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   Science & Technology Review
2015, Vol.33, No. 6
28 March 2015

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Science & Technology Review. 2015, 33 (6): 3-3.
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Abstract ( 381 )

Science & Technology Review. 2015, 33 (6): 6-6.
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Science & Technology Review. 2015, 33 (6): 8-8.
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Science & Technology Review. 2015, 33 (6): 10-10.
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Science & Technology Review. 2015, 33 (6): 120-120.
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Science & Technology Review. 2015, 33 (6): 121-121.
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Science & Technology Review. 2015, 33 (6): 124-124.
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Science & Technology Review. 2015, 33 (6): 128-128.
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Abstract ( 796 )
Foreword

Science & Technology Review. 2015, 33 (6): 1-1.
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Abstract ( 577 )
Spescial Issues

Gaseous and particulate carbonyl compounds in Shanghai ambient air

WANG Fang, FENG Yanli, JIANG Zhiming, QIU Yiqin, CHEN Yingjun
Science & Technology Review. 2015, 33 (6): 13-19. ;  doi: 10.3981/j.issn.1000-7857.2015.06.001
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Abstract ( 725 )
In order to explore the concentration levels and variations of carbonyl compounds in the atmosphere, a filter pack (FP) system was used to collect gaseous and particulate carbonyl compounds simultaneously in Shanghai ambient air. There are three 47 mm filters in the FP system. Particulate carbonyls were collected on the first filter directly and then the gaseous carbonyls were collected on the second and third filters impregnated with PFBHA. The coating amount of PFBHA was 12 μmol, the sampling flow was 4 L·min-1 for 4 hours. The filter samples were extracted by hexane and injected into the GC/MS system. Seasonal and diurnal variations of carbonyl compounds as well as the gas-particle partitioning were studied. The results showed as follows: 1) 15 target carbonyl compounds are all detected in Shanghai ambient air, including 13 mono-carbonyls and 2 dicarbonyls; 2) the carbonyl compounds exhibit significant seasonal and diurnal variations with higher concentrations in summer, the concentrations of gaseous carbonyls reach the maximum at noon while the particle phases achieve the minimum values at the same time; the total concentration of carbonyls is 33.8±15.9 μg/m3 in summer, significantly higher than the levels in winter (10.5±5.0 μg/m3) and spring (14.0±7.0 μg/m3); 3) gas-particle partitioning of carbonyl compounds is found to be positively correlated with ambient temperature while negatively with relative humidity. Compared to the annular denuder-filter pack (AD-FP) system, the FP system is more suitable for field observation.

Characterization of organic carbon and elemental carbon in PM2.5 during summer in Chongqing, China

PENG Chao, TIAN Mi, ZHAI Chongzhi, YU Jiayan, YANG Fumo, WANG Huanbo, XU Liping, ZHONG Jie
Science & Technology Review. 2015, 33 (6): 20-26. ;  doi: 10.3981/j.issn.1000-7857.2015.06.002
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Abstract ( 775 )
PM2.5 samples were collected at three sites located in Yubei, Nan'an and Yuzhong in Chongqing during the summer of 2014. The concentrations of organic carbon (OC) and elemental carbon (EC) were analyzed with a DRI model 2001A thermal optical carbon analyzer using the IMPROVE-TOR protocol. The pollution characteristics of OC and EC at these sites were evaluated, and the sources of carbonaceous materials in PM2.5 were investigated. The average concentrations of OC and EC were (5.8±1.5) and (2.5±0.8) μg·m-3 in Nan'an, lower than those in Yubei ((8.9±3.2) and (4.2±1.6) μg·m-3) and Yuzhong ((8.8±2.2) and (4.6±1.3) μg·m-3). This is consistent with the concentration distribution of PM2.5, suggesting that the emissions of carbon may be more serious in Yubei and Yuzhong. Concentrations of OC and EC in PM2.5 were found to be significantly correlated in Yubei, Nan'an and Yuzhong, suggesting that they may have similar primary sources. For Yubei, Nan'an and Yuzhong, the concentrations of second organic carbon were estimated as (2.0±1.8), (1.0±0.7) and (2.3±2.0) μg·m-3 by OC/EC ratio method during days without rain and high concentration of O3. The ratios of second organic carbon (SOC) in organic carbon (OC) were lower than 30%. The contribution of SOC to total OC was the highest in Yuzhong. This was possibly due to the formation of the urban heat island effect and the obviousness of the heat and radiation effect, which are beneficial to SOC generation through photochemical reaction. By calculating and analyzing the abundances of eight carbon components in PM2.5, it is indicated that motor vehicle emissions are the major sources of carbon components at the three sites.

