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The Belt and Road Initiative (BRI) is a central policy within China's regional development and foreign trade strategy. Traditional trade has typically depended on economic valuation of resources, while the embedded environmental value is rarely considered. This situation exists in most BRI trade evaluations. To address BRI environmental sustainability issues, we consider the role of pivotal Chinese provinces and their key trade partners (ASEAN countries) as an illustration for the environmental value of resource exchanges. Emergy accounting is used as the valuation tool for a sample period of seventeen years. Key results include: (1) Emergy valuations show sustainability of sample provinces decreased over time; (2) ASEAN countries such as Indonesia, Malaysia, Singapore, Thailand, and Vietnam play significant resource roles for provincial economic systems; (3) Diverse trends in trade between pivotal provinces and ASEAN countries resulted in an unbalanced trade structure from trade. Policy implications are proposed to promote a more globally sustainable and fair trade using BRI as an established trade policy.

Tantalum is not only one of the critical metals applied in various advanced industries such as electronics, aerospace, military, and medical applications, but also is considered a conflict mineral, posing a threat to its global supply security. China plays a significant role in the tantalum industrial chain; however, the complete picture of its anthropogenic tantalum cycle remains unknown. This study investigates the tantalum cycles in China from 2000 to 2021 by conducting a dynamic material flow analysis. The results reveal that China's domestic tantalum consumption surged from 91 tons in 2000 to 580 tons in 2021. China heavily relied on importing tantalum minerals to support its domestic production, with a trade dependence rate of 90 %. Moreover, the trade volume of tantalum-related commodities experienced substantial growth from 2000 to 2014 and then fluctuated, with tantalum concentrates as the primary imported goods and electronic products as the primary exported goods. Approximately 24.9 % of the overall tantalum demand was met with secondary tantalum, in which 80 % of such secondary material being recovered during the refining and production stages. Policy recommendations are proposed accordingly, including diversifying tantalum mineral resources and increasing the recovery rates from end-of-life products. These policies can significantly contribute to achieving sufficient tantalum supply and maintaining sustainable tantalum supply chain in China.

Manganese is a strategic metal that has been widely applied in the steelmaking industry and the emerging energy batteries industry. China is the largest manganese importer and consumer, but the critical features of its manganese metabolisms, including its supply and demand, trade, and waste management, remain unclear. By applying dynamic material flow analysis (DMFA) method, this research investigates the evolution of China’s anthropogenic manganese flows and stocks during the period of 2000 to 2021. We found that the demand for manganese had increased almost tenfold in China from 2000 to 2021, mainly used for steelmaking, while the surging demand for manganese in energy batteries had gradually increased. However, China highly relied on importing manganese concentrates due to its limited manganese resources. The cumulative in-use manganese stocks also increased by tenfold and reached approximately 168 million tons (Mt). In addition, manganese flow from the end-of-life (EoL) final products reached 12 Mt in 2021, but few of them were recycled, implying a huge recycling potential. These findings provide valuable insights to prepare more appropriate manganese resource management policies, such as improving domestic mining technologies, enhancing manganese recycling, and diversifying the supply of manganese resources, so that the overall manganese resource efficiency can be improved.

Abstract Multiple emulsions are usually stabilized by amphiphilic molecules that combine the chemical characteristics of the different phases in contact. When one phase is a liquid crystal (LC), the choice of stabilizer also determines its configuration, but conventional wisdom assumes that the orientational order of the LC has no impact on the stabilizer. Here we show that, for the case of amphiphilic polymer stabilizers, this impact can be considerable. The mode of interaction between stabilizer and LC changes if the latter is heated close to its isotropic state, initiating a feedback loop that reverberates on the LC in form of a complete structural rearrangement. We utilize this phenomenon to dynamically tune the configuration of cholesteric LC shells from one with radial helix and spherically symmetric Bragg diffraction to a focal conic domain configuration with highly complex optics. Moreover, we template photonic microparticles from the LC shells by photopolymerizing them into solids, retaining any selected LC-derived structure. Our study places LC emulsions in a new light, calling for a reevaluation of the behavior of stabilizer molecules in contact with long-range ordered phases, while also enabling highly interesting photonic elements with application opportunities across vast fields.

Lithium-ion battery (LIB) is the key technology for climate change mitigation. The sustainability of LIB supply chain has caused widespread concern since the material utilization efficiency of LIB supply chain has not been well investigated. This study aims to fill this research gap by conducting a dynamic material flow analysis of lithium in China from 2015 to 2021. Results indicate that within the temporal boundary, lithium flow and in-use stock grew significantly in China due to the rapid development of the EV market, with lithium flow in domestic production of basic chemicals increasing by 614% to 100 kt, end-use consumption increasing by 160% to 35 kt, and in-use stock increasing by 62% to 195 kt. China has been a net importer of lithium, of which cumulative imports and exports were 343 kt and 169 kt, respectively. In addition, 103 kt of lithium was converted to inventories or was lost during the processing from 2015 to 2021. By optimizing inventory and processing, developing substitutes for lithium for non-battery applications, and improving lithium recycling, China's net import dependency of lithium could be reduced from 27%-86% to 0%-16%. Our study demonstrates that it is urgent to improve material utilization efficiency so that the lithium resource supply can be secured.

