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Nerve agents, sometimes also called nerve gases, are a class of organic chemicals that disrupt the mechanisms by which nerves transfer messages to organs. The disruption is caused by the blocking of acetylcholinesterase (AChE), an enzyme that catalyzes the breakdown of acetylcholine , a neurotransmitter .
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical reaction occurs. [1] A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage of an overall chemical reaction. The detailed steps of a reaction are not observable in most cases.
In chemistry, a reagent (/ r i ˈ eɪ dʒ ən t / ree-AY-jənt) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. [1] The terms reactant and reagent are often used interchangeably, but reactant specifies a substance consumed in the course of a chemical reaction. [ 1 ]
The compound providing the acyl group is called the acylating agent. The substrate to be acylated and the product include the following: alcohols, esters; amines, amides; arenes or alkenes, [1] ketones; A particularly common type of acylation is acetylation, the addition of the acetyl group.
In the fields of histology, pathology, and cell biology, fixation is the preservation of biological tissues from decay due to autolysis or putrefaction.It terminates any ongoing biochemical reactions and may also increase the treated tissues' mechanical strength or stability.
Iodinated contrast contains iodine.It is the main type of radiocontrast used for intravenous administration.Iodine has a particular advantage as a contrast agent for radiography because its innermost electron ("k-shell") binding energy is 33.2 keV, similar to the average energy of x-rays used in diagnostic radiography.
A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. [1] Contrast agents absorb or alter external electromagnetism or ultrasound , which is different from radiopharmaceuticals , which emit radiation themselves.
Monomer to RAFT reagent: gives the expected degree of polymerization (that is, the number of monomer units in each polymer chain) and can be used to estimate the molecular weight of the polymer by Equation (1) (see below). [12] [14] RAFT reagent to initiator: determines the end groups on the polymer chains.