Abstract The surface treatment by a powder coating is one of the progressive technologies. Such coatings are resistant to corrosion and mechanical wearing. The quality of surface protection is affected primarily by a layer pre-treatment, the type of surface tretment, the system selection and the method and quality of application. Taking into account all the surface pre-tretment methods, the chemical pre-modification is a leading method. One of the methods is pre-treatment using a conversion coating which was developed on the nanotechnology basis - BONDRITE NT. That non-phosphate chemical pre-treatment is utilized at a surrounding temperature. It creates nano-ceramic protective layer on steel, zinc and aluminium surfaces, and as the result the coating has a significant adhesion. In the paper, the possibilities for the improvement of corrosion resistance of powder coatings using the subject conversion coating are presented at the current pasivation of respective surface.
{"title":"Evaluation of corrosion resistance of powder coatings after various surface chemical pre-treatment","authors":"D. Draganovská, J. Brezinová","doi":"10.1515/kom-2017-0008","DOIUrl":"https://doi.org/10.1515/kom-2017-0008","url":null,"abstract":"Abstract The surface treatment by a powder coating is one of the progressive technologies. Such coatings are resistant to corrosion and mechanical wearing. The quality of surface protection is affected primarily by a layer pre-treatment, the type of surface tretment, the system selection and the method and quality of application. Taking into account all the surface pre-tretment methods, the chemical pre-modification is a leading method. One of the methods is pre-treatment using a conversion coating which was developed on the nanotechnology basis - BONDRITE NT. That non-phosphate chemical pre-treatment is utilized at a surrounding temperature. It creates nano-ceramic protective layer on steel, zinc and aluminium surfaces, and as the result the coating has a significant adhesion. In the paper, the possibilities for the improvement of corrosion resistance of powder coatings using the subject conversion coating are presented at the current pasivation of respective surface.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/kom-2017-0008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46562456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Pokorný, R. Pernicová, M. Vokáč, I. Sedlářová, M. Kouřil
Abstract The paper summarizes the impact of produced hydrogen and calcium hydroxyzincate (Ca[Zn(OH)3]2·2H2O) on the formation of the porous structure of cement paste in the vicinity of hot-dip galvanized steel. These substances result from cathodic (hydrogen) and anodic (zincates-formed by reaction with hydroxides) corrosion reactions of hot-dip galvanized steel (or pure zinc) in the cement paste. The cement binder pore structure was studied by means of mercury porosimetry and analysis of scanning electron microscopy and confocal microscopy images. The porosity of the cement paste at the galvanized steel / cement interphase increased as a result of galvanized steel corrosion while hydrogen was formed. Such a porous structure was maintained throughout the maturation of cement paste. Kinetics of galvanized steel corrosion related primarily to water transport through the binder. The formation of calcium zincate did not result in transition of galvanized steel from active to passive state corrosion.
{"title":"The impact of produced hydrogen gas and calcium zincate on changes of porous structure of cement paste in the vicinity of hot-dip galvanized steel","authors":"P. Pokorný, R. Pernicová, M. Vokáč, I. Sedlářová, M. Kouřil","doi":"10.1515/kom-2017-0012","DOIUrl":"https://doi.org/10.1515/kom-2017-0012","url":null,"abstract":"Abstract The paper summarizes the impact of produced hydrogen and calcium hydroxyzincate (Ca[Zn(OH)3]2·2H2O) on the formation of the porous structure of cement paste in the vicinity of hot-dip galvanized steel. These substances result from cathodic (hydrogen) and anodic (zincates-formed by reaction with hydroxides) corrosion reactions of hot-dip galvanized steel (or pure zinc) in the cement paste. The cement binder pore structure was studied by means of mercury porosimetry and analysis of scanning electron microscopy and confocal microscopy images. The porosity of the cement paste at the galvanized steel / cement interphase increased as a result of galvanized steel corrosion while hydrogen was formed. Such a porous structure was maintained throughout the maturation of cement paste. Kinetics of galvanized steel corrosion related primarily to water transport through the binder. The formation of calcium zincate did not result in transition of galvanized steel from active to passive state corrosion.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47486263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The objective of this work was to examine the properties of molybdate or tungstate based pigments whose surface has been coated with a conductive polymer, viz. either polyaniline phosphate (PANI) or polypyrrole phosphate (PPY), if used as pigments in organic coating materials. The anticorrosion pigments were prepared by high-temperature solid-state synthesis from the respective oxides, carbonates. The composite pigments (pigment/conductive polymer) were dispersed in a solvent-type epoxy-ester resin binder to obtain a series of paints whose anticorrosion properties were assessed by means of corrosion tests in accelerated corrosion test and by the linear polarisation method. Focus was on the anticorrosion properties of the paints depending on the pigment surface treatment, initial pigment composition, and pigment volume concentration (PVC) in the paint. The surface-treated pigment particles were expected to have a favourable effect on the anticorrosion and the mechanical properties of epoxy-ester resin based paints.
