Metasurfaces,ultrathin metamaterials constructed by planar meta-atoms with tailored electromagnetic(EM)responses,have attracted tremendous attention due to their exotic abilities to freely control EM waves.With active...Metasurfaces,ultrathin metamaterials constructed by planar meta-atoms with tailored electromagnetic(EM)responses,have attracted tremendous attention due to their exotic abilities to freely control EM waves.With active elements incorporated into metasurface designs,one can realize tunable and/or reconfgurable metadevices with functionalities controlled by external stimuli,opening a new platform to dynamically manipulate EM waves.In this article,we briefy review recent progress on tunable/reconfgurable metasurfaces,focusing on their working mechanisms and practical applications.We frst describe available approaches,categorized into diferent classes based on external stimuli applied,to realize homogeneous tunable/reconfgurable metasurfaces,which can ofer uniform manipulations on EM waves.We next summarize recent achievements on inhomogeneous tunable/reconfgurable metasurfaces with constitutional meta-atoms locally tuned by external knobs,which can dynamically control the wave-fronts of EM waves.We conclude this review by presenting our own perspectives on possible future directions and existing challenges in this fast developing feld.展开更多
The reactive force-field(ReaxFF)interatomic potential is a powerful computational tool for exploring,developing and optimizing material properties.Methods based on the principles of quantum mechanics(QM),while offerin...The reactive force-field(ReaxFF)interatomic potential is a powerful computational tool for exploring,developing and optimizing material properties.Methods based on the principles of quantum mechanics(QM),while offering valuable theoretical guidance at the electronic level,are often too computationally intense for simulations that consider the full dynamic evolution of a system.Alternatively,empirical interatomic potentials that are based on classical principles require significantly fewer computational resources,which enables simulations to better describe dynamic processes over longer timeframes and on larger scales.Such methods,however,typically require a predefined connectivity between atoms,precluding simulations that involve reactive events.The ReaxFF method was developed to help bridge this gap.Approaching the gap from the classical side,ReaxFF casts the empirical interatomic potential within a bond-order formalism,thus implicitly describing chemical bonding without expensive QM calculations.This article provides an overview of the development,application,and future directions of the ReaxFF method.展开更多
Hepatocellular carcinoma(HCC) is the most common type of primary liver cancer, which in turns accounts for the sixth most common cancer worldwide.Despite being the 6 th most common cancer it is the second leading caus...Hepatocellular carcinoma(HCC) is the most common type of primary liver cancer, which in turns accounts for the sixth most common cancer worldwide.Despite being the 6 th most common cancer it is the second leading cause of cancer related deaths. HCC typically arises in the background of cirrhosis, however,about 20% of cases can develop in a non-cirrhotic liver. This particular subgroup of HCC generally presents at an advanced stage as surveillance is not performed in a non-cirrhotic liver. HCC in non-cirrhotic patients is clinically silent in its early stages because of lack of symptoms and surveillance imaging; and higher hepatic reserve in this population. Interestingly, F3 fibrosis in non-alcoholic fatty liver disease, hepatitis B virus and hepatitis C virus infections are associated with high risk of developing HCC. Even though considerable progress has been made in the management of this entity, there is a dire need for implementation of surveillance strategies in the patient population at risk, to decrease the disease burden at presentation and improve the prognosis of these patients. This comprehensive review details the epidemiology, risk factors, clinical features,diagnosis and management of HCC in non-cirrhotic patients and provides future directions for research.展开更多
One of the main challenges in materials discovery is efficiently exploring the vast search space for targeted properties as approaches that rely on trial-and-error are impractical.We review how methods from the inform...One of the main challenges in materials discovery is efficiently exploring the vast search space for targeted properties as approaches that rely on trial-and-error are impractical.We review how methods from the information sciences enable us to accelerate the search and discovery of new materials.In particular,active learning allows us to effectively navigate the search space iteratively to identify promising candidates for guiding experiments and computations.The approach relies on the use of uncertainties and making predictions from a surrogate model together with a utility function that prioritizes the decision making process on unexplored data.We discuss several utility functions and demonstrate their use in materials science applications,impacting both experimental and computational research.We summarize by indicating generalizations to multiple properties and multifidelity data,and identify challenges,future directions and opportunities in the emerging field of materials informatics.展开更多
