Optimisation of a selective method for the determination of organophosphorous triesters in outdoor particulate samples by pressurised liquid extraction and large-volume injection gas chromatography–positive chemical ionisation–tandem mass spectrometry

A selective analytical method for the determination of nine organophosphate triesters and triphenylphosphine oxide (TPPO) in outdoor particulate matter is presented. It involves a fully automated pressurised liquid extraction (PLE) step, integrating an alumina clean-up process, and subsequent determination by large-volume injection gas chromatography–positive chemical ionisation–tandem mass spectrometry (LVI-GC–PCI–MS/MS). The extraction variables (solvent, amount of adsorbent, temperature, time and number of cycles) were optimised using a multicriteria strategy which implements a desirability function that maximises both extraction and clean-up efficiencies while searching for the best-compromise PLE conditions. The final method affords quantification limits of between 0.01 and 0.3 μg g⁻¹ and recoveries of >80%, with the exceptions of the most polar analytes, TCEP and TPPO (~65%) for both urban dust and PM10 samples. Moreover, the method permitted the levels of these compounds in dust deposited outdoors (between LOD and 0.5 μg g⁻¹ for TEHP) and PM10 samples (between LOD and 2.4 μg m⁻³ for TiBP) to be measured and reported for the first time. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Retrospective LC-QTOF-MS analysis searching for pharmaceutical metabolites in urban wastewater

The presence of pharmaceuticals in the environment is a matter of major concern because of their wide consumption and their potential negative effect on the water quality and living organisms. After human and/or veterinary consumption, pharmaceuticals can be excreted in unchanged form as the parent compound and/or as free or conjugated metabolites. These compounds seem not to be completely removed during wastewater treatments and might finally arrive to surface and ground waters. Consequently, both parent pharmaceuticals and metabolites are target analytes to be considered in analytical methodologies. The satisfactory sensitivity in full-acquisition mode, high-resolution, exact mass measurements and MS/MS capabilities of hybrid quadrupole time-of-flight (QTOF) mass spectrometry make of this technique a powerful analytical tool for the identification of organic contaminants. In this study, the use of QTOF-MS with the aid of specialised processing-data application managers has allowed the retrospective analysis of pharmaceuticals metabolites in urban wastewater without the need for additional injection of sample extracts. Around 160 metabolites have been investigated in wastewater samples previously analysed only for parent compounds using LC-QTOF under MS(E) mode (simultaneous recording of two acquisition functions, at low and high collision energy). The retrospective analysis was applied to search for pharmaceutical metabolites in parent-positive effluent wastewaters from the Spanish Mediterranean region. Five metabolites, such as clopidogrel carboxylic acid or N-desmethyl clarithromycin, were identified in the samples.     

Spectral reflectance characteristics of different snow and snow-covered land surface objects and mixed spectrum fitting

The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area.The result showed that for a pure snow spectrum,the snow reflectance peaks appeared from visible to 800 nm band locations;there was an obvious absorption valley of snow spectrum near 1 030 nm wavelength.Compared with fresh snow,the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300～1 300,1 700～1 800 and 2 200～2 300 nm,the lowe...     

Urban air pollutants and their micro effects on medieval stained glass windows

Levels of urban gaseous and particulate pollutants were investigated in the Cathedral of Cologne, Germany in the framework of the EU-project “VIDRIO”. The purpose of this study was to evaluate the influence of a protective double glazing system on the preservation of ancient stained glass windows by sampling at protected and unprotected windows (indoors, in the interspace and outdoor of the Cathedral). The interspace between the ancient stained glass window and the protective glazing is flushed in the Cathedral by indoor air, hence isolating the historic glass from the outdoor air and exposing it to indoor air on both sides of the glass panels. Concentrations of aggressive gaseous pollutants such as NO₂, SO₂, O₃ and CO₂ as well as elemental concentrations of bulk particles and relative abundances of single particles were surveyed at all sampling locations. Elemental concentrations in bulk particulate matter were found to be significantly lower inside the Cathedral in comparison to the outdoor air. This result is advantageous for the stained glass windows. Single particle analysis of the samples from Cologne showed also soil dust and organic particles as well as sulphates and nitrates, from which the latter two compounds are dangerous for the stained glass windows. On the base of the obtained results, it can be concluded that the protective glazing system in the Cathedral of Cologne can be considered as predominantly advantageous from both the gases' point of view (except for NO₂-candles burning) and from the particles' point of view.     

