Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have gained increasingly global attention in recent years. Due to their unique amphiphilic properties and stability, PFASs are recognized as ...highly persistent, toxic, and environmentally bioaccumulative. Among several physicochemical technologies, adsorption has been extensively used and proved to be an effective method for removing PFASs from aqueous environment. In this review article, the technical feasibility of the use of different adsorbents, such as activated carbon, ion exchange resins, minerals, molecularly imprinted polymer (MIP), carbon nanotubes (CNTs), and a wide range of potentially low-cost biosorbents, for PFASs removal from water or wastewater is critically reviewed. The evaluation and comparison of their PFASs sorption behavior in terms of kinetics and isotherms is presented. The mechanisms involved in PFASs adsorption processes, such as diffusion, electrostatic interaction, hydrophobic interaction, ion exchange and hydrogen bond, are discussed. The effects of the parameters variability on sorption process are highlighted. Based on the literature reviewed, a few recommendations for future research on PFASs adsorption are also elaborated.
Capsule: The adsorption behavior and mechanisms of perfluoroalkyl and polyfluoroalkyl substances (PFASs) on various adsorbents are reviewed.
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•Resins and CNTs exhibit higher adsorption capacity than other adsorbents.•Biosorbents have great potential for efficient PFAS removal with cost-effectiveness.•Adsorption mechanisms involve electrostatic interaction, hydrophobic interaction and ion exchange.•The environmental parameters can influence PFASs adoption performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Topological superconductors (TSCs) are unconventional superconductors with bulk superconducting gap and in-gap Majorana states on the boundary that may be used as topological qubits for ...quantum computation. Despite their importance in both fundamental research and applications, natural TSCs are very rare. Here, combining state of the art synchrotron and laser-based angle-resolved photoemission spectroscopy, we investigated a stoichiometric transition metal dichalcogenide (TMD), 2M-WS
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with a superconducting transition temperature of 8.8 K (the highest among all TMDs in the natural form up to date) and observed distinctive topological surface states (TSSs). Furthermore, in the superconducting state, we found that the TSSs acquired a nodeless superconducting gap with similar magnitude as that of the bulk states. These discoveries not only evidence 2M-WS
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as an intrinsic TSC without the need of sensitive composition tuning or sophisticated heterostructures fabrication, but also provide an ideal platform for device applications thanks to its van der Waals layered structure.
Sedation is commonly used in gastrointestinal endoscopy; however, considerable variability in sedation practices has been reported. The objective of this review was to identify and synthesize ...existing recommendations on sedation practices for routine gastrointestinal endoscopy procedures.
We systematically reviewed guidelines and position statements identified through a search of PubMed, guidelines databases, and websites of relevant professional associations from January 1, 2005 to May 10, 2019. We included English-language guidelines/position statements with recommendations relating to sedation for adults undergoing routine gastrointestinal endoscopy. Documents with guidance only for complex endoscopic procedures were excluded. We extracted and synthesized recommendations relating to: 1) choice of sedatives, 2) sedation administration, 3) personnel responsible for monitoring sedated patients, 4) skills and training of individuals involved in sedation, and 5) equipment required for monitoring sedated patients. We assessed the quality of included documents using the Appraisal of Guidelines for Research & Evaluation (AGREE) II tool.
We identified 19 guidelines and 7 position statements meeting inclusion criteria. Documents generally agreed that a single, trained registered nurse can administer moderate sedation, monitor the patient, and assist with brief, interruptible tasks. Documents also agreed on the routine use of pulse oximetry and blood pressure monitoring during endoscopy. However, recommendations relating to the drugs to be used for sedation, the healthcare personnel capable of administering propofol and monitoring patients sedated with propofol, and the need for capnography when monitoring sedated patients varied. Only 9 documents provided a grade or level of evidence in support of their recommendations.
