Формирование энергетических свойств поверхности глинистых частиц, модифицированных высоким давлением

The article considers the issues of changing the energy activity of the surface of clay particles modified by pressure up to 800 MPa. The energy properties of the surface were evaluated by measuring the adhesion force between the surface of clay samples and the silicon cantilever of an atomic force microscope. It has been proved that when clay soils are modified by stress pressure, the adhesion force changes in different directions in clays with different mineral composition. So, in kaolin clay, with an increase in pressure from 25 to 800 MPa, the adhesion force increases, respectively, from 0.25 to 0.78 nN. In clays of montmorillonite composition, an increase in pressure to 150 MPa leads to an increase in the adhesive interaction, and a further increase in the load to 800 MPa leads to its decrease.Рассматриваются вопросы изменения энергетической активности поверхности глинистых частиц, модифицированных давлением величиной до 800 МПа. Энергетические свойства поверхности оценивалась путем измерения силы адгезии между поверхностью глинистых образцов и кремниевым кантилевером атомно-силового микроскопа. Доказано, что при модифицировании глинистых грунтов стрессовым давлением, сила адгезии изменяется разнонаправлено в глинах с различным минеральным составом. Так, в каолиновой глине при увеличении давления от 25 до 800 МПа, сила адгезии возрастает соответственно от 0,25 до 0,78 нН. В глинах монтмориллонитового состава рост давления до 150 МПа приводит к усилению адгезионного взаимодействия, а дальнейшее увеличение нагрузки до 800 МПа − к его снижени

Преобразование адсорбционных свойств бентонитовых глин путем комплексного техногенного воздействия

The results of study of the change in the sorption index by chemical, thermal and mechanical treatment of bentonite clay have been obtained. They showed that during the complex processing of samples with mechanical pressure, temperature and cationic solutions, there is a general tendency to an increase in the sorption index. It was found that the greatest effect on the activation of sorption properties is exerted by vertical pressure, heat treatment of samples at 200 оС and saturation with a cationic solution of ferric chloride, which allows us to consider this processing of samples as the most effective for the samples of this study.Получены результаты исследования бентонитовой глины на изменение показателя сорбции химической, термической и механической обработкой. Результаты показали, что при комплексной обработке образцов с механическим давлением температурой и катионными растворами наблюдается общая тенденция увеличения показателя сорбции. Установлено, что наибольшее воздействие на активацию сорбционных свойств оказывает вертикальное давление, термообработка образцов в 200℃ и насыщение катионным раствором хлорида железа, что позволяет считать данную обработку образцов наиболее эффективной для образцов данного исследования

Случай первичной солитарной плазмоцитомы трахеи

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Regularities of zero charge formation on the surface of clay particles exposed to pressure

Relevance. Caused by the need to study the effect of high pressure on the change in pH value of the point of zero charge of clay minerals. The point of zero charge is one of the most important characteristics of a diluent. The magnitude of the charge is largely controlled by the pH values of a pore solution. As it is known, clays of different genesis have excellent physical and chemical properties, which directly affects the value of the zero charge point. Aim. To identify the patterns of formation of the zero charge point of clay particles exposed to pressure. Objects. Kaolin clay of the Nizhne-Uvelsky deposit of the Chelyabinsk region and bentonite clay of the Zyryanovsky deposit of the Kurgan region. Methods. potentiometric titration, determination of the point of zero charge was carried out using the construction of potentiometric titration curves. Microsoft Excel, SigmaPlot, Statistica software was used. Results. When processing clays by pressure, there is a decrease in the content of aluminum ions (Al3+) in the packages of kaolinite and montmorillonite, the transition of Al3+ ions into the diffuse layer of the clay particle, where aluminum ions bind hydroxyl ions, while the released hydrogen ions increase the acidity of the suspension. Activation by pressure of kaolin and bentonite clays has a multidirectional effect on the change in the ion-exchange capacity of clays and, as a result, on the pH of the point of zero charge on the surface of clay particles. The authors developed statistical models that allow predicting the pH of the zero charge point from clay activation pressure data. Knowledge of the characteristics of the charge on the surface of clay particles makes it possible to explain the mechanism of sorption and other processes

Mechanism of interaction among nanocrystalline carbonate-substituted hydroxyapatite and polar amino-acids for the biomimetic composite technology: Spectroscopic and structural study