Nickel is deemed as one of the critical metals because it is currently essential in making both stainless steel and lithium-ion batteries. It is therefore critical to evaluate such impacts so that appropriate mitigation measures can be taken. Emergy is an effective evaluation method, which is widely used for environmental accounting. This study applies such an emergy-based method to evaluate nickel production in China so that the holistic environmental performance of nickel production can be examined. Typical products are chosen for different processes by considering both quantity and the development potential. Results show that nickel production is unsustainable and the associated environmental costs are not fully covered in the nickel prices. In addition, we find that environmental loading from nickel recycling is less than that from primary nickel production. Several policy recommendations are then raised based upon these results to facilitate sustainable nickel management in China.

Clean energy can lead to significant health benefits. Making it accessible throughout the world can address many ills. We delve deeply into one example—the transition toward clean residential heating and its relationship to health benefits—in China. We find that the health benefits can outweigh costs from energy expenses in northern provinces. Low-income households enjoy larger health benefits but also experience a higher expense increase, suggesting that extra subsidies or stimuli are needed to help them benefit from clean energy. Our findings suggest that clean energy transitions should be promoted in developing economies due to improved social health, lessened medical costs, and significant environmental improvements.

Summary: Characterizing material flows and environmental impacts of plastic value chain is crucial for sustainable plastic management. Here, we combine material flow analysis and life cycle assessment methods to map the flows of eight major plastics and investigate the multiple environmental impacts of China’s plastic value chain. We find that packaging and textile sectors dominate plastic consumption and are responsible for the value chain environmental burdens, but with low recycling rates. Major environmental impacts are generated in plastic production and product manufacturing stages because of the consumption of coal-based feedstocks and electricity. We therefore set up six scenarios by considering carbon neutrality energy pathway, plastic recycling improvement, and technology updating, finding that the value chain environmental impact can be reduced by 14%–57% in 2060 under combined scenario. Particularly, carbon neutrality renewable energy pathway plays an important role. These findings provide valuable insights to identify key mitigation pathways for plastic value chain.

Cholesteric Spherical Reflectors (CSRs) are omnidirectional retroreflectors that are selective in circular polarization and wavelength, enabling human-invisible fiducial markers for applications in robotics, augmented reality, anti-counterfeiting, circular economy and more

Abstract Cylindrically symmetric cholesteric liquid crystal elastomer (CLCE) fibers templated by tubular confinement are reported, displaying mechanochromic, thermochromic, and thermomechanical responses. The synthesis inside a sacrificial tube secures radial orientation of the cholesteric helix, and the ground state retroreflection wavelength is easily tuned throughout the visible spectrum or into the near‐infrared by varying the concentration of a chiral dopant. The fibers display continuous, repeatable, and quantitatively predictable mechanochromic response, reaching a blue shift of more than −220 nm for 180% elongation. The cylindrical symmetry renders the response identical in all directions perpendicular to the fiber axis, making them exceptionally useful for monitoring complex strains, as demonstrated in revealing local strain during tying of different knots. The CLCE reflection color can be revealed with high contrast against any background by taking advantage of the circularly polarized reflection. Upon heating, the fibers respond—fully reversibly—with red shift and radial expansion/axial contraction. However, there is no transition to an isotropic state, confirming a largely forgotten theoretical prediction by de Gennes. These fibers and the easy way of making them may open new windows for large‐scale application in advanced wearable technology and beyond.

Wastewater treatment plants (WWTPs) are significant contributors to energy consumption and anthropogenic greenhouse gas (GHG) emissions. For achieving carbon reduction in the wastewater treatment industry, the direct and indirect GHG emissions generated by WWTPs need to be understood from a holistic perspective. This study estimated GHG emissions from WWTPs at the country scale by integrating process-based life cycle assessment and statistical data. On-site data were collected from 17 WWTPs of various regions in China. Uncertainty analysis based on Monte Carlo was also performed, so as to provide more reliable results. The results show that life cycle GHG emissions generated from the wastewater treatment process vary from 0.29 kg CO2 eq/m3 to 1.18 kg CO2 eq/m3 based on 17 sample WWTPs. The key factors contributing to overall GHG emissions are also identified as carbon dioxide (fossil) and methane (fossil) to air mainly generated from electricity generation, and methane (biogenic) and nitrous oxide (biogenic) to air mainly generated from wastewater treatment. National average GHG emissions was evaluated with the value of 0.88 kg CO2 eq/m3, with on-site GHG emissions and off-site electricity-based GHG emissions accounting for 32% and 34%, respectively. The total GHG emissions generated from wastewater treatment are 56.46 billion kg CO2 eq in 2020, with Guangdong province having the dominant contribution. Policy suggestions (e.g., further adjusting the electricity grid toward a low carbon structure, improving technology to promote treatment efficiency and energy recovery) were highly recommended so that national GHG emissions of WWTPs can be reduced. In order to achieve the synergy of pollutant removal and GHG emission reduction, policy-making on wastewater treatment should be tailored to specific local conditions.

