Ultrasonic frequency is as high as 20,000Hz or more (more than 20,000 vibrations per second), because of its high frequency, so it has the following characteristics: (a) good directionality, almost along the straight line propagation; (b) strong penetrating ability to penetrate many electromagnetic waves can not penetrate the material; (c) propagation in the medium to produce a great force! For the application of ultrasound, we are more familiar with the hospital is commonly used ultrasound, it is the ultrasound into the human body, according to the human body tissue to the ultrasound conduction and reflection ability of the changes to determine the presence of abnormalities, such as the human body organs to do lesions, stone inspection, etc., it has the human body without damage, simple and rapid The advantages of this procedure are that it is non-invasive, simple and rapid.
The infrasound, also known as subsound, is a low-frequency wave with a frequency of less than 20Hz. Many natural disasters such as earthquakes, volcanic eruptions, tornadoes, etc. will be issued before the occurrence of infrasound. Infrasound can cause harm to the human body, causing headaches, vomiting, breathing difficulties and other symptoms. In the 1930s, a physicist in the United States has done experiments: he brought an infrasound generator into the theater, the opening quietly open, and then sat in his box to observe the movement, only to see the audience sitting around the infrasound device to produce a kind of panic and confusion, and soon spread to the entire theater. Infrasound is characterized by a wide range of sources, spread far, penetrating scientists use it to predict typhoons, research atmospheric structure. In the military can use infrasound to detect nuclear explosions in the atmosphere, tracking missiles and so on.
In 1890, a sailing ship named "Marlborough" sailed from New Zealand to England, suddenly and mysteriously disappeared. Twenty years later, it was found off the coast of Tierra del Fuego. The strange thing is: the ship's cargo is intact. It's as good as new. The captain's diary writing is still vaguely recognizable; even those who have been dead for many years of the crew, but also "each in its place", to maintain the year in the post when the "posture";
In early 1948, a Dutch freighter in the Strait of Malacca, when the ship was passing through. After a storm, the whole ship seafarers inexplicably died; in Hungary, the entrance to the Bora Deli caves, three travelers suddenly fell to the ground in unison, stopped breathing ......
The above tragedies have attracted widespread attention from scientists, many of whom have also carried out long-term research into the causes of the crew's death． Take the tragedy at the beginning of this article, how did the crew die? Was it killed by fire or lightning? No, because the ship did not have the slightest trace of burning; is the death of the pirates under the knife? No! Were they killed by pirates' knives? No! The remains of the victims showed signs of a struggle before death; were they killed by hunger and thirst? No! There was enough food and fresh water stored on board. As for the second and third tragedies mentioned earlier, were they suicides or homicides? What was the cause of death? Who was the murderer? The results of the tests were: no injuries were found on any of the victims, and there were no signs of poisoning. Obviously, the murder or suicide theory is no longer valid. Then, is it as well as the disease of a kind of cardiovascular disease of sudden onset of death? Forensic autopsy report shows that the deceased were all very healthy!
After repeated investigations, finally figured out the "murderer" of the above tragedy, is a kind of infrasound sound waves for people do not know very well. Infrasound is a few vibrations per second, the human ear can not hear the sound waves. Infrasound sound wave frequency is very low, generally below 20 MHz, but the wavelength is very long, the propagation distance is also very far. It is more than the general sound waves, light waves and radio waves are far. For example, the frequency of less than 1 Hz infrasound, can be transmitted to thousands to tens of thousands of kilometers away from the place. 1960, South America's Chilean earthquake, the earthquake produced infrasound spread all over the world every corner! 1961, the Soviet Union in the Arctic Circle carried out a nuclear explosion, resulting in infrasound was around the Earth after 5 circles before disappearing!
Infrasound has a strong penetrating power, not only can penetrate the atmosphere, seawater, soil, and can also penetrate the solid steel and concrete buildings, and even tanks, warships, submarines and airplanes are not under. Infrasound penetrates the human body, not only can make people produce dizziness, irritability, tinnitus, nausea, palpitations, blurred vision, swallowing difficulties, stomach pain, liver dysfunction, numbness of the limbs, but also may destroy the brain nervous system, resulting in significant damage to brain tissue. Infrasound has the most serious effect on the heart and can eventually lead to death.
Why can infrasound kill people?
Originally, the body's internal organs and the inherent frequency of vibration and infrasound frequency similar (0.01 ~ 20 H), if the external frequency of infrasound and the body's visceral vibration frequency is similar to or the same, will cause the human viscera of the "*** vibration", which makes people produce the above mentioned dizziness, irritability, tinnitus, nausea and so on. A series of symptoms. Especially when the human abdominal cavity, chest cavity and other intrinsic vibration frequency and foreign infrasound frequency consistent, more likely to cause human visceral *** vibration, so that the human body visceral damage and death. Earlier mentioned at the beginning of the tragedy occurred in the Strait of Malacca, is because the cargo ship approaching the strait, just met on the sea up a storm. The storm rubbed against the waves, creating infrasound. Infrasound makes the human heart and other internal organs shaking, beating wildly, so that blood vessels rupture, and finally contribute to death.
