bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Dislocation Density on Micromechanical Characteristics of Cu6Sn5 and Cu3Sn
Authors: Wang Yi Kai , Liu Wen Sheng , Ma Yun Zhu , Huang Yu Feng , Tang Ya
Published: March 2015

The influence of dislocation density on micromechanical characteristics of Cu6Sn5 and Cu3Sn was studied by nanoindentation. The dislocation density dependent hardness of Cu6Sn5 and Cu3Sn was quantitative analyzed. High dislocation density increased the critical shear stress corresponding to the first pop-in events and induced micro plastic deformation before the first pop-in events. For Cu6Sn5, dislocation creep and lattice diffusion dominate the high stress regime (HSR) and the low stress regime (LSR), respectively, regardless of the dislocation density. High dislocation density increases the stress exponent (n) of HSR, but decrease n of LSR. Dislocation motion is the dominate creep mechanism of unstrained Cu3Sn. After pre strain, the creep behavior of Cu3Sn was divided into HSR and LSR. But dislocation motion is still the dominate creep mechanism. Potential mechanism of the dislocation density dependent micromechanical characteristics was explained based on our experimental results.
Effect of Ag Addition on Growth of the Interfacial Intermetallic Compounds between Sn-0.7Cu Solder and Cu Substrate
Authors: Xie Xiao Chen , Zhao Xiu Chen , Liu Ying , Cheng Jing Wei , Zheng Bing , Gu Yue
Published: March 2015

The effect of Ag content on the morphology of the intermetallic compound (IMC) layer at the interface between Sn-xAg-0.7Cu (x=0.0 wt.%, 0.3 wt.%, 0.8 wt.%, 3.0 wt.%) and Cu substrate has been investigated. After reflow, the slight addition of Ag element can suppress the growth of IMC. However, as the Ag content increases, the thickness of IMC is enhanced. After aging at 150°C, the IMC growth rate constant decreases with the addition of Ag. The IMC growth rate constant of Sn-3.0Ag-0.7Cu is 0.94864×10-5μm2/s, which is the lowest among these solders. As the Ag addition is 0.8wt% and 3.0wt%, the Cu3Sn growth rate constant is 0.16641×10-5μm2/s and 0.18496×10-5μm2/s, compared to the Sn-0.7Cu solder decreased 54% and 49%, respectively. As a result, the addition of Ag element improves the anti-aging properties and suppresses the growth of Cu3Sn layer, which leads to the improvement of solder joint reliability.
Magnetic Properties and Unusual Morphologies of Barium Ferrites Prepared by Electrospinning and Sol-Gel Auto-Combustion Method
Authors: Liu Gui Fang , Fan Run Hua , Yan Ke Lan , Wang Xu Ai , Sun Kai , Cheng Chuan Bing , Hou Qing
Published: March 2015

Barium ferrite fibers and barium ferrite powders were successfully prepared respectively via Electrospinning method and sol-gel auto-combustion method by using Fe (NO3)3·9H2O, Ba (NO3)2 as one of the main raw materials. X-ray diffraction (XRD) and field emission scanning electron microscope (FSEM) were used to study the phase composition and microstructure of barium ferrite. The results showed that barium ferrite fibers consist of a mixture of barium ferrite particles, the diameter of fibers is about 200 nm; barium ferrite powders prepared by sol-gel auto-combustion method were flake barium ferrite compositing of rod-like grains of less than 100 nm in size stacking disorderly. Magnetic properties were investigated by vibrating sample magnetometer (VSM), the results showed that the values of Mr, Ms, and Hc of barium ferrite fibers and powders are quite different due to their different morphologies.
Effects of Ba and Ti Codoping on Stoichiometric and Nonstoichiometric BiFeO3 Multiferroic Ceramics
Authors: Zhou Xi , Xiong Yao , Pei Yu Chong , Chen Wan Ping
Published: March 2015

Bi0.9Ba0.1Fe0.95O3 and Bi0.9Ba0.1FexTi0.05O3 (x=0.95, 0.925, 0.90) ceramics were prepared through conventional solid state reactions. X-ray diffraction analyses indicated that a high content of perovskite phase was obtained for all the four compositions. While the three (Ba,Ti)-codoped compositions all showed a higher resistivity than Bi0.9Ba0.1Fe0.95O3, and Bi0.9Ba0.1Fe0.925Ti0.05O3 had the best electrical and dielectric properties among the three (Ba,Ti)-codoped compositions, including the largest dielectric constant, the smallest dielectric loss at low frequency range, and the highest electrical resistivity. Magnetic hysteresis loop measurement revealed that the four compositions had similarly enhanced magnetic properties. It is concluded that much attention should be paid to fine composition adjustment when multiple elements are co-doped to BiFeO3 system.
A Review on the Characteristics of the New Multiferroic Three-Ply Structure Ferroelectric-Ferromagnetic Nanocomposite
Authors: Zhang Hong Fang , Mak Chee Leung , Wang Yu , Kong L.B. , Chan Helen Lai Wah
Published: March 2015

A new kind of multiferroic three-ply-structured nanoceramic composites consisting of nanosized alloy-based magnetostrictive (MS) and ferroelectric powders (FE) were fabricated successfully by a conventional solid state reaction in air or argon ambient in our previous investigation. But there are still some problems needed to be solved, for example, the magnetic aging and decrease of saturated magnetization phenomena occurred in samples are perhaps related to the harsh preparation conditions such as storage duration and sintering atmosphere and so forth. In this paper, we will review the characteristics of the novel nanocomposites by means of the microstructure and magnetism existed in the samples with nanosized MS powders (i.e. (Tb0.3Dy0.7)0.75Pr0.25Fe1.55, Sm0.88Nd0.12Fe1.93) as fillers. Also, we hope some reasonable explanations and deeper understandings can be concluded about the proposed ageing and magnetism reduction exhibited when the samples were subjected to co-firing in air or argon ambient. Finally, the potential improvement and multifunctional applications in the future are also suggested.
Effect of Mn Substitution on Microstructures, Dielectric and Magnetic Properties of BiFeO3 Ceramics
Authors: Deng Xiao Ling , Cai Wei , Fu Chun Lin , Zhang Yu Qin , Gao Rong Li , Chen Gang , Huang Jia Mu
Published: March 2015

