Antibacterial quaternary ammonium compounds in dental materials: A systematic review

Objective

Quaternary ammonium compounds (QACs) represent one of the most effective classes of disinfectant agents in dental materials and resin nanocomposites. This reviews aims to give a wide overview on the research in the field of antibacterial QACs in dental materials and nanocomposites.

附子和蒲公英对乌拉坦诱导肺癌小鼠中医体征的影响

目的:研究乌拉坦诱导肺癌小鼠的中医体征,观察附子和蒲公英对小鼠症状及肿瘤进展的影响.方法:每周2次、连续5周给小鼠腹腔注射乌拉坦建立小鼠肺癌模型,观察诱癌过程中小鼠外观、体温和外耳微循环变化,用能量代谢、红细胞ATP酶活性及血液流变学指标评价乌拉坦诱导肺癌小鼠的中医体征,并在模型建立同时用附子和蒲公英进行治疗,考察其对小鼠症状及肿瘤进展的影响.结果:乌拉坦诱导肺癌过程中小鼠逐渐出现畏寒喜暖、蜷缩少动、弓背毛松、体温下降、外耳和尾部血管紫暗现象,同时能量代谢和红细胞ATP酶活性降低,全血黏度及红细胞聚集指数增高.蒲公英对上述体征有增强趋势,但对肿瘤进展无影响;附子可以减弱上述体征、阻止肿瘤进展.结论:乌拉坦诱导的肺癌小鼠表现为寒凝血瘀中医体征,附子治疗能改善小鼠症状和体征,阻止肿瘤进展.     

Tailor-Made Vinylogous Urethane Vitrimers Based on Binary and Ternary Block and Random Copolymers: An Approach toward Reprocessable Materials

Vitrimers are promising reprocessable materials. To tune their properties, microphase separated block copolymers as backbones play an essential role in the thermal and mechanical properties of the resulting nanostructured networks. In this study, various narrow disperse di- and triblock copolymers containing a hydroxyethyl methacrylate block and, for comparison, random copolymers of the same comonomers are synthesized in a controlled manner by photoiniferter reversible addition-fragmentation chain transfer polymerization. Subsequently, the copolymers are modified by acetoacetate groups and cross-linked with diamines. After curing, the di- and triblock copolymer-based vitrimers exhibit excellent thermal and mechanical properties compared to random ones; moreover, their characteristic properties can be adjusted by different types and amounts of diamines. As the transamination reaction is a thermoreversible exchange reaction, the resulting vitrimers are reprocessable and therefore are recyclable materials. The combining of two of these classes of soft materials, namely vitrimers and block copolymers, leads to materials with a broad spectrum of adjustable mechanical properties for various applications with an improved end-of-life management, when compared to permanently crosslinked thermosets.