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It has been a long-standing puzzling problem that some glasses exhibit higher glass transition temperatures (denoting high stability) but lower activation energy for relaxations (denoting low stability).In this paper,the relaxation kinetics of the nanoconfined D-mannitol (DM) glass was studied systematically using a high-precision and high-rate nanocalorimeter.The nanoconfined DM exhibits enhanced thermal stability compared to the free DM.For example,the critical cooling rate for glass formation decreases from 200 K/s to below 1 K/s;the Tg increases by about 20 K-50 K.The relaxation kinetics is analyzed based on the absolute reaction rate theory.It is found that,even though the activation energy E* decreases,the activation entropy S* decreases much more for the nanoconfined glass that yields a large activation free energy G* and higher thermal stability.These results suggest that the activation entropy may provide new insights in understanding the abnormal kinetics of nanoconfined glassy systems.