Objective Vehicle base serves as a place for parking and maintenance of guideway rubber-tyred trams. Vehicles are traveling on complex routes and operating turn-back frequently within the base. Since ...guideway rubber-tyred trams turn-back operation in vehicle base will undermine the vehicle turnover efficiency, a vehicle base layout form that can avoid tram turn-back operation is proposed. Method The characteristics of guideway rubber-tyred tram vehicles and turnouts are introduced. The current production process and existing problems of guideway rubber-tyred tram vehicle base in China are analyzed. Combining the advantage of vehicle small turning radius and the vehicle base site selection conditions, vehicle base schemes are analyzed. A design scheme for rubber-tyred tram vehicle base without turn-back operation is developed, as well as the implementation process for scheduling vehicles without turn-back operation. When the washing garage for daily inspection is not occupied, the daily inspection, washing, an
The 17 Sustainable Development Goals (SDGs) and 169 targets under Agenda 2030 of the United Nations map a coherent global sustainability ambition at a level of detail general enough to garner ...consensus amongst nations. However, achieving the global agenda will depend heavily on successful national-scale implementation, which requires the development of effective science-driven targets tailored to specific national contexts and supported by strong national governance. Here we assess the feasibility of achieving multiple SDG targets at the national scale for the Australian land-sector. We scaled targets to three levels of ambition and two timeframes, then quantitatively explored the option space for target achievement under 648 plausible future environmental, socio-economic, technological and policy pathways using the Land-Use Trade-Offs (LUTO) integrated land systems model. We show that target achievement is very sensitive to global efforts to abate emissions, domestic land-use policy, productivity growth rate, and land-use change adoption behaviour and capacity constraints. Weaker target-setting ambition resulted in higher achievement but poorer sustainability outcomes. Accelerating land-use dynamics after 2030 changed the targets achieved by 2050, warranting a longer-term view and greater flexibility in sustainability implementation. Simultaneous achievement of multiple targets is rare owing to the complexity of sustainability target implementation and the pervasive trade-offs in resource-constrained land systems. Given that hard choices are needed, the land-sector must first address the essential food/fibre production, biodiversity and land degradation components of sustainability via specific policy pathways. It may also contribute to emissions abatement, water and energy targets by capitalizing on co-benefits. However, achieving targets relevant to the land-sector will also require substantial contributions from other sectors such as clean energy, food systems and water resource management. Nations require globally coordinated, national-scale, comprehensive, integrated, multi-sectoral analyses to support national target-setting that prioritizes efficient and effective sustainability interventions across societies, economies and environments.
Water splitting is an important source of hydrogen, a promising future carrier for clean and renewable energy. A detailed understanding of the mechanisms of water splitting, catalyzed by supported ...metal atoms or nanoparticles, is essential to improve the design of efficient catalysts. Here, we report an infrared spectroscopic study of such a water splitting process, assisted by a C60 supported vanadium atom, C60V++H2O→C60VO++H2. We probe both the entrance channel complex C60V+(H2O) and the end product C60VO+, and observe the formation of H2 as a result from resonant infrared absorption. Density functional theory calculations exploring the detailed reaction pathway reveal that a quintet‐to‐triplet spin crossing facilitates the water splitting reaction by C60‐supported V+, whereas this reaction is kinetically hindered on the isolated V+ ion by a high energy barrier. The C60 support has an important role in lowering the reaction barrier with more than 70 kJ mol−1 due to a large orbital overlap of one water hydrogen atom with one carbon atom of the C60 support. This fundamental insight in the water splitting reaction by a C60‐supported single vanadium atom showcases the importance of supports in single atom catalysts by modifying the reaction potential energy surface.
Splitting of water by a single vanadium is greatly facilitated by a C60 support, which can be regarded as a small piece of porous carbon nanomaterials, especially those with intrinsic pentagonal defects and curvatures. The compelling experimental and theoretical evidence demonstrates the important role of support in single vanadium atom catalysis.