{"title":"The anticorrosion properties of pigments based on molybdates and tungstates surface-modified with conducting polymers","authors":"T. Hájková, A. Kalendová","doi":"10.1515/kom-2017-0001","DOIUrl":"https://doi.org/10.1515/kom-2017-0001","url":null,"abstract":"Abstract The objective of this work was to examine the properties of molybdate or tungstate based pigments whose surface has been coated with a conductive polymer, viz. either polyaniline phosphate (PANI) or polypyrrole phosphate (PPY), if used as pigments in organic coating materials. The anticorrosion pigments were prepared by high-temperature solid-state synthesis from the respective oxides, carbonates. The composite pigments (pigment/conductive polymer) were dispersed in a solvent-type epoxy-ester resin binder to obtain a series of paints whose anticorrosion properties were assessed by means of corrosion tests in accelerated corrosion test and by the linear polarisation method. Focus was on the anticorrosion properties of the paints depending on the pigment surface treatment, initial pigment composition, and pigment volume concentration (PVC) in the paint. The surface-treated pigment particles were expected to have a favourable effect on the anticorrosion and the mechanical properties of epoxy-ester resin based paints.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/kom-2017-0001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47843350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This work deals with the characterization of Ni–P coating prepared via electroless deposition on wrought AZ31magnesium alloy. For the application of electroless deposition was proposed and optimized a suitable pretreatment process of magnesium alloy surface followed by Ni–P coating in the nickel bath. The chemical composition of Ni–P based coating was characterized using the scanning electron microscope with chemical composition analysis. Next, physico-chemical properties and mechanical characteristics of Ni–P coating were evaluated. The mechanism of corrosion degradation of the coating and the substrate was also studied in this work.
{"title":"Characterization of Ni-P coating prepared via electroless deposition on AZ31 magnesium alloy","authors":"M. Buchtík, P. Kosár, J. Wasserbauer, P. Doležal","doi":"10.1515/kom-2016-0026","DOIUrl":"https://doi.org/10.1515/kom-2016-0026","url":null,"abstract":"Abstract This work deals with the characterization of Ni–P coating prepared via electroless deposition on wrought AZ31magnesium alloy. For the application of electroless deposition was proposed and optimized a suitable pretreatment process of magnesium alloy surface followed by Ni–P coating in the nickel bath. The chemical composition of Ni–P based coating was characterized using the scanning electron microscope with chemical composition analysis. Next, physico-chemical properties and mechanical characteristics of Ni–P coating were evaluated. The mechanism of corrosion degradation of the coating and the substrate was also studied in this work.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/kom-2016-0026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41315545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Increasing the functional parameters of coating composition-based protective coatings is a strongly emerging trend. However, there are some limits to the increasing of utility parameters of protective coatings – always where such parameters are opposite to the basic property, which is corrosion protection. The presented study describes a case of a premature failure in the corrosion protection secured by a duplex system that occurred after the paint system had been enriched with an anti-sliding property.
{"title":"A self-destroying mechanism generated when functional parameters of paint system layers are improved in a non-suitable manner","authors":"L. Mindos, M. Parakova","doi":"10.1515/kom-2017-0004","DOIUrl":"https://doi.org/10.1515/kom-2017-0004","url":null,"abstract":"Abstract Increasing the functional parameters of coating composition-based protective coatings is a strongly emerging trend. However, there are some limits to the increasing of utility parameters of protective coatings – always where such parameters are opposite to the basic property, which is corrosion protection. The presented study describes a case of a premature failure in the corrosion protection secured by a duplex system that occurred after the paint system had been enriched with an anti-sliding property.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44230467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The paper deals with evaluation the corrosion characteristics of welded joints in two corrosion environments – SARS and 0.1 M NaCl solution. Welds were made by MAG technology using three protective gas mixtures - Ferroline He20C8, Ferroline C18 and Ferroline C6X1. There were realised chemical analysis of the base material and weld metal of all welded joints, Vickers hardness test of the base material, heat affected zones and weld metals, metallographic analysis of all areas of welds and measurement of base and weld metal corrosion rate in two corrosion environments. Hardness increases from the base material through the HAZ to the weld metal. The maximum difference between the hardness of the weld metal and the base material is 36 HV 0.1 - realised welds do not show a notch effect. The corrosion rate of the materials in SARS solution was higher than in the NaCl solution. The corrosion rate in weld metals of all welded joints was lower than the corrosion rate of the base material. The lowest corrosion rate in both corrosive environments showed a weld metal made using shielding gas Ferroline C18.
