What is "absorption"

Absorption \Ab*sorp"tion\, n. [L. absorptio, fr. absorbere. See Absorb.]

1. The act or process of absorbing or sucking in anything, or of being absorbed and made to disappear; as, the absorption of bodies in a whirlpool, the absorption of a smaller tribe into a larger.

2. (Chem. & Physics) An imbibing or reception by molecular or chemical action; as, the absorption of light, heat, electricity, etc.

3. (Physiol.) In living organisms, the process by which the materials of growth and nutrition are absorbed and conveyed to the tissues and organs.

4. Entire engrossment or occupation of the mind; as, absorption in some employment.

1590s, from Latin absorptionem (nominative absorptio), noun of action from past participle stem of absorbere "swallow up" (see absorb).

n. 1 The act or process of absorbing or of being absorbed as, 2 # (context obsolete English) engulfing; swallowing up, as of bodies or land. (Attested from the late 16^th century until the mid 18^th century.)(R:SOED5: page=9) 3 # assimilate; incorporation. (First attested in the mid 18^th century.) 4 # (context chemistry physics English) the imbibing or reception by molecular or chemical action, of radiant energy; the process of being neutrons being absorbed by the nucleus; interception. (First attested in the mid 18^th century.) 5 # (context physiology English) in living organisms, the process by which the materials of growth and nutrition are absorbed and conveyed to the tissues and organs; taking in by various means, such as by osmosis. (First attested in the mid 18^th century.) 6 Entire engrossment or occupation of the mind. (First attested in the mid 19^th century.) 7 Mental assimilation. (First attested in the mid 20^th century.) 8 (context electrical engineering English) The retaining of electrical energy for a short time after it has been introduced to the dielectric. 9 The taking on of by a shipping company of special charges by another without price increase. 10 The natural lessening of radio waves due to atmospheric interference.

1. n. (chemistry) a process in which one substance permeates another; a fluid permeates or is dissolved by a liquid or solid [syn: soaking up]

2. (physics) the process in which incident radiated energy is retained without reflection or transmission on passing through a medium; "the absorption of photons by atoms or molecules"

3. the social process of absorbing one cultural group into harmony with another [syn: assimilation]

4. the process of absorbing nutrients into the body after digestion [syn: assimilation]

5. complete attention; intense mental effort [syn: concentration, engrossment, immersion]

6. the mental state of being preoccupied by something [syn: preoccupation, preoccupancy, engrossment]

Absorption may refer to:

In chemistry, absorption is a physical or chemical phenomenon or a process in which atoms, molecules or ions enter some bulk phase – gas, liquid or solid material. This is a different process from adsorption, since molecules undergoing absorption are taken up by the volume, not by the surface (as in the case for adsorption). A more general term is sorption, which covers absorption, adsorption, and ion exchange. Absorption is a condition in which something takes in another substance.

In many processes important in technology, the chemical absorption is used in place of the physical process, e.g., absorption of carbon dioxide by sodium hydroxide – such acid-base processes do not follow the Nernst partition law.

For some examples of this effect, see liquid-liquid extraction. It is possible to extract from one liquid phase to another a solute without a chemical reaction. Examples of such solutes are noble gases and osmium tetroxide.

The process of absorption means that a substance captures and transforms energy. The absorbent distributes the material it captures throughout whole and adsorbent only distributes it through the surface.

thumb|upright=2|right|An overview of electromagnetic radiation absorption. This example discusses the general principle using visible light as specific example. A white light source — emitting light of multiple wavelengths — is focused on a sample (the pairs of complementary colors are indicated by the yellow dotted lines). Upon striking the sample, photons that match the energy gap of the molecules present (green light in this example) are absorbed, exciting the molecules. Other photons are transmitted unaffected and, if the radiation is in the visible region (400–700 nm), the transmitted light appears as the complementary color (here red). By recording the attenuation of light for various wavelengths, an absorption spectrum can be obtained.

In physics, absorption of electromagnetic radiation is the way in which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the electromagnetic energy is transformed into internal energy of the absorber, for example thermal energy. The reduction in intensity of a light wave propagating through a medium by absorption of a part of its photons is often called attenuation. Usually, the absorption of waves does not depend on their intensity (linear absorption), although in certain conditions (usually, in optics), the medium changes its transparency dependently on the intensity of waves going through, and saturable absorption (or nonlinear absorption) occurs.

In economics, absorption is the total demand for all final marketed goods and services by all economic agents resident in an economy, regardless of the origin of the goods and services themselves. As the absorption is equal to the sum of all domestically-produced goods consumed locally and all imports, it is equal to national income [Y = C + I + G + (X - M)] minus the balance of trade [X - M].

The term was coined, and its relation to the balance of trade identified, by Sidney Alexander in 1952.

