Liquid – liquid phase separation morphologies in ultra-white beetle scales and a synthetic equivalent

Cyphochilus beetle scales are amongst the brightest structural whites in nature, being highly opacifying whilst extremely thin. However, the formation mechanism for the voided intra- scale structure is unknown. Here we report 3D x-ray nanotomography data for the voided chitin networks of intact white scales of Cyphochilus and Lepidiota stigma. Chitin-filling frac- tions are found to be 31 ± 2% for Cyphochilus and 34 ± 1% for Lepidiota stigma, indicating previous measurements overestimated their density. Optical simulations using finite- difference time domain for the chitin morphologies and simulated Cahn-Hilliard spinodal structures show excellent agreement. Reflectance curves spanning filling fraction of 5-95% for simulated spinodal structures, pinpoint optimal whiteness for 25% chitin filling. We make a simulacrum from a polymer undergoing a strong solvent quench, resulting in highly reflective ( 94%) white films. In-situ X-ray scattering confirms the nanostructure is formed through spinodal decomposition phase separation. We conclude that the ultra-white beetle scale nanostructure is made via liquid–liquid phase separation

Supplementary material from “Optically-ambidextrous circularly-polarized reflection from the chiral cuticle of the scarab beetle <i>Chrysina resplendens</i>”

Figure S1 shows experimental measurements of circular polarization reflectance for a sample of eighty positions on the dorsal surface of the elytron. The results indicate that the main features of the CP spectra are consistently present across the sample of locations, and that some variation in the relative intensities and spectral positions of the features is observed. Figure S2 shows experimental measurements of circular polarization reflectance, performed on a prepared piece of elytron following removal of the endocuticle. Seven sets of measurements were made for incidence upon the dorsal surface and for incidence upon the exposed surface of the underside of the exocuticle. The results support the view that the spectra shown in figure 3b are typical of the exocuticle for incidence upon its exposed underside surface. The results also show that for incidence upon the dorsal surface the main spectral features seen in figure S1 were still observed following endocuticle removal. Figure S3 shows examples of SEM images of fractured sections of the exocuticle of the elytron. Figure S4 shows a schematic of the circular-polarization reflectance measurement setup

Supplementary material from “Optically-ambidextrous circularly-polarised reflection from the chiral cuticle of the scarab beetle Chrysina resplendens”

Figure S1 shows experimental measurements of circular polarisation reflectance for a sample of eighty positions on the dorsal surface of the elytron. The results indicate that the main features of the CP spectra are consistently present across the sample of locations, and that some variation in the relative intensities and spectral positions of the features is observed. Figure S2 shows experimental measurements of circular polarisation reflectance, performed on a prepared piece of elytron following removal of the endocuticle. Seven sets of measurements were made for incidence upon the dorsal surface and for incidence upon the exposed surface of the underside of the exocuticle. The results support the view that the spectra shown in figure 3b are typical of the exocuticle for incidence upon its exposed underside surface. The results also show that for incidence upon the dorsal surface the main spectral features seen in figure S1 were still observed following endocuticle removal. Figure S3 shows examples of SEM images of fractured sections of the exocuticle of the elytron. Figure S4 shows a schematic of the circular-polarisation reflectance measurement setup

Mouchet et al., 2016, Proc. R. Soc. B, Primary Data

Reflectance spectra; Excitation spectra; Emission spectra; Time-resolved Fluorescence Intensity - Further information: see related article

Supplementary Figures from Wing scale ultrastructure underlying convergent and divergent iridescent colours in mimetic <i>Heliconius</i> butterflies

Figure S1 Representative small angle X-ray scattering data for a region of a H. sara and the radial integrations of this 2d pattern; Figure S2 Dark field microscopy images; Figure S3 Reflectance spectra for H. sara from Panama and Ecuador; Figure S4 Neighbour joining phylogenetic tree of Heliconius species based on 745 bp of mitochondrial CoI sequence; Figure S5. Tetrahedral colour space plot