This article theoretically studies the Bénard-Marangoni instability problem for a liquid layer with a free upper surface, which is heated from below by a heating coil through a solid plate in ana.c. electric field. The boundary effects of the solid plate, which include its thermal conductivity, electric conductivity and thickness, have great influences on the onset of convective instability in the liquid layer. The stability analysis in this study is based on the linear stability theory. The eigenvalue equations obtained from the analysis are solved by using the fourth order Runge-Kutta-Gill's method with the shooting technique. The results indicate that the solid plate with a higher thermal or electric conductivity and a bigger thickness tends to stabilize the system. It is also found that the critical Rayleigh numberRc, the critical Marangoni numberMc, and the criticala.c. Rayleigh numberEac become smaller as the intensity of thea.c. electric field increases. 相似文献
Polyaniline/Na+‐montmorillonite (Na+‐MMT) nanocomposites synthesized by in‐situ intercalative polymerization of aniline into Na+‐MMT are reported. The expansion distribution of basal spacing of the silicate layers upon the increase of the amount of aniline relative to Na+‐MMT is, for the first time, estimated from the square of the full‐width at half‐maximum (FWHM2) of XRD patterns. According to the FT‐IR frequency shift of the C‐N stretching vibration, the change in the basal spacing of the silicate layers is closely related to the degree of hydrogen bonding between polyaniline and the silicate basal surface in a confined geometry. 相似文献
Summary: Shear‐induced phase behavior of poly(ethylene oxide‐b‐(DL ‐lactic acid‐co‐glycolic acid)‐b‐ethylene oxide) (PEO‐PLGA‐PEO) triblock copolymers in water is investigated using rheology and small‐angle neutron scattering equipped with an in situ Couette shear cell. For gels formed by the macroscopic phase separation, the steady shear experiment reveals that the flow‐induced anisotropy on a nanometer length scale at a critical shear rate and the phase separation on a larger length scale are successively induced with a further increase in the shear rate. In particular, the hard gels show a memory effect inscribed by a pre‐high shear in contrast to the soft gels.
2D SANS patterns clearly show the memory effect of the hard gels at a pre‐high shear. 相似文献
A strategy to fabricate nanostructured poly(3‐hexylthiophene) (P3HT) films for organic photovoltaic (OPV) cells by a direct transfer method from a reusable soft replica mold is presented. The flexible polyfluoropolyether (PFPE) replica mold allows low‐pressure and low‐ temperature process condition for the successful transfer of nanostructured P3HT films onto PEDOT/PSS‐coated ITO substrates. To reduce the fabrication cost of masters in large area, we employed well‐ordered anodic aluminum oxide (AAO) as a template. Also, we provide a method to fabricate reversed nanostructures by exploiting the self‐replication of replica molds. The concept of the transfer method in low temperature with a flexible and reusable replica mold obtained from an AAO template will be a firm foundation for a low‐cost fabrication process of ordered OPVs. 相似文献
A series of anchor‐functionalized cyclometalated bis(tridentate) ruthenium(II) triarylamine hybrids [Ru(dbp‐X)(tctpy)]2? [ 2 a ]2?–[ 2 c ]2? (H3tctpy=2,2′;6′,2′′‐terpyridine‐4,4′,4′′‐tricarboxylic acid; dpbH=1,3‐dipyridylbenzene; X=N(4‐C6H4OMe)2 ([ 2 a ]2?), NPh2 ([ 2 b ]2?), N‐carbazolyl [ 2 c ]2?) was synthesized and characterized. All complexes show broad absorption bands in the range 300–700 nm with a maximum at about 545 nm. Methyl esters [Ru(Me3tctpy)(dpb‐X)]+ [ 1 a ]+–[ 1 c ]+ are oxidized to the strongly coupled mixed‐valent species [ 1 a ]2+–[ 1 c ]2+ and the RuIII(aminium) complexes [ 1 a ]3+–[ 1 c ]3+ at comparably low oxidation potentials. Theoretical calculations suggest an increasing spin delocalization between the metal center and the triarylamine unit in the order [ 1 a ]2+<[ 1 b ]2+<[ 1 c ]2+. Solar cells were prepared with the saponified complexes [ 2 a ]2?–[ 2 c ]2? and the reference dye N719 as sensitizers using the I3?/I? couple and [Co(bpy)3]3+/2+ and [Co(ddpd)2]3+/2+ couples as [B(C6F5)4]? salts as electrolytes (bpy=2,2′‐bipyridine; ddpd=N,N′‐dimethyl‐N,N′‐dipyridin‐2‐yl‐pyridine‐2,6‐diamine). Cells with [ 2 c ]2? and I3?/I? electrolyte perform similarly to cells with N719 . In the presence of cobalt electrolytes, all efficiencies are reduced, yet under these conditions [ 2 c ]2? outperforms N719 . 相似文献
We consider the Cauchy problem in Rn for the system of elastic waves with structural damping. We derive (almost) optimal decay rates in time for the L2-norm and the total energy which improves previous results for this system. To derive the estimates for elastic waves, we employ an improvement in a method in the Fourier space, which was developed in our previous works. Our estimates came from those for a generalized energy of α-order in the Fourier space. 相似文献