Aerosol oxalate and its implication to haze pollution in Shanghai, China

A total of 238 samples of PM2.5and TSP were analyzed to study the characteristics,sources,and formation pathways of aerosol oxalate in Shanghai in four seasons of 2007.The concentrations of oxalate were0.07–0.41 lg/m3in PM2.5and 0.10–0.48 lg/m3in TSP,respectively.Oxalate displayed a seasonal variation of autumn[summer[winter[spring in both PM2.5and TSP and was dominantly present in PM2.5in all samples.Correlation between oxalate and K?and high ratio of oxalate/K?suggested that biomass burning was a secondary source of aerosol oxalate in Shanghai,in addition to urban VOCs sources(vehicular and industrial emissions),especially in autumn.Secondary formation accounted for the majority of aerosol oxalate in Shanghai,which was supported by the high correlation of oxalate with nssSO42-,K?and NO3-,proceeding from different mechanisms.Relatively high ambient RH together with high cloud cover was found benefiting the secondary formation of aerosol oxalate.The in-cloud process(aqueous-phase oxidation)was proposed to be likely the major formation pathway of aerosol oxalate in Shanghai,which was supported by the high correlation of oxalate with nss-SO42-and K?,dominant residence of oxalate in droplet mode and result of favorable meteorological condition analysis.High correlation of oxalate and NO3-reflected the OH radical involved oxidation chemistry of the two species in the atmosphere and also suggested that gas-particle surface reactions and the evaporation–condensation process were both possible secondary formation pathways of aerosol oxalate in coarser particle mode([1.0 lm).As a major water-soluble organic compound in aerosols,concentration of oxalate showed a distinct negative correlation to the atmospheric visibility,which implied that aerosol organic compounds could play an important role in haze pollution as well as in air quality in Shanghai.     

Monitoring dynamic changes of global land cover types:fluctuations of major lakes in China every 8 days during 2000–2010

Remote sensing images can be used to delineate variations in the area of lakes and to assess the influence of environmental changes and human activities.However,because lakes are dynamic,results obtained from individual images acquired on a single date are not representative and do not accurately reflect ongoing changes.In this study,we used 8-day moderate resolution imaging spectroradiometer(MODIS)composite data from 2000 to2010 to map water surface changes over 629 lakes in China.We combined automatic extraction of training data and support vector machine classification to derive the spatial distribution of these large water bodies.The producer’s and user’s accuracies for MODIS images were91.06%and 89.81%,respectively,when compared with interpretation results from 30 m resolution Landsat images taken on similar days.Area changes,variability,inundation intensity,and rainy seasons of the 629 lakes were analyzed based on this multi-temporal lake database.The total area of the 629 lakes increased over the study period,primarily as a result of the expansion of lake areas on the Tibetan Plateau.There were 12 lakes with a maximum area[1,000 km2,and six of these decreased in area from 2000to 2010.The shrinkages of Poyang Lake and Dongting Lake were-54.76 and-25.08 km2/a,respectively.The area of lakes on Tibetan Plateau,in northern Xinjiang,northeastern Inner Mongolia,and northeastern China varied little,while lakes on the Yangtze Plain,in southern Inner Mongolia,and central Xinjiang fluctuated considerably.Inundation intensity increased for lakes on the Tibetan Plateau,in northern Xinjiang,Heilongjiang,and Jilin,while inundation extent decreased in central Xinjiang,southern Tibet,southern Inner Mongolia,Sichuan,and on the Yangtze Plain.This study is an attempt to develop high-frequency specific land cover maps to improve applicability of general land cover maps.The lake products serve as an important supplement to hydrologic data.The lake database enables the generation of new land surface process models,which could improve the precision of simulations,based on more accurate observations of dynamic lake systems.     

