statement of problem: chemo-mechanical caries removal is an effective alternative to the traditional rotary drilling method. one of the factors that can influence micro-leakage is the method of caries removal. objectives: to compare the micro-leakage of resin composite in primary dentition using self-etch and all-in one adhesives following conventional and chemo-mechanical caries removal. mater...

The effect of central opening on the buckling and nonlinear post-buckling response of carbon nanotubes (CNTs) reinforced micro composite plate embedded in elastic medium is considered in this paper. It is assumed that the system is surrounded by elastic medium, therefore; the influence of Pasternak foundation on buckling and post-buckling behavior are analyzed. In order to derive the basic form...

In this paper, the flexural free vibrations of three dimensional micro beams are investigated based on strain gradient theory. The most general form of the strain gradient theory which contains five higher-order material constants has been applied to the micro beam to take the small-scale effects into account. Having considered the Euler-Bernoulli beam model, governing equations of motion are w...

Micro scale boiling behavior in the vicinity of graphite micro-fiber tips on the coppergraphite composite boiling surfaces is investigated. It is discovered that a large number of micro bubbles are formed first at the micro scratches and cavities on the copper matrix in pool boiling. In virtue of the non-wetting property of graphite, once the growing micro bubbles touch the graphite tips, the m...

In this paper, dynamic behavior of a functionally graded cantilever micro-beam and its pull-in instability, subjected to simultaneous effects of a thermal moment and nonlinear electrostatic pressure, has been studied. It has been assumed that the top surface is made of pure metal and the bottom surface from a metal–ceramic mixture. The ceramic constituent percent of the bottom surface ranges fr...

A new method is presented to fabricate out-of-plane microstructures using traditional planar micromachining technology. Composite LPCVD polysilicon/silicon nitride beams are fabricated to study this concept. Polysilicon films ranging from 0.5 μm to 1.3 μm, and silicon nitride films ranging from 150 to 450 nm, were used to fabricate various thickness ratios of composite out-of-plane microstructu...

We report the first fabrication of vertical three-dimensional micro-Fresnel lenses with polysilicon materials by surface micromachining technique. Micro-Fresnel lenses play a very important role in micro-optics because of their thin film structures and their ability to achieve very short focal lengths. Although micro-Fresnel lenses have been studied and well understood [ 11, the lens planes usu...

micro-leakage, one of the major reasons for recurrent decays, may lead to uncontrollable flow of liquids, pulp inflammation and peri-apical pathology. the purpose of this in vitro study was to evaluate micro-leakage of pit and fissure sealants after using three different pit and fissure preparation techniques: 1) acid etching, 2) fissure enameloplasty and acid etching, and 3) air abrasion and a...

background and aim: in vitro studies have revealed a direct association between resin content and cytotoxicity of resin composites; but implantation studies in this regard are sparse. this study investigates the relationship between filler content of composite resins and biocompatibility. materials and methods: this study was conducted using 18 male wistar rats (180-200g), 1 nano-hybrid (prime-...

In this paper, the effect of the crack on dynamic behavior of cracked micro-beam in the presence of DC and AC loads are investigated. By applying the residual axial stress and fringing field stress, a nonlinear analytical model of cracked micro-beam is presented and crack is modeled by a massless rotational spring. The governing equation of the system is solved using Galerkin procedure and shoo...