• 분석과학
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• 제14권1호
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• pp.8-14
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• 2001

환경 시료인 토양, 우유, 해수, 해조류, 어패류, 솔잎 및 해저토 중에 존재하는 $^{90}Sr$의 농도를 결정하기 위한 새로운 형태의 분리농축법을 확립한 후 ICP-AES를 사용하여 각 분석과정을 검토하였다. 처리 과정을 단축시킨 발연 질산법 및 이온교환수지법을 혼합한 새로운 형태의 분석과정으로 $^{90}Sr$의 농도를 정량한 결과 효과적으로 Ca를 완전히 제거할 수 있었으며, 발연질산법 만을 사용했을 경우보다 스트론튬의 회수율이 약 10% 이상 높게 나타났다. 이 방법은 토양, 우유, 해조류, 어패류, 솔잎, 및 해저토 등 환경 시료들 중의 $^{90}Sr$ 결정에 적용할 수 있음을 확인하였다. 분석 결과, 토양 중의 $^{90}Sr$ 농도가 가장 높았으며 모든 시료 중의 $^{90}Sr$의 농도는 환경 기준치 이하로 나타났다.

• 한국자기학회지
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• 제11권4호
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• pp.151-156
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• 2001

최근 망간산화물 Ln$_{1-x}$A$_{x}$MnO$_3$(Ln=La, Pr, Nd등의 lanthannide; A=Ca, Sr, Ba, Pb 등의 +2가 이온)는 초거대자기저항(CMR) 특성으로 많은 연구그룹의 주목을 받고 있다. 그런데 chalcogenide spinels에서도 CMR특성이 관측되는 것으로 보고되고 있다. 본 논문에서는 chalcogenide Ni$_{x}$Fe$_{1-x}$Cr$_2$S$_4$에서 Ni이온이 CMR 특성에 미치는 효과를 X선 회절 실험, 자기저항측정, 그리고 Mossbauer 분광실험으로 조사하였다. 그 결과 Ni이온의 치환은 Jahn-Teller distortion을 심화시키고, 또한 T$_{c}$ 값에 증가를 초래하여 CMR현상에 영향을 준다. T$_{c}$ 부근에서 일어나는 CMR현상은 망간산화물에서의 $Mn^{3+}$ 와 $Mn^{4+}$ 사이의 이중교환상호작용과는 다르게 동적 Jahn-Teller효과에 기인한 도체-반도체전이와 자기장하에서 절반 금속성의 에너지밴드구조를 갖는 시료의 스핀편향에 의한 전도현상 그리고 자기구역의 정렬에 의하여 발생되는 것으로 나타났다.

• 한국동물학회지
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• 제32권1호
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• pp.40-47
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• 1989

계배 근원세포의 배양 배지에 calcium ionophore A23187이나 EGTA를 배양 24시간에 첨가함으로서 초래된 세포내 칼슘 농도의 변화는 근원세포의 분화과정에 상당한 영향을 미쳤다. 배양 24시간에 A23187이나 EGTA를 첨가한 후 배양 48시간, 72시간, 및 96시간에 각각 세포를 [35S]methionine으로 1시간 표지시킨 후 수확하여 2차원 전기영동법으로 단백질을 분리시켰을 때, 일부 단백질은 배양 조건에 따라 합성 양상을 달리함을 보였다. 배양 24시간에 처리한 A23187과 calcium-activated neutral protease는 대조군에 비해 세포융합을 촉진시켰으나 동일 시기에 처리된 phosphoprotein을 정량함으로써 조사하였을 때, A23187이 배양 초기에는 대조군에 비해 약간 이 효소의 활성도를 높이는 효과를 보였으나 세포융합이 완성된 시기인 96시간에는 대조군에 비해 활성도를 높이는 효과를 보였으나 세포융합이 완성된 시기인 96시간에는 대조군에 비해 활성도의 차이를 나타내지 않았다. A23187 및 calcium-activated neutral protease에 의한 세포융합의 촉진, 그리고 A23187에 의한 protein kinase C 활성도의 증가가 모두 근원세포의 융합이 활발히 진행되는 시기인 배양 48-72 시간에 관찰됨을 볼 때, 세포내 칼슘의 농도는 protein kinase C 및 calcium-activated neutral protease와 상호연관을 가지면서 세포분화에 관여하는 것으로 사료된다.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.627-636
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• 2022

In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste is needed to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organic complexing agents such as EDTA cobalt removal can be problematic due to the high stability of the Co-EDTA complex. In this study, the removal of cobalt from NaNO₃ solutions using antimony oxide (Sb₂O₃) synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence of EDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UV-light) and under UV-C irradiation. Ca²⁺ or Ni²⁺ were included in the experiments as competing cations to test the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances the cobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption of cobalt to a higher extent than calcium. Finally, the sorption data collected for Co²⁺ on antimony oxide was modeled using six different isotherm models. The Sips model was found to be the most suitable model to describe the sorption process. The Dubinin-Radushkevich model was further used to calculate the adsorption energy, which was found to be 6.2 kJ mol^-1.

