RESULTS: A comparative study between two methods, (microwave-assisted and conventional heating approaches), was performed to synthesise a new quinazoline derivative from 2-(2-aminophenyl)-1H-benzimidazole and octanal to produce 6-heptyl-5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazoline (OCT). The compound was characterised using FTIR, 1H and 13C NMR, DIMS, as well as X-ray crystallography. The most significant peak in the 13C NMR spectrum is C-7 at 65.5 ppm which confirms the cyclisation process. Crystal structure analysis revealed that the molecule grows in the monoclinic crystal system P21/n space group and stabilised by an intermolecular hydrogen bond between the N1-H1A…N3 atoms. The crystal packing analysis showed that the molecule adopts zig-zag one dimensional chains. Fluorescence study of OCT revealed that it produces blue light when expose to UV-light and its' quantum yield equal to 26%. Antioxidant activity, which included DPPH· and ABTS·+ assays was also performed and statistical analysis was achieved via a paired T-test using Minitab 16 software with P
Methods: The nanocomposites were prepared via coprecipitation method at various molar ratios of B4 and EUS.
Results: At equal molar ratios, the obtained nanocomposite showed an intercalation selectivity that is preferential to EUS. However, the selectivity ratio of intercalated anions was shown to be capable of being altered by adjusting the molar ratio of intended guests during synthesis. Dual-guest nanocomposite synthesized with B4:EUS molar ratio 3:1 (ZEB [3:1]) showed an intercalation selectivity ratio of B4:EUS =53:47. Properties of ZEB (3:1) were monitored using powder X-ray diffractometer to show a basal spacing of 21.8 Å. Direct-injection mass spectra, Fourier transform infrared spectra, and ultraviolet-visible spectra confirmed the dual intercalation of both anions into the interlayer regions of dual-guest nanocomposite. The cytotoxicity study of dual-guest nanocomposite ZEB (3:1) on human dermal fibroblast cells showed no significant toxicity until 25 μg/mL.
Conclusion: Overall, the findings demonstrate successful customization of ultraviolet-ray absorbers composition in LDH host.
METHODS: This was a prospective, cross sectional study recruiting injured motorcyclists from Hanoi, Vietnam hospital. The participants were interviewed by a trained researcher. The participants' helmets were collected post-crash. Initially, the helmets were examined for their type and external characteristics. A 3 cm × 3 cm cut was made on the helmet in the impacted and non-impacted areas (control). These areas were investigated for evidence of POD and presence of micro-cracks and material disintegration. 50 participants were enrolled. Sources of information included questionnaire and laboratory analyses. The helmet factors of interest were age of the helmet, exposure of helmet to sunlight and rain (duration/day) and history of previous impact. Laboratory analyses included Fourier Transform Infra Red (FTIR) for degradation and scanning electron microscopy (SEM) for micro-structural examination.
RESULTS: Majority of the helmets was the open-face type, 40 (80.0%). 31 (62.0%) helmets aged less than three years (LTY) and 19 (38.0%) were three years old or more (MTY). 19 (61.3%) of the LTY helmets and 12 (63.2%) MTY helmets showed evidence of POD. The duration of helmet exposure to sunlight was between 93 to 6570 hours (mean 2347.74 hours; SD 1733.39). The SEM showed 15 helmets (30%) with micro-fractures, 21 helmets (42.0%) with material disintegration. Prolonged uv exposure to the ABS helmets resulted in changes in the helmet material in the form of material disintegration and microcracks and this association was statistically significant (p = 0.03).
CONCLUSION: POD occurs due to routine exposure to the ultraviolet light. Prolonged uv exposure affects outer shell surface material integrity.