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

The characteristics of the modern monsoon climate o?China may be used as clues for recognizing the records of paleomonsoon climate. The present paper deals primarily with the various paleomonsoon records of the last 130,000 years in the southeast monsoon area. These records mainly come from the following three fields: (i) the historical, (ii) the geological, including loess-paleosol sequence, deserts, lakes, snowlines, timberlines, the phenomena of continental desertization and so on, and (iii) the biological, presented by vegetation and mammals. Among these records, the loess-paleosol sequence in the Loess Plateau reflects a climatic history characterized by alternation of two different climatic periods when the Asian winter monsoon and summer monsoon showed pronounced effects on environment, respectively.     

AN EXPERIMENTAL SIMULATION ON FORMATION OF SUMMER MONSOON CIRCULATION OVER ASIA——IMPORTANT ROLE OF CROSS-EQUATORIAL CURRENT

In the experimental simulation carried out in a rotating annulus of stratified fluid, theeffects of the cross-equatorial current over the West Indian Ocean, the Tibetan Plateauand different thermal factors have been included according to the similarity requierements.and thus the Asian summer monsoon circulation systems, such as the SW monsoon current,the Indian monsoon depression, the monsoon trough, the Iran high and the shear line overSouth China in the lower-middle layer, and the Tibetan high and easterlies over South Asiain the upper layer, have been well simulated. The experimental results show that the cross-equatorial current over the West IndianOcean plays a key role in the formation of the Asian monsoon systems. The SW monsoonis directly and originally evolved from it. In addition, together with the NE current inthe southeastern part of the Iran high, it composes the cyclonic shear flow situation, andthus provides an important background for the formation of monsoon depression. Underthese conditions, the latent heat of rainfall and the cooling effect over the surface of theArabian Sea can cause the Indian monsoon depression to further develop. According tothe experimental results in different cases, this paper also sheds light on some of the fun-damental mechanism of monsoon systems.     

ON THE ABRUPT CHANGE IN SOUTH ASIAN SUMMER MONSOON CLIMATE AND ITS SYNCHRONISM WITH THE GLOBAL RAPID WARMING

This paper has analysed the major characteristics of long-term variation, of summermonsoon climate in South Asia since 1888. An abrupt enhancement of summer monsoon inthe 1920s and its synchronism with the global rapid warming have been detected by theMann-Kendall Rank Statistic test. Based on diagnostic analysis on the atmospheric circulationover the monsoon region and the thermal conditions of both ocean and land during theperiod of abrupt change, it is found that the warming over land was stronger and earlierthan that over the ocean, which would enhance the land-sea thermal contrast and thereforebe favorable to the development of monsoon low and the disturbance in the monsoon flow.This may be a direct factor for the abrupt enhancement of summer monsoon.     

AN EXPERIMENTAL SIMULATION ON THE MECHANICAL EFFECT OF TIBETAN PLATEAU ON ZONAL CIRCULATION OF STRATIFIED ATMOSPHERE

The present work is intended to simulate, in a rotating annulus of stratified liquid, the me-chanical effect of the Xizang (Tibetan) Plateau on the zonal circulation. The main featuresof three flow patterns around the plateau for different Rossby number R and rotating Eulernumber E are analysed. and a division diagram of the flow pattern in (R, E) plane is given.It has been found that under the condition that similarity criterions R and E of the experimentalfluid are the same as those existing in the atmosphere for monthly mean states in spring, au-tumn and winter months, the experimental results are satisfied for the following weathersystems over the plateau and its vicinities: the low vortex, trough and shear line over thesoutheast part of the plateau, the tilted ridge over the northwest part of the plateau, the troughpatterns over the upstream and dewnstream of the plateau, the vertical circulation structure, thejets on both north and southeast sides of the plateau, and so on. This shows that the mec     

Preferential Oxidation of CO in Excess Hydrogen over CuO-CeO2 Catalyst Prepared by Chelating Method

The CuO-CeO2 catalyst prepared by chelating method has a superior catalytic performance for the preferential oxidation of CO in rich hydrogen, compared with the CuO-CeO2 catalyst prepared by coprecipitation method. The CO conversions over these catalysts, at 120℃and 120000 ml/(g-h) in the absence of CO2 and H2O, are 99.6% and 88.6%, respectively, and the selectivity of O2 over these catalysts is very close (i.e. 51.3% and 55.8%, respectively). The influence of certain factors such as hydrogen concentration, carbon monoxide concentration, H2O, O2/CO ratios, and space velocity on the catalytic performance of CuO-CeO2 catalyst prepared by chelating method is also studied. The results show that the addition of hydrogen and H2O has a negative effect on the catalytic performance of CuO-CeO2 catalyst, however, the variation of space velocity and the O2/CO ratio causes a comparatively slight influence.     

