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৪ নং লাইন:
{{distinguish|Inflorescence}}
{{
{{Use dmy dates|date=July 2012}}
[[Image:Fluorescent minerals hg.jpg|thumb|right|Fluorescent minerals emit visible light when exposed to [[ultraviolet]] light.]]
১৭ নং লাইন:
[[File:Lignum nephriticum - cup of Philippine lignum nephriticum, Pterocarpus indicus, and flask containing its fluorescent solution Hi.jpg|thumb|left|upright|''[[Lignum nephriticum]]'' cup made from the wood of the narra tree (''[[Pterocarpus indicus]]''), and a flask containing its fluorescent [[Solution (chemistry)|solution]]]]
[[File:Matlaline structure.svg|thumb|right|Matlaline, the fluorescent substance in the wood of the tree ''Eysenhardtia polystachya'']]
An early observation of fluorescence was described in 1560 by [[Bernardino de Sahagún]] and in 1565 by [[Nicolás Monardes]] in the [[infusion]] known as ''[[lignum nephriticum]]'' ([[Latin]] for "kidney wood"). It was derived from the wood of two tree species, ''[[Pterocarpus indicus]]'' and ''[[Eysenhardtia polystachya]]''.<ref name="acuna">{{
In 1819, [[Edward Daniel Clarke|Edward D. Clarke]]<ref>{{
In his 1852 paper on the "Refrangibility" ([[wavelength]] change) of light, [[George Gabriel Stokes]] described the ability of [[fluorite|fluorspar]] and [[uranium glass]] to change invisible light beyond the violet end of the visible spectrum into blue light. He named this phenomenon ''fluorescence'' : "I am almost inclined to coin a word, and call the appearance ''fluorescence'', from fluor-spar [i.e., fluorite], as the analogous term ''opalescence'' is derived from the name of a mineral."<ref>{{
|title = On the Change of Refrangibility of Light
|author = Stokes, G. G.
৯৯ নং লাইন:
===Fluorence===
Strongly fluorescent pigments often have an unusual appearance which is often described colloquially as a "neon color." This phenomenon was termed "Farbenglut" by [[Hermann von Helmholtz]] and "fluorence" by Ralph M. Evans. It is generally thought to be related to the high brightness of the color relative to what it would be as a component of white. Fluorescence shifts energy in the incident illumination from shorter wavelengths to longer (such as blue to yellow) and thus can make the fluorescent color appear brighter (more saturated) than it could possibly be by reflection alone.<ref>{{
==Rules==
১১১ নং লাইন:
===Stokes shift===
{{
In general, emitted fluorescent light has a longer wavelength and lower energy than the absorbed light.<ref>[[#Lakowicz|Lakowicz]], pp. 6–7</ref> This phenomenon, known as [[Stokes shift]], is due to energy loss between the time a photon is absorbed and when it is emitted. The causes and magnitude of Stokes shift can be complex and are dependent on the fluorophore and its environment. However, there are some common causes. It is frequently due to non-radiative decay to the lowest vibrational energy level of the excited state. Another factor is that the emission of fluorescence frequently leaves a fluorophore in a higher vibrational level of the ground state.
১২০ নং লাইন:
====Biofluorescence====
Biofluorescence is the absorption of [[electromagnetic radiation|electromagnetic]] wavelengths from the [[visible light]] spectrum by fluorescent proteins in a living organism, and the reemission of that light at a lower energy level. This causes the light that is re-emitted to be a different color than the light that is absorbed. Stimulating light excites an [[electron]], raising energy to an unstable level. This instability is unfavorable, so the energized electron is returned to a stable state almost as immediately as it becomes unstable. This return to stability corresponds with the release of excess energy in the form of fluorescent light. This emission of light is only observable when the stimulant light is still providing light to the organism/object and is typically yellow, pink, orange, red, green, or purple. Biofluorescence is often confused with the following forms of biotic light, bioluminescence and biophosphorescence.<ref name="Fluorescence in marine organisms">{{
====Bioluminescence====
১৩১ নং লাইন:
====Epidermal chromatophores====
Pigment cells that exhibit fluorescence are called fluorescent chromatophores, and function somatically similar to regular [[chromatophore]]s. These cells are dendritic, and contain pigments called fluorosomes. These pigments contain fluorescent proteins which are activated by K+ (potassium) ions, and it is their movement, aggregation, and dispersion within the fluorescent chromatophore that cause directed fluorescence patterning.<ref name="wucherer" /><ref>{{
| pmid = 11041206
| year = 2000
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}}</ref> Fluorescent cells are innervated the same as other chromatphores, like melanophores, pigment cells that contain [[melanin]]. Short term fluorescent patterning and signaling is controlled by the nervous system.<ref name ="wucherer" /> Fluorescent chromatophores can be found in the skin (e.g. in fish) just below the epidermis, amongst other chromatophores.
