• 한국환경과학회지
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• 제28권3호
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• pp.291-301
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• 2019

This study was conducted to investigate the effect of salt concentration and turbidity on the inactivation of Artemia sp. by electrolysis, UV photolysis, electrolysis+UV process to treat ballast water in the presence of brackish water or muddy water caused by rainfall. The inactivation at different salt concentrations (30 g/L and 3 g/L) and turbidity levels (0, 156, 779 NTU) was compared. A decrease in salt concentration reduced RNO (OH radical generation index) degradation and TRO (Total Residual Oxidant) production, indicating that a longer electrolysis time is required to achieve a 100% inactivation rate in electrolysis process. In the UV process, the higher turbidity results in lower UV transmittance and lower inactivation efficiency of Artemia sp. Higher the turbidity resulted in lower ultraviolet transmittance in the UV process and lower inactivation efficiency of Artemia sp. A UV exposure time of over 30 seconds was required for 100% inactivation. Factors affecting inactivation efficiency of Artemia sp. in low salt concentration are in the order: electrolysis+UV > electrolysis > UV process. In the case of electrolysis+UV process, TRO is lower than the electrolysis process, but RNO is more decomposed, indicating that the OH radical has a greater effect on the inactivation effect. In low salt concentrations and high turbidity conditions, factors affecting Artemia sp. inactivation were in the order electrolysis > electrolysis+UV > UV process. When the salt concentration is low and the turbidity is high, the electrolysis process is affected by the salt concentration and the UV process is affected by turbidity. Therefore, the synergy due to the combination of the electrolysis process and the UV process was small, and the inactivation was lower than that of the single electrolysis process only affected by the salt concentration.

• 한국축산식품학회지
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• 제29권3호
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• pp.310-316
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• 2009

In this study, the influence of pressure assisted mild thermal inactivation (PAMTI) on E. coli ATCC 10536 was examined at 200 MPa and temperature range of $20-50^{\circ}C$. Inactivation rate significantly increased (p<0.05) as temperature and time increased at 200 MPa. The maximum inactivation (7.91 log reduction) was obtained at $50^{\circ}C$ for 30 min under 200 MPa, which meant the complete inactivation of E. coli ATCC 10536. Inactivation kinetics were evaluated with the first order inactivation rate (k), activation energy ($E_a$), thermal death time (TDT), and z value. Kinetic parameters were significantly (p<0.05) influenced by variation temperature of PAMTI. In this study, the synergistic effect of pressure and temperature were found in the inactivation of E. coli ATCC 10536 through PAMTI.

• Reproductive and Developmental Biology
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• 제41권2호
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• pp.33-40
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• 2017

X-chromosome inactivation is one of the most complex events observed in early embryo developments. The epigenetic changes occurred in female X-chromosome is essential to compensate dosages of X-linked genes between males and females. Because of the relevance of the epigenetic process to the normal embryo developments and stem cell studies, X-chromosome inactivation has been focused intensively for last 10 years. Initiation and regulation of the process is managed by diverse factors. Especially, proteins and non-coding RNAs encoded in X-chromosome inactivation center, and a couple of transcription factors have been reported to regulate the event. In this review, we introduce the reported factors, and how they regulate epigenetic inactivation of X-chromosomes.

• 한국의학물리학회지:의학물리
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• 제17권2호
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• pp.96-104
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• 2006