Theoretical study of spin-orbit coupling and zero-field splitting in the spin-forbidden two-state reaction between cobaltacyclopentadiene and isocyanate

The two-state reaction mechanism of CpCo(C_4H_4)with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level.A study is described for the computation of spin-orbit coupling of triplet state of the minimal energy crossing point(CP)with their singlet states and of the zerofield splitting(ZFS)parameters of the triplet states,including the full one-and two-electron terms of the BreitPauli Hamiltonian.There are two key crossing points along this two-state reaction pathway.The first crossing point—CP2 exists near~1B.The reacting system will change its spin multiplicity from the triplet state to the singlet state near this crossing region.Although the spin-orbit coupling interaction and ZFS D-tensor of the CP2 region are very strong,the reaction system will occur the reverse intersystem crossing from T_1 to S_0.Therefore,its spin-flip efficiency may be lower.The second crossing point,CP3will again change its spin multiplicity from the singlet state to the triplet state in the Co-Cr bond activation pathway,leading to a decrease in the barrier height of~1TS(CF)from19.5 to 9.5 kcal/mol(1cal=4.182 J),and the efficiency of intersystem crossing from S_0 to T_1 is high because the larger spin-orbit coupling(SOC)matrix elements will result in the overpopulations of the three sublevels of T_1(3.30×10~(-1),3.32×10~(-1),and 3.38×10~(-1),respectively).     

Hesperomyces virescens （Fungi,Ascomycota, Laboulbeniales） attacking Harmonia axyridis （Coleoptera,Coccinellidae） in its native range

This study intended to find data on obligate ec- toparasitic Laboulbeniales （Fungi, Ascomycota） on Chinese Harmonia axyridis （Coleoptera, Coccinellidae）. After having screened over four thousand dried specimens of H. axyridis and close relatives, we present the first （historical） record of Chinese H. axyridis infected with Hesperomyces virescens. We suggest that H. t, irescens is a historically globally dis- tributed species and hypothesize that （native） infection was lost when H. a~a;ridis was introduced in North America.     

Label-free selective sensing of Pb2＋ lead（II） sensors based on the aggregation of a pyrene fluorescent probe

In the present work, we report a label-free fluo- rescence turn-on approach for the sensitive and selective sensing of Pb2＋. Pyrene with one positive charge was used as the fluorescent probe, and thrombin aptamer （TBA）, which was a G-rich oligonucleotide, was employed to form G-quadruplex with lead（II）. When TBA and Pb2＋ were mixed with lead（II） in an aqueous solution, it was folded into a stable G-quadruplex. Subsequently, a single-stranded nucleic acid-specific nuclease S1 was added. The G-quad- ruplex stabilized by Pb2＋ lead（II） had markedly a significant resistant ability to nuclease S1 digestion. However, in the absence of Pb2＋ lead（II）, no quadruplex or less stable quadruplex was formed and TBA was digested by nuclease S1 in 3 min under the optimized experimental conditions. Finally, pyrene probe was Pb2＋ lead（II）. Electrostatic mixed with oligonucleotide in interactions between oligonu- cleotide （a polyanion） and the probe induced the aggregation of the probe, which in turn produced strong emission of the strong pyrene excimer emission. The intensity of the induced excimer emission was directly proportional to the amount of Pb2＋ added. Our approach shows good selectivity and sen- sitivity for the detection of Pb2＋ with a limit of detection limit as low as 800 nmol/L.     

Geochemical characteristics and zones of surface snow on east Antarctic Ice Sheet

The surface-snow geochemical characteristics are discussed on the East Antarctic Ice Sheet, depending on the stable isotopes ratios of oxygen and hydrogen, concentration of impurities (soluble-ions and insoluble micro-particle) in surface snow collected on the ice sheet. The purpose is to study geochemical zones on the East Antarctic Ice Sheet and to research sources and transportation route of the water vapor and the impurities in surface snow. It has been found that the ratio coefficients, as S1, d1 in the equation δD =S1δ^18O d1, are changed near the elevation 2000 m on the ice sheet. The weight ratio of Cl^-/Na^ at the area below the elevation of 2000 m is close to the ratio in the sea salt; but it is about 2 times that of the sea salt, at the inland area up to the elevation of 2000 m. The concentrations of non-sea-salt Ca^2 ion (nssCa^2 ) and fine-particle increase at the interior up to the elevation 2000 m. At the region below the elevation of 2000 m, the impurity concentration is decreasing with the elevation increasing. Near coastal region, the surface snow has a high concentration of impurity, where the elevation is below 800 m. Combining the translating processes of water.vapor and impurities, it suggests that the region up to the elevation 2000 m is affected by large-scale circulation with longitude-direction, and that water-vapor and impurities in surface snow come from long sources. The region below the elevation 2000 m is affected by some strong cyclones acting at peripheral region of the ice sheet, and the sources of water and impurities could be at high latitude sea and coast. The area below elevation 800 m is affected by local coastal cyclones.     

