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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Schiavinatoite, (Nb,Ta)BO4, the Nb analogue of behierite. European Journal of Mineralogy, 13(1), 159-165. doi:10.1127/0935-1221/01/0013-0159Depero, L. E., & Sangaletti, L. (1997). Cation Sublattice and Coordination Polyhedra inABO4Type of Structures. Journal of Solid State Chemistry, 129(1), 82-91. doi:10.1006/jssc.1996.7234Errandonea, D., & Manjón, F. J. (2008). Pressure effects on the structural and electronic properties of ABX4 scintillating crystals. Progress in Materials Science, 53(4), 711-773. doi:10.1016/j.pmatsci.2008.02.001Fukunaga, O., & Yamaoka, S. (1979). Phase transformations in ABO 4 type compounds under high pressure. Physics and Chemistry of Minerals, 5(2), 167-177. doi:10.1007/bf00307551Gázquez, J. L., & Ortiz, E. (1984). Electronegativities and hardnesses of open shell atoms. The Journal of Chemical Physics, 81(6), 2741-2748. doi:10.1063/1.447946Geerlings, P., De Proft, F., & Langenaeker, W. (2003). Conceptual Density Functional Theory. 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E., Khritokhin, N. A., & Andreev, O. V. (2012). Structure maps of ABX4 inorganic compounds. Russian Journal of Inorganic Chemistry, 57(12), 1584-1587. doi:10.1134/s0036023612120133Léger, J. M., Haines, J., Chateau, C., Bocquillon, G., Schmidt, M. W., Hull, S., … Marchand, R. (2001). Phosphorus oxynitride PON, a silica analogue: structure and compression of the cristobalite-like phase; P  - T phase diagram. Physics and Chemistry of Minerals, 28(6), 388-398. doi:10.1007/s002690100161Liu, L. (1982). Phase transformations in MSiO4 compounds at high pressures and their geophysical implications. Earth and Planetary Science Letters, 57(1), 110-116. doi:10.1016/0012-821x(82)90177-7Martín Pendás, A., Costales, A., Blanco, M. A., Recio, J. M., & Luaña, V. (2000). Local compressibilities in crystals. Physical Review B, 62(21), 13970-13978. doi:10.1103/physrevb.62.13970Monkhorst, H. J., & Pack, J. D. (1976). Special points for Brillouin-zone integrations. 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Physical Chemistry Chemical Physics, 14(35), 12165. doi:10.1039/c2cp41395gPauling, L. (1929). THE PRINCIPLES DETERMINING THE STRUCTURE OF COMPLEX IONIC CRYSTALS. Journal of the American Chemical Society, 51(4), 1010-1026. doi:10.1021/ja01379a006Pauling, L. (1960). The Nature of the Chemical Bond and the Structure of Molecules and Crystals: An Introduction to Modern Structural Chemistry, 3rd ed., pp. 543-562. Ithaca: Cornell University Press.Perdew, J. P., Burke, K., & Ernzerhof, M. (1996). Generalized Gradient Approximation Made Simple. Physical Review Letters, 77(18), 3865-3868. doi:10.1103/physrevlett.77.3865Rahm, M., Zeng, T., & Hoffmann, R. (2018). Electronegativity Seen as the Ground-State Average Valence Electron Binding Energy. Journal of the American Chemical Society, 141(1), 342-351. doi:10.1021/jacs.8b10246Range, K.-J., Wildenauer, M., & Heyns, A. M. (1988). Extremely Short Non-Bonding Oxygen?Oxygen Distances: The Crystal Structures of NbBO4, NaNb3O8, and NaTa3O8. 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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

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

Low variability of single-molecule conductance assisted by bulky metal-molecule contacts

