The purpose of this study was to evaluate the antibacterial activity of a modified self-etching primer incorporating chitosan and whether this modification affected the bond strength to radicular dentin.A modified sel...The purpose of this study was to evaluate the antibacterial activity of a modified self-etching primer incorporating chitosan and whether this modification affected the bond strength to radicular dentin.A modified self-etching primer was prepared by adding chitosan solutions at 0.03%,0.06%,0.12% and 0.25%（W/W） to RealSeal selfetching primer.RealSeal primer without chitosan was used as the control.The antibacterial activity of the modified self-etching primer was evaluated using the direct contact test against Enterococcus faecalis.The bonding ability of the RealSeal system to radicular dentin was evaluated using the push-out bond strength test.The modes of failure were examined under a stereomicroscope.Data were analyzed using analysis of variance（ANOVA） and Tukey’s test,with a P-value 〈 0.05 indicating statistical significance.The results showed that the antibacterial properties of the freshly prepared and aged modified self-etching primer incorporating chitosan exhibited potent antibacterial effect against Enterococcus faecalis compared with the unmodified primer.The RealSeal system with the aged modified self-etching primer incorporating chitosan showed no significant differences in the bond strength as compared with the control（P = 0.99）.The findings suggest that modified self-etching primer incorporating chitosan is a promising antibacterial primer which does not adversely affect the bond strength of the RealSeal system to radicular dentin.展开更多
This study examined the adhesive strength of two self-adhesive methacrylate resin-based sealers（MetaSEAL and RealSeal SE） to root dentin and compared them with RealSeal and AH Plus in properties. A total of 48 extra...This study examined the adhesive strength of two self-adhesive methacrylate resin-based sealers（MetaSEAL and RealSeal SE） to root dentin and compared them with RealSeal and AH Plus in properties. A total of 48 extracted human single-rooted teeth were used to prepare the 0.9-mm thick longitudinal tooth slice（each per tooth）. Standardized simulated canal spaces of uniform dimensions were prepared in the middle of radicular dentin. After treated with 5.25% sodium hypochlorite（NaOCl） and 17% EDTA, tooth slices were allocated randomly to four groups（n=12） in terms of different sealers used： MetaSEAL, RealSeal SE, RealSeal, and AH plus groups. The simulated canal spaces were obturated with different sealers in each group. There were 10 slabs with 20 simulated canal spaces（n=20） used in each group for push-out testing. The failure modes and the ultrastructures of fractured sealer-dentin interfaces were examined. The remaining 2 slabs in each group underwent partial demineralization for observation of the ultrastructure of resin tags. The results showed that the push-out bond strength was 12.01±4.66 MPa in MetaSEAL group, significantly higher than that in the other three groups（P0.05）. Moreover, no statistically significant differences were noted in the push-out bond strength between RealSeal SE（5.43±3.68 MPa） and AH Plus（7.34±2.83 MPa） groups and between RealSeal SE and RealSeal（2.93±1.76 MPa） groups（P0.05）. Mixed failures were predominant in the fractured sealer-dentin interfaces in MetaSEAL and AH Plus groups, while adhesive failures were frequently seen in RealSeal SE and RealSeal groups. In conclusion, after complete removal of the smear layer, MetaSEAL showed superior bond ability to root dentin. The RealSeal SE is applicable in clinical practice, with its adhesive strength similar to that of AH Plus. The self-adhesive methacrylate resin-based sealer holds promise for use in endodontic treatment.展开更多
Based on the interphase layer model and the spring layer model, an improved interface model was developed to evaluate the interfacial shear strength of Titanium matrix composites(TMCs) and to analyze the effects of va...Based on the interphase layer model and the spring layer model, an improved interface model was developed to evaluate the interfacial shear strength of Titanium matrix composites(TMCs) and to analyze the effects of various parameters on the interfacial properties. The results showed that the improved interface model is more suitable for calculating the interfacial properties of SiC fiber reinforced titanium matrix composites. The interfacial shear strength of SiC/Timetal-834 predicted is 500 MPa. In addition, in order to better understand the interfacial properties of composites, some push out phenomenon were analyzed.展开更多
Aiming at the problems of low success rate and high seedling injury rate of automatic vegetable transplanting,this study focused on cabbage substrate block seedlings and developed a progressive push-out automatic seed...Aiming at the problems of low success rate and high seedling injury rate of automatic vegetable transplanting,this study focused on cabbage substrate block seedlings and developed a progressive push-out automatic seedling device controlled by a PLC system.Based on the friction mechanical properties of seedlings-tray during seedling taking,the collision rebound theoretical analysis of substrate block seedling delivery and the finite element simulation analysis of the seedling taking mechanism were carried out to determine the conditions for stable seedling taking and delivery of the device and the working parameters of the key mechanisms.To evaluate individual parameter effects,a test bench was built,and the effective ranges of key factors were subsequently determined.Three key experimental factors,the inclination angle of the limit guide plate,the seedling separation channel width,and