Molecular Mechanisms of the Generation and Accumulation of Gas at the Interface.

Gas-evolving reactions are widespread in chemical and energy fields. However, the generated gas will accumulate at the interface, which reduces the rate of gas generation. Understanding the microscopic processes of the generation and accumulation of gas at the interface is crucial for improving the efficiency of gas generation. Here, we develop an algorithm to reproduce the process of catalytic gas generation at the molecular scale based on the all-atom molecular dynamics simulations and obtain the quantitative evolution of the gas generation, which agrees well with the experimental results. In addition, we demonstrate that under an external electric field, the generated gas molecules do not accumulate at the electrode surface, which implies that the electric field can significantly increase the rate of the gas generation. The results suggest that the external electric field changes the structure of the water molecules near the electrode surface, making it difficult for gas molecules to accumulate on the electrode surface. Furthermore, it is found that gas desorption from the electrode surface is an entropy-driven process, and its accumulation at the electrode surface depends mainly on the competition between the entropy and the enthalpy of the water molecules under the influence of the electric field. These results provide deep insight into gas generation and inhibition of gas accumulation.

A Multistep Prediction Model for the Vibration Trends of Hydroelectric Generator Units Based on Variational Mode Decomposition and Stochastic Configuration Networks.

Accurately predicting the changes in turbine vibration trends is a key part of the operational condition maintenance of hydropower units, which is of great significance for improving both the operational condition and operational efficiency of hydropower plants. In this paper, we propose a multistep prediction model for the vibration trend of a hydropower unit. This model is based on the theoretical principles of signal processing and machine learning, incorporating variational mode decomposition (VMD), stochastic configuration networks (SCNs), and the recursive strategy. Firstly, in view of the severe fluctuations of the vibration signal of the unit, this paper decomposes the unit vibration data into intrinsic mode function (IMF) components of different frequencies by VMD, which effectively alleviates the instability of the vibration trend. Secondly, an SCN model is used to predict different IMF components. Then, the predicted values of all the IMF components are superimposed to form the prediction results. Finally, according to the recursive strategy, a multistep prediction model of the HGU's vibration trends is constructed by adding new input variables to the prediction results. This model is applied to the prediction of vibration data from different components of a unit, and the experimental results show that the proposed multistep prediction model can accurately predict the vibration trend of the unit. The proposed multistep prediction model of the vibration trends of hydropower units is of great significance in guiding power plants to adjust their control strategies to reach optimal operating efficiency.

[Overview of quality standards of Eucommiae Cortex in China and overseas].

Eucommiae Cortex is an authentic medicinal material with broad growing areas( such as Hunan and Sichuan provinces in China. It is well-known for its efficacy in tonifying liver and kidney,strengthening muscles and bones,and stabilizing fetus. It has also been proven in pharmacology to possess the functions such as lowering blood pressure and lipids. Hence,Eucommiae Cortex has attracted increasing attention. The current quality standards of Eucommiae Cortex vary in different countries or regions. The quality of Eucommiae Cortex products on the market is affected by mix-ups of non-medicinal parts and insufficient growth years. In view of these problems,this paper summarizes the current quality standards and research progress of Eucommiae Cortex in China and overseas,aiming to provide a reference for the establishment of the quality standards of Eucommiae Cortex.

Development of a sensitive indirect competitive enzyme-linked immunosorbent assay for high-throughput detection and risk assessment of aflatoxin B1 in animal-derived medicines.

Animal-derived medicine is an important part of traditional Chinese medicine (TCM). Studies have shown that many animal-derived medicinal products are susceptible to contaminate of aflatoxins, nevertheless, the rapid detection for animal-derived medicine is prone to be ignored. Here we developed a sensitive indirect competitive enzyme-linked immunosorbent assay (icELISA) for rapid screening of aflatoxin B1 (AFB1) in ground beetle, cockroach, silkworm and earthworm. The sensitivity of the icELISA method was significantly enhanced. The IC50 for the four animal-derived medicinal samples ranged from 0.092 to 0.135 ng mL-1; the limit of detection (LOD) was 0.008-0.020 ng mL-1. To obtain high accuracy, the extraction solution and time were evaluated. By using this method, a total of 138 samples were investigated, and the detection rates of AFB1 in ground beetle and earthworm samples were 26.6% and 16.7%, respectively. The result was validated by liquid chromatography combined with tandem mass spectrometry, and an excellent correlation was observed between the two datasets, with a R2 value of 0.999. Our results indicate that the proposed method can be used for the rapid detection of AFB1 in animal-derived medicine. Furthermore, the quantitative risk assessment was conducted for ground beetle and earthworm based on the results, demonstrating that the intake of AFB1 in ground beetle had a slight threat to the risk of cancer.

