Micro-CT imaging and finite element models reveal how sintering temperature affects the microstructure and strength of bioactive glass-derived scaffolds

: This study focuses on the finite element simulation and micromechanical characterization of bioactive glass-ceramic scaffolds using Computed micro Tomography ([Formula: see text]CT) imaging. The main purpose of this work is to quantify the effect of sintering temperature on the morphometry and mechanical performance of the scaffolds. In particular, the scaffolds were produced using a novel bioactive glass material (47.5B) through foam replication, applying six different sintering temperatures. Through [Formula: see text]CT imaging, detailed three-dimensional images of the scaffold's internal structure are obtained, enabling the extraction of important geometric features and how these features change with sintering temperature. A finite element model is then developed based on the [Formula: see text]CT images to simulate the fracture process under uniaxial compression loading. The model incorporates scaffold heterogeneity and material properties-also depending on sintering temperature-to capture the mechanical response, including crack initiation, propagation, and failure. Scaffolds sintered at temperatures equal to or higher than 700 [Formula: see text]C exhibit two-scale porosity, with micro and macro pores. Finite element analyses revealed that the dual porosity significantly affects fracture mechanisms, as micro-pores attract cracks and weaken strength. Interestingly, scaffolds sintered at high temperatures, the overall strength of which is higher due to greater intrinsic strength, showed lower normalized strength compared to low-temperature scaffolds. By using a combined strategy of finite element simulation and [Formula: see text]CT-based characterization, bioactive glass-ceramic scaffolds can be optimized for bone tissue engineering applications by learning more about their micromechanical characteristics and fracture response

TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Seasonal dynamics of active SAR11 ecotypes in the oligotrophic Northwest Mediterranean Sea

A seven-year oceanographic time series in NW Mediterranean surface waters was combined with pyrosequencing of ribosomal RNA (16S rRNA) and ribosomal RNA gene copies (16S rDNA) to examine the environmental controls on SAR11 ecotype dynamics and potential activity. SAR11 diversity exhibited pronounced seasonal cycles remarkably similar to total bacterial diversity. The timing of diversity maxima was similar across narrow and broad phylogenetic clades and strongly associated with deep winter mixing. Diversity minima were associated with periods of stratification that were low in nutrients and phytoplankton biomass and characterised by intense phosphate limitation (turnover time80%) by SAR11 Ia. A partial least squares (PLS) regression model was developed that could reliably predict sequence abundances of SAR11 ecotypes (Q2=0.70) from measured environmental variables, of which mixed layer depth was quantitatively the most important. Comparison of clade-level SAR11 rRNA:rDNA signals with leucine incorporation enabled us to partially validate the use of these ratios as an in-situ activity measure. However, temporal trends in the activity of SAR11 ecotypes and their relationship to environmental variables were unclear. The strong and predictable temporal patterns observed in SAR11 sequence abundance was not linked to metabolic activity of different ecotypes at the phylogenetic and temporal resolution of our study

TRY plant trait database - enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Amazon tree dominance across forest strata

The forests of Amazonia are among the most biodiverse plant communities on Earth. Given the immediate threats posed by climate and land-use change, an improved understanding of how this extraordinary biodiversity is spatially organized is urgently required to develop effective conservation strategies. Most Amazonian tree species are extremely rare but a few are common across the region. Indeed, just 227 ‘hyperdominant’ species account for >50% of all individuals >10 cm diameter at 1.3 m in height. Yet, the degree to which the phenomenon of hyperdominance is sensitive to tree size, the extent to which the composition of dominant species changes with size class and how evolutionary history constrains tree hyperdominance, all remain unknown. Here, we use a large floristic dataset to show that, while hyperdominance is a universal phenomenon across forest strata, different species dominate the forest understory, midstory and canopy. We further find that, although species belonging to a range of phylogenetically dispersed lineages have become hyperdominant in small size classes, hyperdominants in large size classes are restricted to a few lineages. Our results demonstrate that it is essential to consider all forest strata to understand regional patterns of dominance and composition in Amazonia. More generally, through the lens of 654 hyperdominant species, we outline a tractable pathway for understanding the functioning of half of Amazonian forests across vertical strata and geographical locations

Applicazione della Realtà Virtuale nell'Analisi della Sicurezza dei Sistemi di Trasporto

