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Crystal Engineering
Crystal engineering studies the design and synthesis of solid-state structures with desired properties through deliberate control of Intermolecular force, intermolecular interactions. It is an Interdisciplinarity, interdisciplinary academic field, bridging solid-state and supramolecular chemistry. The main engineering strategies currently in use are hydrogen bond, hydrogen- and halogen bonding and coordination bonding. These may be understood with key concepts such as the supramolecular synthon and the secondary building unit. History of term The term 'crystal engineering' was first used in 1955 by R. Pepinsky but the starting point is often credited to Gerhard Schmidt in connection with photodimerization reactions in crystalline cinnamic acids. Since this initial use, the meaning of the term has broadened considerably to include many aspects of solid state supramolecular chemistry. A useful modern definition is that provided by Gautam Radhakrishna Desiraju, Gautam Desiraju, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Intermolecular Force
An intermolecular force (IMF; also secondary force) is the force that mediates interaction between molecules, including the electromagnetic forces of attraction or repulsion which act between atoms and other types of neighbouring particles (e.g. atoms or ions). Intermolecular forces are weak relative to intramolecular forces – the forces which hold a molecule together. For example, the covalent bond, involving sharing electron pairs between atoms, is much stronger than the forces present between neighboring molecules. Both sets of forces are essential parts of force fields frequently used in molecular mechanics. The first reference to the nature of microscopic forces is found in Alexis Clairaut's work ''Théorie de la figure de la Terre,'' published in Paris in 1743. Other scientists who have contributed to the investigation of microscopic forces include: Laplace, Gauss, Maxwell, Boltzmann and Pauling. Attractive intermolecular forces are categorized into the following ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Cocrystal
In materials science (specifically crystallography), cocrystals are "solids that are crystalline, single- phase materials composed of two or more different molecular or ionic compounds generally in a stoichiometric ratio which are neither solvates nor simple salts." A broader definition is that cocrystals "consist of two or more components that form a unique crystalline structure having unique properties." Several subclassifications of cocrystals exist. Cocrystals can encompass many types of compounds, including hydrates, solvates and clathrates, which represent the basic principle of host–guest chemistry. Hundreds of examples of cocrystallization are reported annually. History The first reported cocrystal, quinhydrone, was studied by Friedrich Wöhler in 1844. Quinhydrone is a cocrystal of quinone and hydroquinone (known archaically as quinol). He found that this material was made up of a 1:1 molar combination of the components. Quinhydrone was analyzed by numerous groups ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Plasticity (physics)
In physics and materials science, plasticity (also known as plastic deformation) is the ability of a solid material to undergo permanent Deformation (engineering), deformation, a non-reversible change of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the material itself. In engineering, the transition from Elasticity (physics), elastic behavior to plastic behavior is known as Yield (engineering), yielding. Plastic deformation is observed in most materials, particularly metals, soils, Rock (geology), rocks, concrete, and foams. However, the physical mechanisms that cause plastic deformation can vary widely. At a crystalline scale, plasticity in metals is usually a consequence of dislocations. Such defects are relatively rare in most crystalline materials, but are numerous in some and part of their crystal structure; in such cases, plastic crystallinity can resul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Mechanical Properties
A material property is an intensive property of a material, i.e., a physical property or chemical property that does not depend on the amount of the material. These quantitative properties may be used as a metric by which the benefits of one material versus another can be compared, thereby aiding in materials selection. A property having a fixed value for a given material or substance is called material constant or constant of matter. (Material constants should not be confused with physical constants, that have a universal character.) A material property may also be a function of one or more independent variables, such as temperature. Materials properties often vary to some degree according to the direction in the material in which they are measured, a condition referred to as anisotropy. Materials properties that relate to different physical phenomena often behave linearly (or approximately so) in a given operating range . Modeling them as linear functions can significantly si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Complexity And Scale Of Structures Within Crystalline Materials
Complexity characterizes the behavior of a system or model whose components interact in multiple ways and follow local rules, leading to non-linearity, randomness, collective dynamics, hierarchy, and emergence. The term is generally used to characterize something with many parts where those parts interact with each other in multiple ways, culminating in a higher order of emergence greater than the sum of its parts. The study of these complex linkages at various scales is the main goal of complex systems theory. The intuitive criterion of complexity can be formulated as follows: a system would be more complex if more parts could be distinguished, and if more connections between them existed. , a number of approaches to characterizing complexity have been used in science; Zayed ''et al.'' reflect many of these. Neil Johnson states that "even among scientists, there is no unique definition of complexity – and the scientific notion has traditionally been conveyed using particul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Mechanical Properties Of Crystalline Materials
Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations of arithmetic * Mechanical energy, the sum of potential energy and kinetic energy * Mechanical system, a system that manages the power of forces and movements to accomplish a task * Mechanism (engineering), a portion of a mechanical device Other * Mechanical (character), one of several characters in Shakespeare's ''A Midsummer Night's Dream'' * A kind of typeface in the VOX-ATypI classification See also * Machine, especially in opposition to an electronic item * ''Mechanical Animals'', the third full-length studio release by Marilyn Manson * Manufactured or artificial, especially in opposition to a biological or natural component * Automation, using machine decisions and processing instead of human * Mechanization, using machine labor inst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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LRM Photodimer
LRM may refer to: * Land Reform Museum, a museum in Taipei, Taiwan * La Romana International Airport (IATA code), in the Dominican Republic * Learning relationship management, a family of learning management software * Left-to-right mark, a Unicode bidirectional formatting character * LR&M Constructions, an Australian civil engineering and construction company * IFLA Library Reference Model The IFLA Library Reference Model (IFLA LRM) is a conceptual entity–relationship model developed by the International Federation of Library Associations and Institutions (IFLA) that expresses the "logical structure of bibliographic information". ..., a conceptual entity–relationship model * ''Large Reasoning Model'', a type of artificial intelligence model, usually a neural network * ''Lance-roquettes multiple'', a variant of the M270 Multiple Launch Rocket System formerly in service with the French Army {{Disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Cambridge Crystallographic Data Centre
The Cambridge Crystallographic Data Centre (CCDC) is a Nonprofit organization, non-profit organisation based in Cambridge, England. Its primary activity is the compilation and maintenance of the Cambridge Structural Database, a database of small molecule crystal structures. They also perform analysis on the database for the benefit of the scientific community, and write and distribute computer software to allow others to do the same. History In 1962, Dr. Olga Kennard OBE FRS set up a chemical crystallography group within the Department of Chemistry, University of Cambridge. In 1965 she founded the CCDC and established the associated Cambridge Structural Database. At that time, there were only about 3,000 published X-ray crystallography, X-ray structures, and the work involved converting these into a Machine-readable data, machine-readable form. Kennard invited Frank Allen (chemist), Frank Allen to join the group, which he did in 1970, becoming Scientific Director and then Exec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Crystal Structure Prediction
Crystal structure prediction (CSP) is the calculation of the crystal structures of solids from first principles. Reliable methods of predicting the crystal structure of a compound, based only on its composition, has been a goal of the physical sciences since the 1950s. Computational methods employed include simulated annealing, evolutionary algorithms, distributed multipole analysis, random sampling, basin-hopping, data mining, density functional theory and molecular mechanics. History The crystal structures of simple ionic solids have long been rationalised in terms of Pauling's rules, first set out in 1929 by Linus Pauling. For metals and semiconductors one has different rules involving valence electron concentration. However, prediction and rationalization are rather different things. Most commonly, the term crystal structure prediction means a search for the minimum-energy arrangement of its constituent atoms (or, for molecular crystals, of its molecules) in space. The problem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Kinetics And Thermodynamics
Kinetics (, ''movement'' or ''to move'') may refer to: Science and medicine * Kinetics (physics), the study of motion and its causes ** Rigid body kinetics, the study of the motion of rigid bodies * Chemical kinetics, the study of chemical reaction rates ** Enzyme kinetics, the study of biochemical reaction rates catalysed by an enzyme *** Michaelis–Menten kinetics, the widely accepted general model of enzyme kinetics *** Goldbeter–Koshland kinetics, describe a steady-state solution for a 2-state biological system *** Langmuir–Hinshelwood kinetics ** Receptor–ligand kinetics, a branch of chemical kinetics in which the kinetic species are defined by different non-covalent bindings and/or conformations of the molecules involved, which are denoted as ''receptor(s)'' and ''ligand(s)'' *** Hill kinetics * Pharmacokinetics, the study of the processes a substance undergoes in the animal body, particularly the rates at which it is absorbed, distributed, metabolised and exc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Polymorphism (materials Science)
In crystallography, polymorphism is the phenomenon where a compound or element can crystallize into more than one crystal structure. The preceding definition has evolved over many years and is still under discussion today. Discussion of the defining characteristics of polymorphism involves distinguishing among types of transitions and structural changes occurring in polymorphism versus those in other phenomena. Overview Phase transitions (phase changes) that help describe polymorphism include polymorphic transitions as well as melting and vaporization transitions. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure." Additionally, Walter McCrone described the phases in polymorphic matter as "different in crystal structure but identical in the liquid or vapor states." McCrone also def ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Scanning Probe Microscopy
Scanning probe microscopy (SPM) is a branch of microscopy that forms images of surfaces using a physical probe that scans the specimen. SPM was founded in 1981, with the invention of the scanning tunneling microscope, an instrument for imaging surfaces at the atomic level. The first successful scanning tunneling microscope experiment was done by Gerd Binnig and Heinrich Rohrer. The key to their success was using a feedback loop to regulate gap distance between the sample and the probe. Many scanning probe microscopes can image several interactions simultaneously. The manner of using these interactions to obtain an image is generally called a mode. The resolution varies somewhat from technique to technique, but some probe techniques reach a rather impressive atomic resolution. This is largely because piezoelectricity, piezoelectric actuators can execute motions with a precision and accuracy at the atomic level or better on electronic command. This family of techniques can be cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |