Fluorescent paint and its application, application and manufacturing features. Cold Light: The Physics of Luminescence
Infection caused by a dermatophyte fungus is called lichen. Microscopic organisms live on the skin, namely in the hair follicles. The fungus responsible for ringworm is found in the soil, which is why cats and large cattle are most often infected. Controversy persists environment up to two years even garden tools, shoes, carpet paths.
Children who try everything with their hands, and sometimes with their teeth, are exposed to infection due to weak immune system. The disease is transmitted to humans through domestic animals or from an infected environment. Athlete's foot and groin most often spread in public locker rooms and swimming pools.
Ringworm manifests itself small defeat with scaly skin in the center. Gradually, it grows, causing hair loss. The lesions are not always round, and the hair does not always fall out completely. Baldness can be accompanied by redness and inflammation. Hair can grow even during the presence of an infection on the body, so the disappearance of bald spots does not indicate a cure.
More accurate methods are required for diagnosis. Dermatologists often study pathological changes in the skin under the Wood's lamp to choose a further direction of examinations or to confirm their own guesses.
fluorescent lamp
The Wood's lamp is a diagnostic tool in which the affected skin, under the influence of black light, causes a certain glow. Black light is invisible to the naked eye waves in the ultraviolet spectrum, which glow purple in the dark.
The traditional Woods lamp was equipped with a mercury coating for 320-450 nm radiation and was invented in 1903 by physicist Robert Wood. Modern black light sources are developed on the basis of fluorescent, mercury, light-emitting lamps, diodes or incandescent lamps. It is the dark blue coating on the tube that filters out most of the visible light waves.
Luminescent diagnostics
To diagnose skin problems under the Wood's lamp, you need to follow a few steps:
- Wash the skin, remove make-up, moisturizers and other cosmetics, as it can cause a false positive result.
- Turn on the lamp to warm up for a minute.
- Turn off the lights in the office and curtain the windows to create darkness.
- When the vision adapts to the darkness, direct the light of the lamp to the skin at a distance of 10-30 cm.
The fluorescent color allows you to detect pigmented or depigmented spots.
Normal healthy skin glows light blue color, thickened areas appear white, oily areas appear yellow, and dehydrated skin turns purple.
To distinguish lichen contagious from other skin lesions, a Wood's lamp is used. The test result is positive if the pigmentation becomes more pronounced during the test.
Glow Features
Fluorescent black becomes visible when collagen or porphyrins absorb it and emit it in the visible spectrum. Threads, hair, preparation, and soap residue on the skin may also fluoresce.
What color does lichen glow under ultraviolet light for various skin pathologies:
- Increased pigmentation (melasma, post-inflammatory pigmentation). The lesions have clear boundaries under the light of the lamp due to an increase in the level of melanin in the cells.
- Loss of pigmentation (vitiligo, tuberous sclerosis, hypomelanosis) should be detected in fair-skinned people. The lesions will glow bright blue (sometimes yellowish green) due to the accumulation of biopterins. Areas with reduced blood flow do not change under light.
- Pityriasis versicolor is a mildly scaly persistent rash on the front of the chest and back caused by fungi. Under the light, the lamps glow orange or yellow. Pityriasis versicolor breaks pigmentation under the action of the fungus, and its spots become more pronounced under ultraviolet light.
- In folliculitis caused by the yeast Malassezia, the hair follicles emit a bluish-white light.
- Glow with ringworm depends on the type of fungal infection: with microsporia it is blue-green (M canis, M. audouinii, M distortum), and with trichophytosis it is pale blue. Fungal infections caused by other organisms do not fluoresce
- Erythrasma, caused by corynebacteria, is accompanied by a pigmented rash in skin folds that turn coral pink.
- Lichen planus is diagnosed by the appearance of whitish-yellow spots.
- Pink and herpes zoster are examined with a Wood's lamp for differential diagnosis only. The herpes virus is confirmed by the detection of DNA by the polymerase chain reaction method in the liquid, which is taken from the vesicles of the rash. Inflammatory processes are highlighted in white, which can also indicate an immune response to viruses or bacteria.
Wood's lamp directs diagnostics in the right direction. The most contagious type of fungus that causes lichen is microsporum. To confirm infection, bakposev is carried out in laboratory conditions requiring at least 10-14 days. Therefore, as a method of express diagnostics, Fluorescent Lamp with a Wood filter.
