Search Results (48)

Beyond gas transport, red blood cells (RBCs) have emerging roles regarding innate immunity, regulating blood flow, and participating in nutrient transport, which can be engineered as drug delivery systems since they contribute to maintaining water homeostasis. Following extensive thermoanalytical studies of human blood plasma, our working group investigated the properties of RBCs, examining their role in healthy and in different disease states by using differential scanning calorimetry (DSC) and the deconvolution of the resulting thermal curve. In the first study, guinea pigs were treated with intraperitoneal chemotherapy. Cyclophosphamide treatment showed a dose-dependent difference between the thermal parameters of control and treated samples, indicating that DSC can be used in this area. Following deconvolution of the DSC studies, the changes can be attributed to the damaged compounds. In the second part of our study, a method for the thermal analysis and deconvolution of RBCs in patients with lower limb ischemia during a three-month cilostazol treatment was developed. The control DSC curve showed 5–6 distinct thermal domains, and in contrast to other drug treatments, this remained stable throughout the entire study period. No effects of stiffness or compact were caused by the anticancer drug cyclophosphamide were observed in the structure of RBCs. These preliminary results highlight the uniqueness of thermodynamic studies of RBCs and provide a fingerprint-like identification of a given individual or disease state. Full article

The paper presents the synthesis of new naphthyl-containing derivatives of thiosemicarbazide and thiourea, their water-soluble inclusion complexes with β-cyclodextrin, as well as an assessment of their potential antiviral and hemorheological activity. As a criterion for the specific antiviral effect of new compounds, their chemotherapeutic indices were calculated using predictive analytics tools driven by artificial intelligence and molecular docking methods. Molecular docking studies with three protein targets PknB (2FUM), DprE1 (6HEZ), and InhA (1ENY) confirmed strong and specific ligand–protein interactions. The effects of structural features of new compounds on the rheological characteristics of blood were considered, and the most promising samples were identified for further in-depth in vitro study of their specific biological activity. The performed thermoanalytical study showed that the structure of the included ligand, as well as the shape of the receptor, significantly affect the thermal stability and kinetic parameters of the decomposition of the inclusion complex. In silico evaluation of the newly synthesized compounds revealed promising biological activity profiles, with all compounds demonstrating predicted antimycobacterial and antituberculosis potential. In silico analysis of the newly synthesized compounds revealed favorable biological activity profiles, with all candidates demonstrating predicted antimycobacterial and antituberculosis potential. Full article

This study presents a comparative thermal and kinetic analysis of three benzimidazole derivatives used in the pharmaceutical field: fenbendazole, mebendazole, and flubendazole. The investigations were carried out using thermoanalytical methods, including thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), in order to evaluate thermal stability, decomposition stages, and to calculate kinetic parameters. The obtained data were processed using isoconversional methods (Ozawa–Flynn–Wall, and Friedman) and non-parametric method (NPK) to determine activation energies and degradation mechanisms. The results revealed significant differences among the three compounds regarding their thermal stability and decomposition behavior, influenced by molecular structure and aromatic substituents. Furthermore, the comparative analysis provides valuable insights for optimizing technological processes, assessing stability in pharmaceutical formulations, and expanding research on the therapeutic potential of these compounds, including in oncological studies. Overall, the study contributes to a deeper understanding of the relationship between chemical structure and thermal stability in benzimidazole derivatives. Full article

