| 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. |
- Lin, Ci, et al.
(författare)
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Direct Band Gap in Multilayer Transition Metal Dichalcogenide Nanoscrolls with Enhanced Photoluminescence
- 2022
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Ingår i: ACS Materials Letters. - : American Chemical Society (ACS). - 2639-4979. ; 4:8, s. 1547-1555
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Tidskriftsartikel (refereegranskat)abstract
- A direct band gap that solely exists in monolayer semiconducting transition metal dichalcogenides (TMDs) endows strong photoluminescence (PL) features, whereas multilayer TMD structures exhibit quenched PL due to the direct-to-indirect band gap transition. We demonstrate multi-layer TMD (such as MoS2 and WS2) nanoscrolls with a preserved direct band gap fabricated by an effective and facile method of solvent-driven self-assembly. The resultant multi-layer nanoscrolls, exhibiting up to 11 times higher PL intensity than the remanent monolayer, are carefully characterized using PL spectroscopy. Significantly enlarged interlayer distances and modulated interlayer coupling in the fabricated nanostructures are unveiled by cross-sectional scanning transmission electron microscopy, atomic force microscopy, and Raman spectroscopy. The preservation of direct band gap features is further evidenced by density functional theory calculations using the simplified bilayer model with an experimentally obtained 15 & ANGS; interlayer distance. The modulation of the PL intensity as an indicator of the band gap crossover in the TMD nanoscrolls is demonstrated by removing the acetone molecules trapped inside the interlayer space. The general applicability of the method presents an opportunity for large-scale fabrication of a plethora of multilayer TMD nanoscrolls with direct band gaps.
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| 3. |
- Wang, Ci, et al.
(författare)
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Twinning pathways in Fe and Fe-Cr alloys from first-principles theory
- 2021
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 215
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Tidskriftsartikel (refereegranskat)abstract
- Using density-functional theory, we determine the generalized stacking fault energy (GSFE) for the {1 (1) over bar 12} < 1 (1) over bar 11 > twinning system in ferromagnetic (FM) body-centered cubic Fe and Fe-Cr alloys with molar fraction of Cr <= 0.5. We adopt both reflection and isosceles twinning pathways and reveal the magnetic ordering effects on the GSFE by contrasting the FM results to those obtained for the magnetically disordered paramagnetic (PM) state. The results show that the isosceles twin boundary configuration is energetically preferred in this binary. The loss of long-range magnetic order lowers the GSFE amplitude but increases the twin boundary migration (TBM) energy regardless of the Cr content. The twin boundary formation (TBF) energy and the TBM energy show non-linear dependences on Cr content in the FM and PM states, and the effect of Cr on these properties critically depends on the magnetic state. We discuss our results in regard to the stable twin boundary structure and deformation twinning experimentally observed in homogeneous Fe-50 wt.% Cr alloy up to temperatures slightly above the magnetic ordering temperature.
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| 4. |
- Yang, Yaochun, et al.
(författare)
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Corrigendum to “First-principles study of the Σ3(112) grain boundary in Fe-rich Fe-Cr alloys” [Scripta Materialia 181 (2020) 140-143] (Scripta Materialia (2020) 140-143 (S1359646220301056), (10.1016/j.scriptamat.2020.02.029))
- 2021
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 191, s. 202-203
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Tidskriftsartikel (refereegranskat)abstract
- The authors regret that in producing Figs. 1 and 2, and Table S1 in our article an inadvertent error was made when calculating the bulk reference energy using an incorrect lattice setting. The bulk reference energy was recalculated using the correct lattice setting. Correction of the error results in a systematic shift in the grain boundary (GB) energies towards higher energies; see the corrected figures and table below. The change weakens the effect of Cr on the GB energy of chemically homogenous Fe1-xCrx alloys as shown in Fig. 1 (squares, red line), but doesn't influence the trends for chemically inhomogeneous Fe1-xCrx alloys as shown in Fig. 2 and Table S1. The correction has no effect on the analysis of the results and the conclusions presented in the original paper. The authors would like to apologise for any inconvenience caused.
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| 5. |
- Yang, Yaochun, et al.
(författare)
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First-principles study of the Σ3(112) grain boundary in Fe-rich Fe-Cr alloys
- 2020
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 181, s. 140-143
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Tidskriftsartikel (refereegranskat)abstract
- We report a first-principles investigation of the Sigma 3(112) grain boundary (GB) in body-centered cubic Fe-rich Fe1-xCrx alloy as a function of chemical composition and temperature. The equilibrium amount of Cr at the GB undergoes a sharp transition from slight enrichment in low-alloyed Fe-Cr (x <= 0.06-0.08) to complete Cr saturation for 0.08 <= x <= 0.15. The GB chemistry at room-temperature and below is characterized by miscibility gaps, destabilizing a Fe-Cr interfacial solid solution towards decomposition into Fe-rich and Cr-rich clusters. The Cr-rich clusters at the GB may serve as nucleation centers for secondary phases in Fe-Cr alloys.
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