• 한국임상수의학회지
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• 제13권2호
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• pp.158-162
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• 1996

Comet assay 는 포유류 세포에서 DNA의 파괴를 측정하는데 있어 신속하고 단순하며 시각적이고 민감한 방법이다. Apoptosis에서는 세포핵의 광범위한 DNA의 붕괴가 일어나므로 comet assay는 종양세포에서 apoptosis가 발생되었는가를 알아내는데 유용하다. 본 연구는 apoptosis 연구의 결과가 변화되지 않도록 comet assay slides를 좀 더 오래 보관할 수 있는 방법을 개발하고자 시행되었다. 개의 종양세포를 가지고 alkali comet assay를 끝낸 뒤 slides를 진공 건조기에서 꺼내서 증류수로 점적하여 10-20분간 침수시키고 현광현미경하에서 육안적으로 관찰하였다. 건조후 3-4일, 1주, 2주, 3주, 4주 및 7주의 slides에서 apoptosis 회복율(%)은 각각 98.1, 98.3, 99.4, 80.8 및 35.2%이었다. 3주 이내의 slides에서 대조군과 비교하여 apoptosis 회복율에서 차이가 없었으나 4주 이상의 slides를 건조후 침수시키는 방법을 이용하였을 때 apoptosis 평가에서 건조 후 3주간까지는 처음의 결과와 차이가 없으며, 이 방법을 이용하여 comet slide의 좀 더 긴 기간이 보관과 보관후의 재평가에서 이용될 수 있는 좋은 방법이 된다.

• 한국수산과학회지
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• 제32권5호
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• pp.556-562
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• 1999

전분은 종류에 관계없이 첨가량을 증가시킴에 따라 gel 강도는 저하하였으며, RA급 냉동 surimi은 전분의 종류에 큰 영향을 받지 않은 반면, A급은 감자전분 및 수식 옥수수전분이 농도 증가에 따른 gel 강도 감소에 가장 적은 영향을 미치는 것으로 나타났다. WPC, DEW 및 SPI는 첨가량이 증가함에 따라 gel 강도는 감소하였으나, BPP는 gel 강도를 증가시키는 것으로 나타났으며, 이 같은 효과는 RA급에서 현저하였다. BPP의 gel 강도 증가 효과는 낮은 변성온도와 열 변성에 따른 구조 변화가 어육 gel의 matrix 강화에 영향을 미치는 것으로 판단된다. RA급을 이용한 어육 gel 제조시 백색도에 큰 영향을 미치지 않는 $2\%$ 범위 내에서 gel 강도 강화를 위해 사용할 수 있는 것으로 나타났다. Gel 강도 1000$\times$g를 제한 인자로 하였을 때, 냉동 surimi의 소모량이 가장 적은 formulation은 A급에서는 A급 surimi $37.8\%$ DEW $6.6\%$, 전분 $3.4\%$ 였으며, RA급에서는 RA급 surimi $40.9\%$, DEW $9.1\%$, 전분 $0.9\%$이었다.

• 한국축산식품학회:학술대회논문집
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• 한국축산식품학회 2004년도 정기총회 및 제33차 춘계 학술대회
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• pp.384-387
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• 2004

The purpose of the present investigation was to develop a novel method for cell immobilization. Aureobasidium pullulans cells were mixed with an alginate solution, and the mixture was extruded to form small gel beads as hydrated- immobilized cells. The beads were then placed at $-15^{\circ}C$ for 6-24 h to induce freeze-dehydration. The freeze-dehydration resulted in shrinkage of beads due to water removal reducing bead volume by 82% and bead weight by 85%. The dehydrated beads were successfully used for the production of fructo-oligosaccharides in a model reactor system. This study showed that bioreactor performance can be improved up to 2 times by the use of the dehydrated beads.