Epidermal fluorescent cells in fish also respond to hormonal stimuli by the α–MSH and MCH hormones much the same as melanophores. This suggests that fluorescent cells may have color changes throughout the day that coincide with their [[circadian rhythm]].<ref>{{
===Phylogenetics===
====Evolutionary origins====
It is suspected by some scientists that [[Green fluorescent protein|GFPs]] and GFP like proteins began as electron donors activated by light. These electrons were then used for reactions requiring light energy. Functions of fluorescent proteins, such as protection from the sun, conversion of light into different wavelengths, or for signaling are thought to have evolved secondarily.<ref name="Biology of underwater fluorescence">{{
[[File:Observed occurrences of green and red biofluorescence in Actinopterygii - journal.pone.0083259.g002.png|thumb|Observed occurrences of green and red biofluorescence in Actinopterygii – journal.pone.0083259.g002|thumb|Fluorescence has multiple origins in the tree of life. This diagram displays the origins within actinopterygians (ray finned fish).]]
The incidence of fluorescence across the [[tree of life]] is widespread, and has been studied most extensively in a phylogenetic sense in fish. The phenomenon appears to have evolved multiple times in multiple [[tax]]a such as in the anguilliformes (eels), gobioidei (gobies and cardinalfishes), and tetradontiformes (triggerfishes), along with the other taxa discussed later in the article. Fluorescence is highly genotypically and phenotypically variable even within ecosystems, in regards to the wavelengths emitted, the patterns displayed, and the intensity of the fluorescence. Generally, the species relying upon camouflage exhibit the greatest diversity in fluorescence, likely because camouflage is one of the most common uses of fluorescence.<ref name="sparks">{{
====Adaptive functions====
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Water absorbs light of long wavelengths, so less light from these wavelengths reflects back to reach the eye. Therefore, warm colors from the visual light spectrum appear less vibrant at increasing depths. Water scatters light of shorter wavelengths, meaning cooler colors dominate the visual field in the [[photic zone]]. Light intensity decreases 10 fold with every 75 m of depth, so at depths of 75 m, light is 10% as intense as it is on the surface, and is only 1% as intense at 150 m as it is on the surface. Because the water filters out the wavelengths and intensity of water reaching certain depths, different proteins, because of the wavelengths and intensities of light they are capable of absorbing, are better suited to different depths. Theoretically, some fish eyes can detect light as deep as 1000 m. At these depths of the aphotic zone, the only sources of light are organisms themselves, giving off light through chemical reactions in a process called bioluminescence.
Fluorescence is simply defined as the absorption of electromagnetic radiation at one [[wavelength]] and its reemission at another, lower energy wavelength.<ref name="sparks" /> Thus any type of fluorescence depends on the presence of external sources of light. Biologically functional fluorescence is found in the photic zone, where there is not only enough light to cause biofluorescence, but enough light for other organisms to detect it. The visual field in the photic zone is naturally blue, so colors of fluorescence can be detected as bright reds, oranges, yellows, and greens. Green is the most commonly found color in the biofluorescent spectrum, yellow the second most, orange the third, and red is the rarest. Fluorescence can occur in organisms in the aphotic zone as a byproduct of that same organism’s bioluminescence. Some biofluorescence in the aphotic zone is merely a byproduct of the organism’s tissue biochemistry and does not have a functional purpose. However, some cases of functional and adaptive significance of biofluorescence in the aphotic zone of the deep ocean is an active area of research.<ref>{{
====[[Photic zone]]====
১৬৯ নং লাইন:
Bony fishes living in shallow water, due to living in a colorful environment, generally have good color vision. Thus, in shallow-water fishes, red, orange, and green fluorescence most likely serves as a means of communication with conspecifics, especially given the great phenotypic variance of the phenomenon.<ref name="sparks"/>
Many fish that exhibit biofluorescence, such as [[sharks]], [[lizardfish]], [[scorpionfish]], [[wrasses]], and [[flatfishes]], also possess yellow intraocular filters.<ref name="Heinermann">{{
Another adaptive use of fluorescence is to generate red light from the ambient blue light of the [[photic zone]] to aid vision. Red light can only be seen across short distances due to attenuation of red light wavelengths by water.<ref name="michiels">{{
| pmid = 24870049
| pmc = 4071555
১৯২ নং লাইন:
=====Coral=====
Fluorescence serves a wide variety of functions in coral. Fluorescent proteins in corals may contribute to photosynthesis by converting otherwise unusable wavelengths of light into ones for which the coral’s symbiotic algae are able to conduct [[photosynthesis]].<ref>{{
