Stable Isotope Tracing Experiments Using LC-MS.

Metabolomics has emerged as a pivotal field in understanding cellular function, particularly in the context of disease. In numerous diseases, including cancer, alterations in metabolism play an essential role in disease progression and drug response. Hence, unraveling the metabolic rewiring is of importance to find novel diagnostic and therapeutic strategies. Isotope tracing is a powerful technique for delving deeper into the metabolic wiring of cells. By tracking an isotopically labeled substrate through biochemical reactions in the cell, this technique provides a dynamic understanding of cellular metabolism. This chapter outlines a robust isotope tracing protocol utilizing high-resolution mass spectrometry coupled to liquid chromatography in cell culture-based models. We cover essential aspects of experimental design and analyses, providing a valuable resource for researchers aiming to employ isotopic tracing.

Quantification of Total Ketone Bodies in Biological Matrices Using Stable Isotope-Labeled Internal Standards and RP-UHPLC-MS/MS.

Acetoacetate (AcAc) and D-beta-hydroxybutyrate (D-ßOHB), the two major ketone bodies found in circulation, are linked to multiple physiological and pathophysiological states. Therefore, analytical methodologies surrounding the quantification of total ketone body (TKB) concentrations in biological matrices are paramount. Traditional methods to quantify TKBs relied on indirect spectrophotometric assays with narrow dynamic ranges, which have been significantly improved upon by modern mass spectrometry (MS)-based approaches. However, the lack of stable isotope-labeled internal standards (ISs) for AcAc and the need to distinguish D-ßOHB from its closely related structural and enantiomeric isomers pose significant obstacles. Here, we provide a protocol to synthesize and quantify a [13C] stable isotope-labeled IS for AcAc, which, in conjunction with a commercially available [2H] stable isotope-labeled IS for ßOHB, allows TKBs to be measured across multiple biological matrices. This rapid (7 min) analysis employs reverse phase ultra-high performance liquid chromatography (RP-UHPLC) coupled to tandem MS (MS/MS) to distinguish ßOHB from three structural isomers using parallel reaction monitoring (PRM), providing excellent specificity and selectivity. Finally, a method is provided that distinguishes D-ßOHB from L-ßOHB using a simple one-step derivatization to produce the corresponding diastereomers, which can be chromatographically resolved using the same rapid RP-UHPLC separation with new PRM transitions. In summary, this method provides a rigorous analytical pipeline for the analysis of TKBs in biological matrices via leveraging two authentic stable isotope-labeled ISs and RP-UHPLC-MS/MS.

Empowering lithium-ion storage: unveiling the superior performance of niobium-based oxide/perovskite heterojunction with built-in electric field.

The increasing demand for high-performance electrode materials in lithium-ion batteries has driven significant attention towards Nb2O5 due to its high working voltage, large theoretical capacity, environmental friendliness, and cost-effectiveness. However, inherent drawbacks such as poor electrical conductivity and sluggish electrochemical reaction kinetics have hindered its lithium storage performance. In this study, we introduced KCa2Nb3O10 into Nb2O5 to form a heterojunction, creating a built-in electric field to enhance the migration and diffusion of Li+, effectively promoting electrochemical reaction kinetics. Under the regulation of the built-in electric field, the charge transfer resistance of the KCa2Nb3O10/Nb2O5 anode decreased by 3.4 times compared to pure Nb2O5, and the Li+ diffusion coefficient improved by two orders of magnitude. Specifically, the KCa2Nb3O10/Nb2O5 anode exhibited a high capacity of 276 mAh g-1 under 1 C, retaining a capacity of 128 mAh g-1 even at 100 C. After 3000 cycles at 25 C, the capacity degradation was only 0.012% per cycle. Through combined theoretical calculations and experimental validation, it was found that the built-in electric field induced by the heterojunction interface contributed to an asymmetric charge distribution, thereby improving the rates of charge and ion migration within the electrode, ultimately enhancing the electrochemical performance of the electrode material. This study provides an effective approach for the rational design of high-performance electrode materials.

Cyano-functionalized porous hyper-crosslinked cationic polymers for efficient preconcentration and detection of phenolic endocrine disruptors in fresh water and fish.

