CHEMICAL AND TOXICOLOGICAL CHARACTERIZATION OF AIRBORNE TOTAL SUSPENDED PARTICULATE (TSP) AND PM 10 ORGANIC EXTRACTS

The relationship between chemical composition of airborne particulates and the genotoxicity has been investigated in the atmosphere of Rome, Italy. For this purpose, both total suspended particulate (TSP) and the PM ₁₀ fractions were collected daily inside a green park located in downtown, grouped on a weekly basis and speciated for their burdens of polycyclic aromatic hydrocarbons (PAH) and nitro-PAH. Concurrently, the genotoxicity of the organic extracts was evaluated by the Comet assay (SCGE: single cell gel electrophoresis) on human peripheral blood mononuclear cells (PBMC). The results indicate that organic extracts were able to induce DNA damage and a cytotoxic effect on PBMC. The TSP fraction was more cytotoxic than PM ₁₀ while the genotoxicity of both fractions was comparable. The genotoxic potential of the different samples was highly correlated to the amount of total PAH (correlation coefficient = 0.87), carcinogenic PAH (correlation coefficient = 0.88), B(a)P (correlation coefficient = 0.87) and to a less extend to the concentration of 1-nitropyrene (correlation coefficient = 0.66). The seasonal modulation suggests that in Rome the air is more toxic during winter, however in the warm season oxidized species including nitro-PAHs (evolving from secondary pollution) seem to balance the decrease of PAH concentration rates.     

Foster + Partners' Hearst Tower and Gehry Partners' IAC Building

The two most interesting, talked about new office buildings in New York both have unique angular profiles and unusual shiny surfaces that have irrevocably changed their neighbourhoods. Jayne Merkel takes a peak at the interiors of Norman Foster's triangulated steel-and-glass Hearst Tower and Frank Gehry's curvaceous, white-glass hulk for the IAC/InterActiveCorp. In so doing she sizes up what effect the exotic exteriors have on the spaces where the editors, writers, designers and media executives work. Copyright © 2007 John Wiley & Sons, Ltd.     

Extraction and recovery of cadmium(Ⅱ) using phosphine-oxide,tris[(dibutylamino)methyl]-(7CI,8CI) from nitric acid solutions

In the present article, a new separation system was employed for the extraction of cadmium from nitric acid solutions for the first time. Phosphine oxide, tris[(dibutylamino)methyl]-(7CI,8CI),which contains nitrogen atoms and phosphorus atom in molecular, was used as extractant. The influence of the following parameters was investigated: the organic/aqueous phase ratio (O/A), pH, contact time, temperature, the concentration of extractant, cadmium (Ⅱ), sodium nitrate and sodium chloride. Results demonstrated that quantitative extraction of cadmium was feasible from 50 mg/L cadmium feed solution in a single stage at pH 3.0, 15 min and O/A phase ratio 1:5 with 20% extractant in cyclohexane diluent. The cadmium extraction isotherm under different cadmium ion concentrations was established. The loaded cadmium could be stripped by 4 mol/L ammonium chloride aqueous solutions. A contrast study was carried out, and the results indicated that phosphine oxide, tris[(dibutylamino)methyl] –(7CI,8CI), could take the place of commercial organo-phosphorous extractants in the process of cadmium(II) extractions for its effectivity, stability and low price.     

轮状病毒P[2]G3株在人二倍体细胞KMB17上的适应性

目的探讨轮状病毒P[2]G3株在人二倍体细胞KMB17上的适应性。方法轮状病毒P[2]G3株在猴肾细胞MA104上经蚀斑筛选纯化后,得到的克隆以不同MOI接种至人二倍体细胞KMB17上。用微量滴定法与蚀斑法平行检测病毒滴度,用免疫荧光法检测病毒的增殖情况,最后进行病毒基因组稳定性检测。结果经MA104细胞培养的轮状病毒P[2]G3株在人二倍体细胞KMB17上可产生明显的细胞病变(CPE),但病变出现的时间随病毒传代次数的增加而延迟,抗原性也逐渐减弱。通过蚀斑筛选纯化得到的克隆病毒,可在KMB17细胞上稳定地增殖。以0.05MOI病毒量接种可产生稳定的CPE,时间为72～96h。连续传代至第10代,病毒滴度达105.5PFU/ml,病毒基因组稳定。结论轮状病毒P[2]G3株在人二倍体细胞KMB17上表现出毒力及增殖能力的衰退;经蚀斑筛选纯化可获得毒力较强的病毒株,并在KMB17细胞中稳定复制、增殖。     

