The chemical stability of simulated waste forms Zr_（1–x）Nd_xSiO_（4–x/2） was investigated using the static leach test（MCC-1） with lixiviants of three pH values（pH=4, 6.7 and 10） at three temperature points（4...The chemical stability of simulated waste forms Zr_（1–x）Nd_xSiO_（4–x/2） was investigated using the static leach test（MCC-1） with lixiviants of three pH values（pH=4, 6.7 and 10） at three temperature points（40, 90 and 150 oC） for periods ranging from 1 to 42 d, and the influence of temperature, pH, as well as their combined effects were explored in detail. The results showed that all the normalized release rate of Nd firstly decreased with leaching time and closed to equilibrium after 14 d. As the temperature increased, the normalized release rate of Nd also increased, but it was no more than 3×10^（–5） g/（m^2·d）. And, the normalized release rate of Nd reached the highest values（~5×10^（–5） g/（m^2·d）） when pH=4, whilst the normalized release rate of Nd remained the lowest value（~1×10^（–5） g/（m^2·d）） near neutral environment（pH=6.7）.展开更多
Thermal interface materials(TIMs)play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR).The TCR between the solid–liquid contact surface is much...Thermal interface materials(TIMs)play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR).The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface,but conventional solid–liquid phase change materials are likely to cause serious leakage.Therefore,this work has prepared a new formstable phase change thermal interface material.Through the melt blending of paraffin wax(PW)and low-density polyethylene(LDPE),the stability is improved and it has an excellent coating effect on PW.The addition of aluminum(Al)powder improves the low thermal conductivity of PW/LDPE,and the addition of 15wt%Al powder improves the thermal conductivity of the internal structure of the matrix by 67%.In addition,the influence of the addition of Al powder on the internal structure,thermal properties,and phase change behavior of the PW/LDPE matrix was systematically studied.The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties,and the thermal conductivity increased with the increase of Al addition.Therefore,morphologically stable PW/LDPE/Al is an important development direction for TIMs.展开更多
Since the ratio-dependent theory reflects the fact that predators must share and compete for food, it is suitable for describing the relationship between predators and their preys and has recently become a very import...Since the ratio-dependent theory reflects the fact that predators must share and compete for food, it is suitable for describing the relationship between predators and their preys and has recently become a very important theory put forward by biologists. In order to investigate the dynamical relationship between predators and their preys, a so-called Michaelis-Menten ratio-dependent predator-prey model is studied in this paper with gestation time delays of predators and preys taken into consideration. The stability of the positive equilibrium is investigated by the Nyquist criteria, and the existence of the local Hopf bifurcation is analyzed by employing the theory of Hopf bifurcation. By means of the center manifold and the normal form theories, explicit formulae are derived to determine the stability, direction and other properties of bifurcating periodic solutions. The above theoretical results are validated by numerical simulations with the help of dynamical software WinPP. The results show that if both the gestation delays are small enough, their sizes will keep stable in the long run, but if the gestation delays of predators are big enough, their sizes will periodically fluc-tuate in the long term. In order to reveal the effects of time delays on the ratio-dependent predator-prey model, a ratiodependent predator-prey model without time delays is considered. By Hurwitz criteria, the local stability of positive equilibrium of this model is investigated. The conditions under which the positive equilibrium is locally asymptotically stable are obtained. By comparing the results with those of the model with time delays, it shows that the dynamical behaviors of ratio-dependent predator-prey model with time delays are more complicated. Under the same conditions, namely, with the same parameters, the stability of positive equilibrium of ratio-dependent predator-prey model would change due to the introduction of gestation time delays for predators and preys. Moreover, with the variation of time delays, the positive equilibrium of the ratio-dependent predator-prey model subjects to Hopf bifurcation.展开更多
The solid forms of drugs play a central role in controlling their physicochemical properties and consequently the bioavailability. Multiple types of drug solid forms have been developed to achieve the desirable pharma...The solid forms of drugs play a central role in controlling their physicochemical properties and consequently the bioavailability. Multiple types of drug solid forms have been developed to achieve the desirable pharmaceutical profiles, but new solid forms will provide more options for the solid-state property optimization and hence are highly desirable. This review focuses on a new pharmaceutical solid form, drug-polymer inclusion complexes （ICs）, and summarizes their structural features, structure- property relationships, as well as potential pharmaceutical applications展开更多
