High-strength fracturing proppant was prepared from bauxite (67wt% Al2O3) and dolomite. The micro-mechanism related with the strength improvement was addressed with systematic sintering experiments as well as phase co...
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High-strength fracturing proppant was prepared from bauxite (67wt% Al2O3) and dolomite. The micro-mechanism related with the strength improvement was addressed with systematic sintering experiments as well as phase composition/microstructure characterization. The results indicate that the addition of dolomite promotes the formation of liquid phase during sintering process. Liquid phase of samples plays three rules during sintering process: (1) depressing the sintering temperature;(2) facilitating the growth of rod-like mullite;(3) filling pores/bonding particles. Analyses suggest that the mechanical strength enhancement was introduced by the appearance of the interlocked rod-like mullite and the cross-linkage of particles by the liquid phase. The best performance of our proppant was achieved by 3wt% dolomite addition;the proppant exhibits a breakage ratio of less than 6% (69 MPa) with a 1290-1400°C sintering process, and this breakage ratio was depressed down to 2.9% with a sintering temperature of 1350°C. The bulk density and apparent density of the 1350°C sintered proppant are 1.75 and 3.12 g/cm3, respectively.
Firstly, the polystyrene (PS) microspheres with silver shell were synthesized by chemical reduction method. Subsequently, PS/Ag core-shell opals template was prepared using vertical deposition method, then TiO2 infilt...
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Firstly, the polystyrene (PS) microspheres with silver shell were synthesized by chemical reduction method. Subsequently, PS/Ag core-shell opals template was prepared using vertical deposition method, then TiO2 infiltrated into opal template by sol-gel method. Finally the samples were calcinated to remove PS microspheres, leaving TiO2/Ag inverse opal. The samples were characterized and investigated by SEM, TEM and XRD. The results showed that the surface of PS microspheres was coated by nano-silver;the unit cell parameters of the obtained TiO2/Ag core-shell inverse opals after calcination at 480°C for 12h can be controlled by adjusting the shell thickness of silver. In other words, PS/Ag microspheres with different shell thickness of silver, three-dimensional opals and inverse opals structure with different unit cell parameters can be obtained only by tuning AgNO3/PS mass ratio.
A green synthetic route is reported for quickly synthesis of highly luminescent CdTe-Mn/ZnS quantum dots (QDs) in aqueous solution. Glutathione (GSH) was used as capping reagent and thioacetamide (TAA) as sulfur sourc...
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Rod-like β-Ga2O3:Dy3+ blue/yellow phosphors doped with different concentration of Dy3+ were synthesized by the rapid microwave hydrothermal and calcination method. Although the crystallization of β-Ga2O3:Dy3+ sample...
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Rod-like β-Ga2O3:Dy3+ blue/yellow phosphors doped with different concentration of Dy3+ were synthesized by the rapid microwave hydrothermal and calcination method. Although the crystallization of β-Ga2O3:Dy3+ samples decreased as the Dy3+ concentration increasing, the samples' morphology maintained and were not influenced by the Dy3+ concentration under XRD and SEM characterizations. Photoluminescence measurement results showed that the emission peaks of β-Ga2O3:Dy3+ phosphors located at 492 nm (blue) and 580 nm (yellow), the intensity of blue/yellow emission varied with Dy3+ concentrations and showed a maximum when the concentration of Dy3+ at 3mol%, the corresponding blue/yellow ratio was 59.29%/40.71%. In addition, the probable mechanisms of GaOOH growth and Dy3+ doping into GaOOH:Dy3+ and β-Ga2O3:Dy3+ were analyzed briefly.
GaOOH precursors with different morphologies and sizes were synthesized by hydrothermal method. The products were characterized by XRD, SEM and the probable growth mechanism of GaOOH was analyzed. The pH values played...
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GaOOH precursors with different morphologies and sizes were synthesized by hydrothermal method. The products were characterized by XRD, SEM and the probable growth mechanism of GaOOH was analyzed. The pH values played a dominated role in adjusting GaOOH morphologies and had an effect on their crystallizations. The GaOOH precursors were calcined in air and transformed into α-Ga2O3 and β-Ga2O3 under 600°C and 900°C, respectively. The samples after calcinations showed coincident morphology hereditability. Photoluminescence measurements(λex=250 nm) were conducted for the GaOOH and Ga2O3 samples and the emission peaks located at 415 nm and 465 nm when pH=5, however, at 370 nm and 465 nm for pH=3 and 8.
