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451.
Jung Bae Park Soo Hyeon Bae Su‐Min Jang Won Jun Noh Jang‐Hee Hong Kee Dong Yoon Han Chang Kang Soo Kyung Bae 《Journal of separation science》2013,36(14):2306-2314
A simple, robust, and rapid LC–MS/MS method has been developed and validated for the simultaneous quantitation of clopidogrel and its active metabolite (AM) in human plasma. Tris(2‐carboxyethyl)phosphine (TCEP) was used as a reducing agent to detect the AM as a disulfide‐bonded complex with plasma proteins. Mixtures of TCEP and human plasma were deproteinized with acetonitrile containing 10 ng/mL of clopidogrel‐d4 as an internal standard (IS). The mixtures were separated on a C18 RP column with an isocratic mobile phase consisting of 0.1% formic acid in acetonitrile and water (90:10, v/v) at a flow rate of 0.3 mL/min. Detection and quantification were performed using ESI‐MS. The detector was operated in selected reaction‐monitoring mode at m/z 322.0→211.9 for clopidogrel, m/z 356.1→155.2 for the AM, and m/z 326.0→216.0 for the IS. The linear dynamic range for clopidogrel and its AM were 0.05–20 and 0.5–200 ng/mL, respectively, with correlation coefficients (r) greater than 0.9976. Precision, both intra‐ and interday, was less than 8.26% with an accuracy of 87.6–106%. The validated method was successfully applied to simultaneously analyze clinical samples for clopidogrel and its AM. 相似文献
452.
Sun L Noh KW Wen JG Dillon SJ 《Langmuir : the ACS journal of surfaces and colloids》2011,27(23):14201-14206
The interaction between silver and ionized and atomic gas was observed directly by in situ transmission electron microscopy with an environmental cell for the first time. The electron beam provides dual functions as the source of both gas ionization and imaging. The concentration of ionized gas was tuned via adjusting the current density of the electron beam. Oxidation of the silver is observed in situ, indicating the presence of ionized and/or atomic oxygen. The evolution of microstructure and phase constituents was characterized. Then the oxidation rate was measured, and the relationships among grain size, mass transport rate, and electron flux were characterized. The role of the electron beam is discussed, and the results are rationalized with respect to ex situ results from the literature. 相似文献
453.
Jung-Hyun Park Hyeryeung Noh Ji Won Park Kyong Ho Row Kwang Deog Jung Chae-Ho Shin 《Research on Chemical Intermediates》2011,37(9):1125-1134
A series of BiMoFe0.65P
x
oxide catalysts with varying phosphorous contents from 0.0 to 0.6 mol ratio were prepared by a co-precipitation method, and
oxidative dehydrogenation (ODH) was carried out to produce 1,3-butadiene (BD) from n-butenes. The physico-chemical properties of the oxide catalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy,
N2 sorption, and NH3 and 1-butene temperature-programmed desorption (TPD). Among the catalysts studied here, BiMoFe0.65P0.1 oxide catalyst showed the highest conversion and selectivity to BD. From the result of 1-butene TPD, the higher catalytic
activity is related to the amount of weakly bounded intermediate and the desorbing temperature of strongly bounded intermediates.
Also, the higher catalytic activity likely originates from the acidity of the BiMoFe0.65P0.1 oxide catalyst; its acidity was higher than that of phosphorous-free oxide catalyst and further contained other oxide catalysts.
BiMoFe0.65P0.1 oxide catalyst is stable and no significant deactivation for 100 h ODH reaction was shown. 相似文献
454.
Yuvaraj Haldorai Pham Quang Long Seok Kyun Noh Won Seok Lyoo Jae‐Jin Shim 《先进技术聚合物》2011,22(6):781-787
Ultrasonically assisted in situ emulsion polymerization was used to prepare electrically conducting copolymer poly(aniline‐co‐p‐phenylenediamine) [poly(Ani‐co‐pPD)] and silica (SiO2) nancomposites. This approach can solve problems in the dispersion and stabilization of SiO2 nanoparticles in the copolymer matrix. It was found that the aggregation of SiO2 nanoparticles could be reduced under ultrasonic irradiation. Scanning transmission electron microscopy (STEM) confirmed that the resulting poly(Ani‐co‐pPD)/SiO2 nanocomposite particles were spherical in shape, in which SiO2 nanoparticles were well dispersed. The comonomer molecules were absorbed on the surface of SiO2 particles and then polymerized to form core–shell nanocomposite. The incorporation of SiO2 in the nanocomposite was supported by Fourier transform infrared spectroscopy (FT‐IR). UV‐visible spectra of the diluted colloid dispersion of nanocomposite particles were similar to those of the neat copolymer. Conductivity of nanocomposites was higher than the value obtained for the neat copolymer. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
455.