{"title":"Determination corrosion rate of welded joints realised by MAG technology","authors":"A. Guzanová, J. Brezinová, J. Viňáš, J. Koncz","doi":"10.1515/kom-2017-0002","DOIUrl":"https://doi.org/10.1515/kom-2017-0002","url":null,"abstract":"Abstract The paper deals with evaluation the corrosion characteristics of welded joints in two corrosion environments – SARS and 0.1 M NaCl solution. Welds were made by MAG technology using three protective gas mixtures - Ferroline He20C8, Ferroline C18 and Ferroline C6X1. There were realised chemical analysis of the base material and weld metal of all welded joints, Vickers hardness test of the base material, heat affected zones and weld metals, metallographic analysis of all areas of welds and measurement of base and weld metal corrosion rate in two corrosion environments. Hardness increases from the base material through the HAZ to the weld metal. The maximum difference between the hardness of the weld metal and the base material is 36 HV 0.1 - realised welds do not show a notch effect. The corrosion rate of the materials in SARS solution was higher than in the NaCl solution. The corrosion rate in weld metals of all welded joints was lower than the corrosion rate of the base material. The lowest corrosion rate in both corrosive environments showed a weld metal made using shielding gas Ferroline C18.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46416413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Acrylate varnishes are due to their suitable properties frequently used in restoration and preservation on variety of historical objects and materials. Common practice of their application involves using as an adhesive agents, consolidants and protective coatings. The purpose of protective coatings especially on metal artefacts is to reduce access of pollutants to the surface of the artefact. In this paper, coatings prepared from two acrylate polymers Paraloid B72 and Paraloid B48N are compared in terms of permeability for water and level of protective properties against air pollutants. For this purpose, electrochemical impedance spectroscopy and resistometric method were chosen for analysis of the coatings. Obtained results show lower permeability for water in case of Paraloid B72. However, same coating provided lower protection against air pollutants than Paraloid B48N coating.
{"title":"Evaluation of protective properties of acrylate varnishes used for conservation of historical metal artefacts","authors":"J. Švadlena, J. Stoulil","doi":"10.1515/kom-2017-0003","DOIUrl":"https://doi.org/10.1515/kom-2017-0003","url":null,"abstract":"Abstract Acrylate varnishes are due to their suitable properties frequently used in restoration and preservation on variety of historical objects and materials. Common practice of their application involves using as an adhesive agents, consolidants and protective coatings. The purpose of protective coatings especially on metal artefacts is to reduce access of pollutants to the surface of the artefact. In this paper, coatings prepared from two acrylate polymers Paraloid B72 and Paraloid B48N are compared in terms of permeability for water and level of protective properties against air pollutants. For this purpose, electrochemical impedance spectroscopy and resistometric method were chosen for analysis of the coatings. Obtained results show lower permeability for water in case of Paraloid B72. However, same coating provided lower protection against air pollutants than Paraloid B48N coating.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/kom-2017-0003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48026340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Poláčková, J. Petrů, M. Janák, J. Berka, A. Krausová
Abstract Carbon Capture and Storage (CCS) technologies are a perspective solution to reduce the amount of CO2 emissions. One of promising methods is Ca-looping, which is based on carbonation and calcination reactions. During both of these processes, especially calcination, high temperatures (650-950°C) are required. This means high demands on the corrosion resistance of equipment materials. Therefore, we carried out a study to suggest materials with suitable properties for calciner construction, which have to be particularly heat resistant: stainless steels (AISI 304, AISI 316L and AISI 316Ti) and nickel alloys (Inconel 713, Inconel 738, Incoloy 800H). A special device simulating calciner environment was built for this purpose. Chosen materials were tested in temperature 900°C, atmospheric pressure and gaseous environment with composition that can be possible in a calciner. The surfaces of materials were evaluated to determine composition and properties of formed oxide layers. High temperature oxidation was observed on all tested materials and oxide exfoliation occurred on some of tested materials (304, 316L).
