Effect of the biobased polyols chemical structure on high performance thermoset polyurethane properties

The sustainability of the polymeric materials has become a fundamental challenge; therefore, the development of new biobased formulations has gained increasing interest. Thermoset polyurethanes (PURs) present high performance and are a competitive solution for structural composites. However, polyols used in the PUR synthesis are typically from petrochemical origin. Nowdays, a broad range of biobased polyols is available in the market, but there is not yet a specific formulation for high performance PURs composites. The aim of this work was to study the effect of biobased polyols' characteristics in the PUR processing and final properties. In addition, biobased polyol features to synthesize BIO-PURs suitable for structural applications were stablished. The viscosity and reactivity were studied by means of rheology and differential scanning calorimetry (DSC). Thermal and mechanical properties were studied through thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and flexural tests. The results obtained demonstrated the dramatic influence of polyols’ nature on BIO-PUR/PUR properties and their effect on the crosslink density. It was observed that using a high functionality and high hydroxyl index biobased polyol, it was possible to synthesize high performance BIO-PUR suitable for structural composites.We gratefully acknowledge the Basque Government for the financial support through the ELKARTEK 2021 (Project NEOMAT KK-2021/00059) program and in the frame of Grupos Consolidados (IT-1690-22). The authors also acknowledge the University of the Basque Country (UPV/EHU) in the frame of GIU18/216 Research Group and the Macrobehavior-Mesostructure-Nanotechnology SGIker unit

The influence of individual perceptions and the urban/rural environment on nascent entrepreneurship

Individual perceptions have been shown to affect the decision to start a new firm. This decision is also contingent upon the context in which actions are taken. However, not much is known about the joint impact of entrepreneurs' perceptions and the urban/rural environment where the firm is created. The purpose of this paper is to examine how nascent entrepreneurship is influenced by individual perceptions and the urban/rural context. Using data from the Spanish GEM project, the results of a series of logistic regression models indicate that opportunity perception and self-efficacy have a positive influence on the probability of becoming a nascent entrepreneur. Interestingly, we also find that individuals in rural areas who perceive new opportunities are more likely to become nascent entrepreneurs rather than those who live in urban ones.Las percepciones subjetivas de los emprendedores han servido para explicar la decisión al emprender una nueva iniciativa empresarial. Sin embargo, esta decisión también está influida por el entorno en el que se toma. En este sentido, existe poca literatura sobre el impacto conjunto de las percepciones de los emprendedores y el entorno rural o urbano en el que se crea la empresa. Por ello, el propósito de este artículo es analizar cómo el emprendimiento naciente está condicionado por las percepciones individuales y el entorno, rural o urbano, en el que se ubica el emprendedor. Los resultados de una serie de modelos de regresión logística sobre los datos del proyecto GEM para España, indican que la percepción de oportunidad y la confianza en las propias habilidades tienen un impacto positivo en la probabilidad de convertirse en emprendedor naciente. Asimismo destaca que, en comparación con los individuos que residen en entornos urbanos, los individuos en áreas rurales que perciben oportunidades tienen una mayor probabilidad de convertirse en emprendedores nacientes

