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The strength, toughness, and fatigue crack growth (FCG) resistance of high‐strength steels are the key performance indexes concerned in the material selection of engineering components. It is considered that the FCG resistance of high‐strength steels can be optimized by simultaneous strengthening and toughening. In order to make clear whether the above view is correct or not, the strength–toughness combination and FCG resistance of AISI 4340 steel under different heat treatments are investigated and compared with those of 18Ni maraging steel in the present study. Meanwhile, the major fatigue damage mechanism of the AISI 4340 steel is analyzed and discussed. It is found that the FCG resistance of AISI 4340 steel enhances rapidly at first and then remains approximately the same with the decrement of strength (the improvement of toughness). Moreover, it is detected that simultaneously upgrading the strength and toughness of high‐strength steels cannot improve the FCG resistance. Finally, it is believed that the microscopic fatigue damage mechanism is the major factor determining the FCG resistance rather than the macroscopic strength–toughness combination, and the factors affecting the FCG resistance of AISI 4340 steel are mainly the pre‐existing dislocations and carbide precipitates. [ABSTRACT FROM AUTHOR]

Herein, the high‐cycle fatigue behaviors of 18Ni maraging steel with different tensile strength in the stress ratio range from 0.1 to 0.5 are investigated, and compared with those at the stress ratio of −1. It is found that the relationship between the fatigue strength at the stress ratios of −1 and 0.1 and tensile strength is nonmonotonic, while the fatigue strength at the stress ratio of 0.5 improves as the tensile strength heightens. The tensile strength corresponding to the optimal fatigue strength state would change with the variation of the stress ratio, which is related to the alteration of key factors affecting the fatigue damage. Moreover, it is found that the Walker equation: σaR = σ−1 ⋅ [(1 − R)/2]β gives reasonable results for the influence of stress ratio on the fatigue strength of 18Ni maraging steel. [ABSTRACT FROM AUTHOR]

The tensile strength and fracture toughness of softwood and hardwood are measured by the Boundary Effect Model (BEM). The experimental results of single-edge notched three-point bending tests indicate that the BEM is an appropriate method to estimate the fracture toughness of the present fibrous and porous woods. In softwood with alternating earlywood and latewood layers, the variation in the volume percentage of different layers in a small range has no obvious influence on the mechanical properties of the materials. In contrast, the hardwood presents much higher tensile strength and fracture toughness simultaneously due to its complicated structure with crossed arrangement of the fibers and rays and big vessels diffused in the fibers. The present research findings are expected to provide a fundamental insight into the design of high-performance bionic materials with a highly fibrous and porous structure. [ABSTRACT FROM AUTHOR]

The optical band positions (or crystal field energy levels) of manganese (IV) ions in trigonal barium titanium hexafluoride and barium silicon hexafluoride crystals are computed from the full diagonalization (of energy matrix) method founded on the two-spin-orbit-parameter model which consists of the effects from both the spin-orbit parameters of dn ion and ligand ions. The computed results are in rational agreement with the experimental values. It is found that the large difference of first excited state splitting ΔE (2E) between the manganese (IV)-doped barium titanium hexafluoride and barium silicon hexafluoride crystals is owing mainly to the great difference of trigonal distortion between the fluorine octahedral clusters in the two host crystals. [ABSTRACT FROM AUTHOR]

In this article, the calculations with the high-order perturbation formulas founded on the two-spin-orbit-parameter (of d n ion and that of ligand) model are performed for the spin-Hamiltonian parameters (zero-field splitting D and g factors g // , g ⊥ ) of the tetragonal Co 2+ tetrahedral centers in Y 3 Al 5 O 12 and Y 3 Ga 5 O 12 crystals. The calculated results by using only one adjustable parameter are comparable with the experimental values. The impurity-caused angular distortions in the Co 2+ centers in both crystals are also evaluated. The results are discussed. [ABSTRACT FROM AUTHOR]

