Vibrational spectroscopic studies on crystallisation of sol-gel derived thin films of calcia-alumina binary compound

An optimized sol-gel process has been developed to produce homogeneous thin films of calcium aluminate binary (12CaO·7Al2O3) compound, on magnesium oxide substrates via spin coating. Fourier transform infrared and Raman spectroscopies have been employed to investigate the effect of annealing temperature and duration on the phase transformations in the films. Heat treatment at 1,300 °C under air atmosphere for 2 h produced single-phase 12CaO·7Al2O3 films. However, annealing at a lower temperature of 1,100 °C in air for a period of 4 h in total resulted in the crystallization of 5CaO·3Al2O3 rather than 12CaO·7Al2O3. The X-ray photoelectron spectrum of the thin film annealed at 1,300 °C corresponds to the binding energies of C12A7 compound. The annealing temperature of 1,300 °C for 2 h is found to be sufficient for formulating single phase calcia-alumina binary films in correct stoichiometric ratio of 12:7. © 2014 Springer Science+Business Media New York

Matrix diagonalization and exact solution of the k-photon Jaynes-Cummings model

We study and exactly solve the two-photon and k-photon Jaynes-Cummings models by using a novelty algebraic method. This algebraic method is based on the Pauli matrices realization and the tilting transformation of the $SU(2)$ group and let us diagonalize the Hamiltonian of these models by properly choosing the coherent state parameters of the transformation. Finally, we explicitly obtain the energy spectrum and eigenfunctions for each model.Comment: 12 page

Selecting fast folding proteins by their rate of convergence

We propose a general method for predicting potentially good folders from a given number of amino acid sequences. Our approach is based on the calculation of the rate of convergence of each amino acid chain towards the native structure using only the very initial parts of the dynamical trajectories. It does not require any preliminary knowledge of the native state and can be applied to different kinds of models, including atomistic descriptions. We tested the method within both the lattice and off-lattice model frameworks and obtained several so far unknown good folders. The unbiased algorithm also allows to determine the optimal folding temperature and takes at least 3--4 orders of magnitude less time steps than those needed to compute folding times

Functional Entities -and that ain't the half of it!

Like many other languages, Spanish may specify fractionary nouns with definite articles (cf. la mitad). This fact seems to violate the presupposition of uniqueness generally assigned to the definite article, as no fraction may exist without another one (halves, in particular, come in pairs). But this violation is only apparent-at least if we assume that these fractionary nouns denote fractioning operations (rather than the results thereof) and occur in partitive (rather than attributive) constructions. These proposals can be justified independently, and extend to numeral noun constructions that did not survive into Contemporary Spanish

Binomial Ideals and Congruences on Nn

Producción CientíficaA congruence on Nn is an equivalence relation on Nn that is compatible with the additive structure. If k is a field, and I is a binomial ideal in k[X1,…,Xn] (that is, an ideal generated by polynomials with at most two terms), then I induces a congruence on Nn by declaring u and v to be equivalent if there is a linear combination with nonzero coefficients of Xu and Xv that belongs to I. While every congruence on Nn arises this way, this is not a one-to-one correspondence, as many binomial ideals may induce the same congruence. Nevertheless, the link between a binomial ideal and its corresponding congruence is strong, and one may think of congruences as the underlying combinatorial structures of binomial ideals. In the current literature, the theories of binomial ideals and congruences on Nn are developed separately. The aim of this survey paper is to provide a detailed parallel exposition, that provides algebraic intuition for the combinatorial analysis of congruences. For the elaboration of this survey paper, we followed mainly (Kahle and Miller Algebra Number Theory 8(6):1297–1364, 2014) with an eye on Eisenbud and Sturmfels (Duke Math J 84(1):1–45, 1996) and Ojeda and Piedra Sánchez (J Symbolic Comput 30(4):383–400, 2000).National Science Foundation (grant DMS-1500832)Ministerio de Economía, Industria y Competitividad (project MTM2015-65764-C3-1)Junta de Extremadura (grupo de investigación FQM-024

The morphodynamic responses of artificial embayed beaches to storm events

The morphological changes caused by storm events in two Barcelona beaches were recorded using video monitoring techniques during the period 2001–2006. Changes in shoreline position and configuration and submerged bar position and shape were analyzed during the 25 major storm events that occurred during the study period. Beach responses to storms were grouped into three categories: shoreline advance or retreat (including rotation), sandbar migration and/or configuration change (linear or crescentic shape) and formation of megacusps. This work provides examples of the differential adaptation of both beaches to the same storm and of some unexpected morphological responses of both beaches. The response of the beach to storm events is not straightforward because wave conditions are not the only relevant parameter to be considered. In particular, in such embayed beaches it is crucial to take into account their specific morphodynamic configuration prior to the storm

Wear and friction of TiAlN/VN coatings against Al2O3 in air at room and elevated temperatures

TiAlN/VN multilayer coatings exhibit excellent dry sliding wear resistance and low friction coefficient, reported to be associated with the formation of self-lubricating V2O5. To investigate this hypothesis, dry sliding ball-on-disc wear tests of TiAlN/VN coatings on flat stainless steel substrates were undertaken against Al2O3 at 25 C, 300 C and 635 C in air. The coating exhibited increased wear rate with temperature. The friction coefficient was 0.53 at 25 C, which increased to 1.03 at 300 C and decreased to 0.46 at 635 C. Detailed investigation of the worn surfaces was undertaken using site-specific transmission electron microscopy (TEM) via focused ion beam (FIB) microscopy, along with Fourier transform infrared (FTIR) and Raman spectroscopy. Microstructure and tribo-induced chemical reactions at these temperatures were correlated with the coating’s wear and friction behaviour. The friction behaviour at room temperature is attributed to the presence of a thin hydrated tribofilm and the presence of V2O5 at high temperature