Preparation and evaluation of a pyridine sulfonate betaine-based zwitterionic stationary phase for hydrophilic interaction chromatography.

A zwitterionic stationary phase comprising pyridinium cations and sulfonate anions was successfully developed through thiol-ene click chemistry. Using seven polar small molecules as probes, the zwitterionic stationary phase showed high separation selectivity and excellent column efficiency (35,200-54,800 plates/m) compared with two commercial columns. The influence of water proportion, salt concentration, and pH in the mobile phase, and column temperature, on the retention of six polar compounds was examined. The retention mechanism was explored by three hydrophilic retention models, Tanaka test and linear solvation energy relationship analysis. For the analysis of sample dairy products (milk powder, milk, and yogurt), the stationary phase was operated in hydrophilic interaction chromatography mode without the addition of buffer salts, facilitating rapid and efficient detection and quantification of melamine. The LOD and LOQ are 0.04 mg⋅g-1 and 0.13 mg⋅g-1, respectively, and the recovery rate is 90.3 - 102.8 %. The zwitterionic stationary phase has the advantages of simple preparation, good method reproducibility, good selectivity and high precision.

Development of amphiphilic hypercrosslinked porous polymers for magnetic extraction of multiple environmental pollutants in water.

Under the principle of similar compatibility, researchers have developed various polarity extractants corresponding to a class of chemicals. Separating different polarities chemicals with one extractant effectively has become a novel research trend in separation science. Given the complexity of environmental sample matrices and the significant differences in polarity and solubility of various compounds, the introduction of hydrophilic groups to hydrophobic material skeletons can lead to sorbents with hydrophilic-lipophilic balance (HLB) property and thus improve their extraction performance for substances with different polarities. In this work, a hypercrosslinked polymer (HCPPz-TPB), designated as HLB, was synthesized by incorporating polar pyrazine and nonpolar triphenylbenzene molecules within each other. Subsequently, a core-shell magnetic composite material was obtained by encapsulating magnetic Fe3O4 nanoparticles in HCPPz-TPB. The material was applied as an adsorbent for magnetic solid phase extraction (MSPE) and combined with a high-performance liquid chromatography-photodiode array detector (HPLC-PDA) to enrich, separate, and detect seven polar contaminants in environmental water samples. The proposed approach, Fe3O4@SiO2@HCPPz-TPB-MSPE-HPLC-PDA, is characterized by its outstanding high sensitivity, low detection limits, wide linear range, and good reproducibility. The method demonstrated satisfactory linearity in the range of 0.05-2 µg mL-1 with R2 values between 0.9969 and 0.9997; the limits of detection (LOD) were observed to be within the range of 0.0019-0.016 µg L-1, and limits of quantification (LOQ) was observed to be within the range of 0.0064-0.054 µg L-1 range with good precision. The recoveries of the different contaminants in the environmental samples ranged from 83.61 to 116.46% (RSD≤10.56, n = 5). The new hydrophilic-lipophilic balance extractant is highly efficient, sensitive, and precise for extracting different polar pollutants. The findings demonstrate that the Fe3O4@SiO2@HCPPz-TPB display a remarkable affinity for multiple targets, driven by complex interactions including multi-stackings and hydrogen bonding as a sorbent. The synthesized Fe3O4@SiO2@HCPPz-TPB may be employed in diverse applications, including extraction, removal, and determination of diverse trace multi-target analytes in complex media.

Genetic Signature of River Capture Imprinted in Schizopygopsis Fish from the Eastern Tibetan Plateau.

