bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and Characterization of Chitosan-Ethylenediaminetetraacetic Acid/Polyvinyl Alcohol Blend Electrospun Nanofibers
Authors: Charernsriwilaiwat Natthan , Opanasopit Praneet , Rojanarata Theerasak , Ngawhirunpat Tanasait
Published: February 2011

Electrospinning is a technique use to fabricate ultrafine fibers with diameters in the nanometer range. The electrospun fiber mats have high potentials for many applications, due to their high surface area to volume, high porosity and small pore size. In this study, chitosan-ethylenediaminetetraacetic acid (CS-EDTA)/polyvinyl alcohol (PVA) blend nanofibers were successfully prepared using electrospinning techniques without organic solvent. CS was dissolved in EDTA aqueous solution and then blended with PVA solution at various weight ratios. Physicochemical properties of CS-EDTA/PVA solution such as viscosity, conductivity and surface tension were investigated. The morphology and diameter of the electrospun fiber mats were analyzed by using scanning electron microscopy (SEM). The composite structure was characterized by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FT-IR). SEM images showed that the morphology and diameter of the nanofibers were mainly affected by the weight ratio of the blend. Nanofibers were obtained when the CS-EDTA content was less than 50%wt. The average diameter of the nanofibers was 119-223 nm, and this average diameter decreased with increasing CS-EDTA content. In summary, these CS electrospun nanofiber mats may be proper for the drug delivery or wound dressing application.
Appropriate Conditions for Preparation of Nanosized WO3 through High-Energy-Milling
Authors: Chen Chun Huan , Ren Rui Ming
Published: February 2011

In order to synthesize WC-Co nanopowders through an integrated mechanical and thermal activation process, WO3-Co2O3-C nanopowders need to be obtained first. It is critical how to obtain the WO3-Co2O3-C nanopowders efficiently. The effect of processing parameters on the grain size during high-energy-milling of WO3-Co2O3-C mixed powders was studied via X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the grain size of reactants can be effectively decreased with increasing the milling time, rotation speed, and charge ratio. After a certain time milling, both WO3 and C powders achieve nano-level in grain size and mixed homogeneously. The appropriate milling parameters for fabricating nanosized WO3+C+Co2O3 powders are suggested to be 4 to 8 hours of milling time, 400 RPM of rotation speed, and 40:1 to 60:1 of charge ratio.
Spin Polarized Transport through Structures Consist of the Ferromagnetic Semiconductor in Presence of a Inhomogeneous Magnetic Field
Authors: Bamshad Zahra
Published: February 2011

The spin-polarized transport is investigated in a magnetic tunnel junction which consists of two ferromagnetic electrodes separated by a magnetic barrier and a nonmagnetic metallic spacer placed in distance above the two dimensional electron gas (2DEG) in presence of an inhomogeneous external modulated magnetic field and a perpendicular wave vector dependent effective potential. Based on the transfer matrix method and the nearly-free-electron approximation the dependence of the conductance and spin polarization on the Fermi energy of the electrons are studied theoretically the. strong oscillations with large amplitude investigated in spin polarization in terms of the Fermi energy due to the inhomogeneous magnetic field. The conductance in terms of the Fermi energy shows no oscillation in low energy but has a strong pick in middle region. this results may be useful for the development of spin electronic devices based on coherent transport, or may be used as a tunable spin-filter.
Surfactants-Controlled Morphosynthesis of Strontium Carbonate
Authors: You Chao , Zhang Qiang , Zhao Yun , Jiao Qing Ze
Published: February 2011

The controlled synthesis of SrCO3 microstructures with different morphologies, such as flower-like, cauliflower-like and finger-like, were successfully achieved in the presence of mixed nonionic/anionic surfactants polyoxyethylene (20) sorbitan monolaurate (Tween20) and sodium dodecyl sulfate (SDS). Results indicated that SDS/Tween20 complex micelles played important roles in the morphological control of SrCO3 microstructures. Also, the influence of CO32- concentration on the morphology of SrCO3 crystals was investigated and discussed. X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and field-emission scanning electron microscope (FE-SEM) were used to characterize the as-synthesized crystals.
Synthesis and Characterization of Pyrochlore Lead Zinc Niobate Nanopowders Derived from Zn3Nb2O8 Precursor
Authors: Pakawanit Phakkhananan , Ananta Supon
Published: February 2011

A novel approach to synthesis cubic pyrochlore lead zinc niobate-based Pb1.88Zn0.3Nb1.25O5.305 nanopowders with a modified mixed-oxide method has been developed. To ensure a pure phase pyrochlore formation, an intermediate phase of Zn3Nb2O8 was employed as key precursor. The formation of pyrochlore phase in the calcined lead zinc niobate powders has been examined as a function of firing temperature by a combination of TG-DTA and XRD techniques. The morphology evolution has been examined by SEM technique. It has been found that the unreacted PbO and Zn3Nb2O8 phases tend to form together with lead zinc niobate, with the latter appearing in cubic phase. It is seen that optimization of firing temperature can lead to a single-phase Pb1.88Zn0.3Nb1.25O5.305 powders with average particle sizes ranging from 75-400 nm.
Preparation of Porous Nano-Strontium Titanate and its Application in Removal of Heavy Metals from Environmental Water
Authors: Zhang Dong , Zhang Yan Li
Published: February 2011

