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111.
Jin Woo Kook In Seop Gwak You Ra Gwak Myung Won Seo See Hoon Lee 《Korean Journal of Chemical Engineering》2017,34(12):3092-3101
Characteristics of Char-CO2 gasification were compared in the temperature range of 1,100–1,400 °C using a thermogravimetric analyzer (TGA) for petroleum coke, coal chars and mixed fuels (Petroleum coke/coal ratios: 0, 0.25, 0.5, 0.75, 1). The results showed that reaction time decreased with increasing gasification temperature, BET surface area and alkali index of coal. Mixed fuels composed of petroleum coke/coal exhibited reduced activation energies. Modified volumetric reaction model and shrinking core model might be suitably matched with experimental data depending on coal type and petroleum coke/coal ratio. Rate equations were suggested by selecting gas-solid reaction rate models for each sample that could simulate CO2 gasification behavior. 相似文献
112.
High thermal conductivity of spark plasma sintered silicon carbide ceramics with yttria and scandia 下载免费PDF全文
Yu‐Kwang Seo Young‐Wook Kim Toshiyuki Nishimura Won‐Seon Seo 《Journal of the American Ceramic Society》2017,100(4):1290-1294
A fully dense SiC ceramic with a room‐temperature thermal conductivity of 262 W·(m·K)?1 was obtained via spark plasma sintering β‐SiC powder containing 0.79 vol% Y2O3‐Sc2O3. High‐resolution transmission electron microscopy revealed two different SiC‐SiC boundaries, that is, amorphous and clean boundaries, in addition to a fully crystallized junction phase. A high thermal conductivity was attributed to a low lattice oxygen content and the presence of clean SiC‐SiC boundaries. 相似文献
113.
Dowan Kim Yunho Lee Jongchul Seo Haksoo Han Sher Bahadar Khan 《Polymer International》2013,62(2):257-265
Tetrapod zinc oxide whiskers (TZnO‐Ws) were successfully synthesized via a thermal oxidation method and confirmed using Fourier transform infrared spectroscopy, X‐ray diffraction and scanning electron microscopy. A series of poly(urethane acrylate) (PUA)/TZnO‐W composite films with various TZnO‐W contents were prepared via a UV curing method and their physical properties were investigated to understand their possible use as packaging materials. The morphological, thermal, mechanical, antibacterial and barrier properties of the PUA/TZnO‐W composite films were interpreted as a function of TZnO‐W content. The thermal stability, barrier properties and antibacterial properties of the composite films, which were strongly dependent upon their chemical and morphological structure, were enhanced as the TZnO‐W content increased. The oxygen transmission rate and water vapor transmission rate decreased from 614 to 161 cm3 m?2 per day and 28.70 to 28.16 g m?2 per day, respectively. However, the mechanical strength of the films decreased due to the low interfacial interaction and poor dispersion with high TZnO‐W loading. The enhanced barrier properties and good antibacterial properties of the PUA/TZnO‐W composite films indicate that these materials are potentially suitable for many packaging applications. However, further studies are needed to increase the compatibility of polymer matrix and filler. © 2012 Society of Chemical Industry 相似文献
114.
Donglei Wei Beiling Yuan Yanlin Huang Taiju Tsuboi Hyo Jin Seo 《Journal of the American Ceramic Society》2013,96(7):2167-2171
Sm3+‐doped glass 13SrO–2Bi2O3–5K2O–80B2O3 was fabricated by the conventional melt‐quenching technique. The glass‐ceramics were obtained by heating the as‐prepared glasses in air atmosphere at selected temperatures 550°C, 600°C, 615°C, and 650°C, respectively. The luminescence spectra of both Sm3+ and Sm2+ were detected in the ceramic heated at 650°C where crystalline phase is formed. The as‐prepared glass and the ceramics heated at 550°C, 600°C, and 615°C show only the emission due to Sm3+. In the sample heated at 650°C in air atmosphere, however, part of Sm3+ ions was converted to Sm2+, giving rise to sharp emission lines which are characteristic of Sm2+ in crystalline state. It is suggested that Sm2+ ions are located at Sr2+ site in the ceramic while Sm3+ ions are located at Bi3+ sites. The Sm2+‐doped glass‐ceramic has a high optical stability because the fluorescence intensity decreases by only about 8% of its initial value upon excitation at 488 nm Ar+ laser. 相似文献
115.