{"title":"Materials for use in calcium looping technology for CCS – corrosion processes in high-temperature CO2","authors":"J. Poláčková, J. Petrů, M. Janák, J. Berka, A. Krausová","doi":"10.1515/kom-2017-0017","DOIUrl":"https://doi.org/10.1515/kom-2017-0017","url":null,"abstract":"Abstract Carbon Capture and Storage (CCS) technologies are a perspective solution to reduce the amount of CO2 emissions. One of promising methods is Ca-looping, which is based on carbonation and calcination reactions. During both of these processes, especially calcination, high temperatures (650-950°C) are required. This means high demands on the corrosion resistance of equipment materials. Therefore, we carried out a study to suggest materials with suitable properties for calciner construction, which have to be particularly heat resistant: stainless steels (AISI 304, AISI 316L and AISI 316Ti) and nickel alloys (Inconel 713, Inconel 738, Incoloy 800H). A special device simulating calciner environment was built for this purpose. Chosen materials were tested in temperature 900°C, atmospheric pressure and gaseous environment with composition that can be possible in a calciner. The surfaces of materials were evaluated to determine composition and properties of formed oxide layers. High temperature oxidation was observed on all tested materials and oxide exfoliation occurred on some of tested materials (304, 316L).","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48146561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In the present study, we investigated the influence of hammer peening (HP) with tungsten carbide surface coating (WCSC) on high cycle bending fatigue performance of the carbon steel (CS) manufactured as specified in Bureau of Indian Standards BIS 2062 steel. Totally there are twenty-four numbers of specimens cast and tested to investigate fatigue performance. Constantly high cycle bending fatigue load (HBFL) were applied for all specimen, different range of bending stress applied to the specimen and the stress ratio maintained as R = 1. Investigation results show there is up to 40 percent of the fatigue life improvement possible by the surface treatments to the CS material. From the research to date the corrosion and pitting corrosion can be treated by modifying the surface layer of the metal by treating different peening methods and coating.
{"title":"Effect of hammer peening with tungsten coating on fatigue properties of carbon steel under rotating bending","authors":"S. Kanchidurai","doi":"10.1515/kom-2017-0018","DOIUrl":"https://doi.org/10.1515/kom-2017-0018","url":null,"abstract":"Abstract In the present study, we investigated the influence of hammer peening (HP) with tungsten carbide surface coating (WCSC) on high cycle bending fatigue performance of the carbon steel (CS) manufactured as specified in Bureau of Indian Standards BIS 2062 steel. Totally there are twenty-four numbers of specimens cast and tested to investigate fatigue performance. Constantly high cycle bending fatigue load (HBFL) were applied for all specimen, different range of bending stress applied to the specimen and the stress ratio maintained as R = 1. Investigation results show there is up to 40 percent of the fatigue life improvement possible by the surface treatments to the CS material. From the research to date the corrosion and pitting corrosion can be treated by modifying the surface layer of the metal by treating different peening methods and coating.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49277053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Novikova, M. Kouřil, Š. Msallamová, J. Stoulil, N. Strnadová
Abstract Concentrating of pore bentonite water as a result of water evaporation at the hot container surface is expected when the bentonite cover of the permanent nuclear waste container is being gradually saturated. The study assesses the influence of an extent of the pore water enrichment by chloride and sulphate ions up to a multiple of a hundred of their equilibrium concentration. An increase of concentration of these ions does not imply an increase of the electrolyte aggressivity automatically. A minimum of corrosion resistance was observed at triplicate concentration at all temperatures, 40, 70 and 90°C. Even more significant impact on corrosion behaviour was recognized for composition of anoxic atmosphere above the electrolyte. Contrary to nitrogen, the mixture of nitrogen and carbon dioxide remarkably elevates the electrolyte’s corrosion aggressivity.
{"title":"Corrosion behaviour of steel CSN 422707.9 in concentrated synthetic bentonite pore water","authors":"D. Novikova, M. Kouřil, Š. Msallamová, J. Stoulil, N. Strnadová","doi":"10.1515/kom-2016-0011","DOIUrl":"https://doi.org/10.1515/kom-2016-0011","url":null,"abstract":"Abstract Concentrating of pore bentonite water as a result of water evaporation at the hot container surface is expected when the bentonite cover of the permanent nuclear waste container is being gradually saturated. The study assesses the influence of an extent of the pore water enrichment by chloride and sulphate ions up to a multiple of a hundred of their equilibrium concentration. An increase of concentration of these ions does not imply an increase of the electrolyte aggressivity automatically. A minimum of corrosion resistance was observed at triplicate concentration at all temperatures, 40, 70 and 90°C. Even more significant impact on corrosion behaviour was recognized for composition of anoxic atmosphere above the electrolyte. Contrary to nitrogen, the mixture of nitrogen and carbon dioxide remarkably elevates the electrolyte’s corrosion aggressivity.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/kom-2016-0011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66981662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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