The effect of radiopacifiers agents on pH,calcium release,radiopacity, and antimicrobial properties of different calcium hydroxide dressings

The aim of this study was to evaluate the antimicrobial activity, pH level, calcium ion release, and radiopacity of calcium hydroxide pastes associated with three radiopacifying agents (iodoform, zinc oxide, and barium sulfate). For the pH and calcium release tests, 45 acrylic teeth were utilized and immersed in ultrapure water. After 24 h, 72 h, and 7 days the solution was analyzed by using a pH meter and an atomic absorption spectrophotometer. Polyethylene tubes filled with the pastes were used to perform the radiopacity test. For the antimicrobial test, 25 dentin specimens were infected intraorally in order to induce the biofilm colonization and treated with the pastes for 7 days. The Live/Dead technique and a confocal microscope were used to obtain the ratio of live cells. Parametric and nonparametric statistical tests were performed to show differences among the groups (P < 0.05). The pH analysis at 7 days showed significant differences (P < 0.05) among the groups. No differences among the pastes were found in the calcium release test on the 7th day (P > 0.05). The calcium hydroxide/iodoform samples had the highest radiopacity and antimicrobial activity against the biofilm‐infected dentin in comparison to the other pastes (P < 0.05). Calcium hydroxide mixed with 17% iodoform and 35% propylene glycol into a paste had the highest pH, calcium ion release, radiopacity, and the greatest antimicrobial action versus similar samples mixed with BaSO4 or ZnO. Microsc. Res. Tech. 78:620–625, 2015. © 2015 Wiley Periodicals, Inc.     

Hydrolysis of intralipid by pancreatic lipase and phospholipase A2-gel filtration studies

Intralipid was incubated with pancreatic lipase (EC 3.1.1.3) and/or phospholipase A₂ (EC 3.1.1.4) at two bile salts/phosphatidylcholine molar ratios and at two different triglyceride hydrolysis rates using various amounts of lipase. Incubations were studied by gel filtration. Results show: (i) During lipase action, three phases of lipids coexist: an emulsified phase, a micellar phase and an intermediate heavy phase sized between the two others. The equilibrium between each phase is dependent upon the bile salts concentration. (ii) Under these conditions, pancreatic lipase was at 60% bound to the emulsified phase, whereas pancreatic phospholipase A₂ was bound at 94% to the micellar phase.     

Calibration of the EDELWEISS cryogenic heat-and-ionization germanium detectors for dark matter search

Several aspects of the analysis of the data obtained with the cryogenic heat-and-ionization Ge detectors used by the EDELWEISS dark matter search experiment are presented. Their calibration, the determination of their energy threshold, fiducial volume and nuclear recoil acceptance are detailed.     

Characterization of a coating layer on glass fibre used as reinforcing material in a polyepoxide matrix by means of FTIR spectroscopy and vapour phase interaction studies with monofunctional model compounds

Coatings on glass fibres, used to reinforce polyepoxide matrices, were examined by Fourier transform infra-red spectroscopy and by their reaction with styrene oxide, aniline, and also water in the vapour phase which was followed calorimetrically and gravimetrically. The coatings comprised an adhesive (of the DGEBA epoxy prepolymer type) applied on its own or together with a coupling agent (γ aminopropyltriethoxysilane). In all tests, these fibres were compared with untreated fibres of a similar type. The results of the studies indicate that the combination of the two coatings forms a reactive mixture within themselves which may inhibit uniform coating of the glass. It is also shown that the coating products on the glass control the process of water diffusion.     

Search directions for interior linear-programming methods

Since Karmarkar published his algorithm for linear programming, several different interior directions have been proposed and much effort was spent on the problem transformations needed to apply these new techniques. This paper examines several search directions in a common framework that does not need any problem transformation. These directions prove to be combinations of two problem-dependent vectors, and can all be improved by a bidirectional search procedure. We conclude that there are essentially two polynomial algorithms: Karmarkar's method and the algorithm that follows a central trajectory, and they differ only in a choice of parameters (respectively lower bound and penalty multiplier).     

Finite element simulation of complex interfacial segregation phenomena in dilute alloys

Segregation of trace elements on a surface, at grain boundaries or more generally in any interface can have important consequences: adhesion of thin films, catalytic activity, embrittlement of steels by P or of nickel alloys by S, reinforcement of nickel alloys by B, etc. Segregation kinetics can be simulated by a finite element (FE) approach, by implementing the Darken–Du Plessis equation at the interface and Fick’s diffusion laws in the bulk. It is then possible to simulate segregation kinetics in non-isothermal conditions, and to couple segregation and macroscopic heat transfer calculations. A previously developed model is here adapted to the case of complex interfacial segregation phenomena: (i) segregation of a single species with a solute–solute or solute–solvent interaction, (ii) co-segregation of two species with a site competition in the interface, and (iii) segregation of a single species at an interface between two phases. Results are compared with available experimental data.     

hp‐Clouds in Mindlin's thick plate model

In the last few years a number of numerical procedures called as meshless methods have been proposed. Among them, we can mention the diffuse element method, smooth particle hydrodynamics, element free Galerkin method, reproducing kernel particle method, wavelet Galerkin methods, and the so‐called hp‐cloud method. The main feature of these methods is the construction of a collection of open sets covering the domain which are used as support of the classical Galerkin approximation functions. The hp‐cloud method is focused here because of its advantage of considering from the beginning the h and p enrichment of the approximation space. In this work we present, to our knowledge, the first results concerning the behaviour of this technique on the solution of Mindlin's moderately thick plate model. It is demonstrated numerically that the behaviour of the method with respect to shear locking is essentially the same as in the p‐version of the finite element method, namely, the shear locking can be controlled by using hp cloud approximations of sufficiently high polynomial degree. The computational implementation of the method and the issue of numerical integration of the stiffness matrix are also discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Robust B-spline Snakes For Ultrasound Image Segmentation

Snake-based methods are commonly used to segment ultrasound images. However, their performance is generally limited because of the specific properties of this kind of images. This paper addresses the sensitivity of parametric active contours to speckle within ultrasound images. We propose a new B-spline snake model, founded on two original external energies specifically tailored for the segmentation of biomedical speckled images. First, the curve is attracted from a wide capture range with an expansion energy that facilitates the snake initialization. Then, it is accurately fitted on the region boundaries with an energy that allows precise positioning of the curve along edges in ultrasound images. A mutual inhibition function is designed to control the two energies. Results on real ultrasound images are presented and quantitatively compared to the boundaries manually outlined by experts. Our method improves the precision of heart cavities segmentation.     

Finite element simulation of interfacial segregation in dilute alloys

The finite element software Comsol is used to simulate surface or grain boundary segregation in dilute alloys. The model computes simultaneously the evolution of interfacial concentration and diffusion in the bulk. The solute exchange between bulk and interface is governed by Darken’s equation. The model is able to reproduce thermodynamic and kinetic aspects of the phenomenon, in particular the saturation segregation level and the short-time segregation kinetics expressed by the McLean approximation. It is also able to reproduce experimental trends in the case of surface segregation of sulphur in a Ni superalloy. In the case of the grain boundary segregation of impurities (P or S) in engineering alloys, the present approach provides a practical tool, as it can be coupled to other finite element simulations (heat transfer and/or mechanics). Thus, it becomes possible to predict the risk of synergetic segregation and thermomechanical damage during service or processing (forging, welding,...).