The effects of heat treatment on the dynamic compressive properties and energy absorption characteristics of open cell aluminum alloy foams (Al-Mg-Si alloy foam and Al-Cu-Mg alloy foam) produced by infiltrating proces...The effects of heat treatment on the dynamic compressive properties and energy absorption characteristics of open cell aluminum alloy foams (Al-Mg-Si alloy foam and Al-Cu-Mg alloy foam) produced by infiltrating process were studied. Two kinds of heat treatment were exploited: age-hardening and solution heat treating plus age-hardening (T6). The split Hopkinson pressure bar (SHPB) was used for high strain rate compression test. The results show that both age-hardened and T6-strengthened foams exhibit improved compression strength and shortened plateau region compared with that of foams in as-fabricated state under high strain rate compression, and the energy absorption capacity is also influenced significantly by heat treatment. It is worthy to note that omitting the solution treating can also improve the strength and energy absorbed much.展开更多
The nearly equiaxed grains of Mg9AlZnY alloy were obtained by vibrating solidification in lost foam casting(LFC) and the microstructure of Mg9AlZnY alloy was analyzed.On this basis,the morphology and size of α-Mg gra...The nearly equiaxed grains of Mg9AlZnY alloy were obtained by vibrating solidification in lost foam casting(LFC) and the microstructure of Mg9AlZnY alloy was analyzed.On this basis,the morphology and size of α-Mg grains fabricated by semi-solid isothermal heat treatment(SSIT) at 530 ℃ and 570 ℃ holding different time were studied.The results show that the main constituent phases of Mg9AlZnY alloy are α-Mg,β-Mg17Al12 and Al2Y,and the Y can greatly refine α-Mg grains.The distribution of α-Mg grains equivalent diameters between 20 and 100 μm is up to 87%,and the average roundness of α-Mg grains reaches 1.37 in the specimen obtained at 570 ℃ and holding time 60 min.According to the analysis of solidification kinetics and thermodynamic,binary eutectic with low melting point melts firstly on SSIT process.As the liquid fraction increases with the solute diffusibility,both of the shape and size of α-Mg grains change ceaselessly.When the liquid fraction reaches equilibrium,the α-Mg grains are gradually spheroidized under the interfacial tension,and then the α-Mg grains begin to combine and grow.Evolution of α-Mg dendritic grains on SSIT process is obviously different from that of equiaxed grains.展开更多
Porosity is a main defect in aluminum alloy castings, which is also thought to be severe in aluminum alloy castings produced by lost foam process due to the pyrolysis of the polystyrene foam pattern during pouring. Fu...Porosity is a main defect in aluminum alloy castings, which is also thought to be severe in aluminum alloy castings produced by lost foam process due to the pyrolysis of the polystyrene foam pattern during pouring. Fundamental experiments were carried out to evaluate the effect of process parameters such as the melt treatment, the cooling rate and the density of expanded polystyrene （EPS） foam on porosity in A356.2 bar casting. The effect of melt treatment including degassing and refining was investigated. The effect of cooling rate was also evaluated by changing the mold packing material such as the silica sand, the zircon sand and the steel shots. Gas entrapment due to the turbulent metal flow during mold filling in conventional molding process results in porosity. Mold filling sequence in lost foam process is different from that in conventional molding process. The effect of molten metal flow was estimated by comparing the density of the casting by conventional sodium silicate molding with that by lost foam process. Density measurement was conducted to analyze the extent of porosity in the casting. Source of the porosity in lost foam process can be divided into two factors, i.e. turbulence in molten metal flow and entraining residue or gas from the pattern during pouring.展开更多
