bluuebunny/crossref_metadata_2025 huggingface dataset:
The predictability of financial, accounting‐based, and industrial factors on the success of newly incorporated Spanish firms
Authors: Tong Yehui , Saladrigues Ramon
Published: February 2018

Purpose: The purpose of this paper is to identify the impacts and predictability of financial, accountingbased, and industrial factors (as well as corporate venturing) on survival‐based success of newly incorporated firms in Spain.Design/methodology/approach: Logistic regression is used for comparing the differences of factors in the prediction of future success after different time periods since the studying years (age 1, age 2, and age 3 respectively) in manufacturing and distributive sectors.Findings: Differences in predictability are observed between manufacturing and distributive sectors: it is obvious in distributive sector (rather than manufacturing sector) that liquidity, bank credit, trade credit, and concentration are positively related to success while entry rate is negatively related to success. In spite of that, some factors still show strong predictability in both two sectors. Firm size and profitability are the strongest positive factors, which are followed by corporate venturing and the growth of industrial operating revenues with positive and generally negative relationships to success separately. Besides, for some factors and variables frequently showing statistical significance, their impacts in the same age tend to be relatively stable.Practical implications: The findings of this paper can help to identify the predictability of different factors on the success of newly incorporated firms and catch the differences between manufacturing and distributive sectors.Originality/value: This paper enriches the empirical study of new firm success in Spain in depression and stagnant environment (because the observed years here are from 2009 to 2014); besides, the findings also contribute to the specific prediction study of manufacturing and distributive sectors.
Individual variability in cue weighting for first-language vowels
Authors: Ghaffarvand Mokari Payam , Werner Stefan
Published: February 2018

This study investigates the use of different cues in discrimination of Azerbaijani /oe/ and /ɯ/ vowels. Regarding the large overlap in f1-f2 vowel space in the production of these vowels, this study researched for other possible cues in their categorization. Twenty native Azerbaijani listeners were tested through a perceptual identification test. Since f2 was weighted more consistently through the experiment, it is suggested that f2 is the primary cue in discriminating of this vowel pair. We observed individual differences in the perceptual weighting of f2 and f3 among the listeners. Although most of the participants gave more weight to f2, some others weighted f3 heavier than f2 or gave weight to both cues equally. These findings expand the knowledge on perceptual cue weighting and point the importance of examining cue weighting at the individual level.
Democratização e acessibilidade no ensino superior em Portugal: mudanças recentes
Authors: Cerdeira Luisa , Cabrito Belmiro
Published: February 2018

Em Portugal, desde há algumas décadas, assistiu-se a um crescimento explosivo da procura de ensino superior, o mesmo ocorrendo, aliás, com o número de graduações, evidenciando um processo de construção de um ensino superior de massas. Todavia, este crescimento terá tido efeitos significativos no nível de acessibilidade e na democratização do sistema? São estas as interrogações que fundamentam o presente artigo. Nesse sentido, os autores apresentam alguns conceitos de acessibilidade (geral e financeira) e, a partir do valor de indicadores de natureza académica (taxa real de escolarização e de graduação do ensino superior) e de natureza financeira (custos totais de educação, PIB per capita e Rendimento Mediano do País), bem como da estrutura económico-social dos estudantes do ensino superior em Portugal, em duas datas distintas, 2010 e 2015, discutem a evolução da acessibilidade e a democratização do ensino superior português, no período 2010-2015. Os autores concluem ter ocorrido um ligeiro acréscimo quer do nível de acessibilidade quer dos estratos sociais de recrutamento do ensino superior, mas permanecendo o país, ainda assim, muito aquém do que se verifica em alguns dos países parceiros de Portugal na União Europeia.
Superplastic Deformation Behavior and Cavity Formation of Ti55 Titanium Alloy
Authors: Liu Zhang Guang , Li Pei Jie
Published: February 2018

Ti55 is a type of new near-α titanium alloy featuring good heat resistance and thermal stability at a temperature below 550°C. This paper explores the superplastic behaviors of Ti55 titanium alloy sheets at high temperature. The results showed that at a strain rate between 8.3×10-4 and 1.32×10-2s-1 and a deformation temperature between 885 and 935°C, this material exhibited favorable superplasticity. A 872% tensile elongation was achieved even at a high temperature of 925°C and a high strain rate of 1.32×10-2s-1. For a deformation temperature of 925°C and a strain rate range of 8.3×10-4～1.32×10-2s-1, the strain rate sensitivity index (m) was equal to or higher than 0.38, which depends on the specific strain rate and reached its peak at 6.64×10-3s-1. The study showed that tiny cavities tended to appear around the rare earth phase particles. As the deformation temperature and the deformation strain rate increased, both size and volume fraction of the cavities decreased significantly. When the plastic deformation further increased, the cavities experienced not only longitudinal aggregation along the tensile strain direction, but also transverse aggregation normal to the tensile strain direction. The typical high-temperature ductile fracture morphology is related to both aggregation and growth of the large number of microscopic cavities and dimples.
A Comparative Life Cycle Assessment of Typical Foam Glass Production
Authors: Gong Xian Zheng , Tian Ying Liang , Zhang Li Juan
Published: February 2018

