Search Results (450)

Rhodium–porphyrin complexes are characterised by their ability to activate C-H and C-C bonds and, therefore, find applications in synthesis and catalysis. Axial rhodoporphyrin ligands are susceptible to photodissociation under the influence of light. DFT and TDDFT calculations were performed to investigate the mechanism of photodissociation of the methyl ligand from the methylrhodium(III)–porphyrin complex (MeRhPor). Various photolysis pathways of the rhodium–methyl bond were investigated, including photolysis from states in the Q and Soret bands. Photolysis from triplet states was also considered. Based on the calculations, the most probable mechanism for photodissociation of the methyl ligand was proposed. The methyl-rhodium binding energy in the methylrhodium(III)–porphyrin complex and the energy of formation of the rhodium–porphyrin radical dimer formed by methyl dissociation were also calculated. Full article

Background: Severe traumatic brain injury (sTBI) in adults remains a leading cause of mortality and disability worldwide. Early identification of reliable predictors of outcome is crucial for risk stratification and ICU management. Disturbances of hemostasis and metabolic factors such as body mass index (BMI) have been proposed as potential prognostic markers, but evidence remains limited. Methods: We conducted a retrospective, multicenter study including 307 adult patients with sTBI (Glasgow Coma Scale ≤ 8) admitted to three tertiary intensive care units in Ukraine between September 2023 and July 2024. All patients underwent surgical evacuation of hematomas and decompressive craniotomy. Laboratory parameters (APTT, INR, fibrinogen, platelets, D-dimer) were collected within 12 h of admission. BMI was calculated from measured height and weight. Predictive modeling was performed using L1-regularized logistic regression and Random Forest algorithms. Class imbalance was addressed with SMOTE. Model performance was assessed by AUC, accuracy, calibration, and feature importance. Results: The 28-day all-cause mortality was 32.9%. Compared with survivors, non-survivors had significantly lower GCS scores and higher INR, D-dimer, and APTT values. Very high VIF values indicated severe multicollinearity between predictors. Classical logistic regression was not estimable due to perfect separation; therefore, regularized logistic regression and Random Forest were applied. Random Forest demonstrated higher performance (AUC 0.95, accuracy ≈ 90%) than logistic regression (AUC 0.77, accuracy 70.1%), although results must be interpreted cautiously given the small sample size and potential overfitting. Feature importance analysis identified increased BMI, prolonged APTT, and elevated D-dimer as leading predictors of mortality. Sensitivity analysis excluding BMI still yielded strong performance (AUC 0.91), confirming the prognostic value of coagulation markers and GCS. Conclusions: Mortality in adult sTBI patients was strongly associated with impaired hemostasis, obesity, and low neurological status at admission. Machine learning-based modeling demonstrated promising predictive accuracy but is exploratory in nature. Findings should be interpreted with caution due to retrospective design, severe multicollinearity, potential overfitting, and absence of external validation. Larger, prospective, multicenter studies are needed to confirm these results and improve early risk stratification in severe TBI. Full article

Global production of fisheries and aquaculture products continues to increase, with the fisheries sector increasingly considered essential for global food security and nutrition. As public demand for seafood increases, implementation of safety management to minimize risks and ensure the safety of seafood products becomes important. This study was conducted to monitor 198 chemicals, comprising 161 pesticides and 37 pesticide metabolites, and to assess their risks in saltwater and freshwater fish in the Republic of Korea, based on the analysis of 471 fishery samples (298 saltwater and 173 freshwater). Among the fifteen saltwater fish species analyzed, pesticides were detected in eight species (croaker, flatfish, sea bass, flounder, snapper, yellow tail, salmon, and gizzard shad) and in all seven freshwater species (carp, catfish, crucian carp, eel, leather carp, loach, and trout). Four pesticides (ethoxyquin, lufenuron, metaflumizone, and propiconazole) were detected in saltwater fish, while nine pesticides (ethoxyquin, ipfencarbazone, isoprothiolane, lufenuron, metaflumizone, oxadiargyl, pendimethalin, phoxim, and trichlorfon) were found in freshwater fish. Ethoxyquin was the most frequently detected pesticide in both fish types, mostly in the form of its metabolite, the ethoxyquin dimer. The estimated daily intake (EDI) was calculated based on the maximum concentrations of pesticides detected and the average consumption of fishery products by sex and age group. The hazard quotients, expressed as a percentage of acceptable daily intake (%ADI) and calculated using the EDI and ADI of the pesticides detected, were evaluated to be no more than 5.6%. These results suggest that consumption of saltwater and freshwater fish in the Republic of Korea poses a low risk to human health. This approach can be applied to pesticide residue monitoring and risk assessment in the fisheries sector, providing valuable data for evaluating contamination levels and supporting the regulation and management of chemical residues. Full article

