Russian Journal of Non-Ferrous Metals最新文献

{"title":"Deforming devices with a power drive made of a shape memory material Design solutions, calculation and design procedure","authors":"V. Alekhina, V. Glushchenkov, F. Grechnikov","doi":"10.17073/0021-3438-2022-5-26-35","DOIUrl":"https://doi.org/10.17073/0021-3438-2022-5-26-35","url":null,"abstract":"The article presents engineering solutions developed to create deforming devices with a power drive made of a shape memory material. As an example, the paper considers designs of a press, a stamp press made using new designs of multi-link power drives. A method is proposed for engineering a universal multi-link power drive with power elements made of a thermally thin shape memory material. The paper provides the analysis of thermal processes in power elements of various shapes, geometric dimensions and using different methods of their heating (current transmission heating, convective and radiant heat exchange) to determine the efficiency of the engineered devices. Processing and operational properties of thermally thin power elements of a multi-link power drive are investigated. To determine their qualitative and quantitative indicators, a measuring bench was created with such functions as recording the amperage, temperature change, displacement, and developed forces on a single time scale. A relationship between the heating rate, rate of operating force development and return deformation force was found. A line of universal power drives with a developed deformation force of 500–10000 N and a displacement of 1.0–8.0 mm was created based on the calculations performed with the results of their testing and use in existing models of deforming devices presented.","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"21 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87334393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hereditary Influence of Deformed Waste on the Efficiency of Modification of Alloy Systems Al–Si–Mg and Al–Mg","authors":"K. V. Nikitin,&nbsp;V. I. Nikitin,&nbsp;I. Yu. Timoshkin,&nbsp;R. M. Biktimirov,&nbsp;A. P. Novikov","doi":"10.3103/S1067821222040113","DOIUrl":"10.3103/S1067821222040113","url":null,"abstract":"<p>The results of studies on the effect of the charge composition on the structure and mechanical properties of cast aluminum alloys of the Al–Si–Mg (AK9ch) and Al–Mg (AMg6l) systems are presented. It is shown that the contribution of deformed waste in the composition of the charge (electrical waste of aluminum and waste of beverage cans based on alloy 3104—for AK9ch; alloy plates AMg6—for AMg6l) contributes to the formation of dispersed micro- and macrostructure of working alloys in the solid state. The effect of modification (AlSr20 master alloy—for AK9ch; AlTi5 master alloy—for AMg6l) on the structure and mechanical properties of alloys obtained by various charge variants is investigated. Experiments on the effect of the charge composition on the modifiability of AK9ch and AMg6l alloys have shown that the structure of the deformed waste is partially inherited by working alloys through the liquid state. With similar chemical compositions, smaller micro- and macrostructure sizes and increased mechanical properties (tensile strength and elongation under tension) are characteristic of alloys obtained using an increased proportion of deformed waste in the composition of the charge. It was found that, in alloys with an increased proportion of deformed waste, exceeding a certain amount of the modifier element (0.06% Sr for the AK9h alloy; 0.04% Ti for the AMg6l alloy) causes the manifestation of the effect of overmodification. This is expressed in the enlargement of the parameters of the micro- and macrostructure, as well as a decrease in the tensile strength. The results obtained show that the optimal amount of the proportion of deformed waste in the composition of the charge will make it possible in practice to reduce the consumption of expensive modifying ligatures with a guaranteed effect of modification.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 4","pages":"400 - 408"},"PeriodicalIF":0.8,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4642144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structure and Properties of Al–Cu–Yb Alloy with Iron and Silicon Impurities","authors":"M. V. Barkov,&nbsp;O. I. Mamzurina,&nbsp;M. V. Glavatskikh,&nbsp;R. Yu. Barkov,&nbsp;A. V. Pozdniakov","doi":"10.3103/S1067821222040034","DOIUrl":"10.3103/S1067821222040034","url":null,"abstract":"<p>The effect of iron and silicon impurities on the phase composition and properties of the Al–4.3Cu–2.2Yb quasi-binary alloy has been determined. In the microstructure of the cast alloy, in addition to the aluminum solid solution and dispersed eutectic ((Al) + Al₈Cu₄Yb), in which about 1% of iron is dissolved, the Al₃Yb/(Al,Cu)₁₇Yb₂ and Al₈₀Yb₅Cu₆Si₈ phases are identified, which are not found in an alloy of a similar composition without impurities. After homogenization annealing at a temperature of 590°C for 3 h, the structure is represented by compact fragmented and coagulated intermetallic compounds 1–2 μm in size and a solid solution (Al) with a maximum copper content of 2.1%. The hardness of the deformed sheets significantly decreases after 0.5 h and changes