Advanced Materials Research Vols. 233-235

Abstract: Using Zn powder as the raw material, Tetrapod-like ZnO nanoneedles with controllable morphology and size were successfully prepared by chemical vapor deposition. A screen printed normal-gated triode with Tetrapod-like ZnO nanoneedles field emitters is demonstrated. Field emission measurements show that the Tetrapod-like ZnO nanoneedles FED triode devices posses a good field emission property. The turn-on voltage is 270V. An anode current of 2.75 mA and a gate current of 0.43 mA are extracted at a gate voltage of 600 V with a brightness of 2300 cd/m².

Abstract: Dispersion polymerization of acrylamide (AM) has been carried out in ethanol/water (90 v% ethanol) media with Polyvinylpyrrolidone(PVP) as a stabilizer, several surfactants as co- stabilizers, Sodium hydrogen sulfite (NaHSO₃) and ammonium persulfate ((NH₄)₂S₂O₈) as a redox initiator(I). The influences of initiators, monomer (AM), stabilizer and co-stabilizer concentration, the ratio and types of nonionic and anionic surfactants, pH on reaction stability and coalescence stability have been investigated. The results showed that as the initiator concentration increased, reaction stability declined, but the coalescence stability of emulsion increased. As the monomer mass percent lower than 20%, mass percent of PVP stabilizer between 6.15% and 8.12%, the high reaction stability reached. The surfactant composite consisted of nonionic and anionic surfactants had a better ability to stabilize the emulsion than any surfactant used alone. When m (OP-10): m (SDS) was 2:3, the mass percent of the emulsion is more than 3%, and the best reaction stability and coalescence stability were obtained. The suitable pH was 6.5.

Abstract: The reaction between SiC and AlF₃ has been investigated in CO atmosphere at high temperature. Experimental results are shown that the reaction intensity between SiC and AlF₃ is accelerated with the rise of temperature. At the temperature of 950 (aluminum electrolytic operation temperature is 935±15), the reaction intensity of SiC and AlF₃ is not high and the major reaction products are SiF₄ gas and Al₄C₃; Al₄C₃ occur severe hydration at room temperature which leads to the pulverization of specimens. The unexpected cells stop should try to be avoided or reduced during the usage of Si₃N₄-bonded SiC sidewall brick in aluminum electrolysis cells because of Al₄C₃ existents possibly.

Abstract: A three-dimensional, two-phase, multiple-component, unsteady model for the anode side of passive direct methanol fuel cells is presented in this work. The model is formed by a drift-flux model and can capture in-plane distributions of species along different directions in the cell. After grid independency test, this model is used to investigate numerically transport behaviors in the anode of liquid feed direct methanol fuel cells. The results illustrate the feasibility of the passively delivering methanol to the electrochemical reaction site, and characterize the relevant transport phenomena. Moreover, the evolution of species concentration, velocities along different directions in the cell and the mass transfer limitation were also presented. The three-dimensional model is valuable for understanding and predicting mass transfer in passive direct methanol fuel cells.

Abstract: The interaction between 4-aminobenzenesulfonic acid and bovine serum albumin (BSA) had been studied by fluorescence spectroscopy. The binding constant (K=2.51×10⁴) and binding points (n=0.998) of 4-aminobenzenesulfonic acid with BSA were determined at 298 K based on fluorescence quenching results. The thermodynamic parameters such as enthalpy change (ΔH), entropy change (ΔS) and Gibbs free-energy change (ΔG) for the reactions were also calculated according to the thermodynamic equations. The negative ΔH and ΔS values in case of 4-aminobenzenesulfonic acid-BSA complexes showed that van der Waals interactions and hydrogen bonds might play a major role in the binding of 4-aminobenzenesulfonic acid to BSA. The distance, r, between donor (BSA) and acceptor (4-aminobenzenesulfonic acid) was obtained according to the Förster’s theory of non-radiation energy transfer. The results of synchronous fluorescence spectra revealed that 4-aminobenzenesulfonic acid induced conformational change of BSA.

Abstract: The co-doping effect of Si and Mn have been studied in the low temperature grown ferromagnetic semiconductor (Ga,Mn)As thin films. It is found that Si doping decreases the Curie temperatures of the ferromagnetic sample due to carrier compensation and defects formation. The transport studies show that the Si incorporation increases the resistivity of the (Ga,Mn)As thin films, and increase the planar Hall resistance while increases the resistance transitions in the magnetic samples.

Abstract: A simple and convenient method for simultaneous determination of two major effective components (oleic acid and linoleic acid) in Coix seed oil has been developed. The sample was analyzed in a RP-C18 column with acetonitrile: tetrahydrofuran: water (containing 0.4% HAC) (77:3:20, v/v/v) as a mobile phase, and the differential refractive index detector was used in HPLC. The column temperature was fixed at 30°C and the flow rate was 1.0 ml/min. The average recovery rate of oleic acid and linoleic acid are 102.83% and 99.33%, the RSD (n=6) are 1.24% and 2.27%, respectively. The standard curves of oleic acid and linoleic acid presented the favorable linear correlation over the range of 0.098-10.05 mg/ml and 0.101-10.38 mg/ml(R2 >0.999). The method reported in this paper is reliable and relatively simple with a good reproducibility for the determination of oleic acid and linoleic acid in Coix seed oil comparing with the existing methods.

Abstract: The microbial corrosion behaviors of 10CrNiCu steel influenced by Thiobcillus ferrooxidans (T.f) were studied by microbiological, electrochemical and surface analysis method. The open circuit potential (E_ocp) and electrochemical impedance spectroscopy (EIS) of the 10CrNiCu electrodes were measured in immersion electrode way with and without T.f solution at the time of the 0, 2^nd, 7^th, 14^th and 21^st days, respectively. E_ocp of the electrode immersed in sterile medium shifted to negative potential with the immersion time while that for immersion in T.f solutions shifted negatively, then positively and finally negatively. EIS results were interpreted with different equivalent circuits of the electrode/biofilm/solution interface. The result of SEM indicated that, after 21 immersion days, there were different sizes of pits on the 10CrNiCu surface occurred in T.f solution while no evidence of the pitting corrosion was observed on the steel surface immersed in the sterile medium.

Abstract: Using tetraethoxysilane, aluminum nitrate and aluminum fluoride as raw materials, the precursor of mullite was prepared by sol-gel process. When the precursor sintered at 1200°C, mullite ceramic was obtained. Differential thermal analysis, X-ray powder diffraction and scanning electron microscope were used to characterize the dried mullite gel and ceramic blocks. The results suggest mullite is synthesized by solid-phase reaction mechanism. X-ray powder diffraction indicates mullite is the main crystals phase in the ceramic specimen. SEM micrograph shows the mullite grains in the shape of short rod with length of 20 um when sintered at 1200 °C for 2 h and the grains grown up to acicular with length of more than 50 um when the treating time under 1200 °C achieved to 4 h.

Abstract: Some industrial trials of utilizing limestone as a new kind of slag-making agent instead of lime for slagging during LD-steelmaking process are discussed and analyzed in the present work. The results indicate that with oxygen blowing time being unchanged, slag forming rate increased significantly and final steel compositions and temperature reached the required standard during the steelmaking process with limestone used, compared with the process by using lime. The preliminary success achieved from industrial tests gave strong evidence that the idea of using limestone instead of lime for slagging is feasible and this new steelmaking method with limestone used, which saves energy and reduces CO₂ emissions, can be successfully applied into industrial production. Thus, the application of this new method can not only sharply reduce energy consumption and emission of dust and CO₂, but also bring significant environmental and economic benefits.