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1.
ZHOU Guowei KANG Youngsoo LI Tianduo & XU Guiying . School of Light Chemicals Environmental Engineering Shandong Institute of Light Industry Jinan China . Department of Chemistry Pukyong National University Daeyeon--dong Nam-gu Pusan - Korea . Key Laboratory for Colloid Interface of Ministry of Education of China Shandong University Jinan China 《中国科学B辑(英文版)》2005,48(3)
Titanium dioxide (TiO2) is one of the green cata-lysts, which has attracted much attention due to its promising applications in the purification of air, the bactericidal action of water, and environmental photocatalytic degradation of organic pollutant co… 相似文献
2.
The effects of H2 and H2 + O2 gas mixtures of varying composition on the state of the surface of the Pt/MoO3 model catalyst prepared by vacuum deposition of platinum on oxidized molybdenum foil were investigated by X-ray photoelectron spectroscopy (XPS) at room temperature and a pressure of 5–150 Torr. For samples with a large Pt/Mo ratio, the XP spectrum of large platinum particles showed that the effect of hydrogen-containing mixtures on the catalyst was accompanied by the reduction of molybdenum oxide. This effect results from the activation of molecular hydrogen due to the dissociation on platinum particles and subsequent spill-over of hydrogen atoms on the support. The effect was not observed at low platinum contents in the model catalyst (i.e., for small Pt particles). It is assumed for the catalyst that the loss of its hydrogen-activating ability is a consequence of the formation of platinum hydride. Possible participation of platinum hydride as intermediate in hydrogen oxidation to H2O2 is discussed. 相似文献
3.
This investigation examines the magnetorheological (MR) characteristics of Fe3O4 aqueous suspensions. Magnetite particles (Fe3O4) were synthesized using a colloidal process and their sizes were determined to be normally distributed with an average of
10 nm by TEM. Experimental results reveal that the MR effect increases with the magnetic field and suspension concentration.
The yield stress increases by up to two orders of magnitude when the sample is subjected to a magnetic field of 146 Oe/mm.
In comparison with other published results, concerning a concentration of approximately 10–15% v/v, this study demonstrates
that the same increase can be obtained with a concentration of nano-scale particles as low as 0.04% by volume. The viscosity
was increased by an order of magnitude while the shear rate remained low; however, the increase decayed rapidly as the shear
rate was raised. Finally, the MR effect caused by DC outperformed that caused by AC at the same current. 相似文献
4.
A novel amperometric immunosensor was developed by immobilizing ferritin antibody (FeAb) on the surface of Fe3O4 magnetic nanoparticles/chitosan composite film modified glassy carbon electrode (GCE). This material combined the advantages
of inorganic Fe3O4 nanoparticles with the organic polymer chitosan. The stepwise assembly procedure of the immunosensor was characterized by
means of differential pulse voltammetry (DPV) and ac impedance. The K3Fe(CN)6/K4Fe(CN)6 was used as a marker to probe the interface and to determinate ferritin. The factors that could influence the performance
of the resulting immunosensor were studied in detail. After the immunosensor was incubated with ferritin for 32 min at 35 °C,
the DPV current decreased linearly with the logarithm of ferritin concentration in the range from 20 to 500 ng mL−1 with a correlation coefficient of 0.995 and a detection limit of 7.0 ng mL−1. This immunosensor was used to analyze ferritin in human serum samples. The analytical results showed that the developed
immunoassay was comparable with the radioimmunoassay (RIA), and the studied immunosensor exhibited good accuracy, high sensitivity,
and long-term stability for 3 weeks, which implies a promising alternative approach for detecting ferritin in clinical diagnosis. 相似文献
5.
Atomic models are proposed for nanotubes of the titanium silicocarbides Ti2SiC, Ti3SiC2, and Ti4SiC3, and their electronic structure and interatomic interactions are investigated by the density functional tight-binding method
(DFTB) in comparison with the corresponding crystalline phases.
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 2, pp. 88-92, March-April, 2009. 相似文献
6.
The reaction mechanism of (CH3)3CO. radical with NO is theoretically investigated at the B3LYP/6-31G* level. The results show that the reaction is multi-channel
in the single state and triplet state. The potential energy surfaces of reaction paths in the single state are lower than
that in the triple state. The balance reaction: (CH3)3CONO⇔(CH3)3CO.+NO, whose potential energy surface is the lowest in all the reaction paths, makes the probability of measuring (CH3)3CO. radical increase. So NO may be considered as a stabilizing reagent for the (CH3)3CO. radical. 相似文献
7.
