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In the incipient world of functional industrial ceramics with photovoltaic applications, there is a need to reduce production costs while maximizing the systems’ useful life. The thin contact layers currently being manufactured are based on vacuum systems with high production costs and major problems of accelerated corrosion in photovoltaic applications. The electroless process produces very even and compact layers with very low costs through chelate-based chemicals. These layers have been formulated in this study with a view to obtaining appropriate electric characteristics for an optimum photoelectric performance in the assemblies. The morphological requirements are previously fitted through a glaze that acts as a barrier layer between the deposited coating and the porcelain tile, applied through tape casting. The characterisation of the metal layers obtained is started by SEM, an AFM and the Hall effect in order to determine the morphology and chemical characteristics required for these contact layers. The electric characterisation also allows their capacity for offering an optimum performance in the assemblies to be assessed. Finally, the performance of these layers with respect to corrosion is assessed in order to complete the assessment of their industrial suitability.En el incipiente mundo de las cerámicas industriales funcionales con aplicaciones fotovoltaicas existe la necesidad de reducir costes de producción al tiempo que se maximiza la vida útil de los sistemas. Las capas delgadas para contactos que se fabrican en la actualidad se basan en sistemas a vacio con altos costes de producción y una fuerte problemática de corrosión acelerada en aplicaciones fotovoltaicas. El proceso “libre de electrodos” (“electroless”) produce por vía química a partir de quelatos capas muy uniformes y compactas con costes muy reducidos. En el presente trabajo se formulan estas capas con vistas a conseguir características eléctricas adecuadas para un rendimiento fotoeléctrico óptimo en los dispositivos. Previamente se acoplan los requerimientos morfológicos mediante un esmalte que actúa como capa barrera entre la baldosa de porcelánico que se aplica por colage en cinta. La caracterización de las capas metálicas obtenidas, se inicia mediante SEM, AFM y efecto Hall para determinar la morfología y características químicas requeridas para estas capas de contacto. Adicionalmente la caracterización eléctrica permite evaluar su aptitud para ofrecer un rendimiento óptimo en los dispositivos. Finalmente, se evalúa el comportamiento frente a la corrosión de estas capas a fin de completar su evaluación de aptitud industrial.

Glasses of composition 50SiO2•30BaO•20ZnO, mol% (Zn1.5-50), 55SiO2•27BaO•18ZnO, mol% (Zn1.5-55), and 55SiO2•27BaO•18MgO, mol% (Mg1.5-55) present good properties for application in sealing planar solid oxide fuel cells with an intermediate temperature of operation (850ºC) (IT-SOFC). The sealing must take place on sintering the glass powder during the start-up of the cell between 700 and 850ºC. Further treatment at the operation temperature provokes the crystallisation of barium silicates with the subsequent increase of viscosity and seal rigidity. This work is a study of the sintering behaviour of these glasses using different heating rates and particle-size distributions of the glass powder in order to obtain dense and homogeneous seals. The glasses Zn1.5-55 and Mg1.5-55 with a particle size less than 63 μm heated at 2ºC/min reach final densities higher than 95%. A good agreement has been demonstrated between the measured sintering kinetics and those predicted with the sintering model of Clusters formation in the absence of concurrent crystallisation.Los vidrios de composición molar 50SiO2•30BaO•20ZnO (Zn1.5-50), 55SiO2•27BaO•18ZnO (Zn1.5-55), y 55SiO2•27BaO•18MgO (Mg1.5-55) presentan buenas propiedades para su aplicación en el sellado de pilas de combustible de óxido sólido de configuración plana y temperatura de operación intermedia (850ºC) (IT-SOFC). El sellado debe producirse a través de la sinterización del polvo de vidrio, durante el arranque de la pila, a temperaturas entre 700 y 850ºC. El tratamiento posterior a la temperatura de operación da lugar a la cristalización de silicatos de bario con el consiguiente aumento de viscosidad y rigidez del sello. Este trabajo es un estudio del comportamiento de sinterización de estos vidrios utilizando diferentes velocidades de calentamiento y distribuciones de tamaño de partícula del polvo de vidrio, para la obtención final de sellos densos y homogéneos. Los vidrios Zn1.5-55 y Mg1.5-55 con un tamaño de partícula menor que 63 μm y tratados a 2ºC/min alcanzan densidades finales superiores al 95%. Por otra parte, se ha demostrado el buen acuerdo entre las cinéticas de densificación obtenidas experimentalmente y las predichas por el modelo de sinterización de formación de Clusters en ausencia de cristalización concurrente.