Sensitively analyzing phenolic endocrine-disrupting chemicals (EDCs) in environmental substrates and aquatic organisms provides a significant challenge. Here, we developed a novel porous hyper-crosslinked ionic polymer bearing cyano groups (CN-HIP) as adsorbent for the highly efficient solid phase extraction (SPE) of phenolic EDCs in water and fish. The CN-HIP gave an excellent adsorption capability for targeted EDCs over a wide pH range, and the adsorption capacity was superior to that of several common commercial SPE adsorbents. The coexistence of electrostatic forces, hydrogen bond, and π-π interactions was confirmed as the main adsorption mechanism. A sensitive quantitative method was established by coupling CN-HIP based SPE method with high-performance liquid chromatography for the simultaneously determining trace bisphenol A, bisphenol F, bisphenol B and 4-tert-butylphenol in fresh water and fish. The method afforded lower detection limits (S/N = 3) (at 0.03-0.10 ng mL-1 for water and 0.8-4.0 ng g-1 for fish), high accuracy (the recovery of spiked sample at 88.0%-112 %) and high precision (the relative standard deviation < 8.5 %). This work provides a feasible method for detecting phenolic EDCs, and also opens a new perspective in developing functionalized cationic adsorbent.

Design and fabrication of acorn-like Janus molecularly imprinted materials for highly specific separation and enrichment of oxytetracycline from restaurant oily wastewater.

Molecularly imprinted polymer (MIP) is dedicated to the adsorption of target substances in the aqueous phase, but ignores the adsorption in a more complex environment (oily wastewater). In order to explore the application field of existing MIPs, acorn-like Janus particles were fabricated by photo-initiated seed swelling polymerization. A novel amphiphilic Janus-MIP was prepared with the acorn-like Janus particles as matrix, methacrylic acid, ethylene dimethacrylate and oxytetracycline (OTC) as functional monomers, crosslinking agents and template molecules via surface initiated-atom transfer radical polymerization (SI-ATRP). For comparison, the poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly (GMA-co-EDMA)) microspheres were also utilized as the matrix to prepare common spherical-MIP. The adsorption capacity of Janus-MIP for OTC was 23.8 mg g-1 in oil-water system, while the adsorption capacity of spherical-MIP for OTC was only 12.6 mg g-1 in the same system. At the same time, through high performance liquid chromatography (HPLC) analysis, Janus-MIP can specifically recognize and adsorb trace OTC in restaurant oily wastewater samples, and the proposed method exhibited a lower limit of detection (LOD, 3 ng mL-1) and a higher OTC recovery rate (94.2 %-98.4 %). This work demonstrated great potential for the detection and control of OTC contamination from real samples in an oil-water mixed environment.

Promoting capillary microextraction of six organic nitrogen pesticides in water samples using versatile ZIF-8 hybrid monolithic column.

Because of rapid industrialization and agriculturalization, solving the pressing problems of environment pollution, especially water and food quality, requires innovative solutions. In this paper, a novel and versatile metal-organic framework (ZIF-8)-hybrid monolithic column (ZIF-HMC) was prepared for in-tube solid-phase microextraction (IT-SPME) of organic nitrogen pesticides (ONPs). The prepared monolithic columns had superior adsorption sites, high porosity, excellent permeability, and ideal specific surface area based on Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Thermal Field Emission Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), X-ray Photoelectron Spectroscopy (XPS), and N2 adsorption-desorption. The ZIF-HMC contained a large number of nitrogen and oxygen atoms, benzene rings and ZIF-8, which could synergistically promote the adsorption efficiency of ONPs through multiple interactions, such as hydrogen bonding, π-π accumulation, hydrophobic interactions, cation-π interactions, and pore adsorption by MOFs. Under the optimal conditions, a simple, efficient, and sensitive method for the analysis of six organic pesticides in environmental water samples was developed by using the ZIF-HMC as the extraction medium coupled with high performance liquid chromatography-ultraviolet (HPLC-UV). The method had a wide linear range (0.63-1000 µg L-1), a low detection limit (0.19-1.91 µg L-1) and satisfactory recoveries (87.4 %-110.2 %), the linear correlation coefficient was (R2) 0.9972-0.9995 and the relative standard deviation (RSD) was less than 2.64 %. The study had demonstrated the potential application of the developed method for the enrichment and analysis of organic pesticides in complex matrices of environmental samples, as well as the feasibility of MOFs materials for IT-SPME sample preparation.

