Correction: Massively Parallelized Pollen Tube Guidance and Mechanical Measurements on a Lab-on-a-Chip Platform
[This corrects the article DOI: 10.1371/journal.pone.0168138.].
ZnO nanoparticles effect on pollen grain germination and pollen tube elongation
Plant germ cells, such as pollen grains, can be affected by exposure to metal nanoparticles (NPs) that have diffused into the environment. The germination and tube elongation of pollen grain (Lilium longiflorum) exposed to low-solubility NPs was observed. The germination rate of pollen grain exposed to 100 mg L−1 ZnO NP dispersion decreased significantly from controls and exposure of the other NPs. On the other hand, when pollens were exposed to ionic solutions in which particles were removed from the 100 mg L−1 ZnO NP dispersion, the germination rates were equivalent to those in the control pollens. On the contrary, decrease of the germination rate compared to controls was small in the exposure to ZnCl2 solution, which contained a larger amount of water-soluble Zn2+ than ZnO NP dispersion. From these results, it was concluded that fine ZnO NP may adhere to pollens, due to the cohesive property of nanoparticles, and Zn2+ dissolved at the interface may be continuously absorbed by pollens. When pollen was exposed to ZnO NP, a spot with a high Ca2+ local concentration was observed at the tip of the pollen tube. On the contrary, simultaneous exposure to antagonistic ZnO NP and CaCl2 resulted in no decrease in the germination rate. From the above, it is considered that upon exposure to ZnO NP, cells absorb Zn2+ depending on the specific solubility of ZnO NP. Despite the low solubility of zinc oxide nanoparticle, pollen cell-attached particles inhibited germination and elongation of pollen tube by continuous Zn2+ dissolution from particles and Zn2+ absorption by the cell.
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.