RESUMEN
Mechanical degradation (erosion) of plastics in the marine environment has been reported in many literature studies but without quantitative information. This type of degradation is crucial as it accounts for most of the initial microplastic products, in marine environments (e.g., rivers and oceans). Here, we quantify the erosion of plastics by water-borne sediments under typical perpendicular water velocities and sand loads of turbid rivers and coastal oceans. Polypropylene (PP) shows the highest response to water-borne erosion, with a surface degradation rate of 5160 µm per year (4.44 mg per mm2 per year), compared with high-density polyethylene (HDPE) with a degradation rate of 1874 µm per year (1.79 mg per mm2 per year), resulting in the formation of microplastics (MPs). The rate of formation of such microplastic particles (>10 µm), as characterised by a laser direct infrared (LDIR) chemical imaging system, amounts to 669 particles per mm2 per year for PP and 187 particles per mm2 per year for HDPE, exhibiting average particle sizes of 60 µm and 23 µm in the same order. Furthermore, surface microscopy provided valuable insights into the dominant erosion mechanisms, revealing three distinct zones and the surface features reveal the brittle erosion behaviours. These results will enable a better assessment of degradation and lifetime prediction of plastics in turbid rivers and coastal oceans, allowing precise estimation of the rate of formation of MPs.
RESUMEN
Background and aims: Fatty streaks initiating the formation of atheromatous plaque appear in the tunica intima. The tunica media is not known to be a nidus for lipid accumulation initiating atherogenesis. We assessed changes to the tunica media in response to a micro-injury produced in the pig aorta. In addition, we assessed human carotid endarterectomy plaques for indication of atheroma initiation in the tunica media. Methods: Three healthy landrace female pigs underwent laparotomy to inject autologous blood and create micro-hematomas at 6 sites within the tunica media of the infrarenal abdominal aorta. These pigs were fed a high-fat diet (HFD) for 4-12 weeks. Post-mortem aortas from all pigs, including a control group of healthy pigs, were serially stained to detect lipid deposits, vasa vasora (VV), immune cell infiltration and inflammatory markers, as well as changes to the vascular smooth muscle cell (vSMC) compartment. Moreover, 25 human carotid endarterectomy (CEA) specimens were evaluated for their lipid composition in the tunica media and intima. Results: High lipid clusters, VV density, and immune cell infiltrates were consistently observed at 5 out of 6 injection sites under prolonged hyperlipidemia. The hyperlipidemic diet also affected the vSMC compartment in the tunica media adjacent to the tunica adventitia, which correlated with VV invasion and immune cell infiltration. Analysis of human carotid specimens post-CEA indicated that 32% of patients had significantly greater atheroma in the tunica media than in the arterial intima. Conclusion: The arterial intima is not the only site for atherosclerosis initiation. We show that injury to the media can trigger atherogenesis.
RESUMEN
This qualitative study aimed to identify mental health hazards in the offshore oil and gas industry, as well as the role of the personality types of the Five Factor Model (FFM) in coping with these stressors. A focus group with 8 participants and a pilot study with 5 participants were conducted. Results showed that several stressors are currently present for Australian offshore oil and gas employees, in particular COVID-19 and the resulting negative effects on rosters, working hours, job security and time spent away from home. Other stressors revealed by participants were lack of space, working in a high-risk environment, stigma, helicopter travel and pressure to keep up with production. Poor safety behaviours were associated with neuroticism, extraversion and openness, while risk avoidance appear to be associated with agreeableness and conscientiousness. Tolerance to shift work was positively related to extraversion, yet negatively associated to neuroticism. Furthermore, neuroticism showed a negative association with help-seeking and productivity, as well as higher levels of concern relating to COVID-19 and job uncertainty. As personality traits are enduring throughout life, it is vital that employees are managed effectively through workplace interventions so that they are able to cope effectively, particularly during stressful events.