With the increasing maturity of automatic driving technology,the homogeneous traffic flow will gradually evolve into the heterogeneous traffic flow,which consists of human-driving and autonomous vehicles.To better stu...With the increasing maturity of automatic driving technology,the homogeneous traffic flow will gradually evolve into the heterogeneous traffic flow,which consists of human-driving and autonomous vehicles.To better study the characteristics of the heterogeneous traffic system,this paper proposes a new car-following model for autonomous vehicles and heterogeneous traffic flow,which considers the self-stabilizing effect of vehicles.Through linear and nonlinear methods,this paper deduces and analyzes the stability of such a car-following model with the self-stabilizing effect.Finally,the model is verified by numerical simulation.Numerical results show that the self-stabilizing effect can make the heterogeneous traffic flow more stable,and that increasing the self-stabilizing coefficient or historical time length can strengthen the stability of heterogeneous traffic flow and alleviate traffic congestion effectively.In addition,the heterogeneous traffic flow can also be stabilized with a higher proportion of autonomous vehicles.展开更多
It is essential to fully understand master the traffic characteristics of the self-stabilizing control effect and roadcharacteristics to ensure the regular operation of transportation. Traffic flow on curved roads and...It is essential to fully understand master the traffic characteristics of the self-stabilizing control effect and roadcharacteristics to ensure the regular operation of transportation. Traffic flow on curved roads and slopes is irregularand more complicated than that on the straight road. However, most of the research only considers the effect ofself-stabilizing in the straight road. This study attempts to bridge this deficiency from the following three aspects.First, we review the potential influencing factors of traffic flow stability, which are related to the vehicle’s steadyvelocity, history velocity, and the turn radius of the road and the slope of the road. Based on the above review,an extended continuum model accounting for the self-stabilizing effect on a curved road with slope is proposed.Second, the linear stability criterion of the new model is derived by applying linear stability theory, and the neutralstability curve is obtained in detail. The modified KdV equation describing the evolution characteristics of trafficcongestion is derived by using the nonlinear analysis method. Upon the theoretical analysis, the third aspectfocuses on simulating the self-stabilizing effect under different slopes and radius, which demonstrates that theself-stabilizing effect is conducive to reducing congestion of the curved road with slope.展开更多
This paper presents a recovery algorithm for self-stabilizing communication protocols. It first describes some concepts and a formal description method for the algorithm. Then it proposes the algorithm procedures, pro...This paper presents a recovery algorithm for self-stabilizing communication protocols. It first describes some concepts and a formal description method for the algorithm. Then it proposes the algorithm procedures, proves its correctness and analyses its complexity. Finally, it also verifies the availability and efficiency of the algorithm by illustrating an example protocol with multi-processes.展开更多
in this paper the algorithms for self-stabilizing communication protocols are studied. First some concepts and a formal method for describing theproposed algorithms are described, then an improved algorithm for achiev...in this paper the algorithms for self-stabilizing communication protocols are studied. First some concepts and a formal method for describing theproposed algorithms are described, then an improved algorithm for achieving globalstates is presented. The study shows that the improved algorithm can be appliedto obtain the global states in the case of a loss of cooperation of the different processes in the protocol, which can be used as a recovery point that will be used bythe following recovery procedure. Thus, the improved algorithm can be used toself-stabilize a communication protocol. Meanwhile, a recovery algorithm for selfstabilizing communication protocols is presented. After a failure is detected, allProcesses can eventually know the error. The recovery algorithm uses the contextualinformation exchanged during the progress of the protocol and recorded on the stablememory. The proof of correctness and analysis of complexity for these algorithmshave been made. The availability and efficiency of the algorithms have been verifiedby illustrating the example protocols. Finally, some conclusions and remarks aregiven.展开更多