Pulsed discharge plasma and its application is one of the promising directions in civilian areas of pulsed power technology.In order to promote the research and development of the theory and application technology for...Pulsed discharge plasma and its application is one of the promising directions in civilian areas of pulsed power technology.In order to promote the research and development of the theory and application technology for pulsed discharge plasma,in this paper,recent progress on the mechanism of nanosecond-pulse gas discharge and the characteristics and applications of typical pulsed plasma at the Institute of Electrical Engineering,Chinese Academy of Sciences is reviewed.Firstly,progress on mechanism of nanosecond-pulse discharge based on runaway electrons and measurement technology of runaway electrons is introduced.Then,the characteristics of three typical discharges,including direct-driven pulsed discharge,pulsed dielectric barrier discharge and pulsed plasma jet,are reviewed.Furthermore,typical plasma applications of pulsed plasma on surface modification and methane conversion are presented.展开更多
To date,the coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has determined 399,600,607 cases and 5,757,562 deaths worldwide.COVID-19 is a serious threat to human ...To date,the coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has determined 399,600,607 cases and 5,757,562 deaths worldwide.COVID-19 is a serious threat to human health globally.The World Health Organization(WHO)has declared COVID-19 pandemic a major public health emergency.Vaccination is the most effective and economical intervention for controlling the spread of epidemics,and consequently saving lives and protecting the health of the population.Various techniques have been employed in the development of COVID-19 vaccines.Among these,the COVID-19 messenger RNA(mRNA)vaccine has been drawing increasing attention owing to its great application prospects and advantages,which include short development cycle,easy industrialization,simple production process,flexibility to respond to new variants,and the capacity to induce better immune response.This review summarizes current knowledge on the structural characteristics,antigen design strategies,delivery systems,industrialization potential,quality control,latest clinical trials and real-world data of COVID-19 mRNA vaccines as well as mRNA technology.Current challenges and future directions in the development of preventive mRNA vaccines for major infectious diseases are also discussed.展开更多
The in-plane dynamic crushing behavior of re-entrant honeycomb is analyzed and compared with the conventional hexagon topology.Detailed deformation modes along two orthogonal directions are examined,where a parametric...The in-plane dynamic crushing behavior of re-entrant honeycomb is analyzed and compared with the conventional hexagon topology.Detailed deformation modes along two orthogonal directions are examined,where a parametric study of the effect of impact velocity and cell wall aspect ratio is performed.An analytical formula of the dynamic crushing strength is then deduced based on the periodic collapse mechanism of cell structures.Comparisons with the finite element results validate the effectiveness of the proposed analytical method.Numerical results also reveal higher plateau stress of re-entrant honeycomb over conventional hexagon topology,implying better energy absorption properties.The underlying physical understanding of the results is emphasized,where the auxetic effect（negative Poisson＇s ratio） induced in the re-entrant topology is believed to be responsible for this superior impact resistance.展开更多
Regional inequality is a core issue in geography,and it can be measured by several approaches and indexes.However,the global inequality measures can not reflect regional characteristics in terms of spatiality and non-...Regional inequality is a core issue in geography,and it can be measured by several approaches and indexes.However,the global inequality measures can not reflect regional characteristics in terms of spatiality and non-mobility,as well as correctly explore regional inequality in particular directions.Although conventional between-group inequality indexes can measure the inequality in particular directions,they can not reflect the reversals of regional patterns and changes of within-group patterns.Therefore,we set forth a new approach to measure regional inequality in particular directions,which is applicable to geographic field.Based on grouping,we established a new index to measure regional inequality in particular directions named Particular Direction Inequality index(PDI index),which is comprised of between-group inequality of all data and between-group average gap.It can reflect regional spatiality and non-mobility,judge the main direction of regional inequality,and capture the changes and reversals of regional patterns.We used the PDI index to measure the changes of regional inequality from 1952 to 2009 in China.The results show that:1) the main direction of China's regional inequality was between coastal areas and inland areas;the increasing extent of inequality between coastal areas and inland areas was higher than the global inequality;2) the PDI index can measure the between-region average gap,and is more sensitive to evolution of within-region patterns;3) the inequality between the northern China and the southern China has been decreasing from 1952 to 2009 and was reversed in 1994 and 1995.展开更多
