Advanced Materials Research Vols. 152-153

Abstract: Modified loosestrife powder (MLP), as a new adsorbent, was prepared from dry loosestrife powder by oxidization treatment using peracetic acid with tetrahydrate manganese acetate as catalyst. IR spectra analysis and Boehm titration method were employed to explore MLP’ surface acidic functional groups. Batch adsorption experiments were carried out for the removal of Methylene Blue (MB) from aqueous solution by MLP. Equilibrium experimental data were better represented by Freundlich isotherm using linear methods. Thermodynamic parameters such as G, H and S were also calculated. The results showed that the adsorption of MB onto MLP was efficient and could serve as a promising low-cost adsorbent.

Abstract: A new nanostructure, (2D) nanopetal of SnO2, has been grown on single silicon substrates by Au-Ag alloying catalyst assisted carbothermal evaporation of SnO2. Field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD) and Raman are employed to identify the morphology and structure of the synthesized productions. Room-temperature photoluminescence (PL) is used to characterize the luminescence of SnO2 nanostructure. Three new peaks at 356, 450 and 489 nm in the measured photoluminescence spectra are observed, implying that more luminescence centers exist in SnO2 nanopetals due to nanocrystals and defects. The growth of the SnO2 nanopetals is discussed on the basis of the self-catalyst mechanism.

Abstract: Ethanoligenens sp. R3 isolated from anaerobic sludge in a continuous stirred tank reactor was investigated for its characteristics of fermentative hydrogen production in this study. Effects of initial pH value, fermentation temperature and proportion of carbon/nitrogen source on hydrogen production were investigated in batch experiments. The typical substrate for hydrogen production of glucose and peptone were used as the carbon source and nitrogen source, respectively. The results show that the maximum hydrogen production yield of 834 mlH2/L culture was obtained with initial pH value of 5.5 and fermentation temperature at 35°C. In addition, the maximum average hydrogen production rate of 10.87mmolH2/g cell dry weighth was achieved at the carbon/nitrogen source ratio of 3.3. The degradation efficiency of the glucose used as the carbon source ranged from 91.5% to 95.43% during the conversion of glucose to hydrogen by bacteria Ethanoligenens sp. R3.

Abstract: Dispersion mechanism of polycarboxylate type admixture (PCA) in high volume fly ash (HVFA) concrete was studied by testing fluidity of cement paste, zeta potential of cement grains, the adsorbed amount of PCA on surfaces of cement grains and degree of hydration was quantified by loss on ignition measurements. Properties of HVFA concrete were experimentally validated, and microstructure of HVFA concrete was observed by SEM. Experimental results indicated that a combination of PCAs with long and short backbones may enhance the fluidity and fluidity retention of cement pastes. Fly ash has the ability to compensate electrostatic repulsion of PCA by promoting adsorption-dispersion of PCA to cement minerals and making zeta potential of cement grains more negative. HVFA concrete incorporating combined PCA has excellent workability and appropriate strength. Microstructure of HVFA self-compacting concrete is denser for the modified homogeneous of concrete and a higher degree of hydration of cement achieved in the presence of PCA and fly ash. So combined polycarboxylate based admixture is absolutely necessary for producing high volume fly ash concrete with better workability and durability.

Abstract: In present paper, aluminized explosives with separator inside are detonated by plane wave loads from metal flyer impacts. Four types of aluminized explosives(THAL、H-6、HBX-1、HBX-3) that used widely in warheads are test experimentally in order to obtain the critical thickness of separator(thicknesses L50-50% possibility of detonating). The critical separator thicknesses of detonating four types of aluminized explosives are calculated through statistical method according to experimental data. Stability sequence for these four explosive were determinate according to anti-detonation capability. The experimental results provided reference for the selection of explosive and structural design of warhead.

Abstract: In view of the drawbacks of eccentricity magnification factor formula in current lightweight aggregate concrete code in practice, in this research, according to whole-process theoretical analysis and considering second order moment, sectional curvature, lateral deflection and corresponding eccentricity magnification factor at control section for circular cross-section eccentric compression member under different end moment are derived. By comparing them with experimental results, eccentricity magnification factor calculated in this research are demonstrated to be feasible and reliable, which can provide beneficial reference for structural design in practice.

Abstract: An aligned carbon nanotube（CNT）array has been prepared on large area Ni-deposited silicon substrates via the pyrolysis of C2H2 using thermal chemical vapor deposition technique at 900°C. Ni nanoparticles were formed when Ni catalyst film was etched and conglomerated by NH3 pretreatment. Under the experimental conditions used, scanning electron microscope (SEM) images showed the CNTs films with 3090 nm in diameter and 17 m in length grown perpendicular to the surface of the substrates at an average growth rate of 102 m/h. Energy dispersive X-ray (EDX) spectrum is carried out to identify the composition of the CNTs and EDX analysis demonstrated that the CNTs are formed as tip growth.

Abstract: The semi-solid compression behaviors and the microstructure of Al-Fe alloy prepared by electromagnetic stirred were investigated in the strain rate range of 5×10-3 s-1 to 5×10-1 s-1 and the temperature range of 610 to 640°C on INSTRON-5500R materials testing machine. The experimental results showed that, during the semi-solid deformation of Al-Fe alloy，the peak value of true stress decreased with elevating deformation temperature. As the deformation increased, the stress peak value of the high solid fraction alloy was tending upwards, and that of the low solid fraction was tending downwards. The peak increased with increasing the strain rate. Al-Fe alloy was sensitive to strain rate during semi-solid compression. The strain softening phenomenon would happen. The smaller strain rate, the longer softening process, the stress falling was more slowly. The strain softening was a reason that the semi-solid alloy structure was instability during deformation. The semi-solid deformational behaviors of Al-Fe alloy was bound up with deformation temperature, strain rate, and deforming extent.

Abstract: Tussah silk fibroin (TSF)/hydroxyapatite (HAP) composites were prepared using the co-precipitation method. The results indicate that pure HAP presents needle-like structure with a length of 120-160 nm and a width of 30-40 nm. TSF/HAP composite prepared by adding 8% TSF exhibits a spherical structure, while with the increase of TSF content, the morphology of the composites changed from spherical to short rod, and the length of composite increases from 78 to 146 nm, but the width keep stability. FTIR spectra show the absorption peaks of TSF/HAP composite attributed to the amide and PO43- shift with the addition of TSF, indicating the existence of interaction between HAP and TSF molecules. TSF/HAP composites show a weak crystalline structure, being similar to nano-HAP existed in human bone tissue, thus suggesting that TSF molecules affect the crystallinity of HAP. TG analysis shows that TSF/HAP composite prepared by adding 17.6% TSF contains 11% TSF.

Abstract: The dye – sensitized solar cell (DSSC) is an attractive and promising device for solar cell applications that have been intensively investigated worldwide. DSSC consists of a namo TiO2 film of the photo electrode, dye molecules absorbed on the surface of TiO2 film, an electrolyte layer and a Pt counter electrode. Among these, the nanoporous TiO2 film plays an important role because it can adsorb a large amount of dye molecules which provide electrons. Therefore, the TiO2 film affects the cell performance. In this paper, the characteristics of DSSCs with different TiO2 film thicknesses were studied by using electrochemical impedance spectroscopy(EIS). The impedance component attributed to TiO2|electrolyte interface indicated that the small semicircle and low characteristic frequency was essential for high performance DSSC. An optimum overall conversion efficiency( ％) of 5.54% was obtained in the DSSC assembled with the TiO2 film thickness of 8.86μm.