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Due to their excellent mechanical properties, Yttria-stabilized Tetragonal Zirconia Polycrystal ceramics (Y-TZP) are used in ball heads for Total Hip Replacements. It is known that Y-TZP materials may show strength degradation due to ageing or to hydrothermal treatment. Also high wear of UHMWPE sockets coupled to steam sterilized Y-TZP ball heads after a(More)
It is desired to make a preliminary report of certain experimental evidence that respiratory and other gases may enter one lobule from another in the lung without resort to known anatomical passageways. This was found in vivo and in vitro in work with dogs. In vitro observations. A single lung lobe, freshly secured, was prepared by dissection at the hilus(More)
Y-TZP ball heads were introduced into the market in 1985. Since then these components have had wide diffusion in hip replacements, due to their good mechanical performance and reliability. Namely, only a few papers were published up to year 2000 reporting failures of Y-TZP ball heads. The worldwide recall in August 2001 of some Y-TZP batches changed this(More)
There is interest in using zirconia for biomedical applications as ball heads for total hip prostheses. Two potential types are under discussion: partially stabilized zirconia (PSZ) and tetragonal zirconia polycrystals (TZP) materials. Because of its enhanced material properties, TZP stabilized with yttria is favourable. To eliminate high amounts of natural(More)
Introduction It is believed that the sympathetic nervous system through its peripheral distribution, and possibly through central connections, exerts, at least' in part, a control on vasomotor tonus. In recent years, several series of experiments on dogs have been conducted in this laboratory to determine the course of vasomotor fibers as measured by(More)
A new milestone in the development of knowledge of metabolic processes was reached in 1934 when the late Rudolf Schoenheimer turned to the use of stable isotopic elements as a label in organic compounds. By this technic it became possible to follow the metabolic pathways of biologically important compounds; since although isotopic-containing substances are(More)
It is interesting that the last decade has seen a revival of interest in the most fundamental of all biological problems, that of organization. This book is a new attempt to solve this problem. Beginning with a critique of the difficulties inherent in the experimental approach to living beings and the statement of a conviction that the answer to(More)
Since 1974 Biolox ceramic femoral ball heads have been used successfully for artificial modular hip joints. The revision rate due to ball head fracture is lower than 0.02%. This is an extremely low value. In this article it is shown how the safety of a ceramic ball head can be improved using the procedures of HIPing, engraving by laser technique, and 100%(More)
To ensure the stability of ceramic ball heads of hip joint prostheses over the long term, both standards for the material and FDA-regulations for the components have been established. In this paper the philosophy underlying design and reliability is discussed. On the basis of fracture loads determined for Biolox ball heads the high level of stability and(More)