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
Coiled tube heat exchangers are widely preferred in shell structures due to their superior heat transfer performance,driven by favorable flow characteristics.This study investigates the effect of modifying coil and sh...Coiled tube heat exchangers are widely preferred in shell structures due to their superior heat transfer performance,driven by favorable flow characteristics.This study investigates the effect of modifying coil and shell configurations on heat transfer efficiency.Two key enhancements were examined:adding fins to the outer coil surface and integrating longitudinal slots within a hollowed shell.These modifications promote turbulence and extend heat transfer duration,thereby improving performance.However,they also introduce challenges,including increased pressure loss andmanufacturing complexity.Numerical simulationswere conducted usingANSYS Fluent 2024R1 under identical boundary conditions.With a fixed cold-side flow rate of 3 L/min,the input temperatures for the hot and cold fluids were 333.15 and 291.65 K,respectively.The hot-side flow rate varied between 2 and 6 L/min.Simulation outcomes were reported for the objectives of the study that included the improvement in heat exchangers’heat transfer enhancement.As it was indicated in the study outcomes,the average heat transfer rate increased by 15.56%,the overall heat transfer coefficient enhanced by about 29.51%,and the convective heat transfer coefficient improved by about 75.96%compared to the conventional shell-and-coil tube heat exchanger model.However,the modified technique resulted in a significant pressure drop.展开更多
ISO releases two standards for textiles.Recently,two international standards,ISO 8159:2025,Textiles-Morphology of fibres and yarns-Vocabulary,and ISO 17971:2025,Textiles-Smart textiles-Test method for determining the ...ISO releases two standards for textiles.Recently,two international standards,ISO 8159:2025,Textiles-Morphology of fibres and yarns-Vocabulary,and ISO 17971:2025,Textiles-Smart textiles-Test method for determining the screen-touch properties of fabrics,were officially released.They are of positive significance for eliminating technical ambiguities in exchanges on textile products and filling the gaps in international standards.展开更多
The increased interest in geothermal energy is evident,along with the exploitation of traditional hydrothermal systems,in the growing research and projects developing around the reuse of already-drilled oil,gas,and ex...The increased interest in geothermal energy is evident,along with the exploitation of traditional hydrothermal systems,in the growing research and projects developing around the reuse of already-drilled oil,gas,and exploration wells.The Republic of Croatia has around 4000 wells,however,due to a long period since most of these wells were drilled and completed,there is uncertainty about how many are available for retrofitting as deep-borehole heat exchangers.Nevertheless,as hydrocarbon production decreases,it is expected that the number of wells available for the revitalization and exploitation of geothermal energy will increase.The revitalization of wells via deep-borehole heat exchangers involves installing a coaxial heat exchanger and circulating the working fluid in a closed system,during which heat is transferred from the surrounding rock medium to the circulating fluid.Since drilled wells are not of uniformdepth and are located in areas with different thermal rock properties and geothermal gradients,an analysis was conducted to determine available thermal energy as a function of well depth,geothermal gradient,and circulating fluid flow rate.Additionally,an economic analysis was performed to determine the benefits of retrofitting existing assets,such as drilled wells,compared to drilling new wells to obtain the same amount of thermal energy.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
Indian Railways have been the largest people moving transport infrastructure in India.Over the years the systems and trains have been upgraded resulting in both better passenger amenities and reduction in travel time....Indian Railways have been the largest people moving transport infrastructure in India.Over the years the systems and trains have been upgraded resulting in both better passenger amenities and reduction in travel time.The newest addition is the Vande Bharat Express,a semi-high-speed train that was introduced in India in 2019.The train currently runs between 10 routes and has brought significant changes to India’s railway network.This article explores the introduction of Vande Bharat Express trains in India and its effects on the country’s interstation time-space shrinkage using cartographic techniques.The cartographic techniques like stepwise multidimensional scaling and interpolation using the distance cartogram plugin in QGIS are mainly used for generating the time-space maps for various speeds.The limitations of these techniques and the methods to overcome those limitations are also explored in this article.