We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to be...We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to better understand the behaviors of Zn and Sr as trace-elements in the caries eruption with respect to the behaviors of one of the main compounds of the hydroxyapatite crystal which is the calcium.The study was focused on the investigation of these elements’evolutions from three parts of the enamel surfaces of twenty two adult caries-affected teeth;the healthy part,the dental plaque part and the caries-affected part.The decrease rates of Zn,Sr and P was,also,compared to the Ca one.Comparison concerned normalized emission line intensities.For every species,normalization was done relatively to the emission line intensities of the healthy part.Results showed that abundances of these elements decrease similarly from the healthy parts to the affected-caries parts.The higher decrease rate was noticed for the calcium.The evolutions of Zn and Sr for the three parts of the teeth surfaces cannot inform about the substitution of the calcium by these trace-elements,however the comparison of their decrease rates to the calcium one can be considered as a valuable index of this substitution.展开更多
This work presented the characteristics of two gear teeth finishing methods, due to the properties of gear teeth surface layer obtained at the tooth working depth. These methods are: 1) the teeth carburization, harden...This work presented the characteristics of two gear teeth finishing methods, due to the properties of gear teeth surface layer obtained at the tooth working depth. These methods are: 1) the teeth carburization, hardening to a hardness of HRC 60-62 and then grinding, 2) the soft gear shaving as the final mechanical treatment and then carburizing and hardening to the hardness of HRC60-62. This work included the test results of the contact fatigue strength carried out on the circulating power system. The Wohler curves were plotted due to the obtained results, as the basis for the practical evaluation of the considered gear finishing methods. The parameters like volume distribution of the voids, content of the retained austenite, compressive residual stress value, but also the results of contact fatigue strength tests, are more favorable for the teeth shaving method than for the teeth grinding method.展开更多
文摘We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to better understand the behaviors of Zn and Sr as trace-elements in the caries eruption with respect to the behaviors of one of the main compounds of the hydroxyapatite crystal which is the calcium.The study was focused on the investigation of these elements’evolutions from three parts of the enamel surfaces of twenty two adult caries-affected teeth;the healthy part,the dental plaque part and the caries-affected part.The decrease rates of Zn,Sr and P was,also,compared to the Ca one.Comparison concerned normalized emission line intensities.For every species,normalization was done relatively to the emission line intensities of the healthy part.Results showed that abundances of these elements decrease similarly from the healthy parts to the affected-caries parts.The higher decrease rate was noticed for the calcium.The evolutions of Zn and Sr for the three parts of the teeth surfaces cannot inform about the substitution of the calcium by these trace-elements,however the comparison of their decrease rates to the calcium one can be considered as a valuable index of this substitution.
文摘This work presented the characteristics of two gear teeth finishing methods, due to the properties of gear teeth surface layer obtained at the tooth working depth. These methods are: 1) the teeth carburization, hardening to a hardness of HRC 60-62 and then grinding, 2) the soft gear shaving as the final mechanical treatment and then carburizing and hardening to the hardness of HRC60-62. This work included the test results of the contact fatigue strength carried out on the circulating power system. The Wohler curves were plotted due to the obtained results, as the basis for the practical evaluation of the considered gear finishing methods. The parameters like volume distribution of the voids, content of the retained austenite, compressive residual stress value, but also the results of contact fatigue strength tests, are more favorable for the teeth shaving method than for the teeth grinding method.
