| 1. |
- Gao, Yun, et al.
(author)
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Microsecond-response perovskite light-emitting diodes for active-matrix displays
- 2024
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In: NATURE ELECTRONICS. - : NATURE PORTFOLIO. - 2520-1131. ; 7:6
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Journal article (peer-reviewed)abstract
- Perovskite light-emitting diodes (PeLEDs) could be of use in the development of active-matrix displays. However, due to ion migration in crystal structure, PeLEDs have electroluminescence rise times over milliseconds, which is problematic for the development of high-refresh-rate displays. Here, we show that the electroluminescence rise time of PeLEDs can be reduced to microseconds using an individual-particle passivation strategy. The approach is based on BF4 - ions that can passivate every nanocrystal in a perovskite emissive layer during film deposition. It leads to a defect-free film with discrete nanostructure and excellent crystallinity, which inhibits ion migration. Our strategy can be applied in perovskite nanocrystal films with different colours: red (635 nm), green (520 nm) and blue (475 nm). These PeLEDs all demonstrate response times within microseconds and high external quantum efficiencies of 22.7%, 26.2% and 18.1%, respectively. This allows us to create microsecond-response active-matrix PeLEDs that exhibit external quantum efficiencies above 20% at a display brightness of 500-3,000 cd m-2 for green devices with a resolution of 30 pixels per inch. We also develop microsecond-response red, green and blue active-matrix displays with 90 pixels per inch. An individual-particle passivation strategy that reduces ion migration in perovskite nanocrystal film can be used to make high-refresh-rate active-matrix displays with microsecond response times reduced by three orders of magnitude compared with typical perovskite light-emitting diodes.
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| 2. |
- Shi, Tingting, et al.
(author)
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The super-pangenome of Populus unveils genomic facets for its adaptation and diversification in widespread forest trees
- 2024
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In: Molecular Plant. - : Elsevier. - 1674-2052 .- 1752-9867. ; 17:5, s. 725-746
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Journal article (peer-reviewed)abstract
- Understanding the underlying mechanisms and links between genome evolution and adaptive innovations stands as a key goal in evolutionary studies. Poplars, among the world's most widely distributed and cultivated trees, exhibit extensive phenotypic diversity and environmental adaptability. In this study, we present a genus-level super-pangenome comprising 19 Populus genomes, revealing the likely pivotal role of private genes in facilitating local environmental and climate adaptation. Through the integration of pangenomes with transcriptomes, methylomes, and chromatin accessibility mapping, we unveil that the evolutionary trajectories of pangenes and duplicated genes are closely linked to local genomic landscapes of regulatory and epigenetic architectures, notably CG methylation in gene-body regions. Further comparative genomic analyses have enabled the identification of 142 202 structural variants across species that intersect with a significant number of genes and contribute substantially to both phenotypic and adaptive divergence. We have experimentally validated a ∼180-bp presence/absence variant affecting the expression of the CUC2 gene, crucial for leaf serration formation. Finally, we developed a user-friendly web-based tool encompassing the multi-omics resources associated with the Populus super-pangenome (http://www.populus-superpangenome.com). Together, the present pioneering super-pangenome resource in forest trees not only aids in the advancement of breeding efforts of this globally important tree genus but also offers valuable insights into potential avenues for comprehending tree biology.
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| 3. |
- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 4. |
- Cai, Weidong, 1991-, et al.
(author)
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Chirality Induced Crystal Structural Difference in Metal Halide Composites
- 2022
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In: Advanced Optical Materials. - : Wiley-V C H Verlag GMBH. - 2162-7568 .- 2195-1071. ; 10:16
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Journal article (peer-reviewed)abstract
- Incorporating chiral organic compounds into metal halide frames is a common and useful method to introduce chirality in metal halide composites. The structures of resulting racemic and chiral composites are usually considered to be nearly identical owing to similar chemical bonding. In this work, by incorporating chiral MBABr (bromide methylbenzylamine) into an inorganic frame, a significant crystallization difference between the resulting racemic and chiral metal halide composites is observed, as confirmed by both structural and spectroscopic measurements. In addition, the structural transformation in the chiral composites can also be induced by moisture, ascribed to the asymmetric hydrogen bonding in chiral materials. These results provide new insights for the future synthesis of chiral materials and open up new possibilities to advance the materials functionalities.
