Differential Thermal Analysis Research Articles

Anti-pathogenic and probiotic-friendly effect of benzyloxy pyridine derivative impregnated into bacterial cellulose matrix

Bacterial cellulose (BC) has emerged as a promising biomaterial for biomedical applications due to its unique properties. In this study, firstly, the potential of BC as a carrier material for the originally synthesized benzyloxy pyridine derivative (BeOxP), and also an antimicrobial and probiotic bacteria-friendly (on Lactiplantibacillus plantarum 299v (LP299V®) (DSM 9843)) effect of BC- BeOxP was investigated. The BC- BeOxP composite material was developed using a simple and efficient method, ensuring the uniform dispersion of BeOxP within the BC matrix. Characterization of BeOxP has been carried out with High-Resolution Mass Spectroscopy (HRMS) and Nuclear Magnetic Resonance (NMR). Additionally, BC- BeOxP was characterized by Thermogravimetric analysis (TGA), Differential thermal analysis (DTA), Scanning Electron Microscopy (SEM), Texture analysis, and Fourier-transform infrared spectroscopy (FTIR), confirming the successful integration of BeOxP without compromising the structural integrity of BC. The mechanical properties of the BC- BeOxP composites were also evaluated to ensure their suitability for drug-carrying or food-packaging applications. Antimicrobial activity of the BC- BeOxP was analyzed against Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922 while the probiotic-friendly effect was tested on Lactiplantibacillus plantarum 299v (LP299V®) (DSM 9843). The findings open avenues for further research of BC-based drug carriers or packaging materials for advanced biomedical applications.

Biochar Regulates the Humification of Kitchen Waste and the Effects of the Humic Acid Structure of Products on Black Soil

Kitchen waste is a misplaced resource that is characterized by a high organic matter content, high water content, and a tendency to rot easily. Biochar is a black solid substance produced under high-temperature, anaerobic conditions using agricultural organic wastes as the raw material. It possesses a large specific surface area, a loose and porous structure, and functional groups, which confer high thermal stability and strong adsorption capabilities. However, little is known about how humic products made from biochar affect the composition and structure of soil humus. To solve the above problems, this study carried out a two-year outdoor field experiment by means of element analysis, infrared spectroscopy, and differential thermal analysis (0.4 kg/m2 (W4), 0.8 kg/m2 (W8), 1.2 kg/m2 (W12), 1.6 kg/m2 (W16), and 2.0 kg/m2 (W20)); CK was the blank control (no application). The samples were collected one year and two years after they returned to the field. The results showed that the application of organic materials facilitated the accumulation of soil organic carbon (SOC) and increased the total nitrogen (TN) content. The highest SOC content in the W20 treatment was 12.39 g/kg and 14.67 g/kg in one and two years, respectively. The maximum relative HA content in the W20 treatment was 22.99% one year after returning to the field. The PQ value (the ratio of HA/(fulvic acid (FA) + HA)) for the W20 treatment was 88.21%. The W20 treatment greatly increased the SOC and humus carbon contents. Compared with the CK treatment, all the organic materials applied for one year improved the structure of the humic acid to varying degrees, increased the degree of oxidation, reduced the degree of condensation and thermal stability of the HA in the soil, and gradually simplified the structure of the humic acid; among all the treatments, the W20 treatment had the greatest effect.

Plant-mediated synthesis, characterization, and evaluation of a copper oxide/silicon dioxide nanocomposite by an antimicrobial study