Free-standing silicon anodes with high proportion of active materials have aroused great attention;however,the mechanical stability and electrochemical performance are severely suppressed.Herein,to resolve the appeal ...Free-standing silicon anodes with high proportion of active materials have aroused great attention;however,the mechanical stability and electrochemical performance are severely suppressed.Herein,to resolve the appeal issues,a free-standing anode with a"corrugated paper"shape on micro-scale and a topological crosslinking network on the submicron and nano-scale is designed.Essentially,an integrated three-dimensional electrode structure is constructed based on robust carbon nanotubes network with firmly anchored SiNPs via forming interlocking junctions.In which,the hierarchical interlocking structure is achieved by directional induction of the binder,which ensures well integration during cycling so that significantly enhances mechanical stability as well as electronic and ionic conductivity of electrodes.Benefiting from it,this anode exhibits outsta nding performance under harsh service conditions including high Si loading,ultrahigh areal capacity(33.2 mA h cm^(-2)),and high/low temperatures(-15-60℃),which significantly extends its practical prospect.Furthermore,the optimization mechanism of this electrode is explored to verify the crack-healing and structure-integration maintaining along cycling via a unique self-stabilization process.Thus,from both the fundamental and engineering views,this strategy offers a promising path to produce high-performance free-standing electrodes for flexible device applications especially facing volume effect challenges.展开更多
In “<i>A Self-linking Field Formalism</i>” I establish a self-dual field structure with higher order self-induced symmetries that reinforce the first-order dynamics. The structure was derived from Gauss-...In “<i>A Self-linking Field Formalism</i>” I establish a self-dual field structure with higher order self-induced symmetries that reinforce the first-order dynamics. The structure was derived from Gauss-linking integrals in R<sup>3</sup> based on the Biot-Savart law and Ampere’s law applied to Heaviside’s equations, derived in strength-independent fashion in “<i>Primordial Principle of Self-Interaction</i>”. The derivation involves Geometric Calculus, topology, and field equations. My goal in this paper is to derive the simplest solution of a self-stabilized solitonic structure and discuss this model of a neutrino.展开更多
This paper discusses the algorithms for achieving global states and self-stabilizationfor communication protocols. It first describes a primary algorithm including its suitability forachieving global states and limita...This paper discusses the algorithms for achieving global states and self-stabilizationfor communication protocols. It first describes a primary algorithm including its suitability forachieving global states and limitation of self-stabilization for communication protocols, and thenpresents an improved algorithm that can be suitable to achieve global states and can be also usedto self-stabilizing communication protocols. Filially, it gives the proof of correctness and analysis ofcomplexity of the improved algorithm, and verifies its availability and efficiency by illustrating anexample protocol.展开更多
The development of PVC materials grafted with mannich base originated from myrcene(P-MAM-g,where the mannich base derived from myrcene is abbreviated as MAM)via green and effective synthetic methods is a good strategy...The development of PVC materials grafted with mannich base originated from myrcene(P-MAM-g,where the mannich base derived from myrcene is abbreviated as MAM)via green and effective synthetic methods is a good strategy to avoid unacceptable discoloration and deterioration of thermal and mechanical properties caused by autocatalytic dehydrochlorination(DHC)during PVC processing.In this study,MAM with double bonds,amino groups,ester groups,and phospholipid groups was introduced into the chains of PVC to improve the thermal stability of PVC.The experimental results showed that the covalent attachment of MAM to PVC enhanced both the initial and the long-term stability of PVC.The enhanced performance of P-MAM-g compared with unmodified PVC is attributed to the simultaneous introduction of double bonds and amino groups into the PVC structure.The double bonds trapped the unstable chlorine atoms originated from the degradation of the PVC chain and reacted with the labile macromolecular radicals originated from PVC,thus inhibiting the radical degradation of the PVC chain.Furthermore,the amino groups absorbed the HCl produced in the degradation of PVC,inhibiting the adverse effects of HCl.P-MAM-g displayed better intrinsic flexibility and anti-migration ability of organic functional components compared with the control PVC materials.A possible stabilizing mechanism of the P-MAM-g was also presented.展开更多
