Impurity Release Research Articles

Experimental and Numerical Study of Air Flow Reversal Induced by Fire in an Inclined Mine Working

Effective fire prevention in mine workings and tunnels requires a thorough theoretical analysis of the heat and mass transfer processes within these structures. This involves using established models to calculate non-isothermal air flow dynamics in long tunnels and mine workings. While the ventilation of tunnels has been extensively studied, significant challenges persist regarding mine ventilation systems, particularly due to their complex and branched topology. This study aimed to address these challenges and gaps in mine ventilation. We designed a laboratory bench to simulate an inclined mine working with a heat source (fire) and validated a mathematical model of heat and mass transfer in such settings. Using experimental measurements, we verified the model’s accuracy. It is important to note that our experimental and theoretical analyses focused solely on the thermal effects of a fire, without considering the release of harmful impurities. Using the validated model, we conducted multiparameter simulations to identify the conditions leading to the formation of a thermal slug in an inclined mine working and the subsequent reversal of air flow. The simulation data enabled us to determine the dependency of the critical heat release rate on the aerodynamic parameters of the mine working. Additionally, we evaluated the changes in average air density within a mine working at the critical heat release rate. These findings are crucial for the further development of a network-based method to analyze air flow stability in mine ventilation networks during fires.

Divertor enrichment of recycling impurity species (He, N2, Ne, Ar, Kr) in ASDEX Upgrade H-modes

Particle balance calculations are done for the seeding species N2, Ne, Ar, Kr as well as He with the aim of obtaining a realistic description of the divertor and core plasma impurity content. Experimental time traces of main plasma impurity densities are fitted by a single, time-independent parameter v z,ineff . This parameter represents the product of the impurity inward pinch in the pedestal, used for the description of gross fueling here, and the enrichment factor between the sub-divertor gas reservoir and the upstream separatrix. v z,ineff depends strongly on the first ionization energy as well as on the charge Z or mass of the impurity. The prevailing dependence of the enrichment values on the ionization energy suggests the importance of the relative impurity and deuterium ionization lengths in the divertor. Regression analysis of v z,ineff yields an expression for the impurity concentrations in the core and the divertor of ASDEX Upgrade which allows the prediction of the corresponding impurity densities and their divertor enrichment within a factor of 2 with only engineering parameters as input. A simple wall model has been introduced to take into account wall storage and release of impurities, e.g. for conditions of pre-loaded walls due to seeding in previous discharges. Wall effects are observed for all species considered, but wall storage turns out to be more important for N and He compared to Ne, Ar, Kr. Similar enrichment values are obtained for ELMy H-modes and EDA/QCE no-ELM regimes. A factor of approximately 1.4 reduction in enrichment is observed for divertor conditions for pronounced detachment with Ar and N2. The obtained analytical model for the core and sub-divertor impurity densities is well suited for integration into a discharge flight simulator or a real time state observer.

The role of impurities in porous carbons for bioinspired iontronic devices

Ion-controlled electronics use biocompatible electrolytes to realize multiple functions, such as ionic resistors, ionic diodes, and ionic transistors, endowing them with huge biologic application potentials, ranging from sensing to information processing. Biocompatible porous carbons with exceptionally high surface areas enable high capacitance for biologic ions electric-double-layer capacitive devices. However, we find an unexpectedly high content of water-soluble ionic impurities in commercial and custom designed carbons, which affects the capacitive behavior of carbons in the pure water electrolyte and thereby affects the precise control of ions transport induced by electric polarization of porous carbon electrodes. Complementary analytical techniques are used to analyze the commercial clean activated carbon ColorSorb (AC-CS) illuminating the influence of adsorbed ionic impurities for the electrosorption mechanism in a low concentrated bioactive choline chloride (ChCl) electrolyte. Moreover, the comparison of high purity activated carbon (AC-HP) with pure AC-CS suggests the roles of ionic impurities for the capacitive behavior in ChCl and pure water electrolytes. Our work encourages to reconsider the importance of adsorbed ionic impurities for the carbon’s property and application in capacitive devices, and clarifies the influence of ionic impurity release from porous carbon for ion depletion and release processes.

