Nature and technology often adopt structures that can be described as tubular helical assemblies.However,the role and mechanisms of these structures remain elusive.In this paper,we study the mechanical response under ...Nature and technology often adopt structures that can be described as tubular helical assemblies.However,the role and mechanisms of these structures remain elusive.In this paper,we study the mechanical response under compression and extension of a tubular assembly composed of 8 helical Kirchholf rods,arranged in pairs with opposite chirality and connected by pin joints,both analytically and numerically.We first focus on compression and find that,whereas a single helical rod would buckle,the rods of the assembly deform coherently as stable helical shapes wound around a common axis.Moreover,we investigate the response of the assembly under different boundary conditions,highlighting the emergence of a central region where rods remain circular helices.Secondly,we study the effects of different hypotheses on the elastic properties of rods,i.e.,stress-free rods when straight versus when circular helices,Kirchhoff’s rod model versus Sadowsky’s ribbon model.Summing up,our findings highlight the key role of mutual interactions in generating a stable ensemble response that preserves the helical shape of the individual rods,as well as some interesting features,and they shed some light on the reasons why helical shapes in tubular assemblies are so common and persistent in nature and technology.展开更多
Chiral quantum dot(in rod)-light-emitting diodes(CQLEDs)with circularly polarized electroluminescence(CPEL)have driven interest in the future display,communication,and storage industries.However,the preparation of CQL...Chiral quantum dot(in rod)-light-emitting diodes(CQLEDs)with circularly polarized electroluminescence(CPEL)have driven interest in the future display,communication,and storage industries.However,the preparation of CQLEDs is still a challenging unresolved.Herein,we fabricated CQLEDs through spin-coating evaporation of chiral CdSe/CdS quantum rods(CCCQs)colloidal solution on indium tin oxide substrate.The CCCQs were synthesized via an isotropically epitaxial growth with cholic acid as the symmetry breaking agent,which induced one-direction chiral dislocation around the c axis of their hexagonal crystal structure.The CCCQs were ranked side-by-side in right-handed chiral arrangement with helical axis perpendicular to substrate due to chiral driving force of the cholic acid arrangement.The CQLEDs exhibited a negative CPEL signal at 600 nm with a|gEL|of 2×10^(−4),which is ascribable to the selective filtration on emission arising from the circular Bragg resonance by quasi-photonic crystal structures.展开更多
基金Open access funding provided by Scuola Superiore Sant’Anna within the CRUI-CARE Agreement.
文摘Nature and technology often adopt structures that can be described as tubular helical assemblies.However,the role and mechanisms of these structures remain elusive.In this paper,we study the mechanical response under compression and extension of a tubular assembly composed of 8 helical Kirchholf rods,arranged in pairs with opposite chirality and connected by pin joints,both analytically and numerically.We first focus on compression and find that,whereas a single helical rod would buckle,the rods of the assembly deform coherently as stable helical shapes wound around a common axis.Moreover,we investigate the response of the assembly under different boundary conditions,highlighting the emergence of a central region where rods remain circular helices.Secondly,we study the effects of different hypotheses on the elastic properties of rods,i.e.,stress-free rods when straight versus when circular helices,Kirchhoff’s rod model versus Sadowsky’s ribbon model.Summing up,our findings highlight the key role of mutual interactions in generating a stable ensemble response that preserves the helical shape of the individual rods,as well as some interesting features,and they shed some light on the reasons why helical shapes in tubular assemblies are so common and persistent in nature and technology.
基金supported by the National Natural Science Foundation of China(Nos.21931008,S.C.21922304,21873072,L.H.,and 21975184,Y.D.)+1 种基金the National Key R&D Program of China(No.2021YFA1200300,S.C.)the Science Foundation of the Shanghai Municipal Science and Technology Commission(No.19JC1410300,S.C.).
文摘Chiral quantum dot(in rod)-light-emitting diodes(CQLEDs)with circularly polarized electroluminescence(CPEL)have driven interest in the future display,communication,and storage industries.However,the preparation of CQLEDs is still a challenging unresolved.Herein,we fabricated CQLEDs through spin-coating evaporation of chiral CdSe/CdS quantum rods(CCCQs)colloidal solution on indium tin oxide substrate.The CCCQs were synthesized via an isotropically epitaxial growth with cholic acid as the symmetry breaking agent,which induced one-direction chiral dislocation around the c axis of their hexagonal crystal structure.The CCCQs were ranked side-by-side in right-handed chiral arrangement with helical axis perpendicular to substrate due to chiral driving force of the cholic acid arrangement.The CQLEDs exhibited a negative CPEL signal at 600 nm with a|gEL|of 2×10^(−4),which is ascribable to the selective filtration on emission arising from the circular Bragg resonance by quasi-photonic crystal structures.