Characteristics of mass concentration of carbonaceous aerosols over outskirts of Lanzhou during spring

LI Gang, SHI Guangyu, ZHANG Wu, LI Hongyu
Science & Technology Review. 2015, 33 (6): 27-30. ;  doi: 10.3981/j.issn.1000-7857.2015.06.003
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Abstract ( 773 )
To investigate the variation characteristics and the sources of carbonaceous aerosols in PM10 over outskirts of Lanzhou during spring, samples were collected during 17-26 May, 2012. Organic carbon (OC) and elemental carbon (EC) were measured by thermal/optical method using DRI-2001A. The results showed that the average mass concentrations of OC, EC and TC were 2.71, 11.26 and 13.97 μg/m3, respectively. The dust aerosols played a dominant role in increasing the concentrations of OC and EC. Further analysis showed that the local source had a significant effect on the pollution of carbon aerosol during dust storm in Lanzhou. The correlation coefficient of OC and EC was 0.94, indicating the same emission source. The ratio of OC/EC (5.05) suggested a secondary pollution of carbonaceous aerosol in PM10. The concentration of SOC was 3.37μg/m3, accounting for 29.9% of total OC. Factor analysis on 8 components of carbonaceous indicated that coal combustion and vehicle emissions were the major sources of carbonaceous aerosol.

Characterization of chemical composition for fine particle matter collected in different air quality grades in Xi'an in winter

XU Hongmei, CAO Junji, SHEN Zhenxing, LIU Suixin, ZHANG Ting, ZHOU Jiamao
Science & Technology Review. 2015, 33 (6): 31-36. ;  doi: 10.3981/j.issn.1000-7857.2015.06.004
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Abstract ( 841 )
The ambient fine particle matters (PM2.5) were collected from November 2008 till March 2009 (wintertime) in an urban site of Xi'an to compare with the chemical compositions according to the air quality grades guidelines (HJ 633-2012). All of PM2.5 mass concentrations were in excess of the 75 μg/m3 level in the 24 h Ambient Air Quality Standards (GB 3095-2012). The concentrations of PM2.5 mass and their corresponding chemical compositions were elevated to show a generally increasing trend of the AQI except for a few elements. The concentrations of organic carbon (OC) and water-soluble inorganic ions on six-grade days were approximately 4.5 and 2.7 times those of three-grade days. The enrichment factors of anthropogenic elements (e.g., As, Zn and Pb) on six-grade days were 1.6-2.0 times those of three-grade days, while the elements from crustal sources were not observed along with any surge and rule of air pollution levels. PAHs and n-alkanes mainly were contributed by anthropogenic sources. During the occurrence of heavy air pollution in winter, biomass burning and coal combustion emissions showed a larger contribution to PAHs than gasoline vehicle emissions.

