• 치과방사선
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• 제16권1호
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• pp.41-48
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• 1986

It is known that radiation therapy is a kind of treatment choices of the maxillofacial tumors. This study is designed to investigate the irradiation effects on rat's periodontal tissues as functional tissues which relate to tooth-support, hard tissue formation and destruction. 20 rats (Sprague-Dowley branch, male) were devided into control group of 4 and experimental groupe of 16. Experimental group was singly exposed to Co-60 irradiation with 10 Gy in the head and neck region. Animals were sacrificed on 2 days, 1 week, 2 weeks and 3 weeks after the irradiation. The specimens were observed by histopathological examination employing H-E stain, van-Gieson stain and PA-ACH fluorescent stain. The results were as follows: 1. Cementoblasts and osteoblasts were gradually lost and rearranged along the external surfaces of the cementum and alveolar bone, but osteoclasts were almost not affected. 2. The cell numbers of the periodontal ligament were decreased due to the cellular atrophy and degeneration, but recovered almost normally on the 3rd week after irradiation. 3. The collagen fibers within the periodontal ligament were irregularly oriented, became finer and decreased in number. 4. The vessels of the periodontal ligament were decreased at the initial stage but increased again on the 2nd week after irradiation, and the hemorrhagic appearances, occurred within the tissues, due to the arterial destruction, were lasted until 3 weeks after irradiation. 5. The glycogen within the periodontal ligament was gradually increased and stored in the matrices of the cemental side on the 1st week after irradiation, but recovered almost normally on the 3rd week after irradiation.

• Progress in Superconductivity
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• 제14권2호
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• pp.99-101
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• 2012

Fluorescent yield X-ray absorption fine structure (XAFS) spectroscopy is useful for analyzing local structure of specific elements in matrices. We developed an XAFS apparatus with a 100-pixel superconducting tunnel junction (STJ) detector array with a high sensitivity and a high resolution for light-element dopants in wide-gap semiconductors. An STJ detector has a pixel size of $100{\mu}m$ square, and an asymmetric layer structure of Nb(300 nm)-Al(70 nm)/AlOx/Al(70 nm)-Nb(50 nm). The 100-pixel STJ array has an effective area of $1mm^2$. The XAFS apparatus with the STJ array detector was installed in BL-11A of High Energy Accelerator Research Organization, Photon Factory (KEK PF). Fluorescent X-ray spectrum for boron nitride showed that the average energy resolution of the 100-pixels is 12 eV in full width half maximum for the N-K line, and The C-K and N-K lines are separated without peak tail overlap. We analyzed the N dopant atoms implanted into 4H-SiC substrates at a dose of 300 ppm in a 200 nm-thick surface layer. From a comparison between measured X-ray Absorption Near Edge Structure (XANES) spectra and ab initio FEFF calculations, it has been revealed that the N atoms substitute for the C site of the SiC lattice.

• Archives of Plastic Surgery
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• 제35권3호
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• pp.248-254
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• 2008

Purpose: Human acellular dermal matrix(ADM) is widely used in the treatment of congenital anomalies and soft tissue deficiencies. But it is rapidly degraded in the body and does not provide satisfactory results. There is a need to improve collagen fiber stability through various methods and ultimately regulate the speed of degradation. Methods: The ADMs were added with various cross-linking agents called glutaraldehyde, dimethyl 3,3'-dithiobispropionimidate to produce cross-linked acellular dermal matrices. 1,4-butanediol diglycidyl ether solution was applied with a pH of 4.5 and 9.0, respectively. The stability of cross-linked dermal matrix was observed by measuring the shrinkage temperature and the degradation rates. The cross- and non-cross linked dermis were placed in the rat abdomen and obtained after 8, 12 and 16 weeks. Results: The shrinkage temperature significantly increased and the degradation rate significantly decreased, compared to the control(p<0.05). All of cross-linked dermises were observed grossly in 16 weeks, but most of non-cross linked dermis were absorbed in 8 weeks. Histologically, the control group ADM was found to have been infiltrated with fibroblasts and most of dermal stroma were transformed into the host collagen fibers. However, infiltration of fibroblasts in the experiment was insignificant and the original collagen structure was intact. Conclusion: Collagen cross-linking increases the structural stability and decreases degradation of acellular dermis. Therefore, decrease in body absorption and increase in duration can be expected.