Se Woong Lee Seong Wook Lim Soon Hee Park Kwang Ha Keun Sik Kim Se Min Oh Jin Yong Lee Gon Seo 《Korean Journal of Chemical Engineering》2013,30(12):2241-2247
The reaction of m-xylylenediamine (mXD) with carbon dioxide was examined and its feasibility as a sequestration material of carbon dioxide was discussed. The reaction was monitored by using the FT-IR and gravitational methods, while the crystalline structure of the reaction product was investigated with elemental analysis, powder Xray diffraction, single crystallography, and 13C MAS NMR spectroscopy. Even at ambient temperature, mXD reacted with carbon dioxide of low partial pressure in the atmosphere and produced a 1: 1 molar adduct which appeared as a white crystalline material. The hydrogen bonds that formed between the adduct molecules resulted in the formation of a stable crystal. The sequestration capacity of mXD was very great, ~280 mg g mXD ?1 below 50 °C. An adsorbent prepared by dispersing mXD on silica was capable of capturing carbon dioxide, but it could be regenerated by evacuating at 25 °C. 相似文献
116.
Sung-Chul Seo Sergey A. Grinshpun Yulia Iossifova Detlef Schmechel Carol Y. Rao Tiina Reponen 《Aerosol science and technology》2013,47(8):794-803
A field-compatible collection system was developed and tested for the collection and analysis of fungal fragments. The new collection system consists of two types of Sharp-Cut cyclone samplers (PM 2.5 and PM 1.0 ) and an after-filter. Fungal particles are collected into three size fractions: (1) spores ( > 2.5 μ m); (2) a fragment-spore mixture (1.0–2.5 μ m); and (3) submicrometer-sized fragments ( < 1.0 μ m). The system was laboratory-tested using polystyrene latex (PSL) particles and particulate matter aerosolized from sporulating Aspergillus versicolor and Stachybotrys chartarum cultures. In addition to the particle count measured with direct-reading instruments, the (1 → 3)- β -D-glucan content in each size fraction was determined with the Limulus Amebocyte Lysate (LAL) assay. Experiments conducted with PSL particles showed that the 50% cut-off values of the two cyclone samplers under the test conditions were 2.25 μ m and 1.05 μ m, respectively. No particle bounce onto the after-filter was observed when the total particle number entering the collection system was kept below 1.6 × 10 8 . The (1 → 3)- β -D-glucan assay of samples aerosolized from both fungal species suggested that surface area is an important factor for determining the (1 → 3)- β -D-glucan content in the entire size-range of particles. In conclusion, the new methodology is a promising tool for separating and analyzing fungal fragment samples. 相似文献
117.
A new blue-emitting nanophosphor of Eu2+-activated BaCa2Al8O15 was synthesized by the Pechini method. The phosphors were investigated by X-ray powder diffraction (XRD) measurement and confirmed to be a pure crystalline phase of BaCa2Al8O15. The photoluminescence excitation and emission spectra, the luminescence decay and the color coordinates were taken to investigate the luminescence characteristics. The dependence of luminescence intensities BaCa2Al8O15:Eu2+ on the doping concentrations was investigated. This nanophosphor can be efficiently excited by UV light and presents bright blue luminescence. Under the same conditions, the light yield of BaCa2Al8O15:Eu2+ is about 1.2 times higher than that of blue-emitting phosphor BaMgAl10O17:Eu2+. Eu2+-activated BaCa2Al8O15 nanophosphor exhibits the long-lasting phosphorescence, which was analyzed by measuring the afterglow decay curves. The co-doped Eu3+ ions and some defects were suggested to be the possible trap-centers. 相似文献
118.
