Advanced Materials Research Vols. 391-392

Abstract: The Sm³⁺-doped Ca₁₀(PO₄)₆(OH)₂ nanowires are synthesized by hydrothermal method. X-ray diffraction confirmed that the nanowires are made of the hexagonal Ca₁₀(PO₄)₆(OH)₂. Scanning electron microscope and transmission electron microscope analysis show that the lengths of the nanowires are approximately 5μm, and their diameters are around 100 nm, and the aspect (length/diameter) ratio is about 50. The room temperature photoluminescence (PL) spectra of Sm³⁺-doped Ca₁₀(PO₄)₆(OH)₂ nanowires doped with different Sm³⁺ concentration under 405 nm excitation has been investigated. It is found that there are three main sharp emissions peaks at near 569, 604, and 649 nm. The three emissions are due to the f-f forbidden transitions of the 4f electrons of Sm³⁺, corresponding to ⁴G_5/2→⁶H_5/2 (569 nm), ⁶H_7/2(604 nm), and ⁶H_9/2(649 nm), respectively. In addition, concentration quenching is also observed. It is found that the Sm^{3+ 4}G_5/2→⁶H_7/2(604 nm) emission intensity of Sm³⁺-doped Ca₁₀(PO₄)₆(OH)₂ nanowires significantly increases with the increase of Sm³⁺ concentration, and shows a maximum when Sm³⁺ doping content is 0.5%. If Sm³⁺ concentration continues to increase, namely more than 0.5%, the Sm^{3+ 4}G_5/2→⁶H_7/2 emission intensity decreases.

Abstract: We perform first-principles calculation of the transport properties of alumium-phosphorus dopped Si atomic nanowire coupled to two Al(100) nanoscale electrodes using the non-equilibrium Green formalism combined with the density-functional theory. In particular, the alumium-phosphorus dopped silicon wire with seven atoms sandwiched between the Al(100) electrodes is considered. It is found that the transport properties are sensitive to the dopping position of the alumium and the phosphorus on the silicon wire. The equilibrium conductance of the pure silicon wire is rather big, close to 3 G0, Three eigenchannels which contribute to the equilibrium conductance are fully open. All cases of the alumium-phosphorus dopping reduce the conductivity of the pure silicon wire. In particular, the conductance of the wire decreases to 0.7 G0 when a phosphorus substitutes the third silicon atom and a alumium substitutes the sixed silicon atom. The current-voltage(I-V) curves of these cases vary dramatically. The current across the wire with a phosphorus substitutes the third silicon atom and a alumium substitutes the sixed silicon atom is rather smaller than the that across the pure silicon. A detailed analysis of the transmission coefficient of the eigenchannels, the projected density of states are made to reveal the mechanism of the differences.

Abstract: Luminescence behaviors and morphology of Eu³⁺ doped hydroxyapatite synthesized under different pH values were well investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Inductively Coupled Plasma (ICP) (ICP–PLASMA 1000), and photoluminescence (PL) spectroscopy. Results revealed that With pH values increased from 6.5 to 10.0, the morphology of nano-Eu:HA particles changes from rod particles to equiaxed particles. The actual doping concentration and aspect ratio of Eu³⁺-doped HA decreased with the increasing of pH value. At the same time, the fluorescence intensity also tends to weakly lower with the increasing of pH value, which indicated that the luminescence properties mainly depended on the actual Eu³⁺ doping concentration, the influences of morphology on the luminescence properties were slight.

Abstract: Mineralogical examinations of Asheler copper mine flotation tailings have been carried out. Results show that the major metal sulphide minerals are pyrite and the main gangue constituents are quartz, chlorite-serpentine and muscovite. The main valuable metals are Cu, Zn and Ag. Basic mineral compositions of copper and zinc have been identified through chemical phase analysis. On the basis of mineralogical examinations, leaching test has been carried out in about 240g/l NaCl solution. The optimum conditions for leaching are found as follows: temperature at 86°C, pulp concentration is 24.19%wt, [Cu²⁺] =19.22g/l, [HCl] _initial =0.17mol/L. Under these conditions, chloride leaching can extract 83.35%Cu, 92.10%Zn, and 85.26%Ag after 8 hours leaching.

