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Nuclear Overhauser Effect
The nuclear Overhauser effect (NOE) is the transfer of spin polarization, nuclear spin polarization from one population of Spin (physics), spin-active nuclei (e.g. 1H, 13C, 15N etc.) to another via Relaxation (NMR), cross-relaxation. A phenomenological definition of the NOE in nuclear magnetic resonance spectroscopy (NMR) is the change in the integrated intensity (positive or negative) of one NMR resonance that occurs when another is saturated by irradiation with an Radio frequency, RF field. The change in resonance intensity of a nucleus is a consequence of the nucleus being close in space to those directly affected by the RF perturbation. The NOE is particularly important in the assignment of NMR resonances, and the elucidation and confirmation of the structures or configurations of organic and biological molecules. The 1H two-dimensional NOE spectroscopy (NOESY) experiment and its extensions are important tools to identify stereochemistry of proteins and other biomolecules in sol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spin Polarization
In particle physics, spin polarization is the degree to which the spin, i.e., the intrinsic angular momentum of elementary particles, is aligned with a given direction. This property may pertain to the spin, hence to the magnetic moment, of conduction electrons in ferromagnetic metals, such as iron, giving rise to spin-polarized currents. It may refer to (static) spin waves, preferential correlation of spin orientation with ordered lattices (semiconductors or insulators). It may also pertain to beams of particles, produced for particular aims, such as polarized neutron scattering or muon spin spectroscopy. Spin polarization of electrons or of nuclei, often called simply magnetization, is also produced by the application of a magnetic field. Curie law is used to produce an induction signal in electron spin resonance (ESR or EPR) and in nuclear magnetic resonance (NMR). Spin polarization is also important for spintronics, a branch of electronics. Magnetic semiconducto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anil Kumar (physicist)
Anil Kumar (25 June 1941 — 9 November 2024) was an Indian experimental physicist known for his work in the field of nuclear magnetic resonance spectroscopy. He was a professor at the Indian Institute of Science in Bengaluru. Kumar died in Bengaluru on 9 November 2024, at the age of 83. Early life and education Anil did his college studies at Meerut College (Agra University) from where he graduated in 1959 and completed his master's degree in 1961. From 1961 to 1964 he worked at Meerut College as a lecturer in physics, and then studied at Indian Institute of Technology Kanpur, graduating with a PhD degree in 1969 under the supervision of Prof. B. D. N. Rao. Anil moved to the United States for his post-doctoral studies: one year at Georgia Institute of Technology, Atlanta and two years at the University of North Carolina. Career Anil worked with Nobel laureate Richard R. Ernst as a research associate during 1973–76. He then worked jointly with Richard Ernst and Nobel laure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codeine Structure
Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is also commonly used as a recreational drug. It is found naturally in the sap of the opium poppy, ''Papaver somniferum''. It is typically used to treat mild to moderate degrees of pain. Greater benefit may occur when combined with paracetamol (acetaminophen) or a nonsteroidal anti-inflammatory drug (NSAID) such as aspirin or ibuprofen. Evidence does not support its use for acute cough suppression in children. In Europe, it is not recommended as a cough medicine for those under 12 years of age. It is generally taken by mouth. It typically starts working after half an hour, with maximum effect at two hours. Its effects last for about four to six hours. Codeine exhibits abuse potential similar to other opioid medications, including a risk of addiction and overdose. Common side effects include nausea, vomiting, constipation, itchiness, lightheadedness, and drowsiness. Serious sid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noesy
Two-Dimensional Nuclear Magnetic Resonance (2D NMR) is an advanced spectroscopic technique that builds upon the capabilities of one-dimensional (1D) NMR by incorporating an additional frequency dimension. This extension allows for a more comprehensive analysis of molecular structures. In 2D NMR, signals are distributed across two frequency axes, providing improved resolution and separation of overlapping peaks, particularly beneficial for studying complex molecules. This technique identifies correlations between different nuclei within a molecule, facilitating the determination of connectivity, spatial proximity, and dynamic interactions. 2D NMR encompasses a variety of experiments, including COSY (Correlation Spectroscopy), TOCSY (Total Correlation Spectroscopy), NOESY (Nuclear Overhauser Effect Spectroscopy), and HSQC (Heteronuclear Single Quantum Coherence). These techniques are indispensable in fields such as structural biology, where they are pivotal in determining protein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noe Examples
Noe may refer to: Places * Noe Valley, neighborhood in San Francisco * River Noe, tributary of the River Derwent in Derbyshire, England * Noé, Haute-Garonne, France * Noé, Ivory Coast * Noé, Yonne, France * Noe Station, in Osaka, Japan, on the Keihan Main Line * Noe Middle School, in Louisville, Kentucky * Noe Woods, University of Wisconsin–Madison Arboretum, Madison, Wisconsin People * Noe (given name), a given name in various cultures (including a list of people with the surname) * Noe (surname), a surname in various cultures (including a list of people with the surname) * Noah, a biblical figure, spelled Noé, Noè, Noë, or Noe in several languages, as well as formerly in English * NOE (rapper), American rapper Acronyms * Nuclear Overhauser effect (NOE) * Nap-of-the-earth flight * Network of Excellence * Nintendo of Europe * Neoproterozoic oxygenation event (occurred from Mid Ediacaran to Mid Cambrian) Other uses * Noé (opera), ''Noé'' (opera), by Fromenta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deuterated Chloroform
