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Fabrication of a Novel Hybrid Scaffold for Tissue Engineered Heart Valve
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作者 洪昊 董念国 +4 位作者 史嘉玮 陈思 郭超 胡平 齐宏旭 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2009年第5期599-603,共5页
The aim of this study was to fabricate biomatrix/polymer hybrid scaffolds using an electrospinning technique. Then tissue engineered heart valves were engineered by seeding mesenchymal stromal cells (MSCs) onto the ... The aim of this study was to fabricate biomatrix/polymer hybrid scaffolds using an electrospinning technique. Then tissue engineered heart valves were engineered by seeding mesenchymal stromal cells (MSCs) onto the scaffolds. The effects of the hybrid scaffolds on the proliferation of seed cells, formation of extracellular matrix and mechanical properties of tissue engineered heart valves were investigated. MSCs were obtained from rats. Porcine aortic heart valves were decellularized, coated with poly(3-hydroxybutyrate-co-4-hydroxybutyrate) using an electrospinning technique, and reseeded and cultured over a time period of 14 days. In control group, the decellularized valve scaffolds were reseeded and cultured over an equivalent time period. Specimens of each group were examined histologically (hematoxylin-eosin [HE] staining, immunohistostaining, and scanning electron microscopy), biochemically (DNA and 4-hydroxyproline) and mechanically. The results showed that recellularization was comparable to the specimens of hybrid scaffolds and controls. The specimens of hybrid scaffolds and controls revealed comparable amounts of cell mass and 4-hydroxyproline (P〉0.05). However, the specimens of hybrid scaffolds showed a significant increase in mechanical strength, compared to the controls (P〈0.05). This study demonstrated the superiority of the hybrid scaffolds to increase the mechanical strength of tissue engineered heart valves. And compared to the decellularized valve scaffolds, the hybrid scaffolds showed similar effects on the proliferation of MSCs and formation of extracellular matrix. It was believed that the hybrid scaffolds could be used for the construction of tissue engineered heart valves. 展开更多
关键词 tissue engineered heart valve hybrid scaffold ELECTROSPINNING mesenchymal stem cells
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Hybrid Scaffolds Composed of Amino-Acid Coated Sponge and Hydroxyapatite for Hard Tissue Formation by Bone Marrow Cells
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作者 Takayoshi Yabuuchi Masataka Yoshikawa +1 位作者 Hideyuki Kakigi Hiroyuki Hayashi 《Journal of Biomedical Science and Engineering》 2014年第6期316-329,共14页
