Lauryldimethylamine oxide Lauryldimethylamine oxide Lauryldimethylamine oxide (LDAO), also known as dodecyldimethylamine oxide (DDAO), is an amine oxide based nonionic surfactant, with a C (dodecyl) alkyl tail. It is one of the most frequently-used surfactants of this type. Like other amine oxide based surfactants it is antimicrobial, being effective against common bacteria such as "S. aureus" and "E. coli", however it is also non-denaturing and may be used to solubilize proteins. At high concentrations, DDAO forms liquid crystalline phases. Despite having only one polar atom that is able to interact with water – the oxygen atom (the quaternary nitrogen atom is hidden from
I Should Have Known Better solo) and thus draws a line under a significant period of their early music. The song's middle sixteen section features George Harrison's brand new Rickenbacker 360/12 12-string guitar. The mono and stereo versions have slightly different harmonica introductions. In the stereo version, the harmonica drops out briefly. Also, a noticeably clumsy and audible tape edit is heard during the second chorus between "You're gonna say you love me too, oh," and "And when I ask you to be mine." In the UK, "I Should Have Known Better" appeared on "A Hard Day's Night" and was released on 10 July 1964.