The effect of applied tensile stress on the r'-rafting behavior for a Ni-based single-crystal superalloy with more negative misfit was investigated.By conducting interrupted creep tests at high temperature,it indi...The effect of applied tensile stress on the r'-rafting behavior for a Ni-based single-crystal superalloy with more negative misfit was investigated.By conducting interrupted creep tests at high temperature,it indicated that the increase in the applied stress accelerates the r'-rafting(directional coarsening of yr phase).In the early stage of rafting,the r'-cubes start interconnecting at the ends of the parallel-to-applied-stress r'-channel.The distributions of misfit stress,coherent strain and strain energy density of the r/r'phases are then calculated by finite element analysis.The calculation results show that the rafting acceleration is mainly ascribed to the reduced strain energy density in the parallel-to-applied-stress r'-channel that is driven from the couple interaction of external load and misfit stress.Interface dislocation network formation,resulting from the misfit-induced increase in resolved shear stress,also contributes to the r'-rafting.展开更多
An anisotropic micromechanics model based on the equivalent inclusion method is developed to investigate the rafting direction of Ni-based single crystal superalloys. The micromechanical model considers actual cubic s...An anisotropic micromechanics model based on the equivalent inclusion method is developed to investigate the rafting direction of Ni-based single crystal superalloys. The micromechanical model considers actual cubic structure and orthogonal anisotropy properties. The von Mises stress, elastic strain energy density, and hydrostatic pressure in dif- ferent inclusions of micromechanical model are calculated when applying a tensile or compressive loading along the [001] direction. The calculated results can successfully pre- dict the rafting direction for alloys exhibiting a positive or a negative mismatch, which are in agreement with pervious experimental and theoretical studies. Moreover, the elastic constant differences and mismatch degree of the matrix and precipitate phases and their influences on the rafting direction are carefully discussed.展开更多
The functional regeneration of damaged axons and severed connections in the mature central nervous sys- tem （CNS） remains a challenging goal of neurological research. Mature CNS neurons are refractory to axon regene...The functional regeneration of damaged axons and severed connections in the mature central nervous sys- tem （CNS） remains a challenging goal of neurological research. Mature CNS neurons are refractory to axon regeneration for two major reasons, one, because the ac- tivity of cell-intrinsic mechanisms that drive axon growth during development is low- and often further suppressed after an injury - and two, because certain molecules that are part of mature extracellular matrix and myelin act as strong inhibitors of axon growth. Genetic removal of growth inhibitory molecules can increase axon sprouting, but is not sufficient to enable long-range axon growth. Since axon growth is robust during early developmental stages, it has long been hypothesized that mature injured neurons may be ＂reprogrammed＂ to the earlier growth state by re-activation of the intracellular growth signaling cascades that drive axon elongation in the developing fetus.展开更多
The success of each enterprise is finding, working on it, promoting, and obviously offering what the consumers really love and enjoy. Albania is very useful if you have this mission： Reconciling all the nature compon...The success of each enterprise is finding, working on it, promoting, and obviously offering what the consumers really love and enjoy. Albania is very useful if you have this mission： Reconciling all the nature components with favorable weather conditions, we can really offer an adventure business, where everyone can discover the beauty of Albania through an unforgettable trip. The key word that summarizes all the elements mentioned is without a doubt “Rafting”. Introducing rafting both as a sport and as a touristic outdoor activity, in that way we develop a new touristic market and a strong promoter of sustainable adventure tourism in Albania. When a person takes pleasure but in an unhealthy extent, how does this affect his personality？ The adrenaline as happiness, meaning and pleasure…The topics that this study is about, are two key terms that will guarantee the success of this “adventure project”： The first is the satisfaction of consumers, which gives us a feedback about the product/service and the second part deals with the term adrenaline （pleasure supreme customer）; hedonic consumer features, part of their character, the main approaches and a study conducted with customers who have attended at least once rafting, customers attending characteristic of emotions, adrenaline, and adventure to take the pleasure of life. A company should always try and please its consumers. Usually, pleased consumers will always come back for more; they will also spread the word and bring new potential consumers into your business that will pay a fair amount of money for a new upcoming product that set company offers. The measurement of consumer satisfaction is a pure indicator of the consumers repurchases intentions, an indicator of the actual performance and differentiation from the current competition. The consumers mind will always remember the name of the company that they had a bad experience rather than the onethey have been satisfied with. Often when we receive a fixed service, our mind tends to create a very close emotional connection to set service. Often we find that the smallest things bring the greatest joy, regardless of the price. For the majority part, following the adrenaline passion is more than just a need. Lately, the traditional notion of purchasing is left behind and everyone is focusing on providing themselves with pleasure and emotions. The definition of the word “hedonic” comes from Ancient Greece, meaning “taking the maximal pleasure from life” being our primary goal.展开更多
Multiproxy investigations have been performed on Core 08P23 collected from the Chukchi Plateau, the western Arctic Ocean, during the Third Chinese National Arctic Expedition. The core was dated back to Ma-rine Isotope...Multiproxy investigations have been performed on Core 08P23 collected from the Chukchi Plateau, the western Arctic Ocean, during the Third Chinese National Arctic Expedition. The core was dated back to Ma-rine Isotope Stage （MIS） 3 by a combination of Accelerator Mass Spectrometric （AMS） carbon-14 dating and regional core correlation. A total of five prominent ice-rafted detritus （IRD） events were recognized in MIS 2 and MIS 3. The IRD sources in MIS 3 are originated from vast carbonate rock outcrops of the Canadian Arctic Archipelago and clastic quartz in MIS 2 may have a Eurasian origin. Mostδ18O andδ13C values of Neogloboquadrina pachyderma （sinistral） （Nps） in Core 08P23 are lighter than the average values of surface sediments. The lighterδ18O andδ13C values of Nps in the two brown layers in MIS 1 and MIS 3 were resulted from meltwater events; and those in the gray layers in MIS 3 were caused by the enhanced sea ice formation. Theδ18O values varied inversely withδ13C in MIS 2 indicate that the study area was covered by thick sea ice or ice sheet with low temperature and little meltwater, which prevented the biological productivity and sea-atmosphere exchange, as well as water mass ventilation. The covaried light values ofδ18O andδ13C in MIS 1 and MIS 3 were resulted from meltwater and/or brine injection.展开更多
Theoretical analysis and numerical simulation have been applied to researching the effect of wave,current and wind on the ice rafting.The analytical results show that wave is the key factor for ice fracture.The proces...Theoretical analysis and numerical simulation have been applied to researching the effect of wave,current and wind on the ice rafting.The analytical results show that wave is the key factor for ice fracture.The process of ice rafting is simulated using the discrete element method.The simulated results show that the distortion or flexure breakage happens firstly,then followed by ice rafting.The comprehensively analysed results show that the ice is easily rafted on the simultaneity action of wave,current and wind,and the action of wave can＇t be ignored.Moreover,the rafted ice length increases with the enhancive force of ocean current and wind.展开更多
Organic/inorganic hybrid polymers have been widely studied for their potential use in nanocontainers and nanocarriers. In this article, one star-shaped hybrid polymer, polyhedral oligomeric silsesquioxane （POSS） gra...Organic/inorganic hybrid polymers have been widely studied for their potential use in nanocontainers and nanocarriers. In this article, one star-shaped hybrid polymer, polyhedral oligomeric silsesquioxane （POSS） grafted poly（N,N-（dimethylamino）ethyl methacrylate） （POSS-g-PDMA）, was synthesized via reversible addition-fragmentation chain transfer polymerization （RAFT）. The pH stimuli-responsive character of POSS-g-PDMA in aqueous solution were also studied.展开更多
