Phase change solvents are attractive energy-efficient absorbents for carbon dioxide(CO_2) capture due to CO_2-rich phase formation. Potassium prolinate + water + ethanol(ProK/W/Eth) solution has shown good capture cha...Phase change solvents are attractive energy-efficient absorbents for carbon dioxide(CO_2) capture due to CO_2-rich phase formation. Potassium prolinate + water + ethanol(ProK/W/Eth) solution has shown good capture characteristics as a promising one in our previous work. In this work, absorption rate of CO_2, solubility of N2 O,and heat of absorption for ProK/W/Eth solution were investigated using a stirred cell reactor and a CPA201 reaction calorimeter and these results were also compared with the aqueous ProK and 30 mass% MEA solutions.Using ethanol as a solvent can substantially increase the CO_2 physical solubility and the absorption rate of CO_2 in ProK/W/Eth solutions is far higher than that in aqueous 30 mass% MEA solutions especially at a low CO_2 loading range. Solid precipitation, obtained from the liquid-to-solid phase change absorption, was analyzed by13 C NMR and DSC-TGA. The enthalpy change for ProK/W/Eth solutions at various CO_2 loading was also discussed.展开更多
Phase engineering is an important strategy to modulate the electronic structure of molybdenum disulfide(MoS_(2)).MoS_(2)-based composites are usually used for the electromagnetic wave(EMW)absorber,but the effect of di...Phase engineering is an important strategy to modulate the electronic structure of molybdenum disulfide(MoS_(2)).MoS_(2)-based composites are usually used for the electromagnetic wave(EMW)absorber,but the effect of different phases on the EMW absorbing performance,such as 1T and 2H phase,is still not studied.In this work,micro-1T/2H MoS_(2) is achieved via a facile one-step hydrother-mal route,in which the 1T phase is induced by the intercalation of guest molecules and ions.The EMW absorption mechanism of single MoS_(2) is revealed by presenting a comparative study between 1T/2H MoS_(2) and 2H MoS_(2).As a result,1T/2H MoS_(2) with the matrix loading of 15%exhibits excellent microwave absorption property than 2H MoS_(2).Furthermore,taking the advantage of 1T/2H MoS_(2),a flexible EMW absorbers that ultrathin 1T/2H MoS_(2)grown on the carbon fiber also performs outstanding performance only with the matrix loading of 5%.This work offers necessary reference to improve microwave absorption performance by phase engineering and design a new type of flexible electromagnetic wave absorption material to apply for the portable microwave absorption electronic devices.展开更多
The human foot is a very complex structure comprising numerous bones, muscles, ligaments and synovial joints. As the only component in contact with the ground, the foot complex delivers a variety of biomechanical func...The human foot is a very complex structure comprising numerous bones, muscles, ligaments and synovial joints. As the only component in contact with the ground, the foot complex delivers a variety of biomechanical functions during human locomotion, e.g. body support and propulsion, stability maintenance and impact absorption. These need the human foot to be rigid and damped to transmit ground reaction forces to the upper body and maintain body stability, and also to be compliant and resilient to moderate risky impacts and save energy. How does the human foot achieve these apparent conflicting functions？ In this study, we propose a phase-dependent hypothesis for the overall locomotor functions of the human foot complex based on in-vivo measurements of human natural gait and simulation results of a mathematical foot model. We propse that foot functions are highly dependent on gait phase, which is a major characteristics of human locomotion. In early stance just after heel strike, the foot mainly works as a shock absorber by moderating high impacts using the viscouselastic heel pad in both vertical and horizontal directions. In mid-stance phase （-80% of stance phase）, the foot complex can be considered as a springy rocker, reserving external mechanical work using the foot arch whilst moving ground contact point forward along a curved path to maintain body stability. In late stance after heel off, the foot complex mainly serves as a force modulator like a gear box, modulating effective mechanical advantages of ankle plantiflexor muscles using metatarsal-phalangeal joints. A sound under- standing of how diverse functions are implemented in a simple foot segment during human locomotion might be useful to gain insight into the overall foot locomotor functions and hence to facilitate clinical diagnosis, rehabilitation product design and humanoid robot development.展开更多
We investigate a simple evolutionary game model in one dimension. It is found that the system exhibits a discontinuous phase transition from a defection state to a cooperation state when the b payoff of a defector exp...We investigate a simple evolutionary game model in one dimension. It is found that the system exhibits a discontinuous phase transition from a defection state to a cooperation state when the b payoff of a defector exploiting a cooperator is small. Furthermore, if b is large enough, then the system exhibits two continuous phase transitions between two absorbing states and a coexistence state of cooperation and defection, respectively. The tri-critical point is roughly estimated. Moreover, it is found that the critical behavior of the continuous phase transition with an absorbing state is in the directed percolation universality class.展开更多
