The synthesis and characterization of PEG-like macromolecular structures on Nit inol surface from tri (ethylene glycol) dimethyl-ether under ECR-cold-plasma conditions were discussed. It was demonstrated that based o...The synthesis and characterization of PEG-like macromolecular structures on Nit inol surface from tri (ethylene glycol) dimethyl-ether under ECR-cold-plasma conditions were discussed. It was demonstrated that based on high-resolution ES CA, ATR-FTIR and contact angle investigations, the deposited PEG-like layers a re composed mainly of -CH 2-CH 2-O- linkages. These structures have a relati vely low contact angle. Compared to the unmodified surfaces, the plasma-treated Nitinol surfaces are more hydrophilic. Plasma enhanced coatings of PEG-like la yers can prevent Ni ion from releasing, thereby improving the biocompatibility o f Nitinol.展开更多
A new quaternary mixed anion complex of gadolinium(Ⅲ), [Gd(CH 3CH 2COO) 2(N O 3)(phen)] 2, was synthesized and structurally characterized. The ESR spectr um of the complex with effective g values of 5.314, 2 47...A new quaternary mixed anion complex of gadolinium(Ⅲ), [Gd(CH 3CH 2COO) 2(N O 3)(phen)] 2, was synthesized and structurally characterized. The ESR spectr um of the complex with effective g values of 5.314, 2 473 and 1.880 in poly crys talline powder at room temperature is quite different from the U spectrum. The c oordination number of Gd 3+ is nine with a monocapped square antiprism geom etry. And the stacking effect was observed in the complex. The crystal of the co mplex belongs to triclinic with space group P 1, a=0.9626(4) n m, b=0.9732(4) nm, c=1.1758(5) nm, α=102.45(1)°, β=108.16(1) °, γ=96.68(2)°, V=1.0018(7) nm3, Z=2, D c=1.80 g·cm -3 , μ(MoKα)=33.63 mm -1, F(000)=530, GOF=1.80, R=0.023 and R w=0.027.展开更多
The steady analytical solution of the perturbation equations describing the mesoscale vortex in the atmosphere is obtained. By analyzing the 3D wind field, the 3D spiral structure in physical space for unstable strati...The steady analytical solution of the perturbation equations describing the mesoscale vortex in the atmosphere is obtained. By analyzing the 3D wind field, the 3D spiral structure in physical space for unstable stratification is found. In many respects such as the 3D distribution of pressure and vorticity fields, the mesoscale spiral vortex is very similar to typically real cyclones. Key words Spirals tructure - Cyclones - 3D dynamical system Supported by the State Key Research Project on the Nonlinear Science and the Fund for Doctoral Station of the Ministry of Education, China.展开更多
Electromagnetic wave absorbing materials are urgently required in the fields of medicine,communication,and military.However,the thickness,weight,narrow effective bandwidth,and weak absorbing ability of the materials r...Electromagnetic wave absorbing materials are urgently required in the fields of medicine,communication,and military.However,the thickness,weight,narrow effective bandwidth,and weak absorbing ability of the materials restrict their further application.In this work,a double-layer hollow nanocube with a dielectric titanium dioxide(TiO_(2))shell and a magnetic CoFe oxide inner shell is prepared.Prussian blue(PB)is prepared by the hydrothermal method,and used as the template to prepare PB@CoFe PB analogue(PBA).After selective etching and further calcination,hollow CoFe oxide particles are obtained.The obtained particles are then coated with SiO_(2)and TiO_(2),respectively,and the intermediate layer is dislodged to obtain the final CoFe oxide@TiO_(2)with the hollow double shell structure.The obtained double-layer hollow structure can effectively capture the incident electromagnetic waves,and increase the propagation path.Moreover,the obvious enhancement of interface polarization and the improvement of impedance matching enhance the wave absorbing ability of the material.The analysis results show that,the structure is stable and the dispersion is good.The maximum reflection loss(RL)at 10 GHz is as high as-46.1 dB with the sample thickness of 1.6 mm.The light-weight and high-efficiency CoFe oxide@TiO_(2)absorber is promised to be used in commercial and military aerospace fields.展开更多
