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   Science & Technology Review
2010, Vol.28, No. 04
28 February 2010

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Deepening Educational Reform and Developing Outstanding Talents

Science & Technology Review. 2010, 28 (04): 1-1. ;  doi:
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Abstract ( 573 )
特别栏目

Science & Technology Review. 2010, 28 (04): 8-8. ;  doi:
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Abstract ( 491 )

Science & Technology Review. 2010, 28 (04): 10-10. ;  doi:
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Abstract ( 505 )

Science & Technology Review. 2010, 28 (04): 12-12. ;  doi:
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Abstract ( 509 )

Science & Technology Review. 2010, 28 (04): 13-13. ;  doi:
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Abstract ( 506 )

Science & Technology Review. 2010, 28 (04): 14-14. ;  doi:
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Abstract ( 509 )

Science & Technology Review. 2010, 28 (04): 133-133. ;  doi:
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Abstract ( 488 )
封面图片说明

Science & Technology Review. 2010, 28 (04): 8-8. ;  doi:
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Abstract ( 491 )
半月科技风云

Science & Technology Review. 2010, 28 (04): 9-9. ;  doi:
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Abstract ( 540 )
科技事件

Science & Technology Review. 2010, 28 (04): 11-11. ;  doi:
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Abstract ( 541 )
Exclusive

A Comparative Study on the Training of Talents of Mathematics in China and in Japan from 1868 (the Meiji Restoration in Japan)

Science & Technology Review. 2010, 28 (04): 15-20. ;  doi:
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Abstract ( 805 )
During the 200 years of the 18th and 19th centuries, Europe produced numerous great mathematicians, while the oriental world remained relatively quiet in mathematics. Before 1868 (the Meiji Restoration in Japan), China fared better than Japan with respect to the achievements in that field, but China was overtook by Japan at the end of the 19th century. This paper presents a comparative study on the training of talents of mathematics in China and in Japan during the period from 1868 to the Second World War, to show the causes why China followed a downward road to become lagged behind Japan and the rest of the world in mathematics. In Japan, the Meiji Restoration required its citizens to learn from Western countries in all fields in an all round way; in China, on the other hand, it was advocated to learn Western science and technology on the basis of the Chinese traditional system. With the latter altitude, one could not seek truth whole-heartedly, which constitutes the most important cause for China to be lagged behind in mathematics and other sciences. Another reason is that in the early stage of learning from the West, Chinese tended to focus on technology and lacked the enthusiasm for mathematics. The importance of the most advanced mathematics was not recognized until the twenties of the 19th century and the frontlines in this field were not touched upon. The rapid development of mathematics in Japan had also something to do with their methods of learning. No great mathematician would be produced without the enthusiasm of researching and taking it as a loft goal. The prospect of mathematics in today's China depends on the training of young mathematicians. The training of graduate students should be traced to the training of middle school students. It is expected that the enthusiasm for mathematics will again be prevailed in Chinese.
Articles

Observation on Pathological Changes in the Liver and Kidney of Nine Cases of Pandas

Science & Technology Review. 2010, 28 (04): 21-27. ;  doi:
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Abstract ( 681 )
The samples of nine cases of panda liver and kidney were collected from the veterinary hospital of Beijing Zoo. The histopathological method was used to observe the pathological lesion of the liver and kidney tissues. The cytochemistry and immunohistochemistric methods were used for detection of the hepatitis virus infection in pandas. The results show that, there are varying degrees of pathological changes in liver and kidney tissues in all samples. The livers see extensive congestion, edema and hemorrhage, and widespread degeneration and atrophy of hepatocytes are observed in some cases. Apart from sporadic necrosis, hepatocytes show multiple-focal necrosis and widespread necrosis. Bile duct proliferation is present in the portal area. The liver interstitium shows inflammatory cell infiltration and fibroplasia. Hemosiderin pigmentation is found in the liver in all cases. Kidney pathological changes consist of extension of the renal glomerulus capsular space, degeneration and necrosis of renal tubular epithelial cells, fibrosis and inflammatory cell infiltration of renal interstitium, and protein cast in the renal tubular. Immunohistochemistry shows that both the positive detectable rates of HBV and HEV are high, however, the extents of the positive reaction are obviously different. Mallory trichromatic staining shows that different levels of proliferation of the fibrous tissue are found in the liver and kidney tissues in the nine cases of pandas. These studies provide evidence that the inflammation reaction prevails in the liver and kidney tissues in the nine cases of pandas and the initiation of the inflammation may be closely related to HBV and HEV.

