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   Science & Technology Review
2013, Vol.31, No. 5-6
28 February 2013

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卷首语

Science & Technology Review. 2013, 31 (5-6): 3-3. ;  doi:
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Abstract ( 129 )
科技风云

Science & Technology Review. 2013, 31 (5-6): 7-7. ;  doi:
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Abstract ( 138 )
特别栏目

Science & Technology Review. 2013, 31 (5-6): 8-8. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 8-8. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 10-10. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 11-11. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 12-12. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 13-13. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 14-14. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 32-32. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 113-113. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 114-114. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 118-120. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 121-121. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 122-124. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 126-126. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 127-127. ;  doi:
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Science & Technology Review. 2013, 31 (5-6): 128-128. ;  doi:
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科技事件

Science & Technology Review. 2013, 31 (5-6): 9-9. ;  doi:
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Exclusive

Science & Technology Review. 2013, 31 (5-6): 15-20. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.001
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Abstract ( 523 )
Spescial Issues

Preparation of Positive Material in Lead-acid Battery by the Chemical Conversion of Lead Sulfate

GAO Pengran;LIU Yi;BU Xianfu;LEI Lixu
Science & Technology Review. 2013, 31 (5-6): 21-24. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.002
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Abstract ( 422 )
Sulfation is one of important reasons for the failure of lead-acid batteries, therefore, lead sulfate desulfurization and calcination in order to prepare lead oxide with good electrochemical activity has important significance. A method to transform lead sulfate into lead oxide with the reaction of ammonium carbonate and calcination is introduced. At the first, lead carbonate is obtained in a synthesized solution, after filtration, it is calcined at the temperature of 350 ℃, therefore lead oxide with good electrochemical activity could be produced. The prepared sample and ball-milled sample are analyzed by X-Ray powder diffraction, scanning electron microscopy, respectively. The charge and discharge performance test are carried out and result is obtained that the prepared sample has a higher capacity than factory sample. Finally, the calcination temperature for preparation of samples is compared with different temperatures in term of electrical properties, and the best calcination temperature to prepare samples is obtained. In optimum conditions, uniformed and homogeneous structured lead oxide powder with the particle size of 200~300 nm is prepared. The synthesized lead oxide, as positive of lead-acid batteries, shows a good discharge capacity; the capacity value is 120mAh/g at the discharge rate of 0.5C. Finally, the sample after discharge is analyzed by X-Ray powder diffraction.

Electrochemical Behaviors of the 316L Stainless Steel Welding Seam Corrosion

LÜHongwei;DONG Shigang;WANG Jingjing;LI Ning;LIN Changjian
Science & Technology Review. 2013, 31 (5-6): 25-28. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.003
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Abstract ( 293 )
The effect of two different techniques, including Argon tungsten arc welding (TIG) and CO2 shielded arc welding, on the welding seam corrosion behavior of the 316L stainless steel, and whether or not the concentration of chloride ions affect the welding seam corrosion of the welding samples are explored. The samples are studied by the traditional electrochemical techniques, such as potentiodynamic polarization curve, electrochemical impedance spectroscopy, and scanning microelectrode technique which is self-assembly made by authors. In conclusion, it is indicates that the corrosion resistance of welding seam zone is lower than that of base materials in any situation. In the NaCl and FeCl3 solutions with different concentration, the anti-corrosion performance of the Argon tungsten arc welding samples are better than that of CO2 shielded arc welding samples. The conclusion is all verified by the three different techniques. Besides, it is also concluded that the corrosion resistant of the both welding samples and base materials are decreased with the increase of the concentration of chloride ions.

