It's no secret to anyone that all living beings on our planet are composed of their cells, these countless "" organic matter. Cells, in turn, are surrounded by a special protective shell - a membrane that plays a very important role in the life of the cell, and the functions of the cell membrane are not limited to protecting the cell, but represent the most complex mechanism involved in cell reproduction, nutrition, and regeneration.

What is a cell membrane

The word “membrane” itself is translated from Latin as “film”, although the membrane is not just a kind of film in which the cell is wrapped, but a combination of two films interconnected and having different properties. In fact, the cell membrane is a three-layer lipoprotein (fat-protein) shell that separates each cell from neighboring cells and the environment, and carries out a controlled exchange between cells and the environment, this is the academic definition of what a cell membrane is.

The value of the membrane is simply enormous, because it not only separates one cell from another, but also ensures the interaction of the cell, both with other cells and with the environment.

History of cell membrane research

An important contribution to the study of the cell membrane was made by two German scientists Gorter and Grendel back in 1925. It was then that they managed to conduct a complex biological experiment on red blood cells - erythrocytes, during which scientists received the so-called "shadows", empty shells of erythrocytes, which were folded into one pile and measured the surface area, and also calculated the amount of lipids in them. Based on the amount of lipids obtained, the scientists came to the conclusion that they are just enough for the double layer of the cell membrane.

In 1935, another pair of cell membrane researchers, this time the Americans Daniel and Dawson, after a series of long experiments, determined the protein content in the cell membrane. Otherwise, it was impossible to explain why the membrane has such a high surface tension. Scientists cleverly presented a model of the cell membrane in the form of a sandwich, in which the role of bread is played by homogeneous lipid-protein layers, and between them instead of butter is emptiness.

In 1950, with the advent of the electronic theory of Daniel and Dawson, it was already possible to confirm practical observations - on micrographs of the cell membrane, layers of lipid and protein heads and also an empty space between them were clearly visible.

In 1960, the American biologist J. Robertson developed a theory about the three-layer structure of cell membranes, which for a long time was considered the only true one, but with the further development of science, doubts about its infallibility began to appear. So, for example, from the point of view of cells, it would be difficult and laborious to transport the necessary useful substances through the entire “sandwich”

And only in 1972, the American biologists S. Singer and G. Nicholson were able to explain the inconsistencies of Robertson's theory with the help of a new fluid-mosaic model of the cell membrane. In particular, they found that the cell membrane is not homogeneous in composition, moreover, it is asymmetric and filled with liquid. In addition, cells are in constant motion. And the notorious proteins that make up the cell membrane have different structures and functions.

Properties and functions of the cell membrane

Now let's look at what functions the cell membrane performs:

The barrier function of the cell membrane - the membrane, as a real border guard, stands guard over the boundaries of the cell, delaying, not letting through harmful or simply inappropriate molecules

The transport function of the cell membrane - the membrane is not only a border guard at the gates of the cell, but also a kind of customs checkpoint, through which the exchange of useful substances with other cells and the environment constantly passes.

Matrix function - it is the cell membrane that determines the location relative to each other, regulates the interaction between them.

Mechanical function - responsible for limiting one cell from another and in parallel for correctly connecting cells to each other, for forming them into a homogeneous tissue.

The protective function of the cell membrane is the basis for building a protective shield of the cell. In nature, this function can be exemplified by hard wood, a dense skin, a protective shell, all due to the protective function of the membrane.

The enzymatic function is another important function performed by some cell proteins. For example, due to this function, the synthesis of digestive enzymes occurs in the intestinal epithelium.

Also, in addition to all this, cell metabolism is carried out through the cell membrane, which can take place in three different reactions:

• Phagocytosis is a cellular exchange in which phagocytic cells embedded in the membrane capture and digest various nutrients.
• Pinocytosis - is the process of capture by the cell membrane, fluid molecules in contact with it. To do this, special tendrils are formed on the surface of the membrane, which seem to surround a drop of liquid, forming a bubble, which is subsequently “swallowed” by the membrane.
• Exocytosis - is the reverse process, when the cell releases secretory functional fluid through the membrane to the surface.

The structure of the cell membrane

There are three classes of lipids in the cell membrane:

• phospholipids (they are a combination of fats and),
• glycolipids (combination of fats and carbohydrates),
• cholesterol.

Phospholipids and glycolipids, in turn, consist of a hydrophilic head, into which two long hydrophobic tails extend. Cholesterol, on the other hand, occupies the space between these tails, preventing them from bending, all this in some cases makes the membrane of certain cells very rigid. In addition to all this, cholesterol molecules regulate the structure of the cell membrane.

But be that as it may, the most important part of the structure of the cell membrane is protein, or rather different proteins that play various important roles. Despite the diversity of proteins contained in the membrane, there is something that unites them - annular lipids are located around all membrane proteins. Annular lipids are special structured fats that serve as a kind of protective shell for proteins, without which they simply would not work.

