• Journal of Korean Society for Atmospheric Environment
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• v.24 no.3
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• pp.346-356
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• 2008

Asbestos is the name of a group of minerals with long and thin fibers that originate naturally in the environment. Asbestos mainly affects lungs and the membrane that surrounds the lungs. In general, PCM (phase contrast microscopy) and PLM (polarized light microscopy) have been used to analyze asbestos fibers. However, these methods have often problems to over-estimate number concentration when counting real asbestos fibers. Moreover, there are many difficulties when separating and identifying various asbestos and non-asbestos fibers. In order to determine quantitative information on fibrous particles, source profiles for asbestos and non-asbestos fibers must be initially developed on the basis of their chemical compositions and physical parameters. In our study, a SEM/EDX was used to develop source profiles from known asbestos samples as reference samples. We could make the source profile matrix consisting of 6 types of asbestos fibers and 2 types of non-asbestos fibers by analyzing 380 fibers. Based on these profiles, a rule building expert system was developed by using the visual basic application (VBA). Various fibers were successfully classified by 2 simple rules in the EXCEL environment based on several visual steps such as inserting data, viewing results, and saving results. For a case study to test the expert system, samples from a construction materials and from various indoor environments such as a residental area, a preschool classroom, and an underground store were collected and analyzed. As a result of the survey, a total of 76 individual test fiber particles was well classified into 5 different types of particle classes; 9.3% of chrysotile, 15.4% of amosite, 0.8 of crocidolite, 4.2% of tremolite, 5.8% glass fiber, 21.1% of other fibers, and 43.5% of unknown fibers in terms of number concentration. Even though unknown portion was high, it will be decreased markedly when expanding fiber source profiles.

• Journal of the Korean Ceramic Society
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• v.45 no.10
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• pp.618-624
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• 2008

Various calcium phosphate bioceramics are distinguished by their excellent biocompatibility and osteoconductivity. Especially, the exceptional biodegradability of $\beta$-TCP makes it a bone graft substitute of choice in many clinical applications. The activation of osteoclasts, differentiated from macrophage precursor cells, trigger a cell-mediated resorption mechanism that renders $\beta$-TCP biodegradable. Based on this evidence, we studied the biodegradation process of granular-type $\beta$-TCP bone graft substitute through in vitro and in vivo studies. Raw 264.7 cells treated with RANKL and M-CSF differentiated into osteoclasts with macrophage-like properties, as observed with TRAP stain. These osteoclasts were cultured with $\beta$-TCP nano powders synthesized by microwave-assisted process. We confirmed the phagocytosis of osteoclasts by observing $\beta$-TCP particles in their phagosomes via electron microscopy. No damage to the osteoclasts during phagocytosis was observed, nor did the $\beta$-TCP powders show any sign of cytotoxicity. We also observed the histological changes in subcutaneous tissues of rats implanted with granule-type $\beta$-TCP synthesized by fibrous monolithic process. The $\beta$-TCP bone graft substitute was well surrounded with fibrous tissue, and 4 months after implantation, 60% of its mass had been biodegraded. Also, histological findings via H&E stain showed a higher level of infiltration of lymphocytes as well as macrophages around the granule-type $\beta$-TCP. From the results, we have concluded that macrophages play an important role in the biodegradation process of $\beta$-TCP bone graft substitutes.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.2
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• pp.220-229
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• 2008