Flavonoids play essential roles in human health.Apple(Malus domestica Borkh.),one of the most widely produced and economically important fruit crops in temperate regions,is a significant source of flavonoids in the hu...Flavonoids play essential roles in human health.Apple(Malus domestica Borkh.),one of the most widely produced and economically important fruit crops in temperate regions,is a significant source of flavonoids in the human diet and is among the top nutritionally rated and most widely consumed fruits worldwide.Epidemiological studies have shown that the consumption of apples,which are rich in a variety of free and easily absorbable flavonoids,is associated with a decreased risk of various diseases.However,apple production is challenged by serious inbreeding problems.The narrowing of the hereditary base has resulted in apples with poor nutritional quality and low flavonoid contents.Recently,there have been advances in our understanding of the roles that Malus sieversii(Ledeb.)M.Roem has played in the process of apple domestication and breeding.In this study,we review the origin of cultivated apples and red-fleshed apples,and discuss the genetic diversity and construction of the core collections of M.sieversii.We also discuss current research progress and breeding programs on red-skinned and red-fleshed apples and summarize the exploitation and utilization of M.sieversii in the breeding of high-flavonoid,and red-fleshed apples.This study highlights a valuable pattern of horticultural crop breeding using wild germplasm resources.The future challenges and directions of research on the molecular mechanisms of flavonoid accumulation and high-flavonoid apple breeding are discussed.展开更多
The article explores the issue of designing a new design of a loading cylinder with a casing filled with vulcanized rubber for pneumomechanical spinning machines. The theoretical calculation of the deformed state of a...The article explores the issue of designing a new design of a loading cylinder with a casing filled with vulcanized rubber for pneumomechanical spinning machines. The theoretical calculation of the deformed state of a cylindrical shell filled with vulcanized rubber is given. Deflections and stresses in the rubber layer are determined, which we use approximately for the Ritz methods. The theory of the radial and axial moving rubber layer was analyzed. The specific energy of deformation of a cylindrical layer of a compound cylinder is determined. The statics of the case and the loading cylinder of spinning machines are thoroughly studied.展开更多
Oral squamous cell carcinoma (OSCC) develops on the mucosal epithelium of the oral cavity. It accounts for approximately 90% oforal malignancies and impairs appearance, pronunciation, swallowing, and flavor perception...Oral squamous cell carcinoma (OSCC) develops on the mucosal epithelium of the oral cavity. It accounts for approximately 90% oforal malignancies and impairs appearance, pronunciation, swallowing, and flavor perception. In 2020, 377,713 OSCC cases werereported globally. According to the Global Cancer Observatory (GCO), the incidence of OSCC will rise by approximately 40% by2040, accompanied by a growth in mortality. Persistent exposure to various risk factors, including tobacco, alcohol, betel quid (BQ),and human papillomavirus (HPV), will lead to the development of oral potentially malignant disorders (OPMDs), which are oralmucosal lesions with an increased risk of developing into OSCC. Complex and multifactorial, the oncogenesis process involvesgenetic alteration, epigenetic modification, and a dysregulated tumor microenvironment. Although various therapeuticinterventions, such as chemotherapy, radiation, immunotherapy, and nanomedicine, have been proposed to prevent or treat OSCCand OPMDs, understanding the mechanism of malignancies will facilitate the identification of therapeutic and prognostic factors,thereby improving the efficacy of treatment for OSCC patients. This review summarizes the mechanisms involved in OSCC.Moreover, the current therapeutic interventions and prognostic methods for OSCC and OPMDs are discussed to facilitatecomprehension and provide several prospective outlooks for the fields.展开更多
As green tribology is a new field of tribology still in its infancy,understanding its fundamentals is essential for its further development.In this article,a brief historical retrospective on the emergence of green tr...As green tribology is a new field of tribology still in its infancy,understanding its fundamentals is essential for its further development.In this article,a brief historical retrospective on the emergence of green tribology is introduced first,and then the definition,objectives,and disciplinary features of green tribology are clarified.In particular,the technological connotations of green tribology are expounded comprehensively.Also,the developing directions of this new area are envisaged.These findings may contribute to laying the foundation of further advancement in green tribology.展开更多
基金This work was funded by the National Key Research and Development Program of China[Grant Nos.2017YFA0700201 and 2017YFA0303504]National Natural Science Foundation of China[Grant Nos.11734007,91850101,11674068,11874118,and 11474057]Natural Science Foundation of Shanghai[Grant Nos.16ZR1445200,16JC1403100,and 18ZR1403400].
