crème de la crème

Jai Ganesh · Yesterday 16:39:42

2389) Robert S. Mulliken

Gist:

Work

The world around us consists of molecules that are composed of atoms. In Niels Bohr’s atomic model, which is based on principles of quantum physics, electrons circle the atomic nucleus in different shells that contain a fixed number of electrons. The assumption was that attractive forces between the atoms in a molecule are the result of atoms sharing electrons to fill the electron shells. Beginning in the mid-1920s, Robert Mulliken applied quantum mechanics to the development of sophisticated models for the movement of electrons within a molecule, so-called molecular orbitals.

Summary

Robert Sanderson Mulliken (born June 7, 1896, Newburyport, Mass., U.S.—died Oct. 31, 1986, Arlington, Va.) was an American chemist and physicist who received the 1966 Nobel Prize for Chemistry for “fundamental work concerning chemical bonds and the electronic structure of molecules.”

A graduate of the Massachusetts Institute of Technology, Mulliken worked, during World War I and for a few years afterward, in government chemical research. He then studied under the physicist Robert A. Millikan at the University of Chicago, receiving his Ph.D. in 1921. He taught at New York University (1926–28) and then joined the faculty of the University of Chicago (1928–85).

Mulliken began working on his theory of molecular structure in the 1920s. He theoretically systematized the electron states of molecules in terms of molecular orbitals. Departing from the idea that electron orbitals for atoms are static and that atoms combine like building blocks to form molecules, he proposed that, when molecules are formed, the atoms’ original electron configurations are changed into an overall molecular configuration. Further extending his theory, he developed (1952) a quantum-mechanical theory of the behaviour of electron orbitals as different atoms merge to form molecules.

During World War II Mulliken worked on the Plutonium Project, part of the development of the atomic bomb, at the University of Chicago. In 1955 he served as scientific attaché at the U.S. embassy in London.

Details

Robert Sanderson Mulliken ForMemRS[1] (June 7, 1896 – October 31, 1986) was an American physical chemist, primarily responsible for the early development of molecular orbital theory, i.e. the elaboration of the molecular orbital method of computing the structure of molecules. Mulliken received the Nobel Prize in Chemistry in 1966 and the Priestley Medal in 1983.[2]

Early years

Robert Mulliken was born in Newburyport, Massachusetts on June 7 1896. His father, Samuel Parsons Mulliken, was a professor of organic chemistry at the Massachusetts Institute of Technology. As a child, Robert Mulliken learned the name and botanical classification of plants and, in general, had an excellent, but selective, memory. For example, he learned German well enough to skip the course in scientific German in college, but could not remember the name of his high school German teacher. He also made the acquaintance, while still a child, of the physical chemist Arthur Amos Noyes.

Mulliken helped with some of the editorial work when his father wrote his four-volume text on organic compound identification, and thus became an expert on organic chemical nomenclature.

Education

In high school in Newburyport, Mulliken followed a scientific curriculum. He graduated in 1913 and succeeded in getting a scholarship to MIT which had earlier been won by his father. Like his father, he majored in chemistry. Already as an undergraduate, he conducted his first publishable research: on the synthesis of organic chlorides. Because he was unsure of his future direction, he included some chemical engineering courses in his curriculum and spent a summer touring chemical plants in Massachusetts and Maine. He received his B. S. degree in chemistry from MIT in 1917.

Early career

At this time, the United States had just entered World War I, and Mulliken took a position at American University in Washington, D.C., making poison gas under James B. Conant. After nine months, he was drafted into the Army's Chemical Warfare Service, but continued on the same task. His laboratory techniques left much to be desired, and he was out of service for months with burns. Later, he contracted a bad case of influenza, and was still hospitalized at war's end.

After the war, he took a job investigating the effects of zinc oxide and carbon black on rubber, but quickly decided that this was not the kind of chemistry he wanted to pursue. Hence, in 1919 he entered the Ph.D. program at the University of Chicago.

Graduate and early postdoctoral education

Mulliken got his doctorate in 1921 based on research into the separation of isotopes of mercury by evaporation, and continued in his isotope separation by this method. While at Chicago, he took a course under the Nobel Prize-winning physicist Robert A. Millikan, which exposed him to the old quantum theory. He also became interested in strange molecules after exposure to work by Hermann I. Schlesinger on diborane.