Characteristics of aerosol scattering coefficient in autumn Xi'an, China

ZHOU Yaqing, CAO Junji, WANG Qiyuan, LIU Suixin, ZHANG Ting
Science & Technology Review. 2015, 33 (6): 37-41. ;  doi: 10.3981/j.issn.1000-7857.2015.06.005
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Abstract ( 797 )
To investigate the impact of PM2.5 chemical species on light scattering in autumn Xi'an, light scattering coefficient and PM2.5 samples were collected daily in November 2012 at the Institute of Earth Environment, Chinese Academy of Sciences. The PM2.5 water-soluble ionic species (Na+, NH4+, K+, Mg2+, Ca2+, F-, Cl-, NO3- and SO42-) and carbonaceous (organic carbon and elemental carbon) were analyzed to characterize their impacts on the light scattering coefficient. The average PM2.5 during the sampling period was (195.4±83.5) μg·m-3. The average light scattering coefficient was (579±387) Mm-1, with high value at night and low value in the daytime. The concentration of PM2.5 showed a strong correlation with light scattering coefficient, with a correlation coefficient of 0.85. The estimated light scattering efficiency of PM2.5 was 3.09 m2·g-1. Among the PM2.5 chemical species, NH4+, K+, SO42- and OC had a strong correlation with light scattering coefficient, suggesting that they are the main contribution sources for light extinction coefficient. The revised IMPROVE equation was used to estimate chemical extinction (bext), which was lower than measured bsp, wet. Among the PM2.5 chemical species, organics had the largest contribution to light extinction, accounting for 52.3%, followed by NH4NO3 (16.2%) and (NH4)2SO4 (13.7%).

Levels and variations of indoor and outdoor particulate matter concentrations of a high-rise apartment in winter, Xi'an

DONG Jungang, YAN Zengfeng, CAO Junji
Science & Technology Review. 2015, 33 (6): 42-45. ;  doi: 10.3981/j.issn.1000-7857.2015.06.006
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Abstract ( 721 )
Particulate matter (PM) is an important factor of atmospheric haze and indoor air pollutant which affects human health. This paper takes high-rise apartment in one university as an example to monitor the levels and variations of indoor and outdoor PM1, PM2.5, PM10 and TSP. The results show that there is high PM pollution both in indoor and outdoor air, with the concentration of PM10 being (65.5±20.0)~(142.0±16.9) μg/m3, which is lower than the National Indoor Air Standard. Howerver, indoor PM2.5 and PM1 are (52.2±14.3)~(111.5±12.2) μg/m3 and (50.6±13.9)~(108.7±11.9) μg/m3, respectively, i.e., indoor PM2.5 is about 3~5 times higher than the USEPA standard. The dominant PM in indoor environment is fine particle while coarse particle in the outdoor air. The preliminary study shows the height has no direct relation with the PM pollution.

Evolution of indoor aerosol in Emperor Qin's Terra-cotta Museum and its influential factors

LI Hua, HU Tafeng, CAO Junji, JIA Wenting, MA Tao, WANG Chunyan
Science & Technology Review. 2015, 33 (6): 46-53. ;  doi: 10.3981/j.issn.1000-7857.2015.06.007
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Abstract ( 555 )
Long-term measurement results of indoor air quality (IAQ) from 1989 to 2013 inside Pit No.1, the largest display hall in Emperor Qin's Terra-cotta Museum (QTM) were used to evaluate the effectiveness of measures for conservation environment improvement of antiques. By comparing the results of sampling campaigns in 2013 with databases in 1989, 2004-2005, 2006-2007, and 2011, seasonal and inter-annual variations in microclimate and aerosol chemical compositions were incorporated in estimating the probable influences of management of surroundings, tourist flow, excavation and restoration task, and renovation and/or new construction work on IAQ in the QTM. Since the implementation of the environmental policies of 1990s, a significant decrease of indoor particulate matter mass for the QTM has been achieved. The mass concentrations of summer TSP decreased from 540.0 μg·m-3 in 1994 to 172.4 μg·m-3 in 2004, as well as the winter TSP decreased from 380.0 μg·m-3 in 1994 to 312.5 μg·m-3 in 2005. The mass concentration of summer PM2.5 decreased from 108.4 μg·m-3 in 2004 to 65.7 μg·m-3 in 2013, as well as the winter PM2.5 from 242.3 μg·m-3 in 2005 to 98.6 μg·m-3 in 2013. However, it is noted that potential hazards due to the secondary particulate acidic species in indoor air should still be considered to ensure the long-term preservation and conservation of the museum's artifact collection.