Abstract This study presents an innovative, environmentally friendly method for biosynthesizing copper oxide–silica (Cu2O/SiO2) nanocomposites (CSNCs) utilizing an aqueous leaf extract of Callistemon viminalis (C. viminalis). The goal of this work is to fabricate CSNCs using a less hazardous and sustainable synthesis approach. Copper acetate and sodium metasilicate were used as precursors, whereas the C. viminalis green leaf extract was used as the reducing and stabilizing agent. Analysis of the plant extract using Fourier transform infrared spectroscopy indicated the presence of polyphenolic compounds, primarily phenolic acids, which functioned as both reducing and stabilizing agents in the synthesis of CSNCs. A combination of energy dispersive X-ray spectroscopy and scanning electron microscopy was used to study the formation of spherical copper–silica hybrid nanostructures. Powder X-ray diffraction analysis revealed the successful integration of silica with copper(i) oxide (Cu2O) through the presence of distinct Cu2O peaks and a broad amorphous SiO2 peak at 2θ = 22.77°. The thermal stability of the nanocomposites (NCs) was assessed using thermogravimetric analysis and differential thermal analysis under a nitrogen atmosphere. The biogenic NCs also successfully inhibited pathogenic strains of Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans); however, S. aureus was found to be more susceptible to the biocidal activity of the NCs than P. aeruginosa. These findings suggest that this simple, cost-effective, and eco-friendly method for producing biologically active hybrid nanomaterials holds significant promise for future applications in both biological and materials sciences.

Synthesis, Structure, and Properties of Dion–Jacobson Double‐Layered Perovskites A′SmNb2O7 (A′ = Rb, K, Na, Li, H)

Dion‐Jacobson‐type layered perovskite compounds A′SmNb2O7 (A′ = Rb, K, Na, Li, H) were synthesized using solid‐state and ion‐exchange methods. While the parent solid‐state product RbSmNb2O7, has previously been studied, the ion‐exchanged compounds were obtained and studied for the first time. The phase and chemical purity of the compounds were confirmed by X‐ray diffraction (XRD) and energy‐dispersive X‐ray spectroscopy (EDX). The crystal structures of RbSmNb2O7 (I2cm, a=0.54356(1) nm, b=0.53935(1) nm, c=2.1891(5) nm), KSmNb2O7 (I2cm, a=0.53660(7) nm, b=0.54481(6) nm, c=2.1527(1) nm) and LiSmNb2O7 (B2cm, a=0.54546(4) nm, b=0.53567(4) nm, c=2.04582(5) nm) were refined using the Rietveld method. Polyhedral distortions in these structures have been studied in detail. The thermal behavior of the compounds has been determined using differential thermal analysis (DTA), revealing that A′ = Na, Li and H compounds are metastable hydrates, while A′ = Rb and K compounds are stable. The optical band gap, valence band edge, and conduction band edge potentials of the compounds obtained were calculated using diffuse reflection spectroscopy data. A photocatalytic experiment was performed on the degradation of methylene blue under ultraviolet light. All of the samples obtained showed some activity in the reaction of dye photooxidation.

Effect of Morphology and Concentration of CeO2 Nanoceria on the Thermal Stability of Polyvinyl Alcohol Films

Objective: To determine the thermal stability of polyvinyl alcohol films under different concentrations of CeO2 nanoceria. Method: Cerium Oxide doped polyvinyl alcohol (PVA) nano-composites were synthesized by the traditional solution casting method for various concentrations of nano CeO2 by solution combustion method. The thermal properties of prepared PVA-2.5 wt% CeO2, PVA-7.5 wt% CeO2 , PVA-12.5 wt% CeO2, and PVA-25 wt% CeO2 composite films were elucidated by using techniques such as Differential Scanning Calorimetry, Thermogravimetry analysis and Differential Thermal analysis. Findings: The glass transition temperature of the pure PVA is found to be 114°C, whereas it varies between 110°C-120°C for composite films. The melting temperature of the composite films is the same as that of pure PVA except in the case of 7.5wt% CeO2 and 25wt% CeO2 composites. The reduced melting point of these composites elicits a decrease in crystallinity. A 12.5 wt % and 25 wt% CeO2-PVA nano-composite films exhibit an increase in the final degradation temperature, a high specific heat capacity, low mass loss, and a larger residual weight, indicating their potential applicability in thermal coating and thermal sensing applications. Polyvinyl alcohol (PVA) films are being used routinely as a dielectric layer for electrical applications due to the good physiochemical and dialectic properties of the material. An incorporation of CeO2 nanoceria improves not only the thermal but also the mechanical properties of PVA and extends its application for electrical and optical operation. Here in the present study, different concentrations of CeO2 were incorporated with the PVA and analysed for the thermal properties. The study showed that 12.5 wt % and 25 wt% CeO2-PVA nano-composite enhanced PVA film thermal stability. Keywords: PVA-CeO2 Nanocomposites; Differential Scanning Calorimetry; Thermogravimetry Analysis and Differential Thermal Analysis; Physical properties and thermal properties