A detailed study of the trimethylsilylethynyl moiety, –C[triple bond]CSiMe3 (TMSE) , as an anchoring group in metalmoleculemetal junctions, using a combination of experiment and density functional theory is presented. It is shown that the TMSE anchoring group provides improved control over the molecule-substrate arrangement within metalmoleculemetal junctions, with the steric bulk of the methyl groups limiting the number of highly transmissive binding sites at the electrode surface, resulting in a single sharp peak in the conductance histograms recorded by both the in situ break junction and I(s) STM techniques. As a consequence of the low accessibility of the TMSE group to surface binding configurations of measurable conductance, only about 10% of gold break junction formation cycles result in the clear formation of molecular junctions in the experimental histograms. The DFT-computed transmission characteristics of junctions formed from the TMSE-contacted oligo(phenylene)ethynylene (OPE)-based molecules described here are dominated by tunneling effects through the highest-occupied molecular orbitals (HOMOs). This gives rise to similar conductance characteristics in these TMSE-contacted systems as found in low conductance-type junctions based on comparably structured OPE-derivatives with amine-contacts that also conduct through HOMO-based channels.R. R. F. thanks the Consejería de Educación del Principado de Asturias for a Severo Ochoa grant (BP11-069). V. M. G.-S. thanks the Spanish Ministerio de Economía y Competitividad for a Ramón y Cajal fellowship (RYC-2010-06053). R. R. F., J. F. and V. M. G.-S. wish to acknowledge financial support from the Spanish grant FIS2012-34858 and the Marie Curie Network MOLESCO. P. C. and S. M. are grateful for financial assistance from the Ministerio de Economía y Competitividad of Spain in the framework of the project CTQ2012-33198 as well as the award of the CTQ2013-50187-EXP grant. H. M. O., P. C., and S. M. thank the support from DGA and Fondos FEDER for funding through the Platon research group. H. M. O. is also grateful for financial assistance from the Secretaría Nacional de Educación Superior, Ciencia, Tecnología e Innovaciín from Ministerio de Educación (Ecuador). S. M. thanks the Ministerio de Educación from Spain for financial support through the framework of the Campus de Excelencia Internacional, CEI Iberus. S. J. H., R. J. N., P. J. L. and S. M.-G. thank the EPSRC for funding (EPSRC grants EP/K007785/1, EP/H035184/1, EP/K007548/1, EP/H005595/1). P. J. L. holds an Australian Research Council Future Fellowship (FT120100073) and gratefully acknowledges funding for this work from the ARC (DP140100855).Peer Reviewe

Higher education segregation in Spain: Gender constructs and social background

The waning influence of ascriptive factors on occupational status has been related to the expansion of higher education systems and economic modernisation. The theory of Effectively Maintained Inequality observes that the horizontal stratification of university degrees is a strategy of social differentiation used mainly by the most advantaged social class to access the occupations that are better valued in the labour market. This article verifies the effectively maintained inequality theory by means of a statistical analysis of selected degrees, differentiated by gender and social class, carried out in a Spanish university during the period of expansion and consolidation of the higher education system. The results confirm the theory, but they are partially conditioned by the vertical stratification that alters the composition by gender of the contingent of students of less advantaged social class, in which women present a greater tendency to choose degrees that are less valued by the market

MicroRNA 7 Impairs Insulin Signaling and Regulates Aβ Levels through Posttranscriptional Regulation of the Insulin Receptor Substrate 2, Insulin Receptor, Insulin-Degrading Enzyme, and Liver X Receptor Pathway

Brain insulin resistance is a key pathological feature contributing to obesity, diabetes, and neurodegenerative disorders, including Alzheimer’s disease (AD). Besides the classic transcriptional mechanism mediated by hormones, posttranscriptional regulation has recently been shown to regulate a number of signaling pathways that could lead to metabolic diseases. Here, we show that microRNA 7 (miR-7), an abundant microRNA in the brain, targets insulin receptor (INSR), insulin receptor substrate 2 (IRS-2), and insulin-degrading enzyme (IDE), key regulators of insulin homeostatic functions in the central nervous system (CNS) and the pathology of AD. In this study, we found that insulin and liver X receptor (LXR) activators promote the expression of the intronic miR-7-1 in vitro and in vivo, along with its host heterogeneous nuclear ribonucleoprotein K (HNRNPK) gene, encoding an RNA binding protein (RBP) that is involved in insulin action at the posttranscriptional level. Our data show that miR-7 expression is altered in the brains of diet-induced obese mice. Moreover, we found that the levels of miR-7 are also elevated in brains of AD patients; this inversely correlates with the expression of its target genes IRS-2 and IDE. Furthermore, overexpression of miR-7 increased the levels of extracellular Aβ in neuronal cells and impaired the clearance of extracellular Aβ by microglial cells. Taken together, these results represent a novel branch of insulin action through the HNRNPK–miR-7 axis and highlight the possible implication of these posttranscriptional regulators in a range of diseases underlying metabolic dysregulation in the brain, from diabetes to Alzheimer’s disease