Self-similar transmission properties of aperiodic Cantor potentials in gapped graphene

We investigate the transmission properties of quasiperiodic or aperiodic structures based on graphene arranged according to the Cantor sequence. In particular, we have found self-similar behaviour in the transmission spectra, and most importantly, we have calculated the scalability of the spectra. To do this, we implement and propose scaling rules for each one of the fundamental parameters: generation number, height of the barriers and length of the system. With this in mind we have been able to reproduce the reference transmission spectrum, applying the appropriate scaling rule, by means of the scaled transmission spectrum. These scaling rules are valid for both normal and oblique incidence, and as far as we can see the basic ingredients to obtain self-similar characteristics are: relativistic Dirac electrons, a self-similar structure and the non-conservation of the pseudo-spin. This constitutes a reduction of the number of conditions needed to observe self-similarity in graphene-based structures, see D\'iaz-Guerrero et al. [D. S. D\'iaz-Guerrero, L. M. Gaggero-Sager, I. Rodr\'iguez-Vargas, and G. G. Naumis, arXiv:1503.03412v1, 2015]

Antioxidant activity of alkyl gallates and glycosyl alkyl gallates in fish oil in water emulsions: Relevance of their surface active properties and of the type of emulsifier

The antioxidant activity of gallic acid and a series of alkyl gallates (C4-C18) and glycosylated alkyl gallates (C4-C18) on fish oil-in-water emulsions was studied. Three types of emulsifiers, lecithin, Tween-20 and sodium dodecyl sulphate (SDS) were tested. A nonlinear behavior of the antioxidant activity of alkyl gallates when increasing alkyl chain length was observed for emulsions prepared with lecithin. Medium-size alkyl gallates (C6-C12) were the best antioxidants. In contrast, for emulsions prepared with Tween-20, the antioxidants seem to follow the polar paradox. Glucosyl alkyl gallates were shown previously to be better surfactants than alkyl gallates. Nevertheless, they exhibited a worse antioxidant capacity than their corresponding alkyl gallates, in emulsions prepared with lecithin or Tween-20, indicating the greater relevance of having three OH groups at the polar head in comparison with having improved surfactant properties but just a di-ortho phenolic structure in the antioxidant

Evaluation of \u3ci\u3eCentrosema rotundifolium\u3c/i\u3e for Sand-Soil Savannas in Eastern Venezuela

An evaluation of a collection of amphicarpic Centrosema rotundifolium showed considerable variability among the six accessions tested, regarding above- and below-ground seed production. Dry-season forage yields were very low but rainy-season yields reached acceptable levels. Contents of crude protein, P and Ca were intermediate to high (CP and P) or low (Ca). Three accessions are suggested for on-farm testing in association with grasses in order to explore the plant persistence implications of belowground seed production under practical conditions. Furthermore, the potential of this amphicarpic species for the conservation of sandy soils deserves attention

CFD simulation of a hyperloop capsule inside a closed environment

[EN] One of the most restrictive conditions in ground transportation is traveling through a tunnel at high speed. In those conditions waves are propagated, increasing the pressure upstream the object, and so, the drag compared to the open flow case. Although this drawback is mitigated with larger tunnels, another proposed solution is to decrease the pressure inside the tunnel. In this paper it is demonstrated that the drag coefficient is almost invariant with the pressure conditions. This effect allows, not only to have smaller tunnels with respect to the existing for standard trains, but also to enhance the speed of the train without increasing its aerodynamic losses.SH and FLR work have been supported by project RTI2018-102256-B-I00 of Mineco/FEDER. FLR is partially funded buy MCIU under grant DI-17-09616.Lluesma-Rodríguez, F.; González, T.; Hoyas, S. (2021). CFD simulation of a hyperloop capsule inside a closed environment. Results in Engineering. 9:1-3. https://doi.org/10.1016/j.rineng.2020.10019613

Crack-Depth Prediction in Steel Based on Cooling Rate

One criterion for the evaluation of surface cracks in steel welds is to analyze the depth of the crack, because it is an effective indicator of its potential risk. This paper proposes a new methodology to obtain an accurate crack-depth prediction model based on the combination of infrared thermography and the 3D reconstruction procedure. In order to do this, a study of the cooling rate of the steel is implemented through active infrared thermography, allowing the study of the differential thermal behavior of the steel in the fissured zone with respect to the nonfissured zone. These cooling rate data are correlated with the real geometry of the crack, which is obtained with the 3D reconstruction of the welds through a macrophotogrammetric procedure. In this way, it is possible to analyze the correlation between cooling rate and depth through the different zones of the crack. The results of the study allow the establishment of an accurate predictive depth model which enables the study of the depth of the crack using only the cooling rate data. In this way, the remote measure of the depth of the surface steel crack based on thermography is possible

