Confinement of FRP concrete columns: Review of design guidelines and comparison with experimental results

A regulatory framework is required to ensure the correct design of Fibre-Reinforced Polymers (FRPs) increasingly being used as an externally-bonded strengthening system on concrete columns. Several design guidelines on the confinement of FRP concrete have been developed over the past few years worldwide, each proposing a different approach, resulting in different predictions. This study aims to evaluate and compare nine international design guidelines used to predict the compressive strength of confined concrete in FRP-strengthened concrete columns and weigh them against experimental results. The results of this investigation reveal that the predictions from the guidelines on the compressive strengthening of FRP-confined concrete are generally suitable for circular columns, with the ACI-440 and CNR-DT 200 guideline predictions being two of the most accurate. Nevertheless, the guidelines generally tend to overestimate the load-carrying capacity for the compressive strength of FRP-confined concrete in non-circular columns, for which further experimental work using large-scale specimens is required

Influence of recycled aggregate quality from precast rejection on mechanical properties of self-compacting concrete

The use of coarse aggregates from crushing pre-existing concrete in the manufacturing of new concrete needs experimental results to validate its influence in the properties of the new concrete elements. In the present study we assessed the impact of using different proportions of replacement up to 100% of natural aggregates with recycled aggregates in the concrete properties; moreover, the effect of pre-treatments of pre-saturation, washing and the aggregates’ source (from precast concrete rejected pieces and construction and demolition waste) was analysed. The best results were obtained with dry and washed recycled aggregates, the compressive strength increment was between the 8 and 17% compared to conventional concrete. Results also pointed out that recycled aggregate that exclusively comes from precast concrete pieces lead to a better concrete mechanical characteristic than the aggregates which origin is construction and demolition waste. In addition, a clear relationship between the percentage of recycled aggregate substitution and the workability and mechanical performance of self-compacting concrete is observed. The results presented in this paper allow to state that precast concrete factories can recycle their rejected elements into recycled coarse aggregates for manufacturing new products, this will allow to protect the environment by reducing the need of raw material consumption and the C&DW landfill

Combined dark matter searches towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS

Cosmological and astrophysical observations suggest that 85% of the total matter of the Universe is made of Dark Matter (DM). However, its nature remains one of the most challenging and fundamental open questions of particle physics. Assuming particle DM, this exotic form of matter cannot consist of Standard Model (SM) particles. Many models have been developed to attempt unraveling the nature of DM such as Weakly Interacting Massive Particles (WIMPs), the most favored particle candidates. WIMP annihilations and decay could produce SM particles which in turn hadronize and decay to give SM secondaries such as high energy \u1d6fe rays. In the framework of indirect DM search, observations of promising targets are used to search for signatures of DM annihilation. Among these, the dwarf spheroidal galaxies (dSphs) are commonly favored owing to their expected high DM content and negligible astrophysical background. In this work, we present the very first combination of 20 dSph observations, performed by the Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS collaborations in order to maximize the sensitivity of DM searches and improve the current results. We use a joint maximum likelihood approach combining each experiment’s individual analysis to derive more constraining upper limits on the WIMP DM self-annihilation cross-section as a function of DM particle mass. We present new DM constraints over the widest mass range ever reported, extending from 5 GeV to 100 TeV thanks to the combination of these five different \u1d6fe-ray instruments

Pro-Myogenic Environment Promoted by the Synergistic Effect of Conductive Polymer Nanocomposites Combined with Extracellular Zinc Ions

