  We give an interpretation of quantum Serre of Coates and Givental as a
duality of twisted quantum D-modules. This interpretation admits a
non-equivariant limit, and we obtain a precise relationship among (1) the
quantum D-module of X twisted by a convex vector bundle E and the Euler class,
(2) the quantum D-module of the total space of the dual bundle E^\vee over X,
and (3) the quantum D-module of a submanifold Z\subset X cut out by a regular
section of E. When E is the anticanonical line bundle K_X^{-1}, we identify
these twisted quantum D-modules with second structure connections with
different parameters, which arise as Fourier-Laplace transforms of the quantum
D-module of X. In this case, we show that the duality pairing is identified
with Dubrovin's second metric (intersection form).