A formalin-treated polyvinyl-alcohol (PVF) sponge is convenient as a scaffold because its configuration is easily modified. However, coating the sponge with an adhesive chemical agent is necessary to attach bone marro... A formalin-treated polyvinyl-alcohol (PVF) sponge is convenient as a scaffold because its configuration is easily modified. However, coating the sponge with an adhesive chemical agent is necessary to attach bone marrow cells (BMCs) to the sponge structure. Moreover, it was considered that a hybrid scaffold composed of a sponge and enveloped cylindrical porous hydroxyapatite (HA) would be convenient. In this study, the effect of leucine (Leu) coating on a PVF sponge was examined for osteogenesis on an HA/PVF hybrid scaffold by rat BMCs (rBMCs). In an in vivo assessment, the sponge immersed in Leu solution (10 mg/ml) was inserted into the hollow center of cylindrical HA. The sponge received 1.5 × 106 rBMCs obtained from male Fischer 344 rats. The hybrid scaffolds were then implanted subcutaneously of syngeneic rats for 6 weeks. In vitro assessment of Leu to hard tissue formation with coating on the well or addition in rBMC culture medium was also performed in a 6-well plate for 2 weeks. In vivo examinations showed the excellent effect of Leu coating on PVF sponge. Leu-coated PVF sponge in the scaffolds showed marked new bone formation in the pores by histological examination. Leu-coated PVF sponge showed a high quantity of osteocalcine (OC). HA might prevent the release of rBMCs from PVF as a barrier. In in vitro examinations, the quantity of OC in rBMC culture with and without the addition of Leu in culture medium showed no significant difference. However, addition of Leu showed significant ALP activity level in culture medium. Leu coating in culture plate wells showed no influence on the quantity of OC. It was concluded from the results that Leu might prevent the emigration of rBMCs to the outside of the scaffold and promote the differentiation of cells to osteoblasts in the scaffold. 展开更多
关键词 AMINO-ACID BONE Marrow Cells BONE FORMATION hybrid scaffold scaffold HYDROXYAPATITE Formalin-Treated Polyvinyl-Alcohol SPONGE
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3D printing of silk fibroin-based hybrid scaffold treated with platelet rich plasma for bone tissue engineering 被引量:9
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作者 Liang Wei Shaohua Wu +5 位作者 Mitchell Kuss Xiping Jiang Runjun Sun Reid Patrick Xiaohong Qin Duan Bin 《Bioactive Materials》 SCIE 2019年第1期256-260,共5页
