Fine Filter Research Articles

МЕМБРАННАЯ ОЧИСТКА ОБВОДНЕННОГО ТОПЛИВА

A promising way to solve the problem of waterlogging of motor fuel may be the use of modern filter materials. Membrane filters are widely used in various technological processes. They are capable of working for a long time, are quite durable and chemically resistant. The possibility of using membrane materials in the purification of artificially watered diesel fuel has been investigated. For the analysis of membranes, an installation has been designed that allows fuel to be pumped through the test material at different pressures. The pressure is created without using a pump, but due to compressed air from the compressor unit. As a filter material, Vladipor flat synthetic membranes of the MFFK-3, MFFK3G brands and watered diesel fuel with a water content of 0.5%, 1%, 3% and 5% were used (the volume of the initial fuel sample was 1 liter). The water content in the initial diesel fuel was calculated according to the Dean-Stark method. It was found that with increasing pressure, the degree of purification of the watered fuel by the hydrophobic membrane MFFK-3 increases (improves by 45-70%), in the case of the hydrophilic membrane MFFK-3G decreases (10-14%). The hydrophobic membrane with minimal water content (0.5%) allowed to reduce the water content in the initial fuel sample from 5 ml to 0.25 ml (by 95%), hydrophilic from 5 ml to 4.25 ml (by 15%). The water residue in the permeate after the hydrophilic membrane is significantly higher. The studied membranes of the MFFK-3 and MFFK-3G brands are capable of purifying diesel fuel from water when used as a fine filter.

Performance evaluation and factors influencing a drinking water treatment plant, Shire Indassilassie, Ethiopia

This research assesses the efficacy of the water treatment plant in Shire Indassilassie, Tigray, Ethiopia, focusing on the slow sand filtration system. Despite the inclusion of horizontal roughing filtration and a sedimentation tank, the water treatment plant struggles with an inadequate and turbid water supply. This study evaluates the water treatment plant’s performance through field evaluation, interviews, and laboratory experiments, concentrating on major treatment processes to identify performance-limiting factors. The water source had an average turbidity of 29.70 ± 1.03 NTU in the dry season and 94.27 ± 16.71 NTU in the summer. Results indicate that horizontal roughing filtration, sedimentation tank, and slow sand filtration achieve average turbidity removal efficiencies of 42.02% ± 4.00%, 5.67% ± 3.15%, and 83.51% ± 8.75%, respectively, during the dry season. In the summer or wet season, these treatment units achieve efficiencies of 40.06% ± 3.26%, 28.17% ± 4.62%, and 77.07% ± 4.61%, respectively. Additionally, the average run times for slow sand filtration are 22 days in the dry season and 13 days in the summer. Total and fecal coliform removals were effective, except in the sedimentation tank. A one-way ANOVA confirms a significant difference in turbidity among treatment units. Factors such as fine filter sand particles causing faster clogging, pipe misconnections, inadequate cleaning practices, irregular filtration rates, air binding due to a lack of backfilling at startup, and a lack of periodic monitoring and emergency response lead to suboptimal turbidity removal and shorter slow sand filtration run times. The study underscores the need for corrective measures to address these issues, enhancing water treatment plant sustainability in the region.

Justification of the Locations of Differential Pressure Sensors for Coarse and Fine Filter Elements Installed one Inside the Other in a Single Gas Filter Housing

