When the total pressure is considered, as in chemical analysis and in thermodynamics it is often referred to as psia or absolute pressure of the substance or of the fluid which would then include the atmospheric pressure. It is important to include the subscript g or a to define which pressure is being noted. Psi can also be the difference between two pressures, be they gage or absolute. Psi is also used in materials engineering referring to the unit stress caused when a load is imposed on a structure or on a part.
Adenine is one of the two purine nucleobases (the other being guanine) used in forming nucleotides of the nucleic acids. In DNA, adenine binds to thymine via two hydrogen bonds to assist in stabilizing the nucleic acid structures. In RNA, which is used for protein synthesis, adenine binds to uracil.
1 A phosphate group. 2  A nitrogenous base Only four nitrogenous bases are present in DNA: thymine, cytosine, adenine and guanine. 3  The sugars and phosphates of the nucleotides bond strongly together to form a backbone to which these four bases connect, forming the rungs of the double helix. A phosphate group. 2  A nitrogenous base Only four nitrogenous bases are present in DNA: thymine, cytosine, adenine and guanine. 3  The sugars and phosphates of the nucleotides bond strongly together to form a backbone to which these four bases connect, forming the rungs of the double helix.