ISSN 0253-2778

CN 34-1054/N

2009 Vol. 39, No. 7

Display Method:
Geochemical research on prehistorical culture of Yuchisi Site in Mengcheng Ⅱ — Reconstruction of climatic changes and discussion on proxy selection
XU Li-bin, SUN Li-guang, PENG Zi-cheng, LUO Hong-hao, WANG Ji-huai
2009, 39(7): 673-682.
Application of the new methods of palynology, geochemistry and so on can help researches based on the archaeological profile to break free from the disciplinary limitations that beset cultural relic researches, and provide meaningful information for archaeological research. 230 samples were collected from a 460 cm deep sediment profile named YC1 in the Yuchisi Site in Mengcheng, Anhui Province at an interval of 2 cm. The site contains cultural layers of the Dawenkou Culture and Longshan Culture, aged from 5 050 cal.aB.P. to 4 000 cal.aB.P. Based on the statistical analysis of elements and grain size in the cultural layers of Yuchisi Site in Mengcheng of Anhui, the extent of every index responding to human activities and climate was obtained, and the climatic change of Yuchisi Site from 5 050 cal.aB.P. to 4 000 cal.aB.P. was reconstructed using climatic impacting indexes, such as factor2 from Principle component analysis, Al2O3/SiO2 and clay concentration. Results show that the climate in the Dawenkou Culture (from 5 050 cal.aB.P. to 4 400 cal.aB.P.) was quite warm and wet, but in the Longshan Culture (from 4 400 cal.aB.P. to 4 000 cal.aB.P.) it was quite cold and dry. From the comparison with classical Asian monsoon index (Stalagmitic δ8O records in Dongge Cave) and solar activity, the reasons for climatic change, and the correlation between climatic change and cultures in primitive society were discussed. Based on this study, it is recommended that the climatic proxy that is heavily influenced by human activities should be avoided.
Effect of electric field on low-latitude storm time ionospheric foF2 variations
SUN Shu-ji, CHEN Chun, DING Zong-hua, BAN Pan-pan, LIU Yun, XI Di-long
2009, 39(7): 683-687.
The electric field plays an important role in low-latitude ionospheric evolutions. Taking two major storms in October-November 2003 for example, the effects of plasma transportation, which is caused by equatorial disturbance electric field, on low-latitude storm time ionospheric variations at given locations were studied near 105°E. The theoretical model of SAMI2 was used to simulate these two events. It is shown that the electric field can cause complicated variations on the ionospheric foF2. For the isolated storm during 19~24 November, the disturbance field dominated the ionospheric variations during the initial phase. The upward/polarward plasma drift caused a negative storm at Haikou and a positive one at Chongqing and Lanzhou, respectively. The former and the latter two are on either side of the north crest of equatorial ionospheric anomaly. For the seriate storms during 28 October-2 November, the influence of the electric field was major at the beginning, while both the field and the neutral composition act on the ionosphere subsequently, leading to complex disturbances. The disturbance field can cause immediate responses on the ionosphere, though the latter can last longer. The results shown here is of importance to zonal short-time ionospheric predictions.
Analysis of time history responses of engineering structures during earthquakes based on state space theory
SHEN Xiao-pu, CHEN Rong-yi, CHEN Dao-zheng, WANG Jian-guo
2009, 39(7): 688-693.
The engineering structure time history response in earthquakes was analyzed by means of state space theory. The state equations of the engineering structure time history responses were established with the inhomogeneous solutions given on the basis of the structure dynamic equations and the state variables. The Kely-Hamilton method, the state space method and the fine integral method were applied with the corresponding computing format and programs to solve the matrix exponential function. Several numerical examples demonstrate that the state space method has better accuracy and higher efficiency for analyzing structures dynamic time history responses.
Low-frequency internal friction research on La2Cu1-xZnxO4+δ
CHEN Zhi-jun, WU Xiu-sheng, YANG Chun-li, GAO Hai-ying, LIU Wei
2009, 39(7): 694-698.
The low-frequency internal friction Q-1 and relative shear modulus M of La2Cu1-xZnxO4+δ (0≤x≤02) compounds were studied. It was found that for 0≤x≤0005, there are two relaxation internal friction peaks around 200 K and 250 K, which are both due to the hopping of the excess O atoms; while for 005≤x≤02, only one relaxation peak exists around 250 K and this peak is due to the hopping of O pairs. The position of the structure phase transition revealed by shear modulus moves to higher temperature side with the increase of Zn content. In addition, the temperature of relaxation internal friction peaks also increases with the rise of Zn content.