A Dynamic Analysis and Numerical Simulation of Explosive Development of an Extratropical Cyclone Over Land

The present paper has made a dynamic and diagnostic study of the process of explosive deepening of an extratropical cyclone over North China on April 25-26, 1983, in order to gain an insight into the physical mechanism of explosive development of cyclone over land. It turns out that this cyclone occurred in the strong baroclinic zone, and the vorticity and thermal advection triggered the initial development of the cyclone. Subsequently, as the rainfall increased, the effect of condensational heating became more and more important. During the time period of rapid intensification (from 1200GMT 25 to 0000GMT 26 April, 1983, the central surface pressure fell down from 998. 2 to 988. 3 hPa), the peak of diabatic heating profile continuously descended, leading to a rapid increase in heating amount in the lower troposphere. This condition is favorable to the explosive development of rotational circulation or vortex. The numerical simulations have further demonstrated the importance of the lowering of heating p     

EFFECT OF THE COMPOSITION OF m-CRESOL/H2O SOLVENT ON HYDRODYNAMIC PROPERTIES OF NYLON 6

The intrinsic viscosity [ η], Huggins constant (KH), [ η]0, α3 and flow activation energy values of nylon 6 have been measured in water/m-cresol (0/100-20/80) systems at different temperatures (20-60℃). It has been found that the intrinsic viscosity, [η]0 and α3 increase with the increase in water contents in m-cresol up to 15% and then decrease. They increase with the increase in temperature irrespective of solvent composition. It has been noted that the percent increase of α3 is the highest at 60℃ and the lowest at 20℃ for a particular solvent system. The intrinsic viscosity data obey Arrhenius equation over the considered conditions. The activation energy and the KH values decrease very sharply with the addition of water,giving a minimum value at 15% of water and then increase slowly. The variation of all the parameters has been explained in terms of variation in thermodynamic quality of solvent with the addition of water to m-cresol and change in temperature,resulting in the change of conformational and orientational properties of polymer molecules. This change of solvent quality also results in variation of selective sorption of solvent over the polymer, such as hydrogen bonding, etc.     

NON-LINEAR DYNAMIC INSTABILITY OF TWO DIMENSIONAL SLAB SYMMETRIC DISSIPATIVE DISTURBANCES ON ROTATING EARTH

The non-linear instability of the two-dimensional slab symmetric disturbances of the dis-sipative system on the rotating earth subject to the forcing of the mean temperature field isinvestigated by means of the 5 modes low order truncated spectrum. We get the catastropheof the butterfly type. For a given definite value to the horizontal temperature gradient, withthe decrease of the static stability, the equilibrium state of the system generally proceeds start-ing from a quiescent single stable state, then abruptly jumping to the single stable state witha circulation of a certain strength, hereafter again residing stably in the double stable state ofstrong circulation. Moreover, there does not appear the periodic and non-periodic variation.Without temperature gradient, only a definite and comparatively weak vertical eddy viscosityin conjunction with the non-linear mechanism of the system itself and the linear static insta-bility of the environment can lead to the periodic or non-periodic variation.     

STABILITY OF TETRANUCLEAR EARLY TRANSITION —METAL CLUSTERS

<正> The bonding capacities of tetranuclear early transition-metal clusters have been estimated based on the extended Huckel calculations.Using the Walsh diagram which shows orbital levels during the variation in geometry,a method has been established to determine their stability which is described with three factors:the symmetry and geometrical size,the distribution of ligands,and the number of cluster core electrons(CCEs).The stabilities of many cluster compounds can be successfully explained.     

A New Triterpenoid Saponin from the Seeds of Deccaria segetalis

The seeds of Vaccaria segetalis (Neck) Garcke, which is distributed all over China,except southern China, are used in Chinese folk medicine for promoting diuresis,activating blood circulation and relieving carbuncles 1. Previous studies on the seeds ofthis plant have led to the isolation of seven cyclic peptides 2-5 and several saponins 6-]o.We have repoyted the isolation and structural elucidation of Segetosides A, C-E from theseeds of Vaccaria segetalis I I-13. FuFther investigation of…     

镍氢电池的循环性能与活性物质微结构的研究

与循环试验大致同步, 用静态(初态和终态)或准动态(增加若干个中间态)的模式对MH/H电池循环性能、电极(包括负极和正极)材料的微结构进行了X射线衍射(XRD)研究, 发现循环性能衰减与正极材料β-Ni(OH)₂的点阵参数、平均晶粒尺度、微应变和总的层错几率均随循环周期增加而减小以及负极材料中腐蚀产物A(OH)₃和B相出现和增加有一定的对应关系, 发现MH/Ni 电池循环性能的衰减是正极材料和负极材料的结构和微结构随着循环次数的增加发生明显变化, 恶化了正负极材料的电化学性能, 同时消耗和恶化了电解液的综合结果. 为了提高电池的循环性能, 采用不同正极材料的添加剂. 结果表明, CaF₂和Lu₂O₃有明显的效果, 其中CaF₂效果最好, 并有广泛的实用性.     