Preparation of 0.55PNN-0.45PZT Piezoelectric Ceramics by and Doped with Fe2O3 Using Microwave Sintering and Its Properties

DU Jianzhou;QIU Jinhao;ZHU Kongjun;JI Hongli
Science & Technology Review. 2013, 31 (5-6): 29-32. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.004
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Abstract ( 261 )
Microwave sintering is a novel and high efficiency sintering technology for ceramics, which exhibits many significant advantages, such as high rapid heating rate, energy saving and shorter sintering time, microstructures improvement, and lower sintering temperature. The 0.55Pb(Ni1/3Nb2/3)O3-0.45Pb(Zr0.3Ti0.7)O3(0.55PNN-0.45PZT) piezoelectric ceramics by doping with Fe2O3 were prepared using the microwave sintering process at 1,200℃ for 2h. The effect of Fe2O3 doping on microstructure, dielectric and piezoelectric properties were investigated by using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), impedance analyser, and ferroelectric tester in detail. The XRD results indicate that all samples possess typical pervoskite phase. In addition, both the piezoelectric and dielectric constants increases firstly and then decreases with increasing x. The optimum electrical properties of d33=520pC/N, kp=0.51, εr=4768, and tanδ=0.026 are obtained for the 0.55PNN-0.45PZT ceramics by doping with 0.8% Fe2O3.

Variation pattern of Magnesium Particles in Sintering Process and Its Influence on the Manufacture of Aluminum Foam

LIN Hao;LUO Hongjie;SUN Wei;YAO Guangchun
Science & Technology Review. 2013, 31 (5-6): 33-36. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.005
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Abstract ( 327 )
The method for increasing the dense of foamable precursors in the process of manufacturing the aluminum foam by powder metallurgy route has been studied. The factors which have influence on the dense of foamable precursors in the process of preparation and the densification process have been discussed. The influence of sintering temperature and sintering time on the structure in the foamable precursors and the densification has also been discussed. The main discussion is focused on the influence of the sintering on the variations of magnesium particles and the quality of the aluminum foam manufactured by powder metallurgy. As for the matrix material which particles size is between 75~150μm, the foamable precursor which is sintered at 450℃ after cold compression would increase its density and the continuity of the matrix. The sintering time should not be less than two hours,therefore the size of the magnesium particle will be twice or even three times larger than that for the one that is not sintered. The results reveal that high quality aluminum foams could be obtained by uniaxial cold compaction under the pressure 400MPa with sintering at 450℃ for two hours. In this way, the quality of the aluminum foam could be better than the one without sintering.

Effects of Keeping Warm Time on the Properties of In-situ Synthesis Si3N4 Bonded MgO-C Refractory

PENG Nai;DENG Chengji;ZHU Hongxi;YUAN Wenjie;XU Bin
Science & Technology Review. 2013, 31 (5-6): 37-39. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.006
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Abstract ( 249 )
MgO-C refractory was prepared by taking high quality fused magnesia, silicon powder, and flake graphite as raw materials, liquid calcium lignosulfonate with the concentration of 1.25g/mL was used as the binder. Then the samples were sintered under N2 atmosphere via two-stage sintered process that a low-temperature stage is with 1350℃ for 2h and a high-temperature stage is with 1450℃ for 2h, 3h, and 4h, respectively. The effects of keeping warm time on phase compositions, microstructure, and conventional physical properties of MgO-C refractory are investigated. The phase composition of fired samples is analyzed by X-Ray diffraction. The microstructure is analyzed by scanning electron microscope. The conventional physical property is characterized by apparent porosity, bulk density, and compression. The results show that there are no evidently differences on the phase compositions and the size of SiC and α-Si3N4 whisker formed through the in-situ formation with the increase of keeping warm time from 2h to 3h. With the increase of keeping warm time to 4h, the silicon phase disappeared and the sizes of SiC and α-Si3N4 whisker have obviously increased. For the conventional physical performances, with the increase of keeping warm time from 2h to 4h, the formation of CO(g) and SiO(g) is increasing, which lead to a increase of apparent porosity and a decrease of bulk density and compression strength.

