Table of Content

28 October 2013, Volume 13 Issue 5

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Environmental and Chemical Engineering

Water Quality Simulation and Mitigation Strategy of Seasonal Oxygen-Deficiency in Baihua Reservoir

ZHANG Jing1, LIU Xiao-long2, GAO Yang1, JIANG Yan-xing1, LI Shuang1, LUO Wen-yun1, WANG Fu-shun1

2013, 13(5):  441-447.  doi:10.3969/j.issn.1007-2861.2013.05.001

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Since the 1990s, seasonal emergency of water pollution has occurred frequently in reservoirs on Maotiao River. To understand the mechanism of water quality deterioration, the investigation of Baihua Reservoir was carried out from July 2007 to June 2008. Water temperature, dissolved oxygen (DO) and nutrients were monitored once a month. The water quality analysis simulation program (WASP) was used to simulate water temperature, DO and NH⁺ ₄ . Simulation results fitted well with the monitoring values, indicating applicability of the model. Furthermore, the inflow of the reservoir was regulated within the model. The result shows that efficient seasonal flow regulation plays an important role on the improvement of DO level in the seasonal oxygen-deficiency period.

Performance of Blast Furnace Slag Cement Mixed with Steel Slag

YAN Li-jun1,2, GE Tan-tan1, ZHANG Jie-yu3, ZHU Jun-hong4,YAN Xiao-juan1, HE Chen1, WANG Jun-xi1,HU Xue-feng1

2013, 13(5):  448-453.  doi:10.3969/j.issn.1007-2861.2013.05.002

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Compressive strength tests of concrete specimens were made using different components of steel slag. The pH values of concrete specimens in water was determined after certain curing. Relationship between compressive strength and hydration reaction in various components of steel slag was analyzed. Experimental results show that the optimal steel slag-mixing ratio is 20%. The compressive strength of concrete decreases as the steel slag-mixing ratio is over 30%. The pH values of concrete differs significantly with the steel slag mixed and carbonization time of concrete specimens mainly because steel slag contains a reasonable amount of the low-Fe-Al phase.

Pollution of PFOS in Domestic and International Water and Sediment

SUN Rui, WU Ming-hong, XU Gang, LIU Ning

2013, 13(5):  454-458.  doi:10.3969/j.issn.1007-2861.2013.05.003

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Perfluorooctane sulphonate (PFOS) is a new type of persistent organic contaminants caused by human living and detected throughout the world. PFOS enters into the environment through fluorine- containing wastewater treatment plant discharges, industrial production of PFOS or its precursors, atmospheric deposition, etc. It is mainly distributed in water and sediments. The PFOS contamination occurs mainly in densely populated and industrialized regions, and areas surrounded water treatment plants. The adsorption of PFOS is affected by pH, cation or anion surfactants, and concentration of salts. This paper analyzes recent domestic and international literature and studies PFOS to give a summary of PFOS pollution characteristics in water and sediment environments.

Growth Behavior of Orthorhombic SnO₂ Induced by Mn-Doped SnO₂

WANG Li-jun, CHEN Chen, LIU Yan-yu, CHEN Zhi-wen

2013, 13(5):  459-464.  doi:10.3969/j.issn.1007-2861.2013.05.004

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Tin dioxide (SnO₂) is an n-type semiconductor material with tetragonal rutile crystal structure under normal conditions and displays many interesting physical and chemical properties. Another form of SnO₂ with an orthorhombic crystal structure is known to be stable only at high pressures and temperatures. However, there are limited reports on effects of Mn-doped tetragonal phase SnO₂ on micro/nanostructured characteristics. In this article, micro/nanostructures of Mn-doped tetragonal phase SnO₂  have been successfully prepared with a chemical co-precipitation method. The micro/nanostructural evolution of Mn-doped tetragonal phase SnO₂ under different heat treatment temperatures is evaluated with X-ray diffraction (XRD) and a high-resolution transmission electron microscopy (HRTEM). It is surprisingly found that the orthorhombic phase SnO₂  is formed in Mn-doped tetragonal phase SnO₂ . The obvious diffraction peaks and clear lattice fringes confirm that the orthorhombic phase SnO₂  nanocrystals evidently exist in Mn-doped SnO₂ samples. Experimental results indicate that the XRD peak intensities and crystal planes of the orthorhombic phase SnO₂  decrease with increasing of heat treatment temperatures. Formation of orthorhombic phase SnO₂ is attributed to the lattice distortion of tetragonal phase SnO₂ due to the Mn-doped tetragonal phase SnO₂.