Microstructural rafting of Ni-based single-crystal(SC) superalloys is inevitable at elevated temperatures during long-term service with mechanical loading, which significantly affects the mechanical behaviour of the m...Microstructural rafting of Ni-based single-crystal(SC) superalloys is inevitable at elevated temperatures during long-term service with mechanical loading, which significantly affects the mechanical behaviour of the material. In this study, the effects of rafting on the mesodeformation and fracture behaviour of a Ni-based SC superalloy under cyclic and tensile loads were investigated using in situ scanning electron microscopy(SEM), digital image correlation(DIC), and crystal plasticity finite element method(CP-FEM) simulations. The results indicated that the tensile strength decreased significantly in the rafted specimens. In the cyclic tests, both the virgin and rafted specimens showed an increase in the maximum shear strain with cycle number. The interaction of cross-slip bands was captured by in situ SEM-DIC around the micro-notch of the virgin specimens during the tensile test, while a more homogeneous local deformation field was observed in the rafting specimens. In addition,the fracture behaviour was strongly influenced by the rafting morphology. The crack exhibited instantaneous and long-range fracture features along the octahedral plane as it propagated in the rafting specimen, whereas it deflected over a short distance between the crystallographic planes at an early stage in the virgin specimen, which is consistent with the CP-FEM results.Furthermore, the CP-FEM results for the crack initiation direction on(111) dominant slip plane were consistent with the in situ SEM observations.展开更多
Thermomechanical Fatigue (TMF) is one of the most dangerous failure modes of high-temperature structures. The effect of coarsened and rafted microstructures on the TMF behavior of Nickel-Base Single Crystal Superalloy...Thermomechanical Fatigue (TMF) is one of the most dangerous failure modes of high-temperature structures. The effect of coarsened and rafted microstructures on the TMF behavior of Nickel-Base Single Crystal Superalloys (NBSX) was experimentally studied. TMF tests under In-Phase (IP) and Out-of-Phase (OP) paths revealed significant variations in TMF life reduction. Cyclic deformation behaviors of alloys with different microstructures were compared. The effect of microstructure on TMF damage mechanisms was unveiled from characterizations of fracture surfaces and longitudinal sections by scanning electronic microscope and optical microscope. A transition from mode-I to crystallographic fracture in the coarsened alloy during IP-TMF was observed and discussed. Due to the degraded microstructure, the dispersed distribution of crystal slips was distinguished in the coarsened and rafted alloys. The competitive or synergetic interactions among oxidation-assisted mode-I opening, casting pore-related mode-I creep and crystallographic slipping were discussed. This study underscores the complex interplay among microstructure, deformation behaviors and damage mechanisms, offering valuable insights into alloy performance under TMF conditions.展开更多
基金National Natural Science Foundation of China(Nos.U1435207,51771007,51671015)National Defense Basic Scientific Research Project(No.A2120132006).
文摘The effect of applied tensile stress on the r'-rafting behavior for a Ni-based single-crystal superalloy with more negative misfit was investigated.By conducting interrupted creep tests at high temperature,it indicated that the increase in the applied stress accelerates the r'-rafting(directional coarsening of yr phase).In the early stage of rafting,the r'-cubes start interconnecting at the ends of the parallel-to-applied-stress r'-channel.The distributions of misfit stress,coherent strain and strain energy density of the r/r'phases are then calculated by finite element analysis.The calculation results show that the rafting acceleration is mainly ascribed to the reduced strain energy density in the parallel-to-applied-stress r'-channel that is driven from the couple interaction of external load and misfit stress.Interface dislocation network formation,resulting from the misfit-induced increase in resolved shear stress,also contributes to the r'-rafting.
基金supported by The National Natural Science Foundation of China (Grants 11102139 and 11472195)The Natural Science Foundation of Hubei Province of China (Grant 2014CFB713)
文摘An anisotropic micromechanics model based on the equivalent inclusion method is developed to investigate the rafting direction of Ni-based single crystal superalloys. The micromechanical model considers actual cubic structure and orthogonal anisotropy properties. The von Mises stress, elastic strain energy density, and hydrostatic pressure in dif- ferent inclusions of micromechanical model are calculated when applying a tensile or compressive loading along the [001] direction. The calculated results can successfully pre- dict the rafting direction for alloys exhibiting a positive or a negative mismatch, which are in agreement with pervious experimental and theoretical studies. Moreover, the elastic constant differences and mismatch degree of the matrix and precipitate phases and their influences on the rafting direction are carefully discussed.