At Chicago, he had received a grant from the National Research Council (NRC) which had paid for much of his work on isotope separation. The NRC grant was extended in 1923 for two years so he could study isotope effects on band spectra of such diatomic molecules as boron nitride (BN) (comparing molecules with B10 and B11). He went to Harvard University to learn spectrographic technique from Frederick A. Saunders and quantum theory from E. C. Kemble. At the time, he was able to associate with J. Robert Oppenheimer and many future Nobel laureates, including John H. Van Vleck and Harold C. Urey. He also met John C. Slater, who had worked with Niels Bohr.

In 1925 and 1927, Mulliken traveled to Europe, working with outstanding spectroscopists and quantum theorists such as Erwin Schrödinger, Paul A. M. Dirac, Werner Heisenberg, Louis de Broglie, Max Born, and Walther Bothe (all of whom eventually received Nobel Prizes) and Friedrich Hund, who was at the time Born's assistant. They all, as well as Wolfgang Pauli, were developing the new quantum mechanics that would eventually supersede the old quantum theory. Mulliken was particularly influenced by Hund, who had been working on quantum interpretation of band spectra of diatomic molecules, the same spectra which Mulliken had investigated at Harvard. In 1927 Mulliken worked with Hund and as a result developed his molecular orbital theory, in which electrons are assigned to states that extend over an entire molecule. In consequence, molecular orbital theory was also referred to as the Hund-Mulliken theory.

Early scientific career

From 1926 to 1928, he taught in the physics department at New York University (NYU). This was his first recognition as a physicist. Though his work had been considered important by chemists, it clearly was on the borderline between the two sciences and both would claim him from this point on. Then he returned to the University of Chicago as an associate professor of physics, being promoted to full professor in 1931. He ultimately held a position jointly in both the physics and chemistry departments. At both NYU and Chicago, he continued to refine his molecular-orbital theory.

Up to this point, the primary way to calculate the electronic structure of molecules was based on a calculation by Walter Heitler and Fritz London on the hydrogen molecule (H2) in 1927. With the conception of hybridized atomic orbitals by John C. Slater and Linus Pauling, which rationalized observed molecular geometries, the method was based on the premise that the bonds in any molecule could be described in a manner similar to the bond in H2, namely, as overlapping atomic orbitals centered on the atoms involved. Since it corresponded to chemists' ideas of localized bonds between pairs of atoms, this method (called the Valence-Bond (VB) or Heitler-London-Slater-Pauling (HLSP) method), was very popular. In attempting to calculate the properties of excited states (molecules that have been excited by an energy source), the VB method does not always work well. With its description of the electron wave functions in molecules as delocalized molecular orbitals that possess the same symmetry as the molecule, Hund and Mulliken's molecular-orbital method, including contributions by John Lennard-Jones, proved to be more flexible and applicable to a vast variety of types of molecules and molecular fragments, and has eclipsed the valence-bond method. As a result of this development, he received the Nobel Prize in Chemistry in 1966.

Mulliken became a member of the National Academy of Sciences in 1936, the youngest member in the organization's history at the time. He was elected to the American Philosophical Society in 1940 and the American Academy of Arts and Sciences in 1965. He was elected a Foreign Member of the Royal Society (ForMemRs) in 1967.

Mulliken population analysis is named after him, a method of assigning charges to atoms in a molecule.

Personal life

On December 24, 1929, he married Mary Helen von Noé, daughter of Adolf Carl Noé, a geology professor at the University of Chicago. They had two daughters.

Later years

In 1934, he derived a new scale for measuring the electronegativity of elements, which he defined as the average of an atom's ionization enthalpy and electron affinity. This does not entirely correlate with the scale of Linus Pauling, but is generally in close correspondence.

In World War II, from 1942 to 1945, he directed the Information Office for the University of Chicago's Plutonium project. Afterward, he developed mathematical formulas to enable the progress of the molecular-orbital theory.

In 1952. he began to apply quantum mechanics to the analysis of the reaction between Lewis acid and base molecules. In 1961, he became Distinguished Professor of Physics and Chemistry at Florida State University, and continued in his studies of molecular structure and spectra, ranging from diatomic molecules to large complex aggregates. In 1981, Mulliken became a founding member of the World Cultural Council. In 1983, Mulliken received the Golden Plate Award of the American Academy of Achievement. He retired in 1985. His wife died in 1975.

At the age of 90, Mulliken died of congestive heart failure at his daughter's home in Arlington County, Virginia on October 31, 1986. His body was returned to Chicago for burial.

