Influence of metal organic chemical vapour deposition growth conditions on vibrational and luminescent properties of ZnO nanorods

Producción CientíficaA detailed optical characterization by means of micro Raman and cathodoluminescence spectroscopy of catalyst-free ZnO nanorods grown by atmospheric-metal organic chemical vapour deposition has been carried out. This characterization has allowed correlating the growth conditions, in particular the precursors partial-pressures and growth time, with the optical properties of nanorods. It has been shown that a high Zn supersaturation can favor the incorporation of nonradiative recombination centers, which can tentatively be associated with ZnI-related defects. Characterization of individual nanorods has evidenced that ZnI-related defects have a tendency to accumulate in the tip part of the nanorods, which present dark cathodoluminescence contrast with respect to the nanorods bottom. The effect of a ZnO buffer layer on the properties of the nanorods has been also investigated, showing that the buffer layer improves the luminescence efficiency of the ZnO nanorods, revealing a significant reduction of the concentration of nonradiative recombination centers.Ministerio de Ciencia e Innovación (Projects MAT2007-66129, MAT-2010-20441-C02, MAT-2010-16116, and TEC2011-28076-C02-02)Generalitat Valenciana (Prometeo/2011-035 and ISIC/2012/008, Institute of Nanotechnologies for Clean Energies

Thermal Conduction in Systems out of Hydrostatic Equilibrium

We analyse the effects of thermal conduction in a relativistic fluid, just after its departure from hydrostatic equilibrium, on a time scale of the order of thermal relaxation time. It is obtained that the resulting evolution will critically depend on a parameter defined in terms of thermodynamic variables, which is constrained by causality requirements.Comment: 16 pages, emTex (LaTex 2.09). To appear in Classical and Quantum Gravit

Rules, Standards, and the Internal Point of View

Large scale structure and cosmolog

Effects of ammonium nitrate, cesium chloride and tetraethylammonium on high-affinity potassium uptake in habanero pepper plantlets (Capsicum chinense Jacq.)

Potassium (K+) is an essential nutrient and the most abundant cation in plant cells. Plants have a wide variety of transport systems for K+ acquisition that catalyze K+ uptake across a wide spectrum of external K+ concentrations and mediate K+ movement within the plant, as well as its release into the environment. The KUP/HAK/KT transporter family plays a key role in K+ homeostasis in plant cells. The present study demonstrates that habanero pepper plantlets have a clear pattern of K+ uptake when resupplemented with K+ after K+ starvation. Habanero pepper plantlets, re-supplemented with a solution containing low concentrations of K+ after 72, 96 or 120 h of K+ starvation were able to decrease the amount of K+ in the solution at different time points. To study the effect of NH4+, we added different concentrations of NH4NO3 to the medium solution and demonstrated that NH4+ inhibited K+ uptake in a dose-dependent manner. When the plantlets were subjected to K+ starvation for 72 h and then resupplemented with 50 or 100 μM K+, exposure to K+ channel blockers (10 mM CsCl and 20 mM TEA) decreased their K+ uptake compared with the control treatment. A model demonstrating the process of K+ uptake through an NH4+-insensitive component was proposed.Key words: Potassium, high affinity transporters, channel blockers, ammonium

Dissipative fluids out of hydrostatic equilibrium

In the context of the M\"{u}ller-Israel-Stewart second order phenomenological theory for dissipative fluids, we analyze the effects of thermal conduction and viscosity in a relativistic fluid, just after its departure from hydrostatic equilibrium, on a time scale of the order of relaxation times. Stability and causality conditions are contrasted with conditions for which the ''effective inertial mass'' vanishes.Comment: 21 pages, 1 postscript figure (LaTex 2.09 and epsfig.sty required) Submitted to Classical and Quantum Gravit

Improved Performance of an Epoxy Matrix as a Result of Combining Graphene Oxide and Reduced Graphene

We present an easy and effective way to improve the mechanical properties of an epoxy matrix by reinforcing it with a combination of graphene oxide (GO) and reduced graphene oxide (RGO). These nanocomposites were prepared with different load of nanofillers: 0.1, 0.4, 0.7, 1.0 wt% and a neat epoxy. Ratios of graphene oxide and reduced graphene (GO : RGO) employed were: 0 : 1, 0.25 : 0.75, 0.5 : 0.5, 0.75 : 0.25, and 1 : 0. Results show that with only 0.4 wt% and a ratio 0.2 : 0.75 of GO : RGO, tensile strength and tensile toughness are 52% and 152% higher than neat epoxy while modulus of elasticity was improved ~20%. The obtained results suggest that it is possible achieve advantageous properties by combining graphene in oxidized and reduced conditions as it shows a synergic effect by the presence of both nanofillers

