Advanced Materials Research Vols. 233-235

Abstract: The concentration of eight organochlorine pesticides (OCPs) and twelve dioxin-like polychlorinated biphenyls (dl-PCBs) were estimated in nine surface sediment samples from Baihua Lake. Gas chromatography with mass spectrometry (GC-MS) was applied using selected ion monitoring (SIM) mode for the quantification of the OCPs and for the qualification of the dl-PCBs. The results showed that the concentrations of DDTs varied from 1.04 to 36.74 ng g^-1 (dry weight) in these sampling locations, and that of HCHs was in the range from 0.57 to 8.90 ng g^-1. In addition, PCB167 and PCB169 were detected in several sediment samples.

Abstract: A kind of compound catalyst containing the main activate component CuO, the second activate component ZrO₂ and electronic promoter La₂O₃ was prepared. It was applicable to treat with high-concentration dimethyl acetylsuccinate (DMAS) production wastewater with catalytic wet air oxidation technology which was used in continuous bubble columns reactor. In this article the influences of concentration of soaked liquid of every component and the second activate component were studied, and the best preparation condition has been determined. The experimental results indicated that the catalyst of CuO-ZrO₂-La₂O₃/ZSM-5 had a higher activity when handling high-concentration DMAS production wastewater. With this catalyst the COD_cr removal rate could get 98.7% while non-catalyst only 35.8％ at the reaction conditions as follows: reaction temperature 240°C, reaction pressure 3.5MPa, liquor space velocity＝2.0 h^-1, V (oxygen): V（wastewater）＝250:1 and influent wastewater pH=7.

Abstract: Polymer based photonic crystal fibers with low cost manufacturability, and the mechanical and chemical flexibility offer key advantages over traditional silica based photonic crystal fibers. PMMA photonic crystal fiber was fabricated by stacking an array of PMMA capillaries to form a preform, and followed by fusing and drawing into fiber with a draw tower. The air hole diameter and fraction of photonic crystal fiber can be manipulated by the thickness of PMMA capillaries and drawing temperature. The measurement of mechanical properties was performed by universal testing machine. The air core guiding phenomena was observed in air-core PMMA photonic crystal fiber. The ultimate tensile strength of PMMA photonic crystal fiber increases with the increase of the air-hole fraction. The mechanical strengths of all the microstructured optical fibers are higher than those of traditional PMMA fibers. This can be attributed to the introduction of more cellular interfaces which hinder the crack propagation and hence improve the mechanical strength. The plastic extension of PMMA microstructured optical fiber decreases with the increase of the air-hole fraction. Overall, the mechanical flexibility of PMMA microstructured optical fiber is superior than that of traditional PMMA optical fibers.

Abstract: In this paper, the process of Cu-Ag contact wire with adding rare-earth elements was presented. The additive process of the rare-earth elements and the function of the rare earth were chiefly analyzed. Adding the rare-earth elements into melt alloy, the oxide and sulfur can be removed from the liquid, so we can get the purified alloy. At the same time, adding rare-earth can reduce the external crack flaws which produced during the casting and makes the grain refined, as the result, the properties of the Cu-Ag alloy contact wire can be greatly improved and meliorated. Such as the conductivity, the specific elongation, tensile strength and so on, are improved.

Abstract: This article chose three different types of carbon materials as objects, through analyzing the various factors influencing the thermal conductivity; we were to raise the basic mathematical model between the thermal conductivity and graphitization degree. At the same time the correct value in some articles was chosen to establish the corresponding mathematical model of three kinds of carbon materials. After inspection by test results, This model’s relative error was within 7%.The model brought up by this paper has the vital significance to predict the thermal conductivity of the carbon materials and guide the deep application research.