Effect of al content on microstructure and corrosion resistance of Zn-Al-Mg alloy

In order to solve the solidification microstructure of Zn-1.7Al-1.1Mg alloy on the surface of steel plate during hot dip plating, the solidification path and microstructure of Zn-1.7Al-1.1Mg alloy were studied by Thermo-Calc thermodynamic software, differential thermal analysis (DSC) and scanning electron microscopy (SEM). The results show that during cooling from melting to room temperature, Zn-1.7Al-1.1Mg alloy begins to precipitate Zn-rich η phase at 386.5 °C, binary eutectic structure consisting of η phase and Mg2Zn11 at 350.0 °C, and ternary eutectic structure consisting of η phase, Al-rich metastable β phase and Mg2Zn11 at 343.4 °C,at 276.7 °C, β phase transforms into stable aluminum-rich α and η phases.

Review about the history of thermal analysis in Hungary

AbstractThis review discusses the development of the Derivatograph in the 1950s and the history of thermal analysis in Hungary. This device was the first commercial simultaneous thermogravimetry and differential thermal analysis (TG/DTA) instrument of the world. It initiated the development of thermal analysis and its application possibilities in a wide range during the second half of the last century. As a result, very strong thermoanalytical schools were established in Hungary, and the first thermoanalytical journal in the world, i.e., the Journal of Thermal Analysis was started in 1969, which is still a leading journal in the field, now under the title of Journal of Thermal Analysis and Calorimetry. In addition, several periodicals and books were published in thermal analysis in Hungary. In the paper, the most important Hungarian thermal analysis-related associations, events, acknowledgements and awards are also mentioned, together with names of major Hungarian researchers in this field. Presently, beside the internationally acknowledged research groups and the JTAC, the flagship of the Hungarian thermal analysis is the Journal of Thermal Analysis and Calorimetry Conference (JTACC) series.

An analysis of the synthesis, crystal structure, optical, spectroscopic, mechanical, self-focusing, and third-order nonlinear optical properties of Kojic acid single crystals

A single, excellent crystal of Kojic acid (KA) was developed utilising the traditional approach of gradual evaporation in a solution-growing procedure. A variety of characterisation techniques were utilised to evaluate the characteristics of the crystals generated. Single crystal x-ray diffraction (SXRD) was utilised to identify the crystal structure. The crystalline arrangement of the KA crystal was confirmed using a powder x-ray diffraction (PXRD) analysis. Experiments with UV–vis spectrometers revealed that the KA crystal has a lower wavelength at which it blocks UV light but has outstanding light transmission throughout the visible spectrum. The KA single crystal has an energy band gap (Eg) of 2.5 eV. The Z-scan method was used to examine the third order susceptibility, nonlinear refraction, and nonlinear absorption coefficient of the synthesised KA crystal. The dielectric characteristics and AC conductivity were examined, with a particular emphasis on their connection to resistance at room temperature. The presence of appreciable levels of kojic acid was confirmed by energy-dispersive spectrometry. The crystal’s thermal behaviour was investigated using differential thermal analysis (DTA) and thermogravimetric (TG) methods. The nucleation parameters and controlled nucleation rate were calculated using normal theoretical research methods.

