29 research outputs found

    Protection of Aluminum Foils against Environmental Corrosion with Graphene-Based Coatings

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    Commercial aluminum foils were coated by graphene oxide, and its functionalized derivatives and the corrosion performance of the coated specimens were examined in acidic conditions (lithium perchlorate and sulfuric acid). Electrochemical experiments have shown that all graphene oxide-coated specimens provided up to 96% corrosion inhibition efficiency with a corresponding lower corrosion rate compared to the bare aluminum foil. Our results clearly show that graphene-related materials offer viable alternatives for the protection of aluminum, and this opens up a number of possibilities for its use in a number of commercial applications

    FreSh: A Lock-Free Data Series Index

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    We present FreSh, a lock-free data series index that exhibits good performance (while being robust). FreSh is based on Refresh, which is a generic approach we have developed for supporting lock-freedom in an efficient way on top of any localityaware data series index. We believe Refresh is of independent interest and can be used to get well-performed lock-free versions of other locality-aware blocking data structures. For developing FreSh, we first studied in depth the design decisions of current state-of-the-art data series indexes, and the principles governing their performance. This led to a theoretical framework, which enables the development and analysis of data series indexes in a modular way. The framework allowed us to apply Refresh, repeatedly, to get lock-free versions of the different phases of a family of data series indexes. Experiments with several synthetic and real datasets illustrate that FreSh achieves performance that is as good as that of the state-of-the-art blocking in-memory data series index. This shows that the helping mechanisms of FreSh are light-weight, respecting certain principles that are crucial for performance in locality-aware data structures.This paper was published in SRDS 2023.Comment: 12 pages, 18 figures, Conference: Symposium on Reliable Distributed Systems (SRDS 2023

    Hazard Assessment of Abraded Thermoplastic Composites Reinforced with Reduced Graphene Oxide

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    Graphene-related materials (GRMs) are subject to intensive investigations and considerable progress has been made in recent years in terms of safety assessment. However, limited information is available concerning the hazard potential of GRM-containing products such as graphene-reinforced composites. In the present study, we conducted a comprehensive investigation of the potential biological effects of particles released through an abrasion process from reduced graphene oxide (rGO)-reinforced composites of polyamide 6 (PA6), a widely used engineered thermoplastic polymer, in comparison to as-produced rGO. First, a panel of well-established in vitro models, representative of the immune system and possible target organs such as the lungs, the gut, and the skin, was applied. Limited responses to PA6-rGO exposure were found in the different in vitro models. Only as-produced rGO induced substantial adverse effects, in particular in macrophages. Since inhalation of airborne materials is a key occupational concern, we then sought to test whether the in vitro responses noted for these materials would translate into adverse effects in vivo. To this end, the response at 1, 7 and 28 days after a single pulmonary exposure was evaluated in mice. In agreement with the in vitro data, PA6-rGO induced a modest and transient pulmonary inflammation, resolved by day 28. In contrast, rGO induced a longer-lasting, albeit moderate inflammation that did not lead to tissue remodeling within 28 days. Taken together, the present study suggests a negligible impact on human health under acute exposure conditions of GRM fillers such as rGO when released from composites at doses expected at the workplace

    “There Is No (Where a) Face Like Home”: Recognition and Appraisal Responses to Masked Facial Dialects of Emotion in Four Different National Cultures

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    The theory of universal emotions suggests that certain emotions such as fear, anger, disgust, sadness, surprise and happiness can be encountered cross-culturally. These emotions are expressed using specific facial movements that enable human communication. More recently, theoretical and empirical models have been used to propose that universal emotions could be expressed via discretely different facial movements in different cultures due to the non-convergent social evolution that takes place in different geographical areas. This has prompted the consideration that own-culture emotional faces have distinct evolutionary important sociobiological value and can be processed automatically, and without conscious awareness. In this paper, we tested this hypothesis using backward masking. We showed, in two different experiments per country of origin, to participants in Britain, Chile, New Zealand and Singapore, backward masked own and other-culture emotional faces. We assessed detection and recognition performance, and self-reports for emotionality and familiarity. We presented thorough cross-cultural experimental evidence that when using Bayesian assessment of non-parametric receiver operating characteristics and hit-versus-miss detection and recognition response analyses, masked faces showing own cultural dialects of emotion were rated higher for emotionality and familiarity compared to other-culture emotional faces and that this effect involved conscious awareness

    Wettability of graphene by molten polymers

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    Graphene wetting by polymers is a critical issue to both the success of polymer-aided transfer of large size sheets onto specific substrates and to the development of well performing nanocomposites. Here we show for the first time that high temperature contact angle measurements can be performed to investigate the wettability of CVD graphene by molten polymers. In particular, poly(methyl methacrylate), a widely used polymer support for CVD graphene transfer, has been adopted herein for this proof-of-concept study and the values of contact angle and work of adhesion have been provided in the temperature range 170–200 °C

    Tribology of Copper Metal-Matrix Composites Reinforced with Fluorinated Graphene Oxide Nanosheets: Implications for Solid Lubricants in Mechanical Switches

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    Applications of copper coatings on steel switching mechanisms are abundant owing to their high conductivities and corrosion resistance that they impart on the engineered assemblies. However, applications of these coatings on such moving parts are limited due to their poor tribological properties; tendencies to generate high friction and susceptibility to degradative wear. In this study, we have fabricated a fluorinated graphene oxide-copper metal matrix composite (FGO-CMMC) on an AISI52100 bearing steel substrate by a simple electrodeposition process in water. The FGO-CMMC coatings exhibited excellent lubrication performance under pin-on-disk (PoD) tribological sliding at 1N load, which reduced CoF by 63 and 69%, compared to the GO-CMMC and pure copper coatings that were also prepared. Furthermore, FGO-CMMC achieved low friction and low wear at higher sliding loads. The lubrication enhancement of the FGO-CMMCs is attributed to the tribochemical reaction of FGO with the AISI 52100 steel counterface initiated by sliding load. The formation of an asymmetric tribofilm structure on the sliding track is critical; the performance of the FGO/Cu tribofilm formed in the track is boosted by the continued fluorination of the counterface surface during PoD sliding, passivating the tribosystem from adhesion-driven breakdown. The FGO-CMMC and GO-CMMC coatings also provide increased corrosion protection reaching 94.2 and 91.6 % compared to the bare steel substrate, allowing for the preservation of the long-term low friction performance of the coating. Other influences include the improved interlaminar shear strength of the FGO-containing composite. The excellent lubrication performance of copper coatings by FGO incorporation makes the CMMC a promising solid lubricant candidate for use in mechanical engineering applications
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