Chemically synthesized collagen with a triple helix structure similar to that of natural collagen is attractive as a safe biomaterial. Hybrids of chemically synthesized collagen and apatite are proposed for novel bone substitutes. However their apatite-forming ability in simulated body fluid is still quite low. We examined acceleration of apatite formation on collagen by immobilized poly-γ-glutamic acid (PGA), which has excellent apatite-forming ability. Apatite was formed within 3 days when collagen was treated with PGA solutions containing an appropriate amount of CaCl 2 . A mixture of apatite and calcite was formed at high CaCl 2 concentration. The present results indicate the possibility of preparing hybrid materials, with tailored mechanical and biological properties, based on chemically synthesized collagen.

Recently higher slab cooling capacities have been needed to cope with high speed casting operation over the wide range of water spray rates in the secondary cooling process. However, there are few reports on the cooling capacity of the secondary cooling process, especially the spray thickness and the collision pressure in the casting direction. In this study, laboratory experiments on the cooling capacities of hydraulic and mist spray nozzles are carried under various conditions by developing several kinds of spray nozzles. From the experimental results, in order to achieve a high cooling capacity in a spray nozzle, it is important to select the proper spray thickness and collision pressure when designing the nozzle. As a result, the following new estimation equation for the total heat transfer coefficient is proposed based on a new parameter, that is, the product of spray thickness (Ld) and collision pressure (P). have.=6.21×Ld×P+397. This equation can be used to estimate the cooling capacity of spray nozzles without carrying out experiments with a heated sample plate.

Chemically synthesized collagen with triple helix structure similar to natural collagen has been developed as a safe biomaterial. If the chemically synthesized collagen is deposited with apatite, they are expected for novel bone substitutes having bioactivity and bioresorbability. Although apatite formation on the chemically synthesized collagen has been examined, highly supersaturated condition such as 1.5SBF with ion concentration 1.5 times those of simulated body fluid (SBF) is needed to achieve apatite formation. In the present study, we intended acceleration on the apatite formation on the chemically synthesized collagen by immobilization with polyglutamic acid (PGA). PGA is known as biodegradable and biocompatible polypeptide having excellent apatite-forming ability. We examined effects of the immobilization procedure on mineralization behavior in SBF. At first, PGA was immobilized on porous sponges of chemically synthesized collagen in aqueous solutions containing PGA and CaCl2. As a result, not only apatite but also calcite-type CaCO3 was deposited on the specimens in SBF. The calcite formation was occurred during the treatment with PGA solution. pH of the solution was adjusted to 7 by NaOH solution in order to avoid dissolution of the collagen. During this procedure, Ca (OH)2 would be precipitated by locally increase in pH of the solution and converted into the calcite. When the PGA solution treatment was shortened so as to prevent the calcite formation, single phase of the apatite was formed in SBF. The present results indicate that crystalline phase deposited on the chemically synthesized collagen can be controlled by fabrication procedure, and provide fundamental design of composites containing apatite and chemically synthesized collagen useful for bone regeneration.

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Novel aluminum nitride (AlN) fillers with large particle size and round shape were developed using the carbo-thermal reduction and nitridation (CRN) method in this study. They were used as high thermal conductivity fillers for resin composites. Thermal conductivity of epoxy resin filled with the AlN filler could reach 12 W/m K. The fluidity of the epoxy resin filled with the developed AlN filler was improved to 1.3 times that of conventional resin. Also, viscosity of silicon resin filled with the AlN filler was one tenth lower than the conventional AlN filler. The properties and evaluation of the developed AlN filler for high thermal conductivity packaging material have also been discussed.