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Kaydee
OUTER SPACE
~2.0 mins read
Outer space , or simply space, is the expanse that exists beyond Earth and between celestial bodies . Outer space is not completely empty—it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation , magnetic fields, neutrinos, dust, and
cosmic rays. The baseline temperature of outer space, as set by the background radiation from the Big Bang , is 2.7 kelvins (−270.45 °C; −454.81 °F). [1] The plasma between galaxies accounts for about half of the baryonic (ordinary) matter in the universe; it has a
number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins. [2] Local concentrations of matter have condensed into stars and galaxies. Studies indicate that 90% of the mass in most galaxies is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces .[3][4] Observations suggest that the majority of the
mass-energy in the observable universe is dark energy , a type of vacuum energy that is poorly understood. [5][6] Intergalactic space takes up most of the volume of the universe , but even galaxies and star systems consist almost entirely of empty space.
The interface between the Earth's surface and outer space. The Kármán line at an altitude of 100 km (62 mi) is shown. The layers of the atmosphere are drawn to scale, whereas objects within them, such as the International Space Station , are not.
Outer space does not begin at a definite altitude above the Earth's surface. The Kármán line, an altitude of 100 km (62 mi) above sea level, [7][8] is conventionally used as the start of outer space in space treaties and for aerospace records keeping. The framework for international space law was established by the
Outer Space Treaty , which entered into force on 10 October 1967. This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space. Despite the drafting of UN resolutions for the peaceful uses of outer space, anti-satellite weapons have been tested in Earth orbit.
Humans began the physical exploration of space during the 20th century with the advent of high-altitude balloon flights . This was followed by manned rocket flights and, then, manned Earth orbit , first achieved by Yuri Gagarin of the Soviet Union in 1961. Due to the high cost of getting into space, manned spaceflight has been limited to low Earth orbit and the Moon . On the other hand, unmanned spacecraft have reached all of the known planets in the Solar System.
Outer space represents a challenging environment for human exploration because of the hazards of vacuum and radiation .
Microgravity also has a negative effect on human physiology that causes both muscle atrophy and bone loss. In addition to these health and environmental issues, the economic cost of putting objects, including humans, into space is very high.
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Kaydee
Vitamin
~2.4 mins read
A vitamin is an organic molecule (or a chemically closely related set of molecules, i.e.
vitamers ) that is an essential micronutrient which an organism needs in small quantities for the proper functioning of its metabolism . Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet . Vitamin C can be synthesized by some species but not by others; it is not a vitamin in the first instance but is in the second. The term vitamin does not include the three other groups of essential nutrients : minerals,
essential fatty acids , and essential amino acids . [2] Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, vitamin E consists of four tocopherols and four tocotrienols . Some sources list fourteen vitamins, by including
choline , [3] but major health organizations list thirteen: vitamin A (as all- trans- retinol, all- trans-retinyl-esters, as well as all- trans -beta-carotene and other provitamin A carotenoids), vitamin B 1 ( thiamine), vitamin B 2 ( riboflavin), vitamin B 3 ( niacin), vitamin B 5 ( pantothenic acid ), vitamin B 6 ( pyridoxine), vitamin B 7 ( biotin), vitamin B 9 ( folic acid or folate), vitamin B 12 ( cobalamins ), vitamin C ( ascorbic acid), vitamin D (calciferols ),
vitamin E ( tocopherols and tocotrienols ), and
vitamin K ( phylloquinone and menaquinones). [4]
[5][6]
Vitamins have diverse biochemical functions. Vitamin A acts as a regulator of cell and tissue growth and differentiation. Vitamin D provides a hormone-like function, regulating mineral metabolism for bones and other organs. The B complex vitamins function as enzyme cofactors (coenzymes) or the precursors for them. Vitamins C and E function as antioxidants. [7] Both deficient and excess intake of a vitamin can potentially cause clinically significant illness, although excess intake of water-soluble vitamins is less likely to do so.
Before 1935, the only source of vitamins was from food[citation needed ]. If intake of vitamins was lacking, the result was vitamin deficiency and consequent deficiency diseases. Then, commercially produced tablets of yeast-extract vitamin B complex and semi-synthetic vitamin C became available [citation needed ]. This was followed in the 1950s by the mass production and marketing of vitamin supplements , including
multivitamins , to prevent vitamin deficiencies in the general population. Governments mandated addition of vitamins to staple foods such as flour or milk, referred to as food fortification, to prevent deficiencies. [8] Recommendations for
folic acid supplementation during pregnancy reduced risk of infant neural tube defects.[9]
The term vitamin is derived from the word
vitamine, which was coined in 1912 by Polish biochemist Casimir Funk , who isolated a complex of micronutrients essential to life, all of which he presumed to be amines.[10] When this presumption was later determined not to be true, the "e" was dropped from the name. [11] All vitamins were discovered (identified) between 1913 and 1948[citation needed ].
Vitamins are classified as either water -soluble or fat-soluble . In humans there are 13 vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C). Water-soluble vitamins dissolve easily in water and, in general, are readily excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption. [24] Because they are not as readily stored, more consistent intake is important. [25] Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids (fats). Vitamins A and D can accumulate in the body, which can result in dangerous hypervitaminosis . Fat-soluble vitamin deficiency due to malabsorption is of particular significance in cystic fibrosis.[26
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