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51.
The adsorption characteristics of 1,3‐benzenedithiol (1,3‐BDT) and 1,3‐benzenedimethanethiol (1,3‐BDMT) on Au surfaces are investigated by means of surface‐enhanced Raman scattering, UV/Vis absorption spectroscopy, and cyclic voltammetry (CV). 1,3‐BDMT is found to adsorb via two S–Au linkages at concentrations below monolayer coverage, but to have an upright geometry as the concentration increases on Au nanoparticles. On the other hand, 1,3‐BDT is found to adsorb by forming two S–Au linkages, regardless of concentration, based on the disappearance of the ν(SH)free stretching band. Because of the absence of the methylene unit, 1,3‐BDT appeares not to self‐assemble efficiently on Au surfaces. The UV/Vis absorption spectroscopy and CV techniques are also applied to check the formation of self‐assembled monolayers of 1,3‐BDT and 1,3‐BDMT on Au. Density functional theory calculations based on a simple adsorption model using an Au8 cluster are performed to better understand the nature of the adsorption characteristics of 1,3‐BDT and 1,3‐BDMT on Au surfaces. 相似文献
52.
Kim HM Jeong BH Hyon JY An MJ Seo MS Hong JH Lee KJ Kim CH Joo T Hong SC Cho BR 《Journal of the American Chemical Society》2008,130(13):4246-4247
We report a new two-photon fluorescence turn-on probe 6-[(E)-3-oxo-1-dodecenyl]-2-[N-methyl-N-(carboxymethyl)amino]naphthalene (CL2) that is designed specifically for visualizing lipid rafts in living cells and tissues. This probe emits much brighter two-photon excited fluorescence in lipid rafts than in non-raft domains and allows direct visualization of the lipid rafts in the live cells and pyramidal neuron layer of the CA1 region at a depth of 100-250 mum in live tissues using two-photon microscopy. 相似文献
53.
A tandem time-of-flight mass spectrometer for the study of photodissociation of biopolymer ions generated by matrix-assisted laser desorption ionization was designed and constructed. A reflectron with linear and quadratic (LPQ) potential components was used. Characteristics of the LPQ reflectron and its utility as the second stage analyzer of the tandem mass spectrometer were investigated. Performance of the instrument was tested by observing photodissociation of [M + H](+) from angiotensin II, a prototype polypeptide. Quality of the photodissociation tandem mass spectrum was almost comparable to that of the post-source decay spectrum. Monoisotopic selection of the parent ion was possible, which was achieved through the ion beam-laser beam synchronization. General theoretical considerations needed for a successful photodissociation of large biopolymer ions are also presented. 相似文献
54.
Nishat Arshi Junqing Lu Yun Kon Joo Jae Hong Yoon Bon Heun Koo 《Surface and interface analysis : SIA》2015,47(1):154-160
Nanocrystalline tantalum nitride (TaN) thin films have been deposited by reactive direct current magnetron sputtering technique on Si/SiO2 (100) substrate with nitrogen flow rate ranging from 0, 3, 5, 7, 9 to 11 standard cubic centimeter per minute (sccm). Structural properties, surface morphology, chemical composition and and resistivity of the TaN films were investigated by X‐ray diffraction (XRD), field emission scanning electron microscopy, X‐ray photoemission spectroscopy (XPS) and four‐point probe measurements, respectively. In the XRD spectra, a classical formation sequence of tantalum nitride phases in the order of Ta‐Ta2N‐TaN‐Ta4N5 and decreasing amount of metallic Ta were observed with increasing nitrogen flow. The electrical resistivity of the TaN film was found to increase with increasing N/Ta ratio as a result of the increased electron scattering from interstitial N atoms. In the XPS analysis, two groups of Ta4f doublets relating to different TaN phases were observed in the core level spectra of TaN films. No strong coupling was observed between the Ta4f doublets and the Ta4p and the N1s groups. The appropriate nitrogen flow was believed to be helpful in the bonding and formation of stoichiometric TaN. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
55.