Recommendations for sedation practices in routine gastrointestinal endoscopy differ across guidelines/position statements and often lack supporting evidence with potential implications for patient safety and procedural efficiency.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This paper proposes a real options model for evaluating renewable energy investment by considering uncertain factors such as CO2 price, non-renewable energy cost, investment cost and market price of ...electricity. A phase-out mechanism is built into the model to reflect the long-term changes of subsidy policy. We apply the proposed model to empirically evaluate the investment value and optimal timing for solar photovoltaic power generation in China. Our empirical results show that the current investment environment in China may not be able to attract immediate investment, while the development of carbon market helps advance the optimal investment time. A sensitivity analysis is conducted to investigate the dynamics of investment value and optimal timing under the changes of unit generating capacity, subsidy level, market price of electricity, CO2 price and investment cost. It is found that the high investment cost and the volatility of electricity and CO2 prices, are not conducive to attract immediate investment. Instead, increasing the level of subsidy, promoting technological progress and maintaining the stability of market are useful to stimulate investment.
•Propose real option model for evaluating renewable energy investment under uncertainty•Evaluate solar PV power generation in China by considering multiple uncertain factors•Explore the dynamics of value and optimal investment timing by sensitivity analysis
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The feed-in tariff policy is widely used to promote the development of renewable energy. China also adopts feed-in tariff policy to attract greater investment in solar photovoltaic power generation. ...This study employs real options method to assess the optimal levels of feed-in tariffs in 30 provinces of China. The uncertainties in CO2 price and investment cost are considered. A method that integrates the backward dynamic programming algorithm and Least-Squares Monte Carlo method is used to solve the model. The results demonstrate that the feed-in tariffs of 30 provinces range from 0.68 RMB/kWh to 1.71 RMB/kWh, and the average level is 1.01 RMB/kWh. On this basis, we find that the levels of sub-regional feed-in tariff announced in 2013 are no longer appropriate and should be adjusted as soon as possible. We have also identified the implications of technological progress and carbon emission trading schemes, as well as the importance of strengthening electricity transmission. It has been suggested that the Chinese government takes diverse measures, including increasing research and development investment, establishing and improving a nationwide carbon emission trading scheme and accelerating the construction of electricity-transmission infrastructure, to reduce the required feed-in tariff and promote the development of solar photovoltaic power generation.
•We estimate the optimal levels of feed-in tariffs for 30 provinces in China by using real options method.•The uncertainties in CO2 price and investment cost are considered.•The feed-in tariffs of 30 provinces range from 0.68 RMB/kWh to 1.71 RMB/kWh, and the average level is 1.01 RMB/kWh.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Cells produce an extracellular matrix (ECM) with a stereotypic organization that is important for tissue function. The insect cuticle is a layered ECM that mainly consists of the polysaccharide ...chitin and associated proteins adopting a quasi‐crystalline structure. Our understanding of the molecular mechanisms deployed during construction of the highly ordered protein–chitin ECM so far is limited. In this study, we report on the role of the chitin deacetylase 1 (LmCDA1) in the organization of the protein–chitin ECM in the migratory locust Locusta migratoria, and LmCDA1 localizes predominantly to the apical tier of the protein–chitin ECM, but it is also found in lower regions. Reduction of LmCDA1 function correlates with lower amounts of chitin and impedes conversion of chitin to chitosan by deacetylation. Establishment of the quasi‐crystalline architecture of the protein–chitin ECM is, however, independent of LmCDA1 activity, but it is dependent on another chitin deacetylase, LmCDA2, which has no detectable effects on chitin deacetylation and, as shown previously, no influence on chitin content. Our data reveal that LmCDA1 and LmCDA2 act in parallel and independently from each other in defining the dimensions of the cuticle. Both enzymes are non‐uniformly distributed within the protein–chitin matrix, suggesting a site‐autonomous function.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