AC electrodeposition frequency dependence of composition and magnetic properties of Fe-Co nanowire arrays
SU Hai-lin, WANG Rui-long, TANG Shao-long, DU You-wei, CHEN Yi-qing
2009, 39(7): 699-705.
Fe-Co alloy nanowire arrays with the interwire distance of about 50 nm and the wire diameter of about 22 nm were fabricated by alternating current electrodeposition at different frequencies into anodic aluminum oxide templates. The influences of the deposition frequency on the composition, crystalline structure and magnetic properties of the arrays were studied in detail. It was found that the deposition frequency for the Fe-Co alloy nanowire arrays has an optimal range of 5~350 Hz. For the arrays prepared within this range, the deposition frequency has no obvious influence on their crystalline structure, while it does affect the arrays composition and magnetic properties. The variations for the nanowires saturation magnetization and the magnetostatic interaction between nanowires were employed to explain the change in the arrays magnetic properties with the deposition frequency qualitatively. After annealing in hydrogen atmosphere, all the arrays fabricated within the optimal frequency range have fairly good magnetic properties. Their coercivities and squarenesses are higher than 3512 kOe and 0939, respectively. The array deposited at 50 Hz possesses the comparatively best hard magnetic performance. The thermomagnetic analysis indicates that its Curie temperature is about 630 ℃.
Inhibition of lung tumor growth in nude mice by siRNA targeting on EGFR
WANG Ben-zhu, LI Yan, ZHANG Hai-yan, WANG Zhe, ZHANG Bi-liang
2009, 39(7): 706-713.
The inhibitory effect of lung tumor growth in nude mice by siRNA targeting on EGFR (epidermal growth factor receptor) was investigated. Three different chemically synthesized small interfering RNAs (siRNAs) targeting on EGFR were utilized to block EGFR gene expression in a human non-small cell lung cancer (NSCLC) cell line A549, which overexpresses the EGFR protein. The results demonstrated that EGFR siRNAs potently suppress the expression of EGFR in A549 cells and the most efficacious siRNA is EGFR siRNA_1. Decreasing EGFR expression can notably increase the apoptosis and inhibit the proliferation of A549 cells. In the end, subcutaneous tumor models were established with luciferase expressing lung cancer cell line (A549-luc), and the tumor growth and bioluminescence were non-invasively monitored by an in vivo imaging system in real time. A quantitative analysis of the tumor luciferase gene spatial expression and tumor volume of different treatment groups showed that the growth velocity of EGFR siRNA_1 treatment group is lower than that of the Notarget siRNA treatment group, indicating that siRNA targeting EGFR can inhibit the lung subcutaneous tumor growth in nude mice.
Isolation, identification and expression analysis of PD-1 gene in Tupaia belangeri
ZHANG Xu-dong, SHAO Xiao-li, ZHANG Yuan-xu, ZHANG Hua-tang, HE You-wen
2009, 39(7): 714-721.
Programmed cell death 1 (PD-1) is an inhibitory receptor that belongs to the immunoglobulin (Ig) superfamily. Numerous studies have demonstrated that PD-1 expression can be induced in activated T lymphocytes, NKT cells, B lymphocytes and monocytes and play a critical role in the pathogenesis of chronic infections. Tupaia belangeri (tree shrew) represents an excellent model for some of the major human infectious diseases such as hepatitis B virus infection. To fully utilize tree shrew as a host immune response model to infectious diseases, tree shrew PD-1 was isolated. Full-length tree shrew PD-1 cDNA was cloned from spleen of tree shrew by rapid amplification of cDNA end-PCR (RACE-PCR). Sequence analysis revealed that the open reading frame (ORF) of tree shrew PD-1 cDNA encoded a predicted transmembrane protein of 242 amino acids with high homology with humans, primates and rodents. Expression of PD-1 in tree shrew was detected in spleen but not in other organs by RT-PCR. Stimulation of freshly isolated tree shrew peripheral blood monouclear cells(PBMCs) with PMA and ionomycin increased the expression of PD-1 mRNA. Our results may provide a foundation for future exploration of tree shrew immune function.
