#chemist

• From the beginning — A Latin phrase meaning 'from the beginning' or 'from first principles'. In biochemistry and computational pharmacology, it refers to calculations or simulations based strictly on the laws of quantum mechanics, without relying on preexisting empirical data (e.g., ab initio protein folding). In forensic medicine, it describes an act, toxic exposure, or pathological condition present from the very start.
• Abderhalden reaction — A medical eponym linked to the biochemist Emil Abderhalden, used to denote the immunological defense reaction (Abderhalden reaction) based on protective enzymes in the serum, previously used for the early diagnosis of pregnancy or certain oncological and psychiatric conditions (such as dementia praecox). The term also defines the Abderhalden-Kaufmann-Lignac syndrome, a rare congenital metabolic disorder characterized by cystinosis and renal dwarfism.
• Abi- (combining form) — A learned combining form used as a prefixoid (a variant of the prefix 'abio-') to denote the absence of life, the lack of living organisms, or organic processes taking place outside active biological structures. In biochemistry and clinical pharmacology, it forms technical terms describing sterile environments, artificial chemical syntheses of genetic compounds, or molecular reactions completely devoid of living cellular interaction.
• Abientin / Abietic compound — A technical specialty term designating an organic compound, an acid derivative, or a resinous substance extracted or isolated from the cellular structures of conifers, specifically from the genus Abies (fir). In pharmaceutical chemistry and pharmacognosy, abientin properties are analyzed due to their antiseptic, anti-inflammatory, and expectorant potential, with acids of this class serving as precursors in synthesizing dermatological ointments and pulmonary inhalation products.
• Abietin — A resinous substance of diterpenic nature, historically extracted from the resin of certain conifer species (especially from the genus Abies). In early pharmacognosy and 19th-century academic folk medicine, it was used as an active ingredient in formulating vulnerary ointments, anti-rheumatic plasters, or as a balsamic stimulant for the respiratory mucous membranes, due to its antiseptic and healing properties.
• Abrastol — The calcium salt of sulfo-beta-naphthol, used historically in the food and winemaking industries as an antiseptic, preservative, and stabilizing agent for fermented beverages; a chemical compound from the naphthol derivatives class later banned by modern sanitary laws due to its high toxic potential on the organism.
• Acaroid — Resembling a mite in shape or appearance; ovoid, compact, and lacking visible body segmentation. In botany and chemistry, the term designates 'acaroid resin' (or acaroid gum), a natural yellow or reddish resinous substance extracted from Australian plants of the genus Xanthorrhoea, traditionally used in industry for manufacturing varnishes, spirits, printing inks, and in pyrotechnics due to its excellent burning properties.
• Acrolein — A volatile, colorless or yellowish liquid with an extremely pungent, suffocating, and tear-inducing odor, with the chemical formula CH2=CH-CHO; propenal. It is a highly toxic unsaturated aldehyde formed by the dehydration of glycerol.
• Actinism — A rare historical or technical term used to describe the property or intensity of luminous radiation to produce chemical or structural changes in the materials it traverses or strikes. This phenomenon constitutes the historical basis of photochemical processes, being closely linked to actinism and the study of how solar or artificial light interacts directly with photographic emulsion or other substances sensitive to the ultraviolet spectrum.
• Actinic — Relating to radiation or luminous flux; capable of producing intense chemical (and photochemical) changes or reactions in the substances it strikes or traverses. Actinic properties are characteristic primarily of ultraviolet spectrum radiation and short-wave solar rays, being essential in the exposure process of conventional photographic emulsions or in triggering biological phenomena within living tissues.
• Actinide — A metallic and radioactive chemical element belonging to the actinide (or actinoid) series, a stabilized structural group of 15 heavy elements located in the periodic table from actinium (atomic number 89) to lawrencium (atomic number 103). All these elements belong to the 'f' block (5f series) of transition metals, characterized by high nuclear instability, high density, and electrochemical properties closely correlated with those of actinium.
• Actinides — Plural form for the neuter noun 'actinid'; a homogeneous structural group in the periodic table consisting of 15 metallic and radioactive chemical elements, with atomic numbers ranging from 89 (actinium) to 103 (lawrencium). Located in the 'f' block of transition elements in the 7th period, they exhibit similar chemical properties due to the progressive filling of the 5f electron subshell, being recognized for their high density, substantial nuclear instability, and capacity to undergo fission.
• Actinogenic — Producing, generating, or emitting rays or radiation, particularly within the luminous, ultraviolet, or x-ray spectrum. In applied physics and chemistry, the term describes substances, devices, or phenomena capable of acting as structural sources of radiant energy, possessing the property to trigger photochemical reactions or molecular transformations in the surrounding environment via the emitted flux.
• Actinism — A structural and physiological property of luminous radiation, particularly short-wavelength radiation within the ultraviolet spectrum, to induce chemical reactions or molecular modifications in directly exposed photosensitive substances. This phenomenon constitutes the historical foundation of analog photographic technologies, light-triggered chemical synthesis processes, and complex biological reactions within living tissues.
• Actinium — A radioactive, silvery-white metallic chemical element with atomic number 89 and symbol Ac, which initiates the actinide series in the periodic table. Discovered in 1899 by André-Louis Debierne, actinium is extremely rare in the Earth's crust, occurring in trace amounts within uranium ores. Structurally, it crystallizes in a face-centered cubic system, is highly reactive, and emits an intense bluish glow in the dark due to the ionization of the surrounding air.
• Actinium — The original neological form, Latin spelling, and official international English name for the chemical element 'actiniu' (symbol Ac, atomic number 89). This structural term defines the heavy radioactive metal in the 'f' block of the periodic table, used within global scientific literature and IUPAC standards to describe the properties of isotopes involved in nuclear fission processes or advanced oncological medical research.
• Actinogenic — Producing, generating, or emitting rays or radiation, particularly within the luminous, ultraviolet, or x-ray spectrum. In applied physics and chemistry, the term describes substances, devices, or phenomena capable of acting as structural sources of radiant energy, possessing the property to trigger photochemical reactions or molecular transformations in the surrounding environment via the emitted flux.
• Actinography — A historical medical and scientific term used in the past as a synonym for radiography or the technique of obtaining internal structural images of solid bodies using X-rays or other active radiant beams. In old applied physics, it also defined the general method of printing or recording onto a photosensitive film the chemical effects directly caused by exposure to an electromagnetic wave flux within the ultraviolet spectrum.
• Actinoid — The official systematic name recommended by IUPAC for any chemical element within the actinide series, encompassing the 15 metallic and radioactive elements with atomic numbers from 89 (actinium) to 103 (lawrencium). As an adjective, it describes a chemical behavior or atomic structure resembling that of actinium, characterized by the progressive filling of the 5f electron subshell, very high density, and electrochemical properties specific to heavy metals.
• Actinology — An interdisciplinary branch of science dealing with the structural and theoretical study of luminous and electromagnetic radiation (particularly within the ultraviolet and short-wave visible spectrum) and the chemical, photochemical, or biological effects they produce on exposed bodies. Actinology encompasses principles from optical physics, photochemistry, and biophysics to analyze how radiant fluxes interact with organic and inorganic matter.