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Welded joints in naval ship hull structures are weak areas under explosive load, but there are relatively few studies investigating the failure characteristics of welded joints through dynamic fracture and explosion tests. In order to explore and predict the failure characteristics of welded joints under explosive load, instrumented Charpy impact tests, explosion tests, and numerical simulations were carried out. The dynamic fracture toughness of ultra-high strength ship hull structural steel welded joints was obtained, and the dynamic stress intensity factors, together with the correlation between stress wave and crack propagation at different positions, were acquired. The results showed that the stress state at the crack tip of a Charpy impact specimen was consistent with that of a welded joint under explosive loads, and the crack initiated when the dynamic stress intensity factor exceeded the dynamic fracture toughness. The results indicated that the dynamic fracture toughness obtained by instrumented Charpy impact tests could be used to predict the crack initiation characteristics of welded structures under explosive load, and the stress wave at the crack tip was basically perpendicular to the crack propagation surface and promoted the rapid propagation of cracks. [ABSTRACT FROM AUTHOR]

CdZnTe crystals are widely used as epitaxial substrates for HgCdTe thin films for infrared detectors and in the fabrication of room temperature nuclear radiation detectors. During crystal growth, the interface shape is closely related to the heat state. Combined with the numerical simulation technique to control the temperature field distribution during CdZnTe crystal growth, the crystal growth procedure of micro-convex solidification interface by vertical Bridgman method and vertical gradient freeze method were designed, and the single crystal rate of CdZnTe crystals was analyzed according to the actual crystal growth experiments. The distribution spectrum of Zn components in the longitudinal section of CdZnTe crystals with equal diameters was obtained by photoluminescence spectroscopy for compositional testing in order to investigate the relationship between the temperature field distribution at the solid-liquid interface and the macroscopic segregation behavior of Zn components. It is found that the temperature gradient distribution on both sides of the solid-liquid interface significantly influences the shape selection and stability of the solidification interface during the crystal growth process, and a larger temperature gradient on the solid-phase side contributes helps to achieve stable crystal growth at the convex interface, thereby increasing the likelihood of growing single crystals. [ABSTRACT FROM AUTHOR]

To solve the shortage of austenite phase precipitation caused by nitrogen loss in the welding process of UNS S2205 duplex stainless steel (DSS), shielding gas nitriding was investigated by adding different N2 contents in Ar shielding gas during the welding process. A good thin-walled pipe butt joint was formed using the pulsed tungsten inert gas (P-TIG) welding method with Ar-N2 shielding gas. High cycle fatigue tests of the weld joints were conducted to study the effect of shielding gas nitriding on the fatigue properties. Fatigue tests at three stress levels of 225 MPa, 270 MPa, and 360 MPa were carried out on the weld joints with different N2 contents, and the fatigue samples were all fractured in the high temperature heat-affected zone (H-HAZ). Within the current process parameters, the fatigue life of the 4 vol.% N2 welded joints was optimal. Fatigue striations appeared in the fatigue crack propagation zone, and the transient fracture zone was similar to the tensile fracture. Under the low-stress level, the area of the crack propagation zone under 4 vol.% N2 was the highest, the tear ridges all expanded around the crack source area, and the fatigue crack propagation zone presented a radial distribution. The proliferation and expansion of dislocations were mainly carried out in the austenite grains, and the dislocation density of the fatigue specimens under 4 vol.% N2 was smaller than that of the Ar specimens. Shielding gas nitriding effectively improved the balance of the two-phase ratio and the hardness of austenite phase, optimized the internal slip system, inhibited the proliferation of dislocations in the austenite phase, and improved the fatigue life of weld joints. [ABSTRACT FROM AUTHOR]

