|
Klaus Bechgaard
Klaus Bechgaard (5 March 1945 – 7 March 2017) was a Danish scientist and chemist, noted for being one of the first scientists in the world to synthesize a number of organic charge transfer complexes and demonstrate their superconductivity, therefore the name Bechgaard salt. These salts all exhibit superconductivity at low temperatures. The first unconventional superconductor composed of organic material, was discovered by Bechgaard and Denis Jerome in 1979. This discovery garnered attention in the international scientific community, and for a period he was one of the most cited scientists in the field of natural sciences. He also received a nomination for the Nobel Prize in chemistry for this discovery. Research Klaus Bechgaard did research at the University of Copenhagen, where he also held a Professorship in organic chemistry until 1993. From 1993 until 2000 he was the chairman of the Department of Physics and Chemistry at Risø and in 2001 he was appointed head of the ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientist
A scientist is a person who conducts Scientific method, scientific research to advance knowledge in an Branches of science, area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engaged in the philosophical study of nature called natural philosophy, a precursor of natural science. Though Thales (circa 624-545 BC) was arguably the first scientist for describing how cosmic events may be seen as natural, not necessarily caused by gods,Frank N. Magill''The Ancient World: Dictionary of World Biography'', Volume 1 Routledge, 2003 it was not until the 19th century in science, 19th century that the term ''scientist'' came into regular use after it was coined by the theologian, philosopher, and historian of science William Whewell in 1833. In modern times, many scientists have Terminal degree, advanced degrees in an area of science and pursue careers in various Sector (economic), sectors of the economy such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condensed Matter Physics
Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases which arise from electromagnetic forces between atoms. More generally, the subject deals with "condensed" phases of matter: systems of many constituents with strong interactions between them. More exotic condensed phases include the superconducting phase exhibited by certain materials at low temperature, the ferromagnetic and antiferromagnetic phases of spins on crystal lattices of atoms, and the Bose–Einstein condensate found in ultracold atomic systems. Condensed matter physicists seek to understand the behavior of these phases by experiments to measure various material properties, and by applying the physical laws of quantum mechanics, electromagnetism, statistical mechanics, and other theories to develop mathematical models. The diversity of systems and phenomena available for study makes condensed matter phy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid-state Chemistry
Solid-state chemistry, also sometimes referred as materials chemistry, is the study of the synthesis, structure, and properties of solid phase materials, particularly, but not necessarily exclusively of, non-molecular solids. It therefore has a strong overlap with solid-state physics, mineralogy, crystallography, ceramics, metallurgy, thermodynamics, materials science and electronics with a focus on the synthesis of novel materials and their characterisation. Solids can be classified as crystalline or amorphous on basis of the nature of order present in the arrangement of their constituent particles. History Because of its direct relevance to products of commerce, solid state inorganic chemistry has been strongly driven by technology. Progress in the field has often been fueled by the demands of industry, sometimes in collaboration with academia. Applications discovered in the 20th century include zeolite and platinum-based catalysts for petroleum processing in the 1950s, high-pur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetracyanoethylene
Tetracyanoethylene (TCNE) is organic compound with the formula . It is a colorless solid, although samples are often off-white. It is an important member of the cyanocarbons. Synthesis and reactions TCNE is prepared by brominating malononitrile in the presence of potassium bromide to give the KBr-complex, and dehalogenating with copper. Oxidation of TCNE with hydrogen peroxide gives the corresponding epoxide, which has unusual properties. In the presence of base, TCNE reacts with malononitrile to give salts of pentacyanopropenide: :C2(CN)2 + CH2(CN)2 -> NC)2C-C(CN)-C(CN)2 + CN- + 2H+ Redox chemistry TCNE is an electron acceptor. Cyano groups have low energy π* orbitals, and the presence of four such groups, with their π systems (conjugated) to the central double bond, gives rise to an electrophilic alkene. TCNE is reduced at -0.27 V vs ferrocene/ferrocenium: :C2(CN)4 + e- -> 2(CN)4 Because of its ability to accept an electron, TCNE has been used to prepare numerou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrathiafulvalene
Tetrathiafulvalene is an organosulfur compound with the formula (. Studies on this heterocyclic compound contributed to the development of molecular electronics. TTF is related to the hydrocarbon fulvalene, , by replacement of four CH groups with sulfur atoms. Over 10,000 scientific publications discuss TTF and its derivatives. Preparation The high level of interest in TTFs has spawned the development of many syntheses of TTF and its analogues. Most preparations entail the coupling of cyclic building blocks such as 1,3-dithiole-2-thion or the related 1,3-dithiole-2-ones. For TTF itself, the synthesis begins with the trithiocarbonate , which is S-methylated and then reduced to give , which is treated as follows: :H2C2S2CH(SCH3) + HBF4 -> 2C2S2CH+F4- + HSCH3 :2 2C2S2CH+F4- + 2 Et3N -> (H2C2S2C)2 + 2 Et3NHBF4 Redox properties Bulk TTF itself has unremarkable electrical properties. Distinctive properties are, however, associated with salts of its oxidized derivatives, suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Van Hove Singularity
