Holocene lake deposits of Bosten Lake, southern Xinjiang, China

A 9.25-m-long sediment core from Bosten Lake,Xinjiang, provides detailed information about changes in the water budget and biological acticity over the last 8400 cal-endar years. The chronology is constructed from six AMS radiocarbon dates on the terrestrial plant remains. Based onanalyses of TOC, CO3, detrital compounds and biogenic SiO2,lake level fluctuations and periods of remarkably-negative water budget appeared at 8.4-8.2 cal ka, 7.38-7.25 cal ka,5.7-5.5 cal ka, 3.7-3.4 cal ka and 3.3-2.9 cal ka, respec-tively. As they are in-phase with low lake levels at Sumxl Co and Bangong Co in western Tibet Plateau and with paleo-lakes in Inner Mongolia, a climate-induced change to some-what drier and warmer conditions is inferred. A further drop in lake level after 1320 AD of about 200 yr duration may heattributed to a negative water balance prior to the main phase of the Little Ice Age. Deep and stable lake phases of 1500 yr and 1800 yr duration at 7.2-5.7 cal ka and 5.5-3.7cal ka coincide with maximum moisture during the Holocene Megathermai in China. The long term trend towards aridity since about 4.3 cal ka can dearly be recognised. The reduced water budget of Bosten Lake from 640-1200 AD may be attributed to local effects.     

Palynological records of environmental changes in the middle part of Inner Mongolia,China

Today, the central part of Inner Mongolia has a continental climate, with cold winters, hot summers, and approximately 70% of the precipitation falling in the summer months. Vegetation is dominated by steppe vegetation with Stipa bungeana and Stipa breviflora. Scattered individuals of Quercus liaotungensis, Populus davidiana, Betula platyplylla are distributed in the mountains, with some Pinus tabluaoformis, near Miaoyu, and with fragmentary Picea above 1700—1800 m a.s.l. The Huitenglian…     

Late Glacial and Holocene vegetation history and paleoclimate of the Tengger Desert,northwestern China

With a total area of 36000 km2, the Tengger Desert is the fourth largest desert in China. The Qilian Mountains demarcate the southwestern boundary of the desert andthe Helan Mountain on the east separates the desert from the Mo Us Desert. The Yabulai Mountain on thenorthwest borders the Tengger Desert and the BadainJaran Desert and the Loess Plateau touch its southern tip (Fig. 1). Climatically, the area is situated at the junction of the hyper-arid northwest, the arid to semi-arid sou…     

Speculation on the timing and nature of Late Pleistocene hunter－gatherer colonization of the Tibetan Plateau

1 Human biogeography on the edge The Qinghai-Tibetan Plateau occupies nearly 1.25 million km2 of the Asian continent and reaches an average elevation of more than 4000 m a.s.l. (Fig. 1). In addition to playing a critical role in global climate systems[1,2], the plateau is distinguished as the largest continuous high elevation ecosystem on the planet. This harsh, barren Fig. 1. Map of the Qinghai-Tibetan Plateau (left) and an elevation cross-section from the Badanjaran Desert in the n…     

Reference benchmarks relating to great groups of genetic soil classification of China with soil taxonomy

Soil classification forms the basis for the ex-change and extension of research findings in soil science and for the modernization of management of soil resources. This paper systematically reviews the compatibility of the genetic soil classification of China (GSCC) and soil taxonomy (ST). This includes a study of the evolution and consummation of the GSCC and assessment of the databases and methods of the study. Using the 揝oil Species of China (six volumes) and some provincial soil species as the basic material, the authors gathered information from 2540 soil species. Based on the key described in ST, the 2540 soil species were taxo-nomically classified into corresponding soil orders, suborders, great groups and subgroups and then matched with corre-sponding map units in the 1︰1000000 digital soil map of China. Using the high-level classification units of the two soil classification systems, and the attributes of each soil species, the sizes of distribution areas were mapped. The soil distri-bution results were analyzed and compared statistically. The reference compatibility between the great groups used in GSCC system and the soil orders of the ST is discussed. It is believed that 20 great groups display maximum referencibil-ity >95% and 15 great groups depict maximum referencibil-ity in the range of 70%—95%, which can be cited as refer-ence benchmarks. The remaining 25 great groups are less compatible (with maximum referencibility <70%) and need further study, or require referencing at lower classification levels or at a regional level to help to improve the accuracy of the reference.     

