9300 research outputs found
Sort by
Methodology to predict mechanical properties of PA-12 lattice structures manufactured by powder bed fusion
Get PDFTopology optimization for weight reduction of additive manufacturing parts is commonly achieved throughout the creation of lattice structures, typically generated with beams of small size cross-section. In order to carry out accurate simulations of these lattice structures, knowing the mechanical behavior of pillars is required. In this paper, a methodology for determining the mechanical properties of small size pillars printed in PA-12 material, using polymer powder bed fusion (PBF) and in particular the Selective Laser Sintering (SLS) technology, is presented. The effect of defects originated during the manufacturing process on the macroscopic mechanical properties is studied and the mechanisms which influence these properties are analyzed. A methodology for the determination of these properties is proposed, based on a successive correction of the printed nominal diameters according to two approaches; one due to the outer skin of unmelted material and the other due to internal melting defects. Once the material properties are determined, as a function of the cross-section of the lattice pillars, the numerical simulation of lattice-type structures has been carried out and the degree of adjustment of the proposed methodology has been experimentally verified, obtaining good results. This validation provides a reliable method for the simulation of the macroscopic behavior of lattice-type structures with reduced sizes, taking into account the intrinsic defects generated during the printing process.The authors wish to acknowledge the funding received through the Junta de Castilla y León projects BU-002-P20 and INVESTUN/22/BU/0003 co-financed with FEDER funds, and the projects MR5W.P3 (C17. I01. P01. S21) and MR4W.P2 co-financed by JCyL and MICINN and the NextGenerationEU/PRTR funds
Valorisation of low-valued ray-finned fish (Labeobarbus nedgia) by enzymatic hydrolysis to obtain fish-discarded protein hydrolysates as functional foods
Get PDFThis study investigated the valorisation of low-valued ray-finned fish (Labeobarbus nedgia) (LB) muscle into valuable protein hydrolysates using three commercial enzymes (Alcalase®, Novozym®, and Protease®). After testing different enzyme concentrations (0–3 %, v/w) and temperatures (50–70 °C), the best results, including the highest degree of hydrolysis (DH) and antioxidant activity, were achieved when using Alcalase® at 3 % (v/w) and a temperature of 60 °C. However, Novozym® was found to be more resistant to high temperatures than Alcalase®. Functional properties of freeze-dried protein hydrolysates prepared using Alcalase® and Novozym®, at an enzyme concentration of 3 % (v/w) and a temperature of 60 °C, were determined. Both hydrolysates exhibited similar solubility, water and oil holding capacity, and foaming capacity and stability. This study demonstrated that the low-valued LB muscle can be used to produce a valuable protein hydrolysate, which could be used as a functional ingredient in the food industry.This work was funded by the Agencia Estatal de Investigación (AEI) and Ministerio de Ciencia e Innovación (MICINN) [grant number PID2019-104950RB-I00], by the AEI, MICINN, UE NextGenerationEU (Plan de Recuperación, Transformación y Resiliencia) [grant numbers TED2021-129311B-I00 and PDC2022-133443-I00] and by the Junta de Castilla y León (JCyL) and the European Regional Development Fund (ERDF) [grant number BU050P20]. P. Barea predoctoral contract was funded by JCyL and the European Social Fund (ESF) by ORDEN EDU/1868/2022, de 19 de diciembre. A.E. Illera post-doctoral contracts were funded by JCyL and ERDF through project BU050P20. R. Melgosa contract was funded by a Beatriz Galindo Research Fellowship [BG20/00182]
Spatial analysis of an Early Middle Palaeolithic kill/butchering site: the case of the Cuesta de la Bajada (Teruel, Spain)
Get PDFKill/butchering sites are some of the most important places for understanding the subsistence strategies of hunter-gatherer groups. However, these sites are not common in the archaeological record, and they have not been sufficiently analysed in order to know all their possible variability for ancient periods of the human evolution. In the present study, we have carried out the spatial analysis of the Early Middle Palaeolithic (MIS 9–8) site of Cuesta de la Bajada site (Teruel, Spain), which has been previously identified as a kill/butchering site through the taphonomic analysis of the faunal remains. Our results show that the spatial properties of the faunal and lithic tools distribution in levels CB2 and CB3 are well-preserved although the site is an open-air location. Both levels show a similar segregated (i.e. regular) spatial point pattern (SPP) which is different from the SPP identified at other sites with similar nature from the ethnographic and the archaeological records. However, although the archaeological materials have a regular distribution pattern, the lithic and faunal remains are positively associated, which is indicating that most parts of both types of materials were accumulated during the same occupation episodes, which were probably sporadic and focused on getting only few animal carcasses at a time.