Toward validation of simulated accelerograms via prediction equations for nonlinear SDOF response

Seismic structural risk analysis of critical facilities may require nonlinear dynamic analysis for which record selection is one of the key issues. Notwithstanding the increasing availability of database of strong-motion records, it may be hard to find accelerograms that fit a specific scenario (e.g., in terms of magnitude and distance) resulting from hazard assessment at the site of interest. A possible, alternative, approach can be the use of artificial and/or simulated ground motion in lieu of real records. Their employment requires systematic engineering validation in terms of structural response and/or seismic risk. Prediction equations for peak and cyclic inelastic single degree of freedom systems’ response, based on Italian accelerometric data, are discussed in this study as a possible benchmark, alongside real record counterparts, for the validation of synthetic records. Even if multiple events would be in principle required, an extremely preliminary validation is carried out considering only four simulated records of the 1980 Irpinia (southern Italy) M w 6.9 earthquake. Simulated records are obtained through a broadband hybrid integral-composite technique. Results show how this simulation method may lead to generally acceptable results. It is also emphasized how this kind of validation may provide additional results with respect to classical signal-to-signal comparison of real and simulated records

Damage tolerance of bio-inspired helicoidal composites under low velocity impact

It is well known that laminated composite materials are prone to impact damage caused by foreign objects and exhibit poor damage resistance in through the thickness direction. By drawing inspiration from naturally occurring impact resistant structures, such as dactyl clubs of mantis shrimp, enhanced damage tolerance and impact energy absorption can be achieved with traditional CFRP layers by creatively arranging them into bio-inspired configurations, called helicoidal or Bouligand structures. Through an extensive numerical analyses of low velocity impact (LVI) supported by the experimental results, a further insight into the possibilities that these structures can offer in terms of damage resistance was attained. By comparing the results of three square plates with different planar sizes, it was shown that the helicoidal layups are more effective at absorbing energy while minimising through the thickness failure than standard quasi-isotropic and cross-ply laminates. Although the helicoidal composites generally exhibited a higher degree of delamination in LVI tests, the standard lamination schemes displayed higher degree of perforation, which resulted in a reduced residual strength in the compression after impact (CAI) testing of a quasi-isotropic laminate compared to several helicoidal ones subjected to 40 J and 80 J impact energy. Furthermore, using advanced finite element analysis (FEA) code LS-DYNA® for simulating LVI and CAI events, it was revealed that the helicoidal arrangement endured the least amount of fibre damage.</p

"bisphenol a: An emerging threat to male fertility"

Background: Among the factors causing male infertility, one of the most debated is the exposure to environmental contaminants. Recently, the chemical compound Bisphenol A (BPA) has drawn attention from the reproductive science community, due to its ubiquitous presence in day-to-day life. Its toxic action appears to mainly affect the male reproductive system, directly impacting male fertility. Main: The purpose of this review is to investigate current research data on BPA, providing an overview of the findings obtained from studies in animal and human models, as well as on its supposed mechanisms of action. Conclusion: A clear understanding of BPA action mechanisms, as well as the presumed risks deriving from its exposure, is becoming crucial to preserve male fertility. The development and validation of methodologies to detect BPA toxic effects on reproductive organs can provide greater awareness of the potential threat that this chemical represents

Versatile and non-cytotoxic GelMA-xanthan gum biomaterial ink for extrusion-based 3D bioprinting

Extrusion-based 3D bioprinting allows the 3D printing of bioinks, composed of cells and biomaterials, to mimic the complex 3D hierarchical structure of native tissues. Successful 3D bioprinting requires bioinks with specific properties, such as biocompatibility, printability, and biodegradability according to the desired application. In the present work, we aimed at developing a new versatile blend of gelatin methacryloyl-xanthan gum (GelMA-XG) suitable for extrusion-based 3D bioprinting with a straightforward process. To this end, we first optimized the process of gelatin methacryloyl (GelMA) synthesis by investigating the impact of different buffer solutions on the degree of functionalization, swelling degree, and degradation rate. The addition of xanthan gum (XG) enabled further tuning of biodegradability and an improvement of GelMA printability. Specifically, an optimal concentration of XG was found through rheological characterization and printability tests. The optimized blend showed enhanced printability and improved shape fidelity as well as its degradation products turned out to be non-cytotoxic, thus laying the foundation for cell-based applications. In conclusion, our newly developed biomaterial ink is a promising candidate for extrusion-based 3D bioprinting

Clues of wildfire-induced geotechnical changes in volcanic soils affected by post-fire slope instabilities

Wildfires can significantly affect mountain hillslopes through the combustion of trees and shrubs and changes in soil properties. The type and magnitude of the associated post-fire effects depend on several factors, including fire severity and soil physical-mechanical-hydraulic features that, coupled with climate and topographic conditions, may cause increased runoff, erosion, and slope instability as consequence of intense rainfall. The post-fire response of slopes is highly site-specific. Therefore, in situ surveys and laboratory tests are needed to quantify changes in key soil parameters. The present study documents the post-fire physical and hydromechanical properties of pyroclastic topsoil collected from three test sites that suffered wildfires and rainfall-induced post-fire events in 2019 and 2020 in the Sarno Mountains (Campania Region, southern Italy). The tested pyroclastic soils in burned conditions show (i) no significant changes in grain size distribution, soil organic matter, and specific gravity; (ii) a deterioration in shear strength in terms of decreased soil cohesion caused by the fire-induced weakening of root systems; and (iii) a decrease in hydraulic conductivity. Accordingly, it can be argued that the documented post-fire erosion responses were mainly caused by the reduced cohesion and hydraulic conductivity of the burned topsoil layer, as well as by the loss of vegetation cover and the deposition of fire residues. Although deserving further deepening, this study can represent the necessary background for understanding the initiation mechanism of post-fire erosion processes in the analyzed area and on several natural slopes under similar conditions

Aerosol Jet Printing of a Benzocyclobutene-Based Ink as Adhesive Material for Wafer Bonding Application

Aerosol jet printing (AJP) is an emerging additive manufacturing technology that is gaining increasing attention in the electronic field. Several studies have been carried out on the AJP of conductive, semiconductive, and dielectric polymers for electronic applications. However, wafer bonding is an application that is still uncovered by literature. Therefore, in this work, the AJP of benzocyclobutene (BCB) as a polymeric adhesive for wafer bonding is presented for the first time. A thorough characterization of the processing parameters is carried out to identify the most ideal conditions for printing at a relatively high speed. Then, square patterns are printed, proving the versatility of the AJP technology in terms of the reachable thickness of the deposited BCB patterns. Complex patterns with a resolution of approximate to 60 mu m are also printed. The bonding properties of the BCB are characterized from a morphological and mechanical point of view. In particular, the shear strength of the BCB coatings deposited with AJP is approximate to 39 MPa and it is comparable with the shear strength of BCB coating deposited by spin-coating. Consequently, AJP represents a valid alternative for the deposition of polymeric adhesive for wafer bonding

WATER\u2013BUDGET AS A TOOL TO EVALUATE THE SUSTAINABLE USE OF GROUNDWATER RESOURCES (ISONZO PLAIN, NE ITALY)

Water budget, hydrogeology, Soča/Isonzo River, climate chang

Corevalve vs. Sapien 3 transcatheter aortic valve replacement: A finite element analysis study

Aim: to investigate the factors implied in the development of postoperative complications in both self-expandable and balloon-expandable transcatheter heart valves by means of finite element analysis (FEA). Materials and methods: FEA was integrated into CT scans to investigate two cases of postoperative device failure for valve thrombosis after the successful implantation of a CoreValve and a Sapien 3 valve. Data were then compared with two patients who had undergone uncomplicated transcatheter heart valve replacement (TAVR) with the same types of valves. Results: Computational biomechanical modeling showed calcifications persisting after device expansion, not visible on the CT scan. These calcifications determined geometrical distortion and elliptical deformation of the valve predisposing to hemodynamic disturbances and potential thrombosis. Increased regional stress was also identified in correspondence to the areas of distortion with the associated paravalvular leak. Conclusion: the use of FEA as an adjunct to preoperative imaging might assist patient selection and procedure planning as well as help in the detection and prevention of TAVR complications

Teacher Training for Health Promotion and Education in School: an experience report

Este trabalho, desenvolvido por trinta meses em Vargem Grande Paulista-SP, objetivou capacitar professores do Ensino Infantil e Fundamental para desenvolverem o processo de Educação em Saúde, junto a seus alunos. Utilizou-se um questionário com perguntas abertas e fechadas e a técnica de grupo focal, sendo os resultados analisados quali-quantitativamente. Iniciou-se com um diagnóstico situacional, originando os seguintes "temas geradores": Escola Promotora da Saúde, Observação do Escolar, Prevenção de Acidentes, entre outros. Esses possibilitaram a discussão de saúde de forma integral e o estabelecimento da relação desta com o meio ambiente. A segunda etapa se constituiu na avaliação do processo. Como resultados, a capacitação realizada, calcada na idéia de saúde como sinônimo de qualidade de vida, proporcionou aos professores a possibilidade de revisar seus conceitos sobre saúde e educação em saúde, seu papel como agente promotor da saúde e da prevenção de doenças. Verificou-se também que se tornaram capacitados para desenvolver os temas trabalhados de forma transversal.This project, developed during thirty months in Vargem Grande Paulista, state of São Paulo, had the objective of training Primary and Secondary School teachers to develop the Health Education process, together with their students. A questionnaire was used with open and closed questions and a focus group technique, with results being analyzed quali-quantitatively. It began with a situational diagnosis producing "generative themes": Health Promotion School, Observation of School-aged Children, Accident Prevention, among others. These enabled the discussion on health in an integral way and the establishment of the latter's relationship to the environment. The second stage consisted of process evaluation. As a result, the training, carried out based on the idea of health as synonymous with quality of life, provided teachers with the possibility of reviewing their concepts of health and health education, as well as their role as agents of health promotion and illness prevention. It was also seen that they became trained to develop the studied themes in a transversal way