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A closed mathematical model of continuous spin detonation of a syngas—air mixture is stated in a three-dimensional unsteady gas-dynamic formulation, and an algorithm for numerically solving the problem is developed. The model is verified using experimental data on ignition delay at high temperatures and the results of one-dimensional numerical calculations of the Chapman–Jouguet detonation parameters. For three stoichiometric compositions in an annular cylindrical combustor 306 mm in diameter, single-wave continuous spin detonation modes are obtained and the three-dimensional structure and the main flow parameters are analyzed. The minimum possible flow rates for continuous detonation are obtained in the case of variable specific mixture flow rates in a range of kg/(s m 2 ). The resulting data are compared with existing experimental data

Methods proposed for mine water treatment use different advanced equipment such as aerators and circular settling tanks which ensure increase in pH and decrease in impurity concentrations by 10–50 times. Passive mine water treatment uses small cascade ponds, which enables additional purification of water due to deceleration in water flow velocity and because of the longer time of interaction between impurities and reagents. The reconstruction of the existing system of three treatment stages can reduce pollution of surface and ground water, which brings essential improvement of ecology and minimizes damage caused to the hydrosphere.

The Republic of Kalmykia is located in the northwestern part of the Caspian Region and belongs to arid regions. The issue of water resources availability is extremely relevant here. Groundwater plays an important role in this aspect as a main and often the only source of drinking water supply. However, its use is limited because of its low natural quality. An approach to an increase in the operational groundwater reserves is its artificial replenishment. The Russian Research Institute for Integrated Use and Protection of Water Resources in 2020–2021 studied the possibility of replenishing water resources of subsurface water bodies in the Republic of Kalmykia by the accumulation of surface water. The results of the studies suggested a conclusion that the artificial replenishment of groundwater in the territory of the Republic of Kalmykia is inexpedient, because even in years with the surface runoff volume with 50% exceedance probability, the volume of surface runoff will be not enough for freshening groundwater within a year to the standard level (TDS ≤1.0 g/dm 3 ). The formation of a permanent freshwater lens (the presence of which is of particular importance in dry years) in an aquifer within the system including infiltration basin and water well is impossible because its full drawdown will take place every year.

A mathematical model of continuous spin detonation for hydrogen-oxygen and hydrogen-air mixtures is developed within the framework of a nonstationary gas-dynamic formulation. An OpenFOAM package is used to carry out numerical calculations in an annular cylindrical combustor in order to compare the main solution parameters with experimental data for geometric dimensions of combustors 40 mm and 306 mm in diameter corresponding to the experiments for hydrogen-oxygen and hydrogen-air mixtures. Regimes with a single continuously rotating transversal detonation wave are obtained for given fuel mixtures. It is shown that the solution significantly depends on the coordinate along the radius. The results for the hydrogen-oxygen mixture are in good agreement with an experiment in terms of a wave velocity and satisfactory agreement relative to a front height and the number of waves (a 1.5- to 2-fold difference). The results for the hydrogen-air mixture are in satisfactory agreement with an experiment for the wave velocity and front height and significantly differ from it on a minimal flow rate of the mixture, in which the existence of continuous spin detonation is possible in the combustor.

The distribution of REE in groundwater of the catchments, which were formed during the long-term operation of copper mines in the Middle Urals (Russia), was studied. The groundwater composition reflects a significant removal of REE from water-bearing rocks, which leads to their enrichment by several orders of magnitude relative to the oceans, surface water and groundwater. Maximum REE values (up to 15 mg/L) were recorded in groundwater discharged to the surface in the collapse zone (pH=3.5). In mine shafts REE values do not exceed 0.3 mg/L. Water of mine wastes occupy an intermediate position: here REE content varies from 0.5 to 6.5 mg/L. The degree of REE fractionation in mine waters is lower than in oceanic, surface and underground waters of the active water exchange zone at much higher contents. The chemical composition of groundwater of the abandoned copper mine is determined by hypogene processes and structure of the mineralized supergene zone, its mineralogical composition, and oxidation-reduction conditions.

