Search Results (206)

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

Superparamagnetic iron oxide nanoparticles (SPIONs) have gained significant attention for Magnetic Fluid Hyperthermia (MFH)-based cancer therapy. However, achieving high heating efficiency under a biologically safe Alternating Magnetic Field (AMF) remains a challenge. This study investigates the synthesis and optimization of SPIONs encapsulated in TPGS-stabilized PLGA nanoparticles (TPS-NPs) using a modified single emulsion solvent evaporation (M-SESE) method. The aim was to achieve efficient magnetic heating under biologically safe AMF conditions while maintaining biocompatibility and colloidal stability, making these magnetic nanoplatforms suitable for MFH-based cancer treatment. TPS-NPs were characterized using various techniques, including Dynamic Light Scattering (DLS), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), and Superconducting Quantum Interference Device (SQUID) magnetometry, to evaluate their hydrodynamic size (Dh), zeta potential (ζ), encapsulation efficiency, and superparamagnetic properties. Calorimetric MFH studies demonstrated superior heating efficiency, with Specific Absorption Rate (SAR) and Intrinsic Loss Power (ILP) values optimized at an AMF of 4.1 GAm⁻¹s⁻¹, remaining within Hergt’s biological safety limit (~5 GAm⁻¹s⁻¹). These findings suggest that SPION-encapsulated TPS-NPs exhibit enhanced heat induction, making them promising candidates for MFH-based cancer therapy. The study highlights their potential as multifunctional nanoplatforms for magnetic hyperthermia therapy, paving the way for clinical translation in oncology for advanced cancer treatment. Full article

Direct ink writing (DIW) is an attractive, extrusion-based, additive manufacturing method for fabricating scaffold structures with controlled porosity using custom composite inks. Polycaprolactone–bioactive glass (PCL-BG) inks have gained attention for bone applications, but optimizing the formulation and fabrication of PCL-BG-based inks for improved printability and desired mechano-biological properties remains a challenge. This study employs a two-step design to systematically evaluate the effect of three factors in terms of PCL-BG composite printability and mechano-biological properties: ink preparation (acetone or dichloromethane (DCM) as the solvent, and mechanical compounding), the extrusion temperature (90 °C, 110 °C, and 130 °C), and the BG content (0%, 10%, and 20% BG). Pure PCL was used as the control. Rheological, calorimetric, and thermo-gravimetric analyses were conducted before printing. Cylindrical scaffolds and solid wells were printed to evaluate the printability, mechanical properties, and cytocompatibility. The scaffold porosity and pore size were carefully examined. Mechanical tests demonstrated that composite formulations with added BG and higher printing temperatures increased the elastic modulus and yield strength. However, PCL-DCM-BG combinations exhibited increased brittleness with higher BG content. Despite concerns about the toxic solvent DCM, the cytocompatibility was comparable to pure PCL for all ink preparation methods. The results suggest that the interaction between the ink preparation solvent, the BG content, and the printing temperature is critical for material design and fabrication planning in bone tissue engineering applications, providing insights into optimizing PCL-BG composite ink formulations for 3D printing in bone tissue engineering. Full article

The objective of this study was to design an active packaging material based on a polyethylene terephthalate (PET)/polypropylene (PP) film modified with a pullulan coating enriched with 1, 5, and 10% of clove essential oil (CEO). The physical properties of modified PET/PP films, including opacity, UV, and light visible barrier properties, were evaluated, and calorimetric measurement of color (L*a*b*) was performed, followed by determination of their potential of antioxidant activity and antimicrobial properties against foodborne pathogenic bacteria (E. coli, S. Enteritidis, S. aureus and L. monocytogenes) were characterized. Additionally, the effectiveness of the active packaging in reducing pathogenic bacteria on spinach leaves was evaluated. The PET/PP film with a pullulan coating enriched with CEO did not affect their transparency. The incorporation of CEO improved the film’s UV and visible light barrier properties without causing noticeable color changes while also exhibiting good antioxidant and antimicrobial activity. Furthermore, the application of active packaging effectively inhibited the growth of pathogenic bacteria on spinach leaves, demonstrating its potential for food preservation. Full article