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 paper is devoted to investigating the spreading speed of a time-space periodic epidemic model with vital dynamics and standard incidence in discrete media. We establish the existence of the leftward and rightward...This paper is devoted to investigating the spreading speed of a time-space periodic epidemic model with vital dynamics and standard incidence in discrete media. We establish the existence of the leftward and rightward spreading speeds for the infective individuals, which can be used to estimate how fast the disease spreads. To overcome the difficulty arising from the lack of comparison principle for such time-space periodic nonmonotone systems, our proof is mainly based on constructing a series of scalar time-space periodic equations, establishing the spreading speeds for such auxiliary equations and using comparison methods. It may be the first work to study the spreading speed for time-space periodic non-monotone systems.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
Seismic anisotropy has been extensively acknowledged as a crucial element that influences the wave propagation characteristic during wavefield simulation,inversion and imaging.Transversely isotropy(TI)and orthorhombic...Seismic anisotropy has been extensively acknowledged as a crucial element that influences the wave propagation characteristic during wavefield simulation,inversion and imaging.Transversely isotropy(TI)and orthorhombic anisotropy(OA)are two typical categories of anisotropic media in exploration geophysics.In comparison of the elastic wave equations in both TI and OA media,pseudo-acoustic wave equations(PWEs)based on the acoustic assumption can markedly reduce computational cost and complexity.However,the presently available PWEs may experience SV-wave contamination and instability when anisotropic parameters cannot satisfy the approximated condition.Exploiting pure-mode wave equations can effectively resolve the above-mentioned issues and generate pure P-wave events without any artifacts.To further improve the computational accuracy and efficiency,we develop two novel pure qP-wave equations(PPEs)and illustrate the corresponding numerical solutions in the timespace domain for 3D tilted TI(TTI)and tilted OA(TOA)media.First,the rational polynomials are adopted to estimate the exact pure qP-wave dispersion relations,which contain complicated pseudo-differential operators with irrational forms.The polynomial coefficients are produced by applying a linear optimization algorithm to minimize the objective function difference between the expansion formula and the exact one.Then,the developed optimized PPEs are efficiently implemented using the finite-difference(FD)method in the time-space domain by introducing a scalar operator,which can help avoid the problem of spectral-based algorithms and other calculation burdens.Structures of the new equations are concise and corresponding implementation processes are straightforward.Phase velocity analyses indicate that our proposed optimized equations can lead to reliable approximation results.3D synthetic examples demonstrate that our proposed FD-based PPEs can produce accurate and stable P-wave responses,and effectively describe the wavefield features in complicated TTI and TOA media.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
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.
文摘Coiled tube heat exchangers are widely preferred in shell structures due to their superior heat transfer performance,driven by favorable flow characteristics.This study investigates the effect of modifying coil and shell configurations on heat transfer efficiency.Two key enhancements were examined:adding fins to the outer coil surface and integrating longitudinal slots within a hollowed shell.These modifications promote turbulence and extend heat transfer duration,thereby improving performance.However,they also introduce challenges,including increased pressure loss andmanufacturing complexity.Numerical simulationswere conducted usingANSYS Fluent 2024R1 under identical boundary conditions.With a fixed cold-side flow rate of 3 L/min,the input temperatures for the hot and cold fluids were 333.15 and 291.65 K,respectively.The hot-side flow rate varied between 2 and 6 L/min.Simulation outcomes were reported for the objectives of the study that included the improvement in heat exchangers’heat transfer enhancement.As it was indicated in the study outcomes,the average heat transfer rate increased by 15.56%,the overall heat transfer coefficient enhanced by about 29.51%,and the convective heat transfer coefficient improved by about 75.96%compared to the conventional shell-and-coil tube heat exchanger model.However,the modified technique resulted in a significant pressure drop.
文摘ISO releases two standards for textiles.Recently,two international standards,ISO 8159:2025,Textiles-Morphology of fibres and yarns-Vocabulary,and ISO 17971:2025,Textiles-Smart textiles-Test method for determining the screen-touch properties of fabrics,were officially released.They are of positive significance for eliminating technical ambiguities in exchanges on textile products and filling the gaps in international standards.
