Shear thickening fluids （STFs） based on additives with different concentrations and molecular chain lengths were investigated. STF samples were prepared with silica and additive dispersed in polyethylene glycol （PE...Shear thickening fluids （STFs） based on additives with different concentrations and molecular chain lengths were investigated. STF samples were prepared with silica and additive dispersed in polyethylene glycol （PEG） 400, where three types of additives with different molecular chain lengths of PEG4000, PEG6000, and PEG10000 were used. For PEG10000, different concentrations, including 0, 1%, 3%, and 5%, were selected to study the influences of additive concentrations. Rheological properties of the samples were measured with a rheometer. The results show that the shear thickening effect was significantly enhanced with the increase of the concentration and the molecular chain length of additives. The mechanism of enhancement was quantitatively explained with the formation of large particles clusters.展开更多
Additive manufacturing(AM)is an innovative technology that creates objects with a complex geometry layer-by-layer,and it has rapidly prospered in manufacturing metallic parts for structural and functional applications...Additive manufacturing(AM)is an innovative technology that creates objects with a complex geometry layer-by-layer,and it has rapidly prospered in manufacturing metallic parts for structural and functional applications.Recent literatures have investigated the effect of different AM technologies on the microstructure evolution of titanium alloys.However,metal AM has mostly been regarded only as a shaping technology for near-net-shape manufacturing.A huge advantage of AM in alloy design and treatments has been largely overlooked at the present time.In this paper,we systematically reviewed the interaction of AM processes and different Ti-alloys,as well as the possible ways for mechanical property enhancements.On the one hand,the complex thermal histories caused by AM influence the phase transformation of Ti-alloys.On the other hand,the unique thermal and processing features of AM provide ways and opportunities to design new Ti-alloys with unachievable microstructures and properties by conventional methods.The aim of this paper is thus to provide a new perspective on the relationship between the AM process and alloy design,which is to consider AM as an irreplaceable material treating and design method.Only an integrated consideration of both AM process and alloy design can successfully achieve materials with superior properties for applications in the future industries.展开更多
Aims We explored the decomposition rates of single-and mixed-species litter,the litter-mixing effect and the effect of component litters in a mixture on decomposition.Methods In a litter bag experiment,shoot litters f...Aims We explored the decomposition rates of single-and mixed-species litter,the litter-mixing effect and the effect of component litters in a mixture on decomposition.Methods In a litter bag experiment,shoot litters from two dominant grasses(Leymus chinensis and Stipa baicalensis)and one legume(Melissitus ruthenica)were decomposed separately and as a mixture from May 2010 to September 2011 in the Hulun Buir meadow steppe of Inner Mongolia,China.We separated the litter mixture into its individual component litters(i.e.the different single-species litters)and analyzed the changes in litter mass remaining and litter nitrogen(N)remaining during single-and mixed-species litter decomposition.Important Findings(i)Litter mixing had significant positive effects on litter decomposition.The litter-mixing effect was strongest for the mixture of S.baicalensis and L.chinensis litters,followed by the mixture of S.baicalensis and M.ruthenica litters.(ii)Single-species component litters decomposed faster in the mixtures than separately(positive effect),but these effects were not significant for legume species M.ruthenica litter.Relative to single-species litter decomposition,the decomposition rates of the two grass(S.baicalensis and L.chinensis)litters significantly increased when they were mixed with each other or with M.ruthenica litter.(iii)For each species litter type,the percentage of litter N remaining during decomposition(NR)differed between the single-species litter and mixed litter treatments.The NR of S.baicalensis litter was higher when it was decomposed in the mixture than in isolation.However,the NR of L.chinensis litter was lowest in its mixture with M.ruthenica among the treatments.Regardless of its decomposition in the mixture or in isolation,the NR of M.ruthenica litter varied little among treatments.There was a significant positive relationship between the NR and percentage of initial litter mass remaining in both the single litter and mixed litter treatments.These results suggest that N transfer may happen amon展开更多
文摘Shear thickening fluids （STFs） based on additives with different concentrations and molecular chain lengths were investigated. STF samples were prepared with silica and additive dispersed in polyethylene glycol （PEG） 400, where three types of additives with different molecular chain lengths of PEG4000, PEG6000, and PEG10000 were used. For PEG10000, different concentrations, including 0, 1%, 3%, and 5%, were selected to study the influences of additive concentrations. Rheological properties of the samples were measured with a rheometer. The results show that the shear thickening effect was significantly enhanced with the increase of the concentration and the molecular chain length of additives. The mechanism of enhancement was quantitatively explained with the formation of large particles clusters.
基金the internal funding from City University of Hong Kong under the Programs 9042635 and 9360161.
文摘Additive manufacturing(AM)is an innovative technology that creates objects with a complex geometry layer-by-layer,and it has rapidly prospered in manufacturing metallic parts for structural and functional applications.Recent literatures have investigated the effect of different AM technologies on the microstructure evolution of titanium alloys.However,metal AM has mostly been regarded only as a shaping technology for near-net-shape manufacturing.A huge advantage of AM in alloy design and treatments has been largely overlooked at the present time.In this paper,we systematically reviewed the interaction of AM processes and different Ti-alloys,as well as the possible ways for mechanical property enhancements.On the one hand,the complex thermal histories caused by AM influence the phase transformation of Ti-alloys.On the other hand,the unique thermal and processing features of AM provide ways and opportunities to design new Ti-alloys with unachievable microstructures and properties by conventional methods.The aim of this paper is thus to provide a new perspective on the relationship between the AM process and alloy design,which is to consider AM as an irreplaceable material treating and design method.Only an integrated consideration of both AM process and alloy design can successfully achieve materials with superior properties for applications in the future industries.
基金The work was carried out in the Hulun Buir meadow steppe of Inner Mongolia,ChinaNational Basic Research Program of China(2010CB833501,973 Program)National Major Research Program of China on Climate Change(2010CB950603).
文摘Aims We explored the decomposition rates of single-and mixed-species litter,the litter-mixing effect and the effect of component litters in a mixture on decomposition.Methods In a litter bag experiment,shoot litters from two dominant grasses(Leymus chinensis and Stipa baicalensis)and one legume(Melissitus ruthenica)were decomposed separately and as a mixture from May 2010 to September 2011 in the Hulun Buir meadow steppe of Inner Mongolia,China.We separated the litter mixture into its individual component litters(i.e.the different single-species litters)and analyzed the changes in litter mass remaining and litter nitrogen(N)remaining during single-and mixed-species litter decomposition.Important Findings(i)Litter mixing had significant positive effects on litter decomposition.The litter-mixing effect was strongest for the mixture of S.baicalensis and L.chinensis litters,followed by the mixture of S.baicalensis and M.ruthenica litters.(ii)Single-species component litters decomposed faster in the mixtures than separately(positive effect),but these effects were not significant for legume species M.ruthenica litter.Relative to single-species litter decomposition,the decomposition rates of the two grass(S.baicalensis and L.chinensis)litters significantly increased when they were mixed with each other or with M.ruthenica litter.(iii)For each species litter type,the percentage of litter N remaining during decomposition(NR)differed between the single-species litter and mixed litter treatments.The NR of S.baicalensis litter was higher when it was decomposed in the mixture than in isolation.However,the NR of L.chinensis litter was lowest in its mixture with M.ruthenica among the treatments.Regardless of its decomposition in the mixture or in isolation,the NR of M.ruthenica litter varied little among treatments.There was a significant positive relationship between the NR and percentage of initial litter mass remaining in both the single litter and mixed litter treatments.These results suggest that N transfer may happen amon