Transient Liquid Phase Bonding of ZGH451 Superalloy Fabricated by Directed Energy Deposition

ZGH451, a directionally solidified Ni‐based superalloy designed for additive manufacturing, has garnered significant attention in the realm of next‐generation turbine blades. Welding the ZGH451 superalloy is crucial for promoting its practical application. In this study, transient liquid phase (TLP) bonding is applied to weld ZGH451 superalloy produced through directed energy deposition. A Ni‐based interlayer alloy powder is developed and prepared via thermodynamic calculation, with the interlayer subsequently characterized using differential thermal analysis. TLP bonding is conducted at 1200 °C for 4 h. The influence of the preset gap on the joint microstructure and mechanical properties is examined. The microstructure of the TLP bonding joints comprises athermally solidified zones (ASZ), isothermally solidified zones, and diffusion‐affected zones. The ASZ width significantly increases with the growing preset gap. A preset gap not exceeding 100 μm enables complete isothermal solidification of the joints. Particularly, joints with a preset gap ranging from 0 to 30 μm demonstrate optimal reliability, exhibiting a tensile strength of up to 1375 MPa at room temperature, which is 12% higher than the room temperature strength of the base metal (BM), and a tensile strength of 983 MPa at 760 °C, surpassing 86% of the BM's strength at the same temperature.

Structural, morphological and optical properties of the La2W2O9/Fe2O3 composite for UV-shielding applications

Currently, research has been conducted on the individual oxides La2W2O9 and Fe2O3 but not on its composite form. Using a solid-state reaction technique, a La2W2O9/Fe2O3 composite was created. A particular calcination cycle was followed by mixing the raw precursors. Scanning electron microscopy (SEM) was used to investigate the morphological microstructure, and X-ray diffraction (XRD) was used to examine the structural characteristics. The thermal and gravimetric properties were examined via differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The optical characteristics were investigated via UV–visible spectroscopy, which investigated included the transmittance, absorbance, absorption coefficient, band gap (Eg), penetration depth (β), Urbach energy (EU), refractive index, optical conductivity, and dielectric function. These findings indicate that the optical properties improved after the addition of Fe2O3 compared with those of pure La2W2O9. The La2W2O9/Fe2O3 composite holds promise as a prospective material for use in the fields of sunscreen products, UV shielding or solar filtration.

Nanosized Eu3+-Doped NaY9Si6O26 Oxyapatite Phosphor: A Comprehensive Insight into Its Hydrothermal Synthesis and Structural, Morphological, Electronic, and Optical Properties.

Detailed analysis covered the optical and structural properties of Eu3+-doped NaY9Si6O26 oxyapatite phosphors, which were obtained via hydrothermal synthesis. X-ray diffraction patterns of NaY9Si6O26:xEu3+ (x = 0, 1, 5, 7, 10 mol% Eu3+) samples proved a single-phase hexagonal structure (P63/m (176) space group). Differential thermal analysis showed an exothermic peak at 995 °C attributed to the amorphous to crystalline transformation of NaY9Si6O26. Electron microscopy showed agglomerates composed of round-shaped nanoparticles ~53 nm in size. Room temperature photoluminescent emission spectra consisted of emission bands in the visible spectral region corresponding to 5D0 → 7FJ (J = 0, 1, 2, 3, 4) f-f transitions of Eu3+. Lifetime measurements showed that the Eu3+ concentration had no substantial effect on the rather long 5D0-level lifetime. The Eu3+ energy levels in the structure were determined using room-temperature excitation/emission spectra. Using the 7F1 manifold, the Nv-crystal field strength parameter was calculated to be 1442.65 cm-1. Structural, electronic, and optical properties were calculated to determine the band gap value, density of states, and index of refraction. The calculated direct band gap value was 4.665 eV (local density approximation) and 3.765 eV (general gradient approximation). Finally, the complete Judd-Ofelt analysis performed on all samples confirmed the experimental findings.

