光电振荡器是一种能够稳定产生自激振荡的微波光子共振系统,近年来得到了广泛的研究,工作频率达到数百GHz,相位噪声性能达到-163 dBc/Hz at 6 kHz,调谐范围达到数十千兆赫兹。文章回顾了光电振荡器问世以来的部分研究进展和重要应用,重...光电振荡器是一种能够稳定产生自激振荡的微波光子共振系统,近年来得到了广泛的研究,工作频率达到数百GHz,相位噪声性能达到-163 dBc/Hz at 6 kHz,调谐范围达到数十千兆赫兹。文章回顾了光电振荡器问世以来的部分研究进展和重要应用,重点介绍了近年来集成化光电振荡器的研究现状,并提出了一种可应用于集成化光电振荡器的新型电光晶体材料。展开更多
Kitaev quantum spin liquids have attracted significant attention in condensed matter physics over the past decade.To understand their emergent quantum phenomena,high-quality single crystals of substantial size are ess...Kitaev quantum spin liquids have attracted significant attention in condensed matter physics over the past decade.To understand their emergent quantum phenomena,high-quality single crystals of substantial size are essential.Here,we report the synthesis of single crystals of the Kitaev quantum spin liquid candidate RuBr_(3),achieving millimeter-sized crystals through a self-flux method under high pressure and high temperature conditions.The crystals exhibit well-defined cleavage planes with a lustrous appearance.Transport characterizations exhibit a narrow band-gap semiconducting behavior with 0.13 eV and 0.11 eV band-gap in ab plane and along𝑐axis,respectively.Magnetic measurement shows a transition to antiferromagnetic(AFM)state at approximately 29K both in ab plane and along the c axis.Notably,the N′eel temperature increases to 34K with an applied magnetic field of up to 7T in the ab plane,but without any change along𝑐axis.The large size and high quality of RuBr3 single crystals provide a valuable platform for investigating various interactions,particularly the Kitaev interaction,and for elucidating the intrinsic physical properties of Kitaev quantum spin liquids.展开更多
A"verdict"on the economic value of the patent system by the US economist Fritz Machlup published in 1958 still has an important impact on assessing the effects of the patent system on economic development by...A"verdict"on the economic value of the patent system by the US economist Fritz Machlup published in 1958 still has an important impact on assessing the effects of the patent system on economic development by intellec-tual property scholars worldwide.This contribution analyses Machlup's study as is and in the light of subsequent US and global legal and economic developments.Machlup's assessment was examined based on empirical data generated by the US Bayh-Dole type legislation as regards the translation of basic research into innovative products and pro-cesses.Moreover,it analyses the impact of the new world economic order instituted in the framework of the World Trade Organization(WTO)mandatorily requiring effective patent protection in all WTO Member States on the eco-nomic development of developing and emerging economies.The case of China,which adopted its first Patent Law in 1984,is addressed in the context of Machlup's verdict and in light of the subsequent economic,scientific and techno-logical development of that country.Concluding thoughts consider today's value of Machlup's"verdict".展开更多
Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and ...Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and related deformation mechanisms is crucial for their structural applications,particularly in the lightweight transportation industries.Nevertheless,the underlying deformation mechanisms(e.g.,slip versus twinning)at each deformation stage during tension and compression have not been fully understood.In this study,we employed tensile and compressive tests on extruded Al and Mn containing Mg alloy,i.e.,an AM alloy Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca,during the synchrotron X-ray diffraction.Our results show that distinct deformation behaviors and mechanisms in tension and compression are associated with the strong texture in the extruded samples:(i)The tensile deformation is dominated by dislocation slips,with activation of non-basaland<c+a>slip,but deformation twinning is suppressed.(ii)The compressive deformation shows early-stage tensile twinning,followed by dislocation slips.Twinning induces grain reorientation,leading to significant lattice strain evolution aligned with the texture.The pronounced tension-compression asymmetry is attributed to the favorable shear stress direction formed in the twinning system during compression,which facilitates the activation of tensile twins.During tension,the strain hardening rate(SHR)drops significantly after yielding due to limited activated slip systems.In contrast,the samples under compression exhibit significant increases in SHR after yielding.During compression,dislocation multiplication dominates the initial strain hardening,while twinning progressively contributes more significantly than dislocation slip at higher strains.This study improves our understanding of the tension-compression and strain hardening asymmetries in extruded AM Mg alloys.展开更多
