| 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. |
- Wu, Jian, et al.
(author)
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Effects of carbon dioxide addition to fuel on soot evolution in ethylene and propane diffusion flames
- 2019
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In: Combustion and Flame. - : Elsevier BV. - 0010-2180. ; 199, s. 85-95
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Journal article (peer-reviewed)abstract
- The influence of carbon dioxide addition to the fuel on soot evolution in ethylene and propane diffusion flames was studied by optical diagnostics. The mole fraction of CO2 addition ranged from 0 to 0.5, while the flow rate of the fuel gas was kept constant for these two sets of flames. Spatial distributions of polycyclic aromatic hydrocarbons (PAHs), temperature, as well as volume fraction, primary particle size and number density of soot were observed by the methods of laser-induced fluorescence (LIF), ratio pyrometry and laser-induced incandescence (LII), respectively. It was found that the flame height decreased for ethylene flames while it was nearly constant for propane flames with increasing addition of CO2. The measurements showed a temperature reduction in the lower part but an increase in the upper part in the ethylene-based flames. By contrast, a slight temperature decrease was observed in overall propane-based flames with the addition of CO2. Similar suppression effects were observed in the total soot/PAHs loading, percentage of carbon conversion to soot, and the total number of primary soot particles regardless of the fuel type. Comparison between the total loading of soot and PAHs indicated that addition of CO2 inhibited the conversion of PAHs to soot. The results also showed that the addition of CO2 in the fuel had a small effect on the specific growth rate of soot regardless of the fuel type. Relative changes of particle surface area could reasonably well explain the shift in the peak volume fraction from the wings to the centerline with the addition of CO2 to the ethylene flames.
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| 3. |
- Wu, Jian, et al.
(author)
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Optical investigations on particles evolution and flame properties during pulverized coal combustion in O 2 /N 2 and O 2 /CO 2 conditions
- 2019
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In: Fuel. - : Elsevier BV. - 0016-2361. ; 251, s. 394-403
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Journal article (peer-reviewed)abstract
- The evolution of soot and coal/char as well as the flame properties, during pulverized coal combustion in O 2 /N 2 and O 2 /CO 2 conditions, were experimentally studied using optical diagnostics. The jet flames of pulverized coal particles were produced by using an entrained-flow reactor with optical access, and the oxygen concentrations of the gas carrying pulverized coal particles were varied between 0 and 100%. A combination of laser-induced incandescence (LII), laser-induced fluorescence (LIF), elastic laser scattering (ELS), and radiative emission detection methods was employed to characterize the spatial distributions of soot, polycyclic aromatic hydrocarbons (PAHs), coal/char, and the flame temperature. The measured results revealed that ELS signal intensity declined accompanied with the appearance of LIF and LII signals. An evolution pattern of PAHs and soot was investigated to be similar to those found in gaseous hydrocarbon diffusion flames. An abrupt expansion of the pulverized coal particle jet was observed from ELS measurement at the position where coal particle jet was ignited, which was likely attributed to the more intensive dispersion of small particles caused by a rapid elevation of the flame temperature. As the oxygen concentration increased, the ignition distance of pulverized coal particle jet became shorter and the flame temperature increased. The PAHs and soot-loaded regions were shrunk and the sooting region shifted to upstream position of the flame. Nonetheless, replacing N 2 with CO 2 tended to increase the ignition distance but lower the flame temperature. The peak LII signal, corresponding to the maximum soot volume fraction, increased to a maximum and then decreased with oxygen concentration and the intensity for the O 2 /N 2 case was far larger than for the O 2 /CO 2 case. However, the LIF signal intensities exhibited an apparent decrease with increasing oxygen concentration, and they were nearly consistent when N 2 was replaced with CO 2 , which may imply that the effect of suppressing radical formation on PAHs evolution in CO 2 atmosphere was negligible.
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| 4. |
- Wang, Zhihang, 1989, et al.
(author)
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Chip-scale solar thermal electrical power generation
- 2022
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In: Cell Reports Physical Science. - : Elsevier BV. - 2666-3864. ; 3:3
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Journal article (peer-reviewed)abstract
- There is an urgent need for alternative compact technologies that can derive and store energy from the sun, especially the large amount of solar heat that is not effectively used for power generation. Here, we report a combination of solution- and neat-film-based molecular solar thermal (MOST) systems, where solar energy can be stored as chemical energy and released as heat, with microfabricated thermoelectric generators to produce electricity when solar radiation is not available. The photophysical properties of two MOST couples are characterized both in liquid with a catalytical cycling setup and in a phase-interconvertible neat film. Their suitable photophysical properties let us combine them individually with a microelectromechanical ultrathin thermoelectric chip to use the stored solar energy for electrical power generation. The generator can produce, as a proof of concept, a power output of up to 0.1 nW (power output per unit volume up to 1.3 W m−3). Our results demonstrate that such a molecular thermal power generation system has a high potential to store and transfer solar power into electricity and is thus potentially independent of geographical restrictions.
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