| 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. |
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| 4. |
- Dang, D. F., et al.
(författare)
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Manipulating backbone structure with various conjugated spacers to enhance photovoltaic performance of D-A-type two-dimensional copolymerse
- 2014
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Ingår i: Organic Electronics: physics, materials, applications. - : Elsevier BV. - 1566-1199. ; 15:11, s. 2876-2884
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Tidskriftsartikel (refereegranskat)abstract
- A class of low band-gap two-dimensional conjugated polymers of PBDTT-FQ PBDTT-TQ PBDTT-BTQ and PBDTT-TTQ was designed and synthesized, which contains the same di(alkylthiophene)-substituted benzo[1,2-b:4,5-b']dithiophene (BDTT) and 6,7-difluoro-quinoxaline (Q) units, as well as various conjugated spacers of furan, thiophene, bithiophene and thieno[3,2-b]thiophene in the main chain. Significant effect of the varied spacers between the BDTT and Q units on the thermal, optical, electrochemical and photovoltaic properties was investigated and observed for these two-dimensional copolymers in the polymer solar cells. The maximum power conversion efficiency of 5.9% with a short circuit current of 13.7 mA/cm(2) and a fill factor of 0.56 was obtained for the PBDTT-TQ with thiophene spacer in the bulk hetero-junction PSCs using [6,6]-phenyl-C-71-butyric acid methyl ester as acceptor.
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| 5. |
- Su, Wenyan, et al.
(författare)
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13.4 % Efficiency from All-Small-Molecule Organic Solar Cells Based on a Crystalline Donor with Chlorine and Trialkylsilyl Substitutions
- 2021
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 14:17, s. 3535-3543
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Tidskriftsartikel (refereegranskat)abstract
- How to simultaneously achieve both high open-circuit voltage (Voc) and high short-circuit current density (Jsc) is a big challenge for realising high power conversion efficiency (PCE) in all-small-molecule organic solar cells (all-SM OSCs). Herein, a novel small molecule (SM)-donor, namely FYSM−SiCl, with trialkylsilyl and chlorine substitutions was designed and synthesized. Compared to the original SM-donor FYSM−H, FYSM−Si with trialkylsilyl substitution showed a decreased crystallinity and lower highest occupied molecular orbital (HOMO) level, while FYSM−SiCl had an improved crystallinity, more ordered packing arrangement, significantly lower HOMO level, and predominant “face-on” orientation. Matched with a SM-acceptor Y6, the FYSM−SiCl-based all-SM OSCs exhibited both high Voc of 0.85 V and high Jsc of 23.7 mA cm−2, which is rare for all-SM OSCs and could be attributed to the low HOMO level of FYSM−SiCl donor and the delicate balance between high crystallinity and suitable blend morphology. As a result, FYSM−SiCl achieved a high PCE of 13.4 % in all-SM OSCs, which was much higher than those of the FYSM−H- (10.9 %) and FYSM−Si-based devices (12.2 %). This work demonstrated a promising method for the design of efficient SM-donors by a side-chain engineering strategy via the introduction of trialkylsilyl and chlorine substitutions.
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| 6. |
- Wang, Tingsong, et al.
(författare)
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A two-stage stochastic nonlinear integer-programming model for slot allocation of a liner container shipping service
- 2021
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Ingår i: Transportation Research Part B: Methodological. - : Elsevier BV. - 0191-2615. ; 150, s. 143-160
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we propose a container slot allocation problem for a liner shipping service. A liner containership provides a regular shipping service with a fixed itinerary and schedule. In practice, the liner containership may not be fully loaded, which results in a loss of revenue. We therefore segment shippers into two classes: contract shippers and spot shippers. A contract shipper has a contract with the shipping company and negotiates a fixed minimum quantity, so that the shipping company can secure a steady revenue. The remaining containership slots are open to spot shippers, allowing the shipping company to obtain ad hoc revenue. The container slot allocation problem is investigated in this study using a two-stage stochastic mixed-integer nonlinear programming model. We use the sample average approximation based on Lagrangian relaxation and dual decomposition techniques to effectively solve the model. Finally, we conduct a case study to evaluate the applicability and effectiveness of the proposed model and the solution algorithm.
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| 7. |
- Wu, Keming, et al.
