Particle Capture Research Articles

Influence of meteorological variables and air pollutants on measurements from automatic pollen sampling devices

This study examines the influence of meteorological factors and air pollutants on the performance of automatic pollen monitoring devices, as part of the EUMETNET Autopollen COST ADOPT-intercomparison campaign held in Munich, Germany, during the 2021 pollen season. The campaign offered a unique opportunity to compare all automatic monitors available at the time, a Plair Rapid-E, a Hund-Wetzlar BAA500, an OPC Alphasense, a KH-3000 Yamatronics, three Swisens Polenos, a PollenSense APS, a FLIR IBAC2, a DMT WIBS-5, an Aerotape Sextant, to the average of four manual Hirst traps, under the same environmental conditions. The investigation aimed to elucidate how meteorological factors and air pollution impact particle capture and identification efficiency.The analysis showed coherent results for most devices regarding the correlation between environmental conditions and pollen concentrations. This reflects on one hand, a significant correlation between weather and airborne pollen concentration, and on the other hand the capability of devices to provide meaningful data under the conditions under which measurements were taken. However, correlation strength varied among devices, reflecting differences in design, algorithms, or sensors used. Additionally, it was observed that different algorithms applied to the same dataset resulted in different concentration outputs, highlighting the role of algorithm design in these systems (monitor + algorithm).Notably, no significant influence from air pollutants on the pollen concentrations was observed, suggesting that any potential difference in effect on the systems might require higher air pollution concentrations or more complex interactions. However, results from some monitors were affected to a minor degree by specific weather variables.Our findings suggest that the application of real-time devices in urban environments should focus on the associated algorithm that classifies pollen taxa. The impact of air pollution, although not to be excluded, is of secondary concern as long as the pollution levels are similar to a large European city like Munich.

Molecular Dynamics Study on the Capture of Aluminum Particles by Carbon Fibers during the Propagation of Aluminum-Based Energetics

Molecular Dynamics Study on the Capture of Aluminum Particles by Carbon Fibers during the Propagation of Aluminum-Based Energetics

Relating ciliary propulsion morphology and flow to particle acquisition in marine planktonic ciliates I: the tintinnid ciliateAmphorides quadrilineata

AbstractThe marine tintinnid ciliate Amphorides quadrilineata is a feeding-current feeder, creating flows for particle encounter, capture and rejection. Individual-level behaviors were observed using high-speed, high-magnification digital imaging. Cells beat their cilia backward to swim forward, simultaneously generating a feeding current that brings in particles. These particles are then individually captured through localized ciliary reversals. When swimming backward, cells beat their cilia forward (=ciliary reversals involving the entire ring of cilia), actively rejecting unwanted particles. Cells achieve path-averaged speeds averaging 3–4 total lengths per second. Both micro-particle image velocimetry and computational fluid dynamics were employed to characterize the cell-scale flows. Forward swimming generates a feeding current, a saddle flow vector field in front of the cell, whereas backward swimming creates an inverse saddle flow vector field behind the cell; these ciliary flows facilitate particle encounter, capture and rejection. The model-tintinnid with a full-length lorica achieves an encounter rate Q ~29% higher than that without a lorica, albeit at a ~142% increase in mechanical power and a decrease in quasi-propulsive efficiency (~0.24 vs. ~ 0.38). It is also suggested that Q can be approximated by π(W/2 + l)2U, where W, l and U represent the lorica oral diameter, ciliary length and swimming speed, respectively.

Relating ciliary propulsion morphology and flow to particle acquisition in marine planktonic ciliates II: the oligotrich ciliate Strombidium capitatum

