Sulfur dioxide (SO 2 ) is one of the most dangerous air pollutants that impair environment and human health. SO 2 in air is released during the burning of fossil fuels and plays one major role in the formation of acid rain. The repeated exposure to low levels of SO 2 can cause permanent pulmonary impairment for humans. [ 1 ] The long and short-term exposure limits for SO 2 gas are 2 and 5 ppm, respectively, [ 1 , 2 ] and the U. S. Environmental Control Agency has set the acceptable limit for SO 2 in ambient air at a level of 0.5 ppm. [ 3 ] It is of great importance to measure low concentration of SO 2 in air accurately and fast for human health protection and air-quality monitoring.Semiconductor resistor sensors are, for more than 30 years, one of the most common used gas sensors to detect toxic and fl ammable gases such as NO 2 , H 2 S, CO, NH 3 , and H 2 because of their distinguished merits such as low cost, long lasting, high sensitivity, and good reliability, etc. [ 4 ] Organic fi eld-effect transistor (OFET) is another alternative semiconductor sensing technology with advantages over resistors, and has attracted much attention only recently. [ 5 ] The sensitivity can be dramatically enhanced by changing the source-drain current ( I SD ) of OFET when operating the sensors in the sub-threshold regime, as a result of the current modulation by the extra gate electrode. [ 6 ] Another advantage of OFET sensors is that the sensing response can be enhanced by integrating them in oscillator and adaptive amplifi er circuits. [ 7 ] These advantages combined with low cost and light weight of organic semiconductors ensure that OFET sensors have attracted much attention for the detection of a wide range of gases. [ 8 ] However, only few efforts have been made to develop the semiconductor SO 2 sensors and almost all of them are resistortype (a detailed performance list for the reported semiconductor SO 2 sensors is shown in Supporting Information Table S1). The semiconductor materials are mainly focused on metal oxide, such as SnO 2 , WO 3 and TiO 2 . Most reported semiconductor SO 2 sensors require an operating temperature of 200-600 ° C, demonstrate a sensitivity lower than 50%, face challenges in low concentration detection, or suffer from a slow response and recovery time of over 10 min.In this communication, an OFET based on gas dielectric and CuPc single crystalline nanowire as a novel SO 2 sensor with complete recovery and room-temperature detection is reported.To the best of our knowledge, this is the fi rst demonstration of SO 2 gas sensing based on OFETs. The sensitivity is characterized by the enhanced fi eld-effect mobility and is as high as 764% in 20 ppm SO 2 . The detect limitation is down to sub-ppm levels (0.5 ppm) with high sensitivity (119%) and high resolution (100 ppb). The exposed conductive channel is shown to be responsible for the sensitivity to SO 2 . Figure 1 a shows a schematic image of the gas dielectric fi eldeffect transistor (FET) sensor based on CuPc nanowire and the adsorption of SO 2 ...

The effects of zinc oxide nanoparticles (ZnO NPs) on the root growth, root apical meristem mitosis and mitotic aberrations of garlic (Allium sativum L.) were investigated. ZnO NPs caused a concentration-dependent inhibition of root length. When treated with 50 mg/L ZnO NPs for 24 h, the root growth of garlic was completely blocked. The 50% inhibitory concentration (IC(50)) was estimated to be 15 mg/L. The mitosis index was also decreased in a concentration- and time-dependent manner. ZnO NPs also induced several kinds of mitotic aberrations, mainly consisted of chromosome stickiness, bridges, breakages and laggings. The total percentage of abnormal cells increased with the increase of ZnO NPs concentration and the prolongation of treatment time. The investigation provided new information for the possible genotoxic effects of ZnO NPs on plants.

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NaYF 4 :Yb 3+ /Er 3+ /polyvinylpyrrolidone (PVP) upconversion (UC) luminescent nanotubes were synthesized by the electrospinning technique. The diameters of the nanotubes were controllable by changing the electrospinning voltages. The structure and the optical properties were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectra, and fluorescence microscope. The NaYF 4 :Yb 3+ /Er 3+ /PVP nanocomposites simultaneously possessed UC luminescent property, active surfaces and tubular structure. PVP molecules were found to have an important influence on the UC luminescence of NaYF 4 :Yb 3+ /Er 3+ /PVP nanotubes. Compared with those in pure NaYF 4 :Yb 3+ /Er 3+ nanoparticles, the relative intensities of violet, blue, and green to red emissions were increased in NaYF 4 :Yb 3+ /Er 3+ /PVP nanotubes. It is owing to the existence of PVP molecules, which might produce the passivation on NaYF 4 :Yb 3+ /Er 3+ nanoparticles and reduce the nonradiative relaxation of Er 3+ ion. The luminescent nanotubes with desirable UC properties are expected to be applied in biomedicine.