Background: Hospital equipment made from copper alloys can play an important role in complementing traditional methods of disinfection. Aims of the study: The aim of this study was to assess the dynamics of the antimicrobial properties of selected copper alloys in different simulations of environmental conditions (with organic contamination vs. without organic contamination), and to test alternatives to the currently used testing methods. Materials and Methods: A modification of Japanese standard JIS Z 2801 as well as Staphylococcus aureus (SA) and Escherichia coli (EC) suspended in NaCl vs. tryptic soy broth (TSB) were used in tests performed on seven commonly used copper alloys, copper, and stainless steel. Results: A much faster reduction of the bacterial suspension was observed for the inoculum prepared in NaCl than in TSB. A faster reduction for EC than for SA was observed in the inoculum prepared in NaCl. The opposite results were found for the inoculum based on TSB. A significant correlation between the copper concentration in the copper alloys and the time and degree of bacterial suspension reduction was only observed in the case of EC. Conclusions: This study confirmed the antimicrobial properties of copper alloys, and additionally showed that Staphylococcus aureus was more resistant than Escherichia coli in the variant of the experiment without organic contamination. However, even for SA, a total reduction of the bacterial inoculum’s density took no longer than 2 h. Under conditions simulating organic contamination, all of the tested alloys were shown to have bactericidal or bacteriostatic properties, which was contrary to the results from stainless steel.

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Currently, there is a worldwide search for new forms of materials with properties that are significantly improved in comparison to materials currently in use. One promising research direction lies in the synthesis of metals containing modern carbon materials (e.g., graphene, nanotubes). In this article, the research results of metallurgical synthesis of a mixture of copper and two different kinds of carbon (activated carbon and multiwall carbon nanotubes) are shown. Samples of copper-carbon nanocomposite were synthesized by simultaneously exposing molten copper to an electrical current while vigorously stirring and adding carbon while under an inert gas atmosphere. The article contains research results of density, hardness, electrical conductivity, structure (TEM), and carbon decomposition (SIMS method) for the obtained materials.

A novelty in electroenergetics of the recent years are anti-blackout conductors of the HTLS type. These conductors allow for an above average increase of the transmission capacity of electric energy through overhead lines. The high temperature work of such conductor is possible with the use of thermally resistant aluminium alloys with the addition of zirconium. Compared to the traditionally applied material of the EN AW 1370 class, those alloys' permissible work temperature is at the level of 150 to 230 • C (aluminium 80 • C). The production technology for the alloys of this type includes a line of continuous casting and rolling of the wire rod, and next, its long-term heat treatment. The aim of the process of the heating of the wire rod is obtaining the desired level of the material's properties, which will make it possible to obtain the final properties of the wires assigned for the creation of conductors. The paper presents the results of the studies aiming at the description of the influence of the heat treatment of the material obtained in various production process conditions on its mechanical and electric properties.Keywords: aluminium alloys, AlZr, conductive materials, heat treatment, electric conductivity Nowością ostatnich lat w elektroenergetyce są antyblackoutowe przewody typu HTLS. Przewody te umożliwiają ponadprzeciętne zwiększenie zdolności przesyłu energii elektrycznej liniami napowietrznymi. Wysokotemperaturowa praca takiego przewodu, możliwa jest poprzez wykorzystanie odpornych cieplnie stopów aluminium z dodatkiem cyrkonu. Stopy te w porów-naniu z tradycyjnie stosowanym materiałem w gatunku EN AW 1370 posiadają dopuszczalną temperaturę pracy na poziomie 150 do 230 • C (aluminium 80 • C). Technologia produkcji tego typu materiałów obejmuje linię ciągłego odlewania i walcowania walcówki, a następnie jej długoczasową obróbkę cieplną. Celem procesu wygrzewania walcówki jest osiągnięcie wymaganego poziomu własności materiału, który umożliwi uzyskanie końcowych własności drutów, przeznaczonych do budowy przewodów. W pracy przedstawiono wyniki badań zmierzających do określenia wpływu parametrów obróbki cieplnej materiału uzyskanego w rożnych warunkach procesu produkcyjnego na jego własności mechaniczne i elektryczne.

