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Oxidation of ash-free coal from sub-bituminous and bituminous coals in a direct carbon fuel cell
Choong-Gon Lee,Duc-Luong Vu 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.2
The present study proposes the production of ash-free coal (AFC) and its oxidation as a primary fuel in direct carbon fuel cells (DCFCs). The AFC was produced by the extraction of Arutmin sub-bituminous coal (AFC1) and Berau bituminous coal (AFC2) using polar solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). It was carried out at a temperature of around 202 oC under atmospheric conditions and using a microwave irradiation method. Using NMP as the solvent showed the highest extraction yield, and the values of 23.53% for Arutmin coal and 33.80% for Berau coal were obtained. When NMP was added to DMSO, DMA and DMF, the extraction yield in the solvents was greatly increased. The yield of AFC from a sub-bituminous coal was slightly lower than that from a bituminous coal. The AFC was evaluated in a coin-type DCFC with a mixture of AFC and carbonate electrolyte (3 g/3 g) at 850 oC. The AFC and gaseous H2 fuels were compared using the electrochemical methods of steady-state polarisation and step chronopotentiometry. The DCFC ran successfully with the AFCs at 850 oC. The open-circuit voltages were about 1.35 V (AFC1) and 1.27 V (AFC2), and the voltages at 150 mA cm−2 were 0.61 V (AFC1) and 0.74 V (AFC2).
Characteristics of Solid Fuel Oxidation in a Molten Carbonate Fuel Cell
Lee, Choong-Gon,Kim, Yu-Jeong,Kim, Tae-Kyun,Lee, Sang-Woo The Korean Electrochemical Society 2016 Journal of electrochemical science and technology Vol.7 No.2
Oxidation behaviours of ash free coal (AFC), carbon, and H<sub>2</sub> fuels were investigated with a coin type molten carbonate fuel cell. Because AFC has no electrical conductivity, its oxidation occurs via gasification to H<sub>2</sub> and CO. An interesting behaviour of mass transfer resistance reduction at higher current density was observed. Since the anode reaction has the positive reaction order of H<sub>2</sub>, CO<sub>2</sub> and H<sub>2</sub>O, the lack of CO<sub>2</sub> and H<sub>2</sub>O from AFC results in a significant mass transfer resistance. However, the anode products of CO<sub>2</sub> and H<sub>2</sub>O at higher current densities raise their partial pressure and mitigate the resistance. The addition of CO<sub>2</sub> to AFC reduced the resistance sufficiently, thus the resistance reduction at higher current densities did not appear. Electrochemical impedance results also indicate that the addition of CO<sub>2</sub> reduces mass transfer resistance. Carbon and H<sub>2</sub> fuels without CO<sub>2</sub> and H<sub>2</sub>O also show similar behaviour to AFC: mass transfer resistance is diminished by raising current density and adding CO<sub>2</sub>.
Lee, Dong-Hoon,Lee, Do-Wan,Kwon, Jae-Im,Kim, Sang-Tae,Woo, Chul-Woong,Kon Kim, Jeong,Won Kim, Kyung,Seong Lee, Jin,Gon Choi, Choong,Suh, Ji-Yeon,Choi, Yoonseok,Woo, Dong-Cheol Elsevier 2019 Brain Research Vol.1717 No.-
<P><B>Abstract</B></P> <P><B>Purpose</B></P> <P>To evaluate temporal changes in gamma-aminobutyric acid (GABA) signals in the hippocampus during epileptiform activity induced by kainic acid (KA) in a rat model of status epilepticus using chemical exchange saturation transfer (CEST) imaging technique.</P> <P><B>Methods</B></P> <P>CEST imaging and <SUP>1</SUP>H magnetic resonance spectroscopy (<SUP>1</SUP>H MRS) were applied to a systemic KA-induced rat model to compare GABA signals. All data acquisition and analytical procedures were performed at three different time points (before KA injection, and 1 and 3 h after injection). The CEST signal was analyzed based on regions of interests (ROIs) in the hippocampus, while <SUP>1</SUP>H MRS was analyzed within a 12.0 μL ROI in the left hippocampus. Signal correlations between the two methods were evaluated as a function of time change up to 3 h after KA injection.