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1.
Zhen Yan Sivadinarayana Chinta Ahmed A. Mohamed John P. Fackler Jr. D. Wayne Goodman 《Catalysis Letters》2006,111(1-2):15-18
A series of Au/TiO2 catalysts has been prepared from precursors of various metal-organic gold complexes (Au
n
, n = 2–4) and their catalytic activity for CO oxidation studied. The Au/TiO2 catalyst synthesized from a tetranuclear gold complex shows the best performance for CO oxidation with transmission electron
microscopy of this catalyst indicating an average gold particle size of 3.1 nm. 相似文献
2.
Supported gold catalysis in the hydrogenation of canola oil 总被引:1,自引:0,他引:1
L. Caceres L. L. Diosady W. F. Graydon L. J. Rubin 《Journal of the American Oil Chemists' Society》1985,62(5):906-910
The catalytic activity of gold supported on silica orγ-alumina has been studied in the hydrogenation of canola oil. In the hydrogenation of butadiene and pentene using these catalysts,
high stability, low yield oftrans-isomers and high monoene selectivity have been reported in the literature.
Catalysts containing 1% and 5% Au w/w on porous silica andγ-alumina were active in hydrogenating canola oil in the range of 150 to 250 C and 3550 to 5620 kPa. The activity level of
these catalysts was about 30 times lower than that shown by the standard AOCS Ni catalyst based on the concentration of metal
(g Au/L oil). Up to 91% monoene content was obtained using these catalysts in comparison with a maximum of 73% for the AOCS
standard Ni catalysts. Gold catalysts can be recovered easily by filtration and reused several times without a decrease in
activity. The hydrogenated oil was nearly colorless. No gold was detectable in the oil. Contrary to claims in the patent literature,
the gold catalyst produces higher concentrations oftrans-isomers than does nickel. However, using gold catalysts the complete reduction of linolenic acid in canola oil can be achieved
at a lowertrans-isomer content in the products than that obtained by using the AOCS standard nickel catalyst. 相似文献
3.
The electrodeposition of copper from industrial sulphate electrolytes has been studied using electrochemical impedance spectroscopy
on the gold disc ultramicroelectrode. The influence of dc potential E
dc
, temperature, cupric ions and animal glue concentration on electrochemical impedances has been investigated. The mechanism
of the copper electro-reduction process in industrial electrolytes has been proposed and experimental impedance data have
been analyzed by proper equivalent circuits. According to our knowledge the faradaic and non-faradaic impedance parameters
of the process on ultramicroelectrode’s have been estimated for the first time in complex matrix copper industrial electrolytes.
The role of animal glue in copper industrial electrolytes has been discussed in the present paper. 相似文献
4.
Özlem A. Kalaycı Füsun B. Cömert Baki Hazer Turgay Atalay Kevin A. Cavicchi Mukerrem Cakmak 《Polymer Bulletin》2010,65(3):215-226
The synthesis, spectroscopic characterization, and antimicrobial efficiency of gold and silver nanoparticles embedded in novel
amphiphilic comb-type graft copolymers having good film-forming properties have been described. Amphiphilic comb-type graft
copolymers were synthesized by the reaction of chlorinated polypropylene (PP) (M
w = 140,000 Da) with polyethylene glycol (PEG) (M
n
= 2,000 Da) at different molar ratios. Metal nanoparticles embedded graft copolymers were prepared by reducing solutions
of the salts of silver or gold and the copolymer in tetrahydrofuran. The optical properties of the metal nanoparticle embedded
copolymers were determined by using UV–visible spectroscopy. Surface plasmon resonance (SPR) of the gold and silver nanoparticle
embedded copolymers in toluene was observed at a maximum wavelength (λmax) of 428 and 551 nm in the UV–VIS absorption spectra, respectively. The average particle diameters of the gold and silver
nanoparticles were found to be 50 nm from the high resolution scanning electron microscopy (SEM) and energy dispersive X-ray
spectroscopy (EDS). Amphiphilic polymer films containing silver and gold nanoparticles were found to be highly antimicrobial
by virtue of their antiseptic properties to Escherichia coli and Staphylococcus aureus. 相似文献
5.
Recent advances in the biochemistry and clinical relevance of the isoprostane pathway 总被引:2,自引:2,他引:0
Isoprostanes (IsoPs), lipid peroxidation products formed via the free radical-mediated oxidation of arachidonic acid, have become the “gold standard” biomarker of oxidative stress in vivo over the past 15 yr. Significant advances have been made in understanding this important pathway of lipid peroxidation. Recent
studies from our laboratory are discussed that have provided insights into the mechanism of formation and regioisomeric distribution
of these compounds and that have identified novel products of the IsoP pathway such as cyclized dioxolane IsoPs, IsoP-derived
racemic prostaglandins, and reactive cyclopentenone IsoP, the latter of which possess potent biological actions. Furthermore,
new independent studies have demonstrated that IsoPs are the most reliable available marker of lipid peroxidation in vivo, and recent work examining IsoP formation has provided valuable infromation about the pathogenesis of numerous human diseases.
