• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1574-1582
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• 2014

Bacteria recognize changes in their population density by sensing the concentration of signal molecules, N-acyl-homoserine lactones (AHLs). AHL-mediated quorum sensing (QS) plays a key role in biofilm formation, so the interference of QS, referred to as quorum quenching (QQ), has received a great deal of attention. A QQ strategy can be applied to membrane bioreactors (MBRs) for advanced wastewater treatment to control biofouling. To isolate QQ bacteria that can inhibit biofilm formation, we isolated diverse AHL-degrading bacteria from a laboratory-scale MBR and sludge from real wastewater treatment plants. A total of 225 AHL-degrading bacteria were isolated from the sludge sample by enrichment culture. Afipia sp., Acinetobacter sp. and Streptococcus sp. strains produced the intracellular QQ enzyme, whereas Pseudomonas sp., Micrococcus sp. and Staphylococcus sp. produced the extracellular QQ enzyme. In case of Microbacterium sp. and Rhodococcus sp., AHL-degrading activities were detected in the whole-cell assay and Rhodococcus sp. showed AHL-degrading activity in cell-free lysate as well. There has been no report for AHL-degrading capability in the case of Streptococcus sp. and Afipia sp. strains. Finally, inhibition of biofilm formation by isolated QQ bacteria or enzymes was observed on glass slides and 96-well microtiter plates using crystal violet staining. QQ strains or enzymes not only inhibited initial biofilm development but also reduced established biofilms.

• Journal of Microbiology and Biotechnology
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• 제23권2호
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• pp.237-245
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• 2013

Canthaxanthin (cx) is a potent antioxidant that is chemically synthesized at the industrial scale and has imperative applications in the cosmetic and feed industries. An orange pigmented mesophilic bacterium, designated as K44, was isolated from soil samples of Kargil, India. Biochemical tests, 16S rRNA gene sequencing, and FAME analysis of the bacterium indicated it to belong in the genus Dietzia and is distinct from human isolates. The strain showed 98% 16S rRNA gene sequence homology with Dietzia maris DSM 43102. High-performance liquid chromatography profile of the pigments isolated from K44 showed two major peaks absorbing at 465.3 and 475 nm. The liquid chromatography-mass spectrometry (LC-MS) analysis of both these peaks revealed their m/z to be 564. The molecular weights, LC-MS/MS fragmentation patterns, and ${\lambda}_{max}$ of these fractions corresponded to all-trans- (475 nm) and 9-cis-(465.3 nm) cx isomers. The antioxidant activities of cis- and trans-cx isomers isolated from this bacterium were found to differ, where the cis-isomer showed higher free radical, superoxide radical, and reactive oxygen species scavenging activities than the alltrans- isomer, suggesting that 9-cis-cx is more effective as an antioxidant than the all-trans-cx.

• Journal of Microbiology and Biotechnology
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• 제23권4호
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• pp.572-578
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• 2013

Azotobacter vinelandii, a strict aerobic nitrogen-fixing bacterium, has been extensively studied with regard to the ability of $N_2$-fixation due to its high expression of nitrogenase and fast growth. Because nitrogenase can also reduce cyanide to ammonia and methane, cyanide degradation by A. vinelandii has been studied for the application in the bioremediation of cyanide-contaminated wastewater. Cyanide degradation by A. vinelandii in NFS (nitrogen-free sucrose) medium was examined in terms of cell growth and cyanide reduction, and the results were applied for cyanide-contaminated cassava mill wastewater. From the NFS medium study in the 300 ml flask, it was found that A. vinelandii in the early stationary growth phase could reduce cyanide more rapidly than the cells in the exponential growth phase, and 84.4% of cyanide was degraded in 66 h incubation upon addition of 3.0 mM of NaCN. The resting cells of A. vinelandii could also reduce cyanide concentration by 90.4% with 3.0 mM of NaCN in the large-scale (3 L) fermentation with the same incubation time. Finally, the optimized conditions were applied to the cassava mill wastewater bioremediation, and A. vinelandii was able to reduce the cyanide concentration by 69.7% after 66 h in the cassava mill wastewater containing 4.0 mM of NaCN in the 3 L fermenter. Related to cyanide degradation in the cassava mill wastewater, nitrogenase was the responsible enzyme, which was confirmed by methane production. These findings would be helpful to design a practical bioremediation system for the treatment of cyanide-contaminated wastewater.

