Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero...Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero-dimensional(OD) fullerenes and nanoparticles,one-dimensional(1D) nanotubes and nanoribbons,two-dimensional(2D) nanosheets as well as three-dimensional(3D) nanoporous BN.Combining low-dimensional quantum confinement and surface effects with unique physical and chemical properties of BN,e.g.excellent electric insulation,wide band gap,and high chemical and thermal stability,BN nanomaterials have drawn particular attention in a variety of potential applications,e.g.luminescence,functional composites,hydrogen accumulators,and advanced insulators,which are also reviewed.展开更多
A hierarchical model is developed to predict the streaming potential （SP） in the canaliculi of a loaded os teon. Canaliculi are assumed to run straight across the os teon annular cylinder wall, while disregarding th...A hierarchical model is developed to predict the streaming potential （SP） in the canaliculi of a loaded os teon. Canaliculi are assumed to run straight across the os teon annular cylinder wall, while disregarding the effect of lacuna. SP is generalized by the canalicular fluid flow. Ana lytical solutions are obtained for the canalicular fluid veloc ity, pressure, and SP. Results demonstrate that SP amplitude （SPA） is proportional to the pressure difference, strain am plitude, frequency, and strain rate amplitude. However, the key loading factor governing SP is the strain rate, which is a representative loading parameter under the specific phys iological state. Moreover, SPA is independent of canalicu lar length. This model links external loads to the canalicu lar fluid pressure, velocity, and SP, which can facilitate fur ther understanding of the mechanotransduction and electro mechanotransduction mechanisms of bones.展开更多
The Canadian Nuclear Safety Commission(CNSC), Canada’s nuclear regulator, conducts regulatory research in order to develop independent knowledge on safety aspects related to the deep geological disposal of radioactiv...The Canadian Nuclear Safety Commission(CNSC), Canada’s nuclear regulator, conducts regulatory research in order to develop independent knowledge on safety aspects related to the deep geological disposal of radioactive wastes. In Canada, the Cobourg limestone of the Michigan Basin is currently considered as a potential host formation for geological disposal. The understanding of the hydromechanical behavior of such a host rock is one of the essential requirements for the assessment of its performance as a barrier against radionuclide migration. The excavation of galleries and shafts of a deep geological repository(DGR) can induce damage to the surrounding rock. The excavation damaged zone(EDZ) has higher permeability and reduced strength compared to the undisturbed rock and those factors must be considered in the design and safety assessment of the DGR. The extent and characteristics of the EDZ depend on the size of the opening, the rock type and its properties, and the in situ stresses, among other factors. In addition, the extent and characteristics of the EDZ can change with time due to rock strength degradation, evolution of fractures within the EDZ, and the redistribution of pore pressure around the excavation. In this research project initiated by the CNSC, the authors conducted experimental and theoretical research in order to assess the hydro-mechanical behavior of the Cobourg limestone under undamaged and damaged conditions, both in the short and long terms. The short-term behavior was investigated by a program of triaxial tests with the measurement of permeability evolution on specimens of Cobourg limestone. The authors formulate a coupled hydro-mechanical model to simulate the stress-strain response and evolution of the permeability during those triaxial tests. Using creep and relaxation data from a similar limestone, the model was extended to include its long-term strength degradation. The model successfully simulated both the short-and long-term hydro-mechanical behavior of the limestone during those tests. This provides confidence that the main physical processes have been adequately understood and formulated.展开更多
Three cement samples were prepared, includi ng OPC consisted of 100wt% portland cement, PFA consisted of 70wt% portland cemen t and 30wt% fly-ash, and CA consisted of 70wt% portland cement and 30wt% modifi ed fly ash...Three cement samples were prepared, includi ng OPC consisted of 100wt% portland cement, PFA consisted of 70wt% portland cemen t and 30wt% fly-ash, and CA consisted of 70wt% portland cement and 30wt% modifi ed fly ash. The strength of hardened cement paste of these samples was tested an d their pore structures were determined by a mercury intrusion porosimeter. More over,the data of the pore structures of three samples were comprehensively analy zed. The relations between the pore structures and the compressive strength of t he three samples were studied. The experimental results show that the relations between the porosity determined by the mercury intrusion porosimeter and the com pressive strength are not notable, and the total pore surface area, the average pore diameter and the median pore diameter could be used to explain the differen ce of the strength of the tested samples.展开更多
基金financial support of International Center for Young Scientists(ICYS)World Premier International Center for Materials Nanoarchitectonics(WPI-MANA) in National Institute for Materials Science(NIMS)financial support from KAKENHI project(Grant-in-Aid for Young Scientists,26820322) of Japan Society for the Promotion of Science(JSPS)
文摘Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero-dimensional(OD) fullerenes and nanoparticles,one-dimensional(1D) nanotubes and nanoribbons,two-dimensional(2D) nanosheets as well as three-dimensional(3D) nanoporous BN.Combining low-dimensional quantum confinement and surface effects with unique physical and chemical properties of BN,e.g.excellent electric insulation,wide band gap,and high chemical and thermal stability,BN nanomaterials have drawn particular attention in a variety of potential applications,e.g.luminescence,functional composites,hydrogen accumulators,and advanced insulators,which are also reviewed.