Pure BiFeO3 ceramics and BiMnxFe1-xO3 (x=0.1, 0.15, 0.2, and 0.25) ceramics were prepared by sol-gel method. A structural phase transition from rhombohedral R3c to triangle R3m occurred in Mn-doped BFO ceramics. Mn-doped BFO ceramics exhibited better crystallinity, larger dielectric constant as well as smaller dielectric loss. Besides, a small nonlinearity of magnetization-field curves M(H) was observed, the remanent magnetization increased with the increase of manganese content, and all the BiMnxFe1-xO3 ceramics showed the typical antiferromagnetic, which could be attributed to the effective decrease in the concentration of oxygen vacancies, and the corresponding structural transition.
Preparation and Properties of Nano-Crystalline Cellulose Electro-Rheological Fluid
Authors: Xu Ling Li , Shi Xing Ling , Wang Qing Liang
Published: March 2015

nanocrystalline cellulose (NCC) was prepared from micro-crystalline cellulose (MCC) by strong acid hydrolysis. The characteristics of such particle were studied by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. Electro-rheological fluids (ERF) were prepared by dispersing NCC and MCC in methyl-silicone oil, and their ER effects were measured. Experimental results indicated that NCC ERF exhibited a remarkable ER effect. The highest static shearing stress of NCC ERF (3.5 g/ml) was 5.1 kPa at the room temperature under a 4 .2 kV/mm electric field, increased about 5.5 times compared to MCC ERF, and sedimentation of NCC ERF was not observed even after 60 days.
Advances on FeCuNbSiB Nanocrystalline Soft Magnetic Powder Cores
Authors: Lv Wei
Published: March 2015

For the past few years, nanocrystalline soft magnetic alloy has become hot topic in the field of strategic functional materials based on its excellent magnetic properties and advantages of energy saving, low cost, etc. With rapid innovationof various new type soft magnetic materials, FeCuNbSiB soft magnetic powder cores havebeen gradually turning into researching focusin soft magnetic material field for its excellent high frequency properties, such as high magnetic permeability (μ) and quality factor (Q), low core loss (Pc) and coercivity (Hc), etc.This paper mainly reviews the recent advances and technological achievements of FeCuNbSiB nanocrystalline soft magnetic powder cores, and also provides a brief introduction of FeCuNbSiB/Mn-Zn ferrite powder core, one new type composite magnetic powder core. Finally, future developing trend for FeCuNbSiB nanocrystalline powder cores isalso prospectedcompendiouslyin the paper.
Preparation and Magnetic Properties of Nanocrystal Bulk SmCo7 Magnets
Authors: Shen Qian , Ma Yi Long , Dong Jun , Chen Deng Ming
Published: March 2015

Two kinds of 2:17R Sm-Co alloys, Sm2(Fe,Cu,Zr,Co)17 and pure binary Sm2Co17 were prepared, and the amorphous powder was prepared by high-energy ball milling Sm-Co alloys. The bulk nanocrystalline SmCo7 was prepared by hot-pressing the amorphous powder, and the magnetic properties and phase composition were studied. Initial Sm2(Fe,Cu,Zr,Co)17 showed a large value of coercivity while the pure Sm2Co17 almost showed no coercivity. However, after ball milling the grain size of alloys decreased dramatically until completely amorphous. Two kinds of alloys showed the different phase composition and magnetic properties after hot-pressing. It was found that the pure Sm2Co17 bulk magnet showed a high coercivity Hc and had the 1:7H phase. On the other hand, the Sm2(Fe,Cu,Zr,Co)17 showed high saturation magnetization Ms and very low Hc since the Fe-Co and Sm2Co3 phase were precipitated from the alloy.
Preparation of the Nanoceria Powder from Bastnasite
Authors: Feng Qiang , Qiu Ke Hui , Chen Si Zhu , Yan Guo Yin
Published: March 2015

A novel process was developed to obtain high content of ceria powder directly from bastnasite mineral. The bastnasite was roasted with NaHCO3 at 550 oC for 2 h, washed with water and dilute HCl respectively to remove impurities, and finally calcined in air. TG-DTA, XRD, XRF, SEM was used to characterize the decomposition process of bastnasite, crystalline phase, the chemical composition, and morphology of the product. The results showed that the concentration of HCl solution was the most important factor in the leaching process, and the calcining temperature of bastnasite mineral should be controlled below 600 oC. The optimal technological parameters were suggested as follows: leaching temperature at 45 oC, for 45min in 3 mol/L HCl, with the weight ratio of solid to liquid of 1:5, and the calcining of the leachate at 600 oC for 2 h. And the high content of ceria (TREO > 80wt %, Ceria/TREO > 85wt %) nanosized (20~100 nm) powder was obtained succeffully, which showed potential application in polishing materials.
Effect of V(C,N) Master Alloy on the Grain Size of Low Carbon High Strength Bainite Steel
Authors: Lyu Quan , Wen Hao Yu , Tang Zheng Hua , Hu Qi , Cheng Bo
Published: March 2015

