Atnagulova E.R. 1
Magafurova F.F. 1
1 Municipal Autonomous educational institution"Average secondary school No. 154 of the city of Chelyabinsk"
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Introduction
Purpose of the work
Investigate the reasons for changes in color of various plant organs
Tasks
1. Studying the literature on the determination of pigments in plants.
2. Conduct chemical experiments to isolate pigments: chlorophyll, xanthophyll from pelargonium leaves, anthocyanins from beet roots.
3. Determine the dependence of changes in color of various plant organs on conditions environment.
3. Speak at a school scientific and practical conference.
Hypothesis
Changes in color of various plant organs depend on conditions external environment.
Object of study
Various parts of plants: pelargonium leaves, beet roots, violet flowers.
Subject of research
Plant pigments and changes in their color depending on external conditions.
Research methods
Descriptive, comparative, experimental, modeling, visual diagnostics.
Novelty of the work
A digital microscope was used to study conducting tubules in plant leaves.
Practical significance
Without huge economic costs, it is possible to find new mineral deposits necessary for the development and economic prosperity of Russia
The influence of the environment on changes in the color of various plant organs.
One of the main signs of autumn is the change in color of plant leaves. U different plants autumn colors are different, for example, the leaves of linden are yellow-green, poplars and birches are yellow. Oak leaves turn red. This variety of shades is due to the different combinations in autumn leaves three groups of pigments: yellow-orange carotenoids, green chlorophyll, red and blue anthocyanins.
Leaf color change always starts with the cessation of chlorophyll synthesis due to the drop in temperature. Chlorophyll is a pigment that is formed in green leaves under the influence of solar energy. In autumn, the ambient temperature drops, the sun does not shine so brightly, so the chlorophyll present in the chloroplasts begins to gradually collapse: in some species - completely (oak leaves), in others - partially (plum). in autumn there is a decline in vital activity due to preparation for the winter dormant period.
The chloroplasts of green leaves always contain green chlorophyll and yellow-orange carotenoids (xanthophyll). There are also anthocyanins in cells, but unlike chlorophyll, they are not associated inside the cell with plastid formations, butmost often dissolved in cell sap, sometimes found in the form of crystals.
Relevance of the problem
However, a change in the color of leaves, flowers, fruits is not always only the result of the cessation of chlorophyll synthesis and the attenuation of plant life processes. There are many environmental factors that affect the color change of various plant organs. Most often, when there is an excess of one or another chemical element or its deficiency, changes occur in various plant organs. For chemical scientists and agronomists, plants can serve as indicators of the content of nutrients in the soil, as well as the possible presence of ore deposits. In our time, when mineral resources on the planet are depleted, this problem comes to the fore .
We conducted a series of experiments on isolating pigments from plant leaves, and also investigated the influence of environmental factors on changes in the color of various plant organs.
Before conducting the experiments, we listened to the rules safety precautions when working in a chemical laboratory and strictly observed them.
Experiment No. 1. Anthocyanin release.
Reagents: 10% hydrochloric acid solution (HCl), 10% alkali solution (NaOH), distilled water, alcohol lamp, holder, matches, funnel, filter paper. When working with an alcohol lamp, first warm up the entire test tube, then set the flame in one place. When working with acid and alkali, wear rubber gloves.
A few pieces of chopped beets were boiled in a small amount of water. The water turned a dirty red color from anthocyanins. After filtering, we poured the solution into two test tubes, added a few drops of hydrochloric acid to one, and a few drops of alkali to the other. In the first test tube, the solution immediately became bright red, and in the other it turned yellow-green (see Appendix 1).
This experience proves that anthocyanin, depending on the environment in which it is found, can quickly change its hue. For example, in buds of lungwort cell sap has an acidic reaction, so the corolla is pinkish in color, and already fading lungwort flowers - blue, since the environment of cell sap is alkaline. Changes in flower color are a signal to pollinators about which flowers have recently opened and are more likely to contain food. Second example: potato tubers grown on peat soils have a bluish tint, but when potassium sulfate fertilizer is added to the soil, they become pink. Thus, environmental conditions directly affect the color change of anthocyanin in plants.
It should be noted that fruits and vegetables with blue, purple or red skin or flesh are an extremely healthy source of food for humans. Their use reduces the risk of cancer. Blackberries, blueberries, cherries, cranberries, eggplant, raspberries, red cabbage- products containing record amount of anthocyanins.We recommend them for use.
Experiment No. 2. Decolorization of anthocyanins with sulfur dioxide.
