The dissolution rates of ceramic tricalcium phosphate (TCP) and zinc-containing tricalcium phosphate (ZnTCP) ceramics at pH 5.5 decrease with increasing zinc content. The relative dissolution rates of ceramic ZnTCP with zinc contents of 0.5 and 1.0 mol% are more than three times higher than the relative resorbed volumes of these ZnTCP ceramics which were reported previously. The dissolution rates are likely controlled by only one mechanism, that is polynucleation, in the zinc content range from 0 to 1.0 mol%. Since the surface area of ceramic TCP or ZnTCP is much lower than that of powdered TCP or ZnTCP, the initial dissolution flux of ceramic TCP or ZnTCP remains unchanged for a longer period than that of powdered TCP. As a result, no change in dissolution kinetics is expected during one cycle of osteoclastic resorption. Since neither the dissolution rate nor the change in dissolution kinetics accounts for the previously reported drastic reduction in osteoclastic resorption associated with ZnTCP, it is concluded that the drastic reduction in resorption arises from the suppressive effects of ZnTCP on osteoclast formation or osteoclastic activity.
This study investigated the resorptive activity of osteoclasts on tricalcium phosphate (TCP), zinc-containing tricalcium phosphate (ZnTCP) and magnesium-containing tricalcium phosphate (MgTCP) ceramics in different Zn- or Mg-containing culture media. On the TCP ceramic, an increase in Zn ions in the culture medium within the range between 0.3 and 6.8 ppm significantly induced an increase in osteoclast apoptosis and a decrease in actin ring formation. However, even a high level of Mg ions up to 100 ppm in the culture medium was unlikely to induce an increase in osteoclast apoptosis. Mg ions in the MgTCP ceramics have no effect on osteoclast apoptosis and actin ring formation. There was almost no significant difference in osteoclast apoptosis and actin ring formation between ZnTCP and MgTCP ceramics which have the same solubility and dissolution rates. It is indicated that only an increase in Zn level outside resorption lacuna has an inhibitory effect on osteoclast resorption and that an increase in Zn level inside resorption lacuna could not influence the osteoclast activity.
This paper examines the CPD (charge priming device) ‐ type solid‐state image sensor (MN8210), which has the image size of 2/3 inch, 398 (H) × 496 (V) pixels and horizontal overflow drain structure. Discussions are made on the driving and signal processing methods, which are effective in improving the vertical transfer efficiency and the noise characteristics. By injection driving using externally injected charge, the vertical transfer efficiency can be improved up to 95 percent, independently of the signal magnitude. By using the CDS (correlated double sampling) signal treatment method, the low‐frequency noise component generated in FDA (floating diffusion amplifier) is reduced by approximately 5 dB. By the signal treatment method which picks up only the photosignal component in the two output, waveforms noise reduction of 3 dB could be achieved.
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