Search

Due to the performance degradation of liner systems, landfill leachate may significantly increase over the long term, and ignorance of this may lead to a serious underestimation of a landfill's emissions and associated environmental impact during its life cycle. This paper examined the long-term behavior of HDPE geomembranes under field conditions using analytical and mechanical tests as well as the geoelectric leak location method. The aging information obtained, together with site-specific meteorological and hydrogeological data and landfill design parameters, were then used in the LandSim and HELP models to perform quantitative analyses of leachate production, emission, and environmental impacts on groundwater. The results demonstrated that the HDPE geomembranes reaches its service life after 8 years of landfill operation, beyond which its hydraulic performance begins to degrade rapidly. This results in leachate leakage increasing from an initial level of 0.05–0.6 m3/d to a long-term range of 27.4–37.6 m3/d. This is accompanied by changes to its impact on groundwater, with the impact extent expanding from 50 to 1000 m and pollution probability going from "almost impossible" to "almost certain". The above results remind us to take measures to control the aging process of HDPE geomembranes in landfill environments in order to extend their service life. Moreover, it also suggests that we should consider the long-term emissions of landfills as well as the impact of secondary waste disposal when conducting landfill life cycle assessment. • HDPE GM life in filed condition is 10–300 times shorter than that expected ideally. • Results in a drastic increase in leachate leakage from 0.05 to 0.6 to 27.4–37.6 m3/d. • Indicates emissions in its EOL accounting for a large proportion in its life cycle. [ABSTRACT FROM AUTHOR]

The topological phase of matter, originally proposed and first demonstrated in fermionic electronic systems, has drawn considerable research attention in the past decades due to its robust transport of edge states and its potential with respect to future quantum information, communication, and computation. Recently, searching for such a unique material phase in bosonic systems has become a hot research topic worldwide. So far, many bosonic topological models and methods for realizing them have been discovered in photonic systems, acoustic systems, mechanical systems, etc. These discoveries have certainly yielded vast opportunities in designing material phases and related properties in the topological domain. In this review, we first focus on some of the representative photonic topological models and employ the underlying Dirac model to analyze the edge states and geometric phase. On the basis of these models, three common types of two-dimensional topological photonic systems are discussed: 1) photonic quantum Hall effect with broken time-reversal symmetry; 2) photonic topological insulator and the associated pseudo-time-reversal symmetry-protected mechanism; 3) time/space periodically modulated photonic Floquet topological insulator. Finally, we provide a summary and extension of this emerging field, including a brief introduction to the Weyl point in three-dimensional systems. [ABSTRACT FROM AUTHOR]

Di-(2-ethylhexyl)-phthalate (DEHP) is causing serious health hazard in wildlife animal and human through environment and food chain, including the effect of brain development and impacted neurobehavioral outcomes. However, DEHP exposure caused cerebellar toxicity in bird remains unclear. To evaluate DEHP-exerted potential neurotoxicity in cerebellum, male quails were exposed with 0, 250, 500 and 750 mg/kg BW/day DEHP by gavage treatment for 45 days. Neurobehavioral abnormality and cerebellar histopathological alternation were observed in DEHP-induced quails. DEHP exposure increased the contents of total Cytochrome P450s (CYPs) and Cytochrome b5 (Cyt b5) and the activities of NADPH-cytochrome c reductase (NCR) and aniline-4-hydeoxylase (AH) in quail cerebellum. The expression of nuclear xenobiotic receptors (NXRs) and the transcriptions of CYP enzyme isoforms were also influenced in cerebellum by DEHP exposure. These results suggested that DEHP exposure caused the toxic effects of quail cerebellum. DEHP exposure disrupted the cerebellar CYP enzyme system homeostasis via affecting the transcription of CYP enzyme isoforms. The cerebellar P450arom and CYP3A4 might be biomarkers in evaluating the neurotoxicity of DEHP in bird. Finally, this study provided new evidence that DEHP-induced toxic effect of quail cerebellum was associated with activating the NXRs responses and disrupting the CYP enzyme system homeostasis. [ABSTRACT FROM AUTHOR]