Reagents: sulfur (powder). Equipment: glass bell, iron spoon, matches. We carried out the experiment under a hood, since sulfur dioxide ( SO 2 )irritates the upper respiratory tract of humans. They also put on a cotton-gauze bandage.
A red pelargonium flower was placed under a glass bell, which was placed in a fume hood. They set fire to sulfur in an iron spoon and brought it under a glass bell, closing it tightly. We observed the filling of the entire space of the bell with sulfur dioxide, and after 5-7 minutes, a gradual discoloration of the petals of the pelargonium corolla. Sulfur dioxide affects anthocyanin amazing action: red flowers began to turn into white! (see Appendix 2).
Experiment No. 3. Isolation of chlorophyll and xanthophyll.
Reagents: 95% ethyl alcohol, gasoline, chalk. Equipment: porcelain mortar, test tube, funnel, filter paper.
Add 10 ml to crushed pelargonium leaves ethyl alcohol, on the tip of a knife, chalk to neutralize the acids of the cell sap, grind in a porcelain mortar until a homogeneous green mass. Add more ethyl alcohol and continue rubbing until the alcohol turns an intense green color. Filter the solution into a clean, dry test tube (see Appendix 3).
We separate pigments using the Kraus method. The method is based on the different solubility of chlorophyll and xanthophyll in alcohol and gasoline. Chlorophyll is more soluble in gasoline than in alcohol.
Pour 2-3 ml of the extract into the test tube, the same amount of gasoline and 1-2 drops of water. Close the test tube with your thumb and shake vigorously for 2-3 minutes. Let's settle. We observe: the liquid in the test tube is divided into 2 layers: petrol(bright green) at the top , alcohol(yellow) below. The xanthophyll pigment gives the alcohol solution its yellow color. The gasoline layer contains the pigment chlorophyll, which has a bright green color (see Appendix 3).
We believe that pigments give plants their vibrant colors. coloring to attract pollinating insects. Besides , the presence of pigments in plants is of great importance, both for the plants themselves and for humans. With the participation of the green pigment chlorophyll in the leaves of green plants, most unique And the only one in our solar system (and perhaps in the Universe!) process - photosynthesis. From carbon dioxide and water during action sun rays and the presence of chlorophyll in the leaves of plants, organic matter is formed - glucose and oxygen. Thanks to this process, life exists on planet Earth.
Experiment No. 4. The influence of metal ions on the color of Uzambara violet flowers.
We watered the Uzambara violet with blue petals with a solution of potassium permanganate (KMnO 4) for a month (once a week). To prepare a solution of potassium permanganate, several crystals of KMnO 4 were taken and dissolved in water. The solution turned bright pink. The color of the corolla petals began to change from pink. When watering an Uzambara violet with petals pink color solution of potassium alum (KAl(SO 4)2 .12H 2 O), the color of the corolla began to change to blue (see Appendix 4).
Thus , As a result of watering, colored solutions enter the plants from the soil and accumulate in the cells. We looked at the conducting tubules into a digital microscope and this is what they saw (Appendix 4).
Experiment.
My mother and I conducted the following experiment in the garden: we buried copper wires under a white rose bush, having first cut them finely. My dad gave us copper wires from an old TV. On next year in some rose buds we noticed bluish tint. What happened? We know that copper ions Cu 2+ in solution are blue, so when they accumulated in the plant, a color change occurred.
It is on the ability of plants to change their appearance depending on the chemical composition of the soil and air that the biogeochemical method of searching for mineral deposits.
The theoretical basis of this method is the teaching of academicians V. I. Vernadsky and A. P. Vinogradov about scattering halos chemical elements. According to this doctrine, at a deposit of a mineral there is a zone of increased concentration of an element included in its composition, or a dispersion halo.
Many plants adhere to soils with the same chemical composition and are “companions” of ores. In America there is lead grass growing over the deposit lead ore (Pb). In Belgium near the exits zinc ore (Zn) galmaine violet always grows, and on the dumps tin deposits(Sn) The weekday grows.
In our small homeland, the Urals, a small orchid grows - lady's slipper. This plant is listed in the Red Book of Russia as a rare species. The lady's slipper grows on the soils, rich in calcium (Ca). Having unexpectedly settled on the islands of Lake Onega, Lady’s slipper suggested to scientists a deposit of a valuable mineral. Plants are assistants to geologists; they often indicate underground deposits of minerals at depths of up to 20-25 meters.
Conclusion
We have experimentally established that plant cells contain the green pigment chlorophyll, yellow-orange xanthophyll, red and blue anthocyanins.
