As one of important members of refractory materials,tungsten phosphide(WP)holds great potential for fundamental study and industrial applications in many fields of science and technology,due to its excellent propertie...As one of important members of refractory materials,tungsten phosphide(WP)holds great potential for fundamental study and industrial applications in many fields of science and technology,due to its excellent properties such as superconductivity and as-predicted topological band structure.However,synthesis of high-quality WP crystals is still a challenge by using tradition synthetic methods,because the synthesis temperature for growing its large crystals is very stringently required to be as high as 3000℃,which is far beyond the temperature capability of most laboratory-based devices for crystal growth.In addition,high temperature often induces the decomposition of metal phosphides,leading to off-stoichiometric samples based on which the materials'intrinsic properties cannot be explored.In this work,we report a high-pressure synthesis of single-crystal WP through a direct crystallization from cooling the congruent W-P melts at 5 GPa and^3200℃.In combination of x-ray diffraction,electron microscope,and thermal analysis,the crystal structure,morphology,and stability of recovered sample are well investigated.The final product is phase-pure and nearly stoichiometric WP in a single-crystal form with a large grain size,in excess of one millimeter,thus making it feasible to implement most experimental measurements,especially,for the case where a large crystal is required.Success in synthesis of high-quality WP crystals at high pressure can offer great opportunities for determining their intrinsic properties and also making more efforts to study the family of transition-metal phosphides.展开更多
Anti-perovskite solid-state electrolyte Li_(2)OHCl usually exhibits orthorhombic phase and low ionic conductivity at room temperature.However,its ionic conductivity increases greatly when the temperature is up to 40℃...Anti-perovskite solid-state electrolyte Li_(2)OHCl usually exhibits orthorhombic phase and low ionic conductivity at room temperature.However,its ionic conductivity increases greatly when the temperature is up to 40℃,while it goes through an orthorhombic-to-cubic phase transition.The cubic Li_(2)OHCl with high ionic conductivity is stabilized at room temperature and even lower temperature about 10℃ by a simple synthesis method of wet mechanical milling.The cubic Li_(2)OHCl prepared by this method performs an ionic conductivity of 4.27×10^(-6) S/cm at room temperature,about one order of magnitude higher than that of the orthorhombic Li_(2)OHCl.The phase-transition temperature is decreased to around 10℃.Moreover,it can still remain cubic phase after heat treatment at 210℃.This work delivers a huge potential of fabricating high ionic conductivity phase antiperovskite solid-state electrolyte materials by wet mechanical milling.展开更多
Methane clathrate hydrate(MCH)is a promising energy resource,but controllable extraction of CH4 from MCH remains a challenge.Gradually replacing CH4 in MCH with CO2 is an attractive scheme,as it is cost efficient and ...Methane clathrate hydrate(MCH)is a promising energy resource,but controllable extraction of CH4 from MCH remains a challenge.Gradually replacing CH4 in MCH with CO2 is an attractive scheme,as it is cost efficient and mitigates the environmentally harmful effects of CO2 by sequestration.However,the practicable implementation of this method has not yet been achieved.In this study,using in situ neutron diffraction,we confirm that CH4 in the 51262 cages of bulk structure-I(si)MCH can be substituted by gaseous CO2 under high pressure and low temperature with a high substitution ratio(~44%)while conserving the structure of the hydrate framework.First-principles calculations indicate that CO2 binds more strongly to the 51262 cages than methane does,and that the diffusion barrier for CH4 is significantly lowered by an intermediate state in which one hydrate cage is doubly occupied by CH4 and CO2.Therefore,exchange of CO2 for CH4 in MCH is not only energetically favorable but also kinetically feasible.Experimental and theoretical studies of CH4/CO2 substitution elucidate a method to harness energy from these combustible ice resources.展开更多