Nerolidol (REL), a sesquiterpene with cis and trans isomers, exhibits diverse bioactive and sensory properties. In this study, we integrate single-crystal X-ray diffraction (SC-XRD), molecular docking, molecular dynamics (MD) simulations, and MM/GBSA binding free energy calculations to investigate its inclusion behavior in β-cyclodextrin (β-CD). Crystallization from a cis/trans mixture yielded a complex containing exclusively the trans isomer, forming a 2:1 host–guest assembly where a head-to-head β-CD dimer encapsulates one trans-REL molecule in an extended conformation. Computational models of cis-REL (bent c1 and extended c8 conformers) also stabilized within the β-CD cavity, with the extended conformer showing the most favorable dynamics. The computed binding affinities for all complexes differed by less than the estimated MM/GBSA uncertainty, indicating no statistically significant preference. Since cis/trans separation of nerolidol and related long-chain terpenoids is of considerable interest, our findings suggest that crystallization selectivity in β-CD inclusion complexes cannot be rationalized solely by binding affinity; instead, it likely arises from crystal packing forces and conformational preferences that govern the solid-state assembly. Full article

Background/Objectives: Acute ischemic stroke is a leading cause of mortality and long-term disability globally, with limited reliable early predictors of functional outcomes and survival. This study aimed to assess the prognostic value of two novel predictors: the hypoperfusion intensity ratio calculated from mean transit time and time-to-drain maps (HIR-MTT–TTD), derived from computed tomography perfusion (CTP) imaging parameters, and the Inflammation–Coagulation Index (ICI), which integrates systemic inflammatory (C-reactive protein and white blood cell count) and hemostatic (D-dimer) markers. Methods: This prospective, single-center observational study included 60 patients with acute ischemic stroke treated with intravenous thrombolysis and underwent pre-treatment CTP imaging. HIR-MTT–TTD evaluated collateral status and perfusion deficit severity, while ICI integrated C-reactive protein (CRP), white blood cell (WBC) count, and D-dimer levels. Functional outcomes were assessed using the National Institutes of Health Stroke Scale (NIHSS), Barthel Index, and modified Rankin Scale (mRS) at 24 h, 3 months, and 1 year. Results: Of 60 patients, 53.3% achieved functional independence (mRS 0–2) at 1 year. Unadjusted Cox models showed HIR-MTT–TTD (HR = 6.25, 95% CI: 1.48–26.30, p = 0.013) and ICI (HR = 1.08, 95% CI: 1.00–1.17, p = 0.052) were associated with higher 12-month mortality, worse mRS, and lower Barthel scores. After adjustment for age, BMI, smoking status, and sex, these associations became non-significant (HIR-MTT–TTD: HR = 2.83, 95% CI: 0.37–21.37, p = 0.314; ICI: HR = 1.07, 95% CI: 0.96–1.19, p = 0.211). Receiver operating characteristic (ROC) analysis indicated moderate predictive value, with ICI (AUC = 0.756, 95% CI: 0.600–0.867) outperforming HIR-MTT–TTD (AUC = 0.67, 95% CI: 0.48–0.83) for mortality prediction. Conclusions: The study introduces promising prognostic tools for functional outcomes. Elevated HIR-MTT–TTD and ICI values were independently associated with greater initial stroke severity, poorer functional recovery, and increased 1-year mortality. These findings underscore the prognostic significance of hypoperfusion intensity and systemic thrombo-inflammation in acute ischemic stroke. Combining the use of the presented indices may enhance early risk stratification and guide individualized treatment strategies. Full article