The additives present in polyvinyl chloride(PVC)materials are the major source of organic by-products during PVC degradation.The thermal stabilizer and plasticizer are the main additives that endow PVC with the requir...The additives present in polyvinyl chloride(PVC)materials are the major source of organic by-products during PVC degradation.The thermal stabilizer and plasticizer are the main additives that endow PVC with the required properties during its processing.However,these two additives easily migrate when samples are obtained by physical mixing of the additives with PVC.This causes the reduction of PVC sample efficacy and the increase in the formation of organic by-products in the radiolysis process.In this work,two kinds of grafted PVC samples(tungoil derivative grafted PVC and Atz grafted PVC,abbreviated as P-GT4 and P-AZ3)were synthesized by chemical grafting of 3-amino-1,2,4-triazole(Atz)and tung-oil derivative on PVC,respectively.These two PVC samples were then blended at different mass ratios to obtain hybrid PVC materials with excellent plasticization,thermal stability and migration resistance ability.Differential scanning calorimetry(DSC),discoloration,Congo red test and thermogravimetric analysis(TGA)showed that when the mass ratio of P-GT4 to P-AZ3 in the mixed PVC resin was 1:3,the resulting P1:3-GT4-AZ3(P4)presented the best plasticization and thermal stability.The kinetics of thermal decomposition showed that the activation energy of P4 was much higher than that of the reference material[PVC/DOTP/CaSt2/ZnSt2,PVC/CZ41 for short]at mass lossα=20%and 80%.In addition,the leaching test showed that P4 material possessed excellent migration resistance ability.展开更多
In order to deepen our rational understanding of Chinese characters,it is necessary to reexamine the value of it today.The reason why Chinese characters can keep vital is that it fits the unique thinking mode and aest...In order to deepen our rational understanding of Chinese characters,it is necessary to reexamine the value of it today.The reason why Chinese characters can keep vital is that it fits the unique thinking mode and aesthetic standards of the Han People.In the meantime,it intervenes in Chinese ontology by improving the resolution ratio of information trans,and objectively performs the function of the fourth element of language.展开更多
Copolymerization of propylene and hindered piperidine monomers was carried out over a high activity supported Ziegler-Natta catalyst, using Al(C2H5)(3) as cocatalyst. Factors which affect the copolymerization were stu...Copolymerization of propylene and hindered piperidine monomers was carried out over a high activity supported Ziegler-Natta catalyst, using Al(C2H5)(3) as cocatalyst. Factors which affect the copolymerization were studied, The copolymers exhibited high light stability without adding extra light stabilizers. A self-stabilized polypropylene was prepared.展开更多
The design of 1.3μm He-Ne single frequency laser for optical fiber communication is in-troduced.The scheme for obtaining steady single-mode oscillation by raising gas pressureand the method of getting linear-polariza...The design of 1.3μm He-Ne single frequency laser for optical fiber communication is in-troduced.The scheme for obtaining steady single-mode oscillation by raising gas pressureand the method of getting linear-polarization single frequency output by longitudinal Zeemaneffect are present.The relations of linewidth to some factors are discussed.展开更多
The genesis of physical particles, a foundational aspect of physics, is still a mystery. Quantum field theory creation operators provide an abstract mechanism to bring particles into existence. The assumption of a pri...The genesis of physical particles, a foundational aspect of physics, is still a mystery. Quantum field theory creation operators provide an abstract mechanism to bring particles into existence. The assumption of a primordial field underlies the Standard Model (SM), yet the forces have failed to converge to such a field. Current treatments of a superfluid-based universe [Huang, Volovik, and Svistunov, Babaev, Prokof’ev] focus heavily on vortices and Yang-Mills theory, so we analyze self-interaction of the primordial field in the context of Yang-Mills. We show that a self-stabilizing higher-order self-interaction interpretation of the Yang-Mills non-Abelian term yields a stable quantum gravity explanation of the mass-gap. In future we will address the and conserved charge aspects in terms of this fundamental theory of particle creation.展开更多
