The frequency of ultrasonic waves is as high as 20,000 Hz or more (more than 20,000 vibrations per second). Because of its high frequency, it has the following characteristics: (a) good directivity and almost linear propagation; (b) Strong penetration ability, which can penetrate many substances that cannot be penetrated by electromagnetic waves; (c) When propagating in the medium, it can generate great force, which can be used for cutting and drilling hard materials, and can also be used for cleaning and disinfection. We are familiar with the application of ultrasound, which is commonly used in hospitals. It emits ultrasonic waves into the human body, and judges whether there are abnormalities according to the changes of the transmission and reflection ability of human tissues to ultrasonic waves, such as pathological examination of human organs and calculus examination. It has the advantages of no harm to human body, simplicity and quickness.
Infrasound, also known as infrasound, is a low-frequency wave with a frequency below 20Hz. Many natural disasters, such as earthquakes, volcanic eruptions and tornadoes. And emits infrasound before infrasound occurs. Infrasound waves can cause harm to human body, causing symptoms such as headache, vomiting and dyspnea. In 1930s, an American physicist did an experiment: he brought an infrasound generator into the theater, turned it on quietly after the performance, and then sat in his box to observe the movement. I saw the audience sitting around the infrasound wave have a panic and puzzled expression, which quickly spread to the whole theater. Infrasound waves have the characteristics of wide source, long propagation and strong penetration. Scientists use it to predict typhoons and study the atmospheric structure. Militarily, infrasound waves can be used to detect nuclear explosions in the atmosphere, track missiles and so on.
1890, a sailboat named "Marpolo" suddenly disappeared mysteriously on the way from New Zealand to England. Twenty years later, it was found off the coast of Tierra del Fuego. Strangely, all the sails on the ship are intact. The handwriting in the captain's diary is still legible. Even those crew members who have been dead for many years are "in their positions" and maintain the "posture" when they were on the job;
At the beginning of 1948, a Dutch cargo ship passed through the Straits of Malacca and was caught in a storm. All the sailors died inexplicably. At the entrance to the Boradeli Cave in Hungary, three tourists suddenly fell to the ground and stopped breathing. ......
The above tragedy has aroused widespread concern among scientists, and many scientists have also conducted long-term research on the cause of death of crew members. As for the tragedy at the beginning of this article, how did the crew die? Did you die of skyfire or lightning? No, because there are no signs of burning on the ship; Did you die by the pirate's sword? Don't! The remains of the victims showed signs of fighting before their death; Did you die of hunger and thirst? Not really! There was enough food and fresh water on board. As for the second and third tragedies mentioned above, is it suicide or homicide? What was the cause of death? Who is the murderer? The test results showed that no scars were found on all the victims and there were no signs of poisoning. Obviously, the theory of murder or suicide is no longer valid. So, did the sudden attack of cardiovascular and cerebrovascular diseases such as He Yi kill them? The autopsy report of the forensic doctor shows that the deceased were all strong before his death!
After repeated investigations, it was finally found that the "murderer" who caused the above tragedy was a kind of infrasound that people didn't know much about. Infrasound is a kind of sound wave that vibrates very little every second and can't be heard by human ears. The frequency of infrasound is very low, generally below 20 MHz, but the wavelength is very long and the propagation distance is very long. It travels farther than ordinary sound waves, light waves and radio waves. Such as frequency below 6544. Can spread to thousands or even tens of thousands of kilometers away. 1960, a major earthquake occurred in Chile, South America, and infrasound waves generated during the earthquake spread to all corners of the world! 196 1 year, the Soviet union conducted a nuclear explosion in the arctic circle, and the infrasound waves produced actually turned around the earth for five times before disappearing!
Infrasound waves have strong penetrating power, which can not only penetrate the atmosphere, seawater and soil, but also penetrate solid reinforced concrete buildings, even tanks, warships, submarines and airplanes. Infrasound can not only cause dizziness, irritability, tinnitus, nausea, palpitation, blurred vision, dysphagia, stomachache, liver dysfunction, numbness of limbs, but also damage the brain and nervous system.
Why can infrasound cause death?
It turns out that the natural vibration frequency of human internal organs is similar to infrasound frequency (0.0 1 ~ 20 Hz). If the external infrasound frequency is close to or the same as the vibration frequency of internal organs, it will cause "* * * vibration" of human internal organs, thus causing a series of symptoms such as dizziness, irritability, tinnitus and nausea. It is mentioned above, especially when the natural vibration frequency of human abdominal cavity and chest cavity is close to the external infrasound. It is more likely to cause * * * vibration of human internal organs, resulting in damage to human internal organs and death. The tragedy that happened in the Straits of Malacca mentioned at the beginning is because the cargo ship happened to encounter a storm at sea when approaching the Straits. The storm rubs against the waves, producing infrasound waves. Infrasound waves make people's heart and other internal organs vibrate and beat violently, leading to blood vessel rupture and eventually death.