Supports used in heterogeneous metallic catalysts serve as a structural skeleton across which metallic nanoparticles are dispersed, but specific properties of the supports may also determine the behavior of these nanoparticles in catalytic processes. For example, it is known that among various properties of crystalline alkaline earth metal oxides serving as supports, the ability of their surface sites to donate electrons, that is their basicity, has an influence on the characteristics of the adsorbed metal. In the present work, the influence of MeO (Me = Mg, Ca, and Sr) basicity on the adsorption of Pb on the (100) surface of MeO crystals is studied by means of a dispersion-corrected density functional theory (DFT-D) computational method. The DFT-D calculations have characterized essential structural parameters, energetics, and the distribution of the electron charge for the Pb atoms and Pb dimers adsorbed at the regular O²⁻ and defective F_s centers of MeO(100). It has been observed that an increase in the basicity of MeO(100) in the sequence MgO < CaO < SrO results in a more energetically favorable effect of Pb adsorption, a stronger interaction between Pb and the surface, and a greater amount of electron charge acquired by the adsorbed Pb atoms and dimers. These findings contribute to a better understanding of how support basicity may modulate certain characteristics of MeO-supported metallic catalysts containing Pb as an additive. From a computational viewpoint, this work shows that the inclusion of spin–orbit relativistic correction in the DFT-D calculations leads to a significant reduction in the strength of the interaction between Pb and MeO(100), but it does not change the aforementioned trend in the strength of this interaction as a function of support basicity. Full article

Villosiclava virens (anamorph: Ustilaginoidea virens), the causal fungal pathogen of rice false smut, has been found to produce various secondary metabolites. The albino strain LN02 is a natural albino phenotype mutant of V. virens due to its inability to produce ustilaginoidins. The fermentation of V. virens LN02 was performed in solid rice medium to obtain fungal cultures, which were chemically investigated. After removing the known metabolites, two new dimeric sorbicillinoids, namely ustisorbicillinols G (1) and H (2), were isolated from the ethyl acetate extract. Their structures were elucidated using spectroscopic data analyses and quantum chemical calculations. Compounds 1 and 2 displayed antibacterial activity towards Ralstonia solanacearum, Agrobacterium tumefaciens and Bacillus subtilis, with median inhibitory concentration (IC₅₀) values of 19.76–25.43 μg/mL for 1 and 25.35–45.48 μg/mL for 2. The discovery of new sorbicillinoids will increase the diversity of the secondary metabolites of V. virens and provide candidates for the creation of new antimicrobials as well. Full article

Human Interleukin-6 (hIL-6) is a pro inflammatory cytokine that binds to its receptor, IL-6Rα followed by binding to gp130 and subsequent dimerization to form a hexamer signaling complex. As a critical inflammation mediator, hIL-6 is associated with a diverse range of diseases and monoclonal antibodies in clinical use that either target IL-6Rα or hIL-6 to inhibit signaling. Here, we perform high-throughput structure-based computational screening using ensemble docking for small-molecule antagonists for which the target conformations were taken from 600 ns long molecular dynamics simulations of the apo protein. Prior knowledge of the contact sites from binary complex studies and experimental work was incorporated into the docking studies. The top 20 scoring ligands from the in silico studies after post analysis were subjected to in vitro functional assays. Among these compounds, the ligand with the second-highest calculated binding affinity experimentally showed an ~84% inhibitory effect on IL6-induced STAT3 reporter activity at 10 μM concentration. This finding may pave the way for designing small-molecule inhibitors of hIL-6 of therapeutic significance. Full article

Water’s unique physicochemical properties arise from its dynamic hydrogen-bonding network, yet the precise molecular threshold at which these cooperative behaviors emerge remains a key question. This study employed nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) calculations to investigate the evolution of hydrogen bonding strength in small water clusters, ranging from dimers to pentamers. The observed exponential increase in NMR chemical shift up to the pentamer reflects growing hydrogen bond cooperativity, identifying the (H₂O)₅ cluster as a critical structural and energetic threshold. At this size, the network achieves sufficient connectivity to support key bulk-like phenomena such as proton transfer and dielectric relaxation. These conclusions were corroborated by complementary FT-IR and electrochemical impedance spectroscopy (EIS) measurements of bulk water. Our results position the water pentamer as the molecular onset of emergent solvent behavior, effectively bridging the divide between discrete clusters and the macroscopic properties of liquid water. Full article

The polycondensation of silica from soluble silicic acid is at the basis of several chemical processes. The usual industrial route requires harsh pH conditions and high concentrations of the precursor molecules, not to mention a thermal treatment for obtaining condensed structures. On the other hand, biological organisms can promote the precipitation of silica under physiological conditions, including temperature and pH, and low concentrations of precursors. The key to this process is the use of polycationic molecules. Despite the relevance of these processes in modern industrial inorganic chemistry, this fascinating process is still not completely understood. Recent studies converge in pointing out that the role of the polycation is to create supersaturation of silicic acid in its immediate proximity, which would explain the impact of the polycation on the reaction rates. However, it remains unclear whether these polycations also directly influence the reaction mechanism at a molecular level. In this manuscript, we address this question by analyzing the reaction pathway of silicic acid dimerization in the presence of guanidinium as a mimic of the arginine side chain, through DFT calculations. We found that the impact on the reaction pathway is minimal, which strengthens the hypothesis of the local supersaturation driven by the polycationic molecules. Full article