The rank-size scaling law and entropy-maximizing principle

The rank-size regularity known as Zipf’s law is one of the scaling laws and is frequently observed in the natural living world and social institutions. Many scientists have tried to derive the rank-size scaling relation through entropy-maximizing methods, but they have not been entirely successful. By introducing a pivotal constraint condition, I present here a set of new derivations based on the self-similar hierarchy of cities. First, I derive a pair of exponent laws by postulating local entropy maximizing. From the two exponential laws follows a general hierarchical scaling law, which implies the general form of Zipf’s law. Second, I derive a special hierarchical scaling law with the exponent equal to 1 by postulating global entropy maximizing, and this implies the pure form of Zipf’s law. The rank-size scaling law has proven to be one of the special cases of the hierarchical scaling law, and the derivation suggests a certain scaling range with the first or the last data point as an outlier. The entropy maximization of social systems differs from the notion of entropy increase in thermodynamics. For urban systems, entropy maximizing suggests the greatest equilibrium between equity for parts/individuals and efficiency of the whole.     

Random-growth urban model with geographical fitness

This paper formulates a random-growth urban model with a notion of geographical fitness. Using techniques of complex-network theory, we study our system as a type of preferential-attachment model with fitness, and we analyze its macro behavior to clarify the properties of the city-size distributions it predicts. First, restricting the geographical fitness to take positive values and using a continuum approach, we show that the city-size distributions predicted by our model asymptotically approach Pareto distributions with coefficients greater than unity. Then, allowing the geographical fitness to take negative values, we perform local coefficient analysis to show that the predicted city-size distributions can deviate from Pareto distributions, as is often observed in actual city-size distributions. As a result, the model we propose can generate a generic class of city-size distributions, including but not limited to Pareto distributions. For applications to city-population projections, our simple model requires randomness only when new cities are created, not during their subsequent growth. This property leads to smooth trajectories of city population growth, in contrast to other models using Gibrat’s law. In addition, a discrete form of our dynamical equations can be used to estimate past city populations based on present-day data; this fact allows quantitative assessment of the performance of our model. Further study is needed to determine appropriate formulas for the geographical fitness.     

我国农村土地间接流转供应链的利益协调机制研究——基于委托代理模型

利益冲突是供应链中的一个共性问题,因而建立合理的利益协调机制对农村土地流转的成功运作无疑是重要的。本文应用博弈论建立了供应链中利益协调的博弈模型——一个两阶段的委托代理模型,以此来分析我国农村土地间接流转模式运作中存在的双重委托代理风险问题,以至于可采取各种措施和手段促进供应链中的信息沟通与协调行为。最后,通过数值模拟与数值算例说明了机制设计的有效性,并对分析结果进行验证。研究结果表明,通过选择合理的机制可以使供应链各成员的期望收益达到帕累托改进,从而实现农村土地间接流转供应链系统的协调。     

不同地类春小麦拔节期冠层光谱与叶绿素差异研究

为实现对不同地类春小麦叶绿素含量的无损估测,通过分析春小麦冠层光谱与叶绿素含量的相关性,以及对其红边拐点位置与叶绿素含量做回归分析,分别建立了水浇地和旱地春小麦叶绿素含量估测模型并检验了模型精度。结果表明: (1) 拔节期水浇地和旱地春小麦叶绿素含量差异较大,且前者明显大于后者。虽然各地类春小麦光谱反射率与叶绿素含量均有很好的相关性,但旱地春小麦的相关性在可见光和近红外波段均低于水浇地。(2)在可见光范围,旱地春小麦冠层光谱反射率高于水浇地,而在近红外区则相反。阴坡地由于土壤水分高,春小麦长势较好,冠层光谱特点与水浇地差异不大。(3)建立的不同地类春小麦反射光谱红边拐点位置与叶绿素含量的监测模型表明,水浇地春小麦叶绿素含量的监测可用线性模型,预测精度达94.06%。而旱地则宜用二项式模型,预测精度为97.15%,比其线性模型高10.48%。     

Spatial statistical analysis of the effects of urban form indicators on road-traffic noise exposure of a city in South Korea

The purpose of this study is to present a statistical model which can predict the noise level of road-traffic in urban area. A spatial statistical model which can take into account spatial dependency on geographically neighboring areas is constructed from a noise map of a city in South Korea. A system of 250 m × 250 m grid cells is placed on the city of Cheongju, South Korea, and the noise level and urban form indicators are averaged over each cell. The population-weighted mean of the noise level is subsequently regressed on the average urban form by adopting the spatial autoregressive model (SAR) and the spatial error model (SEM), as well as an ordinary least squares (OLS) model. Direct and indirect impacts are analyzed for a valid interpretation of the spatial statistical models. Factors such as GSI, FSI, traffic volume, traffic speed, road area density, and the fraction of industrial area turn out to have significant impacts on the noise level.