Abstract: A novel liquid crystal monomer 1, 4-Di-[4-(3-acryloyloxyhexyloxy) benzoyloxy]-2-methyl benzene (LCM) was synthesized and characterized by 1H NMR, differential scanning calorimetry (DSC) and polarized optical microscopy (POM). LCM possesses liquid crystal phase between 68 to 124 °C. A f-ast response polymer stabilized cholesteric texture (PSCT) film was prepared based on LCM, and t-he response time was less than 1 ms, which can be applied in true 3D display. In addition, the morp-hology of the polymer network was investigated by scanning electron microscope (SEM).
Abstract: We investigate the effect of carrier dynamics on the temperature dependence of photoluminescence spectra from InAs/GaAs quantum dot heterostructures with different dot size uniformity. Intersublevel relaxation lifetimes and carrier transferring mechanisms are simulated using a model based on carriers relaxing and thermal emission of each discrete energy level in the quantum dot system. Calculated relaxation lifetimes are decreasing with temperature and have larger values for sample with lower dot size uniformity. In the quantitative discussion of carrier dynamics, the influence of thermal redistribution on carriers relaxing process of quantum dot system is demonstrated by our model.
Abstract: Highly ordered Ni-Ag alloy nanowire arrays have been fabricated successfully by electrodeposition into the pores of anodic aluminum oxide (AAO). This template was prepared with modified two-step anodizing method. The scanning and transmission electron microscopy were utilized to characterize the Ni-Ag alloy nanowire arrays. The results revealed that the nanowire arrays were regularly arranged, about 90nm in diameter and 30µm in length. The nanowires were single crystal and the atomic ratio of Ni and Ag is very close to 79:21. Magnetic hysteresis loop showed that Ni-Ag alloy nanowire arrays embedded in AAO have superparamagnetism, indicating their potential applications in biomedical materials.
Abstract: In this work, silver nanoparticles (AgNPs) were successfully synthesized from AgNO3 through a simple and eco-friendly method, also called the green synthesis, using Mon Thong durian (Durio zibethinus L.) peeling extract. The main role in synthesis mechanism of AgNPs is using polysaccharides in durian rind as a reducing agent as well as stabilizer. The appearance of a yellowish-brown color in mixture of AgNO3 solution and durian rind extract is the indication of formation of AgNPs. The synthesized AgNPs were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) spectrometry. The AgNPs were found to be polycrystalline in nature and spherical particles with diameter of 11.7 ± 3.2 nm. The crystallinity with fcc phase is evidenced by clear lattice fringes in SAED pattern and diffraction peaks in the XRD pattern corresponding to the (111), (200), (220), and (311) planes.
Abstract: In this paper, we evaluated the spectra parameters of Er3+.The absorption spectra of Er3+:CaF2 transparent ceramic was measured at room temperature (RT). Based on the Judd–Ofelt theory, the intensity parameters were Ω2= 5.02×10−20 cm2, Ω4 = 3.40×10−20 cm2 and Ω6 = 0.38×10−20 cm2, and then the values of the radiative transition probabilities, radiative lifetimes and integrated emission cross-sections of excited states were calculated. Full width at half maximum (FWHM) of the fluorescence spectra for 4I13/2→4I15/2 transition was investigated, being 17nm. The decay time was found to be 24.3ms, which is longer than the theoretically calculated value indicating a radiation trapping effect in this work.
Abstract: Nitrogen-doped TiO2 nanoparticles of commercial Degussa P25 have been prepared via a direct impregnation reaction using ammonium hydroxide solution as nitrogen source. The Samples were characterized by X-ray diffraction (XRD), BET surface area BJH pore charecterization and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDX). The results demonstrated that the nitrogen-doped TiO2 nanoparticles had a crystallite size 70.8 nm and a specific surface area of 6.4 m2/g with average pore diameter of 23.3 nm consisting mainly of titanium and oxygen. The photocatalyst activity was determined by degradation of phenol in an impinging stream reactor under visible light irradiation (λ> 400 nm). N-TiO2 catalyst exhibited higher photocatalytic activity in comparison with Degussa P25 under visible light irradiation.
Abstract: A series of Cu-Fe/TiO2 photocatalysts were prepared and calcined at 400°C and 500°C for 1 h. The photocatalysts were characterized using diffuse reflectance spectroscopy (DR-UV-Vis), X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The performance for sulfur removal was carried out using model oil containing 100 ppm S (from dibenzothiophene). The highly dispersed Cu-Fe/TiO2 photocatalyst displayed mainly spherical shaped particles. The best performing photocatalyst was 0.8wt% Cu-Fe loading and calcined at 400°C (0.8wt400) giving 18% sulfur removal. The band gap for 0.8wt400 was lowered to 2.96 eV compared to 3.21 eV for TiO2.
Abstract: A laboratory study was carried out to investigate the ability of neutralization of red mud(RM) using carbon dioxide gas at ambient conditions. It was to evaluate the removal of alkali in the red mud using CO2.The neutralized red mud was characterized by X-ray diffraction(XRD) , FP-640 flame photometer and auto titration method. XRD patterns of red mud revealed that the intensity of sodalite was decreased by using CO2. The pH of red mud was decreased from 11 to 8 . The specific advantages of these processes are that, through adding with hydrochloric acid(HCl) and N-Methyldiethanolamine(MDEA), the removal of alkali in the red mud (Na2O) was decreased from 12.5% to 2.3% by adding with HCl.What is more , the removal ratio of sodium oxide in the red mud by adding with HCl can be received at 80%.
Abstract: A polyacrylamide-grafted starch (St-g-PAM) flocculant for the coal slurry wastewater, was prepared by using corn starch and acrylamide (AM) as monomers through solution polymerization. The structure of the synthesized St-g-PAM was characterized by FT-IR and TG. The effects of initiator concentration, reaction temperature, and monomer concentration on percentage of grafting and the grafting efficiency were investigated. The results show that the optimal conditions of the polymerization are as follows: the monomer to substrate ratio of 2.5, potassium persulfate of 0.08 g/mL, reaction time of 3h, the reaction temperature of 65°C. The additional dosage of St-g-PAM is varying between 35 and 45 mg/L to obtain good flocculation capability, better flocculation capability with the addition of 30mg/L of FeCl3.