The structure of the cell membrane has three layers: the basis of the cell membrane is a homogeneous liquid lipid layer. Proteins cover it on both sides like a mosaic. It is proteins, in addition to the functions described above, also play the role of peculiar channels through which substances pass through the membrane that are unable to penetrate the liquid layer of the membrane. These include, for example, potassium and sodium ions; for their penetration through the membrane, nature provides special ion channels of cell membranes. In other words, proteins provide the permeability of cell membranes.

If we look at the cell membrane through a microscope, we will see a layer of lipids formed by small spherical molecules on which proteins float like on the sea. Now you know what substances are part of the cell membrane.

Cell membrane, video

And finally, an educational video about the cell membrane.

This article is available in English - .

Membrane fabric is an innovative material with selective permeability. Possesses the increased protective properties. It is used for the production of children's, sportswear, equipment for fans of active winter recreation, representatives of extreme professions.

Why are membranes needed?

Membrane fabrics: samples

The word "membrane" is of ancient origin and means "membrane". In ancient times, it was used in the ordinary and biological sense. As science developed, the term acquired a physical, chemical, technical meaning. Now membrane technologies are used in the light industry for the production of clothing.

One of the main functions of clothing is protective. Previously, rubber shoes, polyethylene raincoats, capes from others were used to protect against rain. From rain, snow, wind, these materials protected well for some period of time. It is impossible to stay in waterproof products made according to old technologies for a long time.

The human body, on average, releases more than half a liter of moisture per day, which accumulates on clothes from the inside if there is no way out. With active movements, the amount of sweat released can reach one and a half liters.

The introduction of membranes into the composition of protective fabrics allows you to remove water vapor, while preventing moisture, wind, rain, snow from getting inside.

The structure and mechanism of action of membranes

The simplest example of a membrane product is a plastic bag (not to be confused with polyethylene). If, for example, a salted protein solution is poured into a plastic bag and suspended in a container of clean water, then after a while the salt will penetrate through the pores of the cellophane into the water. Cellophane selectively lets small molecules out, retains large ones inside, water molecules from the outside do not seep into the bag.

The principle of action of membrane tissue

The membrane layer in tissues works in a similar way. It lets small molecules out without letting anything in.

Membranes used in light industry are usually divided into porous (containing pores) and non-porous (supposedly not containing pores). The division is conditional, but widespread. It is advisable to use it.

• Membranes with pores are thin polymer layers with very small holes through which gaseous water (steam) molecules can seep from the inside, but drops do not fit there. Recall the course of the school: in a drop, water molecules “stick together” - they are in the form of associated groups. In the vapor state, water molecules are alone, the distance between them does not allow them to unite. The American company Gore-TeX makes membrane fabrics from Teflon, for 1 cm 2 of which there are about one and a half billion micro-holes - pores.
• Membranes without pores act differently. They also contain many microcells with a complex, sinuous shape, reminiscent of the structure of a sponge. The steam from the skin is absorbed into the cells, saturates the membrane, turns into condensed moisture and, due to the difference in partial pressure (this concept is also from school courses), is released to the outside. This principle of separation is possible because there are more vapors inside than outside. If, hypothetically, the wearer of the clothing enters a sauna or other room with very high humidity, the moisture will enter in the same way.

In some materials, different membranes are combined, a layer without pores is laid on the outside, and with pores on the inside. The fabric is effective but expensive.

Comparison of terms of use

• All membrane tissues carry vapors from an area of ​​high pressure to an area of ​​low pressure (according to gradient experts).
• At high humidity, membranes with pores are better able to remove vapors to the outside, especially if there is ventilation on clothing. Non-porous membranes are effective in relatively dry air environments. If humidity is high or ventilation is open, such a membrane will not work well.
• At low temperatures, a membrane with pores works better. At negative temperatures of the material, pore-free membranes simply freeze.
• A porous membrane may become clogged if not properly cared for or worn. Poreless membrane fabrics are durable and last a long time.

Main characteristics

Membrane fabrics are designed to protect against the weather and create a sense of comfort for wearers. Functions justify the importance of key indicators.

• Waterproof. At high pressures of the water column, any tissue will begin to leak. For successful operation, the values ​​of the maximum tolerable impacts are important. Clothing designed for harsh conditions must withstand pressures of 20,000 mm of water column and above. A value of 10000 mm is acceptable for normal rainy conditions.
• Vapor permeability characterizes the mass of steam in grams, which can be removed by 1 m 2 of material in a given unit of time (usually 24 hours). The most common minimum vapor permeability is 3000 g / m 2, the maximum - from 10,000 g / m 2. Sometimes this property is measured by the ability to resist steam transport (RET). If this indicator is equal to 0, the fabric completely passes all the steam, with a value of 30, the passage of steam is practically excluded.

The membrane does not perform insulating functions. It saves from rain, wind, snow, provides "breathing" to the body, helps to provide thermal comfort.

Fabric structure

Structurally, membrane fabrics differ in execution.