Laparoscopic Tension-free Repair for the Esophageal Hiatal Hernia

Science & Technology Review. 2010, 28 (04): 28-30. ;  doi:
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Abstract ( 625 )
To investigate the clinical effects of the laparoscopic tension-free repair of the esophageal hiatal hernia using meshes, from August 2006 to April 2009, 40 patients with esophageal hiatal hernia were treated by ultrasonic scalpel under laparoscopy to isolate esophageal hiatal hernia, which was then repaired using meshes. Toupet partial fundop lication was performed. For all patients, the laparoscope tension-free repair was successfully performed (13 of type I, 4 of type II, 15 of type III and 8 of type IV). All patients have the symptoms of heartburn and regurgitation; for some patients the symptoms are accompanied with nausea, vomit and dysphagia. The operation lasts 90min in average (70~170min) with the blood loss between 10~210mL. No case of death. 10 patients were completely recovered after the operation. The mean postoperative hospital stay was 5d(3~30d). The patients were followed up for 3~25 months (12 months in average), no case of recurrence of the hernia, and no complication with regards to the use of meshes. Laparoscopic mesh of tension-free prosthesis is shown to be a secure and minimally invasive operation for esophageal herination, with a very small recurrence rate.

Radioprotection of Vanillin Derivative VND3207 Against Genomic DNA Damage of Human Fibroblastoid Cells Induced by α Particles

Science & Technology Review. 2010, 28 (04): 31-36. ;  doi:
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Abstract ( 734 )
As a high linear energy transfer (LET) radiation, ?琢 particles mainly induce DNA clustered damage with low repair efficiency and serious biological effects. There is still no effective radioprotection agent available against the biological detriments induced by ?琢 particles. The vanillin derivative VND3207 is a novel radioprotection agent with an antioxidant potentiality and protective effects against the genomic DNA damage and apoptosis induced by low LET γ-ray. The present study is designed to determine the radioprotective effect of VND3207 against the genomic DNA damage of human fibroblast HFS cells induced by high LET α particles. The clonogenic survival assay shows that VND3207 can significantly enhance radioresistance of HFS cells to the irradiation of α particles, no matter the cells are treated with VND3207 before or after irradiation. Multiple indicators of DNA damage detection, including single cell gel electrophoresis, immnuo-fluorescent γ-H2AX foci, γ-H2AX protein expression and micronuclei assay, demonstrate that VND3207 can effectively decrease the initial DNA double-strand break level as well as increase the cellular DNA repair capacity and reduce the residual damage level. The effective concentration is as low as 10~20 mol/L. In conclusion, VND3207 has radioprotective effects on cell survival and genomic stability against the irradiation of α particles, and it is of value to develop radioprotective drugs against high LET radiation.

Purification and Recovery of R-phycoerythrin and R-phycocyanin from Polysiphonia urceolata under Different Ammonium Sulfate Precipitation Conditions