Phosphorus (P) is an essential element for supporting our life and is a non-renewable resource. This study applied dynamic material flow analysis to elucidate the phosphorus flow characteristics in China over the period from 1990–2019. Based on this, we developed a P resource efficiency index system and further explored the potential reasons for the changes in different areas by analyzing the inflow, outflow, and reuse of P in various modules. Results show that the phosphorus utilization efficiency (PUE) in crop planting increased from 63% in 1990 to 72% in 2019, while this figure in feeding livestock increased from 35% in 1990 to 42% in 2019 due to the utilization of straw. The figure in aquaculture remained low at 9% in 2019. The total P amount used for human consumption increased to 2562 Gg in 2019 due to changes in dietary habits, and the overall P recycling rate (PRR) for various human activities jumped to 58% in 2019. Based upon these results, several policy suggestions are proposed from governance, technology, and economic instruments perspectives.

While structural color is a powerful means of obtaining saturated and durable pigments that minimize absorption, scattering, and negative environmental impact, appearing naturally in animals and plants as well as in carefully designed artificial composites, it is fundamentally limited to spectral colors, leaving white and other mixed colors elusive. It also normally suffers from a strong viewing angle dependence, making color definition difficult. Herein, it is demonstrated that these challenges can be overcome by using cholesteric spherical reflectors (CSRs), spheres of polymerized cholesteric liquid crystal with radial alignment of the self‐assembled helical structure. Exhibiting omnidirectional selective retroreflectivity of well‐defined color, CSRs are discrete “packages” of structural color. This allows them to be used as pixels for generating nonspectral colors, following the principle of digital displays. A method of creating densely packed monolayers of CSRs with red (R), green (G), and blue (B) retroreflection is developed. Mixing them in equal proportions gives a white surface. By embedding the CSRs in an index matching transparent medium, nonselective specular reflections and scattering are avoided. The approach can be used to create arbitrary colors, including nonspectral ones, without any absorption or nonselective scattering, opening doors to decorating surfaces as desired while minimizing light loss.

China has set up its ambitious carbon neutrality target, which mainly relies on significant energy-related carbon emissions reduction. As the largest important contributing sector, power sector must achieve energy transition, in which critical minerals will play an essential role. However, the potential supply and demand for these minerals are uncertain. This study aims to predict the cumulative demand for critical minerals in the power sector under different scenarios via dynamic material flow analysis (DMFA), including total demands, supplies and production capacities of different minerals. Then, these critical minerals are categorized into superior and scarce resources for further analysis so that more detailed results can be obtained. Results present that the total minerals supply will not meet the total minerals demand (74260 kt) in 2060. Serious resource shortages will occur for several key minerals, such as Cr, Cu, Mn, Ag, Te, Ga, and Co. In addition, the demand for renewable energy will be nearly fifty times higher than that of fossil fuels energy, implying more diversified demands for various minerals. Finally, several policy recommendations are proposed to help improve the overall resource efficiency, such as strategic reserves, material substitutions, and circular economy.

Kerr frequency combs are a promising laser source for future optical networks. The authors demonstrate coherence-cloning between two remote Kerr combs and improve optical coherent communication in terms of performance, power consumption, and simplicity.

The growing water scarcity due to international trade poses a serious threat to global sustainability. Given the intensified international trade throughout the Belt and Road Initiative (BRI), this paper tracks the virtual water trade and water footprint of BRI countries in 2005–2015. By conducting a multi-model assessment, we observe a substantial increase in BRI's water footprint after taking water scarcity into account. Globally the BRI acts as a net exporter of virtual water, while the export volume experiences a decreasing trend. Noticeable transitions in nations' role (net exporters vs. net importers) are found between the BRI and global scales, but also between with and without considering water scarcity. Overall economic and population growth is major drivers of scarcity-weighted water footprint for BRI nations, as opposed to the promotion of water-use efficiency and production structure that can reduce water scarcity. Improving international trade and strengthening cooperation on water resources management deserve priority in alleviating the water scarcity of BRI.

Abstract Invasive lobular carcinoma (ILC) has a greater tendency to metastasize to the peritoneum, retroperitoneum, and gastrointestinal (GI) tract as compared to invasive carcinoma of no special type (NST). Like primary ILC in the breast, ILC metastases are frequently infiltrative and hypometabolic, rather than mass forming and hypermetabolic in nature. This renders them difficult to detect on conventional and metabolic imaging studies. As a result, intra-abdominal ILC metastases are often detected late, with patients presenting with clinical complications such as liver failure, hydronephrosis, or bowel obstruction. In patients with known history of ILC, certain imaging features are very suggestive of infiltrative metastatic ILC. These include retroperitoneal or peritoneal nodularity and linitis plastica appearance of the bowel. Recognition of linitis plastica on imaging should prompt deep or repeat biopsies. In this pictorial review, the authors aim to familiarize readers with imaging features and pitfalls for evaluation of intra-abdominal metastatic ILC. Awareness of these will allow the radiologist to assess these patients with a high index of suspicion and aid detection of metastatic disease. Also, this can direct histopathology and immunohistochemical staining to obtain the correct diagnosis in suspected metastatic disease.