• Restorative Dentistry and Endodontics
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• 제27권3호
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• pp.257-269
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• 2002

Objective : The purpose of this study was to evaluate the resin infiltration into dentin of one-bottle adhesive systems and self-etching primer bonded to Class V cavities using confocal laser scanning microscope(CLSM). Material and Methods : Forty Class V cavities were prepared from freshly extracted caries-free Human teeth. These teeth were divided into two groups based on the presence of cervical abrasion: Group I, cervical abrasion : Group II, wedge-shaped cavity preparation. Resin-dentin interfaces were produced with two one-bottle dentin bonding systems-ONE COAT BOND(OCB; Coltene$^R$) and Syntac$^R$SPrint$^{TM}$(SS; VIVADENT)-, one self-etching priming system-CLEARFIL$^{TM}$ SE BOND (SB : KURARAY)- and one multi-step dentin bonding system-Scotchbond$^{TM}$Multi-Purpose (SBMP, 3M Dental Products)-as control according to manufacturers' instructions. Cavities were restored with Spectrum$^{R}$(Dentsply). Specimens were immersed in saline for 24 hours and sectioned longitudinally with a low-speed diamond disc. The resin-dentin interfaces were microscopically observed using CLSM. The quality of resin-infiltrated dentin layers were evaluated by five dentists using 0~4 scale. Results : Confocal laser scanning microscopal investigations using primer labeled with rhodamine B showed that the penetration of the primer occurred along the cavity margins. Statistical analysis using one-way ANOVA followed by Duncan's Multiple Range test revealed that the primer penetration of the group 2(wedge-shaped cavity preparation) was more effective than group 1(cervical abrasion) and that of the gingival interfaces was more effective than the occlusal interfaces. In the one-bottle dentin bonding systems, the resin penetration score of OCB was compatible to SBMP, but those of SS and self-etching priming system, SB were lower than SBMP.

• 지구물리와물리탐사
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• 제12권4호
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• pp.355-360
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• 2009

USN (Ubiquitous Sensor Network, 유비쿼터스 무선네트워크) 융합기술을 기반으로 하는 자원탐사 축소모형 시스템을 구축하였다. 실제 환경의 재현을 위해, 비금속 모형판 아래 금속판을 설치하고, 모형판 위에서 이동로봇에 설치된 고정밀 3축 자기센서를 이용하여 실제 자장값을 계측한다. 측정된 자장값은 무선네트워크를 이용하여 이동로봇이 중앙 컴퓨터로 전송한다. 이러한 하드웨어 기반의 테스트 시스템은 현장 상황을 물리적으로 유사하게 재현함으로써, 시뮬레이션의 신뢰도가 높고, USN기반 자원탐사시스템 설계지침을 다각도로 검토할 수 있다. 본 연구에서는 금속물체 탐지시스템을 재현하기 위해, 평판 위에서 이동로봇을 사용하여, 평판 아래에 설치된 금속판의 위치를 탐지하는 실험을 성공적으로 실시하였다.

• 통상정보연구
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• 제13권1호
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• pp.97-120
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• 2011

본 연구의 목적은 고부가가치 창출을 위한 부산항 환적화물 유치 속성과 항만경쟁력이 무엇인지를 밝히고자 하였다. 환적화물 경쟁력을 항만물동량과 시장점유율로 정의하고 환적항만 환경요인을 내부환경과 외부환경으로 구분하여 이들이 미치는 영향을 살펴보았다. 연구결과 최적의 환적항만이 되기 위해서는 내부환경으로 배후규모와 입지, 시설 및 요율이, 외부환경으로는 국제 네트워크와 물류관리 정보화가 물동량증가에 긍정적인 영향을 미치는 것으로 나타났다. 환적화물 유치전략을 극대화하기 위한 방안을 제시하면 첫째 입항에서 하역, 운송, 가공, 선적에 이르는 일괄관리시스템을 구축하여야 한다. 둘째, 관세법에서 규정한 개항을 자유무역지역으로 지정하여 관세 및 내국세 비과세를 통한 외국자본의 유업 및 물동량 증가라는 시스템을 구축하여야 한다. 셋째, 자본의 자유로운 이동을 위하여 불법적인 자본이동을 제외한 외국환거래의 대폭적인 자유화를 보장하여 화주 및 선박회사의 부산항 화물유치 증대 및 투자유치를 적극 추진하여야 한다.

• 한국동물위생학회지
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• 제33권2호
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• pp.97-103
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• 2010

Foot-and-mouth disease (FMD) commonly infects cloven-hoofed livestock animals such as cattle, pig, sheep, and goat and its clinical signs are well-known. Besides livestock, FMD can be transmitted among cloven-hoofed animals in the wild. FMD mostly affects livestock animals in farms, but, wild animals are likely to play a pivotal role in spreading the disease due to their way of free living. In the case of deer, the clinical signs of FMD vary widely from subclinical to severe infections. Thus, in some deer species, it may be hard to verify clinical signs of FMD. A deer may carry the virus up to 11 weeks after exposure, shedding the virus during the period. However, deer is not considered as a typical host for persistent infection like buffalo, cattle or sheep. In Korea, small-scale livestock farms which have less than 10 animals make up 63.6% of the entire livestock farms. Considering raising environment in deer farms, it is assumed that the risk of virus excretion and consequent transmission of FMD among deers is relatively lower than other cloven-hoofed animals. However, Sika deer and Elk which are typical deer species in Korea would manifest mild to subclinical symptoms upon FMD infection. Therefore, laboratory testing is necessary to confirm FMD in these animals because of difficulty in verifying clinical signs and the risk of virus shedding during inapparent infection.

