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

The street hawker

It’s 1985 Singapore, Kway Teow Ong runs a street hawker stall at a bustling back alley. One night, an unexpected encounter leads to him meeting the Pink Lady who resembles his wife who has passed away. Amidst reminiscing about the past with his fellow hawker friend, Fishball Lim, they are being ambushed by the inspectors in which they narrowly escaped. Back home, Ong is further nagged by his daughter, Xing, to quit. In the midst of these setbacks, he finds solace chatting with the Pink Lady, and even sharing his Char Kway Teow recipe with her. Reality finally sinks in when Lim reveals his intention to retire from street hawking and Ong is further disheartened by the drop in customers since the raid. As Ong and Xing are about to wrap up for the night, Pink Lady approaches Ong to request for one more plate of Char Kway Teow on her last day in Singapore. Ong gladly agrees. Whilst preparing, they are halted by the authorities. Agitated, Xing stands up for her father and confronts the inspectors. The inspectors eventually decide to let Ong off to enjoy one last meal together with his daughter and Pink Lady.Bachelor of Fine Art

Equilibria, kinetics and mechanism for the degradation of the cytotoxic compound L-N^G-nitroarginine

10.1080/03639045.2017.1405974Drug Development and Industrial Pharmacy444624-63