• In two-layer fabrics, the membrane is fixed on the inside of the fabric. Additionally, it is closed with a lining that protects against damage and clogging.
• In three-layer fabrics, the following are glued together: the outer layer, the membrane, the inner mesh. The need for a lining layer is eliminated. The material is very comfortable, it is more expensive.
• In some modifications, a special protective coating is sprayed on the inner surface of the two-layer fabric.
• There are types of membrane fabrics with a water-repellent layer (DWR) applied on top. The coating may wash off over time. It is easily restored by special means.

Leading manufacturers

Membrane fabric in clothes

The most authoritative, historically the first manufacturer of membrane fabrics is Gore-TeX. She made clothes for astronauts. Then several types of products were offered to skiers, climbers, mountain tourists.

Clothing with Triple-Point, Sympatex, ULTREX membranes is comparable in quality. The material is solid, available in several versions. The price is high, corresponds to the properties of the products.

Products with Ceplex, Fine-Tex membranes have an affordable price. It is designed for a maximum of 2 seasons of active wear, after which the material may begin to let water through a little.

When buying clothes made of membrane fabrics, pay attention to the information about gluing the seams. In some varieties, absolutely all seams are glued, in others - only the main ones. For wearing in the city, gluing the main seams is enough. For active sports, it may be better to choose products with all reinforced seams. The choice is up to the potential wearer.

Rules for the care of membrane tissues

The material is specific in composition and structure. Normal washing methods should not be applied to this group of products.

• You can wash the fabric with a membrane layer in the machine using a gentle mode and soft special products.
• You can't push in the car.
• You can't take it to the dry cleaners.
• Ironing is not necessary, it is not necessary to do this.
• Can be washed by hand if desired.
• You can leave the thing in an arbitrary straightened state so that water flows from it.
• The fabric is very slightly soiled. After wearing, drying, it can be lightly brushed with a regular brush.

Fabrics with membrane materials allow you to feel protected in any bad weather with the most active activities.

Membrane- this is perhaps the main material in tourism, which causes heated debate more than others. Most likely this happens because this word is used in many other areas: from astronautics to medicine, and there is a little confusion. But in our case, the membrane is a material that is designed to protect tourists and travelers from external weather conditions and at the same time remove fumes from the inside of the product to the outside, or simply “Breathe”. We will try to use the word “breathe” less often, because it is precisely because of its misinterpretation that the membrane has become overgrown with many misconceptions.

The easiest way to imagine what a membrane is is as follows: take the most ordinary piece of polyethylene and make a thin needle with a dozen holes in it - that's all! We have a simple membrane in our hands. Like any membrane, ours has two main characteristics: water resistance and vapor permeability, and it’s pretty easy to understand what’s what. Let's put a leaky polyethylene on a flask with water. By inverting the flask and observing whether water flows through, we will find out the water resistance of our membrane. And if we boil the water in the flask and observe how much steam comes out through the holes, we will measure the vapor permeability.

Such a simple example allows us to understand the following: Membrane is the same material as base tissues, only with a different structure and chemical composition. That is, it does not have any mechanical valves that open for sweat and close from the outside from the rain (many will find this ridiculous, but after working for many years in the store, I assure you, this is not the most exotic version yet). And the second, important thing: the real membrane, like our piece of polyethylene, does not have a side - it works in both directions in the same way! This means that a drop of sweat from the inside will also not pass through the jacket, just as a drop of rain will not pass from the outside. At the same time, water vapor from the surrounding atmosphere can pass through the membrane storm in the same way as evaporation from the body goes through it.

I think I've written enough to understand that the membrane is not a magical substance that magically protects you from bad weather and instantly removes excess moisture to the outside. And now, quite naturally, the question arises: “Does the membrane work at all, and do we need it?” The answer is unequivocal - it works, and yes, it is much more comfortable with it! You don't think that the millions of dollars spent on developing hundreds of types of membranes went into needles and polyethylene, do you? I am sure not, so we will continue to talk only about modern technologies.

Membrane characteristics

As I wrote above, membranes are characterized by two main indicators: water resistance and vapor permeability. Let's analyze them in more detail.

Water resistance is the height of the water column that the membrane can withstand without getting wet. It is measured in millimeters, or another unit of measurement is used - PSI (Pounds per Square Inch - pounds of weight per square inch). All materials with a PSI value over 25 are considered to be waterproof, and a value from 1 to 24 PSI indicates water resistance of materials. We already got acquainted with this characteristic in the first article on basic materials.

And most importantly for us: the higher this indicator, the better. Only if you are not engaged in extreme tourism, it is unlikely that you should overpay for a tent with a membrane fabric of 20,000 mm.

Vapor permeability. If the meaning of this characteristic is well understood, then you can get confused in numbers and measurements, and unscrupulous manufacturers are happy to use this, indicating a huge number, indicating sometimes sad test results.

The general essence of all tests is to measure the following indicator: the amount of water in grams that will evaporate from a square meter of fabric in 24 hours (g / m2 / 24h). The indicator is abbreviated as MVTR (moisture vapor transmission rate - moisture vapor transmission rate). But how this indicator is obtained is a topic for a separate article, which we will not delve into (for those who want to do this, I recommend an article published on the website of the clothing manufacturer - Sivera). In short, the whole set of tests, one way or another, is carried out in laboratories, under certain conditions that are very different from real operation. And the most unpleasant thing for the end user is that the result of one of the tests can be an impressive number that does not reflect the essence. This value will be written on the label, and you and I will only have to trust the manufacturer. However, it is worth saying that the test labeled MVTR B2 is considered the most universal method.

