Influence of mismatch on the defects in relaxed epitaxial InGaAs/GaAs(100) films grown by molecular beam epitaxy

Thick (∼3 μm) films of InxGa1−xAs grown on GaAs(100) substrates, across the whole composition range, have been examined by transmission electron microscopy and double‐crystal x‐ray diffraction. The results were compared with the observed growth mode of the material determined by in situ reflection high‐energy electron diffraction in the molecular beam epitaxy growth system. The quality of the material degraded noticeably for compositions up to x∼0.5 associated with an increased density of dislocations and stacking faults. In contrast, improvements in quality as x approached 1.0 were correlated with the introduction of an increasingly more regular array of edge dislocations

Structural Influence of the Anode Materials towards Efficient Zn Deposition/Dissolution in Aqueous Zn-Iodide Flow Batteries

Zinc-iodide flow battery (ZIFB) is one of the best potential candidates for future grid-scale energy storage, due to its eye-catching features of benign, high energy density and non-corrosive nature. However major investigations have not done yet on the negative electrode of this battery where the Zn deposition/dissolution mechanism takes place, which may have an impact on the battery performance. Herein, we have reported a comparative study of different carbon-based anodes which are conventional graphite felt, carbon paper and graphite foil. Single-cell charge/discharge performances among these three different anodes depicts that the cell with planar, hydrophilic graphite foil anode is showing the best energy efficiency and the lowest cell resistance among the carbonaceous electrodes. Zinc dissolution process during discharge process seems to be the bottleneck for having a stable cell, which was corroborated by the use of a Zn foil anode that shows excellent efficiencies along the successive cycles

Influence of In and Ga additives onto SnO2 inkjet-printed semiconductor

Tin oxide is a multifunctional semiconductor that offers excellent capabilities in a variety of applications such as solar cells, catalysis and chemical sensors. In this work, tin-based semiconductors have been obtained by means of solution synthesis and inkjet, and compared to similar materials with In and Ga as additives. The effect of different thermal treatments after deposition is also studied. n-Type behavior with saturation mobility N2 cm2 /Vs has been observed, and suitability as a semiconductor for thin-film transistors (TFTs) demonstrated with on/off ratios of more than 8 decades. Both In and InGa additives are shown to provide superior environmental stability, as well as significant change from depletion to enhancement operation modes in TFTs

Nucleation and growth of GaN nanorods on Si (111) surfaces by plasma-assisted molecular beam epitaxy - The influence of Si- and Mg-doping

The self-assembled growth of GaN nanorods on Si (111) substrates by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions is investigated. An amorphous silicon nitride layer is formed in the initial stage of growth that prevents the formation of a GaN wetting layer. The nucleation time was found to be strongly influenced by the substrate temperature and was more than 30 min for the applied growth conditions. The observed tapering and reduced length of silicon-doped nanorods is explained by enhanced nucleation on nonpolar facets and proves Ga-adatom diffusion on nanorod sidewalls as one contribution to the axial growth. The presence of Mg leads to an increased radial growth rate with a simultaneous decrease of the nanorod length and reduces the nucleation time for high Mg concentrations

Suppressing water migration in aqueous Zn-iodide flow batteries by asymmetric electrolyte formulation

Zinc-iodide flow battery (ZIFB) is under research for the last years due to its suitability as a potential candidate for future electrochemical energy storage. During cycling, one of the biggest challenges that affect the reliable performance of ZIFB is the substantial water migration through the membrane because of differential molar concentrations between anolyte and catholyte that imbalance the osmotic pressures in each compartment. Considering the mass balances, herein we propose to equalize the total ionic concentration of electrolytes by the addition of extra solute into the compartment of lower ion concentration as a way to restrict the water crossover. Experimental validation of this electrolyte concentrations balancing strategy has been carried out by assessing the post-cycled electrolytes, and half-cell charged electrolytes, which confirms the efficient suppression of water migration from catholyte to anolyte. Besides, in-depth analysis of ions and water transport mechanism through Nafion 117 membrane confirms that solvated K+ ions of lower ionic radius compared to solvated Zn2+ ions, are the dominant migrating carrier. Therefore, the addition of extra KI solute is beneficial to suppress the major transport of large hydrated Zn2+ ions along with the higher amount of water. Finally, the improved ZIFB cell behaviour with enhanced electrical conductivity, discharge capacity, and voltage efficiency in the cell assembled with the electrolytes of balanced molar concentrations concludes our present study, proving that tuning the electrolytes concentrations is an effective way to suppress water migration as an appealing method in the prospect of upscaling ZIFB application

