Optical Configuration Effect on the Structure and Reactivity of Diastereomers Revealed by Spin Effects and Molecular Dynamics Calculations

The peculiarities of spin effects in photoinduced electron transfer (ET) in diastereomers of donor-acceptor dyads are considered in order to study the influence of chirality on reactivity. Thus, the spin selectivity—the difference between the enhancement coefficients of chemically induced dynamic nuclear polarization (CIDNP)—of the dyad’s diastereomers reflects the difference in the spin density distribution in its paramagnetic precursors that appears upon UV irradiation. In addition, the CIDNP coefficient itself has demonstrated a high sensitivity to the change of chiral centers: when one center is changed, the hyperpolarization of all polarized nuclei of the molecule is affected. The article analyzes the experimental values of spin selectivity based on CIDNP calculations and molecular dynamic modeling data in order to reveal the effect of optical configuration on the structure and reactivity of diastereomers. In this way, we succeeded in tracing the differences in dyads with L- and D-tryptophan as an electron donor. Since the replacement of L-amino acid with D-analog in specific proteins is believed to be the cause of Alzheimer’s and Parkinson’s diseases, spin effects and molecular dynamic simulation in model dyads can be a useful tool for investigating the nature of this phenomenon.

Spin and Spin-orbit Coupling Effects in Nickel-based Superalloys: A First-principles Study on Ni3Al Doped with Ta/W/Re

Heavy elements (X = Ta/W/Re) play an important role in the performance of superalloys, which enhance the strength, anti-oxidation, creep resistance, and anti-corrosiveness of alloy materials in a high-temperature environment. In the present research, the heavy element doping effects in FCC-Ni (γ) and Ni3Al (γ') systems are investigated in terms of their thermodynamic and mechanical properties, as well as electronic structures. The lattice constant, bulk modulus, elastic constant, and dopant formation energy in non-spin, spin polarized, and spin-orbit coupling (SOC) calculations are compared. The results show that the SOC effects are important in accurate electronic structure calculations for alloys with heavy elements. We find that including spin for both γ and γ' phases is necessary and sufficient for most cases, but the dopant formation energy is sensitive to different spin effects, for instance, in the absence of SOC, even spin-polarized calculations give 1% to 9% variance in the dopant formation energy in our model. Electronic structures calculations indicate that spin polarization causes a split in the metal d states, and SOC introduces a variance in the spin-up and spin-down states of the d states of heavy metals and reduces the magnetic moment of the system.

A classical relativistic hydrodynamical model for strong EM wave-spin plasma interaction

Based on the covariant Lagrangian function and Euler-Lagrange equation, a set of classical fluid equations for strong EM wave-spin plasma interaction is derived. Analysis shows that the relativistic effects may affect the interaction processes by three factors: the relativistic factor, the time component of four-spin, and the velocity-field coupling. This set of equations can be used to discuss the collective spin effects of relativistic electrons in classical regime, such as astrophysics, high-energy laser-plasma systems and so on. As an example, the spin induced ponderomotive force in the interaction of strong EM wave and magnetized plasma is investigated. Results show that the time component of four-spin, which approaches to zero in nonrelativistic situations, can increase the spin-ponderomotive force obviously in relativistic situation.

Observational Constraints on Black Hole Spin

The spin of a black hole is an important quantity to study, providing a window into the processes by which a black hole was born and grew. Furthermore, spin can be a potent energy source for powering relativistic jets and energetic particle acceleration. In this review, I describe the techniques currently used to detect and measure the spins of black holes. It is shown that: ▪ Two well-understood techniques, X-ray reflection spectroscopy and thermal continuum fitting, can be used to measure the spins of black holes that are accreting at moderate rates. There is a rich set of other electromagnetic techniques allowing us to extend spin measurements to lower accretion rates. ▪ Many accreting supermassive black holes are found to be rapidly spinning, although a population of more slowly spinning black holes emerges at masses above M > 3 × 107 M⊙ expected from recent structure formation models. ▪ Many accreting stellar-mass black holes in X-ray binary systems are rapidly spinning and must have been born in this state. ▪ The advent of gravitational wave astronomy has enabled the detection of spin effects in merging binary black holes. Most of the premerger black holes are found to be slowly spinning, a notable exception being an object that may itself be a merger product. ▪ The stark difference in spins between the black hole X-ray binary and the binary black hole populations shows that there is a diversity of formation mechanisms. Given the array of new electromagnetic and gravitational wave capabilities currently being planned, the future of black hole spin studies is bright. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Spin effects in the effective field theory approach to Post-Minkowskian conservative dynamics

Building upon the worldline effective field theory (EFT) formalism for spinning bodies developed for the Post-Newtonian regime, we generalize the EFT approach to Post-Minkowskian (PM) dynamics to include rotational degrees of freedom in a manifestly covariant framework. We introduce a systematic procedure to compute the total change in momentum and spin in the gravitational scattering of compact objects. For the special case of spins aligned with the orbital angular momentum, we show how to construct the radial action for elliptic-like orbits using the Boundary-to-Bound correspondence. As a paradigmatic example, we solve the scattering problem to next-to-leading PM order with linear and bilinear spin effects and arbitrary initial conditions, incorporating for the first time finite-size corrections. We obtain the aligned-spin radial action from the resulting scattering data, and derive the periastron advance and binding energy for circular orbits. We also provide the (square of the) center-of-mass momentum to $$ \mathcal{O}\left({G}^2\right) $$ O G 2 , which may be used to reconstruct a Hamiltonian. Our results are in perfect agreement with the existent literature, while at the same time extend the knowledge of the PM dynamics of compact binaries at quadratic order in spins.

Spin-Valued Four Bosons Electrodynamics

Electromagnetism is based on electric charge and spin. The study here corresponds to understand on spin effects at a vectorial electrodynamics. Its scenario is a non-linear abelian electromagnetism where the electric charge is transmitted through a four bosons quadruplet, constituted by the usual photon, massive photon and charged massive photons. These four bosons intermediate the charge exchange ΔQ = 0, ±1.The spin is introduced at first principles. A spintronics Lagrangian for four vector fields is performed. Considering that spin is a space-time physical entity derived from Lorentz Group, these vector fields are associated to Lorentz Group, as Lie algebra valued. Similarly to non-abelian gauge theories where Aμ≡ Aμ,ata, one introduces the relationship Aμ≡ Aμ,κλΣκλ where (Σκλ)αβ is the Lorentz Group generator. Thus, based on three fundamentals which are light invariance, electric charge conservation law and vector fields Lie algebra valued through Lorentz Group generators, one derives a spin-valued four vectorial electrodynamics. It is given by the fields quadruplet Aμ1 ≡ {Aμ, Uμ, Vμ±} where Aμ means the usual photon, Uμ a massive photon and Vμ± massive charged photons. Two novelties appear. The first one is that, new terms are developed into usual four bosons electromagnetism. They contribute to Lagrangian, equations of motion, Noether theorem. The second one is that the equations of motion derive a renormalizable spin coupling with the electric and magnetic fields.There is a spin-1 electrodynamics to be investigated. A neutral electromagnetism is mandatory to be analyzed. Something beyond dipole, quadrupole and so on. Understand the role of spin in the electrical and magnetic properties of particles. A spin vectorial expression S--> is obtained. It adds EM interactions not depending on electric charge and with spin interactions through electric dipole and magnetic moments.