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To study the seed dormancy and germination mechanism of Xanthoceras sorbifolium, the seeds of four cultivars [‘Putong’(PT),‘Qihong’(QH), ‘Wofeng’(WF) and‘Woshi’(WS)] were stored at -20 ℃ for different periods (30, 60, 90, 120, 150 d). The seed germination indexes were determined in each treatment, and the changes of reserve substance and hormone content were also analyzed in three stages including before storage, after storage, and 7 days of germination. The results were as follows: (1) Cold storage could significantly promote the germination rate and germination potential of small seeds (PT, QH). The best treatment was cold storage for 60 d, and the germination rate was up to 48.3% and 58.3%, respectively. The effects of cold storage on large seeds (WF and WS) was lower than that of small seeds. (2) The kernel oil content, seed shell thickness (SST) in four cultivar seeds all decreased significantly during periods of cold storage and germination, especially in 3-7 days of germination, the oil content and SST (except WS cultivar) decreased notably. However, water content in kernels increased rapidly within 1-3 days of germination and then slowly increased to the peak value on the 7th day. The contents of soluble sugar in kernels increased significantly at the 3-4 days of germination. (3) Cold storage increased GA/ABA and tHor/ABA ratios in small seeds (PT, QH), promoted oil degradation, made seed shell thinning and break seed dormancy. In conclusion, the main factors leading to dormancy in X. sorbifolium seeds are larger in size, higher shell thickness and more hardness, physiological post-ripening, and belongs to comprehensive dormancy type. Cold storage at -20 ℃ for 60 d can improve the germination rate of PT, QH and WF seeds, reduces dormancy degree, while the cold storage time of WS seeds needs prolonging to 150 d. The method using -20 ℃ storage with wet sand germination is a rapid and simple method to promote X. sorbifolium seeds germination. This study provides a reference for the promotion of superior varieties and the research on the seed breaking dormancy mechanism in X. sorbifolium.

Current X-ray imaging technologies involving flat-panel detectors have difficulty in imaging three-dimensional objects because fabrication of large-area, flexible, silicon-based photodetectors on highly curved surfaces remains a challenge.sup.1-3. Here we demonstrate ultralong-lived X-ray trapping for flat-panel-free, high-resolution, three-dimensional imaging using a series of solution-processable, lanthanide-doped nanoscintillators. Corroborated by quantum mechanical simulations of defect formation and electronic structures, our experimental characterizations reveal that slow hopping of trapped electrons due to radiation-triggered anionic migration in host lattices can induce more than 30 days of persistent radioluminescence. We further demonstrate X-ray luminescence extension imaging with resolution greater than 20 line pairs per millimetre and optical memory longer than 15 days. These findings provide insight into mechanisms underlying X-ray energy conversion through enduring electron trapping and offer a paradigm to motivate future research in wearable X-ray detectors for patient-centred radiography and mammography, imaging-guided therapeutics, high-energy physics and deep learning in radiology. Using lanthanide-doped nanomaterials and flexible substrates, an approach that enables flat-panel-free, high-resolution, three-dimensional imaging is demonstrated and termed X-ray luminescence extension imaging., Author(s): Xiangyu Ou [sup.1] , Xian Qin [sup.2] , Bolong Huang [sup.3] , Jie Zan [sup.1] , Qinxia Wu [sup.1] , Zhongzhu Hong [sup.1] , Lili Xie [sup.1] , Hongyu [...]

Long‐lasting radioluminescence scintillators have recently attracted substantial attention from both research and industrial communities, primarily due to their distinctive capabilities of converting and storing X‐ray energy. However, determination of energy‐conversion kinetics in these nanocrystals remains unexplored. Here we present a strategy to probe and unveil energy‐funneling kinetics in NaLuF4:Mn2+/Gd3+ nanocrystal sublattices through Gd3+‐driven microenvironment engineering and Mn2+‐mediated radioluminescence profiling. Our photophysical studies reveal effective control of energy‐funneling kinetics and demonstrate the tunability of electron trap depth ranging from 0.66 to 0.96 eV, with the corresponding trap density varying between 2.38×105 and 1.34×107 cm−3. This enables controlled release of captured electrons over durations spanning from seconds to 30 days. It allows tailorable emission wavelength within the range of 520–580 nm and fine‐tuning of thermally‐stimulated temperature between 313–403 K. We further utilize these scintillators to fabricate high‐density, large‐area scintillation screens that exhibit a 6‐fold improvement in X‐ray sensitivity, 22 lp/mm high‐resolution X‐ray imaging, and a 30‐day‐long optical memory. This enables high‐contrast imaging of injured mice through fast thermally‐stimulated radioluminescence readout. These findings offer new insights into the correlation of radioluminescence dynamics with energy‐funneling kinetics, thereby contributing to the advancement of high‐energy nanophotonic applications. [ABSTRACT FROM AUTHOR]

