Mechanically activated rupture of single covalent bonds: evidence of force induced bond hydrolysis.

We have used temperature-dependent single molecule force spectroscopy to stretch covalently anchored carboxymethylated amylose (CMA) polymers attached to an amino-functionalized AFM cantilever. Using an Arrhenius kinetics model based on a Morse potential as a one-dimensional representation of covalent bonds, we have extracted kinetic and structural parameters of the bond rupture process. With 35.5 kJ mol−1, we found a significantly smaller dissociation energy and with 9.0 × 102 s−1 to 3.6 × 103 s−1 also smaller Arrhenius pre-factors than expected for homolytic bond scission. One possible explanation for the severely reduced dissociation energy and Arrhenius pre-factors is the mechanically activated hydrolysis of covalent bonds. Both the carboxylic acid amide and the siloxane bond in the amino-silane surface linker are in principle prone to bond hydrolysis. Scattering, slope and curvature of the scattered data plots indicate that in fact two competing rupture mechanisms are observed

Interdisciplinary progress in approaches to address social-ecological and ecocultural systems

SUMMARYThe emergent human cultures have shaped, and in turn been shaped by, local ecosystems. Yet humanity's intense modification of the environment has resulted in dramatic worldwide declines in natural and cultural capital. Social-ecological systems are becoming more vulnerable through the disruption of livelihoods, governance, institutions, resources and cultural traditions. This paper reviews the environmental sub-disciplines that have emerged to seek solutions for conservation and maintenance of the resilience of social-ecological systems. It shows that a central component is engagement with the knowledges of people within their contexts. Local knowledges of nature (traditional, indigenous, local ecological knowledge and ecoliteracy) are used by place-based cultures to guide actions towards nature. The importance of new engagements between different knowledges is now becoming more widely recognized by scientific institutions. Yet there still exist many false dualisms (for example local knowledge versus science) which tend to emphasize a superiority of one over the other. Ecocultures retain or strive to regain their connections with the environment, and thus improve their own resilience. Revitalization projects offer ways to connect knowledge with action to produce optimal outcomes for both nature and culture, suggesting that systems can be redesigned by emphasis on incorporation of local and traditional knowledge systems.</jats:p