Influential Factors in the Solid Carbothermic Reduction of Chromite

ZHAO Qing;LIU Chengjun;JIANG Maofa;QI Jie;ZHANG Qingsong
Science & Technology Review. 2013, 31 (5-6): 40-43. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.007
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Abstract ( 199 )
Chromite is one kind of national strategic resources in the all countries of the world. It is widely used in various fields, such as metallurgy, refractory, and chemical industry, etc. However the large amount of chromite power that is generated by the process of mining is difficult to effectively utilization. In order to solve the problem, researchers put forward the technology of solid carbothermic reduction of chromite. By directly placing the mixed material that contains chromite fines and solid carbon into the high temperature furnace for reduction reaction. In this process, iron oxides are able to be selectively reduced from chromite; therefore higher rate of chromic oxide-ferrous oxide to chromite fines could be obtained. The mechanism and influence factors for the solid carbothermic reduction of chromite are concluded. The influential factors include reduction temperature, reduction time, types of reductant, gas flow rate, size of particle and pellet, and additive species. This research would offer guidance for efficient utilization of low grade chromite fines. The research suggests that the influence of majority factors on the solid carbothemic reduction of chromite is nonlinear, and optimum values are always able to be obtained. For this reason, choosing optimum process conditions is significant for improving product quality and reducing product costs.

Dynamic Recrystallization Behavior of Ti-7333 Alloy in the β Hot Process

FAN Jiangkun;KOU Hongchao;TANG Bin;CHANG Hui;LI Jinshan
Science & Technology Review. 2013, 31 (5-6): 44-48. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.008
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Abstract ( 267 )
The effects of processing parameters on deformation microstructure evolution and dynamic recrystallization behavior of a new near β titanium alloy were investigated by using the Gleeble-3800 thermal and mechanical simulator in the temperature range of 870-970℃ and strain rate range of 10-3-10s-1. The results indicate that Ti-7333 alloy exhibits a typical DRX behavior at higher deformation temperature with lower strain rates. The recrystallization grain size and recrystallization volume fraction are also increase with the increase of deformation temperature and the decrease of strain rates. And strain rate affects the recrystallization grain size significantly. The grains are seriously deformed and elongated with higher strain rate (>0.1s-1) and lower temperature (<870℃), however dynamic recrystallization will hardly occur. The recrystallization grain size is determined by Zener-Hollomon parameter Z, and an exponential function relation is held between Dr and Z. The model of dynamic recrystallization grain size is established by regression analysis method, that is, lnDr=8.50949-0.31411lnZ. It is able to accurately predict the grain size of dynamic recrystallization under a certain deformation condition and lay a scientific foundation for microstructure controlling during hot deformation. Inappropriate thermal deformation process could cause coarse or non-uniform materials microstructure, thus deteriorating the performance. Thereby, the best hot deformation parameters must be selected from the perspective of microstructure uniformity and grain refinement.

Thermal Baking Process Analysis of Foaming Gypsum Mold

FAN Zhenzhong;XIONG Yancai;WANG Shengqiang;ZHANG Kun;YANG Shoujie
Science & Technology Review. 2013, 31 (5-6): 49-53. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.009
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Abstract ( 201 )
By taking thermal baking process of foaming gypsum mold as a research object, the temperature variation, dimensional changing, and organizational transformation of the foaming gypsum mold in the overall thermal baking process were studied using K-type thermocouple, multi-channel temperature logger, vernier caliper, and Scanning Electron Microscopy (SEM), respectively. The results indicate that the temperatures of the internal points lag behind the process temperature entirely; the temperature difference curve of internal point gradually rises with the increase of heating temperature and the time for keeping warm. By the slough off of the internal free crystal water and the corresponding crystal transformation of gypsum, one-dimensional size in the length direction of mold first continuously declines and then increases slightly, the shape of gypsum grain changes from acicular shape to bulky cylindrical or lamellar appearance, subsequently transformating to needle morphology shape.

