| 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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- 2019
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Ma, Ruijie, et al.
(författare)
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Adding a Third Component with Reduced Miscibility and Higher LUMO Level Enables Efficient Ternary Organic Solar Cells
- 2020
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 5:8, s. 2711-2720
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Tidskriftsartikel (refereegranskat)abstract
- It is widely known that the miscibility between donor and acceptor is a crucial factor that affects the morphology and thus device performance of nonfullerene organic solar cells (OSCs). In this Letter, we show that incorporating a third component with lower miscibility and higher lowest unoccupied molecular orbital (LUMO) level into the state-of-the-art PM6:Y6 system can significantly enhance the performance of devices. The best results of the ternary devices are achieved by adding a small molecular acceptor named ITCPTC (similar to 5% w/w), which significantly improves the power conversion efficiency (PCE) of the host system from 16.44% to 17.42%. The higher LUMO of the third component increases the open-circuit voltage (V-oc), while the low miscibility enlarges the domains and leads to improved short-circuit current density (J(sc)) and fill factor (FF). The efficacy of this strategy is supported by using other nonfullerene third components including an asymmetric small molecule (N7IT) and a polymer acceptor (PF2-DTC), which play the same role as ITCPTC and boost the PCEs to 16.96% and 17.04%, respectively. Our approach can be potentially applied to a wide range of OSC material systems and should facilitate the development of the OSC field.
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| 4. |
- Miao, Xiujuan, et al.
(författare)
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Aerodynamic performance of a high-speed train passing through three standard tunnel junctions under crosswinds
- 2020
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Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- The aerodynamic performance of a high-speed train passing through tunnel junctions under severe crosswind condition was numerically investigated using improved delayed detached-eddy simulations (IDDES). Three ground scenarios connected with entrances and exits of tunnels were considered. In particular a flat ground, an embankment, and a bridge configuration were used. The numerical method was first validated against experimental data, showing good agreement. The results show that the ground scenario has a large effect on the train's aerodynamic performance. The bridge case resulted in generally smaller drag and lift, as well as a lower pressure coefficient on both the train body and the inner tunnel wall, as compared to the tunnel junctions with flat ground and embankment. Furthermore, the bridge configuration contributed to the smallest pressure variation in time in the tunnel. Overall, the study gives important insights on complicated tunnel junction scenarios coupled with severe flow conditions, that, to the knowledge of the authors, were not studied before. Beside this, the results can be used for further improvements in the design of tunnels where such crosswind conditions may occur.
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| 5. |
- Fan, Qunping, 1989, et al.
(författare)
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High-performance all-polymer solar cells enabled by a novel low bandgap non-fully conjugated polymer acceptor
- 2021
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Ingår i: Science in China Series B. - : Springer Nature. - 1674-7291 .- 1869-1870. ; 64, s. 1380-1388
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Tidskriftsartikel (refereegranskat)abstract
- Anon-fully conjugated polymer as a new class of acceptor materials has shown some advantages over its small molecular counterpart when used in photoactive layers for all-polymer solar cells (all-PSCs), despite a low power conversion efficiency (PCE) caused by its narrow absorption spectra. Herein, a novel non-fully conjugated polymer acceptor PFY-2TS with a low bandgap of similar to 1.40 eV was developed, via polymerizing a large pi-fused small molecule acceptor (SMA) building block (namely YBO) with a non-conjugated thioalkyl linkage. Compared with its precursor YBO, PFY-2TS retains a similar low bandgap but a higher LUMO level. Moreover, compared with the structural analog of YBO-based fully conjugated polymer acceptor PFY-DTC, PFY-2TS shows similar absorption spectrum and electron mobility, but significantly different molecular crystallinity and aggregation properties, which results in optimal blend morphology with a polymer donor PBDB-T and better device physical processes in all-PSCs. As a result, PFY-2TS-based all-PSCs achieved a PCE of 12.31% with a small energy loss of 0.56 eV enabled by the reduced non-radiative energy loss (0.24 eV), which is better than that of 11.08% for the PFY-DTC-based ones. Our work clearly demonstrated that non-fully conjugated polymers as a new class of acceptor materials are very promising for the development of high-performance all-PSCs.
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| 6. |
- He, Kan, et al.
(författare)
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Assessment of LES, IDDES and RANS approaches for prediction of wakes behind notchback road vehicles
- 2021
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 217
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Tidskriftsartikel (refereegranskat)abstract
- The capability of Large Eddy Simulations (LES), Improved Delayed Detached Eddy Simulations (IDDES) and Reynolds-Averaged Navier–Stokes Equations (RANS) to predict the flow behind notchback Ahmed body is investigated in the present paper. Simulations consider two specific models, with effective backlight angles of β1=17.8° and β2=21.0°, respectively. The focus of the study is on the prediction of the expected lateral asymmetry or symmetry of the near-wake flows. Results show that IDDES using coarse computational grids predicts the flow in agreement with LES using finer computational grids. RANS results in inaccurate flow predictions, attributed to its steady formulation relying on turbulence modelling being incapable of dealing with the studied flow. Modal analysis applying Proper Orthogonal Decomposition (POD) suggests the consistency of the wake dynamics between IDDES and LES. The presence of the wake bi-stability is validated by the wind tunnel experiment.
