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.
Chronic and acute wounds pose a huge burden on patients and health care systems. Early diagnosis and prompt treatment is essential in preventing further complications such as limb amputation and infection. Recent progress in our understanding of different wounds’ pathophysiology,
has resulted in developing different drug delivery vehicles to target different phases of wound healing. During the past decade, microspheres and nanospheres have gained significant attention in drug delivering wound dressings. These vehicles have gained popularity largely due their biocompatibility,
biodegradability, their high capacity to deliver various drug types, and long term sustained release profile. In the current review, we will discuss the challenges and prospects of microsphere and nanosphere-based drug delivery systems in wound healing.
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.
This paper presents a multiband planar antenna with a third-order toroidal coupling structure that has potential applications in mobile communications. The antenna is fed using a coplanar waveguide structure. The radiating body model of the antenna is obtained by scaling and nesting twice in equal proportions based on a first-order toroid. The above patch was printed on a 42 × 55 × 0.1 mm3 polyimide flexible dielectric substrate. This article explores the effect of bending in different directions on the antenna performance and explores the effect of coupling with the human body on the antenna S11. The antenna was simulated using a high-frequency structure simulator and measured in an electromagnetic microwave darkroom. The simulation results of the antenna match well with the measured results, and the maximum gain of its band coverage is 4.39 dBi. The antenna can cover the frequency bands of TD-LTE (B-TrunC) (1.447–1.467 GHz), LTE42/43 (3.4–3.8 GHz), WiMAX (3.3–3.8 GHz), 5G band n78 (3.4–3.8 GHz), WLAN (5.15–5.35 GHz), 5G (5.725–5.825 GHz), and other commercial bands.
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