共查询到20条相似文献,搜索用时 875 毫秒
1.
TiO2 films were prepared by sol-gel method. In order to improve the utilization of light, the technologies of implantation of
transition metal ions (V+ and Cr+) and electron beam irradiation to deposit noble metal particles (Ag and Pt) were used. A red shift was found in the spectrum
of modified TiO2 films. The photocatalytic experiments showed that the photocatalytic ability under visible light irradiation could be improved
dramatically by both the implantation of transition metal and the electron beam irradiation.
__________
Translated from Chinese Journal of Catalysis, 2007, 28(1): 39–44 [译自: 催化学报] 相似文献
2.
Xiaolei Zhang Mingwang Pan Shengnan Xing Jingsheng Li 《Frontiers of Chemistry in China》2008,3(1):27-32
An ionomer-type of polyurethane (PU) emulsion was prepared from toluene diisocyanate (TDI), polypropylene glycol (PPG) and
dimethylol propionic acid (DMPA) following a self-emulsification process. The modified poly(vinyl chloride) (PVC) emulsion
resin was obtained by in situ emulsion copolymerization using the PU as seeds in an autoclave. The effects of PU molecular
weight on the mechanical properties and thermal stability of the PU/PVC materials were investigated. The composite latex particles
and composite materials were determined and characterized using a laser particle size analyzer, transmission electron microscopy
or scanning electron microscopy. The study results showed that the PU/PVC hybrid emulsion particles possess a core/shell structure.
When the general mechanical properties of the composite materials increase, the thermal stabilities decrease a little. The
tough fractures on the surface of the PU/PVC composite sample following impact are quite obvious.
__________
Translated from Journal of Hebei Normal University (Natural Science Edition), 2007, 31(2): 228–232 [译自: 河北师范大学学报(自然科学版)] 相似文献
3.
A nano-alumina with high specific area was prepared using a homogeneous precipitation method with titanium dioxide and barium
oxide as modifying additives. Results showed that 5 wt% TiO2 or BaO added in the alumina gels can decrease the particle size and increase the specific area, but excessive TiO2 or BaO could deteriorate the properties of α-Al2O3.
__________
Translated from Journal of Shandong University of Technology (Natural Science Edition), 2007, 27(3): 23–26 [译自: 山东理工大学学报(自然科学版)] 相似文献
4.
Jie Gong Yang Liu Lili Wang Jinghai Yang Zhanguo Zong 《Frontiers of Chemistry in China》2008,3(2):157-160
Hexagonal close-packed Ni nanoparticles were synthesized using a heat-treating technique with the precursors prepared by the
sol-gel method. The synthesis condition, structure, and morphology of the samples were characterized and analysed by thermogravimetric
analysis (TG), differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results
indicate that the hexagonal close packed Ni nanoparticles were synthesized at a heat-treating temperature of 300°C. The cell
constants are calculated at a = 0.2652 nm and c = 0.4334 nm. The average grain size of the hexagonal close-packed Ni particles evaluated by Scherrer equation is about 12
nm. The phase transformation from a hexagonal close-packed Ni to a face-centered cubic Ni structure occurred when the heat-treating
temperature was increased.
__________
Translated from Chemical Journal of Chinese Universities, 2007, 28(7): 1232–1234 [译自: 高等学校化学学报] 相似文献
5.
Nanocrystalline niobium doped lead zirconate titanate powders (PZTN) were prepared by a citrate-nitrate sol-gel combustion
technique. The technique involves three steps: preparation of stable and homogeneous sol, formation of gel, combustion of
gel. The sol was prepared by mixing stable solutions of Zr-oxynitrate, Pb-citrate, Nb- and Ti-peroxo-citrate precursors. The
heat induced auto ignition leads to the decomposition of precursors and formation of pure perovskite phase after soaking at
400∘C for 4 h. The particles were found to be irregular aggregates of nanosized primary particles (crystallite size about 30 nm).
Different milling treatments were performed in order to improve the sinterability. Ball milled (100 h with PEG) powders were
sintered at 1100∘C for 2 h in air showing 97% relative density at a densification T 100∘C lower than following the conventional mixed oxide route. The stoichiometry of the system was determined at each stage of
the process and no fluctuation was detected. 相似文献
6.
Bitao Su Ke Wang Jie Bai Hongmei Mu Yongchun Tong Shixiong Min Shixiong She Ziqiang Lei 《Frontiers of Chemistry in China》2007,2(4):364-368
Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized
by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultravioletvisible spectroscopy (UV-Vis) diffuse reflectance
spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic
activity of Fe3+/TiO2 nanoparticles under visible light irradiation. The influence of doping amount of Fe3+ (ω: 0.00%–3.00%) on photocatalytic activities of TiO2 was investigated. Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorption spectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The
appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.
