Anthracene-based thiol-ene networks with thermo-degradable and photo-reversible properties

Reversible networks based on an alkenefunctionalized dimer of 9-anthracenemethanol were synthesized by photoinitiated radical thiol ene polyaddition, using either a poly(dimethylsiloxane-co-propylmercaptomethylsiloxane) or a novel aliphatic trithiol synthesized from 1,2,4trivinylcyclohexane in a simple two-step procedure. The obtained networks were analyzed using differential scanning calorimetry, dynamic mechanical analysis, polarization microscopy, X-ray diffraction, and (photo)rheology. The two types of networks showed weak endothermic transitions between 50 and 60 degrees C, which proved to originate either from melting of a crystalline anthracene-dimer phase (trithiol network) or from a liquid crystalline phase (PDMS network) based on X-ray diffraction and polarization microscopy. Using rheology, both types of networks were shown to cleanly decompose into multifunctional anthracene monomers at temperatures above 180 degrees C. Irradiation of these anthracene monomers resulted in the formation of networks having similar physical properties as the original materials

The impact of race as a risk factor for symptom severity and age at diagnosis of uterine leiomyomata among affected sisters

OBJECTIVES: To identify risk factors for uterine leiomyomata (UL) in a racially diverse population of women with a family history of UL and to evaluate their contribution to disease severity and age at diagnosis. STUDY DESIGN: We collected and analyzed epidemiological data from 285 sister pairs diagnosed with UL. Risk factors for UL-related outcomes were compared among black (n=73) and white (n=212) sister pairs using univariate and multivariate regression models. RESULTS: Black women reported an average age at diagnosis of 5.3 years younger (SE 1.1, p<0.001) and were more likely to report severe disease (OR=5.22, CI 95% 1.99–13.7, p<0.001) than white women of similar socioeconomic status. CONCLUSIONS: Self-reported race is a significant factor in the severity of UL among women with a family history of UL. Differences in disease presentation between races likely reflect underlying genetic heterogeneity. The affected sister-pair study design can address both epidemiological and genetic hypotheses about UL