Exchange Process Research Articles

Sintering of different silica aerogels

This work reports on isothermal sintering experiments, conducted with silica aerogel samples in a broad density range (∼0.025–0.277 kg/m3) made by the same process by varying the solvent-to-sol ratio, as well as samples made by different formulations used by several aerogel manufacturers. The latter comparison is deficient in the literature. Low-density (<0.05 kg/m3) aerogels were found to be significantly more resilient to sintering, which is consistent with established sintering theories. Unexpectedly large variability in the susceptibility to sintering was observed in similar density (∼0.1 kg/m3) aerogels made by different formulations and by different producers. All material made by utilizing a CO2 solvent exchange step prior to supercritical drying exhibited effects attributable to residual original solvent in the micropores. This alludes to an incomplete solvent exchange process. The materials were examined in the context of devising a methodology for producing an ultra-pure silica aerogel, a substance free of organic constituents, intended to serve NASA life detection mission needs.

Modeling of Graded-Index Raman Fiber Amplifiers with Pump Depletion

Graded-index (GRIN) fibers are often used for making high-power Raman amplifiers. We employ numerical and semi-analytical techniques to model such amplifiers and include not only the signal’s amplification and pump’s depletion but also various nonlinear interactions between the signal and pump beams and the self-imaging effects within the GRIN fiber. We solve the coupled nonlinear equations of the pump and signal beams numerically. We also employ the variational technique to obtain simpler equations that can be solved much faster than the full model and still agree with it in most cases of practical interest. We discuss the evolution dynamics of the pump and signal beams, along with a novel process of energy exchange between the two beams because of self-imaging inside the GRIN fiber. The dependence of the signal’s amplification on various input parameters is analyzed in detail to optimize the device’s design and enhance the signal’s amplification for a given pump power and fiber length. Based on our analysis, we establish a resonant condition for the maximum energy transfer from the pump to the signal being amplified. We further show that the periodic self-imaging of the pump and signal beams inside a GRIN fiber leads to higher output powers compared to step-index fibers.

MATHEMATICAL MODELING OF THE PROCESS OF SEPARATION OF MIXTURES BY LIQUID EXTRACTION

While designing liquid-phase extraction processes, one of the main conditions is to determine the kinetic characteristics of the exchange processes necessary to determine the flows and masses of the components. Existing mass transfer models describe mass transfer processes on a semi-empirical and empirical basis with a limited range of applications, simplifying the real picture in most cases. In this regard, the development of models that more widely describe the processes of liquid-phase extraction and allow their application is considered one of the important tasks. Based on the generalization of the Chilton-Colborne hydrodynamic analogy in gradient flows and further development of the Landau-Levich boundary layer model, a mathematical model has been developed to determine the mass transfer coefficients in the extraction process in continuous and dispersed phases using minimal experimental data obtained at the stage of hydrodynamic studies

Assessment of the impact of intensification of heat exchange processes in heaters on power unit efficiency

In various spheres of modern industry, including power engineering, the issue of low efficiency of operation of heatexchange equipment, where condensation of vapour-gas media occurs, is a significant concern. It is known that one of the effective ways of solving this problem is intensification of heat exchange processes by transitioning from the traditional film condensation mode to the droplet condensation mode. A promising and technically straightforward way to achieve the droplet mode of condensation is a method based on the treatment of heat-exchange surfaces using a surfactant – octadecylamine (ODA). The analysis of studies, in which results of experimental research and industrial implementation are given, has shown that application of the specified method in conditions of condensation of water steam promotes formation of a stable droplet mode of condensation; as a result, the heat transfer coefficient on the steam side can more than double.Equally important and interesting is the question of how the efficiency of heat exchangers impacts the overall efficiency of complex systems, in which they operate. In this study, we examined the effect of the operational efficiency of network and regenerative heaters on the energy efficiency and economic performance of a power unit based on steam turbine unit T-110-12,8-3 operating in the heat recovery mode. To this end, we calculated the thermal scheme under various operating conditions of these heat exchangers and determined several key efficiency indicators, including the fuel heat utilisation factor (HUF) and electrical efficiency (EE). It is revealed that intensification of heat-exchange processes by a factor of 2 in horizontal delivery water heaters (HDWH) or in low-pressure heaters (LPH) significantly enhances the efficiency indicators of the power unit as a whole. At the same time, as the analysis of calculation results showed, the greatest benefits are realized when this measure is implemented in HDWH.

