Upper panel: GCE-corrected differential abundances as a function of T_c for 11 solar twins from Papers I and II. Gray points mark individual stars selected with –0.1 < [Fe/H] < 0.1 dex, ΔT_eff < 100 Κ, and Δ log ɡ < 0.1 dex. Colored symbols represent their mean elemental abundances in linear space: refractory elements (T_c > 1300 K) in orange, volatile elements in blue. The vertical dashed orange line indicates the T_c = 1300 Κ boundary. A weighted linear regression to the averaged data (including C and O) is shown as the solid orange line, with a shaded blue band denoting the 1σ confidence interval. The regression relation is $-{6.1}_{-1.9}^{+1.9}\times {10}^{-5}\times T_c+{0.10}_{-0.02}^{+0.02}$. A fit excluding C and Ο is shown as the dashed orange line. Lower panel: same but using the solar abundances from Lodders (2019), which yields $-{8.4}_{-5.4}^{+4.0}\times {10}^{-5}\times T_c+{0.07}_{-0.05}^{+0.07}$.