slightly up to 6 h of annealing at temperatures of 150–210°C. After annealing at 180°C for 3 h, a substructure with a subgrain size of 200–400 nm is formed in the alloy structure. The softening after annealing of the rolled sheets at temperatures up to 250°C occurs owing to the recovery and polygonization processes and above 300°C owing to recrystallization. After annealing for 1 h at 300°C, the recrystallized grain size is 7 μm. The grain size increases to 16 µm after annealing for 1 h at 550°C. The Al–4.3Cu–2.2Yb alloy with impurities has a conditional yield strength of 205–273 MPa, a tensile strength of 215–302 MPa, and a relative elongation of 2.3–5.6% in the rolled alloy after annealing. Iron and silicon impurities do not lead to the formation of coarse lamellar intermetallic phases and do not reduce the ductility of the investigated alloy.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 4","pages":"434 - 440"},"PeriodicalIF":0.8,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4322325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Visible Light Photocatalytic Activity of Ag2S/Ag Nanocomposite Precipitated from Silver Thiosulfate Complex through Ultraviolet Photolysis","authors":"Chao Han,&nbsp;Jialong Cao,&nbsp;Chu Cheng,&nbsp;Panpan Xu,&nbsp;Guangxin Wang,&nbsp;Jiwen Li","doi":"10.3103/S1067821222040046","DOIUrl":"10.3103/S1067821222040046","url":null,"abstract":"<p>The thiosulfate system for silver extraction has numerous characteristics such as high efficiency, low consumption, and environmental protection, and it has good application prospects. However, the high cost of metal recovery in thiosulfate systems limits its industrial application. A previous study indicated that Ag₂S/Ag nanocomposite clouds were precipitated from silver thiosulfate complex (AgTS) through ultraviolet photolysis, whereas the semiconductor-metal nanopowders synthesized through the hydrothermal synthesis process are usually important composites that can be used in photocatalysis, broad-spectrum antibacterial, and other environmental fields. Therefore, this study aims to develop high-value utilization of AgTS hydrometallurgical systems based on the photocatalytic properties of nanocomposites, and proposes research on the visible-light photocatalytic activity of Ag₂S/Ag photocatalytic systems precipitated from AgTS through ultraviolet photolysis. First, the morphology and optical properties of the Ag₂S/Ag nanocomposite were investigated. Next, the visible light photocatalytic activity of the Ag₂S/Ag nanocomposite was evaluated, and finally, the new high-value utilization research method of “ultraviolet absorption → ultraviolet photolysis → photocatalysis” was proposed. In this study, we demonstrate a novel method of high-value utilization of silver thiosulfate lixivium with a high photocatalytic efficiency of the Ag₂S/Ag nanocomposite of up to 47.98% after three cycles.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 4","pages":"369 - 378"},"PeriodicalIF":0.8,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4325066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rational Technology for Separation of Rare-Earth Elements of the Yttrium Group","authors":"A. V. Valkov,&nbsp;V. I. Petrov","doi":"10.3103/S1067821222040125","DOIUrl":"10.3103/S1067821222040125","url":null,"abstract":"<p>The features of the extraction technology for the separation of rare-earth elements (REEs) of the yttrium group are considered with regard to the sharp reduction in the price of individual oxides. The price reduction has the same nature as the low prices of lanthanum and cerium oxides and is associated with a predominant increase in the consumption of praseodymium and neodymium and a slow increase in the consumption of other REEs, with the exception of terbium and dysprosium. Since all REEs are extracted from rare-earth concentrates, less in demand ones are stored or sold at very low prices. Elements such as samarium, europium, gadolinium, and dysprosium are used in high-tech instruments and devices. In this case, it is possible to allow the operation of low-profit production, but technological solutions must certainly be built taking into account the minimum costs and be the most economically effective. The authors propose a technology for separating elements of the yttrium group including the stages of isolation of yttrium in a single-stage mode by extraction with a mixture of three extractants (25 vol % trialkylmethylammonium nitrate–20 vol % tributyl phosphate–20 vol % higher isomeric carboxylic acid), followed by separation of the triad of elements samarium–europium–gadolinium by extraction with organophosphoric acids (30 vol % solution of di-2-ethylhexylphosphoric acid or 30 vol % solution of bis(2,4,4-trimethylpentyl)-phosphinic acid). In the last operation, concentrates of the yttrium group REEs are isolated simultaneously. The process is carried out in the mode of complete internal irrigation using a 30 vol % solution of bis(2,4,4-trimethylpentyl)-phosphinic acid as an extractant. First, all cells of the cascade are filled with the initial solution. Separation zones are formed in the cells of the cascade with the accumulation of terbium–dysprosium, holmium–erbium, and thulium–ytterbium–lutetium concentrates. After the accumulation of products, the solution of concentrates is drained from the cells and the process starts again. If there is a need for any element of the yttrium group, the corresponding binary or ternary concentrate is separated to isolate the required element.