| 1. |
- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)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. |
- Wang, Ning, et al.
(author)
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Boride-derived oxygen-evolution catalysts
- 2021
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In: Nature Communications. - : Springer Nature. - 2041-1723. ; 12
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Journal article (peer-reviewed)abstract
- Metal borides/borates have been considered promising as oxygen evolution reaction catalysts; however, to date, there is a dearth of evidence of long-term stability at practical current densities. Here we report a phase composition modulation approach to fabricate effective borides/borates-based catalysts. We find that metal borides in-situ formed metal borates are responsible for their high activity. This knowledge prompts us to synthesize NiFe-Boride, and to use it as a templating precursor to form an active NiFe-Borate catalyst. This boride-derived oxide catalyzes oxygen evolution with an overpotential of 167 mV at 10 mA/cm2 in 1 M KOH electrolyte and requires a record-low overpotential of 460 mV to maintain water splitting performance for over 400 h at current density of 1 A/cm2. We couple the catalyst with CO reduction in an alkaline membrane electrode assembly electrolyser, reporting stable C2H4 electrosynthesis at current density 200 mA/cm2 for over 80 h.
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| 3. |
- Chen, Nai-Chen, 1985-, et al.
(author)
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Controlling factors on patterns of dissolved organic carbon and volatile fatty acids in a submarine mud volcano offshore southwestern Taiwan
- 2023
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In: Frontiers in Earth Science. - 2296-6463. ; 11
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Journal article (peer-reviewed)abstract
- Dissolved organic carbon (DOC) and volatile fatty acids (VFAs) play key roles in the carbon cycling of marine sediment. Both microbially or thermally activated cracking of organic matter often produces high quantities of DOC and VFAs. To uncover the distribution pattern of DOC and VFAs in sediments under both impacts, a submarine mud volcano (SMV), was chosen to denote a model system that could witness how microbial activities react under the mixing of seawater and deeply-sourced fluids in a subsurface environment. We examined the concentration profiles of DOC and several VFAs (lactate, formate, acetate, propionate, and butyrate) in pore water, covering both sulfate reduction and methanogenesis zones, and further numerically modeled six porewater species (DOC, bromide, calcium, magnesium, ammonium, and total alkalinity) to quantify their fluxes from depth as well as the rates of in-situ microbial processes. Apparently, bulk DOC concentrations fluctuated with depths, probably primarily controlled by in situ microbial processes. Lactate was detectable in some samples, while propionate and butyrate were under detection limit. Acetate and formate concentrations were consistently and uniformly low throughout all biogeochemical zones, with a slightly increasing trend with depth at the center of the SMV, suggesting active utilization and turnover by the terminal steps of organic matter mineralization. The numerical modeling suggests that most DOC patterns were primarily influenced by in-situ organic matter degradation, while the impact of upward migrating fluid become more significant at center sites. The calculation of the Gibbs energy of metabolic redox reactions reveals that acetoclastic sulfate reduction yields the highest energy throughout sediment columns and may co-exist with methanogenesis below sulfate reduction zone. In contrast, acetoclastic methanogenesis yields higher energy within sulfate reduction zone than below that region, suggesting it is thermodynamically feasible to co-occur with sulfate reduction in dynamic SMV environments.
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| 4. |
- Lin, Lien-Hsuan, et al.
(author)
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HYDRODYNAMICAL SIMULATIONS OF THE BARRED SPIRAL GALAXY NGC 1097
- 2013
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In: Astrophysical Journal. - 0004-637X. ; 771:1
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Journal article (peer-reviewed)abstract
- NGC 1097 is a nearby barred spiral galaxy believed to be interacting with the elliptical galaxy NGC 1097A located to its northwest. It hosts a Seyfert 1 nucleus surrounded by a circumnuclear starburst ring. Two straight dust lanes connected to the ring extend almost continuously out to the bar. The other ends of the dust lanes attach to two main spiral arms. To provide a physical understanding of its structural and kinematical properties, two-dimensional hydrodynamical simulations have been carried out. Numerical calculations reveal that many features of the gas morphology and kinematics can be reproduced provided that the gas flow is governed by a gravitational potential associated with a slowly rotating strong bar. By including the self-gravity of the gas disk in our calculation, we have found the starburst ring to be gravitationally unstable, which is consistent with the observation in Hsieh et al. Our simulations show that the gas inflow rate is 0.17 M-circle dot yr(-1) into the region within the starburst ring even after its formation, leading to the coexistence of both a nuclear ring and a circumnuclear disk.
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| 5. |
- Wu, Liang-Ting, et al.
(author)
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Role of copper as current collectors in the reductive reactivity of polymers for anode-free lithium metal batteries : Insights from DFT and AIMD studies
- 2023
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In: Materials Today Physics. - : Elsevier. - 2542-5293. ; 38
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Journal article (peer-reviewed)abstract
- Understanding the role of current collectors (CCs) in the reductive reactivity of polymers on Li metal and the resultant solid electrolyte interphase (SEI) formation is essential for improving the performance of anode-free lithium metal batteries (AFLMBs). In this study, we have examined the reactivity of three polymeric hosts: poly(ethylene oxide) (PEO), poly(epsilon-caprolactone) (PCL), and poly(trimethylene carbonate) (PTMC) at Li metal supported on Cu surfaces (Li/Cu) using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. In particular, the effect of copper (Cu) CCs on polymer stability, electronic structure, and their reduction reactions is investigated and compared to that of pure Li (100) surface. Through time-dependent Bader charge transfer analysis, electron transfer is identified as the triggering factor for polymer reduction. Based on the simulations, we find that the Cu CCs have a significant influence on the charge distribution of the Li metals, which increases electron transfer to the polymers and thereby accelerates polymers reduction. This thereby leads to different reaction mechanisms as compared to on Li-metal. The findings suggest that utilization of Cu CCs avoids the production of CO molecules and improves the quality of the formed SEI layer.
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