</P> <P><B>Results</B></P> <P>The measured GABA CEST-weighted signal intensities of the rat epileptic hippocampus before injection showed significant differences from those after (averaged signals from both hippocampi: 4.37% ± 0.87% and 7.305 ± 1.11%; P < 0.05), although the signal had increased slightly at both time points after KA injection, the differences were not significant (P > 0.05). In contrast, the correlation between the CEST imaging values and <SUP>1</SUP>H MRS was significant (r ≥ 0.64; P < 0.05; in all cases).</P> <P><B>Conclusions</B></P> <P>GABA signal changes during epileptiform activity in the rat hippocampus, as detected using CEST imaging, provided a significant contrast according to changes in metabolic activity. Our technical approach may serve as a potential supplemental option to provide biomarkers for brain disease.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We evaluated the feasibility of CEST imaging for GABA detection in the rat models of status epilepticus. </LI> <LI> GABACEST-weighted signals were compared to GABA concentrations acquired from <SUP>1</SUP>H MRS. </LI> <LI> GABACEST-weighted signals showed significant differences between pre- and post-epileptic status. </LI> </UL> </P>
Choong-Min Lee,Pureum Kang,Chang-Keun Cho,Hye-Jung Park,Yun Jeong Lee,Jung-Woo Bae,Chang-Ik Choi,Hyung Sik Kim,Choon-Gon Jang,Seok-Yong Lee 대한약학회 2022 Archives of Pharmacal Research Vol.45 No.6
Metoprolol, a selective β 1 -adrenoreceptor blockingagent used in the treatment of hypertension, angina,and heart failure, is primarily metabolized by the CYP2D6enzyme, which catalyzes α-hydroxylation and O-desmethylation. As CYP2D6 is genetically highly polymorphic andthe enzymatic activity diff ers greatly depending on the presenceof the mutant allele(s), the pharmacokinetic profi le ofmetoprolol is highly variable depending on the genotype ofCYP2D6 . The aim of study was to develop the physiologicallybased pharmacokinetic (PBPK) model of metoprololrelated to CYP2D6 genetic polymorphism for personalizedtherapy with metoprolol. For PBPK modelling, our previouspharmacogenomic data were used. To obtain kinetic parameters(K m , V max , and CL int ) of each genotype, the recombinantCYP enzyme of each genotype was incubated with metoprololand metabolic rates were assayed. Based on these data,the PBPK model of metoprolol was developed and validatedin diff erent CYP2D6 genotypes using PK-Sim ® software. As a result, the input values for various parameters for the PBPK model were presented and the PBPK model successfullydescribed the pharmacokinetics of metoprolol ineach genotype group. The simulated values were within theacceptance criterion (99.998% confi dence intervals) comparedwith observed values. The PBPK model developedin this study can be used for personalized pharmacotherapywith metoprolol in individuals of various races, ages, andCYP2D6 genotypes.
Analysis of Flow Rate Inducing Voltage Loss in a 100 cm<sup>2</sup> Class Molten Carbonate Fuel Cell
Lee, Choong-Gon The Korean Electrochemical Society 2011 Journal of electrochemical science and technology Vol.2 No.1
This work focuses on the behavior of the overpotential increase due to a utilization rise in a molten carbonate fuel cell. The behavior is generally explained by Nernst loss, which is a kind of voltage loss due to the thermodynamic potential gradients in a polarization state due to the concentration distribution of reactant species through the gas flow direction. The evaluation of Nernst loss is carried out with a traditional experimental method of constant gas utilization (CU). On the other hand, overpotential due to the gas-phase mass-transport resistance at the anode and cathode shows dependence on the utilization, which can be measured using the inert gas step addition (ISA) method. Since the Nernst loss is assumed to be due to the thermodynamic reasons, the voltage loss can be calculated by the Nernst equation, referred to as a simple calculation (SC) in this work. The three values of voltage loss due to CU, ISA, and SC are compared, showing that these values rise with increases in the utilization within acceptable deviations. When we consider that the anode and cathode reactions are significantly affected by the gas-phase mass transfer, the behavior strongly implies that the voltage loss is attributable not to thermodynamic reasons, namely Nernst loss, but to the kinetic reason of mass-transfer resistance in the gas phase.