Noun [edit]. viola â(plural violas). ( 1 music) A stringed instrument of the violin family, somewhat larger than a violin, played under the chin, and having a deeper tone. ( 2 music) An organ stop having a similar tone. ( 3 music) A 10-string steel-string acoustic guitar, used in Brazilian folk music.oun [edit]. viola â(plural violas). ( 1 music) A stringed instrument of the violin family, somewhat larger than a violin, played under the chin, and having a deeper tone. ( 2 music) An organ stop having a similar tone. ( 3 music) A 10-string steel-string acoustic guitar, used in Brazilian folk music.
Dipalmitoylphosphatidylcholine (DPPtdCho) is a phospholipid (and a lecithin) consisting of two palmitic acids attached of a phosphatidylcholine head-group and is the major constituent of many pulmonary surfactants. It is zwitterionic by virtue of having a negative charge on the phosphate group and a positive charge on the quaternary ammonium group.
This is a phospholipid with two 16-carbon saturated chains and a phosphate group with quaternary amine group attached. The DPPC is the strongest surfactant molecule in the pulmonary surfactant mixture. It also has higher compaction capacity than the other phospholipids, because the apolar tail is less bent.ecause during ventilation there is a variation of the lung surface area, the surfactant's interface concentration is not usually at the level of saturation. The surface increases during inspiration, which consequently opens space for new surfactant molecules to be recruited to the interface.