Fe3O4/Au composite particles with core/shell structure were prepared by reduction of Au3+ with hydroxylamine in the presence of an excess of Fe3
O4 as seeds. The resultant colloids, with an average diameter of less than 100 nm, were obtained; the remaining non-reacted
Fe3O4 seeds can be removed by treatment with diluted HCl solution. The Fe3O4/Au colloids exhibit a characteristic peak of UV-visible spectra, which largely depend on the size of the particle and the
suspension medium. The localized surface plasmon resonance peaks red shift and broaden with increased nanoparticle diameter
or increased solvent ionic strength. The optical property is very important in the establishment of means for the detection
of biomolecules. 相似文献
8.
Areas of fusion and crystallization peaks of K3TaO2F4 and KTaF6 were measured using the DSC mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering
the temperature dependence of the calorimeter sensitivity, values of the fusion enthalpy of K3TaO2F4 at the fusion temperature of 1181 K of (43 ± 4) kJ mol−1 and of KTaF6 at the fusion temperature of 760 K of (8 ± 1) kJ mol−1 were determined. 相似文献
9.
Yong Hong Wang Yang Zhang Xing Qin Liu Guang Yao Meng 《Journal of Sol-Gel Science and Technology》2007,41(3):267-275
A simple approach namely sol-coated technique has been developed for the low cost fabrication of macroporous ceramic under
a far below common sintering temperature of alumina with large dimension grains. The prepared green support shows higher sinteractive
than the one treated by wet impregnation method under the same sintering conditions. The support possesses great potential
applications with 6.63–7.71 μm in pore size, 39% open porosity as well as >45 MPa mechanical strength at the sintering temperature
range of 1350°– 1500°C. The results indicate that the nitrogen gas flux and pure water permeation value was 51 252.35 m3 m−2 h−1 bar−1, 98.43 m3 m−2 h−1 bar−1, respectively, which were more dependent on the pore structure and pore size distribution than open porosity. 相似文献
10.
Vibrational spectra of finely divided amorphous CsHSO4,Cs5H3(SO4)4 · H2O, and composites based on these are measured and analyzed. An analysis of the spectra indicates the occurrence of substantial changes in the system of hydrogen bonds and in the spectral range of the sulfate group of acid sulfates in the composites. Structural dynamics of the SO4 tetrahedrons is in full conformance with protonic conduction and the data of x-ray diffraction analyses accompanied by differential scanning calorimetry. It is shown that mobility of protons in the composites increases. A mechanism of the formation of the composites and their conduction is proposed.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 640–645.Original Russian Text Copyright © 2005 by Ponomareva, Lavrova, Burgina. 相似文献
11.
The sol-gel processing of lead-free (Na,K) NbO3 ferroelectric films was studied. Sodium ethoxide (NaOC2H5) and potassium ethoxide (KOC2H5) were prepared by reacting solid Na and K with ethanol (99.7%) in a solvent of 2-methoxyethanol. 0.5-μm-thick (Na,K)NbO3 thin films with orthorhombic perovskite structure were obtained by pyrolyzing at 400°C and annealing at 800–900°C. The films
had relatively dense and uniform microstructure with grain size of about 50 nm, whose ferroelectricity was proved by the P-E hysteresis loop measurement. It was found that excess K was effective to reduce the annealing temperature for the crystallization
of sol-gel-derived (Na,K)NbO3 thin films. 相似文献
12.
V. M. Zainullina V. L. Volkov N. V. Podvalnaya A. L. Ivanovskii 《Journal of Structural Chemistry》2005,46(2):340-342
The calculations of the electronic structure of layered polyvanadate K2V3O8 were made employing the spin-polarized tight-binding LMTO method. Calculated magnetic moment for K4V6O16 compound phase equals 1.97 μB. V-O interactions were established to be dominating in the chemical bonding generation in this polyvanadate according to the estimated crystal orbital overlap population. The covalent bonds V(2)-V(2) in V(2)2O7 groups and electron density localization on vanadium atoms in isolated pyramids V(1)O5 were found. 相似文献
13.
Large-scale Li1+x
V3O8 nanobelts were successfully fabricated using filter paper as deposition substrate through a simple surface sol–gel method.
The nanobelts were as long as tens of micrometers with widths of 0.4–1.0 μm and thickness of 50–100 nm. The nanobelts were
characterized by X-ray diffration (XRD), Fourier infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission
electron microscopy (TEM). The formation mechanism of the nanobelts was investigated, showing that the morphology of the nanobelts
is mainly determined by the calcination temperature. Electrochemical properties of the Li1+x
V3O8 nanobelts were characterized by charge–discharge experiments, and the results demonstrate that the Li1+x
V3O8 nanobelts exhibit a high discharge capacity (278 mAh g−1) and excellent cycling stability. 相似文献
14.