Science & Technology Review. 2010, 28 (04): 37-41. ;  doi:
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Abstract ( 852 )
Phycobiliproteins are a family of natural pigment proteins with wide applications and promising market prospects, but their extraction and purification is difficult. Extraction optimization plays an important role in the recovery and purification of the final phycobiliproteins. In this paper, ammonium sulfate saturation, precipitation frequency, ammonium sulfate fractionation are employed to extract R-phycoerythrin and R-phycocyanin from marine red alga Polysiphonia urceolata. The results show that the yields of RPE and RPC are increased with increasing ammonium sulfate saturation. At 60% saturation, their yields reach the highest, up to 91.59% and 97.98%, respectively. 20% saturation could still precipitate 47.3% of RPE and 24.8% of RPC. The purity of RPE is decreased with increasing salt concentration. However, RPC purity is increased with increasing ammonium sulfate saturation, at 45% saturation, the purity reaches the highest, and then slowly decreases as the saturation further increases. During the saturation of 20%~40%, the recovery ratio of RPE and RPC increases with increasing salt concentration; at 40%, the ratio reaches the highest, then is stabilized above 40%. The twice ammonium sulfate precipitation is better than once for RPE and RPC extraction, their yields fall, but their purity is increased. Ammonium sulfate fractionation could significantly increase the purity of RPE and RPC, by 122.42% and 18.67%, as compared to one-step salting, but their yield is decreased significantly. So 60% saturation of ammonium sulfate is suitable for extraction of RPE and RPC from Polysiphonia urceolata, twice salting and two-step fractionation are good for purity increasing, but the first fractionation saturation of ammonium sulfate should be below 20%. This study can be a help for the phycobiliproteins purification.

Photosynthetic Physiological Characteristics of Two Species of Agropyron

Science & Technology Review. 2010, 28 (04): 42-46. ;  doi:
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Abstract ( 594 )
The photosynthetic physiological characteristics of two species of Agropyron introduced and cultivated under dry conditions were measured by Li-6400 portable photosynthesis system. The results show that the diurnal variations of net photosynthetic rates have double peaks, with the first peak at 10:00, and the second at 16:00, with "noon break" at 14:00 obviously because of constraints caused by stomata, and with PAR as an indirect factor; the diurnal variations of transpiration rate and stomata conductance also have double peak, with the same peak times as the net photosynthetic rate; the diurnal variation of intercellular CO2 concentration is roughly in a V-shape, with the minimum at 14:00; the diurnal variations of leave's water pressure deficit of two species are in the same trend, while the diurnal variations of water use efficiency are in the opposite trends; the averages of these photosynthetic physiological parameters of Agropyron mongolicum are higher than those of Agropyron desertorum. Ca and Ta have a greater effect on the diurnal dynamics of Pn of A. mongolicum, Ca and RH have a greater effect on the diurnal dynamics of Pn of Agropyron desertorum, while Ca and RH have a greater effect on the diurnal dynamics of Tr of two species, Gs and the VPD have a greater physiological effect on the diurnal dynamics of Pn and Tr of two species.

Subdivision of Blue Water and Green Water in the Virtual Water Strategy

Science & Technology Review. 2010, 28 (04): 47-54. ;  doi:
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Abstract ( 1640 )
As an important basis for the rational allocation of regional water resources in wider fields, it is necessary to subdivide virtual water resources into blue water and green water, and evaluate the water resource amounts saved through the virtual water strategy that can be made available for other industries except agriculture and stockbreeding. This paper evaluates the blue water resource and the green water resource in the virtual water strategy in Beijing, according to the subdivision model of blue water and green water. The results show that within the virtual water resources consumed by main crops, in cases of taking into consideration of soil water storage and not taking into consideration of soil water storage, the blue water resources consumed by main grains in Beijing are 6.21×108m3 and 6.29×108m3 in 2007, respectively, both more than the green water resources consumed by main grains at the same time. The virtual water import and the blue water import through grain trade are increased significantly since 1999, and the highest amount of the blue water import is 38.80×108m3, and the proportion of the blue water import through food trade in the corresponding real water resource is higher than 50% in Beijing from 2001 to 2007, which indicates that the virtual water strategy has played an important part in solving the problem of water scarcity in Beijing during the past several years, and the subdivision of the blue water and the green water in the virtual water strategy can provide some helpful insight for the rational allocation of regional water resources in wider fields.

