Hollow, pure carbon cylinders, one-billionth of a metre in diameter
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/small-efficient
[2] http://admin.indiaenvironmentportal.org.in/category/author/sekhar
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/down-earth
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/copper
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/carbon-dioxide
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/solar-energy
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/energy-technology
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/united-states-america-us