Juegos para presentar conceptos básicos de Arquitectura de Computadores

La mayoría de estudiantes de primer año en el grado de Inteligencia Artificial (IA) no ha tenido contacto previo con la arquitectura de computadores, aunque se están haciendo esfuerzos para cambiar esta situación. Esto supone un salto muy drástico a temas abstractos sin ningún soporte sobre el que sostenerse. Por esta razón, en la asignatura Introducción a la Arquitectura de Computadores, se plantea hacer una pequeña introducción mediante juegos de los conceptos más básicos para crear ese sustento sobre el que poder construir, de forma atractiva, el resto de conocimientos que se requieren en la asignatura. El aprendizaje basado en juegos es una metodología interactiva e inmersiva que puede hacer que el proceso de aprendizaje sea más atractivo y agradable para el alumnado, permitiéndole comprometerse activamente con los conceptos que está aprendiendo, en lugar de limitarse a recibir información de forma pasiva. Por esto se pensó que esta metodología, en contraposición a la tradicional, ayudaría al alumnado a asimilar mejor los conceptos básicos. Se han llevado a cabo dos intervenciones de las que se ha concluido que, siendo el grado de aprendizaje del alumnado similar, el aprendizaje basado en juegos motiva más al alumnado.Most first year students in the Artificial Intelligence degree have had no previous contact with computer architecture, although efforts are being made to change this situation. This is a very drastic leap to abstract topics without any support on which to build, also taking into account that less hours will be devoted to the architecture branch than in Computer Engineering degree. For this reason, this paper proposes a small introduction through games of the most basic concepts to create the needed support on which to build, in an attractive way, the rest of the knowledge required in the Introduction to Computer Architecture subject. Game-based learning an interactive and immersive methodology that can make the learning process more attractive and enjoyable for students, allowing them to actively engage with the concepts they are learning, rather than just passively receiving information. For these reasons, it was thought that this methodology would help students to assimilate the basic concepts better than traditional methodologies. Two interventions have been carried out, from which it has been concluded that, although the level of student learning is similar, game-based learning better motivates students.Este trabajo ha sido financiado por el Departamento Educación del Gobierno Vasco (ADIAN, IT1437-22) y el Servicio de Asesoramiento Educativo de la Universidad Del País Vasco / Euskal Herriko Unibertsitatea (IKDi321-18)

Occupational exposure to nano-TiO2 in the life cycle steps of new depollutant mortars used in construction

The present work is focused on the measurement of workers exposure to nano-TiO2 in the life cycle steps of depollutant mortars. It has been done in the framework of the SCAFFOLD project, which aims at the management of potential risks arising from the use of manufactured nanomaterials in construction. Main findings can be summarized as follows: (1) The occupational exposure to nano- TiO2 is below 0.3 mg/m3 for all measured scenarios. The highest concentrations were measured during the cleaning task (in the nano- TiO2 manufacturing process) and during the application (spraying) of depollutant coatings on a wall. (2) It was found a high release of particles above the background in several tasks as expected due to the nature of the activities performed. The maximum concentration was measured during drilling and during adding powder materials (mean total particle concentration up to 5.591E+04 particles/cm3 and 5.69E+04 particles/cm3). However, considering data on total particle concentration released, no striking differences have been observed when tasks have been performed using conventional materials in the sector (control) and when using materials doped with nano-objects.European Commission's FP

Strategies, methods and tools for managing nanorisks in construction

This paper presents a general overview of the work carried out by European project SCAFFOLD (GA 280535) during its 30 months of life, with special emphasis on risk management component. The research conducted by SCAFFOLD is focused on the European construction sector and considers 5 types of nanomaterials (TiO2, SiO2, carbon nanofibres, cellulose nanofibers and nanoclays), 6 construction applications (Depollutant mortars, selfcompacting concretes, coatings, self-cleaning coatings, fire resistant panels and insulation materials) and 26 exposure scenarios, including lab, pilot and industrial scales. The document focuses on the structure, content and operation modes of the Risk Management Toolkit developed by the project to facilitate the implementation of "nano-management" in construction companies. The tool deploys and integrated approach OHSAS 18001 - ISO 31000 and is currently being validated on 5 industrial case studies.Research carried out by project SCAFFOLD was made possible thanks to funding from the European Commission, through the Seventh Framework Programme (GA 280535

Prospective individual patient data meta-analysis of two randomized trials on convalescent plasma for COVID-19 outpatients

Data on convalescent plasma (CP) treatment in COVID-19 outpatients are scarce. We aimed to assess whether CP administered during the first week of symptoms reduced the disease progression or risk of hospitalization of outpatients. Two multicenter, double-blind randomized trials (NCT04621123, NCT04589949) were merged with data pooling starting when = 50 years and symptomatic for <= 7days were included. The intervention consisted of 200-300mL of CP with a predefined minimum level of antibodies. Primary endpoints were a 5-point disease severity scale and a composite of hospitalization or death by 28 days. Amongst the 797 patients included, 390 received CP and 392 placebo; they had a median age of 58 years, 1 comorbidity, 5 days symptoms and 93% had negative IgG antibody-test. Seventy-four patients were hospitalized, 6 required mechanical ventilation and 3 died. The odds ratio (OR) of CP for improved disease severity scale was 0.936 (credible interval (CI) 0.667-1.311); OR for hospitalization or death was 0.919 (CI 0.592-1.416). CP effect on hospital admission or death was largest in patients with <= 5 days of symptoms (OR 0.658, 95%CI 0.394-1.085). CP did not decrease the time to full symptom resolution

