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Scent
An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sense of smell. An odor is also called a "smell" or a "scent", which can refer to either a pleasant or an unpleasant odor. While "odor" and "smell" can refer to pleasant and unpleasant odors, the terms "scent", "aroma", and "fragrance" are usually reserved for pleasant-smelling odors and are frequently used in the food and cosmetic industry to describe floral scents or to refer to perfumes. Physiology of smell Sense of smell The perception of odors, or sense of smell, is mediated by the olfactory nerve. The olfactory receptor (OR) cells are neurons present in the olfactory epithelium, which is a small patch of tissue at the back of the nasal cavity. There are millions of olfactory receptor neurons that act as sensory signaling cells. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perfume
Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent. The 1939 Nobel Laureate for Chemistry, Leopold Ružička stated in 1945 that "right from the earliest days of scientific chemistry up to the present time, perfumes have substantially contributed to the development of organic chemistry as regards methods, systematic classification, and theory." Ancient texts and archaeological excavations show the use of perfumes in some of the earliest human civilizations. Modern perfumery began in the late 19th century with the commercial synthesis of aroma compounds such as vanillin or coumarin, which allowed for the composition of perfumes with smells previously unattainable solely from natural aromatics. History The word ''perfume'' derives from the Latin ''perfumare'', meaning "to smoke through". ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floral Scent
Floral scent, or flower scent, is composed of all the volatile organic compounds (VOCs), or aroma compounds, emitted by floral tissue (e.g. flower petals). Other names for floral scent include, aroma, fragrance, floral odour or perfume. Flower scent of most flowering plant species encompasses a diversity of VOCs, sometimes up to several hundred different compounds. The primary functions of floral scent are to deter herbivores and especially folivorous insects (see Plant defense against herbivory), and to attract pollinators. Floral scent is one of the most important communication channels mediating plant-pollinator interactions, along with visual cues (flower color, shape, etc.). Biotic interactions Perception by flower visitors Flower visitors such as insects and bats detect floral scents thanks to chemoreceptors of variable specificity to a specific VOC. The fixation of a VOC on a chemoreceptor triggers the activation of an antennal glomerulus, further projecting on an olfac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perceptions
Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system, which in turn result from physical or chemical stimulation of the sensory system.Goldstein (2009) pp. 5–7 Vision involves light striking the retina of the eye; smell is mediated by odor molecules; and hearing involves pressure waves. Perception is not only the passive receipt of these signals, but it is also shaped by the recipient's learning, memory, expectation, and attention. Gregory, Richard. "Perception" in Gregory, Zangwill (1987) pp. 598–601. Sensory input is a process that transforms this low-level information to higher-level information (e.g., extracts shapes for object recognition). The process that follows connects a person's concepts and expectations (or knowledge), restorative and selective mechanisms (such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sense Of Smell
The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste. In humans, it occurs when an odor binds to a olfactory receptor, receptor within the nasal cavity, transmitting a signal through the olfactory system. Glomerulus (olfaction), Glomeruli aggregate signals from these receptors and transmit them to the olfactory bulb, where the sensory input will start to interact with parts of the brain responsible for smell identification, memory, and emotion. There are many different causes for alteration, anosmia, lack, or disturbance to a normal sense of smell, and can include damage to the nose or smell receptors, or central problems affecting the brain. Some causes include Upper respiratory tract infection, upper respiratory infections, traumatic brain injury, and Neurodegeneration, neurodegenerative disease. Histo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the physical or chemical structure of an organism's internal or external environment. The ability of an organism or organ to detect external stimuli, so that an appropriate reaction can be made, is called sensitivity (excitability). Sensory receptors can receive information from outside the body, as in touch receptors found in the skin or light receptors in the eye, as well as from inside the body, as in chemoreceptors and mechanoreceptors. When a stimulus is detected by a sensory receptor, it can elicit a reflex via stimulus transduction. An internal stimulus is often the first component of a homeostatic control system. External stimuli are capable of producing systemic responses throughout the body, as in the fight-or-flight response. In order for a stimulus to be detected with high probability, its level of strength must exceed the absolute threshold; if a signal does reach threshold, the information is transmitted to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spengler
