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State autonomous educational institution

secondary vocational education -

Novokuybyshevsk State College of Humanities and Technology

Essay

by discipline:"Chemistry"

topic: “The use of radioactive isotopes in technology”

Grazhdankina Daria Igorevna

1st year students group 16

specialty 230115

2013

1. What are isotopes and their production

Bibliography

radioactive isotope atom flaw detection

1. What are isotopes?

Isotopes are varieties of any chemical element in the periodic table D.I. Mendeleev, having different atomic weights. Different isotopes of any chemical element have the same number of protons in the nucleus and the same number of electrons on the shells of the atom, have the same atomic number and occupy certain places in the D.I. table, characteristic of a given chemical element. Mendeleev. The difference in atomic weight between isotopes is explained by the fact that the nuclei of their atoms contain different numbers of neutrons.

Radioactive isotopes are isotopes of any element of D.I. Mendeleev’s periodic table, the atoms of which have unstable nuclei and pass into a stable state through radioactive decay accompanied by radiation. For elements with atomic numbers greater than 82, all isotopes are radioactive and decay by alpha or beta decay. These are the so-called natural radioactive isotopes, usually found in nature. The atoms formed during the decay of these elements, if they have an atomic number above 82, in turn undergo radioactive decay, the products of which can also be radioactive. It turns out to be a sequential chain, or a so-called family of radioactive isotopes. There are three known natural radioactive families, called after the first element of the series, the families of uranium, thorium and actinouranium (or actinium). The uranium family includes radium and radon. The last element of each series transforms as a result of decay into one of the stable isotopes of lead with serial number 82. In addition to these families, certain natural radioactive isotopes of elements with serial numbers less than 82 are known. These are potassium-40 and some others. Of these, potassium-40 is important, as it is found in any living organism.

Radioactive isotopes of all chemical elements can be obtained artificially.

There are several ways to obtain them. Radioactive isotopes of elements such as strontium, iodine, bromine and others, occupying middle places in the periodic table, are fission products of the uranium nucleus. From a mixture of such products obtained in a nuclear reactor, they are isolated using radiochemical and other methods. Radioactive isotopes of almost all elements can be produced in a particle accelerator by bombarding certain stable atoms with protons or deuterons. A common method of producing radioactive isotopes from stable isotopes of the same element is by irradiating them with neutrons in a nuclear reactor. The method is based on the so-called radiation capture reaction. If a substance is irradiated with neutrons, the latter, having no charge, can freely approach the nucleus of an atom and, as it were, “stick” to it, forming a new nucleus of the same element, but with one extra neutron. In this case, a certain amount of energy is released in the form of gamma radiation, which is why the process is called radiation capture. Nuclei with an excess of neutrons are unstable, so the resulting isotope is radioactive. With rare exceptions, radioactive isotopes of any element can be obtained in this way.

When an isotope decays, an isotope that is also radioactive can be formed. For example, strontium-90 turns into yttrium-90, barium-140 into lanthanum-140, etc.

Transuranium elements unknown in nature with a serial number greater than 92 (neptunium, plutonium, americium, curium, etc.), all isotopes of which are radioactive, were artificially obtained. One of them gives rise to another radioactive family - the neptunium family.

During the operation of reactors and accelerators, radioactive isotopes are formed in the materials and parts of these installations and surrounding equipment. This "induced activity", which persists for a more or less long time after the installations have stopped operating, represents an undesirable source of radiation. Induced activity also occurs in a living organism exposed to neutrons, for example during an accident or an atomic explosion.

The activity of radioactive isotopes is measured in units of curie or its derivatives - millicurie and microcurie.

In terms of chemical and physicochemical properties, radioactive isotopes are practically no different from natural elements; their admixture to any substance does not change its behavior in a living organism.

It is possible to replace stable isotopes in various chemical compounds with such labeled atoms. The properties of the latter will not change as a result, and if introduced into the body, they will behave like ordinary, unlabeled substances. However, thanks to radiation, it is easy to detect their presence in the blood, tissues, cells, etc. The radioactive isotopes in these substances thus serve as indicators, or indicators, of the distribution and fate of substances introduced into the body. That's why they are called "radioactive tracers." A variety of inorganic and organic compounds labeled with various radioactive isotopes have been synthesized for radioisotope diagnostics and for various experimental studies.

2. Application of radioactive isotopes in technology

One of the most outstanding studies carried out using “tagged atoms” was the study of metabolism in organisms. It has been proven that in a relatively short time the body undergoes almost complete renewal. The atoms that make it up are replaced by new ones. Only iron, as experiments on isotope studies of blood have shown, is an exception to this rule. Iron is part of the hemoglobin of red blood cells. When radioactive iron atoms were introduced into food, it was found that the free oxygen released during photosynthesis was originally part of water, not carbon dioxide. The scope of application of radioactive isotopes in industry is extensive. One example of this is the following method for monitoring piston ring wear in internal combustion engines. By irradiating the piston ring with neutrons, they cause nuclear reactions in it and make it radioactive. When the engine operates, particles of ring material enter the lubricating oil. By examining the level of radioactivity in the oil after a certain time of engine operation, ring wear is determined. Radioactive isotopes make it possible to judge the diffusion of metals, processes in blast furnaces, etc.

Powerful gamma radiation from radioactive drugs is used to examine the internal structure of metal castings in order to detect defects in them.

Radioactive isotopes that emit gamma rays can be used instead of bulky X-ray units for transilluminating products, since the properties of gamma rays are similar to the properties of X-rays. A gamma ray source is placed on one side of the product being tested, and photographic film is placed on the other. This testing method is called gamma flaw detection. In this way, ferrous and non-ferrous castings, finished products (steel products up to 300 mm thick) and the quality of welds are currently checked. With the help of radioactive isotopes, it is easy to measure the thickness of a metal strip or rolled metal sheets on the go and without contact and automatically maintain a constant thickness. A source of beta particles is placed under the moving belt running out from under the rollers of the machine. A change in the thickness of the tape therefore leads to a change in the current in the meter. This current is amplified and sent either to a measuring device or to an automatic machine, which will instantly bring the rollers closer together or, conversely, push them apart. Devices of this type are also used in the paper, rubber and leather industries. Radioisotope sources of electrical energy have been created. They use the heat generated in a sample that absorbs radiation. With the help of thermoelements, this heat is converted into electric current. A source weighing several kilograms provides power of several tens of watts for 10 years of uninterrupted operation. Such sources are used to power automatic beacons and automatic weather stations operating in hard-to-reach areas. More powerful sources were installed on Soviet lunar rovers launched to the Moon. They worked reliably at temperatures from -140 to +120.

One of the most outstanding studies carried out using “tagged atoms” was the study of metabolism in organisms. It has been proven that in a relatively short time the body undergoes almost complete renewal. The atoms that make it up are replaced by new ones. Only iron, as experiments on isotope studies of blood have shown, is an exception to this rule. Iron is part of the hemoglobin of red blood cells. When radioactive iron atoms were introduced into food, it was found that the free oxygen released during photosynthesis was originally part of water, not carbon dioxide. Radioactive isotopes are used in medicine both for diagnosis and for therapeutic purposes. Radioactive sodium, injected in small quantities into the blood, is used to study blood circulation; iodine is intensively deposited in the thyroid gland, especially in Graves' disease. By observing radioactive iodine deposition using a meter, a diagnosis can be made quickly. Large doses of radioactive iodine cause partial destruction of abnormally developing tissues, and therefore radioactive iodine is used to treat Graves' disease. Intense cobalt gamma radiation is used in the treatment of cancer (cobalt gun).

