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- 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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- Hu, Kaibo, et al.
(författare)
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Highly selective recovery of rare earth elements from mine wastewater by modifying kaolin with phosphoric acid
- 2023
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Ingår i: Separation and Purification Technology. - : Elsevier. - 1383-5866 .- 1873-3794. ; 309
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Tidskriftsartikel (refereegranskat)abstract
- Recovery of rare earth elements (REEs) from mine wastewater is essential for maintaining rare earth reserves and sustainable application of REEs. In the present study, we prepared a phosphoric acid modified kaolin (P-K) adsorbent by a simple mechanochemical process for the selective recovery of REEs from rare earth wastewater. The impacts of phosphoric acid dosage, milling duration, initial pH, temperature, initial ion concentration, and adsorbent dosage on the selective adsorption of REEs were investigated. The findings demonstrate that the adsorption of REEs by P-K follows pseudo-second-order kinetic model and the Langmuir isotherm model, and is dominated by chemical adsorption, with a maximum adsorption capacity of 19.82Â mg/g at 50 â. Additionally, in an original mine wastewater, the recovery rate of REEs can reach more than 90%, whereas the adsorption rates of calcium, magnesium and, ammonia nitrogen (whose concentration is 18 times that of REEs) are nearly zero, indicating that P-K has extremely high selectivity for REEs. Furthermore, the feedstock solution containing 40Â mg/L of REEs may be concentrated to 3510Â mg/L following enrichment treatment, and 99.9% of the REEs are eluted using a low concentration of hydrochloric acid. The findings illustrate that P-K has a wide range of potential applications in the treatment of rare earth industrial effluents.
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