Drop deformation in microconfined shear flow

The deformation and breakup of a drop in an immiscible equiviscous liquid undergoing unbounded shear flow has been extensively investigated in the literature, starting from the pioneering work of Taylor. In this Letter, we address the case of microconfined shear flow, a problem which is relevant for microfluidics and emulsion processing applications. The main effects of confinement include complex oscillating transients and drop stabilization against breakup. In particular, very elongated drop shapes are observed, which would be unstable in the unbounded case and can be explained in terms of wall-induced distortion of the shear flow field. We show that wall effects can be exploited to obtain nearly monodisperse emulsions in microconfined shear flow.     

Stereoselective synthesis of 2-substituted 6-[1-(2,6-difluorophenyl)ethyl]-5-methylpyrimidin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones

A procedure has been proposed for the synthesis of 2-(cyclopentylsulfanyl)-6-[(1R)-1-(2,6-difluorophenyl) ethyl]-5-methylpyrimidin-4(3H)-one through intermediate (3R)-4,4-dimethyl-2-oxotetrahydrofuran-3-yl (2R)-2-(2,6-difluorophenyl)propanoate which was obtained from prochiral 2-(2,6-difluorophenyl)prop-1-en-1-one generated in situ. The proposed procedure may be regarded as stereoselective route to 6-[(1R)-1-(2,6- difluorophenyl)ethyl]-5-methylpyrimidin-4(3H)-one derivatives.     

Superconducting and excitonic quantum phase transitions in doped Dirac electronic systems

We investigate the effect of superconducting and excitonic interactions, as well as their competition, on Dirac electrons on a bipartite planar lattice. It is shown that, at half-filling, Cooper pairs and excitons coexist if the superconducting and excitonic coupling parameters are equal and above a threshold corresponding to a quantum critical point. In the case where only the excitonic interaction is present, we obtain a critical chemical potential, as a function of the interaction strength. Conversely, if only the superconducting interaction is considered, we show that the superconducting gap displays a characteristic dome as charge carriers are doped into the system. We also show that, as the chemical potential increases, superconductivity tends to suppress the excitonic order parameter.     

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