Obtaining the best possible predictions of habitat selection for wintering Great Bustards in Cangzhou,Hebei Province with rapid machine learning analysis

Great Bustards （Otis tarda dybowskii） are one of the world＇s heaviest flying birds, occupying grassland hab- itats in Eastern Asia. Our study is located at the most eastern Chinese wintering site in Cangzhou, Hebei Province, where approximately 100 individuals are concentrated in a small area （17.53 km2）. Solid information is still lacking about the wintering areas for this subspecies in its eastern range and specifically for China. The study area consists of intensely used farmland in proximity to humans and is lacking con- servation areas and wild, open fields. Here, we present our results from two years of field data collection on habitat selection. We choose a machine learning model approach based on a rapid assessment methodology for the winter habitat of the Great Bustard. It is based on a spatial analysis of the best available environmental data, which were col- lected relatively quickly. These relatively new methods in ecology are based on an ensemble of decision trees and include algorithms such as TreeNet, Random Forest and CART used in parallel. In this study, we collected bustard droppings （presence only） from 48 locations between December 2011 and January 2012 and used the sites as training data. Droppings from 23 locations were collected in November 2012, and those sites were used as test data. We used eight environmental variables as predictor layers for the response variable of bustard presence/availability. We employed a Geographic Information System （ArcGIS 10.1and Geospatial Modelling Environment） and Google Earth. Compared with the other three models, we found that pre- dictions from Random Forest obtained a significant differ- ence between presence and absence. According to this model, the three most important factors for wintering Great Bustards are distance to residential area, distance to water pools, and farmland area. Our model shows that wintering Great Bustards prefer locations that are over 400 m away from residential areas, within 900 m of water pools and on areas o     

金产品CAD/CAPP系统的研究开发

本文针对钣金产品的特点,通过实例介绍了钣金产品ＣＡＤ／ＣＡＰＰ系统开发的一般方法,重点阐述了系统建模技术和信息集成技术     

40Ar/39Ar ages and stable isotopes of supergene jarosite from the Baiyin VHMS ore field,NE Tibetan Plateau with paleoclimatic implications

Supergene jarosite is widely distributed in weathering profiles derived from hypogene sulfide ores.Precise40Ar/39Ar dating and determination of hydrogen and oxygen isotopes of supergene jarosite can not only place tight constraints on the timing and history of continental weathering and supergene enrichment of sulfide ore deposits,but also shed significant insights into paleoclimatic conditions and tectonic uplift responsible for the weathering.In this paper,we present a preliminary study of40Ar/39Ar geochronology and stable isotope geochemistry of supergene jarosite from the early Paleozoic Zheyaoshan volcanic-hosted massive sulfide deposit of the Baiyin ore field located in the eastern portion of the Qilian Mountain along the northeastern(NE)margin of the Tibetan Plateau in an attempt to better understand the climatic conditions prevailed during the pervasive weathering in the region.Jarosite from the Zheyaoshan mining area occurs either as gravels within alluvial deposits over low-relief flat-top hills or cm-wide veins crosscutting weathered sulfide ores or their wall rocks.The gravels consist of massive jarosite aggregates with tabular crystal morphology and contain 8.21 wt%–8.31 wt%K2O on average.Two jarosite grains extracted from the gravels(08-02-2 and 08-02-5)yield well-defined40Ar/39Ar plateauages of 37.1±0.3 and 41.2±0.4 Ma(2r),respectively.They have dD values of-133%and-156%,and d18OSO4values of 2.6%and 2.5%.The vein-type jarosite consists of hexagonal pyramid crystals and contains much lower K2O,averaging at 2.44 wt%–2.72 wt%.Two jarosite veins(06-16-3 and 06-16-4)yield similar plateau ages of 3.2±0.1 and 3.3±0.1 Ma(2r),respectively.These jarosite veins have dD values of-158%and-160%,and d18OSO4values of 2.8%and 2.5%.The40Ar/39Ar ages indicate that sulfide ores of the Zheyaoshan deposit must have been brought to the surface since the late Eocene,and subsequently subjected to prolonged oxidation and supergene enrichment.The precipitation and preservation of jarosite in weathering profiles indicate that arid–semiarid climatic conditions must have been prevailed since the late Eocene.The hydrogen and oxygen isotopes of the jarosite further point to variation of climatic conditions in the area,with the Pliocene being slightly cooler relative to the late Eocene.Given that weathering profiles overlying sulfide ore deposits are widely distributed along the Qilian Mountain,systematic studies of40Ar/39Ar geochronology and stable isotope geochemistry of jarosite-group minerals from these profiles would provide valuable information on the timing and evolution of regional tectonic uplift,paleoclimatic changes,and supergene mineralization in this mountainous belt along the NE edge of the Tibetan Plateau.     