본 연구자를 위시한 많은 연구자에 의해 칼슘이 N형 칼슘통로의 비활성화를 촉진시킨다는 것이 보고되었다. 그러나 칼슘에 의한 비활성화 촉진 효과가 고전적인 칼슘의존성 기전에 의해 기인하는지는 아직 확실하지 않다. L형 칼슘통로의 칼슘의존성 비활성화기전을 밝히기 위하여 지금까지 사용해온 방법의 하나는 세포내, 외의 칼슘농도를 변화시켜보는 것이다. 그러므로 본 연구에서는 칼슘의존성 비활성화기전의 존재 여부를 알아보기 위하여 2가 양이온을 1가 양이온인 메틸아민($MA^+$)으로 치환하였다. 선행 연구를 통해 우리는 5초 동안의 긴 저분극 자극 시 바륨과 칼슘을 사용하여 얻은 전류에서 모두 빠른 성분(${\tau}{\sim}150ms$)과 느린 성분(${\tau}{\sim}2,500ms$)의 비활성화가 있음을 알 수 있었다. 본 연구에서 세포외 2가 양이온의 농도가 0이 되도록 하였을 때 빠른 비활성화가 소실된 반면 느린 비활성화에는 영향이 거의 없었다. 또한 바륨를 사용하였을 때보다 10 mV씩 과분극시킨 전압에서의 메틸암모늄 전류 데이터를 비교하여 보았을 때 느린 비활성화의 시정수가 서로 잘 일치하였으며 이 시정수는 막전압이 저분극될수록 감소하는 막전압의존성 비활성화의 특성을 보였다. 본 연구결과와 선행연구의 결과를 종합하여 볼 때 세포외 2가 양이온의 존재는 N형 칼슘통로의 빠른 비활성화가 일어나기 위하여 필수적인 조건이며 이러한 2가 양이온의존성 비활성화기전은 기존의 칼슘의존성 또는 막전압의존성 기전과 다르다는 가설을 제안한다.

• 한국환경과학회지
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• 제23권9호
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• pp.1601-1608
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• 2014

Plasma reactor was used for the inactivation of Phytophthora capsici which is phytophthora blight pathogen in aquiculture. Effects of first voltage, second voltage, air flow rate, pH, incubation water concentration were examined. At the low $1^{st}$ voltage, under 80 V, the lag phase was noticed within 30 sec, however, it was not shown over 100 V. The variation of optimum operation condition was not shown by the variation of microorganisms. However, the inactivation rate was different by the variation of species of microorganisms. The inactivation rate and efficiency were increased by the increase of $2^{nd}$ voltage. The highest initial inactivation rate was shown at pH 3 and the rate was decreased by the increase of pH. The inactivation rate increased by the increase of air flow rate, however, it was shown as similar at the rate of 4 L/min and 5 L/min. The inactivation rate was distinctly decreased at the three times concentration of incubation solution comparing at the distilled water and basic incubation solution.

• 한국환경과학회지
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• 제26권4호
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• pp.421-432
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• 2017

In this study, we examined the suitability of ten disinfection models for predicting the inactivation of Artemia sp. via single or combined physical and chemical treatments. The effect of Hydraulic Retention Time (HRT) on the inactivation of Artemia sp. was examined experimentally. Disinfection models were fitted to the experimental data by using the GInaFiT plug-in for Microsoft Excel. The inactivation model were evaluated on the basis of RMSE (Root Mean Square Error), SSE (mean Sum Square Error) and $r^2$. An inactivation model with the lowest RMSE, SSE and $r^2$ close to 1 was considered the best. The Weibull+Tail model was found to be the most appropriate for predicting the inactivation of Artemia sp. via electrolytic treatment and electrolytic-ultrasonic combined treatment. The Log-linear+Tail model was the most appropriate for modeling inactivation via homogenization and combined electrolytic-homogenization treatment. The double Weibull disinfection model was the most suitable for the predicting inactivation via ultrasonic treatment.

• 미생물학회지
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• 제16권2호
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• pp.62-70
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• 1978

Chlorine was used for inactivation of bacteriophage f2 at pH 5.5, 7.5, and 10.0 at $10^{\circ}C$. The inactivation rate phage with chlorine varied depending on the pH value and reaction time. Hypochlorous acid appeared to be the major species of free chlorine for the inactivation. Suevival of the phage treated with chlorine and infectivity of the RNA extracted from the chlorinated phage were examined. The RNA extracted from untreatd phage was chlorinated and its infectivity was assayed. All three samples showed similar rates of inactivation at pH 5.5 and 7.5, but the naked RNA was more susceptible to chlorine at pH 10.0. The rate of inactivation was compared naked RNA was more susceptible to chlorine at pH 10.0. The rate of inactivation was compared with specific and non-specific attachment of the phasge f2. The specific attachment of the phage increased after the phage had been inactivated by extended chlorination. Chlorine may penetrate to the becteriophage f2 by altering the structural integrity of the protein coat, but the main target of free chlorine for inactivation of the phage appeared to be the phage RNA.

