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Additional file 1: Supplement 1. Subjects��� data.

Structural colors of 2D gratings are iridescent, color-tunable, and never fade, which renders them appealing for anti-counterfeiting applications. However, for advanced security, it still remains a challenge to completely hide the encrypted color patterns and reveal them on demand. In this work, a water-responsive photonic grating consisting of a micropillar array and a hydrogel overcoat with a similar refractive index, termed “hydrocipher”, is presented. The joint effect of stimuli-reversible refractive-index (mis)match and reconfigurable grating-based diffraction coloration enables a complete encryption of the structural color and rapid decryption. The photonic structure shows a strong iridescence due to the angle-dependent diffraction when the hydrogel overcoat is swollen from water. Upon drying, the micropillars bend and the refractive index contrast disappears, which dramatically lessens the diffraction intensity and renders the surface highly transparent. The dehydrated-to-hydrated state transition can occur within 1 s, enabling fast decryption. The color switching is highly reversible over a prolonged hydration/dehydration cycle, and the dehydrated hydrogel layer protects the delicate micropillar array from external mechanical stress. The creative combination of hydrogel material and the 2D grating structure offers a new and simple strategy for realizing reversible, durable, and fast-response cryptography with potentially broad impact on the anti-counterfeiting technology market.

Objective To compare the effects of neuromuscular electrical stimulation (NMES) to abdominal muscles and back muscles on postural balance in post-stroke hemiplegic patients. Methods Thirty post-stroke hemiplegic patients were prospectively enrolled and randomly assigned to one of the three groups: core muscle-strengthening exercise (CME) with NMES to abdominal muscles (group A), CME with NMES to back muscles (group B), and CME alone (group C). All subjects underwent their targeted interventions for 30 minutes each day, 5 days per week for 3 weeks under a conventional stroke rehabilitation program. Subjects were evaluated using Korean version of Berg Balance Scale (K-BBS), Trunk Impairment Scale (TIS), Korean version of Modified Barthel Index (K-MBI), Weight Distribution Index (WDI), and Stability Index (SI) just before and 3 weeks after intervention. Results Changes in K-BBS (p

Univariate model. (DOCX 15 kb)

Colloidal crystals exhibit structural color without any color pigment due to the crystals' periodic nanostructure, which can interfere with visible light. This crystal structure is iridescent as the resulting color changes with the viewing or illumination angle, which limits its use for printing or displays. To eliminate the iridescent property, it is important to make the packing of the colloidal nanoparticles disordered. Here, we introduce a drop-casting method where a droplet of a water- ethanol mixture containing monodisperse polymer-coated silica nanoparticles creates a relatively uniform and non-iridescent deposit after the droplet evaporates completely on a heated substrate. The uniformity is caused by a thermal Marangoni flow and fast evaporation effects due to the heated substrate, whereas non-iridescence is the outcome of short-range-ordered packing of nanoparticles by depletion attraction and friction effects produced by polymer brushes. We show that the colors of the final deposits from individual droplets remain unchanged while the viewing angle is varied under ambient light. We expect that the coating method is compatible with ink-jet printing and the uniformly coated self-assembled non-iridescent nanostructures have potential for color displays using reflection mode and other optical devices., Comment: Accepted in Physical Review Applied (2018)