Summary: Diets have important but often complex implications for both environmental quality and nutrition. We establish a production-oriented life cycle model to quantify and compare the farm-to-gate environmental impacts and food nutritional qualities underlying rural and urban diets in China from 1980 to 2019, a period of rapid urbanization and socioeconomic changes. The environmental impacts of rural diets were generally higher than those of urban diets, but this gap reduced after 2000. Environmental and nutritional values varied considerably across the 31 Chinese provinces due to their different food intakes and dietary structures. Dietary changes coinciding with urbanization increased greenhouse gas emissions, eutrophication potential, and nutritional quality, but decreased energy consumption and acidification potential. Based on our results, we propose a new dietary guideline to mitigate environmental impacts and improve nutritional quality.

Aluminium is one widely used metal that plays an important role in China's industrial and economic development. The life cycles of aluminium products involve high energy inputs, intensive material consumption and heavy environmental emissions. China has released its ambitious climate change targets, namely reaching carbon peak in 2030 and achieving carbon neutrality in 2060. It is therefore urgent to take appropriate actions to reduce the overall greenhouse gas emissions from aluminium production and increase resource efficiency along the entire aluminium life cycle. Under such circumstances, this study aims to explore China's aluminium recycling potential through dynamic material flow analysis for the period of 2000–2019, covering its whole life cycle and including relevant international trade activities. An entropy analysis method is also applied to identify optimal pathways to improve aluminum resource efficiency and circularity. Results indicate that China has experienced fast growth of aluminum production and consumption during the last two decades, with its output of primary aluminium increasing from 4.18 Mt in 2000 to 35.11 Mt in 2019 and its aluminium consumption increasing from 2.99 Mt in 2000 to 32.5 Mt in 2019. Such rapid growth has resulted in significant environmental impacts. For instance, environmental loss of aluminium at the production stage accounted for 46% of the total loss throughout its entire life cycle in 2000, while such a rate increased to 69% in 2019. As such, entropy analysis results reflect that at the stage of waste management, the relative entropy of aluminium is rising, which indicates that any pollutants discharged into the environment will cause significant damage. Scenarios analysis results further help to identify the optimal pathway of aluminium metabolism system. Finally, several policy recommendations are proposed to improve the overall aluminium resource efficiency.

Circular economy is recognized as a powerful integrative framework envisioned to solve societal problems linked to environmental pollution and resource depletion. Its adoption is rapidly reforming manufacturing, production, consumption, and recycling across various segments of the economy. However, circular economy may not always be effective or even desirable owing to the spatiotemporal dimensions of environmental risk of materials, and variability of global policies. Circular flows involving toxic materials may impose a high risk on the environment and public health such that overemphasis on anthropogenic circularity is not desirable. Moreover, waste flows at a global scale might result in an uneven distribution of risks and costs associated with a circular economy. Among other benefits, circular economy needs to generate environmental advantages, energy savings, and reductions of greenhouse gas emissions. Recent attempts to implement the carbon neutrality strategy globally will likely push the circular economy further into more economic sectors, but challenges remain in implementing and enforcing international policies across national boundaries. The United Nations Basel Convention on the Transboundary Movement of Hazardous Waste and their disposal is used here as an example to illustrate the challenges and to propose a way forward for anthropogenic circularity.

We demonstrate a phase-sensitive and amplification-based all-optical phase regenerator by utilizing on-chip Kerr soliton combs. In the experiment, we demonstrate the direct generation of a Kerr soliton comb in a silicon nitride micro-ring at the receiver side of optical communication systems by applying the transmitted signal as a pump light. The mutual coherence between the signal and the regenerated Kerr comb is excellent, and the all-optical phase regeneration of a 20 GBaud/s QPSK signal is achieved. In contrast to the traditional scheme, our solution shows better SWaP (size, weight, and power) factors. Our study will enhance the relay and reception performance of all-optical communication systems.

In order to achieve China’s ambitious carbon neutrality target, coal industry should play a key role in mitigating its carbon emission and ensuring energy supply. Therefore, it is urgent for this coal industry to realize its transition toward low carbon development. This study investigates the status and policy options of China’s coal industry by considering the entire coal industrial chain, covering coal production, delivery, and consumption so that key challenges involving clean and efficient utilization and stable coal supply can be identified. Further, policy recommendations for the transition of this coal industrial chain toward low carbon development are proposed, including the implementation of appropriate national policies, research and development (R&D) efforts, the application of economic instruments and capacity building activities.