板片空间结构稳定分析中的数值计算模型

分析了板片空间结构体系中板与骨架共同工作问题的力学机理,将接触问题的理论和方法应用到结构稳定问题的研究中,建立了相应的数值计算模型.基于共同工作问题的数值模拟,分析了该结构体系中板与金属骨架之间的接触单元安置、初始接触刚度对结构稳定分析计算的影响,提出了接触单元安置的原则和初始接触刚度选取的合理范围.数值计算结果与试验结果比较表明:该数值计算模型计算结果和试验结果符合较好,能够真实地反映板片空间结构实际的稳定工作状态,是合理和可靠的,而位移完全协调数值模型的结果较试验结果偏高,用于设计偏于不安全.     

钣金件CAD/CAM集成的产品特征建模研究

针对钣金类零件，描述了特征的分类及其联系，提出了采用面向对象的建模技术来建立铍金件的特征模型，并给出了实例．     

复杂型面板料成形数值模拟快速有限元建模

提出并实现了直接从测量到的空间散乱点直接生成有限元网络的新方法,使具有大尺寸复杂型面金属板料冲压成形整个数值模拟有限元建模的工作量大大降低,并使得建模的自动化程度提高。为了解决建模过程中初始坯料形状未知的问题,比较了不同的初始毛坯预测方法,提出用一步模拟法从已得到模具的有限元网格进行反推,预测出毛坯的基本形状和尺寸。     

Fortnightly variations in the flow velocity of Rutford Ice Stream, West Antarctica

Most of the ice lost from the Antarctic ice sheet passes through a few fast-flowing and highly dynamic ice streams. Quantifying temporal variations in flow in these ice streams, and understanding their causes, is a prerequisite for estimating the potential contribution of the Antarctic ice sheet to global sea-level change. Here I show that surface velocities on a major West Antarctic Ice Stream, Rutford Ice Stream, vary periodically by about 20 per cent every two weeks as a result of tidal forcing. Tidally induced motion on ice streams has previously been thought to be limited to diurnal or even shorter-term variations. The existence of strong fortnightly variations in flow demonstrates the potential pitfalls of using repeated velocity measurements over intervals of days to infer long-term change.     

基于SQL Server平台复杂地质体FLAC3D模型的构建

由于FLAC3D软件建立复杂三维地质体模型难度大、易出错,提出一种新的建模方法,即提取三维地质体建模数据并进行编辑成相应的表,把表导入SQL Server软件中,通过SQL查询语言生成FLAC3D可直接读取模型数据文件,从而实现在FLAC3D软件中准确、快速和自动化建立复杂三维地质模型的目的.通过云南某矿山的三维建模实例检验了该方法的可行性和高效性.结果表明:该方法在FLAC3D中建立复杂地质体模型具有一定的参考价值.     

