Methodology to calibrate the dissection properties of aorta layers from two sets of experimental measurements

Aortic dissection is a prevalent cardiovascular pathology that can have a fatal outcome. However, the mechanisms that trigger this disease and the mechanics of its progression are not fully understood. Computational models can help understand these issues, but they need a proper characterisation of the tissues. Therefore, we propose a methodology to obtain the dissection parameters of all layers in aortic tissue via the computational modelling of two different delamination tests: the peel and mixed tests. Both experimental tests have been performed in specimens of porcine aorta, where the intima-media and media-adventitia interfaces, as well as the medial layer, were dissected. These two tests have been modelled using a cohesive zone formulation for the separating interface and a hyperelastic anisotropic material model via an implicit static analysis. The dissection properties of each interface have been calibrated by reproducing the force-displacement curves obtained in the experimental tests. The values of peak and mean force of the experiments were fitted with an error below 10%. With this methodology, we intend to contribute to the development of reliable numerical tools for simulating aortic dissection and aortic aneurysm rupture. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

N,N′-Bis(4-amino­benz­yl)oxalamide

In the title compound, C16H18N4O2, the two carbonyl groups are in an anti­periplanar conformation with an O=C—C=O torsion angle of 173.86 (17)°. In the crystal, a pair of inter­molecular N—H⋯O hydrogen bonds, forming an R 2 2(10) ring motif, connect the mol­ecules into an inversion dimer. The dimers are further linked by N—H⋯N and C—H⋯π inter­actions, forming a zigzag chain along the b axis

The design and characterisation of sol–gel coatings for the controlled-release of active molecules

The controlled release of active agents from a matrix has become increasingly important for oral, transdermal or implantable therapeutic systems, due to the advantages of safety, efficacy and patient convenience. Controlled-release hybrid (organic-inorganic) sol-gel coating synthesis has been performed to create a sol with an active molecule included (procaine). Synthesis procedures included acid-catalysed hydrolysis, sol preparation, the addition of a procaine solution to the sol, and the subsequent gelation and drying. The alkoxide precursors used were triethoxyvinylsilane and tetraethyl-orthosilicate (TEOS) in molar ratios of 1:0, 9:1, 8:2 and 7:3. After the determination of the optimal synthesis parameters, the material was physicochemically characterised by silicon-29 nuclear magnetic resonance (²⁹Si-NMR) and Fourier transform infrared spectroscopy, contact angle analysis and electrochemical impedance spectroscopy tests. Finally, the materials were assayed in vitro for their ability to degrade by hydrolysis and to release procaine in a controlled manner. The sustained release of procaine over a 3-day period was demonstrated. A close correlation between release and degradation rates suggests that film degradation is the main mechanism underlying the control of release. Electrochemical analysis reveals the formation of pores and water uptake during the degradation. The quantity of TEOS is one of the principal parameters used to determine the kinetics of degradation and procaine release.The supports of the Spanish Ministry of Economy and Competitiveness through project IPT-010000-2010-004 and of the University of the Basque Country (UPV/EHU) through ‘‘UFI11/56’’ are kindly acknowledge

Study of the effects of ionic liquid-modified cathodes and ceramic separators on MFC performance

© 2016 Elsevier B.V. Ceramic-based MFC designs have proven to be a low cost alternative for power production and wastewater treatment. The use of ionic liquids in ceramic MFCs is explored for the first time in the present work in order to improve power output. The ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][Tf2N], has been selected for this purpose due to its advantageous properties. The performance of activated carbon cathodes using polytetrafluoroethylene (PTFE) binder and different carbon diffusion layers (DL) (controls) is compared with two types of ionic liquid-modified cathodes (test). This work continues to study the performance of terracotta separators modified with the same ionic liquid, neat and also mixed with PTFE. Whilst the results show operational limitations when the IL is integrated in the ceramic separator, there is a significant enhancement of the MFC performance when added as part of the activated layer mixture of the cathode, achieving up to 86.5% more power output in comparison with IL-free MFCs (from 229.78 μW to 428.65 μW). The addition of a layer of PTFE-mixed ionic liquid spread on the activated layer of the cathode also leads to an increase in power of approximately 37%

Ultracold O2O_2+O2O_2 collisions in a magnetic field: on the role of the potential energy surface