Abstract: α-Fe₂O₃ polyhedrons have been successfully synthesized via a one-pot hydrothermal process. The average diameter of the synthesized α-Fe₂O₃ polyhedrons is about 0.8 μm. The structure and morphology of α-Fe₂O₃ polyhedrons were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. And the possible formation mechanism is proposed that the α-Fe₂O₃ polyhedrons are grown epitaxially from the FeOOH precursors by topotactic transformation. The experimental parameters play a crucial role in the growth of the α-Fe₂O₃ polyhedrons. The results indicate that the phase and morphology of the products are greatly affected by the concentrations of disodium ethyleediamine tetracetate and NaOH in the starting solution. The magnetic properties of α-Fe₂O₃ polyhedrons show weak ferromagnetic behavior with the saturation magnetization of 0.498 emu/g, remanent magnetization of 0.051 emu/g and coercivity of 372.81 Oe.

Abstract: Polyaniline nanoparticle was synthesized via the chemical oxidation of aniline with ammonium persulphate in aqueous hydrochloric acid where the polyaniline particle size obtained was in the range of 22-53 nm. Polyaniline is one type of conducting polymers, where this polymer exhibit high electrical conductivity and have a wide range of interesting application due to its light weight, conductivity and chemical properties. Amongst the family of conducting polymers, polyaniline is unique due to ease of synthesis, environmental stability, simple doping/dedoping chemistry and relatively inexpensive cost. Polyaniline has been used to improve hydrophilic property and permeability of substrate membrane. It is used to obtain superhydrophilic surface because of their high surface energy and hydrophilic property. In this research, these nanoparticles have been used to improve hydrophilic property and permeability of polyethersulfone membrane. The blended membrane was characterized using pure water flux, Scanning Electron Microscope (SEM), and contact angle. As a result, polyaniline can distribute stably in polyaniline membrane to produce stable structure and preferable performance.

Abstract: In this study, a multi-layer blending machine was designed to mix cotton evenly. Being put inside via the feeding port, cotton was spread evenly by the oscillator which moves from left to right back and forth successively. Subsequently, cotton was stored as the multi-layer fibrous cotton in the rear reserve tank. Delivered by the first and the second conveyer belt, the fibrous cotton was sent to the front storage chamber to be cut by a lattice which pulled and dragged the marching cotton vertically. Finally, the processed cotton was rolled out by a striper roller, falling at a certain spot as scheduled, after which spread and blended evenly and thoroughly.

Abstract: This paper mainly discuss the TiO₂ on synthesizing the crystal structure of the cordierite, crystallinity, grain size, sintering properties. Use the software of X 'Pert plus to fit the XRD diagram, analyzing the properties of the crystallization, with the Scherrer formula to calculate the size of the cordierite in the specimen, discussing the TiO₂ on synthesizing the crystal structure of the cordierite, the influence of microcosmic structure and sintering property can be carried out analysis with SEM. The results show that moderate introducing TiO₂ in the process of the cordierite synthesis can easily make the crystal defects, but it can reduce the diffusion resistance of the particle, improve the particle diffusing speed and make the crystallinity of crystallization phase and grain size increase in sample. Due to the radius of the solute ion are greater than the radius of the solvents ion and to some degree the "inflation" function of the clearance of ions can also promotes the volume of the crystal cell. Introduction of excessive TiO₂, the density of the sample and the sintering property is better, but the property of crystallization is declined.

Abstract: The solar photocatalytic degradation of 2,4-dicholrophenol in aqueous solution was carried out direct solar radiation without any collector. A slurry reactor with TiO₂ nanoparticles catalyst was used. The catalyst sample was prepared by sol-gel method from titanium tetra-isopropoxide as raw material and calcinated at 400°C. The photocatalytic activity of TiO₂ nanoparticles were evaluated by photocatalytic degradation of initial concentration (50 mgl^-1) 2,4-dicholrophenol under solar irradiation. The average solar intensity of ultra violet (UV) was recorded as 23 Wm^-2. HPLC was used for monitoring the concentration of 2,4-dicholrophenol in solution at different time intervals during the experiment. The degradation efficiency of 2,4-dicholrophenol removal was 93.8% at pH solution of 6, irradiated for 1 h and using optimum amount of catalyst 2gl^-1 .