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871.
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
872.
873.
Lee SU Khazaei M Pichierri F Kawazoe Y 《Physical chemistry chemical physics : PCCP》2008,10(34):5225-5231
We present a systematic analysis of electron transport characteristics of carbon nanotube (CNT) intramolecular heterojunctions with peptide linkages, MM, SS, SM1, and SM2 where M and S stand for metallic and semiconducting CNT electrodes, respectively. Our theoretical investigations show that the incorporation of peptide linkages and their associated dipole moments play an important role in determining the electron transport characteristics and lead to materials with unique properties, such as Schottky-like behavior. Furthermore, we show that the Schottky-like behavior is observed in our SM1 junction but not in the SM2 junction because of the different effects that arise from both the direction and strength of their dipole moments. We believe that our results will pave the way towards the design and implementation of various electronic logic functions based on carbon nanotubes for applications in the field of nanoelectronics. 相似文献
874.
Oh YJ Gamble TC Leonhardt D Chung CH Brueck SR Ivory CF Lopez GP Petsev DN Han SM 《Lab on a chip》2008,8(2):251-258
Using Si as the substrate, we have fabricated multiple internal reflection infrared waveguides embedded with a parallel array of nanofluidic channels. The channel width is maintained substantially below the mid-infrared wavelength to minimize infrared scattering from the channel structure and to ensure total internal reflection at the channel bottom. A Pyrex slide is anodically bonded to the top of the waveguide to seal the nanochannels, while simultaneously enabling optical access in the visible range from the top. The Si channel bottom and sidewalls are thermally oxidized to provide an electrically insulating barrier, and the Si substrate surrounding the insulating SiO(2) layer is selectively doped to function as a gate. For fluidic field effect transistor (FET) control, a DC potential is applied to the gate to manipulate the surface charge on SiO(2) channel bottom and sidewalls and therefore their zeta-potential. Depending on the polarity and magnitude, the gate potential can accelerate, decelerate, or reverse the flow. Here, we demonstrate that this nanofluidic infrared waveguide can be used to monitor the FET flow control of charged, fluorescent dye molecules during electroosmosis by multiple internal reflection Fourier transform infrared spectroscopy. Laser scanning confocal fluorescence microscopy is simultaneously used to provide a comparison and verification of the IR analysis. Using the infrared technique, we probe the vibrational modes of dye molecules, as well as those of the solvent. The observed infrared absorbance accounts for the amount of dye molecules advancing or retracting in the nanochannels, as well as adsorbing to and desorbing from the channel bottom and sidewalls. 相似文献
875.
876.
We present a significant sensitivity improvement of interferometric multiplex coherent anti-Stokes Raman scattering (CARS) by optimizing the power, bandwidth and phase of the pump, Stokes, and probe pulses independently. Fourier transform spectral interferometry (FTSI) is used to retrieve the entire complex quantity of the CARS spectrum by utilizing the non-resonant background as a local oscillator. Background-free spontaneous Raman-like vibrational spectra can be measured over the 500-1400 cm(-1) range with 20 cm(-1) spectral resolution within a tens of microseconds time scale. Chemically selective microscopy of a multicomponent polymer film is performed to demonstrate the feasibility of its microscopy application. A systematic analysis of the signal recovery method and several technical issues are discussed. 相似文献
877.
878.
Dong Ryul Park Heesoo Kim Ji Chul Jung Sang Hee Lee Joohyung Lee In Kyu Song 《Reaction Kinetics and Catalysis Letters》2008,93(1):43-49
Vanadium-containing H6+xP2Mo18−xVxO62 (x = 0, 1, 2 and 3) Wells-Dawson heteropolyacid (HPA) and H3+xPMo12−xVxO40 (x = 0, 1, 2 and 3) Keggin HPA catalysts were applied to the vapor-phase dehydrogenation of cyclohexanol. The catalytic oxidation
activity showed a volcano-shaped curve with respect to vanadium substitution for both families of HPA catalysts. The Wells-Dawson
HPA showed a better catalytic oxidation performance than the Keggin HPA at the same level of vanadium substitution. 相似文献
879.
880.
Mohamed E Abdul-Rahman PS Doustjalali SR Chen Y Lim BK Omar SZ Bustam AZ Singh VA Mohd-Taib NA Yip CH Hashim OH 《Electrophoresis》2008,29(12):2645-2650
A 35 kDa glycoprotein whose abundance was previously demonstrated to be enhanced in sera of patients with endometrial adenocarcinoma (n = 12), was isolated from pooled sera of three of the cancer patients using champedak galactose-binding lectin affinity chromatography in the present study. Subjecting it to 2-DE and MS/MS, the glycoprotein was identified as the O-glycosylated fragment of inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4). When compared to control sera (n = 17), expression of the 35 kDa ITIH4 cleavage fragment was demonstrated to be significantly enhanced in sera of patients with breast carcinoma (n = 10), epithelial ovarian carcinoma (n = 10), and germ cell ovarian carcinoma (n = 10) but not in patients with nasopharyngeal carcinoma (n = 13) and osteosarcoma (n = 7). The lectin-based electrophoretic bioanalytical method adopted in the present study may be used to assess the physiological relevance of ITIH4 fragmentation and its correlation with different malignancies, their stages and progression. 相似文献