In this report, we applied the TissueFAXS 200 digital pathological analysis system to rapidly and accurately identify neutrophils during regeneration of contused skeletal muscle, and to provide information for follow-up studies on neutrophils to estimate wound age. Rat injury model was established, and skeletal muscle samples were obtained from the control group and contusion groups at 1, 1.5, 2, 3, 4, and 6 h, as well as at 1, 3, 5, and 15 d post-injury (n = 5 per group). The expression of nuclei and neutrophils was detected by hematoxylin and eosin (HE) staining and immunohistochemical (IHC) staining. A total of 20 injury site areas of 0.25 mm2 (0.5 mm × 0.5 mm) were then randomly selected at all time points. A TissueFAXS 200 digital pathological analysis system was used to identify the positive and negative numbers. Knowledge of five professional medical workers were considered the gold standard to measure the false positive rate (FPR), false negative rate (FNR), sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic (ROC) curves. As a result, with a staining area of neutrophils from 8 µm2 to 15 µm2, the FPR was 4.28%–12.14%, the FNR was 12.42%–64.08%, the sensitivity was 35.92%–87.58%, the specificity was 87.86%–95.72%, the Youden index was 0.316–0.754, the accuracy was 82.80%–88.30%, and the AUC was 0.771–0.826. The AUC was largest when the cut-off value of the staining area was 12 µm2. Our results show that this software-based method is more accurate than the human eye in evaluating neutrophil infiltration. Based on the sensitivity and specificity, neutrophils can be accurately identified during regeneration of contused skeletal muscle. The TissueFAXS 200 digital pathological analysis system can also be used to optimize conditions for different cell types under various injury conditions to determine the optimal cut-off value of the staining area and provide optimal conditions for further study. Furthermore, it will provide evidence for forensic pathology cases. [ABSTRACT FROM AUTHOR]

Summary: In this work, we report the ab initio numerical simulation investigation on the crystal lattice, electronic structure, optical, and transport properties of pure and C‐doped crystalline hafnium dioxide (c‐HfO2) using FP‐LAPW method. Different exchange correlation functionals like generalized gradient approximation (GGA) of PBE‐sol and Tran and Blaha's modified Becke‐Johnson exchange potential (mBJ) within density functional theory have been used. Two kinds of defects in cubic pure HfO2 have been investigated: one is substitution of Hf atom by C impurity and other substitution of O atom by C impurity in crystalline HfO2. The computed results indicate that impurity energy bands as a result of 2p states of C are found to present in the band gap of c‐HfO2. Few of these bands are present at the conduction band minimum, which results to a noteworthy band gap contraction, and hence electrons close to Fermi level get transferred in doped c‐HfO2. We have also analysed the dielectric function, absorption coefficient, optical conductivity, optical function, electron energy loss, and reflectivity for both pure HfO2 and doped with C. Furthermore, the temperature‐dependent transport properties of C‐doped HfO2 are also discussed in terms of Seeback coefficient, thermal conductivities, electronic conductivities, power factor, and figure of merit in the temperature range 0 to 1200 K. The calculated value of PF for pure HfO2 was found to increase from 0.01 × 1012 WK−2m−1s−1 at 50 K to 1.79 × 1012 WK−2m−1s−1 at 1200 K and for HfO2(1 − x)Cx it was found to increase from 0.06 × 1012 WK−2m−1s−1 at 50 K to 0.25 × 1012 WK−2m−1s−1 at 1200 K. [ABSTRACT FROM AUTHOR]

BACKGROUND: Zinc (Zn) fertilization has been reported to improve the quality and storability of many fruits, but the mechanism had not been systematically studied. In this study, the effect of preharvest 0.2% zinc sulfate (ZnSO4) spray on the storability of longan fruits was investigated. RESULTS: The preharvest ZnSO4 spray did not significantly influence the quality but increased the Zn content in longan pericarp by 12.5‐fold. More importantly, the treatment significantly reduced the rotting rate, pericarp browning, and aril breakdown of longan fruits stored at room temperature and low temperature. Physiological and biochemical results indicated that the treatment resulted in higher water retention capacity and inhibited the degradation of cellulose, pectin, flavonoid, and phenolics of longan pericarp at the late stages of storage. Consistent with these results, the activity of cellulase, polygalacturonase, polyphenol oxidase, and lipoxygenase was significantly inhibited in the ZnSO4‐treated longan pericarp at the late stages of storage. CONCLUSION: Higher Zn content in the ZnSO4‐treated longan pericarp might help to enhance the resistance against microbial infection, inhibit the hydrolysis of cell wall components, and thus effectively protected the cell wall components, maintained the cellular compartmentation, and prevented the phenolics and flavonoid from degradation by browning‐related enzymes. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]