Background: Aneurysmal subarachnoid hemorrhage (aSAH) induces complex systemic inflammatory and metabolic responses that may influence clinical outcome. DSC provides an integrative biophysical readout of proteome-level thermodynamic behavior rather than protein-specific identification or quantification; however, its applicability in neurocritical conditions remains largely unexplored. This pilot study aimed to explore whether serum DSC profiles show preliminary associations with clinical severity and neurological outcomes after aSAH. Methods: Serum samples collected on day 1 after aSAH were analyzed by DSC and compared with healthy control samples. A small patient cohort was stratified according to clinical severity and neurological outcome. Thermograms were evaluated based on melting temperatures (Tm), calorimetric enthalpy (ΔHcal), heat capacity changes (ΔCp), and the relative contributions of major serum protein components. Results: Healthy controls exhibited characteristic DSC profiles dominated by a cooperative albumin transition at approximately 65–66 °C. In this limited cohort, patients with severe clinical conditions and unfavorable outcomes displayed marked thermogram reorganization, including increased albumin Tm, reduced unfolding cooperativity, decreased ΔCp, and enhanced high-temperature immunoglobulin-related contributions. Patients with mild condition and favorable outcome showed profiles more similar to those of the controls. Notably, patients with severe conditions but favorable outcomes demonstrated heterogeneous albumin-related thermal domains, which may reflect individual-level variability and suggesting dynamic proteomic heterogeneity at the early post-ictus phase. Given the small group sizes, these patterns should be interpreted as exploratory and hypothesis-generating. Conclusions: This pilot exploratory study suggests that serum DSC may capture preliminary thermoanalytical patterns associated with clinical outcomes after aSAH. While the findings indicate the potential of DSC as a systems-level tool in neurocritical care, larger, well-powered studies are required to validate these observations and assess their robustness and generalizability. Full article

Fire-retardant intumescent coatings offer an effective means of enhancing the fire resistance of combustible substrates such as wood. These coatings have a complex chemical composition and, when exposed to temperatures above 200 °C, undergo an intumescent reaction accompanied by the release of non-flammable gases, forming an expanded, charred layer with low thermal conductivity. This provides thermal insulation and acts as a physical barrier against heat, oxygen, and flammable volatiles. In this study, the applicability of several thermoanalytical techniques for evaluating the performance of three different intumescent coatings applied to spruce wood was investigated. Simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that coating No. 3 was the most efficient, initiating substrate protection at the lowest temperature and reducing the combustion enthalpy by approximately 50% compared to uncoated wood. DSC-microscopy visualization enabled direct observation of the intumescent expansion, degradation of the carbonized protective layer, and delayed thermal decomposition of coated wood. Furthermore, a comparison between TGA-MS and TGA-IST16-GC-MS demonstrated the superiority of chromatographic separation for identifying evolved gaseous products. While TGA-MS is effective for detecting small gaseous species (e.g., H₂O, CO₂, formaldehyde), TGA-IST16-GC-MS enables the deconvolution of many degradation products evolving simultaneously, allowing for distinction between flame-retardant-related species, polymer backbone fragments, nitrogen-rich heterocycles, and small oxygenated molecules in the most effective coating. Full article

In this article, the thermal and mechanical properties of mortars reinforced with polypropylene (PP) fibres have been studied. Particularly, the effect of polypropylene fibres’ addition on the thermal behaviour of fine-grained building mortars at high temperatures was studied using simultaneous thermal analysis. Two types of polypropylene fibres, differing in shape and size, were used as fillers. The thermal behaviour of cement mortar samples with and without fibres was described. Special attention was given to the thermal behaviour of fibre-reinforced cement mortars subjected to the high temperatures of 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, and 600 °C. Comparative studies using simultaneous thermal analysis (STA) were also performed for non-heated samples (20 °C). The TG, DTG, and DTA curves were analysed to investigate the effects related to the dehydration and the decomposition of hydration and carbonation products. Compared to mortar samples without fibres, the results showed that the presence of polypropylene fibres contributes to an increase in the thermal stability of the samples. It has been proven that the impact of the type and amount of PP fibres in the tested range (1.8 kg/m³ vs. 3.6 kg/m³) on the thermal stability of specimens of tested cement composites was found not to be significantly visible. Next, extensive research was performed on the impact of fire environmental exposure on the variability in the strength parameters of the mortars. Tensile strength tests were conducted based on the standards specified by the Polish Committee for Standardization. The research material consisted of high-strength, fine-grained building mortars, modified by an original method with polypropylene fibres at concentration of 1.8 kg/m³, 3.0 kg/m³, and 3.6 kg/m³. For reference, ordinary mortars without fibres were used, as well. Tensile strength was evaluated for mortar samples, which were exposed to temperatures of 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, and 600 °C, respectively. Special attention was paid to the thermal behaviour of cement mortars reinforced with polypropylene (PP) fibres, subjected to high temperatures. Based on the obtained test results, a detailed statistical analysis was developed, along with comprehensive temperature–parameter relationships, which could enable an approximate post-failure assessment of the mortar’s condition. The main outcomes of this paper include optimal fibre dosage, which is 3.6 kg/m³, identified optimal fibre type, namely F fibre, as well as plateau in tensile strength for temperatures between 200 °C and 400 °C for fibre-reinforced samples. Full article

