• Applied Microscopy
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• 제20권2호
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• pp.57-70
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• 1990

Characterization and electron microscopic visualization of the plasmid and the gene expression of Escherichia coli were carried out. Transcriptional units of active structural genes were observed after lysis of Escherichia coli cells. The ribosomes attached to the E. coli genome on mRNA molecule as polyribosomes. From this gradient of polyribosome length, we estimated location of mRNA synthesis initiation site. In this experiment, a granule is ofen present which may correspond to a RNA polymerase at the promoter site. pOX1, pOX7, pOX7A, $pOX7{\Delta}1$, pSTP36, pSTP21, pBR322, and pJH12 were visualized by way of electron microscope, and their estimated sizes were determined to be $5.70{\pm}0.08{\mu}m,\;2.15{\pm}0.10{\mu}m,\;2.14{\pm}0.12{\mu}m,\;7.39{\pm}0.08{\mu}m,\;4.03{\pm}0.04{\mu}m,\;1.50{\pm}0.03{\mu}m\;and\;1.25{\pm}0.09{\mu}m$ respectively. One micrometer of measured length corresponded to about 3.0 Kb. Mica-press adsorption method that allows selectivs visualization of the plasmid DNA released in situ from the bacterial cell is rapid and useful for visualization of plasmids. The released plasmid DNA was adsorbed preferently on mica in a divalent cation-free solution. Miller chromatin-spreading method was useful to observe the plasmid and transcripts. BAC method and cytochrome C monolayer were useful to observe the plasmid DNA. Our ability to visualize ultrastructural aspects of the expression of E. coli has given us a unique tool with which to study the regulation the level of an individual gene.

• Asian Journal of Atmospheric Environment
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• 제6권1호
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• pp.14-22
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• 2012

This paper is focused on the comprehensive and detailed interpretation for the chemical transformation of individual Asian dust (hereafter called "AD") particles during long-range transport from source regions to receptor area. A multi-stage particle sampler was operated at a ground-based site in Taean, Korea directly exposed to the outflow of air masses from China during AD period in April 2003. Both quantitative and qualitative analyses for size-classified individual particles were carried out by a microbeam X-ray fluorescence (XRF) method and a microbeam Particle Induced X-ray Emission (micro-PIXE), respectively. Among major characteristic elements, the elemental masses of soil derived components, sulfur, and chloride varied as a function of particle size showing the monomodal maximum with a steeply increasing at 3.3-4.7 ${\mu}m$ particle size. Although the details on chemical composition of AD particle collected on a straight line from source area to our ground-based site are needed, a large amount of Cl coexisted in and/or on AD particles suggests that AD particles collected in the present study might be actively engaged in chemical transformation by sea-salt and other Cl containing pollutants emitted from the China's domestic sources. Through the statistical analyses it was possible to classify individual AD particles into six distinct groups. The internally mixed AD particles with Cl, which has various sources (e.g., sea-salt, coal combustion origin HCl, gaseous HCl derived from the adsorption of acids to sea-salt, and Cl containing man-made particles) were thoroughly fractionated by the elemental spectra drivened by the double detector system of micro-PIXE.

• 한국산학기술학회논문지
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• 제14권12호
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• pp.6575-6580
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• 2013

가혹한 조건에서도 사용할 수 있도록 촉매의 강도세기를 증진시키기 위해 다양하게 촉매를 개질하였다. SCR촉매는 바인더와 분산제를 이용하여 개질하였으며 고정층반응기에서 실험하였다. 개질된 촉매에 대한 수소이용정도, 암모니아 흡착정도를 FT-IR과 $H_2$-TPR을 이용하여 측정하였다. 2.3g의 바인더, 4.7g의 에탄올 그리고 0.1g의 분산제가 SCR촉매에 적절하게 침지된 경우 촉매 강도세기에 있어 약 12%의 증가가 있었다. 그러나 촉매의 강도세기가 증가하는 것에 반해 SCR촉매의 효율은 2~10% 감소하는 경향을 보였다. 그리고 바인더, 분산제, $SiO_2$용액으로 구성된 혼합용액을 촉매에 침지시킬 경우, 촉매의 질소산화물 전환율은 다소 감소하였다. 이는 SCR 반응에 있어 활성점 역할을 하는 Bronsted 산점과 Lewis 산점이 $SiO_2$에 의해 감소하기 때문인 것으로 판단된다.