Porous nano-strontium titanate (PST) was successfully prepared by the reversed-phase suspension polymerization and sol-gel method using reversed-phase suspension droplets as the template, and characterized by XRD and SEM. The ability of the new adsorption to remove lead, cadmium, zinc, copper and nickel ions from water samples was assessed. The results showed that the sorbents were porous, perovskite strontium titanate, and the average particle diameter of crystalloid was 30 nm. The lead, cadmium, zinc, copper and nickel ions were quantitatively retained at pH 5-8; their adsorption capacities of PST for lead, cadmium, zinc, copper and nickel ions were 145.9 mg•g-1, 4.3 mg•g-1, 25.2 mg•g-1, 19.6 mg•g-1and 3.7 mg•g-1, respectively. The adsorbent can be regenerated completely by elution with 0.5 mol•L-1 HNO3. The adsorbent has a promising prospect in removal or enriching of lead, cadmium, zinc, copper and nickel in water.
Adsorption Behavior of Sulfamethoxazole as Inhibitor for Mild Steel in 3%HCl Solution
Authors: Zhang Guang Hui , Yin Lin Liang , Zhang Sheng Tao , Li Xiao
Published: February 2011

The adsorption behavior of sulfamethoxazole as inhibitor for mild steel in 3% HCl solution at 298K has been studied by the methods of polarization curves, electrochemical impedance spectroscopy, weight loss, and quantum chemical calculation in this paper. Results revealed that the sulfamethoxzole acted essentially as the mixed-type inhibitor, and the spontaneous adsorption process involved in both chemical adsorption and physical adsorption. In addition, the adsorption of inhibitor on the steel surface followed Temkin adsorption isotherm model. However, the repulsion among the neighboring adsorbed molecule, as well as the single adsorption center of benzene ring, leaded the failure to form ideal protection film on the metal surface.
Performance Tests of Surface Burning for Firestop Materials
Authors: Kao Shih Feng , Wu Yu Shiang , Huang Chi Jan , Kuo Tsung Min
Published: February 2011

To prevent improper design and construction of fire compartments through-penetration in buildings, and in order to reinforce public building safety management, all beams, pillars, ceilings, floors, doors, walls, and interior decorative materials must have fireproof properties. Moreover, cable conduits, water pipes, and air ducts located in through-penetration sites within buildings should be properly designed to block the spread of smoke and hot air, thus, reducing losses due to fire disasters. This study used common firestop materials, such as firestop sheets, mineral wool, and two-pack fire barrier foam to conduct 10-min surface burning tests on individual substrates. The flame spread distance and smoke per minute were measured and recorded in order to calculate the Flame Spread Index (FSI) and Smoke Developed Index (SDI). The results showed that all three firestop materials meet with the ASTM E84 Class A.
Influence of Fly Ash on Crack Resistance of Mass Concrete
Authors: Wang Jun , Liu Shu Hua , Yang Wen
Published: February 2011

Crack will not only do harm to structure of concrete but also destroy durability of concrete project. The influence of fly ash on crack resistance of mass concrete was studied in this paper. We can decrease brittleness of mortar, elastic modulus, dry shrinkage, adiabatic temperature rising, autogenous deformation and increase creep of concrete by adding fly ash, and present relationship between content of fly ash and elastic modulus of concrete. In short, we can improve crack resistance of mass concrete by adding fly ash.
The Concrete Structure Strengthen Technology and Engineering Application
Authors: Li Jun Hong
Published: February 2011

In this paper, the background of concrete structure strengthen is described, and several common methods of strengthening concrete structure in current construction are introduced. Also the advantages and disadvantages application of reinforcement methods are discussed. so as to valuable experiences for strengthening reinforced concrete structures are accumulate. Both the advantages and disadvantages of the reinforcement methods are described in detail. For example, the increasing cross-section reinforcement method, the replacing concrete reinforcement method, the bonding steel reinforcement method, the pasting steel reinforcement method, the pasting fiber reinforced plastic reinforcement method and so on. And so many accumulated experiences are provided for later strengthening reinforced concrete structure, and the process of strengthening concrete structure is improved.
Experimental Investigation into the Impact of Polypropylene Fibers and SRA on the Early Crack Resistance of Concrete
Authors: Xie Xian Song , Tian Fang , Hong Yi Hong
Published: February 2011

Early shrinkage of concrete includes plastic shrinkage before the final setting, drying shrinkage during hardening process and autogenous shrinkage. Concrete drying shrinkage which is caused by evaporation is a major factor for the concrete volume change. By ring constrained test and free shrinkage TONCEN test, this paper studies the impact of polypropylene fibers and SRA on the shrinkage properties of concrete at the early age. The test shows that the polypropylene fibers and SRA can significantly reduce the early shrinkage of concrete, and SRA works more evidently than polypropylene fibers.
Experimental Research on the Mechanical Parameters of Frozen Pipes under Low Temperature
Authors: Li Dong Wei , Liu Hai Yan , Fan Ju Hong , Wang Ren He , Luo Bi Juan
Published: February 2011

We carried out experiments of the mechanical properties of frozen pipes under different temperatures (-5°C, -10°C, -15°C), obtained axial tensile stress - strain curves of the steel and performance of the overall bending under low temperature conditions. The results showed that: the freezing pipes bending capacity increased with the decrease of temperature, but the stiffness was decreased with the decreasing temperature; the steel yield strength and ultimate strength were both increased with the decrease of temperature, the elongation and sectional shrinkage were decreased with the decrease of temperature. The test results provided the basis for the further research of frozen pipes’ ductile-brittle transition, fracture and other acts in low temperature, and provided reference for the selection of frozen pipe and engineering design.
Effect of Ground Phosphate Slag on the Resistance to Chloride Ion Penetration of Concrete
Authors: Ye Jian Xiong , Wang Ye Jiang , Zhao Shuang , Yang Ming Chao , Yang Chang Hui
Published: February 2011