基金funding from the National Eye Institute (R01EY022409)the Craig H. Neilsen Foundation (296098)+2 种基金the Wings for Life Foundation (WFL-US-028/14)the New York State Spinal Cord Injury Research Trust Fundthe Burke Foundation
文摘The functional regeneration of damaged axons and severed connections in the mature central nervous sys- tem （CNS） remains a challenging goal of neurological research. Mature CNS neurons are refractory to axon regeneration for two major reasons, one, because the ac- tivity of cell-intrinsic mechanisms that drive axon growth during development is low- and often further suppressed after an injury - and two, because certain molecules that are part of mature extracellular matrix and myelin act as strong inhibitors of axon growth. Genetic removal of growth inhibitory molecules can increase axon sprouting, but is not sufficient to enable long-range axon growth. Since axon growth is robust during early developmental stages, it has long been hypothesized that mature injured neurons may be ＂reprogrammed＂ to the earlier growth state by re-activation of the intracellular growth signaling cascades that drive axon elongation in the developing fetus.
文摘The success of each enterprise is finding, working on it, promoting, and obviously offering what the consumers really love and enjoy. Albania is very useful if you have this mission： Reconciling all the nature components with favorable weather conditions, we can really offer an adventure business, where everyone can discover the beauty of Albania through an unforgettable trip. The key word that summarizes all the elements mentioned is without a doubt “Rafting”. Introducing rafting both as a sport and as a touristic outdoor activity, in that way we develop a new touristic market and a strong promoter of sustainable adventure tourism in Albania. When a person takes pleasure but in an unhealthy extent, how does this affect his personality？ The adrenaline as happiness, meaning and pleasure…The topics that this study is about, are two key terms that will guarantee the success of this “adventure project”： The first is the satisfaction of consumers, which gives us a feedback about the product/service and the second part deals with the term adrenaline （pleasure supreme customer）; hedonic consumer features, part of their character, the main approaches and a study conducted with customers who have attended at least once rafting, customers attending characteristic of emotions, adrenaline, and adventure to take the pleasure of life. A company should always try and please its consumers. Usually, pleased consumers will always come back for more; they will also spread the word and bring new potential consumers into your business that will pay a fair amount of money for a new upcoming product that set company offers. The measurement of consumer satisfaction is a pure indicator of the consumers repurchases intentions, an indicator of the actual performance and differentiation from the current competition. The consumers mind will always remember the name of the company that they had a bad experience rather than the onethey have been satisfied with. Often when we receive a fixed service, our mind tends to create a very close emotional connection to set service. Often we find that the smallest things bring the greatest joy, regardless of the price. For the majority part, following the adrenaline passion is more than just a need. Lately, the traditional notion of purchasing is left behind and everyone is focusing on providing themselves with pleasure and emotions. The definition of the word “hedonic” comes from Ancient Greece, meaning “taking the maximal pleasure from life” being our primary goal.
基金The National Natural Science Foundation of China under contract Nos 41030859,41211120173,CHINARE2015-03-02 and IC201105the Geological Investigation Project of China Geological Survey Nos 12120113006200 and 1212011120044
文摘Multiproxy investigations have been performed on Core 08P23 collected from the Chukchi Plateau, the western Arctic Ocean, during the Third Chinese National Arctic Expedition. The core was dated back to Ma-rine Isotope Stage （MIS） 3 by a combination of Accelerator Mass Spectrometric （AMS） carbon-14 dating and regional core correlation. A total of five prominent ice-rafted detritus （IRD） events were recognized in MIS 2 and MIS 3. The IRD sources in MIS 3 are originated from vast carbonate rock outcrops of the Canadian Arctic Archipelago and clastic quartz in MIS 2 may have a Eurasian origin. Mostδ18O andδ13C values of Neogloboquadrina pachyderma （sinistral） （Nps） in Core 08P23 are lighter than the average values of surface sediments. The lighterδ18O andδ13C values of Nps in the two brown layers in MIS 1 and MIS 3 were resulted from meltwater events; and those in the gray layers in MIS 3 were caused by the enhanced sea ice formation. Theδ18O values varied inversely withδ13C in MIS 2 indicate that the study area was covered by thick sea ice or ice sheet with low temperature and little meltwater, which prevented the biological productivity and sea-atmosphere exchange, as well as water mass ventilation. The covaried light values ofδ18O andδ13C in MIS 1 and MIS 3 were resulted from meltwater and/or brine injection.