Purpose: The present study was aimed to examine the effect of acellular dermal matrix ($AlloDerm^{(R)}$) grafted to the experimental tissue defect on tissue regeneration. Materials and Methods: Male albino rabbits were used. Soft tissue defects were prepared in the external abdominal oblique muscle. The animals were then divided into 3 groups by the graft material used: no graft, autogenous dermis graft, and $AlloDerm^{(R)}$ graft. The healing sites were histologically examined at weeks 4 and 8 after the graft. In another series, critical sized defects with 8-mm diameter were prepared in the right and left iliac bones. The animals were then divided into 5 groups: no graft, grafted with autogenous iliac bone, $AlloDerm^{(R)}$ graft, $AlloDerm^{(R)}$ graft impregnated with rhBMP-2, and $AlloDerm^{(R)}$ graft with rhTGF-${\beta}1$. The healing sites of bone defect were investigated with radiologic densitometry and histological evaluation at weeks 4 and 8 after the graft. Results: In the soft tissue defect, normal healing was seen in the group of no graft. Inflammatory cells and foreign body reactions were observed in the group of autogenous dermis graft, and the migration of fibroblasts and the formation of vessels into the collagen fibers were observed in the group of $AlloDerm^{(R)}$ graft. In the bone defect, the site of bone defect was healed by fibrous tissues in the group of no graft. The marked radiopacity and good regeneration were seen in the group of autogenous bone graft. There remained the traces of $AlloDerm^{(R)}$ with no satisfactory results in the group of $AlloDerm^{(R)}$ graft. In the groups of the $AlloDerm^{(R)}$ graft with rhBMP-2 or rhTGF-${\beta}1$, there were numerous osteoblasts in the boundary of the adjacent bone which was closely approximated to the $AlloDerm^{(R)}$ with regeneration features. However, the fibrous capsule also remained as in the group of $AlloDerm^{(R)}$ graft, which separated the $AlloDerm^{(R)}$ and the adjacent bone. Conclusions: These results suggest that $AlloDerm^{(R)}$ can be useful to substitute the autogenous dermis in the soft tissue defect. However, it may not be useful as a bone graft material or a carrier, since the bone defect was not completely healed by the bony tissue, regardless of the presence of osteogenic factors like rhBMP-2 or rhTGF-${\beta}1$.

• Investigative Magnetic Resonance Imaging
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• v.12 no.1
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• pp.1-7
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• 2008

Purpose : To compare Multi Echo Data Image Combination (MEDIC) and fast SE T2-weighted images with fat saturation (T2FS) to suggest more accurate evaluation of the histologic components of soft-tissue tumors. Materials and Methods : The experimental group included 25 histologic tissues (5 vascular, 4 neural, 4 fibrous, 4 hypercellular, 2 hemorrhagic necroses, 2 cystic, 2 lipoid, 1 myxoid stroma, and 1 thrombus) in 10 patients who had pathologically confirmed schwannoma (n = 3), hemangioma (n = 2), lipoma (n = 1), angiokeratoma (n = 1), synovial sarcoma (n = 1), liposarcoma (n = 1), and malignant fibrous histiocytoma (n = 1). The inhomogeneity values were measured using the standard deviation value (SD) divided by the mean value as SD presents an error amount similar to that of imaging heterogeneity. Results : The inhomogeneity values of 25 histologic components were lower on MEDIC than those on T2FS (p < .001). Conclusion : We conclude that MEDIC is more accurate than T2FS for evaluating the tissue components of soft-tissue tumors using digitalized data because MEDIC images have far lower inhomogeneity.

• Archives of Reconstructive Microsurgery
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• v.11 no.2
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• pp.153-161
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• 2002

Purpose : Plantar surfaces, calcaneal area, and region of Achilles insertion, which are extremely related with weight-bearing area and shoes application, must be reconstructed with glabrous and strong fibrous skin. Numerous methods of reconstructing defects of these regions have been advocated, but the transfer of similar local tissue as a cutaneous flap with preservation of sensory potential would best serve the functional needs of the weight-bearing and non-weight-bearing surfaces of this region. Therefore it is recommended to use the limited skin of medial surface of foot that is similar to plantar region and non-weight-bearing area. In this paper we performed the medial plantar flap transfered as a fasciocutaneous island as one alterative for moderate-sized defects of the plantar forefoot, plantar heel, and area around the ankle in 25 cases and report the result, availability and problem of medial plantar flap. Materials and methods : We performed proximally based medial plantar flap in 22 cases and reverse flow island flap in 3 cases. Average age was $36.5(4{\sim}70)$ years and female was 3 cases. The causes of soft tissue defect were crushing injury on foot 4 cases, small bony exposure at lower leg 1 case, posterior heel defect with exposure of calcaneus 8 cases, severe sore at heel 2 cases, skin necrosis after trauma on posterior foot 4 cases, and defect on insertion area of Achilles tendon 6cases. Average follow up duration was 1.8(7 months-9.5 years) years. Results: Medial plantar flaps was successful in 22 patients. 18 patients preserved cutaneous branches of medial plantar nerve had sensation on transfered flap but diminished sensation or dysesthesia. At the follow up, we found there were no skin ulceration, recurrence of defect or skin breakdown in all 18 patients. But there was one case which occurred skin ulceration postoperatively among another 4 cases not contained medial plantar nerve. At the last follow up, all patients complained diminished sensation and paresthesia at medial plantar area distally to donor site, expecially with 4 patients having severe pain and discomfort during long-time walking. Conclusion : Medial plantar island flap based on medial plantar neurovascualr pedicle have low failure rate with strong fibrous skin and preserve sensibility of flap, so that it is useful method to reconstruct the skin and soft tissue defect of foot. But it should be emphasized that there are some complications such like pain and paresthesia by neuropraxia or injury of medial plantar nerve at more distal area than donor site. We may consider that medial plantar flap have limited flap size and small arc of rotation, and require skin graft closure of the donor defect and must chose this flap deliberately.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.257-261
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• 2005

