Effect of Dispersive Reflectivity on the Stability of Gap Solitons in Dual-core Bragg Gratings with Cubic-quintic Nonlinearity Topics: Nonlinear Optics and Photonics In Proceedings of the 7th International Conference on Photonics, Optics and Laser Technology PHOTOPTICS - Volume 1, 19-23, 2019 , Prague, Czech Republic