(författare)
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Surface Reconstruction on Uniform Cu Nanodisks Boosted Electrochemical Nitrate Reduction to Ammonia
- 2022
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Ingår i: ACS Materials Letters. - : American Chemical Society (ACS). - 2639-4979. ; 4, s. 650-656
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Tidskriftsartikel (refereegranskat)abstract
- The Haber-Bosch (HB) process has provided most of commercial ammonia at the expense of high energy consumption and high CO2 emission. Nitrate electroreduction is showing great potential as an alternative route for the green and scale-up synthesis of ammonia at ambient conditions. However, the performance has lagged due to lack of efficient electrocatalysts. In this work, we present the facile synthesis of uniform Cu nanodisks with exposed (111) facets as highly active electrocatalyst for electrochemical ammonia synthesis, delivering a high ammonia yield of 2.16 mg mg-1cat h-1 and a maximum Faradaic efficiency of 81.1% at -0.5 V versus a reversible hydrogen electrode (RHE). The remarkable activity is originated from the surface reconstructed triatomic Cu clusters due to the cathodic deoxygenation process. As a result, the reconstructed surface shows enhanced affinity to the adsorption of nitrate ions which undergo successive break of three N-O bonds, followed by subsequent formation of three N-H bonds to finally form NH3. The present study provides the feasible preparation of Cu based advanced catalysts and a unique insight into the mechanism of nitrate electroreduction.
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| 8. |
- Zhuang, Wenliu, 1979, et al.
(författare)
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Synthesis and Electronic Properties of Diketopyrrolopyrrole-Based Polymers with and without Ring-Fusion
- 2021
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 54:2, s. 970-980
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Tidskriftsartikel (refereegranskat)abstract
- Diketopyrrolopyrroles (DPP) have been recognized as a promising acceptor unit for construction of semiconducting donor-acceptor (D-A) polymers, which are typically flanked by spacers such as thiophene rings via a carbon-carbon single bond formation. It may suffer from a decrease in the coplanarity of the molecules especially when bulky side chains are installed. In this work, the two N atoms in the DPP unit are further fused with C-3 of the two flanking thiophene rings, yielding a p-expanded, very planar fused-ring building block (DPPFu). A novel DPPFu-based D-A copolymer (PBDTT-DPPFu) was successfully synthesized, consisting of a benzo[1,2-b:4,5-b]dithiophene (BDTT) unit as a donor and a DPPFu unit as an acceptor. For comparison, the unfused DPP-based counterpart PBDTT-DPP was also synthesized. Two dodecyl alkyl chains were attached to thiophene rings of DPP moieties to ensure good solubility of the DPPFu-based polymer. The influence of the ring-fusion effect on their structure, photophysical properties, electronic properties, molecular packing, and charge transport properties is investigated. Ring-fusion enhances the intermolecular interactions of PBDTT-DPPFu polymer chains as indicated by density functional theory calculation and analysis of electrostatic potential and van der Waals potential and results in significantly improved molecular packing for both the in-plane and out-of-plane directions as suggested by X-ray measurements. Finally, we correlate the molecular packing to the device performance by fabricating field-effect transistors based on these two polymers. The charge carrier mobility of the ring-fused polymer PBDTT-DPPFu is significantly higher as compared to the PBDTT-DPP polymer without ring-fusion, although PBDTT-DPPFu exhibited a much lower number-average molecular weight of 17 kDa as compared to PBDTT-DPP with a molecular weight of 108 kDa. The results from our comparative study provide a robust way to increase the interchain interaction by ring-fusion-promoted coplanarity.
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| 9. |
- Algaba, Juan-Carlos, et al.
(författare)
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Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign
- 2021
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
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Forskningsöversikt (refereegranskat)abstract
- In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
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| 10. |
- Chen, Qiang, et al.
(författare)
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Transient Relativistic Plasma Grating to Tailor High-Power Laser Fields, Wakefield Plasma Waves, and Electron Injection
- 2022
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 128:16
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Tidskriftsartikel (refereegranskat)abstract
- We show the first experiment of a transverse laser interference for electron injection into the laser plasma accelerators. Simulations show such an injection is different from previous methods, as electrons are trapped into later acceleration buckets other than the leading ones. With optimal plasma tapering, the dephasing limit of such unprecedented electron beams could be potentially increased by an order of magnitude. In simulations, the interference drives a relativistic plasma grating, which triggers the splitting of relativistic-intensity laser pulses and wakefield. Consequently, spatially dual electron beams are accelerated, as also confirmed by the experiment.
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