• Membrane and Water Treatment
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• 제10권3호
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• pp.231-237
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• 2019

Peroxymonosulfate (PMS) in combination with Cu(II) was examined to inactivate E. coli and MS2 coliphage in natural water. The combined system (i.e., the Cu(II)/PMS system) caused a synergistic inactivation of E. coli and MS2, in contrast with either Cu(II) or PMS alone. Increasing the concentration of PMS enhanced the inactivation of E. coli and MS2, but after a certain point, it decreased the efficacy of the microbial inactivation. In the Cu(II)/PMS system, adding reactive oxidant scavengers marginally affected the E. coli inactivation, but the inhibitory effects of copper-chelating agents were significant. Fluorescent assays indicated that the Cu(II)/PMS system greatly increased the level of reactive oxidants inside the E. coli cells. The sequential addition of Cu(II) and PMS inactivated more E. coli than did adding the two simultaneously; in particular, the inactivation efficacy was much higher when Cu(II) was added first. The observations from the study collectively showed that the microbial inactivation by the Cu(II)/PMS system could be attributed to the toxicity of Cu(I) as well as the intracellular oxidative stress induced by Cu(III) or radical species.

• 한국물환경학회지
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• 제22권4호
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• pp.672-677
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• 2006

Ozone/UV combined process is an effective technique to enhance generation of OH radical which is non-selective and powerful oxidant. The objective of this study is to evaluate the inactivation rates of B. subtilis spores by three candidate processes (ozone alone, UV alone, ozone/UV combined processes) at 4 and $20^{\circ}$ and to investigate the effects of OH radical on inactivation of B. subtilis spores. On the UV alone process, required UV dosages for lag phase and 3-log inactivation of B. subtilis spores were determined as $8.9mJ/cm^2$ and $47mJ/cm^2$. However, the inactivation of B. subtilis spores didn't occured beyond 4.5-log inactivation despite increasing UV dose. The inactivation of B. subtilis spores by ozone alone and ozone/UV combined process was investigated with ozone CT (Concentration of disinfectant ${\times}$ Contact time) concept. As a result, inactivation of B. subtilis spores by ozone/UV combined process was faster than by ozone alone, and especially $CT_{lag}$ value B. subtilis spores in the presence and absence of t-BuOH, OH radical scavenger, was investigated to evaluate effects of OH radical formed during ozone/UV combined process. We found that OH radical plays important roles on inactivation of B. subtilis spores.

• BMB Reports
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• 제32권4호
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• pp.326-330
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• 1999

An aspartase purified from Hafnia alvei was inactivated by diethylpyrocarbonate (DEP) in a pseudo-first-order inactivation. The first-order plot was biphasic. The inactivation process was not saturable and the second order rate constant was $1.3\;M^{-1}s^{-1}$. The inactivated aspartase was reactivated with NH₂OH. The difference absorption spectrum of DEP-inactivated vs native enzyme preparations revealed a marked peak around 242 nm. The pH dependence of the inactivation rate suggests that an amino acid residue having a pK value of 7.2 was involved in the inactivation. L-aspartate, fumarate (substrates), and chloride ion (inhibitor) protected the enzyme against inactivation, indicating that histidine residues for the enzyme activity are located at the active site of this aspartase. Inspection of the presence and absence of $Cl^-$ ion demonstrated that the number of essential histidine residues is less than two. Thus, one or two histidines are in or near the aspartate binding site and participate in an essential step of the catalytic reaction.