The reflectivity map is theoretically investigated by applying the transfer matrix method in a metal-dielectric mirror structure at normal incidence. The existence of multiple optical Tamm states (OTSs) is demonstrated in this structure. It is found that an OTS is periodic resonance with the variation of the top-layer thickness of the dielectric mirror for a given wavelength. The energy for the corresponding OTS mainly depends on the thickness of the top layer. The appropriate thicknesses of metal film are proposed for the convenient observation of OTSs. This work may be useful in designing a new type of multichannel filter in optical communication systems.
Glucagon-like
peptide-1 (GLP-1) secreted from enteroendocrine L-cells
is a pleiotropic hormone with beneficial potential related to islet
function, diet control, glucose homeostasis, inflammation relief,
and cardiovascular protection. The present study aimed at investigating
the effect of Polygonatum cyrtonema polysaccharide (PCP) after structural identification on GLP-1 secretion
and the possible mechanism involved in the PCP-stimulated secretion
of GLP-1. It was found that GLP-1 secretion was effectively promoted
(p < 0.01) by PCP both in rats with oral administration
for 5 weeks (13.9 ± 0.3–35.8 ± 0.3 pmol/L) and ileal
administration within 2 h (13.6 ± 0.4–34.1 ± 1.1
pmol/L) and in enteroendocrine NCI-H716 cells with direct stimulation
within 24 h (2.05 ± 0.3–20.7 ± 0.2 pmol/L). The sweet
taste receptor T1R2/T1R3 was identified to be essential for NCI-H716
cells to directly recognize PCP. The intervention experiments showed
that PCP-stimulated GLP-1 secretion was significantly depressed (p < 0.01) not only by antibodies, siRNA, and the inhibitor
of T1R2/T1R3 but also by an adenylate cyclase inhibitor. These results
suggest that PCP stimulates GLP-1 secretion from enteroendocrine cells
possibly through activation of the T1R2/T1R3-mediated cAMP signaling
pathway.
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