35 ka BP climate simulations in East Asia and probing the mechanisms of climate changes

Interglacial or postglacial climates are all of charac-teristic of warmer conditions. However, if condition asso-ciated with the warm feature is wetter or drier than today,it would produce different impacts on natural environ-ments and human society. Quaternary studies found thatclimate with warm-dry or warm-wet conditions had oc-curred in China during the last 40—30 ka BP[1]. For ex-ample, it was warmer than the present during themid-Holocene (3—8 ka BP) and the late phases of MarineIsot…     

Sedimentary environments of the Cenozoic sedimentary debris found in the moraines of the Grove Mountains, east Antarctica and its climatic implications

During the field work of the 1998～1999's and 1999～2000's Chinese National Antarctic Research Expedition (CHNARE) in the Grove Mountains, east Antarctica, some Cenozoic sedimentary debris are found in two terminal moraine banks over the blue ice near Harding Mount in the center of this region. All the debris are of characteristics of glaciogenic diamicton and belong to the products of the glacial movements of the East Antarctic Ice Sheet. In this paper, the authors make a detailed study on the sedimentary environments of the sedimentary debris through petrologic, sedimentological, mineralogical, and geo-chemical methods. Characteristics of their sedimentary textures and structures, grain size distributions, quartz grains' surface textures and features, together with their geo-chemical compositions all show that these sedimentary rocks are a kind of subglacial lodgement tills which are deposited in the ice sheet frontal area by reactions of glacial movements and glaciogenic melt water. Their palaeoenvironmental implications in revealing the retreat history of East Antarctic Ice Sheet are discussed. The authors draw the conclusion from current study that the glacial frontal of the East Antarctica Ice Sheet might have been retreated to this area during the Pliocene Epoch, which represents a warm climate event accompanied by a large-scale ice sheet retreat in Antarctica at that time.     

Ice radar investigation at Dome A, East Antarctica: Ice thickness and subglacial topography

Dome A, located in the central East Antarctic ice sheet (EAIS), is the highest summit of the Antarctic ice sheet. From ice-sheet evolution modeling results, Dome A is likely to preserve over one million years of the Earth’s paleo-climatic and -environmental records, and considered an ideal deep ice core drilling site. Ice thickness and subglacial topography are critical factors for ice-sheet models to determine the timescale and location of a deep ice core. During the 21st and 24th Chinese National Antarctic Research Expedition (CHINARE 21, 2004/05; CHINARE 24, 2007/08), ground-based ice radar systems were used to a three-dimensional investigation in the central 30 km×30 km region at Dome A. The successfully obtained high resolution and accuracy data of ice thickness and subglacial topography were then interpolated into the ice thickness distribution and subglacial topography digital elevation model (DEM) with a regular grid resolution of 140.5 m×140.5 m. The results of the ice radar investigation indicate that the average ice thickness in the Dome A central 30 km×30 km region is 2233 m, with a minimal ice thickness of 1618 m and a maximal ice thickness of 3139 m at Kunlun Station. The subglacial topography is relatively sharp, with an elevation range of 949–2445 m. The typical, clear mountain glaciation morphology is likely to reflect the early evolution of the Antarctic ice sheet. Based on the ice thickness distribution and subglacial topography characteristics, the location of Kunlun Station was suggested to carry out the first high-resolution, long time-scale deep ice core drilling. However, the internal structure and basal environments at Kunlun Station still need further research to determine.     

工程结构接触问题的研究及进展

针对国内外工程结构接触问题的研究现状，阐述了各类研究方法的基本思想和主要特点，指出了其中一些尚待解决的问题．介绍了这一问题求解的优化计算方法以及板片结构接触计算模型，所建立的结构分析和计算模型能真实反映工程结构的实际工作状态，给工程结构的设计和应用提供了理论计算依据．     

可变码率压缩和音速、音调调整的音频信号的正弦模型

提出一种用于可变码率音频编码的正弦 噪声(SN)模型．提出了对正弦模型进行本质上的增强．从大、中、小三个前后衔接的尺度上对音频信号进行时域重叠相加(overlap-add)的正弦分析时引入了心理声学模型加权的匹配跟踪算法(matching pursuits algorithm)，将大尺度正弦分析-合成后的余量送入相对小的尺度进行分析，以达到相应的分辨率．这种算法有效的解决了正弦模型固有的预回声效应，提高了重建音频的质量．这一模型适用于可变码率、高保真的音频压缩和发音速度、音调的调整．