• 콘크리트학회논문집
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• 제22권1호
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• pp.69-76
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• 2010

콘크리트의 수축으로 인한 균열가능성 평가에 있어서 대부분의 경우 콘크리트를 균질한 물질로 가정하는 방식으로 접근하고 있다. 그러나 이러한 방식으로 접근할 경우 불구속조건 하의 콘크리트에서 자기수축으로 인한 미세균열(micro-cracking) 현상을 평가하는 것이 불가능함과 동시에 콘크리트 내부의 균열 발생 현상을 이해하는데 한계가 있다. 이에 이 연구에서는 시멘트 모르타르 시험체를 가지고 실험적으로는 음향방출(acoustic emission) 장비를 사용하여 내부 균열 발생량을 측정 및 평가하였으며, 이론적인 접근방식의 일환으로 실제 모르타르 시험체로부터 구하여진 이차원 이미지를 사용하여 NIST에서 개발한 OOF code로 유한요소해석을 수행하였다. 실험 및 해석 결과, 모르타르의 내부에서 시멘트 페이스트상의 수축 및 골재의 내부구속으로 인하여 발생하는 미세균열 발생 현상을 보다 현실적으로 이해할 수 있었다.

• 대한치과보철학회지
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• 제45권6호
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• pp.795-804
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• 2007

Statement of problem. Nano-scale calcium-phosphate coating on the anodizing titanium surface using ion beam-assisted deposition (IBAD) has been recently introduced to improve the early osseointegration. However, not much is known about their surface characteristics that have influence on tissue-implant interaction. Purpose. This study was aimed to investigate microtopography, surface roughness, surface composition, and wettability of the titanium surface modified by the anodic oxidation and calcium phosphate coating using IBAD. Material and methods. Commercially pure titanium disks were used as substrates. The experiment was composed of four groups. Group MA surfaces represented machined surface. Group AN was anodized surface. Group CaP/AN was anodic oxidized and calcium phosphate coated surfaces. Group SLA surfaces were sandblasted and acid etched surfaces. The prepared titanium discs were examined as follows. The surface morphology of the discs was examined using SEM. The surface roughness was measured by a confocal laser scanning microscope. Phase components were analyzed using thin-film x-ray diffraction. Wettability analyses were performed by contact angle measurement with distilled water, formamide, bromonaphtalene and surface free energy calculation. Results. (1) The four groups showed specific microtopography respectively. Anodized and calcium phosphate coated specimens showed multiple micropores and tiny homogeneously distributed crystalline particles. (2) The order of surface roughness values were, from the lowest to the highest, machined group, anodized group, anodized and calcium phosphate deposited group, and sandblasted and acid etched group. (3) Anodized and calcium phosphate deposited group was found to have titanium and titanium anatase oxides and exhibited calcium phosphorous crystalline structures. (4) Surface wettability was increased in the order of calcium phosphate deposited group, machined group, anodized group, sandblasted and acid etched group. Conclusion. After ion beam-assisted deposition on anodized titanium, the microporous structure remained on the surface and many small calcium phosphorous crystals were formed on the porous surface. Nanoscale calcium phosphorous deposition induced roughness on the microporous surface but hydrophobicity was increased.

• 대한두개안면성형외과학회지
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• 제15권2호
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• pp.70-74
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• 2014

Background: Many options are available to cover a palatal defect, including local or free flaps. The objective of this study was to evaluate the usefulness of palatal mucoperiosteal island flap in covering a palatal defect after tumor excision. Methods: Between October 2006 and July 2013, we identified 19 patients who underwent palatal reconstruction using a palatal mucoperiosteal island flap after tumor excision. All cases were retrospectively analyzed by defect location, size, tumor pathology, type of reconstruction, and functional outcomes. Speech and swallowing functions were evaluated using a 7-point visual analog scale (VAS) score. Results: Among the 19 patients, there were 7 men and 12 women with an age range of 25 to 74 years (mean, $52.5{\pm}14.3$ years). The size of flaps was $2-16cm^2$ (mean, $9.4{\pm}4.2cm^2$). Either unilateral or bilateral palatal island flaps were used depending on the size of defect. During the follow-up period (mean, $32.7{\pm}21.4$ months), four patients developed a temporary oronasal fistula, which healed without subsequent operative. The donor sites were well re-epithelized. Speech and swallowing function scores were $6.63{\pm}0.5$ and $6.58{\pm}0.69$ on the 7-point VAS, indicating the ability to eat solid foods and communicate verbally without significant disability. Conclusion: The palatal mucoperiosteal island flap is a good reconstruction modality for palatal defects if used under appropriate indications. The complication rates and donor site morbidity are low, with good functional outcomes.