Marina Valeryevna Kuimova

Calcium Oxalates: Thermodynamic and Kinetic Conditions of Their Formation in the Presence of Organic Components

The paper researches a range of problems related to the peculiarities of calcium oxalate crystallization in the presence of amino acids on the bases of thermodynamic calculations and experimental data. The regularities of phase formation in the system Ca2+–C2O4 2−–H2O–amino acid in a widely variable interval of component concentrations and pH are theoretically researched. The influence of pH on the thermodynamic stability of crystalline compounds is considered. The kinetic parameters of crystallization are determined: the induction period, the rate constant, the order of crystals’ growth, and the influence of amino acids on the kinetics of crystallization of calcium oxalate is established.

Biomimetic Synthesis of Strontium-Containing Apatite and Its Peculiar Properties

This paper examines the influence of strontium chloride on the process of crystallization of strontium-substituted carbonated hydroxyapatite from prototype human synovial fluid. Products of synthesis were studied by Fourier transform infrared spectroscopy, X-ray diffraction, and differential thermal analysis. The amount of strontium in the sample using atomic emission analysis was determined. For the synthesized phases, Ca/P-ratio, the parameters of crystallinity, the crystallite size using the formula of Selyakov-Scherrer, and crystal lattice parameters were calculated. It was established that increasing the concentration of strontium ions in the analytical model increases the proportion of brushite in the solid phase. It was found that with increasing formation of a precipitate beneath the mother liquor, the kinetically stable-phase of brushite transforms to the thermodynamically more stable phase (Sr-containing carbonated hydroxyapatite).

Kinetic Characteristics of Crystallization in Prototypes of Biological Fluids

This chapter presents the results of research on the kinetics of nucleation and crystal growth in solutions simulating the composition of human saliva and plasma. The kinetic characteristics of the processes (order, constant, activation energy, specific surface energy, the size of the critical nucleus) were obtained. The influence of some inorganic (magnesium ions) and organic (protein, alanine and glucose) additives on the kinetics of crystallization is shown.

Use of Simulation Methods of Wave Processes for Non-Destructive Testing of Concrete Products of Different Geometrical Size

Theoretical and experimental research of electrical responses under pulsed mechanical excitation of different size concrete products was carried out. Comparison of calculated and experimental data shows very close agreement. The obtained results will help to develop new opportunities to improve the method of non-destructive testing of concrete by creating a bank of calculated electrical responses from products of different geometrical arrangement and elastic response and using them as standard samples for defectiveness evaluation of products according to previously established criteria.

Research of Electrical Response Communication Parameters on the Pulse Mechanical Impact with the Stress–Strain State of Concrete Under Uniaxial Compression

The article presents the results of research of the electrical response on elastic impact excitation of heavy concrete samples under uniaxial compression. In this paper we recorded and analyzed electrical responses during uniaxial compression of concrete samples with a constant velocity. Studies have shown that in the process of uniaxial compression of concrete samples, the transformation of amplitude–frequency characteristics of the electrical response is observed. The stage of elastic deformation of concrete samples is characterized by a centershift of gravity of the spectrum of the electrical response towards lower frequencies. Dramatic centershift of gravity of the spectrum of the electrical response to the high frequency region characterizes the beginning of fracturing.