Hot carrier and hot phonon coupling during ultrafast relaxation of photoexcited electrons in graphene

We study, by means of a Monte Carlo simulator, the hot phonon effect on the relaxation dynamics in photoexcited graphene and its quantitative impact as compared to considering an equilibrium phonon distribution. Our multi-particle approach indicates that neglecting the hot phonon effect significantly underestimates the relaxation times in photoexcited graphene. The hot phonon effect is more important for a higher energy of the excitation pulse and photocarrier densities between $1$ and $3\times 10^{12} \mathrm{~cm}^{-2}$. Acoustic intervalley phonons play a non-negligible role, and emitted phonons with wavelengths limited up by a maximum (determined by the carrier concentration) induce a slower carrier cooling rate. Intrinsic phonon heating is damped in graphene on a substrate due to additional cooling pathways, with the hot phonon effect showing a strong inverse dependence with the carrier density.Comment: 12 pages, 5 figure

Paleomagnetic resu]ts of Jurassic rocks from Siena Harana

Los estudios paleomagnéticos en las Cordilleras Béticas empiezan a ser hoy en día numerosos. Los trabajos realizados hasta el presente tienen en común el que todos ellos indican la existencia de rotaciones, algunas de ellas muy importantes en magnitud, y la mayoría en sentido horario. Los vectores paleomagnéticos determinados han sido utilizados para establecer diferentes modelos cinemáticos. La mayoría de ellos postulan que las rotaciones observadas son acomodadas por el movimiento de fallas de salto en dirección o bien, en otros y no tan numerosos casos, por cabalgamientos.A continuación presentaremos los resultados de un estudio paleomagnético realizado en dos unidades alóctonas, una del Subbético Interno y otra de la Dorsal. El objetivo planteado al iniciar esta investigación fue el detenninar las características paleomagnéticas de los materiales elegidos y en segundo lugar establecer la existencia o no de rotaciones. El área escogida es Sierra Jarana, que se encuentra situada a unos 20 km al NNE de Granada, en el límite entre las zonas Internas y Externas de las Cordilleras Béticas. En esta sierra se han muestreado dos unidades: la Unidad de Sierra Harana y la Unidad de Cañamaya. Dichas unidades pertenecen respectivamente al Dominio Sudibérico (Subbético) y al Dominio de Alborán (Complejo de la Dorsal). Ambas unidades están constituidas por materiales mesozoicos y cenozoicos, aunque sus formaciones litoestratigráficas son de distinta naturaleza.Peer reviewe

Multicenter Performance Evaluation of MALDI-TOF MS for Rapid Detection of Carbapenemase Activity in Enterobacterales: The Future of Networking Data Analysis With Online Software

In this study, we evaluate the performance of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for rapid detection of carbapenemase activity in Enterobacterales in clinical microbiology laboratories during a multicenter networking validation study. The study was divided into three different stages: “software design,” “intercenter evaluation,” and “clinical validation.” First, a standardized procedure with an online software for data analysis was designed. Carbapenem resistance was detected by measuring imipenem hydrolysis and the results were automatically interpreted using the Clover MS data analysis software (Clover BioSoft, Spain). Second, a series of 74 genotypically characterized Enterobacterales (46 carbapenemase-producers and 28 non carbapenemase-producers) were analyzed in 8 international centers to ensure the reproducibility of the method. Finally, the methodology was evaluated independently in all centers during a 2-month period and results were compared with the reference standard for carbapenemase detection used in each center. The overall agreement rate relative to the reference method for carbapenemase resistance detection in clinical samples was 92.5%. The sensitivity was 93.9% and the specificity, 100%. Results were obtained within 60 min and accuracy ranged from 83.3 to 100% among the different centers. Further, our results demonstrate that MALDI-TOF MS is an outstanding tool for rapid detection of carbapenemase activity in Enterobacterales in clinical microbiology laboratories. The use of a simple in-house procedure with online software allows routine screening of carbapenemases in diagnostics, thereby facilitating early and appropriate antimicrobial therapy.Instituto de Salud Carlos III (ISCIII

Spatial preferences and behavioural patterns of lambs during fattening in straw enriched pens