The analysis of the influence of microhotplate size on the convective heat exchange of gas sensors is presented. Usually, the role of convection in the heat exchange of gas sensors is not considered in thermal simulation models because of the complexity of the convection process. As a result, the contribution of this process to the overall heat loss of sensors remains without detailed analysis. We analyzed convection issues in two groups of gas sensors: semiconductor and thermocatalytic (calorimetric) sensors and, on the other hand, in the oxygen sensors of the thermomagnetic type. It is demonstrated that there is a critical size leading to the formation of convective heat exchange flow. Below this critical value, only thermal conductivity of ambient air, IR (infrared) radiation from the heated microhotplate surface, and thermal conductivity of the microhotplate-supporting elements should be considered as channels for heat dissipation by the microhotplate, and the contribution of free convection can be neglected. The expression for the critical size contains only fundamental constants of air, d_cr~$4·\sqrt[3]{\raisebox{1ex}{$\nu ·D$}\!\left/ \!\raisebox{-1ex}{$g$}\right.}$, where ν is the kinematic viscosity of air, D is the diffusion coefficient, and g is the acceleration of free fall, d_cr~0.5 cm. Therefore, if the size of the microhotplate d <<d_cr, the influence of convection heat exchange can be neglected. Similar results were obtained in the analysis of the behavior of thermal magnetic sensors of oxygen, which use paramagnetic properties of molecular oxygen for the determination of O₂ concentration. In this case, the critical size of the sensor is also of significance; if the size of the magnetic sensor is much below this value, the oxygen concentration value measured with such a device is independent of the orientation of the sensor element. The results of the simulation were compared with the measurement of heat loss in micromachined gas sensors. The optimal dimensions of the sensor microhotplate are given as a result of these simulations and measurements. Full article

Emollients are multifunctional, water-insoluble ingredients used in cosmetic products. This study aims to define the chemical and physical characteristics and test the activities of a new ester-based emollient, Sharofeel DS (DS), in comparison with other commonly used emollients (fatty alcohols, esters, and silicone emollients). The new entity was synthesized from naturally derived reactants and designed to be utilized in different cosmetic applications, such as skin care, hair care, and makeup. Methods: The emollient was characterized on the basis of its physical properties (Ultraviolet/Infrared (UV/IR) analysis, density, dynamic viscosity, refractive index, surface tension, and contact angle), calorimetric properties by thermogravimetric analysis (TGA) and differential scanning calorimetry analysis (DSC), viscoelastic properties as is and in emulsion, and toxicity tests. According to the results obtained, DS demonstrated density (0.881 g/mL) and viscosity (86 cPs) values comparable to fatty alcohol emollients, with a refractive index (1.457) comparable to fatty alcohol and ester-based emollients and a surface tension (22.53 mN/m ± 0.11 mN/m) similar to the ester-based ones. It proved stable below 308 °C and capable of reducing the loss of internal water from hair strands (−7.5% w/w). Lastly, the toxicity tests proved that DS is safe for topical skincare, haircare, and makeup applications. Full article

