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11.
Fazle Mabood Giulio Lorenzini Nopparat Pochai Sheikh Muhammad Ibrahim 《Continuum Mechanics and Thermodynamics》2016,28(6):1925-1932
A numerical treatment for axisymmetric flow and heat transfer due to a stretching cylinder under the influence of a uniform magnetic field and prescribed surface heat flux is presented. Numerical results are obtained for dimensionless velocity, temperature, skin friction coefficient and Nusselt number for several values of the suction/injection, magnetic and curvature parameters as well as the Prandtl number. The present study reveals that the controlling parameters have strong effects on the physical quantities of interest. It is seen that the magnetic field enhances the dimensionless temperature inside the thermal boundary layer, whereas it reduces the dimensionless velocity inside the hydrodynamic boundary layer. Heat transfer rate reduces, while the skin friction coefficient increases with magnetic field. 相似文献
12.
Nopparat Thavornsin Pitchaporn Chamrasboon Pongsathorn Kiatmongkolkul Ryo Sakthanasait Mongkol Sukwattanasinitt Sumrit Wacharasindhu 《Journal of polymer science. Part A, Polymer chemistry》2019,57(14):1556-1563
Metal catalyst contamination is a major concern in the preparation of polymeric materials. For conjugate polymers, trace amount of metal catalyst is detrimental to the optoelectronic properties. In this work, a method for synthesizing highly pure fluorescent polymers, poly(aryleneethynylene)s (PAEs), was developed using heterogeneous Pd/CaCO3 catalytic system. Polymerization between a variety of aryl diethynes and aryl diiodides or dibromides were achieved using a catalytic amount of Pd/CaCO3, CuI, and PPh3 at 80 °C in good to excellent yields (79–100%). Resulting polymers possess degree of polymerization ranging from 8 to 50 with polydispersity index of 1.5–3.6. Importantly, PAEs from Pd/CaCO3 catalytic system contain considerably lower level of Pd and Cu contamination (1.9 and 3.4 ppm, respectively) than those obtained from classical homogeneous catalyst, Pd(PPh3)4 and PdCl2(PPh3)2 or heterogeneous catalyst Pd/C. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1556–1563 相似文献