The development of convective instability during SESAME, 1979

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Meteorology and Physical Oceanography, 1983.Microfiche copy available in Archives and Science.Bibliography: p. 307-310.by Frank Parker Colby.Ph.D

Hierarchical Sticker and Sticky Chain Dynamics in Self-Healing Butyl Rubber Ionomers

We present a detailed comparison of the microscopic dynamics and the macroscopic mechanical behavior of novel butyl rubber ionomers with tunable dynamics of sparse sticky imidazole-based sidegroups that form clusters of about 20 units separated by essentially unperturbed chains. This material platform shows promise for application as self-healing elastomers. Size and thermal stability of the ionic clusters were probed by small-angle X-ray scattering, and the chain and sticker dynamics were studied by a combination of broadband dielectric spectroscopy (BDS) and advanced NMR methods. The results are correlated with the rheological behavior characterized by dynamic-mechanical analysis (DMA). While the NMR-detected chain relaxation and DMA results agree quantitatively and confirm relevant aspects of the sticky-reptation picture on a microscopic level, we stress and explain that apparent master curves are of limited use for such a comparison. The cluster-related relaxation time detected by BDS is much shorter than the elastic chain relaxation time, although the weak conductivity does follow the latter. The systematic trends across the sample series suggest that all relaxations are dominated by a cluster-related activation barrier, but also that the BDS-based cluster relaxation does not seem to be directly associated with the effective sticker lifetime. Nonlinear stress-strain experiments demonstrate a reduction of sticker lifetime on stretching and that the stored stress and the elastic recovery depend on the deformation rate. © 2019 American Chemical Society

Hierarchical Sticker and Sticky Chain Dynamics in Self-Healing Butyl Rubber Ionomers

We present a detailed comparison of the microscopic dynamics and the macroscopic mechanical behavior of novel butyl rubber ionomers with tunable dynamics of sparse sticky imidazole-based sidegroups that form clusters of about 20 units separated by essentially unperturbed chains. This material platform shows promise for application as self-healing elastomers. Size and thermal stability of the ionic clusters were probed by small-angle X-ray scattering, and the chain and sticker dynamics were studied by a combination of broadband dielectric spectroscopy (BDS) and advanced NMR methods. The results are correlated with the rheological behavior characterized by dynamic-mechanical analysis (DMA). While the NMR-detected chain relaxation and DMA results agree quantitatively and confirm relevant aspects of the sticky-reptation picture on a microscopic level, we stress and explain that apparent master curves are of limited use for such a comparison. The cluster-related relaxation time detected by BDS is much shorter than the elastic chain relaxation time, although the weak conductivity does follow the latter. The systematic trends across the sample series suggest that all relaxations are dominated by a cluster-related activation barrier, but also that the BDS-based cluster relaxation does not seem to be directly associated with the effective sticker lifetime. Nonlinear stress-strain experiments demonstrate a reduction of sticker lifetime on stretching and that the stored stress and the elastic recovery depend on the deformation rate. © 2019 American Chemical Society

Hierarchical Sticker and Sticky Chain Dynamics in Self-Healing Butyl Rubber Ionomers

We present a detailed comparison of the microscopic dynamics and the macroscopic mechanical behavior of novel butyl rubber ionomers with tunable dynamics of sparse sticky imidazole-based sidegroups that form clusters of about 20 units separated by essentially unperturbed chains. This material platform shows promise for application as self-healing elastomers. Size and thermal stability of the ionic clusters were probed by small-angle X-ray scattering, and the chain and sticker dynamics were studied by a combination of broadband dielectric spectroscopy (BDS) and advanced NMR methods. The results are correlated with the rheological behavior characterized by dynamic-mechanical analysis (DMA). While the NMR-detected chain relaxation and DMA results agree quantitatively and confirm relevant aspects of the sticky-reptation picture on a microscopic level, we stress and explain that apparent master curves are of limited use for such a comparison. The cluster-related relaxation time detected by BDS is much shorter than the elastic chain relaxation time, although the weak conductivity does follow the latter. The systematic trends across the sample series suggest that all relaxations are dominated by a cluster-related activation barrier, but also that the BDS-based cluster relaxation does not seem to be directly associated with the effective sticker lifetime. Nonlinear stress-strain experiments demonstrate a reduction of sticker lifetime on stretching and that the stored stress and the elastic recovery depend on the deformation rate. © 2019 American Chemical Society

