For Overlay Line Plot on Bar Graph Using Different Y-Axes. See here.
days = 0:5:35;
conc = [515,420,370,250,135,120,60,20];
temp = [29,23,27,25,20,23,23,27];
[AX,hBar,hLine] = plotyy(days,temp,days,conc,'bar','plot'); %u can switch order of 'bar' and 'plot'.
%Change the Axis properties
set(AX(1),'ycolor','r')
set(AX(2),'ycolor','b')
%Change Line properties
set(hLine, 'color', r)
%Change Bar properties
set(hBar, 'facecolor',...
