Nano-scale characterization of white layer in broached Inconel 718

The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718. TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale

Study on Differences in the Pathology, T Cell Subsets and Gene Expression in Susceptible and Non-Susceptible Hosts Infected with Schistosoma japonicum

More than 40 kinds of mammals in China are known to be naturally infected with Schistosoma japonicum (S. japonicum); Microtus fortis (M. fortis), a species of vole, is the only mammal in which the schistosomes cannot mature or cause significant pathogenic changes. In the current study, we compared the differences in pathology by Hematoxylin-eosin staining and in changes in the T cell subsets with flow cytometry as well as gene expression using genome oligonucleotide microarrays in the lung and liver, before challenge and 10 days post-infection with schistosomes in a S. japonicum-susceptible mouse model of infection, a non-susceptible rat model and the non-permissive host, M. fortis. The results demonstrated that S. japonicum promoted a more intensive immune response and more pathological lesions in M. fortis and rats than in mice. Hematoxylin-eosin staining revealed that the immune effector cells involved were mainly eosinophilic granulocytes supplemented with heterophilic granulocytes and macrophages. The analysis of splenic T cell subsets showed that CD4+ T cell subsets and the CD4+/CD8+ ratio were increased, while the CD8+ T cell subsets decreased remarkably in rats; whereas the CD8+ T cell subsets were increased, but the CD4+/CD8+ ratio was decreased significantly in mice. The analysis of the pattern of gene expression suggested that some immune-associated genes and apoptosis-inducing genes up-regulated, while some development-associated genes were down-regulated in the infected M. fortis compared to the uninfected controls; the three different hosts have different response mechanisms to schistosome infection. The results of this study will be helpful for identifying the key molecules in the immune response to S. japonicum in M. fortis and for understanding more about the underlying mechanism of the response, as well as for elucidating the interaction between S. japonicum and its hosts

Towards Understanding Change-Supportive Organizational Behaviors in China: An Investigation of the 2015 Chinese National Football Reform

This paper investigates the influences of change recipients’ supportive behaviors toward the national reform in the Chinese football sector. Qualitative data were collected through semi-structured interviews (n=29), which were conducted with change recipients from national and local football associations and commercial football clubs. Drawing on an integrated conceptual framework, the findings suggest that the change-supportive behaviors demonstrated by the change recipients were influenced and incentivised by managerial factors (i.e., management competency, communication channels, participation in decision-making, leaders’ commitment to change, and principal support); and contextual factors (i.e., an amenable football environment and the perceived political pressure to change). Three manifestations of change-supportive behaviors were identified: a) showing understanding of the change but pessimistic about the outcome; b) supporting the change and being willing to take risks; and c) supporting the change and actively seeking alternative solutions

Atomically dispersed quintuple nitrogen and oxygen co-coordinated zirconium on graphene-type substrate for highly efficient oxygen reduction reaction.

A cost-effective and long stability catalyst with decent electrochemical activity would play a crucial role in accelerating applications of metal-air batteries. Here, we report quintuple nitrogen and oxygen co-coordinated Zr sites on graphene (Zr-N/O-C) by using a ball-milling, solid-solution-assisted pyrolysis method. The as-prepared Zr-N/O-C catalyst with 2.93 wt % Zr shows a half-wave potential of 0.910 V, an onset potential of 1.000 V in 0.1 M KOH, impressive durability (95.1% remains after 16,000 s), and long-term stability (5 mV loss over 10,000 cycles). Zn-air batteries with the Zr-N/O-C electrode exhibit a maximum power density of 217.9 mW cm−2 and a high cycling life of over 1,000 h, exceeding the counterpart equipped with a Pt/C benchmark. Theoretical simulations demonstrate that nitrogen and oxygen dual-ligand confinement effectively tunes the d-band center and balances key intermediates binding energy of intrinsic quintuple coordination Zr sites

Analysis of the influence of different initial velocities on dynamic performance of multi-layer hard target penetration process

To determine the overload characteristics of the internal system of a fuze that penetrates multilayer hard targets using different fixed-link structures, a finite element model consisting of two fixed-link structures (a compression screw and a body screw) is adopted in this paper to simulate the penetration process of a three-layer concrete target plate with corresponding initial velocities. The peak amplification coefficient and vibration coefficient are used to analyze the time-domain characteristics of the penetration process signal during segmented analysis. The extracted acceleration signals of the projectile and sensor are processed by fast Fourier transform to obtain the frequency spectrum analysis results. The simulation results show that under the same working conditions, the sensor’s ability to amplify the peak acceleration of the projectile is 17.77% higher for the body screw fixed-link structure, and the average vibration coefficient is also 9.55% higher. Compared with that of the body screw fixed-link structure, the performance of the compression screw fixed-link structure is better under different initial velocity conditions. The initial penetration velocity affects mainly the amplitude of each frequency corresponding to the acceleration signals of the two fixed-link fuze structure projectiles and sensors while having a relatively small influence on the frequency distribution position