Our hypothesis was confirmed: environmental factors influence the color of various plant organs.
Knowing the dependence of changes in plant color on environmental conditions, it is possible to determine mineral deposits, as well as chemical composition soil, depth groundwater, nutrient content in the soil.
References
Artamonov V.I. Green oracles - M.: Mysl, 1989.
Baturitskaya N.V. Fenchuk T.D. Chemical experiments with plants: Book. for students. - M., 1991.
http://www.lepestok.kharkov.ua/bio/s20061201.htm
http://himik.my1.ru/publ/antociany_krasjashhie_veshhestva_rastenij/1-1-0-16.
Appendix 1
Anthocyanin changes color in acidic and alkaline environments
Appendix 2
Pelargonium petals become discolored in an atmosphere of sulfur dioxide
Appendix 3
Chlorophyll dissolves better in gasoline (top layer), and xanthophyll is found in the bottom layer of alcohol.
Appendix 4
Here's what we saw through a digital microscope:
The conducting tubules are pink in color because a colored solution of potassium permanganate (KMnO) comes from the soil 4 ).
Application
Appendix D
The chlorophyll pigment dissolves better in gasoline (top layer). Bright green color.
The bottom layer contains xanthophyll pigment dissolved in alcohol. Yellow-green coloration.
Anthocyanin changed color in an acidic environment.
In an alkaline environment, anthocyanin turns yellow.
Brian Thomas, MSc*
Scientists at the University of California, Santa Barbara, examined the genetics behind color variation in flower species, using the example of Aquilegia, a wildflower native to North America. The ability of aquilegia to change color from generation to generation is called an example of “adaptive radiation,” meaning rapid changes in any characteristic of a plant or animal species.
Adaptive radiation is a rapid phenomenon because the change can be fully observed in many populations of wild species. Because the macroevolutionary hypothesis of evolutionary development from simple to complex involves vast periods of time, changes resulting from adaptive radiation occur relatively quickly.
In the case of aquilegia flowers, the change in color results in a change in pollinators (certain moths and hummingbirds) that favor certain flowers. A news release from the University of California, Santa Barbara calls this process "evolution in action." But this color change has absolutely nothing to do with the proposed mechanism that controls large-scale evolution from amoeba to man. Are these closely related, interbreeding organisms evolving into something completely different? Do beneficial changes in DNA create entirely new traits? At least not with aquilegia.
The color of the aquilegia flower changes from blue to red and then from white to yellow, and the study authors “ the color change from red to yellow or red is believed to have occurred five times in North America" These studies indicate that the basis for color changes is destruction key genes through mutations in DNA. The loss of a key gene in the process of pigment formation leads to a “deviation” in the normal system. In cases where multiple genes are damaged by mutation, the flowers are white in color, since they completely lack pigment.
Researchers at the University of California, Santa Barbara have compiled a list of specialized proteins in the biochemical pathway that produces flower pigments. Many of these, as well as other additional proteins, must be present and fully functional for pigment formation to occur. This complex mechanism produces a highly specialized photoreactive macromolecule. Neither this adaptive radiation study nor any other study has yet shown how these kinds of molecular assembly lines can form naturally.
Researchers have discovered 34 different genes that are involved in the formation of pigments responsible for different shades of colors. Thus, in this system there are a number of places where changes in flower color through mutation can occur - and this does not happen by creating new genes, but by changing existing ones. Because this disruption of the genetic code produced an interesting genetic variation in flower color, new functional genes and new genetic information had to be produced for large-scale evolution to occur. What we actually observe in aquilegia is quite the opposite. Changes in some characteristics may occur, but the flowers that bear these characteristics were and still remain aquilegia.
Many scientists, such as those involved in this study, do not attach any importance to the destructive genetic changes that underlie flower color changes. Instead, they focus on how altered shades of color affect various types pollinators, suggesting that flowers somehow change to suit the birds and insects available. But although different pollinators can transmit information about different colors of certain shades, they do not form any new structures. In fact, they indicate the vitality invested in the creation by the Creator, who created flying organisms with special parts of the mouthparts, thanks to which they pollinate these plants, and also endowed their visual systems with sufficient plasticity so that they could recognize the mutated and degenerated shades of flowers.
Links and notes
Since color is one of the most striking and conspicuous features precious stones, there was no shortage of attempts to artificially change it.
Most often this is done by simple heating, or firing.