基金The National Natural Science Foundation of China under contract Nos 40506009 and 908-02-03’ National Project
文摘Theoretical analysis and numerical simulation have been applied to researching the effect of wave,current and wind on the ice rafting.The analytical results show that wave is the key factor for ice fracture.The process of ice rafting is simulated using the discrete element method.The simulated results show that the distortion or flexure breakage happens firstly,then followed by ice rafting.The comprehensively analysed results show that the ice is easily rafted on the simultaneity action of wave,current and wind,and the action of wave can＇t be ignored.Moreover,the rafted ice length increases with the enhancive force of ocean current and wind.
基金supported by the Guangdong Province Research Project(No.2011A091000007)the National Natural Science Foundation of China for its financial support(No.21174162)
文摘Organic/inorganic hybrid polymers have been widely studied for their potential use in nanocontainers and nanocarriers. In this article, one star-shaped hybrid polymer, polyhedral oligomeric silsesquioxane （POSS） grafted poly（N,N-（dimethylamino）ethyl methacrylate） （POSS-g-PDMA）, was synthesized via reversible addition-fragmentation chain transfer polymerization （RAFT）. The pH stimuli-responsive character of POSS-g-PDMA in aqueous solution were also studied.
基金supported by the National Natural Science Foundation of China (Grant Nos. 52205139, 12172021, and 52105156)the National Science and Technology Major Project of China (Grant No. 2019-IV-00170085)+1 种基金the Science Center for Gas Turbine Project (Grant No. P2022-III003-002)the Academic Excellence Foundation of BUAA for PhD Students。
文摘Microstructural rafting of Ni-based single-crystal(SC) superalloys is inevitable at elevated temperatures during long-term service with mechanical loading, which significantly affects the mechanical behaviour of the material. In this study, the effects of rafting on the mesodeformation and fracture behaviour of a Ni-based SC superalloy under cyclic and tensile loads were investigated using in situ scanning electron microscopy(SEM), digital image correlation(DIC), and crystal plasticity finite element method(CP-FEM) simulations. The results indicated that the tensile strength decreased significantly in the rafted specimens. In the cyclic tests, both the virgin and rafted specimens showed an increase in the maximum shear strain with cycle number. The interaction of cross-slip bands was captured by in situ SEM-DIC around the micro-notch of the virgin specimens during the tensile test, while a more homogeneous local deformation field was observed in the rafting specimens. In addition,the fracture behaviour was strongly influenced by the rafting morphology. The crack exhibited instantaneous and long-range fracture features along the octahedral plane as it propagated in the rafting specimen, whereas it deflected over a short distance between the crystallographic planes at an early stage in the virgin specimen, which is consistent with the CP-FEM results.Furthermore, the CP-FEM results for the crack initiation direction on(111) dominant slip plane were consistent with the in situ SEM observations.
基金financed by the National Natural Science Foundation of China(Nos.12402071,92160204)the China Postdoctoral Science Foundation(No.2024M751635)+1 种基金the Postdoctoral Fellowship Program of CPSF,China(No.GZB20240365)the National Science and Technology Major Projects of China(No.J2019-IV-0011-0079).
文摘Thermomechanical Fatigue (TMF) is one of the most dangerous failure modes of high-temperature structures. The effect of coarsened and rafted microstructures on the TMF behavior of Nickel-Base Single Crystal Superalloys (NBSX) was experimentally studied. TMF tests under In-Phase (IP) and Out-of-Phase (OP) paths revealed significant variations in TMF life reduction. Cyclic deformation behaviors of alloys with different microstructures were compared. The effect of microstructure on TMF damage mechanisms was unveiled from characterizations of fracture surfaces and longitudinal sections by scanning electronic microscope and optical microscope. A transition from mode-I to crystallographic fracture in the coarsened alloy during IP-TMF was observed and discussed. Due to the degraded microstructure, the dispersed distribution of crystal slips was distinguished in the coarsened and rafted alloys. The competitive or synergetic interactions among oxidation-assisted mode-I opening, casting pore-related mode-I creep and crystallographic slipping were discussed. This study underscores the complex interplay among microstructure, deformation behaviors and damage mechanisms, offering valuable insights into alloy performance under TMF conditions.