=====[[Cephalopods]]=====
''Alloteuthis subulata'' and ''Loligo vulgaris'', two types of nearly transparent squid, have fluorescent spots above their eyes. These spots reflect incident light, which may serve as a means of camouflage, but also for signaling to other squids for schooling purposes.<ref>{{
|pmid = 11441052
|url = http://jeb.biologists.org/content/204/12/2103.short
২১৮ নং লাইন:
[[File:Crystal Jelly ("Aequorea Victoria"), Monterey Bay Aquarium, Monterey, California, USA.jpg|thumb|DSC26479, Crystal Jelly ("Aequorea Victoria"), Monterey Bay Aquarium, Monterey, California, USA (5085398602)|thumb|''Aequoria victoria'', biofluorescent jellyfish known for GFP]]
Another, well-studied example of biofluorescence in the ocean is the [[hydrozoan]] ''[[Aequorea victoria]]''. This jellyfish lives in the photic zone off the west coast of North America and was identified as a carrier of [[green fluorescent protein]] (GFP) by [[Osamu Shimomura]]. The gene for these green fluorescent proteins has been isolated and is scientifically significant because it is widely used in genetic studies to indicate the expression of other genes.<ref>{{
=====Mantis shrimp=====
Several species of [[mantis shrimp]], which are stomatopod [[crustaceans]], including ''Lysiosquillina glabriuscula'', have yellow fluorescent markings along their antennal scales and [[carapace]] (shell) that males present during threat displays to predators and other males. The display involves raising the head and thorax, spreading the striking appendages and other maxillipeds, and extending the prominent, oval antennal scales laterally, which makes the animal appear larger and accentuates its yellow fluorescent markings. Furthermore, as depth increases, mantis shrimp fluorescence accounts for a greater part of the visible light available. During mating rituals, mantis shrimp actively fluoresce, and the wavelength of this fluorescence matches the wavelengths detected by their eye pigments.<ref>{{
====[[Aphotic zone]]====
=====Siphonophores=====
''[[Siphonophorae]]'' is an order of marine animals from the phylum [[Hydrozoa]] that consist of a specialized [[jellyfish|medusoid]] and [[polyp]] [[zooid]]. Some siphonophores, including the genus Erenna that live in the aphotic zone between depths of 1600 m and 2300 m, exhibit yellow to red fluorescence in the [[photophores]] of their tentacle-like [[tentilla]]. This fluorescence occurs as a by-product of bioluminescence from these same photophores. The siphonophores exhibit the fluorescence in a flicking pattern that is used as a lure to attract prey.<ref>{{
| doi = 10.1016/j.bbagen.2006.08.014
| title = Quenching of superoxide radicals by green fluorescent protein
২৪২ নং লাইন:
=====Dragonfish=====
The predatory deep-sea [[Barbeled dragonfish|dragonfish]] ''Malacosteus niger'', the closely related ''Aristostomias'' genus and the species ''Pachystomias microdon'' are capable of harnessing the blue light emitted from their own bioluminescence to generate red biofluorescence from suborbital [[photophores]]. This red fluorescence is invisible to other animals, which allows these dragonfish extra light at dark ocean depths without attracting or signaling predators.<ref>{{
===Terrestrial biofluorescence===
====Amphibians====
The [[Polka-dot tree frog]], widely found in the [[Amazon rainforest|Amazon]] was discovered to be the first fluorescent [[amphibian]] in 2017. The frog is pale green with dots in white, yellow or light red. The fluorescence of the frog was discovered unintentionally in Buenos Aires, Argentina. The fluorescence was traced to a new compound found in the [[lymph]] and skin glads.<ref>{{
====Butterflies====
[[swallowtail butterfly|Swallowtail]] (''Papilio'') butterflies have complex systems for emitting fluorescent light. Their wings contain pigment-infused crystals that provide directed fluorescent light. These crystals function to produce fluorescent light best when they absorb [[radiance]] from sky-blue light (wavelength about 420 nm). The wavelengths of light that the butterflies see the best correspond to the absorbance of the crystals in the butterfly's wings. This likely functions to enhance the capacity for signaling.<ref>{{
| pmid = 16293753
| year = 2005
২৬৬ নং লাইন:
====Parrots====
[[Parrots]] have fluorescent [[plumage]] that may be used in mate signaling. A study using mate-choice experiments on [[budgerigars]] (''Melopsittacus undulates'') found compelling support for fluorescent sexual signaling, with both males and females significantly preferring birds with the fluorescent experimental stimulus. This study suggests that the fluorescent plumage of parrots is not simply a by-product of [[pigmentation]], but instead an adapted sexual signal. Considering the intricacies of the pathways that produce fluorescent pigments, there may be significant costs involved. Therefore, individuals exhibiting strong fluorescence may be honest indicators of high individual quality, since they can deal with the associated costs.<ref>{{
====Arachnids====
[[File:Sorpion Under Blacklight edit.jpg|thumb|Fluorescing scorpion]]
