2,421 research outputs found
Fabricación y caracterización de composites de ácido poliláctico reforzados con madera de olivo
En esta investigación se ha reforzado el biopolímero ácido poliláctico con madera de olivo obteniéndose un composite que mejora las propiedades y a la vez cumple con los requisitos medioambientales. El proceso ha consistido en un mezclado automático del PLA, fibra de madera y 10% de aditivo, seguido de un proceso de inyección. El porcentaje de fibra de madera de olivo adicionada han sido del 20% y se ha empleado madera sin tratar y tratada con álcali. Se han determinado las propiedades mecánicas y térmicas de los composites y se ha evaluado la influencia de la exposición ultravioleta en el comportamiento mecánico
Microbial mediated formation of Fe-carbonate minerals under extreme acidic conditions
Discovery of Fe-carbonate precipitation in Rio Tinto, a shallow river with very acidic waters, situated in Huelva, South-western Spain, adds a new dimension to our understanding of carbonate formation. Sediment samples from this low-pH system indicate that carbonates are formed in physico-chemical conditions ranging from acid to neutral pH. Evidence for microbial mediation is observed in secondary electron images (Fig. 1), which reveal rod-shaped bacteria embedded in the surface of siderite nanocrystals. The formation of carbonates in Rio Tinto is related to the microbial reduction of ferric iron coupled to the oxidation of organic compounds. Herein, we demonstrate for the first time, that Acidiphilium sp. PM, an iron-reducing bacterium isolated from Rio Tinto, mediates the precipitation of siderite (FeCO3) under acidic conditions and at a low temperature (30°C). We describe nucleation of siderite on nanoglobules in intimate association with the bacteria cell surface. This study has major implications for understanding carbonate formation on the ancient Earth or extraterrestrial planets.European research project ERC-250350/IPBSL. A.S.-N.acknowledges support from the P11-RNM-7067 (Junta de Andaluc a-C.E.I.C.-S.G.U.I.T.) projectPeer Reviewe
The Type 1 and Type 2 AGN dichotomy according to their ZTF optical variability
The scarce optical variability studies in spectrally classified Type 2 active
galactic nuclei (AGNs) have led to the discovery of anomalous objects that are
incompatible with the simplest unified models (UM). This paper focuses on the
exploration of different variability features that allows to separate between
obscured, Type 2 AGNs, and the variable, unobscured Type 1s. We analyse
systematically the Zwicky Transient Facility, 2.5 years long light curves of ~
15000 AGNs from the Sloan Digital Sky Survey Data Release 16, which are
generally considered Type 2s due to the absence of strong broad emission lines
(BELs). Consistently with the expectations from the UM, the variability
features are distributed differently for distinct populations, with spectrally
classified weak Type 1s showing 1 order of magnitude larger variances than the
Type 2s. We find that the parameters given by the damped random walk model
leads to broader H{\alpha} equivalent width for objects with {\tau}_g > 16 d
and long term structure function SF{\infty},g> 0.07 mag. By limiting the
variability features, we find that ~ 11 per cent of Type 2 sources show
evidence for optical variations. A detailed spectral analysis of the most
variable sources (~1 per cent of the Type 2 sample) leads to the discovery of
misclassified Type 1s with weak BELs and changing-state candidates. This work
presents one of the largest systematic investigations of Type 2 AGN optical
variability to date, in preparation for future large photometric surveys.Comment: Accepted for publication in MNRAS. 13 pages, 9 figure
Synthesis of chitosan oligomers/propolis/silver-nanoparticles composite systems and study of their activity against Diplodia seriata
The synthesis and characterization of composites of oligomeric chitosan with propolis extract which allow the incorporation of a third component (silver nanoparticles) are reported, together with their application in aqueous or hydroalcoholic solutions with a view to the formation of adhesive substances or nanofilms for the protection of vineyards against harmful xylophagous fungi. The antimicrobial properties of the association of the two biological products or those resulting from the incorporation of silver nanoparticles (NPs) are studied and discussed. The efficacy of the chitosan oligomers/propolis/silver NPs ternary system is assessed in vitro for Diplodia fungi. A preliminary study on the convenience of replacing propolis with gentisic acid is also presented
Hygienization and control of Diplodia seriata fungus in vine pruning waste composting and its seasonal variability in open and closed systems
