水的潜热:凝结,大气运动和冰啤酒

炎热的夏天,冰啤酒的易拉罐外壳会凝结一层水,啤酒也随之温度升高.这种空气中水分凝结释放热量的现象,叫做水的潜热释放.     

微观下的热

<正>在日常生活中,热传导现象很常见。宏观上热传导被看作能量在温度梯度场下的扩散行为,而这一输运过程取决于傅里叶定律给出的材料热导率。由傅里叶定律与能量守恒定律所衍生出的热传导方程,则描绘了温度在时间与空间中的分布。但是,这个宏观热传导方程留下了很多未解之谜。例如,为什么金刚石具有极高的热导率,而和它     

Stable water droplets on composite structures formed by embedded water into fully hydroxylated β-cristobalite silica

Using molecular dynamics simulations, we have revealed a novel wetting phenomenon with a droplet on composite structures formed by embedded water into(111) surface of β-cristobalite hydroxylated silica. This can be attributed to the formation of a composite structure composed of embedded water molecules and the surface hydroxyl(–OH) groups,which reduces the number of hydrogen bonds between the composite structure and the water droplet above the composite structure. Interestingly, a small uniform strain(±3%) applied to the crystal lattice of the hydroxylated silica surface can result in a notable change of the contact angles(> 40°) on the surface. The finding provides new insights into the correlation between the molecular-scale interfacial water structures and the macroscopic wettability of the hydroxylated silica surface.