Dephasing in disordered metals with superconductive grains

The temperature dependence of electron dephasing time tau(phi)(T) is calculated for a disordered metal with a small concentration of superconductive grains. Above the macroscopic superconducting transition line, when electrons in the metal are normal, Andreev reflection from the grains leads to a nearly temperature-independent contribution to the dephasing rate. In a broad temperature range tau(-1)(phi)(T) strongly exceeds the prediction of the classical theory of dephasing in normal disordered conductors, whereas magnetoresistance is dominated (in two dimensions) by the Maki-Tompson correction and is positive.     

Quantum percolation in granular metals

Theory of quantum corrections to conductivity of granular metal films is developed for the realistic case of large randomly distributed tunnel conductances. Quantum fluctuations of intergrain voltages (at energies E much below the bare charging energy scale E(C)) suppress the mean conductance g (E) much more strongly than its standard deviation sigma(E). At sufficiently low energies E(*) any distribution becomes broad, with sigma(E(*)) approximately g (E(*)), leading to strong local fluctuations of the tunneling density of states. The percolative nature of the metal-insulator transition is established by a combination of analytic and numerical analysis of the matrix renormalization group equations.     

Measurement of Cross Sections for Inclusive Forward Charged Hadron Production in Carbon–Carbon Collisions at Beam Energy of 19.6 GeV per Nucleon

Physics of Atomic Nuclei - The invariant cross sections for forward charged-hadron production at zero angle in carbon–carbon collisions at a beam kinetic energy of 19.6 GeV per nucleon were...     

Density of states in a mesoscopic SNS junction

The semiclassical theory of proximity effects predicts a gap E _g～?D/L ² in the excitation spectrum of a long diffusive superconductor/normal-metal/superconductor (SNS) junction. Mesoscopic fluctuations lead to anomalously localized states in the normal part of the junction.As a result, a nonzero, yet exponentially small, density of states (DOS) appears at energies below E _g. In the framework of the supermatrix nonlinear σ model, these prelocalized states are due to the instanton configurations with broken supersymmetry. The exact result for the DOS near the semiclassical threshold is found, provided the dimensionless conductance of the normal part G _N is large. The case of poorly transparent interfaces between the normal and superconductive regions is also considered. In this limit, the total number of subgap states may be large.     

Identification of pyrrolo-pyridine derivatives as novel class of antibacterials

Molecular Diversity - A series of 5-oxo-4H-pyrrolo[3,2-b]pyridine derivatives was identified as novel class of highly potent antibacterial agents during an extensive large-scale high-throughput...     

Synthesis and chemical properties of 1,2-dihydropyrrolizines (review)

Known methods for the synthesis of 1,2-dihydropyrrolizines are presented in a systematized form. Literature data on the chemical properties of 1,2-dihydropyrrolizines are summarized and correlated; and synthetic, physiologically active substances belonging to this group of compounds are examined critically.Translated from Khimiya Geterotsiklicheskikh. Soedinenii, No. 2, pp. 147–168, February, 1992.     

Synthesis of substituted 1,3-thiazinoazoles

Substituted 1,3-thiazinoazoles were obtained by treating benzimidazole-2-thione, 4,5-diphenylimidazole-2-thione, and 1,2,4-triazole-3-thione with tertiary cyanoacetylenic alcohols and their acetals in the presence of lithium hydroxide. Treatment of the 1,3-thiazinobenzimidazoles with base destroyed the thiazino ring forming benzimidazol-2-one.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1412–1415, October, 1986.     

Estimation of rotation ambiguity in multivariate curve resolution with charged particle swarm optimization (cPSO‐MCR)

Rotation ambiguity (RA) in multivariate curve resolution (MCR) is an undesirable case, when the physicochemical constraints are not sufficiently strong to provide a unique resolution of the data matrix of the mixtures into spectra and concentration profiles of individual chemical components. RA is often met in MCR of overlapped chromatographic peaks, kinetic and equilibrium data, and fluorescence two‐dimensional spectra. In case of RA, a single candidate solution has little practical value. So, the whole set of feasible solutions should be characterized somehow. It is a quite intricate task in a general case. In the present paper, a method was proposed to estimate RA with charged particle swarm optimization (cPSO), a population‐based algorithm. The criteria for updating the particles were modified, so that the swarm converged to the steady state, which spanned the set of feasible solutions. The performance of cPSO‐MCR was demonstrated on test functions, simulated datasets, and real‐world data. Good accordance of the cPSO‐MCR results with the analytical solutions (Borgen plots) was observed. cPSO‐MCR was also shown to be capable of estimating the strength of the constraints and of revealing RA in noisy data. As compared with analytical methods, cPSO‐MCR is simpler to implement, expands to more than three chemical compounds, is immune to noise, and can be easily adapted to virtually all types of constraints and objective functions (constraint based or residue based). cPSO‐MCR also provides natural visual information about the level of RA in spectra and concentration profiles, similar to the methods of two extreme solutions (e.g., MCR‐BANDS). Copyright © 2014 John Wiley & Sons, Ltd.     

New potentially tridentate amidinate ligand {o-MeOC6H4NC(Ph)N(SiMe3)}?. Synthesis and molecular structures of amidinate complexes of lithium [{o-MeOC6H4NC(Ph)N(SiMe3)}Li]2 and yttrium [{o-MeOC6H4NC(Ph)N(SiMe3)}YCl2(THF)2]2

The reaction of lithium silylamide [??o-MeOC₆H₄N(SiMe₃)}Li(OEt₂)]₂ with 2 equiv. of benzonitrile in THF at ??20 °C affords the lithium derivative of the new tridentate amidinate ligand [{o-MeOC₆H₄NC(Ph)N(SiMe₃)}Li]₂. The X-ray diffraction study showed that this complex has a dimeric structure due to the coordination of the N atoms and the ether group of one amidinate ligand to different Li atoms. The reaction of anhydrous YCl₃ with the resulting complex in THF gives the monoamidinate complex [{o-MeOC₆H₄NC(Ph)N(SiMe₃)}YCl₂(THF)₂]₂ regardless of the reagent ratio. The latter has a dimeric structure in the crystalline state as a result of the presence of two ??₂-bridging Cl atoms that link Y atoms. The ether groups of the amidinate ligands are not involved in the metal-ligand interaction.     

Explicit stabilized Runge-Kutta methods

Explicit Runge-Kutta methods with the stability domains extended along the real axis are examined. For these methods, a simple and efficient procedure for calculating the stability polynomials is proposed. Three techniques for constructing methods with given stability polynomials are considered. Methods of the second and third orders are constructed, and their accuracy as applied to solving the Prothero-Robinson equation is examined. A comparison of the above methods on some test problems is performed.