Life is a little knowledge of popular science
Tips for using diesel oil
The tractor running forward with black smoke uses diesel fuel. Ordinary diesel oil is an oil product that reaches a certain standard with petroleum crude oil as raw material and smelting technology. People often see light diesel oil marked with No.0, 10, No.20 and No.32, indicating that their freezing points are not higher than 0℃,-10℃, -20℃ and -35℃ respectively. Suppose your car uses diesel as fuel. When using, different grades of light diesel oil should be selected according to different regions and seasons. Generally speaking, when the temperature is low, light diesel oil with low freezing point should be selected; On the contrary, light diesel oil with high freezing point should be selected, and the freezing point should be 5℃ lower than the local temperature.
Plug tip
Why do electric fans, washing machines, refrigerators and other household appliances mostly use three-wire plugs? What is the difference between a three-wire plug and a three-phase plug?
Three-phase electrical appliances refer to three different live wires, and the voltage between each two wires is 380 volts. They are generally used in power systems and are more common in industrial electricity consumption. Single-phase power supply is generally used in household appliances, and its three wires are live wire, neutral wire and ground wire. The voltage between the live wire and the neutral wire is 220 volts, so this is not three-phase electricity, and its plug socket is not a three-phase plug socket. The grounding wire is to ensure safety.
What if the tractor slips?
Tractor is a very important agricultural machinery, which is very common in rural areas. If you look at the tractor tires carefully, you will find that there are many bumps on the tires. Its purpose is to increase the friction between the tire and the ground, so that the tractor is not easy to slip when working in the field. The weight of tractor is also related to friction. In the same case, the heavier the tractor, the greater the friction. So when the tractor slips, it can be solved by increasing its weight. Because tractors and other agricultural machinery are powered by diesel, the high-concentration particulate matter emitted by them is suspended in the air for a long time and easily inhaled by human body, which has become one of the main pollution in the suburbs of cities.
Food in Harpy is poisonous.
In daily life, people often encounter food spoilage. The process of food spoilage is the process of decomposition and change of protein, carbohydrate and fat in food, and its degree varies with different kinds of food, types and quantities of microorganisms and environmental conditions. Usually, the deterioration of fat is mainly due to rancidity, which is a mutagenic pollution of food. Enzymes, ultraviolet rays and oxygen produced by microorganisms can decompose neutral fats in food into glycerol and fatty acids, and fatty acids are further decomposed into peroxides and oxides, followed by rancidity products such as ketones and aldehydes, which have a special pungent smell, that is, the so-called spicy taste. Eating food that has been stored for a long time because it is unsalable can lead to poisoning. The main clinical manifestations are gastrointestinal symptoms, and some patients may have dizziness, headache, abdominal distension, diarrhea, abdominal pain, nausea, vomiting and other symptoms.
The utility of functional food needs to be verified.
With the development of economy and the progress of science, people are no longer satisfied with "eating enough", but advocate more scientific and multifunctional health food that is beneficial to human health. What is functional food? European experts from the International Institute of Life Sciences said: "If a food can be convincingly proved to be beneficial to one or more functions of the body, and it has enough nutrition to improve health or reduce diseases, then it can be called functional food." Functional food and general food can provide basic nutrients necessary for human survival (the first function of food), and have specific color, fragrance, taste and shape (the second function of food). However, functional foods contain a certain amount of functional ingredients (physiologically active substances), which can regulate human functions (the third function of food); Functional food generally has a specific scope of consumption (specific population), and general food has no specific scope of consumption.
It should be pointed out that the research and development of functional food at home and abroad is still in its infancy, and its effectiveness needs further verification. Nowadays, many advertisements are exaggerated, so consumers should not blindly listen to the propaganda of advertisements. Scientifically speaking, paying attention to a balanced diet at ordinary times, such as a diversified healthy diet composed of a large number of fresh fruits, vegetables, vitamins and crude fiber foods, regular living habits, timely and moderate exercise and a happy mood, is the fundamental guarantee of health.
Science and technology boost agricultural engineering.