Spengler is a German-language occupational surname, literally meaning "metal worker" or " tin knocker". It may refer to: * Alexander Spengler (1827–1901), the first Davos doctor specializing in tuberculosis * Bruno Spengler (born 1983), a Canadian racecar driver * Egon Spengler, a character from the ''Ghostbusters'' films * John Spengler, the Akira Yamaguchi Professor of Environmental Health and Human Habitation at Harvard T.H. Chan School of Public Health * Jörg Spengler (born 1938), German sailor * Joseph J. Spengler (1912–1991), American economist, statistician and historian of economic thought * Lorenz Spengler (1720–1807), Swiss-born Danish decorative artist and naturalist * Oswald Spengler (1880–1936), German author, writer of ''The Decline of the West'' * Pierre Spengler, a European film producer * Volker Spengler (1939-2020), German actor * Spengler, pen name of David P. Goldman David Paul Goldman (born September 27, 1951) is an American economist, music critic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Sulfide
Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The underground mine gas term for foul-smelling hydrogen sulfide-rich gas mixtures is ''stinkdamp''. Swedish chemist Carl Wilhelm Scheele is credited with having discovered the chemical composition of purified hydrogen sulfide in 1777. The British English spelling of this compound is hydrogen sulphide, a spelling no longer recommended by the Royal Society of Chemistry or the International Union of Pure and Applied Chemistry. Hydrogen sulfide is toxic to humans and most other animals by inhibiting cellular respiration in a manner similar to hydrogen cyanide. When it is inhaled or it or its salts are ingested in high amounts, damage to organs occurs rapidly with symptoms ranging from breathing difficulties to convulsions and death. Despite this, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous waste, particularly among aquatic organisms, and it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to 45% of the world's food and fertilizers. Around 70% of ammonia is used to make fertilisers in various forms and composition, such as urea and Diammonium phosphate. Ammonia in pure form is also applied directly into the soil. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceutical products and is used in many commercial cleaning products. It is mainly collected by downward displacement of both air and water. Although common in nature—both terrestrially and in the outer planets of the Solar System—and in wide use, ammonia is both caust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jan Brueghel D
Jan, JaN or JAN may refer to: Acronyms * Jackson, Mississippi (Amtrak station), US, Amtrak station code JAN * Jackson-Evers International Airport, Mississippi, US, IATA code * Jabhat al-Nusra (JaN), a Syrian militant group * Japanese Article Number, a barcode standard compatible with EAN * Japanese Accepted Name, a Japanese nonproprietary drug name * Job Accommodation Network, US, for people with disabilities * ''Joint Army-Navy'', US standards for electronic color codes, etc. * '' Journal of Advanced Nursing'' Personal name * Jan (name), male variant of ''John'', female shortened form of ''Janet'' and ''Janice'' * Jan (Persian name), Persian word meaning 'life', 'soul', 'dear'; also used as a name * Ran (surname), romanized from Mandarin as Jan in Wade–Giles * Ján, Slovak name Other uses * January, as an abbreviation for the first month of the year in the Gregorian calendar * Jan (cards), a term in some card games when a player loses without taking any tricks or scoring ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Objectivity (science)
Objectivity in science is an attempt to uncover truths about the natural world by eliminating personal biases, emotions, and false beliefs. It is often linked to observation as part of the scientific method. It is thus intimately related to the aim of testability and reproducibility. To be considered objective, the results of measurement must be communicated from person to person, and then for third parties, as an advance in a collective understanding of the world. Such demonstrable knowledge has ordinarily conferred demonstrable powers of prediction or technology. The problem of philosophical objectivity is contrasted with personal subjectivity, sometimes exacerbated by the overgeneralization of a hypothesis to the whole. For example, Newton's law of universal gravitation appears to be the norm for the attraction between celestial bodies, but it was later refined and extended—and philosophically superseded—by the more general theory of relativity. History The scientific m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analytical Technique
Analytical technique is a method used to determine a chemical or physical property of a chemical substance, chemical element, or mixture. There is a wide variety of techniques used for analysis, from simple weighing to advanced techniques using highly specialized instrumentation. Classical methods of analysis Classical analysis methods involve basic analytical methods widely used in laboratories. Gravimetric analysis measures the weight of the sample. Titration, Titrimetry is a technique used to determine the concentration of the analyte. Spectrochemical analysis Spectrometer can determine chemical composition through its measure of spectrums. The common spectrometer used in analytical chemistry is Mass spectrometry. In a mass spectrometer, a small amount of sample is ionized and converted to gaseous ions, where they are separated and analyzed according to their Mass-to-charge ratio, mass-to-charge ratios. Electroanalytical analysis Electroanalytical method, Electroanalytical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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