Lipase Immobilization Through Ion Exchange Resins

ZHANG Ruzhuang;ZHOU Yanbo;ZHU Mingying;LU Jun;
Science & Technology Review. 2013, 31 (5-6): 54-57. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.010
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Abstract ( 357 )
L4 lipase was immobilized on four kinds of resins by adsorption, involving ion exchange resins and macroporous resins. The influences of carriers and lipase concentrations on the adsorption amounts and activities of immobilized lipases were investigated. Then the L4 Lipase was immobilized on ion exchange resin (DK110) by a method so called adsorption and cross-linking, in which glutaraldehyde is used as the cross-linking agent. The influences of glutaraldehyde concentration and cross-linking methods on the lipase immobilization were also investigated. The results show that macroporous ion exchange resin (DK110) is proved to be the most suitable immobilization supporter; the activity of the immobilized lipase is 292U/g when the lipase concentration is controlled at 50mg/mL. Lipase concentrations and cross-linking methods have a great impact on the immobilization of lipase, either strengthen or weaken. Under the same conditions, lipases immobilized by adsorption and cross-linking treatment exhibit higher activities compared with the lipases immobilized by simple adsorption. Furthermore, lipases immobilized by JL1 exhibit the highest activities, which are 340U/g, and lipases immobilized by JL2 are very much stable in repeated usage, they remain 53% of the initial activity after six cycles. This research might lay the foundation for the further study on bio-diesel based on the immobilized lipases.

The Growth Characteristics of Human Retinal Pigment Epithelium Cells and the Influence of Visual Light on the Characteristics

SUN Min;LÜXiaoling
Science & Technology Review. 2013, 31 (5-6): 58-62. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.011
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Abstract ( 226 )
The research object is to study the growth characteristics of human Retinal Pigment Epithelium (hRPE) cells, and to investigate the damage to them which is induced by visual light. Inverted phase contrast microscope and transmission electron microscope were used to observe the morphology and microstructures of hRPE cells, respectively. Growth curve was depicted by both cells counting and MTT methods. Exposure time, FBS is free or not, replacing medium or not, and incubation time post irradiation were selected as the factors to estimate the photo-damage in hRPE cells. The results show that the hRPE cells incubated in vitro are polygonal and polarized, normal organelle and vigorous growth are also observed. The illumination for two hours with an intensity of (8,423±359)lx had already caused photo-damage. Exposed for five hours with 10% FBS in medium which is not replaced post irradiation and incubated for 24h subsequently, the damage rate of hPRE cells goes up to 58%. In conclusion, the hRPE cells cultured in vitro show normal morphology and regular growth rhythm. Visual light could cause damage to hRPE cells and the damage degree is correlated with the illumination duration and post-incubating time. Therefore the illumination directly from the sun should be avoided and reducing the illumination duration in order to protect human eyes.

Adsorption and Desorption of Aqueous Acid Fuchsine on Ferrihydrite

WU Yongjuan;;YAN Junying;ZHANG Qian;CHEN Rufen;WEI Yu;WU Dong
Science & Technology Review. 2013, 31 (5-6): 63-66. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.012
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Abstract ( 231 )
Acid Fuchsine (AF) was selected as a model anionic dye to examine the adsorption-desorption behavior of ferrihydrite to acid fuchsine by using batch equilibration technique. The useful data is provided for the industrial treatment of acid fuchsine and the similar pollutants. The effect of solution pH and temperature on the adsorption of AF onto FH was investigated in detail. The results indicate that ferrihydrite has an optimum condition for the removal of AF at pH 4.0. The maximum adsorption capacity reaches 392.2mg·g-1 at 297K. Adsorption isotherms of AF at different temperatures are conformed to the Langmuir equation, indicating one monomolecular layer of the coverage on FH surface. The data of Gibbs free energy, enthalpy, and entropy of the adsorption show that the adsorption of AF onto FH is an irreversible, spontaneous, exothermic and chemical process. The AF desorption from FH is also investigated. The isotherms of AF desorption are also conformed to Langmuir equation. The constant values of desorption intensity are much lower than that of adsorption at 297K and 323K with three different concentrations, indicating that AF desorption from FH shows significant hysteretic effect. The hysteretic coefficient decreases with the increase of AF initial adsorbed concentration or temperature. The desorption rates of AF from FH at different initial concentrations or temperatures are below 9%, therefore the adsorption of AF onto FH has the good stability. On the whole, FH is a highly efficient adsorbent for the removal of AF from contaminated water.
Articles