This is how Guettard, the Duke of Orleans’s physician, described the change in color of topaz by firing back in 1751: “Monsieur Dumel, a goldsmith who combines skill in his craft with commendable philosophical curiosity and a desire for research, especially everything with which he encounters in his work, he told me that Brazilian topazes lose their yellow color in the fire, acquiring instead a lighter or darker pink color, making them look like pale rubies. Some jewelers already knew about this change, which, as we thought, was known to us alone, but they diligently hushed it up and are still continuing to hush it up, since for them the profit that they can derive from it and indeed have often already often derived is much more important. than some petty philosophical curiosity.
They used their discovery to sometimes sell a fire-made ruby as a natural one, and traders probably never resorted to a more innocent deception. After all, the buyer actually gets a ruby for his money, and what importance is it that this ruby owes its perfection not to nature, since some art gives it a color as lasting as that of the best rubies, and all the more beautiful, the more inconspicuous and darker the topaz was? »
In conclusion, Guettard reports that this discovery was accidentally made by a stone cutter from Lisbon, dropping a stone into hot ash.
In the middle of the 18th century. by firing they were able to discolor brown, smoky, quartz, and a little later they learned to transform them in this way into lemon-yellow citrines. Carnelian roasting also dates back to the 19th century. used in India, near Baroda, pcs. Gujarat. Firing agates to a red color was first discovered in Idar (Germany) in 1813. There they noticed that yellowish and gray agates from one particular quarry (Ilgesheim, Glaserberg), which had lain for a long time on the surface of the earth, acquired a reddish tint, which the agates received directly from the quarry, not observed. This difference in color was initially attributed to the influence of sunlight and they began to expose agate products to the sun, but to no avail. Findings of red agates on fire pits then gave reason to suspect that heat could be the cause of the color change. However, the first attempts at firing did not produce successful results. Although the stones turned red, they cracked in the fire, falling apart. Only after they figured out to pre-fire the agates with long-term (several weeks) drying, was it finally possible to achieve the desired result. In a similar way, the color change of amethyst in fire was discovered: Brazilian gauchos (cattle herders) in the state of Rio Grande do Sul once placed several large pieces of amethyst close to the fire on which they were spit-roasting meat. Allegedly, the next morning, when they cooled down, these ores turned yellow. Colorless and green stones can also be obtained from amethyst by firing. When a large aquamarine weighing 110 kg was obtained in Idar in 1911, a successful attempt was made to change the color of its outer part from green to blue by heating. After this, it became common to change the color of greenish beryls by calcination. In the 1920s, when bluish tourmalines from Namibia came onto the market, they were given green tones by heating. Blue zoisites also owe their beautiful color to calcination.
All these color changes are irreversible, so there is no need to officially report them when selling stones. Only in some zircons the color change is reversible: after some time they return to their original color.
The second way to change the color of gemstones is irradiation. For example, colorless diamonds are given a green color in this way. We are talking about radioactive exposure, and the effect of a-, P- and y-radiation is not the same (P- and y-rays are especially effective). For amethysts that have faded in the light, radiation returns them to their original color; kunzite under its influence becomes green, like giddenite, etc. (although the color change is reversible).
Color changes also occur under the influence of ultraviolet and x-ray irradiation, but they are almost never used to change the color of precious stones. Sometimes the natural color of stones (for example, some zircons) is due to radioactive radiation. Smoky quartz owes its color to cosmic radiation, but it is also possible through radioactive irradiation to color rock crystal brown, that is, turn it into smoky quartz.
While changing the color of minerals by heat or irradiation does not introduce any foreign substances, coloring gemstones uses a dye. In this case, therefore, a change in the composition of the mineral occurs.
Already the Romans knew how to sell individual precious stones in other colors or improve their own color. For example, Pliny mentions writings that provide recipes for dyeing rock crystal and other transparent precious stones in the colors of emerald (emerald) or turning sarder into sardonyx. Pliny further reports that in Ethiopia, duller carbuncles were etched with acetic acid for 14 days, after which they acquired shine and retained it for the same number of months. In the 75th chapter of the 37th volume of his Natural History, the Roman writer mentions that some agate gems are most likely “made” rather than natural (that is, that their color is artificially changed). In addition, he tells how agate nodules, agate tonsils, found in Arabia were boiled in honey for seven days and seven nights and then processed by artists in such a way that veins, stripes and spots were revealed in the stone; this made them especially suitable for making jewelry.
Lessing already believed that Pliny could not have meant only cleaning the surface of the agates. The Decoctus melli Corsici (Corsican honey decoction) he mentions must have penetrated deeper into the gems and acted on the entire mass of the stone.
