The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human–robot interaction.This compliance reduces the risk of damage to the manipulated object and its surroun...The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human–robot interaction.This compliance reduces the risk of damage to the manipulated object and its surroundings.However,continuum robots possess theoretically infinite degrees of freedom,and this high flexibility usually leads to complex deformations when subjected to external forces and positional constraints.Describing these complex deformations is the main challenge in modeling continuum robots.In this study,we investigated a novel variable curvature modeling method for continuum robots,considering external forces and positional constraints.The robot configuration curve is described using the developed mechanical model,and then the robot is fitted to the curve.A ten-section continuum robot prototype with a length of 1 m was developed in order to validate the model.The feasibility and accuracy of the model were verified by the ability of the robot to reach target points and track complex trajectories with a load.This work was able to serve as a new perspective for the design analysis and motion control of continuum robots.展开更多
Post-translational modifications of cellular proteins with ubiquitin or ubiquitin-like proteins regulate many cellular processes,such as cell proliferation,differentiation,apoptosis, signal transduction,intercellular ...Post-translational modifications of cellular proteins with ubiquitin or ubiquitin-like proteins regulate many cellular processes,such as cell proliferation,differentiation,apoptosis, signal transduction,intercellular immune recognition,inflammatory response,stress response,and DNA repair.Nice4/UBAP2L is an important member in the family of ubiquitin-like proteins,and its biological function remains unknown.This study aimed to investigate the effect of UBAP2L on spinal cord injury (SCI).At first,rat bone marrow mesenchymal stem cells (BMSCs)were infected with adeno-associated virus to induce over-expression of Nice4.Subsequently,the infected BMSCs were transplanted into rats suffering from semi-sectioned SCI.The results showed that the over-expression of Nice4 significantly promoted the proliferation and differentiation of BMSCs. In addition,the transplantation of infected BMSCs into the injured area of SCI rats improved the function repair of SCI.Importantly,the immunohistochemical and hematoxylin-eosin staining and RT-PCR results showed that the number of neuronal cells,oligodendrocytes,and astrocytes was significantly increased in the injured area,along with significantly upregulated expression ofcyclin D1 and p38 mitogen-activated protein kinase (MAPK).Meanwhile,the expression of caspase 3 protein was significantly down-regulated.In conclusion,the over-expression of Nice4 gene can promote the functional recovery in SCI rats by promoting cell proliferation and inhibiting apoptosis. The results of this study indicate an alternative option for the clinical treatment of SCI.展开更多
The independently designed and manufactured ultra-high-strength aluminum alloy Al-12.18 Zn-3.31 Mg-1.43 Cu-0.20 Zr-0.04 Sr was investigated via scanning electron microscopy observations, X-ray diffraction analysis, ha...The independently designed and manufactured ultra-high-strength aluminum alloy Al-12.18 Zn-3.31 Mg-1.43 Cu-0.20 Zr-0.04 Sr was investigated via scanning electron microscopy observations, X-ray diffraction analysis, hardness tests, electrical conductivity tests, tensile tests, intergranular corrosion tests, and exfoliation corrosion tests. The effect of pre-recovery on the microstructure and mechanical properties of this aluminum alloy was also studied. The results show that the pre-recovery heat treatment releases deformation energy, inhibits recrystallization, and decreases the dislocation density. Although the pre-recovery heat treatment has little effect on the hardness, electrical conductivity, and elongation of this aluminum alloy, it can dramatically improve the alloy's tensile strength(the maximum tensile strength increased from 785.0 MPa to 809.2 MPa). Moreover, the tensile properties of this aluminum alloy have a certain degree of isotropy, and the pre-recovery heat treatment does not affect this property. In addition, the rolled aluminum alloy exhibits good corrosion resistance, but the effect of the pre-recovery heat treatment on the alloy's resistance to intergranular and exfoliation corrosion is negligible.展开更多
The effects of various factors on the electrocarboxylation of organic compounds with carbon dioxide catalyzed by metalloporphyrin are studied.The optimal potential of electrocar- boxylation is -1.6 V(vs.SCE).A weak pr...The effects of various factors on the electrocarboxylation of organic compounds with carbon dioxide catalyzed by metalloporphyrin are studied.The optimal potential of electrocar- boxylation is -1.6 V(vs.SCE).A weak protic solvent methanol can enhance catalytic activity. Tetrabutylammonium iodide is the best one of five electrolytes.The yields and current efficiencies of electrocarboxylation are increased slowly as the concentration of catalyst increases.展开更多
