| 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. |
- Abbafati, Cristiana, et al.
(författare)
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- 2020
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Zheng, Xiaopeng, et al.
(författare)
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Managing grains and interfaces via ligand anchoring enables 22.3%-efficiency inverted perovskite solar cells
- 2020
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Ingår i: NATURE ENERGY. - : Nature Publishing Group. - 2058-7546. ; 5, s. 131-140
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Tidskriftsartikel (refereegranskat)abstract
- Inverted perovskite solar cells have attracted increasing attention because they have achieved long operating lifetimes. However, they have exhibited significantly inferior power conversion efficiencies compared to regular perovskite solar cells. Here we reduce this efficiency gap using a trace amount of surface-anchoring alkylamine ligands (AALs) with different chain lengths as grain and interface modifiers. We show that long-chain AALs added to the precursor solution suppress nonradiative carrier recombination and improve the optoelectronic properties of mixed-cation mixed-halide perovskite films. The resulting AAL surface-modified films exhibit a prominent (100) orientation and lower trap-state density as well as enhanced carrier mobilities and diffusion lengths. These translate into a certified stabilized power conversion efficiency of 22.3% (23.0% power conversion efficiency for lab-measured champion devices). The devices operate for over 1,000 h at the maximum power point under simulated AM1.5 illumination, without loss of efficiency. While perovskite solar cells with an inverted architecture hold great promise for operation stability, their power conversion efficiency lags behind that of conventional cells. Here, Zheng et al. achieve a certified 22.34% efficiency, exploiting alkylamine ligands as grain and interface modifiers.
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| 4. |
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| 5. |
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| 6. |
- Fan, Wei, et al.
(författare)
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A review on cutting tool technology in machining of Ni-based superalloys
- 2020
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media Deutschland GmbH. - 0268-3768 .- 1433-3015. ; 110:11-12, s. 2863-2879
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a state-of-the-art review on cutting tool technology in machining of Ni-based superalloys is presented to better understand the current status and to identify future directions of research and development of cutting tool technologies. First, past review articles related to the machining of Ni-based superalloys are summarized. Then machinability of superalloys is introduced, together with the reported methods used in cutting tool design. The current researches on cutting tools in the machining of superalloys are presented in different categories in terms of tool materials, i.e., carbide, ceramics, and Polycrystalline cubic boron nitride (PCBN). Moreover, a set of research issues are identified and highlighted to improve the machining of superalloys. Finally, discussions on the future development are presented, in the areas of new materials/geometries, functional surfaces on the cutting tool, and data-driven comprehensive optimization.
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| 7. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 8. |
- Kim, Jae-Young, et al.
(författare)
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Event Horizon Telescope imaging of the archetypal blazar 3C 279 at an extreme 20 microarcsecond resolution
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 640
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Tidskriftsartikel (refereegranskat)abstract
- 3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique - global Very Long Baseline Interferometry (VLBI) at 1.3mm (230 GHz) - to resolve the innermost jet of 3C 279 in order to study its fine-scale morphology close to the jet base where highly variable-ray emission is thought to originate, according to various models. The source was observed during four days in April 2017 with the Event Horizon Telescope at 230 GHz, including the phased Atacama Large Millimeter/submillimeter Array, at an angular resolution of ∼20 μas (at a redshift of z = 0:536 this corresponds to ∼0:13 pc ∼ 1700 Schwarzschild radii with a black hole mass MBH = 8 × 108 M⊙). Imaging and model-fitting techniques were applied to the data to parameterize the fine-scale source structure and its variation.We find a multicomponent inner jet morphology with the northernmost component elongated perpendicular to the direction of the jet, as imaged at longer wavelengths. The elongated nuclear structure is consistent on all four observing days and across diffierent imaging methods and model-fitting techniques, and therefore appears robust. Owing to its compactness and brightness, we associate the northern nuclear structure as the VLBI "core". This morphology can be interpreted as either a broad resolved jet base or a spatially bent jet.We also find significant day-to-day variations in the closure phases, which appear most pronounced on the triangles with the longest baselines. Our analysis shows that this variation is related to a systematic change of the source structure. Two inner jet components move non-radially at apparent speeds of ∼15 c and ∼20 c (∼1:3 and ∼1:7 μas day-1, respectively), which more strongly supports the scenario of traveling shocks or instabilities in a bent, possibly rotating jet. The observed apparent speeds are also coincident with the 3C 279 large-scale jet kinematics observed at longer (cm) wavelengths, suggesting no significant jet acceleration between the 1.3mm core and the outer jet. The intrinsic brightness temperature of the jet components are ≤1010 K, a magnitude or more lower than typical values seen at ≥7mm wavelengths. The low brightness temperature and morphological complexity suggest that the core region of 3C 279 becomes optically thin at short (mm) wavelengths.
