Sintered molybdenum is widely used in the industry as an electrode for smelting furnace of glass and refractory, the crucible of rare earth metallurgy, and the thimbles for producing seamless steel tube and so on because of its strength at elevated temperature, good thermal properties, low sputtering yields and resistance to swelling. These unique properties of molybdenum make it a good candidate as a refractory metal. However, its further applications were limited by the brittleness characteristic and therefore many new molybdenum alloys were developed for improving ductility, among which the oxide dispersion strengthened molybdenum alloy (ODS Mo) is especially of interest. The ODS Mo, prepared by adding a proper amount of rare earth oxides (La 2 O 3 , Y 2 O 3 etc.) and by deforming to a large amount, exhibits a much higher recrystallization temperature than commercial pure molybdenum, [1±6] which makes ODS Mo show not only superior non-sag property and creep resistance at high temperatures but also superior strength and ductility at low temperatures as compared with the pure molybdenum. [7±9] Many explanations have been suggested on the strengthen mechanism of oxide dispersion strengthened molybdenum alloy. Hiraoka et al. attributed the improvement of low-temperature brittleness to the elongated coarse grain structure, [7] Deng shiqiang et al. thought that rare earth could decrease the density of C, N, O on the grain boundaries, [8] whereas
The general toxicity of fine particulate matter (PM2.5) has been intensively studied, but its pulmonary toxicities are still not fully understood. To investigate the changes of lung tissue after PM2.5 exposure and identify the potential mechanisms of pulmonary toxicity, PM2.5 samples were firstly collected and analyzed. Next, different doses of PM2.5 samples (5 mg/kg, 10 mg/kg, 20 mg/kg) were intratracheally instilled into rats to simulate lung inhalation of polluted air. After instillation for eight weeks, morphological alterations of the lung were examined, and the levels of oxidative stress were detected. The data indicated that the major contributors to PM2.5 mass were organic carbon, elemental carbon, sulfate, nitrate, and ammonium. Different concentrations of PM2.5 could trigger oxidative stress through increasing reactive oxygen species (ROS) and 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels, and decreasing expression of antioxidant-related proteins (nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 1 (SOD1) and catalase). Histochemical staining and transmission electron microscopy displayed pulmonary inflammation, collagen deposition, mitochondrial swelling, and a decreasing number of multilamellar bodies in alveolar type II cells after PM2.5 exposure, which was related to PM2.5-induced oxidative stress. These results provide a basis for a better understanding of pulmonary impairment in response to PM2.5.
Magnesium slag is an industrial waste residue produced in magnesium smelting. Its chemical composition is similar to Portland cement and has potential activity. After the magnesium slag is foamed, it can be made into a new type of lightweight material, and its forming, mechanical and physical properties were closely related to dry material formula, water-cement ratio and foaming agent amount. In this paper, experiments were carried out to find the ingredients and processes suitable for the forming of foamed magnesium slag, making it have certain mechanical and physical properties at the same time.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.