The V(C,N) nanometer powder master alloy was added into a low carbon high strength bainite steel to refine grain size, and its refinement action with that of Ti addition was compared. The experimental specimens were melted in 25kg induction furnace with 0.03%Ti, 0.15%, 0.24%, 0.31% and 0.50% V(C,N) addition, respectively. The specimens were observed by optical microscope, XRD and EDS. The results showed that 0.03%Ti addition refined to the grain size to 13μm-18μm in the research steel, but to 6.5μm-10μm in the case of 0.31% V(C,N) master alloy. And the 0.31% V(C,N) addition has better refining effect than 0.15, 0.24% and 0.50%V(C,N) addition. The microstructure of research steels was lower bainite and martensite for all specimens.
Effect of Sintering Temperature on Microstructure and Mechanical Properties of Ti Mo Alloys
Authors: Fan Xing Ping , Wang Ben Ju , Ren Xiao Qing , Peng Fu Chang
Published: March 2015

The medical Ti-20Mo alloys were fabricated by powder metallurgy. The effects of sintering temperature on the phase, the morphology and the mechanical properties of Ti-Mo alloys were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical properties test methods. The results showed that after sintering at 1200 °C, the microstructure of Ti-Mo alloys mainly consisted of α phase. The increasing sintering time could promote α→β phase transition, thus the flexural strength and the elastic modulus of Ti-Mo alloys could be controlled. When the sintering temperature was 1300 °C, molybdenum content was 20%, the bending strength and the compressive strength of Ti-20Mo alloy were 1369MPa and 2602MPa respectively, and the elastic modulus was 3.4GPa. It may be concluded that the Ti-20Mo alloys is prospective prostheses materials.
Process Control of Buried Layer Epitaxy by Barrel Type Furnace
Authors: Wang Yin Hai , Zhao Jian Jun , Luo Hong , Ma Lin Bao
Published: March 2015

Though the quality of epitaxial wafer prepared by barrel type epitaxial furnace is inferior to that by traditional single wafer furnace, it has a series of advantages such as high yield and low cost. The key issues and difficulties of the epitaxy process for buried layers IC wafers prepared by barrel type epitaxial furnace were discussed. By optimizing the epitaxy process parameters and tightly controlling the production procedure such as cleaning and inspecting, barrel type epitaxial furnace can meet the special requirement for buried layer epitaxial process. The characteristics of the epilayers prepared by barrel type epitaxial furnace were close or equivalent to that by single wafer furnace. The ways to suppress the auto doping in the double buried layer epitaxial process were introduced. The ideal transition width of the epilayers was obtained by the two-step epitaxy.
Synthesis and Photoluminescence Property of Ca3Y2-xSmxWO9 Phosphors
Authors: Ru Jing Jing , Zhou Mei Zhen , Zhao Bing , Yan Gui Yang , Ying Shao Ming
Published: March 2015

A series of novel reddish-orange phosphors Ca3Y2-xSmxWO9were synthesized by solid-state method and characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) spectra. The results showed that these phosphors are tetragonal structures. The optimum calcining temperature was 1100°C, and the sintering time was 3h. The results demonstrated that the optimal doping concentration of Sm3+in Ca3Y2WO9was about 1 mol%. The main emission line was4G5/2→6H7/2transition of Sm3+at 593nm, and showed intense reddish-orange.
Luminescence Properties of Phosphor (Sr1-xBax) 1.95 SiO4: 0.05Eu2+
Authors: Jiang Zi Xu , Qiu Ke Hui , Lu Xue Guang , Zhao Kun , He Xia
Published: March 2015

The luminescence properties of green-yellow emitting (Sr1-xBax)1.95SiO4:0.05Eu2+ (0≤x≤1) phosphors were discussed in this paper. These phosphors were synthesized through the high temperature solid-state reaction technique and characterized by X-ray diffraction. The experimental results indicated that all the major phase of prepared phosphors gradually varied from α-Sr2SiO4 (x=0) phase to Ba2SiO4 (x=1) phase, and an intermediate phase between the two phases was observed at x=0.5. The excitation spectra (λem λem=524 nm) and emission spectra (λex λex=400 nm) showed a broad band character with peak located at 365 nm and range from 579 nm to 508 nm, respectively. With the increase of concentration of barium, the thermal stability of the phosphors increased first when x is less than 0.5, and then it decreased when x surpasses 0.5. In addition, luminescence intensity was enhanced with the barium concentration. Under the 400 nm NUV light excitation the (Sr1-xBax) 1.95SiO4:0.05Eu2+ phosphors have a potential application in white LED.
Fabrication and Compressive Properties of Porous Ti6Al4V Alloy with Elongated Pores for Biomedical Application
Authors: Li Fu Ping , Li Jin Shan , Liu Ge Jun , Kou Hong Chao , Xu Guang Sheng , Zhou Lian
Published: March 2015

Porous Ti6Al4V alloys with anisotropic structure for biomedical application was fabricated by diffusion bonding of titanium alloy meshes. Compressive mechanical compatibility of the alloys is investigated as human bone implants. It is concluded that the fabrication processing for porous Ti6Al4V alloys has better control of the porosity. The pore structure of porous titanium is anisotropic, with elongated and square pores in the out-of-plane and in-plane direction, respectively, which is suited for bone ingrowth. The compressive Young’s modulus and yield stress of porous Ti6Al4V alloy compressed in the out-of-plane direction are 12.2 GPa and 171.4 MPa, respectively, which is compatible with those for the cortical bones.
Fabrication and Biological Properties of Bionic Structure Porous Alumina Ceramics with Spherical/Lamellar Pores
Authors: Tang Yu Fei , Miao Qian , Liu Ying , Wu Zi Xiang , Zhang Wei , Zhao Kang
Published: March 2015

