Today’s article

term: ultracentrifuge

a device used to separate particles of less than 100 nm size (colloids, subcellular particles, macromolecules of protein, nucleic acidslipids, polysaccharides, synthetic polymers, etc.), suspended or dissolved in the liquid. This is achieved through rotor rotation that causes centrifugal field with acceleration, which exceeds the acceleration of gravity by many orders of magnitude. ...

Today’s picture

distributed feedback laser


injection semiconductor laser, in which the feedback is produced by light waves reflection from a periodic lattice generated in the active medium.


In the injection heterolasers with distributed feedback (DFB lasers) to create a feedback one of the heterointerfaces is corrugated, which creates a periodic variation in the refractive index and leads to an interference reflection (see Fig.). The lattice period  ...