| 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. |
- Li, Youbing, et al.
(författare)
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Electrochemical Lithium Storage Performance of Molten Salt Derived V2SnC MAX Phase
- 2021
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Ingår i: Nano-Micro Letters. - : Springer. - 2311-6706 .- 2150-5551. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- MAX phases are gaining attention as precursors of two-dimensional MXenes that are intensively pursued in applications for electrochemical energy storage. Here, we report the preparation of V2SnC MAX phase by the molten salt method. V2SnC is investigated as a lithium storage anode, showing a high gravimetric capacity of 490 mAh g(-1) and volumetric capacity of 570 mAh cm(-3) as well as superior rate performance of 95 mAh g(-1) (110 mAh cm(-3)) at 50 C, surpassing the ever-reported performance of MAX phase anodes. Supported by operando X-ray diffraction and density functional theory, a charge storage mechanism with dual redox reaction is proposed with a Sn-Li (de)alloying reaction that occurs at the edge sites of V2SnC particles where Sn atoms are exposed to the electrolyte followed by a redox reaction that occurs at V2C layers with Li. This study offers promise of using MAX phases with M-site and A-site elements that are redox active as high-rate lithium storage materials.
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| 3. |
- De Frenne, Pieter, et al.
(författare)
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Biological Flora of the British Isles : Milium effusum
- 2017
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 105:3, s. 839-858
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Tidskriftsartikel (refereegranskat)abstract
- 1. This account presents information on all aspects of the biology of Milium effusum L. (Wood Millet) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation.2. The grass Milium effusum is a common species of mature woodland in central and southern England, but is less common in the wetter parts of northern England, Wales, Scotland and Ireland. Worldwide, the species is native to many temperate, boreal, subarctic and subalpine parts of the northern hemisphere: from eastern North America across most of Europe (excluding Mediterranean climates) to the Ural Mountains and Black Sea, extending eastwards to the Himalaya, Korea and Japan.3. Wood Millet is a shade-tolerant, relatively tall grass (up to 1.8 m) producing up to 700 caryopses per individual. It is characteristic of temperate deciduous woodland, but can also occur in other woodland and forest types and even in scrub, alpine meadows, along railways and roads, and on rocks. In woods, it is one of the most conspicuous plants of the herb layer in the early summer after the disappearance of spring flowering species. While the species is generally considered an ancient woodland indicator in England and western Europe, it is also known to colonize secondary, post-agricultural forests relatively rapidly in other areas such as Denmark, southern Sweden and Poland.4. The species has a wide amplitude in terms of soil acidity and nutrient availability, but predominantly grows on soils of intermediate soil fertility and soil pH and with high organic matter concentration. However, M. effusum can tolerate large quantities of tree-leaf litter on the forest floor and is able to grow on very acidic soils.5. Changes in land use, climate, densities of large herbivores and atmospheric deposition of nitrogen are having effects on populations of Wood Millet. Significant responses of the life-history traits and population characteristics have been detected in response to environmental variation and to experimental treatments of temperature, nutrients, light and acidity. In many of its habitats across its range, M. effusum is currently becoming more frequent. During the last century, its mean elevation of occurrence in upland areas of Europe has also increased by several hundreds of metres. Typically, management actions are directed towards the conservation of its main habitat type (e.g. ancient woodlands of the Milio-Fagetum association) rather than to the species specifically.
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| 4. |
- Gong, Yin, et al.