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. AM was funded by a grant from the Junta de Castilla y León, financed in turn by European Social Funds via the Consejería de Educación (BDNS 376062). This work is financed by CEN154P20 (co-financed by FEDER and JCyL) and PGC2018-093612-B-I00 (funded by MICIN/AEI/https://doi.org/10.13039/501100011033 and ERDF) projects. EM-Q is funded by a Post-Doc Xunta de Galicia Grant (ED481D-2022/023). LC-S is funded by J. Cascalheira’s ERC Consolidator grant (CoG—101045506)
The inversion of multiresponse partial least squares models, a useful tool to improve analytical methods in the framework of analytical quality by design
No full textAnalytical Quality by Design (AQbD) is the adaptation of Quality by Design (QbD) when it is applied to the development of an analytical method. The main idea is to develop the analytical method in such a way that the desired quality of the Critical Quality Attributes (CQAs), stated via the analytical target profile (ATP), is maintained while allowing some variation in the Control Method Parameters (CMPs).
The paper presents a general procedure for selecting factor levels in the CMPs to achieve the desired responses, characterized by the CQAs, when liquid chromatographic methods are to be used for the simultaneous determination of several analytes. In such a case, the CMPs are usually the composition of the ternary mobile phase, its flow rate, column temperature, etc., while typical CQAs refer to the quality of the chromatograms in terms of the resolution between each pair of consecutive peaks, initial and final chromatographic time, etc. The analytical target profile in turn defines the desired characteristics for the CQAs, the reason for the whole approach.
The procedure consists of four steps. The first is to construct a D-optimal combined design (mixture-process design) to select the domain and levels of the CMPs. The second step is to fit a PLS2 model to predict the analytical responses expressed in the ATP (the good characteristics of the chromatogram) as a function of the CMPs. The third step is the inversion of the PLS2 model to obtain the conditions necessary to obtain the preset ATP in the corresponding CQAs. The inversion is performed computationally in order to estimate the Pareto front of these responses, namely, a set of experimental conditions to perform the chromatographic determination for which the desired critical quality attributes are met. The fourth final step is to obtain the Method Operable Design Region (MODR), that is, the region where the CMPs can vary while maintaining the quality of the CQAs.
The procedure has been applied to some cases involving different analytes, all of which are regulated by the European Union due to their toxicity to human health, namely five bisphenols and ten polycyclic aromatic hydrocarbons.This work was supported by the Spanish MINECO (AEI/FEDER, UE), CTQ2017-88894-R and Consejería de Educación de la Junta de Castilla y León through project BU052P20. Both projects were co-financed with European Regional Development Funds
Exploring the morphology of adult tibia and fibula from Sima de los Huesos site in sierra de Atapuerca, Burgos, Spain
Get PDFThe analysis of the locomotor anatomy of Late Pleistocene Homo has largely focused on changes in proximal femur and pelvic morphologies, with much attention centered on the emergence of modern humans. Although much of the focus has been on changes in the proximal femur, some research has also been conducted on tibiae and, to a lesser extent, fibulae. With this in mind, we present one of the largest samples of the same population of human tibiae and fibulae from the Middle Pleistocene to determine their main characteristic traits and establish similarities and differences, primarily with those of Neanderthals and modern humans, but also with other Middle Pleistocene specimens in the fossil record. Through this study, we established that the Middle Pleistocene population from the Sima de los Huesos (Atapuerca, Burgos, Spain) had lower leg long bones similar to those of Neanderthals, although there were some important differences, such as bone length, which this fossil individuals resembled those of modern humans and not to Neanderthals. This fact is related to the crural index and leg length, even though we do not have any true association between femora and tibiae yet, it has implications for establishing locomotor efficiency and climate adaptation.Grant PID2021-122355NB-C31 funded by MCIN/AEI/ 10.13039/501100011033 and “ERDF A way of making Europe”, Fieldwork at the Atapuerca sites is funded by the Junta de Castilla y León and the Fundación Atapuerca
