• Tribology and Lubricants
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• 제26권2호
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• pp.122-128
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• 2010

Focused Ion Beam (FIB) has been used for site-specific TEM sample preparation and small scale fabrication. Moreover, analysis on the surface microstructure and phase distribution is possible by ion channeling contrast of FIB with high resolution. This paper describes FIB applications and deformed surface structure induced by sliding. The effect of FIB process on the surface damage was explored as well. The sliding experiments were conducted using high purity aluminum and OFHC(Oxygen-Free High Conductivity) copper. The counterpart material was steel. Pin-on-disk, Rotational Barrel Gas Gun and Explosively Driven Friction Tester were used for the sliding experiments in order to investigate the velocity effect on the microstructural change. From the FIB analysis, it is revealed that ion channeling contrast of FIB has better resolution than SEM and the tribolayer is composed of nanocrystalline structures. And the thickness of tribolayer was constant regardless of sliding velocities.

• Preventive Nutrition and Food Science
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• 제1권1호
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• pp.23-29
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• 1996

This study was conducted to investigate the changes in chemical, microbial and sensory characteristics, and antimutagenicity of buchu(leek, Allium odorum) kimchi during fermentation at 15$^{\circ}C$. Reducing sugar contents and pH of buchu kimchi were decreased during the fermentation. The reduction rate of reducing sugar of glutinous rice paste and shrimp added buvhu kimchi(GSBK) was faster than those of control buchu kimchi(CBK) and glutious rice paste added bucku kimchi(GBK). Acidity increased rapidly until 4 days,a nd optimum acidity (0.6%) of bucku kimchi was reached within 2 day. Also total bacterial and lactic acid bacterial counts greatly increased after 4 days of the fermentation. The numbers of lactic acid bacteria after 8 day- fermentation in CBK and GSBK, and 10 day-fermentation in GBK were the highest values, 4.5$\times${TEX}$10^{8}${/TEX} CFU/ml, 4.8$\times${TEX}$10^{8}${/TEX} CFU/ml and 6.1$\times${TEX}$10^{8}${/TEX} CFU/ml, respectively. In the sensory evaluation, appearance of sample was good at 0 day, taste from overall quality of buchu kimchi were asquired the highest values at 6th day. The methanol extracts from buchu kimchi(GBK) showed antimutagenicity against aflatoxin {TEX}$B_{1}${/TEX}({TEX}$AFB_{1}${/TEX})in Salmonella typhimurium TA100. The inhibition ration were 58~69% with treatment of the 5% methanol extracts, and when the adding concentration increased the effect increased.

• 한국초지조사료학회지
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• 제41권1호
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• pp.29-34
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• 2021

본 연구는 근적외선분광법을 활용한 조사료의 Ca과 P 함량의 분석 가능성을 검토하고 예측 정확성이 높은 검량식을 개발하기 위하여 전국 건초 수입상, TMR 회사와 축산 농가에서 수집한 수입 화본과와 두과 목건초 392점 중에서 무작위로 126점을 선택하여 검량식 개발에 이용하였다. 선택된 시료는 시료측정 전처리 방법을 생시료 처리와 건조분쇄 처리구로 나누어 근적외선 스펙트라를 측정하고 근적외선 파장대역을 가시영역, 근적외선, 전파장영역으로 구분하여 검량식을 개발하여 예측 정확성을 평가하였다. 수입건초의 Ca과 P 함량에 대한 예측 정확성은 시료 전처리 방법과 파장대역별에 따라 다양하게 나타났으며, 시료전처리 방법은 건조하여 분쇄하는 방법과 파장대역별로는 근적외선 파장(1,100~2,500 nm)대역에서 예측 정확성이 높게 나타났다. 수입건초의 Ca 함량 예측 정확성은 근적외선 파장대역에서 건조분쇄 측정이 SEC 292.3 mg/kg(R2=0.99)와 SECV 468.6 mg/kg(R2=0.98)로 가장 정확한 예측능력을 나타냈다. 수입건초의 P 함량은 근적외선 파장대역에서 건조분쇄 측정이 SEC 204.4 mg/kg(R2=0.91)과 SECV 224.7 mg/kg(R2=0.89)로 가장 정확한 예측능력을 나타냈다. 이상의 결과를 종합해보면 근적외선분광법을 이용하여 조사료의 주요 광물질인 Ca과 P 함량을 신속하고 정확하게 분석이 가능하였으며, 시료 측정시 건조하여 분쇄하는 전처리 방법과 근적외선 파장대역에서 검량식을 개발하는 것이 예측 정확성이 가장 우수한 것으로 나타났다.