The growing demand for portable electronic devices means that lightweight power sources are increasingly sought after. Electric double layer capacitors （EDLCs） are promising candidates for use in lightweight power s...The growing demand for portable electronic devices means that lightweight power sources are increasingly sought after. Electric double layer capacitors （EDLCs） are promising candidates for use in lightweight power sources due to their high power densities and outstanding charge/discharge cycling stabilities. Three-dimensional （3D） self-supporting carbon-based materials have been extensively studied for use in lightweight EDLCs. Yet, a major challenge for 3D carbon electrodes is the limited ion diffusion rate in their internal spaces. To address this limitation, hierarchically porous 3D structures that provide additional channels for internal ion diffusion have been proposed. Herein, we report a new chemical method for the synthesis of an ultralight （9.92 mg/cm3） 3D porous carbon foam （PCF） involving carbonization of a glutaraldehyde- cross-linked chitosan aerogel in the presence of potassium carbonate. Electron microscopy images reveal that the carbon foam is an interconnected network of carbon sheets containing uniformly dispersed macropores. In addition, Brunauer-Emmett-Teller measurements confirm the hierarchically porous structure. Electrochemical data show that the PCF electrode can achieve an outstanding gravimetric capacitance of 246.5 F/g at a current density of 0.5 A/g, and a remarkable capacity retention of 67.5% was observed when the current density was increased from 0.5 to 100A/g. A quasi-solid-state symmetric supercapacitor was fabricated via assembly of two pieces of the new PCF and was found to deliver an ultra-high power density of 25 kW/kg at an energy density of 2.8 Wh/kg. This study demonstrates the synthesis of an ultralight and hierarchically porous carbon foam with high capacitive performance.展开更多
基金Funded by the National Natural Science Foundation of China (No.1997207150274065) and the Special Funds for Major State Basic Research Project (No.2002CB412704)
文摘The synthesis and characterization of PEG-like macromolecular structures on Nit inol surface from tri (ethylene glycol) dimethyl-ether under ECR-cold-plasma conditions were discussed. It was demonstrated that based on high-resolution ES CA, ATR-FTIR and contact angle investigations, the deposited PEG-like layers a re composed mainly of -CH 2-CH 2-O- linkages. These structures have a relati vely low contact angle. Compared to the unmodified surfaces, the plasma-treated Nitinol surfaces are more hydrophilic. Plasma enhanced coatings of PEG-like la yers can prevent Ni ion from releasing, thereby improving the biocompatibility o f Nitinol.
文摘A new quaternary mixed anion complex of gadolinium(Ⅲ), [Gd(CH 3CH 2COO) 2(N O 3)(phen)] 2, was synthesized and structurally characterized. The ESR spectr um of the complex with effective g values of 5.314, 2 473 and 1.880 in poly crys talline powder at room temperature is quite different from the U spectrum. The c oordination number of Gd 3+ is nine with a monocapped square antiprism geom etry. And the stacking effect was observed in the complex. The crystal of the co mplex belongs to triclinic with space group P 1, a=0.9626(4) n m, b=0.9732(4) nm, c=1.1758(5) nm, α=102.45(1)°, β=108.16(1) °, γ=96.68(2)°, V=1.0018(7) nm3, Z=2, D c=1.80 g·cm -3 , μ(MoKα)=33.63 mm -1, F(000)=530, GOF=1.80, R=0.023 and R w=0.027.
基金Supported by the State Key Research Project on the Nonlinear Science the Fund for Doctoral Station of the Ministry of Educat
文摘The steady analytical solution of the perturbation equations describing the mesoscale vortex in the atmosphere is obtained. By analyzing the 3D wind field, the 3D spiral structure in physical space for unstable stratification is found. In many respects such as the 3D distribution of pressure and vorticity fields, the mesoscale spiral vortex is very similar to typically real cyclones. Key words Spirals tructure - Cyclones - 3D dynamical system Supported by the State Key Research Project on the Nonlinear Science and the Fund for Doctoral Station of the Ministry of Education, China.