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The properties of copper in its solid state are strongly affected by the crystallization conditions of the liquid material. ETP grade copper (Electrolytic Tough Pitch Copper) contains oxygen, which causes Cu2O oxide to crystallize in the interdendritic spaces during solidification process which due to the shape of continuous casting mould and the feed of liquid copper during the crystallization process in strand casting might cause a high risk of macrosegregation of oxygen in the copper structure. In the current paper the implied interactions of the dendritic structure of the copper strand in terms of homogeneity at the cross-section of its electrical, mechanical and plastic properties determined based on the samples taken parallelly and perpendicularly to the surface of the dendritic boundaries were analysed. The obtained results were confronted with scanning electron microscopy (SEM) images of the fractures formed during uniaxial tensile test. It has been observed that when the crystallites were arranged perpendicularly to the tensile direction the yield strength (YS) was lower and the fractures were brittle. On the other hand, when the crystallites were arranged parallelly to the tensile direction the fractures were plastic and elongated necking was observed along with the higher YS and total elongation values. The differences in values vary in terms of the applied direction of the tensile force. A characteristic positioning of the Cu2O oxide particles inside the fracture depending on the crystallite alignment and the direction of the applied tensile force has been observed.

BackgroundDespite the employment of sanitary regimes, contact transmission of the aetiological agents of hospital infections is still exceedingly common. The issue of microbe transmission becomes particularly important when facing multidrug-resistant microorganisms such as methicillin-resistant staphylococci. In the case of deficiencies in cleaning and disinfection procedures, hospital equipment made of copper alloys can play an important role, complementing traditional hospital hygiene procedures.The objective of this study was to characterize staphylococcal strains isolated from touch surfaces in Polish hospital wards in terms of their drug resistance, ability to form biofilm and susceptibility to antimicrobial activity of copper alloys.MethodsThe materials for the study were 95 staphylococcal strains isolated from touch surfaces in 13 different hospital wards from Małopolska province (the south of Poland). Phenotypic and genotypic antibiotic resistance were checked for erythromycin, clindamycin, gentamycin, ciprofloxacin, trimethoprim/sulfamethoxazole and mupirocin. Biofilm formation ability for the tested strains was checked with the use of culture on Congo red agar. Susceptibility to copper, tin bronze, brass and new silver was tested using a modification of the Japanese standard.ResultsOver 67% of the analysed staphylococcal strains were methicillin-resistant (MR). Four strains were resistant to all of the tested antibiotics, and 14 were resistant to all except mupirocin. Strains classified as MR had significantly increased resistance to the remaining antibiotic groups. About one-third of the analysed strains revealed biofilm-forming ability. Among the majority of species, biofilm-forming and non-biofilm-forming strains were distributed evenly; in the case of S. haemolyticus only, negative strains accounted for 92.8%. Susceptibility to copper alloys was different between strains and rather lower than in the case of the SA strain selected for comparison.ConclusionsCoagulase-negative staphylococci, the most commonly isolated in Polish hospital wards, should not be neglected as an infection risk factor due their high antibiotic resistance. Our experiments confirmed that touch surfaces made of copper alloys may play an important role in eliminating bacteria from the hospital environment.

The subject of the present article consists in obtaining the wire production material with the controlled, during the heat treatment, level of electrical and mechanical properties. In the case of the AlZr alloys the appropriate strength properties are obtained in the technological process through the introduction of the specified value of the cold working (work-hardening). In turn,the AlZr alloy resistivity value is dependent on both the amount of the zircon additive and its placement characteristics in the aluminium structure (solid solution or emissions). The paper presents comparative resistivity and hardness tests of the AlZr alloy material with the zircon content ranging from 0.05 to 0.32% mas. Zr produced in the continuous casting technology as well as in the continuous casting and rolling technology.