Kinetic study of the gas-phase reaction of atomic chlorine with a series of aldehydes

The reactions of Cl atoms with a series of unsaturated aldehydes have been investigated for the first time using a relative method. In order to obtain additional information for a qualitative structure versus reactivity discussion, we have also determined the rate coefficients for the reactions of atomic chlorine with their respective saturated aldehydes. These relative measurements were performed at room temperature and atmospheric pressure of air and N₂, by using ethane, propene and 1-butene as reference compounds. The weighted average relative rate constants obtained, k_Cl&plusmn;2&sigma; (in units of cm³ molecule^&minus;1 s^&minus;1) were: trans-2-pentenal (1.31&plusmn;0.19)&times;10^&minus;10; trans-2-hexenal (1.92&plusmn;0.22)&times;10^&minus;10; trans-2-heptenal (2.40&plusmn;0.29)&times;10^&minus;10; n-pentanal (2.56&plusmn;0.27)&times;10^&minus;10; n-hexanal (2.88&plusmn;0.37)&times;10^&minus;10; n-heptanal (3.00&plusmn;0.34)&times;10^&minus;10. <P style='line-height: 20px;'> Finally, results and atmospheric implications are discussed and compared with the reactivity with OH and NO₃ radicals

Constitutive sensitivity of the oscillatory behaviour of hyperelastic cylindrical shells

Free and forced nonlinear radial oscillations of a thick-walled cylindrical shell are investigated. The shell material is taken to be incompressible and isotropic within the framework of finite nonlinear elasticity. In comparison with previous seminal works dealing with the dynamic behaviour of hyperelastic cylindrical tubes, in this paper we have developed a broader analysis on the constitutive sensitivity of the oscillatory response of the shell. In this regard, our investigation is inspired by the recent works of Bucchi and Hearn (2013) [28,291, who carried out a constitutive sensitivity analysis of similar problem with hyperelastic cylindrical membranes subjected to static inflation. In the present paper we consider two different Helmholtz free-energy functions to describe the material behaviour: Mooney-Rivlin and Yeoh constitutive models. We carry out a systematic comparison of the results obtained by application of both constitutive models, paying specific attention to the critical initial and loading conditions which preclude the oscillatory response of the cylindrical tube. It has been found that these critical conditions are strongly dependent on the specific constitutive model selected, even though both Helmholtz free-energy functions were calibrated using the same experimental data.The authors are indebted to the Ministerio de Economía y Competitividad de España (Project DPI2014–57989–P) for the financial support which permitted to conduct this work

Corrigendum to "Constitutive sensitivity of the oscillatory behaviour of hyperelastic cylindrical shells" [J. Sound Vib. 358 (2015) 199–216].

An error has been found in Eq. (25) of the recently published paper (https://doi.org/10.1016/j.jsv.2015.07.031) and the authors wish to correct the record by means of this corrigendum. In summary, the error in Eq. (25) of yielded results in which the shell modelled with the Yeoh material showed a non-oscillatory response for some specific loading conditions. This is not the case, as demonstrated in this brief note. We would like to apologize to the readers of the Journal of Sound and Vibration for any inconvenience this error may have caused

Nonlinear resonances of an idealized saccular aneurysm

This paper investigates the occurrence of dynamic instabilities in idealized intracranial saccular aneurysms subjected to pulsatile blood flow and surrounded by cerebral spinal fluid. The problem has been approached extending the original 2D model of Shah and Humphrey (1999) to a 3D framework. The justification for using a 3D formulation arises from the works of Suzuki and Ohara (1978), MacDonald et al. (2000) and Costalat et al. (2011) who showed experimental evidences of intracranial aneurysms with a ratio between wall thickness and inner radius larger that 0.1. Two different material models have been used to describe the mechanical behaviour of the aneurysmal wall: Neo-Hookean and Mooney-Rivlin. To the authors' knowledge, for the first time in literature, the dynamic response of the aneurysm has been analysed using complete nonlinear resonance diagrams that have been obtained from a numerical procedure specifically designed for that purpose. Our numerical results show that, for a wide range of wall thicknesses and both constitutive models considered, the saccular aneurysms are dynamically stable within the range of frequencies associated to the normal heart rates, which confirms previous results of Shah and Humphrey (1999). On the other hand, our results also show that the geometric and material nonlinearities of the problem could bring closer than expected the resonance frequencies of the aneurysm to the frequencies of the pulsatile blood flow.The authors are indebted to the Spanish Ministry of Economy and Competitiveness (Project EUIN2015-62556) for the financial support received which allowed conducting part of this work

