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Excitation partial

Besides these, type-lb arrhythmia can occur at 12-30 min after the onset of ischemia with a peak at 15-20 min. These type-lb arrhythmias are either due to a partial recovery of the cell excitability (partial recovery of dU/dt and of the action potential duration), which may be ascribed to the release of catecholamines [for review see, Janse and Wit, 1989] or are due to gap junctional... [Pg.74]

A recent study of the vibrational-to-vibrational (V-V) energy transfer between highly-excited oxygen molecules and ozone combines laser-flash photolysis and chemical activation with detection by time-resolved LIF [ ]. Partial laser-flash photolysis at 532 mn of pure ozone in the Chappuis band produces translationally-... [Pg.2139]

The amount of computation for MP2 is determined by the partial transformation of the two-electron integrals, what can be done in a time proportionally to m (m is the number of basis functions), which is comparable to computations involved in one step of CID (doubly-excited configuration interaction) calculation. To save some computer time and space, the core orbitals are frequently omitted from MP calculations. For more details on perturbation theory please see A. Szabo and N. Ostlund, Modem Quantum Chemistry, Macmillan, New York, 1985. [Pg.238]

The evaluation of the various XRF measurements will be discussed for different effects in EDXRS the spectra evaluation is perfonned by different programs with varying assumptions, partially different mass attenuation coefficients are used, the calibration procedures are principally different (e.g., thin foils with given thickness, or, infinitely thick samples), measurement under atmospheric pressure or in vacuum, secondary excitation (enhancement) mainly of Al by Si radiation. [Pg.411]

The effective absorption of radiation by a gas can be increased by the addition of a sensitizer. For example, when mercuty vapour is added to silane gas, the mercury vapour absorbs radiation to form an excited atom Hg which collides with a silane molecule to lead to partial dissociation... [Pg.76]

In Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), a gaseous, solid (as fine particles), or liquid (as an aerosol) sample is directed into the center of a gaseous plasma. The sample is vaporized, atomized, and partially ionized in the plasma. Atoms and ions are excited and emit light at characteristic wavelengths in the ultraviolet or visible region of the spectrum. The emission line intensities are proportional to the concentration of each element in the sample. A grating spectrometer is used for either simultaneous or sequential multielement analysis. The concentration of each element is determined from measured intensities via calibration with standards. [Pg.48]

In addition to qualitative analysis of nearly all the elements of the periodic table, EEL spectra also enable determination of the concentration of a single element which is part of the transmitted volume and hence gives rise to a corresponding ionization edge. As in all comparable spectroscopic techniques, for quantification the net edge signal, which is related to the number N of excited atoms, must be extracted from the raw data measured. The net intensity 4 of the feth ionization shell of an individual element is directly connected to this number, N, multiplied by the partial cross-section of ionization ) and the intensity Iq of the incident electron beam, i.e. ... [Pg.65]

Electronic absorption spectra are produced when electromagnetic radiation promotes the ions from their ground state to excited states. For the lanthanides the most common of such transitions involve excited states which are either components of the ground term or else belong to excited terms which arise from the same 4f" configuration as the ground term. In either case the transitions therefore involve only a redistribution of electrons within the 4f orbitals (i.e. f—>f transitions) and so are orbitally forbidden just like d—>d transitions. In the case of the latter the rule is partially relaxed by a mechanism which depends on the effect of the crystal field in distorting the symmetry of the metal ion. However, it has already been pointed out that crystal field effects are very much smaller in the case of ions and they... [Pg.1243]

Otherwise it has been shown that the accumulation of electrolytes by many cells runs at the expense of cellular energy and is in no sense an equilibrium condition 113) and that the use of equilibrium thermodynamic equations (e.g., the Nemst-equation) is not allowed in systems with appreciable leaks which indicate a kinetic steady-state 114). In addition, a superposition of partial current-voltage curves was used to explain the excitability of biological membranes112 . In interdisciplinary research the adaptation of a successful theory developed in a neighboring discipline may be beneficial, thus an attempt will be made here, to use the mixed potential model for ion-selective membranes also in the context of biomembrane surfaces. [Pg.237]


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See also in sourсe #XX -- [ Pg.41 ]




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