objective: in a cavity prepared through endodontic surgery, application of a material to provide apical seal and prevent bacterial and tissue exudates is of great importance. the purpose of this study was to compare the sealing ability of biocalex with white mta, gray mta, and amalgam as root-end fillings. materials and methods: sixty-six single-rooted extracted human teeth were cleaned, shaped...

UNLABELLED Calcium oxide, available for decades as a root canal filling material, has been little used in recent years due to its lack of radio-opacity, and an expectation that it would lead to an excess of root fractures. In this study, four general dentists submitted 79 cases of endodontically treated teeth whose roots were filled with either Biocalex 6/9, or Endocal-10, and rendered adequate...

We want to understand whether and to what extent the maximal (Carnot) efficiency for heat engines can be reached at a finite power. To this end we generalize the Carnot cycle so that it is not restricted to slow processes. We show that for realistic (i.e., not purposefully designed) engine-bath interactions, the work-optimal engine performing the generalized cycle close to the maximal efficienc...

The wave equation, ∂ttu = ∆u, in R, considered with initial data u(x, 0) = f ∈ H(R) and u′(x, 0) = 0, has a solution which we denote by 1 2 (e √ −∆f + e−it √ −∆f). We give almost sharp conditions under which sup0<t<1 |e ±it √ −∆f | and supt∈R |e ±it √ −∆f | are bounded from H(R) to L(R).