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A new self-hardening paste was made by using a combination of chitosan, hydroxyapatite (HA) granules, ZnO, and CaO. The sol was made by dissolving 0.1 g of chitosan in a solution of 0.1 g malic acid and 2.0 mL physiological saline solution. Mixed with 0.03 g of CaO and 0.04 g of ZnO powders was 2.77 g (55 wt %) of HA granules which had a homogeneous pore distribution and a porosity of 35-48%. The size of the granules was set for 0.1-0.3 mm. Kneading and setting of the paste generated a little amount of heat (32.8 degrees C) as compared with the heat produced by polymethyl-methacrylate (PMMA) bone cement (114.5 degrees C). The pH value of chitosan-HA-hardened composite after setting was nearly equal to that of human plasma (pH 7.4), while that of PMMA bone cement maintained an acid pH of 4.7. Hydroxyapatite granules less than 0.1 mm, 0.1-0.3 mm, or 0.3-0.6 mm were set using chitosan sol. The size of the granules did not influence the compressive strength of the set chitosan-HA-hardened composite. The greatest compressive strength of chitosan-HA-hardened composite was obtained by using 55 wt % of HA granules. The strength of the chitosan-HA-hardened composite was comparable to that of the cancellous bone derived from tibial eminentia, but was considerably lower than that of the PMMA bone cement.

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The gravimetric method is the most popular method for preparing reference gas mixtures with high accuracy. We have designed and manufactured novel mass measurement equipment for gravimetric preparation of reference gas mixtures. This equipment consists of an electronic mass-comparator with a maximum capacity of 15 kg and readability of 1 mg and an automatic cylinder exchanger. The structure of this equipment is simpler and the cost is much lower than a conventional mechanical knife-edge type large balance used for gravimetric preparation of primary gas mixtures in Japan. This cylinder exchanger can mount two cylinders alternatively on the weighing pan of the comparator. In this study, the performance of the equipment has been evaluated. At first, the linearity and repeatability of the mass measurement were evaluated using standard mass pieces. Then, binary gas mixtures of propane and nitrogen were prepared and compared with those prepared with the conventional knife-edge type balance. The comparison resulted in good consistency at the compatibility criterion described in ISO6143:2001.

We used NDIR for this measurement (Siemens, Ultramat 6E). Configuration of analysis system: gas cylinder-> regulator-> MFC-> NDIR-> response comparison-> results Sample cell flow: 800 mL/min, Reference cell flow: 800 mL/min Cell pressure: 1.94 Kg/cm 3 Calibration Standards: The calibration standards for CCQM-K52 were prepared by gravimetric method including 0.93 %mol/mol of Ar in KRISS. Therefore, the matrix is different from that of coordinating Lab., which does not contain Ar. All source gases were analyzed impurities for purity analysis. The primary standards with 0.014% overall uncertainty (k=2) are used.

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We report two cases in which fracture of the tibial metal tray was thought to be due to improper design of the tray and heavy polyethylene wear. The bone beneath the fractured portion of the tray was deficient and had been replaced by granulomatous fibrous tissue including numerous polyethylene wear particles and foreign-body giant cells. Osteolysis occurred as a tissue reaction to these particles.

No abstract