Plasma electrolytic oxidation(PEO)processing of light metals has been established for decades and is in increasing industrial use,even as an alternative surface treatment to produce multifunctional coatings with envir...Plasma electrolytic oxidation(PEO)processing of light metals has been established for decades and is in increasing industrial use,even as an alternative surface treatment to produce multifunctional coatings with environmental-friendly processing concept.One of the benefits of PEO processing claimed already a couple of years ago was the ability to treat dissimilar metal joints,which can obviously improve the surface homogeneity and stability at the interface of the dissimilar components,especially impeding the galvanic corrosion due to the different electrochemical properties of each component.However,the progress and breakthrough develop slowly especially for the macro scales due to the much larger gap between each component.This literature review firstly demonstrates the still low number of studies reporting successful PEO treatment of material combination such as Mg/Al,Mg/Ti,Al/Ti and scarcely light metal combinations with steel.The main issues and challenges to performing PEO processing on the macroscale dissimilar weldments were stated.On the other hand,dissimilar metal joints also widely exist in micrometer scale in alloys and metal matrix composites(MMCs).Moreover,there is a huge knowledge base on PEO treatment of such multiphase substrates.PEO processing of such complicated mixed microstructures is reviewed as well to reveal the basic problems.To some certain degree,these PEO-related studies on alloys and MMCs can be good examples to have an insight into the coating formation mechanism on macro-scaled dissimilar metal joints.Conclusions are drawn from the micro-to macroscale.Finally,critical access to the problems is given and possible solutions and reaming limitations are discussed.展开更多
In-situ growth of layered double hydroxide(LDH)has been considered a feasible method to further improve the corrosion protection of PEO coated Mg alloys,but the process is basically carried out in an autoclave.In this...In-situ growth of layered double hydroxide(LDH)has been considered a feasible method to further improve the corrosion protection of PEO coated Mg alloys,but the process is basically carried out in an autoclave.In this study,LDH was in-situ synthesized on PEO treated AM50 Mg by hydrothermal treatment at ambient pressure in the presence of chelating agents.Results indicated that the synergistic effect of sulfosalicylic acid(SSA)and ethylenediaminetetraacetic acid tetrasodium salt(EDTA)chelating agents is appropriate for Mg-Al LDH formation due to the sufficient quantity of highly stable Mg and Al complexes in the treatment bath.An appropriate hydrothermal treatment time was also revealed in this work,which can efficiently seal the pores and defects of PEO coating with a uniform LDH film.As a result,the corrosion protection of the coating was improved dramatically.The prolonged hydrothermal treatment is detrimental to the integrity of PEO layers.The influence of chelating agents on the LDH formation processes is supported by thermodynamic calculation of the equilibrium composition,and the formation mechanism of LDH film is discussed in depth.展开更多
Heterogeneous catalysis on solid surfaces provides high-value chemicals and is involved in a large fraction of the world’s economic productivity,yet our understanding of this important class of processes remains limi...Heterogeneous catalysis on solid surfaces provides high-value chemicals and is involved in a large fraction of the world’s economic productivity,yet our understanding of this important class of processes remains limited.Thermal reaction rates obtained from experiments on mod-el catalysts provide quantitative data that can reveal reaction mechanisms and provide benchmarks for computational simulations of catalytic processes.This perspective describes a critical advance in measuring these rates:velocity resolved kinetics(VRK).VRK delivers ab-solute rates for elementary surface reactions that are of sufficient accuracy that they may be meaningfully compared to theoretical rate predictions,creating a powerful synergy between theory and experiment.It is now routinely possible to derive fundamental thermochemical quantities,including desorption and adsorption energies,reaction barrier heights,diffusion barrier heights,and lateral adsorbate interaction energies.Reaction mechanisms can also be revealed and reaction intermediates directly detected.The high time resolution of VRK al-lows study of catalytic reactions at the high temperatures typical of conditions present in real catalytic reactors.Current work exploiting the newest and by far the most powerful variant of VRK has only scratched the surface of what is possible,signifying a promising future for re-searchers in this field.展开更多