The increasing quest for greener and more sustainable polymeric materials has gained interest in the past few decades. Non-isocyanate polyurethanes (NIPUs) have attracted attention considering that they are produced through less toxic methods compared to the conventional polyurethanes (PUs) obtained from petroleum resources and toxic isocyanates. In this context, adipic acid, glycerol carbonate, 1,2-ethylenediamine, and 1,6-hexamethylenediamine, were used to synthesize NIPU_ethyl and NIPU_hexa, respectively. The obtained NIPUs were characterized using nuclear magnetic resonance spectroscopy (H-NMR spectra) and Fourier-transform infrared spectroscopy (FTIR) analysis, which verified the structures of the intermediate and final products. Calorimetric and dielectric studies provided direct and indirect support for the facilitated thermal stability of NIPU_ethyl and NIPU_hexa. Compared to the intermediate product, the NIPUs exhibit elevated glass transition temperatures, suggesting the formation of more rigid structures. The NIPUs were also tested in terms of swelling properties, and the results indicated that NIPU_hexa absorbs and withholds increased amounts of water for longer time periods compared to NIPU_ethyl, and their hydrolysis and enzymatic hydrolysis confirmed that NIPU_hexa is more stable in aqueous environments than NIPU_ethyl. Therefore, the successful production of adipic-acid-based NIPUs through a novel perspective of the polyaddition path is reported and complemented by the characterization of the obtained materials with several techniques. Full article

Cotton biomass residues consist of an important portion of the agricultural byproducts. In this work, we systematically analyzed and compared the morphology and thermal properties of nine cotton biomass byproducts. The unique tubular and/or porous morphology of some samples (e.g., main stems, branch stems, and petioles) implied their structural advantage in the development of electric supercapacitors and pollutant absorbents. The higher heating values of the nine samples ranged between 17 and 20 MJ kg⁻¹, higher than some of the other common agricultural byproducts (e.g., rice husk and sugarcane bagasse). The moisture content showed a positive correlation (p > 0.05) to the dehydration temperature of the differential scanning calorimetric plots. The residual char after thermogravimetric analysis could be separated into a high-yield cluster (34.4–26.6%) of leaf blades, bracts/peduncles, burrs, defatted meal, and petioles, and a low-yield cluster (20.5–13.6%) of main stems, branch stems, cotton gin waste, and cottonseed hull. These observations and data are useful for a better understanding of the fundamental chemistry of cotton biomass byproducts. Growing knowledge is useful for improving their recycling strategies and may shed light on the exploration of new value-added products or applications from these cotton biomass byproducts for a circular economy with sustainable agriculture. Full article

Understanding triacylglycerol (TAG) metabolism is crucial for developing algae as a source of biodiesel. TAGs are the main reservoir of energy in most eukaryotes. The final, rate-limiting step in the formation of TAGs is catalyzed by 1,2-diacylglycerol acyltransferases (DGATs). In the green alga Chlamydomonas reinhardtii, DGAT3 is phylogenetically related to plant DGAT3 but unrelated to other DGATs from eukaryotes, such as DGAT1 and DGAT2. In this study, we described the conformational preferences and the lipid-binding features of the DGAT3 from C. reinhardtii. To characterize its conformational stability and structural features, we used several biophysical probes, namely, fluorescence, circular dichroism (CD), and differential scanning calorimetry (DSC). Our results showed that the protein was mainly disordered, containing a small population of folded conformations in a narrow pH range (pH 8 to 10). The conformational stability of the folded structure of DGAT3 was very low, as shown by urea or guanidinium denaturations. Thermal denaturation, followed by fluorescence or CD, as well as calorimetric denaturation, followed by DSC, did not yield any transition in the pH range where DGAT3 acquired a “native-like” conformation. Furthermore, we used two approaches to demonstrate the interaction of DGAT3 with lipid membranes at the pH at which it had acquired a “native-like” conformation. The first involved the measurement of anisotropy and fluorescence quenching of the protein. The second approach focused on examining possible modifications of the biophysical properties of lipids due to their interaction with DGAT3, through anisotropy measurements and leakage assays. Both methods produced consistent results, suggesting that DGAT3 preferentially interacted with negatively charged membranes. These results will allow the design of a more efficient and stable DGAT3, as well as an in-depth understanding of how the metabolism of TAGs is accomplished in C. reinhardtii. Full article

