Configurations of Shock Regular Reflection by Straight Wedges

We are concerned with the shock regular reflection configurations of unsteady global solutions for a plane shock hitting a symmetric straight wedge.It has been known that patterns of the shock reflection are various and complicated,including the regular and the Mach reflection.Most of the fundamental issues for the shock reflection have not been understood.Recently,there are great progress on the mathematical theory of the shock regular reflection problem,especially for the global existence,uniqueness,and structural stability of solutions.In this paper,we show that there are two more possible configurations of the shock regular reflection besides known four configurations.We also give a brief proof of the global existence of solutions.

Thermally stable photoluminescence and long persistent luminescence of Ca3Ga4O9:Tb^3+/Zn^2+

A green long persistent luminescence（LPL） phosphor Ca3Ga4O9：Tb3＋/Zn2＋ was prepared. Ca3 Ga4 O9 matrix exhibits blue self-activated LPL due to the creation of intrinsic traps. When Tb3＋ is doped, the photoluminescence（PL） and LPL colors change from blue to green with their intensities significantly enhanced. The doping of Zn^（2＋） evidently improves the PL and LPL performances of the Ca3Ga4O9 matrix and Ca3Ga4O9：Tb^（3＋）. The thermoluminescence（TL） spectra show that a successive trap distribution is formed by multiple intrinsic traps with different depths in the Ca3 Ga4 O9 matrix, and the incorporation of Tb^（3＋） and Zn^（2＋） effectively increases the densities of these intrinsic traps. The existence of a successive trap distribution makes the Ca3 Ga4 O9：Tb^（3＋）/Zn^（2＋） phosphor exhibit thermally stable PL and LPL, It is indicated that this phosphor shows great promise for the application such as high-temperature LPL phosphor.

A NIR to NIR rechargeable long persistent luminescence phosphor Ca_(2)Ga_(2)GeO_(7):Yb^(3+),Tb^(3+)

Near infrared to near infrared(NIR-NIR)photo-stimulated persistent luminescence(PSPL)has shown excellent potential in high-resolution bioimaging for deep tissues.However,the PSPL in NIR-Ⅱregion(900-1700 nm)is still lacking.In this work,Ca_(2)Ga_(2)GeO_(7):Yb^(3+),Tb^(3+)(CGGYT)phosphor with unique lowdimensional crystal structure was synthesized by high-temperature solid-state reaction.Thanks to the carriers transferring from deep traps to shallow ones induced by low energy light,the 978 nm PSPL originating from ^(2)F_(5/2) to ^(2)F_(7/2) transition of Yb^(3+)induced by multimode stimulating(980 nm or WLED)is successfully realized after pre-excited by UV lamp.The NIR PSPL of the specimen can be repeatedly stimulated after placed in dark for 12 h.Moreover,the results indicate that codoping with Tb^(3+)can significantly enhance the NIR-ⅡPSPL owing to the quantum cutting persistent energy transfer(QC PET)from Tb^(3+)to Yb^(3+).Our study points to a new direction for the future development of multimode PSPL materials for bioimaging or multimode optical storage applications.