文摘光电振荡器是一种能够稳定产生自激振荡的微波光子共振系统,近年来得到了广泛的研究,工作频率达到数百GHz,相位噪声性能达到-163 dBc/Hz at 6 kHz,调谐范围达到数十千兆赫兹。文章回顾了光电振荡器问世以来的部分研究进展和重要应用,重点介绍了近年来集成化光电振荡器的研究现状,并提出了一种可应用于集成化光电振荡器的新型电光晶体材料。
基金supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406000 and 2022YFA1403800)the National Natural Science Foundation of China(Grant Nos.12474002,22171283,22203031,12434005,12204515,and 12074175)support of the Young Elite Scientists Sponsorship Program by CAST(Grant No.2022QNRC001)。
文摘Kitaev quantum spin liquids have attracted significant attention in condensed matter physics over the past decade.To understand their emergent quantum phenomena,high-quality single crystals of substantial size are essential.Here,we report the synthesis of single crystals of the Kitaev quantum spin liquid candidate RuBr_(3),achieving millimeter-sized crystals through a self-flux method under high pressure and high temperature conditions.The crystals exhibit well-defined cleavage planes with a lustrous appearance.Transport characterizations exhibit a narrow band-gap semiconducting behavior with 0.13 eV and 0.11 eV band-gap in ab plane and along𝑐axis,respectively.Magnetic measurement shows a transition to antiferromagnetic(AFM)state at approximately 29K both in ab plane and along the c axis.Notably,the N′eel temperature increases to 34K with an applied magnetic field of up to 7T in the ab plane,but without any change along𝑐axis.The large size and high quality of RuBr3 single crystals provide a valuable platform for investigating various interactions,particularly the Kitaev interaction,and for elucidating the intrinsic physical properties of Kitaev quantum spin liquids.
文摘A"verdict"on the economic value of the patent system by the US economist Fritz Machlup published in 1958 still has an important impact on assessing the effects of the patent system on economic development by intellec-tual property scholars worldwide.This contribution analyses Machlup's study as is and in the light of subsequent US and global legal and economic developments.Machlup's assessment was examined based on empirical data generated by the US Bayh-Dole type legislation as regards the translation of basic research into innovative products and pro-cesses.Moreover,it analyses the impact of the new world economic order instituted in the framework of the World Trade Organization(WTO)mandatorily requiring effective patent protection in all WTO Member States on the eco-nomic development of developing and emerging economies.The case of China,which adopted its first Patent Law in 1984,is addressed in the context of Machlup's verdict and in light of the subsequent economic,scientific and techno-logical development of that country.Concluding thoughts consider today's value of Machlup's"verdict".
文摘Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and related deformation mechanisms is crucial for their structural applications,particularly in the lightweight transportation industries.Nevertheless,the underlying deformation mechanisms(e.g.,slip versus twinning)at each deformation stage during tension and compression have not been fully understood.In this study,we employed tensile and compressive tests on extruded Al and Mn containing Mg alloy,i.e.,an AM alloy Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca,during the synchrotron X-ray diffraction.Our results show that distinct deformation behaviors and mechanisms in tension and compression are associated with the strong texture in the extruded samples:(i)The tensile deformation is dominated by dislocation slips,with activation of non-basaland<c+a>slip,but deformation twinning is suppressed.(ii)The compressive deformation shows early-stage tensile twinning,followed by dislocation slips.Twinning induces grain reorientation,leading to significant lattice strain evolution aligned with the texture.The pronounced tension-compression asymmetry is attributed to the favorable shear stress direction formed in the twinning system during compression,which facilitates the activation of tensile twins.During tension,the strain hardening rate(SHR)drops significantly after yielding due to limited activated slip systems.In contrast,the samples under compression exhibit significant increases in SHR after yielding.During compression,dislocation multiplication dominates the initial strain hardening,while twinning progressively contributes more significantly than dislocation slip at higher strains.This study improves our understanding of the tension-compression and strain hardening asymmetries in extruded AM Mg alloys.
基金the China Scholarship Council(No.201708510113)for fellowship and funding.