Objective To observe the surface structures of cardiovascular endothelial cells in situ with atomic force microscope (AFM). Methods Fresh aorta and aortic valve were dissected from 10 healthy male New Zealand white ...Objective To observe the surface structures of cardiovascular endothelial cells in situ with atomic force microscope (AFM). Methods Fresh aorta and aortic valve were dissected from 10 healthy male New Zealand white rabbits. Before fixed in 1% formaldehyde, the fresh tissues were washed in the buffer phosphate solution. Under general microscope, the fixed aorta or valve was spread on the double side stick tape which had already been stuck on the glass slide. The intima of aorta or the aorta side of valve was towards upside, Then the specimen was dried under 37 degrees centigrade in an attemperator and was washed with pure water. After dried again, the specimen was loaded on the platform ofNanoScope Ⅲa AFM and was scanned in tapping mode with the scanning speed of 0.5 HZ. Results The surface structures of endothelial cell on the fixed and dried tissue could be observed clearly in situ with AFM. aortic endothelial cells were large, branched and arranged sparsely and parallel to the direction of blood flow, whereas endothelial cells on aorta valve surface were small, less branched and arranged intensively and vertical to the direction of blood flow. When the scanning range was dwindled, granular ultra-structures could be observed on the surface of endothelial cells, and, as the scanning range was dwindled further, fissure and convolution could be seen on the surface of granules from aortic endothelial cells. Centre cavity and surrounding swelling volcano-like structure could be seen on the surface of granules from endothelial cells of aortic valve. Conclusions It's feasible to observe the surface ultra-structures of cardiovascular endothelial cells in situ with AFM and morphological information provided by AFM might be of clinical value in future histopathological diagnosis(JGeriatr Cardiol2009; 6:178-181).展开更多
基金the National Key Research and Development Program of China(Grant Nos.2016YFA0401503 and 2018YFA0305700)the National Natural Science Foundation of China(Grant No.11575288)+4 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2016006)the Key Research Platforms and Research Projects of Universities in Guangdong Province,China(Grant No.2018KZDXM062)the Guangdong Innovative&Entrepreneurial Research Team Program,China(Grant No.2016ZT06C279)the Shenzhen Peacock Plan,China(Grant No.KQTD2016053019134356)the Shenzhen Development&Reform Commission Foundation for Novel Nano-Material Sciences,China,the Research Platform for Crystal Growth&Thin-Film Preparation at SUST,China,and the Shenzhen Development and Reform Commission Foundation for Shenzhen Engineering Research Center for Frontier Materials Synthesis at High Pressure,China.
文摘As one of important members of refractory materials,tungsten phosphide(WP)holds great potential for fundamental study and industrial applications in many fields of science and technology,due to its excellent properties such as superconductivity and as-predicted topological band structure.However,synthesis of high-quality WP crystals is still a challenge by using tradition synthetic methods,because the synthesis temperature for growing its large crystals is very stringently required to be as high as 3000℃,which is far beyond the temperature capability of most laboratory-based devices for crystal growth.In addition,high temperature often induces the decomposition of metal phosphides,leading to off-stoichiometric samples based on which the materials'intrinsic properties cannot be explored.In this work,we report a high-pressure synthesis of single-crystal WP through a direct crystallization from cooling the congruent W-P melts at 5 GPa and^3200℃.In combination of x-ray diffraction,electron microscope,and thermal analysis,the crystal structure,morphology,and stability of recovered sample are well investigated.The final product is phase-pure and nearly stoichiometric WP in a single-crystal form with a large grain size,in excess of one millimeter,thus making it feasible to implement most experimental measurements,especially,for the case where a large crystal is required.Success in synthesis of high-quality WP crystals at high pressure can offer great opportunities for determining their intrinsic properties and also making more efforts to study the family of transition-metal phosphides.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(Grant No.2021A1515011784)the Key Program of the National Natural Science Foundation of China(Grant No.51732005)+2 种基金the Shenzhen Science and Technology Program(Grant No.KQTD20200820113047086)21C Innovation Laboratory,Contemporary Amperex Technology Ltd(Grant No.C-ND-21C LAB-210044-1.0)the Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology。
文摘Anti-perovskite solid-state electrolyte Li_(2)OHCl usually exhibits orthorhombic phase and low ionic conductivity at room temperature.However,its ionic conductivity increases greatly when the temperature is up to 40℃,while it goes through an orthorhombic-to-cubic phase transition.The cubic Li_(2)OHCl with high ionic conductivity is stabilized at room temperature and even lower temperature about 10℃ by a simple synthesis method of wet mechanical milling.The cubic Li_(2)OHCl prepared by this method performs an ionic conductivity of 4.27×10^(-6) S/cm at room temperature,about one order of magnitude higher than that of the orthorhombic Li_(2)OHCl.The phase-transition temperature is decreased to around 10℃.Moreover,it can still remain cubic phase after heat treatment at 210℃.This work delivers a huge potential of fabricating high ionic conductivity phase antiperovskite solid-state electrolyte materials by wet mechanical milling.
