钢筋砼结构防水施工

通过五个地下工程的防水施工实例介绍了充分利用砼结构自防水性能作法和一套施工措施,以满足地下工程对防水的质量控制要求。     

Preparation, characterization and in vitro release of chitosan-stavudine conjugate nano-prodrug

Chitosan-stavudine (d4T) conjugate with a succinic spacer was synthesized via carbodiimide coupling reaction and structurally characterized. In order to nanosize it for improving its therapeutic properties, the chitosan-5′-O-succinyl-d4T conjugate was crosslinked with sodium tripolyphosphate (TPP) to obtain the chitosan-d4T conjugate nano-prodrug. The morphologies of chitosan-d4T conjugate nanoparticles were observed by transmission electron microscopy (TEM), and their zeta potential, particle size, and polydispersity (size distribution) were measured by the dynamic light scattering (DLS) techniques. In vitro drug release studies at pH 1.1 and pH 7.4 indicate that the crosslinked chitosan-d4T conjugate nano-prodrug can prevent the coupled d4T from leaking out before entering the target viral reservoirs and provide a mild sustained release without the burst release. The results reveal that constructing conjugated chitosan nano-prodrugs may be a promising approach for improving the therapy efficacy of drugs in antiviral treatment.     

公斤级阿维巴坦钠的合成工艺

用药物合成设计手段对阿维巴坦钠的合成工艺进行改进,并实现公斤级规模放大.以廉价易得的L-焦谷氨酸为原料,经酯化、叔丁氧羰基保护、硫叶立德开环、苄氧胺盐酸盐缩合、脱叔丁氧羰基、合成哌啶环、构建5位手性碳、异构体拆分得到高纯度草酸盐.草酸盐经氨解、分子内脲化、脱苄基、磺酸酯化、成季铵盐和钠离子交换反应得到阿维巴坦钠.工艺反应条件温和,后处理操作简便,更绿色环保.实现了阿维巴坦钠公斤级制备工艺,总收率19.7％,HPLC纯度99.81％.     

公斤级阿维巴坦钠的合成工艺

摘要：用药物合成设计手段对阿维巴坦钠的合成工艺进行改进并实现公斤级规模放大。以廉价易得的L-焦谷氨酸为原料,经酯化、叔丁氧羰基保护、硫叶立德开环、苄氧胺盐酸盐缩合、脱叔丁氧羰基、合成哌啶环、构建5位手性碳、异构体拆分得到高纯度草酸盐。草酸盐经氨解、分子内脲化、脱苄基、磺酸酯化、成季铵盐和钠离子交换反应得到阿维巴坦钠。本工艺反应条件温和,后处理操作简便,工艺更绿色。实现阿维巴坦钠公斤级制备工艺,总收率19.7%,HPLC纯度99.8%。