IR Spectroscopy of the inhomogeneous electronic state of lanthanum manganites

High efficiency of the approach combining the study of IR transmission and resistivity for detecting phase separation in the electron subsystem of lanthanum manganites has been demonstrated. Comparison of the magnetotransmission, magnetoresistance, and Kerr effect makes it possible to reveal the phase separation in the magnetic subsystem of manganites.     

Kinetic, optical, and elastic properties of La0.60Eu0.07Sr0.33MnO3

An experimental study is reported of the temperature dependences of the electrical resistivity and magnetoresistance, thermal and magnetothermal EMF, the Hall effect, optical reflectance, sound velocity, and internal friction of polycrystalline lanthanum manganite La_0.60Eu_0.07Sr_0.33MnO₃ carried out within the 77–430-K temperature range. Substitution of a small amount of europium for lanthanum has been found to result in a considerable decrease in the resistivity and a change in the behavior of its temperature dependence. Four characteristic temperatures at which special features are observed in the above properties have been identified. The discussion of the conduction mechanisms involved is based on the concept of mobility edge motion.     

Excitation of surface waves near the boundary of nonlinear induced inhomogeneities

Trapping the inclined beam in a surface wave with a powerful reference beam at another frequency in defocusing media with cubic or cascade quadratic nonlinearity is investigated for the first time. The results from numerical simulations of the dynamics of flat and cylindrical surface wave formation are presented. Gaussian, Hyper-Gaussian, slit, and tube reference beams are considered.     

Realization of reflectionless potentials in photonic lattices

We realize experimentally a true reflectionless potential, which facilitates nonresonant unity transmission for all incident waves and at the same time supports localized modes. We utilize arrays of evanescently coupled optical waveguides, where a particular modulation of the transverse waveguide separations provides a physical realization of reflectionless Ablowitz-Ladik soliton potentials.     

Degenerate band edges in optical fiber with multiple grating: efficient coupling to slow light

Degenerate band edges (DBEs) of a photonic bandgap have the form (ω-ω(D)) ∝k(2m) for integers m>1, with ω(D) the frequency at the band edge. We show theoretically that DBEs lead to efficient coupling into slow-light modes without a transition region, and that the field strength in the slow mode can far exceed that in the incoming medium. A method is proposed to create a DBE of arbitrary order m by coupling m optical modes with multiple superimposed gratings. The enhanced coupling near a DBE occurs because of the presence of one or more evanescent modes, which are absent at conventional quadratic band edges. We furthermore show that the coupling can be increased or suppressed by varying the number of excited evanescent waves.     

Simulation of low-sidelobe phased antenna array with circular polarization

Two shapes of antenna elements have been investigated and compared to obtain phased antenna arrays with circular polarization in the far field; a feed network providing a Chebyshev distribution of current amplitudes and uniform distribution of phases has been designed for 4 × 4 arrays; phased arrays with modified square and circular patches have been designed and compared, providing sidelobe reduction of up to ?26 dB.     

An iterative method for improving the quality of reconstruction of a three-dimensional surface

A complex image with constraints imposed on the amplitude and phase image components is processed using the Gerchberg iterative algorithm for the first time. The use of the Gerchberg iterative algorithm makes it possible to improve the quality of a three-dimensional surface profile reconstructed by the previously proposed method that is based on the multiangle projection of fringes and the joint processing of the obtained images by Fourier synthesis.     

Observation of nonlinear self-trapping in triangular photonic lattices

We experimentally study light self-trapping in triangular photonic lattices induced optically in nonlinear photorefractive crystals. We observe the formation of two-dimensional discrete and gap spatial solitons originating from the first and second bands of the linear transmission spectrum.     

Advances in the synthesis of 7-(3-cyclopentyloxy-4-methoxyphenyl)-hexahydro-3<Emphasis Type="Italic">H</Emphasis>-pyrrolizin-3-one (Pyrromilast)–a promising agent for treatment of chronic obstructive pulmonary disease

The review summarizes the known approaches to diastereo- and enantioselective synthesis of 7-(3-cyclopentyloxy-4-methoxyphenyl)hexahydro-3H-pyrrolizin-3-one (Pyrromilast), a highly active inhibitor of subtype 4B phosphodiesterase and a promising agent for treatment of chronic obstructive pulmonary disease.