A micro-macro homogenization for modeling the masonry out-of-plane response

This study introduces a finite element model based on a two-scale beam-to-beam homogenization procedure for the analysis of masonry structural members undergoing prevailing axial and bending stress states. The model is developed considering the periodic repetition of bricks and mortar joints in regular stack bond arrangement and assuming a linear elastic behavior for the former and a nonlinear response for the latter. At the microscopic heterogeneous scale, the behavior of a Unit Cell (UC) made of a single brick and mortar layer is described through an equivalent Timoshenko beam representation, where a nonlocal damage formulation with friction plasticity governs the mortar nonlinear constitutive relationship. Basing on a semi-analytical approach, the microscopic quantities are, then, homogenized to define an equivalent beam model at the macroscopic scale. The proposed finite element model is implemented in standard numerical codes to investigate the response of typical one-dimensional (1D) masonry elements. This study shows the numerical simulation of two experimental tests: a rectangular wallette under out-of-plane bending and a circular arch under vertical forces. The results obtained for the proposed model are compared with those resulting from micromechanical approaches and the experimental outcomes

Multiscale analysis of masonry vaults coupling shell elements to 3D-Cauchy continuum

This study adopts an enhanced multiscale approach to investigate the effects of the damaging process on the structural behavior of masonry vaults with regular texture, in view of their safety assessment. The model, recently developed by the authors, links two different structural models at macro and microscale, exploiting the advantages of each formulation. At the macroscopic level a homogeneous Mindlin-Reissner shell is modeled and its constitutive response is derived by the detailed analysis of a three-dimensional (3D) masonry Unit Cell (UC) studied at microlevel. The UC is considered as the assembly of elastic bricks and damage-plastic zerothickness interfaces, representative of both mortar and mortar-unit interaction, thus accounting for the actual geometry, arrangement and constitutive response of each constituent material. A Transformation Field Analysis procedure is used to link the two scales, speeding up the numerical simulations. Structural response of a masonry vault under differential settlements is investigated, determining its load-bearing capacity and the damaging path evolving in the structure up to collapse. The reliability of the results is proved by comparison with outcomes derived by detailed micromechanical analysis, interpreting and arguing similarities and differences. © 2023, Association of American Publishers. All rights reserved

Multiscale Finite Element Modeling Linking Shell Elements to 3D Continuum

The present paper investigates the response of masonry structural elements with periodic texture adopting an advanced multiscale finite element model, coupling different formualations at the two selected scales of analysis. At the macroscopic structural level, a homogeneous thick shell is considered and its constitutive response is derived by the detailed analysis of the masonry repetitive Unit Cell (UC), analyzed at the microlevel in the framework of the three-dimensional (3D) Cauchy continuum. The UC is formed by the assembly of elastic bricks and nonlinear mortar joints, modeled as zero-thickness interfaces. The Transformation Field Analysis procedure is invoked to address the nonlinear homogenization problem of the regular masonry. The performance of the model in reproducing various masonry textures is explored by referring to an experimentally tested pointed vault under different profiles of prescribed differential settlements. The structural behavior of the vault is studied in terms of global load-displacement curves and damaging patterns and the numerical results are compared with those recovered by detailed micromechanical analyses and experimental evidences

Multiscale finite element modeling linking shell elements to 3D continuum

The present paper investigates the response of masonry structural elements with periodic texture adopting an advanced multiscale finite element model, coupling different formulations at the two selected scales of analysis. At the macroscopic structural level, a homogeneous thick shell is considered and its constitutive response is derived by the detailed analysis of the masonry repetitive Unit Cell (UC), analyzed at the microlevel in the framework of the threedimensional (3D) Cauchy continuum. The UC is formed by the assembly of elastic bricks and nonlinear mortar joints, modeled as zero-thickness interfaces. The Transformation Field Analysis procedure is invoked to address the nonlinear homogenization problem of the regular masonry. The performance of the model in reproducing various masonry textures is explored by referring to an experimentally tested pointed vault under different profiles of prescribed differential settlements. The structural behavior of the vault is studied in terms of global load-displacement curves and damaging patterns and the numerical results are compared with those recovered by detailed micromechanical analyses and experimental evidences

