| 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. |
- Yang, Chih-Wen, et al.
(författare)
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Epitaxial Growth and Determination of Band Alignment of Bi2Te3–WSe2 Vertical van der Waals Heterojunctions
- 2020
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Ingår i: ACS Materials Letters. - : American Chemical Society (ACS). - 2639-4979. ; 2:10, s. 1351-1359
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Tidskriftsartikel (refereegranskat)abstract
- Artificial heterojunctions formed by vertical stacking of dissimilar two-dimensional (2D) transition metal dichalcogenide (TMD) monolayer materials in a chosen sequence hold tantalizing prospects for futuristic atomically thin circuits. The emergence of 2D topological insulators (TI), including Bi2Te3, Bi2Se3, and Sb2Te3, represents a new class of 2D building blocks and can complement the existing artificial heterojunctions as a result of their intriguing surface states protected by the time-reversal symmetry. However, the determination of band alignments of such 2D TI/TMD vertical heterojunctions, the key parameter for designing HJ-based electronic/photonic devices, which lies in the development of epitaxy growth, remains in its infancy. Here, we demonstrate the epitaxy growth of 2D TI/TMD vertical heterojunctions comprised of Bi2Te3/WSe2 with atomically clean interfaces that are spectroscopically accessible, and theoretically tractable. Cross-sectional scanning transmission electron microscopy (STEM) images and the presence of interlayer-coupled characteristics from Raman spectroscopy collectively confirm the neat stacking of Bi2Te3/WSe2 with the absence of unwanted containments. Microbeam X-ray photoelectron spectroscopy (ΌXPS) measurement coupled with the density functional theory (DFT) calculations and electrical characteristics of field effect transistors quantitatively reveals the type-II alignment of vertically stacked of quintuple layers (QL) Bi2Te3/WSe2. Meanwhile, the type-III band emerges when transitioning to multi-quintuple layer (MQL) Bi2Te3/WSe2. The finding here provides a well-defined example of the epitaxy growth paradigm, the interlayer coupling-electronic properties relationship, for these emerging 2D TI/TMDs vertical heterojunctions. © 2020 American Chemical Society.
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| 3. |
- Alimena, Juliette, et al.
(författare)
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Searching for long-lived particles beyond the Standard Model at the Large Hadron Collider
- 2020
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 47:9
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Tidskriftsartikel (refereegranskat)abstract
- Particles beyond the Standard Model (SM) can generically have lifetimes that are long compared to SM particles at the weak scale. When produced at experiments such as the Large Hadron Collider (LHC) at CERN, these long-lived particles (LLPs) can decay far from the interaction vertex of the primary proton-proton collision. Such LLP signatures are distinct from those of promptly decaying particles that are targeted by the majority of searches for new physics at the LHC, often requiring customized techniques to identify, for example, significantly displaced decay vertices, tracks with atypical properties, and short track segments. Given their non-standard nature, a comprehensive overview of LLP signatures at the LHC is beneficial to ensure that possible avenues of the discovery of new physics are not overlooked. Here we report on the joint work of a community of theorists and experimentalists with the ATLAS, CMS, and LHCb experiments-as well as those working on dedicated experiments such as MoEDAL, milliQan, MATHUSLA, CODEX-b, and FASER-to survey the current state of LLP searches at the LHC, and to chart a path for the development of LLP searches into the future, both in the upcoming Run 3 and at the high-luminosity LHC. The work is organized around the current and future potential capabilities of LHC experiments to generally discover new LLPs, and takes a signature-based approach to surveying classes of models that give rise to LLPs rather than emphasizing any particular theory motivation. We develop a set of simplified models; assess the coverage of current searches; document known, often unexpected backgrounds; explore the capabilities of proposed detector upgrades; provide recommendations for the presentation of search results; and look towards the newest frontiers, namely high-multiplicity 'dark showers', highlighting opportunities for expanding the LHC reach for these signals.
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