文摘The increased interest in geothermal energy is evident,along with the exploitation of traditional hydrothermal systems,in the growing research and projects developing around the reuse of already-drilled oil,gas,and exploration wells.The Republic of Croatia has around 4000 wells,however,due to a long period since most of these wells were drilled and completed,there is uncertainty about how many are available for retrofitting as deep-borehole heat exchangers.Nevertheless,as hydrocarbon production decreases,it is expected that the number of wells available for the revitalization and exploitation of geothermal energy will increase.The revitalization of wells via deep-borehole heat exchangers involves installing a coaxial heat exchanger and circulating the working fluid in a closed system,during which heat is transferred from the surrounding rock medium to the circulating fluid.Since drilled wells are not of uniformdepth and are located in areas with different thermal rock properties and geothermal gradients,an analysis was conducted to determine available thermal energy as a function of well depth,geothermal gradient,and circulating fluid flow rate.Additionally,an economic analysis was performed to determine the benefits of retrofitting existing assets,such as drilled wells,compared to drilling new wells to obtain the same amount of thermal energy.
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Indian Railways have been the largest people moving transport infrastructure in India.Over the years the systems and trains have been upgraded resulting in both better passenger amenities and reduction in travel time.The newest addition is the Vande Bharat Express,a semi-high-speed train that was introduced in India in 2019.The train currently runs between 10 routes and has brought significant changes to India’s railway network.This article explores the introduction of Vande Bharat Express trains in India and its effects on the country’s interstation time-space shrinkage using cartographic techniques.The cartographic techniques like stepwise multidimensional scaling and interpolation using the distance cartogram plugin in QGIS are mainly used for generating the time-space maps for various speeds.The limitations of these techniques and the methods to overcome those limitations are also explored in this article.
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.
基金supported by the Natural Science Basic Research Program of Shanxi(Grant No.2024JC-YBMS-025)the Innovation Capability Support Program of Shanxi(Grant No.2024RS-CXTD-88)。
文摘This paper is devoted to investigating the spreading speed of a time-space periodic epidemic model with vital dynamics and standard incidence in discrete media. We establish the existence of the leftward and rightward spreading speeds for the infective individuals, which can be used to estimate how fast the disease spreads. To overcome the difficulty arising from the lack of comparison principle for such time-space periodic nonmonotone systems, our proof is mainly based on constructing a series of scalar time-space periodic equations, establishing the spreading speeds for such auxiliary equations and using comparison methods. It may be the first work to study the spreading speed for time-space periodic non-monotone systems.
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.
基金supported by the National Key R&D Program of China(2021YFA0716902)National Natural Science Foundation of China(NSFC)under contract number 42374149 and 42004119National Science and Technology Major Project(2024ZD1002907)。
文摘Seismic anisotropy has been extensively acknowledged as a crucial element that influences the wave propagation characteristic during wavefield simulation,inversion and imaging.Transversely isotropy(TI)and orthorhombic anisotropy(OA)are two typical categories of anisotropic media in exploration geophysics.In comparison of the elastic wave equations in both TI and OA media,pseudo-acoustic wave equations(PWEs)based on the acoustic assumption can markedly reduce computational cost and complexity.However,the presently available PWEs may experience SV-wave contamination and instability when anisotropic parameters cannot satisfy the approximated condition.Exploiting pure-mode wave equations can effectively resolve the above-mentioned issues and generate pure P-wave events without any artifacts.To further improve the computational accuracy and efficiency,we develop two novel pure qP-wave equations(PPEs)and illustrate the corresponding numerical solutions in the timespace domain for 3D tilted TI(TTI)and tilted OA(TOA)media.First,the rational polynomials are adopted to estimate the exact pure qP-wave dispersion relations,which contain complicated pseudo-differential operators with irrational forms.The polynomial coefficients are produced by applying a linear optimization algorithm to minimize the objective function difference between the expansion formula and the exact one.Then,the developed optimized PPEs are efficiently implemented using the finite-difference(FD)method in the time-space domain by introducing a scalar operator,which can help avoid the problem of spectral-based algorithms and other calculation burdens.Structures of the new equations are concise and corresponding implementation processes are straightforward.Phase velocity analyses indicate that our proposed optimized equations can lead to reliable approximation results.3D synthetic examples demonstrate that our proposed FD-based PPEs can produce accurate and stable P-wave responses,and effectively describe the wavefield features in complicated TTI and TOA media.
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.
