Background- The use of sirolimus- eluting coronary stents has been associated with a nearly complete elimination of restenosis at 6 months and with a very low 1- year incidence of major adverse cardiac events(MACE). T...Background- The use of sirolimus- eluting coronary stents has been associated with a nearly complete elimination of restenosis at 6 months and with a very low 1- year incidence of major adverse cardiac events(MACE). This analysis examined whether these beneficial effects persist over the longer term. Methods and Results- This multicenter trial randomly assigned 238 patients to revascularization of single, de novo, native coronary artery lesions with sirolimus- eluting versus conventional baremetal stents. Survival free from target lesion revascularization(TLR), target vessel failure(TVF), and MACE up to 3 years of follow- up was compared between the 2 treatment groups. Complete data sets were available in 94.2% of patients treated with sirolimus- eluting stents and in 94.1% of patients randomized to the control group. The cumulative 1- , 2- , and 3- year event- free survival rates were 99.2% , 96.5% , and 93.7% for TLR and 95.8% , 92.3% , and 87.9% for TVF, respectively, in the sirolimus- eluting stent group, versus 75.9% , 75.9% , and 75.0% for TLR and 71.2% , 69.4% , and 67.3% for TVF in the control group(P< 0.001 for both comparisons at 3 years). Rates of MACE at 3 years were 15.8% in patients randomly assigned to sirolimus- eluting stents versus 33.1% in patients assigned to bare- metal stents(P=0.002). One patient treated with a sirolimus- eluting stent died of a cardiac cause between 12 and 36 months. Conclusions- Treatment of de novo coronary stenosis with sirolimus- eluting stents was associated with a sustained clinical benefit and very low rates of TLR and of other MACE up to 3 years after device implantation.展开更多
Raveling is a common distress of asphalt pavements,defined as the removal of stones from the pavement surface.To predict and assess raveling quantitatively,a cumulative damage model based on an energy dissipation appr...Raveling is a common distress of asphalt pavements,defined as the removal of stones from the pavement surface.To predict and assess raveling quantitatively,a cumulative damage model based on an energy dissipation approach has been developed at the meso level.To construct the model,a new test method,the pendulum impact test,was employed to determine the fracture energy of the stone-mastic-stone meso-unit,while digital image analysis and dynamic shear rheometer test were used to acquire the strain rate of specimens and the rheology property of mastic,respectively.Analysis of the model reveals that when the material properties remain constant,the cumulative damage is directly correlated with loading time,loading amplitude,and loading frequency.Specifically,damage increases with superimposed linear and cosine variations over time.A higher stress amplitude results in a more rapidly increasing rate of damage,while a lower load frequency leads to more severe damage within the same loading time.Moreover,an example of the application of the model has been presented,showing that the model can be utilized to estimate failure life due to raveling.The model is able to offer a theoretical foundation for the design and maintenance of anti-raveling asphalt pavements.展开更多
Full-Depth Reclamation （FDR） is a sustainable method of building pavement structure compared to more traditional rehabilitation methods. Traffic is generally returned to an FDR project before a surface course is app...Full-Depth Reclamation （FDR） is a sustainable method of building pavement structure compared to more traditional rehabilitation methods. Traffic is generally returned to an FDR project before a surface course is applied, as water in the FDR needs time to evaporate from the structure. This should not be done too quickly or raveling occurs. Currently, there is no test to quantify the timing of return to traffic. In this study, the ＂Raveling test of cold mixed bituminous emulsion samples＂ （ASTM D7196） was used to compare asphalt emulsion and asphalt foam FDR. Asphalt emulsion samples were cured at ambient and 40℃ temperatures, while asphalt foam samples were cured at ambient temperatures. Raveling test data was collected from 0 to 48 hours of curing, however, samples were often not able to withstand fifteen minutes of testing. Therefore, the ＂time lasted＂ （the time the raveling head loses contact with the surface of the sample） was recorded. In general, the asphalt emulsion samples that were cured in the oven at 40℃ had a longer time lasted and showed higher potential for determination of return to traffic. In addition, the asphalt emulsion samples had a longer time lasted than the asphalt foam samples at ambient temperatures.展开更多
