In the 18th century, Pierre Louis Maupertuis made experiments with scorpion venom and saw that certain dogs and mice were immune to this venom. This and other observations of acquired immunity led to Louis Pasteur (1822–1895) developing vaccination and the germ theory of disease. Pasteur's theory was in direct opposition to contemporary theories of disease, such as the miasma theory. It was not until the proofs Robert Koch (1843–1910) published in 1891 (for which he was awarded a Nobel Prize in 1905) that microorganisms were confirmed as the cause of infectious disease. Viruses were confirmed as human pathogens in 1901, when the yellow fever virus was discovered by Walter Reed (1851–1902).
Immunology made a great advance towards the end of the 19th century, through rapid developments, in the study of humoral immunity and cellular immunity. Particularly important was the work of Paul Ehrlich (1854–1915), who proposed the side-chain theory to explain the specificity of the antigen-antibody reaction. The Nobel Prize for 1908 was jointly awarded to Ehrlich and the founder of cellular immunology, Ilya Mechnikov (1845–1916).
The immune system is extremely ancient, and may go back to single-celled eukaryotes which needed to distinguish between what was food and what was part of themselves.
Sulfur hexafluoride
Sulfur hexafluoride, also known as sulfur(VI) fluoride, is a chemical compound. Its chemical formula is SF. It contains sulfur in its +6 oxidation state. It also contains fluoride ions.
BBC News says "It's the most powerful greenhouse gas known to humanity, and emissions have risen rapidly in recent years. Sulphur hexafluoride, or SF6, is widely used in the electrical industry to prevent short circuits and accidents. Leaks of the little-known gas in the UK and the rest of the EU in 2017 were the equivalent of putting an extra 1.3 million cars on the road".
Sulfur hexafluoride is a colorless, odorless gas. It is very heavy for a gas (about 5 times heavier than air). It is non reactive, and hard to find anything that reacts with it. It is a strong greenhouse gas. This has made people put some restrictions on using it.
It is made by reacting sulfur with fluorine. That combination also makes toxic disulfur decafluoride, which has to be removed.
It is used in electronics and various electrical devices. It can be used in the body since it is not toxic. It can be used as a test gas to look where gas flows in a heater system, for example. It is detected easily. It is used in some torpedoes. Lithium is one of the only things that reacts with sulfur hexafluoride. Sulfur hexafluoride is sprayed on lithium. This makes the lithium very hot. It creates steam from water and shoots the torpedo. It can be breathed in to make the voice deeper. This is the opposite of breathing in helium gas.
Sulfur hexafluoride is not toxic. It can fill up in closed spaces though. A person may suffocate in the closed space if sulfur hexafluoride has pushed out the oxygen from the space.
According to the Intergovernmental Panel on Climate Change, is the most potent greenhouse gas that it has evaluated, with a global warming potential (GWP) of 22,800 times that of when compared over a 100-year period. Measurements of SF show that its global average mixing ratio has increased by about 0.2 ppt per year to over 7 ppt. Sulfur hexafluoride is also extremely long-lived. It is inert in the troposphere and stratosphere. It has an estimated atmospheric lifetime of 800–3200 years. is very stable. (For countries reporting their emissions to the UNFCCC, a GWP of 23,900 for was suggested at the third Conference of the Parties: GWP used in Kyoto protocol). Average global SF concentrations increased by about seven percent per year during the 1980s and 1990s, mostly as the result of its use in the magnesium production industry, and by electrical utilities and electronics manufacturers. Given the low amounts of SF released compared to carbon dioxide, its overall contribution to global warming is estimated to be less than 0.2 percent.
In Europe, falls under the F-Gas directive which ban or control its use in several ways. Since 1 January 2006, is banned as a tracer gas and in all applications except high-voltage switchgear.
Salt
Gallery
An art gallery is a place where art is displated. Gallery may also refer to:
Disulfur decafluoride
Disulfur decafluoride, also known as sulfur pentafluoride and sulfur(V) fluoride, is a chemical compound. Its chemical formula is SF. It contains sulfur in its +5 oxidation state.
Disulfur decafluoride is a colorless liquid. It has no odor. It is very toxic. It disproportionates to sulfur hexafluoride and sulfur tetrafluoride when heated. It reacts with sulfur dioxide. It also can react with chlorine, bromine, and ammonia. It is more toxic than phosgene.
It was thought of as a poison gas in World War II, but it was never used. It has almost no uses.
List of Formula One Grand Prix winners
Formula One, abbreviated to F1, is a form of open-wheeled auto racing. It is the highest class defined by the Fédération Internationale de l'Automobile (FIA), motorsport's world governing body. The "formula" in the name refers to a set of rules. These rules tell the builders and drivers of the cars what they may and may not do. The F1 world championship season is a series of races. These races are known as Grands Prix. They are usually held on purpose-built circuits. In a few places, they are held on closed city streets. The most famous Grand Prix is the Monaco Grand Prix in Monte Carlo. The top finisher of each race are awarded championship points. The points are added up at the end of they year. There are two yearly Championships. The one for drivers and one for constructors.
Michael Schumacher holds the record for the most Grand Prix victories. He has won 91 times. Alain Prost is second with 51 wins, and Ayrton Senna is third with 41 wins. Michael Schumacher also has the longest time between his first win and his last. He won his first Grand Prix in at the Belgian Grand Prix, and his last in at the Chinese Grand Prix, a span of 14 years, 1 month and 1 day. The youngest winner of a Grand Prix is Sebastian Vettel, who was 21 years, 73 days old when he won the Italian Grand Prix in . Luigi Fagioli is the oldest winner of a Formula One Grand Prix. He was 53 years and 22 days old when he won the French Grand Prix.
As of the , there have been 109 different Formula One Grand Prix winners. The 100th Grand Prix winner was Heikki Kovalainen at the Hungarian Grand Prix. 746 drivers have started a Grand Prix race.
"All figures correct as of the 2016_Australian_Grand_Prix"
List of races won by nationality of driver.
"All figures are correct as of 31 July 2011.
Turdidae
The Turdidae are a family of passerine songbirds, the thrushes. It includes the common song thrush and the blackbird.
Paridae
The Paridae is a family of tiny birds, the tits (called 'chickadees' or 'titmice' in North America). They are passerine songbirds which are native to the northern hemisphere and Africa. Most of them used to be classified in the genus "Parus", which has now been split up.
These birds are mainly small stocky woodland species with short stout bills. Some have crests. They range in length from 10 to 22 centimetres. They are adaptable birds, with a mixed diet including seeds and insects.
Many species will live around human habitation and come readily to bird feeders for nuts or seed, and learn to take other foods. In Britain, great tits and blue tits learned to break through the foil caps sealing bottles of milk on doorsteps, to get at the cream on top. Of course, the change in milk packaging has robbed them of this delicacy.
These are hole-nesting birds, typically using trees, although some species build nests on the ground. They lay anything from three to nineteen speckled white eggs, depending on species.