bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite/Explicit Finite Element - Finite Difference Coupling Method for Analysis of Soil - Foundation System
Authors: Tang Hui , Li Xiao Jun , Zhou Guo Liang , Zhang Chun Ming
Published: November 2013

There are some coupling methods based on Finite Element Method and some other numerical methods, such as Infinite Element Method, Boundary Element Method, Finite Difference Method, etc. But these methods have their own limitations on simulation the foundation. For overcome these disadvantages, a coupling method is presented in this paper, which be proposed to analyze the effect of soil - foundation on seismic response of structures. In this coupling method, the structure and the surrounding soil are simulated with Finite Element method, and the other part of the soil with Explicit Finite Element - Finite Difference Method. Compared to other coupling methods, it is more flexible and its calculation amount is acceptable. The accuracy and effectiveness of the coupling method have been verified through Numerical experiment in this paper.
The Compaction Method of Backfill Site with Loess and the Tests of Soil Parameters
Authors: Zhu Yan Peng , Zhu Sheng Xiang , Ye Shuai Hua
Published: November 2013

To the question of reclaimed land of low hills, gentle slope and gully of Lanzhou City, including the compaction way of backfill site with loess and physical parameters of test, the paper discusses the main factors affecting the soil compaction, and put forward suitable compaction method of backfill site with loess. By analysing a large number of soil physical parameters experimental data, the paper gives empirical value to estimate the compaction coefficient and water content base on the quality of the sample or D-value of the quality. This article also discusses the relationship between the compaction curves and backfill ground on the same field or different. For the compaction of backfill site with loess and the parameters of the test in other city, it provides the reference.
Study on the Effect of Cellulose Fiber on the Crack Resistance of High Performance Concrete
Authors: Xiao Kai Tao , Yan Jian Jun , Peng Shang Shi
Published: November 2013

Combining the South-to-North Water Diversion Middle Route Project, the effect of cellulose fiber on the mechanical property, ultimate tensile value, compressive elasticity modulus, durability and crack resistance property of high performance concrete was studied. The test results show that mixing with the cellulose fiber in concrete has less effect on the compressive strength, but can improve the splitting tensile strength, the axial tensile strength and ultimate tensile value of concrete, extend the cracking time of concrete, reduce the crack width and the cracking area of concrete and improve the crack resistance of concrete.
Influence on CBR for Graded Crushed Rock on the Base of Port
Authors: Yuan Pu , Zhou Rui Bo , Dong Zhi Liang , Luo Yan
Published: November 2013

California bearing ratio (CBR) test was carried out, CBR changing laws of different graded crushed rocks were analyzed, an aggregate gradation on the base of port was put forward, and its performances were verified through laboratory test. Test result shows that the main skeleton structure composed of the aggregate with diameter 19mm-4.75 mm has interlocked force, and the optimal mass fraction is 90%~65%. The aggregates with diameter 4.75mm-0.075mm have the effects of filling the void of main skeleton structure, whose optimal mass fraction is 10%-35%.And the optimal mass fraction of the aggregate with diameter 19mm-9.5 mm is 25%.When the optimum proportion of coarse aggregate to middle aggregate is 25:40, the CBR value of coarse-middle-fine combined aggregate reaches the highest point, and is more than 158.97%, and the ratio reached 377%. On this basis, the optimal aggregate gradation of graded broken stone is reference on design and construction of graded crushed rock on the base of port.
Large Remanent Polarization of Pm2O3-Doped Bi4Ti3O12 Films
Authors: Chen Min , Mei X.A. , Huang C.Q.
Published: November 2013

Pm-doped bismuth titanate (Pm4-xLaxTi3O12: BPT) and pure Bi4Ti3O12(BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. For the samples with x=0.25, 1.0, and 1.25, the current-voltage characteristics exhibited negative differential resistance behaviors and their P-V hysteresis loops were characterized by large leakage current, whereas for the samples with x=0.5 and 0.75, the current-voltage characteristics showed simple ohmic behaviors and their P-V hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( Pr ) and coercive field (Ec) of the BPT Fims with x=0.75 were above 40μC/cm2 and 60KV/cm , respectively.
Fourier Transformation Infrared Spectrum Characteristics of Synthetic Zeolite A
Authors: Zhang Xiao Hu , Zhang Chun Ying , Zhan Feng , Chen Nan Chun
Published: November 2013

Synthesis of zeolite A by the use of natural materials (naturally stellerite) has been achieved without template agent. The final product was tested with X-ray diffraction, which was identified as the zeolite A. Then, the raw material and each step product were tested with Fourier Transformation Infrared (FT-IR). Comparing their FT-IR, we analyzed their spectrum characteristics, differences and reasons.
Preparation of Geopolymer Using Electrolytic Manganese Residue
Authors: Zhao Rong , Han Feng Lan
Published: November 2013

In this study, reference the method of preparing cement sand to produce geopolymer, using Electrolytic Manganese Residue(EMR), fly ash, magnesium slag (with boric acid), sodium silicate, sand, calcined kaolin as the main raw materials, focus on the study of using electrolytic manganese residue to produce Geopolymeric cement. Finally, through a series of comparison, we find out the best recipe of Geopolymer preparation, and the best ratio of each raw material is 80% EMR, 10% magnesium slag, 10% fly ash. In this way, the Geopolymer has the best mechanical properties.
Characterization of Layered Double Hydroxide Modified with Sodium Dodecyl Sulfate and its Dispersion in Polyethylene
Authors: Han Zhi Dong , Zhang Xin Ke , Wang Yue , Jiang Zheng Quan , Wang Peng
Published: November 2013