基金Supported by the National Key R&D Program of China under Grant Nos 2016YFA0401503 and 2018YFA0305700the National Natural Science Foundation of China under Grant Nos 11575288,11775011,21703006,21773005+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2016006.J.Zhu was supported by the National Thousand-Young-Talents Program and the National Science Associated Funding Grant U1530402The experimental work has benefited from the use of the neutron source at Los Alamos Neutron Science Center(LANSCE),which is funded by the U.S.Department of Energy’s Office of Basic Energy Sciences.
文摘Methane clathrate hydrate(MCH)is a promising energy resource,but controllable extraction of CH4 from MCH remains a challenge.Gradually replacing CH4 in MCH with CO2 is an attractive scheme,as it is cost efficient and mitigates the environmentally harmful effects of CO2 by sequestration.However,the practicable implementation of this method has not yet been achieved.In this study,using in situ neutron diffraction,we confirm that CH4 in the 51262 cages of bulk structure-I(si)MCH can be substituted by gaseous CO2 under high pressure and low temperature with a high substitution ratio(~44%)while conserving the structure of the hydrate framework.First-principles calculations indicate that CO2 binds more strongly to the 51262 cages than methane does,and that the diffusion barrier for CH4 is significantly lowered by an intermediate state in which one hydrate cage is doubly occupied by CH4 and CO2.Therefore,exchange of CO2 for CH4 in MCH is not only energetically favorable but also kinetically feasible.Experimental and theoretical studies of CH4/CO2 substitution elucidate a method to harness energy from these combustible ice resources.
文摘Objective To observe the surface structures of cardiovascular endothelial cells in situ with atomic force microscope (AFM). Methods Fresh aorta and aortic valve were dissected from 10 healthy male New Zealand white rabbits. Before fixed in 1% formaldehyde, the fresh tissues were washed in the buffer phosphate solution. Under general microscope, the fixed aorta or valve was spread on the double side stick tape which had already been stuck on the glass slide. The intima of aorta or the aorta side of valve was towards upside, Then the specimen was dried under 37 degrees centigrade in an attemperator and was washed with pure water. After dried again, the specimen was loaded on the platform ofNanoScope Ⅲa AFM and was scanned in tapping mode with the scanning speed of 0.5 HZ. Results The surface structures of endothelial cell on the fixed and dried tissue could be observed clearly in situ with AFM. aortic endothelial cells were large, branched and arranged sparsely and parallel to the direction of blood flow, whereas endothelial cells on aorta valve surface were small, less branched and arranged intensively and vertical to the direction of blood flow. When the scanning range was dwindled, granular ultra-structures could be observed on the surface of endothelial cells, and, as the scanning range was dwindled further, fissure and convolution could be seen on the surface of granules from aortic endothelial cells. Centre cavity and surrounding swelling volcano-like structure could be seen on the surface of granules from endothelial cells of aortic valve. Conclusions It's feasible to observe the surface ultra-structures of cardiovascular endothelial cells in situ with AFM and morphological information provided by AFM might be of clinical value in future histopathological diagnosis(JGeriatr Cardiol2009; 6:178-181).