The genesis of physical particles is essentially a mystery. Quantum field theory creation operators provide an abstract mechanism by which particles come into existence, but quantum fields do not possess energy densit...The genesis of physical particles is essentially a mystery. Quantum field theory creation operators provide an abstract mechanism by which particles come into existence, but quantum fields do not possess energy density. I reference several recent treatments of this problem and develop ideas based on self-stabilizing field structures with focus on higher order self-induced self-stabilizing field structures. I extend this treatment in this paper to related issues of topological charge.展开更多
This study focuses on the behavior of chitosan(CHI)and its polyelectrolyte complexes with carboxymethyl starch(CMS)used as monolithic matrices with acetaminophen as drug tracer.Two different chitosan grades were teste...This study focuses on the behavior of chitosan(CHI)and its polyelectrolyte complexes with carboxymethyl starch(CMS)used as monolithic matrices with acetaminophen as drug tracer.Two different chitosan grades were tested alone or associated in various ratios with CMS as excipients for tablets obtained by direct compression.The degree of deacetylation(DDA)of CHI,estimated from 1H NMR and FTIR data,was correlated with X-ray diffraction and scanning electron microscopy(SEM)to evaluate structural organization of the monolithic matrices.In vitro drug dissolution assays showed major differences in CHI kinetic profiles between tablets exposed to acidic medium for 2h(to mimick gastric passage)prior to dissolution in simulated intestinal fluid(SIF),and those administered directly to SIF.Prior exposure to acidic SGF conducted to longer dissolution profiles(release completed after 16 h)and preservation of tablet shape,whereas tablets directly incubated in SIF were rapidly disintegrated.The improved properties of chitosan matrices exposed to SGF may be related to an outer compact coating layer(visible in SEM).The effect of self-stabilization of chitosan in acidic medium was compared to that due to formation of polyelectrolyte complexes(PEC)in co-processed polymeric systems(CHI:CMS).The self-formed membrane following exposure to gastric acidity appears to help maintaining tablet integrity and allows higher drug loading,recommending CHI and its complexes with CMS as excipients for drug delivery.展开更多
Electric power infrastructure has recently undergone a comprehensive transformation from electromagnetics to semiconductors. Such a development is attributed to the rapid growth of power electronic converter applicati...Electric power infrastructure has recently undergone a comprehensive transformation from electromagnetics to semiconductors. Such a development is attributed to the rapid growth of power electronic converter applications in the load side to realize energy conservation and on the supply side for renewable generations and power transmissions using high voltage direct current transmission. This transformation has altered the fundamental mechanism of power system dynamics, which demands the establishment of a new theory for power system control and protection. This paper presents thoughts on a theoretical framework for the coming semiconducting power systems.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.61773243)the Major Technology Innovation Project of Shandong Province,China(Grant No.2019TSLH0203)the National Key Research and Development Program of China(Grant No.2020YFB1600501)。
文摘With the increasing maturity of automatic driving technology,the homogeneous traffic flow will gradually evolve into the heterogeneous traffic flow,which consists of human-driving and autonomous vehicles.To better study the characteristics of the heterogeneous traffic system,this paper proposes a new car-following model for autonomous vehicles and heterogeneous traffic flow,which considers the self-stabilizing effect of vehicles.Through linear and nonlinear methods,this paper deduces and analyzes the stability of such a car-following model with the self-stabilizing effect.Finally,the model is verified by numerical simulation.Numerical results show that the self-stabilizing effect can make the heterogeneous traffic flow more stable,and that increasing the self-stabilizing coefficient or historical time length can strengthen the stability of heterogeneous traffic flow and alleviate traffic congestion effectively.In addition,the heterogeneous traffic flow can also be stabilized with a higher proportion of autonomous vehicles.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY19A010002).
