11 research outputs found

    Effect of the AlAs capping layer thickness on the structure of InAs/GaAs QD

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    Recently, very thin AlAs capping layers (CLs) have been proposed as a useful tool to increase the performance of InAs/GaAs quantum dot (QDs) devices. However, the structure of QDs after AlAs deposition remains poorly understood and the mechanisms to explain it are often contradictory. In this work, the structural and compositional changes of InAs QDs using different AlAs CL thicknesses have been studied by state-of-the-art STEM-related techniques. First, the heights and In contents of InAs QDs progressively increase with the CL thickness, demonstrating that the AlAs capping produces a strong shielding effect against the decomposition of QDs. However, QD populations for CL thicknesses above 5 ML split into a bimodal distribution in which smaller lenticular QDs cohabit with bigger truncated pyramids. Second, the actual Al contents around the QDs are well below the nominal design, but increasing for thicker CLs. Its distribution is initially non-uniform, tending to accumulate on the flanks of the QDs to the detriment of the apex. Only for thicknesses above 2 ML the Al contents around the QDs start to be similar to those in the regions between the QDs, behaving as a continuous film without irregularities from 5 ML onwards. © 2021 The Author(s)The work has been co-financed by the Spanish National Research Agency (AEI projects MAT2016-77491-C2-2-R and PID2019-106088RB-C33), Regional Government of Andalusia (project FEDER-UCA18-108319) and the European Regional Development Fund (ERDF)

    Growth interruption strategies for interface optimization in GaAsSb/GaAsN type-II superlattices

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    Recently, GaAsSb/GaAsN type II short-period superlattices (SLs) have been proposed as suitable structures to be implemented in the optimal design of monolithic multi-junction solar cells. However, due to strong surface Sb segregation, experimental Sb composition profiles differ greatly from the nominal square-wave design. In this work, the improvement of the interface quality of these SLs in terms of compositional abruptness and surface roughness has been evaluated by implementing different growth interruption times under Sb4/As4 (soaking) and As4 (desorption) overpressure conditions before and after the growth of GaAsSb layers, respectively. The com-bined effects of both processes enhance Sb distribution, achieving squarer compositional profiles with reduced surface roughness interfaces. It has been found that the improvement in compositional abruptness is quantita-tively much higher at the lower interface, during soaking, than at the upper interface during desorption. Conversely, a larger decrease in surface roughness is achieved at the upper interface than at the lower interface. Fitting of the Sb segregation profiles using the 3-layer kinetic fluid model has shown that the increase in Sb incorporation rate is due to the decrease in segregation energy, presumably to changes in the surface recon-struction of the floating layer at the surface

    Suppressing the Effect of the Wetting Layer through AlAs Capping in InAs/GaAs QD Structures for Solar Cells Applications

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    Recently, thin AlAs capping layers (CLs) on InAs quantum dot solar cells (QDSCs) have been shown to yield better photovoltaic efficiency compared to traditional QDSCs. Although it has been proposed that this improvement is due to the suppression of the capture of photogenerated carriers through the wetting layer (WL) states by a de-wetting process, the mechanisms that operate during this process are not clear. In this work, a structural analysis of the WL characteristics in the AlAs/InAs QD system with different CL-thickness has been made by scanning transmission electron microscopy techniques. First, an exponential decline of the amount of InAs in the WL with the CL thickness increase has been found, far from a complete elimination of the WL. Instead, this reduction is linked to a higher shield effect against QD decomposition. Second, there is no compositional separation between the WL and CL, but rather single layer with a variable content of InAlGaAs. Both effects, the high intermixing and WL reduction cause a drastic change in electronic levels, with the CL making up of 1-2 monolayers being the most effective configuration to reduce the radiative-recombination and minimize the potential barriers for carrier transport.The work has been co-financed by the Spanish National Research Agency (AEI projects MAT2016-77491-C2-2-R and PID2019-106088RB-C33), Regional Government of Andalusia (project FEDER-UCA18-108319) and the European Regional Development Fund (ERDF)

    Tailoring of AlAs/InAs/GaAs QDs Nanostructures via Capping Growth Rate

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    The use of thin AlA capping layers (CLs) on InAs quantum dots (QDs) has recently received considerable attention due to improved photovoltaic performance in QD solar cells. However, there is little data on the structural changes that occur during capping and their relation to different growth conditions. In this work, we studied the effect of AlA capping growth rate (CGR) on the structural features of InAs QDs in terms of shape, size, density, and average content. As will be shown, there are notable differences in the characteristics of the QDs upon changing CGR. The Al distribution analysis in the CL around the QDs was revealed to be the key. On the one hand, for the lowest CGR, Al has a homogeneous distribution over the entire surface, but there is a large thickening of the CL on the sides of the QD. As a result, the QDs are lower, lenticular in shape, but richer in In. On the other hand, for the higher CGRs, Al accumulates preferentially around the QD but with a more uniform thickness, resulting in taller QDs, which progressively adopt a truncated pyramidal shape. Surprisingly, intermediate CGRs do not improve either of these behaviors, resulting in less enriched QDs

    Genetic landscape of 6089 inherited retinal dystrophies affected cases in Spain and their therapeutic and extended epidemiological implications

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    Inherited retinal diseases (IRDs), defined by dysfunction or progressive loss of photoreceptors, are disorders characterized by elevated heterogeneity, both at the clinical and genetic levels. Our main goal was to address the genetic landscape of IRD in the largest cohort of Spanish patients reported to date. A retrospective hospital-based cross-sectional study was carried out on 6089 IRD affected individuals (from 4403 unrelated families), referred for genetic testing from all the Spanish autonomous communities. Clinical, demographic and familiar data were collected from each patient, including family pedigree, age of appearance of visual symptoms, presence of any systemic findings and geographical origin. Genetic studies were performed to the 3951 families with available DNA using different molecular techniques. Overall, 53.2% (2100/3951) of the studied families were genetically characterized, and 1549 different likely causative variants in 142 genes were identified. The most common phenotype encountered is retinitis pigmentosa (RP) (55.6% of families, 2447/4403). The most recurrently mutated genes were PRPH2, ABCA4 and RS1 in autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL) NON-RP cases, respectively; RHO, USH2A and RPGR in AD, AR and XL for non-syndromic RP; and USH2A and MYO7A in syndromic IRD. Pathogenic variants c.3386G > T (p.Arg1129Leu) in ABCA4 and c.2276G > T (p.Cys759Phe) in USH2A were the most frequent variants identified. Our study provides the general landscape for IRD in Spain, reporting the largest cohort ever presented. Our results have important implications for genetic diagnosis, counselling and new therapeutic strategies to both the Spanish population and other related populations.This work was supported by the Instituto de Salud Carlos III (ISCIII) of the Spanish Ministry of Health (FIS; PI16/00425 and PI19/00321), Centro de Investigaci√≥n Biom√©dica en Red Enfermedades Raras (CIBERER, 06/07/0036), IIS-FJD BioBank (PT13/0010/0012), Comunidad de Madrid (CAM, RAREGenomics Project, B2017/BMD-3721), European Regional Development Fund (FEDER), the Organizaci√≥n Nacional de Ciegos Espa√Īoles (ONCE), Fundaci√≥n Ram√≥n Areces, Fundaci√≥n Conchita R√°bago and the University Chair UAM-IIS-FJD of Genomic Medicine. Irene Perea-Romero is supported by a PhD fellowship from the predoctoral Program from ISCIII (FI17/00192). Ionut F. Iancu is supported by a grant from the Comunidad de Madrid (CAM, PEJ-2017-AI/BMD7256). Marta del Pozo-Valero is supported by a PhD grant from the Fundaci√≥n Conchita R√°bago. Berta Almoguera is supported by a Juan Rodes program from ISCIII (JR17/00020). Pablo Minguez is supported by a Miguel Servet program from ISCIII (CP16/00116). Marta Corton is supported by a Miguel Servet program from ISCIII (CPII17/00006). The funders played no role in study design, data collection, data analysis, manuscript preparation and/or publication decisions

    Supplementary Material for: Cost of Hospitalizations due to Exacerbation in Patients with Non-Cystic Fibrosis Bronchiectasis

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    <b><i>Background:</i></b> Knowing the cost of hospitalizations for exacerbation in bronchiectasis patients is essential to perform cost-effectiveness studies of treatments that aim to reduce exacerbations in these patients. <b><i>Objectives:</i></b> To find out the mean cost of hospitalizations due to exacerbations in bronchiectasis patients, and to identify factors associated with higher costs. <b><i>Methods:</i></b> Prospective, observational, multicenter study in adult bronchiectasis patients hospitalized due to exacerbation. All expenses from the patients’ arrival at hospital to their discharge were calculated: diagnostic tests, treatments, transferals, home hospitalization, admission to convalescence centers, and hospitals’ structural costs for each patient (each hospital’s tariff for emergencies and 70% of the price of a bed for each day in a hospital ward). <b><i>Results:</i></b> A total of 222 patients (52.7% men, mean age 71.8 years) admitted to 29 hospitals were included. Adding together all the expenses, the mean cost of the hospitalization was EUR 5,284.7, most of which correspond to the hospital ward (86.9%), and particularly to the hospitals’ structural costs. The adjusted multivariate analysis showed that chronic bronchial infection by <i>Pseudomonas aeruginosa</i>, days spent in the hospital, and completing the treatment with home hospitalization were factors independently associated with a higher overall cost of the hospitalization. <b><i>Conclusions:</i></b> The mean cost of a hospitalization due to bronchiectasis exacerbation obtained from the individual data of each episode is higher than the cost per process calculated by the health authorities. The most determining factor of a higher cost is chronic bronchial infection due to <i>P. aeruginosa</i>, which leads to a longer hospital stay and the use of home hospitalization

    Genetic landscape of 6089 inherited retinal dystrophies affected cases in Spain and their therapeutic and extended epidemiological implications

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    Inherited retinal diseases (IRDs), defined by dysfunction or progressive loss of photoreceptors, are disorders characterized by elevated heterogeneity, both at the clinical and genetic levels. Our main goal was to address the genetic landscape of IRD in the largest cohort of Spanish patients reported to date. A retrospective hospital-based cross-sectional study was carried out on 6089 IRD affected individuals (from 4403 unrelated families), referred for genetic testing from all the Spanish autonomous communities. Clinical, demographic and familiar data were collected from each patient, including family pedigree, age of appearance of visual symptoms, presence of any systemic findings and geographical origin. Genetic studies were performed to the 3951 families with available DNA using different molecular techniques. Overall, 53.2% (2100/3951) of the studied families were genetically characterized, and 1549 different likely causative variants in 142 genes were identified. The most common phenotype encountered is retinitis pigmentosa (RP) (55.6% of families, 2447/4403). The most recurrently mutated genes were PRPH2, ABCA4 and RS1 in autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL) NON-RP cases, respectively; RHO, USH2A and RPGR in AD, AR and XL for non-syndromic RP; and USH2A and MYO7A in syndromic IRD. Pathogenic variants c.3386G > T (p.Arg1129Leu) in ABCA4 and c.2276G > T (p.Cys759Phe) in USH2A were the most frequent variants identified. Our study provides the general landscape for IRD in Spain, reporting the largest cohort ever presented. Our results have important implications for genetic diagnosis, counselling and new therapeutic strategies to both the Spanish population and other related populations

    Genetic landscape of 6089 inherited retinal dystrophies affected cases in Spain and their therapeutic and extended epidemiological implications

    No full text
    Inherited retinal diseases (IRDs), defined by dysfunction or progressive loss of photoreceptors, are disorders characterized by elevated heterogeneity, both at the clinical and genetic levels. Our main goal was to address the genetic landscape of IRD in the largest cohort of Spanish patients reported to date. A retrospective hospital-based cross-sectional study was carried out on 6089 IRD affected individuals (from 4403 unrelated families), referred for genetic testing from all the Spanish autonomous communities. Clinical, demographic and familiar data were collected from each patient, including family pedigree, age of appearance of visual symptoms, presence of any systemic findings and geographical origin. Genetic studies were performed to the 3951 families with available DNA using different molecular techniques. Overall, 53.2% (2100/3951) of the studied families were genetically characterized, and 1549 different likely causative variants in 142 genes were identified. The most common phenotype encountered is retinitis pigmentosa (RP) (55.6% of families, 2447/4403). The most recurrently mutated genes were PRPH2, ABCA4 and RS1 in autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL) NON-RP cases, respectively; RHO, USH2A and RPGR in AD, AR and XL for non-syndromic RP; and USH2A and MYO7A in syndromic IRD. Pathogenic variants c.3386G &gt; T (p.Arg1129Leu) in ABCA4 and c.2276G &gt; T (p.Cys759Phe) in USH2A were the most frequent variants identified. Our study provides the general landscape for IRD in Spain, reporting the largest cohort ever presented. Our results have important implications for genetic diagnosis, counselling and new therapeutic strategies to both the Spanish population and other related populations

    [Correspondencia de Camilo D√≠az Bali√Īo] , 1917-1936

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    Mss. (alg√ļns en fotocopia) aut√≥grafo e mecanografiadoResumen: Correspondencia recibida por Camilo D√≠az Bali√Īo entre os anos 1917-1936 relacionada con asuntos persoais e laboraisBiblioteca de GaliciaForma de ingreso: Dep√≥sito. Fuente de ingreso: D√≠az Pardo, Isaac. Fecha de ingreso: 2011. Propietario: Herdeiros de Isaac D√≠az PardoDixitalizaci√≥n Telef√≥nica-IDP 2012Cont√©n : Cartas de: Manuel Abelenda (1 p√°x.) -- Cesar Alvarez (1 p√°x.) -- Carlos Amigo Coll√≠a (2 p√°xs.) -- Banco Hispano-Americano (2 p√°xs.) -- Alfonso Barreiro (3 p√°xs.) -- Eliseo Barros Gamallo (1 p√°x.),(2 p√°xs.) -- Ram√≥n Beade (2 p√°xs.) -- Benito(2 p√°xs.) -- Fernando Blanco(1 p√°x.) -- Jos√© Bouzas y Cardama (1 p√°x.) -- Albino Bouz√≥ Fern√°ndez (1 p√°x.),(2 p√°xs) -- Jos√© Cabada V√°zquez (4 p√°xs.),(1 p√°x.),(1 p√°x.) --Salvador Cabeza (1 p√°x.) -- Antonio Carballa (1 p√°x.) -- Leandro y Euxenio Carr√© (2 p√°xs.) -- V. Carro (1 p√°x.) -- Santiago Casares (1 p√°x.) -- Alvaro Cebreiro (2 p√°xs.) -- Centro Gallego de Buenos Aires (1 p√°x.),(1 p√°x.) -- Compostela (2 p√°xs.) -- Manolo: Continental (2 p√°xs.) -- Coral de Ruada (1 p√°x.),(2 p√°xs.) -- Amando Cotarelo(1 p√°x.),(1 p√°x.) -- Eduardo Dorado Xaneiro (8 p√°x.) -- C√≠rculo Mercantil e Idustrial: Ram√≥n Fern√°ndez (1 p√°x.) --Virgilio Fern√°ndez(3 p√°xs.) -- Ram√≥n Fern√°ndez Mato (2 p√°xs.) -- B. Ferreiro(1 p√°x.) -- Jenaro de la Fuente (1 p√°x.) -- Isaac Fraga: Esp√©ctaculos Empresa Fraga (1 p√°x.),(1 p√°x.) -- Antonio Folgar Lema(1 p√°x.)--Alicio Garcitoral (1 p√°x.) -- C√°ndido Gonz√°lez Ra√Īo (1 p√°x.) -- Daniel Gonz√°lez Rodriguez (2 p√°xs.),(2 p√°xs.) -- Edurardo G.del R√≠o (1 p√°x.) -- Hermanos Hern√°ndez (2 p√°xs.),(1 p√°x.),(1 p√°x.),(1 p√°x.) -- Jos√© Iglesias S√°nchez (2 p√°xs.) -- Irmandades da Fala (1 p√°x.) -- Jos√© Silva? (2 p√°xs.) -- Arturo Longa (1 p√°x.) -- Casimiro L√≥pez (1 p√°x.) -- Edmundo L√≥pez (1 p√°x.),(1 p√°x.) -- Eduardo R. Losada y Rebell√≥n (2 p√°x.) -- Carlos Maside (1 p√°x.) -- Enrique Mayer (1 p√°x.) -- Antonio M√©ndez Laserna (1 p√°x.) -- Anselmo Pad√≠n (1 p√°x.) -- Xavier Pardo (1 p√°x.) -- Partido Republicano Radical Socialista (1 p√°x.) -- P√©rez Bustamante (1 p√°x.) -- Modesto Pi√Īeiro (2 p√°xs.) -- Salustiano Portela (2 p√°xs.) -- Jos√© Seijo Rubio (2 p√°xs.) -- Suarez Picallo (2 p√°xs.) -- Luis Losada (1 p√°x), (1 p√°x.) -- Ricardo Vald√©s (2 p√°xs.),(2 p√°xs.),(2 p√°xs.),(1 p√°x.) -- A.Nilo Varela (1 p√°x.),(2 p√°xs.),(2 p√°xs.) -- Juan Varela de Limia (1 p√°x.) -- Victorino? Varela (1 p√°x.) -- Jes√ļs Varela (3 p√°xs.) -- F.V√°zquez Suarez (1 p√°x.) -- Santiago Vidal Gimeno (1 p√°x.) -- Pedro Vieitez (1 p√°x.) -- M. Villar (2 p√°xs.) -- An√≥nima (1 p√°x.) -- An√≥nima (1 p√°x.
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