19 research outputs found

    Solution-Processed InSb Quantum Dot Photodiodes for Short-Wave Infrared Sensing

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    Short-wave infrared (SWIR) photodiodes (PDs) based on colloidal semiconductor quantum dots (QDs) are characterized by the great possibility of device operation at a voltage bias of 0 V, spectral tunability, possible multiple-exciton generation, and high compatibility with printable technology, showing significant benefits toward medical applications. However, the light-absorbing layers of those PDs are hampered by a reliance on RoHS-restricted elements, such as Pb and Hg. Here, we report the SWIR PDs with light-absorbing layers of InSb QDs synthesized by a hot-injection approach using a combination of precursors, InBr3 and SbBr3. Impurity-free and secondary phase-free synthesis was realized by optimized reaction temperature and time, precursor ratio, and quenching of reaction. The diameters of the QDs were controlled in the 5.1–7.8 nm range for strengthened confinement of photogenerated carriers and tuning of bandgaps between 0.64 and 0.98 eV. These QDs were processed to terminate their surfaces with small molecular ligands, giving a narrow interparticle distance between neighboring QDs in a light-absorbing layer sandwiched by carrier transportation layers. The resulting PDs achieve a photoresponse of ∼550 ms at 0 V, with combining the best values of responsivity and external quantum efficiency of 0.098 A/W and 10.1% under a bias voltage of −1 V at room temperature even in ambient air

    Expression of FoxQ1 and NRXN3 in human normal brain and glioma tissues.

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    <p><b>A</b>, <i>NRXN3</i> and <i>FoxQ1</i> mRNA expression by RT-qPCR. The mRNA expression was analyzed in 30 matched primary glioblastoma tissues and the adjacent normal brain tissues. <b>B</b>, FoxQ1 expression levels correlated negatively with NRXN3 expression levels in glioblastoma samples (Pearson's correlation test <i>r</i> = −0.373; <i>P</i> = 0.042). <b>C,</b> Expression of FoxQ1 and NRXN3 protein in primary glioblastoma tissues and the adjacent normal brain tissues. Normal (N) and tumor (T) samples were analyzed by western blot. β-actin used as the loading control.</p

    The NRXN3 as a transcriptional target of FoxQ1.

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    <p><b>A</b>, Sequence and position of putative FoxQ1 binding sites on the NRXN3 promoter. <b>B</b>, ChIP assays were done with U-87MG cells. Chromatin fragments of the cells were immunoprecipitated with anti-FoxQ1 antibody or negative control IgG (middle) and subjected to PCR. We subjected 1% of the total cell lysates to PCR before immunoprecipitation as inputs. <b>C</b>, schematic structure of the NRXN3 promoter. The sequence of the FoxQ1 binding sites are shown in both wild-type (WT) and mutant (Mut) forms. <b>D+E</b>, Luciferase activity with or without mutations in NRXN3 promoter. U-87MG cells were transfected with the wild-type NRXN3 promoter or its mutants (D). SW1088 cells were co-transfected with the wild-type NRXN3 promoter or its mutants and pcDNA3.1-FoxQ1 (E). Luciferase activities were then determined. Three independent experiments were conducted. * <i>P</i><0.05</p

    FoxQ1 suppress the NRXN3 expression in human glioma cell lines.

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    <p><b>A</b>, Determination of FoxQ1 and NRXN3 expression in human glioma cell lines and normal human astrocytes using RT-qPCR (lower) and Western blot (upper). <b>B</b>, Up-regulation of NRXN3 mRNA and protein expression by overexpressing FoxQ1. FoxQ1 and NRXN3 expression levels in parental, control, SW1088-FoxQ1 cells by RT-qPCR (lower) and Western blot (upper). <b>C</b>, Down-regulation of NRXN3 mRNA and protein expression by depletion of FoxQ1 expression. FoxQ1 and NRXN3 expression in parental, control, and U-87MG-RNAi cells by RT-qPCR (lower) and Western blot (upper). <b>E+F</b>, Effect of FoxQ1 on NRXN3 promoter activity. Repression of the NRXN3 promoter in SW1088-FoxQ1 cells (E) and transactivation of the NRXN3 promoter in U-87MG-RNAi cells (F). Inhibition was calculated as a percentage relative to U-87MG cells and activation was calculated relative to SW1088 cells. Three independent experiments were conducted.</p

    Down-regulation of NRXN3 rescues the malignant phenotype of FoxQ1 down-regulated glioma cells <i>in vitro</i> and <i>in vivo</i>.

