Hydrothermal ore zoning is a transport-reaction problem in which infiltration is the principal Prcness of transport and dissolution/Precipitation is the Principal process of chemical reactions.Neglecting diffusion an...Hydrothermal ore zoning is a transport-reaction problem in which infiltration is the principal Prcness of transport and dissolution/Precipitation is the Principal process of chemical reactions.Neglecting diffusion and ion exchange/adsorption would not affect the basic attributes of hydrothermal ore zoning. Hydrothermal ore zoning belongs essentially to infiltration metasomatic zoning, it results from the formation and propagation of dissolution/precipitation waves through Permeable media. The authors apply the theory of coupled infiltration and dissolution/precipitation reactions in Physicochemical hydrodynamics to studying the structural characteristics of dissolution/precipitation waves, and apply furthermore the coherence principle in dynamic theory of multicomponent coupled systems to revealing the dynamic mechanisms of their formation. The results of investigation verify and develop . C. 's theory of infiltration metasomatic zoning,on the one hand, raising it from the qualitative, equilibrium thermodynamic basis to the quantitative dynamic level;on the other hand, and more importantly, applying theories of Physicochemical hydrodynamics and dynamics of multicomponent coupled systems to bringing to light the dynamic mechanisms of formation of the structure of hydrothermal ore zoning, and advancing a theory of hydrothermal ore zoning, putting forward new ideas on the nature of the problem of hydrothermal ore zoning, the essence of hydrothermal ore zoning and the structural characteristics and mechanisms of formation of hydrothermal ore zoning.展开更多
Cancer is a genetic disease characterized by heritable defects in cellular regulatory mechanisms.Tumor cells must adapt their metabolism to survive and proliferate in the challenging conditions of the tumor microenvir...Cancer is a genetic disease characterized by heritable defects in cellular regulatory mechanisms.Tumor cells must adapt their metabolism to survive and proliferate in the challenging conditions of the tumor microenvironment.To maintain uncontrolled cellular growth and survival,cancer cells alter their metabolism,which makes them dependent on a steady supply of nutrients and energy.Almost a century ago,the Warburg theory suggested that cancer cells consume glucose even in the presence of oxygen.Recent studies have confirmed that cancer cells indeed consume significantly more glucose than normal cells.Cancerous tumors require an acidic microenvironment with low oxygen levels for growth and spread.However,recent advances in pH measurement have shown that the intracellular pH of cancer cells is neutral or slightly alkaline compared to normal tissue cells.This finding indicates that not all tumors are highly acidic.Taking advantage of cancer cells’high glucose consumption,a strategy to lyse cancer cells is tested by means of glucose modifications that exploit the characteristics of their uncontrolled growth process.From the study of the molecular structure to give him alkaline properties that enable him to make defects in the tumor structure and possibly achieve cell killing,this situation will have a killing effect on cancer cells if small molecules of toxic atoms(alkaline atoms)can be continuously supplied to them through food,due to the uncontrolled consumption of glucose molecules by cancer cells.This theory attempts to investigate by changing the atomic structure of glucose molecules to make them alkaline glucosodiene molecules as one of the methods to kill cancer cells.By preparing alkaline glucosodiene molecules and performing animal experiments and histological observations,it was shown that tumors without alkaline treatment showed a tendency to infiltrate and grow,while tumors treated with glucosodiene molecules showed complete disappearance of cell structure and nucleolysis,supporting the validity of the theory.展开更多
The degradation of Pt nanoparticles （NPs） in fuel cell cathodes leads to the loss of the precious metal catalyst. While the effect of NP size on Pt dissolution has been studied extensively, the influence of NP shape...The degradation of Pt nanoparticles （NPs） in fuel cell cathodes leads to the loss of the precious metal catalyst. While the effect of NP size on Pt dissolution has been studied extensively, the influence of NP shape is largely unexplored. Because of the recent development of experimental methods to control the shape of metal NPs, rational guidelines/insights on the shape effects on NP stability are imperative. In this study, first-principles calculations based on density functional theory were conducted to determine the stability of 1-2 nm Pt NPs against Pt dissolution and coalescence with respect to NP shape. Toward dissolution, the stability of the Pt NPs increases in the following order： Hexagonal close-packed 〈 icosahedral 〈 cuboctahedral 〈 truncated octahedral. This trend is attributed to the synergy of the oxygen adsorption strength and the local coordination of the Pt atoms. With respect to coalescence, the size of a NP is related to its propensity to coalesce or detach/migrate to form larger particles. The stability of the Pt NPs was found to increase in the following order： Hexagonal close-packed 〈 truncated octahedral 〈 cuboctahedral 〈 icosahedral, and was correlated with the cohesive energies of the particles. By combining the characteristic stabilities of the shapes, new ＂metal-interfaced＂ Pt-based coreshell architectures were proposed that should be more stable than pure Pt nanoparticles with respect to both dissolution and coalescence.展开更多