EFFECT OF MODIFYING ADDITIVES ON THE PHASE TRANSITION OF ANATASE TO RUTILE

The results of studies on changes in the chemical composition and structure of doped titanium hydroxide during thermal treatment are analysed. It is shown that anatase is formed at first under heating in all cases, and with further increase in temperature or in the duration of thermal treatment it is transformed into rutile. The temperature of the start of anatase-rutile transition depends on the type of doping component. The transition proceeds not abruptly at a certain temperature but gradually over a wide temperature range, while both compounds can exist simultaneously. At a constant temperature, the proportion of rutile increases with an increase in the duration of thermal treatment. It is concluded on the basis of the conducted studies that the samples of titanium dioxide in the presence of doping components represent the broad classes of non-stoichiometric compounds with different crystal structures, and the transition of anatase to rutile is not a polymorphic transformation of the 1st kind but it is a consequence of various chemical processes involving the release of anionic and/or cationic impurities into the gas or solid phases.

Earthworm granules: A model of non-classical biogenic calcium carbonate phase transformations.

Different non-classical crystallization mechanisms have been invoked to explain structural and compositional properties of biocrystals. The identification of precursor amorphous nanoparticle aggregation as an onset process in the formation of numerous biominerals (crystallization via particle attachment) constituted a most important breakthrough for understanding biologically mediated mineralization. A comprehensive understanding about how the attached amorphous particles transform into more stable, crystalline grains has yet to be elucidated. Here, we document structural, biogeochemical, and crystallographic aspects of the formation as well as the further phase transformations of the amorphous calcium carbonate particles formed by cultured specimens of earthworm Lumbricus terrestris. In-situ observations evidence the formation of proto-vaterite after dehydration of earthworm-produced ACC, which is subsequently followed by proto-vaterite transformation into calcite through nanoparticle attachment within the organic framework. In culture medium spiked with trace amounts of Mn2+, the cauliflower-like proto-vaterite structures become longer-lived than in the absence of Mn2+. We propose that the formation of calcite crystals takes place through a non-classical recrystallization path that involves migration of proto-vaterite nanoparticles to the crystallization site, and then, their transformation into calcite via a dissolution-recrystallization reaction. The latter is complemented by ion-by-ion crystal growth and associated with impurity release. These observations are integrated into a new model of the biocrystallization of earthworm-produced carbonate granules which highlights the sensibility of this process to environmental chemical changes, its potential impact on the bioavailability of contaminants as well as the threat that chemical pollution poses to the normal development of its early stages. STATEMENT OF SIGNIFICANCE: Understanding the mechanisms of nucleation, stabilization and aggregation of amorphous calcium carbonate (ACC) and factors controlling its further transformation into crystalline phases is fundamental for elucidation of biogenic mineralization. Some species of earthworms are natural workbench to understand the biogenic ACC, stabilization and the transformation mechanisms, because they create millimeter-sized calcareous granules from amorphous calcium carbonate, which crystallize to a more stable mineral phase (mostly calcite). This study undergoes into the mechanisms of ACC stabilization by the incorporation of trace elements, as manganese, and the ulterior precipitation of calcareous granules by a coupled process of amorphous particle attachment and ion-by-ion growth. The study points to sensibility of this process to environmental chemical changes.

Corrosion of alloy 690 in simulated steam generator chemistry with boiling-effect of chloride and sulfate impurities

Enrichment of impurities occurs in steam generators of nuclear plants due to intense boiling conditions prevailing within them. In this work, deposition and release of chloride and sulfate impurities were studied using a dedicated water circulation loop with Alloy 690 as steam generator tubing. Electrochemical impedance spectroscopy was employed to follow in-situ the corrosion behavior in non-boiling, boiling and after-boiling conditions. Deposition/release of impurities is quasi-first-order vs. concentration. Interpretation of electrochemical impedance data using an updated version of the Mixed-Conduction Model allows to obtain reaction orders of oxide growth and corrosion release with respect to chloride and sulfate additives.