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| 5. |
- Cai, Weidong, et al.
(author)
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Multicolor light emission and multifunctional applications in double perovskite-Cs 2 NaInCl 6 by Cu + /Sb 3+co-doping
- 2024
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In: Chemical Engineering Journal. - : ELSEVIER SCIENCE SA. - 1385-8947 .- 1873-3212. ; 489
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Journal article (peer-reviewed)abstract
- Halide double perovskites managed by metal doping approach can exhibit dual emission colors, which have been considered as promising multicolor luminescent materials. However, an independent and stable emission at yellow region is missing owing to limited doping candidates, hindering the further commercialization of multicolor luminescence applications in double perovskites. In this work, we successfully obtain stable multicolor emission with PLQE (photoluminescence quantum yield) as high as 78% through developing the CuI doping strategy in Sb-Cs2NaInCl6. By introducing a high CuI feed ratio in airtight autoclave to compete the oxidization effect, the oxidization of CuI into CuII (detrimental factor for high PLQE due to serious quenching effect) is largely suppressed. With changing the CuI feed ratio, at least four distinct emission colors ranging from blue, purple, pink to yellow can be realized via changing the excitation wavelength. Depending on tunable multicolor emission, we further demonstrate the promise of our co-doped double perovskites in anti-counterfeiting technology and multicolor lighting devices. Our results open the way for enriching the optical applications of double perovskites based on multicolor emission.
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| 6. |
- Cai, Weidong, et al.
(author)
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Multicolor light emission in manganese-based metal halide composites
- 2022
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In: Applied Physics Reviews. - : AIP Publishing. - 1931-9401. ; 9:4
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Journal article (peer-reviewed)abstract
- Manganese-based organic-inorganic metal halide composites have been considered as promising candidates for lead-free emitters. However, in spite of their excellent luminescence properties in green and red regions, blue emission-a critical component for white light generation-from pristine manganese-based composites is currently missing. In this work, we successfully achieve blue luminescence center in manganese-based composites through selecting specific organic component methylbenzylamine (MBA). Our approach is fundamentally different from green and red emission in manganese-based composites, which result from manganese-halide frameworks. The coexistence of different luminescence centers in our manganese-based composites is confirmed by photoluminescence (PL) and photoluminescence excitation (PLE) results. As a result of different photoluminescence excitation responses of different emission centers, the resulting emission color can be tuned with selecting different excitation wavelengths. Specifically, a white light emission can be obtained with Commission Internationale de leclairage coordinates of (0.33, 0.35) upon the 330 nm excitation. We further demonstrate the promise of our manganese-based composites in the anti-counterfeiting technology and multicolor lighting. Our results provide a novel strategy for full-spectral emission in manganese-based organic-inorganic metal halide composites and lay a solid foundation for a range of new applications. (C) 2022 Author(s).
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| 7. |
- Cai, Weidong, 1991-
(author)
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Tunning Multicolor Light Emission in Lead-free Materials
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Perovskites are a class of compounds with the general formula ABX3 and becoming increasingly attractive recently. Because this kind of material possesses various advantages such as abundant raw materials, easy synthesis, excellent photoelectric properties, and short production process. As one of the applications for lead-based perovskites, the perovskite solar cells have quickly enhanced their PCE from 3.8% in 2009 to over 25% within a short period. However, the problems, such as instability of the ionic crystal nature and toxicity of lead, largely hinder the lead-based perovskites towards commercialization. Therefore, it is necessary to develop new lead-free materials as alternative to lead-based perovskites, where similar structures can be formed to inherit the excellent optoelectronic properties. Moreover, new properties can be achieved due to more abundant metal candidates in lead-free materials. Based on this, we develop different kinds of perovskite-structure-like lead-free materials such as organic inorganic hybrid materials, chiral materials and double perovskites. In addition to physical and chemical properties like photoluminescence, absorption, structure, etc., we further demonstrate their potential applications according to their unique properties such as multicolor light emission.We incorporate chiral MBA (methylbenzylamine) in inorganic metal system to obtain chiral lead-free organic inorganic hybrid materials, where significant crystallization difference is observed between rac and chiral halide compounds for the first time. Such difference is confirmed by spectrum and structural results. What’s