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Topological Index
In the fields of chemical graph theory, molecular topology, and mathematical chemistry, a topological index, also known as a connectivity index, is a type of a molecular descriptor that is calculated based on the molecular graph of a chemical compound. Topological indices are numerical parameters of a graph which characterize its topology and are usually graph invariant. Topological indices are used for example in the development of quantitative structure-activity relationships (QSARs) in which the biological activity or other properties of molecules are correlated with their chemical structure. Calculation Topological descriptors are derived from hydrogen-suppressed molecular graphs, in which the atoms are represented by vertices and the bonds by edges. The connections between the atoms can be described by various types of topological matrices (e.g., distance or adjacency matrices), which can be mathematically manipulated so as to derive a single number, usually known as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Graph Theory
Chemical graph theory is the topology branch of mathematical chemistry which applies graph theory to mathematical modelling of chemical phenomena. The pioneers of chemical graph theory are Alexandru Balaban, Ante Graovac, Iván Gutman, Haruo Hosoya, Milan Randić and Nenad Trinajstić (also Harry Wiener and others). In 1988, it was reported that several hundred researchers worked in this area, producing about 500 articles annually. A number of monographs have been written in the area, including the two-volume comprehensive text by Trinajstić, ''Chemical Graph Theory'', that summarized the field up to mid-1980s. The adherents of the theory maintain that the properties of a chemical graph (i.e., a graph-theoretical representation of a molecule) give valuable insights into the chemical phenomena. Others contend that graphs play only a fringe role in chemical research.D.H. Rouvray, "Combinatorics in Chemistry", pp. 1955-1982, in: Ronald Graham, Martin Grötschel, László Lovász ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyper-Wiener Index
In chemical graph theory, the hyper-Wiener index or hyper-Wiener number is a topological index of a molecule, used in biochemistry. The hyper-Wiener index is a generalization introduced by Milan Randić of the concept of the Wiener index, introduced by Harry Wiener. The hyper-Wiener index of a connected graph ''G'' is defined by : WW(G)=\frac 1 2 \sum_(d(u,v)+d^2(u,v)), where ''d''(''u'',''v'') is the distance between vertex ''u'' and ''v''. Hyper-Wiener index as topological index assigned to ''G'' = (''V'',''E'') is based on the distance function which is invariant under the action of the automorphism group of ''G''. Hyper-Wiener index can be used for the representation of computer networks and enhancing lattice hardware security. Hyper-Wiener indices used to limit the structure of a particle into a solitary number which signifies the sub-atomic stretching and electronic structures. Example One-pentagonal carbon nanocone which is an infinite symmetric grap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drug Development
Drug development is the process of bringing a new pharmaceutical drug to the market once a lead compound has been identified through the process of drug discovery. It includes preclinical research on microorganisms and animals, filing for regulatory status, such as via the United States Food and Drug Administration for an investigational new drug to initiate clinical trials on humans, and may include the step of obtaining regulatory approval with a new drug application to market the drug. The entire process – from concept through preclinical testing in the laboratory to clinical trial development, including Phase I–III trials – to approved vaccine or drug typically takes more than a decade. New chemical entity development Broadly, the process of drug development can be divided into preclinical and clinical work. Pre-clinical New chemical entities (NCEs, also known as new molecular entities or NMEs) are compounds that emerge from the process of drug discovery. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drug Discovery
In the fields of medicine, biotechnology and pharmacology, drug discovery is the process by which new candidate medications are discovered. Historically, drugs were discovered by identifying the active ingredient from traditional remedies or by serendipitous discovery, as with penicillin. More recently, chemical libraries of synthetic small molecules, natural products or extracts were screened in intact cells or whole organisms to identify substances that had a desirable therapeutic effect in a process known as classical pharmacology. After sequencing of the human genome allowed rapid cloning and synthesis of large quantities of purified proteins, it has become common practice to use high throughput screening of large compounds libraries against isolated biological targets which are hypothesized to be disease-modifying in a process known as reverse pharmacology. Hits from these screens are then tested in cells and then in animals for efficacy. Modern drug discovery inv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Risk Assessment
Broadly speaking, a risk assessment is the combined effort of: # identifying and analyzing potential (future) events that may negatively impact individuals, assets, and/or the environment (i.e. hazard analysis); and # making judgments "on the tolerability of the risk on the basis of a risk analysis" while considering influencing factors (i.e. risk evaluation). Put in simpler terms, a risk assessment determines possible mishaps, their likelihood and consequences, and the tolerances for such events. The results of this process may be expressed in a quantitative or qualitative fashion. Risk assessment is an inherent part of a broader risk management strategy to help reduce any potential risk-related consequences. Need Individual risk assessment Risk assessment are done in individual cases, including patient and physician interactions. Individual judgements or assessments of risk may be affected by psychological, ideological, religious or otherwise subjective factors, which im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Property
