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Biomedical subjects

J C Bokros

Publications and source records attributed to J C Bokros.

7 recordsLinked to original sources
PubMed1998

Pure pyrolytic carbon: preparation and properties of a new material, On-X carbon for mechanical heart valve prostheses.

BACKGROUND AND AIM OF THE STUDY: Historically, the pyrolytic carbon used in mechanical prosthetic heart valves contained small amounts of silicon, this being a necessary additive to achieve consistently the hardness required for wear resistance. New processing technology has allowed the deposition of pyrolytic carbon without silicon, while maintaining adequate hardness to ensure wear resistance. METHODS: A parametric study of coating parameters identified the conditions necessary to produce the optimal pure carbon material. RESULTS: In comparison with silicon-alloyed carbon, the pure carbon was found to be about 20% stronger, have a strain-to-failure about 25% higher and have a greater toughness. CONCLUSIONS: The enhanced strength, deformability and toughness of the new carbon permits designers to utilize component shapes and dimensions that could not be manufactured using the silicon-alloyed carbons. Such design features have hemodynamic benefits resulting in valve performance improvements.

Carbon↗
PubMed1979

Developments in carbon prosthetics.

The majority of carbon-coated prosthetic devices in use today are coated with a unique form of carbon, low-temperature isotropic (LTI) carbon. The wide acceptance of this special form of carbon is a direct result of LTI carbon's demonstrated biocompatibility, its mechanical properties, and its inertness. The LTI carbon deposition process, however, places severe constraints on the size and type of substrate that can be coated. The substrates must be small so that they may be supported in a fluidized bed and further must be able to withstand temperatures in excess of 1200 degrees C. Recent technological advancements have removed the requirement that an object to be coated must be suspended in a fluidized bed and have also made possible the deposition of isotropic carbon at near room temperature. These developments expand the application of carbon-surfaced components into areas of prosthetics not previously possible. This paper describes some of the new applications and results.

Animals↗