A Tibetan art form bridges the past and present and connects cultures around the world.THANGKA,a unique form of Tibetan sacred painting,is gaining prominence globally due to its vibrant colors,exquisite craftsmanship,...A Tibetan art form bridges the past and present and connects cultures around the world.THANGKA,a unique form of Tibetan sacred painting,is gaining prominence globally due to its vibrant colors,exquisite craftsmanship,and profound religious and cultural significance.With the acceleration of globalization,this symbol of Tibetan culture that combines artistic expression with spirituality has become a bridge for cultural exchange between the East and the West.Recently,China Today spoke to Yixi Puncog,art collector and council member of the China Association for Preservation and Development of Tibetan Culture,to learn more about Thangka art,its role in international exchange,and how it is enhancing China’s cultural soft power.展开更多
Chemical exchange saturation transfer magnetic resonance imaging is an advanced imaging technique that enables the detection of compounds at low concentrations with high sensitivity and spatial resolution and has been...Chemical exchange saturation transfer magnetic resonance imaging is an advanced imaging technique that enables the detection of compounds at low concentrations with high sensitivity and spatial resolution and has been extensively studied for diagnosing malignancy and stroke.In recent years,the emerging exploration of chemical exchange saturation transfer magnetic resonance imaging for detecting pathological changes in neurodegenerative diseases has opened up new possibilities for early detection and repetitive scans without ionizing radiation.This review serves as an overview of chemical exchange saturation transfer magnetic resonance imaging with detailed information on contrast mechanisms and processing methods and summarizes recent developments in both clinical and preclinical studies of chemical exchange saturation transfer magnetic resonance imaging for Alzheimer’s disease,Parkinson’s disease,multiple sclerosis,and Huntington’s disease.A comprehensive literature search was conducted using databases such as PubMed and Google Scholar,focusing on peer-reviewed articles from the past 15 years relevant to clinical and preclinical applications.The findings suggest that chemical exchange saturation transfer magnetic resonance imaging has the potential to detect molecular changes and altered metabolism,which may aid in early diagnosis and assessment of the severity of neurodegenerative diseases.Although promising results have been observed in selected clinical and preclinical trials,further validations are needed to evaluate their clinical value.When combined with other imaging modalities and advanced analytical methods,chemical exchange saturation transfer magnetic resonance imaging shows potential as an in vivo biomarker,enhancing the understanding of neuropathological mechanisms in neurodegenerative diseases.展开更多
Hydrogen energy from electrocatalysis driven by sustainable energy has emerged as a solution against the background of carbon neutrality.Proton exchange membrane(PEM)-based electrocatalytic systems represent a promisi...Hydrogen energy from electrocatalysis driven by sustainable energy has emerged as a solution against the background of carbon neutrality.Proton exchange membrane(PEM)-based electrocatalytic systems represent a promising technology for hydrogen production,which is equipped to combine efficiently with intermittent electricity from renewable energy sources.In this review,PEM-based electrocatalytic systems for H2 production are summarized systematically from low to high operating temperature systems.When the operating temperature is below 130℃,the representative device is a PEM water electrolyzer;its core components and respective functions,research status,and design strategies of key materials especially in electrocatalysts are presented and discussed.However,strong acidity,highly oxidative operating conditions,and the sluggish kinetics of the anode reaction of PEM water electrolyzers have limited their further development and shifted our attention to higher operating temperature PEM systems.Increasing the temperature of PEM-based electrocatalytic systems can cause an increase in current density,accelerate reaction kinetics and gas transport and reduce the ohmic value,activation losses,ΔGH*,and power consumption.Moreover,further increasing the operating temperature(120-300℃)of PEM-based devices endows various hydrogen carriers(e.g.,methanol,ethanol,and ammonia)with electrolysis,offering a new opportunity to produce hydrogen using PEM-based electrocatalytic systems.Finally,several future directions and prospects for developing PEM-based electrocatalytic systems for H_(2) production are proposed through devoting more efforts to the key components of devices and reduction of costs.展开更多
Anion exchange membrane(AEM),as a kind of key membrane materials,has shown great application potential in many electrochemical fields,and remarkable progress has been made in related research in recent years.In this p...Anion exchange membrane(AEM),as a kind of key membrane materials,has shown great application potential in many electrochemical fields,and remarkable progress has been made in related research in recent years.In this paper,the research status of AEM is reviewed,including its material design,preparation method,performance optimization and application in the fields of hydrogen production by electrolytic water,fuel cell and water treatment.In terms of material design,new polymer skeleton structures are emerging to regulate the stability of ion conduction channels and membranes by introducing specific functional groups or changing the molecular chain structure.The preparation methods have been gradually expanded from the traditional solution casting method to more advanced technologies,such as interfacial polymerization and electrostatic spinning,which effectively improve the microstructure and property uniformity of the film.Performance optimization focuses on improving ion conductivity,reducing membrane swelling rate and enhancing chemical stability,and a variety of modification strategies are developed and applied.Despite the achievements made so far,there are still some challenges,such as the lack of long-term stability in highly alkaline environments.Future research needs to further explore new material systems and preparation processes in order to promote the wide application and sustainable development of AEM technology in energy,environmental protection and other fields.展开更多
Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s co...Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s constant. The solution to Dirac equation gives four, real, 2-vectors solutions ψ1=(U1D1)ψ2=(U2D2)ψ3=(U3D3)ψ4=(U4D4)where (ψ1,ψ4) are coupled via linear combinations to yield spin-up and spin-down fermions. Likewise, (ψ2,ψ3) are coupled via linear combinations to represent spin-up and spin-down anti-fermions. Here, a deeper investigation of the free fermion internal frequency is discussed, hinting to an exchange interaction between the two components of which a fermion is made of. An upper limit estimate is given to the strength of this interaction.展开更多
The Fourth Dialogue on Exchanges and Mutual Learning Among Civilisations was held in Dunhuang in Northwest China's Gansu Province on Friday,bringing together politicians,heads of international organisations,schola...The Fourth Dialogue on Exchanges and Mutual Learning Among Civilisations was held in Dunhuang in Northwest China's Gansu Province on Friday,bringing together politicians,heads of international organisations,scholars and experts to discuss the significance of exchanges and dialogues between different civilisations in a world facing many conflicts.展开更多
In his speech,Han Zheng said that exchanges and mutual learning among civilisations are important driving forces for the advancement of human civilisation as well as world peace and development.President Xi Jinping po...In his speech,Han Zheng said that exchanges and mutual learning among civilisations are important driving forces for the advancement of human civilisation as well as world peace and development.President Xi Jinping pointed out that civilisations become richer and more colourful with exchanges and mutual learning.As the futures of all countries are closely interconnected,inclusiveness,coexistence,exchanges and mutual learning among different civilisations will contribute to the common progress of humanity and promote global prosperity and development.展开更多
This study develops an analytical model to evaluate the cooling performance of a porous terracotta tubular direct evaporative heat and mass exchanger. By combining energy and mass balance equations with heat and mass ...This study develops an analytical model to evaluate the cooling performance of a porous terracotta tubular direct evaporative heat and mass exchanger. By combining energy and mass balance equations with heat and mass transfer coefficients and air psychrometric correlations, the model provides insights into the impact of design and operational parameters on the exchanger cooling performance. Validated against an established numerical model, it accurately simulates cooling behavior with a Root Mean Square Deviation of 0.43 - 1.18˚C under varying inlet air conditions. The results show that tube geometry, including equivalent diameter, flatness ratio, and length significantly influences cooling outcomes. Smaller diameters enhance wet-bulb effectiveness but reduce cooling capacity, while increased flatness and length improve both. For example, extending the flatness ratio of a 15 mm diameter, 0.6 m long tube from 1 (circular) to 4 raises the exchange surface area from 0.028 to 0.037 m2, increasing wet-bulb effectiveness from 60% to 71%. Recommended diameters range from 5 mm for tubes under 0.5 m to 1 cm for tubes 0.5 to 1 m in length. Optimal air velocities depend on tube length: 1 m/s for tubes under 0.8 m, 1.5 m/s for lengths of 0.8 to 1.2 m, and up to 2 m/s for longer tubes. This model offers a practical alternative to complex numerical and CFD methods, with potential applications in cooling tower optimization for thermal and nuclear power plants and geothermal heat exchangers.展开更多
China and Indonesia enjoy a long history of cultural and people-to-people exchanges.China’s porcelain and silk and Indonesia’s spices and wood were traded along the Maritime Silk Road since the Han Dynasty(202 BC-AD...China and Indonesia enjoy a long history of cultural and people-to-people exchanges.China’s porcelain and silk and Indonesia’s spices and wood were traded along the Maritime Silk Road since the Han Dynasty(202 BC-AD 220).During the Ming Dynasty(1368-1644),legendary Chinese explorer Zheng He brought Chinese silk,porcelain,and culture to Indonesia during his seven epic voyages.Historical sites and memories about Zheng He have been preserved in many places of Indonesia to this day.展开更多
Anion-exchange membrane water electrolysers(AEMWEs)and fuel cells(AEMFCs)are critical technologies for converting renewable resources into green hydrogen(H_(2)),where anion-exchange membranes(AEMs)play a vital role in...Anion-exchange membrane water electrolysers(AEMWEs)and fuel cells(AEMFCs)are critical technologies for converting renewable resources into green hydrogen(H_(2)),where anion-exchange membranes(AEMs)play a vital role in efficiently transporting hydroxide ions(OH^(-))and minimizing fuel crossover,thus enhancing overall efficiency.While conventional AEMs with linear,side-chain,and block polymer architectures show promise through functionalization,their long-term performance remains a concern.To address this,hyperbranched polymers offer a promising alternative due to their three-dimensional structure,higher terminal functionality,and ease of functionalization.This unique architecture provides interconnected ion transport pathways,fractional free volume,and enhanced long-term stability in alkaline environments.Recent studies have achieved conductivities as high as 304.5 mS cm^(-1),attributed to their improved fractional free volume and microphase separation in hyperbranched AEMs.This review explores the chemical,mechanical,and ionic properties of hyperbranched AEMs in AEMFCs and assesses their potential for application in AEMWEs.Strategies such as blending and structural functionalisation have significantly improved the properties by promoting microphase separation and increasing the density of cationic groups on the polymer surface.The review provides essential insights for future research,highlighting the challenges and opportunities in developing high-performance hyperbranched AEMs to advance hydrogen energy infrastructure.展开更多
