In order to further reduce the cost of AB5 type rare earth-based hydrogen storage alloy, a low-Co AB5 type hydrogen storage alloy were by substituting Co with Cu and Fe.The characteristics of these alloys have been in...In order to further reduce the cost of AB5 type rare earth-based hydrogen storage alloy, a low-Co AB5 type hydrogen storage alloy were by substituting Co with Cu and Fe.The characteristics of these alloys have been investigated by means of XRD, PCT, and measurement of electrochemical capacity and cycle life.The test results show that the effect of these two kinds of substituting elements on discharge capacity is Cu ＞ Fe, and the cycle life is on the contrary.Both of them have no distinct influence on activity speed, but activity speed increases with the decrease of Co.By the order way, the high discharge rate characteristics rise with the addition of Cu and decreasing of Co.展开更多
AB_(5)-type toxins are a group of secreted protein toxins that are central virulence factors for bacterial pathogens such as Shigella dysenteriae,Vibrio cholerae,Bordetella pertussis,and certain lineages of pathogenic...AB_(5)-type toxins are a group of secreted protein toxins that are central virulence factors for bacterial pathogens such as Shigella dysenteriae,Vibrio cholerae,Bordetella pertussis,and certain lineages of pathogenic Escherichia coli and Salmonella enterica.AB_(5) toxins are composed of an active(A)subunit that manipulates host cell biology in complex with a pentameric binding/delivery(B)subunit that mediates the toxin’s entry into host cells and its subsequent intracellular trafficking.Broadly speaking,all known AB_(5)-type toxins adopt similar structural architectures and employ similar mechanisms of binding,entering and trafficking within host cells.Despite this,there is a remarkable amount of diversity amongst AB_(5)-type toxins;this includes different toxin families with unrelated activities,as well as variation within families that can have profound functional consequences.In this review,we discuss the diversity that exists amongst characterized AB_(5)-type toxins,with an emphasis on the genetic and functional variability within AB_(5) toxin families,how this may have evolved,and its impact on human disease.展开更多
The Li-Mg-N-H(Mg(NH_(2))_(2)-2LiH)system,as a high-capacity Mg-based metal hydrogen storage material(5.6 wt%),has broad prospects for in vehicle hydrogen storage applications,but it still has high hydrogen ab/desorpti...The Li-Mg-N-H(Mg(NH_(2))_(2)-2LiH)system,as a high-capacity Mg-based metal hydrogen storage material(5.6 wt%),has broad prospects for in vehicle hydrogen storage applications,but it still has high hydrogen ab/desorption barriers.To improve its hydrogen storage performance,a nanohydrogen storage alloy was innovatively combined with Mg(NH_(2))_(2)-2LiH,AB5 type nanohydrogen storage alloy LaNi_(5)was prepared by co-precipitation method.Nano LaNi_(5)and single-walled carbon nanotubes(SWCNTs)were co-doped into the Mg(NH_(2))_(2)-2LiH system at a ratio of 10 wt%and 2 wt%,significantly enhancing the hydrogen storage performance of Mg(NH_(2))_(2)-2LiH.The initial hydrogen ab/desorption temperatures of the co-doped system decreased from110/130℃to 45/85℃.The release of by-product ammonia is significantly inhibited.4.73 wt% H_(2)can be ab/desorption in 150 min at 180/170℃.Cycle tests show that the co-doped system can still maintain a hydrogen storage capacity of 4.75 wt% after ten hydrogen release cycles.Mechanism and density functional theory study have shown that during the hydrogen release process,partially hydrogenated LaNi_(5)weakens the chemical bonding in Mg(NH_(2))_(2),promoted the dissociation of hydrogen from the Mg(NH_(2))_(2)-2LiH system,while playing a dual role of"hydrogen overflow"and"hydrogen pump".SWCNTs act as auxiliary agents,helping to refine particle size and increase thermal conductivity.The synergistic effect of the two optimizes the comprehensive hydrogen storage performance of Mg(NH_(2))_(2)-2LiH.This study provides a new research method for improving the comprehensive hydrogen storage performance of Mg-based metal hydrogen storage materials using rare earth element catalysts.展开更多
文摘In order to further reduce the cost of AB5 type rare earth-based hydrogen storage alloy, a low-Co AB5 type hydrogen storage alloy were by substituting Co with Cu and Fe.The characteristics of these alloys have been investigated by means of XRD, PCT, and measurement of electrochemical capacity and cycle life.The test results show that the effect of these two kinds of substituting elements on discharge capacity is Cu ＞ Fe, and the cycle life is on the contrary.Both of them have no distinct influence on activity speed, but activity speed increases with the decrease of Co.By the order way, the high discharge rate characteristics rise with the addition of Cu and decreasing of Co.
