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Odor intensity can be expressed using an odor intensity scale, which is a verbal description of an odor sensation to which a numerical value is assigned. [31] Odor intensity can be divided into the following categories according to intensity: 0 – no odor 1 – very weak (odor threshold) 2 – weak 3 – distinct 4 – strong 5 – very strong
Smog, or smoke fog, is a type of intense air pollution.The word "smog" was coined in the early 20th century, and is a portmanteau of the words smoke and fog [1] to refer to smoky fog due to its opacity, and odour. [2]
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
The Lady and the Unicorn, a Flemish tapestry depicting the sense of smell, 1484–1500. Musée national du Moyen Âge, Paris.. Early scientific study of the sense of smell includes the extensive doctoral dissertation of Eleanor Gamble, published in 1898, which compared olfactory to other stimulus modalities, and implied that smell had a lower intensity discrimination.
Geosmin (/ dʒ i ˈ ɒ z m ɪ n / jee-OZ-min) is an irregular sesquiterpenoid with a distinct earthy or musty odor, which most people can easily smell. The geosmin odor detection threshold in humans is very low, ranging from 0.006 to 0.01 micrograms per liter in water. [1]
Among over a thousand persons aged 40 years and older, 12.0% reported a problem with smell in the past 12 months and 12.4% had olfactory dysfunction on examination. Prevalence rose from 4.2% at age 40–49 to 39.4% at 80 years and older and was higher in men than women, in blacks and Mexican Americans than in whites and in less than more educated.
The OFC further projects to the anterior cingulate cortex where it plays a role in appetite. [29] The OFC also associates odors with other stimuli, such as taste. [25] Odor perception and discrimination also involve the OFC. The spatial odor map in the glomeruli layer of the olfactory bulb may contribute to these functions.
The pyrophosphate ester of farnesol is the building blocks of possibly all acyclic sesquiterpenoids. These compounds are doubled to form 30-carbon squalene, which is the precursor for steroids in plants, animals, and fungi.