文摘Background- The use of sirolimus- eluting coronary stents has been associated with a nearly complete elimination of restenosis at 6 months and with a very low 1- year incidence of major adverse cardiac events(MACE). This analysis examined whether these beneficial effects persist over the longer term. Methods and Results- This multicenter trial randomly assigned 238 patients to revascularization of single, de novo, native coronary artery lesions with sirolimus- eluting versus conventional baremetal stents. Survival free from target lesion revascularization(TLR), target vessel failure(TVF), and MACE up to 3 years of follow- up was compared between the 2 treatment groups. Complete data sets were available in 94.2% of patients treated with sirolimus- eluting stents and in 94.1% of patients randomized to the control group. The cumulative 1- , 2- , and 3- year event- free survival rates were 99.2% , 96.5% , and 93.7% for TLR and 95.8% , 92.3% , and 87.9% for TVF, respectively, in the sirolimus- eluting stent group, versus 75.9% , 75.9% , and 75.0% for TLR and 71.2% , 69.4% , and 67.3% for TVF in the control group(P< 0.001 for both comparisons at 3 years). Rates of MACE at 3 years were 15.8% in patients randomly assigned to sirolimus- eluting stents versus 33.1% in patients assigned to bare- metal stents(P=0.002). One patient treated with a sirolimus- eluting stent died of a cardiac cause between 12 and 36 months. Conclusions- Treatment of de novo coronary stenosis with sirolimus- eluting stents was associated with a sustained clinical benefit and very low rates of TLR and of other MACE up to 3 years after device implantation.
基金The authors gratefully acknowledge the financial supports by the National Natural Science Foundation of China(Grant No.51278203)the Natural Science Fund of Guangdong Province(No.2019A1515011965).
文摘Raveling is a common distress of asphalt pavements,defined as the removal of stones from the pavement surface.To predict and assess raveling quantitatively,a cumulative damage model based on an energy dissipation approach has been developed at the meso level.To construct the model,a new test method,the pendulum impact test,was employed to determine the fracture energy of the stone-mastic-stone meso-unit,while digital image analysis and dynamic shear rheometer test were used to acquire the strain rate of specimens and the rheology property of mastic,respectively.Analysis of the model reveals that when the material properties remain constant,the cumulative damage is directly correlated with loading time,loading amplitude,and loading frequency.Specifically,damage increases with superimposed linear and cosine variations over time.A higher stress amplitude results in a more rapidly increasing rate of damage,while a lower load frequency leads to more severe damage within the same loading time.Moreover,an example of the application of the model has been presented,showing that the model can be utilized to estimate failure life due to raveling.The model is able to offer a theoretical foundation for the design and maintenance of anti-raveling asphalt pavements.
文摘Full-Depth Reclamation （FDR） is a sustainable method of building pavement structure compared to more traditional rehabilitation methods. Traffic is generally returned to an FDR project before a surface course is applied, as water in the FDR needs time to evaporate from the structure. This should not be done too quickly or raveling occurs. Currently, there is no test to quantify the timing of return to traffic. In this study, the ＂Raveling test of cold mixed bituminous emulsion samples＂ （ASTM D7196） was used to compare asphalt emulsion and asphalt foam FDR. Asphalt emulsion samples were cured at ambient and 40℃ temperatures, while asphalt foam samples were cured at ambient temperatures. Raveling test data was collected from 0 to 48 hours of curing, however, samples were often not able to withstand fifteen minutes of testing. Therefore, the ＂time lasted＂ （the time the raveling head loses contact with the surface of the sample） was recorded. In general, the asphalt emulsion samples that were cured in the oven at 40℃ had a longer time lasted and showed higher potential for determination of return to traffic. In addition, the asphalt emulsion samples had a longer time lasted than the asphalt foam samples at ambient temperatures.
