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chitin is, chitinous cover
(C8H13NO5)n (French chitine, from ancient Greek χιτών: chiton - clothing, skin, shell) is a natural compound from the group of nitrogen-containing polysaccharides. Chemical name: poly-N-acetyl-D-glucose-2-amine, a polymer of N-acetylglucosamine residues linked by b-(1,4)-glycosidic bonds.

The main component of the exoskeleton (cuticle) of arthropods and a number of other invertebrates, it is part of the cell wall of fungi and bacteria.

• 1. History
• 2 Distribution in nature
• 3 Physical properties
• 4 Chemistry of chitin
• 5 Practical use
• 6 See also
• 7 Links

Story

In 1821, the Frenchman Henri Braconneau, director of the botanical garden in Nancy, discovered a substance in mushrooms that was insoluble in sulfuric acid. He called it fungin. Pure chitin is isolated for the first time from the outer shells of tarantulas. The term was proposed by the French scientist A. Odier, who studied the outer cover of insects, in 1823.

Distribution in nature

Chitin is one of the most common polysaccharides in nature; every year on Earth, about 10 gigatons of chitin are formed and decomposed in living organisms.

• Performs protective and supporting functions, ensuring cell rigidity - found in the cell walls of fungi.
• The main component of the exoskeleton of arthropods.
• Chitin is also formed in the bodies of many other animals - various worms, coelenterates, etc.

In all organisms that produce and use chitin, it is not found in pure form, but in combination with other polysaccharides, and is very often associated with proteins. Despite the fact that chitin is a substance very similar in structure, physicochemical properties and biological role to cellulose, chitin could not be found in organisms that form cellulose (plants, some bacteria).

Physical properties

Hard translucent.

Chemistry of chitin

In their natural form, chitins from different organisms differ somewhat in composition and properties. The molecular weight of chitin reaches 260,000.

Chitin is insoluble in water and resistant to dilute acids, alkalis, alcohol and other organic solvents. Soluble in concentrated solutions of some salts (zinc chloride, lithium thiocyanate, calcium salts) and in ionic liquids.

When heated with concentrated solutions of mineral acids, it is destroyed (hydrolyzed).

Practical use

One of the derivatives of chitin, obtained from it industrially, is chitosan. The raw materials for its production are crustacean shells (krill, king crab), as well as products of microbiological synthesis. The problems of production of chitin products and its practical use are dealt with by the Russian Chitin Society.

see also

• Chitinases
• Polysaccharides

Links

1. Life after death for empty shells: Crustacean fisheries create a mountain of waste shells, made of a strong natural polymer, chitin. Now chemists are helping to put this waste to some surprising uses, Stephen Nicol, New Scientist, Issue 1755, February 09, 1991.
2. Website of the Russian Chitin Society

Carbohydrates
Are common:	Aldoses Ketoses Furanoses Pyranoses
Geometry	Anomeres Mutarotation Haworth projection
Monosaccharides	Dioses Aldodiose (Glycolaldehyde) Trioses Ketotriose (Dihydroxyacetone) Aldotriose (Glyceraldehyde) Tetroses Ketoterose (Erythrulose) Altotetrose (Erythrose, Throse) Pentoses Ketopentoses (Ribulose, Xylulose) Aldopentoses (Ribose, Arabinose, Xylose, Lyxose, Apiose) Deoxysaccharides (Deoxyribose) Hexose Ketohexoses (Psicose, Fructose, Sorbose, Tagatose) Aldohexoses (Allose, Altrose, Glucose, Mannose, Gulose, Idose, Galactose, Talose) Deoxysaccharides (Fucose, Fuculose, Rhamnose) Heptoses Ketoheptoses (Sedoheptulose, Mannoheptulose) >7 Octoses Nonoses (Neuramic acid) Sialic acids (N-acetylneuraminic acid)
Multisaccharides	Disaccharides Sucrose · Lactose · Maltose · Nigerose · Trehalose · Turanose · Cellobiose · Melibiose · Genciobiose · Vicianose · Rutinose Trisaccharides Raffinose · Melitose · Maltotriose · Gentianose · Solatriose · Cellotriose · Erlose Tetrasaccharides Acarbose Stachyose Oligosaccharides Fructooligosaccharides Galactooligosaccharides Mannanoligosaccharides Isomaltanoligosaccharides Maltodextrin Polysaccharides Glycogen · Starch · Cellulose · Amylose · Amylopectin · Sachylose · Fructans (Inulin, Levan) · Dextran · Pectin · Galactan · Mannan · Xylan · Araban · Galactomannan · Agarose · Lichenin · Pullulan
Carbohydrate derivatives

