Materials Research Express最新文献_第2页

Early length changes and microscopic phase analysis of phosphorus hemihydrate gypsum fireproof mortar 半水磷石膏防火砂浆的早期长度变化和显微相分析

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad75e6

Wang Xuebing and Yuanyuan Wang

{"title":"Early length changes and microscopic phase analysis of phosphorus hemihydrate gypsum fireproof mortar","authors":"Wang Xuebing and Yuanyuan Wang","doi":"10.1088/2053-1591/ad75e6","DOIUrl":"https://doi.org/10.1088/2053-1591/ad75e6","url":null,"abstract":"Coating the surface of steel structures with phosphohemihydrate gypsum fireproof mortar can improve the fire resistance of steel structures. The hydration curve of phosphorus hemihydrate gypsum (PHG) showed a monotonic increasing trend, and the hydration time was about 1 day. In order to study the hydration process of phosphorus hemihydrate gypsum fireproof mortar, its length change in the early hardening stage was experimentally investigated. The results showed that compared with the hydration time of phosphohemihydrate gypsum, the duration of early length changes in phosphohemihydrate gypsum fireproof mortar was significantly prolonged to about 4 days, and four intervals were clearly observed during this process. Hydroxypropyl methyl cellulose (HPMC) as a water retaining agent, hydroxypropyl starch ether (HPS) as a thixotropic agent, and dispersed latex powder (LP) can all make the four intervals of length changes of fireproof mortar more significant. After adding HPMC, HPS, and LP, it can promote the formation of dihydrate gypsum mainly in fireproof mortar, but dihydrate gypsum crystals were more likely to grow along the [021] direction. The addition of additives can also effectively improve the pore structure of phosphogypsum fireproof mortar.","PeriodicalId":18530,"journal":{"name":"Materials Research Express","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181213","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}

引用次数: 0

Effectiveness of Xanthan Gum-based composite in repairing cracks in reinforced concrete structures 黄原胶基复合材料修复钢筋混凝土结构裂缝的效果

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad719d

Asvitha Valli S and Ravi Kumar M S

{"title":"Effectiveness of Xanthan Gum-based composite in repairing cracks in reinforced concrete structures","authors":"Asvitha Valli S and Ravi Kumar M S","doi":"10.1088/2053-1591/ad719d","DOIUrl":"https://doi.org/10.1088/2053-1591/ad719d","url":null,"abstract":"This study investigates the enhancement of concrete slabs using a biopolymer-modified cementitious repair material (CXT) composed of Ordinary Portland Cement, Xanthan Gum, and Tartaric Acid Powder. The innovative formulation of CXT aims to improve the mechanical properties of repaired concrete structures. Experimental results demonstrate that CXT significantly enhances mechanical properties such as the load-bearing capacity of concrete slabs. Non-destructive testing methods, including the Rebound Hammer test and Ultrasonic Pulse Velocity (UPV), as well as destructive testing methods, were employed to evaluate the performance of CXT in repairing cracks. The study highlights the improved load-bearing capacity and structural integrity of CXT-repaired slabs, contributing to increased longevity and reduced maintenance costs of concrete structures. Furthermore, the sustainability metrics of CXT, including Process Mass Intensity (PMI), Energy Intensity (EI), Environmental Factor (E-Factor), and Reaction Mass Efficiency (RME), are evaluated, illustrating its cost-effectiveness and environmental benefits. This comprehensive approach underscores the potential of CXT as a durable and sustainable repair material for concrete infrastructure.","PeriodicalId":18530,"journal":{"name":"Materials Research Express","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181178","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}

引用次数: 0

Characterization of wood plastic composites made with recycled waste tire rubber 用回收废轮胎橡胶制成的木塑复合材料的特性分析

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad72d1

Behnam Shaneei, Mohammad Hadi Rezvani, Mohammad Ghofrani, Aujchariya Chotikhun and Nadir Ayrilmis

{"title":"Characterization of wood plastic composites made with recycled waste tire rubber","authors":"Behnam Shaneei, Mohammad Hadi Rezvani, Mohammad Ghofrani, Aujchariya Chotikhun and Nadir Ayrilmis","doi":"10.1088/2053-1591/ad72d1","DOIUrl":"https://doi.org/10.1088/2053-1591/ad72d1","url":null,"abstract":"Green materials are currently demanded for construction as well as other products since the 26th UN Climate Change Conference of the Parties (COP26) in 2021. Using renewable and sustainable resources to innovate new materials such as composites is encouraged. This study aimed to investigate the physical and mechanical characteristics of wood plastic composites (WPCs) when adding waste tire rubber as filler for 10% or 20% by weight. The results showed that the density of the WPC samples (50 wt% wood − 50 wt% high density polyethylene) increased with the addition of the waste tire rubber (WTR) while the dimensional stability of samples was reduced. The mechanical properties of the WPC samples were determined, including flexural strength, flexural modulus, elongation at break, tensile strength, tensile modulus, and impact strength. The WTR as filler in the WPC tended to decrease the tensile strength and flexural strength whereas it improved the impact strength of materials. The results indicated that the WTR as recycled material in WPC affected the physical and mechanical properties of the WPCs. Although the use of the WTR in the production of the WPC adversely affects the mechanical properties, the use of 10 wt% WTR was acceptable. The results of the study showed that the addition of the WTR to the WPC production process can be useful for its recycling and for reducing the cost of the WPC.","PeriodicalId":18530,"journal":{"name":"Materials Research Express","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181181","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}