In the 18th century in Idar they also learned to identify multi-colored patterns on the surface of agates; this was done using solutions of metal salts. However, it remained unknown that some agate waters could be thoroughly saturated with dyes.
Gem polishers in ancient Rome were best able to color onyx-like agates black. Pliny's instruction about boiling agates in a honey solution was only part of the secret. Next, water was removed from the honey carbohydrates using hygroscopic sulfuric acid, after which the remaining black carbon was used.
In 1819, the art of painting agates black was mastered in Idar, which became the main reason for the flourishing of the agate industry there. The movement of the center of stone-cutting art from Italy to Paris was also, obviously, directly related to this discovery.
In 1822, they mastered the method of dyeing chalcedony light yellow (using nitric acid). By this time, apparently, they learned how to tint chrysoprase, enhancing its green color.
Since 1845, a method of coloring agates in blue by etching them with blood salt; in 1850, iron compounds were first used to give agates a red color. Since 1860 to impart green color to agates different shades chromic acid is used, and in 1822 a method was developed for coloring agates in brown and brown tones.
Already in 1824, a warning against painted stones was published: “The stone grinders in Oberstein and Idar-on-Nae have long practiced the art of so enhancing the color of domestic carnelians by boiling them in sulfuric acid that they became indistinguishable from the most beautiful Arab and Surinamese . Now they also know how to artificially transform almost transparent agate (chalcedony) into a beautiful milky-white stone. We have seen other chalcedony, painted in the same way in a magnificent lemon-yellow color, and they learned to impart the purest black color to the originally light brown stripes in the so-called onyx. Anyone who is not warned about this in advance cannot even think of considering such tones as artificial. Although stone polishers make no secret of the fact that they thus give different colors to stones, stones thus colored can easily, passing through other hands, mislead collectors.”
Dreher described in detail a variety of dyeing techniques that were kept by individual craftsmen as their highly private secrets.
For auction sale, 4 samples are made from each large piece of agate, which are given different colors so that interested buyers can figure out which color is best suited for a given piece. The main colors are red, black, blue and green.
Coloring was not limited to agates alone; later they began to artificially change the colors of other minerals. Various dyes were used to tint turquoise, but some of its own blue color was enhanced simply by waxing alone. Sometimes low-grade pieces of lapis lazuli were painted.
At one time, blue color was given to a certain type of jasper (from Nunkirchen in the Saarland region), throwing it on the market as “German lapis,” that is, simulating lapis lazuli.
The same changes in colors as artificial ones can occur in nature, however, in such cases, as a rule, they do not have an ennobling effect, but, on the contrary, quite significantly reduce the value of the stones. In this case, most often you have to deal with the phenomena of discoloration and fading. In mineralogical museums, specimens of minerals prone to fading are covered with dark cloth or boxes. Fade phenomena have been observed in amethysts from Switzerland and. in kunzites from Madagascar; Russian topazes from Transbaikalia lost their dark wine-yellow color and became bluish-white.
According to trade nomenclature regulations, the following artificially colored stones, that is, stones whose color has been artificially changed by physical, chemical or physicochemical action, must be specified:
stones that have undergone a color change by particle bombardment or irradiation (for example, yellow sapphire, kunzite or diamond); stones that have experienced a color change due to exposure to chemicals (black-dyed opal, artificially colored jade); they should be called so that the artificial change in their color is unambiguously clear from the name, for example, they should be written: artificially colored, covered with patina, ennobled, bombarded; blue-dyed lapis lazuli-like jasper, dyed jade, fired blue zircons.
Precious and ornamental stones that have acquired an irreversible and permanent color by firing or etching, for example, beryl, quartz, spodumene, topaz, tourmaline, zoisite, agate, are excluded from the regulations.
Aldridge writes: “... Octopuses surprisingly quickly and harmoniously color themselves to match the color of their surroundings, and when you shoot one of them and kill or stun it, it will not immediately lose the ability to change color. I observed this myself once, putting a caught octopus on a newspaper sheet for cutting. The octopus instantly changed color, becoming striped, with white and black stripes!” After all, he lay on a printed page and copied its text, imprinting on his skin the alternation of black lines and light spaces. Apparently, this octopus was not completely dead, its eyes still perceived shades of fading colors sunny world, which he left forever.
Even among higher vertebrates, few have the invaluable gift of changing skin color at whim or necessity, repainting themselves, copying the shades of external decoration.
