Search Results (6,329)

In this work, samples of reduced graphene oxide (rGO) were prepared by treating graphite oxide (GrO) with thiourea (TU) and ascorbic acid (AA). Aerogels rGO-TU and rGO-AA were prepared using the freeze-drying method and were analyzed using X-ray diffraction, FTIR and Raman spectroscopy, ¹H and ¹³C NMR, TEM, and SEM-EDS. Based on the NMR, FTIR, SEM-EDS, and TEM data, GO with TU is reduced with simultaneous functionalization of its oxygen-containing groups. According to ¹H and ¹³C NMR data, the reduction of GO occurred simultaneously with an interaction of the amino groups of thiourea with carbonyl groups on the graphene sheets, forming an imine bond. This is evidenced by the appearance of additional signals in the ¹³C spectrum of GO-TU samples in the region of 140–230 ppm. The Boehm titration method showed that the number of oxygen-containing groups in rGO-TU aerogels decreased by about five times compared to GO. However, thiourea interacts with the GO surface, most likely due to electrostatic interaction and hydrogen bonds. The adsorption capacity of rGO-TU aerogel with respect to methylene blue (MB) after 1440 min was 60.2 mg/g, while for rGO-AA it was 71.4 mg/g. This fact indicates the importance of optimizing GO reduction to increase the number of active sites. Full article

Objectives: This study aimed to analyze metabolites changes in elite freestyle wrestlers during three specific training phases—pre-training, peak training, and recovery adjustment—through serum metabolomics analyses and biochemical indicator testing, providing preliminary insights for selecting effective functional assessment metrics. Methods: Five male wrestlers (20.40 ± 2.07 years) and five female wrestlers (19.60 ± 0.55 years) were enrolled. Morning fasting venous blood samples were collected before training, at peak training intensity, and after training adjustment and recovery. Serum metabolomic analyses using ¹H nuclear magnetic resonance (¹H NMR) spectroscopy and assessment of biochemical indicators were performed. Results: The metabolomic analysis identified six significantly altered serum biomarkers in male wrestlers and three in females across different training phases. These differential metabolites are primarily implicated in the regulation of energy and amino acid metabolism pathways. Additionally, significant alterations in conventional biochemical indices were observed. Conclusions: Metabolomic markers provide a more accurate and comprehensive reflection of metabolic characteristics in freestyle wrestlers, offering a promising complementary approach to traditional biochemical assessments for monitoring physiological states. Full article

Interactions of ZnO nanoplates with water are crucial in determining its structure and performance of the catalyst, yet the details for these processes remain missing due to the lack of an effective detection method that provides resolution at the atomic level. Here, ¹⁷O solid-state NMR spectroscopy is applied to investigate the interactions and the associated stabilization mechanisms for the polar surface of ZnO nanoplates. It shows that the specific O sites (around Zn vacancy) on the polar surface also contribute to the ¹⁷O NMR signal at −18.8 ppm. The observed trends in both ¹⁷O and ¹H spectra after exposing to water vapor further support the assignment of this ¹⁷O high-frequency signal (−18.8 ppm). In addition, the dissociation of water at defective sites of polar surfaces is evidenced, which leads to the generation of OH groups on both (000$\overline{1}$)-O and (0001)-Zn surfaces. The generated OH species obviously improves the dispersity of ZnO nanocrystals, as well as the stability of polar facets by significant electrostatic repulsion interactions. This study will provide insight into the adsorption properties of water on polar facets and the related stabilization mechanisms of the polar surface in nanocrystals. Full article

Reactions of anhydrous Zn(II) iodides with redox-active 1,4-diaza-1,3-butadiene (DAD) and its bis(imino)acenaphtene (BIAN) derivatives in absolute acetonitrile yielded a series of new complexes: [(Mes-DAD)ZnI₂] (1), [(dpp-DAD)ZnI₂] (2), and [(dpp-BIAN)ZnI₂] (3). Single crystals of all compounds were obtained, and their molecular structures were unambiguously determined by X-ray diffraction analysis. Purity of bulk samples in solid state was confirmed by PXRD. Stability of the complexes in solution was investigated by means of UV-Vis and NMR spectroscopy. Cyclic voltammetry revealed two or three quasi-reversible reduction waves in the cathodic region for complexes 1–3. The ability of 3 to accept up to three electrons highlights the potential of these compounds as electrocatalysts for reductive transformations. Full article