List of used literature

1. Gaisinsky M.N., Nuclear chemistry and its applications, trans. from French, M., 1961

2. Experimental Nuclear Physics, ed. E. Segre, trans. from English, vol. 3, M., 1961; INTERNET tools

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Municipal educational institution "Pobedinskaya secondary school" Shegarsky district, Tomsk region

STATE (FINAL) CERTIFICATION OF IX CLASS GRADUATES

ABSTRACT ON PHYSICS

RADIOACTIVITY PHENOMENON. ITS IMPORTANCE IN SCIENCE, TECHNOLOGY, MEDICINE

Completed: Dadaev Aslan, 9th grade student

Supervisor: Gagarina Lyubov Alekseevna, physics teacher

Pobeda 2010

1. Introduction……………………………………………………………...page 1

2. The phenomenon of radioactivity………..……………………….................page 2

2.1.Discovery of radioactivity…………………………………………………….page 2

2.2. Sources of radiation…………………………………………………….. page 6

3. Production and use of radioactive isotopes……………..page 8

3.1.Use of isotopes in medicine……………………........page 8

3.2. Radioactive isotopes in agriculture………………page 10

3.3.Radiation chronometry…………………………………p.11

3.4. Application of radioactive isotopes in industry...p. 12

3.5. The use of isotopes in science……………………………...page 12

4. Conclusion…………………………………………………………...page 13

5. Literature………………………………………………………..page 14

INTRODUCTION

The idea of ​​atoms as immutable tiny particles of matter was destroyed by the discovery of the electron, as well as the phenomenon of natural radioactive decay discovered by the French physicist A. Becquerel. A significant contribution to the study of this phenomenon was made by the outstanding French physicists Maria Sklodowska-Curie and Pierre Curie.

Natural radioactivity has existed for billions of years and is literally everywhere. Ionizing radiation existed on Earth long before the origin of life on it and was present in space before the emergence of the Earth itself. Radioactive materials have been part of the Earth since its birth. Any person is slightly radioactive: in the tissues of the human body, one of the main sources of natural radiation is potassium - 40 and rubidium - 87, and there is no way to get rid of them.

By carrying out nuclear reactions by bombarding the nuclei of aluminum atoms with a-particles, the famous French physicists Frederic and Irene Curie-Joliot managed to artificially create radioactive nuclei in 1934. Artificial radioactivity is fundamentally no different from natural radioactivity and obeys the same laws.

Currently, artificial radioactive isotopes are produced in different ways. The most common is the irradiation of a target (future radioactive drug) in a nuclear reactor. It is possible to irradiate a target with charged particles in special installations where the particles are accelerated to high energies.

Target: find out in which areas of life the phenomenon of radioactivity is used.

Tasks:

· Study the history of the discovery of radioactivity.

· Find out what happens to a substance during radioactive radiation.

· Find out how to obtain radioactive isotopes and where they will be used.

· Develop skills in working with additional literature.

· Perform a computer-based presentation of the material.

MAIN PART

2.The phenomenon of radioactivity

2.1.Discovery of radioactivity

Story radioactivity began with the French physicist Henri Becquerel's work on luminescence and X-rays in 1896.

The discovery of radioactivity, the most striking evidence of the complex structure of the atom .

Commenting on Roentgen's discovery, scientists hypothesize that X-rays are emitted during phosphorescence, regardless of the presence of cathode rays. A. Becquerel decided to test this hypothesis. Wrapping the photographic plate in black paper, he placed on it a bizarrely shaped metal plate coated with a layer of uranium salt. After exposing it to sunlight for four hours, Becquerel developed the photographic plate and saw on it the exact silhouette of a metal figure. He repeated the experiments with large variations, obtaining prints of a coin and a key. All experiments confirmed the hypothesis being tested, which Becquerel reported on February 24 at a meeting of the Academy of Sciences. However, Becquerel does not stop experiments, preparing more and more new options.

Henri Becquerel Welhelm Conrad Roentgen

On February 26, 1896, the weather over Paris deteriorated and the prepared photographic plates with pieces of uranium salt had to be placed in a dark desk drawer until the sun appeared. It appeared over Paris on March 1, and the experiments could be continued. Taking the records, Becquerel decided to develop them. Having developed the plates, the scientist saw silhouettes of uranium samples on them. Not understanding anything, Becquerel decided to repeat the random experiment.

He placed two plates in a lightproof box, poured uranium salt on them, having first placed glass on one of them and an aluminum plate on the other. All this was in a dark room for five hours, after which Becquerel developed the photographic plates. And well, the silhouettes of the samples are clearly visible again. This means that some rays are formed in uranium salts. They look like X rays, but where do they come from? One thing is clear: there is no connection between X-rays and phosphorescence.

He reported this at a meeting of the Academy of Sciences on March 2, 1896, completely confusing all its members.

Becquerel also established that the intensity of radiation from the same sample does not change over time and that new radiation is capable of discharging electrified bodies.

The majority of members of the Paris Academy, after Becquerel’s next report at the meeting on March 26, believed that he was right.

The phenomenon discovered by Becquerel was called radioactivity, at the suggestion of Maria Sklodowska-Curie.

Maria Skłodowska – Curie

Radioactivity - the ability of atoms of some chemical elements to spontaneously emit.

In 1897, Maria, while pursuing her doctoral dissertation, having chosen a topic for research - the discovery of Becquerel (Pierre Curie advised his wife to choose this topic), decided to find the answer to the question: what is the true source of uranium radiation? To this end, she decides to examine a large number of samples of minerals and salts and find out whether only uranium has the property of radiating. Working with samples of thorium, she discovers that, like uranium, it produces the same rays and about the same intensity. This means that this phenomenon turns out to be a property not only of uranium, and it needs to be given a special name. Uranium and thorium were called radioactive elements. Work continued with new minerals.

Pierre, as a physicist, feels the importance of the work and, temporarily leaving the study of crystals, begins to work together with his wife. As a result of this joint work, new radioactive elements were discovered: polonium, radium, etc.

In November 1903, the Royal Society awarded Pierre and Marie Curie one of England's highest scientific awards, the Davy Medal.

On November 13, the Curies and Becquerel received a telegram from Stockholm announcing that the three of them had been awarded the Nobel Prize in Physics for their outstanding discoveries in the field of radioactivity.

The work started by the Curies was taken up by their students, among whom were daughter Irene and son-in-law Frédéric Joliot, who became Nobel Prize laureates for the discovery in 1935 artificial radioactivity .

Irene and Frederic Curie - Joliot

English physicists E. Rutherford And F. Soddy It has been proven that in all radioactive processes mutual transformations of the atomic nuclei of chemical elements occur. A study of the properties of radiation accompanying these processes in magnetic and electric fields showed that it is divided into a-particles, b-particles and g-rays (electromagnetic radiation with a very short wavelength).

E. Rutherford F. Soddy

Some time later, as a result of studying various physical characteristics and properties of these particles (electric charge, mass, etc.), it was possible to establish that the b particle is an electron, and the a particle is a fully ionized atom of the chemical element helium (i.e. an atom helium that has lost both electrons).

In addition, it turned out that radioactivity is the ability of some atomic nuclei to spontaneously transform into other nuclei with the emission of particles.

For example, several varieties of uranium atoms were found: with nuclear masses approximately equal to 234 amu, 235 amu, 238 amu. and 239 amu Moreover, all these atoms had the same chemical properties. They entered into chemical reactions in the same way, forming the same compounds.

Some nuclear reactions produce highly penetrating radiation. These rays penetrate a layer of lead several meters thick. This radiation is a stream of neutrally charged particles. These particles are named neutrons.

Some nuclear reactions produce highly penetrating radiation. These rays come in different types and have different penetrating powers. For example, neutron flux penetrates through a layer of lead several meters thick.

2.2. Sources of radiation

Radiation is very numerous and varied, but we can distinguish about seven its main sources.

The first source is our Earth. This radiation is explained by the presence of radioactive elements in the Earth, the concentration of which varies widely in different places.

The second source radiation - space, from where a stream of high-energy particles constantly falls onto the Earth. The sources of cosmic radiation are stellar explosions in the Galaxy and solar flares.