Summarizing the above, I would like to say that the vapor permeability indicators on product labels should not be taken too critically. It is better to learn more about the purpose of the purchased equipment and try to choose only products from well-established manufacturers. Beware of fakes, there are a lot of them, especially the most famous brands like The North Face or Marmot. The membrane is a technologically complex thing and it physically cannot be cheap, if it is not polyethylene with holes, of course.

Membrane layers

The membrane itself is a very fragile and thin sheet of material, which in the final product must necessarily be applied to another material. It happens that the membrane in liquid form is applied to the base, in which case they speak of a membrane coating. The way in which a sheet of the finished membrane is attached to the material gives a new name - laminate.

Allocate three main types membrane designs:

Double layer, in which the membrane is protected only from the outside - marked as 2L. This method is good for saving weight and high vapor permeability, however, the inside is still protected by a lining, most often from a mesh. It is also used in clothes with an inner insulating layer.

Two and a half layers– 2.5L. As in the first case, the material has two layers, but a protective layer of non-woven material is additionally applied to the inside. Products made from such membranes are very light and compact.

3 layer construction or 3L, which means that the membrane is protected with cloth on both sides. The main advantage of such a sandwich is the maximum wear resistance of the membrane.

Almost always, the top layer of any of the structures is covered with water-repellent coatings or DWR.

Types of membranes

Hydrophobic or porous membranes. If we take our piece of polyethylene again, then it just can be classified as a “pore membrane”. That is, the material has millions of microscopic pores through which vapor molecules pass, but water drops do not pass. Only a real hydrophobic membrane is made not like us, from polyethylene, but from Teflon or polyurethane. However, these very pores become clogged over time and the material significantly loses its breathable properties. In addition, most pore membranes are not very elastic, that is, it is problematic to find “stretch” suits from it.

Hydrophilic or non-porous membranes. This type of material no longer has open pores through which steam would pass; instead, the fabric absorbs moisture and transports it to the opposite side. And here it is worth remembering that the membrane as such does not have an inner and outer side - it is the same, and there are no arrows in it that indicate the direction in which moisture needs to move. The transport of water molecules occurs due to the so-called moisture gradient. That is, moisture from the body, falling on the inner layer of clothing, begins to be absorbed into the fabric, passes from layer to layer to the opposite side and, falling on the outer part of the product, evaporates. If the humidity outside is very high, then the efficiency of moisture removal of such a membrane is significantly reduced. The chemical composition is most often polyurethane or polyester.

Combined membranes. Probably, trying to get rid of the shortcomings of porous and non-porous membranes, the manufacturers came up with the idea of ​​combining them: that is, a continuous layer of polyurethane is applied to the layer of the hydrophobic membrane. This layer is much thinner than classic non-porous fabrics and is designed to protect the more fragile structure of the pore top layer.

Which membrane to choose?

As always, there is no single answer. Each type of membrane is suitable for certain conditions, so let's highlight the main pros and cons of the three types of membranes.

Pore

+

• high efficiency of steam removal in conditions of high humidity and at low temperatures.
• good breathability
• excellent water resistance performance

-

• low elasticity
• easy to get dirty
• requires special care

Non-porous

+

• excellent breathability
• unpretentiousness
• elasticity
• good water resistance performance

-

• do not perform well in high humidity and low temperatures.

Combined

They have the same advantages as the previous ones, but there are also disadvantages of the non-porous layer, although to a much lesser extent due to the thinner layer of polyurethane.

About firms

At first glance, it seems that the number of manufacturers is simply unrealistic, since the list of names is huge. But in reality, it turns out that not so many companies produce high-quality membranes. The fact is that many brands that make clothes order membranes that are essentially the same and come up with their own names for them. For example, the widely advertised Teaxapore membrane of the German company JackWolfskin is nothing more than the long-known Entrant fabric of the Japanese company Toray, they also work closely with the American company Marmot and produce the Marmot MemBrain membrane.

Speaking of membrane companies, it is impossible not to say about Gore-tex, but rather “W. L. Gore & Associates because Gor-tex is just one of the fabrics they make. Yes, and Gor-tex has a dozen more articles with different characteristics. By the way, Gore-tex was the first to use the combined membrane technology, thereby establishing itself as an industry leader for many years.

Another interesting membrane is eVent. Its peculiarity is that although it is a porous membrane, its fibers are covered with polyurethane; while at the same Gore-tex polyurethane is applied in a continuous layer on the main film. This greatly increases the breathability of the fabric. eVent is a rather expensive material and, moreover, there are difficulties with gluing seams on products made from this membrane, as a result, the price of the final product is quite high.

