Influence of Thermodynamic Nonequilibrium on the Acoustic Properties of Gases

2005 ◽  
Vol 4 (3) ◽  
pp. 373-383 ◽  
Author(s):  
Nonna E. Molevich ◽  
Anatoly I. Klimov ◽  
Vladimir G. Makaryan

This paper is a brief review of results of experimental and theoretical studies in the field of acoustics of nonequilibrium gas-plasma media. New acoustical properties of nonequilibrium media caused by the change in sign of the second viscosity and the dispersion coefficients are considered. Such media are acoustically active. Conditions are discussed for generating new nonlinear acoustical structures.

2020 ◽  
Author(s):  
Thomas Louis-Goff ◽  
Huu Vinh Trinh ◽  
Eileen Chen ◽  
Arnold L. Rheingold ◽  
Christian Ehm ◽  
...  

A new, efficient, catalytic difluorocarbenation of olefins to give 1,1-difluorocyclopropanes is presented. The catalyst, an organobismuth complex, uses TMSCF<sub>3</sub> as a stoichiometric difluorocarbene source. We demonstrate both the viability and robustness of this reaction over a wide range of alkenes and alkynes, including electron-poor alkenes, to generate the corresponding 1,1-difluorocyclopropanes and 1,1-difluorocyclopropenes. Ease of catalyst recovery from the reaction mixture is another attractive feature of this method. In depth experimental and theoretical studies showed that the key difluorocarbene-generating step proceeds through a bismuth non-redox synchronous mechanism generating a highly reactive free CF<sub>2</sub> in an endergonic pre-equilibrium. It is the reversibility when generating the difluorocarbene that accounts for the high selectivity, while minimizing CF<sub>2</sub>-recombination side-reactions.


Author(s):  
Alexey V. Kavokin ◽  
Jeremy J. Baumberg ◽  
Guillaume Malpuech ◽  
Fabrice P. Laussy

This chapter presents experimental studies performed on planar semiconductor microcavities in the strong-coupling regime. The first section reviews linear experiments performed in the 1990s that evidence the linear optical properties of cavity exciton-polaritons. The chapter is then focused on experimental and theoretical studies of resonantly excited microcavity emission. We mainly describe experimental configuations in which stimulated scattering was observed due to formation of a dynamical condensate of polaritons. Pump-probe and cw experiments are described in addition. Dressing of the polariton dispersion and bistability of the polariton system due to inter-condensate interactions are discussed. The semiclassical and the quantum theories of these effects are presented and their results analysed. The potential for realization of devices is also discussed.


1989 ◽  
Vol 28 (13) ◽  
pp. 2552-2560 ◽  
Author(s):  
Claudio Bianchini ◽  
Franco Laschi ◽  
Dante Masi ◽  
Carlo Mealli ◽  
Andrea Meli ◽  
...  

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