Potential sources and health risk of PM2.5-bounded PAHs at the background site at Tuoji Island

WANG Xiaoping, XU Yue, TIAN Chongguo, CHEN Yingjun, ZONG Zheng, LI Jun, ZHANG Gan
Science & Technology Review. 2015, 33 (6): 54-58. ;  doi: 10.3981/j.issn.1000-7857.2015.06.008
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Abstract ( 714 )
Concentration and composition of polycyclic aromatic hydrocarbons (PAHs) were determined for 75 HiVol PM2.5 samples collected at the national station for background atmospheric monitoring at Tuoji Island from Nov. 2011 to Jan. 2013. The results showed that the total concentration of the 16 USEPA priority PAHs (Σ16PAHs) ranged from 4.7 to 41 ng/m3, with an average value of (17±10) ng/m3, and high PAHs concentrations occurred in cold seasons while low concentrations in warm seasons. An integrated approach of air mass back trajectories, molecular tracers, isomer ratios of PAHs and potential source contribution function analysis was used to identify potential sources. It is shown that biomass burning in Shandong Peninsula during summer is the main PAH source while the outflow of coal combustion and mixed emissions from Jing-Jin-Ji and adjacent areas contributes a high PAH level in cold season. The total toxic equivalent of PAHs (BaPeq) at this site ranges from 0.54 to 8.2 ng/m3, with an average of 2.8 ng/m3. Furthermore, the BaPeq levels in 39% of the total samples exceed the national standard of China, indicating the regional characteristic of PAH health risk in the Bohai Rim.

A tunnel test for emission factors of motor vehicles in Xi'an

TIAN Pengshan, CAO Junji, HAN Yongming, ZHANG Ningning, ZHOU Yaqing
Science & Technology Review. 2015, 33 (6): 59-63. ;  doi: 10.3981/j.issn.1000-7857.2015.06.009
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Abstract ( 370 )
In order to study the characteristics of major pollutants emitted by motor vehicles, a tunnel test was carried out in a representative tunnel in downtown Xi'an. Through continuous online monitoring at both entrance and exit of the tunnel, meteorological data, traffic parameters and mass concentration data of PM2.5, CO, NOx, HC and VOCs were obtained. By calculating the emission factors of motor vehicles, it was found that the average emission factors of PM2.5, CO, NOx, HC and VOCs were (0.016±0.005), (1.097± 0.398), (0.159±0.092), (0.179±0.089) and (0.317±0.172) g/(km·veh), respectively. The emission factors varied with time during the day, and the emission factors of PM2.5 were obviously smaller than gaseous pollutants. In addition, the emission factors declined dramatically as compared to the previous study in China, which might owe to the improvement of fuel quality, engine efficiency, exhaust control technology and urban management.

Evolution of nano-particles within a diesel car exhaust plume via TEMOM-LES method

LIU Huijie, YU Mingzhou, YIN Zhaoqin, JIANG Ying
Science & Technology Review. 2015, 33 (6): 64-68. ;  doi: 10.3981/j.issn.1000-7857.2015.06.010
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Abstract ( 801 )
A study on the evolution of secondary nanoparticles in a diesel engine exhaust is presented, coupling the large eddy simulation (LES) and the Taylor expansion method of moments (TEMOM), with the aim to reveal the differences in total particle number concentration, volume concentration and geometric mean diameter of diesel engines from Canada, Singapore, European, USA, Russia, China and Japan. The investigated aerosol system involved nanoparticle diffusion, nucleation, coagulation and condensation. The nucleation model is the binary homogeneous nucleation of water-acid system, which is valid for the engine exhaust dilution conditions. Considering the particle diameter range in the particle evolution, the free molecule regime coagulation formula is used. The particle condensation growth rate is obtained by calculating the arrival and loss of acid molecules at the entire particle surface. Five different diesel fuel sulfur contents, 10, 15, 30, 50, 350 mg/kg, are chosen as the initial conditions to investigate the particle evolution. It is shown that particles mainly form in the exhaust shear layer while the maximum values of particle number concentration and particle diameter appear in the downstream 0.6 m from the tailpipe. It is obvious that the fuel sulfur content has a significant effect on the formation of secondary nanoparticles. The total particle number concentration and total volume concentration are about four and six orders of magnitude smaller in the lowest fuel sulfur standard than those in the highest fuel sulfur standard, respectively.

