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Mechanisms of Action in Bioelectromagnetics
Published in Ben Greenebaum, Frank Barnes, Bioengineering and Biophysical Aspects of Electromagnetic Fields, 2018
A magnetic moment will interact with a magnetic field, and the magnetic moments of particles or structures within atoms and molecules will interact with the internal magnetic fields due to the molecule’s electronic structure as well as with external fields. The Larmor precession of a moment in a magnetic field is a simple example. In spectroscopy, the electronic moments produce the fine structure and the nuclear moments, the hyperfine structure energy differences that produce splittings of spectroscopic lines. There is a variety of suggestions that these interactions can produce changes, whether in polarization, structure, chemical reactivity, or some other property, which can themselves affect the molecule’s interactions with its surroundings to produce downstream biological changes. Some proposals find a frequency dependence of the field effects that matches some experimental data. In the previous section, spin interactions with an external field alter radical concentrations which in turn may affect subsequent biochemistry enough to affect biological outcomes.
Symbols, Terminology, and Nomenclature
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Homopolymer - A polymer derived from one species of (real, implicit, or hypothetical) monomer. [8] Hooke's law - The statement that the ratio of stress to strain is a constant in a totally elastic medium. Horse power - A non-SI unit of energy, equal to approximately 746 W. Hubble constant - The ratio of the recessional velocity of an extragalactic object to the distance of that object. Its value is about 2 × 10-18 s-1. Huckel theory - A simple approximation for calculating the energy of conjugated molecules in which only the resonance integrals between neighboring bonds are considered. Also called CNDO method (complete neglect of differential overlap). Hume-Rothery rules - A set of empirical rules for predicting the occurrence of solid solutions in metallic systems. The rules involve size, crystal structure, and electronegativity. Hund's rules - A series of rules for predicting the sequence of energy states in atoms and molecules. One of the important results is that when two electrons exist in different orbitals, the state with their spins parallel (triplet state) lies at lower energy than the state with antiparallel spins (singlet). Hydrazines - Hydrazine (diazane), H2NNH2, and its hydrocarbyl derivatives. When one or more substituents are acyl groups, the compound is a hydrazide. [5] Hydrocarbon - A compound containing only carbon and hydrogen. [5] Hydrolysis - A reaction occurring in water in which a chemical bond is cleaved and a new bond formed with the oxygen atom of water. Hyperfine structure - Splitting of energy levels and spectral lines into several closely spaced components as a result of interaction of nuclear spin angular momentum with other angular momenta in the atom or molecule. Hysteresis* - An irreversible response of a system (parameter A) as a function of an external force (parameter F), usually symmetric with respect to the origin of the A vs. F graph after the initial application of the force. A common example is magnetic induction vs. magnetic field strength in a ferromagnet. Ideal gas law - The equation of state pV = RT, which defines an ideal gas, where p is pressure, V molar volume, T temperature, and R the molar gas constant. Ideal solution - A solution in which solvent-solvent and solventsolute interactions are identical, so that properties such as volume and enthalpy are exactly additive. Ideal solutions follow Raoult's law, which states that the vapor pressure pi of component i is pi = xipi*, where xi is the mole fraction of component i and pi* the vapor pressure of the pure substance i. Ignition temperature* - The lowest temperature at which combustion of a material will occur spontaneously under specified conditions. Sometimes called autoignition temperature, kindling point. [10] Imides - Diacyl derivatives of ammonia or primary amines, especially those cyclic compounds derived from diacids. Also used for salts having the anion RN2-. [5] Impedance (Z) - The complex representation of potential difference divided by the complex representation of current. In terms of reactance X and resistance R, the impedance is given by Z = R + iX. [1] Index of refraction (n)* - For a non-absorbing medium, the ratio of the velocity of electromagnetic radiation in vacuo to the phase velocity of radiation of a specified frequency in the medium. [1]
Effect of correlated hyperfine theory errors in the determination of rotational and vibrational transition frequencies in HD+
Published in Molecular Physics, 2022
In , the hyperfine structure arises from magnetic interactions between the proton, deuteron, electron, and molecular rotation, as well as the interaction of the deuteron electric quadrupole moment with the molecular internal electric field gradient. These interactions are described (to lowest order) by the Breit-Pauli Hamiltonian, but in practice it is more convenient to capture all interactions within an effective spin Hamiltonian that is specific to a given rovibrational state v, N. The currently most elaborate version of the effective spin Hamiltonian contains nine interaction terms [26]. The strength of each of the nine terms is characterised by a spin coefficient, (), which are obtained numerically by averaging the corresponding terms of the Breit-Pauli Hamiltonian, as well as possible high-order terms derived using the nonrelativistic quantum electrodynamics (NRQED) approach, over the rovibrational wavefunction [21,22,26].
Year-2017 nuclear quadrupole moments
Published in Molecular Physics, 2018
Einsteinium is the heaviest element with a reported Q value, 6900(800) mb for 253Es [133]. The hyperfine structure was measured using radiofrequency spectroscopy. The q was deduced from the magnetic hyperfine structure. The B was very precise, −4316.254(76) MHz.