Estrogens are cholesterol-derived hormones, with four endogenous estrogens being presented in the scientific literature, namely, estradiol, estrone, estriol, and estetrol. In this study, we aim to obtain a complete thermoanalytical profile for the three most important endogenous estrogens: estradiol, estriol, and estrone. To achieve this, the TG/DTG were registered in non-isothermal conditions at five different heating rates (β = 2, 4, 6, 8, and 10 °C min⁻¹). To describe the mechanisms of the degradation processes, a complex kinetic analysis was performed by applying a preliminary method (ASTM E698), two isoconversional methods (Flynn–Wall–Ozawa and Friedman), and the non-parametric kinetic method. The results indicate that estradiol undergoes a single-step degradation process, while estriol and estrone present a complex degradation process. The determination of the shelf life of pharmaceutical products represents a critical factor in ensuring their safety and efficacy. This parameter can be estimated from the activation energy derived from non-isothermal experiments through the application of the Arrhenius equation and appropriate kinetic models. Full article

The focus in microplastic research has shifted from marine ecosystems towards freshwater ecosystems. Still, most studies are based on small sample numbers, both spatially and temporally. Little is known about the spatiotemporal variability of microplastics (MPs) in large river systems such as the Rhine River, Germany. Within our study, we performed four cross-sectional sampling campaigns at two sites in the Rhine River, at Koblenz and Emmerich, involving depth-distributed sampling over a particle size range from 10 µm to 25 mm. For plastic particle analysis, we used both optical and thermoanalytical approaches to determine mass-based polymer concentrations. Our results show that MP variability within the water column is complex, but mostly follows the particles density: the ratio between superficial MPs concentration and mean concentration of the verticals was >1 for lighter polymers with a density below 1.04 g/cm³ and <1 for polymers with a density above 1.04 g/cm³ among all size classes with only a few exceptions, even though the Rouse theory would indicate a more homogeneous distribution for small particle sizes. Large sampling volumes are essential, particularly for larger MP particles, as the coefficient of variation rises with particle size. At our study sites, no significant lateral variation was apparent, while during a flood event, MP concentrations were significantly higher than during low and mean water stages. This study is the first to (i) gain insights into cross-sectional MPs distribution in the Rhine River and (ii) account for particle mass concentrations, and thus lays the foundation for potential future MPs flux monitoring. Full article

A new complex, tetrakis(1,10-phenanthroline)-bis(succinate)-(µ₂-oxo)-bis(iron(III)) nonahydrate, [Fe₂(Phen)₄(Succinate)₂(μ-O)](H₂O)₉, was synthesized using the slow evaporation method. This study provides a comprehensive characterization of this coordination compound, focusing on its structural, spectroscopic, and thermal properties, which are relevant for applications in catalysis, material science, and chemical engineering processes. Single-crystal X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared (FT-IR), ultraviolet-visible (UV-Vis) spectroscopy, and thermoanalytical analyses were employed to investigate the material properties. Intermolecular interactions were further explored through Hirshfeld surface analysis. XRD results revealed a monoclinic crystal system with the C2/c space group, lattice parameters: a = 12.7772(10) Å, b = 23.0786(15) Å, c = 18.9982(13) Å, β = 93.047(2)°, V = 5594.27(7) ų, and four formulas per unit cell (Z = 4). The crystal packing is stabilized by C–H⋯O, C–O⋯H, C–H⋯π, and π⋯π intermolecular interactions, as confirmed by vibrational spectroscopy. The heteroleptic coordination environment, combining weak- and strong-field ligands, results in a low-spin state with an estimated crystal field stabilization energy of −4.73 eV. Electronic properties indicate direct allowed transitions (γ = 2) with a maximum optical band gap of 2.66 eV, suggesting potential applications in optoelectronics and photochemical processes. Thermal analysis demonstrated good stability within the 25–136 °C range, with three main stages of thermal decomposition, highlighting its potential for use in high-temperature processes. These findings contribute to the understanding of Fe(III)-based complexes and their prospects in advanced material design, catalytic systems, and process optimization. Full article