Foam glass is a new insulation building materials and plays an important role in building energy efficiency for its many excellent performances, such as small thermal conductivity, low coefficient of thermal expansion and high mechanical strength. Generally, the manufacturing process of foam glass mainly can be classified into two typical processes, the waste glass recycling process and glass melting process. In this paper, the process-oriented life cycle assessment is used to quantitative analyze and evaluate the environmental load, such as energy consumption and pollutant emission of the two typical processes. The results show that the environmental load of the glass melting process takes place in two stages of the foaming and annealing, and the raw material extraction, while the waste glass recycling process mainly come from foaming and annealing. Regarding the energy consumption of foam glass, waste glass process is lower 22.4% than the glass melting process, while carbon emissions is lower 24.8%, and the comprehensive environmental impact is lower 40%. Therefore, the findings will guide and promote the new technology application for the energy saving and green technology applications in foam glass industry.
Rheological Model and Viscoelasticity of Crumb Rubber Modified Bitumen
Authors: Zhang Huang , Yu Jian Ying , Cao Zhi Long , Liu Fei
Published: February 2018

Rheological model for crumb rubber modified bitumen (CRMB) by the rheological testing and model analyzer was investigated in this paper. The effects of crumb rubber content and temperature on rheological model and viscoelasticity of CRMB were conducted. The results illustrate that rheological model of bitumen is transformed from Dashpot into Burgers at 60°C after bitumen has been modified by crumb rubber. And the elasticity of CRMB is increased and the viscosity is decreased with crumb rubber content rising. For the modified bitumen with 20% crumb rubber (CRMB-20), its rheological model is Burgers among 20°C~80°C, but the model is translated into Maxwell at 100°C. As the temperature increases, both viscosity and elasticity of CRMB-20 are increased. Compared with 20°C, the instantaneous elastic and viscous deformation of CRMB-20 at 100°C are increased by 14.2 times and 80.5 times, respectively.
Effects of Heat Treatment on Microstructures and Mechanical Properties of Ti-38644 Alloy for Aerospace Fasteners
Authors: Zhao Qing Yun , Cheng Si Rui , Wang Li Dong , Dong Li Min , Liu Feng Lei
Published: February 2018

The effects of heat treatment on microstructure and mechanical properties of Ti-38644 alloy were investigated by scanning electron microscope (SEM) and transmission electron microscopy (TEM) as well as uniaxial tensile test. The results show that when the solution temperature is lower than 845°C, the microstructure of Ti-38644 alloy is equiaxed β phase with the grain size of 20μm, and the tensile strength is about 960MPa. As raising solution temperature to 860°C, the grain size of Ti-38644 alloy increases to 100μm and the tensile strength decreased to 870MPa. There are a large number of secondary α phase precipitated from the grain boundaries and within grain of β phase undergoing aging treatment. Secondary α phase coarsens with increasing the aging temperature, leading to the decrease of tensile strength. After solution treatment at 815°C for 1.5h, water quenching plus aging at 520°C for 10h, air cooling, Ti-38644 alloy shows a better mechanical property with the tensile strength 1330MPa, elongation and reduction of area 10% and 45% respectively.
Microstructure Analysis and Creep Behaviour Modelling of Powder Metallurgy Superalloy
Authors: Xu Wen Yong , Peng Zi Chao , Li Mu Zi , Pham Minh Son
Published: February 2018

Microstructure analysis of Ni-based superalloy FGH96 under different ageing treatments were carried out in order to understand the microstructure-creep strength relationships of the alloy. It was found that the volume fraction of tertiary γ′ and the mean γ-channel width was significantly varied with different ageing treatments, leading to the changes in creep behavior. The dislocation/γ′ shearing mechanisms were also changed with ageing treatment. The volume fractions of both secondary and tertiary γ′ and the mean γ-channel width were quantitatively analyzed by electron microscopy. The quantified microstructures were used for a crystal plasticity-based constitutive model. It was observed that the crystal plasticity model can accurately simulate experimentally observed creep behavior of aged samples showing significant secondary creep stage.
Numerical Simulation of Combustion Resistant Titanium Alloy Wear Behavior at High Temperature Fields
Authors: Liang Xian Ye , Mi Guang Bao , He Liang Ju , Li Pei Jie
Published: February 2018

The abnormal local friction and wear phenomena usually generate during the service of the titanium alloy rotor /stator parts of the aero engine compressor under high temperature conditions. This phenomenon is the main cause of the occurrence of titanium fire failure and has great harm. In the present investigation the friction and wear behavior of the combustion resistant titanium alloy at high temperature was studied by finite element numerical simulation and experimental verification of the pin-on-disk model. Firstly, the geometrical model of the round bottom pin-on-disk contact was established. Then, the friction process was simulated by the Coulomb friction model. The ALE technique of ABAQUS was applied to move the contact nodes and update the grid. The finite element simulation of the ARCHARD wear model was realized. In order to deal with the increasing contact area, a simplify wear direction was proposed. Finally, the wear depth and volume was calculated and the wear law at 500 °C -900 °C was revealed. The results show that the wear process is gentle at the temperature of 500-700 °C, and the wear depth is within 0.08mm when the sliding distance reaches 1800m. When the temperature exceeds 800 °C, the wear rate increased sharply and the wear depth beyond 0.1mm, the FE result is consistent with the test results.
Effects of Extrusion-Shear and Direct Extrusion on the Plastic Deformation of AZ31 Magnesium Alloy
Authors: Hu Hong Jun , Sun Zhao , Zhang Ding Fei
Published: February 2018