Cambodia and China have long enjoyed a close relationship grounded in centuries of historical,cultural,and political ties.From their early connections in the 13th Century to today’s multifaceted partnership,the bond ...Cambodia and China have long enjoyed a close relationship grounded in centuries of historical,cultural,and political ties.From their early connections in the 13th Century to today’s multifaceted partnership,the bond between these two nations has been built on mutual respect and cooperation,fortified by economic collaboration and a profound connection between their peoples.Since the formal establishment of diplomatic ties in 1958,Cambodia and China have fostered an enduring“ironclad”friendship that weathered challenges and adapted to the everchanging global dynamics.展开更多
The China-CEEC Standardization Exchange Event on Science, Technology and Innovation was convened on December 12-13, 2024 in Yiwu, Zhejiang province.Hosted by China Science and Technology Exchange Center and held by Ch...The China-CEEC Standardization Exchange Event on Science, Technology and Innovation was convened on December 12-13, 2024 in Yiwu, Zhejiang province.Hosted by China Science and Technology Exchange Center and held by China Jiliang University (CJLU), the event was themed “standards innovation promotes high-quality development:tasks and challenges of standardization development of biomanufacturing”, which is the third event of the series of activities, China-CEEC Inno Share, in 2024.More than 150 representatives from governments, universities, research institutions and enterprises in 15 countries attended the meeting to discuss cutting-edge achievements in sci-tech innovation.展开更多
On March 5,the 2025 Cultural Exchange Activity for the Spouses of Diplomats in China themed“A Women’s Gathering.Stitching a Beautiful World”was held at EVE Castle in Beijing.This event was co-organized by the Spous...On March 5,the 2025 Cultural Exchange Activity for the Spouses of Diplomats in China themed“A Women’s Gathering.Stitching a Beautiful World”was held at EVE Castle in Beijing.This event was co-organized by the Spouses of Diplomats’Club and the Mexican Embassy in China.The wives of Ambassadors from many countries around the world have gathered in Beijing to celebrate International Women’s Day.展开更多
Geothermal energy,a form of renewable energy,has been extensively utilized for building heating.However,there is a lack of detailed comparative studies on the use of shallow and medium-deep geothermal energy in buildi...Geothermal energy,a form of renewable energy,has been extensively utilized for building heating.However,there is a lack of detailed comparative studies on the use of shallow and medium-deep geothermal energy in building energy systems,which are essential for decision-making.Therefore,this paper presents a comparative study of the performance and economic analysis of shallow and medium-deep borehole heat exchanger heating systems.Based on the geological parameters of Xi’an,China and commonly used borehole heat exchanger structures,numerical simulationmethods are employed to analyze performance and economic efficiency.The results indicate that increasing the spacing between shallow borehole heat exchangers can effectively reduce thermal interference between the pipes and improve heat extraction performance.As the flow rate increases,the outlet water temperature ranges from 279.3 to 279.7 K,with heat extraction power varying between 595 and 609 W.For medium-deep borehole heat exchangers,performance predictions show that a higher flow rate results in greater heat extraction power.However,when the flow rate exceeds 30 m^(3)/h,further increases in flow rate have only a minor effect on enhancing heat extraction power.Additionally,the economic analysis reveals that the payback period for shallow geothermal heating systems ranges from 10 to 11 years,while for medium-deep geothermal heating systems,it varies more widely from 3 to 25 years.Therefore,the payback period for medium-deep geothermal heating systems is more significantly influenced by operational and installation parameters,and optimizing these parameters can considerably shorten the payback period.The results of this study are expected to provide valuable insights into the efficient and cost-effective utilization of geothermal energy for building heating.展开更多
Quanto options allow the buyer to exchange the foreign currency payoff into the domestic currency at a fixed exchange rate. We investigate quanto options with multiple underlying assets valued in different foreign cur...Quanto options allow the buyer to exchange the foreign currency payoff into the domestic currency at a fixed exchange rate. We investigate quanto options with multiple underlying assets valued in different foreign currencies each with a different strike price in the payoff function. We carry out a comparative performance analysis of different stochastic volatility (SV), stochastic correlation (SC), and stochastic exchange rate (SER) models to determine the best combination of these models for Monte Carlo (MC) simulation pricing. In addition, we test the performance of all model variants with constant correlation as a benchmark. We find that a combination of GARCH-Jump SV, Weibull SC, and Ornstein Uhlenbeck (OU) SER performs best. In addition, we analyze different discretization schemes and their results. In our simulations, the Milstein scheme yields the best balance between execution times and lower standard deviations of price estimates. Furthermore, we find that incorporating mean reversion into stochastic correlation and stochastic FX rate modeling is beneficial for MC simulation pricing. We improve the accuracy of our simulations by implementing antithetic variates variance reduction. Finally, we derive the correlation risk parameters Cora and Gora in our framework so that correlation hedging of quanto options can be performed.展开更多
There’s a popular saying that captures the deep and heartfelt connection between China and Thailand:“China and Thailand are not strangers,but brothers”—or in Chinese,“中泰一家亲.”This phrase is more than just a ...There’s a popular saying that captures the deep and heartfelt connection between China and Thailand:“China and Thailand are not strangers,but brothers”—or in Chinese,“中泰一家亲.”This phrase is more than just a charming proverb.It reflects centuries of migration,shared traditions,and growing goodwill between two nations whose relationship has matured into one of the most enduring and peoplecentered partnerships in Asia.展开更多
