Materials Science-Poland最新文献

{"title":"Comparative analysis of microstructure and selected properties of WC-Co-Cr coatings sprayed by high-velocity oxy fuel on S235 and AZ31 substrates","authors":"Ewa Jonda, Hanna Myalska-Głowacka, Leszek Łatka, Krzysztof Szymański, Magłorzata Dziekońska","doi":"10.2478/msp-2024-0002","DOIUrl":"https://doi.org/10.2478/msp-2024-0002","url":null,"abstract":"The purpose of this work was to carry out comparative studies of WC-Co-Cr coatings deposited using the high velocity oxy fuel (HVOF) method onto two types of substrate material: structural steel S235 and magnesium alloy AZ31. The influence of the substrate material type on the microstructure, phase composition, crystallite size, porosity, Vickers microhardness, instrumental hardness (H<jats:sub>IT</jats:sub>), Young’s modulus (E<jats:sub>IT</jats:sub>), and fracture toughness was investigated. For both substrates, the deposited coatings deposited were characterized with fine-grained and compact microstructure. The X-ray diffraction (XRD) revealed presence of following phases: WC, W<jats:sub>2</jats:sub>C, Co<jats:sub>0.9</jats:sub>W<jats:sub>0.1</jats:sub>, and Co<jats:sub>3</jats:sub>W<jats:sub>9</jats:sub>C<jats:sub>4</jats:sub>. The WC phase was the most desirable and stable one with crystallites were below 100 nm. On the other hand, the size of the W<jats:sub>2</jats:sub>C crystallites was below 30 nm. The coatings obtained showed porosity values equal to 2.3 ± 0.4 vol% and 2.8 ± 0.7 vol% for AZ31 and S235, respectively. The average Vickers microhardness for both types of sample was appproximately 1200 HV0.3. The average H<jats:sub>IT</jats:sub> values for carbide particles and metallic matrix were around 29 GPa and 6.5 GPa, respectively. In the case of E<jats:sub>IT</jats:sub>, it was around 620 GPa and 190 GPa for WC and Co-Cr, respectively. The differences between coatings were negligible. The E<jats:sub>IT</jats:sub> value for both coatings was equal to 344 ± 11 GPa. The fracture toughness was around 4.5 MPa · m<jats:sup>1/2</jats:sup> in both cases. The investigations revealed that it is possible to replace steel substrate material with a much lighter equivalent, in this case AZ31 alloy, without deterioration of the coating properties.","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"25 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140939270","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":"Enhanced catalytic activity of zeolitic imidazolate frameworks (ZIF-8) polyelectrolyte complex composites membranes by laser etching","authors":"Ting Yu, Boonyarach Kitiyanan, Stephan Thierry Dubas","doi":"10.2478/msp-2024-0004","DOIUrl":"https://doi.org/10.2478/msp-2024-0004","url":null,"abstract":"The effect of laser etching on the surface properties of composite polyelectrolyte complex (PEC) based membranes as mixed matrix membranes was studied. The PECs were prepared by the stoichiometric mixing of cationic PDDA (poly(diallyl dimethyl ammonium chloride)) and anionic PSS (poly(sodium 4-styrene sulfonate)) as polyelectrolytes with various contents of ZIF-8 as filler. Composite membranes usually display improved bulk properties depending on the nature of the filler, but the surface properties are often dictated by the matrix covering the surface. The PEC composite membranes were then subjected to laser etching, resulting in the enhanced exposure of embedded ZIF-8 particles within the PEC structure in an attempt to improve the surface properties of the composite membrane. The crystal structure, morphology, and distribution of zinc at the PECs surface, before and after laser etching, were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS), respectively. In order to evaluate the improvement of the surface properties of the laser-etched membranes, a model experiment involving a catalytic reaction was chosen. The pristine and laser treated surfaces were tested for their catalytic activity for the transesterification of triglycerides present in soybean oil with methanol at a temperature of 150°C. Interestingly, the laser-etched PECs displayed substantially enhanced activity compared to the original composite PEC membranes as a result of surface erosion. These results could be interesting for the future development of composite membranes with improved surface properties where the filler needs to expose the surface of the membranes.","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"48 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140939520","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":"Water absorption and mechanical behaviour of green fibres and particles acting as reinforced hybrid composite materials","authors":"Mohamed Kchaou, Sujin Jose Arul, A. Athijayamani, Priyabrata Adhikary, S. Murugan, Faisal Khaled Aldawood, Hussain F. Abualkhair","doi":"10.2478/msp-2023-0051","DOIUrl":"https://doi.org/10.2478/msp-2023-0051","url":null,"abstract":"This paper highlights the results of an experimental study on the preparation and characterization of <jats:italic>Luffa cylindrica</jats:italic> fiber (LCF) and groundnut shell particle (GSP) reinforced