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Povzetek: Background. Microcystins (MCs) are cyclic heptapeptides that are considered tobe liver specific toxins. They are potent tumour promoters and recent studies indicate that they are also genotoxic. In this study we measured DNA damage in lymphocytes, liver, kidney (cortex and medulla), lung, spleen and brain cells of male Fisher F344 rats that were exposed to sublethal dose (every second day 10 Ugžkg b.w.č i.p) of microeysrin-YR (MCYR) for one month. Methods. At the end of exposure the animals were sacrificed, the lymphocytes were isolated from blood taken from jugular vein, liver cells were obtained byperfusion with collagenase A and the cells from other organs were isolated by incubating small tissue pieces with eollagenase A. The DNA damage in isolated cells was measured with the single cells gel electrophoresis (SCGE) also called the comet assay. Results. A significant increase of the % tail DNAin MCYR-exposed animals compared to the nonexposed control ones was observed in brain (2.5 fold), liver (2.1 fold), kidney medulla (1.9 fold), kidney cortex (1.8 fold) and lung (1.7 fold) cells, while the DNA from lymphocytes and spleen cells was not affected. Conclusion. This study demonstrated that subehronic exposure to sublethal doses of MCs can induce systemicgenotoxicity in mammals, and it affects not only the liver but also other vital organs.
Ključne besede: DNA damage, comet assay, cyanobacteria, bacterial toxins, rats, inbred F344
Objavljeno v DiRROS: 20.02.2024; Ogledov: 138; Prenosov: 37
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Povzetek: Bridges can be subjected to damaging environmental actions due to flooding and seismic hazards. Flood actions that result in scour are a leading cause of bridge failure, while seismic actions that induce lateral forces may lead to high ductility demand that exceeds pier capacity. When combined, seismic actions and scour can lead to effects that depend on the governing scour condition affecting a bridge. Loss of stiffness under scour can reduce the ductility capacity of a bridge but can also lead to an increase in flexibility that may reduce seismic inertial forces. Conversely, increased flexibility can lead to deck collapse due to support loss, so there exists some uncertainty about the combined effect of both phenomena. A necessary step towards the performance assessment of bridges under flooding and seismic actions is to calibrate numerical models that can reproduce structural responses under different actions. A further step is verifying the achievement of performance goals defined by codes. Structural health monitoring (SHM) techniques allow the computation of performance parameters that are useful for calibrating numerical models and performing direct checks of performance goal compliance. In this paper, various strategies employed to monitor bridge health against scour and seismic actions are discussed, with a particular focus on vibration-based damage identification methods.
Ključne besede: scour, seismic, damage, hazard, vibration-based methods
Objavljeno v DiRROS: 29.11.2023; Ogledov: 192; Prenosov: 108
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Povzetek: This paper develops a novel method of bridge damage detection using statistical analysis of data from an acceleration-based bridge weigh-in-motion (BWIM) system. Bridge dynamic analysis using a vehicle-bridge interaction model is carried out to obtain bridge accelerations, and the BWIM concept is applied to infer the vehicle axle weights. A large volume of traffic data tends to remain consistent (e.g., most frequent gross vehicle weight (GVW) of 3-axle trucks); therefore, the statistical properties of inferred vehicle weights are used to develop a bridge damage detection technique. Global change of bridge stiffness due to a change in the elastic modulus of concrete is used as a proxy of bridge damage. This approach has the advantage of overcoming the variability in acceleration signals due to the wide variety of source excitations/vehicles–data from a large number of different vehicles can be easily combined in the form of inferred vehicle weight. One year of experimental data from a short-span reinforced concrete bridge in Slovenia is used to assess the effectiveness of the new approach. Although the acceleration-based BWIM system is inaccurate for finding vehicle axle-weights, it is found to be effective in detecting damage using statistical analysis. It is shown through simulation as well as by experimental analysis that a significant change in the statistical properties of the inferred BWIM data results from changes in the bridge condition.
Ključne besede: bridge health monitoring, bridge WIM, structural dynamics, damage detection, vehicle-bridge interaction
Objavljeno v DiRROS: 12.09.2023; Ogledov: 279; Prenosov: 140
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Povzetek: The research aimed to determine the start, end and duration of leafing phases, the degree of plant damage caused by late spring frost, and the retention of leaves in autumn. The research was conducted in the international common beech provenance test in Bosnia and Herzegovina. The test contains eight provenances from Bosnia and Herzegovina, four from Germany, three from Serbia, two each from Croatia, Romania and Switzerland, and one from Hungary. Leafing phenology, canopy damage caused by late spring frost, and leaf retention were assessed in 2019. Most provenances started opening buds on 17 April 2019. Complete canopy damage affected the highest percentage of plants in provenance BW Bad Wildbad, Germany (68 %), and the lowest in provenance Konjuh Kladanj, Bosnia and Herzegovina (3.2 %). Provenance Herzogenbuchsee from Switzerland had the highest percentage of winter leaf retention (37.5 % of plants). The results can be used in choosing provenances that are resistant to low temperatures in zones of late spring and early autumn frost.
Ključne besede: common beech, international provenance test, leafing phenophases, frost damage, winter leaf retention
Objavljeno v DiRROS: 01.12.2021; Ogledov: 3480; Prenosov: 1925
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Povzetek: The Zasavje district has been heavily affected by air pollution due to mining,the presence of a coal-fired power plant, and industry. The extent of forest damage differs according to location because of specific climatic and orographic characteristics. Norway spruce damage was estimated by two methods at 10 locations in the Zasavje district using the Slovenian forestry method for the estimation of forest damage (KOVA et al. 1995), and a Czech method forestimation of damage to the branching system and needle loss and discoloration (CUDLIN & CHMELIKOVA 1995). Comparison of the results obtained by the two methods gave similar damage assessments at heavily polluted sites, although the data obtained by the two methods differ due to several environmental parameters. The Czech method did not give as good results as wasexpected. A possible reason might be that spruce trees in the investigated locations are less damaged than those in the Czech Republic, where the method was developed.
Ključne besede: air pollution, Norway spruce, Picea abies (L.), tree damage, Zasavje, propadanje gozda, poškodovanost drevja, gozdno drevje, onesnaženost zraka, Zasavje, smreka, Picea abies (L.) Karst.
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4614; Prenosov: 1909
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