Thus, the complexity of the IsoP pathway has expanded, providing novel insights into mechanisms of lipid peroxidation in vivo and allowing investigators to explore the role of oxidative stress in human disease. 相似文献
6.
Jiadong Huang Xiuming Zhang Su Liu Qing Lin Xiaorui He Xianrong Xing Wenjing Lian 《Journal of Applied Electrochemistry》2011,41(11):1323-1328
A novel bisphenol A (BPA) sensor based on amperometric detection has been developed by using molecularly imprinted polymers
(MIPs) and gold nanoparticles. The sensitive layer was prepared by electropolymerization of 2-aminothiophenol on a gold nanoparticles-modified
glassy carbon electrode in the presence of BPA as a template. Cyclic voltammetry was used to monitor the process of electropolymerization.
The properties of the layer were studied in the presence of Fe(CN)6
3−/Fe(CN)6
4− redox couples. The template and the non-binding molecules were removed by washing with H2SO4 (0.65 mol L−1) solution. The linear response range of the sensor was between 8.0 × 10−6–6.0 × 10−2 mol L−1, with a detection limit of 1.38 × 10−7 mol L−1 (S/N = 3). The proposed MIPs sensor exhibited good selectivity for BPA. The stability and repeatability of the MIPs senor were
found to be satisfactory. The results from real sample analysis confirmed the applicability of the MIPs sensor to quantitative
analysis. 相似文献
7.
Jian Wang Qinling Sheng Na Tian Liyu Chen Ziqin Xu Jianbin Zheng 《Journal of Applied Electrochemistry》2009,39(6):935-945
A novel DNA electrochemical biosensor is described for the detection of neomycin phosphotransferase gene (NPT-II), a selection marker for transgenic plants. A thiol-modified capture probe immobilized onto the surface of a gold electrode
and a biotinylated signaling probe were designed to be complementary to target regions of NPT-II flanked by PCR primers to eliminate false-positive signals from non-specific PCR products. The electrochemical assay of hybrids
on the electrode surface was evaluated by means of both cyclic voltammetry (CV) and square wave voltammetry (SWV) after the coupling of biotinylated catalase with streptavidin-modified hybrids based on dendritic signal magnification and
subsequent formation of polymerized aniline (PAn). It has been revealed that the sensor showed a linear increase within the
target concentration (1.0–100 × 10−6 mmol L−1). The limit of detection was about 0.2 × 10−6 mmol L−1 and the specificity was enhanced significantly. 相似文献
8.
Electrochemical simultaneous determination of nitrophenol isomers at nano-gold modified glassy carbon electrode 总被引:1,自引:1,他引:0
A novel method for simultaneous determination of nitrophenol isomers at nano-gold modified glassy carbon electrode has been
developed. The gold nanoparticles were directly electrodeposited onto the glassy carbon electrode via a constant potential
−0.2 V (vs. SCE) for 60 s from 0.1 mol L−1 KNO3 containing 0.4 g L−1 HAuCl4. The resulting electrode (nano-Au/GCE) was characterized with scanning electron microscopy (SEM). The electrochemistry response
of nitrophenol isomers at the nano-Au/GCE was studied. The result indicated that o-, m-, and p- nitrophenol are separated entirely at nano-Au/GCE, and a semi-derivative voltammetric technology was adopted to enhance
the determination sensitivity. This modified electrode could be applied to direct simultaneous voltammetric determination
of nitrophenol isomers in water samples without preseparation with higher sensitivity. 相似文献
9.
Abstract
Bulk gold powder (~50 μm) catalyzes the oxidative dehydrogenation of amines to give imines using amine N-oxides (R3N-O) as the oxidant. The reaction of dibenzylamine (PhCH2–NH–CH2Ph) with N-methylmorpholine N-oxide (NMMO) in the presence of gold powder at 60 °C produced N-benzylidenebenzylamine (PhCH=N–CH2Ph) in 96% yield within 24 h. Benzyl alcohol was oxidized by NMMO to benzaldehyde in >60% yield in the presence of gold powder. Although O2 was previously shown to oxidize amines in the presence of bulk gold, it is surprising that gold is also capable of catalyzing the oxidation of amines using amine oxides, which are chemically so different from O2. 相似文献10.