• 한국토양비료학회지
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• 제45권6호
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• pp.867-876
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• 2012

The concentration of veterinary antibiotics in aqueous and sediment matrices was measured in agricultural irrigation ditches bordering several animal-feeding operations (AFOs) and then compared to its concentration in the watershed. Analytical determination in aqueous samples was based on solid phase extraction (SPE) and appropriate buffer solutions were used to extract residuals in sediment samples. Separation and detection of extracted veterinary antibiotics were performed with high performance liquid chromatograph tandem mass spectrometry (HPLC/MS/MS). In general, higher concentrations of antibiotic were observed in the aqueous phase of irrigation ditches, with the highest concentration of erythromycin hydrochloride (ETM-$H_2O$) of $0.53{\mu}g\;L^{-1}$, than in aqueous watershed samples. In contrast, higher concentrations were measured in river sediment than in irrigation ditch sediment with the highest concentration of oxytetracycline of $110.9{\mu}g\;kg^{-1}$. There was a high calculated correlation ( > 0.95) between precipitation and measured concentration in aqueous samples from the irrigation ditches for five of the ten targeted veterinary antibiotics, indicating that surface runoff could be an important transport mechanism of veterinary antibiotics from field to environment. Further, environmental loading calculation based on measured concentrations in aqueous samples and flow information clearly showed that irrigation ditches were 18 times greater than river. This result suggests the likelihood that veterinary antibiotics can be transported via irrigation ditches to the watershed. The transport via surface runoff and likely environmental loading via irrigation ditches examined in this study helps identify the pathway of veterinary antibiotics residuals in the environment.

• Journal of Microbiology and Biotechnology
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• 제15권2호
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• pp.259-264
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• 2005

Transplantation of cultured chondrocytes can regenerate cartilage tissues in cartilage defects in humans. However, this method requires a long culture period to expand chondrocytes to a large number of cells for transplantation. In addition, chondrocytes may dedifferentiate during long-term culture. These problems can potentially be overcome by the use of undifferentiated or partially developed cartilage precursor cells derived from neonatal cartilage, which, unlike chondrocytes from adult cartilage, have the capacity for rapid in vitro cell expansion and may retain their differentiated phenotype during long-term culture. The purpose of this study was to compare the cell growth rate and phenotypic modulation during in vitro culture between adult chondrocytes and neonatal chondrocytes, and to demonstrate the feasibility of regenerating cartilage tissues in vivo by transplantation of neonatal chondrocytes expanded in vitro and seeded onto polymer scaffolds. When cultured in vitro, chondrocytes isolated from neonatal (immediately postpartum, 2 h of age) rats exhibited much higher growth rate than chondrocytes isolated from adult rats. After 5 days of culture, more neonatal chondrocytes were in the differentiated state than adult chondrocytes. Cultured neonatal chondrocytes were seeded onto biodegradable polymer scaffolds and transplanted into athymic mice's subcutaneous sites. Four weeks after implantation, neonatal chondrocyte-seeded scaffolds formed white cartilaginous tissues. Histological analysis of the implants with hematoxylin and eosin showed mature and well-formed cartilage. Alcian blue/ safranin-O staining and Masson's trichrome staining indicated the presence of highly sulfated glycosarninoglycans and collagen, respectively, both of which are the major extracellular matrices of cartilage. Immunohistochemical analysis showed that the collagen was mainly type II, the major collagen type in cartilage. These results showed that neonatal chondrocytes have potential to be a cell source for cartilage tissue engineering.

• 한국음향학회지
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• 제7권4호
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• pp.98-109
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• 1988

본 연구는 이차 볼테라 필터 계수를 연속적으로 변화시키기 위하여 sequential regression (SER) 방법을 이용한 적응 비선형 디지탈 필터링 알고리즘에 대하여 서술하였다. 일반적으로 SER 방법은 Wiener 필터 이론을 볼테라필터에 직접 적용시킬때 생기는 큰 행렬을 역변환시키기 위하여 사용되었다. 그러나, 본 연구에서는 입력신호가 가우시안일 경우, 최소 자승해를 구하기 위하여 SER 방법을 이용하였다. 이 알고리즘에서, 역변환시킬 행렬의 크기는 일반적 접근 방법보다 작게 되기때문에, 일반적 비선형 시스템 인식 기술보다 본 연구에서 제시한 방법의 계산량이 적다. 본 연구에서 제안한 알고리즘의 성능을 검토하기 위하여 시뮬레이션 결과를 구했다.

• 한국물환경학회지
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• 제32권6호
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• pp.628-648
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• 2016

Increased attention has been paid to the presence of veterinary antibiotics in various environmental matrices due to their toxicological behavior in the ecosystem and development of antibiotic-resistant strains of pathogenic bacteria. In the this review, 37 target antimicrobials were selected based on annual sales of antibiotics for livestock in South Korea 2014. Also, extraction and clean-up methods for the determination of the antibiotic residues in liquid samples including water, milk, and honey were comprehensively reviewed in the literature. Solid-phase extraction (SPE) was commonly used as a pre-treatment method for the samples. Most of the analytes were extracted in acidic conditions (2.5~4.0) except for aminoglycosides, which were extracted in neutral conditions (7.0~8.0). ${\beta}-Lactams$ showed the highest recoveries in neutral pH due to their degradation characteristics in acidic media. Starta-X, Oasis HLB, and Oasis MCX were frequently applied as an SPE cartridge and Oasis HLB showed the highest recoveries for the majority of antibiotic classes. The homogenized honey and milk were extracted by mixing with acids for deproteinization. Solids and other interfering substances in the extract were eliminated by centrifugation followed by membrane filtration or SPE before injection into HPLC.