Statement of the problem. The relevant task of ensuring the uninterrupted operation of modern gas pressure reduction systems is to develop and comprehensively substantiate the possibility of using two-stage filters for natural gas purification in gas reduction points and theoretically substantiate the method for calculating the pressure drop in cylindrical filter elements (CFE). Results. It is proved that when gas flows in the upper cross section of the filter, the pressure drop will be less than in lower cross sections, including the pressure drop in the lowest cross section. This leads to a larger amount of leaking gas, to a larger mass of impurities settling in the lower part of the filter elements of cylindrical coarse and fine cleaning and to a greater degree of their clogging. Therefore, it is recommended to place gas pressure sensors in the lower part of the internal volume of the coarse and fine-cleaned CFE, so that the flow direction of the coarse and finely purified gas washing the sensors at the location of the hole for measuring statistical pressure is tangential to the side surface of the sensor tube. Then the flow direction of the roughly and finely purified gas entering the holes of the sensors is carried out at an angle of 90° and the pressure gauges measure the static pressure. Conclusions. The locations of pressure drop sensors on coarse and fine filter elements installed one inside the other in a single gas filter housing are substantiated. The proposed arrangement of differential pressure sensors will significantly increase the possibility of receiving an earlier signal about the degree of clogging of the gas filter at the control room, as well as have a significant amount of time for timely removal of blockages formed in the coarse cleaning CFE and replacement of fine cleaning CFE.

Fine material filtration using conventional pressure and steam pressure: a relationship between filter cake height to crack formation and residual moisture content

Crack formation is an undesired phenomenon encountered frequently during the filtration process, especially in fine particulate filter cakes. This phenomenon causes disadvantages related to the dewatering efficiency and washing efficiency. The filter cake height has not only an effect on crack formation but also meaning in the economic and operational of filtration. In this research, Limestone and Coal are the chosen fine powder materials to survey the effect of this factor during conventional pressure filtration (CPF) and steam pressure filtration (SPF). The permeability ratio is suggested to quantify cracking while the saturation and the residual moisture content indicate the water remaining. Test results show lower dewatering efficiency as well as an increasing trend of probability and degree of cracks when the filter cake becomes thicker. By visual observation, macro- and micro-cracking are described for shrinkage behavior on filter cake. The delamination was also mentioned and observed after filtration. Steam pressure filtration (SPF) is introduced as one of the methods to reduce the degree, even prevent the formation of cracks as well as improve the dewatering efficiency.

Experimental study on enhancing electrostatic charging of nonwoven filter media through novel electrode configurations

The COVID-19 pandemic has underscored the urgent need for efficient particle filtration to tackle public health challenges. This study compares the electrostatic charging capabilities of two types of electrodes: conventional Metal Lamellar Electrodes (MLE) and Modified Lamellar Plate Electrodes (MLPE) with PMMA insulation, in their role of charging nonwoven polypropylene filter media. Experimental analysis unequivocally demonstrates the superiority of MLPE in promoting effective electrostatic charge, as influenced by applied high voltage and inter-electrode distance, resulting in a significant enhancement in fine particle filtration. Numerical simulations of the electric field conducted using the COMSOL software and employing the Finite Element Method (FEM) validate these findings. FEM discretizes the domain into small finite elements and applies Laplace's equation in charge-free regions, providing a comprehensive understanding of the behavior of dual-electrode corona discharge systems. These simulations indicate higher field intensities for MLPE compared to MLE.By integrating experimental and numerical analyses, this study sheds light on the potential benefits of MLPE for air filtration systems, offering a noteworthy advancement in the control of airborne infections and reduction of environmental health risks. This research lays the groundwork for the development of more efficient and durable filtration systems, meeting the increasing demands for public health protection.The findings of this study suggest that the adoption of MLPE could significantly contribute to improving indoor air quality and mitigating the transmission of respiratory diseases. MLPE may also find utility in industrial filtration and air purification in sensitive work environments. Ultimately, this research sets the stage for the development of more efficient and sustainable filtration systems, addressing the growing needs for public health protection.