Rare earth elements (REEs) are essential for promoting clean energy technologies and making high-performance materials because of their unique physical and chemical properties. In order to respond to climate change, the Chinese government has promised to achieve carbon neutrality before 2060. Under such a circumstance, the demand for REEs will increase significantly. However, several challenges exist in current REEs supply chain management in China. This policy brief discusses these challenges from a life cycle perspective, covering REEs mining, smelting, manufacturing, waste management, and recycling. Policy recommendations on future REEs supply chain management are then proposed, including adequate mining quota, a strategic REEs list, innovative high-tech applications, and circular economy.

Summary: The rapid spread of COVID-19 had a negative impact on public health and economic recovery worldwide. There is a large and growing literature on pandemic prevention and control. However, these existing studies seldom focus on the role of sustainable social development in this process. By setting specifications of fixed-effect models based on the score data of sustainable development goals (SDG) and infection case data from 257 Chinese cities, we evaluate the positive effect of sustainable social development on pandemic control. Our results show that sustainable social development leads to a remarkable improvement in pandemic prevention and control, especially for SDG4 (Quality Education) and SDG5 (Gender Equality). Significant positive effects of sustainable social development still exist in the post-pandemic era. This study highlights the importance of promoting social SDGs by linking them with pandemic prevention and control and suggests region-specific policies based on the heterogeneous analysis results.

Assessment of anthropocentric watersheds’ sustainability and its driving forces is important for regional natural resources management and sustainable development. However, the impact of natural resources use on watersheds’ sustainability needs deeper exploration. This study employs emergy accounting and decomposition analysis methods to evaluate the sustainability and related key factors of Erhai Lake Basin (ELB) of Yunnan province in China -- a watershed facing urgently sustainable issues. Major results show that the environmental sustainability index (ESI) of ELB decreased with low production efficiency -- emergy yield ratio (EYR), and high environmental pressure -- environmental loading ratio (ELR) from 2000 to 2015. Four factors within the decomposition analysis have been identified, namely the emergy intensity factor (ΔUG), resource factor (ΔRF), water supporting factor (ΔWN) and water efficiency factor (ΔPW), as the major drivers of ESI changes. The economic development in ELB highly exceeded the carrying capacity of natural water resources, relying on imported resources and, in so doing, affecting sustainability levels. Accordingly, several suggestions are proposed which are helpful for sustainable watersheds governance.

The Iron and Steel Industry (ISI) is a difficult-to-mitigate sector that has considerable contributions to energy consumption, water pollution, and CO2 emissions. Despite broad interest in energy consumption and CO2 emissions generated by steel production, there are few impact-oriented Water Footprint (WF) assessments of steel production. This study evaluates the water, carbon and fossil energy footprints generated from rolled steel production on the basis of life cycle assessment. Key contributors attributing to those environmental impacts are also identified so as to explore their potential mitigation. Using the Monte Carlo model, an uncertainty analysis is conducted with the aim of providing reliable results for decision-making. Results show that the impact per ton China’s rolled steel production has on global warming, human health, ecosystem quality, and resources is 4.40 × 103 kg CO2 eq (GSD2 = 1.24), 4.15 × 10-3 Disability Adjusted of Life Years (DALY) (GSD2 = 1.31), 7.08 × 10-5 Species·yr (GSD2 = 2.04), and 4.39 × 104 MJ (GSD2 = 1.28), respectively. Global warming and freshwater ecotoxicity is the dominant contributor to the damage impact on human health and ecosystem quality, respectively. Results also show that the transport (freight ship) of raw materials and the production of iron powder are the two main contributors to the overall impact on the environment that rolled steel production has. Several policy recommendations are proposed in this paper, which focus on adjusting the steel industry’s industrial structure, promoting the national-level carbon emissions trading in the ISI, promoting international cooperation, and improving public awareness of green and low-carbon development. Such policy recommendations provide decision-makers with valuable insights, which thus allow them to prepare the appropriate mitigation policies.

Recycling steel scraps by the use of electric arc furnace is one of the most promising approaches for the steel industry to achieve net-zero emissions. Due to the uneven distribution of global steel scraps, many countries are actively involving in the global steel scraps trade. Steel scraps contain a range of critical elements, which may be transferred across borders through international trade of steel scraps. However, existing studies have paid little attention to the global flows of steel scraps and its embodied alloy elements (AEs). This study maps the journey of global steel scraps and the embodied AEs for the period of 2000–2021 for the first time by employing trade-linked material flow analysis and social network analysis. The results indicate that the global steel scraps trade had increased during the study period, with a few core countries (such as USA, Germany, and Turkey) leading the global steel scraps network. Also, critical metals had been transferred across borders in the form of AEs through the trade of steel scraps, especially from global north countries to global south countries. The largest AE flows include Chromium (Cr), nickel (Ni), manganese (Mn) and molybdenum (Mo) flows. Other AE flows, such as cobalt (Co), vanadium (V), and niobium (Nb) flows, were less, but with high values or being regarded scarce. From a global perspective, steel scraps trade and recycling can contribute to the decarbonization efforts of the global steel industry and address resource shortages in some countries. Therefore, it is urgent to promote the overall resource efficiency of steel scraps and the embodied AEs by various efforts.