Third source Radiation are radioactive natural materials used by humans for the construction of residential and industrial premises. On average, the dose rate inside buildings is 18% - 50% greater than outside. A person spends three quarters of his life indoors. A person constantly staying in a room built of granite can receive - 400 mrem/year, from red brick – 189 mrem/year, from concrete – 100 mrem/year, from wood – 30 mrem/year.

Fourth The source of radioactivity is little known to the population, but no less dangerous. These are radioactive materials that humans use in everyday activities.

The inks for printing bank checks include radioactive carbon, which ensures easy identification of forged documents.

Uranium is used to produce paint or enamel on ceramics or jewelry.

Uranium and thorium are used in glass production.

Artificial porcelain teeth are reinforced with uranium and cerium. At the same time, radiation to the mucous membranes adjacent to the teeth can reach 66 rem/year, while the annual rate for the entire body should not exceed 0.5 rem (i.e. 33 times more)

A TV screen emits 2-3 mrem/year per person.

Fifth source – enterprises for transportation and processing of radioactive materials.

Sixth The source of radiation is nuclear power plants. At nuclear power plants,

In addition to solid waste, there are also liquid (contaminated water from reactor cooling circuits) and gaseous waste contained in the carbon dioxide used for cooling.

Seventh The source of radioactive radiation is medical installations. Despite the commonality of their use in everyday practice, the danger of radiation from them is much greater than from all the sources discussed above and sometimes reaches tens of rems. One of the common diagnostic methods is an X-ray machine. So, with radiography of teeth - 3 rem, with fluoroscopy of the stomach - the same, with fluorography - 370 mrem.

What happens to matter during radioactive radiation?

Firstly, the amazing consistency with which radioactive elements emit radiation. Over the course of days, months, years, the radiation intensity does not change noticeably. It is not affected by heating or increased pressure; the chemical reactions into which the radioactive element entered also did not affect the intensity of the radiation.

Secondly, radioactivity is accompanied by the release of energy, and it is released continuously over a number of years. Where does this energy come from? When a substance becomes radioactive, it experiences some profound changes. It was assumed that the atoms themselves undergo transformations.

The presence of the same chemical properties means that all these atoms have the same number of electrons in the electron shell, and therefore the same nuclear charges.

If the charges of the atomic nuclei are the same, then these atoms belong to the same chemical element (despite the differences in their masses) and have the same atomic number in the D.I. table. Mendeleev. Varieties of the same chemical element that differ in the mass of atomic nuclei are called isotopes .

3. Production and use of radioactive isotopes

Radioactive isotopes found in nature are called natural. But many chemical elements occur in nature only in a stable (i.e., radioactive) state.

In 1934, French scientists Irène and Frédéric Joliot-Curie discovered that radioactive isotopes could be created artificially as a result of nuclear reactions. These isotopes were called artificial .

Nuclear reactors and particle accelerators are usually used to produce artificial radioactive isotopes. There is an industry specializing in the production of such elements.

Subsequently, artificial isotopes of all chemical elements were obtained. In total, approximately 2000 radioactive isotopes are currently known, and 300 of them are natural.

Currently, radioactive isotopes are widely used in various fields of scientific and practical activity: technology, medicine, agriculture, communications, military and some others. In this case, the so-called tagged atom method.

3.1.Use of isotopes in medicine

Application of isotopes, one of the most outstanding studies carried out using “tagged atoms” was the study of metabolism in organisms.

With the help of isotopes, the development mechanisms (pathogenesis) of a number of diseases were revealed; They are also used to study metabolism and diagnose many diseases.

Isotopes are introduced into the human body in extremely small quantities (safe for health) and are not capable of causing any pathological changes. They are distributed unevenly throughout the body by blood. The radiation produced during the decay of an isotope is recorded by instruments (special particle counters, photography) located near the human body. As a result, you can get an image of any internal organ. From this image one can judge the size and shape of this organ, the increased or decreased concentration of the isotope in

its various parts. You can also evaluate the functional state (i.e., work) of internal organs by the rate of accumulation and elimination of the radioisotope.

Thus, the state of cardiac circulation, blood flow velocity, and the image of the heart cavities are determined using compounds including isotopes of sodium, iodine, and technetium; isotopes of technetium and xenon are used to study pulmonary ventilation and diseases of the spinal cord; macroaggregates of human serum albumin with an iodine isotope are used to diagnose various inflammatory processes in the lungs, their tumors and for various diseases of the thyroid gland.

Use of isotopes in medicine

The concentration and excretory functions of the liver are studied using Bengal rose paint with an isotope of iodine and gold. Images of the intestines and stomach are obtained using a technetium isotope; the spleen is obtained using red blood cells with a technetium or chromium isotope; Pancreatic diseases are diagnosed using a selenium isotope. All this data allows us to make a correct diagnosis of the disease.

Using the “labeled atoms” method, various abnormalities in the functioning of the circulatory system are also studied and tumors are detected (since it is in them that some radioisotopes accumulate). Thanks to this method, it was discovered that in a relatively short time the human body is almost completely renewed. The only exception is iron, which is part of the blood: it begins to be absorbed by the body from food only when its reserves are depleted.

When choosing an isotope, important issues include the sensitivity of the isotope analysis method, as well as the type of radioactive decay and radiation energy.

In medicine, radioactive isotopes are used not only for diagnosis, but also for the treatment of certain diseases, such as cancer, Graves' disease, etc.

Due to the use of very small doses of radioisotopes, radiation exposure to the body during radiation diagnostics and treatment does not pose a danger to patients.

3.2. Radioactive isotopes in agriculture

Radioactive isotopes are becoming increasingly used in agriculture. Irradiation of plant seeds (cotton, cabbage, radishes, etc.) with small doses of gamma rays from radioactive drugs leads to a noticeable increase in yield. Large doses of radiation cause mutations in plants and microorganisms, which in some cases leads to the emergence of mutants with new valuable properties ( radio selection). This is how valuable varieties of wheat, beans and other crops were developed, and highly productive microorganisms used in the production of antibiotics were obtained.

Gamma radiation from radioactive isotopes is also used to combat harmful insects and for food preservation. “Tagged atoms” are widely used in agricultural technology. For example, to find out which phosphorus fertilizer is better absorbed by a plant, various fertilizers are labeled with radioactive phosphorus. By then examining the plants for radioactivity, it is possible to determine the amount of phosphorus they have absorbed from different types of fertilizer.

The radioactive carbon method has received an interesting application for determining the age of ancient objects of organic origin (wood, charcoal, fabrics, etc.). Plants always contain a beta radioactive isotope of carbon with a half-life of T = 5700 years. It is formed in the Earth's atmosphere in small quantities from nitrogen under the influence of neutrons. The latter arise due to nuclear reactions caused by fast particles that enter the atmosphere from space (cosmic rays). Combining with oxygen, this carbon forms carbon dioxide, which is absorbed by plants, and through them, by animals.

Isotopes are widely used to determine the physical properties of soil

and reserves of plant food elements in it, to study the interaction of soil and fertilizers, the processes of absorption of nutrients by plants, and the entry of mineral food into plants through leaves. Isotopes are used to identify the effect of pesticides on the plant organism, which makes it possible to determine the concentration and timing of their treatment of crops. Using the isotope method, the most important biological properties of agricultural crops are studied (when assessing and selecting breeding material) yield, early ripening, and cold resistance.

IN livestock farming they study the physiological processes occurring in the body of animals, analyze feed for the content of toxic substances (small doses of which are difficult to determine by chemical methods) and microelements. With the help of isotopes, techniques are being developed to automate production processes, for example, separating root crops from stones and lumps of soil when harvesting with a combine on rocky and heavy soils.

