Sodium azide is a widely used inorganic compound. Besides the commonly used method of ＂Wislicenus process＂ which uses ammonia, nitrous and sodium as materials, the hydrazine hydrate route is also employed for the pr...Sodium azide is a widely used inorganic compound. Besides the commonly used method of ＂Wislicenus process＂ which uses ammonia, nitrous and sodium as materials, the hydrazine hydrate route is also employed for the preparation of sodium azide particularly in laboratory. However, because many species are involved in the reaction system, the reaction details for the hydrazine hydrate route are still unclear. A comprehensive understanding of the reaction mechanism may provide meaningful help for optimizing the production process. In this work, the reaction mechanism for the synthesis of sodium azide by hydrazine hydrate route has been studied using density function theory（DFT） method. On the basis of our calculations, the reaction details, including the energetics of ten elementary steps, the structures of intermediates and transition states as well as the influence of inorganic acids and alcohols, were illuminated at the atomistic level. Both the two steps, the generation of key intermediate（NH2-NH-NO） and the trans-cistransformation of NH2-NH-NO, are suggested to be the possible rate-limiting step, corresponding to the energy barriers of 20.3 and 22.7 kcal/mol, respectively. In the early reaction steps to generate NH2-NH-NO, the main role of sulphuric acid is to donate proton, which can be replaced by nitric acid or hydrochloric acid. From the energy point of view, isopropanol has similar reactivity as methanol and ethanol.展开更多
A novel redox-responsive PEG-sheddable copolymer of disulfide-linked polyethylene glycol 5000-lysine-di-tocopherol succinate(P_(5k)SSLV)was designed and synthesized.Thin-film hydration method was used to prepare DOX-l...A novel redox-responsive PEG-sheddable copolymer of disulfide-linked polyethylene glycol 5000-lysine-di-tocopherol succinate(P_(5k)SSLV)was designed and synthesized.Thin-film hydration method was used to prepare DOX-loaded P_(5k)SSLV nanomicelle.To optimize the preparation technology,we investigate the effects of dosage,type of organic solvent,hydration temperature and time,and cryoprotectant on drug-loading content,encapsulation efficiency,particle size,and zeta potential.The mean particle size and zeta potential were determined by Zetasizer.The morphology of the P_(5k)SSLV-DOX nanomicelles was visualized by transmission electron microscopy.The drug-loading content and encapsulation efficiency of P_(5k)SSLV-DOX nanomicelle were investigated by UV.The drug-loading content,encapsulation efficiency,particle size,and zeta potential of the final optimized nanomicelles were 4.58%,97.20%,30.21 nm and -0.84 mV,respectively.In addition,the stability of nanomicelles was investigated,which included dilution stability and storage stability.The results showed that P_(5k)SSLV-DOX nanomicelle had good dilution stability and storage stability at 4℃.The preparation method of P_(5k)SSLV-DOX nanomicelle with thinfilm hydration method was practical and simple,which was valuable to be further studied.展开更多
Dear Editor,In a recent interventional case report,Allon et al ）hydrated corneal stroma with cefuroxime to seal a small traumatic leaky corneal perforation that was unresponsive to prior soft bandage contact lens app...Dear Editor,In a recent interventional case report,Allon et al ）hydrated corneal stroma with cefuroxime to seal a small traumatic leaky corneal perforation that was unresponsive to prior soft bandage contact lens application for 6d.展开更多
The preparation of Nd(OH)3 powder by the direct hydration method using Nd2O3 as a raw material was studied,and the effects of stirring mode,H2O and Nd2O3 molar ratio,stirring rate,and reaction time on temperature chan...The preparation of Nd(OH)3 powder by the direct hydration method using Nd2O3 as a raw material was studied,and the effects of stirring mode,H2O and Nd2O3 molar ratio,stirring rate,and reaction time on temperature change and conversion rate in a hydration system were analyzed.The reasonable process conditions for the direct hydration of Nd(OH)3 by Nd2O3 were then determined.Process,morphology,and structure were considered in the preparation of neodymium hydroxide powder,and its composition was investigated by X-ray powder diffraction,scanning electron microscopy,laser particle size analysis,thermogravimetric differential thermal analysis,and chemical analysis.It has been proved that the process is simple and feasible,in line with the concept of modern green chemistry,and the products also meet the market requirements.展开更多
