Reaction Kinetics in the Production of Pd Nanoparticles in Reverse Microemulsions. Effect on Particle Size

In the synthesis of metallic nanoparticles in microemulsions, we hypothesized that particle size is mainly controlled by the reaction rate. Thus, the changes observed on the particle sizes as reaction conditions, such as concentrations, temperature, type of surfactant used, etc., are varied should not be correlated directly to the modification of those conditions but indirectly to the changes they produce on the reaction rates. By means of time resolved UV-vis spectroscopy, we measured the reaction rates in the production of Pd nanoparticles inside microemulsions at different reactant concentrations, keeping all the other parameters constant. The measured reaction rates were then correlated with the particle sizes measured by transmission electron microscopy (TEM). We found that nanoparticle size increases linearly as the reaction rates increases, independently of the actual reactant concentrations. We proposed that the kinetics is controlled mainly by the diffusion of the reducing agent through the surfactant monolayer covering the microemulsion membrane. With this model, we predicted that particle size should depend indirectly, via the reaction kinetics, on the micelle radius (v0 ~ r^-3), the water volume (v0~vw^3) and the total microemulsion volume (v0~vT^-3), and temperature (Arrhenius). Some of these predictions were explored in this article

La Pileta (Benaoján, Málaga) cien años después. Aportaciones al conocimiento de su secuencia arqueológica

La cueva de La Pileta es un yacimiento muy conocido por la riqueza de las manifestaciones artísticas parietales prehistóricas que atesora. Sin embargo, el conocimiento de la secuencia cronocultural documentada en las excavaciones arqueológicas llevadas a cabo en 1912 y 1942 es muy pobre. En este trabajo hacemos un repaso del registro arqueológico de La Pileta a partir de la revisión historiográfica y del estudio de los materiales depositados en el Museo de Málaga y de algunos documentos del archivo de esta institución. Los resultados, aunque limitados, permiten deducir la existencia de una secuencia más amplia de la conocida por lo general, compuesta por niveles del Paleolítico medio, Paleolítico superior; Neolítico, Calcolítico, Edad del Bronce y Edad Media

Gender differences in motivation and perception of utility of the scholar spot

El principal objetivo del estudio es analizar las diferencias entre el nivel de autodeterminación y la satisfacción de las necesidades psicológicas básicas en función del género y su incidencia sobre la percepción de utilidad del deporte. Participaron en el estudio 1897 jóvenes jugadores de baloncesto, balonmano, fútbol y voleibol (1378 chicos y 519 chicas). Diferentes instrumentos fueron utilizados para medir las distintas variables abordadas en el estudio. Los resultados mostraron que los chicos presentan puntuaciones más altas en todos los tipos de motivación y que su sentimiento de competencia es más elevado que el de las chicas. Por otro lado, la motivación autodeterminada y la satisfacción de las necesidades conducen a percibir mayor utilidad del deporte en ambos génerosThe aim of the study was to analyze the differences between self-determination level and satisfaction of the three psychological needs with respect to gender and their influence on the perception of utility of the sport. The sample comprised 1897 basketball, handball, football and volleyball young players (1378 boys and 519 girls). Different measures were used to examine the differences between the variables contained in the study. Results showed that boys were more intrinsically and extrinsically motivated and showed less a motivation than girls, as well as their scored higher in competence than girls. However, both for boys and girls, self-determined motivation and psychological needs satisfaction led to a greater perception of utility of the spor

Analysis of the group process and the performance in semiprofessional soccer

El principal objetivo del estudio es aplicar un modelo teórico analizando dos de los antecedentes de la eficacia colectiva, el clima motivacional y la cohesión grupal, y su principal consecuencia como es el rendimiento. Los participantes fueron 203 futbolistas que participaban en el grupo XIV de la Liga Nacional de Tercera División, que rellenaron diversos instrumentos para valorar el clima motivacional, la cohesión y la eficacia colectiva. Los resultados obtenidos señalan que el modelo teórico que se aplica confirma que el clima que implica a la tarea predice la cohesión grupal. Además, la cohesión tarea se manifiesta como el principal predictor de la eficacia colectiva, y ésta a su vez del rendimiento. La principal conclusión es que para optimizar la percepción de eficacia colectiva y con ello, la mejora del rendimiento, parece fundamental que los entrenadores planteen estrategias para fomentar los aspectos tarea del clima motivacional y la cohesión grupal en los jugadores.The main aim of the study was to test a theoretical model examining two of the antecedents of the collective efficacy, motivational climate and group cohesion, as well as performance as their principal consequence. Participants were 203 footballers who played in the XIV group of National League in Third Division and filled several instruments to assess motivational climate, cohesion and collective efficacy. The theoretical model showed that mastery climate predicted group cohesion. Furthermore, task cohesion emerged as the strongest predictor of collective efficacy, and this variable predicted performance. The main conclusion is that to optimize perception of collective efficacy and so, increase performance, it seems important that coaches promote strategies to enhance task related motivational climate and group cohesion in players

