Banded spherulites are formed by crystallization of a chiral polymer that is end-capped with chromophore. Induced circular dichroism (ICD) of the chromophore can be found in the crystallized chiral polymers, giving exclusive optical response of the ICD. The ICD signals are presumed to be driven by the lamellar twisting in the crystalline spherulites, and the exclusive optical activity is attributed to the chirality transfer from molecular level to macroscopic level. To verify the suggested mechanism, the sense of the lamellar twisting in the crystalline spherulite is determined using PLM for the comparison with the ICD signals of the chromophore in the electron circular dichroism spectrum. The conformational chirality of the chiral polymer is determined by the vibrational circular dichroism spectrum. On the basis of the chiroptical results, evolution of homochirality from helical polymer chains (conformational chirality) to lamellar twisting in the banded spherulite (hierachical chirality) is suggested.

Banded spherulite resulting from lamellar twisting due to the imbalanced stresses at opposite fold surfaces can be formed by isothermal crystallization of chiral polylactide and its blends with poly­(ethylene glycol) (PEG). Using a polarized light microscope, the handedness of the twisted lamella in banded spherulite is determined. With the same growth axis along the radial direction as evidenced by wide-angle X-ray diffraction (WAXD) for isothermally crystallized samples at different temperatures, the twisted lamellae of chiral polylactides (poly­(l-lactide) (PLLA) and poly­(d-lactide) (PDLA)) display opposite handedness. The split-type Cotton effect on the CO stretching motion of vibrational circular dichroism (VCD) spectra helps determine the helix handedness (i.e., conformational chirality). The results indicate that the conformational chirality can be defined by the molecular chirality through intramolecular chiral interactions. Moreover, the preferred sense of the lamellar twist in the banded spherulite corresponds to the twisting direction identified by the C–O–C vibration motion of VCD spectra, reflecting the role of intermolecular chiral interactions in the packing of polylactide helices. Similar results are obtained in the blends of chiral polylactides and poly­(ethylene glycol) (PEG, a polymer compatible with polylactide), indicating that the impact of chirality is intrinsic irrespective of the specific crystallization conditions. In contrast to the chiral polylactides, the spectrum of the crystalline stereocomplex that associates PLLA and PDLA shows VCD silence. The spectroscopic results are in line with the morphological observations. No banded spherulites are observed in the stereocomplex crystallites due to the symmetric packing of mirror L- and D-chain conformations in the fold surfaces and the crystallites core.

Patients with chronic mental illness are highly vulnerable to chronic respiratory problems. We examined the influence of mental disability on respiratory infection-related utilization risk in individuals with and without mental disabilities (MDs). A population-based, retrospective cohort design and two-part model were used to analyze respiratory infection-related utilization in individuals with MDs (MD group) and a matched reference group. The respiratory infection-related utilization rate in one year was lower in the MD group (53.8%) than in the reference group (56.6%). The odds ratios (ORs) were significantly higher among individuals with profound MDs (aOR = 1.10; 95% CI: 1.07–1.14) and those with a history of dental cavities (aOR = 1.16; 95% CI: 1.13–1.19) or periodontal disease (aOR = 1.22; 95% CI: 1.19–1.26) after controlling for covariables. The average number of visits was higher in the MD group (5.3) than in the reference group (4.0). The respiratory infection-related utilization rate and average number of visits were significantly higher in the mild, moderate and severe disabled groups with a history of periodontal disease, respectively, than that of the reference group. In conclusion, healthcare authorities must develop an incentive program to prevent respiratory infections among individuals with MDs.