Optimization of Liquid Phase Catalytic Exchange Process for Hydrogen Isotope Separation Using Orthogonal Experiment Design

Optimization of Liquid Phase Catalytic Exchange Process for Hydrogen Isotope Separation Using Orthogonal Experiment Design

Innate Immunity in Rice: A Defense Against Bacterial Leaf Blight

Rice (Oryza sativa L.) is one of the major staple food crops of the world and sustainable rice production is important for ensuring global food security. Throughout the growing season, a variety of pathogens including fungi, bacteria, viruses, and nematodes, infect different parts of the crop resulting in yield loss. Bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the major limiting factors in rice production. Being a vascular pathogen, X. oryzae pv. oryzae interferes with a range of physiological and biochemical exchange process in rice. The earlier the pathogen infection, more will be the loss and grain quality is also severely affected due to infection. The spread of the pathogen is too rapid in the favourable climatic conditions. The disease results in 20 to 30 per cent annual loss in rice production and under severe conditions, the yield loss goes up to 80 per cent. Plant pathogens employ different ways to attack host plants and impair plant growth and reproduction. Unlike vertebrates, plants lack mobile immune cells and an adaptive immune system. Plants mainly rely on two interconnected tiers of the innate immune system to perceive and respond to pathogen infection. This innate immune system or basal resistance mediated by a repertoire of Resistance or R genes in plants acts as the first line of pre-formed and inducible defenses that protect the host plants from large number of pathogens. Over the years, extensive investigation on the molecular interactions between rice and Xanthomonas oryzae pv. oryzae has made impressive progress in understanding the molecular basis of rice innate immunity against bacterial leaf blight. Improving plant immunity has been considered as one of the best choices available for achieving economical and sustainable management of bacterial leaf blight in a durable manner. In this review, we summarize the molecular basis of two tiered innate immune system including PAMP triggered immunity (PTI) and Effector triggered immunity (ETI) as well as R genes involved in rice - Xanthomonas oryzae pv. oryzae interaction.

Reduction in Temperature-Dependent Fiber-Optic Gyroscope Bias Drift by Using Multifunctional Integrated Optical Chip Fabricated on Pre-Annealed LiNbO3

The refractive index change obtained after annealed proton exchange (APE) in lithium niobate (LiNbO3) crystals depends on both the proton exchange process carried out in hot acid and the structure of the crystals. In devices produced by the APE method, dislocations and lattice defects within the crystal structure are considered to be primary contributors to refractive index discontinuities and waveguide instability. In this study, the effects of pre-annealing LiNbO3 crystals at 500 °C on multifunctional integrated optical chips (MIOCs) were investigated through interferometric fiber-optic gyroscope (IFOG) system-level tests. It was observed that the pre-annealing process resulted in an improvement in the optical throughput of MIOCs (from %34 to %51) and the temperature-dependent bias drift stability of the IFOG (from 0.031–0.038°/h to 0.012–0.019°/h). The angle random walk (ARW) was measured as 0.0056 deg/√h.

МЕДИКО-БІОЛОГІЧНІ ОСНОВИ ВПЛИВУ ФІЗИЧНИХ ВПРАВ НА ЗБЕРЕЖЕННЯ ЗДОРОВ’Я СТУДЕНТСЬКОЇ МОЛОДІ

The article examines the medical and biological basis of the influence of physical exercises on the health of student youth. Literary sources related to the topic of the study were analyzed. The problem is described in its general form, which concerns the way of life of modern student youth. It is noted that only in-depth knowledge of the medical and biological influence will help to form students' desire and motivation to engage in physical exercises, as well as to observe the basics of a healthy lifestyle. The morpho-functional changes occurring in the human body during physical exercises are revealed. The division of the organism's reserves into biological and social is presented. The functional effects of exercises on life expectancy is described. A comparative analysis of the influence of motor activity and hypokinesia on the human body was carried out. The basics of adaptation of individual body systems to physical exertion are revealed, namely: changes in the composition and physicochemical properties of blood and the circulatory system, functional effects of adaptation of the respiratory system, features of adaptation of the digestive and metabolic systems, as well as functional effects of adaptation of neurohumoral regulation systems. In the process of research, it was concluded that it is difficult to overestimate the medical and biological impact of physical exercises on the process of preserving the health of student youth, since physical activity affects the human body in a complex way, on all its systems, processes of exchange and accumulation of functional reserves. It was concluded that with the help of physical exercises you can achieve many positive effects and affect the overall life expectancy of a person. Prospects for further research in this direction are seen in determining the level of awareness of student youth in the issues of medical and biological bases of the influence of physical exercises on preserving their own health, as well as finding new approaches for working with students in this direction in order to achieve the formation of sustainable motivation for physical activities exercises and adherence to the basics of a healthy lifestyle.