This study investigated changes in the interaction of B-type non-stoichiometric nanocrystalline carbonate-substituted hydroxyapatite (nano-CHAP) with polar amino acids (AA) with respect to CHAP-AA linking. Molecular vibrational spectroscopy revealed for the first time that the surface interaction of polar amino acids with defective nano-CHAP is determined not only by the charge state of AA but can be mediated by a foreign ion conjugated with the lateral bonds of amino acids. Understanding this mechanism of CHAP-AA interaction is required for the development of the new generation of dental biomimetic materials based on HAP as well as for their qualitative integration with the amino acid matrix of the dental tissues. © 2020Russian Foundation for Basic Research, RFBR: MK-419.2019.2, 18-29-11008The study was performed under support of Russian Foundation for Basic Research (RFBR) grant №18-29-11008 mk and grant of the President of Russian Federation №MK-419.2019.2

XANES Investigation of the Influence of a Coordinating Atomic Environment in Biomimetic Composite Materials

In our work, the influence of the coordination environment of the Ca atom states in biomimetic mineralizing composite dental materials integrated with dental tissue was investigated. Biomimetic composites as well as natural dental tissue samples were investigated using synchrotron X-ray absorption near edge structure (XANES) spectroscopy. Energy structure studies revealed a number of important features related to the different type of calcium atom environment. the surface of nanocrystalline calcium carbonate-substituted hydroxyapatite (nano-cHAp) crystals in natural enamel and dentin involved in the formation of bonds with the organic matrix is more characterized by the coordination environment of the calcium atom corresponding to its location in the CaI position, i.e. bound through common oxygen atoms with PO4 tetrahedrons. At the same time, on the surface of nano-cHAp crystals in bioinspired dental materials, the calcium atom is more characteristically located in the CaII position, bound to the hydroxyl OH group. The detected features in the coordination atomic environment in nano-cHAp play a fundamental role for engineering a biomimetic dental composite of the natural organomineral interaction in the mineralized tissue. © 2022 The Authors.This work was funded by the grant of Russian Science Foundation, grant number 21-75-10005. The access to scientific equipment and methodology was provided under support of the Ministry of Science and Higher Education of Russia, Agreement N 075-15-2021-1351

Sorption ability of clays exposed to compression

The paper discusses the effect of high pressures on adsorption of inorganic ions (KCl), methylene blue and petroleum products (engine oil, transmission fluid, diesel fuel) by samples of montmorillonite and kaolinite. The relationship between the value of the applied pressure (in the range from 0 to 700 MPa), fractional composition, specific surface and the microstructure of mineral particles was revealed. During the study, dynamics of changes in the content of the clay, dust and sand fractions in the clays under study was noted. It is established that an increase in clay compression to 700 MPa leads to a decrease in the content of clay fractions and an increase in the fraction of the dust fraction. Changes in the fractional composition occur more intensively in kaolinite clay than in montmorillonite clay. The pressure intervals were determined according to the intensity of the formation of the fractional composition of clays 0-200 and 200-700 MPa. Adsorption parameters of clays are determined. According to potentiometric measurements, it has been established that the ion-exchange capacity is higher in montmorillonite than in kaolinite with in respect to cations. The magnitude of kaolinite adsorption with respect to methylene blue decreases to a pressure of 200 MPa, which is caused by the content of the clay fraction, does not change significantly at pressures of 200-700 MPa. The adsorption rate of montmorillonite has a general tendency to increase. Adsorption indicators of clays with respect to methylene blue allow predicting the sorption capacity of the studied materials to petroleum products

