Search Results (222)

The aim of the article was to analyze the potential simultaneous use of magnetic nanoparticles as contrast agents in MRI imaging and for magnetic hyperthermia. The study proposed characterizing the nanoparticles using various measurement methods in order to investigate the relationships between different properties. The first stage involved measuring images of nanoparticle samples using scanning transmission electron microscopy (TEM) and dynamic light scattering (DLS). The diameter distribution of nanoparticles was determined based on image segmentation. The next step involved measuring relaxation properties of nanoparticles in low and high magnetic fields. The research was carried out for nanoparticle solutions of various concentrations and properties. The last step was measuring calorimetric properties of nanoparticles as a thermal source under alternating magnetic field excitation conditions. The range of nanoparticle diameters (20–25 nm) for which maximum losses occur in an alternating magnetic field corresponds to the diameter range in which the maximum r₂ relaxivity is observed. Full article

Background: China’s rapidly aging population demonstrates the importance of conducting an accurate resting metabolic rate (RMR, kcal/day) assessment to mitigate geriatric nutritional imbalances—amid concurrent undernutrition (e.g., ~1/3 with protein insufficiency) and overnutrition (e.g., high obesity and type 2 diabetes rates). While RMR prediction equations exist for other populations, none are specific to Chinese older adults. This study aimed to develop and validate population-specific RMR prediction equations for community-dwelling Chinese older adults. Methods: A total of 189 healthy participants (Aged 69.5 ± 6.3, range: 60–94 years; BMI: 24.0 ± 3.1 kg/m²) were recruited from the Shanghai, China, community. RMR was measured via indirect calorimetry, and body composition via dual-energy X-ray absorptiometry. Results: Two novel prediction equations were derived: Cai1 (fat-free mass [FFM] + age): RMR = 1393.019 − (11.112 × age) + (11.963 × FFM); R² = 0.572, and Cai2 (sex + age + weight [WT]): RMR = 1537.513 + (91.038 × sex) − (11.515 × age) + (5.436 × WT); R² = 0.528. Both novel prediction equations achieved 82.5% adequacy (predicted RMR within 90–110% of measured values), minimal systematic bias (%) (−0.72% and −1.08%) and strong positive correlations with measured RMR (r = 0.792 and 0.773, both p < 0.001). Bland–Altman analysis confirmed no systematic bias. In contrast, 11 widely used published prediction equations (e.g., Harris–Benedict, Mifflin–St. Jeor) exhibited significant overestimation (systematic bias +8.39% to +38.03%). Conclusion: The novel population-specific RMR equations outperform published ones, providing a clinically reliable tool for individualized energy prescription in nutritional interventions to support healthy aging in Chinese older adults. Full article

Since there is limited information available in the literature about the thermodynamic properties of the Cu-Mg-Ti system, this work aims to determine the mixing enthalpy change for several liquid alloys from this system. To achieve the intended purpose, the applied methods were divided into two stages. The first one covered a high-temperature calorimetric measurement of the enthalpy of mixing performed at 1123–1402 K for liquid solutions in six measurement series (A–F). The obtained experimental results indicate that the liquid solutions are characterized by negative deviations from ideal solutions across the whole measured concentration range. The second stage of the study includes thermodynamic modeling. At first, based on the calorimetrically obtained experimental data and thermodynamic properties of the binary systems described by the Redlich–Kister model, a set of ternary optimized parameters for the Cu-Mg-Ti system were calculated. Then, for the calculation of the mixing enthalpy change, two models were used—the symmetrical Muggianu model and the asymmetrical Toop model. This study complements the information available in the literature and the obtained results aim to fill the gap in the current knowledge on thermodynamic properties. Full article

This paper presents the modification and experimental validation of a mathematical model for a single junction thermal voltage converter (SJTC) designed for high-precision alternating current (AC) voltage transfer. The original model is severely constrained by two main issues: (1) computational instability above 50 MHz due to the limitations of the housing impedance approximation, and (2) insufficient accuracy above 1 MHz due to the neglect of high-frequency skin effect and magnetic core effects in the Dumet wire leads. Significant refinements are subsequently implemented to extend the calculable frequency range of the standard from 1 to 100 MHz. This required re-evaluation of the Dumet wire leads’ frequency-dependent resistance and inductance using finite element method (FEM) simulations, which accounted for the skin effect and the magnetic permeability of the FeNi42 core. Additionally, the housing impedance calculation is stabilized using a formulation based on scaled modified Bessel functions, and the electrical conductivity of the input N-type connector pin is explicitly modeled. The improved model is validated against a reference calorimetric thermal voltage converter (CTVC) using 3 and 5 V nominal voltage standards. The results indicated excellent agreement between the calculated and measured AC-direct current (DC) transfer differences up to 10 MHz. In the extended frequency regime, the model correctly predicted the transition to negative transfer differences observed above 2 MHz for the 5 V standard. The largest discrepancies between the measured and calculated values occurred at 100 MHz. The measured transfer difference reached −15,090 (µV/V) with an expanded uncertainty (k = 2) of 190 (µV/V), whereas the calculated value is −12,500 (µV/V) with an expanded uncertainty of 3900 (µV/V). Although the deviation between the model and measurement increased above 30 MHz, the results remained consistent within the expanded measurement uncertainties across the entire 10 kHz to 100 MHz range, demonstrating the model’s suitability for providing traceability in high-frequency voltage metrology. Full article

