Growth Response of White Spruce [Picea glauca (Moench) Voss] in Denali National Park under Warming Climate

In subarctic mountains such as Denali National Park and Preserve(DNP), vegetation shifts from alpine tundra to boreal forests caused by recent climate change are a potential threat to plant conservation and indirectly to animal habits and diversity, which could affect the experience of visitors who wish to see wildlife. The growth rate of Picea glauca (white spruce) could decrease by climate change due to drought stress, which might lead to species elimination. The shift of P. glauca towards a higher elevation would require its seedlings not only to adapt to new abiotic harsh conditions, but also to compete with other plant species that are already present

Poly(dimethylsiloxane)-poly(ethyleneoxide)-heparin block copolymers. I. Synthesis and characterization

Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), and heparin (PDMS-PEO-Hep) have been prepared via a series of coupling reactions using functionalized prepolymers, diisocyanates, and derivatized heparins. All intermediate steps of the synthesis yield quantifiable products with reactive end-groups, while the final products demonstrate bioactive, covalently bound heparin moieties. Due to the solvent systems required, commercial sodium heparin was converted to its benzyltrimethyl ammonium salt to enhance its solubility. The same procedure was applied to heparin degraded by nitrous acid in order to covalently couple it in solutions with the semitelechelic copolymers. As might be expected, this derivatization reduces the apparent bioactivity of the heparin. However, preliminary findings suggest that the bioactivity can be restored by reforming the heparin sodium salt