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| 9. |
- Li, Guoqiang, et al.
(författare)
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Differential ice volume and orbital modulation of Quaternary moisture patterns between Central and East Asia
- 2020
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Ingår i: Earth and Planetary Science Letters. - : Elsevier. - 0012-821X .- 1385-013X. ; 530
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Tidskriftsartikel (refereegranskat)abstract
- Desertification is of pressing environmental concern in large parts of Asia and directly affects millions of people. Arid Central Asia (ACA) in particular is highly sensitive to desertification and environmental change. Climate change in ACA may be driven by westerly circulation or monsoon variation. However, no consensus exists over their relative importance during the Quaternary and this greatly restricts our understanding of how this region may be affected by future climate change. Here we use the most detailed luminescence dating age model yet produced for ACA for three loess records in the Tianshan Mountains spanning the past 250 ka to show a sharp dichotomy in moisture variation between lowland and high mountain areas. The lowland areas of ACA are subjected to persistent aridity during past 250 ka, while highland areas clearly show dry-glacial and moist-interglacial changes, synchronous to moisture variability in monsoonal East Asia, and both co-varying with global ice volume and greenhouse gas (GHG) variation. In contrast, moisture variability across ACA within interglacials varies inversely with insolation-driven precessional changes. This is directly out of phase with the moisture changes of East Asia, which co-vary with precessional insolation changes, and indicates the influence of Westerly circulation in ACA. Our Flexible Global Ocean-Atmosphere-Land System model simulations further reveal that coupled ice volume and GHG variations dominated climatic variability in both ACA and East Asia over glacial-interglacial cycles. However, the out of phase relationship between the intensity of the Westerly and East Asian monsoon systems during interglacial periods indicates that precessional forcing is responsible for differences in moisture patterns between ACA and East Asia. These observations indicate that moisture levels will not increase even in high altitude regions of ACA over the next several millennia; rather desertification is likely to worsen resulting from stabilization of the Westerlies as a result of low summer insolation.
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| 10. |
- Lu, Yingchang, et al.
(författare)
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Identification of Novel Loci and New Risk Variant in Known Loci for Colorectal Cancer Risk in East Asians
- 2020
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Ingår i: Cancer Epidemiology, Biomarkers and Prevention. - : American Association for Cancer Research. - 1055-9965 .- 1538-7755. ; 29:2, s. 477-486
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Tidskriftsartikel (refereegranskat)abstract
- Background: Risk variants identified so far for colorectal cancer explain only a small proportion of milial risk of this cancer, particularly in Asians.Methods: We performed a genome-wide association study (GWAS) of colorectal cancer in East Asians, cluding 23,572 colorectal cancer cases and 48,700 controls. To identify novel risk loci, we selected 60 omising risk variants for replication using data from 58,131 colorectal cancer cases and 67,347 controls European descent. To identify additional risk variants in known colorectal cancer loci, we performed nditional analyses in East Asians.Results: An indel variant, rs67052019 at 1p13.3, was found to be associated with colorectal cancer risk P = 3.9 x 10(-8) in Asians (OR per allele deletion = 1.13, 95% confidence interval = 1.08-1.18). This sociation was replicated in European descendants using a variant (rs2938616) in complete linkage sequilibrium with rs67052019 (P = 7.7 x 10(-3)). Of the remaining 59 variants, 12 showed an association P < 0.05 in the European-ancestry study, including rs11108175 and rs9634162 at P < 5 x 10(-8) and o variants with an association near the genome-wide significance level (rs60911071, P = 5.8 x 10(-8); 62558833, P = 7.5 x 10(-8)) in the combined analyses of Asian- and European-ancestry data. In addition, ing data from East Asians, we identified 13 new risk variants at 11 loci reported from previous GWAS.Conclusions: In this large GWAS, we identified three novel risk loci and two highly suggestive loci for lorectal cancer risk and provided evidence for potential roles of multiple genes and pathways in the iology of colorectal cancer. In addition, we showed that additional risk variants exist in many colorectal ncer risk loci identified previously.Impact: Our study provides novel data to improve the understanding of the genetic basis for colorectal ncer risk.
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