By removing and purifying isotopes from graphite, Prof. Masahiro Nomura and his research group have demonstrated that heat removal is enhanced around 100 K (－173℃) by collective flows (phonon Poiseuille flows) caused by interaction of phonons. We have also clarified the theoretical criteria for the formation of phonon Poiseuille flow in graphite, which had not been clarified before. This is expected to further improve the heat removal performance of graphite, which is attracting attention as a heat-removal material. Prof. Tomoki Machida and his colleagues also participated in this joint research. The resulting paper was published in the online scientific journal Nature Communications on April 19.　
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