基于CARIMA模型的自适应预测PID调节器的自适应递推算式的推导

本文针对ＰＩＤ调节器参数整定的困难性问题，提出了基于ＣＡＲＩＭＡ模型的自适应预测ＰＩＤ调节器的结构，并推导了一套相应的自适应递推算式，使ＰＩＤ的参数随着对象特性和环境条件的变化而变化。从而极大地提高了ＰＩＤ调节器的自适应性。     

交流风力发电系统的传递函数及分析

本文根据空气动力学及电学的有关公式,利用风力发电系统和电机的有关特性,推导出交流风力发电系统的传递函数。经对频率特性分析,指出系统动态参数的变化趋势,提出使风力发电系统稳定工作的最合理控制方式。     

基于几何造型的有限元网格的自适应生成

介绍一个基于几何造型系统的有限元分析的前处理系统。该系统可对几何造型的二维任意形体进行快速可靠的Ｄｅｌａｕｎａｙ三角剖分，提出网格自动生成的网格密度的控制和基于误差估计的自适应有限元网格生成算法，并给出了应用实例。     

An adaptive least-squares spectral collocation method with triangular elements for the incompressible Navier–Stokes equations

A least-squares spectral collocation scheme for the incompressible Navier–Stokes equations is proposed. Grid refinement is performed by means of adaptive triangular elements. On each triangle the Fekete nodes are employed for the collocation of the differential equation. On the element interfaces continuity of the functions is enforced in the least-squares sense. Equal-order Dubiner polynomials are used to obtain a stable spectral scheme. The collocation conditions and the interface conditions lead to an overdetermined system that can be solved efficiently by least-squares. The solution technique only involves symmetric positive-definite linear systems. The approach is first applied to the Poisson equation and then extended to singular perturbation problems where least-squares have a stabilizing effect. By adaptivity, a suitable decomposition of the domain is found where the boundary layer is well resolved. Finally, the method is successfully applied to the regularized driven-cavity flow problem. Numerical simulations confirm the high accuracy of the proposed spectral least-squares scheme.     

Learning styles and cognitive traits – Their relationship and its benefits in web-based educational systems

Different learners have different needs; they differ, for example, in their learning goals, their prior knowledge, their learning styles, and their cognitive abilities. Adaptive web-based educational systems aim to cater individual learners by customizing courses to suit their needs. In this paper, we investigate the benefits of incorporating learning styles and cognitive traits in web-based educational systems. Adaptivity aspects based on cognitive traits and learning styles enrich each other, enabling systems to provide learners with courses which fit their needs more accurately. Furthermore, consideration of learning styles and cognitive traits can contribute to more accurate student modelling. In this paper, the relationship between learning styles, in particular the Felder–Silverman learning style model (FSLSM), and working memory capacity, a cognitive trait, is investigated. For adaptive educational systems that consider either only learning styles or only cognitive traits, the additional information can be used to provide more holistic adaptivity. For systems that already incorporate both learning styles and cognitive traits, the relationship can be used to improve the detection process of both by including the additional information of learning style into the detection process of cognitive traits and vice versa. This leads to a more reliable student model.     

On error control in the element-free Galerkin method

The paper investigates discretisation error control in the element-free Galerkin method (EFGM) highlighting the differences from the finite element method (FEM). We demonstrate that the (now) conventional procedures for error analysis used in the finite element method require careful application in the EFGM, otherwise competing sources of error work against each other. Examples are provided of previous works in which adopting an FEM-based approach leads to dubious refinements. The discretisation error is here split into contributions arising from an inadequate number of degrees of freedom e_h, and from an inadequate basis e_p. Numerical studies given in this paper show that for the EFGM the error cannot be easily split into these component parts. Furthermore, we note that arbitrarily setting the size of nodal supports (as is commonly proposed in many papers) causes severe difficulties in terms of error control and solution accuracy. While no solutions to this problem are presented in this paper it is important to highlight these difficulties in applying an approach to errors from the FEM in the EFGM. While numerical tests are performed only for the EFGM, the conclusions are applicable to other meshless methods based on the concept of nodal support.