One hundred million tonnes of O are gotten from air for industrial uses every year. Industries use two main methods to make oxygen. The most common method is fractional distillation of liquefied air. N evaporates while O is left as a liquid. O is the second most important industrial gas.Because it is more economical , oxygen is usually stored and transported as a liquid. A small steel tank of 16 liters water capacity with a working pressure of 139 bar (2015 psi) holds about 2150 liters of gas and weighs 28 kilograms (62 lb) empty. 2150 liters of oxygen weighs about 3 kilograms (6.6 lb).
The other main method of making oxygen is by passing a stream of clean, dry air through a pair of zeolite molecular sieves. The zeolite molecular sieves soaks up the nitrogen. It gives a stream of gas that is 90% to 93% oxygen.
Oxygen gas can also be made through electrolysis of water into molecular oxygen and hydrogen.
Oxygen's NFPA 704 says that compressed oxygen gas is not dangerous to health and is not flammable.
At high pressures, oxygen gas (O) can be dangerous to animals, including humans. It can cause convulsions and other health problems. Oxygen toxicity usually begins to occur at pressures more than 50 kilopascals (kPa), equal to about 50% oxygen in the air at standard pressure (air on Earth has around 20% oxygen).
Premature babies used to be placed in boxes with air with a high amount of O. This was stopped when some babies went blind from the oxygen.
Breathing pure O in space suits causes no damage because there is a lower pressure used.
Concentrated amounts of pure O can cause a quick fire. When concentrated oxygen and fuels are brought close together, a slight ignition can cause a huge fire. The Apollo 1 crew were all killed by a fire because the air of the capsule had a very high amount of oxygen.
If liquid oxygen is spilled onto organic compounds, like wood, it can explode.
Blood
Blood is a liquid in humans and many animals. Blood is pushed through the organism by the heart, and brings nutrients and oxygen to our tissues. It also takes away waste and carbon dioxide from tissues.
Blood is made up of blood plasma and various cells — red blood cells, white blood cells and platelets. "Platelets" help blood to clot. Hemoglobin is in red blood cells. White blood cells help fight infections and heal wounds.
Blood plasma is the yellow liquid in which blood cells float. Plasma is made up of nutrients, electrolytes (salts), gases, non-protein hormones, waste, lipids, and proteins.
These proteins are albumin, antibodies (also called "immunoglobulins"), clotting factors, and protein hormones. Plasma that does not have the protein fibrinogen is called serum and cannot clot. Adults have about 3 liters of plasma. Plasma is a liquid, mostly water (90%). Plasma takes up 55% of blood volume.
Another name for red blood cell is "erythrocyte". 'Erythro' means red; 'cyte' means cell. RBC is an acronym for red blood cell.
RBCs carry oxygen and carbon dioxide around our body. Cells in our body need oxygen to live. Cells also make carbon dioxide as a waste. RBCs bring more oxygen around the body. They also take away the carbon dioxide.
RBCs are filled with haemoglobin. This is a protein. It is made to carry a large amount of oxygen. Haemoglobin has iron in it. The iron and oxygen gives haemoglobin its red color. This is why blood is red. Erythropoietin promotes the creation of RBCs. Blood type antigens are carried on the surface of red cells.
RBCs also help the blood stay normal pH. The blood needs a to be at a pH of 7.4. If it is much more or less than 7.4 a person can get very sick or die. RBCs are a buffer for the blood pH. Buffer means that it stops changes in pH. The proteins and the carbon dioxide in the RBC are buffers for the blood.
If you do not have enough RBCs, you will die.
White blood cells are a big part of the immune system. They attack things that do not belong in the body. They kill germs such as bacteria and viruses. They kill cancer cells. White blood cells also help to fight other toxic substances.
White blood cells find where the germs are, and start to destroy them. WBCs arrive in the blood. They also go out of the blood in places where there is infection. WBCs do this to fight the germs that make the infection. If they go out of the blood to fight an infection, they may return in the lymphatic system. So WBCs are in lymph nodes.
Another name for white blood cell is "leukocyte". Leuko means white. -cyte means cell. WBC is an acronym for white blood cell. There are three main kinds of WBCs. They are lymphocytes, granulocytes and monocytes. Some of the WBCs mature into cells which do similar work in the tissues.
The different WBCs work in different ways. Some WBCs kill and eat germs and cancer cells. Some WBCs make antibodies. These are proteins that stick to a cell and tell other WBCs to kill it. Some WBCs make chemicals. They release these chemicals to fight things that do not belong in the body. These chemicals cause inflammation in a part of the body. When a germ makes someone sick, the body shows it. If a bacteria gets under someone's skin and causes an infection, the skin gets red, hot, and painful. This redness, heat, and pain are signs of "inflammation". This shows that WBCs are fighting the infection and killing the bacteria.
Platelets help make blood clot. A clot is when the liquid blood becomes solid. The body makes blood clot when the skin is cut. This stops blood from going out of the skin too much.
For blood to be able to clot is essential. But, rarely, some blood clots are bad. If a blood clot happens in a blood vessel going to the brain, it can cause a stroke. If it happens in a blood vessel going to the heart, it can cause a heart attack. This does not usually happen to young, healthy people.
Platelets are not the only things that make clots. There are proteins in the blood that help make clots. Both platelets and "clotting proteins" are needed to make good clots.
Blood cells are made in the bone marrow and in the spleen. The bone marrow is the soft material in the middle of bones. Special cells in the bone marrow make most of the blood cells in your body.
Plasma proteins are made mostly by the liver. The water and electrolytes in plasma come from the food and water that you eat.
Although blood is a fluid, in some respects it is a kind of connective tissue. Its cells originate in bone marrow and the spleen, and in the blood there are potential molecular fibres in the form of fibrinogen. These are activated when a blood clot forms.
1960s
The 1960s was the decade that started on January 1, 1960 and ended on December 31, 1969. Many things happened in the sixties, including the Space Race, the Civil Rights Movement, and the Vietnam War.
The 1960s term also refers to an era more often called the Sixties. This was a set of cultural and political trends around the globe. This "cultural decade" is loosely defined as beginning around 1963 and ending around 1974.
The social revolution of the 1960s was part of a wider counterculture. Old ways were changed, new ways taken up. Typical was the introduction of the birth control pill, and its effect on sexual activity, widespread use of certain drugs and a general disrespect for traditional ways.
Pop art also started in the 1960s.
1970s
The 1970s was the decade that started on January 1, 1970, and ended on December 31, 1979.
1980s
The 1980s was the decade that started on January 1, 1980 and ended on December 31, 1989.