An extensive thermochemical study of γ-undecanolactone and δ-undecanolactone has been developed using two complementary calorimetric techniques. The combustion energy of each compound was determined by static-bomb combustion calorimetry, and the corresponding enthalpy of vaporization was determined by high-temperature Calvet microcalorimetry, in which both properties of each compound are reported at T = 298.15 K. The standard molar enthalpy of formation in the gas phase of each lactone was derived by the combination of the experimental results. Additionally, high-level computational calculations were carried out, using composite ab initio G4 and G4(MP2) methods, as well as DFT M06-2X/6-311++G(d,p) approach, to estimate the corresponding enthalpy of formation in the gas phase. The experimental and computational results are in good agreement. The G4 and G4(MP2) methods show the best accordance with experimentally determined gas phase enthalpies of formation. The experimental results are discussed in terms of structural contributions to the energetic properties of the lactones studied, as well as to other alkylated γ- and δ-lactones, and empirical correlations are suggested for the estimation of the standard molar enthalpies of formation, at T = 298.15 K, for other alkylated γ- and δ-lactones, both in the liquid and gaseous phases, as well as for the respective enthalpies of vaporization. Finally, the thermochemistry of individual steps of lactone ring opening and successive decarboxylation mechanism, including the identification of transition states, was studied using the M06-2X/6-311++G(d,p) approach. Full article

This article presents an overview of airflow velocity measurement methods applied to renewable energy. Basic measurement methods used in this field are discussed: tachometric, ultrasonic, and calorimetric anemometry. The principle of operation and basic properties of anemometers are presented, and based on publications from the last decade, a systematic review of development directions and trends in this field is made. The aim of the article is to familiarize people dealing with renewable energy problems, in particular wind energy, with the current state of knowledge in the field of anemometric measurements, properties of individual types of measuring devices, as well as directions of development of measurement tools. This will allow for the optimization of processes in the field of wind energy, in particular in the selection of the location of the energy facility, implementation of investments and control, diagnostics, and monitoring during operation. The selection of metrological tools adequate to the problem also allows for ensuring an appropriate level of work safety and environmental and ecological harmony and supporting the process of sustainable development. Full article

Non-ionic surfactants are an important solvent in the field of green chemistry with tremendous application potential. Understanding their phase properties in bulk or in confined environments is of high commercial value. In recent years, the combination of molecular dynamics (MD) simulations with multinuclear solid-state NMR spectroscopy and calorimetric techniques has evolved into the most powerful tool for their investigation. Showing recent examples from our groups, the present review demonstrates the power and versatility of this approach, which can handle both small model-surfactants like octanol and large technical surfactants like technical polyethylene glycol (PEG) mixtures and reveals otherwise unobtainable knowledge about their phase behavior and the underlying molecular arrangements. Full article

This study investigates the effect of ultrasonic-assisted preparation on the structural and physicochemical properties of water caltrop starch-palmitic acid complexes as a function of ultrasound intensity and treatment time. All samples exhibited the characteristic birefringence of starch-lipid complexes under the polarized microscope, and flake-like and irregular structure under scanning electron microscope (SEM), indicating the formation of complexes through ultrasonic-assisted preparation. X-ray diffraction pattern further confirmed the transition from the original A-type structure for native starch to V-type structure for starch-lipid complexes, and the relative crystallinity of starch-lipid complexes increased as the ultrasound intensity and treatment time increased. Attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR) analysis indicated a decreasing trend in absorbance ratio at wavenumber of 1022 cm⁻¹/995 cm⁻¹, suggesting that the increase in the complex promoted the self-assembly within the short-range ordered structure, leading to the formation of bonds between the complexes. However, rapid-visco analysis (RVA) demonstrated that the viscosity generally decreased as the ultrasound intensity and treatment time increased, possibly due to the reduction in molecular weight by ultrasound. Differential scanning calorimetric (DSC) analysis revealed that the control starch-lipid complex without ultrasound treatment (US-0-0) exhibited two distinct endothermic peaks above 90 °C, representing Type I (95–105 °C) and Type II (110–120 °C) V-type complexes. However, ultrasound-treated samples showed only one peak around 95–105 °C and increased enthalpy (∆H), which was likely due to the breakdown of amylose and amylopectin, leading to more complex formation with palmitic acid, while the resulting shorter chains in the ultrasound-modified sample favor the formation of Type I complexes. Full article