Mathematical modeling of rocks fracture within local structures

Soil massif fracturing has a significant impact on change in engineering and geological conditions and, as a result, on stability of structures. Development of tectonic fracturing of local structures, taking into account the history of the process, its mechanism, resulting stresses in the massif and subsequent deformations of the rocks, led to a change in their structure, composition and strength characteristics, activation of hypergenesis and exogenous processes. The above circumstances require careful attention to identification of areas of increased fracturing, as the most dangerous in terms of risks during the construction of engineering structures. Field methods for assessing the fracturing of rock masses are laborious. It is not always possible to conduct instrumental surveys that allow solving the final problem – establishing patterns and sizes of damaged areas within local structures. The existing mathematical models for assessing fracturing, as a rule, are used to solve local problems: assessing the stability of developed pits, water content of rock masses, degree of fragmentation of individual blocks, etc. This information is not sufficient when assessing the areal distribution of weakened zones and clarifying their boundaries, since it does not take into account the history of the development of the structure, its parameters (dimensions, amplitude of the foundation block uplift, deformation properties of rocks). Aim. To develop a mathematical model of formation of the red-colored strata tectonic fracturing zones based on deformation criterion of destruction and mechanism of development of local structures. Results. The authors have developed a new mathematical model for predicting damage (fracturing) of terrigenous rocks of the red-colored strata that make up local structures, based on the mechanism of formation of local tectonic structures of the 3rd order and the deformation criterion of destruction. The paper introduces the mathematical dependencies that make it possible to predict the size (area) of taxa based on the data on the uplift amplitude of local structures. The results of the research can be used in assessing the fracturing of massifs composed of terrigenous rocks, and make it possible to judge the regularities in distribution of weakened zones within the entire massif being assessed

Possibilities of accounting the fracturing of Kashiro-Vereyskian carbonate objects in planning of proppant hydraulic fracturing

One of the effective methods of oil production intensification for heterogeneous Kashiro-Vereyskian clay-carbonate sediments of the Volga-Ural oil and gas bearing province is proppant hydraulic fracturing. Prospects of realization for this technology are considered in the article on the example of the Vereyskian development object of Moskud’inskoye field. Based on the analysis of rocks samples investigations of Vereyiskian sediments, lithological types of carbonate rocks differing in their structural features are distinguished. Tomographic investigations of rock samples were carried out, as a result of which the rock fracturing for some lithotypes was determined and studieds. Under natural geological conditions, depending on the degree of fracturing progression and technological conditions of development, these intervals may or may not be involved in well operation. When hydraulic fracturing is performed, potentially fractured areas that are not in operation can be successfully added to oil production. Based on analysis of hydrodynamic well investigations, the fracturing of the Vereyskian object of the Moskud’inskoye field was studied on the basis of the Warren-Ruth model. With the help of geological and technological indicators of development, prediction fracturing was obtained, which was used for the construction of the natural fracturing scheme. Areas of both pore and fractured reservoirs development were identified on the deposit area. As a result of statistical analysis, the influence of fracturing on efficiency of proppant hydraulic fracturing was determined. Based on the linear discriminant analysis, a statistical model for predicting the efficiency of proppant fracturing was developed. It was shown that in addition to natural fracturing, the results are most strongly influenced by specific proppant yield, formation pressure, permeability of the remote bottomhole zone and skin effect. Based on the developed model, prospective production wells of the Moskud’inskoye field are identified for proppant hydraulic fracturing

The Molecular and Mechanical Characteristics of Biomimetic Composite Dental Materials Composed of Nanocrystalline Hydroxyapatite and Light-Cured Adhesive

The application of biomimetic strategies and nanotechnologies (nanodentology) has led to numerous innovations and provided a considerable impetus by creating a new class of modern adhesion restoration materials, including different nanofillers. An analysis of the molecular properties of biomimetic adhesives was performed in this work to find the optimal composition that provides high polymerisation and mechanical hardness. Nanocrystalline carbonate-substituted calcium hydroxyapatite (nano-cHAp) was used as the filler of the light-cured adhesive Bis-GMA (bisphenol A-glycidyl methacrylate). The characteristics of this substance correspond to the apatite of human enamel and dentin, as well as to the biogenic source of calcium: avian eggshells. The introduction and distribution of nano-cHAp fillers in the adhesive matrix resulted in changes in chemical bonding, which were observed using Fourier transform infrared (FTIR) spectroscopy. As a result of the chemical bonding, the Vickers hardness (VH) and the degree of conversion under photopolymerisation of the nano-cHAp/Bis-GMA adhesive increased for the specified concentration of nanofiller. This result could contribute to the application of the developed biomimetic adhesives and the clinical success of restorations. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.075-15-2021-1351; Russian Science Foundation, RSF: 21-15-00026This work was funded by the grant of the Russian Science Foundation, grant number 21-15-00026. The access to scientific equipment and methodology was provided under the support of the Ministry of Science and Higher Education of Russia, Agreement No. 075-15-2021-1351