摘要：Pavement snow and icing are worldwide problems, but effective countermeasures are just beginning to be developed in China. The two most common snow and ice removal methods are mechanical clearance and chemical melting, and the advantages and disadvantages of each approach are discussed here, including environmental and structural damage caused by corrosive snow melting agents. New developments in chemical melting agents and mechanical equipment are discussed, and an overview of alternative thermal melting systems is presented, including the use of geothermy and non-geothermal heating systems utilizing solar energy, electricity, conductive pavement materials, and infrared/microwave applications. Strategic recommendations are made for continued enhancement of public safety in snow and ice conditions.

摘要：Ecosystems in China have been absorbing anthropogenic CO2 over the last three decades. Here, we assess future carbon uptake in China using models from phase 5 of Coupled Model Intercomparison Project under four socio-economic scenarios. The average of China's carbon sink from 2006 to 2100 represented by multimodel mean net ecosystem production(NEP) is projected to increase(relative to averaged NEP from 1976 to 2005) in the range of 0.137 and 0.891 Pg C a-1across differentscenarios. Increases in NEP are driven by increases in net primary production exceeding increases in heterotrophic respiration, and future carbon sink is mainly attributed to areas located in eastern China. However, there exists a considerable model spread in the magnitude of carbon sink and model spread tends to be larger when future climate change becomes more intense. The model spread may result from intermodel discrepancy in the magnitude of CO2 fertilization effect on photosynthesis, soil carbon turnover time, presence of carbon-nitrogen cycle and interpretation of land-use changes. For better quantifying future carbon cycle, a research priority toward improving model representation of these processes is recommended.

摘要：Sedimentary pigments are useful proxy indicators of phytoplankton biomass, community structure, primary productivity and human influence in lacustrine and oceanic ecosystems. Pigments are relatively labile due to their complex chemical structures, which makes the extraction and analysis of sedimentary pigments challenging. In addition, it is important to select appropriate methods to study sedimentary pigments in regions which lack previous investigations. In this study, we adopted the L9（34） orthogonal design to develop methods of extraction and HPLC （high performance liquid chromatography） analysis of sedimentary pigments at two lakes on the Tibetan Plateau： meromictic lake-Dagze Co and dimictic lake-Jiang Co. The orthogonal design comprises 9 combinations of various parameters for extraction and HPLC analysis. The results show that the type and volume of solvent are the most important factors for pigment extraction, and the mobile phase and column selection are the most important for HPLC analysis. For the study sites, we found that the best methods to extract sedimentary pigments are as follows： the use of a mixture of acetone：methanol：water （80： 15：5, v：v：v） as the extraction solvent; sol- vent/sample ratio of 10 mL/g; sonication for 30 s and standing extraction for 6 h. The best methods for HPLC analysis are as follows： Zorbax Eclipse plus C8 column with mobile phase A, methanol：acetonitrile：0.25 M aqueous pyridine （50： 25：25, v ： v ： v） and mobile phase B, methanol： acetonitrile： acetone （20： 60： 20, v： v： v）; pH of mobile phase A adjusted to 6 with acetic acid; and HPLC column temperature maintained at 40~C. The study provides an experimental basis for future investigations of past changes in primary productivity and the response of lake ecosystems to climate change and human activities on the Tibetan Plateau.

