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   Science & Technology Review
2009, Vol.27, No. 0916
28 August 2009

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Water plays key role in agricultural practice

Science & Technology Review. 2009, 27 (0916): 1-1. ;  doi:
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Abstract ( 488 )
特别栏目

Science & Technology Review. 2009, 27 (0916): 8-8. ;  doi:
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Abstract ( 443 )

Science & Technology Review. 2009, 27 (0916): 8-8. ;  doi:
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Abstract ( 510 )

Science & Technology Review. 2009, 27 (0916): 10-10. ;  doi:
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Abstract ( 483 )

Science & Technology Review. 2009, 27 (0916): 11-11. ;  doi:
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Abstract ( 476 )

Science & Technology Review. 2009, 27 (0916): 12-13. ;  doi:
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Abstract ( 477 )

Science & Technology Review. 2009, 27 (0916): 14-14. ;  doi:
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Abstract ( 459 )

Science & Technology Review. 2009, 27 (0916): 15-15. ;  doi:
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Abstract ( 501 )

Science & Technology Review. 2009, 27 (0916): 16-16. ;  doi:
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Science & Technology Review. 2009, 27 (0916): 17-17. ;  doi:
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Abstract ( 506 )

Science & Technology Review. 2009, 27 (0916): 117-117. ;  doi:
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Abstract ( 484 )

Science & Technology Review. 2009, 27 (0916): 124-124. ;  doi:
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Abstract ( 431 )

Science & Technology Review. 2009, 27 (0916): 139-140. ;  doi:
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Abstract ( 457 )
半月科技风云

Science & Technology Review. 2009, 27 (0916): 9-9. ;  doi:
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Abstract ( 531 )
科技工作者建议

Science & Technology Review. 2009, 27 (0916): 18-18. ;  doi:
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Abstract ( 480 )
Articles

Effect of Arbuscular Mycorrhizal Inoculation on Seedling Growth of Euryodendron Excelsum Under Unsterilized Soil Conditions

Science & Technology Review. 2009, 27 (0916): 19-25. ;  doi:
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Abstract ( 621 )
Euryodendron excelsum H. T. Chang is an endangered species from the family Theaceae endemic to China. It has been reduced to one remnant population with less than 200 individuals in Bajia region of Yangchun County, Guangdong Province. The species is listed as a Grade Two endangered plant for state protection in the Red Data Book of plants in China. A pot experiment was conducted to investigate the effect of indigenous Arbuscular Mycorrhizal (AM) inoculation on the seedling growth dynamics of E. excelsum under non-sterilized soil conditions. The individual height, survival rate, number of leaves and the content of photosynthetic pigments in the leaves were recorded. Moreover, the dynamic life table and survival curve of E. excelsum were also tabulated and analyzed. Results show that AM inoculation of E. excelsum seedling not only can increase the survival rate, but also may promote the height and leaves growth. Furthermore, the content of photosynthetic pigments in the leaves was increased after indigenous AMF inoculation, indicting the improvement of photosynthesis. The seedlings which inoculated AM have no obvious mortality during the first 48 weeks, while the survival curve of the control treatment belongs to Deevey-III, suggesting a high mortality rate in the early seedling growth stage. It is concluded that AM inoculation can promote E. excelsum seedling's growth and increase its environmental fitness. The research results could provide a reference for the effective conservation and population recovery of this critically endangered species.

Preventive Effects of Marine Collagen Peptide on Learning and Memory in Aged C57BL/6J Mice

Science & Technology Review. 2009, 27 (0916): 26-31. ;  doi:
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Abstract ( 1134 )
To observe the preventive effects of Marine Collagen Peptide (MCP) on learning and memory in aged mice, 20-month old female C57BL/6J mice were divided into an aged control group and three MCP-treated groups. The effects on cognitive function, hepatic antioxidative systems, hippocampal morphology and expression of Brain-Derived Neurotrophic Factor (BDNF) were studied after feeding the aged mice MCP (0.22% or 0.44% or 1.32% (wt/wt) in diet) for 6 months. Cognitive functions were assessed using the step-down test and the Morris water maze, respectively. Hippocampal morphology was examined by nissl stain. RT-PCR and Western blot were used to evaluate the expression of BDNF in hippocampus. The results show that their spatial memory and passive avoidance ability were significantly improved when they were fed with MCP. Furthermore, the activity of SOD was significantly increased and the level of MDA was decreased in the 0.44% MCP supplementation group as compared to the aged control group. The expression of hippocampal BDNF was significantly up-regulated in the aged mice treated with 0.44% and 1.32% MCP. However, the number of nissl-positive cell saw no significant difference among all groups. These results suggest that MCP administration has a preventive effect on memory tasks by lowering oxidative damage and up-regulating expression of BDNF.

