Do multiple cycles of aeolian deposit-pedogenesis exist in the reticulate red clay sections in southern China?

Since the Quaternary scientists successfully dis-closed the paleoclimatic significance of the loess-paleo- sol sequence in the Loess Plateau, Northwest China, the loess-paleosol sequence has become well-known terres-trial materials revealing the multiple cyclic changes of Quaternary climates. As a carrier of paleoenvironmental information, it could compare beauty with the deep ocean deposit[8]. In recent years, however, the researchers began to put their sights to southern China. They try t…     

The age of formation of the mirabilite and sand wedges in the Hexi Corridor and their paleoclimatic interpretation

The Hexi Corridor is located at the transition zone of the Asian summer monsoon and westerly airflow, and lies in an important position in terms of its ecological fragility and climatic sensitivity. During a recent field expedition to this region, we found a sedimentary mirabilite layer in a number of localities including Suwushan, Yanchi, Baitujing, Yanchi Gaotai, Huahai, Yumen, Halanuo扙r, and Dunhuang (Fig. 1), which have the potential to provide important information about environmenta…     

Temperature variations on the Tibetan Plateau over the last two millennia

The paleoclimate data recovered from ice cores,tree rings and lake sediments indicate regional features of cfimatic change on the Tibeta n Plateau (TP) during the last 2000 years. The composite temperature reconstructions in-dicate that several main climatic episodes, such as the “LittleIce Age“ between 1400 and 1900, the “Medieval Warm Pe-riod“ in 1150-1400, a less warm period in 800-1100, and an earlier cold period between the 3rd and 5th centuries,occurred in the TP. In addition, temperature varied from region to region. The period from AD 800 to 1100, which waswarm in northeastern TP, was contemporaneous with cool-ing in the western and southern TP. The southern TP ex-perienced warming between 1150 and 1400. For western TP,the δ^18O records of the Guliya ice core indicate that the pe-Hod 1250-1500 witnessed a clear warming. Large-scaletrends in the temperature history from northeastern TP aremore similar to those in eastern China than are the trendsfrom the Guliya ice cap far to the west and southern TP. The most prominent similarities between the temperature varia-tions of the TP and eastern China are such cold phases as 1100-1150, 1500-1550, 1650-1700 and 1800-1850, andthe latter three cold events match with three widespreadg lacial advances which occurred on the TP during the Little Ice A2e.     

Time-division phase modulated single-photon interference in a Sagnac interferometer

We introduce a stable, long-distance singlephoton Sagnac interferometer, which has a balanced configuration to efficiently compensate phase drift caused by change of the fiber-optic path. By using time-division phase modulation, single-photon interference was realized at 1550nm in a 5-km-long as well as 27-km-long Sagnac fiber loops,with a fringe visibility higher than 90% and long-term stability. The stable performance of the single-photon interference indicated that the time-division phase-modulated Sagnac interferometer might readily lead to practical applications in single-photon routing and quantum cryptography.     

Loess-soil sequences in southern Anhui Province： Magnetostratigraphy and paleoclimatic significance

Two parallel loess-soil sequences from Xuancheng and Fanchang in southern Anhui Provinces are dated using geomagnetic and luminescence methods.The Brunhes/Matuyama(B/M) reversal boundary is recognized within the lower part of the so-calles Vermiculated Red Soil (VRS) in the Xuancheng section while the entire Fanchang sequence is of Brunhes age.This indicated that the most recent VRS in southern China,a stratigraphic marker and an indication of extremely warm-humid conditions,was formed during the middle Pleistocene,chronologically correlative with the S4 and S5 soil units in northern China.Microscopic and sedimentologic in vestigations reveal that eolian deposition started in this region at about 0.85 MaBp,roughly synchronous with the well-known Mid-Pleistocene climate change of global significance.The strengthening of both summer and winter monsoon circulations and the consequent river hydrological changes at that time would have provided favorable conditions for sustained eolian deposition in the middle-lower reaches of the Yangtze River since 0.85 MaBP.     

Expression of human clotting factor Ⅸ mediated by recom- binant lentiviral vector in cultured cells and hemophilia B mice

To explore the expression of human clotting factor Ⅸ (hFⅨ) cDNA in vitro and the feasibility of gene therapy for hemophilia B mice mediated by recombinant lentiviral vector, a recombinant hFⅨ lentiviral vector driven by ubiquitin-C promoter, FUXW, and by ABP liver specific promoter, FAXW, was constructed respectively. Recombinant lentivirus was harvested from 293T cells by calcium phosphate-mediated transient cotransfection of three plasmids (transgene vector, CMV腞8.2, VSV-G). hFⅨ expression was detected in supernatant of 293T, BHK and L-02 cells infected with FUXW virus, whereas higher expression of hFⅨ levels (630 ng/106 cells/48 h) was detected only in L-02 cells infected with FAXW virus. Serum hFⅨ antigen was detected in all hemophilia B mice treated with FAXW virus by tail vein injection, an efficiency level of hFⅨ was observed (45 ng/mL, approximately 1% of normal human levels), the expression lasted for more than 60 d. The results indicated that HIV-based lentiviral vectors offer a promising approach to the gene therapy of hemophilia B.     

对甲苯磺酸催化合成丁酸异戊酯

对甲苯磺酸作为丁酸异戊醇的酯化催化剂,性能优于硫酸,本文探讨并确定了丁酸与异戊醇酯化反应的最佳条件:以0.2mol正丁酸为基准,醇酸摩尔比为1.5,环己烷7.5ml,催化剂用量2.5％,反应时间2小时,酯收率达94.3％。     

内燃机缸套-活塞系统摩擦学与动力学行为耦合分析

建立了内燃机缸套—活塞系统油膜润滑与动力学行为的耦合分析模型，并用数值方法对单缸四冲程内燃机进行了仿真分析。在分析中同时考虑了活塞二阶运动和缸体振动对缸套—活塞间油膜润滑的影响。缸体结构振动响应用有限元法来计算，缸套和活塞间的流体润滑计算通过有限差分法求解平均雷诺方程进行，其中考虑了微凸体接触的作用。在考虑缸套—活塞油膜润滑与缸体结构振动、活塞二阶运动耦合作用的情况下，计算出了缸套—活塞间润滑油膜的最小油膜厚度、摩擦力、摩擦功耗等，同时也分析了活塞二阶运动的变化。通过与不考虑缸体振动时的相应结果对比表明：考虑缸体的结构振动后，缸套—活塞间的摩擦力和摩擦功耗减小，油膜厚度、活塞的二阶运动位移及速度增大。     

纳米复合Ti(C,N)基陶瓷烧结晶粒长大的特性

利用材料热力学原理，推导出纳米复合Ti(C，N)基金属陶瓷烧结过程中，晶粒生长速度与大、小颗粒半径之间的关系，并结合实验结果进行了分析．结果表明：纳米复合金属陶瓷在烧结的开始阶段，大晶粒的长大速度呈加速趋势，当大晶粒长大到一定程度时，其长大速度达到最大值，随后，速度逐渐减慢．采用放电等离子烧结、脉冲烧结等方法有可能进一步减小小颗粒的半径．Mo、WC、TiN的加入，抑制了沉淀—析出过程的进行，对晶粒的长大有一定的抑制作用．