The construction sector represents one of the most significant sources of waste generation in the European Union (EU), with nearly one billion tonnes of construction and demolition waste annually. ...This sector also contributes a third of the annual EU greenhouse gas (GHG) emissions. Accordingly, construction represents one priority area for intervention within the EU Action Plan for the Circular Economy. Increasing resource efficiency through slowing, closing, and narrowing material and energy loops, is key to mitigating climate change. However, this review paper demonstrates that the analysis of links between circular economy solutions and climate change mitigation has been scarce, despite a recent sharp increase in related literature, with 20 articles (83%) published in 2018–2019. Slowing resource solutions have been the focus of the research and could bring up to 99% savings in GHG emissions per functional unit, where material reuse stands out as the most promising alternative. Closing resource solutions can reduce emissions by 30–50% per functional unit, but results are highly dependent on recycling efficiencies and transportation distances to recovery facilities. Solutions for narrowing resource loops can bring additional GHG savings, but they remain understudied. Despite the promising results for mitigating GHG emissions, this article argues that the circular economy solutions do not always result by default in emission reductions and that a case-by-case quantification is crucial. The implementation of these solutions should be accompanied with further methodological development, such as proper allocation procedures, accurate definition of the system boundaries and integration of forecasts.
•First review of circular economy (CE) and climate change in EU construction sector.•Slowing resource solutions have received more attention than narrowing & closing.•Material reuse is the most recommended solution to increase resource efficiency.•Significant carbon reductions can be achieved but a case-by-case analysis is needed.•Sectorial & methodological barriers must be overcome for sustainable CE application.
Primitive electronic waste (e-waste) recycling has become a growing environmental concern, and toxic heavy metals released from e-waste activities may continue to threaten the health of local people. ...To study the impact of heavy metals in people around e-waste sites, 349 people from e-waste recycling sites (exposure group) and 118 people from a green plantation (control group) were surveyed, and their urinary levels of lead (UPb), cadmium (UCd), manganese (UMn), copper (UCu), and Zinc (UZn) were assayed. Questionnaire surveys for risk factors were also performed and analyzed by using the Pearson correlation analysis. Results indicated that the levels of urinary Cd in both occupational dismantling people {GM(GSD) 0.72(0.71) ug/L} and non-occupational dismantling people {GM(GSD) 0.50(0.79) ug/L} were higher than the control group {GM(GSD) 0.27(0.85) ug/L}. Further analyses of correlations between urinary heavy metal levels and exposure factors in the exposed group revealed positive relationship between the duration of dismantling and the level of UPb (p
<
0.05). Meanwhile, rice sources from local village have a positive correlation with the level of UPb and UCd (p
<
0.01). Other factors, however, may also have influences on heavy metal burden, and not all urinary heavy metal levels can be contributed to e-waste dismantling exposure levels. Primitive e-waste recycling activities may contribute to the changes of urinary heavy metal levels and increase the health risk for those chronically working on e-waste dismantling.
•Evaluate the mental situation of college students during the epidemic•Provide a theoretical basis for psychological interventions with college students.•Provide a basis for the promulgation of ...national and governmental policies.
A COVID-19 epidemic has been spreading in China and other parts of the world since December 2019. The epidemic has brought not only the risk of death from infection but also unbearable psychological pressure. We sampled college students from Changzhi medical college by using cluster sampling. They responded to a questionnaire packet that included the 7-item Generalized Anxiety Disorder Scale (GAD-7) and those inquiring the participants’ basic information. We received 7,143 responses. Results indicated that 0.9% of the respondents were experiencing severe anxiety, 2.7% moderate anxiety, and 21.3% mild anxiety. Moreover, living in urban areas (OR = 0.810, 95% CI = 0.709 - 0.925), family income stability (OR = 0.726, 95% CI = 0.645 - 0.817) and living with parents (OR = 0.752, 95% CI = 0.596 - 0.950) were protective factors against anxiety. Moreover, having relatives or acquaintances infected with COVID-19 was a risk factor for increasing the anxiety of college students (OR = 3.007, 95% CI = 2.377 - 3.804). Results of correlation analysis indicated that economic effects, and effects on daily life, as well as delays in academic activities, were positively associated with anxiety symptoms (P < .001). However, social support was negatively correlated with the level of anxiety (P < .001). It is suggested that the mental health of college students should be monitored during epidemics.