Influence of selected contaminations and melt filtration on the properties of ABS and ABS recyclate

AbstractPlastic recyclates can be contaminated with a variety of impurities due to their previous life, which cannot always be perfectly separated in recycling pretreatment steps. Hence melt filtration is an important step in reprocessing plastic recyclates to achieve material of sufficient purity, but it also leads to more stress on the material due to higher pressures and longer processing times. In our study, we investigated the influence of typical particulate impurities as may occur in recyclate on the mechanical and rheological properties of ABS. Even low amounts of contaminations lowered the key properties. Melt filtration of post‐consumer ABS recyclate with different mesh size melt screens showed little improvement of mechanical properties, but longer idle times and loss of material. Damage to the material caused by finer filtration could be shown by thermal measurements.Highlights Determination of properties of ABS contaminated with 0.5–2.0 wt.% of selected impurities (wood and rubber particles). Melt filtration of post‐consumer ABS recyclate with different melt screens. Investigation of process and properties of filtered ABS recyclate.

ASSESSMENT OF THE SAFETY AND QUALITY OF RAW MILK FOR THE IMPROVEMENT OF TECHNOLOGICAL PROCESSES OF PRIMARY MILK PROCESSING

As you know, the quality of milk cannot be improved during its processing, therefore the milk quality management system at production facilities should be focused on high-tech processes of its production. It has been scientifically proven that the process of obtaining and collecting milk, its primary processing, storage and transportation are the least controlled production processes. Therefore, the study of the milking technology impact and primary processing on the quality of the obtained milk remains relevant. An analysis of production and primary processing of milk was carried out at the farm of “Lany Vinkovechchyny” LLC in Khmelnytskyi region, and in order to improve the quality of the obtained milk raw materials, it was proposed to optimize the technology of primary processing of milk, in particular, to supplement the traditional scheme of primary purification with a fine filter. It was established that there is a dependence between the quality of raw milk and the technology of primary processing, so with successive purification of milk with a filter of coarse and then fine purification, the number of mesophilic aerobic and facultatively anaerobic microorganisms (KMAFAnM) in milk was at the level of 228 thousand CFU /cm3, which corresponds to the highest grade, at the same time, during one-time filtration in a closed flow with a coarse filter, the milk contained 332 thousand CFU /cm3, which is according to DSTU 3662:2018. corresponds only to the first kind indicator. After double filtration, only 259,000/cm3 somatic cells were found in the milk samples, which is 27.6% less than in the milk samples that underwent single purification. The proposed measures to improve the quality and safety of raw milk through the consistent use of filters for coarse and fine primary cleaning made it possible to increase the quality of milk and increase financial income for the farm.

Potential deformation assessment of Semantok Main Dam in North Nganjuk Region at East Java Indonesia

Semantok Dam was constructed using a zone l embankment type and required safety measures for deformation control. This study aims to understand material specifications, geological conditions, and deformation behavior. The results of the material specifications indicate that the core material and fine filter material meet the design criteria. The geological conditions comprise sand, sandstone, and claystone. The rock’s bearing capacity and settlement in the core zone are considered safe. The elastic vertical deformation of the foundation, analyzed using a flexible foundation approach by Lord, is estimated to be between 4.36 and 6.10 cm. Dynamic analysis is also performed using the Plaxis 8.6 version software to estimate deformation. The software input includes soil properties from the borrow and quarry areas surrounding the dam site. Earthquake design criteria are based on the Operating Basis Earthquake (OBE) with a 100-year return period and the Maximum Design Earthquake (MDE) with a 10,000-year return period. The dynamic analysis results indicate that the maximum deformation during a 100-year return period earthquake is 7.37 cm (horizontal deformation) and 12.68 cm (vertical deformation). In the case of a 10,000-year return period earthquake, the maximum deformation is 83.41 cm (horizontal deformation) and 175 cm (vertical deformation) during rapid drawdown.

High-resolution Si3N4 spectrometer: architecture & virtual channel synthesis and experimental demonstration.

