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 synthesized very pure dimer phase of coroneae by simple heat-treatment and subsequent sublimation purification. It was confirmed by laser desorption/ionization mass spectroscopy measurements that pure dime...The authors synthesized very pure dimer phase of coroneae by simple heat-treatment and subsequent sublimation purification. It was confirmed by laser desorption/ionization mass spectroscopy measurements that pure dimer phase of coronenes can be obtained by controlling the fusing and sublimation temperatures. The crystal structure of the dimer phase was analyzed by synchrotron XRD （X-ray diffraction） experiments. It was also found that very bright red light is emitted by irradiating ultra violet light （λ = 350 nm） to the dimer phase. The external and internal quantum yields were determined to be 5.56% and 6.95%, respectively.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.
文摘The authors synthesized very pure dimer phase of coroneae by simple heat-treatment and subsequent sublimation purification. It was confirmed by laser desorption/ionization mass spectroscopy measurements that pure dimer phase of coronenes can be obtained by controlling the fusing and sublimation temperatures. The crystal structure of the dimer phase was analyzed by synchrotron XRD （X-ray diffraction） experiments. It was also found that very bright red light is emitted by irradiating ultra violet light （λ = 350 nm） to the dimer phase. The external and internal quantum yields were determined to be 5.56% and 6.95%, respectively.
