101 research outputs found

    Effective ionization coefficients for low current dc discharges in alcohol vapours at low pressure

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    This paper presents results for effective ionisation coefficients (αeff/N\alpha _{\mathrm {eff}}/N, N—gas density) obtained from the breakdown voltage and emission profile measurements in low-pressure dc discharges in vapours of alcohols: methanol, ethanol, isopropanol, and n-butanol. Our results for αeff/N\alpha _{\mathrm {eff}}/N are determined from the axial emission profiles in low-current Townsend discharge and lay in the interval of reduced electric field E/N (E—electric field, N—gas density), from 1 kTd to 8.8 kTd. We also give a comparison of our experimental results with those from the available literature. Our data cover the high E/N range of the standard operating conditions and in the region where other data are available we have a good agreement

    First record and morphological characteristics of the Balkan golden loach Sabanejewia balcanica (Cobitidae) in Montenegro

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    Background and Purpose: In June 2005 the Balkan golden loach Sabanejewia balcanica (Karaman, 1922) was found for the first time in Montenegro in the Lim river. Materials and Methods: Nine specimens were measured morphometrically and meristically. Seventeen morphometric characters were measured to the nearest 0.1mmwith callipers and four meristic characters were counted. Results: The habitats in which these specimens have been found belong to the barbell zone with clear water and gravel bottom (large stones, gravel and sand), and rarely below the roots of woody plants. In this locality, beside Balkan golden loach, 9 more species were found. Conclusions: This study is a contribution to dispersion and more detailed knowledge of morphological characteristics of Balkan golden loach

    Oscillation modes of dc microdischarges with parallel-plate geometry

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    Two different oscillation modes in microdischarge with parallel-plate geometry has been observed: relaxation oscillations with frequency range between 1.23 and 2.1 kHz and free-running oscillations with 7 kHz frequency. The oscillation modes are induced by increasing power supply voltage or discharge current. For a given power supply voltage, there is a spontaneous transition from one to other oscillation mode and vice versa. Before the transition from relaxation to free-running oscillations, the spontaneous increase of oscillation frequency of relaxation oscillations form 1.3 kHz to 2.1 kHz is measured. Fourier Transform Spectra of relaxation oscillations reveal chaotic behaviour of microdischarge. Volt-Ampere characteristics associated with relaxation oscillations describes periodical transition between low current, diffuse discharge and normal glow. However, free-running oscillations appear in subnormal glow only.Comment: Submitted to: New Journal of Physic

    History of the Belanovica (Serbia) Neogene lake basin inferred from petrological and geochemical data

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    The petrological and geochemical composition of Neogene lacustrine successions and basement rocks of the Belanovica basin in Central Serbia, were investigated in three exploration boreholes, drilled in the central part of the former lake. Two boreholes accessed the basement, while the third one terminated in the lowermost Neogene interval, composed of coarse-grained clastics. Formation and diversification of the lake basin was influenced by strong syndepositional volcanic activity. The vertical distribution of selected elements from basal clastics (Cr, Ni, and Mg) and from overlying lake sediments (Ba, Sr, Na, K, etc.) indicates both the southern and northern margins of the basin, as potential source areas. The elemental concentrations are consistent with petrography. Based on the derived data, a reconstruction of the basin history is presented. The lack of index fossils resulted in a less accurate stratigraphy and the need for further updating by employment of the fission-track low-temperature thermochronometers. Additionally, outcrop studies and correlation with lake sediments in the Valjevo-Mionica basin is suggested

    Biofilm formation of achromobacter xylosoxidans on contact lens

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    Achromobacter spp. may contaminate lenses, lens cases, and contact lens solutions and cause ocular infections. The aim of this study was to investigate the possibility of isolated strain of Achromobacter xylosoxidans to form biofilm on the surface of soft contact lenses (CL), to quantify the production of the formed biofilm, and compare it with the reference strains (Pseudomonas aeruginosa, Staphylococcus aureus, and Haemophilus influenzae). Bacterial strain isolated from one contact lens case was identified as A. xylosoxidans using Vitek2 Automated System. Biofilm forming capacity of isolated strain of A. xylosoxidans and reference strains of P. aeruginosa, S. aureus, and H. influenzae on soft CL were analyzed by commonly used microtitre plate method. Our results showed that isolated strain of A. xylosoxidans was capable to form biofilm on the surface of soft contact lens. A. xylosoxidans was strong biofilm producer while all examined reference strains were moderate biofilm producers. A. xylosoxidans appears to be superior biofilm producer on soft CL compared to reference strains

    Genetic variability of pheasant (Phasianus spp) in breeding station Ristovača

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    One of the possible reasons for pheasant population number decline in past several years might be loss of adaptability in populations originated from breeding stations caused by inbreeding depression. Due to fact that adaptability is a consequence of genetic structure of the populations, the aim of this paper was the analysis of genetic variability in pheasant population from breeding station Ristovaca using molecular markers. Allozyme variability of 20 putative gene loci was detected by polyacrylamide gel electrophoresis. Polymorphism was revealed in 5 loci: Est-1, Pgd, Sod, Gpi-2 and Odh. The values of genetic variability measures - heterozigosity polymorphism, fixation indices and H/P ratio indicate low level of genetic variability and possible presence of inbreeding depression within pheasant population
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