Search Results (120)

This study investigates the effects of three solid waste powders—fly ash (FA), silica fume (SF), and phosphogypsum (P)—on the drying shrinkage behavior of metakaolin-based geopolymers. To systematically evaluate the performance and underlying mechanisms, a comprehensive experimental program was conducted, including compressive strength and elastic modulus testing, early-age and variable-humidity drying shrinkage monitoring, mercury intrusion porosimetry, and microcalorimetry analysis. Results demonstrate that all three materials effectively reduce drying shrinkage through distinct mechanisms. The incorporation of 30% FA optimized the capillary pore network and densified the matrix, achieving a peak compressive strength of 53.51 MPa and an elastic modulus of 9.23 GPa. SF exhibited a dose-dependent effect; at an optimal content of 7%, it enhanced compressive strength by 28.3% through its nucleation effect and micro-aggregate filling. However, excessive SF (9%) led to pore coarsening and increased shrinkage. Although P incorporation slightly reduced mechanical strength, it decreased cumulative porosity by up to 8% and formed needle-like Wairakite-Ca crystals that provided micro-structural support, resulting in a net shrinkage reduction of up to 137.83 µε. This study provides a scientific basis for designing low-shrinkage, low-carbon geopolymers by tailoring solid waste incorporation to engineer multiscale pore structures. Full article

Direct measurement of thermogenic heat production remains a major challenge in adipose biology. Isothermal microcalorimetry offers a label-free approach to quantify metabolic heat output, yet key parameters governing its application to adipose tissue remain poorly defined. Here, we systematically evaluate the use of the CalScreener isothermal microcalorimetry platform to quantify thermogenic heat production across multiple adipose models, including adipocyte spheroids, freshly isolated adipocytes, and intact adipose tissue explants. Heat production scaled with spheroid size within a defined range and increased linearly with spheroid number per well, demonstrating the quantitative sensitivity of the calorimetric measurements. Pharmacological modulation of mitochondrial respiration in cultured primary beige adipocytes demonstrated that oxidative phosphorylation is a major driver of the calorimetric heat signal, including heat generation associated with mitochondrial proton leak. Freshly isolated adipocytes and intact adipose tissue exhibited depot-specific thermogenic activity and retained responsiveness to β-adrenergic stimulation ex vivo. Across adipose depots, intact tissue explants revealed unexpected differences in thermogenic heat production that were not fully reflected by thermogenic gene expression, highlighting divergence between molecular and functional readouts. Intact adipose tissue maintained measurable thermogenic heat production following extended ex vivo handling in nutrient-containing medium, such that tissues collected across a prolonged harvest window exhibited comparable calorimetric activity, enabling batch analysis of large experimental cohorts. Microcalorimetry further resolved regional differences in thermogenic heat production within the inguinal adipose depot following cold exposure. Together, these findings define key experimental considerations for applying isothermal microcalorimetry to adipose biology and demonstrate its utility for directly quantifying thermogenic metabolism in cells and intact tissues. Full article

To address the challenges of rapid water loss and insufficient long-term inhibition efficiency of conventional inhibitors in the high-temperature environments of deep goafs, a novel, environmentally friendly Deep Eutectic Inhibitor (DEI) was synthesized. This DEI utilizes citric acid (Ca) and proline (Pr) as the hydrogen bond donor and acceptor, respectively, with ascorbic acid (VC) and propyl gallate (PG) serving as antioxidants. A moisture retention evaluation model based on Fick’s law of diffusion was established to systematically investigate the liquid-domain stability of the DEI across a temperature range of 30 °C to 120 °C. The results demonstrate that the DEI exhibits superior moisture retention capabilities under high-temperature conditions, with the relative moisture retention peaking in the 80–110 °C range. Mechanistically, the formation of a robust hydrogen bond network effectively counteracts moisture evaporation driven by thermal kinetic energy. Furthermore, the DEI demonstrated significant inhibition effects on four coal samples with varying degrees of metamorphism. Tests on oxidative heat release characteristics revealed that DEI treatment delayed the initial oxidation temperature of the coal. Kinetic analysis further indicated that during the critical oxidation stage (200–300 °C), the apparent activation energy of the treated coal samples increased by 10.28–18.9 kJ/mol, effectively suppressing the spontaneous combustion process. This study contributes to the development of high-efficiency and eco-friendly fire prevention materials for coal mines. Full article