Abstract The marine oligotrich ciliate Strombidium capitatum is a cruise-feeder, relying on ciliary motion and propulsion flow to individually detect and capture particles. High-speed, high-magnification digital imaging revealed that the cell swims forward by sweeping its anterior adoral membranelles (AAMs) backward, achieving a mean path-averaged speed of U = 1.7 mm s−1 (31 cell-lengths per second). Particle detection occurs through either hydrodynamic signal perception or ciliary contact perception, with a mean reaction distance of R = 20.4 μm. While executing a ciliary reversal of AAMs to handle and capture a perceived particle, the cell coordinates the ciliary motion of ventral adoral membranelles (VAMs, the “lapel”) with the ciliary reversal of AAMs (the “collar”), causing a sudden halt of cell motion, thereby functioning as a motion “brake” that is crucial for effective particle capture. The encounter rate with small prey particles is calculated using πR2U (~8.0 μL h−1, equivalent to ~ 3.5 × 106 cell volumes per day). Based on hydrodynamic modeling results, it is hypothesized that spatial structures of the flow velocity vector and acceleration fields in front of the swimming cell are essential for pushing an embedded particle forward, creating a strong enough slip velocity and hydrodynamic signal for prey perception, even for a neutrally buoyant small particle.

Sequential Computer Simulation of H-minus Ion Dynamics from Source to RFQ Exit with Beam Rotation

An end-to-end simulation of the beam dynamics in the system of extraction, beam transportation and the first section of the accelerator (RFQ) is carried out. The proposed method of modeling the dynamics of ions from the source to the exit from the RFQ made it possible to quickly and efficiently change the parameters of the matching system depending on the final results of the beam passing into the RFQ. A system for matching a beam of negative hydrogen ions has been developed and optimized, which makes it possible to rotate the beam to block the propagation of cesium into the accelerator channel and to match the beam with RFQ. As a result of optimization of the matching channel, it is possible to obtain an emittance increase in RFQ of no more than 25 % for 90 % of the beam fraction, while the capture of beam particles in the acceleration mode is 98 % of the injected beam. The increased drifts in the matching system leave enough space for the placement of diagnostic equipment, a vacuum system and a beam correction system. The dependence of the beam dynamics in the RFQ on the charge distribution over the beam cross section at the output of the matching channel is established.

4D Printed Soft Microactuator for Particle Manipulation via Surrounding Medium Variation.

Soft actuators have assumed vital roles in a diverse number of research and application fields, driving innovation and transformative advancements. Using 3D molding of smart materials and combining these materials through structural design strategies, a single soft actuator can achieve multiple functions. However, it is still challenging to realize soft actuators that possess high environmental adaptability while capable of different tasks. Here, the response threshold of a soft actuator is modulated by precisely tuning the ratio of stimulus-responsive groups in hydrogels. By combining a heterogeneous bilayer membrane structure and in situ multimaterial printing, the obtained soft actuator deformed in response to changes in the surrounding medium. The response medium is suitable for both biotic and abiotic environments, and the response rate is fast. By changing the surrounding medium, the precise capture, manipulation, and release of micron-sized particles of different diameters in 3D are realized. In addition, static capture of a single red blood cell is realized using biologically responsive medium changes. Finally, the experimental results are well predicted using finite element analysis. It is believed that with further optimization of the structure size and autonomous navigation platform, the proposed soft microactuator has significant potential to function as an easy-to-manipulate multifunctional robot.

Charge Protection in Electret Air Filtration Nonwoven Materials

AbstractNonwoven media used as electret air filters are often embedded with charges to improve particle capture efficiency. These charged filters are invariably exposed to low surface tension fluids such as oils and alcohols leading to charge loss. In this study, filtration media are endowed with charge protection through increased surface repellency using melt additives that can migrate to the surface during processing. Nonwovens containing fluorochemical melt additives are produced, and examined to determine the relationship between surface chemistry, isopropyl alcohol (IPA) repellency, resultant charge retention, and filtration characteristics. Surface fluorine/carbon (F/C) ratios of ≈0.2 are sufficient to protect filtration performance from vapor discharging methods. Samples with bulk additive loadings of 1.2% or higher are found to achieve the necessary repellency to resist discharging independent of the migration state of the sample, while samples loaded at the 0.6% level required sufficient migration to achieve the requisite F/C ratio of 0.2 in order to be protected. Samples that achieved the necessary surface chemistry to provide significant IPA repellency retained > 80% of electret charge and corresponding filtration performance. These results have special significance in the design of filtration media relevant in global healthcare and other industrial settings.