Some East Asian rivers experienced repeated rearrangements due to Indian-Asian Plates' collisions and an uplift of the Tibetan Plateau. For the upper Changjiang (Yangtze/Jinsha River), its ancient south-flowing course and subsequent capture by the middle Changjiang at the First Bend (FB) remained controversial. The DNA of freshwater fishes possess novel evolutionary signals of these tectonic events. In this study, mtDNA Cyt b sequences of endemic Schizopygopsis fish belonging to a highly specialized grade of the Schizothoracinae from the eastern Tibetan Plateau were used to infer the palaeo-drainages connectivity history of the upper Changjiang system. Through phylogenetic reconstruction, a new clade D of Schizopygopsis with three genetic clusters and subclusters (DI, DII, DIIIa, and DIIIb) were identified from the upper Yalong, Changjiang, and Yellow Rivers; the Shuiluo River; the FB-upper Changjiang; and the Litang River; respectively. Ancient drainage connections and capture signals were indicated based on these cladogenesis events and ancestral origin inference: (1) the upper Yalong River likely acted as a dispersal origin of Schizopygopsis fish to the adjacent upper Yellow and Changjiang Rivers at ca. 0.34 Ma; (2) the Litang River seemed to have directly drained into the upper Changjiang/Yangtze/Jinsha River before its capture by the Yalong River at ca. 0.90 Ma; (3) the Shuiluo River likely flowed south along a course parallel to the upper Changjiang before their connection through Hutiao Gorge; (4) a palaeo-lake across the contemporary Shuiluo, Litang, and Yalong Rivers was inferred to have served as an ancestral origin of clade D of Schizopygopsis at 1.56 Ma. Therefore, this study sheds light on disentangling ambiguous palaeo-drainage history through integrating biological and geological evidence.

La Substitution into the Melilite Derivative Ca5Ga6O14: Prediction, Synthesis and Ionic Conductivity.

Melilite-type gallates of general formula RE1+xAE1-xGa3O7+x/2 are of interest for their ability to host mobile interstitial oxide ions in [Ga3O7+x] layers. The crystal structure of Ca5Ga6O14 is closely related to melilite, with [Ga3O7] layers stacked in a more complex way to accommodate an additional 0.5 interlayer cations per formula unit, suggesting the potential for similar oxide ion conduction behavior. We used a computational approach to identify the most promising routes to interstitial oxide incorporation into Ca5Ga6O14, leading to an experimental investigation of the system Ca5-xLaxGa6O14+x/2. Single-phase materials were obtained in the range 0 ≤ x ≤ 0.25 by solid state reactions, producing an ∼40× increase in ionic conductivity at 800 °C. This limited compositional range presents a challenge for characterization of the charge-compensating defects. The La substituents were observed directly by X-ray diffraction and STEM-EDX, and a combination of different structural characterization techniques and DFT calculations indicated the presence of interstitial oxide ions indirectly, explaining the conductivity response. As higher carrier concentrations (x > 0.25) are apparently inaccessible in this system, we conclude that its potential as a useful oxide ion conductor is more limited than that of established melilite materials such as La1+xCa1-xGa3O7+x/2.

PRMT1 promotes radiotherapy resistance in glioma stem cells by inhibiting ferroptosis.

PURPOSE: The existence of glioma stem cells (GSCs) in cancer is related to glioma radiotherapy resistance. In this research, the effect of protein arginine methyltransferase 1 (PRMT1) on the radiosensitivity of glioma stem cell (GSC)-like cells, as well as its underlying mechanism, was investigated. METHODS: GSCs-like cells were analyzed and identified by flow cytometry. The self-renewal capability was evaluated by sphere-forming assay. The PRMT1 expression level in glioblastoma were analyzed using the Gene Expression Profiling Interactive Analysis database. The mRNA and protein were scrutinized by RT-qPCR and western blot, respectively. The radiosensitivity was evaluated by clonogenic survival assay. Ferroptosis was evaluated by detecting the levels of reactive oxygen species, malondialdehyde, Fe2+, glutathione, and 4-hydroxynonenal. RESULTS: U87 and SHG44 cells with GSC-like phenotype (GSC-U87 and GSC-SHG44) displayed strong expression of CD133 and nestin versus the glioma cells. GSC-U87 and GSC-SHG44 possess the self-renewal capability. The level of PRMT1 was higher in glioblastoma tumor tissues than in the normal paracancer tissues. Knockdown of PRMT1 enhanced the radiotherapy sensitivity of GSCs-like cells, which was evidenced by reduced survival fraction in GSC-U87 and GSC-SHG44 underwent sh-PRMT1 transfection. But, this effect was attenuated by Fer-1 (a ferroptosis inhibitor) treatment, accompanied by the abatement of ferroptosis. CONCLUSION: PRMT1 promoted radiotherapy resistance in GSCs-like cells by inhibiting ferroptosis.

