Eat bananas before downing a few beers. Afterwards, drink water with electrolyte powder before bed and Alka-Seltzer the next morning. Take painkillers. Sweat it out in a sauna. Put your head under the pillow and tell yourself “I’m never drinking again” When it comes to hangover preventions and cures, there are many such alchemy-like notions doing the rounds. They’re all a bit hit-and-miss, however, prompting researchers at one of Europe’s leading universities to come up with a “hydrogel” they say “could reduce the harmful and intoxicating effects of alcohol.” Developed at ETH Zurich and tested…