Bound States in the Continuum in double layer structures.

We have theoretically investigated the reflectivity spectrums of single- and double-layer photonic crystal slabs and the dielectric multilayer stack. It is shown that light can be perfectly confined in a single-layer photonic crystal slab at a given incident angle by changing the thickness, permittivity or hole radius of the structure. With a tunable double-layer photonic crystal slab, we demonstrate that the occurrence of tunable bound states in the continuum is dependent on the spacing between two slabs.

Bis[4-amino-3,5-bis-(pyridin-2-yl)-4H-1,2,4-triazole-κ(2)N(1),N(5)]diaqua-cobalt(II) bis-(perchlorate).

In the title structure, [Co(C(12)H(10)N(6))(2)(H(2)O)(2)](ClO(4))(2), the Co(II) atom lies on an inversion centre and is coordinated in a slightly distorted octa-hedral geometry by four N atoms from two 4-amino-3,5-bis-(pyridin-2-yl)-4H-1,2,4-triazole (adpt) ligands in equatorial positions and two O atoms from two water mol-ecules in axial positions. An intra-molecular N-H⋯N inter-action stabilizes the mol-ecular conformation. Inter-molecular N-H⋯O and O-H⋯O inter-actions involving the perchlorate counter-anions extend the monomeric compound into a two-dimensional network parallel to the bc plane.

Polymerlike statistical characterization of two-dimensional granular chains.

Statistical behaviors of packing collections of granular chains in a two-dimensional container have been investigated experimentally. On compaction from their own gravity, the longer chains pack into a structure with lower packing density due to the prevalence of backbone loops. The packing of chains can be considered as the jamming of the granular system.