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    <p>A, Western blot (upper) and RT-qPCR (lower) analyses of FoxQ1 and NRXN3 expression in stable NRXN3-rescued U-87MG cells. B, Cells as in (A) were cultured in 96-well plates and analyzed by MTT assay. Cell proliferation curves were shown in 9 days. Three independent experiments were conducted. C, Cells as in (A) were examined for cell migration motility in 24-well plates with transwell chambers. Migrated cells were stained with crystal violet and counted under a light microscope. Three independent experiments were conducted. D, Glioma cells (1×10<sup>6</sup>) were implanted intracranially into nude mice. Mice were euthanized when they were moribund or on day 90. * Incidence: number of mice with tumor/number of mice injected. E, Kaplan-Meier estimates of overall survival time in nude injected with glioma cells. *<i>P</i><0.05.</p

    NMR, ESR, and Luminescence Characterization of Bismuth Embedded Zeolites Y

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    Thermal treatment of bismuth-embedded zeolite Y yields luminescent Bi<sup>+</sup> substructures without the formation of metallic nanoparticles. The structural and photophysical features of the resulting zeolite Y have been thoroughly characterized by using extensive experimental techniques including nuclear magnetic resonance (NMR), electron spin resonance (ESR), 2-dimentional excitation–emission and absorption spectra. NMR and ESR results indicate that some Al and oxygen are expelled from the zeolite Y framework after undergoing thermal treatment. The detailed analyses of luminescence and absorption spectra, coupled with TDDFT calculations, suggest that all Bi<sup>+</sup> substructures (i.e., Bi<sub>4</sub><sup>4+</sup>, Bi<sub>3</sub><sup>3+</sup>, Bi<sub>2</sub><sup>2+</sup>, and Bi<sup>+</sup>) are optically active in the near-infrared (NIR) spectral range. It is found that Bi<sup>+</sup>, Bi<sub>2</sub><sup>2+</sup>, Bi<sub>3</sub><sup>3+</sup>, and Bi<sub>4</sub><sup>4+</sup> units result in NIR emissions peaking at ca. 1050, 1135, 1145, and 1240/1285 nm, respectively. The emission lineshapes under diverse excitation wavelengths greatly depend on the Bi concentration and annealing temperature, as a result of the change in the relative concentration and the spatial distribution, as well as local structural features of Bi active species. Specifically, the above analyses imply that the reducing agents for Bi<sup>3+</sup> are water molecules as well as framework oxygen. These findings represent an important contribution to the understanding of the processes involved in the formation of Bi<sup>+</sup> and of the luminescence mechanisms of Bi<sup>+</sup> substructures in zeolite Y frameworks, which are not only helpful for the in-depth understanding of experimentally observed photophysical properties in other Bi-doped materials but also important for the development of novel photonic material systems activated by other p-block elements

    Synchrotron X-ray, Photoluminescence, and Quantum Chemistry Studies of Bismuth-Embedded Dehydrated Zeolite Y

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    For the first time, direct experimental evidence of the formation of monovalent Bi (i.e., Bi<sup>+</sup>) in zeolite Y is provided based on the analysis of high-resolution synchrotron powder X-ray diffraction data. Photoluminescence results as well as quantum chemistry calculations suggest that the substructures of Bi<sup>+</sup> in the sodalite cages contribute to the ultrabroad near-infrared emission. These results not only enrich the well-established spectrum of optically active zeolites and deepen the understanding of bismuth related photophysical behaviors, but also may raise new possibilities for the design and synthesis of novel hybrid nanoporous photonic materials activated by other heavier p-block elements