Mg-Al layered double hydroxide (LDH) was modified with sodium dodecyl sulfate (SDS) by regeneration method. The structure of modified LDH (SDS-LDH) was investigated by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The composites of SDS-LDH and polyethylene (PE) were prepared by melt blending and solution mixing method with maleated PE (PEgMA) as compatibilizer. The structure of the composites and the dispersion of SDS-LDH in the matrix were investigated by XRD and transmission electron microscopy (TEM), respectively. The results reveal that SDS was successfully intercalated into the interlayer space of LDH. SDS-LDH was hardly exfoliated in PE/PEgMA by melt blending. The nanocomposites of PE/(PEgMA/SDS-LDH) were successfully prepared by melt blending PE with SDS-LDH/PEgMA master-batch obtained by solution mixing. Homogeneous dispersion of SDS-LDH in the matrix was observed by TEM.
Evaluation of Impact Bending Strength of Ceramic Composites at Ultra-High Temperatures from 1500-2000 °C in Air
Authors: Wan De Tian , Bao Yi Wang , Zhao Hua , Tian Yuan
Published: November 2013

In this work, a new and novel test method was developed to determine the impact bending strength of ceramic composites at ultra-high temperature from 1500-2000 °C in air. Three-point impact bending test was carried out through a SiC pressure head with a dynamic force sensor fixed on a slider and movable along a guide rail. The impact load was adjusted by different saving energy and the impact speed was lower than 0.5 m/s. The center of the sample was heated up to about 1500-2000°C by oxygen-assisted spray combustion. An impact load was put on the specimen and the impact force was recorded automatically. The impact bending strength can be calculated from the maximal load and the sample size. To check the availability and reliability for this method, several ceramics including SiC, ZrB2/SiC and C/C fiber reinforced composite without coating, were used as the testing samples. The results indicate that this method is a good and feasible method for evaluating the mechanical properties of the ceramic composite at ultra-high temperatures.
Measuring Mechanical Properties of Zirconia Dental Crowns by Nanoindentation
Authors: Meng Zhao Qiang , Jiang Dan Yu
Published: November 2013

Mechanical properties of dental materials are increasingly studied via nanoindentation testing. Due to the excellent mechanical properties, 3-mol%-Yttria-Stabilized Tetragonal Zirconia (3Y-TZP) has become an attractive high-toughness core material for fixed dental restorations. In this paper, the mechanical properties of 3Y-TZP were studied by nanoindentation. The continuous stiffness measurement (CSM) and the single load/unload cycle test controlled by displacement and load respectively were performed with a Berkovich indenter.
The Effects of Load and Frequency on the Fatigue Damage of Bi-Layered Zirconia and Alumina Dental Composites
Authors: Liu Yi Hong , Zhu Lin Jia , Feng Hai Lan , Wang Yong , Zhang Qing Hui , Qiu Yan , Bao Yi Wang
Published: November 2013

It is significant to explore the fatigue contact damage of bi-layer ceramic composites in order to improve the long-time mechanical reliability of bi-layer structured dental restorations. In this study, Hertz contact test was used to compare the fracture modes and the ability of anti-fatigue damage of zirconia and alumina bi-layer composites, to analyze the effect of loading rate and other factors on the damage mechanisms of bi-layer ceramic composites. Cyclic spherical fatigue loading was put on the bi-layer alumina and zirconia composites with different substrates. The samples were observed by high depth of field stereomicroscope and digital optical microscope after test. The results showed that the fatigue contact damage mode of zirconia bi-layer composite was the porcelain fracture from radial cracks without the damage of zirconia core. The fatigue contact damage mode of alumina bi-layer composite was the alumina core failure from radial cracks as the function of contact load. For both of zirconia and alumina bi-layer samples, the number of cycles to the sample failure as the function of same maximum contact load with high loading rate was obviously smaller than low loading rate. The mechanical properties of the substrate materials had limited effects on the number of cycles to the failure of both zirconia and alumina bi-layer samples from contact-induced radial cracks as maximum contact load with low loading rate. The ability of the zirconia bi-layer composites to resist fatigue damage was much higher than that of the alumina bi-layer composites.
Microstructure and Chemical Composition of Boron Nitride Fibers
Authors: Li Ru , Li Chuan Shan , Tang Jie , Tang Jian Xin , Du Xiao Yong , Zhang Ming Xia , Wang Chong Hai , Zhou Chang Ling
Published: November 2013

Boron nitride(BN) fibres were synthesized by modified technique of Economy’s method. The products were characterized by X-ray diffraction (XRD), fourier transform infrared (FT-IR) absorption spectroscopy, field-emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectrum (EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that BN fibers were mainly hexagonal boron nitride (h-BN) with diameters of 5-8 μm and the major compositions of BN fibers are B and N with a very small amount of O and C. At last, the chemical composition of samples were determined by the chemical analysis test method like GB/T 16555-2008 and GJB 507-1998.
Oxidation Behavior of Pressureless Liquid Phase Sintered SiC
Authors: Chen Yu Hong , Jiang Liang , Sun Wen Zhou , Wu Lan Er
Published: November 2013

