(K0.47Na0.47Li0.06)NbO3 (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k2CO3-Na2CO3 eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at ...(K0.47Na0.47Li0.06)NbO3 (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k2CO3-Na2CO3 eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at 980-1 030 ℃ were investigated. The calcined powders were examined by X-ray diffraction. The microstructure of the calcined powders and sintered bodies was observed using a scanning electron microscope (SEM).The piezoelectric constant d33 was measured using a quasi-static piezoelectric d33 meter. The planar coupling coefficient Kp was calculated by resonance-antiresonance method. The experimental data for each sample's performance indicators were the average values of 8 specimens. The relative densities of sintered specimens are above 97%, and the dielectric loss is below 0.03. It was found that (K0.47Na0.47Li0.06)NbO3 prepared by MSS is compact and lead-free. The piezoelectric constant d33 is 216 pC·N-1 and the planar electromechanical coupling factor Kp is 0.352.展开更多
Background and aim:Adequate bowel preparation is important for safe and effective colonoscopy.Quality indicators(QI)for colonoscopy include achieving at least 95%completion rate and an adenoma detection rate(ADR)of at...Background and aim:Adequate bowel preparation is important for safe and effective colonoscopy.Quality indicators(QI)for colonoscopy include achieving at least 95%completion rate and an adenoma detection rate(ADR)of at least 25%in average-risk men and 15%in average-risk women aged over 50.Our aim was to investigate the impact of bowel preparation on ADR and colonoscopy completion rates.Methods:This retrospective cohort study included patients who underwent colonoscopy between January 2008 and December 2009.The main outcome measurements were ADR and colonoscopy completion rates to the cecum.Results:A total of 2519 patients was included;1030(41.0%)had excellent preparation,1145(45.5%)good-,240(9.5%)fair-,and 104(4.1%)poor preparation.Colonoscopy completion rates were significantly lower in patients with poor or fair preparation(72.1%and 75.4%,respectively)than in those with good and excellent preparation(99.7%and 99.9%,respectively;P<0.001),and significantly lower than the QI of 95%(P<0.001).ADR in men and women combined was similar in all four grades of preparation(excellent,good,fair and poor)at 24.2%vs.26.8%vs.32.1%vs.22.1%,respectively;P¼0.06.All the groups had ADR above the QI(25%for men and 15%for women)with evidence of significantly higher ADR in the women with excellent or good preparation and in men with excellent,good or fair preparation.On multivariate analysis,male gender was significantly associated with increased ADR(P<0.001),while the quality of bowel preparation did not influence ADR.Conclusions:Patients with fair and poor standards of preparation have significantly lower colonoscopy completion rates than those with excellent and good preparation.However,there was no difference in ADR between the different grades of preparation.展开更多
基金Supported by National Natural Science Foundation of China (No.10232030)Key Laboratory for Advanced Ceramics and Machining Technology,Ministry of Education,Tianjin University (No. x06050)
文摘(K0.47Na0.47Li0.06)NbO3 (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k2CO3-Na2CO3 eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at 980-1 030 ℃ were investigated. The calcined powders were examined by X-ray diffraction. The microstructure of the calcined powders and sintered bodies was observed using a scanning electron microscope (SEM).The piezoelectric constant d33 was measured using a quasi-static piezoelectric d33 meter. The planar coupling coefficient Kp was calculated by resonance-antiresonance method. The experimental data for each sample's performance indicators were the average values of 8 specimens. The relative densities of sintered specimens are above 97%, and the dielectric loss is below 0.03. It was found that (K0.47Na0.47Li0.06)NbO3 prepared by MSS is compact and lead-free. The piezoelectric constant d33 is 216 pC·N-1 and the planar electromechanical coupling factor Kp is 0.352.
文摘Background and aim:Adequate bowel preparation is important for safe and effective colonoscopy.Quality indicators(QI)for colonoscopy include achieving at least 95%completion rate and an adenoma detection rate(ADR)of at least 25%in average-risk men and 15%in average-risk women aged over 50.Our aim was to investigate the impact of bowel preparation on ADR and colonoscopy completion rates.Methods:This retrospective cohort study included patients who underwent colonoscopy between January 2008 and December 2009.The main outcome measurements were ADR and colonoscopy completion rates to the cecum.Results:A total of 2519 patients was included;1030(41.0%)had excellent preparation,1145(45.5%)good-,240(9.5%)fair-,and 104(4.1%)poor preparation.Colonoscopy completion rates were significantly lower in patients with poor or fair preparation(72.1%and 75.4%,respectively)than in those with good and excellent preparation(99.7%and 99.9%,respectively;P<0.001),and significantly lower than the QI of 95%(P<0.001).ADR in men and women combined was similar in all four grades of preparation(excellent,good,fair and poor)at 24.2%vs.26.8%vs.32.1%vs.22.1%,respectively;P¼0.06.All the groups had ADR above the QI(25%for men and 15%for women)with evidence of significantly higher ADR in the women with excellent or good preparation and in men with excellent,good or fair preparation.On multivariate analysis,male gender was significantly associated with increased ADR(P<0.001),while the quality of bowel preparation did not influence ADR.Conclusions:Patients with fair and poor standards of preparation have significantly lower colonoscopy completion rates than those with excellent and good preparation.However,there was no difference in ADR between the different grades of preparation.
