Is the largest aqueous gold cluster a superatom complex? Electronic structure & optical response of the structurally determined Au146(pMBA)57

The new water-soluble gold cluster Au146(pMBA)57, the structure of which has been recently determined at sub-atomic resolution by Vergara et al. [1], is the largest aqueous gold cluster ever structurally determined and likewise the smallest cluster with a stacking fault. The core presents a twinned truncated octahedron, while additional peripheral gold atoms follow a C2 rotational symmetry. According to the usual counting rules of the superatom complex (SAC) model, the compound attains a number of 92 SAC electrons if the overall net charge is 3- (three additional electrons). As this is the number of electrons required for a major shell closing, the question arises if Au146(pMBA)57 should be regarded as a superatom complex. Starting from the experimental coordinates we have analyzed the structure using density-functional theory. The optimized (relaxed) structure retains all the connectivity of the experimental coordinates, while removing much of its irregularities in interatomic distances, thereby enhancing the C2-symmetry feature. Analyzing the angular-momentum projected states, we show that, despite a small gap, the electronic structure does not exhibit SAC model character. In addition, optical absorption spectra are found to be relatively smooth compared to the example of the Au144(SR)60 cluster. The Au146(SR)57 cluster does not derive its stability from SAC character; it cannot be considered a superatom complex

Natural selection on plant resistance to herbivores in the native and introduced range

. When plants are introduced into new regions, the absence of their co-evolved natural enemies can result in lower levels of attack. As a consequence of this reduction in enemy pressure, plant performance may increase and selection for resistance to enemies may decrease. In the present study, we compared leaf damage, plant size and leaf trichome density, as well as the direction and magnitude of selection on resistance and plant size between non-native (Spain) and native (Mexico) populations of Datura stramonium. This species was introduced to Spain about five centuries ago and constitutes an ideal system to test four predictions of the enemy release hypothesis. Compared with native populations, we expected Spanish populations of D. stramonium to have (i) lower levels of foliar damage; (ii) larger plant size; (iii) lower leaf trichome density that is unrelated to foliar damage by herbivores; and (iv) weak or no selection on resistance to herbivores but strong selection on plant size. Our results showed that, on average, plants from non-native populations were significantly less damaged by herbivores, were less pubescent and were larger than those from native populations. We also detected different selection regimes on resistance and plant size between the non-native and native ranges. Positive selection on plant size was detected in both ranges (though it was higher in the non-native area), but consistent positive selection on relative resistance was detected only in the native range. Overall, we suggest that changes in selection pressure on resistance and plant size in D. stramonium in Spain are a consequence of ‘release from natural enemies’

Improved graphene blisters by ultrahigh pressure sealing

Graphene is a very attractive material for nanomechanical devices and membrane applications. Graphene blisters based on silicon oxide micro-cavities are a simple but relevant example of nanoactuators. A drawback of this experimental set up is that gas leakage through the graphene-SiO2 interface contributes significantly to the total leak rate. Here we study the diffusion of air from pressurized graphene drumheads on SiO2 micro-cavities and propose a straightforward method to improve the already strong adhesion between graphene and the underlying SiO2 substrate, resulting in reduced leak rates. This is carried out by applying controlled and localized ultrahigh pressure (> 10 GPa) with an Atomic Force Microscopy diamond tip. With this procedure, we are able to significantly approach the graphene layer to the SiO2 surface around the drumheads, thus enhancing the interaction between them allowing us to better seal the graphene-SiO2 interface, which is reflected in up to ~ 4 times lower leakage rates. Our work opens an easy way to improve the performance of graphene as a gas membrane on a technological relevant substrate such as SiO2.Comment: pages 19, 4 figures + supplementary informatio

Aproximación historiográfica a la restauración patrimonial de carácter historicista en España: desde sus albores a la actualidad