PM10 and PM2.5 emission control by electrostatic precipitator for coalfired power plants V: Optimization of high voltage power source with 660 MW boiler

MA Yuankun, QIN Song, CHEN Liang, XU Rongtian, WANG Shilong, CHEN Ying, HAN Ping, ZHENG Qinzhen, SHEN Xinjun, LI Shuran, YAN Keping
Science & Technology Review. 2015, 33 (6): 69-72. ;  doi: 10.3981/j.issn.1000-7857.2015.06.011
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Abstract ( 942 )
This paper discusses the optimization of 16 high-voltage power sources for the four-field electrostatic precipitator to achieve energy saving and fly ash emission reduction. With 16 traditional single-phase rectifier-transformers (T/Rs), the PM10 and PM2.5 emissions and the primary power consumption are about 63 mg/m3, 23.9 mg/m3 and 1225 kV·A, respectively. After retrofitting the power sources with 16 ZH type three-phase T/Rs, the PM10 and PM2.5 emissions and the primary power consumption are about 10-16 mg/m3, 2.0-2.5 mg/m3 and 900-1050 kV·A, respectively. For a similar primary energy consumption, emissions for PM10 and PM2.5 are reduced by about 78% and 92%, respectively.

Theoretical investigation on condensation particle counter and its numerical simulation

ZHANG Xin, CHEN Longfei, LIANG Zhirong, GONG Wei, ZHANG Dizhe
Science & Technology Review. 2015, 33 (6): 73-78. ;  doi: 10.3981/j.issn.1000-7857.2015.06.012
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Abstract ( 876 )
This paper reports the theory and modeling of a nanoparticle monitor, the condensation particle counter. A four-point finite difference implicit approach and Crank-Nicolson approach are utilized for the model and nonuniform grids are adopted. The simulated results have revealed that the four-point finite difference implicit approach is in good agreement with the previous studies, while the stability and precision are improved. This paper numerically validates the feasibility of high temperature condensation particle counter, which was proposed by Cambrige to replace the existing particle measurement program. The result shows that the cut-off size is 4 nm, thus eliminating the effect of volatile compounds. At last, the depletion of working medium is verified, which is caused by working fluid condensing on the particles, thus lowering saturation ratio can be safely neglected.

Novel in-situ spectroscopy methods for ambient emission studies

YANG Huinan, WANG Qin, YANG Zhengpeng, CHEN Jun, CAI Xiaoshu
Science & Technology Review. 2015, 33 (6): 79-85. ;  doi: 10.3981/j.issn.1000-7857.2015.06.013
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Abstract ( 817 )
Novel in-situ spectroscopy methods such as incoherent broad band cavity enhanced absorption spectroscopy (IBBCEAS) and tunable diode laser absorption spectroscopy (TDLAS) have been widely used for ambient emission studies due to their high sensitivity, real time, in-situ and high temporal and spatial resolutions. This work illustrates three real measurements of nitrous acid radical formation, aerosol extinction and multi-parameters of ammonia liquid film. It is conclusively shown that to develop and combine both methods will boost measurement of both atmospheric radical and aerosol extinction, as well as the studies of heterogeneous dynamical chemistry.

Thoughts on mitigation of smog by weather modification

KONG Jun, SU Zhengjun
Science & Technology Review. 2015, 33 (6): 86-90. ;  doi: 10.3981/j.issn.1000-7857.2015.06.014
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Abstract ( 348 )
Mitigation of smog with the aid of weather modification can yet be regarded as an effective attempt. In this paper, the methods, principles and applications of weather modification carried out to mitigate smog are introduced. And their advantages, disadvantages and key problems are analyzed. Presently, there are three main ways of modifying the weather to mitigate smog, namely artificial precipitation, artificial fog dispersal and physical or chemical methods to eliminate dry haze. Artificial precipitation enhancement and super-cooled fog dissipation technology is relatively mature, but the artificial precipitation operation heavily depends on the geographical background and natural conditions. On the other hand, artificial warm mist elimination is not quite ready yet, and needs to develop more effective warm cloud catalyst. And water spray geo-engineering requires more in-depth theoretical analysis, and needs to combine with experiments to find efficient scavenging of PM2.5. The urban air passage method does not apply to all cities, which is restricted by geographical environment and meteorological conditions. It is necessary, therefore, to speed up the development mode transformation and make more energy-saving emission reduction efforts in order to deal with the problem at its source.
Articles

