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81.
M. A. Gomez H. Assaaoudi L. Becze J. N. Cutler G. P. Demopoulos 《Journal of Raman spectroscopy : JRS》2010,41(2):212-221
Three crystalline ferric arsenate phases: (1) scorodite; FeAsO4·2H2O, (2) ferric arsenate sub‐hydrate (FAsH; FeAsO4·0.75H2O) and (3) basic ferric arsenate sulfate (BFAS; Fe[(AsO4)1−x(SO4)x(OH)x]·wH2O) synthesized by hydrothermal precipitation (175–225 °C) from Fe(III)‐AsO43−–SO42− solutions have been investigated via Raman and infrared spectroscopies. The spectroscopic nature of these high‐temperature Fe(III)‐ AsO43−–SO42− phases has not been extensively studied despite their importance to the hydrometallurgical industrial processing of precious metal (Au and Cu) arsenic sulfidic ores. It was found that scorodite, FAsH and BFAS all gave rise to very distinct arsenate, sulfate and hydroxyl vibrations. In scorodite and FAsH, the distribution of the internal arsenate modes was found to be distinct, with the factor effect being more predominant in the crystal system. For the crystallographically unknown BFAS phase, vibrational spectroscopy was used to monitor the arsenate ↔ sulfate solid solution behavior that occurs in this phase where the molecular symmetry of arsenate and sulfate in the crystal structure is reduced from an ideal Td to a distorted Td or C2/C2v symmetry. With the new collected vibrational data of the pure phases, the use of attenuated total reflectance infrared (ATR‐IR) spectroscopy was finally extended to investigate the nature of the arsenate in an industrial residue generated by pressure oxidation of a gold ore, where it was found that the arsenate was present in the form of BFAS. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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83.
Silver staining has been the method most commonly employed for high sensitivity staining of proteins following two-dimensional gel electrophoresis. Whilst this method offers detection in the nanogram range it does have major drawbacks including a lack of linearity, nonstoichiometric staining of proteins, a lack of compatibility with the microchemical preparation of proteins for identification by mass spectrometric techniques, and a highly subjective assessment of the staining endpoint. SYPRO Ruby is a relatively new, ruthenium complex-based stain which is reported to offer advantages over silver, particularly in overcoming the limitations cited above. We describe a series of experiments where several protein staining procedures commonly employed are compared. To enable optimization of the in situ digestion procedure, a statistical approach has been undertaken. The effects of a variety of staining, digestion, and analysis protocols on the downstream processing of a test radiolabeled protein were studied. The data confirms that as well as offering sensitivity similar to silver, SYPRO Ruby staining is reproducible, linear, and offers a higher level of compatibility with the identification of proteins by mass spectrometry. 相似文献
84.
Isaacs SR Cutler EC Park JS Lee TR Shon YS 《Langmuir : the ACS journal of surfaces and colloids》2005,21(13):5689-5692
This paper shows that an introduction of thiosulfate anions in place of bromide anions greatly improves both chemical and thermal stability of tetraoctylammonium-protected gold nanoparticles. Tetraoctylammonium thiosulfate [(Oct)4N+-O3SS]-protected gold nanoparticles are synthesized by the reduction of (Oct)4N+-AuCl4 to Au(I)-SSO3-, followed by the addition of sodium borohydride. The presence of thiosulfate anions instead of bromide anions on the surface of gold nanoparticles results in a significant dampening of the surface plasmon band of gold at 526 nm due to the strong interaction between thiosulfate and the gold nanoparticle surface. Cyanide decomposition and heating treatment studies suggest that (Oct)4N+-O3SS-protected nanoparticles have much higher overall stability compared to (Oct)4N+-Br-protected gold nanoparticles. 相似文献
85.
T. E. Sullivan A. A. Lucas P. H. Cutler 《Applied Physics A: Materials Science & Processing》1977,14(3):289-294
In a series of recent experiments, research groups have made absolute frequency measurements with laser beams in the infrared
region (μm) using a metal-metal point contact diode for the generation, frequency mixing and detection. At present there are
two models which attempt to explain the rectification mechanism of the diode: 1) Tunneling of electrons through an intermediate
oxide film from whisker to the metal base, i.e., configuration is considered to be a metal-oxide-metal (MOM) tunneling junction.
2) Rectification and nonlinear processes are the result of a thermal enchanced field emission. Such emission is a consequence
of the immersion of the whisker in the laser radiation which results in conduction induced thermionic emission and/or generation
of an electric field at the tip necessary for electron tunneling by field emission. The purpose of this comment is: a) to
discuss qualitatively the basic difference between MOM and TFE theories as regards the origin of the nonlinearity and rectification
properties of the metal point contact junction; b) to review the analyses describing the ultimate frequency response of the
device; and 3) to provide a possible explanation for polarity reversal consistent with the TFE mechanism describing the operation
of the whisker diode.
This research was supported in part by the NATO Research Grants Program, Scientific Affairs, Brussels, Belgium, and under
the auspices of the joint projects ESIS (electronic structure in solids) and IRIS (Institute for Research in Interface Sciences)
of the Belgian Ministry for Science Policy 相似文献
86.
87.
Cutler A Weber A Smits R Cooper N 《The Journal of the Acoustical Society of America》2004,116(6):3668-3678
Native American English and non-native (Dutch) listeners identified either the consonant or the vowel in all possible American English CV and VC syllables. The syllables were embedded in multispeaker babble at three signal-to-noise ratios (0, 8, and 16 dB). The phoneme identification performance of the non-native listeners was less accurate than that of the native listeners. All listeners were adversely affected by noise. With these isolated syllables, initial segments were harder to identify than final segments. Crucially, the effects of language background and noise did not interact; the performance asymmetry between the native and non-native groups was not significantly different across signal-to-noise ratios. It is concluded that the frequently reported disproportionate difficulty of non-native listening under disadvantageous conditions is not due to a disproportionate increase in phoneme misidentifications. 相似文献
88.
The objective of this research is to describe the formation of foam glass from waste glass using water as a gasifying agent similar to natural perlite. Artificial perlite with up to 10% water content may be made from waste soda-lime glass by subjecting the glass to water vapor under moderate pressures (less than 250°C). The maximum rate of absorption requires a minimum amount of liquid water to be in contact with the glass. Excess liquid water dilutes the corrosion action of alkali formed. Rate of water absorption as a function of water content and 1N NaOH solution content were examined on rods of glass as well as glass powder. Water adsorption was obtained by heating glass compositions in saturated steam in an autoclave. In general, the absorption of water was related to particle size, liquid water content, hydroxide ion concentration and glass composition. 相似文献
89.
N. M. Miskovsky P. H. Cutler T. E. Feuchtwang A. A. Lucas 《International Journal of Infrared and Millimeter Waves》1981,2(4):739-772
Using the Mehler-Fock transformation to solve Poisson's equation in prolate spheroidal coordinates, we have obtained an exact Green's function solution for all multiple image corrections to the vacuum tunneling barrier for a hyperboloidal tip-planar-anode model of a point-contact junction consisting of identical or dissimilar metals.These calculations show that the image corrections significantly modify both the form and area of the barrier, producing an enhancement in the rectification and tunneling currents at low bias.I–V characteristics have also been obtained for the hyperboloidal tip model using estimates of the emission and collection regions based on field emission experiments for whisker tips of comparable dimensions. These results are compared with earlier calculations whichThis research was supported in part by the NATO Research Grants Program, Grant No. 1902, Scientific Affairs Division, Brussels, BELGIUM. 相似文献
90.