__________
Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(6): 55–56 [译自: 西北师范大学学报(自然科学版)] 相似文献
7.
Using an emulsification-gelation method, chitosan-sodium alginate-porcine hemoglobin microcapsules were prepared. Results
show that these microcapsules have better forms and small granules with 1 μm size of the mean particle size. They possess
a relatively narrow and normal Gaussian distribution. The loading efficiency of porcine hemoglobin (pHb) in microcapsules
is more than 90%. The pHb released from microcapsules is extended for more than one month. Chitosan-sodium alginate-hemoglobin
microcapsules are expected to become an artificial oxygen-carrying therapeutic agent with sustained release for intravenous
injection.
Translated from Journal of Hainan University (Natural Science) 2006, 24(3): 239–242 [译自 海南大学学报 (自然科学版)] 相似文献
8.
A novel compound of butyl crystal violet lactone (BCVL) has been prepared by oxidizing leuco butyl crystal violet lactone
(LBCVL), which was obtained by the mixture of N,N-dibutylaniline, p-(dibutylamino) benzaldehyde and methyl-m-(dibutylamino) benzoate. The structure of BCVL was characterized by 1H-nuclear magnetic resonance (NMR), infrared (IR), and mass spectrometry (MS). The color of BCVL can change reversibly in
some acid or alkali solvents. The result of the dissolution experiment showed that solubility of BCVL in organic solvent was
improved compared with crystal violet lactone (CVL).
Translated from Journal of Fudan University (Natural Science), 2006, 45(3): 375–379 [译自: 复旦学报(自然科学版)] 相似文献
9.
Lingang Li Yu Tang Yuanming Zhang Jun Yang Biying Du 《Frontiers of Chemistry in China》2008,3(1):76-80
ZnS hollow nanospheres with holes were prepared by reacting ZnSO4 with H2S, the sulfide source formed in the reaction of CS2 with ethylenediamine, 1,3-propylenediamine, butylamine or 2-(2-aminoethylamino) ethanol, which also acted as a template agent,
at 50°C under agitation. The shape, particle size of about 100–850 nm and hole size of about 150–600 nm of ZnS hollow nanospheres
with holes were shown by SEM and TEM images. These ZnS nanospheres with β cubic ZnS phase and composed of 2–5 nm nanocrystals
were characterized by XRD and HRTEM. The blue shift of maximum absorption in UV-vis displayed the effect of quantum size.
The two amino groups of amine templates reacted favorably with Zn2+ to form uniform and relatively smooth ZnS nanospheres with holes, while hydroxyethyl played a disadvantageous role. A reasonable
mechanism of hole formation by H2S rushing out is suggested.
__________
Translated from Journal of Jinan University (Natural Science), 2007, 28(1): 92–95 [译自: 暨南大学学报(自然科学版)] 相似文献
10.
Kinetics of thermal decomposition of CeO2 nanocrystalline precursor prepared by precipitation method
Xiaolan Song Xi He Haiping Yang Dayu Xu Nan Jiang Guanzhou Qiu 《Frontiers of Chemistry in China》2008,3(2):182-185
The thermal decomposition of CeO2 nanocrystalline precursor prepared by chemical precipitation method was investigated using thermo-gravimetric/differential
scanning calorimetry (TG/DSC) and X-ray powder diffraction (XRD). In particular, the differential thermal analysis curves
for the decomposition of CeO2 nanocrystalline precursor were measured at different heating rates in air by a thermal analyzer (NETZSCH STA 449C, Germany).
The kinetic parameters of the thermal decomposition of CeO2 nanocrystalline precursor were calculated using the Kissinger method and the Coats-Redfern method. Results show that the
apparent active energy E of the reaction is 105.51 kJ/mol, the frequency factor lnA is 3.602 and the reaction order n is 2. This thermal decomposition process can be described by the anti-Jander equation and a three-dimensional diffusion mechanism.
Tanslated from Journal of Central South University (Science and Technology), 2007, 38(3): 428–432 [译自: 中南大学学报(自然科学版] 相似文献
11.
M. R. Barati 《Journal of Sol-Gel Science and Technology》2009,52(2):171-178
Nanocrystalline Mg–Cu–Zn ferrite powders were successfully synthesized through nitrate–citrate gel auto-combustion method.
