Let G denote the Adams
summand of connective unitary K-theory spectrum at the odd prime integer p. In
this paper, we study maps ϕ : G → G which have two properties
ϕ∗= 0 : π0(G) → π0(G),
ϕ∗(v) = p𝜖v with the unit 𝜖 ∈ Z(p)×,
where π∗(G) = Z(p)[v] and |v| = 2(p − 1). An example of such operations is the Adams
operation ψp+1− 1, and we will give an elementary proof of non-existence of elements
of modp Hopf invariant one.