Up-to-date network telemetry is the key enabler for resource optimization by capacity scaling, fault recovery, and network reconfiguration among other means. Reliable optical performance monitoring in general and, specifically, the monitoring of the spectral profile of WDM signals in fixed- and flex- grid architectures across the entire C-band, remains challenging. This article describes a two-stage spectrometer architecture amenable to integration on a single chip that can measure quantitatively the spectrum across the entire C-band with a resolution of ∼ 1.4 GHz. The first stage consists of a ring resonator with intra-ring phase shifter to provide a tuneable fine filter. The second stage makes use of an AWG subsystem and a novel processing algorithm to synthesize a tuneable coarse filter with a flat passband which isolates individual resonances of a multiplicity of ring resonances. The spectrometer is capable of scanning the entire C-band with high resolution using only one dynamic control. Due to its maturity and low loss, CMOS compatible Si3N4 is chosen for fabrication of the ring resonator and two cyclic AWGs. Complete spectrometer operation is demonstrated experimentally over a selected portion of the C-band. A novel virtual channel synthesis algorithm based on the weighted summation of the AWG output port powers relaxes the conventional AWG design requirement of a flat passband and sharp transition to stopband. The operation of the circuit is invariant to the optical path length between individual components and the algorithm corrects to some extent fabrication process variation impairments of the AWG channel spectra substantially improving robustness.

On the Influence of Fine Particle Migration and Deposition on Gas Hydrate Production: Insights from the First Trial Production in the South China Sea

Summary As a promising alternative energy source with vast reserves, the primary challenge in exploiting natural gas hydrates (NGHs) lies in achieving long-term safety and efficiency. Several production tests conducted globally have demonstrated that the production of solid particles is one of the main factors contributing to this issue. However, most studies on assessing NGH production capacity have overlooked this phenomenon and its impact on production performance, potentially compromising the accuracy of simulation results. Therefore, this study aims to quantitatively analyze the impact of fine particle migration and deposition on gas production by numerically examining the first NGH production test conducted in the Shenhu area of the South China Sea (SCS). Through comparison of simulation results with the reconstructed gas production curve, the model was calibrated and enabled an explanation of unique gas production performance during field testing. It is found that the deposition of solid particles reduced the gas production rate by nearly an order of magnitude during the initial stage of exploitation. Long-term simulation results indicate that only the three-phase layer (TPL) remains partially unobstructed and serves as the primary source of gas production in later stages. Sensitivity analysis reveals that both depressurization and particle control strategies exert significant effects on particle migration, which in turn affects gas production. Specifically, the increase in depressurization amplitude does not necessarily lead to improved gas production behavior beyond a certain threshold (approximately 6 MPa). This study illustrates the inherent trade-off between preventing particle production and increasing gas production, highlighting the need for a safe and efficient production scheme that strikes a balance between these two objectives. Based on the current study, it is preliminarily recommended to maintain a depressurization amplitude of approximately 6 MPa with a maximum depressurization rate of 3 MPa/d and ensure a fine particle filtration ratio of no less than 95%.

Lipid composition and physicochemical parameters of unrefined sunflower oil

Unrefined sunflower oil is obtained by pressing of the sunflower seeds and subsequent fine filtration. It contains more biologically active substances compared to the refined one, it is more stable to oxidation processes, for that reason it is widely used in the composition of the various food products. The main acids in the oil are oleic (56.5%), linoleic (31.7%), palmitic (6.4%), and stearic acid (3.2%). Total sterol content is 0.7%, with ß-sitosterol as a main component (84.0%). The quantity of tocopherol is 188 mg/kg and it consists of one compound α-tocopherol (100%). Different physicochemical parameters were obtained at temperature ranges (from 20 to 80°C). The values of these parameters decrease with an increase in temperature, density (from 0.938 to 0.901 g/ml), surface tension (from 44.124 to 31.787 mN/m), dynamic viscosity (from 29.195 to 14.913 mPa.s), and kinematic viscosity (from 31.125 to 16.552 mm2/s). All these changes are in confirmation of the data from the literature and are relevant in our next studies.