引用次数: 0

Effect of layering sequence and jujube fruit seed addition on the mechanical, water absorption and bio-degradation properties of Indian almond/peepal hybrid composites 分层顺序和枣果种子添加量对印度杏/柚杂交复合材料的机械、吸水和生物降解性能的影响

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad6ff6

R Srinivasan and M Jayaraman

{"title":"Effect of layering sequence and jujube fruit seed addition on the mechanical, water absorption and bio-degradation properties of Indian almond/peepal hybrid composites","authors":"R Srinivasan and M Jayaraman","doi":"10.1088/2053-1591/ad6ff6","DOIUrl":"https://doi.org/10.1088/2053-1591/ad6ff6","url":null,"abstract":"Hybrid composite comprised fibers like peepal and Indian almond was fabricated, with the addition of natural filler such as jujube fruit seed particles aimed at enhancing composite performance. The impact of jujube fruit seed particles and layering sequence on the mechanical properties, water absorption and bio-degradation of the composites was investigated. Initially, two composite types, IA/P/IA (Indian almond/Peepal/Indian almond) and P/IA/P (Peepal/Indian almond/Peepal), were produced using hand layup practice, altering layering sequence of fibers. Based on tensile test results, the P/IA/P composite emerged as the optimal choice due to the denser packing of high-strength peepal fiber. Subsequently, jujube fruit seed particles were incorporated into the P/IA/P composite at varying weight percentages ranging from 2.5 to 10 with a step size of 2.5. The effect of jujube fruit seed particles on the performance of the P/IA/P composite was examined. The P/IA/P/7.5 wt% jujube composite demonstrated superior tensile, flexural, impact, and hardness properties, recording values of 82 MPa, 98 MPa, 5.2 kJ m−2, and 86 shore-d, respectively. These values were 15.4%, 22.5%, 20.9%, and 4.8% higher than those of the P/IA/P composite. The P/IA/P/10 wt% jujube composite demonstrated minimal water absorption, with only 8% recorded over a 12-day period, as well as limited mass loss, totaling 27% over 60 days. Consequently, this research suggests that the P/IA/P/7.5 wt% composite holds promise for industrial applications.","PeriodicalId":18530,"journal":{"name":"Materials Research Express","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181207","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}

引用次数: 0

ZnO-modified glass capillaries as a portable photocatalytic reactor for real-time measurements 氧化锌改性玻璃毛细管作为用于实时测量的便携式光催化反应器

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad718c

Shefali Jayswal and Saswat Mohapatra

引用次数: 0

Evaluation of wear resistance of CrN, CrAlN, and TiAlN coatings deposited by multi-arc ion plating on spinning die of Cr12MoV 通过多弧离子镀沉积在 Cr12MoV 纺丝模上的 CrN、CrAlN 和 TiAlN 涂层的耐磨性评估