Although infrasound is invisible, it is always produced, threatening the safety of human beings. In nature, such as solar magnetic storm, strait roar, thunder and lightning, sudden change of air pressure; In the factory, mechanical shock and friction; Military atomic bomb, hydrogen bomb explosion test, etc. Can produce infrasound waves.
Due to the strong penetration of infrasound, the International Maritime Rescue Organization has set up "infrasound positioning stations" on some islands far from the mainland to monitor the tidal ocean surface. Once a ship or plane is wrecked and attached to the sea, its position can be quickly determined and rescue can be carried out.
In recent years, some countries have devoted themselves to the development of infrasonic weapons-infrasonic bombs, which are still in the development stage, but scientists predict that; As long as the infrasonic bomb explodes, in an instant, everyone on the ground in Fiona Fang for more than ten kilometers will be killed, and no one will be spared. Infrasound weapons can penetrate 15 cm of concrete and tank steel plates. Even if people hide in bomb shelters or get into the "belly" of tanks, they are still doomed to be disabled. Infrasound bombs, like neutron bombs, only kill creatures and do not destroy buildings. But compared with the two,
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Ultrasonic wave:
Ultrasound therapeutics is an important part of ultrasound medicine. Ultrasonic energy is applied to the diseased part of human body during ultrasonic treatment, so as to achieve the purpose of treating diseases and promoting physical rehabilitation.
In the world, ultrasound is widely used in diagnostics, therapeutics, engineering, biology and other fields. Saifurui's home ultrasonic therapy machine belongs to the application category of ultrasonic therapy.
(1) engineering applications: underwater positioning and communication, underground resource exploration, etc.
(2) Biological applications: shearing macromolecules, bioengineering and seed treatment.
(3) Diagnostic applications: type A, type B, type M, type D, dual-function and color ultrasound.
(4) Therapeutic application: physiotherapy, cancer treatment, surgery, extracorporeal lithotripsy, dentistry, etc.
Characteristics of ultrasonic wave:
1. When ultrasonic wave propagates, it has strong directivity and easy energy concentration.
2. Ultrasonic waves can propagate in different media and far enough.
3. The interaction between ultrasonic wave and sound transmission medium is moderate, and it is easy to carry the information of sound transmission medium state (diagnosis or function of sound transmission medium). (treatment)
Ultrasonic wave is a waveform, which can be used as a carrier or medium for detecting and loading information (such as B-ultrasound for diagnosis); At the same time, ultrasound is a form of energy. When its intensity exceeds a certain value, it can affect, change or even destroy the state, nature and structure of the medium that propagates ultrasonic waves (used for treatment).
The development history of ultrasound;
First, internationally:
/kloc-from the end of 0/9 to the beginning of the 20th century, after the piezoelectric effect and anti-piezoelectric effect in physics were discovered, people solved the method of using electronic technology to generate ultrasonic waves, which quickly opened a historical chapter in the development and popularization of ultrasonic technology.
1922, the first invention patent of ultrasonic therapy appeared in Germany.
1939 published a literature report on the clinical effect of ultrasonic therapy.
In the late 1940s, ultrasonic therapy rose in Europe and America. It was not until the first international conference on medical ultrasound held in 1949 that papers on ultrasound therapy were exchanged, which laid the foundation for the development of ultrasound therapy. 1956 many papers were published in the second international congress of ultrasound medicine, and ultrasound therapy has entered a practical and mature stage.
Second, the domestic side:
In China, the field of ultrasound therapy started late, and only a few hospitals carried out ultrasound therapy in the early 1950s. From 65438 to 0950, the ultrasonic therapeutic machine with the frequency of 800KHz was first used in Beijing to treat various diseases, and it was gradually popularized in the 1950s, with domestic instruments. The published literature report began at 1957. In the 1970s, various types of ultrasonic therapeutic instruments appeared in China, and ultrasonic therapy was popularized in major hospitals all over the country.
Over the past 40 years, major hospitals in China have accumulated a considerable amount of information and rich clinical experience. Especially in the early 1980s, ultrasonic extracorporeal mechanical wave lithotripsy (ESWL) and ultrasonic surgery appeared, which was a major breakthrough in the treatment history of lithiasis. Now it has been popularized and applied internationally. High intensity focused ultrasound noninvasive surgery makes ultrasound therapy occupy an important position in contemporary medical technology. In 2 1 century (HIFU), focused ultrasound surgery is regarded as the latest technology for treating tumors in 2 1 century.