• Mass Spectrometry Letters
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• 제7권1호
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• pp.1-11
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• 2016

Various efforts have been developed to improve sample preparation steps, which strongly depend on hands-on processes for accurate and sensitive quantitative proteome analysis. In this study, we carried out heating the sample prior to trypsin digestion using an instrument to improve the tryptic digestion process. The heat shock generated by the system efficiently denatured proteins in the sample and increased the reproducibility in quantitative proteomics based on peptide abundance measurements. To demonstrate the effectiveness of the protocol, three cell lines (A human lung cancer cell line (A549), a human embryonic kidney cell line (HEK293T), and a human colorectal cancer cell line (HCT-116)) were selected and the effect of heat shock was compared to that of normal tryptic digestion processes. The tryptic digests were desalted and analysed by LC-MS/MS, the results showed 57 and 36% increase in the number of identified unique peptides and proteins, respectively, than conventional digestion. Heat shock treated samples showed higher numbers of shorter peptides and peptides with low inter-sample variation among triplicate runs. Quantitative LC-MS/MS analysis of heat shock treated sample yielded peptides with smaller relative error percentage for the triplicate run when the peak areas were compared. Exposure of heat-shock to proteomic samples prior to proteolysis in conventional digestion process can increase the digestion efficiency of trypsin resulting in production of increased number of peptides eventually leading to higher proteome coverage.

• 한국식품조리과학회지
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• 제24권4호
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• pp.487-493
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• 2008

This study examined barley sprout powder on the quality and preservation of Sulgidduk. An optimized formulation (moisture 18.2%, barley sprout powder 2.0% and sugar 14.8%) was first obtained, and then the affect if incorporating the barley sprout powder as a raw ingredients in the mixture was evaluated in terms of Sulgidduk shelf life and quality. For comparison, a control Sulgidduk sample was prepared using the optimized formulation exclusive of the barley sprout powder. After preparation the samples were stored for 3 days at $20{\pm}1^{\circ}C$. The moisture contents of both samples slightly decreased during storage: however there was no significant difference between the samples. Both samples had decreases in colorimetric L- and a-value attributable to the addition of the barley sprout powder as well as storage. Furthermore the treatment sample had increases in yellowness due to the addition of barley sprout powder and storage while the control sample had decreases in yellowness throughout the storage period. The treatment sample had increasing textural hardness, gumminess, and chewiness as the storage period increased. Finally, the treatment sample had a higher total microbial count for aerobes at the beginning of storage: however, as the storage period progressed the control had greater microbial levels. In conclusion the overall results indicate the addition of barley sprout powder has a preservaion effect on Sulgidduk. This data is expected to contribute to the commercialization of high-quality Sulgidduk products with added nutrition and extended shelf life.

• Applied Microscopy
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• 제31권4호
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• pp.315-323
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• 2001

Kaolinite분말 시료를 이용한 TEM 직접 가열 실험에서 얻은 결론은 아래와 같다. (1) Gatan사의 가열 시료지지대에서 사용하고 있는 증류수 순환장치는 $500^{\circ}C$이상의 가열 실험에서 시료의 유동을 막는 필수적인 장비이다. (2) $600^{\circ}C$이하의 가열 실험에서는 분말의 두께에 따른 상전이 진행정도의 차이가 나타나기 때문에 앙은 시편과 두꺼운 시편을 고루 관찰하는 노력이 필요하다. (3) $900^{\circ}C$ 이상의 고온 가열 실험에서는 융점이 높은 Mo-grid의 사용이 필수적이다. 전체적으로 온도 상승률이나 온도 지속 시간이 상전이 과정에 미치는 영향이 증가하기 때문에 이들의 정량적인 제어가 가능한 자동제어방식의 사용이 필요하다. (4) 단면 관찰을 위해 고온용 epoxy에 포매된 kaolinite분말의 TEM가열 실험은 고온 가열시 epoxy의 유동 문제를 극복할 새로운 방법의 개발이 필요하다.