Based on characteristics of direct extrusion for magnesium alloy seamless tube and continuous equal channel angular pressing (ECAP) of tubes, a new composite extrusion process of tubes including direct extrusion and many steps ECAP was invented firstly, which are shorten for TES process in this paper. A three-dimensional finite element thermo-mechanical coupled model and conditions for TES process were established. The extrusion process and cumulative strains evolution during TES process were simulated. The results show that TES process can improve the cumulative strains significantly. The microstructures observations of longitudinal sections for tubes fabricated by direct extrusion and TES process were carried out. It was found that when the extrusion temperature was 400°C, and extrusion ratio was 8.4 and the channel angle was 150°, TES process can refine the microstructures of tubes effectively.
Effects of Solid Solution and Aging Treatment on Texture Evolution and Properties of Cu-Ni-Si Alloy
Authors: Xu Zhi Jun , Chen Yin Li , Su Lan , Wei He , Liu Ze Sheng
Published: February 2018

The relationship between textures and properties of Cu-Ni-Si alloys was analyzed in this paper. The texture evolution of high strength and high elasticity Cu-Ni-Si alloy in different cold rolling and heat treatment processes was researched by the fiber analysis. And the electrical conductivity and tensile strength in different directions of the Cu-Ni-Si alloy were measured. The results showed that there were mainly Brass texture B{011}<211>，Gauss texture G {011}<100> and Copper texture C {211}<111> in the cold-rolled Cu-Ni-Si alloy. With the increase of cold deformation, the Copper texture was weakening, while the Gauss texture and Brass texture increased. When the deformation was 65%, there was almost no Copper texture in the alloy, and only Gauss and Brass texture exist. After the solid solution and aging process, both the Gauss and Brass texture were weakening, while the S texture {123}<624> increased greatly. After 4 hours aging the conductivity was up to 42.7% IACS. And the tensile strength of different directions is 745.5MPa (0°direction,RD), 684.5MPa (90°direction,TD) and 653.5MPa (45°direction) respectively. Based on the above results, maximum Schmid factor of different textures in different directions and the Index of Plane Anisotropy (IPA) were been analyzed.
Effect of Annealing Temperature on Microstructure and Properties of Ultra Purified Ferritic Stainless Steel Containing Copper
Authors: Yin Hong Xiang , Wu Yi , Zhao Ai Min , Zhao Zheng Zhi , Fu Qiu Qin
Published: February 2018

The effects of annealing temperature on microstructure, mechanical properties, formability, and texture evolution were analyzed in the article. The microstructure of the steel obtained through different annealing processes were investigated by means of transmission electron microscopy; The micro texture of steel was measured by using electron back scattering diffraction analysis; The relationship between Cu precipitates and matrix was analyzed by using the selected area diffraction technology. The results show that when annealing temperature was 700 ~ 850 °C, the yield strength and tensile strength first decreased slightly and then increased, while the elongation accordingly first increased then decreased slightly. The best mechanical property and formability were obtained at 800 °C. Cu precipitates reduced with the increase of annealing temperature and it accorded with K - S relationship with matrix. The grains near the {111} < 112 > orientation grew up selectively. The higher the temperature, the more the γ fiber texture content. But at higher temperature (850 °C), γ texture was damaged and the content was reduced.
Nondestructive Evaluation Method of Average Grain Size in TWIP Steel by Laser Ultrasonic
Authors: Zhang Yan Jie , Wang Xiao Chen , Yang Quan , Xue Ren Jie , Yin An Min
Published: February 2018

TWIP steel has the characteristics of high elongation and high tensile strength at room temperature, and therefore it is widely used in the automobile manufacturing industry. Since the grain size has a very important influence on its mechanical properties and corrosion resistance it is significant to study the average grain size of TWIP steel. In this experiment, the specimens were heated to 700~1000°C and preserved for one hour, and the recrystallized structures with different average grain sizes were obtained. All the samples were tested by laser ultrasonic experimental platform and the standard sample was selected. Then the attenuation coefficients of remaining samples were compared with the standard samples by conventional methods. The results showed that the larger the difference between the average grain size of the test sample and the standard sample is, the greater the error of the test will be. The new evaluation model was established by the improved method, and the prediction error was reduced to 5.44~11.61%, which proved the effectiveness of the new method. In addition, laser ultrasonic testing has the advantages of high efficiency and no damage compared with traditional methods.
Transfer Welding Process and Microstructure and Properties of Titanium/Steel Clad Pipe
Authors: Bi Zong Yue , Yang Jun
Published: February 2018

