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Size effect of steel fiber–reinforced concrete cylinders under compressive fatigue loading: Influence of the mesostructure
Get PDFThis study deals with the influence of the fiber concrete mesostructure on the size effect under compressive
fatigue loading. For this purpose, three series of cylindrical specimens of steel fiber–reinforced concrete were
fabricated. Before fatigue testing, all the cylinders were scanned and the main morphological, orientation, and
distribution parameters of the pores and fibers were checked. The images reveal that, near the cylinders’ walls,
the porosity is lower than that in the cores and is even lower for large sizes. Additionally, larger specimens are
more vulnerable to compressive fatigue loading, resulting in a reduction in fatigue life.The authors are grateful for the financial support from the Ministerio de Economía y Competitividad, Spain with grant nos. PID2019-110928RBC32, PID2019–110928RB–C31, and RTC–2017–6736–3, and from the Junta de Comunidades de Castilla-La Mancha, Spain through grant no. SBPLY/19/180501/000220
Study of subcritical water scale-up from laboratory to pilot system for brewer’s spent grain valorization
No full textThe feasibility of an industrial-scale subcritical water (SW) system by scaling up from laboratory to pilot scale in
a discontinuous operation mode has been investigated regarding the valorization of brewer´s spent grain (BSG).
The subcritical water treatment (SWT) of BSG at the pilot scale in a discontinuous mode at 170 ◦C and 22 min,
resulted in the release of 56% of the total carbohydrates present in the BSG. A total pentose yield of 78% was
achieved (18% as monomer and 82% as oligomer). The concentration of inhibitors in the hydrolysate was
relatively low, 0.22 g/L, 0.31 g/L, and 0.13 g/L of furfural and acetic and formic acids respectively. Other highvalue compounds were obtained, such as 6.5 g peptides/L (64% protein yield), 21 mg free amino acids/g protein
(2.17% aa yield), and a total phenolic content (TPC) of 17.84 mg GAE/g dry BSG. In general, the results showed
good reproducibility when scaling up from laboratory to pilot SW process. Good reproducibility of the scale-up
was found for the release yield of arabinoxylo-oligomers, and gluco-oligomers from BSG, also for the protein
yield and the release of free amino acids. However, the xylo-oligomers yield was 13% higher at the lab scale than
at the pilot scale and higher concentrations of monomers and phenolic compounds were found in the SW hydrolysates obtained at the lab scale. Differences in the preheating time in both systems seem to have an effect on
the hydrolysis yield of some the biopolymers. SWT modified the composition of the residual solid, as a decrease
in the concentration of hemicellulose and an increase in the glucan content was observed, which may enhance
the digestibility of the solid improving a further enzymatic release of glucose from the remaining solid.This work was supported by the Agencia Estatal de Investigacion, ´ Spain, [grant numbers PID2019–104950RB-I00 / AEI / 10.13039/ 501100011033, TED2021–129311B-I00 and PDC2022–133443-I00] and the Junta de Castilla y Leon ´ (JCyL), Spain and the European Regional Development Fund (ERDF) [grant number BU050P20]. E. Trigueros and P. Alonso-Riano ˜ predoctoral contracts are funded by JCyL and the European Social Fund (ESF) [ORDEN EDU/574/2018 and EDU/ 556/2019 respectively]
An adjusted analytical solution for thermal design in artificial ground freezing
Get PDFArtificial ground freezing is a widely used, reliable method for excavation in water-bearing ground. The questions posed in the thermal design of ground freezing projects require solving moving boundary (Stefan) problems. Approximate analytical solutions, such as the ones by St¨
ander1 and Sanger and Sayles,2 have been
developed for thermal engineering design and are used by practitioners across the industry. For instance, Sanger
& Sayles’ solution is widely used for the single-freeze-pipe problem, but it has proven to be of limited accuracy.3
In the present paper, an adjustment to this formula is proposed based on the re-evaluation of their empirical
assumption that the ratio between the temperature penetration depth and the phase-change radius equals a
constant value of 3 regardless the conditions. A sensitivity study is performed using a verified numerical model as
a benchmark to study several problems with different initial and boundary conditions (initial, phase change and
freeze pipe temperatures) and thermal properties of the ground (water content, thermal conductivity and heat
capacity). This is done for the freezing times of 10 and 365 days, in order to consider the potential change of the
ratio with the freezing time. In this way, a calibrated formula is proposed to find appropriate values of this ratio
and a suitable adjustment to Sanger & Sayles’ solution is determined. Adjusting Sanger & Sayles’ solution in this
manner, a significantly higher and more consistent accuracy is achieved for different boundary and initial
conditions. This accuracy improvement was checked for real conditions from an engineering project, which
shows that the adjustment can be useful for thermal problems in engineering design of ground freezing
Guía didáctica para promover el Comercio Justo y el Consumo Responsable en centros de Educación Primaria
