Corrosion Behavior of Hastelloy C-276 for Carbon-anode-based Oxide Reduction Applications

Jeon, Min Ku,Kim, Sung-Wook,Choi, Eun-Young Korean Radioactive Waste Society 2020 방사성폐기물학회지 Vol.18 No.3

The corrosion behavior of Hastelloy C-276 was investigated to identify its applicability for carbon-anode-based oxide reduction (OR), in which Cl₂ and O₂ are simultaneously evolved at the anode. Under a 30 mL·min^-1 Cl₂ + 170 mL·min^-1 Ar flow, the corrosion rate was less than 1 g·m^-2·h^-1 up to 500℃, whereas the rate increased exponentially from 500 to 700℃. The effects of the Cl₂-O₂ composition on the corrosion rate at flow rates of 30 mL·min^-1 Cl₂, 20 mL·min^-1 Cl₂ + 10 mL·min^-1 O₂, and 10 mL·min^-1 Cl₂ + 20 mL·min^-1 O₂ with a constant 170 mL·min^-1 Ar flow rate at 600℃ was analyzed. Based on the data from an 8 h reaction, the fastest corrosion rate was observed for the 20 mL·min^-1 Cl₂ + 10 mL·min^-1 O₂ case, followed by 30 mL·min^-1 Cl₂ and 10 mL·min^-1 Cl₂ + 20 mL·min^-1 O₂. The effects of the chlorine flow rate on the corrosion rate were negligible within the 5-30 mL·min^-1 range. A surface morphology analysis revealed the formation of vertical scratches in specimens that reacted under the Cl₂-O₂ mixed gas condition.

Corrosion Behavior of Inconel X-750 for Carbon Anode Oxide Reduction Application

Jeon, Min Ku,Kim, Sung-Wook,Lee, Sang-Kwon,Choi, Eun-Young Korean Radioactive Waste Society 2020 방사성폐기물학회지 Vol.18 No.3

The corrosion behavior of the Inconel X-750 alloy was investigated for its potential application under a Cl₂-O₂ mixed gas flow in an Ar atmosphere. The corrosion rate was found to be negligible at temperatures up to 400℃ under a flow rate of 30 mL·min^-1 Cl₂ + 170 mL·min^-1 Ar, whereas an exponential increase was observed in the corrosion rate at temperatures greater than 500℃. The suppression of the corrosion reaction due to the presence of O₂ was verified experimentally at flow rates of 30 mL·min^-1 Cl₂ (4.96 g·m^-2·h^-1), 20 mL·min^-1 Cl₂ + 10 mL·min^-1 O₂ (2.02 g·m^-2 ·h^-1), and 10 mL·min^-1 Cl₂ + 20 mL·min^-1 O₂ (1.34 g·m^-2·h^-1) under a constant Ar flow rate of 170 mL·min^-1 at 600℃ for 8 h. The surface morphology analysis results revealed that porous surfaces with tunnel-type holes were produced under the Cl₂-O₂ mixed-gas condition. Furthermore, the effects of the Cl₂ flow rate on the corrosion rate were investigated, indicating that its impact was negligible within the range of 5-30 mL·min^-1 Cl₂ at 600℃.

Ultrasonic Degradation of Endocrine Disrupting Compounds in Seawater and Brackish Water

So Young Park,Jong Sung Park,Ha Yoon Lee,Ji Yong Heo,Yeo Min Yoon,Kyung Ho Choi,Nam Guk Her 대한환경공학회 2011 Environmental Engineering Research Vol.16 No.3