Petroleum refining unavoidably generates large volumes of oily wastewater. The environmentally acceptable disposal of oily wastewater is a current challenge to the petroleum industry. Nowadays, more ...attention has been focused on the treatment techniques of oily wastewater. Therefore, oily wastewater treatment has become an urgent problem, and it must be explored and resolved by every oilfield and petroleum company. The development status of treatment methods was summarized from six aspects, which contains flotation, coagulation, biological treatment, membrane separation technology, combined technology and advanced oxidation process. Finally, the development and prospect of treating oily wastewater was predicted.
It is known that purely low-level saliency cues such as frequency does not lead to a good salient object detection result, requiring high-level knowledge to be adopted for successful discovery of ...task-independent salient objects. In this paper, we propose an efficient way to combine such high-level saliency priors and low-level appearance models. We obtain the high-level saliency prior with the objectness algorithm to find potential object candidates without the need of category information, and then enforce the consistency among the salient regions using a Gaussian MRF with the weights scaled by diverse density that emphasizes the influence of potential foreground pixels. Our model obtains saliency maps that assign high scores for the whole salient object, and achieves state-of-the-art performance on benchmark datasets covering various foreground statistics.
"Internet +" innovation and entrepreneurship education is a new educational concept, and it is the inherent requirement of university education reform. In this paper, we take the cultivation of ...College Students' "Internet +" innovation and entrepreneurship capabilities as the core, in-depth analysis of the major problems encountered by college students in "Internet +" innovation and entrepreneurship, and realize the profound educational reform from four levels of government, universities, enterprises and university students. Based on the evaluation index of graduate innovation and entrepreneurship education, this paper constructs an evaluation model of graduate innovation and entrepreneurship education based on analytic hierarchy process (AHP), which provides basis and reference criteria for the training and evaluation of graduate innovation and entrepreneurship education.
•A holistic 2D mesoscale cohesive element model with rate-dependent cohesive law is developed.•The dynamic tensile behaviour of concrete under high strain rate is successfully capture.•The structural ...inertial effect to the dynamic strength enhancement is purposely excluded from analysis.•Mechanisms at the material level to the DIF of concrete are discussed.•Individual contribution to DIF from material heterogeneity, material viscosity and the micro-crack inertial are identified.
This paper presents the investigation of the dynamic behaviour of concrete material under high strain rate tension using an interface approach in a mesoscale model framework. A rate-dependent cohesive constitutive description is introduced into the mesoscale framework to account for the effects of viscosity occurring in the dynamic fracture process. An algorithm is developed to insert cohesive elements throughout the mesoscale mesh grids in a concrete specimen, and to identify the cohesive element properties based on the original mesoscale structure. After parameter studies in terms of the cohesive element properties, the proposed model is validated against representative experimental data. The model is then employed to investigate the dynamic tensile behaviour of concrete under high strain rates. The underlying mechanisms of the dynamic tensile strength increase of concrete, including the influence of viscous effect from rate-dependent material description, the inertial effect from cracking and the material heterogeneity, are discussed and identified respectively. Results demonstrate that the viscous effect should be incorporated into the cohesive constitutive law to account for the Stefan effect at low and moderate strain rates and the micro-crack inertial effect only plays a significant role at a relatively high strain rate. Material heterogeneity does influence the strength enhancement under dynamic loading and the significance of this effect increases with the strain rate.