In order to solve the problem that low pore connectivity of the spherical porous ceramic, bionic structure porous alumina ceramics with spherical/lamellar pores were fabricated combining the adding pore-forming agent and two step freeze casting. The effects of fabrication parameters of the samples on morphologies, porosity and pore connectivity are investigated. The mechanical and biological properties of bionic structure porous alumina ceramics are also characterized. Results show that porous alumina ceramics with spherical/lamellar pores are obtained, and the lamellar pores pass through the spherical pores, which prove the pore connectivity reach 86.2 %. The mechanical properties are improved by porosity gradient from the inside (highly porous) to the outside (less porous) of porous alumina. Bionic structure porous alumina ceramics with spherical/lamellar pores have better cell growth and absorbance than those with spherical or lamellar pores only since its high pore connectivity.
Controlling Pore Size of Tissue Engineering Scaffolds Fabricated by Electrospinning and Phase Separation
Authors: Zhou Yu , Zhao Qi Long , Wang Min
Published: March 2015

Electrospinning is a versatile and efficient technique for fabricating nanofibrous tissue engineering scaffolds. However, problems such as small pore size of electrospun scaffolds have limited their applications for tissue regeneration. It is important to modify/improve existing electrospinning techniques for fully realizing the potential of both the electrospinning technology and electrospun nanofibrous scaffolds. To increase the pore size of scaffolds prepared by conventional electrospinning technology, in the present study, a hybrid fabrication technique by combining electrospinning with phase separation is utilized. Polymer solutions were made using mixed solvent of (a) DCM and DMF or (b) chloroform and DMF and electrospun fibers were deposited in ice water, ice methanol or liquid nitrogen. It was shown that for poly (ε-caprolactone) (PCL) scaffolds, the hybrid technique could maintain the nanofibrous structure for scaffolds and control the pore size in scaffolds. As compared with pore sizes in PCL scaffolds made by conventional electrospinning, pores were larger in PCL scaffolds produced by the hybrid technique.
Particle Size of 45S5 Bioactive Glass Affected the Enamel Remineralization
Authors: Dong Zhi Hong , Zhou Chang Chun
Published: March 2015

In order to repair the etched human dental enamel, 45S5 bioactive glass with different particle size was used to remineralization enamel in vitro. 45S5 bioactive glass powder was sieved, and divided into the three groups. Freshly sound human second molar teeth from patients were extracted and specimens of dentine-enamel junction were prepared under water-cooled diamond saw, then the enamel surface was polished and finally rinsed. The enamel samples were soaked in simulated oral fluid (SOF) for 5 days. Particle size distribution, topological images and mechanical properties such as hardness and reduced modulus of enamel surface were evaluated by the laser particle size analyzer, atomic force microscope (AFM) and nanoindentation technology. The results indicated that the adhered particle size onto the enamel surface was concentrated on the 1-10 μm. With the decreasing particle size, adhesive capacity onto the enamel surface increased, but the mechanical properties decreased gradually after soaking in SOF for 5 days. In a short period time, Group 2 particles are suitable of repair the etched enamel, and further improve its mechanical properties. This study suggests that proper size 45S5 bioactive glass may be used to repair the acid etched teeth as a toothpaste additive.
Excellent Cell Compatibility in Time Controlled Silk Fibroin Hydrogels
Authors: Zhang Fang , Li Jiao Jiao , Jiang Rui , Zhang Shan Shan , Zhu Tian , Lu Shen Zhou
Published: March 2015

Various methods were developed to prepare hydrogels including photo-cross-linking, chemical cross-linking, enzymatic cross-linking, pH or temperature-induced gelation, ionic interaction, and hydrophobic interactions. Whereas silk fibroin gelation time was difficult to control by physical methods, the cross-linkers used in chemical technique were likely to reduce the cell biocompatibility. Sodium N-Lauroyl Sarcosinate (SNS), an amino acid-based surfactant, came into accelerate silk fibroin to form silk hydrogel. To monitor the gelation process and determine the gelation time, turbidity changes during gelation were measured by Synergy HT. Cylindrical gels have been measured with universal material experiment machine and KES for mechanical properties. Fibroblast (L929) cells were seeded on the surface of hydrogels to investigate the cell compatibility. The results show that the SNS/SF gelation time ranges from 20 min to 120 min, which is affected by environment temperature, the final concentrations of SF and SNS. Compared with pure silk fibroin hydrogels, the compression strength of SNS/SF gel is much stronger. SNS/SF gel has excellent compression-recovery performance in KES test as well. A logarithmic stable cell growth appears on the surface of SNS/SF hydrogels, which indicates that SNS/SF hydrogels have excellent cell compatibility. Therefore, the SNS/SF hydrogels have great potential in tissue repair for surgery.
One-Step Synthesis of Water-Soluble Fluorescent Carbon Dots
Authors: Li Fan , Liu Chang Jun , Yang Jian , Tian Feng , Li Rui Xin , Zhang Li
Published: March 2015

Water-soluble carbon dots (CDs) with high yield were synthesized by a facile, one-step incomplete pyrolytic route under nitrogen atmosphere or air using ammonium citrate as carbon source. Photoluminescence (PL) spectrum, Fourier transform infrared (FTIR) absorption and high-resolution transmission electron microscopy (HRTEM) were used to determine the characteristics of the CDs. Though CDs could be prepared from 150 oC to 400 oC, the highest yield of CDs (17.5%) was achieved at the heating temperature of 150 oC in air, so did the relative quantum yield. The as-prepared CDs showed excellent biocompatibility and had been tentatively used in cell imaging.
Structure Changes of Coating on NiTi Alloy Prepared by Micro-Arc Oxidation in Na2SiO3 Electrolyte
Authors: Feng Dian Wen , Jiang Xun Yong
Published: March 2015