文摘Metasurfaces,ultrathin metamaterials constructed by planar meta-atoms with tailored electromagnetic(EM)responses,have attracted tremendous attention due to their exotic abilities to freely control EM waves.With active elements incorporated into metasurface designs,one can realize tunable and/or reconfgurable metadevices with functionalities controlled by external stimuli,opening a new platform to dynamically manipulate EM waves.In this article,we briefy review recent progress on tunable/reconfgurable metasurfaces,focusing on their working mechanisms and practical applications.We frst describe available approaches,categorized into diferent classes based on external stimuli applied,to realize homogeneous tunable/reconfgurable metasurfaces,which can ofer uniform manipulations on EM waves.We next summarize recent achievements on inhomogeneous tunable/reconfgurable metasurfaces with constitutional meta-atoms locally tuned by external knobs,which can dynamically control the wave-fronts of EM waves.We conclude this review by presenting our own perspectives on possible future directions and existing challenges in this fast developing feld.
基金the National Science Foundation,grant CBET-1032979the Fluid Interfaces Reactions,Structures and Transport(FIRST)+2 种基金funded by the US Department of Energy,Office of Energy,Office of Basic Energy Sciencessupport from a grant from the US Army Research Laboratory through the Collaborative Research Alliance(CRA)for Multi Scale Multidisciplinary Modeling of Electronic Materials(MSME)the Research Board of the Ghent University(BOF)and BELSPO in the frame of IAP/7/05.
文摘The reactive force-field(ReaxFF)interatomic potential is a powerful computational tool for exploring,developing and optimizing material properties.Methods based on the principles of quantum mechanics(QM),while offering valuable theoretical guidance at the electronic level,are often too computationally intense for simulations that consider the full dynamic evolution of a system.Alternatively,empirical interatomic potentials that are based on classical principles require significantly fewer computational resources,which enables simulations to better describe dynamic processes over longer timeframes and on larger scales.Such methods,however,typically require a predefined connectivity between atoms,precluding simulations that involve reactive events.The ReaxFF method was developed to help bridge this gap.Approaching the gap from the classical side,ReaxFF casts the empirical interatomic potential within a bond-order formalism,thus implicitly describing chemical bonding without expensive QM calculations.This article provides an overview of the development,application,and future directions of the ReaxFF method.
文摘Hepatocellular carcinoma(HCC) is the most common type of primary liver cancer, which in turns accounts for the sixth most common cancer worldwide.Despite being the 6 th most common cancer it is the second leading cause of cancer related deaths. HCC typically arises in the background of cirrhosis, however,about 20% of cases can develop in a non-cirrhotic liver. This particular subgroup of HCC generally presents at an advanced stage as surveillance is not performed in a non-cirrhotic liver. HCC in non-cirrhotic patients is clinically silent in its early stages because of lack of symptoms and surveillance imaging; and higher hepatic reserve in this population. Interestingly, F3 fibrosis in non-alcoholic fatty liver disease, hepatitis B virus and hepatitis C virus infections are associated with high risk of developing HCC. Even though considerable progress has been made in the management of this entity, there is a dire need for implementation of surveillance strategies in the patient population at risk, to decrease the disease burden at presentation and improve the prognosis of these patients. This comprehensive review details the epidemiology, risk factors, clinical features,diagnosis and management of HCC in non-cirrhotic patients and provides future directions for research.
基金We are grateful to the Laboratory Directed Research and Development(LDRD)program(project#20180660ER)the Center for Nonlinear Studies at Los Alamos National Laboratory for support.