Endotheliopathy plays an essential role in the pathophysiology of COVID-19. The endothelial activation and stress index (EASIX) indicates endothelial dysfunction. We aimed to investigate the relationship between a high EASIX score and mortality in patients with COVID-19. We retrospectively reviewed COVID-19 patients admitted to the ICU (intensive care unit) of the Ankara Bilkent City Hospital. We recorded hematological and biochemical parameters at the ICU admission and further calculated EASIX with the following equation: EASIX = Lactate dehydrogenase (U/L) × creatinine (mg/dL)/platelet count (10⁹/L). Statistical comparisons were made between the surviving and non-surviving groups in terms of EASIX. The median EASIX score was 1.2 (0.7–2.0) in the survivor group and a median of 2.5 (1.6–4.2) in the non-survivor group (p < 0.001). The mean log2-EASIX was 0.2 ± 0.9 in the survivor group and 1.3 ± 1.2 in the non-survivor group (p < 0.001). Lactate dehydrogenase, creatinine, Troponin I, D-dimer, procalcitonin, ferritin, and IL-6 were statistically significantly higher in the non-survivor group compared to the survivor group. The receiver operating characteristic (ROC) curve analysis showed that the cut-off value of the EASIX score was 2.05 (The area under the curve [AUC] = 0.764, p = 0.001, 95% CI: 0.662–0.847). Our study showed an association between high EASIX scores and poor prognosis in COVID-19 patients. Lactate dehydrogenase, creatinine, Troponin I, D-dimer, procalcitonin, ferritin, IL-6, EASIX, and log2-EASIX were statistically significantly higher in the non-survivor group compared to the survivor group. Being old and having chronic kidney disease increases the risk of death. Eventually, EASIX can be used to predict mortality in COVID-19 patients. Full article

Objectives: Systemic inflammation, coagulopathy, and multiorgan dysfunction are common in critically ill patients and contribute significantly to mortality. Serum albumin and D-dimer are routinely used biomarkers that reflect nutritional status and coagulation activity, respectively. This study aimed to investigate the prognostic value of the albumin-to-D-dimer ratio (ADR) in predicting 30-day mortality among patients admitted to the intensive care unit (ICU) and undergoing mechanical ventilation. Methods: This retrospective cohort study included 162 adult patients who underwent invasive mechanical ventilation in the ICU of a tertiary care center between January 2021 and December 2023. Demographic data, comorbidities, and laboratory values—such as serum albumin, D-dimer, lactate, CRP, BUN, creatinine, INR, and platelet count—were recorded within the first 24 h of ICU admission. The albumin-to-D-dimer ratio (ADR) was calculated by dividing serum albumin (g/dL) by D-dimer (μg/mL). The patients were stratified into tertiles based on ADR values: low (<0.95), intermediate (0.95–1.45), and high (>1.45). The association between the ADR and 30-day mortality was analyzed using multivariate logistic regression and receiver operating characteristic (ROC) curve analysis. Results: Of the 162 patients included in the study, 61 (37.7%) died within 30 days. The patients who died had significantly lower ADR values at ICU admission compared to survivors (1.02 ± 0.43 vs. 1.56 ± 0.52, p < 0.001). In the multivariate logistic regression model, a lower ADR remained an independent predictor of 30-day mortality (OR: 0.39; 95% CI: 0.26–0.58; p < 0.001), even after adjusting for age, lactate, creatinine, INR, and other relevant clinical variables. ROC curve analysis demonstrated that the ADR had the highest discriminative performance among all the evaluated parameters, with an AUC of 0.802 (95% CI: 0.728–0.875; p < 0.001). The optimal cut-off value for the ADR was identified as <1.05, yielding a sensitivity of 78.7% and a specificity of 71.4% in predicting 30-day mortality. Conclusions: The ADR is independently associated with 30-day mortality in mechanically ventilated ICU patients and may serve as a useful early prognostic marker. However, given the retrospective, single-center nature of this study, these findings should be interpreted with caution. Further prospective, multicenter studies are needed to validate the clinical utility of the ADR. Full article