Energy efficient lights, such as fluorescent lamps (FLs) and light-emitting diode (LED) lamps, can greatly help energy saving, which is critical for achieving carbon neutrality in the building sector. Yttrium, europium, and terbium are three essential rare earth elements (REEs) for energy efficient lighting. However, due to the ongoing lighting technology transition from FLs to LED lamps, the demands for yttrium, europium, and terbium have decreased significantly. It resulted in oversupplies of these three REEs in the lighting sector, indicating an economically and environmentally unsustainable supply chain. This study aims to estimate the supply and demand dynamics of yttrium, europium, and terbium in China from 2021 to 2060 under China’s carbon neutrality target by applying a dynamic-material-flow-analysis framework. Key flows and stocks along their life cycles are examined. Results show that the annual demands for yttrium, europium, and terbium in China’s lighting sector will decrease by 87%–100% from 2021 to 2060 under two demand scenarios. Driven by the demands for other co-produced critical REEs, the overall growing REEs supply will result in high surplus risks of yttrium and europium. Meanwhile, terbium deficit risk deserves more attentions due to its demand growth in other fields. Such surpluses of these three REEs in 2060 under six combined demand and supply scenarios are estimated to reach between 71 727 tonnes and 274 869 tonnes for yttrium, 530 tonnes and 1712 tonnes for europium, and −1360 tonnes (i.e. deficit) and 540 tonnes for terbium. Recycling activities of major co-produced REEs, such as neodymium, and the export expansion of surplus products can effectively mitigate such surplus risks. Finally, policy recommendations are proposed to improve the overall REEs efficiency by addressing the supply–demand imbalance and mitigating corresponding environmental impacts.

Human calcium-sensing receptor (CaSR) is a G-protein-coupled receptor that maintains Ca2+ homeostasis in serum. Here, we present the cryo-electron microscopy structures of the CaSR in the inactive and agonist+PAM bound states. Complemented with previously reported structures of CaSR, we show that in addition to the full inactive and active states, there are multiple intermediate states during the activation of CaSR. We used a negative allosteric nanobody to stabilize the CaSR in the fully inactive state and found a new binding site for Ca2+ ion that acts as a composite agonist with L-amino acid to stabilize the closure of active Venus flytraps. Our data show that agonist binding leads to compaction of the dimer, proximity of the cysteine-rich domains, large-scale transitions of seven-transmembrane domains, and inter- and intrasubunit conformational changes of seven-transmembrane domains to accommodate downstream transducers. Our results reveal the structural basis for activation mechanisms of CaSR and clarify the mode of action of Ca2+ ions and L-amino acid leading to the activation of the receptor.

Summary: Coal-fired power plants (CFPPs) are key point sources to atmospheric heavy metal (HM) emissions in China. Unevenly distributed CFPPs lead to large-scale interregional power transmission, as well as corresponding environmental emissions transfer. However, the effect of power transmission on HM reallocation remains poorly understood. Here, we traced HM (including Hg, As, Se, Pb, Cd, and Cr) emission flows through electricity transmission and regional trade and calculated China's multi-perspective electricity-related HM emissions from 2010 to 2015. Results show that in 2015, power transmission and regional trade caused 226.5 t (14% of total emissions) and 453.6 t (28%) of HM emission flows, respectively, leading to great differences in provincial HM emissions under different perspectives (e.g., Beijing's consumption-based emission was 15.5 times higher than the city's production-based emission in 2015). Our study provides valuable insights for fairly allocating provincial HM emission reduction responsibility and formulating synergistic emission mitigation strategies among regions.

Resource impacts from the electrification of transport sector in terms of heavy-duty vehicles are understudied. Here the authors find that a mass deployment of plug-in electric vehicles in the heavy-duty segment at the global level can substantially increase the lithium demand.

Water embodied in traded commodities is important for water sustainability management. This study provides insight into China's water footprint and virtual water trade using three specific water named Green, Blue and Grey. A multi-region input-output analysis at national and sectoral analysis levels from the years 1995 to 2009 is conducted. The evolution and position of China's virtual water trade across a global supply chain are explored through cluster analysis. The results show that China represented 11.2% of the global water footprint in 1995 and 13.6% in 2009. The green virtual water is the largest of China's exports and imports. In general, China is a net exporter of virtual water during this time period. China mainly imports virtual water from the USA, India and Brazil, and mainly exports virtual water to the USA, Japan and Germany. The agriculture sector and the food sector represent the sectors with both the largest import and export virtual water quantities. China's global virtual water trade network has been relatively stable from 1995 to 2009. China has especially close relationships with the USA, Indonesia, India, Canada, Mexico, Brazil and Australia. Trade relations, resource endowment and supply-demand relationships may play key roles in China's global virtual water footprint network rather than geographical location. Finally, policy implications are proposed for China's long term sustainable water management and for global supply chain management in general. Keywords: Water footprint, Global supply chain, Cluster analysis, Virtual water trade, China