Isolation, identification and expression analysis of interleukin 2 receptor alpha chain (CD25) gene in Tupaia belangeri
SHAO Xiao-li, ZHANG Xu-dong, ZHANG Yuan-xu, ZHANG Hua-tang, HE You-wen
2009, 39(7): 722-727.
CD25 is an important cell surface marker for CD4+CD25+ regulatory T cells (Tregs) and tree shrew is an animal model used in the study of human viral infections. However, the molecular identity of tree shrew CD25 (tsCD25) remains unclear. We cloned tsCD25 and analyzed its expression pattern. A full-length cDNA of tree shrew interleukin 2 receptor alpha chain(tsCD25) gene was obtained from tree shrew spleen by RT-PCR (reverse transcription-polymerase chain reaction). The tsCD25 cDNA contains an ORF of 816 bp, encoding a 309 ku of peptide with a predicted 271 amino acids. The mature tsCD25 peptide contains two Sushi domains, two N-linked and multiple O-linked glycosylation sites. The tsCD25 is very similar to those of primates at the amino acid level, ranging from 653% to 664%. Tissue transcription analysis indicates that tsCD25 mRNA is expressed in peripheral blood, spleen and lung. Lymphocytes expression analysis demonstrates that tsCD25 mRNA is up-regulated by PMA and ionomycin stimulation. Our results may provide a basis for future studies such as generating monoclonal antibodies to tsCD25.
Effect of gravity condition on boiling bubbles
ZHAO Rui, CHENG Wen-long, LIU Qi-nie, FAN Han-lin
2009, 39(7): 728-733.
A model of the boiling bubble was presented based on the bubble dynamics. The characteristics of the boiling bubble were studied under both various gravity conditions and various conductive conditions. The departure diameter and the bubbling frequency of the bubble were obtained. The effect of gravity condition and of conductive condition on the characteristics of the boiling bubble was compared. A correlation between the effect of gravity condition and of conductive condition on the characteristics of the boiling bubble was then concluded. With this correlation, the experimental results of the bubble boiling under the terrestrial condition could be extended analogously to instances under the space condition.
Methane conversion to acetylene under non-equilibrium gliding arc plasma driven by magnetism
ZHAO Yu-han, HE Xian-jun, XIA Wei-dong
2009, 39(7): 734-737.
Gliding arc discharge can provide equilibrium and non-equilibrium plasma in one discharge cycle. It can provide high energy electrons, active electrons, atoms and molecules to enhance the chemical conversion reaction, as well as higher power. Methane conversion to acetylene was performed in the gliding arc reactor at different specific energies and magnetic field intensities. The experimental results show that specific energy and magnetic field intensity can affect the conversion rate of methane, selection and yield of acetylene, and energy consumption of acetylene.
Experimental study on the entrainment mass flow rate across the smoke layer interface during horizontal spread in a long channel
JI Jie, HUO Ran, ZHANG Ying, ZHONG Wei, HU Long-hua
2009, 39(7): 738-742.
Based on the different entrainment mechanisms, the smoke movement in a long channel can be divided into four stages. Small scale experiments were carried out with temperature, thickness and velocity of the smoke layer measured. The transitional states of the four stages were analyzed and determined. The entrainment mass flow rate across the smoke layer interface in the stage of radial spread after impinging onto the ceiling and in the transitional stage it gradually assumes one-dimensional horizontal spread was deduced. Combining the experimental results and theoretical analysis, an empirical formula for predicting the entrainment rate across the smoke layer interface was deduced.
Measurement of effective water mist flux by electronic balance
LIU Yi-min, QIN Jun, LIAO Guang-xuan, TAN Jia-lei
2009, 39(7): 743-747.
Water mist flux is one of the key factors in flame extinguishment, so total flux was usually discussed in former research works. In order to distinguish the portion of water mist that has a direct influence on the flame or fuel, effective flux was defined based on the current conception of water mist flux. Collecting tubes and the APV (adaptive phase/ Doppler velocimeter) system are two ways currently employed to measure water mist flux. In order to measure the unstable water mist flux and improve the tube-collection method, a water mist generating system and an electronic balance were set up to validate the means of using electronic balance to measure the flux. It was proved that electronic balance can measure flux density effectively and in real-time. Meanwhile, fluxes of different heights have a good correspondence with the results of theoretic calculation. Ununiformity of the water mist field is the reason for the slight difference in results between the experiments and calculation. Some expressions were presented to calculate the dimensional distribution of effective flux density. A lot of fire suppressing experiments can be omitted using the calculation.
