| 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. |
- Chen, Shao, et al.
(author)
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Regioselective Acylation of 2 '- or 3 '-Hydroxyl Group in Salicin : Hemisynthesis of Acylated Salicins
- 2014
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In: Chemical Research in Chinese Universities. - : Springer Science and Business Media LLC. - 1005-9040 .- 2210-3171. ; 30:5, s. 774-777
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Journal article (peer-reviewed)abstract
- Salicin-based phenolic glycosides(PGs) are important defensive substances against herbivore feeding and have good bioactivities. In this work, a novel approach for the synthesis of salicin-based PGs has been developed, by which PGs of 2'-O-acetylsalicin(5a), 3'-O-acetylsalicin(5b) and 3'-O-benzoylsalicin(5d) were hemisynthesized. The effects of acylation reagent, solvent and temperature on the regioselective acylation of 2'- or 3'-hydroxyl groups of salicin mediated by dibutyltin oxide were investigated. The optimal conditions under which the best regioselectivity reached for 5a-5d were discovered, respectively. Moreover, a tentative tin-oxygen coordination mechanism was put forward to explain the different regioselectivities shown under different conditions.
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| 3. |
- Pei, Yuxin, et al.
(author)
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Photoderivatized polymer thin films at quartz crystal microbalance surfaces : Sensors for carbohydrate-protein interactions
- 2007
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 79:18, s. 6897-6902
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Journal article (peer-reviewed)abstract
- Photoderivatized polymer-coated gold surfaces have been developed following a perfluorophenylazide-based double ligation strategy. Gold-plated quartz crystal microbalance (QCM) crystals were initially covalently functionalized with a monolayer of poly(ethylene glycol) (PEG), using photo-or thermolytic nitrene formation and insertion. The polymer surfaces were subsequently used as substrates for photoinsertion of carbohydrate-derivatized photoprobes, yielding different recognition motifs for selective protein binding. The resulting robust and biocompatible sensor surfaces were applied to a flow-through QCM instrument for monitoring lectin-carbohydrate interactions in real time. The results clearly show the predicted lectin selectivity, demonstrating the applicability of the approach.
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| 4. |
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| 5. |
- Brule, Emile, et al.
(author)
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Chelating phosphines with C-2 and C-3 symmetry
- 2004
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In: Mendeleev communications (Print). - 0959-9436 .- 1364-551X. ; :6, s. 276-277
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Journal article (peer-reviewed)abstract
- Antide formation between ring opened aziridines and 2-(diphenylphosphino)benzoic acid provides an easy access to chelating di- and triphosphines with C-2 and C-3 symmetry.
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| 6. |
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| 7. |
- Gonzalez, Nelida J. D., et al.
(author)
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New method for resolving the enantiomeric composition of 2-methyltetrols in atmospheric organic aerosols
- 2011
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In: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1218:51, s. 9288-9294
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Journal article (peer-reviewed)abstract
- In order to facilitate the determination of the primary and secondary origin of atmospheric organic aerosols, a novel method involving chiral capillary gas chromatography coupled with mass spectrometry has been developed and validated. The method was focused on the analysis of 2-methylerythritol and 2-methylthreitol, considered to be tracers of secondary organic aerosols from the oxidation of atmospheric isoprene. The method was validated by performing various tests using authentic standards, including pure enantiomeric standards. The result showed that the analytical method itself does not affect the enantiomeric composition of the samples analyzed. The method was applied on atmospheric aerosols from a boreal forest collected in Aspvreten, Sweden and on laboratory samples obtained from liquid phase oxidation of isoprene and smog chamber experiments. Aerosol samples contained one enantiomer of 2-methylerythritol in significantly larger quantities than the others. In contrast, the liquid-phase oxidation of isoprene and its gas-phase oxidation in the smog chamber produced all enantiomers in equal quantities. The results obtained where the enantiomer fraction, EF, is larger than 0.50 suggest that 2-methyltetrols in atmospheric aerosols may also have biological origin. Information about the differences between enantiomer fractions obtained using this method brings new insights in the area of atmospheric aerosols.
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| 8. |
- Grutters, Michiel M. P., et al.
(author)
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Highly Selective Cobalt-Catalyzed Hydrovinylation of Styrene
- 2009
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In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 351:13, s. 2199-2208
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Journal article (peer-reviewed)abstract
- Phosphine complexes of cobalt halide salts activated by diethylaluminum chloride are shown to yield highly active catalysts in the hydrovinylation of styrene, with unprecedented high selectivity to the desired product 3-phenyl-1-butene (3P1B). Double-bond isomerization, a common problem in codimerization reactions, only occurs after full conversion with these catalyst systems, even at elevated temperature. The most active catalysts are based on cobalt halide species combined with either C-1- or C-2-bridged diphosphines, heterodonor P,N or P,O ligands, flexible bidentate phosphine ligands or monodentate phosphine ligands. Kinetic investigations show an order > 1 in catalyst, which indicates either the involvement of dinuclear species in the catalytic cycle or partial catalyst decomposition via a bimolecular pathway.
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