Design Criteria for Variable Range of Gravity Center for a Large Subsonic Aircraft with Relaxed Static Stability

GENG Jianzhong;WU Huzi;DUAN Zhuoyi
Science & Technology Review. 2013, 31 (5-6): 67-71. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.013
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Abstract ( 285 )
The controls of the traditional natural stable subsonic large aircraft and the modern subsonic large aircraft with relaxed static stability are analyzed. The design criteria for variable range of the allowable center of gravity are proposed based on demands for the subsonic large aircraft with relaxed static stability and various influencing factors. The relation formulas under different influencing factors between the relative horizontal tail area and the center of gravity are obtained. The curve of the center of gravity against the relative horizontal tail area is found to be different from the traditional "scissors figure". If the relative horizontal tail area is given, the scope of the center of gravity can be easily determined. To illustrate the feasibility and the reliability of the proposed design standards, a verification calculation is carried out based on a special plane. Through the analysis of the calculation results, the main factors that influence the design of the scope of the center of gravity are obtain, including the initial rotation and the taxi stability. The optimum performance of the center of gravity can be fully used in adjusting the landing gear position and the design cruising speed.

Band Structures of Phononic Crystal Beam on Elastic Foundations

ZHANG Ziming;CHEN Qiyong;NI Zhiqiang;HAN Lin;ZHANG Yan
Science & Technology Review. 2013, 31 (5-6): 72-75. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.014
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Abstract ( 214 )
This paper studies the vibration characteristics of the phononic crystal beam on elastic foundations, based on the Euler beam theory and the Winkler foundation model. The finite element method is used to obtain the band structures of phononic crystal Euler beams. The results reveal the influence of the foundation constraint on the bending vibration band gaps in the phononic crystal Euler beam. The computational results of the band structures of the phononic crystal Euler beam without foundation are compared with those on the elastic foundation. The significantly different band gaps of the model are shown. The influences of different component ratioes of the phononic crystal Euler beam model are also studied, as well as the frequency ranges of the vibration band gaps.

Rock Mechanics Properties of Glutenite Formation and Bit Structure Optimization

ZHU Haiyan;DENG Jingen;ZHU Xiaomei;LI Ben;HUANG Kaiwen;DENG Fucheng;ZHAO Yongli;DU Xiangdong
Science & Technology Review. 2013, 31 (5-6): 76-80. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.015
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Abstract ( 262 )
In order to improve the Rate of Penetration (ROP) of the glutenite formation in the Pearl River Mouth Basin (PRMB) Oilfields, the lithological characters of glutenite formation was identified by the X-Ray diffractometer. Laboratory experiments on core Uniaxial Compressive Strength (UCS), drill ability, and abrasive property were conducted to study their rock mechanics properties. According to the rock mechanics properties and the drilling data of the used PDC bit, the Polycrystalline Diamond Compact (PDC) cutters are optimized in terms of the bit crown, cutters distribution method, and hydraulic structure of the PDC bit. Comparing with the bits used in the adjacent wells, the drilling footage and the ROP of the optimized PDC bit are improve by 131% and 48%, respectively; and the drilling cost per meter is also reduced by 28%. The bit optimization method proposed takes the effects of the rock mechanics parameters, the drilling data of the used PDC bits, and the total property of all the bit parts into consideration and is simple and effective, which might be able to apply to the bit optimization of complex formation in the future.