Background/Objectives: Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by sustained inflammation, leading to diabetic kidney disease (DKD). This study investigated urinary tubular injury biomarkers and metabolomic profiles in relation to albuminuria and renal function across varying durations of T1D. Methods: A cross-sectional analysis was conducted in 247 youth-onset T1D patients categorized by disease duration: short ≤ 5 years (T1D-S, n = 62), medium 6–10 years (T1D-M, n = 67), and long > 10 years (T1D-L, n = 118). Urinary cytokines (MCP-1, KIM-1, NGAL) were measured by ELISA. Metabolomic profiling was performed using ¹H-NMR spectroscopy. Results: Urinary MCP-1/Cr, KIM-1/Cr, and NGAL/Cr levels were significantly elevated in T1D patients compared with non-diabetic controls, but did not correlate with disease duration. Metabolomic profiling identified distinct urinary signatures across T1D duration. Specifically, N-acetylcysteine (NAC) and N-delta-acetylornithine (NAO) increased progressively, while N-acetylaspartate (NAA) and pyruvic acid decreased with longer disease duration. These four metabolites remained statistically significant after both based on Mann–Whitney tests with false discovery rate (FDR) correction (q < 0.05) and application of a conservative alpha threshold (p < 0.01), suggesting potential disruptions in amino acid and carbohydrate metabolism. Conclusions: Urinary biomarkers (MCP-1/Cr, NGAL/Cr, and KIM-1/Cr) are sensitive indicators of subclinical kidney dysfunction in T1D patients, often preceding albuminuria. Alterations in amino acid-related metabolites (NAC, NAA, and NAO) and pyruvate highlight possible metabolic disturbances associated with T1D duration and oxidative stress. However, given the cross-sectional design, longitudinal studies are needed to confirm causality and clarify their predictive value in DKD progression. Full article

Transition metal complexes bearing protic N-heterocyclic carbene (pNHC) ligands are promising precatalysts for organic reactions due to their capacity for unique hydrogen-bonding interactions. Herein, we report the synthesis and structural characterization of the first Pd(II) complex featuring a pNHC derived from 1,2,4-triazole—a heterocyclic system previously unexplored for the preparation of metal/pNHC complexes. The complex was synthesized via oxidative addition of 3-bromo-5-cyclohexyl-1-methyl-1H-1,2,4-triazole to Pd(PPh₃)₄ in the presence of NH₄BF₄. Its molecular structure was characterized by NMR spectroscopy and X-ray diffraction analysis. Full article

We report the synthesis, spectroscopic, structural, and ultrafast photophysical investigation of a series of homoleptic and heteroleptic Zn(II) complexes based on the donor-acceptor β-diketonate ligand 4,4,4-trifluoro-1-phenylbutane-1,3-dione. Mass spectrometry, infrared, and NMR analyses confirm complexation and indicate possible fragmentation pathways involving the sequential loss of β-diketonate ligands. Single-crystal X-ray diffraction revealed that all complexes adopt monomeric octahedral geometries, with the ancillary nitrogen-based ligands introducing variable distortions. Thermal analyses confirmed that the complexes are non-volatile and have an onset >250 °C, with thermal decomposition primarily to ZnO and ZnF₂. Complexes with aromatic Lewis base led to higher residue percentages, likely due to the final graphitic carbon content. UV-Vis absorption and femtosecond transient absorption spectroscopy demonstrate that the chelated β-diketonate ring serves as the main optically active chromophore, a property unaffected by the nitrogen ligands. The free ligand undergoes rapid internal conversion, whereas coordination to Zn stabilizes the triplet state via LMCT, producing long-lived and chemically reactive species relevant to dissociation processes. This study demonstrates how tailored ligand environments can be exploited to tune excited-state properties, offering a rational framework for the design of functional precursors suitable for nonlinear photolysis and advanced nanomaterial synthesis. Full article

Regulatory alerts regarding unauthorized use of colorants in food are frequently issued, often involving excessive concentration, improper declaration, or prohibited dyes. The illegal use of reactive textile dyes in food-related coloring preparations remains largely unrecognized, but confirmed cases have been reported in 2016 and 2020 and most recently in May 2025. This work presents the qualitative analyses’ results of a blue coloring powder for food use with regard to reactive dyes. The sample was labeled as a natural product, although it exhibited the color stability typical of artificial dyes. Prompting further investigation, combined spectroscopic, chromatographic and mass spectrometric methods were applied for the characterization and comparison with reference samples. In agreement with all analyses performed, strong evidence was found that the blue coloring powder contained several identical constituents with a reference sample of Reactive Blue 21. The overall composition suggests that both are complex mixtures of different phthalocyanines, suspected byproducts of synthesis, and various unknown compounds, rendering the powder unsuitable for human consumption. These findings emphasize the importance of tightened analytical controls regarding the unauthorized addition of textile dyes to food in order to maintain consumer safety. Full article

