Metallic clusters,ranging from 1 to 2 nm in size,have emerged as promising candidates for creating nanoelectronic devices at the single-cluster level.With the intermediate quantum properties between metals and semicon...Metallic clusters,ranging from 1 to 2 nm in size,have emerged as promising candidates for creating nanoelectronic devices at the single-cluster level.With the intermediate quantum properties between metals and semiconductors,these metallic clusters offer an alternative pathway to silicon-based electronics and organic molecules for miniaturized electronics with dimensions below 5 nm.Significant progress has been made in studies of single-cluster electronic devices.However,a clear guide for selecting,synthesizing,and fabricating functional single-cluster electronic devices is still required.This review article provides a comprehensive overview of single-cluster electronic devices,including the mechanisms of electron transport,the fabrication of devices,and the regulations of electron transport properties.Furthermore,we discuss the challenges and future directions for single-cluster electronic devices and their potential applications.展开更多
Optical vortices,which carry orbital angular momentum,offer special capabilities in a host of applications.A single-laser source with dual-beam-mode output may open up new research fields of nonlinear optics and quant...Optical vortices,which carry orbital angular momentum,offer special capabilities in a host of applications.A single-laser source with dual-beam-mode output may open up new research fields of nonlinear optics and quantum optics.We demonstrate a dual-channel scheme to generate femtosecond,dualwavelength,and dual-beam-mode tunable signals in the near infrared wavelength range.Dual-wavelength operation is derived by stimulating two adjacent periods of a periodically poled lithium niobate crystal.Pumped by an Yb-doped fiber laser with a Gaussian(lp?0)beam,two tunable signal emissions with different beam modes are observed simultaneously.Although one of the emissions can be tuned from1520 to 1613 nm with the Gaussian(ls?0)beam,the other is capable of producing a vortex spatial profile with different vortex orders(ls?0 to 2)tunable from 1490 to 1549 nm.The proposed system provides unprecedented freedom and will be an exciting platform for super-resolution imaging,nonlinear optics,multidimensional quantum entanglement,etc.展开更多
Since 2019 humanity has been subjected to the perturbations of pandemic,economic disruption,war,civil unrest and changes in whole-Earth dynamics associated with a human-induced Anthropocene.Each perturbation is like a...Since 2019 humanity has been subjected to the perturbations of pandemic,economic disruption,war,civil unrest and changes in whole-Earth dynamics associated with a human-induced Anthropocene.Each perturbation is like a wave-front breaking on the shore of our historical ways of thinking and acting,increasingly unfit for our human circumstances.This challenge to humanity is not new.In 1970 the French term‘problematique’was coined to refer to a set of 49 interrelated global problems;the classic description of wicked and tame problems was published soon after,yet little progress has been made towards answering the question:what purposeful action will aid human flourishing,create and sustain a viable space for humanity,in our ongoing co-evolution with the Anthropocene-Biosphere?A case for innovation in our ways of knowing and doing is made based on arguments that our social world is constrained by:(i)explanations we accept that are no longer relevant to our circumstances;(ii)outdated historical institutions(in the institutional economics sense)that contribute as social technologies to a broader human created and ungoverned technosphere;(iii)inadequate theory-informed practices,or praxis,and(iv)governance-systems no longer adequate for purpose.Practitioners of knowledge science and systems science are urged to act reflexively to critically evaluate the traditions-of-understanding out of which they think and act.展开更多
采用熔化极活性气体保护焊(metal active gas arc welding,MAG焊)、等离子弧焊(plasma arc welding,PAW)和高频感应焊接方法获得铁素体+马氏体双相组织不锈钢00Cr12Ni的焊接接头,对其组织区域特征和力学性能进行了研究.典型的焊接接头...采用熔化极活性气体保护焊(metal active gas arc welding,MAG焊)、等离子弧焊(plasma arc welding,PAW)和高频感应焊接方法获得铁素体+马氏体双相组织不锈钢00Cr12Ni的焊接接头,对其组织区域特征和力学性能进行了研究.典型的焊接接头热影响区(heat affected zone,HAZ)可分为晶粒粗大,铁素体为优势相的高温热影响区(high temperature heat affected zone,HTHAZ)和晶粒细小,马氏体为优势相的低温热影响区(low temperature heat affected zone,LTHAZ).通过测量实际焊接热循环曲线的方法确定了HTHAZ及LTHAZ的温度范围,并采用热模拟研究HAZ不同区域的力学性能.结果表明,HTHAZ的热循环峰值范围为1200℃至熔点,晶粒粗大呈现为脆性;LTHAZ热循环峰值范围为800~1200℃,室温组织为非平衡低碳板条马氏体,韧性较好,但低于0℃时呈脆性.MAG焊接头由于奥氏体焊缝为钟罩形,HAZ冲击试验时断面包括奥氏体焊缝,因此冲击性能较好;PAW接头在1000℃奥氏体快冷可获得细晶粒马氏体韧性提高;高频感应焊接接头中无HTHAZ,但焊接过程中的加工硬化导致室温呈脆性,通过去应力退火后韧性恢复.展开更多
The demand for miniaturization and integration of optical elements has fostered the development of various micro-and nanofabrication technologies.In this work,we developed a low-cost UV-LED-based microscope projection...The demand for miniaturization and integration of optical elements has fostered the development of various micro-and nanofabrication technologies.In this work,we developed a low-cost UV-LED-based microscope projection photolithography system for rapid and high-resolution fabrication.This system can be easily implemented using off-the-shelf components.It allows for micro-and nanostructuring within seconds.By optimizing the process,a minimum feature size down to approximately 85 nm was successfully realized.In addition,investigations on fabrication of the same structures using both costly and economic microscope objectives were performed.Feature sizes below 100 nm can be stably achieved.The demonstrated approach extends the technology capabilities and may find applications in fields such as nanophotonics,biophotonics sensing and material science.展开更多
