Freezing tolerance in an adult insect

The adult carabid beetle Pterostichus brevicornis tolerates freezing under natural conditions. Laboratory tests confirm that winter beetles tolerate temperatures below -35 degrees C, whereas summer beetles die if frozen at -6.6 degrees C. Winter beetles can be cooled to about -10 degrees C before freezing, and they thaw near -3.5 degrees C. Summer beetles thaw at -0.7 degrees C. To avoid freezing damage even in winter beetles, cooling rates must be near 20 degrees C per hour or less.     

Chemistry and chemical intermediates in supersonic free jet expansions

Short-lived intermediates often play key roles in determining the course of chemical reactions. Recently the combination of sophisticated laser techniques and supersonic free jet expansions has offered new insight into the structure and reactivity of such intermediates. Because of their extremely reactive nature the intermediates are produced in situ in the expansion. The free jet expansion provides cooling of the intermediates to very low temperatures, so that even complex organic free radicals and molecular ions can be identified and characterized. Radical-radical reactions and ionic cluster formation likewise proceed in the expansion and can be monitored by laser spectroscopy.     

Observation of transient structural-transformation dynamics in a Cu2S nanorod

The study of first-order structural transformations has been of great interest to scientists in many disciplines. Expectations from phase-transition theory are that the system fluctuates between two equilibrium structures near the transition point and that the region of transition broadens in small crystals. We report the direct observation of structural fluctuations within a single nanocrystal using transmission electron microscopy. We observed trajectories of structural transformations in individual nanocrystals with atomic resolution, which reveal details of the fluctuation dynamics, including nucleation, phase propagation, and pinning of structural domains by defects. Such observations provide crucial insight for the understanding of microscopic pathways of phase transitions.