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171.
172.
Joonho Lee Joongchul Park Yunkyum Kim Sun-Ho Jeon 《Journal of Materials Science》2010,45(8):2112-2117
The wettability of low-carbon, 0.3 wt%Si–0.4 wt%Mn interstitial-free steel by liquid zinc at 450 °C was investigated using
the dispensed sessile drop method. Before the wetting tests, the steel samples were annealed in a 15%H2–Ar gas atmosphere at three different dew points, namely −60, −40, and 0 °C. It was found that as the dew point was increased
from −60 to −40 °C, the wettability became poorer. However, as the dew point was increased further to 0 °C, the wettability
was dramatically improved and was better than that of −60 °C. In order to understand the dramatic change in wettability, the
surfaces of the steel samples after annealing were analyzed with SEM and TEM. It was found that the surface oxide changed
from randomly distributed hemisphere particles of 20–30-nm high on a very thin oxide film to a film-like layer ~15-nm thick
as the dew point was increased from −60 to −40 °C, and at the dew point of 0 °C, internal oxidation was so pronounced that
a very thin surface oxide layer 1–2-nm thick was formed. It was believed that the improvement of the wettability at the dew
point of 0 °C was caused by the short diffusion distance in the surface oxide layer. 相似文献
173.
R. Nirmala Hak Yong Kim R. Navamathavan Chaun Yi Jeong Jin Won Kyungsoo Jeon Ayman Yousef R. Afeesh Mohamed El-Newehy 《Ceramics International》2012,38(6):4533-4540
SnO2 doped TiO2 electropsun nanofiber photocatalysts were successfully prepared by means of electrospinning process. The surface morphology, structure and optical properties of the resultant products were characterized by field-emission electron microscopy (FE-SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy, photoluminescence (PL) and cathodoluminescence (CL) techniques. The utilized physiochemical analyses indicated that the introduced SnO2 doped TiO2 nanofibers have a smooth surface and uniform diameters along their lengths. The photocatalytic performance of the composite nanofibers was tested for degradation of methylene blue (MB) and methyl orange (MO) dye solution under ultraviolet (UV) irradiation. Under the UV irradiation, the photocatalytic reaction rate in case of utilizing SnO2-doped TiO2 nanofibers was rapidly increased than that of the pristine TiO2 nanofibers. Overall, this study demonstrates cheap, stable and effective material for photocatalytic degradation at room temperature. 相似文献
174.
An accelerated testing method for barium titanate (BaTiO3) dielectrics was proposed to elucidate deterioration behavior of dielectric constant based on the life-temperature relation. The accelerated degradation test (ADT) which was designed using various temperature ranges below and above Curie temperature (Tc) was focused on the optimized composition of dysprosium (Dy) and thulium (Tm) co-doped BaTiO3. The statistical analysis of the failure time data was performed to determine the optimum distribution as a goodness-of-fitness test. A scale parameter (η) and activation energy (Eα) were calculated in order to predict the life time of the co-doped BaTiO3, and there was difference between the expected life times according to the acceleration temperature rating of the ADT. The difference of deterioration mechanism around Tc could be deduced from the change of lattice parameter and polarization behavior. The drastic decrease of tetragonality and ferroelectric property caused by the phase transition of the co-doped BaTiO3 was verified in the temperature above Tc. Accordingly, the acceleration factor over Tc should be considered as reliability study of the BaTiO3 dielectrics for multilayer ceramic capacitors (MLCCs). 相似文献
175.
Young-Deuk Jeon Seung-Hoon Lee 《Electronics letters》1999,35(23):1990-1991
Acquisition time minimisation techniques using a two-stage amplifier for high-speed analogue signal processing in mixed-mode circuits are presented. The proposed techniques reduce overshoots and undershoots of the amplifier by adjusting its transconductance and achieve high-speed performance with little modification to the conventional amplifier architecture. The measured signal-to-noise-and-distortion ratio of the prototype 12 bit CMOS ADC based on the proposed techniques is improved by >5 dB at a 50 MHz sampling clock 相似文献
176.