While infrasound is invisible, it is always generated and threatens the safety of human beings. In the natural world, such as solar magnetic storms, Channel roar, thunder and lightning, sudden changes in air pressure; in factories, mechanical impact, friction; military atomic bomb, hydrogen bomb explosion test, etc., can produce infrasound.
Because infrasound has a strong penetrating power, therefore, the International Maritime Rescue Organization in a number of islands far from the mainland to establish the "infrasound positioning station", monitoring the tide of the ocean surface. Once the ship or aircraft wrecked with the sea, you can quickly determine the location, rescue.
In recent years, some countries use infrasound can "kill" this feature, infrasound weapons - infrasound bombs are committed to the development of although currently still in the development stage, but scientists predict; as long as the infrasound bombs a bang, in an instant, in a circle of more than ten kilometers on the ground. A dozen kilometers around the ground, all people will be killed, and no one can be spared. Infrasound weapons can penetrate 15 centimeters of concrete and tank steel. Even if a person hides in a bomb shelter or drills into the tank's "belly", he or she will still be crippled. Infrasonic bombs, like neutron bombs, only kill and maim living creatures and do no damage to buildings. But compared to the two, the infrasound bomb is far more lethal than the neutron bomb.
<Role>:
Ultrasonic:
Ultrasonic therapeutics is an important part of ultrasound medicine. Ultrasound therapy when the ultrasound energy on the human body lesions, in order to achieve the purpose of treatment of diseases and promote the recovery of the body.
In the world, ultrasound is widely used in diagnostics, therapeutics, engineering, biology and other fields. Safari home ultrasound therapy machine belongs to the use of ultrasound therapeutics.
(A) engineering applications: underwater positioning and communications, underground resource exploration, etc.
(B) biological applications: shear macromolecules, bioengineering and treatment of seeds, etc.
(C) diagnostic applications: A-type, B-type, M-type, D-type, dual-performance and color ultrasound, etc.
(D) therapeutic applications: physical therapy, cancer treatment, surgery, body lithotripsy, ultrasound, ultrasound, ultrasound, ultrasound, ultrasound, ultrasound, ultrasound, and so on.
Features of ultrasound:
1. Ultrasound wave propagates in a strong direction, and the energy is easy to concentrate.
2, ultrasonic waves can be propagated in a variety of different media, and can be propagated far enough distance.
3, the interaction between ultrasound and sound transmission medium is moderate, easy to carry information about the state of the sound transmission medium (diagnosis or effect on the sound transmission medium. (Treatment)
Ultrasonic wave is a form of fluctuation, it can be used as a carrier or medium for detecting and loading information (such as B ultrasound used as a diagnostic); ultrasound at the same time is a form of energy, when its intensity exceeds a certain value, it can be through the interaction of the medium with the propagation of ultrasonic waves, to affect, change or destroy the latter's state, nature and structure (used as a therapeutic).
History of the development of ultrasound:
I. International:
Since the end of the 19th century to the beginning of the 20th century, the discovery of the piezoelectric effect and the anti-piezoelectric effect in physics, after the discovery of the piezoelectric effect, people solved the use of electronics to produce ultrasound, and since then quickly opened the development and popularization of ultrasound technology of the history of the chapter.
In 1922, Germany appeared the first ultrasound therapy invention patent.
In 1939, the literature published on the clinical effects of ultrasound treatment.
The late 40's ultrasound therapy in Europe and the United States, until the first international medical ultrasound conference held in 1949, there is ultrasound therapy paper exchanges for the development of ultrasound therapy laid the foundation for the second international ultrasound conference in 1956, there have been a number of papers published, ultrasound therapy has entered the practical stage of maturity.
Second, the domestic side:
Domestic in the field of ultrasound therapy started a little late in the early 1950s, only a few hospitals to carry out ultrasound therapy, from 1950, first began to use 800KHz frequency ultrasound therapy in Beijing to treat a variety of diseases, to the 50's began to gradually promote, and have a domestic instrument. Public literature reports were first published in 1957. By the 1970s, there were various types of domestic ultrasound therapeutic instrument, ultrasound therapy popularized in large hospitals across the country.
Over the past 40 years, the country's major hospitals have accumulated a considerable amount of information and relatively rich clinical experience. In particular, the emergence of ultrasound extracorporeal mechanical wave lithotripsy and ultrasound surgery in the early 1980s was a major breakthrough in the history of stone disease treatment. Nowadays, it has been popularized and applied internationally. High-intensity focused ultrasound noninvasive surgery has made ultrasound therapy occupy an important position in contemporary medical technology. And in the 21st century (HIFU) ultrasound focused surgery has been hailed as the latest technology for the treatment of tumors in the 21st century.
