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      20 March 2011, Volume 0 Issue 3 Previous Issue    Next Issue
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    Study on the Preparation of the Prealloyed Powder and Its Application for Diamond Tools
    XIE Zhi-gang, QIN Hai-qing, LIU Xin-yu, WANG Jin-bao, JIANG Jian-feng
    2011, 0 (3): 1-5,64.  
    Abstract ( 343 ( PDF (1347KB)( 293 Citation
    FeCoCu prealloyed powder was prepared by coprecipitation method.The effects of the concentration of solution,temperature of coprecipitation,temperature and time of thermal decomposition on the yield and the particle size of the prealloyed powder were analyzed.The results show that good FeCoCu prealloyed powder can be prepared by coprecipitation method.The yield and the particle size increase with increasing the concentration of solution and the temperature of coprecipitation,respectively.The oxygen content of powder decrease and the particle size increase with increasing the temperature of thermal decomposition.The bulk samples sintered at 850℃ have high flexural strength,hardness and density.The welding intensity of FeCoCu prealloyed powder has satisfied the En13236-2001 standard on safety.The laser welding transition layer with FeCoCu prealloyed powder has higher welding intensity,better security and reliability than that of the certain overseas company.
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    Property and Preparation of Porous NiTi Shape Memory Alloy
    MA Xu-liang, LI Li, ZHU Cheng-wu, WANG Xiang, ZHENG Yu-feng
    2011, 0 (3): 6-10,59.  
    Abstract ( 406 ( PDF (1904KB)( 302 Citation
    Porous NiTi shape memory alloy(NiTi SMA) was fabricated by powder metallurgy technology using ball milled NiTi powder as raw material and adding urea as a pore-forming agent.The effects of sintering temperature,holding time and pre-forming pressure on the microstructure and mechanical properties of the prepared porous NiTi SMA was studied.The results show that: compared with conventional sintering of mixture powder of Ni and Ti,the phase constituents of the porous NiTi alloy made by this method is more pure.And with the increasing of the sintering temperature,the pore size of porous NiTi alloy gradually increases,the pore distribution tends to be uniform,and compression strength is increased.With the extended holding time,pore size is decreased,the phenomenon of liquefaction is obvious and the strength is increased.There is an optimal value of the pre-forming pressure,and the porous NiTi alloy products can be well produced by the optimal pre-forming pressure.And the process of adding 70% pore-forming agent,pre-forming under the pressure of 150MPa,and holding at 1050℃ for 5h were ultimately determined,the porous NiTi alloy fabricated under the conditions has excellent property.
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    Research on Mechanical Stability of Austenite in TRIP Steels
    XIONG Zi-liu, CAI Qing-wu, JIANG Hai-tao, TANG Di
    2011, 0 (3): 11-15.  
    Abstract ( 341 ( PDF (1048KB)( 253 Citation
    Mechanical stability of austenite in TRIP steels was studied using techniques such as tension test,XRD,EBSD,SEM,TEM.The results showed that austenite converted fast at early tension,and slow at upper tension.With the different carbon content,the increasing rate of convention percent of austenite was different in the same tension stage.Austenite which dimension exceed 1μm and allocated on grain boundary or phase boundary almost completely transformed to martensite at early tension,while austenite which dimension less than 1μm would transform to martensite at upper tension,which could release the stress concentration on grain or phase boundary and contributed a lot to TRIP effect.Austenite which allocated in ferrite was of good mechanical stability and not liable to transform to martensite in the whole tension test,and some big dimension austenite would transform to M-A island.
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    Preparation and Visible Light Photocatalytic Activity of Nitrogen-doped Nano-TiO2 Powders
    ZHAO Hong-sheng, GUO Zi-bin, LI Zi-qiang, ZHANG Kai-hong
    2011, 0 (3): 16-19,90.  
