Modulation of MagR magnetic properties via iron–sulfur cluster binding

Iron–sulfur clusters are essential cofactors found in all kingdoms of life and play essential roles in fundamental processes, including but not limited to respiration, photosynthesis, and nitrogen fixation. The chemistry of iron–sulfur clusters makes them ideal for sensing various redox environmental signals, while the physics of iron–sulfur clusters and its host proteins have been long overlooked. One such protein, MagR, has been proposed as a putative animal magnetoreceptor. It forms a rod-like complex with cryptochromes (Cry) and possesses intrinsic magnetic moment. However, the magnetism modulation of MagR remains unknown. Here in this study, iron–sulfur cluster binding in MagR has been characterized. Three conserved cysteines of MagR play different roles in iron–sulfur cluster binding. Two forms of iron–sulfur clusters binding have been identified in pigeon MagR and showed different magnetic properties: [3Fe–4S]-MagR appears to be superparamagnetic and has saturation magnetization at 5 K but [2Fe–2S]-MagR is paramagnetic. While at 300 K, [2Fe–2S]-MagR is diamagnetic but [3Fe–4S]-MagR is paramagnetic. Together, the different types of iron–sulfur cluster binding in MagR attribute distinguished magnetic properties, which may provide a fascinating mechanism for animals to modulate the sensitivity in magnetic sensing.

Possible structure of a local space-time of charged fermions

In the framework of general relativity, the properties of the local space-time of fermions with an electric charge are considered. It is known that the Dirac spinor field acts locally, as a contact spin-spin interaction of the gravitational and spinor fields and that may lead to some specific properties of spacetime structure. It is shown that this interaction causes real rotation of particles with spin ħ /2. It was found that this rotation is a source of intrinsic magnetic moment for electrically charged particles. As it was found, in this case the local spacetime of charged particles can have the spacetime structure of a passable «wormhole».

Hertz tensor as a basis of relativistic subelectrodynamics

The classical theory of radiation of charged particles is currently a complete theory. It has wide applications in the creation of various sources of radiation: synchrotron, undulator, etc. At the same time, the issues of radiation of the intrinsic magnetic moment of particles have not been fully investigated. In this paper, we describe a way to construct radiation fields of a point source within the framework of the Hertz tensor formalism. The derivation of the potentials and field strengths of a point radiation source is given.

Films of rhombohedral graphite as two-dimensional topological semimetals

Topologically non-trivial states appear in a number of materials ranging from spin-orbit-coupling driven topological insulators to graphene. In multivalley conductors, such as mono- and bilayer graphene, despite a zero total Chern number for the entire Brillouin zone, Berry curvature with different signs concentrated in different valleys can affect the material’s transport characteristics. Here we consider thin films of rhombohedral graphite, which appear to retain truly two-dimensional properties up to tens of layers of thickness and host two-dimensional electron states with a large Berry curvature, accompanied by a giant intrinsic magnetic moment carried by electrons. The size of Berry curvature and magnetization in the vicinity of each valley can be controlled by electrostatic gating leading to a tuneable anomalous Hall effect and a peculiar structure of the two-dimensional Landau level spectrum.

A room-temperature ferrimagnet made of metallo-proteins?

Qin et al. (A magnetic protein compass, Nature Materials 15, 217-226, 2016) claim that "MagR is the first known protein that carries an intrinsic magnetic moment at ambient temperature". We show here that the claim must, unfortunately, be fundamentally wrong.

The role of magnetic–electric coupling in exciton-coupled ECD spectra: the case of bis-phenanthrenes

The intrinsic magnetic moment of phenanthrene1Bbtransition has a strong impact on exciton-coupled CD spectra of some bis(phenanthrenes).

The ground-state magnetic moments of odd-mass Hf isotopes

In this paper the Quasiparticle-Phonon Nuclear Model (QPNM), based on QRPA (Quasiparticle Random Phase Approximation) phonons, has been utilized to investigate spin polarization effects on the groundstate magnetic properties such as intrinsic magnetic moment (g K) and effective spin gyromagnetic factor (g seff.) of odd-mass deformed 165–179Hf isotopes with K > 1/2. Investigations of the spin polarization effects of the even core on the magnetic moments show that the spin gyromagnetic factors (g s) of the nucleons in the nucleus differ noticeably from the corresponding values for free nucleons and that the spin-spin interactions play an important role in the re-normalization of g s factors of the odd-mass 165–179Hf isotopes. In addition, some theoretical predictions are presented for the magnetic moments of 165Hf, 167Hf, and 169Hf, whose ground state magnetic moments haven’t been experimentally determined yet.