Macromolecular Materials and Engineering最新文献_第3页

Poly(ethylene-glycol)-Dimethacrylate (PEGDMA) Composite for Stereolithographic Bioprinting 用于立体光刻生物打印的聚乙二醇-二甲基丙烯酸酯 (PEGDMA) 复合材料

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-29 DOI: 10.1002/mame.202400143

Shu-Yung Chang, Joseph Zhi Wei Lee, Anupama Sargur Ranganath, Terry Ching, Michinao Hashimoto

{"title":"Poly(ethylene-glycol)-Dimethacrylate (PEGDMA) Composite for Stereolithographic Bioprinting","authors":"Shu-Yung Chang, Joseph Zhi Wei Lee, Anupama Sargur Ranganath, Terry Ching, Michinao Hashimoto","doi":"10.1002/mame.202400143","DOIUrl":"10.1002/mame.202400143","url":null,"abstract":"Recent progress in additive manufacturing has enabled the application of stereolithography (SLA) in bioprinting to produce 3D biomimetic structures. Bioinks for SLA often require synthetic polymers as supplements to ensure the structural integrity of the printed cell-laden constructs. High molecular weight (MW) poly(ethylene-glycol)-diacrylate (PEGDA) (MW ≥ 3400 Da) is commonly used to enhance the mechanical property of crosslinked hydrogels. However, the production of bioink with high MW PEGDA requires in-house polymer synthesis or the acquisition of costly reagents, which may not be readily available in all laboratory settings. As an alternative to high MW PEGDA, this research investigated the use of poly(ethylene-glycol)-dimethacrylate (PEGDMA) (MW = 1000 Da) as a supplement of a bioink to enhance the mechanical properties of the SLA-printed constructs. The successful demonstration showcases 1) the fabrication of 3D constructs with overhang and complex architecture, and 2) the cytocompatibility, with high cell viability of 71–87% over 6 days of culture, of the GelMA-PEGDMA bioink to enable cell-laden bioprinting. This study suggests PEGDMA as a viable supplement in the formulation of SLA bioink. The accessibility to PEGDMA will facilitate the advance in 3D bioprinting to fabricate complex bioinspired structures and tissue surrogates for biomedical applications.","PeriodicalId":18151,"journal":{"name":"Macromolecular Materials and Engineering","volume":"309 11","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mame.202400143","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Electrospun Fiber-Based Tubular Structures as 3D Scaffolds to Generate In Vitro Models for Small Intestine 将电纺纤维管状结构作为三维支架生成小肠体外模型

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-27 DOI: 10.1002/mame.202400123

Lorenzo Zavagna, Eligio F. Canelli, Bahareh Azimi, Fabiola Troisi, Lorenzo Scarpelli, Teresa Macchi, Giuseppe Gallone, Massimiliano Labardi, Roberto Giovannoni, Mario Milazzo, Serena Danti

{"title":"Electrospun Fiber-Based Tubular Structures as 3D Scaffolds to Generate In Vitro Models for Small Intestine","authors":"Lorenzo Zavagna, Eligio F. Canelli, Bahareh Azimi, Fabiola Troisi, Lorenzo Scarpelli, Teresa Macchi, Giuseppe Gallone, Massimiliano Labardi, Roberto Giovannoni, Mario Milazzo, Serena Danti","doi":"10.1002/mame.202400123","DOIUrl":"10.1002/mame.202400123","url":null,"abstract":"Recently, in vitro models emerge as valuable tools in biomedical research by enabling the investigation of complex physiological processes in a controlled environment, replicating some traits of interest of the biological tissues. This study focuses on the development of tubular polymeric scaffolds, made of electrospun fibers, aimed to generate three-dimensional (3D) in vitro intestinal models resembling the lumen of the gut. Polycaprolactone (PCL) and polyacrylonitrile (PAN) are used to produce tightly arranged ultrafine fiber meshes via electrospinning in the form of continuous tubular structures, mimicking the basement membrane on which the epithelial barrier is formed. Morphological, physical, mechanical, and piezoelectric properties of the PCL and PAN tubular scaffolds are investigated. They are cultured with Caco-2 cells using different biological coatings (i.e., collagen, gelatin, and fibrin) and their capability of promoting a compact epithelial layer is assessed. PCL and PAN scaffolds show 42% and 50% porosity, respectively, with pore diameters and size suitable to impede cell penetration, thus promoting an intestinal epithelial barrier formation. Even if both polymeric structures allow Caco-2 cell adhesion, PAN fiber meshes best suit many requirements needed by this model, including highest mechanical strength upon expansion, porosity and piezoelectric properties, along with the lowest pore size.","PeriodicalId":18151,"journal":{"name":"Macromolecular Materials and Engineering","volume":"309 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mame.202400123","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Speckle Pattern Analysis of PVK:rGO Composite Based Memristor Device 基于 PVK:rGO 复合材料的 Memristor 器件的斑点图谱分析

