International Atomic Energy Agency's contributions to advances in nutritional and environmental metrology

For more than three decades the International Atomic Energy Agency (IAEA) has supported projects on food, nutrition and environment for strengthening the analytical capabilities in developing countries (DCs). Over time, such efforts have led to the development of proper study designs, harmonization of sampling protocols, adequate contamination control and evaluation of the suitability of competing analytical techniques for the determination of specific analytes. Collectively, these consistent IAEA initiatives have promoted harmonization of chemical measurements thus facilitating comparability of results of filed investigations. Importantly, the Agency's efforts have infused a measure of metrological awareness in measurements carried out in field studies, including physiological measurements. Nuclear and isotopic techniques have played an important role in reaching these goals by establishing reliable measurement processes for application in health care studies.     

On the use of nickel foil strain gages at varying temperatures

When a strain gage made of nickel foil attached on the surface of a specimen is subjected to repeated loads, the elastic stress is measured by observing slip-bands in the foil resulting from repeated strain. Calibration studies with rotating-bending tests at various temperatures between room temperature and 350°C are performed on round steel bars with nickel foil. The relation between the threshold stress for the first appearance of slip-bands and the number of stress cycles is examined at varying temperatures, which provides the calibration values of the nickel foil tested at varying temperatures. Assuming that the first appearance of slip-bands is based on the linear cumulative damage law, the calibration values at varying temperatures are calculated from those established by the calibration tests at several constant temperatures. It is found that the calculated calibration values agree well with the results obtained by the calibration tests at varying temperatures and that the calculation applying the linear cumulative damage law is a useful method to presume the calibration values at varying temperatures without performing the experiment.     

PALEOMONSOONS OF CHINA OVER THE LAST 130,000 YEARS——PALEOMONSOON VARIATION

Based upon the effect of land-sea interaction on the paleomonsoon variation and the time series of climatic proxy-indicators, the historical Asian monsoon variation over the last 130,000 and 18,000 years has been reconstructed with an emphasis on the basic characteristics of summer monsoon circulation. The monsoon-climatic cycles and associated model of environmental development over the central and eastern China are proposed and the mechanism of paleomonsoon variation of China preliminarily discussed. The variation of East Asian monsoon circulation should be regarded as a regional result of both solar-radiation changes and the global glacial-interglacial cycles. The episodic uplifting of the Qinghai-Xizang Plateau since the late Miocene has to a large extent controlled the forming and evolution of the paleomonsoon circulation of China.     

主成分分析在环境质量评价中的失效问题

在环境质量评价中,主成分分析被认为是一种客观而实用的评价方法.但大量的数据分析表明,主成分分析的评价结果并不一定符合实际情况,有时甚至完全失效,存在着一系列问题,而这些问题是由主成分分析本身的性质所决定的.     

PARTICIPATION IN INTERNATIONAL ENVIRONMENTAL AGREEMENTS: THE ROLE OF TIMING AND REGULATION

ABSTRACT. We analyze the formation of self‐enforcing international environmental agreements under the assumption that countries announce their participation either simultaneously or sequentially. It is shown that a sequential formation process opens up possibilities for strategic behavior of countries that may lead to inferior outcomes in terms of global abatement and welfare. We then analyze whether and under which conditions a regulator like an international organization, even without enforcement power, can improve upon globally suboptimal outcomes through coordination and moderation, given that recommendations must be Pareto‐improving to all parties.     

Data-driven preventive maintenance for a heterogeneous machine portfolio

We describe a data-driven approach to optimize periodic maintenance policies for a heterogeneous portfolio with different machine profiles. When insufficient data are available per profile to assess failure intensities and costs accurately, we pool the data of all machine profiles and evaluate the effect of (observable) machine characteristics by calibrating appropriate statistical models. This reduces maintenance costs compared to a stratified approach that splits the data into subsets per profile and a uniform approach that treats all profiles the same.     

