The interfacial strength has a significant impact on mechanical properties of diamond composites.In this work,polycrystalline diamonds(PCDs)with medium-entropy alloy(MEA)binders and traditional Co binder were prepared...The interfacial strength has a significant impact on mechanical properties of diamond composites.In this work,polycrystalline diamonds(PCDs)with medium-entropy alloy(MEA)binders and traditional Co binder were prepared at high-pressure and high-temperature.Microstructures and interfacial strengths are carefully characterized using TEM.The results show that diamond particles are well bonded to form skeletons in all PCDs.The interfaces between MEA binders and diamond can be fully coherent.Due to the effect of Cr element and Cr-carbide,the PCD with Co_(50) Ni_(40) Fe_(10)-Cr_(3)C_(2) binder exhibits the highest interfacial bonding strength(1176.6 MPa)and highest fracture toughness(9.97 MPa m^(1/2)).The mechanical analyses indicate that both the interface and diamond skeleton have important effects on the fracture toughness of PCD.The interface with a higher bonding strength,a higher engineering strain and a higher elastic modulus can endure more stress,thereby improving the fracture toughness.展开更多
Objective: To explore the impact of seasonal changes on the T-helper 1(Th1)/T-helper 2(Th2) immune balance of the body in order to elucidate the internal immunological mechanisms underlying seasonal eczema.Methods: Ei...Objective: To explore the impact of seasonal changes on the T-helper 1(Th1)/T-helper 2(Th2) immune balance of the body in order to elucidate the internal immunological mechanisms underlying seasonal eczema.Methods: Eighty 4-week-old male Sprague-Dawley rats were divided into 5 season groups kept in corresponding season simulation environments, and subdivided into the model group and the control group. The Eczema Area and Severity Index(EASI) and scratching frequency were evaluated. The serum levels of immunoglobulin E(IgE), interleukin-2(IL-2), interleukin-12(IL-12), and interferon-gamma(IFN-γ), interleukin-4(IL-4), interleukin-25(IL-25), and interleukin-31(IL-31), and melatonin(MT), as well as the MT receptor(MTR) levels in the spleen, were detected by enzyme-linked immunosorbent assay analysis. The mRNA expression levels of T-bet and GATA3 were detected by quantitative real-time polymerase chain reaction.Results: EASI scores and the scratching frequency of the model group were higher in the long summer than in the other 4 seasons. Meanwhile, the serum levels of IgE and the Th2 cytokines IL-4, IL-25, and IL-31, as well as GATA3 mRNA expression levels, were high during the long summer in both groups. However, the serum levels of the Th1 cytokines IL-2, IL-12, and IFN-γ, as well as MT, MTR, and T-bet mRNA levels, were lower during the long summer. In all 5 seasonal groups(spring, summer, long summer, autumn, and winter), the levels of all immune factors, especially IL-4 and IL-31, were higher in the model group than those in the control group,while the concentrations of MT and MTR were lower.Conclusion: Under long light, hot, and humid conditions in the long summer, the body is more likely to suffer from Th2-dominated immune imbalance. This is the internal mechanism behind the high incidence and severity of eczema during the long summer. MT and MTR play a key role in the seasonal onset of eczema.展开更多
基金financially supported by the Regional Innova-tion and Development Joint Funds of the National Natural Science Foundation of China(No.U20A20236)the Central South Univer-sity Innovation-Driven Research Programme(No.2023CXQD030)the Huaqiao University Engineering Research Center of Brittle Materials Machining(MOE,No.2023IME-002).
文摘The interfacial strength has a significant impact on mechanical properties of diamond composites.In this work,polycrystalline diamonds(PCDs)with medium-entropy alloy(MEA)binders and traditional Co binder were prepared at high-pressure and high-temperature.Microstructures and interfacial strengths are carefully characterized using TEM.The results show that diamond particles are well bonded to form skeletons in all PCDs.The interfaces between MEA binders and diamond can be fully coherent.Due to the effect of Cr element and Cr-carbide,the PCD with Co_(50) Ni_(40) Fe_(10)-Cr_(3)C_(2) binder exhibits the highest interfacial bonding strength(1176.6 MPa)and highest fracture toughness(9.97 MPa m^(1/2)).The mechanical analyses indicate that both the interface and diamond skeleton have important effects on the fracture toughness of PCD.The interface with a higher bonding strength,a higher engineering strain and a higher elastic modulus can endure more stress,thereby improving the fracture toughness.
基金funded by the Fundamental Research Funds for the Central Universities(2020-JYB-ZDGG-016).
文摘Objective: To explore the impact of seasonal changes on the T-helper 1(Th1)/T-helper 2(Th2) immune balance of the body in order to elucidate the internal immunological mechanisms underlying seasonal eczema.Methods: Eighty 4-week-old male Sprague-Dawley rats were divided into 5 season groups kept in corresponding season simulation environments, and subdivided into the model group and the control group. The Eczema Area and Severity Index(EASI) and scratching frequency were evaluated. The serum levels of immunoglobulin E(IgE), interleukin-2(IL-2), interleukin-12(IL-12), and interferon-gamma(IFN-γ), interleukin-4(IL-4), interleukin-25(IL-25), and interleukin-31(IL-31), and melatonin(MT), as well as the MT receptor(MTR) levels in the spleen, were detected by enzyme-linked immunosorbent assay analysis. The mRNA expression levels of T-bet and GATA3 were detected by quantitative real-time polymerase chain reaction.Results: EASI scores and the scratching frequency of the model group were higher in the long summer than in the other 4 seasons. Meanwhile, the serum levels of IgE and the Th2 cytokines IL-4, IL-25, and IL-31, as well as GATA3 mRNA expression levels, were high during the long summer in both groups. However, the serum levels of the Th1 cytokines IL-2, IL-12, and IFN-γ, as well as MT, MTR, and T-bet mRNA levels, were lower during the long summer. In all 5 seasonal groups(spring, summer, long summer, autumn, and winter), the levels of all immune factors, especially IL-4 and IL-31, were higher in the model group than those in the control group,while the concentrations of MT and MTR were lower.Conclusion: Under long light, hot, and humid conditions in the long summer, the body is more likely to suffer from Th2-dominated immune imbalance. This is the internal mechanism behind the high incidence and severity of eczema during the long summer. MT and MTR play a key role in the seasonal onset of eczema.
