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991.
Ho-Jung Ryu Dal-Hee Bae Keun-Hee Han Seung-Yong Lee Gyoung-Tae Jin Jeong-Hoo Choi 《Korean Journal of Chemical Engineering》2001,18(6):831-837
The reaction kinetics of the oxygen carrier particles, which are used as bed material for a fluidized bed chemical looping
combustor (CLC), has been studied experimentally by a conventional thermal gravimetrical analysis technique. The weight percent of nickel
and nickel oxide in oxygen carrier particles and reaction temperature were considered as experimental variables. After oxidation
reaction, the pure nickel particle was sintered and unsuitable to use as fluidizing particles. The oxidation reaction rate
increased with increasing weight percent of nickel in oxygen carrier particles and reaction temperature. The rate of reduction
shows maximum point with weight percent of nickel oxide (57.8%) and reaction temperature (750 or 800 °C) increased. In this
work, the reaction between air and Ni/ bentonite particle was described by a special case of unreacted core model in which
the global reaction rate is controlled by product layer diffusion resistance. However, the reaction between CH4 and NiO/bentonite particle was described by unreacted core model in which the global reaction rate is controlled by chemical
reaction resistance. The temperature dependence of the effective diffusivity of oxidation reaction and reaction rate constant
of reduction reaction could be calculated from experimental data and fitted to the Arrhenius equation.
Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8-10, 2001), dedicated to Prof. H. S. Chun on the occasion of his
retirement from Korea University. 相似文献
992.
Effect of Heating Rate on the Sintering Behavior and the Piezoelectric Properties of Lead Zirconate Titanate Ceramics 总被引:3,自引:0,他引:3
The effect of heating rate on the sintering behavior and the piezoelectric properties of lead zirconate titanate (PZT) ceramics was investigated. Two different types of PZT (pure and doped with Nb2 O5 ) were sintered at 1150°C for 2 h with a wide range of heating rate (0.5°–100°C/min). The densification of pure PZT was improved significantly by increasing the heating rate. The improvement was attributed to the suppression of PbO volatilization and grain coarsening during heating. In contrast, the densification behavior of a PZT specimen doped with Nb2 O5 was not much influenced by the heating rate. These densification behaviors affected the piezoelectric properties of the specimens. The piezoelectric properties of pure PZT were enhanced significantly by increasing the heating rate, while those of doped specimens were improved only moderately. 相似文献
993.
Hyun Jin Kim Shin Young Kim Ji Hyae Lim Dong Wook Kwak So Yeon Park Hyun Mee Ryu 《International journal of molecular sciences》2015,16(12):29875-29888
The aim of this study was to evaluate quantitative aberrations of novel fetal-specific epigenetic markers in maternal plasma of pregnancies with hypertensive disorders. We compared the concentrations of DSCR3, RASSF1A, and SRY as cell-free fetal DNA markers in 188 normal pregnancies, 16 pregnancies with early-onset preeclampsia (EO-PE), 47 pregnancies with late-onset preeclampsia (LO-PE), and 29 pregnancies with gestational hypertension (GH). The concentrations of all markers were significantly correlated with gestational age (p < 0.001 for all). Strong positive correlations were also observed between DSCR3 and SRY (r = 0.471, p < 0.001), as well as between RASSF1A and SRY (r = 0.326, p = 0.015) and between DSCR3 and RASSF1A (r = 0.673, p < 0.001). The concentrations of DSCR3 and RASSF1A in the EO-PE were significantly higher at 24–32 weeks and onwards (p < 0.05 for both). In the LO-PE, DSCR3 and RASSF1A concentrations were significantly higher only at 33–41 weeks compared with the controls. The concentrations of all markers in the GH group were not significantly different from those in the control group. This study is the first demonstration that DSCR3 is a novel epigenetic marker that can be an alternative to the RASSF1A for the prediction of EO-PE. 相似文献
994.
