The growth mechanism of spectinomycin dihydrochloride crystal in pure water and acetone-water mixture at different temperatures has been studied by induction period measurement. The induction period was measured visua...The growth mechanism of spectinomycin dihydrochloride crystal in pure water and acetone-water mixture at different temperatures has been studied by induction period measurement. The induction period was measured visually. The solid-liquid interfacial tension was determined on the basis of classical homogenous nucleation theory and the surface entropy factor was calculated. It was shown that the interfacial tension and surface entropy factor increased with the increase of acetone concentration and the decrease of temperature. It was demonstrated that the growth mechanism of spectinomycin dihydrochloride crystal was controlled by birth and spread growth in pure water or in acetone-water mixture at high temperatures and turned from birth and spread growth to spiral growth with the increase of acetone concentration in acetone-water mixture at low temperatures.展开更多
By using idealized numerical simulations, the impact of tropical cyclone size on secondary eyewall formation（SEF） is examined. Both unbalanced boundary layer and balanced processes are examined to reveal the underly...By using idealized numerical simulations, the impact of tropical cyclone size on secondary eyewall formation（SEF） is examined. Both unbalanced boundary layer and balanced processes are examined to reveal the underlying mechanism. The results show that a tropical cyclone（TC） with a larger initial size favors a quicker SEF and a larger outer eyewall. For a TC with a larger initial size, it will lead to a stronger surface entropy flux, and thus more active outer convection. Meanwhile, a greater inertial stability helps the conversion from diabatic heating to kinetic energy.Furthermore, the progressively broadening of the tangential wind field will induce significant boundary layer imbalances. This unbalanced boundary layer process results in a supergradient wind zone that acts as an important mechanism for triggering and maintaining deep convection. In short, different behaviors of balanced and unbalanced processes associated with the initial wind profile lead to different development rates of the secondary eyewall.展开更多
文摘The growth mechanism of spectinomycin dihydrochloride crystal in pure water and acetone-water mixture at different temperatures has been studied by induction period measurement. The induction period was measured visually. The solid-liquid interfacial tension was determined on the basis of classical homogenous nucleation theory and the surface entropy factor was calculated. It was shown that the interfacial tension and surface entropy factor increased with the increase of acetone concentration and the decrease of temperature. It was demonstrated that the growth mechanism of spectinomycin dihydrochloride crystal was controlled by birth and spread growth in pure water or in acetone-water mixture at high temperatures and turned from birth and spread growth to spiral growth with the increase of acetone concentration in acetone-water mixture at low temperatures.
基金Supported by the National Natural Science Foundation of China(41575056,41730961,and 41775058)National(Key)Basic Research and Development(973)Program of China(2015CB452803)
文摘By using idealized numerical simulations, the impact of tropical cyclone size on secondary eyewall formation（SEF） is examined. Both unbalanced boundary layer and balanced processes are examined to reveal the underlying mechanism. The results show that a tropical cyclone（TC） with a larger initial size favors a quicker SEF and a larger outer eyewall. For a TC with a larger initial size, it will lead to a stronger surface entropy flux, and thus more active outer convection. Meanwhile, a greater inertial stability helps the conversion from diabatic heating to kinetic energy.Furthermore, the progressively broadening of the tangential wind field will induce significant boundary layer imbalances. This unbalanced boundary layer process results in a supergradient wind zone that acts as an important mechanism for triggering and maintaining deep convection. In short, different behaviors of balanced and unbalanced processes associated with the initial wind profile lead to different development rates of the secondary eyewall.
