320排CT低碘浓度联合低管电压在冠脉成像中的应用研究

目的探讨320排螺旋CT低管电压技术联合低碘浓度在冠状动脉成像中的可行性.方法将40例疑似冠心病患者随机分为两组,使用东芝320排螺旋CT进行冠状动脉扫描,分别对两组图像质量进行主观和客观评分,对比有效辐射剂量及碘摄取量.结果 A,B两组的有效辐射剂量及碘摄入量比较差异具有统计学意义(P0.05),B组患者有效辐射剂量低于A组,且有效辐射剂量较A组降低72.95%,B组患者有效碘摄入量较A组减少18.29%,两组图像噪声值、左冠脉开口处强化CT值差异具有统计学意义(P0.05),B组图像噪声高于A组,两组图像质量主观评分比较差异无统计学意义(P0.05).结论 320排螺旋CT冠状动脉成像采用"双低"扫描方案能降低有效辐射剂量和碘摄入量.     

子宫腺肌病囊肿1例临床分析

目的 探讨子宫腺肌病囊肿临床表现、诊断、鉴别诊断及治疗.方法 根据患者病例报告,并查阅相关文献,进一步总结子宫腺肌病囊肿的临床特点.结果 子宫腺肌病囊肿是一类在子宫肌层的较大囊性病变,其内充满子宫内膜异位组织和血液,术中所见及术后病理可明确诊断.结论 子宫腺肌病囊肿的临床表现与子宫腺肌病相似,国内外报道极少,临床误诊率高,临床医生应提高对该病的认识.     

基于超声波的汽车防撞系统

在现有的汽车防撞系统中,主要都是使用雷达进行测距,这类系统的价格较高,不能大面积推广.在现有的汽车防撞系统上优化测距算法,采用超声波传感器进行测距,建立相关的防撞模型,根据不同的测量距离发出不同的报警信息.实验结果表明,在一定范围内报警信息准确.     

有失效等待的二元预防维修策略

在系统失效不能立即被处理、须等到下次预防维修时刻才能被处理的前提下,研究了一类依赖于临界可靠度R和预防维修次数阀值N的二元预防维修策略.利用相关原理,得出了各种可靠性指标,并建立了系统平均费用关于R和N的函数表达式.同时,利用图像搜索法得出了一实际数值例子的最优维修策略,在此最优策略下系统单位时间平均费用最小.     

明代夯土长城的城墙材料与构造——以大同镇段为例

为了深入了解夯土长城的材料和构造特征,在对现存明大同镇段长城这一典型夯土长城遗存进行实地考察的基础上,借鉴土力学的相关理论和方法,对城墙夯土材料的种类和存在方式进行了分类统计,并从基础做法、夯层厚度、夯层构造和铺设植物枝条做法等方面分析了城墙的构造特征,揭示出夯土长城在材料和构造方面的丰富性以及与环境的密切相关性.结果表明,明大同镇段夯土长城的城墙高度一般为6~10 m,墙面斜度一般为70°~80°,夯层厚度多为150~250 mm,夯土材料由细粒土、砂砾、碎石、块石和植物枝条组成,夯土材料中砂砾、碎石和块石的含量与地形和土壤环境有密切关系,证明取材方式为就近取土,夯层中砂砾、碎石和块石或铺砌或掺杂的多种构造方式反映了古人基于当地土质和实践经验对夯层构造的改良,少数案例显示了夯土中可能铺设了植物枝条作为连接筋,反映了古人的夯土技术成就.     

牛蒡子饮片和牛蒡子现代饮片RP-HPLC指纹图谱对比研究

通过对比分析牛蒡子饮片及牛蒡子现代饮片指纹图谱,探讨两者之间品质是否存在差异.采用RP-HPLC指纹图谱技术,对牛蒡子饮片及牛蒡子现代饮片进行指纹图谱研究,并建立共有模式,同时,采用“中药色谱指纹图谱相似度评价系统”对所得图谱进行相似度分析.结果表明:牛蒡子饮片和牛蒡子现代饮片所测定的色谱图中,指纹图谱共有峰均有7个,...     

