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A ZrO 2 nanoparticle strengthened lead-free Sn-3.5Ag-ZrO 2 solder was prepared by mechanically stirring ZrO 2 nanoparticles into the molten melt of eutectic Sn-3.5Ag alloy. The influence of ZrO 2 nanoparticles on the eutectic solidification process, in particular, the formation of Ag 3 Sn intermetallic compounds (IMCs) and the associated microstructure that forms and microhardness of Sn-3.5Ag solder, was systematically investigated. The addition of ZrO 2 nanoparticles significantly refined the size of Ag 3 Sn IMCs due to the strong adsorption effect of the ZrO 2 nanoparticles. The refined Ag 3 Sn IMCs increase the Vicker's microhardness of the prepared Sn-3.5Ag-ZrO 2 solder, which corresponds well with the prediction of the classic theory of dispersion strengthening.

ObjectivesSeveral preference-based health-related quality of life (HRQoL) instruments have been published and widely used in different populations. However no consensus has emerged regarding the most appropriate instrument in therapeutic area of stable angina. This study compared and validated the psychometric properties of two generic preference-based instruments, the EQ-5D and SF-6D, among Chinese stable angina patients.MethodsConvergent validity of the EQ-5D and SF-6D was examined with eight a priori hypotheses from stable angina patients in conjunction with Seattle Angina Questionnaire (SAQ). Responsiveness was compared using the effect size (ES), relative efficiency (RE) and receiver operating characteristic (ROC) curves. Agreement between the EQ-5D and SF-6D was tested using intra-class correlation coefficient (ICC) and Bland-Altman plot. Factors affecting utility difference were explored with multiple linear regression analysis.ResultsIn 411 patients (mean age 68.08 ± 11.35), mean utility scores (SD) were 0.78 (0.15) for the EQ-5D and 0.68 (0.12) for the SF-6D. Validity was demonstrated by the moderate to strong correlation coefficients (Range: 0.368-0.594, P< 0.001) for five of the eight hypotheses in both the EQ-5D and SF-6D. There were no serious floor effects for the EQ-5D and SF-6D, but ceiling effects for the EQ-5D were large. The areas under ROC of them all exceeded 0.5 (0.660-0.814, P< 0.001). The SF-6D showed a better discriminative capacity (ES: 0.573 to 1.179) between groups with different stable-angina-specific health status than the EQ-5D (ES: 0.426 to 1.126). RE suggested that the SF-6D (RE: 44.8 to 177.8%) was more efficient than the EQ-5D except for physical function. Poor agreement between them was observed with ICC (0.448, P< 0.001) and Bland-Altman plot analysis. Multiple liner regression showed that clinical variables significantly (P< 0.05) influenced differences in utility scores between the EQ-5D and SF-6D.ConclusionsBoth EQ-5D and SF-6D are valid and sensitive preference-based HRQoL instruments in Chinese stable angina patients. The SF-6D may be a more effective tool with lower ceiling effect and greater sensitivity. Further study is needed to compare other properties, such as reliability and longitudinal response.

ObjectivesTo compare health-related quality of life (HRQoL) between patients with stable angina and the general population in China and to examine factors associated with HRQoL among patients with stable angina.MethodsA cross-sectional HRQoL survey of stable angina patients recruited from 4 hospitals (n = 411) and the general population recruited from 3 Physical Examination Centers (n = 549) was conducted from July to December, 2011 in two large cities, Tianjin and Chengdu. HRQoL was assessed using the EQ-5D, EQ-VAS, and SF-6D instruments. The health status specific to patients with stable angina was assessed using the Seattle Angina Questionnaire (SAQ). Information on socio-demographic, clinical, and lifestyle factors were also collected. Nested regressions were performed to explore how these factors were associated with HRQoL in patients with stable angina.ResultsCompared with the general population (44.2±10 years, 49.9% females), stable angina patients (68.1±12 years, 50.4% females) had significantly lower HRQoL scores in EQ-5D utility index (0.75±0.19 vs. 0.90±0.20, p<0.05), SF-6D utility index (0.68±0.12 vs. 0.85±0.11, p<0.05), and EQ-VAS (71.2±12.3 vs. 83.9±10.9, p<0.05). The differences remained (−0.05 for EQ-5D, −9.27 for EQ-VAS and −0.13 for SF-6D) after controlling for socio-economic characteristics. SAQ scores showed that stable angina patients experienced impaired disease-specific health status, especially in angina stability (40.5±34.6). Nested regressions indicated stable angina-specific health status explained most of the variation in HRQoL, among which disease perception, physical limitation, and angina stability were the strongest predictors. More physical exercise and better sleep were positively related with HRQoL.ConclusionsCompared to the general population, stable angina patients were associated with lower HRQoL and lower health utility scores, which were largely impacted by clinical symptoms. Further studies are needed to characterize the influence of geographic and cultural factors on the variations of health-related utility in stable angina patients.

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