High-performance Self-lubricating Ceramic Composites with Laminated-graded Structure

High-performance ceramic composites are potential candidates for the application of wear-resistance components because of their excellent properties. Nevertheless, many problems, such as high friction coefficient of ceramic material and poor mechanical properties of ceramic-matrix self-lubricating composites, limit a wider range of applications of these composites in tribological areas. Therefore, improving high-toughness ceramic-matrix self-lubricating materials for practical applications is significant. This study proposes a new design for ceramic self-lubricating composites to overcome the conflict between their mechanical and tribological properties. Complying with the design principle of bionic and graded composites, two kinds of self-lubricating ceramic composites with laminated-graded structure were prepared, and their mechanical and tribological properties were studied. The results show that this newly developed ceramic composite has achieved satisfactory strength and tribological properties compared with the traditional ceramic self-lubricating composites. The bending strength reached the same level as the properties of general monolithic ceramics. In the temperature range of 25-800 °C, the friction coefficient of composites was less than 0.55, which was about half of that of monolithic ceramics

Ectopic expression of human airway trypsin‐like protease 4 in acute myeloid leukemia promotes cancer cell invasion and tumor growth

Abstract Transmembrane serine proteases have been implicated in the development and progression of solid and hematological cancers. Human airway trypsin‐like protease 4 (HAT‐L4) is a transmembrane serine protease expressed in epithelial cells and exocrine glands. In the skin, HAT‐L4 is important for normal epidermal barrier function. Here, we report an unexpected finding of ectopic HAT‐L4 expression in neutrophils and monocytes from acute myeloid leukemia (AML) patients. Such expression was not detected in bone marrow cells from normal individuals or patients with chronic myeloid leukemia, acute lymphocytic leukemia and chronic lymphocytic leukemia. In AML patients who underwent chemotherapy, persistent HAT‐L4 expression in bone marrow cells was associated with minimal residual disease and poor prognostic outcomes. In culture, silencing HAT‐L4 expression in AML–derived THP‐1 cells by short hairpin RNAs inhibited matrix metalloproteinase‐2 activation and Matrigel invasion. In mouse xenograft models, inhibition of HAT‐L4 expression reduced the proliferation and growth of THP‐1 cell–derived tumors. Our results indicate that ectopic HAT‐L4 expression is a pathological mechanism in AML and that HAT‐L4 may be used as a cell surface marker for AML blast detection and targeting

Vertically Aligned Silicon Nanowire Array Decorated by Ag or Au Nanoparticles as SERS Substrate for Bio-molecular Detection

This review article summerises preparation techniques of vertically aligned silicon nanowire (Si NW) arrays through metal-assisted chemical etching (MacEtch) process and plasmonic nanoparticles (Ag and Au) with the perspective of the fabrication of surface-enhanced Raman scattering (SERS)-active substrates which are highly efficient for bio-molecular detection. At first, basic methods and mechanisms for SERS have been introduced and size and shape effects of the nanoparticles (NPs) on plasmonic vibration have been discussed. Comparative discussions on optical and plasmonic characteristics of Ag and Au NPs have also been presented in this section. Potential techniques for the synthesis of Ag and Au NPs with different sizes and shapes have been reported in the following section. Basic processes and mechanism for the fabrication of vertically aligned Si NW arrays on Si by MacEtch of Si wafer have been discussed. Template-assisted fabrication techniques for the vertically aligned Si NW arrays with controlled diameter and number density have also been reported. Finally, multifarious ways for the fabrication of SERS-active substrates by assembling noble metal NPs onto the NW surface have been discussed and their performance for bio-molecular detection has also been reported