Morphologically reconfigurable magnetic micropillar arrays using acoustic streaming for particle capture and droplet manipulation

The accurate and efficient manipulation of particles and droplets is crucial for the fields of disease diagnosis, target drug delivery, and sample purification, specific microstructure-based particle and droplet manipulation have been widely utilized in bioassays. However, current techniques are mainly based on the fixed microstructures, which is extremely difficult to achieve dynamic modulation by adjusting microstructure morphology and excitation conditions. Herein, we present a novel particle capture and droplet manipulation methodology by using morphologically reconfigurable magnetic micropillar arrays incorporate with acoustic streaming effects, which enables reconfigurable particle capturing, cargo transportation, and droplet manipulation. The mechanism is to assemble NdFeB magnetic powders by magnetic gradient fields to form morphologically variable magnetic micropillar arrays with porous surfaces, and the localized acoustic streaming effects generated by surface acoustic waves (SAWs) enable micropillar arrays to capture nearby particles onto the surfaces or to drive perturbations in droplets in the vicinity. To demonstrate the capabilities of this technology, we have achieved the high-volume acoustofluidic particle capture and loading (0.214 MCF), targeted complex maze navigation, efficient droplets manipulation (≤ 3.96 mm/s), and acoustofluidic mixing acceleration (≤ 2.5 s). Therefore, this technique enables reconfigurable and versatile manipulation of particles and droplets in biomedical applications.

Photo-responsive polypropylene/zinc oxide/polydopamine-TEMPO composite membranes with light-induced self-sterilization

Face masks play a pivotal role in preventing infection transmission. However, the capture of infection-sourced particles in face masks poses challenges related to reuse, necessitating proper disposal. We developed a self-sterilizable polypropylene-based membrane for face masks to address challenges associated with infection transmission prevention. The membrane, created using 3D printing, underwent functionalization with zinc oxide (ZnO) and polydopamine (PDA)-TEMPO to achieve broad-spectrum light absorption and facilitate self-sterilization through photocatalytic and photothermal effects upon light exposure. The hydrophobic surface (water contact angle: 133 ± 2 °) minimized moisture accumulation, and the membrane exhibited robust mechanical properties, including shear strength (1.25 ± 0.5 kPa) and peel resistance strength (112.8 ± 11.2 kPa). The evaluation demonstrated stability in airflow (0 to 500 cm3/s) and excellent aerosol filtration efficiency (94.8 ± 0.6 %) for particles (PM 0.3, PM 2.5, PM 10), comparable to commercial masks. The membrane showed antibacterial efficacy over five uses in a simulated respiratory environment. Safety assessments confirmed biocompatibility through cytocompatibility and skin irritation assays. In conclusion, this membrane offers efficient filtration and photo-triggered sterilization, presenting a promising solution for next-generation face masks to address concerns related to reuse, disposal, and infection control.

An analytical model-based assessment of Wet Electrostatic Scrubbing for mitigating fine and ultrafine particles emissions in domestic biomass boilers

This paper proposes the general design of a Wet Electrostatic Scrubber aimed at mitigating fine and ultrafine particles emissions from domestic heating boilers. The design is based on particle capture modelling supported by specific experiments and technical literature information. Results indicate up to 96.6% removal efficiency, consuming 1.2 kg/h of water and 0.3 W per 1 m3/h of gas treated. Comparative analysis highlights the balanced performance of Wet Electrostatic Scrubber in particle capture, energy and water usage, pressure drop, and space occupancy, with the additional benefit of more efficient absorption of gas pollutants.