The microbial cellulose is in a form of three dimensional net structures that consists of 20~50 nm fibrils. It possesses high crystallinity and orientation. It is difficult to synthesize large amount of fibrous carbon nanomaterials by the carbonization process using raw materials such as polyacrylonitrile (PAN), regenerated cellulose (Rayon) and pitch. However, it seems possible thru the application of microbial cellulose as raw material. The application of such cellulose can be further extended to the synthesis of highly oriented graphite fiber. Out of three different cellulose-producing strains, G. xylinus ATCC11142 was chosen as it has the highest productivity (0.066 g dried cellulose/15 mL medium). Tar is often produced during the carbonization of cellulose that limits the formation fibrous structure of the carbonized sample. In order to solve such a problem, pre-studied purification methods of carbon nanotube such as liquid phase oxidation, gas phase oxidation and filtration associated with ultrasonication were applied at the carbonized cellulose. In that case. only by filtration associated with ultrasonication, improved the formation of fiber structure of the carbonized cellulose.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.123-131
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• 1982

The purpose of this study was to observe the responses of the remaining pulp tissue after pulpotomy upon the several kinds of $Ca(OH)_2$ products and the responses of periapical tissue upon some root canal filling materials after extirpation. For pulpotomy, the class V cavities were prepared on the premolars, molars and upper canines, and the pulp was amputated. Each drug was placed over the amputated tissue and cavity was sealed with zinc oxide eugenol cement. The drugs which were used for the study were Dycal (Caulk Co. U.S.A.), Cavitec (Kerr Co. U.S.A.), Calvital, Nobudyne and Neodyne (Neo Dental Chemical Products). For extirpation, the endodontic cavities were prepared on the lingual surfaces of anterior teeth, and the pulp tissues were extirpated as routine method. After enlarging, irrigation, and measuring of root length by taking X-ray, each root canal filling material was filled in the canal with gutta percha cone, and endodontic cavity was sealed with zinc oxide eugenol cement. Zinc oxide eugenol, $Ca(OH)_2$ (Eli Lilly Co. U.S.A.) and Vitapex (Neo Dental Chemical Products) were used as root canal filling materials. Animals were sacrificed after 1, 3 and 6 weeks following the operation. The teeth were decalcified in formic acid, sectioned and stained with hematoxylin eosin. Microscopic examination revealed as follows. 1. Dycal: The dentin bridge formation was observed at the 3rd week after pulpotomy. Inflammatory conditions which were infiltration of inflammatory cells and dilatation of blood vessels were kept in remaining pulp tissue at the 6th week. 2. Calvital: The dentin bridge was observed at the 1st week after pulpotomy. As the time clasped, the pulp tended to be the fibrous degeneration. 3. Cavitec, Nobudyne and Neodyne: In the case of Cavitec and Nobudyne, the incompleted and irregular dentin bridge was observed at the 6th week, and in Neodyne, was observed at the 3rd week. The severe inflammatory changes were seen in the remaining pulp tissue. As the time clasped, the fibrous degeneration tended to spread in the remaining pulp tissue. 4. $Ca(OH)_2$: Osteocementum was formed at the 3rd week, the matrix of cementum and dentin were resorted, and infiltration of lymphocytes was seen in periapical tissue when $Ca(OH)_2$ was used as canal-filling materials. S. ZOE and Vitapex The cementum like substance was seen in periapical portion at the 1st week, when ZOE and Vitapex were used as root canal filling materials. As the time elapsed, the matrix of cementum and dentin tended to be resorted. At the 6th week, the inflammatory condition of periapical tissue was continued in the case of ZOE, but was reduced in the case of Vitapex.