To investigate the effect of the spacers of S-/O-bridged dipyridylamides on the structures of Co(II)/Zn(II) complexes, [Co(L1)(chda)]·1.5H2O (CP1), [Co(L2)(chda)] (CP2), [Zn(L1)(hip)]·DMA·2H2O (CP3), and [Zn(L2)(hip)]·2.8H2O (CP4) [L1 = N,N′-bis(pyridine-3-yl)thiophene-2,5-dicarboxamide, H2chda = trans-1,4-cyclohexanedicarboxylic acid, L2 = N,N′-bis(pyridine-3-yl)-4,4′-oxybis(benzoic) dicarboxamide, H2hip = 5-hydroxyisophthalic acid, DMA = N,N-dimethylacetamide], have been solvothermally synthesized. X-ray single-crystal diffraction shows that CP1 is a 2-D 3,5-connected network based on Co-L1 linear chains and (Co-chda)2 double chains. CP2 features a 1-D structure derived from 1-D wave-like (Co-chda)2 double chains decorated by terminal L2 ligands. CP3 and CP4 show wave-like (4,4) networks constructed by 1-D Zn-L1 zigzag and Zn-hip zigzag (for CP3)/linear (for CP4) chains. The effect of the spacers of S-/O-bridged dipyridylamides on the structures of the title complexes was discussed. Electrochemical behaviors of CP1-CP2 and solid-state luminescent properties of CP3-CP4 were studied. The luminescence investigations show that CP3 and CP4 are recycled fluorescent probes for environmentally relevant Fe3+ ions. The photocatalytic properties for the degradation of methylene blue (MB) under ultraviolet light irradiation of CP3-CP4 and the recyclable materials after fluorescent sensing Fe3+ ions (named CP3@Fe3+ and CP4@Fe3+) have also been investigated. [ABSTRACT FROM AUTHOR]

To explore the micro-mechanism for the size effect of the mechanical behavior of metallic crystals, the tensile and fatigue behavior of [ABSTRACT FROM AUTHOR]

In order to achieve a controllable spin-polarized source, we have applied a transverse electric field to a spin filter based on a novel magnetic nanostructure with zero average magnetic field. We have analytically calculated the transmission coefficient, conductance and spin polarization for electrons to transit the device in the presence of a transverse electric field. The results demonstrate that the transmission, the conductance and the spin polarization vary sensitively with the electric field. It is shown that the performance of the spin filter can be manipulated expediently by adjusting the transverse electric field. Thus, the spin filter can be utilized as an electrically controllable spin-polarized source for spintronics applications. [ABSTRACT FROM AUTHOR]

The microstructures of Veined rapa whelk shell were characterized, and a series of compression tests were carried out on the shell with the compressive loading direction making different angles (0°, 30°, 60° and 90°) with the shell spiral lines. Weibull analysis of the experiment results shows that the compressive strength is generally the highest for the sample with 0°-orientation but the lowest for that with 60°-orientation, which means that the strength shows an obvious anisotropy and the strongest orientation represents the direction parallel to the spiral lines of the shell. Such a phenomenon is closely related to the distinctive microscopic arrangements of different-order aragonite lamellae. The interfaces of different-level lamellae in the adjacent macro-layers yield effects on the mechanical behavior of the shell in a coordinated fashion. [ABSTRACT FROM AUTHOR]

The microstructures and mechanical properties of Clinocardium californiense shell were investigated in relation to the different parts of shell. It is found that the shell can be divided into three parts, that is, the dorsal side, body part, and marginal side based on the variation of microstructures along the longitudinal cross section. Specifically, all areas exhibit a cross-lamellar structure on the dorsal side, and a hierarchical structure comprising three layers including inner (with a cross-lamellar structure), middle (with a complex cross-lamellar structure), and outer (with a prismatic structure) layers was observed on the body part, whereas on the marginal side, the orientation of aragonite sheets shows an obvious deflection. The structural architecture, the dimensions of different-order lamellae in the same kind of structure and the orientation between the indenting direction and aragonite sheet all contribute to the unique mechanical properties of this shell. It is also found that a low value of the ratio of hardness-to-Young's modulus ( H/ E) corresponds to an improved indentation toughness. The middle layer with the densest and most complicated structure on the body part shows the lowest H/ E ratio and the highest hardness and Young's modulus. [ABSTRACT FROM AUTHOR]