Titanium/steel clad material with excellent mechanical properties and corrosion resistance has important application in the oil, gas and ocean equipment. Due to the metallurgical incompatibility of titanium and steel, the mechanical properties of weld joint would completely lose when the brittle intermetallic phase existed in the fusion welding process. Therefore, the gas tungsten arced welding (TIG) + metal inert-gas welding (MIG) + metal active-gas welding (MAG) with pure vanadium and pure copper composite filler metals for welding connection experiment in this study was carried out on Ø610mm×(14+2)mm TA1/X65 titanium/steel clad pipe fitting (titanium cladding with thickness 2 mm, X65 pipeline steel with thickness 14 mm). The microstructure, interface element distribution, main phase, microhardness distribution on cross section and mechanical properties of butt welds were researched by using OM, XRD, EDS element mapping, microhardness and tensile tests. The result showed that the use of pure vanadium and pure copper composite filler metals for welding connection could effectively avoid the production of intermetallic compounds in the process of titanium/steel composite pipe fusion welding. The deposited metal of titanium, vanadium, copper and steel had obvious zoning, the inter-diffusion melting phenomenon was not severe, which is by using solid solution phases to transit zonings of deposited metal. The microstructure of titanium and vanadium transition interface were composed of titanium-based solid solution, the microstructure of vanadium and copper transition interface was composed of vanadium-based solid solution, and the microstructure of copper and steel transition interface were composed of copper-based solid solution. The transition interface had no porosity, crack and other defects. The tensile strength of the weld was 546MPa, which is mainly contributed by the carbon steel layer. With pure vanadium and pure copper as transition filler metal for the welding connection TA1/X65 clad pipe was successfully realized by TIG+MIG+MAG welding method, and the strength index reached the desired effect.
Hot Compression Deformation Behavior and Microstructural Evolution of Al-7.5Zn-1.5Mg-0.2Cu-0.2Zr Alloy
Authors: He Jian Liang , Zhang Da Tong , Zhang Wen , Qiu Cheng
Published: February 2018

Hot compression tests of as-homogenized Al-7.5Zn-1.5Mg-0.2Cu-0.2Zr alloy were carried out on Gleeble-3500 thermal simulation machine at the temperature ranging from 350°C to 550°C and strain rate ranging from 0.001s-1 to 10s-1. Processing maps were established on the basis of dynamic material model, and the microstructure was studied using electron back scattered diffraction (EBSD) technique. The results showed that the peak stress and steady flow stress decrease with decreasing strain rate or increasing deformation temperature. There are one peak efficiency domain and one flow instability domain in the processing maps. The flow instability domain which exists in high-strain-rate region becomes larger with increasing strain. Shear bands occur at 45° toward the compression axis at grain interiors and meanwhile flow localization occurs. The optimum deformation temperature and strain rate ranges from 450°C to 500°C and 0.003s-1 to 0.1s-1, respectively, with high power dissipation efficiency of 34-39%.
Effect of WC Additive on Microstructural Evolution and Properties of TiC Steel-Bonded Carbide
Authors: Li Hong Wei , Li Guo Ping , Guo Li Bo , Luo Feng Hua , Wang Xi Bin , Wang Si Tao
Published: February 2018

TiC base high manganese steel-bonded carbide was manufactured by powder metallurgy technique, and the effect of adding mode of WC additive on microstructural evolution and properties of the alloy was studied. SEM microstructure showed that surrounding structure appeared obviousely with WC additive; while microstructure of the alloy was well-distributed and particle shape was distinct very much. The shape of TiC particles became irregular with pure WC powder addition, and irregular with further increase of WC content, and the shape of some TiC particles became angular because of excessive reaction between TiC particles and WC additive. microstructure of the alloy was refiner and the strength, toughness were improved with the increase of WC addition. (Ti, W)C solid solution is superior to form on the surface of TiC particles through dissolution precipitation mechanism because the activity energy of WC was higher than that of TiC-WC compound carbides when WC was added in the alloy, and the particle shape of TiC became more irregular and the properties were improved significantly.
Preparation and Characterization of Mechanical Properties of Hydroxyapatite/Carbon Nanotube Laminated Ceramic Composites Consolidated by Spark Plasma Sintering
Authors: Meng Ye , Qiang Wen Jiang , Pang Jing Qin
Published: February 2018

Laminated xCNTs-HAP/yCNTs-HAP ceramic composites were consolidated using a spark plasma sintering(SPS) technique at SPS temperature 900°C, pressure 40MPa and holding time 5min. The effect of carbon nanotubes content and thickness of each layer on mechanical properties of the composites was investigated. It was demonstrated that the stratified structure improvedthe flexural strength obviously. All the flexural strength of laminar compositewashigher than that of single CNTs-HAP ceramic, up to 112.4MPa. Since the matrix of each layer wereHAP, the difference liesonly in the content of carbon nanotubes, thus avoiding the common problem of the interlayer bonding in other layered composites with different materials. In order to characterize the toughness of the layered composite, the stress-strain curve was compared showingthat the existence of the stratified structure improved the stress-strain obviously.
Machinability for C/SiC Composite Material by Electrical Discharge Machining
Authors: Zhang Yong Fu , Chen Wei Wei , Cheng Huan Wu , Zhang Yu Ping
Published: February 2018

A new method was adopted in this study to machine C/SiC composite. The machinability was studied by processing some shapes in the material in this way. Small deep holes were machined firstly to test whether the copper electrode was suitable enough to be adopted in the Electrical Discharge Machining. Then holes of different diameters were processed by two kinds of electrodes to study the more appropriate electrode material by comparing machining efficiency of two electrodes. Then complicated shapes were machined based on these conditions. Finally, a simulation model was built up to study the influence of the fluid on the electrode and the workpiece in the Fluent 6.3. According to the study, Electrical Discharge Machining Technology is suitable enough to machine the hard and brittle materials like C/SiC composite and the accuracy that the error should not exceed 0.5 mm can also be guaranteed well.
Microstructural Changes and Thermal Stability of A201, 319s and 2618 Aluminum Alloys during Thermal Exposure
Authors: Gao Jun Zhen , Zhu Qiang , Li Da Quan , Kang Yong Lin
Published: February 2018

