Where does liquefaction collide?

In physical chemistry, liquefaction is the conversion of a gas into a liquid by cooling it and compressing it below its critical temperature and pressure, so the molecules draw close enough to condense. Faraday's 1823 On fluid chlorine reported liquefying chlorine gas by generating it under pressure in a sealed tube, one of the first demonstrations that ordinary gases could be forced into the liquid state. The referent is a controlled phase change of a substance in the laboratory or an industrial plant, defined by its critical point, and it has nothing to do with soil failing in an earthquake or dead tissue turning to liquid, beyond the shared word for becoming liquid.[1]

Unit

The temperature and pressure at which a gas condenses to liquid, relative to its critical point

Recovery means

The liquid returns to gas on warming above its boiling point; the change is reversible with temperature and pressure

Measured by

Determined from phase diagrams, critical constants, and the pressures and temperatures needed to condense a given gas

In geotechnical engineering, liquefaction is the sudden loss of strength and stiffness in saturated, loose, sandy soil when earthquake shaking drives up the water pressure between grains until the soil can no longer carry load and briefly behaves like a heavy liquid, so buildings tilt and the ground fails. Seed and Idriss's 1971 Simplified procedure for evaluating soil liquefaction potential gave the standard method for judging whether a site will liquefy under a design earthquake. The referent is a transient mechanical failure of the ground under cyclic loading, assessed from soil tests and shaking intensity, and it is a wholly different thing from condensing a gas or the digestion of dead tissue.[2]

Unit

The pore-water pressure and cyclic stress at which soil loses shear strength

Recovery means

Strength returns as excess pore pressure dissipates and the soil reconsolidates after shaking stops

Measured by

Evaluated by cyclic stress ratio against soil resistance from penetration tests, and observed as sand boils and ground failure

In pathology, liquefaction (liquefactive necrosis) is a pattern of cell death in which enzymes digest the dead tissue into a soft, viscous, often pus-filled liquid mass, the pattern typical of brain infarcts and of abscesses caused by bacteria and fungi. Kumar, Abbas, and Aster's Robbins and Cotran Pathologic Basis of Disease sets out liquefactive necrosis alongside the other patterns of tissue death and the enzymatic mechanism that dissolves the tissue. The referent is a mode of tissue breakdown in a patient, identified by its appearance under the microscope and on imaging, and it is unrelated to condensing a gas or the seismic failure of soil, joined only by the meaning of turning to liquid.[3]

Unit

The transformation of dead tissue into a liquid, viscous mass

Recovery means

Not applicable

Measured by

Identified by histology and by the softened, fluid appearance of the affected tissue on imaging