In this study, a series of experiments was conducted on the relative degradation of commonly known endocrine-disrupting compounds such as bisphenol A (BPA) and 17α-ethinyl estradiol (Ee₂) in a single-component aqueous solution using 28 and 580 kHz ultrasonic reactors. The experiments were conducted with three different types of model water: deionized water (DI), synthetic brackish water (SBW), and synthetic seawater (SSW) at pH 4, 7.5, and 11 in the presence of inert glass beads and humic acids. Significantly higher sonochemical degradation (93-97% for BPA) occurred at 580 kHz than at 28 kHz (43-61% for BPA), regardless of water type. A slightly higher degradation was observed for Ee₂ compared to that of BPA. The degradation rate of BPA and Ee₂ in DI water, SBW, and SSW after 30 min of ultrasound irradiation at 580 kHz increased slightly with the increase in pH from 4 (0.073-0.091 min-1 for BPA and 0.081-0.094 min-1 for Ee₂) to 7.5 (0.087-0.114 min-1 for BPA and 0.092?0.124 min-1 for Ee₂). In contrast, significant degradation was observed at pH 11 (0.149-0.221 min-1 for BPA and 0.147-0.228 min-1 for Ee₂). For the given frequencies of 28 and 580 kHz, the degradation rate increased in the presence of glass beads (0.1 mm and 25 g) for both BPA and Ee₂: 0.018-0.107 min-1 without beads and 0.052-0.142 min-1 with beads for BPA; 0.021-0.111 min-1 without beads and 0.054-0.136 min-1 with beads for Ee₂. A slight increase in degradation of both BPA and Ee₂ was found as the concentration of dissolved organic carbon (DOC, humic acids) increased in both SBW and SSW: 0.107-0.115 min-1 in SBW and 0.087-0.101 min-1 in SSW for BPA; 0.111-0.111 min-1 in SWB and 0.092-0.105 min-1 in SSW for Ee₂. After 30 min of sonicating the humic acid solution, DOC removal varied depending on the water type: 27% (3 mg L-1) and 7% (10 mg L-1) in SBW and 7% (3 mg L-1) and 4% (10 mg L-1) in SSW.

Nanogenerators: Fully Rollable Transparent Nanogenerators Based on Graphene Electrodes (Adv. Mater. 19/2010)

Choi, Dukhyun,Choi, Min-Yeol,Choi, Won Mook,Shin, Hyeon-Jin,Park, Hyun-Kyu,Seo, Ju-Seok,Park, Jongbong,Yoon, Seon-Mi,Chae, Seung Jin,Lee, Young Hee,Kim, Sang-Woo,Choi, Jae-Young,Lee, Sang Yoon,Kim, Jo WILEY-VCH Verlag 2010 ADVANCED MATERIALS Vol.22 No.19

<B>Graphic Abstract</B> <P>The cover shows an image of fully rollable transparent nanogenerators synthesized using chemical vapor deposition grown large-scale graphene sheets as transparent electrodes and piezoelectric ZnO nanorod arrays. Sang-Woo Kim, Jae-Young Choi, and co-workers report on p. 2187 the electrical and structural stability of the nanogenerators, with excellent charge scavenging performance under external mechanical loads such as bending and rolling. This study shows that graphene-based nanogenerators are very promising for self-powered rollable transparent device applications. <img src='wiley_img_2010/09359648-2010-22-19-ADMA201090066-content.gif' alt='wiley_img_2010/09359648-2010-22-19-ADMA201090066-content'> </P>

갑상선 기능항진증 환자에서 인슐린감수성 및 인슐린분비능의 변화

최은진,강호철,이태희,정민영,이대호,장연진,박상선,조재현 대한내분비학회 1994 Endocrinology and metabolism Vol.9 No.2

The impairement of glucose metabolism is frequently associated in hyperthyroidism. The present study was performed to determine the effect of the thyroid hormone excess on insulin sensitivity and on insulin secretory function in vivo. Ten newly diagnosed hyperthyroid patients and fifteen healthy control subjects were subjected to frequently sampled intravenous glucose tolerance tests(FSIGT) after an overnight fast. Insulin sensitivity, represented by the insulin sensitivity index(S_1), was assessed by minimal model analysis of FSIGT data. Insulin secretion was measured by the total area under the insulin curve after glucose load. The results were as follows. 1) The K_G values, which represent glucose tolerance, were not different between the hyperthyroid patients and the normals(2.2+-0.3 vs. 2.5+-0.3%/min, p$gt;0.05). 2) S_1 was significantly decreased in the hyperthyroid patients in comparison to the normals(7.5+-1.4 vs. 2.6+-0.3X10^-4 min^-1/uU/ml, p$lt;0.05). 3) The basal insulin concentration was higher in the hyperthyroid patients than in the normals(8.3+-2.4 vs. 4.6+-0.4 uU/ml, p=0.07). In addition, the insulin secretory response to a glucose load was increased in the hyperthyroid patients as evidenced by the peak plasma insulin level(168.2+-30.4 vs. 89.2+-13.9 uU/ml, p$lt;0.05) and by the total area under the insulin curve(2641.1+-443.2 vs. 1696.7+-204.3 min uU/ml, p$lt;0.05). These results clearly demonstrated that insulin sensitivity was impaired in these newly diagnosed hyperthyroid patients. However, glucose tolerance was maintained by the increased insulin secretion (J Kor Soc Endocrinol 9:108-114, 1994).