Skeleton
Exoskeleton	Inorganic: Shell (of many protozoa, molluscs) Organic: Cuticle ( chitinous arthropod shell)
Endoskeleton	Axial (vertebral column (spine), skull, rib cage) Additional (belt of upper limbs upper limbs belt of lower limbs lower limbs)
Hydroskeleton	Formation of eight-rayed polyps
see also	Skeletal revolution Human skeleton List of bones of the human skeleton Musculoskeletal system

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Chitin Information About

Structural formula of the chitin molecule

Chitin is a natural compound from the group of nitrogen-containing polysaccharides. Chemical name: poly-N-acetyl-D-glucose-2-amine, a polymer of N-acetylglucosamine residues linked together by b-glycosidic bonds.

The main component of the exoskeleton of arthropods and a number of other invertebrates, it is part of the cell wall of fungi and bacteria.

Story

In 1821, the Frenchman Henry Bracon, director of the botanical garden in Nancy, discovered a substance in mushrooms that was insoluble in sulfuric acid. He called it fungin. Pure chitin is isolated for the first time from the outer shells of tarantulas. The term was proposed by the French scientist A. Odier, who studied the outer cover of insects, in 1823.

Distribution in nature

Chitin is one of the most common polysaccharides in nature; every year on Earth, about 10 gigatons of chitin are formed and decomposed in living organisms.

• Performs protective and support functions, ensuring cell rigidity; found in the cell walls of fungi.
• The main component of the exoskeleton of arthropods.
• Chitin is also formed in the bodies of many other animals - various worms, coelenterates, etc.

In all organisms that produce and use chitin, it is not found in pure form, but in combination with other polysaccharides, and is very often associated with proteins. Despite the fact that chitin is a substance very similar in structure, physicochemical properties and biological role to cellulose, chitin could not be found in organisms that form cellulose.

Main component of the shell of insects, crustaceans and other arthropods

First letter "x"

Second letter "i"

Third letter "t"

The last letter of the letter is "n"

Answer for the question "The main component of the shell of insects, crustaceans and other arthropods", 5 letters:
chitin

Alternative crossword questions for the word chitin

Organic substance that makes up the outer hard covering of crustaceans, insects and other arthropods and which is found in the membranes of a number of fungi and some types of green algae

Outer hard cover of arthropods

Crayfish shell material

Organic matter that makes up the outer hard covering of crustaceans and insects

"Body armor" of beetle wings

Definition of the word chitin in dictionaries

Encyclopedic Dictionary, 1998 The meaning of the word in the dictionary Encyclopedic Dictionary, 1998
a polysaccharide formed by amino sugar residues of acetylglucosamine. The main component of the exoskeleton (cuticle) of insects, crustaceans and other arthropods. In mushrooms it replaces cellulose, with which it is similar in chemical and physical properties and biological...

Wikipedia Meaning of the word in the Wikipedia dictionary
Chitin is a natural compound from the group of nitrogen-containing polysaccharides. Chemical name: poly-N-acetyl-D-glucose-2-amine, a polymer of N-acetylglucosamine residues linked by β-(1→4)-glycosidic bonds. The main component of the exoskeleton (cuticle...

New explanatory dictionary of the Russian language, T. F. Efremova. The meaning of the word in the dictionary New explanatory dictionary of the Russian language, T. F. Efremova.
m. Organic substance that makes up the outer hard covering of crustaceans, insects and other arthropods and which is found in the membranes of a number of fungi and some types of green algae.

Great Soviet Encyclopedia The meaning of the word in the dictionary Great Soviet Encyclopedia
(French chitine, from Greek chiton ≈ clothing, skin, shell), a natural compound from the group of polysaccharides; the main component of the exoskeleton (cuticle) of arthropods and a number of other invertebrates; it is also part of the cell wall of fungi and bacteria....

Examples of the use of the word chitin in literature.

The beast lay nearby - shackled in a thick chitin, large-headed, with short thick breasts, more like horns, compound eyes.

The second chrysalid ran into the barrier wall of Vega and the Irish woman, even from him chitin there was none left, everything turned to greasy ashes.

The skin has turned into chitin, cuticle, on a tanned face, blue eyes seemed surprisingly bright and large.

During the transition to upright walking, evolution developed supporting structures in the body, and on the outside there was a combination of larval skin and pale chitin.

She clasped her right hand with her left, running her fingers along the beads chitin, which were her identification mark: Raen, Sept Sul, Met-maren, Contrin.