The advancement of micro-and nanostructuring techniques in optics is driven by the demand for continuous miniaturization and the high geometrical accuracy of photonic devices and integrated systems.Here,UV-LED project...The advancement of micro-and nanostructuring techniques in optics is driven by the demand for continuous miniaturization and the high geometrical accuracy of photonic devices and integrated systems.Here,UV-LED projection photolithography is demonstrated as a simple and low-cost approach for rapid generation of two-dimensional optical micro-and nanostructures with high resolution and accuracy using standard optics only.The developed system enables the projection of structure patterns onto a substrate with 1000-fold demagnification.Photonic devices,e.g.,waveguides and microring resonators,on rigid or flexible substrates with varied geometrical complexity and overall structure dimensions from the nanometer to centimeter scale were successfully prepared.In particular,high-resolution gratings with feature sizes down to 150 nm and periods as small as 400 nm were realized for the first time by this approach.Waveguides made of doped laser active materials were fabricated,and their spontaneous emission was detected.The demonstrated superior performance of the developed approach may find wide applications in photonics,plasmonics,and optical materials science,among others.展开更多
In modern physics and fabrication technology,simulation of projectile and target collision is vital to improve design in some critical applications,like;bulletproofing and medical applications.Graphene,the most promin...In modern physics and fabrication technology,simulation of projectile and target collision is vital to improve design in some critical applications,like;bulletproofing and medical applications.Graphene,the most prominent member of two dimensional materials presents ultrahigh tensile strength and stiffness.Moreover,polydimethylsiloxane(PDMS)is one of the most important elastomeric materials with a high extensive application area,ranging from medical,fabric,and interface material.In this work we considered graphene/PDMS structures to explore the bullet resistance of resulting nanocomposites.To this aim,extensive molecular dynamic simulations were carried out to identify the penetration of bullet through the graphene and PDMS composite structures.In this paper,we simulate the impact of a diamond bullet with different velocities on the composites made of single-or bi-layer graphene placed in different positions of PDMS polymers.The underlying mechanism concerning how the PDMS improves the resistance of graphene against impact loading is discussed.We discuss that with the same content of graphene,placing the graphene in between the PDMS result in enhanced bullet resistance.This work comparatively examines the enhancement in design of polymer nanocomposites to improve their bulletproofing response and the obtained results may serve as valuable guide for future experimental and theoretical studies.展开更多
The pinning of quantized magnetic vortices in superconducting YBa_(2)Cu_(3)O_(7-δ)(YBCO or Y123)thin films with Y_(2)BaCuO_(5)(Y211)nanoinclusions have been investigated over wide temperature range(4.2-77 K).The conc...The pinning of quantized magnetic vortices in superconducting YBa_(2)Cu_(3)O_(7-δ)(YBCO or Y123)thin films with Y_(2)BaCuO_(5)(Y211)nanoinclusions have been investigated over wide temperature range(4.2-77 K).The concentration of Y211 nanoinclusions has been systematically varied inside YBCO thin films prepared by laser ablation technique using surface modified target approach.Large pinning force density values(Fp∼0.5 TNm^(−3)at 4.2 K,9 T)have been observed for the YBCO film with moderate concentration of Y211 nanoinclusions(3.6 area%on ablation target).In addition,uniform enhancement in critical current density(J_(c))was observed in the angular dependent J_(c)measurement of YBCO+Y211 nanocomposite films.Y211 nanoinclusions have been found to be very efficient in pinning the quantized vortices thereby enhancing the in‐field J_(c)values over a wide range of temperature.Increasing the concentration of Y211 secondary phase into Y123 film matrix results into agglomeration of Y211 phase and observed as increased Y211 nanoparticle size.These larger secondary phase nanoparticles are not as efficient pinning centers at lower temperatures as they are at higher temperatures due to substantial reduction of the coherence length at lower temperatures.Investigation of the temperature dependence of J_(c)for YBCO+Y211 nanocomposite films has been conducted and possible vortex pinning mechanism in these nanocomposite films has been discussed.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22250003,22173075,21933012,and 22003052)the Fundamental Research Funds for the Central Universities(Nos.20720220020,20720220072,and 20720200068).