Effect of 5′-deletion ofArabidopsis profilin2 promoter on its vascular specific expression

Based on the published sequence of profilin2 promoter ofArabidopsis thaliana, a full-length promoter (1667 bp) was amplified by PCR. The 5′-end deletion fragments with length of 1380, 1153, 969 and 597 bp were then fused withgus (uidA) gene respectively. Constructed plant expression vectors were individually transferred intoKalanchoe laciniata and transgenic plants regenerated. GUS histochemical assay confirmed that the full-length promoter Pfn1.7 was vascular-specific. Deletion assays showed that profilin2 promoter could be divided into three parts. Deletion of fragment 1 (−1667—−1380 bp) resulted in constitutive expression, suggesting that element(s) responsible for vascular-specific expression might exist in this region. Fragment 2 located at −1153—−597 bp strongly inhibitedgus gene expression. Fragment 3 (−597—−1 bp) is considered as a basic domain of profilin2.     

Simulation study of discharge processes in thunderstorm

The discharge characteristics in thunderstorm have been calculated by using a numerical cloud model. The results indicate that discharge processes occur when simulated thunderstorm developed at the stage of 30-45 min and initial locations of discharge mainly distributes between 4.4-4.8 km and 6.4-6.8 km above the ground (corresponding to ambient temperature of - 10℃ and -25℃. In simulated thunderstorm with a tripole electric structure, 10% of discharges occur between upper positive charge area and middle negative charge area and propagate upwards (from middle negative charge area to upper positive charge area); while, 90% of discharges occur between lower positive charge area and middle negative charge area and propagate downwards (from negative charge area to lower positive charge area). There is a positive correlation between updraft and discharge. The occurrence of discharge process needs hydrometer with a specified concentration and size in cloud (corresponding to ≥ 5 mm/h for precipitation on the ground). The maximum value of precipitation lags the peak of discharge number by a period of about several minutes. The discharge and its variation in thunderstorm are an important factor for monitoring and forecasting thunderstorm.     

High precision topographic data on Lop Nor basin＇s Lake ＂Great Ear＂ and the timing of its becoming a dry salt lake

High precision elevation measurements using DGPS were carried out along three representative tran-sects for the ＂Great Ear＂ area, a dry salt lake within the Lop Nor basin. Results indicate that the Lop Nor basin is only 5.2 m deep and its lowest point occurs at the center of the ＂Great Ear＂. In addition, the basin is asymmetric-steeper in the southwest （0.19‰） and gentler in the northeast （0.09‰）. Points along the same ＂Great Ear＂ ring were found to have an identical elevation value, but different when from different ones （lower towards the center）. The spacing of the ＂Great Ear＂ rings was found to be closely related with the surface steepness. The closer the ＂Great Ear＂ rings are spaced, the steeper the ground surface, and vice versa. These findings support the argument that the ＂Great Ear＂ rings are the former shoreline trails left behind by Lop Nor water during the last few episodes of recession towards its total dry up. A comprehensive analysis of the high precision elevation data, historical accounts, aerial and satellite photographs and imagery, and official topographic maps of the study area suggests that the ＂Great Ear＂ area in the Lop Nor basin was incorrectly mapped as being covered by a great body of water on the 1963 topographic maps. A re-interpretation of the 1958 aerial photographs and newer remote sensing imagery indicated that the ＂Great Ear＂ ring structure was already in place in 1958 and it continued to appear on the subsequent remote sensing data without any major changes. It is estimated that lake water in the ＂Great Ear＂ area of the Lop Nor basin disappeared between the late 1930s and early 1940s.     

A high-resolution climatic chanse since Holocene inferred from multi-proxy of lake sediment in westerly area of China

Multi-proxy data are presented and a discuss is made of paleoclimatic and paleoenvironmental changes during Holocene from a 225-cm-long sediment core from Wulungu Lake, located in westerly area of China. The chronology is constructed from six AMS radiocarbon dates on the bulk organic matter. Analyses of pollen, TOC, TN, δ^13Corg, ostracod assemblages and the shell stable isotopes, suggest Holocene climate pattern as follows： temperate and dry （10.0-7.6 cal. ka BP） -warm and wet （7.6-5.3 cal. ka BP） -warm and moist （5.3-3.6 cal. ka BP） -temperate and dry （3.6-2.1 cal. ka BP）-temperate and moist （2.1-1.3 cal. ka BP） -cool and dry （1.3 cal. ka BP-present）. With the climatic change, Wulungu Lake experienced two large-scale retreat （5.3-3.6 cal. ka BP and 1.3 cal. ka BP-present） and an obvious transgression （7.6-5.3 cal. ka BP）. The records of climatic and environmental evolution of Wulungu Lake were in good accordance with those of adjacent areas. It responded to regional environmental change, global abrupt climate events and followed the westerly climate change mode.     