Deuterated chloroform, also known as chloroform-''d'', is the organic compound with the formula . Deuterated chloroform is a common solvent used in NMR spectroscopy. The properties of (chloroform) are virtually identical. Deuterochloroform was first made in 1935 during the years of research on deuterium. Preparation Deuterated chloroform is commercially available. It is more easily produced and less expensive than deuterated dichloromethane. Deuterochloroform is produced by the reaction of hexachloroacetone with deuterium oxide, using pyridine as a catalyst. The large difference in boiling points between the starting material and product facilitate purification by distillation. : Treating chloral with sodium deuteroxide (NaOD) gives deuterated chloroform. NMR solvent In proton NMR spectroscopy, deuterated solvent (enriched to >99% deuterium) is typically used to avoid recording a large interfering signal or signals from the proton(s) (i.e., hydrogen-1) present in the sol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyromagnetic Ratio
In physics, the gyromagnetic ratio (also sometimes known as the magnetogyric ratio in other disciplines) of a particle or system is the ratio of its magnetic moment to its angular momentum, and it is often denoted by the symbol , gamma. Its SI unit is the reciprocal second per tesla (s−1⋅T−1) or, equivalently, the coulomb per kilogram (C⋅kg−1). The -factor of a particle is a related dimensionless value of the system, derived as the ratio of its gyromagnetic ratio to that which would be classically expected from a rigid body of which the mass and charge are distributed identically, and for which total mass and charge are the same as that of the system. For a classical rotating body Consider a nonconductive charged body rotating about an axis of symmetry. According to the laws of classical physics, it has both a magnetic dipole moment due to the movement of charge and an angular momentum due to the movement of mass arising from its rotation. It can be shown that as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotational Correlation Time
Rotational correlation time (\tau_c) is the average time it takes for a molecule to rotate one radian. In solution, rotational correlation times are in the order of picoseconds. For example, the \tau_c = 1.7 ps for water, and 100 ps for a pyrroline nitroxyl radical in a DMSO-water mixture. Rotational correlation times are employed in the measurement of microviscosity (viscosity at the molecular level) and in protein characterization. Rotational correlation times may be measured by rotational (microwave), dielectric, and nuclear magnetic resonance (NMR) spectroscopy. Rotational correlation times of probe molecules in media have been measured by fluorescence lifetime or for radicals, from the linewidths of electron spin resonance Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials that have unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but the spin ...s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyromagnetic Ratio
In physics, the gyromagnetic ratio (also sometimes known as the magnetogyric ratio in other disciplines) of a particle or system is the ratio of its magnetic moment to its angular momentum, and it is often denoted by the symbol , gamma. Its SI unit is the reciprocal second per tesla (s−1⋅T−1) or, equivalently, the coulomb per kilogram (C⋅kg−1). The -factor of a particle is a related dimensionless value of the system, derived as the ratio of its gyromagnetic ratio to that which would be classically expected from a rigid body of which the mass and charge are distributed identically, and for which total mass and charge are the same as that of the system. For a classical rotating body Consider a nonconductive charged body rotating about an axis of symmetry. According to the laws of classical physics, it has both a magnetic dipole moment due to the movement of charge and an angular momentum due to the movement of mass arising from its rotation. It can be shown that as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selection Rule
In physics and chemistry, a selection rule, or transition rule, formally constrains the possible transitions of a system from one quantum state to another. Selection rules have been derived for electromagnetic transitions in molecules, in atoms, in atomic nucleus, atomic nuclei, and so on. The selection rules may differ according to the technique used to observe the transition. The selection rule also plays a role in chemical reactions, where some are formally spin-forbidden reactions, that is, reactions where the spin state changes at least once from Reagent, reactants to Product (chemistry), products. In the following, mainly atomic and molecular transitions are considered. Overview In quantum mechanics the basis for a spectroscopic selection rule is the value of the ''transition moment integral'' :m_ = \int \psi_1^* \, \mu \, \psi_2 \, \mathrm\tau, where \psi_1 and \psi_2 are the wave functions of the two states, "state 1" and "state 2", involved in the transition, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boltzmann Distribution
In statistical mechanics and mathematics, a Boltzmann distribution (also called Gibbs distribution Translated by J.B. Sykes and M.J. Kearsley. See section 28) is a probability distribution or probability measure that gives the probability that a system will be in a certain state as a function of that state's energy and the temperature of the system. The distribution is expressed in the form: :p_i \propto \exp\left(- \frac \right) where is the probability of the system being in state , is the exponential function, is the energy of that state, and a constant of the distribution is the product of the Boltzmann constant and thermodynamic temperature . The symbol \propto denotes proportionality (see for the proportionality constant). The term ''system'' here has a wide meaning; it can range from a collection of 'sufficient number' of atoms or a single atom to a macroscopic system such as a natural gas storage tank. Therefore, the Boltzmann distribution can be used to sol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