The term "absorption" is often used in real estate to assess demand for leasing space.

Acoustic absorption refers to the process by which a material, structure, or object takes in sound energy when sound waves are encountered, as opposed to reflecting the energy. Part of the absorbed energy is transformed into heat and part is transmitted through the absorbing body. The energy transformed into heat is said to have been 'lost'.
When sound from a loudspeaker collides with the walls of a room part of the sound's energy is reflected, part is transmitted, and part is absorbed into the walls. As the waves travel through the wall they deform the material thereof (just like they deformed the air before). This deformation causes mechanical losses via conversion of part of the sound energy into heat, resulting in acoustic attenuation, mostly due to the wall's viscosity. Similar attenuation mechanisms apply for the air and any other medium through which sound travels.
The fraction of sound absorbed is governed by the acoustic impedances of both media and is a function of frequency and the incident angle. Size and shape can influence the sound wave's behavior if they interact with its wavelength, giving rise to wave phenomena such as standing waves and diffraction.

Acoustic absorption is of particular interest in soundproofing. Soundproofing aims to absorb as much sound energy (often in particular frequencies) as possible converting it into heat or transmitting it away from a certain location.

In general, soft, pliable, or porous materials (like cloths) serve as good acoustic insulators - absorbing most sound, whereas dense, hard, impenetrable materials (such as metals) reflect most.

How well a room absorbs sound is quantified by the effective absorption area of the walls, also named total absorption area. This is calculated using its dimensions and the absorption coefficients of the walls. The total absorption is expressed in Sabins and is useful in, for instance, determining the reverberation time of auditoria. Absorption coefficients can be measured using a reverberation room, which is the opposite of an anechoic chamber (see below).

In pharmacology (and more specifically pharmacokinetics), absorption is the movement of a drug into the bloodstream.

Absorption involves several phases. First, the drug needs to be introduced via some route of administration ( oral, topical-dermal, etc.) and in a specific dosage form such as a tablet, capsule, solution and so on.

In other situations, such as intravenous therapy, intramuscular injection, enteral nutrition and others, absorption is even more straightforward and there is less variability in absorption and bioavailability is often near 100%. It is considered that intravascular administration (e.g. IV) does not involve absorption, and there is no loss of drug. The fastest route of absorption is inhalation, and not as mistakenly considered the intravenous administration.

Absorption is a primary focus in drug development and medicinal chemistry, since the drug must be absorbed before any medicinal effects can take place. Moreover, the drug's pharmacokinetic profile can be easily and significantly changed by adjusting factors that affect absorption.

Skin absorption is a route by which substances can enter the body through the skin. Along with inhalation, ingestion and injection, dermal absorption is a route of exposure for toxic substances and route of administration for medication. Absorption of substances through the skin depends on a number of factors, the most important of which are concentration, duration of contact, solubility of medication, and physical condition of the skin and part of the body exposed.

Skin (percutaneous, dermal) absorption is a term that describes the transport of chemicals from the outer surface of the skin both into the skin and into circulation. Skin absorption relates to the degree of exposure to and possible effect of a substance which may enter the body through the skin. Human skin comes into contact with many agents intentionally and unintentionally. Skin absorption can occur from occupational, environmental, or consumer skin exposure to chemicals, cosmetics, or pharmaceutical products. Some chemicals can be absorbed in enough quantity to cause detrimental systemic effects. Skin disease ( dermatitis) is considered one of the most common occupational diseases. In order to assess if a chemical can be a risk of either causing dermatitis or other more systemic effects and how that risk may be reduced one must know the extent to which it is absorbed, thus dermal exposure is a key aspect of human health risk assessment.

Absorption is a valid argument form and rule of inference of propositional logic. The rule states that if P implies Q, then P implies P and Q. The rule makes it possible to introduce conjunctions to proofs. It is called the law of absorption because the term Q is "absorbed" by the term P in the consequent. The rule can be stated:

$$\frac{P \to Q}{\therefore P \to (P \and Q)}$$

where the rule is that wherever an instance of "P → Q" appears on a line of a proof, "$P \to (P \and Q)$" can be placed on a subsequent line.

Absorption is a disposition or personality trait in which a person becomes absorbed in his or her mental imagery, particularly fantasy. This trait thus correlates highly with a fantasy-prone personality. The original research on absorption was by American psychologist Auke Tellegen. The construct of absorption was developed in order to relate individual differences in hypnotisability to broader aspects of personality. Absorption has a variable correlation with hypnotisability (r =.13-89) perhaps because in addition to broad personality dispositions, situational factors play an important role in performance on tests of hypnotic susceptibility. Absorption is one of the traits assessed in the Multidimensional Personality Questionnaire.