Facilely synthesized nitrogen-doped reduced graphene oxide functionalized and/or co-doped with metal ions as electrocatalyst for oxygen reduction reaction

Due to fossil fuels depletion and environmental pollution, clean and sustainable energy technologies, e.g. fuel cells and metal-air batteries, have attracted extensive attention. To push further the research on these electrochemical devices, low-cost, durable and efficient electrocatalysts alternative to platinum are required, to boost the oxygen reduction reaction (ORR). A microwave-assisted method has been optimized, to obtain effective heterogeneous catalyst for ORR, starting from graphene oxide (GO), urea and a transition metal (e.g. Mn and Cu) precursor. We have proved that our synthetic method originates porphyrin-like structures containing pyrrole rings within the reduced GO (rGO) basal plane which coordinate the Mn2+. In the case of copper, however, Cu2+ forms an ionic tetra coordinated structure anchored at the rGO surface via residual oxygen containing functional groups. In both cases, metal complex acts as an ORR highly efficient catalytic reaction center and their identification were strongly supported by several characterization techniques, such as X-ray Photoelectron Spectroscopy (XPS), X-ray absorption spectroscopies (XAS) and Transmission Electron Microscopy (TEM), together with Density Functional Theory (DFT) simulations. All synthesized materials exhibit outstanding catalytic properties toward ORR, as evidenced by electron transfer numbers larger than 3.8 and peroxide percentages lower than 7%, similar to Pt/C reference electrode

Facilely synthesized nitrogen-doped reduced graphene oxide functionalized with copper ions as electrocatalyst for oxygen reduction

Nitrogen-doped reduced graphene oxide is successfully synthesized and functionalized with hydroxylated copper ions via one-pot microwave-assisted route. The presence of cationic Cu coordinated to the graphene layer is fully elucidated through a set of experimental characterizations and theoretical calculations. Thanks to the presence of these hydroxyl-coordinated Cu2+ active sites, the proposed material shows good electrocatalytic performance for the oxygen reduction reaction, as evidenced by an electron transfer number of almost 4 and by high onset and half-wave potentials of 0.91 V and 0.78 V vs. the reversible hydrogen electrode, respectively. In addition, the N-doped Cu-functionalized graphene displays a superior current retention with respect to a commercial Pt/C catalyst during the stability test, implying its potential implementation in high-performance fuel cells and metal-air batteries

Intermittent docetaxel chemotherapy as first-line treatment for metastatic castration-resistant prostate cancer patients

Aims: The intermittent administration of chemotherapy is a means of preserving patients' quality of life (QL). The aim of this study was to verify whether the intermittent administration of docetaxel (DOC) improves the patients' QL. Patients & methods: All patients received DOC 70 mg/m every 3 weeks for eight cycles. The patients were randomized to receive DOC continuously or with a fixed 3-month interval after the first four DOC courses. Results: The study involved 148 patients. There was no difference in QL between the groups receiving intermittent or continuous treatment. Intermittence had no detrimental effects on disease control. Conclusion: Although feasible and not detrimental, our results showed that true intermittent chemotherapy in metastatic castration-resistant prostate cancer patients failed to improve the patients' QL

Post-bronchoscopy fatal endobronchial hemorrhage in a woman with bronchopulmonary mucormycosis: a case report

<p>Abstract</p> <p>Introduction</p> <p>During infection, Mucorales fungi invade major blood vessels, leading to extensive necrosis, and in cases of extensive pulmonary disease, bleeding into the lungs may occur.</p> <p>Case presentation</p> <p>We report an unexpected event of post-bronchoscopy fatal endobronchial hemorrhage in a 62-year-old HIV-negative Italian woman with well controlled diabetes mellitus who presented with diffuse cavitated pulmonary lesions. Fiberoptic bronchoscopy revealed bilateral obstruction of the segmental bronchi. Fatal massive bleeding occurred after standard biopsy procedures. Histologic examination showed that the hyphae were more deeply colored by hematoxylin-eosin (H&E) than by other stains for fungi. Culture and autopsy confirmed bronchopulmonary mucormycosis.</p> <p>Conclusion</p> <p>Infection by Mucorales fungi should be considered in the diabetes population regardless of the degree of metabolic control. In these patients, particular caution should be taken during bronchoscopic procedures because of the greater friability of the fungal lesions.</p