Inter-annual changes of zooplankton in the kultuk zone of the Volga River delta in the spring period

The studies conducted in spring have shown the main trends in changes in the structure of zooplankton in the kultuk zone of the Volga River delta in years that differ in hydrological and temperature regimes. It was revealed that in low-water years (2012, 2014), with a decrease in the volume of runoff, water level, and a reduction in the duration of floods, zooplankton was characterized by relatively low species richness, high biomass of Copepoda and Cladocera. At the same time, the highest rates of specific species richness, biomass and abundance of all zooplankton groups were observed at spring of a low-water year (2014), which was characterized by a runoff volume during the flood of 101 km3, a high pre-flood water levels, the absence of a sharp and significant dilution, as well as an early warm spring and gradual warming of the waters. In the year (2012), characterized by a volume of runoff during the flood period of 114 km3, a decrease in water level and a sharp increase in temperature before the flood, and then its rapid rise with dilution by cold waters, zooplankton was distinguished by the minimum species richness, a low number of ecological groups and low abundance of Cladocera, but a high proportion of juvenile copepods (fine filter feeders) and in terms of biomass of active euryphagous predators and euryphagous collectors. In a medium-water year (2013) with a large volume of runoff during the flood of 140 km3, with early and high and long floods, zooplankton was distinguished by a high total number of species encountered, but a minimum abundance and biomass, which is associated with the “dilution effect” and an increase in the areas of flooded rich in higher aquatic vegetation.

A new aerodynamic endonasal filtration technology for protection against pollutants and respiratory infectious agents: evaluation of the particle filtration efficacy.

An innovative nasal filter was tested, based on aerodynamic air filtration and not on conventional air filtration by means of mesh filters. A custom testing system was designed and three sizes of the filter have been tested vs. monodispersed SiO2 particles sized 5 μm, 1 μm, and 0.5 μm under cycling flow of 6 liters per minute, provided by an artificial lung breather simulating spontaneous breathing. Accelerated testing was implemented, challenging filters with a maximum load of 200 mg per cubic meter. All three filters' sizes showed initial filtration efficiencies above 90% vs. all particles' sizes, decreased to not less than 80% after 30 min of accelerated testing, corresponding to 4.5 days of continuous use at 2 mg challenge, this value being associated with hazardous air conditions in the PSI scale. Results in this study indicate that nasal filters based on aerodynamic air filtration can provide fine and ultrafine filtration, offering protection in day-to-day life from risks associated with pollens, mites, PM, pollutants, and respiratory infectious agents, introducing acceptable respiratory resistance.

Characterizing moisture occurrence state in coal gasification fine slag filter cake using low field nuclear magnetic resonance technology

ABSTRACT Gasification fine slag, a carbon-rich solid waste produced during coal gasification, is currently disposed of through conventional landfilling methods. Its high-water content hampers resource utilization by reducing its calorific value. This study employs low field nuclear magnetic resonance (LF-NMR) analysis to investigate the water occurrence states in a filter cake with 70.7% moisture content derived from fine gasification slag of the Ningxia coal water slurry furnace. The analysis reveals that free water constitutes a major proportion (68.28%), while combined and capillary water accounts for 2.62% and 2.33%, respectively. The removal of moisture from the coal gasification fine slag filter cake is significantly affected by the drying temperature. The drying rate initially increases and then decreases with different temperatures. For drying temperatures of 60, 70, 80, 90, and 100°C, the maximum drying rates are achieved at 1.09, 1.23, 2.18, 3.86, and 4.01%/min, respectively, with corresponding durations of 40, 40, 25, 30, and 35 min. The T22 relaxation peak area continually decreases and shifts leftward on the coordinate axis. The behavior of the T23 and T22 peaks follows a similar pattern, indicating that water with higher mobility is easily eliminated during drying, while the T21 peak exhibits a robust signal strength throughout the drying process. At a drying temperature of 100°C, the proportion of free water (A22) decreases from 87.3% to 0, the A23 fluctuates between 0 and 5.3%, and the bound water peak area (A21) increases from 10.4% to 94.7% as drying time prolongs. A relationship model is developed between the moisture content of the coal gasification fine slag filter cake and the total integral area of the LF-NMR test, enabling rapid detection and analysis of the total moisture content and distinct occurrence states in the filter cake.

