Polymer Nanocomposites Exploited Under The Arctic Conditions

Several technologies of the preparation of nanocomposites based on ultra-high-molecular-weight polyethylene were developed. The first technology is based on mechanical activation of layered silicates with surfactant before addition into polymer matrix. The second technology represents mixing of ultra-high-molecular-weight polyethylene with nanoparticles by joint mechanical activation in a planetary mill. The third technology is based on mixing of ultra-high-molecular-weight polyethylene with nanoparticles in liquid media under continuous ultrasonic treatment. Common features of these technologies are reaching of filler uniform distribution in a polymer matrix and significant improvement in the mechanical properties. Also, supramolecular structure of the composites was studied

Influence of Carbon Fibers on Structure and Properties of Polytetrafluoroethylene

In this paper, we studied the effect of carbon fibers on the performance properties of polymer composites based on polytetrafluoroethylene. It was shown that the introduction of PTFE carbon fibers significantly improved tribological and mechanical properties of the composite. The correlation between the performance properties and supramolecular structure was found. Initial lamellar structure of the polymer became less in size without significant changes in morphology when filled. Such process was accompanied by the increase of crystalline regions number and the crystallinity degree of composite. Structural studies have shown that materials with more densely packed and highly crystalline structure have increased mechanical and tribological properties. The developed materials can be used in friction units of machines and devices, where the use of lubricants is not acceptable or restricted

X-ray spectroscopy studies of the electronic structure and band-structure calculations of cubic TaCxN1-x carbonitrides

The electronic structure of almost stoichiometric cubic (NaCl structure) tantalum carbonitrides TaCxN₁₋x synthesized under high pressure-high temperature conditions (7-10 GPa and 2100-2400°C) was studied employing X-ray photoelectron spectroscopy (XPS), Xray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS). The XPS valence-band and core-level spectra, the XES Ta Lβ ₅, C Kα and N Kα bands (reflecting energy distributions of mainly the Ta 5d-, C 2p- and N 2p-like states, respectively), as well as the XAS Ta LIII edges (unoccupied Ta d-like states) were derived and compared on a common energy scale for the compounds TaC₀.₉₈, TaC₀.₅₂N₀.₄₉ and TaN₀.₉₇ obtained under the mentioned high pressure-high temperature conditions. To investigate the influence of substitution of carbon atoms by nitrogen in the cubic TaCxN₁₋x system, the cluster self-consistent calculations of the electron density of states for cubic TaC, TaC₀.₅N₀.₅ and TaN compounds were carried out with the FEFF8 code. In the present work a rather good agreement of the experimental and theoretical results for the electronic structure of the TaCxN₁₋x system under consideration was obtained

Joule heating effects on quartz particle melting in high-temperature silicate melt

This work is mostly focused on the melting process model simulation of quartz particles having the radius within the range of 10{-6}-10{-3} m. The melting process is simulated accounting for the heat generation at an electric current passage through a quartz particle

Forinjector VEPP-5 klystron gallery control system

VEPP-5 forinjector klystron gallery (KG) is a large electrophysical installation that includes main part of forinjector RF-system supply, synchrosystem, klystron units. This paper presents the control system (CS) of it. CS is based on the "standard" 3-level model [1]. Details of its realization reflects KG functional requirements and experience accumulated in BINP, as well as financial and technical abilities

Status of the Lake Baikal Experiment

We review the present status of the Baikal Underwater Neutrino Experiment and report on neutrino events recorded with the detector stages NT-36 and NT-96.Comment: 5 pages, 4 PostScript figures, uses here.sty and mine.sty, submitted to the Proc. of 5th Int. Workshop on Topics in Astroparticle and Underground Physics (LNGS INFN, Assergi, September 7-11, 1997

Polynomial Solution of Non-Central Potentials

We show that the exact energy eigenvalues and eigenfunctions of the Schrodinger equation for charged particles moving in certain class of non-central potentials can be easily calculated analytically in a simple and elegant manner by using Nikiforov and Uvarov (NU) method. We discuss the generalized Coulomb and harmonic oscillator systems. We study the Hartmann Coulomb and the ring-shaped and compound Coulomb plus Aharanov-Bohm potentials as special cases. The results are in exact agreement with other methods.Comment: 18 page

7 GHz pulsed magnicon amplifier

The work on creation of high-power microwave amplifiers with circular deflection of an electron beam has been carried out at INP since 1967. In the latest set of experiments on 7 GHz magnicon almost all design parameters have been achieved: the output power of 55 MW, efficiency of 56 %, and gain of 72 dB. Experimental data are in an excellent agreement with simulation results obtained by the special magnicon computer codes. Achieved results allow us to consider a magnicon as an alternative power source for linear colliders applications

The Baikal Deep Underwater Neutrino Experiment: Results, Status, Future

We review the present status of the Baikal Underwater Neutrino Experiment and present results obtained with the various stages of the stepwise increasing detector: NT-36 (1993-95), NT-72 (1995-96) and NT-96 (1996-97). Results cover atmospheric muons, first clear neutrino events, search for neutrinos from WIMP annihilation in the center of the Earth, search for magnetic monopoles, and -- far from astroparticle physics -- limnology.Comment: Talk given at the Int. School on Nuclear Physics, Erice, Sept.199