Nigella sativa, or black cumin, is used as a spice in cooking and as a food supplement like seeds or oil for its biological properties, including antioxidant capacity, anti-inflammatory action, and support for the immune system. In the present study, the chemical composition and biological activities of the Nigella sativa seeds’ fatty oil (NS) were investigated. The analytical composition was carried out by several techniques, such as GC-MS spectrometry and ¹H- and ¹³C-NMR spectroscopies using appropriate internal standards. The GC-MS analysis highlighted the presence of palmitic and linoleic acid as major compounds. The antioxidant potential was evaluated through the DPPH radical-scavenging assay, and, furthermore, the NS effect on intracellular reactive oxygen species (ROS) levels was assessed in HaCaT cells (non-tumorigenic human keratinocytes) under oxidative stress induced by hydrogen peroxide. The cytotoxic and genotoxic profiles were evaluated on Caco-2 cells (human colorectal adenocarcinoma cells) using the CCK-8 viability assay and the Comet assay, respectively. Overall, the results demonstrated that NS possessed antioxidant activity, as evidenced by concentration-dependent DPPH radical scavenging and reduced intracellular ROS levels in HaCaT cells under oxidative stress. In Caco-2 colorectal cancer cells, NS induced significant cytotoxicity and DNA damage at higher concentrations, suggesting potential genotoxic effects. These findings support the dual role of NS as a natural antioxidant and a promising candidate for nutraceutical and dermatological applications, including those targeting oxidative stress-related conditions and cancer. Full article

The unique cytochrome P450 BM3 from Priestia megaterium (syn. Bacillus megaterium) is renowned for its versatile high catalytic activity. The cyp102A1-LG23 gene encoding its CYP102A1-LG23 mutant variant was expressed in Escherichia coli and Mycolicibacterium smegmatis. The in vivo activity of the heterologous enzyme was assessed with respect to androstenedione (AD), androstadienedione (ADD), testosterone (TS) and dehydroepiandrosterone (DHEA). Alongside 7β-hydroxylation, the heterologous enzyme catalyzed the mono- and dihydroxylation of C19 steroids. For the first time, the formation of 7β-, 6β- and 11α-hydroxylated derivatives of ADD using a bacterial enzyme, as well as the hydroxylation of DHEA at the C7α and C7β positions, and its dihydroxylation with the formation of the 7α,15α-dihydroxylated derivative using the mutant cytochrome P450 BM3 were demonstrated. The steroid structures were confirmed using mass spectrometry and ¹H NMR spectroscopy. The advantages of using mycolicibacteria as a bacterial chassis for gene expression were also shown. The results demonstrate the unusual properties of the mutant cytochrome P450 BM3-LG23 and open up prospects for its application in the biotechnological production of valuable hydroxysteroids. Full article

The picornavirus 3CD protein is a precursor to the 3C main protease and the 3D RNA-dependent RNA polymerase. In addition to its functions in proteolytic processing of the virus polyprotein and cleavage of key host factors, the 3C domain interacts with cis-acting replication elements (CREs) within the viral genome to regulate replication and translation events. We investigated the molecular determinants of RNA binding to 3C using a wide range of biophysical and computational methods. These studies showed that 3C binds to a broad spectrum of RNA oligonucleotides, displaying minimal sequence and structure dependence, at least for these shorter RNAs. However, they also uncovered a novel aspect of these interactions, that is, 3C-RNA binding can induce liquid–liquid phase separation (LLPS), with 3CD–RNA interactions likewise leading to LLPS. This may be a general phenomenon for other 3C and 3C-like proteases and polyproteins incorporating 3C domains. These findings have potential implications in understanding virally induced apoptosis and the control of stress granules, which involve LLPS and include other proteins with known interactions with 3C/3CD. Full article

