Effect of Ce Content on Microstructure-Toughness Relationship in the Simulated Coarse-Grained Heat-Affected Zone of High-Strength Low-Alloy Steels

The study aimed to identify a moderate degree of Ce addition to improve the toughness in the simulated coarse-grained heat-affected zone (CGHAZ) of high-strength low-alloy steels, based on the effect of the Ce content on particle characteristics, microstructure and impact toughness. Three steels with 0.012 wt.%, 0.050 wt.% and 0.086 wt.% Ce content were subjected to 100 kJ/cm heat input in their thermal welding cycles. The particles and microstructures in the simulated CGHAZ of each steel were characterized and the impact-absorbance energy levels were measured at −20 °C. The results indicated that Ce2O2S inclusion compounds were gradually modified to CexSy-CeP and CeP with the increasing of the Ce content. A higher fraction of acicular ferrite was formed in the 0.012 wt.%-Ce-treated steel due to the lower mismatch between Ce2O2S and α-Fe. Furthermore, a lower fraction of M-A constituent was obtained in the 0.012 wt.%-Ce-treated steel. As a result, superior toughness and a typical amount of ductile fracture were detected in the simulated CGHAZ of the 0.012 wt.%-Ce-treated steel. Compared with the 0.012 wt.%-Ce-treated steel, a smaller prior austenite grain was observed in the 0.086 wt.%-Ce-treated steel because of the segregation of CeP at the grain boundary. However, the larger size and density of CeP led to poor toughness in the CGHAZ of the 0.086 wt.%-Ce-treated steel.

Efficient photocatalytic hydrogen production over Ce/ZnO from aqueous methanol solution

Ce/ZnO crystallites along with bare ZnO were prepared by solution free mechanochemical method and characterized with powder XRD, SEM, EDX, XPS, UV–Visible and Photoluminescence (PL) spectra. The visible light photocatalytic performance of these materials was investigated for H2 evolution with the aqueous 10vol% methanol solution under one sun conditions using solar simulator. X-ray diffraction data suggests the hexagonal wurtzite structure for Ce/ZnO crystallites and the incorporation of Ce4+ ion in ZnO is supported by the shifting of XRD peaks to lower Bragg angles that indicate lattice expansion. With the increase of Ce content in ZnO, the crystallite size of Ce/ZnO decreases and the specific surface area increases. UV–Visible spectra propose the decrease in optical band gap of Ce incorporated ZnO with the increase of Ce content up to 3 mol. %. The XPS analysis supports the incorporation of Ce4+ in Ce/ZnO. The PL spectra propose that, with the insertion of Ce ions into ZnO, intensity of UV emission band decreases that reflects the low recombination rate of photogenerated charge carriers, which is responsible for higher photocatalytic H2 production. The extent of hydrogen production is affected by calcination temperature of Ce/ZnO. 2 mol. % Ce incorporated ZnO calcined at 600 °C produces43 μmolh−1 g−1 of hydrogen.

Impacto positivo de una master class online de percusión corporal para docentes (Positive impact of an online body percussion master class for teachers)