文摘One of the main challenges in materials discovery is efficiently exploring the vast search space for targeted properties as approaches that rely on trial-and-error are impractical.We review how methods from the information sciences enable us to accelerate the search and discovery of new materials.In particular,active learning allows us to effectively navigate the search space iteratively to identify promising candidates for guiding experiments and computations.The approach relies on the use of uncertainties and making predictions from a surrogate model together with a utility function that prioritizes the decision making process on unexplored data.We discuss several utility functions and demonstrate their use in materials science applications,impacting both experimental and computational research.We summarize by indicating generalizations to multiple properties and multifidelity data,and identify challenges,future directions and opportunities in the emerging field of materials informatics.
基金supported by the National Natural Science Foundation of China under Contract No.11575194.
文摘Pulsed discharge plasma and its application is one of the promising directions in civilian areas of pulsed power technology.In order to promote the research and development of the theory and application technology for pulsed discharge plasma,in this paper,recent progress on the mechanism of nanosecond-pulse gas discharge and the characteristics and applications of typical pulsed plasma at the Institute of Electrical Engineering,Chinese Academy of Sciences is reviewed.Firstly,progress on mechanism of nanosecond-pulse discharge based on runaway electrons and measurement technology of runaway electrons is introduced.Then,the characteristics of three typical discharges,including direct-driven pulsed discharge,pulsed dielectric barrier discharge and pulsed plasma jet,are reviewed.Furthermore,typical plasma applications of pulsed plasma on surface modification and methane conversion are presented.
文摘To date,the coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has determined 399,600,607 cases and 5,757,562 deaths worldwide.COVID-19 is a serious threat to human health globally.The World Health Organization(WHO)has declared COVID-19 pandemic a major public health emergency.Vaccination is the most effective and economical intervention for controlling the spread of epidemics,and consequently saving lives and protecting the health of the population.Various techniques have been employed in the development of COVID-19 vaccines.Among these,the COVID-19 messenger RNA(mRNA)vaccine has been drawing increasing attention owing to its great application prospects and advantages,which include short development cycle,easy industrialization,simple production process,flexibility to respond to new variants,and the capacity to induce better immune response.This review summarizes current knowledge on the structural characteristics,antigen design strategies,delivery systems,industrialization potential,quality control,latest clinical trials and real-world data of COVID-19 mRNA vaccines as well as mRNA technology.Current challenges and future directions in the development of preventive mRNA vaccines for major infectious diseases are also discussed.
基金Project supported by the National Natural Science Foundation of China(Nos.11372252 and 11402035)
文摘The in-plane dynamic crushing behavior of re-entrant honeycomb is analyzed and compared with the conventional hexagon topology.Detailed deformation modes along two orthogonal directions are examined,where a parametric study of the effect of impact velocity and cell wall aspect ratio is performed.An analytical formula of the dynamic crushing strength is then deduced based on the periodic collapse mechanism of cell structures.Comparisons with the finite element results validate the effectiveness of the proposed analytical method.Numerical results also reveal higher plateau stress of re-entrant honeycomb over conventional hexagon topology,implying better energy absorption properties.The underlying physical understanding of the results is emphasized,where the auxetic effect（negative Poisson＇s ratio） induced in the re-entrant topology is believed to be responsible for this superior impact resistance.
基金Under the auspices of National Natural Science Foundation of China(No.40971101)Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences(No.KZC X2-YW-321-05)
文摘Regional inequality is a core issue in geography,and it can be measured by several approaches and indexes.However,the global inequality measures can not reflect regional characteristics in terms of spatiality and non-mobility,as well as correctly explore regional inequality in particular directions.Although conventional between-group inequality indexes can measure the inequality in particular directions,they can not reflect the reversals of regional patterns and changes of within-group patterns.Therefore,we set forth a new approach to measure regional inequality in particular directions,which is applicable to geographic field.Based on grouping,we established a new index to measure regional inequality in particular directions named Particular Direction Inequality index(PDI index),which is comprised of between-group inequality of all data and between-group average gap.It can reflect regional spatiality and non-mobility,judge the main direction of regional inequality,and capture the changes and reversals of regional patterns.We used the PDI index to measure the changes of regional inequality from 1952 to 2009 in China.The results show that:1) the main direction of China's regional inequality was between coastal areas and inland areas;the increasing extent of inequality between coastal areas and inland areas was higher than the global inequality;2) the PDI index can measure the between-region average gap,and is more sensitive to evolution of within-region patterns;3) the inequality between the northern China and the southern China has been decreasing from 1952 to 2009 and was reversed in 1994 and 1995.