Turbocharger compressor wheels are often made of 3XX cast aluminum alloys and forged 2618 alloy. These age hardening aluminum alloys have high strength-to-weight ratio at ambient temperature. However, the strength of the aluminum alloys decreases rapidly when applied at high temperatures, such as for turbochargers where application temperature can be above 200 °C. The major reason is that the fine precipitated phases coarsen rapidly tending to their equilibrium states. The thermal stability of the 319s-T61, A201-T71 and 2618-T6 alloys were compared in this paper. The three alloys were exposed at 200 °C for 100 h during heat treatment. Hardness, tensile tests and TEM were carried out to investigate the mechanical properties and microstructure variation of these three alloys. The results indicated that the A201 alloy exhibited the best thermal stability among the three alloys and 319s alloy is the weakest one. TEM observation showed that with the increase of the exposure time, the strengthening precipitates phase θ′ in A201/319s alloys and S′ in 2618 alloy coarsened and then transformed to stable θ phase and S phase, respectively, while the primary strengthening phase Ω in A201 remained stable, which may be contributed the higher thermal stability of A201 than 319s and 2618.
Interfacial Effect on Mechanical Properties of Polypropylene Ternary Nanocomposites
Authors: Wang Wei , Wang Wei , Lv Dong , Wu Jing Shen
Published: February 2018

The matrix/filler interface plays a vital role in mechanical properties of polypropylene (PP)/rigid nanoparticles composites. In general, the use of spherical stearic acid modified CaCO3 (SA-CaCO3) can induce a weak interfacewhich facilitatesparticle debonding from the matrix under loading and reduces plastic resistance, enhancing the toughness of nanocomposites, while the use of polymer-grafted nanoparticles (PGS) can improve the Young’s modulus and yield stress because of strong interfacial binding between particle and matrix. With the objective to simultaneously improve the modulus, yield stress and toughness, the ternary nanocomposites, PP/PGS/CaCO3 (PPSC), were prepared and the morphology, crystallization, and mechanical behavior were investigated and compared to their binary nanocomposites. The results show that Young’s modulus is enhanced as the particle loading, and the yield stress is balanced by two interactions, i.e. the decreasing effect of the weak interface and the enhancement effect of the strong interface. The impact strength of the ternary nanocomposites shows insignificant improvement compared with neat PP, which is attributed to the brittle effect of the weak interface in the particle cluster of SA-CaCO3 and PGS.
Structures, Mechanical Properties and Band Structures of Pentagonal BxNy Monolayers
Authors: Liu Li Zhao , Pang Qiao Tong , Liu Yang
Published: February 2018

Stable structures of pentagonal BxNymonolayers of different stoichiometric ratios were investigated through density functional theory calculations. Combining the energy and phonon dispersion, two stable pentagonal BxNystructures, B2N4‒I and B3N3‒I, are predicted. Under uniaxial and biaxial tensile strains, B2N4‒I and B3N3‒I show anisotropy mechanical behaviours in terms of Young’s modulus and intrinsic strength. B2N4‒I possesses larger Young’s modulus (up to 206 N/m) and intrinsic strength (up to 40 GPa) compared with those of B3N3‒I. Particularly, due to the low symmetry and prominent anisotropy, uniaxial tensile strain can uniquely tailor the band gap and trigger the transition from a direct to an indirect band gap in semiconducting B3N3‒I.
Stability, Mechanical Properties and Electronic Properties of X3Si (X=V, Nb, Cr, Mo and W) from First Principles Calculations
Authors: Wei He , Chen Yin Li , Su Lan
Published: February 2018

The transition metal silicide X3Si (X = V, Nb, Cr, Mo and W) was characterized by its low density, high melting point, high temperature hardness, high temperature resistance to wear, high temperature oxidation resistance and corrosion resistance in this paper. For the fields such as aerospace, gas turbine etc, with the application of a new generation of high temperature structural materials, transition metal silicide will be one of their candidate materials. The stability, crystal structure, mechanical properties, electronic properties, Debye temperature and hardness of X3Si(X=V, Nb, Cr, Mo and W) compounds were calculated employing electronic density functional theory (DFT) and the generalized gradient approximation (GGA). The results show that the remaining silicides have stable structures except that W3Si is a metastable structure in X3Si compounds. Based on the stress-strain theory, the bulk modulus, shear modulus, Young's modulus and Poisson's ratio of Cr3Si and Mo3Si were estimated by Voigt-Reuss-Hill method: 248.7 GPa, 158.9 GPa, 393.0 GPa, 0.24 and 249.2 GPa, 134.6 GPa, 342.1 GPa, 0.27. According to the state density (DOS) analysis, we can see that the valence band of X3Si compound is a combination of covalent bond and metal bond. The temperature of Debye of Cr3Si (645.1 K) in X3Si compound is the highest. The hardness of these silicon compounds is evaluated using a semi empirical hardness theory and the result shows that Cr3Si (10.96 GPa) is the hardest compound among them.
CBED and EELS Measurements of Post-Irradiated Aluminum Specimen Thickness
Authors: Jia Rong Guang , Zhang Chong Hong , Fu Xin , Ma Tong Da
Published: February 2018