phenol-formaldehyde (PF) hybrid composites. The amount of LCFs was fixed at 25 wt%, while the amount of groundnut shell particles ranged from 0 to 25 wt%. Observations were made regarding the water absorption and thickness swelling behaviour of prepared hybrid composites. In addition, the mechanical behaviours of hybrid composites have been studied under both dry and wet conditions. In comparison to dry conditions, the mechanical properties of the hybrid composites were lower when they were wet. Hybrid composites comprising 25% <jats:italic>Luffa cylindica</jats:italic> fibre and 15% groundnut shell particle (25LCF/15GSP) exhibit the highest level of mechanical properties under both conditions. The percentages of water absorption and thickness swelling increase as groundnut shell particles increase. The composite 25LCF/25GSP exhibited the highest percentage of water absorption and thickness swelling. Compared to date palm leaf (DPL)-reinforced composites, 25LCF/15GSP showed more significant mechanical and physical properties. We concluded that the inclusion of groundnut shell particles in LCF/PF composites substantially improved the mechanical properties of the hybrid composite. The range of increment, however, was narrower under moist conditions compared to dry conditions.","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"20 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140598062","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":"Performance of green high-strength concrete incorporating palm oil fuel ash in harsh environments","authors":"Abdullah M. Zeyad, Megat Azmi Megat Johari, Ali Aliakbar, Hassan M. Magbool, Taksiah A. Majid, Majed A. A. Aldahdooh","doi":"10.2478/msp-2023-0042","DOIUrl":"https://doi.org/10.2478/msp-2023-0042","url":null,"abstract":"The corrosion of steel reinforcement by chloride is commonly recognized as a key factor that contributes to the degradation of durability in reinforced concreae structures. Using supplementary cementitious materials, such as industrial and agricultural waste materials, usually enhances the impermeability of the concrete and its corrosion resistance, acid resistance, and sulfate resistance. This study’s primary purpose is to examine the effects of replacing ordinary Portland cement (OPC) with ultrafine palm oil fuel ash (U-POFA) on the corrosion resistant performance of high-strength green concrete (HSGC). There were four HSGC mixes tested; the first mix contained 100% OPC, while the other mixes replaced OPC mass with 20%, 40%, and 60% of U-POFA. The performance of all HSGC mixes containing U-POFA on workability, compressive strength, porosity, water absorption, impressed voltage test, and mass loss was investigated at 7, 28, 60, and 90 days. Adding U-POFA to mixes enhances their workability, compressive strength (CS), water absorption, and porosity in comparison with mixes that contain 100% OPC. The findings clearly portrayed that the utilization of U-POFA as a partial alternative for OPC significantly enhances the corrosion-resistant performance of the HSGC. In general, it is strongly advised that a high proportion of U-POFA be incorporated, totaling 60% of the OPC content. This recommendation is the result of its significance as an environmentally friendly and cost-effective green pozzolanic material. Hence, it could contribute to the superior durability performance of concrete structures, particularly in aggressive environmental exposures. Highlights <jats:list list-type=\"bullet\"> <jats:list-item> The corrosion resistance performance of high-strength green concrete was investigated. </jats:list-item> <jats:list-item> Ultrafine palm oil fuel ash as a partial alternative of cement mass with 20%, 40%, and 60% was used. </jats:list-item> <jats:list-item> HSGC performance was evaluated in terms of workability, compressive strength, water absorption, porosity, impact stress testing, and mass loss. </jats:list-item> </jats:list>","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"51 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140598459","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":"Effects of B content on wear and corrosion resistance of laser-cladded Co-based alloy coatings","authors":"Rong Xia, Kun Zhang, Fengyuan Shu, Xin Zhang, Liying Yan, Cheng Li","doi":"10.2478/msp-2023-0040","DOIUrl":"https://doi.org/10.2478/msp-2023-0040","url":null,"abstract":"To improve the surface properties of Ti alloy, (Co<jats:sub>34</jats:sub>Fe<jats:sub>8</jats:sub>Cr<jats:sub>29</jats:sub>Ni<jats:sub>8</jats:sub>Si<jats:sub>7</jats:sub>)<jats:sub>100–<jats:italic>x</jats:italic> </jats:sub> B<jats:sub> <jats:italic>x</jats:italic> </jats:sub> alloy, coatings were prepared by laser cladding. The coatings—mainly composed of TiCr, Fe<jats:sub>0.1</jats:sub>Ti<jats:sub>0.18</jats:sub>V<jats:sub>0.72</jats:sub>, CoTi, Ti<jats:sub>2</jats:sub>Ni, and TiB—and amorphous phases were investigated in terms of microstructure, wear resistance, and corrosion resistance. The results showed that the microhardness of the Co-based coatings first increased and then decreased with the increase of B content. When the B content