Preconcentration of Cinnamic Acid Derivatives in Traditional Chinese Medicines by an Effective Dispersive Liquid-Liquid Microextraction Based on a Hydrophobic Deep Eutectic Solvent.

A dispersive liquid-liquid microextraction based on hydrophobic deep eutectic solvent (hDES) was developed for the extraction and quantification of four cinnamic acid derivatives in traditional Chinese medicines coupled with high-performance liquid chromatography-ultraviolet detection. In this method, a hDES (tetrabutylammonium chloride-hexanoic acid, molar ratio of 1:2) was prepared as the extractant. It only took 15 s to handle multiple samples simultaneously by hand-assisted dispersion. The use of a narrow-bore tube reduced the amount of the hydrophobic extractant with easier recovery. The approach was influenced by several key parameters, including the composition and consumption of the DES, sample phase pH, salt amount, extraction time, and centrifugation time, all of which had been investigated and optimized. Moreover, the formation of the DES was characterized by Fourier-transform infrared spectroscopy and differential scanning calorimetry. Under the optimal conditions, enrichment factors of the target analytes ranged from 135 to 220. Satisfactory linearities (r ≥ 0.9977), detection limits (0.2-0.4 ng/mL), precision (<8.5%), and accuracy (recoveries: 90.0%-104.6%) were obtained. The method has been successfully applied to the simultaneous extraction and preconcentration of four cinnamic acid derivatives in Chinese medicinal samples with rapidness, high efficiency, and convenience.

TFE Terpolymers: Once Promising - Are There Still Perspectives in the 21st Century? Part II: Processing, Properties, Applications.

Tetrafluoroethylene (TFE) terpolymers have emerged as advantageous substitutes for polytetrafluoroethylene (PTFE). Therefore, they are being considered as alternatives to PTFE in many application areas. The advantages of TFE terpolymers include their facile processability at elevated temperatures, their solubility in some polar organic solvents, their inertness against aqueous acids, aqueous bases and a large number of mostly nonpolar organic solvents, their low dielectric constant, their low refractive index as well as useful electro- and thermochemical properties. This review on TFE terpolymers focuses on their processing including shaping and surface modification as well as on selected properties including wettability, dielectric properties, mechanical response behavior, chemical stability, and degradability. Applications including their use as elastomeric sealing material, liner and cladding layer as well as their use as material for membranes, microfluidic devices, photonics, photovoltaics, energy storage, energy harvesting, sensors, and nanothermitic composites will be discussed. The review concludes with a discussion of the future potential of TFE terpolymers and scientific challenges to be addressed by future research on TFE terpolymers.

High-performance adsorption of methylene blue using novel bio-adsorbent based on sargassum fusiforme.

Large specific surface area obtained by pyrolyzed biomass is considered as a vital factor in improving the dye adsorption performance. However, pyrolysis would cause the inevitable destruction of the surface functional groups of biomass. Herein, a biomass adsorbent based on sargassum fusiforme without pyrolysis was employed for the removal of methylene blue (MB). Combining the FTIR, XPS, SEM, and BET analysis, sargassum fusiforme bio-adsorbent (SFBA) was found to have low specific surface area whereas rich functional groups, including carboxyl, carbonyl and hydroxyl groups. SFBA presented high adsorption performance towards MB with a maximum adsorption capacity of 1154.05 mg/g, demonstrating that the high adsorption performance could be achieved by abundant functional groups rather than large specific surface area. In this paper, various adsorption parameters including pH, concentration, contact time, and temperature have also been discussed. The results indicated that the kinetic and isotherm models of SFBA followed the pseudo-secondary kinetic model and the Langmuir isotherm model, respectively. The negative thermodynamic parameters showed that the adsorption process is spontaneous and exothermic. The SFBA enriched with functional groups exhibited high adsorption performance as well as simple fabrication, and abundant sources that could provide a novel alternative for the treatment of dye wastewater.

