Determination of Solidification of Rigidity Point Temperature Using a New Method

This work aims to calculate the rigidity point temperature of aluminum alloys by three new methods and compare them with currently employed methods. The influence of major and minor alloying elements over the rigidity point temperature is also discussed. Until now it has been difficult to determine the exact temperature of the rigidity point, since small variations in the data obtained give variable results, making it difficult to automate the process with high accuracy. In this work we suggested three new mathematic methods based on the calculation of higher order derivatives of (dT/dt) with respect to time or temperature compared to those currently employed. A design of experiments based on the Taguchi method was employed to compare the effect of the major and minor alloying elements for the AlSi10Mg alloy, and to evaluate the accuracy of each developed method. Therefore, these systems will allow better automation of rigidity point temperature (RPT) determination, which is one of the most important solidification parameters for solidification simulators. The importance of the correct determination of this parameter lies in its relation to quality problems related to solidification, such as hot tearing. If the RPT presents very low-temperature values, the aluminum casting will be more sensitive to hot tearing, promoting the presence of cracks during the solidification process. This is why it is so important to correctly determine the temperature of the RPT. An adequate design of chemical composition by applying the methodology and the novel methods proposed in this work, and also the optimization of process parameters of the whole casting process with the help of the integrated computational modeling, will certainly help to decrease any internal defective by predicting one of the most important defects present in the aluminum industry.This research was partially funded by the Basque Government through the Etorgai Programme 2016, under the Filing Identification Number ZE-2016/00018 and the Elkartek Programme 2020, KK-2020-00047 for research, technological development and demonstration

Solid Fraction Determination at the Rigidity Point by Advanced Thermal Analysis

The aim of this work is to determine the Solid Fraction (SF) at the rigidity point (FRP) by applying advanced thermal analysis techniques. The variation of the FRP value is important to explain the solidification behavior and the presence or absence of defects in aluminum alloys. As the final alloy composition plays a key role on obtained properties, the influence of major and minor alloying elements on FRP has been studied. A Taguchi design of experiments and a previously developed calculating method, based on the application of high rank derivatives has been employed to determinate first the rigidity point temperature (RPT) and after the corresponding FRP for AlSi10Mg alloys. A correlation factor of r2 of 0.81 was obtained for FRP calculation formula in function of the alloy composition.This work has been partially funded by the Basque Government through the HAZITEK Programme ZE-2018/00018 (FACOEE) and ELKARTEK KK-2020_00047 (CEMAP)

Solid Fraction Determination at the Rigidity Point by Advanced Thermal Analysis

The aim of this work is to determine the Solid Fraction (SF) at the rigidity point (FRP) by applying advanced thermal analysis techniques. The variation of the FRP value is important to explain the solidification behavior and the presence or absence of defects in aluminum alloys. As the final alloy composition plays a key role on obtained properties, the influence of major and minor alloying elements on FRP has been studied. A Taguchi design of experiments and a previously developed calculating method, based on the application of high rank derivatives has been employed to determinate first the rigidity point temperature (RPT) and after the corresponding FRP for AlSi10Mg alloys. A correlation factor of r2 of 0.81 was obtained for FRP calculation formula in function of the alloy composition.This work has been partially funded by the Basque Government through the HAZITEK Programme ZE-2018/00018 (FACOEE) and ELKARTEK KK-2020_00047 (CEMAP)

Compound Formation And Microstructure Of As-Cast High Entropy Aluminums

The aim of this work is to study the microstructure of four high entropy alloys (HEAs) produced by large scale vacuum die casting. Al40Cu15Mn5Ni5Si20Zn15, Al45Cu15Mn5Fe5Si5Ti5Zn20, Al35Cu5Fe5Mn5Si30V10Zr10, and Al50Ca5Cu5Ni10Si20Ti10 alloys formed amixture of different structures, containing intermetallic compound (IC) and solid solution (SS) phases. The phases observed in the casting alloys were compared with the equilibrium phases predicted by Thermo-Calc. The measured densities varied from 3.33 g/cm(-3) to 5.07 g/cm(-3) and microhardness from 437 Hv to 887 Hv. Thus, the microhardness and estimated strength/density ratios are significantly higher than other lightweight high entropy alloys (LWHEAs).This work has been partially funded by the Basque Government through the project Elkartek: KK-2017/00007