Space Shading Algorithm for On-orbit Spacecraft

Science & Technology Review. 2009, 27 (0916): 36-39. ;  doi:
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Abstract ( 1035 )
Space shading algorithm for spacecraft is the key link of Meteoroid and Orbital Debris(M/OD) risk assessment. The analysis precision of M/OD risk assessment is mostly dependent on the accuracy of space shading algorithm. The M/OD risk assessment plays a very important role in shielding design and in-orbit safety for spacecraft. For the spacecraft shading problem in orbital debris risk assessment, based on Roberts algorithm and Z-buffer algorithm, a shading algorithm is proposed, which is simple in computation, accurate in results and versatile in applications. Spacecraft structures are often very complex, therefore, in the algorithm, a decomposition of the structure and a related shading are made before a combination operation. The shading of simple spacecraft specified by IADC is analyzed. The exposed areas of spacecraft and each finite element in different yawing directions are obtained. The exposed area of the simple spacecraft is different in different directions. The minimum and maximum exposed areas after shading are 38.91% and 55.27% of the exposed area of the simple spacecraft before shading, which shows that the exposed area of spacecraft has great different in different flight attitude. And changes in spacecraft mission operations, flight rules, and flight planning can reduce meteoroid and debris risks.

Coal Gas Diffusion by Natural Ventilation in Steel Works

Science & Technology Review. 2009, 27 (0916): 40-43. ;  doi:
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Abstract ( 1402 )
The coal gas sudden leakage from the storage tank to air can be disastrous. The diffusion law of coal gas (as light gas) must be carefully studied to prevent the damaging consequence to the workers. This paper presents a simulation of the leakage and diffusing process of coal gas using a simplified two-dimensional plane model combined with LES turbulence model, from which the law of CO concentration versus time and space is obtained. The simulation results show that (1) at the initial stage, the CO concentration near the mouth of leak is more concentrated during disclosure process; (2) when the leak is stopped, the concentration of CO is not immediately reduced and it is followed by a gentle process of development, due to bulky tanks up the wind, which induce the wind turbulence. With the leakage, its leaked CO around the mouth of pressure and velocity disturbance, a disturbance will spread. In the horizontal direction of leakage mouth upward, the CO concentration is significantly higher than that in windward direction. In the natural and ventilated conditions, when leakage stops, the concentrations of CO are not quickly reduced, but take a gentle development process. The results of the study may help to establish the emergency gas leak alarm and preventive measures.

Reliability of Corrosive Gas Pipelines Under Seismic Wave Propagation

Science & Technology Review. 2009, 27 (0916): 44-48. ;  doi:
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Abstract ( 637 )
Water supply pipeline is one of vital projects in the restoration work after earthquake. Against possible secondary disasters under an earthquake, the reliability analysis of gas pipelines under an earthquake is of great significance. In this paper, the axial stress generated by seismic wave propagation, the corrosion models and the pipes' characteristics are analyzed to derive a limit equation of gas pipelines' reliability for the earthquake evaluation. The probability of reliability is evaluated by Monte Carlo method. An analysis on Huainan's gas pipelines shows that the seismic axial stress in the pipeline mainly comes from the peak surface velocity; the seismic and corrosion damages to the gas pipeline are serious; due to the extended impact region of seismic wave propagation, a comprehensive analysis of the two factors is of great significance; the reliability of corrosion water supply pipeline can be effectively enhanced by reducing the variations of the pipe's yield strength, working stresses and other parameters. From an analysis of relative importance of various variables, it is concluded that the wheel load in traffic, the impact factor and the bending moment coefficient are the most important for pipeline safety.