Thermal Characteristics of the Extreme Cases of Tropopause Over the Tropics

ABSTRACTThe anomalous variability of extreme cases of the tropical tropopause provides insight into the stratosphere‐troposphere exchange process crucial for understanding climate change. The present study analyses the extreme variability of the tropopause and its thermal structure over the tropics using GPS radio occultation data over the period 2006–2019. The extremely cold and warm tropopauses and extremely high and low tropopauses are identified based on the cold point tropopause temperature and height, respectively, when their values exceed two standard deviations with respect to their climatological means. The analyses revealed frequent occurrence of extreme cases of tropopause over the Atlantic Ocean compared to the Western Pacific Ocean. Individually, extremely warm and low cases occur more frequently over the subtropics, while extremely cold and high cases occur frequently over the deep tropics. These extreme cases pose different thermal structures bounded within the extremely low and high tropopauses throughout the tropics. The height difference between the extremely high and low tropopause cases is wider over the Atlantic Ocean and adjoining areas compared to the western Pacific Ocean. The temperature difference between the extremely warm and cold tropopause cases is higher in the Atlantic, Central Pacific, and Indonesian regions compared to the American, Indian Ocean, and western Pacific Ocean regions. The relationship between the El Niño Southern Oscillation (ENSO) phases and extreme tropopause cases is also investigated which reveals a higher occurrence of extremely high tropopause cases during the El Niño phase while low tropopause cases during the La Niña phase. Our analysis also revealed the thermal patterns of the extreme cases characterising colder and sharper tropopause over the convective regions compared to subsidence regions.

Unveiling the potential of direct synthesized PbS CQD ink based solar cells through numerical simulation

Studies on lead sulfide-PbS quantum dot-QD based solar cells have gained considerable attention in recent years. A direct synthesis-DS method has emerged that makes it possible to obtain PbS ink in a single step by eliminating complex synthesis and ligand exchange processes, thus reducing the production cost and time. However, the limited number of studies on cells obtained with this method obscures the high potential of this technique. In this study, various electron-ETL and hole transport layers-HTL were systematically brought together in the SCAPS-1D environment to determine the architecture of the cell with record performance. A photoconversion efficiency-PCE of over 20% was achieved with a cell in which n-type DS PbS inks were combined with TiO2 ETL and MoO3 HTL. Moreover, we found that p-type DS PbS inks have a much higher potential than n-type inks, with a PCE of up to 36%, and most importantly, they are more resistant to increased defect density. We believe that this study, in which the device architecture for DS PbS inks was optimized and structured for the first time and the importance of p-type DS PbS inks was emphasized, will shed light on future studies in the field of solar cell technologies.

Система поддержки принятия решений при выборе типа кожухотрубчатого теплообменника

The article discusses the development of an ontology for the subject area using a shell-and-tube heat exchanger as an example. This ontology enables the selection of the type of heat exchanger (fixed tube sheets, compensator, U-shaped tubes) based on the coolant (ammonia, methanol), heat exchange process conditions (pressure, temperature), and the geometric parameters of the heat exchanger (device diameter). The ontology is designed for use in the hardware design phase of chemical-engineering systems. A functional model is presented that outlines the key stages and information flows in the hardware design of chemical-engineering systems. Each design stage utilises an information model, converting the input information flow into an output one. The article describes an information model for selecting the type of heat exchanger, represented by production rules, which includes operators for determining the material of the heat exchanger elements based on the coolant, material-specific design, and the type of heat exchanger. A prototype of the described information model is implemented in the Protégé ontology editor. The ontology and an example query for determining the type of heat exchanger for a given coolant and heat exchange process parameters are provided. The data for creating the ontology are sourced from regulatory design documents. The article concludes that an ontological approach is feasible for creating "smart" design documents, including standards and technical specifications comprehensible to both humans and computers.

