The aim of this work is to analyze the stress distributions on a crown-luting cement-substrate system with a finite-element method in order to predict the likelihood of interfacial micro cracks, radial or circumferent...The aim of this work is to analyze the stress distributions on a crown-luting cement-substrate system with a finite-element method in order to predict the likelihood of interfacial micro cracks, radial or circumferential cracks, delamination, fracture and delamination with torsion. The contact and layer interface stresses in elastic layered half-space indented by an elastic sphere were examined using finite element method. The model consists of crown, luting cement and substrate. The solutions were carried out for three different elastic moduli of luting cement. It was placed between the cement and the substrate as a middle layer and its elastic module was chosen lower than the elastic module of crown and higher than the elastic module of dentin. An axisymmetric finite element mesh was set up for the stress analysis. Stress distributions on the contact surface and the interfaces of crown-luting cement and luting cement-dentin have been investigated for three different values of luting cement by using ANSYS. The effects of the luting cement which has three different elastic moduli on the pressure distribution and the location of interfacial stresses of the multi-layer model have been examined. The mechanism of crack initiation in the interfaces and interracial delamination was also studied quantitatively. For each luting cement, the pressure distribution is similar at the contact zone. Stress discontinuities occur at the perfect bonding interfaces of the crown-luting cement and the substrate-luting cement. The maximum stress jumps are obtained for the highest and the lowest elastic module of the luting cement. In the crown-luting cement-substrate system, failures may initiate at crown-luting cement region for luting cement with the lowest elastic module value. In addition, failures at luting cement-substrate region may occur for luting cement with the highest elastic module. In the luting cement, the medium elastic module value is more suitable for stress distribution in crown-luting cement-substrate interfaces.展开更多
We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars...We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin （1 mm below the dentine-enamel junction）, deep dentin （1 mm above the highest pulp horn） and cervical dentin （0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction）. Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm2 in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mrn/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin （P 〈 0.001）. Micro-ten- sile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions （P 〈 0.001）. Immediate ＂micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements （P 〈 0.001）. It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.展开更多
The purpose of this study was to investigate the influence of different luting agents on the stress distribution within the crown, abutment and peri-implant bone of implant-supported all-ceramic single crown. A three-...The purpose of this study was to investigate the influence of different luting agents on the stress distribution within the crown, abutment and peri-implant bone of implant-supported all-ceramic single crown. A three-dimensional finite element model of an implant-supported single crown for the first premolar of mandible was created by COSMOS 2.85. Resin-modified glass ionomer and two different resin adhesives were used to cement the crown and abutment. Vertical 600 N and horizontal 225 N loads were applied to stimulate the condition of chewing. The stress distributions within the all-ceramic crown, abutment and peri-implant bone were analyzed. The experimental results show that the stress distributions of all-ceramic crown, abutment, implant and peri-implant bone were similar when different luting agents were used. The result of present study indicated that luting agents had no influence on the stress distributions of implant-supported all-ceramic single crown.展开更多