The permeability resistance of concrete with ground phosphate slag(GPS) against chloride ion penetration was tested according to ASTM1202 and by nitrogen adsorption method. Test results show that by adding ground phosphate slag to concrete, the chloride diffusion coefficient of concrete decreases, and the permeability resistance of concrete against chloride ion penetration increases with improvement of its pore structure. The pores in concrete are refined and the percentage of the pores with diameter less than 20nm in concrete increases. The improvement of pore structure of the concrete by ground phosphate slag is much better than that by the ground granulated blast furnace slag or fly ash, while the addition is 30 percent. The ability of additive to improve the permeability resistance of concrete against chloride ion penetration is in following order: fly ash > ground phosphate slag > ground granulated blast furnace slag.
A Study of Interfacial Transition Zone in Lightweight Aggregate Concrete
Authors: Chen How Ji , Lin Chien Kuo , Tsai Wen Po , Liu Te Hung
Published: February 2011

If concrete is observed at the microscopic level, it can be seen to contain many interfacial transition zones (ITZ), resulting in the weakening of its mechanical properties; as the physical properties of lightweight aggregates (LWA), such as their high absorption, are clearly different from those of normal weight aggregates (NWA), they may lead to variations in the ITZ of lightweight aggregates concrete (LWAC), making its mechanical behavior different from that of normal concrete.This study takes three types of LWA with different rates of absorption as its subjects in order to examine the effects of LWA absorbency on ITZ. The main variables tested include water/binder (W/B) ratio, amount of fly ash substituted for cement, and the saturation states of the four types of LWA, with three different types of microscopic tests used to observe the microstructure of ITZ in concrete, and analyze and compare their differences with ITZ in concrete made with NWA. The results of the study indicate that in LWAC, ITZ with weaker tensile strength did not appear around highly absorbent LWA; only the sample group with a W/B ratio of 0.29 did not show apparent absorption due to the higher viscosity of the mortar, resulting in a slight downward trend in tensile strength, but it was still superior to the tensile strength of ITZ in typical NWA.Observation using scanning electron microscopy (SEM) found that inner pores and cracks of ITZ in LWAC were all smaller than in NWC; X-ray diffraction (XRD) tests indicated that the amount of CH crystals in ITZ was greater than LWAC; and microhardness testing found that microhardness values were higher closer to the surface of the LWA, with some even exceeding that of concrete. The increase in the tensile strength of ITZ in LWAC subsequent to the addition of pozzolanic materials was limited; their improvement of the weakness planes formed by ITZ in NWA concrete, however, was more apparent. An LWA has higher water absorbency capacity when in an absolutely-dry condition, which can markedly increase the strength of ITZ; conversely, if an LWA is in saturated surface dry (SSD) condition, its ITZ behave like those of concrete.
Effect of Fly Ash on the Workability of Nondispersible Underwater Concrete
Authors: Niu Ji Shou , Ma Xian Wei
Published: February 2011

Effects of fly ash on the slump, slump loss with time, dispersibility and strength of nondispersible underwater concrete (NDC) were analyzed. The results show that fly ash can increase the fluidity of fresh DNC and reduce the loss of fluidity, but may be disadvantage for improving turbidity, especially fly ash more than certain range. The reinforcement of fly ash takes place at later ages and the amount of fly ash added which has little effect on later strength continues to be increased with ages. The results of field tests also indicate that NDC with 30% fly ash has very small sump loss and good antidispersibility and meets the requirements of compressive strength.
Carbon Sequestration Analysis of Wood Construction Architecture
Authors: Yu Shu Yang , Tan Hai Yan , Weng Xiang Li , Xu Min
Published: February 2011

Carbon in wood accounted for 50% of oven dry weight, and wood construction architecture consumes less energy than any other material architecture. Through using drying of wood, fire-retardant, wood preservative and other protective treatment for the materials of wood construction architecture can extend service life of wood construction architecture and increase carbon storage. This article based on the processing characteristics of wood, estimated carbon storage and carbon emissions of the wood construction architecture, conclude that wood construction architecture has significant influence on the greenhouse effect and the recycling of carbon sequestration.
Comparative Study on Crack Width Prediction for Concrete Flexural Members with GFRP Reinforcement
Authors: Cai Jiang Yong , Liu Ying Ying , Wang Xue Liang , Xiong Jing Liang , Wan Hong Xia , Tu Zhi Feng
Published: February 2011

Fiber reinforced polymer (FRP) bars are being used as an alternative to steel bars to overcome the corrosion problem. Design criteria and methods have to be reinterpreted for its different properties, and several countries have already established corresponding design codes. The method for predicting crack widths of concrete beams with FRP bars provided in ACI440 is based on the method for that with steel bars. Similarly, a modified method based on GB50010 is proposed in this paper to estimate crack widths of concrete beams with FRP bars. Furthermore, the new method together with ACI440 and GB50010 ones are verified by nine test beams in three existing experiments and most of them show a good agreement with the experimental data. Simultaneously, the new method also proves precise and accurate with the same level as the ACI440 one and indicates its potential to estimate crack width in Chinese concrete code system.
Changes in the Bacterial Community Structure under Different DO Concentrations with New Method for Nitrate Removal
Authors: Shao Liu , Xu Zu Xin
Published: February 2011

