Double-layer Filter Research Articles

Terahertz bandpass and bandstop filter based on the babinet complementary metamaterials

In this study, we experimentally investigate the terahertz (THz) bandpass and bandstop filters based on the elliptical Babinet complementary structure, including an elliptical hole structure (EHS) and an elliptical ring structure (ERS). The experimental results indicate that the monolayer structure exhibits an obvious polarization selectivity with consistent filtering curves under TE and TM mode excitation, but the spectral line has an apparent shift of 0.1 THz. Based on Babinet's principle, the filtering mode matching is experimentally verified between bandpass and bandstop under a 90° change in polarization. Furthermore, we propose a double-layer filter by integrating EHS and ERS on both sides of the silicon substrate, and realize the bandpass and bandstop filtering simultaneously. The simulation results show that the isolation degree of bandpass and bandstop filtering has a maximum of nearly 40 dB based on the angle-tunable filtering performance, and the Q-value of the filter is further improved than that of the single-layer structure. The filter designed based on the Babinet principle has the advantages of simple structure, easy processing, and sharper filtering effect, and shows great applications in THz communication, imaging, and sensing systems.

Electrospun membrane of PLA/calendula with improved UV protection and stable filtration performance

The “dual carbon” strategy and the severe air pollution problem have spurred the development of environmentally friendly functional filters. However, the performance stability of degradable polymers under ultraviolet (UV) irradiation needs to be explored and addressed. Loading natural small molecules onto electrospun fibers can enhance their functionality and sustainability. This study explores the use of calendula extract to protect polylactic acid electrospun fibers from UV degradation and provide antibacterial properties. A double-layer filter was created using straightforward sequential electrospinning. Only one-third of the fiber membrane's thickness contains drugs, resulting in an 88 % inhibition rate against Staphylococcus aureus. Its UV protection capability has been significantly enhanced. The calendula filters exhibited a tensile strength loss rate of only 23 %, compared to 30 % for the unmodified filters. Furthermore, the calendula extract altered the morphology and porous structure of the fibers, leading to an enhancement in the stable filtration efficiency of the membrane. It maintains a filtration efficiency of over 99 % at a flow rate of 32–85 L/min. This study has enhanced the stable filtration capacity of biomass filters and showcased their potential for UV protection and antibacterial applications.

The influence of nozzle height on the cleaning performance of inner cone double-layer filter cartridges with different cone radius through the distributional characterization of peak static pressure

The inner cone double-layer filter cartridges have the capability to guide the flow, which can optimize the airflow distribution inside the cartridge and reduce the cartridge's incomplete cleaning. However, the selection of different cone radius and nozzle heights can affect the cartridge's cleaning performance. More thorough investigations of the static pressure distribution properties within double-layer cartridges are required to improve their design and optimization. The results show that double-layer cartridges' peak static pressure at different nozzle heights has a similar distribution law. Peak static pressure increases progressively with cartridge height in the middle and lower sections (OM3-OM5, IM2-IM5), with the lower section having a larger peak static pressure. The cleaning performance of cartridges with a cone radius of R ≥ 80 mm is little impacted by the nozzle height. The stability of the cartridge's cleaning performance improves and then deteriorates as the cone radius increases, with the best cleaning effect and stability reached at R = 80 mm. In practical applications, double-layer filter cartridges with larger cone radius should be considered.

Influence of the inner diameter of the bottom plate on the cleaning performance of double-layer filter cartridges

Dust collectors are used in various industries to separate pollutants from the air. Filter cartridge dust collectors are favored for their stability and small footprint. However, conventional cleaning techniques make it difficult to solve the problem of incomplete cleaning of filter cartridges, which require frequent replacement. Inner cone double-layer filter cartridges are utilized to improve the incomplete cleaning of filter cartridges. The size of the inner diameter (ID) of the bottom plate is one of the main factors affecting the cleaning performance of the double-layer filter cartridge. Double-layer filter cartridges' inside flow field is investigated by numerical simulation in this work. Selection of evaluation indexes such as peak static pressure and comprehensive pressure to assess cleaning performance and analyze the effect of ID on cleaning performance. It was shown that increasing ID could optimize the upper section of the filter cartridges' static pressure distribution. Both larger (ID = 160 mm) and smaller (ID = 40 mm) filter cartridges ID possessed better bottom static pressure accumulation capacity. As the inner diameter of the bottom plate decreases, the cleaning performance increases and then decreases, and the best results were obtained at an ID of 140 mm, with a PC of 1175 Pa. Notably, IDs exceeding 160 mm have a significant negative impact on the cleaning performance of the filter cartridges.

