英语教学文化背景知识学习和渗透的对策研究

经济全球化背景下,各国之间的交流合作越来越频繁,我国对专业英语人才提出了更高的要求。在英语教学中,不仅要传授学生英语知识,提高学生应用英语的能力,而且要重视社会文化背景知识的学习和渗透,提高学生的跨文化交际能力,为学生以后的发展奠定坚实的基础。英语教学中,教师要根据教学内容,巧妙的渗透文化背景知识,提高教学质量。本文分析了当前英语教学中文化背景知识的渗透现状,探析有效的渗透策略。

Bending properties and fracture mechanism of C/C composites with high density preform

C/C composites with banded structure pyrocarbon were fabricated by fast chemical vapor infiltration（CVI）,with C3H6 as carbon source,N2 as carrier gas,and three-dimensional（3D） 12K PAN-based carbon fabric with high density of 0.94 g/cm3 as preform.Experimental results indicated that the fracture characteristics of C/C composites were closely related to the frequency of high-temperature treatment（HTT） at the break of CVI process.According to the load？displacement curves,C/C composites showed a pseudoplastic fracture after twice of HTT.After three times of HTT,load？displacement curves tended to be stable with a decreasing bending strength at 177.5 MPa.Delamination failure and intrastratal fiber fracture were observed at the cross-section of C/C composites by scanning electronic microscope.Because the content of pyrocarbon and fibers has a different distribution in layers,the C/C composites show different fracture characteristics at various regions,which leads to good toughness and bending strength.

Wear behavior of SiC/PyC composite materials prepared by electromagnetic-field-assisted CVI

Silicon carbide/pyrolytic carbon (SiC/PyC) composite materials with excellent performance of self-lubrication and wear resistance were prepared on SiC substrates by electromagnetic-field-assisted chemical vapor infiltration (CVI). The composition and microstructure of the SiC/PyC materials were investigated in detail by XRD, SEM and EDS, etc. The effects of the deposition temperature on the section features and wear resistance of the SiC/PyC were studied. The results show that the PyC layers were deposited onto SiC substrates spontaneously at a lower deposition temperature. The SiC substrates deposited with PyC can significantly reduce the wear rate of the self-dual composite materials under dry sliding condition. The wear tests suggest that the SiC/PyC composite materials own a better wear resistance property when the deposition temperature is 800 °C, and the wear rate is about 64.6% of that without the deposition of PyC.

Preparation of TiO2/Bi2O3 Microfibers and Their Photocatalytic Activity

A series of TiO2/Bi2O3 heterojunction microfibers have been fabricated using cotton fibers as bio-templates, and characterized by XRD, SEM and UV-Vis techniques. Results reveal that Bi2O3 in the TiO2/Bi2O3 sample is assigned to monoclinic and tetragonal mix-crystal phase. Fibers lengths can reach several micrometers and diameters range from 0.5 μm to 3 μm. Compared with pure TiO2 and Bi2O3, TiO2/Bi2O3 samples display better absorption in visible light region. Photocatalytic activity was evaluated by degradation of MB under visible light irradiation. TiO2/Bi2O3 microfibers exhibite much higher activity than pure TiO2 and Bi2O3, and 22.84%TiO2/Bi2O3 can achieve the decomposition of about 95%MB, which is attributed to synergistic effects of the strong visible-light absorption of TiO2/Bi2O3 microfibers and the heterojunction formed between TiO2 and Bi2O3.

Effect of Molybdenum Doping on Oxygen Permeation Properties and Chemical Stability of SrCo0.8Fe0.2O3-δ

The phase composition, microstructure, thermal expansion coefficients, oxygen permeation properties and chemical stability of SrCo0.8Fe0.2O3-δ （SCFM） were investigated and compared with those of SrCo0.8Fe0.2O3-δ（SCF）. Single phase SCFM was successfully prepared by a combined EDTA-citric method. SCFM shows a lower thermal expansion coefficient （24× 10^-6-29× 10^-6/K） than SCF between 500 and 1050 ℃, indicating a more stable structure. SCFM shows a high oxygen permeation flux, although the oxygen flux of SCFM decreases slightly because of Mo dopant. Furthermore, it was demonstrated that the doping of Mo in SCF can prevent the order-disorder transition and improves the chemical stability to CO2.

