Inhibition of naproxen crystallization by polymers: The role of topology and chain length of polyvinylpyrrolidone macromolecules.

This paper presents an innovative approach that utilizes self-synthesized homopolymers of polyvinylpyrrolidone (PVP) with different architectures as effective matrices for inhibiting the crystallization of naproxen (NAP). We have thoroughly investigated amorphous solid dispersions containing NAP and (i) self-synthesized linear PVP, (ii) self-synthesized three-armed star-shaped PVP, and (iii) self-synthesized linear PVP with a mass (M) corresponding to the length of one arm of the star polymer, as well as (iv) commercial linear PVP K30 as a reference. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and infrared spectroscopy (FTIR) studies, as well as molecular dynamics simulations were conducted to gain comprehensive insights into the thermal and structural properties, as well as intermolecular interactions in the NAP-PVP systems.

Variation of Activation Volume as an Indicator of the Difference in Clusterization Phenomenon Induced by H-Bonding and F-Π Stacking Interactions in Enantiomers and a Racemate of Flurbiprofen.

In this paper, X-ray diffraction (XRD), differential scanning calorimetry (DSC), broadband dielectric (BDS), and Fourier transform infrared (FTIR) spectroscopy supported by molecular dynamics (MD) simulations and quantum chemical computations were applied to investigate the structural and thermal properties, molecular dynamics, and H-bonding pattern of -, -, and -flurbiprofen (FLP). Experimental data indicated various spatial molecular arrangements in crystalline forms of examined systems, which seemed to disappear in the liquid state. Surprisingly, deeper analysis of high-pressure dielectric data revealed unexpected variation in the activation volume of pure enantiomers and a racemate.

The existence of a strongly bonded layer in associating liquids within silica pores - a spectral and molecular dynamics study.

The properties of confined materials are assumed to be governed by the phenomena occurring at the interface, especially the formation of an irreversible adsorption layer (IAL), which has been widely discussed and detected in the case of thin polymer films and silica nanoparticles. In this paper, we present a novel experimental approach allowing us to reveal the formation of an IAL in two phenyl alcohols infiltrated into various mesoporous silica templates. The proposed methodology (based on evaporation) allowed us to detect the alterations in the OH and aromatic CH stretching vibration bands in infrared spectra, which were considered as evidence of the existence of IAL in constrained systems.

Pressure-Induced Aggregation of Associating Liquids as a Driving Force Enhancing Hydrogen Bond Cooperativity.

The behavior of hydrogen bonds under extreme pressure is still not well understood. Until now, the shift of the stretching vibration band of the X-H group (X = the donor atom) in infrared spectra has been attributed to the variation in the length of the covalent X-H bond. Herein, we combined infrared spectroscopy and X-ray diffraction experimental studies of two H-bonded liquid hexane derivatives, i.

Comparison of Physicochemical, Mechanical, and (Micro-)Biological Properties of Sintered Scaffolds Based on Natural- and Synthetic Hydroxyapatite Supplemented with Selected Dopants.

The specific combinations of materials and dopants presented in this work have not been previously described. The main goal of the presented work was to prepare and compare the different properties of newly developed composite materials manufactured by sintering. The synthetic- (SHAP) or natural- (NHAP) hydroxyapatite serves as a matrix and was doped with: (i) organic: multiwalled carbon nanotubes (MWCNT), fullerenes C60, (ii) inorganic: Cu nanowires.

Influence of Magnetite Nanoparticles Shape and Spontaneous Surface Oxidation on the Electron Transport Mechanism.

The spontaneous oxidation of a magnetite surface and shape design are major aspects of synthesizing various nanostructures with unique magnetic and electrical properties, catalytic activity, and biocompatibility. In this article, the roles of different organic modifiers on the shape and formation of an oxidized layer composed of maghemite were discussed and described in the context of magnetic and electrical properties. It was confirmed that FeO nanoparticles synthesized in the presence of triphenylphosphine could be characterized by cuboidal shape, a relatively low average particle size (9.

Effect of Co Substitution and Thermo-Magnetic Treatment on the Structure and Induced Magnetic Anisotropy of FeCoNbBP Nanocrystalline Alloys.

In the present work, we investigated in detail the thermal/crystallization behavior and magnetic properties of materials with FeCoNbBP (x = 0, 5, 10, 15 and 20 at.%) composition. The amorphous ribbons were manufactured on a semi-industrial scale by the melt-spinning technique.

Influence of Cu Content on Structure, Thermal Stability and Magnetic Properties in FeNiNbCuSiB Alloys.

The effect of substitution of Fe by Cu on the crystal structure and magnetic properties of FeNiNbCuSiB alloys ( = 0.6, 1.1, 1.

The Structure and Magnetic Properties of Rapidly Quenched FeNiNbSiB Alloy.

The complex structural and magnetic studies of the annealed rapidly quenched Cu-free FeNiNbSiB alloy (metallic ribbons form) are reported here. Based on the calorimetric results, the conventional heat treatment process (with heating rate 10 °C/min and subsequent isothermal annealing for 20 min) for wound toroidal cores has been optimized to obtain the least lossy magnetic properties (for the minimum value of coercivity and magnetic core losses at 50 Hz). For optimal conditions, the complex permeability in the 10-10 Hz frequency range together with core power losses obtained from magnetic induction dependence up to the frequency of 400 kHz was successfully measured.

Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates.

The dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [BiO] layers and their growth, which increased the intensity of the (101) diffraction peak.

Fe-Co-B Soft Magnetic Ribbons: Crystallization Process, Microstructure and Coercivity.

In this work, a detailed microstructural investigation of as-melt-spun and heat-treated FeCoB ribbons was performed. The as-melt-spun ribbon was predominantly amorphous at room temperature. Subsequent heating demonstrated an amorphous to crystalline α-(Fe,Co) phase transition at 403 °C.

Influence of Cu Content on Structure and Magnetic Properties in FeCuB Alloys.

Influence of Cu content on thermodynamic parameters (configurational entropy, Gibbs free energy of mixing, Gibbs free energy of amorphous phase formation), crystallization kinetics, structure and magnetic properties of FeCuB (x = 0, 0.4, 0.55, 0.

Effect of Co Substitution on Crystallization and Magnetic Behavior of FeCoCuB Metallic Glass.

The effects of Co for Fe substitution on magnetic properties, thermal stability and crystal structure of FeCoCuB (x = 0, 2.5, 5, 7.5, 10) melt spun amorphous alloys were investigated.

Dielectric and electromagnetic interference shielding properties of high entropy (Zn,Fe,Ni,Mg,Cd)FeO ferrite.

The new (Zn,Mg,Ni,Fe,Cd)FeO high entropy ferrite with average crystallite size 11.8 nm was synthesized in two stages by annealing of co-precipitated amorphous precursor. The dielectric spectroscopy confirms, that the electrical conductivity and polarization processes are associated with the mobility of electrons in the structure of ferrite.

Electrical Conduction Mechanism and Dielectric Properties of Spherical Shaped Fe₃O₄ Nanoparticles Synthesized by Co-Precipitation Method.

On the basis of dielectric measurements performed in a wide temperature range (173⁻373 K), a comprehensive analysis of the dielectric and electrical properties of magnetite nanoparticles electrical conduction mechanism of compressed spherical shaped Fe₃O₄ nanoparticles was proposed. The electrical conductivity of Fe₃O₄ nanoparticles was related to two different mechanisms (correlated barrier hopping and non-overlapping small polaron tunneling mechanisms); the transition between them was smooth. Additionally, role of grains and grain boundaries with charge carrier mobility and with observed hopping mechanism was described in detail.

Magnetocaloric Properties of MnFePAsGe (0 ≤ x ≤ 0.1) Compounds.

Intermetallic compounds with the overall formula MnFePAsGe ( varies from 0 to 0.1) were investigated in order to study their magnetocaloric effect by monitoring the adiabatic temperature change, magnetic entropy change and their relation to structural parameters. It was found that the maximum of magnetocaloric effect was achieved for = 0.

Molecular origin of enhanced proton conductivity in anhydrous ionic systems.

Ionic systems with enhanced proton conductivity are widely viewed as promising electrolytes in fuel cells and batteries. Nevertheless, a major challenge toward their commercial applications is determination of the factors controlling the fast proton hopping in anhydrous conditions. To address this issue, we have studied novel proton-conducting materials formed via a chemical reaction of lidocaine base with a series of acids characterized by a various number of proton-active sites.

Rheological study of mutarotation of fructose in anhydrous state.

Rheological measurement was employed to study the mutarotation of D-fructose in anhydrous state. By monitoring the evolution of shear viscosity with time, rate constants for mutarotation were estimated, and two different stages of this reaction were identified. One of the mutarotation stages is rapid and has a low activation energy, whereas the other is much slower and has a much higher activation energy.

Fragility versus activation volume: insight into molecular dynamics of glass-forming hydrogen-bonded liquids.

In this Brief Report we show that key parameters, the fragility m(p) and activation volume ΔV, which characterize the sensitivity of molecular dynamics near the glass transition to temperature and pressure changes, respectively, reflect molecular properties in a nonequivalent way. Our comparative study of fragilities and activation volumes of isomeric pentiols provides evidence that the parameter m(p) can distinguish different H-bonded structures, even if molecular volumes are similar; however, the value of ΔV recognizes mainly the size of a relaxing molecular unit and correlates to the length scale of molecular cooperativity. Thus there is a striking difference in information given by m(p) and ΔV.

Dynamics of α-tetralone at elevated pressure and in mixture with oligostyrene.

By using the dielectric relaxation method, we studied molecular dynamics of α-tetralone. Our purpose was to reveal the molecular origin of secondary processes observed for this very simple-structured molecule. To this end, we carried out dielectric measurements at both ambient and elevated pressure of neat α-tetralone and in mixture with oligostyrene.

Dielectric properties of two diastereoisomers of the arabinose and their equimolar mixture.

Dielectric relaxation measurements were performed on two enantiomers, D- and L-arabinose and their equimolar mixture, and compared to dielectric data obtained for D-ribose. D-Arabinose differs from d-ribose by having the opposite configuration at C2. This study reveals that both D- and L- of arabinose exhibit alpha-relaxation peaks with the same shape for the same alpha-relaxation time tau(alpha), and the same steepness index for the T(g)-scale T-dependence of tau(alpha).