• 한국수소및신에너지학회논문집
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• 제12권4호
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• pp.257-265
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• 2001

Placing a hydrogen conducting, methanol impermeable metallic barrier like palladium (Pd) is a well-known method for preventing methanol crossover through solid polymer electrolyte for direct methanol fuel cells (DMFC). Applying a bias potential between the anode and the barrier can further develop this concept so that the hydrogen transfer rate is enhanced. Since hydrogen diffuses in Pd as atomic form while it moves through nafion electrolyte as ion, it has to be reduced or oxidized whenever it passes the interface formed by Pd and the electrolyte. We performed experiments to measure the hydrogen transport through the Pd membrane placed in Nafion electrolyte of hydrogen/oxygen fuel cell (PEMFC). Applying a bias potential between the hydrogen electrode of the cell and the Pd membrane facilitated the hydrogen passage through the Pd membrane. The results show that the cell current measured with the Pd membrane placed reached almost 40 % the value measured with the cell without Pd membrane. It was found that the current flown through the bias path is only a few percent of the cell current.

• Applied Microscopy
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• 제38권2호
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• pp.107-115
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• 2008

콩팥의 모세여과관문은 토리모세혈관, 내피세포, 혈관사이바탕질, 토리바닥막, 발세포로 구성되어 있다. 콩팥의 노화가 일어나게 되면 형태학적 변형이 일어난다고 보고되었는데, 그 중 흰쥐의 경우 생쥐나 사람보다 노화에 따른 토리의 형태가 다양하게 관찰된다는 보고가 있다. 하지만 이런 연구들은 대부분 단면 위주로, 형태변화에 관한 입체적인 연구는 부족한 실정이다. 본 연구에서는 3개월이 지난 성숙한 흰쥐와 24개월이 지난 노화 흰쥐의 토리 모세여과관을 비교하여 그에 따른 형태변화를 광학 및 투과전자현미경을 이용하여 관찰하였으며, 이러한 결과를 바탕으로 연속절편을 통해 컴퓨터 프로그램을 기반으로 한 3차원 재구성을 시행하였다. 그 결과 노화 흰쥐의 토리에서 요공간의 확장, 모세혈관 내피세포의 변형, 토리바닥막의 비대, 혈관사이바탕질의 확장을 관찰할 수 있었다. 또한 3차원 재구성을 시행한 결과 노화 흰쥐의 토리에서 바닥막 경계의 붕괴 현상, 발세포 핵막의 조각화와 분절 양상, 발세포 세포돌기의 부분적인 수축과 세포돌기의 가늘어짐으로 인한 여과틈새의 확장을 관찰할 수 있었다. 이상의 결과로 미루어 볼 때, 노화가 진행되면 토리의 여과관문의 변형으로 인하여 콩팥의 생리학적 역할과 조절이 영향을받을 것으로 사료된다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제21권2호
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• pp.110-119
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• 1999

The principle of guided tissue regeneration (GTR), as applied to bone healing, is based on the prevention of connective tissue from entering the bony defect during the healing phase. This allows the slower bone producing cells to migrate into and reproduce bone within the defect. The principle of guided tissue regeneration has demonstrated a level of success in regenerating bone defect. Several types of membrane barrier, each one with distinct properties, have been utilized to apply this principle in bone regeneration. The purpose of this study is to introduce and discuss the attributes of rubber dam as a barrier membrane and evaluate whether improved bone regeneration can be achieved by GTR using rubber dam. In the 15 New Zealand white rabbits, full-thickness bone defects on three sites of each rabbit calvaria were made. Non membrane group served as a control and experimental group 1 was covered with rubber dam and group 2 covered with Gore-Tex$^{TM}$ membrane. Macroscopic, radiographic, microscopic examinations were made serially on 1, 2, 3, 6, 12 weeks after operation. The results were as follows: 1. Macroscopically, the control site was collapsed and filled with connective tissue throughout the experimental period. But the defects of experimental groups 1 and 2 were filled with bone-like mass and showed the hard consistency on palpation. 2. Radiographically, the early new bone formation appeared similarly from the host bone in groups 1 and 2. 3. Microscopically, there were much connective tissue at the central part of control site but the defect of group 1 and 2 was filled with the mature bony trabeculae on the 12th week. This results suggest that rubber dam can be effectively used as a barrier membrane for guided bone regeneration.

