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Han, Sang-Beom,Kwak, Da-Hee,Park, Hyun Suk,Park, Jin-Young,Ma, Kyeng-Bae,Won, Ji-Eun,Kim, Do-Hyoung,Kim, Min-Cheol,Park, Kyung-Won Elsevier 2018 Journal of Power Sources Vol.393 No.-
<P><B>Abstract</B></P> <P>(2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) with no free radical and non-volatile characteristic can be utilized as a liquid catalyst instead of O<SUB>2</SUB> at the cathode in a chemical regenerative redox fuel cell with H<SUB>2</SUB> as a fuel at the anode. In this study, the electrochemical properties and performance of TEMPO dissolved in sulfuric acid solution are investigated using half and unit cells. In the half-cell, TEMPO shows an activation energy of 1.27 kcal mol<SUP>−1</SUP> K<SUP>−1</SUP> for the reduction. A chemical regenerative redox fuel cell (CRRFC) using TEMPO as the liquid catalyst exhibits an open circuit voltage of 0.7 V and a maximum power density of 90 mW cm<SUP>−2</SUP> at 30 °C with a low activation loss. The regeneration cycling test of the CRRFC is performed at a constant voltage of 0.4 V under a flow rate of the oxygen-bubbled TEMPO solution. The performance of the CRRFC deteriorates, i.e., a power density of zero measured at >200 min. Thus, a highly efficient regeneration system needs to be developed for a high-performance CRRFC using TEMPO used as a liquid-type oxidant. Furthermore, stable liquid oxidants with relatively high standard reduction potentials can be proposed through various organic compounds.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CRRFC was proposed using TEMPO instead of O<SUB>2</SUB> at the cathode. </LI> <LI> TEMPO showed fairly fast transport and low activation energy for the reduction. </LI> <LI> CRRFC exhibited an open circuit voltage of ∼0.7 V at 30 °C. </LI> <LI> CRRFC exhibited a maximum power density of ∼90 mW cm<SUP>−2</SUP> at 30 °C. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Solidification of Radioactively Contaminated Soils Using Cement Waste Forms
Hyun-min Ma,Byoungkwan Kim,Jaehyuk Kang,Seokyoung Oh,Younglim Shin,Wooyong Um 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
The soils contaminated with radionuclides such as Cs-137 and Sr-90 should be solidified using a binder matrix, because radioactively contaminated soils pose environmental concerns and human health problems. Ordinary Portland cement has been widely used to solidify various radioactive wastes due to its low cost and simple process. In this study, simulant soil waste was solidified using cement waste form. The soils were collected around ‘Kori Nuclear Power Plant Unit 1’ and they were contaminated with the prepared simulant liquid waste containing Fe, Cr, Cs, Ni, Co, and Mn. The water-to-dry ingredients (W/D) ratio of cement waste form was 0.40. The cement paste was poured into a cubic mold (5×5×5 cm) and then cured for 28 days at room temperature. The 28-day compressive strength, water immersion, and EPA1311-toxicity characteristic leaching procedure (TCLP) tests were performed to evaluate the structural stability of cement waste form. The compressive strength was not proportional to soil waste loading, and the lowest compressive strength (4±0.1 MPa) was achieved in cement waste form containing 50wt% soil waste. After the water immersion test for 90 days, the compressive strength of cement waste form with 50wt% soil waste increased to 7.5±0.6 MPa, meeting the waste form acceptance criteria in the repository. It is believed that long-term water immersion test contributed to the additional curing and hydration reaction, resulting in the enhanced compressive strength. As a result of the TCLP test, the released amount of As, Ba, Cd, Cr, Pb, Se, Co, Cs, and Sr was less than the domestic and international standards. These results imply that cement waste form can be a promising candidate for the solidification of radioactive soil wastes.