Nickel titanium is a near-equiatomic intermetallic that possesses distinctive and desirable thermomechanical properties. Micro-arc oxidation (MAO) treatment of NiTi can effectively prevent the release of Ni ions from NiTi. In this paper, NiTi is treated with MAO method in Na2SiO3electrolyte. MAO process of NiTi in Na2SiO3electrolyte contains two stages: “growth period”, “jumped period”. During the process of MAO, Ni in NiTi is oxidized to Ni ion, and the Ni ions are dissociated in electrolyte. Ti was left in NiTi, which generate much Ti content appearing on the surface of the sample, and contribute to prerequisites for the reaction. After the applied voltage reaches a certain value, Na2SiO3electrolyte participate in the reaction and form insulating amorphous silicon oxide layer. With the increase of thickness of insulating layer on NiTi, the anodic voltage increase. When applied voltage excess certain threshold, discharge spark appear on the surface of NiTi.
Titanium Nitride Modified by Hydrothermal Treatment in Calcium Acetate Solution
Authors: Shi Xing Ling , Xu Ling Li , Zhou Guang Hong , Bang Le Te
Published: March 2015

Dental implant made of pure titanium (Ti) has become one important option to restore the function of lost tooth. However, because of insufficient hardness, it is always scratched during oral hygieneprocedures. To improve its surface hardness,titanium nitride (TiN) coating was prepared. Soft tissue - implant interface is important for blocking bacteria invasion, therefore surface modification is necessary to improve biocompatibility of TiN for fibroblasts.In the present study, TiN coating was modified by hydrothermal treatment incalcium acetate (CaAc) solution and effect of hydrothermal treatment temperature was studied. After treatment,calcium (Ca) wassuccessfully combined into TiN surface and the surface morphology, roughness and hardness were not changed below 140 °C. It is expected that, surface modification with Ca by hydrothermal treatment could made TiN a promising dental implant coating.
Synthesis and Characterization of Polythiophene Derivatives with Different Alkyl Substitution Groups
Authors: Chen Wei Xing , Gu Yong Qiang , Luo Chun Yan , Zhang Xiao Long
Published: March 2015

Three kinds of poly (3-alkylthiophene), such as poly (3-butylthiophene) (P3BT), poly (3-hexylthiophene) (P3HT) and poly (3-dodecylthiophene) (P3DDT) were prepared by the Grignard Metathesis Method (GRIM). Their chemical structures are characterized by FTIR,1H-NMR and GPC.1H-NMR result shows that regioregular structure of these polymers is relatively higher. The GPC results show that the molecular weight of the polymers is 8.42×104, 1.06×105and 1.21×104g/mol with molecular weight distributions of 1.41, 2.18 and 1.18, respectively. The DSC result shows that the glass transition temperature of three kinds of polymers is 120.8, 146, 118 °C, respectively. UV absorption spectrum and fluorescence spectroscopy of three polymers in THF solution show that the maximum absorption wavelength is 448 nm, 470 nm, 390 nm, and the maximum emission wavelength is 531, 535, 527 nm with the band gap of 2.06, 1.86, 2.21 eV, respectively.
Structures and Electronic Properties of a Si55 Cluster on DFTB Calculations
Authors: Wu Li Jun , Zhang Lin , Qi Yang
Published: March 2015

The lowest-energy geometrical structures of a cluster containing 55 atoms were searched by using the Density Functional Tight Binding (DFTB) combined with unbiased global optimization genetic algorithms (GAs) method. Two lowest-energy structures were obtained for the Si55 cluster with the appearance of “Y shape” and “like-spherical shape” configurations. The configuration dependence average energy, highest occupied and lowest unoccupied molecular (HOMO-LUMO) gap, electron transfer and molecular dipole moment were also discussed in details for this cluster.
Structural Evolution and Mechinical Properties of Copolyamide Fibers during Thermal Annealing
Authors: Li Ke , Luo Long Bo , Huang Jie Yang , Yao Jing , Wang Hui Na , Feng Yan , Liu Xiang Yang
Published: March 2015

Modified aramid (PBIA) containing benzimidazole units in the main chain were synthesized and the corresponding PBIA fibers were prepared by wet spinning and then annealed at different temperatures. The mechanical properties and the structure of copolyamide PBIA fibers were investigated for different annealing temperatures. The results of thermogravimetric analysis showed that the decomplexation reaction between HCl and benzimidazole occurred during the annealing process and HCl was completely removed at 320°C. The decomplexation of HCl also leads to the formation of hydrogen bonds between benzimidazole fragments, resulting in the rearrangement of the molecular chain and a more ordered macromolecular structure. The mechanical properties, chain orientation could be significantly improved when the samples were annealed in the temperature range from 280 to 320 °C. In addition, the analysis of self-elongation during the annealing process further indicates that the macromolecular chains were more ordered after the decomplexation of HCl. In addition, the PBIA fibers firstly annealed at 300°C which the decomplexation reaction between HCl and benzimidazole occurred, and then annealed at 400°C, resulting the higher PBIA fibers are obtained.
Solvent-Induced Crystallization of Polyarylene Sulfide Sulfone
Authors: Li Su Ying , Gong Yue Wu , Long Sheng Ru , Wang Xiao Jun , Yang Jie
Published: March 2015

In this paper, N-methyl-2-pyrrolidone (NMP) induced crystallization behavior of PASS was found and studied. To study NMP induced crystallization of PASS, Differential Scanning Calorimeter (DSC), X-Ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) were employed. The results showed that the crystal induced by NMP was consistent with precipitates obtained in solution, and was the eutectic of PASS and NMP. With the induction time increased, crystalline region continued to improve and the crystal size became bigger.
Polymerization of Dicyclopentadiene/Styrene in PolyHIPE
Authors: Xu Wang Fa , Sun Fa Meng , Liu Jing Bo , Li Xiao Fang , Zhang Fa Ai
Published: March 2015