The solid form of drugs plays a central role in optimizing the physicochemical properties of drugs,and new solid forms will provide more options to achieve the desirable pharmaceutical profiles of drugs.Recently,certa...The solid form of drugs plays a central role in optimizing the physicochemical properties of drugs,and new solid forms will provide more options to achieve the desirable pharmaceutical profiles of drugs.Recently,certain drugs have been found to form crystalline inclusion complexes（ICs） with multiple types of linear polymers,representing a new subcategory of pharmaceutical solids.In this study,we used diflunisal（DIF） as the model drug host and extended the vip of drug/polymer ICs from homopolymers to block copolymers of poly（ethylene glycol）（PEG） and poly（s-caprolactone）（PCL）.The block length in the vip copolymers showed a significant influence on the formation,thermal stability and dissolution behavior of the DIF ICs.Though the PEG block could hardly be included alone,it could indeed be included in the DIF ICs when the PCL block was long enough.The increase of the PCL block length produced IC crystals with improved thermal stability.The dissolution profiles of DIF/block copolymer ICs exhibited gradually decreased aqueous solubility and dissolution rate with the increasing PCL block length.These results demonstrate the possibility of using drug/polymer ICs to modulate the desired pharmaceutical profiles of drugs in a predictable and controllable manner.展开更多
Toxicity studies considering both the bare and stabilized forms of zero valent iron nanoparticles（nZVI） could be timely, given that ecological risks identified are minimized through modification or with substitution...Toxicity studies considering both the bare and stabilized forms of zero valent iron nanoparticles（nZVI） could be timely, given that ecological risks identified are minimized through modification or with substitution of approaches in the synthesis, development and environmental application of the nanoparticles before succeeding to volume production.This review is focused on the fate, transport and toxicological implications of the bare nZVI and surface modified particles used for environmental applications.展开更多
This paper devotes to rational design for the ship propellers with long wavy blades. Thin long blades create big elastic deformations, which can be a regulator of an optimum angle for attack. The wavy form provides st...This paper devotes to rational design for the ship propellers with long wavy blades. Thin long blades create big elastic deformations, which can be a regulator of an optimum angle for attack. The wavy form provides stability on operational modes. To ensure stabilization to decrease in bending and torsion fluctuations, the main sectorial coordinates were defined by combining the shift centre with the gravity centre for computer geometrical models of the rowing screw blade and an idealized elastic deformable boundary liquid flow layer while unit thickness was offered. More rational petal forms of the long blade with a wavy surface are explained for exception of not free torsion.展开更多
Selecting a site for a nuclear power plant requires extensive studies to ensure its safety and stability during its operation until its decommissioning. The 4,500-year old Egyptian pyramids at Giza are buildings to le...Selecting a site for a nuclear power plant requires extensive studies to ensure its safety and stability during its operation until its decommissioning. The 4,500-year old Egyptian pyramids at Giza are buildings to learn from. This paper tries to pin down the reasons for the survival of the Giza pyramids in order to reach a criterion for choosing sites for important buildings. It argues that the site selection and the geological properties of the area, being away from seismic effects,, floods and groundwater levels, the stability of the geometric form of the pyramid, the solidity of the structural engineering and precision of execution arguably are the reasons why the Great Pyramids of Giza are the only survivors of the seven wonders of the ancient world.展开更多
This paper investigates the stability analysis and H_∞ control for a class of nonlinear timedelay systems,and proposes a number of new results.Firstly,an equivalent form is given for this class of systems by means of...This paper investigates the stability analysis and H_∞ control for a class of nonlinear timedelay systems,and proposes a number of new results.Firstly,an equivalent form is given for this class of systems by means of coordinate transformation and orthogonal decomposition of vector fields.Then,based on the equivalent form,some delay-dependent results are derived for the stability analysis of the systems by constructing a novel Lyapunov functional.Thirdly,the authors use the equivalent form and the obtained stability results to investigate the H_∞ control problem for a class of nonhnear time-delay control systems,and present a control design procedure.Finally,an illustrative example is given to show the effectiveness of the results obtained in this paper.It is shown that the main results of this paper are easier to check than some existing ones,and have less conservatism.展开更多
基金Project supported by the National Natural Science Foundation of China(41302028,41302029,21507105)Thousand Youth Talents Plan(Y42H831301)+3 种基金Key Project of Sichuan Education Department(14ZA0099,15ZB0116)Foundation of Laboratory of National Defense Key Discipline for Nuclear Waste and Environmental Safety,Southwest University of Science and Technology(15yyhk10)the Doctor Foundation in Southwest University of Science and Technology(10zx7126)Hebei Science and Technology Support Program(15211121)
文摘The chemical stability of simulated waste forms Zr_（1–x）Nd_xSiO_（4–x/2） was investigated using the static leach test（MCC-1） with lixiviants of three pH values（pH=4, 6.7 and 10） at three temperature points（40, 90 and 150 oC） for periods ranging from 1 to 42 d, and the influence of temperature, pH, as well as their combined effects were explored in detail. The results showed that all the normalized release rate of Nd firstly decreased with leaching time and closed to equilibrium after 14 d. As the temperature increased, the normalized release rate of Nd also increased, but it was no more than 3×10^（–5） g/（m^2·d）. And, the normalized release rate of Nd reached the highest values（~5×10^（–5） g/（m^2·d）） when pH=4, whilst the normalized release rate of Nd remained the lowest value（~1×10^（–5） g/（m^2·d）） near neutral environment（pH=6.7）.