Capsule-type exoskeleton concept for emergency rescue operations

Zeltser A. G.1, Vereikin A. A.1, *, Goykhman A. V.1, Savchenko A. G.1, Zhukov A. A.1, Demchenko M. A.1

UDC: 21.865.8, 623.445.1, 623.445.2

1 Russia, MSTU im. N.E. Bauman

Introduction

The currently existing models of exoskeletons are a frame-type structure that has a minimum of connections with the human body. Thus, the exoskeleton of the lower extremities BLEEX is secured with straps to the feet, legs and back of the human operator, and it is rigidly attached only to the feet.

A fundamentally new concept of the exoskeleton actuator (AM) is proposed, which is based on the idea that in addition to increasing the physical capabilities of a person, the AM should also provide protection for his body, which is quite justified in the non-deterministic conditions of emergency rescue operations. The task has been set to ensure the creation of a universal design of the IM, which will allow, if necessary, to create a line of exoskeletons, which will include a version intended for combat operations. In this case, the power frame is replaced by an armored frame.

1. Determining the relative position of joints

IN As a preliminary stage in the synthesis of the tree-like kinematic diagram of the exoskeleton MI, active and passive degrees of mobility were outlined. By active we mean controlled degrees of mobility, and by passive we mean uncontrolled degrees. A preliminary diagram of the placement of the MI joints was obtained (Fig. 1) and the ranges of variation of the generalized coordinates in the joints were selected, which need to be clarified in the future, based on previous works and anthropometric data (including those proposed by the ergonomic design module of the CATIA software package). Preliminary dimensions of the exoskeleton and location have also been determined

nodes relative to each other. At this stage, the frame design was not worked out.

Rice. 1. Preliminary layout of the joints of the MI exoskeleton

2. Development of the general concept of the actuator

When studying the relative position of the main components, problems were identified that accompany the chosen capsule design, associated with the rigid connection of the structure’s movements to human movements. Thus, for the degree of mobility of the femoral link of the exoskeleton, an adduction-abduction type movement (change in roll), implemented through a cylindrical hinge based on a standard bearing assembly, leads to penetration of the MI link into the human body, which is completely unacceptable. In modern models of exoskeletons, problems of this kind are solved:

 removing the MI link from the human body in a direction perpendicular to the sagittal plane;

 assigning a range of change in the generalized joint coordinate that is significantly less than the permissible one determined from anthropometric parameters;

 strong separation in space of the axes of rotation of the joints, ensuring a change in the position of the hip in roll and pitch.

The previously accepted concept does not allow solving problems using the above methods. A solution has been proposed, which consists in the use of hinges with virtual

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mi axes of rotation coinciding with the axes of rotation of the corresponding human joints. Schematic diagrams of units corresponding to the accepted concept have been developed. Let's take a closer look at the back and hip of the MI exoskeleton.

2.1 Degrees of back mobility

The human back has high mobility, but the concept underlying modern exoskeletons does not allow its mobility to be fully realized. MI significantly limits the movements of the human operator corresponding to changes in the yaw position of the back.

Placing a simple cylindrical hinge behind the back does not solve the problem (Fig. 2). The spine in this case is the axis of rotation, therefore, when placing a rotation pair outside the body, we get a second axis that does not coincide with the first, which can lead to damage to the operator’s spine and body.

Rice. 2. Kinematic diagram of the back of the exoskeleton actuator

The way out of this situation is to use an articulation with a virtual axis of rotation that coincides with the axis of rotation of the human back, which is the spine. In Fig. Figure 3 shows the schematic structure of the spinal unit, which is a rolling guide curved along a certain radius corresponding to the distance to the virtual axis of rotation (item 1).

http://engbul.bmstu.ru/doc/760793.html

Rice. 3. Design diagram for the implementation of a joint that provides a change in the yaw of the operator’s back based on a cylindrical joint with a virtual axis of rotation

2.2 Degrees of hip mobility

The joint responsible for implementing the movement that ensures a change in the position of the human operator’s thigh in pitch, when the position of the person’s leg changes in roll, penetrates into the human body, thereby damaging it. The solution to this problem is the use of a cylindrical hinge with a virtual axis of rotation (items 1, 2 in Fig. 4).

