• Title/Summary/Keyword: chemical shift

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Multiscale Modeling and Simulation of Water Gas Shift Reactor (Water Gas Shift Reactor의 Multiscale 모델링 및 모사)

  • Lee, Ukjune;Kim, Kihyun;Oh, Min
    • Korean Chemical Engineering Research
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    • v.45 no.6
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    • pp.582-590
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    • 2007
  • In view of the analysis of the phenomena and the prediction of the performance, mathematical modelling and simulation of a high temperature pilot reactor for water gas shift reaction (WGSR) has been carried out. Multiscale simulation incorporated computational fluid dynamics (CFD) technique, which has the capability to deal with the reactor shape, fluid and energy transport with extensive degree of accuracy, and process modeling technique, which, in turn is responsible for reaction kinetics and mass transport. This research employed multiscale simulation and the results were compared with those from process simulation. From multiscale simulation, the maximum conversion of was predicted approximately 0.85 and the maximum temperature at the reactor was calculated 720 K, resulting from the heat of reaction. Dynamic simulation was also performed for the time transient profile of temperature, conversion, etc. Considering the results, it is concluded that multiscale simulation is a safe and accurate technique to predict reactor behaviors, and consequently will be available for the design of commercial size chemical reactors as well as other commercial unit operations.

Phosphorylation-Dependent Mobility Shift of Proteins on SDS-PAGE is Due to Decreased Binding of SDS

  • Lee, Chang-Ro;Park, Young-Ha;Kim, Yeon-Ran;Peterkofsky, Alan;Seok, Yeong-Jae
    • Bulletin of the Korean Chemical Society
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    • v.34 no.7
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    • pp.2063-2066
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    • 2013
  • While many eukaryotic and some prokaryotic proteins show a phosphorylation-dependent mobility shift (PDMS) on SDS-PAGE, the molecular mechanism for this phenomenon had not been elucidated. We have recently shown that the distribution of negatively charged amino acids around the phosphorylation site is important for the PDMS of some proteins. Here, we show that replacement of the phosphorylation site with a negatively charged amino acid results in a similar degree of the mobility shift of a protein as phosphorylation, indicating that the PDMS is due to the introduction of a negative charge by phosphorylation. Compared with a protein showing no shift, one showing a retarded mobility on SDS-PAGE had a decreased capacity for SDS binding. The elucidation of the consensus sequence (${\Theta}X_{1-3}{\Theta}X_{1-3}{\Theta}$, where ${\Theta}$ corresponds to an acidic function) for a PDMS suggests a general strategy for mutagenizing a phosphorylatable protein resulting in a PDMS.

CHEMICAL SHIFT IMAGING

  • Yi, Yun;Kim, Min-Gi
    • Proceedings of the KOSOMBE Conference
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    • v.1992 no.11
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    • pp.22-25
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    • 1992
  • Lipid component and water component image in living organism can be acquired due to its chemical shift difference. Various techniques for chemical shift imaging were used for acquiring separated image. It is necessary two imaging experiments to acquire two separated images wi th Dixon's method. This technique is less susceptible to local magnetic inhomogeneities and easily applied to multi-slice imaging. With CHESS and SECSI method, which based on chemical selectivity of R.F pusle, either water or lipid image can be acquired by one imaging experiment. However, those are more susceptible to local magnetic field inhomogeneities and difficult to apply to multi-slice imaging. The SECSI method showed best signal suppression ratio of fat and water, which is measure of separation of water and fat.

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Backbone NMR chemical shift assignment for the substrate binding domain of Escherichia coli HscA

  • Jin Hae Kim
    • Journal of the Korean Magnetic Resonance Society
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    • v.28 no.2
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    • pp.6-9
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    • 2024
  • HscA is a Hsp70-type chaperone protein that plays an essential role to mediate the iron-sulfur (Fe-S) cluster biogenesis mechanism in Escherichia coli. Like other Hsp70 chaperones, HscA is composed of two domains: the nucleotide binding domain (NBD), which can hydrolyze ATP and use its chemical energy to facilitate the Fe-S cluster transfer process, and the substrate binding domain (SBD), which directly interacts with the substrate, IscU, the scaffold protein of an Fe-S cluster. In the present work, we prepared the isolated SBD construct of HscA (HscA(SBD)) and conducted the solution-state nuclear magnetic resonance (NMR) experiments to have its backbone chemical shift assignment information. Due to low spectral quality of HscA(SBD), we obtained all the NMR data from the sample containing the peptide LPPVKIHC, the HscA-interaction motif of IscU, from which the chemical shift assignment could be done successfully. We expect that this information provides an important basis to execute detailed structural characterization of HscA and appreciate its interaction with IscU.

Problems of Working Hours and Shift Work Systems, and Propsed Methods for Their Improvement (근로시간 및 교대근무편성의 문제점과 개선방향)

  • Seo, Yu-Jin;;Park, Yeong-Man;Mun, Se-Geun
    • Journal of the Ergonomics Society of Korea
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    • v.22 no.3
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    • pp.13-26
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    • 2003
  • The purpose of this study is to investigate the present conditions of the night work and shift work systems in the heavy chemical industrial complexes found in Changwon, Masan, and Chinhae. Korea. We will attempt to define and classify their problems; and to discover further ways to improve their systems. Fifty production factories were carefully selected as the subjects for this study. The shift systems were classified into five categories. The consecutive night shifts were long in almost all cases with 6 days (36 factories) and 7 days (13 factories). It was found that the night work of about] 2 hours continues for a long period in the weekly rotation full-day shift systems and the night-including non-full-day shift systems, and there was no holiday during a shift cycle in the continuous full-day shift systems. The work time in most shift systems was longer than the 44-hours/week permitted by Korean law. Considering the characteristics of these various types of shift systems, the most essential thing to reduce the shift workers' work load may be to shorten their working hours and improve the schedule of shift systems. It is highly recommended as a fundamental solution. to reduce the portal-to-portal hours from 12 to 8 in the night-including non-full-day shift systems and the weekly rotation full-day shift systems, and at least to employ a 4-team 3-shift system in the continuous full-day shift systems. In addition to this, it should from now on be taken as a goal to restructure the types of shift systems by taking such measures as avoiding continuous night work if possible, providing sufficient off-duty intervals both before and after night shift, providing increased opportunities for workers to nap during night work. and increasing the number of holidays.

A Study on the Reduction of the Magnetic Susceptibility Artifact in MRI of the Cervical Spine with Chemical Shift Selective Fat Suppression (CHESS 기법을 이용한 지방소거 경추 자기공명영상에서 자화감수성 인공물을 줄이기 위한 연구)

  • Lim, Woo-Taek;Jeong, Hong-Ryang
    • Proceedings of the Korea Contents Association Conference
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    • 2014.11a
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    • pp.197-198
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    • 2014
  • CHESS(chemical shift selective saturation) 기법을 이용한 경추 자기공명영상에서 주로 나타나는 자화 감수성 인공물(susceptibility artifact)을 줄이기 위한 보조물질을 찾고자 하였다.

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