When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is...When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is necessary to consider the diversity of control targets and the complexity of dynamic models,which brings the challenge of high-precision tracking control of the stack output power and cathode intake flow.For system idle speed control,a modelbased nonlinear control framework is constructed in this paper.Firstly,the nonlinear dynamic model of output power and cathode intake flow is derived.Secondly,a control scheme combining nonlinear extended Kalman filter observer and state feedback controller is designed.Finally,the control scheme is verified on the PEMFC experimental platform and compared with the proportion-integration-differentiation(PID)controller.The experimental results show that the control strategy proposed in this paper can realize the idle speed control of the fuel cell system and achieve the purpose of zero power output.Compared with PID controller,it has faster response speed and better system dynamics.展开更多
AIM:To evaluate whether fluid-air exchange is an effective treatment for unclosed macular hole(MH)after primary vitrectomy.METHODS:This retrospective study included patients with an unclosed MH within 1–2wk after vit...AIM:To evaluate whether fluid-air exchange is an effective treatment for unclosed macular hole(MH)after primary vitrectomy.METHODS:This retrospective study included patients with an unclosed MH within 1–2wk after vitrectomy.Patients were divided into the vitrectomy,fluid-air exchange,and observation groups according to the secondary treatment.The anatomical outcomes and postoperative visual acuity were recorded.RESULTS:The analysis included 25 eyes in 25 patients(16 females)aged 37–74y(vitrectomy group,n=10;fluid-air exchange group,n=9;observation group,n=6).Closure rate after secondary treatment was 100%in the vitrectomy group,88.9%in the fluid-air exchange group and 33.3%in the observation group.Optical coherence tomography images obtained at the last follow-up revealed that continuity of the external limiting membrane(ELM)was significantly more common(P=0.004)in the fluid-air group(8/9 eyes,88.9%)than in the vitrectomy group(2/10 eyes,20.0%)and that macular morphology was better in the fluid-air group than in the vitrectomy group.No serious complications were observed after secondary treatment.CONCLUSION:Fluid-air exchange is an alternative option to repeat vitrectomy for patients with an unclosed MH after initial vitrectomy with elevated macular edge.展开更多
Polyploidy,or whole-genome duplication,is an important evolutionary process that has shaped the genomes and traits of many plants,including numerous important crops.The Brassica genus,which includes diverse vegetables...Polyploidy,or whole-genome duplication,is an important evolutionary process that has shaped the genomes and traits of many plants,including numerous important crops.The Brassica genus,which includes diverse vegetables and oilseeds,is a key model system for studying how polyploidy affects plant diversification and domestication.This review summarizes the current understanding of how multiple rounds of ancient and more recent polyploidization events laid the foundation for the wide diversity seen in Brassica.We discuss the key outcomes through which polyploidy facilitates the accumulation of genetic variation,including genomic buffering that enables mutation retention.Furthermore,we explore the significant roles of interspecies and interploidy introgression in introducing external genetic novelty.We highlight homoeologous exchange(HE)as a critical mechanism unique to allopolyploids,driving substantial genomic rearrangements including presence-absence variations and gene dosage alterations that directly contribute to significant phenotypic innovation and adaptation in Brassica.Together,these polyploidy-associated processes have led to the extensive range of genomic variations that shaped great morphological diversification in the domestication of Brassica.By integrating insights from genomics,genetics,and evolutionary biology,this review shows how polyploidy has been central to Brassica's success and agricultural value.We also suggest future research areas to better understand polyploid evolution and improve crop breeding.展开更多
This article aims to analyze the repercussions of food trade between China and various regions of the world to understand the dynamics of food flows and offer a novel perspective on the contemporary globalization proc...This article aims to analyze the repercussions of food trade between China and various regions of the world to understand the dynamics of food flows and offer a novel perspective on the contemporary globalization process.Understanding these flows involves analyzing the global production and commercialization of food and the effects of these movements on exporting and importing countries in economic terms and food security.The concept of unequal caloric exchange is applied to the case of China,which allows for an understanding of how its economic growth and participation in international trade have transformed its global and internal commercial dynamics by establishing links with self-sufficiency and the composition of its population’s diet.The results show that China is increasingly dependent on international markets for its food supply.From 1961 to 2021,food consumption in China has tripled in calories and experienced qualitative changes,with a reduction in high-quality carbohydrates and vegetable proteins and an increase in cereals,vegetable oils,alcohol,and vegetables.This dietary transformation is related to economic growth and greater dependence on international trade.From 1987 to 2022,China has shown a growing deficit in the food trade balance,with imports exceeding exports in volume,value,and calories,although it maintains favorable terms of trade.Food self-sufficiency has decreased from 95%in 1961 to 76%in 2022,and the diet has diversified,replacing traditional foods with products demanded in international trade.展开更多
文摘A Tibetan art form bridges the past and present and connects cultures around the world.THANGKA,a unique form of Tibetan sacred painting,is gaining prominence globally due to its vibrant colors,exquisite craftsmanship,and profound religious and cultural significance.With the acceleration of globalization,this symbol of Tibetan culture that combines artistic expression with spirituality has become a bridge for cultural exchange between the East and the West.Recently,China Today spoke to Yixi Puncog,art collector and council member of the China Association for Preservation and Development of Tibetan Culture,to learn more about Thangka art,its role in international exchange,and how it is enhancing China’s cultural soft power.
