Temperature Dependences of the Magnetic Susceptibility of Water-Based Magnetic Fluids

This paper presents the results of a study of the temperature dependences of the magnetic susceptibility of water-based magnetic fluids (magnetic colloids) with magnetite particles stabilized by their electrostatic interaction. The average size of dispersed particles was 8 nm, and the volume concentration of particles in the selected samples under study was 1.4% and 1.6%. The investigations were carried out over a wide temperature range. The temperature dependence of the susceptibility, for the first time, was obtained in the region of the colloidal phase transition under supercooling of the dispersion medium (water). Significant differences were found between the temperature dependences of the magnetic susceptibility of such magnetic fluids, where as similar dependences have been found for the susceptibility of magnetic hydrocarbon-based fluids. The observed behavior of such dependences near the water phase transition temperature is determined by the changes in the water phase state, heat release and structuring of the colloid as a result of water crystallization. Moreover, it is suggested that a certain impact on the dependence behavior in the region of the colloidal solidification temperature can also come from the process of blocking the Brownian degrees of freedom of a small fraction of large dispersed particles. It is concluded that the observed maxima in the investigated susceptibility temperature dependences in the lower temperature region are due to magnetic transformations in the colloidal zones formed at the solidification front of the disperse medium with a dense packing of single-domain colloidal particles.

Особенности стандартизации химических реагентов для подготовки питьевой воды (на примере коагулянта полиоксихлорида алюминия)

Распространенным технологическим приемом удаления из воды грубодисперсных примесей, находящихся во взвешенном состоянии, а также коллоидных органических загрязнений, присутствующих в растворенном виде, является процесс коагуляции. Эффективными коагулянтами для систем с водной дисперсионной средой являются соли поливалентных металлов. Цель работы заключалась в создании нового государственного стандарта, предназначенного для обеспечения единообразной оценки качества коагулянтов. Рассмотрена область применения коагулянтов в процессе водоподготовки и проведен их сравнительный анализ. Показана необходимость унификации в области процессов контроля качества коагулянтов. Сформулированы общие требования к контролю качества полиоксихлорида алюминия. Представлен разработанный и утвержденный новый национальный стандарт ГОСТ Р 58580-2019 Полиоксихлорид алюминия. Технические условия , который учитывает требования санитарного законодательства, технического регулирования, безопасности процессов производства и транспортировки полиоксихлорида алюминия.Coagulation process has been a widespread process technology for removing coarse suspended impurities from water, as well as colloidal organic contaminants present in dissolved form. Polyvalent metal salts are effective coagulants for the systems with aqueous disperse medium. The purpose of the work was developing a new state standard to provide for a uniform assessment of the quality of coagulants. The scope of coagulants in the process of water treatment is considered and their comparative analysis is carried out. The general requirements to the control of polyaluminium chloride quality are formulated. The developed and approved new national standard GOST R 58580-2019 Polyaluminium chloride. Technical conditions is presented that takes into account the requirements of sanitary legislation, technical regulation, safety of the processes of production and transportation of polyaluminium chloride.

Results of Spectral Analysis of the Effective Flushing Liquid

The article is devoted to the results of spectral analysis of effective flushing liquid with the use of lightweight polymeric reagent (LPR). On the basis of spectral research it is shown that the mechanism of ion exchange of particles of flushing liquid (replacement reaction) at replacement of mineral in the crystal lattice by cat ions of disperse medium is a permanent replacement of organic and inorganic cat ions of flushing liquid with rock particles and whole groups of dispersive medium. The results of the processes of addition of fluids and rock elements to the flushing liquid particles, as well as simultaneously occurring ion-exchange and none change processes determining the mechanisms of inhibition (reduction of hydrophilicity), stabilization and colloidal protection in flushing liquids are obtained.

А METHOD OF EVALUATING THE ABSORPTION SPECTRUM OF WHEAT LEAF BY THE SPECTRUM OF DIFFUSE REFLECTION

Spectral analysis methods are widely used to assess the condition of plants during normal growth and the development of infections. In combination with mathematical methods of pattern recognition from reflection spectra, different indices are constructed, which vary for plants in different studied physiological (and pathophysiological) states. This approach involves setting up indices for specific shared states. Information about the content of pigments is more universal, and allows to talk about the state of the plant on the basis of physiological concepts, regardless of the task being solved. Methods of reflective spectroscopy have recently been developed to obtain information about the content of pigments. The absorption spectrum is estimated from the diffuse reflection spectrum based on the light propagation model in a disperse medium. One of the models of this type is the model Kubelka-Munch. In the case of the large optical thickness of the sample, when the flow passing through the sample at the output is almost zero, one can use a simplified formula, which does not include the thickness of the sample. In other cases, it is necessary to measure this thickness, which is problematic for such biological objects as a plant leaf, because of the complex relief of the leaf surface. The article presents the measurement method and results of studying the applicability of the formula Kubelka-Munch for obtaining absorption spectra from reflection spectra of a wheat leaf without measuring its thickness. The formula is derived for calculation of Kubelka-Munch function (ratio of the absorption coefficient to the diffusion coefficient) by two measurements of diffusion scattering coefficients from the sample, which are performed with absorbing and reflecting substrates. The method allows to calculate the ratio of the absorption coefficient to the diffusion coefficient without measuring the thickness of the sample under study. This index can be used as an assessment criteria of the absorption spectrum with some proportionality factor. It is possible to recommend the method described as the most valid and accurate one for the determination of the absorption coefficient to the diffusion coefficient ratio of a leaf in the laboratory conditions.

To modeling the dynamics of system of fluid and disperse medium

This paper reviewed literature related to the simulation of processes in systems of fluids and disperse medium. The main aspects of modeling two-phase flows using continuum approach are presented. This paper also highlights major difficulties of developing such models, the basic parameters that determine the state of dispersed phase and methods of calculating the kinetics of coagulation. An analysis was conducted of the forces acting on the particle in the flow.