文摘It is essential to fully understand master the traffic characteristics of the self-stabilizing control effect and roadcharacteristics to ensure the regular operation of transportation. Traffic flow on curved roads and slopes is irregularand more complicated than that on the straight road. However, most of the research only considers the effect ofself-stabilizing in the straight road. This study attempts to bridge this deficiency from the following three aspects.First, we review the potential influencing factors of traffic flow stability, which are related to the vehicle’s steadyvelocity, history velocity, and the turn radius of the road and the slope of the road. Based on the above review,an extended continuum model accounting for the self-stabilizing effect on a curved road with slope is proposed.Second, the linear stability criterion of the new model is derived by applying linear stability theory, and the neutralstability curve is obtained in detail. The modified KdV equation describing the evolution characteristics of trafficcongestion is derived by using the nonlinear analysis method. Upon the theoretical analysis, the third aspectfocuses on simulating the self-stabilizing effect under different slopes and radius, which demonstrates that theself-stabilizing effect is conducive to reducing congestion of the curved road with slope.
基金National Natural Science Foundation of China and NSF of Hubei Province.
文摘This paper presents a recovery algorithm for self-stabilizing communication protocols. It first describes some concepts and a formal description method for the algorithm. Then it proposes the algorithm procedures, proves its correctness and analyses its complexity. Finally, it also verifies the availability and efficiency of the algorithm by illustrating an example protocol with multi-processes.
文摘in this paper the algorithms for self-stabilizing communication protocols are studied. First some concepts and a formal method for describing theproposed algorithms are described, then an improved algorithm for achieving globalstates is presented. The study shows that the improved algorithm can be appliedto obtain the global states in the case of a loss of cooperation of the different processes in the protocol, which can be used as a recovery point that will be used bythe following recovery procedure. Thus, the improved algorithm can be used toself-stabilize a communication protocol. Meanwhile, a recovery algorithm for selfstabilizing communication protocols is presented. After a failure is detected, allProcesses can eventually know the error. The recovery algorithm uses the contextualinformation exchanged during the progress of the protocol and recorded on the stablememory. The proof of correctness and analysis of complexity for these algorithmshave been made. The availability and efficiency of the algorithms have been verifiedby illustrating the example protocols. Finally, some conclusions and remarks aregiven.
基金sponsored by the National Natural Science Foundation of China(21905221,21805221)the Suzhou Technological innovation of key industries-research and development of key technologies(SGC2021118)。
文摘Free-standing silicon anodes with high proportion of active materials have aroused great attention;however,the mechanical stability and electrochemical performance are severely suppressed.Herein,to resolve the appeal issues,a free-standing anode with a"corrugated paper"shape on micro-scale and a topological crosslinking network on the submicron and nano-scale is designed.Essentially,an integrated three-dimensional electrode structure is constructed based on robust carbon nanotubes network with firmly anchored SiNPs via forming interlocking junctions.In which,the hierarchical interlocking structure is achieved by directional induction of the binder,which ensures well integration during cycling so that significantly enhances mechanical stability as well as electronic and ionic conductivity of electrodes.Benefiting from it,this anode exhibits outsta nding performance under harsh service conditions including high Si loading,ultrahigh areal capacity(33.2 mA h cm^(-2)),and high/low temperatures(-15-60℃),which significantly extends its practical prospect.Furthermore,the optimization mechanism of this electrode is explored to verify the crack-healing and structure-integration maintaining along cycling via a unique self-stabilization process.Thus,from both the fundamental and engineering views,this strategy offers a promising path to produce high-performance free-standing electrodes for flexible device applications especially facing volume effect challenges.