12 nm tunable WDM source using an integrated laser array 总被引:1,自引:0,他引:1
Pezeshki B. Mathur A. Zou S. Jeon H.-S. Agrawal V. Lang R.L. 《Electronics letters》2000,36(9):788-789
A 12 nm tunable source with up to 15 mW fibre coupled power has been fabricated by integrating four DFB lasers and a booster amplifier to provide a single output. High-yield and low-cost techniques are used, such as quarter-wave-shifted phase-masks for wavelength definition and an integration technique with only two regrowths 相似文献
177.
Gyeong-Im Jeon Eunju Park Hye-Jin Lee Myung-Hee Kang 《Food science and biotechnology》2010,19(2):511-516
Recently, licorice (Glycyrrhiza uralensis Fisch., GU) has demonstrated significant in vitro and in vivo antioxidant properties. In this study, it was tested that a daily regimen of supplementation with water extract of GU would
ameliorate oxidative stress and whether effects were modulated by the glutathion-S-transferase (GST) polymorphisms. Forty healthy male smokers aged 20–60 were divided evenly into 2 groups and given either
260 mL of GU extracted with hot water or 260 mL of oligosaccharide based placebo every day for 8 weeks without any change
of usual food intake, and blood samples were drawn before and after the intervention. Eight weeks of GU supplementation significantly
decreased plasma conjugated dienes (a maker for lipid peroxidation) in GSTM1 positive subjects, but not in the GSTM1 null
genotype group. Our finding suggests that consumption of licorice water extract might be effectively decreasing lipid peroxidation
in the subgroup of smokers who have GSTM1 gene. 相似文献
178.
Siwoo Park Ki-Choon Choi Minghao Fang Yung Chul Lim Young-Mi Jeon Jeong-Chae Lee 《Food science and biotechnology》2011,20(4):1125-1131
This study used in vitro and in vivo experimental models to investigate the anti-inflammatory potential of the butanol fraction of red bean ethanol extract (BF-RBEE),
which contains the biologically active molecule catechin-7-β-d-glucopyranoside. Treatment with BF-RBEE inhibited nitric oxide production in lipopolysaccharide (LPS)-stimulated macrophages
through suppression of extracellular signalregulated kinase and IκBα activation. In an in vivo murine sepsis model, oral administration of BF-RBEE improved mouse survival. Specifically, the survival rate of mice injected
with LPS was 0 and 40% in ICR and BALB/c mice, respectively, whereas the survival of mice co-treated with BF-RBEE was 100%
in both mouse types. This increase in survival with the BF-RBEE administration was correlated with decreased tumor-necrosis
factor-α and interferon-γ and increased interleukin-10. Oral administration of BF-RBEE also inhibited total and ovalbumin-specific
IgE production in experimental mice. These results suggest the possible usefulness of red beans in the treatment of inflammatory
diseases. 相似文献
179.
Seong Je Jeon Sang Man Koo Seon Am Hwang 《Solar Energy Materials & Solar Cells》2009,93(6-7):1103-1109
Screen-printed n+–p–p+ solar cells were fabricated on Cz single crystalline Si material, with a 45 Ω/sq emitter and PECVD SiNx antireflective coating with a thickness of 700 Å, using different Ag pastes and commercial leaded reference paste (CN33-462, Ferro Corp.). Ag and Al contacts were co-fired using a mass-production line equipped with mesh belt conveyer furnace systems (Centrotherm thermal solution GmbH & Co. KG). The average results for single crystalline Si solar cells (156 cm2) are: Isc=5.043 A, Voc=0.621 V, Rs=0.0087 Ω, Rsh=15.3 Ω, FF=0.773, and Eff=16.45%. Rsh and fill factor values of fabricated cells were slightly higher when compared with the commercial leaded Ag paste, although cells were fabricated by metallizing the lead-free silver pastes. For the lead-free Ag paste used in this study, the line pattern continuity is retained with improved edge definition in sharp contrast to that of reference Ag paste. Average value of Rs was also equivalent approximately to that of the leaded Ag paste. 相似文献
180.