ВЛИЯНИЕ ЗАГРЯЗНЕНИЯ ОТРАЖАЮЩЕЙ ПОВЕРХНОСТИ НА ПРОЦЕСС СЕПАРАЦИИ РАПСА ПО УПРУГИМ СВОЙСТВАМ

An important stage in the cultivation of rapeseed is its post-harvest processing, which ensures the safety of its sowing, commodity and technological properties. Therefore, the creation of new competitively capable machines that performed this work is an important task. Basically, pneumatic sieve machines are used to clean the grain heap of rapeseed seeds from weed seeds and impurities. However, it is practically impossible to clean rapeseed seeds from bedstraw, neslia paniculata and other weeds whose physico-mechanical properties differ little from the properties of rapeseed seeds without significant losses of the main crop to waste. The most promising and at the same time insufficiently studied method of cleaning rapeseed from difficult-to-separate impurities of weed seeds is separation by springy properties. The article presents the results of production tests of the rapeseed separator by springy properties carried out on the basis of Pichugino LLC in the Vargashinsky district of the Kurgan region. Preliminary tests were carried out with a pile of rapeseed of the «Campino» variety coming from the field from the combine without pre-cleaning, further tests with pre-cleaned rapeseed seeds of the «Campino» and «Lexus» varieties of the 2022 harvest. The analysis of the effect of the yield of the purified fraction of rapeseed seeds, depending on the contamination of the reflective surface, was carried out, as well as the qualitative indicators of the release of grain impurities of weed seeds were determined.

THE INFLUENCE OF TERRAIN, CLIMATIC CONDITIONS AND FACTORS ON THE ATMOSPHERIC AIR MONITORING SYSTEM, BASED ON THE IMPLEMENTATION OF EU LEGISLATION ON THE EXAMPLE OF LVIV REGION

The article is devoted to the influence of terrain, landscapes, and meteorological conditions on the establishment of air quality monitoring points in the relevant territory of the Lviv region. The main factors affecting the distribution of the concentration of pollutants in atmospheric air during the design of air monitoring stations have been determined. It was established that the level of the surface concentration of pollutants increases with an increase in the power of the emission source, the density, and size of impurity particles, and decreases with an increase in the height and radius of the orifice of the emission source, the temperature of the emission, and the rate of release of impurities from the source.

Realization of divertor configuration discharge in J-TEXT tokamak

To extend the operation region of the Joint-Texas Experimental tokamak (J-TEXT) to the divertor configuration and even the H-mode, the divertor configuration discharge has been realized for the first time in the J-TEXT tokamak. Along with the establishment of a power supply for the divertor configuration, the construction of relevant diagnostics, and the installation of the divertor target on the high-field side, divertor discharge has been tested. Through the equilibrium calculation and position stability analysis, the control strategy has evolved to be more stable. High-density experiments and auxiliary heating experiments have been carried out on the divertor configuration. The special midplane single-null (MSN) divertor configuration is shown to be more stable than the limiter configuration in the density limit condition and can reach a higher density in the experiment. In the ECRH experiment, the power injection enhances the electron temperature and density, while more heat outflux is loaded on the divertor target tiles and causes more intensive recycling and impurity release. The future plan for the divertor configuration operation in the J-TEXT tokamak is also included.

Assessment of agricultural waste biochars for remediation of degraded water-soil environment: Dissolved organic carbon release and immobilization of impurities in one- or two-adsorbate systems

This paper presents a method of agricultural waste management — the production of two biochars (BC) from potato and raspberry stems. It defines the potential of these materials for remediation of degraded water and soil environments. The performed study included analyses of BC physicochemistry, dissolved organic carbon (DOC) release and ability to immobilize copper (Cu), tetracycline (TC) and carboxin (CB) in one- and two-adsorbate systems. The BCs were obtained with pyrolysis at 600 °C for 30 min in a nitrogen atmosphere. Their DOC was predominantly constituted of substances with large molecular weights and high aromaticity, meaning that both BCs can be safely applied as soil additives. Potato-biochar (P-BC) had a more developed surface than raspberry-biochar (R-BC). The specific surface area (SBET) of P-BC was 122 m2/g, whilst of R-BC was 87 m2/g. As a result, the efficiency of impurity adsorption in the one-adsorbate systems was higher for P-BC (61.75% for Cu, 73.84% for TC, and 54.43% for CB). In the two-adsorbate systems, organic impurities improved the immobilization of heavy metal ions on BCs. The efficiency of Cu adsorption on P-BC when TC was present was 88.29%. Desorption of Cu from BC was highest using HCl, whilst that of TC and CB was highest using NaOH. Maximum desorption was observed in a two-adsorbate system with TC + CB (up to 63.6% for TC). These results confirmed that potato and raspberry stems can be used to produce highly effective BCs with large application potential, especially for remediation of degraded soils and polluted waters.

