Yadong Yin [...] and his colleagues at the University of California at Riverside have invented a type of paper that can be printed on using just light, erased by heating, and reused up to 80 times.
Yin created nanoparticles, which are a million times smaller than the thickness of human hair, with the dye Prussian blue, or its chemical analogues, and titanium oxide, which is commonly used in white wall paint. This mixture is then applied to normal paper.
When the coating is exposed to ultraviolet light, electrons from titanium oxide move to the dye in the nanoparticle. This addition of electrons makes the blue dye turn white. Focusing the ultraviolet light into shapes, you can print white words on a blue background—or blue words on a white background, which are easier to read.
If left alone, the paper reverts to its original state in five days. That process can be accelerated by heating the paper to 120 °C (250 °F) for 10 minutes.
(Score: 3, Interesting) by Appalbarry on Monday February 06 2017, @12:36AM
Any time someone invents a product like this my first questions is: what does this stuff turn into once you've thrown it away?
the dye Prussian blue, or its chemical analogues, and titanium oxide
What kind of nasty does that eventually become?
(Score: 2) by MichaelDavidCrawford on Monday February 06 2017, @01:20AM
Prussian blue and sulfuric acid makes hydrogen cyanide.
I know - extremely dilute HCN smells pleasantly of almonds. I had the idea I'd surprise my sister with some homemade perfume, so I distilled some pure.
Take it from me you don't want to smell it.
Yes I Have No Bananas. [gofundme.com]
(Score: 3, Informative) by butthurt on Monday February 06 2017, @11:37AM
Prussian blue is included in the World Health Organization's List of Essential Medicines. It's used as an antidote to thallium or radiocaesium.
https://en.wikipedia.org/wiki/Prussian_blue_%28medical_use%29 [wikipedia.org]
Titanium dioxide is used in toothpaste, paint, and sunscreen. Nanoparticles of it may be harmful.
https://en.wikipedia.org/wiki/Titanium_dioxide [wikipedia.org]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3503962/ [nih.gov]