Effect of Nonuniformity of Multi-phase Flow with CO2 on Erosion Corrosion of Pipeline

Science & Technology Review. 2009, 27 (0916): 49-52. ;  doi:
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Abstract ( 698 )
The paper studies the effect of non-uniformity of multi-phase flow with CO2 on erosion corrosion of pipeline. The erosion corrosion tests were carried out in the multi-phase flow loop test system and the non-uniform structure of multi-phase flow in horizontal pipeline was measured by using high-speed digital photography system. The relationship between the erosion corrosion of pipeline and the structure of the flow was examined. The tests of the CO2 corrosion of horizontal pipeline under slug flow show that the bottom surface of the pipe is corroded more distinctly than the upper surface due to the non-uniform distribution of the slug flow. A hydrodynamic model of erosion corrosion of multi-phase flow with CO2 is proposed to determine the corrosion rates of the up- and down- walls of the horizontal pipelines. The wearing degree of corrosion film under the condition of slug flow increases with the increase of flow velocity. The computed results agree with the actual measured results, to show that the non-uniformity of multi-phase flow will result in a more severe corrosion of the bottom of a horizontal pipe than of the upper surface.

Distribution of Elevation and Relief Amplitude in the Eco-environment Seriously Damaged Areas of Wenchuan Earthquake

Science & Technology Review. 2009, 27 (0916): 53-59. ;  doi:
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Abstract ( 792 )
Based on the DEM data, the relief amplitudes of the severest disaster areas of Wenchuan earthquake (including 11 counties) are analyzed. The results show that the southwest is higher than northeast in the area. The regions where the elevation is more than 1 500 m account for 55.34% of the total area, and those with the elevation of more than 3 000 m account for 19.67%. The regions where the elevation is less than 800 m are mainly in the south, and account for 18.59%. The acreage of the region where the relief amplitude within 5 km×5 km grid size is greater than 1 000 m accounts for 23.92%. The acreage of the region where the relief amplitude within 1 km×1 km grid size is greater than 200 m accounts for 44.78%. The elevation of the core disaster area (between the epicentrums of Mw8.0 earthquake and Mw6.4 aftershock) ranges between 650 m and 3500 m. And among this area, the regions where elevation is more than 800 m and less than 2 000 m account for 73.34% of the area. The regions with high elevation and relief amplitude are mainly in the west of the area. The results of analyzing the relief amplitude within 1 km grid size show that the relief amplitude in the south is higher than in the north, and the regions where the elevation is more than 300 m account for 39.07% in the south area and 17.97% in the north area, respectively. The regions where the eco-environment is seriously damaged by the earthquake are mainly in the southwest. The southwest is the center of the earthquake and is also the region with high elevation and relief amplitude, which indicates that there may be some relationship between the damage degree of eco-environment caused by earthquake and the relief amplitude in the area. The acreage of damaged eco-system in the southwest where the relief amplitude is higher accounts for 87.25% of the area, and the acreage of new soil erosion accounts for 68.06%. The chain of causation of the seriously damaged eco-environment in the disaster areas could be described as: strong earthquake+ fault slipping+topography→Geological disasters→damaged vegetation and eco-system→damaged ecological functions.

Simulation of Transient Sediment Transport Processes in a River Network with Water Diversions

Science & Technology Review. 2009, 27 (0916): 60-65. ;  doi:
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Abstract ( 617 )
The confluence of streams is a fundamental process in natural river networks, while a diversion is often related to hydraulic projects. Both the confluence and diversion will cause changes of the discharge, and result in variations of the Quantity of Erosion or Sedimentation(QES). The latter is of practical significance. In this paper, a sediment transport dynamic model, based on the consideration of streams confluence and/or diversion, is proposed to investigate the influence of water diversion on the mainstream. The model considers the mechanisms that the sediment-carrying capability of a stream is modified by the QES and driven by the sediment concentration of the injecting streams. This model can be used to numerically simulate the dynamic behavior of real river networks, to show that water diversion can cause sedimentation to increase. The transient dynamics reveals some interesting characteristics. (1) There is a critical value of the so-called diverting ratio of water at which the state of the segments below the diversion mouth will be transformed from increasing sedimentation to decreasing sedimentation. (2) Water diversion will cause the dynamics of sediment transport more complex, lead to an abrupt change of the erosion-sedimentation state. On each of the segments below the diversion mouth, the sedimentation will oscillate between the states of increase and decrease, as a quick response of the channel to the diversion. (3) If the diverting ratio is fixed and after the quick response, the oscillation extent will decay in the downriver direction. The sedimentation on each of the segments will exponentially decrease with time. (4) There is a maximum quantity of sedimentation on each of segments, as is dominated by a scaling law, that is, the quantity of sedimentation depends exponentially on the number of the segments. These may help us to better understand the nature of the sediment transport process in river networks.

