高压合成和变价化学

本文介绍了高压反应的兴起、发展和目前它在无机合成中的应用。重点阐述了高压合成中引起结构和性能变化的一些基本原理以及由高压反应合成出的一系列具有特殊价态化合物。

稀土元素掺杂长余辉发光材料研究的最新进展

介绍了长余辉材料的历史和近几年的发展。对长余辉材料中的一些问题 ,如余辉机理等进行了总结和探讨。从稀土元素变价化学的角度出发讨论了稀土离子在长余辉材料中的作用 ,介绍了长余辉材料设计的一些想法。提出了对长余辉材料今后发展的看法。

我国变价稀土化学与物理的研究现状

稀土元素的主体一镧系元素原子的电子层结构为[Xe]4f^(0-14)5d^(0-1)6s^2。当其失去两个6s和一个5d或4f电子后,形成了最常见的Ln^(3+),其中La^(3+),Gd^(3+)及Lu^(3+)

我国变价稀土化学与物理研究现状及展望

稀土变价或价态浮动是指稳定的正三价以外的价态。目前已发现9个非三价稀土元素。通过对变价稀土材料的合成,新材料的物理化学性质和价态转变过程的研究,人们发现变价稀土具有与正常正三价稀土迥然不同的特异性能和用途,变价稀土离子的研究已成为稀土物理化学中最活跃的学科分支之一。本文概述了我国在变价稀土的合成与分析,稀土价态转换规律,变价稀土的性能等方面的研究及取得的成果,提出了今后变价稀土研究课题的建议。

Water Security-based Hydrological Regime Assessment Method for Lakes with Extreme Seasonal Water Level Fluctuations：A Case Study of Poyang Lake,China

Extreme seasonal water level fluctuations characterize natural floodplain lakes in monsoon regions, which are crucial for ensuring lake water security, including flood prevention water supply and health of aquatic ecosystem. In order to achieve this goal, we established a hydrological regime assessment method based on a set of hydrological indicators for lakes with heavy seasonal water level fluctuations. The results suggest that time-sensitive hydrological indicators and specific time scales for various water security aspects must be considered. We discovered that it is more practical and meaningful to combine the water level classification derived from statistical analyses with characteristic hydrological values linked to water security. The case study of Poyang Lake results show that there are no discernable trends of Poyang Lake water regime status over the last 35 years, and the two periods of poor status are in accordance with climate variation in the lake basin area. Scholars and policy makers should focus on both floods and droughts, which are the main water security problems for Poyang Lake. It is hoped that this multi-scale and multi-element hydrological regime assessment method will provide new guidelines and methods for other international scholars of river and lake water assessment.

Authorized variance analysis with consumption rate

On the base of budget or plan information, comparing with actual results, making variance analysis, finding real reasons behind variance, this is important way of control and also important function of budget. However, without consideration of changes of environment, there are some limitations for static variance analysis with benchmark of plan data. Adjusting for benchmark according to actual condition, then doing variance analysis, these will improve utilization of variance analysis. Adjusted benchmark is often known as authorized cost/profit. For different understanding for authority concept, with RCA＇s （the abbreviation for Resource Consumption Accounting） view and numerical examples, this paper brings out the concept of consumption rate variance to promoting deeper understanding and analyzing reasons behind variance.

Environmental Changes on the Tibetan Plateau:Evaluation and Prediction

A research report on the environmental changes of the Tibetan Plateau from the past 2,000 years to a century ahead has been released by the Institute of Tibetan Plateau Research,Chinese Academy of Sciences.After a three-year investigation into the plateau areas in southwest China’s Tibet Autonomous Region with an average altitude of over 4,500 meters,

The bond evolution mechanism of covalent sulfurized carbon during electrochemical sodium storage process

The excellent energy storage performance of covalent sulfur-carbon material has gradually attracted great interest. However, in the electrochemical sodium storage process, the bond evolution mechanism remains an elusive topic. Herein, we develop a one-step annealing strategy to achieve a high covalent sulfur-carbon bridged hybrid(HCSC)utilizing phenylphosphinic acid as the carbon-source/catalyst and sodium sulfate as the sulfur-precursor/salt template, in which the sulfur mainly exists in the forms of C–S–C and C–S–S–C. Notably, most of the bridge bonds are electrochemically cleaved when the cycling voltage is lower than0.6 V versus Na/Na+, leading to the appearance of two visible redox peaks in the following cyclic voltammogram(CV) tests.The in-situ and ex-situ characterizations demonstrate that S^2- is formed in the reduction process and the carbon skeleton is concomitantly and irreversibly isomerized. Thus, the cleaved sulfur and isomerized carbon could jointly contribute to the sodium storage in 0.01–3.0 V. In a Na-S battery system, the activated HCSC in cut off voltage window of 0.6–2.8 V achieves a high reversible capacity(770 mA h g^-1 at 300 mA g^-1). This insight reveals the charge storage mechanism of sulfur-carbon bridged hybrid and provides an improved enlightenment on the interfacial chemistry of electrode materials.

Impacts of climate change on the ecotoxicology of chemical contaminants in estuarine organisms

Global climate change effects will vary geographically, and effects on estuaries should be independently considered. This review of the impacts of climate change on the ecotoxicology of chemical contaminants aims to summarize responses that are specific to estuafine species. Estuarine organisms are uniquely adapted to large fluctuations in temperature, salinity, oxygen, and pH, and yet future changes in climate may make them more susceptible to chemical contaminants. Recent research has hig- hlighted the interactive effects of chemical and nonchemical stressors on chemical uptake, metabolism, and organism survival. Assessments have revealed that the nature of the interaction between climate variables and chemical pollution will depend on es- tuarine species and life stage, duration and timing of exposure, prior stressor exposure, and contaminant class. A need for further research to elucidate mechanisms of toxicity under different abiotic conditions and to incorporate climate change factors into toxicity testing was identified. These efforts will improve environmental risk assessment of chemical contaminants and manage- ment capabilities under changing climate conditions [Current Zoology 61 （4）： 641-652, 2015].