(författare)
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Insights into evolution of a rift basin : Provenance of the middle Eocene-lower Oligocene strata of the Beibuwan Basin, South China Sea from detrital zircon
- 2021
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Ingår i: Sedimentary Geology. - : Elsevier BV. - 0037-0738 .- 1879-0968. ; 419
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Tidskriftsartikel (refereegranskat)abstract
- Investigating rift basins and their provenance is difficult because their tectonic framework is continuously evolving. The Beibuwan Basin in the South China Sea is a typical rift basin that shares many characteristics of major rift basins worldwide. We present new detrital zircon UPb ages from the Beibuwan basin and, by combining with published data from surrounding drainages, are able to define its potential sources and to investigate its provenance evolution from the middle Eocene-lower Oligocene. Detrital zircon age spectra from distinct structural units and formations of the rift basin reveal spatial-temporal differences in provenance. In the middle-upper Eocene, a similar age pattern with major peaks at 263–253 Ma and 450–416 Ma is preserved across the basin and suggests that sediment was uniformly derived from the Yunkai Massif and Hainan Island. In contrast, during the lower Oligocene the basin displays markedly diverse ages with peaks at 250–243, 416, 756, 967–945, 1096–1084 Ma. The increase of Neoproterozoic zircons in the lower Oligocene stratum suggests that a major change in provenance occurred, most likely associated with the reorganization of the paleo-Pearl River along its central reaches due to a topography reversal associated with the uplift of Tibet and the onset of seafloor spreading in the South China Sea. Our spatial analysis of ages indicates that during the lower Oligocene, the detrital input varied across the basin. Rifting processes in the Beibuwan Basin generated multiple isolated depocenters separated by intra-basinal highs. The basin's architecture greatly affected sediment routing, with structural highs serving as barriers to sediment transport. Sediment provenance in the Beibuwan Basin is primarily controlled by drainage evolution and isolated depocenters associated with an evolving topography, processes which are relevant to the evolution of rift basins globally.
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| 5. |
- Helsen, Kenny, et al.
(författare)
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Impact of an invasive alien plant on litter decomposition along a latitudinal gradient
- 2018
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Ingår i: Ecosphere. - : Wiley. - 2150-8925 .- 2150-8925. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Invasive alien plant effects on ecosystem functions are often difficult to predict across environmental gradients due to the context-dependent interactions between the invader and the recipient communities. Adopting a functional trait-based framework could provide more mechanistic predictions for invasive species' impacts. In this study, we contrast litter decomposition rates among communities with and without the invasive plant Impatiens glandulifera in five regions along a 1600 km long latitudinal gradient in Europe. Across this gradient, four functional traits, namely leaf dry matter content (LDMC), specific leaf area (SLA), stem-specific density (SSD), and plant height, are correlated to rates of litter decomposition of standardized rooibos (labile), green tea (recalcitrant), and I. glandulifera litter. Our results show that both invaded and non-invaded plant communities had a higher expression of acquisitive traits (low LDMC and SSD, high SLA) with increasing temperature along the latitudinal gradient, partly explaining the variation in decomposition rates along the gradient. At the same time, invasion shifted community trait composition toward more acquisitive traits across the latitudinal gradient. These trait changes partly explained the increased litter decomposition rates of the labile litter fraction of rooibos and I. glandulifera litter in invaded communities, a shift that was most evident in the warmer study regions. Plant available nitrogen was lower in invaded communities, likely due to high nutrient uptake by I. glandulifera. Meanwhile, the coldest study region was characterized by a reversed effect of invasion on decomposition rates. Here, community traits related to low litter quality and potential allelopathic effects of the invader resulted in reduced litter decomposition rates, suggesting a threshold temperature at which invader effects on litter decomposition turn positive. This study therefore illustrates how functional trait changes toward acquisitive traits can help explain invader-induced changes in ecosystem functions such as increased litter decomposition.
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| 6. |
- Lei, Chengan, et al.
(författare)
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Controllable dual-polarization valley physics in the strain-engineered 2D monolayer of VC2N4
- 2024
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 12:6, s. 2156-2164
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Tidskriftsartikel (refereegranskat)abstract
- Valley-related physics has garnered significant attention in fundamental studies and cutting-edge information technologies. However, such valleytronic materials have rarely been reported and suffer from in-plane magnetization. Herein, based on first-principles calculations and tight-binding model analysis, we identify the existence of intrinsic valley-contrasting physics in bipolar ferromagnetic monolayer VC2N4 with robust perpendicular magnetic anisotropy behavior. Valley polarization arises spontaneously due to the simultaneous presence of broken space- and time-inversion symmetries. Interestingly, valley polarization is remarkably observed in both the valence and conduction bands around the K/K′ valley due to large spin splitting, indicating rare dual-polarization valley features, which is advantageous for achieving the captivating anomalous valley Hall effect relied on the valley-contrasting Berry curvature. Remarkably, the valley polarization can be switched on/off by applying a moderate biaxial strain. Our work provides a competitive candidate for exploring valley-dependent physics and its applications in valleytronics.