Molecular properties include the chemical properties, physical properties, and structural properties of molecules, including drugs. Molecular properties typically do not include pharmacological or biological properties of a chemical compound. See also * Biological activity * Chemical property * Chemical structure * Lipinski's rule of five Lipinski's rule of five, also known as Pfizer's rule of five or simply the rule of five (RO5), is a rule of thumb to evaluate druglikeness or determine if a chemical compound with a certain pharmacological or biological activity has chemical pro ..., describing molecular properties of drugs * Physical property * QSAR, quantitative structure-activity relationship References Physical quantities Molecules {{chem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Geometry
Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometrical parameters that determine the position of each atom. Molecular geometry influences several properties of a substance including its reactivity, polarity, phase of matter, color, magnetism and biological activity. The angles between bonds that an atom forms depend only weakly on the rest of molecule, i.e. they can be understood as approximately local and hence transferable properties. Determination The molecular geometry can be determined by various spectroscopic methods and diffraction methods. IR, microwave and Raman spectroscopy can give information about the molecule geometry from the details of the vibrational and rotational absorbance detected by these techniques. X-ray crystallography, neutron diffraction and electron diffraction can give molecu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Activity
In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or pharmacophore but can be modified by the other constituents. Among the various properties of chemical compounds, pharmacological/biological activity plays a crucial role since it suggests uses of the compounds in the medical applications. However, chemical compounds may show some adverse and toxic effects which may prevent their use in medical practice. Activity is generally dosage-dependent. Further, it is common to have effects ranging from beneficial to adverse for one substance when going from low to high doses. Activity depends critically on fulfillment of the ADME criteria. To be an effective drug, a compound not only must be active against a target, but also possess the appropriate ADME (Absorption, Distribution, Metabolism, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Model
A statistical model is a mathematical model that embodies a set of statistical assumptions concerning the generation of sample data (and similar data from a larger population). A statistical model represents, often in considerably idealized form, the data-generating process. A statistical model is usually specified as a mathematical relationship between one or more random variables and other non-random variables. As such, a statistical model is "a formal representation of a theory" ( Herman Adèr quoting Kenneth Bollen). All statistical hypothesis tests and all statistical estimators are derived via statistical models. More generally, statistical models are part of the foundation of statistical inference. Introduction Informally, a statistical model can be thought of as a statistical assumption (or set of statistical assumptions) with a certain property: that the assumption allows us to calculate the probability of any event. As an example, consider a pair of ordinary six ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gutman Index
Gutman is a surname. Notable people with the surname include: * Alberto Gutman (born 1959), American politician * Albin Gutman (born 1947), Slovene general * Alexander Gutman (born 1945), Russian film director * Amy Gutman (born 1960), American novelist * Anthony Gutman, British banker * Dan Gutman (born 1955), American author * Daniel Gutman (1901-1993), American lawyer, state senator, state assemblyman, president justice of the municipal court, and law school dean. * Gloria M Gutman (born 1939), Canadian gerontologist * Herbert Gutman (1928–1985), American labor historian and scholar of slavery * Howard W. Gutman (born 1956), American ambassador * Huck Gutman (born c.1944), American academic and political adviser * Hugo Gutmann (1880–1962) German-Jewish veteran of first World War, famously known as Adolf Hitler's superior officer. * Israel Gutman (1923–2013), Israeli historian * Iván Gutman (born 1947), Serbian chemist and mathematician * Jacob C. Gutman (1890–1982 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Padmakar–Ivan Index
In chemical graph theory, the Padmakar–Ivan (PI) index is a topological index of a molecule, used in biochemistry. The Padmakar–Ivan index is a generalization introduced by Padmakar V. Khadikar and Iván Gutman of the concept of the Wiener index, introduced by Harry Wiener. The Padmakar–Ivan index of a graph ''G'' is the sum over all edges ''uv'' of ''G'' of number of edges which are not equidistant from ''u'' and ''v''. Let ''G'' be a graph and ''e'' = ''uv'' an edge of ''G''. Here n_(e\mid G) denotes the number of edges lying closer to the vertex ''u'' than the vertex ''v'', and n_(e\mid G) is the number of edges lying closer to the vertex ''v'' than the vertex ''u''. The Padmakar–Ivan index of a graph ''G'' is defined as : \operatorname(G)=\sum_ _(e\mid G) + n_(e\mid G) The PI index is very important in the study of quantitative structure–activity relationship for the classification models used in the chemical, biological sciences, engineering, and nano ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