To examine algino-oligosaccharide production by alginase from newly isolated Flavobacterium sp. LXA and its elicitor and antibacterial activity. Algino-oligosaccharide production from alginate was ...carried out using alginase obtained from a newly isolated Flavobacterium sp. LXA. When alginase was partially purified by dual ammonium sulfate precipitation and used for alginate degradation, the viscosity loss correlated well with the release of reducing terminals. The optimal temperature and pH for alginate degradation was 40°C and pH 7·0, respectively. When alginate was added at an initial concentration of more than 0·8%, the maximal degradation rate of alginate was obtained. Under these optimal reaction conditions and with partially purified alginase, the average degrees of polymerization (DP) of alginate-degraded products was about 6·0, which favoured algino-oligosaccharide production. The algino-oligosaccharides showed an elicitor activity stimulating the accumulation of phytoalexin and inducing phenylalanine ammonia lyase in soybean cotyledon, and antimicrobial activity on Pseudomonas aeruginosa. Algino-oligosaccharide could be degraded from alginate by the partially purified alginase and its maximal bioactivity occurred on the oligosaccharide with average DP 6·8. Algino-oligosaccharide was first reported to have elicitor and antibacterial activity and have potential as a biological agent for protection against plant or human disease.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This study evaluates grid parity in the Chinese solar PV industry by calculating the unsubsidized unit profits (UUPs) of solar PV projects in 335 Chinese cities. Furthermore, the effects of ...technological advances and various electricity price mechanisms on grid parity are explored. We consider the differences between centralized grid-connected and distributed projects. Two-factor learning curves are used to forecast technological progress and two kinds of electricity price mechanisms—government-regulated and market-based—are also brought into analyses. The results indicate the infeasibility of implementing complete grid parity regardless of the type of project. However, centralized grid-connected projects in 5 cities and distributed projects in 129 cities could implement pilot grid parity. On the whole, centralized grid-connected project has a lower benefit performance than distributed projects. Resource Zone I, which consists of Ningxia Province and several western cities in Gansu, Xinjiang and Inner Mongolia, has the best benefit performance of three resource areas. Technological advances and variations in electricity prices under both mechanisms could improve the UUPs but raising them above zero in all cities would still be impossible. The market prices of electricity under market-based mechanisms may generally have greater impacts than do government-regulated mechanisms on the benefit performances throughout the whole nation.
•Calculate the unsubsidized unit profits of solar PV projects in 335 Chinese cities.•Explore effects of technological advances and various electricity price mechanisms on grid parity.•Consider the differences between centralized grid-connected and distributed projects.•Indicate the infeasibility of implementing complete grid parity regardless of the type of project.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
HIAF (High Intensity heavy ion Accelerator Facility), a new facility planned in China for heavy ion related researches, consists of two ion sources, a high intensity Heavy Ion Superconducting Linac ...(HISCL), a 45 Tm Accumulation and Booster Ring (ABR-45) and a multifunction storage ring system. The key features of HIAF are unprecedented high pulse beam intensity and versatile operation mode. The HIAF project aims to expand nuclear and related researches into presently unreachable region and give scientists possibilities to conduct cutting-edge researches in these fields. The general description of the facility is given in this article with a focus on the accelerator design.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Multi-material processing in selective laser melting using a novel approach, by the separation of two different materials within a single dispensing coating system was investigated. 316L stainless ...steel and UNS C18400 Cu alloy multi-material samples were produced using selective laser melting and their interfacial characteristics were analyzed using focused ion beam, scanning electron microscopy, energy dispersive spectroscopy and electron back scattered diffraction techniques. A substantial amount of Fe and Cu element diffusion was observed at the bond interface suggesting good metallurgical bonding. Quantitative evidence of good bonding at the interface was also obtained from the tensile tests where the fracture was initiated at the copper region. Nevertheless, the tensile strength of steel/Cu SLM parts was evaluated to be 310±18MPa and the variation in microhardness values was found to be gradual along the bonding interface from the steel region (256±7HV0.1) to the copper region (72±3HV0.1).
•Multi-material processing was successfully implemented and demonstrated in SLM.•Bi-metallic laminates of steel/Cu were successfully produced with the SLM process.•A substantial amount of Fe and Cu diffusion was observed at the bond interface.•Good metallurgical bonding was obtained at the interface of the steel/Cu laminates.•Highly refined microstructure was obtained due to rapid solidification in SLM.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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