more, we find that moisture can cause the structural transfer in chiral compounds, attributed to the asymmetric hydrogen bonding of chiral compounds. Our achievements open up new chance to improve our material property and provide new horizon for synthesis of chiral materials in the future.Then, we obtained blue emission center in Mn-based organic and inorganic compounds by choosing organic molecule MBA. The method has basic difference with the emissions in Mn based compounds. The coexisting two emission centers of our Mn based samples is verified by spectral results. Because two emission centers can induce different PL excitation responses, so that the excitation wavelengths are capable of manipulating the emission color. Specifically, we achieve CIE coordinates of (0.33, 0.35) with a white emission. The potential of our materials in anti-counterfeiting and multicolor lighting technology are further demonstrated. Our accomplishments explore a new approach for multicolor emission in Mn based materials.We finally obtained Sb3+/Cu+ co-doped Cs2NaInCl6 (CNIC) double perovskite by hydrothermal reaction which exhibits tunable dual emissions with PL quantum efficiency (PLQE) of 78%. Depending on different photoluminescence excitation (PLE) spectra between two emissions, multiple emission colors can be got by manipulating excitation wavelength. Interestingly, emission color gamut can be further tuned through manipulating the feeding ratio of CuI dopant, where warm color and cool color can be achieved separately. We further illustrated the application potential of our co-doped materials in the fileds of multicolor lighting devices and anti-counterfeiting. Our achievements open up a brand-new strategy for wider spectral luminescence of double perovskites and pace up the road for a series of new applications.
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| 8. |
- Karlsson, Max, et al.
(author)
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Role of chloride on the instability of blue emitting mixed-halide perovskites
- 2023
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In: FRONTIERS OF OPTOELECTRONICS. - : HIGHER EDUCATION PRESS. - 2095-2759. ; 16:1
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Journal article (peer-reviewed)abstract
- Although perovskite light-emitting diodes (PeLEDs) have seen unprecedented development in device efficiency over the past decade, they suffer significantly from poor operational stability. This is especially true for blue PeLEDs, whose operational lifetime remains orders of magnitude behind their green and red counterparts. Here, we systematically investigate this efficiency-stability discrepancy in a series of green- to blue-emitting PeLEDs based on mixed Br/Cl-perovskites. We find that chloride incorporation, while having only a limited impact on efficiency, detrimentally affects device stability even in small amounts. Device lifetime drops exponentially with increasing Cl-content, accompanied by an increased rate of change in electrical properties during operation. We ascribe this phenomenon to an increased mobility of halogen ions in the mixed-halide lattice due to an increased chemically and structurally disordered landscape with reduced migration barriers. Our results indicate that the stability enhancement for PeLEDs might require different strategies from those used for improving efficiency.
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| 9. |
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| 10. |
- Liu, Yang, et al.
(author)
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MiR-378a suppresses tenogenic differentiation and tendon repair by targeting at TGF-β2
- 2019
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In: Stem Cell Research and Therapy. - : Springer Science and Business Media LLC. - 1757-6512. ; 10:1
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Journal article (peer-reviewed)abstract
- Background: Tendons are a crucial component of the musculoskeletal system and responsible for transmission forces derived from muscle to bone. Patients with tendon injuries are often observed with decreased collagen production and matrix degeneration, and healing of tendon injuries remains a challenge as a result of limited understanding of tendon biology. Recent studies highlight the contribution of miR-378a on the regulation gene expression during tendon differentiation. Methods: We examined the tendon microstructure and tendon repair with using miR-378a knock-in transgenic mice, and the tendon-derived stem cells were also isolated from transgenic mice to study their tenogenic differentiation ability. Meanwhile, the expression levels of tenogenic markers were also examined in mouse tendon-derived stem cells transfected with miR-378a mimics during tenogenic differentiation. With using online prediction software and luciferase reporter assay, the binding target of miR-378a was also studied. Results: Our results indicated miR-378a impairs tenogenic differentiation and tendon repair by inhibition collagen and extracellular matrix production both in vitro and in vivo. We also demonstrated that miR-378a exert its inhibitory role during tenogenic differentiation through binding at TGFβ2 by luciferase reporter assay and western blot. Conclusions: Our investigation suggests that miR-378a could be considered as a new potential biomarker for tendon injury diagnosis or drug target for a possible therapeutic approach in future clinical practice.
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