Growth in the velocity of mass transfer through the CMX membrane during its aging by operation in intense current regimes

One of the causes for the aging of membranes during their operation in electrodialysis (ED) of solutions is irreversible chemical changes in the ion exchange or reinforcement polymer due to interaction of H⁺ and OH⁻ ions (present in feed solutions or generated in the membrane system under intense current modes) with the matrix or fixed groups in the surface layer of the membranes. The reduction in current efficiency and an increase in energy consumption in the process of electrodialysis are usual consequences of these changes. It has been shown that the degradation of the ion-exchange polymer on the surface of the CMX membrane during its operation in intense current regimes results in the hydrophobization of the membrane surface, which, in turn, causes enhancement of electroconvection. As a result, the limiting current and the mass transfer coefficient of salt ions increase during membrane operation. In the case of desalination of dilute solutions, this growth can reach 50–70% in comparison with the fresh membrane.     

Experimental Study on Formation of Particle Accumulation Structures by a Thermocapillary Flow in a Deformable Liquid Column

A series of experiments has been performed under earth’s gravity to study formation of particle accumulation structures (PAS) in a supercritical flow driven by the combined effects of buoyancy and thermocapillary forces. The test flow was created in a non-isothermal cylindrical column (liquid bridge) made of n-decane and heated from above. The objective of the experiment was to answer two major questions: (1) how strong is the influence of the shape of the interface on the process of formation of PAS; (2) what temperature of the ambient air fits better for PAS to occur. Considering these questions, we developed a method based on changing both the volume of the liquid bridge and temperature at the external walls of the experimental chamber to set and to keep constant the shape of the interface and the temperature inside the setup, respectively. The experimental observations are presented in the form of diagrams in the parameters’ space showing ranges of the PAS formation. The findings show that a liquid bridge with an interface as close to the straight cylindrical as possible and surrounded by air at low temperature is the best terrain for PAS formation. The results of the chaos analysis of the recorded temperature time series and their correlation with the obtained diagrams allow for showing that accumulation of particles in coherent structures is possible only in a periodic oscillatory flow characterized by a small value of the translation error not exceeding 0.01. It is demonstrated that presence of either any spectral noise or of several modes with incommensurate frequencies makes formation of a PAS impossible.     

Effect of the form of the temperature dependence of surface tension on motion and heat transfer in a layer of liquid during local heating

The nonsteady distribution of velocity and temperature in a layer of liquid during thermoconvective motion caused by local heating is calculated. The cases of an increasing and decreasing temperature dependence of surface tension are examined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 1, pp. 27–33, July, 1989.     

Assessment of porosity and structure of powder materials based on mechanically activated Ni-Fe-NaCl charges

Electron-probe microanalysis methods were used to study the formation of structure and the distribution of various components in high-porosity powder materials during heat treatment of compacts based on Ni-Fe-NaCl charges mechanically activated in fluid media. We confirmed the hypothesis that agglomerates are formed during mechanical activation of Ni-and Fe-based composite-particle charges in fluid media. A causal relationship was established between formation of structure in compacts and structure of the high-porosity powder material after heat treatment. A technique was proposed for determining the local porosity of the sintered high-porosity powder material. The structure of the high-porosity powder material was found to consist of large pores surrounded by powder material containing pores of smaller diameter.     

Analysis of the Thermal Performance of SODI Instrument for DCMIX Configuration

There exists an instrument SODI (Selected Optical Diagnostic Instrument) on the ISS where series of the DCMIX (Diffusion Coefficients in Mixtures) experiments are conducted by members of the ESA Topical Team. The study is addressed to the performance of thermal design of SODI instrument for DCMIX configuration. We report the results on the temperature fields which were measured interferometrically both in two ground setups (one thermally optimized; the other one, the engineering model of the ISS SODI-DCMIX experiment: non optimized) and in the ISS experiment itself with the respective numerical simulations. Even though monitoring of the cell with binary mixture $THN-nC_{12}$ employs only an interferometer with one wave length instead of two for other cells with ternary mixtures, it gives valuable information about the instrument performance. Temperature and concentration fields observed during the tests in the engineering model are compared with those obtained in laboratory experiments with the same liquid, with numerical simulations and with first results from the ISS in Run #16. The thermal design of the microgravity cell, being not optimized for ground experiments, exhibits a promising performance in the weightlessness condition.     

Thermocapillary convection in a liquid bridge subjected to interfacial cooling

Influence of heat loss through interface on a supercritical three-dimensional thermoconvective flow in a long liquid bridge is numerically investigated under terrestrial conditions. A flow in a high Prandtl number liquid surrounded by an ambient gas of constant temperature is simulated for the large aspect ratio, Γ=1.8. It is shown that the heat loss plays a significant role in the flow dynamics. It modifies both the flow and the liquid temperature field. Moreover, for the relatively large aspect ratio and a high Prandtl number liquid the heat loss from interface leads to destabilization of the flow.     

Electrochemical synthesis of polythiophene–polyacrylamide composite coatings used for pseudocapacitors

Polythiophene films have been electrochemically deposited onto uncoated and coated with polyacrylamide steel mesh. It has been found that the specific capacitance of the polythiophene film deposited on a sublayer of polyacrylamide was 30% higher than of the film of polythiophene deposited on the steel mesh without the underlayer.     

Ipsilateral and Contralateral Interactions in Spinal Locomotor Circuits Mediated by V1 Neurons: Insights from Computational Modeling

We describe and analyze a computational model of neural circuits in the mammalian spinal cord responsible for generating and shaping locomotor-like oscillations. The model represents interacting populations of spinal neurons, including the neurons that were genetically identified and characterized in a series of previous experimental studies. Here, we specifically focus on the ipsilaterally projecting V1 interneurons, their possible role in the spinal locomotor circuitry, and their involvement in the generation of locomotor oscillations. The proposed connections of these neurons and their involvement in different neuronal pathways in the spinal cord allow the model to reproduce the results of optogenetic manipulations of these neurons under different experimental conditions. We suggest the existence of two distinct populations of V1 interneurons mediating different ipsilateral and contralateral interactions within the spinal cord. The model proposes explanations for multiple experimental data concerning the effects of optogenetic silencing and activation of V1 interneurons on the frequency of locomotor oscillations in the intact cord and hemicord under different experimental conditions. Our simulations provide an important insight into the organization of locomotor circuitry in the mammalian spinal cord.