The article aims at a historiographic approach to the history of heritage restoration from its origins to the present day, with a special emphasis on the «historical fake», through literature review and analysis of different case studies. The concept emerged in Europe in the middle of the 20th century, but its appearance in the practical field dates to the first romantic restorations. «Unity of style» and its struggle against the anti–restorative posture will mark the nineteenth century until the new century brings the triumph of the conservative tendency, nuanced in the following by several authors until reaching an aesthetic–historical balance. The Spanish panorama follows this evolution until the Franco dictatorship imposes again the historicist values, a position that will begin to change at the dawn of democracy. Despite this theoretical advance, the current situation is dominated by disparate criteria that cause a heterogeneous restorative landscape.El artículo tiene como objetivo la aproximación historiográfica a la historia de la restauración patrimonial desde sus orígenes hasta nuestros días, con especial énfasis en el «falso histórico», mediante la revisión bibliográfica y el análisis de distintos casos de estudio. El concepto surge en Europa en pleno siglo XX, pero su aparición en el terreno práctico se remonta a las primeras restauraciones románticas. La «Unidad de estilo» y su lucha contra la postura antirrestauradora marcarán el siglo XIX hasta que la nueva centuria traiga consigo el triunfo de la tendencia conservadora, matizada en lo sucesivo por diversos autores hasta llegar a un equilibrio estético–histórico. El panorama español sigue esta evolución hasta que la Dictadura Franquista impone de nuevo los valores historicistas, postura que empezará a cambiar en los albores de la democracia. A pesar de este avance teórico, la actualidad aparece dominada por criterios dispares que provocan un heterogéneo panorama restaurador

Association Between Physical Activity and Odds of Chronic Conditions Among Workers in Spain

Introduction: Prevention of chronic conditions is a major public health challenge, and achieving minimum recommended levels of physical activity aids in reaching this objective. The aim of our study was to investigate whether levels of physical activity were associated with the prevalence of common chronic conditions among the Spanish workforce. Methods: We retrieved data from the Spanish National Health Survey 2017 (N = 9,695) in which the mean age of participants was 44.4 (standard deviation, 10.4 y), and 47.4% were women. Workers self-reported a set of 6 chronic conditions (ie, chronic low-back pain, chronic neck pain, diabetes, hypertension, depression, and anxiety), and we used the International Physical Activity Questionnaire short form to estimate physical activity. We performed multivariable logistic regression adjusted for possible confounders to assess associations between physical activity and chronic conditions. Results: The final adjusted model showed that performing less than 600 metabolic equivalent-minutes per week of physical activity was associated with significantly increased odds for chronic conditions (adjusted odds ratio [aOR] = 1.18; 95% CI, 1.07–1.30). Of the sex and age subgroups analyzed, this association was significant in men aged 17 to 44 (aOR = 1.21; 95% CI, 1.00–1.46). Among chronic conditions, low-back pain and anxiety were associated with low levels of physical activity, whereas covariates such as body mass index, smoking habits, education level, and occupational class had an important influence on the association between physical activity and chronic conditions. Conclusion: Results suggest that achieving sufficient physical activity could reduce chronic conditions among Spanish workers

Separación de Circones: Primer Informe

Fil: López, Faustino A. Servicio Geológico Minero Argentino. Instituto de Tecnología Minera; Argentina.Fil: Romano, Andrea, L. Servicio Geológico Minero Argentino. Instituto de Tecnología Minera; Argentina.Fil: Cozzi, Guillermo. Servicio Geológico Minero Argentino. Instituto de Tecnología Minera; Argentina.En el marco del proyecto del Laboratorio de Geoquímica Isotópica, se realizan los primeros intentos de preparación de muestra. En este trabajo se utilizan exclusivamente las instalaciones del SEGEMAR ubicadas en el parque tecnológico Migueletes, edificios 25 y 14. Se pretende registrar la capacidad real, actual del SEGEMAR para procesar una muestra en bruto y extraer de la misma, una cantidad suficiente de circones para ser analizados por el LA-MCICP-MS adquirido por el organismo, ya sea para datación (U-Pb) o para análisis de elementos traza. Tanto los criterios de selección del material en bruto como los métodos de extracción y transporte adecuados para realizar una separación de circones exitosa, no se analizan en este informe. Tampoco se realizan análisis químicos ni petrográficos. Se comenzó el proceso con una roca previamente molida hasta tamaños de entre 5 a 20 mm y, aunque la capacidad de moler una roca de mayor tamaño se encuentra disponible en SEGEMAR, no se analiza en este informe. Queda pendiente también el armado de la montura, ya sea en pastilla epoxi o en corte delgado, estos aspectos están siendo analizados en conjunto con el proveedor del equipo