The physico-chemical and electrophysical properties of carbon coke obtained by coking composite mixtures of pitches isolated from coal tar coking plants of JSC “Shubarkol Komir” and “Qarmet” are investigated. The component composition of the initial resins and the obtained pitches was determined by gas–liquid chromatography methods. The purpose of this study was to identify the patterns of influence of the composition of composite mixtures of pitches isolated from coal tar coking plants of JSC “Shubarkol Komir” and “Qarmet”, as well as heat treatment parameters (temperature 800–1000 °C, duration 4–6 h), on the thermophysical and electrophysical properties of electrode coke, with the determination of optimal conditions for obtaining a material combining low ash content and high carbon content. It was found that the content of phenols and paraffins in the resin of “Shubarkol Komir” is approximately 25% of each component. It is shown that the properties of the final coke depend on the ratio of the mixed pitches (1:1, 1:2, 2:1) and coking conditions (temperature 800–1000 °C, duration 4–6 h). Optimal characteristics (minimal ash content of 0.4%, maximal carbon content of 97.75%) were achieved with a pitch ratio of 1:2 and a temperature of 1000 °C for 6 h. A specific heat capacity in the range of 298–448 K was measured calorimetrically for this sample, where a type II phase transition was detected at 373 K. Electrophysical measurements in the range of 293–483 K revealed a complex temperature dependence of the resistance characteristic of a semiconductor with two sections of a narrow band gap (~0.67 eV and ~0.55 eV). The novelty of the work consists in a comprehensive study of composite mixtures of coal tar pitches and the influence of heat treatment parameters on the formation of thermophysical and electrophysical properties of electrode coke. For the first time, signs of a type II phase transition have been identified for this type of coke material and gigantic permittivity values (up to 10⁹) have been recorded, indicating its potential as a functional carbon material. Full article

Background: Cancer therapeutics development has been a challenge in medical and scientific areas due to their toxicity, limited biocompatibility, and unfortunate side effects. However, despite advances in early detection and the study of novel treatments, the mortality rate for breast cancer remains high, making it a significant global health concern. Objectives: In this study, poly(methyl methacrylate) (PMMA) nanoparticles functionalized with acrylic acid (AA), fumaramide (FA), and curcumin (CUR) as chelating and inhibitor agents were synthesized by emulsion polymerization techniques. Methods and Results: Comprehensive physiochemical characterization studies based on gravimetry, dynamic light scattering (DLS), electrophoresis, Fourier transform infrared (FT-IR), ultraviolet–visible (UV–Vis) and photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) revealed a pH dependence of nanoparticles that exhibit structural changes upon interaction with calcium (Ca²⁺) and magnesium (Mg²⁺) ions. Calorimetric thermodynamic properties measured by isothermal titration calorimetry (ITC) confirmed chelating coordination and positive cooperativity between the nanoparticles and metal ions. In vitro studies showed the low cytotoxicity of nanoparticles by fibroblast proliferation, and their chelation process was observed by fluorescence microscopy, with the loss of interaction between cells. Conclusions: These results suggest that the functionalized nanoparticles have potential in drug delivery systems (DDS) for targeted breast cancer therapies, providing a promising polymer material for more efficient and less toxic treatments. Full article

This paper presents a study of the thermal and rheological properties of isosorbide, showing that its degradation temperature (around 100 °C) is much lower than values previously proposed in the literature. Furthermore, remarkable calorimetric and viscoelastic behaviors, with features usually observed in semi-crystalline systems are presented. The onset of the melting is measured at 45 °C, while a glass transition occurs at −45 °C, followed by cold crystallization. Wide-angle X-ray diffraction confirmed the coexistence of crystalline domains and an amorphous fraction, which behaves as a molecular glass, with an estimated crystallinity of approximately 70%. Thermogravimetric analyses conducted under both air and nitrogen and at multiple heating rates, in line with ICTAC recommendations, established the robustness of the 100 °C degradation onset. These findings provide new structure–property relationships for isosorbide and open up new avenues for further research and development in this area. Full article