[Analysis of phthalate esters from vegetable oils by gas chromatography-mass spectrometry coupled with headspace solid-phase microextraction using cyclodextrin-based hypercrosslinked polymer coated fiber].

Phthalate esters (PAEs) are used as additives to enhance the pliability and malleability of plastics. These substances frequently migrate from packaging materials to vegetable oils because of the absence of covalent bonds. Over time, this migration could result in the accumulation of PAEs in the human body through ingestion, contributing to various diseases. Therefore, accurate qualitative and quantitative analyses of PAEs in vegetable oils are imperative to assess the origins of contamination and investigate their toxicity, degradation, migration, and transformation patterns. However, the concentration of PAEs in most samples is low, and the composition of vegetable oils is complex. Thus, PAEs must be enriched and purified using appropriate sample pretreatment procedures before analysis. Common methods for pretreating PAEs in oil include solid-phase extraction (SPE), dispersive SPE, and magnetic SPE. These techniques require time-consuming and labor-intensive procedures such as oil dissolution, solvent extraction, and degreasing. These approaches also require numerous solvents and containers, increasing the risk of sample cross-contamination. Solid-phase microextraction (SPME) integrates sampling, extraction, purification, concentration, and injection into a single process, significantly accelerating analytical testing and reducing the potential for sample cross-contamination. In headspace (HS) mode, the analytes achieve equilibrium on the coating and are extracted in the gas phase. The fibers are shielded from nonvolatile and high-relative molecular mass substances in the sample matrix. Thus, SPME is an ideal method for extracting volatile compounds in vegetable oils. When HS-SPME coupled with gas chromatography-mass spectrometry (GC-MS), it can achieve the rapid screening of PAEs in vegetable oil. In this study, an SPME with cyclodextrin-based hypercrosslinked polymers (BnCD-HCP) coated on stainless steel fibers was employed to extract PAEs from vegetable oil. The structure and morphology of the polymers were characterized using Fourier-transform infrared spectroscopy, nuclear magnetic spectroscopy, and scanning electron microscopy. BnCD-HCP exhibited high stability and diverse interactions, including π-π, hydrophobic, and host-guest interactions. The oil samples were incubated with methanol, and the PAEs were extracted from the headspace using the probe. The optimal extraction parameters included an extraction time of 20 min, extraction temperature of 50 ℃, desorption time of 4 min, and desorption temperature of 275 ℃. The BnCD-HCP/HS-SPME method was evaluated under optimized experimental conditions. The limits of detection (LODs) and quantification (LOQs) were determined by applying signal-to-noise ratios (S/N) of 3 and 10, respectively. Method accuracy was evaluated using relative standard deviations (RSDs). Single-needle precision was evaluated by conducting three consecutive analyses at 3 h intervals within a day. Inter-needle precision was assessed by conducting the same analyses (three replicates) with differently coated fibers. The 12 PAE compounds exhibited good linearity with correlation coefficients (R2) of at least 0.99. The LODs and LOQs ranged from 0.21 to 3.74 µg/kg and from 0.69 to 12.34 µg/kg, respectively. The RSDs were in the range of 1.8%-11.4% and 5.1%-13.9% for the single-needle and needle-to-needle methods, respectively. The proposed method was applied to soybean, peanut, and sunflower oils, and two PAEs were found in all three oils. Moreover, the method demonstrated good precision (RSD=1.17%-11.73%) and recoveries (72.49%-124.43%). Compared with other methods, the developed method was able to extract many target analytes and had a low or comparable LOD and high recovery. More importantly, this method does not require tedious operations such as solvent extraction and purification. Consequently, the developed method can be used to extract not only PAEs in oils but also other substances with a high lipid content.