    Synchrotron X-ray, Photoluminescence, and Quantum Chemistry Studies of Bismuth-Embedded Dehydrated Zeolite Y

    No full text
    For the first time, direct experimental evidence of the formation of monovalent Bi (i.e., Bi<sup>+</sup>) in zeolite Y is provided based on the analysis of high-resolution synchrotron powder X-ray diffraction data. Photoluminescence results as well as quantum chemistry calculations suggest that the substructures of Bi<sup>+</sup> in the sodalite cages contribute to the ultrabroad near-infrared emission. These results not only enrich the well-established spectrum of optically active zeolites and deepen the understanding of bismuth related photophysical behaviors, but also may raise new possibilities for the design and synthesis of novel hybrid nanoporous photonic materials activated by other heavier p-block elements

    Machine-Learning-Driven Discovery of Mn<sup>4+</sup>-Doped Red-Emitting Fluorides with Short Excited-State Lifetime and High Efficiency for Mini Light-Emitting Diode Displays

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    The discovery of high-efficiency Mn4+-activated fluoride red phosphors with short excited-state lifetimes (ESLs) is urgent and crucial for high-quality, wide-color-gamut display applications. However, it is still a great challenge to design target phosphors with both short ESL and high luminescence efficiency. Herein, we propose an efficient machine learning approach based on a small dataset to establish the ESL prediction model, thereby facilitating the discovery of new Mn4+-activated fluorides with short ESLs. Such a model can not only accurately predict the ESLs of Mn4+ in fluorides but also quantify the impact of structure features on ESLs, therefore elucidating the “structure-lifetime” correlations. Guided by the correlations, two new Mn4+-doped tetramethylammonium (TMA)-based hybrid fluorides (TMA)2BF6:Mn4+ (B = Sn or Hf) with both short ESLs (τ ≤ 3.7 ms) and high quantum efficiencies (internal QEs > 92%, external QEs > 55%) have been discovered successfully. A prototype displayer with excellent performance (∼124% National Television Standards Committee (NTSC) color gamut) is assembled by employing a (TMA)2SnF6:Mn4+-based white Mini-LED backlight module, demonstrating its practical prospects in high-quality displays. This work not only brings promising candidates for Mn4+-doped fluoride phosphors but also provides a valuable reference for accelerating the discovery of new promising phosphors

    Machine-Learning-Driven Discovery of Mn<sup>4+</sup>-Doped Red-Emitting Fluorides with Short Excited-State Lifetime and High Efficiency for Mini Light-Emitting Diode Displays

    No full text
    The discovery of high-efficiency Mn4+-activated fluoride red phosphors with short excited-state lifetimes (ESLs) is urgent and crucial for high-quality, wide-color-gamut display applications. However, it is still a great challenge to design target phosphors with both short ESL and high luminescence efficiency. Herein, we propose an efficient machine learning approach based on a small dataset to establish the ESL prediction model, thereby facilitating the discovery of new Mn4+-activated fluorides with short ESLs. Such a model can not only accurately predict the ESLs of Mn4+ in fluorides but also quantify the impact of structure features on ESLs, therefore elucidating the “structure-lifetime” correlations. Guided by the correlations, two new Mn4+-doped tetramethylammonium (TMA)-based hybrid fluorides (TMA)2BF6:Mn4+ (B = Sn or Hf) with both short ESLs (τ ≤ 3.7 ms) and high quantum efficiencies (internal QEs > 92%, external QEs > 55%) have been discovered successfully. A prototype displayer with excellent performance (∼124% National Television Standards Committee (NTSC) color gamut) is assembled by employing a (TMA)2SnF6:Mn4+-based white Mini-LED backlight module, demonstrating its practical prospects in high-quality displays. This work not only brings promising candidates for Mn4+-doped fluoride phosphors but also provides a valuable reference for accelerating the discovery of new promising phosphors
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