Paracrine and Autocrine Effects of VEGF Are Enhanced in Human eMSC Spheroids

The mechanisms underlying the therapeutic potential of MSCs are the focus of intense research. We studied human MSCs isolated from desquamated endometrium (eMSCs), which, as previously shown, have high regenerative potential in various disease models. The aim was to evaluate the role of secreted VEGF in stimulating angiogenesis and maintaining eMSC viability and migration, which is important for improving the therapeutic properties of MSCs. We compared three eMSC cultures differing in the level of VEGF secretion: 3D spheroids, monolayer eMSCs, and monolayer eMSCs with VEGF knockdown. Spheroid eMSCs produced higher amounts of VEGF and had the strongest paracrine effect on HUVEC. eMSCs with VEGF knockdown did not stimulate angiogenesis. Monolayered eMSCs expressed VEGFR1, while spheroid eMSCs expressed both VEGFR1 and VEGFR2 receptors. The knockdown of VEGF caused a significant decrease in the viability and migration of eMSCs. eMSCs from 3D spheroids enhanced proliferation and migration in response to exogenous VEGF, in contrast to monolayered eMSCs. Our results suggest that the VEGF–VEGFR1 loop appears to be autocrine-involved in maintaining the viability of eMSCs, and VEGFR2 expression enhances their response to exogenous VEGF, so the angiogenic potential of eMSC can be up- or downregulated by intrinsic VEGF signals.     

Direct Measurement of Rock Pressure in Mine Conditions by Hydraulic Fracturing Method

An analysis is performed for the secondary opening of the preliminarily created hydraulic fracturing crack under injection of filler with plastic properties. It is shown that this injection scheme ensures the possibility of direct measurement of rock pressure.     

Influence of condensation on the stability of a liquid film moving under the effect of gravity and turbulent vapor flow

The linear stability of condensate film flowing on an inclined isothermal plate under action of gravity and turbulent vapor flow was the subject of study. The cases of cocurrent and countercurrent flow of two phases were considered at an arbitrary inclination of the plane. The first part of this work deals with stationary film flow. The impact of vapor flow on the film is described by a given shear stress on the interface with account for the transverse mass flux due to phase transition. The integral method gives the analytical solution for distribution of film thickness along the plane (with and without account for film inertia) at different inclination angles. The second part of paper deals with linear stability of stationary film flow. The fluctuation of shear stress on the surface was calculated using the quasilaminar model. The two-wave equation for film thickness with phase transition and dispersion formulas were derived. The results of effect of condensation on film stability are presented for a wide range of flow parameters.     

The cellular fatty acid composition of bacteria in the family Vibrionaceae

It is shown that strains of Vibrio cholerae of serovar O1, biovar eltor, subtype Ogawa, museum strains V. cholerae of serovar O1 and NAG-vibrios (isolated from various sources: sea, river and sewage water, canal water and people) possess identical composition of cell fatty acids with prevailing hexadecenoic, hexadecanoic and octadecenoic acids. Being identical, fatty acid profiles of V. parahaemolyticus and V. alginolyticus, are close to that of V. cholerae differing from the latter mainly by the higher content of dodecanoic acid. Similarity of Aeromonas sp. and Vibrio strains in the fatty acid composition proves phylogenetic relation-ship of these bacteria. Fatty acid composition of Plesiomonas shigelloides cells characterized by the presence of methylenhexadecanoic acid as well as by similarity with Vibrio and Aeromonas by the content of most fatty acids confirms a supposition of R. R. Colwell on the intermediate status of genus Plesiomonas between the families Enterobacteriaceae and Vibrionaceae. Independent of the growth medium, the strains Vibrio. Aeromonas and Plesiomonas preserved a fatty-acid profile, inherent in them, with variations mainly in the content of fatty acids with the odd number of carbon atoms. Allowing for relative stability of fatty acid composition and its peculiarity in certain taxonomic groups of the studied bacteria, the above test may be used as additional objective criterion to identify the representatives of Vibrionaceae family.     

Acidic and catalytic properties of dealuminated zeolite Y treated with zirconyl nitrate solution

Structure, the constitution of a surface hydroxyl layer, and the acid properties and catalytic activity in n-hexane conversion were studied for dealuminated zeolites Y modified with zirconyl nitrate to have a zirconium loading of 0.2, 0.4, and 0.8 wt %. After dealumination with ammonium hexafluorosilicate solution and exchange for NH⁺ ₄, the initial zeolites were calcined at 500–550°C and washed with an acid or alkali solution. The investigation techniques used were X-ray diffraction, thermal analysis, IR spectroscopy, X-ray photoelectron spectroscopy, and temperature-programmed ammonia desorption. It was found that the introduction of zirconium increased the relative amount of strong acid sites, thus increasing the yield of n-hexane cracking products.     

Dielectric relaxation of epoxy polymer in composites cured in an electric field

Results of a study of the effect of various fillers (discrete aluminum-oxide fibers and powdered barium titanate) on the molecular mobility of the epoxy polymer in composites cured under the action of an electric field are given. Institute of General and Inorganic Chemistry, Academy of Sciences of Belarus, Minsk, Belarus. Translated from Inzhenerno-Fisicheskii Zhurnal, Vol. 69, No. 4, pp. 589–597, July–August, 1996.     

Electrodiffusion diagnostics of wall shear stresses in impinging jets

The electrodiffusion method of flow diagnostics was applied to the measurement of the wall shear stresses and turbulent characteristics in the vicinity of the stagnation point in impinging jets. The wall shear stress vector was determined by a double electrochemical probe consisting of two electrodes separated by a thin insulation gap. The impingement of an axisymmetric jet on a flat plate at normal incidence and the reattachment of the plane jet to an adjacent solid surface due to the Coanda effect were studied. The influence of injection and suction on the two-dimensional jet reattachment is described. This paper was presented at the International Workshop on Electrodiffusion Diagnostics of Flows held in Dourdan, France, May 1993.