, preparadas para os retentores como descrito anteriormente. A superfície externa de cada raiz foi coberta com Araldite. Os espécimes foram imersos em corante azul de metileno a 2% sob vácuo por 24h, para então poderem ser analisados. A infiltração foi mensurada pelo software Sigma Scan da parte superior da obturação à porção apical alcançada pelo corante. Resultado: o Sealapex e o TopSeal apresentaram menor infiltração após o preparo para retentor do que o Endométhasone. O preparo imediato para o retentor apresentou menor infiltração do que o preparo para o retentor após 30 e 60 dias da obturação do canal radicular.

A escrita na formação inicial docente: o que escrevem os futuros professores?

Pós-graduação em Educação - IBRC

Análise da efetividade de polimerização, adaptação marginal e interna de restaurações Classe II de resinas compostas de inserção em bloco utilizando diferentes matrizes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Colonização bacteriana na região marginal de restaurações cerâmicas: efeito do método de remoção do cimento e do polimento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Colonização bacteriana na região marginal de restaurações cerâmicas: efeito do método de remoção do cimento e do polimento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Lindelof spaces which are indestructible, productive, or D

We discuss relationships in Lindelof spaces among the properties "indestructible". "productive", "D", and related properties. (C) 2011 Elsevier B.V. All rights reserved.

On universal Banach spaces of density continuum

We consider the question whether there exists a Banach space X of density continuum such that every Banach space of density at most continuum isomorphically embeds into X (called a universal Banach space of density c). It is well known that a""(a)/c (0) is such a space if we assume the continuum hypothesis. Some additional set-theoretic assumption is indeed needed, as we prove in the main result of this paper that it is consistent with the usual axioms of set-theory that there is no universal Banach space of density c. Thus, the problem of the existence of a universal Banach space of density c is undecidable using the usual axioms of set-theory. We also prove that it is consistent that there are universal Banach spaces of density c, but a""(a)/c (0) is not among them. This relies on the proof of the consistency of the nonexistence of an isomorphic embedding of C([0, c]) into a""(a)/c (0).

MAXIMAL PSEUDOCOMPACT AND MAXIMAL R-CLOSED SPACES

In this paper a space X is pseudocompact if it is Tychonoff and every real-valued continuous function on X is bounded. We obtain conditions under which a Tychonoff space is maximal pseudocompact and study conditions under which a regular space is maximal R-closed.

GEOMETRIC RELATIONS BETWEEN SPACES OF NUCLEAR OPERATORS AND SPACES OF COMPACT OPERATORS

We extend and provide a vector-valued version of some results of C. Samuel about the geometric relations between the spaces of nuclear operators N(E, F) and spaces of compact operators K(E, F), where E and F are Banach spaces C(K) of all continuous functions defined on the countable compact metric spaces K equipped with the supremum norm. First we continue Samuel's work by proving that N(C(K-1), C(K-2)) contains no subspace isomorphic to K(C(K-3), C(K-4)) whenever K-1, K-2, K-3 and K-4 are arbitrary infinite countable compact metric spaces. Then we show that it is relatively consistent with ZFC that the above result and the main results of Samuel can be extended to C(K-1, X), C(K-2,Y), C(K-3, X) and C(K-4, Y) spaces, where K-1, K-2, K-3 and K-4 are arbitrary infinite totally ordered compact spaces; X comprises certain Banach spaces such that X* are isomorphic to subspaces of l(1); and Y comprises arbitrary subspaces of l(p), with 1 < p < infinity. Our results cover the cases of some non-classical Banach spaces X constructed by Alspach, by Alspach and Benyamini, by Benyamini and Lindenstrauss, by Bourgain and Delbaen and also by Argyros and Haydon.

Average control of Markov decision processes with Feller transition probabilities and general action spaces

This paper studies the average control problem of discrete-time Markov Decision Processes (MDPs for short) with general state space, Feller transition probabilities, and possibly non-compact control constraint sets A(x). Two hypotheses are considered: either the cost function c is strictly unbounded or the multifunctions A(r)(x) = {a is an element of A(x) : c(x, a) <= r} are upper-semicontinuous and compact-valued for each real r. For these two cases we provide new results for the existence of a solution to the average-cost optimality equality and inequality using the vanishing discount approach. We also study the convergence of the policy iteration approach under these conditions. It should be pointed out that we do not make any assumptions regarding the convergence and the continuity of the limit function generated by the sequence of relative difference of the alpha-discounted value functions and the Poisson equations as often encountered in the literature. (C) 2012 Elsevier Inc. All rights reserved.

New characterizations for hyperbolic cylinders in anti-de Sitter spaces

In this paper we study complete maximal spacelike hypersurfaces in anti-de Sitter space H-1(n+1) with either constant scalar curvature or constant non-zero Gauss-Kronecker curvature. We characterize the hyperbolic cylinders H-m(c(1)) x Hn-m(c(2)), 1 <= m <= n - 1, as the only such hypersurfaces with (n - 1) principal curvatures with the same sign everywhere. In particular we prove that a complete maximal spacelike hypersurface in H-1(5) with negative constant Gauss-Kronecker curvature is isometric to H-1(c(1)) x H-3(c(2)). (C) 2012 Elsevier Inc. All rights reserved.

COPIES OF c(0)(Gamma) IN C(K, X) SPACES

We extend some results of Rosenthal, Cembranos, Freniche, E. Saab-P. Saab and Ryan to study the geometry of copies and complemented copies of c(0)(Gamma) in the classical Banach spaces C(K, X) in terms of the carclinality of the set Gamma, of the density and caliber of K and of the geometry of X and its dual space X*. Here are two sample consequences of our results: (1) If C([0, 1], X) contains a copy of c(0)(N-1), then X contains a copy of c(0)(N-1). (2) C(beta N, X) contains a complemented copy of c(0)(N-1) if and only if X contains a copy of c(0)(N-1). Some of our results depend on set-theoretic assumptions. For example, we prove that it is relatively consistent with ZFC that if C(K) contains a copy of c(0)(N-1) and X has dimension NI, then C(K, X) contains a complemented copy of cc(0)(N-1).

Gauge and integrable theories in loop spaces

We propose an integral formulation of the equations of motion of a large class of field theories which leads in a quite natural and direct way to the construction of conservation laws. The approach is based on generalized non-abelian Stokes theorems for p-form connections, and its appropriate mathematical language is that of loop spaces. The equations of motion are written as the equality of a hyper-volume ordered integral to a hyper-surface ordered integral on the border of that hyper-volume. The approach applies to integrable field theories in (1 + 1) dimensions, Chern-Simons theories in (2 + 1) dimensions, and non-abelian gauge theories in (2 + 1) and (3 + 1) dimensions. The results presented in this paper are relevant for the understanding of global properties of those theories. As a special byproduct we solve a long standing problem in (3 + 1)-dimensional Yang-Mills theory, namely the construction of conserved charges, valid for any solution, which are invariant under arbitrary gauge transformations. (C) 2012 Elsevier B.V. All rights reserved.