High Purification of Micro-polluted Water in Compound Artificial Wetland with Bio-cord and Wetland Plant

ZOU Lian-pei1, CHEN Fang1, WANG Xin-ze2, SUN Rui-ru1, SONG Zhao-feng1

2013, 13(5):  465-469.  doi:10.3969/j.issn.1007-2861.2013.05.005

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A compound baffle artificial wetland system consisting of new bio-cord paddings and Eichhornia crassipes used hydraulic retention time for 24 hours to highly purify micro-polluted water so that the output of water are improved. The average removal rate of chemical oxygen demand (CODMn) was 24.89% and 22.02% respectively in device A filled with bio-cord and Eichhornia crassipes and in device B only with bio-cord. Besides, the average removal rate of total nitrogen (TN) was 40.80% and 40.73%. For NH⁺₄-N, it was 73.82% and 69.42%, and total phosphorus (TP) was 47.83% and 39.76%. The output water quality in Luoshi River can be raised from the original class VIV to class ⅢⅡ of the quality standard for surface water environment (GB 3838—2002) after purification.

Preparation and Properties of Manganese-Fluorozirconate Composite Conversion Coating on AZ31 Magnesium Alloy Surface

CAO Tie-hua1, CHAI Rui-jie2, HUANG Hong-yan2, CHENG Dan-hong3, YE Gen2

2013, 13(5):  470-473.  doi:10.3969/j.issn.1007-2861.2013.05.006

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A new chromium-free conversion coating on magnesium alloy was prepared. A cast magnesium alloy AZ31 series was used as the raw material. Compact chemical conversion coating was formed on the surface after mechanical polishing, alkaline washing, and chemical conversion. Surface morphology and composition of the coating were analyzed with a scanning electronic microscopy (SEM). Energy dispersive analysis (EDS) Tafel curves and drop corrosion test were used to evaluate the corrosion resistance of the conversion coating. The results show that compositions of coating are magnesium aluminum, oxygen, phosphorus, zinc, manganese and zirconium, and the coating has good adhesion and corrosion resistance.

FGD Process Technology with Sodium Alkaline Method

CHAN Wen-bing, WAN Hao, SONG Gui-dong, GU Xiao-jing, WU Cheng-wu, LIN Zhi-li

2013, 13(5):  473-478.  doi:10.3969/j.issn.1007-2861.2013.05.007

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Experiments of simulated flue gas desulfurization (FGD) were carried out by using ethylene waste alkali liquor as absorbent. The influence of affecting factors including inlet gas temperature, oxygen content in flue gas, ratio of liquid to gas volume, SO₂ concentration at the inlet of flue gas, and velocity of flue gas on the efficiency of flue gas desulfurization was studied. The economic benefit of this process technology used in a plant is analyzed. Experimental results show that desulfurization efficiency reached more than 95% of the process parameters: inlet flue gas temperature of 80~90 ℃, oxygen content of 5%~6% in flue gas, ratio of liquid to gas volume of 3.5 L/m³, flue gas velocity of 3.5~4.5 m/s. When ethylene waste alkali liquor concentration was 2.0% NaOH and 7.2% Na₂CO₃ or much more, the desulfurization efficiency is higher. In addition, ethylene waste alkali liquor had certain foaming tendency at low speeds of the flue gas.