The pursuit of sustainable alternatives has spurred interest in plant-derived bioherbicides with multi-target actions to combat resistance. This study explored the herbicidal potential of Agave lechuguilla extract (AGE) against the widely problematic weed Chenopodium album L. (lambsquarters). Various methods, including germination assays, biochemical profiling, measurements of antioxidant enzyme activity, isothermal microcalorimetry, and both macroscopic and microscopic morphological analyses, were employed to evaluate the effects of AGE relative to glyphosate (1.5%). The results indicated that AGE inhibited seed germination in a concentration-dependent manner, with the 30 g/L dose exhibiting the most significant effect. Treatment with 30 g/L of AGE led to a notable decrease in total carbohydrate content and catalase activity, an increase in total lipids, and an enhancement of glutathione reductase activity. Additionally, it suppressed metabolic heat output and severely disrupted root and cellular architecture, resulting in a reduction of cell area by 51.1%. In contrast, glyphosate primarily increased lipid content and induced near-complete metabolic suppression while causing distinct morphological and enzymatic alterations. The findings demonstrate that AGE functions as a multi-target pre-emergence bioherbicide, disrupting processes related to germination, metabolism, oxidative balance, and morphology through mechanisms that differ from the single-target action of glyphosate. This underscores its potential for sustainable weed management. Full article

Fe-oxyhydroxides can incorporate toxic metals during the formation of mineral phases in soils and sediments, thereby potentially altering the environmental reactivity of metals and impacting the microbial communities. In this study, isothermal microcalorimetry has been used to monitor the metabolic activity of Pseudomonas putida KT2440 exposed to pure ferrihydrite and to Pb-, Cd-, and As-bearing ferrihydrites under oxygen-limited conditions. Calorimetric measurements of the integral heat released during the exponential growth were combined with the analysis of dissolved iron and heavy metals, as well as the glucose uptake, to understand how heavy metal incorporation modifies mineral reactivity and microbial heat output. Pure ferrihydrite decreased the integral heat by about 45%, primarily due to glucose and phosphate depletion, Fe(III) leaching, and mineral–cell aggregation. Heavy metal dopants were found to modulate nutrient availability, surface charge, and Fe solubilization, which, in turn, influenced the integral heat. Pb-Fh generated the highest ferrihydrite dissolution and metabolic heat, with a maximum effect at intermediate substitution levels. As-Fh induced moderate Fe release and metabolic activity, consistent with the enhanced phosphate sorption and lowered surface charge. Cd-bearing Fh showed minimal reactivity and yielded the lowest heat output. Microcalorimetry was proven useful for unraveling microbe–mineral interactions in complex contaminated environments. Full article

The interaction between moisture and textile materials plays a critical role in transient thermal comfort, particularly through the exothermic heat released during wetting. While the heat of wetting has been extensively characterized at the fiber level, its behavior in finished fabrics, where structure, porosity, and air gaps influence moisture uptake, remains poorly understood. This study quantifies the heat of wetting of clothing fabrics using a TAM Air isothermal microcalorimeter under controlled isothermal conditions (23 °C). Five fabric types representing different fiber chemistries (Merino wool, cotton, viscose, and polyester) were evaluated in both folded and dissected forms to assess the influence of sampling methods. Wool fabrics exhibited the highest heat release, followed by viscose and cotton, whereas polyester showed negligible exothermic response due to its non-hygroscopic nature. Overall, fabric-level heat of wetting values were lower and more variable than the corresponding fiber-level values reported in the literature, reflecting the combined effects of fabric structure, air permeability, surface hydrophilicity, and sampling uniformity. These findings demonstrate the feasibility and limitations of isothermal microcalorimetry for characterizing moisture–fabric interactions and highlight the need for improved sampling and measurement protocols to more accurately capture fabric-level sorption heat relevant to clothing comfort. Full article

In the article we investigated the effectiveness of a synergistic system designed to reduce the fire hazard of flexible polyurethane (PUR) foams. The examined system consisted of a carbon-based filler graphene (G), carbon nanotubes (CNTs), or expanded graphite (EG) combined with melamine polyphosphate (MPP). The investigated polyurethane foams (PUR) were synthesized at room temperature via a polycondensation reaction between a polyol and an isocyanate, with an OH: NCO molar ratio of 2:1. Both the carbon fillers and melamine polyphosphate were homogeneously dispersed within the polyol component. Thermogravimetric analysis (TGA), cone calorimetry, and microcalorimetry were used to evaluate the influence of the fillers on the thermal stability and flammability of the PUR foams. The toxicity of the gaseous products was assessed using a coupled TG-gas analysis system, while the optical density of the evolved gases was determined using a Smoke Density Chamber (SDC). The obtained results demonstrated that the applied synergistic carbon-phosphorus filler system significantly reduced the fire hazard of the tested PUR foams. In particular, the EG5-MPP system enabled the formation of self-extinguishing materials. Full article

