• 미생물학회지
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• 제53권3호
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• pp.200-207
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• 2017

SA-TSA 복합구를 이용해 폐활성슬러지로부터 VFAs를 생산하고, 이를 발효 기질로 이용해 PHA를 생산하기 위한 실험을 수행하였다. 30%의 SA-TSA 복합구를 처리하였을 때 폐활성슬러지의 가용화 효율이 가장 효과적으로 일어나서 약 3,900 mg/L의 SCOD값을 얻었으며, acetic acid, propionic acid, iso-butyric acid 및 butyric acid를 주성분으로 하는 2,961 mg/L 농도의 VFAs를 얻었다. VFAs를 외부탄소원으로 이용하는 SBR 공정을 통해 PHA를 생합성하는 미생물을 농화배양하는 실험을 수행하고 PCR-DGGE로 분석한 결과, 우점 미생물로 Vibrio spp.와 Corynebacterium glutamicum이 확인되었다. 폐활성슬러지로부터 얻은 VFAs를 탄소원으로 사용하여 농화된 혼합미생물배양체를 회분배양한 결과, 건체량의 25.9%에 달하는 PHB를 얻었다. 본 연구결과는 SA-TSA 복합구를 이용하여 폐활성슬러지로부터 VFAs를 얻음으로써 폐슬러지 감량화 효과를 얻고, 또 혼합미생물배양체를 이용하여 VFAs를 바이오폴리머로 전환함으로써 경제성을 확보할 수 있는 새로운 생물공정의 가능성을 보여준다.

• Restorative Dentistry and Endodontics
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• 제25권4호
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• pp.527-535
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• 2000

The purpose of this study was to evaluate effects of smear layer and dentin primers on the sealing ability of root canals. 126 extracted human teeth with single, straight canals and mature apices were used. The Samples were first classified into six groups as follows: presence of smear layer; absence of smear layer; Scotchbond Bond Multi-Purpose; All Bond 2; Mac Bond 2; Clearfil Liner Bond 2. A Positive control was also established. All teeth except the control group were then obturated with thermoplasticized gutta-percha and AH26. Electrochemical and dye penetration technique were later used to evaluate the degree of micro leakage through the root canal. Seventy teeth were then immersed in a 1% potassium chloride solution and An external power supply(DC 10 V) was then applied to the circuit for the electrochemical microleakage test. The degree of Microleakage was determined over period of 28 days before being evaluated. In total, 48 teeth were submitted to the dye infiltration technique. All specimen were suspended in 2% methylene blue dye for 1 week before being longitudinally split. The degree of dye infiltration was measured under a stereo microscope at ${\times}10$ magnification and evaluated. The results were as follows: 1. Apical microleakage increased throughout the test period in all group and one group having a smear layer showed a dramatic increase under electrochemical test (p<0.05). In the group having smear layer, the degree of apical microleakage was the highest, and the micro leakage was much higher than in the smear layer removed group in electrochemical test (p<0.05). Scotchbond Multi-Purpose, All Bond 2, Mac Bond 2 and Clearfil Liner Bond 2 showed lower micro leakage than one group having smear layer. The All Bond 2 and Clearfil Liner Bond 2 treated groups showed the lowest microleakage in electrochemical test (p<0.05). 2. There was no significant difference between the experimental groups in dye penetration technique. These results suggested that the removal of the smear layer from root canal and concomitantly the application of dentin primer into root canal could improve the sealing ability of root canal obturation.