Effects of dip-coated BN interphase on mechanical properties of SiC_f/SiC composites prepared by CVI process

BN interphase was successfully synthesized on SiC fiber fabrics by dip-coating process using boric acid and urea as precursors under N2 atmosphere. The morphology of BN interphase was observed by SEM, and the structure was characterized by XRD and FT-IR spectra. The SiCf/SiC composites with dip-coated BN interphase were fabricated by chemical vapor infiltration （CVI） process, and the effects ofBN interphase on the mechanical properties of composites were investigated. The results show that the SiC fibers are fully covered by BN interphase with smooth surface and turbostratic structure （t-BN）, and the thickness is about 0.4 μm. The flexural strengths of SiCf/SiC composites with and without BN interphase are about 180 and 95 MPa, respectively. Compared with the as-received SiCf/SiC composites, the composites with BN interphase exhibit an obvious toughened fracture behavior. From the microstructural analysis, it can be confirmed that the BN interphase plays a key part in protecting the fibers from chemical attack during matrix infiltration and weakening interfacial bonding, which can improve the mechanical properties of SiCf/SiC composites remarkably.

Experimental investigation on deformation characteristics and permeability evolution of rock under confining pressure unloading conditions

Deformation behavior and hydraulic properties of rock are the two main factors that influence safety of excavation and use of rock engineering due to in situ stress release.The primary objective of this study is to explore deformation characteristics and permeability properties and provide some parameters to character the rock under unloading conditions.A series of triaxial tests with permeability and acoustic emission signal measurement were conducted under the path of confining pressure unloading prior to the peak stress.Deformation behavior and permeability evolution in the whole stress–strain process based on these experimental results were analyzed in detail.Results demonstrate that,under the confining pressure unloading conditions,a good correspondence relationship among the stress–axial strain curve,permeability–axial strain curve and acoustic emission activity pattern was obtained.After the confining pressure was unloaded,the radial strain grew much faster than the axial strain,which induced the volumetric strain growing rapidly.All failures under confining pressure unloading conditions featured brittle shear failure with a single macro shear rupture surface.With the decrease in deformation modulus during the confining pressure unloading process,the damage variable gradually increases,indicating that confining pressure unloading was a process of damage accumulation and strength degradation.From the entire loading and unloading process,there was a certain positive correlation between the permeability and volumetric strain.

Microstructure and frictional properties of 3D needled C/SiC brake materials modified with graphite

The 3D needled C/SiC brake materials modified with graphite were prepared by a combined process of the chemical vapor infiltration,slurry infiltration and liquid silicon infiltration process.The microstructure and frictional properties of the brake materials were investigated.The density and open porosity of the materials as-received were about(2.1±0.1)g/cm3and(5±1)%,respectively.The brake materials were composed of 59%C,39%SiC,and 2%Si(mass fraction).The content of Si in the C/SiC brake materials modified with graphite was far less than that in the C/SiC brake materials without being modified with graphite,and the Si was dispersed.The braking curve of the 3D needled C/SiC modified with graphite was smooth,which can ensure the smooth and comfortable braking.The frictional properties under wet condition of the 3D needled C/SiC modified with graphite showed no fading.And the linear wear rate of the C/SiC modified with graphite was lower than that of the C/SiC unmodified.