BackgroundIn this study, we analyzed incidences of VTE in patients with rheumatoid arthritis (RA) and osteoarthritis (OA) after total knee or hip arthroplasty, compared schemes of drug prevention and evaluated their efficiency.ObjectivesTo evaluate the efficiency of prevention of VTE in patients with rheumatoid arthritis and osteoarthritis after total knee replacement under comparable conditionsMethodsWe studied 151 patients operated in V.A. Nasonova Research Institute of Rheumatology for the period 2014–2015. Of these, 72 patients with RA (47.7%) and 79 patients with OA (52.3%). For a comparative analysis of the efficiency of anticoagulant therapy, each patient group was divided into 2 subgroups by type of drug therapy. The first - nadroparin calcium (the drug therapy was started for 12 hours after the operation at a dose of 0.1 ml per 10 kg of body weight one time per day), the second - nadroparin calcium with transfer to dabigatran etexilate (the first stage of 4 hours after the operation was started therapy by nadroparin calcium, and then after the removal of the epidural catheter moved to the dabigatran etexilate).Doppler ultrasonography (DUS) was routinely performed preoperatively and on postoperative day 7, 14, then 1 time a month for diagnosing a deep venous thrombosis (DVT). Time of observation was 6 months.ResultsVTE were reported in 6 (3.9%) patients, 1 of them (0.7%) with RA and 5 (3.3%) with OA. Distal deep vein thrombosis developed on 15 days after total knee replacement in RA patient. He received nadroparin calcium only. 4 patients with VTE after surgery from OA group used nadroparin calcium and 1 patient was on combined drug therapy. Of the 6 cases of VTE 4 (66.7%) were asymptomatic and 2 (33.3%) with development of clinical and laboratory picture. The case of thrombosis in a group of RA was asymptomatic. In a perioperative period of clinically significant bleeding was not seen.ConclusionsCases of VTE in patients with RA, despite the large number of risk factors, under comparable conditions is significantly lower than patients with OA. The number of asymptomatic deep vein thrombosis prevails over the development of clinical and laboratory complex of symptoms in both groups. In patients with RA and OA who were from the first group have reported 5 cases of VTE and only 1 case of VTE have reported in patients who were from second group. Combined drug VTE prevention in patients with RA and OA has been most effective and safe.Disclosure of InterestNone declared

Mining of volcanogenic copper pyrite deposits of the Middle Urals leads to the rock disintegration, their grinding, increasing the interaction surface. Sulfide minerals are oxidized by interaction with oxygen-enriched meteoric water and secondary minerals are formed (crystallo-hydrates of sulphates, hydroxides). Here technogenic zone hypergene (sulfuric acid weathering crust) is being formed. Once the water pumping activities are finished, the piezometric level recovers its position decreasing the unsaturated zone created during the mining activity, this increases the water-rock ratio increasing the amount of suppliers of sulphates, iron, non-ferrous metals and other elements to groundwater. It defines a low rate of rehabilitation of mining areas after the completion of mining and cessation of dewatering. The regularities of acidic water formation after filling the depression cone are investigated on the abandoned copper mines of the Middle Urals (Russia). The longevity of formation of extremely acidic and polluted waters is determined by the degree of saturation of the supergene zone with secondary minerals and the intensity of water exchange. Seasonal decrease in the component’s concentrations t in the period of winter and summer low water was recorded. The unstable character of groundwater components changes with a half-life of more than 5 thousand days is established. The duration of rehabilitation and restoration of groundwater quality will be at least a hundred years.

Mining and processing industry forms mining landscape. Reclamation of mined-out areas is an efficient way of the environment protection in mining regions. It is rational to make mining-disturbed lands suitable for further use by taking mineral mining and processing waste. Justification of technology of placing waste in the mined-out void of Vostochny open pit of Magnitogorsk Metallurgical Plant at Magnitnaya Mountain (Chelyabinsk Region) is based on the analysis of hydrodynamic and hydrochemical history of the project, laboratory studies into interaction of backfills with quarry water and prediction modeling of change of conditions in the course of backfilling the open pit by means of modeling hydrogeomigration.

