We report on the application of Raman scattering as a probe to follow the structural evolution of TiO2 aerogels. We have traced the evolution of the 142 and 630 cm-1 Eg anatase peaks as a function of morphology. The results have been analyzed in terms of the q vector relaxation mechanism which predicts a unique relation between particle size and features of the Raman spectra. Since the phonon dispersion of anatase is not known, we have used the analogous rutile dispersion. There is good agreement between the particle sizes evaluated from the model and those determined by X-ray diffraction. Our results demonstrate that Raman spectroscopy can be an effective tool in monitoring the evolution of these aerogel systems.

When the raters have been trained by an experienced rater, the SEBT is a test with excellent reliability when used across multiple raters in different settings. This information adds to the body of knowledge that exists regarding the usefulness of the SEBT as an assessment tool in clinical and research practice. Establishing excellent interrater reliability with normalized and nonnormalized scores strengthens the evidence for using the SEBT, especially at multiple sites.

The kinetic energy of flying insect prey is a formidable challenge for orb-weaving spiders. These spiders construct two-dimensional, round webs from a combination of stiff, strong radial silk and highly elastic, glue-coated capture spirals. Orb webs must first stop the flight of insect prey and then retain those insects long enough to be subdued by the spiders. Consequently, spider silks rank among the toughest known biomaterials. The large number of silk threads composing a web suggests that aerodynamic dissipation may also play an important role in stopping prey. Here, we quantify energy dissipation in orb webs spun by diverse species of spiders using data derived from high-speed videos of web deformation under prey impact. By integrating video data with material testing of silks, we compare the relative contributions of radial silk, the capture spiral and aerodynamic dissipation. Radial silk dominated energy absorption in all webs, with the potential to account for approximately 100 per cent of the work of stopping prey in larger webs. The most generous estimates for the roles of capture spirals and aerodynamic dissipation show that they rarely contribute more than 30 per cent and 10 per cent of the total work of stopping prey, respectively, and then only for smaller orb webs. The reliance of spider orb webs upon internal energy absorption by radial threads for prey capture suggests that the material properties of the capture spirals are largely unconstrained by the selective pressures of stopping prey and can instead evolve freely in response to alternative functional constraints such as adhering to prey.

A systematic study is conducted on four microporous metal–organic framework compounds built on similar ligands but different structures, namely [Zn3(bpdc)3(bpy)]⋅4 DMF⋅H2O (1), [Zn3(bpdc)3(2,2′dmbpy)]⋅4 DMF⋅ H2O (2), [Zn2(bpdc)2(bpe)]⋅2 DMF (3), and [Zn(bpdc)(bpe)]⋅DMF (4) (bpdc=4,4′‐biphenyldicarboxylate; bpy=4,4′‐bipyridine; 2,2′dmbpy=2,2′‐dimethyl‐4,4′bipyridine; bpe=1,2‐bis(4‐pyridyl)ethane; DMF=N,N′‐dimethylformamide) to investigate their photoluminescence properties and sensing/detection behavior upon exposure to vapors of various aromatic molecules (analytes) including nitroaromatic explosives. The results show that all four compounds are capable of detecting these molecules in the vapor phase through fluorescence quenching or enhancement. Both electrochemical measurements and theoretical calculations are performed to analyze the analyte–MOF interactions, to explain the difference in signal response by different analytes, and to understand the mechanism of fluorescence quenching or enhancement observed in these systems. Interestingly, compound 3 also shows an emission frequency shift when exposed to benzene (BZ), chlorobenzene (ClBZ), and toluene (TO), which provides an additional variable for the identification of different analytes in the same category.