Statement of problems: Two potential problems commonly identified with a denture base incorporating a resilient liner are a failure of the bond between the acrylic resin and resilient liner material and colonization of Candida albicans over time. Aims: This in vitro experimental study evaluated the shear and compressive bond strength as well as colonization of Candida albicans of commonly avail...

the purpose of this study was to compare shear bond strength (sbs) of orthodontic brackets bonded to enamel prepared by er:yag laser with two different powers and conventional acid-etching.forty-five human premolars extracted for orthodontic purposes were randomly assigned to three groups based on conditioning method: group 1- conventional etching with 37% phosphoric acid; group 2- irradiation ...

When using shear testing to determine wall friction of pharmaceutical particulate systems, it is crucial to measure at the correct wall normal stress. By comparing data obtained at a wall normal stress of 1000 to 200 Pa, the effect of the applied stress on the accuracy and precision of the method was assessed. INTRODUCTION When powder flows under gravity from a hopper, it follows one of two pat...

This study uses a torsional split-Hopkinson bar to investigate the shear response and fracture characteristics of unweldable Al-Sc alloy during mechanical testing at shear strain rates of 800 s , 1500 s , 2200 s 1 and 2800 s 1 and temperatures of 150 C, 25 C and 300 C. The experimental results show that both the shear strain rate and the temperature have a significant effect on the shear proper...

1 AAN013 shear rate behavior. For example, gauge variation can be caused by variable post-extrusion die swell, and warpage can occur from non-uniform relaxation during cooling of an improperly formulated injection molding compound. Also, by testing at low enough shear rates so that the measurements are in the melt’s linear viscoelastic region, the data can be linked directly to the polymer’s mo...

Uniaxial tensile tests were conducted on a Zr-based bulk metallic glass (BMG) with a nominal composition of Zr52.5Cu17.9Ni14.6Al10.0Ti5.0 (at.%). An infrared (IR) camera was utilized in situ during tensile testing to observe shear band evolution and fracture in the BMG. This unique visualization technique revealed that the temperature along the axis of shear band propagation constantly decrease...

Many investigators consider the polymethylmethacrylate-bone interface the weakest link in the bone-cement-implant system. Push-out tests, frequently used for in vitro evaluation of the bone-cement interface, produced inconsistent results of shear strength. Therefore, a more reliable model for testing the shear failure of the interface was developed. Better understanding of intrinsic variations ...

The non-Newtonian shear rheology of colloidal dispersions is the result of the competition and balance between hydrodynamic (dissipative) and thermodynamic (conservative) forces that lead to a nonequilibrium microstructure under flow. We present the first experimental measurements of the shear induced microstructure of a concentrated, near hard-sphere colloidal dispersion through the shear thic...

BACKGROUND The DASCOR device has recently been introduced as an innovative nucleus replacement alternative for the treatment of low-back pain caused by degenerative intervertebral disc disease. The purpose of this study was to characterize, through a series of preclinical mechanical bench and biomechanical tests, the effectiveness of this device. METHODS A number of samples were created using...

background: debonding of denture teeth from denture bases is the most common failure in removable dentures. the purpose of this study was to evaluate the effect of surface treatments on shear bond strength of denture teeth to heat-polymerized and autopolymerized denture base resins. materials and methods: in this experimental in vitro study, 60 maxillary central incisor acrylic teeth were divid...