3D printing/bioprinting are promising techniques to fabricate scaffolds with well controlled and patient-specific structures and architectures for bone tissue engineering.In this study,we developed a composite bioink ... 3D printing/bioprinting are promising techniques to fabricate scaffolds with well controlled and patient-specific structures and architectures for bone tissue engineering.In this study,we developed a composite bioink consisting of silk fibroin(SF),gelatin(GEL),hyaluronic acid(HA),and tricalcium phosphate(TCP)and 3D bioprinted the silk fibroin-based hybrid scaffolds.The 3D bioprinted scaffolds with dual crosslinking were further treated with human platelet-rich plasma(PRP)to generate PRP coated scaffolds.Live/Dead and MTT assays demonstrated that PRP treatment could obviously promote the cell growth and proliferation of human adipose derived mesenchymal stem cells(HADMSC).In addition,the treatment of PRP did not significantly affect alkaline phosphatase(ALP)activity and expression,but significantly upregulated the gene expression levels of late osteogenic markers.This study demonstrated that the 3D printing of silk fibroin-based hybrid scaffolds,in combination with PRP post-treatment,might be a more efficient strategy to promote osteogenic differentiation of adult stem cells and has significant potential to be used for bone tissue engineering. 展开更多
关键词 3D bioprinting hybrid scaffold Coating Growth factor cocktail Tissue engineering
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Single and Hybrid Design Polycaprolactone (PCL) Scaffolds: Cell Culture Study
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作者 Md Enamul Hoque Yong Leng Chuan +3 位作者 Ian Pashby Siti Sheren Aini Angela Ng Min Hwei Ruszymah Idrus 《材料科学与工程(中英文A版)》 2013年第5期315-320,共6页
关键词 体外细胞培养 混合设计 PCL 支架 聚己内酯 激光共聚焦显微镜 快速原型系统 细胞外基质
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Nanodiamond for Structural Biomimetic Scaffolds
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作者 Raffaella Aversa Relly Victoria V. Petrescu +1 位作者 Florian Ion T. Petrescu Antonio Apicella 《Journal of Materials Science and Chemical Engineering》 2018年第4期6-17,共12页
Bio-mechanically active scaffolds for tissue engineering combining hydrophilic polymeric matrix and nano-diamond fillers properties are presented and discussed in this paper. The resulting scaffolding materials reveal... Bio-mechanically active scaffolds for tissue engineering combining hydrophilic polymeric matrix and nano-diamond fillers properties are presented and discussed in this paper. The resulting scaffolding materials revealed re-markable mechanical and biological properties to be exploited in advanced biomedical applications. The novel hybrid material is based on 2 and 5 vol-ume % of detonation nano-diamond particles in a hydrophilic poly-(hydroxyl- ethyl-methacrylate) matrix. According to its mechanical and biological properties, the nanocomposite shows a hybrid nature. The base analytical procedures for the preparation of the hybrid nanocomposites and some preliminary mechanical characteristics are presented. The proposed hybrid system has been considered for potential biomimetic, osteoconductive and osteoinductive scaffolds application in bio-mechanically active bone scaffolds for osteoblast, and stem cell differentiation and growth. These more rigid hybrid nano-composites are predicted to possess improved mechanical strength overcoming the mechanical weaknesses of traditional hydrogels clinically utilized for bone regeneration. 展开更多
