Search

Objective: A method for the determination of 7 synthetic colorants in freshly prepared beverages by high performance liquid chromatography dual （HPLC） wavelength method with automatic solid phase extraction was established. Methods: Extraction conditions: The sample was extracted 2 times with pure water, and then the supernatant combined after centrifugation. The pH of the supernatant was adjusted to 3~4. After activation by an automatic solid-phase extraction device, loading, rinsing, and elution of the sample were carried out on the Poly-sery synthetic colorant solid-phase extraction column. The eluent was concentrated to 200 μL by nitrogen blowing, and then fixed to 1.0 mL with 50% mobile phase A+50% mobile phase B. Instrument conditions: The column was C18 column. The mobile phase was 20 mmol/L ammonium acetate-methanol, gradient elution. The flow rate was 1.0 mL/min. The injection volume was 10 μL. The detection wavelength were 254 nm and 628 nm. Results: The correlation coefficient of each substance in the range of 0.5～50 μg/mL was greater than 0.999 9, the detection limit of the method was 0.023～0.179 mg/kg, the quantitative limit was 0.078～0.598 mg/kg, the standard recovery was 92.4%～96.8%, and the relative standard deviation （RSD） was 1.2%～4.2%. Conclusion: This method has low consumption of toxic reagents, simple operation steps, high degree of automation, good recovery and repeatability, and it is suitable for the determination of large quantities of samples.

Almond hull, a substantial byproduct comprising more than half of almond fresh weight, has recently gained attention due to its functionality and sustainability benefits. Despite heightened interest, information regarding its toxicity remains limited. In order to assess its genotoxic potential, we conducted Good Laboratory Practice-compliant in vitro and in vivo studies following Organization for Economic Co-operation and Development (OECD) guidelines. No evidence of toxicity or mutagenicity was observed in a bacterial reverse mutation assay using five tester strains, evaluating almond hull at concentrations up to 5 mg/plate, with or without metabolic activation. Almond hull did not induce chromosome structural damage in a chromosome aberration assay using Chinese hamster ovary cells, nor did it cause any spermatogonial chromosomal aberration in tested male BALB/c mice. To evaluate its ability to induce DNA damage in rodents, a combined micronucleus assay was conducted in KM mice of both sexes. Almond hull was administered at doses of 1250, 2500, and 5000 mg/kg/day via gavage once daily for 2 days. No adverse effects of almond hull were observed in the micronucleus assay. Our results indicate no evidence of the genotoxic potential of almond hull administered up to the maximum concentrations of 5 g/kg, as recommended by OECD guidelines. [ABSTRACT FROM AUTHOR]

The gas mixture CO2–O2 has been considered as an insulation and arc-quenching medium in gas-insulated switchgears. In this paper, the dielectric breakdown properties of CO2–O2 mixtures at different O2 concentrations and gas pressures were studied theoretically by considering ion kinetics in a spatial–temporal growth avalanche model. A kinetic scheme that includes all the main reactions likely to occur in CO2–O2 mixtures is presented. An improved method to calculate the dielectric strength of the gas mixture is developed, based on an avalanche model that considers both spatial growth and temporal processes. Next, the reaction rates of ionization, attachment, detachment and ion conversion, the effective ionization Townsend coefficient αeff/N, and reduced critical electric field strength (E/N)cr in CO2–O2 mixtures at different mixing ratios and gas pressures are analyzed in detail. Finally, a pulsed Townsend experiment is performed to verify the validity and accuracy of the calculation method. Based on this, one detachment reaction rate is modified to yield more accurate results. Better consistency between the results and the experimental values supports the validity of the kinetic system, reaction rates, and the improved calculation method. [ABSTRACT FROM AUTHOR]

Recently, C4F7N mixtures have attracted attention as a promising SF6 alternative due to their low global warming potential and excellent electrical performance. In this study, we introduce a newly built experimental setup for pulsed Townsend measurements as well as the physical model for the acquisition of electron swarm parameters. The effective ionization rate coefficients, electron drift velocity, and density-normalized longitudinal diffusion coefficients in C4F7N and its mixtures with CO2 and N2 were obtained. The reduced critical electric field for pure C4F7N at 100 Pa is determined to be 1002 Td, while it decreases with increasing pressure because of the effect of ion kinetics during the discharge process. C4F7N shows good synergism with CO2 and N2. To have a dielectric strength equivalent to that of SF6, the mixing ratio of C4F7N in its mixtures with CO2 and N2 should be 18% and 12%, respectively. The results provide fundamental data for modeling discharges in C4F7N and its mixtures. [ABSTRACT FROM AUTHOR]

