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21 Abel, John Jacob
SUBJECT AREA: Medical technology[br]b. 19 May 1857 near Cleveland, Ohio, USAd. 26 May 1938 Baltimore, Maryland, USA[br]American pharmacologist and physiologist, proponent of the "artificial kidney" and the isolator of pure insulin.[br]Born of German immigrant farming stock, his early scientific education at the University of Michigan, where he graduated PhB in 1883, suffered from a financially dictated interregnum of three years. In 1884 he moved to Leipzig and worked under Ludwig, moving to Strasbourg where he obtained his MD in 1888. In 1891 he was able to return to the University of Michigan as Lecturer in Materia Medica and Therapeutics, and in 1893 he was offered the first Chair of Pharmacology at Johns Hopkins University, a position he occupied until 1932. He was a pioneer in emphasizing the importance of chemistry, in its widest sense, in medicine and physiology. In his view, "the investigator must associate himself with those who have laboured in fields where molecules and atoms rather than multi-cellular tissues or even unicellular organisms are the units of study".Soon after coming to Baltimore he commenced work on extracts from the adrenal medulla and in 1899 published his work on epinephrine. In later years he developed an "artificial kidney" which could be used to remove diffusible substances from the blood. In 1913 he was able to demonstrate the existence of free amino-acids in the blood and his investigations in this field foreshadowed not only the developments of blood and plasma transfusion but also the possibility of the management of renal failure.From 1917 to 1924 he moved to a study of the hormone content of pituitary extracts, but in 1924 he suddenly transferred his attention to the study of insulin. In 1925 he announced the discovery of pure crystalline hormone. This work at first failed to gain full acceptance, but as late as 1955 the full elucidation of the protein structure of insulin proved the final culmination of his studies.Abel's dedication to laboratory research and his disdain for matters of administration may explain the relative paucity of worldy honours awarded to such an outstanding figure.[br]Principal Honours and DistinctionsFRS.Bibliography1913, "On the removal of diffusible substances from the circulating blood by means of dialysis", Transactions of the Association of American Physiologists.Further Reading1939, Obituary Notices, Fellows of the Royal Society, London: Royal Society.1946, Biographical Memoir: John Jacob Abel. 1857–1938, Washington, DC: National Academy of Sciences.MG -
22 Braun, Karl Ferdinand
[br]b. 6 June 1850 Fulda, Hesse, Germanyd. 20 April 1918 New York City, New York, USA[br]German physicist who shared with Marconi the 1909 Nobel Prize for Physics for developments in wireless telegraphy; inventor of the cathode ray oscilloscope.[br]After obtaining degrees from the universities of Marburg and Berlin (PhD) and spending a short time as Headmaster of the Thomas School in Berlin, Braun successively held professorships in theoretical physics at the universities of Marburg (1876), Strasbourg (1880) and Karlsruhe (1883) before becoming Professor of Experimental Physics at Tübingen in 1885 and Director and Professor of Physics at Strasbourg in 1895.During this time he devised experimental apparatus to determine the dielectric constant of rock salt and developed the Braun high-tension electrometer. He also discovered that certain mineral sulphide crystals would only conduct electricity in one direction, a rectification effect that made it possible to detect and demodulate radio signals in a more reliable manner than was possible with the coherer. Primarily, however, he was concerned with improving Marconi's radio transmitter to increase its broadcasting range. By using a transmitter circuit comprising a capacitor and a spark-gap, coupled to an aerial without a spark-gap, he was able to obtain much greater oscillatory currents in the latter, and by tuning the transmitter so that the oscillations occupied only a narrow frequency band he reduced the interference with other transmitters. Other achievements include the development of a directional aerial and the first practical wavemeter, and the measurement in Strasbourg of the strength of radio waves received from the Eiffel Tower transmitter in Paris. For all this work he subsequently shared with Marconi the 1909 Nobel Prize for Physics.Around 1895 he carried out experiments using a torsion balance in order to measure the universal gravitational constant, g, but the work for which he is probably best known is the addition of deflecting plates and a fluorescent screen to the Crooke's tube in 1897 in order to study the characteristics of high-frequency currents. The oscilloscope, as it was called, was not only the basis of a now widely used and highly versatile test instrument but was the forerunner of the cathode ray tube, or CRT, used for the display of radar and television images.At the beginning of the First World War, while in New York to testify in a patent suit, he was trapped by the entry of the USA into the war and remained in Brooklyn with his son until his death.[br]Principal Honours and DistinctionsNobel Prize for Physics (jointly with Marconi) 1909.Bibliography1874, "Assymetrical conduction of certain metal sulphides", Pogg. Annal. 153:556 (provides an account of the discovery of the crystal rectifier).1897, "On a method for the demonstration and study of currents varying with time", Wiedemann's Annalen 60:552 (his description of the cathode ray oscilloscope as a measuring tool).Further ReadingK.Schlesinger \& E.G.Ramberg, 1962, "Beamdeflection and photo-devices", Proceedings of the Institute of Radio Engineers 50, 991.KF
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