Experimental Investigation of Engine Valve Train Friction Considering Effects of Operating Conditions and WPC Surface Treatment.

Reduction in friction ensures fuel economy, control on emissions and durability of components in internal combustion engines. A modern gasoline internal combustion engine was instrumented to determine the friction values at the cam-roller interface considering the effects of surface treatment and engine operating state. A series of tests under different operating speeds and lubricant inlet temperatures were undertaken using both an original surface roller and a Wonder Process Craft (WPC) surface-treated engine roller. The results clearly revealed a substantial reduction in friction magnitude for the WPC surface-treated engine roller in comparison to the original roller while operating under similar conditions, indicating their strong potential for employment in engines. An increase in friction with the rise in temperature was also observed for both types of rollers, whereas increased lubricant entraining velocity due to higher operating speed had the opposite impact. A considerable reduction in frictional drive torque ranging from 8% to 28% was observed by employing the WPC-treated roller in comparison to original/untreated roller at various operating conditions, which signifies the strong potential for employment of WPC surface treatment in the roller/follower valve train engines.

Application of alpha-tricalcium phosphate coatings on titanium subperiosteal orthodontic implants reduces the time for absolute anchorage: a study using rabbit femora.

We are currently developing a small perforated titanium subperiosteal implant specifically for orthodontic therapy, which can be placed anywhere on the bone surface. In the present study, we coated this implant with hydroxyapatite (HA) or alpha-tricalcium phosphate (alpha-TCP) in an attempt to shorten the initial stabilization period relative to the few months that is usually required. The coated implants were placed beneath the periosteum in rabbit femora. The implants were observed by radiographically and histologically, and measured the tensile strength of the bone-implant interface. Two weeks after placement, the volume of new bone formed in the perforations of the implant was significantly greater for the alpha-TCP-coated implants than for the HA-coated implants. Our findings indicate that new bone is formed faster in the surrounding area with alpha-TCP- and HA-coated subperiosteal implants than with uncoated implants, and that alpha-TCP is a particularly effective stimulator of new bone formation.

The use of bioabsorbable implants as orthodontic anchorage in dogs.

The purpose of this study was to investigate the possibility of using a bioabsorbable implant as orthodontic anchorage. The implant under investigation in this study was a miniscrew, 2.0 mm x 8.0 mm, made from poly-L-lactic acid (PLLA; molecular weight: 200,000), a bioabsorbable bone-bonding material. The implants were placed in the mandibles of eight male beagle dogs. After implantation, traction was immediately applied to the third premolar (P3) using the implant as anchorage. After the completion of each study period (three and six months) following installation, tensile test, histological examination, and molecular weight measurement were performed. The results suggested that the bioabsorbable implant evaluated had favorable biocompatibility and strength, and that it showed promising potential for use in orthodontic treatment.