Diffusion Mode Research Articles

The physicochemical and adsorption properties of granular sorbents based on natural bentonite and modified sorbents based on it have been studied. It was found that modification of natural bentonite with iron (III) polyhydroxocations (mod. 1_Fe_5 GA) and aluminum (III) (mod. 1_Al_5 GA) by the "co-precipitation" method leads to a change in their chemical composition, structure, and sorption properties. It is shown that modified sorbents based on natural bentonite are finely porous (nanostructured) objects with a predominance of pores measuring 1.5-8.0 nm, with a specific surface area of 55-65 m2/g. Modification of bentonite with iron (III) and aluminum compounds by the "co-precipitation" method also leads to an increase in the sorption capacity of the obtained sorbents with respect to bichromate and arsenate anions and nickel cations by 5-10 times compared with natural bentonite. The obtained sorption isotherms were classified as Langmuir type isotherms. Kinetic analysis showed that at the initial stage the sorption process is controlled by an external diffusion factor, i.e. refers to the diffusion of sorbent from solution into a liquid film on the surface of the sorbent. Then the sorption process begins to proceed in a mixed diffusion mode, when it limits both the external diffusion factor and the internal diffusion factor (the diffusion of the sorbent to the active centers through the system of pores and capillaries). To determine the contribution of the chemical stage to the rate of adsorption of bichromate and arsenate anions and nickel(II) cations with the studied granular sorbents, kinetic curves were processed using the equations of chemical kinetics (pseudo-second-order model). As a result, it was found that the adsorption of the studied anions by modified sorbents based on natural bentonite is best described by a pseudo-second-order kinetic model. It is shown that the use of natural bentonite for the development of technology for the production of granular sorbents based on it has an undeniable advantage, firstly, in terms of its chemical and structural properties, it is easily and effectively modified, and secondly, having astringent properties, granules are easily made on its basis, which turn into ceramics during high-temperature firing. The result is a granular sorbent with high physical and mechanical properties. Since bentonite is an environmentally friendly product, the technology of recycling spent sorbents is also greatly simplified.

Diabetes is a chronic disease posing significant threats to global public health, where precision blood glucose monitoring serves as a cornerstone of effective disease management. While invasive blood sampling techniques remain prevalent in clinical practice, their inherent drawbacks—including patient discomfort and potential infection risks— have positioned non-invasive glucose detection as a major focus of scientific research. This study is based on near-infrared spectroscopy technology (780- 2500nm) to systematically analyze the characteristic absorption of hydrogen-containing functional groups, such as C-H and O-H in glucose molecules. The detection wavelength selection (1500-1800nm) and detection site (fingertip) were optimized, and the applicability of diffuse reflection and transmission detection modes was compared. In response to the complex and easily interfered characteristics of near-infrared spectral signals, an innovative BP neural network algorithm is introduced to construct a prediction model. By utilizing its powerful nonlinear mapping ability and adaptive learning characteristics, the accuracy of blood glucose concentration prediction is effectively improved. The research results indicate that this method has the advantages of noninvasiveness, convenience, and low cost, but it also faces technical challenges such as individual differences and environmental interference.

Collagen type II fibrils provide structural integrity to the articular cartilage extracellular matrix. However, the conditions that control the fibril radial size scale, distribution, and formation inside of dense networks are not well understood. We have investigated how surrounding elastic networks affect fibril formation by observing the structure and dynamics of collagen type II in model polyacrylamide gels of varying moduli. Cryogenic transmission electron microscopy (cryo-TEM) is used to image the fibril structure and is verified qualitatively with optical microscopy of fluorescently-tagged collagen within the gels. Using fluorescence correlation spectroscopy super-resolution optical fluctuation imaging (fcsSOFI), the diffusion dynamics of the collagen in low pH and neutral pH conditions are determined. Overall, the fibril bundle diameter and concentration were found to decrease as a function of gel modulus. The single fibril diameter remains constant at 30 nm within the gels; however, the diameter was found to be smaller when compared to in solution. Additionally, the mode of diffusion of the collagen triple helices changes within gel environments, decreasing the diffusion coefficient. Understanding the intricate relationship between network topology and collagen type II fibril formation is crucial in gaining deeper insights into the transport phenomena within complex acellular tissues that are necessary for the development of future therapeutic materials.

