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BACKGROUND: The usage status, waste electrical and electronic equipment (WEEE) related to the smartphones of on-campus engineering students should be studied. Furthermore, the correlations between their smartphone profiles with energy consumption and environmental knowledge should be understood make measures improve their environmental behaviors. METHODS: Pro-environmental behavior and smartphone uses of the on-campus engineering undergraduates in Xi'an, China, were investigated with a self-designed questionnaire anonymously. The energy-saving activities they participated in and their e-waste treatment patterns were analyzed. RESULTS: Most of the respondents had a smartphone with large screen and high battery capacity, which also had long standby/usage time and frequent charging. Average daily power consumption of one smartphone was estimated to be 6.475 Wh. The surveyed undergraduate students changed their smartphones frequently, which produced large quantities of WEEE annually. CONCLUSION: Most on-campus students treated their waste smartphones in the proper ways. However, some of them were short of environmental knowledge about their smartphones. Some measures were suggested to improve their environmental concerns. The findings will help the on-campus engineering undergraduates in China to use their smartphones rationally and to deal with their waste smartphones appropriately.

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Surface roughness is used to quantitatively evaluate the surface topography of the workpiece subjected to mechanical processing. The optimal machining parameters are critical to getting designed surface roughness. The effects of cutting speed, feed rate, and depth of cut on the areal surface roughness of AZ31B Mg alloys were investigated via experiments combined with regression analysis. An orthogonal design was adopted to process the dry turning experiment of the front end face of the AZ31B bar. The areal surface roughness Sa and Sz of the end face were measured with an interferometer and analyzed through direct analysis and variance analysis (ANOVA). Then, an empirical model was established to predict the value of Sa through multiple regression analysis. Finally, a verification experiment was carried out to confirm the optimal combination of parameters for the minimum Sa and Sz, as well as the availability of the regression model for predicting Sa. The results show that both Sa and Sz of the machined end face reduce with the decrease in feed rate. The minimum of Sa and Sz reaches to 0.577 and 5.480 µm, respectively, with the cutting speed of 85 m/min, the feed rate of 0.05 mm/rev, and a depth of cut of 0.3 mm. The feed rate, depth of cut, and cutting speed contribute the greatest, the second and the smallest to Sa, respectively. The linear regression model can predict Sa of AZ31B machined with dry face turning, since the cutting speed, feed rate and depth of cut can explain 97.5% of the variation of Sa.

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In this study, a life cycle assessment (LCA) was used to investigate the environmental benefits of using styrene-butadiene-styrene (SBS) to modify polylactide (PLA)-based wood plastic composites (WPCs), with a process-based and input-output hybrid model. The results showed that one metric ton of the SBS-modified WPCs required 1.93 × 108 kJ of energy (Sample 2) and 46 m3 of water (Sample 4), and that it could produce 42.3 kg of solid waste (Sample 2) during its cradle-to-gate life cycle phases. The environmental impact load (EIL) and photochemistry oxidation potential (PCOP) accounted for the largest share, while the eutrophication potential (EP) took the smallest one. The total EIL index of Samples 1, 2, 3, and 4 added up to 1.942, 1.960, 1.899, and 1.838, respectively. The SBS-modified WPCs were found to be more environmentally friendly than their unmodified counterparts when they had the same or higher wood fiber (WF) content. SBS was viable to toughen the PLA-based WPCs from an environmental perspective. This cradle-to-gate LCA is likely to help optimize the manufacturing process and mitigate environmental impacts for the natural fiber-reinforced polymer biocomposites.

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Polylactide (PLA)-based composite materials reinforced with ball-milled celluloses were manufactured by extrusion blending followed by injection molding. Their surface morphology from impact fracture were imaged with scanning electron microscopy (SEM) and investigated by calculating their fractal dimensions. Then, linear regression was used to explore the relationship between fractal dimension and impact strength of the resultant cellulose/PLA composite materials. The results show that filling the ball-milled celluloses into PLA can improve the impact toughness of PLA by a minimum of 38%. It was demonstrated that the fracture pattern of the cellulose/PLA composite materials is different from that of pristine PLA. For the resultant composite materials, the fractal dimension of the impact fractured surfaces increased with increasing filling content and decreasing particle size of the ball-milled cellulose particles. There were highly positive correlations between fractal dimension of the fractured surfaces and impact strength of the cellulose/PLA composites. However, the linearity between fractal dimension and impact strength were different for the different methods, due to their different R-squared values. The approach presented in this work will help to understand the structure-property relationships of composite materials from a new perspective.

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Diabetic patients are at high risk of developing delayed cutaneous wound healing. Proper keratinocyte proliferation and migration are crucial steps during re-epithelialization. Melatonin (Mel) accelerates wound repair in full-thickness incisional wounds; however, its role in diabetic wound healing is unknown. This study explored the role of Mel in diabetic wound healing in vitro by using high glucose (HG)-cultured keratinocytes. Mel reduced the HG-induced mRNA expression and release of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin (IL)-1ß, IL-6, and IL-8, in keratinocytes. Mel inhibited oxidative stress, as evidenced by reduced production of reactive oxygen species and malondialdehyde and increased activity of superoxide dismutase in HG-stimulated keratinocytes. Mel also inhibited HG-induced nucleotide binding oligomerization domain-like receptor family pyrin domain-containing 3 inflammasome activation in keratinocytes. HG-induced reduced migration and proliferation and increased apoptosis of keratinocytes were counteracted by Mel treatment. The pro-proliferative, pro-migratory, and anti-apoptotic effects of Mel on HG-treated keratinocytes were mediated by extracellular signal-regulated kinase signaling pathway. Results collectively suggested that Mel is an alternative therapeutic strategy to ameliorate poor condition for diabetic wound healing by regulating keratinocyte activity.

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Affected by the height dependent effects, the phase-shifting shadow moiré can only be implemented in an approximate way. In the technique, a fixed phase step around π/2 rad between two adjacent frames is usually introduced by a grating translation in its own plane. So the method is not flexible in some situations. Additionally, because the shadow moiré fringes have a complex intensity distribution, computing the introduced phase shift from the existing arccosine function or arcsine function-based phase shift extraction algorithm always exhibits instability. To solve it, we developed a Gram-Schmidt orthonormalization approach based on a three-frame self-calibration phase-shifting algorithm with equal but unknown phase steps. The proposed method using the arctangent function is fast and can be implemented robustly in many applications. We also do optical experiments to demonstrate the correction of the proposed method by referring to the result of the conventional five-step phase-shifting shadow moiré. The results show the correctness of the proposed method.