The crystallization of L-sodium glutamine from its aqueous solution is studied experimentally. It is found that under certain conditions, the crystallization may exhibit periodical patterns. The effects of the tempera...The crystallization of L-sodium glutamine from its aqueous solution is studied experimentally. It is found that under certain conditions, the crystallization may exhibit periodical patterns. The effects of the temperature of crystallization, the concentration of solution (the amount of solute) and the opening of the container on the crystallization patterns are studied in some detail.展开更多
A new method based on UV photosensitivity is proposed to fabricate big scale two dimensional photonic crystal.The optical transmission properties of designed periodic structure are investigated by numerical analysis.T...A new method based on UV photosensitivity is proposed to fabricate big scale two dimensional photonic crystal.The optical transmission properties of designed periodic structure are investigated by numerical analysis.The results show that the 2D photonic crystal fabricated by the new method has a desirable photonic bandgap of TE mode.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
It has been widely accepted that spherical per- iodicity generally dominates liquid and amorphous structure formation, where atoms tend to gather near spherically peri- odic shells according to Friedel oscillation. He...It has been widely accepted that spherical per- iodicity generally dominates liquid and amorphous structure formation, where atoms tend to gather near spherically peri- odic shells according to Friedel oscillation. Here it is revealed that the same order is just hidden in the atomic global packing modes of the crystalline phases relevant to bulk metallic glasses. Among the multiple nearest-neighbor dusters devel- oped from all the non-equivalent atomic sites in a given phase, there always exists a principal duster, centered by which the spherical periodicity, both topologically and chemically, is the most distinct. Then the principal dusters plus specific glue atoms just constitute the cluster-plus-glue-atom structural units shared by both metallic glasses and the corresponding crystalline phases. It is further pointed out that the spherical periodicity order represents the common structural homology of crystalline and amorphous states in the medium-range through scrutinizing all binary bulk-glass-relevant phases in Cu-（Zr, Hf）, Ni-（Nb, Ta）, Al-Ca, and Pd-Si systems.展开更多
文摘The crystallization of L-sodium glutamine from its aqueous solution is studied experimentally. It is found that under certain conditions, the crystallization may exhibit periodical patterns. The effects of the temperature of crystallization, the concentration of solution (the amount of solute) and the opening of the container on the crystallization patterns are studied in some detail.
文摘A new method based on UV photosensitivity is proposed to fabricate big scale two dimensional photonic crystal.The optical transmission properties of designed periodic structure are investigated by numerical analysis.The results show that the 2D photonic crystal fabricated by the new method has a desirable photonic bandgap of TE mode.
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 Science Challenge Program (JCKY2016212A504)the National Natural Science Foundation of China(11674045)
文摘It has been widely accepted that spherical per- iodicity generally dominates liquid and amorphous structure formation, where atoms tend to gather near spherically peri- odic shells according to Friedel oscillation. Here it is revealed that the same order is just hidden in the atomic global packing modes of the crystalline phases relevant to bulk metallic glasses. Among the multiple nearest-neighbor dusters devel- oped from all the non-equivalent atomic sites in a given phase, there always exists a principal duster, centered by which the spherical periodicity, both topologically and chemically, is the most distinct. Then the principal dusters plus specific glue atoms just constitute the cluster-plus-glue-atom structural units shared by both metallic glasses and the corresponding crystalline phases. It is further pointed out that the spherical periodicity order represents the common structural homology of crystalline and amorphous states in the medium-range through scrutinizing all binary bulk-glass-relevant phases in Cu-（Zr, Hf）, Ni-（Nb, Ta）, Al-Ca, and Pd-Si systems.
