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991.
Kim HG Kim GS Park S Lee JH Seo ON Lee SJ Kim JH Shim JH Abd El-Aty AM Jin JS Shin SC 《Biomedical chromatography : BMC》2012,26(4):464-470
A mixture of flavonoid components was isolated from the fruit peel of three varieties of citrus native to Republic of Korea, Citrus leiocarpa Hort. ex Tanaka (CLHT), Citrus aurantium L. (CAL) and Citrus erythrosa Hort. (CEH), via 70% methanol extraction followed by ethyl acetate elution over a silica gel cartridge. The flavonoid components of the mixture were analyzed via high‐performance liquid chromatography–tandem mass spectrometry (HPLC‐MS/MS) in positive‐ion mode and a comparison of the reported data. Among 17 characterized components, two flavanones, four flavones and two coumarin derivatives in the fruit peel of the three varieties were identified for the first time. The individual characterized components were quantified via HPLC‐UV. The flavanones dominated in CAL, whereas the flavones prevailed in CLHT and CEH. The antioxidant activity of the flavonoid mixture of the fruit peel was determined via DPPH?, ABTS?+ and reducing power assays. The antioxidant activity of CEH and CAL was greater than that of CLHT. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
992.
A theoretical method is proposed to predict and evaluate collision-induced derailments of rolling stock by using a simplified wheelset model and is verified with dynamic simulations. Because the impact forces occurring during collision are transmitted from the car body to the bogies and axles through suspensions, rolling stock leads to derailment as a result of the combination of horizontal and vertical impact forces applied to the axle and a simplified wheelset model enforced at the axle can be used to theoretically formulate derailment behaviors. The derailment type depends on the combination of the horizontal and vertical forces, the flange angle and the friction coefficient. According to collision conditions, wheel-climb, wheel-lift or roll-over derailment can occur between the wheel and the rail. In this theoretical derailment model of a simplified wheelset, the derailment types are classified as Slip-up, Slip/roll-over, Climb-up, Climb/roll-over and pure Roll-over according to the derailment mechanisms between the wheel and the rail and the theoretical conditions needed to generate each derailment mechanism are proposed. The theoretical wheelset model is verified by dynamic simulation and its applicability is demonstrated by comparing the simulation results of the theoretical wheelset model with those of an actual wheelset model. The theoretical derailment wheelset model is in good agreement with the virtual testing model simulation for a collision-induced derailment of rolling stock. 相似文献
993.
Hidong Kim Otgonbayar Dugerjav Ganbat Duvjir Huiting Li Seunghun Jang Moonsup Han B.D. Yu Jae M. Seo 《Surface science》2012,606(3-4):312-319
Combined investigation of STM, high-resolution synchrotron photoemission, and density functional theory calculations allowed us to understand the Sb-induced structural-transformation of Si(114)-2 × 1. When 2 ML of Sb is deposited on Si(114)-2 × 1 at room temperature and postannealed at 500 °C, all of the surface Si atoms with dangling bonds are replaced by Sb atoms. Among one-dimensional (1D) structures consisting of Si(114)-2 × 1, such as a dimer with a 6-membered ring (D6) row, a rebonded-atom (R) row, and a tetramer (T) row [D6-R-T], the T row is split into a dimer row with a 7-membered ring (D7) and an R row [D6-R-D7-R]. Since the R-D7-R unit, a building block of Sb/Si(113)2 × 2, is under stress-balance, the Sb/Si(114)-2 × 1 surface is stressed compressively due to the extra D6 unit. As a result, with additional postannealing at 600 °C, two periods of this 2 × 1 [(D6-R-D7-R)-(D6-R-D7-R)] are gradually converted to 2 × 2 [(D6-R-D6-R)-(R-D7-R)], where the D6-R (115) unit is stress-balanced. The corresponding photoemission data obtained from both of the phases show that all of the surface components of the clean surface have disappeared, instead the single Sb–Si interfacial component has appeared, which indicates that the charge transfers from interfacial Si to surface Sb atoms. Finally, the density functional theory calculations have also confirmed that there are two distinct phases determined by the chemical potential of passivating Sb atoms. 相似文献
994.
A rapid and novel ultra-HPLC (u-HPLC) method for the determination of vitamins A (retinol) and E (alpha-, gamma-, and delta-tocopherol) in foods was validated in terms of its precision, accuracy, and linearity. The u-HPLC separation was performed on an RP C18 column (particle size 2 microm, id 2 mm, and length 75 mm), followed by fluorescence detection. The recovery of retinol was more than 84.58%; the LOD and LOQ of the u-HPLC analysis were 0.015 and 0.045 mg/kg, respectively. The intraday and interday precision was less than 9.12%. The recoveries of alpha-, gamma-, and delta-tocopherol were more than 81.37%; the LOD and the LOQ were 0.014, 0.002, and 0.001 mg/kg and 0.042, 0.005, and 0.004 mg/kg, respectively. All calibration curves had good linearity (r2 = 0.99) within the test ranges. The novel, rapid method coupled to u-HPLC can provide significant improvements in the speed, sensitivity, and resolution compared with a conventional HPLC method. 相似文献
995.
