Binuclear Rhodium(II) Complexes With Selective Antibacterial Activity

Binuclear rhodium(II) complexes [Rh2Cl2(μ-OOCR)2(N-N)2] {R = H, Me; N-N = 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen)} and [Rh2(μ-OOCR)2(N-N)2(H2O)2](RCOO)2 (R = Me, Et;) have been synthesized and their structure and properties have been studied by electronic, IR and 1H NMR spectroscopy. Antibacterial activity of these complexes against Escherichia coli and Staphylococcus aureus has been investigated. The most active antibacterial agents against E. coli were [Rh2Cl2(μ-OOCR)2(N-N)2] and [Rh2(μ-OOCR)2(N-N)2(H2O)2](RCOO)2 {R = H and Me} which were considerably more active than the appropriate nitrogen ligands. The complexes show low activity against S. aureus. The activity of the complexes [Rh2(OOCR)2(N-N)2(H2O)2](OOCR)2 against E. coli decreases in the series: R=H≅CH3>C2H5>C3H7≅C4H9. The reverse order was found in the case of S. aureus

Vpliv dvostopenjskega staranja in obdelave RRA na abrazivno obrabo med tremi telesi pri zlitini AW7075

The paper presents an analysis of the influence of the heat treatment state on the abrasive wear of the AW7075 aluminium alloy. To determine the hardening state, the material hardness was measured. It was found that hardness is not the only factor that influences this type of wear. For this reason, the influence of the emerging microstructure is also analysed in the considerations. After tribological tests, microscopic observations of surface features were carried out to determine the dominant mechanisms of surface damage. The results were extended by the hardness distribution carried out on the cross-section. There were no changes in hardness that could be related to either strain hardening or structural changes caused by friction

Changes in the Assortment and Species Structure of Timber Harvested from the Polish Managed Part of Białowieża Forest

The subject of the research, which is the Polish managed part of Białowieża Forest together with Białowieża National Park, a remnant of primeval forests, is one of the most valuable forest areas in Europe. This article presents the history of the use of these forests. The assortment and species structure of the harvested timber was analyzed in detail for the Białowieża, Browsk, and Hajnówka Forest Districts from 2008 to 2017. The research is based on data from the State Forests Information System (SILP) and Forest Management Plans (PUL), as well as Nature Conservation Programs (POP). The volume of harvested timber was diversified. In 2011–2013, it was limited by a decision of the Minister of the Environment from 110,000 m3 in 2010 to 48,500 m3. This contributed to the increase of the European spruce bark beetle gradation, causing the death of spruce stands. By an annex to the Forest Management Plan issued in 2016, the Minister of the Environment increased the amount of the timber harvest. In 2017, it amounted to almost 190,000 m3, where 91% of the harvested volume was spruce, but the wood was markedly inferior in technical quality compared to previous years. Such a large increase in harvesting aroused the opposition mainly of environmental organizations and the European Commission. In April 2018, the EU Court of Justice decided that Poland violated EU law by increasing the number of felled trees in Białowieża Forest. After this decision, the Minister of the Environment repealed the earlier decision, the basis for conducting the increased wood harvesting in Białowieża Forest. Changes in the timber harvested in terms of volume, quality, and assortment, are due to the specificity of managing environmentally valuable areas. This relates to the many limitations on commercial forestry, which must take into account the need to protect nature and the legal acts regulating timber harvesting