• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.190-196
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• 1990

The biological active monomer, 1-(methacryloyloxymethyl)-5-fluorouracil(MAOMFU) was synthesized from 2, 4-bis(trimethylsilyloxy)-5-fluoropyrimidine. Poly(MAOMFU) poly(1-methacryloyloxymethyl-5-f1uorouracil-co-methyl methacrylate), and poly(MAOMFU-co-MMA) were also obtained by radical polymerization at $60^{\circ}C$. The monomer reactivity ratios, $r_1$ and $r_2$ were determined by $Kelen-T\ddot{u}d\ddot{o}s$ method ; $r_1(MAOMFU)=0.72$, and $r_2(MMA)=1.24$. These reactivity values imply that the copolymerization was mainly affected by the steric hindrance of MAOMFU. It was found from kinetic measurements that the rate constants of solvolysis are given as $6.42{\times}10^{-5}sec^{-1}$ and $7.40{\times}10^{-6}sec^{-6}$, respectively, for MAOMFU and poly(MAOMFU).

• Journal of Veterinary Clinics
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• v.24 no.2
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• pp.182-191
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• 2007

Bioabsorbable devices have been utilized and experimented in many aspects of orthopaedic surgery. Depending upon their constituent polymers, these materials can be tailored to provide sufficient rigidity to allow bone healing, retain mechanical strength for certain period of time, and then eventually begin to undergo degradation. The objective of this study was to estimate extent in which Poly-L-latic acid (PLLA) implants had bioabsorbability and biocompatibility with bone and soft tissue in dogs and also to develop bioabsorbable, biocompatible materials with the appropriate strength and degradation characteristics to allow for regular clinical use for treating orthopedic problems in humans as well as animals. Eighteen dogs were used as experimental animals and were inserted two types of PLLA implants. PLLA rods were inserted into subcutaneous tissue of back or the abdomen wall. And the rods were tested for material properties including viscosity, molecular weight, melting point, melting temperature, crystallinity, flexural strength, and flexural modulus over time. PLLA screws were inserted through cortical bone into bone marrow in the femur of the dogs and stainless steel screw was inserted in the same femur. Radiographs were taken after surgery to observe locations of screw. Histological variations including cortical bone response, muscular response, bone marrow response were analyzed over the time for 62weeks. The physical properties of PLLA rods had delicate balances between mechanical, thermal and viscoelastic factors. PLLA screws did not induce any harmful effects and clinical complications on bone and soft tissue for degradation period. These results suggest that PLLA implants could be suitable for clinical use.

• Food Science and Industry
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• v.53 no.1
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• pp.33-42
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• 2020

In accordance with the recent trend of environmentally friendly agricultural policy, product registration of agricultural chitosan among the organic materials has been displayed in various forms such as soil improving agent, crop growth, and pest control. Chitin production industry is expected to bring competitiveness by producing low-quality and low-cost chitin for agriculture, rather than high-quality and high-cost for food, medical products. Since there are various soil microorganisms that can decompose chitin and chitosan in farm soil where crops are produced, it can be applied usefully to agricultural sites suitably for crop growth and pest control using chitin and chitosan as substrates. The purpose of this study is to compare and analyze the registration status of organic materials companies using chitin and chitosan raw materials in the organic materials information system of the NAQS, and to provide an opportunity to further expand the agricultural use of domestic chitin and chitosan.