Empleo de cenizas de fondo de central térmica y cal como filler en mezclas bituminosas

This study focuses on the characterization of bottom ash (PCC-BA) and determining the mechanical characteristics of hot mix asphalt (HMA) using PCC-BA and hydrated lime (HL) as filler. Physical and chemical characterization of the bottom ash was carried out to evaluate its eventual reutilization as filler substitute. The materials tested in this study were made using 0%, 25%, 50%, 70% and 100% of PCC-BA combined with HL. HMA mixes were evaluated in terms of their engineering properties, namely: air voids in the mixes, water sensitivity, stiffness modulus, performance in wheel tracking test and fatigue resistance. The results obtained indicate that HMA mixes with a filler blend of 70% PCC-BA and 30% HL fulfil European standards and are suitable for light traffic or small infrastructures.Este estudio se centra en la caracterización de las cenizas de fondo (PCC-BA) y la determinación de las características mecánicas de mezclas bituminosas en caliente (HMA), utilizando cenizas de fondo y la cal hidratada (HL) como filler. Se realizó la caracterización física y química de las cenizas de fondo para evaluar su empleo como sustituto de filler. Las mezclas ensayadas en este estudio se realizaron utilizando 0%, 25%, 50%, 70% y 100% de cenizas de fondo combinadas con cal hidratada. Se evaluaron propiedades ingenieriles de las mezclas bituminosas, tales como los huecos de aire en las mezclas, la sensibilidad al agua, el módulo de rigidez, el ensayo de pista y la resistencia a la fatiga. Los resultados obtenidos indican que las mezclas bituminosas fabricadas con una combinación de filler del 70% de cenizas de fondo y el 30% cal hidratada, cumplen con las normas europeas y son adecuados para su aplicación con tráficos ligeros o en pequeñas infraestructuras

Estimación de la resistencia a compresión simple del jabre estabilizado “in situ” con cemento como material en la formación de explanadas de carreteras

Granite rock has powerful alterations at several meters of depth. The clayed sand resulting is commonly known as jabre. This “in situ” mixture of cement-stabilized soil requires a laboratory formula. Even when the test section is correctly verified, the mechanical properties of the homogeneous mixture of jabre exhibit high degrees of dispersion. The laboratory work undertaken included particle-size analysis and screening, defini­tion of liquid and plastic limits, compressive strength, dry density and moisture content over stabilized samples, modified Proctor, California Bearing Ratio (CBR) and the determination of the workability of the hydrauli­cally bound mixtures. The stress resistance curve was analyzed by means of a multilinear model of unconfined compressive strength (UCS). Since practical engineering only requires UCS for 7 days, in order to gain greater knowledge of the material, other UCS transformations were used at other curing times such as 7, 14 and 28 days.La roca granítica presenta habitualmente un horizonte de alteración con varios metros de potencia. La arena arcillosa resultante como producto de alteración se deno­mina comúnmente jabre. Aunque la fórmula de trabajo de la estabilización de jabre con cemento se verifique correctamente en tramos de prueba, la estabilización “in situ” del jabre con cemento presenta habitualmente elevadas dispersiones. Entre los ensayos de laboratorio efectuados se encuentran los ensayos de análisis granulo­métrico, límites de Atterberg, resistencia a compresión simple (RCS), la densidad y humedad sobre probetas de suelo estabilizado, Proctor modificado, índice CBR (California Bearing Ratio) y el plazo de trabajabilidad de la mezcla con cemento. La curva de endurecimiento del suelo estabilizado fue ajustada mediante un modelo multi­lineal. Aunque tradicionalmente se especifique la RCS a 7 días, buscando definir un mejor comportamiento del material, los autores calcularon otros modelos de jabre estabilizado para roturas a 7, 14 y 28 días

People-centered smart cities: an exploratory action research on the Cities’ Coalition for Digital Rights

Declarations and manifestos have emerged across the world claiming to protect citizens’ digital rights. Data-driven technologies in global cities not only have yielded techno-euphoria but also have intensified techno-political concerns as reflected in UN-Habitat’s flagship program called “People-Centered Smart Cities” (PCSC) that advocates the willingness to promote inclusiveness while subverting the technocratic smart city meaning. Against this backdrop, in 2018, the city councils of Barcelona, Amsterdam, and New York formed the Cities’ Coalition for Digital Rights (CCDR), an international network of cities—currently encompassing 49 cities—to promote globally citizens’ digital rights. This article explores what “the right to have digital rights” may currently mean through action research to examine six digital rights-related factors. Full findings revealed not only distinct strategies—related to AI adoption—but also common policy patterns in the 13 CCDR cities