Aim: To verify if detailed analysis of temporal enhancement patterns on contrast enhanced ultrasound (CEUS) may help differentiate intrahepatic cholangiocarcinoma (ICC) from hepatocellular carcinoma (HCC) in cirrhosis. Methods: Thirty three ICC and fifty HCC in cirrhosis were enrolled in this study. The contrast kinetics of ICC and HCC was analyzed and compared. Results: Statistical analysis did not reveal significant difference between ICC and HCC in the time of contrast first appearance and arterial peak maximum time. ICC displayed much earlier washout than that of HCC (47.93±26.45 seconds vs 90.86±31.26 seconds) in the portal phase, and most ICC (87.9%) showed washout before 60 seconds than HCC (16.0%). Much more ICC (78.8%) revealed marked washout than HCC (12.0%) while most HCC (88.0%) showed mild washout or no washout in late part of the portal phase (90–120 seconds). Twenty six out of thirty three ICC (78.8%) demonstrated both early washout(<60seconds) and marked washout in late part of the portal phase, whereas, only six of fifty HCC (12.0%)showed these temporal enhancement features (p = 0.000).When both early washout and marked washout in the portal phase are taken as diagnostic criterion for ICC, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 78.8%,88.0%,81.3%,86.3%,and 84.3% respectively by CEUS. Conclusions: Analysis of detailed temporal enhancement features on CEUS is helpful differentiate ICC from HCC in cirrhosis.If a nodule in cirrhotic liver displays hyper-enhancement in the arterial phase followed by early and marked washout in the portal phase, the nodule is highly suspicious of ICC rather than HCC. [ABSTRACT FROM AUTHOR]

Abstract: The effect of short-term pre-annealing treatment on the compressive deformation and damage behavior of ultrafine-grained (UFG) copper produced by equal channel angular pressing (ECAP) has been studied by mechanical tests and microstructural observations. It is found that a controlled 10-min pre-annealing treatment on the UFG copper below the recrystallization temperature can result obviously in a higher strength (higher flow stress level) and a higher flow stability (lower stress softening rate) under uniaxial compression, as compared to the case of as-ECAPed sample. Observations of surface and interior deformation damage features indicate that, compared to the as-ECAPed copper sample, the pre-annealed ECAPed copper at less than recrystallization temperature may exhibit a better compressive plastic deformation capacity, namely, the destructive deformation morphology of large-scale shear bands normally observed in compressed as-produced UFG copper sample would not appear in compressed pre-annealed sample, except for a relatively smooth surface morphology featuring some ‘step’ reliefs with a few discontinuous shear bands and non-propagation voids. Finally, the deformation mechanism of different kinds of severe plastic deformation (SPD) processed UFG materials as well as their pre-annealing effects are further discussed, and a general rule is summarized as follows: an appropriate selection of pre-annealing temperature and annealing time is needed for improving both strength and ductility of SPDed materials with a microstructure comprising equiaxed grains and well-defined grain boundaries. [Copyright &y& Elsevier]

Background and Aims: Cancer cells are thought to possess immune evasion properties due to FasL overexpression in many types of human tumors. In the present study, we set out to investigate the role of MAPK-ERK pathway in 67-kDa laminin receptor induced FasL expression and FasL-mediated apoptosis in human cholangiocarcinoma cells.Methods: The expression of FasL and its promoter activity in cultured cholangiocarcinoma cells were examined after treatment with laminin or transfection with plasmids containing siRNA targeted to 67-kDa laminin receptor. The effects of MAPK-ERK cascade inhibitor and c-Myc inhibition by siRNA on 67-kDa laminin receptor-induced FasL expression were determined. Apoptosis assay was performed to analyze the apoptosis of lymphocytes cocultured with cholangiocarcinoma cells treated with or without MAPK-ERK cascade inhibitor.Results: Our results revealed that the specific MAPK-ERK cascade inhibitor, PD98059, significantly attenuated phosphorylation of c-Myc on Ser-62 and FasL upregulation in QBC-939 cells and these cells showed decreased cytotoxicity against Fas-sensitive Jurkat T cells. A luciferase reporter assay revealed that FasL promoter activity was significantly reduced in cells treated with PD98059 or transfected with c-Myc siRNA.Conclusions: Based on these results, we conclude that 67LR induces FasL expression and cytotoxicity against Fas-sensitive Jurkat T cells in human cholangiocarcinoma cells through the phosphorylation of c-Myc on Ser-62 and the subsequent activation of the FasL promoter through the ERK pathway. [ABSTRACT FROM AUTHOR]

