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Jo, S.H.,Park, C.,Yi, S.C.,Kim, D.,Mun, S. Elsevier 2011 Journal of Chromatography A Vol.1218 No.33
A three-zone carousel process, in which Cu(II)-imprinted polymer (Cu-MIP) and a buffer solution were employed as adsorbent and eluent respectively, has been developed previously for continuous separation of Cu<SUP>2+</SUP> (product) from Mn<SUP>2+</SUP> and Co<SUP>2+</SUP> (impurities). Although this process was reported to be successful in the aforementioned separation task, the way of using a buffer solution as eluent made it inevitable that the product stream included the buffer-related metal ions (i.e., the constituent metal ions of the buffer solution) as well as copper ions. For a more perfect recovery of copper ions, it would be necessary to improve the previous carousel process such that it can remove the buffer-related metal ions from copper ions while maintaining the previous function of separating copper ions from the other 2 impure heavy-metal ions. This improvement was made in this study by proposing a four-zone carousel process based on the following strategy: (1) the addition of one more zone for performing the two-step re-equilibration tasks and (2) the use of water as the eluent of the washing step in the separation zone. The operating conditions of such a proposed process were determined on the basis of the data from a series of single-column experiments. Under the determined operating conditions, 3 runs of carousel experiments were carried out. The results of these experiments revealed that the feed-loading time was a key parameter affecting the performance of the proposed process. Consequently, the continuous separation of copper ions from both the impure heavy-metal ions and the buffer-related metal ions could be achieved with a purity of 91.9% and a yield of 92.8% by using the proposed carousel process based on a properly chosen feed-loading time.
Clomipramine block of the hERG K<sup>+</sup> channel: Accessibility to F656 and Y652
Jo, S.H.,Hong, H.K.,Chong, S.H.,Won, K.H.,Jung, S.J.,Choe, H. North-Holland ; Elsevier Science Ltd 2008 european journal of pharmacology Vol.592 No.1
Clomipramine is a tricyclic antidepressant for psychiatric disorders that can induce QT prolongation, which may lead to torsades de pointes. Since blockade of cardiac human ether-a-go-go-related gene (hERG) channels is an important cause of acquired long QT syndrome, we investigated the acute effects of clomipramine on hERG channels to determine the electrophysiological basis for its proarrhythmic potential. We examined the effects of clomipramine on the hERG channels expressed in Xenopus oocytes and HEK293 cells using two-microelectrode voltage-clamp and patch-clamp techniques. Clomipramine induced a concentration-dependent decrease in the current amplitude at the end of the voltage steps and hERG tail currents. The IC50 for clomipramine needed to block the hERG current in Xenopus oocytes decreased progressively relative to the degree of depolarization. The fractional electrical distance was estimated to be δ=0.83. The IC50 for the clomipramine-induced blockade of the hERG currents in HEK293 cells at 36 <SUP>o</SUP>C was 0.13 μM at +20 mV. Clomipramine affected the channels in the activated and inactivated states but not in the closed states. The clomipramine-induced blockade of hERG was found to be use-dependent, exhibiting a more rapid onset and a greater steady-state block at the higher frequencies of activation. The S6 domain mutations, Y652A and F656A partially attenuated (Y652A) or abolished (F656A) the hERG-current blockade. These results suggest that clomipramine is a blocker of the hERG channels, providing a molecular mechanism for the arrhythmogenic side effects during the clinical administration of clomipramine.
Jo, S.H.,Kim, K.H.,Jeon, B.H.,Lee, M.H.,Kim, Y.H.,Kim, B.W.,Cho, S.B.,Hwang, O.H.,Bhattacharya, S.S. Pergamon Press ; Elsevier [distribution] 2015 Atmospheric environment Vol.119 No.-
In this study, emission characteristics of major odorants in pig confinement facilities were investigated through comparative analysis between odorant composition and odor intensity. Odorant samples in ambient air were collected from five different paired sampling sites: (1) in- and outside of windowless pig barn, (2) in- and outside of open pig barn, (3) before/after slurry treatment (via liquid fertilization), (4) before/after composting, and (5) two reference background sites on a pig confinement facility. A total of 47 compounds consisting of key offensive odorants (such as reduced sulfur and volatile organic compounds) were measured from each selected site. When the results are compared in terms of odor intensity, a list of odorants (sulfur compounds, volatile fatty acids, phenols, and indoles) were generally seen at enhanced levels on most sites. In two types of pig barn facilities (windowless ('W') and open ('O')), butyric and valeric acid were the predominant species. The removal efficiency of odorants was quite different between the two slurry treatment approaches of composting and liquid fertilization. Although the efficiencies of odor removal in the former were not sufficient, that of the latter was fairly significant in terms of odor intensity. However, some odorants like hydrogen sulfide, methanethiol, p-cresol, and butyric acid were still retained above the odor threshold level. Accordingly, odorant emissions from animal housing facilities can be characterized most effectively by key odorants such as volatile fatty acids and reduced sulfur species.