Radiofrequency low temperature plasma was used to mutate the strain B8 which can adsorb nickel ions, and the adsorptive ability of the mutant was tested. The experiments show that the optimum mutagenic conditions of B...
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Radiofrequency low temperature plasma was used to mutate the strain B8 which can adsorb nickel ions, and the adsorptive ability of the mutant was tested. The experiments show that the optimum mutagenic conditions of B8 by plasma are as follows: the mutation time of 3 min, the mutation power of 50~65 W, the carrier gas of N2 and the carrier gas pressure of 20 Pa. The mutant Ni12 with high adsorptive ability was screened from the mutant strains of B8 mutated under above conditions, and the nickel ion adsorption capacity of the mutant Ni12 reaches 136.7 mg · g-1 (dry bacteria), which is 11.7% higher than that of raw strain B8. The genetic stability of mutant Ni12 can maintain in 5 generations. The mechanism study shows that the extra cellular polymer is an important factor affecting the adsorption of nickel ions. After the formation of mutant Ni12 biofilm on the porous ceramics, from solution with nickel ion concentration of 50 mg · L-1, the nickel ion adsorption ratio of Ni12 reaches 86%. The result of 16S rDNA sequence analysis indicates that the mutant Ni12 is Pseudomonas cedrina. The advantage of mutagenesis of raw strain B8 by radiofrequency low temperature plasma is its high efficiency, and the inheritance of mutant strain Ni12 is stable. Therefore, it has promising prospect of using it to treat the wastewater containing nickel ions.
Nanogold particles in different sizes, from 5 to 60 nm, were utilized to modify the surface of the quartz crystal microbalance (QCM). It was found that the gold-particle size of the modified QCM affects both the amoun...
Nanogold particles in different sizes, from 5 to 60 nm, were utilized to modify the surface of the quartz crystal microbalance (QCM). It was found that the gold-particle size of the modified QCM affects both the amount of the immobilization of the probe on the surface of QCM and the hybridization rate of the target DNA. 20 nm was determined to be the optimal size for the surface modification and it can maximally increase the sensitivity of the DNA detection.
Using the chemical bath deposition for aqueous solution containing zinc acetate and ammonium hydroxide, the phase composition and morphology of samples, soluble Zn ion concentration in the mother liquid at different a...
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Using the chemical bath deposition for aqueous solution containing zinc acetate and ammonium hydroxide, the phase composition and morphology of samples, soluble Zn ion concentration in the mother liquid at different aging time were studied. The results indicated that octahedrally microcrystals of the stable intermediate Ε-Zn(OH)2 were produced at early stages under these conditions. Transformation from Ε-Zn(OH)2 to ZnO was observed to occur at various aging time. Transformation from Ε-Zn(OH)2 to ZnO followed two mechanisms: dissolution-reprecipitation and solid-solid phase transformation mechanism.
ZnO nanorod arrays were firstly grown on FTO conducting glass via a simple chemical bath deposition method, then ZnO nanorod arrays/nanoparticles aggregate composite films were obtained by sequential growth of ZnO nan...
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ZnO nanorod arrays were firstly grown on FTO conducting glass via a simple chemical bath deposition method, then ZnO nanorod arrays/nanoparticles aggregate composite films were obtained by sequential growth of ZnO nanorod arrays. The dye-covered ZnO electrodes, Pt counter electrode and electrolyte solution were assembled into dye-sensitized solar cells (DSSCs). Due to their relatively high surface area, fast electron transport, and enhanced light-scattering capability, a short current density(Jsc) of 11.7 mA/cm2, an open-circuit voltage (Voc) of 0.661 V, a fill factor(FF) of 0.384, and overall solar-to-electric energy conversion efficiency of 3.17% were achieved for the ZnO nanorod arrays/nanoparticles aggregate composite films DSSCs under sunlight illumination with AM1.5 (100 mW/cm2), which were much higher than those obtained for the monodisperse aggregate DSSCs and ZnO nanorod array DSSCs.
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