A series of porous poly(styrene-divinylbenzene) monoliths (polyHIPE) was synthesized by high internal phase emulsions (HIPE). The effects of the ethanol contents on the microstructure of the polyHIPE were characterized by scanning electron microscopy and mercury intrusion porosimeter. The adsorption and release behaviors of the polyHIPE for a monomer mixture consisting of dicyclopentadiene (DCPD) /styrene (St) (DS, mass ratio of 9/1) were investigated. The polymerization of the mixture DS within pores of the polyHIPE was studied. The results showed that the microstructure of the polyHIPE was significantly influenced by the ethanol content. The increase of ethanol in the HIPE increased the internal pore diameter and decreased the pore volume of the polyHIPE, thus decreased the DS absorption and increased the release rate. The DS monomer can enter the pores(cavities, windows) and fill the original holes after the polymerization. Compared with conventional polymerization of DCPD/St, the poly(DCPD/St) (pDS) obtained from confined spaces possess higher molecular weight, broader molecular weight distribution, and higher Tg. As the pore diameter increased, the effect of space confinement reduced, and the performances of pDS were closed to that prepared by conventional polymerization.
Uniformly Dispersed Poly(ethylene glycol) Functionalized Graphene Oxide/Poly(L-lactic acid) Nanocomposites with Balanced Mechanical Properties
Authors: Zhang Zi Jing , Zhou Yan Ni , Liu Huan , Zhu Le Min , Li Zhong Ming , Ran Rong
Published: March 2015

Balanced mechanical properties are always the goal of high-performance general plastics for engineering purposes. In order to develop uniformly dispersed graphene oxide/poly(L-lactic acid) nanocomposites with balanced mechanical properties, a poly(ethylene glycol) (PEG) grafted graphene oxide was introduced into poly(L-lactic acid) (PLLA) matrix. The PEG grafted graphene oxide (GEG) was confirmed by the results of fourier transform infrared (FTIR) spectra and thermal gravimetric analysis (TGA). Then the mechanical properties of the nanohybrids were measured. The results showed that in contrast to the aggregation of GO, GEG could uniformly disperse in PLLA matrix. An intriguing phenomenon is that thanks to the strong interfacial interaction between GEG and PLLA, it exhibits a substantial enhancement of the elongation at break (EB) as well as a simultaneous improvement of the tensile strength (TS), while the addition of GO decreases the EB of PLLA matrix. This work provides a potential industrialized technique for high-performance PLLA nanocomposites
Study on Synthesis of IPDI-Based Waterborne Polyurethane
Authors: Zheng Lin Lu , Chen Lu
Published: March 2015

An IPDI-based waterborne polyurethane emulsion(WPU) was synthesized by the reaction of polyester glycol(PBA), di-methylol propionic acid(DMPA) with isophorone diisocyanate (IPDI) instead of toluene di-isocyanatotoluene(TDI) because of its low toxicity, low saturated vapor pressure. The factors influencing the properties of IPDI -based WPU were discussed. It was observed that the appearance and properties of the IPDI -based WPU were nearly related with the ratio of NCO/OH(R) and the amount of DMPA.
Synthesis, Characterization and Performance of Superplasticizer with a Multi-Arm Structure
Authors: Liu Xiao , Wang Zi Ming , Zhu Jie , Zhao Ming , Zheng Yun Sheng
Published: March 2015

A novel superplasticizer with a multi-arm structure, i.e., a “core” connected with multiple copolymer “arms”, was synthesized through two steps including an esterification reaction between polyhydric alcohols and acrylic acid and a copolymerization reaction in an aqueous solution among the esterification product, isobutenyl polyethylene glycol and acrylic acid. The reaction conditions were determined, and the results showed that the esterification rate can reach above 95% with a water-carrying agent of 70g, a catalyst/alcohol molar ratio of 0.07, an inhibitor/monomer molar ratio of 0.03, and a reaction time of 7 hrs. The reaction products were characterized by 1H Nuclear Magnetic Resonance (1H NMR) and Fourier Transform infrared spectroscopy (FTIR). It is confirmed to be the multi-arm structure, and the self-synthesized superplasticizer with a multi-arm structure exhibited higher energy efficiency, which was in accordance with its excellent paste fluidity performances and adsorption behavior in cement paste
Negative Permittivity of CNTs–Epoxy Composites Prepared by Cryomilling
Authors: Hou Qing , Fan Run Hua , Zhang Zi Dong , Yan Ke Lan , Cheng Chuan Bing , Chen Min , Sun Kai , Wang Xu Ai , Li Qian Qian
Published: March 2015

In this paper, epoxy resin was used as matrix to prepare composite cryomilling at liquid nitrogen temperature in which the content of CNTs powder vary from 25 wt% to 40 wt%. The microstructure and dielectric properties of the composite were analyzed by SEM and RF impedance material analyzer. The result showed that permittivity of the composites turned negative after the CNTs reached certain content. The plasma oscillation of delocalized electrons in CNTs conductive networks causes negative permittivity phenomenon.
Development of Precious Metal and its Alloy Sputtering Targets with High Performance
Authors: He Jin Jiang , Liu Shu Qin , Luo Jun Feng , Wang Yue , Gao Yan , Xiong Xiao Dong
Published: March 2015

High-purity precious metal and its alloy targets make a very important role in semiconductor manufacturing. In this paper, the preparation methods of high performance sputtering targets (including silver, platinum and its alloy, ruthenium materials) for advanced semiconductor manufacturing were introduced. The relationships between deposited film behaviors and sputtering target properties in some applications were also discussed. In order to acquire high quality thin film, the properties of sputtering target such as density, alloy composition homogeneity, grain size and uniformity et al. have to be well controlled by proper fabrication techniques.
Electroless Copper Plating on Polyester Fabric Modified with Silane through Supercritical Carbon Dioxide Process
Authors: Guo Rong Hui , Yan Wan Qi , Lan Jian Wu
Published: March 2015