Jong-Pyo KimJae-Jin Kim Byoung-Ryul MinKun Yong Chung Jong-Hoon Ryu 《Desalination》2002,143(2):159-172
A new vortex-flow membrane module with glass balls was developed to enhance the permeate flux through a flat-sheet membrane. As a preliminary study for a practical application of our new module configuration, the effects of operating parameters on the microfiltration of an oil-in-water emulsion were investigated. The glass balls used in this study had an average diameter of 4 mm and an average weight of 0.08 g, giving an average density of 2.39 g/ cm3. The number of glass balls inserted into the module was 500, leading to an effective volume fraction of 0.23. Under the same operating conditions, a significant flux enhancement was observed in the presence of glass balls. The flux enhancement due to the presence of glass balls increased with the feed flow rate. The influence of glass balls on the flux enhancement was found to be most significant when the emulsion was more highly concentrated, indicating that the mechanism of this enhancement is based on the disruption of the concentration boundary layer. 相似文献
995.
Jae-Kyoung Yang Wonhyeong Park Changseok Ryu Sun Jung Kim Do Il Kim Gon Seo Jong-Ho Kim Chang-Bok Chung 《应用聚合物科学杂志》2020,137(15):48559
The rheocurves of silica-filled styrene–butadiene/polybutadiene rubber (SBR/BR) compounds containing 3-octadecyltriethoxy silane (OTES) and bis-[triethoxysilylpropyl]tetrasulfide (TESPT) were investigated to examine the effects of silica content and silanes on silica flocculation during mixing and cure. SBR/BR compounds without curatives were also prepared to infer the effect of cure on silica flocculation. The maximum torque of the compounds could be deconvoluted to individual source torques such as silica flocculation during mixing and cure, crosslinking of rubber, and coupling between rubber and silica by assuming the independence of silica flocculation from cure and coupling. Torque due to silica flocculation increased with the silica content of the SBR/BR compounds, but its effect was significantly reduced by the addition of OTES or TESPT. TESPT suppressed silica flocculation and facilitated coupling, thus yielding enhanced tensile properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48559. 相似文献
996.
Eun Joo Jung Won Sup Lee Anjugam Paramanantham Hye Jung Kim Sung Chul Shin Gon Sup Kim Jin-Myung Jung Chung Ho Ryu Soon Chan Hong Ky Hyun Chung Choong Won Kim 《International journal of molecular sciences》2020,21(23)
Plant-derived natural polyphenols exhibit anticancer activity without showing any noticeable toxicities to normal cells. The aim of this study was to investigate the role of p53 on the anticancer effect of polyphenols isolated from Korean Artemisia annua L. (pKAL) in HCT116 human colorectal cancer cells. We confirmed that pKAL induced reactive oxygen species (ROS) production, propidium iodide (PI) uptake, nuclear structure change, and acidic vesicles in a p53-independent manner in p53-null HCT116 cells through fluorescence microscopy analysis of DCF/PI-, DAPI-, and AO-stained cells. The pKAL-induced anticancer effects were found to be significantly higher in p53-wild HCT116 cells than in p53-null by hematoxylin staining, CCK-8 assay, Western blot, and flow cytometric analysis of annexin V/PI-stained cells. In addition, expression of ectopic p53 in p53-null cells was upregulated by pKAL in both the nucleus and cytoplasm, increasing pKAL-induced cell death. Moreover, Western bot analysis revealed that pKAL-induced cell death was associated with upregulation of p53-dependent targets such as p21, Bax and DR5 and cleavage of PARP1 and lamin A/C in p53-wild HCT116 cells, but not in p53-null. Taken together, these results indicate that p53 plays an important role in enhancing the anticancer effects of pKAL by upregulating p53 downstream targets and inducing intracellular cell death processes. 相似文献
997.
Ahmed Fuwad Shakhawat Hossain Hyunil Ryu Mubashshir Ahmad Ansari Muhammad Saiful Islam Khan Kwang-Yong Kim Tae-Joon Jeon Sun Min Kim 《化学工程与技术》2020,43(9):1866-1875
Two chaotic micromixers (Models A and B) based on the split-and-recombine principle using multilayer microchannels are proposed and the mixing performance was analyzed numerically and experimentally for a wide range of Reynolds numbers. The fluid flow and mixing performance were numerically analyzed by solving Navier-Stokes equations. Micromixers were fabricated using a soft-lithography technique. As working fluids, water and a dye/water mixture were used. Quantitative and qualitative analyses were performed using confocal scanning microscopy and image processing techniques. The micromixers could enhance the mixing performance by expanding the interfaces between the working fluids to be mixed. The results confirm the superior mixing index of Model B compared to that of Model A. 相似文献
998.