Band Structure of 2D Air-hole-type Square and Triangular Photonic Crystal Under Vertical Incidence

ZHOU Li-Bin
Science & Technology Review. 2010, 28 (04): 55-58. ;  doi:
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Abstract ( 694 )
The eigenmatrix for the propagation of light in a photonic crystal is obtained by the plane-wave expansion method. Dispersion curves of photonic crystals of two dimensional square and triangular lattices composed of circular air cylinders are calculated numerically under vertical incidence, together with the dispersion curves of two dimensional photonic crystals with different radii of holes. It is shown that the first band gap of E wave of the two dimensional square lattice divides in direction <11>, and so does that of H wave; in direction <10>, the first band gap of E wave is a little smaller than that of H wave and becomes wider with the increase of the radius of the hole; on the other hand, that of H wave becomes wider first then decreases. The edge of the first band gap in direction <11> of two dimensional triangular lattice, different from that of the square lattice, is at point (0.5, 0.5) instead of at point (1, 1); the center frequency is smaller than that in direction <10> and the band gap is larger than that of the square lattice. In direction <10>, the first band gap of E wave is a little wider than that of H wave, and their variation trends are completely different: the first band gap of E wave becomes wider with the increase of the radius of the hole at the first and then decreases, but that of H wave is getting wider all the time.

Nonlinear Dynamics of a Composite Laminated Cantilever Plate

Science & Technology Review. 2010, 28 (04): 59-63. ;  doi:
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Abstract ( 661 )
The nonlinear dynamics of composite laminated cantilever plates subjected to in-plane and transversal excitations is investigated in this paper. With the wing flutter of a flying aircraft as the background, based on the Reddy's high-order shear deformation theory and von Kármán type equations for the geometric nonlinearity, the nonlinear governing partial differential equations of motion are derived for the composite laminated cantilever plate subjected to in-plane and transverse excitations by using the Hamilton's principle with considerations of the effects of higher-order transverse shear deformation, nonlinear geometry deformation and transversal damping. The Galerkin approach is utilized to transform the nonlinear partial differential governing equations of motion for the composite laminated cantilever plate to a two-degree-of-freedom nonlinear system. The principal parametric resonance, the 1/2 subharmonic resonance and the 1:2 internal resonance are considered. The method of multiple scales is employed to obtain the four-dimensional averaged equations of the composite laminated cantilever plate subjected to in-plane and transverse excitations. The dynamical behaviors of the cantilever plate under combined in-plane and transversal excitations are investigated with numerical simulations of the averaged equations. The two-dimensional phase portrait, waveform and three-dimensional phase portrait are obtained as results of the nonlinear dynamic behaviors of the composite laminated cantilever plate. The results of numerical simulations demonstrate that there exist one-periodic, multi-periodic and chaotic motions of the composite laminated cantilever plate.

Parallelization of DSMC Method on Unstructured Grids for Hypersonic Rarefied Gas

Science & Technology Review. 2010, 28 (04): 64-67. ;  doi:
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Abstract ( 810 )
Unstructured triangle grid is used as the basic grid cell. Based on the variable hard sphere (VHS) model, the Borgnakke-Larsen phenomenological model, the chemical reaction model of Bird and the Cercignani-Lampis-Lord(CLL) gas surface interaction model, the rarefied gas Direct Simulation Monte-Carlo (DSMC) codes in Fortran are developed, which can simulate the relaxation of internal energies, the thermodynamic non-equilibrium and the chemical reaction non-equilibrium. To take advantage of the parallel computation on multi-core computers, the parallel OpenMP model is incorporated into the DSMC method, and the unstructured DSMC parallel program can process numerical simulations on multi-core computers. The hypersonic airflow past cylinder is simulated in different cases of different rarefied regions to see the effect of thermal non-equilibrium. The numerical results have verified the rationality of the DSMC parallel program. For example, the computation efficiency after parallelization is nearly doubled using double-CPU or dual-core computers.

Spatial-temporal Features of Abnormal Surface Latent Heat Flux Before the Qinghai Haixi Earthquake Sequence in 2009

