RESUMEN
This study demonstrates a tunable Fresnel lens in an azo-dye-doped liquid crystal (ADDLC) film using an interference technique. One Fresnel-patterned green beam using a Sagnac interferometer irradiated the UV-illuminated ADDLC cell, yielding a concentric zone plate distribution with homeotropic and isotropic structures in bright and dark regions of the green interference pattern. The proposed Fresnel lens is polarization independent, focus tunable, and the focusing efficiency of the device can be optically controlled.
Asunto(s)
Compuestos Azo/química , Colorantes/química , Interferometría/instrumentación , Lentes , Cristales Líquidos/química , Fenómenos ÓpticosRESUMEN
Betel (areca) nuts are extensively chewed in many countries. This has been associated with respiratory symptoms. We aimed to determine whether betel nut chewing is associated with acute changes in fractional exhaled nitric oxide, a non-invasive marker of airway inflammation. Betel nut chewing resulted in an immediate significant decline in fractional exhaled nitric oxide levels that persisted for up to 180 minutes. This effect has to be taken into account in epidemiological studies, reference ranges, and patient preparation.