利用乙酸钠和柠檬酸钠对ZSM-5分子筛进行脱硅改性处理,并通过XRD、SEM、NH_(3)-TPD、^(27)Al MAS NMR、吡啶吸附红外光谱和N2吸附-脱附等表征手段对ZSM-5分子筛结构、酸量、比表面积及孔体积等物化性质进行表征分析。结果表明,碱改性使...利用乙酸钠和柠檬酸钠对ZSM-5分子筛进行脱硅改性处理,并通过XRD、SEM、NH_(3)-TPD、^(27)Al MAS NMR、吡啶吸附红外光谱和N2吸附-脱附等表征手段对ZSM-5分子筛结构、酸量、比表面积及孔体积等物化性质进行表征分析。结果表明,碱改性使分子筛的孔径增加且形成合适的微-介孔结构,同时,使L酸量和B酸量明显降低。当乙酸钠溶液浓度为0.5 mol/L时,改性的分子筛在形成大量介孔结构的同时具有合适的B/L值,使催化剂的寿命延长并展现出最优的催化性能。与微孔ZSM-5相比,使用寿命由20 h延长到74 h,芳烃最高产率从20.97%提高到40.05%。展开更多
Two types of floating pellets in stomach were prepared. The first one: floating alginate pellets containing ethylcellulose and clarithromycin (AE)were pellets with dispersed ethylcellulose in the alginate gel matrix. ...Two types of floating pellets in stomach were prepared. The first one: floating alginate pellets containing ethylcellulose and clarithromycin (AE)were pellets with dispersed ethylcellulose in the alginate gel matrix. The second one:ethylcellulose microspheres containing clarithromycin (Em) were first prepared by the emulsion solvent diffusion method, and then alginate pellets containing ethylcellulose microspheres (AEm) were prepared. The effects of processing parameters on morphology, size distribution, drug loading, in vitro drug release profiles, in vitro floating property of pellets were investigated. The results showed that about 80% of drug incorporated in AE was released at 2 h, while AEm with moderate drug content had sustained drug release property. The accumulative drug-release percent of AEm in vitro at 6 h were 65.9%—78.8%, and AEm could float in acetate buffer solution for more than 8 h.展开更多
文摘Two types of floating pellets in stomach were prepared. The first one: floating alginate pellets containing ethylcellulose and clarithromycin (AE)were pellets with dispersed ethylcellulose in the alginate gel matrix. The second one:ethylcellulose microspheres containing clarithromycin (Em) were first prepared by the emulsion solvent diffusion method, and then alginate pellets containing ethylcellulose microspheres (AEm) were prepared. The effects of processing parameters on morphology, size distribution, drug loading, in vitro drug release profiles, in vitro floating property of pellets were investigated. The results showed that about 80% of drug incorporated in AE was released at 2 h, while AEm with moderate drug content had sustained drug release property. The accumulative drug-release percent of AEm in vitro at 6 h were 65.9%—78.8%, and AEm could float in acetate buffer solution for more than 8 h.
文摘以利用新一代城市大气扩散模型系统(ADMS-Urban)模拟的二氧化硫浓度为基础,测算锦州市城区空气中SO2环境容量.通过建立锦州市城区SO2排放清单、建立空气质量扩散模型,模拟不同污染物排放量的环境质量状况,同时结合环境规划的实际做相应的削减计划,使各功能区控制目标分别达到国家一类区、二类区标准,从而确定锦州市城区大气中SO2实际环境容量.测算结果表明,锦州市城区大气SO2实际环境容量为45 520 t.
