The Effect of pH on Stability of an Isolation Barrier Made of Dolomite Post-Floatation Waste

Dolomite post-floatation waste has been proposed as an alternative material for the construction of separation barriers. The aim of this study was to determine the effect of the pH of leaching solutions on the stability of such barriers. The present research included the determination of selected physical and chemical properties of waste, i.e., density, grain composition, and filtration coefficient. Column tests of leaching by solutions of different pH values modeling varying environmental conditions were performed. Selected ions were determined in the eluates. Grain analyses were carried out for the column material after leaching to determine the changes in grain composition of dolomite due to washing with leaching solutions. The determined value of the filtration coefficient is 6.52 × 10−9 m∙s−1, which confirms the impermeability of the waste. The material is fine-grained, with a grain diameter of d ≤ 200 µm. During leaching, a decrease in the content of the analyzed ions and the diameter of grains and their movement down the barrier, resulting in its sealing, was observed. The central part of all columns showed more grains with a diameter of 7 μm, which is probably due to secondary precipitation of CaSO4. Irrespective of the initial pH of the leaching solution, the reaction of all eluates obtained was slightly alkaline (pH 7.52–8.20). Dolomite post-floatation waste has properties that ensure the tightness and durability of the separation barrier, which, combined with its ability to alkalize solutions and the sealing process, ensures its effectiveness.

Mathematical modeling of water purification in a bioplato filter

A mathematical model of filtration taking into account clogging and suffusion in the bioplato filter system in the two-dimensional case was built. The constructed mathematical model takes into account the physical effects of the dynamic change of porosity and the dependence of the filtration coefficient on the concentration of contaminants, which is not in the known analogues

A Theoretical Analysis of Profile Conformance Improvement Due to Suspension Injection

This study is focused on a solution for the problem of suspension penetration in a porous formation. Such a solution forms the basis of injection profile diversion technology for oil reservoir sweep improvement. A conventional model of deep-bed suspension flow was used to describe the suspension injection process. The suspension slug was followed by water injection, and the inflow injection profile before and after treatment was investigated. For the first time, the criteria that determine the effectiveness of the inflow profile improvement process are introduced. The effect of the suspension filtration coefficient on the particle penetration depth was studied. A specific filtration coefficient value for the maximum penetration depth was achieved. The obtained analytical solution was generalized on multi-reservoir strata with poor interlayer crosslinking. The efficiency of profile conformance improvement was described by the differences in the root-mean-square deviations of the inflow velocities in interlayers from mean values before and after the treatment. It was shown that the complex criterion of suspension treatment efficiency should include a reduction in total injectivity. An increase in suspension slug volume improves the injectivity profile but decreases the total injectivity of an injector.

Influence of Deformations on the Filtration Coefficient of Materials

This article is devoted to the study of the filtration coefficient depending on the loads applied to the material. In filtration theory, it is classical to solve problems with a constant filtration coefficient. Moreover, due to the conditionality of the filtration coefficient value by various physical and chemical processes, both in the solid fraction and in the liquid, its value is usually determined empirically. However, it is obvious that depending on the loads applied to the material, the pore space and filtration coefficient will change. This is especially true when using various filter materials, such as concrete. The latter, depending on the brand, can absorb the liquid quite well. Therefore, assuming that the pore space is a collection of capillary tubes, the paper shows the relationship between the filtration coefficient and the average pore diameter of the material. The dependence of the material filtration coefficient on the first invariant of the stress tensor arising in the medium is found. The change in the filtration coefficient of a concrete slab at different points is shown when a force load is applied to its upper surface.

Geo-Composite Drainage Material for Hydro-Technical and Civil Engineering

The article deals with the «GP» geo-composite drainage material, which is used in hydro-technical, civil, as well as environmental, industrial and landscape construction. This material is intended for complex application, as a separating, filtering and reinforcing layer in the structures of protective dams on rivers, reservoirs, channels, an earth work of linear transport constructions (automobile and railway facilities) and other hydraulic engineering constructions. It is a combined geo-synthetic material, including a rigid geo-grid of the lattice structure and a filtering geotextile element. As a result of the carried out researches, its basic physical and mechanical characteristics have been established: tensile strength, surface density of geotextile and the material, relative elongation at maximum load, filtration coefficient normal to the material level.

New Types of Geo-Composite Materials for Anti-Filtration Systems

The article discusses the results of studies of new types of geocomposite materials used for anti-filtration and drainage purposes in hydraulic engineering and environmental protection construction. As the main elements, the presented geocomposite materials include various types of synthetic materials – bentonite mats and profiled geomembrane. A distinctive feature of these materials is the inclusion of additional elements of geotextile material or polymer geomembrane in their design, these elements are connected to the main element by thermal bonding. As a result, the combined geocomposite materials acquire new properties: they become more waterproof and durable. At the same time, waterproof materials are used for anti-filtration systems (as screens and coverings for canals, ponds, dams and various types of waste collectors), and previous material are used for drainage systems (as drainage in hydraulic and civil engineering). New types of geocomposite materials have improved properties on water resistance and water permeability (filtration coefficient), durability and strength.

