Structure and Photoluminescence Properties of Dy3+ Doped Phosphor with Whitlockite Structure.

Whitlockite has the advantages of a low sintering temperature, high stability, and a low fabrication cost, and it is widely used as the host for luminescent material. In this study, Ca1.8Li0.6La0.6-x(PO4)2:xDy3+ phosphor was prepared by the high-temperature solid-state method, and its structure, composition, and luminescence properties were systematically studied. The results showed that a new whitlockite type matrix was prepared by replacing Ca2+ in whitlockite with monovalent and trivalent cations. The prepared phosphors belonged to a hexagonal crystal system with a particle size in the range of 5-20 µm. Under the excitation of 350 nm UV light, the samples emitted white light, and there were mainly two stronger emission peaks at 481 nm in the blue band and 573 nm in the yellow band, which correspond to the electron transitions at 4F9/2→6H15/2 and 4F9/2→6H13/2 of Dy3+, respectively. The optimal doping concentration of Dy3+ in Ca1.8Li0.6La0.6(PO4)2 matrix was 0.03 (mol%). The main mechanism of concentration quenching in the sample was dipole-dipole energy transfer. When the temperature was 130 °C, the luminescence intensity of the samples was 78.7% of that at 30 °C, and their thermal quenching activation energy was 0.25 eV. The CIE coordinates of the sample at 30 °C were (0.2750, 0.3006), and their luminescent colors do not change with temperature. All the results indicate that Ca1.8Li0.6La0.6-x(PO4)2:xDy3+ phosphor is a luminescent material with good luminescence performance and thermal stability, which shows a promising application in the field of LED display.

MiRNA: a potential target for gene diagnosis and treatment of atherosclerotic stroke.

Stroke is one of the major diseases that endanger the physical health life of middle-aged and old people. It has the characteristics of high incidence, mortality and disability rate. Atherosclerosis is the main intervention target for stroke prevention and treatment. MiRNAs are highly expressed in the cerebral vasculature and play an important regulatory role in the pathogenesis of neuronal damage and ischemic stroke. This article reviews the mechanism of action between miRNAs and atherosclerosis, stroke, ischemia-reperfusion injury, collateral circulation and circRNA molecular networks, providing theoretical support for miRNA in gene diagnosis and drug therapy of atherosclerotic stroke.