基金supported by a start-up grant provided by the Uni-versity of Alberta Faculty of Science(to C.C.F.)a Natural Sciences and Engineering Research Council of Canada(NSERC)Discovery Grant(Grant number:RGPIN-2020-03964 to C.C.F.).
文摘AB_(5)-type toxins are a group of secreted protein toxins that are central virulence factors for bacterial pathogens such as Shigella dysenteriae,Vibrio cholerae,Bordetella pertussis,and certain lineages of pathogenic Escherichia coli and Salmonella enterica.AB_(5) toxins are composed of an active(A)subunit that manipulates host cell biology in complex with a pentameric binding/delivery(B)subunit that mediates the toxin’s entry into host cells and its subsequent intracellular trafficking.Broadly speaking,all known AB_(5)-type toxins adopt similar structural architectures and employ similar mechanisms of binding,entering and trafficking within host cells.Despite this,there is a remarkable amount of diversity amongst AB_(5)-type toxins;this includes different toxin families with unrelated activities,as well as variation within families that can have profound functional consequences.In this review,we discuss the diversity that exists amongst characterized AB_(5)-type toxins,with an emphasis on the genetic and functional variability within AB_(5) toxin families,how this may have evolved,and its impact on human disease.
基金financially supported by the National Natural Science Foundation of China(Nos.51971199 and 51771171)
文摘The Li-Mg-N-H(Mg(NH_(2))_(2)-2LiH)system,as a high-capacity Mg-based metal hydrogen storage material(5.6 wt%),has broad prospects for in vehicle hydrogen storage applications,but it still has high hydrogen ab/desorption barriers.To improve its hydrogen storage performance,a nanohydrogen storage alloy was innovatively combined with Mg(NH_(2))_(2)-2LiH,AB5 type nanohydrogen storage alloy LaNi_(5)was prepared by co-precipitation method.Nano LaNi_(5)and single-walled carbon nanotubes(SWCNTs)were co-doped into the Mg(NH_(2))_(2)-2LiH system at a ratio of 10 wt%and 2 wt%,significantly enhancing the hydrogen storage performance of Mg(NH_(2))_(2)-2LiH.The initial hydrogen ab/desorption temperatures of the co-doped system decreased from110/130℃to 45/85℃.The release of by-product ammonia is significantly inhibited.4.73 wt% H_(2)can be ab/desorption in 150 min at 180/170℃.Cycle tests show that the co-doped system can still maintain a hydrogen storage capacity of 4.75 wt% after ten hydrogen release cycles.Mechanism and density functional theory study have shown that during the hydrogen release process,partially hydrogenated LaNi_(5)weakens the chemical bonding in Mg(NH_(2))_(2),promoted the dissociation of hydrogen from the Mg(NH_(2))_(2)-2LiH system,while playing a dual role of"hydrogen overflow"and"hydrogen pump".SWCNTs act as auxiliary agents,helping to refine particle size and increase thermal conductivity.The synergistic effect of the two optimizes the comprehensive hydrogen storage performance of Mg(NH_(2))_(2)-2LiH.This study provides a new research method for improving the comprehensive hydrogen storage performance of Mg-based metal hydrogen storage materials using rare earth element catalysts.