Fresh lesions of ringworm on the hair may not be detected with a lamp, because the signs of damage are minor. The dermatologist recommends that hair be removed from the suspected site of infection in order to examine the roots. Even after the death of the fungus, the hair continues to glow.
Diagnostic Rules
Wood's lamp helps to identify foci of lichen on smooth skin, hair, nails, eyebrows. Dermatologist uses protective mask or goggles to protect your eyes from the direct radiation of the lamp. The patient will be asked to close their eyes. The procedure lasts an average of 1-2 minutes, does not require additional actions on the part of the patient. Sometimes a microscope is used to detailed study skin conditions.
It must be remembered that a fluorescent examination only supplements the basic diagnosis, allows you to suspect a certain disease.
So a glowing white focus means inflammation, vitiligo, candidiasis, systemic lupus erythematosus. Therefore, differential diagnosis requires taking a scraping and analyzing the material under a microscope.
The experienced eye of a dermatologist is able to identify the shade of a particular pathology. At home, the Wood's lamp can refute or confirm the need to see a doctor when a rash appears on the body or head.
UV treatment
If fungal infections can be diagnosed with ultraviolet lamps, then other skin lesions are amenable to physiotherapy of the same name. The herpes virus that causes shingles is sensitive to ultraviolet light. Therefore, dermatologists use physiotherapy procedures that contribute to the gradual disappearance of spots. Pink lichen can be cured on its own, even in a solarium, if it does not respond to therapy and is prone to relapse.
Few people know, but a grandiose light show is constantly happening around us, which, unfortunately, we do not see. The fact is that many arthropods (insects, spiders, etc.) have one interesting feature: they glow in ultraviolet light.
Fireflies and other animals endowed with the ability of bioluminescence glow due to chemical reaction flowing in special organs of luminescence. Many people have seen this phenomenon. But scorpions, some spiders and a number of related organisms are able to produce a blue-green glow using the phenomenon of fluorescence.
Crab spider fluorescence The molecules of the exoskeleton (outer shell) of these animals absorb ultraviolet light (320-400 nm) invisible to our eyes, after which they re-emit ultraviolet into the bluish light visible to us.
It turns out that many arthropods glow under ultraviolet light. Photographer Nicky Bey (his photographs are used in the pro article along with mine) took a series of wonderful pictures of arthropod bioluminescence, with which I illustrated this text.
Why do arthropods glow in ultraviolet light?
In short, for many of the fluorescent animals, we don't know why. There is a lot of literature about the illumination of various arthropods, the main idea of which can be reduced to: “Wow! It's glowing!!!"
Kivsyaki also fluoresce in UV light True, for scorpions, the mechanism of this glow has been studied in more detail.
In scorpions, the so-called cuticular fluorescence is observed. It involves two compounds found in the epicuticle of the scorpion: beta-carboline and 4-methyl, 7-hydroxycoumarin. Coumarin, by the way, is used in perfumes or as a cinnamon flavor.
The fluorescence of scorpions is a very beautiful phenomenon. There are a couple of hypotheses regarding the purpose of scorpion fluorescence. Most insects can see ultraviolet light, so their world looks very different from ours.
Spider Heteropoda sp. human and insect eyes According to some experiments, scorpions can use the ability to absorb ultraviolet light to find shelter. During the experiment, the scorpions were put on tiny glasses, because of which the animals could not see with their eyes. But as soon as the UV light was turned on, the animals quickly found suitable shelters. Apparently, orientation occurred due to signals received from surface covers that absorbed ultraviolet (published in the journal Animal Behavior).
Maybe ultraviolet helps scorpions navigate According to another version, the glow of scorpions in the ultraviolet is a relic of the early Devonian period, when giant scorpions and centipedes inhabited the earth. The substances accumulated in the integument, capable of absorbing ultraviolet and emitting blue light, could protect ancient arthropods from sunburn. At least in young plant seedlings, it is coumarin that acts as a sunscreen.
Looking for traces of blood on various surfaces, as well as tools for committing a crime - this is one of the main tasks faced by employees of forensic centers and departments. At the same time, traces of blood can not always be identified visually. They can be washed out or have microscopic dimensions, which requires the use of specific methods for their search, in particular ultraviolet light.
The second sphere of application of ultraviolet lamps is the search for wounded animals on a bloody trail by hunters. Because on vegetation or ground at night, it is very difficult to replace.