Background Deep vein thrombosis (DVT) of the lower limbs during operations knee and hip arthroplasty in patients with rheumatic diseases are observed in 7-27% cases. Objectives To evaluate the efficiency of prevention of DVT in patients with rheumatic diseases and osteoarthritis under comparable conditions. Methods We have analyzed 304 patients operated in for the period 2012-2013. Of these, 188 - with rheumatic diseases, 116 patients - with osteoarthritis. A distinctive feature of the patients with rheumatic diseases was the presence of concomitant drug therapy for the underlying disease. Thus, 176 (94%) of patients with rheumatic diseases received NSAIDs, 168 (89%) of patients received disease-modifying antirheumatic drugs (DMARDs), 81 (43%) of patients received glucocorticosteroids, 45 (24) % of patients received biologic DMARDs. These drugs indirectly affect the hemostatic system, increase the effect of each other and inhibit platelet hemostasis. In the preoperative period the incidence of DUS-confirmed DVT was in 12 patients (6.4%) with rheumatic diseases, most of which consisted of patients with systemic lupus erythematosus (SLE) and SLE + anti-phospholipid syndrome (APS) - 7 patients (3,7%) and the incidence of DUS-confirmed DVT was in 15 patients (12.9%). It was old thrombosis usually under vessel recanalization. Patients with post-thrombotic venous disease of the lower extremities for 7 days prior to surgery taken nadroparin or fondaparinux sodium, on the 2nd day after surgery patients was transferred to oral anticoagulants. Another patients (292) with rheumatic diseases and osteoarthritis without DVT in anamnesis received oral anticoagulants – a direct thrombin inhibitor - Dabigatran etexilate (174 patients) and rivaroxaban (118 patients). The first intake of dabigatran etexilate (110mg) or rivaroxaban (10mg) was performed on the first day after the surgery. Later the patients were taking 220 mg (2 capsules) of dabigatran etexilate once per day or 10 mg of rivaroxaban once per day for 28-35 days. Doppler ultrasonography (DUS) was routinely performed preoperatively and on postoperative day 3, 7, 14, then 1 time a month for diagnosing a deep venous thrombosis (DVT). Time of observation was 3 months. Results None of the patients with rheumatic diseases after knee or hip replacement in the early postoperative period deep vein thrombosis of the lower limbs were found. In the control group of patients with osteoarthritis in the early postoperative period identified 8 cases (6.9%) deep vein thrombosis of the lower limbs. The causes of thrombosis were unjustified self- removal of the drug for 15-20 days after surgery (6 cases), and later appointment of the anticoagulant (2 cases). In the perioperative period of clinically significant bleeding was not seen. Conclusions Application of the above prevention of deep vein thrombosis of the lower limbs has been effective and convenient in the early postoperative period in patients with rheumatic diseases in replacement of hip or knee joints, but requires further study in patients with osteoarthritis. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.4909

The closure of mining facilities, especially those with a long history of mining, often results in degradation of the environment. In particular, the development of mineral deposits is accompanied by drainage interventions, restructuring and rebalancing of surface and groundwater flows, and changes in the qualitative composition of the hydrosphere. Cave mining operations involve geomechanical processes that provoke surface subsidence and displacement accompanied by earth surface disturbance. The cessation of mining means stoppage of drainage, which leads to the gradual filling of the cone of depression, formation of flooded areas, and mine water discharges at the surface. Unstable rock in the walls of water-filled open pits can lead to potentially dangerous landslides. Given the fact that residential and industrial areas were often historically constructed close to the mines (sometimes within the mining allotment), the hydro-environmental problems of old industrial districts become particularly acute post-mining. Also, in many cases, it is difficult to determine which factors, natural (geological structure, geomorphological conditions, water content of the period) or human-induced (cessation of pumping), are responsible for area flooding, especially where these sites are located a considerable distance from the closed mine. This gives rise to speculations and irrational technical solutions. Using the Chelyabinsk Coal Basin as an example, we consider the eco-hydrogeological issues that arose after the completion of mining operations and cessation of drainage, and we propose measures to reduce their negative impact on the area’s hydro-geoecological conditions.