Search

Cardamine libagouensis (Brassicaceae), a new species from Enshi City, Hubei, China, is described and illustrated. The new species is morphologically similar to C. engleriana, but differs by lacking stolons, basal leaves pinnate, sepals 1.0–1.5 mm long, silique 3–4 cm long, and seeds without wings. A preliminary molecular phylogenetic study based on ITS2 sequences suggests that C. libagouensis is closely related to C. engleriana and C. griffithii. [ABSTRACT FROM AUTHOR]

In this study, a novel composite DUT-5/Bi2MoO6 (DUT-5/BMO) photocatalytic material was prepared by two-step hydrothermal method for the first time. The materials were characterized by SEM, XPS, etc. Studies have shown that material with a new n–n heterojunction structure can quickly degrade tetracycline. DUT-5 was embedded between the Bi2MoO6 nanosheets, which promotes the photogenerated electrons from DUT-5 flows to Bi2MoO6, thereby reducing the recombination rate of photo-generated electron–hole pairs. The BET results show that the composite material has a larger specific surface area than the monomer Bi2MoO6. It can provide more active sites. After 60 min of visible light irradiation, the photocatalytic degradation efficiency of TC with 15% DUT-5/BMO reached 84.22%, which is 5.37 and 2.12 times higher than that of pure DUT-5 and Bi2MoO6, ·O2− and h+ were the main active substances in the photocatalysis process. In addition, DUT-5/BMO composites show excellent stability and recyclability in 5 times cyclic experiments. In conclusion, DUT-5/BMO has good stability in the environment, and can be used for environmental remediation without pollution. [ABSTRACT FROM AUTHOR]

The crucial oxidant in photocatalytic degradation of dye is the photogenerated reactive oxygen species (ROS) but many photocatalytic processes suffer from low ROS generation efficiency. In this paper, 1T-MoS2 quantum dot modified flower-like BiOBr nanocomposites were synthesized to forming a Type-II heterojunction. As-prepared 1T-MoS2@BiOB composites showing excellent activity for degradation of rhodamine B (RhB) under visible light, BiOBr loaded with 0.2wt% 1T-MoS2 quantum dots has achieved 96.9% efficiency within 18 min. Such outstanding photocatalytic activity is attributed to the flower-like structure and heterojunction between 1 T-MoS2 and BiOBr which provide a fast transfer pathway for excitons and promote the activation of molecular oxygen. In addition, a possible catalytic mechanism was proposed. This work will provide new insight for design and fabrication of cheaper and more effective photocatalysts for molecular oxygen activation in environmental remediation. [ABSTRACT FROM AUTHOR]

Aiming at the complicated operation, time-consuming, incomplete hydrolysis and unstable hydrolysis products of enzymatic hydrolysis, we have established a microwave hydrolysis-liquid chromatography-atomic fluorescence spectrometry method for the determination of selenoamino acids in selenoproteins. After microwave hydrolysis with HC1(6 mol/L),the sample was adjusted to pH value of 7.5, then the selenocystine (SeCys2), Se-methylselenocysteine (MeSeCys) and selenomethionine (SeMet) were separated by anion chromatography with pH = 6.0,40 mmol/L (NH4)2HPO4 solution as mobile phase, flow rate at 0.7 mL/min and isocratic elution for 12 min, and the corresponding concentration were detected with an atomic florescence spectrometer. The microwave hydrolysis conditions are optimized by star point design-response surface method. The optimal hydrolysis conditions are as follows: weighing 20 mg, hydrolysis temperature 150 °C, hydrolysis time 40 min. The SeCys2, MeSeCys and SeMet showed a linear relationship in the concentration range of 0-100 ng, the correlation coefficients were all greater than 0.999, the detection limit was 0.07, 0.03 and 0.14 mg/kg, respectively, and the RSD was 5.6%, 4.6%, 3.7% (n= 6), respectively. It has the advantages of short time-consuming, low cost, complete hydrolysis, simple operation and stable hydrolysate. It can scientifically evaluate the composition of selenoamino acids in selenoproteins, and provides a scientific method for the quality control and traceability of selenoprotein products. The method is worthy of promotion and application. [ABSTRACT FROM AUTHOR]