The electrochemical method was used to remove nickel ion from spent electroless nickel plating bath (pH=5 3). An electrolytic cell was composed of a porous nickel foam cathode and an inert RuO 2/Ti anode. Nickel ions ...The electrochemical method was used to remove nickel ion from spent electroless nickel plating bath (pH=5 3). An electrolytic cell was composed of a porous nickel foam cathode and an inert RuO 2/Ti anode. Nickel ions were reduced and deposited on the surface of the nickel foam cathode. The effect of current density (i), linear velocity of wastewater(v), gap between cathode and anode(d C/A) and reaction time(t) on nickel removal rate and current efficiency were studied. As reaction time prolonged, nickel removal rate increased while current efficiency decreased. And larger v and smaller d C/A can enhance nickel removal rate and increase current efficiency by promoting mass transfer and dropping concentration polarization. The effect of current density on nickel removal by electrochemistry was related to other parameters. After three hours’ electrolysis with i=1 0 A/dm2, v=18 5 cm/min and d C/A=0 5 cm, nickel removal rate and current efficiency reached 85 6% and 29 1%, respectively.展开更多
目的探讨原发性大隐静脉曲张传统开放性手术与激光治疗联合泡沫硬化术对机体免疫系统的影响。方法按照手术方式将104例择期行大隐静脉曲张手术的患者分为激光治疗联合泡沫硬术组(MIS组,53例)和传统开放性手术组(OS组,51例)。分别于术前...目的探讨原发性大隐静脉曲张传统开放性手术与激光治疗联合泡沫硬化术对机体免疫系统的影响。方法按照手术方式将104例择期行大隐静脉曲张手术的患者分为激光治疗联合泡沫硬术组(MIS组,53例)和传统开放性手术组(OS组,51例)。分别于术前和术后24 h采集2组静脉血测定超氧化物岐化酶(SOD)、IL-1β、IL-6、IL-8、IL-10、TNF-α、干扰素-γ(IFN-γ)水平。采用流式细胞术检测T淋巴细胞亚群及自然杀伤细胞(NK)的比例变化。采用单细胞测序(scRNA-seq)技术检测外周血免疫细胞差异基因表达。结果MIS组术后IL-1β、IL-8水平较术前高(P均<0.05),术前与术后的SOD、IL-6、IL-10、TNF-α、IFN-γ水平比较差异无统计学意义(P均>0.05);OS组上述指标术前与术后比较差异均有统计学意义(P均<0.05)。MIS组术前与术后T淋巴细胞亚群及NK比例比较差异均无统计学意义(P均>0.05);OS组术后24 h CD8^(+)T细胞比例升高,NK比例降低(P均<0.05)。术后24 h外周血免疫细胞表达差异基因功能富集分析提示OS组术后缺氧应答、IFN应答及NF-κB等炎症通路较MIS组上调。结论大隐静脉曲张激光治疗联合泡沫硬化术对机体系统免疫炎症及缺氧反应影响较小,能够更好地维持机体的免疫平衡,较大程度保留机体原有免疫系统抵御微生物入侵的能力。展开更多
乳清蛋白作为主要蛋白成分,与婴儿配方奶粉的起泡特性息息相关。脱盐乳清粉D70、D90和浓缩乳清蛋白(whey protein concentrate,WPC)是婴儿配方奶粉的3种主要乳清蛋白原料。该研究表征并比较了热处理工艺下3种乳清蛋白原料起泡特性、理...乳清蛋白作为主要蛋白成分,与婴儿配方奶粉的起泡特性息息相关。脱盐乳清粉D70、D90和浓缩乳清蛋白(whey protein concentrate,WPC)是婴儿配方奶粉的3种主要乳清蛋白原料。该研究表征并比较了热处理工艺下3种乳清蛋白原料起泡特性、理化与结构特性变化,探究起泡性与理化及结构变化影响规律。结果表明,D70的起泡能力(95.62%)和泡沫稳定性(65.02%)最高,其次为D90(73.97%/24.47%),最小是WPC(60.39%/13.91%)。不同加热处理均提高了乳清蛋白的起泡能力,而其中以80℃,20 s影响最大。通过粒径、电位、溶解度表征蛋白的理化特性,借助光谱技术测定蛋白的结构特性。皮尔逊相关性分析表明,起泡能力及泡沫稳定性与Zeta电位(0.78/0.69)、β-转角含量(0.82/0.67)、无规则卷曲含量(0.74/0.60)、表面疏水性(0.67/0.46)呈正相关,与α-螺旋呈负相关(-0.81/-0.84)。研究结果对于改善婴儿配方奶粉冲调起泡性具有指导意义。展开更多
基金Project(90205018) supported by the National Natural Science Foundation of China
文摘The effects of heat treatment on the dynamic compressive properties and energy absorption characteristics of open cell aluminum alloy foams (Al-Mg-Si alloy foam and Al-Cu-Mg alloy foam) produced by infiltrating process were studied. Two kinds of heat treatment were exploited: age-hardening and solution heat treating plus age-hardening (T6). The split Hopkinson pressure bar (SHPB) was used for high strain rate compression test. The results show that both age-hardened and T6-strengthened foams exhibit improved compression strength and shortened plateau region compared with that of foams in as-fabricated state under high strain rate compression, and the energy absorption capacity is also influenced significantly by heat treatment. It is worthy to note that omitting the solution treating can also improve the strength and energy absorbed much.
基金Project(2007AA03Z113) supported by the National High-Tech Research and Development Program of ChinaProject (50775085) supported by the National Natural Science Foundation of China
文摘The nearly equiaxed grains of Mg9AlZnY alloy were obtained by vibrating solidification in lost foam casting(LFC) and the microstructure of Mg9AlZnY alloy was analyzed.On this basis,the morphology and size of α-Mg grains fabricated by semi-solid isothermal heat treatment(SSIT) at 530 ℃ and 570 ℃ holding different time were studied.The results show that the main constituent phases of Mg9AlZnY alloy are α-Mg,β-Mg17Al12 and Al2Y,and the Y can greatly refine α-Mg grains.The distribution of α-Mg grains equivalent diameters between 20 and 100 μm is up to 87%,and the average roundness of α-Mg grains reaches 1.37 in the specimen obtained at 570 ℃ and holding time 60 min.According to the analysis of solidification kinetics and thermodynamic,binary eutectic with low melting point melts firstly on SSIT process.As the liquid fraction increases with the solute diffusibility,both of the shape and size of α-Mg grains change ceaselessly.When the liquid fraction reaches equilibrium,the α-Mg grains are gradually spheroidized under the interfacial tension,and then the α-Mg grains begin to combine and grow.Evolution of α-Mg dendritic grains on SSIT process is obviously different from that of equiaxed grains.
