2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/43379The method of truncated Mellin moments in a solving QCD evolution equations of the nonsinglet structure functions $F_2^{NS}(x,Q^2)$ and $g_1^{NS}(x,Q^2)$ is presented. All calculations are performed within double logarithmic $ln^2x$ approximation. An equation for truncated moments which incorporates $ln^2x$ effects is formulated and solved for the unintegrated structure function $f^{NS}(x,Q^2)$. The contribution to the Bjorken sum rule coming from the region of very small $x$ is quantified. Further possible improvement of this approach is also discussed.17 pages, 3 figuresHigh Energy Physics - Phenomenologytext