• 한국건설순환자원학회논문집
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• 제12권2호
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• pp.206-213
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• 2024

본 연구는 염소이온이 침투한 시멘트 모르타르에서의 아질산칼슘(Ca(NO₂)₂) 방청제의 방청 효과에 대한 실험적 연구이다. 이를 위하여 아질산칼슘 방청제를 함유한 시멘트 모르타르에 대하여 내부식성과 염화물 이동에 대한 실험을 실시하였다. 그 결과 아질산칼슘 방청제의 사용량을 증가하면 할수록 철근부식에 대한 염화물 임계 농도값이 증가한 반면, 염소이온의 이동속도는 빨라지는 것을 확인하였다. 그러나 아질산칼슘 방청제를 사용한 시멘트 모르타르의 경우 염소이온의 이동속도가 빨라서 부식 발생시간을 단언하는 것은 어려움이 있었다. 그러나 철근부식에 영향을 미치지 않을 아질산칼슘의 사용량은 본 연구의 범위에서는 시멘트 중량 대비 2.0~3.0% 수준의 결과를 나타내었다.

• 환경위생공학
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• 제18권1호
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• pp.58-67
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• 2003

The characteristics of the commercial garbage-decomposing accelerant, Raw Material of Pomia(RMP), Pomia and Vitabio. were analyzed. In HPLC pattern, Pomia and Vitabio showed main peak of about 30kDa in 280nm wave length. RMP, Pomia and Vitabio showed three, two and two peaks in 210nm. K and Na ion content of RMP were 2,620 and 1,590ppm, respectively, and their content were the largest one among others. Ca, Mg and Mn ion content of RMP were also the largest one, but Zn ion content was the least one. $Cl^{-}$, $F^{-}$ and $NO_3^{-}$ ion content of RMP were the largest one, especially $Cl^{-}$ content was 3,553ppm. pH values of RMP and Pomia were in neutral region, but Vitabio was 9.03. Dried residue content of RMP, Pomia and Vitabio were 1.4%, 0.55% and 0.4%, respectively. The number of general bacteria on PCA plate from RMP, Pomia and Vitabio were 2.2{\times}10^{6}cfu/ml,{\;}6.5{\times}10^{3}cfu/ml{\;}and{\;}1.1{\times}10^{3}cfu/ml$, respectively. The number of facultative anaerobes of RMP was $4.4{\;}{\times}{\;}10^{4}cfu/ml$, and it was biggest one. Lactobacilli and yeasts were found less than 10cfu/ml at best. The bacterium exists in RMP in high frequency was identified as Bacillus subtilis. Volatile sulfur compound amount of garbage samples treated with Pomia and Vitabio in concentration of 1/500 at $33^{\circ}C$ for 8 days were 1,273ppb and 1,902ppb, respectively, and control showed 3,015ppb. Volatile organic compound amount of the garbage samples treated were 68,312ppb, 124,317ppb and 263,954ppm, respectively. Diethylamine that known as malodor compound were 5,107ppb, 261ppb and 11,124ppb, respectively.

• 한국조경학회지
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• 제15권2호
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• pp.67-78
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• 1987

This study was executed to measure the user\`s impact natural environment in National Park Campsite. Therefore, we choose Mt. Chiak National Park and the campsite in the district of Temple Ku-Ryong as a model of analysis, which is made by ecological approach, the number of the user has influence on the environment near the campsite. The result are as follows : 1. The more the number of users becomes, the more Na, Ca, Mg ion concentration and pH in the soil increase and the less K ion becomes. 2. Litter and humus depth, litter coverage, herb coverage, soil hardness, the surface of the ground layer and tree species numbers, density and coverage of lower layer shows a sensitive reaction to the number of the users. 3. The research shows that the tolerant trees against campsite impact are Lespedeza maximowiczii, Zanthoxylum schinifolium Staphylea bumalda, Smilax sieboldii, Quercus aliena, Euonymus oxyphyllus, Weigela subsessilis and Securinega suffruticosa, and the sensitive trees are Stephanandra incisa, Rubus trichocarpa, Rubus crataegifolius, Rhododendron mucronulatum, Styrax obassia, Acer palmatum, Lindera obtusiloba, Rhododendron suhlippenbachii, Rhus japonica and Callicarpa japonica. 4. The high density of the users made the simplication of a vegetation structure. So, as the number of the user increase the species showed severe heterogeniety between the heavy-use and nonuse site. 5. As considering the landscape management about campsite and surrounding area on the way of analysis of national landscape aspect and succession sere according to ecological aspect, it may be desirable that Pinus densiflora forest be conserved as Pinus densiflora landscape and mixed forest produce natural scenery with succession sere.

