Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium ...Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium carbonate tablets are carried out at various temperatures.The dissolution process of each tablet is measured by electrical conductivity tracking method and the concentration of dissolved sodium carbonate is quanti fied with calibrated conductivity-concentration converting equation of sodium carbonate.The quanti fied dissolution data is fitted with both surface reaction model and diffusion layer model and the results clearly show that surface reaction model is suggested as the appropriate dissolution model for all measured tablets.Therefore,it is determined that carboxymethyl cellulose is a stable element to remain the dissolution mechanism of tablet unchanged.The dissolution rate constant quanti fied with surface reaction model presents that carboxymethyl cellulose-sodium carbonate two-component tablets obtain signi ficant higher dissolution rate constant than pure sodium carbonate tablet and higher proportion of carboxymethyl cellulose leads to apparent higher dissolution rate constant.The results prove for the usage of carboxymethyl cellulose in most practical applications at a relative low-level,the effect of carboxymethyl cellulose is effective and positive for two-component tablet to enhance the dissolution process and improve dissolution rate constant and this effect is speculated coming from its dynamic physical transforming process in water including dilation and conglutination.展开更多
The authors presented a facile approach to prepare highly-ordered sub-micrometer scaled cylindrical diamond arrays based on a chemical vapor deposition method,where the accurate control of the style of crystal seeds d...The authors presented a facile approach to prepare highly-ordered sub-micrometer scaled cylindrical diamond arrays based on a chemical vapor deposition method,where the accurate control of the style of crystal seeds dispersion and the growth time are very crucial.The as-prepared diamond array showed good conductivity which was originated from the proper boron doping,and moreover,it exhibited good field emission property with low turn-on field and high emission current.Importantly,this approach can be easily applied to the preparation of various micro-patterned one-dimensional diamond arrays.展开更多
基金the Institute of Particle and Science Engineering,University of Leeds and Procter & Gamble Newcastle Innovation Centre(UK) for partially funding the project
文摘Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium carbonate tablets are carried out at various temperatures.The dissolution process of each tablet is measured by electrical conductivity tracking method and the concentration of dissolved sodium carbonate is quanti fied with calibrated conductivity-concentration converting equation of sodium carbonate.The quanti fied dissolution data is fitted with both surface reaction model and diffusion layer model and the results clearly show that surface reaction model is suggested as the appropriate dissolution model for all measured tablets.Therefore,it is determined that carboxymethyl cellulose is a stable element to remain the dissolution mechanism of tablet unchanged.The dissolution rate constant quanti fied with surface reaction model presents that carboxymethyl cellulose-sodium carbonate two-component tablets obtain signi ficant higher dissolution rate constant than pure sodium carbonate tablet and higher proportion of carboxymethyl cellulose leads to apparent higher dissolution rate constant.The results prove for the usage of carboxymethyl cellulose in most practical applications at a relative low-level,the effect of carboxymethyl cellulose is effective and positive for two-component tablet to enhance the dissolution process and improve dissolution rate constant and this effect is speculated coming from its dynamic physical transforming process in water including dilation and conglutination.
基金Supported by the National Natural Science Foundation of China(Nos.20601005,20125102 and 20571077)the National Basic Research Program of China(Nos.2010CB934700,2009CB930404 and 2007CB936403)+1 种基金the Special Fund for Special Prize of the President Awardthe Chinese Postdoctoral Fund and K. C. Wong Education Foundation
文摘The authors presented a facile approach to prepare highly-ordered sub-micrometer scaled cylindrical diamond arrays based on a chemical vapor deposition method,where the accurate control of the style of crystal seeds dispersion and the growth time are very crucial.The as-prepared diamond array showed good conductivity which was originated from the proper boron doping,and moreover,it exhibited good field emission property with low turn-on field and high emission current.Importantly,this approach can be easily applied to the preparation of various micro-patterned one-dimensional diamond arrays.