基金supported by the OIT of Higher Learning Institutions of Shanxithe National Natural Science Foundation of China(11302143,11472185)Natural Science Fund of Shanxi(2014021013)
文摘A hierarchical model is developed to predict the streaming potential （SP） in the canaliculi of a loaded os teon. Canaliculi are assumed to run straight across the os teon annular cylinder wall, while disregarding the effect of lacuna. SP is generalized by the canalicular fluid flow. Ana lytical solutions are obtained for the canalicular fluid veloc ity, pressure, and SP. Results demonstrate that SP amplitude （SPA） is proportional to the pressure difference, strain am plitude, frequency, and strain rate amplitude. However, the key loading factor governing SP is the strain rate, which is a representative loading parameter under the specific phys iological state. Moreover, SPA is independent of canalicu lar length. This model links external loads to the canalicu lar fluid pressure, velocity, and SP, which can facilitate fur ther understanding of the mechanotransduction and electro mechanotransduction mechanisms of bones.
基金the Canadian Nuclear Safety Commission for funding this project
文摘The Canadian Nuclear Safety Commission(CNSC), Canada’s nuclear regulator, conducts regulatory research in order to develop independent knowledge on safety aspects related to the deep geological disposal of radioactive wastes. In Canada, the Cobourg limestone of the Michigan Basin is currently considered as a potential host formation for geological disposal. The understanding of the hydromechanical behavior of such a host rock is one of the essential requirements for the assessment of its performance as a barrier against radionuclide migration. The excavation of galleries and shafts of a deep geological repository(DGR) can induce damage to the surrounding rock. The excavation damaged zone(EDZ) has higher permeability and reduced strength compared to the undisturbed rock and those factors must be considered in the design and safety assessment of the DGR. The extent and characteristics of the EDZ depend on the size of the opening, the rock type and its properties, and the in situ stresses, among other factors. In addition, the extent and characteristics of the EDZ can change with time due to rock strength degradation, evolution of fractures within the EDZ, and the redistribution of pore pressure around the excavation. In this research project initiated by the CNSC, the authors conducted experimental and theoretical research in order to assess the hydro-mechanical behavior of the Cobourg limestone under undamaged and damaged conditions, both in the short and long terms. The short-term behavior was investigated by a program of triaxial tests with the measurement of permeability evolution on specimens of Cobourg limestone. The authors formulate a coupled hydro-mechanical model to simulate the stress-strain response and evolution of the permeability during those triaxial tests. Using creep and relaxation data from a similar limestone, the model was extended to include its long-term strength degradation. The model successfully simulated both the short-and long-term hydro-mechanical behavior of the limestone during those tests. This provides confidence that the main physical processes have been adequately understood and formulated.
基金Funded by the National Key Fundamental Research and Develop ment Program of China(2001CB610703)
文摘Three cement samples were prepared, includi ng OPC consisted of 100wt% portland cement, PFA consisted of 70wt% portland cemen t and 30wt% fly-ash, and CA consisted of 70wt% portland cement and 30wt% modifi ed fly ash. The strength of hardened cement paste of these samples was tested an d their pore structures were determined by a mercury intrusion porosimeter. More over,the data of the pore structures of three samples were comprehensively analy zed. The relations between the pore structures and the compressive strength of t he three samples were studied. The experimental results show that the relations between the porosity determined by the mercury intrusion porosimeter and the com pressive strength are not notable, and the total pore surface area, the average pore diameter and the median pore diameter could be used to explain the differen ce of the strength of the tested samples.