STRUCTURAL AND FUNCTIONAL ASPECTS OF POLITICAL COMMUNICATION IN THE CONTEXT OF MODERN SOCIAL DEVELOPMENT

The article highlights the structural and functional features of political communication as a process of communicative interaction in the political sphere in the conditions of modern social development. It was determined that political communication is a communicative process of mutual exchange of political information and broadcasting of political discourse among political subjects, state administration bodies, civil society, aimed at achieving consensus in making political and managerial decisions, legitimizing power and maintaining the stability of the democratic political system through means mass communication, Internet social networks, informal contacts, etc. The leading functions of political communication in terms of its structural elements are distinguished: 1) subjects of political communication: citizens, state authorities and management, political parties, movements and associations, civil society institutions, associations and groups of users of social networks on the Internet etc; 2) feedback between the subjects of political communication, acting as a communicative interaction that takes on different forms of information exchange; 3) information message as a relevant political discourse; 4) channels and means of information transmission and two-way communication between subjects of political communication.

A modular, human body-mimicking phantom with active thermoregulation capabilities for validation and verification of convective hyperthermia devices

Objectives This study aims to design and fabricate a modular phantom for hyperthermia applications, addressing interpatient variability in thermal regulation mechanisms like sweating rate, metabolic heat production, and blood redistribution. Materials & methods The phantom can be constructed in various weights and dimensions by connecting identical units. Each unit consists of an agar-based block, an ethyl cellulose-based top layer, a heat source, deep and superficial water circulation, and a sweating mechanism. Agar and ethyl cellulose gels mimic the thermal properties of human tissues and fat respectively. The blocks are wrapped in PVC foil to prevent water evaporation. A heating wire, coiled around an embedded aluminum tubing simulates metabolic heat production. A superficial water circulation mimics skin capillaries. A water pump ensures a steady flow rate throughout the tubing system. Sweat production is simulated using a water pump and perforated tubing. A programmed controller maintains core temperature in a normal operating mode and simulates an anesthetized patient in anesthesia mode. Results Temperature uniformity and regulation were assessed under varying environmental conditions. The phantom effectively regulated its core temperature at 37.0 °C +/- 0.7 °C with an ambient temperature ranging between 21 °C and 30 °C. Activating the water circulation reduced the maximum temperature gradient within the phantom from 4.70 °C to 1.92 °C. Conclusion The versatile phantom successfully models heat exchange processes. Its thermal properties, dimensions, and heat exchange rates can be tuned to mimic different patient models. These are promising results as an effective tool for hyperthermia device validation and verification, representing human physiological responses.

Rapid deep learning prediction model using satellite imagery for radiation accident Announcement system in Serbia

Radioactivity environmental monitoring with the help of the Radiation Accident Announcement System (RAAS) established in the Republic of Serbia is of vital importance for rapid response in the event of intervention dose values being reached such as Operational Intervention levels (OILs). There are cases of impossibility of using a ground-based model in order to predict the transport and spread of radiation during a nuclear accident such as the one in the Fukushima Daiichi nuclear power plant 2011. Modern technology has made it possible to use machine learning models with remote sensing data in addition (or an alternative) to atmospheric models with ground data collection methods. Deep learning (DL) model was developed and trained on a satellite-based cloud fraction dataset to forecast diurnal cloud drift. By forecasting the movement of clouds that are potential carriers of radioactive materials, decision-makers can provide an adequate response with an Action Plan in the case of nuclear and radiation accidents and incidents. Designed Application Programming Interface (API) has been developed and integrated between the DL model and the RAAS. In this way, the monitoring, data sharing and exchange processes were automated in order to trigger the DL model when an OILs value of 1 μSv/h is reached. The hyperparameter optimization process of the DL model was done with grid search and Particle Swarm Optimization (PSO) to achieve maximum performance on the data in a reasonable amount of time. The evolution metrics to monitor and measure the performance of the DL model were cosine similarity (CS) and structural similarity (SS) with the best score of 0.78282 and 0.27063 for grid search, respectively, while 0.27065 and 0.78282 for PSO, respectively. It can be concluded that remote sensing imagery with DL model is an alternative approach against a ground-based forecasting system, and is able to predict in near real-time independently of ground network system and data.

