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Number of results: 11
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Abstract

Bacteria from the Simkaniaceae family are intracellular parasites belonging to the Chlamydiales order, detected in surface waters, drinking water, chlorine water, and in wastewater. Its main representative, Simkania negevensis, is pathogenic to humans and animals, especially fishes, as it principally causes respiratory tract diseases. Bacteria from this family are also capable of surviving and existing in free-living amoebas, omnipresent in the natural environment, which makes them an additional risk for human and animal health. The aim of the present study was to search for representatives of this family in freshwaters from the Odra River and two municipal lakes (Rusałka and Goplana). Out of 100 water samples analysed, the sequence of bacteria of Simkaniaceae family was found just in 1 percent, because phylogenetic analysis revealed that the obtained OdraWCh30 sequence shows 93% similarity to Simkania negevensis strain Z as well as 87% similarity to Candidatus Syngnamydia salmonis isolate Ho-2008 and Candidatus Syngnamydia salmonis isolate VS10102006 and 84-85% similarity to endosymbiont of Xenoturbella westbladi, Simkaniaceae bacterium clone SM081012-5s and Candidatus Syngnamydia venezia strain Pi3-2. This is the first case of detecting sequence of bacteria of Simkaniaceae family in the aquatic environment in Poland.
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Abstract

This article proposes to use abrasive waterjet cutting (AWJ) for deflashing, deburring and similar finishing operations in casting. The basic requirements concerning the dimensional accuracy and surface texture of cast components are not met if visible surface flaws are detected. The experiments focused on the removal of external flash from elements made of EN-GJL-150 cast iron. The method employed for finishing was abrasive waterjet cutting. The tests were carried out using an APW 2010BB waterjet cutting machine. The form profiles before and after flash removal were determined with a Taylor Hobson PGI 1200 contact profiler. A Nikon AZ100 optical microscope was applied to observe and measure the changes in the flash height and width. The casting surface after finishing was smooth, without characteristic sharp, rough edges that occur in the cutting of objects with a considerable thickness. It should be emphasized that this method does not replace precise cutting operations. Yet, it can be successfully used to finish castings for which lower surface quality is required. An undoubted advantage of waterjet cutting is no effect of high temperature as is the case with plasma, laser or conventional cutting. This process is also easy to automate; one tool is needed to perform different finishing operations in order to obtain the desired dimensions, both internal and external.
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Abstract

Ablation casting is a technological process in which the increased cooling rate causes microstructure refinement, resulting in improved mechanical properties of the final product. This technology is particularly suitable for the manufacture of castings with intricate shapes and thin walls. Currently, the ablation casting process is not used in the Polish industry. This article presents the results of strength tests carried out on moulding sands based on hydrated sodium silicate hardened in the Floster S technology, intended for ablation casting of the AlSi7Mg (AK7) aluminium alloy. When testing the bending and tensile strengths of sands, parameters such as binder and hardener content were taken into account. The sand mixtures were tested after 24h hardening at room temperature. The next stage of the study describes the course of the ablation casting process, starting with the manufacture of foundry mould from the selected moulding mixture and ending in tests carried out on the ready casting to check the surface quality, structure and mechanical properties. The results were compared with the parallel results obtained on a casting gravity poured into the sand mould and solidifying in a traditional way at ambient temperature.
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Abstract

The paper deals with a study of relations between the measured Ra, Rq, Rz surface roughness parameters, the traverse speed of cutting head v and the vibration parameters, PtP, RMS, vRa, generated during abrasive water jet cutting of the AISI 309 stainless steel. Equations for prediction of the surface roughness parameters were derived according to the vibration parameter and the traverse speed of cutting head. Accuracy of the equations is described according to the Euclidean distances. The results are suitable for an on-line control model simulating abrasive water jet cutting and machining using an accompanying physical phenomenon for the process control which eliminates intervention of the operator.
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Abstract

This study illustrates the benefits of statistical techniques to analyze spatial and temporal variations in water quality. In this scope water quality differentiation caused by anthropogenic and natural factors in the Tahtali and Balçova reservoirs in western Turkey was investigated using discriminant analysis-DA, Mann Whitney U techniques. Effectiveness of pollution prevention measures was analyzed by Mann Kendall and Sen’s Slope estimator methods. The water quality variables were divided into three groups as physical-inorganic, organic and inorganic pollution parameters for the study. Results showed that water quality between reservoirs was differentiated for “physical-inorganic” and “organic pollution” parameters. Degree of influence of water quality by urbanization was higher in the Tahtali reservoir and in general, no trend detection at pollution indicators explained by effective management practices at both sites.
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Abstract

The aim of the presented research was to analyse the pollution of the Kozłowa Góra Dam Reservoir with PCBs (28, 52, 101, 118, 138, 153, 180) and heavy metals (Zn, Cu, Ni, Cd, Pb, Cr). The investigated water and bottom sediments were sampled from two sampling points in November, 2009. The sampling points were located in the southern part of the Kozłowa Góra Dam Reservoir. The samples of bottom sediments were taken from the surface layer of 5 cm thickness. The extraction of PCBs from the bottom sediments was performed according to the EPA 3550B standard. For the sequential extraction analysis of metals from the sampled bottom sediments, the method suggested by Tessier was applied. Based on the obtained results the water and bottom sediments from the Kozłowa Góra Dam Reservoir were polluted with polychlorinated biphenyls. The highest concentration of the investigated PCB congeners in bottom sediments was determined in the sampling point No. 1 (2.78 µg/kg d.m.), whereas in the sampling point No. 2 this level was over 20-fold lower which might result from the inflow of these compounds with the waters of the Brynica river. In both sampling points the investigated bottom sediments were predominated by higher chlorinated PCBs with comparable contents of 86% and 85%, respectively. The level of pollution in the investigated bottom sediments (calculated per dry matter) with polychlorinated biphenyls did not exceed the level of TEL (< 0.02 mg/kg). The PEL value (3.5 mg/kg) was exceeded in the case of cadmium in the bottom sediment from the sampling point No. 2 and also lead (91 mg/kg) from both sampling points. The first two fractions with the mobile forms of metals are the most sensitive fractions to any changes of the environmental conditions in the benthic zone. In those fractions significant contents of lead, cadmium, nickel and zinc were observed.
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