Random or tapered solution styrene–butadiene copolymer (SSBR) is very difficult to prepare in an isothermal batch process without the use of polar modifiers because of the diverse reactivity ratios of the styrene and the butadiene in hydrocarbon solvents. In the presence of polar modifiers, the random SSBR can be synthesized by anionic living polymerization with the variety of microstructures, which results in the change of glass transition temperature (Tg). This article will discuss the use of sodium dodecylbenzene sulfonate as a polar modifier in isothermal batch process that controls the microstructure of the SSBR resulting in a random as well as tapered SSBR with low Tg (?67°C to ?80°C). The Tg of SSBR was controlled by the styrene content rather than the microstructure of polybutadiene. Physical properties of SSBR compounding were discussed for tire tread applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
119.
Young‐Min Cho Hyung‐Jae Lee Yun Heo Shin‐Hye Park Si‐Yoong Seo Jae‐Hong Han Tae‐Il Son 《应用聚合物科学杂志》2013,129(4):2161-2170
Carboxymethyl starch was modified by the incorporation of an azidophenyl group to prepare photoreactive starch, and characterized by Fourier transform infrared reflectance (FT‐IR), proton nuclear magnetic resonance (1H‐NMR), and ultraviolet (UV) spectroscopy. Photo‐irradiation immobilized the Az‐starch on a polystyrene plate and it was stably retained on the surface. The protein containing immobilized Az‐starch was also immobilized on a stripe micropatterned plate. UV irradiation time and Az‐starch concentration were used to alter the physical properties of Az‐starch and consequently control the rate of epidermal growth factor (EGF) release. The Az‐starch that released growth factor was not cytotoxic to 3T3‐L1 fibroblast cells, and the immobilized EGF maintained its activity and induced cellular proliferation in vitro. These results suggest that Az‐starch could be useful as a clinical synthetic material for medical applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
120.
Ramamourthy Gopal Jong Kook Lee Jun Ho Lee Young Gwon Kim Gwang Chae Oh Chang Ho Seo Yoonkyung Park 《International journal of molecular sciences》2013,14(1):2190-2202
In a previous study, we synthesized a series of peptides containing simple sequence repeats, (KW)n–NH2 (n = 2,3,4 and 5) and determined their antimicrobial and hemolytic activities, as well as their mechanism of antimicrobial action. However, (KW)5 showed undesirable cytotoxicity against RBC cells. In order to identify the mechanisms behind the hemolytic and cytotoxic activities of (KW)5, we measured the ability of these peptides to induce aggregation of liposomes. In addition, their binding and permeation activities were assessed by Trp fluorescence, calcein leakage and circular dichrorism using artificial phospholipids that mimic eukaryotic liposomes, including phosphatidylcholine (PC), PC/sphingomyelin (SM) (2:1, w/w) and PC/cholesterol (CH) (2:1, w/w). Experiments confirmed that only (KW)5 induced aggregation of all liposomes; it formed much larger aggregates with PC:CH (2:1, w/w) than with PC or PC:SM (2:1, w/w). Longer peptide (KW)5, but not (KW)3 or (KW)4, strongly bound and partially inserted into PC:CH compared to PC or PC:SM (2:1, w/w). Calcein release experiments showed that (KW)5 induced calcein leakage from the eukaryotic membrane. Greater calcein leakage was induced by (KW)5 from PC:CH than from PC:SM (2:1, w/w) or PC, whereas (KW)4 did not induce calcein leakage from any of the liposomes. Circular dichroism measurements indicated that (KW)5 showed higher conformational transition compared to (KW)4 due to peptide-liposome interactions. Taken together, our results suggest that (KW)5 reasonably mediates the aggregation and permeabilization of eukaryotic membranes, which could in turn explain why (KW)5 displays efficient hemolytic activity. 相似文献