基金supported by the National Natural Science Foundation of China(Nos.52071069,U1332110)the Liaoning Revitalization Talents Program,China(No.XLYC1902097)。
文摘Porosity is a main defect in aluminum alloy castings, which is also thought to be severe in aluminum alloy castings produced by lost foam process due to the pyrolysis of the polystyrene foam pattern during pouring. Fundamental experiments were carried out to evaluate the effect of process parameters such as the melt treatment, the cooling rate and the density of expanded polystyrene （EPS） foam on porosity in A356.2 bar casting. The effect of melt treatment including degassing and refining was investigated. The effect of cooling rate was also evaluated by changing the mold packing material such as the silica sand, the zircon sand and the steel shots. Gas entrapment due to the turbulent metal flow during mold filling in conventional molding process results in porosity. Mold filling sequence in lost foam process is different from that in conventional molding process. The effect of molten metal flow was estimated by comparing the density of the casting by conventional sodium silicate molding with that by lost foam process. Density measurement was conducted to analyze the extent of porosity in the casting. Source of the porosity in lost foam process can be divided into two factors, i.e. turbulence in molten metal flow and entraining residue or gas from the pattern during pouring.
文摘The electrochemical method was used to remove nickel ion from spent electroless nickel plating bath (pH=5 3). An electrolytic cell was composed of a porous nickel foam cathode and an inert RuO 2/Ti anode. Nickel ions were reduced and deposited on the surface of the nickel foam cathode. The effect of current density (i), linear velocity of wastewater(v), gap between cathode and anode(d C/A) and reaction time(t) on nickel removal rate and current efficiency were studied. As reaction time prolonged, nickel removal rate increased while current efficiency decreased. And larger v and smaller d C/A can enhance nickel removal rate and increase current efficiency by promoting mass transfer and dropping concentration polarization. The effect of current density on nickel removal by electrochemistry was related to other parameters. After three hours’ electrolysis with i=1 0 A/dm2, v=18 5 cm/min and d C/A=0 5 cm, nickel removal rate and current efficiency reached 85 6% and 29 1%, respectively.
文摘目的探讨原发性大隐静脉曲张传统开放性手术与激光治疗联合泡沫硬化术对机体免疫系统的影响。方法按照手术方式将104例择期行大隐静脉曲张手术的患者分为激光治疗联合泡沫硬术组(MIS组,53例)和传统开放性手术组(OS组,51例)。分别于术前和术后24 h采集2组静脉血测定超氧化物岐化酶(SOD)、IL-1β、IL-6、IL-8、IL-10、TNF-α、干扰素-γ(IFN-γ)水平。采用流式细胞术检测T淋巴细胞亚群及自然杀伤细胞(NK)的比例变化。采用单细胞测序(scRNA-seq)技术检测外周血免疫细胞差异基因表达。结果MIS组术后IL-1β、IL-8水平较术前高(P均<0.05),术前与术后的SOD、IL-6、IL-10、TNF-α、IFN-γ水平比较差异无统计学意义(P均>0.05);OS组上述指标术前与术后比较差异均有统计学意义(P均<0.05)。MIS组术前与术后T淋巴细胞亚群及NK比例比较差异均无统计学意义(P均>0.05);OS组术后24 h CD8^(+)T细胞比例升高,NK比例降低(P均<0.05)。术后24 h外周血免疫细胞表达差异基因功能富集分析提示OS组术后缺氧应答、IFN应答及NF-κB等炎症通路较MIS组上调。结论大隐静脉曲张激光治疗联合泡沫硬化术对机体系统免疫炎症及缺氧反应影响较小,能够更好地维持机体的免疫平衡,较大程度保留机体原有免疫系统抵御微生物入侵的能力。
文摘乳清蛋白作为主要蛋白成分,与婴儿配方奶粉的起泡特性息息相关。脱盐乳清粉D70、D90和浓缩乳清蛋白(whey protein concentrate,WPC)是婴儿配方奶粉的3种主要乳清蛋白原料。该研究表征并比较了热处理工艺下3种乳清蛋白原料起泡特性、理化与结构特性变化,探究起泡性与理化及结构变化影响规律。结果表明,D70的起泡能力(95.62%)和泡沫稳定性(65.02%)最高,其次为D90(73.97%/24.47%),最小是WPC(60.39%/13.91%)。不同加热处理均提高了乳清蛋白的起泡能力,而其中以80℃,20 s影响最大。通过粒径、电位、溶解度表征蛋白的理化特性,借助光谱技术测定蛋白的结构特性。皮尔逊相关性分析表明,起泡能力及泡沫稳定性与Zeta电位(0.78/0.69)、β-转角含量(0.82/0.67)、无规则卷曲含量(0.74/0.60)、表面疏水性(0.67/0.46)呈正相关,与α-螺旋呈负相关(-0.81/-0.84)。研究结果对于改善婴儿配方奶粉冲调起泡性具有指导意义。