The calorific value of coal is a key parameter for pricing, trade, and combustion management. Conventional bomb calorimetry provides accurate results but is time-consuming, labor-intensive, and destructive. Near-infrared (NIR) spectroscopy offers a rapid and non-destructive alternative, yet its application is limited by strong band correlations, nonlinear spectral responses, and the lack of interpretability in many predictive models. In this study, the Kolmogorov–Arnold Network (KAN) is applied to the prediction of coal calorific value, demonstrating its capability to describe nonlinear spectral relationships within an interpretable mathematical structure. Based on this framework, a Radial Basis Function KAN (RBF-KAN) is further developed by replacing the B-spline bases in the KAN with radial basis functions, allowing improved representation of localized and irregular spectral variations while maintaining model transparency. Using 671 coal-powder samples measured by a portable MicroNIR spectrometer, the RBF-KAN achieved an RMSE of 1.35 MJ/kg and an MAE of 0.92 MJ/kg under five-fold cross-validation, outperforming conventional regression models, deep neural networks, and other KAN variants. Analysis of RBF activations and spectral attribution maps indicates that the model consistently responds to characteristic O-H and C-H overtone regions, which correspond to known absorption features in coal. These results suggest that the RBF-KAN provides a practical and interpretable framework for on-site estimation of coal calorific value, complementing traditional calorimetric analysis. Full article

This work presents a bespoke, non-contact, and low-cost Phosphor Thermometry (PT) technique for the measurement of material absorptivity. The approach circumvents the challenges associated with traditional and intrusive calorimetric techniques, which require secure contact with the sample substrate. A thermographic phosphor (TP), Manganese-activated Magnesium Fluorogermanate (MFG), was used as a two-colour thermometer utilising the peak intensity ratio technique, enabling an empirical temperature measurement of a given Material Under Test (MUT). The system was calibrated to temperature across a dynamic range of $20$°C to $140$°C and subsequently assessed in terms of noise and relative sensitivity. A mathematical model describing the thermal behaviour of the samples was subsequently developed and used to infer the absorptivity value of the MUTs. Two paints, Black 3.0^® and Avian-B500^®, with known but contrasting absorptivities, were analysed, resulting in measured absorptivity values of $0.9385$ and $0.0651$ within a range of $0.0081$ and $0.0127$ for the two paints, respectively. Subsequent mixtures of both paints, with inherent unknown absorptivities, provided resolvable and incremental steps between the two extremities. Further measurements at specific narrow-band wavelengths of $600$nm and $1550$nm of Black 3.0^® were performed, yielding median absorptivity values of $0.9598$ and $0.9172$ within a range of $0.0168$ and $0.0396$, respectively, therefore demonstrating the technique for the measurement of material absorptivity at discrete wavelengths. The potential of a non-contact calorimetric PT technique could provide a scalable, non-intrusive, and low-cost solution for measuring the wavelength-dependent absorptivity values of materials that are used across engineering and research fields. Full article

The heat generation of lithium-ion batteries is a critical parameter, as it significantly affects cell temperature. Poor thermal management can lead to elevated cell temperatures, accelerating side reactions, reducing cell lifetime, and, in extreme cases, causing thermal runaway. Therefore, understanding heat generation is crucial for the commercialization of emerging battery materials. Due to its high energy density, lithium–nickel–manganese–oxide (LNMO) is an attractive candidate for next-generation cathode materials; however, the composition of its heat generation is not yet fully understood. To address this, the state-of-charge (SoC)-dependent entropy coefficient and resistance of disordered LNMO cathodes are determined using the potentiometric method. The results show that both values are strongly influenced by the redox reactions of Ni and Mn. The entropy coefficient varies between 5.2 and −32.4 J ${\mathrm{mol}}^{-1}{\mathrm{K}}^{-1}$, depending on the SoC. Furthermore, the resistance exhibits a switching dependence on kinetics and mass transfer. The resulting heat flux calculations indicate that, at SoC < 20%, heat generation is dominated by the kinetic behavior of LNMO, leading to two exothermal peaks during discharge and one exothermal peak during charge. This behavior is validated through a comparison with a low-current calorimetric measurement. Full article

