전기전자 및 디스플레이 산업에 다양한 응용이 기대되는 전도성 고분자인 PPP(Polyparaphenylene)는 단순한 구조와 비교적 높은 열적 안정성을 가지고 있으나 전기적 특성은 기존의 물질보다 낮아 그 응용이 더디게 진행되고 있다. 본 연구에서는 전도성 고분자의 전기적 특성을 개선하기 위해 이온주입법을 이용하여 전기전도성을 개선하는 연구를 진행하였다. 5keV에서 30keV 정도의 아주 낮은 에너지를 이용하여 이온을 가속시킴으로서 시편의 특성 열화를 최소화 할 수 있었다. 이온주입법으로 개선된 시편의 전기전도성은 향후 OTFT와 같은 Organic Electronics Device로서의 사용 가능성을 보였으며 이온의 종류와 주입정도에 따라 Thermoelectric power의 크기가 달라지는 반도체 소재로서의 특성을 나타내어 향후 다양한 형태의 소자에 응용될 수 있는 가능성을 확인하였다. 실험으로 확인된 최적의 이온주입에너지는 10keV에서 15keV의 값을 나타내었다.

System L amino acid transporter is a major route for providing living cells with neutral amino acids including several essential amino acids. To elucidate the expression pattern of L-type amino acid transporter 1 (LAT1) in the bone formation process, the expressions of LAT1 and its subunit 4F2 heavy chain (4F2hc) were investigated in the healing process after the implantation of bone graft materials in the calvarial osseous defected rats. Circular calvarial defects (1 cm in diameter) were made midparietally. The rats were divided into 4 groups of 1 control group and 3 experimental groups. In the control group, the defect was only covered with soft tissue flap. In the experimental groups, they were filled with human particulate dentin (particulate dentin group), with plaster of Paris (plaster of Paris group) and with the mixture of human particulate dentin and plaster of Paris with ratio of 2 : 1 by weight (mixture group). The rats were sacrificed at the 1, 2, 4 and 8 weeks after operation and the RT-PCR analysis and immunohistochemical analysis were performed. In the RT-PCR analysis, the mRNAs of LAT1 and 4F2hc were strongly detected in all 4 groups. In the immunohistochemical analysis, at 1 week after operation, the LAT1 protein and its subunit 4F2hc protein were mainly expressed in the osteoblasts, osteocytes and interstitial tissues of the around the defect and inner part of newly forming bone in all 4 groups. The expressions of LAT1 and 4F2hc proteins were decreased at 2 and 4 weeks after operation. The LAT1 and 4F2hc proteins were scarcely expressed at 8 weeks after operation in all 4 groups. These results suggest that the LAT1 and its subunit 4F2hc highly expressed at the early stage of new bone formation and may have an important role in providing cells with neutral amino acids including several essential amino acids at that stage.

Hydroxyapatite(HA) has been widely used as bone substitutes to rehabilitate bone loss area by new bone formation. But there were some problem of bone formation around HAs due to a little space between HAs embedded in bone loss area. The purpose of this study was to observe morphologically new bone formation around HAs mixed with PLGA block (5.5㎜ in diameter, 4 mm in depth) in Newzealand white rabbit tibia. Before 1 week of sacrification, Alizarin red was injected intraperitoneally into rabbit. At 3 day, 1, 2, 4, 10, 18, 32 weeks, bones with HA as control group(CG)and HA mixed with PLGA block as experimental group (EG)were fixed with 10 % neutral formalin, dehydrated, and embedded with Spurr low viscosity resin. After the specimens were cut by 500 ㎛ with slow diamond wheel saw, these were coated with carbon and examined by REM, LSM and qualifative analysis of calcium and phosphorous deposition were done with EPMA. The obtained results were as follows. 1. Both group showed scattered HA around compact bone under REM and little AZ labelled bone under LSM at 3 days. 2. Both group showed active AZ labelled bone, while EG showed higher Ca(calcium) and P(phosphate) deposition than that of CG at 1 wk. 3. There was decreased AZ labelled bone of both group under LSM. REM of EG showed HA associated with new bone from compact bone, while EPMA features showed similar to Ca and P deposition at 1 wk and EG showed higher than that of CG. 4. REM features of both group showed resorbed HA associated with new bone. There was decreased AZ labelled bone of both group under LSM. EPMA features showed higher Ca and P deposition at 4 wks than that of 2 wks. 5. New bone of both group was well demarcated from compact bone under REM at 10 wks. LSM features showed various AZ labelled bone, but weak AZ labelled than that of CG. 6. LSM features of 14 wks showed discontinuous AZ labelled on osteon formation. EPMA of both group showed increased Ca deposition, while there was higher Ca deposition of EG and similar P deposition to CG. 7. REM featureless of 18 wks in EG showed similar gray color to compact bone. LSM features showed osteon formation with little concentric lamellars. EPMA of both group showed increased Ca deposition, while there was higher Ca and P deposition of EG. 8. New bone was ill demarcated from compact bone and increased otseon formation of REM features at 32 wks. There was little AZ labelled bone. EPMA features showed higher Ca and P deposition of EG than that of compact bone. From the aboving results, there was early active AZ labelled bone of both group within 1-2 weeks and since 18 weeks new bone with active osteon formation was poorly demarcated from compact bone. Calcium deposition of EG was early increased than that of CG deposition since 4 weeks after experiments. It was suggested that EG showed active and rapid new bone formation and similar bone mineralization of compact bone