Plankton growth dynamic driven by plankton body size in deterministic and stochastic environments

In this paper, we establish a new phytoplankton–zooplankton model by considering the effects of plankton body size and stochastic environmental fluctuations. Mathematical theory work mainly gives the existence of boundary and positive equilibria and shows their local as well as global stability in the deterministic model. Additionally, we explore the dynamics of V-geometric ergodicity, stochastic ultimate boundedness, stochastic permanence, persistence in the mean, stochastic extinction, and the existence of a unique ergodic stationary distribution in the corresponding stochastic version. Numerical simulation work mainly reveals that plankton body size can generate great influences on the interactions between phytoplankton and zooplankton, which in turn proves the effectiveness of mathematical theory analysis. It is worth emphasizing that for the small value of phytoplankton cell size, the increase of zooplankton body size can not change the phytoplankton density or zooplankton density; for the middle value of phytoplankton cell size, the increase of zooplankton body size can decrease zooplankton density or phytoplankton density; for the large value of phytoplankton cell size, the increase of zooplankton body size can increase zooplankton density but decrease phytoplankton density. Besides, it should be noted that the increase of zooplankton body size cannot affect the effect of random environmental disturbance, while the increase of phytoplankton cell size can weaken its effect. There results may enrich the dynamics of phytoplankton-zooplankton models.     

关于环境地质学的一些基本问题探讨

简要阐述了作者对有关环境地质学的一些基本问题的见解,包括;环境地质与地质环境的科学涵义;环境地质学与相关学科的关系;地质环境保护在整个环境保护中的应有地位;地质灾害的形成步骤及其防治途径;环境地质学的亟待完善领域等。同时也涉及整个环境科学的一些问题。     

防护林带：湍流的数学模型与计算机模拟

虽然防护林用于减小风速、控制热量和水汽传递及污染物扩散、 改善气候与环境、增加作物产量等已经有几百年了, 但直到近几十年, 人们才开始系统地研究防护林空气动力学的遮蔽机制.在本综述中,我 们考察了绕防护林带的流动与湍流控制机制,最新的模型与数值模拟 研究情况;通过数值模拟与实验数据的比较,来了解防护林带结构与防 风效果之间的关系;讨论数值分析如何及为什么能够得到所需要的结果. 本文将从多孔隙防护林带流动基本方程组的推导开始,讨论数值模型及 模拟过程,对附体与分离流动进行预测;分析了遮蔽机制与动量交换;对 风向、防护林密度、宽度和三维性对流动与湍流的影响作了系统的论 述.还对热流和土壤水分蒸发的新模型及数值模拟作了简述.最后,我们 对网络工作站、群和高性能分布式并行计算机及其对防护林带模型预 报能力的提高作了讨论.     

Microwave-assisted micro-solid-phase extraction for analysis of tetracycline antibiotics in environmental samples

In this study, a novel solid-liquid-solid extraction approach, which was termed ‘microwave-assisted micro-solid-phase extraction’ (MAE-μ-SPE), was developed. Target analytes were extracted from the sample into extraction solvent enhanced by microwave field, following adsorption by the adsorbent in the micro-solid-phase extraction device. Without any clean-up steps, the extracts were analysed by high performance liquid chromatography coupled with ultra-violet detector. The MAE-μ-SPE approach was developed for the extraction of four tetracycline antibiotics residues in environmental soil, sludge and atmospheric particulate matters. Variables affecting extraction procedures were systematically investigated. Low detection limits of 0.1–6.3 ng/g and low quantification limits of 0.33–20.7 ng/g were achieved under optimised conditions. The recoveries of antibiotics ranged from 70.6% to 110.5% with relative standard deviation of less than 15.1%. The predominance was showed when compared to conventional MAE and μ-SPE method. According to the results, MAE-μ-SPE was proved to be a simple and effective sample preparation method for the analysis of trace organic contaminants in environmental samples.