Association between body fat distribution and asthma in adults: results from the cross-sectional and bidirectional Mendelian randomization study.

Background: Many studies define obesity based on body mass index (BMI) and explore its relationship with adult asthma. However, BMI only considers height and weight, ignoring other factors such as body fat, which may have a greater impact on health. We investigated the relationship between body fat distribution and adult asthma using both a cross-sectional study and bidirectional Mendelian randomization (MR) analysis. Methods: Weighted logistic regression models were used to examine the relationship between body fat distribution measurements and adult asthma in the cross-sectional study from National Health and Nutrition Examination Survey (NHANES) 2011-2018. Restricted cubic spline (RCS) curves were employed to explore the dose-response relationship between them. The inverse-variance weighted (IVW) method was used as the main method of MR analysis to explore the causal effect of exposure on outcome. Results: After adjusting for all covariates, weighted logistic regression analysis indicated that fat mass in the left arm, left leg, right arm, right leg, trunk, and total body is associated with an increased risk of developing adult asthma (p < 0.05). RCS curves showed that all six fat mass indicators exhibit a J-shaped relationship with adult asthma. Forward MR analysis found a causal effect of six fat mass indicators on the increased risk of adult asthma (p < 0.05). However, reverse MR did not reveal any causal effect of adult asthma on these six fat mass indicators (p > 0.05). Conclusion: Our study supports a positive correlation and a unidirectional causality between body fat distribution measurements and the risk of adult asthma. Further studies are needed to validate our findings.

Nitrogen-Doped Carbon Dots Enhanced Hydrogen Carbonate-Hydrogen Peroxide Chemiluminescent Reaction and its Application in Ascorbic Acid Sensing.

Nitrogen-doped carbon dots (N-CDs) were prepared by self-exothermic procedure using grasshopper powder as a single precursor. The prepared N-CDs not only have excellent fluorescence properties, but also can catalyze and enhance the ultra-weak chemiluminescence of NaHCO3-H2O2. The reaction conditions of NaHCO3-H2O2-N-CDs CL were optimized. Under the optimal experimental conditions, when AA was added to the NaHCO3-H2O2-N-CDs CL system, AA had a significant inhibitory effect on the CL intensity of NaHCO3-H2O2-N-CDs. There was a good linear relationship between the calculated lg(I0/I) and the concentration of AA (C), and the calibration curve equation was lg(I0/I) = 0.03667 C-0.00708 (µM). The established CL analysis method has a detection limit of 0.12 µM for AA and a linear range of 0-50 µM. The selectivity of CL method was evaluated, and the method was successfully applied to the determination of AA in vegetable and fruit samples. The spiked recoveries were between 88.9% and 118.9%, which indicated that the method was simple, rapid, and sensitive, and had great potential in the determination of AA in foods.

Hydrophilic interaction chromatographic evaluation of zwitterionic polymer grafted silica gel via multiple binding sites.

A novel zwitterionic polymer grafted silica stationary phase, Sil-PZIC, was prepared by bonding poly(ethylene maleic anhydride) molecules on the surface of silica via multiple binding sites, followed by ammonolysis of maleic anhydride through a nucleophilic substitution reaction with ethylenediamine. The stationary phase was characterized by solid-state 13C nuclear magnetic resonance, zeta potential, and elemental analysis and the results show the successful encapsulation of zwitterionic polymer on the surface of silica. The chromatographic performance of Sil-PZIC was investigated by using nucleosides and nucleic bases as test analytes The variation of retention and separation performance of these model compounds were investigated by varying the chromatographic conditions such as the components of mobile phase, salt concentration, and pH. The results show that the retention of the Sil-PZIC phase was dominated by a hydrophilic partitioning mechanism accompanied by secondary interactions such as electrostatic and hydrogen bonding. In addition, saccharides and Amadori compounds were also well separated on the Sil-PZIC, indicating that the Sil-PZIC column has potential application for separation of the polar compound.

