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  2. Countercurrent exchange - Wikipedia

    en.wikipedia.org/wiki/Countercurrent_exchange

    The theory was acknowledged a year later after a meticulous study showed that there is almost no osmotic difference between liquids on both sides of nephrons. [16] Homer Smith , a considerable contemporary authority on renal physiology, opposed the model countercurrent concentration for 8 years, until conceding ground in 1959. [ 17 ]

  3. Chart of accounts - Wikipedia

    en.wikipedia.org/wiki/Chart_of_accounts

    A chart of accounts (COA) is a list of financial accounts and reference numbers, grouped into categories, such as assets, liabilities, equity, revenue and expenses, and used for recording transactions in the organization's general ledger. Accounts may be associated with an identifier (account number) and a caption or header and are coded by ...

  4. Gibbs–Donnan effect - Wikipedia

    en.wikipedia.org/wiki/Gibbs–Donnan_effect

    Donnan equilibrium across a cell membrane (schematic). The Gibbs–Donnan effect (also known as the Donnan's effect, Donnan law, Donnan equilibrium, or Gibbs–Donnan equilibrium) is a name for the behaviour of charged particles near a semi-permeable membrane that sometimes fail to distribute evenly across the two sides of the membrane. [1]

  5. Mass transfer coefficient - Wikipedia

    en.wikipedia.org/wiki/Mass_transfer_coefficient

    The driving force shown here as ' ' is expressed in units of moles per unit of volume, but in some cases the driving force is represented by other measures of concentration with different units. For example, the driving force may be partial pressures when dealing with mass transfer in a gas phase and thus use units of pressure.

  6. Optimality model - Wikipedia

    en.wikipedia.org/wiki/Optimality_model

    Optimality modeling is the modeling aspect of optimization theory. It allows for the calculation and visualization of the costs and benefits that influence the outcome of a decision, and contributes to an understanding of adaptations. The approach based on optimality models in biology is sometimes called optimality theory. [1]

  7. Pressure flow hypothesis - Wikipedia

    en.wikipedia.org/wiki/Pressure_Flow_Hypothesis

    According to the hypothesis, the high concentration of organic substances, particularly sugar, inside the phloem at a source such as a leaf creates a diffusion gradient (osmotic gradient) that draws water into the cells from the adjacent xylem. This creates turgor pressure, also called hydrostatic pressure, in the phloem. The hypothesis states ...

  8. Molecular diffusion - Wikipedia

    en.wikipedia.org/wiki/Molecular_diffusion

    Before this point in time, a gradual variation in the concentration of A occurs along an axis, designated x, which joins the original compartments. This variation, expressed mathematically as -dC A /dx, where C A is the concentration of A. The negative sign arises because the concentration of A decreases as the distance x increases.

  9. Electrochemical gradient - Wikipedia

    en.wikipedia.org/wiki/Electrochemical_gradient

    The chemical gradient, or difference in solute concentration across a membrane. The electrical gradient, or difference in charge across a membrane. If there are unequal concentrations of an ion across a permeable membrane, the ion will move across the membrane from the area of higher concentration to the area of lower concentration through ...