Adsorció de l'herbicida Paraquat en Alginat de Calci

La sostenibilitat de l’ús de l’aigua esta lligada de forma fonamental al seu ús en l’agricultura. L’activitat agrària afecta directament la qualitat de les aigües. Els residus de fertilitzants i de productes fitosanitaris, entre ells els herbicides, constitueixen una font de contaminació del sòl, els quals a través de processos d’escorrentia i infiltració alteren la qualitat de diferents masses d’aigua. La detecció de residus d’herbicides i els seus metabòlits en les aigües dels rius i el mar fa que la eliminació d’aquets productes orgànics, molts d’ells tòxics, s’hagi convertit en un dels problemes mediambientals més importants. Per tal de intentar solucionar aquest problema s’han realitzat nombrosos estudis sobre la eliminació d’aquests compostos mitjançant diferents processos, essent uns del més utilitzats el procés d’adsorció. En les últimes dècades, la utilització de biopolímers com adsorbents per la eliminació de compostos orgànics de les aigües residuals ha demostrat ser eficaç [1]. En aquest treball es presenta l’estudi sobre l’adsorció de l’herbicida paraquat en l’alginat de calci, així com l’efecte de la presencia del colorant reactive black 5 (RB5) sobre l’adsorció del paraquat. Hem de tenir en compte que les formulacions comercials contenen a més del propi herbicida altres substancies com els colorants que eviten la confusió amb altres tipus de begudes. El paraquat és altament tòxic i pel fet de estar carregat positivament s’uneix fortament a les argiles del sòl, al humus i altres compostos orgànics que poden estar presents en el sòl, però no s’adsorbeix en terres sorrenques amb baix contingut de matèria orgànica. En aquest últim cas el paraquat pot esser alliberat passant a les aigües circumdants al terreny on s’ha aplicat, per escorrentia o infiltració [2]. Les variables que s’han tingut en compte en l’estudi de la capacitat d’adsorció del paraquat en alginat de calci són: el pH, la concentració inicial de paraquat; la velocitat d’agitació; massa d’adsorbent i la concentració de colorant present en la dissolució. Els resultats obtinguts ens han demostrat que l’alginat de calci és eficaç en l’eliminació del paraquat de les dissolucions aquoses. L’adsorció del paraquat es veu influenciada per el pH. Al augmentar el pH augmenta la capacitat d’adsorció del paraquat. La presència de colorant disminueix l’adsorció del paraquat, conservant-se una reducció del 20 i 24% quan s’addicionen 50 i 100 mg/L, respectivament. En aquest estudi també s’ha realitzat un tractament estadístic dels resultats experimentals, aplicant la tècnica de mínims quadrats parcials (PLS; Partial Least Square) [3-5]. La regressió per mínims quadrats parcials (PLS, Partial Least Squares) fa ser introduïda per Herman Wold (1975) per a ser aplicada a ciències econòmiques i socials, tot i que desprès ha estat aplicada a moltes altres branques científiques. La metodologia PLS generalitza i combina característiques de l’Anàlisi de Components Principals (PCA) i l’Anàlisi de Regressió Múltiple. L’anàlisi PLS és utilitzat quan volem correlacionar un elevat nombre de descriptors (variables independents), amb un determinat nombre de variables dependents. Els càlculs s’han realitzat amb el programa SIMPCA-P [6], fent possible la valoració de la capacitat d’adsorció, la predicció toxicològica i l’impacta ambiental en processos similars.Peer Reviewe

Study of the mechanical behavior of asphalt mixtures using fractional rheology to model their viscoelasticity

This study focuses on the mechanical behavior of asphalt mixtures composed of aggregate particles attached with an asphalt binder. Asphalt mixtures are viscoelastic composite materials widely used in the construction of pavement layers. The modelling of such materials is currently done using the Burgers model. However, this model is limited when explaining some of the viscoelastic phenomena of an asphalt mixture, mainly because the Burgers model was developed for a single material with a dual nature. This work presents a new approach that provides a more appropriate framework for studying asphalt mixtures. The model assumes an aggregate particle enclosed by an asphalt material. Viscoelastic equations were developed using derivatives of fractional order. Then, the creep, recovery, and relaxation phenomena in an asphalt mixture were analyzed using the new model. Unlike the Burgers model, the new model can predict the elastic jump observed at the beginning of the creep modulus. Thus, the new model seems to describe better those practical cases of asphalt mixtures used in the construction of pavement layers. The new model can be used to modify the properties of the binder for designing optimized and more resistant asphalt mixtures

Spark plasma versus conventional sintering in the electrical properties of Nasicon-type materials

Li_(1+x)M_(x)Ti_(2−x)(PO_(4))_(3) powders with x = 0 and 0.3 and M = Al, Cr and Fe have been sintered by conventional sintering (CS) and Spark Plasma Sintering (SPS), and the electrical properties have been compared. The use of SPS allows preparing samples with higher density at lower temperature and shorter time than the CS, avoiding segregation of secondary phases and with reduced crystallite size. The introduction of aluminum, chromium and iron in the LiTi_(2)(PO_(4))_(3) (LTP) clearly enhances ionic conductivity even if the samples have similar densities. Despite the different level of density reached with CS and SPS, the activation energies of dc and grain boundary contributions are very similar and the differences in ionic conductivity are determined by pre-exponential factors. The samples produced by SPS showed a well-defined grain boundary meaning a more homogenous electrical contact