The present study aims to investigate the oxidation behavioue of pressuerless sintered SiC ceramic with the AlN-Y2O3as sintering additives. Two main aspects are considered: The evaluation of oxidation kinetics in the temperature rang 1200°C-1400°C for short term test (30hr) and the degradation of the flexural strength after oxidation at temperature 1400°C for 100hr. The microstructure of surface oxidation layer of silicon carbide at high temperature is studied, and the effect of reactive product s on the high temperature oxidation resistance is also analyzed. The results showed that the oxidation began at temperature more than 1200°C, and the oxidation kinetics is obeyed parabolic rule. After long term oxidation, the fracture strength decreased greatly.Key words: oxidation behavior, liquid phase sintering, silicon carbide
Impact of CrAlN Coatings on Oxidation Behavior of K38G Alloy at 800 and 900°C
Authors: Zhang Hao , Duo Shu Wang , Xu Xiang Min , Luo Fei Fei , Ke Huan , Liu Ting Zhi , Chang Yu Chuan
Published: November 2013

CrAlN coatings have been deposited on K38G alloy by Closed Filed Unbalanced Magnetron Sputter Ion Plating (CFUMSIP). The microstructure, surface and section morphology of CrAlN coatings before and after oxidation were analyzed by XRD and SEM. At the same time, the mechanical properties and oxidation resistance of CrAlN coating were also studied. The results indicate that the phases in the isometric crystal CrAlN coatings with a hardness of 3500 HV and a adhension of 20 N was the coexistence of CrN and AlN. Each element of CrAlN coatings still existed at 800 and 900°C, but it demonstrated better high-temperature oxidation resistance because of denser oxide scale at 800°C. Besides, internal oxidation occurred under the two temperatures.
Mechanical Properties and Oxidation Resistance of CrN Coatings Deposited by Closed Field Unbalanced Magnetron Sputter Ion Plating
Authors: Zhang Hao , Duo Shu Wang , Xu Xiang Min , Luo Fei Fei , Liu Ting Zhi , Zhou Zi Hao
Published: November 2013

CrN coatings were prepared by Closed Filed Unbalanced Magnetron Sputter Ion Plating (CFUMSIP). The microstructure and morphologies of CrN coatings before and after oxidation were analyzed by XRD and SEM. At the same time, the mechanical properties and oxidation resistance of CrN coating were also studied. The results indicate that the phase in the dense CrN coatings with a hardness of 1979 HV and a adhension of 54 N was the coexistence of Cr, Cr2N and CrN. Besides, The CrN coatings showed good high-temperature oxidation resistance at 700°C while the coating failed at 800°C.
Electrical Characterization and Microstructures of Ce-Doped Bi4Ti3O12 Thin Films
Authors: Mei X.A. , Chen Min , Liu J. , Liu R.F.
Published: November 2013

Ce-doped bismuth titanate (Bi4-xCexTi3O12: BCT) and pure Bi4Ti3O12 (BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by pulsed laser deposition technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. The experimental results indicated that Ce doping into BIT result in a remarkable improvement in ferroelectric propertis. The Pr and the Ec values of the BCT film with x=0.75 were 23 μC/cm2 and 80 kV/cm, respectively.
Electrical Characterization and Microstructures of Y2O3-Doped Bi4Ti3O12 Thin Films
Authors: Chen Min , Liu J. , Mei X.A.
Published: November 2013

Y2O3-doped bismuth titanate (Bi4-xYxTi3O12: BYT) and pure Bi4Ti3O12 (BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. Y-doping into BIT caused a large shift of the Curie temperature ( TC ) from 675 °C to lower temperature and a improvement in dielectric property. The experimental results indicated that Y doping into BIT also result in a remarkable improvement in ferroelectric property. The Pr and the Ec values of the BYT film with x=0.75 were 28 μC/cm2 and 65 kV/cm, respectively.
Ferroelectric Properties of Bi4-xYbxTi3O12 Thin Films
Authors: Huang Chong Qing , Mei X.A. , Chen M. , Liu J.
Published: November 2013

Yb-doped bismuth titanate and random oriented Bi4-xYbxTi3O12 (BYbT) thin films were fabricated on Pt/Ti/SiO2/Si substrate with pulsed laser deposition method. The structures and ferroelectric properties of the BYbT films were investigated. Yb doping resulted in a marked improvement in remanent polarization (Pr) and coercive field (Ec). At an applied electric field of 120kV/cm, the Pr and (Ec) of the BYbT (x=0.8) films annealed at 650°C were 20 μC/cm2 and 85 KV/cm, respectively.
Ferroelectric Properties of Bi4-xPmxTi3O12 Ceramics
Authors: Tian Fang , Mei X.A. , Chen M. , Huang C.Q.
Published: November 2013

The electrical properties of Pm2O3-doped bismuth titanate,Bi4-xPmxTi3O12 (BPT) ceramics prepared by a conventional electroceramic technique were investigated. XRD analyses revealed Bi-layered perovskite structure in all samples. SEM micrographs showed randomly oriented and plate-like morphology. For the samples with x=0.4 and 1.0 P-E hysteresis loops were characterized by large leakage current, whereas for the samples with x=0.6 and 0.8 P-E hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( Pr ) and coercive field (Ec) of the BPT ceramic with x=0.8 were above 18μC/cm2 and 75KV/cm , respectively.
Advancement in Ferrite-Based Alloy Coatings by Laser Cladding
Authors: Yu Hui Jun , He Ting , Chen Chuan Zhong
Published: November 2013

