Glass fibre is a random network structure composed of [SiO4] tetrahedra. The structure contains a large number of defects, which act as crack initiation points. Under tensile stress, cracks undergo crack initiation, stable propagation, failure propagation, and fracture, and the stress that begins after unstable propagation is called the critical fracture stress. When the stress is less than the critical value, the crack is subject to the force of chemical bonds during the crack propagation process, and crack arrest occurs. When the stress is greater than the critical value, the glass fibre will undergo destructive fracture. In this paper, long-term tensile tests were carried out on glass fibre and a glass fibre composite under different constant tensile stress conditions. The fracture times of the glass fibre and glass fibre composite under different tensile stresses were obtained, the critical fracture stress of glass fibre was inferred, and the fracture mechanism was explained. 相似文献
The lithiation of 5,5′‐dibromo‐2,2′‐bithiophene with one equivalent of an alkyllithium such as n‐BuLi or s‐BuLi was studied by varying the residence time in flow microreactors. With a short residence time, the product 2,2′‐bithiophene (3) derived from dilithiation was obtained preferentially and a significant amount of the starting material 5,5′‐dibromo‐2,2′‐bithiophene remained unchanged. An increase in the residence time caused a higher yield of the product 5‐bromo‐2,2′‐bithiophene derived from monolithiation with expense in the yields of 2,2′‐bithiophene and 5,5′‐dibromo‐2,2′‐bithiophene. The lithiation using MeLi gave the product 5‐bromo‐2,2′‐bithiophene preferentially even with a very short residence time. 相似文献
Nacre-inspired laminated composites have been proven to possess a unique combination of strength and toughness. In this study, we fabricated nacre-mimetic Cu/TiC composites via unidirectional freezing of aqueous TiC slurries containing different amounts of NiO additives, followed by ice sublimation, carbothermal reduction of NiO to Ni during sintering and then gas-pressure infiltration of the Cu melt. The introduction of Ni greatly facilitated the densification of ceramic lamellae and enhanced the interfacial bonding between Cu and TiC. The resultant composites displayed outstanding damage tolerance and anisotropic electrical conductivities. Specifically, for an ~31?vol% TiC–Cu composite containing 24?wt% Ni in the ceramic lamellae (based on the TiC content), a fracture toughness (KJc) of 72.5?±?1.0?MPa·m1/2, work of fracture of 53.4?±?3.5?kJ/m2, bending strength of 725?±?11?MPa and longitudinal electrical conductivity of 22.7?MS/m (~60% of the Cu matrix) were achieved, which were approx. 81%, 536%, 122% and 97% higher than those of the Ni-free composite, respectively. Noticeable toughening was demonstrated to be a consequence of multiple cracking, plastic deformation and uncracked-ligament bridging of the metal layers, as well as crack deflection and blunting. On the other hand, significant strengthening resulted from tailoring the microstructures in the ceramic layers and at the Cu/TiC interface as a result of Ni doping. We believe that the facile strategy adopted herein provides an effective way to solve the problems of wetting and bonding related to metal infiltration and can be readily extended to the preparation of other nacre-inspired metal?ceramic composites. 相似文献
Triple-negative breast cancer (TNBC) is one type of the most aggressive breast cancers with poor prognosis. It is of great urgency to develop new therapeutics for treating TNBC. Based on current treatment guideline and genetic information of TNBC, a combinational therapy platform integrating chemotherapy drugs and mRNA encoding tumor suppressor proteins may become an efficacious strategy. In this study, we developed paclitaxel amino lipid (PAL) derived nanoparticles (NPs) to incorporate both chemotherapy drugs and P53 mRNA. The PAL P53 mRNA NPs showed superior properties compared to Abraxane® and Lipusu® used in the clinic including high paclitaxel loading capacity (24 wt.%, calculated by paclitaxel in PAL), PAL encapsulation efficiency (94.7% ± 6.8%) and mRNA encapsulation efficiency (88.7% ± 0.7%). Meanwhile, these NPs displayed synergetic cytotoxicity of paclitaxel and P53 mRNA in cultured TNBC cells. More importantly, we demonstrated in vivo anti-tumor efficacy of PAL P53 mRNA NPs in an orthotopic TNBC mouse model. Overall, these chemotherapy drugs derived mRNA NPs provide a new platform to integrate chemotherapy and personalized medicine using tumor genetic information, and therefore represent a promising approach for TNBC treatment.
To design a clinically translatable nanomedicine for photodynamic theranostics, the ingredients should be carefully considered. A high content of nanocarriers may cause extra toxicity in metabolism, and multiple theranostic agents would complicate the preparation process. These issues would be of less concern if the nanocarrier itself has most of the theranostic functions. In this work, a poly(ethylene glycol)‐boron dipyrromethene amphiphile (PEG‐F54‐BODIPY) with 54 fluorine‐19 (19F) is synthesized and employed to emulsify perfluorohexane (PFH) into a theranostic nanoemulsion (PFH@PEG‐F54‐BODIPY). The as‐prepared PFH@PEG‐F54‐BODIPY can perform architecture‐dependent fluorescence/photoacoustic/19F magnetic resonance multimodal imaging, providing more information about the in vivo structure evolution of nanomedicine. Importantly, this nanoemulsion significantly enhances the therapeutic effect of BODIPY through both the high oxygen dissolving capability and less self‐quenching of BODIPY molecules. More interestingly, PFH@PEG‐F54‐BODIPY shows high level of tumor accumulation and long tumor retention time, allowing a repeated light irradiation after a single‐dose intravenous injection. The “all‐in‐one” photodynamic theranostic nanoemulsion has simple composition, remarkable theranostic efficacy, and novel treatment pattern, and thus presents an intriguing avenue to developing clinically translatable theranostic agents. 相似文献
Neural Computing and Applications - For a class of nonlinear multi-agent systems under switching topologies with disturbances, we propose a distributed H∞ consensus control protocol based on... 相似文献
Granular Matter - A method to identify the parameters of rolling resistance between particles in the discrete element method is proposed in this paper. Experiments revealed that a free rolling... 相似文献