The effects of heat stress (HS) and ultra low oxygen (ULO) in controlled (CA) or modified (MA) atmosphere on chestnut (Castanea sativa L. cv. Rodiana) fruit quality and storability were investigated. Chestnuts exposed...The effects of heat stress (HS) and ultra low oxygen (ULO) in controlled (CA) or modified (MA) atmosphere on chestnut (Castanea sativa L. cv. Rodiana) fruit quality and storability were investigated. Chestnuts exposed to ULO (1% O2 for 1 h) or dipped in water bath (at 55?C for 15 min) and then stored to CA or MA conditions at 6?C for up to 90 days. The HS dipping and storage in CA or MA increased sprouting (up to 60%) as well as mould severe on chestnuts com-paring with the control. In MA conditions, HS and ULO increased respiration rate. Total starch content increased (up to 30%) in MA-HS and MA-ULO treatments comparing with the control the first 60 days of storage. The first 30 days of CA and MA storage, chestnut moisture content decreased. No major differences observed in total sugar, total fat and total phenolic content as well as in the incidence of hole with or without worm in chestnut fruit. Following sensory evaluation, 57% of panelist marked differences among treatments, while the greater preference (67%) observed in chestnut treated with HS and stored in MA. Additionally, MA-HS enhanced (up to 30%) the chestnut appearance while no difference observed in aroma, sweetness and texture among treatments and storage conditions. Thus, the impacts of HS on chestnuts maintain fruit quality, with benefits in CA storage, as increased panelists’ preference.展开更多
A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-l...A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-low oxygen sensor. Especially, it is very sensitive to measure ultra-low oxygen in molten metal. For estimating the accuracy of La beta -Al2O3 oxygen sensor, two series of oxygen activities in molten iron at different oxygen contents and different temperature were measured by both La beta -Al2O3 oxygen sensor and ZrO2 oxygen sensor. The theoretical values of oxygen activities in molten iron (3.30%C, in mass fraction) at 1723K and 1745K were also evaluated for comparing the measuring results of two sensors. At last, the error of measurement for La beta -Al2O3 oxygen sensor was discussed too.展开更多
为提高超低碳IF钢连铸可浇性和洁净度,开展了转炉底吹工艺优化、终点碳氧含量控制、顶渣改质、真空高效深脱碳技术和连铸保护浇铸工艺试验研究。结果表明:采用环缝式风口替代原有毛细管式透气砖底吹,转炉后期单管底吹强度0.086 m 3/(t&#...为提高超低碳IF钢连铸可浇性和洁净度,开展了转炉底吹工艺优化、终点碳氧含量控制、顶渣改质、真空高效深脱碳技术和连铸保护浇铸工艺试验研究。结果表明:采用环缝式风口替代原有毛细管式透气砖底吹,转炉后期单管底吹强度0.086 m 3/(t·min),搅拌能0.40 W/t,能显著提高吹炼后期搅拌能力,转炉终点钢水平均碳氧积达0.00209。通过RH快速抽真空至极限真空度,3~5 min强制吹氧和8~12 min极限真空度下脱碳效率最高。降低真空脱碳后钢水残余氧含量、优化钢包顶渣成分,可显著减少Al 2 O 3夹杂物的产生,促进顶渣对夹杂物的吸附和溶解,配合连铸保护浇铸,钢水可浇性和氧化物夹杂控制水平明显提升。展开更多
The influence of calcium treatment on non-metallic inclusions had been studied when control technology of refining top slag in ladle furnace was used in ultra-low oxygen steelmaking. A sufficient amount aluminium was ...The influence of calcium treatment on non-metallic inclusions had been studied when control technology of refining top slag in ladle furnace was used in ultra-low oxygen steelmaking. A sufficient amount aluminium was added to experimental heats for final deoxidizing during BOF tapping, and the refining top slag with strong reducibility, high basicity and high Al2O3 in ladle furnace was used to produce ultra-low oxygen steel and the transformation of nonmetallic inclusions in molten steel was compared by calcium treatment and no calcium treatment. The results show that the transformation of Al2O3--MgO - Al2O3 spinel-CaO-MgO-Al2O3 complex inclusions has been completed for aluminum deoxidation products and calcium treatment to molten steel is unnecessary when using the control technology of ladle furnace refining top slag to produce ultra-low oxygen steel, and the complex inclusions are liquid at the temperature of steelmaking and easily removable to obtain very high cleanliness steel by flotation. Further- more, the problems of nozzle clogging in casting operations do not happen and the remaining oxide inclusions in steel are the relatively lower melting point complex inclusions.展开更多