Fabrication of Anti-human Cardiac Troponin I Immunogold Nanorods for Sensing Acute Myocardial Damage
Z. R. Guo C. R. Gu X. Fan Z. P. Bian H. F. Wu D. Yang N. Gu J. N. Zhang 《Nanoscale research letters》2009,4(12):1428-1433
A facile, rapid, solution-phase method of detecting human cardiac troponin I for sensing myocardial damage has been described
using gold nanorods-based biosensors. The sensing is demonstrated by the distinct change of the longitudinal surface plasmon
resonance wavelength of the gold nanorods to specific antibody–antigen binding events. For a higher sensitivity, the aspect
ratio of gold nanorods is increased up to ca 5.5 by simply adding small amount of HCl in seed-mediated growth solution. Experimental
results show that the detecting limit of the present method is 10 ng/mL. Contrast tests reveal that these gold nanorods-based
plasmonic biosensors hold much higher sensitivity than that of conventionally spherical gold nanoparticles. 相似文献
11.
Melina Roana de Oliveira Hansen Morten Madsen Jakob Kjelstrup-Hansen Horst-Günter Rubahn 《Nanoscale research letters》2011,6(1):11
Organic nanostructures made from organic molecules such as para-hexaphenylene (p-6P) could form nanoscale components in future electronic and optoelectronic devices. However, the integration of such fragile
nanostructures with the necessary interface circuitry such as metal electrodes for electrical connection continues to be a
significant hindrance toward their large-scale implementation. Here, we demonstrate in situ–directed growth of such organic
nanostructures between pre-fabricated contacts, which are source–drain gold electrodes on a transistor platform (bottom-gate)
on silicon dioxide patterned by a combination of optical lithography and electron beam lithography. The dimensions of the
gold electrodes strongly influence the morphology of the resulting structures leading to notably different electrical properties.
The ability to control such nanofiber or nanoflake growth opens the possibility for large-scale optoelectronic device fabrication. 相似文献
12.
Herein, the generation of gold, silver, and silver–gold (Ag–Au) bimetallic nanoparticles was carried out in collagen (gelatin)
solution. It first showed that the major ingredient in gelatin polypeptide, glutamic acid, acted as reducing agent to biomimetically
synthesize noble metal nanoparticles at 80°C. The size of nanoparticles can be controlled not only by the mass ratio of gelatin
to gold ion but also by pH of gelatin solution. Interaction between noble-metal nanoparticles and polypeptide has been investigated
by TEM, UV–visible, fluorescence spectroscopy, and HNMR. This study testified that the degradation of gelatin protein could
not alter the morphology of nanoparticles, but it made nanoparticles aggregated clusters array (opposing three-dimensional
α-helix folding structure) into isolated nanoparticles stabilized by gelatin residues. This is a promising merit of gelatin
to apply in the synthesis of nanoparticles. Therefore, gelatin protein is an excellent template for biomimetic synthesis of
noble metal/bimetallic nanoparticle growth to form nanometer-sized device. 相似文献
13.
G. L. Burygin B. N. Khlebtsov A. N. Shantrokha L. A. Dykman V. A. Bogatyrev N. G. Khlebtsov 《Nanoscale research letters》2009,4(8):794-801
The bacterial action of gentamicin and that of a mixture of gentamicin and 15-nm colloidal-gold particles on Escherichia coli K12 was examined by the agar-well-diffusion method, enumeration of colony-forming units, and turbidimetry. Addition of gentamicin
to colloidal gold changed the gold color and extinction spectrum. Within the experimental errors, there were no significant
differences in antibacterial activity between pure gentamicin and its mixture with gold nanoparticles (NPs). Atomic absorption
spectroscopy showed that upon application of the gentamicin-particle mixture, there were no gold NPs in the zone of bacterial-growth
suppression in agar. Yet, free NPs diffused into the agar. These facts are in conflict with the earlier findings indicating
an enhancement of the bacterial activity of similar gentamicin–gold nanoparticle mixtures. The possible causes for these discrepancies
are discussed, and the suggestion is made that a necessary condition for enhancement of antibacterial activity is the preparation
of stable conjugates of NPs coated with the antibiotic molecules. 相似文献
14.
Tim Liebert Muhammad Ajaz Hussain Muhammad Nawaz Tahir Thomas Heinze 《Polymer Bulletin》2006,57(6):857-863
Summary Novel α-lipoic acid esters of cellulose (cellulose α-lipoates) were synthesized homogeneously in N,N-dimethylacetamide (DMAc)/LiCl using different methods for the in situ activation of the carboxylic acid. Thus, cellulose α-lipoates with degrees of substitution (DS) in the range 0.11 to 1.45
were accessible with N,N’-carbonyldiimidazole and p-toluenesulphonyl chloride as in situ activating agents for the α-lipoic acid. The reactions proceeded totally homogeneous with high yields giving cellulose α-lipoates
soluble in DMSO. The α-lipoate moiety containing a S-S function stays intact during the reaction as revealed by FTIR and 1H NMR spectroscopy. The cellulose α-lipoates showed self-assembly onto gold surface yielding layers with a thickness of 2.9–4.9 nm,
which can be confirmed by surface plasmon resonance. The perpropionylated cellulose α-lipoates form films with a comparably
low thickness of 0.9 nm. 相似文献
15.