Effect of nanofibers at surface of carbon fibers on microstructure of carbon/carbon composites during chemical vapor infiltration

Before densification by chemical vapor infiltration,carbon or SiC nanofibers were grown on the surface of carbon fibers by catalytic chemical vapor deposition using electroplated Ni as catalyst.The modification and mechanism of nanofibers on the pyrocarbon deposition during chemical vapor infiltration were investigated.The results show that the nanofibers improve the surface activity of the carbon fibers and become active nucleation centers during chemical vapor infiltration.They can induce the ordered deposition of pyrocarbon and adjust the interface bonding between pyrocarbon and carbon fibers during the infiltration.

In-situ preparation, modulation and mechanism of refractory metal carbide gradient coating

TiC, ZrC and TaC modified layers were in-situ prepared on graphite matrix by chemical vapor infiltration method with metal salts as the activator. Taking the TiC modified layer as an example, through thermodynamic calculation and experiment, the thermal decomposition process of raw materials(Ti/K_(2)TiF_(6)) was analyzed, the formation mechanism of TiC was determined, and the distribution of TiC modified layer was modulated. The results show that activator K_(2)TiF_(6)has higher decomposition temperature than NH4Cl, which is conducive to improving the utilization rate of raw materials in the gas infiltration process. Increasing the content of Ti powder can increase the concentration of reaction gas and contribute to the formation of TiC modified layer. When the molar ratio of Ti to K_(2)TiF_(6)is 3:1, the surface thickness and infiltration depth of Ti C are 5.42 and 136.24 μm, respectively. Increasing the reaction temperature can improve the rate of in-situ reaction and the thickness of TiC surface layer. When the experimental temperature rises to 1600 °C, the TiC surface layer thickness increases to 20.27 μm.

Effects of Chemical Osmotic Pretreatment on Drying Characteristics and Quality of Blueberry under Hot Air Drying

In order to study the effects of chemical osmotic pretreatment on the characteristics and quality of blueberry under hot air drying,fresh blueberries were pretreated with 2.5 g/100 mL K2CO3+0.6 g/100 mL olive oil,and 5.0 g/100 mL K2CO3+0.6 g/100 mL olive oil at(45±0.5)℃,respectively.The changes of water content,rehydration,hardness,microstructure,color difference,active ingredient anthocyanin,total phenol and DPPH radical scavenging capacity of dried blueberries in different treatment groups under hot air drying were compared and analyzed.The results showed that the dehydration rates of blueberries vary greatly according to the type of pretreatments when the samples were dried to the same water content with hot air.Specifically,the dehydration rate of dried blueberries pretreated by 5.0%K2CO3 solution was the highest,followed by 2.5%K2CO3 osmotic pretreatment and lastly the control group;the corresponding dehydration time was 10,14 and 20h,respectively.The physical qualities of dried blueberries,involving the browning degree,color difference,rehydration and microstructure,were significantly different between the chemical osmotic pretreatment group and the control group(P<0.05).The chemical osmotic pretreatment of K2CO3 solution increased the dehydration rate of the samples,shortened the drying time and maintained the quality of blueberries dried with hot air.There was no significant difference between the physical quality of dried blueberries pretreated by 2.5%and 5.0%K2CO3 solution(P>0.05),whereas there was significant difference in drying time and nutrient quality which is characterized by total phenols,anthocyanins,DPPH radical scavenging rate,soluble total sugar(P<0.05).Conclusion:5.0%K2CO3 osmotic pretreatment combining with hot air drying can improve the dehydration rate,shorten the drying time and maintain the physical and nutritional quality.