Polyester fabric was pretreated with 3-aminopropyltrimethoxysilane (APTMS) through supercritical carbon dioxide (scCO2) process before electroless copper plating. APTMS pretreated polyester fibers were characterized by contact angle. Deposit weight, surface morphology and electromagnetic interference (EMI) shielding effectiveness (SE) of electroless copper plated polyester fabrics were investigated. The results show that polyester fibers are covered with APTMS after APTMS modification in scCO2 medium. Copper coatings on the polyester fibers are uniform after copper plating. Electromagnetic interference shielding effectiveness of the copper plated polyester fabric arrives at 60-80dB at frequencies ranging from 2 to 18 GHz.
Progress in Preparation of Phenolic Fibers by Electrospinning
Authors: Xie Gai , Liu Yong , He Hong , Wang Ke Jian
Published: March 2015

Phenolic fiber is a versatile material. This article focused on introduction of the progress of generating phenolic fibers using solution electrospinning method and its applications, as well as the trail exploration of preparing phenolic fibers by melt electrospinning. For the research on preparation of phenolic fibers using solution electrospinning, researchers added polymers or additive agents to adjust the viscosity and electrical conductivity of the spinning solution. Then they cured and carbonized the electrospun fibers to reach their varied aims. After these two processes, the brittle nature of the phenolic fibers has been greatly changed. What’s more, the modification makes it easier to be dealed with in the analysis tests and be more suitable to be applied as adsorbent materials, nonconductive materials, and flexible materials.
Effect of Heat Setting Methods on Structures and Properties of High Strength Polyvinyl Alcohol Fibre
Authors: Zhu Yin , Zhao Jiong Xin
Published: March 2015

The effect of heat setting methods on the structures and mechanical properties of high strength polyvinyl alcohol (PVA) fibre is studied in this article. The microstructure and mechanical properties of heat treated PVA fibre is investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and single fibre electronic tensile strength tester. Results show that the heat setting method with constant tension is a good heat setting method which can largely enhance the tensile strength of PVA fibre. During the heat setting process, the mechanical properties of PVA fibre are greatly affected by the temperature, tension and setting time. When the temperature is 220°C, tension is 5cN/dtex and setting time is 90sec, the tensile strength of PVA fibre increases from 12.0cN/dtex to 16.4cN/dtex in compare with the PVA fibre without heat setting
A Very Thin Layer of NiO, Ni(OH)2 Nanosheets Arrays with Organic Functional Modification of Polyaniline
Authors: He Xiao Chun , Si Zhen Mei , Li Dong Mei , Zhang Bo , Gao Ming Jun , Ma Xing Fa , Li Guang
Published: March 2015

NiO, conductive polymers have many important applications in supercapacitor, lithium-ion batteries, H2production with photocatalysis, chemical sensors, biosensors, electrochromic, environmental fields, and so on. Due to P-type semiconductors of NiO and polyaniline, the NiO/Polyaniline (PANi) would be a new nanocomposite with synergistic behaviors or complementary properties. Different morphologies of NiO were synthesized with hydrothermal method. NiO nanosheets arrays on glass substrate were obtained with optimized condition. And the NiO nanosheets arrays were immersed in the solution of aniline accompanying chemical oxidation reaction. The results indicated that a very thin layer of NiO, Ni (OH)2nanosheets arrays with organic functional modification of polyaniline were formed on glass substrate due to acid etching effects. The results of XRD showed that the presence of NiO and Ni (OH)2in prepared film were observed. The FTIR results also confirmed that this very thin film contained the components of polyaniline. This method is very simple, which would be used in many film electrodes for photocatalysis fields, supercapacitor, sensors, et al.
Fabrication and Evaluation of an Amino Modified Epoxy Coating for Anti-Scouring and Anti-Corrosion Application
Authors: Wang Zhi De , Li Jing , Guan Zhen Wei , Zhang Yu Zhong , Wang Yan , Wang Zhi Yong
Published: March 2015

Excellent performance is necessary for compressor blade when aircraft engine serves in harsh environment, where it will go through scouring from jet-stream and extraneous sand, shaking of blades and corrosion from corrosive medium, taking moisture, salt, SO2 for example. Due to the shortage of scouring resistant and anti-corrosion property, shedding of damaged coating is a fundamental reason for the breakdown of aircraft engine blades, which is also the technique bottleneck that hinders the engineering application of compressor blades. Aiming at such problems, an amino modified epoxy coating which performed excellent scouring resistent and anti-corrosion property was fabricated on blades in this paper. Physical properties, anti-corrosion performance, abrasion resistant profiles and scouring resistant test were comprehensively evaluated. Results showed that the coating displayed a high hardness (pendulum hardness 0.9), overlong pot life, well anti-corrosion performance and excellent scouring resistant property. Pot life extends from 8h which is that of common coatings to 36h, so that it is benefit to large scale coating in engineering application. The anti-corrosion performance is similar to traditional aluminizing/inorganic silicate protect coatings, and abrasion resistant property is superior to common protect coatings. Moreover, scouring resistance performance is 3~4 times that of traditional coatings. Hence, such protective coatings could ensure the long lasting of blades protection.
Ru Thin Film Formation Using Oxygen Plasma Enhanced ALD and Rapid Thermal Processing
Authors: Zhang Chun Min , Liu Xiao Yong , Zhang Lin Qing , Lu Hong Liang , Wang Peng Fei , Zhang David Wei
Published: March 2015

A novel Ru thin film formation method was proposed to deposit metallic Ru thin films on TiN substrate for future backend of line process in semiconductor technologies. RuO2 thin films were first grown on TiN substrate by oxygen plasma-enhanced atomic layer deposition technique. The deposited RuO2 thin films were then reduced into metallic Ru thin films by H2/N2-assisted annealing.
Effects of Cobalt Nanoparticles Addition on Shear Strength, Wettability and Interfacial Intermetallic Growth of Sn−3.0Ag−0.5Cu Solder during Thermal Cycling
Authors: Gu Yue , Liu Ying , Zhao Xiu Chen , Wen Shu Lai , Li Hong , Wang Yuan
Published: March 2015