Molluscs, arthropods and vertebrates are the three highest branches of the evolutionary development of the animal world, and only among them do we find skillful “chameleons” capable of changing color according to circumstances. All cephalopods, some crayfish, fish, amphibians, reptiles and insects have elastic, rubber-like cells hidden under their skin. They are filled with paint, like watercolor tubes. The scientific name for these wonderful cells is chromatophores. (Mammals and birds, also higher animals, do not have chromatophores in their skin, since, hidden under fur and feathers, they would be useless).
Each chromatophore is a microscopic ball (when at rest) or a pinpoint disk (when stretched), surrounded at the edges, like sun rays, by many subtle muscles - dilators, that is, dilators. Few chromatophores have only four dilators; usually there are more - about twenty-four. Dilators, contracting, stretch the chromatophore, and then the paint contained in it occupies an area tens of times larger than before. The diameter of the chromatophore increases sixty times: from the size of a needle point to the size of a pinhead. In other words, the difference between a contracted and an expanded colored cell is as great as between a two-kopeck coin and a car wheel.
When the dilator muscles relax, the elastic shell of the chromatophore takes its previous shape.
The dilators are perhaps the most tireless workers of all the working muscles in the animal kingdom. They don't know fatigue. Experimenters Hill and Solandg found that the force of their contraction does not decrease at all even after half an hour of voltage caused by exposure to electric current.
All other tireless muscles of animals (both the heart and wing muscles) work in a pulsating rhythm, when a period of contraction is followed by a pause of rest. Dilators remain in tension for hours without a break, maintaining the desired color on the skin.
The chromatophore stretches and contracts with exceptional speed. It changes its size in 2/3 of a second, and according to other sources, even faster - in 1/2 of a second.
Each dilator is connected by nerves to brain cells.” In octopuses, the “control center”, in charge of the change of scenery, occupies two pairs of lobe-shaped lobes in the brain. The front pair controls the color of the head and tentacles, the back pair controls the color of the body. Each blade controls its own, that is, the right or left side. If you cut the nerves leading to the chromatophores right side, then on the right side of the mollusk one constant color will harden, while its left half will play with different colors.
What organs correct the functioning of the brain, causing it to change the color of the body exactly in accordance with the background of the surroundings?
Eyes. The visual impressions received by the animal travel through complex physiological channels to the nerve centers, which send appropriate signals to the chromatophores. They stretch some, shorten others, achieving a combination of colors that is most suitable for camouflage. An octopus blind in one eye loses the ability to easily change shades on the eyeless side of the body. The disappearance of color reactions in a blinded octopus is not complete, because the change in color also depends on the impressions received not only by the eyes, but also by the suction cups. If you deprive an octopus of its tentacles or cut off all its suckers, it turns pale and, no matter how it puffs itself up, it cannot turn red, green, or black. If at least one sucker survives on the tentacles, the skin of the octopus will retain all its previous shades.
Cephalopod chromatophores contain black, brown, red-brown, orange and yellow pigments. The largest are dark chromatophores; in the skin they lie closer to the surface. The smallest ones are yellow. Each mollusk is endowed with chromatophores of only three colors: brown, red and yellow, or black, orange and yellow. Their combination, of course, cannot give the full variety of shades for which cephalopods are famous. Metallic shine, violet, silver blue, green and bluish opal tones impart to their skin a special kind of cells - iridiocysts. They lie under a layer of chromatophores and hide many shiny plates behind a transparent shell. Iridiocysts are filled, like funhouses in parks, with rows of mirrors, a whole system of prisms and reflectors that reflect and refract light, decomposing it into the magnificent colors of the spectrum.
In their richness of colors and perfect camouflage, cephalopods far surpass the famous chameleon. He would simply have been put to shame, like the unfortunate Marsyas by the radiant Apollo, if he had decided to compete in the play of colors with an octopus or cuttlefish. An irritated octopus from ash-gray in a second can turn black and turn into gray again, demonstrating on its skin all the subtle transitions and nuances in this range of colors. The countless variety of shades in which the octopus's body is painted can only be compared with the changing color of the evening sky and sea.
Octopuses resort to this amazing play of colors at critical moments of life in order to stun and frighten the enemy.“If you,” Aldridge writes, “notice an octopus and start pushing it with a gun, it will try to scare you away by constantly changing color, and this is a wonderful sight. He will bend and twist, inflate his body so as to appear huge, he will extend, move and retract his tentacles, pretend that he is ready to attack you; he will begin to bulge and roll his eyes, apparently trying to convince you of the credibility of everyone scary stories stories told about him. And if this does not frighten you, then he will shower you with a stream of ink and disappear in confusion with such incredible speed that he will leave you perplexed: why didn’t he immediately start by fleeing?”
