Phase Identification and Structure Solution by Three-Dimensional Electron Diffraction Tomography: Gd–Phosphate Nanorods

Hydrothermal synthesis of GdPO₄ in the presence of poly­(methacrylic acid) yields nanorods with a diameter of 15 nm and an aspect ratio of 20. Powder X-ray diffraction patterns showed that the GdPO₄ nanorods display peaks characteristics for both monoclinic and hexagonal structures. Three-dimensional electron diffraction tomography (3D EDT) was used to determine the structures <i>ab initio</i> on the basis of reciprocal volume reconstruction of electron diffraction data sets collected from single nanorods. The crystal structure of the monoclinic form was shown to be <i>P</i>2₁/<i>n</i>, corroborating previous work. We were able to solve the 3D structure of the hexagonal <i>P</i>6₂22 form, which has not been reported previously. Our work shows that 3D EDT is a powerful method that can be used for solving structures of single nanocrystals

Phase Identification and Structure Solution by Three-Dimensional Electron Diffraction Tomography: Gd–Phosphate Nanorods

Hydrothermal synthesis of GdPO₄ in the presence of poly­(methacrylic acid) yields nanorods with a diameter of 15 nm and an aspect ratio of 20. Powder X-ray diffraction patterns showed that the GdPO₄ nanorods display peaks characteristics for both monoclinic and hexagonal structures. Three-dimensional electron diffraction tomography (3D EDT) was used to determine the structures <i>ab initio</i> on the basis of reciprocal volume reconstruction of electron diffraction data sets collected from single nanorods. The crystal structure of the monoclinic form was shown to be <i>P</i>2₁/<i>n</i>, corroborating previous work. We were able to solve the 3D structure of the hexagonal <i>P</i>6₂22 form, which has not been reported previously. Our work shows that 3D EDT is a powerful method that can be used for solving structures of single nanocrystals

Multi-level toxicity assessment of engineered cellulose nanofibrils in <i>Daphnia magna</i>

<p>Cellulose nanofibril (CNF)-based materials are increasingly used in industrial and commercial applications. However, the impacts of CNF on aquatic life are poorly understood, and there are concerns regarding their potential toxicity. Using a combination of standard ecotoxicological tests and feeding experiments, we assessed the effects of CNF exposure (0.206–20.6 mg/L) on the feeding (food uptake and gut residence time) and life-history traits (growth and reproduction) in the cladoceran <i>Daphnia magna.</i> No mortality was observed in a 48 h acute exposure at 2060 mg/L. Moreover, a 21-day exposure at low food and moderate CNF levels induced a stimulatory effect on growth, likely driven by increased filtration efficiency, and, possibly, partial assimilation of the CNF by the animals. However, at low food levels and the highest CNF concentrations, growth and reproduction were negatively affected. These responses were linked to caloric restriction caused by dilution of the food source, but not an obstruction of the alimentary canal. Finally, no apparent translocation of CNF past the alimentary canal was detected. We conclude that CNF displays a low toxic potential to filter-feeding organisms and the expected environmental risks are low.</p