Evolución de las capacidades físicas en jugadores jóvenes de baloncesto de medio nivel

El objetivo de estudio fue analizar la evolución de las capacidades físicas de jugadores de medio nivel a lo largo de 2 años (categoría: cadete y júnior). Metodo. 15 jugadores fueron evaluados durante 2 años: en el ultimo año de la etapa cadete (U16) y el primer año de la etapa junior (U18). Los tests fueron realizados en 4 momentos (M) de cada temporada [1.Septiembre (pre-temporada), 2. Diciembre, 3. Abril y 4. Julio, para un total de 8 pruebas]. La batería consistió en un test de 20 m sprint (MST), un test de agilidad T (AGIT), un lanzamiento de balón medicinal de 5 kg (5KGT), un salto (CMJ), un test Sit and Reach (SAR) y la Course Navette (CN). Resultados. Los principales resultados fueron:,los jugadores mejoraron en MST: [1º M: 3.16 ± 0.27 m/s Vs. 4º M: 2.87 ± 0.17 m/s; (p<0.05)]; en CMJ,observamos diferencias estadísticas entre el 1º y 8º M [1º M: 32.57 ± 2.8 cm Vs. 8º M: 42.14 ± 3.8 cm;(p<0.05)]; los resultados en SAR mostraron que los valores decrecieron (1º M: 13.14 ± 12.27 cm al 8º M: 6.42 ± 7.36 cm); finalmente, observamos diferencias significativas entre 1º M y el 8º M en CNT [1º M: 10.36 ± 1.7 paliers Vs. 8º M: 12.5 ± 1.4 paliers; (p<0.05)]. Conclusiones. Se constataron mejoras significativas en las capacidades neuromusculares, la potencia aeróbica y la flexibilidad

QUIJOTE scientific results - II. Polarisation measurements of the microwave emission in the Galactic molecular complexes W43 and W47 and supernova remnant W44

We present Q-U-I JOint TEnerife (QUIJOTE) intensity and polarisation maps at 10-20 GHz covering a region along the Galactic plane 24° ≳ l ≳ 45°, |b| ≳ 8°. These maps result from 210 h of data, have a sensitivity in polarisation of ≈ 40 μK beam and an angular resolution of ≈1°. Our intensity data are crucial to confirm the presence of anomalous microwave emission (AME) towards the two molecular complexesW43 (22σ) and W47 (8σ).We also detect at high significance (6σ) AME associated with W44, the first clear detection of this emission towards a supernova remnant. The new QUIJOTE polarisation data, in combination with Wilkinson Microwave Anisotropy Probe (WMAP), are essential to (i) determine the spectral index of the synchrotron emission in W44, β = -0.62 ± 0.03, in good agreement with the value inferred from the intensity spectrum once a free-free component is included in the fit; (ii) trace the change in the polarisation angle associated with Faraday rotation in the direction of W44 with rotation measure -404 ± 49 rad m and (iii) set upper limits on the polarisation ofW43 of Π < 0.39 per cent (95 per cent C.L.) from QUIJOTE 17 GHz, and < 0.22 per cent from WMAP 41 GHz data, which are the most stringent constraints ever obtained on the polarisation fraction of the AME. For typical physical conditions (grain temperature and magnetic field strengths), and in the case of perfect alignment between the grains and the magnetic field, the models of electric or magnetic dipole emissions predict higher polarisation fractions.This work has been partially funded by the Spanish Ministry of Economy and Competitiveness (MINECO) under the projects AYA2007-68058-C03-01, AYA2010-21766- C03-02, AYA2012-39475-C02-01, the Consolider-Ingenio project CSD2010-00064 (EPI: Exploring the Physics of Inflation) and also by the European Union’s Horizon 2020 research and innovation programme under grant agreement number 687312. FP thanks the European Commission under the Marie Sklodowska-Curie Actions within the H2020 program, Grant Agreement Number 658499-PolAME-H2020-MSCA-IF-2014.Peer Reviewe

Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar

Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4-6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tetheredballoon and meteorological tower-mounted sonic anemometer measurements made at spatial distances of a few hundred meters. Temporal lag analyses suggest that approximately half of the observed differences are due to spatial sampling considerations, such that the anticipated radar-based retrieval uncertainty is on the order of a factor of 2-3. Moreover, radar retrievals are clearly able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds