additional points discussed have dealt with the connection with the conventional particle contrast parameters ( section 4 and equations ( 44 ) - ( 48 ) ) , the effect of heterogeneity in particle composition and systems comprising two homomacromolecules ( equations ( 21 ) - ( 24 ) ) , the effect of hydrogen-deuterium substitution on mass density and scattering length density increments ( equations ( 42 ) and ( 43 ) ) .
C0020275
hydrogen
C0011744
deuterium