New results on metric-locating-dominating sets of graphs

A dominating set S of a graph is a metric-locating-dominating set if each vertex of the graph is uniquely distinguished by its distanc es from the elements of S , and the minimum cardinality of such a set is called the metri c-location- domination number. In this paper, we undertake a study that, in general graphs and specific families, relates metric-locating-dominatin g sets to other special sets: resolving sets, dominating sets, locating-dominating set s and doubly resolving sets. We first characterize classes of trees according to cer tain relationships between their metric-location-domination number and thei r metric dimension and domination number. Then, we show different methods to tran sform metric- locating-dominating sets into locating-dominating sets a nd doubly resolving sets. Our methods produce new bounds on the minimum cardinalities of all those sets, some of them involving parameters that have not been related so farPostprint (published version

Determinantes del tipo impositivo efectivo en el sector turístico: un modelo dinámico con datos de panel

This paper presents a dynamic model of the Effective Tax Rate (ETR) in the tourism sector. A dynamic model where the lagged endogenous variable ETR has been included as a regressor to identify the dynamic structure of the variable due to the existence of temporal adjustments between the short and long run in ETR payments has been estimated. The empirical analysis based on a panel data set over the 2008-2013 period explores the determinants of the ETR variable by using a Generalised Method of Moments (GMM) estimator controlling for heterogeneity in the tourism sector. The Arellano-Bond system GMM estimator has been used to estimate the model. The study seeks to shed light on the determinants of tax burden in the tourism sector covering the lack of studies on this topic. The findings obtained suggest that the ETR borne is determined by size, financing structure and type of entity. We deem the finding of the existence of non-linear relationships between ETR and size and financing structure relevant.Este artículo presenta un modelo dinámico para el Tipo Impositivo Efectivo (TIE) en el sector turístico. Este modelo dinámico ha sido estimado usando la variable endógena retardada TIE como regresor para identificar la estructura dinámica de dicha variable, debido a la existencia de ajustes entre el corto y largo plazo en los pagos del TIE. El análisis empírico basado en datos de panel en el periodo 2008-2013 explora los determinantes de la variable TIE utilizándose el estimador del Método Generalizado de Momentos (GMM) controlando la heterogeneidad en el sector turístico. El estimador de Arellano-Bond ha sido utilizado para estimar el modelo. Este estudio busca arrojar luz sobre los determinantes de las cargas impositivas en el sector turístico debido a la escasez de estudios en esta materia. Los resultados obtenidos sugieren que el TIE se encuentra determinado por el tamaño, la estructura financiera y el tipo de empresa. Igualmente consideramos relevante el hallazgo de relaciones no lineales entre el TIE y el tamaño y la estructura de financiación

Metal Accumulation by Jatropha curcas L. Adult Plants Grown on Heavy Metal-Contaminated Soil

Jatropha curcas has the ability to phytoextract high amounts of heavy metals during its first months just after seeding. Notwithstanding, there is scarce information about metal uptake by adult J. curcas plants. To shed light on this issue, 4-year-old J. curcas L. plants were planted in a soil mixture of peat moss and mining soil (high metals content), and the biomass growth and metal absorption during 90 days were compared with those of plants growing in peat moss. The main metal found in the mining soil was Fe (31985 mg kg-1) along with high amounts of As (23717 mg kg-1). After the 90-day phytoremediation, the plant removed 29% of Fe and 44% of As from the soil mixture. Results revealed that J. curcas L. translocated high amounts of metals to its aerial parts, so that translocation factors were much higher than 1. Because of the high translocation and bioaccumulation factors obtained, J. curcas L. can be regarded as a hyperaccumulator plant. Despite the great capacity of J. curcas L. to phytoremediate heavy-metal-contaminated soils, the main drawback is the subsequent handling of the metal-contaminated biomass, although some potential applications have been recently highlighted for this biomass.University of Seville (VIPPIT-2019-I.5

El riesgo en el contrato de obra

Este artículo pretende dar respuesta al interrogante planteado a partir de una metodología empírica y práctica, de análisis de la legislación, la jurisprudencia y la doctrina, para arribar a unas conclusiones útiles para entidades públicas y contratistas del Estado

