Large area production of optical coatings and devices by the sol-gel process

[no abstract available

A Comparative Study on the Drivers of Forest Fires in Different Countries in the Cross-Border Area between China, North Korea and Russia

The occurrence and spread of forest fires are the result of the interaction of many factors. In cross-border areas, different fire management systems may lead to different forest fire driving factors. A comparative analysis of the forest fire driving factors in different countries can help to provide ideas for fire prevention and control. In this study, based on the logistic regression (LR) model and standardized coefficients, we determined the relative impact of forest fire driving factors in different countries, in the cross-border area between China, North Korea and Russia from 2001 to 2020, and established a forest fire probability and fire risk level division using a Kriging interpolation. The results show that the climate is the most important factor affecting the probability of forest fires in the cross-border area, followed by the topography and vegetation factors; human activities have the least influence. From a country-by-country perspective, the forest fires on the Chinese side were more affected by humans than on the North Korean and Russian sides and they were mainly concentrated in areas with a low altitude and high population density. The forest fires on the North Korean side and the Russian side were more affected by nature than on the Chinese side and were mainly concentrated in areas with a low altitude, high temperature and little rainfall. The high-risk areas for forest fires were mostly concentrated near the border between China, North Korea and Russia, where transboundary fires pose a great threat to forest resources and rare animals. This study shows that there is a significant difference between the impact of different forest fire management systems on fire conditions, and that active forest fire control policies can effectively reduce the damage caused by forest fires. Due to the complexity of the geopolitics in cross-border areas, transboundary firefighting faces certain difficulties. In the future, it will be necessary to strengthen the cooperation between countries and establish transboundary joint defenses against forest fires in order to protect the declining forest resources and the habitats of rare animals

Large area production of optical coatings and devices by the sol-gel process

[no abstract available

Stretchable and self-healable organometal halide perovskite nanocrystal-embedded polymer gels with enhanced luminescence stability

Stretchable and self-healing polymer gels with luminescent property are very promising materials for next generation soft optical devices. This work presents the preparation of self-healing and luminescent polymer gels by simply blending organometal halide perovskite nanocrystals (OHP NCs) with poly(dimethylsiloxane)-urea copolymer (PDMS-urea). On the one hand, the obtained luminescent gels are not only flexible, stretchable and relatively transparent, they also exhibit excellent self-healing capability due to the reversible hydrogen bonding network in the PDMS-urea copolymer. On the other hand, the embedding of OHP NCs (MAPbBr3 and MAPbI3 NCs) inside the hydrophobic PDMS-urea gel greatly improved the photoluminescence stability of OHP NCs against water. Their applications as phosphors for LEDs have been demonstrated. Both the MAPbBr3/PDMS-urea gel and MAPbI3/PDMS-urea gel can fully convert the blue emission of GaN chip to green and red emissions, respectively. These gels can be used as photoluminescent materials in flexible optical devices with good self-healing capability

Atomic Insights into Ti Doping on the Stability Enhancement of Truncated Octahedron LiMn₂O₄ Nanoparticles

Ti-doped truncated octahedron LiTixMn2-xO4 nanocomposites were synthesized through a facile hydrothermal treatment and calcination process. By using spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM), the effects of Ti-doping on the structure evolution and stability enhancement of LiMn2O4 are revealed. It is found that truncated octahedrons are easily formed in Ti doping LiMn2O4 material. Structural characterizations reveal that most of the Ti4+ ions are composed into the spinel to form a more stable spinel LiTixMn2−xO4 phase framework in bulk. However, a portion of Ti4+ ions occupy 8a sites around the {001} plane surface to form a new TiMn2O4-like structure. The combination of LiTixMn2−xO4 frameworks in bulk and the TiMn2O4-like structure at the surface may enhance the stability of the spinel LiMn2O4. Our findings demonstrate the critical role of Ti doping in the surface chemical and structural evolution of LiMn2O4 and may guide the design principle for viable electrode materials