The growth process via electrodeposition technique, of zinc oxide (ZnO) columns, on a glass substrate coated with conductor tin oxide and fluorine (FTO), is analysed. An exponential law of columns growth is determined to relate the columns height with exposition time in electrolytic mean. The columns growing is governed by an exponential law for electrolytic exposition times under 103 s, with constant temperature (65±2 ºC) and current density (i = 2,5 mA/ cm2); for exposition times larger than103 seconds this law is not necessary fulfilled. The specimen photoluminescence spectra at room temperature (300 K) and at low temperature (19 K) are analysed too. We also notice the photoluminescence spectra are related to the columns growing and branching.En el presente trabajo se analiza el proceso de crecimiento mediante electrodeposición, de columnas de ZnO sobre un sustrato de vidrio recubierto de óxido de estaño y fluor (FTO). Hemos determinado una ley de crecimiento de las columnas, de tipo exponencial, que relaciona la altura de éstas con el tiempo de exposición. Se observa que para tiempos de exposición inferiores a 103 s, manteniendo constante la temperatura (65±2 ºC) y la densidad de corriente (i = 2,5 mA/ cm2), las columnas crecen de acuerdo a una ley de tipo exponencial; para tiempos de exposición superiores a 103 no se cumple necesariamente esta ley. Se analizan los espectros de fotoluminiscencia de las muestras a la temperatura ambiente (300 K) y a baja temperatura (19K). Se observa, también, que los distintos espectros de fotoluminiscencia están relacionados con el crecimiento y ramificado de las columnas.

Hereinafter it is analysed the weldability of a spheroidal graphite cast iron of a established chemical composition. Shielded metal-arc welding (SMAW) have been used on casting samples of 300 x 90 x 10 mm, with a groove angle of 60º. It is also analysed the influence on the weldability of the chemical composition of the different electrodes used, Ni (56 % and 97,6 % each one) as well as the influence of the pre-heating temperature ( 350 ºC and 600 ºC) and the coldest velocity (at the air and at the furnace). The weldability is evaluated by tests of to bends and traction. Finally, microstructure analysis are performed on the joints: on the heat-affected-zone (the piece near the weld); the piece-weld interface; and the fusion-zone (the weld). Mechanical characteristics of the joint and its microstructure and with fractography analysis are correlated. In order to investigate the influence of the principal factors and interactions that take place in the process, a factorial design at two levels (high + and low -) was used, what meant to carry out 8 experiences.En el presente trabajo se analiza la soldabilidad de una fundición de grafito esferoidal (F.G.E.) de composición determinada, efectuando soldaduras por arco manual con electrodos revestidos, en probetas de esta fundición con dimensiones de 300 x 90 x 10 mm y ángulo de achaflanado de 60º. Se analiza la influencia en la soldabilidad de la composición de los distintos electrodos utilizados, base Ni (del 56 y 97,6 % respectivamente), la influencia de las temperaturas de precalentamiento (350 ºC y 600 ºC) y de la velocidad de enfriamiento (al aire y en el horno). La soldabilidad se evalúa mediante los ensayos de doblado y tracción. Se hace un análisis microestructural de las uniones: en el material a unir próximo a la soldadura; en la interfase metal - soldadura; y en el propio cordón de soldadura. Se correlacionan las características resistentes de la unión con la microestructura y con el análisis fractográfico. Para investigar la influencia de los principales factores e interacciones que intervinieron en el proceso, se utiliza un diseño factorial a dos niveles (alto + y bajo -), lo que supone realizar 8 experiencias replicadas.

The washback effect is particularly relevant when it comes to high-stakes tests, such as university entrance exams. This article presents a research study performed with the aim of determining the current influence of these exams on the teaching of chemistry in upper secondary education. The study was based on a questionnaire distributed among chemistry teachers --447 participants-- from across Spain. The results show that the chemistry content taught in upper secondary education is closer to what is requested in university entrance exams than to what teachers themselves believe to be important for students to learn. For the aspects examined, significant differences between regions were observed; in fact, relevant changes in the curriculum taught and the teaching methodology were apparent in those regions that incorporated content in their tests which was distinct from the traditional approach. Based on the findings, some implications and suggestions are drawn for future university entrance exams.

