| 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. |
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| 3. |
- Li, Lili, et al.
(författare)
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UV-protection and fluorescence properties of the exoskeleton obtained from a living diatom modified by an Eu3+-complex
- 2021
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 9:31, s. 10005-10012
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Tidskriftsartikel (refereegranskat)abstract
- In this article, a natural biological porous material, from living diatoms, is used to prepare new UV-protection hybrid materials with an Eu3+-complex. By removing the organic protoplasm of living diatoms, the exoskeleton with a regular pore structure arrangement was obtained. The Eu3+-complex was chemically bonded to the exoskeleton modified by the silane coupling agent (3-aminopropyl)trimethoxy silane (APTMS). Compared with pure Eu3+-complexes, the fluorescence intensity of this hybrid material was increased by approximately 10 times. For illustrating its applications in the field of UV-protection, we mixed the USDU with polyacrylonitrile to produce flexible and transparent polymer films. The hybrid composite film (USDU@PAN) achieved partial absorption of ultraviolet light between 200 and 400 nm. At the same time, it also emits visible fluorescence and the intensity of the fluorescence is greatly increased. Therefore, the USDU@PAN film has wide application prospects in areas such as photoelectric sensors and UV-protection devices. More importantly, we transform natural organisms into materials with excellent optical properties. Therefore, it can be used in the field of UV-protection.
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| 4. |
- Stahl, Adam, 1985, et al.
(författare)
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Eddington capture sphere around luminous stars
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 546:10
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Tidskriftsartikel (refereegranskat)abstract
- Test particles infalling from infinity onto a compact spherical star with a mildly super-Eddington luminosity at its surface are typically trapped on the “Eddington capture sphere” and do not reach the surface of the star. The presence of a sphere on which radiation pressure balances gravity for static particles was first discovered some twenty five years ago. Subsequently, it was shown to be a capture sphere for particles in radial motion, and more recently also for particles in non-radial motion, in which the Poynting-Robertson radiation drag efficiently removes the orbital angular momentum of the particles, reducing it to zero. Here we develop this idea further, showing that “levitation” on the Eddington sphere (above the stellar surface) is a state of stable equilibrium, and discuss its implications for Hoyle-Lyttleton accretion onto a luminous star. When the Eddington sphere is present, the cross-section of a compact star for actual accretion is typically less than the geometrical cross-section πR2, direct infall onto the stellar surface only being possible for relativistic particles, with the required minimum particle velocity at infinity typically about half the speed of light. We further show that particles on typical trajectories in the vicinity of the stellar surface will also be trapped on the Eddington capture sphere.
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| 5. |
- Watts, Anna L., et al.
(författare)
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Dense matter with eXTP
- 2019
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Ingår i: Science China Physics, Mechanics & Astronomy. - : Science Press. - 1674-7348 .- 1869-1927. ; 62:2
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Forskningsöversikt (refereegranskat)abstract
- In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is expected to be launched in the mid 2020s.
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| 6. |
- Yu, Xiaoshuang, et al.
(författare)
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Organic Eu3+-complex-anchored porous diatomite channels enable UV protection and down conversion in hybrid material
- 2020
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Ingår i: Science and Technology of Advanced Materials. - : TAYLOR & FRANCIS LTD. - 1468-6996 .- 1878-5514. ; 21:1, s. 726-736
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Tidskriftsartikel (refereegranskat)abstract
- The organic Eu3+-complex [Eu(TTA)(3)Phen] has been incorporated into the channels of surface-modified frustules from diatoms as a key material to absorb and convert UV-photons to visible luminescence. Systematic investigation results indicate that the organic Eu3+-complex encapsulated in the functionalized diatomite channels exhibits enhanced luminescence and longer lifetime, owning to the Eu(TTA)(3)Phen complex interacting with its surrounding silylating agents. The organic Eu3+-complex-anchored porous diatomite hybrid luminescent material was compounded with polyethylene terephthalate (PET) by using a mini-twin screw extruder to prepare a self-supporting film of the hybrid material. Besides, the UV absorption properties of the composite films were investigated. These films will potentially be related to the UV protection of photovoltaic devices.
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| 7. |
- Zhang, Yu, et al.
(författare)
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Comparative phylogenomics and phylotranscriptomics provide insights into the genetic complexity of nitrogen-fixing root-nodule symbiosis
- 2024
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Ingår i: Plant communications. - 2590-3462. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Plant root-nodule symbiosis (RNS) with mutualistic nitrogen-fixing bacteria is restricted to a single clade of angiosperms, the Nitrogen-Fixing Nodulation Clade (NFNC), and is best understood in the legume family. Nodulating species share many commonalities, explained either by divergence from a common ancestor over 100 million years ago or by convergence following independent origins over that same time period. Regardless, comparative analyses of diverse nodulation syndromes can provide insights into constraints on nodulation-what must be acquired or cannot be lost for a functional symbiosis-and the latitude for variation in the symbiosis. However, much remains to be learned about nodulation, especially outside of legumes. Here, we employed a large-scale phylogenomic analysis across 88 species, complemented by 151 RNA-seq libraries, to elucidate the evolution of RNS. Our phylogenomic analyses further emphasize the uniqueness of the transcription factor NIN as a master regulator of nodulation and identify key mutations that affect its function across the NFNC. Comparative transcriptomic assessment revealed nodulespecific upregulated genes across diverse nodulating plants, while also identifying nodule-specific and nitrogen-response genes. Approximately 70% of symbiosis-related genes are highly conserved in the four representative species, whereas defense-related and host-range restriction genes tend to be lineage specific. Our study also identified over 900 000 conserved non-coding elements (CNEs), over 300 000 of which are unique to sampled NFNC species. NFNC-specific CNEs are enriched with the active H3K9ac mark and are correlated with accessible chromatin regions, thus representing a pool of candidate regulatory elements for genes involved in RNS. Collectively, our results provide novel insights into the evolution of nodulation and lay a foundation for engineering of RNS traits in agriculturally important crops.
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