Effects of bamboo leaf ashes on concrete compressive strength, water absorption, and chloride penetration

Bamboo leaves are an agro-waste from the bamboo industry that carries a significant environmental impact, primarily due to its phytotoxic activity. In this paper the pozzolanic potential of bamboo leaf ashes are assessed. Bamboo leaves were calcined at five different temperatures - 500, 600, 700, 900, and 1000 °C. The obtained ashes were characterized using X-ray diffraction, X-ray fluorescence, differential thermal gravimetric analysis, Modified Chapelle's method, and Pozzolanic Activity Index. The ash calcined at 600 °C, exhibiting the highest pozzolanic activity, was used in concrete production as a partial replacement for Portland cement at levels of 5 %, 10 %, and 15 %. Concrete compressive strength, water absorption, and chloride diffusivity were assessed. The results indicate that the use of BLA significantly improves the concrete performance, increasing 28-day compressive strength by up to 18 % and reducing the non-steady state chloride penetration by up to 71.2 %. Overall, the use of bamboo leaf ashes obtained at 600 °C leads to significant improvements in mechanical and durability-related properties of concrete, indicating the viability of using this agro-waste as a supplementary cementitious material.

Experimental and theoretical studies of carbacylamidophosphate-La (III) complexes: Synthesis, crystal structure, antibacterial activity, electronic and morphology properties

The present study tries to contribute to the body of knowledge concerning the effects of O-donor ligands based on carbacylamidophosphate on the topology, geometry, and dimensions of relevant metal complexes. Accordingly, the octa-coordinated lanthanum (III) complex with formula, [La(L1)4Cl2]Cl (C1) (L1 = 4-NC5H4C(O)NHP(O)(NC6H12)2), has been synthesized and its crystal structure has been determined. In the crystal structure, C1 is C2-symmetrical, and there are separate [La(L1)4Cl2]+ cations and Cl- anions. In the complex molecule, the four L1 ligands adopt two anti- and two syn-chelating conformations. Moreover, two other carbacylamidophosphate-based lanthanide complexes La(L2)2(NO3)3 (C2) (L2 = PhC(O)NHP(O)(NH(tert‑C4H9))2)2(NO3) and La(L3)2(NO3)3(H2O)[(CH3)2CO] (C3) (L3 = (4-NO2C6H4CONHPO(NC4H8O)2) were considered and density functional theory computations, at the B3PW91 level, were performed to gain a deeper understanding of the structural and electronic properties in complexes (C1 - C3). Nano and micro-structures of (C’1 - C’3) were prepared by means of a sonochemical process to study how the reaction condition and non-covalent forces function in terms of the form as well as the size of the particles in these complexes. Thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) were performed on compounds C’1- C’3. The Hirshfeld surface analysis and NCI method were used to show the effects of non-covalent interactions on the compounds’ morphologies. The antimicrobial activity of all selected compounds has been screened against two Gram-positive (Bacillus subtilis, Staphylococcus aureus) and one Gram-negative (Escherichia coli) bacteria by well diffusion method. The results indicated that all selected compounds did not show any antibacterial activity against bacteria as compared to standard drugs.

Nanocrystalization effects on the structural, electrical and thermoelectric properties of 10KNbO3-10Fe2O3-50B2O3-30V2O5 glass for non-volatile electronic-memory devices

AbstractThe composition: 10KNbO3-10Fe2O3-50B2O3-30V2O5 (in mol%) is produced using the conventional melt quenching method and their corresponding glass–ceramic nanocomposites were studied. The structural properties of the as-quenched sample and its heat-treated samples were investigated using X-ray diffraction and differential thermal analysis. Density (ρ) was found to decrease with increasing average nanocrystallite size as the molar volume increases. Studies on thermoelectric power have been carried out. The glass–ceramic nanocomposite after 2 h of heating exhibits significant improvement of electrical conductivity. The activation energy (W), polaron radius (rp) and other parameters have been estimated in the non-adiabatic region. The current–voltage (I–V) curve of each sample was measured. A temporal analysis of current & voltage in nonlinear I–V curves show pinched hysteresis loop, which is the memristor’s fingerprint. The glass–ceramic nanocomposite after 2 h of heating exhibits a large switching window. The results of the study enable us to predict that they will be helpful for future applications of non-volatile electronic-memory devices.