By using holomorphic Riemannian geometry in C^3, the coupled Landau-Lifshitz(CLL) equation is proved to be exactly the equation of Schr¨odinger flows from R^1 to the complex 2-sphere CS^2(1) → C^3.Furthermore, r...By using holomorphic Riemannian geometry in C^3, the coupled Landau-Lifshitz(CLL) equation is proved to be exactly the equation of Schr¨odinger flows from R^1 to the complex 2-sphere CS^2(1) → C^3.Furthermore, regarded as a model of moving complex curves in C^3, the CLL equation is shown to preserve the PT symmetry if the initial data is of the P symmetry. As a consequence, the nonlocal nonlinear Schrodinger(NNLS)equation proposed recently by Ablowitz and Musslimani is proved to be gauge equivalent to the CLL equation with initial data being restricted by the P symmetry. This gives an accurate characterization of the gaugeequivalent magnetic structure of the NNLS equation described roughly by Gadzhimuradov and Agalarov(2016).展开更多
It is well-known that the general Manakov system is a 2-components nonlinear Schrodinger equation with 4 nonzero real parameters.The analytic property of the general Manakov system has been well-understood though it l...It is well-known that the general Manakov system is a 2-components nonlinear Schrodinger equation with 4 nonzero real parameters.The analytic property of the general Manakov system has been well-understood though it looks complicated.This paper devotes to exploring geometric properties of this system via the prescribed curvature representation in the category of Yang-Mills’theory.Three models of moving curves evolving in the symmetric Lie algebras u(2,1)=k_(α)⊕m_(α)(α=1,2)and u(3)=k_(3)⊕m_(3)are shown to be simultaneously the geometric realization of the general Manakov system.This reflects a new phenomenon in geometric realization of a partial differential equation/system.展开更多
Direct laser writing(DLW)has been shown to render 3D polymeric optical components,including lenses,beam expanders,and mirrors,with submicrometer precision.However,these printed structures are limited to the refractive...Direct laser writing(DLW)has been shown to render 3D polymeric optical components,including lenses,beam expanders,and mirrors,with submicrometer precision.However,these printed structures are limited to the refractive index and dispersive properties of the photopolymer.Here,we present the subsurface controllable refractive index via beam exposure(SCRIBE)method,a lithographic approach that enables the tuning of the refractive index over a range of greater than 0.3 by performing DLW inside photoresist-filled nanoporous silicon and silica scaffolds.Adjusting the laser exposure during printing enables 3D submicron control of the polymer infilling and thus the refractive index and chromatic dispersion.Combining SCRIBE’s unprecedented index range and 3D writing accuracy has realized the world’s smallest(15μm diameter)spherical Luneburg lens operating at visible wavelengths.SCRIBE’s ability to tune the chromatic dispersion alongside the refractive index was leveraged to render achromatic doublets in a single printing step,eliminating the need for multiple photoresins and writing sequences.SCRIBE also has the potential to form multicomponent optics by cascading optical elements within a scaffold.As a demonstration,stacked focusing structures that generate photonic nanojets were fabricated inside porous silicon.Finally,an all-pass ring resonator was coupled to a subsurface 3D waveguide.The measured quality factor of 4600 at 1550 nm suggests the possibility of compact photonic systems with optical interconnects that traverse multiple planes.SCRIBE is uniquely suited for constructing such photonic integrated circuits due to its ability to integrate multiple optical components,including lenses and waveguides,without additional printed supports.展开更多
In this article,we devote to a mathematical survey on the theory of the vortex filament in 3-dimensional spaces and its generalizations.We shall present some effective geometric tools applied in the study,such as the ...In this article,we devote to a mathematical survey on the theory of the vortex filament in 3-dimensional spaces and its generalizations.We shall present some effective geometric tools applied in the study,such as the Schrodinger flow,the geometric Korteweg-de Vries(KdV)flow and the generalized bi-Schrodinger flow,as well as the complex and para-complex structures.It should be mentioned that the investigation in the imaginary part of the octonions looks very fascinating,since it relates to almost complex structures and the G2 structure on S^(6).As a new result in this survey,we describe the equation of generalized bi-Schr?dinger flows from R1 into a Riemannian surface.展开更多
