LAS-SERS can detect the analytes of highly diluted solutions as low as sub-pico-molar concentration from only 20 μL solutions.

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We study experimentally the formation of a dual hierarchical jetting pattern in dry dense particle media subjected to the radially divergent shock loadings in a radial Hele-Shaw cell. The distinct internal and external jetting patterns were formed on the internal and external surfaces of a ring at different times, respectively. The former features dozens of radially aligned fine filaments. By contrast, the latter consists of a large number of small spikes. Once the internal jets are fully developed, a novel proportionate growth is observed, in which distinguishable structures of the overall pattern all grow at the same rate until the interaction between the internal and external jets becomes significant, leading to the inversion of the internal jetting pattern. Although the external jetting is found to be an instability of a Rayleigh-Taylor (RT) type, the internal jetting exhibits a much delayed onset and slower early-stage growth compared with the RT instability, indicating different underlying physics.

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This research highlights the application of multi-angle attenuated total reflection (ATR) infrared (IR) spectroscopy method in investigating the migration of additives from the bulk toward the surface which happens in the epoxy coating. Concentration profiles of additives such as low molecular polyamide 651 (LMPA 651) and 2,4,6 -tris (dimethylaminomethyl) phenol (DMP-30) were studied. Analysis of the shape of the additives concentration profiles revealed the existence of enrichment region and indicated the migration phenomenon of additives in epoxy coating during natural aging and accelerated aging processes. The changes of the additives concentration determined by the ATR-IR method were consistent with the results obtained by FTIR analysis and gravimetric analysis. The result shows that the ATR-IR method is very promising for investigating the surface chemical changes in epoxy coating due to its nondestructive testing, conveniency, and high efficiency. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40051.