文摘Plasma electrolytic oxidation(PEO)processing of light metals has been established for decades and is in increasing industrial use,even as an alternative surface treatment to produce multifunctional coatings with environmental-friendly processing concept.One of the benefits of PEO processing claimed already a couple of years ago was the ability to treat dissimilar metal joints,which can obviously improve the surface homogeneity and stability at the interface of the dissimilar components,especially impeding the galvanic corrosion due to the different electrochemical properties of each component.However,the progress and breakthrough develop slowly especially for the macro scales due to the much larger gap between each component.This literature review firstly demonstrates the still low number of studies reporting successful PEO treatment of material combination such as Mg/Al,Mg/Ti,Al/Ti and scarcely light metal combinations with steel.The main issues and challenges to performing PEO processing on the macroscale dissimilar weldments were stated.On the other hand,dissimilar metal joints also widely exist in micrometer scale in alloys and metal matrix composites(MMCs).Moreover,there is a huge knowledge base on PEO treatment of such multiphase substrates.PEO processing of such complicated mixed microstructures is reviewed as well to reveal the basic problems.To some certain degree,these PEO-related studies on alloys and MMCs can be good examples to have an insight into the coating formation mechanism on macro-scaled dissimilar metal joints.Conclusions are drawn from the micro-to macroscale.Finally,critical access to the problems is given and possible solutions and reaming limitations are discussed.
基金the financial support from National Natural Science Foundation of China(No.52071067)Mobility Programme of the Sino-German Center(M-0056)+3 种基金Shenyang Young and Middle-aged Science and Technology Innovation Talent Support Program(RC231178)Natural Science Foundation Project of Liaoning Province(2022-YGJC-16)the Fundamental Research Funds for the Central Universities(N2302019)Qianqian Chen would like to acknowledge China Scholarship Council for the award of fellowship(NO.202206080011).
文摘In-situ growth of layered double hydroxide(LDH)has been considered a feasible method to further improve the corrosion protection of PEO coated Mg alloys,but the process is basically carried out in an autoclave.In this study,LDH was in-situ synthesized on PEO treated AM50 Mg by hydrothermal treatment at ambient pressure in the presence of chelating agents.Results indicated that the synergistic effect of sulfosalicylic acid(SSA)and ethylenediaminetetraacetic acid tetrasodium salt(EDTA)chelating agents is appropriate for Mg-Al LDH formation due to the sufficient quantity of highly stable Mg and Al complexes in the treatment bath.An appropriate hydrothermal treatment time was also revealed in this work,which can efficiently seal the pores and defects of PEO coating with a uniform LDH film.As a result,the corrosion protection of the coating was improved dramatically.The prolonged hydrothermal treatment is detrimental to the integrity of PEO layers.The influence of chelating agents on the LDH formation processes is supported by thermodynamic calculation of the equilibrium composition,and the formation mechanism of LDH film is discussed in depth.
基金support from the Alexander von Humboldt foundationsupport from the National Natural Science Foundation of China(No.22473077)+2 种基金support from the BENCh graduate school,funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)389479699/GRK2455support from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme grant agreement No.[833404]support from CRC 1633 Proton Coupled Electron Transfer,Project C02。
文摘Heterogeneous catalysis on solid surfaces provides high-value chemicals and is involved in a large fraction of the world’s economic productivity,yet our understanding of this important class of processes remains limited.Thermal reaction rates obtained from experiments on mod-el catalysts provide quantitative data that can reveal reaction mechanisms and provide benchmarks for computational simulations of catalytic processes.This perspective describes a critical advance in measuring these rates:velocity resolved kinetics(VRK).VRK delivers ab-solute rates for elementary surface reactions that are of sufficient accuracy that they may be meaningfully compared to theoretical rate predictions,creating a powerful synergy between theory and experiment.It is now routinely possible to derive fundamental thermochemical quantities,including desorption and adsorption energies,reaction barrier heights,diffusion barrier heights,and lateral adsorbate interaction energies.Reaction mechanisms can also be revealed and reaction intermediates directly detected.The high time resolution of VRK al-lows study of catalytic reactions at the high temperatures typical of conditions present in real catalytic reactors.Current work exploiting the newest and by far the most powerful variant of VRK has only scratched the surface of what is possible,signifying a promising future for re-searchers in this field.