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-26 DOI: 10.1002/mame.202400213

Ramin Jamali, Madeh Sajjadi, Babak Taherkhani, Davood Abbaszadeh, Ali-Reza Moradi

{"title":"Speckle Pattern Analysis of PVK:rGO Composite Based Memristor Device","authors":"Ramin Jamali, Madeh Sajjadi, Babak Taherkhani, Davood Abbaszadeh, Ali-Reza Moradi","doi":"10.1002/mame.202400213","DOIUrl":"10.1002/mame.202400213","url":null,"abstract":"The memristors are expected to be fundamental devices for neuromorphic systems and switching applications. The device made of a sandwiched layer of poly(N- vinylcarbazole) and reduced graphene composite between asymmetric electrodes (ITO/PVK:rGO/Al) exhibits bistable resistive switching behavior. The performance of the memristor can be optimized by controlling the doped graphene oxide. To assess the device performance when it switches between ON and OFF states, optical characterization approaches are highly promising due to their non-destructive and remote nature. Here, speckle pattern (SP) analysis to this end is introduced. SPs include a huge amount of information about their generating mechanism, which is extracted through statistical elaboration. SPs of the PVK:rGO in different states in situ and examine the conduction mechanism is acquired. The variations in the statistical parameters are attributed to the resistance state of the PVK:rGO with regard to the physical switching mechanism. The resistance/conduction state, in turn, depends on the activity and properties of PVK:rGO memristors, as well as the additional non-uniformities induced through the variations of density of carriers. The present optical methodology can be potentially served as a bench-top device for characterization purposes of similar devices during their operating.","PeriodicalId":18151,"journal":{"name":"Macromolecular Materials and Engineering","volume":"309 12","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mame.202400213","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Assessing Extraction Methods and Mechanical and Physicochemical Properties of Algerian Yucca Fibers for Sustainable Composite Reinforcement 评估用于可持续复合材料加固的阿尔及利亚丝兰纤维的提取方法及机械和物理化学特性

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-20 DOI: 10.1002/mame.202400082

Mohamed Amine Kacem, Moussa Guebailia, Nassila Sabba, Said Abdi, Mahdi Bodaghi

{"title":"Assessing Extraction Methods and Mechanical and Physicochemical Properties of Algerian Yucca Fibers for Sustainable Composite Reinforcement","authors":"Mohamed Amine Kacem, Moussa Guebailia, Nassila Sabba, Said Abdi, Mahdi Bodaghi","doi":"10.1002/mame.202400082","DOIUrl":"10.1002/mame.202400082","url":null,"abstract":"The utilization of biofiber in recent years has significantly increased due to its advantages like being environmentally friendly, availability, and low costs. This paper investigates the physicochemical, mechanical, and morphological properties of the yucca fiber extracted by three methods such as water-retting, traditional, and chemical methods. These analyses are designed to evaluate the extraction methodology and the hypothesis of the influence of harvesting location and growth conditions of the fiber. Various technologies are used, such as SEM, FTIR, XRD, and tensile tests. The fiber extracted by water retting is the strongest in the mechanical analysis with a strength of 690.48 MPa, followed by fiber extracted with the traditional method with 685.48 MPa, also 673.06, 657.94, 373.68 MPa for the fiber extracted by the chemical method using 3%, 5%, 10%NaOH respectively. The fiber obtained by the water retting method also has a higher chemical composition with 80.25% cellulose, 10.45% lignin, and 13.75% hemicellulose. The morphological characteristics are examined using Scanning Electron Microscopy. The crystallinity index ranged from 61.75% to 70.77%, and crystallite size from 1.73 to 2.04 nm is calculated from the XRD analysis. All these results confirm that yucca fiber can be a good sustainable choice for composite reinforcement.","PeriodicalId":18151,"journal":{"name":"Macromolecular Materials and Engineering","volume":"309 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mame.202400082","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Graphene Oxide-Incorporated Polylactic Acid/Polyamidoamine Dendrimer Electroconductive Nanocomposite as a Promising Scaffold for Guided Tissue Regeneration 石墨烯氧化物掺杂聚乳酸/聚酰胺胺树枝状聚合物导电纳米复合材料有望成为引导组织再生的支架

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-19 DOI: 10.1002/mame.202400100