• Archives of Pharmacal Research
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• 제9권3호
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• pp.119-125
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• 1986

Digitonin is a strong hemolysin and glycyrrhizin has protective activity against the deterring effect of other hemolytic saponins. The interaction of these saponins with liposomes was studied as a function of cholesterol in membrane. In the case of multilamellar vesicles, which act as ideal osmometers, digitonin distrupted the barrier function of liposomes composed of phosphatidyl choline, dicetyl phosphate and cholesterol, however, did not influence on cholesterol-lacking liposomes. Glycyrrhizin had similar effect on liposomes irrespective of cholesterol in membrane. In the test with large unilamellar vesicles, digitonin increased the lysis with increasing cholesterol content in membrane, but glycyrrhizin showed no detectable change in cholesterol-containing liposomes. These results suggest that incorporation of cholesterol into liposomes increases the susceptibility to digitonin, resulting in lysis of liposomes, and that the inhibitory effect of glycyrrhizin against other hemolytic saponins in cholesterol-independent.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.85-89
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• 2004

The wave interactions with fully submerged and floating dual buoy/vertical porous membrane breakwaters has been investigated in experimentally to validate the developed theory and numerical method in the previous study, in which multi-domain hydro-elastic formulation was carried out in the context of linear wave-body interaction theory and Darcy's law. It is found that the experimental results agrees well with the numerical prediction. Transmission and reflection can be quite reduced simultaneously especially in the region of long waves. The properly tuned system to incoming waves can effectively dissipate wave energy and also offset each other between incident and scattered waves using its hydro-elasticity and geometry.

• Journal of Periodontal and Implant Science
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• 제25권2호
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• pp.301-320
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• 1995

The purpose of this study was to evaluate a new biodegradable membrane - atelocollagen as a guided tissue regeneration barrier on the dehiscence defects adjacent to the dental implants. 3 beagle dogs were selected for this study and all the mandibular premolars($P_1,P_2,P_3&P_4$) were extracted. Twelve weeks after the extraction, the edentulous ridges were formed to be placed the titanium plasma-sprayed IMZ implants. Four implant osteotomies were performed on each side of the mandible. The osteotomies were placed facially in the edentulous ridges to approximate an actual dehiscence defect as closely as possible, The standardized dehiscence defects were created 3 mm in width and 4 mm in height by osteotomy. A total 24 implants were placed. e-PTFE, ateloco11agen and $Collatape^{(R)}$ were placed to cover the defects and the one defect served as a control, not covered any membrane. By random selection, three dogs were sacrificed at 2 weeks, 4weeks and 8 weeks after fixation with 3% glutaraldehyde. A week before sacrificing, 8-week dog was infused intravenously with oxy-tetracycline 30mg/kg. The left mandibular blocks were used for full decalcified histologic preparation and the right mandibular blocks were selected for undeca1cified preparation, At 2 weeks, the regenerated bone of e-PTFE and atelocollagen groups appeared to be more dense than other groups and the percentage of bone defect fill was highest for e-PTFE and follwed by ateloco1lagen group. However, the $Collatape^{(R)}$ and control groups showed a little new bone formation. $Collatape^{(R)}$ was almost degraded within 2 weeks. At 4 weeks, the regenerated new bone were much greater and denser than at 2 weeks for e-PTFE and ateloco11agen group. Although a part of atelocollagen bagan to be degraded at the margin and surrounded by foreign body giant cells related to foreign body reaction, it was generally intact and the regenerated new bone was shown much more than at 2 weeks. The amount of new bone in $Collatape^{(R)}$ and control groups at 4 weeks were similar to that of 2 weeks group. At 8 weeks, the regenerated bone was matured and observed along the implant fixture. Direct new bone formation and calcium deposits beneath the e-PTFE were observed. No further bone growth was seen in the $Collatape^{(R)}$ and control groups. In reflected fluoromicrcocopic observation, the osteogenic activity was pronounced between e-PTFE membrane and the old bone. High osteogenic activity was also observed in atelocol1agen group. This study suggested that the ateloco11agen as well as e-PTFE could be used for guided tissue regeneration on dehiscence defects adjacent to the dental implants. But the $Collatape^{(R)}$ was completely resorbed within 2 weeks and was not a suitable membrane for guided bone regeneration.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제20권2호
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• pp.112-126
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• 1998