文摘Metallic clusters,ranging from 1 to 2 nm in size,have emerged as promising candidates for creating nanoelectronic devices at the single-cluster level.With the intermediate quantum properties between metals and semiconductors,these metallic clusters offer an alternative pathway to silicon-based electronics and organic molecules for miniaturized electronics with dimensions below 5 nm.Significant progress has been made in studies of single-cluster electronic devices.However,a clear guide for selecting,synthesizing,and fabricating functional single-cluster electronic devices is still required.This review article provides a comprehensive overview of single-cluster electronic devices,including the mechanisms of electron transport,the fabrication of devices,and the regulations of electron transport properties.Furthermore,we discuss the challenges and future directions for single-cluster electronic devices and their potential applications.
基金support by the National Natural Science Foundation of China(NSFC)(Nos.61535009 and 6182781)the Tianjin Research Program of Application Foundation and Advanced Technology(No.17JCJQJC43500)
文摘Optical vortices,which carry orbital angular momentum,offer special capabilities in a host of applications.A single-laser source with dual-beam-mode output may open up new research fields of nonlinear optics and quantum optics.We demonstrate a dual-channel scheme to generate femtosecond,dualwavelength,and dual-beam-mode tunable signals in the near infrared wavelength range.Dual-wavelength operation is derived by stimulating two adjacent periods of a periodically poled lithium niobate crystal.Pumped by an Yb-doped fiber laser with a Gaussian(lp?0)beam,two tunable signal emissions with different beam modes are observed simultaneously.Although one of the emissions can be tuned from1520 to 1613 nm with the Gaussian(ls?0)beam,the other is capable of producing a vortex spatial profile with different vortex orders(ls?0 to 2)tunable from 1490 to 1549 nm.The proposed system provides unprecedented freedom and will be an exciting platform for super-resolution imaging,nonlinear optics,multidimensional quantum entanglement,etc.
文摘Since 2019 humanity has been subjected to the perturbations of pandemic,economic disruption,war,civil unrest and changes in whole-Earth dynamics associated with a human-induced Anthropocene.Each perturbation is like a wave-front breaking on the shore of our historical ways of thinking and acting,increasingly unfit for our human circumstances.This challenge to humanity is not new.In 1970 the French term‘problematique’was coined to refer to a set of 49 interrelated global problems;the classic description of wicked and tame problems was published soon after,yet little progress has been made towards answering the question:what purposeful action will aid human flourishing,create and sustain a viable space for humanity,in our ongoing co-evolution with the Anthropocene-Biosphere?A case for innovation in our ways of knowing and doing is made based on arguments that our social world is constrained by:(i)explanations we accept that are no longer relevant to our circumstances;(ii)outdated historical institutions(in the institutional economics sense)that contribute as social technologies to a broader human created and ungoverned technosphere;(iii)inadequate theory-informed practices,or praxis,and(iv)governance-systems no longer adequate for purpose.Practitioners of knowledge science and systems science are urged to act reflexively to critically evaluate the traditions-of-understanding out of which they think and act.
文摘采用熔化极活性气体保护焊(metal active gas arc welding,MAG焊)、等离子弧焊(plasma arc welding,PAW)和高频感应焊接方法获得铁素体+马氏体双相组织不锈钢00Cr12Ni的焊接接头,对其组织区域特征和力学性能进行了研究.典型的焊接接头热影响区(heat affected zone,HAZ)可分为晶粒粗大,铁素体为优势相的高温热影响区(high temperature heat affected zone,HTHAZ)和晶粒细小,马氏体为优势相的低温热影响区(low temperature heat affected zone,LTHAZ).通过测量实际焊接热循环曲线的方法确定了HTHAZ及LTHAZ的温度范围,并采用热模拟研究HAZ不同区域的力学性能.结果表明,HTHAZ的热循环峰值范围为1200℃至熔点,晶粒粗大呈现为脆性;LTHAZ热循环峰值范围为800~1200℃,室温组织为非平衡低碳板条马氏体,韧性较好,但低于0℃时呈脆性.MAG焊接头由于奥氏体焊缝为钟罩形,HAZ冲击试验时断面包括奥氏体焊缝,因此冲击性能较好;PAW接头在1000℃奥氏体快冷可获得细晶粒马氏体韧性提高;高频感应焊接接头中无HTHAZ,但焊接过程中的加工硬化导致室温呈脆性,通过去应力退火后韧性恢复.