Carvedilol (CARV) is a nonselective beta and alpha-1 adrenoceptor antagonist commonly indicated for chronic heart failure and hypertension. Its clinical potential is limited by its low aqueous solubility, resulting in poor bioavailability. Encapsulation of CARV by cyclodextrins (CDs) was performed to exceed its solubility-related barriers. This study examines the impact of the CD type and ethanol, as a co-solvent used in the preparation step, on the complexation of CARV with two β-CD derivatives. The inclusion complexes (ICs) were prepared employing the kneading method and investigated using different analytical techniques, including thermoanalytical methods, powder X-ray diffractometry (PXRD), universal attenuated total reflectance Fourier transform infrared (UATR-FTIR) spectroscopy, UV spectroscopy and saturation solubility studies. The binary products of CARV with heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD) and randomly methylated β-cyclodextrin (RM-β-CD) exhibit different thermal behavior, different FTIR spectral and diffractometric profiles from those of the parent compounds, emphasizing the interaction between the components and the IC formation. CARV solubility increased 1.78 to 3.32 times as a result of drug complexation with CDs. Analytical data indicate a significant influence of both solvent systems and CD type on the IC solubility, highlighting the CARV/DM-β-CD IC as a promising entity for further research to obtain new formulations containing CARV with improved bioavailability. Full article

Background: Olmesartan medoxomil (OLM) is the prodrug of olmesartan, an angiotensin II type 1 receptor blocker that has antihypertensive and antioxidant activities and renal protective properties. It exhibits low water solubility, which leads to poor bioavailability and limits its clinical potential. To improve the solubility of OLM, a host–guest inclusion complex (IC) between heptakis(2,6-di-O-methyl)-β-cyclodextrin (DMβCD) and the drug substance was obtained. Along with active substances, excipients play a crucial role in the quality, safety, and efficacy of pharmaceutical formulations. Therefore, the compatibility of OLM/DMβCD IC with several pharmaceutical excipients was evaluated. Methods: IC was characterized in both solid and liquid states, employing thermoanalytical techniques, universal-attenuated total reflectance Fourier-transform infrared spectroscopy, powder X-ray diffractometry, UV spectroscopy, and saturation solubility studies. Compatibility studies were carried out using thermal and spectroscopic methods to assess potential physical and chemical interactions. Results: The 1:1 OLM:DMβCD stoichiometry ratio and the value of the apparent stability constant were determined by means of the phase solubility method that revealed an A_L-type diagram. The binary system showed different physicochemical characteristics from those of the parent entities, supporting IC formation. The geometry of the IC was thoroughly investigated using molecular modeling. Compatibility studies revealed a lack of interaction between the IC and all studied excipients at ambient conditions and the thermally induced incompatibility of IC with magnesium stearate and α-lactose monohydrate. Conclusions: The results of this study emphasize that OLM/DMβCD IC stands out as a valuable candidate for future research in the development of new pharmaceutical formulations, in which precautions should be considered in choosing magnesium stearate and α-lactose monohydrate as excipients if the manufacture stage requires temperatures above 100 °C. Full article

Angiotensin II receptor antagonists are tetrazole derivatives used in the treatment of high blood pressure, and are also indicated for the treatment of heart failure (NYHA class II-IV). They are used alone or in combination with other classes of antihypertensives or diuretics for the effective management of high blood pressure. In this study, we aim to evaluate the thermal stability and degradation kinetics for the principal compounds used in therapy from this class, namely telmisartan, valsartan, olmesartan medoxomil, and losartan potassium. To obtain the thermoanalytical data for the kinetic investigations, the TG and DTG curves were registered at five different heating rates (β = 2, 4, 6, 8, and 10 °C min⁻¹). The kinetic methods used were a preliminary ASTM E698 method and two isoconversional methods: Flynn–Wall–Ozawa and Friedman. For each molecule, the results showed complex decomposition processes consisting of complex reaction sequences. Full article