How blood glows in ultraviolet light
When answering the question of whether blood glows in ultraviolet light, it should immediately be noted that this biological fluid does not fluoresce under the influence of UV rays. The blood completely absorbs the entire spectrum of ultraviolet radiation, acquiring an absolutely black color. It is for this reason that in various specialized forums one can meet negative feedback about lanterns (people expect it to start glowing) designed to search for blood. BUT the black color of blood is also the result. Because all other surfaces (grass, vegetation, earth, leaves) reflect ultraviolet light. Those. BLACK traces of blood will be clearly visible on the gray-blue-white surface of the forest. Therefore, you can answer YES, a UV flashlight can help find a wounded animal. But not in the way that many expect after watching movies. By the way, we will explain this below.
But how and why, in this case, is ultraviolet used to identify blood in criminology around the world?
In fact, the identification of blood is carried out using a special method, the essence of which is the processing of the alleged places of the presence of its traces. special composition- luminol. This organic compound is able to react with hemoglobin, which leads to blue fluorescence. That is why blood treated with such a composition glows in ultraviolet light. It is worth noting that this method provides the ability to detect even the smallest traces of blood washed with cleaning agents, since it is almost impossible to completely erase them.
Another feature of the search for blood with ultraviolet light is the short-term irradiation of its traces. The fact is that UV irradiation destroys DNA in the blood, which makes it impossible to further study it. That is why, when a positive reaction is obtained, exposure to UV light on the blood is suspended, and its samples are taken for further laboratory research. 
The catalog of our online store contains a wide selection of professional forensic and hunting UV flashlights for detecting blood traces. Each proposed model is developed on the basis of original high-quality components and meets all modern standards. Wholesale deliveries of flashlights to forensic centers and specialized laboratories are possible.
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UV lamp in the room
A few years ago, when I turned on the black light lamp for the first time in a dark laboratory, I had a feeling of unreality and even fantasy of the surroundings. Most of the things remained dark - they only slightly reflected the faint violet light of the lamp.
But some objects, inconspicuous with daylight, flashed brightly different colors. Most of it was blue. White wires and a colorless PVC tube, PET bottles and a plastic bucket shone blue. The paper became bright white with a bluish tint, the orange plastic became even brighter. Glowing colored stickers that were used as labels. A white robe, a shirt and some parts of a sweater shone.
Recently I tried to conduct experiments with a UV lamp at home (for lack of a laboratory). Impressions were quite different. If the walls in the laboratory were covered tiles and whitewashed, then the walls and ceiling of the houses were covered with wallpaper.
Part of the wallpaper was paper - the paper glowed in the UV, but there were no stains of glue, paint and other contaminants. As a result, the room looked unaesthetic: pollution hardly noticeable in daylight and electric light came to the fore - dark spots on a glowing background. Dark brown furniture in ultraviolet light seemed light brown, ugly.
The oil paint in the bathroom looked frankly scary, but in the bath itself I noticed bright blue spots - they glowed almost like a phosphor. It turned out that these are frozen pieces water-based paint from which I washed the bucket. The paint looked white, but a bright glow in the UV indicated that the paint was actually yellow, White color it gives a horse dose of optical brighteners.
An unpleasant surprise was that the cat marks in ultraviolet rays glowed green: it became clear that many of the surrounding objects would have to be thoroughly washed.
There was no desire to photograph the environment, so I started experimenting. Most of the experiments were carried out in dark room, some - by electric light.
In past experiments, a porcelain mortar that I photographed under UV light in the lab appeared to be dark purple (i.e. it simply reflected the lamp's dim purple light).
It turned out that white porcelain plates behave similarly, but there was also a significant difference. Visually, the plates look almost clean, but as soon as you turn on the black light lamp, the remains of dirt and debris become visible on the plate. detergent: porcelain did not glow, but dirt and / or detergent glowed green.
The inner side of the hand looked bright in ultraviolet rays, but the outer side was dark (like a Negro's) - only the nails glowed. In the photographs, the difference is not very clearly visible, because. when outside brush exposure was significantly longer.
The monitor screen (with a ray tube) glowed green in ultraviolet rays, and not very intensely. This is not surprising, since the phosphors applied to the screen of a kinescope are designed to glow under the action of an electron beam, and not soft ultraviolet rays.
A toy mouse made of fabric looked much prettier in ultraviolet light - some areas glowed brightly. The glow was noticeable even with electric light.
The colorless PET bottle glowed blue in the ultraviolet - so bright that it was clearly visible even when the electric light was on.
But the colorless PVC tube shone most brightly - it literally burned blue, like a fluorescent lamp. There is no doubt about the presence of optical brighteners.