Effect of cone radius on the pulse-jet cleaning performance of double-layer filter cartridges (DL-FC)

Recently, double-layer filter cartridges (DL-FCs) have been proposed to reduce incomplete cleaning. In this study, with the help of numerical simulation, the effect of cone radius (R) on the cleaning performance of DL-FCs was investigated by varying the radius. The results indicate that reducing the radius of the cone will expand the zones on the upper part of the DL-FC that have been under low-pressure for a long time. During the pulse-jet cleaning process, five vortexes are mainly generated on one side of the DL-FC. Vortex 1 has the most significant impact on the DL-FC. Vortex 1 not only causes the pressure in the area of the DL-FC near the baffle to be too small and in a low-pressure state for an extended period, but also makes the pressure curve of the measured points on the surface of the FC have a V-shape depression. The increase of the cone radius can improve the negative impact caused by Vortex 1 on the FC. In addition, the comprehensive pressure (PC) was introduced as an evaluation index for the pulse-jet cleaning performance of the FC. As the radius of the cone decreases from 100 mm to 20 mm, the comprehensive pressure of the DL-FC first increases and then decreases. In this study, when the distance of the top of the inner cone from the baffle H = 0 mm and cone radius R = 80 mm, the comprehensive pressure of the DL-FC is the highest. The overall comprehensive pressure of the outer filter cartridge (O-FC) and the DL-FC were improved by 92.3 % and 90.0 %, respectively.

Multi-level structured polylactic acid electrospun fiber membrane based on green solvents for high-performance air filtration

Particle matter (PM) pollution seriously threatens public health as it can combine with viruses and heavy metals to enter the human body and cause various diseases. Electrospun polymer fiber membranes, especially biodegradable materials such as polylactic acid, have great potential in PM filtration. However, most polylactic acid fiber membranes are imbalanced between filtration efficiency and resistance. Porous and bead-like fibers offer higher filtration efficiency and are expected to address these challenges with their larger specific surface area. Nonetheless, this structure may compromise the mechanical strength of the fiber membrane, thereby affecting the stability of gas purification and separation. Additionally, the significant volatilization of solvents during solution electrospinning can result in environmental concerns. Here, we prepared a double-layer filter with beads and cracks using a green mixed solvent of N, N-dimethylacetamide and dimethyl carbonate. The difference in the volatilization rate of mixed solvents increases the roughness of the membrane surface and enhances the adsorption of PMs. The structural difference between the two layers of membranes enables graded filtration of particles, further reducing pressure drop. Moreover, the entanglement at the interfaces enhances the mechanical properties of the bilayer membrane. It is worth mentioning that the design of the double-layer membrane improves the overall hydrophobicity and has practical application potential.

Effect of double-layer filter cartridge with an inner cone on the pulse-jet cleaning performance of cartridge dust collectors

The double-layer filter cartridge with an inner cone was designed to improve the pulse-jet cleaning performance of the filter cartridge. The flow field and pressure variation of the double-layer filter cartridge were investigated with the help of numerical simulations. The pressure at the inner wall of the filter cartridge was explored by varying three parameters: the height of the cone (h), the diameter of the cone (D) and the distance between the top of the inner cone and the baffle (H). The results showed that for conventional filter cartridge, influenced by the angle of the pulse-jet, the airflow got sufficiently expanded after the pulse-jet airflow reached the middle of the filter cartridge, and the pressure at the top of the filter cartridge was slight. It was found that the cone diameter and the distance between the top of the inner cone and the baffle had a significant effect on the pressure of the inner wall of filter cartridges, with the distance between the top of the inner cone and the baffle had the most excellent effect and the height of the cone had the slightest effect. Compared with conventional filter cartridges, the peak pressure at measurement point O1 of the optimized double-layer filter cartridge (h = 120 mm, D = 160 mm, H = 0 mm) was increased by 543.3%. The coefficient of variation (C.V.) of the pressure at the inner wall of the outer filter cartridge was significantly reduced, indicating that the pulse-jet cleaning effect of the optimized double-layer filter cartridge was significantly improved. This study can provide theoretical support to reveal the mechanism of pulse-jet cleaning of double-layer filter cartridges and technical support to optimize the design of double-layer filter cartridges.

