When particles are embedded in the ice near its bulk melting temperature,a premelted film forms between the particles and ice in a process known as"interfacial premelting".Under the influence of a temperatur...When particles are embedded in the ice near its bulk melting temperature,a premelted film forms between the particles and ice in a process known as"interfacial premelting".Under the influence of a temperature gradient,the premelted film varies in thickness,modulating the strength of ice-particle interactions and producing a net pressure that drives the particles to migrate towards higher temperatures in a phenomenon known as"thermal regelation".The phenomenon of thermal regelation is related to frost heave of soil,cryopreservation of organisms and methods of ice core paleoclimatology.In order to further investigate the principles of thermodynamics and dynamics in thermal regelation,we built a temperature gradient control platform and a single layer visual polydimethylsiloxane(PDMS)chip for thermal regelation experiments of individual silica particles.In the experiment,we measured the migration velocity of individual particles at different locations in the ice,and found that the thermal regelation of particles can be divided into high speed and low speed stages.As the particles approach the ice-water interface,the migration velocity increases dramatically.By combining the experimental data with the premelting theory,we found that the observed behavior is phenomenologically consistent with expectations for van der Waals force with radii of 12.5μm and 10μm.However,when the particle size was reduced to 7.5μm,the observed behavior was phenomenologically consistent with expectations for undelayed van der Waals force.In addition,under different temperature gradients and particle sizes,the thickness of the premelted film was maintained in the range of 20 nm-60 nm close to 273.15 K.However,under the same supercooling degree,the thickness of the premelted film increases with the increased of temperature gradient.Among the extracted parameters,the parameterλ,which was related to the van der Waals force,was linearly related to the temperature gradient.These experimental results not only provided important quantitative information for further understanding of thermal regelation but also provided a theoretical basis for optimizing related applications.展开更多
基金supported by The National Science Foundation for Distinguished Young Scholars of China(No.12102418)Zhejiang Provincial Natural Science Foundation of China(No.LQ21A020007)Youth Science and Technology Innovation Personnel Training Project(Category B)(No.2021YW48)。
文摘When particles are embedded in the ice near its bulk melting temperature,a premelted film forms between the particles and ice in a process known as"interfacial premelting".Under the influence of a temperature gradient,the premelted film varies in thickness,modulating the strength of ice-particle interactions and producing a net pressure that drives the particles to migrate towards higher temperatures in a phenomenon known as"thermal regelation".The phenomenon of thermal regelation is related to frost heave of soil,cryopreservation of organisms and methods of ice core paleoclimatology.In order to further investigate the principles of thermodynamics and dynamics in thermal regelation,we built a temperature gradient control platform and a single layer visual polydimethylsiloxane(PDMS)chip for thermal regelation experiments of individual silica particles.In the experiment,we measured the migration velocity of individual particles at different locations in the ice,and found that the thermal regelation of particles can be divided into high speed and low speed stages.As the particles approach the ice-water interface,the migration velocity increases dramatically.By combining the experimental data with the premelting theory,we found that the observed behavior is phenomenologically consistent with expectations for van der Waals force with radii of 12.5μm and 10μm.However,when the particle size was reduced to 7.5μm,the observed behavior was phenomenologically consistent with expectations for undelayed van der Waals force.In addition,under different temperature gradients and particle sizes,the thickness of the premelted film was maintained in the range of 20 nm-60 nm close to 273.15 K.However,under the same supercooling degree,the thickness of the premelted film increases with the increased of temperature gradient.Among the extracted parameters,the parameterλ,which was related to the van der Waals force,was linearly related to the temperature gradient.These experimental results not only provided important quantitative information for further understanding of thermal regelation but also provided a theoretical basis for optimizing related applications.
