Cooling rate is a key factor that can drastically affect the phase transformation and thermal stress of duplex stainless steels. Therefore, in this research, different sand moulds were used to explore the influence of...Cooling rate is a key factor that can drastically affect the phase transformation and thermal stress of duplex stainless steels. Therefore, in this research, different sand moulds were used to explore the influence of cooling rate on the solidification of the 2304 duplex stainless steel (DSS). The macro and micro structures of the 2304 DSS were investigated. Small equiaxed grains are obtained in chromite sand mould sample with a lower pouring temperature and a higher cooling rate, whereas coarse columnar and equiaxed grains are found in silica sand and refractory powder mould samples. The size of austenite phase is significantly increased with decreasing cooling rate, while the ferrite phase content ranging from 51.6% to 53.9% does not change obviously. In addition, the linear contraction of the 2304 DSS decreases from 2.34% to 1.09% when the mean cooling rate above 1,173 K increases from 0.99 K·s-1 to 3.66 K·s-1.展开更多
Traditional asphalt rejuvenators,like aromatic oil(AO),are known to be effective in improving the low-temperature properties and fatigue performances of aged SBS(styrene-butadiene-styrene)modified asphalt(SBSMA)binder...Traditional asphalt rejuvenators,like aromatic oil(AO),are known to be effective in improving the low-temperature properties and fatigue performances of aged SBS(styrene-butadiene-styrene)modified asphalt(SBSMA)binders and mixtures.However,these rejuvenators inevitably compromise their high-temperature properties and deformation resistances because they dilute asphalt binder but do not fix the damaged structures of aged SBS.In this study,a highly-active chemical called polymerized 4,4-diphenylmethane diisocyanate(PMDI)was used to assist the traditional AO asphalt rejuvenator.The physical and rheological characteristics of rejuvenated SBSMA binders and the moisture-induced damage and rut deformation performances of corresponding mixtures were comparatively evaluated.The results showed that the increasing proportion of AO compromises the hightemperature property and hardness of aged SBSMA binder,and an appropriate amount of PMDI works to compensate such losses;3%rejuvenator at mass ratio of AO:PMDI=70:30 can have a rejuvenated SBSMA binder with a high-temperature performance similar to that of fresh binder,approximately at 71.4°C;the use of AO can help reduce the viscosity of PMDI rejuvenated SBSMA binder for improving its workability;PMDI can help improve the resistance of AO rejuvenated SBSMA binder to deformation,especially at elevated temperatures,through its chemical reactions with aged SBS;moisture induction can enhance the resistance to damage of rejuvenated mixtures containing AO/PMDI or only PMDI;and the rejuvenator with a mass ratio of AO:PMDI=70:30 can lead the rejuvenated mixture to meet the application requirement,with a rut depth of only 2.973 mm,although more PMDI can result in a higher resistance of rejuvenated mixtures to high-temperature deformation.展开更多
Conventional repairing methods for asphalt pavement have some inconveniences,such as insufficient strength,and are typically time-consuming.To address these issues,this study proposes a new technological method to des...Conventional repairing methods for asphalt pavement have some inconveniences,such as insufficient strength,and are typically time-consuming.To address these issues,this study proposes a new technological method to design and prepare a high-performance assembled asphalt concrete block for fast repair of the potholes.A series of composite modified asphalt binders with 10%crumb rubber(CR)and different dosages(0%,1%,3%,5%)of polyurethane(PU)are examined to determine the optimized binder.Subsequently,the corresponding asphalt mixtures are prepared for further comparison and assessment of engineering properties,such as moistureinduced damage,high-temperature deformation,and low-temperature cracking characteristics.The test results show that PU can significantly improve the high-temperature performance and hardness of(crumb rubber modified asphalt)CRMA binder;3%PU contributes allowing the resistance of CRMA mixture to moisture-induced damage at higher levels,particularly under water whole immersion;as 3%PU is added,the high-temperature rutting deformation resistance of the CRMA mixture increases significantly,and the low-temperature anti-cracking properties are also improved slightly.Therefore,the innovatively designed high-quality assembled fast-repairing asphalt concrete block is recommended as an appropriate option for highway maintenance.展开更多
In rice(Oryza sativa),defects in endosperm development can give grains a chalky texture,which decreases grain quality and is thus undesirable for breeding and marketing.However,the molecular basis of chalki-ness remai...In rice(Oryza sativa),defects in endosperm development can give grains a chalky texture,which decreases grain quality and is thus undesirable for breeding and marketing.However,the molecular basis of chalki-ness remains largely unknown.Here,we identified CHALK10,which encodes an F-box protein that nega-tively regulates rice chalkiness.The chalk10 mutant exhibited abnormal starch granule development,decreased starch content,and altered starch physicochemical properties compared with the wild type.CHALK10 interacts with the gibberellin(GA)oxidase SEMIDWARF-1(SD1)and promotes the ubiquitination and degradation of SD1 through the 26S proteasome pathway.The grains of SD1-overexpressing plants ex-hibited increased chalkiness;introduction of the sd1 mutant allele into the chalk10 background largely sup-pressed the enhanced chalkiness observed in the chalk10 mutant.GA levels were higher in the chalk10 mutant than in the wild type,and application of the bioactive GA form GA3 increased grain chalkiness.The expression of genes related to starch degradation or biosynthesis was altered in the chalk10 mutant,resulting in reduced starch production and increased metabolizable sugar content in the endosperm.In summary,our findings reveal a novel regulatory mechanism of chalkiness and provide potential targets for improving rice quality.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 50904044)
文摘Cooling rate is a key factor that can drastically affect the phase transformation and thermal stress of duplex stainless steels. Therefore, in this research, different sand moulds were used to explore the influence of cooling rate on the solidification of the 2304 duplex stainless steel (DSS). The macro and micro structures of the 2304 DSS were investigated. Small equiaxed grains are obtained in chromite sand mould sample with a lower pouring temperature and a higher cooling rate, whereas coarse columnar and equiaxed grains are found in silica sand and refractory powder mould samples. The size of austenite phase is significantly increased with decreasing cooling rate, while the ferrite phase content ranging from 51.6% to 53.9% does not change obviously. In addition, the linear contraction of the 2304 DSS decreases from 2.34% to 1.09% when the mean cooling rate above 1,173 K increases from 0.99 K·s-1 to 3.66 K·s-1.
