On the resonances and polarizabilities of split ring resonators

In this paper, the behavior at resonance of split ring resonators SRRs and other related topologies, such as the nonbianisotropic SRR and the broadside-coupled SRR, are studied. It is shown that these structures exhibit a fundamental resonant mode the quasistatic resonance and other higher-order modes which are related to dynamic processes. The excitation of these modes by means of a properly polarized time varying magnetic and/or electric fields is discussed on the basis of resonator symmetries. To verify the electromagnetic properties of these resonators, simulations based on resonance excitation by nonuniform and uniform external fields have been performed. Inspection of the currents at resonances, inferred from particle symmetries and full-wave electromagnetic simulations, allows us to predict the first-order dipolar moments induced at the different resonators and to develop a classification of the resonances based on this concept. The experimental data, obtained in SRR-loaded waveguides, are in agreement with the theory and point out the rich phenomenology associated with these planar resonant structures.MEC (España)-TEC2004-04249-C02-01 y TEC2004-04249-C02-02Comunidad Europea (programa Eureka)-2895 TELEMACAgencia de Subvenciones de la República Checa-102/03/044

Generation of all-fiber ultrafast pulses at 2 µm by soliton self-frequency shift in highly nonlinear silica fiber

An efficient and straightforward method to obtain all-fiber pulsed sources at 2 μm is presented and experimentally demonstrated. It is based on the soliton self-frequency shift effect in a highly nonlinear fiber. The output power of a supercontinuum source is previously increased by an optimized homemade thulium-doped fiber amplifier. By coupling the amplified output power in a highly nonlinear fiber, the spectrum is shifted toward 130 nm and the spectral peak is located at 2014 nm. The power conversion factor reaches values as high as 0.93, without employing additional amplifiers. The mean spectral power of the 2 μm source reaches −4.6 dBm nm−1 (0.35 mW nm−1), its output power is 38 mW and the peak power of each pulse is higher than 27 kW

Effect of long range spatial correlations on the lifetime statistics of an emitter in a two-dimensional disordered lattice

The effect of spatial correlations on the Purcell effect in a bidimensional dispersion of resonant nanoparticles is analyzed. We perform extensive calculations on the fluorescence decay rate of a point emitter embedded in a system of nanoparticles statistically distributed according to a simple 2D lattice-gas model near the critical point. For short-range correlations (high temperature thermalization) the Purcell factors present a long-tailed statistic which evolves towards a bimodal distribution when approaching the critical point where the spatial correlation length diverges. Our results suggest long-range correlations as a possible origin of the large fluctuations of experimental decay rates in disordered metal films.Comment: 6 pages, 5 figure

Accurate circuit analysis of resonant-type left handed transmission lines with inter-resonator coupling

In this paper, a circuit model for the description of left handed transmission lines based on complementary split rings resonators CSRRs is proposed. As compared to previous models, coupling between adjacent resonators is included in the present work. The conditions that make this coupling significant are discussed. Specifically, it will be shown that it is barely present when circular CSRRs are used to implement the left handed transmission line. However, if the line is loaded with rectangular CSRRs separated by a small distance, inter-resonator coupling is important and it significantly influences the electromagnetic behavior of the structures. It will be also shown that under low or moderate coupling, it is possible to describe the structures by means of a simplified model with modified parameters. Several prototype devices with different CSRR topologies and coupling levels have been fabricated to illustrate the phenomenology associated with these structures and the accuracy of their model descriptions. The results of this work can be of interest for the design of planar microwave circuits based on CSRR left handed lines.Ministerio de Economía y Ciencias de España-TEC2004-04249-C02-01 y TEC2004-04249-C02-02Comisión Europea (Red de Excelencia)-E 500252-2 METAMORPHOS

Borates or phosphates? That is the question

[EN] Chemical nomenclature is perceived to be a closed topic. However, this work shows that the identification of polyanionic groups is still ambiguous and so is the nomenclature for some ternary compounds. Two examples, boron phosphate (BPO4) and boron arsenate (BAsO4), which were assigned to the large phosphate and arsenate families, respectively, nearly a century ago, are explored. The analyses show that these two compounds should be renamed phosphorus borate (PBO4) and arsenic borate (AsBO4). Beyond epistemology, this has pleasing consequences at several levels for the predictive character of chemistry. It paves the way for future work on the possible syntheses of SbBO4 and BiBO4, and it also renders previous structure field maps completely predictive, allowing us to foresee the structure and phase transitions of NbBO4 and TaBO4. Overall, this work demonstrates that quantum mechanics calculations can contribute to the improvement of current chemical nomenclature. Such revisitation is necessary to classify compounds and understand their properties, leading to the main final aim of a chemist: predicting new compounds, their structures and their transformations.This research was partially supported by Spanish MINECO (grant Nos. MAT2015-71070-REDC and MAT2016-75586-C4-2-P, and MALTA Consolider Team RED2018-102612-T) and Generalitat Valenciana (grant No. PROMETEO/2018/123-EFIMAT). J. Contreras-Garci ' a thanks CALSIMLAB (public grant No. ANR-11-LABX-0037-01), overseen by the French National Research Agency (ANR) as part of the Investissements d'Avenir program (grant No. ANR-11-IDEX-0004-02). M. Marque ' s acknowledges support from the ERC grant `Hecate' and computational resources provided by the UKCP consortium under EPSRC grant EP/P022561/1.Contreras-García, J.; Izquierdo-Ruiz, F.; Marqués, M.; Manjón, F. (2020). Borates or phosphates? That is the question. 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El Principio de Sustitución de Liskov