Park, Hyun-Suk,Han, Sang-Beom,Kwak, Da-Hee,Lee, Gyu-Ho,Choi, In-Ae,Kim, Do-Hyoung,Ma, Kyeng-Bae,Kim, Min-Cheol,Kwon, Hye-Jin,Park, Kyung-Won WILEY-VCH 2017 CHEM SUS CHEM Vol.10 No.10
<P>To develop doped carbon nanostructures as non-precious metal cathode catalysts, nanocomposites were synthesized by using SBA-15 and 5,10,15,20-tetrakis(4-methoxyphenyl)-porphyrin-iron(III) chloride with different ratios of amorphous MoS2 precursor. From various analyses, it was found that, during pyrolysis at 900 degrees C under an N-2 atmosphere, the amorphous MoS2 precursor decomposed into Mo and S, facilitating the formation of graphene sheet-like carbon with MoC and doping of sulfur in the carbon. In the nanocomposite formed from 10 wt% MoS2 precursor (denoted as Mo/S/PC-10), most of the MoS2 was decomposed, thus forming S-doped carbon, which was grown on the MoC phase without crystalline MoS2. Furthermore, Mo/S/PC-10 exhibited better performance in the oxygen reduction reaction (specific activity of 1.23 mA cm(-2) at 0.9 V and half-wave potential of 0.864 V) than a commercial Pt catalyst, owing to a heteroatom-doped carbon nanostructure with a fairly high specific surface area. In the polarization curve of the unit-cell performance measured at 80 degrees C under ambient pressure, Mo/S/PC-10 as a cathode catalyst exhibited an optimal power density of 314 mW cm(-2) and a current density of 280 mA cm(-2) at 0.6 V.</P>
Analysis of Phenolic Compounds in Sorghum, Foxtail Millet and Common Millet
Hyun-Seok Jeon,Ill-Min Chung,Kyung-Ho Ma,Eun-Hye Kim,Soo-Jung Yong,Joung-Kuk Ahn 韓國作物學會 2011 Korean journal of crop science Vol.56 No.4
The cereal grain crops have strong flexibility against adverse environment and they have various functional compounds. The objective of the present study was to screen phenolic compounds in sorghum [Sorghum bicolor (L.) Moench], foxtail millet (Setaria italica), common millet (Panicum miliaceum L.) by high performance liquid chromatography (HPLC) with photodiode array (PDA) detector. Sorghum contained the highest amount of phenolic compounds among three different crops (sorghum, foxtail millet, common millet). Especially Moktaksusu showed the highest amount of phenolic compounds concentrations and biggest regional differences. The comparison of average phenolic compounds in sorghums by regions showed order to Milyang (963.3~;~mug~cdotg-1 ), Yeongyang (923.1~;~mug~cdotg-1 ), Gijang (831.3~;~mug~cdotg-1 ) and Bonghwa (735.6~;~mug~cdotg-1 ). Among the sorghum cultivars, Moktaksusu (1407.9~;~mug~cdotg-1 ) had the highest concentration of phenolic compounds. The average phenolic compounds of foxtail millets showed similar amount among Milyang (319.0~;~mug~cdotg-1 ), Gijang (288.1~;~mug~cdotg-1 ) and Bonghwa (281.9~;~mug~cdotg-1 ) areas. The phenolic compounds of Yeongyang (246.6~;~mug~cdotg-1 ) slightly low and that showed similar concentrations among three different regions. The concentration of phenolic compounds in foxtail millets, Chungchajo (335.6~;~mug~cdotg-1 ) showed the highest concentrations. The average phenolic compounds of common millets showed the highest concentrations in Milyang (305.5~;~mug~cdotg-1 ), Bonghwa (262.0~;~mug~cdotg-1 ), Gijang (195.1~;~mug~cdotg-1 ), Yeongyang (237.2~;~mug~cdotg-1 ) in decreasing order. The concentration of phenolic compounds of common millets was the highest in the Norangchalgijang (337.0~;~mug~cdotg-1 ), Hwanggumgijang (250.0~;~mug~cdotg-1 ) was also relatively higher than others. The results of this study will provide basic information for breeding sorghums, foxtail millets and common millets with higher phenolic compound concentrations.