CMAS corrosion resistance characteristics of RE_(50)Ta_(x)Zr_(50-x)O_(175+0.5x)thermal barrier oxides in RE_(2)Zr_(2)O_(7)-RETaO_(4)systems

The corrosion resistance characteristics of RE-rich RE_(50)Ta_(x)Zr_(50-x)O_(175+0.5x)oxides in RE_(2)Zr_(2)O_(7)-RETaO_(4)systems to calcium-magnesium-alumino-silicate(CMAS)at 1300°C,and the influence of RE^(3+)and Ta^(5+)on chemical reactions and reactive crystallization of CMAS melts were investigated.The results show that following the thermochemical reactions,apatite,pyrochlore,reprecipitated fluorite and residual Yb(Y)TaO4phases were the predominant reaction products.Formation abilities of apatite and pyrochlore were found to be proportional to the ionic radius of RE^(3+).The increase of Ta^(5+)amount can decrease the number of available RE^(3+)to form apatite.Moreover,the resistance characteristic to CMAS corrosion in RE_(50)Ta_(x)Zr_(50-x)O_(175+0.5x)systems was decided by the combined action of apatite and pyrochlore phases.The cohesive mixture of apatite and pyrochlore phases can generate a dense layer near the reaction front,which had a positive effect on suppressing CMAS infiltration.The ability of the fluorite+RETaO4two-phase field was determined to be sufficient to mitigate CMAS corrosion.

Sodium alginate-polyvinyl alcohol/polysulfone (SA-PVA/PSF) hollow fiber composite pervaporation membrane for dehydration of ethanol-water solution

Using polysulfone （PSF） hollow fiber ultrafiltration membranes as the substrate, sodium alginate （SA） and polyvinyl alcohol （PVA） blend solutions as the coating solution, and maleic anhydride （MAC） as the cross-linked agent, SAPVA/PSF hollow fiber composite membranes were prepared for the dehydration of ethanol-water. The effects of different sodium alginate concentration in the coating solutions and different operating temperatures on pervaporation performance were investigated. The experimental results showed that pervaporation performance of the SA-PVA/PSF composite membranes for ethanol-water solution exhibited a high separation factor although they had a relatively low permeation flux. As SA concentration in SA-PVA coating solution was 66.7% and the operating temperature was 40 ℃, SA-PVA/PSF hollow fiber composite membrane （PS4） had a separation factor of 886 and flux of 12.6 g/（m^2·h）. Besides, SA-PVA/PSF hollow fiber composite membranes （PS3 and PS4） were used for the investigation of the effect of ethanol concentration in the feed solution on pervaporation performance.

Nanometallocarbosilanes： Synthesis, Physicochemical Properties and Structure

Highly efficient synthesis methods have been developed and characteristics of nanometallocarbosilanes molecular structure were studied by the research team of GNIIChTEOS （State Research Institute for Chemistry and Technology of Organoelement Compounds）. Nanometallocarbosilanes were synthesized by thermal co-condensation of oligocarbosilanes and alkyl amides of refractory metals. Initial, intermediate and final products of side reactions were characterized by 1H, 13C, 29Si NMR （nuclear magnetic resonance）, IR （infra-red） spectroscopy, GPC （gel-penetrating chromatography）, TGA （thermal gravimetric analysis）, TEM （transmission electron microscopy）, SEM （scanning electron microscopy）, RES （X-ray phase analysis） and elemental analysis. The proposed synthesis method of nanometallocarbosilanes was lbund to produce fusable soluble organosilicon oligomers with homogeneous distribution of nanoscale （10-20 nm） metal particles in the oligomer matrix. A computational model of the group and elemental composition of nanometallocarbosilanes was developed; it was shown that they are molecular globules of near-spherical shape and rigid polycyclic structure. Thermochemical treatment of nanometallocarbosilanes leads to SiC-nanoceramics （a high yield of up to 75-80 mass%） modified by metal nanoparticles （20-30 nm） contributing to its stabilization. The application of preceramic oxygen-free nanometallocarbosilanes will make it possible to advance in solving the problem of ceramic composite materials with long-term resistance at temperatures above 1,500 ℃ in oxidizing environments.