Accurate characterization of liquid manure properties, such as dry matter (DM), total nitrogen (TN), ammonium nitrogen (NH₄-N), and total phosphorus (TP), is essential for effective nutrient management in agriculture. This study investigates the use of near-infrared spectroscopy (NIRS) within the 941–1671 nm range, combined with advanced pre-processing and machine learning techniques to accurately predict the liquid manure properties. The predictive accuracy of NIRS was assessed by comparison with nuclear magnetic resonance (NMR) spectroscopy as a benchmark method. A number of 51 liquid manure samples were analyzed in the laboratory for the reference manure properties and scanned with NIRS and NMR. The NIR data underwent spectral pre-processing, which included two- and three-band index transformations and feature selection. Partial least squares regression (PLSR) and LASSO regression were employed to develop calibration models. According to the results, using cohort-tuned models, NIRS showed fair predictive accuracy for DM (R² = 0.78, RPD = 2.15) compared to factory-calibrated NMR (R² = 0.68, RPD = 0.81). Factory-calibrated NMR outperformed for chemical properties, with R² (RPD) of 0.89 (1.74) for TN, 0.97 (5.70) for NH₄-N, and 0.95 (2.64) for TP, versus NIRS’s 0.66 (1.68), 0.84 (2.45), and 0.84 (2.51), respectively. In this study with 51 samples, two- and three-band indices significantly enhanced NIRS performance compared to raw data, with R² increases of 34%, 57%, 25%, and 33% for DM, TN, NH₄-N, and TP, respectively. Feature selection efficiently reduced NIR spectral dimensionality without compromising the prediction accuracy. This study highlights NIRS’s potential as a portable tool for on-site manure characterization, with NMR providing superior laboratory validation, offering complementary approaches for nutrient management. Full article

A series of five cobalt(II) complexes, dichloro-bis(1-benzyl-benzimidazole)-cobalt(II) (1a), dichloro-bis[1-(4-fluorobenzyl)-benzimidazole]-cobalt(II) (1b), dichloro-bis((Z)-1-styryl-benzimidazole)-cobalt(II) (1c), dichloro-bis[(Z)-1-(2-fluorostyryl)-benzimidazole]-cobalt(II) (1d) and dichloro-bis(1-cinnamyl-benzimidazole)-cobalt(II) (1e), were evaluated in ethylene dimerization. Four of these complexes were described for the first time and fully characterized by IR, elemental analysis, mass and NMR spectroscopy. In the solid state, the cobalt atom exhibited a typical tetrahedral geometry and was found to be coordinated to two chlorine atoms and two benzimidazole rings. In the presence of 20 bar of ethylene and diethylaluminium chloride as a co-catalyst, the complex with styryl substituents on the benzimidazole rings, complex 1c, exhibited the highest activity with a turnover frequency of 3430 mol(ethylene)·mol(Co)⁻¹·h⁻¹. Full article

The synthesis of the first 2-alkyl-1,2,3-selenadiazol-2-ium salt is reported. Extensive spectroscopic characterization including Se-NMR was performed and the results are compared with those of the known 3-ium isomer. The yellow compound crystallizes in blocks as well as in columns. The crystal structures of both types are solved by X-ray diffraction and give final proof of the molecular structure. Full article

Background/Objectives: Metformin (Met) is a potent antidiabetic drug that also exhibits anticancer, antioxidant, and organ-protective properties. Luteolin (Lut), a naturally occurring flavonoid found in many plant species, possesses anticancer, antioxidant, and anti-inflammatory effects. Since both compounds affect cellular metabolism and oxidative balance, the analysis of metabolites produced in living cells provides insight into biochemical alterations occurring in cancer cells and enables monitoring of treatment response. Methods: In this study, Met (1–20 mM) and Lut (1–100 µM) were tested in vitro, both individually and in combination, to evaluate their effects on cell viability, free radical levels, and metabolite profile alterations in cancer and normal cell lines (MDA-MB-231, SW620, and V79). Cell viability was assessed using the MTT assay at two time points (24 h and 48 h), while reactive oxygen species (ROS) levels were measured after hydrogen peroxide stimulation (100 µM H₂O₂) using the DCF-DA assay. Metabolomic changes induced by Met and Lut were analyzed by ¹H NMR spectroscopy. Results: The analysis showed that Lut reduced the viability of MDA-MB-231 cells at both time points, whereas Met decreased viability only after prolonged incubation. Met did not inhibit the proliferation of SW620 colorectal cancer cells, while Lut reduced viability at higher concentrations (100 µM after 24 h, and 50–100 µM after 48 h). Conclusions: The combination of metformin and luteolin demonstrated additive effects in reducing cell viability and oxidative stress compared with single-compound treatments. Normal V79 fibroblasts responded to both Met and Lut, individually and in combination. Both compounds exhibited moderate antioxidant properties in cells exposed to 100 µM H₂O₂. Lut (25 µM) reduced free radical levels in MDA-MB-231 cells, whereas Met (2.5 mM) did so in SW620 cells. The combination of both compounds increased ROS levels in SW620 cells subjected to oxidative stress. Overall, co-treatment with metformin and luteolin altered metabolic pathways and induced changes in intra- and extracellular metabolite levels across all tested cell lines. The observed additive effects suggest that the combined use of metformin and luteolin may enhance anticancer and antioxidant responses, warranting further in vivo studies to confirm these interactions. Full article