Controlled Fabrication of Highly Ordered Au Nanoarrays as SERS Active Substrates

ZHOU Yi, FU Qun, WANG Sha-sha, ZHANG Hong-chao, LEI Bo, LEI Yong, WU Ming-hong

2013, 13(5):  479-484.  doi:10.3969/j.issn.1007-2861.2013.05.008

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A simple and versatile method for fabricating surface-enhanced Raman scattering (SERS) active substrate with high uniformity, structural controllability, high sensitivity and great stability is reported. The ordered aluminum template formed during the synthesis of anodic aluminum oxide (AAO) film was used as the
concaved matrix. Au nanocap arrays as SERS active substrates were prepared through thermally evaporation. Taking Rhodamine 6G (R6G) as probing molecules, SERS spectra were investigated. The results indicates that these SERS active substrates displayed very strong SERS performances (Raman enhancement factor >1×10⁷). Comparing with the ordinary Au film, the SERS enhancement effect of the Au nanocap array is about seven times stronger at 1 363 cm⁻¹. A 6-month-old sample almost kept the same SERS activity with the newly prepared sample. Such ordered Au nanocap arrays allows application in the detection of chemical and biological molecules with trace amounts.

Bioreduction-Responsive, Enzymatically Crosslinked Injectable Hydrogels

JI Xiao-jun, CAO Ao-neng, JIN Rong

2013, 13(5):  485-492.  doi:10.3969/j.issn.1007-2861.2013.05.009

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Injectable hydrogels are widely employed as biomaterials for biomedical applications. In this study, disulfide-containing dextran-phloretic acid conjugates (Dex-SS-PA) are synthesized. In the presence of horseradish peroxidase, Dex-SS-PA solutions gelate to form bioreducible dextran-based hydrogels via the enzymatic crosslinking method. Physical and chemical properties of the hydrogels including gelation time, gel content and degradation properties are investigated. Live-dead assay and methyl thiazolyl tetrazolium assay are used to evaluate biocompatibility of the Dex-SS-PA hydrogels. It is shown that the higher the dextran molecular weight, degree of substitution of phloretic acid moieties and polymer concentrations, the shorter gelation time and the higher gel content of the hydrogels can be obtained. Besides, the Dex-SS-PA hydrogels are degradable under a bioreducible environment. Cellular viability of NIH 3T3 cells incorporated in the Dex-SS-PA hydrogels demonstrated that they reveal low cytotoxicity. The results indicate that the Dex-SS-PA hydrogels are potentially
useful in biomedical applications.

Synthesis of Core-Shell Polymer Consisting of Polysiloxane and Styrene-Butyl Methacrylate by Concentrated Emulsion Polymerization

JIA Shao-jin1, ZHANG Zhen-qi1, DING Zhen-gang1, LI Rong-yi1, DONG Peng1, LIU Zhen2, JIANG Ping-kai2

2013, 13(5):  493-496.  doi:10.3969/j.issn.1007-2861.2013.05.010

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This paper presents the core-shell composite polymer produced by concentrated emulsion, whose continuous phase contains styrene (St), butyl methacrylate (BMA), etamethyltetraeyelosiloxane (D₄), and azobisisobutyronitrile (AIBN) as initiator. The products are characterized by transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The results show that concentrated emulsion system has good stability and water resistance of the polymer has been greatly improved.

Sludge Reduction Using Bellamya Quadrata

LU Yong-sheng, WU Zu-long, LU Qiong-wei

2013, 13(5):  497-500.  doi:10.3969/j.issn.1007-2861.2013.05.011

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Bellamya Quadrata was selected as the experimental organism during the sludge reduction process. Its predation ability of sludge was used to reduce  sludge. Various reaction factors were investigated, including the amounts of Bellamya Quadrata, feeding rate, feeding time and the initial MLSS (mixed liquid suspended solids). The results indicate that the sludge reduction rate increases with the increase of MLSS and addition of Bellamya Quadrata. Different survival environments contrast experiments indicate that, with enough DO (dissolved oxygen), the result of sludge reduction is satisfactory. Reduction rates of MLSS and MLVSS (mixed liquor volatile suspended solids) are 40.01% and 47.54% respectively, meeting the requirements of sludge stabilization.

