Exponent

About: Exponent is a company organization based out in Menlo Park, California, United States. It is known for research contribution in the topics: Population & Risk assessment. The organization has 1589 authors who have published 2680 publications receiving 88140 citations.

Fracture of nanoporous methyl silsesquioxane thin-film glasses

Abstract: The fracture of nanoporous methylsilsesquioxane thin-film glasses in moist air and aqueous solutions was investigated. We demonstrate the effects of controlled volume fractions of nanometer sized pores on the films resistance to fracture. Subcritical cracking accelerated by the presence of moisture, controlled pH, and hydrogen peroxide solutions is reported. Surprising changes in the near threshold growth rate behavior were observed for buffered solutions. We demonstrate that these changes are related to the unexpected diffusion of the aqueous solutions into the highly hydrophobic films. The presence of the solution changes the surface stress of the internal pore surfaces, which changes the stress state of the film. The change in film stress surrounding the crack alters the crack driving force and has profound effects on the resulting crack-growth threshold behavior.

Product Information Presentation, User Behavior, and Safety:

Abstract: A review of approximately 400 published articles, in addition to the authors' own research in the area of on-product warning label design and effectiveness, is summarized. Findings are examined for implications in the design and use of on-product warning labels for improved product safety through modification of user behavior. No scientific evidence was found to support the contention that on-product warning labels measurably increase the safety of any product. There was evidence that on-product warnings have no measurable impact on user behavior and product safety.

Active and Passive Smoking and Risk of Nasopharyngeal Carcinoma: A Population-Based Case-Control Study in Southern China.

Abstract: The magnitude and patterns of associations between smoking and risk of nasopharyngeal carcinoma (NPC) in high-incidence regions remain uncertain. Associations with active and passive tobacco smoking were estimated using multivariate logistic regression in a population-based case-control study of 2,530 NPC cases and 2,595 controls in Guangdong and Guangxi, southern China, in 2010-2014. Among men, risk of NPC was significantly higher in current smokers compared with never smokers (odds ratio (OR) = 1.32, 95% confidence interval (CI): 1.14, 1.53) but not in former smokers (OR = 0.92, 95% CI: 0.73, 1.17). Risk increased with smoking intensity (per 10 cigarettes/day, OR = 1.09, 95% CI: 1.03, 1.16), smoking duration (per 10 years, OR = 1.11, 95% CI: 1.06, 1.16), and cumulative smoking (per 10 pack-years, OR = 1.08, 95% CI: 1.04, 1.12). Risk decreased with later age at smoking initiation (per year, OR = 0.97, 95% CI: 0.96, 0.98) but not greater time since smoking cessation. Exposures to passive smoking during childhood (OR = 1.24, 95% CI: 1.03, 1.48) and from a spouse during adulthood (OR = 1.30, 95% CI: 1.03, 1.63) were independently associated with increased NPC risk in never-smoking men and women, but exposure-response trends were not observed. In conclusion, active and passive tobacco smoking are associated with modestly increased risk of NPC in southern China; risk is highest among long-term smokers.

Mechanical Properties, Oxidation, and Clinical Performance of Retrieved Highly Cross-Linked Crossfire Liners After Intermediate-Term Implantation

Abstract: Sixty Crossfire (Stryker Orthopaedics, Mahwah, NJ) liners were consecutively revised after an average of 2.9 years (range, 0.01-8.0 years) for reasons unrelated to wear or mechanical performance of the polyethylene. Femoral head penetration was measured directly from 42 retrievals implanted for more than 1 year. Penetration rate results (0.04 mm/y, on average; range, 0.00-0.13 mm/y) confirmed decreasing wear rates with longer in vivo times. Overall, we observed oxidation levels at the bearing surface of the 60 liners (0.5, on average; range, 0.1-1.7) comparable to those of nonimplanted liners (0.5, on average; range, 0.3-1.1) and preservation of mechanical properties. We also measured elevated oxidation of the rim (3.4, on average; range, 0.2-8.8) that was correlated with implantation time. Rim surface damage, however, was observed in only 3 (5%) of 60 cases. Retrieval analysis of the 3 rim-damaged liners did not reveal an association between surface damage and the reasons for revision.