文摘The effects of heat stress (HS) and ultra low oxygen (ULO) in controlled (CA) or modified (MA) atmosphere on chestnut (Castanea sativa L. cv. Rodiana) fruit quality and storability were investigated. Chestnuts exposed to ULO (1% O2 for 1 h) or dipped in water bath (at 55?C for 15 min) and then stored to CA or MA conditions at 6?C for up to 90 days. The HS dipping and storage in CA or MA increased sprouting (up to 60%) as well as mould severe on chestnuts com-paring with the control. In MA conditions, HS and ULO increased respiration rate. Total starch content increased (up to 30%) in MA-HS and MA-ULO treatments comparing with the control the first 60 days of storage. The first 30 days of CA and MA storage, chestnut moisture content decreased. No major differences observed in total sugar, total fat and total phenolic content as well as in the incidence of hole with or without worm in chestnut fruit. Following sensory evaluation, 57% of panelist marked differences among treatments, while the greater preference (67%) observed in chestnut treated with HS and stored in MA. Additionally, MA-HS enhanced (up to 30%) the chestnut appearance while no difference observed in aroma, sweetness and texture among treatments and storage conditions. Thus, the impacts of HS on chestnuts maintain fruit quality, with benefits in CA storage, as increased panelists’ preference.
基金supported by National Natural Science Foundation of China under grant No.59374160.
文摘A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-low oxygen sensor. Especially, it is very sensitive to measure ultra-low oxygen in molten metal. For estimating the accuracy of La beta -Al2O3 oxygen sensor, two series of oxygen activities in molten iron at different oxygen contents and different temperature were measured by both La beta -Al2O3 oxygen sensor and ZrO2 oxygen sensor. The theoretical values of oxygen activities in molten iron (3.30%C, in mass fraction) at 1723K and 1745K were also evaluated for comparing the measuring results of two sensors. At last, the error of measurement for La beta -Al2O3 oxygen sensor was discussed too.
文摘为提高超低碳IF钢连铸可浇性和洁净度,开展了转炉底吹工艺优化、终点碳氧含量控制、顶渣改质、真空高效深脱碳技术和连铸保护浇铸工艺试验研究。结果表明:采用环缝式风口替代原有毛细管式透气砖底吹,转炉后期单管底吹强度0.086 m 3/(t·min),搅拌能0.40 W/t,能显著提高吹炼后期搅拌能力,转炉终点钢水平均碳氧积达0.00209。通过RH快速抽真空至极限真空度,3~5 min强制吹氧和8~12 min极限真空度下脱碳效率最高。降低真空脱碳后钢水残余氧含量、优化钢包顶渣成分,可显著减少Al 2 O 3夹杂物的产生,促进顶渣对夹杂物的吸附和溶解,配合连铸保护浇铸,钢水可浇性和氧化物夹杂控制水平明显提升。
基金Item Sponsored by National Basic Research Program of China(2010CB630806)
文摘The influence of calcium treatment on non-metallic inclusions had been studied when control technology of refining top slag in ladle furnace was used in ultra-low oxygen steelmaking. A sufficient amount aluminium was added to experimental heats for final deoxidizing during BOF tapping, and the refining top slag with strong reducibility, high basicity and high Al2O3 in ladle furnace was used to produce ultra-low oxygen steel and the transformation of nonmetallic inclusions in molten steel was compared by calcium treatment and no calcium treatment. The results show that the transformation of Al2O3--MgO - Al2O3 spinel-CaO-MgO-Al2O3 complex inclusions has been completed for aluminum deoxidation products and calcium treatment to molten steel is unnecessary when using the control technology of ladle furnace refining top slag to produce ultra-low oxygen steel, and the complex inclusions are liquid at the temperature of steelmaking and easily removable to obtain very high cleanliness steel by flotation. Further- more, the problems of nozzle clogging in casting operations do not happen and the remaining oxide inclusions in steel are the relatively lower melting point complex inclusions.
