Abstract A method was developed for the simultaneous analysis of pyrethroid, organophosphate, and organochlorine pesticides in fish tissue. Different extraction solvents and solid-phase extraction clean-up procedures were tested. The best approach was to extract by sonication with acetonitrile and 10% methanol, followed by clean-up of extracts using C18, Florisil and Na2SO4 tandem solid-phase extraction cartridges. Gas chromatography with an electron-capture detector was used for analyte determination. All 26 target pesticides were detected using the new method in a single analytical run. The method detection limits ranged from 0.13 to 1.40 µg/kg, while recoveries of the analytes ranged from 86.1 to 133.8% with relative standard deviations ≤12.1% at a spiked concentration of 5 µg/kg. The method was developed to assess possible pesticide contamination in fish collected from lakes at a proposed Illinois National Guard Armory site. Keywords: PyrethroidsOrganochlorine pesticidesOrganophosphate pesticidesTandem solid-phase extractionFish tissue Acknowledgments This research was an interagency agreement with the Department of Military Affairs and the Illinois National Guard. We would like to thank Dr. Jason Belden for his review of the manuscript.
In China, lung cancer remains the cancer with the highest incidence and mortality rate. Among early-stage lung adenocarcinomas (LUAD), the micropapillary (MPP) component is prevalent and typically exhibits high aggressiveness, significantly correlating with early metastasis, lymphatic infiltration, and reduced five-year survival rates. Therefore, the study is to explore the similarities and differences between MPP and non-micropapillary (non-MPP) components in malignant pulmonary nodules characterized by GGOs in early-stage LUAD, identify unique mutational features of the MPP component and analyze the relationship between the ZNF469 gene, a member of the zinc-finger protein family, and the prognosis of early-stage LUAD, as well as its correlation with immune infiltration.
Abstract. \\label{sec:abstract} Snow surface temperature is a key control on energy exchanges at the snow surface, particularly net longwave radiation and turbulent energy fluxes. The snow surface temperature is in turn controlled by the balance between various external fluxes and the conductive heat flux, internal to the snowpack. Because of the strong insulating properties of snow, thermal gradients in snow packs are large and nonlinear, a fact that has led many to advocate multiple layer snowmelt models over single layer models. In an effort to keep snowmelt modeling simple and parsimonious, the Utah Energy Balance (UEB) snowmelt model used only one layer but allowed the snow surface temperature to be different from the snow average temperature by using an equilibrium gradient parameterization based on the surface energy balance. Although this procedure was considered an improvement over the ordinary single layer snowmelt models, it still resulted in discrepancies between modeled and measured snowpack energy contents. In this paper we examine the parameterization of snow surface temperature in single layer snowmelt models from the perspective of heat conduction into a semi-infinite medium. We evaluate the equilibrium gradient approach, the force-restore approach, and a modified force-restore approach. In addition, we evaluate a scheme for representing the penetration of a refreezing front in cold periods following melt. We also introduce a method to adjust effective conductivity to account for the presence of ground near to a shallow snow surface. These parameterizations were tested against data from the Central Sierra Snow Laboratory, CA, Utah State University experimental farm, UT, and Subnivean snow laboratory at Niwot Ridge, CO. These tests compare modeled and measured snow surface temperature, snow energy content, snow water equivalent, and snowmelt outflow. We found that with these refinements the model is able to better represent the snowpack energy balance and internal energy content while still retaining a parsimonious one layer format.
An electrospray condensation nucleation light scattering detector (ESI-CNLSD) was coupled with capillary electrophoresis (CE) for analysis of glyphosate, a chemical of agricultural interest, which is otherwise difficult to detect owing to its lack of chromophores or fluorophores. To reduce the absorption of glyphosate on the CE capillary and to reduce the separation time, an N-cetyltrimethylammonium bromide (CTAB) pre-rinsing CE method was developed here. The protocol consisted of 15 min pre-rinsing of the capillary before analysis with CTAB solution and 5 min with ammonium acetate buffer at pH 2.8. The capillary inner wall coating established by this treatment lasted up to 10 h without bleeding to interfere with CNLSD signal. Calibration data were linear over two orders of magnitude, the instrument detection limit was 0.06 µg/mL and the method detection limit was 0.2 µg/mL. The method was applied to the analysis of local (rural area) lake water and commercial herbicide samples.
