In the cold winter days, people in the daily diet should follow three principles, that is, through the diet can play a role in insulation, keep cold and prevent dryness. Therefore, people should pay more attention to supplementing heat-source foods and increase the supply of heat energy to improve the body's tolerance to low temperatures. Such foods include carbohydrates, fats, and proteins, among which foods rich in high-quality protein should be considered, such as Lean meat, chicken, duck, eggs, fish, milk, soy products.
Second, we must add more food containing methionine and inorganic salts to improve the body's ability to keep out the cold. Methionine provides a series of methyl groups necessary for adaptation to cold by transfer. The cold climate makes the excretion of creatine in the urine of the human body increase, and the metabolism of fat is accelerated. The synthesis of creatine and fatty acids, and the release of heat from phospholipids in the mitochondria, all require the methyl group to release heat. Therefore, more foods containing methionine, such as sesame, sunflower seeds, yeast, dairy products, leafy vegetables, etc., should be ingested in winter. In addition, medical research shows that people are afraid of the cold and the lack of dietary inorganic salts. Therefore, winter should be more intake of vegetables containing roots, such as carrots, lilies, hawthorn, Chinese wolfberry and green vegetables, Chinese cabbage, etc., because the root vegetables contain more inorganic salts. The amount of calcium in the human body can directly affect the expansion and excitability of the human heart muscle, blood vessels and muscles. Supplemental calcium can also improve the body's cold resistance. Foods containing more calcium are: milk, soy products, shrimp, kelp, seaweed, sesame and so on.
Third, we must eat more foods rich in vitamin B2, vitamin A, vitamin C, to prevent the occurrence of angular cheilitis, cheilitis, glossitis and other diseases. The cold climate makes the body's oxidative function strengthen, and the body's vitamin metabolism also changes significantly, prone to dry skin, chapped and angular cheilitis, and cheilitis. Therefore, vitamin B2 should be added in a timely manner in the diet, which mainly exists in animal liver, eggs, milk, beans and other foods; foods rich in vitamin A include animal liver, carrots, pumpkin, red heart and sweet potatoes and other foods; vitamin C is mainly Exist in fresh vegetables and fruits.
Ultrasonic waves propagate in the liquid, causing the liquid and the cleaning tank to vibrate together at the ultrasonic frequency. When the liquid and the cleaning tank vibrate, they have their own natural frequency. This vibration frequency is the sound wave frequency, so people hear the buzzing sound. With the continuous development of the cleaning industry, more and more industries and enterprises have used ultrasonic cleaning machines.
For the principle of ultrasonic cleaning machine, the high-frequency oscillation signal sent by the ultrasonic generator is converted into high-frequency mechanical oscillation by the transducer and propagated to the medium-the cleaning solvent. The ultrasonic wave radiates forward in the dense and dense phases in the cleaning liquid. The flow of liquid produces tens of thousands of tiny bubbles with a diameter of 50-500μm, and the tiny bubbles existing in the liquid vibrate under the action of the sound field. These bubbles form and grow in the negative pressure zone where the ultrasonic wave propagates longitudinally. In the positive pressure zone, when the sound pressure reaches a certain value, the bubbles increase rapidly and then suddenly close. And when the bubble is closed, a shock wave is generated, and thousands of atmospheres are generated around it, destroying insoluble dirt and dispersing them in the cleaning liquid. When the group particles are wrapped in oil and adhere to the surface of the cleaning part, the oil is emulsified and solid Particles and detachment, so as to achieve the purpose of cleaning parts purification. In this process known as the "cavitation" effect, the closed bubble can form a high temperature of several hundred degrees and an instantaneous high pressure of more than 1,000 atmospheres.
The advantages of the ultrasonic cleaning machine are: the ultrasonic cleaning effect is good, and the operation is simple. The sound that people hear is a sound wave signal with a frequency of 20-20000 Hz. The sound wave above 20000 Hz is called an ultrasonic wave. The transmission of the sound wave propagates longitudinally according to a sinusoidal curve, producing a large number of small bubbles. One reason is that partial tensile stress occurs in the liquid to form negative pressure. The decrease in pressure makes the gas originally dissolved in the liquid supersaturate and escape from the liquid and become small bubbles; the other reason is that the strong tensile stress tears the liquid apart. "A void is called cavitation.
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