In atomic physics , a partial charge (or net atomic charge ) is a non- integer charge value when measured in elementary charge units. It is represented by the Greek lowercase delta (𝛿), namely 𝛿− or 𝛿+.
21-534: OTV may refer to: Odor threshold value , a measure of odor intensity Orbital Test Vehicle, another name for the Boeing X-37 uncrewed spacecraft Orbital transfer vehicle , a space tug used to move a spacecraft from one orbit to another Outer Tactical Vest, a part of the Interceptor Body Armor system Overlay transport virtualization ,
42-422: A Russian TV channel Oceania Television Network , a Palauan TV channel Other [ edit ] Omnium de Traitement et de Valorisation , a subsidiary of Veolia Environnement One True Voice , a British boyband Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title OTV . If an internal link led you here, you may wish to change
63-691: A computer networking protocol Ozone tagging velocimetry, a modified hydroxyl tagging velocimetry TV networks, channels, stations and companies [ edit ] OfflineTV , an American online media collective based in Los Angeles , California OTV (Romanian TV channel) , a defunct television station in Bucharest, Romania Okinawa Television , part of the Fuji News Network in Japan OTV (Egyptian TV channel) (2007–2011),
84-487: A food is dependent upon: The concentration of an odor above a food is dependent on its solubility in that food and its vapor pressure and concentration in that food. A 2014 study found no significant differences between men and women, and between non-pregnant and pregnant individuals, despite the existence of anecdotal reports of hyperosmia among the latter. People with Multiple Sclerosis have been found to have higher olfactory thresholds. In scientific research, this
105-583: A former television station in Egypt Odisha TV , TV stations owned by Ortel Communications Ltd., Bhubaneswar, Odisha OTV (Lebanon) , a Lebanese television station Otvorena televizija , former name of Jabuka TV , a TV station in Zagreb, Croatia OTV (Ukrainian TV channel) , Ukrainian music TV channel OTV (Turkish TV channel) , Turkish music TV channel OTV (Croatian TV channel) , Croatian music TV channel OTV (Russian TV channel) ,
126-447: A given compound can be derived in multiple ways, such as: The discussion of individual compounds in prior work has shown convergence in atomic charges, i.e., a high level of consistency between the assigned degree of polarity and the physical-chemical properties mentioned above. The resulting uncertainty in atomic charges is ±0.1e to ±0.2e for highly charged compounds, and often <0.1e for compounds with atomic charges below ±1.0e. Often,
147-446: A group always carries a whole number of elementary charge units. Yet one can point to zones within the assemblage where less than a full charge resides, such as the area around an atom's nucleus. This is possible in part because particles are not like mathematical points—which must be either inside a zone or outside it—but are smeared out by the uncertainty principle of quantum mechanics . Because of this smearing effect, if one defines
168-581: A mathematical limit as the basis set is improved towards completeness. Hirshfeld partial charges are usually too low in magnitude. Some methods for assigning partial atomic charges do not converge to a unique solution. In some materials, atoms in molecules analysis yields non-nuclear attractors describing electron density partitions that cannot be assigned to any atom in the material; in such cases, atoms in molecules analysis cannot assign partial atomic charges. According to Cramer (2002), partial charge methods can be divided into four classes: The following
189-415: A small space surrounding the nucleus of an atom : When an electrically neutral atom bonds chemically to another neutral atom that is more electronegative , its electrons are partially drawn away. This leaves the region about that atom's nucleus with a partial positive charge, and it creates a partial negative charge on the atom to which it is bonded. In such a situation, the distributed charges taken as
210-439: A substance that can be detected by a human nose . Some substances can be detected when their concentration is only few milligrams per 1000 tonnes , which is less than a drop in an Olympic swimming pool . Odor threshold value can be expressed as a concentration in water or concentration in air. Two major types of flavor thresholds can be distinguished: the absolute and the difference threshold. The odor detection threshold and
231-400: A sufficiently small zone, a fundamental particle may be both partly inside and partly outside it. Partial atomic charges are used in molecular mechanics force fields to compute the electrostatic interaction energy using Coulomb's law , even though this leads to substantial failures for anisotropic charge distributions. Partial charges are also often used for a qualitative understanding of
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#1732779589134252-433: Is often represented by a lower threshold score , i.e. reversing the scale. Olfactory function is more impaired in patients with primary progressive MS than that in relapsing-remitting MS. Some species can detect odors that others cannot. It is widely believed that animals such as dogs and rodents have a superior sense of smell overall, however a 2017 paper disputed that, saying that "the absolute number of olfactory neurons
273-441: Is remarkably consistent across mammals". Partial charge Partial charges are created due to the asymmetric distribution of electrons in chemical bonds . For example, in a polar covalent bond like HCl , the shared electron oscillates between the bonded atoms. The resulting partial charges are a property only of zones within the distribution, and not the assemblage as a whole. For example, chemists often choose to look at
294-492: The application of one or two of the above concepts already leads to very good values, especially taking into account a growing library of experimental benchmark compounds and compounds with tested force fields. The published research literature on partial atomic charges varies in quality from extremely poor to extremely well-done. Although a large number of different methods for assigning partial atomic charges from quantum chemistry calculations have been proposed over many decades,
315-399: The degree of ionic versus covalent bonding of any compound across the periodic table. The necessity for such quantities arises, for example, in molecular simulations to compute bulk and surface properties in agreement with experiment. Evidence for chemically different compounds shows that available experimental data and chemical understanding lead to justified atomic charges. Atomic charges for
336-484: The human nose. It is only in recent years that such compounds were separated on gas chromatographs . For raw water treatment and waste water management, the term commonly used is Threshold Odor Number (TON). For instance, the water to be supplied for domestic use in Illinois is 3 TON. Odor threshold value (OTV) (also aroma threshold value (ATV) , Flavor threshold ) is defined as the most minimal concentration of
357-399: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=OTV&oldid=1255876670 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Odor threshold value The odor detection threshold is
378-626: The lowest concentration of a certain odor compound that is perceivable by the human sense of smell . The threshold of a chemical compound is determined in part by its shape , polarity , partial charges , and molecular mass . The olfactory mechanisms responsible for a compound's different detection threshold is not well understood. As such, odor thresholds cannot be accurately predicted. Rather, they must be measured through extensive tests using human subjects in laboratory settings. Optical isomers can have different detection thresholds because their conformations may cause them to be less perceivable for
399-420: The odor recognition threshold are absolute thresholds; the first is the minimum concentration at which an odor can be detected without any requirements to identify or recognize the stimulus, while the second is the minimum concentration at which a stimulus can be identified or recognized. The odor threshold value of an odorant is influenced by the medium. Examples of substances with strong odors: Threshold in
420-432: The structure and reactivity of molecules. Occasionally, δδ+ is used to indicate a partial charge that is less positively charged than δ+ (likewise for δδ-) in cases where it is relevant to do so. This can be extended to δδδ+ to indicate even weaker partial charges as well. Generally, a single δ+ (or δ-) is sufficient for most discussions of partial charge in organic chemistry. Partial atomic charges can be used to quantify
441-516: The vast majority of proposed methods do not work well across a wide variety of material types. Only as recently as 2016 was a method for theoretically computing partial atomic charges developed that performs consistently well across an extremely wide variety of material types. All of the earlier methods had fundamental deficiencies that prevented them from assigning accurate partial atomic charges in many materials. Mulliken and Löwdin partial charges are physically unreasonable, because they do not have
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