The aim of this study was to design porous matrix beads for floating drug delivery using enteric polymer, Eudragit~? L and various amounts of waxes(0, 0.1, 0.5, 1, 2 and 3% w/w). In this study, wax containing cetyl al...The aim of this study was to design porous matrix beads for floating drug delivery using enteric polymer, Eudragit~? L and various amounts of waxes(0, 0.1, 0.5, 1, 2 and 3% w/w). In this study, wax containing cetyl alcohol and white petrolatum was utilized to produce pores using a wax removal technique. To prepare the beads, Eudragit~? L, metronidazole and wax were dissolved in acetone and then extruded into dichloromethane. The effect of the amount of wax on the floating and drug release behavior of the Eudragit~? L beads was determined.After the extruded product was immersed in dichloromethane, wax dissolved out from the formed beads, resulting in a porous structure. The prepared beads could float in simulated gastric fluid for more than 10 hours. Different amounts of wax had an effect on the drug release. We found that when the percentage of wax increased, the drug release was higher while the beads remained floating. The results suggest that Eudragit~? L beads could be used as a carrier for an intragastric floating drug delivery system.展开更多
The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments...The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments applying the sequencing batch reactor（SBR） activated sludge process to domestic wastewater with low C/N ratio. The addition of sodium chloride（NaCI） to influent was established to achieve nitrite build-up. The high nitrite accumulation, depending on the salinity in influent and the application duration of salt, was obtained in SBRs treating saline wastewater. The maintenance results indicated that the real-time SBRs can maintain stable nitrite accumulation, but conversion from shorter nitrification-denitrification to full nitrification-denitrification was observed after some operation cycles in the other SBR with fixed-time control. The presented method is valuable to offer a solution to realize and to maintain nitrogen removal via nitrite under normal conditions.展开更多
The denitrifying sulfide removal(DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate species into di-nitrogen gas, elementa...The denitrifying sulfide removal(DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate species into di-nitrogen gas, elemental sulfur and carbon dioxide, respectively, at high loading rates. This study has determined that the reaction rate of sulfide oxidized into sulfur could be enhanced in the presence of 1,2-naphthoquinone-4-sulphonate(NQS). The presence of NQS mitigated the inhibition effects of sulfide species on denitrification. Furthermore, the reaction rates of nitrate and acetate to nitrogen gas and CO_2, respectively, were also promoted in the presence of NQS, thereby enhancing the performance of DSR granules. The advantages and disadvantages of applying the NQS-DSR process are discussed.展开更多
基金the Faculty of Pharmacy, Silpakorn University for financial support
文摘The aim of this study was to design porous matrix beads for floating drug delivery using enteric polymer, Eudragit~? L and various amounts of waxes(0, 0.1, 0.5, 1, 2 and 3% w/w). In this study, wax containing cetyl alcohol and white petrolatum was utilized to produce pores using a wax removal technique. To prepare the beads, Eudragit~? L, metronidazole and wax were dissolved in acetone and then extruded into dichloromethane. The effect of the amount of wax on the floating and drug release behavior of the Eudragit~? L beads was determined.After the extruded product was immersed in dichloromethane, wax dissolved out from the formed beads, resulting in a porous structure. The prepared beads could float in simulated gastric fluid for more than 10 hours. Different amounts of wax had an effect on the drug release. We found that when the percentage of wax increased, the drug release was higher while the beads remained floating. The results suggest that Eudragit~? L beads could be used as a carrier for an intragastric floating drug delivery system.
基金The Hi_Tech Research and Development Program(863) of China(2004AA601020) the National Natural Science Foundation of China(No.50478047)andthe Open Grant of Beijing Key Laboratory
文摘The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments applying the sequencing batch reactor（SBR） activated sludge process to domestic wastewater with low C/N ratio. The addition of sodium chloride（NaCI） to influent was established to achieve nitrite build-up. The high nitrite accumulation, depending on the salinity in influent and the application duration of salt, was obtained in SBRs treating saline wastewater. The maintenance results indicated that the real-time SBRs can maintain stable nitrite accumulation, but conversion from shorter nitrification-denitrification to full nitrification-denitrification was observed after some operation cycles in the other SBR with fixed-time control. The presented method is valuable to offer a solution to realize and to maintain nitrogen removal via nitrite under normal conditions.
基金supported bythe National Natural Science Foundation of China under Grant No. 21307160the Natural Science Foundation of Shandong Province under Grant No. ZR2013EEQ030
文摘The denitrifying sulfide removal(DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate species into di-nitrogen gas, elemental sulfur and carbon dioxide, respectively, at high loading rates. This study has determined that the reaction rate of sulfide oxidized into sulfur could be enhanced in the presence of 1,2-naphthoquinone-4-sulphonate(NQS). The presence of NQS mitigated the inhibition effects of sulfide species on denitrification. Furthermore, the reaction rates of nitrate and acetate to nitrogen gas and CO_2, respectively, were also promoted in the presence of NQS, thereby enhancing the performance of DSR granules. The advantages and disadvantages of applying the NQS-DSR process are discussed.