    Abstract ( 365 ( PDF (1453KB)( 294 Citation
    N-doped nano-TiO2(anatase) powders were prepared by calcining titania gel precursor at different temperatures.The gel precursor was obtained by improved sol-gel method using tetrabutyl titanate and urea as source.The samples were characterized and analyzed by XRD,XPS and UV-Vis diffuse reflectance spectroscopy(DRS).The results show that nitrogen element is successfully introduced to titania crystal lattice,and the nitrogen content decreases with the increase in calcination temperature and time.UV-Vis diffuse reflectance spectroscopy(DRS) results indicate that all samples have a red shift,and the absorption band of the sample calcined at 400℃ for an hour shifted up to 700nm.The photodegradation of methylene blue shows that N-doped nano-TiO2 powders have high visible-light photocatalytic properties.
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    Experiments Research on Warm Bending of the AZ31 Magnesium Alloy Profiles
    LIU Jin-song, WANG Qi, XIAO Han, ZHANG Shi-hong
    2011, 0 (3): 20-23.  
    Abstract ( 314 ( PDF (924KB)( 335 Citation
    By using the self-made bending tools,the bending forming experiments of AZ31 magnesium alloy profiles were accomplished,and the effects of the temperature and bending angle on the bending ability were researched.The results indicate that the bending parts of AZ31 magnesium alloy profile can be produced by using warm bending process;the thickness of external rib of the profiles is decreased after bending,the thickness of the remaining rib is increased;on the condition of the same bending angle and the same preheating temperature of the die,the springback angle of AZ31 magnesium alloy profiles is decreased with the increasing of the blank temperature.With the influenced of temperature increasing,the fracture mode of AZ31 magnesium alloy profiles has transferred from the ductile-brittle fracture mode to ductile fracture mode in trend.
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    Synthesis and Properties of Novel Red-emitting Phosphor Li2SrSiO4:Eu3+ for White LED
    ZHAI Yong-qing, WANG Xin, FENG Shi-hua, LIU Yi-lan, YOU Zhi-jiang
    2011, 0 (3): 24-27.  
    Abstract ( 247 ( PDF (1096KB)( 614 Citation
    A novel red-emitting phosphor Li2SrSiO4:Eu3+ was synthesized by gel-combustion method,using the metal nitrates as raw materials,and tetraethoxysilane as silica source.The formation process,structure and luminescence properties of as-synthesized Li2SrSiO4:Eu3+ were investigated by FI-IR,XRD and fluorescence spectrophotometer respectively.The results show that the goal product Li2SrSiO4:Eu3+ can be obtained after the precursor obtained from the combustion of dry gel was calcined at 700℃ for 3h.The as-synthesized sample has hexagonal crystal structure and P3121 space group,and unit cell parameter is a=0.5012nm,c=1.2360nm.The excitation spectrum shows a broad band,and the strongest excitation peak is at 396 nm.The strongest emission peak is at 618 nm,which is ascribed to 5D07F2 characteristic transition of Eu3+.When the mole fraction x of doped Eu3+ is in the range of 0.04-0.24,the luminescence intensity of the sample increases gradually with the the increase of Eu3+ concentration.It is interesting that no concentration quenching occurs.The synthesized phosphor can absorb near-UV light around 396nm effectively,so it is a suitable red-emitting phosphor for white light-emitting diodes excited by 350-410nm InGaN chip.
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    Preparation and Characterization of Carbon-encapsulated Copper-water Nanofluid by Chemical Treatment Method
    PANG Jin-shan, ZHANG Hai-yan, WU Qi-guang, LIN Jin, XU Zhuo-wen, TU Wen-ying
    2011, 0 (3): 28-31,35.  
    Abstract ( 314 ( PDF (1144KB)( 219 Citation
    Carbon-encapsulated copper nanoparticles were synthesized by carbon arc discharge technology,carbon-encapsulated copper-water nanofluid was prepared by two different method,chemical treatment with H2O2 and adding SDBS dispersant respectively.The effect of dispersion method on thermal transport of nanofluid was studied.The test indicated that the nanofluid prepared by chemical treatment to carbon-encapsulated copper nano-particle had higher thermal conductivity than that prepared by adding SDBS dispersant.There was a 60% enhancement in thermal conductivity with 2.0%(mass fraction) carbon-encapsulated copper loading using chemical treatment preparation method.