Initial temperature conduction process and fracture response of rock impacted by ultra-low-temperature fluid: A case study of polymethyl methacrylate

Injecting ultra-low-temperature fluids, such as liquid carbon dioxide (CO2) and liquid nitrogen (LN2), into deep, low-permeability reservoirs for fracturing is an emerging waterless fracturing technology. When these fluids enter the reservoir, they rapidly exchange heat with the fracture walls, triggering intense cold shock, which influences fracture development. Although many scholars have studied the effects of nitrogen freezing and thawing on coal seams, the initial thermal exchange and cold shock process when LN2 first enters the rock mass remains unclear. This paper uses the visualizable material polymethyl methacrylate (PMMA) as the research object, conducting low-temperature impact experiments under different preset temperatures (20 °C, 40 °C, 60 °C, and 80 °C) to investigate the impact of thermal exchange during cold shock on PMMA fracturing. The results show: (1) During LN2 impact, PMMA's temperature changes in three stages: slow cooling (micro-cracks initiation), rapid cooling (formation of long fractures), and temperature recovery (crack formation completion). (2) In prolonged impacts, PMMA temperature decreases linearly, while in short-term cyclic impacts, temperature decreases exponentially with faster recovery, increasing the likelihood of micro-cracks formation. (3) Temperature differences have a dual effect on crack formation and propagation: they significantly enhance internal thermal stress, leading to rapid micro-cracks initiation and expansion, while also causing uneven temperature gradients in the crack propagation region, shifting fracture modes from tensile to complex composite failures and promoting secondary crack formation. However, a significant temperature differential may result in the development of a singular crack propagation path, hindering the formation of complex fracture networks. These findings offer theoretical insights into fracture network formation in waterless fracturing of low-permeability reservoirs.

A novel approach for immobilizing Ag/ZnO nanorods on a glass substrate: Application in solar light-driven degradation of micropollutants in water

One of the main challenges in applying photocatalysts for water treatment is the complex separation and recycling process. In this study, we developed highly stable, porous zinc oxide nanorods (ZnO NRs) immobilized on glass vials using a solvent exchange process (SEP) and hydrothermal calcination. Key parameters, including oleic acid concentration and hydrothermal growth time, were optimized to maximize the active surface area, significantly enhancing photodegradation performance. Under the best conditions, ZnO NRs-coated vials achieved nearly 100% degradation of sulfamethoxazole (SMX) in 10 h of simulated solar irradiation. Depositing silver nanoparticles on the surface of ZnO NRs (Ag/ZnO NRs) further improved performance, reducing degradation time to 4 h and increasing photocatalyst stability. The Ag/ZnO NRs-coated vials, optimized with an Ag precursor concentration of 0.05 M, also demonstrated high degradation rates (>99%) for eight organic micropollutants at environmentally relevant concentrations over multiple reuse cycles and with minimal metal leaching. This study presents an innovative, tunable method for immobilizing photocatalysts on glass substrates, offering high surface area, excellent photocatalytic activity, and mechanical properties, making it highly suitable for water treatment applications.

Artificial neural network-based computational heat transfer analysis of Carreau fluid over a rotating cone

Heat transport in a dynamically rotating cone immersed in a Carreau fluid is the subject of this investigation. The fluid is non-Newtonian, admired for its characteristics, and extensively utilized in numerous industrial domains. The study investigates the interplay between buoyancy and centrifugal forces within an analytical framework. The study employs sophisticated mathematical methods, including similarity transformations, to convert governing partial differential equations into nonlinear ordinary differential equations. These equations are then solved using the shooting method, a numerical technique that solves a boundary value problem by iteratively adjusting the initial conditions until the boundary conditions are satisfied. We employ an artificial neural network algorithm with backpropagation Levenberg–Marquardt scheme to analyze the heat transfer mechanism quantitatively. In conjunction with the shooting mechanism, we will use numerical simulation with an artificial neural network algorithm, namely the backpropagation Levenberg–Marquardt scheme. The results prove the enormous influence of centrifugation and buoyancy on complex fluid dynamics and heat exchange processes. Some critical parameters that govern the convective heat transport process are the Nusselt number, the Reynolds number, the Grashof number, and the fluid and cone rotational velocities. The research validates the requirement of considering non-Newtonian complexity and viscous dissipation when investigating heat transfer dynamics and fluid flow, facilitating more accurate expectations and improved efficiency in various industrial processes.

