How can I change a color photo into a black-and-white picture? Irfanview.com (www.irfanview.com) is a free program you can use to convert your color photo to black and white. Once installed ...

In particular, upconversion nanoparticles that can emit all three primary colors of light-red (R), green (G), and blue (B)-from a single nanoparticle are required, but existing materials either ...