You can delve into the names and technologies used for a long time, but, as it seems to me, the real qualities of products made of membrane fabric can only be learned from personal experience. A lot of factors affect the behavior of the membrane in different conditions, and what is ideal for one person will not be at all like another. With experience, you yourself will understand what points to pay more attention to, and what you can close your eyes to. For the very first purchases, as always, I advise you to listen to the descriptions and advice of the clothing and equipment manufacturers themselves. Believe me, they do a very great job of designing and building models and all this for you and me. Of course, their goal is to make money, but self-respecting brands are primarily aimed at long-term friendship with us, so do not be afraid to trust those whose profession is to create comfortable conditions in the toughest and most unpredictable situations.

In custody

The membrane is a great thing with which your hobbies will become much more comfortable! Just do not forget that this is not a magical shell. In any case, a person sweats - this is a natural process - the membrane only helps to evaporate this moisture to the outside. And, at the same time, not every membrane windbreaker can withstand many hours under a torrential downpour. But it will be a much more comfortable watch than if you were climbing uphill in a rubber, absolutely waterproof raincoat. Many skeptics will dissuade you with shouts, there is nothing cooler than a tarpaulin, but I persuade you to try and not be skeptical, but try to understand your feelings and form your own opinion about the membrane.

I hope this article will be useful to you, but in the next one, we will talk about heaters. More travels and see you soon!

(from lat. membrana - skin, membrane) in acoustics, a flexible thin film, given external. forces into a state of tension and, as a result, elasticity. It is necessary to distinguish a plate from M., a cut depends on its material and thickness. Examples of M. - skin stretched on a drum, thin metallic. foil, which plays the role of a movable lining of a condenser microphone. Own M. are represented by systems of standing waves with one or another picture of nodal lines, to-rye separate parts of M., oscillating with opposite phases (Fig.); ext. the contour, along which the M. is clamped, is always a nodal line, if the fixation is such that there is no displacement perpendicular to the M. plane. systems of standing waves correspond to dec. oscillation frequencies, the totality of which determines the discr. own frequencies M. Forced oscillations M. under the action of concentrated or distributed periodic. ext. forces occur with a frequency of ext. impact; when it coincides with one of the properties. frequencies M. takes place.

The form of some properties. vibrations of the membrane: a - rectangular; b - round. The arrows indicate the nodal lines; i, k - numbers of harmonics.

Physical Encyclopedic Dictionary. - M.: Soviet Encyclopedia. Editor-in-Chief A. M. Prokhorov. 1983 .

(from lat. membrana - skin, membrane) - a flexible thin film, given externally. forces into a state of tension and, as a result, elasticity. M. refers to two-dimensional fluctuations. systems with distributed parameters. The elasticity of M. depends only on its material and tension, in contrast to plate, the elasticity of a cut is determined by its material and thickness. Distinguish, a feature of M. is the need to secure it on the outside. contour. Examples of M. are skin stretched over a drum, thin metallic. foil, which plays the role of a movable lining of a condenser microphone, etc.

Neglecting the dissipation of energy, oscillations of a homogeneous, uniformly stretched M. can be described by the equation

where - the displacement of the surface element M. from the equilibrium position in the direction of the normal to the plane of tension, - surface M., T- tension, - Laplace operator. Boundary conditions for M.on ext. contour; as the beginning conditions is given by the displacements and velocities of the points of the surface M. in the beginning. moment of time t= 0. Natural (free) oscillations of M. are represented by systems of standing waves. M.'s sections, oscillating with opposite phases, are separated by nodal lines. The totality of own vibration frequencies M. is a discrete spectrum. For a rectangle M. (Fig. 1) with sides a and 6 own. frequencies are expressed f-loy

The frequency w is fundamental (lowest); overtones, etc. are the harmonics of the main. frequencies. Case (square M.) called. degenerate, in square M. a simple harmonic is possible. in the form of traveling waves, while the nodal lines during the period consistently take dec. configuration.

Rice. 1. The shape of the first four natural oscillations of a rectangular membrane; arrows indicate nodal lines.

Rice. 2. The shape of a round membrane for some natural oscillations; arrows indicate nodal lines.

Own oscillation frequency of round M. (Fig. 2) radius but can be found from the equation

where J k - Bessel function of the 1st kind k th order, a k And l are the numbers of nodal diameters and nodal circles, respectively. In the case of a round M., none of the overtones is a harmonic of the main. frequency w 01 .

Forced vibrations M. occur with a frequency of ext. impact, when coinciding with a swarm with one of their own. frequency takes place resonance. M. is a sound emitter with an uneven distribution of vibrations. surface speed. Radiation M., excited on the main. frequency, has less directivity than at the same frequency of a piston diaphragm of the same configuration.

Lit.: Strett D JK. V. (Lord Rayleigh), Theory of sound, trans. from English, 2nd ed., vol. 1, M., 1955; Morse F., Fluctuations and, trans. from English, M.-L., 1949; Skuchik E., Fundamentals of acoustics, trans. from German, vol. 1, M., 1958. S. V. Egerev.

Physical encyclopedia. In 5 volumes. - M.: Soviet Encyclopedia. Editor-in-Chief A. M. Prokhorov. 1988 .