Jo, S.H.,Kim, K.H. Elsevier 2016 Journal of chromatography Vol.1429 No.-
<P>In this study, an experimental method for the collection and analysis of carbonyl compounds (CCs) released due to the use of electronic cigarettes (e-cigarettes or ECs) was developed and validated through a series of laboratory experiments. As part of this work, the conversion of CCs from a refill solution (e-solution) to aerosol also was investigated based on mass change tracking (MCT) approach. Aerosol samples generated from an e-cigarette were collected manually using 2,4-dinitrophenylhydrazine (DNPH) cartridges at a constant sampling (puffing) velocity of 1 L min(-1) with the following puff conditions: puff duration (2 s), interpuff interval (10 s), and puff number (5,10, and 15 times). The MCT approach allowed us to improve the sampling of CCs through critical evaluation of the puff conditions in relation to the consumed quantities of refill solution. The emission concentrations of CCs remained constant when e-cigarettes were sampled at or above 10 puff. Upon aerosolization, the concentrations of formaldehyde and acetaldehyde increased 6.23- and 58.4-fold, respectively, relative to their concentrations in e-solution. Furthermore, a number of CCs were found to be present in the aerosol samples which were not detected in the initial e-solution (e.g., acetone, butyraldehyde, and o-tolualdehyde). (C) 2015 Elsevier B.V. All rights reserved.</P>
Jo, S.H.,Kim, K.H.,Kim, Y.H. Elsevier Pub. Co 2016 Analytica chimica acta Vol.944 No.-
In this study, a novel quantitation method was developed to facilitate the simple and effective sampling and analysis of phthalates in air based on a sorbent tube-thermal desorption-gas chromatography-mass spectrometry system combination. The performance of the thermal desorption-based analysis was assessed using three different sorbent combinations [1]: quartz wool (QW) [2], glass wool (GW), and [3] quartz wool plus Tenax TA (QWTN) in terms of relative recovery in reference to a direct injection method. There was no significant difference in the average recovery rate for seven target phthalates based on sorbent tube type (QW, 70.2 +/- 4.28; GW, 73.2 +/- 8.8; and QWTN, 72.5 +/- 5.02%). However, the recovery rate of phthalates in each sorbent tube type was distingusihed by physicochemical properties of the target compound (e.g., molecular weight and boiling point). The recovery rate of the QW tube was high for dimethyl phthalate and diethyl phthalate compared to other sorbent tubes, while that of the GW tube exhibited greater values for dibutyl phthalate, benzyl butyl phthalate, di(2-ethylhexyl) adipate, di(2-ethylhexyl) phthalate, and di-n-octyl phthalate. The simple sorbent tube-thermal desorption approach is feasible for the quantitation of seven phthalates present at 0.45-24.5 ng m<SUP>-3</SUP> levels in actual air samples (20 L).
Application of Microbial Calcite to Fiber Reinforced Soils to Reduce Wind Erosion Potential
Josh Ander Son,Sookie S Bang,Sang Chul Bang,Seok J Lee,Nam Y Dho,Seong R Choi,Sung Hwan Ko 한국지반공학회 2012 international journal of geo-engineering Vol.4 No.2
Airborne dust and sand particles caused by wind erosion have been associated with serious problems in human health as well as high tech industrial machines. In particular, sand particles originated from Mongolia and northern China due to increasing desertification have been the main cause of frequent such problems in Far East Asia. In the past, the majority of control methods have been either chemical or mechanical, resulting in certain degrees of health hazard or frequent applications. An alternative method, surface vegetation, becomes increasingly popular but it is very slow and costly. Recently, the authors have introduced a biological technique utilizing a naturally occurring microorganism, Sporosarcina pasteurii. This soil microorganism is ureolytic, expressing the urease enzyme that hydrolyzes urea to ammonium and carbonate ions. The ammonium ions raise the surrounding pH, in turn promoting calcium carbonate (calcite) precipitation in the presence of calcium ions. This precipitate has shown great dust suppression potential. The main objective of this study is to examine the application of microbial calcite with soil fibers to reduce the wind erosion potential, using S. pasteurii mixed with medium containing urea and calcium chloride in order to develop an environmentally safe and economically feasible technique to minimize the spread of desertification.