To determine the modifying agents for Al-7Si alloys, microstructure observation and mixing enthalpy analysis using Miedema model for Al-7Si alloy with additions of different rare earth elements were performed, and the...To determine the modifying agents for Al-7Si alloys, microstructure observation and mixing enthalpy analysis using Miedema model for Al-7Si alloy with additions of different rare earth elements were performed, and the effects of rare earth elements on the modifica-tion of eutectic silicon morphology were investigated. The results of mixing enthalpy analysis show that these four rare earth elements, La, Sm, Pr, and Ce, which have the large negative mixing enthalpies with Si, can be selected as modifying agents for eutectic silicon morphology. The element with the largest negative mixing enthalpy is Ce. Furthermore, the microstructures indicate that these four elements can effec-tively modify the eutectic (α)Al-Si crystals in Al-7Si alloy, and the most effective one is also Ce. Differential scanning calorimetry (DSC) results show that the eutectic temperature depressions due to the additions of modifying agents are the important reasons for the modification of eutectic (α)Al-Si crystals.展开更多
Harmless rare-earth modifying agents were prepared by orthogonal experiments. A new resin material was synthesized with the qualities such as rigidity, rubbing abrasion, aging, luster and plasticity better than the de...Harmless rare-earth modifying agents were prepared by orthogonal experiments. A new resin material was synthesized with the qualities such as rigidity, rubbing abrasion, aging, luster and plasticity better than the dental resin materials in common used. It could be used as the substitutes for the applied resin teeth materials.展开更多
Preparation of high acidity coefficient slag wool fiber with molten slag and modifying agents is considered to be a positive approach for value-added utilization of blast furnace slag. In order to achieve the multi-pu...Preparation of high acidity coefficient slag wool fiber with molten slag and modifying agents is considered to be a positive approach for value-added utilization of blast furnace slag. In order to achieve the multi-purposes of fiber-forming, energy saving, and waste heat recovery, the modifying agents that can improve the acidity coefficient of slag effectively, economically, and environmentally were investigated. Three agents with different acidity coefficients were adopted to modify slag and manufacture wool fibers. The effect of agent and slag proportion on the melting temperature and viscosity of molten slag was studied at a fixed acidity coefficient of 1.8 and 2.0. The results indicate that the sample modified with high acidity coefficient agent and high slag proportion has lower melting temperature and viscosity. The effect of agent and slag temperature on the fiber diameter was also investigated when the acidity coefficient of slag is 2.0. At a fixed slag proportion of 50 wt.%, the mean diameter decreases with increasing temperature and decreasing viscosity coefficient. Besides, the temperature drops caused by the addition of agents and energy consumption of samples for heating the slag were also analyzed.展开更多
In a world of increasing resistance to current antibiotics,search of novel therapeutic options is urgently needed.The aim of this work was to screen plant crude extracts for direct or indirect(inhibition of resistance...In a world of increasing resistance to current antibiotics,search of novel therapeutic options is urgently needed.The aim of this work was to screen plant crude extracts for direct or indirect(inhibition of resistance)antimicrobial activity.Four crude extracts from 12 plants traditionally used in Benin for the treatment of infections were展开更多
For lack of laboratory and field performance data on stabilization of reclaimed asphalt pavement (RAP) aggregate and stabilized soil (S) for road bases and subbases construction, the influences of RAP/S ratio, cem...For lack of laboratory and field performance data on stabilization of reclaimed asphalt pavement (RAP) aggregate and stabilized soil (S) for road bases and subbases construction, the influences of RAP/S ratio, cement and fly ash content, modifying agent (MA) on the compact, unconfined compressive strength, indirect tensile strength and water stability of the CIR mixtures were investigated. The experimental results showed that the maximum dry density and the optimum moisture content of the mixture changed significantly with the RAP/S ratio and cement-fly ash content. Unconfined compressive strength, indirect tensile strength and water stability were improved significantly by the addition of MA, and the water stability was improved by nearly 20% on average. Scanning electron microscopy(SEM) images indicated that MA accelerated the hydration of cement-fly ash system. Needle-like AFt and fibrous C-S-H gel were observed in the mixtures, which resulted in the cementation effect among the CIR mixture particles and a more compact microstructure. All these could be the cause of high strength of the CIR mixtures with MA.展开更多
基金supported by the Research Fund of the State Key Laboratory of Solidification Processing (No.42-QP-009)the Open Fund of the State Key Laboratory of Solidification Processing in NWPU (No.201009)+1 种基金the Fundamental Research Fund of Northwestern Polytechnical University (No.JC200929)the 111 Project of China (No.B08040)
文摘To determine the modifying agents for Al-7Si alloys, microstructure observation and mixing enthalpy analysis using Miedema model for Al-7Si alloy with additions of different rare earth elements were performed, and the effects of rare earth elements on the modifica-tion of eutectic silicon morphology were investigated. The results of mixing enthalpy analysis show that these four rare earth elements, La, Sm, Pr, and Ce, which have the large negative mixing enthalpies with Si, can be selected as modifying agents for eutectic silicon morphology. The element with the largest negative mixing enthalpy is Ce. Furthermore, the microstructures indicate that these four elements can effec-tively modify the eutectic (α)Al-Si crystals in Al-7Si alloy, and the most effective one is also Ce. Differential scanning calorimetry (DSC) results show that the eutectic temperature depressions due to the additions of modifying agents are the important reasons for the modification of eutectic (α)Al-Si crystals.