Science & Technology Review. 2010, 28 (04): 68-73. ;  doi:
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Abstract ( 698 )
Remote sensing technology can be used to obtain accurately the variation of Surface Latent Heat Flux(SLHF), therefore, can serve as a means for long-term monitoring of SLHF for tectonic activities and earthquakes(EQ). In this paper, the SLHF data from NCEP are used to analyze the variation of latent heat before Qinghai Haixi Ms 6.4 earthquake on August 28, 2009 and its aftershocks. Several conclusions are drawn. (1) SLHF anomaly started to appear around the epicenter 6 days before the main shock. Then it continued to develop in intensity and extent, and moved to the coming epicenter. It disappeared when the main shock came. The maximum SLHF reaches 70W/m2. (2) SLHF anomaly also appeared before aftershocks, but in a different spatio-temporal evolving process. The evolving processes are multi-revolving with cycling features. (3) There is a good spatial corresponding relation between SLHF anomalies and the epicenters. The strong abnormal area corresponds to the main shock, while a weak abnormal area corresponds to aftershocks. Particularly, the SLHF anomaly is located exactly at the coming epicenter in Dulan aftershock. This case implies that SLHF anomaly before earthquakes should be a Lithosphere-Coversphere-Atmosphere (LCA) coupling effect in the earthquake preparation period, especially, in the impending-earthquake process. The features of SLHF anomaly before the main shock and aftershocks in seismic active regions might be important in future researches, and can be used in earthquake monitoring, prediction, hazard warning and disaster reduction.

Range of Rock Movement in Transition from Open Pit to Underground Mining Determined by Numerical Method

Science & Technology Review. 2010, 28 (04): 74-79. ;  doi:
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Abstract ( 669 )
With the depletion of shallow mineral resources, many open pits have been already or shall soon be switched to underground mining. The safety design of open pit stoppage combined with the opening of underground mine involves many problems. In this paper, FLAC3D is used to systematically analyze the rock layer movement and deformation. Surface displacements of ore-bodies II and IV at different mining levels are discussed. With the determination of parameters of rock layer movements, the open pit slope stability of Yongping copper mine is analyzed. The corresponding movement characteristics of rock mass, maximal vertical and horizontal displacements as well as rock movement angles are obtained. Results show that the influence of ore-body II on the rock layer movement is far greater than that of ore-body IV. The maximum vertical and horizontal displacements all occur in the rock mass located on the eastern slope of ore-body II. The reasonable mining sequence should be ore-body IV first and ore-body II second. A part of the model area is in the state of breakage and limit stability. However, the open pit slope is in an integral stability state as the mining advances. It is shown that the filling method used in the next stage in the mine is feasible. The rock layer movement during the open pit stoppage combined with the opening of the underground mine, simulated by using FLAC3D, gives a true picture of the stress and displacement states of the rock mass.

Characteristics of Depositional Facies Badaowan Formation, Jurassic of Jian 188 Well Block, Baikouquan Oil Field

Science & Technology Review. 2010, 28 (04): 80-87. ;  doi:
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Abstract ( 778 )
Guided by the sedimentary geology and well logging geology, this paper studies the drilling data, the well logging data, and the well cores and outcrop data of more than 170 wells in Jian 188 well block, Baikouquan oilfield. The Badaowan Formation is divided into 12 substrata according to the correlation methods of sedimentary cycles, index horizons and the similarity of the resistivity curves. The sedimentary facies of each substratum is analyzed and the Badaowan Formation is found to be a braid river sedimentary facies developed in a humid-half arid climate and environments. Three sedimentary subfacies are developed in Badaowan Formation: the main river channel, the branch river channel and the fluvial-flood plain; four sedimentary microfacies are developed in Badaowan Formation: the channel, the channel bar, the flood plain and the marsh. The main river channel and the branch river channel are mainly developed in J1b8-5~J1b7 substrata, and the provenance comes from the northwest of the target area. The river channel and the flood plain are mainly developed in J1b6~J1b3 substrata, and the provenance comes from the northwest and the north of the target area. The marsh is mainly developed in J1b2~J1b1 substrata, and the provenance comes from the northwest of the target area. The arid climate prevailed when the lower Badaowan Formation was deposited and it became humid when the upper Badaowan Formation was deposited. The Badaowan Formation has undergone an integral aggression-regression process according to the comprehensive analysis of the sedimentary evolution history.