基金supported by The University of Hong Kong,China(109000487,109001694,204610401,and 204610519)National Natural Science Foundation of China(82402225)(to JH).
文摘Chemical exchange saturation transfer magnetic resonance imaging is an advanced imaging technique that enables the detection of compounds at low concentrations with high sensitivity and spatial resolution and has been extensively studied for diagnosing malignancy and stroke.In recent years,the emerging exploration of chemical exchange saturation transfer magnetic resonance imaging for detecting pathological changes in neurodegenerative diseases has opened up new possibilities for early detection and repetitive scans without ionizing radiation.This review serves as an overview of chemical exchange saturation transfer magnetic resonance imaging with detailed information on contrast mechanisms and processing methods and summarizes recent developments in both clinical and preclinical studies of chemical exchange saturation transfer magnetic resonance imaging for Alzheimer’s disease,Parkinson’s disease,multiple sclerosis,and Huntington’s disease.A comprehensive literature search was conducted using databases such as PubMed and Google Scholar,focusing on peer-reviewed articles from the past 15 years relevant to clinical and preclinical applications.The findings suggest that chemical exchange saturation transfer magnetic resonance imaging has the potential to detect molecular changes and altered metabolism,which may aid in early diagnosis and assessment of the severity of neurodegenerative diseases.Although promising results have been observed in selected clinical and preclinical trials,further validations are needed to evaluate their clinical value.When combined with other imaging modalities and advanced analytical methods,chemical exchange saturation transfer magnetic resonance imaging shows potential as an in vivo biomarker,enhancing the understanding of neuropathological mechanisms in neurodegenerative diseases.
基金National Key R&D Program of China,Grant/Award Number:2021YFA1500900Basic and Applied Basic Research Foundation of Guangdong Province-Regional Joint Fund Project,Grant/Award Number:2021B1515120024+9 种基金Science Funds of the Education Office of Jiangxi Province,Grant/Award Number:GJJ2201324Science Funds of Jiangxi Province,Grant/Award Numbers:20242BAB25168,20224BAB213018Doctoral Research Start-up Funds of JXSTNU,Grant/Award Number:2022BSQD05China Postdoctoral Science Foundation,Grant/Award Number:2023M741121National Natural Science Foundation of China,Grant/Award Number:22172047Provincial Natural Science Foundation of Hunan,Grant/Award Number:2021JJ30089Shenzhen Science and Technology Program,Grant/Award Number:JCYJ20210324122209025Changsha Municipal Natural Science Foundation,Grant/Award Number:kq2107008Hunan Province of Huxiang Talent project,Grant/Award Number:2023rc3118Natural Science Foundation of Hunan Province,Grant/Award Number:2022JJ10006.
文摘Hydrogen energy from electrocatalysis driven by sustainable energy has emerged as a solution against the background of carbon neutrality.Proton exchange membrane(PEM)-based electrocatalytic systems represent a promising technology for hydrogen production,which is equipped to combine efficiently with intermittent electricity from renewable energy sources.In this review,PEM-based electrocatalytic systems for H2 production are summarized systematically from low to high operating temperature systems.When the operating temperature is below 130℃,the representative device is a PEM water electrolyzer;its core components and respective functions,research status,and design strategies of key materials especially in electrocatalysts are presented and discussed.However,strong acidity,highly oxidative operating conditions,and the sluggish kinetics of the anode reaction of PEM water electrolyzers have limited their further development and shifted our attention to higher operating temperature PEM systems.Increasing the temperature of PEM-based electrocatalytic systems can cause an increase in current density,accelerate reaction kinetics and gas transport and reduce the ohmic value,activation losses,ΔGH*,and power consumption.Moreover,further increasing the operating temperature(120-300℃)of PEM-based devices endows various hydrogen carriers(e.g.,methanol,ethanol,and ammonia)with electrolysis,offering a new opportunity to produce hydrogen using PEM-based electrocatalytic systems.Finally,several future directions and prospects for developing PEM-based electrocatalytic systems for H_(2) production are proposed through devoting more efforts to the key components of devices and reduction of costs.
基金“Grassland Talents”of Inner Mongolia Autonomous Region,Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(NJYT23030)Technology Breakthrough Engineering Hydrogen Energy Field“Unveiling and Leading”Project(2024KJTW0018)+3 种基金“Steed Plan High Level Talents”of Inner Mongolia University,Carbon neutralization research project(STZX202218)National Natural Science Foundation of China(U22A20107),Inner Mongolia Autonomous Region Natural Science Foundation(2023MS02002)Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion(MATEC2024KF011)National Key R&D Program of China(2022YFA1205201).
