Humidity-induced formation of water channels in supramolecular assemblies of wedge-shaped amphiphiles: the effect of the molecular architecture on the channel topology.

In supramolecular assemblies, absorption of water can assist the channel formation, similarly to biological systems and Nafion-like commercial ion-selective membranes. In this work, we investigate humidity-induced formation of water channels in wedge-shaped amphiphilic molecules, namely sodium 4'-[3'',4'',5''-tris(alkyloxy)benzoyloxy]azobenzene-4-sulfonates. The studied molecules contain a polar sulfonate group at the tip and a hydrophobic periphery composed of alkyl chains of two different lengths. Upon increasing the relative humidity (RH) the amount of absorbed water significantly increases for the mesogen with dodecyl chains as compared to the one with octyl groups. In the former case, water sorption is accompanied by a considerable enhancement of ionic conductivity and a phase transition. In particular, an increase of RH induces a transition from a lamellar to a columnar phase resulting in the formation of 1D water channels running along the axis of the supramolecular columns. For the compound with shorter alkyl chains the lamellar phase exists in the entire RH-range exhibiting pronounced swelling at high RH-values and thereby forming a 2D water channel structure. NMR diffusometry was used to address the different molecular motions in the lyotropic mesophases of the studied amphiphiles.

First measurement of the transverse spin asymmetries of the deuteron in semi-inclusive deep inelastic scattering.

First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.

[Corticofugal influences on pontine neuronal activity]. / Kortikofugal'nye vliianiia na aktivnost' neironov varolieva mosta.

Reactions of neurons of pons varolii reticular and proprial nuclei to stimulation of the frontobasal regions of the cortex (proreal, orbital and basal temporal regions) and dorsal hippocampus were studied in cat. The stimulation of various cortical structures caused phasic and rarely tonic reactions of these neurons. Primary excitation was the dominant type of reactions in the reticular nuclei and primary inhibition--in the proprial nuclei. The greatest number of responding neurons was observed during stimulation of the proreal gyrus. In the cerebro-cerebellar system the most responsible neurons were those of nucleus reticularis tegmenti pontis and ventromedial part of the pontine grey matter. The regions of dominant influence from the cortical structures were in the same zones of the pontine reticular formation, where neurons with rostral projection are localized.

[Convergence of corticofugal impulses on pontine neurons]. / Konvergentsiia kortikofugal'nykh impul'sov na neironakh varolieva mosta.

The convergence of corticofugal impulses in reticular and grisea pontis nuclei evoked by stimulation of the neocortex frontobasal regions (proreal, posterior orbital, basal temporal) as well as of the dorsal hippocampus was studied in cats narcotized by a mixture of nembutale and chloralose. Three foci of corticofugal impulse convergence were determined in the structures of pons varolii: one in the reticular formation and two in grisea pontis nuclei -- in their medial and lateral regions. Neurons with excitatory reactions are shown to dominate in the pons varolii reticular formation and those with inhibitory and mixed reactions -- in the grisea pontis. The integrative function of pons varolii nuclei in the functional connection of frontobasal zones of neocortex and hippocampus is discussed.

[Electrophysiologic analysis of cortico-pontine relationships]. / Elektrofiziologicheskii analiz kortiko-pontinnykh sviazei.

Projections of different regions of orbitofrontal and basotemporal cortex as well as of the hippocampus in the pons varolii area were studied by means of focal recording in acute experiments on cats anesthetized with nembutal and chloralose. It is shown that different formations of the frontobasal regions of the neocortex have local projections into the rostral zones of pons varolii and relatively diffuse projections into its caudal regions. The representation of the hippocampus is weaker as compared with the representation of the frontobasal region, and the focal responses are more diffuse. All the studied structures are represented in the nuclei of the pons varolii. The region of the orbitofrontal cortex is not represented in the caudal part of the reticular formation, the basotemporal cortex has no projections into brachium pontis.