The electrochemical performance of double phase Mg Ni alloy was characterized at 25°C and 70°C, in order to evaluate briefly its utility as negative electrode materials in nickel metal hydride batteries. ...The electrochemical performance of double phase Mg Ni alloy was characterized at 25°C and 70°C, in order to evaluate briefly its utility as negative electrode materials in nickel metal hydride batteries. The results show that the electrochemical capacity of double phase Mg Ni alloy is rarely low at 25°C, but increased rapidly when the temperature is enhanced, and the double phase Mg Ni alloy has its maximum capacity at the first discharge cycle, but the capacity degrades rapidly with cycling number.展开更多
MXenes,drawn from MAX phases,are special two-dimensional substances with numerous advantages in nonlinear optics,specifically in giant and ultrashort pulsed-laser applications.Ti_(3)C_(2)T_(x)and Ti_(2)CT_(x)nanosheet...MXenes,drawn from MAX phases,are special two-dimensional substances with numerous advantages in nonlinear optics,specifically in giant and ultrashort pulsed-laser applications.Ti_(3)C_(2)T_(x)and Ti_(2)CT_(x)nanosheets however rapidly deteriorate under ambient conditions,limiting their applications.This paper demonstrates how excellent modulation depth of one of the MAX phase compounds vanadium zinc carbide(V_2ZnC)makes it a brilliant saturable absorber(SA)in passively Q-switched all-fiber pulsed lasers,integrated such that a 16.73-μm V_(2)ZnC-polyvinyl alcohol(PVA)thin film acts as SA in the laser.Saturable and non-saturable absorptions were found to be 13.2%and 10.47%,while saturation optical intensity and modulation depth were 6.25 k W/cm^(2)and 12.43%,respectively,illustrating the optical nonlinearity.The superiority of MAX-PVA,fabricated in four distinct ratios,was demonstrated by the fact that it self-starts a giant pulsed laser at pump power as low as 22.5 mW and firmly accomplished 120.6 kHz repetition rate with a pulse width of 2.08μs.It is a fine SA for the use of pulsed-laser production using all-fiber laser due to fabrication simplicity and great optical,thermophysical,and mechanical qualities.展开更多
基金Supported by Hebei Provincial Natural Science Foundation for Distinguished Young Scholars of China(Grant No.B2015208067)Training Program for Talent Engineering of Hebei Province(Grant No.A2017002022)Key Program of Hebei Provincial Natural Science Foundation(Grant No.B2018208154)
文摘Phase change solvents are attractive energy-efficient absorbents for carbon dioxide(CO_2) capture due to CO_2-rich phase formation. Potassium prolinate + water + ethanol(ProK/W/Eth) solution has shown good capture characteristics as a promising one in our previous work. In this work, absorption rate of CO_2, solubility of N2 O,and heat of absorption for ProK/W/Eth solution were investigated using a stirred cell reactor and a CPA201 reaction calorimeter and these results were also compared with the aqueous ProK and 30 mass% MEA solutions.Using ethanol as a solvent can substantially increase the CO_2 physical solubility and the absorption rate of CO_2 in ProK/W/Eth solutions is far higher than that in aqueous 30 mass% MEA solutions especially at a low CO_2 loading range. Solid precipitation, obtained from the liquid-to-solid phase change absorption, was analyzed by13 C NMR and DSC-TGA. The enthalpy change for ProK/W/Eth solutions at various CO_2 loading was also discussed.
基金the National Natural Science Foundation of China(No.51672222)Joint Fund Project-Enterprise-Shaanxi Coal Joint Fund Project(2019JLM-32)+2 种基金Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX202054)the Graduate innovation team of Northwestern Polytechnical Universitythe Analysis and Testing Center of Northwestern Polytechnical University for their technical assistance in SEM(Verios G4).
文摘Phase engineering is an important strategy to modulate the electronic structure of molybdenum disulfide(MoS_(2)).MoS_(2)-based composites are usually used for the electromagnetic wave(EMW)absorber,but the effect of different phases on the EMW absorbing performance,such as 1T and 2H phase,is still not studied.In this work,micro-1T/2H MoS_(2) is achieved via a facile one-step hydrother-mal route,in which the 1T phase is induced by the intercalation of guest molecules and ions.The EMW absorption mechanism of single MoS_(2) is revealed by presenting a comparative study between 1T/2H MoS_(2) and 2H MoS_(2).As a result,1T/2H MoS_(2) with the matrix loading of 15%exhibits excellent microwave absorption property than 2H MoS_(2).Furthermore,taking the advantage of 1T/2H MoS_(2),a flexible EMW absorbers that ultrathin 1T/2H MoS_(2)grown on the carbon fiber also performs outstanding performance only with the matrix loading of 5%.This work offers necessary reference to improve microwave absorption performance by phase engineering and design a new type of flexible electromagnetic wave absorption material to apply for the portable microwave absorption electronic devices.