• 한국주조공학회지
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• 제14권6호
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• pp.499-507
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• 1994

The effect of sodium gluconic acid on the collapsability of the sodium silicate type $CO_2$ mold was studied. The bending strength was saturated with gassing $CO_2$ for 60 sec. under $1kg/cm^2$ and with the flow rate of $10\;{\ell}\;/min$. It was decreased with aging after having been fully hardened. The retained strength was reduced in the heating temperature range of $100{\sim}1,100^{\circ}C$ and the retained strength peak near the heating temperature of $100^{\circ}C$ was removed by the effect of the sodium gluconic acid. Silica gel, $Na_2CO_3$ and dehydrated sodium silicates were formed from the binder of sodium silicate with the addition of sodium gluconic acid at the heating temperature of $100^{\circ}C$. $Na_4SiO_4$ was formed by the reaction of $Na_2O$, from decomposed $Na_2CO_3$, with the dehydrated sodium silicate at $500^{\circ}C$. The crystobalite type of $SiO_2$ was formed at $900^{\circ}C$. The sodium gluconic acid had no effect on the bending strength at around $1,100^{\circ}C$ due to the combustion loss of it.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2002년도 제9차 국제심포지움 및 추계정기학술발표회
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• pp.53-53
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• 2002

Shoot tips of in vitro propagated plantlets were cryopreserved using encapsulation/dehydration procedures. Shoot tips were excised under filter sterilized antioxidants solution (0.2M phosphate buffer, pH 5.7 supplemented with 5g/1 ascorbic acid and 15g/1 sodium borate). They were drawn up into a sterile 10 $\textrm{cm}^3$disposable pipette and were dropped into the culture medium with 2.5w/v Na-alginate, then into 100mM CaCl$_2$.2$H_2O$. Encapsulated shoot tips were transferred into 10㎤ of liquid culture medium with a range of sucrose concentrations (0.25-1.0M) and were incubated in dark for 24 hours in 18C at 40rpm. Beads were then dehydrated in silica gel for different time intervals (1-24 hours). Then they were freeze dried either rapidly (plunge directly into liquid N2 or in two stages (samples were kept at 20C for 10 minutes, then reduced to 35C at 1C per minute. Then, plunge into liquid $N_2$). The influence of sucrose and silica gel pre-treatment on pre- and post-freeze shoot growth was examined.(중략)

• 한국재료학회지
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• 제22권5호
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• pp.249-252
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• 2012

Fe doped $TiO_2$ nanoparticles were prepared under high temperature and pressure conditions by mixture of metal nitrate solution and $TiO_2$ sol. Fe doped $TiO_2$ particles were reacted in the temperature range of 170 to $200^{\circ}C$ for 6 h. The microstructure and phase of the synthesized Fe doped $TiO_2$ nanoparticles were studied by SEM (FE-SEM), TEM, and XRD. Thermal properties of the synthesized Fe doped $TiO_2$ nanoparticles were studied by TG-DTA analysis. TEM and X-ray diffraction pattern shows that the synthesized Fe doped $TiO_2$ nanoparticles were crystalline. The average size and distribution of the synthesized Fe doped $TiO_2$ nanoparticles were about 10 nm and narrow, respectively. The average size of the synthesized Fe doped $TiO_2$ nanoparticles increased as the reaction temperature increased. The overall reduction in weight of Fe doped $TiO_2$ nanoparticles was about 16% up to ${\sim}700^{\circ}C$; water of crystallization was dehydrated at $271^{\circ}C$. The transition of Fe doped $TiO_2$ nanoparticle phase from anatase to rutile occurred at almost $561^{\circ}C$. The amount of rutile phase of the synthesized Fe doped $TiO_2$ nanoparticles increased with decreasing Fe concentration. The effects of synthesis parameters, such as the concentration of the starting solution and the reaction temperature, are discussed.

• Journal of Microbiology and Biotechnology
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• 제21권1호
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• pp.62-70
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• 2011

The antibacterial effects of nine lactic acid bacteria (LAB) against Campylobacter jejuni were investigated by using agar gel diffusion and co-culture assays. Some differences were recorded between the inhibition effects measured with these two methods. Only two LAB, Lb. pentosus CWBI B78 and E. faecium THT, exhibited a clear anti- Campylobacter activity in co-culture assay with dehydrated poultry excreta mixed with ground straw (DPE/GS) as the only growth substrate source. It was observed that the supplementation of such medium with a cellulase A complex (Beldem S.A.) enhanced the antimicrobial effect of both LAB strains. The co-culture medium acidification and the C. jejuni were positively correlated with the cellulase A concentration. The antibacterial effect was characterized by the lactic acid production from the homofermentative E. faecium THT and the lactic and acetic acids production from the heterofermentative Lb. pentosus CWBI B78. The antagonistic properties of LAB strains and enzyme combination could be used in strategies aiming at the reduction of Campylobacter prevalence in the poultry production chain and consequently the risk of human infection.

