Editing Sam Ruben (section)

==Research==
Ruben and colleague [[Martin Kamen]], a [[University of Chicago]] Ph.D. and researcher in chemistry and [[nuclear physics]] working under [[Ernest O. Lawrence]] at the [[Berkeley Radiation Laboratory]], set out to elucidate the path of carbon in [[photosynthesis]] by incorporating the short-lived radioactive isotope [[carbon-11]] ({{chem|11|CO|2}}) in their many experiments between 1938 and 1942.  Aided by the concepts and collaboration of [[C. B. van Niel]], at [[Stanford University]]'s [[Hopkins Marine Station]], it became clear to them that reduction of CO{{sub|2}} can occur in the dark and may involve processes similar to bacterial systems. This interpretation challenged the century-old [[Adolf von Baeyer]] theory of photochemical reduction of CO{{sub|2}} adsorbed on [[chlorophyll]] which had guided decades of effort by [[Richard Willstätter]], [[Arthur Stoll]], and many others in vain searches for [[formaldehyde]].

In hundreds of experiments with carbon-11 produced from [[deuterons]] and boron-10 by Kamen in the Radiation Laboratory's 37-inch [[cyclotron]], Ruben and Kamen, with collaborators from [[botany]], [[microbiology]], [[physiology]] and [[organic chemistry]], pursued the path of carbon dioxide in plants, algae, and bacteria.  Their results, confused by absorption of the products on proteinaceous residues, initially failed to reveal the path of carbon in photosynthesis but succeeded in exciting the interest of scientists worldwide in the search and revelation of metabolic processes, beginning a revolution in [[biochemistry]] and medicine.

Ruben's experiments using 'heavy water', {{chem2|H2^{18}O}}, to yield {{chem|18|O|2}} gas had shown that the [[oxygen]] gas produced in photosynthesis comes from water.  With nuclear physicists' tenuous prediction of a "long-lived radioactive carbon isotope", Ruben and Kamen pursued several routes that could lead to identification of the [[carbon-14]] isotope.  After several failed attempts, Kamen collected the results of a 120-hour [[cyclotron]] bombardment of graphite and trudged in the rain with it to the "Rat House", adjacent both to the chemistry department and to the [[cyclotron]], and Ruben's desk.  At 8&nbsp;am, February 27, 1940, Ruben demonstrated unequivocally that the radioactivity was from carbon-14.{{citation needed|date=February 2016}}

Use of carbon-14 in tracer experiments was hindered by the difficulty measuring the weak beta emission of the radioactive decay and by the onset of World War II that shut off production of the isotope. In 1942 Ruben was assigned to work on war related research away from Berkeley. Further, Kamen was removed from his position at Berkeley due to allegations he was a security risk. Ruben fully realized the potential use of this isotope and was committed to working to elucidate the mechanism of photosynthetic carbon fixation using carbon-14. Instead, Ruben gave all his barium carbonate-{{sup|14}}C to chemistry department faculty member [[Andrew Benson]] who began his long series of {{chem|14|CO|2}} fixation experiments to determine the path of carbon in photosynthesis.  Only in 1949 did chemist [[Willard Libby]] use it to invent [[radiocarbon dating]].

Ruben's recruitment for research in the World War II wartime effort led him to interest in the mechanism of [[phosgene]] as a poisonous gas.  With C-11 phosgene ({{chem|11|COCl|2}}) prepared by Benson, they studied the combination of phosgene with lung proteins.  Following Benson's departure from Berkeley in July 1943, Ruben died September 28, 1943, after a disastrous exposure to phosgene in a laboratory accident the preceding day.

Sam Ruben married Helena Collins West, a fellow chemistry student, during his final semester as an undergraduate at UC Berkeley, on September 28, 1935.  They had three children: Dana West Ruben (born November 11, 1938), George Collins Ruben (born April 29, 1941), who became a professor at [[Dartmouth College]],<ref>{{cite journal|author=Gest, Howard|title=Samuel Ruben's contributions to research on photosynthesis and bacterial metabolism with radioactive carbon|journal=Photosynthesis Research|volume=80|pages=77–83|year=2004|issue=1–3|url=http://www.life.illinois.edu/govindjee/Part3/9_Gest_On_Ruben.pdf|doi=10.1023/b:pres.0000030438.72496.2c|pmid=16328812|bibcode=2004PhoRe..80...77G |s2cid=12186280}}</ref> and Connie Mae Ruben Fatt (born June 18, 1943).