g r a p h i c a l a b s t r a c t Micellar structure of asphaltene in a dispersing medium of lighter resins, aromatics, and saturates. a b s t r a c tIn the colloidal hypothesis of vacuum residua and asphalt, micelles are assumed to have an asphaltenic core with the greatest weight and aromaticity and an outer shell composed of lighter and less aromatic molecules. The true nature of the micelles, and the asphaltenic core in particular, has always been a debatable issue among asphalt researchers. One of the frequently asked questions is whether asphaltenes exist as stacked layers within the micelles or as single molecular units stabilized by resin molecules. In this paper, we investigate the correlation between the number of asphaltene sheets and the final stability of the system in a medium of asphaltene and resin components. Our evaluation is based on rigorous quantum mechanical calculations using a DFT-D approach. Our quantitative findings corroborate the view that the colloidal behavior of crude oil is better described by asphaltene-asphaltene associations. Moreover, our calculations show that if both asphaltene and resin are present, resin-asphaltene interactions are preferred over asphaltene-asphaltene interactions only if the number of resin molecules per micelle is greater than the number of asphaltene molecules per micelle.

The modified performance of bio-modified asphalt-binder is attributed to the alteration of intermolecular interactions between units of asphaltene stacks exposed to the bio-additive.

Scale-up manufacturing of engineered graphene-like nanomaterials to deliver the industry needs for development of high-performance polymer nanocomposites still remains a challenge. Herein, we introduce a quick and cost-effective approach to scalable production of functionalized graphite nanoplatelets using “kitchen blender” approach and Diels-Alder chemistry. We have shown that, in a solvent-free process and through a cycloaddition mechanism, maleic anhydride can be grafted onto the edge-localized electron rich active sites of graphite nanoplatelets (GNP) resulting from high collision force, called “graphite collision-induced activation”. The mechanical impact was modelled by applying the point charge method using density functional theory (DFT). The functionalization of GNP with maleic anhydride (m-GNP) was characterized using various spectroscopy techniques. In the next step, we used a recyclable process to convert m-GNP to the highly-reactive GNP (f-GNP) which exhibits a strong affinity towards the epoxy polymer matrix. It was found that at a low content of f-GNP e.g., 0.5 wt%, significant enhancements of ~54% and ~65% in tensile and flexural strengths of epoxy nanocomposite can be achieved, respectively. It is believed that this new protocol for functionalization of graphene nanomaterials will pave the way for relatively simple industrial scale fabrication of high performance graphene based nanocomposites.

Background: Nursing staff working in the operating room are exposed to risk factors that can cause musculoskeletal disorders (MSDs) and work-related disabilities. The use of ergonomics principles can help with the prevention of MSDs. This study aimed to examine the effect of an ergonomics educational program on MSDs among nursing staff working in the operating room. Methods: In this pragmatic parallel group quasi-randomized controlled clinical trial, 74 nursing staff working in the operating rooms of two teaching hospitals participated. The hospitals were randomly assigned to either the intervention or the control group and all nursing staff working in the operating room of each hospital were invited to take part in this research. They were initially assessed for the prevalence and risk of MSDs by using the Nordic questionnaire and the rapid entire body assessment (REBA) checklist. The intervention group received the ergonomics educational program and were assessed in two-week intervals over a period of three months. At the end of the study, the risk and prevalence of MSDs were compared between the intervention and control groups. Results: Statistically significant differences were reported between the groups in terms of the prevalence and risk of MSDs. The overall risk of MSDs decreased in the intervention group after the educational program (p = 0.03). The reduction in the prevalence of MSDs in the different parts of the body in the intervention group was as follows: ankle (p = 0.005), hand/wrist (p = 0.041), low back (p = 0.000), the neck (p = 0.003), hip (p = 0.001) and shoulder (p = 0.043). Conclusion: The education of nursing staff about ergonomics can influence the prevalence and risk of MSDs. Therefore, it should be incorporated into the degree education and on-the-job training initiatives for nurses working in the operating theatre in order to reduce workplace injuries and associated absences, and increase the quality of care delivered by them. This clinical trial has been registered in the Iranian Registry of Clinical Trials: IRCT2015081823677N1.