Element Safety Factor in Rock Stability Estimation and Its Influential Factors

Science & Technology Review. 2009, 27 (0916): 66-68. ;  doi:
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Abstract ( 1376 )
Stability evaluation is an important part in the rock engineering design and construction. In order to study the safety of each part of the rock mass, the element safety factor Ke is proposed to estimate the micro-stability of the rock mass. The element safety factor can reflect the stability state of the rock mass under the earth stress. A formula for the element safety factor is derived by a theoretical analysis, and the influential factors for the element safety factor are studied in selected cases, which show that, (1) with the increase of shear strength, cohesion c and friction angle ?准, the element safety factor Ke increases in a linear relation between Ke and the shear strength, and with the increase rate of Ke with respect to cohesion c greater than that with respect to friction angle, so the cohesion has a larger effect on the element safety factor than that of friction angle; (2) the increase of the minimum principal stress will lead to the increase of the element safety factor, while the increase of the maximum principal stress will lead to the decrease of the element safety factor, which is in accordance with the real situation, and they are both in an exponential relation.

Performance Analysis for Rake Receiver of CPPM-UWB System

Science & Technology Review. 2009, 27 (0916): 69-73. ;  doi:
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Abstract ( 644 )
This paper presents a design of an improved signal structure of Chaotic Pulse Position Modulation(CPPM), in view of the fact that the chaotic sequence will lost its chaotic characteristics in the traditional CPPM-UWB system. The performance of the improved chaotic pulse position modulation Ultra Wideband (UWB) communication system is analyzed under the condition without Inter Symbol Interference(ISI), when the system uses Rake receiver of IEEE UWB indoor multipath channel model. The simulation of bit error rate for different Rake receivers on the indoor multipath environment is carried out. The studies indicate that the choice of the number of pulses per bit, the distance between the receiver and the transmitter and the average pulse repetition period have a great influence on system BER. The Rake receiver in the CM1 channel enjoys the best performance under IEEE UWB indoor multipath channel. The computer simulation shows that the performance of ideal Rake receiver is the best though its system is the most complicated. It is also shown that the performance of PRake receiver is better than SRake's and its system is also more complicated than SRake's. The performance of SRake and PRake receivers is improved significantly with the increase of interdigitated number.

Study on Expression Models for Professional Accreditation of Safety Engineering Undergraduate Education

Science & Technology Review. 2009, 27 (0916): 74-77. ;  doi:
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Abstract ( 634 )
The standards for professional accreditation of safety engineering undergraduate education, which included general part (common request), professional part and specific part, was described in brief in this paper. On the basis of summarizing the professional accreditation experimental unit work of safety engineering undergraduate education in 2008, the accreditation work was regarded as a system, which was constituted by the professional accreditation object and the expert group. Behavior of human, states for equipment, environment and management factors for the accreditation information, the mathematical models of information collection, which were based on each expert's sense, apperception, evaluation, judgment and relevant behavior, and unitive information estimation under different standards, were established. Theoretical models of single-directional or multi-directional convergency propagation or volatilization propagation were constructed, in order that both the teachers' and the students' behavior, mode of knowledge propagation could be analyzed and judged, the perceive level of the students could be advanced, and the level of the basic theory, the training-practice ability, and the innovation ability mastered by the students could be appraised, and so that reference sustentation theory could be offered to the professional accreditation of safety engineering undergraduate education. These models make it possible to summarize various opinions of all experts into a combined one. The method is great significant for the professional accreditation of safety engineering undergraduate education.