基金Project surported bythe NationaI NaturaI Science Foundation of China (50164001)
文摘Harmless rare-earth modifying agents were prepared by orthogonal experiments. A new resin material was synthesized with the qualities such as rigidity, rubbing abrasion, aging, luster and plasticity better than the dental resin materials in common used. It could be used as the substitutes for the applied resin teeth materials.
基金the National Natural Science Foundation of China(Grant No.51974054)Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJQN202201537)+2 种基金Research Foundation of Chongqing University of Science and Technology(No.ckrc2020017)Natural Science Foundation Project of Chongqing(No.cstc2021jcyj-msxmX0911)Chongqing Science and Technology Commission(No.sl202100000144).
文摘Preparation of high acidity coefficient slag wool fiber with molten slag and modifying agents is considered to be a positive approach for value-added utilization of blast furnace slag. In order to achieve the multi-purposes of fiber-forming, energy saving, and waste heat recovery, the modifying agents that can improve the acidity coefficient of slag effectively, economically, and environmentally were investigated. Three agents with different acidity coefficients were adopted to modify slag and manufacture wool fibers. The effect of agent and slag proportion on the melting temperature and viscosity of molten slag was studied at a fixed acidity coefficient of 1.8 and 2.0. The results indicate that the sample modified with high acidity coefficient agent and high slag proportion has lower melting temperature and viscosity. The effect of agent and slag temperature on the fiber diameter was also investigated when the acidity coefficient of slag is 2.0. At a fixed slag proportion of 50 wt.%, the mean diameter decreases with increasing temperature and decreasing viscosity coefficient. Besides, the temperature drops caused by the addition of agents and energy consumption of samples for heating the slag were also analyzed.
文摘In a world of increasing resistance to current antibiotics,search of novel therapeutic options is urgently needed.The aim of this work was to screen plant crude extracts for direct or indirect(inhibition of resistance)antimicrobial activity.Four crude extracts from 12 plants traditionally used in Benin for the treatment of infections were
基金Funded by the High-Tech Research and Development Program (863 National Program) of China(No.2009AA11Z106)
文摘For lack of laboratory and field performance data on stabilization of reclaimed asphalt pavement (RAP) aggregate and stabilized soil (S) for road bases and subbases construction, the influences of RAP/S ratio, cement and fly ash content, modifying agent (MA) on the compact, unconfined compressive strength, indirect tensile strength and water stability of the CIR mixtures were investigated. The experimental results showed that the maximum dry density and the optimum moisture content of the mixture changed significantly with the RAP/S ratio and cement-fly ash content. Unconfined compressive strength, indirect tensile strength and water stability were improved significantly by the addition of MA, and the water stability was improved by nearly 20% on average. Scanning electron microscopy(SEM) images indicated that MA accelerated the hydration of cement-fly ash system. Needle-like AFt and fibrous C-S-H gel were observed in the mixtures, which resulted in the cementation effect among the CIR mixture particles and a more compact microstructure. All these could be the cause of high strength of the CIR mixtures with MA.