Ok-Won Seo Jung Hwan Kim Kwang-Soon Lee Kyu-Sun Lee Ji-Hee Kim Moo-Ho Won Kwon-Soo Ha Young-Guen Kwon Young-Myeong Kim 《Experimental & molecular medicine》2012,44(11):653-664
This study was designed to investigate the effects of the prenylated flavonoid kurarinone on TNF-related apoptosis inducing ligand (TRAIL)-induced apoptosis and its underlying mechanism. A low dose of kurarinone had no significant effect on apoptosis, but this compound markedly promoted tumor cell death through elevation of Bid cleavage, cytochrome c release and caspase activation in HeLa cells treated with TRAIL. Caspase inhibitors inhibited kurarinone-mediated cell death, which indicates that the cytotoxic effect of this compound is mediated by caspase-dependent apoptosis. The cytotoxic effect of kurarinone was not associated with expression levels of Bcl-2 and IAP family proteins, such as Bcl-2, Bcl-xL, Bid, Bad, Bax, XIAP, cIAP-1 and cIAP-2. In addition, this compound did not regulate the death-inducing receptors DR4 and DR5. On the other hand, kurarinone significantly inhibited TRAIL-induced IKK activation, IκB degradation and nuclear translocation of NF-κB, as well as effectively suppressed cellular FLICE-inhibitory protein long form (cFLIPL) expression. The synergistic effects of kurarinone on TRAIL-induced apoptosis were mimicked when kurarinone was replaced by the NF-κB inhibitor withaferin A or following siRNA-mediated knockdown of cFLIPL. Moreover, cFLIP overexpression effectively antagonized kurarinone-mediated TRAIL sensitization. These data suggest that kurarinone sensitizes TRAIL-induced tumor cell apoptosis via suppression of NF-κB-dependent cFLIP expression, indicating that this compound can be used as an anti-tumor agent in combination with TRAIL. 相似文献
996.
Eom MS Jang W Lee YS Choi G Kwon YU Han MS 《Chemical communications (Cambridge, England)》2012,48(45):5566-5568
In this study, the use of bi-ligand co-functionalized gold nanoparticles in a highly selective and sensitive colorimetric probe for Ca(2+) ions is demonstrated and this probe also determined the concentrations of Ca(2+) ions in serum samples. 相似文献
997.
A new approach to protodecarboxylation is described that enhances the substrate scope for benzoic acids. The reaction uses oxidative radical conditions to decarboxylate a variety of acids in acetonitrile. 相似文献
998.
Kang do H Jung HS Ahn N Lee J Seo S Suh KY Kim J Kim K 《Chemical communications (Cambridge, England)》2012,48(43):5313-5315
We rationally designed highly sensitive and selective polydiacetylene (PDA)-phospholipids liposomes for the facile detection of aminoglycosidic antibiotics. The detecting mechanism mimics the cellular membrane interactions between neomycin and phosphatidylinositol-4,5-bisphosphate (PIP(2)) phospholipids. The developed PDA-PIP(2) sensory system showed a detection limit of 61 ppb for neomycin and was very specific to aminoglycosidic antibodies only. 相似文献
999.
Keomkyo Seo 《Monatshefte für Mathematik》2012,166(3-4):525-542
In this paper, we provide various Sobolev-type inequalities for smooth nonnegative functions with compact support on a submanifold with variable mean curvature in a Riemannian manifold whose sectional curvature is bounded above by a constant. We further obtain the corresponding linear isoperimetric inequalities involving mean curvature. We also provide various first Dirichlet eigenvalue estimates for submanifolds with bounded mean curvature. 相似文献
1000.
Byeong-Yun Oh Jeong-Hwan KimJin-Woo Han Dae-Shik Seo Hwan Soo JangHo-Jin Choi Seong-Ho BaekJae Hyun Kim Gi-Seok HeoTae-Won Kim Kwang-Young Kim 《Current Applied Physics》2012,12(1):273-279
Structural, electrical, and optical properties of atomic layer-controlled Al-doped ZnO (ZnO:Al) films grown by atomic layer deposition (ALD) on glass substrates were characterized at various growth temperatures for use as transparent electrodes. The Al atomic content in ZnO:Al films increased due to the reduced ZnO film growth rate with increasing temperature. The preferred orientation of ZnO:Al films was changed, and the optimum condition for best crystallinity was identified by varying the growth temperature. Furthermore, the carrier concentration of free electron was increased by substituting the Zn sites with Al atoms in the crystal, resulting from monolayer growth based on alternate self-limiting surface chemical reactions. The electrical resistivity of ZnO:Al film grown by ALD at 225 °C reached the lowest value of 8.45 × 10−4 Ω cm, with a carrier mobility of 9.00 cm2 V−1 s−1 and optical transmittance of ∼93%. This result demonstrates that ZnO:Al films grown by ALD possess excellent potential for applications in electronic devices and displays as transparent electrodes and surface passivation layers. 相似文献