Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. Most emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. However, when the absorbed electromagnetic radiation is intense, it is possible for one electron to absorb two photons; this two-photon absorption can lead to emission of radiation having a shorter wavelength than the absorbed radiation. Fluorescence occurs when an orbital electron of a molecule, atom or nanostructure relaxes to its ground state by emitting a photon of light after being excited to a higher quantum state.
Burdock, also known as lesser burdock, wild rhubarb, clothbur, beggar's buttons or gypsy's rhubarb, is any of a group of biennial thistles in the genus Arctium, family Asteraceae. Native to the Old World, several species have been widely introduced worldwide. The prickly heads of these plants (burrs) are noted for easily catching on to fur and clothing, thus providing an excellent mechanism for seed dispersal. After taking his dog for a walk one day in the early 1940s, George de Mestral, a Swiss inventor, became curious about the seeds of the burdock plant that had attached themselves to his clothes and to the dog's fur. Under a microscope, he looked closely at the hook-and-loop system that the seeds use to hitchhike on passing animals aiding seed dispersal, and he realized that the same approach could be used to join other things together. The result was Velcro.
Iguana is a genus of lizard native to tropical areas of Central and South America and the Caribbean. Two species are included in the genus Iguana: the Green Iguana, which is widespread throughout its range and a popular pet, and the Lesser Antillean Iguana, which is endemic to the Lesser Antilles and endangered due to habitat destruction.