Objective: Peripheral artery disease (PAD) is a prevalent vascular condition characterized by arterial narrowing, which impairs blood flow and manifests as intermittent claudication, a pain or cramping sensation induced by physical activity or ambulation. Walking distance is a crucial clinical indicator of peripheral artery disease, and it correlates with the disease severity and risk of mortality. It reflects the severity of the disease, with reduced mobility indicating an increased risk of morbidity. It can also inform on the efficacy of the treatment. Cilostazol, a phosphodiesterase III inhibitor, has been demonstrated to enhance walking distance in patients with peripheral artery disease through the dilation of blood vessels and the inhibition of platelet aggregation. With this preliminary study, we aimed to elucidate other possible effects of cilostazol, specifically its influence on the structural properties of red blood cells. Methods: 10 patients (5 men, 5 women) with PAD were treated with cilostazol over a three-month period. Its biochemical effects on RBCs were determined using differential scanning calorimetry (DSC). Patient’s blood samples were collected at the start of treatment, then after two weeks, one month, two months, and three months of therapy. Results: The DSC analysis revealed shifts in thermal properties, including change in peak (melting or denaturation) temperature (T_p) and calorimetric enthalpy (ΔH_cal), which indicate significant structural changes in red blood cells. These thermal property changes correlated with clinical improvements in walking distance reported by patients. Conclusions: Our findings suggest that cilostazol induces substantial biochemical modifications in red blood cells, enhancing their functional properties and contributing to improved clinical outcomes. This study highlights the potential of differential scanning calorimetry as an adjunctive method for assessing the effectiveness of treatments for peripheral artery disease at the cellular level. However, further investigation with larger patient cohorts is required to confirm these initial results. Full article

The full potential of glauconite-based nanocomposites as micronutrient fertilizers remains underexplored, particularly their interaction with Zn, Cu, and B. Despite the promising applications, the mechanisms of nutrient sorption and their effects on plant growth require further investigation, especially concerning structural changes and nutrient delivery efficiency. This study investigates the modification of glauconite with Zn, Cu, and B solutions to create multifunctional nanocomposites with enhanced properties. It was established that the activation process preserves the primary globular–lamellar morphology of glauconite while introducing structural changes. Nanocomposites were synthesized using chemical activation and characterized using XRD, SEM-EDS, TEM, FTIR, and BET analyses. Agrochemical tests evaluated their effects on oat growth under controlled conditions. Nanocomposites with zinc sulfate exhibited an increase in specific surface area and mesoporosity, enhancing sorption capacity and facilitating the formation of inner-sphere complexes on the mineral’s basal surface. Modification with copper led to the formation of secondary phases, such as sulfates, on the surfaces of microflakes and globules while preserving the crystalline structure with inner-sphere coordination of Cu²⁺. Boron-modified nanocomposites were characterized by localized restructuring, pore channeling, and an increase in mesopore diameter, along with the formation of outer-sphere complexes relative to the basal surface of glauconite. Thermogravimetric and calorimetric analyses with mass spectrometry revealed specific endothermic and exothermic effects, particularly in Zn-modified samples, confirming changes in dehydration energetics. Agricultural tests on oats (Avena sativa) demonstrated the effectiveness of Cu- and B-modified nanocomposites in improving plant growth parameters, including a 7% increase in plant height and a 6.4% increase in dry weight. Zn-modified nanocomposites showed high germination rates (up to 100%) at low dosages but require optimization to avoid phytotoxicity at higher concentrations. The findings highlight the potential of adapting nanocomposites for targeted nutrient release. Additionally, glauconite nanocomposites have potential applications in restoring degraded soils, treating polluted runoff, and developing slow-release agrochemical systems. Full article