文摘Hydrothermal ore zoning is a transport-reaction problem in which infiltration is the principal Prcness of transport and dissolution/Precipitation is the Principal process of chemical reactions.Neglecting diffusion and ion exchange/adsorption would not affect the basic attributes of hydrothermal ore zoning. Hydrothermal ore zoning belongs essentially to infiltration metasomatic zoning, it results from the formation and propagation of dissolution/precipitation waves through Permeable media. The authors apply the theory of coupled infiltration and dissolution/precipitation reactions in Physicochemical hydrodynamics to studying the structural characteristics of dissolution/precipitation waves, and apply furthermore the coherence principle in dynamic theory of multicomponent coupled systems to revealing the dynamic mechanisms of their formation. The results of investigation verify and develop . C. 's theory of infiltration metasomatic zoning,on the one hand, raising it from the qualitative, equilibrium thermodynamic basis to the quantitative dynamic level;on the other hand, and more importantly, applying theories of Physicochemical hydrodynamics and dynamics of multicomponent coupled systems to bringing to light the dynamic mechanisms of formation of the structure of hydrothermal ore zoning, and advancing a theory of hydrothermal ore zoning, putting forward new ideas on the nature of the problem of hydrothermal ore zoning, the essence of hydrothermal ore zoning and the structural characteristics and mechanisms of formation of hydrothermal ore zoning.
文摘Cancer is a genetic disease characterized by heritable defects in cellular regulatory mechanisms.Tumor cells must adapt their metabolism to survive and proliferate in the challenging conditions of the tumor microenvironment.To maintain uncontrolled cellular growth and survival,cancer cells alter their metabolism,which makes them dependent on a steady supply of nutrients and energy.Almost a century ago,the Warburg theory suggested that cancer cells consume glucose even in the presence of oxygen.Recent studies have confirmed that cancer cells indeed consume significantly more glucose than normal cells.Cancerous tumors require an acidic microenvironment with low oxygen levels for growth and spread.However,recent advances in pH measurement have shown that the intracellular pH of cancer cells is neutral or slightly alkaline compared to normal tissue cells.This finding indicates that not all tumors are highly acidic.Taking advantage of cancer cells’high glucose consumption,a strategy to lyse cancer cells is tested by means of glucose modifications that exploit the characteristics of their uncontrolled growth process.From the study of the molecular structure to give him alkaline properties that enable him to make defects in the tumor structure and possibly achieve cell killing,this situation will have a killing effect on cancer cells if small molecules of toxic atoms(alkaline atoms)can be continuously supplied to them through food,due to the uncontrolled consumption of glucose molecules by cancer cells.This theory attempts to investigate by changing the atomic structure of glucose molecules to make them alkaline glucosodiene molecules as one of the methods to kill cancer cells.By preparing alkaline glucosodiene molecules and performing animal experiments and histological observations,it was shown that tumors without alkaline treatment showed a tendency to infiltrate and grow,while tumors treated with glucosodiene molecules showed complete disappearance of cell structure and nucleolysis,supporting the validity of the theory.
文摘The degradation of Pt nanoparticles （NPs） in fuel cell cathodes leads to the loss of the precious metal catalyst. While the effect of NP size on Pt dissolution has been studied extensively, the influence of NP shape is largely unexplored. Because of the recent development of experimental methods to control the shape of metal NPs, rational guidelines/insights on the shape effects on NP stability are imperative. In this study, first-principles calculations based on density functional theory were conducted to determine the stability of 1-2 nm Pt NPs against Pt dissolution and coalescence with respect to NP shape. Toward dissolution, the stability of the Pt NPs increases in the following order： Hexagonal close-packed 〈 icosahedral 〈 cuboctahedral 〈 truncated octahedral. This trend is attributed to the synergy of the oxygen adsorption strength and the local coordination of the Pt atoms. With respect to coalescence, the size of a NP is related to its propensity to coalesce or detach/migrate to form larger particles. The stability of the Pt NPs was found to increase in the following order： Hexagonal close-packed 〈 truncated octahedral 〈 cuboctahedral 〈 icosahedral, and was correlated with the cohesive energies of the particles. By combining the characteristic stabilities of the shapes, new ＂metal-interfaced＂ Pt-based coreshell architectures were proposed that should be more stable than pure Pt nanoparticles with respect to both dissolution and coalescence.
