In this work, patterned macropores with a diameter larger than 100 μm were introduced to pristine three-dimensional (3D) nanofibrous bacterial cellulose (BC) scaffolds by using the infrared laser micromachining techn...In this work, patterned macropores with a diameter larger than 100 μm were introduced to pristine three-dimensional (3D) nanofibrous bacterial cellulose (BC) scaffolds by using the infrared laser micromachining technique in an attempt to create an in vitro model for the culture of breast cancer cells. The morphology, pore structure, and mechanical performance of the obtained patterned macroporous BC (PM-BC) scaffolds were characterized by scanning electron microscopy (SEM), mercury intrusion porosimeter, and mechanical testing. A human breast cancer cell (MDA-MB-231) line was cultured onto the PM-BC scaffolds to investigate the role of macropores in the control of cancer cell behavior. MTT assay, SEM, and hematoxylin and eosin (H&E) staining were employed to determine cell adhesion, growth, proliferation, and infiltration. The PM-BC scaffolds were found to be able to promote cellular adhesion and proliferation on the scaffolds, and further to allow for cell infiltration into the PM-BC scaffolds. The results demonstrated that BC scaffolds with laser-patterned macropores were promising for the in vitro 3D culture of breast cancer cells.展开更多
Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3par...Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3particleswithsizesintherange5to200 μmonapin-on-flattribo-testerunderdryreciprocatingsliding conditions at room temperature. Based on the examined worn surface characteristics of both PTFE and 316L stainless steel (as a counterpart) and the analyzed coefficient of friction (COF) evolutions, the wear mechanism and particle size effect have been explored in detail. The results demonstrate that the abrasive size is the main contributing factor, which can drastically impact the wear mechanism and tribological properties of tribo-pairs. The COF exhibits different evolution characteristics (trends) for different abrasive sizes. For moderate particle sizes, the COF trends become more complicated and the most evident wear of the metallic counterpart is evident. The activity behaviors of abrasives are dominated by the particle size. Particles can becomes embedded in one of the tribo-pair materials to plough-cut the counterpart, thus causing two-body abrasive wear. The abrasives can also behave as free rolling bodies, which play the role of third body to realize three-body "PTFE-abrasive-316L"abrasion. When abrasives are involved in the wear process, both the wear rate and COF of the metallic counterpart increase, but the material removal rate of the PTFE is reduced. The results obtained can offer guidelines regarding the design and protection of seals.展开更多
The control of the morphology of zinc oxide（ZnO） crystals is very important in science and industry.This article reports the influence of bacterial cellulose（BC） on the morphology of ZnO prepared by chemical bath ...The control of the morphology of zinc oxide（ZnO） crystals is very important in science and industry.This article reports the influence of bacterial cellulose（BC） on the morphology of ZnO prepared by chemical bath deposition.ZnO nanostructures synthesized with and without adding BC to the aqueous solution of zinc acetate and ammonia were characterized by scanning electron microscopy,transmission electron microscopy,and X-ray diffraction.The results reveal that the presence of BC in the aqueous solution changes the morphology from spindle to flower,which is ascribed to the interactions between –OH on BC nanofibers and Zn2？in the solution.In addition,optical property of the two ZnO nanostructures was compared.展开更多
文摘In this work, patterned macropores with a diameter larger than 100 μm were introduced to pristine three-dimensional (3D) nanofibrous bacterial cellulose (BC) scaffolds by using the infrared laser micromachining technique in an attempt to create an in vitro model for the culture of breast cancer cells. The morphology, pore structure, and mechanical performance of the obtained patterned macroporous BC (PM-BC) scaffolds were characterized by scanning electron microscopy (SEM), mercury intrusion porosimeter, and mechanical testing. A human breast cancer cell (MDA-MB-231) line was cultured onto the PM-BC scaffolds to investigate the role of macropores in the control of cancer cell behavior. MTT assay, SEM, and hematoxylin and eosin (H&E) staining were employed to determine cell adhesion, growth, proliferation, and infiltration. The PM-BC scaffolds were found to be able to promote cellular adhesion and proliferation on the scaffolds, and further to allow for cell infiltration into the PM-BC scaffolds. The results demonstrated that BC scaffolds with laser-patterned macropores were promising for the in vitro 3D culture of breast cancer cells.
基金This work was supported by the National Natural Science Foundation of China(Nos.51775503 and 51875343)the Natural Science Foundation of Zhejiang Province(No.LY17E050020)+1 种基金the China Postdoctoral ScienceFoundation(Nos.2017M620152and 2018T110392)Jiangxi Natural Science Foundation of China(20171BCD40009).
文摘Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3particleswithsizesintherange5to200 μmonapin-on-flattribo-testerunderdryreciprocatingsliding conditions at room temperature. Based on the examined worn surface characteristics of both PTFE and 316L stainless steel (as a counterpart) and the analyzed coefficient of friction (COF) evolutions, the wear mechanism and particle size effect have been explored in detail. The results demonstrate that the abrasive size is the main contributing factor, which can drastically impact the wear mechanism and tribological properties of tribo-pairs. The COF exhibits different evolution characteristics (trends) for different abrasive sizes. For moderate particle sizes, the COF trends become more complicated and the most evident wear of the metallic counterpart is evident. The activity behaviors of abrasives are dominated by the particle size. Particles can becomes embedded in one of the tribo-pair materials to plough-cut the counterpart, thus causing two-body abrasive wear. The abrasives can also behave as free rolling bodies, which play the role of third body to realize three-body "PTFE-abrasive-316L"abrasion. When abrasives are involved in the wear process, both the wear rate and COF of the metallic counterpart increase, but the material removal rate of the PTFE is reduced. The results obtained can offer guidelines regarding the design and protection of seals.
基金financially supported by the National Natural Science Foundation of China (Nos.51172158 and 81200663)the Science and Technology Support Program of Tianjin (No.11ZCKFSY01700)
文摘The control of the morphology of zinc oxide（ZnO） crystals is very important in science and industry.This article reports the influence of bacterial cellulose（BC） on the morphology of ZnO prepared by chemical bath deposition.ZnO nanostructures synthesized with and without adding BC to the aqueous solution of zinc acetate and ammonia were characterized by scanning electron microscopy,transmission electron microscopy,and X-ray diffraction.The results reveal that the presence of BC in the aqueous solution changes the morphology from spindle to flower,which is ascribed to the interactions between –OH on BC nanofibers and Zn2？in the solution.In addition,optical property of the two ZnO nanostructures was compared.