Physiological and Germination Responses of Muskmelon (Cucumis melo L.) Seeds to Varying Osmotic Potentials and Cardinal Temperatures via a Hydrothermal Time Model.

Climatic changes have a direct negative impact on the growth, development, and productivity of crops. The water potential (ψ) and temperature (T) are important limiting factors that influence the rate of seed germination and growth indices. To examine how the germination of seed responds to changes in water potential and temperature, the hydrotime model and hydrothermal model (HTT) have been employed. The HTT calculates the concept of germination time across temperatures, between Tb-To, with alteration, and between Tb-Tc, in supra-optimal ranges. The seeds of Cucumis melo L. were germinated in the laboratory for a hydro-thermal time experiment. Seeds were sown in Petri dishes containing a double-layered filter paper at different osmotic potentials (0, -0.2, -0.4, -0.6, and -0.8 MPa) by providing PEG 6000 (drought stress enhancer) at different temperatures (15, 20, 25, 30, and 35 °C). The controlled replicate was treated with 10 mL of distilled water and the rest with 10 mL of PEG solution. Results indicated that the seed vigor index (SVI-II) was highest at 15 °C with 0 MPa and lowest at 30 °C with -0.2 MPa. However, the highest activity was shown at 15 °C by catalase (CAT) and guaiacol peroxidase (GPX) at (-0.6 MPa), while the lowest values of CAT and GPX were recorded for control at 35 °C with -0.8 MPa at 35 °C, respectively. Germination energy was positively correlated with germination index (GI), germination percentage (G%), germination rate index, seed vigor index-I (SVI-I), mean moisture content (MMC), and root shoot ratio (RSR) and had a negative correlation with mean germination rate, percent moisture content of shoot and root, CAT, superoxide dismutase, peroxidase ascorbate peroxidase, and GPX. In conclusion, thermal and hydrotime models correctly predicted muskmelon germination time in response to varying water potential and temperature. The agronomic attributes were found to be maximum at 30 °C and minimum at 15 °C.

Single-Layer and Double-Layer Filtration Materials Based on Polyvinylidene Fluoride-Co-hexafluoropropylene Nanofibers Coated on Melamine Microfibers.

In this work, we demonstrate selected optimization changes in the simple design of filtration masks to increase particle removal efficiency (PRE) and filter quality factor by combining experiments and numerical modeling. In particular, we focus on single-layer filters fabricated from uniform thickness fibers and double-layer filters consisting of a layer of highly permeable thick fibers as a support and a thin layer of filtering electrospun nanofibers. For single-layer filters, we demonstrate performance improvement in terms of the quality factor by optimizing the geometry of the composition. We show significantly better PRE performance for filters composed of micrometer-sized fibers covered by a thin layer of electrospun nanofibers. This work is motivated and carried out in collaboration with a targeted industrial development of selected melamine-based filter nano- and micromaterials.

