A physical deduction of the FN = kh 3/2 relation (where FN is normal force, k penetration resistance and h penetration depth) for conical/pyramidal indentation loading curves has been achieved on the basis of elementary mathematics. The indentation process couples the productions of volume and pressure to the displaced material that often partly plasticizes due to such pressure. As the pressure...

AIM The aim of this study was to determine the pressure where oral soft tissue resistance will be overcome resulting in soft tissue emphysema and to measure the safety of an antifouling device for a videoscope used during minimally invasive periodontal surgery. MATERIALS AND METHODS Resistance was measured in vitro in porcine tissue. One study arm measured palatal tissue resistance to air app...

Infection structures of phytopathogenic fungi are modified hyphae specialized for the invasion of plant tissues. Initial events are adhesion to the cuticle and directed growth of the germ tube on the plant surface. At the site of penetration, appressoria are often formed that may have melanized walls and develop high turgor pressure to support the penetration process. The penetration hypha accu...

An experimental study has been conducted on the penetration of silicone rubbers and human skin in vivo by sharp-tipped and flat-bottomed cylindrical punches. A penetrometer was developed to measure the penetration of human skin in vivo, while a conventional screw-driven testing machine was used to penetrate the silicone rubbers. The experiments reveal that the penetration mechanism of a soft so...

The effects of needle bevel orientation and cerebrospinal fluid (CSF) pressure on dural displacement and force required to penetrate cadaveric dura were studied using 40 samples. A constant hydrostatic pressure was applied to the subdural surface, either high or low, simulating the sitting and lateral positions. A 17-gauge Tuohy needle was advanced through the dura with the bevel oriented paral...

Topical administration of 1% vanadate in a formulation designed to enhance penetration lowered intraocular pressure in monkeys' eyes. The decrease in intraocular pressure was associated with significant decreases in aqueous humor flow. Tonographic outflow facility was unaltered by topical vanadate.

his study was done to assess performance of four Class 95 respirator filters exposed to diesel engine exhaust. NIOSH-certified electret filters from two manufacturers were used. N95 filters from each manufacturer were tested. P95 and R95 filters from Manufacturer X and Y, respectively, were also tested. Only R and P series filters are typically recommended for diesel exposures. Prior to diesel ...