POSIXct format in Julia

Hello everyone
I am translating an R program into Julia.
I have a problem because I assign the type POSIXct (POSIXct class stores date/time values as the number of seconds since January 1, 1970) to one of the columns of my dataframe in R :

class(data$MaterialExpectedDate) <- "POSIXct" 

I can’t find the equivalent of this format in Julia. Do you know a way to get this format ?

Thank you,

julia> using Dates

julia> datetime2unix(DateTime(1970, 1, 1))

julia> datetime2unix(DateTime(1970, 1, 2))