Numerical simulation of a multilayer granular bed filter: Effect of bed structure on the filtration characteristics of high-temperature particulate matter

Fine particulate matter limits the widespread use of granular bed filter due to the difficulty of being trapped by a granular bed. In this paper, a coupled EDEM–Fluent simulation was used to describe the contact adhesion between fine particles and filter granules using the Johnson–Kendall–Roberts model. The effects of inlet gas temperature, inlet gas velocity, and filter layer arrangement on dust removal efficiency were investigated. Results show that the dust removal efficiency decreases continuously with increasing inlet temperature when thermophoresis is ignored, and dust removal efficiency decreases and then increases when thermophoresis is added, with the turning point at 973 K. The effect of inlet gas velocity on dust removal efficiency is relatively small. By optimizing the granular bed structure using a 4:1 granular size ratio arrangement, dust removal efficiency is increased by >20% compared with a 2:1 structure, whereas pressure drop only increases by 248.15 Pa.

Comparison of host cell protein removal by depth filters with diatomaceous earth and synthetic silica filter aids using model proteins.

A number of studies have demonstrated that depth filtration can provide significant adsorptive removal of host cell proteins (HCP), but there is still considerable uncertainty regarding the underlying factors controlling HCP binding. This study compared the binding characteristics of two fine grade depth filters, the X0SP (polyacrylic fiber with a synthetic silica filter aid) and X0HC (cellulose fibers with diatomaceous earth (DE) as a filter aid), using a series of model proteins with well-defined physical characteristics. Protein binding to the X0SP filter was dominated by electrostatic interactions with greatest capacity for positively-charged proteins. In contrast, the X0HC filter showed greater binding of more hydrophobic proteins although electrostatic interactions also played a role. In addition, ovotransferrin showed unusually high binding capacity to the X0HC, likely due to interactions with metals in the DE. Scanning Electron Microscopy with Energy Dispersive Spectroscopy was used to obtain additional understanding of the binding behavior. These results provide important insights into the physical phenomena governing HCP binding to both fully synthetic and natural (cellulose + DE) depth filters.

Sand filtration for greywater treatment: long-term performance evaluation and optimization by response surface methodology

ABSTRACT Greywater treatment and reuse is getting increasing attention all over the world, and sand filters are one of the on-site greywater treatment alternatives. Effects of media size, media depth and flow rates on the performance of the continuously operated saturated sand filters treating greywater were evaluated in this study. River sand of three different media sizes 0.30-0.60 (fine), 0.60-0.85 (medium), and 0.85-1.18 (coarse) mm was used and sand filters with the same media size were constructed and operated at flow rates of 10 (320 L/m2/day), 20 and 30 L/d. Fine sand media filter operated at a hydraulic loading rate of 320 L/m2/day gave the best performance with 99, 94 and 95% removal of turbidity, BOD and COD, respectively. NH4-N, PO4-P and FC were reduced by 84, 99% and 1.65 log, respectively. An optimization study showed an optimum sand size of 0.68 mm and a hydraulic loading rate of 470 L/m2/day.