This paper studies serial correlation testing for a general three-dimensional panel data model. As a step for hypothesis testing, the robust within estimation of parameter coefficients is investigated, and shown to as...This paper studies serial correlation testing for a general three-dimensional panel data model. As a step for hypothesis testing, the robust within estimation of parameter coefficients is investigated, and shown to asymptotically consistent and normal under some mild conditions. A residual-based statistic is then constructed to test for serial correlation in the idiosyncratic errors, which is based on the parameter estimates for an artificial autoregression modeled by centering and differencing residuals. The test can be shown to asymptotically chisquare distributed under the null hypothesis. Power study shows that the test can detect local alternatives distinct at the parametric rate from the null hypothesis. The test needs no distribution assumptions of the error components, and is robust to the misspecification of various specific effects. Monte Carlo simulations are carried out for illustration.展开更多
A complete manifold is said to be nonparabolic if it does admit a positive Green’s function. To find a sharp geometric criterion for the parabolicity/nonparbolicity is an attractive question inside the function theor...A complete manifold is said to be nonparabolic if it does admit a positive Green’s function. To find a sharp geometric criterion for the parabolicity/nonparbolicity is an attractive question inside the function theory on Riemannian manifolds. This paper devotes to proving a criterion for nonparabolicity of a complete manifold weakened by the Ricci curvature. For this purpose, we shall apply the new Laplacian comparison theorem established by the first author to show the existence of a non-constant bounded subharmonic function.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51975566,61821005,U1908214)Key Research Program of Frontier Sciences,CAS,China(Grant No.ZDBS-LY-JSC011).
文摘The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human–robot interaction.This compliance reduces the risk of damage to the manipulated object and its surroundings.However,continuum robots possess theoretically infinite degrees of freedom,and this high flexibility usually leads to complex deformations when subjected to external forces and positional constraints.Describing these complex deformations is the main challenge in modeling continuum robots.In this study,we investigated a novel variable curvature modeling method for continuum robots,considering external forces and positional constraints.The robot configuration curve is described using the developed mechanical model,and then the robot is fitted to the curve.A ten-section continuum robot prototype with a length of 1 m was developed in order to validate the model.The feasibility and accuracy of the model were verified by the ability of the robot to reach target points and track complex trajectories with a load.This work was able to serve as a new perspective for the design analysis and motion control of continuum robots.
基金the National Natural Science Foundation of China(No.81271347).
文摘Post-translational modifications of cellular proteins with ubiquitin or ubiquitin-like proteins regulate many cellular processes,such as cell proliferation,differentiation,apoptosis, signal transduction,intercellular immune recognition,inflammatory response,stress response,and DNA repair.Nice4/UBAP2L is an important member in the family of ubiquitin-like proteins,and its biological function remains unknown.This study aimed to investigate the effect of UBAP2L on spinal cord injury (SCI).At first,rat bone marrow mesenchymal stem cells (BMSCs)were infected with adeno-associated virus to induce over-expression of Nice4.Subsequently,the infected BMSCs were transplanted into rats suffering from semi-sectioned SCI.The results showed that the over-expression of Nice4 significantly promoted the proliferation and differentiation of BMSCs. In addition,the transplantation of infected BMSCs into the injured area of SCI rats improved the function repair of SCI.Importantly,the immunohistochemical and hematoxylin-eosin staining and RT-PCR results showed that the number of neuronal cells,oligodendrocytes,and astrocytes was significantly increased in the injured area,along with significantly upregulated expression ofcyclin D1 and p38 mitogen-activated protein kinase (MAPK).Meanwhile,the expression of caspase 3 protein was significantly down-regulated.In conclusion,the over-expression of Nice4 gene can promote the functional recovery in SCI rats by promoting cell proliferation and inhibiting apoptosis. The results of this study indicate an alternative option for the clinical treatment of SCI.