基金This work was supported by the National Key Research Project of China(2016YFC0501505)the National Natural Science Foundation of China(CN)(31572091,31730080).
文摘Flavonoids play essential roles in human health.Apple(Malus domestica Borkh.),one of the most widely produced and economically important fruit crops in temperate regions,is a significant source of flavonoids in the human diet and is among the top nutritionally rated and most widely consumed fruits worldwide.Epidemiological studies have shown that the consumption of apples,which are rich in a variety of free and easily absorbable flavonoids,is associated with a decreased risk of various diseases.However,apple production is challenged by serious inbreeding problems.The narrowing of the hereditary base has resulted in apples with poor nutritional quality and low flavonoid contents.Recently,there have been advances in our understanding of the roles that Malus sieversii(Ledeb.)M.Roem has played in the process of apple domestication and breeding.In this study,we review the origin of cultivated apples and red-fleshed apples,and discuss the genetic diversity and construction of the core collections of M.sieversii.We also discuss current research progress and breeding programs on red-skinned and red-fleshed apples and summarize the exploitation and utilization of M.sieversii in the breeding of high-flavonoid,and red-fleshed apples.This study highlights a valuable pattern of horticultural crop breeding using wild germplasm resources.The future challenges and directions of research on the molecular mechanisms of flavonoid accumulation and high-flavonoid apple breeding are discussed.
文摘The article explores the issue of designing a new design of a loading cylinder with a casing filled with vulcanized rubber for pneumomechanical spinning machines. The theoretical calculation of the deformed state of a cylindrical shell filled with vulcanized rubber is given. Deflections and stresses in the rubber layer are determined, which we use approximately for the Ritz methods. The theory of the radial and axial moving rubber layer was analyzed. The specific energy of deformation of a cylindrical layer of a compound cylinder is determined. The statics of the case and the loading cylinder of spinning machines are thoroughly studied.
基金supported by the National Key Research and Development Project of China (2020YFA0509400)Guangdong Basic and Applied Basic Research Foundation(2019B030302012)+1 种基金National Natural Science Foundation of China (81821002, 82130082)1·3·5 project for disciplines of excellence (ZYGD22007,ZYGC21004)
文摘Oral squamous cell carcinoma (OSCC) develops on the mucosal epithelium of the oral cavity. It accounts for approximately 90% oforal malignancies and impairs appearance, pronunciation, swallowing, and flavor perception. In 2020, 377,713 OSCC cases werereported globally. According to the Global Cancer Observatory (GCO), the incidence of OSCC will rise by approximately 40% by2040, accompanied by a growth in mortality. Persistent exposure to various risk factors, including tobacco, alcohol, betel quid (BQ),and human papillomavirus (HPV), will lead to the development of oral potentially malignant disorders (OPMDs), which are oralmucosal lesions with an increased risk of developing into OSCC. Complex and multifactorial, the oncogenesis process involvesgenetic alteration, epigenetic modification, and a dysregulated tumor microenvironment. Although various therapeuticinterventions, such as chemotherapy, radiation, immunotherapy, and nanomedicine, have been proposed to prevent or treat OSCCand OPMDs, understanding the mechanism of malignancies will facilitate the identification of therapeutic and prognostic factors,thereby improving the efficacy of treatment for OSCC patients. This review summarizes the mechanisms involved in OSCC.Moreover, the current therapeutic interventions and prognostic methods for OSCC and OPMDs are discussed to facilitatecomprehension and provide several prospective outlooks for the fields.
文摘As green tribology is a new field of tribology still in its infancy,understanding its fundamentals is essential for its further development.In this article,a brief historical retrospective on the emergence of green tribology is introduced first,and then the definition,objectives,and disciplinary features of green tribology are clarified.In particular,the technological connotations of green tribology are expounded comprehensively.Also,the developing directions of this new area are envisaged.These findings may contribute to laying the foundation of further advancement in green tribology.
