Let α > 0 be a constant, let ℓ ≥ 0 be an integer, and let Γ(z) denote the classical Euler gamma function. With the help of the integral representation for the Riemann zeta function ζ(z), by virtue of a monotonicity rule for the ratio of two integrals with a parameter, and by means of complete monotonicity and another property of the function 1 e t −1 and its derivatives, the authors present that,(1) for ℓ ≥ 0, the function 2010