Alloys from the Ag-Ti system are extremely promising and offer the possibility of versatile applications owing to their attractive properties. However, due to the experimental difficulties caused, among others, by the significant difference in melting points of the components, most of the information on the thermodynamic properties available in the literature has been obtained by computer methods. Therefore, the main aim of this work is to extend the current knowledge about the experimentally determined thermodynamic properties of selected alloys from the Ag-Ti system. Within the scope of this work, calorimetric studies were carried out using Differential Scanning Calorimetry (DSC) and high-temperature drop calorimetry measurements. The first of the aforementioned methods was used to determine the characteristic temperature of the Ag_0.43Ti_0.57 alloy synthesized by mechanical alloying. Using titanium hydride instead of titanium for the preparation of alloys from the Ag-Ti system has not yet been reported in the literature. This paper presents a complete structural characterization (SEM, XRD studies) of the above alloy produced by this method. The second technique was applied to ascertain the mixing enthalpy change in the alloys in the composition range between x_Ti = 0.02–0.226, and for the measurements of the formation enthalpy of the AgTi intermetallic phase. Based on the calorimetric results obtained in this study, along with the relevant thermodynamic data from the literature, the Ag-Ti phase diagram was reoptimized. Full article

Blocking the MAPK pathway is a strategy to stop cancer cells proliferation. Despite all the successes, the acquisition of drug resistance by cells, as well as the mutational status of the downstream protein KRAS, reduces the tumor response to therapy. Ribonuclease binase from Bacillus pumilus is among the agents that block this pathway through direct interaction with EGFR and RAS. The present study is aimed at the design, optimization, and characterization of a novel complex based on antitumor binase immobilized on microgranular clinoptilolite-containing rock to ensure its prolonged release in the gastrointestinal tract. A set of modern methods including transmission electron microscopy, scanning electron microscopy, and computed tomography was used to characterize the granularity, porosity and elemental composition of the carrier. The size of binase particles, measured by atomic force microscopy at 7 nm, allows enzyme penetration into meso- and macropores of the carrier. Calorimetric results confirm that binase is stable at high temperatures, even exceeding those in the body, and retains catalytic activity in the model fluids of the gastrointestinal tract. The parameters for processing a natural clinoptilolite-containing rock and the conditions for binase sorption were selected. The gradual release of the enzyme from the carrier lasts over 20 h, which provides cytotoxicity towards human adenocarcinoma cells during movement through the gastrointestinal tract. Thus, for the first time a promising long-acting complex with antitumor and detoxifying properties was successfully created. Full article

The global energy crisis demands efficient electricity production solutions, especially for isolated communities where hydraulic energy can be harnessed sustainably. This paper presents a case study analyzing the efficiency of a 13,330 kW hydrogenerator, consisting of a bulb-type hydro-aggregate using the calorimetric method—a viable alternative when testing at nominal load is not feasible due to technical limitations. The method involves measuring the thermal energy absorbed by the cooling water under three operating conditions: no-load unexcited, no-load excited, and symmetric three-phase short-circuit. Measurements followed IEC standards and were conducted with high-precision instruments for temperature, flow, voltage, and current. The results quantify mechanical, ventilation, iron, and copper losses, as well as additional losses via radiation and convection. Thermal analysis revealed significant heat accumulation in the rotor and stator windings, indicating the need for improved cooling solutions. The calorimetric method enables efficiency evaluation without interrupting generator operation, offering a valuable tool for diagnostics, predictive maintenance, and informed decisions on modernization. Furthermore, integrating an intelligent operational control system could enhance efficiency and improve the quality of the supplied energy, supporting long-term sustainability in hydroelectric power generation. Full article

The ${\gamma }^{\prime }$-Fe₄N system has a high technological relevance due to its multiple applications in the field of surface treatment against wear and corrosion of iron in steel parts, as well as in the manufacturing of high-density magnetic recording devices, and so on. In the present work, we present a wide research of the structural, elastic, magnetic, vibrational, and thermophysical properties by means of the phonon analysis. For these purposes, we have compared theoretical and experimental results. The theoretical data were obtained by employing ab initio electronic structure calculations in the framework of density functional theory (DFT), and different experimental measurements, such as X-ray diffraction, magnetization measurements, and calorimetric techniques, were used to characterize the ${\gamma }^{\prime }$-Fe₄N system. The resulting comparison showed an excellent agreement between the theoretical and experimental data reported. Full article

We present an alternative to the classical SQUID magnetometric measurements for the First-Order Reversal Curve (FORC) diagram approach by employing differential scanning calorimetry (DSC) experiments. After discussing the main results, the advantages and limitations of the magnetometric FORCs, we introduce the calorimetric method. We argue that, while the results are comparable to those obtained via magnetometry, the calorimetric method not only significantly simplifies the required mathematical computations but also detects subtle or overlapping phase transitions that might be hard to distinguish magnetically. The methodology is illustrated through both experimental data and mean-field simulations. Full article