fixací

Fixací is a Czech term that refers to the act of fixing, stabilizing, or immobilizing something in various technical and scientific contexts. The word derives from fixace (fixation) and is used across disciplines to denote a process that preserves structure, integrity, or position by chemical, physical, or mechanical means.

In biology and medicine, fixation describes preserving biological specimens so their morphology remains recognizable for analysis. In microscopy, fixation immobilizes cells and tissues and often involves cross-linking proteins with agents such as formaldehyde or glutaraldehyde. Fixation aims to halt enzymatic activity and degradation, though different fixatives can influence antigenicity and ultrastructure. After fixation, samples may be embedded, sectioned, and stained for imaging. The choice of fixative, concentration, and duration depends on the desired preservation and downstream techniques.

In orthopedics and dentistry, fixation refers to immobilizing bones or teeth to promote healing or to secure prosthetic devices. Fracture fixation uses hardware such as pins, screws, plates, or external frames, with internal (osteosynthesis) or external fixation methods. The goal is to stabilize the injury to allow natural repair while maintaining alignment and function.

In photography and imaging, fixation describes the chemical process that renders a developed image permanent. A fixer, typically sodium thiosulfate or ammonium thiosulfate, dissolves undeveloped or unexposed silver halide crystals, preventing further light sensitivity and preventing image fading.

In biogeochemistry, nitrogen fixation denotes processes that convert atmospheric nitrogen (N2) into ammonia or related compounds usable by living organisms. This occurs biologically (in certain bacteria and cyanobacteria) and industrially (Haber-Bosch process).

See also fixative and fixation.