Fluidized bed centrifugation of precipitated and flocculated cell cultures: An intensified clarification approach for monoclonal antibodies

Precipitation and flocculation pretreatments promise improved clarification of cell culture fluids (CCF) to intensify the production of monoclonal antibodies (mAb). However, such pretreatments pose the risks to alter the mAb and damage cells. This can be additionally exacerbated by the subsequent clarification process, for example by high shear forces during disk stack centrifugation, resulting in a release of host cell impurities. To overcome these limitations and enhance the clarification particularly of cell cultures with low viability and thus a high level of impurities, this study investigated low-pH precipitation and cationic polymer flocculation, each in combination with a mild fluidized bed centrifuge (FBC) separation and a subsequent filtration step. Therefore, low-viable CCF´s were pretreated and characterized to investigate the effects of additives on CCF composition and stability. In clarification experiments, both pretreatments achieved similar FBC throughput compared to an untreated reference but increased the maximum filter throughput up to four times. Furthermore, high mAb recoveries (> 91%), low turbidities (< 3.1 NTU) and high DNA removals (> 91%) were achieved. Similar glycan profiles and dimer ratios suggest consistent mAb quality. These findings have a great potential to intensify mAb downstream processing with both CCF pretreatments using a FBC clarification approach.

An Eco-Friendly Phosphogypsum-Based Cementitious Material: Performance Optimization and Enhancing Mechanisms

Little published data were effective in decreasing the setting time and improving the strength development of phosphogypsum-based supersulfate cement (P-SSC) containing an excess of 40% phosphogypsum to achieve adequate field working and mechanical properties. This study aimed to optimize the application performance of P-SSC by wet grinding, the enhancement mechanism of which was discussed further. The wet grinding mainly refined and dispersed the phosphogypsum with the large particle size, improving the formation of ettringite by increasing the supersaturation of phosphogypsum. However, the release of impurities prolonged the setting time of P-SSC pastes, leading to a lower early strength. Short-time wet grinding destroyed the surface structure of slag with the small particle size, presenting a higher hydration degree. It seemed to have a more significant improvement of generated C-(A)-S-H gel, while treating P-SSC by wet grinding slightly enhanced strength development. Increasing the aluminate concentration by incorporating active aluminum phases in this process significantly promoted the generation rate of ettringite and weakened the negative effect of impurity release. Therefore, a feasible and effective method to prepare P-SSC pastes was proposed to realize the large-scale application of phosphogypsum in the building materials industry.

СПОСОБ ОПРЕДЕЛЕНИЯ ОПТИМАЛЬНОЙ ДЛИНЫ ТРИЕРНОГО ЦИЛИНДРА

. It is known that agricultural enterprises are equipped with grain cleaning units of the ZAV40 and KZS-40 types. It is known that in 90% of cases trier blocks of units are taken out of service, since they do not provide the required quality of grain cleaning and are unreliable in operation - technological failures occur due to blockages of cellular cylinders. This problem can be partially solved by using indented blocks with the optimal length of the indented cylinder. This will lead to a significant reduction in the loss of clean grain to waste while maintaining an acceptable level of residual contamination and increasing reliability. A mathematical model has been developed for the operation of the grading unit according to the parameters of residual contamination and losses of clean grain. It was found that the residual contamination decreases exponentially along the length of the doll cylinder. The loss of clean grain to waste grows linearly. It was found that the loss of pure grain to waste along the length of the oat cylinder decreases exponentially. A formula has been obtained to determine the optimal length of the indented cylinder, which depends on the degree of impurity release and the amount of pure grain loss for the doll cylinder. The criterion of optimal operation of the indenter block has been substantiated. The hypothesis about the same degree of impurity release along the entire length of the indented cylinder was confirmed. On the basis of the results obtained, recommendations are given for the developers of indented blocks.