Uso de los antihistamínicos en patología alérgica

Antihistamínic; Al·lèrgia; Urticària; Rinitis; Efectes adversos; InteraccionsAntihistamínico; Alergia; Urticaria; Rinitis; Efectos adversos; InteraccionesAntihistamine; Allergy; Urticaria; Rhinitis; Adverse effects; InteractionsEls antihistamínics anti-H1 són els fàrmacs més emprats per al tractament de les malalties al·lèrgiques. Es classifiquen en antihistamínics de primera generació (clorfeniramina, difenhidramina, hidroxizina) i de segona generació (bilastina, cetirizina, desloratadina, ebastina, fexofenadina, levocetirizina, loratadina, rupatadina). Actualment, per via oral, es recomana utilitzar sempre antihistamínics de segona generació amb una acció més selectiva sobre els receptors H1 i una baixa liposolubilitat que permet una distribució limitada al sistema nerviós central (SNC). En cas de necessitar un antihistamínic parenteral només es disposa de la dexclorfeniramina, que és de primera generació. Els antihistamínics són efectius en el tractament de les rinoconjuntivitis al·lèrgiques i les urticàries de qualsevol etiologia. L’elevada prevalença de la rinitis en la població general (20%) fa que la prescripció d’antihistamínics sigui molt elevada. En la rinitis són més efectius per tractar la mucositat, la pruïja i els esternuts que la congestió nasal. També s’utilitzen com a tractament de la urticària crònica espontània. Així mateix, els antihistamínics no controlen la pruïja de la dermatitis atòpica ni són el tractament de primera línia en l’anafilaxi. Els antihistamínics anti-H1 són, en general, fàrmacs ben tolerats. Els de primera generació creuen la barrera hematoencefàlica i poden produir sedació i efectes anticolinèrgics centrals (confusió, agitació, etc.) i perifèrics (retenció d’orina, sequedat de boca, xerostomia). En el cas que un pacient necessiti tractament antihistamínic és important tenir en compte la càrrega anticolinèrgica dels fàrmacs que està prenent; això resulta especialment rellevant en pacients d’edat avançada. Un altre efecte advers d’alguns antihistamínics, potencialment greu, és la prolongació de l’interval QT, que va motivar la retirada del mercat de fàrmacs com astemizole i terfenadina. Cal tenir present que hi ha certs grups de població (embarassades, lactants, edat avançada, insuficiència renal i/o hepàtica i nens i nenes) en els quals els antihistamínics s’han de prescriure amb precaució tenint en compte les recomanacions de la fitxa tècnica del fàrmac. En aquest Butlletí es revisen els antihistamínics disponibles per a les principals malalties al·lèrgiques al nostre entorn.Los antihistamínicos antiH1 son los fármacos más utilizados para el tratamiento de las enfermedades alérgicas. Se clasifican en antihistamínicos de primera generación (clorfeniramina, difenhidramina, hidroxicina) y de segunda generación (bilastina, cetirizina, desloratadina, ebastina, fexofenadina, levocetirizina, loratadina, rupatadina). Actualmente, por vía oral, se recomienda utilizar siempre antihistamínicos de segunda generación con una acción más selectiva sobre los receptores H1 y una baja liposolubilidad que permite una distribución limitada en el sistema nervioso central (SNC). En caso de precisar un antihistamínico parenteral solo se dispone de la dexclorfeniramina, que es de primera generación. Los antihistamínicos son efectivos en el tratamiento de las rinoconjuntivitis alérgicas y las urticarias de cualquier etiología. La elevada prevalencia de la rinitis en la población general (20%) hace que la prescripción de antihistamínicos sea muy elevada. En la rinitis son más efectivos para tratar la mucosidad, el prurito y los estornudos de la congestión nasal. También se utilizan como tratamiento de la urticaria crónica espontánea. Aun así, los antihistamínicos no controlan el prurito de la dermatitis atópica ni son el tratamiento de primera línea en la anafilaxis. Los antihistamínicos antiH1 son, en general, fármacos bien tolerados. Los de primera generación cruzan la barrera hematoencefálica y pueden producir sedación y efectos anticolinérgicos, centrales (confusión, agitación, etc.…) y periféricos (retención de orina, sequedad de boca, xerostomía). En el caso en el que un paciente precise tratamiento antihistamínico es importante tener en cuenta la carga anticolinérgica de los fármacos que está tomando; esto resulta especialmente relevante en pacientes de edad avanzada. Otro efecto adverso, potencialmente grave, de algunos antihistamínicos es la prolongación del intervalo QT, que motivó la retirada del mercado de fármacos como astemizol y terfenadina. Se ha de tener presente que hay ciertos grupos de población (embarazadas, mujeres en periodo de lactancia, edad avanzada, insuficiencia renal y/o hepática y niños) en los que los antihistamínicos se deben prescribir con precaución teniendo en cuenta las recomendaciones de la ficha técnica del fármaco. En este boletín se revisan los antihistamínicos disponibles para las principales enfermedades alérgicas de nuestro entorno