This study focused on the change of bacterial communities from a new denitrificatin technology where corncob was used as carbon source and the only physical support for microorganisms, under different dissolved oxygen (DO) conditions. The polymerase chain reaction (PCR) and denaturting gradient gel electrophoresis (DGGE) technique was used for extracting DNA from biofilm samples which collected from corncobs. The sequences of several 16S rDNA DGGE fragments were determined, and the dominant bacterial species that were present in each sample were proposed after comparing the results with data of the NCBI Gene Bank. The results indicated that PCR-DGGE technique was successfully used in this study. Clear relationship was found between DO condition and dominant bacterial communities during the experiment. Facultative anaerobic microorganism such as Bacteroidetes and Clostridium were found as dominant bacteria when DO was lower than 1mg/L. And aerobic microorganism such as Bacillus became the dominant bacteria when DO in the water was high than 2mg/L. These bacterial species mentioned above are all main types of denitrifying bacteria reported in other researches. And the results are helpful to explain the phenomenon why high nitrate removal efficiency was always found when DO condition changed. In addition, the results provided some valuable references for studing bacterial communities under different DO conditions.
A Simple New Way to Prepare Cu-Doped Nano-TiO2 with Visible Light Photocatalytic Activity
Authors: Zhang Mao Lin , Li Long Feng , Meng Xiang Dong
Published: February 2011

Cu-doped TiO2 photocatalysts were synthesized by a homogeneous hydrolysis and low temperature crystallization method using tetrabutyl titanate as the titanium source and cupric acetate as the doping agent. The phase structure, composition and morphology of the product were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and Brunauer-Emmett-Teller surface area analysis (BET). The XRD results confirmed that the crystalline phase of all prepared samples was anatase-type TiO2. SEM results showed that the Cu-doped TiO2 were composed of spherical particles with particle diameter smaller than 20 nm. Furthermore, the photocatalytic activity of the Cu-doped TiO2 catalysts were evaluated based on the photocatalytic degradation of methyl orange (MO) in aqueous solution. The results showed that Cu-doped TiO2 had the higher visible-light-induced catalytic activity than the commercial P25 TiO2 powder. The copper content in Cu-doped TiO2 had obvious effect on the visible-light-induced catalytic activity, and the degradation rate of MO could reach 33.7% using Cu-doped TiO2 with a doping level of 1.0 mol% Cu as a photocatalyst under the visible light irradiation for 3 hours.
Synthesis, Physicochemical Properties and Catalytic Performance of a Modified ZSM-5 Molecular Sieve
Authors: Liu Wei Qiao , Li Gong , Tong Hui Juan , Lei Wei Ning , Shang Tong Ming , Lou Zheng Song , He Xiang Hong
Published: February 2011

A modified ZSM-5 molecular sieve was prepared by the combination of recrystallization and carbon template methods. The samples were characterized by X-ray diffraction, N2 adsorption-desorption, NH3-TPD, TEM and SEM. The results show that the modified ZSM-5 molecular sieve has double pore distribution. The diameters of the two kinds of channels are 0.51~0.56 nm and 1.4~1.6 nm, respectively. In addition, the modified HZSM-5 (H-type ZSM-5) sample mainly has moderate strength of acid sites. Finally, the alkylation of benzene with 1-dodecene olefin was used to evaluate the catalytic performance of the as-synthesized modified ZSM-5 on macromolecules. The conversions of 1-dodecene on the modified ZSM-5, ZSM-5 prepared by conventional process and aluminum-containing SBA-15 mesoporous molecular sieve are 96%, 39% and 83%, respectively. And the selectivities of long chain alkyl benzene on those are 97%, 68% and 91%, respectively. The catalytic properties of the modified ZSM-5 on macromolecules are superior to those of ZSM-5 prepared by conventional process and aluminum-containing SBA-15 mesoporous molecular sieve.
Synthesis and Electrochemistry Characteristics of Layered Li[Li(1/3-x)Mn(2/3-x)NixCox]O2 (x = 0.1, 0.15, 0.2, 0.22, 0.25) Cathode Materials for Lithium Secondary Batteries
Authors: Li Zhi Feng , Zhang Qian , Zhong Sheng Wen
Published: February 2011

Li[Li(1/3-x)Mn(2/3-x)NixCox]O2 (x=0.1, 0.15, 0.2, 0.22, 0.25) compounds were synthesized and studied by the X-ray diffraction method and electrochemical techniques. The XRD analysis showed that these compounds could be classified as the α-NaFeO2 structure type. Both a and c parameters decreased linearly, while c/a increased with the increase of Ni and Co content. The first discharge capacity increases with increasing lithium content at the 3a sites in the Li[Li(1/3-x)Mn(2/3-x)NixCox]O2. A Li[Li0.23Mn0.57Ni0.1Co0.1]O2 electrode delivers discharge capacities of 238 mAh/g at C/10 between 4.6V and 2.5V.
The Impact Properties of a Polyurethane Composite Filled with Clay
Authors: Li Jian
Published: February 2011

A polyurethane/clay (PU/clay) composite was synthesized. The microstructure of the composite was examined by scanning electron microscopy. The impact properties of the composite were characterized by impact testing. The study on the structure of the composite showed that clays could be dispersed in the polymer matrix well apart from a few of clusters. The results from mechanical analysis indicated that the impact properties of the composite were increased greatly in comparison with pure polyurethane. The investigation on the mechanical properties showed that the impact strength could be obviously increased by adding 20 wt% (by weight) clay to the matrix.
The Creep and Relaxation of Viscoelastic Polymer
Authors: Wang Ga Ping , Bai Yang , Chen Li
Published: February 2011