Elaboration and characterization of nanoemulsion with orange essential oil and pectin

BACKGROUND: Nanoemulsions formulated with citric essential oils are currently of interest because of their physical and chemical properties and multiple applications in areas such as the food industry or agrochemicals. These are thermodynamically unstable and have almost Newtonian flow behaviour, but a suitable formulation allows systems to be obtained with good physical stability and rheological properties. The addition of pectin makes this possible. In this work, food nanoemulsions formulated with pectin, orange essential oil (5 wt%), and Tween 80 were obtained by microfluidization. First, the effect of Tween 80 concentration from 1 to 5 wt% on emulsions without pectin was evaluated. Then, pectin was added to the most stable nanoemulsion obtained and two variables were studied: the pectin solution concentration (from 2 to 6 wt%) and the pectin/emulsion ratio (1:1 or 2:1) at a fixed pectin concentration. RESULTS: Rheological, laser diffraction, and multiple light scattering techniques were employed to determine the content of Tween 80 that results in the most stable nanoemulsion without pectin, which was 3 wt%. In addition, these techniques were used to determine the structure and physical stability of the nanoemulsions containing orange essential oil and pectin. The results obtained showed that the emulsions containing 2 wt% pectin were destabilized before 24 h. Furthermore, the emulsion with 6 wt% pectin and a 2:1 pectin/emulsion ratio showed the highest viscosity and the lowest mean diameters, and therefore the greatest stability. CONCLUSION: This work extends the knowledge of formulation of nanoemulsions and using essential oils. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.Ministerio de Economía y Competitividad CTQ2015-70700-

Dominating 2-broadcast in graphs: complexity, bounds and extremal graphs

Limited dominating broadcasts were proposed as a variant of dominating broadcasts, where the broadcast function is upper bounded. As a natural extension of domination, we consider dominating 2-broadcasts along with the associated parameter, the dominating 2-broadcast number. We prove that computing the dominating 2-broadcast number is a NP-complete problem, but can be achieved in linear time for trees. We also give an upper bound for this parameter, that is tight for graphs as large as desired.Peer ReviewedPostprint (author's final draft

Influencia del tensioactiu en la formació i estabilitat física d’emulsions ecològiques concentrades

El objetivo de esta investigación fue comparar tres tensoactivos ecológicos derivados del aceite de coco para la preparación de emulsiones aceite-en-agua concentradas formuladas con α-pineno. Los tensoactivos utilizados son ésteres polietoxilados de glicerina que presentan diferente número de grupos de óxido de etileno, que son responsables principales del carácter hidrófilo del tensoactivo. Las técnicas utilizadas para caracterizar las emulsiones fueron la reología, la difracción láser y el “multiple light scattering”. Se ha demostrado que el uso del tensoactivo no-iónico Levenol C-201 (17 grupos de óxido de etileno y valor HLB de 13), produce emulsiones con mayor estabilidad física debido a sus menores tamaños de gota y una mayor viscosidad, lo que ayuda a prevenir fenómenos de desestabilización como el cremado o la coalescencia. Por tanto, este estudio proporciona importantes resultados sobre las propiedades y estabilidad física de emulsiones formuladas con ésteres etoxilados de glicerina derivados del aceite de coco que pueden ser utilizadas para el desarrollo de nuevos productos bioaplicables.The goal of this work was to compare three different ecological surfactants derived from coconut oil for the preparation of concentrated oil-in-water emulsions formulated with alpha-pinene. The surfactants used were polyoxyethylene glycerol fatty acid esters with different number of oxyethylene groups. These are liable for the hydrophilic surfactant role. Rheology, laser diffraction and Multiple Ligh Sacttering were used in order to characterise the emulsions. It has been demonstrated that the use of Levenol C-201 (HLB: 13) lead to prepare emulsions with longer physical stability due to lower droplet size and higher viscosity. These facts help to slow down destabilization processes such as creaming or coalescence. Therefore, this study provides interesting results about the properties and physical stability of emulsions containing polyoxyethylene glycerol fatty acid esters derived from coconut oil, which can be used to develop new products with biological applications.L’objectiu d’aquesta investigació va ser comparar tres tensioactius ecològics derivats de l’oli de coco per a la preparació d’emulsions oli-en-aigua concentrades formulades amb α-pinè. Els tensioactius utilitzats són èsters polietoxilats de glicerina que presenten diferent nombre de grups d’òxid d’etilè, que són responsables principals del caràcter hidròfil del tensioactiu. Les tècniques utilitzades per caracteritzar les emulsions van ser la reologia, la difracció làser i el multiple light scattering. S’ha demostrat que l’ús del tensioactiu no-iònic Levenol C-201 (17 grups d’òxid d’etilè i valor HLB de 13), produeix emulsions amb més estabilitat física a causa de un volum més petit de gota i una major viscositat, el que ajuda a prevenir fenòmens de desestabilització com el cremat o la coalescència. Per tant, aquest estudi proporciona importants resultats sobre les propietats i la estabilitat física d’emulsions formulades amb èsters etoxilats de glicerina derivats de l’oli de coco que poden ser utilitzades per al desenvolupament de nous productes bioaplicables.(Project CTQ2015- 70700) from the Spanish Ministerio de Economía y CompetitividadEuropean Commission (FEDER Programme)KA