Electrochemical performance of Li[Co0.1Ni0.15Li0.2Mn0.55]O2 modified by carbons as cathode materials
Jeong-Hun Ju Sung-Woo Cho Seung-Gi Hwang Su-Ryeon Yun Youngil Lee Han Mo Jeong Moon-Jin Hwang Kwang Man Kim Kwang-Sun Ryu 《Electrochimica acta》2011,56(24):8791
To enhance specific capacity, cycle performance and rate-capability of lithium-ion battery cathode materials, the Li[Co0.1Ni0.15Li0.2Mn0.55]O2 (LCMNO) is modified by coating them with amorphous carbons and by preparing nanocomposites with nanostructured carbons (carbon nanotube and graphene). The carbon-treated LCMNO powders and their cathodes are characterized by morphological observation, crystalline property analysis, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The LCMNO nanocomposite shows a superior discharge capacity of ca. 290 mAh g−1 at low C-rates, due to a greater number of active sites embedded by nanostructured carbon species. In contrast, the carbon-coated LCMNO shows higher discharge capacity in high rate regions due to the carbon-coated layer in the carbon-coated LCMNO, suppressing the side reactions and enhancing the electrical conductivity. 相似文献
999.
CuO‐added KNbO3‐BaZrO3 lead‐free piezoelectric ceramics with low loss and large electric field‐induced strain 下载免费PDF全文
Jongseong Park Dae‐Hyeon Kim Tae‐Gon Lee Sung‐Hoon Cho Su‐Jin Park Jungho Ryu Sahn Nahm 《Journal of the American Ceramic Society》2017,100(7):2948-2957
CuO‐added (1‐x)KNbO3‐x mol%BaZrO3 ceramics with 0.0≤x≤7.0 were sintered at 960°C. Large double polarization vs electric field (P‐E) and sprout‐shaped strain vs electric field (S‐E) hysteresis curves were obtained from the specimens with x≤2.0. They exhibited large polarizing electric fields (EP) owing to the presence of a large number of defect dipoles (PDs) that formed between Cu2+ ions and oxygen vacancies. Small double P‐E hysteresis curves were observed for the specimens with x≥3.0 with reduced EP because of the decreased number of PDs and the presence of a polymorphic phase structure containing both orthorhombic and pseudocubic structures. In particular, the specimen with x=5.0 exhibited a large strain of 0.16% at 8.0 kV/mm with a small EP of 1.2 kV/mm and good fatigue property: this specimen maintained a strain of 0.13% at 6.0 kV/mm after 106 cycles of 3.0 kV/mm. 相似文献
1000.
Preparation and properties of emulsifier‐/solvent‐free polyurethane‐acrylic hybrid emulsions for binder materials: Effect of the glycidyl methacrylate/acrylonitrile content 下载免费PDF全文
To obtain binder materials, emulsions of emulsifier‐/solvent‐free waterborne polyurethane‐acrylic hybrids with a fixed acrylic monomer content (30 wt %) were prepared in this study. This study focused on the effect of glycidyl methacrylate (GMA)/acrylonitrile (AN) wt % on the shelf stability, mean particle size and viscosity of hybrid emulsion samples, water swelling %/dynamic mechanical thermal properties/mechanical properties of hybrid film samples, and the failure mode and adhesive strength of binder materials prepared in this study. Characterization of the chemical structures of prepolymers, hybrid materials (binder materials), and atmospheric pressure plasma‐treated polyethylene (PE) has been performed by means of Fourier transformed infrared spectroscopy to determine the presence/disappearance/peak intensity change of functional groups. Various properties such as mean particle size, viscosity, Tg, water swelling %, hardness and mechanical properties, and failure mode and adhesive strength for leather/leather, control PE/leather, and plasma‐treated PE/leather were found to be significantly dependent on the weight ratio of GMA/AN. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44497. 相似文献