Immediate Impact of the COVID-19 Confinement on Physical Activity Levels in Spanish Adults

Enacted measures to control the spread of COVID-19 disease such as compulsory confinement may influence health behaviors. The present study investigated changes in physical activity (PA) levels during the first days of confinement. Using an online survey, the Spanish population (n = 2042, 54% women, age 35.9 (SD 13.6) years) replied to questions concerning sociodemographic characteristics as well as PA behavior before and during the first week of enacted isolation. Physical activity vital sign (PAVS) short form was used to estimate weekly minutes of PA before and during the isolation period. Statistical analysis used the following tests: Mc Nemar Chi-squared tests, independent and paired samples t-test, and effect size (Cohen’s d). During the first week of confinement, participants reduced their weekly PA levels by 20% (~45.2 weekly minutes (95% CI: 37.4−53.0)). This led to a decrease from 60.6% to 48.9% (difference: 11.7%) (p < 0.0001) in the number of participants meeting the recommended World Health Organization (WHO) PA levels. Subgroups including men, participants aged 43 or over, and those not holding a university degree had the greatest reductions in both weekly minutes of PA and adherence to guidelines. The PA levels of the Spanish population generally declined during the first days of COVID-19 confinement

Comparative genomics of canine hemoglobin genes reveals primacy of beta subunit delta in adult carnivores

Sequences of primers used for PCR and sequencing studies. (XLSX 45 kb

Corrigendum: COVID-19 Confinement and Health Risk Behaviors in Spain

In the original article, the reference for Chen et al. (2009) was incorrectly written as “Chen, P., Mao, L., Nassis, G. P., Harmer, P., Ainsworth, B. E., and Li, F. (2009). Wuhan coronavirus (2019-nCoV): the need to maintain regular physical activity while taking precautions. J. Sport Health Sci. 9, 103–104. doi: 10.1016/j.jshs.2020.02.001”. It should be “Chen, P., Mao, L., Nassis, G. P., Harmer, P., Ainsworth, B. E., and Li, F. (2020). Coronavirus disease (COVID-19): The need to maintain regular physical activity while taking precautions. J. Sport Health Sci. 9, 103–104. doi: 10.1016/j.jshs.2020.02.001”. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated

A family of Nikishin systems with periodic recurrence coefficients

Suppose we have a Nikishin system of $p$ measures with the $k$th generating measure of the Nikishin system supported on an interval \Delta_k\subset\er with $\Delta_k\cap\Delta_{k+1}=\emptyset$ for all $k$. It is well known that the corresponding staircase sequence of multiple orthogonal polynomials satisfies a $(p+2)$-term recurrence relation whose recurrence coefficients, under appropriate assumptions on the generating measures, have periodic limits of period $p$. (The limit values depend only on the positions of the intervals $\Delta_k$.) Taking these periodic limit values as the coefficients of a new $(p+2)$-term recurrence relation, we construct a canonical sequence of monic polynomials $\{P_{n}\}_{n=0}^{\infty}$, the so-called \emph{Chebyshev-Nikishin polynomials}. We show that the polynomials $P_{n}$ themselves form a sequence of multiple orthogonal polynomials with respect to some Nikishin system of measures, with the $k$th generating measure being absolutely continuous on $\Delta_{k}$. In this way we generalize a result of the third author and Rocha \cite{LopRoc} for the case $p=2$. The proof uses the connection with block Toeplitz matrices, and with a certain Riemann surface of genus zero. We also obtain strong asymptotics and an exact Widom-type formula for the second kind functions of the Nikishin system for $\{P_{n}\}_{n=0}^{\infty}$.Comment: 30 pages, minor change