Fe-based alloy is widely used for its good wear resistance and high performance-to-price ratio compared with other alloys. Laser cladding is a kind of valid method of metal surface modification, which has been successfully employed to modify the microstructure and/or composition of the near surface region to improve the wear, corrosion and oxidation resistance of a ferrite-based alloy component. In this paper, the recent research status in laser clad ferrite-based alloys is reviewed. The rules of designing laser cladding materials are introduced. The main problems and the solutions of the laser cladding materials application are analysized. The development tendency of laser cladding is forecast.
Effect of Er3+ Doped on Photocatalytic Properties of ZnO-TiO2 Nanofibers
Authors: Wang Meng , Fang Ming Hao , Tang Chao , Huang Zhao Hui , Liu Yang Ai , Wu Xiao Wen
Published: November 2013

Er3+ doped ZnO-TiO2 nanofibers with diameter of 100～200 nm were prepared by electrospinning mothed after calcined at high temperature, using polyvinylpyrrolidone(PVP), Zn(NO3)2·6H2O, Er(NO3)3·5H2O, Ti(OC4H9)4 asraw materials. The composite nanofibers were characterized by XRD, SEM, and UV-V respectively. Effects of different calcined temperatures on structure and photocatalytic degradation were investigated. The results indicated that the crystallinity becomes better with the increasing of calcination temperature. The composite nanofibers had the best effects of photocatalytic degradation of methylene blue, when Er3+ doping content was 0.3 wt.% and calcined temperature was 500 °C.
Influence of MnO2 on Properties of ZrO2-Al2O3-SiO2 Infrared Radiation Materials
Authors: Fang Ming Hao , Min Xin , Wang Fan , Huang Zhao Hui , Liu Yang Ai , Wu Xiao Wen , Tang Chao
Published: November 2013

In this paper, the effect of MnO2 addition the infrared emissivity on ZrO2-Al2O3-SiO2 low thermal conductivity materials was investigated. The phase and microscopic morphology of the samples with the heat treatment at different temperatures were characterized by XRD and SEM. The results show that the infrared emissivity of ZrO2-Al2O3-SiO2 materials increased nearly 7% to 0.911 by adding 10 wt% MnO2. After heat treatment at different temperature, the main phase of ZrO2-Al2O3-SiO2 materials were t-ZrO2 and mullite, ZrO2-Al2O3-SiO2 materials with MnO2 addition were molten and the phase composition was t-ZrO2, Al2O3, and m-ZrO2.
Test of Relative Translucency of 5 All-Ceramic Core Materials
Authors: Chen Jian Feng , Dang Rui Jie , Zhao Li Sheng , Deng Bin , Gu Bin , Wen Ning
Published: November 2013

Objective:To study the relative translucency of 5 veneered and glazed all-ceramic systems core material, including Procerra AllCeram Alumina, Vita In-Ceram Zirconium, Ivoclar Vivodent Empress, In-Ceram Spinell and Colored Zirconia. Methods: Under standard black and white background, the surface light reflectivity of 5 veneered all-ceramic systems core material was determined with contact color difference meter, and the ratio of Yb /Yw was calculated. Results: After veneered, the relative translucency of 5 core materials all declined, and ranged from 0.6740 of In-Ceram Spinell to 1.00 of In-Ceram zirconia, among of that In-Ceram Spinell was most transparent. Conclusion: Among the groups, there is no significant differences among Empress II, Procera AllCeram and Colored Zirconia (IL1,IL2,IL3). Compared with Procera AllCeram and Vita In-Ceram Zirconium , Procera AllCeram has significant difference. There is a significant difference between Procera AllCeram and In-Ceram Spinell.
Effect of Temperature on Structural and Optical Properties of ZnO Nanorods by Hydrothermal Method
Authors: Fei Xiao Yan , Luo Jun , Duo Shu Wang , Zhang Hao , Xu Xiang Min , Liu Ting Zhi
Published: November 2013

The ZnO nanorods were prepared at 130 °C, 160 °C and 190 °C for 6 h by hydrothermal method. The structural and optical properties of ZnO nanorods were invesitigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). XRD pattern analysis showed that the ZnO nanorods are the hexagonal structure (space group P63 mc). No other crystal phases, such as Zn and Zn (OH)2 were detected. FT-IR study identified the sharp peak that appeared at 573 cm-1 is related with the ZnO stretching mode. Also, SEM images revealed that the diameter of a single ZnO crystal ranges from 100 to 300 nm and the length ranges from 1 to 3 μm.
Preparation and Property of Reduced Graphene for Hummers
Authors: Jiang Yan Li , Tian Mei , Yu Ying Hui , Liu Jia Yao , Liu Shuang
Published: November 2013

Graphene material has ideal lattice structure and unique electrical, optical and other properties. In the electronics, composite materials, and other fields it has a broad application prospect. In this paper, using the Hummers method, to prepare oxidized graphite and graphene , to optimize the conditions of the preparation of graphite oxide. With two kinds of reductors, glucose and hydrazine hydrate, reduction graphite oxide, and dropped silver ions in the process of reduction. Using XRD, SEM and Raman spectra to character and analyze the products. The result showed that the graphite and silver ions in the oxidation reaction process were both restored by glucose, hydrazine hydrate. This structure that silver nanoparticles are uniformly distributed in the graphene sheet layers, can effectively prevent the reunion of graphene layers, and also upset the rules of the pile of the graphene layers.
Pore Structure and Microstructure of Super Light-Weight Foam Concrete Reinforced by Inorganic Fiber
Authors: Yu Xin Gang , Wu Di , Hao Hao , Zhang Yi , Xu Hong Chao , Rui Ya Nian
Published: November 2013

