Cotton fibre humidification at cotton ginneries

A novel humidifier has been designed and developed forimproving the quality of cotton lint, by providing more efficientand qualitative humidification of cotton lint before pressing.Existing methods of cotton lint humidification have not beenfound effective enough, do not provide required increase inmoisture content and have technological and structuraldisadvantages. The proposed humidifier ensures the gain ofmoisture content up to 1.6 % and its high uniformity

Holographic Structure Transfer from Dichromated Gelatin Layers to a Polymethylmethacrylate Substrate

It is shown that the formation of a holographic structure on the polymethylmethacrylate (PMMA) surface is based on the use of the destructive effect of short-wave UV radiation with a wavelength less than 270 nm through windows previously formed in a thin layer of dichromated gelatin (DCG) covering the substrate. The optimization of the PMMA surface treatment by isopropanol and methylisobutyl ketone (MIBK) developers was made, which allowed creating on the PMMA substrates relief-phase holographic gratings with the high diffraction efficiency (DE) of about 25% and maximum depth of the surface relief of the order of 1 μm. Keywords: holographic gratings, surface relief, UV radiation, dichromated gelatin, polymethylmethacrylate, methylisobutyl ketone (MIBK)

The Early Evolution of Massive Stars: Radio Recombination Line Spectra

Velocity shifts and differential broadening of radio recombination lines are used to estimate the densities and velocities of the ionized gas in several hypercompact and ultracompact HII regions. These small HII regions are thought to be at their earliest evolutionary phase and associated with the youngest massive stars. The observations suggest that these HII regions are characterized by high densities, supersonic flows and steep density gradients, consistent with accretion and outflows that would be associated with the formation of massive stars.Comment: ApJ in pres

Nonlinear acousto-electric transport in a two-dimensional electron system

We study both theoretically and experimentally the nonlinear interaction between an intense surface acoustic wave and a two-dimensional electron plasma in semiconductor-piezocrystal hybrid structures. The experiments on hybrid systems exhibit strongly nonlinear acousto-electric effects. The plasma turns into moving electron stripes, the acousto-electric current reaches its maximum, and the sound absorption strongly decreases. To describe the nonlinear phenomena, we develop a coupled-amplitude method for a two-dimensional system in the strongly nonlinear regime of interaction. At low electron densities the absorption coefficient decreases with increasing sound intensity, whereas at high electron density the absorption coefficient is not a monotonous function of the sound intensity. High-harmonic generation coefficients as a function of the sound intensity have a nontrivial behavior. Theory and experiment are found to be in a good agreement.Comment: 27 pages, 6 figure

Polymerization of Lactic Acid Using Microwave and Conventional Heating

The polymerization of lactic acid (LA) has been investigated by two methods: conventional heating and under microwave irradiation. The reactions of polymerization have been carried out in two stages: at the beginning water is removed and oligomer is obtained; then, the catalysts/co-catalysts are added and reactions are carried out. Tin octoate, toluene sulfonic acid, 2-aminopropanoic acid (alanine) have been investigated as polymerization catalysts and the derivatives of 2,4,6,8- tetramethilol -2,4,6,8- tetraazabicyclo[3.3.0]octane -3,7-dion (Tetraol), comprising atoms of Mg, Zn, Al have been synthesized for the first time. The structure of the synthesized catalyst has been investigated using the method of IR, {1}H NMR. It has been shown that the process of obtaining polylactic acid (PLA) by microwave irradiation proceeds hundreds of times faster. PLA samples synthesized by this method have the same optical characteristics as the PLA obtained by conventional heating

3-He in the Milky Way Interstellar Medium: Ionization Structure

The cosmic abundance of the 3-He isotope has important implications for many fields of astrophysics. We are using the 8.665 GHz hyperfine transition of 3-He+ to determine the 3-He/H abundance in Milky Way HII regions and planetary nebulae. This is one in a series of papers in which we discuss issues involved in deriving accurate 3-He/H abundance ratios from the available measurements. Here we describe the ionization correction we use to convert the 3-He+/H+ abundance, y3+, to the 3-He/H abundance, y3. In principle the nebular ionization structure can significantly influence the y3 derived for individual sources. We find that in general there is insufficient information available to make a detailed ionization correction. Here we make a simple correction and assess its validity. The correction is based on radio recombination line measurements of H+ and 4-He+, together with simple core-halo source models. We use these models to establish criteria that allow us to identify sources that can be accurately corrected for ionization and those that cannot. We argue that this effect cannot be very large for most of the sources in our observational sample. For a wide range of models of nebular ionization structure we find that the ionization correction factor varies from 1 to 1.8. Although large corrections are possible, there would have to be a conspiracy between the density and ionization structure for us to underestimate the ionization correction by a substantial amount.Comment: 36 pages, 4 figures To appear Astrophysical Journal, 20 August 2007, vol 665, no

On Love-type waves in a finitely deformed magnetoelastic layered half-space

In this paper, the propagation of Love-type waves in a homogeneously and finitely deformed layered half-space of an incompressible non-conducting magnetoelastic material in the presence of an initial uniform magnetic field is analyzed. The equations and boundary conditions governing linearized incremental motions superimposed on an underlying deformation and magnetic field for a magnetoelastic material are summarized and then specialized to a form appropriate for the study of Love-type waves in a layered half-space. The wave propagation problem is then analyzed for different directions of the initial magnetic field for two different magnetoelastic energy functions, which are generalizations of the standard neo-Hookean and Mooney–Rivlin elasticity models. The resulting wave speed characteristics in general depend significantly on the initial magnetic field as well as on the initial finite deformation, and the results are illustrated graphically for different combinations of these parameters. In the absence of a layer, shear horizontal surface waves do not exist in a purely elastic material, but the presence of a magnetic field normal to the sagittal plane makes such waves possible, these being analogous to Bleustein–Gulyaev waves in piezoelectric materials. Such waves are discussed briefly at the end of the paper

Very High Angular Resolution Science with the Square Kilometre Array

Preliminary specifications for the Square Kilometre Array (SKA) call for 25% of the total collecting area of the dish array to be located at distances greater than 180 km from the core, with a maximum baseline of at least 3000 km. The array will provide angular resolution ~ 40 - 2 mas at 0.5 - 10 GHz with image sensitivity reaching < 50 nJy/beam in an 8 hour integration with 500 MHz bandwidth. Given these specifications, the high angular resolution component of the SKA will be capable of detecting brightness temperatures < 200 K with milliarcsecond-scale angular resolution. The aim of this article is to bring together in one place a discussion of the broad range of new and important high angular resolution science that will be enabled by the SKA, and in doing so, address the merits of long baselines as part of the SKA. We highlight the fact that high angular resolution requiring baselines greater than 1000 km provides a rich science case with projects from many areas of astrophysics, including important contributions to key SKA science.Comment: 13 pages, 6 figure