Toxic effect in the lungs of rats after inhalation exposure to benzalkonium chloride

Background: Benzalkonium chloride (BAC) is a quaternary ammonium compound (QAC) toxic to microorganisms. Inhalation is one of the major possible routes of human exposure to BAC. Materials and Methods: Experiments were performed on female Wistar rats. The rats were exposed to aerosol of BAC water solution at the target concentration of 0 (control group) and 35 mg/m3 for 5 days (6 h/day) and, after a 2-week interval, the animals were challenged (day 21) with BAC aerosol at the target concentration of 0 (control group) and 35 mg/m3 for 6 h. Results: Compared to the controls, the animals exposed to BAC aerosol were characterized by lower food intake and their body weight was significantly smaller. As regards BAC-exposed group, a significant increase was noted in relative lung mass, total protein concentration, and MIP-2 in BALF both directly after the termination of the exposure and 18 h afterwards. Significantly higher IL-6 and IgE concentrations in BALF and a decrease in the CC16 concentration in BALF were found in the exposed group immediately after the exposure. The leukocyte count in BALF was significantly higher in the animals exposed to BAC aerosol compared to the controls. In the lungs of rats exposed to BAC the following effects were observed: minimal perivascular, interstitial edema, focal aggregates of alveolar macrophages, interstitial mononuclear cell infiltrations, thickened alveolar septa and marginal lipoproteinosis. Conclusion: Inhalation of BAC induced a strong inflammatory response and a damage to the blood-air barrier. Reduced concentrations of CC16, which is an immunosuppressive and anti-inflammatory protein, in combination with increased IgE concentrations in BALF may be indicative of the immuno-inflammatory response in the animals exposed to BAC aerosol by inhalation. Histopathological examinations of tissue samples from the BAC-exposed rats revealed a number of pathological changes found only in the lungs

Electrical discharge machining of difficult to cut materials

The development of industry is determined by the use of modern materials in the production of parts and equipment. In recent years, there has been a significant increase in the use of nickel-based superalloys in the aerospace, energy and space industries. Due to their properties, these alloys belong to the group of materials hard-to-machine with conventional methods. One of the non-conventional manufacturing technologies that allow the machining of geometrically complex parts from nickel-based superalloys is electrical discharge machining. The article presents the results of experimental investigations of the impact of EDM parameters on the surfaces roughness and the material removal rate. Based on the results of empirical research, mathematical models of the EDM process were developed, which allow for the selection of the most favourable processing parameters for the expected values of the surface roughness Sa and the material removal rate

Investigation of the Influence of Process Parameters on Shape Deviation after Wire Electrical Discharge Machining

New materials require the use of advanced technology in manufacturing parts of complex shape. One of the modern non-conventional technology of manufacturing difficult to cut materials is the wire electrical discharge machining (WEDM). The article presents the results of theoretical and experimental research in the influence of the WEDM conditions and parameters on the shape deviation during a rough cut. A numerical model of the dielectric flow in the gap (ANSYS) was developed. The influence of the dielectric velocity field in the gap on the debris evacuation and stability of WEDM process was discussed. Furthermore, response surface methodology (RSM) was used to build empirical models for influence of the wire speed Vd, wire tension force Fn, the volume flow rate of the dielectric Qv on the flatness deviation after the WEDM

Ocena wpływu charakteru impulsów elektrycznych w procesie EDM i WEDM na stan struktury geometrycznej powierzchni

The article discusses the results of experimental studies on the influence of the character of the pulse current and voltage on surface texture after the Wire Electrical Discharge Machining (WEDM) and the electrical Discharge Machining (EDM). The measurement circuit has been developed to determine the real current-voltage characteristics. Based on the survey developed mathematical models describing the effects of selected parameters of pulse electrical on the surface texture.W artykule przedstawiono analizę wyników badań doświadczalnych wpływu charakteru impulsów natężenia i napięcia prądu elektrycznego na strukturę geometryczną powierzchni (SGP) po obróbce wycinaniem (WEDM) i drążeniem elektroerozyjnym (EDM). Opracowano i zbudowano stanowiska pomiarowe do wyznaczenia rzeczywistych charakterystyk natężenia i napięcia prądu. Na podstawie wyników przeprowadzonych badań opracowano modele matematyczne opisujące wpływ wybranych parametrów impulsów elektrycznych na strukturę geometryczną powierzchni

Metallographic structure of the surface after EDM

W referacie przedstawiono wyniki badań wpływu parametrów wejściowych obróbki elektroerozyjnej EDM: amplitudy prądu I, czasu impulsu ton, czasu przerwy toff, przy ustalonych pozostałych parametrach obróbki na strukturę metalograficzną i fizyczną warstwy wierzchniej. Badania wykonano według trójpoziomowego planowanego eksperymentu Boxa Behnkena.The paper presents the influence of the amplitude of I, pulse time ton, the time break toff, with the remaining processing parameters on the metallographic surface structure after EDM. Research was carried out by an planned experiment three-level Box Behnken. Research has shown that the surface layer in the metallographic structure are depends on the used processing parameters. The main factor influencing the thickness of the melted layer is the duration of the pulse. Microstructural defects (cracks) seem to be strongly linked with the resulting thickness of the melted layer

Geometrical structure of the surface after EDM using graphite and copper electrode - comparison

W referacie przedstawiono wyniki badań wpływu parametrów wejściowych obróbki elektroerozyjnej: amplitudy prądu I, czasu impulsu ton, czasu przerwy toff, oraz rodzaju materiału elektrody roboczej; miedź, grafit, przy ustalonych pozostałych parametrach obróbki na wybrane parametry struktury geometrycznej obrobionej powierzchni. Badania wykonano według trójpoziomowego planowanego eksperymentu Boxa Behnkena.The paper presents the influence of the amplitude of I, pulse time ton, the time break toff, and the type of working electrode material: copper, graphite, on the surface layer parameters after EDM. Research was carried out by an planned experiment three-level Box Behnken. The developed data acquisition circuit allowed the determination of the characteristics of AC machines necessary for the proper selection of parameters implemented in the planned experiment (stable in the whole area of variation). Developed regression equations depend on the real measured parameters are characterized by a high degree of correlation. They show that the main factors affecting the geometrical structure of the surface after EMD is the current intensity and pulse duration (at fixed other parameters of treatment). Used in the processes of EDM electrode material (copper, graphite) does not significantly change the parameters of the SGP

Właściwości akustyczne i cieplne izolacji refleksyjnej

The paper presents the test results of acoustic insulation properties of reflective insulation. The experiments were performed for three different types of insulation and two values of air gap, namely 2 cm and 4 cm. A significant reduction of the sound level was recorded. Selected thermal and mechanical properties are also given in the paper