Formulation and Evaluation of Lipid-based Nanoformulation of Itraconazole

The powdered form of itraconazole is white, flavorless, and stable, but it dissolves slowly in water. In comparison to palmitic acid, stearic acid has a stronger affinity (2.57), as shown by the partition coefficient test. UV-visible spectra analysis reveals critical compound insights. Fourier-transform infrared (FTIR) identifies significant peaks in itraconazole and related compounds. tween 80 is selected for solid lipid nanoparticles (SLN) based on their appearance. Optimization using 0.5% w/v tween 80 yielded better particle capture. Thermal analyses display distinctive characteristics of itraconazole, palmitic acid, and polyvinyl alcohol. Viscosity studies mirror tear film behavior. Transmission electron microscope (TEM) images demonstrate SLN’s potential ocular application without irritation. Antifungal studies exhibit effective inhibition of Candida albicans and Aspergillus flavus growth. SN-7 reveals strong encapsulation efficiency, mean vesicle size, and sustained drug release over 12 hours. Pharmacokinetic studies shed light on SLNs’ influence on drug absorption and distribution, indicative of potential in drug delivery systems. These findings offer promising prospects in formulating enhanced drug delivery mechanisms and understanding their impact on drug pharmacokinetics. High-performance liquid chromatography (HPLC) analysis confirmed SN-7’s singular peak at 6.59 minutes. Both formulations showcased skin penetration and stability over three months under varied conditions. Skin irritation tests on rats indicated minimal reactions, affirming low irritancy, which is crucial for patient comfort and acceptance in topical drug delivery. These assessments ensure safety and effectiveness in treating fungal infections.

Biomass-based renewable, eco-friendly nanofiber membrane: Large-scale fabrication and application in PM0.3 capture and oily wastewater purification

Biomass-based poly (trimethylene 2,5-furandicarboxylate) (PTF) was synthesized by the simple and low-cost direct esterification method. The high number-average molecular weight (Mn) of about 39.6 kDa was achieved for PTF with a polydispersity index (PDI) of 2.0, which was suitable for spinning. The electrospun PTF nanofiber membranes were fabricated firstly and displayed adjustable diameters, excellent mechanical properties (lifting 550 g weight, foldability) and large-scale preparation potential (area of 100 cm × 50 cm). More impressively, high initial surface potential (13.5 kV) was found for the electrospun in-suit electret membranes, which facilitated the capture of ultrafine PM particles. Subsequently, the PTF membrane showed exceptional particle capture capability with a filtration performance of 99.96 %, low pressure drops of 78 Pa, and a satisfactory quality factor of 0.1 Pa−1. PTF filters also demonstrated long-term service capability for purifying high PM2.5 concentration smoke (15 cycles, 55 min), and could be flexibly introduced into various practical scenarios. Additionally, based on the selective oil/water wettability of PTF membranes, which showed outstanding separation effects of oily wastewater(＞99.88 %, 15 cycles). Therefore, the development and application of the PTF nanofibers provided a sustainable alternative for separation/purification and various fields in the future.

Evaluation and prediction of fibrous filters' operating performance in residential fresh air system

Fibrous filters play a crucial role in determining indoor air quality and protect people from bacteria, particulates, and viruses such as COVID-19. However, there is a lack of comprehensive research on methods for effectively evaluating and predicting the operating performance of these filters. In this study, we conducted laboratory and field tests on coarse (G4) and medium (F9 or F7) filters from four different brands to assess both their initial and operating performance. We discovered that a fluffy fiber structure in coarse filters could achieve an impressive threefold increase in dust holding capacity (DHC) compared to normal filters. Utilizing initial pressure drop, initial particle capture efficiency, and DHC, we introduced a new quality factor (QF) that integrates these parameters to evaluate the filter's long-term performance. This approach addresses the limitations of traditional quality factor, which neglects DHC and tends to underestimate the performance of filters with high DHC. Additionally, we proposed a simple method to predict the filter's operating pressure drop, using particle concentration data from weather report. This allows for convenient assessment of the fresh air system's operating status, offering potential integration into a user-friendly mobile application or computer software. These findings contribute innovative ideas for enhancing the intelligent and energy-efficient operation of fresh air systems.

Structure of the oral tentacles of early ontogeny stage in brachiopod Hemithiris psittacea (Rhynchonelliformea, Rhynchonellida).