Polymers have more complicated properties since they display both elastic and viscous type responses at different strain rates. As the application of polymers increase, a thorough understanding of the mechanical behavior of these materials becomes vital in order to perform innovative and economical designs of various components. The main objective of this paper is to develop an effective method with the use of Laplace integral transform to describe the creep and relaxation properties of viscoelastic polymers. This general approach is on the basis of the integral constitutive functions for viscoelastic polymers, avoiding the use of differential stress-strain relations. Using this method, the time domain stress-stain relation can be easily obtained. As its application, the creep and relaxation properties of the materials are exhibited in the numerical examples.
Impact of Inorganic Salts on Degradation of Azo Dye Using Fe (III)-Modified PAN Fiber Complex as Heterogeneous Fenton Catalyst
Authors: Wang Zhi Chao , Dong Yong Chun , Dong Si Ming , Hong Miao
Published: February 2011

Fe (III)-amidoximated PAN fiber complex was prepared and used as a heterogeneous photo-Fenton catalyst for the oxidative degradation of Reactive Red 195 in water. The nature and concentration effect of inorganic salts on the dye degradation was investigated. Moreover, UV-Vis spectrum was also used to examine the decomposition process of the dye in the presence of the salt. The results indicated that the existence of the inorganic salts limited the photocatalytic degradation of the dye in water. Na2SO4 shows more strong inhibition effect on dye degradation than the other salts at the same conditions. UV-Vis spectrum demonstrated that the decomposition of the aromatic rings in the dye molecules was also reduced in the presence of the salt.
Preparation and Characterization of Metheylphenyl Silicone Oil for Buffer Clay
Authors: Dong Yu Rong , Wang Jian Rong , Guan Rui Fang , Li Guo Zhong
Published: February 2011

In this paper, the buffer clay was prepared by methylphenyl silicone oil mixed with talcum powder, molybdenum disulfide (MoS2) and zinc oxide (ZnO), and the methylphenyl silicone oil was synthesized by the mixture of methylphenyl cyclosiloxane (Ph-D4) and the octamethylcy-clotetrasiloxane (D4) with tetramethyl ammonium hydroxide as catalyst. By ultraviolet spectroscopy (UV), nuclear magnetic resonance (NMR) analysis of the molecular structure of methylphenyl silicone oil was characterized.
Preparation and Characterization of Surface-Modified β-Tricalcium Phosphate/Ploy(L-Lactide) Biocomposites
Authors: Zou Jun , Jiang Xu Bin , Zhang Jing , Shu You , Chen Xuan , Huang Fa Rong
Published: February 2011

A new surface modification method by modifying low molecular weight ploy (L-lactide) (LMW PLLA) onto the β-tricalcium phosphate (β-TCP) superfine particles has been developed. The surface-modified β-TCP is characterized by FT-IR, XRD, digital microscope and contact angle measurement, et al. FT-IR spectra confirmed that LMW PLLA was connected onto the β-TCP surface through ionic interaction. XRD results indicated that the LMW PLLA did not affect the crystalline form of β-TCP, but the XRD patterns of the p-β-TCP showed a little difference with β-TCP. The p-β-TCP particles could be dispersed uniformly in dichloromethane. In contrast, unmodified β-TCP particles are apt to agglomerate after dispersed into dichloromethane. Wet angle measurement showed that hydrolyzed LMW PLLA significantly improves hydrophobicity of modified β-TCP particles. For the preparation of composites, PLLA was mixed with β-TCP and p-β-TCP, respectively, in a ratio of 85/15 (w/w) and moulded into tensile test specimens. Tensile tests showed that mechanical properties were improved, scanning electron microscopy (SEM) exhibited that modified β-TCP is an effective approach to prepare a homogeneous composites, moreover, it indicated a better interfacial phase interaction in the composite with the p-β-TCP. Chemical bonds between filler and PLLA matrix are assumed to be formed by ionic interaction.
Properties Analysis of Organic Montmorillonite (OMMT) Reinforced Polybutadiene Styrene Rubber (SBR) Composites
Authors: Wang Jin Cheng , Zheng Xiao Yu
Published: February 2011

N, N-diamino-N-octadecyl-N-trimethyl ammonium chloride were used as an intercalation agent to treat Na+-montmorillonite and for forming a kind of OMMT. OMMT was analyzed by fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (XRD). Novel polybutadiene styrene rubber (SBR)/organic montmorillonite (OMMT) composites were prepared by SBR and OMMT. Properties such as cure characteristic, tensile strength, elongation at break, abrasion loss and thermal properties were researched and compared. Results showed that SBR/OMMT-10% composite had the best tensile properties.
Synthesis and Electrochemical Performance of Amorphous Nickel Hydroxide Codoped with Fe3+ and PO43-
Authors: Liu Chang Jiu , Chen Shi Juan , Ma Dan , Li Yan Wei
Published: February 2011

