Viscous falling film instability around a vertical moving cylinder

The present work discusses both the linear and nonlinear stability conditions of a viscous falling film down the outer surface of a solid vertical cylinder which moves in the direction of its axis with a constant velocity.After studying the linear conditions,a generalized nonlinear kinematic model is then derived to present the physical system.Applying the boundary conditions,analytical solutions are obtained using the long-wave perturbation method.In the first step,the normal mode method is used to characterize the linear behaviors.In the second step,the nonlinear film flow model is solved by using the method of multiple scales,to obtain Ginzburg-Landau equation.The influence of some physical parameters is discussed in both linear and nonlinear steps of the problem,and the results are displayed in many plots showing the stability criteria in various parameter planes.     

Cyano‐Bridged Trimetallic Coordination Polymer Nanoparticles and Their Thermal Decomposition into Nanoporous Spinel Ferromagnetic Oxides

The synthesis of a novel family of cyano‐bridged trimetallic coordination polymers (CPs) with various compositions and shapes has been reported by changing the compositional ratios of Fe, Co, and Ni species in the reaction system. In order to efficiently control the nucleation rate and the crystal growth, trisodium citrate dihydrate plays an important role as a chelating agent. After the obtained cyano‐bridged trimetallic CPs undergo thermal treatment in air at three different temperatures (250, 350, and 450 °C), nanoporous spinel metal oxides are successfully obtained. Interestingly, the obtained nanoporous metal oxides are composed of small crstalline grains, and the grains are oriented in the same direction, realizing pseudo‐single crystals with nanopores. The resultant nanoporous spinel oxides feature interesting magnetic properties. Cyano‐bridged multimetallic CPs with various sizes and shapes can provide a pathway toward functional nanoporous metal oxides that are not attainable from simple cyano‐bridged CPs containing single metal ions.     

Optical model description of the elastic scattering of 6He from a polarized proton target at 71 MeV/nucleon

The vector analyzing power and differential cross section for the elastic scattering of ⁶He nucleus from polarized protons at 71 MeV/nucleon have been analyzed using the optical model potentials. Different versions of the nuclear potential are constructed using phenomenological potentials and semimicroscopic potentials based upon four different versions of 6He density and three effective nucleon-nucleon interactions. The effects of density dependence and the sensitivity of the cross sections for interactions have been investigated.     

Wilton ripples between two uniform streaming magnetic fluids

An analysis is made of the small-amplitude capillary-gravity waves which occur on the interface of two incompressible inviscid magnetic fluids of different densities. The waves arise as a result of second harmonic resonance. The fluids moving with uniform velocities parallel to their interface are stressed by an oblique magnetic field. The linear relations between the oblique magnetic field and the instability criteria of the linear waves are analyzed. At the stability region (away from the neutral curve) of the linear theory, a pair of coupled non-linear partial differential equations are presented. On the neutral curve, a pair of coupled non-linear partial differential equations are introduced. The last pair of equations may be regarded as the counterparts of the single Klein-Gordon equation which occurs in the non-resonant case. In all cases, the wave profile and its stability conditions are obtained. These conditions are discussed analytically and graphically.     

Controlled Crystallization of Cyano‐Bridged Cu–Pt Coordination Polymers with Two‐Dimensional Morphology

Two‐dimensional (2D) coordination polymers (CPs) have a highly accessible surface area that permits guest molecules to effectively access the micropores in the CPs. Here we report a bottom‐up synthesis of 2D cyano‐bridged Cu–Pt CP nanoflakes using trisodium citrate as a chelating agent, which controls the nucleation rate and the crystal growth. The lateral sizes of the CP nanoflakes are controlled by changing the amount of trisodium citrate used. We strongly believe that our method will be useful for the preparation of other types of 2D CP nanoflakes. The 2D CPs have many active sites for catalytic and electrochemical reactions, and furthermore the assembled CPs can be used as membrane filters.     

Synthesis,characterization, and biocompatibility of poly (acrylic acid/methyl methacrylate)-grafted-poly (ethylene-co-tetrafluoroethylene) film for prosthetic cardiac valves

The surface of poly (ethylene-co-tetrafluoroethylene) (PETFE) strip was grafted by acrylic acid (AAc) and methyl methacrylate (MMA) onto PETFE skeleton to improve the blood compatibility and reduce thrombogenicity for prosthesis. The grafting process was carried out via γ-rays technique as initiator for addition reaction. The optimal conditions were achieved by investigating the effect of different parameters during the grafting process such as exposure to irradiation dose, comonomer concentration, comonomer composition, and solvent. The surface microstructure and composition of copoly (AAc/MMA)-grafted-PETFE surface were characterized by Fourier transform infrared spectroscopy (FTIR), CHNS/O elemental analyzer, scanning electron microscopy (SEM), and electron spectroscopy for chemical analysis (ESCA). Further, heparin was introduced onto the grafted PETFE strip surface. The blood compatibility of modified strip was investigated by the determination of platelet adhesion and thrombus formation. The results indicate that the heparinized copoly (AAc/MMA)-grafted-PETFE sample is a good candidate for manufacturing the prosthetic cardiac valves.