Characterization of the nitrate–citrate gel, as-burnt powder and calcined powders at different calcination conditions were
investigated by using XRD, DTA/TG, IR spectra, EDX, VSM, SEM and TEM techniques. IR spectra and DTA/TGA studies revealed that
the combustion process is an oxidation–reduction reaction in which the NO3
− ion is oxidant and the carboxyl group is reductant. The results of XRD show that the decomposition of the gel indicated a
gradual transition from an amorphous material to a crystalline phase. In addition, increasing the calcination temperature
resulted in increasing the crystallite size of Mg–Cu–Zn ferrite powders. VSM measurement also indicated that the maximum saturation
magnetization (64.1 emu/g) appears for sample calcined at 800 °C while there is not much further increase in M
s at higher calcination temperature. The value of coercivity field (H
c) presents a maximum value of 182.7 Oe at calcination temperature 700 °C. TEM micrograph of the sample calcined at 800 °C
showed spherical nanocrystalline ferrite powders with mean size of 36 nm. The toroidal sample sintered at 900 °C for 4 h presents
the initial permeability (μ
i) of 405 at 1 MHz and electrical resistivity (ρ) of 1.02 × 108 Ω cm. 相似文献
12.
Xiaofeng Zhang Shen Lin Xinqing Chen Jiebo Chen Liuyi Yang Minghong Luo 《Frontiers of Chemistry in China》2007,2(4):419-421
Mesoporous aluminophosphate was prepared by using G4.0 poly(amido amine)dendrimer as a template and characterized by Fourier
transform infrared spectrometer (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption/desorption methods. Results show that the title compound exhibits a typical mesoporous structure with the average
pore size from 5 to 8 nm. The formation mechanism of the nanoporous structure using dendrimer as a template was also discussed.
__________
Translated from Journal of Fujian Normal University (Natural Science Edition), 2007, 23(2): 67–70 [译自: 福建师范大学学报 (自然科学版)] 相似文献
13.
The electrochemical behavior of ciprofloxacin (CFX) and its interaction with the natural calf thymus DNA (ctDNA) is studied
by using pulse difference voltammetry on a carbon electrode. CFX shows a well-defined oxidative peak at + 0.88 V. As a result
of reaction with ctDNA,the oxidative peak of CFX decreased markedly. According to the electrochemical equation deduced in
this paper, the binding constant of 1.36 × 105 (mol/L)−1 and the binding size of 1.94 (base pairs) of CFX with ctDNA were obtained by nonlinear fit analysis of the electrochemical
data. The mechanism of the interaction was explored.
__________
Translated from Journal of Zhejiang University (Science Edition), 2007, 34(3): 330–334 [译自: 浙江大学学报(自然科学版)] 相似文献
14.
Guosheng Liu Zhilin Ran Hailei Wang Yi Liu Ping Shen Yan Lu 《Frontiers of Chemistry in China》2008,3(1):70-75
Biological effect of rare-earth lanthanum nitrate on the growth of Escherichia coli B was studied using the calorimetric method. There were exceptional changes on the growth thermogenic curves for high concentrations
of lanthanum nitrate. For example, the peak high, the total quantity of heat (Q) of cultures and the growth rate constants (k) are evidently increased when compared with normal E. coli B cultures. When the concentration of lanthanum nitrate was at 300 mg/L and 500 mg/L, and Q of the cultures reached 3.89 and 2.54 times of normal cultures, respectively. The survivability of cells and the biomass
of the cultures were measured using biological methods and the results show that the growth and multiplication of cells were
inhibited and that the biomass decreased at high concentration of lanthanum nitrate. These revealed that the inhibiting cells
discharged more quantity of heat than the normal growing cells. We named this phenomenon as “eruption of heat”. It was suggested
that the mechanism for the eruption of heat was that La3+ ion damages the outer cell membrane and increases its permeability and the proton-electron potential energy across the cell
membrane was reduced or couldn’t even be initiated. Energy could not be translated into ATP effectively in the course of oxidative
phosphorylation resulting in heat release. So, the growth of the cells was inhibited due to scarceness of energy ATP.
__________
Translated from Acta Chimica Sinica, 2007, 65(10): 917–922 [译自: 化学学报] 相似文献
15.
