Robust estimation of bacterial cell count from optical density

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

Synthesis, mesomorphism, and luminescent properties of Calamitic 2-Phenylpyridines and their complexes with Platinum(II)

The liquid crystal and luminescent properties of two related series of rod-like, ortho-platinated complexes bearing a β-diketonate co-ligand are reported. The parent ligands exhibit a rich, smectic polymorphism, but when modified with a fused cyclopentene ring, nematic phases dominate. Reaction of the ligands with tetrachloroplatinate(II) leads to poorly soluble, dimeric complexes that can be cleaved using dimethylsulfoxide; the resulting monomeric complexes are then readily converted to the β-diketonate complexes. All of the complexes are mesomorphic, and the β-diketonate complexes have excited state lifetimes of 27 μs with emission quantum efficiencies exceeding 0.5, the highest yet reported for materials of this type

Polarizing Fe-Co-Fe Planar Waveguides for the Production of Neutron Microbeams

AbstractPlanar waveguides can transform a conventional neutron beam into a very narrow but slightly divergent microbeam. Such microbeams could be used for the investigation of nanostructures with a high spatial resolution. We have investigated the tri-layer magnetic structure Fe/Co/Fe which transforms an unpolarized incident beam into a polarized microbeam. The polarized neutron reflectometer NREX with a horizontal sample plane was used for the waveguide characterization. Some practical aspects of microbeam extraction and polarization are discussed

Synthesis, Mesomorphism, and Luminescent Properties of Calamitic 2-Phenylpyridines and Their Complexes with Platinum(II)

The liquid crystal and luminescent properties of two related series of rod-like, ortho-platinated complexes bearing a β-diketonate co-ligand are reported. The parent ligands exhibit a rich, smectic polymorphism, but when modified with a fused cyclopentene ring, nematic phases dominate. Reaction of the ligands with tetrachloroplatinate(II) leads to poorly soluble, dimeric complexes that can be cleaved using dimethylsulfoxide; the resulting monomeric complexes are then readily converted to the β-diketonate complexes. All of the complexes are mesomorphic, and the β-diketonate complexes have excited state lifetimes of 27 μs with emission quantum efficiencies exceeding 0.5, the highest yet reported for materials of this type

Synthesis, Mesomorphism, and Luminescent Properties of Calamitic 2-Phenylpyridines and Their Complexes with Platinum(II)

The liquid crystal and luminescent properties of two related series of rod-like, ortho-platinated complexes bearing a β-diketonate co-ligand are reported. The parent ligands exhibit a rich, smectic polymorphism, but when modified with a fused cyclopentene ring, nematic phases dominate. Reaction of the ligands with tetrachloroplatinate(II) leads to poorly soluble, dimeric complexes that can be cleaved using dimethylsulfoxide; the resulting monomeric complexes are then readily converted to the β-diketonate complexes. All of the complexes are mesomorphic, and the β-diketonate complexes have excited state lifetimes of 27 μs with emission quantum efficiencies exceeding 0.5, the highest yet reported for materials of this type

Frequency and Time Domain Analysis of sRNA-based Treatment for Inflammatory Bowel Disease

The validity of a complex reaction pathway pro- posed to treat Inflammatory Bowel Disease (IBD) was verified by a comprehensive time and frequency domain analysis. The model was taken to the frequency domain to study the effect and the significance of the negative feedback loop introduced by the reaction pathways. It could be shown that such proposed probiotics have very interesting potentials that could be used extensively in near future