Trapping of oil in an epoxy-based polymer matrix with activated carbon and its effect on tribological behavior

The incorporation of lubricating oil at high levels in the epoxy composite materials makes it possible to obtain materials with low friction and wear. This article evaluates the wear behaviour of an epoxy-based composite obtained by the addition of lubricating oil and activated carbon. An oil content of up to 31wt% is trapped and maintained in the matrix by the presence of activated carbon. The wear experiments are carried out on a pin-on-disk type tribometer. The tests are carried out on pins of different compositions sliding on steel discs (XC48) under dry friction conditions. The effect of various parameters such as speed and loading has been investigated. The wear surfaces are analyzed by using a scanning electron microscope to observe the different wear mechanisms. The results show that the addition of activated carbon made it possible to trap large quantities of oil in the matrix. This decreased greatly the coefficient of friction and increased the capacity of the sample to withstand higher values of sliding velocities and pressures

Experimental and numerical analysis of the fields of the frozen stresses in an epoxy sphere using the stress-freezing method and mechanical slicing

The stresses induced by a mechanical contact imposed on a birefringent sphere have been studied experimentally and numerically. The birefringent sphere is machined from a birefringent parallelepiped on a high speed numerically controlled machine. The residual stresses developed in the birefringent sphere have been eliminated by a heat treatment relaxation. The technique of freezing and mechanical cutting in thin slices was used. In the case of 3D photoelasticity, the frozen stress techniques, which are very much used, may introduce residual stresses in the cut up slices. Although the means to avoid the introduction of these residual stresses are well established, these techniques remain time consuming. Slices are analyzed on a polariscope using plane polarized light and circular polarized light. The photoelastic fringes are used to determine the principal directions of the stresses as well as the values of the stresses. A numerical simulation using the finite elements made it possible to make a comparison with the experimental results. The analysis shows a good correlation between experimental measurements and numerical simulation

Experimental and numerical analysis of the fields of the frozen stresses in an epoxy sphere using the stress-freezing method and mechanical slicing

The stresses induced by a mechanical contact imposed on a birefringent sphere have been studied experimentally and numerically. The birefringent sphere is machined from a birefringent parallelepiped on a high speed numerically controlled machine. The residual stresses developed in the birefringent sphere have been eliminated by a heat treatment relaxation. The technique of freezing and mechanical cutting in thin slices was used. In the case of 3D photoelasticity, the frozen stress techniques, which are very much used, may introduce residual stresses in the cut up slices. Although the means to avoid the introduction of these residual stresses are well established, these techniques remain time consuming. Slices are analyzed on a polariscope using plane polarized light and circular polarized light. The photoelastic fringes are used to determine the principal directions of the stresses as well as the values of the stresses. A numerical simulation using the finite elements made it possible to make a comparison with the experimental results. The analysis shows a good correlation between experimental measurements and numerical simulation

Depositional architecture, provenance, and tectonic/eustatic modulation of Miocene submarine fans in the Shikoku Basin: Results from Nankai Trough Seismogenic Zone Experiment

Seismostratigraphy, coring, and logging while drilling during Integrated Ocean Drilling Program Expeditions 319, 322, and 333 (Sites C0011/C0012) show three Miocene submarine fans in the NE Shikoku Basin, with broadly coeval deposits at Ocean Drilling Program Site 1177 and Deep Sea Drilling Project Site 297 (NW Shikoku Basin). The sediment dispersal patterns have major implications for paleogeographies at that time. The oldest, finer-grained (Kyushu) fan has sheet-like geometry; quartz-rich flows were fed mostly from an ancestral landmass in the East China Sea. During prolonged hemipelagic mud deposition at C0011-C0012 (~12.2 to 9.1 Ma), sand supply continued at Sites 1177 and 297. Sand delivery to much of the Shikoku Basin halted during a phase of sinistral strike slip to oblique plate motion, after which the Daiichi Zenisu Fan (~9.1 to 8.0 Ma) was fed by submarine channels. The youngest fan (Daini Zenisu; ~8.0 to 7.6 Ma) has sheet-like geometry with thick-bedded, coarse-grained pumiceous sandstones. The pumice fragments were fed from a mixed provenance that included the collision zone of the Izu-Bonin and Honshu Arcs. The shift from channelized to sheet-like flows was favored by renewal of relatively rapid northward subduction, which accentuated the trench as a bathymetric depression. Increased sand supply appears to correlate with long-term eustatic lowstands of sea level. The stratigraphic position and 3-D geometry of the sandbodies have important implications for subduction-related processes, including the potential for focused fluid flow and fluid overpressures above and below the plate boundary fault: In sheet-like sands, pathways for fluid flow have greater horizontal permeability compared with those in channel sands

Recent progress in low-carbon binders

The development of low-carbon binders has been recognized as a means of reducing the carbon footprint of the Portland cement industry, in response to growing global concerns over CO2 emissions from the construction sector. This paper reviews recent progress in the three most attractive low-carbon binders: alkali-activated, carbonate, and belite-ye'elimite-based binders. Alkali-activated binders/materials were reviewed at the past two ICCC congresses, so this paper focuses on some key developments of alkali-activated binders/materials since the last keynote paper was published in 2015. Recent progress on carbonate and belite-ye'elimite-based binders are also reviewed and discussed, as they are attracting more and more attention as essential alternative low-carbon cementitious materials. These classes of binders have a clear role to play in providing a sustainable future for global construction, as part of the available toolkit of cements

Etude analytique numérique et expérimentale du contact mécanique poinçon sur plan

Photoelastic analysis of stresses developed in a birefringent plan which undergoes compression via an aluminium punch was conducted. The stress field was analysed on the whole model and particularly in the neighbourhood of the contact zone. The principal stresses difference was easily determined by using the isochromatic fringes obtained experimentally. A numerical simulation was done by using “castem package”. A whole field comparison of the experimental fringes with the numerical ones and a local analysis using the principal stresses difference developed in the model, along the direction of the applied load, allowed us to validate the theoretical and the numerical approach. Good agreements have been observed

The awareness and empowerment aspects of the needlesticks and other sharps injuries and reporting in nursing education: a cross-sectional survey

Background: Occurrence and underreporting of needlesticks and other sharps injuries (NSIs) are still immediate concerns among nursing students. This study examined the relationship between occupational health and safety (OHS) awareness and empowerment levels of nursing students and the occurrence and reporting of NSIs. Methods: This cross-sectional study was conducted among purposively selected 840 students in a nursing school in 2018–2019. A self-report questionnaire was used to collect data about students’ sociodemographic characteristics, OHS awareness and empowerment levels, and NSIs characteristics. After bivariate analyses, multivariate logistic regression was used. Results: The number of evaluated questionnaires was 469, for a response rate of 55.8%. Participants, 21.2% (n = 99), had suffered NSIs, and 47.8% had reported their injuries. The NSIs were statistically related to age, academic year, working night shift, OHS awareness level of students, and the number of clinical placements completed by students. The odds of experiencing NSIs was 2.3 (95% confidence interval [CI] = [1.0, 5.3]) times higher in male students, 4.3 (95% CI = [2.4, 7.4]) times higher in those beyond the second academic year, and 2.5 (95% CI = [1.4, 4.4]) times higher in those who had received OHS training for a shorter period than the average duration. Conclusion/Application to practice: The levels of awareness and empowerment were higher in students who received OHS and NSIs prevention training and those who received OHS training for the above-average duration. Increasing awareness and empowerment levels of nursing students through training can reduce the occurrence and the underreporting of NSIs