Fabrication of a magnetic functionalized chitosan hydrogel for effective extraction of aflatoxins from cereals.

A magnetic adsorbent was synthesized by coupling magnetic nanoparticles, UiO-66-NH2 and 1-butyl-trimethylimidazole bromide ([BMIM][Br]) to chitosan (CS)-based composite conveniently. A series of modern characterizations were employed to assess its properties. The results showed that UiO-66-NH2 was uniformly distributed within the composite via in-situ growth, which can enhance the porosity obviously. The introduction of various ligands enables the composite to exhibit excellent extraction performance for four aflatoxins (AFs) through multiple interactions. The adsorption mechanism was elucidated and the main factors affecting extraction efficiency were evaluated. Under optimal conditions, the limits of detection (LODs) ranged from 0.08 to 0.56 µg/kg. The established method was successfully utilized to determine AFs from cereal samples (rice, glutinous rice, wheat, soybean, paddy, and corn) with satisfactory recovery of 77% âˆ¼ 119% with relative standard deviations (RSDs) of 1.0% âˆ¼ 11.7% (n = 5). The adsorbent demonstrated sufficient robustness for repeated use at least six times without obvious damage of extraction property.

Personal, external, and psychological factors influencing adherence to nutrition and diet in patients undergoing metabolic/bariatric surgery: a systematic synthesis of mixed methods research.

AIMS: To offer a holistic view of the personal, external, and psychological factors influencing adherence to nutrition and diet in patients undergoing metabolic/bariatric surgery. METHODS: This systematic synthesis of mixed methods research involved a comprehensive search for articles in English databases, including PubMed, Cochrane Library, Web of Science, EBSCO, Scopus, and Embase, as well as Chinese databases. The search encompassed articles published from the inception of the database up to June 2023. Following the evaluation of literature quality and extraction of relevant information from the selected studies, data from both quantitative and qualitative studies were integrated. The extracted data were analyzed separately, and themes were identified and summarized to elucidate the factors influencing adherence to nutritional and dietary guidelines. The methodology adhered to the guidelines recommended by the Joanna Briggs Institute (JBI) for mixed methods systematic evaluations. RESULTS: Three themes and their corresponding descriptive elements were identified, including: (1) Personal factors: subjective factors (attitude, capability, awareness, behaviors), objective factors (age, sex, work status, economic level, physical activity, dietary habits, weight change); (2) External factors: medication (quantity of pills, complexity of intake times, side effects, unpleasant smell or taste), surgery factor, social influences (family members, dietitians, and peers); (3) Psychological factors: self-efficacy, attachment anxiety, and mental health problems. CONCLUSIONS: The synthesis provided a comprehensive overview of the factors influencing postoperative compliance of nutrition and diet among patients undergoing metabolic and bariatric surgery. It emphasizes the necessity for clinical staff to tailor interventions based on these diverse factors, as well as to attach importance to patients' mental health, giving multidimensional dietary guidance and health care.

Dissolved trace elements in the Ganges-Brahmaputra-Meghna River Basin: A new approach for estimating trace element flux inputs from rivers into the world's oceans.