With the increasing application of science and technology in agriculture, the fields and scope of agricultural engineering are becoming wider and wider. Such as agricultural water and soil engineering, agricultural mechanization and automation engineering, agricultural electronics and information technology, post-harvest processing and treatment engineering of agricultural products, facility agriculture and environmental control engineering, rural energy, agricultural waste treatment and environmental protection engineering. Modern agricultural engineering not only creates production benefits far higher than traditional agriculture, but also shows exciting agricultural production prospects. With the help of advanced engineering technology, people can not only see tomato trees bearing tens of thousands of fruits, but also see tractors equipped with air conditioning, computers, GIS, GPS and rs systems being used for fixed-point formula fertilization and fixed-point spraying weeding in the field.
Energy is closely related to human development.
People have long known that energy can neither be created nor destroyed. So where does the energy come from? Energy exists in different forms and comes from different sources. We divide energy into two types: non-renewable energy and renewable energy. Non-renewable energy resources refer to those resources that cannot be recovered in a short time once consumed, such as coal, oil and natural gas. According to the detection, according to the current consumption rate, oil, natural gas and coal will be exhausted in 45, 60 and 250 years respectively. The opposite of "non-renewable energy" is "renewable energy", such as wind energy, tidal energy, solar energy and hydropower. These energy sources are inexhaustible, and they are also called "clean energy" because they have no pollution to the environment during use. Because the non-renewable energy on the earth is limited, people should pay more attention to the generation, storage and transportation of renewable energy.
The progress of human beings from ancient times to the peaceful use of nuclear energy today is actually a process of constantly absorbing and utilizing energy from nature. Energy is closely related to people's lives, and energy shortage is a common problem at present. For example, some residents often complain that power companies limit electricity and electricity prices rise; Car drivers complain about the rise in oil prices. Today, energy has become an important strategic resource, which plays an important role in stabilizing national economic, social and political security. The well-known Iraq war actually stems from the competition for energy. The implementation of major national projects, such as the Three Gorges Project and the West-East Gas Transmission Project, is to solve the increasingly serious energy shortage problem and meet the energy demand of rapid economic development. At present, people urgently need to save energy, rationally use energy and improve energy utilization efficiency, especially non-renewable energy.
What you must know about popular science II
What metal minerals are there in the stratum?
Metal minerals refer to rocks that can extract a certain amount of metals. In nature, only gold and copper exist independently, and they are not combined with other elements. In addition, most metals are extracted from ores. The earth provides us with many metal minerals, such as common copper and iron. By refining these minerals, we can get metals. Metal is an indispensable material in human production and life, while the reserves of gold, silver, platinum and other metals in the earth's crust are very small, also known as precious metals. They are the main materials for making ornaments, and the price is usually more expensive.
How are minerals formed?
Minerals are natural simple substances or compounds formed by geological processes. At present, there are more than 3,000 known minerals on the earth, but only more than 50 are the most common. Minerals are formed under certain physical and chemical conditions. When the external conditions change, the original minerals can change and form new minerals. The formation of minerals includes three forms: gas to solid, liquid to solid and solid to solid. The most common form from gaseous state to solid state is hydrogen sulfide gas ejected from volcano to form elemental sulfur, while liquid state to solid state is salt minerals formed by evaporation and crystallization in salt lakes, and solid state to solid state is mainly amorphous to crystalline minerals.
Where does the oxygen come from?
The existence of life is thanks to cyanobacteria, which completely changed the earth's atmosphere. They discharged oxygen as waste, making the earth's atmosphere full of oxygen for the first time 2.4 billion years ago. However, rock evidence shows that in the past 3 billion years, the oxygen level increased and decreased rapidly like a roller coaster, and gradually stabilized until 54.48 billion years ago in Cambrian. Are bacteria contributors to oxygen in the earth's atmosphere? Or are there other influencing factors? Understanding how the oxygen-enriched atmosphere is formed is a key factor to decipher the history of life development on earth.
Do you know what the solar wind is?
During the total solar eclipse, a circle of pale yellow light will appear on the surface of the black sun. This phenomenon is called corona. The corona extends millions of kilometers from the surface of the sun. The corona consists of gases as high as 65438+500,000℃.
The charged particles (positrons and electrons) that form the corona flow around the earth at a speed of 500 kilometers per second. This is the so-called solar wind. The solar wind also circulates around the earth at 200,000 ~ 300,000 degrees Celsius, and it is very terrible because it is a stream of charged particles. Fortunately, the earth's magnetic field acts as a barrier to protect the earth from the influence of the solar wind.
Because the earth is a magnetic field, the charged particles of the solar wind surround the earth, thus forming a strong radiation belt, which is the Van Allen radiation belt.
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