Selection and Community Structure Analysis of Two New Syntrophic Acetogen Cocultures

Science & Technology Review. 2009, 27 (0916): 78-82. ;  doi:
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Abstract ( 1344 )
Among the bacteria colony in the anaerobic digestion system, the Hydrogen-Producing Acetogens (HPAs) are in between acidogenic fermentation bacteria and those with methanogens in the functional niche. They can digest or translate volatile fatty acids and ethanol, produced by acidogenic fermentation bacteria, into acetic acid and CO2/H2 which can be directly derived by methanogens while methane is being produced. HPAs are quite difficult to be isolated by pure and ampliative cultures due to their accrete characteristics. In order to study HPA's physiological and ecological characteristics and to establish the scientific basis for the development of highly efficient anaerobic biological treatment processes, the syntrophic acetogen cocultures are enriched and selectively bred from the anaerobic activated sludge with methanogens by selective medium, using propionic and butyric acids as the only carbon source. Furthermore, the community structure of the selected syntrophic acetogen cocultures are analyzed by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE). With the medium and the culture condition being improved, two syntrophic acetogen cocultures, namely 7-m-2a and 11-O-1, are obtained. These two cocultures show a high ability in degrading propionic and butyric acids and producing acetic acid, with no CH4 or H2S evolved in both culture systems. The analysis results of PCR-DGGE indicate that specialized syntrophic acetogen bacteria Desulfotomaculum sp. Iso-W2 and its associated bacterias are dominated in the syntrophic acetogen cocultures. The associated bacteria are uncultured bacteria 054E12_B_DI_P58 and Sedimentibacter sp. JN18_A14_H, which can use formate and H2/CO2. The two new syntrophic acetogen cocultures obtained can provide a sample for investigating the physiological characteristics of HPA in depth.

Study on PAHs from the Heavy Chemical Accumulation Area in the Main Stream of the Middle Reaches of Huaihe River

Science & Technology Review. 2009, 27 (0916): 83-88. ;  doi:
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Abstract ( 618 )
As one of the seven major rivers in China, Huaihe River is of great importance in the national economy, in which organic contaminations become a major issue. Polycyclic Aromatic Hydrocarbons(PAHs) are typical examples of Persistent Organic Pollutants(POPs). PAHs are very low in water and easy to be adsorbed by suspended substances and sediments. To study the concentrations and distributions of PAHs in the heavy chemical accumulation area in the main stream of the middle reaches of Huaihe River, suspended substance and surface sediment samples from the section of Huainan and Bengbu were collected in October 2007. By naturally air-drying, the environment samples were extracted with dichloromethane. Then the samples were cleaned up by sodium sulfate coupled with the columns of solid phase extraction. Finally the samples were measured qualitatively and quantitatively by Gas Chromatography/Mass Spectrometry. The data for 16 PAHs in the prior table listed by American EPA were obtained. On its basis, the features of the PAHs distribution in the heavy chemical accumulation area in the main stream of the middle reaches of Huaihe River were studied, especially, the PAHs contents in Sluice Bengbu, which were found to be above the standard in a preliminary study. The results may be summarized as follows. (1) The levels of the studied PAHs are high, from 1 169.44 to 4 048.86 ng·g-1 in suspended substances, and 91.98 to 1 292.52 ng·g-1 in sediments. (2) As single components, Naphthalene is up in suspended substances, while Dibenzo[a, h] anthracene is in sediments. (3) Due to the effects of sampling sites and PAHs itself, the concentrations of PAHs in suspended substances are significantly higher than those in sediments. Meanwhile, globally, the low-ring PAHs prevail over high-ring PAHs in suspended substances, while high-ring PAHs prevail in sediments. (4) According to the quality standard of national ocean sediments, the contents of PAHs in sediments from Sluice Bengbu are seriously overweight. It poses a great danger to the safety of drinking water in Bengbu, as the more PAHs in suspended substances, the greater potential danger will be.

