A unique ligand design allows the formation of both an M L triple helicate and an M L tetrahedron (M=Ti, Ga; L=ligand based on 2,6-diaminoanthracene). Although the tetrahedron is entropically disfavored, a strong host-guest interaction with Me N is enough to drive the equilibrium towards the tetrahedron. Remarkably, the helicate can be quantitatively converted into the tetrahedron simply by addition of Me N (shown schematically).
A new kinetic model of the quiet solar wind is presented and compared with earlier exospheric, semikinetic, and hydrodynamical models. To have equal mean free paths for the protons and electrons at the baropause, the ratio of the proton temperature to the electron temperature is supposed to be Tp(ho)/Te(ho) = 0.645. With the assumption that the trapped electrons are in thermal equilibrium with those emerging from the barosphere, the electric‐field distribution is calculated to cancel the electric current and space charge in the exospheric plasma. The bulk velocity, the density, the average electron and proton temperatures, and the energy flux, which are observed at 1 AU for quiet solar‐wind conditions, are well represented by such a kinetic model. The average electron temperature is nearly independent of the bulk velocity, whereas a positive correlation between the average proton temperature and the bulk velocity is found. Consequently it is suggested that in the interplanetary medium (r>6RS) no external heating mechanism is needed to explain the observed quiet solar‐wind properties. Finally, the electric‐field calculations in this kinetic model are found to be in reasonable agreement with the empirical electric‐field values deduced from observed coronal‐density distribution.
In this paper the application of the kinetic theory to the collisionless regions of the polar and solar winds is discussed. A brief historical review is given to illustrate the evolution of the theoretical models proposed to explain the main phenomenon and observations. The parallelism between the development of the solar wind models and the evolution of the polar wind theory is stressed especially. The kinetic approaches were in both cases preceded by the hydrodynamic models, and their publication gave rise to animated controversies; later on, semikinetic and hydromagnetic approximations were introduced. A kinetic method, based on the quasi neutrality and the zero current condition in a stationary plasma with open magnetic field lines, is described. The applicability of this approach on the solar and polar winds is illustrated by comparison of the predicted results with the observations. The kinetic models are also compared with hydrodynamic ones. The validity of the criticism and remarks uttered during the Chamberlain‐Parker controversy (for the solar wind), and the dispute between Banks and Holzer on the one hand, and Dessler and Cloutier on the other (for the polar wind), are carefully analyzed. The main result of this study is that both approaches are in fact not contradictory but complementary. The classical hydrodynamic descriptions are only appropriate in the collision‐dominated region, whereas the kinetic theory can be applied only in the collision‐free domain.
We have constructed structures based on supramolecular clusters found in nature and shown that they encapsulate molecular cations. [1] The origins of supramolecular chemistry Figure 3. Kinetics of the RCM reaction of 8 e catalyzed by the Ru complexes 1 ± 4.
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