After the ban on sodium arsenite, waste management alternatives to the prevalent burning method, such as the hygienization and biodegradation in solid phase by composting, are required for the pruned material from grapevines affected by various fungi. In this work the dynamics of a fungus associated with vine decay (Diplodia seriata) during the composting process of a mixture of laying hen manure and vine pruning waste (2:1 w/w) have been investigated in an open pile and a discontinuous closed biodigester. Through the optimization of the various physical–chemical parameters, hygienization of the infected waste materials was attained, yielding class-A organo-mineral fertilizers. Nevertheless, important differences in the efficiency of each system were observed: whereas in the open pile it took 10 days to control D. seriata and 35 additional composting days to achieve full inactivation, in the discontinuous biodigester the fungus was entirely inactivated within the first 3–7 days. Finally, the impact of seasonal variability was assessed and summer temperatures shown to have greater significance in the open pile
UAV Detection of sinapis arvensis infestation in alfalfa plots using simple vegetation indices from conventional digital cameras
Producción CientíficaUnmanned Aerial Vehicles (UAVs) offer excellent survey capabilities at low cost to provide farmers with information about the type and distribution of weeds in their fields. In this study, the problem of detecting the infestation of a typical weed (charlock mustard) in an alfalfa crop has been addressed using conventional digital cameras installed on a lightweight UAV to compare RGB-based indices with the widely used Normalized Difference Vegetation Index (NDVI) index. The simple (R−B)/(R+B) and (R−B)/(R+B+G) vegetation indices allowed one to easily discern the yellow weed from the green crop. Moreover, they avoided the potential confusion of weeds with soil observed for the NDVI index. The small overestimation detected in the weed identification when the RGB indices were used could be easily reduced by using them in conjunction with NDVI. The proposed methodology may be used in the generation of weed cover maps for alfalfa, which may then be translated into site-specific herbicide treatment maps.Unión Europea (project LIFE11 ENV/ES/000535
Effectiveness of the mantente REAL program for preventing alcohol use in spanish adolescents
Mantente REAL is a school-based universal program to prevent drug use and other problematic behaviors specifically
designed to be implemented in schools at the beginning of adolescence. This program, which is a culturally adapted
version of the Keepin’ it REAL intervention, focuses on skills training for resisting social pressure to use drugs and
improving psychosocial development. This study aims to evaluate the effectiveness of Mantente REAL on alcohol use in
the Spanish context. The sample was composed of 755 adolescents from 12 state secondary schools in Spain, aged 11 to
15 (M = 12.24, SD = 0.56), 47.1% females. The 12 schools were randomly assigned to control and experimental groups, six
to each condition. Pre-test and post-test questionnaires data were collected to evaluate the effectiveness of the program.
The results indicated that a culturally adapted version of Mantente REAL was effective in preventing alcohol use among
youth from northern and southern Spain. Students participating in the program demonstrated changes in the desired
direction on alcohol frequency and intoxication episodes. Implications of these results regarding intervention programs
aimed at preventing substance use in adolescence are discussed“Mantente REAL” es un programa universal que utiliza la escuela para prevenir el consumo de drogas y otras conductas
problemáticas diseñado específicamente para ser implementado en las escuelas al comienzo de la adolescencia. Este
programa, que es una versión culturalmente adaptada de la intervención Keepin’ it REAL, se centra en el entrenamiento
de habilidades para resistir la presión social para consumir drogas y mejorar el desarrollo psicosocial. Este estudio tiene
como objetivo evaluar la eficacia de “Mantente REAL” en el consumo de alcohol en el contexto español. La muestra
estuvo compuesta por 755 adolescentes de 12 escuelas secundarias públicas en España, de 11 a 15 años (M = 12.24,
DT = 0.56), el 47.1% mujeres. Las 12 escuelas fueron asignadas aleatoriamente a grupo control y experimental, seis en
cada condición. Los datos se recopilaron a través de cuestionarios antes y después de la intervención para evaluar la
eficacia del programa. Los resultados indicaron que la versión culturalmente adaptada de “Mantente REAL” fue eficaz
para prevenir el consumo de alcohol entre los jóvenes del norte y sur de España. Los estudiantes que participaron en
el programa demostraron cambios en la dirección deseada en la frecuencia del alcohol y los episodios de intoxicación.
Se discuten las implicaciones de estos resultados con respecto a los programas de intervención destinados a prevenir
el consumo de sustancias en la adolescenciaThis study was funded by the Global Center for Applied Health Research (Arizona State University) and supported by the Programa de Axudas á etapa posdoutoral da Xunta de Galicia (Consellería de Cultura, Educación e Ordenación Universitaria) and by FEDER/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación (Grant PSI2015-65766-R) – under the Axuda para a consolidación e estruturación de unidades de investigación competitivas e outras accións de fomento nas universidades do SUG (GRC, 2018)S
A Newborn AGN in a Starforming Galaxy
We report on the finding of a newborn AGN, i.e. current AGN activity in a
galaxy previously classified as non-active, and characterize its evolution.