Sustainable crop production is a significant challenge in China. To achieve this goal, it is necessary to evaluate environmental impacts related to the sustainable development of crop production by integrating scientific and practical indicators. Therefore, this study employed emergy and index decomposition analysis approaches to assess the environmental impacts of non-point source pollution and the overall performance of crop production in China’s 31 provinces. First, the emergy flow of emission impacts and two new indicators, the emergy sustainability index and the emergy-based pollutant-producing coefficient, were proposed to comprehensively measure crop production performance from 2012 to 2015. The results demonstrated that the environmental impacts of non-point source pollution (EIN) were predominantly attributed to total nitrogen and phosphorus contents and mulching film residuals, which substantially increased the total emergy used and reduced the sustainability of crop production in each province. The ratio of EIN plus purchased resources (F) to total emergy used (U) were consistently greater than 80% in all 31 provinces, while the ratio of local resources including the emergy of local renewable (R) and non-renewable resources (N) to the total emergy was relatively small, accounting for less than 20% in all provinces. Then, a logarithmic mean Divisia index decomposition method was applied to identify the key driving forces influencing the evolution of EIN. The decomposition analysis indicated that the economy factor had a major promoting effect on EIN growth in all provinces except Beijing and Shanghai. Intensity and technology factors had a limiting effect on EIN growth. These findings provide valuable insights for developing appropriate crop production policies that consider local conditions.

Abstract This paper examines the relationships between natural resource dependence, public education investment, and human capital accumulation. It addresses why the “blessing” of abundant natural resources often turns into a “curse” in many countries and regions, focusing on the crowding-out effect of natural resources on human capital. According to our empirical analysis of provincial panel data from China, natural resource dependence is significantly and negatively correlated with human capital accumulation. The crowding-out effect of natural resources on human capital exists only in the central and western regions of China. Our introduction of an interaction term for natural resource dependence and public education investment underscores the possibility of investing in public education to reduce the crowding-out effect of natural resource dependence on human capital. The government should utilize the income of the natural resource sector to increase investment in education to enhance local human capital.

Abstract Micro-motors driven by light field have attracted much attentions for their potential applications. In order to drive the rotation of a micro-motor, structured optical beams with orbital angular momentum, spin angular momentum, anisotropic medium, and/or inhomogeneous intensity distribution should be used. Even though, it is still challenge to increase the optical torques (OT) in a flexible and controllable way in case of moderate incident power. In this paper, a new scheme achieving giant optical torque is proposed by increasing both the force arm and the force amplitude with the assistance of a ring resonator. In this case, the optical torque doesn’t act on the target directly by the incident beam, but is transmitted to it by rotating the ring resonator connected with it. Using the finite-difference in time-domain method, we calculate the optical torque and find that both the direction and the amplitude of the torque can be tuned flexibly by modifying the frequency, or the relative phases of the sources. More importantly, the optical torque obtained here by linearly polarized beams can be 3 orders larger than those obtained using the structured beams. This opt-mechanical-resonator based optical torque engineering system may find potential applications in optical driven micro-machines.

A large population size and rapid economic growth have resulted in a huge amount of housing consumption in China. Therefore, it is critical to identify the determinants of housing carbon footprint (CF) and prepare appropriate carbon mitigation measures. By employing the IPCC accounting method, input-output analysis and the stochastic impacts by regression on population, affluence, and technology (STIRPAT) model, this study aims to study the spatio-temporal patterns and identify the driving factors of housing CF. The results show that regional disparities and urban-rural differences existed during the period 2012–2017. The results of the extended STIRPAT model show that population scale and energy consumption per unit building area are the two dominant contributors to the housing CF increments in all areas. While, family size only shows significant negative impact in eastern and western regions, the per capita disposable income only induces higher housing CF in rural areas, and energy structure had a remarkable positive impact in urban area of western region and all rural areas. Policy recommendations are proposed to mitigate the overall housing CF, including; controlling population growth and promoting urbanization benefits; encouraging green consumption; optimizing household energy consumption structure, and; enhancing residential building energy management.

The formation of dissipative cavity solitons in microresonators provides an efficient process for ultrashort pulse synthesis and mode-locking of Kerr frequency combs. However, as dissipative cavity solitons arise spontaneously from a continuous-wave pump, deterministically controlling the number of intracavity solitons remains challenging to date. In this paper, we propose an efficient yet easy way to access single cavity soliton formation in microresonators via inverse-Kelly sideband generation in Kerr comb spectrum. Our method only requires fixed-speed unidirectional pump frequency sweeping to achieve single soliton state, avoiding complex pump scanning trajectory and high frequency pump modulation. Moreover, we report on the determinacy of single-soliton generation using the proposed method; statistic analysis shows that excellent determinacy as high as 98.7% is achieved.

