Multiscale damage modeling of advanced composite materials

The use of composite materials has spread over the years throughout the engineering areas of structures. The technological progress in this field has recently expanded, resulting in the design of new composite configurations, including multilayered composite materials and multifunctional nanostructured materials. Even though traditional and emerging composite materials offer wide potentialities for engineering, a significant challenge is still open with respect to damage phenomena. Driven by safety requirements and cost-effective optimization needs, damage modeling has gained a fundamental role for composite engineering. It represents a strong motivation to support design procedures by means of numerical methods, such as finite element analyses. Recently, multiscale computational analyses effectively gained a major role within the challenging task of damage prediction. Particularly, by bridging physical phenomena occurring at different scales, i.e. macro, meso, micro and even nano, damage evolution can be accurately predicted. The present work is collocated within this scenario with the aim of exploring and addressing different critical issues related to the failure mechanisms acting at different length scales of different composite systems. The multiscale procedures, proposed to evaluate the damage behavior of such materials, involved experimental, analytical and numerical tools. In detail, damage modeling has been performed for different case studies: i) GFRP composite laminates, ii) phenolic impregnated skins/honeycomb Nomex core sandwich structures, iii) Carbon Nanotube/Nanofiber modified S2-Glass/epoxy composites. For the case study i), the activity concerned the damage occurred in case of low-velocity impact tests, carried out on glass fabric/epoxy laminates. In this case, the multiscale modeling was implemented to account for both intralaminar and interlaminar levels of damage occurring within the composite laminate. This allowed to characterize the critical parameters acting at the smaller (interlaminar) scale which affect the macroscopic impact response of the composite laminate. With reference to honeycomb sandwich structures of case ii), due to their hierarchical structure, a multiscale approach was necessary in order to suitably capture damage mechanisms occurring to the composite skins and honeycomb core. The study was firstly aimed at accurately addressing the out-of-plane compressive response; particularly, in order to evaluate the influence of imperfection variability on the buckling and crushing behavior, a statistics-based approach was proposed and applied to a detailed finite element model of a single representative honeycomb cell. Furthermore, the impact was also investigated. Finite element numerical models, based on the sandwich assembly structure, were progressively validated through experimental tests, both static and dynamic, performed from the coupon to the sandwich assembly length scale. In the case study iii) the multiscale damage modeling procedure was focused on some issues related to the Carbon Nanotube/Nanofiber length scale, including nanotube length and orientation characterization, stress transfer to the matrix and nanotube toughening mechanisms. A micromechanical model, taking into account CNT length and orientation distribution, was implemented in order to model mode I interlaminar fracture toughness of multiscale CNT/CNF S2-Glass/epoxy composites. For all the investigated case studies the adopted multiscale based strategies revealed to be mostly effective in capturing the most significant damage-related parameters at the lower scales, influencing the structural mechanisms, acting at the structure/component scale

Open BIM Standards: A Review of the Processes for Managing Existing Structures in the Pre- and Post-Earthquake Phases

The problem of managing existing structures before and after seismic events has led to the development of many di erent strategies across the lobe. These aim to mitigate the catastrophic e ects of earthquakes on the occupants of a building, as well as improve the management of the emergency that inevitably ensues. This paper explores the use of an openBIM approach to resolve the issues referred to above, which is possible because of two new standards: Industry Foundation Classes and Information Delivery Manuals. A review of the most popular strategies adopted in both the pre- and post-earthquake phases is conducted using a process map. This organizes the relevant steps and processes into tasks, and additionally identifies the points at which information is produced and exchanged and the party responsible for doing so. Also described is how BIM models can be utilized in essential pre- and post-earthquake activities, as well as current benefits and ongoing developments intended to improve the processes themselves

A role for nuclear stretching and NPCs changes in the cytoplasmic-nuclear trafficking of YAP: An experimental and numerical modelling approach

Mechanical forces, acting on eukaryotic cells, are responsible for cell shape, cell proliferation, cell polarity, and cell differentiation thanks to two cells abilities known as mechanosensing and mechanotransduction. Mechanosensing consists of the ability of a cell to sense mechanical cues, while mechanotransduction is the capacity of a cell to respond to these signals by translating mechanical stimuli into biochemical ones. These signals propagate from the extracellular matrix to the nucleus with different well known physical connections, but how the mechanical signals are transduced into biochemical ones remains an open challenge. Recent findings showed that the cell-generated forces affect the translocation of transcription factors (TFs) from the cytoplasm to the nucleus. This mechanism is affected by the features of nuclear pore complexes. Owing to the complex patterns of strains and stresses of the nuclear envelope caused by cytoskeletal forces, it is likely that the morphology of NPC changes as cytoskeleton assemblies’ change. This may ultimately affect molecular transport through the nucleus, hence altering cell functions. Among the various TFs, Yes-associated protein (YAP), which is typically involved in cell proliferation, survival, and differentiation, is able to activate specific pathways when entrapped into the cell nucleus. Here, starting from experimental results, we develop a multiscale finite element (FE) model aimed to simulate the macroscopic cell spreading and consequent changes in the cell mechanical behaviour to be related to the NPCs changes and YAP nuclear transport

Iodocionin, a Cytotoxic Iodinated Metabolite from the Mediterranean Ascidian Ciona edwardsii

Chemical investigation of the Mediterranean ascidian Ciona edwardsii has been performed, leading to the isolation of two halogenated compounds: a new tyrosineiodinated derivative iodocionin (1) and the relevant brominated analogue (2), previously isolated from a Caribbean sponge. The structure of the new compound 1 has been assigned on the basis of spectroscopic analysis. Both compounds were tested for cytotoxicity in vitro against two different cancer cell lines, L5178Y (mouse lymphoma) and PC-12 (rat pheochromocytoma). Iodocionin was shown to possess significant and selective activity against lymphoma cells with an IC50 of 7.75 μg/mL

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries