Biological organs, fluids

Biological fouling biological organisms attach to heat transfer surface and build a surface to prevent good fluid contact with the tube surface. 

Liquid crystal sounds like a contradiction. Liquids are fluid, their molecules continually changing places in a manner that is not particularly well organized. Crystals are immobile, their molecules locked into fixed positions that form regular patterns. Yet, not only does this unusual combination of fluidity and regular patterns exist, it plays important roles in biological organisms. 

Fluids are important to biological organisms because they fill interior spaces and completely surround every organism. Water and air are the two most important fluids for biological systems air because it supplies oxygen, acts as a sink for excess carbon dioxide, and can dry the organism and water because it acts as a solvent, attaches to dissolved molecules (see Section 3.2), and is relatively thick. 

Hyaluronic acid is a viscoelastic fluid filled in the space between cells and collagenous fibers and coated on some epidermal tissues. Hyaluronic acid plays an important role in the biological organism as a mechanical support of the cells of many tissues, such as the skin, the tendons, the muscles and cartilage. Hyaluronic acid also performs other functions in biological processes, such as moistening of tissues, lubrication, and cellular migration (28). 

Supercritical fluid extraction (SFE) and Solid Phase Extraction (SPE) are excellent alternatives to traditional extraction methods, with both being used independently for clean-up and/or analyte concentration prior to chromatographic analysis. While SFE has been demonstrated to be an excellent method for extracting organic compounds from solid matrices such as soil and food (36, 37), SPE has been mainly used for diluted liquid samples such as water, biological fluids and samples obtained after-liquid-liquid extraction on solid matrices (38, 39). The coupling of these two techniques (SPE-SFE) turns out to be an interesting method for the quantitative transfer... 

Gases, fluids, crystals, and lasers are all examples of complex systems that are familiar to ns from physics. Chemical reactions, in which a large number of molecules conspire to produce new molecules, are also good examples. From biology, we have DNA molecules built up from amino acids, cells built from molecules, and organisms built from colls. 

The dense fluid that exists above the critical temperature and pressure of a substance is called a supercritical fluid. It may be so dense that, although it is formally a gas, it is as dense as a liquid phase and can act as a solvent for liquids and solids. Supercritical carbon dioxide, for instance, can dissolve organic compounds. It is used to remove caffeine from coffee beans, to separate drugs from biological fluids for later analysis, and to extract perfumes from flowers and phytochemicals from herbs. The use of supercritical carbon dioxide avoids contamination with potentially harmful solvents and allows rapid extraction on account of the high mobility of the molecules through the fluid. Supercritical hydrocarbons are used to dissolve coal and separate it from ash, and they have been proposed for extracting oil from oil-rich tar sands. 

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