Amorphous nickel hydroxide powder codoped with Fe3+ and PO43- was synthesized by micro-emulsion precipitation method combined with rapid freezing technique. The microstructures of the prepared samples were characterized by XRD, SEM, EDS, and Raman spectra. The electrochemical performance of the prepared samples was analyzed by cyclic voltammetry, electrochemical impedance spectroscopy, and charge-discharge tests. The results showed that this amorphous nickel hydroxide codoped with Fe3+ and PO43- resulted in more structural defects within the nickel hydroxide. The Fe3+ and PO43- codoping could increase the specific discharge capacity and improve the electrochemical reversibility of the amorphous nickel hydroxide.
Novel Polyaspartic Ester Polyureas Based on Flexible Polyaspartic Ester
Authors: Lu Ping , Huang Wei Bo , Ma Xue Qiang , Liu Xu Dong
Published: February 2011

New polyaspartic ester (PAE) chain extender named PAE-f was prepared via two steps of Michael addition reactions:(1) Michael addition reaction between 4,4’-methylenebis(2-methyl cyclohexyl amine) (Laromin C260) and excessive dialkyl maleates（DEF）; (2) The Michael addition reaction of the residual dialkyl maleates of step (1) with polyester polyamine Jeffamine D230. The two-steps method proposed could reduce the reaction time in comparison with the current one step Michael addition reaction method, thus satisfying the industrialized production. New PAE based polyureas were synthesized by reacting the PAE-f chain extender with aliphatic polyisocyanates 4,4’-diisocyanato dicyclohexylmethane (H12MDI) / polyester polyamine Jeffamine D2000 prepolymer at room temperature. FT-IR and GPC were employed to characterize the new PAE prepared, and the morphology, molecular weight distribution and mechanical properties of the prepared PAE based polyureas were investigated by means of FT-IR and GPC. The FT-IR results indicated that the hydrogen bonding degree of amidogen groups in hard segments of the prepared polyureas were high, the length of hydrogen bonding were 0.305nm～0.306nm. The GPC experimental results show that the weight average molecular weight of the PAE-f based polyureas were 4.95×104～6.05×104,Mw/Mn were 1.65～1.97, the molecular weight distribution were relatively narrow. The mechanical properties demonstrated that the tensile strength were 14.7～22.5MPa, Elongation at break were 306～511%, Yang’s modulus were 67～127MPa, Shore A hardness were 64～83. The mechanical properties confirmed that the polyureas based on PAE-f were kinds of elastomeric materials with satisfied flexibility, strength, module and hardness.
Characterization and Properties of Cellulose Oleate
Authors: Huang Feng Yuan , Yu Yan , Wu Xiao Jie
Published: February 2011

Cellulose Oleate (CO) was synthesized by acylating cellulose in homogeneous system with p-toluenesulfonyl chloride (Tos-Cl) and oleic acid. The structure of CO was characterized by FT-IR, and degree of substitution (DS) of CO was determined by saponiﬁcation method. Substituent distribution analysis was carried out with curve-fitting method, and the results indicated that acyl reaction of cellulose with oleic acid preferred to react at primary hydroxyl groups. The CO converted into films by casting. The mechanical properties of CO films were investigated. With the increase of DS, the tensile strength decreases gradually, but the tensile strain increases apparently.
AC Impedance Spectroscopy Studies on Zn-Bi-Co-Mn-Ti System Low-Voltage Varistor Ceramics
Authors: Ju Jin Hua , Wang Hua , Xu Ji Wen , Yang Ling , Liu Si Jia , Di Jie Chang
Published: February 2011

The electrical responses of Zn-Bi-Co-Mn-Ti system low-voltage varistor ceramics were prepared by solid-state reaction method and were analyzed by AC impedance spectroscopy over a wide range of temperature (100~270°C) in the frequency range of 40~13MHz. The equivalent circuit adopts R (RQ)(RC) model. Imaginary part of impedance and modulus with frequency plot exhibits the varistor ceramics including resistance and capacitance. Impedance analysis enables us to separate the contributions from grains and grain boundaries of our samples. It indicates that grain boundary impedance is the main contributor for ceramic resistance, and grain boundary relaxation effects are most obvious in Zn-Bi-Co-Mn-Ti system. The AC grain boundary conductivity activation energy is attributed to the motion of oxygen vacancies within the bulk, and calculated by Arrhenius equation.
A New FEM for Torsion Cracked Cylinder Based on Crack3D FEA Code and Mushhelisvili Torsion Theorem
Authors: Tang Xin Yan
Published: February 2011

The objective of this paper is to use the specialty fracture software Crack3D FEA Code, well known Ansys software and Mushhelisvili’s torsion theorem to analyze the torsion problem of a crack rectangular cylinder. Several numerical results such as stress intensity factors KIII , torsion rigidity D, shearing stresses (τxy ,τyz ) and the contour nodal solution data are obtained. All the results are satisfactory.
Model and Imitation of the Cycle Temperature Fields and Deformations of Coke Drum
Authors: Chen Sun Yi
Published: February 2011

When the operating process of delay coking is cyclically changing from 25°C to 500°C, it would usually induce the effect of heat treatment on the shell of coke drum. After a special model of the kinetic medium climbing along the inside-wall of the coke drum at a steady rate set up, the resulting two-dimensional kinetic temperature field of shell in radial and axial directions has been calculated and analyzed by FEM. The relation between the material physical property of the shell and its temperature has been considered. The results show that the radial temperature difference or the axial temperature difference caused by the cooling water is more than that caused by the hot oil. The maximum temperature difference between the inside-wall and the outside-wall is 40°C below the medium level, 30mm by the hot oil and 60 °C or 25 mm by the cooling water. The circumferential uneven temperature field, location and concave/convex or incline/bend of body have been surveyed and analyzed. The lat-circle deformation of transverse section has been discussed.
Study on the Rice Straw Pretreated with NaOH for Biogasification
Authors: Li Jia You , Ye Xiao Mei , Yu Jian Xing , Cai Li Ling , Ruan Shan Ming , Chang Zhi Zhou
Published: February 2011