• Mass Spectrometry Letters
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• 제11권2호
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• pp.36-40
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• 2020

Untargeted metabolomics is a useful tool for drug development focusing on novel chemotherapeutic and chemopreventative agents against cancer cells. In recent years, quadrupole time of flight liquid chromatography-mass spectrometry (Q-TOF LC/MS)-based untargeted metabolomic approaches have gained importance to evaluate the effect of these agents at the molecular level. The researchers working on cell culture studies still do not apply standardized methodologies on sample preparation for untargeted metabolomics approaches. In this study, the rough and wet lysis techniques performed on MCF-7 breast cancer cells were compared with each other via the Q-TOF LC/MS-based metabolomic approach. The C18 and hydrophilic interaction liquid chromatography (HILIC) columns were used for the separation of the metabolites in MCF-7 cell lysates. 505 peaks were detected through the HILIC column and 551 peaks were found through the C18 column for the wet lysis technique. This situation supported by the base peak chromatograms showed that the wet lysis technique allowed us to extract higher number of non-polar metabolites. Almost equal number of metabolites was found for the C18 and HILIC columns (697 peaks for the HILIC column and 695 peaks for the C18 column) when the rough lysis technique was used. However, the intensities of polar metabolites were higher for the rough lysis technique on base peak chromatograms for both the HILIC and C18 columns. Although cell lysis technique, which is the first step in the sample preparation for cell culture studies, does not cause dramatic differences in the number of the detected metabolite peaks, it affects the polar and non-polar metabolite ratio significantly. Therefore, it must be considered carefully especially for in vitro drug development studies.

• 한국미생물·생명공학회지
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• 제49권3호
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• pp.346-355
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• 2021

Ngoc Linh ginseng is one of the most valuable endemic medicinal herbs in Vietnam. In this study, Ngoc Linh ginseng callus was fermented by Lactobacillus plantarum ATCC 8014 (at 6, 7, and 8 log CFU/ml) to evaluate the extraction efficiency of bioactive compounds. The post-fermentation solution was spray-dried using maltodextrin with or without Stevia rebaudiana (3% and 6% v/v) as the wall material. Bioactive compounds such as polyphenols, polysaccharides, and total saponins, and L. plantarum viability during fermentation and after spray-drying, as well as under simulated gastric digestion, were evaluated in this study. The results showed that probiotic density had a significant effect on bioactive compounds, and L. plantarum at 8 log CFU/ml showed the best results with a short fermentation time compared to other tests. The total content of polyphenols, polysaccharides, and saponins reached 5.16 ± 0.18 mg GAE/g sample, 277.2 ± 6.12 mg Glu/g sample, and 4.17 ± 0.15 mg/g sample, respectively after 20 h of fermentation at the initial density of L. plantarum (8 log CFU/ml). Although there was no difference in the particle structure of the preparation, the microencapsulation efficiency of the bioactive compound in the samples containing S. rebaudiana was higher than that with only maltodextrin. The study also indicated that adding S. rebaudiana improved the viability of L. plantarum in gastric digestion. These results showed that S. rebaudiana, a component stimulating probiotic growth, combined with maltodextrin as a co-prebiotic, improved the survival rate of L. plantarum in simulated gastric digestion.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2560-2566
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• 2012

The present study investigates how the thermal stability of retinol (vitamin A) encapsulated in polyester nanoparticles is influenced by the types of polyester used for the nanoparticles. A variety of polyester-retinol nanoparticles were prepared with various polyesters like: poly(ethylene adipate), PEA; poly(butylene adipate), PBA; poly(hexamethylene adipate), PHMA; and three polycaprolactones, PCL, of different molecular weights ($M_n$ ~10, 40, and 80K). The chemical stability of retinol in these nanoparticles, monitored in an aqueous solution at $25^{\circ}C$ and $40^{\circ}C$ for 4 weeks, was high in the following order of the nanoparticles prepared with PHMA > PCL 40K > PCL 10K > PCL 80K > PBA~PEA at $25^{\circ}C$ and PCL 10K > PCL 40K > PHMA > PCL 80K > PEA > PBA at $40^{\circ}C$. More importantly, this study has also found that the thermal stability of the retinol in the nanoparticles was closely connected with the melting temperatures of polyesters and polyester nanoparticles. The results were further discussed with possible factors - such as sample preparation condition (or history) and miscibility between the polyesters and retinol - affecting $T_m$ of the polyesters and the nanoparticles.

• 대한기계학회논문집A
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• 제24권9호
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• pp.2381-2386
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• 2000

Surface replication is playing an important role in the assessment of creep damage and remaining life of high temperature components. As the replication procedures, however, have not been standardized in domestic industry, its standardization is proposed in this study. For this purpose, the 2.25Cr-IMo steel was heat treated(5 min at 1,300 0C and oil quenched) to produce a simulated HAZ microstructure, and crept in air at 575 0C and under 120 MPa to produce artificial cavities. Then, the effect of surface preparation procedures on the quality of replicas was investigated using this sample. As a result, it was demonstrated that the presence of cavities may be observed readily or missed depending on the surface preparation procedures followed. Therefore it is essential to repeat three polishing/etching cycles at least in order to reveal cavitation damage accurately, even though it may be tedious or time-consuming.