[Determination of seven phenoxy carboxylic acid herbicides in water using dispersive solid phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry based on metal-organic framework composite aerogel].

Phenoxy carboxylic acid herbicides (PCAs) are difficult to degrade and, thus, pose significant threats to the environment and human health. The limit for 2,4-dichlorophenoxyacetic acid is 30 µg/L in China's standards for drinking water quality, 70 µg/L in the United States' drinking water standards, and 30 µg/L in the World Health Organization's guidelines for drinking water quality. Therefore, the development of an effective detection method for trace PCAs in water is a crucial endeavor. Metal-organic frameworks (MOFs) are novel porous materials that possess advantages such as a large specific surface area, adjustable pore size, and abundant active sites. They exhibit excellent adsorption capability for various compounds. However, the applications of MOFs as adsorbents are limited. For example, the process of isolating powdered MOFs from aqueous solutions is laborious, and microporous MOFs exhibit limited surface affinity, which decreases their mass transfer efficiency in the liquid phase. MOF crystals can be embedded in a substrate to overcome these limitations. Aerogels are obtained by drying hydrogels, which are hydrophilic polymers with a three-dimensional crosslinked network structure. Spongy aerogel materials exhibit unique structural properties such as high porosity, large pore volume, ultralow density, and easy tailorability. When MOFs are combined with an aerogel, their efficient and selective adsorption properties are preserved. In addition, MOF aerogels exhibit a hierarchical porous structure, which enhances the affinity and mass transfer efficiency of the MOF for target molecules. At present, MOF aerogels are primarily prepared by freeze-drying or using supercritical carbon dioxide. These drying processes require significant amounts of energy and time. Hence, the development of greener and more efficient methods to prepare skeleton aerogels is urgently needed. In this study, we prepared an environment-friendly aerogel at ambient temperature and pressure without the use of specialized drying equipment. This ambient-dried MOF composite aerogel was then used for the dispersive solid phase extraction (DSPE) of seven PCAs from environmental water, followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The key parameters affecting the efficiency of DSPE, including the extraction conditions, ratio of MIL-101(Fe)-NH2 to sodium alginate, pH of the aqueous samples, extraction time, ionic strength (salinity), and elution conditions, such as the elution solvent ratio, elution time, and elution volume, were investigated to obtain optimal extraction efficiency. The adsorbent could adsorb the target contaminants within 12 min, and the analytes could be completely desorbed within 30 s by elution with 4 mL of 1.5% (v/v) formic acid in methanol solution. The water samples could be analyzed without pH adjustment. The main adsorption mechanisms were electrostatic interactions and π-π conjugation. Thus, a new method based on MOF aerogels coupled with UHPLC-MS/MS was developed for the determination of the seven PCA residues in water. The calibration curves for the seven PCAs showed good linearity (r2≥0.9986), with limits of detection (LODs) and quantification (LOQs) ranging from 0.30 to 1.52 ng/L and from 1.00 to 5.00 ng/L, respectively. Good intra- and inter-day precision values of 6.5%-17.1% and 7.4%-19.4%, respectively, were achieved under low (8 ng/L), medium (80 ng/L), and high (800 ng/L) spiking levels. The developed method was applied to the detection of PCAs in surface water, seawater, and waste leachate, and the detected mass concentrations ranged from 0.6 to 19.3 ng/L. Spiked recovery experiments were conducted at mass concentrations of 8, 80, and 800 ng/L, and the recoveries ranged from 61.7% to 120.3%. The proposed method demonstrates good sensitivity, precision, and accuracy, and has potential applications in the detection of trace PCAs in environmental water.

[Determination of 42 antimicrobials in disinfection products by dispersive solid phase extraction-high performance liquid chromatography-tandem mass spectrometry].

