| 1. |
- Matveenko, L. I., et al.
(författare)
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The structure of the quasar 3C-345
- 1992
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Ingår i: Soviet Astronomy Letters. - Moscow : Rossijskaja akademija nauk / Russian Academy of Sciences. - 0320-0108. ; 18:6, s. 379-391
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Tidskriftsartikel (refereegranskat)abstract
- We study the fine structure of the quasar 3C 345 at a wavelength of 49 cm. The apparent size of the core and low-frequency variability are due to the opacity of the surrounding ionized medium and the electron density distribution. We find the distance dependence of the size and brightness temperature of the components. Relativistic plasma is being ejected into a cone, with vertex angle approximately 40-degrees in position -110-degrees. The jet consists of narrow twisted filaments.
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| 2. |
- Rantakyrö, F. T., et al.
(författare)
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High dynamic-range VLBI observations of 3C 345 at 18 cm wavelength
- 1992
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 259:1, s. 8-16
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents very high dynamic range VLBI observations of the quasar 3C345 at 18 cm wavelength at two epochs, 1981.11 and 1985.27. We find that the direction of the jet changes drastically and the surface brightness decreases with increasing distance from the core. We show that a true three-dimensional curvature of the jet in space is needed to obtain the observed decrease of intensity with distance from the core, both in an adiabatic expansion model as well as in a model where the comoving flux is constant. Our observations confirm the detection of a previously reported low surface brightness component, C0. In addition, there is a large component extended perpendicular to the jet axis which we associate with a stationary shock at a distance consistent with the expected position of the narrow line region. Models for the intensity of the jet fitted to the observed dependence of intensity with distance from the core suggests this shocked region to be the place where the jet is expanding adiabatically after having had a constant width closer to the core. A limit on the allowed viewing angle theta less-than-or-similar-to 40-degrees is derived from the lack of any detectable counterjet.
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| 3. |
- Tóth, I., et al.
(författare)
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Extraction of gallium(III) and aluminium(III) with O,O-dialkyldithiophosphoric acids
- 1990
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Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 37:12, s. 1175-1178
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Tidskriftsartikel (refereegranskat)abstract
- The extraction of Ga3+ and Al3+ with the liquid cation-exchangers di-n-butyldithiophosphoric acid (DBTPA) and di-(2-ethylhexyl)dithiophosphoric acid (DETPA) in kerosene, in the presence and absence of alcohols and tri-n-butyl phosphate (TBP) has been studied. Both Ga3+ and Al3+ can be extracted in the form of a neutral complex, MA3, but the distribution coefficient of Ga3+ is the higher by about two orders of magnitude, which can be the basis of the solvent extraction separation of gallium and aluminium. The differences can be explained by the interaction between the sulphur donor atoms of the extractants and the d10 electronic shell of Ga3+ as well as by the lower steric hindrance of ligands co-ordinated to Ga3+.
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| 4. |
- Tóth, Miklos, et al.
(författare)
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Attraction of male turnip moths Agrotis segetum (Lepidoptera : Noctuidae) to sex pheromone components and their mixtures at 11 sites in Europe, Asia, and Africa
- 1992
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Ingår i: Journal of Chemical Ecology. - 0098-0331. ; 18:8, s. 1337-1347
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Tidskriftsartikel (refereegranskat)abstract
- Selected combinations of (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetates, the pheromone components of the turnip moth AgrotisSegetum were tested for field attractancy at six, two, and three sites in Europe, Asia, and Africa, respectively. At all of the sites in Eurasia and in northern Africa the ternary mixture of the acetates captured most males, while at the sites south of the Sahara in Africa, (Z)-5-decenyl acetate alone was responsible for attraction. Differences in male attraction among the populations studied confirm the existence of significant population variation in the pheromone of A. segetum. Interpretation of the present results together with earlier studies suggests that this variation is more or less continuous in Eurasia and north Africa, while a clearly distinct pheromone type is present in the areas south of the Sahara desert.
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| 5. |
- Tóth, Miklos, et al.
(författare)
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Pheromonal Production of and Response to Optically Active Epoxydienes in Some Ceometrid Moths (Lepidoptera: Geometridae)
- 1994
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Ingår i: Zeitschrift fur Naturforschung - Section C Journal of Biosciences. - : Walter de Gruyter GmbH. - 0939-5075. ; 49:7-8, s. 516-521
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Tidskriftsartikel (refereegranskat)abstract
- In, pheromone extracts of calling female Chiasma clathrata, L. (Lepidoptera: Geometridae), a defoliator pest of alfalfa, (Z,Z,Z)-3,6,9–heptadecatriene and (Z,Z)-6,9–cis-3,4–epoxyhepta-decadiene was identified. Chiral gas chromatography using a modified cyclodextrin and synthetic reference samples proved the natural epoxide to show (3 R.4 S)-configuration. In field trapping tests, only the pure (3/R,4S)-enantiomer of the epoxide attracted males. The addition of the triene component was synergistic. Males of the sympatric species Tephrina arenaceciria Hbn. (Lepidoptera: Geometridae) were caught only in traps with baits containing the (3S,4R)-enantiomer [together with a previously described minor component, (Z,Z)-3,9–cis-6,7–epoxyheptadecadiene], In trapping tests conducted iNADifferent biotope Abraxas grossu-lariata, L. (Lepidoptera: Geometridae) males were attracted by the (3S,4R)-enantiomer, whereas the (3/L4S)-enantiomer attracted a close relative. Abraxas sylvata Scop. (Lepidoptera: Geometridae). The present results suggest that one of the key mechanisms responsible for pheromone specificity among both the two alfalfa geometrids and the two Abraxas species in their respective biotops, may be the use of different enantiomers of the same polyene-derived epoxide as a sex pheromone component. It is probable that this discrimination mechanism is widespread among moth species utilizing epoxide pheromone components.
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