The work-hardening behavior of Cu–Ni alloys with high stacking-fault energies (SFEs) is experimentally investigated under uniaxial compression. It is found that, with the increase of Ni content (or short-range clustering, SRC), the flow stress of Cu–Ni alloys is significantly increased, which is mainly attributed to an enhanced contribution of work-hardening. An unexpected multistage (including Stages A, B, and C) work-hardening process was found in this alloy, and such a work-hardening behavior is essentially related to the existence of SRC structures in alloys. Specifically, during deformation in Stage B (within the strain range of 0.04–0.07), the forming tendency to planar-slip dislocation structures becomes enhanced with an increase of SRC content (namely, increase of Ni content), leading to the occurrence of work-hardening rate recovery in the Cu–20at.% Ni alloy. In short, increasing SRC in the Cu–Ni alloy can trigger an unexpected multistage work-hardening process, and thus improve its work-hardening capacity. [ABSTRACT FROM AUTHOR]

Abstract: The structure and mechanical behavior of Saxidomus purpuratus bivalve shell were investigated. XRD results show that the only form of calcium carbonate present in the shell is aragonite. The inner and middle layers have a cross-lamellar structure, while the outer layer has porosity and does not have tiles, but instead has ‘blocky’ regions. The hardness of middle and inner layer are close in both plane view and cross section, but the hardness of outer layer is significantly less, especially in the plane view. The compressive strengths with loading along the three orientations were established and significant differences were found. The Weibull strength at 50% of the probability of failure varies between 59 and 148MPa and is dependent on the loading orientation and in condition of shell (dry vs. hydrated). These differences are interpreted in terms of the anisotropic structure and coarser structure of the external layer. [Copyright &y& Elsevier]

Abstract: Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver, and patients who are diagnosed with this tumor typically have a poor prognosis. The suppressive effects of CD4+FoxP3+ regulatory T cells on antitumor immune response in HCC have been studied in great detail. CD8+FoxP3+ regulatory T cells have recently been detected in tumors; however, the role of CD8+FoxP3+ regulatory T cells in HCC is still unknown. Here, the frequency and phenotype of CD8+FoxP3+ regulatory T cells were analyzed by multicolor flow cytometry in liver of HCC patients and healthy donors. We observed that the percentage of these cells in HCC patients was significantly higher than that observed in healthy control donors (p = 0.0155); their phenotype was close to that of CD4+ regulatory T cells. Furthermore, we show that CD8+FoxP3+ regulatory T cells are activated and act as effector memory cells (EM, CD45RA−CCR7−CD27+/−CD28+). Most importantly, a higher percentage of intrahepatic CD8+FoxP3+ regulatory T cells was found in patients with advanced HCC than in those with early HCC in terms of tumor-node-metastasis (TNM) stage (stage I vs III, p = 0.0007). These data suggest that CD8+FoxP3+ regulatory T cells may contribute to HCC immune escape and disease progression. [Copyright &y& Elsevier]

Abstract: The relationships between epithelial-to-mesenchymal transition (EMT), hepatitis B virus X protein (HBx), and the non-receptor tyrosine kinase c-Src were investigated. The HBx gene transfected SMMC-7721 cells underwent morphological changes from a classic epithelial morphology to a spindle-like shape. The HBx transfection increased the invasive potential of these cells. When the transfected cells were exposed to the c-Src kinase inhibitor PP2, the cells recovered their original epithelial morphology and the mRNA and protein expression of epithelial and mesenchymal markers returned to the parental cell levels. Our data suggest that activated c-Src played a critical role in the HBx-induced EMT of SMMC-7721 cells. [Copyright &y& Elsevier]

Background: Ischemia-reperfusion injury (IRI) is responsible for primary liver dysfunction and failure after transplantation. The mitochondrial pathway appears to be involved in liver ischemia-reperfusion injury. Mitochondrial ATP-sensitive K (mitoKATP) channels play a central role in protecting the heart from injury in ischemic preconditioning. The selective mitoKATP channel agonist diazoxide potently reduced mitochondrial injury by preventing cytochrome c loss from the intermembrane space. Therefore, this study sought to determine whether diazoxide can attenuate ischemia-reperfusion injury induced by orthotopic liver transplantation (OLT) in mice. Furthermore, it was found that up-regulation of the Bcl-2 gene is a mechanism of diazoxide cytoprotection. Materials and Methods: Donors were treated with diazoxide, Bcl-2 siRNA, or diazoxide + Bcl-2 siRNA and vehicle 10 min or 24 h before liver harvesting. Liver grafts were then orthotopically transplanted into their corresponding recipients. Results: Liver injury, as judged by transaminase level and histologic examination, was significantly lower in the diazoxide group compared with vehicle controls. The percentage of apoptotic cells and the amount of cytochrome c in the cytosol 6 h after transplant were also markedly reduced in diazoxide-treated grafts compared with vehicle-treated controls. Diazoxide notably up-regulated expression of Bcl-2, while siRNA knockdown of Bcl-2 abolished the cytoprotective effects of diazoxide. Conclusions: Diazoxide attenuated graft injury after mouse liver transplantation. One mechanism of diazoxide protection involves the induction of Bcl-2, an anti-apoptotic protein. Diazoxide might be useful clinically in hepatic surgery and transplantation. [ABSTRACT FROM AUTHOR]