Antimicrobials inhibit the growth and reproduction of microorganisms thereby alleviating skin and other problems caused by microorganisms. Antimicrobials are classified into different categories, including antibacterials, antifungals, and antivirals, among others, and include azoles, sulfonamides, tetracyclines, quinolones, and many other classes of synthetic and natural compound. The inappropriate or excessive use of antimicrobials can damage skin and other human organs and increase antimicrobial resistance. Relevant regulations and standards clearly state that antimicrobials are prohibited for use as ingredients in disinfection products. However, since antimicrobials enhance the disinfection or antibacterial effect of a product, with a significant short-term effect, antimicrobials are occasionally illegally added to disinfectant products, including those intended for human use. Therefore, establishing testing methods that provide technical support for enforcing regulations is an urgent objective. Herein, a method was established for the analysis of 42 antimicrobials in disinfection products, that is applicable to common types of disinfection-product matrix, including creams, gels, and aqueous solutions, using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) combined with dispersive solid phase extraction. The 42 antimicrobials comprise antibacterials, antifungals, and antivirals, and include seven sulfonamides, ten quinolones, three lincosamides, five tetracyclines, three macrolides, eight azoles, three purine nucleoside analogs, one furan, one nonpolyene antifungal, and one steroid. Briefly, 0.2 g of a sample was first dispersed in 2 mL of water and then extracted with 10 mL of 0.5% formic acid in acetonitrile, with 3 g of anhydrous Na2SO4 added to remove water. After centrifugation, 5 mL of the supernatant was cleaned using dispersive solid phase extraction with EMR-Lipid as the adsorbent. Lipids, waxes, surfactants, and moisturizing lubricants are commonly used as cream and gel matrices. Matrix substances containing long carbon chains dissolved in acetonitrile were removed using the EMR-Lipid adsorbent. Target analytes were separated on a Poroshell 120 EC-C18 analytical chromatography column (150 mm×3.0 mm, 2.7 µm), with 0.1% formic acid in acetonitrile and 0.1% formic acid aqueous solution used as mobile phases under gradient-elution conditions. The target analytes in the test solution were detected in positive ionization (ESI+) and multi-reaction-monitoring (MRM) modes. Analytes were characterized in terms of their retention times and selected ions, and quantified using the external-standard method. The main factors affecting method response, recovery, and sensitivity, such as the extraction method and solvent, purification method and adsorbent, mobile phase, and MS conditions, were examined during sample pretreatment and instrumental analysis. The 42 antimicrobials were effectively separated under the optimized experimental conditions; the target compounds exhibited linear working curves in the 0.25-5.0 mg/kg concentration range, with correlation coefficients (r) greater than 0.99. Limits of detection (LODs) for the 42 antimicrobials were determined from the signal-to-noise ratios (S/N) of their chromatographic peaks. LODs of 0.03-0.10 mg/kg were determined for the three matrices using 0.2-g samples and 10-mL test solution. Recoveries of 80.3-109.8%, with relative standard deviations (RSDs) of less than 9.8%, were obtained by determining three levels of each target analyte added to the three blank matrices; this process was repeated for six parallel samples. The developed method was used to analyze antimicrobials in commercially available disinfection products, with two sample batches testing positive. The established method is simple, accurate, precise, and suitable for the rapid screening and quantification of antimicrobials in disinfection products. This study provides powerful technical support for regulating the illegal addition of related antimicrobials to disinfection products.

[Determination of three methylimidazole compounds in cosmetics by high performance liquid chromatography-tandem mass spectrometry].