Titanium ion effects on the spectroscopic and electrical characteristics of germano silicate lead alumino tellurite glass ceramics for dielectric applications

The Glass-ceramics 10GeO2-(55-x) SiO2–29PbO–5Al2O3–1TeO2 doped with varying amounts of TiO2 (0 < x < 5 mol %) were prepared through the process of melt quenching followed by heat treatment. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Differential Thermal Analysis (DTA) were used to analyze these glass ceramics besides the usual spectral studies like optical absorption, Electron Paramagnetic Resonance (EPR), Fourier Transform Infrared Spectroscopy (FTIR) and Raman. These investigations demonstrated the existence of crystalline phases that comprise complexes of Ti4+ as well as Ti3+ ions that were dispersed randomly. Additionally, it is seen that Ti3+ ions, which are more prevalent as TiO2 concentration rises, take up the tetragonally deformed octahedral positions inside the network of glass ceramics. FTIR spectra of the synthesized samples provided information regarding the existence of different structural units in the glass ceramic matrix, which included SiO4, GeO4, GeO6, PbO4, PbO6, AlO6, TeO4, TeO3, TiO4, and TiO6. At 30 °C, the 3 mol % Ti-doped sample has a minimum conductivity of 1.623 × 10−9 S cm−1. Therefore, the dielectric and spectroscopic investigations suggest that glass ceramics containing 3 mol% of TiO2 are rigid and appropriate for dielectric applications.

Removal of acetyl-rich impurities from chitosan using liquefied dimethyl ether

Chitosan, recognized for its excellent biodegradability, biocompatibility, and antibacterial properties, has several potential applications, particularly in the biomedical field. However, its widespread use is hindered by inherent limitations such as low mechanical strength and safety concerns arising from a low degree of deacetylation and the presence of impurities. This study aimed to introduce an innovative purification method for chitosan via liquefied dimethyl ether (DME) extraction. The proposed technique effectively addresses the challenges associated with chitosan by facilitating deacetylation and impurity removal. Liquefied DME is emerging as the extraction solvent of choice owing to its advantages, such as low boiling point, safety, and environmental sustainability. The degree of deacetylation of chitosan was extensively evaluated using thermogravimetric–differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, intrinsic viscosity measurements, solid-state nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy, and elemental analysis. The solubility of chitosan in liquefied DME was investigated using Hansen solubility parameters. This study contributes to the improvement of the safety profile of chitosan, thereby expanding its potential applications in various fields. The use of liquefied DME as an extraction solvent proved to be efficient in addressing the existing challenges and is consistent with the principles of safety and environmental sustainability.

Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses.

Silicate glasses containing silicon, sodium, phosphorous, and calcium have the ability to promote bone regeneration and biodegrade as new tissue is generated. Recently, it has been suggested that adding SrO can benefit tissue growth and silicate glass dissolution. Motivated by these recent developments, the effect of SrO/CaO-CaO/SrO substitution on the local structure and dynamics of Si-Na-P-Ca-O oxide glasses has been studied in this work. Differential thermal analysis has been performed to determine the thermal stability of the glasses after the addition of strontium. The local structure has been studied by neutron diffraction augmented by Reverse Monte Carlo simulation, and the local dynamics by neutron Compton scattering and Raman spectroscopy. Differential thermal analysis has shown that SrO-containing glasses have lower glass transition, melting, and crystallisation temperatures. Moreover, the addition of the Sr2+ ions decreased the thermal stability of the glass structure. The total neutron diffraction augmented by the RMC simulation revealed that Sr played a similar role as Ca in the glass structure when substituted on a molar basis. The bond length and the coordination number distributions of the network modifiers and network formers did not change when SrO (x = 0.125, 0.25) was substituted for CaO (25-x). However, the network connectivity increased in glass with 12.5 mol% CaO due to the increased length of the Si-O-Si interconnected chain. The analysis of Raman spectra revealed that substituting CaO with SrO in the glass structure dramatically enhances the intensity of the high-frequency band of 1110-2000 cm-1. For all glasses under investigation, the changes in the relative intensities of Raman bands and the distributions of the bond lengths and coordination numbers upon the SrO substitution were correlated with the values of the widths of nuclear momentum distributions of Si, Na, P, Ca, O, and Sr. The widths of nuclear momentum distributions were observed to soften compared to the values observed and simulated in their parent metal-oxide crystals. The widths of nuclear momentum distributions, obtained from fitting the experimental data to neutron Compton spectra, were related to the amount of disorder of effective force constants acting on individual atomic species in the glasses.

