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James Holmes Sturdivant
James Holmes Sturdivant (1906–1972) was a chemist who worked for several years as the main research assistant to Linus Pauling at Caltech, starting in 1927. He co-authored some seminal papers with Pauling, and was co-advisor of Robert Eugene Rundle. Personal history James Sturdivant was born in Greenville, Texas, on June 22, 1906. He got is B. A. degree at the University of Texas in 1926, his M. A. in 1927, and his Ph. D. at Caltech in 1930, advised by Pauling. By December 1954 he was living at the Athenaeum, 551 South Hill Avenue, Pasadena. Sturdivant died in Pasadena on April 21, 1972, at the age of 66, survived by his wife Arletta. Work He was instructor in Mathematics at the University of Texas from 1926 to 1927. At Caltech, he held position of Teaching Fellow (1927-1930), Research Fellow (1930-1935), Senior Fellow in Research (1935-1938), and Assistant Professor (since 1938). As a professor, he taught X-ray crystallography. One of the first results of the collaborat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linus Pauling
Linus Carl Pauling (; February 28, 1901August 19, 1994) was an American chemist, biochemist, chemical engineer, peace activist, author, and educator. He published more than 1,200 papers and books, of which about 850 dealt with scientific topics. ''New Scientist'' called him one of the 20 greatest scientists of all time, and as of 2000, he was rated the 16th most important scientist in history. For his scientific work, Pauling was awarded the Nobel Prize in Chemistry in 1954. For his peace activism, he was awarded the Nobel Peace Prize in 1962. He is one of five people to have won more than one Nobel Prize (the others being Marie Curie, John Bardeen, Frederick Sanger and Karl Barry Sharpless). Of these, he is the only person to have been awarded two unshared Nobel Prizes, and one of two people to be awarded Nobel Prizes in different fields, the other being Marie Curie. Pauling was one of the founders of the fields of quantum chemistry and molecular biology. His contributions t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Justus Von Liebig
Justus Freiherr von Liebig (12 May 1803 – 20 April 1873) was a German scientist who made major contributions to agricultural and biological chemistry, and is considered one of the principal founders of organic chemistry. As a professor at the University of Giessen, he devised the modern laboratory-oriented teaching method, and for such innovations, he is regarded as one of the greatest chemistry teachers of all time. He has been described as the "father of the fertilizer industry" for his emphasis on nitrogen and trace minerals as essential plant nutrients, and his formulation of the law of the minimum, which described how plant growth relied on the scarcest nutrient resource, rather than the total amount of resources available. He also developed a manufacturing process for beef extracts, and with his consent a company, called Liebig Extract of Meat Company, was founded to exploit the concept; it later introduced the Oxo brand beef bouillon cube. He popularized an earlier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemoglobin
Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocytes) of almost all vertebrates (the exception being the fish family Channichthyidae) as well as the tissues of some invertebrates. Hemoglobin in blood carries oxygen from the respiratory organs (''e.g.'' lungs or gills) to the rest of the body (''i.e.'' tissues). There it releases the oxygen to permit aerobic respiration to provide energy to power functions of an organism in the process called metabolism. A healthy individual human has 12to 20grams of hemoglobin in every 100mL of blood. In mammals, the chromoprotein makes up about 96% of the red blood cells' dry content (by weight), and around 35% of the total content (including water). Hemoglobin has an oxygen-binding capacity of 1.34mL O2 per gram, which increases the total blood oxygen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Monoxide
Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest molecule of the oxocarbon family. In coordination complexes the carbon monoxide ligand is called carbonyl. It is a key ingredient in many processes in industrial chemistry. The most common source of carbon monoxide is the partial combustion of carbon-containing compounds, when insufficient oxygen or heat is present to produce carbon dioxide. There are also numerous environmental and biological sources that generate and emit a significant amount of carbon monoxide. It is important in the production of many compounds, including drugs, fragrances, and fuels. Upon emission into the atmosphere, carbon monoxide affects several processes that contribute to climate change. Carbon monoxide has important biological roles across phylogenetic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Crystallographic Association
The American Crystallographic Association, Inc. (ACA) is a non-profit, scientific organization for scientists who study the structure of matter via crystallographic methodologies. Since its founding in 1949 it has amassed over 2000 members worldwide. The association meets annually in July and has several interest groups dealing with specific aspects of crystallography, including fiber diffraction, neutron scattering and powder diffraction. A quarterly magazine, called ''ACA RefleXions'', is published in addition to a scholarly journal. ''Structural Dynamics'' is a peer-reviewed, open access, online-only journal co-published by ACA and AIP Publishing. It highlights research articles on structural determination and dynamics of systems, enabled by the emerging new instruments (e.g. XFELs, high harmonic generation, ultra-short electron sources, etc.) and new experimental and theoretical methodologies. The journal is accepting short communications, topical reviews, and research papers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Physical Society
The American Physical Society (APS) is a not-for-profit membership organization of professionals in physics and related disciplines, comprising nearly fifty divisions, sections, and other units. Its mission is the advancement and diffusion of knowledge of physics. The society publishes more than a dozen scientific journals, including the prestigious '' Physical Review'' and ''Physical Review Letters'', and organizes more than twenty science meetings each year. APS is a member society of the American Institute of Physics. Since January 2021 the organization has been led by chief executive officer Jonathan Bagger. History The American Physical Society was founded on May 20, 1899, when thirty-six physicists gathered at Columbia University for that purpose. They proclaimed the mission of the new Society to be "to advance and diffuse the knowledge of physics", and in one way or another the APS has been at that task ever since. In the early years, virtually the sole activity of the AP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Chemical Society