Methylimidazole compounds are byproducts formed during the caramel-coloring process and are used in various cosmetics. In addition metronidazole is an antibacterial and anti-inflammatory drug commonly used in modern medicine and is used in cosmetics to treat acne in the short-term. The illegal addition of metronidazole during cosmetics production can result in residual 2-methylimidazole (2-MEI), which, along with 4-methylimidazole (4-MEI), is a class 2B carcinogen. Therefore, establishing efficient, accurate, and sensitive analytical techniques for analyzing methylimidazole compounds in cosmetics is an urgent objective. In this study, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for simultaneously determining 1-methylimidazole (1-MEI), 2-MEI, and 4-MEI in cosmetics was developed. Cosmetics samples were extracted via ultrasonication in acetonitrile and purified using a mixed cation-exchange (MCX) solid-phase extraction (SPE) column, with subsequent drying under a stream of nitrogen and redissolution in acetonitrile. The resulting solution was then filtered through a 0.22 µm organic filter membrane for further testing. The analytes were separated using an XBridge® shield RP18 chromatographic column (150 mm×4.6 mm, 3.5 µm) and isocratically eluted with 20 mmol/L ammonium formate solution (containing 0.1% formic acid)-acetonitrile (98∶2, v/v). The target compounds were ionized by electrospray ionization (ESI) source, analyzed in multi-reaction monitoring (MRM) mode, and quantified using the external standard method, with the peak area of the quantitative ion and the mass concentration of the compound taken as the longitudinal and transverse coordinates, respectively. Matrix-matching working curves were also constructed. 1-MEI exhibited good linear relationships in the range of 5-200 µg/L, with correlation coefficients (r2)≥0.9994, while 2-MEI and 4-MEI showed good linearities in the range of 2-100 µg/L with r2≥0.9984. The three methylimidazole compounds exhibited limits of detection (LODs) and quantification (LOQs) of 10-30 µg/kg and 25-100 µg/kg, respectively. Under three spiked levels (LOQ, 2LOQ, 10LOQ), the recoveries of three methylimidazole compounds were 80.9%-107.9%, with relative standard deviations (RSDs, n=6) of 1.2%-12.8%. The practicability of the method was examined using 48 cosmetic samples; 4-MEI was detected in nine samples at contents of 26-1000 µg/kg, while two samples contained 240 and 267 µg/kg of 2-MEI, respectively. 1-MEI was not detected in any of the 48 samples tested. The developed method is simple, fast, and highly sensitive, and provides methodological support for assessing risks and monitoring the three methylimidazole compounds in cosmetics through screening.

[Comprehensive undergraduate experiment: determination of phenylurea herbicide in tea by magnetic solid-phase extraction-high performance liquid chromatography].

Against the backdrop of the Ministry of Education's promotion of new agricultural science construction and interdisciplinary integration, a comprehensive chemistry experiment to enhance the practical skills of students in preparing biomass functional materials and detecting pesticide residues was designed. Natural loofah was utilized as a precursor in synthesizing nitrogen-doped magnetic porous carbon materials, which were then applied in a magnetic solid-phase extraction (MSPE) technique. Subsequently, high performance liquid chromatography (HPLC) was employed to analyze and detect the phenylurea herbicide monuron in tea. The experimental process included material synthesis, characterization, optimization of the MSPE conditions, adsorption performance studies, and HPLC, reflecting its scientific, systematic nature and providing a comprehensive learning platform for students. It not only deepens student understanding of the relationship between material characterization and application, but also improves their experimental design and problem-solving capacities. Moreover, by integrating cutting-edge science, ideological and political education, and experimental training, it not only stimulates student interest in scientific research and cultivates innovative thinking and practical skills, but also strengthens their feelings of social responsibility and historical mission. This approach realizes the comprehensive educational goals of experimental training and lays the foundation for nurturing high-quality talent with a global perspective and sense of social responsibility.

Greenness and whiteness appraisal for bioanalysis of quetiapine, levodopa and carbidopa in spiked human plasma by high performance thin layer chromatography.

A sustainable HPTLC-densitometric method was developed for quantitative determination of Quetiapine (QUET), Levodopa (LD) and Carbidopa (CD) in presence of Dopamine (DOP) as an internal standard. This applicable technique was achieved by spiking human plasma and extraction was performed using the protein precipitation approach. The mobile phase used was acetone, dichloromethane, n-butanol, glacial acetic acid and water (3: 2.5: 2: 2: 1.75, by volume). Method validation was done according to US-FDA guidelines and was able to quantify Quetiapine, Levodopa and Carbidopa in the ranges of 100-4000, 200-8000 and 30-1300 ng/mL, respectively. Bioanalytical method validation parameters were assessed for the studied drugs. Finally, the analytical suggested methodology was evaluated using various green and white analytical chemistry metrics and other tools, such as the green solvent selection tool, analytical eco-scale, green analytical procedure index, analytical greenness metric approach and the red-green-blue algorithm tool. The results revealed that the applied analytical method had a minor impact on the environment and is a relatively greener option than other previously reported chromatographic methods.

Inducing representational change in the hippocampus through real-time neurofeedback.

When you perceive or remember something, other related things come to mind, affecting how these competing items are subsequently perceived and remembered. Such behavioural consequences are believed to result from changes in the overlap of neural representations of these items, especially in the hippocampus. According to multiple theories, hippocampal overlap should increase (integration) when there is high coactivation between cortical representations. However, prior studies used indirect proxies for coactivation by manipulating stimulus similarity or task demands. Here, we induce coactivation in visual cortex more directly using closed-loop neurofeedback from real-time functional magnetic resonance imaging (fMRI). While viewing one object, participants were rewarded for activating the representation of another object as strongly as possible. Across multiple real-time fMRI sessions, participants succeeded in using this neurofeedback to increase coactivation. Compared with a baseline of untrained objects, this protocol led to memory integration in behaviour and the brain: the trained objects became harder for participants to discriminate behaviourally in a categorical perception task and harder to discriminate neurally from patterns of fMRI activity in their hippocampus as a result of losing unique features. These findings demonstrate that neurofeedback can be used to alter and combine memories.This article is part of the theme issue 'Neurofeedback: new territories and neurocognitive mechanisms of endogenous neuromodulation'.

Comparative Molecular Docking of Apigenin and Luteolin versus Conventional Ligands for TP-53, pRb, APOBEC3H, and HPV-16 E6: Potential Clinical Applications in Preventing Gynecological Malignancies.

This study presents a comparative analysis of molecular docking data, focusing on the binding interactions of the natural compounds apigenin and luteolin with the proteins TP-53, pRb, and APOBEC, in comparison to conventional pharmacological ligands. Advanced bioinformatics techniques were employed to evaluate and contrast binding energies, showing that apigenin and luteolin demonstrate significantly higher affinities for TP-53, pRb, and APOBEC, with binding energies of -6.9 kcal/mol and -6.6 kcal/mol, respectively. These values suggest strong potential for therapeutic intervention against HPV-16. Conventional ligands, by comparison, exhibited lower affinities, with energies ranging from -4.5 to -5.5 kcal/mol. Additionally, protein-protein docking simulations were performed to assess the interaction between HPV-16 E6 oncoprotein and tumor suppressors TP-53 and pRb, which revealed high binding energies around -976.7 kcal/mol, indicative of their complex interaction. A conversion formula was applied to translate these protein-protein interaction energies to a comparable scale for non-protein interactions, further underscoring the superior binding potential of apigenin and luteolin. These findings highlight the therapeutic promise of these natural compounds in preventing HPV-16-induced oncogenesis, warranting further experimental validation for clinical applications.

Ultra-High-Performance Liquid Chromatography-High-Definition Mass Spectrometry-Based Metabolomics to Reveal the Potential Anti-Arthritic Effects of Illicium verum in Cultured Fibroblast-like Synoviocytes Derived from Rheumatoid Arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease. The fruits of Illicium verum, which is a medicinal and edible resource, have been shown to have anti-inflammatory properties. METHODS: In this study, we investigated the effects of I. verum extracts (IVEs) on human RA fibroblasts-like synoviocytes (RA-FLS) by using a sensitive and selective ultra-high-performance liquid chromatography with high-definition mass spectrometry (UPLC-HDMS) method. We subsequently analyzed the metabolites produced after the incubation of cultured RA-FLS with IVEs. RESULTS: IVEs inhibited the proliferation and suppressed the migration of RA-FLS, and reduced the levels of inflammatory factors including TNF-α and IL-6. Twenty differential metabolites responsible for the effects of IVEs were screened and annotated based on the UPLC-HDMS data by using a cell metabolomics approach. DISCUSSION: Our findings suggest that treating RA-FLS with IVEs can regulate lipid and amino acid metabolism, indicating that this extract has the potential to modify the metabolic pathways that cause inflammation in RA. CONCLUSIONS: This might lead to novel therapeutic strategies for managing patients with RA.

Optimization of the Cold Water Extraction Method for High-Value Bioactive Compounds from Chamomile (Matricaria chamomilla L.) Flower Heads Through Chemometrics.

