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Sheets of flame‐retardant cross‐linked polyethylene (FR‐XLPE) were aged thermally at 80, 100, 135, and 155 °C for various periods from 100 to 800 h. They were also aged concurrently by heat and gamma rays at the same temperatures for the same periods at a dose rate of 100 Gy/h. For these sheets, we measured indenter modulus, elongation at break, complex permittivity, and absorption spectra at midinfrared and THz frequencies. As a result, it has become clear that the aging at 135 °C makes FR‐XLPE hard regardless of the presence of concurrent irradiation of gamma rays. This makes the transport of charge carriers difficult. Therefore, both the real and the imaginary parts of complex permittivity decrease, which is significant if the measurement frequency is low. However, this tendency becomes opposite as the samples were aged at 155 °C by heat or concurrently by heat and radiation. Using indenter modulus as an indicator, it has become clear that the aging progress is composed of two different stages, which could be a good clue to the explanation of these opposite changes in complex permittivity. On the other hand, the samples aged at 155 °C concurrently by heat and radiation show larger values in the indenter modulus and in two parts of complex permittivity than the samples aged at the same temperature only by heat. This is probably due to the oxidative degradation induced by the cooperative reaction of heat and radiation. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), native to Asia, is a destructive invasive pest of ash Fraxinus spp. in U.S.A., Canada and European Russia. It is spreading quickly and will probably soon be detected in other European countries., Information about the life cycle of the pest is needed for detection and survey efforts, development of control options and predicting the potential range in Europe. The life cycle has been studied in North America and Asia, although it has not previously been studied in European Russia., The number of larval instars and the duration of development of A. planipennis in European Russia were determined. Distributions of width of epistome and length of urogomphi indicated four larval instars. The number of excretory ducts and the presence of ledges did not provide a clear differentiation between instars. Development in most of the specimens took 2 years., Generation time is flexible. In warmer regions (Tianjin), most individuals finish development in 1 year, whereas, in colder regions (Moscow, Changchun, Harbin), it takes 2 years. In intermediate climatic regions (Michigan), the ratio of 1 : 2-year life cycles depends on additional factors. The flexibility of the life cycle allows A. planipennis to establish in regions with different climates. [ABSTRACT FROM AUTHOR]