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21.
2D Materials: Rotation‐Misfit‐Free Heteroepitaxial Stacking and Stitching Growth of Hexagonal Transition‐Metal Dichalcogenide Monolayers by Nucleation Kinetics Controls (Adv. Mater. 25/2015) 下载免费PDF全文
22.
Modulation of the band gap energy and diameter of quantum dots (QDs) formed in glasses is important to achieve the optimized performance for applications as infrared light sources, lasers, saturable absorbers, etc. Absorption and photoluminescence of PbS QDs were extended into mid-infrared wavelength range in glasses containing small amount of lead but oversaturated with sulfur. Dual-band photoluminescence of PbSe QDs was prepared in oxyfluoride glass-ceramics containing BaF2 nanocrystals. By introducing SnO in the glasses, alloyed Pb1-xSnxSe QDs with smaller band gap energies were formed in glasses, and mid-infrared photoluminescence of Pb1-xSnxSe QDs at ~2570 nm in wavelength was achieved. 相似文献
23.
Sung Jae Won Rendi Kurniawan Dae Kyung Kang Joong Sik Heo 《Journal of Mechanical Science and Technology》2018,32(9):4173-4181
The surge in demand for natural resources has shifted the focus of the international community toward the development of oil sands, shale oil, shale gas and other non-traditional energy sources. In extreme environments, materials used in petroleum gas plant modules are accompanied by various problems caused by low-temperature brittleness such as damage, corrosion and wear. Many researchers have been conducting studies to discover a suitable material whose lifespan could be improved by performing characteristics analyses and performance assessments. In this study, a material characteristics assessment was conducted based on a wear resistance test on materials that are commonly used at oil sands plants. Prior to a wear resistance test, a chemical composition analysis was performed on each of the specimens, and tensile, impact, hardness and corrosion tests were carried out to examine the correlation between their results with the results of the wear resistance test. Each test was performed according to ASTM G 105 standards, and the change in weight according to wear length was analysed for each material to determine the related tendencies. In addition, the results of the wear test were derived by analysing the change in the mass of the specimen before and after the test, and the surface roughness was assessed to analyse the performance related to wear and define the service life. The aim was to use these results to select a material that would be suitable for the abrasive environment of the key equipment and materials of plants. 相似文献
24.
Quantitative analysis of microbial community structure in two-phase anaerobic digesters treating food wastewater 总被引:1,自引:0,他引:1
Woong Kim Byung-Gon Ryu Sungwhan Kim Sung-Woon Heo Donghyun Kim Jungmin Kim Haechan Jo Jong-Hee Kwon Ji-Won Yang 《Korean Journal of Chemical Engineering》2014,31(3):381-385
An acidogenic reactor with a 0.5-L working volume and a methanogenic digester with a 5-L of working volume were operated for 150 days on a continuous mode to investigate the structure of a microbial community during food wastewater treatment. During the steady state of anaerobic digestion, volatile solids (VS) removal efficiency in the pilot plant was approximately 65%. The bacterial population was higher than any other methanogens detected during the entire anaerobic process and treatment of raw food wastewater. Methanomicrobiales (MMB), Methanosarcinales (MSL), and Methanobacteriales (MBT) were detected during digestion. The methanogenic population present in the acidogenic reactor was directly affected by the archaeal community in raw food wastewater. However, the shift of microbial community in the methanogenic digester was relatively gradual. The performance of methanogenic digester might be more related to the change of microbial metabolism affected by the physicochemical properties of the input substrate. 相似文献
25.
26.
Seok Heo Geum Joo Yoo Ji Yeon Choi Hyoung Joon Park Sung-Kwan Park 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(11):1627-1636
A novel, stable, simple and specific ultra-performance liquid chromatography method with ultraviolet detection (205 nm) for the simultaneous analysis of 25 anti-hypertensive substances was developed. The method was validated according to the International Conference of Harmonisation guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and stability. From the ultra-performance liquid chromatography results, we identified the LOD and LOQ of solid samples to be 0.20–1.00 and 0.60–3.00 μg ml?1, respectively, while those of liquid samples were 0.30–1.20 and 0.90–3.60 μg ml?1, respectively. The linearity exceeded 0.9999, and the intra- and inter-day precisions were 0.15–6.48% and 0.28–8.67%, respectively. The intra- and inter-day accuracies were 82.25–111.42% and 80.70–115.64%, respectively, and the stability was lower than 12.9% (relative standard deviation). This method was applied to the monitoring of 97 commercially available dietary supplements obtained in Korea, such as pills, soft capsules, hard capsules, liquids, powders and tablets. The proposed method is accurate, precise and of high quality, and can be used for the routine, reproducible analysis and control of 25 anti-hypertensive substances in various dietary supplements. The work presented herein may help to prevent incidents related to food adulteration and restrict the illegal food market. 相似文献
27.
