Preparation and properties of calcium sulfate bone cement incorporated with silk fibroin and Sema3A-loaded chitosan microspheres

To search for new bioactive materials which can be used as the substitute of bone repairing and drug carriers, Sema3A-loaded chitosan microspheres (SLCM) and silk fibroin (SF) were mixed with calcium sulfate cement (CSC). SEM, particle size analysis and swelling rate determination were performed to study properties of the microspheres. The drug loading, encapsulation efficiency and drug release rate were determined by ELISA. Microspheres with different SLCM weight contents (0.5%, 1% and 5%) were prepared to determine which one has the strongest mechanical properties and the appropriate setting time. It was revealed that CSC/SF/0.5SLCM has satisfactory mechanical properties, and its in vitro biocompatibility was assessed by MTS. Chitosan microspheres (5--18 μm) were globular, the surface was smooth, and the swelling rate is (77.02±5.57)%. With this formula, the setting time was increased with the addition of SLCM in CSC/SF, and the cumulative drug release rate is 44.62% in 28 d. XRD results demonstrate that the main component is calcium sulfate. Also it was found that CSC/SF/0.5SLCM supports the growth of MC3T3 cells. Thus the preparation of CSC/SF/0.5SLCM was reliable, and the products had good structures, physical properties and biocompati-bility, appearing to be a promising bone substitute material.     

多媒体多播组播单频网中免干扰动态信道分配

为了避免多媒体多播组播单频网(MBSFN)区域内部和区域之间的干扰,进一步提高频谱效率,该文提出一种改进的基于噪声调节时滞噪声混沌神经网络(NHNCNN)的动态信道分配方法。首先,根据MBSFN区域的特殊拓扑结构,重新定义了4种电磁兼容限制函数,在此基础上精心构建了免干扰的NHNCNN能量函数。其次对NHNCNN的稳态判定进程加以改进以提高系统的收敛速度。特别地,采用类二分法联合NHNCNN去搜索最小信道分配总数。仿真结果表明,利用富足的NHNCNN时滞、噪声和混沌神经动力,所提算法能有效地搜索到合理解,并最终找到全局最优解,提高了频谱效率。与现有方法相比,所提算法能够实现更好的收敛速度和合理解率。     

长玻纤增强聚丙烯热塑性复合材料制备风光互补发电系统风能叶片的模具设计和注射成型

对长玻纤增强聚丙烯(LFT-PP)和短玻纤增强聚酰胺(SFT-PA6)的性能进行了测试与比较。常温时(23 ℃),悬臂梁缺口冲击强度前者比后者提高3.44 %,吸水率后者比前者高100 %,模收缩率前者比后者低10 %;低温时(-30 ℃),前者的冲击强度提高了16 %~24 %。通过优化的模具设计、模流数值计算分析和注塑工艺条件实验,选择最佳注塑工艺参数制备LFT-PP叶片,可使叶片疲劳断裂强度的最大静载荷测试值达到150 kg。     

基于水下多波束的长江堤防护岸工程监测技术研究

为了预防长江堤防护岸工程受损或者大面积崩岸的发生,应定期对护岸工程进行监测和稳定性分析,必要时采取工程措施消除安全隐患。根据水下多波束测深技术全覆盖、高精度、高效率等特点,探讨了水下多波束测深系统的平面位置和水深测量精度,论述了基于水下多波束的护岸工程监测技术方法。并以湖北省监利县铺子湾护岸工程为例,采用水下多波束测深技术,连续2 a同一时段进行全覆盖扫测,根据2次扫测结果,采用3种不同的分析方法对堤防护岸工程地形变化进行分析。结果表明：护岸工程实施后深槽向右岸偏移,岸坡冲淤平衡,护岸工程稳定。     