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad7350

Rongchuan Lin, Shilong Sun, Bin You, Tianlei Dong, Yusheng Sui and Shasha Wei

{"title":"Evaluation of wear resistance of CrN, CrAlN, and TiAlN coatings deposited by multi-arc ion plating on spinning die of Cr12MoV","authors":"Rongchuan Lin, Shilong Sun, Bin You, Tianlei Dong, Yusheng Sui and Shasha Wei","doi":"10.1088/2053-1591/ad7350","DOIUrl":"https://doi.org/10.1088/2053-1591/ad7350","url":null,"abstract":"This study successfully deposited CrN, CrAlN, and TiAlN coatings on the surface of Cr12MoV substrate using multi-arc ion plating (MAIP). The influence of phase composition and surface morphology on the hardness, adhesion strength, friction performance, and wear mechanisms of these coatings was investigated, with a comparative analysis of their wear resistance. Nanoindentation results revealed that the hardness (H) of CrN, CrAlN, and TiAlN coatings increased by 70.37%, 74.97%, and 75.64%, respectively, compared to the substrate. The hardness (H) and elastic modulus (E) were found to be positively correlated. CrAlN demonstrated superior resistance to deformation, reflected in its higher H/E and H3/E2 radios compared to the CrN and TiAlN. Adhesion tests showed that CrAlN had the strongest adhesion strength to the substrate, with an adhesion force of 81.55 N, representing a 14.78% and 8.46% improvement over CrN and TiAlN, respectively. Friction and wear tests identified CrAlN as having the lowest friction coefficient (0.389), attributed to its high hardness and strong adhesion. The wear mechanisms of CrAlN observed were primarily mild abrasive wear, oxidative wear, and adhesive wear. In comparison, CrN and TiAlN coatings exhibited higher friction coefficients of 0.424 and 0.391, respectively, due to their lower hardness and adhesion, which led to more severe oxidative and abrasive wear. Additionally, the TiAlN coating showed signs of brittle failure in wear scars, likely due to the formation of Al2O3 oxides during wear.","PeriodicalId":18530,"journal":{"name":"Materials Research Express","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181182","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}

引用次数: 0

Learning based model for predicting mechanical properties and sustainable filler band for NBR composites using lignin and carbon black 基于学习的木质素和炭黑丁腈橡胶复合材料机械性能和可持续填充带预测模型

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad6ff5

Antony J Kachirayil, Vaishak Nambiathodi, Bony Thomas, Radhika Raveendran, Siby Varghese, Manoj Kumar Mukundan and Raghunathan Rajesh

{"title":"Learning based model for predicting mechanical properties and sustainable filler band for NBR composites using lignin and carbon black","authors":"Antony J Kachirayil, Vaishak Nambiathodi, Bony Thomas, Radhika Raveendran, Siby Varghese, Manoj Kumar Mukundan and Raghunathan Rajesh","doi":"10.1088/2053-1591/ad6ff5","DOIUrl":"https://doi.org/10.1088/2053-1591/ad6ff5","url":null,"abstract":"Experimental determination of mechanical properties of rubber composites, such as tensile strength and hardness, involves complex multistage preparation procedures that are laborious and expensive. In this study, a hybrid filler of carbon black (CB) along with a sustainable filler of lignin is added for reinforcement in the nitrile butadiene rubber (NBR) matrix, with the total filler content varying from 10 parts per hundred rubber (phr) to 80 phr. This work aims to develop a data-driven predictive model for the mechanical properties of rubber composites. An artificial neural network (ANN) model using multilayer feed-forward back-propagation has been created to forecast the tensile strength (Ts) and hardness (Hd) of rubber composites. The model predicts the uniaxial tensile response and hardness using input parameters that include total filler and lignin loading levels. The effectiveness of the suggested prediction method was demonstrated by statistical analysis using confidence intervals, showing a prediction error between 5.47% and 3.23% for the Ts and between 3.03% and 1.85% for Hd at 95% confidence intervals. A sustainable green band could be defined in the developed model, which is handy for designers to replace CB with lignin in various NBR based products, such as hoses, seals, etc., without compromising on tensile strength and hardness.","PeriodicalId":18530,"journal":{"name":"Materials Research Express","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181177","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}

引用次数: 0

Statistical approach to explore sustainable characteristics of cellulosic Desmostachya bipinnata fiber and its chemically modified conditions 用统计方法探索纤维素双峰草纤维的可持续特性及其化学改性条件

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad7446

David Gnanaraj J, Vignesh V, Mohamed Hashem and Hassan Fouad

{"title":"Statistical approach to explore sustainable characteristics of cellulosic Desmostachya bipinnata fiber and its chemically modified conditions","authors":"David Gnanaraj J, Vignesh V, Mohamed Hashem and Hassan Fouad","doi":"10.1088/2053-1591/ad7446","DOIUrl":"https://doi.org/10.1088/2053-1591/ad7446","url":null,"abstract":"This present work has been intended to investigate the properties of an extracted Desmostachya bipinnata fibers (DBFs). The unmodified/untreated (raw), 10% sodium hydroxide (NaOH) and 0.5% potassium permanganate(KMnO4)chemically modified/treated Desmostachya Bipinnata fibers are explored to establish the possibility of designing a large scale natural product or fiber/reinforcement. The raw, alkaline treated and potassium permanganate treated Desmostachya bipinnata fibers are designated as Raw Desmostachya Bipinnata Fibers, Alkali treated Desmostachya Bipinnata Fibers and Potassium Permanganate treated Desmostachya Bipinnata Fibers as samples, respectively. Mechanical, thermal and physio-chemical behaviors and surface morphology of both RDBF and treated Desmostachya Bipinnata Fibers are analyzed. From the results obtained, it is evident that an increase in aspect ratio, due to the diameter reduction by alkalization process, has exhibited high tensile strength with minimum density. The Fourier Transform Infrared Spectroscopy results have shown variation of chemical bonding, due to different chemical treatments of DBFs. Summarily, the maximum values of Crystallinity Index (CI) and activation energy are obtained with Alkali treated Desmostachya bipinnata fibers sample.","PeriodicalId":18530,"journal":{"name":"Materials Research Express","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181205","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}