The collision dynamics of $^{17}O_2(^3\Sigma_g^-) +^{17}O_2(^3\Sigma_g^-)$ in the presence of a magnetic field is studied within the close-coupling formalism in the range between 10 nK and 50 mK. A recent global {\em ab initio} potential energy surface (PES) is employed and its effect on the dynamics is analyzed and compared with previous calculations where an experimentally derived PES was used [New J. Phys {\bf 11}, 055021 (2009)]. In contrast to the results using the older PES, magnetic field dependence of the low-field-seeking state in the ultracold regime is characterized by quite a large background scattering length, $a_{bg}$, and, in addition, cross sections exhibit broad and pronounced Feshbach resonances. The marked resonance structure is somewhat surprising considering the influence of inelastic scattering, but it can be explained by resorting to the analytical van der Waals theory, where the short range amplitude of the entrance channel wave function is enhanced by the large $a_{bg}$. This strong sensitivity to the short range of the {\em ab initio} PES persists up to relatively high energies (10 mK). After this study and despite quantitative predictions are very difficult, it can be concluded that the ratio between elastic and spin relaxation scattering is generally small, except for magnetic fields which are either low or close to an asymmetric Fano-type resonance. Some general trends found here, such as a large density of quasibound states and a propensity towards large scattering lengths, could be also characteristic of other anisotropic molecule-molecule systems.Comment: 24 pages, 8 figure

Examination of the Feynman-Hibbs Approach in the Study of NeN_N-Coronene Clusters at Low Temperatures

Feynman-Hibbs (FH) effective potentials constitute an appealing approach for investigations of many-body systems at thermal equilibrium since they allow us to easily include quantum corrections within standard classical simulations. In this work we apply the FH formulation to the study of Ne$_N$-coronene clusters ($N=$ 1-4, 14) in the 2-14 K temperature range. Quadratic (FH2) and quartic (FH4) contributions to the effective potentials are built upon Ne-Ne and Ne-coronene analytical potentials. In particular, a new corrected expression for the FH4 effective potential is reported. FH2 and FH4 cluster energies and structures -obtained from energy optimization through a basin-hoping algorithm as well as classical Monte Carlo simulations- are reported and compared with reference path integral Monte Carlo calculations. For temperatures $T> 4$ K, both FH2 and FH4 potentials are able to correct the purely classical calculations in a consistent way. However, the FH approach fails at lower temperatures, especially the quartic correction. It is thus crucial to assess the range of applicability of this formulation and, in particular, to apply the FH4 potentials with great caution. A simple model of $N$ isotropic harmonic oscillators allows us to propose a means of estimating the cut-off temperature for the validity of the method, which is found to increase with the number of atoms adsorbed on the coronene molecule

Nuevos datos geocronológicos 40Ar-39Ar en dos puntos singulares del macizo de Anaga (Tenerife): Punta Poyata e Igueste de San Andrés. Consecuencias de interés

En este trabajo se aportan nuevos datos geocronológicos Ar40-Ar39 en rocas ancaramíticas submarinas localizadas en dos puntos singulares del macizo de Anaga (NE de Tenerife): las ancaramitas submarinas hidrotermalizadas de Punta Poyata (NNW de Anaga) y las lavas submarinas ancaramíticas del Barranco de Igueste (SE de Anaga). Las muestras estudiadas pertenecen a afloramientos pertenecientes a los niveles estratigráficos más inferiores de la secuencia volcánica que conforma el edificio de Anaga. En Punta Poyata se tomaron dos especímenes que dieron edades de 12,2 ± 1,9 Ma and 13,0 ± 1,0 Ma. En el barranco de Igueste los resultados geocronológicos de las muestras tomadas dieron edades de 12,7 ± 1,6 Ma and 9,7 ± 1,0 Ma. Estos datos sugieren que el macizo de Anaga comenzó su desarrollo subaéreo antes de lo que anteriormente se creía, ajustándose dicho período inicial al Mioceno Medio en lugar de al Mioceno tardío como previamente se asumía.This work provides new Ar40-Ar39 geochronological data in submarine ankaramite rocks located in two distant points of Anaga (NE Tenerife): the submarine hydrothermally altered ankaramites of Punta Poyata area (NNW Anaga) and the ankaramitic pillow lavas at Barranco de Igueste (SE Anaga). The studied samples were collected from outcrops of the lowest stratigraphic levels throughout the volcanics that build up the Anaga massif. At Punta Poyata, two collected samples yielded an age of 12,2 ± 1,9 Ma and 13,0 ± 1,0 Ma. At Barranco de Igueste, sample results are of 12,7 ± 1,6 Ma and 9,7 ± 1,0 Ma. These data support the assumption that the Anaga massif began its subaerial growth earlier than that previously was supposed, most likely in the Mid-Miocene Instead of late Miocene as currently believed.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu