Combined photo- and electroreflectance of multijunction solar cells enabled by subcell electric coupling

Electric coupling between subcells of a monolithically grown multijunction solar cell in short circuit allows their simultaneous and independent characterization by means of photo- and electroreflectance. The photovoltage generated by selective absorption of the pump beam in a given subcell during photoreflectance measurements results in reverse biasing the complementary subunits at the modulation frequency set on the pump illumination. Such voltage bias modulation acts then as external perturbation on the complementary subcells. The spectral separation of the different subcell absorption ranges permits the probe beam to record in a single spectrum the response of the complete device as a combination of photo- and electroreflectance, thereby providing access for diagnosis of subcells on an individual basis. This form of modulation spectroscopy is demonstrated on a GaInP/GaAs tandem solar cell.Comment: 5 pages, 4 figures. This article has been accepted by Appl. Phys. Lett. After it is published, it will be found at https://doi.org/10.1063/1.506260

GaAs Nanowire pn-Junctions Produced by Low-Cost and High-Throughput Aerotaxy

Semiconductor nanowires could significantly boost the functionality and performance of future electronics, light-emitting diodes, and solar cells. However, realizing this potential requires growth methods that enable high-throughput and low-cost production of nanowires with controlled doping. Aerotaxy is an aerosol-based method with extremely high growth rate that does not require a growth substrate, allowing mass-production of high-quality nanowires at a low cost. So far, pn-junctions, a crucial element of solar cells and light-emitting diodes, have not been realized by Aerotaxy growth. Here we report a further development of the Aerotaxy method and demonstrate the growth of GaAs nanowire pn-junctions. Our Aerotaxy system uses an aerosol generator for producing the catalytic seed particles, together with a growth reactor with multiple consecutive chambers for growth of material with different dopants. We show that the produced nanowire pn-junctions have excellent diode characteristics with a rectification ratio of >105, an ideality factor around 2, and very promising photoresponse. Using electron beam induced current and hyperspectral cathodoluminescence, we determined the location of the pn-junction and show that the grown nanowires have high doping levels, as well as electrical properties and diffusion lengths comparable to nanowires grown using metal organic vapor phase epitaxy. Our findings demonstrate that high-quality GaAs nanowire pn-junctions can be produced using a low-cost technique suitable for mass-production, paving the way for industrial-scale production of nanowire-based solar cells

Analysis of the surface state of epi-ready Ge wafers

The surface state of Ge epi-ready wafers (such as those used on III-V multijunction solar cells) supplied by two different vendors has been studied using X-ray photoemission spectroscopy. Our experimental results show that the oxide layer on the wafer surface is formed by GeO and GeO2. This oxide layer thickness differs among wafers coming from different suppliers. Besides, several contaminants appear on the wafer surfaces, carbon and probably chlorine being common to every wafer, irrespective of its origin. Wafers from one of the vendors show the presence of carbonates at their surfaces. On such wafers, traces of potassium seem to be present too

A pilot 1-year follow-up randomised controlled trial comparing metacognitive training to psychoeducation in schizophrenia: effects on insight

Poor insight in schizophrenia spectrum disorders (SSD) is linked with negative outcomes. This single-centre, assessor-blind, parallel-group 1-year follow-up randomised controlled trial (RCT) tested whether metacognitive training (MCT) (compared to psychoeducation) may improve insight and outcomes in outpatients with SSD assessed: at baseline (T0); after treatment (T1) and at 1-year follow-up (T2). Insight (primary outcome) was measured with (i) the Schedule for Assessment of Insight-Expanded version- (SAI-E), including illness recognition (IR), symptom relabelling (SR), treatment compliance (TC) and total insight scores (TIS); and (ii) the Beck Cognitive Insight Scale (BCIS). Between-group comparisons were nonsignificant, while within the MCT group (but not within controls) there was a significant medium effect size for improved TIS at T2 (d = 0.67, P = 0.02). Secondary outcomes included cognitive measures: Jumping to Conclusions (JTC), Theory of Mind (ToM), plus symptom severity and functioning. Compared to psychoeducation, MCT improved the PANSS excitement (d = 1.21, P = 0.01) and depressed (d = 0.76, P = 0.05) factors at T2; and a JTC task both at T1 (P = 0.016) and at T2 (P = 0.031). Participants in this RCT receiving MCT showed improved insight at 1-year follow-up, which was associated with better mood and reduced JTC cognitive bias. In this pilot study, no significant benefits on insight of MCT over psychoeducation were detected, which may have been due to insufficient power

In-situ and Ex-situ characterization of III-V semiconductor materials and solar cells upon 10 MEV proton irradiation

In this work we present the results and analysis of a 10 MeV proton irradiation experiment performed on III-V semiconductor materials and solar cells. A set of representative devices including lattice-matched InGaP/GaInAs/Ge triple junction solar cells and single junction GaAs and InGaP component solar cells and a Ge diode were irradiated for different doses. The devices were studied in-situ before and after each exposure at dark and 1 sun AM0 illumination conditions, using a solar simulator connected to the irradiation chamber through a borosilicate glass window. Ex-situ characterization techniques included dark and 1 sun AM0 illumination I-V measurements. Furthermore, numerical simulation of the devices using D-AMPS-1D code together with calculations based on the TRIM software were performed in order to gain physical insight on the experimental results. The experiment also included the proton irradiation of an unprocessed Ge solar cell structure as well as the irradiation of a bare Ge(100) substrate. Ex-situ material characterization, after radioactive deactivation of the samples, includes Raman spectroscopy and spectral reflectivity

Males and females with first episode psychosis present distinct profiles of social cognition and metacognition

Altres ajuts: Royal Society of New Zealand - Marsden (E2987-3648) ; Obra Social La Caixa (RecerCaixa call 2013) ; Obra Social Sant Joan de Déu BML (RTI2018-100927-J-I00) ; Ministerio Regional de Salud AndaluzDeficits in social cognition and metacognition impact the course of psychosis. Sex diferences in social cognition and metacognition could explain heterogeneity in psychosis. 174 (58 females) patients with frst-episode psychosis completed a clinical, neuropsychological, social cognitive, and metacognitive assessment. Subsequent latent profle analysis split by sex yielded two clusters common to both sexes (a Homogeneous group, 53% and 79.3%, and an Indecisive group, 18.3% and 8.6% of males and females, respectively), a specifc male profle characterized by presenting jumping to conclusions (28.7%) and a specifc female profle characterized by cognitive biases (12.1%). Males and females in the homogeneous profle seem to have a more benign course of illness. Males with jumping to conclusions had more clinical symptoms and more neuropsychological defcits. Females with cognitive biases were younger and had lower self-esteem. These results suggest that males and females may beneft from specifc targeted treatment and highlights the need to consider sex when planning interventions

What seems to explain suicidality in Yucatan Mexican young adults? findings from an app-based mental health screening test using the SMART-SCREEN protocol

The relationship between suicidality, depression, anxiety, and well-being was explored in young adults (median age 20.7 years) from the State of Yucatan (Mexico), which has a suicide rate double that of other Mexican states. A cross-sectional study was carried out in 20 universities in Yucatan and 9,366 students were surveyed using validated questionnaires built into a smartphone app, applying partial least squares structural equation models. High suicide risk was assessed in 10.8% of the sample. Clinically relevant depression and anxiety levels were found in 6.6% and 10.5% of the sample, respectively, and 67.8% reported high well-being. Comparably higher levels of suicide risk, depression and anxiety, and lower well-being were found in women, who were also somewhat older than men in our study. Furthermore, path analysis in the structural equation model revealed that depression was the main predictor of suicidal behaviour as well as of higher anxiety levels and lower self-perceived well-being in the total sample and in both genders. Our findings draw attention to the association between suicidality, depression, anxiety, and well-being in Yucatan young adults and gender differences with this regard. Mental health screening via smartphone might be a useful tool to reach large populations and contribute to mental health policies, including regional suicide prevention effortsOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. No funding was received for this stud

Immunophenotypic characterization of plasma cells from monoclonal gammopathy of undetermined significance patients. Implications for the differential diagnosis between MGUS and multiple myeloma

Es el artículo seminal para distinguir entre célula plasmática normal y patológica en las gamm-patías monoclonales.[EN]Although the immunophenotype of plasma cells (PCs) from multiple myeloma (MM) patients has been extensively explored, information on the phenotypic characteristics of PCs in monoclonal gammopathy of undetermined significance (MGUS) patients is scanty and frequently controversial. Thus, the question of whether or not PCs are phenotypically different in the two disorders and whether this criteria could be useful for the differential diagnosis between MGUS and MM remains to be explored. In the present study, the immunophenotypic profile of bone marrow PCs (BMPCs) from a group of 76 MGUS patients has been analyzed by flow cytometry and compared with that of BMPCs present in both MM patients (n = 65) and control subjects (n = 10). For that purpose, a large panel of monoclonal antibodies against PC-related antigens was used together with a sensitive methodology in which a minimum of 10(3) PCs were studied. In all MGUS cases studied, two clearly defined and distinct PC subpopulations could be identified. One PC subpopulation, population A (33 +/- 31% of total PCs), constantly displayed a high CD38 expression with low forward light scatter (FSC)/side light scatter (SSC) and was positive for CD19 and negative for CD56 (only a small proportion of these PCs were weakly positive for CD56). The other PC subpopulation, population B (67 +/- 31% of total PCs), showed the opposite pattern; the antigen CD56 was strongly positive and CD19 was constantly negative, and it showed a lower CD38 expression and higher FSC/SSC values than population A. Clonality studies (cytoplasmic light chain restriction, DNA content studies, and polymerase chain reaction assessment) confirmed the clonal nature of PCs from population B and the polyclonal origin of PCs from population A. Moreover, the polyclonal PCs from MGUS displayed a phenotypic profile identical to that found in PCs from healthy individuals. By contrast, clonal PCs from all MGUS patients displayed a similar antigenic profile to myelomatous PCs, with clear phenotypic differences with respect to normal PCs: lower intensity of CD38 expression and a variable reactivity for markers that were not expressed in normal PCs, such as CD28, CD117, and sIg. Although the presence of residual polyclonal PCs was a constant finding in MGUS patients, it was a rare event in MM and, when present (only 22% of MM cases), its frequency was significantly lower than that observed in MGUS (0.25% versus 32.9%, respectively; P < 0.0001). Only 1.5% of patients with MM had more than 3% of normal PCs, whereas 98% of patients with MGUS had more than 3%. Moreover, as shown by multivariate analysis, the number of residual polyclonal PCs was the most powerful single parameter for the discrimination between MGUS and MM patients at diagnosis, even when only stage I MM cases were considered.Hospital Universitario de Salamanca Universidad de SalamancaHospital Universitario de Salamanc