NaClO-based rapid sand filter in treating manganese-containing surface water: Fast ripening and mechanism

Recently, seasonal manganese contamination in the surface water is capturing ever-increasing attention and has posed significant challenges to the safety of water supply in the conventional drinking water treatment plants. This study aimed to develop new strategies to enhance the manganese removal by the sand filter. The synergistic effects of filter material type, filter layer thickness, filtration rate, and NaClO addition on the manganese removal performance, were systematically investigated. The results indicated that modified zeolite exerted the highest adsorption capacity (5.200 mg/g) for manganese. Introducing the NaClO oxidation would effectively improve the manganese removal efficiency (from 32 % to 97 %) by the modified zeolite filter compared to the control system at the filtration rate of 8 m/h, owing to the fast formation of catalytic oxidation capability. Accordingly, the effective layer thickness of modified zeolite can be shortened from 100 cm to 10–20 cm to engineer a double-layer filter consisting of both a thin modified zeolite layer and a thick natural quartz sand layer. Besides, NaClO involvement would neutralize the adverse effects of manganese removal caused by the filtration rate increase, and facilitate the formation of auto-catalytic manganese oxides (MnOx) with rough, heterogeneous, and porous surface morphology, as well as numerous tremella-like and sponge-type structures, which was related to the fast removal of manganese. These findings are full of significance in developing simple, practical, and cost-effective strategies for seasonal manganese contamination.

An approach to dual-energy contrast-enhanced spectral mammography (DE-CESM) using a double layer filter: dosimetric and image quality assessment

Dual-energy contrast-enhanced spectral mammography (DE-CESM) is a recently developed advanced technique in digital mammography that uses an iodinated intravenous contrast agent to assess tumor angiogenesis. The aim of this study was to investigate the diagnostic potential of DE-CESM recombined images in terms of radiation dose and image quality. A 50% fibroglandular—50% adipose, custom-made phantom with iodine inserts of 1.0 mgI cm−3, 2.0 mgI cm−3, 4.0 mgI cm−3 was used for the estimation of mean glandular dose (MGD) and the image quality. Low-energy (LE) images were acquired with the W/Rh, W/Rh + 0.01 mm Cu and W/Rh + 0.5 mm Al while high energy images (HE) are acquired with the W/Rh, W/Rh + 0.06 mm Ba, W/Rh + 0.01 mm Cu, and W/Rh + 0.03 mm Ce anode filter combinations. The total MGD was reduced up to a maximum from 1.75 mGy to 1.45 mGy by using Rh + 0.01 mm Cu double-layer filter for both LE and HE imaging of 50 mm, standard 50% fibroglandular phantom compared to Rh single-layer filter with W target. The minimum total MGD reduction (1.69 mGy) was observed when Rh + 0.5 mm Al was used for LE and Rh + 0.06 mm Ba was used for HE exposure. The image quality was comparable with the single-layer filter. The use of W/Rh + 0.01 mm Cu or W/Rh + 0.5 mm Al as target/filter combination for LE exposure and W/Rh + 0.01 mm Cu for HE exposure can reduce the additional radiation dose delivered by DE-CESM without degrading the image quality.

Influence of double layer filter on mean glandular dose (MGD) and image quality in low energy image of contrast enhanced spectral mammography (LE-CESM)

IntroductionThe aim of this study was to evaluate mean glandular dose (MGD) and image quality in low energy imaging from contrast-enhanced spectral mammography (CESM) when using double-layer filtration. MethodologyA dedicated phantom was used to quantitatively estimate the MGD and image quality. The target slab of the phantom consisted of three iodine coins having a concentration of 1.0 mgI/cm3, 2.0 mgI/cm3, 4.0 mgI/cm3, a 100% adipose equivalent coin and a 100% glandular equivalent coin. The phantom was exposed using a semiautomated function at 28 k, 30 kV and 32 kV. MGD. Contrast to noise ratio (CNR) and figure of merit (FOM) were estimated for Mo/Rh, Mo/Rh + Cu, Mo/Rh + Al and Mo/Rh + Cd combinations using three breast equivalent compositions. ResultsMGD was reduced up to a maximum of 1.03 mGy from 1.17 mGy for 100% adipose tissue. 1.18 mGy from 1.34 mGy for 50% glandular tissue and 1.39 mGy from 1.72 mGy for the 100% glandular phantom when using double-layer filtration. All of the above-mentioned results were obtained for the 50 mm phantom using 32 kV. CNR and FOM values were not significantly reduced with a double-layer filter when compared to a single-layer filter. ConclusionThe present study concluded that Mo/Rh + Cu is the best combination to reduce the MGD significantly when compared to Mo/Rh + Al or Mo/Rh + Cd. Mo/Rh + Cu also achieved optimal image quality when compared to the Mo/Rh single filter combination. Implications of practiceThe use of a double-layer filter in low energy imaging of CESM results in a significant reduction in MGD without degrading the quality of the image.

