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A porous and microstructure piezoresistive material composed of polydimethylsiloxane (PDMS) and multiwalled carbon nanotubes (MWCNTs) was designed and prepared for a flexible and highly sensitive pressure sensor over a wide detection range. The microstructure was patterned on the surface of the partially cured PDMS/MWCNTs/NaCl mixture by imprinting a nonwoven fabric. After curing and dissolving the NaCl powders, the porous and surface microstructure PDMS/MWCNT film was obtained. Two PDMS/MWCNT films were stacked together and sandwiched between two copper foil electrodes, in which the two microstructure surfaces were in contact with the electrodes. Due to the synergistic effects of the combination of the porous structure and surface microstructure, the flexible sensor had highly sensitive response over a wide pressure range from 1 Pa to 100 kPa. Under the small pressure, the high sensitivity was achieved by the change in contact areas between the electrodes and the surface microstructures; at high pressure up to 100 kPa, the sensor retained its high sensitivity because of the porous structure of the piezoresistive PDMS/MWCNT material. Additionally, the sensor had fast response speed and good durability. The piezoresistive pressure sensors based on the porous and microstructure PDMS/MWCNTs were demonstrated in detection of sound, monitoring of human activities, and array mapping of the spatial pressure distribution.

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The estrogenic pollutants 4-tert-octylphenol (OP), 4-nonylphenol (NP) and bisphenol A (BPA) were determined in surface water samples from the Haihe River, Tianjin, China. The analytes were extracted and concentrated from 300 ml acidified water samples by liquid-liquid extractions using dichloromethane, derivatized with trifluoroacetic anhydride, and quantified by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM). Among the samples collected from 14 sampling sites, only one sample was found to have a relatively high concentration of BPA (8.30 lg l À1 ) and NP (0.55 lg l À1 ). The concentrations of OP, NP and BPA in the other samples were in the range of 18.0-20.2, 106-296 and 19.1-106 ng l À1 , respectively. Recoveries for OP, NP and BPA in the spiked water samples were all over 80%.

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