关键词 hybrid NANO-COMPOSITES BIOMATERIALS Bioactive scaffolds BIOENGINEERING
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Immunomodulatory hybrid micro-nanofiber scaffolds enhance vascular regeneration
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作者 Yuanjing Hu Deling Kong +2 位作者 Xianhao Dong Kai Wang Meifeng Zhu 《Bioactive Materials》 SCIE CSCD 2023年第3期464-482,共19页
The inertness of synthetic polymer materials and the insufficient mechanical strength of reprocessed decellu-larized extracellular matrix(dECM)limited their promotive efforts on tissue regeneration.Here,we prepared a ... The inertness of synthetic polymer materials and the insufficient mechanical strength of reprocessed decellu-larized extracellular matrix(dECM)limited their promotive efforts on tissue regeneration.Here,we prepared a hybrid scaffold composed of PCL microfibers and human placental extracellular matrix(pECM)nanofibers by co-electrospinning,which was grafted with heparin and further absorbed with IL-4.The hybrid scaffold with improved hemocompatibility firstly switched macrophages to anti-inflammatory phenotype(increased by 18.1%)and then promoted migration,NO production,tube formation of endothelial cells(ECs),and migration and maturation of vascular smooth muscle cells(VSMCs),and ECM deposition in vitro and in vivo.ECs coverage rate increased by 8.6%and the thickness of the smooth muscle layer was 1.8 times more than PCL grafts at 12 wks.Our study realized the complementary advantages of synthetic polymer materials and dECM materials,and opened intriguing perspectives for the design and construction of small-diameter vascular grafts(SDVGs)and immune-regulated materials for other tissue regeneration. 展开更多
关键词 hybrid scaffolds PCL microfiber Placental ECM nanofiber IMMUNOREGULATION Vascular regeneration
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Fabrication of glycidyl methacrylate-modified silk fibroin/poly(L-lactic acid-co-ε-caprolactone)-polyethylene glycol diacrylate hybrid 3D nanofibrous scaffolds for tissue engineering
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作者 Yongyong Fan Anlin Yin +5 位作者 Yunhuan Li Qi Gu Yan Zhou Junlong Zhou Ruibo Zhao Kuihua Zhang 《Frontiers of Materials Science》 SCIE CSCD 2023年第2期79-91,共13页
