Advanced Materials Research Vols. 418-420

Abstract: In this paper, europium hydroxide (Eu(OH)₃) was introduced onto multiwall carbon nanotubes (MWCNTs) by the MWCNTs and europium nitrate (Eu(NO₃)₃•6H₂O) on a mild conditions in the alkalescence solution. The influence of the different pH value on the product was analyzed. Characterizations of the products were performed using raman spectroscopy, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution thermal field emission scanning electron microscopy (FE-SEM), and high resolution transmission electron microscopy (HR-TEM). Those results indicated that oxygen-containing groups such as -OH, -C=O, and -COOH generated on the surface of the MWCNTs treated with nitric acid. Those functional groups can attract Eu, and provide the position to Eu(OH)₃. When the pH value situation of the reaction is 7-8, the MWCNTs deposited by Eu(OH)3 were obtained. Furthermore, there is the weak interaction between Eu and the functional groups of the MWCNTs. In addition, the integrity of the MWCNTs was not damaged during the whole preparation.

Abstract: Inhibited and enhanced spontaneous emission of light is essential to quantum optics in design and development of high efficiency optical devices which are useful to security optical communication system. Thus, we performed to develop an efficient single photon source by controlling inhibited or enhanced spontaneous emission of the photon using silicon-based honeycomb lattice patterned finite thickness photonic crystal waveguide. A quantum dot embedded in planar photonic crystal membrane waveguide is the light source. The honeycomb lattice of circular air holes on silicon plate is simulated to obtain large completely photonic band gaps. This significant property shows the potential applied guide modes of photonic crystal membrane for controlling inhibited or enhanced spontaneous emission between the quantum dots and the photonic crystal waveguide. Significantly, this work is oriented to produce the novel single photon sources which can emit one photon at a time for the quantum optical security network with single photon state. In addition to the honeycomb lattice can easily be made on a Si on insulator (SOI) wafer.

Abstract: Due to many different characteristics such as irregular polygon particle with pointed edges, rough surface and larger content of stone powder, machine-made sand has ignorable effects on the properties of concrete. As the basis for the design of concrete structures, the relations among the basic mechanical properties of concrete such as compressive strength, tensile strength, flexural strength and elastic modulus should be clearly understood. This paper summarizes the test data from the published references, and discusses the relations among these properties by statistical analyses compared with those of ordinary concrete. The results show that the axial compressive strength and the tensile strength can be prospected by the same formulas of ordinary concrete specified in current Chinese design code, but the prospected tensile strength should multiply a reducing coefficient when the strength grade of concrete is lower than C30. The elastic modulus of concrete with machine-made sand is larger than that of ordinary concrete, which should be prospect by the formula in this paper. Meanwhile, the formula of flexural strength is suggested.

Abstract: Ethylene Vinyl Acetate (EVA) as package material is widely used in solar cells modules. Conventionally, it is laminated on both sides of solar cells with a planar surface profile, which will lead to high reflectance when the light incident angle is larger than 60°. We proposed a 1-dimensional triangular surface profile of EVA on solar cell modules with base angle about 43°. The investigations show that a 9.9% efficiency improvement of solar cells can be obtained by reducing its surface reflectance.

Abstract: The corrosion behavior of reinforcing bar HRB400 in simulated concrete solution (0.5 wt.% NaCl solution) was investigated, and its tensile mechanical properties were tested before and after corrosion. The results show that, with the increase of corrosion time from 240h to 720h, the corrosion rate increases and the corrosion becomes heavier and heavier, and the composition amounts of corrosion scale are similar. After 720h, the yield strength and tensile strength are decreased by less than 10%, and the elongation are decreased by more than 20%.

Abstract: Tribological behaviors and wear process of the unfilled and 2% nano-serpentine filled polymer-based hybrid PTFE/Kevlar fabric composites were evaluated on a MMU-5G friction and wear tester. The variation of the morphologies of the worn surface and the morphologies of transfer film during the wear processes of the two composites were observed and analyzed by means of the confocal laser scanning microscope (CLSM). The results show that the addition of nano-serpentine can effectively slow down the wear process and obviously improve the wear resistance of the hybrid PTFE/Kevlar fabric composite, meanwhile the friction property was ameliorative. That probably because the nano-serpentine does not only have the admirable tribological performance, but also have excellent surface activity, which improved the formation of the self-lubricating transfer film.

Abstract: Nanostructured Pt thin films were electrodeposited in the presence of varying amounts of xanhtine. The electrodeposited Pt films exhibit different catalytic efficiency for methanol electro-oxidation. The anodic current of methanol decreases linearly with the increase of xanthine during the electrodeposition. The effect of xanthine on the catalytic efficiency of Pt films was studied by cyclic votlammetry (CV) and differential pulse voltammetry (DPV). The results of CV and DPV reveal the formation of a 2:1 complex between Pt(IV) and xanthine. The conditional stability constant of the complexes was determined to be 3.8×10⁶.

Abstract: The insulating brick is prepared used low grade quartz sand along the Yangtze River, and the mechanism of porous structure contolment is researched, which lay technological foundation for increasing the performance of insulating brick. The results show the porosity of unfired porous quartz bricks is decreased with increasing the content of quartz sands. When the content of foaming agent is beyond 0.5%, the porosity of unfired porous bricks is increased with increasing the content of foaming agent. When the ratio of materials and water is above 1:1.1, the porosity of unfired porous bricks is decreased with increasing the content of adding water. Through optimizing the technology that using 60% quartz sands, 39% cement, 1% foaming agent and the ratio of materials and water for 1:1.1 are mixed, the unfired porous quartz bricks is produced, the density is 0.628 g/cm3, the porosity is 74.586% and the compression strength is 1.9 MPa, the porous structure of brick is homogeneous distribution, the pore is closed pore.

Abstract: In this study, polyvinylidene fluoride/liquid crystal polymer (PVDF/LCP) blending membranes were prepared via phase-inversion. LCP is ethyl cellulose (EC) dissolved into acrylic acid (AA). The properties of these blends were measured by differential scanning calorimeter (DSC) and polarizing microscope. The results indicate that LCP formed at the concentration of 0.60g/ml and the blends begin to be observed the presence of liquid crystal. Moreover, at a certain temperature range, higher temperature can quicken the formation of liquid crystal. With the adding of LCP, the cholesteric liquid crystal can be still retained in the blending membranes, but the solution enthalpy decreased.

Abstract: Fly ash (FA) is always used as the pulverized admixture of concrete with machine-made sand to improve the bad workability of fresh concrete such as lower flowing and serious bleeding. According to the specification of Chinese standard, there are three ways of admixing FA into concrete including the additional admixing, the equal-mass replacing cement and the over-mass replacing cement. This paper researches the possibility for unifying these three ways in the mix proportion design of concrete with machine-made sand by fitting the test data with the formula of water to cement ratio. The regression coefficients are given out corresponding to these three ways, the influences of FA on concrete are discussed. The issues in current mix proportion design methods are pointed out. To efficiently play the function of FA as the beneficial admixture of concrete, the activity of FA should be considered as a key factor in the mix proportion design of concrete.