La formación permanente relacionada con la expresión corporal (EC) parece ser escasa y poco atractiva para los/las docentes. Sin embargo, se conoce que existen formaciones específicas de percusión corporal (PC) que están generando emociones positivas, convirtiéndose en una fuente de motivación para el profesorado y un reto para su alumnado. Esta investigación pretende averiguar los cambios generados en la percepción del profesorado respecto a los conocimientos y posibilidades que puede tener la PC para implementarse en Educación Física (EF) como un contenido de EC. Se trata de una investigación – acción donde se diseñó e implementó una Master Class online específica de PC y se esperó observar un cambio en la opinión del participante después de la experiencia. Para la evaluación inicial y final de la percepción del profesorado respecto a la PC, se administró la parte del cuestionario COPEFEAEC, que hace referencia a la PC y que está en proceso de validación. La muestra final que participó en el estudio PRE-POST, fue de 92 coordinadores de educación en Cataluña, siendo el género (hombre/mujer) equilibrado en casi un 50%, con un rango de edad de 20 a 60 años, un 73.9% de educación primaria y un 26.1% en secundaria, estando especializado en EF casi el 98%. Se obtuvieron diferencias significativas ( p<.001) respecto a los conocimientos de PC ya que al terminar la sesión, un 58.7% expresó haber aumentado sus conocimientos. Se observó un mayor grado de acuerdo en la situación POST respecto a aceptar la PC como contenido de EC en las clases de EF. Abstract. Permanent training related to corporal expression (CE) appears to be scarce and unattractive for teachers. However, it is known that there are specific body percussion (BP) formations that are generating positive emotions, becoming a source of motivation for teachers and a challenge for their students. This research aims to find out the changes generated in the perception of teachers regarding the knowledge and possibilities that the BP can have to be implemented in Physical Education (PE) as a CE content. It is an action research where a BP-specific online Master Class was designed and implemented and it was expected to observe a change in the participant's opinion after the experience. For the initial and final evaluation of the teachers' perception regarding BP, part of the COPEFEAEC questionnaire that refers to BP and it is in validation process, was administered. The final sample that participated in the PRE-POST study consisted of 92 education coordinators in Catalonia, with gender (male / female) balanced by almost 50%, with an age range of 20 to 60 years old, 73.9% of primary education and 26.1% in secondary, being specialized in PE almost 98%. Significant differences (p <.001) were obtained with respect to BP knowledge, since at the end of the session, 58.7% expressed having increased their knowledge. A higher degree of agreement was observed in the POST situation regarding accepting BP as EC content in PE classes.

Abundance, fatty acid composition and saturation index of neutral lipids in colorectal cancer cell lines

Lipid droplets, the dynamic organelles that store triglycerides (TG) and cholesterol esters (CE), are highly accumulated in colon cancer cells. This work studies the TG and CE subspecies profile in colon carcinoma cell lines, SW480 derived from primary tumor, and SW620 derived from a metastasis of the same tumor. It was previously reported that the total TG and CE content is dramatically higher in SW620 cells; however, TG and CE subspecies profile has not been investigated in detail. The work presented here confirms that the total TG and CE content is significantly higher in the SW620 cells. Moreover, the fatty acid (FA) composition of TG is significantly altered in the SW620 cells, with significant decrease in the abundance of saturated triglycerides. This resulted in a significantly decreased TG saturation index in the SW620 cells. The saturation index of CE was also significantly decreased in the SW620 cells.

ZnO Nanoparticles with Controllable Ce Content for Efficient Photocatalytic Degradation of MB Synthesized by the Polyol Method

This paper reports on the synthesis of Ce-doped ZnO (CZO) nanoparticles (NPs) by an alternative polyol method at low temperature. The method, facile and rapid, uses acetate-based precursors, ethylene glycol as solvent, and polyvinylpyrrolidone as capping agent. The effects of the Ce-doping concentration (ranging from 0 to 8.24 atomic%) on the structural, morphological, compositional, optical, luminescence, and photocatalytic properties of the NPs were investigated by several techniques. The structural findings confirmed that the CZO NPs have a typical hexagonal wurtzite-type structure with a preferred orientation along the (101) plane. The results obtained by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) revealed that the NPs size decreased (from ~30 to ~16 nm) with an increase in the Ce-doping concentration. Energy Dispersive X-Ray Spectroscopy (EDS) and High Resolution Transmission Microscopy (HRTEM) results confirmed the incorporation of Ce ions into the ZnO lattice. Ce-doping influences the photoluminescence (PL) emission compared to that of pure ZnO. The PL emission is related to the presence of different kinds of defects, which could take part in charge transfer and/or trapping mechanisms, hence playing an essential role in the photocatalytic activity (PCA). In fact, in this work we report an enhancement of PCA as a consequence of Ce-doping. In this sense, the best results were obtained for samples doped with 3.24 atomic%, that exhibited a photocatalytic degradation efficiency close to 99% after 60 min ultraviolet (UV) illumination, thus confirming the viability of Ce-doping for environmental applications.