was 6%, the microhardness of the coating increased up to 1210 HV<jats:sub>0.2</jats:sub> which was 3.4 times that of TC4 alloy substrate. The coatings exhibited diverse wear mechanisms that gradually transitioned from severe fatigue spalling and oxidative wear to slightly abrasive wear. The corrosion current density of Co-based coatings in 3.5 wt% NaCl solution first increased and then decreased as B contents increased. Coatings with 4% B content, however, exhibited the best corrosion resistance, which was most suitable for improving the corrosion resistance of Ti alloy.","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"21 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140598170","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":"Residual fly ash from pyrometallurgical processes as a partial replacement for Portland cement in mortars: a study of structural evolution and determination of compressive strength","authors":"J. C. Juarez-Tapia, H. García-Ortiz, M. Pérez-Labra, J. A. Romero-Serrano, M. Reyes-Pérez, A. Hernández-Ramirez, V. Acosta-Sanchez, A.M. Teja-Ruiz, I.A. Reyes-Dominguez","doi":"10.2478/msp-2023-0050","DOIUrl":"https://doi.org/10.2478/msp-2023-0050","url":null,"abstract":"Mortar mixtures were prepared by partial replacement of Portland cement with 0%, 10%, and 15% of residual fly ash to determine the structural evolution and compressive strength at 3, 7, 14, and 28 days. Portlandite, calcite, ettringite, iron oxide, silicon oxide, and sillimanite were identified in the standard mortar, and, additionally, magnetite was identified in the mortar with 10% and 15% fly ash. X-ray diffraction peaks corresponding to portlandite and ettringite increased in intensity with increasing curing time as a result of the consolidation of mineral species. The SEM analysis revealed that the standard mortar contained mainly portlandite and ettringite at 28 days, while the samples with 10% and 15% fly ash contained particles of fly ash coated with portlandite and ettringite, particles with a smooth surface, and particles of fly ash with signs of attack on their surfaces. The sc increased when the age of the mortar and the substitution of Portland cement by fly ash was increased from 3 to 28 days and from 0 to 15%, respectively.","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"67 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140598055","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":"Investigation of silver nanoparticles embedded in extracted gelatins from camel, bovine, and fish bones for possible use in radiation dosimetry","authors":"Thaar K. Alrashidi, Alwaleed Aljuhani, Faisal Almugaiteeb, Nacer Badi, Hatem A. Al-Aoh, Saleh A. Alghamdi, Abdulrhman M Alsharari, Ahmed Obaid M Alzahrani, Khaled Almalki","doi":"10.2478/msp-2023-0043","DOIUrl":"https://doi.org/10.2478/msp-2023-0043","url":null,"abstract":"Gelatins from camel, bovine, and fish bones were successfully extracted by using chemical pretreatment and heating methods. The bones were demineralized for 3 days at ambient temperature using hydrochloric acid solutions (0.5–1 M), and the collagen was partially hydrolyzed by preheating in distilled water at 75–80°C for 3 h, followed by extraction temperature at 90°C for 1 h. Free-standing films of gelatin entrained with silver nanoparticles (Gel/AgNPs) at low concentrations (1.25, 2.5, and 5 mM) were synthesized as radiation dosimeters. A high-energy ultrasonic homogenizer was used to dissolve the gelatin in distilled water and to disperse the AgNPs in the gelatin. The nanocomposites’ morphology and crystallinity were investigated using scanning electron microscopy (SEM), optical absorption, and Fourier transform infrared (FTIR) spectroscopies. Dose enhancement was assessed using X-ray irradiations with beam energies below and above silver K-edge. The beam was configured by setting the X-ray generator at 15, 25.5, and 35 kV potential and a beam current of 1 mA. An X-ray detector is used to detect the number of electrons after passing through Gel/AgNPs samples. The use of AgNPs embedded in gelatin caused the enhancement of X-ray radiation absorption, and the highest percentage of linearity for the dosimeter was found to be 90% in the optical range of 395 nm to 425 nm. The preliminary results demonstrated that Gel/AgNPs material may be used in radiation dosimetry for low-energy radiotherapy sources.","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"21 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140598164","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":"Synergistic emulsification of polyetheramine/nanofluid system as a novel viscosity reducer of acidic crude oil","authors":"Yang Cao, Yanlin Guo, Tao Wu, Dejun Sun","doi":"10.2478/msp-2023-0049","DOIUrl":"https://doi.org/10.2478/msp-2023-0049","url":null,"abstract":"Oil is a critical raw material for energy and industry, the depletion of conventional oil reserves necessitates efficient extraction and production of unconventional resources like acidic crude oil. However, its high viscosity poses significant challenges for transportation and processing. To address these