Histatins are histidine-rich antimicrobial peptides present in human saliva, with histatin 5 (Hst5) demonstrating the most potent antifungal activity. Previous studies have linked the antifungal properties of histatins, particularly those against Candida species, to their ability to bind metal ions such as Cu(II) and Zn(II). While the antimicrobial activity of some histatins is well established, the impact of metal ion coordination on this activity remains an area of ongoing investigation. This study focuses on histatin 8 (Hst8), a less-explored member of the histatin family, and compares its metal-binding and antimicrobial properties to those of Hst5. Using isothermal titration microcalorimetry (ITC), we examined the interactions of Hst8 with Cu(II), Zn(II), and Ni(II) ions and evaluated its antimicrobial activity against Escherichia coli, Staphylococcus aureus and two Candida albicans strains. Our findings revealed significant differences in copper and zinc binding between Hst5 and Hst8, with both peptides exhibiting distinct antifungal profiles. Interestingly, it has been shown that copper ions bind to Hst5 in a distinctly different manner than to Hst8. Hst5 exhibits two binding sites with dissociation constants (K_DITC) of 0.2 µM and 14.8 µM, whereas Hst8 has only one set of binding sites with a K_DITC of 12.3 µM. These results highlight the potential role of metal ion coordination in modulating the antimicrobial efficacy of histatins, providing further insight into their therapeutic potential. Full article

Meibum—a lipid-rich secretion produced by holocrine Meibomian glands (MG)—plays a central role in maintaining ocular surface homeostasis in humans. Previously, changes in MG lipidomes induced by inactivation of critical genes of meibogenesis, such as Elovl3, Soat1, Awat2, Sdr16c5/Sdr16c6, and others were shown to cause MG dysfunction (MGD) and dry eye in experimental animals. Here, we describe the impact of the changes in the lipid composition of meibum on its protective properties, specifically physiologically relevant thermotropic characteristics, using various mutant and wild-type animal models, and comparing them with healthy human subjects and patients with MGD. Meibum samples were analyzed using liquid chromatography/mass spectrometry (LC/MS) and differential scanning microcalorimetry (DSC). We found that any change in the balance between major lipid classes in meibum—wax esters, cholesteryl esters, triacylglycerols, and free cholesterol—cause detrimental changes in its thermotropic properties, loss of cohesiveness, and abnormal expressibility from MG, resulting in MGD-like phenotypes of the eyes and adnexa. We conclude that tested knockout mice can be valuable models for modeling and studying MGD. A combination of LC/MS and DSC can be a powerful diagnostic tool and may help to diagnose MGD and other pathologies, as well as determine their molecular mechanisms. Full article

Temperature is a key driver of microbial metabolism, yet non-invasive methods for quantifying microbially generated heat in complex environments remain limited. Here, we present a low-cost digital temperature sensing system integrated into an Arduino-controlled data acquisition setup to monitor microbial activity in stratified Winogradsky columns, which are self-contained sediment microcosms that reproduce natural oxygen and sulfide gradients. Localized temperature differences of up to 0.55 ± 0.04 °C were detected between aerobic and anaerobic layers, consistent with microbial heat generation in active sediment zones. Short-term insulation experiments further amplified these effects, demonstrating that microbial thermogenesis can serve as a reliable proxy for metabolic activity. Compared with infrared thermography or isothermal microcalorimetry, the proposed approach is simple, cost-effective, and compatible with aqueous and stratified systems. The method enables real-time, non-invasive observation of microbial metabolic dynamics and establishes a framework for continuous thermal monitoring in living environmental microcosms. Full article

Platycerium bifurcatum is one of the most widely cultivated ornamental fern species worldwide and a valuable component of the biodiversity of pantropical forests. In addition to its photosynthetic function, the sporotrophophyll leaves of this species periodically develop a large, clearly demarcated sporangium at the leaf tips, enabling physiological and biochemical measurements both in the active sporulation part and in the non-sporulating leaf area. The aim of this study was to assess anatomical changes, determine thermal effects and the content of selected phytohormones, and analyze the spatial distribution of pigments in the sporophilic and trophophylic part of the same leaf during spore formation. The study utilized fluorescence microscopy, isothermal microcalorimetry, Raman mapping, and ultra-high-performance liquid chromatography coupled with a Triple Quad LC/MS analyzer. The results revealed significant physiological differences between the sporulating and non-sporulating leaf areas. For the first time, differences in thermogenesis within the two leaf regions accompanying sporulation and linked to the sporangium development stage have been demonstrated in ferns. Increases in gibberellins (GA3, GA4, and GA6), auxin (indole-3-butyric acid), (±)-cis, trans-abscisic acid, and abscisic acid glucose ester were observed in the sporophilic part of the leaf, as well as fluctuations in phytohormones in the trophophilic part, indicating internal metabolite relocation within the leaf. Raman analysis and 2D mapping revealed local lignin accumulation and fluctuations in carotenoid levels during spore maturation. The results of this study demonstrate physiological variation within a single leaf and the mechanisms accompanying sporulation, which provide a better understanding of fern adaptive strategies. Full article

