Core Ideas
Quantified high‐temperature intensity, frequency, and duration as HDH index.High‐temperature episodes between booting and flowering increased significantly.High‐temperature episodes had a significant negative effect on rice yield.
Booting and flowering stages of rice are most sensitive to high‐temperature episodes. However, the effect of spatial‐temporal characteristics of high‐temperature episodes on booting and flowering stages in the middle‐season rice cropping region of China were less commonly found in the literature. A data analysis of historical climate and rice yield was conducted to characterize the spatial and temporal variability of high‐temperature episodes between booting and flowering stages and their impact on middle‐season rice grain yield in China. Three high‐temperature indices, including high‐temperature hours (HH), high‐temperature intensity (HI), and high‐temperature degree hours (HDH), were developed to quantify the high‐temperature intensity, frequency, and duration based on maximum temperature records of the last 30 yr from 219 stations in the main middle‐season rice cropping area of China. The HH and HI indices between booting and flowering stages increased significantly in all subregions. Especially in the Central China (CC) subregion, high‐temperature episodes were more severe than those in the East China (EC) subregion and Southwest (SW) subregion. The HDH index, considering the duration and intensity of high‐temperature episodes, was required to describe the correlation between high‐temperature episodes and yield variability. Significant negative (p < 0.05) impacts of the variability of high‐temperature episodes on the observed grain yield were found in all subregions. Rice yield would decrease by 113.9 kg ha−1, 19.1 kg ha−1, and 22.2 kg ha−1 with an HDH increase of 1.0°C·d in the EC, CC, and SW subregions, respectively. High‐temperature episodes were detrimental to middle‐season rice production of China.
Large-sized ZnSe nanocrystals are expected to emit pure-blue-light between 455-475 nm for display applications, however, haven’t been achieved up to date. By analyzing the influence of the reactivity of Zn and Se precursors, we found that the final size of ZnSe nanocrystals via hot-injection has a critical value that can be varied by ligands or precursors. To describe the key factors in determining the final size of ZnSe nanocrystals, we propose a nuclei number-considered LaMer model based on the Maxwell-Boltzmann distribution of crystal embryos. As a result, a general strategy of reactivity-controlled epitaxial growth (RCEG) was developed to synthesize large-sized ZnSe nanocrystals through sequential injection of high-reactivity and low-reactivity Zn (Se) precursors. The resulted large-sized ZnSe nanocrystals show pure-blue emission between 455-470 nm. We further fabricated efficient and stable large-sized ZnSe/ZnS core-shell nanocrystals with photoluminescence quantum yields up to 60%. Moreover, the RCEG strategy is versatile to synthesize large-sized CdSe and PbSe nanocrystals with average size over 35 nm. The hybridization of quantum confined effects and classical surface effects in these large-sized semiconductor nanocrystals, which will open up new directions for fundamental research and application explorations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.