계골격근에서 ubiquitin c-terminal hydrolase의 순수분리 및 특성연구

Thesis (master`s)--서울대학교 대학원 :분자생물학과,1995.Maste

다중경로 패킷 전달환경하의 부하 예측을 통한 안정적인 부하 제어 기법

Thesis (master`s)--서울대학교 대학원 :전기·컴퓨터공학부,2001.Maste

과일 주스 내에서의 병원성 미생물 저감화에 대한 옴가열의 효과

학위논문 (석사)-- 서울대학교 대학원 : 식품공학과, 2014. 2. 강동현.The effect of electric field-induced ohmic heating for inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in buffered peptone water (BPWpH 7.2) and apple juice (pH 3.5, 11.8 °Brix) was investigated in this study. BPW and apple juice were treated at temperatures (55, 58, and 60°C) and times (0, 10, 20, 25, and 30s) by ohmic heating and compared with conventional heating. The electric field strength was fixed at 30 V/cm and 60 V/cm in BPW and apple juice, respectively. Bacterial reduction resulting from ohmic heating was significantly different (P 0.05) different, and 36 °Brix apple juice was more effective with respect to product yield. At 60V/cm, peak system efficiency occurred in 48 °Brix apple juice. Although system efficiency of 36 °Brix apple juice at 30V/cm and 48 °Brix apple juice at 60V/cm were significantly (P < 0.05) different, the disparity between those values was only 8%. In addition, 5-log reduction was accomplished in 36 °Brix apple juice at 30V/cm for 60s while it was achieved in 48 °Brix apple juice at 60V/cm within 20s. These results demonstrate that treatment of 48 °Brix apple juice at 60V/cm was the most effective combination with regard to economic and bactericidal considerations.CONTENTS ABSTRACT............................................................................................Ⅲ CONTENTS............................................................................................ Ⅵ LIST OF TABLES..................................................................................Ⅷ LIST OF FIGURES................................................................................Ⅸ I. INTRODUCTION..................................................................................1 II. MATERIALS AND METHODS.........................................................7 2.1. Effect of Electropermeabilization by Ohmic heating for Inactivation of food-borne pathogens in Buffered Peptone Water and Apple juice .....................................................................................................................7 2.1.1. Bacterial cultures and cell suspension...............................................7 2.1.2. Treatment medium and inoculation...............................................8 2.1.3. Experimental apparatus..................................................................9 2.1.4. Ohmic heating treatment and conventional heating treatment....12 2.1.5. Microbial enumeration.................................................................13 2.1.6. Transmission Electron Microscopy.............................................14 2.1.7. Determination of cell membrane damage by PI uptake...............15 2.1.8. Statistical analysis....................................................................... 16 2.2. Optimization of Ohmic heating for inactivation of food-borne pathogens in different concentration of apple juice............................17 2.2.1. Bacterial cultures and cell suspension.........................................18 2.2.2. Sample preparation and inoculation.............................................18 2.2.3. Experimental equipment..............................................................19 2.2.4. Ohmic heating treatment..............................................................22 2.2.5. Microbial enumeration................................................................ 22 2.2.6. System performance coefficient measurement........................... 23 2.2.7. Color and pH measurement........................................................ 24 2.2.8. Statistical analysis........................................................................25 III. RESULTS................................................................................................26 3.1. Effect of Electropermeabilization by Ohmic heating for Inactivation of food-borne pathogens in Buffered Peptone Water and Apple juice concentration of apple juice................................................................26 3.1.1. Comparison of ohmic heating and conventional heating on inactivation of food-borne pathogens in BPW............................26 3.1.2. Comparison of ohmic heating and conventional heating on inactivation of food-borne pathogens in apple juice....................30 3.1.3. Transmission electron microscopy analysis................................34 3.1.4. Relationship between loss of viability and PI uptake after ohmic and conventional heating............................................................36 3.2. Optimization of Ohmic heating for inactivation of food-borne pathogens in different concentration of apple juice...........................42 3.2.1. Temperature profiles of different concentrations of apple juice ...................................................................................................................42 3.2.2. System performance efficiency at different concentrations of apple juices and voltage gradients..............................................46 3.2.3. Effect of ohmic heating for inactivation of food-borne pathogens at different voltage gradient.........................................................49 3.2.4. The influence of ohmic heating on color and pH of apple juice ...................................................................................................................53 IV.DISCUSSION.......................................................................................... 55 V.REFERENCES..........................................................................................65 Ⅵ.국문초록……………………………………………………………73Maste

Fabrication of ZnO Nanorod based Robust Nanogenerator Metal Substrate

We report on the succesful fabrication of ZnO nanorod (NR)-based robust piezoelectric nanogenerators (PNGs) by using Cu foil substrate. The ZnO NRs are successfully grown on the Cu foil substrate by using all solution based method, a two step hydrothermal synthesis. The ZnO NRs are grown along c-axis well with an average diameter of 75~80 nm and length of 1~1.5 μm. The ZnO NRs showed abnormal photoluminescence specrta which is attributed from surface plasmon resonance assistant enhancement at specific wavelength. The PNGs on the SUS substrates show typical piezoelectric output performance which showing a frequency dependent voltage enhancement and polarity dependent charging and discharging characteristics. The output voltage range is 0.79~2.28 V with variation of input strain frequency of 1.8~3.9 Hz. The PNG on Cu foil shows reliable output performance even at the operation over 200 times without showing degradation of output voltage. The current output from the PNG is 0.7 μA/cm2 which is a typical output range from the ZnO NR-based PNGs. These performance enhancement is attributed from the high flexibility, high electrical conductivity and excellent heat dissipation properties of the Cu foil as a substrate.2

Fabrication of ZnO Nanorod/polystyrene Nanosphere Hybrid Nanostructures by Hydrothermal Method for Energy Generation Applications

We report on the successful fabrication of ZnO nanorod (NR)/polystyrene (PS) nanosphere hybrid nanostructure by combining drop coating and hydrothermal methods. Especially, by adopting an atomic layer deposition method for seed layer formation, very uniform ZnO NR structure is grown on the complicated PS surfaces. By using zinc nitrate hexahydrate [Zn(NO3)2 ·6H2O] and hexamine [(CH2)6N4] as sources for Zn and O in hydrothermal process, hexagonal shaped single crystal ZnO NRs are synthesized without dissolution of PS in hydrothermal solution. X-ray diffraction results show that the ZnO NRs are grown along c-axis with single crystalline structure and there is no trace of impurities or unintentionally formed intermetallic compounds. Photoluminescence spectrum measured at room temperature for the ZnO NRs on flat Si and PS show typical two emission bands, which are corresponding to the band-edge and deep level emissions in ZnO crystal. Based on these structural and optical investigations, we confirm that the ZnO NRs can be grown well even on the complicated PS surface morphology to form the chestnut-shaped hybrid nanostructures for the energy generation and storage applications.2