3.3.Radiation chronometry

Some radioactive isotopes can be successfully used to determine the age of various fossils ( radiation chronometry). The most common and effective method of radiation chronometry is based on measuring the radioactivity of organic substances, which is caused by radioactive carbon (14C).

Research has shown that for every gram of carbon in any organism, 16 radioactive beta decays occur per minute (more precisely, 15.3 ± 0.1). After 5730 years, in each gram of carbon only 8 atoms per minute will decay, after 11,460 years - 4 atoms.

One gram of carbon from young forest samples emits about fifteen beta particles per second. After the death of the organism, its replenishment with radioactive carbon stops. The available amount of this isotope decreases due to radioactivity. By determining the percentage of radioactive carbon in organic remains, it is possible to determine their age if it lies in the range from 1000 to 50,000 and even up to 100,000 years.

The number of radioactive decays, i.e., the radioactivity of the samples under study, is measured by radioactive radiation detectors.

Thus, by measuring the number of radioactive decays per minute in a certain weight amount of the material of the sample under study and recalculating this number per gram of carbon, we can determine the age of the object from which the sample was taken. This method is used to determine the age of Egyptian mummies, remains of prehistoric fires, etc.

3.4. Application of radioactive isotopes in industry

One example is the following method for monitoring piston ring wear in internal combustion engines. By irradiating the piston ring with neutrons, they cause nuclear reactions in it and make it radioactive. When the engine operates, particles of ring material enter the lubricating oil. By examining the level of radioactivity in the oil after a certain time of engine operation, ring wear is determined. Radioactive isotopes make it possible to judge the diffusion of metals, processes in blast furnaces, etc. Powerful gamma radiation from radioactive preparations is used to study the internal structure of metal castings in order to detect defects in them.

Isotopes are also used in nuclear physics equipment for the manufacture of neutron counters, which makes it possible to increase the counting efficiency by more than 5 times, and in nuclear energy as neutron moderators and absorbers.

3.5. Use of isotopes in science

Use of isotopes in biology led to a revision of previous ideas about the nature of photosynthesis, as well as about the mechanisms that ensure the assimilation by plants of inorganic substances of carbonates, nitrates, phosphates, etc. With the help of isotopes, the movement of populations in the biosphere and individuals within a given population, the migration of microbes, as well as individual compounds within body. By introducing a label into organisms with food or by injection, it was possible to study the speed and migration routes of many insects (mosquitoes, flies, locusts), birds, rodents and other small animals and obtain data on the size of their populations.

In area physiology and biochemistry of plants With the help of isotopes, a number of theoretical and applied problems have been solved: the routes of entry of minerals, liquids and gases into plants, as well as the role of various chemical elements, including microelements, in plant life have been clarified. It has been shown, in particular, that carbon enters plants not only through the leaves, but also through the root system; the paths and speeds of movement of a number of substances from the root system to the stem and leaves and from these organs to the roots have been established.

In area physiology and biochemistry of animals and humans the rates of entry of various substances into their tissues have been studied (including the rate of incorporation of iron into hemoglobin, phosphorus into nervous and muscle tissue, calcium into bones). The use of “labeled” food led to a new understanding of the rates of absorption and distribution of nutrients, their “fate” in the body and helped to monitor the influence of internal and external factors (starvation, asphyxia, overwork, etc.) on metabolism.

CONCLUSION

Outstanding French physicists Maria Sklodowska-Curie and Pierre Curie, their daughter Irene and son-in-law Frédéric Joliot and many other scientists not only made a great contribution to the development of nuclear physics, but were passionate fighters for peace. They carried out significant work on the peaceful use of atomic energy.

In the Soviet Union, work on atomic energy began in 1943 under the leadership of the outstanding Soviet scientist I.V. Kurchatov. In the difficult conditions of an unprecedented war, Soviet scientists solved the most complex scientific and technical problems related to the mastery of atomic energy. On December 25, 1946, under the leadership of I.V. Kurchatov, a chain reaction was carried out for the first time on the continent of Europe and Asia. Began in the Soviet Union era of the peaceful atom.

In the course of my work, I found out that radioactive isotopes obtained artificially have found wide application in science, technology, agriculture, industry, medicine, archeology and other fields. This is due to the following properties of radioactive isotopes:

· a radioactive substance continuously emits a certain type of particle and the intensity does not change over time;

· radiation has a certain penetrating ability;

· radioactivity is accompanied by the release of energy;

· under the influence of radiation, changes can occur in the irradiated substance;

· radiation can be detected in different ways: with special particle counters, photography, etc.

LITERATURE

1. F.M. Diaghilev “From the history of physics and the life of its creators” - M.: Education, 1986.

2. A.S. Enokhin, O.F. Kabardin and others. “Anthology on Physics” - M.: Education, 1982.

3. P.S. Kudryavtsev. “History of Physics” - M.: Education, 1971.

4. G.Ya. Myakishev, B.B. Bukhovtsev “Physics 11th grade.” - M.: Education, 2004.

5. A.V. Peryshkin, E.V. Gutnik "Physics 9th grade." - M.: Bustard, 2005.

6. Internet resources.

Review

for an examination essay in physics “The phenomenon of radioactivity. Its significance in science, technology, medicine."

The author sees the relevance of the chosen topic in the possibility of using nuclear energy for peaceful purposes. Radioactive isotopes obtained artificially have found wide application in various fields of scientific and practical activity: science, technology, agriculture, industry, medicine, archeology, etc.

However, the “Introduction” section does not indicate the relevance and interest of the author in the chosen topic of the abstract.

The discovery of radioactivity is explained in an accessible, logical manner; research carried out using “tagged atoms”.

The formatting of the abstract does not in all cases meet the requirements:

· Pages are not numbered;

· Each section is not printed from a new page;

· There are no references to illustrations in the text;

· The “Literature” section does not list Internet resource sites.

In general, despite minor shortcomings in the compilation and design, we can say that the abstract “The Phenomenon of Radioactivity. Its significance in science, technology, and medicine deserves a “good” rating.

Physics teacher, Municipal Educational Institution "Pobedinskaya Secondary School": ___________/L.A. Gagarin/

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nucleus radioactive isotope analysis

Radioactive isotopes and their applications

Isotopes are varieties of the same chemical element that are similar in their physicochemical properties, but have different atomic masses.

Radioactivity is the transformation of atomic nuclei into other nuclei, accompanied by the emission of various particles and electromagnetic radiation.

In nature, there are both stable isotopes and unstable ones - radioactive ones, the nuclei of atoms of which are subject to spontaneous transformation into other nuclei with the emission of various particles (or radioactive decay processes). About 270 stable isotopes are now known. The number of unstable isotopes exceeds 2000, the vast majority of them are obtained artificially as a result of various nuclear reactions. The number of radioactive isotopes of many elements is very large and can exceed two dozen. The number of stable isotopes is significantly smaller. Some chemical elements consist of only one stable isotope (beryllium, fluorine, sodium, aluminum, phosphorus, manganese, gold and a number of other elements). The largest number of stable isotopes - 10 - was found in tin, in iron, for example, there are 4, and in mercury - 7.

With the help of nuclear reactions, radioactive isotopes of all chemical elements can be obtained. They are produced at electron particle accelerators and nuclear reactors. They are also called “labeled atoms”.

Radioisotope diagnostics is the use of radioactive isotopes and labeled compounds to study human organs and systems in order to recognize diseases. The main method of radioisotope diagnostics is the radioactive indication method, i.e., a method of monitoring radioactive substances introduced into the body.

Radioactive isotopes of a number of chemical elements are sources of ionizing radiation, which can be recorded with a high degree of accuracy using special radiometric and recording devices after the isotope is introduced into the human body. Modern radiological equipment makes it possible to capture and study extremely small quantities of radioactive compounds (so-called indicator quantities), which are practically harmless to the body of the person being examined. By registering the distribution, movement, transformation and excretion of radioactive tracers from the body, the doctor is able to judge the participation of the corresponding elements in biochemical and physiological processes in the body. Among the numerous methods of radioisotope diagnostics, laboratory radiometry, clinical radiometry, clinical radiography and scanning are the most widely used. Radioisotope scanning of internal organs makes it possible to determine the location of the organ under study in the body, establish its shape and size, and identify the presence of a number of pathological changes in it. The main advantage of radioisotope research methods is their complete painlessness and practical safety for the patient with high accuracy of diagnostic results.