Conditioned Media of ASC-17D Sertoli Cells Induce G1-Growth Arrest of DU145 Human Prostate Cancer Cells

Min, Bon Hong,Kang, Sang Wook,Lee, Kwang Ho,Choi, Sang Hyun,Kang, Hyeog,Chun, Boe Gwun The Korea Science and Technology Center 1998 BMB Reports Vol.31 No.5

We studied the effects of ASC-17D rat Sertoli cell-conditioned media (rSCCM) on the proliferation of the DU145 prostate cancer cells. rSCCM was prepared from ASC-17D cells cultured in DMEM/F-12 serum-free media at a nonpermissive temperature of 40℃, which is the condition for the high expression of clusterin. We found that rSCCM could inhibit the proliferation of DU145 cells by arresting the cell cycle in the G1 phase in a dose-dependent manner. This growth arresting activity was abolished by boiling rSCCM for 5 min. The G1 growth-inhibiting activity of rSCCM was also detected in other prostate-originated cancer cells examined (ie., LNCaP and PC-3) but not in other cells (ASC-17D, HepG2, SK-N-SH, and NIH3T3). Western blot analysis of partially purified growth inhibiting fractions with the clusterin antibody showed that the cytostatic factor in rSCCM was not clusterin. This cytostatic factor was semipurified by DEAE-Sepharose, ammonium sulfate precipitation, and Phenyl-Sepharose column chromatography, and was estimated to have a molecular weight of 88 kDa by Sephacryl S-300 gel filtration.

Rheology of Decamethylceclopentasiloxane (cyclomethicone) W/O Emulsion System

Choi, Min-Hyung,Jeong, So-Ra,Nam, Sang-In,Shim, Sang-Eun,Chang, Yoon-Ho The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.12

A highly dispersed W/O emulsion of silicone oil (cyclomethicone)/water system was prepared with a nonionic surfactant. The surface and interfacial tension between the oil and water were characterized in terms of the droplet size distribution and viscosity change of the emulsion. When the dispersed phase concentration was relatively high, the viscosity of the emulsion was rapidly increased and the droplet size of the emulsion was decreased. The rheological behavior of the emulsion system showed non-Newtonian and shear thinning phenomena depending upon the content of the dispersed phase. The droplet size of the emulsion was decreased with increasing surfactant content and water concentration. The relative viscosity of the emulsion was better predicted with the Choi-Schowalter model than with the Taylor model. The value of the complex modulus increased with increasing surfactant concentration. The linear viscoelastic region was expanded with a dispersed phase concentration. According to the change in the viscosity, the behavior was classified into three distinct regions: [I] linear viscoelastic, [II] partially viscoelastic, and [III] viscous. The creep/recovery behaviors in each region were characterized.

성인에서 기관내삽관을 위한 Pipecuronium 일회 정주 적정 용량

최영석,윤석민,임상호,이미경,박영철,류태간 대한마취과학회 1997 Korean Journal of Anesthesiology Vol.33 No.3

Background : Studies in animals suggest that pipecuronium dose not induce hemodynamic chan-ges related to histamine release or to an effect on the autonomic nervous system. Therefore the effects of bolus administration of large doses of pipecuronium, up to 0.20 mg/kg, on the intubation condition, onset and duration of neuromuscular blockade, heart rate and blood pressure were studied during fentanyl- nitrous oxide anesthesia. Method : Forty adults were randomly assigned to receive a bolus injection of either 0.05, 0.10, 0.15, 0.20 mg/kg of pipecuronium. Neuromuscular blockade was measured using mechanomyographic activity of the adductor pollicis muscle after supramaximal stimulation of the ulnar nerve. Four subgroups of 10 patients received pipecuronium doses of 0.05, 0.10, 0.15 and 0.20 mg/kg, respectively, as an intubating dose. Results : The times of onset and clinical duration(mean sem) after each dose were as follows: 0.05 mg/kg, 2.98 0.42 and 41.5 2.42 min; 0.10 mg/kg, 1.54 0.06 and 82.9 7.48 min; 0.15 mg/kg, 1.41 0.14 and 124.8 13.1 min; 0.20 mg/kg, 1.12 0.05 and 187.1 12.8 min. The intubation condition, time of onset and duration after doses of 0.05 mg/kg were significantly different from values after the higer doses. The duration was increased with dose-increments. No dose-related changes in heart rate or blood pressure were observed. Conclusion : The authors conclude that dose of 0.10 mg/kg and over has good intubation condition clinically and large bolus dose of pipecuronium can be safely used with a significantly prolonged duration of action without hemodynamic change. (Korean J Anesthesiol 1997; 33: 453∼457)