Civil Engineering

Bending of Simple-Supported Composite Beam Considering Effect of Adhesive Layer Slip

YANG Xiao, ZHANG Min, LIU Hui

2013, 13(5):  501-507.  doi:10.3969/j.issn.1007-2861.2013.05.012

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For composite beam with adhesive layers, taking slip displacement of the adhesive layer into account and assuming bending of an Euler-Bernoulli beam, the bending of simple-supported composite beam with a uniform load is studied. With fundamental unknowns of deflection and axial displacement, an analytical solution is obtained. Responses of deflection at the beam’s mid-point, slip displacement and shear force of the adhesive layer at the beam end versus the shear modulus and thickness of the adhesive layer are examined for different beam lengths. Further, the natural frequency of a simple-supported composite beam is studied. The expression is obtained with separation of variables. Influences of shear modulus and thickness of the adhesive layer on the first natural frequency are examined. It is revealed that the thickness and shear modulus have a great influence on the deflection of the composite beam and slip  displacement of the adhesive layer. They have a little influence on the shear force of the adhesive layer. The shear modulus of the adhesive layer has a reater influence than that of the thickness on the first natural frequency of the composite beam.

Swelling Characteristics of Gaomiaozi Ca-Bentonite

FANG Lei, SUN De-an, SUN Wen-jing

2013, 13(5):  508-512.  doi:10.3969/j.issn.1007-2861.2013.05.013

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The swelling and collapse characteristics of compacted Gaomiaozi Ca-bentonite are studied by conducting a series of swelling deformation tests, swelling pressure tests and collapse tests. It is found that the swelling pressure increases with the increase of the initial dry density. There is a linear relation  between them in semi-logarithmic scales. The swelling strain due to wetting decreases with the increase of the vertical stress or initial water content, but increases with the increase of the initial dry density. The swelling rate increases with the increase of the initial dry density, but decreases with the increase of  the vertical stress or initial water content. The void ratios at full saturation by three different testing methods are almost the same for the same vertical stress. There is a linear relation between the void ratio at full saturation and the vertical stress in logarithmic scales.

Research on Reliability of Cement Concrete Pavement Based on Road Network System

YIN Xiao, XU Xu

2013, 13(5):  513-519.  doi:10.3969/j.issn.1007-2861.2013.05.014

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Putting the road unit reliability to the road network system, using comprehensive topological index of the road network to determine the importance of each road unit and then to determine the road reliability after repaired, finally it can get the thickness of asphalt overlay by the direct integral method. The example showed that when the thickness of asphalt overlay is less than 35 cm, the road reliability with thickness of asphalt overlay increases and when thickness of asphalt overlay gets to 35 cm, reliability with thickness of asphalt overlay tends to a stable value. Considering the position of each road unit in the road  network can not only make maintained road system reliability maximize, but also make optimal allocation of repair costs.

Influence of Heat Source on Near Field Behavior of Nuclear Waste Repository

QIN Ai-fang, WANG Hai-tang, ZHAO Xiao-long

2013, 13(5):  520-526.  doi:10.3969/j.issn.1007-2861.2013.05.015

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A model test for high-level radioactive nuclear waste repository is carried out. An axisymmetric model for nuclear waste repository of bentonite and rock in the near-field of the nuclear waste repository is established. Considering the thermo-hydro-mechanical (THM) coupled process, temperature field, seepage field and stress field in the near-field after closure of nuclear waste repository, numerical simulation of fully coupled THM is done by using the finite element method (FEM) software Code-Bright with a proper choice of THM constitutive equation. By comparison of different initial heat sources, temperatures of bentonite and rock, liquid saturation, suction and variation of stress in the near field after closure of repository are obtained. The results show that the lower the quantity of initial heat, the better the properties of bentonite and rock.

