Study of oxidized states in copolymers of ferrocene by the method of γ-resonance spectroscopy

Russian Chemical Bulletin -     

Black hole in an asymmetric electromagnetic field: New ponderomotive effects — Spin precession and drift

Two new ponderomotive effects in black hole physics are indicated: (i) the precession of the rotation axis of a charged black hole in an external magnetic field, (ii) the drift of a non-charged rotating hole in an asymmetric homogeneous electromagnetic field posessing a non-zero Poynting vector. The precession time for a black hole of solar mass with Q = 10^?5M in a magnetic field B ～ 10¹²G is about a year.     

The carbonylation ofα,Β′-bipiperidyl with carbon monoxide

The previously unreported N, N′-diformyl-α, Β′-bipiperidyl has been synthesized by the reaction of α,Β′-bipiperidyl with carbon monoxide under pressure.     

Shot noise in magnetic tunnel junctions: evidence for sequential tunneling

We report the experimental observation of sub-Poissonian shot noise in single magnetic tunnel junctions, indicating the importance of tunneling via impurity levels inside the tunnel barrier. For junctions with weak zero-bias anomaly in conductance, the Fano factor (normalized shot noise) depends on the magnetic configuration being enhanced for antiparallel alignment of the ferromagnetic electrodes. We propose a model of sequential tunneling through nonmagnetic and paramagnetic impurity levels inside the tunnel barrier to qualitatively explain the observations.     

Enantioselective formal total synthesis of the antitumor macrolide bryostatin 7

A new enantioselective synthesis of Masamune's AB fragment (1) for bryostatin 7 is described. Key steps in the new route include a Meerwein-Ponndorf-Verley reduction to set the O(7) stereocenter and an alkylative union between the dithiane 6 and iodide 5 to construct the C(9)-C(10) bond. Because we have previously published a synthesis of Masamune's C-ring phenyl sulfone 2, our new route to 1 constitutes a formal total synthesis of bryostatin 7; it also corrects the previously reported spectral data for 1 in CDCl3.     

Decoupling and reduction in Chern–Simons modified gravity

We show that for four-dimensional spacetimes with a non-null hypersurface orthogonal Killing vector and for a Chern–Simons (CS) background (non-dynamical) scalar field, which is constant along the Killing vector, the source-free equations of CS modified gravity decouple into their Einstein and Cotton constituents. Thus, the model supports only general relativity solutions. We also show that, when the cosmological constant vanishes and the gradient of the CS scalar field is parallel to the non-null hypersurface orthogonal Killing vector of constant length, CS modified gravity reduces to topologically massive gravity in three dimensions. Meanwhile, with the cosmological constant such a reduction requires an appropriate source term for CS modified gravity.     

Magnetocaloric effect in Pr<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ag<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>MnO<Subscript>3</Subscript> manganites

The magnetocaloric effect in alternating magnetic fields has been investigated in Pr_{1 − x} Ag _x MnO₃ manganites with x = 0.05−0.25. The stepwise reversal of the sign of the magnetocaloric effect has been revealed in a weakly doped sample (x = 0.05) at low temperatures (∼80 K). This reversal is attributed to the coexistence of the ferromagnetic and canted antiferromagnetic phases with different critical temperatures.     

Observation of a centrality-dependent dijet asymmetry in lead-lead collisions at sqrt[S(NN)] =2.76 TeV with the ATLAS detector at the LHC

By using the ATLAS detector, observations have been made of a centrality-dependent dijet asymmetry in the collisions of lead ions at the Large Hadron Collider. In a sample of lead-lead events with a per-nucleon center of mass energy of 2.76 TeV, selected with a minimum bias trigger, jets are reconstructed in fine-grained, longitudinally segmented electromagnetic and hadronic calorimeters. The transverse energies of dijets in opposite hemispheres are observed to become systematically more unbalanced with increasing event centrality leading to a large number of events which contain highly asymmetric dijets. This is the first observation of an enhancement of events with such large dijet asymmetries, not observed in proton-proton collisions, which may point to an interpretation in terms of strong jet energy loss in a hot, dense medium.     

Radiation Conditions for the Magnetic Helmholtz Equation

Mathematical Notes - It is proved that, to select a uniqueness class for the magnetic Helmholtz equation, it suffices to impose radiation conditions weaker than the Ikebe–Saito conditions....