特高压交流输电线路复合绝缘子和均压环场强影响因素

1 000 kV特高压交流输电线路复合绝缘子和均压环表面电场分布数值仿真研究具有媒质种类多、几何结构复杂、计算量大等特点。为保证计算精度,需全面分析相关因素的影响,以合理简化计算模型,提高计算效率。通过建立特高压交流输电线路双联复合绝缘子的三维静电场有限元全模型和简化模型,研究了导线、杆塔、金具、联板等因素对复合绝缘子和均压环表面电场分布的影响,验证了模型简化的合理性。全模型和简化模型计算结果对比表明,将三相导线控制在一定长度,对杆塔合理简化、省略联板和金具的简化方法可行,用简化模型代替完整模型进行复合绝缘子电位分布、电场分布以及均压环表面电场分布的仿真研究,可有效降低计算规模,提高特高压交流输电线路绝缘子和均压环参数优化配置分析效率。     

FBG传感技术在矿山地压监测中的应用

在分析光纤Bragg光栅传感(FBG)原理的基础上,提出基于FBG的地压监测系统。在承德铜兴矿业有限责任公司建立该地压监测系统,实时监测岩体的位移和压力变化。监测结果表明,FBG传感技术可有效监测岩体位移和压力变化,可靠性和稳定性较好,具有广阔的应用前景。     

Precise Analytical Formulae of Spaceborne SAR＇s Doppler Parameters in Elliptical Orbits

Several precise analytical formulae for the calculation of Doppler parameters in elliptical orbits are derived. The motivation is that most of the existing results are only valid in nearly circular orbits and that the impact of fllght-path angle is neglected in the very few published papers which focus on the similar subject. The derivation is based on some existing formulae which are precise but hard-to-use. The deduction principle is to transform the existing formulae into the form we expected. In the deduction process, all impacts brought by the orbit＇s eccen- tricity are considered. Two simulation experiments were performed. One is for a traditional Earth-orbltlng SAR （Synthetic aperture radar） while the other is for a non- cooperative satellite with large eccentricity. The achieved results validate the correctness of the derived formulae and demonstrate the impact of the fllght-path angle on Doppler parameters for high eccentricity orbits.     

PVC/阻燃抑烟剂体系的力化学改性

研究了高能振磨作用对PVC／硼酸锌(ZB),PVC／三氧化二锑(Sb2O3)-三氧化钼(MoO3)以及PVC／Sb2O3-MoO3-ZB体系阻燃抑烟性能和力学性能的影响。结果表明,高能振磨可使PVC与ZB、Sb2O3或MoO3分子闯产生化学键合,增强了PVC基体与阻燃抑烟荆ZB,Sb2O3-MoO3,Sb2O3-MoO3-ZB之同的界面相互作用,促进了阻燃抑烟荆(FRs)在PVC中的分散,使PVC／FRs体系的烟密度(Dm)值降低,极限氧指数(LOI)值以及抗冲击强度,拉伸强度,断裂伸长率得到明显提高。     

恶意网页修改注册表的现象分析

分析了一些恶意网页修改注册表的现象,并提出了修改方法.     

铝型材用丙烯酸酯类阴极电泳涂料树脂的合成及应用

采用自由基溶液聚合方法,合成了可用于阴极电泳涂料的阳离子型丙烯酸树脂。研究了树脂的水溶性、交联度、分子量及其分布、玻璃化温度等的影响因素：结果表明,当共聚单体N-羟甲基丙烯酰胺(NMA)和甲基丙烯酸羟乙酯(HEMA)的质量分数分剐为6％和15％时,树脂的交联度较高;当共聚物中氨基单体的质量分数为12％～20％,羟基单体的质量分数为12％～15％时,控制中和度在75％～80％范围内,所得的树脂水溶性优良;以偶氮二异丁腈(AIBN)为主引发剂,以过氧化苯甲酸叔戊酯(TAPB)为辅助引发剂,控制聚合温度为85～95℃,单体滴加时间为3h,即可较好地调节树脂的相对分子量及其分布,且所得的树脂颜色较浅。对树脂在铝片上电泳涂装后之涂膜性能测试实验表明,当玻璃化温度在30～60℃时,所得树脂性能优良,其涂膜厚度为,10～15m,硬度达4～5H,耐冲击强度50kg／cm2,附着力为1级。