This paper conducted experimental studies on the damping and mechanical properties of carbon nanotube-nanosilica-cement composite materials with different carbon nanotube contents. The damping and mechanical propertie...This paper conducted experimental studies on the damping and mechanical properties of carbon nanotube-nanosilica-cement composite materials with different carbon nanotube contents. The damping and mechanical properties enhancement mechanisms were analyzed and compared through the porosity structure test, XRD analysis, and scanning electron microscope observation. The results show that the introduction of nanosilica significantly improves the dispersion of carbon nanotubes in the cement matrix. At the same time, the addition of nanosilica not only effectively reduces the critical pore size and average pore size of the cement composite material, but also exhibits good synergistic effects with carbon nanotubes, which can significantly optimize the pore structure. Finally, a rationalization suggestion for the co-doping of nanosilica and carbon nanotubes was given to achieve a significant increase in the flexural strength, compressive strength and loss factor of cement-based materials.展开更多
The Context: Aims: To evaluate the biocompatibility and in vitro genotoxicity of a non-copper nano silica polymer modified composite for filtering-type intra-vas devices. Settings and Design: Academic research laborat...The Context: Aims: To evaluate the biocompatibility and in vitro genotoxicity of a non-copper nano silica polymer modified composite for filtering-type intra-vas devices. Settings and Design: Academic research laboratory, Huazhong University of Science and Technology. Prospective experimental study. Methods and Material: Non-copper nano silica polymer modified composite rods were implanted into the back muscle of rabbits for biocompatibility evaluation. Comet assay was applied to the determination of DNA damage, while, Mutagenic activity was tested by means of Ames test using Salmonella typhimurium TA98 and TA 100 tester strains with and without metabolic activation. Statistical analysis used: qualitative and quantitative data were tested using the Chi-square test and Student’s test. Results: Only mild inflammatory reaction was observed in the surrounding tissues of the implanted nano-silica modified polymer composite in the early implantation stage, which was similar to that of the sham-operated group. The inflammatory reaction was completely disappeared after 12 weeks. No significant DNA damage (P > 0.05) were tested on the nano-silica modified polymer composite in Comet assay. In Ames test, the extracts from non-copper composite did not exert mutagenic effect on the bacterial. Conclusions: The non-copper nano silica modified composite did not exhibit in vitro genotoxicity and obvious inflammation in tissue, it would be a safe biomaterial for further clinical trial.展开更多
Two kinds of poly（vinyl alcohol） （PVA）-silica composites were prepared with different methods. One composite was prepared by directly mixing PVA with 80 nm silica nano-particles which were made from tetraethoxysil...Two kinds of poly（vinyl alcohol） （PVA）-silica composites were prepared with different methods. One composite was prepared by directly mixing PVA with 80 nm silica nano-particles which were made from tetraethoxysilane （TEOS）. The another was obtained by the mixing PVA and hydrolyzed TEOS in the presence of acid-catalyst. The properties of the two PVA/silica hybrids were characterized by means of scanning electron microscopy （SEM）, UV-Visible spectroscopy, solubility tests, limiting oxygen index （LOI） test, tensile test and dynamical mechanical analysis （DMA）, respectively. The results indicate that PVA-TEOS composites （PT for short） display more transparency than PVA-silica nano-particles hybrids （PS for short）. At the same time, The PT composites presented more excellent performance than PS in water resistance, fire resistance and mechanical properties. Moreover, the Tg of PT increased with increasing TEOS content, while that of PS decreased.展开更多
文摘This paper conducted experimental studies on the damping and mechanical properties of carbon nanotube-nanosilica-cement composite materials with different carbon nanotube contents. The damping and mechanical properties enhancement mechanisms were analyzed and compared through the porosity structure test, XRD analysis, and scanning electron microscope observation. The results show that the introduction of nanosilica significantly improves the dispersion of carbon nanotubes in the cement matrix. At the same time, the addition of nanosilica not only effectively reduces the critical pore size and average pore size of the cement composite material, but also exhibits good synergistic effects with carbon nanotubes, which can significantly optimize the pore structure. Finally, a rationalization suggestion for the co-doping of nanosilica and carbon nanotubes was given to achieve a significant increase in the flexural strength, compressive strength and loss factor of cement-based materials.
文摘The Context: Aims: To evaluate the biocompatibility and in vitro genotoxicity of a non-copper nano silica polymer modified composite for filtering-type intra-vas devices. Settings and Design: Academic research laboratory, Huazhong University of Science and Technology. Prospective experimental study. Methods and Material: Non-copper nano silica polymer modified composite rods were implanted into the back muscle of rabbits for biocompatibility evaluation. Comet assay was applied to the determination of DNA damage, while, Mutagenic activity was tested by means of Ames test using Salmonella typhimurium TA98 and TA 100 tester strains with and without metabolic activation. Statistical analysis used: qualitative and quantitative data were tested using the Chi-square test and Student’s test. Results: Only mild inflammatory reaction was observed in the surrounding tissues of the implanted nano-silica modified polymer composite in the early implantation stage, which was similar to that of the sham-operated group. The inflammatory reaction was completely disappeared after 12 weeks. No significant DNA damage (P > 0.05) were tested on the nano-silica modified polymer composite in Comet assay. In Ames test, the extracts from non-copper composite did not exert mutagenic effect on the bacterial. Conclusions: The non-copper nano silica modified composite did not exhibit in vitro genotoxicity and obvious inflammation in tissue, it would be a safe biomaterial for further clinical trial.
基金financially supported by the National Natural Science Foundation of China(No.51173112)the Special Funds for Major Basic Research Projects of China(No.2011CB606006)
文摘Two kinds of poly（vinyl alcohol） （PVA）-silica composites were prepared with different methods. One composite was prepared by directly mixing PVA with 80 nm silica nano-particles which were made from tetraethoxysilane （TEOS）. The another was obtained by the mixing PVA and hydrolyzed TEOS in the presence of acid-catalyst. The properties of the two PVA/silica hybrids were characterized by means of scanning electron microscopy （SEM）, UV-Visible spectroscopy, solubility tests, limiting oxygen index （LOI） test, tensile test and dynamical mechanical analysis （DMA）, respectively. The results indicate that PVA-TEOS composites （PT for short） display more transparency than PVA-silica nano-particles hybrids （PS for short）. At the same time, The PT composites presented more excellent performance than PS in water resistance, fire resistance and mechanical properties. Moreover, the Tg of PT increased with increasing TEOS content, while that of PS decreased.