Structural control of reservoir forming for natural gas hydrate in Sanlutian Well Field, Qinghai

CHEN Limin, CAO Daiyong, JIANG Ailin, QIN Rongfang, LI Jing, LI Yonghong, WANG Weichao
Science & Technology Review. 2015, 33 (6): 91-96. ;  doi: 10.3981/j.issn.1000-7857.2015.06.015
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Abstract ( 350 )
In 2008, practical samples of natural gas hydrate(NGH)were drilled out in the frozen soil region of the Qilian Mountain in the Qinghai-Tibetan Plateau for the first time in China, and since then the Sanlutian Well Field in the Muli Coalfield becomes a research focus. But the lack of studies of the controlling factors of the NGH's formation and storage and the NGH's distribution hinders the NGH's exploration and exploitation. An analysis of the materials taken out of the NGH's boreholes in the Sanlutian Well Field and the well field's structural framework reveals the NGH's formation process in the study area, including the structure's role in controlling the NGH reservoir forming. It is concluded that: 1) a reservoir of the NGH is formed by hydrocarbon gases first, and then the NGH enters the temperature-pressure stable zone with Qinghai-Tibetan Plateau's rapid uplift to form a hydrate reservoir; 2) the study area's structure features of partition and zoning control the NGH's flat spreading; the structural movement decides the middle Jurassic coal measures' sedimentation, the hydrocarbon generation and the temperature-pressure stable zone's formation; the structural shape provides the channels, the cap rocks and the storage areas for hydrocarbon gases' enrichment; the later tectonism destroys the earlier gas reservoir and the NGH reservoir.

Experimental research of hysteretic behavior of high strength reinforced concrete bridge piers under cycle loading

ZHANG Jianxin, RONG Xian, LIU Ping
Science & Technology Review. 2015, 33 (6): 97-100. ;  doi: 10.3981/j.issn.1000-7857.2015.06.016
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Abstract ( 218 )
Four concrete bridge piers are tested under a low cycle loading to study the hysteretic behavior of HRB500 high strength reinforced concrete bridge piers. The effects of the shear span ratio, the longitudinal reinforcement and the stirrup strength grade on concrete bridge pier's failure modes are analyzed. The comparison of the hysteretic behavior between the high strength reinforced concrete bridge piers and the ordinarily reinforced concrete bridge piers shows that with the increase of the shear span ratio and the effective constraint of the stirrup, the deformability is increased, the hysteretic curve becomes fuller and the rigidity degeneration slows down. The hysteretic behavior of the concrete bridge piers with a high strength longitudinal reinforcement and a high strength stirrup, such as the rigidity degeneration and the hysteretic curve, is improved as compared to the ordinarily reinforced concrete bridge piers. The bearing capacity and the deformability of the HRB500 high strength reinforced concrete bridge piers are enhanced.

Distribution of endothelial nitric oxide synthase gene intron 4a/b VNTR polymorphism in Uyghur population