Occurrence,evolution and degradation of heavy haze events in Beijing traced by iodine-127 and iodine-129 in aerosols

Heavy haze events have become a serious environment and health problem in China and many developing countries, especially in big cities, like Beijing. However, the factors and processes triggered the formation of secondary particles from the gaseous pollutants are still not clear, and the processes driving evolution and degradation of heavy haze events are not well understood. Iodine isotopes (¹²⁷I and ¹²⁹I) as tracers were analyzed in time series aerosol samples collected from Beijing. It was observed that the ¹²⁷I concentrations in aerosols peaked during the heavy haze events. The conversion of gaseous iodine to particular iodine oxides through photochemical reactions provides primary nuclei in nucleation and formation of secondary air particles, which was strengthened as the external iodine input from the fossil fuel burning in the south/southeast industrial cities and consequentially induced heavy haze events. Anthropogenic ¹²⁹I concentrations peaked during clean air conditions and showed high levels in spring and later autumn compared to that in summer. ¹²⁹I originated from the direct air discharges and re-emissions from contaminated seawaters by the European nuclear fuel reprocessing plants was transported to Beijing by the interaction of Westerlies and East Asian winter monsoon. Three types of mechanisms were found in the formation and evolution of heavy haze events in Beijing by the variation of ¹²⁷I and ¹²⁹I, i.e., iodine oxides intermediated secondary air particles, dust storm and mixed mode by both secondary air particles and dust storm induced processes.     

Reversible and irreversible variation of the superstructure of highly oriented low-density polyethylene during heat treatment

The small-angle x-ray scattering (SAXS) intensity of highly-oriented, low-density polyethylene (LDPE) with fixed draw ratio has been investigated during several heating and cooling cycles. Using a three-dimensional, monoclinic, paracrystalline superlattice to describe the superstructure of the sample, it has been possible to calculate the SAXS patterns completely. A very large irreversible variation of the superstructure during the first heating cycle, and a smaller reversible variation of the average size and distance of the crystallites during subsequent temperature cycles, could be obtained. These results can be explained using the thermodynamic theory of crystallization of polymer multicomponent systems of Kilian.     

Beryllium-7 in near-surface atmospheric aerosols in mid-latitude (40°N) city Beijing, China

A high-volume air sampler and a high-resolution gamma-ray spectrometer have been used to measure the activity of ⁷Be in near-surface atmospheric aerosols at sampling frequency of 3 days week for 1 year from August 2009 to July 2010 at Beijing in the mid-latitude region of East Asia monsoon. The measurements indicate that the average concentration of ⁷Be was 8.39 ± 0.49 mBq m^?3, which was significantly higher than values reported for other cities in the East Asia monsoon region and in the world during the same period. The maximum and minimum of the weekly means of ⁷Be concentration were observed in September and May, respectively. The ⁷Be concentrations varied in accordance with the monsoon phases. Low but frequent wet precipitation may have caused lower ⁷Be observed in July when southeasterly was prevailing. Higher seasonal mean of ⁷Be concentrations in autumn could be attributed to the abnormal atmospheric circulation in autumn 2009.     

Towards Maintenance‐Free Biosensors for Hundreds of Bind/Release Cycles

A single aptamer bioreceptor layer was formed using a common streptavidin–biotin immobilization strategy and employed for 100–365 bind/release cycles. Chemically induced aptamer unfolding and release of its bound target was accomplished using alkaline solutions with high salt concentrations or deionized (DI) water. The use of DI water scavenged from the ambient atmosphere represents a first step towards maintenance‐free biosensors that do not require the storage of liquid reagents. The aptamer binding affinity was determined by surface plasmon resonance and found to be almost constant over 100–365 bind/release cycles with a variation of less than 5 % relative standard deviation. This reversible operation of biosensors based on immobilized aptamers without storage of liquid reagents introduces a conceptually new perspective in biosensing. Such new biosensing capability will be important for distributed sensor networks, sensors in resource‐limited settings, and wearable sensor applications.     

Anodes for lithium batteries: tin revisited

Pure tin, without the addition of conducting diluents or binders, has been evaluated as an anode in lithium cells. Capacities approaching 600 mAh/g are maintained for over 10 deep cycles, before falling off, indicating the inherent reversibility of the tin anode. These are comparable to those reported for Cu₆Sn₅ and considerably higher than for deposited tin films. The tin grain size was determined and found to decrease with cycling from over 400 to below 100 nm over 10 cycles. The cell impedance increases significantly after 10 cycles, consistent with the observed loss of capacity on extended cycling.     

中国的百岁老人研究Ⅰ.百岁老人的地区分布、性别差异和民族特征

利用全国人口普查资料及部分地区的调查资料,统计分析了百岁老人的百岁比和性别比。结果显示,中国百岁老人存在明显的地区分布不均衡性、性别差异的可变化性,以及民族长寿的特异性。我国至少有4个省和自治区的百岁老人数男性多于女性,有13个民族的百岁老人比例达到联合国规定的长寿之乡标准,这些民族可称作长寿民族。