Three new naphthalene–chroman dimer derivatives, daldinaphchromes A–C (1–3), two new chroman derivatives, daldichromes A (5) and B (6), along with five known compounds (4, 7–10) were isolated from the mangrove-derived fungus Daldinia eschscholzii HJX1P2. Their structures and stereochemistries were elucidated through detailed NMR and MS analyses, calculated electronic circular dichroism, and comparison with previously reported data. Compound 1 demonstrated inhibitory effects on nitric oxide (NO) production in LPS-induced RAW 264.7 cells, with an IC₅₀ value of 62.9 µM, and more effectively suppressed the expression of interleukin (IL)-6 than dexamethasone. A further mechanistic study suggested that 1 could prohibit the expression of iNOS in RAW 264.7 cells, and the molecular docking study suggested a possible interaction between 1 and the iNOS protein. Compounds 7 and 8 exhibited moderate to potent DPPH radical scavenging activity, with IC₅₀ values of 117.4 and 46.2 µM, respectively, compared with the positive control ascorbic acid (IC₅₀ = 45.6 µM). Compounds 4 and 10 showed ABTS⁺ radical scavenging activity, with IC₅₀ values of 66.6 and 33.2 µM, respectively, which were equal to or lower than that of the positive control vitamin C (IC₅₀ = 59.7 µM). Compounds 1–3, 7, and 9 showed antibacterial activity against three Staphylococcus aureus strains, with MIC values of 74.4–390.6 μM. Full article

This work presents the synthesis routes for the first representatives of cadmium complexes based on 1,2-bis(arylimino)acenaphthene (Ar-bian). The reaction of CdCl₂ with bis-(2,4,6-trimethylphenylimino)acenaphthene (tmp-bian) in a 1-to-1 molar ratio led to a dimeric complex [Cd₂(tmp-bian)₂Cl₂(µ-Cl)₂] (1). Further treatment of complex 1 with silver triflate as a chloride-eliminating agent, followed by the addition of one equivalent of tmp-bian, resulted in the formation of a mixture consisting of [Cd₂(tmp-bian)₂(H₂O)₄(µ-Cl)₂](OTf)₂ (2) and [Cd(tmp-bian)₂(OTf)₂] (3). To obtain complex 3 in its individual form, a reaction of Cd(OTf)₂ with two equivalents of tmp-bian was carried out. The characterization of the complexes was conducted through a range of analytical methods, including X-ray diffraction analysis, elemental analysis, as well as IR and ¹H NMR-spectroscopies. Redox properties of 1 and 3 were investigated by means of cyclic voltammetry. Cyclic voltammograms revealed irreversible reduction processes centered on the tmp-bian ligand, which were confirmed by quantum chemical calculations. Full article

A detailed characterization of metal clusters bound at the surface of crystalline metal oxide supports is crucial for identifying their structure–property relationships relevant to practical applications. Theoretical investigations based on first-principles calculations have proven to be helpful in characterizing supported metal clusters. In this work, the adsorption of an Sn dimer on the regular and defective (100) surfaces of MgO crystal was studied by means of density functional theory (DFT) calculations. The investigated defects included ${\mathrm{F}}_{\mathrm{s}}^0$, ${\mathrm{F}}_{\mathrm{s}}^{+}$, and ${\mathrm{F}}_{\mathrm{s}}^{2+}$ oxygen vacancies on MgO(100). From the results of the calculations, it is clear that the adsorption of Sn₂ at the ${\mathrm{F}}_{\mathrm{s}}^0$ and ${\mathrm{F}}_{\mathrm{s}}^{+}$ centers is stronger than that occurring on the defect-free MgO(100) surface. While the triplet spin multiplicity of a free Sn dimer tends to be preserved upon its adsorption at the ${\mathrm{F}}_{\mathrm{s}}^{2+}$ center, spin quenching is favored for the dimer adsorbed at the regular O²⁻ and defective ${\mathrm{F}}_{\mathrm{s}}^0$ and ${\mathrm{F}}_{\mathrm{s}}^{+}$ centers. The topological analysis of the electron density for the adsorbed dimer was carried out within the quantum theory of atoms in molecules (QTAIM). The calculated values of QTAIM parameters for the Sn-Sn bond of the adsorbed dimer do not differ radically from the corresponding values for the dimer in the gas phase. Full article