One of the most outstanding studies was the study of metabolism in organisms. It has been proven that in a relatively short time the body undergoes almost complete renewal. The atoms that make it up are replaced by new ones. Only iron, as experiments on isotope studies of blood have shown, is an exception to this rule. Radioactive isotopes are used in medicine both for diagnosis and for therapeutic purposes. Radioactive sodium, injected in small quantities into the blood, is used to study blood circulation; iodine is intensively deposited in the thyroid gland, especially in Graves' disease. By observing radioactive iodine deposition using a meter, a diagnosis can be made quickly. Large doses of radioactive iodine cause partial destruction of abnormally developing tissues, and therefore radioactive iodine is used to treat Graves' disease. Intense cobalt gamma radiation is used in the treatment of cancer (cobalt gun).

No less extensive are the applications of radioactive isotopes in industry. One example of this is the following method for monitoring piston ring wear in internal combustion engines. By irradiating the piston ring with neutrons, they cause nuclear reactions in it and make it radioactive. When the engine operates, particles of ring material enter the lubricating oil. By examining the level of radioactivity in the oil after a certain time of engine operation, ring wear is determined. Radioactive isotopes make it possible to judge the diffusion of metals, processes in blast furnaces, etc.

Powerful gamma radiation from radioactive drugs is used to examine the internal structure of metal castings in order to detect defects in them.

Radioactive isotopes are increasingly used in agriculture. Irradiation of plant seeds (cotton, cabbage, radishes, etc.) with small doses of gamma rays from radioactive drugs leads to a noticeable increase in yield. Large doses of radiation cause mutations in plants and microorganisms, which in some cases leads to the appearance of mutants with new valuable properties (radio selection). This is how valuable varieties of wheat, beans and other crops were developed, and highly productive microorganisms used in the production of antibiotics were obtained. Gamma radiation from radioactive isotopes is also used to control harmful insects and for food preservation. Radioactive isotopes are widely used in agricultural technology. For example, to find out which phosphorus fertilizer is better absorbed by the plant, various fertilizers are labeled with radioactive phosphorus 15 32P. By then examining the plants for radioactivity, it is possible to determine the amount of phosphorus they have absorbed from different types of fertilizer.

Radiocarbon dating is a physical method of dating biological remains, objects and materials of biological origin by measuring the content of the radioactive isotope 14C in the material relative to stable isotopes of carbon. An interesting application of radioactivity is the method of dating archaeological and geological finds by the concentration of radioactive isotopes. An unstable isotope of carbon appears in the atmosphere due to nuclear reactions caused by cosmic rays. A small percentage of this isotope is found in the air along with the regular stable isotope. Plants and other organisms take up carbon from the air and accumulate both isotopes in the same proportions as in the air. After the plants die, they stop consuming carbon and the unstable isotope, as a result of β-decay, gradually turns into nitrogen with a half-life of 5730 years. By accurately measuring the relative concentration of radioactive carbon in the remains of ancient organisms, the time of their death can be determined. This method is used to determine the age of Egyptian mummies, remains of prehistoric fires, etc.

The radioactive method of analyzing a substance makes it possible to determine the content of various metals in it, from calcium to zinc, in extremely low concentrations - up to 1-10g. (only 10-12 g of substance is required). Radioactive drugs are widely used in medical practice to treat many diseases, including malignant tumors. Isotopes of plutonium-238 and curium-224 are used to produce low-power batteries for heart rhythm stabilizers. For their continuous operation for 10 years, only 150-200 mg of plutonium is enough (conventional batteries last up to four years).

Radioisotope energy sources are devices of various designs that use the energy released during radioactive decay to heat the coolant or convert it into electricity. A radioisotope energy source is fundamentally different from a nuclear reactor in that it uses not a controlled chain reaction, but the energy of the natural decay of radioactive isotopes. Radioisotope energy sources are used where it is necessary to ensure autonomy of equipment operation, significant reliability, low weight and dimensions. Currently, the main areas of application are space (satellites, interplanetary stations, etc.), deep-sea vehicles, remote areas (the Far North, the open sea, Antarctica). In general, simply put, studying “deep space” without radioisotope generators is impossible, since at a significant distance from the Sun the level of solar energy that can be used through photocells is small. For example, in the orbit of Saturn, the illumination of the Sun at its zenith corresponds to earthly twilight. In addition, at a significant distance from the Earth, transmitting radio signals from a space probe requires very high power. Thus, the only possible source of energy for spacecraft in such conditions, in addition to a nuclear reactor, is a radioisotope generator. Existing Applications:

· Interstellar probes: Electrical heat supply for spacecraft.

· Medicine: power supply for pacemakers, etc.

· Power supply of beacons and buoys.

Promising areas of application:

· Android robots: Electrical heat supply. As the main source of energy.

· Space-based combat lasers: Laser pumping and electrical heat supply.

· Combat vehicles: Powerful engines with a long service life (unmanned reconnaissance vehicles - aircraft and mini-boats, power supply for combat helicopters and aircraft, as well as tanks and autonomous launchers).

· Deep-sea hydroacoustic stations: long-term power supply of non-recovery vehicles.

Radioactive isotopes and compounds labeled with radioactive isotopes are widely used in a wide variety of areas of human activity. Industry and technological control, agriculture and medicine, communications and scientific research - it is almost impossible to cover the entire range of applications of radioactive isotopes, although they all arose in just over 100 years.

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Isotopes are varieties of chemical elements in which the nuclei of atoms differ in the number of neutrons, but contain the same number of protons, and therefore occupy the same place in Mendeleev’s Periodic Table of Elements. There are stable (stable) and radioactive isotopes. The term "isotopes" was first proposed in 1910. Frederick Soddy (1877-1956), famous English radiochemist, Nobel Prize laureate in 1921, who experimentally proved the formation of radium from uranium.

Radioactive isotopes are widely used not only in nuclear energy, but also in a variety of instruments and equipment to determine the density, homogeneity of a substance, its hygroscopicity, etc. With the help of radioactive indicators, it is possible to monitor the movement of chemical compounds in physical, technological, biological and chemical processes, for which radioactive indicators (labeled atoms) of certain elements are introduced into the object under study and then their movement is observed. This method makes it possible to study reaction mechanisms during the transformation of substances under difficult conditions, for example at high temperatures, in a blast furnace or in the aggressive environment of a chemical reactor, as well as to study metabolic processes in living organisms. The oxygen isotope-18 helps to clarify the mechanism of respiration of living organisms.

The radioactive method of analyzing a substance makes it possible to determine the content of various metals in it, from calcium to zinc, in extremely small concentrations - up to 1 -10 g (only 10 -12 g of the substance is required). Radioactive drugs are widely used in medical practice to treat many diseases, including malignant tumors. Isotopes of plutonium-238 and curium-224 are used to produce low-power batteries for heart rhythm stabilizers. For their continuous operation for 10 years, only 150-200 mg of plutonium is enough (conventional batteries last up to four years).

As a result of radiation-chemical reactions, ozone is formed from oxygen, and hydrogen and complex compounds of low molecular weight olefins are formed from gaseous paraffins. Irradiation of polyethylene, polyvinyl chloride and other polymers leads to an increase in their heat resistance and strength. There are many examples of the practical application of isotopes and radioactive radiation. Despite this, people's attitudes towards radiation, especially in recent decades, have changed dramatically. Over about a hundred-year history, radioactive sources have come a long way from the elixir of life to a symbol of evil. Concepts of modern natural science: Textbook. manual for universities / A.A. Gorelov.- M.: VLADOS., 2000.- P. 285-288.

After the discovery of X-rays, many believed that radiation could cure all diseases and solve all problems. At that time, people did not want to see the dangers of radiation exposure. When Wilhelm Roentgen (1845-1923) discovered a new type of irradiation in 1895, a wave of delight swept the entire civilized world. The discovery not only shook the foundations of classical physics. It promised unlimited possibilities - in medicine they immediately began to use it for diagnosis, and a little later - for the treatment of a wide variety of diseases. X-ray diagnostics and radiotherapy have saved the lives of many people. Doctors, however, after some time began to limit the permissible number of x-rays for one patient, but no one seriously paid attention to the burns that occur after x-rays. The French physicist A. Becquerel, for example, had the habit of carrying a radium device in his trouser pocket. After some time, he noticed inflammation on his leg. To make sure that the device was the cause of the illness, he moved it to another pocket. But even the ulcer that appeared on the other leg could not sober up the scientist, who, like the rest, was euphoric from the new discovery. Radioactive radiation at that time was considered as a universal healing agent, the elixir of life. Radium proved effective in the treatment of benign tumors, and its “popularity” increased dramatically. Radium pillows, radioactive toothpaste and cosmetics appeared on the public market.

However, the first warning signs soon appeared. In 1911 It was discovered that Berlin doctors who dealt with radiation often developed leukemia. Later, the German physicist Max von Laue (1879-1960) experimentally proved that radioactive radiation adversely affects living organisms, and in 1925-1927. It became known that under the influence of radiation, changes in the hereditary substance - mutations - occur.

Complete sobering came after the atomic bombing of Hiroshima and Nagasaki. Almost all the survivors of the nuclear explosion were exposed to large doses of radiation and died of cancer, and their children inherited some genetic disorders caused by the radiation. This was first discussed openly in 1950, when the number of leukemia patients among victims of atomic explosions began to grow catastrophically. After the Chernobyl accident, mistrust of radiation grew into real nuclear hysteria.

Thus, if at the beginning of the 20th century. people stubbornly did not want to see the harm from radiation, then at the end of it they began to fear radiation even when it does not pose a real danger. The cause of both phenomena is the same - human ignorance. One can only hope that in the future a person will learn to adhere to the golden mean and turn knowledge about natural phenomena to his own benefit.

Use of radioactive isotopes as indicators (labeled atoms). Currently, in biology, biochemistry and physiology, radioactive isotopes are widely used as substances that allow research at the molecular level. They made it possible to study the movements of submicroscopically small bodies, as well as individual molecules, atoms, and ions among their own kind in the body, without disturbing its normal functioning. Several research methods have been proposed.

Radio indication method(labeled atom method) is based on the use of chemical compounds in the structure of which radioactive elements are included as a label. In biological research, radioactive isotopes of elements that make up the body and participate in its metabolism are usually used - 3 H, "C, 24 Na, 32 P, 35 S, 42 K, 45 Ca, 51 Cr, 59 Fe, 125 I, 131 I, etc. Radionuclides introduced into the body behave in biological systems in the same way as their stable isotopes.This circumstance makes it possible to trace the fate of not only radioactive isotopes, but also various labeled organic and inorganic compounds and control their transformation during the exchange process.

The great advantage of this method is its high sensitivity, which allows the use in research of negligible amounts (in weight terms) of the labeled compound, which cannot influence or change the normal course of life processes. Thus, if conventional analytical methods can determine isotopes weighing 10 -6 g, then modern radiometric instruments make it possible to measure radioactive isotopes whose mass is 10 -18 -10 -20 g. The use of the radioactive tracer method in the study of various biochemical and physiological processes has made it possible to describe them in the language of formulas and mathematical equations, i.e., move from a qualitative description of processes to their exact quantitative expression.

Control over the distribution and deposition of radionuclides in various organs can be carried out by external radiometry of experimental animals (for example, registration of 131 I gamma radiation in the thyroid gland) or accordingly prepared biomaterials (blood, organ tissue, urine, feces, etc.). The autoradiography method is widely used for these purposes.

Autoradiography is a method of obtaining photographic images as a result of the action of radiation from radioactive elements located in the object under study on a photographic emulsion. For the first time, autoradiography was used to study animal organisms by the Russian scientist E. S. London in 1904 r£J3a over the last three decades, thanks to the development and use of special nuclear emulsions, the autoradiography technique has been significantly improved and with its help great successes have been achieved in the study of metabolic processes, as well as in study of the distribution and localization of radioactive substances in the cells and tissues of animals and plants.

Autoradiography is divided into macroautoradiography and microautoradiography. Macroautoradiography (contact, contrast) gives a picture of the distribution of radioactive isotopes in the macrostructures of a biological object (quantitative assessment of the radioisotope concentration), from which one can judge the nature of the exchange and organotropy of the radionuclide. Microautoradiography (histoautoradiography) allows you to study the intracellular localization of a radioactive substance, as well as cellular structures and complex biochemical processes in them (synthesis of proteins, enzymes, etc.).

a) to the preliminary administration of a particular amount of a radioactive isotope to an experimental animal;

b) taking from him certain organs and preparations made from them (histosections, thin sections, blood, etc.) for autoradiography;

c) creating, for a certain time, close contact between the manufactured preparation containing a radioactive element and the photographic emulsion;

d) developing and fixing photographic material, as is done in ordinary photography.

Highly sensitive X-ray and photographic films are used as photographic material for macroradioautography; for historadiography, special liquid and removable nuclear emulsions (type “P”, “K”, “MR”, etc.) are used, which cover the histological preparations under study.

Autoradiographs are a cluster of black grains of reduced silver in a photographic emulsion, indicating the location of a radioactive substance in the material under study.

Macroradioautographs are analyzed visually, and when quantitatively assessed for radioactivity, densitometry of the optical density of blackening of the photoemulsion of radioautograms is carried out in comparison with the blackening density of the photoemulsion of a radiation source of known radioactivity.

Historadioautographs are studied under a microscope simultaneously with the histological specimen. When quantifying them, grains of reduced silver or tracks of alpha or beta particles in the emulsion are counted under high microscope magnification using an eyepiece micrometer with a grid.

A.D. Belov (1959) developed the “double radioautograph” technique, which, unlike existing methods, allows one to obtain separate radioautograms from two radioactive isotopes simultaneously located in the same object under study. This technique is based on taking into account the difference in radiation energy and the “lifetime” of isotopes. Thus, when studying phosphorus-calcium metabolism in bones using 32 P and 45 Ca, it is possible to obtain separate radioautographs for these isotopes when they are simultaneously administered to an experimental animal. Taking into account the relatively high radiation energy and the short half-life of 32 R, a 32 R autoradiograph is first obtained. To do this, a filter is placed between the object under study and the photographic emulsion, absorbing soft beta radiation of 45 Ca. The autoradiograph for 4b Ca is obtained after the decay of 32 R.

The “double radioautograph” technique allows not only to use experimental animals twice more economically, but also to obtain more reliable data, since it becomes possible to compare the accumulation and distribution of two labeled substances on the same animal and avoid difficulties that arise when comparing such indicators obtained from different animals. Using the “double autoradiography” technique, the dynamics of protein-mineral metabolism in the bone tissue of different animal species (dogs, sheep, pigs, calves) was studied normally, during healing of fractures and with various methods of osteosynthesis and stimulation of osteogenesis in comparison with the x-ray morphological picture and histochemical activity alkaline and acid phosphatases in bones. It was found that protein and phosphorus-calcium metabolism in normal bones and in fractures is directly dependent on each other and on the enzymatic activity of alkaline and acid phosphatases. The greatest intensity of protein and phosphorus-calcium metabolism occurs in those areas of the bone organ (periosteum, endosteum, bone marrow, the walls of the Haversian canals and the spongy part of the epiphyses, as well as callus tissues), where the enzymatic activity of phosphatases, growth, development and restructuring of bone tissue are more pronounced. fabrics.

