statement of problem: recent clinical results for zirconia all-ceramic restorations have revealed that the fracture rate 6-15% of the zirconia framework is so low and the core of zirconia has high stability. however, chipping-off fractures of porcelain are the most common reason for failures of zirconia in the fixed partial dentures. objectives: the purpose of this study was to compare the shea...

III Abstract: This study aims at the energy absorption problems in the crash of high speed vehicles, bird impact and crashworthiness design of aircraft, and the dynamic enhancement and multi-axial behavior of honeycombs under combined shearcompression are investigated. The study consists mainly of two parts. The first part is related to the dynamic strength enhancement of honeycombs under uniax...

The purpose of this study was to evaluate the shear bond strengths of four light-cured glass ionomer cements used for direct bonding of ceramic brackets, and to compare the results with a two-paste chemically-cured composite resin. Two commercially available polycrystalline ceramic brackets, with either chemically or mechanically retentive bracket bases, were evaluated. The brackets were bonded...

Near-fault ground motions have caused very much damage in the vicinity of seismic sources during recent earthquakes. It is well known that under specific circumstances, intensive ground shakings near fault ruptures may be characterized by short-duration impulsive motions. This pulse-type motion is generally particular to the forward direction, where the fault rupture propagates towards the site...

PURPOSE The aim of this study was to establish reference values for segmental myocardial strain measured by magnetic resonance (MR) cardiac tagging in order to characterize the regional function of the heart. MATERIAL AND METHODS We characterized the left ventricular (LV) systolic deformation in 39 subjects (26 women and 13 men, age 58.8 ± 11.6 years) whose cardiological study had not reveale...

Alkyd resins are amongst the most important and widely used resins in coating sectors. In this communication we report on preparation of alkyd resins emulsified by grafted acrylic resins on their fatty acid moieties. Both high-shear mechanical homogenizer and ultra-sonic sonicator were used step-wise to disperse the alkyd resin and acrylic based monomers in aqueous media. The resins are of nano...

In the present study, friction spot welding or refill friction stir spot welding was performed to consolidate dissimilar AA5754 Al and AZ31 Mg alloys. The intermetallic compounds of Al12Mg17 and Al3Mg2 were primarily found in the weld, distributed at the interface between the base materials and in the Al top sheet. The distribution of the intermetallic compounds and the interfacial area between...

three-dimensional surface geometry of rock discontinuities and its evolution with shearing are of great importance in understanding the deformability and hydro-mechanical behavior of rock masses. in the present research, surfaces of three natural rock fractures were digitized and studied before and after the direct shear test. the variography analysis of the surfaces indicated a strong non-line...