Super light-weight foam concrete with the density less than 250Kg/m3 was prepared by the physical foaming method. The pore structure and microstructure of the super light-weight foam concrete was analyzed by scanning electron microscopy.
Effect of WO3 Doping on Microstructural and Electrical Properties of ZnO-Pr6O11 Based Varistor Materials
Authors: Fu Xiu Li , Zang Yan Xu , Peng Zhi Jian
Published: November 2013

The effect of WO3doping on microstructural and electrical properties of ZnO-Pr6O11based varistor materials was investigated. The doped WO3plays a role of inhibitor in ZnO grain growth, resulting in decreased average grain size from 2.68 to 1.68 μm with increasing doping level of WO3from 0 to 0.5 mol%. When the doping level of WO3was lower than 0.05 mol%, the nonlinear current-voltage characteristics of the obtained varistors could be improved significantly with increasing amount of WO3doped. But when the doping level of WO3became higher, their nonlinear current-voltage performance would be dramatically deteriorated when more WO3was doped. The optimum nonlinear coefficient, varistor voltage, and leakage current of the samples were about 13.71, 710 V/mm and 13 μA/cm2, respectively, when the doping level of WO3was in the range from 0.03 to 0.05 mol%.
Preparation and Characterization of ZrO2 Coating by Sol-Gel on Mullite Short Fiber
Authors: Zhao Ying Na , Zhang Meng , Ren Jiang , Zeng Xiong Feng
Published: November 2013

The modified mullite fiber was used to toughen the mullite ceramic, which can effectively overcome the brittleness of ceramic materials and improve the material strength and toughness. Using 8ZrOCl2•H2O as precursor, anhydrous ethanol as solvent, H2O2 as hydrolysis promoter and NH3·H2O as precipitant, the stable and transparent zirconium sol could be obtained by sol-gel process, which coated mullite short fiber. The results showed that the stable and transparent ZrO2 sol was obtained when pH value was 3.8~4.8 and reaction temperature was at 25°C. XRD results indicated that monoclinic ZrO2 particles grew up and formed after heat-treatment at 700°C. The coating ZrO2 film combined with mullite fiber homogeneously and closely, and the film thickness was about 1 μm.
Low Sintering Temperature for Li-, Sb-, and Ta- Modified (K,Na)NbO3-Based Ceramics from Nanopowders
Authors: Zhang Hui , Wang Xiao Hui , Fang Jian , Shen Zheng Bo
Published: November 2013

In this paper, (Na0.52K0.44Li0.04)(Nb0.86Ta0.06Sb0.08)O3 (LTS-KNN) ultrafine-grained ceramic were fabricated over a low and wide temperature range, by using the nanopowder prepared from a water-based sol-gel method. nanopowders are demonstrated to be suitable for preparing fine-grained potassium-sodium niobate ceramics with desirable properties.
Spark Plasma Sintered WC-Ni Cemented Carbides with Various Contents of ZrC Nano-Powder
Authors: Ren Xiao Yong , Peng Zhi Jian , Peng Ying , Wang Cheng Biao , Fu Zhi Qiang , Qi Long Hao , Miao He Zhuo
Published: November 2013

WC-10Ni cemented carbides with various contents (0-9 wt.%) of ZrC nanopowder were fabricated by spark plasma sintering at 1350 °C with a pressure of 50 MPa. The phase composition, microstructure and mechanical properties of the as-prepared samples were investigated. X-ray diffraction analysis revealed that excepting WC hard phase, a solid solution phase Ni (W,Zr) with different amounts of individual metal was formed with increasing ZrC nanopowder content. Scanning electron microscopy examination indicated that a proper addition content of ZrC can suppress the abnormal growth of WC grains and improve the relative density of WC-Ni cemented carbides. However, with further increase in the content of ZrC (more than 7 wt.%), the agglomeration of ZrC became more and more serious. The samples with 5 wt.% ZrC nanopowder possess a relative higher flexural strength (~1750 MPa) among all the investigated samples. When the addition content of ZrC nanopowder was 3 wt.%, the Vickers hardness of the samples reached its maximum value (~1810 HV10).
Raman Spectroscopy Study of YSZ Co-Doped with CeO2/Gd2O3
Authors: Xie Xiao Hu , Liu Kai Qi , Yang Fen Rong , Ding Yu
Published: November 2013

Phase characterization is critical in material properties probing. In this study, Raman scattering was employed to identify the phase of YSZ co-doped with CeO2/Gd2O3. As a comparing, XRD for co-doped YSZ was also measured. The results show that introducing a small amount of CeO2/Gd2O3 into YSZ can lead to a change on Raman spectroscopy. Raman peaks appear with co-doping is attributed to the local structure change which caused by the re-distribution of vacancy. Comparing to XRD, Raman spectroscopy shows a more sensitive on the phase identify for the YSZ with a small amount dopant.
Effect of N2 Flow Rate on Structure and Mechanical Properties of CrN Coatings Prepared by Closed Field Unbalanced Magnetron Sputtering
Authors: Zhang Hao , Duo Shu Wang , Xu Xiang Min , Liu Ting Zhi
Published: November 2013