文摘Anion exchange membrane(AEM),as a kind of key membrane materials,has shown great application potential in many electrochemical fields,and remarkable progress has been made in related research in recent years.In this paper,the research status of AEM is reviewed,including its material design,preparation method,performance optimization and application in the fields of hydrogen production by electrolytic water,fuel cell and water treatment.In terms of material design,new polymer skeleton structures are emerging to regulate the stability of ion conduction channels and membranes by introducing specific functional groups or changing the molecular chain structure.The preparation methods have been gradually expanded from the traditional solution casting method to more advanced technologies,such as interfacial polymerization and electrostatic spinning,which effectively improve the microstructure and property uniformity of the film.Performance optimization focuses on improving ion conductivity,reducing membrane swelling rate and enhancing chemical stability,and a variety of modification strategies are developed and applied.Despite the achievements made so far,there are still some challenges,such as the lack of long-term stability in highly alkaline environments.Future research needs to further explore new material systems and preparation processes in order to promote the wide application and sustainable development of AEM technology in energy,environmental protection and other fields.
文摘Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s constant. The solution to Dirac equation gives four, real, 2-vectors solutions ψ1=(U1D1)ψ2=(U2D2)ψ3=(U3D3)ψ4=(U4D4)where (ψ1,ψ4) are coupled via linear combinations to yield spin-up and spin-down fermions. Likewise, (ψ2,ψ3) are coupled via linear combinations to represent spin-up and spin-down anti-fermions. Here, a deeper investigation of the free fermion internal frequency is discussed, hinting to an exchange interaction between the two components of which a fermion is made of. An upper limit estimate is given to the strength of this interaction.
文摘The Fourth Dialogue on Exchanges and Mutual Learning Among Civilisations was held in Dunhuang in Northwest China's Gansu Province on Friday,bringing together politicians,heads of international organisations,scholars and experts to discuss the significance of exchanges and dialogues between different civilisations in a world facing many conflicts.
文摘In his speech,Han Zheng said that exchanges and mutual learning among civilisations are important driving forces for the advancement of human civilisation as well as world peace and development.President Xi Jinping pointed out that civilisations become richer and more colourful with exchanges and mutual learning.As the futures of all countries are closely interconnected,inclusiveness,coexistence,exchanges and mutual learning among different civilisations will contribute to the common progress of humanity and promote global prosperity and development.
文摘This study develops an analytical model to evaluate the cooling performance of a porous terracotta tubular direct evaporative heat and mass exchanger. By combining energy and mass balance equations with heat and mass transfer coefficients and air psychrometric correlations, the model provides insights into the impact of design and operational parameters on the exchanger cooling performance. Validated against an established numerical model, it accurately simulates cooling behavior with a Root Mean Square Deviation of 0.43 - 1.18˚C under varying inlet air conditions. The results show that tube geometry, including equivalent diameter, flatness ratio, and length significantly influences cooling outcomes. Smaller diameters enhance wet-bulb effectiveness but reduce cooling capacity, while increased flatness and length improve both. For example, extending the flatness ratio of a 15 mm diameter, 0.6 m long tube from 1 (circular) to 4 raises the exchange surface area from 0.028 to 0.037 m2, increasing wet-bulb effectiveness from 60% to 71%. Recommended diameters range from 5 mm for tubes under 0.5 m to 1 cm for tubes 0.5 to 1 m in length. Optimal air velocities depend on tube length: 1 m/s for tubes under 0.8 m, 1.5 m/s for lengths of 0.8 to 1.2 m, and up to 2 m/s for longer tubes. This model offers a practical alternative to complex numerical and CFD methods, with potential applications in cooling tower optimization for thermal and nuclear power plants and geothermal heat exchangers.
文摘China and Indonesia enjoy a long history of cultural and people-to-people exchanges.China’s porcelain and silk and Indonesia’s spices and wood were traded along the Maritime Silk Road since the Han Dynasty(202 BC-AD 220).During the Ming Dynasty(1368-1644),legendary Chinese explorer Zheng He brought Chinese silk,porcelain,and culture to Indonesia during his seven epic voyages.Historical sites and memories about Zheng He have been preserved in many places of Indonesia to this day.
基金UKRI financial support under grant number EP/Y026098/1 for Global Hydrogen Production Technologies(HyPT)Center。
文摘Anion-exchange membrane water electrolysers(AEMWEs)and fuel cells(AEMFCs)are critical technologies for converting renewable resources into green hydrogen(H_(2)),where anion-exchange membranes(AEMs)play a vital role in efficiently transporting hydroxide ions(OH^(-))and minimizing fuel crossover,thus enhancing overall efficiency.While conventional AEMs with linear,side-chain,and block polymer architectures show promise through functionalization,their long-term performance remains a concern.To address this,hyperbranched polymers offer a promising alternative due to their three-dimensional structure,higher terminal functionality,and ease of functionalization.This unique architecture provides interconnected ion transport pathways,fractional free volume,and enhanced long-term stability in alkaline environments.Recent studies have achieved conductivities as high as 304.5 mS cm^(-1),attributed to their improved fractional free volume and microphase separation in hyperbranched AEMs.This review explores the chemical,mechanical,and ionic properties of hyperbranched AEMs in AEMFCs and assesses their potential for application in AEMWEs.Strategies such as blending and structural functionalisation have significantly improved the properties by promoting microphase separation and increasing the density of cationic groups on the polymer surface.The review provides essential insights for future research,highlighting the challenges and opportunities in developing high-performance hyperbranched AEMs to advance hydrogen energy infrastructure.