• 상하수도학회지
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• 제37권6호
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• pp.395-408
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• 2023

This study presents a novel method for addressing the issue of high-concentration contaminants (ammonium, phosphate, antibiotics) in leachate arising from decomposing livestock carcasses. Antibiotics, developed to eliminate microorganisms, often have low biodegradability and can persist in the ecosystem. This research proposes design elements to prevent contamination spread from carcass burial sites. The adsorbents used were low-grade charcoal (an industrial by-product), Alum-based Adsorbent (ABA), and Zeolite, a natural substance. These effectively removed the main leachate contaminants: low-grade charcoal for antibiotics (initial concentration 1.05 mg/L, removal rate 73.4%), ABA for phosphate (initial concentration 2.53 mg/L, removal rate 99.9%), and zeolite for ammonium (initial concentration 38.92 mg/L, removal rate 100.0%). The optimal mix ratio for purifying leachate is 1:1:10 of low-grade charcoal, ABA, and zeolite. The average adsorbent usage per burial site was 1,800 kg, costing KRW 2,000,000 per ton. The cost for the minimum leachate volume (about 12.4 m³) per site is KRW 2,880,000, and for the maximum volume (about 19.7 m³) is KRW 4,620,000. These findings contribute to resolving issues related to livestock carcass burial sites and suggest post-management strategies by advocating for the effective use of adsorbents in leachate purification.

• 한국광물학회지
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• 제17권3호
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• pp.235-243
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• 2004

일라이트는 닳은 모서리(frayed edge)의 존재에 의하여 다른 알칼리 금속과 비교할 때 낮은 농도에서 선택적으로 Cs을 더 잘 흡수하는 것으로 알려져 있다. 이 닳은 모서리는 기존의 일반적인 흡착실헐에 의하여 존재한다고 알려져 있지만 다른 분석방법으로는 증명되지 않은 상태이다. 일라이트 표면에서의 Cs의 흡착특성을 알아보기 위하여 닳은 모서리를 증가시킨 인위적으로 풍화된 일라이트와 Cs을 여곤 농도에서 반응을 시켰다. 일라이트는 0.001 M의 HC1 용액에서 1시간, 2일, 14일 동안 반응시켜 K 이온의 방출 및 XRD, SEM, TEM 등으로 풍화상태를 확인하였다. 풍화되지 않은 일라이트와 풍화된 일라이트를 Na-일라이트로 교환한 후 $10^{-3}$ ～ $10^{-7}$ M 농도의 CsCl 용액에서 24시간 반응시켰다. Cs의 흡착특성은 $10^{ -5}$M Cs 용액농도를 기준으로 뚜렷한 차이를 보이다. 일라이트에 흡착된 Cs은 낮은 Cs 농도 (<$10^{-5}$ M )에서 높은 Cs 농도보다 상대적으로 많은 Cs이 흡착되었으며 이러한 상대적 흡착 농도는 용액의 농도가 낮아질수록 높아진다. 일반적으로 흡착된 Cs는 풍과가 오래된 시료일수록 낯은 농도에서 뚜렷하나 높은 농도에서는 그 차이가 적다. 이러한 결과는 낮은 농도에서 닳은 모서리라고 불리는 흡착자리의 존재에 의한 것이고 이러한 자리는 풍화가 진행됨에 따라서 증가된다.

• 한국광물학회지
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• 제17권2호
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• pp.157-168
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• 2004

수용액 내 캐올리나이트와 할로이사이트의 표면화학 특성을 전위차 적정 실험과 FITEQL3.2 프로그램을 이용하여 연구하였다. 표면복합반응 모델 중 일정용량 모델을 적용하였으며, 표면을 사면체 자리와 팔면체 자리로 나누어 설정한 2 sites - 3 $pK_{a/s}$ 모델은 캐올리나이트와 할로이사이트의 표면화학 특성을 설명하는데 적합하였다. 두 점토광물 표면은 pH 4 이상에서 음전하를 띄며 pH가 높아질수록 양성자 표면 전하 밀도는 낮아진다. 산성 및 중성 영역에선 Si 사리(≡$SiO^{-}$ )가, 염기성 영역에선 Al 자리(≡$AlO^{-}$)가 양이온을 흡착하는데 중요한 역할을 할 것으로 예상된다. 모델링 결과 캐올리나이트의 경우 $pK_{a2(si)}$ /$^{int}$, p $K_{al(Al) }$ /$^{int}$ /, $pK_{a2}$ $(Al)^{int}$ /는 각각 4.436. 4.564, 및 8.461이며, 할로이사이트의 경우는 각각 7.852, 3.885, 7.084이다. 캐올리나이트의 총 Si 표면자리 농도와 총 Al 표면자리 농도는 0.215와 0.148 mM이며, 할로이사이트의 경우는 0.357과 0.246 mM이다 두 광물 모두 Si 표면자리 밀도 : Al 표면자리 밀도가 1 : 0.69로 비슷하다. 캐올리나이트의 총 표면자리 밀도는 3.774 sites/$nm^2$로 할로이사이트의 2.292 sites/n $m^2$ 값보다 약 1.6배정도 높다.다.

