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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 324-325 (Nov. 2006), p. 879-882 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The effect of undissolved ferrite amount on bending fatigue properties and failuremechanism were studied by using 42CrMo steel with subcritical quenching process The amount ofundissolved ferrite were 0%, 10% and 15%, respectively. The hardness of the specimen was treatedto medium hardness. The experimental results show that the existence of undissolved ferrite can notonly change the microstructure, but also increase the bending fatigue life. The bending fatigue lifeelongates with increasing of amounts of undissolved ferrite. The grains can be fined by usingsubcritical quenching process and the area of phase boundaries can also be greatly increasedbecause of undissolved spheroidal carbide. The martensite and carbide can also be changed usingsubcritical quenching process. Stress relaxation due to the move of dislocations inside the ferriteand the promotion of strength due to occurring of plastic deformation and enwinded dislocations aremain reasons of improving the bending fatigue life. The bending fatigue life elongates with theincrease of amounts of undissolved ferrite before the amount of undissolved ferrite reaches 10%.Under the experiment conditions, when the amount of undissolved ferrite is 10%, the bendingfatigue life will be the longest
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 477-480 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The effect of heat treatment on mechanical prosperities of Mg65Cu25Gd10 glass has beenstudied in this paper. The thermal stability and the structure of as-spun and heat treated Mg65Cu25Gd10alloys were examined by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD).The compression tests were performed using a computer controlled tensile test machine. ExtendedX-ray absorption fine structure (EXAFS) was applied to study the structural changes ofMg65Cu25Gd10 glass during annealing. Results showed that the decline of mechanical properties forMg65Cu25Gd10 glass after annealing was closely related to the changes in local environment of Cuatoms and appearance of crystalline phases, and not the Gd local structure
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 575-578 (Apr. 2008), p. 639-642 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper, the reliability of welded pressure pipe with circumferential surface crack wascalculated by using three dimensional stochastic finite element method. This method has overcomethe shortcomings of conservative results in safety assessment with deterministic fracture mechanicsmethod. The calculation of reliability was based on three dimensional elastic-plastic stochastic finiteelement program which was developed by ourselves. The effects of variables such as fracturetoughness, bending moment and the depth of the circumferential surface crack on the structurereliability were also discussed. The calculation results indicate that the crack depth has great effect onthe reliability of the welded pipe. When the mean value of the crack depth is changed from 3mm to7mm, the failure probability of the welded pipe will change from 10-8 to 10-2. The bending momentalso has great effect on the reliability of the welded pipe. When the mean value of moment is changedfrom10000 N.m to 15000 N.m, the failure probability of the welded pipe increases dramatically forthe same circumferential crack depth. Irrespective of the changing of moment, the pipe has higherreliability if the crack depth is less than 5mm(a/t〈0.5, t is the thickness of the pipe). The method hasput forward a new way for safety assessment of welded pipe with circumferential surface crack
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 353-358 (Sept. 2007), p. 2513-2516 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The reliability of welded pressure pipe with circumferential surface crack was calculated byusing 3-D stochastic finite element method. This method has overcome the shortcomings of conservativeresults in safety assessment with deterministic fracture mechanics method. The calculation of reliabilitywas based on 3-D elastic-plastic stochastic finite element program which was developed by ourselves.The effects of variables such as bending moment, the inner pressure on the structure reliability werediscussed. The calculation results indicate that the bending moment has great effect on the reliability ofthe welded pipe, and the inner pressure has little effect on the reliability of the welded pipe if the innerpressure is less than 10MPa. If the mean value of the inner pressure changed from 0.5MPa to 30MPa, thefailure probability will changes from 10-6 to 10-2. The bending moment also has great effect on thereliability. When the mean value of moment is changed from10000 Nm to 15000 Nm, the failureprobability of the welded pipe increases dramatically for the same inner pressure. Irrespective of thechanging of moment, the pipe has higher reliability if the inner pressure is less than 6 MPa. The methodhas put forward a new way for safety assessment of welded pipe with circumferential surface crack
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 368-372 (Feb. 2008), p. 1280-1283 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Nanostructured coatings are experiencing a rapid development in recent years due to theirpotential applications in a wide variety of technological areas. In order to improve the properties ofthermal barrier coatings, nanostructured 8 wt% yttria partial stabilized zirconia coatings were depositedby air plasma spraying with reconstituted nanoparticles on titanium alloy substrates. For comparison, theconventional counterparts were also fabricated. Their microstructures were investigated by usingtransmission electron micrograph and scanning electron micrograph. Their mechanical behaviors wereevaluated via Vickers microhardness test and tensile test. The results indicate that the nanostructuredzirconia coatings with original nanostructure and columnar grains have higher microhardness and adhesivestrength than the conventional counterparts. Both the nanostructured coating and the conventionalcoating exhibit a bimodal distribution of microhardness values, which are analyzed via Weibull statistics.This phenomenon is attributed to the presence of molten and non-molten parts in the coatings