Experimental Study on the Treatment of Acid Scarlet Wastewater with Modified Bentonite

Science & Technology Review. 2009, 27 (0916): 89-92. ;  doi:
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Abstract ( 651 )
Dyes are widely used in industries and their removal from industrial wastewater poses an important issue. A new type of treating agent, chitosan modified bentonite, was prepared. Bentonite had been proven to be a promising material for the removal of contaminants from wastewater, which belongs to the 2:1 clay family. Not only bentonite is abundant in nature, but also it is really an efficient and economic adsorbent for adsorption of pollutants including dyes, oil and heavy-metals. Conventional methods for the removal of dyes from wastewater include adsorption to solid substrates, chemical coagulation, oxidation, filtration and biological treatment. Adsorption is one of the easiest and most effective techniques to remove dilute pollutants among conventional methods. In this paper, the enffluent factors of absorption of acid scarlet in dyeing wastewater on modified bentonite are investigated, including pH value, ratio of modified bentonite mass to wastewater, mixing time and centrifugating time to obtain optimal treatment conditions. The removal rate of chromacity is found to be 97% under the conditions of 30 g/L ratio of modified bentonite mass to wastewater, pH value of 4, 6 min of mixing time and 17 min of centrifugating time. In addition, for better explanation of these results, the natural bentonite and chitosan modified bentonite were critically examined in specific surface area, and with SEM and IR analyses. Results show that structure of bentonite is not changed by adding chitosan, except an increased specific surface area and improved adsorptive capability. It is concluded that chitosan modified bentonite has a promising application in removing acid scarlet from wastewater using adsorption methods.
Reviews

Isolation Method of Dorsal Root Ganglion Neurons of Rats and Their Electrophysiological Characteristics

Science & Technology Review. 2009, 27 (0916): 32-35. ;  doi:
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Abstract ( 663 )
To investigate the isolation method of Dorsal Root Ganglion(DRG) neurons in rats and their electrophysiological characteristics, DRGs were obtained by double enzymatic dissociation. The patch clamp technique was used to record Action Potentials (AP) and sodium currents INa. The results show that a body of round and long DRG, and DRG neurons with middle measures and clear membranes and nucleus was obtained with good refraction properties. APs recorded in DRG neurons consist of five phases and in shape of upward acute triangles, with small static potential and short action duration. INa for DRG neurons, as the peak current density, is equal to (-62.04±4.45) pA/pF, and it is almost inhibited by tetrodotoxin and recovered from the inactivated state. It is concluded that the operations on the body of DRG are simple and easy to handle; DRG neurons are obtained quickly and identified; and the electrophysiological characteristics of DRG neurons are typical and clear. The methods and results may be used in investigations on electrophysiological properties and in medical treatments for diseases in nervous system.

Risk Assessment on Hydrogen Refueling Stations

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Science & Technology Review. 2009, 27 (0916): 93-98. ;  doi:
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Abstract ( 1410 )
With the world wide development of large-scale FCV demonstration projects, the global number of hydrogen refueling stations has increased rapidly in recent years. As a new energy infrastructure, it has always a public concern whether the hydrogen refueling station could ensure enough safety, which becomes one of the biggest obstacles to the further implementations of hydrogen as energy carrier. Therefore, many studies focus the attentions on risk assessment of hydrogen refueling stations, as reviewed in this paper. Firstly, the current studies are discussed in terms of hazard identification, probability analysis, consequences evaluation and risk measurement. The fault tree analysis and the event tree analysis play important roles in risk assessment studies on hydrogen refueling stations due to the lack of failure probability data for hydrogen infrastructure. Secondly, different points of view on damage limit and risk acceptance criteria are analyzed. A unified or widely accepted damage limit criteria and risk acceptance criteria will be a target for future studies. Thirdly, the progress of studies on hydrogen behavior and consequences is summarized to emphasize the need for improvement in risk assessment of hydrogen refueling stations. The experimental studies and numerical researches both contribute to the development of risk assessment on hydrogen refueling stations. Finally, to facilitate the development of hydrogen infrastructure in China, two suggestions are made. On one hand, risk assessment methodology developed by other countries need to be studied. On the other hand, fundamental researches on hydrogen safety need to be strengthened to provide scientific basis to the establishment of hydrogen regulations, code and standards.