Abstract: Three commercial extractants LIX984N, LIX606N and LIX973N were chosen for the research on Cu²⁺ extraction from the solutions bearing high concentration of sulfuric acid and iron. The ability of Cu²⁺ extraction and Cu/Fe separation performance were totally compared among the three extractants. The results show that LIX606N and LIX973N both possess more powerful ability in Cu²⁺ extraction as compared to LIX984N. But, LIX973N and LIX984N has better Cu/Fe separation performance than LIX606N. According to the performance of Cu²⁺ extraction and Cu/Fe separation, LIX973N is more suitable for extracting Cu²⁺ from the solution rich in sulfuric acid and Fe³⁺.Effects of sulfuric acid and Fe³⁺ concentration on Cu²⁺ extraction by 20%LIX973N-kerosene have been examined. When aqueous sulfuric acid concentration increases from 23.48g/L to 62.16g/L, Cu²⁺ extraction recovery drops from 60.42% to 25.21%; When aqueous Fe³⁺ concentration increases from 7.03g/L up to 42.94g/L, Fe³⁺ concentration in organic phase increases from 0.26g/L to 0.82g/L.

Abstract: The paper has studied the process of using H₂O₂ as oxidant and tungsten acid as catalyst, catalytic oxidation synthesis process of cyclopentene to glutaraldehyde and explored the main influence factors of the reaction, including the reaction time, reaction temperature, catalyst dosage and solvent. Furthermore, the quantitative analysis and qualitative analysis of the product was characterized by gas chromatography. The optimum synthetic condition was as follows: tertiary butanol as solvent, tungsten acid: boron anhydride(mass ratio)=1:1, 30%H₂O₂ as oxidant, the reaction temperature 35°C, the reaction time 4h, the yield of glutaraldehyde yield was 46%.

Abstract: The self-aggregation of polysaccharides (PS) in solution has led to high viscosity, unstable biological activity and poor resolution in instrumental characterization as well. In this work, ultrasound with low power level was applied to disrupt the PS aggregation of an exopolysaccharide(EPS) from Cordyceps sinensis mycelial culture. Ultrasonic irradiation with 20% amplitude (about 4 W) for 0.5 min decreased the specific viscosity of EPS by 59%. Dynamic light scattering(DLS) experiments on native EPS showed four distinct population with diameter range of 10~500 nm, 500~2500 nm, 3500~12300 nm and 22150~115400 nm respectively. The peaks at large size range in the intensity-weighted size distribution disappeared or shifted to small size range, indicating a gradual disassociation of EPS with the prolongation of ultrasonic duration. AFM observation proved the disassociation of EPS from a highly across-linked gel into single strand under ultrasonic treatment. According to DLS analysis, ultrasonic treated EPS did not show any sign of aggregation over 8 days in contrast to an immediate aggregation growth with native EPS. Ultrasonic irradiation control PS association by means of weakening the hydrogen bonds through the hydrodynamic shear forces arising from acoustic cavitation in the irradiated liquid, which has importance in the applications and structural characterization of PS.

Abstract: N,N-dimethyl-1-adamantane was synthesized from amantadine through Eschweiler-Clarke reaction, The optimal ratio of amantadine, formic acid and formaldehyde was 1:5:4, and the reaction time was 18 h at 98°C.The product yield was 93.4% on these conditions. N,N,N-trimethyl-1-adamantyl quaternary ammonium salt then was synthesized, the product yield was 90.5%, succeeding eco-friendly procedure technology was developed. N,N,N-trimethyl-1-adamantyl quaternary ammonium hydroxide was obtained finally, target product yield was 84.3%.The structure of compounds were characterized by ¹H NMR, ¹³C NMR, MS and GC-MS.

Abstract: The copolymerization of AM and AANa was initiated by plasma at ambient temperature and pressure by the dielectric barrier discharge technology in this work. The alternative copolymers are confirmed by FTIR. The effect of initiation time, polymerization temperature, monomer mass fraction, mole rate of AM to AANa and postpolymerization time on the conversion rate and molecular weight of the copolymers were studied. The molecular weight of the copolymers can be further increased by post-polymerization,and the plasma-initiated polymerization in this experiment was proven to follow the free radical polymerization mechanism.

Abstract: A study was made on plasma-initiated polymerization of polyacrylamide (PAM) with high superabsorbent property. The viscosity-averaged molecular weight Mη of this PAM was 6.2×106g/mol in the measurement of viscosity by using water as solvent. Its conversion and water absorption calculated are 70% and 300g/g respectively. The effects of plasma discharge time, polymerization temperature and duration on the conversion and the molecular weight of the products were also investigated. The results of this study suggested that the method of plasma initiated polymerization could greatly enhance the molecular weight and water absorption property of the polymer.