基金supported by the Scientific Technology R&D Project of CCCC Asset Management Co.,Ltd.(RP2022015294).
文摘Traditional asphalt rejuvenators,like aromatic oil(AO),are known to be effective in improving the low-temperature properties and fatigue performances of aged SBS(styrene-butadiene-styrene)modified asphalt(SBSMA)binders and mixtures.However,these rejuvenators inevitably compromise their high-temperature properties and deformation resistances because they dilute asphalt binder but do not fix the damaged structures of aged SBS.In this study,a highly-active chemical called polymerized 4,4-diphenylmethane diisocyanate(PMDI)was used to assist the traditional AO asphalt rejuvenator.The physical and rheological characteristics of rejuvenated SBSMA binders and the moisture-induced damage and rut deformation performances of corresponding mixtures were comparatively evaluated.The results showed that the increasing proportion of AO compromises the hightemperature property and hardness of aged SBSMA binder,and an appropriate amount of PMDI works to compensate such losses;3%rejuvenator at mass ratio of AO:PMDI=70:30 can have a rejuvenated SBSMA binder with a high-temperature performance similar to that of fresh binder,approximately at 71.4°C;the use of AO can help reduce the viscosity of PMDI rejuvenated SBSMA binder for improving its workability;PMDI can help improve the resistance of AO rejuvenated SBSMA binder to deformation,especially at elevated temperatures,through its chemical reactions with aged SBS;moisture induction can enhance the resistance to damage of rejuvenated mixtures containing AO/PMDI or only PMDI;and the rejuvenator with a mass ratio of AO:PMDI=70:30 can lead the rejuvenated mixture to meet the application requirement,with a rut depth of only 2.973 mm,although more PMDI can result in a higher resistance of rejuvenated mixtures to high-temperature deformation.
基金the Scientific Technology R&D Project of CCCC Asset Management Co.,Ltd.(RP2022015294&RP2022015296).
文摘Conventional repairing methods for asphalt pavement have some inconveniences,such as insufficient strength,and are typically time-consuming.To address these issues,this study proposes a new technological method to design and prepare a high-performance assembled asphalt concrete block for fast repair of the potholes.A series of composite modified asphalt binders with 10%crumb rubber(CR)and different dosages(0%,1%,3%,5%)of polyurethane(PU)are examined to determine the optimized binder.Subsequently,the corresponding asphalt mixtures are prepared for further comparison and assessment of engineering properties,such as moistureinduced damage,high-temperature deformation,and low-temperature cracking characteristics.The test results show that PU can significantly improve the high-temperature performance and hardness of(crumb rubber modified asphalt)CRMA binder;3%PU contributes allowing the resistance of CRMA mixture to moisture-induced damage at higher levels,particularly under water whole immersion;as 3%PU is added,the high-temperature rutting deformation resistance of the CRMA mixture increases significantly,and the low-temperature anti-cracking properties are also improved slightly.Therefore,the innovatively designed high-quality assembled fast-repairing asphalt concrete block is recommended as an appropriate option for highway maintenance.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(LDQ24C130001)the National Natural Science Foundation of China(32188102),a Zhejiang Provincial Science and Tech-nology Project(2020R51007)+2 种基金the Key Research and Development Pro-gram of Zhejiang Province(2022C02011)the Innovation Program of Chi-nese Academy of Agricultural Sciences(No.CAAS-CSCB-202402)the Central Public-interest Scientific Institution Basal Research Fund(No.CPSIBRF-CNRRI-202403).
文摘In rice(Oryza sativa),defects in endosperm development can give grains a chalky texture,which decreases grain quality and is thus undesirable for breeding and marketing.However,the molecular basis of chalki-ness remains largely unknown.Here,we identified CHALK10,which encodes an F-box protein that nega-tively regulates rice chalkiness.The chalk10 mutant exhibited abnormal starch granule development,decreased starch content,and altered starch physicochemical properties compared with the wild type.CHALK10 interacts with the gibberellin(GA)oxidase SEMIDWARF-1(SD1)and promotes the ubiquitination and degradation of SD1 through the 26S proteasome pathway.The grains of SD1-overexpressing plants ex-hibited increased chalkiness;introduction of the sd1 mutant allele into the chalk10 background largely sup-pressed the enhanced chalkiness observed in the chalk10 mutant.GA levels were higher in the chalk10 mutant than in the wild type,and application of the bioactive GA form GA3 increased grain chalkiness.The expression of genes related to starch degradation or biosynthesis was altered in the chalk10 mutant,resulting in reduced starch production and increased metabolizable sugar content in the endosperm.In summary,our findings reveal a novel regulatory mechanism of chalkiness and provide potential targets for improving rice quality.