The development of novel materials for highly efficient and selective photocatalysis is crucial for their practical applications. Herein, we employ the host‐guest chemistry of porphyrin‐based ...metallacages to regulate the generation of reactive oxygen species and further use them for the selective photocatalytic oxidation of benzyl alcohols. Upon irradiation, the sole metallacage (6) can generate singlet oxygen (1O2) effectively via excited energy transfer, while its complex with C70 (6⊃C70) opens a pathway for electron transfer to promote the formation of superoxide anion (O2⋅−), producing both 1O2 and O2⋅−. The addition of 4,4′‐bipyridine (BPY) to complex 6⊃C70 forms a more stable complex (6⊃BPY) via the coordination of the Zn‐porphyrin faces of 6 and BPY, which drives fullerenes out of the cavities and restores the ability of 1O2 generation. Therefore, benzyl alcohols are oxidized into benzyl aldehydes upon irradiation in the presence of 6 or 6⊃BPY, while they are oxidized into benzoic acids when 6⊃C70 is employed as the photosensitizing agent. This study demonstrates a highly efficient strategy that utilizes the host‐guest chemistry of metallacages to regulate the generation of reactive oxygen species for selective photooxidation reactions, which could promote the utilization of metallacages and their related host‐guest complexes for photocatalytic applications.
A Zn‐porphyrin‐based metallacage exhibited strong host‐guest interactions with fullerene derivatives. The complexes could be dissembled by the further addition of 4,4′‐bipyridine to form a more stable coordinated complex. This tunable host‐guest complexation was further employed to generate different types of reactive oxygen species, enabling the highly efficient and selective photocatalytic oxidation of benzyl alcohols.
Proton exchange membrane fuel cells (PEMFCs) with high efficiency and nonpollution characteristics have attracted massive attention from both academic and industrial communities due to their ...irreplaceable roles in building the future sustainable energy system. However, the stability issue of Pt‐based catalysts for oxygen reduction reaction (ORR) has become a central constraint to the widespread deployment of the devices relative to the catalytic activity. This review aims to provide comprehensive insights into how to improve the stability of Pt‐based catalysts for ORR. First, the basic physical chemistry behind the catalyst degradation, including the fundamental understandings of carbon corrosion, catalyst dissolution, and particle sintering, is highlighted. After a discussion of advanced characterization techniques for the catalyst degradation, the design strategies for improving the stability of Pt‐based catalysts are summarized. Finally, further insights into the remaining challenges and future research directions are also provided.
Strategies to improve the stability of Pt‐based catalysts for the oxygen reduction reaction are comprehensively reviewed. The basic physical chemistry behind the catalyst degradation is highlighted. After a discussion of advanced characterization techniques for the catalyst degradation, design strategies for improving the stability of Pt‐based catalysts are proposed.
Detection of complex organic species in space has been one of the biggest challenges of the astrophysical community since the beginning of space exploration, with C
60
-fullerene representing one of ...the largest molecules so far detected. The presence of small metal-containing organic molecules, like MgNC or CaCN, in space, promoted the idea that C
60
may also interact with metals and form metallofullerenes based on the fact that in certain circumstellar and interstellar environments, the ingredients for the formation of metallofullerenes,
i.e.
, metal and fullerenes, are abundant. In this perspective, we summarized the current effort to explore the presence of metallofullerenes in space, which started soon after the discovery of fullerenes about 40 years ago. Several implications of astrophysical phenomena were briefly discussed and shown to be addressable as the possible consequence of metallofullerenes presence. We highlighted the spectral fingerprints that might be followed to achieve the future detection of cosmic metallofullerenes from a combined effort of laboratory and quantum chemical calculations. These results are expected to gain great importance with the James Webb Space Telescope (JWST), whose capability of unprecedented high sensitivity and high spectral resolution in the far- to mid-infrared range could aid the unequivocal detection of metallofullerenes in space.
Metallofullerenes, either endo- or exo-hedral, could be potential candidates to explain several astrophysical phenomena, including unidentified infrared emission bands and diffuse interstellar bands.
Sepsis is recognized as a life-threatening organ dysfunctional disease that is caused by dysregulated host responses to infection. Up to now, sepsis still remains a dominant cause of multiple organ ...dysfunction syndrome (MODS) and death among severe condition patients. Pyroptosis, originally named after the Greek words “pyro” and “ptosis” in 2001, has been defined as a specific programmed cell death characterized by release of inflammatory cytokines. During sepsis, pyroptosis is required for defense against bacterial infection because appropriate pyroptosis can minimize tissue damage. Even so, pyroptosis when overactivated can result in septic shock, MODS, or increased risk of secondary infection. Proteolytic cleavage of gasdermin D (GSDMD) by caspase-1, caspase-4, caspase-5, and caspase-11 is an essential step for the execution of pyroptosis in activated innate immune cells and endothelial cells stimulated by cytosolic lipopolysaccharide (LPS). Cleaved GSDMD also triggers NACHT, LRR, and PYD domain-containing protein (NLRP) 3-mediated activation of caspase-1 via an intrinsic pathway, while the precise mechanism underlying GSDMD-induced NLRP 3 activation remains unclear. Hence, this study provides an overview of the recent advances in the molecular mechanisms underlying pyroptosis in sepsis.