Magnetic particles encoding a suspension probe for ultra-sensitive and quantitative determination of atrazine.

As a highly toxic and widely used herbicide, atrazine poses a serious threat to food safety as well as overall environmental and human health. Due to complex matrix interference and the difficulty of signal enrichment, there is an urgent need for a convenient, fast, and ultrasensitive method that detects trace atrazine without concern for matrix effects. Here, we provide the first account of a sensitive and rapid suspension probe based on magnetic microspheres used to detect atrazine in herbs. The self-made magnetic beads featured -COOH groups and were used as the carrier to construct immunofluorescent probes. These probes then conjugated with the atrazine antigen through an activated ester method, ultimately binding to the antibody. Homogeneous detection was ensured using flow cytometry and the microflow optical channel along with allophycocyanin-conjugated goat-anti-mouse secondary antibody (APC-IgG-SecAb) as the fluorescent signal. The magnetic suspension probe allowed for high target enrichment and the inherent two-dimensional selective detection of flow cytometry effectively avoided any matrix interference. This method had good linearity across 1.69-23.19 ng mL-1. The IC50 and LOD values were 4.81 ng mL-1 and 0.95 ng mL-1, respectively; the sensitivity was increased three-fold relative to ELISA. After complete optimization, 2-N-morpholinoeth-anesulfonic acid was used as the coupling solution and maintained good mono-dispersity, stability, and reactivity for the labelled microspheres during the process. The entire experiment was simple, and effectively used reagents; moreover, both the labor required and detection time were greatly reduced. Critically, the strategy presented here greatly reduced interference from complex matrices, and saved preparation for matrix-matched solutions when different herbs were screened. Overall, this strategy was sensitive, rapid, eco-friendly, and labor-saving; collectively, these attributes make it well-suited for on-site screening of atrazine contamination and will allow for increased food safety.

[QuEchERS pretreatment coupled to gas chromatography and tandem mass spectrometry to fast determination of 34 pesticide residues in Glycyrrhizae Radix et Rhizoma].

This study proposed a quantitative method for 34 pesticides including organochlorine,organophosphorus and pyrethroids in Glycyrrhizae Radix et Rhizoma herbs and medicinal slices,and analyzed the pesticide residues of collected Glycyrrhizae Radix et Rhizoma samples from different regions. With acetonitrile extraction and optimized Qu Ech ERS purification,the 32 batches of Glycyrrhizae Radix et Rhizoma herbs and medicinal slices were analyzed by matrix matching standard curve quantitative analysis under GC-MS/MS multi-response monitoring( MRM) mode. This study investigated the pretreatment of Glycyrrhizae Radix et Rhizoma samples based on the Qu Ech ERS method of Chinese Pharmacopoeia( 2015 edition,4),and the result showed that the recoveries of some pesticide was low and pigment has a strong interference in analysis,which result in worse purification effect. Therefore,this paper further optimized the Qu Ech ERS method and corrected the matrix matching standard curve method,and compensated the qualitative and quantitative effects of matrix effects on the detected target compounds in Glycyrrhizae Radix et Rhizoma. The results showed that 34 kinds of pesticide had good linear( R~2 of 0. 996 4 or higher) within a covering 0. 01-0. 2 mg·kg~(-1) concentration range. The limits of quantitation are less than 0. 01 mg·kg~(-1). This method was further applied to the simultaneous determination of 34 pesticide residues of typical organochlorine,organophosphorus and pyrethroids in 32 batches of Glycyrrhizae Radix et Rhizoma herbs and medicinal slices. Six batches containing beta-endosulfan,thiosulphate,o,p'-DDD and thrta-cypermethrin were detected,but none of them exceeded the limit of pesticide residues stipulated in the Chinese Pharmacopoeia and the EU Pharmacopoeia. This study indicates that the established method is rapid,convenient,accurate,and sensitive,which provides a rapid and efficient method for the simultaneous determination of typical organochlorine,organophosphorus and pyrethroids in Glycyrrhizae Radix et Rhizoma.