• 한국세라믹학회지
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• 제52권1호
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• pp.48-55
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• 2015

Hardened cement-based materials exposed to the high temperatures of a fire are known to experience change in the pore structure as well as microstructural changes that affect their mechanical properties and tend to reduce their durability. In this experimental investigation, hardened Portland cement pastes were exposed to elevated temperatures of 200, 400, 600, 800, and $1000^{\circ}C$ for 60 minutes, and the resulting damage was studied by thermogravimetry (TG), mercury intrusion porosimetry (MIP) and density measurements. These results revealed that the residual compressive strength is increased at temperatures greater than $400^{\circ}C$ due to a small pore size of 3 nm and/or rehydration of the dehydrated cement paste. However, a loss of the residual strength occurs at temperatures exceeding 500 and $600^{\circ}C$. This can be attributed to the decomposition of hydrates such as portlandite and to an increase in the total porosity.

• Geomechanics and Engineering
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• 제17권5호
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• pp.445-452
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• 2019

Gel-type biopolymers have recently been introduced as environmentally friendly soil binders and have shown substantial strengthening effects in laboratory experimental programs. Although the strengthening effects of biopolymer-treated sands have been verified in previous direct shear tests and uniaxial compression tests, there has been no attempt to examine shear behavior under different confining stress conditions. This study therefore aimed to investigate the strengthening effects of biopolymer-treated sand using laboratory triaxial testing with a focus on confining pressures. Three representative confining pressure conditions (${\sigma}_3=50kPa$, 100 kPa, and 200 kPa) were tested with varying biopolymer contents ($m_{bp}/m_s$) of 0.5%, 1.0%, and 2.0%, respectively. Based on previous studies, it was assumed that biopolymer-treated sand is susceptible to hydraulic conditions, and therefore, the experiments were conducted in both a hydrated xanthan gum condition and a dehydrated xanthan gum condition. The results indicated that the shear resistance was substantially enhanced and there was a demonstrable increase in cohesion as well as the friction angle when the biopolymer film matrix was comprehensively developed. Accordingly, it can be concluded that the feasibility of the biopolymer treatment will remain valid under the confining pressure conditions used in this study because the resisting force of the biopolymer-treated soil was higher than that in the untreated condition, regardless of the confining pressure.

• Applied Biological Chemistry
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• 제39권4호
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• pp.274-281
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• 1996

어류껍질을 식용 젤라틴의 원료로 이용할 목적으로 붕장어 껍질을 시료로 한 젤라틴의 제조조건과 적정 조건으로 제조한 젤라틴의 특성에 대하여 검토하였다. 붕장어 껍질 젤라틴의 적정 제조조건은 다음과 같았다. 탈지 붕장어껍질을 1% 수산화칼슘 현탁액에 2일 동안 침지한 다음 수세 및 탈수하고, 전처리 껍질에 대하여 8배의 증류수를 가하여 $50^{\circ}C$에서 2시간 동안 추출한 다음 원심분리 및 감압여과한다. 이를 양이온(Amberlite IR 900) 및 음이온(Amberlite 200C) 교환수지로 통과시키고, 이어서 정제 젤라틴용액을 농축한 다음 건조한다. 시제품 붕장어껍질 젤라틴의 겔강도, 졸화온도, 겔화온도 및 색차와 같은 물리적 특성값은 각각 240.5g, $28.0^{\circ}C,\;21.0^{\circ}C$ 및 20.5이었고, 용해도, 지방흡수력, 유화성 및 유화안정성과 같은 기능적 특성값은 각각 56.8%, 1.8ml/g, 55.0% 및 48.5%이었으며, 수율은 약 49%이었다. 붕장어점질 젤라틴으로 제조한 유화물을 6% 혼합하여 만든 연제품은 유화물 무첨가 연제품에 비하여 색조를 제외한 개선효과는 없었다. 붕장어껍질 젤라틴을 연제품의 품질개량제로 사용하기 위하여는 제조방법의 개선이나 수식 등의 처리가 이루어져야 하리라 판단되었다.