Time-Dependent Resonant Tunneling in a Double-Barrier Diode Structure

The elastic moduli of bilayer graphene nanomeshes, i.e., nanomeshes of bilayer graphene, where layers at the edges of “closed” holes are coupled to each other by a continuous network of sp²-hybridized atoms, have been calculated by ab initio methods. Structures with different configurations of holes in layers with AA, AB, and 30° stackings have been studied. It has been shown that the ultimate tensile strength of the nanomeshes under consideration is higher than that of graphene nanostructures and is comparable with the ultimate tensile strength of bilayer graphene and single-layer carbon nanotubes. A possible application of such strong nanomeshes as nanocontainers for hydrogen storage and other compressed gases has been also discussed.

     

Heisenberg-limited Measurements and Sub-Planck Structures in Phase Space

It is shown how sub-Planck phase-space structures can be used to achieve Heisenberg-limited sensitivity in weak force measurements. Nonclassical states of harmonic oscillators, such as superpositions of coherent states, are shown to be useful for the measurement of weak forces that cause translations or rotations in phase space, which is done by entangling the quantum oscillator with a two-level system. This method is closely related to the Loschmidt echo techniques employed in nuclear magnetic resonance experiments. Implementations of this strategy in cavity QED and ion traps are described.     

Excitation of a waveguide transformer

Integral immitance equations for steady-state excitation of a shielded waveguide transformer with any number of arbitrarily arranged adjoint semi-infinite waveguides are derived in the general formulation. Excitation can be carried by arbitrary inner sources (extraneous electric and magnetic currents), as well as by normal modes incident from infinity. The results are extended to the case of nonideal walls for magnetodielectric and metallic inclusions. The results give a generalization of the familiar integral impedance and admittance equations for inhomogeneous waveguides.     

Numerical method for problems of diffraction on semi-infinite structures

We propose a method which transforms homogeneous integral equations into inhomogeneous ones for problems of diffraction by semi-infinite structures. New integral equations and the corresponding stationary functionals dependent on the desired scattering parameters are obtained. The consideration is performed for the open-end diffraction problem of a parallel-plate waveguide which has a rigorous solution, but the method has sufficient generality to use it for two-dimensional surface integral equations describing planar and nonplanar structures as well as for an arbitrary structure of waveguide transformer type, the solution for which can be sought in the finite domain. The method is based on field representation at the infinity as incident and scattered waves. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 3, pp. 235–245, March 2006.     

Preparation of trimethylsilyl derivatives of amino acids and peptides for peptide synthesis

Russian Chemical Bulletin -     

Investigation of the temperature dependence of the121,123Sb NQR parameters for some complexes of trivalent antimony

Conclusions The dependences of the^121,123Sb NQR frequencies on the temperature for M₂SbF₅ complexes (M=Na, Rb, Cs, CN₃H₆) and (CN₃H₆)₂ SbF₃SO₄, complexes, which display temperature ranges over which one observes a change in the character of the behavior of the asymmetry parameter of the gradient of the electric field of the antimony atoms or the spin-spin relaxation time T₂, were studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 561–565, March, 1985.     

Synthesis of N(N6)-exocyclic amino acid derivatives of 3-phenylisopropylsydnoneimine

The synthesis of N₆-amino acid derivatives of 3-phenylisopropylsydnoneimine of the carbamoyl and acyl types, which were obtained by the method of polymeric activated esters, is described. The structures of the synthesized compounds were confirmed by their IR and UV spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1335–1339, October, 1978.     

Convenient method for preparation of esters of N-carbonyl-α-amino acids

Conclusions A convenient method was proposed for obtaining the esters of N-carbonyl--amino acids, which is based on the reaction of the esters of N-trimethylsilyl--amino acids with phosgene in the presence of a tertiary amine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1682–1684, July, 1977.