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In 1972, Tutte posed the 3‐Flow Conjecture: that all 4‐edge‐connected graphs have a nowhere‐zero 3‐flow. This was extended by Jaeger et al. to allow vertices to have a prescribed, possibly nonzero difference (modulo 3) between the inflow and outflow. They conjectured that all 5‐edge‐connected graphs with a prescription function have a nowhere‐zero 3‐flow meeting that prescription. Kochol showed that...
A `catcher' based on a revolving cylindrical collector is described. The simple and inexpensive device reduces free‐jet instabilities inherent to high‐viscosity extrusion injection, facilitating delivery of microcrystals for serial diffraction X‐ray crystallography.