The development of a methodological approach to detecting the presence of flame retardants in building materials and products and finding their concentration is an essential part of the performance evaluation of flame retardants for timber. The above issue is a relevant constituent of supervision over fire safety compliance at construction facilities. Thermal analysis was used in this research project to (1) detect the presence of flame retardants in timber, and (2) identify methods of their application. Comparative experiments were conducted to detect the presence and effectiveness of flame retardants applied to the surface and inner layers of specimens of timber planken (façade board) at a construction facility. Relevant values, characterizing the thermal decomposition of timber specimens, enable predicting the heat flux rate that triggers ignition. A quick test, conducted to check the flammability of specimens, confirmed the authors’ hypothesis. The study revealed principal (relevant) thermo-analytical criteria for the fire resistance of timber impregnated with combustion retardants using different methods of impregnation. A methodological approach to studying relevant thermo-analytical characteristics was developed to evaluate the efficiency of (1) fire resistance of timber products and (2) fireproofing techniques. Flammability and combustibility of timber impregnated with fire retardants was prognosticated. It was revealed that the proposed methodology can monitor the efficiency of fireproofing applied to façade structures made of pine timber. Full article

Tutton salts have received considerable attention due to their potential applications in thermochemical energy storage (TCHS) systems. This technology requires high-purity materials that exhibit reversible dehydration reactions, significant variations in dehydration enthalpy, and high-temperature melting points. In this study, K₂Cu(SO₄)₂(H₂O)₆ Tutton salt in the form of single crystals was grown using the slow solvent evaporation method. Their structural, morphological, and thermal characteristics are presented and discussed, as well as temperature-induced phase transformations. At room temperature, the salt crystallizes in a monoclinic structure belonging to the P2₁/a space group, which is typical for Tutton salts. The lack of precise control over the solvent evaporation rate during crystal growth introduced structural disorder, resulting in defects on the crystal surface, including layer discontinuities, occlusions, and pores. Thermoanalytical analyses revealed two stages of mass loss, corresponding to the release of 4 + 2 coordinated H₂O molecules—four weakly coordinated and two strongly coordinated to the copper. The estimated dehydration enthalpy was ≈ 80.8 kJ/mol per mole of H₂O. Powder X-ray diffraction measurements as a function of temperature showed two phase transformations associated with the complete dehydration of the starting salt occurring between 28 and 160 °C, further corroborating the thermal results. The total dehydration up to ≈ 160 °C, high enthalpy associated with this process, and high melting point temperature make K₂Cu(SO₄)₂(H₂O)₆ a promising candidate for TCHS applications. Full article

Emerging pharmaceutical pollutants like ciprofloxacin (CIP) and ibuprofen (IBU) are frequently detected in aquatic environments, posing risks to ecosystems and human health. Since pollutants rarely exist alone in the environment, understanding the thermal stability and degradation kinetics of these compounds, especially in mixtures, is crucial for developing effective removal strategies. This study therefore investigates the thermal stability and degradation kinetics of CIP and IBU, under different heating rates. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were employed to examine the thermal behavior of these compounds individually and in mixture (CIP + IBU) at heating rates of 10, 20, and 30 °C/min. The kinetics of thermal degradation were analyzed using both model-fitting (Coats–Redfern (CR)) and model-free (Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Friedman (FR)) methods. The results showed distinct degradation patterns, with CIP decomposing between 280 and 550 °C and IBU between 152 and 350 °C, while the mixture exhibited multistep decomposition in the 157–500 °C range. The CR model indicated first-order kinetics as a better fit for the degradation (except for IBU). Furthermore, CIP exhibits higher thermal stability and activation energy compared to IBU, with the KAS model yielding activation energies of 58.09 kJ/mol for CIP, 11.37 kJ/mol for IBU, and 41.09 kJ/mol for CIP + IBU mixture. The CIP + IBU mixture generally showed intermediate thermal properties, suggesting synergistic and antagonistic interactions between the compounds. Thermodynamic parameters (ΔH°, ΔG°, ΔS°) were calculated, revealing non-spontaneous, endothermic processes for all samples (except in the FWO method) with a decrease in molecular disorder and positive ΔG° values across all models and heating rates. The study found that higher heating rates led to less thermodynamically favorable conditions for degradation. These findings provide important information concerning the thermal behavior of these pharmaceutical pollutants, which can inform strategies for their removal from the environment and the development of more effective waste-treatment processes. Full article