In dentistry, bony defects can be formed by cyst, tumor, inflammation, trauma and surgery in maxilla and mandible. If the overlying soft tissue invades and preoccupies the jaw bony defects, regenerated bony tissue same as adjacent bone can not replace whole space of the defects, thus preventing osteogenesis from occurring. Guided bone regeneration(GBR) is based on the prevention of overlying soft tissue from entering the bony defect during the initial healing periods. E-polytetrafluoroethylene(e-PTFE) is one of an effective and widely used barrier membrane for GBR, but it has the disadvantages such as surgical removal and high price. To overcome such disadvantages of e-PTFE, many investigators have proposed various absorbable barrier membranes. Inexpensive oxidized cellulose($Surgicel^{(R)}$) membrane was shown to have potential for use as an absorbable barrier membrane for regenerative procedure and it would not require surgical removal. The purpose of this study is to investigate the absorption periods of oxidized cellulose at the implant site and usefulness as a mechanical barrier, preventing the ingrowth of the overlying soft tissue into the bony defects. Two bony defects were made in each tibia of a dog using drill and one defect covered with oxidized cellulose and the other covered with periosteum directly as control. The experimental animals were sacrificed at 1st-7th, 10th, 14th, 21th, 28th day postoperatively, Inspection of the specimens was done to evaluate gross changes. Specimens were examined histopathologically by hematoxylin-eosin and Masson's trichrome staining under light microscope. The results were as follows : 1. There was no significant differences of inflammatory reaction between the experimental and the control group. 2. The resorption of oxidized cellulose was almost completed within 14th day. 3. Histologically, bone formation in the experimental group was somewhat more than that of the control group at 10th, 14th, 21th and 28th day postoperatively. The bone forming pattern of the experimental group was more regular than that of the control group. 4. There was no evidence of soft tissue invasion into the bony defect in the experimental group. In conclusion, oxidized cellulose membrane might be used as an alternative absorbable barrier membrane to prevent overlying soft tissue invasion into the bony defects.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 첨단 분리막 연구동향
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• pp.13-35
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• 2004

Metal Complexes in Macromolecules Applications of Polymer Electrolyte Membranes Facilitated Transport in Solid State Roles of Electrolytes in Solar Cells - Electrolytes :ㆍI- and $I_3$-conductor ㆍelectron barrier or hole conductor ㆍelectrochemical redox reaction media ㆍinterfacial contactor for dye, $TiO_2$ and electrode ㆍmechanical separator (omitted)

• 한국결정성장학회지
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• 제25권3호
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• pp.98-104
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• 2015

Titanium barrier membranes are prepared to investigate the effect of surface-treatments, such as machining, electropolishing, anodizing, and electropolishing + TiN coating, on the biocompatibility and physical properties of the membranes. The surface roughness (Ra) of the membrane decreases from machining ($0.37{\pm}0.09{\mu}m$), TiN coating ($0.22{\pm}0.09{\mu}m$), electropolishing ($0.20{\pm}0.03{\mu}m$), to anodizing ($0.15{\pm}0.03{\mu}m$). The highest ductility (24.50 %) is observed for the electropolished Ti membrane. No evidence of causing cell lysis or toxicity is found for the membranes regardless of the surface-treatments. Cell adhesion results of L-929 and MG-63 show that the machined Ti membrane exhibits the highest cell adhesion while the electropolished membrane is the best membrane for the L-929 cell proliferation after 7 days. However, no appreciable difference in MG-63 cell proliferation among variously surface-treated membranes is detected, suggesting that the electropolished Ti membrane is likely to be the best membrane due to the synergic combination of tailored flexibility and excellent fibroblast proliferation.

• 구강회복응용과학지
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• 제33권3호
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• pp.230-237
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• 2017

치간부 골내낭의 치주재생치료는 수술 후 발생할 수 있는 비심미성 때문에 치과의사에게 힘든 과제이다. 본 연구에서는 이러한 문제점을 해결하기 위해 치간부 골내낭의 bovine bone mineral과 enamel matrix derivative (EMD)를 이용한 재생 수술에 골막을 포함한 결합조직 이식을 동반한 임상증례를 소개하고자 한다. 임상적 및 방사선학적인 검사는 술 전과 수술 6개월 이후 시행하였다. 모든 임상 지표들이 개선되었고, 방사선학적 검사에서 골내낭이 감소함을 확인할 수 있었다. 또한, 부가적인 결합조직이식을 통해 치간부 연조직의 증대 및 형태 개선으로 인한 심미성이 증진되는 효과도 확인할 수 있었다.