CBED and EELS are most common methods to determine the thickness of the TEM specimen. In this work, specimen thickness of He-ion irradiated Al is measured respectively by CBED and EELS under 200kV. The helium concentration and the atomic displacement damage level are 2000appm and 0.2dpa, respectively. The CBED results show that the measurements of extinction distance match the calculations of effective extinction distance considering the deviation vector of the crystal. Moreover, it is proven by modeling analysis that He-ion irradiation does not affect the thickness measurements of extinction distance. Compared with CBED, the specimen thickness, measured by EELS, is larger, and may be attributed to the decrease of the zero-loss peak due to a part of elastic scattering electronsloss and the larger inelastic scattering mean free path selected. The EELS measurement error is less than 20%,consistent with the accuracy (about 20%) byK. Iakoubovskiiet al.
Trace Al-Ti-C-Ce on Solidification Structure Transformation and Fracture Properties of Al-Cu-Mn Alloy
Authors: Guo Ting Biao , Wang Chen , Li Qi , Zhang Feng , Ding Wan Wu
Published: February 2018

As a kind of refining agent, Al-Ti-C-Ce intermediate alloy is widely used in the field of nonferrous alloy smelting. The effect of Al-Ti-C-Ce contents on microstructure and properties of Al-Cu-Mn alloy was studied by OM, SEM, EDS and other test methods. The results show that the as-cast microstructure of Al-Cu-Mn alloy is obviously refined after adding 0.1% Al-Ti-C-Ce, and the θ phase is characterized with the shape of point or strip. With the increase of the addition amounts, parts of the grains coarsened. When the addition amount reached to 0.3%, the refinement effect of the alloy microstructure was further reduced, and the number of intergranular precipitates TiC and Al3Ti increased. Ductile fracture is the main failure mode of the alloy. After T6 heat treatment, the grain size changed little, and the number of θ phase, TiC and Al3Ti decreased, changed from the mesh to the point or needle or strip structure, and the proportion of alloy ductile fracture increased. The addition of Al-Ti-C-Ce has positive effect on improving the microstructure and properties of Al-Cu-Mn alloy.
Preparation and Sorption Properties of Zr-Co-Ce Getter Films
Authors: Wu Hua Ting , Cui Jian Dong , Xu Yao Hua , Xu Xiao Qiang
Published: February 2018

In order to further study the relationship between sorption properties of ZrCoCe thin films and magnetron sputtering process parameters, ZrCoCe getter films were deposited on the Si(100) substrate by DC magnetron sputtering. In this paper, background vacuum, sputtering pressure and sputtering power as experimental variables were discussed in detail. The surface and cross section microstructure and phase of the film were determined by scanning electron microscopy (SEM) and H2 sorption measurement of films was carried out by a dynamic sorption method. It is demonstrated that porous columnar structure film can be achieved under the conditions of the background degree less than 5.0×10-4 Pa, sputtering pressure is 4 Pa and sputtering power is 120 W. As a result of the optimization of the porous columnar structure, the sorption properties of the films are also improved.
Phase Transition Behavior and Magnetocaloric Effect in a Heusler Ni50Mn37Sn13 Unidirectional Crystal
Authors: Fang Yue , Dai Yu Ting , Xu Zhi Shuai , Zheng Hong Xing
Published: February 2018

A unidireon heating, followed with a ferromagnetic- paramagnetic transition in austenite for the produced unidirectional crystal. Under a magnetic field change of 3 T, the total effective refrigeration capacity was strikingly enhanced up to 125 J/kg, nearly 64% higher than that of polycrystalline master alloy ctional crystal of Heusler Ni50Mn37Sn13 material was produced using a modified high-pressure optical zone-melting furnace. A structural transformation between weak-magnetization martensite and ferromagnetic austenite occurred first up(76 J/kg). The modified high-pressure optical zone-melting technique demonstrated high potentials for the fabrication of super-performance Heusler Ni-Mn-based magnetocaloric materials.
Graphene-Carbon Nanotubes-Modified LiFePO4 Cathode Materials for High-Performance Lithium-Ion Batteries
Authors: Chen Yu Ting , Zhang Hai Yan , Chen Yi Ming , Qin Gai , Lei Xing Ling , Liu Li Ying
Published: February 2018

A nanocrystalline LiFePO4/graphene-carbon nanotubes (LFP-G-CNT) composite has been successfully synthesized by a hydrothermal method followed by heat-treatment. The microstructure and morphology of the LFP-G-CNTs composite were comparatively investigated with LiFePO4/graphene (LFP-G) and LiFePO4/carbon nanotubes (LFP-CNT) by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The LFP-G-CNTs nanoparticles were wrapped homogeneously and loosely within a 3D conducting network of graphene-carbon nanotubes. The conducting networks provided highly conductive pathways for electron transfer during the intercalation/deintercalation process, facilitated electron migration throughout the secondary particles, accelerated the penetration of the liquid electrolyte into the LFP-G-CNT composite in all directions and enhanced the diffusion of Li ions. The results indicate that the electrochemical activity of LFP-G-CNT composite may be enhanced significantly. The charge-discharge curves, cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS) results demonstrate that LFP-G-CNT composite performes better than LFP-G and LFP-CNT composites. In particular, LFP-G-CNT composite with a low content of graphene and carbon nanotubes exhibites a high initial discharge capacity of 168.4 mAh g−1 at 0.1 C and 103.7 mAh g−1 at 40 C and an excellent cycling stability.
A Charge Storage Based Enhancement Mode AlGaN/GaN High Electron Mobility Transistor
Authors: Wang Hui , Jiang Ling Li , Wang Ning , Yu Hong Yu , Lin Xin Peng
Published: February 2018