The study analyses spatial preferences and behavioural patterns of lambs during fattening in straw enriched pens. Lambs were allocated in three replicates with 12 lambs each and housed in 6x6 m pens partially divided in two equal areas with and without straw bedding. Each pen was video-recorded continuously from 8 am to 8 pm on days 1, 5, 7, 14, 21 and 28. The use of different pen areas and the behaviour of the lambs were evaluated and analysed. The use of the space was significantly higher (p<0.05) for the straw area, where there was also more resting and affiliative interactions (p<0.05). In the areas without straw, animals walked more, remained standing longer periods (p<0.05) and had more stereotypic and aggressive behaviour (p<0.05). The study demonstrated that, when given the choice between two areas with similar resources, lambs prefer straw bedding. Straw is suggested to promote affiliation improving the adaptation to the feedlot. This could be useful to convince system managers that the availability of straw is beneficial to lamb welfare

Synthesis and reactivity of new silyl-substituted monocyclopentadienyl molybdenum and tungsten complexes

The functionalized silylated cyclopentadienyl molybdenum and tungsten complexes [MCpCl(CO)3H] (M=Mo, W; CpCl=η5-C5H4SiMe2Cl) are prepared easily from the reaction of [M(CO)3(NCMe)3] with C5H5SiMe2Cl in refluxing THF, via C–H activation and H transfer to the metal centre. Metathetical replacement of hydride by chloride is readily achieved when their methylene chloride solutions are treated with a few milliliters of CCl4 to give the chloro complexes [MCpCl(CO)3Cl] (M=Mo, W). The chloro–molybdenum complexes react with 1/2 equivalent of deoxygenated water to give the corresponding dinuclear complexes [{Mo(CO)3X}2(μ-CpOCp)], (X=H, Cl; CpOCp=η5-C5H4-SiMe2-O-SiMe2-η5-C5H4), whereas their reaction with one equivalent of anhydrous LiOH in toluene leads to selective substitution of the silicon-bonded chlorine atom to give the hydroxo complexes [MoCpOH(CO)3X] (X=H, Cl; CpOH=η5-C5H4SiMe2OH). These hydroxosilyl complexes can be transformed into the dinuclear compounds [{Mo(CO)3X}2(μ-CpOCp)] by heating (50°C, 2 h) or by their reaction with one equivalent of the respective hydrido and chloro derivatives [MoCpCl(CO)3X]. Total decarbonylation of the hydrido compounds results from oxidation with a stoichiometric amount of PCl5 to give the paramagnetic molybdenum(V) and tungsten(V) complexes [MCpClCl4] (M=Mo, W). Reactions of these complexes with one equivalent of NH2R in the presence of NEt3 yield the imido derivatives [MCpCl(NR)Cl2] (M=Mo, R=2,6-Me2-Ph; M=W, R=tBu) and subsequent oxidation of the tungsten complex with 1/2 equivalent of PCl5 gives [WCpCl(NtBu)Cl3]. Reduction of [MoCpClCl4] with two equivalents of Na/Hg gives the dinuclear molybdenum(III) complex [MoCpCl]2(μ-Cl)4. All of the reported compounds were characterized by elemental analysis and 1H- and 13C NMR-spectroscopy.The authors acknowledge DGICYT (project PB92-0178-C) for financial support

Reliability in perimetric multichannel contrast sensitivity measurements

Background: In this study, the reliability of perimetric contrast sensitivity measurements favouring the achromatic, the red-green and the blue-yellow post-receptorial mechanisms was analysed. Methods: A new technique, multichannel ATD perimetry, provides spatial and temporal stimuli favouring the detection by an achromatic mechanism (A), from a magno or parvocellular origin or by a red-green (RG) chromatic mechanism, with a parvocellular origin or a blue-yellow (BY) mechanism, with a koniocellular origin. The repeatability and reproducibility of contrast sensitivity measurements with these stimuli were studied in a group of 40 healthy subjects. The analysis was carried out on 21 testing points within a 60° by 40° fovea-centred region of the visual field. Results: The within-observer repeatability for the four mechanisms studied is either good or excellent when the intra-class correlation coefficient (ICC) can be calculated. For the remaining points, the Friedman's test finds that the measurements are repeatable. The between-observer reproducibility was either excellent or good in cases where the ICC was applied and according to the Friedman's test all results were reproducible. Conclusions: The results obtained showed good repeatability and reproducibility with A, RG and BY stimuli, although with BY stimuli repeatability is slightly worse. Future studies on the diagnostic validity of this device are based on the fact that changes of sensitivity can be compared by means of a visual single task, contrast sensitivity measurement and using a common metric.The ATD multichannel perimeter was built thanks to the support of the Spanish Ministerio de Ciencia y Tecnología Grants DPI2000-0116-P4-02 and PTR 1995-0909-OP, in collaboration with INDUSTRIAS DE OPTICA SA (San Cugat del Vallés, Spain)