Electrical properties of individual tin oxide nanowires contacted to platinum electrodes

A simple and useful experimental alternative to field-effect transistors for measuring electrical properties free electron concentration nd, electrical mobility , and conductivity in individual nanowires has been developed. A combined model involving thermionic emission and tunneling through interface states is proposed to describe the electrical conduction through the platinum-nanowire contacts, fabricated by focused ion beam techniques. Current-voltage I-V plots of single nanowires measured in both two- and four-probe configurations revealed high contact resistances and rectifying characteristics. The observed electrical behavior was modeled using an equivalent circuit constituted by a resistance placed between two back-to-back Schottky barriers, arising from the metal-semiconductor-metal M-S-M junctions. Temperature-dependent I-V measurements revealed effective Schottky barrier heights up to BE= 0.4 eV

Adaptation of Cu(In, Ga)Se2 photovoltaics for full unbiased photocharge of integrated solar vanadium redox flow batteries

The integration of photovoltaics and vanadium redox flow batteries (VRFB) is a promising alternative for the direct conversion and storage of solar energy in a single device, considering their inherent higher energy density versus other redox pairs. However, this integration is not seamless unless the photovoltaic system is customized to the voltage needs of the battery, which unlike artificial photosynthesis, continuously increase with the state-of-charge. We have developed integrated solar VRFB with adapted low-cost Cu(In, Ga)Se2 modules of 3 and 4 series-connected cells (solar efficiency of mini-solar module 8.1%), and considering the voltage requirements (1.3-1.6V), we have evaluated the influence of the photovoltaic operation region on the final efficiency of the solar VRFB. Full unbiased photocharge under 1 Sun illumination has been achieved reaching high energy (77%), solar-to-charge (7.5%) and overall round trip energy conversion efficiencies (5.0%) excelling the values reported in literature for other solar VRFB, thus demonstrating the feasibility and intrinsic potential of adapting low-cost commercial photovoltaics to such energy storage systems.Peer ReviewedPostprint (author's final draft

Síntesis de capas de SiC en substrato de Si mediante implantación iónica

En este trabajo se investiga la síntesis de estructuras SiC/Si mediante implantación iónica de carbono en Si. Las implantaciones se han realizado a energías entre 25 y 300 keV y las dosis en el rango lO^^ylO^^ cm , manteniendo el substrato a temperatura ambiente o 500°C. Algunas estructuras han sido recocidas a 1150°C. Los resultados indican que implantando a temperatura ambiente se forma una capa de SiC amorfa y de composición gradual, que recristaliza formando precipitados de ß-SiC con orientaciones aleatorias después del recocido. Además se forma un capa superficial rica en carbono, debida a la difusión del carbono hacia la superficie durante la implantación, y que desaparece con el recocido. Implantando a 500°C se forma directamente una capa con una muy alta densidad de precipitados de ß-SiC orientados preferencialmente con la matriz de silicio. Dada la estabilidad térmica y química de dicha capa se han realizado membranas de SiC mediante técnicas fotolitográficas y ataque químico selectivo, cuya rugosidad superficial es inferior a 6 nm. Estas membranas muestran unos gradientes de tensiones residuales, que prácticamente desaparecen después del recocido. Los resultados confirman la potencialidad de la implantación iónica para la formación de estructuras microme-cánicas de SiC sobre Si