文摘In “<i>A Self-linking Field Formalism</i>” I establish a self-dual field structure with higher order self-induced symmetries that reinforce the first-order dynamics. The structure was derived from Gauss-linking integrals in R<sup>3</sup> based on the Biot-Savart law and Ampere’s law applied to Heaviside’s equations, derived in strength-independent fashion in “<i>Primordial Principle of Self-Interaction</i>”. The derivation involves Geometric Calculus, topology, and field equations. My goal in this paper is to derive the simplest solution of a self-stabilized solitonic structure and discuss this model of a neutrino.
文摘This paper discusses the algorithms for achieving global states and self-stabilizationfor communication protocols. It first describes a primary algorithm including its suitability forachieving global states and limitation of self-stabilization for communication protocols, and thenpresents an improved algorithm that can be suitable to achieve global states and can be also usedto self-stabilizing communication protocols. Filially, it gives the proof of correctness and analysis ofcomplexity of the improved algorithm, and verifies its availability and efficiency by illustrating anexample protocol.
基金subsidized for the National Natural Science Foundation of China(21905117)and the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The development of PVC materials grafted with mannich base originated from myrcene(P-MAM-g,where the mannich base derived from myrcene is abbreviated as MAM)via green and effective synthetic methods is a good strategy to avoid unacceptable discoloration and deterioration of thermal and mechanical properties caused by autocatalytic dehydrochlorination(DHC)during PVC processing.In this study,MAM with double bonds,amino groups,ester groups,and phospholipid groups was introduced into the chains of PVC to improve the thermal stability of PVC.The experimental results showed that the covalent attachment of MAM to PVC enhanced both the initial and the long-term stability of PVC.The enhanced performance of P-MAM-g compared with unmodified PVC is attributed to the simultaneous introduction of double bonds and amino groups into the PVC structure.The double bonds trapped the unstable chlorine atoms originated from the degradation of the PVC chain and reacted with the labile macromolecular radicals originated from PVC,thus inhibiting the radical degradation of the PVC chain.Furthermore,the amino groups absorbed the HCl produced in the degradation of PVC,inhibiting the adverse effects of HCl.P-MAM-g displayed better intrinsic flexibility and anti-migration ability of organic functional components compared with the control PVC materials.A possible stabilizing mechanism of the P-MAM-g was also presented.
基金the National Natural Science Foundation of China(21905117)Guangxi Key Laboratory of Chemistry and Engineering of Forest Products(GXFK2203)and the Natural Science Foundation of Jiangsu Province(BK20201128)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The additives present in polyvinyl chloride(PVC)materials are the major source of organic by-products during PVC degradation.The thermal stabilizer and plasticizer are the main additives that endow PVC with the required properties during its processing.However,these two additives easily migrate when samples are obtained by physical mixing of the additives with PVC.This causes the reduction of PVC sample efficacy and the increase in the formation of organic by-products in the radiolysis process.In this work,two kinds of grafted PVC samples(tungoil derivative grafted PVC and Atz grafted PVC,abbreviated as P-GT4 and P-AZ3)were synthesized by chemical grafting of 3-amino-1,2,4-triazole(Atz)and tung-oil derivative on PVC,respectively.These two PVC samples were then blended at different mass ratios to obtain hybrid PVC materials with excellent plasticization,thermal stability and migration resistance ability.Differential scanning calorimetry(DSC),discoloration,Congo red test and thermogravimetric analysis(TGA)showed that when the mass ratio of P-GT4 to P-AZ3 in the mixed PVC resin was 1:3,the resulting P1:3-GT4-AZ3(P4)presented the best plasticization and thermal stability.The kinetics of thermal decomposition showed that the activation energy of P4 was much higher than that of the reference material[PVC/DOTP/CaSt2/ZnSt2,PVC/CZ41 for short]at mass lossα=20%and 80%.In addition,the leaching test showed that P4 material possessed excellent migration resistance ability.