Brachiopods have the most complex lophophore in comparison with other lophophorates, i.e., phoronids and bryozoans. However, at early ontogenetic stages, brachiopods have a lophophore of simple morphology, which consists of the oral tentacles. Data on the ultrastructure of the oral tentacles is mostly missing. Nonetheless, it has recently been suggested that the structure of oral tentacles is ancestral for all lophophorates in general, and for brachiopods in particular. The fine structure of the oral tentacles in the brachiopod Hemithiris psittacea is studied using light microscopy, transmission and scanning electron microscopy, cytochemistry and confocal laser scanning microscopy. The oral tentacles have a round shape in transverse section, and four ciliary zones, i.e., one frontal, two lateral, and one abfrontal. Latero-frontal sensory cells occur among the frontal epithelium. Four basiepithelial nerves in the ciliary epithelium are colocalized with ciliary zones. Lophophores of simple morphology in phoronids and brachiopods are characterized by non-specified round forms of tentacles. In phoronids and bryozoans, tentacles have additional latero-frontal ciliary zones that function as a sieve during filtration. In most brachiopods, lateral cilia are involved in the capture of food particles, whereas latero-frontal cells are retained in the frontal zone as sensory elements. The oral tentacles of H. psittacea contain a coelomic canal and have distinct frontal and abfrontal longitudinal muscles, which are separated from each other by peritoneal cells. A similar structure of tentacle muscles occurs in all bryozoans, whereas in phoronids, the frontal and abfrontal tentacle muscles are not separated by peritoneal cells. We suggest that the lophophorates' ancestor had tentacles, which were similar to the tentacles of some phoronids with lophophore of simple morphology. We also assume that the structure of the oral tentacles is ancestral for all brachiopods and the specialization of brachiopod tentacles correlates with the appearance of the double row of tentacles.

Development of Cellulose Air Filters for Capturing Fine and Ultrafine Particles through the Valorization of Banana Cultivation Biomass Waste

Outdoor and indoor atmospheric pollution is one of the major problems that humanity continues to face. As a mitigation pathway, numerous technologies have been developed for air purification, including the use of fibrous filters. In this study, the particle capture efficiencies and pressure drops of air filters manufactured with cellulose pulp extracted from banana pseudostems were studied across three particle size ranges (PM10, PM2.5, and PM1). Two pretreatments were applied, alkaline with soda-antraquinone (alkali-treated pulp) and a subsequent bleaching process (bleached pulp), and four manufacturing processes were tested: crushing, freeze-drying, vacuum filtration, and pressing. In addition, a study varying filter grammage (70, 100, and 160 g·m−2) and pressing pressures (2, 4, 6, and 8 t) was also performed. After conducting these particle tests, the filter manufactured with bleached pulp, having a grammage of 160 g·m−2 and pressed at 4 t, was deemed the optimal individual solution. It demonstrated high particle retention efficiencies across all particle size ranges (with values exceeding 80%), a moderate pressure drop below 1000 Pa, and high thermal stability (degradation above 220 °C). However, combining freeze-drying and two-ton pressing processes yielded improved results (83% for the smallest particles and 89% for others) with approximately half the pressure drop. Based on these results, this study stands as a noteworthy contribution to waste valorization and the advancement of environmentally friendly materials for particle air filters. This is achieved through the adoption of simple and cost-effective technology, coupled with the utilization of 100% natural agricultural waste as the primary manufacturing material.

Multifunctional metalens optical tweezers for optical information recognition.

Traditional optical information recognition (OIR), particle capture and manipulation require many optical devices or mechanical moving system components to achieve a specific function, which is difficult to achieve integration. This paper proposes a new method to realize these functions by using multi-focus metalens combining spectrum and polarization selection. The design incorporates three spectral bands, namely 500 nm, 580 nm, and 660 nm, within the visible light range. Additionally, it utilizes either left-handed or right-handed circularly polarized (LCP/RCP) light, resulting in six distinct focus focusing effects on a single focal plane. By analyzing the normalized light intensity (NLI) at the corresponding focus position, the OIR of any wavelength and polarization detection in the design can be realized, and the particle capture at different focusing positions can be realized. Our work can provide a new idea for the high integration of on-chip light recognition and operation and inspire the design of a highly integrated optical system with a smaller size and more substantial function.

Colloidal Engineering of Microplastic Capture with Biodegradable Soft Dendritic "Microcleaners".