Production model of fractured horizontal wells in shale gas reservoirs considering different gas diffusion mode

Spreading processes on top of active dynamics provide a novel theoretical framework for capturing emerging collective behavior in living systems. I consider run-and-tumble dynamics coupled with coagulation/decoagulation reactions that lead to an absorbing state phase transition. While the active dynamics does not change the location of the transition point, the relaxation toward the stationary state depends on motility parameters. Because of the competition between spreading dynamics and active motion, the system can support long-living currents whose typical time scale is a nontrivial function of motility and reaction rates. Because of this interplay between time-scales, the wave front propagation qualitatively changes from traveling to diffusive waves. Moving beyond the mean-field regime, instability at finite length scales regulates a crossover from periodic to diffusive modes. Finally, it is possible to individuate different mechanisms of pattern formation on a large time scale, ranging from the Fisher-Kolmogorov to the Kardar-Parisi-Zhang equation.

Production model of fractured horizontal wells in shale gas reservoirs considering different gas diffusion mode

The diffusion dynamics of polymer chains within a narrow slit formed by two patch-patterned surfaces is investigated utilizing Langevin dynamics simulations. These surfaces feature periodically arranged attractive patches of size L and period d, with a staggered configuration of (0.5d, 0.5d) offsets along the x and y axes. When d is fixed, the polymer chain exhibits normal diffusion over long time scales, with the translational diffusion coefficient Dxy gradually decreasing to zero as L increases. Notably, our findings reveal four distinct diffusion modes: free-diffusion mode for L ≤ L1, where the polymer chain is mainly in a desorption state; adsorption-desorption mode for L1 < L ≤ L2, involving transitions from a single-patch adsorption state to a desorption state; exchange-patch mode for L2 < L ≤ L3, where the polymer chain switches between a single-patch adsorption state and an upper-lower double-patch adsorption state by exchanging patches; and nondiffusion mode for L > L3, where the polymer chain is primarily in a pinned state. Furthermore, as the patch attraction strength εps increases, Dxy decreases due to an increase in the adsorption time of the polymer chain. Simultaneously, critical patch size thresholds L1, L2, and L3, exhibit a decreasing trend. These observations highlight the significant influence of the confining slit and patch properties on the diffusion behavior of polymer chains.

The Japanese concept of “ kokoro no kea” (care for the heart/mind) plays a crucial role in shaping disaster mental health response systems. Following the 2011 Great East Japan Earthquake and tsunami, and the subsequent nuclear plant accident, the government quickly implemented kokoro no kea initiatives. However, many locals reported reluctance to seek support from kokoro no kea teams. This article explores therapeutic governance in response to these disasters, a multifaceted, disavowed, and diffusive mode of governing. It highlights how recovery politics emphasized solidarity—referred as “kizuna” (social bonds)—while also gendering and pathologizing women’s fears and anxieties regarding radiation exposure. Through a narrative review of ethnographic studies, this analysis demonstrates that kokoro no kea is not simply a static post-disaster mental health and psychosocial support system; rather, it is an open, fluid, and evolving process where diverse actors—such as politicians, men, women, health professionals, and religious practitioners—interact with socio-political forces and cultural values, creating unique pathways for individuals and communities to foster connections, build trust, and nurture resilience in coping with psychological pain and loss.

In this paper, the results of the study of photoelectric properties of silicon with binary compounds GexSi1-x are presented. The selection of the impurity atom of germanium for introduction into silicon was justified by the fact that those impurities have unlimited solubility and, depending on the technological modes of diffusion, can be located in the nodes or between the nodes of the crystal lattice of silicon. A high solubility of germanium atoms in silicon allows the formation of GexSi1-x compounds on the surface and near the surface of silicon. To obtain silicon doped with impurity atoms of germanium, the original monocrystalline silicon of the KEF-100 brand was used. Doping of impurity atoms of germanium into silicon was carried out according to the developed low-temperature two-stage diffusion technology. The results of the studies allowed to determine the thermodynamic conditions (Т = 1100÷1250°С and t = 5÷20 h) and technological modes of low-temperature two-stage diffusion of impurity atoms of germanium, which made it possible to obtain a material with binary compounds GexSi1-x on the surface and near-surface of silicon with given electrophysical parameters. From the results of the study of the concentration distribution of the formed binary compounds GexSi1-x in silicon, it was established that compounds with the maximum concentration were formed on the surface, and their concentration decreased with depth into the volume of silicon. From the spectrum of the X-ray energy dispersive microanalysis, it was established that the compounds GexSi1-x formed in silicon lead to a change in the forbidden zone width of the original material. It is shown that the change in the forbidden zone width of the original silicon due to the formation of binary compounds GexSi1-x changes one of the fundamental parameters of the material, which, in turn, leads to an expansion of the spectral region of sensitivity, which is typical in the development of efficient photocells with a wide range of solar radiation absorption.

