A Hydrodynamic Model for Covalent Semiconductors with Applications to GaN and SiC

In this paper we present a hydrodynamical model which, in principle, is able to describe charge transport in a generic compound semiconductor. The model makes use of an analytic approximation for the conduction bands. Energy dispersion relationships in the neighbors (valleys) of the lowest minima are, in fact, taken to be spherical, nonparabolic. The model considers the main scattering mechanisms in polar semiconductors, that is the acoustic, polar optical, intervalley non-polar optical phonon interactions and the ionized impurity scattering. Simulations are shown for the cases of bulk GaN and SiC.     

High-order Levi curvatures and classification results

In this paper we write some differential formulas involving the high-order Levi curvatures of a real hypersurface in a complex space form. As application we get a classification result under suitable assumptions.     

Nonlinear inviscid damping and shear-buoyancy instability in the two-dimensional Boussinesq equations

We investigate the long-time properties of the two-dimensional inviscid Boussinesq equations near a stably stratified Couette flow, for an initial Gevrey perturbation of size ε. Under the classical Miles-Howard stability condition on the Richardson number, we prove that the system experiences a shear-buoyancy instability: the density variation and velocity undergo an $O(t^{-1/2})$ inviscid damping while the vorticity and density gradient grow as $O(t^{1/2})$. The result holds at least until the natural, nonlinear timescale $t\approx {\epsilon }^{-2}$. Notice that the density behaves very differently from a passive scalar, as can be seen from the inviscid damping and slower gradient growth. The proof relies on several ingredients: (A) a suitable symmetrization that makes the linear terms amenable to energy methods and takes into account the classical Miles-Howard spectral stability condition; (B) a variation of the Fourier time-dependent energy method introduced for the inviscid, homogeneous Couette flow problem developed on a toy model adapted to the Boussinesq equations, that is, tracking the potential nonlinear echo chains in the symmetrized variables despite the vorticity growth.     

Engineered Green Fluorescence Proteins for Proteomics and Biomolecular Electronic Applications

The discovery of the photochromic characteristics of engineered green fluorescent proteins (GFPs) allows new proteomics and biomolecular electronic applications. In particular, photoreversibility among two distinct optical states can lead to the realization of a bio-optical high density storage memory. Here we review our recent work on an optically bistable GFP and we report the recent developments of self-assembly methods for spatial immobilization of proteins into well-definite 2D patterns.     

Thick Coating and Functionalization of Organic Surfaces via ATRP in Water

Atom‐transfer radical polymerization has been used for polymerizing water‐soluble monomers from solid polymeric particles, intended as a model for any polymeric functional surface. Depending on the polarity of substrate and solvent, homogeneous initiation throughout the particles or pure surface initiation could be obtained. In the last case, polymer layers were obtained with thicknesses up to several tens of microns, still active for block copolymerization.