Ionic liquid （1-ethyl-3-methylimidazolium tetrafluoroborate, 1E-3MI-TFB） and HP-β- CD as modifier was added to the buffer to separate hyperoside, luteolin and chlorogenic acid. Experiments explored the effect of co...Ionic liquid （1-ethyl-3-methylimidazolium tetrafluoroborate, 1E-3MI-TFB） and HP-β- CD as modifier was added to the buffer to separate hyperoside, luteolin and chlorogenic acid. Experiments explored the effect of concentration of 1E-3MI-TFB and HP-β-CD on separation. The results indicated that 1.0 mmol/L HP-β-CD and 1%0 （v/v） 1E-3MI-TFB added to the buffer simultaneously could achieve a good compromise of resolution and analysis time. Capillary experiments and UV spectra indicated that there was interaction between 1E-3MI-TFB and analytes.展开更多
荷兰汉学家高罗佩(Robert Hans Van Gulik)的The Lore of the Chinese Lute(《琴道》)一书,是对部分古琴相关古代文献进行翻译并整理分析的成果。本文尝试从比彻(Lloyd F. Bitzer)的“修辞形势”(The Rhetorical Situation)理论入手,解...荷兰汉学家高罗佩(Robert Hans Van Gulik)的The Lore of the Chinese Lute(《琴道》)一书,是对部分古琴相关古代文献进行翻译并整理分析的成果。本文尝试从比彻(Lloyd F. Bitzer)的“修辞形势”(The Rhetorical Situation)理论入手,解读译者是如何克服修辞局限,做到顺应并扭转修辞形势,从而达到传播中国古代琴学思想的翻译目的。展开更多
目的:探讨不同树脂水门汀对氧化锆陶瓷修复体粘接强度的影响。方法:制备牙本质粘接面样本30个随机分为3组(n=10),并选择Cercon氧化锆陶瓷系统分别与3种树脂水门汀进行配伍,制备相应剪切强度试件和拉伸强度试件,分别记为RU组(Cercon氧化...目的:探讨不同树脂水门汀对氧化锆陶瓷修复体粘接强度的影响。方法:制备牙本质粘接面样本30个随机分为3组(n=10),并选择Cercon氧化锆陶瓷系统分别与3种树脂水门汀进行配伍,制备相应剪切强度试件和拉伸强度试件,分别记为RU组(Cercon氧化锆与RelyX U200)、CS组(Cercon氧化锆与Clearfil SA Luting)、ME组(Cercon氧化锆与Maxcem Elite Chroma)。采用万能力学试验机检测各试件的最大剪切载荷值及最大拉伸载荷值,计算剪切强度及拉伸强度并进行统计学分析。结果:在剪切强度测试实验中,剪切强度CS组>RU组>ME组;在拉伸强度测试中,拉伸强度CS组>RU组>ME组;CS粘接剂在剪切强度和拉伸强度测试中粘接效果均优于RU和ME组。结论:在氧化锆陶瓷的剪切强度测试及拉伸强度测试中,含有10-MDP的树脂水门汀(Clearfil SA Luting)的粘接强度最大,粘接效果最好,对于氧化锆陶瓷推荐使用含MDP的树脂水门汀。展开更多
In the Yuan Dynasty,common people referred to those living at the lower strata of society,including the proletariat or small producers.Yuan Dynasty dramas depicted numerous images of common people.This paper begins wi...In the Yuan Dynasty,common people referred to those living at the lower strata of society,including the proletariat or small producers.Yuan Dynasty dramas depicted numerous images of common people.This paper begins with the image of“common people”and takes the Yuan Dynasty southern drama The Lute as its text.It deeply analyzes the fate trajectory of Cai Bojie and Zhao Wuniang,who represent common people in feudal society,exploring the reasons behind such tragic fates.Furthermore,it excavates the enduring literary value and contemporary significance of The Lute.The Lute not only reflects society and the era from a literary and artistic perspective but also perceives the tragic fate of common people during the feudal period.Indirectly,it demonstrates the significant contribution of traditional Chinese opera to the reconstruction of cultural concepts and moral-ethical notions.展开更多
文摘The aim of this work is to analyze the stress distributions on a crown-luting cement-substrate system with a finite-element method in order to predict the likelihood of interfacial micro cracks, radial or circumferential cracks, delamination, fracture and delamination with torsion. The contact and layer interface stresses in elastic layered half-space indented by an elastic sphere were examined using finite element method. The model consists of crown, luting cement and substrate. The solutions were carried out for three different elastic moduli of luting cement. It was placed between the cement and the substrate as a middle layer and its elastic module was chosen lower than the elastic module of crown and higher than the elastic module of dentin. An axisymmetric finite element mesh was set up for the stress analysis. Stress distributions on the contact surface and the interfaces of crown-luting cement and luting cement-dentin have been investigated for three different values of luting cement by using ANSYS. The effects of the luting cement which has three different elastic moduli on the pressure distribution and the location of interfacial stresses of the multi-layer model have been examined. The mechanism of crack initiation in the interfaces and interracial delamination was also studied quantitatively. For each luting cement, the pressure distribution is similar at the contact zone. Stress discontinuities occur at the perfect bonding interfaces of the crown-luting cement and the substrate-luting cement. The maximum stress jumps are obtained for the highest and the lowest elastic module of the luting cement. In the crown-luting cement-substrate system, failures may initiate at crown-luting cement region for luting cement with the lowest elastic module value. In addition, failures at luting cement-substrate region may occur for luting cement with the highest elastic module. In the luting cement, the medium elastic module value is more suitable for stress distribution in crown-luting cement-substrate interfaces.
