An on-site direct detection method for paraquat in biologic fluids was developed on the basis of iodidefacilitated pinhole shell-isolated nanoparticle-enhanced Raman spectroscopy. A full removal of matrix interference on the nanoparticle surface from the complicated biologic samples, and a selective attraction of paraquat to "hotspot" via a highly electrostatic adsorption on the iodide-modified nanoparticle surface are accomplished in this method. Four distinguished characteristics were provided as (1) high sensitivity with a limit of detection of 1 mg L À1 for paraquat; (2) free of pretreatment with a direct measurement in plasma or urine finished within 1 minute; (3) on-site detection using a portable Raman spectrometer; and (4) high antifouling stability during measurement with the pinhole shellisolated nanoparticle structure. This method was further showed its great clinical diagnosis applicability on a rapid, accurate detection of the plasma and urine samples from a paraquat poisoned patient. Fig. 5 SERS spectra of the urine (a) and plasma (b) of the paraquat poisoned patient and of saline solution (c). Both urine and plasma samples were diluted 100 times by saline solution.This journal is
Phosgene and its analogs are greatly harmful to the public health, environmental safety and homeland security as widely used industrial substances with extremely high toxicity. In order to rapidly evaluate the emergency risk caused by these chemicals, a new highly sensitive method based on surface-enhanced Raman spectroscopy (SERS) technique for measurement of phosgene agents was developed for the first time. Coupled with a chemical transformation approach, the highly toxic phosgene was conveniently converted to a SERS-sensitive probe, i.e. iodine (I 2 ), with low toxicity or non-toxicity. The characteristic SERS peak in 459 cm À1 was used for quantitation and was presumed as a formation of triiodide anion (I 3 À ), which was induced in an iodide (I À )-aggregation Au NPs system. The total measurement can be completed in~20 min with the limits of detection of~60 μg/l (phosgene) and~30 μg/l (diphosgene), respectively, on a portable Raman spectrometer. This work is the first report of SERS measurement on phosgene and diphosgene in a quantitative level. This method is expected to meet the requirements of on-site detection of phosgene agents, promote emergency responses and raise more opportunities for the portable SERS applications.
The concepts on σ‐hole and π‐hole bonds are suggested. A cocrystal with repeated 8‐F‐atom unit as basic structural motif is assembled based on bifurcated CI···N···IC halogen/σ‐hole bond and antiparallel double π‐hole···F bonds by 1,2‐diiodotetrafluorobenzene and acridine and characterized well by XRD, powder XRD and solid 19F NMR, etc. Also the calculated interaction energies are −26.8 and −31.5 kJ/mol for bifurcated CI···N sp2 halogen bonds, and −14.3 kJ/mol for a pair of π‐hole···F bonds. In this system CI···N halogen bond has stronger competitive ability to CI···π halogen bond due to stronger basicity of N than π‐system in acridine. The combination of the halogen/σ‐hole and π‐hole bonds or together with other weak interactions could play a key role in assembling function materials, molecular recognition and design of drugs and so on.
As the best representative of the current cutting-edge technology, unmanned aerial vehicle (UAV) is widely used in various fields such as electric power inspection, agriculture, forestry and plant protection, fire rescue, and film and television shooting. With the rapid development of UAV, the safety work of UAV has become more important. In order to improve the safety of hexarotor UAV during flight, a fault-tolerant control scheme independent of basic control law and control distribution is designed in this paper. Firstly, the linear active disturbance rejection control (LADRC) was used as the basic control law for attitude control of hexarotor UAV. Secondly, in the case of actuator failure of hexarotor UAV, a fault observer was used to estimate fault information accurately. Then, on this basis, the control distribution matrix was adjusted to reduce the use of the faulty motor, and the purpose of fault-tolerant control was achieved. Finally, simulation experiments and actual flight experiments were carried out to verify the effectiveness of the proposed scheme. Experimental results show that the proposed scheme can improve the robustness of the control system and the flight safety of UAV.
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