Dual mechanism of modulation of NaV1.8 sodium channels by ouabain.

In the primary sensory neuron, ouabain activates the dual mechanism that modulates the functional activity of NaV1.8 channels. Ouabain at endogenous concentrations (EO) triggers two different signaling cascades, in which the Na,K-ATPase/Src complex is the EO target and the signal transducer. The fast EO effect is based on modulation of the NaV1.8 channel activation gating device. EO triggers the tangential signaling cascade along the neuron membrane from Na,K-ATPase to the NaV1.8 channel. It evokes a decrease in effective charge transfer of the NaV1.8 channel activation gating device. Intracellular application of PP2, an inhibitor of Src kinase, completely eliminated the effect of EO, thus indicating the absence of direct EO binding to the NaV1.8 channel. The delayed EO effect probably controls the density of NaV1.8 channels in the neuron membrane. EO triggers the downstream signaling cascade to the neuron genome, which should result in a delayed decrease in the NaV1.8 channels' density. PKC and p38 MAPK are involved in this pathway. Identification of the dual mechanism of the strong EO effect on NaV1.8 channels makes it possible to suggest that application of EO to the primary sensory neuron membrane should result in a potent antinociceptive effect at the organismal level.

Atomic force microscopy bending tests of a suspended rod-shaped object: Accounting for object fixing conditions.

The technique of atomic force microscopy (AFM) bending tests of a suspended nano-object (scroll, tube, rod) makes it possible to calculate the Young's modulus of the material it is made of based on experimental data. However, the calculation results involve a large error due to uncertain conditions (console or bridge) of fixing the test object. One of the ways to reduce this error is based on the theoretical consideration of consoles or bridges as beams with one or two ends resting on Winkler elastic foundations. The beam bending problems have been solved in both cases using Krylov's functions. This has allowed for developing an approach to the analytical identification of fixing conditions and including them in the calculations. The application of the approach is illustrated by AFM measurements of the Young's modulus of MgNi_{2}Si_{2}O_{5}(OH)_{4} nanoscrolls.

Thermal Treatment Impact on the Mechanical Properties of Mg3Si2O5(OH)4 Nanoscrolls.

A group of phyllosilicate nanoscrolls conjoins several hydrosilicate layered compounds with a size mismatch between octahedral and tetrahedral sheets. Among them, synthetic Mg3Si2O5(OH)4 chrysotile nanoscrolls (obtained via the hydrothermal method) possess high thermal stability and mechanical properties, making them prospective composite materials fillers. However, accurate determination of these nano-objects with Young's modulus remains challenging. Here, we report on a study of the mechanical properties evolution of individual synthetic phyllosilicate nanoscrolls after a series of heat treatments, observed with an atomic force microscopy and calculated using the density functional theory. It appears that the Young's modulus, as well as shear deformation's contribution to the nanoscrolls mechanical behavior, can be controlled by heat treatment. The main reason for this is the heat-induced formation of covalent bonding between the adjacent layers, which complicate the shear deformation.

Characterization of silicon heterojunctions for solar cells.

Conductive-probe atomic force microscopy (CP-AFM) measurements reveal the existence of a conductive channel at the interface between p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) as well as at the interface between n-type a-Si:H and p-type c-Si. This is in good agreement with planar conductance measurements that show a large interface conductance. It is demonstrated that these features are related to the existence of a strong inversion layer of holes at the c-Si surface of (p) a-Si:H/(n) c-Si structures, and to a strong inversion layer of electrons at the c-Si surface of (n) a-Si:H/(p) c-Si heterojunctions. These are intimately related to the band offsets, which allows us to determine these parameters with good precision.