Spiders fluoresce under UV light and possess a huge diversity of fluorophores. Remarkably, spiders are the only known group in which fluorescence is “taxonomically widespread, variably expressed, evolutionarily labile, and probably under selection and potentially of ecological importance for intraspecific and interspecific signaling.” A study by Andrews et al. (2007) reveals that fluorescence has evolved multiple times across spider taxa, with novel fluorophores evolving during spider diversification. In some spiders, ultraviolet cues are important for predator-prey interactions, intraspecific communication, and camouflaging with matching fluorescent flowers. Differing ecological contexts could favor inhibition or enhancement of fluorescence expression, depending upon whether fluorescence helps spiders be cryptic or makes them more conspicuous to predators. Therefore, natural selection could be acting on expression of fluorescence across spider species.<ref>{{
| pmid = 17412670
| pmc = 2104643
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}}</ref>
Scorpions also fluoresce.<ref>{{
====Plants====
The ''Mirabilis jalapa'' flower contains violet, fluorescent betacyanins and yellow, fluorescent betaxanthins. Under white light, parts of the flower containing only betaxanthins appear yellow, but in areas where both betaxanthins and betacyanins are present, the visible fluorescence of the flower is faded due to internal light-filtering mechanisms. Fluorescence was previously suggested to play a role in [[pollinator]] attraction, however, it was later found that the visual signal by fluorescence is negligible compared to the visual signal of light reflected by the flower.<ref>{{
[[Chlorophyll]] fluoresces a weak red under ultraviolet light.<ref>{{
===Abiotic fluorescence===
৩১৪ নং লাইন:
====Atmosphere====
Fluorescence is observed in the atmosphere when the air is under energetic electron bombardment. In cases such as the natural [[aurora]], high-altitude nuclear explosions, and rocket-borne electron gun experiments, the molecules and ions formed have a fluorescent response to light.<ref name=gilmore1992>
{{
====Common materials that fluoresce====
৩২৫ নং লাইন:
===Lighting===
{{
[[Image:Www Beo cc.jpg|thumb|Fluorescent paint and plastic lit by [[UV tube]]s. Paintings by Beo Beyond]]
The common [[fluorescent lamp]] relies on fluorescence. Inside the [[glass]] tube is a partial vacuum and a small amount of [[mercury (element)|mercury]]. An electric discharge in the tube causes the mercury atoms to emit mostly ultraviolet light. The tube is lined with a coating of a fluorescent material, called the ''[[phosphor]]'', which absorbs the ultraviolet and re-emits visible light. Fluorescent [[lighting]] is more energy-efficient than [[incandescent]] lighting elements. However, the uneven [[spectrum]] of traditional fluorescent lamps may cause certain colors to appear different than when illuminated by incandescent light or [[daylight]]. The mercury vapor emission spectrum is dominated by a short-wave UV line at 254 nm (which provides most of the energy to the phosphors), accompanied by visible light emission at 436 nm (blue), 546 nm (green) and 579 nm (yellow-orange). These three lines can be observed superimposed on the white continuum using a hand spectroscope, for light emitted by the usual white fluorescent tubes. These same visible lines, accompanied by the emission lines of trivalent europium and trivalent terbium, and further accompanied by the emission continuum of divalent europium in the blue region, comprise the more discontinuous light emission of the modern trichromatic phosphor systems used in many [[compact fluorescent lamp]] and traditional lamps where better color rendition is a goal.<ref name="How Fluorescent Lamps Work">{{
Fluorescent lights were first available to the public at the [[1939 New York World's Fair]]. Improvements since then have largely been better phosphors, longer life, and more consistent internal discharge, and easier-to-use shapes (such as compact fluorescent lamps). Some [[High-intensity discharge lamp|high-intensity discharge (HID) lamps]] couple their even-greater electrical efficiency with phosphor enhancement for better color rendition.{{Citation needed|date=July 2010}}
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===Analytical chemistry===
Many analytical procedures involve the use of a [[fluorometer]], usually with a single exciting wavelength and single detection wavelength. Because of the sensitivity that the method affords, fluorescent molecule concentrations as low as 1 part per trillion can be measured.<ref>{{
Fluorescence in several wavelengths can be detected by an [[Chromatography detector|array detector]], to detect compounds from [[High-performance liquid chromatography|HPLC]] flow. Also, [[Thin layer chromatography|TLC]] plates can be visualized if the compounds or a coloring reagent is fluorescent. Fluorescence is most effective when there is a larger ratio of atoms at lower energy levels in a [[Boltzmann distribution]]. There is, then, a higher probability of excitement and release of photons by lower-energy atoms, making analysis more efficient.
