Trace element concentrations in hair of healthy Chinese centenarians

Trace element concentrations, as indicators of micronutrient status of healthy centenarians, have not been widely analyzed. This study aimed to assess trace element concentrations in the hair of healthy centenarians. The effects of gender and age on element concentrations were also investigated. Eleven trace elements (Al, Ba, Cd, Cr, Cu, Fe, Mo, Pb, Se, Sr and Zn) in the scalp hair of 107 healthy Chinese centenarians were examined. The overall reference values (RVs) in mg/kg for the hair concentrations of trace elements in centenarians were as follows: Al, 14.95; Ba, 2.68; Cd, 0.06; Cr, 0.59; Cu, 6.21); Fe, 19.37; Mo, 0.50; Pb, 4.64; Se, 0.37; Sr, 4.84; and Zn, 154.37. Data analysis found that only Cu and Zn concentrations show a normal distribution, and there is no significant difference between males and females in any element except Zn. However, the levels of Al, Cd, Cr, Fe, Mo, Pb decrease and the levels of Ba, Cu, Se, Sr, Zn increase with age in the centenarian cohort. Results also revealed that sufficient Zn and Se concentrations as well as low exposure to heavy metals pollution contribute to the longevity of centenarians. The results imply the possibility of manipulating trace element concentrations, especially Zn and Se concentrations in tissues, as a means for therapeutic modality in geriatric disease.     

Real-time dynamic substructuring testing of viscous seismic protective devices for bridge structures

This paper presents a real-time dynamic substructuring (RTDS) test program carried out on bridge structures equipped with two innovative viscous seismic protective devices: a seismic damping unit and a shock transmission unit. In the RTDS tests, the seismic protective units were physically tested in the laboratory using a high performance dynamic actuator imposing, in real time, the displacement time histories obtained from numerical simulations being run in parallel. The integration scheme used in the test program was the Rosenbrock-W variant, and the integration was performed using The MathWorks’ Simulink and XPC target computer environment. The numerical counterpart included the bridge columns and the additional energy dissipation properties. The nonlinear response of these components was accounted for in the numerical models. The tests were run under various ground motions, and the influence of modeling assumptions such as damping and initial stiffness was investigated. Finally, the test results are compared to the predictions from nonlinear dynamic time history analyses performed using commercially available computer programs. The results indicate that simple numerical modeling techniques can lead to accurate prediction of the displacement response of bridge structures equipped with the seismic protective systems studied.     

A probabilistic approach for estimating the behavior of railway tracks

Railway engineering is confronted with problems due to degradation of the rail network that requires important and costly maintenance work. However, because of lack of knowledge on the geometrical and mechanical parameters of the track, it is difficult to optimize maintenance management. In this context, this paper presents a new methodology to analyze the behavior of railway tracks. It combines new diagnostic devices which permit to obtain an important amount of data and thus to make statistics on the geometric and mechanical parameters and a non-intrusive stochastic approach which can be coupled with any mechanical model. Numerical results show the possibilities of this methodology for parametric studies (influence of the distribution and of the correlation of the parameters...). In the future this approach will give important informations to railway managers to optimize maintenance operations.     

Seismic response of liquid-filled elevated tanks

The main focus of the current study is to evaluate the performance of elevated tanks under seismic loading. In this study, the finite element (FE) technique is used to investigate the seismic response of liquid-filled tanks. The fluid domain is modeled using displacement-based fluid elements. Both time history and modal analyses are performed on an elevated tank. Using the FE technique, impulsive and convective response components are obtained separately. Furthermore, the effect of tank wall flexibility and sloshing of the water free surface are accounted for in the FE analysis. In this study complexities associated with modeling of the conical shaped tanks are discussed. This study shows that the proposed finite element technique is capable of accounting for the fluid-structure interaction in liquid containing structures. Using this method, the study of liquid sloshing effects in tanks with complex geometries such as conical tanks is made possible. The results of this study show that the current practice predicts the response of elevated tanks with reasonable accuracy.     

织金含稀土白云质磷块岩物质组成及稀土元素特征

选择贵州织金新华戈仲伍地区含稀土白云质磷块岩为研究对象,研究其矿物组成、化学成分、微量元素、稀土元素等特征。矿石主要矿物为白云石、氟磷灰石、石英等。矿石P2O5平均含量20.18%,主要稀土为钇（Y2O3）、镧（La2O3）、钕（Nd2O3）、铈（CeO2）,占稀土总量的84.51%～85.50%。矿石中P2O5和稀土元素含量均随风化程度加深而增加。本研究为该矿的综合开发利用提供基础资料。     

多因素作用下钢筋混凝土构件氯离子扩散系数模型

通过对钢筋混凝土氯离子侵蚀机理的分析,在Fick第二扩散定律基础上,建立了综合考虑水灰比、湿度、时间、温度、混凝土材料对氯离子结合作用等多因素作用下的氯离子侵蚀模型,并给出了考虑边界条件的侵蚀模型数学解.通过对长期现场暴露试验数据分析,验证了该侵蚀模型的有效性和可靠性.与传统的Fick第二扩散定律模型对比并分析得:该模...     

地球化学元素分布特征分析在找矿中的应用——以江西省遂川县金坑金矿为例

以江西遂川金坑土壤化学采样为研究对象,对研究区内土壤中十种金属元素Au、Ag、As、Sb、Cu、Pb、Zn、W、Bi、Sn的化探数据进行了分析,运用概率统计分析,剔除特高、特低含量值,形成数据正态分布,运用MAPGIS的空间分析能力,圈定十种金属元素的异常范围,得到土壤中十种金属元素分布状况及其特征.通过主成分分析,减少了综合异常圈定的影响因素.结果发现Au、Ag、Cu、Pb、Zn等地球化学异常密集分布,这些发现将对进一步勘查提供有力的支持.     

现代小区景观的构成及艺术氛围生成机制

简要介绍了景观的概念,从构成元素和艺术氛围的生成机制两方面入手,探讨了现代小区景观设计手法,指出应综合考虑构成景观的各种元素,通过点、线、面、体的不同搭配并选取适当表现手法,促进居住区景观艺术氛围的生成。     

住宅小区景观设计中的乡土元素

在探讨乡土景观的概念和特性的基础上,提出了乡土元素在住宅小区中应用的重要原则和相关方法,并具体探讨了自然元素和文化元素在乡土景观设计中的应用,提出了乡土景观在现代住宅小区应用的意义。     

基于文件的矿图系统研究与实现

 就当前我国矿图绘制技术和方案中存在的问题和弊端,以图形数据冗余最小、要素表达一致、绘制精度一致、图形更新同步为目标,提出了基于文件的矿图绘制方案。对矿图要素的分类与分层表示、矿图文件的创建、图层控制与优化组合展开了研究,并实现了基于文件的矿图自动生成目标。