This study focused on optimizing a cold water extraction method to obtain bioactive compounds from chamomile (Matricaria chamomilla L.), addressing increasing consumer demand for natural products and nutraceuticals. A full-factorial design was employed to evaluate the effects of temperature, time, and chamomile amount on the polyphenolic profile of extracts. The samples were characterized by HPLC-DAD and UV-Vis coupled with chemometrics; the analysis showed that extraction time negatively affected extract quality, as did the interaction between time and temperature. In addition, a significant positive quadratic effect for temperature and a positive coefficient for chamomile amount was found. ASCA was used to assess the UV-Vis profile, offering an alternative untargeted method for understanding the variable effects. The optimal extraction conditions (25 °C, 32 min, and 2.5 g of chamomile) produced samples high in hydroxybenzoic and hydroxycinnamic acids and flavanol derivatives. Using A face-centered design, this study also monitored antioxidant activity via a DPPH scavenging assay, confirming that the optimal conditions yielded samples within the range of maximum antioxidant activity in the studied experimental domain.

Experimental Study on the Strength and Durability of Manufactured Sand HPC in the Dalian Bay Undersea Immersed Tube Tunnel and Its Engineering Application.

The usage of manufactured sand concrete is widespread in modern engineering, and it is important to study its performance to improve the overall engineering quality. This paper presents an experimental study on the working performance and durability of 12 groups of manufactured sand high-performance concrete (MSHPC) with varying mix ratios, in the context of the construction of the Dalian Bay undersea immersed tube tunnel. The study reveals that the stone powder content significantly affects the physical and mechanical properties, as well as the durability, of manufactured sand concrete. At an approximately 9% stone powder content, the concrete achieves the highest slump and best workability. However, excessive stone powder reduces early crack resistance. Furthermore, an optimal stone powder content (ranging from 5% to 13%) enhances the compressive strength, with the 28-day compressive strength reaching 60 MPa at a 13% stone powder content, while the effect on the splitting tensile strength is negligible. The stone powder content does not significantly impact impermeability and frost resistance, but at 7-9%, the RCM method shows the lowest chloride ion diffusion coefficient. Additionally, a lower water-binder ratio enhances resistance to chloride ion diffusion. High-performance RCM concrete with a 9% stone powder content was used in the construction of the Dalian Bay Cross-Harbor Tunnel, achieving 28-day and 56-day compressive strengths of C45 and C50, respectively, an impermeability grade of P14, a chloride ion diffusion coefficient of 1.9 × 10-12 m2/s, and a frost durability index of 92%, meeting the project's 100-year lifespan design requirements.

Genetic Study for Identifying Beta Thalassemia Trait in Relatives of Children with Beta Thalassemia Major.

BACKGROUND: The most common inherited illness, thalassemia, is thought to have a detrimental effect on public health, particularly in endemic areas. Children with beta thalassemia disease have several mutations. Prevention and premarital examination are still the most effective measures to lessen the burden of beta thalassemia. OBJECTIVES: This study primarily aimed to determine the beta thalassemia carriers in relatives of beta thalassemia major children, the role of gene study in the confirmation of beta thalassemia trait diagnosis, and to detect the genetic defect in the relatives of beta thalassemia major children. MATERIALS AND METHODS: The cross-sectional study was conducted on 109 healthy children, aged between six months and 18 years, who were the relatives (second and fourth degree) of beta thalassemia major cases. RESULTS: Gene screening, using the amplification refractory mutation system (ARMS) polymerase chain reaction (PCR), covered the most common 22 alleles in the Mediterranean region, and was successful in detecting 61.5% of beta-globin chain mutations of studied participants, in addition to high prevalence (34.8%) of beta thalassemia carriers among the relatives of beta thalassemia children. CONCLUSION: The beta thalassemia carrier rate was found to be highly prevalent among relatives of beta thalassemia major children. Despite the accuracy of gene screening in the detection of beta thalassemia carriers, the use of the most common 22 alleles can only detect 61.5% of carriers; hence, the value of tested gene study is still limited in the detection of carrier rates.