| 1. |
- 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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| 2. |
- Nie, Junyang, et al.
(author)
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Systematic study on size and temporal dependence of micro-LED arrays for display applications
- 2023
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In: Photonics Research. - 2327-9125. ; 11:4, s. 549-557
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Journal article (peer-reviewed)abstract
- Micro-LEDs are one of the most promising candidates for next-generation displays, yet they are inconvenienced by the efficiency reduction induced by the sidewall defects when pursuing further scaled-down device dimensions. We have systematically investigated both the size and temporal dependence of micro-LEDs. Micro-LED arrays with a mesa size ranging from 7 to 100 μm were prepared for display purposes. The luminance and external quantum efficiency (EQE) were measured and discussed. Surprisingly, micro-LED arrays with a smaller mesa size exhibit a higher EQE under 100 ns pulse duration operation when compared with longer pulse duration operations. Under certain short-pulsed excitation, a 7 × 7 μm2 micro-LED array even exhibits a >20% higher EQE as compared to the direct current (DC) or the long duration pulse operation condition.We thus concluded that the notorious efficiency reduction induced by sidewall defects in small-sized micro-LED arrays could be significantly reduced by applying short-pulse voltages.
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| 3. |
- Pan, Kui, et al.
(author)
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Monolithically and Vertically Integrated LED-on-FET Device Based on a Novel GaN Epitaxial Structure
- 2023
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In: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 70:12, s. 6393-6398
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Journal article (peer-reviewed)abstract
- Optoelectronic devices, such as light-emitting diodes (LEDs), based on GaN-based semiconductor compounds are widely used for their advantages of long life, high reliability, and low energy consumption. The persistent challenge is integrating LED with transistors to achieve smaller size, lighter weight, higher speed, and more reliable optoelectronic integrated circuits. Here, we report monolithically and vertically integrated LED-on-FET devices fabricated on a novel GaN epitaxial structure. The designed device structure and fabrication process are simple. It also eliminates the extra area occupied by the transistor, and the shared n-GaN layer between the LED and FET reduces interconnect resistance and improves reliability. The measured threshold voltage (V-Th) of the LED-on-FET device is extrapolated as 3.9 V at the voltage (V-DD) of 5 V, and V-Th decreases with the increase of V-DD . More importantly, the gate voltage (V-GS) shows good performance in modulated electroluminescence (EL) intensity and switching capability of the LED. The integrated LED efficiently emits light modulation with a wavelength of 440 nm at V-DD= 9 V and V-GS=4-9 V (step = 1 V), which are necessary for devices in applications, such as displays and smart lighting. This epitaxy structure and integration scheme is promising in achieving large-scale optoelectronic integrated circuits, such as the next-generation micro-LED and nano-LED with super compact integrated drivers.
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| 4. |
- Tian, Xiaohe, et al.
(author)
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Probe for simultaneous membrane and nucleus labeling in living cells and in vivo bioimaging using a two-photon absorption water-soluble Zn(II) terpyridine complex with a reduced pi-conjugation system
- 2017
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In: Chemical Science. - : ROYAL SOC CHEMISTRY. - 2041-6520 .- 2041-6539. ; 8:1, s. 142-149
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Journal article (peer-reviewed)abstract
- Small, biocompatible and water-soluble molecules with high two-photon absorption (2PA) cross-section values (delta) are in high demand for specific bioimaging applications. Here, two novel terpyridine derivative ligands with donor-acceptor (D-A) (L1) and donor-pi-acceptor (D-pi-A) (L2) models, and their corresponding Zn(II) complexes are designed and characterized. It was found that the two-photon absorption cross section values (d) in the near-infrared region (NIR, about 800 nm) are significantly enhanced for complexes 1 and 2 compared to their free D-A type ligand L1, while those of complexes 3 and 4 were greatly decreased relative to their free ligand L2, thus confirming that the smaller ligand (D-A type) displays a suitable Turn-ON fluorescence pair for two-photon fluorescence microscopy (2PFM). Firstly, the potential of simultaneously labeling a live cell plasma membrane and nucleus using complex 1 is demonstrated. In addition, live larval and adult zebrafish incubated with an optimal concentration of 1 demonstrated clear brain uptake. Lastly and importantly, using such a probe to visualize the blood-brain- barrier (BBB) capillary endothelial cells and penetrate the BBB into the central nervous system (CNS) intravenously in a mouse model is also explored.
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| 5. |
- Wang, Hua, et al.
(author)
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Clamping force integrated computer aided tolerancing in composite assembly
- 2021
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In: Journal of Composite Materials. - : SAGE Publications. - 1530-793X .- 0021-9983. ; 55:10, s. 1405-1417
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Journal article (peer-reviewed)abstract
- Traditional computer aided tolerancing method could not accomplish the tolerancing and variation simulation well in composite assembly. The paper presents a clamping force integrated computer aided tolerancing method for composite assembly. The stochastic variations and the stackup of variations are affected by clamping forces. The clamping force modified probability distribution is used to represent the modification based on the verified FEA model of the composite assembly. The clamping forces are coordinated based on the main deformation mode extracted by the principal component analysis to satisfy the coaxial tolerance requirements of the composite assembly. The assembly of an aircraft composite elevator is considered to illustrate the computational aspects of the proposed methods. The computer aided tolerancing method involving clamping forces outlined in the paper is found to be effective for composite assembly.
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