Dr Watson, co-discoverer with Francis Crick of the double-helical structure of DNA, was responsible for suggesting the human-genome project in the first place.
The barrel heats up as a result of the hot expanding gases in the barrel and the friction from the bullets that are propelled by these hot gases along a helical path inside the barrel.
When the team seeded areas outside the tubes with mouse nerve cells the cells went exploring, sending their threadlike projections into the tubes and even following the curves of helical tunnels, the researchers report in an upcoming ACS Nano.