Purpose. The analysis and identification of regularities of the combustion process of magnesium particles in active gaseous products of thermal decomposition of nitrate-containing oxidizers and additives of the specified substances for determining the fire-hazardous properties of pyrotechnic mixtures under external thermal conditions . Methods. Modern methods of physical and chemical analysis: thermocouple methods of temperature measurement (tungsten-rhenium thermocouples were used); non-contact methods of recording the beginning and end of the burning of metal particles (temperature indicators, photosensitive elements, etc.); film shooting methods (film camera “Konvas-auto” (shooting speed 30 frames/s)) and methods of micro-filming SKS-1M film camera (shooting speed 3000…5000 frames/s)) of the burning process of individual metal particles; methods of X-ray structural and micro-X-ray spectral analysis (MRSA) for chemical analysis. The results. Data on the combustion of magnesium particles in active gaseous products of thermal decomposition of nitrate-containing oxidizers, organic and inorganic substances are systematized and summarized. It was found that the combustion of magnesium particles is highly complex, occurring through a diffusion mechanism influenced by a variety of factors. Additionally, the combustion of magnesium ribbons in a mixture of oxygen and inert gases occurs in eight distinct regions, each with characteristic flame features that depend on oxygen concentration and external pressure. It was established that magnesium particles burn in oxygen-containing media in the diffusion mode with the formation of a bright glow zone, the radius of which increases with increasing oxygen concentration and external pressure. Scientific novelty. For the first time, regularities of the combustion process of magnesium particles in active gaseous products were established (О2, О2 + N2, air, СО2, water vapor, etc.) thermal decomposition of nitrate-containing oxidants (О2, О2 + N2, air, СО2, water vapor etc.) and additives of organic substances (paraffin, stearin, iditol, thiocol, etc.) and inorganic substances (metal fluorides and oxides, etc.) to determine the fire-hazardous properties of pyrotechnic mixtures under conditions of external thermal effects. Practical significance. The theoretical and experimental results, presented as mathematical models and a database of experimental data, demonstrate the influence of technological parameters of mixture charges on the critical modes of explosive combustion under external thermal conditions (elevated temperatures, external pressures, etc.). These results enable the optimization of technological parameters (e.g., component ratios, dispersion of metallic fuel) during product manufacturing, increasing ignition temperatures and reducing the likelihood of fire-explosive destruction during storage, transportation, and product use under thermal conditions. Key words: pyrotechnic multi-component nitrate-metallized mixtures, fire safety, metal fuels, combustion processes.

Abstract The work is aimed at revealing the influence of volume recombination on the formation of plasma parameters on the example of a diffuse and constricted positive column of a DC discharge in argon depending on the discharge current at pressures of 100–300 Torr·cm. At a qualitative level, the limiting transitions from the diffusion mode to the recombination mode of discharge maintenance are analyzed, which lead either to a rectangle-shaped radial profile of charged particles (arc discharge) or to a compressed profile (constricted discharge). Valuable information about the processes occurring in the plasma volume can be obtained from the ion current flowing toward the wall of the discharge tube since it is determined as a difference between the volume ionization and recombination. Based on a collision-radiative model, the ion current towards the tube wall was calculated and compared with the experimental results of probe measurements. In a diffuse discharge (low discharge current) a satisfactory agreement between the theory and experiment is observed. After the abrupt transition to the constricted regime (high discharge current), the theoretical values become strongly underestimated, and not able to describe the experimental data. The reasons for these discrepancies are analyzed. It is shown that the photoemission from the surface of the probe under the action of resonance photons gives an additional ion probe current which allows eliminating the discrepancies between the theory and experiment. Based on the Holstein–Biberman equation, the influence of the resonance radiation trapping on the discharge properties is revealed. The account of radiation trapping improves the agreement between the theory and experiment, including the values of the critical discharge currents at which the constriction occurs.