Jai Ganesh · Today 17:03:13

2390) Francis Peyton Rous

Gist:

Work

In cancer, cells grow and multiply beyond normal limits. In 1910 Peyton Rous extracted material from a cancer tumor in a hen and injected it into a healthy chicken. The chicken developed cancer, and he concluded that cells from the hen’s tumor contained an infectious substance, a virus, that transmits cancer. However, the study could not be replicated in mammals and was long overlooked. When research showed that viruses can operate by affecting the genetic material of normal germ cells, interest in Rous’ discovery was reignited.

Summary:

Peyton Rous (born October 5, 1879, Baltimore, Maryland, U.S.—died February 16, 1970, New York, New York) was an American pathologist whose discovery of cancer-inducing viruses earned him a share of the Nobel Prize for Physiology or Medicine in 1966.

Rous was educated at Johns Hopkins University, Baltimore, and at the University of Michigan. He joined the Rockefeller Institute for Medical Research (now Rockefeller University) in New York City in 1909 and remained there throughout his career. In 1911 Rous found that sarcomas in hens could be transmitted to fowl of the same inbred stock not only by grafting tumour cells but also by injecting a submicroscopic agent extractable from them; this discovery gave rise to the virus theory of cancer causation. Although his research was derided at the time, subsequent experiments vindicated his thesis, and he received belated recognition in 1966 when he was awarded (with Charles B. Huggins) the Nobel Prize.

Aside from cancer research, Rous did investigations of liver and gallbladder physiology, and he worked on the development of blood-preserving techniques that made the first blood banks possible.

Details

Francis Peyton Rous (October 5, 1879 – February 16, 1970) was an American pathologist at the Rockefeller University known for his works in oncoviruses, blood transfusion and physiology of digestion. A medical graduate from the Johns Hopkins University, he was discouraged from becoming a practicing physician due to severe tuberculosis. After three years of working as an instructor of pathology at the University of Michigan, he became dedicated researcher at the Rockefeller Institute for Medical Research for the rest of his career.

His discovery in 1911 that a chicken tumor was caused by a virus (later named Rous sarcoma virus) led to more discoveries and understanding of the role of viruses in the development of certain types of cancer. He was awarded a Nobel Prize in Physiology or Medicine for his work in 1966, 55 years after his initial discovery and he remains the oldest recipient of the Nobel Prize in Medicine or Physiology.

He and Joseph R. Turner studied methods to make use of blood types for blood transfusion. During World War I, they developed a technique for preserving blood sample by using an acid, citrate. This enabled the first practical storage of blood samples for transfusion and was introduced by Oswald H. Robertson at the front line in Belgium in 1917 as the world's first blood bank.

Awards and honors

Rous was elected a member of the United States National Academy of Sciences in 1927 and a member of the American Philosophical Society in 1939. He was elected a Foreign Member of the Royal Society (ForMemRS) in 1940. He received the Albert Lasker Award for Basic Medical Research in 1958 and the National Medal of Science in 1965. He was also member of the Royal Society of Medicine, the Royal Danish Academy of Sciences and Letters, and the Norwegian Academy of Science and Letters. He was appointed honorary fellow of the Weizmann Institute of Science and foreign correspondent of the Académie Nationale de Médecine in Paris. He also received the Kovalenko Medal of the National Academy of Sciences, the Distinguished Service Award of the American Cancer Society, the United Nations Prize for Cancer Research, and the Paul Ehrlich and Ludwig Darmstaedter Prize from the Federal Republic of Germany.

Rous shared the Nobel Prize in Physiology or Medicine in 1966 with Charles Brenton Huggins "for his discovery of tumour-inducing viruses." As early as 1926, Karl Landsteiner had nominated him and subsequently received other 16 nominations up to 1951, but was selected 55 years after his initial discovery at the age of 87, and he is recorded as the oldest recipient of the Nobel Prize in Medicine or Physiology. His remains "the longest 'incubation period' in the 110 years history of the Nobel Prizes in Physiology or Medicine."

Personal life

Rous married Marion Eckford de Kay in 1915 who survived him by fifteen years and died in 1985. He had three daughters, Marion (Marni), Ellen and Phoebe. Marni (1917–2015) was a children's book editor, and the wife of another Nobel Prize winner, Alan Lloyd Hodgkin. Phoebe married Thomas J. Wilson, director of the Harvard University Press.

In his later life he wrote biographies of Simon Flexner and Karl Landsteiner.

Death

Rous died in 1970 of abdominal cancer at the Memorial Sloan Kettering Cancer Center in New York. His wife died in 1985.

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