Design of Point by Point to Obtain the Rock Element and Its Application

WANG Jingci;GUO Haimin;WANG Huawei
Science & Technology Review. 2013, 31 (5-6): 81-86. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.016
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Abstract ( 246 )
The rock components are very important for the logging interpretation of complex lithology reservoir. In order to obtain the ratio of rock matrix components point by point quickly and accurately, a fuzzy clustering method was discussed by taking the Biyang dolostone reservoir as an example. First, logging parameters were processed by principal component analysis and the purpose is to reduce the number of dimensions. Samples were processed by routine standardization, mean processing standardization, and logarithmic transformation standardization. The cumulative variance contribution rates of the first three principal factors are 86.07%, 96.97%, 96.71%, respectively. Then the samples are clustered and the classification number of k-means clustering is discussed. Finally, the lithologic component is point by point and quantitatively obtained by using the idea of fuzzy mathematics and calculating the degree of membership. The results show that the method is effective and suitable for the analysis of a large number of well logging data. It is worth to point out that this method is also effective when the new materials of logging technique are lack of.

Relationship between Asthma Patients with Abnormal Savda and the Gene Polymorphism of IL-13

TUERXUN Kelibiena;SIMAY Mihereguli;AIZEZI Renaguli;WUFUER Dilinuer;UPUR Halmurat
Science & Technology Review. 2013, 31 (5-6): 87-91. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.017
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Abstract ( 296 )
According to the body fluid theory of Uygur Medicine, 76 cases of asthmatic patients were diagnosed. Among them, there were 30 cases of asthmatic patients with abnormal savda and 46 cases of asthmatic patients with normal savda. The gene polymorphism of IL-13 on loci intron3+1923 and loci +2044 of these patients are tested by using PCR-RFLP, the results are compared with that of the 89 normal individuals in order to explore the relationship between asthmatic Xinjiang Uygur patients with abnormal savda and the gene polymorphism of IL-13. There is significant difference of gene polymorphism of IL-13 on loci intron3+1923 in all three groups(P<0.01). The distribution rate of genotype TT and TC in asthmatic patients with abnormal savda is significantly higher than that of the asthmatic patients with normal savda and the normal control group(P<0.01). The distribution rate of genotype TT and TC in asthmatic patients with normal savda is significantly higher than that of the normal control group (P<0.05). The distribution rate of genotype CC in normal control group is significantly higher than that of the asthmatic patients with abnormal savda(P<0.01) and higher than that of the asthmatic patients with abnormal savda (P<0.05). The distribution rate of genotype CC in asthmatic patients with normal savda is significantly higher than that of the asthmatic patients with abnormal savda(P<0.05). There is significant difference in the distribution rate of allele C and T in all three groups(P<0.01). The distribution rate of allele T in asthmatic patients with abnormal savda is significantly higher than that of the normal control group(P<0.01). The distribution rate of allele C in asthmatic patients with abnormal savda is significantly lower than that of the normal control group(P<0.05). There is insignificant difference in the distribution rate of IL-13 on loci +2044 and the distribution rate of its alleles in all three groups(P>0.05). In short, Asthma in Xinjiang Uygur Patients with abnormal savda might be related to the gene polymorphism of IL-13 loci intron3+1923, but is not related to the gene polymorphism of IL-13 on loci+ 2044.

Seasonal Dynamics of Belowground Biomass of Stipa klemenzii Steppe and Its Environmental Influent Factors