基金the financial support from the German Research Foundation(DFG)under Germany’s Excellence Strategy within the Cluster of Excellence PhoenixD(EXC 2122,Project ID 390833453).
文摘The demand for miniaturization and integration of optical elements has fostered the development of various micro-and nanofabrication technologies.In this work,we developed a low-cost UV-LED-based microscope projection photolithography system for rapid and high-resolution fabrication.This system can be easily implemented using off-the-shelf components.It allows for micro-and nanostructuring within seconds.By optimizing the process,a minimum feature size down to approximately 85 nm was successfully realized.In addition,investigations on fabrication of the same structures using both costly and economic microscope objectives were performed.Feature sizes below 100 nm can be stably achieved.The demonstrated approach extends the technology capabilities and may find applications in fields such as nanophotonics,biophotonics sensing and material science.
基金support from the German Research Foundation(DFG)under Germany's Excellence Strategy within the Cluster of Excellence PhoenixD(EXC 2122,Project ID 390833453)the DFG(German Research Foundation,Project ID RE3012/4-1 and RE3012/2-1).
文摘The advancement of micro-and nanostructuring techniques in optics is driven by the demand for continuous miniaturization and the high geometrical accuracy of photonic devices and integrated systems.Here,UV-LED projection photolithography is demonstrated as a simple and low-cost approach for rapid generation of two-dimensional optical micro-and nanostructures with high resolution and accuracy using standard optics only.The developed system enables the projection of structure patterns onto a substrate with 1000-fold demagnification.Photonic devices,e.g.,waveguides and microring resonators,on rigid or flexible substrates with varied geometrical complexity and overall structure dimensions from the nanometer to centimeter scale were successfully prepared.In particular,high-resolution gratings with feature sizes down to 150 nm and periods as small as 400 nm were realized for the first time by this approach.Waveguides made of doped laser active materials were fabricated,and their spontaneous emission was detected.The demonstrated superior performance of the developed approach may find wide applications in photonics,plasmonics,and optical materials science,among others.
基金B.M.and X.Z.appreciate the funding by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy within the Cluster of Excellence PhoenixD(EXC 2122,Project ID 390833453).
文摘In modern physics and fabrication technology,simulation of projectile and target collision is vital to improve design in some critical applications,like;bulletproofing and medical applications.Graphene,the most prominent member of two dimensional materials presents ultrahigh tensile strength and stiffness.Moreover,polydimethylsiloxane(PDMS)is one of the most important elastomeric materials with a high extensive application area,ranging from medical,fabric,and interface material.In this work we considered graphene/PDMS structures to explore the bullet resistance of resulting nanocomposites.To this aim,extensive molecular dynamic simulations were carried out to identify the penetration of bullet through the graphene and PDMS composite structures.In this paper,we simulate the impact of a diamond bullet with different velocities on the composites made of single-or bi-layer graphene placed in different positions of PDMS polymers.The underlying mechanism concerning how the PDMS improves the resistance of graphene against impact loading is discussed.We discuss that with the same content of graphene,placing the graphene in between the PDMS result in enhanced bullet resistance.This work comparatively examines the enhancement in design of polymer nanocomposites to improve their bulletproofing response and the obtained results may serve as valuable guide for future experimental and theoretical studies.
基金supported by the ALCA project of Japan Science and Technology Agency.
文摘The pinning of quantized magnetic vortices in superconducting YBa_(2)Cu_(3)O_(7-δ)(YBCO or Y123)thin films with Y_(2)BaCuO_(5)(Y211)nanoinclusions have been investigated over wide temperature range(4.2-77 K).The concentration of Y211 nanoinclusions has been systematically varied inside YBCO thin films prepared by laser ablation technique using surface modified target approach.Large pinning force density values(Fp∼0.5 TNm^(−3)at 4.2 K,9 T)have been observed for the YBCO film with moderate concentration of Y211 nanoinclusions(3.6 area%on ablation target).In addition,uniform enhancement in critical current density(J_(c))was observed in the angular dependent J_(c)measurement of YBCO+Y211 nanocomposite films.Y211 nanoinclusions have been found to be very efficient in pinning the quantized vortices thereby enhancing the in‐field J_(c)values over a wide range of temperature.Increasing the concentration of Y211 secondary phase into Y123 film matrix results into agglomeration of Y211 phase and observed as increased Y211 nanoparticle size.These larger secondary phase nanoparticles are not as efficient pinning centers at lower temperatures as they are at higher temperatures due to substantial reduction of the coherence length at lower temperatures.Investigation of the temperature dependence of J_(c)for YBCO+Y211 nanocomposite films has been conducted and possible vortex pinning mechanism in these nanocomposite films has been discussed.