In order to provide a biomimetic natural extracellular matrix microenvironment with excellent mechanical capacity for tissue regeneration,a novel porous hybrid glycidyl methacrylate-modified silk fibroin/poly(L-lactic... In order to provide a biomimetic natural extracellular matrix microenvironment with excellent mechanical capacity for tissue regeneration,a novel porous hybrid glycidyl methacrylate-modified silk fibroin/poly(L-lactic acid-co-ε-caprolactone)–polyethylene glycol diacrylate(SFMA/P(LLA-CL)–PEGDA)hybrid three-dimensional(3D)nanofibrous scaffolds was successfully fabricated through the combination of 3D nanofibrous platforms and divinyl PEGDA based photocrosslinking,and then further improved water resistance by ethanol vapor post-treatment.Scanning electron microscopy and micro-computed tomography results demonstrated significant PEGDA hydrogel-like matrices bonded nanofibers,which formed a 3D structure similar to that of“steel bar(nanofibers)‒cement(PEGDA)”,with proper pore size,high porosity,and high pore connectivity density.Meanwhile,the hybrid 3D nanofibrous scaffolds showed outstanding swelling properties as well as improved compressive and tensile properties.Furthermore,these hybrid 3D nanofibrous scaffolds could provide a biocompatible microenvironment,capable of inducing the material‒cell hybrid and regulating human umbilical vein endothelial cells proliferation.They thus present significant potential in tissue regeneration. 展开更多
关键词 hybrid 3D nanofibrous scaffold silk fibroin tissue engineering human umbilical vein endothelial cell
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新型乳酸-羟基乙酸共聚物(PLGA)/胶原复合材料用于软骨再生的体外研究 被引量:1
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作者 戴文达 张弛 +2 位作者 陈国平 姚振均 董健 《复旦学报(医学版)》 CAS CSCD 北大核心 2012年第4期335-341,共7页
目的设计和制备新型乳酸-羟基乙酸共聚物[poly(lactic-co-glycolic acid),PLGA]/胶原(collagen)复合材料,研究其在体外对软骨再生的促进作用,为软骨组织工程提供新型支架材料。方法利用冷冻干燥技术将胶原多孔海绵复合于PLGA编织网膜;... 目的设计和制备新型乳酸-羟基乙酸共聚物[poly(lactic-co-glycolic acid),PLGA]/胶原(collagen)复合材料,研究其在体外对软骨再生的促进作用,为软骨组织工程提供新型支架材料。方法利用冷冻干燥技术将胶原多孔海绵复合于PLGA编织网膜;扫描电镜观察材料表面微观结构,利用图像软件统计孔径大小;分离与培养牛膝关节软骨细胞(bovine articular chondrocyte,BAC),接种于PLGA/胶原材料,检测细胞接种效率,扫描电镜观察细胞在材料内部生长情况;体外培养1周后检测DNA和糖胺聚糖(glycosaminoglycan,GAG)含量,real-time PCR检测I型胶原、Ⅱ型胶原和聚集蛋白聚糖(aggrecan)mRNA表达强度。牛膝关节软骨组织和体外单层培养的BACs做对照。结果成功构建新型PLGA/胶原复合材料,表面孔径为(136.4±11.8)μm;细胞接种效率为87.8%±1.6%;BACs在材料表面和中心生长活跃,培养1周后的DNA、GAG含量,Ⅱ型胶原和聚集蛋白聚糖mRNA表达强度均显著高于对照组(P<0.05)。结论新设计制备的PLGA/胶原复合材料能促进体外软骨再生,可作为支架材料用于软骨组织工程研究。 展开更多
关键词 乳酸-羟基乙酸共聚物(PLGA) 胶原 复合材料 软骨再生
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适体家族新成员--肽适体 被引量:1
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作者 江丽 兰小鹏 《中国生物化学与分子生物学报》 CAS CSCD 北大核心 2009年第2期99-103,共5页
肽适体是一种从随机氨基酸的肽文库中筛选出来,可以高亲合力地与靶物质特异性结合的短肽序列.它的主要结构包括恒定的展示支架蛋白及通过两端限制性插入的高变肽环.酵母双杂交技术常用于筛选针对细胞内特异性靶蛋白的肽适体过程,筛选出... 肽适体是一种从随机氨基酸的肽文库中筛选出来,可以高亲合力地与靶物质特异性结合的短肽序列.它的主要结构包括恒定的展示支架蛋白及通过两端限制性插入的高变肽环.酵母双杂交技术常用于筛选针对细胞内特异性靶蛋白的肽适体过程,筛选出的肽适体通过特异性结合识别靶标发挥类似"干扰基因"的作用从而影响蛋白的生物学活性. 展开更多