Commercial alumina and silica–alumina catalysts were investigated for propylene (PEN) production via an isopropanol (IPA) dehydration reaction between 200 and 300 °C at an atmospheric pressure and IPA partial pressure of 5136 Pa. The reaction conditions were chosen to fit with the further conversion of PEN into value-added compounds with minimal capital cost, and the conceptual process design was discussed. The textural properties, structure and chemical composition of as-received and hydrothermally treated catalysts were characterised by the adsorption–desorption of N₂, X-ray fluorescence, X-ray diffraction and Nuclear Magnetic Resonance spectroscopy. The adsorption microcalorimetry of NH₃ and SO₂ was used to determine the amount, strength and strength distribution of acid–base sites, while the nature of the acid sites was investigated by Fourier Transform Infraed spectroscopy. Surface area, pore-size distribution and pore volume were not determining factors for the catalytic performances of studied solids in the conditions used here. The best-performing catalyst combined stable textural properties and a high number of high-strength acid sites (Q_diff > 150 kJ/mol NH₃) under hydrothermal conditions. The importance of determining the number and strength of acid sites of water-aged catalysts, when considering reactions where water is present as reactive or product, is underlined. Full article

The complexation of nabumetone (NAB) and naproxen (NAP) with cucurbit[7]uril (CB7) was investigated in aqueous solution by isothermal titration microcalorimetry, mass spectrometry, NMR spectroscopy, and computation methods. High-resolution mass spectrometry was used for the determination of the binding stoichiometry and the gas-phase stability of the drug–CB7 complex. The doubly charged NH₄⁺ or Na⁺ adducts of the 1:1 complex were observed in the mass spectra. The dissociation of complexes was monitored at different collision energies, (1–16) eV, leading to the neutral loss of NH₃ and the drug, with charge retention observed on CB7. By performing ITC experiments, all the thermodynamic parameters were determined for the NAB-CB7 complex in water at 25 °C. The corresponding values amounted to the following: logK = 4.66 ± 0.01; Δ_rG° = −26.7 ± 0.1 kJ/mol; Δ_rH° = −20.2 ± 0.7 kJ/mol; TΔ_rS° = 6.4 ± 0.8 kJ/mol, i.e., the formation of the inclusion complex is enthalpy driven and has a favorable entropy. The inclusion phenomena were further confirmed by NMR spectroscopy (¹H, ROESY, and DOSY), suggesting the encapsulation of the naphthalene ring of both drugs inside the CB7 cavity. The results of the DFT calculations and the IGMH analysis were in accordance with the experimental ones, suggesting that van der Waals interactions play a major role in drug–CB7 complexation. Full article

Background/Objectives: Phosphodiesterase 5 (PDE5) inhibitors, sildenafil, vardenafil, and tadalafil, activate the cyclic guanosine monophosphate pathway resulting in vascular smooth muscle relaxation. They have been tested for a broad variety of conditions from cancer to Alzheimer’s disease with a positive impact. The known mechanism of action of these drugs could not explain such a plethora of effects. We studied the influence of PDE5 inhibitors on lipid bilayers as a possible application point of their action. Methods: To monitor the membrane changes induced by PDE5 inhibitors, the differential scanning microcalorimetry and the molecular dynamics simulation were used. Results: We found that sildenafil, vardenafil, and tadalafil change elastic properties of model membranes: PDE5 inhibitors disorder thin membranes and order thick membranes. Moreover, PDE inhibitors were able to induce lipid interdigitation. To address the biological aspect of the findings, we performed molecular dynamics on smooth muscle cell’s lipid raft treated with PDE5 inhibitors and revealed the increased density of the lipids. Furthermore, we showed that the lipid condensation in the PDE inhibitors presence increases nitric oxide permeability. Conclusions: The obtained results may be of biological relevance as lipid raft thickening might have an impact on membrane protein function. Moreover, improved nitric oxide flow through membrane may partially explain therapeutic action of these drugs. The presented results are useful for finding novel implications for PDE inhibitors. Full article

The thermochemical properties of three sulfur-containing furan derivatives, 2-furanmethanethiol, furfuryl methyl sulfide, and methyl 2-methyl-3-furyl disulfide, were investigated using experimental and theoretical methods. Standard molar enthalpies of combustion were determined by combustion calorimetry, while enthalpies of vaporization were obtained through Calvet microcalorimetry. These experimental results allowed for the calculation of standard molar enthalpies of formation in the gas phase at 298.15 K. Theoretical calculations using high-level quantum chemical methods (G3) were performed to complement the experimental data. A comparison between experimental and theoretical values revealed good agreement, validating the computational approach. This study enhances the understanding of the energetic properties of sulfur furan derivatives, contributing reliable thermochemical data to existing databases and aiding in the development of predictive models for related molecular systems. Full article