• Animal cells and systems
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• 제14권4호
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• pp.245-252
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• 2010

Iron uptake in mitochondria and fractionated mitochondria compartments was studied to understand iron transport in heart mitochondria. The inner membrane is most active in iron uptake. Mitochondrial uptake was dependent on iron concentration and the amount of mitochondria. Iron transport was inversely proportional to pH in the range of 6.0 to 8.0. Iron transport reached a maximum after 30 min of incubation at $37^{\circ}C$. Iron uptake was inhibited by 1 mM ATP and stimulated by 1 mM ADP. The oxidative phosphorylation inhibitor oligomycin inhibited iron uptake, but rotenone and antimycin A did not. The divalent ions $Mg^{2+}$, $Cu^{2+}$, $Mn^{2+}$, and $Zn^{2+}$ suppressed iron uptake at $10\;{\mu}M$ and stimulated it at 1 mM. The divalent ion $Ca^{2+}$ stimulated iron uptake at $10\;{\mu}M$ and suppressed it at 1 mM, competing with iron. The uptake of calcium was stimulated by 10 to $1000\;{\mu}M$ ATP, while iron uptake was stimulated reciprocally by 10 to $1000\;{\mu}M$ ADP, suggesting that these ions have movements similar to those of ATP and ADP.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.237-237
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• 2017

Rice is highly sensitive to salt stress especially in its early growth stage, which thus is one of the major constraints in rice production. In rice plants, salt sensitivity is associated with the accumulation of $Na^+$ in the shoots, especially in the photosynthetic tissues. High salt concentrations in soil cause high $Na^+$ and $Cl^-$ transport to the shoot and preferential accumulation of those ions in older leaves, which decreases $K^+$ in the shoot, photosynthetic activity and grain yield. Salt exclusion capacity at the leaf sheath is therefore considered to be one of the main mechanisms of salt tolerance. In addition, it is suspected that the lamina joint might be involved in the salt transport from leaf sheath to leaf blade. This research aims to determine if leaf sheaths of rice exclude a large amount of $Na^+$ only or other ions such as $K^+$, $Ca^{2+}$, $Mg^{2+}$, and $Cl^-$ as well, to identify tissues in the leaf sheath, which accumulate $Na^+$, and to examine if the lamina joint is involved in the salt exclusion by the leaf sheath. The rice seedlings of salt tolerant genotype FL478 and salt sensitive genotype IR29 were independently treated with NaCl, KCl, $MgCl_2$ and $CaCl_2$, and Taichung 65 and its near-isogenic liguleless line (T65lg) were treated with NaCl. Then, the content of $Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, and $Cl^-$ ions and their specific location were determined using Atomic Absorption Spectrometer, Ion Chromatograph, and Energy Dispersive X-ray Spectroscopy. Results showed that leaf sheaths of FL478 and IR29 accumulated a large amount of $Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, and $Cl^-$ ons, and thus excluded them from leaf blades when treated with high concentration of each salt. When treated with NaCl, the highest $Na^+$ concentration was found in the basal part of leaf sheaths of both cultivars. Moreover, energy-dispersive X-ray spectroscopy revealed that the central parenchyma cells of the leaf sheath were the site where most Na, Cl, and K were retained under salinity in the salt tolerant genotype FL478. Also, the concentration of $Na^+$, $K^+$ and $Cl^-$ ions in leaf sheaths and leaf blades was comparable between T65 and T65lg, indicating that the lamina joint may not be involved in the exclusion of $Na^+$, $Cl^-$ and $K^+$ by the leaf sheath from the leaf blade under salinity. Therefore, we conclude that the central parenchyma cells of basal part of leaf sheath are the site that plays a physiological role to exclude $Na^+$ in the shoots of rice without the involvement of the lamina joint.

• BMB Reports
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• 제44권5호
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• pp.341-346
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• 2011

The single-stranded DNA binding activity of the Escherichia coli RecA protein is crucial for homologous recombination to occur. This and other biochemical activities of ssDNA binding proteins may be affected by various factors. In this study, we analyzed the effect of $CaCl_2$, NaCl and $NH_4NO_3$ salts in combination with the pH and nucleotide cofactor effect on the ssDNA-binding activity of RecA. The studies revealed that, in addition to the inhibitory effect, these salts exert also a stimulatory effect on RecA. These effects occur only under very strict conditions, and the presence or absence and the type of nucleotide cofactor play here a major role. It was observed that in contrast to ATP, ATP${\gamma}$S prevented the inhibitory effect of NaCl and $NH_4NO_3$, even at very high salt concentration. These results indicate that ATP${\gamma}$S most likely stabilizes the structure of RecA required for DNA binding, making it resistant to high salt concentrations.