How the cookie crumbles
British scientists have discovered that cookies break because of how they cool. As a cookie cools, moisture moves from the centre to the edges, causing the center to shrink and the edges to expand. This places stress on the cookie, creating tiny cracks. The scientists bounced laser beams off of cookies as their temperature dropped, and the reflections of these beams formed patterns of light. The patterns changed when the cookies had cracks in them. Plots of the patterns allowed the researchers to calculate how much moisture, or humidity, would make the cookies shrink and expand. Manufacturers could use these findings to control the humidity of cookies as they cool and produce cookies that crumble less.
-Manoji Pereira
Source: Nature
Modified bacteria can spot arsenic
In Bangladesh, India, Chile, and Vietnam, natural deposits of arsenic contaminate groundwater. Old methods of testing for arsenic in the water supply are not always accurate, but Swiss scientists have found a more reliable way of detecting the toxin. E.coli bacteria, commonly found in the human digestive system, are naturally sensitive to arsenic and can be genetically modified to glow in the presence of it. The researchers tried adding different genes to the bacteria: one found in fireflies, one found in glowing jellyfish, and one that changes the bacteria’s colour from white to blue. So far, the E.coli with the firefly genes has proved to be the best for arsenic detection. The bacteria can be dried onto paper strips, making dipsticks that are very sensitive to the presence of arsenic and cheap to produce. The modified E.coli sticks are currently on trial in Vietnam.
-MP
Source: Nature