Análisis estratigráfico de la muralla sur de Contrebia Leukade (Aguilar del Río Alhama, La Rioja)

The stratigraphic analysis of the south wall of the Contrebia Leukade settlement is part of a project to restore the settlement. The analysis has shown the evolution of the settlement to be far more complex than was previously thought. In addition to the stratigraphic analysis, the present study also tackles the chronology problem of the earlier phases of the settlement.El análisis estratigráfico de la muralla sur de Contrebia Leukade se inscribe dentro del proyecto de restauración de la misma y ha permitido documentar una evolución de sus estructuras mucho más compleja de lo planteado hasta el momento. Además de su análisis estratigráfıco, en el presente estudio se aborda también el problema de la cronología de sus fases más tempranas

Designing for Shape Memory in Additive Manufacturing of Cu–Al–Ni Shape Memory Alloy Processed by Laser Powder Bed Fusion

Shape memory alloys (SMAs) are functional materials that are being applied in practically all industries, from aerospace to biomedical sectors, and at present the scientific and technologic communities are looking to gain the advantages offered by the new processing technologies of additive manufacturing (AM). However, the use of AM to produce functional materials, like SMAs, constitutes a real challenge due to the particularly well controlled microstructure required to exhibit the functional property of shape memory. In the present work, the design of the complete AM processing route, from powder atomization to laser powder bed fusion for AM and hot isostatic pressing (HIP), is approached for Cu–Al–Ni SMAs. The microstructure of the different processing states is characterized in relationship with the processing parameters. The thermal martensitic transformation, responsible for the functional properties, is analyzed in a comparative way for each one of the different processed samples. The present results demonstrate that a final post–processing thermal treatment to control the microstructure is crucial to obtain the expected functional properties. Finally, it is demonstrated that using the designed processing route of laser powder bed fusion followed by a post–processing HIP and a final specific thermal treatment, a satisfactory shape memory behavior can be obtained in Cu–Al–Ni SMAs, paving the road for further applications.This research was supported by the Industry Department of the Basque Government through the ELKARTEK–CEMAP (KK–2020/00047) project, as well as from the GIU–17/071 from the University of the Basque Country UPV/EHU. Financial support was also received from the Spanish Ministry of Economy and Competitiveness, MINECO, through the project MAT2017-84069P. This work made use of the facilities from the Electronic Microscopy and Material Microanalysis Service of the SGIKER from the UPV/EHU. M.P.-C. acknowledges the pre–doctoral grant (PRE_2019_2_0268) from the Education Department of the Basque Country. J.F.G.-C. thanks the post–doctoral grant (ESPDOC18/37) from the UPV/EHU

Preclinical studies with glioblastoma brain organoid co-cultures show efficient 5-ALA photodynamic therapy

Abstract: Background: The high recurrence of glioblastoma (GB) that occurs adjacent to the resection cavity within two years of diagnosis urges an improvement of therapies oriented to GB local control. Photodynamic therapy (PDT) has been proposed to cleanse infiltrating tumor cells from parenchyma to ameliorate short long-term progression-free survival. We examined 5-aminolevulinic acid (5-ALA)- mediated PDT effects as therapeutical treatment and determined optimal conditions for PDT efficacy without causing phototoxic injury to the normal brain tissue. Methods: We used a platform of Glioma Initiation Cells (GICs) infiltrating cerebral organoids with two different glioblastoma cells, GIC7 and PG88. We measured GICs-5-ALA uptake and PDT/5-ALA activity in dose-response curves and the efficacy of the treatment by measuring proliferative activity and apoptosis. Results: 5-ALA (50 and 100  g/mL) was applied, and the release of protoporphyrin IX (PpIX) fluorescence measures demonstrated that the emission of PpIX increases progressively until its stabilization at 24 h. Moreover, decreased proliferation and increased apoptosis corroborated the effect of 5-ALA/PDT on cancer cells without altering normal cells. Conclusions: We provide evidence about the effectiveness of PDT to treat high proliferative GB cells in a complex in vitro system, which combines normal and cancer cells and is a useful tool to standardize new strategic therapies

