A study on electrodeposited of ZnO/ZnS heterostructures

ZnO/ZnS heterostructures were synthesized by a two steps electrochemical deposition method. Firstly, ZnS layer was deposited from an aqueous solution containing Na₂S₂O₃ and ZnSO₄ onto indium-doped tin oxide (ITO) coating glass substrate at two deposition potentials. Then, ZnO nanostructures were deposited from an aqueous solution of Zn(NO₃) onto ZnS surface. The as-obtained samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman and UV-visible analysis. The results indicate that the electrodeposition of ZnS layer at ?0.9 V give the best proprieties of ZnO/ZnS heterostructures. Homogeneous and uniform surface of ZnO/ZnS heterostructure was confirmed by AFM images. The XRD patterns indicates a high crystallinity of ZnO/ZnS. A high transmittance of 65% was also noted from UV-Visible spectra and band gap energy as large as 3.6?eV was found.     

Lesion edge preserved direct average strain estimation for ultrasound elasticity imaging

Elasticity imaging techniques with built-in or regularization-based smoothing feature for ensuring strain continuity are not intelligent enough to prevent distortion or lesion edge blurring while smoothing. This paper proposes a novel approach with built-in lesion edge preservation technique for high quality direct average strain imaging. An edge detection scheme, typically used in diffusion filtering is modified here for lesion edge detection. Based on the extracted edge information, lesion edges are preserved by modifying the strain determining cost function in the direct-average-strain-estimation (DASE) method. The proposed algorithm demonstrates approximately 3.42–4.25 dB improvement in terms of edge-mean-square-error (EMSE) than the other reported regularized or average strain estimation techniques in finite-element-modeling (FEM) simulation with almost no sacrifice in elastographic-signal-to-noise-ratio (SNRe) and elastographic-contrast-to-noise-ratio (CNRe) metrics. The efficacy of the proposed algorithm is also tested for the experimental phantom data and in vivo breast data. The results reveal that the proposed method can generate a high quality strain image delineating the lesion edge more clearly than the other reported strain estimation techniques that have been designed to ensure strain continuity. The computational cost, however, is little higher for the proposed method than the simpler DASE and considerably higher than that of the 2D analytic minimization (AM2D) method.     

Finite element approximation of a prestressed shell model

This work deals with the finite element approximation of a prestressed shell model formulated in Cartesian coordinates system. The considered constrained variational problem is not necessarily positive. Moreover, because of the constraint, it cannot be discretized by conforming finite element methods. A penalized version of the model and its discretization are then proposed. We prove existence and uniqueness results of solutions for the continuous and discrete problems, and we derive optimal a priori error estimates. Numerical tests that validate and illustrate our approach are given.