Therapeutic Effects of hiPSC-Derived Glial and Neuronal Progenitor Cells-Conditioned Medium in Experimental Ischemic Stroke in Rats

Transplantation of various types of stem cells as a possible therapy for stroke has been tested for years, and the results are promising. Recent investigations have shown that the administration of the conditioned media obtained after stem cell cultivation can also be effective in the therapy of the central nervous system pathology (hypothesis of their paracrine action). The aim of this study was to evaluate the therapeutic effects of the conditioned medium of hiPSC-derived glial and neuronal progenitor cells in the rat middle cerebral artery occlusion model of the ischemic stroke. Secretory activity of the cultured neuronal and glial progenitor cells was evaluated by proteomic and immunosorbent-based approaches. Therapeutic effects were assessed by overall survival, neurologic deficit and infarct volume dynamics, as well as by the end-point values of the apoptosis- and inflammation-related gene expression levels, the extent of microglia/macrophage infiltration and the numbers of formed blood vessels in the affected area of the brain. As a result, 31% of the protein species discovered in glial progenitor cells-conditioned medium and 45% in neuronal progenitor cells-conditioned medium were cell type specific. The glial progenitor cell-conditioned media showed a higher content of neurotrophins (BDNF, GDNF, CNTF and NGF). We showed that intra-arterial administration of glial progenitor cells-conditioned medium promoted a faster decrease in neurological deficit compared to the control group, reduced microglia/macrophage infiltration, reduced expression of pro-apoptotic gene Bax and pro-inflammatory cytokine gene Tnf, increased expression of anti-inflammatory cytokine genes (Il4, Il10, Il13) and promoted the formation of blood vessels within the damaged area. None of these effects were exerted by the neuronal progenitor cell-conditioned media. The results indicate pronounced cytoprotective, anti-inflammatory and angiogenic properties of soluble factors secreted by glial progenitor cells.     

High-output thermionic converter based on a metal-oxygen system on the collector

The results of comprehensive experimental investigations of thermionic converters with collectors containing oxygen in an adsorbed near-surface layer and capable of decreasing the barrier index below 2 eV are presented. A vanadium-doped alloy based on chromium, which was investigated in a converter in a pair with different emitters consisting of platinum and single crystal tungsten oriented along the (110) face, was examined as an example of an efficient metal-oxygen system on the collector. The emission-adsorption properties of electrodes and the output electrical characteristics, obtained under working conditions of the converter, as well as surface characteristics of the collector, such as the elemental composition temperature, and others, are described. 6 figures, 21 references. State Science Center of the Russian Federation—A. I. Leipunskii Physics and Power-Engineering Institute. Translated from Atomnaya énergiya, Vol. 89, No. 1, pp. 39–48, July, 2000.     

Mass Transfer and Friction in Near-Wall Film Flows in Conditions of High-Velocity Co-Current Gas Flow

We present the experimental research on the interaction of co-current gas flow with near-wall liquid film for gas velocities up to 300 m/s. Local parameters of near-wall liquid film are measured by using capacity-type probes. It is shown that co-current gas flow has strong influence on near-wall liquid film, leading to intensive wave formation, detachment of droplets from the film surface and their entrainment by the gas flow. Thus it is shown that the relative amount of liquid carried away by co-current gas flow is well characterized by Weber number of gas flow. A model for the motion of a film with co-current flow, connecting a thickness and velocity of the film with value of shearing stress at gas-liquid boundary, is suggested. It is shown that intensive wave formation leads to essential increase of the interphase friction value.     

Fuel components and fission products diffusion on the surface of communicating cavities of a thermionic electricity-generating channel

The diffusion of fuel components and fission products on the surface of communicating cavities of a thermionic electricity-generating channel of a nuclear power facility is studied analytically. The Arrhenius constants are determined for the electricity-generating channel. A model is developed for the diffusion of the atoms of the fuel components and fission products on the surface of fuel element cladding. The results are used to determine the negative effect of the diffusion of uranium, as the main component of the fuel, and the uranium fission products molybdenum, niobium, and zirconium on the emission-adsorption characteristics of the electrodes of the electricity-generating channel and the electrical properties of the nuclear power facility. Proposals are made for reducing the effect of the phenomenon analyzed.     

Detection of Microscopic Penetrating Flaws in Structures by Localization of Acoustic Fields Generated by Air Flows

A new spectrum analyzer of acoustic fields designed for detecting penetrating flaws is considered. The experimental testing of the apparatus is discussed.     

New-generation space thermionic nuclear power systems with out-of-core electricity generating systems

The basic problems of the development of long service life thermionic nuclear power systems for space applications for supplying power to transport power modules, intended for placing spacecraft in a geostationary orbit using electrorocket motors and for providing prolonged operation of onboard systems for up to 10–15 years, are examined. Concepts for power systems with multi- and single-element thermionic low-temperature energy-conversion systems, which are placed outside the reactor core and in which heat is delivered to the emitters using molybdenum-lithium heat pipes at 1600–1670 K, are discussed as an example. Computational results are presented for the electro- and thermophysical characteristics of electricity generating systems and power systems with different variants of the design-technological solutions, including the possibility of increasing the service life by reserving a part of the thermionic electrical power. The mass/size characteristics of the power systems with basic variants of the systems are obtained and recommendations based on research and development work are made, 8 figures, 8 references. Translated from Atomnaya énergiya, Vol. 89, No. 1, pp. 22–34, July, 2000.     

Influence of homogeneous condensation on the gasdynamics and radiation of a free carbon dioxide jet

The influence of homogeneous condensation on the gasdynamics and radiation of carbon dioxide gas during jet expansion into a vacuum is investigated experimentally and theoretically.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 1, pp. 5–10, July, 1985.