In this study, Box-Behnken design (BBD) and response surface analysis (RSA) methodology were employed to plan experiments and optimize the NaOH pretreatment of rice straw. Experimental results showed that concentration of NaOH (CS), treatment time (TT) and ratio of rice straw with NaOH (RS) were main factors governing the biogasification of rice straw. The polynomial equation describing the biogasification as a simultaneous function of the CS, TT and RS was confirmed. The FTIR analysis and SEM images of straws further confirmed that NaOH could disrupt the silicified waxy surface, break down the lignin-hemicellulose complex and partially remove silicon and lignin from the pretreated rice straw.
Short Crack Propagation Law and Fatigue Life Prediction Method for Structural Alloy Steel
Authors: Wang Zan Zhi
Published: February 2011

35CrMo and 42CrMo are the two main structural alloy steels in China, and are widely used in making important structural components subjected to heavy loads. In order to search after their fatigue properties under cyclic loads, 33 specimens were tested, under different stress level and different stress ratio from each other, to observe their crack initiation lives and the failure lives, together with the growing short crack lengths at various cycles. All tests were conducted using the MTS 810-22 material testing system. Based on the results from the tests, the relationships between the maximum stress range at crack tip and the number of cycles prior to crack initiation were determined, and in the meanwhile, the small crack propagation laws and the threshold stresses for fatigue crack initiation were obtained. In the end, the fatigue life prediction method for the two structural alloy steels was carried out.
Research on the Key Parameter of the Core Part on the Equipment for Peeling Off the Gingko’s Shell
Authors: Liu Shao Da , Zhu Li Xue
Published: February 2011

This paper takes decorticator's core part (Illustration of roller and shutter equipment) as the object of study, through analyzing the principle of the gingko decorticator for peeling off the shell, and choosing the roller's material and its superficial shape, we calculate the action of gingko’s entrance to the gap between roller and shutter, and elaborate the two influences on the effect of peeling off the shell, the gap between roller and shutter and the speed of peeling. The decorticator which makes through this research may achieve good results that the husking yield is bigger than 85%, percentages of damage is smaller than 10%, the broken kernel rate is smaller than 7%. And it provides the theory basis for the improvement design and use of the next generation installment for peeling the shell.
Threshold Stress Intensity Factor (Kth) in Inertial Effect Coefficient Model
Authors: Gu Li Xiong , Liu Zhi Fang , Xu Zhong Yong
Published: February 2011

In this paper we first review the inertial effect coefficient model for fatigue crak growth (FCG) under constant amplitude (CA) loading based on static fracture mechanics with thinking about the inertial effect coefficient and its impact to crack tip, and then discuss the relation between threshold stress intensity factor (Kth ) and fatigue crak growth rate, which is in good agreement with the result by analysing the relation between dynamical coefficient and fatigue crak growth rate. Comparison of the present analysis with experimental data taken from the literature demonstrates that threshold stress intensity factor (Kth) has a greater impact to the fatigue crack propagation.
Pulse Discharge Strengthening of 16Mn Welded Joint and Mechanical Performance
Authors: Fu Yu Ming , Chai Xuan , Zheng Li Juan , Li Hui
Published: February 2011

The way of pulse discharge strengthening is introduced, and the electromagnetic heat pulse discharge method can increase the strength and toughness of welded joints. 16Mn low alloy steel welded joints are used in the ZL-2 super pulse current generator, and the test of pulse discharge strengthening is carried out. And the mechanical performance comparison test of welded joint is finished. On the universal tensile machine, tensile strength test before and after strengthening has been done. On the S-4800 scanning electron microscope, micro-fracture morphology is analyzed. The results show that electromagnetic heat strengthening test is carried out based on the appropriate discharge parameters. In the junction of weld and base metal near the heat affected zone of the fracture, there is a white layer organization. It appears to improve the mechanical performance of welded joint, and enhance strength and toughness of welded joints.
Wear Mechanisms of PCBN Cutting Tools in Hard and Dry Cutting GCr15 Bearing Steel
Authors: Liu Rui Ping , Deng Fu Ming , Lu Xue Jun
Published: February 2011

GCr15 bearing steel was turned with PCBN cutting tools in a manner of hard and dry cutting, and the characteristics and morphology of rake and flank face of PCBN cutting tools were observed, the element distribution of different regions of rake and flank face of PCBN cutting tools were tested and analyzed by use of EDS, and finally the wear mechanisms of PCBN cutting tools were discussed. The results showed that the wear areas of rake and flank face of PCBN cutting tools were small and mostly concentrated near the tip and sub-chamfering, and the reason was mechanical, oxidation, chemical and phase transition wear, which resulted in the joint action of tool wear.
Investigation on Microstructure and Impact Properties of Borated Stainless Steel for High Density Storage Racks
Authors: Xue Fei , Luo Zhi Feng , Yu Wei Wei , Wang Zhao Xi , Zhang Lu
Published: February 2011