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    Effect of Annealing on the Microstructure and Hardness of V-5Cr-5Ti Alloy
    HUANG Shu-ke, ZHOU Dan-chen, LI Chang-an, LI Jing-min, LIU Bao
    2011, 0 (3): 32-35.  
    Abstract ( 318 ( PDF (888KB)( 180 Citation
    The variations of hardness and microstructure with annealing temperature of V-5Cr-5Ti alloy,and the effect of minor impurity elements were studied.The annealing was done in vacuum heat treatment furnace.The tensile deform and hardness were tested using universal material testing machine and Vickers hardness tester.The phase structure was identified using X-ray diffraction(XRD).The microstructure was observed using scanning electronic microscope(SEM) and optical microscope(OM).The results indicated that the hardness of deformed V-5Cr-5Ti alloy is improved obviously.The hardness decreases with annealing temperature increasing from 700℃ to 1000℃,and reach minimum value at 900℃ and 1000℃.After oil-quenching at 1100℃,the hardness is not descending but to higher value,and the microstructure is non-homogeneous where some grains grow up abnormally.
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    Tempering Microstructure and Mechanical Properties of Low Carbon Bainitic Steel Directly Quenched
    WANG Li-jun, WU Hui-bin, YU Wei, CAI Qing-wu
    2011, 0 (3): 36-39,44.  
    Abstract ( 305 ( PDF (1333KB)( 371 Citation
    Effects of different tempering temperature on the microstructure and mechanical properties of the directly-quenched steel were investigated by SEM,TEM and other experimental methods.The results indicate that the tested steel obtain the best comprehensive mechanical properties with tensile strength of 805MPa,yield strength of 719MPa,elongation of 25.8% and impact energy of 106J at-20℃.The recovery of lath bainite become even more clear with increasing tempering temperature.The small-angle grain boundaries in lath bainite gradually disappear through motion,merging and reorganization of dislocation,which cause lath wider.It was found that bainite lath boundaries blurred,the dislocation network located in bainite and the precipitation of(Nb,Ti)(C,N) composite phase with the average size of 10-20nm after tempering at 620℃.Mechanical properties with tempering temperature show non-monotonic nature,which is ascribed to the comprehensive mechanism including the recovery softening process of dislocation substructure,and the strengthening mechanism due to the dissolution of carbon and precipitation of the second phase in bainite during tempering.
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    Effect of Ag on the Properties of Heavily Deformation Processed Cu-14Fe In situ Composites
    ZHOU Hai-tao, WEN Sheng-fa, LIU Ke-ming, LIU Zhi-Chao, ZHAO Zhong-kai, LI Qing-bo
    2011, 0 (3): 40-44.  
    Abstract ( 325 ( PDF (1252KB)( 244 Citation
    The Cu-14Fe alloy and Cu-14Fe-0.1Ag alloy were prepared by using melting.Then the two alloys were treated by solution-cold drawing and isochronal aging for 1 hour,the deformation ratio was 4,5,6,7 and 8,respectively.The effects of solution mode and deformation ratio on mechanical and electrical properties of the alloys were studied,the microstructure of the alloy was also studied by metallograph and SEM.The results indicated that the conductivity and strength of the alloy could be obtained higher value by the addition of element of Ag.Meanwhile it can be obtained combination of proper value of strength and conductivity by appropriate isochronal aging treatment.
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    Photo Degradation Behavior of Media Density Polythene Under Xisha(Paracel) Islands Environment
    LU Lin, SHI Yu-ye, GAO Jin, LI Xiao-gang
    2011, 0 (3): 45-49,54.  
