Editing Ultracentrifuge (section)

==History==
In 1924 [[Theodor Svedberg]] built a centrifuge capable of generating 7,000 g (at 12,000 rpm), and called it the ultracentrifuge, to juxtapose it with the [[Ultramicroscope]] that had been developed previously. In 1925-1926 Svedberg constructed a new ultracentrifuge that permitted fields up to 100,000 g (42,000 rpm).<ref name="Svedberg Lecture">{{cite web |url= https://www.nobelprize.org/prizes/chemistry/1926/svedberg/lecture/ |title= Svedberg Lecture |access-date=2019-02-18 }}</ref> Modern ultracentrifuges are typically classified as allowing greater than 100,000 g.<ref>{{cite web |url= https://www.beckman.com/centrifuges |title= Beckman Centrifuges |access-date=2019-02-18 }}</ref> Svedberg won the [[Nobel Prize in Chemistry]] in 1926 for his research on colloids and proteins using the ultracentrifuge.<ref>{{cite web |url= http://www.rsc.org/chemsoc/timeline//pages/1925.html |title= Svedberg |access-date=2010-06-23 }}</ref><ref name="RosenGothard2009">Joe Rosen; Lisa Quinn Gothard. ''[https://books.google.com/books?id=avyQ64LIJa0C Encyclopedia of Physical Science]''. Infobase Publishing; 2009. {{ISBN|978-0-8160-7011-4}}. p. 77.</ref><ref name="Svedberg Lecture"/>

In early 1930s, [[Émile Henriot (chemist)|Émile Henriot]] found that suitably placed jets of compressed air can spin a bearingless top to very high speeds and developed an ultracentrifuge on that principle. [[Jesse Beams]] from the Physics Department at the [[University of Virginia]] first adapted that principle to a [[high-speed camera]], and then started improving Henriot's ultracentrifuge, but his rotors consistently overheated.<ref>{{cite web | url=https://www.beckman.com/resources/technologies/analytical-ultracentrifugation/history/light-beams | title=Light Beams }}</ref>

Beam's student [[Edward Greydon Pickels]] solved the problem in 1935 by [[vacuum]]izing the system, which allowed a reduction in [[friction]] generated at high speeds.  Vacuum systems also enabled the maintenance of constant [[temperature]] across the sample, eliminating [[convection current]]s that interfered with the interpretation of sedimentation results.<ref name=Elzen>Elzen B. ''Vacuum ultracentrifuge.'' In:  Encyclopedia of 20th-Century Technology, Colin Hempstead & William Worthington, eds. Routledge, 2005. p. 868.</ref>

[[File:Beckman model e hm50tr96s.tiff|thumb|right|Comparing Serial Numbers 1 and 1000 of Spinco's Model E Analytical Ultracentrifuge, 1965]]
In 1946, Pickels cofounded [[Spinco]] (Specialized Instruments Corp.) to market analytical and preparative ultracentrifuges based on his design. Pickels considered his design to be too complicated for commercial use and developed a more easily operated, “foolproof” version. But even with the enhanced design, sales of analytical centrifuges remained low, and Spinco almost went bankrupt. The company survived by concentrating on sales of preparative ultracentrifuge models, which were becoming popular as workhorses in biomedical laboratories.<ref name=Elzen/> In 1949, Spinco introduced the Model L, the first preparative ultracentrifuge to reach a maximum speed of 40,000 [[Revolutions per minute|rpm]]. In 1954, [[Beckman Instruments]] (later [[Beckman Coulter]]) purchased the company, forming the basis of its Spinco centrifuge division.<ref>Arnold O. Beckman: One Hundred Years of Excellence. By Arnold Thackray and Minor Myers, Jr. Philadelphia: Chemical Heritage Foundation, 2000.</ref>