Under a given condition of crystallization, dark brown short rhombohedron crystals could be obtained from Δ nifZ MoFe protein purified from a nifZ deleted mutant strain of Azotobacter vinelandii Lipmann....Under a given condition of crystallization, dark brown short rhombohedron crystals could be obtained from Δ nifZ MoFe protein purified from a nifZ deleted mutant strain of Azotobacter vinelandii Lipmann. Systematic studies on the effect of concentrations of PEG 8000,MgCl 2, NaCl,Tris and buffer pH on the crystallization and crystal growth of the protein showed that the protein could not be crystallized in lower concentrations of the chemicals and lower buffer pH. A large amount of smaller crystals of the protein appeared in a week with gradual increasing in the chemical concentrations and pH≥8.0. When the chemical concentrations were further increased, the time for crystallization was increased and a few high grade crystals of larger size were formed. If the concentrations of the chemicals were continuously increased, many crystals with smaller size, and, sometimes of poor quality appeared again and eventually ceased to produce any crystals. The optimal concentration for each of the above mentioned chemicals varies with other variable factors. Only one bigger crystal (both of the longest two sides: 0.16 mm) could be obtained in a hanging drop of protein sample when the concentrations of PEG 8000, MgCl 2, NaCl,Tris and protein were kept at 1.86%, 300 mmol/L, 400 mmol/L, 53 mmol/L and 4.64 g/L , respectively, with Tris buffer pH 8.2.展开更多
Band gap materials(i.e.phononic crystals) are the artificially periodic structures,which have the stop band characteristic for elastic waves.The elastic waves will be localized in phononic crystals with defects,which ...Band gap materials(i.e.phononic crystals) are the artificially periodic structures,which have the stop band characteristic for elastic waves.The elastic waves will be localized in phononic crystals with defects,which results in the energy being accumulated around the defects.As a result,it is important to analyze the wave propagation and localization in band gap materials,especially for the structures consisting of smart materials.For example,with the mechanical-electro and mechanical-electro-magneto coupling,the phononic crystals consisting of piezoelectric and magnetoelectroelastic materials can be applied widely.This sets the theoretical basis for the design of band gap materials with multi fields coupling.This paper reviews the recent development of the elastic wave propagation and localization in both ordered and disordered band gap materials.The discussion focuses on the stop band and localization characteristics of elastic waves.Analytical methods and important results are also presented.Finally,some problems for further studies are discussed.This work aims to present the basic properties of wave band gaps in phononic crystals and wave localization in disordered periodic structures(e.g.phononic crystals with definite and random defects and phononic quasicrystals).展开更多
Luminescence modification of lanthanide ions has attracted great attention due to its applications in sensing,colorful display, information transmission and anti-counterfeiting. Traditional methods of tuning fluoresce...Luminescence modification of lanthanide ions has attracted great attention due to its applications in sensing,colorful display, information transmission and anti-counterfeiting. Traditional methods of tuning fluorescence typically employ tuning compositions that are not conducive to the development of multi-environment detection and anti-counterfeiting. In this study, lanthanide ions doped ferroelectric nanocomposite was exploited with external stimuli. The upconversion luminescence modification was preformed via both the thermal and electric fields. The anti-thermal quenching phenomenon was observed in the prepared nanocomposite, which could effectively enhance the upconversion luminescence of lanthanide ions. Based on the electromechanical softness of the ferroelectric lattice, exceptional luminescence modification was realized through electric polarization. The luminescence modifications by thermal and electric fields exhibited excellent reversibility and non-volatility. These results provide unique insights into the development of integrated stimulus responsive smart devices, colorful display and advanced multi-mode sensing materials.展开更多
文摘Under a given condition of crystallization, dark brown short rhombohedron crystals could be obtained from Δ nifZ MoFe protein purified from a nifZ deleted mutant strain of Azotobacter vinelandii Lipmann. Systematic studies on the effect of concentrations of PEG 8000,MgCl 2, NaCl,Tris and buffer pH on the crystallization and crystal growth of the protein showed that the protein could not be crystallized in lower concentrations of the chemicals and lower buffer pH. A large amount of smaller crystals of the protein appeared in a week with gradual increasing in the chemical concentrations and pH≥8.0. When the chemical concentrations were further increased, the time for crystallization was increased and a few high grade crystals of larger size were formed. If the concentrations of the chemicals were continuously increased, many crystals with smaller size, and, sometimes of poor quality appeared again and eventually ceased to produce any crystals. The optimal concentration for each of the above mentioned chemicals varies with other variable factors. Only one bigger crystal (both of the longest two sides: 0.16 mm) could be obtained in a hanging drop of protein sample when the concentrations of PEG 8000, MgCl 2, NaCl,Tris and protein were kept at 1.86%, 300 mmol/L, 400 mmol/L, 53 mmol/L and 4.64 g/L , respectively, with Tris buffer pH 8.2.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11002045,11172084,10632020 and 10672017)
文摘Band gap materials(i.e.phononic crystals) are the artificially periodic structures,which have the stop band characteristic for elastic waves.The elastic waves will be localized in phononic crystals with defects,which results in the energy being accumulated around the defects.As a result,it is important to analyze the wave propagation and localization in band gap materials,especially for the structures consisting of smart materials.For example,with the mechanical-electro and mechanical-electro-magneto coupling,the phononic crystals consisting of piezoelectric and magnetoelectroelastic materials can be applied widely.This sets the theoretical basis for the design of band gap materials with multi fields coupling.This paper reviews the recent development of the elastic wave propagation and localization in both ordered and disordered band gap materials.The discussion focuses on the stop band and localization characteristics of elastic waves.Analytical methods and important results are also presented.Finally,some problems for further studies are discussed.This work aims to present the basic properties of wave band gaps in phononic crystals and wave localization in disordered periodic structures(e.g.phononic crystals with definite and random defects and phononic quasicrystals).
基金supported by the National Natural Science Foundation of China (61705214)Zhejiang Provincial Natural Science Foundation of China (LY19E020004)
文摘Luminescence modification of lanthanide ions has attracted great attention due to its applications in sensing,colorful display, information transmission and anti-counterfeiting. Traditional methods of tuning fluorescence typically employ tuning compositions that are not conducive to the development of multi-environment detection and anti-counterfeiting. In this study, lanthanide ions doped ferroelectric nanocomposite was exploited with external stimuli. The upconversion luminescence modification was preformed via both the thermal and electric fields. The anti-thermal quenching phenomenon was observed in the prepared nanocomposite, which could effectively enhance the upconversion luminescence of lanthanide ions. Based on the electromechanical softness of the ferroelectric lattice, exceptional luminescence modification was realized through electric polarization. The luminescence modifications by thermal and electric fields exhibited excellent reversibility and non-volatility. These results provide unique insights into the development of integrated stimulus responsive smart devices, colorful display and advanced multi-mode sensing materials.
