Concordances among electromagnetic, fluid dynamical, and gravitational field theories

We demonstrate mathematical concordances among the theories of electrodynamics, fluid dynamics, and gravitation when the latter two are extended by including a differential geometric structure that we call a vortex field. Experimental data and theoretical arguments for considering such vortex fields in these theories are discussed.     

低温加氢催化剂的设计: 理论与实践

简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性.     

Gold(III) diazonium complexes for electrochemical reductive grafting

Gold(III) diazonium complexes were synthesized for the first time and studied for electrochemical reductive grafting. The diazonium complex [CN-4-C(6)H(4)N≡N]AuCl(4) was synthesized by protonating CN-4-C(6)H(4)NH(2) with chloroauric acid H[AuCl(4)]·3H(2)O to form the ammonium salt [CN-4-C(6)H(4)NH(3)]AuCl(4), which was then oxidized by the one-electron oxidizing agent [NO]PF(6) in CH(3)CN. The highly irreversible reduction potential of 0.1 mM [CN-4-C(6)H(4)N≡N]AuCl(4) observed at -0.06 V versus Ag/AgCl in CH(3)CN/0.1 M [Bu(4)N]PF(6) encompasses both gold(0) deposition and diazonium reduction. Repeated scans showed the absence of the reduction peak on the second run, which indicates that surface modification with a blocking gold aryl film has occurred and is largely complete.     

Simulations of two-phase flow distribution in communicating parallel channels for a PEM fuel cell

Numerical simulations utilizing computational fluid dynamics (CFD) with a volume of fluid (VOF) method has been employed to investigate two-phase flow distribution in inter-connected parallel flow channels. The interconnections resemble gas and liquid communications in fuel cell flow fields due to the inherent or artificial structures of gas diffusion layers (GDLs). The simulation results showed that communication between parallel channels could have a great impact on the two-phase flow pattern, gas and water distribution and flow maldistribution. Wide communication channels provide a pathway for gas to short-circuit the liquid, leading to a worsened gas flow distribution. However, when the communication channels are narrow enough, they are helpful for mitigating the flow maldistribution by redistributing the liquid among the parallel flow channels through the communication channels. The simulation results were also verified by comparing the predicted and measured normalized pressure drop and the gas flow ratios at the entrance section of experimental parallel channels.     

Dynamics of solitons in plasmas for the complex KdV equation with power law nonlinearity

This paper obtains the 1-soliton solution of the complex KdV equation with power law nonlinearity. The solitary wave ansatz is used to carry out the integration. The soliton perturbation theory for this equation is developed and the soliton cooling is observed for bright solitons. Finally, the dark soliton solution is also obtained for this equation.     

High-field QCPMG NMR of large quadrupolar patterns using resistive magnets

Spectroscopy in a high magnetic field reduces second-order quadrupolar shift while increasing chemical shift. It changes the scale between quadrupolar and chemical shift of half-integer quadrupolar spins. The application of QCPMG multiple echo for acquiring large quadrupolar pattern under the high magnetic field of a 25 T resistive magnet is presented for acquiring large quadrupolar patterns. It shows that temporal field fluctuations and spatial homogeneity of the Keck magnet at the NHMFL contribute about ±20 ppm in line broadening. NMR patterns which have breadths of hundreds to thousands of kilohertz can be efficiently recorded using a combination of QCPMG and magnetic field stepping with negligible hindrance from the inhomogeneity and field fluctuations of powered magnets.     

Slope modulation of ring waves governed by two-dimensional sine–Gordon equation

A theory of slope modulation of waves governed by the two-dimensional sine–Gordon equation is proposed. A large time asymptotic solution describing the slope modulation of trains of ring kinks is obtained. The comparison with the numerical solution of two-dimensional sine–Gordon equation shows excellent agreement.     

1-Soliton solution of KdV6 equation

Nonlinear Dynamics - This paper applies three forms of integration tools to integrate KdV6 equation that represents a nonholonomic deformation of the well-known KdV equation, which models...     

1-Soliton solution of the Klein-Gordon-Zakharov equation with power law nonlinearity

This paper obtains the 1-soliton solution of the Klein-Gordon-Zakharov equation with power law nonlinearity. The solutions are obtained both in (1+1) and (1+2) dimensions. The solitary wave Ansatz method is applied to obtain the solution. The numerical simulations are included that supports the analysis.