Zhigang Xue Hyun Sook Oh Seok Kyun Noh Won Seok Lyoo 《Macromolecular rapid communications》2008,29(23):1887-1894
The iron(III)‐catalyzed atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was successfully employed using tributylphosphine (TBP) and trimethylphosphite (TMP) as ligands in the absence of a reducing agent. The effects of solvent and initiator on polymerization of MMA were investigated. Most of the polymerizations with these ligands were well controlled with a linear increase in the number average molecular weights ( ) versus conversion and relatively low molecular weight distribution ( = 1.2–1.4) throughout the reactions, and the measured weights matched with the predicted values. The ethyl 2‐bromoisobutyrate (EBriB) initiated ATRP of MMA with the FeBr3/TBP or FeBr3/TMP catalytic system was better controlled in toluene than in the other solvents used in this study at 80 °C.
456.
N.D. Kim T.S. Kang J.H. Je H.J. Kim D.Y. Noh J.W. Chung 《Applied Physics A: Materials Science & Processing》2008,91(1):53-57
We have investigated the atomic arrangement of a barium (Ba)-induced Si(111)-3×2 surface by using surface-sensitive synchrotron X-ray scattering. In-plane fractional-order reflections obtained from three rotational domains of 3×1 symmetry have been used to examine several competing structural models including the honeycomb-chain-channel (HCC) and the double-π-bonded chain (DπC) models. By fitting two different data sets, both the goodness-of-the fits χ2 and the residuum R-factor strongly favor the HCC over the DπC model. We conclude that a Ba-paired HCC structure with a \(\frac{1}{3}\) monolayer of Ba coverage best describes the Ba-induced 3×2 surface with a Ba-Ba interatomic spacing d?=?1.93 Å. 相似文献
457.
We investigated temperature dependent optical spectra of the one-dimensional chain compound Sr2CuO3. The charge transfer transition polarized along the chain direction shows a strongly asymmetric line shape as expected in one-dimensional extended Hubbard model. At low temperature, the charge transfer peak shows a large blueshift and reveals additional sharp peaks at the gap. Even though many spectroscopic studies suggest that this material cannot have a bound exciton based on the one-dimensional extended Hubbard model, we attribute the additional sharp peaks to excitons, which come to exist due to the long-range Coulomb interaction. 相似文献
458.
Su Jung Noh 《Journal of magnetism and magnetic materials》2010,322(21):3601-3604
We report micromagnetic modeling results of current induced domain wall (DW) motion in magnetic devices with perpendicular magnetic anisotropy by solving the Landau-Lifschitz-Gilbert equation including adiabatic and non-adiabatic terms. A nanostripe model system with dimensions of 500 nm (L)×25 nm (W)×5 nm (H) was selected for calculating the DW motion and its width, as a function of various parameters such as non-adiabatic contribution, anisotropy constant (Ku), saturation magnetization (Ms), and temperature (T). The DW velocity was found to increase when the values of Ku and T were increased and the Ms value decreased. In addition, a reduction of the domain wall width could be achieved by increasing Ku and lowering Ms values regardless of the non-adiabatic constant value. 相似文献
459.
By assuming that a dark component (dark energy) in the universe strictly obeys the holographic principle, that is, its entropy is one fourth of the apparent horizon, we find that the existence of the other dark component (dark matter) is compulsory, as a compensation of dark energy, based on the first law of thermodynamics. By using the method of dynamical system analysis, we find that there exists a stable dark energy-dark matter scaling solution at late time, which is helpful to solve the coincidence problem. For reasonable parameters, the deceleration parameter is well consistent with current observations. 相似文献
460.