Spatiotemporal variations and impact factors of nutrients in the Sanya Bay, northern South China Sea.

Nutrients play a fundamental role in maintaining coastal ecosystem stability. Based on two cruise observations in the winter of 2020 and the summer of 2021, the spatiotemporal variations of dissolved inorganic nitrogen (DIN) and orthophosphate (PO43-) and their influencing factors in Sanya Bay were analyzed. Results show that the mean DIN concentrations in the bay are 2.36 µmol/L in winter and 1.73 µmol/L in summer, and the mean PO43- concentrations are 0.08 µmol/L in winter and 0.04 µmol/L in summer. The nutrient concentrations and composition are significantly affected by the Sanya River. The surface DIN concentrations at the Sanya River estuary are 15.80 and 5.25 times than those inside the bay in winter and summer, respectively. Meanwhile, a high proportion of NO3- (74%) and a low proportion of NH4+ (20%) in DIN appear near the river estuary, while a low proportion of NO3- (37%) and a high proportion of NH4+ (53%) occur away from the estuary. In addition, the thermocline promotes the accumulation of NH4+ at the bottom layer in summer. The high proportion of NO3- is likely not favorable for the survival of coral reefs in eastern bay. Compared with the previous nutrient concentrations, the DIN concentration in the bay has a decrease after 2014, which might benefit from the implementation of the environmental protection policy by government.

An empirical analysis of double reduction education policy based on public psychology.

To effectively reduce the homework burden and off-campus training burden of students in the compulsory education stage in China, China adopts the double reduction policy to carry out corresponding governance in the field of education. This study aims to explore the public's psychological cognition of the current education system under the implementation of the double reduction policy. The public's opinion data on education concepts under the implementation of the double reduction policy are collected, then the SPSS software and Amos software to quantitatively analyze the public's educational concept data are used, and a corresponding structural model equation to analyze the public's opinion on the implementation of the double reduction policy is established. The psychological concepts of all aspects of education are observed, the public's psychological views on education under the implementation of the double reduction policy are finally obtained, the ideological connotation of popularizing the double reduction policy for the general public is provided, and the balanced development of the domestic education system for the implementation of the double reduction policy is ensured. Two suggestions are made in order to provide a corresponding reference for the public's psychological cognition research on the current education system under the implementation of the double reduction policy.

Fetal ECG extraction using short time Fourier transform and generative adversarial networks.

Objective.Fetal ECG (FECG) plays an important role in fetal monitoring. However, the abdominal ECG (AECG) recorded at the maternal abdomen is affected by various noises, making the extraction of FECG a challenging task. The main objective is to present a novel approach to FECG extraction using short time Fourier transform (STFT) and generative adversarial networks (GAN).Methods.Firstly, the AECG signals are transformed from one-dimensional (1D) time domain to two-dimensional (2D) time-frequency domain by using the STFT. Secondly, the 2D-STFT coefficients of FECG are estimated by the GAN model in the time-frequency domain. Finally, after the inverse STFT, the FECG can be reconstructed in the time domain.Main results.Experimental results on two databases demonstrate the effectiveness of the proposed method. Specifically, the SE, PPV andF1of the proposed method on PCDB are 92.37 ± 3.78%, 93.69 ± 3.96% and 93.02 ± 3.81%, respectively. And the SE, PPV andF1on ADFECGDB are 90.32 ± 10.70%, 89.79 ± 9.26% and 90.05 ± 9.81%, respectively.Significance.Unlike the previous studies based on the elimination of maternal ECG in the 1D time domain, the novelty of the proposed method relies on extracting the FECG directly from the AECG in the 2D time-frequency domain. It sheds some light to the topic of FECG extraction.

Qualitative and quantitative assessment of genotoxins using SRRz lysis reporter under the control of a newly designed SOS responsive promoter in Escherichia coli.

A new bacterial genotoxicity detection strain was constructed, in which the cell lysis gene of SRRz from a lambda phage was controlled by a new designed SOS responsive element, designated as Escherichia coli BL21/pUC-PST. The biosensor responded only after 0.5 h contact with mutagens and the changes in cell culture turbidity could be easily differentiated with the naked eyes from the control sample. This SOS/SRRz system presented a dose-dependent manner to five model DNA-damaging agents with an improved detection sensitivity. The limits of detection (LODs) were 0.026 µM for mitomycin C, 320.4 µM for azinphos-methyl, 34.4 µM for methyl methanesulfonate, 4.6 µM for dithianone and 6.0 µM for dichlofluanid, which were much lower than previously reported. By performing binary and ternary mixture experiments, the toxic equivalency concept was validated in the E. coli SOS/SRRz system by comparison with bioanalytical equivalent concentrations (BEQ) and overall toxic equivalent concentration (TEQmixture) using Cr(vi) as the reference compound. Pearson analysis indicated that a strong correlation existed between the TEQmixture and BEQ values. Thus the TEQmixture could be presented as the Cr(vi) equivalent concentration from its dose-effect lysis profiles for the environmental sample. The proposed genotoxicity reporter strain allows for easier qualitative characterization and quantitative interpretation of the TEQmixture values using Cr(vi) as the reference for environmental water samples.

[Prokaryotic expression of HPV 16L1 and optimization of expression conditions].

OBJECTIVE: To construct the HPV16 L1 prokaryotic expression plasmid and to optimize its expression. METHODS: A pair of primers was designed according to plasmid sequences of pGEX-KG and the HPV16L1 genes published by GeneBank. The DNA fragment of 1500 bp was amplified by PCR from the HPV recombinant plasmid with HPV16L1 gene, then cloned into pGEX-KG and transformed into the host E.coli strain JM109. The pGEX-KG-HPV16L1 plasmid was taken and transformed into BL21(DE3) for expression. Induced by IPTG at 37 degree, the expression product of HPV16L1 gene was identified by SDS-PAGE and Western blot. RESULTS: HPV16L1 fusion protein was expressed successfully in the form of inclusion bodies. The molecular weight was 83 kD. Meanwhile, the optimum condition of HPV16L1 fusion protein expression was induced with 1.0 mmol*L(-1) IPTG for 4 h. The fusion protein reacted specifically with antibodies against HPV16L1. CONCLUSION: The prokaryotic expression vector of HPV16L1 gene has been constructed and expressed in E.coli successfully.