\begin{table}%t5 
\caption{\label{tab:elevol}Rate of change of the mean mass fractions of $^{4}$He, $^{12}$C,   and $^{16}$O in the 2D model~hefl.2d.b within the first $40~000$~s ($R_i$; in units of $10^{-9}~{\rm s}^{-1}$), and within the time interval $40~000~{\rm s} \le t \le 130~000~{\rm s}$ ($R_f$; in units of $10^{-9}~{\rm s}^{-1}$) with the initial~$X_i$ and final~$X_f$ mass fractions (in units of~10$^{-3}$), respectively.}
%\centering
\small
\begin{tabular}{lllll} 
\hline
\hline
Element & $R_i$ & $R_f$ & $X_i$ & $X_f$ \\[2pt]
\hline 
%&&&& \\[-8pt]
$^{4}$He &  +7.74 &  --7.85 &  0.975  & 0.974 \\
$^{12}$C &  --7.41 &  +7.71 &  5.502  & 5.918 \\
$^{16}$O &  --0.58 &  +1.13 &  0.927  & 1.008 \\
\hline
\end{tabular} 
\end{table}