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145 results on '"Silla, E."'

1. Aislamiento acústico a ruido aéreo en acristalamientos de vidrio

Author

Escuder Silla, E., Alba Fernández, J., and Ramis Soriano, J.

Subjects
Glazing systems, Airborne Sound Insulation, prediction, Acristalamientos de vidrio monolítico y laminado, aislamiento acústico, prediccion, Clay industries. Ceramics. Glass, TP785-869
Abstract

In this paper, the Ookura & Saito model is applied to determine the Airborne Sound Insulation of glazing systems. In particular, the calculations that appear are for monolithic glasses of different thicknesses and laminated glasses from different types. There are different prediction models of the airborne acoustic behaviour of multilayer panels (and the laminated glasses can be considered like such). In all of them, the input data are the elastic constants and the loss factor. The monolithic glasses and the intermediate layer have been characterized according to different Standards. The results are compared with experimental measurements and data of the study of Marsh (1), obtaining a range of acceptable adjustment.En este artículo se aplica el modelo de Ookura & Saito para determinar el aislamiento acústico a ruido aéreo de sistemas constructivos basados en vidrios. En concreto, los cálculos que se presentan son para vidrios monolíticos de distintos espesores y para vidrios laminados de diferentes tipos. Existen diferentes modelos de predicción del comportamiento acústico a ruido aéreo de estructuras multicapa (y los vidrios laminados pueden considerarse como tales). En todos ellos, los datos de entrada son las constantes elásticas y el factor de pérdidas. Tanto los vidrios monolíticos como la capa intermedia se han caracterizado siguiendo diferentes normativas. Los resultados se comparan con medidas experimentales y con datos recogidos del estudio de Marsh (1), obteniéndose un grado de ajuste aceptable.

Published
2007

6. Amino acid chemistry in solution: structural study and vibrational dynamics of glutamine in solution. An ab initio reaction field model

Author

Ramirez, F.J., Silla, E., and Tunon, I.

Subjects
Amino acids -- Research, Glutamine -- Research, Vibrational spectra -- Research, Chemicals, plastics and rubber industries
Abstract

A study was conducted to analyze structural and vibrational properties of the amino acid L-glutamine in solution using self-consistent reaction field theory. The aqueous solutions were made by utilizing tridistilled water and deuterium oxide. The Jobin Yvon Ramanor was utilized to record the Raman spectra of the solutions. Experimental results indicated that structural parameters and vibrational frequencies correlated with experimental data.

Published
1998

15. HCnN: the largest molecules in the interstellar medium

Author

Arnau, A., Tunon, I., Silla, E., and Andres, J.M.

Subjects
Interstellar matter -- History, Cosmochemistry -- Analysis, Interstellar molecules -- History, Chemistry, Education, Science and technology
Published
1990

21. Vibrational dynamics of histamine monocation in solution: an experimental (FT-IR, FT-Raman) and theoretical (SCRF-DFT) study

Author

Collado, J.A., Tunon, I., Silla, E., and Ramirez, F.J.

Subjects
Cations -- Research, Density functionals -- Usage, Fourier transform infrared spectroscopy -- Usage, Histamine -- Research, Raman spectroscopy -- Usage, Chemicals, plastics and rubber industries
Abstract

Issues concerning the vibrational dynamics of histamine in solution, at physiological pH, are discussed. It is concluded that solute-solvent interactions must be taken into consideration when seeking to understand the vibrational behaviour of polar species in solution.

Published
2000

37. Empirical equations for sound propagation in different sound absorbent materials.

Author

Alba Fernández, J., Ramis Soriano, J., Sanchis, E. Juliá, and Escuder Silla, E.

Subjects
ABSORPTION of sound, ACOUSTICAL materials, ACOUSTICAL engineering, FIBROUS composites, TEXTILE fibers, SOUND measurement, ACOUSTIC impedance, STRENGTH of materials
Abstract

There are many different types of sound absorbent materials. Nowadays, some simple models are used to characterize these materials. These models are based on empirical equations obtained from measured data. The models are only valid for the studied materials. In the references there are different empirical models to predict the behaviour of some materials. In this investigation, a study of the behaviour of these simple models has been carried out, and some empirical equations for several sound absorbent materials have been proposed. [ABSTRACT FROM AUTHOR]

Published
2007

42. A QM/MM Study of the Conformational Equilibria in the Chorismate Mutase Active Site. The Role of the Enzymatic Deformation Energy Contribution

Author

Marti, S., Andres, J., Moliner, V., Silla, E., Tunon, I., and Bertran, J.

Abstract

A conformational structures search of chorismate mutase substrate has been carried out using in vacuo AM1 and MP2/6-31G* methods and by means of a hybrid quantum mechanical/molecular mechanical (QM/MM) procedure in the solvated enzyme. Apart from the pseudodiequatorial and pseudodiaxial conformers of chorismate reported in the literature, new structures have been located using both methodologies. A comparative analysis of the results reveals the importance of the mechanical and electronic constraints imposed by the enzyme in this preequilibrium. These specific interactions between the substrate and the enzyme environment change the order of stability of the different conformers obtained in vacuo, thus stabilizing those structures that can be considered as the precursor for the rearrangement of chorismate to prephenate. The deformation energy of the enzyme to mold the substrate into the active site appears as the major factor in the energetic ordering of all the studied conformers.

Published
2000

45. Intramolecular Proton Transfer of Glycine in Aqueous Solution Using Quantum Mechanics−Molecular Mechanics Simulations

Author

Tunon, I., Silla, E., Millot, C., Martins-Costa, M. T. C., and Ruiz-Lopez, M. F.

Abstract

Molecular dynamics simulations within the density functional−molecular mechanics approach are used to investigate amino acid chemistry in aqueous solution. Equilibrium solvation effects are studied in both the neutral and zwitterionic forms of the glycine. Dynamic solvent effects on amino acid reactions in water are illustrated through the simulation of the fast conversion of neutral glycine to its zwitterionic form. The different factors contributing to the intramolecular proton transfer are analyzed from a dynamic point of view.

Published
1998

46. Ab Initio Calculations on Neutral and Alkaline Hydrolyses of β-Lactam Antibiotics. A Theoretical Study Including Solvent Effects

Author

Pitarch, J., Ruiz-Lopez, M. F., Pascual-Ahuir, J.-L., Silla, E., and Tunon, I.

Abstract

In this work we present a theoretical study of neutral and alkaline hydrolyses of N-methylazetidinone as a model of biological hydrolysis of β-lactam antibiotics. Calculations have been carried out at the HF and MP2 levels using the 3-21G, 6-31G*, and 6-31+G* basis sets. Solvent effects have been included by means of a polarizable continuum model. Our results indicate two possible reaction mechanisms for the β-lactam hydrolysis:  concerted and stepwise. In both the neutral and alkaline hydrolyses the concerted mechanism presents a free energy barrier lower than that of the stepwise mechanism.

Published
1997

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