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In chemistry, a steady state is a situation in which all state variables are constant in spite of ongoing processes that strive to change them. For an entire system to be at steady state, i.e. for all state variables of a system to be constant, there must be a flow through the system (compare mass balance). A simple example of such a system is ...
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
Plateau principle. The plateau principle is a mathematical model or scientific law originally developed to explain the time course of drug action (pharmacokinetics). [1] The principle has wide applicability in pharmacology, physiology, nutrition, biochemistry, and system dynamics. It applies whenever a drug or nutrient is infused or ingested at ...
Pharmacokinetics. A graph depicting a typical time course of drug plasma concentration over 96 hours, with oral administrations every 24 hours. The main pharmacokinetic metrics are annotated. Steady state is reached after about 5 × 12 = 60 hours. Pharmacokinetics (from Ancient Greek pharmakon "drug" and kinetikos "moving, putting in motion ...
The convection–diffusion equation can be derived in a straightforward way [4] from the continuity equation, which states that the rate of change for a scalar quantity in a differential control volume is given by flow and diffusion into and out of that part of the system along with any generation or consumption inside the control volume: + =, where j is the total flux and R is a net ...
The rate equation for the rate of formation of product P may be obtained by using the steady-state approximation, in which the concentration of intermediate A* is assumed constant because its rates of production and consumption are (almost) equal. [8] This assumption simplifies the calculation of the rate equation.
In this example, there are two substances: solids and water. The water overflow outlet carries an increased concentration of water relative to solids, as compared to the slurry inlet, and the exit of the conveyor belt carries an increased concentration of solids relative to water. Assumptions. Steady state; Non-reactive system; Analysis
Clearance (pharmacology) In pharmacology, clearance ( ) is a pharmacokinetic parameter representing the efficiency of drug elimination. This is the rate of elimination of a substance divided by its concentration. [1] The parameter also indicates the theoretical volume of plasma from which a substance would be completely removed per unit time.