The purpose of this study was to evaluate the long time antibacterial properties and shear bond strength of experimental nano silver-containing cements （NSC）. Nano silver base inorganic antibacterial powder was adde...The purpose of this study was to evaluate the long time antibacterial properties and shear bond strength of experimental nano silver-containing cements （NSC）. Nano silver base inorganic antibacterial powder was added to the reinforced glass ionomer cement at five different weight ratios to obtain a series of nano silver-containing cements, then the antibacterial properties of three orthodontic cement products and five NSC samples were evaluated by the direct contact test （DCT） and the agar diffusion test （ADT）. The DCT, which was based on turbidness determination of bacterial growth in 96-well microtiter plates, was performed in both fresh and aged for 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, and 8 weeks tested materials. The shear bond strengthes of three orthodontic cement products and five NSC samples were examined using a universal testing machine. The ADT results indicated that there were no significant differences between NSCs and ORTHO LC fresh specimens. In the DCT experiment, all fresh silver nanoparticles-containing tested samples presented powerful antibacterial properties, but they gradually lost the effective antimicrobial agents with the extension of aging time. Finally, none of the tested materials maintained its antibacterial property after aging for 8 weeks. A gradually decreasing trend of bond strength presented with the increasing incorporation of nano silver base inorganic antibacterial powder into the glass ionomer cement, even though all the tested material specimens reached the ideal bond strength range. We may conclude that NSCs can contribute to decrease the demineralization rate around brackets without compromising bond strength.展开更多
目的:探究观察3M Single Bond Universal粘接系统对前牙E-max铸瓷贴面修复的远期疗效。方法:选择2017年5月-2019年5月笔者医院收治的需前牙E-max铸瓷贴面修复患者63例(患牙113颗)为研究对象,均行经典贴面修复,根据粘接系统的不同将患者...目的:探究观察3M Single Bond Universal粘接系统对前牙E-max铸瓷贴面修复的远期疗效。方法:选择2017年5月-2019年5月笔者医院收治的需前牙E-max铸瓷贴面修复患者63例(患牙113颗)为研究对象,均行经典贴面修复,根据粘接系统的不同将患者分为观察组(患者21例,患牙40颗,采用3M Single Bond Universal粘接系统)、对照1组(患者21例,患牙36颗,采用VariolinkⅡ粘接系统)、对照2组(患者21例,患牙37颗,采用BISCO CHOICE 2粘接系统)。治疗后三组均于1周、3个月、12个月时进行随访,观察三组治疗后1周、3个月、12个月内贴面修复效果、贴面修复失败率及不良反应发生率。结果:术后1周,三组患者均无失败案例;对照1组存在2颗修复体保存完整度为Ⅰ级的患牙,对照2组存在3颗修复体保存完整度为I级的患牙,观察组未存在该类患者;术后12个月,观察组存在1颗修复体保存完整度Ⅱ级患牙,对照1组存在1颗保存完整度I级患牙,3颗修复体保存完整度Ⅱ级患牙,对照2组存在2颗保存完整度I级患牙,3颗修复体保存完整度Ⅱ级患牙。三组患者治疗效果比较,差异无统计学意义(P>0.05);术后1周、3个月、12个月三组贴面修复失败率比较,差异无统计学意义(P>0.05);随访期间内,三组患者不良反应情况比较差异均无统计学意义(P>0.05)。结论:对于前牙E-max铸瓷贴面修复患者,选取合适的适应证,并做好备牙步骤,3M Single Bond Universal与经典VariolinkⅡ粘接系统及BISCO CHOICE 2粘接系统治疗效果并无显著差异,值得在临床推广使用。展开更多
In this paper a generalized defaultable bond pricing formula is derived by assuming that there exists a defaultable forward rate term structure and that firms in the economy interact when default occurs.Generally,The ...In this paper a generalized defaultable bond pricing formula is derived by assuming that there exists a defaultable forward rate term structure and that firms in the economy interact when default occurs.Generally,The risk-neutral default intensity λ Q is not equal to the empirical or actual default intensity λ.This paper proves that multiple default intensities are invariant under equivalent martingale transformation,given a well-diversified portfolio corresponding to the defaultable bond.Thus one can directly apply default intensities and fractional losses empirically estimated to the evaluation of defaultable bonds or contingent claims.展开更多
Nelson-Siegel model （ NS model） and 2 extended NS models were compared by using daily interbank government bond data Based on the grouping of bonds according to the residual term to maturity, the empirical research ...Nelson-Siegel model （ NS model） and 2 extended NS models were compared by using daily interbank government bond data Based on the grouping of bonds according to the residual term to maturity, the empirical research proceeded with in-sample and outof-sample tests. The results show that the 3 models are almost equivalent in estimating interbank term structure of interest rates. Within the term to maturities between 0 and 7 years, the gap of the absolute errors of the 3 models between in-sample and out-of-sample is smRller than 0.2 Yuan, and the absolute values of the in-sample and out-of-sample errors are smaller than 0. 1 Yuan, so the estimation is credible. Within the term to maturities between 7 and 20 years, the gap of the absolute errors of the 3 models between in-sample and out-of-sample is larger than 0.4 Yuan, and the absolute values of the in-sample and out-of-sample errors are larger than 1.0 Yuan, so the estimation is incredible.展开更多
