Limits on variations of the quark masses, QCD scale, and fine structure constant

We perform calculations of the dependence of nuclear magnetic moments on quark masses and obtain limits on the variation of the fine structure constant $\alpha$ and ${(m}_q/{\Lambda }_{\mathrm{QCD}})$ from recent measurements of hydrogen hyperfine (21 cm) and molecular rotational transitions in quasar absorption systems, atomic clock experiments with hyperfine transitions in H, Rb, Cs, ${\mathrm{Yb}}^{+},$ ${\mathrm{Hg}}^{+},$ and optical transition in ${\mathrm{Hg}}^{+}.$ Experiments with ${\mathrm{Cd}}^{+},$ deuterium/hydrogen, molecular ${\mathrm{SF}}_6,$ and Zeeman transitions in ${}^3\mathrm{H}\mathrm{e}/\mathrm{X}\mathrm{e}$ are also discussed.