基金financially supported by the Jiangsu Provincial Industrial Science and Technology Support Program (No. BE2008118)the Basic Research on Isotropic Ultra-high Strength Aluminum Matrix Composite (No. 6140922010201)
文摘The independently designed and manufactured ultra-high-strength aluminum alloy Al-12.18 Zn-3.31 Mg-1.43 Cu-0.20 Zr-0.04 Sr was investigated via scanning electron microscopy observations, X-ray diffraction analysis, hardness tests, electrical conductivity tests, tensile tests, intergranular corrosion tests, and exfoliation corrosion tests. The effect of pre-recovery on the microstructure and mechanical properties of this aluminum alloy was also studied. The results show that the pre-recovery heat treatment releases deformation energy, inhibits recrystallization, and decreases the dislocation density. Although the pre-recovery heat treatment has little effect on the hardness, electrical conductivity, and elongation of this aluminum alloy, it can dramatically improve the alloy's tensile strength(the maximum tensile strength increased from 785.0 MPa to 809.2 MPa). Moreover, the tensile properties of this aluminum alloy have a certain degree of isotropy, and the pre-recovery heat treatment does not affect this property. In addition, the rolled aluminum alloy exhibits good corrosion resistance, but the effect of the pre-recovery heat treatment on the alloy's resistance to intergranular and exfoliation corrosion is negligible.
文摘The effects of various factors on the electrocarboxylation of organic compounds with carbon dioxide catalyzed by metalloporphyrin are studied.The optimal potential of electrocar- boxylation is -1.6 V(vs.SCE).A weak protic solvent methanol can enhance catalytic activity. Tetrabutylammonium iodide is the best one of five electrolytes.The yields and current efficiencies of electrocarboxylation are increased slowly as the concentration of catalyst increases.
基金supported by National Natural Science Foundation of China(Grant No.11271073)。
文摘By using holomorphic Riemannian geometry in C^3, the coupled Landau-Lifshitz(CLL) equation is proved to be exactly the equation of Schr¨odinger flows from R^1 to the complex 2-sphere CS^2(1) → C^3.Furthermore, regarded as a model of moving complex curves in C^3, the CLL equation is shown to preserve the PT symmetry if the initial data is of the P symmetry. As a consequence, the nonlocal nonlinear Schrodinger(NNLS)equation proposed recently by Ablowitz and Musslimani is proved to be gauge equivalent to the CLL equation with initial data being restricted by the P symmetry. This gives an accurate characterization of the gaugeequivalent magnetic structure of the NNLS equation described roughly by Gadzhimuradov and Agalarov(2016).
基金supported by the National Natural Science Foundation of China(Nos.12071080,12141104)the Science Technology Project of Jiangxi Educational Committee(No.GJJ2201202)the Natural Science Foundation of Jiangxi Province(Nos.20212BAB211005,20232BAB201006)。
文摘It is well-known that the general Manakov system is a 2-components nonlinear Schrodinger equation with 4 nonzero real parameters.The analytic property of the general Manakov system has been well-understood though it looks complicated.This paper devotes to exploring geometric properties of this system via the prescribed curvature representation in the category of Yang-Mills’theory.Three models of moving curves evolving in the symmetric Lie algebras u(2,1)=k_(α)⊕m_(α)(α=1,2)and u(3)=k_(3)⊕m_(3)are shown to be simultaneously the geometric realization of the general Manakov system.This reflects a new phenomenon in geometric realization of a partial differential equation/system.
