Structural Synthesis of a Class of 2R2T Hybrid Mechanisms

Conventional overconstrained parallel manipulators have been widely studied both in industry and academia,however the structural synthesis of hybrid mechanisms with additional constraints is seldom studied,especially for the four degrees of freedom（DOF） hybrid mechanisms.In order to develop a manipulator with additional constraints,a class of important spatial mechanisms with coupling chains（CCs） whose motion type is two rotations and two translations（2R2T） is presented.Based on screw theory,the combination of different types of limbs which are used to construct parallel mechanisms and coupling chains is proposed.The basic types of the general parallel mechanisms and geometric conditions of the kinematic chains are given using constraint synthesis method.Moreover,the 2R2T motion pattern hybrid mechanisms which are derived by adding coupling chains between different serial kinematic chains（SKCs） of the corresponding parallel mechanisms are presented.According to the constraint analysis of the mechanisms,the movement relationship of the moving platform and the kinematic chains is derived by disassembling the coupling chains.At last,fourteen novel hybrid mechanisms with two or three serial kinematic chains are presented.The proposed novel hybrid mechanisms and construction method enrich the family of the spatial mechanisms and provide an instruction to design more complex hybrid mechanisms.

Structure and Optical Property of a New 1D Iodoplumbate Hybrid Directed by in situ Synthesized Asymmetrical N-benzyl-1,4-diazabicyclo[2.2.2]octane

Simple solvothermal reaction of PbI2,1,4-diazabicyclo[2.2.2]octane and benzyl alcohol in the presence of HI acid creates a new organically templated iodoplumbate hybrid：[（N-Bz-DABCO）（PbI3）]n（1,N-Bz-DABCO＋ = N-benzyl-1,4-diazabicyclo[2.2.2]octane）.Compound 1 crystallizes in orthorhombic space group P212121 with a = 20.044（9）,b = 8.002（3）,c = 12.345（5） ？,V = 1980.1（14） A3,Z = 4,C（13）H（19）N2PbI3,Mr = 791.19,Dc = 2.654 g/cm^3,F（000） = 1408,μ（Mo Kα） = 13.189 mm–1,the final R = 0.0303 and w R = 0.0849 for 3777 observed reflections（I 〉 2σ（I））.Compound 1 contains one-dimensional anionic [PbI3]nn-chains that are enclosed into the cationic channel formed from the N-benzyl-1,4-diazabicyclo[2.2.2]octane.Noteworthy,compared with common symmetrical N,N？-dialkyl-DABCO^（2＋） cations,in-situ formed asymmetrical N-monoalkyl-DABCO~＋ cation is first used as structure directing agents/templating agents in the haloplumbate system,finally leading to the occurrence of noncentrosymmetric feature in compound 1.In addition,UV-Vis absorption spectrum analysis reveals that compound 1 is a potential semiconductor material with energy gap of 2.80 eV.

Encapsulation of superparamagnetic Fe_3O_4@SiO_2 core/shell nanoparticles in MnO_2 microflowers with high surface areas

Microflowers made of interconnected MnO2 nanosheets have been successfully synthesized in a microwave reactor through a hydrothermal reduction of KMnO4 with aqueous HCI at elevated temperatures in the presence of superparamagnetic Fe3O4SiO2 core-shell nanoparticles.Due to the chemical compatibility between SiO2 and MnO2,the heterogeneous reaction leads to the spontaneous encapsulation of the Fe3O4@SiO2 core-shell nanoparticles in the MnO2 microflowers.The resulting hybrid particles exhibit multiple properties including high surface area associated with the MnO2nanosheets and superparamagnetism originated from the Fe3O4@SiO2 core-shell nanoparticles.which are beneficial for applications requiring both high surface area and magnetic separation.