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 347 (Sept. 2007), p. 601-606 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Crack damage brings a serious threat to the safety of mechanical and civil structures, andthe problem of incipient damage identification of structures has been paying attention as a puzzle bymany researchers in recent years. To seek for an alternative solution of the problem, a method forincipient crack localization using the slope of the anti-resonance curve is proposed in this paper.The method makes use of the driving-point mechanical impedance characteristics of cracked beamsstimulated by harmonic force. To characterize the local discontinuity due to the presence of crack, asimplified rotational spring model is presented to model the crack. Subsequently, the proposedmethod is verified by a numerical example of cracked beam under simple support or cantileverboundary conditions
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 373-374 (Mar. 2008), p. 260-263 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The wear-resistance, corrosion resistance, hardness can be greatly increased by using lowtemperature QPQ complex salt-bath treatment. And it is a new strengthening method withoutdistortion in the treating process. The surface of 4Cr14Ni14W2Mo steel was treated using thismethod. The microstructure and depth of the treated surface for the steel were analyzed using SEM.The sliding wear resistance was tested on the M-2000 tester and the micro-hardness was tested using401MVA microscopy hardness tester. The corrosion resistance was tested in the 5%NaCl water byusing spraying method. The experimental results indicate that a certain depth of white layer anddiffusion layer of the steel can be obtained by using low temperature QPQ complex salt-bathtreatment. The nitriding compound layer with high hardness, superior wear resistance and stablemicrostructure, can also be obtained on the surface of the parts. The highest hardness in the surface isHV0.11012. The surface hardness is 2.8 times higher than that of inner part. The depth of white layer isfrom 10 to 12μm. The experimental results and applied results show that the low temperature QPQcomplex salt-bath treatment has many advantages, such as fast nitriding speed, uniform heating, shortprocess time, low treating temperature, small distortion, high production rate, low cost, stablenitriding quality no pollution and so on
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 353-358 (Sept. 2007), p. 54-57 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The effect of undissolved ferrite amount on impact fatigue properties and failure mechanismwere studied by using 42CrMo steel with subcritical quenching process The amount of undissolvedferrite were 0%, 10% and 15%, respectively. The experimental results show that the existence ofundissolved ferrite can not only change the microstructure, but also increase the impact fatigue life Theimpact fatigue life elongates with increasing of amounts of undissolved ferrite The grain can be fined byusing subcritical quenching process and the area of phase boundaries can also be greatly increasedbecause of undissolved spheroidal carbide. The martensite and carbide form can also be changed byusing subcritical quenching process The stress relaxation due to the moving of dislocations inside theferrite and the promotion of strength due to occurring of plastic deformation and the enwindeddislocations are main reasons of improving the impact fatigue life. The impact fatigue life elongateswith the increase of amounts of undissolved ferrite before the amount of undissolved ferrite reaches 10%.Under the experiment conditions, when the amount of undissolved ferrite is 10%, the impact fatigue lifewill be the longest
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  • 9
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Ca1-xSrxBi4Ti4O15 thin films were fabricated by sol-gel method on Pt(100)/Ti/SiO2/Sisubstrates. Influence of Sr content on the microstructure and ferroelectric properties of Ca1-xSrxBi4Ti4O15thin films were systematically studied. The results indicate that Ca0.4Sr0.6Bi4Ti4O15 thin film has betterferroelectric properties with remanent polarization (2Pr) of 29.1+C/cm2, coercive field (2Ec) of 220kV/cm. Furthermore, the film has good fatigue resistance. The better ferroelectric properties ofCa0.4Sr0.6Bi4Ti4O15 thin film originate from the relatively high concentration of a-axis oriented grains
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  • 10
    Publication Date: 2019-07-25
    Description: Implantation of the blastocyst into the uterus is the gateway for further embryonic development in mammals. Programming of blastocyst to an implantation-competent state known as blastocyst activation is the determining factor for implantation into the receptive uterus. However, it remains largely unclear how the blastocyst is globally programmed for implantation. Employing a delayed implantation mouse model, we show here that the blastocyst undergoes extensive programming essential for implantation. By analyzing the transcriptional profile of blastocysts with different implantation competency, we reveal the dynamic change in the biosynthesis, metabolism, and proliferation during blastocyst reactivation from diapause. We also demonstrate that reactivation of the X chromosome, one of the most important events during periimplantation of female embryonic development, is not completed even in blastocysts under conditions of dormancy, despite long term suspension in the uterus. Moreover, the mural trophectoderm (TE), but not the polar TE, differentiates to be more invasive through the weakened cell-cell tight junctions and extracellular matrices (ECMs). By analyzing the differentially expressed profile of secretory proteins, we further demonstrate that the blastocyst functions as a proinflammatory body to secrete proinflammatory signals, such as TNFα and S100A9, thereby triggering embryo-uterine attachment reaction during implantation. Collectively, our data systematically and comprehensively disclose the programming of blastocyst reactivation from diapause for implantation and uncover previously undefined roles of blastocyst during implantation.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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