摘要：Based on the obtained data of half-lives（t1/2） for 31 polychlorinated biphenyl congeners（PCBs）, 3D quantitative structure-activity relationship（QSAR） pharmacophore was used to establish a 3D QSAR model to predict the t1/2 values of the remaining 178 PCBs, using the structural parameters as independent variables and lgt1/2 values as the dependent variable. Among this process, the whole data set（31 compounds） was divided into a training set（24 compounds） for model generation and a test set（7 compounds） for model validation. Then, the full factor experimental design was used to research the potential second-order interactional effect between different substituent positions, obtaining the final regulation scheme for PCB. At last, a 3D QSAR pharmacophore model was established to validate the reasonable regulation targeting typical PCB with respect to half-lives and thermostability. As a result, the cross-validation correlation coefficient（q2） obtained by the 3D QSAR model was 0.845（〉0.5） and the coefficient of determination（r2） obtained was 0.936（〉0.9）, indicating that the models were robust and predictive. CoMSIA analyses upon steric, electrostatic and hydrophobic fields were 0.7%, 85.9%, and 13.4%, respectively. The electrostatic field was determined to be a primary factor governing the tt/2. From CoMSIA contour maps, tl/2 increased when substi- tuents possessed electropositive groups at the 2＇-, 3-, Y-, 5- and 5＇- positions and electronegative groups at the 3-, 3＇-, 5-, 6- and 6＇- positions, which could increase the PCB stability in transformer insulation oil. Modification of two typical PCB congeners（PCB-77 and PCB-81） showed that the lgtl/2 for three selected modified compounds increased by 13%（average ratio） compared with that of each congener and the thermostability of them were higher, validating the reasonability of the regulatory scheme obtained from the 3D QSAR model. These results are expected to be beneficial in predicting tl/2 values of PCB homologues and d

摘要：The adoption of both Nature-based Solutions(NbS)and a system perspective is a hot issue and an area in which there is much room for improvement in ecological protection and *** study takes Altay region as an example,an area located in Xinjiang,China,which is an important ecological corridor of the national key functional area and the core area of the Belt and Road but has a fragile ecological environment and needs much enhancement in ecological protection and *** by the concept of"mountains-rivers-forestsfarmlands-lakes-grasslands(MRFFLG)system is a life community",the coupling relationship of the various MRFFLG elements,the main ecological environmental problems and the integrated countermeasures for protection and restoration in Altay region have been analyzed in this *** study shows that Altay region has a typical meta-ecosystem of mountain,oasis,and desert,and the connections by rivers and lakes make the ecosystem links within the region much *** interweaving of resource-environmental-ecological issues of the aquatic ecosystem,degradation of the quality of terrestrial ecosystems such as forests,grasslands and farmlands,the increased ecosystem fragmentation and ecological risks are the major ecological environmental issues in this *** study takes the improvement of the ecosystem health and function in Altay region as the core goal of regional ecological protection and ***,we establish a zoning governance pattern from the perspective of ecosystem integrity;second,we design governance strategies for different zones with the goal of synergistic improvements in the ecosystem functions;and finally,we clarify the key engineering tasks in different zones from the perspective of ecosystem *** conservation and restoration of the MRFFLG system is a prime example of the application and development of NbS in *** paper constructs an analytical framework for identifying regional life communiti

摘要：The unreasonable utilization and trade-offs of the multifunctional landscape is one of the important causes leading to ecological *** the relationship,heterogeneous process and driving mechanism between landscape function and human well-being can provide a scientific basis for achieving a win-win situation of regional development and ecological protection,and it is also an important issue for relevant scientific *** this paper,we reviewed the current state of knowledge regarding landscape function and ecological risk,identified the feedback mechanisms among landscape change,landscape function,human well-being and ecological risk,constructed the ecological risk assessment framework based on landscape functions,and sorted out the key scientific issues and research *** interconnections between the multifunctional landscape,human well-being,and ecological risk comprise an important scientific issue in ecological risk ***,there is a lack of understanding of the spatial-temporal characteristics of landscape function trade-offs,and there is also a lack of systematic and standardized methods for the identification and comprehensive evaluation of landscape *** ecological risk management and the methodologies that integrate the two processes of nature and humanity is an inevitable trend for future *** landscape structure,function and process into ecological risk assessment,as well as focusing on the combination of human well-being,landscape function trade-off and ecological risk control policy design are important issues to be studied.