A Van Hove singularity is a singularity (non-smooth point) in the density of states (DOS) of a crystalline solid. The wavevectors at which Van Hove singularities occur are often referred to as critical points of the Brillouin zone. For three-dimensional crystals, they take the form of kinks (where the density of states is not differentiable). The most common application of the Van Hove singularity concept comes in the analysis of optical absorption spectra. The occurrence of such singularities was first analyzed by the Belgian physicist Léon Van Hove in 1953 for the case of phonon densities of states. Theory Consider a one-dimensional lattice of ''N'' particle sites, with each particle site separated by distance ''a'', for a total length of ''L'' = ''Na''. Instead of assuming that the waves in this one-dimensional box are standing waves, it is more convenient to adopt periodic boundary conditions: :k=\frac=n\frac where \lambda is wavelength, and ''n'' is an integer. (Positive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Superconductor
An organic superconductor is a synthetic organic compound that exhibits superconductivity at low temperatures. As of 2007 the highest achieved critical temperature for an organic superconductor at standard pressure is , observed in the alkali-doped fullerene RbCs2C60. In 1979 Klaus Bechgaard synthesized the first organic superconductor (TMTSF)2PF6 (the corresponding material class was named after him later) with a transition temperature of TC = 0.9 K, at an external pressure of 11 kbar. Many materials may be characterized as organic superconductors. These include the Bechgaard salts and Fabre salts which are both quasi-one-dimensional, and quasi-two-dimensional materials such as '' k-BEDT-TTF2X'' charge-transfer complex, '' λ-BETS2X'' compounds, graphite intercalation compounds and three-dimensional materials such as the alkali- doped fullerenes. Organic superconductors are of special interest not only for scientists, looking for room-temperature superconductivity and for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconventional Superconductor
Unconventional superconductors are materials that display superconductivity which does not conform to either the conventional BCS theory or Nikolay Bogolyubov's theory or its extensions. History The superconducting properties of CeCu2Si2, a type of heavy fermion material, were reported in 1979 by Frank Steglich. For a long time it was believed that CeCu2Si2 was a singlet d-wave superconductor, but since the mid 2010s, this notion has been strongly contested. In the early eighties, many more unconventional, heavy fermion superconductors were discovered, including UBe13, UPt3 and URu2Si2. In each of these materials, the anisotropic nature of the pairing was implicated by the power-law dependence of the nuclear magnetic resonance (NMR) relaxation rate and specific heat capacity on temperature. The presence of nodes in the superconducting gap of UPt3 was confirmed in 1986 from the polarization dependence of the ultrasound attenuation. The first unconventional triplet superconduct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hewlett Packard
The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components, as well as software and related services to consumers, small and medium-sized businesses ( SMBs), and large enterprises, including customers in the government, health, and education sectors. The company was founded in a one-car garage in Palo Alto by Bill Hewlett and David Packard in 1939, and initially produced a line of electronic test and measurement equipment. The HP Garage at 367 Addison Avenue is now designated an official California Historical Landmark, and is marked with a plaque calling it the "Birthplace of 'Silicon Valley'". The company won its first big contract in 1938 to provide test and measurement instruments for Walt Disney's production of the animated film ''Fantasia'', which allowed Hewlett and Packard to formally esta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EPS Europhysics Prize
The EPS CMD Europhysics Prize is awarded (currently every 2nd year) since 1975 by the Condensed Matter Division of the European Physical Society, in recognition of recent work (completed in the 5 years preceding the attribution of the award) by one or more individuals, for scientific excellence in the area of condensed matter physics. It is one of Europe’s most prestigious prizes in the field of condensed matter physics. Several laureates of the EPS CMD Europhysics Prize also received a Nobel Prize in Physics or Chemistry (Geim, Novoselov, Fert, Grünberg, Kroto, Smalley, Ertl, Bednorz, Müller, Binnig, Rohrer, von Klitzing, Alferov). Laureates SourceEuropean Physical Society* 2020: Jörg Wrachtrup - Pioneering studies on quantum coherence in solid-state systems and their applications for sensing, and, in particular, for major breakthroughs in the study of the optical and spin properties of nitrogen vacancy centers in diamond. * 2018: Lucio Braicovich and Giacomo Claudio Ghir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macintosh
The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc., Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and software engineers. The current lineup includes the MacBook Air and MacBook Pro laptops, as well as the iMac, Mac Mini, Mac Studio and Mac Pro desktops. Macs run the macOS operating system. The Macintosh 128K, first Mac was released in 1984, and was advertised with the highly-acclaimed 1984 (advertisement), "1984" ad. After a period of initial success, the Mac languished in the 1990s, until co-founder Steve Jobs returned to Apple in 1997. Jobs oversaw the release of many successful products, unveiled the modern Mac OS X, completed the Mac transition to Intel processors, 2005-06 Intel transition, and brought features from the iPhone back to the Mac. During Tim Cook's tenure as CEO, the Mac underwent a period of neglect, but was later reinv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