This study investigated the effect of rain-shelter cultivation on the biosynthesis of flavonoids and volatiles in grapes, with an aim of determining whether rain-shelter application could help to ...improve the sensory attributes and quality of grapes. Vitis vinifera L. Chardonnay grapes, grown in the Huaizhuo basin region of northern China, were selected within two consecutive years. A rain-shelter roof was constructed using a colorless polyethylene (PE) film with a light transmittance of 80%. Results showed that rain-shelter treatment did not affect the accumulation of soluble solids during grape maturation. However, the allocation of assimilated carbon in phenolic and volatile biosynthetic pathways varied significantly, leading to alterations in polyphenolic and volatile profiles. The rain-shelter cultivation enhanced the concentration of flavan-3-ols via the flavonoid-3'5'-hydroxylase (F3'5'H) pathway, but reduced the level of flavonols and flavan-3-ols via the flavonoid-3'-hydroxylase (F3'H) pathway. In addition, the rain-shelter cultivation significantly enhanced the synthesis of fatty acid-derived volatiles, isoprene-derived terpenoids and amino acid-derived branched-chain aliphatics, but led to a decrease in the accumulation of isoprene-derived norisoprenoids and amino acid-derived benzenoids. Principal component analysis revealed some key compounds that differentiated the grapes cultivated under open-field and rain-shelter conditions. Moreover, the effect of the rain-shelter application on the accumulation of these compounds appeared to be vintage dependent. The alteration of their profiles caused by the rain-shelter treatment was significant in the vintage that received higher rainfall, which usually took place in the first rapid growth and veraison phases.
•Concrete mesoscale model is enhanced by nonlocal treatment for mesh objective.•The model is verified and validated for both global mechanical response and local fracture process zone ...evolution.•Theoretical model relating fracture process zone and size dependent strength is proposed.•Mechanisms underlying the size effect are discussed.
A comprehensive mesoscopic investigation has been conducted into the classic topic of size effect, using notched plain concrete beams subjected to three-point bending as a test bed. The concrete beams are modelled as random heterogeneous material containing three components, coarse aggregates, mortar and the interface transition zone. Mesoscopic numerical simulations using a 2D mesoscale continuum damage-based model, enhanced by a nonlocal treatment, is used to capture the whole fracture process in concrete materials. Both global and local numerical results are then examined and verified with relevant experimental evidence from the literature. A stress field interaction theory based on the strip yield model is proposed to interpret the size effect phenomenon and the role of detailed fracture process zone features is discussed accordingly.
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•This article summarizes the significant advances achieved in the past few years on synthesis, classification, mechanism and applications of CDs and CDs-based photocatalysts to give a ...thorough summary.•CDs-derived photocatalysts are devided into pure CDs and CDs composite photocatalysts and the photocatalytic efficiencies are compared.•Various kinds of mechanism during photocatalytic process in typical systems are concluded.•Applications in the fields of degradation of organics, water splitting for H2 and O2 evolution, CO2 conversion and photocatalytic chemical reactions are also reviewed to confirm the great potential of CDs-derived photocatalysts for environmental and energy issues.
With the rapid development of science and technology, environmental pollution and energy shortage become more and more prominent. To solve these problems, photocatalytic technology is regarded as one of the most efficient methods, allowing for both pollutant degradation and energy conversion. Compared with traditional group IIVI, IIIV quantum dots (QDs), carbon dots (CDs), as a newly emerging kind of fluorescent carbon-based material, possess many excellent properties, such as high aqueous solubility, low cost, low toxicity, abundant surface functional groups and good biocompatibility. In particular, the unique up-converted photoluminescence (PL) behavior and photo-induced electron transfer ability of CDs provide the new route to achieve efficient metal-free photocatalysts. This article reviews recent progress on CDs utilized for photocatalysis from different perspectives, including the following three parts: classification and synthesis, mechanism of CDs-derived photocatalysts as well as the applications for environmental issues (up-converted PL process) and energy conversion (photo-induced electron transfer process).
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