基金supported by the National Natural Science Foundation of China(21773138)
文摘Sodium azide is a widely used inorganic compound. Besides the commonly used method of ＂Wislicenus process＂ which uses ammonia, nitrous and sodium as materials, the hydrazine hydrate route is also employed for the preparation of sodium azide particularly in laboratory. However, because many species are involved in the reaction system, the reaction details for the hydrazine hydrate route are still unclear. A comprehensive understanding of the reaction mechanism may provide meaningful help for optimizing the production process. In this work, the reaction mechanism for the synthesis of sodium azide by hydrazine hydrate route has been studied using density function theory（DFT） method. On the basis of our calculations, the reaction details, including the energetics of ten elementary steps, the structures of intermediates and transition states as well as the influence of inorganic acids and alcohols, were illuminated at the atomistic level. Both the two steps, the generation of key intermediate（NH2-NH-NO） and the trans-cistransformation of NH2-NH-NO, are suggested to be the possible rate-limiting step, corresponding to the energy barriers of 20.3 and 22.7 kcal/mol, respectively. In the early reaction steps to generate NH2-NH-NO, the main role of sulphuric acid is to donate proton, which can be replaced by nitric acid or hydrochloric acid. From the energy point of view, isopropanol has similar reactivity as methanol and ethanol.
文摘A novel redox-responsive PEG-sheddable copolymer of disulfide-linked polyethylene glycol 5000-lysine-di-tocopherol succinate(P_(5k)SSLV)was designed and synthesized.Thin-film hydration method was used to prepare DOX-loaded P_(5k)SSLV nanomicelle.To optimize the preparation technology,we investigate the effects of dosage,type of organic solvent,hydration temperature and time,and cryoprotectant on drug-loading content,encapsulation efficiency,particle size,and zeta potential.The mean particle size and zeta potential were determined by Zetasizer.The morphology of the P_(5k)SSLV-DOX nanomicelles was visualized by transmission electron microscopy.The drug-loading content and encapsulation efficiency of P_(5k)SSLV-DOX nanomicelle were investigated by UV.The drug-loading content,encapsulation efficiency,particle size,and zeta potential of the final optimized nanomicelles were 4.58%,97.20%,30.21 nm and -0.84 mV,respectively.In addition,the stability of nanomicelles was investigated,which included dilution stability and storage stability.The results showed that P_(5k)SSLV-DOX nanomicelle had good dilution stability and storage stability at 4℃.The preparation method of P_(5k)SSLV-DOX nanomicelle with thinfilm hydration method was practical and simple,which was valuable to be further studied.
文摘Dear Editor,In a recent interventional case report,Allon et al ）hydrated corneal stroma with cefuroxime to seal a small traumatic leaky corneal perforation that was unresponsive to prior soft bandage contact lens application for 6d.
基金financial support for this study by the Natural Science Foundation of Inner Mongolia(CN)(2016ZD05)。
文摘The preparation of Nd(OH)3 powder by the direct hydration method using Nd2O3 as a raw material was studied,and the effects of stirring mode,H2O and Nd2O3 molar ratio,stirring rate,and reaction time on temperature change and conversion rate in a hydration system were analyzed.The reasonable process conditions for the direct hydration of Nd(OH)3 by Nd2O3 were then determined.Process,morphology,and structure were considered in the preparation of neodymium hydroxide powder,and its composition was investigated by X-ray powder diffraction,scanning electron microscopy,laser particle size analysis,thermogravimetric differential thermal analysis,and chemical analysis.It has been proved that the process is simple and feasible,in line with the concept of modern green chemistry,and the products also meet the market requirements.