A Metal-free ionic liquid Dual-ion battery based on the reversible interaction of 1-Butyl-1-Methylpyrrolidinium cations with 1,4,5,8-Naphthalenetetracarboxylic dianhydride

The strong self-discharge reaction is one of the key factors limiting the practical use of dual-ion batteries, which leads to low coulombic efficiency and discharge capacity loss. It is of great significance to effectively reduce the self-discharge effect through redox reactions between organic electrodes and electrolytes. Herein, a dual-ion battery study that uses 1,4,5,8-naphthalenetetracarboxylic dianhydride as the anode and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide as the electrolyte is conducted. Due to the introduction of organic materials, the storage mechanism of cations on the anode is changed, which weakens the self-discharge effect. The battery shows a low self-discharge rate of 6.12% h−1 and a high discharge capacity of 114 mAh g−1. The voltage declines by only 0.14 V after resting for 15 h due to the strong redox reaction between Pyr14+ cations and the CO groups of NTCDA. Meanwhile, a double-layer filter paper system with small porosity is used to improve the cycle performance of the battery.

Simultaneous removal of particulates and NO by the catalytic bag filter containing V2O5-MoO3/TiO2

V2O5-MoO3/TiO2 based catalytic bag filters were developed for the simultaneous removal of particulates and NO in the temperature range of 200–250 °C. Good denitrification activity, dedust efficiency as well as high adhesion strength in the temperature range of 200–250 °C was exhibited. The study of catalyst powder for coating revealed that the increased V and Mo content in catalyst can elevate the low-temperature activity, and the chosen V10Mo10 sample for coating showed the best activity with 100% NO conversion at just 180 °C. The further research on catalytic bag filter found the low ratio of PTFE, high loading and long residence time (e.g., low filtration velocity or double layer filter) may help to achieve high DeNOx efficiency. The best performance was obtained with above 80% NO conversion at 200–250 °C even in the presence of SO2/H2O and 99.9% dust collection efficiency on the condition of 500 g/m2 loading, 10% PTFE, 0.5 m/min filtration velocity and double layers of filter, which demonstrated great feasibility for industrial application.

Miniaturized High-Performance Cube-Shaped Filter Made Up of Quasi-TM010 Mode Dielectric-Loaded Cavities

In this paper, a compact quasi-TM 010 mode dielectric-loaded bandpass filter with 8th-order pseudoelliptic filtering function and symmetric positioning of 4 transmission zeros is analyzed and designed. The resonant frequency and field components of quasi-TM 010 mode of a cylindrical dielectric resonator (DR) were first calculated and simulated. Compared to the pure TM 010 mode, the unloaded Q factor of quasi-TM 010 mode can increase by 3000 to more than 8000 and then the dimensions of the single DR at 2.595GHz are π×34 2 ×20 mm 3 (using e r = 45). The magnetic coupling and electric coupling between dielectric-loaded cavities are studied and the dielectric window is innovatively proposed to generate electric coupling and to avoid the use of metallic probes that are cumbersome to assemble. In final, a quasi-TM 010 mode double-layer filter with two pairs of symmetric transmission zeros is designed according to the cubic-like topology and fabricated and tested which exhibits close agreements between the simulated and measured results demonstrating the advantages of low insertion loss, very close-to-band rejections and compact configuration. The proposed filter has great potential for development in 5G mobile communication systems and microwave radar communication systems.

