28 November 2012, Volume 30 Issue 34

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  • LI Yiwen;ZHONG Gansheng;LIU Haiyan;WANG Xi;OU Lina
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    To compare the acute toxicity of the decocted water solution of Sargassum, Radix Glycyrrhizae, the prepared Radix Glycyrrhizae, the Sargassum with Radix Glycyrrhizae, the Sargassum with the prepared Radix Glycyrrhizae, the Haizao Yuhu decoction (Radix Glycyrrhizae) and the Haizao Yuhu decoction(the prepared Radix Glycyrrhizae) in mice, the water extraction components of different groups were prepared, and comparisons were made in accordance with the classical acutetoxicity test methods. The LD50 of the Sargassum water extraction is 35.67g·kg-1·d-1, the water extraction of the Sargassum with the prepared Radix Glycyrrhizae is 44.29g·kg-1·d-1and the water extraction of the Sargassum with the Radix Glycyrrhizae is 50.98g·kg-1·d-1, which are equal to, respectively, 145.2 times, 182.6 times and 211.5 times of 70kg adult's daily dried medicinal herb intake. In the experiment of LD50(n), the death rate of the prepared Radix Glycyrrhizae reaches 50 % by the end of consecutive 8 days, and its LD50(8) is 70.69g·kg-1·d-1.The LD50(19) of the Radix Glycyrrhizae is 82.98g·kg-1·d-1; the LD50(7) of the Haizao Yuhu decoction (Radix Glycyrrhizae) is 79.24g·kg-1·d-1; the LD50(6) of the Haizao Yuhu decoction (the prepared Radix Glycyrrhizae) is 77.49g·kg-1·d-1. The acute toxicity of different groups in mice is: Sargassum > Sargassum with the prepared Radix Glycyrrhizae > Sargassum with Radix Glycyrrhizae > prepared Radix Glycyrrhizae > Haizao Yuhu decoction (the prepared Radix Glycyrrhizae) > Haizao Yuhu decoction (Radix Glycyrrhizae) > Radix Glycyrrhizae. However the toxic substances, the toxicity characteristics, and the toxicity mechanism are not yet entirely clear, and they should be further studied.
  • SONG Liya;QIAO Zhixin;LI Weijing;HE Min;ZHAO Hua;YU Qun
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    Coenzyme Q10 (CoQ10 ) is an endogenous enzyme cofactor that may be found in every cell in the human body and an important natural antioxidant widely used in many fields, such as medicine, food and cosmetics. The protoplast fusion is an important process in the genome shuffling. In order to improve the efficiency of the genome shuffling and the CoQ10 production, this paper studies the conditions of the protoplast preparation and the regeneration of CoQ10 to produce the strain Rhodobacter sphaeroides. The parameters of the proper protoplast formation and the regeneration were determined through the growth curve and the orthogonal experiment: the lysozyme concentration is 1mg/ml, the enzymatic temperature is 37℃; the enzymatic time is 1h and the sucrose concentration is 10%, and under these conditions, the protoplast formation rate is 96.1% and the protoplast regeneration rate reaches 28.8%. Therefore, the optimized conditions of the protoplast preparation and the regeneration for the genome shuffling of Rhodobacter sphaeroides are obtained.
  • LI Zhiyong;PEI Xuan
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    Plaque rupture is a major cause of heart attack. Mechanical factors including blood pressure and shear stress have been found to be related to the rupture risk. The blood vessel is naturally under a periodical and low-level pressure stress state, therefore, the plaque rupture can be treated as a fatigue problem. By simplifying the blood vessel as a cylinder, the crack propagation and the fatigue rupture are investigated. The theoretical solution for an edge crack in a classical cylinder is used to calculate the Stress Intensity Factor (SIF) with the Paris Law being utilized to determine the crack growth rate. The fatigue crack growth is numerically simulated. The various factors that may influence the fatigue life are studied. The results show that when the ratio of the external radius to the internal radius is fixed, the effect of the internal radius on the fatigue crack growth can be neglected; the thrombus with an increase of the wall thickness will reduce the stress concentration, this single factor may have a positive effect to the vascular life from the point view of fatigue; the blood pressure has a great effect on the fatigue life, in an exponential manner.
