Key Engineering Materials Vol. 636

Abstract: In this present study, A comparative research on the mechanical properties of the dissimilar welded joints of 800H and Cr18Ni30Mo2Al3Nb was investigated. Butt joints were made using argon tungsten-arc welding (TIG). The TIG joint was made using well established welding parameters (i.e., current ampere of 110~120A, welding rate of 105~115mm/min, argon flow 8~10L/min and voltage of 12V). Mechanical behavior of joints was evaluated by room temperature and high temperature (650°C) tensile testing, and hardness testing, respectively. The microstructure of joint was characterized via optical microscopy, and the morphology of tensile fracture was observed by scaning electron microscopy. As can be seen from the experimental results, clearly shown that Cr18Ni30Mo2Al3Nb has better mechanical performance of welded joint than 800H.

Abstract: Tungsten-containing functional mesoporousW-SiO₂ have been successfully synthesized by an one-pot and facile room-temperature procedure. These materials presented a high dispersion of tungsten species and excellent catalytic activity on the removal of sulfur compounds without any organic solvents as extractants. The catalytic performance on sulfur compounds was investigated in detail. After recycling for 8 times, the removal of the oxidation desulfurization system could still reach 92.0%.

Abstract: In the present work, rapidly solidified Al-21Si-0.8Mg-1.5Cu-0.5Mn alloys strips was prepared by melt-spinning technique. The microstructure morphology and phase structures of experimental alloy were characterized by means of scanning electron microscopy (SEM), transmission electric microscopy (TEM) and XRD technique. The results show that the grains were refined and the micro-nanocomposite structural were formed under rapid solidification. The nucleation and growth of primary silicon were suppressed and primary silicon could not deposited, meanwhile, α-Al phase was nucleated which prior to eutectic. The microstructure of the Al-21Si alloy was composed of micro-nanostructured α-Al phase and feather-needles-like eutectic α-Al+β-Si phase. The hypereutectic Al-21Si alloy showed the hypoeutectic microstructure. The rapidly solidified Al-21Si alloy microstructure formation mechanism has also been discussed.

Abstract: Systematic research on Monomolecular Layer of Copper (II) Phthalocyanine (CuPc) and porphyrin (Por) derivatives bas been done. In this paper an attention is focused upon the molecular orientation in monomolecular layer of some symmetrically and asymmetrically substituted CuPc and Por by means of the surface pressure-area (π-A) isotherm method, the transmission electron micrographs (TEM) , polarized UV-visible spectra.

Abstract: The 5% Fe-doped ZnO nanorods (Zn_0.95Fe_0.05O) were prepared successfully by the wet-chemical synthesis method. Structure and morphology characterization were demonstrated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Laser power dependent photoluminescence (PL) spectra were measured to study the electronic structures of the Fe-doped ZnO-based diluted magnetic semiconductors. The contraction of lattice constant and structured green-yellow-red emissions were analyzed. Such investigations confirmed that the induced defects or impurities originating from Fe ions.

Abstract: We present a new Al-Cu-Mn system to fabricate nanoporous copper ribbons by dealloying. The microstructures of the nanoporous copper ribbons are characterized using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The results show that the compositions of the melt-spun Al-Cu-Mn alloys have an important effect on the dealloying process and microstructures of the nanoporous copper ribbons. The melt-spun Cu₃₀Al₄₀Mn₃₀, Cu₃₀Al₃₅Mn₃₅, Cu₃₀Al₃₀Mn₄₀ and Cu₃₀Al₂₅Mn₄₅ (at.%) alloys can completely form a bicontinuous interpenetrating ligament-channel structure. Compared with other alloys, the dealloying of Cu₃₀Al₄₀Mn₃₀ alloys is more difficult. In addition, for Cu₃₀Al₃₅Mn₃₅ and Cu₃₀Al₃₀Mn₄₀ alloys, porous structures are relatively uniform. But for the Cu₃₀Al₂₅Mn₄₅ alloys, porous structure is not uniform, occurring aggregation phenomenon.

Abstract: Series of silicon-substituted hydroxyapatite were prepared and characterized, and their ability to degrade methyl orange and Congo red in aqueous solutions were studied. The effect of substituted silicon amount on the photocatalytic degradation efficiency of the dyes was investigated. The substitution of SiO₄⁴⁻ groups for PO₄³⁻ groups caused OH⁻ loss and difference in the microstructure of hydroxyapatite, and the elimination rates of silicon-substituted hydroxyapatite decreased with the increasing of substituted silicon amount compared to that of pure hydroxyapatite.

Abstract: Glycerol can be biologically converted to 1,3-propanediol (1,3-PD), a key raw material required for the synthesis of polytrimethylene terephthalate and other polyester fibers. 1,3-propanediol oxidoreductase (PDOR) is the rate-limiting enzyme in 1,3-PD synthesis biologically pathway. In present study, the dhaT gene encoding PDOR was cloned from Citrobacter freundii and overexpressed in E. coli BL21. The recombinant enzyme was purified by nickel-chelate chromatography combined with gel filtration to study the enzymatic characterization. Specific activity of recombinant PDOR was 55.2 U/mg. K_m and V_max values were 8.9 mM, 40.2 U/mg respectively. Holoenzyme of PDOR maybe a decamer of which a monomer has a molecular mass of 43 kDa. This research may form a basis for the future work on biological synthesis of 1, 3-PD.

Abstract: Novel multifunctional core shell structure CdTe-Fe₃O₄@CS drug nanocarriers were developed. The water soluble Fe₃O₄ nanoparticle was prepared by chemical coprecipitation method. The highly fluorescent CdTe QDs were prepared by refluxing method. The prepared Fe₃O₄ and CdTe QDs nanoparticles were capped with chitosan by ionic gel method to form multifunctional nanomaterials. After processing parameters affecting the end product properties were systematically optimized, folic acid, a model drug, was successfully incorporated into the polymeric complex.

Abstract: Uniform Fe₃O₄@TiO₂ nanocomposites were successfully synthesized via a sol-gel method and then characterized by transmission electron microscope (TEM) and X-ray diffraction (XRD). The obtained composites were monodispersed spherical nanoparticles with average diameter of ~ 230 nm. In vitro cytotoxicity experiment, Fe₃O₄@TiO₂ nanocomposites exhibited good biocompatibility and obvious sonodynamic therapy (SDT) effect. Over 50% cells were killed when the cells were treated with Fe₃O₄@TiO₂ and ultrasound for 1 min. The results indicated the potential of Fe₃O₄@TiO₂ for targeted sonodynamic therapy of tumor.