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Pholis fangi is a small, bottom-dwelling fish species endemic to the Yellow Sea and Bohai Sea in China. While previous research has focused on its population biology and molecular structure, little is known about the early developmental stages of this species. In this study, larval and juvenile P. fangi specimens were collected from the Sheyang Sea Area, Jiangsu Province, in 2017. Morphological features were examined using microscopy, and DNA barcoding was conducted to confirm species identification. The research documented detailed changes in yolk sac, fin development, and melanophore distribution patterns across larval and juvenile stages of P. fangi. Comparative analysis with other Pholis species revealed that melanophore distribution is a key distinguishing characteristic, allowing effective differentiation between larval and juvenile stages, as well as between Pholis species. This study provides valuable insights into the early life history of P. fangi, contributing to a better understanding of the genus Pholis. The findings demonstrate the utility of combining traditional morphological observation and molecular techniques for accurate species identification, particularly during the critical larval and juvenile developmental phases. [ABSTRACT FROM AUTHOR]

China has become the major stakeholder in global photovoltaic (PV) technology. However, the existing mechanistic interpretation of "what promotes the technological progress of the Chinese PV industry" is controversial. This paper takes China's A-share listed PV enterprises from 1999 to 2019 as the research sample and uses a panel fixed-effect regression model to empirically test the impact of research and development (R&D) investment and government subsidies on the technological progress of PV enterprises. The results show that there is an "N"-shaped nexus between R&D investment and technological progress, and most PV enterprises are in the climbing stage of the N-shaped curve. With the development of the PV industry, the nexus will undergo a transformation from inverted U-shaped to N-shaped, indicating that R&D investment is a key driver of PV technological progress. Yet, government subsidies are a "double-edged sword". They have a significant positive direct effect on PV technological progress but also a negative moderating effect. Tax returns play a positive incentivizing role, while financial subsidies play a negative moderating role. This study provides a policy basis for the timely reduction of financial subsidies and increased R&D investment to promote technological progress in China's PV industry. [ABSTRACT FROM AUTHOR]

In this study, a magnetic solid-phase extraction (MSPE) method coupled with High-Performance Liquid Chromatography Mass Spectrometry (HPLC–MS/MS) for the determination of illegal basic dyes in food samples was developed and validated. This method was based on Magnetic sulfonated reduced graphene oxide (M-S-RGO), which was sensitive and selective to analytes with structure of multiaromatic rings and negatively charged ions. Several factors affecting MSPE efficiency such as pH and adsorption time were optimized. Under the optimum conditions, the calibration curves exhibited good linearity, ranging from 5 to 60 µg/g with correlation coefficients >0.9950. The limits of detection of 16 basic dyes were in the range of 0.01–0.2 µg/L. The recoveries ranged from 70% to 110% with RSD% < 10%. The results indicate that M-S-RGO is an efficient and selective adsorbent for the extraction and cleanup of basic dyes. Due to the MSPE procedures, matrix effect and interference were eliminated in the analysis of HPLC–MS/MS without the matrix-matched standards. Thus, validation data showed that the proposed MSPE–HPLC–MS/MS method was rapid, efficient, selective, and sensitive for the determination of illegal basic dyes in foods. [ABSTRACT FROM AUTHOR]

In the context of the outbreak of coronavirus disease 2019 (COVID-19), strict lockdown policies were implemented to control nonessential human activities in Xi'an, northwest China, which greatly limited the spread of the pandemic and affected air quality. Compared with pre-lockdown, the air quality index and concentrations of PM2.5, PM10, SO2, and CO during the lockdown reduced, but the reductions were not very significant. NO2 levels exhibited the largest decrease (52%) during lockdown, owing to the remarkable decreased motor vehicle emissions. The highest K+ and lowest Ca2+ concentrations in PM2.5 samples could be attributed to the increase in household biomass fuel consumption in suburbs and rural areas around Xi'an and the decrease in human physical activities in Xi'an (e.g., human travel, vehicle emissions, construction activities), respectively, during the lockdown period. Secondary chemical reactions in the atmosphere increased in the lockdown period, as evidenced by the increased O3 level (increased by 160%) and OC/EC ratios in PM2.5 (increased by 26%), compared with pre-lockdown levels. The results, based on a natural experiment in this study, can be used as a reference for studying the formation and source of air pollution in Xi'an and provide evidence for establishing future long-term air pollution control policies. [ABSTRACT FROM AUTHOR]

With the continuous development of wind power capacity, a large number of wind turbines connected by power electronic devices make the system inertia lower, which leads to the problem of system frequency stability degradation. The virtual synchronous generator (VSG) control can make wind turbines possess inertia and damping. However, the stochastic dynamic behavior of wind generation results in the stochastic changing of operating condition; this paper presents an adaptive subsynchronous oscillation (SSO) damping control method for the wind generation with VSG control. Firstly, the small signal model of the permanent magnet synchronous generator (PMSG) with VSG is built, and the model of state space is derived and built. The active power of PMSG is selected as the variable parameter vector to establish a polytopic linear variable parameter system model. Then, based on the hybrid H2/H∞ control method, each vertex state feedback matrix is solved by linear matrix inequality, and a subsynchronous oscillation adaptive damping controller with polytope is obtained. Finally, the 4-machine 2-area system connected to two PMSGs with VSG control is used as the test system for time domain simulation. The simulation results demonstrate that the LPV based adaptive damping controller could provide enough damping under the circumstances of wider changes of wind power outputs. [ABSTRACT FROM AUTHOR]