Fatemeh Koeini, Atefeh Solouk, Somaye Akbari

{"title":"Graphene Oxide-Incorporated Polylactic Acid/Polyamidoamine Dendrimer Electroconductive Nanocomposite as a Promising Scaffold for Guided Tissue Regeneration","authors":"Fatemeh Koeini, Atefeh Solouk, Somaye Akbari","doi":"10.1002/mame.202400100","DOIUrl":"10.1002/mame.202400100","url":null,"abstract":"In the recent years, electroconductive scaffolds have shown promising capabilities in guided regeneration of electroactive tissues including nerve, heart muscle, bone, cartilage, and skin. Herein, the fabrication of a novel electroconductive poly (L-lactic acid) (PLLA)/polyamidoamine (PAMAM) dendrimer nanofibrous scaffold containing graphene oxide (GO) nanosheets is described. The presence of PAMAM with amine terminal groups successfully aminolyzed PLLA. Interestingly, both PAMAM (5% w/w) and GO (0.5, 1, 2% w/w) not only contributed to reducing the fiber diameter, increasing the hydrophilicity and degradation rate, but also provided a nanocomposite scaffold with enhancement in electrical conductivity. By incorporating 1% w/w of GO, the nanocomposite scaffold exhibited optimized properties, including electrical conductivity (≈3.09 × 10−5 S m−1), crystallinity (≈ 47%), Young's modulus (≈16.95 MPa), as well as strength (≈1.58 MPa). This nanocomposite also demonstrated significant antibacterial activity of ≥ 90% against both gram-positive and gram-negative bacteria. Cellular assays confirmed acceptable cytocompatibility of the nanocomposite scaffolds containing GO and PAMAM, which can support the viability and proliferation of PC-12 cells. In conclusion, the presence of GO nanosheets alongside PAMAM dendrimers can synergically promote the properties of the prepared nanofibrous mats which can be used as potential electroconductive scaffolds for guided tissue regeneration.","PeriodicalId":18151,"journal":{"name":"Macromolecular Materials and Engineering","volume":"309 11","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mame.202400100","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142197211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Evaluation of Burn Wound Healing Efficacy and Biocompatibility of Centella asiatica Mediated Synthesised AgNPs Loaded Hybrid Nanofiber Scaffold: In Vitro and In Vivo Studies 评估积雪草介导合成的 AgNPs 负载混合纳米纤维支架的烧伤伤口愈合功效和生物相容性：体外和体内研究

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-18 DOI: 10.1002/mame.202400186

Ogün Bozkaya, Esra Bozkaya, Hüsamettin Ekici, Mehmet Eray Alçığır, Yaşar Şahin, Nebahat Aytuna Çerçi, Siyami Karahan, Mustafa Yiğitoğlu, İbrahim Vargel

{"title":"Evaluation of Burn Wound Healing Efficacy and Biocompatibility of Centella asiatica Mediated Synthesised AgNPs Loaded Hybrid Nanofiber Scaffold: In Vitro and In Vivo Studies","authors":"Ogün Bozkaya, Esra Bozkaya, Hüsamettin Ekici, Mehmet Eray Alçığır, Yaşar Şahin, Nebahat Aytuna Çerçi, Siyami Karahan, Mustafa Yiğitoğlu, İbrahim Vargel","doi":"10.1002/mame.202400186","DOIUrl":"10.1002/mame.202400186","url":null,"abstract":"The aim of this study is to evaluate the cell responses, potential skin reactions during the treatment process and burn wound healing efficacy of electrospun polycaprolactone/polyethylene oxide (PCL/PEO) nanofibers (NFs) containing Centella asiatica mediated synthesized silver nanoparticles (CA-AgNPs) by in vitro and in vivo studies. Apoptosis-necrosis, genotoxicity, hemolysis, and cell attachment studies are carried out within the scope of in vitro tests, and irritation, sensitivity, and burn wound studies are carried out within the scope of in vivo tests. The apoptotic index value of CA-AgNPs-[PCL/PEO] NFs material on L929 fibroblast cells is determined as 5.0 ± 1.0% at the highest concentration and the necrotic index value is 5.0 ± 0.3%. Micronucleus rates (%) of NFs treated with CHO (Chinese Hamster Ovary) cells are not at genotoxic level. The hemolytic index value of NFs dressing is determined as 0.23 ± 0.03%, The primary irritation index (PII) value of NFs wound dressing is calculated as 0.36 by irritation tests. In addition, the potential sensitization reaction of NFs extract on guinea pigs is evaluated and the sensitization score is determined as 0.9. The healing efficacy of NFs material on second-degree burn wounds compared to a commercial product is supported by pathomorphological findings.","PeriodicalId":18151,"journal":{"name":"Macromolecular Materials and Engineering","volume":"309 12","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mame.202400186","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142197210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Adhesion and Cohesion Performance of Polyurethane Made of Bio-Polyol Derived from Modified Waste Cooking Oil for Exterior Grade Plywood 改性烹饪废油中提取的生物多元醇制成的聚氨酯在户外级胶合板中的粘合力和内聚力性能

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-16 DOI: 10.1002/mame.202400225