Characterization of cellulosic samples obtained from sisal fibers

In this work the reaction conditions of different chemical treatments used for the isolation of nanocellulose were evaluated. This study clarified the effect of different reaction conditions (time or concentration) on the structure and composition of the cellulosic fibers, To achieve this objective, different chemical, thermal and morphological characterization techniques were used after each chemical treatment and the most suitable reaction conditions were selected

The influence of individual perceptions and the urban/rural environment on nascent entrepreneurship

Individual perceptions have been shown to affect the decision to start a new firm. This decision is also contingent upon the context in which actions are taken. However, not much is known about the joint impact of entrepreneurs' perceptions and the urban/rural environment where the firm is created. The purpose of this paper is to examine how nascent entrepreneurship is influenced by individual perceptions and the urban/rural context. Using data from the Spanish GEM project, the results of a series of logistic regression models indicate that opportunity perception and self-efficacy have a positive influence on the probability of becoming a nascent entrepreneur. Interestingly, we also find that individuals in rural areas who perceive new opportunities are more likely to become nascent entrepreneurs rather than those who live in urban ones.Las percepciones subjetivas de los emprendedores han servido para explicar la decisión al emprender una nueva iniciativa empresarial. Sin embargo, esta decisión también está influida por el entorno en el que se toma. En este sentido, existe poca literatura sobre el impacto conjunto de las percepciones de los emprendedores y el entorno rural o urbano en el que se crea la empresa. Por ello, el propósito de este artículo es analizar cómo el emprendimiento naciente está condicionado por las percepciones individuales y el entorno, rural o urbano, en el que se ubica el emprendedor. Los resultados de una serie de modelos de regresión logística sobre los datos del proyecto GEM para España, indican que la percepción de oportunidad y la confianza en las propias habilidades tienen un impacto positivo en la probabilidad de convertirse en emprendedor naciente. Asimismo destaca que, en comparación con los individuos que residen en entornos urbanos, los individuos en áreas rurales que perciben oportunidades tienen una mayor probabilidad de convertirse en emprendedores nacientes

In vitro biocompatibility and antimicrobial activity of poly(ε-caprolactone)/montmorillonite nanocomposites

A triblock copolymer based on poly(ε-caprolactone) (PCL) and 2-(N,N-diethylamino)ethyl methacrylate (DEAEMA)/2-(methyl-7-nitrobenzofurazan) amino ethyl acrylate (NBD-NAcri), was synthesized via atom transfer radical polymerization (ATRP). The corresponding chlorohydrated copolymer, named as PCL-b-DEAEMA, was prepared and anchored via cationic exchange on montmorillonite (MMT) surface. (PCL)/layered silicate nanocomposites were prepared through melt intercalation, and XRD and TEM analysis showed an exfoliated/intercalated morphology for organomodified clay. The surface characterization of the nanocomposites was undertaken by using contact angle and AFM. An increase in the contact angle was observed in the PCL/MMT(PCL-b-DEAEMA) nanocomposites with respect to PCL. The AFM analysis showed that the surface of the nanocomposites became rougher with respect to the PCL when MMTk10 or MMT(PCL-b-DEAEMA) was incorporated, and the value increased with the clay content. The antimicrobial activity of the nanocomposites against B. subtilis and P. putida was tested. It is remarkable that the biodegradation of PCL/MMT(PCL-b-DEAEMA) nanocomposites, monitored by the production of carbon dioxide and by chemiluminescence emission, was inhibited or retarded with respect to the PCL and PCL/1-MMTk10. It would indicate that nature of organomodifier in the clay play an important role in B. subtilis and P. putida adhesion processes. Biocompatibility studies demonstrate that both PCL and PCL/MMT materials allow the culture of murine L929 fibroblasts on its surface with high viability, very low apoptosis, and without plasma membrane damage, making these materials very adequate for tissue engineering. © 2012 American Chemical Society.MICINN; Comunidad de Madrid (Spain) for financial support (MAT2009-09671 and S2009/MAT 1472); Ramon y Cajal ProgramPeer Reviewe