N. B. Babanly Yu. A. Yusibov R. J. Mirzoeva Yu. M. Shykhyev M. B. Babanly 《Russian Journal of Electrochemistry》2009,45(4):405-410
The Cu-B-Se (B = In, As, Sb, Bi) systems are studied by measurement of EMF for concentration circuits vs. a copper electrode in the temperature range of 300–430 K. A solid superionic Cu4RbCl3I2 conductor is used as an electrolyte. Diagrams of solid-phase equilibriums in the studied systems are constructed. Partial molar functions of alloyed copper are calculated on the basis of the equations of the temperature dependences of EMF. Potential-forming reactions corresponding to the measured EMF values are determined on the basis of the phase diagrams and standard thermodynamic formation functions and standard entropies of ternary compounds are calculated. 相似文献
15.
The areas of the fusion and crystallization peaks of Na3FeF6 and of four calibration substances (KCl, NaCl, Na2SO4, and K2SO4) were measured using the DSC mode of a high-temperature calorimeter. Using the measured quantities and known values of the
enthalpy of fusion of the calibration substances, the enthalpy of fusion of Na3FeF6 was determined. Its value at the temperature of fusion 1224 K was 70 ± 4 kJ mol−1. 相似文献
16.
2CaO·3B2O3·H2O which has non-linear optical (NLO) property was synthesized under hydrothermal condition and identified by XRD, FTIR and
TG as well as by chemical analysis. The molar enthalpy of solution of 2CaO·3B2O3·H2O in HCl·54.572H2O was determined. From a combination of this result with measured enthalpies of solution of H3BO3 in HCl·54.501H2O and of CaO in (HCl+H3BO3) solution, together with the standard molar enthalpies of formation of CaO(s), H3BO3(s), and H2O(l), the standard molar enthalpy of formation of −(5733.7±5.2) kJ mol−1 of 2CaO·3B2O3·H2O was obtained. Thermodynamic properties of this compound were also calculated by a group contribution method. 相似文献
17.
Ben Hui Wang Ji De Wang RuiQuan Liu Ya Hong Xie Zhi Jie Li 《Journal of Solid State Electrochemistry》2007,11(1):27-31
A new type of oxide–salt composite electrolyte, yttrium doped ceria YDC–Ca3(PO4)2–K3PO4, was developed and demonstrated for its promising use for ammonia synthesis. Using this composite electrolyte, ammonia was
synthesized from nitrogen and natural gas at atmospheric pressure in the solid-state proton conducting cell reactor, and the
optimal condition for ammonia production was determined . The evolved rate of ammonia is up to 6.95×10−9 mol s−1 cm−2. 相似文献
18.
Pinyang Fang Huiqing Fan Shaojun Qiu Liajun Liu Jin Chen 《Journal of Sol-Gel Science and Technology》2009,50(3):290-295
Lanthanum-modified bismuth titanate (Bi3.25La0.75Ti3O12, BLTO) powders were prepared by the complex polymerization method. The structure and morphology of BLTO powders were investigated
by X-ray diffraction and scanning electron microscopy. The complexation of citric acid with the metallic cations was detected
by Fourier transformed infrared (FT-IR). The thermal analyses of obtained gels were investigated by differential thermal gravimetric
(DTG). The pure and normally stoichiometric phase of BLTO powders could be obtained at relatively low temperature of 550–700 °C
even if the bismuth content is not excess in the starting precursors, while the secondary phase could be detected at lower
and higher calcination temperatures. The shape of the BLTO grains is similarly to platelet in Bi-layer structure and stoichiometry
BLTO was detected by the analysis of energy dispersive spectrometry. 相似文献
19.
Using Fe3O4 nano-particles as seeds, a new type of Fe3O4/Au composite particles with core/shell structure and diameter of about 170 nm was prepared by reduction of Au3+ with hydroxylamine in an aqueous solution. Particle size analyzer and transmission electron microscope were used to analyze
the size distribution and microstructure of the particles in different conditions. The result showed that the magnetically
responsive property and suspension stability of Fe3O4 seeds as well as reduction conditions of Au3+to Au0are the main factors which are crucial for obtaining a colloid of the Fe3O4/Au composite particles with uniform particle dispersion, excellent stability, homogeneity in particle sizes, and effective
response to an external magnet in aqueous suspension solutions. UV-Vis analysis revealed that there is a characteristic peak
of Fe3O4/Au fluid. For particles with d(0.5)=168 nm, the λmax is 625 nm. 相似文献
20.
Ca3Co4O9 powder was prepared by a polyacrylamide gel route in this paper. The effect of the processing on microstructure and thermoelectric
properties of Ca3Co4O9 ceramics via spark plasma sintering were investigated. Electrical measurement shows that the Seebeck coefficient and conductivity
are 170 μV/K and 128 S/cm, respectively, at 700 °C, yielding a power factor value of 3.70 × 10−4 W m−1 K−2 at 700 °C, which is larger than that of Ca3Co4O9 ceramics via solid-state reaction processing. The polyacrylamide gel processing is a fast, cheap, reproducible and easily
scaled up chemical route to improve the thermoelectric properties of Ca3Co4O9 ceramics by preparing the homogeneous and pure Ca3Co4O9 phase. 相似文献