By using XRD (X-ray diffraction) technique, the microstructure parameters of nanocrystalline brookite-based TiO-2 specimens of various grain sizes are investigated. From the obtained experimental results of the size effect on microstructure, it has been found that there exists a nonmonotonous and anisotropic lattice distortion in the brookite-phase and anatase-phase of these novel nanomaterial TiO-2 crystallites.
A combined experimental and numerical study is undertaken to investigate the hydrodynamic characteristics of single-phase droplet collision in a shear flow. The passing-over motion of interactive droplets is observed, and the underlying hydrodynamic mechanisms are elucidated by the analysis of the motion trajectory, transient droplet deformation and detailed hydrodynamic information (e.g., pressure and flow fields). The results indicate that the hydrodynamic interaction process under shear could be divided into three stages: approaching, colliding, and separating. With the increasing confinement, the interaction time for the passing-over process is shorter and the droplet processes one higher curvature tip and more stretched profile. Furthermore, the lateral separation Δy/R1 exhibits larger decrease in the approaching stage and the thickness of the lubrication film is decreased during the interaction. As the initial lateral separation increases, the maximum trajectory shift by the collision interaction is getting smaller. During the collision between two droplets with different sizes, the amplitude of the deformation oscillation of the larger droplet is decreased by reducing the size ratio of the smaller droplet to the bigger one.
This paper describes a numerical investigation of the groove-embedded droplet dewetting process, namely the spontaneous transition from the Wenzel state to the Cassie state, using the multiphase lattice Boltzmann method. Numerical simulations are employed to reproduce the dynamic behaviors of extension, squeezing, rupture, and ejection of condensation droplets in a groove, allowing us to examine how the groove geometry and wettability affect the dewetting process. Our results identify three dewetting regimes, namely retention, partial dewetting, and complete dewetting. As the groove aspect ratio and hydrophilicity decrease, the dewetting regime changes from retention to partial dewetting, and then to complete dewetting. The partial dewetting and complete dewetting are two effective ways for droplet removing. In particular, a groove sidewall with enhanced hydrophobicity is desirable to stimulate the dewetting process.
Objective To develop an HPLC method for determination of impurities in ephedrine hydrochloride (E) and pseudoephedrine hydrochloride (PE). Methods All of ephedrine alkaloids reference substances and samples were separated with a 20 mmol/L aqueous KH_2PO_4 containing 4% methanol buffer under isocratic elution by using a C_ 18 reversed-phase column within 20 min, and the detection wavelength was 210 nm. Results Six ephedrine alkaloids reference substances were base-line separated and were linear in concentration of selection (R20.999). The relative standard deviation (RSD) of chromatogram area was less than 1.0% for all of them after six successive injections. The detection limit was 0.05 μg/mL for norephedrine (NE), 0.04 μg/mL for norpseudoephedrine (NPE), 0.1 μg/mL for E and PE, and 0.2 μg/mL for mephedrine (ME) and mepseudoephedrine (MPE), respectively (S/N≥3). The recovery rate was more than 97.1% for six ephedrine alkaloids. Under this method system, all of the above-mentioned six samples were tested and found to contain some of the impurity at different levels. Conclusion This developed method, which is very simple, perfect precision, high sensitivity, and selectivity, can be used for the qualitative and quantitative determination of impurities of ephedrine alkaloid-type samples.
Foamed concrete is prepared with sulphate aluminum cement, fly ash, H2O2, FeCl3, calcium stearate and Ce(SO4)2.4H2O in this paper. In the component of foamed concrete, ash is used replacing cement partially (up to 20% by weight), H2O2 and FeCl3 as a foaming agent, as a foam stabilizer and Ce(SO4)2.4H2O as additives. The impact of the content of fly ash, H2O2 and Ce(SO4)2.4H2O on the properties of density and compressive strength of foamed concrete was investigated respectively, as well as the additive of rare earth Ce4+ in the formation of foamed concrete was analyzed. Results of the study show that foamed concrete with the properties of density of 215-320kg/m3 and compressive strength of 0.2-0.65Mpa can be prepared. Ce4+ can be used as foam stabilizer, make shorting the foaming time, improving the foaming ability, and reducing the dry density of the foamed concrete apparently
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