The Extract Obtained from Two Radish Cultivars (Raphanus sativus L. and Raphanus sativus L. var. radikula) Using Liquid Nitrogen Is Germination of Sterile Oats (Avena sterilis Subsp. sterilis) and Allelopathic Effect on Seedling Growth

The purpose of this study is to determine the allelopathic effects of extracts obtained by using liquid nitrogen from the plant of Antep radish (Raphanus sa-tivus L.) and little radish (Raphanus sativus L. var. radikula) on germination and seedling growth of sterile oats. The experiments were carried out in six groups with root, stem and root stem mixed extracts of radish plants (Antep and little radish). A novel method that we developed based on the principle of liquid nitrogen crushing was used for extraction. According to this method, Antep radish and little radish plant parts were frozen with liquid nitrogen aid and then crushed to powder. These powders obtained were stored at ？20？C for nine months until the experiments were established. The aqueous solutions prepared at specific concentrations (0%, 1%, 2%, 4%, 8%, 16%) from the ob-tained radish powders were applied as 5 ml to per each petri dishes contain 10 seeds on Whatman No: 1 double layer filter paper. Experiments were carried out in six replicates for each concentration. The prepared petri dishes were kept in the incubator at 15？C for 15 days. At the end of the experimental period, the number of germination of the seeds of sterile wild oat plant was evaluated by measuring the length of seedling root and stem. As a result, as the concentra-tion of allelopathic solutions increased in all experimental groups, the number of germination and root and stem lengths of sterile wild oats decreased. Alt-hough allelopathic effects in all three experimental groups were observed in terms of germination number and seedling lengths, the most significant effects were observed in the results of Antep radish root experiments. In this experi-ment group, the inhibition rate of root and stem length of weed seeds at a con-centration of 16% were 86% and 82%, respectively, when compared to the control. In addition, the germination number was reduced by 74.36% in the seeds at the highest concentration compared to the control. As a result of the study, it was determined that samples of radish plant crushed with liquid nitro-gen were stored for a long time and showed high allelopathic effect on sterile wild oats plant.

Free-standing double-layer terahertz band-pass filters fabricated by femtosecond laser micro-machining.

We report on the fabrication and transmission properties of free-standing single-layer and double-layer THz bandpass filters. These filters are fabricated on aluminum foils using femtosecond laser micro-machining. The aluminum foils are periodically patterned with cross apertures with a total area of 1.75×1.75 cm2, also known as frequency-selective surfaces. Their terahertz transmission properties were simulated using the FDTD method and measured using a time-domain terahertz spectroscopy system. The simulation results agree with the measurements results very well. The performance of single-layer bandpass filters is as good as the commercial equivalents on the market. The double-layer filters show extraordinary transmission peaks with changing spacing between the two layers. We show the contour map of the electric field distribution across the apertures, and ascribe the new transmission peaks to the interference and coupling of surface plasmon polaritons between the two layers.

Fabrication of highly hydrophilic filter using natural and hydrothermally treated mica nanoparticles for efficient waste oil-water separation

For the effective oil/water separation, a novel superhydrophilic (underwater superoleophobic) filter is fabricated with the naturally and hydrothermally treated mica particles. To fabricate a double layered filter, hydrothermally treated mica particles were initially electrodeposited on a stainless steel mesh and a natural mica particles were sprayed on the first hydrothermally deposited mica layer. The double layered mica coated membrane showed superamphiphilic and superhydrophilic/superoleophobic (contact angle >159°) characteristics in air and underwater respectively. The membrane can separate range of oil-water mixtures with oil/water separation efficiency over ∼99%. Properties of double layered mica membrane were investigated and noted that the surface adhesion properties of mica is enhanced by the hydrothermal treatment of mica and the higher roughness of the mica layer is maintained by the natural mica.

Очистка аспирационных пылегазовых потоков при производстве полиэтилена фильтром из гранулированного полиэтилена

The article considers the closed dust gas cleaning system after drying in the production of polyethylene under pressure. Pellets of polyethylene are used as a filter material in double layer filter and it allows to return filter materials as a raw in production. The developed scheme of double layer filter with a regeneration system is presented in the article. The authors propose regression equations allowing to predict the efficiency of dust collection for the present design.

In-vivo dosimetry in 3D conformal radiotherapy of breast and head and neck cancer

In-vivo dosimetry in 3D conformal radiotherapy of breast and head and neck cancer