Evaluation of Influencing Factors of Biofiltration of Volatile Organic Compounds

Science & Technology Review. 2009, 27 (0916): 99-103. ;  doi:
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Abstract ( 1305 )
With the rapid industrial development, a large quantity of Volatile Organic Compounds(VOCs) is released from various plants and industrial processes. VOCs have become the second most serious pollutants due to their serious harm and extensive source. The increasing presence of VOCs in the atmosphere has been one of today's considerable environmental problems. Conventional VOCs control technologies include incineration, condensation, adsorption, absorption technologies. Biofiltration of off-gases is a relatively new application of biological process in the waste management. Biofiltration used to be used to remove air streams contaminated with low concentrations of biologically degradable VOCs and is recognized as a cost-effective and promising technology with advantages of high efficiency, low cost and limited negative environmental effects. In this paper, a comparison between conventional technologies and biofiltration is made and the development of biofiltration of VOCs and main problems in removal of VOCs by biofilters are discussed. The main influencing factors, such as VOCs characteristics, packing media, water content, pH value, nutrients, bed temperature and microorganisms, are analyzed. Some suggestions on the prospect of biological removal of VOCs are made.

Research Progress on the TiO2/ACF Composite Photocatalytic Removal of Organic Pollutants in Water

Science & Technology Review. 2009, 27 (0916): 104-109. ;  doi:
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Abstract ( 664 )
The preparation methods of TiO2/ACF composite photocatalysts are reviewed. The surface morphology, structural characteristics of TiO2/ACF composite photocatalysts and the effect of concentration, adsorption, photocatalysis and recovery of TiO2/ACF catalyst are analyzed. It is shown that the carbon fiber in the composite affects the concentration of the targeted pollutant and the capture of intermediate products, and may reduce the harmful products of the middle generation.In addition, it has the advantage of suppressing the phase transformation from anatase to mille. The mechanism of the synthetical effect of activated carbon fibers and titanium dioxide is studied based on the morphology and structure of the composite photocatalyst, and the targets, the preparation methods, the loading of TiO2 and other factors which influence the oxidation rate are discussed. A beneficial effect is shown in a practical application of photocatalysis technology to TiO2/ACF composite photocatalysts. The problems that should be solved in future studies are pinpointed.

Research and Application of Sodium Benzoate as Nucleating Agent of Thermoplastic Materials

Science & Technology Review. 2009, 27 (0916): 110-115. ;  doi:
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Abstract ( 840 )
The terms "nucleators", "nucleator compound(s)", "nucleating agent", "nucleating agents" generally mean any additive to polymer, individually or in a combination, that produces nucleation sites for polymer crystals in the transition from its molten state to a solid, cooled structure. Any compound that exhibits such a beneficial effect and property is included within this definition. Such nucleator compounds more specially include dibenzylidene sorbitol types, substituted aromatic phosphate, dehydroabietate-based nucleators and the like. Aromatic carboxylic acids and their metal salts, such as sodium benzoate, are an important type of nucleators. This paper reviews the research and application of sodium benzoate as nucleating agent of thermoplastic materials. Sodium benzoate is made by the neutralization reaction of benzoic acid with sodium bicarbonate solution, and as a dispersion type nucleating agent, it can increase the crystallization temperature of polypropylene(PP) and shorten the crystallization time of PP, and also can change the crystalline form of PP under high-pressure crystallization. When sodium benzoate is used in PET and PEN as a nucleating agent, it plays its role by reacting with polyester(e.g. PET or PEN). It is shown that the improving routes of sodium benzoate nucleating agent are as follows: increasing its purity, reducing its particle size and combining actions with other nucleating agents.

Science & Technology Review. 2009, 27 (0916): 116-116. ;  doi:
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Abstract ( 535 )
Focus

Science & Technology Review. 2009, 27 (0916): 118-119. ;  doi:
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Abstract ( 529 )
科技评论

Science & Technology Review. 2009, 27 (0916): 120-120. ;  doi:
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Abstract ( 538 )

Science & Technology Review. 2009, 27 (0916): 121-121. ;  doi:
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Science & Technology Review. 2009, 27 (0916): 122-122. ;  doi:
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Science & Technology Review. 2009, 27 (0916): 123-123. ;  doi:
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Science & Technology Review. 2009, 27 (0916): 125-125. ;  doi:
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Science & Technology Review. 2009, 27 (0916): 125-125. ;  doi:
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Science & Technology Review. 2009, 27 (0916): 126-126. ;  doi:
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Science & Technology Review. 2009, 27 (0916): 127-127. ;  doi:
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