September 30 Science History

- Charles Richter died.

USGS/DOI

Richter was an American seismologist who is best known for the logarithmic earthquake magnitude scale that bears his name. When an earthquake occurs, the maximum amplitude of the shake is measured on a seismometer and assigned a Richter number. A quake with a value of 5 on the Richter scale is 10 times more powerful than a quake with a value of 4.

1994 - André Michel Lwoff died.

Lwoff was a French microbiologist who was awarded a third of the 1965 Nobel Prize in Medicine for the discovery that lysogenic bacteria (bacteria that is infected by viruses) remain lysogenic in future generations. This showed the bacteriophage genetically insert themselves into the bacteria and reproducing itself. He also found a non-infecting bacteriophage that he called prophage that inhibited virus reproduction. The prophage was later found to become active when exposed to ultraviolet light which gave evidence to cancerous tumors could be caused by mutations of an inactive or dormant virus. -

1943 - Johann Deisenhofer was born.

Deisenhofer is a German biochemist who shares the 1988 Nobel Prize in Chemistry with Robert Huber and Hartmut Michel for the determination of the structure of the proteins essential for photosynthesis. They used x-ray crystallography to determine the structure of the protein and greatly increased the understanding of the mechanism of photosynthesis of plants and bacteria.

1939 - Jean-Marie Lehn was born.

Lehn is a French chemist who shares with Jean-Marie Lehn and Charles Pedersen the 1987 Nobel Prize in Chemistry for their research and development of host-guest chemistry. Host-guest chemistry is where two or more molecules/ions bond in unique ways due to their structure in other than covalent bonds. Lehn created molecules that acted as a cage molecule where a central molecule or atom would get trapped within a cavity created by the cage molecule.

1905 - Nevill Francis Mott was born.

Mott was an English physicist who shared the 1977 Nobel Prize in Physics with Philip W. Anderson and J. H. Van Vleck for their independent work with the electronic structure of magnetic and disordered systems. A disordered system is a solid with no long range order to the group of molecules that make up the solid. Glass is an example of a disordered system.

1882 - Hans Geiger was born.

Geiger was a German physicist who is best known for the invention of the Geiger counter. The Geiger counter is a particle detector that measures ionizing radiation intensity. Together with Ernest Marsden, he conducted the Gold foil experiment that first detected the presence of the atomic nucleus.

1870 - Jean Perrin was born.

Perrin was a French physicist who discovered cathode rays were actually made up of corpuscular negative charges (electrons). He is best known for verifying Einstein's theories of Brownian motion and calculating Avogadro's number, the number of molecules per mole of a gas. His work in determining the equilibrium constant of suspended solutions would earn him the 1926 Nobel Prize in Physics.

1802 - Antoine Jérôme Balard was born.

Balard was a French chemist who who isolated and identified the element bromine. He was conducting a general investigation of seawater when he found the previously unknown element in seaweed and several marine animals

1951 - Barry James Marshall was born.

Marshall is an Australian physician who shares the 2005 Nobel Prize in Medicine with J. Robin Warren for the discovery of the Helicobacter pylori bacterium. He showed this bacteria is the main cause of most peptic ulcers and not things like stress or spicy food.