Age-Mediated Transcriptomic Changes in Adult Mouse Substantia Nigra

Substantia nigra pars compacta (SNpc) is highly sensitive to normal aging and selectively degenerates in Parkinson's disease (PD). Until now, molecular mechanisms behind SNpc aging have not been fully investigated using high throughput techniques. Here, we show early signs of aging in SNpc, which are more evident than in ventral tegmental area (VTA), a region adjacent to SNpc but less affected in PD. Aging-associated early changes in transcriptome were investigated comparing late middle-aged (18 months old) to young (2 months old) mice in both SNpc and VTA. A meta-analysis of published microarray studies allowed us to generate a common >transcriptional signature> of the aged (≥ 24 months old) mouse brain. SNpc of late-middle aged mice shared characteristics with the transcriptional signature, suggesting an accelerated aging in SNpc. Age-dependent changes in gene expression specific to SNpc were also observed, which were related to neuronal functions and inflammation. Future studies could greatly help determine the contribution of these changes to SNpc aging. These data help understand the processes underlying SNpc aging and their potential contribution to age-related disorders like PD. © 2013 Gao et al.This work was funded by Spanish Ministry of Science and Education, Andalusian Government, and “Marcelino Botín” Foundation. “CIBERNED” (Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas) was funded by the Spanish “Carlos III” Institute of Health. LME was supported by the Spanish “Carlos III” Institute of Health. Support from the Spanish Ministry of Science and Education for MHF (“FPI” predoctoral fellowship) is also acknowledged.Peer Reviewe

Performance of sulfonated poly(vinyl alcohol)/graphene oxide polyelectrolytes for direct methanol fuel cells

"This is the peer reviewed version of the following article: [Performance of sulfonated poly(vinyl alcohol)/graphene oxide polyelectrolytes for direct methanol fuel cells], which has been published in final form at [10.1002/ente.202000124]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] The use nanotechnology along with the consideration of a functionalization and stabilization approach to the poly(vinyl alcohol) (PVA) was considered useful for the preparation of cost-effective polyelectrolyte membranes. A set of nanocomposite and crosslinked membranes based in PVA/SSA/GO were prepared and analyzed as polyelectrolytes in direct methanol fuel cells (DMFCs). The crosslinking and sulfonation by the use of sulfosuccinic acid (SSA) enhanced the stability and increased the proton conducting sites in the PVA structure. The presence of graphene oxide (GO) augmented the stability, remarkably decreased the methanol crossover and enhanced power density curves. An optimum value for proton conductivity was found for the 0.50%wt of GO proportion, which decreased to higher concentrations of GO. Given the power density curve dependency on both the proton conductivity and the crossover reduction, the performance of these membranes as polyelectrolytes in DMFCs is strictly related to the balance between both factors. Therefore, a proportion of GO of 0.75%wt may assure suitable proton conductivity 3 mS·cm-1 and high resistance to methanol permeability, reaching promising power density of 16 mW·cm-2 with lower hydration levels.The Spanish Ministry of Economy, Industry, and Competitiveness is acknowledged for the projects ENE2017-86711-C3-1-R, ENE2017-86711-C3-2-R, ENE2017-90932-REDT, and UPOV13-3E-1947. The Spanish Ministry of Education, Culture, and Sports is thanked for the predoctoral FPU grant for O. Gil-Castell (grant no. FPU13/01916).Gil-Castell, Ó.; Santiago, Ó.; Pascual-Jose, B.; Navarro, E.; Leo, TJ.; Ribes-Greus, MD. (2020). Performance of sulfonated poly(vinyl alcohol)/graphene oxide polyelectrolytes for direct methanol fuel cells. Energy Technology (Online). 8(7):1-10. https://doi.org/10.1002/ente.2020001241108