Changing skin color is a kind of mimic language of an octopus. With the play of colors he expresses his feelings - fear, irritation, intense attention, and love passion. With fireworks of color flashes, they threaten rivals and attract the female. Their kaleidoscope of feelings is made up of golden orange and brown red tones. When the squid is not overwhelmed by emotions, it is colorless and translucent, like frosted glass. Then the ink sac gapes like a black hole on the milky body of the animal ghost. The squid owes its name to this circumstance. The word "squid" comes from the Italian "calamaio", which means "ink vessel". When irritated, the squid turns crimson or olive-brown, and its “inkwell” disappears behind darkened covers.
1The color fastness of clothing materials is an important indicator of the preservation of the aesthetic properties of clothing. Existing methods for assessing the color fastness of clothing materials to various influences do not allow for a quantitative assessment and the degree of significance of color changes in materials from the point of view of human perception. The paper proposes a method for assessing the color change of clothing materials, based on the processing of scanned photographic images of samples before and after exposure. Based on the obtained Lab characteristics of the CIE Lab color space, the color difference index ΔE is calculated. The assessment of the color change of semi-finished sheepskin leather fabric showed that the proposed method makes it possible to quantitatively assess changes in color characteristics, is a sensitive and more accurate assessment, and makes it possible to evaluate color changes that are significant for human perception. It was revealed that various influences (dry cleaning, light weather, dry and wet friction) lead to various changes in color characteristics (lightness, saturation, hue), which is assessed by the magnitude and sign of these characteristics.
impact
sheepskin semi-finished product
lightness
saturation
color difference
sustainability
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6. GOST R ISO 105-J03-99. Textile materials. Determination of color fastness. Part J03. Method for calculating color differences. – Enter. 12/29/1999 // Publishing house of standards. – M., 2000. – P. 11.
7. Dolgova E.Yu., Koitova Zh.Yu., Borisova E.N. Development instrumental method assessment of color fastness of clothing materials // News of universities. Textile industry technology. - 2008. - No. 6C. - pp. 15-17.
8. Domasev M.V. Color, color management, color calculations and measurements / M.V. Domasev, S.P. Gnatyuk. - St. Petersburg: Peter, 2009. - P.224.
The color stability of clothing materials during use largely determines their quality, since the constancy of the original color characteristics ensures the preservation of the aesthetic characteristics of clothing, which is one of the main consumer preferences.
The color stability of clothing materials to various types of exposure is determined in accordance with standards. New methods have also been developed and new indicators have been proposed for assessing color characteristics. However, these methods do not allow us to assess how significant color changes under operational impacts are from the point of view of human perception, because There is no quantitative assessment of color changes corresponding to the peculiarities of color perception by the human eye.
To quantify color changes, it is proposed to use the method of calculating color differences. To obtain the color characteristics of the test samples, their scanned photographic image is used, followed by processing in the Adobe Photoshop graphic editor (Fig. 1), in which it is possible to obtain the Lab color characteristics.
Figure 1 - Adobe Photoshop window with photographs of samples before and after exposure
To assess color change, the characteristic ΔE is used - color difference - which is defined as the difference between two colors in one of the equal-contrast color spaces. This characteristic takes into account the difference between the L, a and b color coordinates of the CIE Lab color space and the difference between the H° chromaticity and C saturation coordinates of the CIE LCH color space. The Lab characteristic is hardware-independent and corresponds to the peculiarities of color perception by the human eye, giving a more accurate assessment of the color change of the material.
The color difference ΔE is calculated using formula (1):
∆E = [()2 + ()2 + ()2]1/2 , (1)
where ∆L, ∆C, ∆H - the difference between the sample before and after exposure in lightness, saturation and hue, respectively, calculated using formulas (2), (4.5) and (6.7);
KL, KC, KH - weighting coefficients, which are equal to one by default;
SL, SC, SH - lengths of the semi-axes of the ellipsoid, called weight functions, allowing you to adjust their corresponding components, following the location of the color sample in the Lab color space, determined by formulas (7.8), (9.10) and (11-13) respectively .
Detection of lightness changes (2)
∆L = L1 - L2, (2)
where L1 is the lightness of the color of the sample before testing;
L2 - lightness of the color of the sample after testing.
Determination of sample color saturation (3):
C = 1/2, (3)
where a is the ratio of red and green colors in a given color;
b is the ratio of blue and yellow.