The coal–oxygen composite reaction is a complex physicochemical reaction process, and different heating rates have a great influence on this reaction. In order to reveal the influence of different heating rates on the coal–oxygen composite reaction of coking coal, the TG-DSC experimental method was adopted to analyze the hysteresis effect of the characteristic temperature, inflection point temperature, and peak temperature under different heating rates. Furthermore, the KAS method was employed to calculate the apparent activation energy, and the Málek method was utilized to infer the most probable mechanism functions and determine the compensation effects at different stages of the coal oxidation process. The results show that with an increase in heating rate, the temperature values corresponding to each characteristic temperature point increase, the characteristic temperature exhibits a hysteresis phenomenon, and the heat flow rate and heat flux rate also show an increasing trend. The apparent activation energy gradually increases in Stages II and III, with a maximum value of 198.7 kJ/mol near the ignition point T3, which first increases and then gradually decreases in Stage IV, where the maximum value is around the temperature point T4 of the maximum mass loss rate, which is 170.02 kJ/mol. The variation trend in the pre-exponential factor is consistent with the apparent activation energy, and the dynamic compensation effect is greater in Stage IV. The three different oxidation stages have different mechanism functions: a three-dimensional diffusion mode is present in Stages II and III, which is ultimately transformed into an accelerated form α-t curve with E1 and n = 1 in Stage IV.

Characterization of microstructure and moisture distribution evolution of concrete using AC impedance spectroscopy

The present study proposes the use of Near-Infrared (NIR) spectroscopy as a rapid method for estimating the growth of Spirulina platensis cultures, avoiding any sample manipulation or pretreatment. NIR spectroscopy in diffuse reflectance mode was used on culture volumes as received, with Principal Component Analysis (PCA) and Partial Least Squares (PLS) linear regression, for developing the calibration model in the wavelength range of 1000-2500 nm, in order to choose the appropriate wavelength to estimate the growth of the microalga. The local reflectance maximum at 1062.6 nm, connected with reduced water absorption and scattering effects by the microalga, was identified from PCA as the positive peak in the first loading plot, correlating diffuse reflectance with dilution levels. The calibration curve of diffuse reflectance at 1062.6 nm in response to dilution presented strong linearity, supported by a coefficient of determination (R2) of 0.995. Cross-validation of NIR spectra with a S. platensis culture confirmed the method's reliability, showing that the growth follows an exponential pattern. The study shows that diffuse reflectance NIR spectroscopy can be used for the rapid monitoring of Spirulina platensis growth.

This work presented the results of an experimental study of dynamics of emulsion complex composition droplets under laser irradiation. The oil-in-water emulsion consisted of liquid paraffin droplets containing magnetite nanoparticles and was placed in an aqueous solution of the surfactant. The magnetite nanoparticles had characteristic dimensions of 10−8 m, which correspond to the dimensions of molecular motors in living cells. For all emulsion droplets, motion in transitional and normal diffusive modes was observed. The effective kinetic temperature of emulsion droplets was 3.5 × 103 eV and was exceeded the temperature of thermal motion of the medium molecules, 0.03 eV. Experimentally observed active Brownian motion of emulsion droplets was a result of intra-droplet motion of magnetite nanoparticles absorbing laser irradiation. Laser irradiation caused the magnetite nanoparticle heating, which generated a thermophoretic force. As a result of viscous friction forces, the nanoparticles transferred momentum to the emulsion droplet, causing its motion.

Base excision repair is the main pathway involved in active DNA demethylation. 5-formylcytosine and 5-carboxylcytosine, two oxidized moieties of methylated cytosine, are recognized and removed by thymine DNA glycosylase (TDG) to generate an abasic site. Using single molecule fluorescence experiments, we study TDG in the presence and absence of 5-formylcytosine. TDG exhibits multiple modes of linear diffusion, including hopping and sliding, in search of base modifications. TDG active site variants and truncated N-terminus, reveals these variants alter base modification search and recognition mechanism of TDG. On DNA containing an undamaged nucleosome, TDG is found to either bypass, colocalize with, or encounter but not bypass the nucleosome. Truncating the N-terminus reduces the number of interactions with the nucleosome. Our findings provide mechanistic insights into how TDG searches for modified DNA bases in chromatin.