Synonyms:

See what "MEMBRANE" is in other dictionaries:

Membrane- a thin flexible plate, fixed along the perimeter, designed to separate two cavities with different pressures or separate a closed cavity from the total volume, as well as to convert pressure changes into linear movements and ... ... Dictionary-reference book of terms of normative and technical documentation

- (Membrane, diaphragm) thin, flexible, stretched plate. Round membranes, clamped around the circumference, are used in all sound transmitting and sound receiving devices (telephone, microphone, gramophone). Such a membrane easily responds to vibrations ... ... Marine Dictionary

Diaphragm, pendulum, resonator, damper; membrane, diffuser, pneumomembrane Dictionary of Russian synonyms. membrane noun, number of synonyms: 9 axolemma (1) … Synonym dictionary

membrane- Ndp. diaphragm A flexible, contoured partition separating two cavities with different pressures or separating a cavity from space and converting pressure changes into movement or vice versa [GOST 21905 76] membrane Thin flexible ... ... Technical Translator's Handbook

Membrane- * membrane * membrane is a thin boundary structure located on the surface of cells and intracellular particles, as well as tubules and vesicles in the cellular contents. Performs various biological functions provides cell permeability ... ... Genetics. encyclopedic Dictionary

- (from Latin membrana membrane) 1) in the theory of elasticity, an infinitely thin film fixed along the contour, the elastic modulus of which in the direction perpendicular to the surface is zero. 2) In technology, a thin film or plate (usually fixed along ... ... Big Encyclopedic Dictionary

MEMBRANE, in biology, the boundary layer inside or around a living CELL or TISSUE. Cell membranes include the plasma membrane surrounding the cell, the system of membranes within the cell (ENDOPLASMATIC NET) and the double membrane around the cell ... ... Scientific and technical encyclopedic dictionary

MEMBRANE, membranes, for women (lat. membrana membrane) (physical, technical). A membrane fixed along the edges or a thin plate of elastic material, capable of making the vibrations necessary to capture and reproduce sound waves. Dictionary… … Explanatory Dictionary of Ushakov

MEMBRANE, s, female. An elastic membrane, a thin film or plate capable of vibrating. M. phone. | adj. membrane, oh, oh. Membrane musical instruments. Explanatory dictionary of Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov

MEMBRANE, or membrane, a thin plate of any substance. It is used in acoustics to reproduce sound vibrations. The presence of natural vibrations in acoustic M. distorts the nature of the sound. In colloidal chemistry, M. is used for ... ... Big Medical Encyclopedia

Modern manufacturers, possessing innovative technologies, are able to offer the latest developments in membrane materials that are used in a wide variety of areas of human activity. What is membrane clothing? This is a high-tech material, which, due to its qualities, is used for sewing sports, casual and outdoor clothing. The clothing industry offers clothes not only for adults, but also for children.

The main trends in the development of the modern economy include the improvement of product quality. This is achieved through the introduction of innovative methods in production. Today, clothing made of fabric with a membrane coating is very popular. The range of products made from this material is very large.

It is made from:

• Membrane clothing and footwear for people involved in active sports, tourism;
• Special clothing for firefighters and medical workers;
• Uniform for military personnel and kits for winter fishing.

Membrane material appeared relatively recently. Over the past 10 years, he has gained worldwide fame. Items made from this material must meet the requirements: to show protective properties during the period of atmospheric influences and to provide a comfortable feeling in the underwear space. In case of heavy load, the material is able to remove excess moisture and heat. To obtain a fabric with a thickness of 10-30 microns, extrusion methods, coagulation or thermal biaxial stretching are used.

To connect the membrane to the fabric, polyurethane is used for adhesion, which is coated with an atmospheric-active film. It passes along with the web through the pressure rollers of the calender, which allows the two materials to be glued together.

When designing and creating professional membrane clothing for children and adults in winter, designers try to cope with a multifaceted and complex task, to combine all the characteristics of the material in the product:

• Aesthetic appearance;
• Comfort fit;
• Insertion of reflective elements with optical recognition into children's membrane clothing;
• Clothing for tourism made of membrane material should have a long service life;
• High-quality atmospheric laminates can affect the membrane, which, in turn, affects the comfortable well-being of people in the winter.

How to distinguish the material? Winter clothing has common key indicators:

1. Water resistance - this indicator is characterized by the height of the water level and the ability of the membrane to withstand it without letting it inside. Moisture content measurement is calculated in millimeters or other units such as PSI (POUND PER SGUARE INCH). This measurement means weight in pounds per inch². Studies have shown that if the material has a PSI value of more than 25 units, then the product will be waterproof. With a material index of 1-24 PSI, it is considered that the product has a low resistance to moisture. But this indicator is enough for people who are not involved in extreme sports. Therefore, there is no need to overpay for extra layers of clothing. All layers must be glued so that moisture does not penetrate through them into the product. If the label says "all seams are sealed" ─ this means that the seams of the suit for the winter are completely taped. And if there is an inscription “critical seam sealing” on the label, it means that only the main seams are glued in the kit, and in heavy rain the product may get wet over time;
2. Moisture permeability - if the definition of this characteristic is theoretically clear, then the digital indicators do not say anything to many consumers. This can be used by an unscrupulous manufacturer. He sometimes indicates indicators of clothing for children made of membrane material that absolutely do not correspond to the technical characteristics of the material, which leads to disastrous results during testing.

