Per- and polyfluoroalkyl substances in Chinese surface waters: A review.

The contamination of surface waters in China with Per- and polyfluoroalkyl (PFASs) has been extensively studied in recent decades, however, almost all studies have been conducted in small areas and/or limited samples, which are not representative of the nationwide contamination of surface water environments with PFASs. In this study, attempt was made to provide a comprehensive report about PFASs pollution in Chinese surface water based on the PRISMA. By analyzing 111 papers published between 2006 and 2022, we provide a systematic review of the pollution of PFASs in surface water environments in China. The results show that 26 PFASs contaminants were detected at least once in China's surface water environment and were mainly concentrated in the eastern part of China. Most surface water environments in China had mean PFASs concentrations below 100 ng/L. The most polluted place was the Xiaoqing River, where sampling results in 2020 showed PFASs concentrations as high as 25,429 ng/L, followed by the Tangxun Lake, the Xi River, the Daling River, the Majia River, the Baiyangdian Lake, the Liuxi River, the Jiaolai River, the Tuo River and the Zhimai River. The Xiaoqing River also has the highest concentration of the novel pollutant, with concentrations of HFPO-TA and HFPO-DA as high as 1039 ng/L and 164 ng/L. Based on the source analysis, fluoropolymer manufacturing plants are the main source of PFASs pollutants in surface water. The results of the base risk analysis using risk quotients value (RQ) method show that the RQ values of the Xiaoqing River, the surface water near Bohai Bay, the Majia River and the Tuo River PFOA are 36.9, 7.7, 3.6 and 2.1 respectively, which are high risk areas and require enhanced control. This study provides information on surface waters contaminated by PFASs nationwide, and the results can be used as a reference for the development of pollution control and management strategies for PFASs in surface waters in China.

Synergistic degradation of Tris (2-Chloroethyl) Phosphate (TCEP) by US/Fenton system: Experimental, DFT calculation and toxicity evaluation.

Organophosphorus esters (OPEs), exemplified by tris (2-chloroethyl) phosphate (TCEP), find extensive application in diverse industries such as construction materials, textiles, chemical manufacturing, and electronics, consequently resulting in an increased concentration of these compounds in industrial wastewater. The fundamental objective of this investigation was to examine the degradation of TCEP through the implementation of US/Fenton oxidation techniques in a solution. The findings revealed that the US/Fenton system effectively facilitated the degradation of TCEP, with the Chan kinetic model precisely elucidating the degradation process. Under optimized reaction conditions, the degradation efficiency of TCEP reached an impressive 93.18%. However, the presence of common co-existing aqueous substrates such as Cl-, HCO3-, H2PO4-, and HA hindered the degradation process. Bursting tests and electron paramagnetic resonance (EPR) studies affirmed ∙OH oxidation as the principal mechanism underlying TCEP degradation. Detailed degradation pathways for TCEP were established through the utilization of density-functional theory (DFT) calculations and GC/MS tests. Moreover, the ecotoxicological evaluation of TCEP and its intermediates was conducted using the Toxicity Estimation Software Tool (T.E.S.T.).

Loss calculation and thermal analysis of ultra-high speed permanent magnet motor.

The ultra-high speed permanent magnet motor (UHSPM) for hydrogen fuel cell air compressor is characterized by high speed, high motor power density, small size, and high reliability. Compared to the conventional motor, the loss per unit volume is increased and therefore the calculation of the temperature field is more important than that of conventional motors. In this paper, a UHSPM with a rated speed of 90000 r/min is designed. Firstly, a finite element (FE) model of the UHSPM is established and the losses of each part of the high-speed motor are calculated, and the calculated losses are introduced into the fluid field in the form of a heat source for motor temperature analysis. The calculated losses were introduced into the fluid field in the form of a heat source and used in the motor temperature analysis. The temperature rise was then calculated for the unidirectional and bidirectional magneto-thermal coupling (MTC) respectively. The results show that the bidirectional magneto- thermal coupling (BMTC) simulation results are about 2-3 °C smaller than the experimental measured values, which can more accurately predict the motor temperature. The measurement results verify the accuracy of BMTC, and provide basic theoretical support for the subsequent cooling optimization scheme of high-speed motor.

Detection of Rare Mutations in CtDNA Using Next Generation Sequencing.

The analysis of circulating tumor DNA (ctDNA) using next-generation sequencing (NGS) has become a valuable tool for the development of clinical oncology. However, the application of this method is challenging due to its low sensitivity in analyzing the trace amount of ctDNA in the blood. Furthermore, the method may generate false positive and negative results from this sequencing and subsequent analysis. To improve the feasibility and reliability of ctDNA detection in the clinic, here we present a technique which enriches rare mutations for sequencing, Enrich Rare Mutation Sequencing (ER-Seq). ER-Seq can distinguish a single mutation out of 1 x 107 wild-type nucleotides, which makes it a promising tool to detect extremely low frequency genetic alterations and thus will be very useful in studying disease heterogenicity. By virtue of the unique sequencing adapter's ligation, this method enables an efficient recovery of ctDNA molecules, while at the same time correcting for errors bidirectionally (sense and antisense). Our selection of 1021 kb probes enriches the measurement of target regions that cover over 95% of the tumor-related driver mutations in 12 tumors. This cost-effective and universal method enables a uniquely successful accumulation of genetic data. After efficiently filtering out background error, ER-seq can precisely detect rare mutations. Using a case study, we present a detailed protocol demonstrating probe design, library construction, and target DNA capture methodologies, while also including the data analysis workflow. The process to carry out this method typically takes 1-2 days.

Technical Validation of a Next-Generation Sequencing Assay for Detecting Clinically Relevant Levels of Breast Cancer-Related Single-Nucleotide Variants and Copy Number Variants Using Simulated Cell-Free DNA.

Next-generation sequencing (NGS) is commonly used in a clinical setting for diagnostic and prognostic testing of genetic mutations to select optimal targeted therapies. Herein, we describe the development of a custom NGS assay for detecting single-nucleotide variants (SNVs) and copy number variations (CNVs) in a panel of 51 genes related to breast cancer. We designed and implemented a validation strategy in accordance with principles and guidelines developed by the Next-Generation Sequencing: Standardization of Clinical Testing work group using artificial, cell-free DNA (cfDNA) with mutant fragments prepared in a simple, rapid, and cost-effective manner. For SNV detection, our test had 96.30% sensitivity at mutant allele frequency ≥0.5% with high specificity (99.9997%) and accuracy (99.9996%). For CNV detection, the approach had 95.83% sensitivity for copy numbers at 1.25× (25.6% extra copies) with high specificity (99.77%) and accuracy (99.76%). In addition, our NGS-based assay demonstrated high intrarun and interrun reproducibility, high consistency compared to digital PCR, and a low cross-contamination rate. An overall assessment using cfDNA and plasma cfDNA samples demonstrated our custom NGS assay yields a reliable and robust detection sensitivity with a mutant allele frequency as low as 0.5% for SNVs and copy number of 1.25× for CNVs.