In this work, a charge storage based enhancement mode (E-mode) AlGaN/GaN high electron mobility transistor (HEMT) is proposed and studied. A stacked gate dielectrics, consisting of a tunnel oxide, a charge trap layer and a blocking oxide are applied in the HEMT structure. The E-mode can be realized by negative charge storage within the charge trap layer during the programming process. The impact of the programming condition and the thickness of the dielectrics on the threshold voltage (Vth) are simulated systematically. It is found that the Vth increases with the increasing programming voltage and time due to the increase of the storage charge. Under proper programming condition, the Vth can be increased to more than 2 V. Moreover, It is also found that the Vth increases with the decrease of the thickness of the dielectrics. In addition, it is found that the breakdown voltage of such HEMT can be adjusted by varying the gate dielectric stacks.
Structure and Microwave Absorption Properties of Ho-Fe-Si Alloys
Authors: Luo Jia Liang , Pan Shun Kang , Cheng Li Chun , Lin Pei Hao , He Yu , Chang Jun Qing
Published: February 2018

The Ho2Fe17-xSix (x=0.0, 0.1, 0.2, 0.3) alloys were prepared by arc melting and high energy ball milling method. The influence of the Si substitution on phase structure, morphology and electromagnetic parameters were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and vector network analyzer (VNA), respectively. The results show that the Ho-Fe-Si particles are flaky after the ball milling. The minimum absorption peak frequency shifts towards a lower frequency region with the increasing of Si content. The minimum RL of Ho2Fe16.7Si0.3 reaches-42.96 dB at 9.76 GHz, and the frequency bandwidth of R<-10 dB reaches about 2.64 GHz with the best matching condition d=1.6 mm. The reflection loss with the thickness ranging of 1.2-3.0 mm could reach-10 dB, which indicates the particles be considered as the promising microwave absorbing materials with a good absorption properties.
The Solvatochromic Materials: A Progress Review
Authors: He Jian , Chen Jian Sheng
Published: February 2018

Solvatochromic compounds attracted more and more attentions in the application of fluorescent probe, indicator, chromogenic reagent, molecular recognition field and so on. Although sovatochromic effects have been discovered for more than a century, they are still difficult to understand and even more difficult to predict. This review introduced organometallic complexes and organic compounds of solvatochromic materials and highlight the latest progress in recent years, and the molecular structure design and solvatochromic properties are discussed.
Co-Precipitation Synthesis and Photoluminescence Properties of Sc0.88Lu0.05(V1-xPx)O4:Eu3+0.07 Red Phosphor for White Light Emitting Diodes
Authors: Wu Di , Ye Xin Yu , Yang Xin Hua , Liu Fan , Zhao Jian Wen , Yang Fan
Published: February 2018

Sc0.88Lu0.05(V1-xPx)O4:Eu3+0.07(0≤x≤0.5) phosphors were synthesized by co-precipitation method. The structure, morphology and luminescence spectra of samples were investigated by XRD, SEM and fluorescence spectrophotometer, respectively. The samples doped with Eu3+, Lu3+and PO43-can maintain the body-centered tetragonal structure of ScVO4and the morphology essentially remains unchanged with slight agglomeration. The excitation spectrum intensity of Sc0.88Lu0.05(V1-xPx)O4:Eu3+0.07increase within the near UV excitation (360-410nm). The optimum doping concentration of PO43-is 0.2(x value), and the maximum emission intensity of Sc0.88Lu0.05(V0.8P0.2)O4:Eu3+0.07is about 35 % higher than the Sc0.88Lu0.05VO4:Eu3+0.07under 365 nm excitation. Decay curve of5D0state for as-prepared samples fits the single order exponential behavior, the lifetime of5D0increase first and then decrease with the increase of PO43-doping concentration. The internal quantum efficiency is up to 66.73% under 365nm excitation, When the temperature rises to 200°C, the emission intensity maintains 79.3% of that in the room temperature. Sc0.88Lu0.05(V0.8P0.2)O4:Eu3+0.07phosphor shows high internal quantum efficiency and thermal stability, which is suitable for the UV-pumped white LED as red phosphor.
A Narrative Analysis: Examining the Transition to Practice for the Full-Time Secondary School Athletic Trainer
Authors: Mazerolle Stephanie M. , Kirby Jessica , Walker Stacy E.
Published: February 2018

Context: 

The transition to clinical practice is an important topic in athletic training because it is viewed as a stressful time that is accompanied by self-doubt. Mentorship and previous experience support the transition to practice, but little information is available on the organizational entry of the athletic trainer (AT) who is employed full time in the secondary school setting.

Objective: 

To understand the experiences of newly credentialed ATs in full-time positions in the secondary school setting.

Design: 

Qualitative study.

Setting: 

Secondary schools.

Patients or Other Participants: 

Seventeen ATs (4 men, 13 women; age = 25 ± 4 years) were employed full time in the secondary school setting. On average, the full-time ATs worked 40 ± 10 hours per week.