Characteristic parameter analysis of boilover fires
TAN Jia-lei, ZONG Ruo-wen, LIAO Guang-xuan, LIU Yi-min, ZHI You-ran
2009, 39(7): 748-754.
Boilover fires in large-scale oil storage tanks can lead to significant losses, and the damage degree of boilover fires is closely related to combustion characteristic parameters. A series of small-scale boilover experiments were carried out, and the variety regulation of parameters including burning velocity (linear burning rate and mass burning rate), heat release rate, flame temperature, radiation and flame height in the combustions of mixed crude oil and mixed oil(kerosene and lubrication oil) during and before boilover were investigated. The experimental results show that these parameters of boilover mutate, so that the values of burning velocity, heat release rate and radiation during boilover can be several times and even dozens of times of those mean values. Based on the qualitative and quantitative analysis, the reason for the mutation was discussed. which can provide a theoretical basis for controlling the loss of boilover during full-scale oil tank fires.
Experimental study on smoke transportation from a narrow-long hallway to the remote room through doors of different sizes
FANG Ting-yong, MAO Jun, LU Ping
2009, 39(7): 755-762.
The reduced scale experimental apparatus was applied to study smoke transportation mechanism. Based on the series of tests conducted on the reduced scale apparatus, smoke transportation from the narrow-long hallway to the remote room was systematically analyzed. The two ends of the hallway were blocked and the smoke could only be exhausted naturally from the remote room. The experimental results show that the size of the opening between the hallway and the remote room has a great effect on the smoke hazard in the remote room. The smoke concentration at the same height sampling point presents an oscillation tendency at a very low level in case of smaller opening size, while it will rise rapidly in a way of multiplication and oscillation decay with the increment of the opening size. Meanwhile, it was found that the smoke concentration at the sampling point in the remote room is higher than in a room close to the fire-origin room in a given period.
Study of flame height of aviation fuel pool fires
ZHUANG Lei, LU Shou-xiang, SUN Zhi-you, WANG Jin-hui, KANG Quan-sheng
2009, 39(7): 763-768.
Aviation fuel pool fire experiments with and without cross wind were carried out in the Wind Tunnel of the State Key Laboratory of Fire Science. Image processing technology based on MATLAB program was built to analyze the flame height of aviation fuel with and without cross wind. In these experiments, the diameters of circular pools are 015, 020, 030 and 060 m and the cross wind speed ranges from quiescence to 35 m/s. The dimensionless number—Richardson number (Ri) was used to analyze the effect of cross wind on pool fires. The result shows that there is a critical value of Ri-1. When Ri-1 increases within the critical value, dimensionless flame height linearity decreases with ln Ri-1. When Ri-1 exceeds this value, the flame configuration remains steady. The critical value of Ri-1increases with pool diameter, however, the steady dimensionless flame height decreases with pool diameter. The relation between flame height without cross wind and pool diameter and burning rate was achieved by theoretical analysis, which shows that the dimensionless flame height Hf/D linearly changes with the Fc number to the power 2/3, and the values of some parameters were obtained by experiment data. Semi-empirical models were also developed to predict the flame height under windy conditions.
Intelligent fire detection based on unsupervised learning clustering algorithm of Dignet
LI Quan-wei, WAN Tian-bin, QIN Jun, LIAO Guang-xuan
2009, 39(7): 769-776.
An algorithm for intelligent fire detection was proposed, which is based on the Dignet ANN and fuzzy algorithm. The idea and implementation of the detection algorithm were introduced in detail. Method for self-adaptation to environment thresholds and for primary data fusion of multi-type fire detectors were given. The algorithm was successfully tested with European standard experimental fire in laboratory.
Experimental study on restraining flashover by ultra-fine water mist in confined space
CHEN Lv-yi, ZONG Ruo-wen, LI Song-yang, WEI Tao, LIAO Guang-xuan
2009, 39(7): 777-782.
Restraining flashover would reduce fire loss effectively. After building a small scale compartment with ultra-fine water mist restraining confined space flashover, the restraining efficiency and influencing factors were investigated. It was found that the restraining effect relies on mist flux, discharging moment and position. With sufficient mist, early discharging showed better effect compared with discharging later, while discharging from the bottom worked better than from side faces. When insufficient mist flux, the combustion enhancing effect would accelerate and intensify flashover.