Atmospheric elemental concentration determined by Particle-Induced X-ray Emission at Tlaxcoapan in central Mexico, and its relation to Tula industrial-corridor emissions

The Tula-Vito-Apasco industrial corridor is considered one of the most contaminated zones in Mexico. In this corridor, at Hidalgo state, is located the Miguel Hidalgo refinery, the biggest in the country. Although ecology agencies monitor criterion contaminants in a routine basis, scarce data are available about elemental composition of particulate matter (PM). The PM₁₀ elemental composition of Tula vicinity is being analyzed and results of the field study performed in Tlaxcoapan, Hidalgo are presented here. This small agricultural town is located within a 7.5 km from Tula-Vito-Apasco industrial corridor. PM₁₀ fraction of atmospheric aerosols collected in filters from July to December 2007, was analyzed using Particle Induced X-ray Emission (PIXE) technique, and sixteen elements were detected. Temporal variations were observed during the studied period. Enrichment Factors were moderately high for S, Ca, V, Ni, Cu, Zn and Pb. Rain did not have strong influence but high amounts of sulfur were correlated to high amounts of Ni and V. Comparison of our results with other data from nearby allocations, shows good general agreement. A receptor model with principal component factor analysis (PCFA) and VARIMAX rotation was applied to data in order to estimate source apportionment. Four main sources were identified: soil that contributes to the elemental composition of filters with 26%, refinery and the power plant with 20% and two independent industrial emissions summed 26%. The last three polluting sources indicate that the industrial activities carried out in the corridor have a harmful impact in Tlaxcoapan, Hidalgo.     

Parametrization of Transfer Matrix： for One-Dimensional Anderson Model with Diagonal Disorder

In this paper, we developed a new parametrization method to calculate the localization length in onedimensional Anderson model with diagonal disorder. This method can avoid the divergence difficulty encountered in the conventional methods, and significantly save computing time as well.     

二维随机介质中柱面波传播及其局域性的随机泛函分析

分析了二维各向同性均匀随机介质中柱面波的传播特性及局域化现象.用随机泛函理论,在频域内将随机介电起伏展开成柱坐标系下的Wiener积分式,将波场表示为内外行柱面波的线性和,求解二维Helmholtz波动方程,得到随机介电起伏对柱面波幅度与相位调制的解析表达.由柱面波能量的空间分布验证了波的局域化现象,并求解局域化长度.二维随机介质中平面波按柱面波展开的波转换方程与非随机介质中的情形有相似的表达,但具有随机介电起伏对幅度和相位的调制,并给出数值模拟结果.     

Bending localization of nitrous oxide under anharmonicity and Fermi coupling: the dynamical potential approach

This paper studies the vibrational nonlinear dynamics of nitrous oxide with Fermi coupling between the symmetric stretching and bending coordinates by classical dynamical potential approach.This is a global approach in the sense that the overall dynamics is evidenced by the classical nonlinear variables such as the fixed points and the focus are on a set of levels instead of individual ones.The dynamics of nitrous oxide is demonstrated to be not so much dependent on the excitation energy.Moreover,the localized bending mode is shown to be ubiquitous in all the energy range studied.     

Piezonuclear neutrons from fracturing of inert solids

Neutron emission measurements by means of helium-3 neutron detectors were performed on solid test specimens during crushing failure. The materials used were marble and granite, selected in that they present a different behaviour in compression failure (i.e., a different brittleness index) and a different iron content. All the test specimens were of the same size and shape. Neutron emissions from the granite test specimens were found to be of about one order of magnitude higher than the natural background level at the time of failure. These neutron emissions should be caused by nucleolysis or piezonuclear “fissions” that occurred in the granite, but did not occur in the marble: . The present natural abundance of aluminum (7-8% in the Earth crust), which is less favoured than iron from a nuclear point of view, is possibly due to the above piezonuclear fission reaction. Despite the apparently low statistical relevance of the results presented in this Letter, it is useful to present them in order to give to other teams the possibility to repeat the experiment.     

Effect of Fabry‐Perot resonances in disordered one‐dimensional array of alternating dielectric bi‐layers

We study numerically and analytically the role of Fabry‐Perot resonances in the transmission through a one‐dimensional finite array formed by two alternating dielectric slabs. The disorder consists in varying randomly the width of one type of layers while keeping constant the width of the other type. Our numerical simulations show that localization is strongly inhibited in a wide neighborhood of the Fabry‐Perot resonances. Comparison of our numerical results with an analytical expression for the average transmission, derived for weak disorder and finite number of cells, reveals that such expression works well even for medium disorder up to a certain frequency. Our results are valid for photonic and phononic one‐dimensional disordered crystals, as well as for semiconductor superlattices.     

Purely electronic transport and localization in the Bose glass

We discuss transport and localization properties on the insulating side of the disorder dominated superconductor‐insulator transition, described in terms of the dirty boson model. Analyzing the spectral properties of the interacting bosons in the absence of phonons, we argue that the Bose glass phase admits three distinct regimes. For strongest disorder the boson system is a fully localized, perfect insulator at any temperature. At smaller disorder, only the low temperature phase exhibits perfect insulation while delocalization takes place above a finite temperature. We argue that a third phase must intervene between these perfect insulators and the superconductor. This conducting Bose glass phase is characterized by a mobility edge in the many body spectrum, located at finite energy above the ground state. In this insulating regime purely electronically activated transport occurs, with a conductivity following an Arrhenius law at asymptotically low temperatures, while a tendency to superactivation is predicted at higher T. These predictions are in good agreement with recent transport experiments in highly disordered films of superconducting materials.     

La_2Cu_(1-x)V_xO_(4+δ)(0≤x≤0.08)的晶体结构及电输运性质

本文研究了La2Cu1-xVxOv+δ(0≤x≤0.08)的结构及电输运性质.用Rietveld方法对所有样品的X射线衍射谱进行了拟合.结果表明,全部样品都具有正交对称性,晶胞参数随掺杂量的增加几乎没有变化.随着V掺杂量增加到0.08,而La2Cu1-xVxO4+δ中过量氧的平均值从0.006增加到0.007.没有掺杂的样品由于氧过量而存在相分离状态,体系中存在超导相与绝缘相的竞争相互作用.随着V掺杂量增加,超导相受到破坏,我们认为,V掺杂对超导电性抑制的原因可能是载流子浓度的减少和载流子的局域化所致.     

神经系统的简并性与序空间编码分析

Edelman提出了神经系统中存在简并现象,但并未说明简并在神经系统中的具体形式和作用.文中从序空间理论出发,以神经回路为讨论基础,具体讨论了双耳定向的神经回路中可能出现的简并网络,以及各种网络被简并的方法.把简并现象的讨论和编码的讨论结合起来,对神经网络中的简并现象有了一个具体的认识.文中虽然是由纯理论推导的结果,但所得回路包含了被广泛承认的Jeffress模型,因此也间接证明了该理论也有一定的生物学基础. 关键词： 简并 神经编码 序空间 双耳声源定向     

高效液相色谱法测定饮用水源水中吡啶

建立直接进水样高效液相色谱法测定饮用水源水中吡啶的分析方法。在优化的条件下,曲线浓度范围在0.01—2.0mg/L,吡啶的响应值与浓度有良好的线性关系,灵敏度高,最低检出质量浓度为0.004mg/L。该方法还具有预处理简便、不使用剧毒试剂、分析速度快等优点。相对标准偏差不大于6.4%（n=7）,回收率为88%—106%。实验证明,该方法符合国标GB3838-2002的要求,与推荐方法相比具有操作简便快速、环保安全等优点。