    Abstract ( 326 ( PDF (1323KB)( 366 Citation
    The exposure test of media density polythene(MDPE) was carried out for different time periods up to one year in Xisha(Paracel) Islands.The changes of appearance,morphology,mechanical properties and chemical structures were monitored by spectrophotometer,glossmeter,microscope,computer-controlled tensile testing,hardness measurements and Fourier Transform Infrared(FTIR) spectroscopy.The results showed that during the aging period,the color abbreviation and hardness increased,while the gloss,the retention of tensile strength and that of elongation at break decreased.The aging evaluation parameter Z was postulated,which can present the common of those tested properties well,which showed a stepwise increasing tendency of aging rate with the extending of exposure time.
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    Microstructure and Property of Laser Cladding Fe-Ti-V-Cr-C Alloy Coatings
    WANG Xiao-rong, WANG Xin-hong, DU Bao-shuai, WANG Cheng-wei
    2011, 0 (3): 50-54.  
    Abstract ( 523 ( PDF (1146KB)( 253 Citation
    Fe-Ti-V-Cr-C hardfacing coatings were produced by laser cladding,the influence of ferrochromium on the microstructure and property of the coatings was investigated by optical microscope(OM),X-ray diffraction(XRD),scanning electron microscope(SEM),micro-hardness tester and wear tester.The results show that the stable carbide hard phases are generated through in-situ reaction between ferrotitanium,ferrovanadium,ferrochromium and graphite.The multiple TiC-VC presented graininess or efflorescent and intermittent Cr7C3 emerged reticulation evenly disperse in the coating,which largely increase the micro-hardness and wear resistance of the coating.The micro-hardness of the coatings increases with increasing ferrochromium content.The coating,which contented 12%(mass fraction) ferrochromium,holds compact microstructure and excellent wear resistance.Under the same condition,its mass loss is only one seventh of that of the substrate.However,when the ferrochromium content is beyond 15%,coarse Ledeburite which may cause crack and failure of coating is found.
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    Effects of C Current on Microstructures and Properties of Magnetron Sputtered Cr/C and Cr/C/N Composite Coatings
    JIA Gui-xi, LI Yan, LI Hong-tao, JIANG Bai-ling
    2011, 0 (3): 55-59.  
    Abstract ( 364 ( PDF (1522KB)( 216 Citation
    Using magnetron sputtering technique,Cr/C and Cr/C/N composite coatings were prepared on the substrate of 45# steel by adjusting C target current process parameters.Coating microstructures were characterized by energy dispersive spectroscopy(EDS),X-ray diffraction(XRD) and scanning electron microscopy(SEM).The mechanical properties were tested by the HX-1000 type microvickers hardness tester,the ball-disc friction and wear tester and the optical microscopy(OM).The results showed that,with the C current increased,Cr/C and Cr/C/N coatings microstructures became more uniform and dense,hardness increased,toughness strengthened,and wear resistance markedly improved.The coating of C current 1.2A has excellent friction and wear properties.The comprehensively mechanical performance of Cr/C/N coating is better than that of Cr/C coating.
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    Stress Corrosion Cracking Model Based on Experiment and Gray Theory for High Strength Aluminum Alloy
    LIU Jian-hua, HAO Xue-long, LI Song-mei, YU Mei
    2011, 0 (3): 60-64.  
    Abstract ( 383 ( PDF (811KB)( 257 Citation
    The making precrack in 3.5% NaC1 solution was used for testing the variation of the stress corrosion crack length with time for 2124 high strength aluminum alloy.The variation law of the crack growth rate with the time and the threshold stress intensity for stress corrosion cracking were obtained.The fractograph was also analyzed.According to the fundamental rules of crack propagation,the grey prediction model GM(1,1) was used for predicting the stress corrosion crack length based on the values experimentally measured,and the predicted results were examined.The results showed that the crack growth rate reduced with the increasing of the corrosion time,and intergranular fracture could be observed.The crack resumed growth was driven by the corrosion production accumulation.It is also shown that the stress corrosion crack length prediction model GM(1,1) realized by the MATLAB program can produce values closely approximating the measured ones,and the errors were relatively small,which indicated the practical valuation of the model.Using the model,the test time can be reduced,that is to say,the model has provided a scientific evidence for evaluating the material stress corrosion cracking sensitivity rapidly and scientifically.