Combining magnetic materials with environmentally sensitive polymers to develop intelligent magnetic fluids that respond to external stimuli has become a new research hotspot. At present, the bottlenecks in the development of temperature‐sensitive materials are the complex composition, and its properties in different laboratories vary greatly. Moreover, despite extensive research on magnetic fluids, there remains a dearth of systematic investigation into temperature‐sensitive intelligent magnetic fluids. In this study, we utilized a UV‐visible spectrophotometer to measure the change in transmittance of different magnetic fluid solutions with temperature variation. We systematically investigated the effects of the magnetic fluid dispersion medium, size and concentration of magnetic nanoparticles, type and viscosity of cellulose on the temperature sensitivity of the magnetic fluid. We found that compared with Hydroxypropyl Methyl Cellulose (HPMC) (type I), HPMC (type II) modified magnetic fluid has better stability and a higher phase transition temperature. Moreover, with the increase of the concentration of magnetic fluid, the phase transition temperature is higher. In addition, the lower the viscosity of HPMC‐modified magnetic fluid, the better the stability and the higher the phase transition temperature. We also studied the mechanism of temperature sensitivity, and the results showed that hydrogen bond interactions play an important role. This research will facilitate the use of temperature‐sensitive smart magnetic fluids for biomedical application. [ABSTRACT FROM AUTHOR]

The perfluoronitrile C4F7N is considered a promising SF6-alternative in high-voltage gas-insulated apparatus, thanks to its high dielectric strength and low global warming potential. However, a complete and consistent set of electron-neutral collision cross-sections of C4F7N is still lacking, which hinders relevant plasma modeling. In this contribution, the available electron-neutral collision cross-sections of C4F7N are first compiled and assessed. The initial cross-sections are adjusted iteratively by the electron swarm method to determine a complete and self-consistent cross-section set of C4F7N for the first time. The set is validated by a systematic comparison of electron swarm parameters between Boltzmann equation analysis and experimental measurements in pure C4F7N as well as C4F7N/N2 and C4F7N/Ar mixtures. The proposed cross-section set of C4F7N will be made available to the community in the LXCat database. It will be of particular importance for applications with an emphasis on the discharge mechanisms of this novel gas. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of fruit and vegetable intake on gut microbiota using a mouse model of metabolic syndrome (MS) induced by a high‐fat diet. Forty‐eight male mice were randomly divided into four groups, control group (C), high‐fat diet‐fed model group (H), high fat plus low intake of fruits and vegetables diet‐fed group (H.LFV), high fat plus high intake of fruits and vegetables diet‐fed group (H.HFV), and each group were fed for 60 days. During the experiment, mouse body weights were recorded and fecal samples were collected. Cetyltrimethyl ammonium bromide (CTAB) method was used to extract fecal bacterial DNA, and the purity and concentration of the DNA were detected by electrophoresis. DNA samples underwent PCR amplification (primers in 16 S V4 (515F and 806R)). Raw sequencing data were processed, and sample complexity and multiple‐sample comparisons were investigated. Mouse organ coefficient, serum lipid levels, fecal TC (total cholesterol) and TBA (total bile acid) levels, and hepatic glutathione and malondialdehyde levels were determined. Compared to the H group, the fecal TC and TBA levels decreased significantly in the H.HFV group (p <.05), and hepatic glutathione and malondialdehyde levels decreased significantly in both H.LFV and H.HFV groups (p <.05). Decreased abundance of Firmicutes, Burkholderiales, Syntrophomonas, and Pseudomonadales in gut microbiota was observed in H.LFV and H.HFV groups compared to the H group. The Anosim results showed significant differences in pairwise comparison between groups. The linear discriminant analysis effect size (LEfSe) results showed that k_bacteria not only exhibited statistically differences between H and C groups but also among H.LFV, H.LFV, and H groups, and hence, could be used as a biomarker between groups. To sum up, fruit and vegetable powder could increase the fecal excretion of TC and TBA, and the antioxidant capacity in C57BL/6N mice. Meanwhile, the mechanism that fruit and vegetable powder could prevent MS in C57BL/6N mice was related to the decreased abundance of gut microbiota, including Firmicutes, Syntrophomonadales, and Pseudomonadales. Hence, fruit and vegetable powder could be used as a recommended food to regulate gut microbiota and prevent the occurrence of MS‐related diseases. [ABSTRACT FROM AUTHOR]