Rice. 4. Design diagram of the implementation of the joint that provides a change in the yaw of the operator’s back

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3. Advantages and disadvantages of the proposed concept

The proposed general concept of the MI exoskeleton has a number of advantages:

 reduced dimensions due to the tight fit of the MI to the human operator’s body;

 With regard to basic human movements, it is possible to implement the principle of one movement of the operator - one movement of the exoskeleton, i.e. the change in the generalized coordinate in the articulation of the IM is adequate to the change in the generalized coordinate of the corresponding human joint. In modern versions of exoskeletons, a change in the generalized coordinates of one human joint corresponds to a certain set of changes in the generalized coordinates of the exoskeleton joints. However, it should be noted that this principle does not apply to all human movements, otherwise it would be necessary to greatly complicate the design of the MI and bring the number of degrees of mobility of the exoskeleton to the number of degrees of mobility of a person, which is not possible at this stage of technology development;

 some simplification of the control system due to the implementation of the principle of one movement of the operator - one movement of the exoskeleton;

 simplified mastery of IM human operator;

 improved ergonomics;

 the ability to modify the frame into an external load-bearing armored structure designed to protect against various shock loads;

 relatively lightweight design due to the fact that the armor and frame are a single whole;

 high structural rigidity.

 Among the disadvantages of the concept are:

 increase in degrees of mobility of the infarction;

 complication of the design of joints;

 increased energy consumption.

4. Developed actuator mechanism of the lower limb exoskeleton

The next stage after deciding on the use of virtual axes and developing the design diagrams of the IM joints is the development of a kinematic diagram taking into account the real and virtual axes of rotation. To obtain the exact geometric dimensions of the kinematic diagram of the exoskeleton MI, several solution methods were considered:

 full x-ray of the operator's body;

 assembly of a prototype of a kinematic model for its experimental refinement.

http://engbul.bmstu.ru/doc/760793.html

Finally, the second method was chosen. At the same time, it was decided to combine the stages of developing the frame and assembling the experimental model. In Fig. Figure 5 shows a preliminary version of the capsular type MI exoskeleton of the lower extremities.

Advantages of the proposed design of the MI exoskeleton:

 simple and convenient arrangement of joints, including with a virtual axis of rotation;

 suitable for making an experimental model of the kinematic diagram of an IM in order to clarify the geometric dimensions and placement of degrees of mobility;

 removal from the actuator motors, which are currently considered pneumatic and hydraulic motors with translational movement of the output link, of all loads except the axial one, due to the movement of the output link along the guide;

 The executive motor is reliably protected from external mechanical influences by a casing, which is especially valuable when using pneumatic muscles as executive motors. This is achieved by introducing an additional lever connecting the output link of the actuator motor with the IM (Fig. 5);

 An increase in the service life of pneumatic muscles is achieved due to the fact that they do not bend during operation.

Rice. 5. Preliminary version of the exoskeleton actuator of the lower extremities of the capsule type

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5. Power plant

Modern exoskeletons can have sufficient autonomy only if the total power of the actuators is low, which affects, on the one hand, the load capacity and speed of movement in space, and the number of controlled degrees of mobility, on the other. Largely due to the last factor, the currently existing autonomous MIs are exoskeletons of the lower extremities only. The exoskeleton of the lower extremities BLEEX uses an internal combustion engine (ICE) as the main source of energy, generating hydraulic and electrical energy.

IN The possibility of using an internal combustion engine combined with a hydraulic or pneumatic supercharger is currently being explored. This should significantly reduce the weight and size characteristics of the power unit.

IN In modern models of autonomous exoskeletons equipped with internal combustion engines, the engines are located behind the operator’s back in large backpacks, which reduces the mobility of the lumbar region, but, at the same time, allows the use of a larger engine, simultaneously providing back protection. It is possible to use the principle that is used on the Israeli army's Merkava tanks. The engine is located at the front, providing additional protection for the crew. To reduce the size of the suit, you can use an engine V-shaped configuration with a greatly increased camber angle. This configuration will literally allow the engine to lie flat on the chest or back, thereby significantly reducing the dimensions.

Conclusion

All highly developed countries of the world are working on projects of robotic exoskeletons equipped with powerful actuators, intended for use mainly in combat zones and emergency rescue operations. Developments in this direction are also underway in the Russian Federation, but at the moment the prospects for domestic developments seem very vague. Thus, there is an urgent need to conduct scientific research and implement technical projects in this area.

To date, the concept of the MI exoskeleton has been defined, and some design solutions have been worked out. A method is presented that allows one to calculate the dynamics of the MI taking into account the reactions of the supporting surface, and subsequently build a control system for the human-exoskeleton complex. The parallel design of two versions of the IM, which have a universal frame design, but differ in terms of actuators: hydraulic cylinders and pneumatic muscles, was chosen as priority directions for the development of this project. Currently, work is also underway on an experimental mock-up, which will allow us to evaluate the selected solutions.

http://engbul.bmstu.ru/doc/760793.html

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