Sol–Gel SiO2-ZrO2 Coatings for Optical Applications

SiO₂-ZrO₂ based nanostructured multilayers films have been prepared by sol–gel processing from metallorganic precursors by low temperature inorganic polymerization reactions. Simultaneous gelation of both precursors was realized. Homogeneous and transparent films were obtained at room temperature by dip- and spin-coating on glass and silicon wafer substrates. Samples with successively deposited layers (1–3 layers) and successive thermal treatments have been also studied. Each deposited layer was thermally treated for 1 h at 300°C. The coatings were characterized by XRD, spectroellipsometry (SE), UV-VIS spectroscopy and AFM methods. The influence of substrates, number of coatings and number of thermal treatments on the optical and structural properties of the films was established. The thickness of three deposited SiO₂-ZrO₂ layers is about 496 nm on glass substrates and 413 nm on the silicon wafer substrate. The films deposited on glass are more porous than those deposited on silicon. The properties of optical waveguide prepared from SiO₂-ZrO₂ layers on silicon substrates will be discussed.     

The Kodaira dimension of diffeomorphic Kähler threefolds

We provide infinitely many examples of pairs of diffeomorphic, non-simply-connected Kähler manifolds of complex dimension three with different Kodaira dimensions. Also, in any possible Kodaira dimension we find infinitely many pairs of non-deformation equivalent, diffeomorphic Kähler threefolds.

     

The role of surface absorption coefficient in the thermal field of the laser–thin film interaction

In the present paper we developed a model of laser–thin film interaction, in order to find the thermal fields during laser irradiation. The approximation consists in the fact that k (the thermal conductivity) and γ (the thermal diffusivity) are of the same order of magnitude for the substrate and thin film. In consequence we can consider that we have one solid sample with k and γ of the Si substrate. On the other hand we cannot say the same thing about . One can easily see that, _SiCu,Al,Ag,_Au. In consequence we propose an absorption coefficient, as close as possible to reality. In the present paper, we then calculate the thermal fields produced by the surface absorption.     

Synthesis of Hydroxypyrrolone Carboxamides Employing Selectfluor

Reaction of pyrrole‐2‐carboxamides with Selectfluor in MeCN/water (4:1) affords 2‐hydroxy‐5‐oxopyrrole‐2‐carboxamides in yields of up to 80 %. A variety of sensitive functional groups is tolerated, among them aldehydes and alkynes. The new method also works in the presence of allyl groups and appears to be superior to the use of singlet oxygen. Reaction of the monobrominated dihydropyrrolo[1,2‐a]pyrazinone mukanadin C and its nonbrominated analogue afforded bicyclic hydroxypyrrolones. These compounds are interesting as they constitute a partial structure of the marine natural product oxocyclostylidol.     

The role of optimization in some recent advances in data-driven decision-making

Mathematical Programming - In this paper, we present a new framework of bi-level unconstrained minimization for development of accelerated methods in Convex Programming. These methods use...