基金supported by the National Natural Science Foundation of China,China(No.51874047)the Key Science and Technology Project of Changsha City,China(No.kq2102005)+1 种基金the Special Fund for the Construction of Innovative Province in Hunan Province,China(No.2020RC3038)the Changsha City Fund for Distinguished and Innovative Young Scholars,China(No.kq1802007)。
文摘Thermal interface materials(TIMs)play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR).The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface,but conventional solid–liquid phase change materials are likely to cause serious leakage.Therefore,this work has prepared a new formstable phase change thermal interface material.Through the melt blending of paraffin wax(PW)and low-density polyethylene(LDPE),the stability is improved and it has an excellent coating effect on PW.The addition of aluminum(Al)powder improves the low thermal conductivity of PW/LDPE,and the addition of 15wt%Al powder improves the thermal conductivity of the internal structure of the matrix by 67%.In addition,the influence of the addition of Al powder on the internal structure,thermal properties,and phase change behavior of the PW/LDPE matrix was systematically studied.The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties,and the thermal conductivity increased with the increase of Al addition.Therefore,morphologically stable PW/LDPE/Al is an important development direction for TIMs.
基金supported by the National Natural Science Foundation of China (10702065 and 10532050)China National Funds for Distinguished Young Scientists (10625211)the Program of Shanghai Subject Chief Scientist (08XD14044)
文摘Since the ratio-dependent theory reflects the fact that predators must share and compete for food, it is suitable for describing the relationship between predators and their preys and has recently become a very important theory put forward by biologists. In order to investigate the dynamical relationship between predators and their preys, a so-called Michaelis-Menten ratio-dependent predator-prey model is studied in this paper with gestation time delays of predators and preys taken into consideration. The stability of the positive equilibrium is investigated by the Nyquist criteria, and the existence of the local Hopf bifurcation is analyzed by employing the theory of Hopf bifurcation. By means of the center manifold and the normal form theories, explicit formulae are derived to determine the stability, direction and other properties of bifurcating periodic solutions. The above theoretical results are validated by numerical simulations with the help of dynamical software WinPP. The results show that if both the gestation delays are small enough, their sizes will keep stable in the long run, but if the gestation delays of predators are big enough, their sizes will periodically fluc-tuate in the long term. In order to reveal the effects of time delays on the ratio-dependent predator-prey model, a ratiodependent predator-prey model without time delays is considered. By Hurwitz criteria, the local stability of positive equilibrium of this model is investigated. The conditions under which the positive equilibrium is locally asymptotically stable are obtained. By comparing the results with those of the model with time delays, it shows that the dynamical behaviors of ratio-dependent predator-prey model with time delays are more complicated. Under the same conditions, namely, with the same parameters, the stability of positive equilibrium of ratio-dependent predator-prey model would change due to the introduction of gestation time delays for predators and preys. Moreover, with the variation of time delays, the positive equilibrium of the ratio-dependent predator-prey model subjects to Hopf bifurcation.