In this paper, microstructure and impact properties of borated stainless steel type 304B6-GradeB were investigated, which was used as raw materials of high-density storage racks in some nuclear power plants. Microscopic examinations reveal that a large amount of particles are heterogeneously distributed on austenitic matrix which displayed different shapes in the rolling and thickness directions, the results of XRD and EDS prove that the secondary particle is (Fe,Cr)2B and boron is distributed only in the particles while not in the matrix, fracture analysis all indicates that this borated stainless steel type 304B6-GradeB obviously exhibits features of brittle fracture.
Heat-Treated Microstructure and Mechanical Properties of TC4 Alloy
Authors: Dong Hong Bo , Yang Xin
Published: February 2011

The effects of heat treatment process on the microstructure and mechanical properties of TC4 alloy were investigated. The double shear and tensile tests were carried out by using the 12mm diameter standard specimens after solution treatment at 520°С for 1.5h and water quenching, followed by aging at 480-540°С for 8h. The microstructure and facture surface were analyzed using the equipment of metallurgical microscope and scanning electron microscopy. The results show that TC4 alloy show the best comprehensive performances after solution treatment at 940°С for 1.5h, aging at 520°С for 8h; the tensile specimens display a typical ductile fracture with oval dimples of various sizes; the microstructures with clear grain boundary and obvious lamellar structure are observed at room temperature. It indicates that the excellent comprehensive properties can be obtained by controlling the grain size of primary α phase and the morphology structure and amount of the secondary α phase at optimized aging temperature.
Dynamic Mechanical Behavior of Fiber Reinforced Polymer Composites Embedded with ZnO Whiskers
Authors: Zhou Wei , Wang Xi , Zhang Hong Bo , Rong Ji Li
Published: February 2011

Glass fiber reinforced polymer composites were prepared by dispersing zinc oxide (ZnO) whiskers in resin matrix. Static and dynamic tensile tests of the as-prepared composites were performed by means of a universal testing machine and the split hopkinson tensile bar (SHTB), respectively. Good tensile properties, which can be affected by the strain rates, of the composites are obtained. The fracture section morphology of the composites was investigated by scanning electron microscope (SEM). The different failure of the composites under static and dynamic tension is found. The tensile properties of the composites are dominated by pull-out and fracture of fiber bundles. The influence of ZnO whiskers on the performance of composites has been discussed. ZnO whiskers, which have unique three-dimensional structures and corresponding stress transfer, contribute to the tensile properties of the composites.
Study on Antioxidant Activity of Proanthocyanidins from Peanut Skin
Authors: Liu Zhi Qiang , Yang Qing Li , Zhang Chu Shu , Zhang Yan , Wang Shi Qing , Sun Jie
Published: February 2011

The research aimed to provide scientific basis for developing Proanthocyanidins from peanut skin. In this study, the antioxidant activity of Proanthocyanidins form peanut skin was studied at different system (O2-•, •OH and DPPH•) in vitro, with Vc. For O2-•, •OH and DPPH•, the IC50 of Proanthocyanidins form peanut skin was 0.143mg/mL, 0.097mg/mL and 0.274mg/mL; the IC50 of Vc was 0.163mg/mL, 0.097mg/mL and 0.306mg/mL. The result showed that proanthocyanidins from peanut skin had stronger antioxidant activity than Vc, and that Proanthocyanidins would be a effective natural free radical scavenger.
Fracture Analysis for Pitman Shaft of Automotive Steering Gear
Authors: Zhou Ze Jie , Wang Xiao Ming
Published: February 2011

The fractographic appearance, microstructure, chemical elements and hardness of the pitman shaft of automotive steering gear were analyzed. The fracture is induced by improper heat treatment and non-taking anti-carburization measures on thread part. Some feasible measures, including copperizing, coating anti-carburization paint and keeping localized manufacture allowance, were proposed for preventing the occurrence of similar fractures.
Interlaminar Shear Property of Z-Pins Reinforced Woven Ceramic Matrix Composites
Authors: Liu Wei , Jiao Gui Qiong , Zhang Wei Xi , Zhang Wei Min
Published: February 2011

Z-pins reinforced 2D ceramic matrix composites (CMCs), integratedly designed new materials, are developed to enhance 2D CMCs through-thickness in the form of Z-pins and to ensure significant increase in interlaminar fracture toughness, delamination resistance and impact resistance, and Z-pins reinforced 2D CMCs have much application. Finite element method was adopted to analyze stress distributions of Z-pins reinforced woven CMCs; the interlaminar shear tests were employed to measure interlaminar shear strength; fractographies were observed to examine failure mechanisms. The results are shown as the following: the insertion of Z-pins reduces concentrated stress fields and enhances the uniform stress distribution on the expected fracture plane. Interlaminar shear strength of Z-pins reinforced woven CMCs is increased as Z-pins insertion reaches a certain number. Interlaminar shear strength goes up with the rise of the number of inserted Z-pins. Z-pins shearing and fabric/matrix debonding are interlaminar failure mechanisms of Z-pins reinforced CMCs.
A Knitted Scaffold for Tendon Engineering Using Poly (Lactic Acid) Fibers
Authors: Guo Zheng , Chen Jin Jing , Zhang Pei Hua
Published: February 2011

A tubal knitted scaffold fabricated from poly(lactic acid) (PLA) yarns was given in this work. The performance of the scaffold during degradation in vitro and the morphology of the scaffold with cells (monkey dermal fibroblasts) were examined. The scaffold fabricated from poly(glycolic acid) (PGA) yarns was manufactured as the control. Results showed that the PLA scaffold could keep much more tensile strength during degradation in vitro, compared with the PGA scaffold. However, cell attachment and proliferation on the PGA scaffold were better than on the PLA scaffold.