Dynamics of Explosive Volcano Degassing

We construct a one-dimensional nonstationary model of explosive degassing for a volcano with plugged conduit. The motion of the plug is assumed to be due to the presence of a gas cavity under it into which a gas flows from the underlying magma, which increases the pressure. We show that periodic explosions of gas occur in the system that are separated by long quiescent stages, which agrees with the data of field observations.     

Effect of the nature of the anion on the composition and structure of cobalt complex with monoethanolamine

A number of products formed in reactions of cobalt(II) salts with monoethanolamine (HEtm) in a neutral medium were synthesized and studied. X-Ray diffraction study showed that the nitrate and acetate form the dimers [Co(HEtm)₃][Co(Etm)₃](NO₃)₃ and [Co(HEtm)₃][Co(Etm)₃](CH₃COO)₃ · 8H₂O, respectively. In chloride solutions, cobalt is partially oxidized to give the trinuclear complex [Co^II{Co^III(Etm)₃}₂]Cl₃ · H₂Etm · 2H₂O. The reaction of the chelate [Co(Etm)₃] · 3H₂O with nitric acid is accompanied by complete protonation of the coordinated aminoethanolate ions, and the reaction with formic acid involves complete replacement of the coordinated ligand by acid residue anions and water molecules to give the coordination polymer {Co₂(μ-HCOO)₄(H₂O)₄} _n .     

Resonant Raman scattering in ultrafine CdSxSe1−x colloidal particles

Vibrational spectra of ultrafine (～1.8 nm) CdS _x Se_1?x colloidal nanoparticles (NPs) are studied by resonant Raman scattering (RRS). The detected difference of the shape and spectral position of the longitudinal optical vibration band in comparison with the spectrum of slightly larger NPs (≥ 2 nm) is explained by the dominance of surface atoms as their fraction increases above 50%. The correlation of experimental results with ab initio calculated vibrational spectra and with vibration anharmonicity enhancement as the NP size decreases is discussed.     

Dynamics of nonself-similar solutions of the Dawson equation

We study the dynamics of nonself-similar solutions of the Cauchy problem for a stochastic partial differential Itô equation of the parabolic type with linear principal part and with the diffusion coefficient that is exponential function whose exponent is larger than zero, but is less than 1. The equations of such a type are named the Dawson equations. It is proved that the solution that is of a nonself-similar form and is generated by a finite initial function behaves itself in the course of time analogously to a self-similar solution.     

Copper coated nickel foam as current collector for H2S-containing syngas solid oxide fuel cells

Copper coated nickel foam with Cu/Ni ratio of 2.5 was fabricated using electrochemical plating and characterized using XRD, SEM, EDS and Van der Pauw four point conductivity measurements. Copper coated nickel foam exhibited good stability of electronic conductivity and mechanical strength during more than 150 h exposure to 500 ppm H₂S-containing syngas at 750 °C. In contrast, uncoated nickel foam readily underwent severe carbon deposition and brittle fracture resulting in dramatic increase of electronic resistance under the same testing conditions. Copper coated nickel foam is a promising current collector for H₂S-containing syngas solid oxide fuel cells (SOFCs).     

Monte Carlo test of the Goldstone mode singularity in 3D XY model

Monte Carlo simulations of magnetization and susceptibility in the 3D XY model are performed for system sizes up to L=384 (significantly exceeding the largest size L=160 considered in work published previously), and fields h ≥ 0.0003125 at two different coupling constants β=0.5, and β=0.55 in the ordered phase. We examine the prediction of the standard theory that the longitudinal susceptibility χ_∥ has a Goldstone mode singularity such that χ_∥ ∝h^-1/2 holds when h↦0. Most of our results, however, support another theoretical prediction that the singularity is of a more general form χ_∥ ∝h^ρ-1, where 1/2<ρ<1 is a universal exponent related to the ∼h^ρ variation of the magnetization.     

Neutral decays of the η-meson

The partial widths of η-meson decays η→2γ, η→3π⁰ and η→π⁰γγ have been measured in a high accuracy experiment made at the IHEP accelerator with the hodoscope electromagnetic spectrometer GAMS-2000. An upper limit has been determined for the 3γ channel. The Dalitz plot of the η decay into 3π⁰ shows that the matrix element does not depend on the pion energy.     

Lifting-line theory of swept wings based on the full potential theory

The asymptotic theory of high-aspect-ratio transonic swept wings of Refs. [2–5] is extended to irrotational compressible flows based on equations of the full-potential theory. The formulation allows for imbedded supercritical flows with shocks; the results are applicable to oblique wings, swept-back as well as swept-forward wings, but restricted to planforms with centerlines composed of straight segments. The free-stream velocity is assumed to remain below the sonic speed. For a wing geometry generated from a single airfoil shape, the reduced system of 2-D equations admits solutions with similarity structures, permitting the problem to be solved only once for all span stations. The application of the theory is expected to lead to a substantial improvement over the earlier analysis of transonic swept wings based on the small-disturbance theory, concerning the accurate determination of inviscid drag and lift. The study provides also a basis for examining the influence of the trailing vortex sheet geometry, which are incompletely accounted for in current 3-D computer programs.

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Zusammenfassung Die asymptotische Theorie von transonischen gepfeilten Flügeln mit hohem Seitenverhältnis (Ref. [2]–[5]) wird erweitert auf wirbelfreie kompressible Strömungen mit Verwendung der Gleichungen der vollständigen Potentialtheorie. Die Formulierung gestattet die Behandlung von eingeschlossenen superkritischen Gebieten mit Stößen; die Resultate sind für schiefe, rückwärts- und vorwärtsgepfeilte Flügel verwendbar, sind aber auf Flügelgrundrisse mit streckenweise geraden Mittellinien beschränkt. Die Anströmgeschwindigkeit liegt immer unterhalb der Schallgeschwindigkeit. Für Flügelgeometrien die durch ein einziges Profil erzeugt werden, gestattet ein reduziertes System in zwei Dimensionen Lösungen mit einer Ähnlichkeits-Struktur, die eine Lösung für alle Stationen entlang der Spannweite liefert. Betreffend der genauen Bestimmung von Widerstand und Auftrieb wird von der Theorie eine wesentliche Verbesserung gegenüber der Analyse von Pfeilflügeln erwartet, die auf der Theorie von kleinen Störungen basiert. Die Arbeit gibt auch die Grundlage für eine Untersuchung des Einflusses von abgehenden Wirbeln, die in bisherigen dreidimensionalen Computer-Programmen nur unvollständig berücksichtigt worden sind.

     

Luminescent Properties of a Composite of Acrylic Polymers Doped with Eu(III) Complex for Ink-Jet Printing Applications

We present a composite material based on polymer matrices doped with a new europium(III) complex exhibiting high quantum yield. The Eu(III) complex was introduced into two types of polymer matrices. We investigate the concentration influence of the complex embedded into polymers on luminescent properties of the composite material. This Eu(III) complex proved to be highly dispersible in polymers and compatible with ink-jet technology.