Electric motors and their switching devices. Application area

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Section 5. Electric power plants

Electric motors and their switching devices. Application area

Free technical library

Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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5.3.1. This chapter of the Rules applies to electric motors and their switching devices in stationary installations of industrial and other premises for various purposes. These installations are also subject to the requirements given in 5.1.11, 5.1.13, 5.1.17, 5.1.19 and the corresponding requirements of other chapters, to the extent that they are not modified by this chapter.

See other articles Section Rules for the installation of electrical installations (PUE).

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Magnetic particles pollute the brain 23.09.2016

Particles of magnetite - a mineral with magnetic properties - are often found in living organisms, and in this connection they usually speak of a magnetic feeling: allegedly, magnetite, moving under the action of a geomagnetic field, irritates receptor cells, and thus animals learn where the north is, where is the south, and where in general they are. The human body also has magnetite: particles of it were found in the brain about a quarter of a century ago, and recently Joe Kirschvink, the geophysicist at the California Institute of Technology who discovered "human magnetite", reported that our brain can also sense a magnetic field.

However, magnetite has a significant disadvantage - it stimulates the appearance of aggressive oxidizing molecules that damage cellular proteins, lipids and DNA. On the other hand, it is known that an increased content of magnetite particles occurs in the brain of patients with Alzheimer's syndrome, and that magnetite somehow enhances the toxicity of pathogenic protein complexes formed in nerve cells in this disease. And at the same time, it is believed that all of our magnetite is biogenic, that is, created by the body itself through some kind of biochemical reactions. And then the question arises whether magnetite particles are really needed for geomagnetic feeling - maybe they accumulate only because some pathological processes begin in the brain, and the nervous system cannot cope with the collection of dangerous debris.

However, everything is actually simpler: in an article in PNAS, researchers from Lancaster University write that our magnetite may be ordinary industrial pollution that has entered the brain from the external environment. Barbara Maher and her colleagues from Oxford, the universities of Glasgow, Manchester, the University of Montana and the National Autonomous University of Mexico City analyzed post-mortem brain samples taken from dozens of people living in Mexico City and Manchester. There was magnetite in the samples, but for the most part it didn't look biological at all.

If a magnetite particle is formed in a cell, then its shape is a tetrahedron or an octahedron, but those found in the brains looked rounded, spherical. Such nanospheres are obtained with strong heating - for example, when fuel is burned in car engines or simply on an open fire. Biogenic tetrahedra and octahedra also existed, but for one biogenic particle there were at least a hundred abiogenic particles that entered the brain from the external environment. Along the way, particles of platinum, nickel and cobalt were found in the nervous tissue, which could not enter the human body from anywhere, except from the outside.

The size of all "external" particles is about 150 nanometers, so they are quite capable of entering the brain through the nose and olfactory nerve pathways. It is known that in the air of large cities, and especially along roads, many magnetite particles fly, so that local residents can easily breathe in "magnetic nanodust". Whether this gives special sensitivity to the magnetic field is not known; but in general, taking into account what has been said above about the connection between magnetite and Alzheimer's disease, the more pressing question here is how to remove or neutralize particles that have entered the brain so that they do not have time to harm nerve cells.

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