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    Preparation and Photoluminescent Properties of Al Doped and Al-N Codoped ZnO Nanorods
    LIU Bao, WU You-shi, ZHANG Chang-qiao
    2011, 0 (3): 65-69.  
    Abstract ( 340 ( PDF (1281KB)( 270 Citation
    Al doped ZnO(AZO) nanorods were firstly synthesized by hydrothermal method,and then Al-N co-doped ZnO(ANZO) nanorods were prepared by annealing the AZO nanorods at 550℃ in ammonia atmosphere.The samples were characterized using X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),energy dispersive X-ray spectroscopy(EDS) and photoluminescence(PL).The results show that the as-prepared AZO and ANZO nanorods are all hexagonal wurtzite structure,the diameter of the ZnO nanorod can be reduced by doping Al;Al and N elements have been effectively doped into ZnO nanorods through this preparation technique,and the content of N element increases with the increase of Al doping concentration.Room-temperature photoluminescence(PL) measurements show that the obtained both AZO and ANZO nanorods have a strong UV emission peak at 390nm and a weak blue emission peak at 468nm.Compared with the PL spectrum of the AZO nanorods,the green emission peak at 555nm of the ANZO nanorods is almost disappear.These results indicate that Al doped and Al-N co-doped ZnO nanorods possess potential application for the development of one-dimensional nanoscale optoelectronic devices.
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    Effects of Sm on Microstructure Refinement of Mg-10Y Alloy
    ZHANG Qing, LI Quan-an, JING Xiao-tian, ZHANG Xing-yuan
    2011, 0 (3): 70-72,77.  
    Abstract ( 326 ( PDF (814KB)( 204 Citation
    Refinement of Mg24Y5 phase is a key for the further increase of mechanical properties of Mg-10Y alloy.The refinement effects of rare earth element Sm on Mg24Y5 phase and base microstructure were investigated.The results show that Sm addition improves the morphology of Mg24Y5 phase and promotes the formation of fine and dispersed Mg24Y5 particles.Meanwhile,Sm addition further refines the microstructure of base alloy by the effect of solid solution.The improvement of microstructure leads to the increase of mechanical properties at elevated temperature.
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    Hot Tensile Deformation Behavior of ZA73 Magnesium Alloy
    ZHANG Jing, LIAO Qian, DOU Yu-chen, HE Qu-bo, LUO Xiao-dong
    2011, 0 (3): 73-77.  
    Abstract ( 301 ( PDF (1744KB)( 302 Citation
    The hot tensile deformation behavior of ZA73 magnesium alloy were investigated in the temperature range of 150-300℃ and strain rates of 0.001s-1 and 0.1s-1,respectively,by thermo-mechanical simulation.The hot-forming processing parameters were then determined,combined with microstructural observation and real extrusion experiment.The results showed that the deformation temperature and strain rate are the key factors influencing the flow stress and plasticity.The flow stress decreases with the increase of temperature and the decrease of strain rate.At lower strain rate,the plasticity becomes worse when the deformation temperature is higher than 200℃.Comparatively,at higher strain rate,the plasticity improves with the temperature raising except at 250℃.Moreover,when deformed in the temperature range of 200-250℃,net-worked dendritic microstructural feature disappears,instead,the second phases disperse in the matrix in the form of particles of smaller size.The microstructure goes coarse when deformed at 300℃ under lower strain rate.It is concluded that the increase of the amount of small particles and the coarsening of microstructure lead to the deterioration of hot plasticity.Higher strain rate and temperature is considered to favour hot deformation.Bars were extruded at 350℃ under higher strain rate of about 0.1s-1.The tensile ultimate strength of the as-extruded bar reaches 355MPa,in the mean time maintaining a high elongation of 19%.In addition to,the grain size was refined to 3-6μm.