[ES] Con el estudio del principio de sustitución enunciado por Barbara Liskov en 1988, vamos a entrar en una de las facetas más controvertidas y potentes de la orientación a objetos, la herencia. Este principio intenta dictar unas reglas de diseño orientadas a la generación de unas jerarquías de clases basadas en un tipo muy concreto de herencia, la relación es_un (IsA)

Bibliometric analysis in paediatric dental journals listed in journal citation reports. Current trends

Aim The aim of this study was to analyse articles published in paediatric dental journals included in Journal Citation Reports (JCR), to determine current trends in paediatric publishing. Methods Articles included in paediatric dentistry journals in 2020 JCR were selected, published during the period 2008– 2020. After applying inclusion criteria, author-based parameters (article title, first author’s name, institution, sex and number of authors, number of affiliations, first/last author’s origin and geographic origin), and article-based parameters (article type, main topic, research design) were registered for each article. Results A total of 3,027 articles were analysed. The percentage of female authors showed an increasing positive tendency over the decade and the top producing country was the USA (16.5%). Dental surgery was the most recurrent topic (23.4%). Regarding the origin of the first author’s affiliation, 51% proceeded from the paediatric dentistry departments belonging to public institutions, with a decreasing trend in non-academic/ private affiliations. Positive and negative correlations exist between citation count and other variables. Conclusions International Journal of Paediatric Dentistry, Journal of Clinical Pediatric Dentistry, European Journal of Paediatric Dentistry and Pediatric Dentistry were the four main journals in terms of production volume, USA being the most productive country. The most recurrent topic was dental surgery, and the most common design was observational studies. Study design, geographic origin of the articles, article type and main subject of the article might predict citation.Odontologí

Enhancement of rotifer (Brachionus plicatilis) growth by using terrestrial lactic acid bacteria

17 páginas, 5 tablas, 3 figurasOne of the pathways for the entry of bacteria, both pathogenic and probiotic, into the larvae of fish hatcheries is via live prey. As a preventive measure against infections, live prey may be cultured, supplementing the food with probiotics. Some lactic acid bacteria (LAB) have been successfully used in the larviculture. In this study, the nutritional effect of seven terrestrial LAB has been studied regarding the growth of the rotifer Brachionus plicatilis. The cultures were carried out without partial renewal of the culture medium, feeding the rotifers on baker’s yeast and adding some of the species of bacteria. In all cases, the addition of the bacteria increased both the specific maximum growth rate and the maximum density obtainable in the cultures. However, the best results were obtained with the addition of Lactococcus casei ssp. casei, Pediococcus acidilactici, or Lactobacillus lactis spp lactis. The rates of growth obtained with the individual or joint addition of these three bacteria were 8–13 times greater than those obtained with the control cultures after 4–5 days’ culture. In this study, a series of kinetic models has been applied (logistic modified— Gompertz, logistic–logistic, and generalised logistic) which describes the experimental data, obtaining a set of parameters of biological significance which facilitate the optimisation of the use of these bacterial strains in the mass production of rotifers.Peer reviewe

Removal of paracetamol on biomass-derived activated carbon: Modeling the fixed bed breakthrough curves using batch adsorption experiments

The remediation of paracetamol (PA), an emerging contaminant frequently found in wastewater treatment plants, has been studied in the low concentration range (0.3–10 mg L−1) using as adsorbent a biomass-derived activated carbon. PA uptake of up to 100 mg g−1 over the activated carbon has been obtained, with the adsorption isotherms being fairly explained by the Langmuir model. The application of Reichemberg and the Vermeulen equations to the batch kinetics experiments allowed estimating homogeneous and heterogeneous diffusion coefficients, reflecting the dependence of diffusion with the surface coverage of PA. A series of rapid small-scale column tests were carried out to determine the breakthrough curves under different operational conditions (temperature, PA concentration, flow rate, bed length). The suitability of the proposed adsorbent for the remediation of PA in fixed-bed adsorption was proven by the high PA adsorption capacity along with the fast adsorption and the reduced height of the mass transfer zone of the columns. We have demonstrated that, thanks to the use of the heterogeneous diffusion coefficient, the proposed mathematical approach for the numerical solution to the mass balance of the column provides a reliable description of the breakthrough profiles and the design parameters, being much more accurate than models based in the classical linear driving force.We gratefully thank Junta de Andalucía (P09-FQM-5156) and Spanish Ministry of Economy and Competitiveness (MINECO – Spain) (Project CTQ2012-36408) and Fondo Europeo de Desarrollo Regional (FEDER – Spain) for financial support