Сравнительное исследование электрохромных свойств слоев полианилин-поликислота, нанесенных методами спрей-распыления и полива с добавлением углеродных нанотрубок

The influence of coating method (spray-coating or drop-casting onto horizontal substrate) on the electrochromic characteristics of the layers of water-soluble polyaniline-polyacid complex was investigated. It was shown that in case of addition of single-wall nanotubes the polyaniline-polyacid layers prepared by scalable spray-coating technology demonstrate high coloration speed an electrochromic efficiency.

Evaporation of multiple droplets

We derive an accurate estimate for the diffusive evaporation rates of multiple droplets of different sizes and arbitrary contact angles placed on a horizontal substrate. The derivation, which is based on a combination of Green's second identity and the method of reflections, simply makes use of the solution for the evaporation of a single droplet. The theoretical results can serve as a guide for future computational and experimental studies on the collective evaporation of arrays of droplets, as well as similar multi-body, diffusion-dominated transport problems.

Evaluation of force feedback in walking using joint torques as 'naturalistic' stimuli

Control of adaptive walking requires the integration of sensory signals of muscle force and load. We have studied how mechanoreceptors (tibial campaniform sensilla) encode 'naturalistic' stimuli derived from joint torques of stick insects walking on a horizontal substrate. Previous studies showed that forces applied to the legs using the mean torque profiles of a proximal joint were highly effective in eliciting motor activities. However, substantial variations in torque direction and magnitude occurred at the more distal femoro-tibial joint, which can generate braking or propulsive forces and provide lateral stability. To determine how these forces are encoded, we utilized torque waveforms of individual steps that had maximum values in stance in the directions of flexion or extension. Analysis of kinematic data showed that the torques in different directions tended to occur in different ranges of joint angles. Variations within stance were not accompanied by comparable changes in joint angle but often reflected vertical ground reaction forces and leg support of body load. Application of torque waveforms elicited sensory discharges with variations in firing frequency similar to those seen in freely walking insects. All sensilla directionally encoded the dynamics of force increases and showed hysteresis to transient force decreases. Smaller receptors exhibited more tonic firing. Our findings suggest that dynamic sensitivity in force feedback can modulate ongoing muscle activities to stabilize distal joints when large forces are generated at proximal joints. Further, use of 'naturalistic' stimuli can reproduce characteristics seen in freely moving animals that are absent in conventional restrained preparations.

Analytical Estimates of the Water Drop Spreading Process with Percolation Effect

To solve the problems of active influence on thunderstorm clouds, the physical mechanism of artificial formation of water and ice germs in the cloud environment is theoretically studied. Based on the Gibbs-Vollmer theory of new phase formation, it follows that the defining parameters in the formation of embryos are the interphase energies at the vapor - water - reagent boundaries and the wetting edge angle. The active process of water spreading over a water-soluble flat horizontal substrate is studied using analytical methods. It is established that the process of interfacial interaction is metastable, in addition, the spreading process is characterized by the presence of direct contact zone between two phases in which the formation of a new compound is delayed. A theoretical evaluation of individual parameters of the system under gravitational spreading without the influence of other external fields is made. Two problems were solved: determining the dynamics of the free surface of the liquid phase and finding the boundaries of liquid propagation in the substrate. An analytical expression defining the contact angle is obtained. It is shown that the expressions defining the process main parameters of spreading a drop with simultaneous impregnation of the substrate, accompanied by a loss of mass of the liquid through the contact spot on the border of the two phases, are almost equivalent to the relations describing the process of mass loss when spreading an easily evaporating liquid.

ON CALCULATION OF DRYING KINETICS OF THERMOLABILE LIQUID DISPERSED PRODUCTS ON SUBSTRATES

For the drying process of a liquid dispersed product layer on a horizontal substrate, a model for the formation of a solid phase particle residue is proposed. The model is based on the construction of a fractal cluster on a bounded spatial lattice according to given rules. The model is constructed on the basis of ideas about the mechanism of interaction of particles during the existence of a layer of free liquid in the drying product. The fractal model, which has the property of self-similarity of the forming structure, allows modeling spatial structures on bounded lattices and spreading the data obtained on bounded lattices to the entire volume of the simulated residue. The article provides a brief overview of the main works related to the application of the fractal concept in the modeling of micro and macroscopic structures arising during the drying of liquid products. It is shown that in order to calculate the kinetics of drying liquid dispersed products on substrates, in the case of the formation of a certain layer of surface film and the formation of a certain spatial structure of solid particles, an important task is to determine the critical moisture content. The proposed model allows modeling layers with fractal dimension lying in the range from 1.64 to 2. This range corresponds to layers in the porosity range from layers with dense monodisperse particle stacking with a coordination number of 12, to structures similar to dendrite fractals, with porosity much higher than the ordered simple cubic particle stacking. The results of fractal cluster modeling and comparison of calculated and experimental values of porosity and critical moisture content obtained in the process of drying a suspension of optical bleach CD-2 and polymethylene-B-naphthalene sulfonate under different modes of convective drying of the product layer on a fluoroplastic horizontal substrate as products characterized by a close value of the initial concentration of the solid phase (≈12%), but different values of particle sizes and the obtained values of the fractal dimension of the surface film and the dry residue are presented.

Multi-scale tarsal adhesion kinematics of freely-walking dock beetles

In this experimental study, living dock beetles are observed during their free upside-down walk on a smooth horizontal substrate. Their weight is balanced by the adhesion of hairy structures present on their tarsomeres. The motions involved in the attachment and detachment of these structures were characterized by simultaneously imaging the beetle from the side at the body scale, and from the top at the scale of a single tarsal chain. The observed multi-scale three-dimensional kinematics of the tarsi is qualitatively described, then quantified by image processing and physically modelled. A strong asymmetry is systematically observed between attachment and detachment kinematics, in terms of both timing and directionality.

High Isolation Dual-Polarized Patch Antenna with Hybrid Ring Feeding

This paper presents a hybrid ring feeding dual-polarized patch antenna with high isolation in a wide working band. The proposed antenna consists of a circular radiating patch printed on the upper horizontal substrate, two pairs of Γ shaped strips printed on two vertical substrates, and a hybrid ring feeding network printed on the lower two horizontal substrates. The proposed antenna adopts Γ shape strips coupled feeding structure to achieve a wide operating band. Furthermore, a hybrid ring feeding structure with high isolation in a wide bandwidth, which is firstly proposed, is applied as feeding network. When one port is excited, the feeding network can realize twice the power cancellation. Thus, high ports isolation characteristics can be obtained. A prototype of the proposed antenna is fabricated and measured. Measured results show that the 10 dB reflection coefficient bandwidths of the two ports are both about 38.7%, with port isolation higher than 40 dB through most of the band, and the cross-polarizations are below −24 dB.