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 4","pages":"385 - 391"},"PeriodicalIF":0.8,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4320840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Parameters of Melt Processing by Nanosecond Electromagnetic Pulses on the Structure Formation of Cast Aluminum Matrix Composites","authors":"V. B. Deev,&nbsp;E. Kh. Ri,&nbsp;E. S. Prusov,&nbsp;M. A. Ermakov,&nbsp;E. D. Kim","doi":"10.3103/S1067821222040058","DOIUrl":"10.3103/S1067821222040058","url":null,"abstract":"<p>The work is aimed at establishing the effect of nanosecond electromagnetic pulses (NEPs) with different amplitudes on the formation of the structure of cast aluminum matrix composites of the pseudo-binary Al–Mg₂Si system with hypoeutectic (5 wt % Mg₂Si) and hypereutectic (15 wt % Mg₂Si) composition. With an increase in the amplitude of the generator of NEPs in alloys with 5 and 15 wt % Mg₂Si, the structural components of the matrix alloy (α-solid solution and eutectic) are refined, while no significant differences in the sizes and morphology of primary crystals of Mg₂Si in the hypereutectic range of compositions were observed in the entire range of tested variants of the amplitude of the generator of NEPs. Presumably, the observed nature of the influence of NEPs on the structure of composites in the hypereutectic region of compositions is associated with the features of their crystallization behavior. The temperature range of the existence of the two-phase region L + Mg₂Si is much lower than the temperatures of irradiation with NEPs; apparently, in connection with this, NEPs do not affect the thermodynamic state of the interfaces “primary crystal Mg₂Si–melt.” It has been shown that a promising option for the simultaneous modifying effect on all structural components of Al–Mg₂Si aluminum matrix composites (solid solution, eutectic, primary Mg₂Si particles) is a combination of thermal-rate treatment and irradiation of melts with NEPs, as well as additional processing of melts by NEPs during solidification.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 4","pages":"392 - 399"},"PeriodicalIF":0.8,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4322324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrometallurgical Processing of Spent Zinc-Manganese Batteries","authors":"E. B. Kolmachikhina,&nbsp;K. D. Naumov,&nbsp;D. I. Bludova,&nbsp;S. A. Sap’yanov,&nbsp;V. G. Lobanov,&nbsp;Z. M. Golibzoda","doi":"10.3103/S1067821222040095","DOIUrl":"10.3103/S1067821222040095","url":null,"abstract":"<p>In this paper, the possibility of processing zinc-manganese batteries in alkaline solutions is studied. It is shown that three-stage washing can remove potassium chloride from the active mass of milled batteries. The regularities of influence of some parameters (temperature, amount of alkali and number of cycles) on the extraction of zinc into solution during alkaline leaching of a mixture of salt and alkaline batteries are established. The reason for the low extraction of zinc from this material is the presence of zinc and manganese compounds as heterolite and hydroheterolite that are difficult to dissolve in alkalis. It is found that, with an increase in the concentration of NaOH from 100 to 205 g/dm³, zinc extraction increases by 2.6 times, but a further increase in the concentration of NaOH, as well as an increase in temperature in the range of 30–85°C, does not affect the zinc extraction into solution. The optimal process parameters of leaching of salt and alkaline batteries at duration of 30 min and pulp density of 200 g/dm³ are determined as follows: temperature of 30°C, NaOH concentration of 390 g/dm³. Conducting experiments on the accumulation of zinc ions with repeated filtrate coursing for leaching shows that, upon increasing the concentration of alkali to 390 g/dm³, owing to cyclic treatment of solutions, it is possible to transfer the maximum possible amount of zinc into the solution without increasing the NaOH consumption. The zinc concentration in solutions after leaching was equal to 59 g/dm³, and the NaOH concentration was 300 g/dm³. The obtained solutions can be directed to zinc electrowinning and after that be returned for leaching.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 4","pages":"361 - 368"},"PeriodicalIF":0.8,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4325296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Novel Fabrication Approach for Ceramic Tiles from Red Mud and Steel Slag","authors":"Haitao Liu,&nbsp;Hengyao Dang,&nbsp;Wei Wang","doi":"10.3103/S1067821222040083","DOIUrl":"10.3103/S1067821222040083","url":null,"abstract":"<p>In order to investigate the structure and performance of specific ceramic materials, red mud, steel slag, and talc, which are commonly used as ceramic building materials, were fabricated by molding. The influences of particle size and composition on the properties of the ceramic materials were studied by differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. The results indicate that the main crystalline phases were diopside and anorthite. The ceramics possessed the best mechanical properties when sintered at about 1170°C, the particle size of the raw material powders was less than 74 μm, and the ceramic composition comprised 60–70% red mud, 20–30% steel slag, and 10% talc. The results of this work are useful for recycling of steel slag and red mud on a large scale.