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| 7. |
- He, Kan, 1991, et al.
(författare)
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Blockage influence on bi-stable flows of a notchback bluff body
- 2021
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Ingår i: Physics of Fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 33:12
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Tidskriftsartikel (refereegranskat)abstract
- The expected flow asymmetry behind a three-dimensional notchback Ahmed body is numerically investigated using large-eddy simulations with different blockage ratios of 0%, 5 %, 10 %, and 20 %. The focus of the study is on the natural bi-stable flow influenced by the blockage ratio. Although the wake asymmetry can be observed under the blockage ratio within 0 % - 10 %, the significant blockage influence on the sensitive bi-stability is indicated by the wake structures, pressure gradients, and wake dynamics achieved with the proper orthogonal decomposition. The higher blockage ratio increases the turbulence kinetic energy, velocity, and negative pressure in the near-wake region, resulting in the decrease in the asymmetry degree. The consistency of the asymmetric wake is found with blockage ratios between 0% and 5 %. However, a 20 % blockage ratio symmetrizes the bi-stable wake. Several existing drag corrections for the blockage influence are discussed. The wind tunnel experiment verifies the bi-stable flow with low blockage ratios and the wake symmetrization with a 20 % blockage ratio.
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| 8. |
- He, Kan, et al.
(författare)
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Evaluation of LES, IDDES and URANS for prediction of flow around a streamlined high-speed train
- 2022
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 223
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Tidskriftsartikel (refereegranskat)abstract
- The turbulent flow past a simplified Intercity-Express 3 high-speed train at ReH=6×104 is investigated by a combination of wind tunnel experiments and numerical simulations using the large-eddy simulation (LES), the improved delayed detached eddy simulation (IDDES) and the unsteady Reynolds-averaged Navier-Stokes (URANS) simulation. This work aims to compare the predictive capabilities of LES, IDDES and URANS for the flow over a streamlined high-speed train. Numerical simulations are compared to experimental data for validation. Results show that the well-resolved LES is more accurate among the numerical methods used. Compared to the well-resolved LES, IDDES and URANS using the coarser mesh can produce similar mean flow, although IDDES and URANS are found to be slightly inaccurate for the coherent wake structures near the wall. However, for the near-wall flow instability concerning wake dynamics, Reynolds stresses, turbulence kinetic energy and the fluctuation of pressure, IDDES is found to be inapplicable. Overall, this study suggests that the well-resolved LES is appropriate to the flow of a streamlined high-speed train. Moreover, IDDES and URANS are proved to apply to the mean field of the studied flow.
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| 9. |
- He, Kan, 1991, et al.
(författare)
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Floor motion's influence on wake asymmetry of a notchback bluff body
- 2022
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Ingår i: Physics of Fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 34:3
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Tidskriftsartikel (refereegranskat)abstract
- Large eddy simulations are used to explore the influence of floor motions on asymmetric flows around a notchback bluff body. The focus of this study is on the aerodynamic forces and the extent of natural wake asymmetry presented under moving and stationary ground conditions. The different ground condition has a notable influence on the aerodynamic force and the surrounding pressure distribution of the body. On the other hand, the wake asymmetry, known to be a sensitive phenomenon, is not evidently affected by the floor motion. However, quantitative analysis of the averaged and the statistic flow still suggests slight differences in the degree of wake asymmetry between the two ground conditions. Modal analysis applying proper orthogonal decomposition confirms that the asymmetric wake dynamics and the wake shedding frequency are not sensitive to the floor motion. The accuracy of the numerical simulation is established by a grid-independence study.
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| 10. |
- He, Kan, et al.
(författare)
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Influence of the rounded rear edge on wake bi-stability of a notchback bluff body
- 2021
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Ingår i: Physics of Fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 33:11
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Tidskriftsartikel (refereegranskat)abstract
- The wake bi-stability behind notchback Ahmed bodies is investigated by performing wind tunnel experiments and large eddy simulations (LESs). The focus of this study is on the suppression of bi-stable wakes achieved by rounding the roof's trailing edge of the body. The suppression effect is found to depend on the Reynolds number (R e). The wake behind a sharp edge remains bi-stable for all tested R e. However, for a rounded edge with small radius, wake bi-stability at R e = 0.5 × 10 5 and wake symmetrization with 0.75 × 10 5 ≤ R e ≤ 1.5 × 10 5 are observed. Increasing R e with R e ≥ 1.75 × 10 5, the wake returns to the bi-stable state. Particularly, with R e ≥ 2 × 10 5, a stable asymmetric wake state with no switches is observed for long periods. Performing LES confirms the expected wake asymmetry at R e = 0.5 × 10 5 and symmetry at R e = 1 × 10 5 for the case of rounded edge with a small radius. Besides, another wake symmetry is observed for the rounded edge with a large radius at R e = 0.5 × 10 5. For the two wake symmetries shown in the LES results, the symmetrization is attributed to wake suppression in the notchback region, forcing the flow separation from the rear roof to attach to the slant on both sides of the body.
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