Investigation of halloysite thermal decomposition through differential thermal analysis (DTA): Mechanism and kinetics assessment

The study focused on analysing the kinetics of halloysite decomposition using the differential thermal analysis (DTA) technique. Tests were carried out across a temperature span from ambient temperature to 1673 K, employing heating rates spanning from 5 to 20 °C.min−1. X-ray diffraction and Fourier transform infrared spectroscopy (FT-IR) were utilized to identify the phases formed at different temperatures. Activation energies for halloysite decomposition were determined through isothermal and non-isothermal treatments, yielding values of approximately 151.68 kJ mol−1 and 173.14 kJ mol−1, respectively. The Ligero method's Avrami constant parameter (n) and the Matusita method's numerical factor parameter (m), linked to crystal growth dimensions, were both around 1.5. These findings indicate that the degradation of halloysite is primarily governed by bulk nucleation, succeeded by the 3-dimensional growth of meta-halloysite characterized by polyhedron-like structure, regulated by diffusion from a consistent number of nuclei. The frequency factor for halloysite dehydroxylation was established at 8.48 × 10⁸ s⁻1.

Nd3+-Doped Scheelite-Type Multifunctional Materials-Their Thermal Stability and Magnetic Properties.

New Nd3+-doped cadmium molybdato-tungstates with the chemical formula of Cd1-3x▯xNd2x(MoO4)1-3x(WO4)3x (where x = 0.0283, 0.0455, 0.0839, 0.1430, 0.1875, 0.2000, 0.2500, and ▯ denotes a vacant site in the crystal lattice) were successfully synthesized by the high-temperature solid state reaction method, using CdMoO4 and Nd2(WO4)3 as the initial reactants. The structure and change in their lattice parameters as a function of Nd3+ ion concentration were investigated by the XRD (X-ray diffraction) method. The surface morphology and grain size of the doped materials were characterized by SEM (scanning electron microscopy). Their thermal properties and initial reactants were analyzed by DTA-TG (differential thermal analysis coupled with thermogravimetry) techniques. The optical properties of the Nd3+-doped cadmium molybdato-tungstates, such as optical band gap, were determined by UV-vis-NIR (ultraviolet-visible-near infrared) spectroscopy. The EPR (electron paramagnetic resonance) technique provided information on the type of magnetic interactions between Nd3+ ions.

Thermal Compatibility of New ACEI Derivatives with Popular Excipients Used to Produce Solid Pharmaceutical Formulations.

Background/Objectives: Increasing drugs' stability and adequately protecting them against degradation will ensure a decrease in their price and broader availability of pharmaceutical substances. This is of great importance, especially for drugs used to treat the most common diseases in the population, such as hypertension. The study examined two newly synthesized substances from the angiotensin I-converting enzyme inhibitor (ACEI) group as potential drugs. ACEIs are among the leading drugs used in the treatment of hypertension in the world. The chemical modifications of the tested substances applied concerned the places most susceptible to degradation. The presented work analyzed the compatibility of new derivatives with selected excipients used in pharmacy. Methods: Thermogravimetric (TGA) and differential thermal analyses (c-DTA) were used as the main methods. In addition, non-thermal methods such as colorimetry analysis, Fourier-transform infrared (FTIR) and UV spectroscopy were used. Results: Based on the conducted studies, it can be concluded that the incompatibility of IND-1 with glucose anhydrous and lactose monohydrate occurs only when the mixture is stored at higher temperatures. For the remaining IND-1 and IND-2 mixtures with excipients, compatibility was demonstrated. Conclusions: The obtained results confirmed the usefulness of the applied thermal analyses (TGA and c-DTA) for assessing the compatibility of the tested potential drugs with excipients. However, in the case of incompatibility reactions of substances occurring under the influence of elevated temperatures, such as the Maillard reaction, it is necessary to use non-thermal methods to obtain the right result.