• Advances in environmental research
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• 제2권3호
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• pp.167-177
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• 2013

We investigated that removal of aqueous U(VI) by nano-sized Zero Valent Iron (nZVI) and Fe(II) bearing minerals (controls) in this study. Iron particles showed different U(VI) removal efficiencies (Mackinawite: 99%, green rust: 95%, nZVI: 91%, magnetite: 87%, pyrite: 59%) due to their different PZC (Point of Zero Charge) values and surface areas. In addition, noticeable amount of surface Fe(II) (181 ${\mu}M$) was released from nZVI suspension in 6 h and it increased to 384 ${\mu}M$ in the presence of U(VI) due to ion-exchange of U(VI) with Fe(II) on nZVI surface. Analysis of Laser-Induced Breakdown Detection (LIBD) showed that breakdown probabilities in both filtrates by 20 and 200 nm sizes was almost 24% in nZVI suspension with U(VI), while 1% of the probabilities were observed in nZVI suspension without U(VI). It indicated that Fe(II) colloids in the range under 20 nm were generated during the interaction of U(VI) and nZVI. Our results suggest that Fe(II) colloids generated via ion-exchange process should be carefully concerned during long-term remediation site contaminated by U(VI) because U could be transported to remote area through the adsorption on Fe(II) colloids.

• Carbon letters
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• 제12권3호
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• pp.167-170
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• 2011

Petroleum pitch-based activated carbons (ACs) were obtained in this work from a combination of pretreatment with different amounts of potassium permanganate ($KMnO_4$) and chemical activation with potassium hydroxide. The surface characteristics of the pitch after the $KMnO_4$ pretreatment were characterized by means of Fourier transform infrared spectroscopy (FT-IR). The structural characteristics of the pitch after the $KMnO_4$ pretreatment were determined by means of X-ray diffraction. The influence of the $KMnO_4$ treatment on the textural properties of the petroleum pitch-based ACs was investigated by means of $N_2$/77K adsorption isotherms. The investigation also involved the use of the Brunauer-Emmett-Teller equation and the Dubinin-Radushkevich method. The FT-IR results show that the pretreatment promotes the formation of surface oxygen functionalities and leads to an increase of the interplanar distance ($d_{002}$) of the functional groups induced between carbon layers. Moreover, the specific surface area of the pitch-based ACs increases in proportion to the amount of $KMnO_4$ pretreatment and reaches its highest value of 2334 $m^2$/g with 2 g of $KMnO_4$ because the surface oxygen groups of the pitch act as an active site during chemical activation.

• 한국미생물·생명공학회지
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• 제21권4호
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• pp.293-298
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• 1993

The ppage resistance mechanism of Lactococcus lactis subsp. cremoris ATCC 11602-A1 was investigated. When parent and A1 were incubated at 30 and 40$^{\circ}C$, A1 grew well and multiplication of phage(MOI=1)on A1 slightly occurred at 40$^{\circ}C$ in contrast with parent. There was a great difference of proteolytic activity between parent and A1, irrespective of the temperature. As a result of ADS treatment oon culture broth, survival rate of A1 was 27% at the lethal concentration of parent and adsorption rate of phage was increased to 95~97%, which was considered to come from the exposure of phage receptor site masked by an unknown component. These results suggest that acridine orange (AO) treatment leads to the modification of cell wall, conferring resistance to high temperature and lytic phage. No change in plasmid profiles of A1 at 30 and 40$^{\circ}C$ were found, which suggests that plasmid is not relative to temperature-resistance of A1.

• 한국미생물·생명공학회지
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• 제24권6호
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• pp.678-686
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• 1996

To improve the preservation of Kimchi, we isolated Lactobacillus plantarum lytic enzyme-producing strain from soil, and the enzyme was purified and characterized. From the observation of cultural and morpho- logical characteristics, the isolated strain was identified as Metarrisium anisopliae (Metschn.) Sorok. The enzyme was purified to 75-folds with 40% yields through affinity adsorption and CM-Sephadex C-50 column chromatog- raphy. The optimum pH and temperature for lytic activity are 4.0 and 40$\circ$C, respectively, and the enzyme acitvity is stable between pH 3.0 and 9.0, and up to 50$\circ$C. The enzyme is a monomeric protein with molecular weight of 40,000 daltons by SDS-PAGE and gel filtration. The enzyme is endopeptidase which breaks the peptide linkage of Lactobacillus plantarum peptidoglycan. The lytic action spectra confirmed that Leuconostoc mesenteroides, a useful strain for the fermentation of Kimchi, is not lysed by the enzyme. The enzyme activity is inhibited by N-bromosuccinimide (NBS), which probably indicates the involvement of tryptophan residue in active site of the enzyme, and also inhibited by Ag$^{+}$. The amino acid composition analysis showed that the enzyme contains more acidic amino acids than basic ones, and composition of alanine, glycine, proline and tyrosines was very high.