氯化2,3,5-三苯基-2 氢-四唑(TTC)及2,4,6-三(2-吡啶基)-s -三嗪(TPT)在1mol/L HCl 中对Q235碳钢的缓蚀作用及机理的研究(Ⅱ)

通过X射线光电子能谱(XPS)、椭圆偏振原位测试考察了氯化2,3,5-三苯基-2H-四唑(TTC), 2,4,6-三(2-吡啶基)-s-三嗪(TPT)分子在1 mol/L HCl中对碳钢表面的缓蚀作用, 并从微观上对二者的缓蚀机理进行探讨. XPS测试结果显示, 由C, N元素的1s特征峰产生的化学位移及其积分峰面积表明TTC, TPT分子在金属表面产生了有效抑制腐蚀的保护层; 由椭圆偏振原位测试并结合动电位极化曲线测试,考察了TTC, TPT分子对金属表面腐蚀反应的抑制程度, 并得到了相位差等参量, 结果表明二者在金属表面形成了具有缓蚀作用的覆盖层.     

Protein adsorption and cell adhesion on polyurethane/Pluronic® surface with lotus leaf-like topography

Lotus leaf-like polyurethane/Pluronic^® F-127 surface was fabricated via replica molding using a natural lotus leaf as the template. Water contact angle measurements showed that both the hydrophobicity of the unmodified polyurethane (PU) surface and the hydrophilicity of the PU/Pluronic^® surface were enhanced by the construction of lotus leaf-like topography. Protein adsorption on the PU/Pluronic^® surface without topographic modification was significantly lower than on the PU surface. Adsorption was further reduced when lotus leaf-like topography was constructed on the PU/Pluronic^® surface. Cell culture experiments with L929 cells showed that adhesion on the PU/Pluronic^® surface with lotus leaf-like topography was low and adherent cells were spherical and of low viability. The PU/Pluronic^® surface with lotus leaf-like topography thus appears to be resistant to nonspecific protein adsorption and to cell adhesion, and these effects derive from the both chemical composition and topography. The results suggest a new strategy based on surface topography for the design of antifouling materials.     

Ta2O5 templated growth of droplet-like platinum particles by potentiodynamic polarization of tantalum in aqueous solution of hexachloroplatinic acid

By potentiodynamic polarization of mechanically polished tantalum in a diluted aqueous solution of hexachloroplatinic acid, droplet-like platinum microparticles were electrodeposited, embedded into the simultaneously formed Ta₂O₅ film. The roughness factor of platinum of 31 was achieved. Within the potential region of both hydrogen and oxygen underpotential deposition, in both acidic and alkaline solutions, the composite Pt/Ta₂O₅ electrode displayed an excellent electrochemical response characteristic of smooth polycrystalline platinum. The preparation method applied in this work presents an easy way to obtain an electrode surface combining the behaviour of smooth polycrystalline platinum with the behaviour of microdisc arrays. Its electrocatalytic effectiveness was demonstrated for an oxygen reduction reaction in alkaline solutions.     

A kind of new algebraic Rossby solitary waves generated by periodic external source

In the article, by employing multiple-scale, perturbation method, a new model is derived to describe the algebraic Rossby solitary waves generated by periodic external source in stratified fluid. The local conservation laws and analytic solutions of the model are obtained, and the breakup properties are discussed. By numeric simulation, some problems on the generation and evolution of the algebraic solitary waves under the influence of periodic external source are theoretically investigated. The results show that besides the solitary waves, an additional harmonic wave appears in the region of the external source forcing. Furthermore, the periodic variation of the external source forcing can prevent solitary waves from breaking. Meanwhile, the detuning parameter has an important effect on the breakup of the algebraic Rossby solitary waves.     

Angle-resolved time-of-flight spectra of neutral particles desorbed from laser irradiated CdS

Angle-resolved time-of-flight spectra of neutral particles desorbed from laser irradiated CdS have been investigated with a pulse mass counting method. Three quantities to characterize the desorption dynamics — the desorption flux, the mean kinetic energy and the speed ratio — depend remarkably on the incident laser power and the ejection polar angle θ. The desorption flux is strongly peaked forward deviating from the cosine distribution. For low laser power, the desorbing S₂ follows the same Maxwellian velocity distribution over the polar angles below 50°. For high laser power, the Maxwell distribution is limited to a narrow cone around the polar axis and with increasing polar angle the spectra of the velocity distribution become broader than the simulated Maxwellian one. With increasing laser power the mean kinetic energy increases for gq < 40°, while for θ > 40° it decreases abnormally. For these apparent breakdowns of the Maxwell law and Knudsen law, the dynamic behaviour of desorbing particles obeys a non-equilibrium thermal mechanism, which may involve a solid-gas phase transformation.     

Studies of defect structure effects on the transport properties of pure crystalline n-CdS VIA the temperature dependence of photoacoustic and photocurrent spectra

Microphone gas-coupled photoacoustic spectroscopy (PAS) and photocurrent spectroscopy (PCS) have been applied simultaneously to pure high resistivity single crystals of n-CdS at room and low temperatures. The PA and PC spectra obtained at open-circuit and with an applied AC or DC transverse electric field were consistent with an enhancement of the non-radiative recombination quantum efficiency at subbandgap wavelengths at room temperature, accompanied by increasing domination of the open circuit PA spectrum by this parameter at lower temperatures. Further evidence of the importance of non-radiative carrier recombinations at intrabandgap defect centers in the generation of the PA and PC signals was obtained upon introducting deliberate mechanical damage to a single crystal of CdS. The PA technique was found to have an advantage over PC spectroscopy in its ability to spectrally resolve completely the observed peaks attributed to the intrinsic band-to-band transition and to the wavelength dependence of the non-radiative quantum yield.     

An approximate solution for the bending vibrations of a combination of rectangular thin plates

The appropriate method often used for calculating the bending vibration of a single rectangular plate is extended to calculate the bending vibrations of a global system of combinations of rectangular plates with elastically supported and damped non-coupled edges. Two examples, a series of T-combinations and an L-combination of rectangular thin isotropic plates, are considered and the input and transfer mobilities due to point excitation derived. Numerical results are presented for the case of combinations of concrete plates and the effects of varying the material damping of the plates and edge damping are investigated.The eigenfrequencies of an L-combination of plates with one plate of very high bending stiffness are calculated and results compare well with the eigenfrequencies of a single plate calculated by means of the classical Ritz-Rayleigh method.