CrN coatings were deposited by Closed Filed Unbalanced Magnetron Sputtering (CFUMS). The effect of N2 flow rate on composition, phase components, morphologies and mechanical properties of CrN coatings were studied. The results show that the deposition rate of CrN coatings declined with the increase of nitrogen flow percentage in a Ar/N2 mixture atmosphere. When the nitrogen flow percentage reached 50% or more, the Cr and N atomic ratio of CrN coatings is close to 1:1. The phase in coatings was the coexistence of Cr, Cr2N and CrN, but the crystal preferred orientation changed significantly with the different N2 flow rates. The columnar crystal CrN coating with low N2 flow rate was denser. The hardness and adhension of CrN coatings have no direct relationship with N2 flow rate.
Pelvic posterior compartment defects: comparative study of two vaginal surgical procedures
Authors: Leanza Vito , Intagliata Eva , Leanza Gianluca , Vecchio Rosario
Published: November 2013

This study was undertaken to compare two surgical techniques for rectocele repair. Between January 2005 and December 2010, 180 patients with III grade symptomatic rectocele were enrolled in this alternative prospective randomized study. 90 patients (group A) were treated with perineal body anchorage of posterior septum, and 90 (group B) with the traditional Denonvilliers’ transversal suture. Pre- and post-operative data, including Ap and Bp values, recurrence rates and quality of life was assessed. The mean follow-up was 22 months (range 9-72 months). For statistical purpose, Student’s t test, chi-square test and logistic regression analysis were evaluated. Post-operatively, in group A Ap and Bp value were respectively –2.0±1.0 and –2.5±0.5 (P<0.001 for both values). In group B, Ap and Bp value were respectively –1.9±2.1 and –2.1±0.9 (P<0.001 for both values). A total of 81 (93.1%) patients in group A and 76 (86.3%) in group B reported improvement in symptoms (P=0.222) after surgery. Recurrence rates were 5 (5.7%) and 6 (6.8%) respectively (P=0.984). Quality of life improved significantly in both groups. In conclusion, both techniques are effective for the posterior compartment repair.
James Alfred Loader: ’n Huldeblyk aan ’n krities-solidêre profeet in die eties-teologiese tradisie/James Alfred Loader: A tribute to a critical-solidary prophet in the ethical theological tradition
Authors: Van Aarde Andries G. , Dreyer Yolanda
Published: November 2013

This article is the introduction to the James Alfred Loader Dedication. It consists of a tribute to Professor Loader’s academic contribution to Old Testament, Middle-Eastern religio-literary studies and the Rabbinical background of the Old- and New Testament. The article is modelled after the tribute published in German in the annual publication of the Evangelisch-Theologische Fakultät Wien (Vienna, Austria) due to the honorary doctorate conferred on Professor Loader by the University of Pretoria (South Africa) in 2009. The tribute is combined with a comprehensive curriculum vitae, in part written in German, Afrikaans and English, and consisting of referencing Professor Loader’s personal data, his role as minister of religion, his academic awards, participation in scholarly societies, professional academic positions, academic reviewing, editorial activity, presentation of academic papers and a list of publications.
Mats of the nonnative macroalga, Gracilaria vermiculophylla, alter net denitrification rates and nutrient fluxes on intertidal mudflats
Authors: Gonzalez Dana J. , Smyth Ashley R. , Piehler Michael F. , McGlathery Karen J.
Published: November 2013

We hypothesized that mats of a nonnative macroalga, Gracilaria vermiculophylla, which is often found incorporated several centimeters into intertidal mudflat sediments, would increase net denitrification rates relative to bare sediments. At moderate densities (∼ 40 g dry weight [dry wt] m−2), net denitrification rates in June (182.37 ± 16.87 µmol N‐N2 m−2 h−1), July (213.19 ± 16.30 µmol N‐N2 m−2 h−1), and September (124.82 ± 11.17 µmol N‐N2 m−2 h−1) were higher than rates previously documented with macroalgal mats. Compared with rates from bare sediment in June (25.48 ± 15.09 µmol N‐N2 m−2 h−1) and September (46.47 ± 15.79 µmol N‐N2 m−2 h−1), net denitrification was significantly higher when G. vermiculophylla was present. Rates measured on bare sediment in July (254.81 ± 19.86 µmol N‐N2 m−2 h−1) were not significantly different from G. vermiculophylla counterparts, most likely because of highly reduced conditions in G. vermiculophylla cores, which could have limited nitrification. July incubations also demonstrate that at higher densities (∼ 120 g dry wt m−2 G. vermiculophylla), denitrification rates can drop, suggesting a potential biomass threshold for macroalgal enhancement of denitrification.
Disturbance and productivity as codeterminants of stream food web complexity in the Arctic
Authors: Parker Stephanie M. , Huryn Alexander D.
Published: November 2013