Torque Onset Angle of the Knee Extensor as a Predictor of Walking Related Balance in Stroke Patients
Ma Min Kyeong,Cho TaeHwan,Lee Joo Won,Moon Hyun Im 대한재활의학회 2023 Annals of Rehabilitation Medicine Vol.47 No.4
Objective: To investigate the relationship between the torque onset angle (TOA) of the isokinetic test for knee extensors in the paretic side and walking related balance in subacute stroke patients.Methods: We retrospectively reviewed patients with first-ever strokes who have had at least two isokinetic tests within 6 months of onset. 102 patients satisfied the inclusion criteria. The characteristics of walking related balance were measured with the Berg Balance Scale sub-score (sBBS), Timed Up and Go test (TUG), 10-m Walk Test (10MWT) and Functional Independence Measure sub-score (sFIM). The second isokinetic test values of the knee extensor such as peak torque, peak torque to weight ratio, hamstring/quadriceps ratio, TOA, torque stop angle, torque at 30 degrees, and peak torque asymmetry ratio between paretic and non-paretic limb were also taken into account. Pearson’s correlation, simple regression and multiple regression analysis were used to analyze the correlation between TOA and walking related balance.Results: TOA of the knee extensor of the paretic limb showed significant correlations with BBS, sBBS, TUG, 10MWT, and sFIM according to Pearson’s correlation analysis. TOA also had moderate to good correlations with walking related balance parameters in partial correlation analysis. In multiple regression analysis, TOA of the paretic knee extensor was significantly associated with walking related balance parameters.Conclusion: This study demonstrated that TOA of the paretic knee extensor is a predictable parameter of walking related balance. Moreover, we suggest that the ability to recruit muscle quickly is important in walking related balance.
Inhibitory Effect of Triterpenes from Crataegus pinatifida on HIV-I Protease
Min, Byung Sun,Jung, Hyun Ju,Lee, Jun Sung,Kim, Young Ho,Bok, Song Hae,Ma, Chao Mei,Nakamura, Norio,Hattori, Masao,Bae, KiHwan 충남대학교 약학대학 의약품개발연구소 1999 藥學論文集 Vol.15 No.-
The methanol extracts of the leaves of Crataegus pinnatifida showed potent inhibitory activities against HIV-1 protease at a concentration of 100㎍/ml. The subsequent fractionation and isolation of the extract gave two active compounds. Their structures were identified as uvaol(1) and ursolic acid (2) by spectral data. These active compounds inhibit HIV-1 protease with IC_50 values of 5.5 and 8.0μM, respectively.
Anti-Obesity Effect of Kimchi with Starter Cultures in 3T3-L1 Cells
Hyun In-Kyung,Hong Sung Wook,Ma Min-Ji,Chang Ji Yoon,Lee Seongsoo,Yun Ye-Rang 한국미생물·생명공학회 2024 Journal of microbiology and biotechnology Vol.34 No.1
Lactic acid bacteria (LAB) isolated from kimchi have various functions, including antioxidant, antiinflammation, and anti-obesity activities, and are therefore widely used in the food, pharmaceutical, and medical fields. To date, the health functionalities of LAB have been widely reported; however, those of kimchi fermented with LAB as a starter have rarely been reported. Therefore, research on the selection of LAB with anti-obesity activity and the health functionality of kimchi fermented with LAB is needed. In the present study, LAB with anti-obesity activity were initially selected by measuring the Oil-Red O intensity. Among the four LAB strains, anti-obesity activity was confirmed by measuring cell viability, lipid levels, and lipid accumulation. Then, starter kimchi (SK) was prepared by inoculating selected LABs, and its pH, total acidity, and salinity were compared with those of naturally fermented kimchi (NK). Lastly, anti-obesity activity was also investigated in 3T3- L1 cells. Selected LAB showed no cytotoxicity up to 107 CFU/ml, with Lactobacillus brevis JC7 and Leuconostoc mesenteroides KCKM0828 having higher inhibitory effects on TG, TC content and lipid accumulation. Most SKs showed fermentation properties similar to those of the NK. SKs showed no cytotoxicity at concentrations of up to 1,000 μg/ml. SKs showed strong inhibitory effects on TG content, lipid accumulation, and obesity-related gene and protein expressions. Taken together, the utilization of LAB as a starter could improve the health benefits of kimchi.