Understanding the changes in the chemical compositions of dissolved trace elements from source to sink is important for determining their spatiotemporal variations and the contributions from each sub-catchment in the Ganges, Brahmaputra, and Meghna Rivers. To estimate weathering and matter transfer in these Rivers and the Ganges-Brahmaputra-Meghna (G-B-M) Estuary, we measured 15 dissolved trace element concentrations from surface and bottom water samples and exchangeable trace metals from suspended particulate matter (SPM). From December 2019 to January 2020, post-monsoon samples were collected from the upstream of the three rivers and the G-B-M Estuary. Dissolved trace elements in the Ganges and Meghna Rivers exhibited remarkable spatial variations, whereas those in the Brahmaputra River and the G-B-M Estuary were uniform. The dissolved trace elements, basic information (river length and drainage area), and physicochemical parameters (pH, dissolved oxygen, and conductivity) of the three rivers were inconsistent. The sample sites near urban areas and industrial centers had high concentrations of dissolved trace elements. In the G-B-M Estuary, iron and lead concentrations decreased along the salinity gradient, whereas selenium levels gradually increased, which may have been released by the SPM owing to its highly exchangeable trace metals. Compared with historical concentrations, trace elements that entered the G-B Estuary from the Ganges and Brahmaputra Rivers exhibited either decreased or increased metal fluxes due to additional terrigenous sources, suggesting that the inputs of trace element flux from the Ganges and Brahmaputra Rivers into the oceans may need to be re-evaluated. Furthermore, Fe and Pb concentrations and river fluxes in the Ganges and Changjiang have decreased in recent years. Hence, the fluxes of certain trace elements that enter the oceans from large rivers may require re-evaluation.

Ionic liquid-functionalized mesoporous multipod silica for simultaneously effective extraction of aflatoxin B1 and its two precursors from grain.

BACKGROUND: Aflatoxin B1 (AFB1) and its precursors contaminate food and agricultural products, posing a significant risk to food safety and human health, but simultaneous and effective extraction and determination of AFB1 and its precursors with varied structures is still a challenging task. RESULTS: In this study, a bisimidazolium-type ionic liquid functionalized mesoporous multipod silica (SiO2@mPMO-IL(im)2) was fabricated to extract AFB1 and its two precursors, i.e., averantin and sterigmatocystin. The SiO2@mPMO-IL(im)2 could simultaneously extract three targets with varied structures based on the multipods, mesopores, and multifunctional groups. The density functional theory calculations further verified the multiple interactions between SiO2@mPMO-IL(im)2 and targets. The fabricated SiO2@mPMO-IL(im)2 could effectively extract and determine three targets in grains by combing with dispersive solid-phase extraction and high-performance liquid chromatography. Good linearity (r2 > 0.9978), low LODs (0.9-1.5 µg kg-1) and LOQs (3.0-4.5 µg kg-1), satisfactory spiked recoveries (92.5%-106.8%) and high precisions (RSD<6.4%) were observed. SIGNIFICANCE AND NOVELTY: This work demonstrates the feasibility of SiO2@mPMO-IL(im)2 for simultaneous and effective extraction of toxins with varied structures and provides a promising sample preparation for the analysis of AFB1 and its precursors in grain samples.

Anti-Cancer Potency of Copper-Doped Carbon Quantum Dots Against Breast Cancer Progression.

Introduction: The anti-cancer potency of copper-doped carbon quantum dots (Cu-CDs) against breast cancer progression needs more detailed investigations. Methods: With urea and ethylene glycol applied as carbon sources and copper sulfate used as a reactive dopant, Cu-CDs were synthesized in the current study by a one-step hydrothermal synthesis method, followed by the characterization and biocompatibility evaluations of Cu-CDs. Subsequently, the anti-cancer potency of Cu-CDs against breast cancer progression was confirmed by these biochemical, molecular, and transcriptomic assessments, including viability, proliferation, migration, invasion, adhesion, clonogenicity, cell cycle distribution, apoptosis, redox homeostasis, and transcriptomic assays of MDA-MB-231 cells. Results: The biocompatibility of Cu-CDs was confirmed based on the non-significant changes in the pathological and physiological parameters in the Cu-CDs treated mice, as well as the noncytotoxic effect of Cu-CDs on normal cells. Moreover, the Cu-CDs treatments not only decreased the viability, proliferation, migration, invasion, adhesion, and clonogenicity of MDA-MB-231 cells but also induced the redox imbalance, cell cycle arrest, and apoptosis of MDA-MB-231 cells via ameliorating the mitochondrial dysfunctions and regulating the MAPK signaling pathway. Conclusion: Our findings confirmed the biosafety and excellent anti-cancer potency of Cu-CDs against breast cancer progression by tapping into mechanisms that disrupt malignant behaviors and oxidative homeostasis of breast cancer cells.