challenges, this study developed a novel emulsion viscosity reducer. We designed a nanofluid based on a synergistic polyetheramine/nanofluid system consisting of alkyl ethoxy polyglycosides (AEG) as a green surfactant, SiO<jats:sub>2</jats:sub> nanoparticles, and an organic alkali polyetheramine. The mixture was evaluated for its viscosity reduction and emulsification performance with acidic crude oi obtained from Qinghe oil production plant in Shengli Oilfield. The results showed that the optimized viscosity reducer achieved a remarkable reduction rate of 98.1% at 50◦C in crude oil viscosity from 6862 mPa·s to 129 mPa·s. This demonstrated the reducer effectively transformed acidic crude oil into a low viscosity oil-in-water (O/W) emulsion with high stability. Furthermore, the core imbibition simulation tests demonstrated that the viscosity reducer could improve the recovery of acidic crude oil from 29.6% to 49.4%, indicating the potential application of the optimized viscosity reducer in the exploitation of acidic crude oil. In conclusion, this study developed a novel emulsion viscosity reducer, which can reduce the viscosity and improve recovery of acidic crude oil by emulsifying into O/W emulsion. The optimized formula has potential for practical application in the exploitation of acidic crude oil.","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"47 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140312276","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":"Mechanical and corrosion properties of highly porous Ta-Nb-Sn alloy for intervertebral disc in spinal applications","authors":"Berk Atay, Ilven Mutlu","doi":"10.2478/msp-2023-0048","DOIUrl":"https://doi.org/10.2478/msp-2023-0048","url":null,"abstract":"In this study, low Young’s modulus, highly porous Ta-Nb-Sn alloy foam was manufactured by using the space holder method. The aim of this study is development of an alloy with high wear resistance, with Young’s modulus, with good imaging (MRI, CT) properties, and with high bioactivity. Ta alloy foam can be used in spinal applications (intervertebral disc) or dental applications. The space holder method enables the manufacturing of open-cell foam with a low elastic modulus. Powder mixtures were prepared through mechanical alloying. Carbamide was used to form pores. Ta has suitable strength, ductility, corrosion resistance, and biocompatibility. Ta has high price, however, and a high melting temperature, high activity, and high density. Nb addition lowered the melting temperature, elastic modulus, and cost of using Ta. The sinterability of Ta was enhanced by Sn addition. The corrosion behaviour of Ta alloy was examined. Young’s modulus was determined by compression and ultrasonic tests. Tomography and radiography tests were also used.","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"31 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140204165","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":"Prediction of microstructural evolution in fly ash-modified cementitious system: A computational study","authors":"Andualem E. Yadeta, Pradeep K. Goyal, Raju Sarkar","doi":"10.2478/msp-2023-0044","DOIUrl":"https://doi.org/10.2478/msp-2023-0044","url":null,"abstract":"The intricate interaction between supplementary cementitious materials (SCMs) and cementitious systems profoundly influences the performance and sustainability of cementitious composites. This study explores the microstructural evolution of fly ash (FA)-modified cement paste by employing a three-dimensional cement hydration and microstructure development (CEMHYD3D) modeling package. Through comprehensive simulations, the influence of varying FA content on hydration phase evolution and pore structure within the cementitious system is revealed. As the proportion of FA within the cementitious mixtures increases, there is a substantial enhancement in the rate of hydration. Notably, the incorporation of FA introduces a significant augmentation in the hydration rate, a phenomenon with potential implications for the long-term performance of FA-modified cementitious materials. The prediction results also highlight that increasing FA substitution in cement leads to finer and more interconnected pore networks due to the pozzolanic reaction. These perceptions hold significant implications for optimizing cementitious mixes and advancing sustainable construction practices. The model-predicted results have been validated with experiments, and they are successful in predicting the microstructural evolution in FA-modified cement paste. In summary, the prediction model bridges the theoretical and practical implementation gaps by providing a thorough understanding of the microstructural evolution of FA-modified cement paste. Furthermore, it provides invaluable guidance for tailoring FA-blended cement compositions, thus promoting their enhanced performance and sustainability in the realm of cementitious materials.","PeriodicalId":18269,"journal":{"name":"Materials Science-Poland","volume":"37 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140204169","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}