May 28, 2014 - 06:02 PMInvestment_U Back in January, I wrote a column explaining the supply-demand squeeze in nickel. One way I suggested to play the nickel squeeze, the iPath Dow Jones-AIG Nickel Total Return Sub-Index ETN (NYSE: JJN), is up 38% from my recommendation. Did you buy that fund? Well, if you didn't, there's no need to kick yourself. The nickel run isn't over. In fact, if anything, the supply/demand squeeze powering nickel's surge is likely to get stronger. The biggest user of nickel is China. Nickel is used to make stainless steel, and China makes a lot of...