SIMULATION AND MEASUREMENT OF FLOW FIELD IN MICROCHIP

Cancer(malignant tumor)is one of the serious threats to human life,causing 13%of all human deaths.A crucial step in the metastasis cascade of cancer is hematogenous spreading of tumor cells from a primary tumor.Thus,isolation and identification of cells that have detached from the primary tumor and circulating in the bloodstream(circulating tumor cells,CTCs)is considered to be a potential alternation to detect,characterize,and monitor cancer.Current methods for isolating CTCs are limited to complex analytic approaches that generate very low yield and purity.Here,we propose a high throughput 3D structured microfluidic chip integrated with surface plasmon resonance(SPR)sensor to isolate and identify CTCs from peripheral whole blood sample.The microfluidic velocity-field within the channel of the chip is mediated by an array of microposts protruding from upper surface of the channel.The height of microposts is shorter than that of the channel,forming a gap between the microposts and the lower surface of the channel.The lower surface of the channel also acts as the SPR sensor which can be used to identify isolated CTCs.Microfluidic velocity-field under different parameters of the arrayed microposts is studied through numerical simulation based on finite element method.Measurement on one of such fabricated microchips is conducted by our established optical Doppler tomography technique benefiting from its noninvasive,noncontact,and high-resolution spatialresolved capabilities.Both simulation and measurement of the microfluidic velocity-field within the structured channel demonstrates that it is feasible to introduce fluidic mixing and causes perpendicular flow component to the lower surface of the channel by the 3D structured microposts.Such mixing and approaching capabilities are especially desirable for isolation and identification of CTCs at the coated SPR sensor.

First-principles-based prediction of yield strength in the RhIrPdPtNiCu high-entropy alloy

High-entropy alloys are random alloys with five or more components,often near equi-composition,that often exhibit excellent mechanical properties.Guiding the design of new materials across the wide composition space requires an ability to compute necessary underlying material parameters via ab initio methods.Here,density functional theory is used to compute the elemental misfit volumes,alloy lattice constant,elastic constants,and stable stacking fault energy in the fcc noble metal RhIrPdPtNiCu.These properties are then used in a recent theory for the temperature and strain-rate dependent yield strength.The parameter-free prediction of 583 MPa is in excellent agreement with the measured value of 527 MPa.This quantitative connection between alloy composition and yield strength,without any experimental input,motivates this general density functional theory-based methodological path for exploring new potential high-strength high-entropy alloys,in this and other alloy classes,with the chemical accuracy of first-principles methods.