Advanced Materials Research Vols. 774-776

Abstract: In this paper, we report on the preparation and characterization of polyimide (PI) thin films through vapor deposition polymerization (VDP). PI thin films were formed by vapour co-deposition of the precursor monomers pyromellitic dianhydride (PMDA) and 4,4-oxydianiline (ODA) following a thermal treatment at a temperature of over 300°C. The effects of the polymerization temperature on the characterization of PI films were investigated using scanning electron microscopy and Fourier transform infrared spectroscopy. The results showed that the deposited polyamic acid (PAA, a precursor of polyimide) with imidization in the temperature interval of 300-400°C are smooth, uniformly thick and form without shrinkage.

Abstract: With the continuous utilization of resources, the ore characteristics of "poor, fine and complex" emerge continuously, in order to take a comprehensive utilization of resources, it is necessary to match classification. This paper analyzes a copper mine in Shandong province , China, which belongs to the veinlet-disseminated copper ore, with mineral distributes comparison fine, and sulfide ore that is easy to floating content less, this requires the ore should be grinding fine to classification, but not the more fine the better, the sampling experiment studies also confirmed this argument, found that the concentrate recovery of flotation is actually equal to intermediate level rate.

Abstract: The cyclic voltammograms (CVs) of polyacrylonitrile (PAN)-based carbon fibers (CFs) were measured in different electrolyte aqueous solutions, temperatures and concentrations. By analyzing the CVs, the mechanism of the anodic oxidation of PANbased CFs was investigated. The results show that the anodic oxidation of CFs is virtually the activated oxygen formed by oxygen evolution reaction of water reacts with the surface carbon of CFs. Although there are more activated oxygen formed in alkaline electrolytes, surface oxides of CFs are easier to be formed in acidic electrolytes. The higher temperature can make the oxygen evolution reaction of water and surface oxidation of CFs be easier and more violent. The variation in electrolyte concentration can affect intensity of the two reactions, whereas it does not affect the difficulty of the reactions.

Abstract: Electromagnetic property of biological tissue is a critical issue for studying the biological effects of electromagnetic fields. In order to investigate the electrical parameters of rat blood and dispersion spectrum within the low-frequency, dielectric and conductivity parameters of rat blood was measured via HP4275A Multi Frequency LCR Meter in low frequency range (10 kHz-10 MHz), dispersive characteristics of blood electrical parameters was defined within the low-frequency. Dielectric properties of the measurement were used to compare with the theory of Cole-Cole fitting, and the fitting result shows that the Cole-Cole theory can well reflect the dielectric dispersion characteristics of rat blood. These results can be used to studying further biological effects of different frequencies electromagnetic fields.

Abstract: Based on papers collected by Conference Proceedings Citation Index – Science (CPCI-S) database from 1989-2011, this paper investigates and analysis the innovation status and development trends of Nano luminescent materials and devices through the quantitative analysis of paper distribution in the year, the hot R&D field, affiliations and the conference sources in hope of providing an objective statistic reference for future academic researches and innovation development．

Abstract: The light-emission efficiency of InAs/GaAs quantum dots (QDs) affected by proton implantation and subsequent annealing is investigated. The photoluminesce (PL) intensity is determined by the carrier capture time and non-radiative center (NRC) lifetime. The intermixing-induced carrier capture enhancement and the implantation-induced NRC generation mutually compete, so there exists a critical implantation dose (). When is less than , the intermixing is the main effect and the PL intensity increases with . On the other hand, when is larger than , the implantation damage is so large that the intensity decreases with the dose. The higher the annealing temperature is, the larger becomes.

Abstract: Circuiting flow of hot metal is one of reasons for erosion in hearth, which is brought mainly by dead-man in hearth. Studies the influence of different porosity of dead-man to flow of hot metal in the hearth of blast furnace .The results show that:When the porosity of dead-man is reduced,the hot metal on the bottom and the wall of furnace erosion increase.

Abstract: The heat treatment was carried out to modify the aramid fibers, and the effect of tension on the mechanical properties and structure was investigated through Fiber Strength Equipment, viscosity, XRD and SEM . The results show that fibers^，strength slightly decrease, but modulus increase significantly according to the increasing of tension at 480°C and 10s, and reach a maximum when the tension value is 300 g. After heat treatment, molecular weight decrease and the degree of crystallinity increase. SEM show that there is little effect on the surface topography of the fibers during treatment.

Abstract: N-doped and p-doped GaAs nanowires (NWs) are grown on GaAs (111) B substrate using vapor-liquid-solid (VLS) mechanism via a metalorganic chemical vapor deposition (MOCVD) system. It is found that for n-type doped NWs growth rate is proportional the flux rates of dopant and the structure is pure zinc blende without any faults. For p-type doped NWs with large flux rates, there is a critical length, beyond which NWs will be kinked.

Abstract: To investigate the effects of sol pH value and water content on photocatalytic activity of TiO₂ prepared with sol-gel auto-igniting synthesis (SAS) method, TiO(NO₃)₂ was prepared with TiCl₄ as raw material and used as precursor of TiO₂. By changing sol pH value and water content, different TiO₂ powders were prepared and characterized with XRD, SEM and photodegradation of methylene blue (MB). Results indicated that TiO₂ presented the highest photocatalytic activity while sol pH value and mass fraction of water were adjusted to 7 and 50% respectively while the mole ratio of n (TiCl₄): n (citric acid): n (ammonium nitrate) was fixed as 1: 1: 3. The TiO₂ powders were confirmed as loose and porous anatase type with particle size of 15 nm by SEM and XRD.