===Spectroscopy===
{{
Usually the setup of a fluorescence assay involves a light source, which may emit many different wavelengths of light. In general, a single wavelength is required for proper analysis, so, in order to selectively filter the light, it is passed through an excitation monochromator, and then that chosen wavelength is passed through the sample cell. After absorption and re-emission of the energy, many wavelengths may emerge due to [[Stokes shift]] and various [[electron transition]]s. To separate and analyze them, the fluorescent radiation is passed through an emission [[monochromator]], and observed selectively by a detector.<ref>{{
===Biochemistry and medicine===
{{
[[Image:FluorescentCells.jpg|thumb|right|[[Endothelium|Endothelial cells]] under the microscope with three separate channels marking specific cellular components]]
Fluorescence in the life sciences is used generally as a non-destructive way of tracking or analysis of biological molecules by means of the fluorescent emission at a specific frequency where there is no background from the excitation light, as relatively few cellular components are naturally fluorescent (called intrinsic or [[autofluorescence]]).
৩৬৫ নং লাইন:
* DNA detection: the compound [[ethidium bromide]], in aqueous solution, has very little fluorescence, as it is quenched by water. Ethidium bromide's fluorescence is greatly enhanced after it binds to DNA, so this compound is very useful in visualising the location of DNA fragments in [[agarose gel electrophoresis]]. Intercalated ethidium is in a hydrophobic environment when it is between the base pairs of the DNA, protected from quenching by water which is excluded from the local environment of the intercalated ethidium. Ethidium bromide may be carcinogenic – an arguably safer alternative is the dye [[SYBR Green]].
* FIGS ([[Fluorescence image-guided surgery]]) is a medical imaging technique that uses fluorescence to detect properly labeled structures during surgery.
* [[Intravascular fluorescence]] is a catheter-based medical imaging technique that uses fluorescence to detect high-risk features of atherosclerosis and unhealed vascular stent devices.<ref name="pmid20210433">{{
* SAFI (species altered fluorescence imaging) an imaging technique in [[electrokinetic phenomena|electrokinetics]] and [[microfluidics]].<ref>{{
|pmid = 23463253
|url = https://microfluidics.stanford.edu/Publications/ParticleTracking_Diagnostics/Shkolnikov_A%20method%20for%20non-invasive%20full-field%20imaging%20and%20quantification%20of%20chemical%20species.pdf
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|df = dmy-all
}}</ref> It uses non-electromigrating dyes whose fluorescence is easily quenched by migrating chemical species of interest. The dye(s) are usually seeded everywhere in the flow and differential quenching of their fluorescence by analytes is directly observed.
* Fluorescence-based assays for screening [[Toxicity|toxic]] chemicals. The optical assays consist of a mixture of environmental-sensitive fluorescent dyes and human skin cells that generate fluorescence spectra patterns.<ref name="Moczko2016">{{
| pmid = 27653274
| pmc = 5031998
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===Optical brighteners===
{{
Fluorescent compounds are often used to enhance the appearance of fabric and paper, causing a "whitening" effect. A white surface treated with an optical brightener can emit more visible light than that which shines on it, making it appear brighter. The blue light emitted by the brightener compensates for the diminishing blue of the treated material and changes the hue away from yellow or brown and toward white. Optical brighteners are used in laundry detergents, high brightness paper, cosmetics, [[high-visibility clothing]] and more.
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==References==
{{
==Bibliography==
* {{
==External links==
{{
* [http://www.fluorophores.org Fluorophores.org], the database of fluorescent dyes
* [http://micro.magnet.fsu.edu/primer/techniques/fluorescence/fluorescenceintro.html FSU.edu], Basic Concepts in Fluorescence
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