Sena Maulana, Ika Putri Setiawan, Dyah Pusbanarum, Petar Antov, Apri Heri Iswanto, Lubos Kristak, Seng Hua Lee, Muhammad Adly Rahandi Lubis

{"title":"Adhesion and Cohesion Performance of Polyurethane Made of Bio-Polyol Derived from Modified Waste Cooking Oil for Exterior Grade Plywood","authors":"Sena Maulana, Ika Putri Setiawan, Dyah Pusbanarum, Petar Antov, Apri Heri Iswanto, Lubos Kristak, Seng Hua Lee, Muhammad Adly Rahandi Lubis","doi":"10.1002/mame.202400225","DOIUrl":"10.1002/mame.202400225","url":null,"abstract":"This study explored the feasibility of Waste Cooking Oil (WCO)-based Bio-Polyurethane (Bio-PU) as an eco-friendly alternative to petroleum-derived polyols in plywood adhesives. The objective is to evaluate the impact of varied WCO concentrations and methylene diphenyl diisocyanate (MDI) levels on Bio-PU and plywood performance. The Bio-PU's characteristics, rheology, and functional groups are studied. Plywood made from three layers of 100 mm x 100 mm × 2 mm rubberwood (Hevea brasiliensis) veneer is bonded with Bio-PU using a dual spread approach at 180 g.m−2, hot pressed at 120 °C and 1 MPa for 4 min. The laboratory-fabricated plywood is tested for physical, mechanical, and adhesive properties. Results showed that Bio-PU exhibited unique adhesive characteristics, with excellent adhesive strength, despite a slight decrease with higher WCO concentrations. WCO insertion do not compromise delamination resistance. FTIR analysis confirmed successful polyurethane chain synthesis. This research highlighted the potential of WCO-based Bio-PU's as a sustainable, high-performance plywood adhesive.","PeriodicalId":18151,"journal":{"name":"Macromolecular Materials and Engineering","volume":"309 12","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mame.202400225","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142197212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Polymer Science in South Africa 南非的聚合物科学

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-14 DOI: 10.1002/mame.202470015

Rueben Pfukwa, Suprakas Sinha Ray

引用次数: 0

Masthead: Macromol. Mater. Eng. 8/2024 刊头：Macromol.Mater.Eng.8/2024

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-14 DOI: 10.1002/mame.202470016

引用次数: 0

Anti-Inflammatory Drugs-Modified Poly(2-Hydroxyethyl Methacrylate) Particles as Anticancer Drug Carriers 作为抗癌药物载体的抗炎药物改性聚（2-羟乙基甲基丙烯酸酯）颗粒

IF 4.2 3区材料科学

Macromolecular Materials and Engineering Pub Date : 2024-08-13 DOI: 10.1002/mame.202400147

Shima Ghaffari, Marzieh Golshan, Kiyumars Jalili, Mehdi Salami-Kalajahi

{"title":"Anti-Inflammatory Drugs-Modified Poly(2-Hydroxyethyl Methacrylate) Particles as Anticancer Drug Carriers","authors":"Shima Ghaffari, Marzieh Golshan, Kiyumars Jalili, Mehdi Salami-Kalajahi","doi":"10.1002/mame.202400147","DOIUrl":"10.1002/mame.202400147","url":null,"abstract":"In this work, 2-hydroxyethyl methacrylate (HEMA) is modified by ibuprofen and diclofenac as anti-inflammatory drugs to synthesize ibuprofen-HEMA and diclofenac-HEMA monomers. Then, poly(ibuprofen-HEMA-co-HEMA) (PIHH), poly(diclofenac-HEMA-co-HEMA) (PDHH), and poly(2-hydroxyethyl methacrylate) (PHEMA) particles are prepared by distillation precipitation polymerization. The morphology and size of the particles are investigated by dynamic light scattering (DLS) and field emission scanning electron microscopy (FE-SEM). It is observed that all particles are spherical and with sizes of 298.3 nm for PHEMA, 178.8 nm for PDHH, and 85.2 nm for PIHH, respectively. Doxorubicin drug is loaded into the prepared particles and the drug release behavior is investigated for all the particles at two different pH values of 7.4 and 5.3. The release of the drug in acidic pH is higher due to the better solubility of DOX in acidic environment and the faster release of DOX molecules from nanocarriers. The toxicity of particles is also investigated and it is observed that by loading the drug into the PHEMA particles, the release of the drug causes fewer toxic effects than in the free state (drug without any nanocarrier), and the presence of ibuprofen and diclofenac in the particles, that is, PIHH and PDHH, led to a significant reduction in the cytotoxicity.","PeriodicalId":18151,"journal":{"name":"Macromolecular Materials and Engineering","volume":"309 11","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mame.202400147","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142197213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0