On the appreciation of the beauty and the permeation of the cultural factors in the teaching of the folk songs in Shanxi

In the teaching of the folk songs in Shanxi, the effective ＂permeation＂ has an important significance to the appreciation of the beauty behind the folk songs and the explanation and revelation of the cultural factors, the teaching effect of the folk songs in the local universities in Shanxi and the inheritance and development of the actual results of the folk songs in Shauxi. In this paper, combined with the teaching practice, the author intends to explore the necessity of the appreciation of the beauty and the permeation of the cultural factors in the teaching of the folk songs in Shanxi and the related pitching-in angle and the operational approaches.

The intercultural awareness in Korean Teaching

Language is the carrier of culture. We should not only focus on skills in teaching Korean culture, but also conduct a comprehensive analysis and guidance to penetrate culture and education of Korea in the teaching process. Which enhance the overall level. This thesis analyze and elaborate the characteristics of Korean teaching intercultural education. What＇ s more, it will propose corresponding solutions in penetration problems of culture and education for the Korean teaching.

Geochemical characteristics of reservoir after water and polymer flooding in Xingshugang oilfield of Daqing

Collecting 44 oil-sand specimens of Pu-I Member in two inspection wells before and after polymer flooding in the thirteenth district of Xingshugang oilfield,with experimental analysis,the author obtained the data about oil viscosity,flow,oil saturation and oil displacement efficiency.The result shows that viscous oil predominates in the main remaining oil in Xingshugang oilfield after water flooding with a certain amount of low viscosity oil,high viscosity oil and heavy oil;after polymer flooding,the viscous oil is main ingredient.Compared with water flooding,the low mobility and poor oil can be spread by polymer flooding,expanding the affected area and improving sweep efficiency and oil recovery.The geochemical affecting factors of water flooding and oil displacement efficiency refer to reservoir flow,permeability and the viscosity of residual oil.In the reservoir with permeability from low to high,the polymer flooding efficiency is better than water flooding.It provides the basis for improving the water and polymer flooding efficiency of the Xingshugang oilfield.

三维针刺C/SiC刹车材料的热物理性能

通过化学气相渗透(CVI)法结合反应熔体浸渗(RMI)法制备了三维针刺C/SiC刹车材料,系统研究了三维针刺C/SiC刹车材料的热物理性能。结果表明:C/SiC刹车材料的热膨胀系数随温度升高总体呈增大趋势,但呈规律性波动;在相同温度下,垂直于摩擦面方向的热膨胀系数远大于平行方向的。从室温至1300℃,平行和垂直于摩擦面方向的平均热膨胀系数分别为1.75×10-6K-1和4.41×10-6K-1;C/SiC刹车材料的比定压热容随温度的升高而增大,但增大速率逐渐减小。温度从100℃升到1400℃,其比定压热容从1.41 J/(g.K)增大到1.92 J/(g.K);C/SiC刹车材料的热扩散率随温度的升高而降低,并趋于常量。平行于摩擦面方向的热扩散率明显大于垂直于摩擦面方向的热扩散率。

Complex Permittivity and Microwave Absorbing Property of Si_3N_4-SiC Composite Ceramic

Si3N4-SiC composite ceramics were fabricated by chemical vapor infiltration using porous Si3Na ceramic as preform. The average grain size of SiC was 30 nm. Relationship between SiC content and relative complex permittivity of Si3Na-SiC within the frequency range of 8.2-12.4 GHz （X-band） was investigated. The average real part of relative complex permittivity ε′ of Si3N4-SiC increased from 3.7 to 14.9 and the relative imaginary part ε″ increased from 0.017 to 13.4 when the content of SiC increased from 0 to 10 vol.%. The Si3N4-SiC ceramic with 3 vol.% SiC achieved a reflection loss below -10 dB （90% absorption） at 8.0-11.4 GHz, and the minimum value was -27.1 dB at 9.8 GHz when the sample thickness was 2.5 mm. The excellent microwave absorbing abilities of Si3N4-SiC ceramic were attributed to the interfacial polarization at interface between Si3N4 and SiC and at grain boundary between SiC nanocrystals.