  • LI Dawei;CHEN Yunxiang;XU Haojun;ZHANG Rong
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    The system safety analysis is widely used in the safety design of an aircraft. For lack of checks for dynamic characteristics of the whole system, the distribution of some reliability indexes may not be reasonable. A comprehensive verification of system dynamic characteristics can be realized through the safety-oriented risk assessment. This paper proposes a new method of distributing the reliability index for FTA (Fault Tree Analysis), based on the cut sets and the importance measure. With the safety design of the FBW (Fly-By-Wire) system for an aircraft's rolling channel as an example, the fallibility index of the top event is distributed. Then the distributed reliability indexes are modified, combined with the flight risk assessed by the Extreme Value Theory (EVT), which plays an important role in the system safety analysis.
  • YIN Dandan;LI Yiqiang;ZHAO Dongfeng;CHENG Guodong;YIN Shuzheng
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    Heavy oil suffers poor fluidity and high viscidity, which poses the main challenge in its exploitation. The reduction of its viscosity is a key to solve this problem. A chemical thermal and catalysis system which is suitable for the heavy oil reservoir is developed. Based on the orthogonal experiment of NaNO2/NH4Cl, the order and the contribution rate of every experiment factor on the target index are determined by means of the range analysis and ANOVA analysis, respectively. By testing the oil before and after the reaction by three catalytic systems, a suitable type of catalytic systems is selected, and the oil after the reaction by the selected catalytic system is analyzed by the gas chromatography. It is found that the influences of different factors on the temperature peak are in the following order: the concentration > the value > the initial reaction temperature. The NaNO2/NH4Cl sample with concentration of 4mol/L can raise the sample temperature by 150℃ at the initial reaction temperature of 60℃; and the Oleic acid nickel is an effective heavy oil viscosity reducer, with a viscosity reduction rate of 80.3%, a significant decrease of the contents of asphaltenes and pectin and an increase of the contents of asphaltenes and saturated hydrocarbon. The laboratory physical simulations show that the smaller the size of the slug, the better is the result. When the size of the slug is 0.1 PV, the oil displacement efficiency can increase 15.6%.
  • ZHANG Guangyin;YANG Shunhui;DOU Ninghui;ZHAO Xiangyang;XIA Bairu
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    The B block in Saudi Arabia is a High Temperature and High Pressure (HTHP) low permeability condensate gas reservoir. The early exploration wells show good behavior,but with not very high production rate. Indoor experiments show that the oil lock and the water lock are the main cause of the reservoir damage. In order to deal with this problem during the drilling operation, the underbalance drilling is adopted. In the design of the negative pressure value in the process, the well control safety, the borehole stability, the oil lock damage, the water lock damage and other factors are taken a full account with respect to their influences on the bottom negative pressure value selection under 2_-10MPa while drilling. In the calculation of the hydraulic parameters, the influence of the temperature and the pressure on the drilling fluid density and viscosity is considered, the industry approved Drillbench software is used to calculate the sensitivity of the drilling fluid density, and finally to determine the drilling fluid density, which is in the range of 1.69-1.76g/cm3. The main equipment includes the rotating blowout preventer, the DDV, the automatic choke manifold, the four-phase separator, the data transmission and processing equipment, the ignition line, and the automatic ignition system. With the setting up of DDV, it is not necessary to shut down the well in the process. In the M-0001 well Sarah group, the real drilling process shows that the fluid density is in the range of 1.69-1.71g/cm3, the bottom hole negative pressure value in the range of 2.08-3.12MPa. According to the M-0001 well test data, the main reservoir skin factor S=3.44, indicating that MTLH-0001 well drilling fluid has a good effect on the gas reservoirs, and the drilling process will not cause the formation pollution.