Mechanism of ultrasound treatment:
1. Mechanical effect: the effect of ultrasound in the medium forward. (Ultrasound propagation in the medium is produced by reflection and mechanical effects) it can cause a number of body reactions. Ultrasound vibration can be caused by the movement of substances within the tissue cells, due to the ultrasound micro-massage, so that the cell plasma flow, cell shock, rotation, friction, thus producing the role of cell massage, also known as the "internal massage" This is the unique characteristics of ultrasound therapy can change the permeability of the cell membrane, stimulate the diffusion of cellular semi-permeable membrane process, promote the metabolism, accelerate blood and lymphatic flow, and promote the development of the body. Metabolism, accelerate blood and lymph circulation, improve cell ischemia and hypoxia, improve tissue nutrition, change the rate of protein synthesis, improve regeneration function. Make changes in the internal structure of the cell, resulting in functional changes in the cell, so that the hard connective tissue extension, flaccid.
The mechanical action of ultrasound can soften tissues, enhance penetration, improve metabolism, promote blood circulation, stimulate the nervous system and cellular functions, thus having the unique therapeutic significance of ultrasound.
2. Thermal effect: the human body tissue has a relatively large absorption capacity of ultrasound energy, so when the ultrasound in the human body tissue propagation process, its energy is constantly absorbed by the tissue into the heat, the result is that the organization's own temperature rise.
Heat generation process is both mechanical energy in the medium into heat energy conversion process. That is, endogenous heat. Ultrasound warming effect can increase blood circulation, accelerate metabolism, improve local tissue nutrition, enhance enzyme activity. In general, the thermal effect of ultrasound to bone and connective tissue is significant, fat and blood for the least.
3. Physical and chemical effects: the mechanical and thermal effects of ultrasound can promote a number of physical and chemical changes. It has been proved that some physical and chemical effects are often the secondary effects of the above effects. TS-C-type therapy machine through the physical and chemical effects of the following five secondary effects:
A. Dispersive effect: ultrasound can improve the permeability of biological membranes, ultrasound, the cell membrane of potassium, calcium ions after the effect of strong changes in permeability. Thus, it enhances the diffusion process of biofilm, promotes material exchange, accelerates metabolism, and improves tissue nutrition.
B. Thixotropic effect: Under the action of ultrasound, the gel can be transformed into a sol-gel state. The softening effect on muscle, tendon, and some pathological changes related to tissue dehydration. Such as rheumatoid arthritis lesions and the treatment of degenerative lesions of joints, tendons and ligaments.
C. Cavitation: cavitation is formed, either by unidirectional vibration that remains stable, or secondary to swelling to the point of collapse, with altered cellular function and increased intracellular calcium levels. Fibroblasts are activated, protein synthesis increases, vascular permeability increases, angiogenesis is accelerated, and collagen tension increases.
D. Polymerization and depolymerization: water molecule polymerization is the process of synthesizing multiple identical or similar molecules into one larger molecule. Macromolecular depolymerization is the process of turning a large chemical molecule into a smaller one. It can lead to increased hydrolase and proenzyme activity in the joints.
E. Anti-inflammatory, repair of cells and molecules: the ultrasound effect can make the tissue PH value to the alkaline side. Relieves local acidosis associated with inflammation. Ultrasound can affect blood flow, produce inflammation-causing effects, inhibit and play an anti-inflammatory role. Mobilizes leukocytes and promotes angiogenesis. Collagen synthesis and maturation. Promotes or inhibits the repair and healing process of damage. This results in the process of cleansing, activating and repairing damaged cells and tissues.
Infrasound:
Because the frequency of infrasound is very low, the absorption coefficient of the atmosphere for infrasound is very small, thus its penetration is very strong, and it can propagate to a very long distance with very little attenuation of energy. infrasound below 10Hz can propagate to a distance of thousands of kilometers. in the summer of 1983, the Krakatoa volcano, which is located between the islands of Sumatra and Java in Indonesia, erupted, and the powerful infrasound waves generated during the eruption circled around the island. In the summer of 1983, Krakatoa, a volcano located between Sumatra and Java in Indonesia, erupted, and the strong infrasound generated by the eruption circled the Earth three times, lasting 108 hours before it slowly faded away. The world's microbarometers have recorded its vibration aftermath. January 29, 1986, the U.S. Space Shuttle "Challenger" lift-off explosion, the explosion generated by the infrasound lasted 12 hours and 53 minutes, the explosion of the power of the strong, even more than 10,000 kilometers away from China's Beijing, Beijing, the Chinese Academy of Sciences Acoustic Research Institute of the monitoring station monitor are "listening" to it. The usual sound insulation and sound absorption methods for infrasound waves of the special penetrating power of the role of very little, 7000 Hz sound waves with a piece of paper can be blocked, and 7Hz infrasound with a thick wall can not be blocked, infrasound can penetrate more than a dozen meters thick reinforced concrete.
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