A weakly compressible MPS method for modeling of open‐boundary free‐surface flow

A mesh‐free particle method, based on the moving particle semi‐implicit (MPS) interaction model, has been developed for the simulation of two‐dimensional open‐boundary free‐surface flows. The incompressibility model in the original MPS has been replaced with a weakly incompressible model. The effect of this replacement on the efficiency and accuracy of the model has been investigated. The new inflow–outflow boundary conditions along with the particle recycling strategy proposed in this study extend the application of the model to open‐boundary problems. The final model is able to simulate open‐boundary free surface flow in cases of large deformation and fragmentation of free surface. The models and proposed algorithms have been validated and applied to sample problems. The results confirm the model's efficiency and accuracy. Copyright © 2009 John Wiley & Sons, Ltd.     

毛细管探针法测定液体表面张力系数的进一步研究

采用较大直径的毛细管对探针法测量液体表面张力系数做了进一步研究.文中引用了Prokhorov提出的改进的瑞利公式,介绍了表面张力系数α的各相关公式的适用范围.实验中利用毛细管探针法测量了几个不同温度下蒸馏水在一直径为5.744.nm的毛细管中的上升高度,用Prokhorov公式计算α.实验测得的蒸馏水的表面张力系数与公认值的百分误差约小于0.13%.最后对实验结果的误差原因进行了分析.     

Investigation on cell biocompatible behaviors of polyaniline film fabricated via electroless surface polymerization

Considering for the potential application in tissue engineering, polyaniline (PANi) film was fabricated via a two-step route: a self-assembled monolayer of C₆H₅NHC₃H₆Si(OMe)₃ was firstly formed on the single-crystal Si substrate; the conducting PANi film was then prepared through electroless surface polymerization of the aniline molecules on the aniline monolayer-bearing silane surface in an acidic aqueous solution. The formation of PANi film on Si surface was confirmed by characterizations of X-ray photoelectron spectroscope (XPS) and specular reflectance Fourier transform infrared (SR-FTIR) spectrum, etc. At last, the proliferation behaviors of PC-12 cells on the PANi film surface were studied by the [3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT) colorimetric assays, acridine orange fluorometric staining, and scanning electron microscope (SEM) observation, etc. The results demonstrate that the as-prepared PANi film provides high ability for cell proliferation, exhibiting promising potentials as surface coating to cultivate neuronal cells for applications in the tissue engineering.     

Photocontrolled extraction of uric acid from biological samples based on photoresponsive surface molecularly imprinted polymer microspheres

We aim to develop novel photoresponsive surface molecularly imprinted polymer (SIMP) microspheres, an SiO₂‐SIMP, for the photocontrolled extraction of uric acid from biological samples. The SiO₂‐SMIP was prepared on silica microspheres by surface polymerization and characterized by using scanning electron microscopy, transmission electron microscopy, FTIR spectroscopy, thermogravimetric analysis, nitrogen adsorption–desorption analysis, and UV‐visible spectroscopy. The SiO₂‐SMIP microspheres showed a photocontrolled uptake and release of uric acid in NaH₂PO₄ buffer upon alternate irradiation at 365 and 440 nm. The SiO₂‐SMIP microspheres were able to photocontrollably extract uric acid from complicated biological samples for concentration analysis with no significant interference encountered and it exhibited very good recognition ability and fast binding kinetics toward uric acid.     

Transient analysis on surface heated piezoelectric semiconductor plate lying on rigid substrate

Based on the thermo-electro-elastic coupling theory, the mathematical model for a surface heated piezoelectric semiconductor (PS) plate is developed in the time domain. Applying the direct and inverse Laplace transformations to the established model, the mechanical and electrical responses are investigated. The comparison between the analytical solution and the finite element method (FEM) is conducted, which illustrates the validity of the derivation. The calculated results show that the maximum values of the mechanical and electrical fields appear at the heating surface. Importantly, the perturbation carriers tend to concentrate in the zone near the heating surface under the given boundary conditions. It can also be observed that the heating induced elastic wave leads to jumps for the electric potential and perturbation carrier density at the wavefront. When the thermal relaxation time is introduced, all the field quantities become smaller because of the thermal lagging effect. Meanwhile, it can be found that the thermal relaxation time can describe the smooth variation at the jump position. Besides, for a plate with P-N junction, the effect of the interface position on the electrical response is studied. The effects of the initial carrier density on the electrical properties are discussed in detail. The conclusions in this article can be the guidance for the design of PS devices serving in thermal environment.     

Two-frequency mutual coherence function and its applications to pulse scattering by random rough surface

An analytic expression of the two-frequency mutual coherence function (MCF) was derived for a two-dimensional random rough surface. The scattered field was calculated by the Kirchhoff approximation, which is valid in the case that the radius of curvature of the surface is much larger than the incident wave length. The scattering problem of narrowband pulse was investigated to simplify the analytic expression of the two-frequency MCF. Numerical simulations show that the two-frequency MCF is greatly dependent on the root-mean-square (RMS) height, while less dependent on the correlation length. The analytic solutions were compared with the results of Monte Carlo simulation to assess the accuracy and computational efficiency. Supported by the National Natural Science Foundation of China (Grant No. 60571058) and the National Defense Foundation of China (Grant No. 51403020505DZ0111)