Chemical effects on the Kβ/Kα intensity ratios and △E energy differences for Co, Ni, Cu, and Zn complexes were investigated. The samples were excited by 59.5 keV γ-rays from a ^241Am annular radioactive source. K ...Chemical effects on the Kβ/Kα intensity ratios and △E energy differences for Co, Ni, Cu, and Zn complexes were investigated. The samples were excited by 59.5 keV γ-rays from a ^241Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. We observed the effects of different ligands on the Kβ/Kα intensity ratios and △E energy differences for Co, Ni, Cu, and Zn complexes. We tried to investigate chemical effects on central atoms using the behaviors of different ligands in these complexes. The experimental values of Kβ/Kα were compared with the theoretical and other experimental values of pure Co, Ni, Cu, and Zn.展开更多
Architected stretchable materials with well-organized microarchitectures evolve very rapidly due to their potential in customizing mechanical properties and achieving exotic functions.In many applications,the architec...Architected stretchable materials with well-organized microarchitectures evolve very rapidly due to their potential in customizing mechanical properties and achieving exotic functions.In many applications,the architected stretchable materials are required to sustain large deformation,and their fracture is size-dependent.However,the size effect on the fracture of architected stretchable materials is still elusive.Here,we study this issue by experiment and finite element calculation.It is found that the fracture energy of architected stretchable materials increases with the specimen size ratio,H/h,within a range.When H/h reaches a transition ratio,Rt,the fracture energy approaches a plateau.This transition ratio differentiates the size-dependent and size-independent fracture behavior of architected stretchable materials.The mechanical properties of constituent material only have a minor effect on the transition ratio.The degree of constraint and stress concentration at the node,which are affected by the geometry of the unit-cell,dominate the specimen size effect.The result gives a practical guidance in choosing the specimen size to measure the steady state fracture energy of this class of materials.This work provides insights into the fracture of architected stretchable materials and design for fractureresistant architected stretchable devices.展开更多
A honeycomb structure with a negative Poisson’s ratio(NPR)was designed,fabricated,and analyzed for utilization in personal protective clothing(PPC).The mechanical properties were investigated using a quasi-static mec...A honeycomb structure with a negative Poisson’s ratio(NPR)was designed,fabricated,and analyzed for utilization in personal protective clothing(PPC).The mechanical properties were investigated using a quasi-static mechanical testing and the Hopkinson pressure bar experimental system,and results were compared with similar samples containing regular hexagonal and regular quadrilateral honeycomb structures.The experimental results showed that under quasi-static loadings,the concave honeycomb structure had the highest compressive modulus and yield strength,which produced the highest strain absorption energy,anti-deformation performance and energy absorption.When exposed to a dynamic load at a high strain rate,the concave honeycomb also exhibited the highest dynamic compression modulus,the best impact resistance and best energy absorption among the three structures.In summary,the concave honeycomb structure was more resistant to deformation and had higher impact resistance than the regular hexagonal and regular quadrilateral honeycombs,and exhibited better energy absorption,which makes it a good candidate for application as a personal safety protection material.展开更多
【目的】为解决传统蒸馏装置蒸馏液体时的高能耗和低能效比问题,提出一种采用循环水作为冷却介质的耦合热电制冷器(thermo electric cooler,TEC)的蒸馏装置。【方法】首先选取甲醇作为目标液体进行试验验证;然后考察TEC冷热端的热力学...【目的】为解决传统蒸馏装置蒸馏液体时的高能耗和低能效比问题,提出一种采用循环水作为冷却介质的耦合热电制冷器(thermo electric cooler,TEC)的蒸馏装置。【方法】首先选取甲醇作为目标液体进行试验验证;然后考察TEC冷热端的热力学参数在不同输入电压下对系统蒸馏速率及能效比的影响。【结果】使用4片型号为TEC1-12706的制冷片,当循环水流速为40 L/h、电压为15 V时,甲醇的馏出速率最大值为18.7 g/min,此时系统的能效比最高为285.5%。【结论】本研究结果可为传统蒸馏装置能效比的提升提供一些参考。展开更多
文摘Chemical effects on the Kβ/Kα intensity ratios and △E energy differences for Co, Ni, Cu, and Zn complexes were investigated. The samples were excited by 59.5 keV γ-rays from a ^241Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. We observed the effects of different ligands on the Kβ/Kα intensity ratios and △E energy differences for Co, Ni, Cu, and Zn complexes. We tried to investigate chemical effects on central atoms using the behaviors of different ligands in these complexes. The experimental values of Kβ/Kα were compared with the theoretical and other experimental values of pure Co, Ni, Cu, and Zn.
基金supported by the National Natural Science Foundation of China[12002255]National Key R&D Program of China[2021YFB3201700].
文摘Architected stretchable materials with well-organized microarchitectures evolve very rapidly due to their potential in customizing mechanical properties and achieving exotic functions.In many applications,the architected stretchable materials are required to sustain large deformation,and their fracture is size-dependent.However,the size effect on the fracture of architected stretchable materials is still elusive.Here,we study this issue by experiment and finite element calculation.It is found that the fracture energy of architected stretchable materials increases with the specimen size ratio,H/h,within a range.When H/h reaches a transition ratio,Rt,the fracture energy approaches a plateau.This transition ratio differentiates the size-dependent and size-independent fracture behavior of architected stretchable materials.The mechanical properties of constituent material only have a minor effect on the transition ratio.The degree of constraint and stress concentration at the node,which are affected by the geometry of the unit-cell,dominate the specimen size effect.The result gives a practical guidance in choosing the specimen size to measure the steady state fracture energy of this class of materials.This work provides insights into the fracture of architected stretchable materials and design for fractureresistant architected stretchable devices.
基金Supported by the National Natural Science Foundation of China(51606011)。
文摘A honeycomb structure with a negative Poisson’s ratio(NPR)was designed,fabricated,and analyzed for utilization in personal protective clothing(PPC).The mechanical properties were investigated using a quasi-static mechanical testing and the Hopkinson pressure bar experimental system,and results were compared with similar samples containing regular hexagonal and regular quadrilateral honeycomb structures.The experimental results showed that under quasi-static loadings,the concave honeycomb structure had the highest compressive modulus and yield strength,which produced the highest strain absorption energy,anti-deformation performance and energy absorption.When exposed to a dynamic load at a high strain rate,the concave honeycomb also exhibited the highest dynamic compression modulus,the best impact resistance and best energy absorption among the three structures.In summary,the concave honeycomb structure was more resistant to deformation and had higher impact resistance than the regular hexagonal and regular quadrilateral honeycombs,and exhibited better energy absorption,which makes it a good candidate for application as a personal safety protection material.