Microcosmic Composition of Crude Oil Emulsion

Science & Technology Review. 2010, 28 (04): 88-92. ;  doi:
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Abstract ( 717 )
The emulsification influences the result of oil recovery to a great extent in the process of chemical flooding. However, the mechanisms of how the oil recovery is influenced by the type, size and composition characteristics of the emulsion remain a problem to be studied. Laser Confocal Scanning Microscope(LCSM)with its high amplification and high resolution is used in this paper for that purpose. The microstructure in depth of the sample can be observed accurately. Three - dimensional image can be rebuilt by serial layer scanning. Therefore, the type, size and other characteristics of the emulsion can be analyzed without damaging the crude oil emulsion. According to the tracking test results, including the oil composition, the oil-water ratio, average particle size and the viscosity of the produced emulsion from pilot fields, the simulated emulsion can be made under the laboratory conditions by inversion method and identified by LCSM. Results show that emulsion can be prepared precisely in laboratory by inversion method with similar microcosmic compositions of the crude oil emulsion from pilot fields. Liquid membrane of the W/O emulsion is shown to be mainly composed of saturated hydrocarbon and asphaltene, while the liquid drop is filled with nonhydrocarbon and aromatic hydrocarbon in discontinuous shape.

Microcosmic Composition of Crude Oil Emulsion

Science & Technology Review. 2010, 28 (04): 93-96. ;  doi:
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Abstract ( 626 )
In order to explore the Panhe structure of Huimin depression, and to extend the exploration to deep zones, the structural features and the trap distributions of deep zones in the Panhe structure of Huimin depression are studied by using the recent 3D seismic data. Reservoir-forming conditions in deep zones in the Panhe structure, the reservoir types and the controlling factors of hydrocarbon accumulation are analyzed based on oil-sources, reservoirs and conditions of hydrocarbon accumulation. It is shown that two faults with NEE and NNE trends were developed, the fault extending towards the north was developed in the early-stage, which is the key of the local trap forming, the fault extending towards the south was developed in the late-stage with the long-term fault activity, which is the main controlling factor for oil & gas migration and reservoir-forming. The oil-gas generated in the Linnan sub-sagging was accumulated into the trap of the Panhe structure as a fault system by stepping migration and late migration. Complex fault block reservoirs with reverse fault blocks were formed, which shows high exploration potentiality, and the reverse fault step zone is the most favorable exploration target.

Proposed CO2 capture technology in China

Xue ZHAO
Science & Technology Review. 2010, 28 (04): 97-100. ;  doi:
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Abstract ( 750 )
The emission of CO2 in China ranks top around the world. China has the responsibility to dedicate more in CO2 capture technology. The aim of this paper is to find a proposed CO2 capture technology in China. As in China, pulverized coal plants are exist commonly. There are not plans for new plants to be built with carbon dioxide capture and storage systems in short terms. We focus our purpose on the retrofit of exist pulverized coal plants. There are 3 main kinds of technologies including pre-, post and oxy-fuel combustion for CO2 capture. After the comparisons between CO2 capture technologies, we concluded that oxy-fuel combustion performs better than other technologies both on technologic and economic evaluations. The total capital cost for retrofitting a conventional PC plant with CO2, SO2, NOX, and Hg removal equipment installations (post-combustion) is more than the Oxy-FGR modification. The total O&M cost of an Oxy-FGR retrofit is about half that of the MEA retrofit. Oxy-fuel combustion would be a better choice for exist pulverized coal plants.
Reviews

The Roles of Glucuronidation in Drug Metabolism

Science & Technology Review. 2010, 28 (04): 101-109. ;  doi:
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Abstract ( 926 )
Glucuronidation as a major phase II reaction plays important roles in biotransformation, metabolism and disposition of drugs, such as nicotine, morphine, and Tamoxifen used for curing breast cancer. This paper reviews the recent research development in drug glucuronidation. The tissue distribution, polymorphism, and substrate diversity of UDP-Glucuronosyltransferases (UGTs) for glucuronidation, products of drug glcuronidation, and pharmacology and toxicology of glucuronidation for drug metabolism are discussed, together with the risks of de-glucuronidation, the distribution and significances of UGTs in brain, the individual differences, species differences of drug glucuronidation, the analysis methods for drug glucuronides, and different research results obtained for drug glucuronidation. This review will provide some food for thought in understanding the recent developments of glucuronidation in drug disposition and metabolism, and it will be useful for further researches on the drug glucuronidation and metabolism, efficacy and toxic side effects of drugs, and the relation between drug glucuronidation and the occurrence of cancers. It is important not only to understand the roles of glucuronidation in drug metabolism, but also to develop new drugs with high efficacy, quick metabolism, and small risk of side toxic effects.

