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Hu X.,Xiamen University | Guo Y.,Xiamen University | Guo Y.,Xiamen Zijin Mining and Metallurgy Technology Co. | Wang L.,Xiamen University | And 3 more authors.
Journal of Supercritical Fluids

A supercritical fluid-based method is proposed to produce coenzyme Q 10 (CoQ10) nanoparticles. First, CoQ10/ polyethylene glycol 6000 composite particles are prepared by a modified PGSS (particles from gas-saturated solutions) process with controlling the flow rate of the gas-saturated solution. Then, CoQ10 nanoparticles are obtained by dissolving the composite particles into water. The effect of experimental variables of the modified PGSS process, including pressure, temperature, flow rate of the gas-saturated solution, and mass fraction of CoQ10, on the CoQ10 particle size and particle size distribution was investigated. Results show that CoQ10 slurry product with a median diameter of 190 nm and yield of 89.8% can be prepared at an optimum condition (operating pressure of 25 MPa, operating temperature of 80 °C, gas-saturated solution flow rate of 1.02 mL/min, CoQ10 mass fraction of 40% and nozzle diameter of 100 μm) via the supercritical fluid-based method. © 2011 Elsevier B.V. All rights reserved. Source

Zhang N.,Xiamen Zijin Mining and Metallurgy Technology Co.
Yejin Fenxi/Metallurgical Analysis

A determination method of silicon dioxide in copper concentrate and lead concentrate by inductively coupled plasma atomic emission spectrometry (ICP-AES) was developed. The sample was melted at high temperature in corundum crucible using sodium peroxide as flux. The fusion cake was leached with hot water and acidified with hydrochloric acid. After matrix dilution, the internal standard element Au was added. The effects of matrix and instrumental fluctuation could be effectively eliminated using internal standard calibration method. The detection limit of silicon dioxide in this method was 0.0063 μg/mL, and the determination range (mass fraction) was 0.02%-10%. The proposed method had been applied to the determination of certified reference materials of copper concentrate and lead concentrate. The determination results were in good agreement with the certified values, and the RSD(n=5) was less than 3%. Source

Huang Y.-X.,Xiamen University | Liu B.,Xiamen University | Wen L.,Xiamen University | Zhang X.,Xiamen University | And 6 more authors.
Inorganic Chemistry

Structural assembly from phosphate to germanophosphate by applying germanate as a binder has been achieved. Two isotypic porous compounds, K 3[MII 4(HPO4)2][Ge 2O(OH)(PO4)4]·xH2O (M II = Fe, Cd; x = 2 for Fe and 3 for Cd, denoted as KFeGePO-1 and KCdGePO-1, respectively), contain a known transition-metal phosphate (TMPO) layer, ∞2{[M2(HPO4)3] 2-}, which is built from chains of trans-edge-sharing MO6 octahedra bridged by MO5 trigonal bipyramids that were further linked and decorated by phosphate tetrahedra. The layers are bound by infinite chains of GeO5(OH) octahedra, resulting in a 3D open-framework structure with 1D 12-ring channels that are occupied by K+ ions and water molecules. The curvature of the TMPO layers and shape of the 12-ring windows can be tuned by the transition metals because of their Jahn-Teller effect. © 2013 American Chemical Society. Source

Huang H.,Xiamen Zijin Mining and Metallurgy Technology Co.
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica

Incorporating multi-functional nano-particles into natural fiber reinforced polymer composites can provide with the multi-functionality, making them possess sensor performance, which are capable of in-situ sensing the change of surrounding environment. However, it is realized by dispersing nano-particle into matrix, which normally leads to high viscosity of matrix, hindering its application and meanwhile high nano-particle loadings are needed to reach percolation threshold. Dip coating technology was used for the surface modification of sisal fibres (SF) with multi-walled carbon nanotubes (MWCNTs) dispersion as dye, the resulting MWCNTs modified sisal fibers (MWCNTs-SF) and their epoxy based composite (MWCNTs-SF/EP) sensors were prepared. A continuous and homogenous dispersed MWCNTs network coating forms on surface of MWCNTs-SF. The current versus voltage characteristic curve of MWCNTs-SF indicates the formation of ohmic contacts for MWCNTs-MWCNTs and MWCNTs-electrode. Both MWCNT-SF and MWCNTs-SF/EP are characterized by negative temperature coefficient thermistor. Under external strain-stress, the electrical resistance of MWCNTs-SF and MWCNTs-SF/EP exhibits nearly constant at very low strains, then increases linearly at intermediate strains, while an exponential correlation between electrical resistance and strain exists at higher strains. The different sensing characteristics for MWCNTs-SF and MWCNTs-SF/EP mostly relate to the MWCNTs network structure change during consolidation. The tensile strength of MWCNTs modified sisal fiber fabric reinforced epoxy based composite increases gradually from 37.6 MPa to 46.7 MPa with increasing surface modification time, elastic modulus also increases accordingly. ©, 2015, Beijing University of Aeronautics and Astronautics (BUAA). All right reserved. Source

Zhang N.,Xiamen Zijin Mining and Metallurgy Technology Co.
Yejin Fenxi/Metallurgical Analysis

The ore sample was treated by alkali fusion and acidification, and tungsten and molybdenum were then simultaneously determined by inductively coupled plasma atomic emission spectrometry(ICP-AES). The interference of matrix sodium introduced during sample fusion to testing elements was investigated. The results showed that the matrix effect was obvious, and it was aggravate with the increase of sodium concentration. The instrumental stability was then seriously reduced, influencing the accuracy of determination results. By selecting optimal excitation conditions and proper analytical lines, the interference of matrix elements(sodium, iron, calcium and aluminum) contained in sample or introduced in sample fusion process could be eliminated by dilution. The detection limits for tungsten and molybdenum were 0.010 μg/mL and 0.004 μg/mL, respectively. The limit of detection for tungsten and molybdenum were 0.03%-6% and 0.01%-6%, respectively. The proposed method was applied to the determination of ore standard sample, and the results were consistent with the certified values. The relative standard deviations(RSD) were 0.78%-2.7%. Source

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