The peculiarities of pulmonary macro- and microhemodynamics changes after treatment with agonists and blockers of cholinoceptors

Background. The pulmonary arterial and venous vessels are innervated by parasympathetic cholinergic nerves. However, the studies, performed on the isolated rings of pulmonary vessels, can not give answer to the question about the role of cholinergic mechanisms in the changes of pulmonary circulation in full measure. Aim. The comparative analysis of the changes of the pulmonary macro- and microhemodynamics after acetylcholine, atropine, pentamine and nitroglycerine treatment. Materials and methods. The study was carried out on the anesthetized rabbits in the condition of intact circulation with the measurement of the pulmonary artery pressure and flow, venae cavae flows, cardiac output, and also on isolated perfused lungs in situ with stabilized pulmonary flow with measurement of the perfused pulmonary artery pressure, capillary hydrostatic pressure, capillary filtration coefficient and calculation of the pulmonary vascular resistance, pre- and postcapillary resistances. Results. In the conditions of intact circulation after acetylcholine, pentamine and nitroglycerine treatment the pulmonary artery pressure and flow decreased, the pulmonary vascular resistance did not change as a result of decreasing of pulmonary artery flow and left atrial pressure due to diminution of venous return and venae cavaе flows. On perfused isolated lungs acetylcholine caused the increasing of pulmonary artery pressure, capillary hydrostatic pressure, pulmonary vascular resistance, pre- and postcapillary resistance and capillary filtration coefficient. After M-blocker atropine treatment the indicated above parameters of pulmonary microcirculation increased, on the contrary, after N-blocker pentamine treatment they decreased. Nitroglycerine infusion caused less decreasing of the parameters of pulmonary microcirculation in comparison with effects of pentamine, but capillary filtration coefficient decreased to a greater extent. These data indicate that nitroglycerine decreases endothelial permeability of pulmonary microvessels. Conclusion. After activation or blockade of cholinergic mechanisms in the condition of intact circulation the calculated parameter of pulmonary vascular resistance is depended from the ratio of the pulmonary artery pressure and flow and left atrial pressure, which are determined by the venous return. The different character of the changes of pulmonary microcirculatory parameters after M-blocker atropine and N-blocker pentamine treatment is evidence of reciprocal relations of M- and N-cholinoceptors in the nervous regulation of the pulmonary microcirculatory bed.

Rheology and Dynamic Filtration of Foam Fracturing Fluid Enhanced by Cellulose Nanofibrils

Foam fracturing is an effective method for the development of unconventional reservoirs. However, due to lamellar film, high pressure differences within foam films, and the strong diffusivity of the internal phase, foam is prone to suffering from unstable phenomena such as rupture, drainage, disproportionation, etc., thus leading to uncontrollable foam flow behavior in the tube and formation. In this work, cellulose nanofibrils (CNFs) were used to enhance foam fracturing fluid. The target is not only to obtain a stable foam system, but also to control its rheology, proppant-carrying and leak-off behavior. The stability of the N2 foam fracturing fluid with CNFs was firstly explored via static tests by measuring its foam volume and liquid drainage. Then, the viscosity of foam fracturing fluids with different foam quality was measured using a tube viscometer under conditions of use, to evaluate the rheology of foam with CNFs. Subsequently, the proppant-carrying capacity was evaluated by observing suspension state of proppants in foam over time. The microscopic images of the foam with proppants were collected to analyze the interaction between bubbles and proppant. Finally, the dynamic filtration behavior and core damage of foam with CNFs were investigated by using a dynamic filtration apparatus. The results of the static tests showed that the stability of foam was significantly enhanced by the addition of CNFs, and the liquid drainage and gas diffusion could be effectively inhibited. Upon foam evolution, bare surfactant foam formed a polyhedral structure rapidly, while the CNFs enhanced foam maintained spherical and dense for a long time. The viscosity of foams with and without cellulose nanofibrils showed a shear thinning behavior. With the addition of CNFs, the viscosity of foam was improved by 3 - 6 times compared with bare surfactant foam and its value was increased with foam quality changing from 60% to 80%. The results of proppant-carrying tests indicated that the proppants suspension in foam was improved obviously as the cellulose nanofibrils were added. For CNFs-stabilized foam, the aqueous film of bubbles became thicker and the mechanical strength of foam structure was improved, thus enhancing the proppant suspension in the foams. Moreover, the filtration control performance of CNFs foam was also improved compared with bare surfactant foam. The filtration coefficient of CNFs foam fracturing fluid decreased with increasing CNFs concentration at a filtration pressure difference of 3 MPa, and core damage was maintained at a relatively low level. Additionally, the filtration coefficient of CNFs-stabilized foam and its core damage could be reduced with the increase of foam quality from 60% to 80%. The stability, rheology, proppant-carrying and dynamic filtration control of foam fracturing fluid enhanced by cellulose nanofibrils were explored in this work. The results show that the addition of CNFs effectively improves the stability of the foam, thus enabling the rheology, proppant-carrying and the dynamic filtration to be well controlled, which provides a high-performance and eco-friendly foam fracturing fluid.