Testing is based on measuring the amount of liquid in grams that can evaporate per day in m² (g / m² / 24 h) ─ this is the MVTR indicator moisture vapor transmission rate ─ moisture vapor transmission rate. These tests are carried out by special laboratories. The main thing that consumers should remember is that the MVTR B2 marking for the test is considered universal. The membrane is a fragile and thin material. The sheet version is applied to the final product. If the membrane is applied in liquid form, then it is applied to the base material and forms a membrane coating, which received the second name ─ laminate.

The main types of membrane material:

• 2l - two-layer view is marked with the value 2L. The sheet material is applied to the fabric. In a two-layer product, the advantage is economical weight, high moisture permeability. The product is duplicated by an inner lining, which is made of mesh. You can use two-layer clothing during sports, as well as for everyday use;
• 5l - two and a half layers. It consists of two layers, between which there is an additional protective layer of non-woven material. Ski clothing made from this brand of material is light and compact. The membrane is protected by the outer layer, on which there are rubber "pimples" with a diameter of less than 1 mm. The membrane does not come into contact with clothing and protects it from various damages. This does not prevent the product from retaining all the properties of the three-layer Gore-Tex material and gaining weight. For example, Millet's Paclite jacket weighs only 470g;
• 3l - three-layer type. In this design, the membrane is protected by fabric on both sides. All products are highly durable. It can be used for sports and special kits designed for use in extreme conditions.

clothing features

Clothing made of the membrane does not get wet, reliably protects against gusty winds, cold weather, perfectly “breathes”, thereby creating comfortable conditions for wearing.

For children

An excellent option for outerwear in the cold season is membrane children's clothing. When the baby takes his first steps in winter, he is not very comfortable walking in bulky fur overalls. Heavy sets hamper movement, so they try to buy light, functional, comfortable membrane winter clothes for children. High-quality outerwear can be combined with properly selected underwear, which can provide the baby with comfortable, warm and dry wearing in any bad weather ─ snowy winter down to -20˚C or a rainy autumn day. In addition, the membrane fabric is endowed with dirt-repellent qualities. Almost all children's clothing is different:

• wear resistance;
• Persistent colors;
• Decor with reflective inserts.

For the above properties, there is a corresponding marking on the label. For example, an indicator of 3000-15000 mm of water column indicates the intensity of rain, at which the coating will begin to let moisture through. Laboratory studies show that with an indicator of 4 thousand mm of water, children's things do not let moisture through and the child always remains warm and dry.

Brands that produce membrane clothing and shoes for children:

• Reima - for its products, the company uses high quality insulation that provides warmth in severe frosts. Parents from the whole variety of styles and colors can choose the best design for their baby;
• Ketch is a newly created Swedish company that has already become popular in the market. Buyers claim that under the clothes of this company there is no need to wear other warm clothes;
• Gore-Tex is an American company that has developed durable, breathable footwear. If the label says "Gore-Tex", parents can be confident in the quality of the product;
• Sumpa Tex - a German company introduced footwear products without membrane pores. In this model range, moisture is removed from the warm side of the membrane material to the cold side. She is not afraid of dirt, and reagents do not spoil the appearance of the product.

Top sellers of children's membrane clothing:

• Winter set Reima 513100-4901 Misteli is a model for a girl with a comfortable design. The set consists of a jacket and semi-overalls. It has a waterproof and non-breathable fabric with a dirt-repellent impregnation. The presence of fluffy Comfort + insulation with high elasticity, gives the product volume. The price of the model is 6 thousand rubles;
• Winter jacket for girls Sisarus Reimatec 531300-4190 - a combination of design, quality and practicality will appeal to parents and children. The material is breathable, the hood is removable, the material is dirt-repellent. The price of the model is 8038 rubles;
• Ricosta shoes - a German manufacturer uses only natural and high-tech materials for children's shoes. The price of the model is 2850 rubles;
• Boots Kotofey 454968-42 - the model is decorated with snowflakes, has two Velcro fasteners. Phylon material is used for the sole. Fur serves as an internal insulation. The price of the model is 2500 rubles;
• Ketch set (art. 090254-090255) - the model consists of a jacket and overalls. Designed for t from + 6˚ to - 28˚С. The price of the kit is up to 4000 rubles.

For adults

Today, membrane clothing for women and men is used not only for hiking, outdoor activities and skiing in ski resorts. You can wear it in ordinary city life. Products allow you not to freeze at a temperature of -15-20˚С and not to sweat in a warm, closed room. Material properties will be respected in case of multi-layering.