Global greenhouse gas (GHG) emissions can be traced to five economic sectors: energy, industry, buildings, transport and AFOLU (agriculture, forestry and other land uses). In this topical review, we synthesise the literature to explain recent trends in global and regional emissions in each of these sectors. To contextualise our review, we present estimates of GHG emissions trends by sector from 1990 to 2018, describing the major sources of emissions growth, stability and decline across ten global regions. Overall, the literature and data emphasise that progress towards reducing GHG emissions has been limited. The prominent global pattern is a continuation of underlying drivers with few signs of emerging limits to demand, nor of a deep shift towards the delivery of low and zero carbon services across sectors. We observe a moderate decarbonisation of energy systems in Europe and North America, driven by fuel switching and the increasing penetration of renewables. By contrast, in rapidly industrialising regions, fossil-based energy systems have continuously expanded, only very recently slowing down in their growth. Strong demand for materials, floor area, energy services and travel have driven emissions growth in the industry, buildings and transport sectors, particularly in Eastern Asia, Southern Asia and South-East Asia. An expansion of agriculture into carbon-dense tropical forest areas has driven recent increases in AFOLU emissions in Latin America, South-East Asia and Africa. Identifying, understanding, and tackling the most persistent and climate-damaging trends across sectors is a fundamental concern for research and policy as humanity treads deeper into the Anthropocene.

Investment is an essential engine of economic growth and a major source of China’s CO2 emission. It is therefore crucial to explore the gravity movement and decoupling state of China’s CO2 emission embodied in fixed capital formation (FCF). This study aims to estimate China’s CO2 emissions embodied in various categories of FCF by using input–output tables. The gravity model and Shapley decomposition method are used to explore the gravity movement and regional contributions for China’s CO2 emissions embodied in FCF. Then, the Tapio decoupling model and logarithmic mean Divisia index (LMDI) method are combined to uncover the decoupling relationship between CO2 emissions and economic growth embodied in FCF and the corresponding driving factors. The results show that China’s CO2 emissions embodied in FCF experienced a rapid increase during 2002–2012 and remained almost stable during 2012–2017. The gravity center for CO2 emissions embodied in FCF moved toward northwest during 2002–2015, with the northwestern region and middle Yellow River region being the main engine regions. The relations between CO2 emissions and added values embodied in various categories of FCF were weak decoupling during 2002–2017. Investment scale was the major factor inhibiting the decoupling, while embodied energy intensity was the major factor promoting the decoupling. Finally, several policy recommendations are proposed based on these findings.

In order to respond to rapid urbanization, understanding the relationships between urbanization and ecosystem services (ESs) is of practical importance to move toward sustainable urban development. In this study, an emergy-GIS based method is proposed to evaluate ESs. Spatiotemporal emergy values of water retention (WR), air purification (AP), carbon sequestration (CS), soil conservation (SC), and biodiversity conservation (BC) were quantified and relationships among these ESs were analyzed by taking China’s largest city, Shanghai, as a case. The decoupling analysis was conducted to study the relationship between urbanization and ESs. Results show that the total value of regulating ESs had declined by 8.24% from 2005 to 2010. Chongming had the largest value of ESs, followed by Pudong. There is a synergetic relationship among AP, CS, and SC, while a tradeoff appears between WR and other services. Irregular “U” shape relationships between the decrease of ESs and urbanization indicators were observed. Results from decoupling analysis show that ESs experienced weak decoupling from urbanization in most districts. Finally, policy implications were raised based on the study results.

Actions tackling with climate change can cause co-benefits and trade-offs with Sustainable Development Goals (SDGs) concerned with air pollution, water scarcity, food security, land use, and sustainable energy. Such interactions can be greatly influenced by socioeconomic conditions. The impacts of socioeconomic conditions on multiple SDGs have not been evaluated separately from climate policies. This paper employs a Representative Concentration Pathways–Shared Socio-economic Pathways (RCP-SSP) framework and the Asia-Pacific Integrated Model/computable general equilibrium (AIM/CGE) integrated assessment model to identify the global multi-sectoral consequences of socioeconomic conditions through 2050 under future SSP scenarios. Results show that changes of socioeconomic conditions consistent with the SSP1 pathway could always improve SDG indicators, with or without climate policies. In many respects, socioeconomic conditions are more important than climate policies in achieving SDGs, particularly SDGs concerned with food security and energy affordability, as well as in simultaneously achieving multiple SDGs. We conclude that the advantages of a joint effort to implement climate policies and promulgate socioeconomic changes should be recognized by policy makers.

Human calcium-sensing receptor (CaSR) is a G-protein-coupled receptor (GPCR) that maintains extracellular Ca2+ homeostasis through the regulation of parathyroid hormone secretion. It functions as a disulfide-tethered homodimer composed of three main domains, the Venus Flytrap module, cysteine-rich domain, and seven-helix transmembrane region. Here, we present the crystal structures of the entire extracellular domain of CaSR in the resting and active conformations. We provide direct evidence that L-amino acids are agonists of the receptor. In the active structure, L-Trp occupies the orthosteric agonist-binding site at the interdomain cleft and is primarily responsible for inducing extracellular domain closure to initiate receptor activation. Our structures reveal multiple binding sites for Ca2+ and PO43- ions. Both ions are crucial for structural integrity of the receptor. While Ca2+ ions stabilize the active state, PO43- ions reinforce the inactive conformation. The activation mechanism of CaSR involves the formation of a novel dimer interface between subunits.