Phosphorus export from catchments: a global view

16 pages, figures, and tables statistics.We reviewed global P export and its controlling factors from 685 world rivers. We used available continuous (runoff, rainfall, catchment area, % land use, and population density) and discrete (runoff type, soil type, biome, dominant land use, dominant type of forest, occurrence of stagnant water bodies in catchment, and Gross Product per Capita [GPC]) variables to predict export of P fractions. P export (kg P km22 y21) spanned 6 orders of magnitude worldwide. The distribution of all fractions of P export (total P [TP], soluble reactive P [SRP], and nonSRP [dissolved organic and particle-bound P]) was right skewed. Export of nonSRP had the highest coefficient of variability, and nonSRP was the dominant part of export. The available environmental variables predicted global P export fairly well (R2 = 0.73) if total N export was included in calculations. The unexplained variance in P export might be attributed to noise in the data set, inaccuracy of measurements of environmental variables at fine scales, lack of quantitative data on anthropogenic P sources, insufficient knowledge of P behavior in catchment soils, and nonlinearity of controlling processes. P exports were highly variable among catchment types, and runoff and population density were the predictors shared by most models. P export appeared to be controlled by different sets of environmental variables in different types of catchments. Quasi-empirical, mechanistic models of P export performed better than did empirical models. Our mechanistic understanding of P export could be improved by refining current analytical methods to obtain fast and reliable values of all P fractions in aquatic ecosystems and by incorporating better and more detailed data on catchment features, anthropogenic sources of P, and instream variables in a mechanistic modelling framework.Peer reviewe

NAFO/ICES Pandalus Assessment Group Meeting, 1-4 November 2021

Report of the NAFO/ICES Pandalus Assessment Group Meeting held by WebEx from 1 to 4 November 2021Versión del editor

Influence of coaches training on athletes motivation

El objetivo del estudio era conocer la influencia de las formaciones académica y federativa de los entrenadores sobre los niveles de motivación, diversión, aburrimiento e intención de persistencia en jóvenes deportistas. Para ello, participaron 432 jóvenes con edades entre 10 y 16 años (M = 13,44; DT = 2,92), pertenecientes a disciplinas deportivas individuales (n = 162) y colectivas (n = 270), de género masculino (n = 245) y femenino (n = 187), seleccionados mediante un muestreo por conglomerados. También, participaron 88 entrenadores deportivos, con edades entre los 20 y 56 años (M = 35,79; DT = 9,58). Se llevó a cabo un análisis de diferencias en función de la cualificación académica y federativa de los entrenadores. Los resultados señalaron que los deportistas dirigidos por entrenadores sin formación federativa presentaban mayores niveles de desmotivación. Asimismo, los deportistas entrenados por técnicos sin titulación académica obtuvieron mayores puntuaciones en las regulaciones extrínsecas (identificada y externa). Por tanto, los hallazgos respaldan parcialmente la relevancia de la formación de los entrenadores, obteniéndose diferencias en regulaciones alejadas del máximo nivel de autodeterminación (externa), desmotivación y aburrimientoThe aim of the study was to examine the influence of the coaches´ academic and federative training on motivation, enjoyment, boredom and intention to persist levels in youth athletes. Participants were 432 youth athletes (male = 245, female = 187) ranged from 10 to 16 years old (M = 13.44; SD = 2.92) who participated in individual (n = 163) and collectives sports (n = 270) selected by cluster sampling. Moreover, 88 sport coaches, ranged from 20 to 56 years old (M = 35,79; SD = 9,58), participated in the study. An analysis of differences with regard to academic and federative coaches´ qualification was conducted. Results revealed that athletes trained by coaches without federative training showed greater amotivation levels. Moreover, individuals trained by coaches without academic qualification had higher scores in extrinsic regulation (identified and external). Therefore, findings partially supported the relevance of coaches’ qualification levels, due to the differences found in some extrinsic regulations (external), amotivation and boredo

Results from Bottom Trawl Survey on Flemish Cap of June-July 2016.

A stratified random bottom trawl survey on Flemish Cap was carried out from June 22th to July 23th 2016. The area surveyed was extended up to depths of 800 fathoms (1460 meters) following the same procedures as in previous years and 181 fishing stations planned. The survey was carried out by the R/V Vizconde de Eza with the usual survey gear (Lofoten). A total of 181 valid hauls were made by the vessel R/V Vizconde de Eza, 120 up to 730 meters depth and 61 up to 1460 meters. Survey results including abundance indices of the main commercial species and age distributions for cod, redfish, American plaice, Greenland halibut, roughhead grenadier and shrimp are presented. The general indexes for this year are estimated taken into account the traditional swept area (strata 1- 19, up to depths of 730 m.) and the total area surveyed (strata 1-34, up to depths of 1460 m.).Postprin