S1E11
Episode 11 (September 20, 2020)
Yucong Miao
Harvard University
Solomon Adera
University of Michigan
Xiao Yang
The Chinese University of Hongkong
Nanocalorimetry and its application in thin film shape memory alloys
Abstract:
Nanocalorimetry is a technique to do calorimetry on extremely small samples using arrays of micromachined calorimetry sensors. It is widely useful for studying phase transformations in thin film materials. I will talk about how we used differential nanocalorimetry to study the martensite-austenite transformation in CuZr-based shape memory alloys. Additionally, I will talk about resistance sensor arrays and their usage in screening for novel shape memory alloys.
Oil depletion from lubricated tubes during condensation
Abstract:
Due to advances in micro/nanofabrication, condensation heat transfer has seen a renaissance in recent years. Compared to conventional heat transfer surfaces, micro/nanostructured surfaces impregnated with lubricated oil have been demonstrated to improve condensation heat transfer by facilitating droplet nucleation, growth, and departure. The presence of micro/nanoscale roughness improves performance longevity by immobilizing the lubrication film. The enhancement, however, is short-lived due to the eventual loss of lubrication oil by departing droplets. Using high speed fluorescence imaging and thermogravimetric analysis, this work shows that (a) departing droplets leave behind satellite droplets that help to retain the oil in the wetting ridge, (b) the composition of the satellite droplets left behind is water, (c) the major source of oil depletion is the wetting ridge; not the wrapping layer, and (d) nearly half of the oil used for lubrication remains on the surface after 10 h condensation. We attribute the slow rate of oil depletion to the nanostructures on our tubes. The insights gained from this work can guide the rational design of long lasting lubricated surfaces for phase-change condensation.
Multifunctional Macromolecular Coatings Bioinspired from Salivary Acquired Pellicle
Abstract:
Salivary acquired pellicle (SAP) is a layer of saliva protein and glycoprotein and can stay on tooth surface for a long time. Statherin is the main compound of salivary acquire pellicle which is a 43 amino acid phosphopeptide consisting of proline and tyrosine. Statherin has a unique composition with a high degree of structural and charge asymmetry, present in human parotid and submandibular salivas. The N-terminated of the six amino acid DDDEEK of statherin have a strong adsorption to the hydroxyapatite surface. The purpose of this work was to design a series of short peptides modified PAMAM, metal-polyphenol net, CsgA, DOPA. After modified by DDDEEK, the macromolecule can adhesive to the materials surface endow the material surface with biominelization, antibacterial, antifouling and cell adhesion property. It has a wide application in tooth / bone repair materials, tooth / bone implant materials and tooth / bone tissue engineering field.