New methods and equipment of decametric radio astronomy for continuum observation at the UTR-2 radio telescope

At present time the modernization of the giant decametric radio telescope UTR-2 is under way. New back-end facilities and methods which open up new possibilities for radio astronomical observations are developed. Some equipment was made in cooperation with Austrian and French radio astronomers. Current back-end facilities and methods used at the UTR-2 radio telescope are described and compared with former traditional methods, equipment and their characteristics. Some prospects regarding current progress in developing new generation of back-end facilities are also discussed. The main focus of the presentation is the observation methods and equipment applied at the UTR-2 radio telescope for the investigation of continuum radio sources: Galactic background, discrete sources (preparation for the catalogue of sources in the whole Northern Sky), SNR, HII regions. Some results of using the new back-end facilities (such as Digital Spectral Polarimeter) and processing methods are presented

GENE TRANSFER IN TOBACCO MITOCHONDRIA IN VITRO AND IN VIVO

Earlier, we had showed that isolated mitochondria from different organisms can import DNA. Exploiting this mechanism, we assessed the possibility of genes transfer in tobacco mitochondria in vitro and in vivo. Whereas homologous recombination is a rare occasion in higher plant nuclei, recombination between the large direct repeats in plant mitochondrial genome generates its multipartite structure. Following transfection of isolated organelles with constructs composed of a partial gfp gene flanked by mitochondrial DNA fragments, we showed the homologous recombination of imported DNA with the resident DNA and the integration of the reporter gene. The recombination yielded an insertion of a continuous exogenous DNA fragment including the gfp sequence and at least the 0.5 kb of the flanking sequence on each side. Using of transfection constructs carrying multiple sequences homologous to mitochondrial DNA could be suitable for insertion of a target gene into any region of the mitochondrial genome, which turns this approach to be of a general and methodical importance. Usually mitochondrial reactive oxygen species (ROS) level is under strict control of the antioxidant system including the Mn-containing superoxide dismutase (MnSOD). MnSOD is presented in multiple forms encoded by several genes in plants. Possibly, this enzyme, beside its catalytic function, fulfills as well some unknown biochemical functions. Thus, one of maize SOD enzymes (SOD3.4) could bind with mitochondrial DNA. Another SOD form (SOD3.1) is located in close proximity to mitochondrial respiratory complexes, where ROS are generated. To study possible physiological functions of this enzyme, we cloned the maize SOD3.1 gene. Compared to the SOD3.4, this enzyme didn't demonstrate DNA-binding activity. At the same time, SOD3.1 didn't show non-specific DNA-hydrolyzing activity as Cu/ZnSOD does. It means that this enzyme might have some DNA protective function. We made NtPcob-sod3.1-IGR-cob* genetic construct with integrative properties. It contains the selective gene and the gene of interest under control of the 5'-regulatory regions of Arabidopsis orf262 gene and the tobacco cob gene. We used modified variant of the tobacco apocytochrome b gene as a gene for selection with the nucleotide substitution G128T (G43V) which results in antimycin A resistance. The maize sod3.1 gene was used as a gene of interest. The construct was delivered into tobacco callus cells and leaf disks by biolistic method. The callus lines demonstrating the high growth rates in the presence of antimycin A in comparison with the non-transformed control lines were selected. PCR analysis of transformed callus lines revealed the presence of heterologous maize sod3.1 sequence and the integration of the construct elements in tobacco mitochondrial genome

Physicochemical and Technological Aspects of the Hydrothermal Modification of Complex Sorbents and Catalysts. Part I. Modification of Porous and Crystalline Structures

This paper deals with the hydrothermal modification of the physicochemical properties of complex mineral sorbents and catalysts. The hydrothermal modification of alumina, magnesia, ferric oxide and zirconia/silica hydro- and xero-gels as well as other complex adsorbents obtained by the coprecipitation and mechanical stirring of suitable components is discussed. The paper deals with the following topics: (a) the physicochemical bases of the hydrothermal method; (b) methodological and technological problems of the hydrothermal treatment of adsorbents; (c) hydrothermal modification of porous structure parameters (specific surface area, pore volume and size); and (d) characteristics of the hydrothermal modification of the porous structure of multicomponent adsorbents and catalysts. In addition, the mechanism of the hydrothermal modification of the porous structure of composite materials is discussed