the seedling separation cylinder pressure,were investigated using an L9(34)orthogonal array design with blockage rate and breakage rate as evaluation metrics.The range and variance analysis methods were employed to determine the relative significance of each factor’s influence on the performance indicators.The optimal parameters were determined as:the inclination angle of the limiting guide plate was 3.5°,the width of the seedling separation channel was 50 mm,and the pressure of the seedling separation cylinder was 0.6 MPa.Under these conditions,the seedling taking effect was significantly improved:the blockage rate was 2.46%,the breakage rate was 3.18%,and the seedling taking success rate was 94.36%.The optimal parameter combination was verified by the experiment:the average blockage rate was 3.23%,the average breakage rate was 3.68%,and the average success rate was 93.09%.Compared with the orthogonal experiment,the relative success rate error was 1.27%,indicating that the device has high stability.This study will provide a reference for the design of automatic vegetable transplanters.展开更多
This study investigates the bond performance at the interfacial region shared by Ultra-High Performance Concrete(UHPC)and steel tubes through push-out tests.This study examines how changes in steel fiber volumetric ra...This study investigates the bond performance at the interfacial region shared by Ultra-High Performance Concrete(UHPC)and steel tubes through push-out tests.This study examines how changes in steel fiber volumetric ratio and thickness of steel tube influence the bond strength characteristics.The results show that as the enhancement of the steel tube wall thickness,the ultimate bond strength at the interface improves significantly,whereas the initial bond strength exhibits only slight variations.The influence of steel fiber volumetric ratio presents a nonlinear trend,with initial bond strength decreasing at low fiber content and increasing significantly as fiber content rises.Additionally,finite element(FE)simulations were applied to replicate the experimental conditions,and the outcomes showed strong correlation with the experimental data,confirming the exactitude of the FE model in predicting the bond behavior at the UHPC-Steel interface.These findings provide valuable insights for optimizing the design of UHPC-Filled steel tubes in high-performance structure.展开更多
文摘The purpose of this study was to evaluate the antibacterial activity of a modified self-etching primer incorporating chitosan and whether this modification affected the bond strength to radicular dentin.A modified self-etching primer was prepared by adding chitosan solutions at 0.03%,0.06%,0.12% and 0.25%（W/W） to RealSeal selfetching primer.RealSeal primer without chitosan was used as the control.The antibacterial activity of the modified self-etching primer was evaluated using the direct contact test against Enterococcus faecalis.The bonding ability of the RealSeal system to radicular dentin was evaluated using the push-out bond strength test.The modes of failure were examined under a stereomicroscope.Data were analyzed using analysis of variance（ANOVA） and Tukey’s test,with a P-value 〈 0.05 indicating statistical significance.The results showed that the antibacterial properties of the freshly prepared and aged modified self-etching primer incorporating chitosan exhibited potent antibacterial effect against Enterococcus faecalis compared with the unmodified primer.The RealSeal system with the aged modified self-etching primer incorporating chitosan showed no significant differences in the bond strength as compared with the control（P = 0.99）.The findings suggest that modified self-etching primer incorporating chitosan is a promising antibacterial primer which does not adversely affect the bond strength of the RealSeal system to radicular dentin.
文摘This study examined the adhesive strength of two self-adhesive methacrylate resin-based sealers（MetaSEAL and RealSeal SE） to root dentin and compared them with RealSeal and AH Plus in properties. A total of 48 extracted human single-rooted teeth were used to prepare the 0.9-mm thick longitudinal tooth slice（each per tooth）. Standardized simulated canal spaces of uniform dimensions were prepared in the middle of radicular dentin. After treated with 5.25% sodium hypochlorite（NaOCl） and 17% EDTA, tooth slices were allocated randomly to four groups（n=12） in terms of different sealers used： MetaSEAL, RealSeal SE, RealSeal, and AH plus groups. The simulated canal spaces were obturated with different sealers in each group. There were 10 slabs with 20 simulated canal spaces（n=20） used in each group for push-out testing. The failure modes and the ultrastructures of fractured sealer-dentin interfaces were examined. The remaining 2 slabs in each group underwent partial demineralization for observation of the ultrastructure of resin tags. The results showed that the push-out bond strength was 12.01±4.66 MPa in MetaSEAL group, significantly higher than that in the other three groups（P0.05）. Moreover, no statistically significant differences were noted in the push-out bond strength between RealSeal SE（5.43±3.68 MPa） and AH Plus（7.34±2.83 MPa） groups and between RealSeal SE and RealSeal（2.93±1.76 MPa） groups（P0.05）. Mixed failures were predominant in the fractured sealer-dentin interfaces in MetaSEAL and AH Plus groups, while adhesive failures were frequently seen in RealSeal SE and RealSeal groups. In conclusion, after complete removal of the smear layer, MetaSEAL showed superior bond ability to root dentin. The RealSeal SE is applicable in clinical practice, with its adhesive strength similar to that of AH Plus. The self-adhesive methacrylate resin-based sealer holds promise for use in endodontic treatment.