No full textCon esta guía didáctica, de carácter marcadamente práctico, la Universidad de Burgos refuerza su compromiso por la Sostenibilidad y el Desarrollo Humano Sostenible, recogidos en sus estatutos y en la Declaración Institucional de la UBU a favor del Comercio Justo y el Consumo Responsable. Esta Guía Didáctica tiene como objetivo, impulsar la integración del comercio justo y el consumo responsable en el trabajo, la formación y la sensibilización en centros educativos de Educación Primaria, así como en otros Centros o Asociaciones que trabajan con colectivos vulnerables o en Centros de Educación Especial. El documento recoge una serie de actividades y talleres, todos ellos de carácter práctico, con el fin de servir de recurso didáctico para el profesorado de centros educativos en etapa escolar. Los talleres son adaptables a los distintos cursos de la etapa de Educación Primaria Obligatoria, y a otros colectivos o ciclos educativos
Generation of a high yield vaccine backbone for influenza B virus in embryonated chicken eggs
No full textInfluenza B virus (IBV) strains are one of the components of seasonal influenza vaccines in both trivalent and quadrivalent formulations. The vast majority of these vaccines are produced in embryonated chickens’ eggs. While optimized backbones for vaccine production in eggs exist and are in use for influenza A viruses, no such backbones exist for IBVs, resulting in unpredictable production yields. To generate an optimal vaccine seed virus backbone, we have compiled a panel of 71 IBV strains from 1940 to present day, representing the known temporal and genetic variability of IBV circulating in humans. This panel contains strains from the B/Victoria/2/87-like lineage, B/Yamagata/16/88-like lineage and the ancestral lineage that preceded their split to provide a diverse set that would help to identify a suitable backbone which can be used in combination with hemagglutinin (HA) and neuraminidase (NA) glycoproteins from any IBV strain to be incorporated into the seasonal vaccine. We have characterized and ranked the growth profiles of the 71 IBV strains and the best performing strains were used for co-infection of eggs, followed by serial passaging to select for high-growth reassortant viruses. After serial passaging, we selected 10 clonal isolates based on their growth profiles assessed by hemagglutination and plaque-forming units. We then generated reverse genetics systems for the three clones that performed best in growth curves. The selected backbones were then used to generate different reassortant viruses with HA/NA combinations from high and low titer yielding wild type IBV. When the growth profiles of the recombinant reassortant viruses were tested, the low titer yielding HA/NA viruses with the selected backbones yielded higher titers similar to those from high titer yielding HA/NA combinations. The use of these IBV backbones with improved replication in eggs might increase yields for the influenza B virus components of seasonal influenza virus vaccines.This study was partly funded by the Center for Research for Pathogenesis and Transmission (CRIPT), a NIAID supported Center of Excellence for Influenza Research and Response (CEIRR, contract # 75N93021C00014), and SEM-CIVIC, a NIAID supported Collaborative Influenza Vaccine Innovation Center (contract # 75N93019C00051) to AG-S
Analysis of a scheme which preserves the dissipation and positivity of Gibbs' energy for a nonlinear parabolic equation with variable diffusion
No full textIn this work, we design and analyze a discrete model to approximate the solutions of a parabolic partial differential equation in multiple dimensions. The mathematical model considers a nonlinear reaction term and a space-dependent diffusion coefficient. The system has a Gibbs' free energy, we establish rigorously that it is non-negative under suitable conditions, and that it is dissipated with respect to time. The discrete model proposed in this work has also a discrete form of the Gibbs' free energy. Using a fixed-point theorem, we prove the existence of solutions for the numerical model under suitable assumptions on the regularity of the component functions. We prove that the scheme preserves the positivity and the dissipation of the discrete Gibbs' free energy. We establish theoretically that the discrete model is a second-order consistent scheme. We prove the stability of the method along with its quadratic convergence. Some simulations illustrating the capability of the scheme to preserve the dissipation of Gibb's energy are presented.The corresponding author (J.E.M.-D.) wishes to acknowledge the financial support from the National Council for Science and Technology of Mexico (CONACYT) through grant A1-S-45928
Conexión intergeneracional sobre los prejuicios y los estereotipos de género
Get PDFLa personalidad de cada ser humano es única. Los agentes que influyen en ella son una
fuente clave para la adquisición de unos valores éticos y morales. En el presente estudio
se analiza las actitudes hacia la igualdad de género entre progenitores y descendientes y,
posteriormente, se conoce qué tipo de conexión se establece entre ambas generaciones
sobre los estereotipos de género. La metodología utilizada ha sido mixta compuesta por
dos tipos de análisis: cuantitativo y cualitativo. El primero de ellos a través de una
encuesta titulada “Cuestionario de Actitudes hacia la Igualdad de Género (CAIG)”, la
cual se ha analizado a través del programa estadístico SPSS obteniendo algunas
conexiones en algunos ámbitos, pero no en su totalidad. Por otro lado, la segunda
herramienta ha sido una entrevista en profundidad, examinada con el software Atlas.ti 9.
Las personas entrevistadas han sido una madre y su hija, quienes han demostrado sus
testimonios sobre los estereotipos de género. Esta investigación concluye que, entre la
progenitora y su descendiente, existe poca influencia y aboga más por el dominio de los
sectores externos y del “propio yo” como principal agente influenciador