引用次数: 0

Effect of promoters on the performance of CuNi catalysts for hydrogen production from methanol decomposition 促进剂对用于甲醇分解制氢的铜镍催化剂性能的影响

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad74cd

Beidong Zhang, Yankun Jiang, Le Cong, Yexin Chen, Lunhong Chen and Zhengdong Yang

{"title":"Effect of promoters on the performance of CuNi catalysts for hydrogen production from methanol decomposition","authors":"Beidong Zhang, Yankun Jiang, Le Cong, Yexin Chen, Lunhong Chen and Zhengdong Yang","doi":"10.1088/2053-1591/ad74cd","DOIUrl":"https://doi.org/10.1088/2053-1591/ad74cd","url":null,"abstract":"Utilizing the exhaust heat from engines to decompose methanol for hydrogen production, and subsequently introducing this hydrogen into the combustion chamber, is one of the crucial approaches for achieving energy savings and emission reductions. The role of an efficient and stable catalyst for methanol decomposition is paramount in this application. Therefore, CuNi-based catalysts modified with promoters such as Zr, La, Mn, and Mg were prepared using a stepwise impregnation method. The developed catalysts were tested using various analytical methods and characterization techniques. The results indicate that the addition of the Zr enhances the dispersion of active components, improves the catalyst’s reducibility. This, in turn, enhances the catalyst’s activity and hydrogen selectivity. The hydrogen yield of the Zr modified catalyst increased by an average of 12% compared to the original catalyst. Furthermore, the Zr modified catalyst exhibits exceptional stability after prolonged use. La can enhance the low-temperature activity of the catalyst but performs poorly at high temperatures. The promoter Mn has a minimal impact on the overall performance of the catalyst. Conversely, the addition of Mg as a promoter inhibits the dispersion of active components, resulting in adverse effects on the catalyst.","PeriodicalId":18530,"journal":{"name":"Materials Research Express","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181212","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}

引用次数: 0

Microstructure and mechanical characteristics of Al1050/B2O3+Cu hybrid surface nanocomposite fabricated using friction stir processing 利用搅拌摩擦加工技术制备的 Al1050/B2O3+Cu 混合表面纳米复合材料的微观结构和力学特性

IF 2.3 4区材料科学

Materials Research Express Pub Date : 2024-09-08 DOI: 10.1088/2053-1591/ad74cc

Siamak Pedrammehr, Moosa Sajed, Sajjad Pakzad, Ahad Zare Jond, Mir Mohammad Ettefagh and Saman Tutunchilar

{"title":"Microstructure and mechanical characteristics of Al1050/B2O3+Cu hybrid surface nanocomposite fabricated using friction stir processing","authors":"Siamak Pedrammehr, Moosa Sajed, Sajjad Pakzad, Ahad Zare Jond, Mir Mohammad Ettefagh and Saman Tutunchilar","doi":"10.1088/2053-1591/ad74cc","DOIUrl":"https://doi.org/10.1088/2053-1591/ad74cc","url":null,"abstract":"In the realm of advanced materials engineering, the development of hybrid nanocomposites has garnered significant attention due to their superior mechanical properties and potential applications. The primary aim of this research is to develop a surface hybrid nanocomposite using Al1050 aluminium alloy (5 mm thickness) as the base material through friction stir processing. B2O3 nano-powder, averaging 100 nm in size, and Cu micro-powder, averaging 5 μm in size, were incorporated into the aluminium surface in various volume ratios using the Friction Stir Processing (FSP). The processing parameters included a tool rotational speed of 1250 rpm, a feed rate of 50 mm min−1, and a tilt angle of 3°. The number of passes was set at two levels: 1 and 3 passes. The influence of the volume ratio of constituents and the number of passes on the microstructure and mechanical properties of the resulting composite was thoroughly explored. The samples underwent tensile tests, microhardness tests, and metallographic examinations using both Optical Microscopy (OM) and Field Emission Scanning Electron Microscopy (FE-SEM). The composite with 25%-B2O3-75%-Cu composition exhibited the highest stress and hardness values, measuring 139 MPa and 58.14 HV, respectively. The enhanced strength of this sample is attributed to the presence of additives and the resultant grain size.","PeriodicalId":18530,"journal":{"name":"Materials Research Express","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181215","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}

引用次数: 0