The Chinese sucker (Myxocyprinus asiaticus) is an endangered and threatened fish species in China. To augment wild populations, millions of captive‐bred Chinese sucker have been released into the upper Yangtze River in recent years, with little evaluation of the genetic impact.The genetic diversity of 112 wild M. asiaticus from different reaches of the Yangtze River was examined, and the population structure among them and three artificially bred populations was determined using 12 microsatellite markers. Genetic data from the wild M. asiaticus populations before the hatchery release programme were synthesized and compared to detect fine‐scale variation in genetic structure together with spatiotemporal changes in the wild population.The results showed that the genetic diversity of wild M. asiaticus was relatively high (observed heterozygosity = 0.604–0.609, polymorphic information content = 0.442–0.496), even though a moderate decrease in total diversity was detected when compared with previous studies. M. asiaticus from the Wanzhou reaches, which showed low genetic variation before the stocking programmes, displayed the highest level of genetic diversity (observed heterozygosity = 0.609, polymorphic information content = 0.496) in this study. Insignificant differences in genetic structure among wild populations, with low genetic differentiation (Fst = 0.035–0.083), as well as close genetic relationships between wild and hatchery populations were observed.Current genetic diversity and population structure of wild M. asiaticus were strikingly different from those before the hatchery release programme, which indicated that stocking activities have altered the genetic character of the populations in the upper Yangtze River. The conservation of M. asiaticus requires legal protection for the fish and its habitat. Genetic monitoring of the wild populations and accurate evaluation of genetic divergence is imperative. In addition, the results of this study should be used to provide scientific guidance for an effective hatchery release programme for M. asiaticus. [ABSTRACT FROM AUTHOR]

The advent of machine learning (ML) has significantly advanced enzyme engineering, particularly through zero‐shot (ZS) predictors that forecast the effects of amino acid mutations on enzyme properties without requiring additional labeled data for the target enzyme. This review comprehensively summarizes ZS predictors developed over the past decade, categorizing them into predictors for enzyme kinetic parameters, stability, solubility/aggregation, and fitness. It details the algorithms used, encompassing traditional ML approaches and deep learning models, emphasizing their predictive performance. Practical applications of ZS predictors in engineering specific enzymes are discussed. Despite notable advancements, challenges persist, including limited training data for ZS predictors and the necessity to incorporate environmental factors (e.g., pH, temperature) and enzyme dynamics into these models. Future directions are proposed to advance ZS prediction‐guided enzyme engineering, thereby enhancing the practical utility of these predictors. [ABSTRACT FROM AUTHOR]

An accurate analytical electrothermal drain current (Ids) model for AlGaN/GaN HEMTs is presented in this letter. The model is implemented into our recently proposed quasi‐physical zone division (QPZD) model for demonstration purpose. Compared with the original QPZD model, its electrothermal characteristics are enhanced by involving more fundamental temperature dependent elements. In addition, these elements are derived analytically based on physical mechanisms instead of former pure empirical fitting method. Thus, the extracted parameter values are more close to intrinsic values. An in house 0.15‐μm GaN HEMT is used for validation. Compared with the measured data at a wide ambient temperature range (245‐390 K), this electrothermal model demonstrates good accuracy to predict the DC characteristics and RF performances of GaN HEMTs. [ABSTRACT FROM AUTHOR]

This paper presents the temperature dependence of small signal performance of GaN‐on‐diamond high electron mobility transistors (HEMTs) at an ambient temperature range from 0°C to 125°C. The temperature influence on the parasitic resistances together with the intrinsic parameters is investigated, and the temperature coefficients of these parameters are extracted from measured data. For comparison, a GaN‐on‐SiC device is also investigated. These results are important for the development and application of the GaN‐on‐diamond HEMT technology. [ABSTRACT FROM AUTHOR]

In this paper, a reliable and efficient parameter extraction method for GaN high electron mobility transistor (HEMT) small‐signal models has been proposed. By utilizing parameter scanning method, the initial values of the extrinsic elements are first extracted from the cold pinch‐off and cold unbiased measurement conditions, respectively. An iterative optimization algorithm is employed then to optimize the extrinsic elements. This scanning and iteration combined algorithm based on a direct extraction method of extrinsic elements can reduce the impact of the approximation error, which makes the determined values of the small‐signal parameters more reliable. The extraction flow has been realized in a Matlab program for efficiency. A 16‐element small‐signal equivalent circuit model (SSECM) for GaN HEMTs has been employed, and the new parameter extraction method has been validated by comparing the simulated small‐signal S‐parameters with the measured data from 0.1 GHz to 40 GHz for two different device dimensions. [ABSTRACT FROM AUTHOR]