基金Supported by the Natural Science Foundation of Chinathe Aviation Science Foundation of Chinathe Doctoral Innovation Foundation of Northwestern Polytechnical University
文摘Based on the interphase layer model and the spring layer model, an improved interface model was developed to evaluate the interfacial shear strength of Titanium matrix composites(TMCs) and to analyze the effects of various parameters on the interfacial properties. The results showed that the improved interface model is more suitable for calculating the interfacial properties of SiC fiber reinforced titanium matrix composites. The interfacial shear strength of SiC/Timetal-834 predicted is 500 MPa. In addition, in order to better understand the interfacial properties of composites, some push out phenomenon were analyzed.
基金supported by the Fundamental Research Fund of the Chinese Academy of Agricultural Sciences at the Institute Level(Grant No.S202409)Jiangsu Modern Agricultural Machinery Equipment and Technology Demonstration and Promotion Project(Grant No.NJ2023-11)+2 种基金National Key R&D Program of China(Grant No.2023YFD2300700)Key Laboratory of Agricultural Equipment for Hilly and Mountainous Areas in Southeastern China(Co-construction by Ministry and Province)Ministry of Agriculture and Rural Affairs(Grant No.QSKF2023006).
文摘Aiming at the problems of low success rate and high seedling injury rate of automatic vegetable transplanting,this study focused on cabbage substrate block seedlings and developed a progressive push-out automatic seedling device controlled by a PLC system.Based on the friction mechanical properties of seedlings-tray during seedling taking,the collision rebound theoretical analysis of substrate block seedling delivery and the finite element simulation analysis of the seedling taking mechanism were carried out to determine the conditions for stable seedling taking and delivery of the device and the working parameters of the key mechanisms.To evaluate individual parameter effects,a test bench was built,and the effective ranges of key factors were subsequently determined.Three key experimental factors,the inclination angle of the limit guide plate,the seedling separation channel width,and the seedling separation cylinder pressure,were investigated using an L9(34)orthogonal array design with blockage rate and breakage rate as evaluation metrics.The range and variance analysis methods were employed to determine the relative significance of each factor’s influence on the performance indicators.The optimal parameters were determined as:the inclination angle of the limiting guide plate was 3.5°,the width of the seedling separation channel was 50 mm,and the pressure of the seedling separation cylinder was 0.6 MPa.Under these conditions,the seedling taking effect was significantly improved:the blockage rate was 2.46%,the breakage rate was 3.18%,and the seedling taking success rate was 94.36%.The optimal parameter combination was verified by the experiment:the average blockage rate was 3.23%,the average breakage rate was 3.68%,and the average success rate was 93.09%.Compared with the orthogonal experiment,the relative success rate error was 1.27%,indicating that the device has high stability.This study will provide a reference for the design of automatic vegetable transplanters.
基金supported by grants from the Natural Science Foundation of Fujian Province(2021J011062)Minjiang Scholars Funding(GY-633Z21067).
文摘This study investigates the bond performance at the interfacial region shared by Ultra-High Performance Concrete(UHPC)and steel tubes through push-out tests.This study examines how changes in steel fiber volumetric ratio and thickness of steel tube influence the bond strength characteristics.The results show that as the enhancement of the steel tube wall thickness,the ultimate bond strength at the interface improves significantly,whereas the initial bond strength exhibits only slight variations.The influence of steel fiber volumetric ratio presents a nonlinear trend,with initial bond strength decreasing at low fiber content and increasing significantly as fiber content rises.Additionally,finite element(FE)simulations were applied to replicate the experimental conditions,and the outcomes showed strong correlation with the experimental data,confirming the exactitude of the FE model in predicting the bond behavior at the UHPC-Steel interface.These findings provide valuable insights for optimizing the design of UHPC-Filled steel tubes in high-performance structure.