The introduction of colloidal principles that enable efficient microplastic collection from aquatic environments is a goal of great environmental importance. Here, we present a novel method of microplastic (MP) collection using biodegradable hydrogel soft dendritic colloids (hSDCs). These dendritic colloids have abundant nanofibrils and a large surface area, which provide an abundance of interfacial interactions and excellent networking capabilities, allowing for the capture of plastic particles and other contaminants. Here, we show how the polymer composition and morphology of the hSDCs can impact the capture of microplastics modeled by latex microbeads. Additionally, we use colloidal DLVO theory to interpret the capture efficiencies of microbeads of different sizes and surface functional groups. The results demonstrate the microplastic remediation efficiency of hydrogel dendricolloids and highlight the primary factors involved in the microbead interactions and adsorption. On a practical level, the results show that the development of environmentally benign microcleaners based on naturally sourced materials could present a sustainable solution for microplastic cleanup.

Contextual existence of an optimum through-plane orientation and aspect ratio of a fiber-segment in fibrous air filters

Fibrous air filters have emerged extensively as a remedial indoor solution to address severe air pollution. To understand the complexities involved in variation of their performance with respect to their fiber anisotropy, a fundamental numerical study is undertaken to investigate the capture of inertia-dominated airborne particles by a fiber-segment at different through-plane orientations with respect to airflow direction. An in-house MATLAB code has been developed using the lattice Boltzmann method to model the airflow across fiber-segment, coupled with the Lagrangian approach to model the motion of particles as well as their interactions with the fiber-segment. The filtration performance parameters, viz., capture efficiency, pressure drop, and quality factor, have been evaluated at different through-plane orientations of the fiber-segment for its various segmental aspect ratios and different Stokes numbers. It is found that as the fiber-segment is turned from a parallel to orthogonal orientation with respect to airflow direction, the capture efficiency and pressure drop exhibit either a monotonic rise or broadly an increasing–decreasing kind of trend with an intermediate maximum, depending on the segmental aspect ratio of fiber and the Stokes number. Also, both these parameters are observed to decrease as the segmental aspect ratio of fiber is increased. Furthermore, an optimum through-plane orientation as well as an optimum segmental aspect ratio of the fiber-segment are found to exist for which the overall filtration performance is highest. The indicative optimum through-plane orientation of the fiber-segment is found to be a function of its segmental aspect ratio but not the Stokes number.

Optimization of filter structures by evolutionary strategies

The increasing pressure drop of filter media during the capture of solid particles is directly correlated to the energy consumption. It is largely based on the microstructure of the media, especially with regard to the selected porosity gradient. The development of new filter media optimized for separation efficiency and energy consumption is based mainly on experimental work. The use of evolutionary algorithms inspired by nature is of particular interest for the optimization of filter media, as a large number of non-linear influencing factors can be processed. However, a large number of simulations is required for successful application in order to reproduce the natural process of mutation and individual selection. Most numerical simulations of filtration properties are limited due to the high computing power required, making them unsuitable in this context. Therefore, a 1D simulation with low computing power requirements was used in this paper to simulate the loading of a filter medium with particles. This approach enabled the rapid calculation of the loading of different filter media structures, and was coupled with an evolutionary algorithm with the aim of optimizing the porosity gradient. The algorithm was tested on different particle size distributions, which represented different operating conditions. The porosity gradients of the optimized filters was in the form of an inverse square function, leading to a much more homogenous, microscopic loading with particles. Due to the significantly improved utilization of the filter depth compared to a reference medium, a much slower increase in pressure difference could be obtained with a similar filtration efficiency, resulting in increased quality factors of 30% and higher. The optimization of an operating point took about 24 hours on a standard desktop PC and could be extended to other structural parameters of the filter medium apart from the porosity gradient. This shows the potential for a broad application in the selection and optimization of filter media.

Modeling the Process of Pollutant Spread in the Atmosphere with Account for the Capture of Particles by Vegetation Elements

Modeling the Process of Pollutant Spread in the Atmosphere with Account for the Capture of Particles by Vegetation Elements