The American Chemical Society (ACS) is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has more than 155,000 members at all degree levels and in all fields of chemistry, chemical engineering, and related fields. It is one of the world's largest scientific societies by membership. The ACS is a 501(c) organization, 501(c)(3) non-profit organization and holds a congressional charter under Title 36 of the United States Code. Its headquarters are located in Washington, D.C., and it has a large concentration of staff in Columbus, Ohio. The ACS is a leading source of scientific information through its peer-reviewed scientific journals, national conferences, and the Chemical Abstracts Service. Its publications division produces over 60 Scientific journal, scholarly journals including the prestigious ''Journal of the American Chemical Society'', as well as the weekly tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heptazine
Heptazine, or tri-''s''-triazine or cyamelurine, is a chemical compound with formula , that consist of a planar triangular core group or three fused triazine rings, with three hydrogen atoms at the corners. It is a yellow, weakly fluorescent solid with melting point over 300 °C. It is soluble in organic solvents such as acetonitrile, but is decomposed by water in the presence of light. The name "heptazine" is also used for derivative compounds, which have the three hydrogens substituted by other functional groups. Heptazine oligomers and polymers were discovered in the 19th century but their study has long been hampered by their general insolubility. They are used as flame retardants. Heptazine derivatives have been the object of interest recently for potential applications in electronics materials, explosives, and more. The synthesis of heptazine proper was reported only in 1982. History Berzelius discovered in 1815 that the ignition of mercuric thiocyanate yielded, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triazine
Triazines are a class of nitrogen-containing heterocycles. The parent molecules' molecular formula is . They exist in three isomeric forms, 1,3,5-triazines being common. Structure The triazines have planar six-membered benzene-like ring but with three carbons replaced by nitrogens. The three isomers of triazine are distinguished by the positions of their nitrogen atoms, and are referred to as 1,2,3-triazine, 1,2,4-triazine, and 1,3,5-triazine. Other aromatic nitrogen heterocycles are pyridines with one ring nitrogen atom, diazines with 2 nitrogen atoms in the ring, triazoles with 3 nitrogens in a 5 membered ring, and tetrazines with 4 ring nitrogen atoms. Uses Melamine A well known triazine is melamine (2,4,6-triamino-1,3,5-triazine). With three amino substituents, melamine is a precursor to commercial resins. Guanamines are closely related to melamine, except with one amino substituent replaced by an organic group. This difference is exploited in the use of guanamines t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydromelonic Acid
Hydromelonic acid, is an elusive chemical compound with formula or , whose molecule would consist of a heptazine molecule, with three cyanamido groups or substituted for the hydrogen atoms. The compound had not been properly isolated as of 2010, due to its tendency to polymerize. However, removal of three protons yields the melonate (formerly hydromelonate) anion , whose salts are stable and have been known since the 19th century. Removal of only two protons yields the divalent hydrogenmelonate anion . History In 1834 Justus von Liebig described the compounds that he named melamine, melam, and melon. In 1835 Leopold Gmelin prepared a potassium salt (later identified as ) by heating potassium ferrocyanide with sulfur); recognizing their connection to the compounds described by Liebig, he named the salt "hydromelonate" and the corresponding acid "hydromelonic". In the following years Liebig prepared the same salt by other methods, such as by fusing potassium thiocyanate with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyameluric Acid
Cyameluric acid or 2,5,8-trihydroxy-''s''-heptazine is a chemical compound with formula , usually described as a heptazine molecule with the hydrogen atoms replaced by hydroxyl groups ; or any of its tautomers. The substance exists as an equilibrium of 17 tautomers that easily interconvert among each other. Calculations show that the symmetric tri-oxo form (1,4,7-trihydro-2,5,8-trioxo-''s''-heptazine) is the most stable. Therefore, this compound contains amide groups rather than imidic acids. History In 1834 Justus von Liebig described the compounds that he named melamine, melam, and melon. In 1835 Leopold Gmelin prepared novel salts by heating potassium ferrocyanide with sulfur); recognizing their connection to the compounds described by Liebig, he named the salts " hydromelonates" and the corresponding acid " hydromelonic". In the following years Liebig prepared the same salts by other methods, such as by fusing potassium thiocyanate with antimony trichloride, and eventually dete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melem
In chemistry, melem is a compound with formula ; specifically, 2,5,8-triamino-heptazine or 2,5,8-triamino-tri-''s''-triazine, whose molecule can be described as that of heptazine with the three hydrogen atoms replaced by amino groups. It is a white crystalline solid. Preparation Melem can be prepared by thermal decomposition of various C−N−H compounds, such as melamine C3N3(NH2)3, dicyandiamide H4C2N4, ammonium dicyanamide NH4 (CN)2 cyanamide H2CN2, at 400 to 450 °C. Structure and properties Crystal structure Melem crystallizes in the group P21/c (No. 14), with parameters a = 739.92(1) pm, b = 865.28(3) pm, c = 1338.16(4) pm, β = 99.912(2)°, and Z = 4. The almost-planar molecules are arranged in parallel layers spaced 327 pm apart. The molecule is in the triamino form, rather than one of the possible tautomers. Thermal decomposition When heated above 560°, melem transforms into a graphite-like C−N material. Melemium cations Melem accepts up to three protons yie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