Yield estimation of forage oat (Avena sativa L.) Chihuahua variety: ruler and plate methods

Objetive: To analyze forage estimations with the direct method and the plant height. Diseño/Metodología/Aproximación: The treatments were the plants age, assessed in a random block design, with three repetitions. Simple linear regressions were carried out and adjusted using the SPSS statistical software. Resultados: The highest and lowest yields occurred at 105 and 30 days after sowing (DAS), with 5,412 and 783 kg DM ha-1, respectively. Height with the rule had a significant effect on forage production, with an R2 of 0.83. For each increase per cm the plants increased 56,134 kg DM ha-1. The height with the plate had an R2 of 0.97, so that 65.032 kg DM ha-1 are produced for each cm in height. Limitaciones del estudio/implicaciones: None Hallazgos/conclusiones: The forage accumulation in Avena sativa L., var. Chihuahua varied depending on the age of the plant. The heights calculated with the plate method, had greater reliability for the forage yield estimate, compared to the graduated rule method

El sitio prehispánico La Noria, ciudad de Buenos Aires

En este trabajo se presentan los artefactos y ecofactos recuperados y las estructuras identificadas en el sitio arqueológico La Noria. Este depósito se localiza en el ángulo sudoeste de la ciudad de Buenos Aires, sobre la margen izquierda del río Matanzas. El registro fue generado por grupos de cazadores-recolectores del Holoceno tardío prehispánico. La colección obtenida se compone de alfarería de formas simples y tamaño pequeño, decorada preponderantemente mediante líneas geométricas incisas y secundariamente por impresiones. El conjunto lítico está compuesto por artefactos de retoque unifacial directo, confeccionado en cuarcita, calcedonia y caliza silicificada. La colección faunística se compone principalmente de venado de las pampas, pero también incluye otros taxones típicos de la llanura pampeana. Cinco fechados efectuados mediante termoluminiscencia acotan el registro recuperado entre 728 ± 56 y 861 ± 67 años AP.In this paper the artifacts and ecofacts recovered at La Noria site are presented, as well as the structures identified in it. The archaeological deposit is located in the southwest corner of the city of Buenos Aires, on the left bank of the Matanzas River. The record was generated by hunter-gatherer groups of the pre-Hispanic Late Holocene. It consists of simple shapes and small size pottery, decorated by incised and impressed designs. The lithic set is composed of unifacial retouched artifacts, made of quartzite, chalcedony and silicified limestone. The faunal collection consists mainly of pampas deer, but also includes other taxa typical of the Pampas plain. Five dates carried out by thermoluminescence delimit chronologically the record between 728 ± 56 and 861 ± 67 years BP.Fil: Camino, Ulises Adrián. Universidad de Buenos Aires. Facultad de Arquitectura, Diseño y Urbanismo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Schavelzon Chavin, Daniel Gaston. Universidad de Buenos Aires. Facultad de Arquitectura, Diseño y Urbanismo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Azkárate, Agustín. Universidad del País Vasco; EspañaFil: Loponte, Daniel Marcelo. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Solaun, José Luis. Universidad del País Vasco; EspañaFil: Martínez, Angel. Universidad del País Vasco; EspañaFil: Sánchez, Iban. Universidad del País Vasco; EspañaFil: Cavallotto, José Luis. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; Argentin