Ceria nanoparticles: biomedical applications and toxicity

Ceria nanoparticles(CeO_(2) NPs)have become popular materials in biomedical and industrial fields due to their potential applications in anti-oxidation,cancer therapy,photocatalytic degradation of pollutants,sensors,etc.Many methods,including gas phase,solid phase,liquid phase,and the newly proposed green synthesis method,have been reported for the synthesis of CeO_(2) NPs.Due to the wide application of CeO_(2) NPs,concerns about their adverse impacts on human health have been raised.This review covers recent studies on the biomedical applications of CeO_(2) NPs,including their use in the treatment of various diseases(e.g.,Alzheimer's disease,ischemic stroke,retinal damage,chronic inflammation,and cancer).CeO_(2) NP toxicity is discussed in terms of the different systems of the human body(e.g.,cytotoxicity,genotoxicity,respiratory toxicity,neurotoxicity,and hepatotoxicity).This comprehensive review covers both fundamental discoveries and exploratory progress in CeO_(2) NP research that may lead to practical developments in the future.

Individually resolved luminescence from closely stacked GaN/AlN quantum wells

Investigating closely stacked GaN/AlN multiple quantum wells(MQWs)by means of cathodoluminescence spectroscopy directly performed in a scanning transmission electron microscope,we have reached an ultimate spatial resolution ofσCL=1.8 nm.The pseudomorphically grown MQWs with high interface quality emit in the deep ultraviolet spectral range.Demonstrating the capability of resolving the 10.8 nm separated,ultra-thin quantum wells,a cathodoluminescence profile was taken across individual ones.Applying a diffusion model of excitons generated by a Gaussian-broadened electron probe,the spatial resolution of cathodoluminescence down to the free exciton Bohr radius scale has been determined.

Infrared stimulated emission with an ultralow threshold from low-dislocation-density InN films grown on a vicinal GaN substrate

Near-infrared stimulated emission from a high-quality InN layer under optical pumping was observed with a threshold excitation power density of 0.3 and 4 kW cm^(−2) at T=8 and 77 K,respectively.To achieve such a low threshold power density,vicinal GaN substrates were used to reduce the edge-component threading dislocation(ETD)density of the InN film.Cross-sectional transmission electron microscopy images reveal that the annihilation of ETDs can be divided into two steps,and the ETD density can be reduced to approximately 5×10^(8) cm^(−2) near the surface of the 5-μm-thick film.The well-resolved phonon replica of the band-to-band emission in the photoluminescence spectra at 9 K confirm the high quality of the InN film.As a result,the feasibility of InN-based photonic structures and the underlying physics of their growth and emission properties are demonstrated.