文摘Cambodia and China have long enjoyed a close relationship grounded in centuries of historical,cultural,and political ties.From their early connections in the 13th Century to today’s multifaceted partnership,the bond between these two nations has been built on mutual respect and cooperation,fortified by economic collaboration and a profound connection between their peoples.Since the formal establishment of diplomatic ties in 1958,Cambodia and China have fostered an enduring“ironclad”friendship that weathered challenges and adapted to the everchanging global dynamics.
文摘The China-CEEC Standardization Exchange Event on Science, Technology and Innovation was convened on December 12-13, 2024 in Yiwu, Zhejiang province.Hosted by China Science and Technology Exchange Center and held by China Jiliang University (CJLU), the event was themed “standards innovation promotes high-quality development:tasks and challenges of standardization development of biomanufacturing”, which is the third event of the series of activities, China-CEEC Inno Share, in 2024.More than 150 representatives from governments, universities, research institutions and enterprises in 15 countries attended the meeting to discuss cutting-edge achievements in sci-tech innovation.
文摘On March 5,the 2025 Cultural Exchange Activity for the Spouses of Diplomats in China themed“A Women’s Gathering.Stitching a Beautiful World”was held at EVE Castle in Beijing.This event was co-organized by the Spouses of Diplomats’Club and the Mexican Embassy in China.The wives of Ambassadors from many countries around the world have gathered in Beijing to celebrate International Women’s Day.
基金support by the Shanghai Engineering Research Center for Shallow Geothermal Energy(DRZX-202306)Shaanxi Coal Geology Group Co.,Ltd.(SMDZ-ZD2024-23)+4 种基金Key Laboratory of Coal Resources Exploration and Comprehensive Utilization,Ministry of Natural Resources,China(ZP2020-1)Shaanxi Investment Group Co.,Ltd.(SIGC2023-KY-05)Key Research and Development Projects of Shaanxi Province(2023-GHZD-54)Shaanxi Qinchuangyuan Scientist+Engineer Team Construction Project(2022KXJ-049)China Postdoctoral Science Foundation(2023M742802,2024T170721).
文摘Geothermal energy,a form of renewable energy,has been extensively utilized for building heating.However,there is a lack of detailed comparative studies on the use of shallow and medium-deep geothermal energy in building energy systems,which are essential for decision-making.Therefore,this paper presents a comparative study of the performance and economic analysis of shallow and medium-deep borehole heat exchanger heating systems.Based on the geological parameters of Xi’an,China and commonly used borehole heat exchanger structures,numerical simulationmethods are employed to analyze performance and economic efficiency.The results indicate that increasing the spacing between shallow borehole heat exchangers can effectively reduce thermal interference between the pipes and improve heat extraction performance.As the flow rate increases,the outlet water temperature ranges from 279.3 to 279.7 K,with heat extraction power varying between 595 and 609 W.For medium-deep borehole heat exchangers,performance predictions show that a higher flow rate results in greater heat extraction power.However,when the flow rate exceeds 30 m^(3)/h,further increases in flow rate have only a minor effect on enhancing heat extraction power.Additionally,the economic analysis reveals that the payback period for shallow geothermal heating systems ranges from 10 to 11 years,while for medium-deep geothermal heating systems,it varies more widely from 3 to 25 years.Therefore,the payback period for medium-deep geothermal heating systems is more significantly influenced by operational and installation parameters,and optimizing these parameters can considerably shorten the payback period.The results of this study are expected to provide valuable insights into the efficient and cost-effective utilization of geothermal energy for building heating.
文摘Quanto options allow the buyer to exchange the foreign currency payoff into the domestic currency at a fixed exchange rate. We investigate quanto options with multiple underlying assets valued in different foreign currencies each with a different strike price in the payoff function. We carry out a comparative performance analysis of different stochastic volatility (SV), stochastic correlation (SC), and stochastic exchange rate (SER) models to determine the best combination of these models for Monte Carlo (MC) simulation pricing. In addition, we test the performance of all model variants with constant correlation as a benchmark. We find that a combination of GARCH-Jump SV, Weibull SC, and Ornstein Uhlenbeck (OU) SER performs best. In addition, we analyze different discretization schemes and their results. In our simulations, the Milstein scheme yields the best balance between execution times and lower standard deviations of price estimates. Furthermore, we find that incorporating mean reversion into stochastic correlation and stochastic FX rate modeling is beneficial for MC simulation pricing. We improve the accuracy of our simulations by implementing antithetic variates variance reduction. Finally, we derive the correlation risk parameters Cora and Gora in our framework so that correlation hedging of quanto options can be performed.