Hyeong Jin Yun Hyunjoo Lee Ji Bong Joo Nam Dong Kim Jongheop Yi 《Electrochemistry communications》2010,12(6):769-772
We describe a method tuning the band-gap energy (Eg) of visible light sensitive TiO2-xCx nanoparticle. Eg tends to become smaller with the increase in the amount of carbon dopant in TiO2-xCx nanoparticle due to the increase in excess electrons. Photo-catalytic oxidative activity, however, did not depend on only the value of Eg, but also the energy level of valence band. TiO1.96C0.04 nanoparticle having Eg of 2.6 eV showed outstanding performance in oxidative decomposition of phenol under the irradiation of visible light. 相似文献
56.
Heo SK Ju SA Kim GY Park SM Back SH Park NH Min YJ An WG Nguyen TT Kim SM Kim BS 《Experimental & molecular medicine》2012,44(2):149-158
The development of gastric cancer (GC) is closely related to chronic inflammation caused by Helicobacter pylori infection, and herpes virus entry mediator (HVEM) is a receptor expressed on the surface of leukocytes that mediates potent inflammatory responses in animal models. However, the role of HVEM in human GC has not been studied. Previously, we showed that the interaction of HVEM on human leukocytes with its ligand LIGHT induces intracellular calcium mobilization, which results in inflammatory responses including induction of proinflammatory cytokine production and anti-bacterial activities. In this study, we report that leukocytes from GC patients express lower levels of membrane HVEM (mHVEM) and have lower LIGHT-induced bactericidal activities than those from healthy controls (HC). In contrast, levels of soluble HVEM (sHVEM) in the sera of GC patients were significantly higher than in those of HC. We found that monocyte membrane-bound HVEM is released into the medium when cells are activated by proinflammatory cytokines such as TNF-α and IL-8, which are elevated in the sera of GC patients. mHVEM level dropped in parallel with the release of sHVEM, and release was completely blocked by the metalloprotease inhibitor, GM6001. We also found that the low level of mHVEM on GC patient leukocytes was correlated with low LIGHT-induced bactericidal activities against H. pylori and S. aureus and production of reactive oxygen species. Our results indicate that mHVEM on leukocytes and sHVEM in sera may contribute to the development and/or progression of GC. 相似文献
57.
58.
Hyun Joo Rhee 《Tetrahedron letters》2004,45(43):8019-8022
Stereoselective synthesis of (+)-lauthisan has been accomplished starting from d-glyceraldehyde acetonide by combination of diastereoselective alkylation and ring-closing metathesis. High degree of 1,3-asymmetric induction has been realized in ether system. 相似文献
59.
Supercritical fluid extraction (SFE) of the fluoroquinolones norfloxacin and ofloxacin from chicken breast muscles was examined. A liquid chromatography with fluorescence detection was used for the determination of the fluoroquinolones. Extraction conditions of the SFE were optimized by determining the extraction parameters to achieve a sufficiently high recovery of each fluoroquinolone in fortified-muscle samples. Recovery values for the extraction of the fluoroquinolones using the SFE ranged from 70 to 87%. Chickens were treated orally with each fluoroquinolone and their muscles were extracted at set time intervals for time-course determination of the fluoroquinolones in chickens. The SFE combined with liquid chromatographic analysis showed that the concentrations of the fluoroquinolones decreased gradually with time in the chicken muscles after oral treatment, giving a concentration less than 5 ng/ml in 120 h. No further sample cleanup procedures were required after the SFE. These results suggest that SFE method is an extraction method for the determination of norfloxacin and ofloxacin in chicken muscle. 相似文献
60.
Young‐Hyuk Joo Dr. Jean'ne M. Shreeve Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(13):3198-3203
High energy density materials with ethylene‐ and propylene bis(5‐nitroiminotetrazolate) as the anions are reported; all salts were fully characterized by IR, and 1H, 13C, and 15N NMR spectroscopy as well as elemental analyses. In addition, the heats of formation (ΔHf) and the detonation pressures (P) and velocities (D) were calculated.