2,744 research outputs found
Tribochemistry of graphene on iron and its possible role in lubrication of steel
Recent tribological experiments revealed that graphene is able to lubricate
macroscale steel-on-steel sliding contacts very effectively both in dry and
humid conditions. This effect has been attributed to a mechanical action of
graphene related to its load-carrying capacity. Here we provide further insight
into the functionality of graphene as lubricant by analysing its tribochemical
action. By means of first principles calculations we show that graphene binds
strongly to native iron surfaces highly reducing their surface energy. Thanks
to a passivating effect, the metal surfaces coated by graphene become almost
inert and present very low adhesion and shear strength when mated in a sliding
contact. We generalize the result by establishing a connection between the
tribological and the electronic properties of interfaces, which is relevant to
understand the fundamental nature of frictional forces.Comment: 19 pages, 6 figure
Insigths into the tribochemistry of silicon-doped carbon based films by ab initio analysis of water/surface interactions
Diamond and diamond-like carbon (DLC) are used as coating materials for
numerous applications, ranging from biomedicine to tribology. Recently, it has
been shown that the hydrophilicity of the carbon films can be enhanced by
silicon doping, which highly improves their biocompatibility and frictional
performances. Despite the relevance of these properties for applications, a
microscopic understanding on the effects of silicon is still lacking. Here we
apply ab initio calculations to study the interaction of water molecules with
Si-incorporated C(001) surfaces. We find that the presence of Si dopants
considerably increases the energy gain for water chemisorption and decreases
the energy barrier for water dissociation by more than 50%. We provide a
physical rational for the phenomenon by analysing the electronic charge
displacements occuring upon adsorption. We also show that once hydroxylated,
the surface is able to bind further water molecules much strongly than the
clean surface via hydrogen-bond networks. This two-step process is consistent
with and can explain the enhanced hydrophilic character observed in
carbon-based films doped by silicon
Multilayer Network Analysis of Innovation Intermediaries' Activities
Policymakers wishing to enhance innovation processes in small and medium-sized enterprises increasingly channel their interventions through innovation intermediaries. However, limited empirical research exists regarding the activities and performance of intermediaries, with most contributions taking a qualitative approach and focusing on the role of intermediaries as brokers. In this paper, we analyse the extent to which innovation intermediaries, through their engagement in different activities, support the creation of communities of other agents. We use multilayer network analysis techniques to simultaneously represent the many types of interactions promoted by intermediaries. Furthermore, by originally applying the Infomap algorithm to our multilayer network, we assess the contribution of the agents involved in different activities promoted by intermediaries, and we identify the emerging multilayer communities and the intercohesive agents that span across several communities. Our analysis highlights the potential and the critical features of multilayer analysis for policy design and evaluation
Ab Initio Calculation of the Adhesion and Ideal Shear Strength of Planar Diamond Interfaces with Different Atomic Structure and Hydrogen Coverage
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Ab initio insights into the interaction mechanisms between H, HO, and O molecules with diamond surfaces
Diamond displays outstanding chemical, physical, and tribological properties,
making it attractive for numerous applications ranging from biomedicine to
tribology. However, the reaction of the materials with molecules present in the
air, such as oxygen, hydrogen, and water, could significantly change the
electronic and tribological properties of the films. In this study, we
performed several density functional theory calculations to construct a
database for the adsorption energies and dissociation barriers of these
molecules on the most relevant diamond surfaces, including C(111), C(001), and
C(110). The adsorption configurations, reaction paths, activation energies, and
their influence on the structure of diamond surfaces are discussed. The results
indicate that there is a strong correlation between adsorption energy and
surface energy. Moreover, we found that the dissociation processes of oxygen
molecules on these diamond surfaces can significantly alter the surface
morphology and may affect the tribological properties of diamond films. These
findings can help to advance the development and optimization of devices and
antiwear coatings based on diamond
The challenge of brain complexity: A brief discussion about a fractal intermittency-based approach
In the last years, the complexity paradigm is gaining momentum in many research fields where large multidimensional datasets are made available by the advancements in instrumental technology. A complex system is a multi-component system with a large number of units characterized by cooperative behavior and, consequently, emergence of well-defined self-organized structures, such as communities in a complex network. The self-organizing behavior of the brain neural network is probably the most important prototype of complexity and is studied by means of physiological signals such as the ElectroEncephaloGram (EEG). Physiological signals are typically intermittent, i.e., display non-smooth rapid variations or crucial events (e.g., cusps or abrupt jumps) that occur randomly in time, or whose frequency changes randomly. In this work, we introduce a complexity-based approach to the analysis and modeling of physiological data that is focused on the characterization of intermittent events. Recent findings about self-similar or fractal intermittency in human EEG are reviewed. The definition of brain event is a crucial aspect of this approach that is discussed in the last part of the paper, where we also propose and discuss a first version of a general-purpose event detection algorithm for EEG signal
Enhancing the resilience of social infrastructures: issues on agents, artefacts and processes. Proceedings of the 2016 Modena Workshop
In the social sciences domain, the term 'resilience' is usually associated to a wide set of changes that affect people and their communities. In particular, both the Hyogo Framework for Action 2005–2015 and the Sendai Framework explicitly focus on the way in which communities face both natural and man-made hazards. To this respect, both material and non-material infrastructures play a critical role, hence deserving a specific focus when assessing local communities' level of resilience. Among them, this paper focuses on: health services, social services, government (according to a multi-level perspective, from the national to the local level), communication infrastructure (i.e. specific tools to interconnect all aforementioned networks). Firstly, this paper discusses some of the most important issues and theoretical frameworks that should be addressed in the analysis of the processes of enhancing the resilience of social infrastructures. Secondly, the discussion that took place in a workshop promoted in May 2016 as the outcome of a one-year dialogue across a group of EU researchers is returned. The debate moves from some theoretical perspectives on resilience and it eventually returns some case studies and real experiences, such as the actions of local governments and the role of risk communication
The Series on "How to Deal with Early Stage Lung Cancer: Sublobar Resections as A Possible Choice (Report of the 2019 Spring Meeting of Italian Society of Thoracic Surgery)?"
This series is the result of the work of different specialists from all around Italy and from Fudan University in Shanghai, who
gathered in Milan on April 2019, to attend the Spring Meeting of Italian Society of Thoracic Surgery (SICT). The meeting
discussed new evidences suggesting sublobar resection as the elective surgical treatment of early stage lung cancer
Parenting infants at the times of COVID-19: A cross-sectional study on parental stress in the province of Modena (Northern Italy)
Background and aim of the work: The advent of the COVID-19 pandemic and the consequent measures to prevent virus’s spread particularly affected families with young children, that represent a complex system characterized by a constant interaction between the infant’s and the parent’s well-being. The present study aims to investigate the parenting stress experienced by parents with 6-month-old healthy infants surveyed from September 2019 to April 2021 in the Modena province (Northern Italy). Research design and methods: We carried out a cross-sectional study using the Parenting Stress Index-Short Form (PSI-SF) questionnaire to assess stress levels in the parent-child system. Since the questionnaire is meant to be self-completed by the participant, the survey could continue to be conducted remotely during the pandemic lockdown months. Results: Most parents exhibited physiological stress scores, but parents who have been interviewed during the pandemic period had a higher prevalence of stress problems. Subjects in the COVID group also showed a drop in the defensive response and a lower prevalence of stress problems when parenting siblings. Conclusions: These findings underline the importance of early detection of isolation’s negative effects on households and strengthen the need for tailored familial support during stressful events, in order to pro-mote parent and children’s emotional well-being
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