Gli incidenti stradali sono una delle principali cause di morte per tutte le fasce d'età; questo vale, con percentuali diverse, per tutti gli utenti della strada. Essendo un problema globale, richiede urgente attenzione. In questa tesi il comportamento degli utenti della strada e le loro interazioni sono stati studiati con l'aiuto della realtà virtuale. È stata studiata l'interazione tra utenti della strada, infrastrutture e veicoli. Nel complesso, questa ricerca ha cercato di rispondere a diverse domande, come ad esempio: È possibile migliorare la sicurezza stradale con la realtà virtuale? È possibile migliorare il comportamento degli utenti della strada con la realtà virtuale? Questa tesi è il connubio tra realtà virtuale (sia non immersiva che immersiva), trasporti e sicurezza, e tecnologia (simulatori, visori). La scelta della realtà virtuale è stata dettata dai numerosi vantaggi che essa presenta, ovviando a tutte le insidie che si avrebbero con prove sul campo. Una ricerca sugli automobilisti con realtà virtuale di tipo non immersiva è stata condotta presso il Laboratorio Trasporti del Dipartimento di Ingegneria Civile, Edile e Ambientale dell'Università di Padova. Inoltre, uno studio riguardante i motociclisti è stato invece condotto presso il Laboratorio HRT del Dipartimento di Psicologia Generale, della stessa Università. Infine, uno studio con realtà virtuale immersiva è stato proposto per l'utente vulnerabile per eccellenza: il pedone. I circa 300 soggetti coinvolti erano utenti della strada, tra cui automobilisti (Capitolo 2), motociclisti (Capitolo 3) e pedoni (Capitolo 4). Grazie al training virtuale, con i tre diversi dispositivi, è stato possibile ottenere miglioramenti nel comportamento e quindi scoprire i reali benefici della realtà virtuale nel mondo della sicurezza dei trasporti. In primo luogo, dagli studi del Capitolo 2, è stato possibile sottolineare quanto sia fondamentale avere una corretta comprensione di un Advanced driver assistance systems (ADAS) per il suo corretto funzionamento. Attraverso l'implementazione di diversi ADAS per il controllo laterale del veicolo e la somministrazione con la tecnica del precision teaching, sono stati determinati i benefici che questi sistemi producono. Poiché il controllo laterale è una variabile di particolare interesse in termini di sicurezza, a causa delle sue numerose implicazioni ed effetti, i risultati ottenuti da queste tecnologie sono incoraggianti per la mitigazione del rischio stradale e, di conseguenza, degli incidenti. I risultati proposti, sottolineando i benefici di queste tecnologie nel tempo, confermano che si tratta di un approccio legittimo sia in termini di progettazione ADAS che nell'uso di tecniche di apprendimento. In secondo luogo, considerando gli studi dei capitoli 2 e 3, si potrebbe sostenere che sia per i conducenti di auto che di moto con stile di guida aggressivo, la presentazione di feedback per ridurre eventi bruschi e le violazioni dei limiti di velocità, produce una riduzione significativa di queste variabili. I risultati ottenuti sono stati nuovamente rilevanti in termini di sicurezza stradale: grazie alle metodologie testate in questo lavoro è possibile progettare programmi per correggere il comportamento degli utenti della strada più aggressivi e, di conseguenza, più pericolosi. Per quanto riguarda i motociclisti, è stato anche dimostrato che i benefici di questi sistemi persistono nel tempo. Infine, per quanto riguarda lo studio dei pedoni al Capitolo 4, questa tesi rappresenta uno dei primi lavori in Italia di educazione alla sicurezza stradale dei bambini con la realtà virtuale. La presente indagine, infatti, essendo parte di un progetto più ampio dedicato agli utenti vulnerabili, ha indagato il comportamento dei bambini nell'ambiente stradale. In questo senso, questo studio si è rivelato innovativo sia nei suoi obiettivi educativi, sia nei mezzi impiegati per raggiungerli.Road traffic crashes are a leading cause of death across all age groups; this applies, with different percentages, to all road users. Being a global burden, this issue demands urgent attention. In this thesis road users’ behavior and their interactions are studied with the aid of virtual reality. Road users were accordingly inserted in virtual road environments, with virtual simulators. The interaction between road users, infrastructures, and vehicles was investigated. Overall, this research attempts to answer several questions, as such: Is it possible to improve road safety with virtual reality? Is it possible to improve road user behavior with virtual reality? This thesis has carefully interwoven virtual reality (both non-immersive and immersive), transport and safety, with technology (simulators, visors). The choice of virtual reality was dictated by the many advantages it presents, obviating all the pitfalls related to risk during field tests. A research regarding non-immersive virtual reality for car drivers was conducted at the Transportation Laboratory at the Department of Civil, Environmental and Architectural Engineering at University of Padua. Moreover, a study concerning motorcyclists was instead conducted at the HRT Laboratory of the Department of General Psychology. Eventually, a study with immersive virtual reality was proposed for the vulnerable user par excellence, the pedestrian. The approximately 300 subjects involved were road users, including car drivers (Chapter 2), motorcyclists (Chapter 3) and pedestrians (Chapter 4). Thanks to the virtual training, with three different devices, it was possible to obtain improvements in behavior and therefore to uncover real benefits of virtual reality in the world of transport safety. Firstly, from the studies of Chapter 2, it was possible to stress how crucial it is to have a proper understanding of an ADAS for its correct functioning. In other words, it was illustrated to what extent an adequate understanding of ADAS is pivotal to benefit from all its advantages. Through the implementation of several ADAS for the lateral control of the vehicle and the administration with precision teaching technique, it was overall investigated how many considerable benefits they produce. Since lateral control is a variable of particular interest in terms of safety, because of its many implications and effects, the results obtained from these technologies are encouraging for the mitigation of road risk and, consequently, of accidents. The results proposed, by underlining the benefits of these technologies over time, confirm that this is a legitimate approach both in terms of ADAS design and in the use of learning techniques. Secondly, considering the studies in Chapters 2 and 3, it might be argued that for both car and motorcycle drivers with aggressive driving style, the presentation of feedback to reduce elevated gravitational-force event (EGFE) and speed limit violations, produces a significant reduction of these variables. The results obtained were again relevant in terms of road safety: thanks to the methodologies tested in this work it is possible to design programs to correct the behavior of the most aggressive, and by implication most dangerous, road users. With respect to motorcyclists, it was also demonstrated that the benefits of these systems persist over time. Finally, as far as the study of pedestrians is concerned, this thesis represents one of the first works in Italy of road safety education of children with virtual reality. The present inquiry, indeed, being part of a broader project dedicated to vulnerable users, investigated children's behavior in the street environment. In this sense, this study proved to be innovative both in its educational objectives, and in the means employed to achieve them