Mechanism of ultrasonic treatment;
1. Mechanical effect: the effect produced when ultrasonic waves advance in a medium. (The propagation of ultrasonic wave in medium is a mechanical effect produced by reflection) It can cause some reactions in the body. Ultrasonic vibration can cause the movement of substances in tissues and cells. Due to the fine massage of ultrasonic waves, the cytoplasm flows, and the cells vibrate, rotate and rub, thus producing the effect of cell massage, also known as "internal massage". This is the unique feature of ultrasonic therapy, which can change the permeability of cell membrane, stimulate the diffusion process of cell semipermeable membrane, promote metabolism, accelerate blood and lymphatic circulation, improve cell ischemia and hypoxia, improve tissue nutrition, change protein synthesis rate and improve regeneration function. Changing the internal structure of cells leads to changes in the function of cells and softens the extension of hard connective tissue.
The mechanical action of ultrasound can soften tissues, enhance infiltration, improve metabolism, promote blood circulation and stimulate nervous system and cell function, so it has unique therapeutic significance.
2. Warm effect: human tissues have a relatively large absorption capacity of ultrasonic energy, so when ultrasonic waves propagate in human tissues, their energy is continuously absorbed by the tissues and becomes heat, resulting in the temperature of the tissues themselves rising.
The process of heat production is not only an energy conversion process in which mechanical energy is converted into heat energy in a medium. Namely endogenous heat. Ultrasonic hyperthermia can increase blood circulation, accelerate metabolism, improve local tissue nutrition and enhance enzyme activity. Generally speaking, the thermal effect of ultrasound is significant in bones and connective tissues, while fat and blood are the least.
3. Physical and chemical effects: Both mechanical effects and thermal effects of ultrasound will cause some physical and chemical changes. Practice has proved that some physical and chemical effects are often the secondary effects of the above effects. TS-C therapeutic instrument has the following five functions through physical and chemical actions:
A dispersion: ultrasound can improve the permeability of biofilm, and the permeability of cell membrane to potassium and calcium ions changes strongly after ultrasound. Thereby enhancing the diffusion process of biofilm, promoting material exchange, accelerating metabolism and improving tissue nutrition.
B. Thixotropic effect: under the action of ultrasonic wave, gel can be transformed into sol state. Softening effect on muscles and tendons, and some pathological changes related to tissue water shortage. Such as rheumatoid arthritis and degenerative diseases of joints, tendons and ligaments.
C. Cavitation: Cavitation forms, or keeps steady unidirectional vibration, or expands and collapses, changes cell function, and increases intracellular calcium level. Fibroblasts were activated, protein synthesis increased, vascular permeability increased, angiogenesis accelerated, and collagen tension increased.
D. Polymerization and depolymerization: Polymerization of water molecules is the process of synthesizing multiple identical or similar molecules into a larger molecule. The depolymerization of macromolecules is a process in which macromolecules become small molecules. It can increase the activity of hydrolase and collagenase in joints.
E. Anti-inflammatory repair of cells and molecules: Under the action of ultrasound, the PH value of tissues can develop to alkalinity. Relieve local acidosis related to inflammation. Ultrasound can affect blood flow, produce inflammation, inhibit and play an anti-inflammatory role. Make white blood cells move and promote angiogenesis. Collagen synthesis and maturation. Promote or inhibit the repair and healing process of injury. So as to achieve the process of cleaning, activating and repairing damaged cells and tissues.
Infrasound:
Because the frequency of infrasound is very low and the absorption coefficient of infrasound in the atmosphere is very small, it has strong penetration and can spread to very far places with little energy attenuation. Infrasound waves below 10Hz can travel to a distance of several Qian Qian meters. 1983 In the summer, Krakato volcano erupted between Sumatra and Java in Indonesia. It took 108 hours for the intense infrasound generated during the volcanic eruption to go around the earth three times. Micro-barometers all over the world have recorded its vibration aftermath. 19861On October 29th, the American space shuttle Challenger exploded. The infrasound produced by the explosion lasted for 12 hours and 53 minutes, and its explosive power was so strong that even the monitor of the monitoring station of the Institute of Acoustics, Xiangshan, Beijing, which was more than 10000 kilometers away, "heard". The usual sound insulation and absorption methods have little effect on the super penetration of infrasound. 7000 Hz sound waves can be blocked by a piece of paper, while 7Hz infrasound waves can't be stopped by thick walls. Infrasound waves can penetrate more than ten meters of reinforced concrete.
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