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Abstract A novel nano-sized imprinted polymer/multi-walled carbon nanotube (MWCNTs)-based potentiometric sensor is introduced for lactic acid (LA) sensing in dairy products. The imprinted polymer was synthesized using allyl amine (AA) and ethylene glycol dimethacrylate as functional monomer and cross-linker, respectively. It was demonstrated that the amide linkage was created between LA and AA during copolymerization reaction which was finally hydrolyzed when removing template from the synthesized MIP. It was also shown that the MIP cavities, compatible with LA anion, were created during polymerization reaction which influenced the potentiometric response behavior of the MIP-based electrode. This novel potentiometric sensor is a carbon rod electrode, coated with a membrane consisting of the MIP nanoparticles (2.5%), MWCNTs (2%), dibutylphthalate (DBP) (65%), poly-vinyl chloride (PVC) (28.5%) and tetra phenyl phosphonium bromide (TPPB) (2%). The active ion sensed by the electrode is the LA anion formed at elevated pH condition. The sensor exhibited Nernstian slope of 30.3 ± 0.4 mVdecade−1 in the working concentration range of 1.0 × 10−1to 1.0 × 10−6 mol L−1 with detection limit of 7.3 × 10−7 mol L−1. The sensor displayed a stable potential response in the pH range of 5–8 and fast response time of less than 60 s. It exhibited also high selectivity over the interfering species. The proposed sensor was successfully applied for the determination of LA in real samples (milk and yoghurt). Graphical abstract fx1 Highlights • A new nano-sized imprinted polymer was synthesized for lactic acid recognition. • Ally amine was used as the functional monomer for LA imprinting. • LA-MIP was used as ionophore of the membrane coated graphite rod electrode. • Including of MWCNTs in the membrane improved the electrode performance. • The electrode exhibited response time of 60 s and DL of detection limit of 0.73 µM. [ABSTRACT FROM AUTHOR]

This paper constructs a comprehensive evaluation system of human settlements focusing on housing conditions, urban natural environments, social economy, and public infrastructure. Principal Component Analysis and Cluster Analysis are used to analyze and rank the 2003–2013 human settlements index and create five clusters for 35 major cities in China (including municipalities, provincial capitals, and Prefecture-level cities). On the basis of four years of a spatial analysis of the human settlements index, we find that living conditions of 35 Chinese cities have significantly improved; severe air pollution persists in China, with large differences between the north and the south; weak correlation between urban human settlements and the growth rate of economic development; and the infrastructure of China's mega cities is overloaded. The results confirm and quantify growing geographic disparities and deep structural urban challenges that are associated with rapid economic growth and social change, leaving many cities in China to struggle with worsening pollution, excessive demand on existing infrastructures, and housing prices that rise faster than disposable incomes. [ABSTRACT FROM AUTHOR]