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The combination of multifunctional micromagnetic testing and neural network-based prediction models is a promising way of nondestructive and quantitative measurement of steel surface hardness. Current studies mainly focused on improving the prediction accuracy of intelligent models, but the unavoidable and random uncertainties related to instruments were seldom explored. The robustness of the prediction model considering the repeatability of instruments was seldom discussed. In this work, a self-developed multifunctional micromagnetic instrument was employed to perform the repeatability test with Cr12MoV steel. The repeatability of the instrument in measuring multiple magnetic features under both static and dynamic conditions was evaluated. The magnetic features for establishing the prediction model were selected based on the consideration of both the repeatability of the instrument and the ability of magnetic features in surface hardness evaluation. To improve the robustness of the model in surface hardness prediction, a modelling strategy considering the repeatability of the instrument was proposed. Through removing partial magnetic features with higher mean impact values from input nodes, robust evaluation of surface hardness in Cr12MoV steel was realized with the multifunctional micromagnetic instrument.

Magnetic Barkhausen noise (MBN), sensitive to the microstructure of materials, can be applied in the surface decarburization depth detection of ferromagnetic specimens. However, the effects of core microstructures on the determination results of decarburization depth have not been explored. In this study, MBN was employed to evaluate the magnetic properties of the decarburized 60Si2Mn spring steels with martensitic and pearlitic core microstructures. Spring steel samples were austenitized at different times to generate different decarburization depths. Seven magnetic features were extracted from the MBN butterfly profiles. We used the variation coefficient, linear correlation coefficient, and normalized sensitivity to discuss the influence of the core microstructures on these seven features. The different core microstructures led to a large difference in the ability of MBN features to characterize the decarburization layer depth. However, three features of MBN butterfly profiles demonstrated an approximately linear dependency (linear correlation coefficient > 94%) on surface decarburization depth and monotonically increased with the increase in depth in both core microstructures of spring steels.

A novel sensitive vapor generation sampling method, nebulized film dielectric barrier discharge (NFDBD) coupled with inductively coupled plasma mass spectrometry (ICP-MS), was developed in this work for simultaneous determination of noble metals (Rh, Pd, Ir, Pt, and Au). In the presence of formic acid, a 5–11 fold improvement in the sampling efficiency of Rh, Pd, Ir, Pt, and Au by NFDBD was achieved compared with conventional nebulization. Under the optimized conditions, the relative standard deviation (RSD) of Rh, Pd, Ir, Pt, and Au determined at 5 μg L−1 was between 1.4% and 4.3%, and the detection limits (LODs) of Rh, Pd, Ir, Pt, and Au were between 0.1 ng L−1 and 0.7 ng L−1. This NFDBD sampling technique not only operates with no requirement of unstable reagents, easy coupling with flow injection, along with high tolerance for coexisting ions, but also achieves lower LODs than the Na(K)BH4–acid vapor generation system and UV photochemical vapor generation system for noble metal determination. This work also extends the scope of elements that can be determined by DBD plasma vapor generation and provides a highly efficient analytical approach for the determination of Rh, Pd, Ir, Pt, and Au in environmental samples, especially in natural water.

Extracts from plants used in Chinese medicine can be good sources of fungicides for agricultural applications. In this study, we separated and identified antifungal compounds from four traditional Chinese medicine extracts and evaluated their antifungal activities in vitro and in vivo. In vitro, honokiol extracted from Artemisia argyi showed broad-spectrum antimicrobial and mycelial inhibitory activity with EC50 in the range 3.56 − 33.85 μg/mL against eight plant pathogens. q-PCR indicated that honokiol might induce cell cancerisation and inhibit cellular respiration, which provided significant insights into honokiol function in tobacco resistance to molecular mechanisms of the phytopathogenic fungus Phytophthora nicotianae. In vivo, honokiol significantly decreased the rate of fungal infection in eggplants, potatoes, grapes, cherry tomatoes, and cucumbers, and enhanced disease resistance in tobacco. Overall, our results indicate that honokiol has the potential to control a variety of fungal and oomycete diseases, and A. argyi could be a source of honokiol.

The Sr2CaWO6: RE3+ (RE = Dy, Sm and Eu) phosphors with the unusual emissions corresponding to the magnetic-dipole (MD) transition were synthesized via a sol-gel process. The crystal structure, electronic properties, photoluminescence excitation and emission spectra, and fluorescence lifetimes of the as-prepared samples were investigated. X-ray diffraction analysis confirmed that Sr2CaWO6 crystallized in the monoclinic structure with the centrosymmetric monoclinic space group (P21/n). The indirect band gap for Sr2CaWO6 was 4.24 eV, which was calculated within the framework of density functional theory (DFT). The phosphors could be excited by the ultra-violet (UV) light at 280 nm, and exhibited characteristic emissions corresponding to the MD transitions for different RE3+ ions. The WO6 groups in the host lattice can absorb UV light efficiently, and then transferred the energy to activator ions. The results indicated that the doped rare earth ions occupied the centrosymmetric site in Sr2CaWO6 lattice. With increasing the concentration of the dopants, the local symmetry of the activator ions can be effectively changed, which resulted in the enhancement of the characteristic emissions dominated by the electric-dipole (ED) transitions of the doped RE3+. The Sr2CaWO6: Sm3+ phosphor exhibited near white emission under radiation of 280 nm.