摘要：It is well-known that global warming due to anthropogenic atmospheric greenhouse effects advanced the start of the vegetation growing season （SOS） across the globe during the 20th century. Projections of further changes in the SOS for the 21st century under certain emissions scenarios （Representative Concentration Pathways, RCPs） are useful for improving understanding of the consequences of global warming. In this study, we first evaluate a linear relationship between the SOS （defined using the normalized difference vegetation index） and the April temperature for most land areas of the Northern Hemisphere for 1982-2008. Based on this relationship and the ensemble projection of April temperature under RCPs from the latest state-of-the-art global coupled climate models, we show the possible changes in the SOS for most of the land areas of the Northern Hemisphere during the 21st century. By around 2040-59, the SOS will have advanced by -4.7 days under RCP2.6, -8.4 days under RCP4.5, and -10.1 days under RCPS.5, relative to 1985-2004. By 2080-99, it will have advanced by -4.3 days under RCP2.6, -11.3 days under RCP4.5, and -21.6 days under RCP8.5. The geographic pattern of SOS advance is considerably dependent on that of the temperature sensitivity of the SOS. The larger the temperature sensitivity, the larger the date-shift-rate of the SOS.

摘要：以著名的LiB_(3)O_(5)为模板,通过增强其结构中B_(2)O_(5)的夹角使双折射更小,在封闭体系中通过高温溶液法获得了两种新的用于制造零级波片的双折射晶体Li_(2)MLaB_(18)O_(30)(M=Rb,Cs).有趣的是,相邻的B_(2)O_(5)接近垂直排列,使得它们表现出比商用石英晶体(Δn~0.0092在可见光区域)小得多的双折射率(分别为0.0032@532 nm和0.0027@532 nm).此外,Li_(2)MLaB_(18)O_(30)(M=Rb,Cs)晶体的紫外截止边均低于200 nm,表明它们可用作深紫外区域的零级波片材料.

摘要：Future changes in tropical cyclone(TC)activity over the western North Pacific(WNP)under the representative concentration pathway RCP4.5 are investigated based on a set of 21 st century climate change simulations over East Asia with the regional climate model RegCM4 driven by five global *** RegCM4 reproduces the major features of the observed TC activity over the region in the present-day period of 1986-2005,although with the underestimation of the number of TC genesis and intensity.A low number of TCs making landfall over China is also *** the end of the 21st century(2079-98),the annual mean frequency of TC genesis and occurrence is projected to increase over the WNP by16%and 10%,*** increase in frequency of TC occurrence is in good agreement among the simulations,with the largest increase over the ocean surrounding Taiwan Island and to the south of *** TCs tend to be stronger in the future compared to the present-day period of 1986-2005,with a large increase in the frequency of strong *** addition,more TCs landings are projected over most of the China coast,with an increase of~18%over the whole Chinese territory.

摘要：Topological nodal line（DNL） semimetals, a closed loop of the inverted bands in its bulk phases, result in the almost flat drumhead-like non-trivial surface states（DNSSs） with an unusually high electronic density near the Fermi level. High catalytic active sites generally associated with high electronic densities around the Fermi level, high carrier mobility and a close-to-zero free energy of the adsorbed state of hydrogen（？G_（H＊）≈0） are prerequisite to design alternative of precious platinum for catalyzing electrochemical hydrogen production from water. By combining these two aspects, it is natural to consider if the DNLs are a good candidate for the hydrogen evolution reaction（HER） or not because its DNSSs provide a robust platform to activate chemical reactions. Here, through first-principles calculations we reported a new DNL TiSi-type family, exhibiting a closed Dirac nodal line due to the linear band crossings in k_y=0 *** hydrogen adsorbed state on the surface yields ？G_（H＊） to be almost zero and the topological charge carries participate in HER. The results highlight a new routine to design topological quantum catalyst utilizing the topological DNL-induced surface bands as active sites, rather than edge sites-, vacancy-,dopant-, strain-, or heterostructure-created active sites.