Do not wear clothes that absorb moisture or that do not “breathe” well. Since 1959, the American company W. L. Gore & Associates began experimenting with polytetrafluoroethylene for the manufacture of this material, and only in 1976 was a fabric with a water-repellent, windproof, "breathable" effect created.

When creating membrane clothing for hunting, manufacturers use modern fabric, in which a large number of micro-holes - up to 1.4 million pieces are located per 1 cm². This porous layer is located between the upper and inner layers. This design is used not only for clothes, but also for adult shoes. The holes are 20,000 times smaller than a drop of water. Moisture is expelled through them in the form of steam. You can winter in membrane clothing, it is lightweight and folds compactly.

Companies that manufacture membrane suits:

• Norfin - membrane suits of the Latvian company, light, comfortable, have high water resistance. Warmer for fishing, no clothes for hunting. In the hunting collection, the cost of products reaches $ 300-400;
• Red Fox - a well-known Russian manufacturer has gained popularity in the market due to its quality and affordable prices;
• Dupont is an American manufacturer that has not yet become widely known among outerwear manufacturers, but is proud of its underwear products ─ unique socks that not only retain heat, “breathe”, but also do not let moisture in from the outside. The price of these socks is $25. Use wearable membrane clothing for hunting.

Consider some models of adult membrane clothing:

• Norfin Extreme 2 XXL (309105-XXL) - the model is designed for fishermen, as well as lovers of new technologies use membrane clothing for hunters. Which withstands frost at -32˚С. The straps in the model are adjustable, the waist is tightened with a latch, the knee pads consist of additional soft inserts, a zipper is inserted on the bottom of the semi-overalls. Price 5500 rubles;
• Pea jacket Atax - the model is designed for climbers. The base consists of a double synthetic winterizer with two chest pockets and other additional elements that distribute the necessary load. The membrane coating has a pixel atax color. The knitted collar has a windproof placket. The average price is from 2700 rubles;
• Neve Astra - women's and men's trousers made of Evapora membrane fabric. They are waterproof and keep out the cold. Adjustable throughout the length of the trousers. All seams are taped and have pockets with zippers. The average price is from 2500 rubles;
• Norfin Scandic suit - the model belongs to rain suits. Able to provide a comfortable stay in various weather conditions. The product has many pockets, the bottom of the jacket is pulled together, has a mesh lining and other additional elements. Price 9500 rubles;
• Jacket Armani Women Jacket 281408 - this model is designed for women who go in for skiing. It is windproof and waterproof. Additional high-quality, insulated elements with knitted cuffs allow you to feel comfortable. The price of the jacket is from 39 thousand rubles.

Choice by season

Modern membrane products will help protect against frost or strong winds. In order for clothes to be comfortable and please with warmth, you need to make the right choice. Whatever season clothes are purchased for, you need to consider some rules:

1. It is important to pay attention to product design. The cut should be comfortable and fit the size grid;
2. Winter sets are bought a little loose so that they do not hinder movement and better retain heat;
3. Pay attention to the quality of the seams. It is necessary to exclude uneven lines, raw cuts, protruding threads. This indicates a low quality and a bad reputation of the manufacturer;
4. When choosing winter or demi-season clothing, experts recommend purchasing a 2.5-layer membrane. Since 2-layer is considered short-lived, 3-layer has a significant weight, which will make it difficult for both adults and children to move.

How to wear membrane clothing so that it works correctly, pleases not only with its functionality, but also with its aesthetic appearance? The main thing in operation is layering:

• The first layer is underwear;
• The second layer is insulation;
• The third layer is outerwear (jacket, pants, overalls).

It is undesirable to wear all things made of natural materials, as they tend to absorb moisture. And you need to remember: the membrane works only during the period of active human activity.

In spring and autumn, it is advisable to use thermal underwear. And at -5˚ you need to warm up by wearing a woolen or fleece suit.

Additional functions

• Additional ventilation. Membrane clothing for men has good vapor permeability, but no consumer will refuse additional ventilation of the suit. It can be represented by the presence of "pit-zips" of lightning. Additional ventilation takes place in membrane clothing for hunting in places where there is no direct rain. It can be a zipper that is inserted into the inside of the sleeve, passing through the armpit and down the side seam. And in trousers, the zipper is inserted into the inner side of the thigh. If the temperature rises, it can be unfastened. The entire thermoregulation of the entire membrane structure depends on the length of the zipper;
• Mesh lined pockets. In some models, manufacturers use pockets based on a mesh lining. It provides additional ventilation;
• Self-dumping trousers. This function is found in tourist, mountaineering, skitouring / freeride equipment. The model has excellent ventilation. And the design itself has the property of quickly putting on or removing an extra layer, focusing on the weather, without removing shoes;
• Additional processing. By treating the material with a liquid with fluorine, a protective film is formed on the structure, which repels moisture, but allows air to pass through. The fabric is not afraid of external pollution and ultraviolet;
• Fleece or soft inserts. Eliminate the contact of the membrane with the human body, increase its durability;
• Visor made of flexible material. The element covers the face in windy, rainy weather or during snowfall;
• Snow skirt. Additional protection piece for severe cold weather, used for climbing and other activities.

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