Advanced Materials Research Vols. 971-973

Abstract: Zinc oxide (ZnO) thin films were prepared by sol-gel spin coating technique, which were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), NKD thin film analysis system and fluorescence spectrophotometer. The results show that ZnO thin films with the each layer thickness of 80 nm present obvious c-axis orientation. With the increase of coating layers, the c-axis orientation characteristic weakens. The reason is considered that the growth mode of ZnO thin films transforms from layer growth to island growth. For the ZnO thin film with 4 layers, it has a compact surface and a uniform particle size of approximately 50 nm, and the photoluminescence (PL) spectrum primarily consists of two PL emission bands, one is a strong and narrow ultraviolet (UV) emission band, another is a weak and broad luminescence emission band from 400 nm to 650 nm. The average transmittance in the visible range is beyond 90%. A optical band gap of 3.26 eV, slightly less than the intrinsic band gap width of 3.37 eV, is obtained by Tauc plotting method. The defects, such as Zn or O vacancies, grain boundaries, are considered to be the main factors causing this situation.

Abstract: A new discrete chemical plume model based on CFD was established, which avoids the shortcomings of the current model. In this model CFD was applied to simulate the turbulent environment of chemical plume, while the chemical substances contained in the plume were modeled as discrete phase. Utilizing this model, chemical plume under water was simulated numerically and analyzed hereafter. The transport characteristics of simulated plume were consistent with existing experimental results. Based on the simulation results, the effect of flow field on plume transport was also analyzed. The model proves an efficient approach to simulate the transport process in different environment, as well as analyze various types of actual situations. Moreover, this model can provide the theoretical basis for plume tracking algorithm research and simulation platform, which promotes significantly the research on chemical plume tracking.

Abstract: It is difficult to obtain precise mathematical model with the traditional methods because of the hysteresis nonlinearity of piezoceramics, and it affects the displacement output accuracy of piezoelectric actuator. The paper proposes an online modeling technique combined with neural network and genetic algorithm (GA). It make the initial parameters of BP neural network be optimized, and so improves the modeling accuracy. Experimental results show that displacement maximum error is 71nm, and the average error is 26nm in the whole trip. It meets the nanopositioning accuracy requirements of piezoelectric staging .

Abstract: Abstract.In this paper, the nonisothermal crystallization kinetics was investigated by differential scanning calorimetry for the poly(m-xylylene adipamide) (MXD6) which were prepared by polymerization in reactor. The Avrami theory modified by Jeziorny and Z.S. Mo equation were used to describe the nonisothermal crystallization kinetics. The analysis based on the Avrami theory modified by Jeziorny shows that the Avrami exponent n of MXD6 ranges from 2.3 to 3.3, Moreover, both Avrami exponent (n) were around 3.0, which probably suggests a thermal nucleation and a three-dimensional crystal growth. The good linearity of the plots indicates the successful application of Z.S. Mo method in this case.

Abstract: Bound solute dialysis in artificial liver support systems is one of approaches to remove protein-bound toxins from patients with liver disease. In this study, a theoretical mass transfer model for bound solute dialysis considering detailed local ultrafiltration was presented. Then, the numerical simulation was performed and the theoretical results were compared with the experimental data in two dialysis modes under various operating conditions, open-loop dialysis mode (OLM) and closed-loop dialysis mode (CLM).Our results show that the theoretical results agree well with the experimental data. The theoretical model presented here can be used to accurately predict the clearance of albumin-bound toxins and optimize the treatment strategy for clinical application.

Abstract: Regional-input high-power laser beam inevitably leads to inhomogeneous and instable temperature distribution of laser milling(LM) process. Knowledge of thermal of multi-track LM is critical to understand the interaction of different milling tracks. Taking into account temperature-dependent thermal conduction and heat capacity, a three-dimensional transient thermal finite element model has been developed. The moving laser beam is simulated with the employment of ANSYS parametric design language and latent heat is considered by using enthalpy. Several conclusions according to the simulation results were produced, comparing with the previous track, the latter one has larger heat affected region and larger in homogeneous temperature distribution; the greatest temperature gradient takes place near the edges of milling part where the scanning direction changes.

Abstract: In this paper, the high quality p-type nitrogen-doped ZnO film was prepared by use of post-treated by plasma-enhanced chemical vapor deposition. The p-type ZnO with the hole density of 2.2×10¹⁶ was obtained. The converting from n-type to p-type was observed, which was obvious on the analysis of the optical and electrical properties of the p-type ZnO. Nitrogen was incorporated into ZnO film during the treatment process to occupy the oxygen positions, and also partly compensated some donor defects. When the amount of activated nitrogen exceeded those donor states to realize an effective compensation, the transformation from n-type to p-type happened.

Abstract: The transition phase and electronic properties of LiBH₄ were investigated by ab initio plane-wave pseudopotential density functional theory method. According to the theoretical calculation, the phase sequence Pnma → P2₁/c → Cc is obtained. The phase transitions Pnma → P2₁/c and P2₁/c → Cc are at the pressure of 1.64 GPa and 2.83 GPa, respectively, by total energy-volume data. As the pressure increases, the value of the band gap energy is reduced from 7.1 (Pnma) to 6.1 eV (Cc). Moreover, the electronic properties of the high pressure phases are discussed. The electronic properties are linked to the band gap energy, total (partly) density of states and atoms (bond) populations.

Abstract: It was reported for the first time that “Turnjujube-like” CdSe nanofibers have been assembled onto TiO₂ surface by electrochemical method of cyclic voltammetry, using CdSO₄•8H₂O and SeO₂ as raw material, can be used as a sensitizer of quantum dot-sensitized solar cell. CdSe morphology, structure characterization and optical properties are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and ultraviolt-visible spectroscopy (UV–Vis), respectively. The experimental results show that the prepared “Turnjujube–like” CdSe nanofibers are zinc blende CdSe with cubic crystal system, and it have excellent light absorption within the wavelength range of 300–800 nm. It has a potential for the construction of QD-sensitized solar energy cell.

Abstract: Guar gum was subjected to degradation in high concentration aqueous solution by enzymatic treating to obtain high concentration low molecular weight guar gum for fracturing. The study indicates that the high concentration guar gum aqueous solution can be degraded effectively by enzymatic treating. The enzymatic treating conditions were investigated and the optical enzymatic treating pH, temperature and enzyme add amount are respectively 6, 50°C and 0.1g/L, and various of low molecular weight guar gum with different molecular weight can be obtained by controlling the enzymatic treating time.