Mechanism of Excited State Double Proton Transfer in 2-Amino-3-Methoxypyridine and Acetic Acid Complex

The excited-state double-proton transfer （ESDPT） mechanism of 2-amino-3-methoxypyridine and acetic acid com- plex is studied by the density functional theory （DFT） and time-dependent DFT with CAM-B3LYP functional. The complex is connected through two different types of inter-molecular hydrogen bonds. After photo-excitation, both hydrogen bonds get strengthened, which can facilitate the ESDPT reaction. The scanned potential energy curve along the proton transfer coordinate indicates that the ESDPT reaction proceeds in a stepwise pattern.

Dependence of charge trapping of fluorescent and phosphorescent dopants in organic light-emitting diodes on the dye species and current density

This paper utilizes multilayer organic light-emitting diodes with a thin layer of dye molecules to study the mech- anism of charge trapping under different electric regimes. It demonstrates that the carrier trapping was independent of the current density in devices using fluorescent material as the emitting molecule while this process was exactly opposite when phosphorescent material was used. The triplet-triplet annihilation and dissociation of excitons into free charge carriers was considered to contribute to the decrease in phosphorescent emission under high electric fields. Moreover, the fluorescent dye molecule with a lower energy gap and ionized potential than the host emitter was observed to facilitate the carrier trapping mechanism, and it would produce photon emission.

REGULARITY OF VIBRATION RESPONSE OF MECHANICAL SYSTEM UNDER AFFECT OF VARI-FREQUENCY EXCITING FORCE

The vibration response formulas of the mechanical system under the affect of thevari-frequency exciting force are deduced. It is proved by the theoretical analysis and experimentalresults that the vibration response amplitude of the mechanical system under the affect of thevari-frequency exciting force is far smaller than that under the affect of the constant frequency exciting force on condition that the exciting force amplitudes are just the same;while the vari-fre-quency rate a increases to 5 Hz per second the vibration amplitude will decrease to 10% only as lowas that under the affect of the constant frequency exciting force. All these conclusions will be of significance for revealing the mechanism of suppressing chatter in van-speed cutting and analyzing theexperimental results of sine-wave scanning exciting test.

Observation of mode-like features in tunneling spectra of iron-based superconductors

We report scanning tunneling microscopy/spectroscopy（STM/STS） studies on iron-based superconductors of Ba1-xKxFe2As2 and nearly optimally doped Fe（Te,Se）. Mode-like features were observed universally outside the superconducting gaps in the tunneling spectra, which are similar to our previous observations in other samples and can be ascribed to the interaction between electrons and spin excitations. Furthermore, an almost linear relationship between the superconducting gaps and the superconducting transition temperatures was noted and should also be taken into account in understanding the mechanism of iron-based superconductors.

Active vibration control of piezoelectric bonded smart structures using PID algorithm

Thin-walled structures are sensitive to vibrate under even very small disturbances. In order to design a suitable controller for vibration suppression of thin-walled smart structures, an electro-mechanically coupled finite element（FE） model of smart structures is developed based on first-order shear deformation（FOSD） hypothesis. Considering the vibrations generated by various disturbances, which include free and forced vibrations, a PID control is implemented to damp both the free and forced vibrations. Additionally, an LQR optimal control is applied for comparison.The implemented control strategies are validated by a piezoelectric layered smart plate under various excitations.