A B S T R A C T This article summarises the uniaxial tension tests for 20 notched bars fabricated from highstrength steel Q345 specified in Chinese National Standards. The effects of the notch radius, r, and that of the notch depth ratio, d /D, on the ductility and fracture resistance of this high strength steel are examined. The experimental data are further analyzed using a generalized yield model together with an elliptical fracture stress envelope originally proposed by the first author. The experimental results demonstrate that cracks initiate at the notched section, with the fracture surface filled with many dimples and shearing marks. Specimens with a sharper notch radius (a smaller r) and a larger notch depth (a smaller d /D ratio) show poor ductility, but high fracture strength. The stress field computed from the numerical procedure including the generalized yield model indicates that the crack initiation occurs at the centre of the notched section which experiences the highest stress triaxiality ratio (σ m /σ seq ). As the stresses at the notched section reach the limiting values determined from the elliptical fracture criterion, macroscopic fracture failure in the notched bar occurs.

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Brown planthopper (BPH), white‐backed planthopper (WBPH) and small brown planthopper (SBPH), are the closely related rice pests that perform differentially on wheat plants. Using fecundity as a fitness measure, we found that SBPH well‐adapted on wheat plants, followed by WBPH, while BPH had the worst performance. The transcriptomic responses of SBPH and BPH to wheat plants have been compared previously. To understand the different fitness mechanisms of three planthoppers, this study first investigated the transcriptomic responses of WBPH to rice and wheat plants. Genes involved in detoxification, transportation and proteasome were significantly enriched in WBPH in response to different diets. Moreover, comparative analysis demonstrated that most co‐regulated genes in BPH and SBPH showed different expression changes; whereas most co‐regulated genes in BPH and WBPH exhibited similar expression changes. Subsequently, this study also investigated the influences of host plants on the bacterial community of three planthoppers. The three planthoppers harboured distant diversity of bacterial communities. However, there was no dramatic change in bacterial diversity or relative abundance in planthoppers colonized on different hosts. This study illustrates generic and species‐specific changes of three rice planthoppers in response to different plants, which deepen our understanding towards the host fitness for planthopper species.

In this paper, the methods of preparation of Ge-Se-Sb glasses with low impurity content were developed, and a large Ge-Sb-Se glass rod (φ85×80mm) with good quality was obtained. The physical and optical properties of the glass were measured. The optical homogeneity (Δn) at 2μm at different places inside the same bulk was less ±2×10 -4 . In order to accurately evaluate the infrared resolution of our prepared glass, a lens of f 19mm F/#1.3 was used to evalue its modulation transfer function (MTF) performance. The MTF value at 20cycles/mm for 20°C was 0.52. The area under MTF curve covers 82.466% of the image space, and has a value of 21.8 cycles/mm.