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The structural adhesive bonding of aluminum is widely used in the aircraft and automotive industries. The surface preparation of aluminum prior to adhesive bonding plays a significant role in improving the bonding strength. Surface cleanliness, surface roughness, and surface chemistry can be controlled, primarily, by proper surface treatment methods. In this study, the effect of varying the chemical treatment period on the adhesive bonding characteristics was investigated. An epoxy adhesive was used to join the treated surfaces, and the bond strengths were evaluated via single lap-shear (SLS) tests in pristine, as well as degraded, conditions. The surface morphology, chemistry, and corrosion properties of the surfaces with chemical treatments were characterized using various surface analytical tools, such as scanning electron microscopy, an energy dispersive spectrometer (SEM/EDX), and an electrochemical workstation. Excellent adhesion characteristics, with the complete cohesive failure of the adhesive, were encountered on the surfaces of the H2O2-treated samples. The H2O2-treated samples exhibited the highest initial bond strength, reaching 22.5 ± 0.5 MPa, and showed a decrease of only 10% (to 18.1 ± 0.2 MPa) after aging under extreme humidity and temperature conditions (70 °C and 100% R.H. for 4 weeks). The chemical treatment reported in this work is a very simple method to produce durable joints. [ABSTRACT FROM AUTHOR]

The effects of neutron and gamma radiation on shielding materials directly influence the safety of nuclear facilities. In this study, a B4C/epoxy resin shielding material was fabricated. The mechanical properties, fracture microstructural morphology, characteristic groups, and thermal degradation of the shielding material under two different irradiation conditions, 1 MGy gamma and superimposed 1.19×1015 cm-2 neutron radiation, were compared. After gamma irradiation for 11.6 d and superimposed neutron irradiation for 3 h, the mechanical properties of the shielding material continued to decrease; however, they did not decrease to 50% of those before irradiation, and radiation degradation occurred instead of material failure. Compared with separate gamma irradiation, the peak intensity in the 1H-NMR spectra of the shielding material near δ=7 did not change significantly after the additional neutron irradiation, indicating that there was no further degradation of the C‒H bond on the benzene ring. At 50% loss in mass, the temperature decreased from 526.3 °C before irradiation to 453.2 °C after gamma irradiation and 463.9 °C after gamma superimposed neutron irradiation, demonstrating the decrease in thermal stability.

Moso bamboo (Phyllostachys edulis (Carrière) J.Houz.) is a fast-growing species that commonly invades neighboring broadleaf forests and has been widely reported in subtropical forest ecosystems. However, little is known about the effect on soil phosphorus (P) bioavailability and its potential influence factor during the P. edulis expansion. Here, the four soil P bioavailable fractions (i.e., CaCl2-P, Citrate-P, Enzyme-P, and HCl-P), acid phosphatase activity, iron and aluminum oxides (Fed and Ald), and soil total P pool at depths of 0–10 cm, 10–20 cm, and 20–40 cm were measured in three expanding interfaces (a broadleaf forest, a mixed bamboo–broadleaf forest, and a pure P. edulis forest) in subtropical forests of southern China. Regardless of soil depths, the CaCl2-P content was significantly lower in the mixed bamboo–broadleaf forest than the other two forest types, with contents ranging from 0.09 to 0.16 mg/kg, whereas the HCl-P content was significantly lower in the broadleaf forest, with contents ranging from 3.42 to 14.33 mg/kg, and the Enzyme-P content and acid phosphatase activity were notably lower in P. edulis forest with contents of 0.17–0.52 mg/kg and 68.66–74.80 μmol MUF released g−1 min−1, respectively. Moreover, the soil total P pool was enhanced in the mixed bamboo–broadleaf forest in 0–10 cm depth compared to broadleaf and P. edulis forests, with increases of 27.40% and 31.02%, respectively. The redundancy analysis showed that soil pH plays an important role in regulating soil P bioavailability during the P. edulis expansion (p < 0.01). From the above results, the invasion of P. edulis into broadleaf forests has resulted in soil P bioavailability and storage capacity. The results of this study suggest that when P. edulis invades broadleaf forests, it could affect the soil P bioavailability by elevating soil pH, which in turn drives and facilitates the completion of the expansion. This is important for understanding P cycling during the P. edulis forest expansion in subtropical regions. [ABSTRACT FROM AUTHOR]