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| 7. |
- Li, Youbing, et al.
(författare)
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Single-Atom-Thick Active Layers Realized in Nanolaminated Ti-3(AlxCu1-x)C-2 and Its Artificial Enzyme Behavior
- 2019
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Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 13:8, s. 9198-9205
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Tidskriftsartikel (refereegranskat)abstract
- A Ti-3(AlxCu1-x)C-2 phase with Cu atoms with a degree of ordering in the A plane is synthesized through the A site replacement reaction in CuCl2 molten salt. The weakly bonded single -atom -thick Cu layers in a Ti-3(AlxCu1-x)C-2 MAX phase provide actives sites for catalysis chemistry. As -synthesized Ti-3(AlxCu1-x)C-2 presents unusual peroxidase-like catalytic activity similar to that of natural enzymes. A fabricated Ti-3(AlxCu1-x)C-2/chitosan/glassy carbon electrode biosensor prototype also exhibits a low detection limit in the electrochemical sensing of H2O2. These results have broad implications for property tailoring in a nanolaminated MAX phase by replacing the A site with late transition elements.
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| 8. |
- Ma, Shiyu, et al.
(författare)
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Local soil characteristics determine the microbial communities under forest understorey plants along a latitudinal gradient
- 2019
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Ingår i: Basic and Applied Ecology. - : Elsevier. - 1439-1791 .- 1618-0089. ; 36, s. 34-44
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Tidskriftsartikel (refereegranskat)abstract
- The soil microbial community is essential for maintaining ecosystem functioning and is intimately linked with the plant community. Yet, little is known on how soil microbial communities in the root zone vary at continental scales within plant species. Here we assess the effects of soil chemistry, large-scale environmental conditions (i.e. temperature, precipitation and nitrogen deposition) and forest land-use history on the soil microbial communities (measured by phospholipid fatty acids) in the root zone of four plant species (Geum urbanum, Milium effusum, Poa nemoralis and Stachys sylvatica) in forests along a 1700km latitudinal gradient in Europe. Soil microbial communities differed significantly among plant species, and soil chemistry was the main determinant of the microbial community composition within each plant species. Influential soil chemical variables for microbial communities were plant species-specific; soil acidity, however, was often an important factor. Large-scale environmental conditions, together with soil chemistry, only explained the microbial community composition in M. effusum and P. nemoralis. Forest land-use history did not affect the soil microbial community composition. Our results underpin the dominant role of soil chemistry in shaping microbial community composition variation within plant species at the continental scale, and provide insights into the composition and functionality of soil microbial communities in forest ecosystems.
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| 9. |
- Ma, Shiyu, et al.
(författare)
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Plant species identity and soil characteristics determine rhizosphere soil bacteria community composition in European temperate forests
- 2019
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press. - 0168-6496 .- 1574-6941. ; 95:6
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Tidskriftsartikel (refereegranskat)abstract
- Soil bacteria and understorey plants interact and drive forest ecosystem functioning. Yet, knowledge about biotic and abiotic factors that affect the composition of the bacterial community in the rhizosphere of understorey plants is largely lacking. Here, we assessed the effects of plant species identity (Milium effusum vs Stachys sylvatica), rhizospheric soil characteristics, large-scale environmental conditions (temperature, precipitation and nitrogen (N) deposition), and land-use history (ancient vs recent forests) on bacterial community composition in rhizosphere soil in temperate forests along a 1700 km latitudinal gradient in Europe. The dominant bacterial phyla in the rhizosphere soil of both plant species were Acidobacteria, Actinobacteria and Proteobacteria. Bacterial community composition differed significantly between the two plant species. Within plant species, soil chemistry was the most important factor determining soil bacterial community composition. More precisely, soil acidity correlated with the presence of multiple phyla, e.g. Acidobacteria (negatively), Chlamydiae (negatively) and Nitrospirae (positively), in both plant species. Large-scale environmental conditions were only important in S. sylvatica and land-use history was not important in either of the plant species. The observed role of understorey plant species identity and rhizosphere soil characteristics in determining soil bacterial community composition extends our understanding of plant-soil bacteria interactions in forest ecosystem functioning.
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