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    Study on Short-term Corrosion Behavior of X80 Pipeline Steel in Huo'erguosi Soil with Saturated Water
    XU Cong-min
    2011, 0 (3): 78-81,86.  
    Abstract ( 323 ( PDF (477KB)( 167 Citation
    The short-term corrosion behavior of X80 pipeline steel was investigated in Huo'erguosi soil with saturated water using electrochemical measurement,scanning electron microscopy(SEM) and energy dispersive spectrum(EDS) analysis.The results showed that the corrosion rate of X80 steel presented the variational trend of rapid increase→sharp decrease→slow increase with the increase of corrosion time,and corrosion tendency increases,this is induced by change of corrosion morphology from uniform corrosion to localized corrosion.The corrosion product is basically iron oxides and iron sulfides.The corrosion resistance and corrosion morphology of X80 steel samples is dependent on the integrality and compactness of corrosion product films.
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    Alloying Effect on Microstructure and Mechanical Properties of Directionally Solidified Ti-Al-Nb Alloy
    DUAN Qiu-qi, LUAN Qing-dong, LIU Jing, WANG Xiao-guang, PENG Liang-ming
    2011, 0 (3): 82-86.  
    Abstract ( 367 ( PDF (2298KB)( 153 Citation
    Cr-and Mo-doped high-Nb containing Ti-Al alloys were fabricated using directional solidification process.Their microstructures and mechanical properties were examined.Results showed that both the two alloys displayed basket-weave type microstructures.The laths in Ti-16Al-12Nb-3Cr-1Mo tended to be inclined with a smaller angle to the withdrawal direction than Ti-16Al-12Nb alloy although the limited thermal gradient and comparatively high withdrawal velocity were employed.Remarkable enhancement in strength and ductility was achieved at room temperature and 650℃.
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    The Preparation and the Properties of Hydroxyl Silsesquioxane/Epoxy Resin Composites
    ZHANG Wan-li, SONG Jiang-xuan, CHEN Guang-xin, LI Qi-fang
    2011, 0 (3): 87-90.  
    Abstract ( 349 ( PDF (719KB)( 285 Citation
    Cyclohexyl silsesquioxane was synthesized by the hydrolytic condensation of cyclohexyl trichlorosi1ane in acetonitrile,and characterized by FT-IR and 29Si-NMR.The hydroxyl silsesquioxane was prepared by adding NMe4OH to the solution of cyclohexyl silsesquioxane in THF by controlling the suitable reaction condition,such as reaction time and the temperature.Epoxy resin was modified with hydroxyl silsesquioxane,and the thermal properties,dielectric properties and the hydrophobicity of the composites with different content of hydroxyl silsesquioxane were investigated with thermogravimetric analysis(TGA),dielectric constant and contact angle analysis.It was experimentally shown that the thermal stability,the dielectric properties and the the hydrophobicity of the composites were improved with the increase of the content of hydroxyl silsesquioxane.
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    Research Progress of Al2O3 Ceramic Composites
    CHEN Wei-ping, HAN Meng-yan, YANG Shao-feng
    2011, 0 (3): 91-96.  
    Abstract ( 345 ( PDF (1340KB)( 352 Citation
    The toughening technology of Al2O3 ceramic and strengthening of metal matrix composites with Al2O3 ceramic are described.It is pointed out that compound toughening will be the better choice for the toughening technology of Al2O3 ceramic in the future;Al2O3 ceramic/metal composites with network structure have better mechanical properties;self-forming Al2O3 protective layer on the surface of metal is an effective method for improving resisting corrosion and reducing costs;bionic design and computer simulating are very useful for developing new network Al2O3 ceramic skeleton.
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