Effect of Dy3+on osteogenic and adipogenic differentiation of mouse primary bone marrow stromal cells and adipocytic trans-differentiation of mouse primary osteoblasts

A series of experimental methods including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test, alkaline phosphatase (ALP) activity measurement, mineralized function, Oil Red O stain and measurement were employed to assess the effect of Dy³⁺ on the osteogenic and adipogenic differentiation of mouse primary bone marrow stromal cells (BMSCs) and the adipogenic trans-differentiation of mouse primary osteoblasts (OBs). The results showed that Dy³⁺ had no effect on BMSC proliferation at concentrations of 1×10⁻⁸ and 1×10⁻⁵ mol/L, but inhibited BMSC proliferation at other concentrations. Dy³⁺ had no effect on OB proliferation at concentrations of 1×10⁻¹⁰ and 1×10⁻⁹ mol/L, but inhibited OB proliferation at other concentrations. Dy³⁺ had no effect on the osteogenic differentiation of BMSCs at concentrations of 1×10⁻⁹ and 1×10⁻⁷ mol/L, and promoted osteogenic differentiation of BMSCs at other concentrations at the 7th day. The osteogenic differentiation of BMSCs was inhibited by Dy³⁺ at concentration of 1×10⁻⁵ mol/L at the 14th day, but promoted osteogenic differentiation of BMSCs at concentrations of 1×10⁻⁹, 1×10⁻⁸, 1×10⁻⁷ and 1×10⁻⁶ mol/L with the maximal effect at concentration of 10⁻⁶ mol/L. Dy³⁺ promoted mineralized function of BMSCs at any concentration. Dy³⁺ had no effect on adipogenic differentiation of BMSCs at concentration of 1×10⁻⁷ mol/L, but inhibited adipogenic differentiation of BMSCs at other concentrations. Dy³⁺ inhibited adipocytic trans-differentiation of OBs at any concentration, suggesting that Dy³⁺ had protective effect on bone and the protective effect on bone may be mediated by modulating differentiation of BMSCs away from the adipocyte and inhibiting adipocytic trans-differentiation of OBs which may promote differentiation and mineralization of OBs. These results may be valuable for better understanding the mechanism of the effect of Dy³⁺ on pathogenesis of osteoporosis. Supported by the Foundation for Key Program of Ministry of Education of China (Grant No. 208018)     

Bionic asymmetry: from amiiform fish to undulating robotic fins

Similar to bionic non-smooth which has been successfully applied in anti-resistance and anti-adhesion, bionic asymmetry is also an inherent property of biological systems and is worth exploring for conceivable pragmatic applications. Therefore, bionic asymmetry for undulations is of main interest in this paper. We initially investigate bionic asymmetry with a case study of the undulating robotic fin, RoboGnilos, which evolved from the long dorsal fin of Gymnarchus niloticus in the amiiform mode. Since the performance of the pre-existing undulating fins is hardly satisfactory, we obtain bionic inspirations of undulatory asymmetry through observations and measurements on the specimen of G. niloticus, to improve upon the performance. Consequently, the newly acquired innovation for bionic asymmetry is incorporated into the previously derived kinematics model, and also applied to the experimental prototype. Both computational and experimental results verify that bionic asymmetric undulation generates better propulsion performance (in terms of linear velocity and efficiency) than the traditional symmetric modes with the same undulatory parameters. Supported by the National Defense Fundamental Research Project of China (Grant No. D28200613) and National Natural Science Foundation of China (Grant No. 50405006)     

Genome-wide distribution of histone H3 acetylation in all- trans retinoic acid induced neuronal differentiation of SH-SY5Y cells

With chromatin immunoprecipitation (ChIP) and promoter DNA microarray analyses (ChIP-on-chip), we analyzed the variations of acetylation on histone H3 in all-trans retinoic acid (RA) induced neuronal cell differentiation. Neuroblastoma SH-SY5Y cells were treated with RA for 24 h and the acetylation on histone H3 in the promoter region of the genes was detected. Results showed that, after treatment, the level of acetylation on histone H3 elevated in 597 genes in the genome, and reduced in the other 647 genes compared with those of the control. In summary, we have successfully adopted a high throughput technique to detect and analyze variations of acetylation of histone H3 in human genome at the early phage of RA induced neuronal differentiation of the SH-SY5Y cells. Supported by National Natural Science Foundation of China (Grant Nos. 90408007 and 30721063) and National Key Basic Research and Development Program of China (Grant No. 2004CB518605)     

Synthesis and characterization of N-aryloxo-functiona- lized β-ketoiminate rare-earth complexes and their catalytic activity for the polymerization of ε-caprolactone

The synthesis and characterization of dimeric rare-earth amides stabilized by a dianionic N-aryloxo functionalized ,8-ketoiminate ligand are described. Reactions of 4-（2-hydroxy-5-methyl-phenyl） imino-2-pentanone （LH2） with Ln[N（SiMe3）2]3（μ-Cl）Li（THF）3 in a 1：1 molar ratio in THF gave the dimeric rare-earth amido complexes [LLn{N（SiMe3）2}（THF）]2 [Ln = Nd （1）, Sm （2）, Yb （3）, Y （4）]. These complexes were well characterized, and the definitive molecular structures of complexes 3 and 4 were determined. It was found that complexes 1-4 can initiate the ring-opening polymerization of ε-caprolactone, and the ionic radii of the central metals have significant effect on the catalytic activity.