Kinetics of antibodies in sera, saliva, and urine samples from adult patients with primary or secondary dengue 3 virus infections

SummaryObjectivesThe kinetics of three serological markers (IgM, IgA, and IgG) in serum, saliva, and urine samples from adult patients with primary or secondary dengue infection were studied.DesignSerum, saliva, and urine samples were collected from 22 patients with clinical and confirmed dengue 3 virus infection during the outbreak in Havana City in 2001. They were tested by capture IgM (MAC-ELISA), IgA (AAC-ELISA), and IgE (EAC-ELISA) and IgG ELISA inhibition method (EIM) to detect specific dengue antibodies.ResultsSimilar kinetics were observed in IgM, IgA, and IgG antibodies in saliva and IgA and IgG in urine samples from secondary cases compared with kinetics in serum samples, although the values were lower. No IgG antibody was detected in saliva and urine samples in primary cases and IgM antibody was not detected in urine samples from either primary or secondary infection. All secondary cases were positive for IgG in saliva and urine samples at day 7. The kinetics of specific IgE antibodies in primary and secondary cases were different.ConclusionsThe kinetics of three serological markers (IgM, IgA, and IgG) in serum, saliva, and urine samples from adult patients with primary or secondary dengue 3 virus infection were studied for the first time, showing its behavior and usefulness in dengue virus diagnosis. The specific IgE could play a role as a serological marker in secondary infections

Straightforward purification method for the determination of the activity of glucose oxidase and catalase in honey by extracting polyphenols with a film-shaped polymer

Glucose oxidase (GOX) and catalase (CAT) regulate the amount of H2O2 in honey, by generating or consuming it, so they are related to the antibacterial and antioxidant activity of honey. However, their activities are hardly analysed, since the process requires a previous dialysis that is non-selective, very time-consuming (>24 h), eco-unfriendly (>6L of buffer) and expensive. This research shows the design and performance of a material that selectively removes the actual interferents. The film-shaped-polymer is immersed for 90́ within a honey solution (12.5 mL of buffer), where it interacts exclusively with 1,2-dihydroxybenzenes, which we proved to be the real interferents (the material contains motifs derived from phenylboronic acid to interact with 1,2-diols). Polymeric chains favour condensation to occur exclusively with 1,2-dihydroxybenzenes, excluding monosaccharides. The interferents’ removal using our designed polymer is selective, low cost (1.42€ per test), rapid and eco-friendly (saves 6L of buffer and 20.5 h of experimental workout per sample).We gratefully acknowledge the financial support provided by all funders. Author Jose Miguel García received grant PID2020-113264RB-I00 / AEI / 10.13039/501100011033 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. Ana Arnaiz received funding from Ministerio de Universidades-European Union in the frame of NextGenerationEU RD 289/2021 (Universidad Politécnica de Madrid). We also gratefully acknowledge European Regional Development Fund (ERDF). Gianluca Utzeri thanks Fundação para a Ciência e a Tecnologia (FCT, Portugal) for PhD grant (SFR/BD/146358/2019). The Coimbra Chemistry Centre is supported by the FCT, through Projects UIDB/00313/2020 and UIDP/00313/2020. To all the beekeepers who provided a sample of honey for this study

Inducible Nitric Oxide Synthase in Heart Tissue and Nitric Oxide in Serum of Trypanosoma cruzi-Infected Rhesus Monkeys: Association with Heart Injury

Chagas disease, a neglected tropical disease caused by the protozoan Trypanosoma cruzi, afflicts from 8 to 15 million people in the Latin America. Chronic chagasic cardiomyopathy (CCC) is the most frequent manifestation of Chagas disease. Currently, patient management only mitigates CCC symptoms. The pathogenic factors leading to CCC remain unknown; therefore their comprehension may contribute to develop more efficient therapies. In patients, high nitric oxide (NO) levels have been associated with CCC severity. In T. cruzi-infected mice, NO, mainly produced via inducible nitric oxide synthase (iNOS/NOS2), is proposed to work in parasite control. However, the participation of iNOS/NOS2 and NO in T. cruzi control and heart injury has been questioned. Here, infected rhesus monkeys and iNOS/NOS2-deficient mice were used to explore the participation of iNOS/NOS2-derived NO in heart injury in T. cruzi infection. Chronically infected monkeys presented electrical abnormalities, myocarditis and fibrosis, resembling the spectrum of human CCC. Moreover, cardiomyocyte lesion correlated with iNOS/NOS2+ cells infiltrating the cardiac tissue. Our findings support that parasite-driven iNOS/NOS2+ cells accumulation in the cardiac tissue and NO overproduction contribute to cardiomyopathy severity, mainly disturbing the pathway involved in electrical synchrony in T. cruzi infection