A fine porous gold catalyst has been fabricated by selective leaching of Cu from an ordered AuCu3 intermetallic compound with 50%HNO3 aqueous solution at 50 °C. This catalyst exhibited comparable areal rate (mol min−1 m−2-cat) with the Au/TiO2 catalyst for CO oxidation. The present study demonstrates that high catalytic activity of gold is originated neither from
the presence of fine dispersed Au particles nor from Au-support perimeter interface. 相似文献
16.
S. Vinod Selvaganesh J. Mathiyarasu K. L. N. Phani V. Yegnaraman 《Nanoscale research letters》2007,2(11):546-549
In this work, gold-incorporated polyethylenedioxythiophene nanocomposite material has been synthesized chemically, employing
reverse emulsion polymerization method. Infrared and Raman spectroscopic studies revealed that the polymerization of ethylenedioxythiophene
leads to the formation of polymer polyethylenedioxythiophene incorporating gold nanoparticles. Scanning electron microscope
studies showed the formation of polymer nanorods of 50–100 nm diameter and the X-ray diffraction analysis clearly indicates
the presence of gold nanoparticles of 50 nm in size. 相似文献
17.
Anthony D. Smith Raymond J. Hunt 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(2):110-116
Chromobacterium violaceum, a cyanogenic bacterium, has been shown to solubilise up to 215 parts × 10?6 gold from 1000 parts × 10?6 of the pure metal after 40 days incubation in nutrient medium. Cyanide is produced during the growth and stationary phase of culture and the solubilised gold species has been shown to be the complex anion [Au(CN)2]?. 相似文献
18.
Adsorption of palladium, platinum, and gold chloride complexes by carbon fibers with various structures 总被引:1,自引:0,他引:1
S. A. Simanova A. V. Shukarev A. A. Lysenko S. F. Grebennikov O. V. Astashkina 《Fibre Chemistry》2008,40(4):365-375
Data are given characterizing the effects of the porous structures in activated carbon fibers (ACF) and the amounts of oxidized
carbon forms on the extent and rate of adsorption for various chloride complexes of the platinum metals and gold. The adsorption
mechanisms on ACF are considered for these metal chloride complexes. The practical significance of the research is considered.
Translated from Khimicheskie Volokna, No. 4, pp. 61–69, July–August, 2008. 相似文献
19.
Ken-Tye Yong Yudhisthira Sahoo Mark T. Swihart Paul M. Schneeberger Paras N. Prasad 《Topics in Catalysis》2008,47(1-2):49-60
Seeded growth of gold nanorods (NRs) has been accomplished in a micellar medium containing mixed surfactants or a high salt
concentration. Cetyl trimethylamoniumbromide (CTAB) forms micelles upon which the growth of rod shaped gold nanoparticles
occurs. AgNO3 is introduced into the growth solution to enhance the formation of NRs. The roles of non-ionic surfactants such as Tween
and Triton, and of electrolytes such as sodium chloride and potassium chloride have been examined. As the concentration of
these additives in the growth solution is increased, the aspect ratio of the NRs increases to a critical limit, after which
it decreases again. Upon carefully controlling the content of Triton X-100 or Tween 20 in the growth solution, these non-ionic
surfactants assisted in fine-tuning the shape of gold NRs (e.g. rectangular or “dogbone”). The growth pattern of the NRs fits
into the model of a soft template formed by the mixture of CTAB and non-ionic surfactants. 相似文献
20.
G. A. Sycheva 《Glass Physics and Chemistry》2009,35(6):602-612
The crystal nucleation in the glass of composition (mol %) 26Li2O · 74SiO2 has been investigated in the cases of homogeneous and heterogeneous nucleation. Parameters of homogeneous nucleation, such
as the stationary nucleation rate I
st, the time of nonstationary nucleation τ, and the crystal growth rate U, have been determined. The temperature dependences of these parameters have been constructed. The surface energy σ at the
nucleus-glass melt interface has been determined, and its temperature dependence has been obtained. The surface energy σ has
been evaluated using the graphical method for solving the transcendental equation derived by transforming the relationships
for the stationary crystal nucleation rate and the time of nonstationary crystal nucleation. The critical nucleus sizes r* and the free energy of formation of the critical nucleus Φ* have been determined. The heterogeneous nucleation on bubbles
specially produced in the glass has been studied. It has been demonstrated that the presence of bubbles in the initial glass
does not affect the crystal growth rate and substantially changes the nonstationary nucleation rate. The largest contribution
to the change in the nucleation rate is made by “active” bubbles (filled by water vapor) formed in the glasses synthesized
with the use of hydrated silicon dioxide. 相似文献