The feasibility of 16 types of rare-earth elements (REEs) containing Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu vapor, generated simultaneously, was demonstrated by nebulized film dielectric barrier discharge (NFDBD) in this work. Note that this is the first report on the simultaneous vapor generation of 16 types of REEs, which previously was difficult to realize. Combining it with inductively coupled plasma-mass spectroscopy (ICP-MS) as the sampling technique, a 4-fold to 10-fold improvement in the detection limits (LODs) of the REEs was observed, compared with the conventional solution nebulization, and no obvious interferences from other metal ions and the mutual interferences between REEs at the mg L

Anti-idiotypic nanobodies (AId-Nbs) are novel antigens that can replace the conventional hapten–protein conjugates of small molecule toxins, serving the same function in the competitive immunoassay. Furthermore, nanobodies show increased sensitivity from naive (non immunized) phage display libraries because those obtained have a lower affinity than the binding affinity of the target analytes. Here, we demonstrated a new approach for the development of sensitive and environmentally friendly immuno-PCR (IPCR) for OTA based on phage displayed AId-Nbs against anti-OTA monoclonal antibodies. In this study, a phage displayed AId-Nb was selected from a naive nanobody library. After four cycles of panning, a phage displayed AId-Nb was isolated using a competition-binding biopanning strategy. The half-inhibition concentration (IC50) of the phage-ELISA was 300 pg mL−1, which was 8.83-fold better than that of a conventional ELISA. Furthermore, a non-toxin quantitative IPCR assay was also developed for the detection of ochratoxin A in agri-products based on phage displayed AId-Nbs. The limit of detection (LOD) of the assay is 4.17 pg mL−1, which exhibits a 9-fold improvement over the phage-ELISA. The developed method was successfully validated using OTA contaminated agri-products. Furthermore, novel and environmentally friendly IPCR might have potential applications in a general method for the immunoassay of various toxic small molecules.

Nanobodies that are small and thermally stable, as well as have high expression level, are leading alternative to produce anti-idiotypic antibodies. These antibodies have the advantage of replacing mycotoxins and their conjugates for immunoassays. In this work, anti-fumonisin B1 (FB1) monoclonal antibody (mAb) was used as the target for biopanning from a naive alpaca nanobody (Nb) phage display library. After three cycles of panning, one anti-idiotypic nanobody (Ab2β Nb) was isolated and subjected to a Nb-ELISA for the detection of FB1. Surface plasmon resonance was used to analyze the reaction kinetics between the Ab2β Nb and anti-FB1 mAb. The developed assay showed a half inhibitory concentration (IC50) of 0.95±0.12 ng/mL, a limit of detection of 0.15 ng/mL, a linear range of 0.27-5.92 ng/mL, and a low cross-reactivity toward FB2 of 4.93%. The sensitivity was enhanced approximately 20-fold compared with that of the chemosynthetic FB1-BSA conjugates. The equilibrium dissociation constant (KD) measured for Ab2β Nb: anti-FB1 mAb was 164.6 nM. The assay was compared with conventional ELISA (the commercial ELISA kit), and the results indicated the reliability of Ab2β Nb replacing the antigen-carrier protein conjugates. The use of biotechnology in developing the surrogate is an ideal strategy for replacing conventional synthesized antigens.

A sensitive indirect competitive nanobody-based enzyme linked immunosorbent assay (Nb-ELISA) for ochratoxin A (OTA) with high resistance to cereal matrix interference was developed. Nanobodies against OTA (Nb15, Nb28, Nb32, Nb36) were expressed in E. coli cells and their thermal stabilities were compared with that of an OTA-specific monoclonal antibody 6H8. All nanobodies could still retain their antigen-binding activity after exposure to temperature 95 °C for 5 min or to 90 °C for 75 min. Nb28 that exhibited the highest sensitivity in ELISA was selected for further research. An indirect competitive ELISA based on Nb28 was developed for OTA, with an IC50 of 0.64 ng/mL and a linear range (IC20-IC80) of 0.27–1.47 ng/mL. Cereal samples were analyzed following a 2.5 fold dilution of sample extracts, showing the good resistance to matrix interference of the Nb-ELSIA. The recovery of spiked cereal samples (rice, oats, barley) ranged from 80% to 105% and the Nb-ELISA results of OTA content in naturally contamined samples were in good agreement with those determined by a commercial ELISA kit. The results indicated the reliablity of nanobody as a promising immunoassay reagent for detection of mycotoxins in food matrix and its potential in biosensor development.

Immunoassay is frequently used to analyze mycotoxin contamination. However, the introduction of mycotoxins or their conjugates in conventional immunoassay threatens the safety of individuals and the environment. The variable domain of heavy-chain antibodies (VHHs) can be used as alternative compounds to produce anti-idiotypic antibodies, which work as non-toxic surrogate reagents in immunoassay. In this work, anti-zearalenone (ZEN) monoclonal antibody (mAb) was used as the target for biopanning anti-idiotypic VHH from a naive alpaca VHH phage display library. After four panning cycles, one anti-idiotypic VHH phage clone (Z1) was isolated and the Z1 based phage ELISA for ZEN showed a half inhibitory concentration (IC50) of 0.25±0.02ng/mL, a linear range of 0.11-0.55ng/mL, and a limit of detection (LOD) of 0.08ng/mL. Furthermore, the phage particles of Z1 were also applied to immuno-polymerase chain reaction (PD-IPCR), which supplied both the detection antigens and deoxyribonucleic acid (DNA) templates. Compared with that of phage ELISA, the LOD of Z1 based PD-IPCR was 12-fold improved, with a detection limit of 6.5pg/mL and a linear range of 0.01-100ng/mL. The proposed method was then validated with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results showed the reliability of PD-IPCR for the determination of ZEN in cereal samples. The use of anti-idiotypic VHH phage as non-toxic surrogate and signal-amplification function of PCR make it a promising method for actual ZEN analysis in cereals.