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 4","pages":"441 - 447"},"PeriodicalIF":0.8,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4322321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of High-Energy Ball Milling on the Microstructure, Phase Composition, and Microhardness of the Al–Mn–Cu Alloy","authors":"O. A. Yakovtseva,&nbsp;A. S. Prosviryakov,&nbsp;V. V. Cheverikin,&nbsp;E. N. Zanaeva,&nbsp;A. V. Mikhaylovskaya","doi":"10.3103/S1067821222040137","DOIUrl":"10.3103/S1067821222040137","url":null,"abstract":"<p>The influence of the treatment time in a planetary ball mill on the morphology, phase composition, and microstructure of the Al–Mn–Cu-based alloy and the same alloy with nanodiamond particles is studied by X-ray diffraction and scanning electron microscopy. The phase composition of the alloy is determined by X-ray diffraction after casting and milling for 5–20 h. It is shown that nanodiamond particles contribute to the coarsening of granules. The effect was intensified with an increase in the milling time to 20 h. The granular size weakly depends on the processing time for the initial alloy. The Cu-bearing phases of solidification origin are dissolved during milling. The lattice parameter of the aluminum solid solution decreases after five hours of treatment to 0.4028–0.4030 nm, and it increases with further increase in milling time. Exothermic peaks associated with the precipitation of secondary phases are revealed for mechanically alloyed granules during heating. An increase in the milling time reduces the intensity of peaks. The solidus temperature of the alloys decreases after mechanical alloying. For the nanodiamond-bearing sample, a high-temperature exothermic effect, which can be associated to the formation of aluminum carbides or oxidation reactions in nanodiamond particles, is observed. The maximum microhardness is achieved after 5–10 h of milling, and the nanodiamond particles slightly increase the maximum microhardness from 316 to 330 HV. The results indicate the dissolution of copper and manganese in the aluminum solid solution during milling for 5 h and their precipitation with increasing milling time. Nanodiamond particles do not influence the dissolution of elements but accelerate the solid solution decomposition with increasing milling time.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 4","pages":"426 - 433"},"PeriodicalIF":0.8,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4325062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of Temperature-Deformation Conditions for Rolling Aluminum Alloy Al–Mg–Sc Based on FEM Modeling","authors":"Yu. V. Gamin,&nbsp;S. P. Galkin,&nbsp;X. D. Nguyen,&nbsp;T. K. Akopyan","doi":"10.3103/S1067821222040071","DOIUrl":"10.3103/S1067821222040071","url":null,"abstract":"<p>The article discusses the features of radial shear rolling (RSR) of the aluminum alloy Al–Mg–Sc. The modeling of the RSR process by the finite element method in the QForm 3D program with variation of the elongation ratio per pass and the rolling speed has been implemented. On the basis of the results obtained, a study of the temperature field of the rod in the deformation zone has been carried out taking into account the cyclic deformation and the configuration of the flow trajectories. It is found that changes in the temperature field of the rod in the deformation zone are determined by the difference in the trajectory flow of the metal in the surface layers and in the axial zone. When the elongation ratio is varied from 1.6 to 2.4, heating occurs inconsistently from the center to the surface. The largest increase occurs for an area that is approximately 0.3<i>R</i> from the surface. For the axial zone, the temperature change in the deformation zone occurs smoothly and with an insignificant temperature difference of 5–10°C. The temperature on the surface of the rod has the greatest temperature fluctuations, which are explained by deformation heating and simultaneous contact with a cold roll during each deformation cycle. With a decrease in the rolling speed, a picture of the distribution of the temperature field of the rod in the deformation zone is observed, when the temperature of the central layers exceeds the surface temperature. Because of the long contact time of the rod with the roll, the surface temperature fluctuates up to 40–50°C with each deformation cycle. With an increase in the rolling speed, the amplitude of temperature fluctuations on the surface decreases, and the deformation heating increases. The obtained data on the relationship of controlled technological parameters with a change in the temperature field of the rod can be useful in the design of technological modes of rolling.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 4","pages":"417 - 425"},"PeriodicalIF":0.8,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4642145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}