73 research outputs found
Spin Density Distribution in a Nitroxide Biradical Containing 13C-Enriched Acetylene Groups in the Bridge: DFT Calculations and EPR Investigation
Abstract A specially synthesized nitroxide biradical R6-13C:C-p-C6H4–C:13CR6,B3, where R6 = 1-oxyl-2,2,6,6-tetramethyl-1,2,3,6-tetrahydropyridine nitroxide,
has been studied by electron paramagnetic resonance spectroscopy, and electron-nuclear double resonance (ENDOR). Spin density distribution and hyperfine
splitting (hfs) constant on 13C atoms calculations for biradical B3 were carried out using B3LYP and PBE0 functionals and several different basis sets including N07 family and were compared with the experimental value of the hfs constant on 13C atoms, measured from ENDOR spectra of B3. The mechanism of the intramolecular
electron spin exchange in B3 biradical is discussed
Spin exchange between charged paramagnetic particles in dilute solutions
© Springer-Verlag Wien 2014. Kinetic equations for the spin density matrix which take into account binary collisions and a method of calculating the spin exchange effective radius have been generalized to the case of dilute solutions of charged paramagnetic particles. The effective radius of the spin exchange and rate constant of the bimolecular spin exchange between charged paramagnetic particles in solutions have been calculated numerically. Calculations have been performed under the assumption that the exchange interaction is isotropic and decays exponentially with the increase in the distance between radicals, and the solution has a given dielectric permittivity and Debye screening radius. Dependences of the spin exchange rate constant on the mutual diffusion coefficient, exchange and electrostatic interactions parameters have been found numerically. The theory has been applied to experimental results taken from the literature. The rate constant of the spin exchange between radicals of like charge found from the experiment and calculated within the developed theory are in good qualitative agreement
Spatial problem of water distribution in open channels
The article discusses the spatial problem of cold water movement in an open channel water distribution system through a door in a side wall. The formula for calculating the amount of cold water flowing through the channel is based on the cross-sectional area of the main channel. It is presented in terms of the velocity and depth of the water surface
Energy Release During Disk Accretion onto a Rapidly Rotating Neutron Star
The energy release L_s on the surface of a neutron star (NS) with a weak
magnetic field and the energy release L_d in the surrounding accretion disk
depend on two independent parameters that determine its state (for example,
mass M and cyclic rotation frequency f) and is proportional to the accretion
rate. We derive simple approximation formulas illustrating the dependence of
the efficiency of energy release in an extended disk and in a boundary layer
near the NS surface on the frequency and sense of rotation for various NS
equations of state. Such formulas are obtained for the quadrupole moment of a
NS, for a gap between its surface and a marginally stable orbit, for the
rotation frequency in an equatorial Keplerian orbit and in the marginally
stable circular orbit, and for the rate of NS spinup via disk accretion. In the
case of NS and disk counterrotation, the energy release during accretion can
reach . The sense of NS rotation is a factor that strongly
affects the observed ratio of nuclear energy release during bursts to
gravitational energy release between bursts in X-ray bursters. The possible
existence of binary systems with NS and disk counterrotation in the Galaxy is
discussed. Based on the static criterion for stability, we present a method of
constructing the dependence of gravitational mass M on Kerr rotation parameter
j and on total baryon mass (rest mass) m for a rigidly rotating neutron star.
We show that all global NS characteristics can be expressed in terms of the
function M(j, m) and its derivatives.Comment: 42 pages, 12 figures, to appear in Astronomy Letters, 2000, v.26,
p.69
A Model of Technical University Students’ Creative-Project Activities’ Systemic Commitment to Their Self-Development and the Experimental Verification of Its Effectiveness
The urgency of the need to develop a model of the systemic commitment of creative-project activity of technical university students to their self-development is due to the fact that the reserve possibilities of this type of teaching, research and professional activities from the perspective of the systemic commitment to self-development of the students’ competitiveness remain insufficiently investigated in the theory and practice of teacher education. In this regard, the article presents the main components of the model of systemic commitment of the creative-project activity of technical university students to their self-development, as well as the results for its implementation in practice of higher professional education. The presented components of the model in the article (objectives, contents, methods, learning and educational environment) are working for the ultimate goal − for self-development of professional creativity, self-development of the competitiveness of a student as a prospective specialist. The results of the article can be used by administrators and faculty members of higher education institutions.
DOI: 10.5901/mjss.2015.v6n2s3p12
Nodal and Periastron Precession of Inclined Orbits in the Field of a Rotating Black Hole
The inclination of low-eccentricity orbits is shown to significantly affect
the orbital parameters, in particular, the Keplerian, nodal precession, and
periastron rotation frequencies, which are interpreted in terms of observable
quantities. For the nodal precession and periastron rotation frequencies of
low-eccentricity orbits in a Kerr field, we derive a Taylor expansion in terms
of the Kerr parameter at arbitrary orbital inclinations to the black-hole spin
axis and at arbitrary radial coordinates. The particle radius, energy, and
angular momentum in the marginally stable circular orbits are calculated as
functions of the Kerr parameter and parameter in the form of Taylor
expansions in terms of to within . By analyzing our numerical
results, we give compact approximation formulas for the nodal precession
frequency of the marginally stable circular orbits at various in the entire
range of variation of Kerr parameter.Comment: 18 pages, to be published in Astronomy Letters, 2001, vol 27 (12
Spin Density Distribution in a Nitroxide Biradical Containing 13C-Enriched Acetylene Groups in the Bridge: DFT Calculations and EPR Investigation
Local structure of titanium pair centers in SrF2 crystals: EPR and ENDOR spectroscopic studies
Spin exchange between charged paramagnetic particles in dilute solutions
© Springer-Verlag Wien 2014. Kinetic equations for the spin density matrix which take into account binary collisions and a method of calculating the spin exchange effective radius have been generalized to the case of dilute solutions of charged paramagnetic particles. The effective radius of the spin exchange and rate constant of the bimolecular spin exchange between charged paramagnetic particles in solutions have been calculated numerically. Calculations have been performed under the assumption that the exchange interaction is isotropic and decays exponentially with the increase in the distance between radicals, and the solution has a given dielectric permittivity and Debye screening radius. Dependences of the spin exchange rate constant on the mutual diffusion coefficient, exchange and electrostatic interactions parameters have been found numerically. The theory has been applied to experimental results taken from the literature. The rate constant of the spin exchange between radicals of like charge found from the experiment and calculated within the developed theory are in good qualitative agreement
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