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In this work, a magnetic adsorption material based on metal–organic framework (Fe3O4@ZnAl-LDH@MIL-53(Al)) was synthesized and used as an adsorbent in the process of magnetic solid phase extraction. Then, a high-performance liquid chromatograph was used to quantitatively detect triazole fungicides in samples. In order to verify the successful preparation of the material, a series of characterization analyses were carried out. Besides, the key parameters that may affect the extraction efficiency have been optimized, and under optimal conditions the three triazole fungicides showed good linearity in the range of 10–1000 μg/L (R2 ≥ 0.9796); Limit of detections were ranged from 0.013 to 0.030 μg/mL. Finally, the established method was applied to the detection of triazole fungicides in four fresh juice samples. The results showed that the target analyte was not detected in all the test samples. By detecting the recoveries (73.3–104.3%) and coefficient variation (RSD ≤ 6.8%) of triazole fungicides in fortified samples, it proved that this established method meets the requirements of pesticide residue analysis and showed excellent application potential. [ABSTRACT FROM AUTHOR]

Nitrite reductases play a crucial role in the nitrogen cycle, demonstrating significant potential for applications in the food industry and environmental remediation, particularly for nitrite degradation and detection. In this study, we identified a novel nitrite reductase (AhNiR) from a newly isolated denitrifying bacterium, Acinetobacter haemolyticus YD01. We constructed a heterologous expression system using E. coli BL21/pET28a-AhNir, which exhibited remarkable nitrite reductase enzyme activity of 29 U/mL in the culture broth, substantially higher than that reported for other strains. Structural analysis of AhNiR revealed the presence of [Fe-S] clusters, with molecular docking studies identifying Tyr-282 and Ala-289 as key catalytic sites. The enzymatic properties of AhNiR demonstrated an optimal pH of 7.5 and an optimal catalytic temperature of 30 °C. Its kinetic parameters, Km and vmax, were 1.53 mmol/L and 10.18 mmol/min, respectively, fitting with the Michaelis–Menten equation. This study represents the first report of a nitrite reductase from a denitrifying bacterium, providing a new enzyme source for nitrite degradation applications in the food industry and environmental remediation, as well as for biosensing technologies aimed at nitrite detection. [ABSTRACT FROM AUTHOR]

Since the Harvard Brain Death Criteria was published in 1968, many guidelines and diagnostic procedures of Brain Death/Death by Neurologic Criteria (BD/DNC) have been published throughout the world, and these determination criteria have been constantly revised and updated. The World Brain Death Project published the "Determination of Brain Death/Death by Neurologic Criteria" in 2020 to unify clinical practice across countries and improve the rigorousness of BD/DNC determination. This article analyzes and interprets these "Determination of Brain Death/Death by Neurologic Criteria" (version 2020) to clarify the concept of BD/DNC, the minimum clinical criteria for Determination of BD/DNC, ancillary testing, and the pediatric/neonatal BD/DNC, and to compare with the current practical guidance for determination of brain death in China, and analyze the differences between China and foreign countries, so as to provide reference for medical personnel in related professions in China. doi:10.3969/j.issn.1672⁃6731.2021.04.003

The installation of groynes along the riverbanks is a widely adopted practice in stream corridor restoration projects, aiming to create backflow zones (also known as dead-water zones) that can effectively enhance the river geomorphological diversity.The presence of low-velocity circulation pattern in dead-water zones can promote sediment deposition and nutrient accumulation, thus creating a conductive environment for the growth of aquatic plants. Simultaneously, it can also influence material transport and diffusion processes within rivers, which holds immense importance to river ecosystems.The mean residence time relationship for the dead-water zone with emergent vegetation is investigated here by using a combination of dimensional analysis and genetic algorithm. For vegetated deadwater zones, the factors influencng the mean residence time can be classified into three categories : the hydraulic characteristics of the mixing layer, the morphology features of side-cavities, and the drag effect caused by vegetation. Firstly, the parameter 1 +CDadc, which represents the obstructive impact of vegetation, is introduced via n theorem with reference to previous work. It should be noted that in the absence of vegetation, i.e., 1+CDad,=1, the material exchange activities are not affected by the canopy factor 1+CDad,. However, in the presence of vegetation, the equation 1+CDad.>1 suggests an influence on exchange processes. Secondly, other dominant factors, including the mainstream Froude number Fr which reflects the inlet flow intensity, as well as the three-dimensional shape factor (Wd)a5/L and the width-to-length ratio W/L, which reflect the morphological features of cavities, are identified through a comprehensive analysis and comparison. Then, the aforementioned four factors are used as independent variables to construct a general predictive model for the mean residence time in the vegetated cavity, i.e., a product model of power functions incorporating these four factors. Finally, based on 85 groups of data gathered from previous studies, the genetic program Eureqa is employed to train this general model, and subsequently, a mean residence time relationship is developed for vegetated dead-water zones. The evaluation on the coefficient of determination R and the mean absolute error MAE demonstrates that the present formula possesses good predictive ability, and the analysis of the value ranges of each factor reveals that this formula exhibits a broad range of applicability. In addition, based on a comparative analysis of the impact of the four factors on the model results, the cavity aspect ratio W/L is considered as a critical parameter that significantly influences water residence characteristics in dead-water zones and should be duly taken into account when relevant engineering designs are conducted. [ABSTRACT FROM AUTHOR]