Construction of MOFs@COFs composite material as stationary phase for efficient separation of diverse organic compounds.

BACKGROUND: The development of efficent chromatographic stationary phases (SP) with mixed-mode or multiple interactions in high-performance liquid chromatography (HPLC) for the separation of complex samples is a challenging task. Metal organic frameworks (MOFs)-based SP can provide desired multiple interactions and enable the separation of a diverse range of solutes, but have limitations of low column efficiency and poor stability. RESULTS: Herein, the hybrid MOFs@Covalent organic frameworks (COFs) materials were used as SP in HPLC due to their synergistic structural features. The SiO2@NH2-UiO-66@CTF SP was synthesized by integration of NH2-UiO-66 and covalent triazine framework (CTF) onto silica surface. Due to the unique structure of SiO2@NH2-UiO-66@CTF with hierarchical-pores, this column showed higher column efficiency (up to 49,369 plates m-1 for alkylbenzenes) than the reported columns packed with MOFs-based SP. Owing to the Zr4+-N coordination bonding between CTF and NH2-UiO-66, the structural stability of SiO2@NH2-UiO-66@CTF can be improved. Furthermore, this new column exhibited remarkable column stability with relative standard deviation of retention time of <0.40% after 400 injections. With the combined advantages of multifunctional properties, high column efficiency, and good stability, SiO2@NH2-UiO-66@CTF SP showed excellent selectivity for the separation of a variety of hydrophobic, aromatic, heteroatomic, and hydrophilic analytes. SIGNIFICANCE AND NOVELTY: This work not only offers a promising SP with multiple retention mechanisms for HPLC, but also provides an efficient strategy for development of high column efficiency MOFs-based SP with good stability. Moreover, the MOFs@COFs hybrid materials were expanded in application area through this study, and the research results can also afford the foundation for further explore its structural characteristics.

A Novel and Highly Efficient Microextraction Method for the Determination of Aflatoxin Precursor Averantin in Fatty Grain Samples.

Averantin (AVN) is an important aflatoxin biosynthetic precursor and has been listed in the screening range of mycotoxins. Herein, a novel ionic liquid-based one-, two-, and three-phase transition microextraction (IL-OTTPTME) method was combined with high-performance liquid chromatography for the extraction and determination of AVN in fatty grain samples. The formation of a homogeneous solution and three-phase system during the IL-OTTPTME process allowed both efficient extraction and coextracted lipid cleanup. Density functional theory calculations and distribution coefficient determination results demonstrated that AVN extraction by IL mainly occurred through hydrogen-bond and π-π interactions. Under optimized conditions, the LOD and LOQ of the proposed method were 0.5 and 1.5 ng/g, respectively. Finally, the method was used to determine AVN in several grains with different fat contents, achieving satisfactory relative recoveries (86.0-107.8%) and RSDs (1.2-6.2%, n = 3).

Scalable Production of Highly Conductive 2D NbSe2 Monolayers with Superior Electromagnetic Interference Shielding Performance.