EXPERIMENTAL SUBSTANTIATION OF SOIL SELECTION IN RECONSTRUCTION OF A MAIN GAS PIPELINE

The results of complex geotechnical studies aimed at creating a temporary soil dam for the reconstruction of the main gas pipeline are conducted. Based on the study of the properties of the three types of soils that are in the vicinity, the technical-economical efficiency and prediction of the compaction of the recommended soil are substantiated. The choice of soil laid in the dam should be carried out on the basis of the study of the properties of soils and feasibility study. Technical-economical assessment is impossible without knowledge of the characteristics of the soil, which were obtained in laboratory conditions. Three series of experiments were performed for this: determination of soil density; determination of the angle of repose; determination of soil filtration coefficient. The parameters were investigated in the course of the experiments, on which the quality of the soil dam depends to the greatest extent: density; angle of repose during dumping; filtration properties (filtration coefficient). Based on an analysis of the current situation, proceeding on environmental requirements and considerations of economic feasibility, it was proposed to fill in a temporary embankment to allow the piles to be loaded by driving, and to make it out of medium-sized sand composing the surface thickness in a given area. On the assumption of the technological requirements of the reconstruction, the dam should be 5 m high and 36 m high on the top and 51 m high on the bottom. Based on experimental-analytical researches, a motivated choice of soil is substantiated, which made it possible to obtain an economic effect confirmed by the act.

Abnormalities of the lymphatic system and impaired fluid clearance in patients with heart failure with preserved ejection fraction

Background Coronary and skeletal muscle microvascular dysfunction have been proposed as main factors in the pathogenesis of Heart Failure with Preserved Ejection Fraction (HFpEF). However, assessment of systemic arterial function has only been indirect thus far; most importantly, no direct link between systemic microvasculature and congestion, one of the core characteristics of the syndrome, has yet been investigated. Purpose To provide direct functional and anatomical characterisation of the systemic microvasculature and to explore in vivo parameters of capillary fluid extravasation and lymphatic clearance in HFpEF. Methods In 16 patients with HFpEF and 16 age- and sex-matched healthy controls (72±6 and 68±5 years, respectively) we determined peripheral microvascular filtration coefficient (proportional to vascular permeability and area) and isovolumetric pressure (above which lymphatic drainage cannot compensate for fluid extravasation) by venous occlusion plethysmography and collected a skin biopsy for vascular immunohistochemistry and gene expression analysis (TaqMan). Additionally, we measured brachial flow-mediated dilatation (FMD) and assessed by wire myography the vascular function of resistance arteries isolated from gluteal subcutaneous fat biopsies. Results Skin biopsies in patients with HFpEF showed rarefaction of small blood vessels (82±31 vs 112±21 vessels/mm2; p=0.003) and in ex-vivo analysis (n=6/group) we found defective relaxation of peripheral resistance arteries (p<0.001). Accordingly, post-ischaemic hyperaemic response (fold-change vs baseline, 4.6±1.6 vs 6.7±1.7; p=0.002) and FMD (3.9±2.1 vs 5.6±1.5%; p=0.014) were found to be reduced in patients with HFpEF compared to controls. In the skin of patients with HFpEF we also observed a reduced number (85±27 vs 130±60 vessels/mm2; p=0.012) but larger average diameter of lymphatic vessels (42±19 vs 26±9 μm2; p=0.007) compared to control subjects. These changes were paralleled by reduced expression of LYVE1 (p<0.05) and PROX1 (p<0.001), key determinants of lymphatic differentiation and function. Whilst patients with HFpEF had reduced peripheral capillary fluid extravasation compared to controls (microvascular filtration coefficient, leg 33.1±13.3 vs 48.4±15.2, p<0.01; trend for arm 49.9±20.5 vs 66.3±30.1, p=0.09), they had lower lymphatic clearance (isovolumetric pressure: leg 22±4 vs 16±4 mmHg, p<0.005; arm 25±5 vs 17±4 mmHg, p<0.001). Conclusions We provide direct evidence of systemic dysfunction and rarefaction of small blood vessels in patients with HFpEF. Despite a reduced microvascular filtration coefficient, which is in keeping with microvascular rarefaction, the clearance of extravasated fluid in HFpEF is limited by an anatomically and functionally defective lymphatic system. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): British Heart Foundation Centre of Research Excellence Award