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The melting and crystallization behaviors, morphology, and mechanical properties of polypropylene (PP)/surface-treated calcium sulfate (CaSO4) whisker (T-CSW), β-PP/T-CSW, and β-PP/polypropylene- graft-maleic anhydride (PP-g-MAH)/T-CSW composites had been investigated via differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), polarized light microscopy (PLM), scanning electron microscopy (SEM), and mechanical tests. We found that T-CSW was an α-nucleating agent and increased the crystallization temperatures of PP, but PP-g-MAH and high loadings of T-CSW had weakly negative effects on the crystallization rates of PP. The T-CSW restrained the formation of β-spherulites, and the spherulitic size decreased in the composites. PP-g-MAH improved the compatibility and adhesion between T-CSW and the matrix. The notched impact strength was improved, and the tensile strength was enhanced at low levels of T-CSW, while the flexural modulus was weakened for β-PP/T-CSW and β-PP/PP-g-MAH/T-CSW composites versus PP/T-CSW composites. POLYM. COMPOS., 37:2121-2132, 2016. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Why does a beneficial treatment effect on a longitudinal biomarker not translate into overall treatment benefit on survival, when the biomarker is in fact a prognostic factor of survival? In a recent exploratory data analysis in oncology, we were faced with this seemingly paradoxical result. To address this problem, we applied a theoretically principled methodology called dynamic path analysis, which allows us to perform mediation analysis with a longitudinal mediator and survival outcome. The aim of the analysis is to decompose the total treatment effect into a direct treatment effect and an indirect treatment effect mediated through a carefully constructed mediation path. The dynamic nature of the underlying methodology enables us to describe how these effects evolve over time, which can add to the mechanistic understanding of the underlying processes. In this paper, we present a detailed description of the dynamic path analysis framework and illustrate its application to survival mediation analysis using simulated and real data. The use case analysis provides clarity on the specific exploratory question of interest while the methodology generalizes to a wide range of applications in drug development where time‐to‐event is the primary clinical outcome of interest. [ABSTRACT FROM AUTHOR]