Thin, flexible, and electrically conductive films are in demand for electromagnetic interference (EMI) shielding. Two-dimensional NbSe2 monolayers have an electrical conductivity comparable to those of metals (106-107 S m-1) but are challenging for high-quality and scalable production. Here, we show that electrochemical exfoliation of flake NbSe2 powder produces monolayers on a large scale (tens of grams), at a high yield (>75%, monolayer), and with a large average lateral size (>20 µm). The as-exfoliated NbSe2 monolayer flakes are easily dispersed in diverse organic solvents and solution-processed into various macroscopic structures (e.g., free-standing films, coatings, patterns, etc.). Thermal annealing of the free-standing NbSe2 films reduces the interlayer distance of restacked NbSe2 from 1.18 to 0.65 nm and consequently enhances the electrical conductivity to 1.16 × 106 S m-1, which is superior to those of MXenes and reduced graphene oxide. The optimized NbSe2 film shows an EMI shielding effectiveness (SE) of 65 dB at a thickness of 5 µm (>110 dB for a 48-µm-thick film), among the highest in materials of similar thicknesses. Moreover, a laminate of two layers of the NbSe2 film (2 µm thick) with an insulating interlayer shows a high SE of 85 dB, surpassing that of the 20-µm-thick NbSe2 film (83 dB). A two-layer theoretical model is proposed, and it agrees with the experimental EMI SE of the laminated NbSe2 films. The ability to produce NbSe2 monolayers on a tens of grams scale will enable their diverse applications beyond EMI shielding.

Simple and rapid ionic liquid-based one-, two-, three-phase transition microextraction for efficient extraction of trace organic pollutants and elimination of lipid co-extractives from fatty food matrices.

Extraction of trace contaminants from fatty food matrices is challenging in food analysis. Herein, a new ionic liquid-based one-, two-, three-phase transition microextraction (IL-OTTPTME) was proposed to efficiently extract trace targets while simultaneously eliminating lipid co-extractives. The method performance was illustrated through the determination of chrysoidine in fatty soybean products using high-performance liquid chromatography-ultraviolet/visible detection. The strong interactions and infinite contact between IL and chrysoidine in the one-phase system ensured ultra-high extraction efficiency (∼100 %). Density functional theoretical calculations confirmed the presence of strong hydrogen bonding and π-π interactions. The formation of the three-phase system during extraction could completely eliminate lipid co-extractives. The IL-OTTPTME integrated extraction, enrichment and cleanup steps into one step, making it rapid and extremely easy to operate. The method had a wide linear range of 0.5-5000 µg/kg and low limit of detection (0.15 µg/kg). It also had satisfactory relative recoveries (95.1 %-104.0 %) and low RSDs (≤5.0 %, n = 5).

Transcriptomics and metabolomics profiling reveals involvement of flavonoids in early nodulation of Caucasian clover (Trifolium ambiguum).

Caucasian clover (Trifolium ambiguum) is a perennial rooted and tillering leguminous forage with strong adaptability, outstanding stress tolerance and other preferable traits. However, the specificity with rhizobia limits the extended application of Caucasian clover. Therefore, it is important to study the changes of genes and metabolites in the early process of nodulation in Caucasian clover to improve its nodulation and nitrogen fixation ability. In this study, we used Caucasian clover as the experimental material to investigate its nodulation mechanism using transcriptomic and metabolomic approaches, such that to break the nitrogen fixation barrier for the promotion of Caucasian clover. Metabolomic and transcriptomic profiling revealed that both DAMs and DEGs were significantly enriched in the phenylpropanoid and flavonoid biosynthetic pathways, with DEGs showing up-regulation at 3 days and 6 days post inoculation (dpi) with rhizobia, and some DEGs showing down-regulation at 9 dpi. Accumulation of flavonoids was significantly increased at both 3 dpi and 6 dpi, and some compounds were significantly decreased at 9 dpi. A total of 35 DEGs were involved in flavonoid synthesis by WGCNA analysis, among which HCT, CCR, COMT and F3H played an important role. This study provides insights in understanding the molecular mechanism of nodulation and nitrogen fixation in Caucasian clover.