In the present study, Cobalt nanoparticles were synthesized and mixed with Sn-3.0Ag-0.5Cu solder (SAC305). The effect of 0.05 wt.%, 0.2 wt.%, 0.5 wt.% and 1.0 wt.% Co nanoparticles on the wettability, the shear strength as well as the growth of intermetallic compounds (IMCs) at composite solder/Cu interface during thermal cycling were investigated. Results show that Co nanoparticle addition can considerably improve wettability, increase the shear strength and suppress the growth of interfacial IMCs. The addition amount of Co nanoparticles have the consistent relation with the improvement extent of the wettability, shear strength and the growth rate of interfacial IMCs. Slight addition (0.05 wt.% and 0.2 wt.%) can significantly improve the properties of nanocomposite solder in all the three aspects. However, with excessive addition amount (0.5 wt.% and 1.0 wt.%) of Co nanoparticles, the improvement extent will decline. The Cross-section images of the interface of nanocomposite solder/Cu joint show that Co can form reinforcement particles in the solder and can act as the sacrificial element to substitute Cu to react with Sn. Excessive Co nanoparticles would form large amount of hard and brittle intermetallics which leads to decreasing shear strength of the composite solder.
New breeding of Eurasian Dotterel Eudromias morinellus in the Italian Alps
Authors: Bassi Enrico , Viganò Enrico , Scieghi Gianfranco
Published: March 2015

Eurasian Dotterel Eudromias morinellus is a summer visitor to northern Europe, but occurs more patchily farther south, with Europe accounting for less than half of its global breeding range. It has an extremely large range with an European breeding population relatively small (<42,000 pairs), but was stable between 1970-1990. Spain hosts the largest breeding population of Southern Europe (Gutiérrez 1997; Valle & Scarton 1999). Over the Alps the species is threatened of extinction due to its small population size. The main breeding alpine population settled in Austria with a maximum of ten reproductive pairs since 2003. In Switzerland after two breeding events recorded in the Grisons in 1965 and 1998, three more broods occurred in 2012 and 2013. In Italy the main reproductive population, varying from 1 to 6 pairs, is located in Abruzzo’s Apennines whereas from 1974 to 1994 several breeding events were recorded. Last breeding was confirmed up to 1994. In the Italian Alps breeding was suspected in few instances, but it was only confirmed in 1978 (one pair plus another possible one in South Tyrol) and 1994-95 in Lombardy region (one pair in Upper Valtellina).
Bird assemblages on a Mediterranean sandy beach: a yearly study
Authors: Battisti Corrado
Published: March 2015

Around the 2007 yearly cycle, we carried out a transect in a Mediterranean sandy beach (central Italy), a structurally oversimplified ecosystem, elaborating the data in six bimonthly periods and in three longitudinal habitat types. We observed 25 bird species. Assemblages appear heterogeneous at taxonomic-, phenological- and ecological-level. Also normalizing (Margalef index), in winter the beach hosted the richest assemblage, in summer-autumn the lowest. The inner dunal area appears the richest habitat type. Here, the presence of vegetation presumably permits the occurrence of a large availability of different trophic resources for different species. Beaches represent patchy ecosystems with a different availability of resources in space and time that host heterogeneous bird assemblages, different in their ecology and phenology around a yearly cycle.
Ornitologia Cuneese. Indagine bibliografica e dati inediti
Authors: Chiozzi Giorgio
Published: March 2015

Book Review:

Ornitologia Cuneese. Indagine bibliografica e dati inediti
Caula Bruno, Beraudo Pier Luigi
Preparation of the Professional Athletic Trainer: A Descriptive Study of Undergraduate and Graduate Degree Programs
Authors: Cavallario Julie M. , Van Lunen Bonnie L.
Published: March 2015

Context

The examination of the appropriate professional degree for preparation as an athletic trainer is of interest to the profession. Descriptive information concerning universal outcomes is needed to understand the effect of a degree change.

Objective

To obtain and compare descriptive information related to professional athletic training programs and a potential degree change and to determine if any of these factors contribute to success on existing universal outcome measures.

Design

Cross-sectional study.

Setting

Web-based survey.

Patients or Other Participants

We contacted 364 program directors; 178 (48.9%; 163 undergraduate, 15 postbaccalaureate) responded.

Intervention(s)

The survey consisted of 46 questions: 45 questions that dealt with 5 themes (institutional demographics [n = 13], program admissions [n = 6], program outcomes [n = 10], program design [n = 9], faculty and staff [n = 7]) and 1 optional question.

Main Outcome Measure(s)

Descriptive statistics for all programs were calculated. We compared undergraduate and postbaccalaureate programs by examining universal outcome variables.

Results

Descriptive statistics demonstrated that 33 programs could not support postbaccalaureate degrees, and a substantial loss of faculty could occur if the degree requirement changed (553 graduate assistants, 642 potentially underqualified instructors). Postbaccalaureate professional programs had higher 2011–2012 first-time Board of Certification (BOC) passing rates (U = 464.5, P = .001), 3-year aggregate first-time BOC passing rates (U = 451.5, P = .001), and employment rates for 2011–2012 graduates employed within athletic training (U = 614.0, P = .01). Linear multiple-regression models demonstrated that program and institution type contributed to the variance of the first-time BOC passing rates and the 3-year aggregate first-time BOC passing rates (P < .05).

Conclusions

Students in postbaccalaureate athletic training programs performed better in universal outcome measures. Our data supported the concerns that this transition could result in the loss of some programs and an additional immediate strain on current staff due to potential staffing changes and the loss of graduate assistant positions.