Seung-Hong Lee Jung-In Choi Soo-Jin Heo Mi-Hwa Park Pyo-Jam Park Byong-Tae Jeon Se-Kwon Kim Ji-Sook Han You-Jin Jeon 《Food science and biotechnology》2012,21(1):239-246
Pancreatic β cells are very sensitive to oxidative stress and this may play an important role in β cell death in diabetes.
The protective effect of diphlorethohydroxycarmalol (DPHC), one of phlorotannin polyphenol compound purified from pae (Ishige okamurae) against high glucoseinduced oxidative stress was investigated using RINm5F pancreatic β cells. High glucose (30 mM) treatment
induced RINm5F pancreatic β cells cell death, but DPHC, at concentration 10 or 50 μg/mL, significantly inhibited the high
glucose-induced glucotoxicity and apoptosis. Furthermore, treatment with DPHC dose-dependently decreased thiobarbituric acid
reactive substances (TBARS), intracellular reactive oxygen species (ROS) generation and nitric oxide level increased by high
glucose. In addition, DPHC treatment increased activities of antioxidant enzymes including catalase (CAT), superoxide dismutase
(SOD), and glutathione peroxidase (GSH-px) in high glucose pretreated RINm5F pancreatic β cells. DPHC treatment improved the
secretory responsiveness following stimulation with glucose. These findings indicate that DPHC might be used as potential
nutraceutical agent which will protect the glucotoxicity caused by hyperglycemia-induced oxidative stress associated with
diabetes. 相似文献
28.
Lee JS Heo GY Lee JW Oh YJ Park JA Park YH Pyun YR Ahn JS 《International journal of food microbiology》2005,102(2):143-150
A polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique was used to determine the microfloral composition during the fermentation of kimchi, a traditional Korean fermented vegetable food. The kimchi was fermented at 10 degrees C or 20 degrees C for 30 or 20 days, respectively. DGGE of the partially amplified 16S rDNA was performed and the most intense bands sequenced. The application of this culture-independent molecular technique determined that the lactic acid bacteria Weissella confusa, Leuconostoc citreum, Lactobacillus sakei, and Lactobacillus curvatus were the main microorganisms responsible for kimchi fermentation. 相似文献
29.
Se Ho Park Dong Chin Lee Jong Heo Hyoun Soo Kim 《Journal of the American Ceramic Society》2000,83(5):1284-1286
Fluorescence emissions at both 1.31 and 1.55 μm communication windows were observed from Pr3+ /Er3+ codoped Ge-As-Ga-S glasses with a single wavelength pumping at 986 nm. The lifetime of the Er3+ :4 I 11/2 level decreased as the Pr3+ concentration increased, and that of the Pr3+ :1 G 4 level increased as the Er3+ concentration increased. Energy transfer from the Er3+ :4 I 11/2 level to the Pr3+ :1 G 4 level was responsible for emission of the 1.31 μm fluorescence from the Pr3+ :1 G 4 level. Ge-As-Ga-S glasses that have been doped with Pr3+ and Er3+ cations are promising amplifier materials for both 1.31 and 1.55 μm communication windows. 相似文献
30.
Shankara S. Kalanur Jaewoo Heo Il-Han Yoo Hyungtak Seo 《International Journal of Hydrogen Energy》2017,42(26):16901-16908
The ultrathin two-dimensional (2D) nanomaterials display unique properties owing to their ultrahigh specific surface area and strong quantum confinement of electrons in two dimensions. In this work, we fabricated a rapid gasochromic and electrical hydrogen sensing system containing 2D WO3 and Pd nanoparticles. 2D WO3 nano-plates (NP) are synthesized using sol–gel method and Pd nanoparticles are coated on WO3 by green photochemical deposition method. The sensor is fabricated by dispersing the 2D WO3/Pd composite on filter paper. In presence of hydrogen gas, 2D WO3/Pd composite produces visible change in color from brown to dark blue. With the fabricated sensor, as low as 0.1% H2 gas in air at room temperature can be easily detected using electrical sensing scheme whereas for higher concentration from 1 to 100%, eye readable gasochromic scheme can be utilized. The use of 2D WO3 decreased the response time in great deal compared to WO3 nanoparticles indicating the advantage of 2D structure in fabricating rapid response H2 sensors. The proposed method is simple and can be easily employed to large scale fabrication system for commercial applications. 相似文献