• Membrane and Water Treatment
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• 제9권3호
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• pp.181-188
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• 2018

A sidestream contains the filtrate or concentrate from the belt filter press, filter backwash and supernatant from sludge digesters. The sidestream flow, which heads back into the sewage treatment train, is about 1-3% less than the influent flow. However, the sidestream can increase the nutrient load since it contains high concentrations of phosphorus and nitrogen. In this study, the removal of PO4-P with organic matter characteristics and bacteriological changes during the sidestream treatment via ladle furnace (LF) slag was investigated. The sidestream used in this study consisted of 11-14% PO4-P and 3.2-3.6% soluble chemical oxygen demand in influent loading rates. LF slag, which had a relatively high $Ca^{2+}$ release compared to other slags, was used to remove $PO_4-P$ from the sidestream. The phosphate removal rates increased as the slag particle size decreased 19.1% (2.0-4.0 mm, 25.2% (1.0-2.0 mm) and 79.9% (0.5-1.0 mm). The removal rates of dissolved organic carbon, soluble chemical oxygen demand, color and aromatic organic matter ($UV_{254}$) were 17.6, 41.7, 90.2 and 77.3%, respectively. Fluorescence excitation-emission matrices and liquid chromatography-organic carbon detection demonstrated that the sidestream treatment via LF slag was effective in the removal of biopolymers. However, the removal of dissolved organic matter was not significant during the treatment. The intact bacterial biomass decreased from $1.64{\times}10^8cells/mL$ to $1.05{\times}10^8cells/mL$. The use of LF slag was effective for the removal of phosphate and the removal efficiency of phosphate was greater than 80% for up to 100 bed volumes.

• Journal of Biosystems Engineering
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• 제30권4호
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• pp.202-209
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• 2005

The output of Stirling engine is influenced by the regenerator effectiveness. The regenerator effectiveness is influenced by heat transfer and flow friction loss of the regenerator matrix. In this paper, in order to provide a basic data for the design of regenerator matrix, characteristics of heat transfer and flow friction loss were investigated by a packed method of matrix in the oscillating flow as the same condition of operation in a Stirling engine. As matrices, 6 kinds of steel wires, 4 kinds of combined steel wires, 8 kinds of combined steel wires with screen meshes were used. The results are summarized as follows; Among 6 kinds of steel wires $({\phi}0.7\;mm,\;{\phi}0.9\;mm,\;{\phi}1.2\;mm,\;{\phi}\;1.6\;mm,\;{\phi}2.0\;mm,\;{\phi}2.7\;mm),$ the two steel wires $({\phi}0.7\;mm,\;{\phi}0.9\;mm)$ showed the highest in effectiveness. Among 4 kinds of combined steel wires $({\phi}l.6-{\phi}l.2\;mm,\;{\phi}1.2-{\phi}l.6\;mm,\;{\phi}0.9-{\phi}l.2\;mm,\;{\phi}l.2-{\phi}0.9\;mm),\;the\;{\phi}1.2-{\phi}0.9\;mm$ showed the highest in effectiveness. Among 8 kinds of combined steel wires with screen meshes $(150-{\phi}0.9\;mm,\;150-{\phi}l.2\;mm,\;{\phi}0.9\;mm-150,\;{\phi}1.2\;mm-150,\;150-{\phi}0.9\;mm-150,\;150-{\phi}1.2\;mm-150,\;150-{\phi}l.6\;mm-150,\;150-{\phi}2.0\;mm-150),\;the\;{\phi}l.2\;mm-150$ showed the highest in effectiveness.

• Journal of Microbiology and Biotechnology
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• 제24권4호
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• pp.534-544
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• 2014

The effects of microbial iron reduction and oxidation on the immobilization and mobilization of copper were investigated in a high concentration of sulfate with synthesized Fe(III) minerals and red earth soils rich in amorphous Fe (hydr)oxides. Batch microcosm experiments showed that red earth soil inoculated with subsurface sediments had a faster Fe(III) bioreduction rate than pure amorphous Fe(III) minerals and resulted in quicker immobilization of Cu in the aqueous fraction. Coinciding with the decrease of aqueous Cu, $SO_4{^{2-}}$ in the inoculated red earth soil decreased acutely after incubation. The shift in the microbial community composite in the inoculated soil was analyzed through denaturing gradient gel electrophoresis. Results revealed the potential cooperative effect of microbial Fe(III) reduction and sulfate reduction on copper immobilization. After exposure to air for 144 h, more than 50% of the immobilized Cu was remobilized from the anaerobic matrices; aqueous sulfate increased significantly. Sequential extraction analysis demonstrated that the organic matter/sulfide-bound Cu increased by 52% after anaerobic incubation relative to the abiotic treatment but decreased by 32% after oxidation, indicating the generation and oxidation of Cu-sulfide coprecipitates in the inoculated red earth soil. These findings suggest that the immobilization of copper could be enhanced by mediating microbial Fe(III) reduction with sulfate reduction under anaerobic conditions. The findings have an important implication for bioremediation in Cu-contaminated and Fe-rich soils, especially in acid-mine-drainage-affected sites.