What is the hardest substance in the human body? Detailed answer

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What is the hardest substance in the human body? Detailed answer

Big encyclopedia for children and adults

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What is the hardest substance in the human body?

Tooth enamel. It consists mainly of calcium phosphate and carbonate compounds, as well as a small amount of silicic salts: hydroxyapatite (up to 75%), carbonate apatite, fluorapatite, chlorapatite, etc.

Author: Mendeleev V.A.

Random interesting fact from the Great Encyclopedia:

Who invented the broom?

A broom and a brush are somewhat similar to each other. Of course, the broom is only used for sweeping. Many brushes are also used for this purpose, although they were invented many thousands of years before the broom.

The caveman used brushes made from bundles of animal hair tied to the end of a stick. A kitchen whisk was a bundle of branches, reeds or wood bast tied to a long handle. In colonial times in America, just such brooms were used. And in many countries of today's Europe one can see how streets and floors in houses are swept with such brooms.

The broom known to us today is made of millet stalks. It was first made in America. Either true or not, but there is a legend about its origin. According to legend, a friend of Benjamin Franklin sent one of the clothes brushes made in that country from India. The brush was very similar to a small whisk. Several grains got stuck in the brush, and Franklin planted them in the ground. They took over, and within a few years the crop had spread throughout America.

One day, an old bachelor from Hadley, Massachusetts, needed a new broom. He cut millet stalks, tied them together, and swept the floors in his house. After that, he never used a birch broom again. He began to make these panicles and sold them to his neighbors. When he died in 1843, broom making was already an important industry. About a thousand acres of this plant were grown in Hadley every year. Until now, the main work in the manufacture of panicles is done manually.

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Random news from the Archive

Artificial photosynthesis system for methane production 23.12.2013

Panasonic does more than just produce electronic products. One of the areas of its activity is also promising alternative energy. For a long time, the Japanese manufacturer has been working on the study of artificial photosynthesis. And in early December, the work was crowned with significant success. Researchers have invented a system capable of generating methane from water and carbon dioxide using solar energy.

As part of the exhibition of green technologies Eco-Products 2013, Panasonic presented its development to the public for the first time. Details of the novelty are not disclosed, although the source published an image of the system showing some of its main parts. To date, the installation efficiency is 0,04% (the ratio of the total energy of synthesized methane to the consumed solar energy). To commercialize the development, it is enough to increase this value to 1%. It should be noted that earlier Panasonic already had a successful experience in designing an artificial photosynthesis system for the production of formic acid.

The Panasonic project is indicative and clearly reflects the Japanese government policy aimed at supporting green technologies in every possible way. In 2012, several government projects were opened one after another in Japan to accelerate the study and development of artificial photosynthesis.

Projects are coordinated by the Director of the Photosynthesis Research Center at the University of Tokyo.

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