Glass: The best material for pharmaceutical packaging

AbstractGlass is the most used material in pharmaceutical packaging, and the production volumes are continuously growing. The reasons why glass can be considered the best material for pharmaceutical containers are discussed. A current picture of this area, which was showcased during the Covid‐19 pandemic, is provided. Borosilicate glass products, which are currently the most used among those described by the Pharmacopoeia, are mostly considered, but new glasses that may be introduced in the future are also mentioned. A short view on the evolution of this type of glass and the current market situation are provided. Particular emphasis is given to chemical durability. Glasses are generally considered inert from the chemical point of view, but this is not exactly true. Phenomena such as the release of elemental impurities into solution, buffer interaction, and delamination have caused much concern in the last decade or so, especially as the complexity and value of drugs has been increasing. These phenomena are described, and it is pointed out that, thanks to the increasing scientific knowledge and production technologies, these issues are now under control, and the products on the market are of very high quality and very reliable.

Development of the pneumatic system with an annular aspiration channel for vibrating and rotation grain separator

The pneumatic system with a vertical annular aspiration channel for vibration-centered grain separators been developed. The rational values of the disk grain distributor are the length of the sectors 0.15 m, the angle of inclination of the sectors 60°. The rotation speed of the distributor in the seed mode (grain supply 5…15 t/h) should be 100…200 min-1 and in the food mode (grain supply 15…25 t/h) must be 100…150 min-1. The effect of the release of light impurities in the developed aspiration system decreases from 45% to 20% with an increase in the supply of grain G from 5 to 25 t/h, herewith at the same time the loss of a full-fledged grain to waste decreases from 0.6...0.8% to 0.3...0.4%, while the effect of the release of light impurities in the aspiration system of the mass-produced vibration centrifugal grain separator decreases from 11% to 4% with the same losses of grain to waste.

Detergency mechanisms and cellulosic surfaces: A review

The release of soils and impurities from cellulosic surfaces plays a critical role in such processes as the laundering of clothes and the deinking of wastepaper pulps. This article reviews publications that provide evidence about factors that affect such release and the mechanisms by which such factors operate. In general, cellulosic substrates provide advantages for the release of contaminants due to their hydrophilic nature and due to their permeability, allowing the transport of surfactants to contact interfaces with dirt. However, the same permeability of cellulosic material also provides opportunities for contaminants to work themselves into internal crevices and pores, from which they are difficult to remove. The article also reviews aspects of theory related to detergency and how those theories relate to the laundering, deinking, and purifying of substrates based on cellulose and related plant materials. Cellulose and some of its derivatives also can play a role in detergent formulation, especially as builders or as finishes placed on textile surfaces, which sometimes aid in the release of dirt.

Estimation of impurity release from planar liquid surface in plasma

A liquid metallic surface exposed to a plasma interacts with ions and electrons numerously. The surface becomes charged. Subsequently, the electric field is formed via the balance of incoming ion and electron currents. The kinetic energies and the momentum of the incoming ions and electrons are transferred to the surface. This is enhanced by the self-generated electric field and gives rise to notable pressures and energy fluxes on the surface. By adopting several plasma and liquid parameters to the physical models, the time evolution of the surface temperature can be characterized with the net energy flux, the net pressure, and the net impurity outgoing flux. The study suggests that electron temperature and ion mass significantly govern, but the ion to electron temperature ratio does not, the trend of the surface temperature. Besides, it is found that at long elapsed time at which evaporation becomes strong, the energy and impurity fluxes reduce in conjunction with the rate of change of the surface temperature lessens.