关键词 肽适体 酵母双杂交 支架蛋白 干扰基因
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聚乳酸/钙磷盐/胶原骨组织工程支架混杂结构的研究 被引量:3
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作者 张人佶 王笠 +1 位作者 熊卓 颜永年 《山东生物医学工程》 2002年第3期1-4,共4页
首先采用碱式反应法和共混法获得两种胶原 /钙磷盐复合材料 ,然后通过真空吸附法在聚乳酸 /磷酸三钙的骨组织工程支架表面沉积胶原 ,又通过碱式反应法沉积钙磷盐 ,从而获得了具有混杂结构的支架。对材料形态的观察表明 ,胶原贴附在孔隙... 首先采用碱式反应法和共混法获得两种胶原 /钙磷盐复合材料 ,然后通过真空吸附法在聚乳酸 /磷酸三钙的骨组织工程支架表面沉积胶原 ,又通过碱式反应法沉积钙磷盐 ,从而获得了具有混杂结构的支架。对材料形态的观察表明 ,胶原贴附在孔隙中 ,钙磷盐沉积在胶原上。 展开更多
关键词 聚乳酸 PLA 钙磷盐 胶原 骨组织工程支架 混杂结构
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支架理论视角下高职院校混合式学习实践探索——以《电子商务实务》课程为例 被引量:1
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作者 陈思聪 《教育教学论坛》 2020年第10期230-231,共2页
快速发展的信息技术催生传统教学方法的变革,混合式学习的发展大大增加了教与学的多样性。文章尝试以支架理论作为方法论框架构建电子商务课程混合式学习模型,对混合式学习的理念进行了探讨,着重分析了教师在混合式学习不同阶段需要设... 快速发展的信息技术催生传统教学方法的变革,混合式学习的发展大大增加了教与学的多样性。文章尝试以支架理论作为方法论框架构建电子商务课程混合式学习模型,对混合式学习的理念进行了探讨,着重分析了教师在混合式学习不同阶段需要设计的学习支架,并通过高职《电子商务实务》课程进行验证。以期为混合式学习和混合式学习设计提供理论和实践参考。 展开更多
关键词 混合式学习 支架理论 《电子商务实务》
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榕江大桥矮塔斜拉桥次边跨施工方案比较 被引量:5
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作者 李传习 郑亮亮 +1 位作者 张玉平 谭立心 《世界桥梁》 北大核心 2015年第2期34-39,共6页
结合混合梁矮塔斜拉桥——榕江大桥工程实例,针对其70m次边跨钢箱梁,拟定了桥面吊机悬拼法(方案1)和支架法拼装(方案2)2种施工方案,分析2种方案在施工阶段受力安全性、经济性、施工控制难易性方面优缺点;建立了2种施工方案的全桥施工过... 结合混合梁矮塔斜拉桥——榕江大桥工程实例,针对其70m次边跨钢箱梁,拟定了桥面吊机悬拼法(方案1)和支架法拼装(方案2)2种施工方案,分析2种方案在施工阶段受力安全性、经济性、施工控制难易性方面优缺点;建立了2种施工方案的全桥施工过程有限元分析模型,对主要施工控制指标进行计算。特点分析和计算结果表明:2种施工方案结构应力均在允许范围,技术上均可行;在施工阶段结构安全性方面,方案2中结构应力较方案1有利,其边跨和次边跨提前完成为主跨单悬臂悬拼施工钢箱梁提供良好的锚固和压重作用;在施工经济性方面,方案2中钢材和小型吊机投入量较方案1多,但方案1中次边跨桥面吊机利用率低,其成桥后需第二轮调索,两者综合成本相差不大;在施工控制难易性方面,方案2中次边跨主梁线形控制较方案1容易且精度高,但两方案主跨主梁累计位移差别较大,应在确定钢箱梁安装线形前明确施工方案。 展开更多
关键词 矮塔斜拉桥 混合梁 钢箱梁施工 悬拼法 支架法 比较分析
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明胶杂化三维聚乳酸支架研究
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作者 张永红 陈际达 安身平 《组织工程与重建外科杂志》 2005年第5期283-286,共4页
目的克服聚乳酸材料的疏水性,制备表面特性和孔隙结构均符合组织工程需要的细胞支架。方法应用改进的溶液浇注/粒子沥滤技术,制备孔隙完全连通的三维聚乳酸细胞支架,碱液预处理支架表面,浸润明胶溶液,戊二醛蒸汽交联支架上的明胶,获得... 目的克服聚乳酸材料的疏水性,制备表面特性和孔隙结构均符合组织工程需要的细胞支架。方法应用改进的溶液浇注/粒子沥滤技术,制备孔隙完全连通的三维聚乳酸细胞支架,碱液预处理支架表面,浸润明胶溶液,戊二醛蒸汽交联支架上的明胶,获得杂化改性支架;用扫描电镜等对改性后的支架进行结构与性能表征。结果圆柱形多孔聚乳酸支架,在杂化改性后吸水率增加约2倍,由改性前的(1164.2±172.9)%上升到(2637.7±527.8)%,亲水性显著增强;杂化改性后,明胶均匀分布在支架孔隙表面,支架孔隙形态、连通性基本没有变化。结论明胶杂化能显著提高聚乳酸细胞支架的亲水性,改性过程不影响支架的孔隙结构和形态,可以制备出亲水性好、内部结构可控、孔隙率高、孔隙连通性好的组织工程细胞支架。 展开更多
关键词 三维细胞支架 明胶 杂化改性 亲水性 孔隙连通
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生物来源水凝胶在膀胱组织工程中的研究进展 被引量:3
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作者 安子彦 肖树伟 +1 位作者 符伟军 张旭 《解放军医学院学报》 CAS 北大核心 2021年第2期220-223,共4页
膀胱的修复重建一直是泌尿外科的重点研究方向,近年来随着组织工程技术的不断进步,这一问题有望从根本上得到解决。作为组织工程中最常用的支架材料之一,生物来源水凝胶可以模仿天然组织的结构,为细胞提供理想的生存环境和机械支持,其... 膀胱的修复重建一直是泌尿外科的重点研究方向,近年来随着组织工程技术的不断进步,这一问题有望从根本上得到解决。作为组织工程中最常用的支架材料之一,生物来源水凝胶可以模仿天然组织的结构,为细胞提供理想的生存环境和机械支持,其具备良好的生物相容性、可降解性和可塑性等,在膀胱组织工程中有广阔的应用前景。本文将对各种生物来源水凝胶材料进行介绍,并综述其在膀胱组织工程中的研究进展。 展开更多