Black hole ignition event candidates were selected from a parent sample of
spectrally classified non-active galaxies (2.394.312 objects), that currently
show optical flux variability indicative of a type I AGN, according to the
ALeRCE light curve classifier. A second epoch spectrum for a sample of
candidate newborn AGN were obtained with the SOAR telescope to search for new
AGN features. We present spectral results for the most convincing case of new
AGN activity, for a galaxy with a previous star-forming optical classification,
where the second epoch spectrum shows the appearance of prominent, broad Balmer
lines without significant changes in the narrow line flux ratios. Long term
optical lightcurves show a steady increase in luminosity starting 1.5 years
after the SDSS spectrum was taken and continuing for at least 7 years. MIR
colors from the WISE catalog have also evolved from typical non active galaxy
colors to AGN-like colors and recent X-ray flux detections confirm its AGN
nature.Comment: Accepted for publication in A&A Letter
Protection of Possessors in Classical Roman Law -From the Viewpoint of Buyer Protection- (2)
We studied the formation of Mg-rich carbonate in culture experiments using different aerobic bacterial strains and aqueous Mg/Ca ratios (2 to 11.5) at Earth surface conditions. These bacteria promoted the formation of microenvironments that facilitate the precipitation of mineral phases (dolomite, huntite, high Mg-calcite and hydromagnesite) that were undersaturated in the bulk solution or kinetically inhibited. Dolomite, huntite, high Mg-calcite, hydromagnesite and struvite precipitated in different proportions and at different times, depending on the composition of the medium. The Mg content of dolomite and calcite decreased with an increasing Ca concentration in the medium. The stable carbon isotope composition of the Mg-rich carbonate precipitates reflected the isotope composition of the organic compounds present in the media, suggesting that microbial metabolism strongly influenced the carbon isotope composition of biomediated carbonates. We observed that Ca-enriched carbonate precipitates have relatively low carbon isotope composition. These results provide insights into the mechanism(s) of carbonate formation in natural systems, and they are of fundamental importance for understanding modern environments in which carbonate minerals form as a window into the geologic past
Gender differences in adaptation to heat in Spain (1983-2018)
In Spain the average temperature has increased by 1.7 °C since pre-industrial times. There has been an increase in heat waves both in terms of frequency and intensity, with a clear impact in terms of population health. The effect of heat waves on daily mortality presents important territorial differences. Gender also affects these impacts, as a determinant that conditions social inequalities in health. There is evidence that women may be more susceptible to extreme heat than men, although there are relatively few studies that analyze differences in the vulnerability and adaptation to heat by sex. This could be related to physiological causes. On the other hand, one of the indicators used to measure vulnerability to heat in a population and its adaptation is the minimum mortality temperature (MMT) and its temporal evolution. The aim of this study was to analyze the values of MMT in men and women and its temporal evolution during the 1983-2018 period in Spain's provinces. An ecological, longitudinal retrospective study was carried out of time series data, based on maximum daily temperature and daily mortality data corresponding to the study period. Using cubic and quadratic fits between daily mortality rates and the temperature, the minimum values of these functions were determined, which allowed for determining MMT values. Furthermore, we used an improved methodology that provided for the estimation of missing MMT values when polynomial fits were inexistent. This analysis was carried out for each year. Later, based on the annual values of MMT, a linear fit was carried out to determine the rate of evolution of MMT for men and for women at the province level. Average MMT for all of Spain's provinces was 29.4 °C in the case of men and 28.7 °C in the case of women. The MMT for men was greater than that of women in 86 percent of the total provinces analyzed, which indicates greater vulnerability among women. In terms of the rate of variation in MMT during the period analyzed, that of men was 0.39 °C/decade, compared to 0.53 °C/decade for women, indicating greater adaptation to heat among women, compared to men. The differences found between men and women were statistically significant. At the province level, the results show great heterogeneity. Studies carried out at the local level are needed to provide knowledge about those factors that can explain these differences at the province level, and to allow for incorporating a gender perspective in the implementation of measures for adaptation to high temperatures.The authors wish to thank the funding provided by the ENPY 304/20, ENPY 376/18 and ENPY 107/18 projects of the Carlos III Health Institute III (ISCIII). They also wish to thank the UNED for funding this publication in open access.S
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