The structural and electronic properties of interfaces play an important role in the stability and functionality of solar cell devices. Experiments indicate that the SnO 2 /perovskite interfaces always show superior electron transport efficiency and high structural stability even though there exists a larger lattice mismatch. Aiming at solving the puzzles, we have performed density-functional theory calculations to investigate the electronic characteristics of the SnO 2 /perovskite interfaces with various stresses and defects. The results prove that the PbI 2 /SnO 2 interfaces have better structural stability and superior characteristics for the electron transport. The tensile stress could move the conduction band minimum (CBM) of CH 3 NH 3 PbI 3 upward, while the compressive stress could move the CBM of SnO 2 downward. By taking into account the stress effect, the CBM offset is 0.07 eV at the PbI 2 /SnO 2 interface and 0.28 eV at the MAI/SnO 2 interface. Moreover, our calculations classify V I and I i at the PbI 2 /SnO 2 interface and Sn-I, I i and Sn i at the MAI/SnO 2 interface as harmful defects. The I i defects are the most easily formed harmful defects and should be avoided at both interfaces. The calculated results are in agreement with the available experimental observations. The present work provides a theoretical basis for improving the stability and photovoltaic performance of the perovskite solar cells., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

As biological ceramic composites, mollusk shells exhibit an excellent strength-toughness combination that should be dependent on aragonite/organic matrix interfaces. The mechanical properties and fracture mechanisms of the nacreous structure in the Cristaria plicata ( C. plicata ) shell and crossed-lamellar structures in the Cymbiola nobilis ( C. nobilis ) shell were investigated, focusing on the critical role of the organic matrix/aragonite interface bonding that can be adjusted by heat treatments. It is found that heat treatments have a negative impact on the fracture behavior of the nacreous structure in the C. plicata shell, and both the bending and shear properties decrease with increasing heat-treatment temperature because of the loss of water and organic matrix. In contrast, for the crossed-lamellar structure in C. nobilis shell, the water loss in heat treatment slightly decreases its bending properties. When the organic matrix is melted after an appropriate heat treatment at 300°C for 15 min, its bending properties can be greatly enhanced; in this case, remarkable toughening mechanisms involving crack deflection and the fiber pull-out are exhibited, although the interfacial bonding strength reduces. Therefore, an appropriate heat treatment would bring about a positive impact on the fracture behavior of crossed-lamellar structure in the C. nobilis shell. The major research findings have provided an important inspiration that the inducement of moderately weak interfaces rather than all strong interfaces might enhance the comprehensive mechanical properties of fiber-reinforced ceramic composites.

Mollusk shells generally consist of several macro-layers with different microstructures. To explore the specific role that different macro-layers play in the overall mechanical properties of shells, the microstructures, hardness distribution, and three-point bending behavior in the deep-sea Nautilus shell were investigated. It is found that the shell presents a hierarchical structure comprising three layers in thickness, that is, the outer, middle, and inner layers, which exhibit homogeneous, prismatic, and nacreous structures, respectively. Among them, the homogeneous structure in the outer layer is harder, which is beneficial for the shell to enhance resistance to wear and perforation. Furthermore, both the bending strength and fracture energy for group Up (loading from outer to inner surfaces) are far higher than those for group Down (loading from inner to outer surfaces), indicating that the inner nacreous layer is not only stronger but also tougher. Cracks tend to deflect at the interfaces in nacreous structure, and nacreous structure is thereby more resistant to breakage. Hence, the nacreous structure in the inner layer could protect the shell from breaking catastrophically in the deep sea with high pressure. In brief, the combination of a harder outside layer and a tougher inside layer provides an effective protective structure for the deep-sea shell, and the excellent environment adaptability of Nautilus shell can thus be interpreted in terms of its ingenious microstructure arrangement.