Detecting changes in saturation (4)
∆C = C1 - C2, (4)
where C1 is the color saturation of the sample before testing;
C2 - color saturation of the sample after testing.
Definition of color tone (5):
H = arctan,(5)
Detection of color tone change (6)
∆H = 2sin, (6)
where H1 is the color tone of the sample before testing;
H2 - color tone of the sample after testing (5).
Determination of the average lightness value of samples before and after testing (7.8):
= (L1+ L2)/2 (7)
where K2 = 0.014 is the weighting coefficient.
Determination of the average saturation value of samples before and after testing (9.10):
C12 = (C1 + C2)/2 (9)
SC= 1 +K1C12, (10)
where K1 = 0.048 is the weighting coefficient.
Determination of the average color tone of samples before and after testing (11-13):
T= 1-0.17cos(H12 - 30°)+0.24cos(2H12)+0.32cos(2H12 + 6°)-0.2cos(4H12 - 64°)(12)
SH= 1 + K2C12T(13)
When calculating H12, it should be taken into account that if the chromaticities of the samples fall into different quadrants, then 360° must be subtracted from the chromaticity value that is the largest and then the average must be determined.
By the magnitude of the color difference, one can judge the degree of change in the color of materials after various influences. ΔE value< 2 соответствует минимально различимому на глаз порогу цветоразличия, величина в пределах ΔE = 2—6 приемлемо различимая разница в цвете. Величина ΔE >6 will correspond to a noticeable difference between the two colors. By the sign of changes in lightness, saturation and color tone, one can judge the degree of change in these characteristics of the material.
Currently produced semi-finished sheepskin products are distinguished by a wide variety of colors, types of finishing of leather fabric and hair. During wear and care, products experience a complex set of various influences that lead to deterioration. appearance products. Therefore, to test the proposed method, an assessment was made of the color change of semi-finished sheepskin with different color characteristics of leather fabric and under different types of exposure (dry cleaning, light weather, dry and wet friction) (Table 1).
Table 1 - Assessment of color fastness of semi-finished sheepskin leather fabric under various types of influences
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Type of impact |
Sample of semi-finished product |
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Before exposure |
After exposure |
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Dry cleaning |
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Sheepskin fur, black leather fabric |
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Light weather |
Sheepskin coat, black leather fabric |
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Sheepskin fur with polymer film coating, light brown leather fabric |
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Fur velor, dark green leather fabric |
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Dry friction |
Sheepskin coat, brown leather fabric |
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Fur velor, brown leather fabric |
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Sheepskin fur, dark gray leather fabric |
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Wet friction |
Fur velor, brown leather fabric |
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Fur velor, brown leather fabric |
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Fur velor, light gray leather fabric |
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Analysis of the data obtained shows that the greatest color changes occur during dry cleaning. The color difference values reach 12.7, which is a significant indicator of color change. At the same time, the color of the material becomes less saturated and lighter. During wet friction, the material darkens, as evidenced by positive values indicator ∆L - lightness, while with other types of exposure this indicator has negative values, which indicates that the material with this type of exposure becomes lighter. External influences lead to changes in the indicator ∆H - light tone. When this value is exceeded by 4 units, the tone of the material changes significantly.
Thus, the proposed method for assessing changes in color characteristics makes it possible to obtain quantitative indicators of color changes, is sensitive and makes it possible to evaluate color changes that are significant for human perception, and to study the kinetics of changes under the influence of a certain operating factor. It can be used to assess color stability at the dyeing stage semi-finished sheepskin product, at the preparatory stage when selecting skins for the product in order to exclude different shades, during dry cleaning to assess its degree of influence on color changes.
Reviewers:
Sokova G.G., Doctor of Technical Sciences, Professor, Acting Head of the Department of Technology and Design of Fabrics and Knitwear, Kostroma State Technological University, Kostroma.
Galanin S.I., Doctor of Technical Sciences, Professor, Head of the Department of Technology, Artistic Processing of Materials, Artistic Design, Arts and Technical Services, Kostroma State Technological University, Kostroma.
Bibliographic link
Borisova E.N., Koitova Zh.Yu. USING THE METHOD OF CALCULATING COLOR DIFFERENCES TO EVALUATE CHANGES IN COLOR OF SEMI-FINISHED SHEEPSKIN // Contemporary issues science and education. – 2013. – No. 5.;URL: http://science-education.ru/ru/article/view?id=10468 (access date: 06/15/2019). We bring to your attention magazines published by the publishing house "Academy of Natural Sciences"