Laser-Induced Dissociation of an Energetic Polymer: A Spectroscopic Study of the Gaseous Products

Previous studies of GAP (glycidyl azido polymer) laser-induced decomposition (Propellants, ExplosiVes, Pyrotechnics 1996, 21, 258), revealed that the shock wave produced from a diluted polymer is more energetic than from the neat polymer. In this paper, direct measurement of the energy disposal into molecular products is reported using spectroscopic methods. Chemiluminescence probes electronically excited species, and laserinduced fluorescence, ground-state radicals. It is found that the initial velocity and internal energy content of small diatomic molecules is larger in some diluted polymers than in the neat one. This finding is in line with a simple model based on the assumption of a self-sustained reaction following initial laser excitation

Drawing the Line at Neglected Marine Ecosystems: Ecology of Vermetid Reefs in a Changing Ocean

Vermetid mollusks form reefs that protect coasts from erosion, regulate sediment transport, serve as carbon sinks, and provide habitat for many fish and invertebrates. This biogenic habitat is found in tropical, sub-tropical, and warmtemperate coastal areas, such as Bermuda, oceanic islands in Brazil, and Hawaii, several locations within the Caribbean and the Mediterranean. These reefs are functionally similar to tropical coral fringing reefs but are built by gregarious vermetid gastropods cemented by a crustose coralline algal species, which probably triggers their settlement. Some descriptive studies in different regions worldwide and comparisons among tropical and Mediterranean reefs contributed to show their important role as engineered habitat and biodiversity hotspots. In recent years, a dramatic decrease in the vermetid live cover was recorded in the Eastern basin of the Mediterranean, with some documented local extinctions within a few decades. Pollution and the spread of invasive species are potential threats to this animal forest and to the biodiversity it supports. Yet, the response of the vermetid reef to climate change is almost unknown, although recent experiments demonstrated high sensitivity of this snail species to ocean acidification. Hence, the ongoing rapid environmental change and increasing anthropogenic use along the coast may have detrimental effects on the remaining reefs and therefore significant ramifications for coastal systems in the Mediterranean and subtropical and warm-temperate regions. This chapter aims at filling these knowledge gaps by presenting both a short literature-based study and a set of new research paths to explore and improve conservation and research activities given the range of ecosystem services pristine vermetid reefs may provide

Electrical discharge in a nanometer-sized air/water gap observed by atomic force microscopy

10.1021/ja054225rJournal of the American Chemical Society1274415562-15567JACS