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ObjectiveA method involving derivatization combined with liquid chromatography-tandem mass spectrometry was developed for the determination of vitamin D in infant formula food.MethodsThe samples were treated with enzymolysis， saponification， liquid-liquid extraction， and 4-phenyl-1，2，4-triazoline-3，5-dion derivatization. Chromatographic separation was performed using an Atlantis® T3 column， and gradient elution was performed using the methanol-5 mmol/L ammonium format solution as the mobile phase. The method applied positive electrospray ionization and multiple reaction monitoring mode and was quantified with the isotope internal standard method.ResultsA good linearity was obtained with a correlation coefficient above 0.99. The average recovery levels from three different ranged from 92.3% to 94.2%， and the relative standard deviations were between 3.03% and 5.34% （n=6）. The limit of quantification was 1 μg/kg.ConclusionThis method is simple， accurate with high sensitivity and high selectivity， and suitable for the determination of vitamin D in infant formula food.

Defining the copper-based catalysts that are responsible for the catalytic behaviour of oil-paper insulation systems and implementing effective regulation are of great significance. Accelerated ageing experiments were conducted to reveal variations in copper scales and deterioration in insulation properties. As ageing progressed, TEM images demonstrated that copper species were adsorbed and aggregated on the fibre surface in the form of nanoparticles (NPs). The scale of NPs exhibited a continuous increase, from 27.06 nm to 94.19 nm. Cu(I) and Cu(II) species were identified as the active sites for inducing intense free radical reactions, which significantly reduced the activation energy, making the insulating oil more susceptible to oxidation. The role of the antioxidant di-tert-butyl-p-cresol (DBPC) in extending the insulation life was regulated by determining the optimal addition time based on variations in the interfacial tension. After the second addition of DBPC, the ageing rates of the dissipation factor, acidity, micro-water and breakdown voltage in the Cu+DBPC group decreased by 28.8%, 43.2%, 52.9% and 46.7%, respectively, compared to the Cu group. This finding not only demonstrates the crucial role of DBPC in preventing the copper-based catalyst-induced oxidation of insulating oil, but also furnishes a vital foundation for enhancing the long-term stability of transformer insulation systems. [ABSTRACT FROM AUTHOR]

In the last decade, oil-based titanium dioxide nanofluids (TiO2 NFs) have gained immense interest due to their unique insulating properties and excellent thermal performance, which endow them with the potential for application in the field of modified insulating oils. A timely comparison, analysis and summary of recent advances in the preparation, characterization, and properties of different oil-based TiO2 NFs for oil-immersed power transformers will contribute to provide a useful reference for the subsequent development of such materials. Preparation methods are reviewed along with their merits and demerits. Characterization techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical microscopy (OM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, thermally stimulated current (TSC), pulse electroacoustic technique (PEA), finite element analysis (FEA), fluorescence spectroscopy, Raman spectroscopy and zeta potential analysis are all applied to determine the crystal structure, particle size, surface function, surface charge and stability. Stabilization mechanisms are also discussed in detail. Some critical properties of oil-based TiO2 NFs under the application of different influencing factors such as base oils, crystal structure, size of nanoparticles, surface modifiers, mixing percentage, and aging environment are highlighted. Finally, the existing challenges and perspectives are presented for future research. [ABSTRACT FROM AUTHOR]

The neuromorphic network based on artificial neurons and synapses can solve computational difficulties, and its energy efficiency is incomparable to the traditional von Neumann architecture. As a new type of circuit component, nonvolatile memristors are very similar to biological synapses in structure and function. Only one memristor can simulate the function of a synapse. Therefore, memristors provide a new way to build hardware-based artificial neural networks. To build such an artificial neural network, in addition to the artificial synapses, artificial neurons are also needed to realize the distribution of information and the adjustment of synaptic weights. As the VO2 volatile local active memristor is complementary to nonvolatile memristors, it can be used to simulate the function of neurons. However, determining how to better realize the function of neurons with simple circuits is one of the current key problems to be solved in this field. This paper considers the influence of distribution parameters on circuit performance under the action of high-frequency and high-speed signals. Two Mott VO2 memristor units are connected and coupled with microstrip lines to simulate the Hodgkin–Huxley neuron model. It is found that the proposed memristor neuron based on microstrip lines shows the characteristics of neuron action potential: amplification and threshold. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mango anthracnose is among the most severe diseases impacting mango yields and quality. While this disease can be effectively controlled through chemical means, it is vital that appropriate field efficacy and fate determination studies be conducted when applying pesticides to crops in order to appropriately gauge the ecological and health risks associated with the use of these agents. RESULTS: GAP field trials were conducted to explore the efficacy, dissipation, and terminal residues associated with the application of mefentrifluconazole and pyraclostrobin to mango crops in six locations throughout China. These analyses revealed that three applications of mefentrifluconazole [160 mg active ingredient (a.i.) kg−1] in combination with pyraclostrobin mixture achieved satisfactory disease control efficacy. To simultaneously detect mefentrifluconazole and pyraclostrobin residues on mangoes, a 'quick, easy, cheap, effective, rugged and safe' (QuEChERS) high‐performance liquid chromatography–tandem mass spectrometry (HPLC‐MS/MS)‐based approach was established. The initial mefentrifluconazole and pyraclostrobin concentrations ranged from 0.18 to 0.34 mg kg−1, and these two compounds exhibited respective half‐lives of 5.6 to 10.8 days and 5.5 to 9.0 days. At 21 days following foliage application, the terminal mefentrifluconazole and pyraclostrobin residue concentrations were 0.02–0.04 and 0.01–0.04 mg kg−1, with these concentrations being below the maximum residue limit (MRL) established for pyraclostrobin. Both short‐term [acute reference dose percent (ARfD%) 0.78–2.36% and 2.0–6.08%] and chronic [acceptable daily intake percent (ADI%) 0.08–0.47% and 0.09–0.55%] dietary intake risk assessments for mefentrifluconazole and pyraclostrobin indicated that these terminal residue concentrations are acceptable for the general population. CONCLUSION: Mefentrifluconazole and pyraclostrobin in mango was rapidly degraded following first‐order kinetics models. The dietary risk of mefentrifluconazole and pyraclostrobin through mango was negligible to consumers. The application of a 400 g L−1 mefentrifluconazole–pyraclostrobin suspension concentrate mixture represents a highly efficacious fungicidal approach to controlling mango anthracnose that exhibits significant potential for development as it is easily degraded and associated with low residual concentrations after application. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]