The growing demands for X-ray imaging applications impose diverse and stringent requirements on advanced X-ray detectors. Among these, flexibility stands out as the most expected characteristic for next-generation X-ray detectors. Flexible X-ray detectors can spatially conform to nonflat surfaces, substantially improving the imaging resolution, reducing the X-ray exposure dosage, and enabling extended application opportunities that are hardly achievable by conventional rigid flat-panel detectors. Over the past years, indirect- and direct-conversion flexible X-ray detectors have made marvelous achievements. In particular, microscale and nanoscale engineering technologies play a pivotal role in defining the optical, electrical, and mechanical properties of flexible X-ray detectors. In this Perspective, we spotlight recent landmark advancements in flexible X-ray detectors from the aspects of micro/nano engineering strategies, which are broadly categorized into two prevailing modalities: materials-in-substrate and materials-on-substrate. We also discuss existing challenges hindering the development of flexible X-ray detectors, as well as prospective research opportunities to mitigate these issues.

Solution-processed scintillators hold great promise in fabrication of low-cost X-ray detectors. However, state of the art of these scintillators is still challenging in their environmental toxicity and instability. In this study, we develop a class of tetradecagonal CuI microcrystals as highly stable, eco-friendly, and low-cost scintillators that exhibit intense radioluminescence under X-ray irradiation. The red broadband emission is attributed to the recombination of self-trapped excitons in CuI microcrystals. We demonstrate the incorporation of such CuI microscintillator into a flexible polymer to fabricate an X-ray detector for high-resolution imaging with a spatial resolution up to 20 line pairs per millimeter (lp mm -1 ), which enables sharp image effects by attaching the flexible imaging detectors onto curved object surfaces., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Hong, Luo, Wu, Wu, Chen, Yang, Dai, Jiang, Chen, Sun and Xie.)

Detection of haloalkanes is of great industrial and scientific importance because some haloalkanes are found serious biological and atmospheric issues. The development of a flexible, wearable sensing device for haloalkane assays is highly desired. Here, we develop a paper-based microfluidic sensor to achieve low-cost, high-throughput, and convenient detection of haloalkanes using perovskite nanocrystals as a nanoprobe through anion exchanging. We demonstrate that the CsPbX 3 (X = Cl, Br, or I) nanocrystals are selectively and sensitively in response to haloalkanes (CH 2 Cl 2 , CH 2 Br 2 ), and their concentrations can be determined as a function of photoluminescence spectral shifts of perovskite nanocrystals. In particular, an addition of nucleophilic trialkyl phosphines (TOP) or a UV-photon-induced electron transfer from CsPbX 3 nanocrystals is responsible for achieving fast sensing of haloalkanes. We further fabricate a paper-based multichannel microfluidic sensor to implement fast colorimetric assays of CH 2 Cl 2 and CH 2 Br 2 . We also demonstrate a direct experimental observation on chemical kinetics of anion exchanging in lead-halide perovskite nanocrystals using a slow solvent diffusion strategy. Our studies may offer an opportunity to develop flexible, wearable microfluidic sensors for haloalkane sensing, and advance the in-depth fundamental understanding of the physical origin of anion-exchanged nanocrystals., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Xie, Zan, Yang, Wu, Chen, Ou, Lin, Chen and Yang.)

Solid-state polymer electrolytes (SPEs) have great processing flexibility and electrode-electrolyte contact and have been employed as the promising electrolytes for lithium metal batteries. Among them, poly(ethylene oxide) (PEO)-based SPEs have attracted widespread attention because of easy synthesis, low mass density, good mechanical stability, low binding energy with lithium salts, and excellent mobility of charge carriers. In order to overcome the low room-temperature ionic conductivity and the poor thermodynamic stability in high-voltage devices (>4.2 V) of the PEO materials, composition modulations by incorporating PEO with inorganic and/or organic components have been designed, which could effectively enable the applications of PEO-based SPEs with widened electro-stable voltage ranges. In this mini review, we describe recent progresses of several kinds of PEO composite structures for SPEs, and we compare the synthesis strategies and properties of these SPEs in lithium batteries. Further developments and improvements of the PEO-based materials for building better rechargeable batteries are also discussed., (Copyright © 2020 Zhao, Wu, Ma and Yang.)