Influence of nanoemulsion/gum ratio on droplet size distribution, rheology and physical stability of nanoemulgels containing inulin and omega-3 fatty acids

Background: New consumer habits are forcing the food industry to develop new and healthy products. In response to this tendency, in this investigation, we obtained nanoemulgels by microfluidization containing inulin fibre and omega-3 fatty acids. First, the influence of the number of microfluidization cycles on the physical properties of the nanoemulsions was studied. Subsequently, an advanced-performance xanthan gum was added to the nanoemulsion in different nanoemulsion/xanthan ratios (1:1, 2:1, 3:1, 4:1, 1:2, and 1:3). Results: Laser diffraction, multiple light scattering, and rheology techniques were used to characterize nanoemulsions and the corresponding nanoemulgels. The nanoemulsion with the lowest Sauter mean diameter (138 nm) and the longest physical stability was obtained after three passes through a microfluidization device at a fixed pressure of 103 421 kPa. Thus, these processing conditions were always used to obtain the nanoemulsion; these were subsequently mixed with a xanthan gum solution to produce nanoemulgels that showed weak gel-like viscoelastic and shear-thinning flow behaviours. A decrease in the nanoemulsion/xanthan ratio (i.e. by an increase in the content of xanthan gum in the nanoemulgel) increased the viscoelastic moduli and the zero shear viscosity values. A rise in the droplet size was observed with aging time, probably due to flocculation. The nanoemulsion/xanthan gum mass ratio of 1:3 yielded the most stable nanoemulgel. Conclusions: This work is a contribution to the development of functional foods. It has been demonstrated that it is possible to obtain a stable nanoemulgel-based food matrix containing fibre and omega-3 fatty acids. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.Universidad de Sevilla PP2019-1329

Metric-locating-dominating sets of graphs for constructing related subsets of vertices

© 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/A dominating set S of a graph is a metric-locating-dominating set if each vertex of the graph is uniquely distinguished by its distances from the elements of S , and the minimum cardinality of such a set is called the metric-location-domination number. In this paper, we undertake a study that, in general graphs and specific families, relates metric-locating-dominating sets to other special sets: resolving sets, dominating sets, locating-dominating sets and doubly resolving sets. We first characterize the extremal trees of the bounds that naturally involve metric-location-domination number, metric dimension and domination number. Then, we prove that there is no polynomial upper bound on the location-domination number in terms of the metric-location-domination number, thus extending a result of Henning and Oellermann. Finally, we show different methods to transform metric-locating-dominating sets into locating-dominating sets and doubly resolving sets. Our methods produce new bounds on the minimum cardinalities of all those sets, some of them concerning parameters that have not been related so farPeer ReviewedPostprint (author's final draft