With the help of gamma-emitting radioisotopes 24 Na, 131 1, 42 K and others introduced into the body, fundamentally new data on measuring blood flow speed, blood mass, the functional state of the thyroid gland and other organs and systems of animals were obtained through external intravital radiometry. These radioisotope studies have become firmly established in clinical practice.

For the intravital study of metabolism in various organs and tissues using 3-emitting isotopes with weak penetrating ability, A. D. Belov (1968) proposed a method of experimental research with the preliminary implantation of small-sized radiometric sensors of the SBI-9 type. Subsequently, this method was supplemented by the simultaneous implantation of temperature-recording sensors (microthermisters) for synchronous intravital study of metabolism and temperature reaction in conditions of chronic experience.The use of a radiothermometric research method made it possible to establish the rate of exchange and temperature reactions in the liver, bones, muscles and other organs, as well as to identify their correlative changes in normal conditions and in bone pathology in different species of animals. With the simultaneous study of various physical, chemical and physiological processes, those interrelations of phenomena are revealed, those correlative interactions of processes are discovered, the need for which I. P. Pavlov spoke about as a task of “synthetic physiology”. Consequently, the method of radioactive tracers has opened up immense prospects for intravital research of metabolism - a kind of vital biochemistry.

A very important achievement of modern biochemistry, obtained with the help of radioactive substances, can be considered the idea of ​​​​the constant dynamic state of metabolic processes in a living organism, the interconvertibility of many substances, the continuous decay and resynthesis, the continuous renewal of chemical compounds of living cells, which occurs even in a state of equilibrium of metabolic processes . Proteins, nucleoproteins, chromoproteins, fats, carbohydrates, mineral compounds are in a state of constant breakdown and synthesis. The nature of the exchange and its direction often depend on the predominance of the processes of synthesis or decay. Thus, when studying malignant tumors, it was found that their growth is not due to increased synthesis, but to a delay in the breakdown of tumor protein substances. Thanks to radioisotope tracers, it was possible to determine the rate of renewal of various components of tissues and organs. It has been proven that muscle proteins are replaced more slowly than others, and the liver, blood plasma, especially the intestinal mucosa, have a high renewal rate. Direct evidence of exchange between proteins in muscles, plasma, liver and other organs was also obtained.

In combination with other research methods, radioisotope methods played a huge role in the development of molecular biology and made it possible to come close to solving many important problems in biology. These include, in particular, the mechanisms of accumulation and use of energy in living organisms, pathways of protein biosynthesis, biological photosynthesis, muscle contraction, nervous excitation, reproduction and

heredity.

With the help of many chemical compounds labeled with radioactive isotopes (labeled amino acids, fatty and nucleic acids, glucose, phosphatides, mineral salts), it was possible to clarify such important issues as the influence of dietary substances on animal productivity, issues of intermediate metabolism and interconvertibility of compounds, and decomposition pathways and synthesis of chemical substances in a living animal body, determine the structure of chemical compounds, etc. The interconvertibility of palmitic and stearic acids has been proven, the conversion of ornithine into arginine, phenylalanine into tyrosine, the formation of creatine due to methyl groups synthesized from methionine or choline, the creation of glycine from arginine (during the breakdown of proteins and amidine), adrenaline from phenylalanine, the carbon chain of cystine from serine, the formation of liver phospholipids from blood plasma phosphates, etc. The radioindication method made it possible to clarify the features of the exchange and synthetic role of the microflora of the rumen and other parts of the gastrointestinal tract of ruminants, which could not be determined by other methods. Of great interest is the establishment of the possibility of synthesizing amino acids from ammonia, keto and hydroxy acids in the rumen of ruminants and supplying the body with such compounds, in particular the mammary gland, in connection with the formation of milk. Along with this, it was possible to study another interesting area of ​​​​metabolic processes in the animal body - the role of the digestive tract and digestive glands in the circulation of substances in the systems: blood - the walls of the digestive tract; digestive glands - the contents of the digestive canal. When determining absorption, the so-called digestibility, ways were found to eliminate errors introduced by endogenous factors - constant mixing of substances secreted by the digestive glands and bile into the intestinal contents.

The study of metabolism in the body by using the radioisotope indication method confirmed the position of the reversibility of many intermediate metabolic processes, the possible variability of intermediate metabolic pathways under different biological conditions of the body and when environmental conditions change. The lability of internal environments and metabolic processes serves as the basis for the body’s adaptation to a changing external environment. Radioisotope tracers make it possible to detect adaptive changes in metabolism in an animal organism and open up new prospects in this regard.

Radioactive isotopes made it possible to study the metabolism of macro- and microelements without introducing excess substances into the diet, without disturbing the natural content of the studied substances in the body. As a result, it was possible to reliably establish the rate of accumulation of minerals in various organs and tissues and their removal from the body, as well as to study the chemical compounds in which the element is fixed during the process of its transfer or localization. Another important result of the use of radioactive isotopes in the study of mineral metabolism is the establishment of the rate of renewal of the mineral composition of organs and some bone tissue compounds. To date, much data has been obtained on the exchange and accumulation in tissues of radioactive isotopes of elements such as calcium, phosphorus, cobalt, copper, zinc, manganese, beryllium, barium, strontium, iodine, etc. The overall result of these studies confirms that penetration into individual tissue of mineral substances, for example, trace elements, is controlled not simply by the laws of diffusion, but primarily by cellular metabolism associated with specific chemical processes in the cell, depending on the action of enzymes.

The method of radioisotope indication in the study of the metabolism of mineral substances made it possible to penetrate into the processes of intermediate metabolism occurring with the participation of mineral substances, including trace elements (131 I, 60 Co, 64 Cu, etc.).

Since the introduction of the electrophoretic method into biology and medicine for the separation of human and animal serum proteins, a lot of data have accumulated indicating a nonspecific reaction in shifts in the protein formula under various conditions of the body. However, certain quantitative changes in serum proteins are interpreted differently by different authors. This is due to the fact that one method of electrophoretic separation of proteins allows us to establish only quantitative shifts in the protein formula, but it is not able to reveal the intimate aspects of the dynamics of protein metabolism, the role and significance of various protein fractions, the intensity of their synthesis and breakdown in a particular disease. With the help of radioactive isotopes, it became possible to trace these processes. For this purpose, A.D. Belov (1972) proposed a method for quantitative autoradiography of blood serum proteins subjected to electrophoresis (autoradioelectrophoresis method), as well as the principle of mathematical processing of radioautograms to determine the rate of biosynthesis and breakdown of proteins and their functional ability. To determine protein synthesis, labeled amino acids (35 S-methionine, 14 C-glycine, etc.) are used, and functional capacity - 32 P, 45 Ca, etc. This technique allowed the author to obtain not only a visual document (radioautogram) characterizing the intensity of inclusion of labeled substances in one or another protein fraction, but also to quantify the biosynthesis, breakdown and functional ability of each protein fraction using indicators of relative specific activity, to decipher the intimate aspects of the mechanism of quantitative shifts in the protein formula of blood serum in animals under normal conditions and with bone pathology.

Using 51 Cr included in the hemoglobin molecule and 75 Se in the composition of methionine, the lifespan of erythrocytes in the peripheral blood of various farm animals was determined.

The radioactive isotope 32 P was used to identify the rate of sperm maturation, the timing of their movement through the reproductive tract of males, and changes in these timing under different sexual loads.