Disturbance and productivity are potentially interacting factors often thought to underlie the complexity of aquatic food webs. We tested predictions about the effects of disturbance (bed movement, total water column freezing) and productivity (as indicated by primary consumer biomass) on the structure of 19 stream food webs in arctic Alaska. We predicted that food webs subject to high levels of disturbance would have low connectance, low linkage density, and short food chains, while food webs of streams with more benign disturbance regimes would be more complex (i.e., a test of the “dynamic stability hypothesis”). We further predicted that food chain length would increase with productivity (i.e., testing the “resource‐availability hypothesis”). Connectance and linkage density were negatively related to bed movement but not to freezing. Food chain length was related to freezing but not to bed movement or productivity. The relationships among food chain length, freezing, and productivity were driven by the occurrence of fishless streams, which all froze during winter. Streams containing fish had longer food chains than fishless streams, and food chain length was positively related to productivity only when fishless streams were removed from analyses. Our results show that disturbance and productivity are codeterminants of stream food web complexity in the Arctic. Our data further suggest that colonization dynamics are an important factor controlling food web structure, highlighting the importance of idiosyncratic habitat and life history related factors that are often overlooked in theoretical studies.
Green algae blooms caused by Ulva prolifera in the southern Yellow Sea: Identification of the original bloom location and evaluation of biological processes occurring during the early northward floating period
Authors: Huo Yuanzi , Zhang Jianheng , Chen Liping , Hu Ming , Yu Kefeng , Chen Qunfang , He Qing , He Peimin
Published: November 2013

Over the past 6 yr, green algae blooms mainly caused by Ulva prolifera have been recorded in the Yellow Sea. Although satellite images provide a clear picture of the formation of these macroalgal blooms, the location of the original bloom area and the biological processes that occur during the early northward floating period remain poorly understood. Results obtained from more than 50 cruises conducted along coastal areas of the southwest Yellow Sea showed that the blooms originated along the coast of the Rudong area, where oceanographic conditions were favorable for accumulation of floating green algae. The dominant Ulva species changed during the period of northward drift. Massive floating Ulva blooms dominated by U. prolifera occurred mainly from June until the bloom disappeared. U. prolifera dominated the assemblage due to its rapid growth and production under suitable environmental conditions and its apparent competitive advantages over other Ulva species. Phylogenetic analysis of 5S spacer sequences showed that U. prolifera blooms in the Yellow Sea were not from a single genetic source and likely originated from or were supplemented with a number of different genetic sources.
Using timescales to interpret dissolved oxygen distributions in the bottom waters of Chesapeake Bay
Authors: Shen Jian , Hong Bo , Kuo Albert Y.
Published: November 2013

A simplified conceptual model based on timescales of gravitational circulation, vertical exchange, and total oxygen consumption rate of the biochemical processes is presented to provide insight into the relationships between estuarine dynamics and bottom water dissolved oxygen (DO). Two dimensionless parameters are introduced to diagnose the relationship between the vertical exchange process and the biochemical DO consumption and the influence of gravitational circulation on replenishment of bottom DO. The relative magnitudes of these timescales provide a linkage between the physical and biochemical processes. The hypoxic and anoxic conditions in deep waters of Chesapeake Bay are successfully interpreted with these three proposed timescales. Because the Bay is a long estuary, the replenishment of the bottom DO due to gravitational circulation diminishes as the bottom water travels farther upstream. The bottom DO is mainly modulated by the vertical exchange process in the middle and upper portions of the Bay. In addition to other physical processes that affect vertical exchange, wind and freshwater are the major predictors of the vertical exchange time. The model is applicable to Chesapeake Bay and other estuaries with persistent gravitational circulation if the dimensionless parameters can be appropriately estimated.
Chemical diversity and spatial variability in myriad lakes in Nhecolândia in the Pantanal wetlands of Brazil
Authors: Furian Sônia , Martins Elisângela Rosemeri Curti , Parizotto Tatiana Mascari , Rezende-Filho Ary Tavares , Victoria Reynaldo Luiz , Barbiero Laurent
Published: November 2013

Nearly 15,000 shallow, saline or freshwater lakes and ponds coexist in close proximity in the Nhecolândia, a 24,000 km2 subregion of the Pantanal wetland in Brazil. This study aims to understand the origin of such diversity in surface water, which is a key aspect for the wetland services and biodiversity in the region. Both soil observations and water samples were collected at the regional or local scale and supplemented by previously published data sets. Statistical and geostatistical treatments were carried out and completed by discrete water‐table monitoring. The results confirmed the absence of a regional pattern in surface‐water salinity, and the independence of electrical conductivity values, even for neighboring lakes. Despite great differences in chemical composition, all surface waters in the region belong to the same chemical family, corresponding to several concentration stages of the Taquari River water that supplies the region. The concentration stage depends on the hydrological functioning of each lake, which is itself controlled by the relative importance of low‐permeability soils as a barrier to movement of water into or out of the lakes through the subsurface. In this framework, oligosaline ponds, freshwater lakes, and saline lakes work as recharge, flow‐through, and discharge wetlands, respectively. The salinity observed in some lakes results from an ongoing process of accumulation and evaporation under relatively humid climatic conditions and poor drainage.
Seasonal and interannual variation in the extent of hypoxia in the northern California Current from 1998–2012
Authors: Peterson Jay O. , Morgan Cheryl A. , Peterson William T. , Lorenzo Emanuele Di
Published: November 2013