Modeling deformation and failure of elastomers at high strain rates

In this paper we develop a new constitutive model to describe the viscoelastic response of elastomers subjected to high strain rates. The key and original feature of the model is that it takes into account the failure of the material using an energy limiter. We calibrate the constitutive model for various strain rates using the experimental data reported by Hoo Fatt and Ouyang (2008) and show the capacity of the proposed formulation to describe the rate-dependent behavior of styrene butadiene rubber. In addition, we implement the model into ABAQUS/Explicit using a simple scheme for the temporal integration of the constitutive equations. Finally, we show sample numerical simulations to illustrate the joint performance of the constitutive model and the integration algorithm.DAI, GV and JARM are indebted to the Spanish Ministry of Economy and Competitiveness (Projects EUIN2015-62556 and DPI2014-57989-P) for the financial support received which allowed conducting part of this work. KYV acknowledges support from the Israel Science Foundation, grant No. ISF-198/15.Publicad

Fabrication and deposition of copper and copper oxide nanoparticles by laser ablation in open air

The proximity of the “post-antibiotic era”, where infections and minor injuries could be a cause of death, there are urges to seek an alternative for the cure of infectious diseases. Copper nanoparticles and their huge potential as a bactericidal agent could be a solution. In this work, Cu and Cu oxide nanoparticles were synthesized by laser ablation in open air and in argon atmosphere using 532 and 1064 nm radiation generated by nanosecond and picosecond Nd:YVO4 lasers, respectively, to be directly deposited onto Ti substrates. Size, morphology, composition and the crystalline structure of the produced nanoparticles have been studied by the means of field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), the energy dispersive spectroscopy of X-rays (EDS), selected area electron diffraction (SAED) and X-ray diffraction (XRD). The UV-VIS absorbance of the thin layer of nanoparticles was also measured, and the antibacterial capacity of the obtained deposits tested against Staphylococcus aureus. The obtained deposits consisted of porous coatings composed of copper and copper oxide nanoparticles interconnected to form chain-like aggregates. The use of the argon atmosphere contributed to reduce significantly the formation of Cu oxide species. The synthesized and deposited nanoparticles exhibited an inhibitory effect upon S. aureus.Peer ReviewedPostprint (published version

Urban Knowledge Extraction, Representation and Reasoning as a Bridge from Data City towards Smart City

Urban Data management represents a major challenge in the field of Smart Cities. Its understanding is essential for the development of better smart services, which are a persistent demand in urban policies. From all the sources of data available, those that involve a collective processing of urban information (by the citizens or other collectives) deliver in fact, useful insights into social perception. Such is the case, for example, of data collected from mobile networks. Prior to the design of sociotechnical artifacts in cities, it seems important to extract the qualitative and quantitative opinions, sentiment and feedbacks present in these data. In this paper we present three solutions for mining these contents through Knowledge Extraction methods, as a previous step to the prospection of new smart services.Ministerio de Economía y Competitividad TIN2013-41086-

Measuring the Difference Between Pictures From Controlled and Uncontrolled Sources to Promote a Destination. A Deep Learning Approach

Promoting a destination is a major task for Destination Marketing Organizations (DMOs). Although DMOs control, to some extent, the information presented to travelers (controlled sources), there are other different sources of information (uncontrolled sources) that could project an unfavorable image of the destination. Measuring differences between information sources would help design strategies to mitigate negative factors. In this way, we propose a deep learning-based approach to automatically measure the changes between images from controlled and uncontrolled information sources. Our approach exempts experts from the time-consuming task of assessing enormous quantities of pictures to track changes. To our best knowledge, this work is the first work that focuses on this issue using technological paradigms. Notwithstanding this, our approach paves novel pathways to acquire strategic insights that can be harnessed for the augmentation of destination development, the refinement of recommendation systems, the analysis of online travel reviews, and myriad other pertinent domains

A non-separability measure for spatially disjoint vectorial fields

Vectorial forms of structured light that are non-separable in their spatial and polarisation degrees of freedom have become topical of late, with an extensive toolkit for their creation and control. In contrast, the toolkit for quantifying their non-separability, the inhomogeneity of the polarisation structure, is less developed and in some cases fails altogether. To overcome this, here we introduce a new measure for vectorial light, which we demonstrate both theoretically and experimentally. We consider the general case where the local polarisation homogeneity can vary spatially across the field, from scalar to vector, a condition that can arise naturally if the composite scalar fields are path separable during propagation, leading to spatially disjoint vectorial light. We show how the new measure correctly accounts for the local path-like separability of the individual scalar beams, which can have varying degrees of disjointness, even though the global vectorial field remains intact. Our work attempts to address a pressing issue in the analysis of such complex light fields, and raises important questions on spatial coherence in the context of vectorially polarised light