When and how did plate tectonics begin？ Theoretical and empirical considerations

Plate tectonics is the horizontal motion of Earth’s thermal boundary layer (lithosphere) over the convecting mantle (asthenosphere) and is mostly driven by lithosphere sinking in subduction zones. Plate tectonics is an outstanding example of a self organizing, far from equilibrium complex system (SOFFECS), driven by the negative buoyancy of the thermal boundary layer and controlled by dissipation in the bending lithosphere and viscous mantle. Plate tectonics is an unusual way for a silicate planet to lose heat, as it exists on only one of the large five silicate bodies in the inner solar system. It is not known when this mode of tectonic activity and heat loss began on Earth. All silicate planets probably experienced a short-lived magma ocean stage. After this solidified, stagnant lid behavior is the common mode of planetary heat loss, with interior heat being lost by delamination and “hot spot” volcanism and shallow intrusions. Decompression melting in the hotter early Earth generated a different lithosphere than today, with thicker oceanic crust and thinner mantle lithosphere; such lithosphere would take much longer than at present to become negatively buoyant, suggesting that plate tectonics on the early Earth occurred sporadically if at all. Plate tectonics became sustainable (the modern style) when Earth cooled sufficiently that decompression melting beneath spreading ridges made thin oceanic crust, allowing oceanic lithosphere to become negatively buoyant after a few tens of millions of years. Ultimately the question of when plate tectonics began must be answered by informa- tion retrieved from the geologic record. Criteria for the operation of plate tectonics includes ophiolites, blueschist and ultra-high pressure metamorphic belts, eclogites, passive margins, transform faults, paleomagnetic demonstration of different motions of different cratons, and the presence of diagnostic geochemical and isotopic indicators in igneous rocks. This record must be interpreted individually; I interpret the record to indicate a progression of tectonic styles from active Archean tectonics and magmatism to something similar to plate tectonics at ~1.9 Ga to sustained, modern style plate tectonics with deep subduction——and powerful slab pull——beginning in Neoproterozoic time.     

利用γ-丁内酯衍生物研究空泡化与细胞分化

从化学遗传学的角度,利用γ-丁内酯衍生物研究了成纤维细胞生长因子（fibroblast growth factor, FGF）诱导鸡胚盘细胞向血管内皮细胞分化过程中,空泡化对血管内皮细胞分化的影响。中性红染色及吖啶橙染色结果表明,在血管内皮细胞分化过程中出现的膜泡为酸性膜泡,γ-丁内酯衍生物可能通过抑制这些酸性膜泡,抑制了鸡胚盘细胞向血管内皮细胞的分化。该研究结果进一步证实了空泡化在细胞分化中的作用,并为研究γ-丁内酯衍生物的靶蛋白在鸡胚盘细胞向内皮细胞分化中的作用打下了基础。     

Carbon isotopic compositions of individual terpenoids in heavy oils from Karamay oilfield

The carbon isotopic compositions of individual terpenoids in the heavy oils from the Karamay oilfield were determined by using the method of enrichment of terpanes with molecular sieve 13X and GC-IRMS technique. The terpanes, selectively enriched from the biodegraded oils with molecular sieve 13X, can meet the demand of GC-IRMS analysis. The carbon isotopic compositions of the hopanoids (δ13C -31.7‰--37.8‰ ) infer that their main source is probably non-methanotrophic bacteria, and that the depositional environment of source rocks is a strongly reductive, rapidly depositional, and closed-semi-closed saline lagoon.     

Lower Cambrian phosphatized Punctatus from southern Shaanxi and their ontogeny sequence

Phosphatized and three-dimensionally preserved embryos and spherical fossils of metazoan recovered from the Kuanchuanpu Member, Dengying Formation in southern Shaanxi, China provide nice devel- opmental sequence for the studies of origination, taxonomy, phylogenic evolution and developmental biology of early animals. Ontogeny of these larva fossils has not been systemically studied mainly due to their poor preservation and limited identification. The Kuanchuanpu Member, predominated by phosphorites and cherts, yields phosphatized animal embryos, particularly those of Olivooides and Punctatus which have high resolution in fine structures and different ontogeny developmental stages. An ontogenetic sequence of the Punctatus is established mainly base on its developmental transitions from body part to oral one, which is perfectly consistent with the embryonic ontogeny sequence pro- posed by Bengtson and Yue (1997). Furthermore, a new genus Quadrapyrgites gen. nov is erected to receive a larva with tetraradial body plan.     

Mining Representative Subset Based on Fuzzy Clustering

Two new concepts-fuzzy mutuality and average fuzzy entropy are presented. Then based on these concepts, a new algorithm-RSMA （representative subset mining algorithm） is proposed, which can abstract representative subset from massive data. To accelerate the speed of producing representative subset, an improved algorithm-ARSMA（accelerated representative subset mining algorithm） is advanced, which adopt combining putting forward with backward strategies. In this way, the performance of the algorithm is improved. Finally we make experiments on real datasets and evaluate the representative subset. The experiment shows that ARSMA algorithm is more excellent than RandomPick algorithm either on effectiveness or efficiency.     