基金supported by the National Natural Science Foundation of China (No. 21434008)
文摘The solid forms of drugs play a central role in controlling their physicochemical properties and consequently the bioavailability. Multiple types of drug solid forms have been developed to achieve the desirable pharmaceutical profiles, but new solid forms will provide more options for the solid-state property optimization and hence are highly desirable. This review focuses on a new pharmaceutical solid form, drug-polymer inclusion complexes （ICs）, and summarizes their structural features, structure- property relationships, as well as potential pharmaceutical applications
基金financially supported by the National Natural Science Foundation of China(Nos.21434008,21374054)National Basic Research Program of China(973 Program,No.2014CB932202)
文摘The solid form of drugs plays a central role in optimizing the physicochemical properties of drugs,and new solid forms will provide more options to achieve the desirable pharmaceutical profiles of drugs.Recently,certain drugs have been found to form crystalline inclusion complexes（ICs） with multiple types of linear polymers,representing a new subcategory of pharmaceutical solids.In this study,we used diflunisal（DIF） as the model drug host and extended the vip of drug/polymer ICs from homopolymers to block copolymers of poly（ethylene glycol）（PEG） and poly（s-caprolactone）（PCL）.The block length in the vip copolymers showed a significant influence on the formation,thermal stability and dissolution behavior of the DIF ICs.Though the PEG block could hardly be included alone,it could indeed be included in the DIF ICs when the PCL block was long enough.The increase of the PCL block length produced IC crystals with improved thermal stability.The dissolution profiles of DIF/block copolymer ICs exhibited gradually decreased aqueous solubility and dissolution rate with the increasing PCL block length.These results demonstrate the possibility of using drug/polymer ICs to modulate the desired pharmaceutical profiles of drugs in a predictable and controllable manner.
文摘Toxicity studies considering both the bare and stabilized forms of zero valent iron nanoparticles（nZVI） could be timely, given that ecological risks identified are minimized through modification or with substitution of approaches in the synthesis, development and environmental application of the nanoparticles before succeeding to volume production.This review is focused on the fate, transport and toxicological implications of the bare nZVI and surface modified particles used for environmental applications.
文摘This paper devotes to rational design for the ship propellers with long wavy blades. Thin long blades create big elastic deformations, which can be a regulator of an optimum angle for attack. The wavy form provides stability on operational modes. To ensure stabilization to decrease in bending and torsion fluctuations, the main sectorial coordinates were defined by combining the shift centre with the gravity centre for computer geometrical models of the rowing screw blade and an idealized elastic deformable boundary liquid flow layer while unit thickness was offered. More rational petal forms of the long blade with a wavy surface are explained for exception of not free torsion.
文摘Selecting a site for a nuclear power plant requires extensive studies to ensure its safety and stability during its operation until its decommissioning. The 4,500-year old Egyptian pyramids at Giza are buildings to learn from. This paper tries to pin down the reasons for the survival of the Giza pyramids in order to reach a criterion for choosing sites for important buildings. It argues that the site selection and the geological properties of the area, being away from seismic effects,, floods and groundwater levels, the stability of the geometric form of the pyramid, the solidity of the structural engineering and precision of execution arguably are the reasons why the Great Pyramids of Giza are the only survivors of the seven wonders of the ancient world.
基金supported by the National Natural Science Foundation of China under Grant Nos.G60774009,61074068,61034007,61374065,and 61304033the Research Fund for the Doctoral Program of Chinese Higher Education under Grant No.200804220028+1 种基金the Natural Science Foundation of Shandong Province under Grant Nos.ZR2013ZEM006,ZR2011EL021,BS2011ZZ012,2013ZRB01873Colleges and Universities in Shandong Province Science and Technology Project under Grant Nos.J13LN37 and J12LN29
文摘This paper investigates the stability analysis and H_∞ control for a class of nonlinear timedelay systems,and proposes a number of new results.Firstly,an equivalent form is given for this class of systems by means of coordinate transformation and orthogonal decomposition of vector fields.Then,based on the equivalent form,some delay-dependent results are derived for the stability analysis of the systems by constructing a novel Lyapunov functional.Thirdly,the authors use the equivalent form and the obtained stability results to investigate the H_∞ control problem for a class of nonhnear time-delay control systems,and present a control design procedure.Finally,an illustrative example is given to show the effectiveness of the results obtained in this paper.It is shown that the main results of this paper are easier to check than some existing ones,and have less conservatism.