文摘In order to deepen our rational understanding of Chinese characters,it is necessary to reexamine the value of it today.The reason why Chinese characters can keep vital is that it fits the unique thinking mode and aesthetic standards of the Han People.In the meantime,it intervenes in Chinese ontology by improving the resolution ratio of information trans,and objectively performs the function of the fourth element of language.
文摘Copolymerization of propylene and hindered piperidine monomers was carried out over a high activity supported Ziegler-Natta catalyst, using Al(C2H5)(3) as cocatalyst. Factors which affect the copolymerization were studied, The copolymers exhibited high light stability without adding extra light stabilizers. A self-stabilized polypropylene was prepared.
文摘The design of 1.3μm He-Ne single frequency laser for optical fiber communication is in-troduced.The scheme for obtaining steady single-mode oscillation by raising gas pressureand the method of getting linear-polarization single frequency output by longitudinal Zeemaneffect are present.The relations of linewidth to some factors are discussed.
文摘The genesis of physical particles, a foundational aspect of physics, is still a mystery. Quantum field theory creation operators provide an abstract mechanism to bring particles into existence. The assumption of a primordial field underlies the Standard Model (SM), yet the forces have failed to converge to such a field. Current treatments of a superfluid-based universe [Huang, Volovik, and Svistunov, Babaev, Prokof’ev] focus heavily on vortices and Yang-Mills theory, so we analyze self-interaction of the primordial field in the context of Yang-Mills. We show that a self-stabilizing higher-order self-interaction interpretation of the Yang-Mills non-Abelian term yields a stable quantum gravity explanation of the mass-gap. In future we will address the and conserved charge aspects in terms of this fundamental theory of particle creation.
文摘The genesis of physical particles is essentially a mystery. Quantum field theory creation operators provide an abstract mechanism by which particles come into existence, but quantum fields do not possess energy density. I reference several recent treatments of this problem and develop ideas based on self-stabilizing field structures with focus on higher order self-induced self-stabilizing field structures. I extend this treatment in this paper to related issues of topological charge.
文摘This study focuses on the behavior of chitosan(CHI)and its polyelectrolyte complexes with carboxymethyl starch(CMS)used as monolithic matrices with acetaminophen as drug tracer.Two different chitosan grades were tested alone or associated in various ratios with CMS as excipients for tablets obtained by direct compression.The degree of deacetylation(DDA)of CHI,estimated from 1H NMR and FTIR data,was correlated with X-ray diffraction and scanning electron microscopy(SEM)to evaluate structural organization of the monolithic matrices.In vitro drug dissolution assays showed major differences in CHI kinetic profiles between tablets exposed to acidic medium for 2h(to mimick gastric passage)prior to dissolution in simulated intestinal fluid(SIF),and those administered directly to SIF.Prior exposure to acidic SGF conducted to longer dissolution profiles(release completed after 16 h)and preservation of tablet shape,whereas tablets directly incubated in SIF were rapidly disintegrated.The improved properties of chitosan matrices exposed to SGF may be related to an outer compact coating layer(visible in SEM).The effect of self-stabilization of chitosan in acidic medium was compared to that due to formation of polyelectrolyte complexes(PEC)in co-processed polymeric systems(CHI:CMS).The self-formed membrane following exposure to gastric acidity appears to help maintaining tablet integrity and allows higher drug loading,recommending CHI and its complexes with CMS as excipients for drug delivery.
基金This work was supported in part by the National Basic Research Program of China (973 Program) (Grant No. 2012CB215100), and the Major Program of the National Natural Science Foundation of China (Grant No. 51190104).
文摘Electric power infrastructure has recently undergone a comprehensive transformation from electromagnetics to semiconductors. Such a development is attributed to the rapid growth of power electronic converter applications in the load side to realize energy conservation and on the supply side for renewable generations and power transmissions using high voltage direct current transmission. This transformation has altered the fundamental mechanism of power system dynamics, which demands the establishment of a new theory for power system control and protection. This paper presents thoughts on a theoretical framework for the coming semiconducting power systems.