关键词 膀胱组织工程 水凝胶 生物材料 混合支架 3D生物打印
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杂化小直径血管组织工程支架基材的共混改性与相容性分析 被引量:1
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作者 赵富强 陈俊英 +2 位作者 夏传俊 李天聪 黄霞 《化工新型材料》 CAS CSCD 北大核心 2019年第5期77-80,84,共5页
在杂化基材的前驱体(PA)中分别引入低分子量的聚乙二醇(PEG)和多壁碳纳米管(MWCNT),通过溶胶-凝胶共混法制备了2组复合组织工程支架基材,有机改性体系PEG/PA和添加了MWCNT的无机改性体系C/PA。并对改性体系的微观结构、热稳定性、溶胀... 在杂化基材的前驱体(PA)中分别引入低分子量的聚乙二醇(PEG)和多壁碳纳米管(MWCNT),通过溶胶-凝胶共混法制备了2组复合组织工程支架基材,有机改性体系PEG/PA和添加了MWCNT的无机改性体系C/PA。并对改性体系的微观结构、热稳定性、溶胀性能以及引入组分与基材的相容性进行了研究,比较了改性体系对脐静脉内皮细胞(HUVEC)形态和粘附行为的影响。制得的C/PA,在去离子水中的溶胀率为15.1%;在pH=7.4的PBS溶液中的溶胀率为16.8%,热稳定性较好,表面硬度适于细胞增殖分布,具有较好的应用前景。 展开更多
关键词 血管组织工程支架 共混改性 溶胶-凝胶法 细胞相容性
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High-precision,gelatin-based,hybrid,bilayer scaffolds using melt electro-writing to repair cartilage injury 被引量:2
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作者 Yu Han Bo Jia +5 位作者 Meifei Lian Binbin Sun Qiang Wu Benlin Sun Zhiguang Qiao Kerong Dai 《Bioactive Materials》 SCIE 2021年第7期2173-2186,共14页
Articular cartilage injury is a common disease in the field of orthopedics.Because cartilage has poor self-repairing ability,medical intervention is needed.Using melt electro-writing(MEW)technology,tissue engineering ... Articular cartilage injury is a common disease in the field of orthopedics.Because cartilage has poor self-repairing ability,medical intervention is needed.Using melt electro-writing(MEW)technology,tissue engineering scaffolds with high porosity and high precision can be prepared.However,ordinary materials,especially natural polymer materials,are difficult to print.In this study,gelatin was mixed with poly(lactic-co-glycolic acid)to prepare high-concentration and high-viscosity printer ink,which had good printability and formability.A composite scaffold with full-layer TGF-β1 loading mixed with hydroxyapatite was prepared,and the scaffold was implanted at the cartilage injury site;microfracture surgery was conducted to induce the mesenchyme in the bone marrow.Quality stem cells thereby promoted the repair of damaged cartilage.In summary,this study developed a novel printing method,explored the molding conditions based on MEW printing ink,and constructed a bioactive cartilage repair scaffold.The scaffold can use autologous bone marrow mesenchymal stem cells and induce their differentiation to promote cartilage repair. 展开更多
关键词 Gelatin-based hybrid bilayer scaffolds Melt electro-writing Cartilage injury Bone marrow mesenchymal stem cells
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强涌浪海域混合梁刚构桥钢箱梁顶推合龙技术 被引量:22
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作者 李宁 林树奎 秦明强 《桥梁建设》 EI CSCD 北大核心 2020年第4期118-123,共6页