文摘The human foot is a very complex structure comprising numerous bones, muscles, ligaments and synovial joints. As the only component in contact with the ground, the foot complex delivers a variety of biomechanical functions during human locomotion, e.g. body support and propulsion, stability maintenance and impact absorption. These need the human foot to be rigid and damped to transmit ground reaction forces to the upper body and maintain body stability, and also to be compliant and resilient to moderate risky impacts and save energy. How does the human foot achieve these apparent conflicting functions？ In this study, we propose a phase-dependent hypothesis for the overall locomotor functions of the human foot complex based on in-vivo measurements of human natural gait and simulation results of a mathematical foot model. We propse that foot functions are highly dependent on gait phase, which is a major characteristics of human locomotion. In early stance just after heel strike, the foot mainly works as a shock absorber by moderating high impacts using the viscouselastic heel pad in both vertical and horizontal directions. In mid-stance phase （-80% of stance phase）, the foot complex can be considered as a springy rocker, reserving external mechanical work using the foot arch whilst moving ground contact point forward along a curved path to maintain body stability. In late stance after heel off, the foot complex mainly serves as a force modulator like a gear box, modulating effective mechanical advantages of ankle plantiflexor muscles using metatarsal-phalangeal joints. A sound under- standing of how diverse functions are implemented in a simple foot segment during human locomotion might be useful to gain insight into the overall foot locomotor functions and hence to facilitate clinical diagnosis, rehabilitation product design and humanoid robot development.
基金Project supported by the National Natural Science Foundation of China (Grand No. 10575055)K. C. Wong Magna Fund in Ningbo University
文摘We investigate a simple evolutionary game model in one dimension. It is found that the system exhibits a discontinuous phase transition from a defection state to a cooperation state when the b payoff of a defector exploiting a cooperator is small. Furthermore, if b is large enough, then the system exhibits two continuous phase transitions between two absorbing states and a coexistence state of cooperation and defection, respectively. The tri-critical point is roughly estimated. Moreover, it is found that the critical behavior of the continuous phase transition with an absorbing state is in the directed percolation universality class.
文摘The electrochemical performance of double phase Mg Ni alloy was characterized at 25°C and 70°C, in order to evaluate briefly its utility as negative electrode materials in nickel metal hydride batteries. The results show that the electrochemical capacity of double phase Mg Ni alloy is rarely low at 25°C, but increased rapidly when the temperature is enhanced, and the double phase Mg Ni alloy has its maximum capacity at the first discharge cycle, but the capacity degrades rapidly with cycling number.
基金supported by the Ministry of Higher under Fundamental Research Grant Scheme(No.FRGS/1/2020/TK0/UTM/02/46)Nippon Sheet Glass Grant(No.R.K130000.7343.4B818)。
文摘MXenes,drawn from MAX phases,are special two-dimensional substances with numerous advantages in nonlinear optics,specifically in giant and ultrashort pulsed-laser applications.Ti_(3)C_(2)T_(x)and Ti_(2)CT_(x)nanosheets however rapidly deteriorate under ambient conditions,limiting their applications.This paper demonstrates how excellent modulation depth of one of the MAX phase compounds vanadium zinc carbide(V_2ZnC)makes it a brilliant saturable absorber(SA)in passively Q-switched all-fiber pulsed lasers,integrated such that a 16.73-μm V_(2)ZnC-polyvinyl alcohol(PVA)thin film acts as SA in the laser.Saturable and non-saturable absorptions were found to be 13.2%and 10.47%,while saturation optical intensity and modulation depth were 6.25 k W/cm^(2)and 12.43%,respectively,illustrating the optical nonlinearity.The superiority of MAX-PVA,fabricated in four distinct ratios,was demonstrated by the fact that it self-starts a giant pulsed laser at pump power as low as 22.5 mW and firmly accomplished 120.6 kHz repetition rate with a pulse width of 2.08μs.It is a fine SA for the use of pulsed-laser production using all-fiber laser due to fabrication simplicity and great optical,thermophysical,and mechanical qualities.
