A5045235666- Analytical Chemistry and Chromatography
- Advanced Cellulose Research Studies
- Material Dynamics and Properties
- Surfactants and Colloidal Systems
- Liquid Crystal Research Advancements
- Carbon Nanotubes in Composites
- Aerogels and thermal insulation
- thermodynamics and calorimetric analyses
- Advanced Fiber Optic Sensors
- Polymer crystallization and properties
- Thermodynamic properties of mixtures
- Electrowetting and Microfluidic Technologies
- Chemical and Physical Studies
- Graphene research and applications
- Hydrogels: synthesis, properties, applications
- Mesoporous Materials and Catalysis
- Mechanical and Optical Resonators
- Analytical Chemistry and Sensors
- Nonlinear Dynamics and Pattern Formation
- Advanced Scientific Research Methods
- High voltage insulation and dielectric phenomena
- Graph theory and applications
- Nonlinear Waves and Solitons
- Lipid Membrane Structure and Behavior
- Spectroscopy Techniques in Biomedical and Chemical Research
National University of Food Technologies
2016-2025
We examined the amorphocrystalline structures of polyethylene glycol 400 (PEG-400) using thermogravimetric, calorimetric, X-ray phase analysis, dielectric and IR spectroscopies. The physical properties such a system are affected by presence water, due to formation hydration shell. When amorphic-crystalline PEG-400 is heated, it undergoes first low-temperature then high-temperature relaxation. demonstrate that relaxation conformational motion PEG molecule’s HO–CH2–CH2– end groups. In contrast...
This article is devoted to the investigation of microcrystalline cellulose (MCC).X-ray diffraction analysis allowed estimating radius particles (whiskers), while dielectric spectroscopy method gave an insight into mean-square change dipole moment per unit volume and concentration relaxers as a result.The moisture content MCC samples was estimated using thermogravimetric analysis.According experimentally obtained data, we propose model describe relaxation in being caused by reorientation...
The paper discusses the influence of silica gel pores' size on structure and dielectric properties nanocrystals undecylenic acid with view determining molecular mechanisms possible pharmacological activity similar substances. To achieve these goals, powder XRD method was utilized. formed in pores show absence order along long axes molecules. relaxation bulk its studied using spectroscopy. decrease led to a temperatures process. We relate this shift formation additional stresses caused by...
The solid-state phase transition in the silica gel–1-octadecene system has been studied at various temperatures with help of differential scanning calorimetry and FTIR spectroscopy. Silica gels KSK-2.5, KSS-4, Gel 60 different surface parameters are used. temperature is shown to linearly depend on ratio between pore area volume. energy characteristics 1-octadecene nanocrystals layer calculated framework a thermodynamical model crystal melting pores.
Influence of confined space silicon nanopores on the structure, thermal motion and phase transitions 1-octadecene crystals was studied by powder XRD, FTIR thermophysical methods. Decrease melting temperature as well solid temperatures due to confinement effect detected. Additionally transition in near-surface layer found. The molecular this system interpreted accordance with topological solitons model.Shortened version title: Structure 1-octadecene, pores porous silicon.
We have compared the structure, phase transitions and thermal motion mechanisms of undecylenic acid in bulk inside a porous matrix using powder X-ray diffraction, calorimetry IR-spectroscopy methods. The used was silicon with cylindrical pores (D = 20 nm). interaction between walls nanocrystals results crystalline which is significantly different from structure acid. A transition wall-adjacent layer shown to take place. solid-state temperatures, as well melting point, were be lower for...
The study of relaxation processes in porous inhomogeneous systems via dielectric and mechanical spectroscopy methods is associated with methodological difficulties. To understand how IR can be used to elucidate the temperature-dependent changes that take place undecylenic acid - silica gel systems, such as phase transition processes, we compare spectroscopic data previously obtained for bulk embedded matrices different pore sizes. We demonstrate topological soliton model both acid,...
The paper discusses mechanisms of molecular motion in lamellar chain crystals the stearic acid. Thermal calorimetry, dielectric and IR-spectroscopy methods indicate a phase transition from orthorhombic crystal into rotator vicinity Тrot = 50 °С. This allows for excitation topological solitons, which reorient aliphatic by 180° translate it one link. These solitons form at terminal methyl groups and, upon propagating along chain, are reflected dimeric ring until their energy is high enough to...
The results of the study Na <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> and Cl xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> ions effect on properties hydroxypropyl cellulose (HPC) water solution are presented. influence these density, viscosity, HPC nanoparticles sizes temperature structural transitions in smart systems is revealed. It shown that luminescence characteristics sensitive to changes structure allowing determination...
We discuss and analyze the dependence spectra of transmission coefficient T on quasiparticle energy E one variety graphene-based Fibonacci superlattices (SL). The SL is built from armchair graphene nanoribbons (GNR), quasi-periodicity produced by metal-like (MGNR) semiconductor (SCGNR) ribbons, placed along lattice growth axis in accordance with sequence, which are used as individual elements. It shown that difference values quantized transverse quasi-momentum electrons MGNR SCGNR enough to...
We describe a mechanism of pre-transition process near the sol-gel transition temperature in sol-phase water solutions rigid-chain polymers. During this boundary layer is disordered, and voids are formed it. The variation density hydroxypropyl methylcellulose with measured experimentally for temperatures between 25 80 °C. experiment supports proposed mechanism.