Surface Modification of Block Copolymer Through Sulfur Containing Plasma Treatment

Choi, Sang Wook,Shin, Jae Hee,Jeon, Min Hwan,Mun, Jeong Ho,Kim, Sang Ouk,Yeom, Geun Young,Kim, Kyong Nam American Scientific Publishers 2015 Journal of Nanoscience and Nanotechnology Vol.15 No.10

<P>Some of the important issues of block copolymer (BCP) as an application to the potential low cost next generation lithography are thermal stability and deformation during pattern transfer process in addition to defect density, line edge/width roughness, etc. In this study, sulfur containing plasma treatment was used to modify the BCP and the effects of the plasma on the properties of plasma treated BCP were investigated. The polystyrene hole pattern obtained from polystyrene polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) was initially degraded when the polystyrene hole was annealed at 190 degrees C for 15 min. However, when the hole pattern was treated using sulfur containing plasmas using H2S or SF6 up to 2 min, possibly due to the sulfurization of the polystyrene hole surface, no change in the hole pattern was observed after the annealing even though there is a slight change in hole shapes during the plasma treatment. The optimized plasma treated polystyrene pattern showed the superior characteristics as the mask layer by showing better thermal stability, higher chemical inertness, and higher etch selectivity during plasma etching.</P>

Involvement of calcium-mediated apoptotic signals in H₂O₂-induced MIN6N8a cell death

Choi, Sung-E,Min, Se-Hee,Shin, Ha-Chul,Kim, Hyo-Eun,Jung, Min Whan,Kang, Yup Elsevier 2006 european journal of pharmacology Vol.547 No.1

<P><B>Abstract</B></P><P>Reactive oxygen species are believed to be the central mediators of beta-cell destruction that leads to type 1 and 2 diabetes, and calcium has been reported to be an important mediator of beta cell death. In the present study, the authors investigated whether Ca<SUP>2+</SUP> plays a role in hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>)-induced MIN6N8a mouse beta cell death. Treatment with low concentration H<SUB>2</SUB>O<SUB>2</SUB> (50?μM) was found to be sufficient to reduce MIN6N8a cell viability by 55%, largely via apoptosis. However, this H<SUB>2</SUB>O<SUB>2</SUB>-induced cell death was near completely blocked by pretreatment with BAPTA/AM (5?μM), a chelator of intracellular Ca<SUP>2+</SUP>. Moreover, the intracellular calcium store channel blockers, such as, xestospongin c and ryanodine, significant protected cells from 50?μM H<SUB>2</SUB>O<SUB>2</SUB>-induced cell death and under extracellular Ca<SUP>2+</SUP>-free conditions, 50?μM H<SUB>2</SUB>O<SUB>2</SUB> elicited transient [Ca<SUP>2+</SUP>]<SUB>i</SUB> increases. In addition, pharmacologic inhibitors of calpain, calcineurin, and calcium/calmodulin-dependent protein kinase II were found to have a protective effect on H<SUB>2</SUB>O<SUB>2</SUB>-induced death. Moreover, H<SUB>2</SUB>O<SUB>2</SUB>-induced apoptotic signals, such as c-JUN N-terminal kinase activation, cytochrome <I>c</I> release, caspase 3 activation, and poly (ADP-ribose) polymerase cleavage were all down-regulated by the intracellular Ca<SUP>2+</SUP> chelation. These findings show that [Ca<SUP>2+</SUP>]<SUB>i</SUB> elevation, possibly due to release from intracellular calcium stores and the subsequent activation of Ca<SUP>2+</SUP>-mediated apoptotic signals, critically mediates low concentration H<SUB>2</SUB>O<SUB>2</SUB>-induced MIN6N8a cell death. These findings suggest that a breakdown of calcium homeostasis by low level of reactive oxygen species may be involved in beta cell destruction during diabetes development.</P>