Management Science

Influences of Driving Pile on Neighboring Tunnel

QIN Shi-wei, ZHOU Yan-kun, MO Long

2013, 13(5):  527-533.  doi:10.3969/j.issn.1007-2861.2013.05.016

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This article begins with simulation of the static pressure pile driving process with FLAC3D based on the cavity expansion theory, and compares the results of numerical simulation and analytical calculation. The calculated values and the trends of numerical simulations and analytical solutions are consistent. Therefore, simulation of the effect of pile driving friction on the displacement penetration method helps produce results close to practice in the entire pile driven process calculation. The pile driving calculation of the resultant effects on the deformation and inner force of the nearby tunnel with depth of 4, 8, 12, 16 and 20 m draws the conclusion that static pressure pile driving has an obvious effect on the deformation of the nearby tunnels. As the depths increases, displacement of the tunnel structure increases, which mainly consists of the displacement in the horizontal direction. The maximum tunnel structure displacement reaches 11.55 mm when the pile driving depth is 20 m. Meanwhile, the pile driving process results in tunnel deflection: counterclockwise (away from the pile) deflection when the pile driving depth is 4, 8, 12 and 16 m; clockwise (toward the pile) deflection when the pile driving depth is 20 m. As the pile driving depth increases, the additional bending moment distribution of the tunnel structure changes gradually from vertically axial symmetry to laterally axial symmetry. The tunnel bending moment turns counterclockwise (toward the tunnel) after pile driving and for most tunnel structures, the absolute values of bending moment tend to decrease.

Material Science

CoO/MgO Solid Solution Catalyst in Mixed Conductor Oxygen Permeable Membrane Reactor

YANG Zhi-bin1, DING Wei-zhong2

2013, 13(5):  534-539.  doi:10.3969/j.issn.1007-2861.2013.05.017

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The catalytic reform performance of CoO/MgO solid solution catalyst for partial oxidation of methane (POM) in a coke oven gas (COG) in  BaCo_0.7Fe_0.2Nb_0.1O_3−σ(BCFNO) oxygen permeable-membrane reactor was investigated. Synthesis technology of the CoO/MgO solid solution catalyst is analyzed. The effect of COG flow rate and air flow rate on the reform performance is discussed. For comparison, the reform performance of NiO/MgO, CoO/MgO and 0.5% RuCoO/MgO solid solution catalyst were studied. The results indicate that the NiO/MgO catalyst is superior to CoO/MgO solid solution catalyst, and the catalytic activity of CoO/MgO with the addition of Ru is greatly improved.

Effect of Grain Boundary Engineering on Corrosion Resistance and Mechanical Properties of Incoloy 800 Alloy

LI Jun1,2, SU Cheng2, ZHANG Lei1, SHAO Yu2, XIAO Xue-shan1, ZHOU Zhi-jiang2

2013, 13(5):  540-544.  doi:10.3969/j.issn.1007-2861.2013.05.018

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This work investigates the effect of grain boundary engineering (GBE) on the corrosion resistance and mechanical properties of Incoloy 800 alloy by scan electron microscopy (SEM), optical microscopy and electrochemical workstation. The resistance to intergranular corrosion and critical pitting potential of Incoloy 800 alloy are improved significantly after specimens are solution treated at 980 ℃ for 15 min, followed by 5% rolling reduction and then annealed at 980 ℃ for 15 min. The tensile strength and σ_0.2  increase slightly, while the elongation rate changes little.

Mathematics.Physics and Chemistry

Improving Efficiency of Axial-Flow Pump under Small Flow Condition

TANG Hui1, CHEN Hong-xun1,2, ZHANG Rui1

2013, 13(5):  545-550.  doi:10.3969/j.issn.1007-2861.2013.05.019

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By applying slot techniques to the impeller of axial-flow pump and choosing an appropriate slotted airfoil as a basis of the slotted impeller, a new type of blade is designed. Based on the commercial CFD software ANSYS CFX, numerical simulation of conventional axial-flow pump and axial-flow pump with slotted blades is carried out to analyze the hydraulic performance and flow characteristics under different conditions. The simulation results show that the slot technique can improve performance of axial-flow pumps under the condition of small flow and decrease pressure pulsation at the impeller’s inlet.  Experiments are performed on two types of axial flow pumps. The obtained hydrodynamic characteristics indicate that an axial-flow pump with slotted blades outperforms conventional axial-flow pumps under small flow conditions, indicating that the slot technique can indeed improve axial-flow pump’s performance.