ОСОБЛИВОСТІ ЗАСТОСУВАННЯ РЕАКТИВНИХ ПАЛИВ ДЛЯ АВІАЦІЙНИХ ГАЗОТУРБІННИХ ДВИГУНІВ

The purpose of this article is to study the features of the usage of jet fuels for aviation gas turbine engines and the importance of the chymotology for the study of aviation kerosene and technical fluids usage in the of modern aviation technology. The role of practical aviation chymotology in ensuring reliable operation of aviation equipment and functional application of fuel and lubricants and technical fluids in existing and future aviation equipment is revealed in the work. In the present time jet fuels of both domestic and foreign production are supplied to meet the needs of the Air Force. The main tasks of chemical engineering are: the study of the processes that take place in the use of fuel on modern aircraft and the justification of requirements for the level of quality of aviation jet fuels and the assessment of the possibilities of its use, the development of the approaches of the optimization of the fuel quality, unification and standardization of quality assessment methods. Modern aviation jet fuels are produced from oil in the process of direct distillation on atmospheric tubule or on an atmospheric vacuum tubule and purification of the kerosene fraction with the addition of the necessary additives in order to improve performance. Thermal stability is important for jet fuels, especially for supersonic aviation fuels, since in modern aircraft with supersonic flight speed airfield heating of aircraft structures to high temperatures takes place due to adiabatic air compression in front of the aircraft. The surface temperature of the aircraft at a speed of 3 Mach can reach +330oC , and at 4 Mach can reach + 630oC. The main direction of improving the thermal stability of jet fuels, especially for supersonic aviation, is to improve the design of aircrafts and aircraft engines, as well as to improve the quality of jet fuels. The main ways of increasing of the thermal stability of jet fuels are changes in the technology of fuel production, an improvement of cleaning technologies, the use of more efficient additives, the use of fine filtration of nitriding of fuels and fuel pre-cooling. Keywords: fuel and lubricants, technical fluids, practical aviation chemistry, quality control, operational properties, gas turbine engine, efficiency and reliability of operation, physicochemical properties.

Characteristics and Oxidative Potential of Ambient PM2.5 in the Yangtze River Delta Region: Pollution Level and Source Apportionment

Fine particulate matter (PM2.5) is a major contributor to the degree of air pollution, and it is associated with a range of adverse health impacts. Moreover, the oxidative potential (OP, as a tracer of oxidative stress) of PM2.5 has been thought to be a possible determinant of its health impact. In this study, the OP of 136 fine aerosol filter samples collected in Changzhou in two seasons (spring and summer) were determined using a dithiothreitol (DTT) assay. Source apportionments of the PM2.5 and DTT activity were further performed. Our results showed that the daily average ± standard deviation of the DTTv (volume-normalized DTT activity) in the PM2.5 was 1.16 ± 0.58 nmol/min/m3 and 0.85 ± 0.16 nmol/min/m3 in the spring and summer, respectively, and the DTTm (mass-normalized DTT activity) was 13.56 ± 5.45 pmol/min/μg and 19.97 ± 6.54 pmol/min/μg in the spring and summer, respectively. The DTTv was higher in the spring compared to the summer while the opposite was true for the DTTm. Most of the detected components (including the organic component, element component, NH4+, Mn, Cu, Zn, etc.) exhibited a moderately positive correlation with the DTTv, but the opposite was found with the DTTm. An aerodyne high-resolution aerosol mass spectrometer (HP-AMS) was deployed to probe the chemical properties of the water-soluble organic matter (WSOA). Positive matrix factorization (PMF) coupled with multiple linear regression was used to obtain the relative source contributions to the DTT activity for the WSOA in the PM2.5. The results showed that the sensitivity sequences of the DTTv to the WSOA sources were oxygenated organic aerosol (OOA) > biomass burning OA (BBOA) > hydrocarbon-like OA (HOA) in the spring and HOA > nitrogen-enriched OA (NOA) > OOA in the summer. The PMF suggested the highest contribution from traffic emissions to the DTTv of the PM2.5 in both seasons. Our findings point to the importance of both organic components from secondary formation and transition metals to adverse health effects in this region. This study can provide an important reference for adopting appropriate public health policies regarding the detrimental outcomes of exposure to PM2.5.

Manufacturing Technology of Multilayer Metal Filters

The article presents methods for obtaining micro-holes in the manufacture of fine metal filter elements. The analysis of the results of experimental studies of filter samples with holes made by electron beam and electroerosion perforation methods is carried out. The advantages of using multilayer structures in the manufacture of filters are substantiated. The research works carried out contribute to improving the manufacturability of products of new generations of technology, which is important for mechanical engineering.