Synthesis of Copper Nanoparticles by Thermal Decomposition of Anhydrous Copper Formate

Highly dispersed anhydrous copper formate obtained by cryochemical synthesis is subjected to thermal decomposition in an atmosphere of hydrogen. X-ray diffraction, PAM, UV-spectroscopy, and lowtemperature adsorption of argon show that the obtained powder contains only copper nanoparticles with a size of 50–200 nm.     

Self-immobilized catalysts for ethylene polymerization based on various phenoxyimine titanium halide complexes

The kinetic features of ethylene polymerization on ten methylalumoxane-activated self-immobilized bis(phenoxyimine) complexes of titanium chloride of various structure containing oxyallyl functional groups were studied. The catalytic activity of the systems was determined in the temperature range 20–60 °C under ethylene pressure 0.4 MPa. The positions and structures of the oxyallyl group and substituents in the phenoxy groups of the complexes substantially change the activity of the catalytic systems based on these complexes, the rate of the self-immobilization of the catalysts on the polymer, and molecular weights and molecular weight distributions of the obtained polyethylenes.     

The new frozen spin target at MAMI

The new frozen spin polarized target for experiments at the polarized beam of the real photon facility A2 of the MAMI accelerator is described. The A2-collaboration at the Mainz Microtron MAMI is measuring photon absorption cross section using circularly and linearly polarized photons up to the energy of 1.5 GeV. The photons are produced in the’ Bremsstrahlungs’ process. In the years 2005/2006 the Crystal Ball detector with its unique capability to cope with multi photon final states was set up in Mainz. Since 2010 the experimental apparatus has been completed by a polarized target. The horizontal dilution refrigerator of the Frozen-Spin Target has been constructed and is operated in close cooperation with the Joint Institute for Nuclear Research in Dubna, Russia. The system offers the opportunity to provide longitudinally and transversely polarized protons and deuteron. In this paper the operation experience of this new Frozen-Spin Target and first results from the runs in 2010 and 2011 are presented.     

On Unordered Multiplicative Partitions

In this paper, we find new identities and asymptotic formulas in the problem of multiplicative partitions, which is an analogue of the multidimensional problem of Dirichlet divisors with the condition of disorder of the factors.     

Band structure and broadband compensation of absorption by amplification in layered optical metamaterials

The frequency dependence of the gain required to compensate for absorption is determined for a layered structure consisting of alternating absorbing and amplifying layers. It is shown that the fulfillment of the same conditions is required for the existence of a band structure consisting of alternating bands allowed and forbidden for optical radiation propagation in the frequency-wave vector parametric region. Conditions are found under which the gain required for compensation is smaller than thresholds for absolute (parasitic lasing) and convective (waveguide amplification of radiation) instabilities.     

Amplification of a Raman Scattering Signal by Carbon Nanotubes

Doklady Physics - The effect of Raman scattering (RLS) signal amplification by carbon nanotubes (CNTs) was studied. Single-layered nanotubes were synthesized by the chemical vapor deposition (CVD)...     

Study of palladium nanoparticles synthesized in alkali borosilicate glass pores by the X-ray line shift method

Metallic Pd synthesized in porous glass with an average pore diameter of 7 ± 2 nm has been studied using the X-ray diffraction and X-ray line shift methods for the first time. The irregular dependence of the reflection width in X-ray patterns on the diffraction angle has been revealed. This can be caused by crystallite growth mostly in the [111] direction or by tetrahedral distortions of the fcc lattice. The shift (difference in energy) of K _α1 lines (ΔE _α1 = 19 ± 2 meV) for nanostructured Pd in comparison with the bulk material is first detected. The detected effect is considered within the assumption of the palladium electron redistribution between Pd 5s- and 4d-bands.     

Modeling oxygen Ion transport of molten oxide membranes based on V<Subscript>2</Subscript>O<Subscript>5</Subscript>

A polymer model for oxygen ion transport in molten oxide membranes (MOM) based on V₂O₅ was developed. The model adapts Wagner’s theory for molten oxides and provides an interpretation of oxygen mobility in the oxide melts. Within the framework of this model, the values of oxygen permeation fluxes through the MOM were calculated and compared with experimental data. The calculated and experimental values are of the same order of magnitude which shows an adequacy of the model. A dynamic polymer chain concept is proposed. It is shown that the transference of oxygen ions in the oxide melts may occur by a mechanism of “connection–disconnection” of the polymer chains.     

Use of shutdown of the capacitive storage in implementing electrical action on metallic shaped-charge jets

Tto improve the efficiency of electrical action on metallic shaped-charge jets, it is proposed to use shutdown of the capacitive storage at the time when the voltage on it during passage of an alternating discharge becomes zero. It has been shown that using this expedient eliminates recharging of the capacitive storage and provides better matching between the current pulse and the time of motion of various parts of the shaped-charge jet through the electrode gap. Studies have been conducted using a computational procedure in which the development of magnetohydrodynamic instability of the jet and the dispersion of its material are considered possible physical mechanisms reducing the penetration capability of shaped-charge jets under the action of high current pulses.