• Journal of the Mineralogical Society of Korea
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• v.21 no.3
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• pp.283-287
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• 2008

The imogolite synthesis wore performed by using tetraethoxysilane (TEOS) and aluminium-sec-butoxide (ASB) at < $100^{\circ}C$. A mixure of TEOS and ASB in a molar ratio of 1:2 was prepared under vigorous stirring and the experiments were performed under the hydrothemal refluxing condition. When the concentration of TEOS and ASB in solution was 0.5 M, a well-crystallized imogolite was synthesized, and the reflections wore shown at d = 22.4, $9.5\;\AA$ etc., after XRD analysis. DTA analysis shows 2 exothemal peaks at 68 and $249^{\circ}C$, suggesting the dehydration and the dehyroxylation reaction, respectively. The result of TG indicates 41% weight loss. And the weak and unsymmetrical peaks by the Si-O-Al stretching vibrations at 953 and $993cm^{-1}$ and by O-Si-O bending vibration at $562cm^{-1}$ were observed after IR analysis. The synthetic imogolite was fibrous and shows a spiders web like network structure.

• Korean Journal of Materials Research
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• v.15 no.5
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• pp.353-360
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• 2005

Surface treatment play an important role in nucleating calcium phosphate deposition on surgical Ti implant. Therefore, the purpose of this study is to examine whether the precipitation of apatite on cp-Ti and Ti alloys are affected by surface modification in HCl and $H_2O_2$ solution. Specimens were then chemically treated with a solution containing 0.1 M HCl and 8.8M $H_2O_2$ at $80^{\circ}C$ for 30 mins, and subsequently heat-treated at $400^{\circ}C$ for 1 hour. All specimens were immersed in the HBSS with pH 7.4 at $36.5^{\circ}C$ for 15 days, and the surface was examined with XRD, SEM, EDX ana XPS. Also, pure Ti, Ti-6Al-4V and Ti-6Al-7Nb alloy specimens with and without surface treatment were implanted in the abdominal connective tissue of mice for 4 weeks. All specimens chemically treated with HCl and $H_2O_2$ solution have the ability to form a apatite layer in the HBSS which has inorganic ion composition similar to human blood plasma. The average thickness of the fibrous capsule surrounding the specimens implanted in the connective tissue was $38.57\;{\mu}m,\;62.27\;{\mu}m\;and\;45.64\;{\mu}m$ in the cp-Ti, Ti-6Al-4V ana Ti-6Al-7Nb alloy specimens with the chemical treatment respectively, and $52.20\;{\mu}m,\;75.62\;{\mu}m\;and\;66.56\;{\mu}m$ in the commercial specimens of cp-Ti, Ti-6Al-4V and Ti-6Al-7Nb without any treatment respectively. The results of this evaluation indicate that the chemically treated cp-Ti, Ti-6Al-4V ana Ti-6Al-7Nb alloys have better bioactivity and biocompatibility compared to the other metals tested.

• Economic and Environmental Geology
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• v.51 no.4
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• pp.309-322
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• 2018

Naturally occurring asbestos (NOA) occurs in rocks and soils as a result of natural weathering and human activities. It is proved that inhalation of asbestos fibers can lead to increase risk of developing several diseases such as lung cancer and malignant mesothelioma. The parent rocks of asbestos have been mainly associated with (ultra)mafic and carbonate rock. The previous studies on NOA were mainly limited to (ultra)mafic rock-hosted asbestos, but studies on carbonate rock-hosted asbestos are relatively rare in S. Korea. Therefore, this study was aimed to examine mineralogical characteristics of carbonate rock-hosted NOA at three sites including Muju and Jangsu, Jeonbuk province and Asan, Chungnam province. Types of rocks at the three sites mainly consisted of Precambrian metasedimentary rocks, carbonate rock, and Cretaceous and Jurassic granites. Asbestos-containing carbonate rock samples were obtained for mineralogical characterization. XRD, PLM, EPMA, SEM and EDS analyses were used to characterize mineralogical characteristics of the carbonate rock-hosted NOA. From the carbonate rock, fibrous minerals were occurred acicular and columnar forms in the three sites. Fibrous minerals were composed of mainly tremolite and associated minerals included possibly asbestos containing materials (ACM) such as talc, vermiculite, and sepiolite. The length and aspect ratios of tremolite were similar to the standard asbestiform (length >$5{\mu}m$, length:width = 3:1). These results indicate that both non-asbestiform and asbestiform tremolite with acicular forms occurred in carbonate rocks at three sites. Geological and geochemical characteristics and mineral assemblages indicate tremolite and associated minerals might be formed by hydrothermal alternation and/or hydrothermal veins of carbonate rocks due to intrusion of acidic igneous rocks.