Solid-state batteries with metallic anodes have attracted great attention due to their high energy density and safety. As an indispensable part of these batteries, solid-state electrolytes (SSEs) ...with excellent mechanical strength and non-flammability play a significant role in suppressing the growth of dendrites and eliminating the risk of short circuits, whose development could greatly promote the overall battery performance. Recently, metal-organic frameworks (MOFs), a type of porous crystalline inorganic-organic material, have shown potential for the fabrication of high-performance SSEs, which have become an emerging research direction. Benefiting from the rich porosity, controllable functionality and modularity, MOFs not only offer great opportunities for manipulating the physicochemical and electrochemical properties of SSEs, but also provide ideal platforms for investigating the underlying mechanisms of ion conduction and the structure-property relationships. In this perspective, the development of MOF-based SSEs, which include MOF-incorporated polymer hybrids, ionic liquid-laden MOF hybrids, and neat MOFs as SSEs, is outlined. By discussing the pioneering works, both the opportunities and challenges in each SSE category are presented. Additionally, some design principles for MOFs and MOF-based SSEs, as well as the future directions for further development are provided.
This perspective highlights the application of MOFs for solid-state electrolytes, emphasizing their advantages, challenges and future directions.
Covalent organic frameworks have recently gained increasing attention in photocatalytic hydrogen generation from water. However, their structure-property-activity relationship, which should be ...beneficial for the structural design, is still far-away explored. Herein, we report the designed synthesis of four isostructural porphyrinic two-dimensional covalent organic frameworks (MPor-DETH-COF, M = H
, Co, Ni, Zn) and their photocatalytic activity in hydrogen generation. Our results clearly show that all four covalent organic frameworks adopt AA stacking structures, with high crystallinity and large surface area. Interestingly, the incorporation of different transition metals into the porphyrin rings can rationally tune the photocatalytic hydrogen evolution rate of corresponding covalent organic frameworks, with the order of CoPor-DETH-COF < H
Por-DETH-COF < NiPor-DETH-COF < ZnPor-DETH-COF. Based on the detailed experiments and calculations, this tunable performance can be mainly explained by their tailored charge-carrier dynamics via molecular engineering. This study not only represents a simple and effective way for efficient tuning of the photocatalytic hydrogen evolution activities of covalent organic frameworks at molecular level, but also provides valuable insight on the structure design of covalent organic frameworks for better photocatalysis.
The role of rivers as a major transport pathway for all sizes of plastic debris into the ocean is widely recognized. Global modelling studies ranked the Changjiang River as the largest contributor of ...plastic waste to the marine environment, but these estimates were based on insufficient empirical data. To better understand the role of rivers in delivering terrestrial plastic debris to the ocean, the spatial and temporal patterns of microplastics (MP) in the Changjiang Estuary (CE) and the East China Sea (ECS) were studied based on surface water samples in February, May, and July 2017. A total of 3225 MP (60–5000 μm) were identified by Fourier-transform infrared (FTIR) spectrometry. MP abundance in July was higher than in February and May due to higher river discharge. Density stratification in CE significantly influenced the surface MP abundances. A temporal accumulation zone within the river-sea interface for plastics was indicated by stations with apparently higher abundances in the river plume. Fibers were the most common MP (>80%) over three months. Small MP (<1000 μm) composed 75.0% of the total plastics on average. The average mass of MP was 0.000033 g/particle, which was two orders of magnitude lower than the empirical mass in literature. Without considering tidal effects, we estimate 16–20 trillion MP particles, weighing 537.6–905.9 tons, entered the sea through the surface water layer of the Changjiang River in 2017. These findings of this study provide reliable information on MP waste in a large river, which should be considered in further studies for estimating the riverine plastic loads.
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•MP abundance and size exhibited distinct seasonality in the Changjiang Estuary.•A ‘Patchiness’ in distribution of MP were observed in the Changjiang River plume.•The water density stratification impacted suspended microplastic abundances.•MP in our study averagely weighed 0.000033 g.•The annually MP load in the top layer of the Changjiang River is 537.6–905.9 tons.
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