Background Bacteroides fragilis , an anaerobic gut bacterium and opportunistic pathogen, comprises two genetically divergent groups (or divisions) at the species level. Differences exist both in the core and accessory genomes and the beta-lactamase genes, with the cephalosporinase gene cep A represented only in division I and the carbapenemase gene cfi A only in division II. Methods Multidrug resistance in a clinical B. fragilis strain was examined by whole-genome sequencing. Results Strain CNM20200260 carried the antimicrobial resistance genes cep A, cfi A2, ant (6'), erm (F), mef (En2), est (T), tet (Q) and cat (A), along with 82-Phe mutation in gyr A (together with 47 amino acid changes in gyr A/B and par C/parE). bex A/B and other efflux pump genes were also observed. None of the detected insertion sequences was located upstream of cfi A2. The genome-based taxonomy coefficients (average nucleotide identity, DNA–DNA hybridization similarity and difference in genomic G + C%) with respect to genomes of the strains of B. fragilis division II and the novel species Bacteroides hominis (both cfi A-positive) met the criteria for CNM20200260 to belong to either species (>95%, >70% and <1%, respectively). No such similarity was seen with type strain NCTC 9343 or the representative genome FDAARGOS 1225 of B. fragilis (division I, cfi A-negative). Strain CNM20200260 harboured four out of nine Kyoto Encyclopedia of Genes and Genomes orthologues defined for division I and one of two defined for division II. Conclusions This is the first description of the co-occurrence of cep A and cfi A in a Bacteroides strain, confirming the complexity of the taxonomy of this species. [ABSTRACT FROM AUTHOR]

Objectives: To assess the ability of the International Endometrial Tumor Analysis (IETA)‐1 polynomial regression model to estimate the risk of endometrial cancer (EC) and other intracavitary uterine pathology in women without abnormal uterine bleeding. Methods: This was a retrospective study, in which we validated the IETA‐1 model on the IETA‐3 study cohort (n = 1745). The IETA‐3 study is a prospective observational multicenter study. It includes women without vaginal bleeding who underwent a standardized transvaginal ultrasound examination in one of seven ultrasound centers between January 2011 and December 2018. The ultrasonography was performed either as part of a routine gynecological examination, during follow‐up of non‐endometrial pathology, in the work‐up before fertility treatment or before treatment for uterine prolapse or ovarian pathology. Ultrasonographic findings were described using IETA terminology and were compared with histology, or with results of clinical and ultrasound follow‐up of at least 1 year if endometrial sampling was not performed. The IETA‐1 model, which was created using data from patients with abnormal uterine bleeding, predicts four histological outcomes: (1) EC or endometrial intraepithelial neoplasia (EIN); (2) endometrial polyp or intracavitary myoma; (3) proliferative or secretory endometrium, endometritis, or endometrial hyperplasia without atypia; and (4) endometrial atrophy. The predictors in the model are age, body mass index and seven ultrasound variables (visibility of the endometrium, endometrial thickness, color score, cysts in the endometrium, non‐uniform echogenicity of the endometrium, presence of a bright edge, presence of a single dominant vessel). We analyzed the discriminative ability of the model (area under the receiver‐operating‐characteristics curve (AUC); polytomous discrimination index (PDI)) and evaluated calibration of its risk estimates (observed/expected ratio). Results: The median age of the women in the IETA‐3 cohort was 51 (range, 20–85) years and 51% (887/1745) of the women were postmenopausal. Histology showed EC or EIN in 29 (2%) women, endometrial polyps or intracavitary myomas in 1094 (63%), proliferative or secretory endometrium, endometritis, or hyperplasia without atypia in 144 (8%) and endometrial atrophy in 265 (15%) women. The endometrial sample had insufficient material in five (0.3%) cases. In 208 (12%) women who did not undergo endometrial sampling but were followed up for at least 1 year without clinical or ultrasound signs of endometrial malignancy, the outcome was classified as benign. The IETA‐1 model had an AUC of 0.81 (95% CI, 0.73–0.89, n = 1745) for discrimination between malignant (EC or EIN) and benign endometrium, and the observed/expected ratio for EC or EIN was 0.51 (95% CI, 0.32–0.82). The model was able to categorize the four histological outcomes with considerable accuracy: the PDI of the model was 0.68 (95% CI, 0.62–0.73) (n = 1532). The IETA‐1 model discriminated very well between endometrial atrophy and all other intracavitary uterine conditions, with an AUC of 0.96 (95% CI, 0.95–0.98). Including only patients in whom the endometrium was measurable (n = 1689), the model's AUC was 0.83 (95% CI, 0.75–0.91), compared with 0.62 (95% CI, 0.52–0.73) when using endometrial thickness alone to predict malignancy (difference in AUC, 0.21; 95% CI, 0.08–0.32). In postmenopausal women with measurable endometrial thickness (n = 848), the IETA‐1 model gave an AUC of 0.81 (95% CI, 0.71–0.91), while endometrial thickness alone gave an AUC of 0.70 (95% CI, 0.60–0.81) (difference in AUC, 0.11; 95% CI, 0.01–0.20). Conclusion: The IETA‐1 model discriminates well between benign and malignant conditions in the uterine cavity in patients without abnormal bleeding, but it overestimates the risk of malignancy. It also discriminates well between the four histological outcome categories. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]