YANG Tingting;GAO Yong;WU Xinhong;SHI Hongxiao;LI Peng
Science & Technology Review. 2013, 31 (5-6): 92-97. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.018
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Abstract ( 268 )
The lack of measured data on belowground biomass seriously affects the accurate estimation of grassland belowground carbon pool. By taking stipa klemenzii steppe as the research object, six sample plots were selected, and 2,160 root samples were collected for further experimental analysis via wild plots investigation, the seasonal dynamics of belowground biomass from May to September was analyzed. The results show that (1) the change trend of belowground biomass appears a "N" type, and the peak value appears in late July, and the lowest value appears in late August, the belowground biomass of grassland type of Caragana stenophylla Pojark-Stipa klemenzii+Cleistogenes songorica in each month is higher than that of grassland type of Stipa klemenzii+Cleistogenes songorica. (2) The seasonal dynamics of belowground biomass in different soil layers of Stipa klemenzii steppe is different, belowground biomass in the layer of 0-10cm appears a large fluctuation, which is consistent with the trend of total belowground biomass. Curve below the layer of 10cm is steadily stable. (3) There is no obvious correlation between below-biomass and soil organic carbon content in the soil layer of 0 -60cm. However, in the layer of 0-10cm, the soil organic carbon content is significant positive correlated with belowground biomass from May to July. (4) There is no obvious correlation between belowground biomass and monthly precipitation or monthly average temperature. (5) Belowground biomass in different soil layers has a significant positive relation with soil moisture; total belowground biomass is greatly influenced by soil moisture in the layer of 0-10cm.
Reviews

The Research Progress in the Applications and Modification of Dialysis-membranes

YU Jingang;JIANG Xinyu;JIAO Feipeng;CHEN Xiaoqing;TAO Lijian
Science & Technology Review. 2013, 31 (5-6): 98-105. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.019
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Abstract ( 342 )
Acute or chronic renal failure is a deadly severe disease. There are only two ways to cure these diseases, namely, hemodialysis and kidney transplant. Hemodialysis is the main means for curing patients at present. The key hemodialysis equipments are dialysis-membranes. The demand for dialysis-membranes with high performance is unceasingly rising. The types of dialysis-membranes and their preparation techniques, and the methods and theories for their modification are summarized. The advantages and disadvantages of cellulose, cellulose acetate (CA), chitosan (CS), polysulfone (PS), poly(ether sulfone) (PES), polyacrylonitrile, ethylene-vinyl alcohol copolymer (EVOH), poly (methyl methacrylate) (PMMA), and poly(vinyl alcohol) (PVA) are introduced in detail. With continuously heightened demands for the use of dialysis-membranes, some new ideas for improving the biocompatibility and related physicochemical properties for dialysis-membranes by chemical modification or designing new dialysis-membranes are presented. The results possess some reference value for researching and developing novel dialysis-membranes.

Research Progress in Chemical Sand-fixing Materials in Desertification Combating

TIE Shengnian;JIANG Xiong;WANG Chang'an;
Science & Technology Review. 2013, 31 (5-6): 106-111. ;  doi: 10.3981/j.issn.1000-7857.2013.h1.020
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Abstract ( 293 )
The research progress in desertification combating at home and abroad, involving inorganic chemical sand-fixing materials, organic chemical sand-fixing materials, and organic-inorganic compound sand-fixing materials, are reviewed. The principle of chemical sand fixation is that the fixation forms a consolidated layer with certain structure and strength in the surface of quicksand. It could prevent the wind erosion and keep the underlying moisture. Chemical sand fixation usually includes five aspects, that is, felting effect, surface coverage effect, hydration, gelifaction, and polymerization. The existing problems and the necessity for developing advanced chemical sand-fixing materials are pointed out. The technical support for the development of advanced chemical sand-fixing materials with the features of low cost, high performance, suitable for the growth of vegetation, environmentally friendly, degradation, large-scale executable is provided.
书评

Science & Technology Review. 2013, 31 (5-6): 112-112. ;  doi:
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Abstract ( 222 )
主编心语

Science & Technology Review. 2013, 31 (5-6): 115-115. ;  doi:
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Abstract ( 133 )
科技纵横捭阖

Science & Technology Review. 2013, 31 (5-6): 116-116. ;  doi:
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Abstract ( 155 )
科技职场

Science & Technology Review. 2013, 31 (5-6): 117-117. ;  doi:
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Abstract ( 129 )

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