Shelf life of plasma focus chambers with deuterium-tritium filling

The paper presents the results of an experimental study of the shelf life of sealed plasma focus chambers with deuterium-tritium and deuterium fillings. Shelf life is defined as maintaining the level of neutron yield during operation of PF chambers as part of pulsed neutron generators after long storage intervals. The release of impurities from the inner surfaces of the PF chamber and the accumulation of he-lium He3 due to the decay of tritium in the volume of the sealed-off PF chambers leads to a significant decrease in the neutron radiation yield several years after the chamber is filled with the working mixture. The paper shows that the shelf life of the chambers is significantly increased when using a gas generator, in which hy-drogen isotopes are contained in a bound state, and are released into the inner volume of the chamber only for the duration of operation as part of neutron gen-erators. It has been shown experimentally that spherical chambers of the PF9 type provide a level of neutron radiation yield Y, close to the initial value in the manu-facture of chambers, after more than 10 years of storage.

FORMULATION AND EVALUATION OF FIXED-DOSE COMBINATION OF BILAYER TABLETS OF ATAZANAVIR SULFATE AND RITONAVIR 300 MG/100 MG

Objective: The objective of this study is to formulation and development of fixed-dose combination as a single dosage regimen by using the design of experiments (DOE) approach against the single dose of reference listed drugs of brand reyataz capsule 300 mg (atazanavir sulfate) and norvir tablets 100 mg (ritonavir tablets) to treat human immunodeficiency virus (HIV) Infections. Methods: Formulation was developed with each blend of ritonavir by using hot-melt extrusion and atazanavir sulfate by wet granulation process and compressed by bilayer technology followed by film coating. Formulation and process optimization by design of experiments (DOE) to evaluate dissolution and related substances of the finished product. Fractional factorial (22+3) and full factorial design (33+3) by using a design expert (version 11.0) were used to evaluate the formulation and process variables to prepare a robust formulation. Results: Results indicate that the sorbitan monolaurate range has played a key role to achieve the dissolution for ritonavir formulation. The studied temperature range and interaction of temperature and feed rate, temperature and screw speed during the hot-melt extrusion process impact on the related substances of the bi-layer tablet. Analysis of variance (ANOVA) also finding the P-value less than 0.0500 and the studied range was significant. Design space was established for the significant factors to control the results within the acceptable limits. The studied formulation and wet granulation process for atazanavir sulfate have no significant impact on dissolution and related substances of the finished product. Further, the studied hardness range of 16-28kp for bi-layer tablets has no critical impact on the dissolution. Optimum formulation and process of bi-layer tablets in F37 yielded similar drug release and related substances against the reference drug product. Conclusion: The present invention of fixed-dose combination can be recommended as a single dosage regimen with the consistent drug release and control of the unknown impurities in the prototype formulation against the individual reference drug product.

Effects of carbon impurity on tritium diffusion and helium formation in γ-LiAlO2 pellets: A first-principles study

Gamma-phase lithium aluminate (γ-LiAlO2) in the form of annular pellets is used as a breeding material in tritium-producing burnable absorber rods (TPBARs) for the production of tritium by thermal neutron irradiation of 6Li. Significant radiation damage occurs in γ-LiAlO2 due to neutrons, and tritium and helium (He) nuclei, which recoil through the crystal. The radiation-damaged crystal is rich with vacancies and impurities such as carbon (C) that can act as tritium trapping sites. The presence of C impurities can hinder 3H diffusivities significantly. Here, we studied the effect of C impurities on 3H diffusivity and energy barriers in γ-LiAlO2 using first-principles density functional theory. In addition, we studied the He diffusion in an undefective γ-LiAlO2. We calculated the energy barrier for diffusion in γ-LiAlO2 to be 0.98 eV for substitutional 3H in the presence of a C impurity. At 600 K, the corresponding diffusion coefficient was calculated to be 7.98×10-14m2/s. Similarly, we calculated the energy barrier for He diffusion to be 0.12 eV, which was along the crystallographic c-direction. The corresponding diffusion coefficient for He at 600 K was calculated to be 6.8×10-7m2/s. This work may open further theoretical and experimental avenues on impurity effects and release of He from γ-LiAlO2.