援马尔代夫中马友谊大桥主桥为(100+2×180+140+100+60)m混合梁V形支腿连续刚构桥,180 m跨和140 m跨跨中区段主梁采用钢箱-超高性能混凝土叠合梁(每段叠合梁两端各包含长4.0 m的钢-混结合段),其跨中分别设置50 m和22 m长的钢箱梁合... 援马尔代夫中马友谊大桥主桥为(100+2×180+140+100+60)m混合梁V形支腿连续刚构桥,180 m跨和140 m跨跨中区段主梁采用钢箱-超高性能混凝土叠合梁(每段叠合梁两端各包含长4.0 m的钢-混结合段),其跨中分别设置50 m和22 m长的钢箱梁合龙段。因施工海域长周期波涌浪强烈,该桥大节段钢箱梁采用顶推合龙方案施工。在起吊钢-混结合段钢壳时,采用自动脱空的铰支架机构,以防止其碰撞甲板;在吊装小节段钢箱梁(50 m长的钢箱梁合龙段分为4个小节段)至混凝土箱梁顶时,采用横向油气弹簧+竖向橡胶支垫的落梁缓冲技术,以防止钢箱梁下落时与混凝土梁体碰撞;顶推时,通过支点反力和导梁应力双控来保证结构安全,并通过调整混凝土梁顶部压重来控制主墩平衡弯矩;钢箱梁采用横向错位工艺合龙,实现了高精度配切合龙。 展开更多
关键词 刚构桥 混合梁 钢箱梁 顶推施工 铰支架机构 落梁缓冲技术 横向错位合龙工艺 施工技术
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利用工业园区酒糟固废制备复合缓释碳源及其性能评估
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作者 李亚南 何友文 +3 位作者 刘遇瑶 王元月 佟娟 魏源送 《环境工程学报》 CAS CSCD 北大核心 2024年第3期696-708,共13页
我国工业园区污水厂进水碳氮比(C/N)普遍较低,常需补充碳源以提高脱氮效果。酒糟富含蛋白质、碳水化合物等有机组分,可生物利用性好,但目前缺乏其作为缓释碳源的研究。本研究以工业园区酒糟固废为原材料,以聚乙烯醇(PVA)、海藻酸钠(SA)... 我国工业园区污水厂进水碳氮比(C/N)普遍较低,常需补充碳源以提高脱氮效果。酒糟富含蛋白质、碳水化合物等有机组分,可生物利用性好,但目前缺乏其作为缓释碳源的研究。本研究以工业园区酒糟固废为原材料,以聚乙烯醇(PVA)、海藻酸钠(SA)为骨架材料,利用低温冷冻化学交联法制备复合缓释碳源,并进行释碳性能和反硝化性能评估。结果表明:通过骨架材料配比以及乳化剂优化研究,缓释碳源的快速释放期可延长到3 d,此阶段释碳过程为骨架溶蚀机制,单位质量缓释碳源的累积释碳量(以化学需氧量,即COD计)可达到1089 mg·(g·L)^(-1)。在酒糟用量为10 g·L^(-1),骨架材料配比为PVA:SA=8:1,乳化剂为1.0%span80条件下制备的缓释碳源在投加量为0.19 g·L^(-1),初始硝态氮(NO_(3)^(-)-N)为(41.53±0.1)mg·L^(-1)时,反硝化出水溶解性有机物(DOM)的腐殖化程度最低、分子质量最小、芳香环取代基种类和取代基程度最低,总氮去除率为99.2%,反硝化速率达到4.08 mg·(L·h)^(-1),为最佳缓释碳源。本研究结果可为工业园区的污水-固废协同治理提供参考。 展开更多
关键词 缓释碳源 骨架材料 酒糟 释碳机制 反硝化
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枝化状聚乙二醇交联去细胞瓣复合材料抗钙化性能研究 被引量:1
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作者 胡行健 邹明晖 +3 位作者 邓诚 史峰 史嘉玮 董念国 《中华实验外科杂志》 CAS CSCD 北大核心 2012年第11期2237-2239,共3页
目的探讨枝化状聚乙二醇(PEG)交联去细胞瓣复合材料的皮下抗钙化性能。方法N-丁二酸-S-乙酰基巯基乙二醇酯(SATA)巯基化修饰去细胞瓣,以相对分子质量为20×10^3的枝化状丙烯酰化PEG交联获得复合材料(PEG组)。以戊二醛固定天... 目的探讨枝化状聚乙二醇(PEG)交联去细胞瓣复合材料的皮下抗钙化性能。方法N-丁二酸-S-乙酰基巯基乙二醇酯(SATA)巯基化修饰去细胞瓣,以相对分子质量为20×10^3的枝化状丙烯酰化PEG交联获得复合材料(PEG组)。以戊二醛固定天然瓣(GA-NAV组)和戊二醛固定去细胞瓣(GA-DAV组)为对照。取3组瓣膜样本各18枚,植入新西兰白兔背部皮下,分别于2、4、8周取出行VonKossa染色观察钙沉积,原子吸收光谱法测定其钙含量。结果GA-NAV组钙化发生快且进展迅速,2、4、8周的钙含量依次为(22.39±1.79)、(93.05±6.08)、(174.97±8.34)μg/mg,GA-DAV组钙化程度较轻,钙含量分别为(5.57±2.11)、(31.15±5.16)、(72.54±6.50)μg/mg,而PEG组未见明显钙化发生,对应钙含量仅为(0.46±0.07)、(1.68±0.10)、(2.92±0.25)μg/mg,相同时间点组间差异有统计学意义(P〈0.05)。结论相对分子质量为20×10^3的枝化状丙烯酰化PEG交联去细胞瓣复合材料具有良好的抗钙化性能。 展开更多
关键词 去细胞瓣 聚乙二醇 复合支架
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建构主义视角下高校线上线下混合式教学的理论与实践探索 被引量:6
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作者 宋官东 肖彬 《高等农业教育》 2021年第4期72-77,共6页
建构主义主张意义建构在学生学习中的积极作用,重视学生新旧知识之间的联结,强调学生已有知识对新知识的主动加工与接纳。高校混合式教学的研究表明,建构主义混合式教学的关键是科学的教学设计,其中,教师教学情境的设计是激发学生学习... 建构主义主张意义建构在学生学习中的积极作用,重视学生新旧知识之间的联结,强调学生已有知识对新知识的主动加工与接纳。高校混合式教学的研究表明,建构主义混合式教学的关键是科学的教学设计,其中,教师教学情境的设计是激发学生学习动机、建立新旧知识关系的基础,能够为学生独立探索和协作学习提供内驱力,而教学评价则是考察学生学习效果的重要保证。学生对教学效果评价证明,基于建构主义的混合式教学能够保证学生学习的主体地位,有利于学生知识的掌握和智慧的提高,是一种十分有效的教学策略。 展开更多
关键词 建构主义 线上线下 混合式教学 支架式教学
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