基金Funded by the Natural Science Foundation of Hubei Province(No.2012FFB04416)
文摘The purpose of this study was to evaluate the long time antibacterial properties and shear bond strength of experimental nano silver-containing cements （NSC）. Nano silver base inorganic antibacterial powder was added to the reinforced glass ionomer cement at five different weight ratios to obtain a series of nano silver-containing cements, then the antibacterial properties of three orthodontic cement products and five NSC samples were evaluated by the direct contact test （DCT） and the agar diffusion test （ADT）. The DCT, which was based on turbidness determination of bacterial growth in 96-well microtiter plates, was performed in both fresh and aged for 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, and 8 weeks tested materials. The shear bond strengthes of three orthodontic cement products and five NSC samples were examined using a universal testing machine. The ADT results indicated that there were no significant differences between NSCs and ORTHO LC fresh specimens. In the DCT experiment, all fresh silver nanoparticles-containing tested samples presented powerful antibacterial properties, but they gradually lost the effective antimicrobial agents with the extension of aging time. Finally, none of the tested materials maintained its antibacterial property after aging for 8 weeks. A gradually decreasing trend of bond strength presented with the increasing incorporation of nano silver base inorganic antibacterial powder into the glass ionomer cement, even though all the tested material specimens reached the ideal bond strength range. We may conclude that NSCs can contribute to decrease the demineralization rate around brackets without compromising bond strength.
文摘目的:探究观察3M Single Bond Universal粘接系统对前牙E-max铸瓷贴面修复的远期疗效。方法:选择2017年5月-2019年5月笔者医院收治的需前牙E-max铸瓷贴面修复患者63例(患牙113颗)为研究对象,均行经典贴面修复,根据粘接系统的不同将患者分为观察组(患者21例,患牙40颗,采用3M Single Bond Universal粘接系统)、对照1组(患者21例,患牙36颗,采用VariolinkⅡ粘接系统)、对照2组(患者21例,患牙37颗,采用BISCO CHOICE 2粘接系统)。治疗后三组均于1周、3个月、12个月时进行随访,观察三组治疗后1周、3个月、12个月内贴面修复效果、贴面修复失败率及不良反应发生率。结果:术后1周,三组患者均无失败案例;对照1组存在2颗修复体保存完整度为Ⅰ级的患牙,对照2组存在3颗修复体保存完整度为I级的患牙,观察组未存在该类患者;术后12个月,观察组存在1颗修复体保存完整度Ⅱ级患牙,对照1组存在1颗保存完整度I级患牙,3颗修复体保存完整度Ⅱ级患牙,对照2组存在2颗保存完整度I级患牙,3颗修复体保存完整度Ⅱ级患牙。三组患者治疗效果比较,差异无统计学意义(P>0.05);术后1周、3个月、12个月三组贴面修复失败率比较,差异无统计学意义(P>0.05);随访期间内,三组患者不良反应情况比较差异均无统计学意义(P>0.05)。结论:对于前牙E-max铸瓷贴面修复患者,选取合适的适应证,并做好备牙步骤,3M Single Bond Universal与经典VariolinkⅡ粘接系统及BISCO CHOICE 2粘接系统治疗效果并无显著差异,值得在临床推广使用。
基金National Natural Science Foundation of China(70 0 71 0 1 2 )
文摘In this paper a generalized defaultable bond pricing formula is derived by assuming that there exists a defaultable forward rate term structure and that firms in the economy interact when default occurs.Generally,The risk-neutral default intensity λ Q is not equal to the empirical or actual default intensity λ.This paper proves that multiple default intensities are invariant under equivalent martingale transformation,given a well-diversified portfolio corresponding to the defaultable bond.Thus one can directly apply default intensities and fractional losses empirically estimated to the evaluation of defaultable bonds or contingent claims.
文摘Nelson-Siegel model （ NS model） and 2 extended NS models were compared by using daily interbank government bond data Based on the grouping of bonds according to the residual term to maturity, the empirical research proceeded with in-sample and outof-sample tests. The results show that the 3 models are almost equivalent in estimating interbank term structure of interest rates. Within the term to maturities between 0 and 7 years, the gap of the absolute errors of the 3 models between in-sample and out-of-sample is smRller than 0.2 Yuan, and the absolute values of the in-sample and out-of-sample errors are smaller than 0. 1 Yuan, so the estimation is credible. Within the term to maturities between 7 and 20 years, the gap of the absolute errors of the 3 models between in-sample and out-of-sample is larger than 0.4 Yuan, and the absolute values of the in-sample and out-of-sample errors are larger than 1.0 Yuan, so the estimation is incredible.