ZrWMoO8 powders with different morphologies were obtained using ammonium tungstate, molybdate tungstate and zirconium tungstate as
the starting materials by dehydrating the precursor ZrWMoO7(OH)2(H2O)2. The precursor was studied by thermo-gravimetric and differential scanning calorimetry (TG-DSC). The influence of the gelling
agents (HCl, HClO4, HNO3, H2SO4 and H3PO4) on the crystallization process and crystal morphology of the products prepared was investigated by X-ray powder diffraction
(XRD), scanning electron micrograph (SEM) and X-ray fluorescence spectrometer (XRF). Results showed that the morphology of
the ZrWMoO8 particles can be simply adjusted by changing the gelling agents, and the thermal expansion coefficients of cubic ZrWMoO8 prepared in HCl solution are −3.84 × 10−6 K−1 from 100°C to 700°C.
__________
Translated from Chemical Journal of Chinese University, 2007, 28(3): 397–401 [译自: 高等学校化学学报] 相似文献
16.
A nitrate-citrate-silica gel was prepared from metallic nitrates, citric acid, and silica powder by sol-gel process, and it was further used to synthesize Ni0.5Zn0.5Fe2O4/5wt% SiO2 nanocomposites by auto-combustion. The effect of pH on the formation of NiZn ferrite/SiO2 and thermal properties of gel precursors was studied by XRD, IR, EPR, TGA and DTA techniques. The results revealed that the ratio of the citrate ion to the nitrate ion is directly related to the pH of the solution. The pH in the starting solution affects the combustion process, and then determines the particle size of the as-synthesized powder. The EPR parameters (peak-to-peak linewidth, g factor, and spin number) increased with increasing pH, whereas the spin-spin relaxation time (T2) decreased. The thermal stability and enthalpy of the decomposition process in air decreased with increasing pH, whereas the enthalpy in nitrogen increased. Moreover, the activation energy (Ea) of thermo-oxidative degradation of the gel precursor at pH 3 was much lower than the gel precursor at pH 5 and 7, and that increased with increasing pH. 相似文献
17.
Huixue Ren Yanzhao Yang Jimao Lin Yinshan Qi Yeqing Zhang 《Frontiers of Chemistry in China》2008,3(2):152-156
A new synthetic method for 5-bromo-3-sec-butyl-6-methyluracil (Bromacil) using 2-bromobutane and urea as starting materials is described. The synthesis involved condensation,
cyclization and bromination with a total yield of 60%. The structure of Bromacil was determined by 1H NMR, 13C NMR and IR spectroscopy.
__________
Translated from Journal of Shandong University (Natural Science Edition), 2007, 42(7): 9–12 [译自: 山东大学学报(自然科学版)] 相似文献
18.
One kind of built-in silica adsorbent, which has high adsorption selectivity to rutin, was synthesized using molecular imprinting
technology by the following steps: synthesis of precursor from the reaction between water soluble rutin (as template molecule)
and the functional monomer chloropropyltriethoxysilane, co-hydrolysis of the precursor and tetraethoxysilane (TEOS), sol-gel
aging process, and removal of template molecules. The results of adsorption experiment show that this adsorbent has a high
adsorption capacity for rutin, and good adsorption selectivity towards rutin even under the interference of a flavone with
a similar structure. TEM photos suggest that nanocaves corresponding to rutin were formed inside the adsorbent while FTIR
spectra indicate that new bond was generated during the recognition process.
__________
Translated from Journal of Tianjin University, 2007, 40(4): 411–415 [译自: 天津大学学报] 相似文献
19.
Yingpin Li Xiaoquan Zhou Huijing Zhou Zhurui Shen Tiehong Chen 《Frontiers of Chemistry in China》2008,3(2):128-132
Manganese dioxides with various morphologies were prepared using a common hydrothermalmethod without any templates or additives.
The evolution of the morphology was accompanied by the gradual conversion of the polymorphic forms from γ-type to β-type. Meanwhile, MnO2 microspheres, urchin-like nanostructures and nanowires were successfully synthesized. The products were characterized by
X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The
evolution process can be explained by the Ostwald Ripening mechanism.
__________
Translated from Chinese Journal of Chinese Universities 28(7): 1223–1226 [译自: 高等学校化学学报] 相似文献
20.
Sr2CeO4/Ln3+ (Ln = Er, Ho, Tm) phosphors were synthesized with the microwave radiation method for the first time. The luminescent properties
of the samples were investigated and the up-conversion luminescence of Er3+, Ho3+ and Tm3+ doped Sr2CeO4 phosphors was observed. The spectra indicate that the energy transfer takes place from the triplet excited state of MLCT
(metal-to-ligand charge transfer) state for Sr2CeO4 (sensitizer) to the rare earth ions (activator).
__________
Translated from Journal of Hebei Normal University (Natural Science Edition), 2007, 31(2): 212–216 [译自: 河北师范大学学报 (自然科学版)] 相似文献