Impact of Changing Climate on Agriculture in China

Science & Technology Review. 2010, 28 (04): 110-117. ;  doi:
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Abstract ( 1139 )
Under the background of the global climate change, the mean temperature continues to rise in China during the last 50 years, with annual mean surface air temperature being increased by 1.1℃, higher than the global temperature increase; the precipitation trends are not obvious, with large interdecadal fluctuations and significant regional differences; the number of extreme weather and climate events grows. In the future climate change scenarios, the warming amplitude is higher in the northern area than in the southern area, the most obvious warming occurs over Tibetan Plateau, the annual precipitation increases significantly in the north, northwest and north-east of China, with a small increase in the Yangtze River and its southern region. The growth period of rice, maize and wheat will be shortened by climate warming, with decreased yield; climate warming is beneficial to cotton production, and can improve yield and quality of cotton in the north; the triple cropping area will increase by about 22.4%, one-harvest area will shrink by about 23.1%, the crop planting structure and layout in crop varieties will change; the situation of the main crop pests and diseases tends to be worse; climate warming is beneficial to the livestock growth in temperate and boreal regions, but detrimental to the livestock growth and forage in tropical and subtropical regions; there will be reductions to varying degrees of productions of four major economic species and fish catches in China's four sea areas; with the climate warming, various types of natural vegetation in China will move northward, the scope of desertification hazard will expand, soil fertility will decline and the agricultural irrigation water requirement will increase, the conflicts between supply and demand of agricultural water resources will be intensified. China's strategy will include two aspects, mitigation and adaptation, and both should be taken enough attention.

Research Progress of Synthesis of Nonionic Gemini Surfactants

Science & Technology Review. 2010, 28 (04): 118-123. ;  doi:
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Abstract ( 756 )
Gemini surfactants contain two hydrophobic groups and two hydrophilic groups, connected by a linkage close to the hydrophilic groups. They are known to have excellent properties, such as lower critical micelle concentration (CMC), greater efficiency in lowering the surface tension of water and the interfacial tension between water and oil, and better solubility in water than conventional monomeric surfactants. There are many studies on the synthesis and properties of anionic and cationic gemini surfactants, but very few on nonionic gemini surfactants. The nonionic gemini surfactants can be divided into two categories: one is the polyethyleneglycol or phenol ether type gemini surfactant, and the other is the sugar-based surfactant. The synthesis technology and the research progress of the different kinds of nonionic gemini surfactants and their properties are reviewed in this paper. The first method is to insert a spacer between two ready-made amphiphilic groups. The nonionic gemini surfactants can also be synthesized in such a way that the spacer is first combined with two hydrophobic chains, followed by two polar groups. Generally, the spacer is the polyoxyethylene or the polyoxypropylene. The third method is to link the raw materials containing two polar groups by the spacer, and to obtain the nonionic gemini surfactant by adding two hydrophobic chains. In the end of the paper, some suggestions on the development of nonionic gemini surfactants are made for the industrialization of the novel gemini surfactants.

Science & Technology Review. 2010, 28 (04): 124-124. ;  doi:
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Abstract ( 478 )
科技评论

Science & Technology Review. 2010, 28 (04): 125-125. ;  doi:
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Science & Technology Review. 2010, 28 (04): 128-128. ;  doi:
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Focus

Science & Technology Review. 2010, 28 (04): 126-127. ;  doi:
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主编心语

Science & Technology Review. 2010, 28 (04): 133-133. ;  doi:
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走向职场

Science & Technology Review. 2010, 28 (04): 134-134. ;  doi:
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Science & Technology Review. 2010, 28 (04): 136-136. ;  doi:
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Science & Technology Review. 2010, 28 (04): 138-139. ;  doi:
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