天然聚合物电子纺纳米纤维的研究

对天然聚合物蚕丝、甲壳素、壳聚糖、明胶、蜘蛛丝、纤维素的电子纺制备纳米纤维的工艺条件及纤维结构进行综述。     

同轴纳米电缆研究进展

同轴纳米电缆是一维纳米材料家族中的一颗新星,在众多高精尖端技术领域具有十分诱人的应用前景.详细总结了近年来同轴纳米电缆的研究成果,全面归纳了其制备方法和研究现状.把制备方法概括为5类,即模板法、碳热还原与蒸发-凝聚法、溶胶-凝胶法、激光烧蚀法和化学气相沉积法.并展望了其发展趋势和应用前景.     

Electrospun scaffolds with surfaces modified by plasma for regeneration of articular cartilage tissue: a pilot study in rabbit

Abstract

This paper focuses on the development of an electrospun scaffold for application in cartilage regenerative engineering. Based on polylactic acid and polycaprolactone, the surface was modified with plasma polymerized polypyrrole-Iodine (PPy-I), which aims to improve cellular interaction and to ease the adhesion of the protein aggrecan (AG), an important component of the extracellular matrix of native cartilage. In vitro tests with autologous chondrocytes cells of rabbit were performed, and in vivo tests were performed over 30 days. Morphological and chemical characterizations of the scaffolds were executed. A comparison of the neotissue was done through tensile tests, histology and immunohistochemistry.     

Tailoring the morphology and crystallinity of poly(L-lactide acid) electrospun membranes

Abstract

Biodegradable poly(L-lactic acid) (PLLA) microfibers were prepared by electrospinning by varying the applied potential, solution flow rate and collector conditions. PLLA fibers with smoothly oriented and random morphologies were obtained and characterized by scanning electron microscopy. The optimum fiber orientation was obtained at 1000 rpm using a 20.3 cm diameter collecting drum, while for higher and lower drum rotation speeds, the rapid random motion of the jets resulted in a random fiber distribution. The deformation of the jet with rapid solidification during electrospinning often results in a metastable phase. PLLA electrospun fibers are amorphous but contain numerous crystal nuclei that rapidly grow when the sample is heated to 70–140 °C. In this way, the degree of crystallinity of the fibers can be tailored between 0 and 50% by annealing. Infrared transmission spectra revealed that the processing conditions do not affect the PLLA samples at the molecular level and that the crystallinity of the samples is related to the presence of α-crystals.     

滤波器耦合槽直径对其性能的影响仿真

采用高频结构模拟软件模拟1／4λ同轴型带通微波陶瓷滤波器结构,讨论了耦合槽直径对滤波器的性能如带宽、插损、带内波动、阻带抑制等的影响。结果表明,随着耦合槽直径的增大,滤波器中心频率、插入损耗和阻带抑制减小,3dB带宽增大。讨论结果表明,可通过调整滤波器耦合槽直径的大小,得到理想性能的介质滤波器。     

多芯同轴射频电缆的设计与制造

阐述了多芯同轴电缆的设计和制造工艺,特别对制造工艺对电缆阻抗均匀性的影响进行了分析,并提出了改进的措施.     

ZrO2-13%Al2O3陶瓷薄壁件激光近净成形实验

采用同轴送粉激光近净成形系统,在纯钛基体上进行激光近净成形(LENS)ZrO2-13%Al2O3(质量分数)复合陶瓷的基础实验研究。分析了激光功率和扫描速度对激光近净成形陶瓷薄壁宏观质量(宽高、表面平整性和宏观裂纹)的影响规律,获得致密、无宏观裂纹的陶瓷薄壁件。利用扫描电镜观察了成形件的微观组织,结合电子探针(EPMA)和X射线衍射仪(XRD)分析了微观组织成分和ZrO2陶瓷激光加工前后相成分的变化。结果表明,激光功率和扫描速度对激光近净成形陶瓷单层高度和表面宏观质量具有重要影响,通过精确控制该两个参数能够获得良好的表面质量;不同的激光功率和扫描速度下,会产生横向和纵向两种不同的宏观裂纹;激光近净成形技术能够制备出致密并具有细小枝状晶组织的陶瓷;少量的Al2O3主要存在于晶界中,有利于抑制裂纹扩展。     

75Ω电缆信号衰减建模探讨

在做卫星广播（广义）接收与有线电视网络等广电工程项目设计时,进行75Ω同轴电缆对所传输信号衰减值的理论计算是关键环节之一。利用在一定环境温度下通过实测得到的大量数据及统计、建模与仿真等方法,得到了国产物理发泡型75Ω同轴电缆衰减系数广电工程中常用计算公式的更适于工程设计理论计算的改进式βE=β（f,t）。     

新型红外地平敏感器非共轴红外光学系统的优化设计

从卫星用新型红外地平敏感器的视场设计出发,分析了光学膜厚度和锗红外光学材料的吸收对光学设计的影响,介绍了非共轴红外光学系统优化设计的方法,给出了其设计结果.试验表明,设计的非共轴红外光学系统完全满足卫星用新型红外地平敏感器的要求.