文摘We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin （1 mm below the dentine-enamel junction）, deep dentin （1 mm above the highest pulp horn） and cervical dentin （0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction）. Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm2 in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mrn/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin （P 〈 0.001）. Micro-ten- sile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions （P 〈 0.001）. Immediate ＂micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements （P 〈 0.001）. It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.
基金Funded by the National Natural Science Foundation of China(No.81100784)
文摘The purpose of this study was to investigate the influence of different luting agents on the stress distribution within the crown, abutment and peri-implant bone of implant-supported all-ceramic single crown. A three-dimensional finite element model of an implant-supported single crown for the first premolar of mandible was created by COSMOS 2.85. Resin-modified glass ionomer and two different resin adhesives were used to cement the crown and abutment. Vertical 600 N and horizontal 225 N loads were applied to stimulate the condition of chewing. The stress distributions within the all-ceramic crown, abutment and peri-implant bone were analyzed. The experimental results show that the stress distributions of all-ceramic crown, abutment, implant and peri-implant bone were similar when different luting agents were used. The result of present study indicated that luting agents had no influence on the stress distributions of implant-supported all-ceramic single crown.
基金the National Natural Science Foundation of China （No. 20175025, 29875027, 20235010）.
文摘Ionic liquid （1-ethyl-3-methylimidazolium tetrafluoroborate, 1E-3MI-TFB） and HP-β- CD as modifier was added to the buffer to separate hyperoside, luteolin and chlorogenic acid. Experiments explored the effect of concentration of 1E-3MI-TFB and HP-β-CD on separation. The results indicated that 1.0 mmol/L HP-β-CD and 1%0 （v/v） 1E-3MI-TFB added to the buffer simultaneously could achieve a good compromise of resolution and analysis time. Capillary experiments and UV spectra indicated that there was interaction between 1E-3MI-TFB and analytes.
文摘荷兰汉学家高罗佩(Robert Hans Van Gulik)的The Lore of the Chinese Lute(《琴道》)一书,是对部分古琴相关古代文献进行翻译并整理分析的成果。本文尝试从比彻(Lloyd F. Bitzer)的“修辞形势”(The Rhetorical Situation)理论入手,解读译者是如何克服修辞局限,做到顺应并扭转修辞形势,从而达到传播中国古代琴学思想的翻译目的。
文摘目的:探讨不同树脂水门汀对氧化锆陶瓷修复体粘接强度的影响。方法:制备牙本质粘接面样本30个随机分为3组(n=10),并选择Cercon氧化锆陶瓷系统分别与3种树脂水门汀进行配伍,制备相应剪切强度试件和拉伸强度试件,分别记为RU组(Cercon氧化锆与RelyX U200)、CS组(Cercon氧化锆与Clearfil SA Luting)、ME组(Cercon氧化锆与Maxcem Elite Chroma)。采用万能力学试验机检测各试件的最大剪切载荷值及最大拉伸载荷值,计算剪切强度及拉伸强度并进行统计学分析。结果:在剪切强度测试实验中,剪切强度CS组>RU组>ME组;在拉伸强度测试中,拉伸强度CS组>RU组>ME组;CS粘接剂在剪切强度和拉伸强度测试中粘接效果均优于RU和ME组。结论:在氧化锆陶瓷的剪切强度测试及拉伸强度测试中,含有10-MDP的树脂水门汀(Clearfil SA Luting)的粘接强度最大,粘接效果最好,对于氧化锆陶瓷推荐使用含MDP的树脂水门汀。
文摘In the Yuan Dynasty,common people referred to those living at the lower strata of society,including the proletariat or small producers.Yuan Dynasty dramas depicted numerous images of common people.This paper begins with the image of“common people”and takes the Yuan Dynasty southern drama The Lute as its text.It deeply analyzes the fate trajectory of Cai Bojie and Zhao Wuniang,who represent common people in feudal society,exploring the reasons behind such tragic fates.Furthermore,it excavates the enduring literary value and contemporary significance of The Lute.The Lute not only reflects society and the era from a literary and artistic perspective but also perceives the tragic fate of common people during the feudal period.Indirectly,it demonstrates the significant contribution of traditional Chinese opera to the reconstruction of cultural concepts and moral-ethical notions.