Data Collection and Analysis: 

All participants completed a semistructured telephone interview with 1 researcher. Data were analyzed using a narrative analysis, and credibility was established by peer review and researcher triangulation. The narrative research paradigm guided our protocol and supported the rigor of the study.

Results: 

Our analyses revealed that transition to practice was organic, such that the newly credentialed AT gained awareness by engaging in the role daily. Additionally, the transition process was facilitated by previous experience in the setting, mostly from educational training. Ongoing communication with various stakeholders (athletic directors, team physicians, and peer ATs) in the setting also assisted in the process of transitioning. Finally, mentorship from previous preceptors provided support during the transition process.

Conclusions: 

Transitioning into full-time clinical practice in the secondary school setting was informal and supported by professional relationships and past experiences. Past experiences allowed for awareness but also the development of mentoring relationships that continued beyond the clinical education experience. Communication also assisted the newly credentialed AT, as it provided feedback for legitimation by multiple stakeholders.
Comparative analysis of inflammatory gene expression levels in metabolic syndrome & coronary artery disease
Authors: Nair Jiny , Kakkar Vijay V. , Shanker Jayashree
Published: February 2018

Background & objectives:

Metabolic syndrome (MetS) increases the likelihood of developing coronary artery disease (CAD), and inflammation is involved in the pathogenesis of both these conditions. The present work was conducted to examine the relative expression of 18 key inflammatory genes associated with MetS and incident CAD in a representative group of patients.

Methods:

A total of 178 male patients, including 57 with CAD and 121 without CAD, were enrolled in the study. The participants without CAD were characterized for the presence of MetS using modified criteria specific for Asian Indians, which included a lower cut-off for waist circumference (≥90 cm for men). The expression of 18 inflammatory genes was evaluated in peripheral whole blood by quantitative polymerase chain reaction method.

Results:

Of the 121 participants without CAD, 53 (43.8%) had three or more risk factors (MetS group), 50 (41.3%) had one or two risk factors (non-MetS group), while 18 (14.8%) did not have any risk factors (control group). High nuclear factor-kappa B (NF-κB) expression levels and low interleukin-10 (IL-10) levels were observed in MetS patients. Linear association was seen between NF-κB and vascular endothelial growth factor A (VEGFA) expression and with increase in MetS components. Comparison of gene expression pattern between CAD and MetS revealed significantly higher expression of leukotriene genes - arachidonate 5-lipoxygenase (ALOX5), arachidonate 5-lipoxygenase activating protein (ALOX5 AP), leukotriene A4 hydrolase (LTA4H) and leukotriene C4 synthase (LTC4S), and lower expression of NF-κB, interleukin 1 beta (IL-1β), monocyte chemoattractant protein-1 (MCP-1/CCL2) and signal transducer and activator of transcription 3 (STAT3) genes in CAD. There was linear increase in expression of LTA4H, LTC4S, IL-8 and VEGFA genes across the four groups, namely from controls, non-MetS, MetS and CAD.

Interpretation & conclusions:

A distinct gene expression pattern was seen in MetS and CAD implying a well-orchestrated inflammatory and immune activity. Specifically, NF-κB might be playing an active role in MetS, allowing further expansion of the inflammatory process with resolution of inflammation in full-blown CAD, wherein other gene players such as leukotrienes may dominate.
Occurrence, patterns & predictors of hypogonadism in patients with HIV infection in India
Authors: Dutta Deep , Sharma Lokesh Kumar , Sharma Neera , Gadpayle Adesh K , Anand Atul , Gaurav Kumar , Gupta Ankit , Poondla Yashwanth , Kulshreshtha Bindu
Published: February 2018

Background & objectives:

Data on hypogonadism among human immunodeficiency virus (HIV)-infected Indians are not available. This study was aimed to evaluate the occurrence, pattern and predictors of hypogonadism in HIV-infected Indians.

Methods:

Consecutive stable HIV-infected patients, 18-70 yr age, without any severe comorbid state, having at least one year follow up data at the antiretroviral therapy clinic, underwent clinical assessment and hormone assays.

Results:

From initially screened 527 patients, 359 patients (225 males; 134 females), having disease duration of 61.44±39.42 months, 88.58 per cent on highly active antiretroviral therapy (HAART), 40.67 per cent having tuberculosis history and 89.69 per cent with vitamin D insufficiency were analyzed. Testosterone <300 ng/dl was documented in 39.11 per cent males. Primary, hypogonadotropic hypogonadism (HypoH) and compensated hypogonadism were observed in 7.56, 31.56 and 12.44 per cent males, respectively. Males with hypogonadism were significantly older (P=0.009), and had higher opportunistic infections (P<0.001) with longer disease duration (P=0.05). Menstrual abnormalities were observed in 40.3 per cent females, who were significantly older (P<0.001), had lower CD4 count (P=0.038) and higher tuberculosis history (P=0.005). Nearly 46.3, 16.2 and 13 per cent women with menstrual abnormalities were in peri-/post-menopausal state, premature ovarian insufficiency (POI) and HypoH, respectively. Age, CD4 count at diagnosis and 25(OH)D were best predictors of male hypogonadism. Age and CD4 count increment in first 6-12 months following HAART were the best predictors of POI.

Interpretation & conclusions:

Hypogonadism was observed to be a significant problem in HIV-infected men and women in India, affecting 39 and 29 per cent patients, respectively. HypoH was the most common form in males whereas ovarian failure being the most common cause in females.