Variation of δ13C in karst soil in Yaji Karst Experiment Site, Guilin

This study deals with δ₁₃ C variation in karst soil system of Yaji Karst Experiment Site, Guilin, a typical region of humid subtropical karst formations. Samples of near ground air, plant tissue, soil and water (soil solution and karst spring) were respectively collected on site in different seasons during 1996–1999. Considerable variation of δ₁₃ C values are not only found with different carbon pools of soil organic carbon, soil air CO₂ and soil water HCO₃⁻, but also with the soil depths and with different seasons during a year. The °₁₃ C values of CO₂ both of near ground air and soil air are lower in July than those in April by 1‰–4‰ PDB. Our results indicate that the δ₁₃ C values of carbon in the water and air are essentially dependent on interface carbon interaction of air-plant—soil-rock—water governed by soil organic carbon and soil CO₂ in the system.     

Quantum chemical and topological study on the insertion reaction of dichlorcarbene with acetaldehyde

The insertion reaction mechanisms of siglet and striglet CCI2 with CH3CHO have been studied by using the DFT, NBO, CCSD（T） and AIM method. The geometries of reactions, transition state and products were completely optimized by B3LYP/6-31G（d）. All the energy of the species was obtained at the CCSD（T）/6-31G（d,p） level. The calculated results indicated that all the major pathways of the reaction were obtained on the singlet potential energy surface. The singlet CCl2 can not only insert the Cα--H （reaction I） but also can react with Cβ--H （reaction ll）. There are three main existing pathways and the products are P1 （CH3COHCCl2）, P2 （CH2COHCHCl2） and P4[CHCl2CHCHOH] respectively. Reaction II happens more easily according to the energy changes and the barrier in rate-controlling step. In addition, the important geometries in domain pathways have been studied by AIM theory. And also, the energy changes of H in the inserted C--H bond have been investigated.     

NMR and IR investigations of ternary inclusion complexes among β-cyclodextrin, rare earth metal ions, and naphthalenediamines

Ternary inclusion complexes β-cyclodextrin (β-CD), rare earth metal ions (YbCl₃, YCl₃), and 1,8-naphthalene- diamine/1,5-naphthalenediamine are synthesized in basic aqueous media, which are characterized via ¹H NMR and IR spectroscopy. The stoichiometric proportion of β-CD:YbCl₃:1,5-naphthalenediamine is 2:1:2, that of β-CD:YCl₃:1,8-naphthalenediamine is 2:1:1, and that of β-CD:YbCl₃:1,8-naphthalenediamine is 2:1:1. The IR spectroscopy of the ternary inclusion complexes in the range of 935–1 000 cm⁻¹ reveals the existence of the coordinate bond M—O or M—N. The possible conformations of the ternary inclusion complexes are depicted. Biography: JIANG Huiming(1972–), male, Associate professor, research direction: molecular complex chemistry, supramolecular chemistry.     

New crystal structure of molecular complex 1-piperidine carboxylate-piperidinium-H<Subscript>2</Subscript>O studied by X-ray single crystal diffraction

Piperidine absorbs CO2 and H2O in air to form a molecular complex： piperidium-l-piperidinecarboxylate-H2O. The structure of the complex was characterized by X-ray single crystal diffraction. The crystal structure was determined to be triclinic, space group P1^-with a=0.648 6（8） nm, b=0.809 200） nm, c= 1.357 1（16） nm, a=96.96706）°, β =102.506（15）°,γ=104.202 05）°, Z=2. The complex is stabilized via five hydrogen bonds between the three components, N-O electrostatic interaction and O-O interaction （electron transfer） betweenl-piperidinecarboxylate and H2O. Due to electron transference of carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the O-H bond is considerably shorter than that of the free molecule of water. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.     

Eigenvalues, inequalities and ergodic theory

This paper surveys the main results obtained during the period 1992—1999 on three aspects mentioned in the title. The first result is a new and general variational formula for the lower bound of spectral gap (i.e. the first non-trivial eigenvalue) of elliptic operators in Euclidean space, Laplacian on Riemannian manifolds or Markov chains (§ 1). Here, a probabilistic method — coupling method is adopted. The new formula is a dual of the classical variational formula. The last formula is actually equivalent to Poincaré inequality. To which, there are closely related logarithmic Sobolev inequality, Nash inequality, Liggett inequality and so on. These inequalities are treated in a unified way by using Cheeger’s method which comes from Riemannian geometry. This consists of § 2. The results on these two aspects are mainly completed by the author joint with F. Y. Wang. Furthermore, a diagram of the inequalities and the traditional three types of ergodicity is presented (§ 3). The diagram extends the ergodic theory of Markov processes. The details of the methods used in the paper will be explained in a subsequent paper under the same title.