[EN] Musculoskeletal tissue can self-regenerate after injury, however, this self-renewal capacity is limited in degenerative diseases or volumetric muscle loss. Tissue engineering strategies involving biomaterials, cells, and bioactive agents have emerged as a tool to regenerate damaged skeletal muscle. The role of biomaterials is not only to provide structural support for tissue regeneration but also to include some biophysical and biochemical cues that enhance cell proliferation and differentiation into different tissues. In this context, electrochemical cues are essential for myofiber motility and myoblast differentiation. Here, we engineered electrically conductive nanocomposites, which will promote bioactivity in the form of intrinsic surface conductivity, close to that of human skeletal muscle tissue. In addition, extracellular zinc ions were incorporated in the cell microenvironment as a myogenic factor. We show that the combination of both approaches acts synergically generating enhanced cell microenvironments that promote myogenesis. Abstract A new strategy based on the combination of electrically conductive polymer nanocomposites and extracellular Zn2+ ions as a myogenic factor was developed to assess its ability to synergically stimulate myogenic cell response. The conductive nanocomposite was prepared with a polymeric matrix and a small amount of graphene (G) nanosheets (0.7% wt/wt) as conductive filler to produce an electrically conductive surface. The nanocomposites¿ surface electrical conductivity presented values in the range of human skeletal muscle tissue. The biological evaluation of the cell environment created by the combination of the conductive surface and extracellular Zn2+ ions showed no cytotoxicity and good cell adhesion (murine C2C12 myoblasts). Amazingly, the combined strategy, cell¿material interface with conductive properties and Zn bioactive ions, was found to have a pronounced synergistic effect on myoblast proliferation and the early stages of differentiation. The ratio of differentiated myoblasts cultured on the conductive nanocomposites with extracellular Zn2+ ions added in the differentiation medium (serum-deprived medium) was enhanced by more than 170% over that of non-conductive surfaces (only the polymeric matrix), and more than 120% over both conductive substrates (without extracellular Zn2+ ions) and non-conductive substrates with extracellular Zn2+. This synergistic effect was also found to increase myotube density, myotube area and diameter, and multinucleated myotube formation. MyoD-1 gene expression was also enhanced, indicating the positive effect in the early stages of myogenic differentiation. These results demonstrate the great potential of this combined strategy, which stands outs for its simplicity and robustness, for skeletal muscle tissue engineering applications.This research was funded by Spanish Ministry of Science and Innovation (MCINN, Agencia Estatal de Investigación/FEDER funds) through the RTI2018-097862-B-C21 (awarded to R.S.S. and J.M-M.) and PID2020-119333RB-I00/AEI/10.13039/501100011033 (awarded to Á.S-A.) projects,x]. CIBER-BBN is an initiative funded by the VI National R & D & I Plan 2008¿2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions were financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund.Aparicio-Collado, JL.; Molina Mateo, J.; Torregrosa Cabanilles, C.; Vidaurre, A.; Salesa, B.; Serrano Aroca, A.; Sabater I Serra, R. (2022). Pro-Myogenic Environment Promoted by the Synergistic Effect of Conductive Polymer Nanocomposites Combined with Extracellular Zinc Ions. Biology. 11(12):1-19. https://doi.org/10.3390/biology11121706119111

The Power Board of the KM3NeT Digital Optical Module: Design, Upgrade, and Production

The KM3NeT Collaboration is building an underwater neutrino observatory at the bottom of the Mediterranean Sea, consisting of two neutrino telescopes, both composed of a three-dimensional array of light detectors, known as digital optical modules. Each digital optical module contains a set of 31 three-inch photomultiplier tubes distributed over the surface of a 0.44 m diameter pressure- resistant glass sphere. The module also includes calibration instruments and electronics for power, readout, and data acquisition. The power board was developed to supply power to all the elements of the digital optical module. The design of the power board began in 2013, and ten prototypes were produced and tested. After an exhaustive validation process in various laboratories within the KM3NeT Collaboration, a mass production batch began, resulting in the construction of over 1200 power boards so far. These boards were integrated in the digital optical modules that have already been produced and deployed, which total 828 as of October 2023. In 2017, an upgrade of the power board, to increase reliability and efficiency, was initiated. The validation of a pre-production series has been completed, and a production batch of 800 upgraded boards is currently underway. This paper describes the design, architecture, upgrade, validation, and production of the power board, including the reliability studies and tests conducted to ensure safe operation at the bottom of the Mediterranean Sea throughout the observatory’s lifespan