Papers by Keyword: Structure Modification

Abstract: Perforated structure is the mechanical weak link of polymer-bonded explosive (PBX). Improving its mechanical property may promote the reliability and effectiveness of weapon system. In this study, strengthening of the perforated PBX plate is conducted by employing surface coating. Digital image correlation (DIC) analysis results suggest that the regional applied epoxy coating layer is able to improve the mechanical properties of the plate. By confining the deformation and releasing the stress concentration around the perforation, the coating layer enhances the load carrying ability and energy dissipation capacity of the plate significantly. This investigation may provide a convenient and effective structure modification method for energetic material, and at the same time, lay foundation to the performance optimization of weapon system.

Abstract: Six compounds were synthesized from the lanostane-type tetracyclic triterpenoid of trametenolic acid B with the aim of obtaining more active compounds, which were characterized by NMR, IR, ESI-MS and elemental analysis. Their cytotoxic activities were evaluated against the breast cancer cell line MD-AMB-231. The compound 3b exhibited the best anti-proliferative effect than trametenolic acid B and other derivatives with the IC50 of 17.78 µM.

Abstract: Martensitic transformations are first order solid state phase transitions and occur in the materials on cooling from high temperature. Shape memory effect is an unusual property exhibited by certain alloy systems, and based on martensitic transformation. The shape memory property is characterized by the recoverability of previously defined shape or dimension when they are subjected to variation of temperature. The shape memory effect is facilitated by martensitic transformation, and shape memory properties are intimately related to the microstructures of the materials. Martensitic transformations occur as martensite variant with the cooperative movement of atoms on {110}_β - type plane of austenite matrix. Martensitic transformations have diffusionless character, and the atomic movement is confined to interatomic lengths in the materials. The basic factors which govern the martensitic transformation are Bain distortion and homogeneous shears. Copper based alloys exhibit this property in metastable β-phase field.

Abstract: Carbon foams were prepared by a polymer sponge replication process and their microwave absorbing properties were investigated. The electric conductivity of carbon foam has a direct effect on its microwave absorbing property, as the carbon foam with a medium electric conductivity of 0.46S/m has got a relatively excellent microwave absorbing property and demonstrated a characteristic of broadband absorption. Some structure modification has been made on carbon foams to fruther imrove their microwave absorbing performance. The result shows that making slots, especially gradient slots on the surface of carbon foams can greatly improve their microwave absorbing properties, while the reflection coefficients for a three-layered carbon foam structure exceeds -10dB with the combination effect of multilayer structure design and parameters gradient variatioin in the whole frequency range of 2.6-18GHz, which is usually to be considered as the practical application standard for microwave absorbing materials.