基金funded by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Award Number DE-SC0019140(Brongersma and Braun group focal characterization collaboration)the University of Illinois at Urbana-Champaign College of Engineering Strategic Research Initiative(proof-of-concept studies)the National Science Foundation(ECCS-1935289)(Goddard group,and Braun group laser patterning).
文摘Direct laser writing(DLW)has been shown to render 3D polymeric optical components,including lenses,beam expanders,and mirrors,with submicrometer precision.However,these printed structures are limited to the refractive index and dispersive properties of the photopolymer.Here,we present the subsurface controllable refractive index via beam exposure(SCRIBE)method,a lithographic approach that enables the tuning of the refractive index over a range of greater than 0.3 by performing DLW inside photoresist-filled nanoporous silicon and silica scaffolds.Adjusting the laser exposure during printing enables 3D submicron control of the polymer infilling and thus the refractive index and chromatic dispersion.Combining SCRIBE’s unprecedented index range and 3D writing accuracy has realized the world’s smallest(15μm diameter)spherical Luneburg lens operating at visible wavelengths.SCRIBE’s ability to tune the chromatic dispersion alongside the refractive index was leveraged to render achromatic doublets in a single printing step,eliminating the need for multiple photoresins and writing sequences.SCRIBE also has the potential to form multicomponent optics by cascading optical elements within a scaffold.As a demonstration,stacked focusing structures that generate photonic nanojets were fabricated inside porous silicon.Finally,an all-pass ring resonator was coupled to a subsurface 3D waveguide.The measured quality factor of 4600 at 1550 nm suggests the possibility of compact photonic systems with optical interconnects that traverse multiple planes.SCRIBE is uniquely suited for constructing such photonic integrated circuits due to its ability to integrate multiple optical components,including lenses and waveguides,without additional printed supports.
基金The first author was supported by National Natural Science Foundation of China(Grant Nos.11531012,11926307 and 12071080).
文摘In this article,we devote to a mathematical survey on the theory of the vortex filament in 3-dimensional spaces and its generalizations.We shall present some effective geometric tools applied in the study,such as the Schrodinger flow,the geometric Korteweg-de Vries(KdV)flow and the generalized bi-Schrodinger flow,as well as the complex and para-complex structures.It should be mentioned that the investigation in the imaginary part of the octonions looks very fascinating,since it relates to almost complex structures and the G2 structure on S^(6).As a new result in this survey,we describe the equation of generalized bi-Schr?dinger flows from R1 into a Riemannian surface.
基金Supported by the National Natural Science Foundation of China(No.11671263)
文摘This paper studies serial correlation testing for a general three-dimensional panel data model. As a step for hypothesis testing, the robust within estimation of parameter coefficients is investigated, and shown to asymptotically consistent and normal under some mild conditions. A residual-based statistic is then constructed to test for serial correlation in the idiosyncratic errors, which is based on the parameter estimates for an artificial autoregression modeled by centering and differencing residuals. The test can be shown to asymptotically chisquare distributed under the null hypothesis. Power study shows that the test can detect local alternatives distinct at the parametric rate from the null hypothesis. The test needs no distribution assumptions of the error components, and is robust to the misspecification of various specific effects. Monte Carlo simulations are carried out for illustration.
基金supported by the National Natural Science Foundation of China(Nos.12071080,12141104)。
文摘A complete manifold is said to be nonparabolic if it does admit a positive Green’s function. To find a sharp geometric criterion for the parabolicity/nonparbolicity is an attractive question inside the function theory on Riemannian manifolds. This paper devotes to proving a criterion for nonparabolicity of a complete manifold weakened by the Ricci curvature. For this purpose, we shall apply the new Laplacian comparison theorem established by the first author to show the existence of a non-constant bounded subharmonic function.