基金the National Natural Science Foundation of China(Nos.51773060,5207309151573045)the Shanghai Key Laboratory of Advanced Polymer Materials。
文摘Electromagnetic wave absorbing materials are urgently required in the fields of medicine,communication,and military.However,the thickness,weight,narrow effective bandwidth,and weak absorbing ability of the materials restrict their further application.In this work,a double-layer hollow nanocube with a dielectric titanium dioxide(TiO_(2))shell and a magnetic CoFe oxide inner shell is prepared.Prussian blue(PB)is prepared by the hydrothermal method,and used as the template to prepare PB@CoFe PB analogue(PBA).After selective etching and further calcination,hollow CoFe oxide particles are obtained.The obtained particles are then coated with SiO_(2)and TiO_(2),respectively,and the intermediate layer is dislodged to obtain the final CoFe oxide@TiO_(2)with the hollow double shell structure.The obtained double-layer hollow structure can effectively capture the incident electromagnetic waves,and increase the propagation path.Moreover,the obvious enhancement of interface polarization and the improvement of impedance matching enhance the wave absorbing ability of the material.The analysis results show that,the structure is stable and the dispersion is good.The maximum reflection loss(RL)at 10 GHz is as high as-46.1 dB with the sample thickness of 1.6 mm.The light-weight and high-efficiency CoFe oxide@TiO_(2)absorber is promised to be used in commercial and military aerospace fields.
基金This work was supported by Jiangsu Government Scholarship for overseas studies, National Nature Science Foundation of China （Nos. 11204266 and 21276220）, and Nature Science Foundation of Jiangsu Province （Nos. BK20141262 and BK20140463）. The authors thank Dr. Tom Yuzvinsky from University of California, Santa Cruz for SEM images acquisition and acknowledge the W. M. Keck Center for Nanoscale Opto-fluidics for use of the FEI Quanta 3D Dual-beam scanning electron microscope. The authors also acknowledge Prof. Zhonghua Zhang from Shandong University for his help with BET characterization, Prof. Jin Z. Zhang from University of California, Santa Cruz, for offering the access to Reinshaw Raman spectrometer, Mr. Fuxin Wang from Sun Yat-sen University for TEM characterization, Prof. Xiaoxia Liu and Mr. Yu Song from Northeastern University for their generous help with AFM characterization.
文摘The growing demand for portable electronic devices means that lightweight power sources are increasingly sought after. Electric double layer capacitors （EDLCs） are promising candidates for use in lightweight power sources due to their high power densities and outstanding charge/discharge cycling stabilities. Three-dimensional （3D） self-supporting carbon-based materials have been extensively studied for use in lightweight EDLCs. Yet, a major challenge for 3D carbon electrodes is the limited ion diffusion rate in their internal spaces. To address this limitation, hierarchically porous 3D structures that provide additional channels for internal ion diffusion have been proposed. Herein, we report a new chemical method for the synthesis of an ultralight （9.92 mg/cm3） 3D porous carbon foam （PCF） involving carbonization of a glutaraldehyde- cross-linked chitosan aerogel in the presence of potassium carbonate. Electron microscopy images reveal that the carbon foam is an interconnected network of carbon sheets containing uniformly dispersed macropores. In addition, Brunauer-Emmett-Teller measurements confirm the hierarchically porous structure. Electrochemical data show that the PCF electrode can achieve an outstanding gravimetric capacitance of 246.5 F/g at a current density of 0.5 A/g, and a remarkable capacity retention of 67.5% was observed when the current density was increased from 0.5 to 100A/g. A quasi-solid-state symmetric supercapacitor was fabricated via assembly of two pieces of the new PCF and was found to deliver an ultra-high power density of 25 kW/kg at an energy density of 2.8 Wh/kg. This study demonstrates the synthesis of an ultralight and hierarchically porous carbon foam with high capacitive performance.