In the last decade, methods of in vitro radioisotope research, in which radioactive substances are not introduced into the body, have undergone rapid development. This circumstance has significantly expanded the possibility of using the radioindication method in laboratory and clinical practice. In vitro methods are widely used in endocrinology and immunology. Promising developments are underway for their use in the study of other systems. When studying hormonal status in humans and animals, a radioimmune (radiocompetitive) method is used, based on the ability of an unlabeled hormone in the blood serum sample being studied to compete with the labeled hormone for antibodies and thereby block the binding of the labeled hormone. Ultimately, the percentage of binding of the total labeled antigen to antibodies is determined, which is inversely proportional to the amount of unlabeled antigen, i.e., the amount of hormone in the test sample. The method is characterized by high specificity and sensitivity. Currently, insulin, growth hormone, ACTH, peptide and many other hormones are determined in this way. In recent years, tests of standard kits (whales) specially prepared for the determination of hormones have been widely used in in vitro diagnostics.

E. A. Nezhikova (1979) was the first to use a radioimmunological method to trace the dynamics of pituitary gonadotropic hormones - luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the blood serum of cows by month of pregnancy and seasons of the year. The influence of these hormones not only on the physiological state of animals, but also on productivity has been revealed. Thus, if in cows with average productivity in the autumn the amount of LH in the first month of pregnancy reaches 32.1 ng/ml, then in highly productive ones it is 24.77 ng/ml. The same pattern can be observed in other periods of pregnancy. At the same time, there is a clear dependence of the LH level on the month of pregnancy and the season of the year. Thus, in cows in the third month of pregnancy in the spring, the LH level is 4.33 ng/ml, in the summer - 30.9 ng/ml, in the autumn - 34.8 ng/ml and in the winter - 63.2 ng/ml.

The radioisotope method for studying the functional state of the thyroid gland in animals during clinical examination deserves serious attention, as well as for determining the dose of potassium iodide supplements in areas of iodine deficiency, preventing metabolic disorders and increasing productivity. With iodine deficiency, an anovulatory cycle is observed in cows, in pigs - the birth of dead, hairless or low-viable piglets, in chickens - a sharp decrease in egg production. For the practice of animal husbandry and veterinary medicine, the greatest interest is in vitro methods of radioisotope studies based on determining the inclusion of triiodothyronine labeled with 125 I or 131 I in erythrocytes, or by the degree of binding of thyroxine labeled with radioiodine to protein fractions of blood serum. These methods make it possible to indirectly determine the amount of hormone secreted by the thyroid gland and thereby judge its functional activity.

V.P. Ostapchuk, A.D. Belov and N.A. Kovalev (1979) developed a radioimmune method for diagnosing rabies, which is based on the binding of radionuclide-labeled specific antibodies with rabies antigen in brain smears of sick animals and measuring the radioactivity of the resulting complex. The advantage of this method in comparison with traditional pathomorphological ones is its high specificity, sensitivity, speed of execution and the ability to study stale, already decomposed pathological material, as well as quantitative expression of the research results.

All of the above radioimmunological and radioisotope research methods are available for wide laboratory practice in regional radiological departments and republican radiological veterinary laboratories.

Neutron activation analysis is a promising highly sensitive method for determining ultramicroquantities of stable isotopes in various biological materials (blood, lymph, tissues of various organs, etc.). It consists in the fact that the material under study is exposed to a neutron flux under the conditions of a nuclear reactor. As a result, radioactive products (activation products) are formed, which are then subjected to radiochemical analysis and radiometry.

A wide variety of questions in biology, physiology, dynamic biochemistry and ecology of microorganisms can be solved by the method of radioactive tracers. The incorporation of labeled compounds into the microbial cell occurs as a result of their active involvement in metabolism during the cultivation of microbes in a nutrient medium containing radionuclides. Microbes can even be marked with a double label, for example 32 P and 35 S. They absorb radionuclides and, when multiplying, pass them on to their offspring. A labeled pathogenic culture is administered to animals, which are killed at certain time intervals, and the speed and routes of spread of microbes in the body are radiometrically determined by the specific activity of its organs. In this way, it is possible to trace the fate of pathogenic microbes and vaccines in the body of experimental animals.

Viruses can also be marked by introducing solutions of radioactive isotopes 32 P, 35 5-methionine, 35 5-cystine, 14 C-glycine, etc. into tissue cultures and other nutrient media. The radioactive label is actively incorporated into the components of the virus during its reproduction. It should be noted that 32 P is included in the RNA and phospholipids of the virus, and labeled amino acids are included in its protein shell.

The method of radioactive tracers has found application in entomology in studying the routes and speed of migration, places of reservation of flies, mosquitoes, ticks and other insects that carry pathogenic microorganisms and the effectiveness of measures taken to combat them, as well as for tracking the transition of insecticides to insects. Organisms are marked by introducing a radioisotope into food, or by growing them in appropriate media containing radioisotopes. The choice of radioactive tracer depends on the research task.

The use of radioactive isotopes for the diagnosis and treatment of animals. Currently, radioactive isotopes are widely used in medicine for cardiovascular diseases, malignant neoplasms, blood diseases (myeloid leukemia, lymphocytic leukemia, polycythomia, etc.), peripheral nervous system (neuritis, radiculitis), skin (eczema, dermatitis, boils), thyroid glands (thyrotoxicosis), as well as to suppress transplantation immunity during organ transplantation, etc.

In diseases of the cardiovascular system, the speed of blood flow changes dramatically. To determine it, 24 Na, 131 I, 42 K, 32 R are used. In healthy people at rest, the blood flow speed is 5-6 s in the small circle, 12-16 s in the large circle. The therapeutic use of radioisotopes and radiation for tumors is based on their biological effect. Young, vigorously reproducing cells are most affected by radiotherapy. This circumstance made it possible to develop radiotherapy for patients with malignant and benign tumors and diseases of the hematopoietic organs. Depending on the location of the tumor, external gamma irradiation is carried out using gamma therapeutic units. Apply applications to the skin for contact action; colloidal solutions of radioactive drugs are injected into the thickness of the tumor directly or in the form of hollow needles filled with radioisotopes; short-lived radionuclides are injected intravenously, selectively accumulating in tumor tissues and critical organs.

A.D. Belov (1968) created an eye applicator and developed a method for its use in eye diseases in animals. Using an applicator charged with 32 P and 89 Sr, positive results were obtained for ulcerative and infectious conjunctivoceratitis, vascularization of the cornea in calves and dogs. A single dose was 50-100 R, for a full course of treatment - 200-2000 R. The author successfully used small doses of phosphorus-32 (0.01 μCi/kg of animal weight) to accelerate the regeneration of bone tissue and normalize mineral metabolism in animals with bone fractures by injecting a radioactive solution into the fracture area.

The stimulating effect of X-ray and gamma irradiation can be used to increase the economically useful qualities of chickens (egg production, vitality and growth of chickens).

The radioindication method provides an invaluable service in studying the pharmacodynamics of drugs, the speed and routes of their penetration and excretion from the body under normal conditions and in various pathological conditions. Valuable data have been obtained from testing potent drugs, as well as drugs that were previously considered harmless.

Sterilization using ionizing radiation. They are used for cold sterilization of biological preparations (vaccines, serums, vitamins, nutrient media, etc.), surgical sutures and dressings that cannot withstand temperature treatment.

Non-thermal processing methods are used in the food industry for food preservation. Good results are obtained with gamma irradiation with a dose of 1.8 million rubles.

Sterilization is of great importance for the disinfection of manure at large livestock complexes, at enterprises for processing leather and fur raw materials, wool, bristles, feathers and down. Radiation sterilization is used in the fight against harmful insects (barn mites, stinging flies, etc.).

The above, of course, far from exhausts the variety of areas of application of radioactive isotopes and ionizing radiation in biology, veterinary medicine and animal husbandry. However, from the above examples it is clear that radioactive isotopes and ionizing radiation, being fundamentally new in the study of nature, open up great opportunities in the study of life processes, the pathogenesis of diseases, the diagnosis and therapy of farm animals, as well as in solving other important economic problems.