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At least 991 records · Page 55Linked to original sources
PubMed1996

Platelet deposition and fibrinogen binding on surfaces coated with heparin or friction-reducing polymers.

The blood-contacting properties of polyethylene coated with a lubricious hydrophilic coating; an uncoated polyethylene; or a photoheparin-treated polyethylene-negative control sample were compared by measuring fibrinogen adsorption, antifibrinogen binding, and platelet attachment from human plasma. The polyethylene surfaces coated with a hydrophilic polymer were found to be similar to surfaces coated with heparin. Fibrinogen adsorption on the hydrophilic coating was 60% lower than adsorption on either the uncoated or heparin-coated polyethylene samples. Antifibrinogen binding from buffer to the hydrophilic coating was also reduced more than 85% from binding to uncoated polyethylene samples. Both the hydrophilic coating and heparin coating showed a reduction in platelet attachment by a factor of 100 over the uncoated sample as well as significantly reduced platelet activation.

Acrylic Resins↗
PubMed1997

[Total hip prostheses, friction lever and wear].

The increased number of joint prostheses now being implanted into younger and active patients has made wear on polyethylene more apparent. This wear is the consequence of the bearing surface of polyethylene against metal. Research into the problem of wear is complex and other models such as metal-on-metal implants, ceramic-on-ceramic implants are tried to decrease the amount of particles accumulated after wear and avoid inflammatory reactions leading to bone lysis and implant loosening between 10 and 20 years.

Biocompatible Materials↗
PubMed1998

Measurement of soft tissue strain in response to consecutively increased compressive and distractive loads on a friction-based test bed.

PURPOSE: To abstract the essential elements of chiropractic prone leg checking and subject them to controlled, experimental parametric testing. DESIGN: Controlled, objective, repeated-measure analysis of the dynamic response of leg positions to distractive and compressive loading conditions. SETTING: Research laboratory in a chiropractic college. PARTICIPANTS: Twenty-five compression and 30 distraction subjects, most of whom were male, asymptomatic chiropractic students. INTERVENTION: The subjects were lowered to the prone position on a table optimized to detect dynamic leg positions, with separate sliding segments supporting each leg. A trial consisted of a 2-min control run, followed by two 2-min experimental runs in which compressive or distractive loads were applied incrementally to the table-leg segments. MAIN OUTCOME MEASURE: An optoelectric system measured real-time absolute and relative leg positions. RESULTS: Right legs showed a greater average response than left legs under both distractive and compressive loads, and tended to respond more proportionately to incremental load increases. The average response to compression exceeded the response to distraction. Both legs showed a greater average response in the second half of the trials. Correlation of weights with responses was about four times greater in traction than compression. CONCLUSION: The functional short leg is confirmed as a stable clinical reality, a multitrial mean of unloaded leg positional differences. The prone leg check may be a loading procedure, albeit unmeasured, that detects non-weight-bearing, functional asymmetry in loading responses. These probably reflect differences in left-right muscle tone, joint flexibility and tissue stiffness. The relatively nonmonotonic, nonlinear quality of left leg responses is consistent with asymmetric neurological responses.

Adult↗
PubMed1996

Deformation behavior of low-carbon Co-Cr-Mo alloys for low-friction implant applications.

The plastic flow behavior of wrought Co-27Cr-5Mo-0.05C alloy was investigated at 298 K as a function of grain size using uniaxial tension testing. The microstructures produced by deformation were characterized using X-ray diffraction, reflected light, and scanning electron microscopy. This study revealed that material with initially coarse face-centered cubic (fcc) grains exhibits larger uniform ductility than material with fine grain size. Typically, increasing the grain size from 7 to 70 microns reduces the yield strength by about 50% and increases the elongation to fracture from 12 to 30% with a small effect on the tensile strength. The material is capable of deforming uniformly to large strains without developing plastic instabilities until the point of fracture. This effect was found to be associated with the occurrence of transformation-induced plasticity (TRIP) in the coarse-grained material. TRIP enhances the material's ability to deform uniformly by maintaining a high rate of strain hardening during deformation. Smaller fcc initial grain size inhibits the transformation kinetics of the fcc-hexagonal close-packed phase transition according to the Olson-Cohen model.

Alloys↗