  • QIN Liming;LI Yongjie;WU Haiyan;ZHANG Yuanchun;LI Sanguo;XIE Guanbao
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    In Yuanba area of northwestern Sichuan Basin, due to complex geological conditions, many complicated downhole accidents occur, such as the well leakage, the borehole collapse and the overflow, which would affect the drilling schedules. Using the GMI well stability software, based on the drilling data, the well logging and the geological information in Well Yuanba11, the mechanical parameters were calculated. Combined with the experiment data, the Young's modulus and Poisson's ratio were converted from dynamic values to static ones. In addition, the minimum and the maximum horizontal stresses were constrained and computed by the fracture information and the wellbore breakout method. Based on above results, the three pressure section, the well stability analysis and the mud scope were investigated, to provide a basis for the drilling design. The results indicate that in Jianmenguan Formation of terrestrial layer, the strata is characterized by fractures and well water permeability, where the fluid would easily be lost. Then in the air drilling section, due to the high and variable collapse pressure, the air drilling is not suitable. After the routine drilling replaces the air drilling, the mud density is lower and near to the pore pressure and the collapse pressure, which would lead to unstable borehole. So, many complicated downhole accidents would occur. While drilling in the depth of 4000m, the mud density is increased so that the complicated situations are mitigated. But in Xujiahe Formation, owing to the low mud density, the pore pressure is so high that the overflow would occur. In the marine section, the mud weight is higher, and actually, the formation pressure is lower. Therefore, the plastic flow of the salt layer would occur and sometimes the stickings may occur, which are distributed in Jialijiang Formation and Changxin Formation.
  • CHEN Xuehua;WAN Changtao;ZHOU Jianwei
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    In order to determine a reasonable coal pillar size suitable for large mining depth gateways, numerical simulations are carried out for the coal pilar of different width. Analysis and comparison are made for the stress distribution of the surrounding rock of roadways, and for the deformation and the plastic failure zones to study the stability of the coal pillar. The results show that the coal pillar internal stress peak distribution is an important factor for determining the reasonable width of the narrow coal pillar along the gob-side entry driving direction, the retained size of the pillar should be determined in a way to avoid a too high stress peak value. When the width of the coal pillar is 6-8 m, the stress peak value under the pillar is not large, the displacements of the roof, the floor and two sides are small. Therefore, the pillar is relatively stable, the maintenance of the gateway becomes easy and the recovering rate is enhanced. At the same time , the coal mine production safety is easy to maintain. The application of this method offers a way for determining the reasonable size of the narrow coal pillar along the gob-side entry driving direction.
  • ZHANG Yuping;LI Chuanxi;ZHANG Lei;LIU Haikuan
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    According to the basic principle of heat conduction and FEM, mass concrete FEM model of Lishui Bridge tower foundation is established by using software MIDAS. Temperature controlling scheme is determined based on the calculation results. Temperature of Lishui Bridge tower foundation is monitored in order to provide evidence for temperature controlling measures including water cooling, heat preservation and moisture retention, etc. Information construction for mass concrete temperature control is implanted. Low thermal cement should be used in mix design of concrete. Adding a certain amount of fly ash into concrete is helpful to control temperature of mass concrete. Cooling water should run through cooling pipe after mass concrete poured, and stop when cooling rate is close to or even greater than 2.0℃/d. If temperature of mass concrete is going up after stopping cooling water, cooling water should run through again. Heat preservation should be done when the inner-surface temperature difference is close to or even greater than 25℃. The temperature controlling scheme is repeated until temperature of mass concrete is stable. Analysis results are introduced. There have been not temperature crack on the surface of tower foundation after mass concrete was poured. Therefore expected target is realized. Engineering practice indicates temperature controlling method and technological process that are introduced in the article are reasonable and effective, and can be used as references for mass concrete construction of bridge tower foundation.
  • REN Liang;JIANG Linzhi;GUO Chengming;YIN Chunyan;YU Feiyang
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    The high uncertainty in the thickness measurement of post irradiation sheet was analyzed, and based on the analysis, a large number of measurement tests were taken, a series of improvements were proposed. The manipulator driving measurement was replaced with the action-oriented measurement, which has effectively solved the problems concerning the stick side determination, the standard block fixing and the control of the head contact forces. The measurement uncertainty was reduced by one order of magnitude. The radiation dose, the labor tension and the time were likewise reduced with very significant economic and social benefits.