Objective: The objective of this study is to find a method for synthesizing uncharged polystyrene latex particles whose surface can be easily modified. Theoretical basis: The main method of latex synthesis is emulsion polymerization. Latexes for a specific purpose can be obtained by polymerization in heterogeneous monomer-water systems, without the use of emulsifiers, both with intensive mixing of the system and under static conditions. In this work, polymerization was carried out without the use of emulsifiers in a static monomer-water system. Method: To achieve the set goal, the possibility of obtaining latex particles using a hydrophobic initiator - ditrile of azoisobutyric acid - was investigated by carrying out polymerization in a diffusion mode in a three-phase system monomer - water - initiator. Results and discussion: The results of the study showed that the latex obtained in the three-phase system is stable. It is assumed that the stability is due to the presence of hydroxyl end groups groups of polymer molecules on the surface of the latex particles, which are formed as a result of the reaction of the initiator with water and initiate polymerization. The synthesized latexes retained stability for a year. Practical value: Latexes can be used in all those areas of science and technology where the absence of a charge on the surface of latex particles is required. Originality/value: The originality of the work lies in the fundamental simplicity of the synthesis and the unambiguity of the results obtained.

Visitor education plays a crucial role in the knowledge diffusion process in outdoor recreation and nature-based tourism. It entails sharing information, experiences, and insights with visitors to enhance their understanding and appreciation of the natural environment. Our methodology for investigating the diffusion of ecological civilization knowledge in tourism destinations involves constructing a knowledge diffusion network model. In this model, scenic spots, tourists, and the public are defined as network nodes, with the communication channels between them representing the edges of the network. By constructing a scale-free complex network, the knowledge diffusion mode of scenic spots can be depicted. The layer of resource supply node consists of different scenic spots, forming the core nodes set for knowledge diffusion in the tourism industry. This research aims to further explore the social and economic value of the tourism areas' ecological civilization knowledge diffusion, as well as analyze the path, quantity, and cost of knowledge diffusion. by analyzing this knowledge diffusion network model, insights into the effectiveness and impact of visitor education in promoting ecological civilization and sustainable practices in tourism destinations can be gained. Overall, this approach provides a theoretical framework for investigating and comprehending the knowledge diffusion process in Tourism Destination-Public ecological civilization, thereby shedding light on the social and economic benefits that can be derived from sustainable tourism practices.

As an effective theory, relativistic hydrodynamics is fixed by symmetries up to a set of transport coefficients. A lot of effort has been devoted to explicit calculations of these coefficients. Here we adopt a more general approach, deploying bootstrap techniques to rule out theories that are inconsistent with microscopic causality. What remains is a universal convex geometry in the space of transport coefficients, which we call the hydrohedron. The landscape of all consistent theories necessarily lies inside or on the edges of the hydrohedron. We analytically construct cross-sections of the hydrohedron corresponding to bounds on transport coefficients that appear in sound and diffusion modes’ dispersion relations for theories without stochastic fluctuations.

This paper presents the Machine Learned Diffusion Coefficient Estimator, a comprehensive machine learning framework designed to predict diffusion coefficients in impure metallic (IM) and multi-component alloy (MCA) media. The framework incorporates five machine learning models, each tailored to specific diffusion modes: (1) impurity and (2) self-diffusion in IM media, and (3) self, (4) impurity, and (5) chemical diffusion in MCA media. These models use statistical aggregations of atomic descriptors for both the diffusing elements and the diffusion media, along with the temperature of the diffusion process, as features. Models are trained using the random forest and deep neural network algorithms, with performance evaluated through the coefficient of determination (R2), mean squared error (MSE), and uncertainty estimates. The models within this framework achieve an impressive R2 score above 0.90 with MSE less than 10−16 m2/s, demonstrating high predictive accuracy and reliability for diffusion coefficient.