Hierarchical Sticker and Sticky Chain Dynamics in Self-Healing Butyl Rubber Ionomers

We present a detailed comparison of the microscopic dynamics and the macroscopic mechanical behavior of novel butyl rubber ionomers with tunable dynamics of sparse sticky imidazole-based sidegroups that form clusters of about 20 units separated by essentially unperturbed chains. This material platform shows promise for application as self-healing elastomers. Size and thermal stability of the ionic clusters were probed by small-angle X-ray scattering, and the chain and sticker dynamics were studied by a combination of broadband dielectric spectroscopy (BDS) and advanced NMR methods. The results are correlated with the rheological behavior characterized by dynamic-mechanical analysis (DMA). While the NMR-detected chain relaxation and DMA results agree quantitatively and confirm relevant aspects of the sticky-reptation picture on a microscopic level, we stress and explain that apparent master curves are of limited use for such a comparison. The cluster-related relaxation time detected by BDS is much shorter than the elastic chain relaxation time, although the weak conductivity does follow the latter. The systematic trends across the sample series suggest that all relaxations are dominated by a cluster-related activation barrier, but also that the BDS-based cluster relaxation does not seem to be directly associated with the effective sticker lifetime. Nonlinear stress-strain experiments demonstrate a reduction of sticker lifetime on stretching and that the stored stress and the elastic recovery depend on the deformation rate. © 2019 American Chemical Society

Concept 3

Concept III, the publication of Syracuse University School of Architecture of 1964, is devoted to the subject which occupies most of the time and hopefully much of the thought of its students: architectural education

Winter 1972

The Mode of Action of Arsenicals in the Soil by Cecil F. Kerr (page 3) The Golf Course Superintendent: A Job Description (5) Factors Affecting Carbohydrate Reserves of Cool Season Turfgrasses by L.J. Zanoni, L. F. Michelson, W.G. COlby, and M. Drake (6) Turf Bulletin\u27s Photo Quiz by Frederick G. Cheney (9) A Close Look at TCDD (10) Environmental News--Environmental Protection Agency Cancels Registration of Herbicide Amitrole (11) Homeowner\u27s Section--Crabgrass in Perspective by R.A. Peters (12) Merion Tees--Maintenance Suggestions (14) Use of Ammonium Sulfate in Fluid Fertilizers by Frank P. Achorn and W.C. Scott, Jr. (15) River Ecology and the Impact on Man (17) To Roll or Not to Roll (18) Editorial--Talkin\u27 Turfie (24

Challenges for identifying the neural mechanisms that support spatial navigation: the impact of spatial scale.

Spatial navigation is a fascinating behavior that is essential for our everyday lives. It involves nearly all sensory systems, it requires numerous parallel computations, and it engages multiple memory systems. One of the key problems in this field pertains to the question of reference frames: spatial information such as direction or distance can be coded egocentrically-relative to an observer-or allocentrically-in a reference frame independent of the observer. While many studies have associated striatal and parietal circuits with egocentric coding and entorhinal/hippocampal circuits with allocentric coding, this strict dissociation is not in line with a growing body of experimental data. In this review, we discuss some of the problems that can arise when studying the neural mechanisms that are presumed to support different spatial reference frames. We argue that the scale of space in which a navigation task takes place plays a crucial role in determining the processes that are being recruited. This has important implications, particularly for the inferences that can be made from animal studies in small scale space about the neural mechanisms supporting human spatial navigation in large (environmental) spaces. Furthermore, we argue that many of the commonly used tasks to study spatial navigation and the underlying neuronal mechanisms involve different types of reference frames, which can complicate the interpretation of neurophysiological data

Prospectus, January 28, 1991

https://spark.parkland.edu/prospectus_1991/1001/thumbnail.jp