| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)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. |
- Jian, Jingxin, et al.
(författare)
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Cubic SiC Photoanode Coupling with Ni:FeOOH Oxygen-Evolution Cocatalyst for Sustainable Photoelectrochemical Water Oxidation
- 2020
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Ingår i: Solar RRL. - : WILEY-V C H VERLAG GMBH. - 2367-198X. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- As an efficient water oxidation cocatalyst, the Earth-abundant nickel-iron oxyhydroxide (Ni:FeOOH) is introduced to coat on the cubic silicon carbide (3C-SiC) photoanode surface for improving the photoelectrochemical (PEC) water oxidation performance. The FeOOH is prepared on the 3C-SiC photoanode surface by hydrothermal deposition, followed by a photoassisted electrodeposition of NiOOH. It is shown that the Ni:FeOOH layer is composed of the beta-FeOOH nanorods with a conformal coating of the amorphous NiOOH. Under AM1.5G 100 mW cm(-2) illumination, the 3C-SiC/Ni:FeOOH photoanode exhibits a very low onset potential of 0.2 V versus reversible hydrogen electrode (V-RHE) and a high photocurrent density of 1.15 mA cm(-2) at 1.23 V-RHE, distinctly outperforming the 3C-SiC and the 3C-SiC/FeOOH counterparts. Open-circuit potential and impedance spectroscopy results demonstrate that the nanostructured Ni:FeOOH layer on the 3C-SiC surface increases the photovoltage and promotes the charge transfer toward the electrolyte, thus significantly improving the PEC water-splitting performance. These results provide new insights for the development of photoanodes toward efficient solar-fuel generation.
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| 3. |
- Li, Hao, et al.
(författare)
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Atomic-Scale Tuning of Graphene/Cubic SiC Schottky Junction for Stable Low-Bias Photoelectrochemical Solar-to-Fuel Conversion
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 14:4, s. 4905-4915
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Tidskriftsartikel (refereegranskat)abstract
- Engineering tunable graphene-semiconductor interfaces while simultaneously preserving the superior properties of graphene is critical to graphene-based devices for electronic, optoelectronic, biomedical, and photoelectrochemical applications. Here, we demonstrate this challenge can be surmounted by constructing an interesting atomic Schottky junction via epitaxial growth of high-quality and uniform graphene on cubic SiC (3C-SiC). By tailoring the graphene layers, the junction structure described herein exhibits an atomic-scale tunable Schottky junction with an inherent built-in electric field, making it a perfect prototype to systematically comprehend interfacial electronic properties and transport mechanisms. As a proof-of-concept study, the atomic-scale-tuned Schottky junction is demonstrated to promote both the separation and transport of charge carriers in a typical photoelectrochemical system for solar-to-fuel conversion under low bias. Simultaneously, the as-grown monolayer graphene with an extremely high conductivity protects the surface of 3C-SiC from photocorrosion and energetically delivers charge carriers to the loaded cocatalyst, achieving a synergetic enhancement of the catalytic stability and efficiency.
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| 4. |
- Shi, Yuchen, et al.
(författare)
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A patterning-free approach for growth of free-standing graphene nanoribbons using step-bunched facets of off-oriented 4H-SiC(0 0 0 1) epilayers
- 2020
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 53:11
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Tidskriftsartikel (refereegranskat)abstract
- The tunable electronic structure of graphene nanoribbons (GNRs) has attracted much attention due to the great potential in nanoscale electronic applications. Most methods to produce GNRs rely on the lithographic process, which suffers from the process-induced disorder in the graphene and scalability issues. Here, we demonstrate a novel approach to directly grow free-standing GNRs on step-bunched facets of off-oriented 4H-SiC epilayers without any patterning or lithography. First, the 4H-SiC epilayers with well-defined bunched steps were intentionally grown on 4 degree off-axis 4H-SiC substrates by the sublimation epitaxy technique. As a result, periodic step facets in-between SiC terraces were obtained. Then, graphene layers were grown on such step-structured 4H-SiC epilayers by thermal decomposition of SiC. Scanning tunneling microscopy (STM) studies reveal that the inclined step facets are about 13-15 nm high and 30-35 nm wide, which gives an incline angle of 23-25 degrees. LEEM and LEED results showed that the terraces are mainly covered by monolayer graphene and the buffer layer underneath it. STM images and the analysis of their Fourier transform patterns suggest that on the facets, in-between terraces, graphene is strongly buckled and appears to be largely decoupled from the surface.
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| 5. |
- Shi, Yuchen, et al.
(författare)
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Epitaxial Graphene Growth on the Step-Structured Surface of Off-Axis C-Face 3C-SiC(1¯1¯1¯)
- 2020
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Ingår i: Physica Status Solidi (B) Basic Research. - : Wiley. - 0370-1972 .- 1521-3951. ; 257:6
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Tidskriftsartikel (refereegranskat)abstract
- Graphene layers grown on the C-face SiC exhibit quite different structural and electronic properties compared with those grown on the Si-face SiC. Herein, the growth and structural properties of graphene on the off-axis C-face 3C-SiC((Formula presented.)) are studied. The as-grown 4° off-axis 3C-SiC((Formula presented.)) exhibits highly periodic steps with step height of ≈0.75 nm and terrace width of ≈50 nm. After annealing at 1800 °C under 850 mbar argon atmosphere, relatively uniform large graphene domains can be grown. The low-energy electron microscopy (LEEM) results demonstrate that one monolayer (ML) to four-ML graphene domains are grown over several micrometers square, which enables us to measure micro low-energy electron diffraction (μ-LEED) on the single graphene domain. The μ-LEED pattern collected on the monolayer domain mainly exhibits four sets of graphene (1 × 1) spots, indicating the presence of graphene grains with different azimuthal orientations in the same graphene sheet. Raman spectra collected on the graphene domains show rather small D peaks, indicating the presence of less defects and higher crystalline quality of the graphene layers grown on the C-face off-axis 3C-SiC((Formula presented.)).
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