Class A (type D) CpG ODNs (CpG-A ODNs) contain a central palindromic phosphodiester (PO) CpG sequence and a PS-modified 3â poly-G tail. The poly G tails form intermolecular tetrads that result in high molecular weight ordered structures.
Why does a tornado form when cold and hot air meet? The collision of warm and cold air is not the direct cause of a tornado, nor is it absolutely necessary. When a cold air mass pushes into a warm air mass (this is called a câ¦old front) the warmer, less dense air is forced upwards.
Tornadoes are formed when hot air and cold air meet in a powerful storm, and the warm air begins spiralling upward, creating a funnel cloud. This funnel cloud forces objects on the ground and in the air around and upward, and can be strong enough to uproot trees, move cars and tear apart buildings.