文摘There’s a popular saying that captures the deep and heartfelt connection between China and Thailand:“China and Thailand are not strangers,but brothers”—or in Chinese,“中泰一家亲.”This phrase is more than just a charming proverb.It reflects centuries of migration,shared traditions,and growing goodwill between two nations whose relationship has matured into one of the most enduring and peoplecentered partnerships in Asia.
基金Supported by the Major Science and Technology Projects in Jilin Province and Changchun City(20220301010GX).
文摘When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is necessary to consider the diversity of control targets and the complexity of dynamic models,which brings the challenge of high-precision tracking control of the stack output power and cathode intake flow.For system idle speed control,a modelbased nonlinear control framework is constructed in this paper.Firstly,the nonlinear dynamic model of output power and cathode intake flow is derived.Secondly,a control scheme combining nonlinear extended Kalman filter observer and state feedback controller is designed.Finally,the control scheme is verified on the PEMFC experimental platform and compared with the proportion-integration-differentiation(PID)controller.The experimental results show that the control strategy proposed in this paper can realize the idle speed control of the fuel cell system and achieve the purpose of zero power output.Compared with PID controller,it has faster response speed and better system dynamics.
文摘AIM:To evaluate whether fluid-air exchange is an effective treatment for unclosed macular hole(MH)after primary vitrectomy.METHODS:This retrospective study included patients with an unclosed MH within 1–2wk after vitrectomy.Patients were divided into the vitrectomy,fluid-air exchange,and observation groups according to the secondary treatment.The anatomical outcomes and postoperative visual acuity were recorded.RESULTS:The analysis included 25 eyes in 25 patients(16 females)aged 37–74y(vitrectomy group,n=10;fluid-air exchange group,n=9;observation group,n=6).Closure rate after secondary treatment was 100%in the vitrectomy group,88.9%in the fluid-air exchange group and 33.3%in the observation group.Optical coherence tomography images obtained at the last follow-up revealed that continuity of the external limiting membrane(ELM)was significantly more common(P=0.004)in the fluid-air group(8/9 eyes,88.9%)than in the vitrectomy group(2/10 eyes,20.0%)and that macular morphology was better in the fluid-air group than in the vitrectomy group.No serious complications were observed after secondary treatment.CONCLUSION:Fluid-air exchange is an alternative option to repeat vitrectomy for patients with an unclosed MH after initial vitrectomy with elevated macular edge.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFF1000104)the Agricultural Science and Technology Innovation Program(ASTIP),Beijing Municipal Science and Technology Project(Grant No.Z231100003723009)+4 种基金the Central Public-interest Scientific Institution Basal Research Fund(Grant No.Y2023PT16)TKI project(Grant No.KV1605-004)support from the China Scholarship Councilthe NPO bursary funding from Wageningen universitythe scholarship from Institute of vegetables and flowers,CAAS.
文摘Polyploidy,or whole-genome duplication,is an important evolutionary process that has shaped the genomes and traits of many plants,including numerous important crops.The Brassica genus,which includes diverse vegetables and oilseeds,is a key model system for studying how polyploidy affects plant diversification and domestication.This review summarizes the current understanding of how multiple rounds of ancient and more recent polyploidization events laid the foundation for the wide diversity seen in Brassica.We discuss the key outcomes through which polyploidy facilitates the accumulation of genetic variation,including genomic buffering that enables mutation retention.Furthermore,we explore the significant roles of interspecies and interploidy introgression in introducing external genetic novelty.We highlight homoeologous exchange(HE)as a critical mechanism unique to allopolyploids,driving substantial genomic rearrangements including presence-absence variations and gene dosage alterations that directly contribute to significant phenotypic innovation and adaptation in Brassica.Together,these polyploidy-associated processes have led to the extensive range of genomic variations that shaped great morphological diversification in the domestication of Brassica.By integrating insights from genomics,genetics,and evolutionary biology,this review shows how polyploidy has been central to Brassica's success and agricultural value.We also suggest future research areas to better understand polyploid evolution and improve crop breeding.
基金supported by the Government of Catalonia,and the ETOS project(TED2021-132032A-I00)supported by the Spanish Ministry of Science and Innovation.
文摘This article aims to analyze the repercussions of food trade between China and various regions of the world to understand the dynamics of food flows and offer a novel perspective on the contemporary globalization process.Understanding these flows involves analyzing the global production and commercialization of food and the effects of these movements on exporting and importing countries in economic terms and food security.The concept of unequal caloric exchange is applied to the case of China,which allows for an understanding of how its economic growth and participation in international trade have transformed its global and internal commercial dynamics by establishing links with self-sufficiency and the composition of its population’s diet.The results show that China is increasingly dependent on international markets for its food supply.From 1961 to 2021,food consumption in China has tripled in calories and experienced qualitative changes,with a reduction in high-quality carbohydrates and vegetable proteins and an increase in cereals,vegetable oils,alcohol,and vegetables.This dietary transformation is related to economic growth and greater dependence on international trade.From 1987 to 2022,China has shown a growing deficit in the food trade balance,with imports exceeding exports in volume,value,and calories,although it maintains favorable terms of trade.Food self-sufficiency has decreased from 95%in 1961 to 76%in 2022,and the diet has diversified,replacing traditional foods with products demanded in international trade.