Various contaminants in indoor air, dust, and pet hair samples. The distribution of pollutants between media was explained by their sources and partitioning processes. In vitro data helped estimate the risks to human health from indoor exposome.
The reservoir of Erlian oilfield belongs to the small fan—delta deposit system of cliffs, coarse grains and near source. It is in the high-watercut and ultra-high watercut stage in Erlian oilfield: the average recovery rate was only 17.3% and the near wellbore processing cannot resolve the extreme heterogeneity problem in deep reservoir. Field test confirms that the profile controlling and oil displacement technique are effective methods to improve recovery factor in the middle-late period of the reservoir development. The types of the reservoir are low permeability sandstone reservoir, medium permeability and conventional heavy oil sandstone reservoir, conglomerate reservoir and so on. According to the continuity requirements of the profile controlling, oil displacement and microbial injection work, and different requirements of injection parameters in different blocks, different well location and different measures, the system takes the process of alternate dispensing and continuous injection.
A high-performance liquid chromatography-tandem mass spectrometric(HPLC-MS/MS) method was developed to analyze abamectin in sediment.The sample was extracted with a mixture of hexane and acetone by ultrasound-assisted microwave extraction,and purified with solid phase extraction column packed with primary/secondary amine and graphite carbon black.The analytes were separated on a Thermo-C18 column(50 mm×2.1 mm,1.9 μm) using a mixture of acetonitrile ∶ acetic acid-ammonium acetate ∶ water(75 ∶ 10 ∶ 15) as mobile phase.The analysis of the target compounds was performed under atmospheric pressure chemical ionization mode with multiple reaction monitoring.The quantification of abamectin was based on internal standard calibration(emamectin benzoate as the internal standard),and the calibration standards were prepared using matrix-matched solution for compensation of matrix effect.The calibration curve of abamectin was linear in the range of 1.6-400 μg/L with correlation coefficient(r2) of 0.999 3.The relative standard deviations ranged from 2.2% to 16.2%,and the limit of detection was 0.18 ng/g by dry weight.The established method was used to analyze sediment samples collected from an urban stream in Guangzhou,and the results were compared with those obtained by the HPLC/fluorescence detection after derivatization.Similar results were achieved by both methods,but the HPLC-MS/MS method showed greater sensitivity and simplicity,and was suitable for the detection of sediment-associated abamectin at low concentrations.
Chemicals with elevated bioaccumulation profiles present potential hazards to public health and the environment. Ionizable organic compounds (IOCs) increasingly represent a large proportion of commercial chemicals; however, historical approaches for bioaccumulation determinations are mainly developed for neutral chemicals, which were not appropriate for IOCs. Herein, we employed the zebrafish embryo, a common vertebrate model in environmental and biomedical studies, to elucidate toxicokinetics and bioconcentration of eight IOCs with diverse physicochemical properties and pharmacokinetic parameters. At an environmentally relevant pH (7.5), most IOCs exhibited rapid uptake and depuration in zebrafish, suggesting the ionized forms of IOCs are readily bioavailable. Bioconcentration factors (BCF) of these IOCs ranged from 0.0530 to 250 L·kg–1 wet weight. The human pharmacokinetic proportionality factor, apparent volume of distribution (VD), better predicted the BCF of selected IOCs than more commonly used hydrophobicity-based parameters (e.g., pH-dependent octanol–water distribution ratio, Dow). Predictive bioaccumulation models for IOCs were constructed and validated using VD alone or with Dow. Significant relationships between fish BCF and human VD, which is readily available for pharmaceuticals, highlighted the utility of biologically based "read-across" approaches for predicting bioaccumulative potential of IOCs. Our novel findings thus provided an understanding of the partitioning behavior and improved predictive bioconcentration modeling for IOCs.
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