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Direct Deposition (direct + deposition)
Selected AbstractsElectronic gel protein transfer and identification using matrix-assisted laser desorption/ionization-mass spectrometryELECTROPHORESIS, Issue 9 2004Jonathan W. Cooper Abstract An electronic protein transfer technique is described for achieving the rapid and efficient recovery of sodium dodecyl sulfate (SDS)-protein complexes from polyacrylamide gels. This process involves the use of small-dimension capillaries in physical contact with a resolved protein band within the polyacrylamide gel, providing a large potential drop and high electric field strength at the capillary/gel interface. Several factors controlling the electronic protein transfer, including the applied electric field strength, the electrophoresis buffer concentration, and the capillary dimension, are studied to further enhance the use of field-amplification for sample stacking of extracted SDS-protein complexes. As a result of sample stacking, the extracted proteins from a 50 ng gel loading are present in a narrow (,80 nL) and highly concentrated (0.46 mg/mL or 3.3×10,5 M for cytochrome c) solution plug. Three model proteins with molecular mass ranging from 14 kDa (cytochrome c) to 116 kDa (,-galactosidase) are stained by Coomassie blue and electrophoretically extracted from gels with protein loadings as low as 50 ng. The capillary format of the electronic protein transfer technique allows direct deposition of extracted proteins onto a matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) target. Various matrices and solvent compositions are evaluated for the analysis of extracted and concentrated SDS-protein complexes using MALDI-MS. The electronic protein transfer technique, when operated under optimized conditions, is demonstrated for the effective (>70% recovery), speedy (less than 5 min), and sensitive MS identification of gel resolved proteins (as low as 50 ng). [source] A comparison of EDI with solvent-free MALDI and LDI for the analysis of organic pigmentsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2008Ichiro Kudaka Abstract To evaluate the applicability of EDI to material analysis as a new ionization method, a comparison of EDI with solvent-free matrix-assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) was made for the analysis of organic pigments, e.g. Pigment Yellow 93, Pigment Yellow 180, and Pigment Green 36, as test samples, which are poorly soluble in standard solvents. In EDI, the samples were prepared in two ways: deposition of suspended samples in appropriate solvents and dried on the substrate, and the direct deposition of the powder samples on the substrate. No matrices were used. Both sample preparation methods gave similar mass spectra. Equally strong signals of [M + H]+ and [M , H], ions were observed with some fragment ions for azo pigments in the respective positive or negative mode of operation. For the powder sample of the phthalocyanine pigment PG36, M+, and [M + H]+ in the positive mode and M,, in the negative mode of operation were observed as major ions. Positive-mode, solvent-free MALDI gave M+, [M + H]+ and [M + Na]+ and negative mode gave [M , H], depending on the sample preparation. As solvent-free MALDI, EDI was also found to be an easy-to-operate, versatile method for the samples as received. Copyright © 2008 John Wiley & Sons, Ltd. [source] The effect of low pressure chemical vapor deposition of silicon nitride on the electronic interface properties of oxidized silicon wafersPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2007Hao Jin Abstract The effect of LPCVD Si3N4 film deposition on oxidized Si wafers, to form Si3N4/SiO2/Si stacks, is studied using capacitance,voltage and carrier lifetime measurements. The deposition of a nitride film leads to an increase in the density of defects at the Si,SiO2 interface, with the increase being greater the thinner the oxide. However, even the presence of a very thin intermediate oxide results in a dramatic improvement in interface properties compared to the direct deposition of the Si3N4 film on Si. The interface degradation occurs in the initial stages of nitride film deposition and appears to be largely the result of increased interfacial stress. Subsequent thermal treatments do not result in significant further degradation of the Si,SiO2 interface (except for a loss of hydrogen), again in contrast to the case where the nitride films is deposited onto Si. Copyright © 2007 John Wiley & Sons, Ltd. [source] Photoelectrochemical Behavior of Nanostructured WO3 Thin-Film Electrodes: The Oxidation of Formic AcidCHEMPHYSCHEM, Issue 12 2006Damián Monllor-Satoca Abstract Nanostructured tungsten trioxide thin-film electrodes are prepared on conducting glass substrates by either potentiostatic electrodeposition from aqueous solutions of peroxotungstic acid or direct deposition of WO3 slurries. Once treated thermally in air at 450,°C, the electrodes are found to be composed of monoclinic WO3 grains with a particle size around 30,40 nm. The photoelectrochemical behavior of these electrodes in 1,M HClO4 apparently reveals a low degree of electron,hole recombination. Upon addition of formic acid, the electrode showed the current multiplication phenomenon together with a shift of the photocurrent onset potential toward less positive values. Photoelectrochemical experiments devised on the basis of a kinetic model reported recently [I. Mora-Seró, T. Lana-Villarreal, J. Bisquert, A. Pitarch, R. Gómez, P. Salvador, J. Phys. Chem. B2005, 109, 3371] showed that an interfacial mechanism of inelastic, direct hole transfer takes place in the photooxidation of formic acid. This behavior is attributed to the tendency of formic acid molecules to be specifically adsorbed on the WO3 nanoparticles, as evidenced by attenuated total reflection infrared spectroscopy. [source] | ||||||||||