MATYUSUP Dolkun, ABDUKERAM Bupatima, NIZAM Yilihamu, SONG Manshu, BAKE Rabiya
Science & Technology Review. 2015, 33 (6): 101-106. ;  doi: 10.3981/j.issn.1000-7857.2015.06.017
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Abstract ( 827 )
To investigate the distribution of the intron 4 variable number of tandem repeats (4a/b VNTR) polymorphism of the endothelial nitric oxide synthase (eNOS) gene, 99 unrelated Uyghur healthy individuals (including 38 males and 61 females) are selected and tested by means of polymerase chain reaction (PCR)-agarose gel electrophoresis. All subjects are genotyped for the eNOS gene. It is shown that the frequencies of the aa, ab, bb genotypes are 2.02% (4 cases), 22.22% (22 cases), 75.76% (75 cases), respectively. The genotype frequency and the allele frequency are not related to the sex (P=0.194, P=0.382, P>0.05). The single factor analysis of various physiological and biochemical indexes shows that the differences of all biochemical parameters are not statistically significant (P>0.05). In the Uyghur population, the frequency of the aa+ab genotypes is significantly lower than those of the Henan Han population, the Taiwan Han population, the Northern Han population and the Black Brazil population (P<0.05, P< 0.01), but is significantly higher than that of the Guangdong Han population (P=0.050). A comparison of a, b, c three allele frequencies shows that the Uyghur has a significantly different frequency from those of the Henan Han, the Taiwan Han, the Jilin Han, the Guangdong Han, the French and the Black Brazil (P<0.05, P< 0.01). In short, the eNOS gene 4a/b VNTR is in line with the Hardy-Weinbery balance law (χ2=0.017, P=0.991, P>0.05), and the group is representative. It is concluded that there is a significant difference between the Uyghur eNOS gene 4a/b VNTR polymorphism and some ethnic groups.
Reviews

Applications of nanoscale magnetic fluids to sensing systems

PU Shengli, JI Hongzhu
Science & Technology Review. 2015, 33 (6): 107-114. ;  doi: 10.3981/j.issn.1000-7857.2015.06.018
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Abstract ( 934 )
The magnetic fluid is a novel kind of functional materials, with both magnetism and fluidity. It has numerous potential applications to sensors due to its unique features. This paper briefly reviews the progress of applications of magnetic fluids to sensors related to the volume, the flow rate, the angle, the temperature, the current and the magnetic field. Their sensing principles are analyzed. Based on the theory of the geometrical optics and the magnetically tunable refractive index of the magnetic fluid, theoretical derivations and numerical simulations of two kinds of magnetic field sensing systems are conduced, to promote sensor researches and applications based on the magnetic fluid.
Focus

The utilization of urban underground space in Singapore and the lesson that could be learned by China

LI Diyuan, MO Qiuzhe
Science & Technology Review. 2015, 33 (6): 115-119. ;  doi: 10.3981/j.issn.1000-7857.2015.06.019
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Abstract ( 1380 )
Singapore is a country of small land but large population. The population density is close to 10000 per square kilometre. With a severe lack of land resource in Singapore, the government pays a great attention to the development and utilization of the urban underground space. From the 80's in the 20th century, a series of underground space projects in its technical and developmental level have been completed in Singapore. For example, the metro, the underground commercial street, the underground parking, the underground pipe network system, the underground storage cavern, the large public underground space. The development of underground space projects in Singapore has made a remarkable progress both in theory and in practice. The paper first reviews some successful underground space projects and then discusses the technical difficulties encountered in the construction process. The purpose of the paper is to highlight some valuable experiences in both theoretical and practical fields in the urban underground projects. Within the context of the current urban underground space development of large cities in China, some suggestions are made.
News Around

Science & Technology Review. 2015, 33 (6): 7-7.
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Abstract ( 738 )
News Focus

Science & Technology Review. 2015, 33 (6): 9-9.
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Abstract ( 653 )
Forum

Science & Technology Review. 2015, 33 (6): 12-12.
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Abstract ( 758 )
Scientific Community Promotion

Science & Technology Review. 2015, 33 (6): 122-122.
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Abstract ( 580 )
Book Reviews

Science & Technology Review. 2015, 33 (6): 123-123.
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Abstract ( 735 )
Perspectives

Science & Technology Review. 2015, 33 (6): 125-125.
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Abstract ( 706 )
Scientists

Science & Technology Review. 2015, 33 (6): 126-126.
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Abstract ( 729 )
Careers

Science & Technology Review. 2015, 33 (6): 127-127.
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Abstract ( 803 )

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