  • ZHAI Zengxiu;LIU Yingchun;ZOU Kehua;WANG Gen;YAN Fengyue;LIU Yinghui;WANG Jianzhuang;
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    To study the pollution characteristics of halohydrocarbons in Tianjin urban ambient air, 26 sampling points were selected to monitor the contents of the halohydrocarbon in summer with the Jixian Kowloon peak scenic area as the control point. The Agilent 7890A/5975C GS-MC spectrometer was used for the quantitative detection of 8 kinds of halohydrocarbon, with the detection rate for 5 kinds of halohydrocarbon greater than 50%, that is, dichloromethane, chlorobenzene, dichlorodifluoromethane, trichlorofluoromethane and chloromethane. This paper focuses on these five kinds of halogenated hydrocarbons and it is shown that the average concentrations of the five halohydrocarbons from high to low are: 6.75μg/m3(chlorometham), 5.43μg/m3(dichlorodifluomethane), 4.09μg/m3(dichloromethane), 2.95μg/m3(trichlorofluoromethane) and 0.46μg/m3(chlorobenzene). Among the six city areas and different function areas, the halohydrocarbon concentrations are generally high in the Nankai District and lower in the Hexi District. The methyl chloride and benzene concentrations in the functional areas are higher than in the control point, and the trichlorofluoromethanes concentration in the business area is significantly higher than in other functional areas.
  • Reviews
  • QIN Yong;YUAN Liang;CHENG Yuanping
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    The strategic benefits of the coal bed methane (CBM) industry involve the overall contribution of the CBM industry development to the economy and thr community in general, and the factors influencing the benefits are discussed in the lights of the national energy supply-demand tendency and the conditions for the CBM industry development. Macroeconomic factors affecting the development and its strategic benefits of CBM industry in China include the economic situation, the coal production, the clean energy production and the environmental protection The future economic situation is uncertain, the future energy demand is in a continued growth, and the development of new energy and low-carbon technologies will stimulate the substantial growth of the natural gas (including CBM) production and consumption. As far as the micro-level is concerned, the CBM production is a key for the assessment of the industry strategic benefits, which is affected by the CBM resources and its proven degree, the CBM-extracting method and the technology, the capital investment and so on. The CBM resources in China are very rich but the proven resources are at a low level and in complex geological conditions, indicating a huge potential of the strategic benefit release and the high requirements for the innovation of CBM extracting technologies. The level of the technological development determines the degree of the strategic benefit realization of the CBM industry, the technological research and development should focus on the improvements of both the CBM production of the surface wells and the mine drainage in order to develop CBM-extracting technologies applicable to various types of geological conditions. The CBM development requires a high upfront investment and involves a high investment risk, and a long payback period, which requires a diversified investment and financing platform supported by the national policies.
  • LI Huiyan;FANG Yuehua;XIAO Kui;HE Gang;GUO Chunyun;DONG Chaofang;LI Xiaogang
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    In the western dry and hot atmosphere environment, the corrosion and abrasion behavior of coatings has a direct bearing on the service life of all kinds of machinery, vehicles and others. The western desert environment is characterized by the large temperature difference between day and night, the high UV strength, and the large amount of dust, which poses a high requirement with respect to the corrosion resistance of coatings. This paper reviews the research progress related with the corrosion and abrasion of coatings in bad natural environments of high temperature difference, high irradiation intensity and large quantities of dust. The following conclusions are drawn. In the high temperature difference environment, the failure is mainly due to the changes in the expansion coefficient and the structural changes of the coatings. In the high irradiation intensity environment, the failure is mainly due to the coating materials degradation because of their molecule absorption energy. In the dust environment, the failure is mainly due to the coating materials deformation under the actions of sand cutting and compression. This review may help the further research of the service behavior of coatings in dry and hot atmosphere environment.