Advanced Materials Research Vols. 798-799

Abstract: Industrial washing oil as solvent, super pure coal was extracted and prepared from raw coal using heat extraction technology. The structures of raw coal and super pure coal were characterized by thermogravimetry and Fu Liye infrared spectrum. The results showed that the heat extraction rate of super pure coal was decreased with the increasing of coalification degree. The ash of raw coal which were silicate and alumina can be concentrated by heat extraction technology into coal residue and the mixtures of various structure were mainly composed of aromatic hydrocarbons also can be extracted effectively.

Abstract: Nickel oxide/yttrium stabilized zirconia (NiO/8YSZ) anodes with different amounts of pore formers for anode used for solid oxide fuel cell have been prepared by aqueous tape casting technique. The zeta potential of NiO/8YSZ aqueous suspensions with and without dispersants was characterized. Moreover, the viscosity of NiO/8YSZ aqueous suspensions with different amount of dispersants and pore formers were studied by the concentric cylindrical rotational viscometer. The microstructures of the anode with different amounts of pore formers were also studied by SEM. The electrochemical performance of the single cell with different amounts of pore formers (modified by 0.8 wt% of polyvinyl pyrrolidone (PVP) over graphite) was evaluated between 700 and 800 °C with hydrogen as the fuel and air as the oxidant. It was observed that the maximum power density of the single cell with the optimum amount of graphite content (20wt%) measured was over 0.8 Wcm-2 at 800 °C and the area specific resistance value was as low as 0.79Ωcm2. The study allowed identifying optimum amount of graphite modified by PVP as the most promising pore formers for the production of supporting anodes prepared by aqueous tape casting for intermediate temperature solid oxide fuel cell application.

Abstract: Quantum mechanical calculations have been performed to study the stereoselectivities in the direct cross-aldol reactions of aldehydes catalyzed by simple chiral diamines. The detailed computational studies on the stereochemistry-controlling step of the subject reactions have been presented by DFT calculations at the B3LYP/6-31G* level. The poor agreement between the calculated and the observed diastereomeric ratio and enantiomeric excess values is obtained for all diamines catalysts. Further M06-2X calculations can provide a reasonable explanation for the observed syn-selectivities of the asymmetric cross-aldol reaction between propionaldehyde and 4-nitrobenzaldehyde.

Abstract: Stable TiO₂ colloids composing of narrow size distrubuted anatase TiO₂ nanocrystals were prepared using quaternary ammonium hydroxide, such as Me₄NOH, Et₄NOH and Bu₄NOH, as catalyst. TEM and UV-Vis spectra measurements showed that the TiO₂ colloids are quite stable in air or under ultrasound irradiation and the size of the TiO₂ particles of the colloids can be tuned by changing the molar ratio of Titanium isopropoxide and the organic additive. The additive can be removed when the dried gel were calcined at 450°C for two hours, resulting in pure TiO₂ nanocrystal in anatase phase.

Abstract: Er³⁺/Yb³⁺ co-doped transparent phosphate glass ceramics were fabricated and characterized optically. The formation of nanocrystals is confirmed by x-ray diffraction. Stark split near infrared emission peaks of Er³⁺ have been observed in the glass ceramics, and the effective bandwidth increases with increasing annealing temperature. Upconversion emissions of Er³⁺ in the glass ceramics under 975nm wavelength excitation, especially in the green wavelength region, are enhanced. The results can be attributed to the enhancement of ligand field due to incorporation of Er³⁺ ions into the crystal lattices.

Abstract: Metamaterial-composite structured materials have abnormal electromagnetic capabilities. Presently these electromagnetic capabilities can be realized by periodical resonant structure such as SRRs,SR, and fractal resonator. Based on the SRRs structure, double split rectangular resonators can be constructed by connecting two SRRs. This type of resonators exhibites negative permeability and is more compacted. The detailed design process and retrieved process of equivalent material parameters are presented and the effect of negative permeability can be analysied. Compared to SRRs, double split rectangular resonator is smaller in size for the same resonance frequency and more convenient for miniaturization applications .

Abstract: A molecular orbital is the wave function for the electron, and it extends over the entire molecule. When considering the possible reactions of a molecule, molecular orbitals are required to be known. This paper gives insight into the nature of molecular orbitals and nodal plane, also explain why certain atomic orbitals “missing” in molecular orbitals.

Abstract: Super plastic behavior of the commonly as-extruded Mg-3Zn-1Al (ZA31) magnesium alloy is investigated at temperatures ranging from 593 to 623K and strain rates ranging from 8×10^-5 to 10^-3s^-1. The results show that the alloy exhibits excellent super plasticity and the maximum elongation-to-failure reaches 220.4%. The alloy also shows a high strain rate sensitivity exponent of 0.38. Microstructure observations suggest that grain boundary sliding (GBS) with cavity coordination makes a substantial contribution to the super plastic deformation.

Abstract: Laccases belonging to multicopper oxidase family oxidize a broad range of reducing substrates, especially industrial effluents-derived polyphenols, which causing major effect on human health as well as environment. In order to investigate the molecular mechanism of interaction between laccase and its substrate, it is a good idea to analyze three-dimensional structure of laccase. Based on crystal structure of Escherichia coli laccase CueO, the three-dimensional structure of Aeromonas hydrophila Laccase (Ah-lac) was constructed by homology modeling and further evaluated using PROSA energy and ERRAT. The substrate binding site in Ah-lac was predicted and the binding mode of 2,5-Xylidine as a putative ligand to Ah-lac was presented using molecular docking. The residues of Met378 and His382 in the binding pocket are responsible for the interactions with 2,5-Xylidine via two hydrogen bonds. The two residues could be important for substrate recognition.

Abstract: This is a review on the kinetic theory of granular media. In this paper, we discuss the main model for the granular media from the mathematic point, and the main results on this subject.