An iterated Radau method for time-dependent PDE's

This paper is concerned with the time integration of semi-discretized, multi-dimensional PDEs of advection-diffusion-reaction type. To cope with the stiffness of these ODEs, an implicit method has been selected, viz., the two-stage, third-order Radau IIA method. The main topic of this paper is the efficient solution of the resulting implicit relations. First a modified Newton process has been transformed into an iteration process in which the 2 stages are decoupled and, moreover, can exploit the same LU-factorization of the iteration matrix. Next, we apply a so-called Approximate Matrix Factorization (AMF) technique to solve the linear systems in each Newton iteration. This AMF approach is very efficient since it reduces the `multi-dimensional' system to a series of `one-dimensional' systems. The total amount of linear algebra work involved is reduced enormously by this approach. The idea of applying AMF to two-dimensional problems is quite old and goes back to Peaceman and Rachford in the early fifties. The situation in three space dimensions is less favourable and will be analyzed here in more detail, both theoretically and experimentally. Furthermore, we analyze a variant in which the AMF-technique has been used to really solve (`until convergence') the underlying Radau IIA method so that we can rely on its excellent stability and accuracy characteristics. Finally, the method has been tested on several examples. Also a comparison has been made with the existing codes VODPK and IMEXRKC, and the efficiency (CPU time versus accuracy) is shown to be at least competitive with the efficiency of these solvers

The Kinematics of HH 34 from HST Images with a Nine-year Time Baseline

We study archival HST [S II] 6716+30 and Hα images of the HH 34 outflow, taken in 1998.71 and in 2007.83. The ~9 yr time baseline and the high angular resolution of these observations allow us to carry out a detailed proper-motion study. We determine the proper motions of the substructure of the HH 34S bow shock (from the [S II] and Hα frames) and of the aligned knots within ~30'' from the outflow source (only from the [S II] frames). We find that the present-day motions of the knots along the HH 34 jet are approximately ballistic, and that these motions directly imply the formation of a major mass concentration in ~900 yr, at a position similar to the one of the present-day HH 34S bow shock. In other words, we find that the knots along the HH 34 jet will merge to form a more massive structure, possibly resembling HH 34S

Chiral transition-metal complexes as Brønsted-acid catalysts for the asymmetric Friedel-Crafts hydroxyalkylation of indoles.

The Friedel-Crafts reaction between 3,3,3-trifluoropyruvates and indoles is efficiently catalysed by the iridium complex [(η5-C 5Me5)Ir{(R)-Prophos}(H2O)][SbF 6]2 (1) with up to 84% ee. Experimental data and theoretical calculations support a mechanism involving the Brønsted-acid activation of the pyruvate carbonyl by the protons of the coordinated water molecule in 1. Water is not dissociated during the process and, therefore, the catalytic reaction occurs with no direct interaction between the substrates and the metal. This journal is © the Partner Organisations 2014.The authors acknowledge the Ministerio de Economía y Competitividad (MINECO, Grants CTQ2006-03030/BQU, CTQ2009-10303/BQU, CTQ2011-27033 and Consolider Ingenio 2010 CSD2006-003), Gobierno de Aragón (Grupo Consolidado: Catálisis Homogénea Enantioselectiva), Generalitat de Catalunya (2009SGR0259) and the ICIQ foundation for financial support. A. S. and R. R. acknowledge MINECO for predoctoral fellowships. S. D.-G. acknowledges MINECO for a “Torres Quevedo” contract.Peer Reviewe

Egg development and toxicity of insecticides to eggs, neonate larvae and adults of Xylotrechus arvicola, a pest in Iberian grapevines

Xylotrechus arvicola (Coleoptera: Cerambycidae) is a xylophagous species that is becoming an important pest in vineyards in the Iberian Peninsula. The most sensitive stages are adult and egg, but their neonate larvae can also be attacked during the first 24 h after hatching and before entering the wood. Adults were evaluated for seven days against the insecticides spinosad, Beauveria bassiana, imidacloprid and chlorpyrifos and neonate larvae (< 24 h) and eggs of different ages against the described insecticides, as well as flufenoxuron and pyriproxyfen. All insecticides were applied in a Potter tower at a maximum and minimum commercial dose, and showed significant differences both among insecticides as between the applied doses. Most of the hatching occurs eight days after oviposition by X. arvicola females. Chlorpyrifos had a quick and total control of eggs of different ages, neonate larvae and adults in both dosis applied, but its effectiveness could cause serious effects on other non-target species. Pyriproxifen and flufenoxuron had the best ovicidal control when the age of eggs increases and, B. bassiana also had a good ovicidal control, due its capacity to invade the eggs actively through their shell and proliferate inside them. Biological insecticides such as B. bassiana and spinosad, with a total control on adults and good rates of mortality of neonate larvae and eggs can be a great instrument to biological control of this pest

Empleo de la composición química de minerales ferromagnesianos como indicadores de variables termodinámicas y químicas en la cristalización de rocas igneas: aplicación a los casos particulares de biotitas y granitoides del centro oeste de España

Se establecen en biotitas las relaciones entre: Rb y K/Rb y la naturaleza del granito, funciones de los contenidos en Al, Fe y Mg y la alcalinidad y temperatura en la cristalización, y finalmente, paragénesis de minerales alumínicos, grado de influencia en los diversos elementos en las esferasde coordinación tetraédrica y octaédrica, y variaciones de contenidos en elementos trazas con la alcalinidad. Las conclusiones se vinculan a la génesis de yacimientos típicamente asociados a granitos