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Aeromagnetic survey of multi-rotor UAV is widely used in small and medium-sized mineral resources survey, engineering investigation, non-explosive detection and other fields due to its advantages of high safety, low cost and convenient operation. The original data of UAV aeromagnetic survey includes interference from external environment, interference from UAV platform and interference from airborne electromagnetic equipment. The interference is mainly shown as striping anomaly along the direction of the survey line in the aeromagnetic anomaly map, which affects the accuracy of aeromagnetic compensation and information detection of geological anomaly body, thus affecting the accuracy of interpretation of geological anomaly body. In this paper, the algorithm of Variational Modal Decomposition (VMD) is introduced to filter and preprocess the aeromagnetic data to obtain high quality aeromagnetic data. At the same time, the source and characteristics of the errors are predicted according to the interference size and spectrum characteristics of the Modal function errors, which provides a reference for the optimization of aeromagnetic system.

A sensitive and selective high-performance liquid chromatography-tandam mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantification of sildenafil and its metabolite N-desmethyl sildenafil in human plasma. Sildenafil-d8 was used as an internal standard. The analytes were extracted by precipitation extraction and chromatographed on a C18 column using mobile phase A of water (containing 0.1% formic acid) and mobile phase B of acetonitrile (containing 0.1% formic acid) with gradient elution. Quantification was done using multiple reaction monitoring mode to monitor the precursor-to-product ion transitions of m/z 475.4 → m/z 283.3 for sildenafil, m/z 461.4 → m/z 283.2 for N-desmethyl sildenafil and m/z 483.3 → m/z 108.1 for IS in positive ionization mode. The calibration curve was established over the range of 2.00-1,000 ng/ml and the correlation coefficient was >0.99. The intra-day and inter-day relative standard deviations were

This study is aimed at obtaining (K,Na)NbO3 powders with wide grain size distribution methods. (K,Na)NbO3 powders were successfully synthesized by different ways, including hydrothermal method, sol-gel method, and molten-salt method. The experiment results showed that the hydrothermal and sol-gel methods could not control the grain size of the (K,Na)NbO3 powders effectively . The grain size of (K,Na)NbO3 powders can be only tailored by the molten-salt method through controlling the starting oxide powder morphology, as well as crystallization temperature. The grain size was not affected by the experimental parameters whether or not the initial powders were milled. Furthermore, it has been found that the crystallization temperature could change the grain size of the powders monotonously. The (K,Na)NbO3 powders synthesized by molten salt method distributed from nanoscale to micron level, which can lay the foundation for further research on the grain size effect of (K,Na)NbO3 lead free piezoelectric ceramics.

A strong desire for environmental protection and human health care urgently requires us to find an environmental friendly type of piezoelectric material to replace the lead ones. In this study, (LixK0.5-xNa0.5)(Nb0.97Sb0.03)O3-1mol%CuO (x = 0, 0.05, 0.1 ,0.2 ,0.5, abbreviated as CuO-LxKNNS) lead-free piezoelectric ceramics have been fabricated by a conventional solid-state reaction route. We focused on the comparison of buried powder sintering with exposed sintering. The effect of buried powder sintering method on density, structure and dielectric, piezoelectric properties of CuO-LxKNNS ceramics has been investigated. It was found that the density increased greatly when the buried powder sintering method was used, which was effective in inhibiting the volatilization of alkali metal oxides compared with exposed sintering method. Piezoelectric and dielectric properties showed a similar tendency with the density. These ceramics showed an obvious phase transition with increasing the Li content. CuO-LxKNNS ceramics showed orthorhombic symmetry when x= 0, but turned to be tetragonal symmetry when x ≥ 0.05. The optimal composition of CuO-LxKNNS with buried powder sintering method was x = 0.05 sintered at 1020 °C, for which the maximum value of the piezoelectric constant (d33) was 180pC/N, the density (ρ) was 4.40g/cm3, the room temperature relative dielectric constant (εr) was 270 and the dielectric loss (tanδ) was 0.07.

Anthocyanidin synthase (ANS, leucoanthocyanidin oxygenase), a 2-oxoglutarate iron-dependent oxygenase, catalyzed the penultimate step in the biosynthesis of the anthocyanin class of flavonoids, from the colorless leucoanthocyanidins to the colored anthocyanidins. The full-length cDNA and genomic DNA sequences of ANS gene (designated as GbANS) were isolated from Ginkgo biloba for the first time. The full-length cDNA of GbANS contained a 1062-bp open reading frame (ORF) encoding a 354-amino-acid protein. The genomic DNA analysis showed that GbANS gene had three exons and two introns. The deduced GbANS protein showed high identities to other plant ANSs. The conserved amino acids (H-X-D) ligating ferrous iron and residues (R-X-S) participating in 2-oxoglutarate binding were found in GbANS at the similar positions like other ANSs. Southern blot analysis indicated that GbANS belonged to a multi-gene family. The expression analysis by real-time PCR showed that GbANS expressed in a tissue-specific manner in G. biloba. GbANS was also found to be up-regulated by all of the six tested abiotic stresses, UV-B, abscisic acid, sucrose, salicylic acid, cold and ethylene, consistent with the promoter region analysis of GbANS. The recombinant protein was successfully expressed in E. coli strain with pET28a vector. The in vitro enzyme activity assay by HPLC indicated that recombinant GbANS protein could catalyze the formation the cyanidin from leucocyanidin and conversion of dihydroquercetin to quercetin, suggesting GbANS is a bifunctional enzyme within the anthocyanidin and flavonol biosynthetic pathway.