This study addresses the occurrence, severity, and extent of hypoxia over the continental shelf of the northern California Current (40–48.5°N latitude) from 1998 to 2012. Clear seasonal trends exist in the timing and duration of hypoxia. The highest bottom‐water dissolved oxygen concentrations occurred from November to March, and levels below the 1.4 mL L−1 hypoxia threshold were detected during the upwelling season (May through October). Regions of hypoxia tended to occur north of 42°N latitude and were most severe over the widest areas of the continental shelf. Hypoxic waters covered up to 62% (15,600 km2) of the continental shelf during some years (2002, 2007, 2008), and < 10% in others (2003, 2010–2011). There are seasonal and interannual shifts in both the depth and oxygen content of upwelled waters. Years with the greatest extent and severity of hypoxia had the lowest concentration of dissolved oxygen in upwelling source waters. The dissolved oxygen concentration of source waters showed a gradual decline from 1998 through 2007, with a subsequent increase from 2008–2010 before leveling off in 2011 and 2012. The variability in oxygen content of source waters correlates well with the North Pacific Gyre Oscillation and may indicate the importance of large‐scale climate dynamics in determining the extent and severity of hypoxia in the northern California Current.
In situ submicron organic aerosol characterization at a boreal forest research station during HUMPPA-COPEC 2010 using soft and hard ionization mass spectrometry
Authors: Vogel A. L. , Äijälä M. , Corrigan A. L. , Junninen H. , Ehn M. , Petäjä T. , Worsnop D. R. , Kulmala M. , Russell L. M. , Williams J. , Hoffmann T.
Published: November 2013

Abstract. The chemical composition of submicron aerosol during the comprehensive field campaign HUMPPA-COPEC 2010 at Hyytiälä, Finland, is presented. The focus lies on online measurements of organic acids, which were achieved by using atmospheric pressure chemical ionization (APCI) ion trap mass spectrometry (IT-MS). These measurements were accompanied by aerosol mass spectrometry (AMS) measurements and Fourier transform infrared spectroscopy (FTIR) of filter samples, all showing a high degree of correlation. The soft ionization mass spectrometer alternated between gas-phase measurements solely and measuring the sum of gas and particle phase. The AMS measurements of C, H and O elemental composition show that the aerosol during the campaign was highly oxidized, which appears reasonable due to high and prolonged radiation during the boreal summer measurement period as well as the long transport times of some of the aerosol. In order to contrast ambient and laboratory aerosol, an average organic acid pattern, measured by APCI-IT-MS during the campaign, was compared to terpene ozonolysis products in a laboratory reaction chamber. Identification of single organic acid species remains a major challenge due to the complexity of the boreal forest aerosol. Unambiguous online species identification was attempted by the combinatorial approach of identifying unique fragments in the MS2 mode of standards, and then comparing these results with MS2 field spectra. During the campaign, unique fragments of limonene-derived organic acids (limonic acid and ketolimononic acid) and of the biomass burning tracer vanillic acid were detected. Other specific fragments (neutral loss of 28 Da) in the MS2 suggest the occurrence of semialdehydes. Furthermore, an approach to determine the average molecular weight of the aerosol is presented. The campaign average organic molecular weight was determined to be 300 g mol−1. However, a plume of aged biomass burning aerosol, arriving at Hyytiälä from Russia, contained organic compounds up to 800 Da (MWom≈450 g mol−1), showing that the average molecular weight can vary significantly. The high measurement frequency of both AMS and APCI-IT-MS enabled the partitioning of selected organic acids between gas and particle phase as a function of the total particulate mass to be quantified. Surprisingly high fractions of the higher molecular weight organic acids were observed to reside in the gas phase. These observations might be a consequence of large equilibration timescales for semi-solid boreal forest aerosol, as has been recently hypothesized by Shiraiwa and Seinfeld (2012).
Variations of oxygen-18 in West Siberian precipitation during the last 50 yr
Authors: Butzin M. , Werner M. , Masson-Delmotte V. , Risi C. , Frankenberg C. , Gribanov K. , Jouzel J. , Zakharov V. I.
Published: November 2013

Abstract. Global warming is associated with large increase in surface air temperature and precipitation in Siberia. Here, we apply the isotope-enhanced atmospheric general circulation model ECHAM5-wiso to investigate the variability of δ18O in West Siberian precipitation and the underlying mechanisms during the last fifty years, and to assess the potential of a recently opened monitoring station in Kourovka (57.04° N, 59.55° E) to successfully track large-scale water cycle and climate change in this area. Our model is constrained to atmospheric reanalysis fields to facilitate the comparison with precipitation δ18O from observations. In Russia, annual-mean model surface temperatures agree within ±1.5 °C with climatological data, while the model tends to overestimate precipitation by 10–20 mm month−1. Simulated precipitation δ18O shows a southwest to northeast decreasing pattern. The simulated annual-mean and seasonal δ18O results are in overall good agreement with observations from 15 Russian stations of the Global Network of Isotopes in Precipitation between 1970 and 2009. Annual-mean model results and measurements are highly correlated (r2~0.95) with a root mean square deviation of ±1‰. The model reproduces the seasonal variability of δ18O, which parallels the seasonal cycle of temperature, and the seasonal range from −25‰ in winter to −5‰ in summer. Analysing model results for the extended period 1960–2010, long-term increasing trends in temperature, precipitation and δ18O are detected in western Siberia. During the last 50 yr, winter temperatures have increased by 1.8 °C. Annual-mean precipitation rates have increased by 2–6 mm month−1 50 yr−1. Long-term trends of precipitation δ18O are also positive but at the detection limit (<1‰ 50 yr−1). Regional climate is characterized by strong interannual variability, which in winter is strongly related to the North Atlantic Oscillation. In ECHAM5-wiso, regional temperature is the predominant factor controlling δ18O variations on interannual to decadal time scales with slopes of about 0.5‰ °C−1. Focusing on Kourovka, the simulated evolution of temperature, δ18O and, to a smaller extent, precipitation during the last fifty years is synchronous with model results averaged over entire western Siberia, suggesting that this site will be representative to monitor future isotopic changes this region.