Sustainability in times of crisis: Female employment during COVID‐19
No full textIn periods of crisis, companies face a financial reality that forces them to decide whether to maintain their commitment to sustainability or prioritize their financial returns. The study of what happened during the COVID-19 pandemic is vital, given the hard blow it has implied for business and, consequently, for employment. Thus, this paper seeks to determine whether the business commitment to sustainability policies focused on employment and gender diversity translates into concrete results. In a sample of 1761 multinationals (8963 observations) during the 2015–2020 period, we found that the pandemic has harmed employment at the microeconomic level. However, this impact is moderated by the level of responsibility that companies have with their workers. Therefore, the most sustainable companies have been more reluctant to reduce their workforce and even more so when they are women. These results help to position sustainability performance as a way to achieve gender equality at the business level.The financial support provided to Maria Victoria Uribe Bohorquez by Spanish Ministry of Science & Innovation (Grant TED2021-129520B-I00) and FEDER and Junta de Castilla y León (Grant BU069P20) is gratefully acknowledged. The financial support provided to Isabel María García Sánchez Junta de Castilla y León and Fondo Europeo de Desarrollo Regional (Grant CLU-2019-03 Unidad de Excelencia “GECOS-Gestión Económica para la Sostenibilidad”) is gratefully acknowledged
Evaluation of an augmented reality APP for children with dyslexia: a pilot study
No full textDesde hace unas décadas se están integrando en el ámbito educativo y en el tratamiento pedagógico diferentes tecnologías emergentes. Este artículo presenta la evaluación de una aplicación de realidad aumentada (RA) para trabajar con estudiantes con dislexia. El objetivo del artículo es conocer la percepción de los jóvenes con dislexia (10 - 15 años) tras la utilización de la aplicación de RA empleando el Modelo de Aceptación Tecnológica y, conocer la valoración de los aspectos técnicos, estéticos y facilidad de navegación de la aplicación mediante un cuestionario ad hoc. En este estudio piloto han participado siete niños/as con dislexia. La metodología utilizada ha sido un estudio empírico – descriptivo de tipo observacional. Los primeros resultados muestran que el nivel de aceptación hacia esta tecnología es aceptable, rondando valores intermedios de 3 en todas las dimensiones del Modelo TAM. Los aspectos que más destacan los entrevistados de la aplicación son la calidad de los textos, la narrativa del juego, el orden en la secuencia de las actividades, la utilización de la memoria durante el juego y la ambientación del videojuego en planetas. Por lo tanto, se puede considerar que esta aplicación de RA es útil para trabajar las necesidades de los niños/as con dislexia desde una perspectiva lúdica.Different emerging technologies have been integrated into the field of education for several decades. This article presents the evaluation of an augmented reality (AR) application for working with students with dyslexia. The aim of this article is to find out the perception of young people with dyslexia (aged 10 - 15) after using the AR application using the Technological Acceptance Model and to find out their evaluation of the technical, aesthetic and ease of navigation aspects of the application by means of an ad hoc questionnaire. Seven children with dyslexia participated in this pilot study. The methodology used was an empiricaldescriptive observational study. The first results show that the level of acceptance towards this technology is acceptable, with intermediate values of 3 in all dimensions of the TAM Model. The most outstanding aspects of the application are the quality of the texts, the narrative of the game, the order in the sequence of the activities, the use of memory during the game and the setting of the video game on planets. Therefore, this AR application can be considered useful for working with the needs of children with dyslexia from a playful perspective.This work has been co-funded by the Erasmus+ programme of the European Union through the European project “Fostering inclusive learning for children with dyslexia in Europe by providing easy-to-use virtual and/or augmented reality tools and guidelines (FORDYS-VAR)”, reference 2018-1-ES01-KA201-050659