Au/Ag@ZnS yolk-shell photocatalysts enhanced with noble metals and hyaluronic acid for efficient hydrogen production in rheumatoid arthritis therapy

Rheumatoid arthritis, characterized by the abnormal proliferation of synovial cells and extensive macrophage infiltration, is a chronic inflammatory disease. Molecular hydrogen, known for its antioxidant properties, has shown promise in eliminating reactive oxygen species. However, the low solubility and bioavailability of hydrogen limit the effectiveness of this therapy. To overcome these issues, we developed a novel yolk-shell heterostructure, H-AAZS (Au/Ag@ZnS modified hyaluronic acid), utilizing a hydrothermal cation exchange process. Through ion doping, semiconductor hybridization, and Schottky barriers in H-AAZS, photocatalysis for hydrogen generation has been successfully implemented using 660 nm laser irradiation. Additionally, the H-AAZS demonstrate the capacity for mild photothermal therapy, inducing apoptosis in synovial cells with Au's hot electrons with 660 nm laser irradiation. This strategy not only improves the abnormal proliferation of synovial cells but also avoids the exacerbation of inflammation caused by thermal stimulation. Both in vitro and in vivo experiments validate the synergistic effects of hydrogen production mediated anti-inflammatory responses, macrophage polarization and photothermal therapy. Therefore, this work represents a significant advancement as it ingeniously harnesses photocatalysis to modulate the synovial microenvironment while mitigating the side effects associated with photothermal therapy. This nanocrystal provides new and valuable insights into the potential treatment of Rheumatoid arthritis.

Alkali and alkaline earth ion exchange affinity in ETS-10 toward aqueous lithium separation

Continuous ion exchange is a more sustainable alternative to current methods for removing common impurities from lithium sources. In this work, we examine ion-adsorbent interactions for Mg2+ and Ca2+ with microporous titanosilicate ETS-10, an ion exchange solid with promising performance, using experimental and computational (density functional theory, DFT) methods. Ion exchange affinity for Mg2+ and Ca2+ using the Na+-form of ETS-10 are quantified from measured equilibrium isotherms, analyzed using a modified Langmuir isotherm accounting for overall stoichiometric desorption/adsorption in the cation exchange process. The equilibrium constant for ion exchange using Na-ETS-10 is greatest for Ca and decreases in order of Mg, K, and Li, respectively. These differences in ion exchange affinity are consistent with trends in DFT-derived ion exchange energies, which account for hydration and solvation of cations using a thermochemical cycle. These equilibrium constant values and ion exchange energies suggest that exchange of Ca2+, Mg2+, and K+ using Na-ETS-10 is more favorable than that of Li+. Indeed, competitive ion exchange of equimolar aqueous mixtures of Li+ and each of K+, Mg2+, or Ca2+ demonstrate selective uptake of the non-lithium cation into the solid, thereby concentrating Li+ in the aqueous solution while removing impurity cations.

Revealing the degradation mechanism of calcium-based air electrodes in reversible solid oxide cells under chromium contaminants

Calcium-based perovskite La0.6Ca0.4Fe0.8Co0.2O3-δ (LCFC) with stable structure is the promising air electrode used in reversible solid oxide cells, and its application in cell stack must consider its Cr poisoning resistance ability. Herein, the Cr poisoning effect of it is studied in this work. The results indicate the strong reaction between LCFC and the Cr contaminations, forming undesirable CaCrO4 impurities, which significantly reduce the activity of ORR/OER. Both the decayed performance and reversible stability are also observed in SOFC and SOEC modes under the Cr contaminations, and the main reason comes from the reduced activity of the oxygen surface exchange processes and the blocked gas diffusion process by the impurities. A worse degenerated performance in SOFC mode than that in SOEC mode is also found in this work. Beyond that, the mechanism of the reaction between chromium contaminants and the Ca-segregation of the electrodes is discussed by the nucleation theory.