Physicochemical and Technological Aspects of the Hydrothermal Modification of Complex Sorbents and Catalysts. Part II. Modification of Phase Composition and Mechanical Properties

Two main ways of applying the method of solid hydrothermal treatment have been considered: (a) hydrothermal modification of polycrystalline adsorbents and catalysts; and (b) hydrothermal synthesis of materials possessing regular porosity (zeolite-like, laminar and others). Modification processes of phase composition and mechanical properties of complex adsorbents and catalysts were discussed. The essential features of hydrothermal crystallization in multicomponent systems have been presented

Studies of the Effects of Aerosilogel Modification by Organic Acids under High Pressures

Preliminary studies of silica surface modification by means of some organic acids under high reagent pressures were carried out. The reaction took place in a steel autoclave. Suitably granulated aerosilogel and acetic, mono- and trichloro-acetic as well as sulphosalicylic acids were used. Physical and chemical adsorption processes were checked by infrared spectroscopy, thermogravimetry and Potentiometric titration. The specific surface area and total volume of pores of the prepared samples were determined. The studies showed some possibilities of attaching organic radicals containing an acid group to the silica surface. This process can be accomplished in one stage

Some Peculiarities of Silica Modification Under High Reagent Pressure. I. Methodological Aspects

The effect of the following factors on the chemical and geometrical modification of aerosilogel (prepared from aerosil) was studied: the physicochemical characteristics of the modifying reagent pressures, the preparation conditions for the silica surface, the reaction temperature, the reagent pressures, the duration of treatment and the method employed for the modification process. The course of the surface reaction was followed by IR spectroscopy, differential thermal analysis and adsorption. During high-pressure modification, the geometrical parameters of the porous silica structure may be changed

Some Peculiarities of Silica Modification under High Reagent Pressure. II. Influence of Chemical Nature of Modifying Reagent

The modes of interaction between organic substances and aerosilogel at high pressures and high temperatures were considered. The analysis was performed on the basis of data from IR spectroscopy and differential thermal analysis, and the porous structure characteristics of the modified aerosilogel. The following types of substances were used as modifiers of the silica surface: (a) substances which did not interact chemically with the silica surface; (b) substances capable of polymerization or polycondensation; and (c) substances capable of chemical reaction with the surface. From an analysis of data obtained for 26 adsorbents, it results that depending on the nature of the substance used for modification such substances can promote the process of silica mass transfer. During this process, the possibility occurs of the occlusion of the substances inside silica globules, changes in the parameters of the porous structure, physical or chemical bonding of the modifier molecules with the aerosilogel surface, destruction of the reaction products, etc. The mechanism of the reaction was discussed

Earliest recorded ground-based decameter wavelength observations of Saturn’s lightning during the giant E-storm detected by Cassini spacecraft in early 2006

International audienceWe report the history of the first recorded ground-based radio detection of Saturn’s lightning using the Ukrainian UTR-2 radiotelescope at frequencies from 20 to 25 MHz. The observations were performed between 29 January and 3 February 2006, during which lighting activity (E-storm) on Saturn was detected by the radio experiment onboard Cassini spacecraft. The minimum detectable flux density (1σ1σ-level) at UTR-2 reached 40 Jy (View the MathML source1Jy=10-26Wm-2Hz-1) for narrowband observations (View the MathML sourceΔf=10kHz) and 4 Jy for broadband observations (View the MathML sourceΔf=1MHz), for an effective telescope area of View the MathML source≈100,000m2 and integration time of 20 ms. Selection criteria including comparison of simultaneous ON/OFF-source observations were applied to distinguish detection of lightning-associated radio pulses from interference. This allowed us to identify about 70 events with signal-to-noise ratio more than 5. Measured flux densities (between 50 and 700 Jy) and burst durations (between 60 and 220 ms) are in good agreement with extrapolation of previous Cassini measurements to a ground-based observer. This first detection demonstrates the possibility of Solar System planetary lightning studies using large, present and future ground-based radio instruments. The developed methods of observations and identification criteria are also implemented on the UTR-2 radio telescope for the investigation of the next Saturn’s storms. Together with recently published UTR-2 measurements of activity measured after the 2006 storm reported here, the results have significant implications for detectable planetary radio emission in our Solar System and beyond