scholarly journals Multi-Scale Microstructure Investigation for a PM2.5 Air-Filter Efficiency Study of Non-Woven Polypropylene

2019 ◽  
Vol 3 (4) ◽  
pp. 20 ◽  
Author(s):  
Tu-Ngoc Lam ◽  
Chen-Hsien Wu ◽  
Sheng-Hsiu Huang ◽  
Wen-Ching Ko ◽  
Yu-Lih Huang ◽  
...  
Keyword(s):  
Particle Size ◽  
Collection Efficiency ◽  
Three Dimensional ◽  
Fiber Surface ◽  
Filter Material ◽  
Particle Size Range ◽  
Air Filter ◽  
Geometrical Properties ◽  
Multi Scale ◽  
Face Velocity

A N95 face-piece respirator and a 3M air filter composed of non-woven polypropylene filter material were investigated for their multi-scale microstructure and resulting filtration performance. Filtration mechanisms of each system are found and quantified. Both media showed a gradually decrease of the most penetrating particle size with respect to an increase in face velocity or surface charge density. Increasing the face velocity and porosity dramatically degraded the collection efficiency in the 3M filter rather than in the N95 system. We exploited three-dimensional X-ray tomography to characterize the morphological and geometrical properties of the fiber arrangement and deposition of aerosol on the fiber surface. Tuning the most predominant material parameters to achieve a precedence in lower pressure drop or higher collection efficiency in a specifically captured particle size range is of great requisite to a peculiar application of the filter media.

scholarly journals Measurement report: Particle-size-dependent fluorescence properties of water-soluble organic compounds (WSOCs) and their atmospheric implications for the aging of WSOCs

2022 ◽  
Vol 22 (1) ◽  
pp. 465-479
Author(s):  
Juanjuan Qin ◽  
Jihua Tan ◽  
Xueming Zhou ◽  
Yanrong Yang ◽  
Yuanyuan Qin ◽  
...  
Keyword(s):  
Particle Size ◽  
Organic Compounds ◽  
Fine Particles ◽  
Size Range ◽  
Stokes Shift ◽  
Three Dimensional ◽  
Water Soluble ◽  
Particle Size Range ◽  
Humification Degree ◽  
Transformation Processes

Abstract. Water-soluble organic compounds (WSOCs) play important roles in atmospheric particle formation, migration, and transformation processes. Size-segregated atmospheric particles were collected in a rural area of Beijing. Three-dimensional fluorescence spectroscopy was used to investigate the optical properties of WSOCs as a means of inferring information about their atmospheric sources. Sophisticated analysis on fluorescence data was performed to characteristically estimate the connections among particles of different sizes. WSOC concentrations and the average fluorescence intensity (AFI) showed a monomodal distribution in winter and a bimodal distribution in summer, with the dominant mode in the 0.26–0.44 µm size range in both seasons. The excitation–emission matrix (EEM) spectra of WSOCs varied with particle size, likely due to changing sources and/or the chemical transformation of organics. Size distributions of the fluorescence regional integration (regions III and V) and humification index (HIX) indicate that the humification degree or aromaticity of WSOCs was the highest in the particle size range of 0.26–0.44 µm. The Stokes shift (SS) and the harmonic mean of the excitation and emission wavelengths (WH) reflected that π-conjugated systems were high in the same particle size range. The parallel factor analysis (PARAFAC) results showed that humic-like substances were abundant in fine particles (< 1 µm) and peaked at 0.26–0.44 µm. All evidence supported the fact that the humification degree of WSOCs increased with particle size in the submicron mode (< 0.44 µm) and then decreased gradually with particle size, which implied that the condensation of organics occurred in submicron particles, resulting in the highest degree of humification in the particle size range of 0.26–0.44 µm rather than in the < 0.26 µm range. Synthetically analyzing three-dimensional fluorescence data could efficiently reveal the secondary transformation processes of WSOCs.

scholarly journals A Sustainable Recycling Alternative: Electrospun PET-Membranes for Air Nanofiltration

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1166
Author(s):  
Daniela P. F. Bonfim ◽  
Fabiana G. S. Cruz ◽  
Rosario E. S. Bretas ◽  
Vádila G. Guerra ◽  
Mônica Lopes Aguiar
Keyword(s):  
Indoor Air ◽  
Collection Efficiency ◽  
Mechanical Resistance ◽  
High Porosity ◽  
Air Filter ◽  
Aerosol Nanoparticles ◽  
Plastic Materials ◽  
Electrospun Membranes ◽  
Clean Air ◽  
Face Velocity

Currently, the inappropriate disposal of plastic materials, such as polyethylene terephthalate (PET) wastes, is a major environmental problem since it can cause serious damage to the environment and contribute to the proliferation of pathogenic microorganisms. To reduce this accumulation, PET-type bottles have been recycled, and also explored in other applications such as the development of membranes. Thus, this research aims to develop electrospun microfiber membranes from PET wastes and evaluate their use as an air filter media. The solution concentrations varied from 20 to 12% wt% of PET wastes, which caused a reduction of the average fiber diameter by 60% (from 3.25 µm to 1.27 µm). The electrospun filter membranes showed high mechanical resistance (4 MPa), adequate permeability (4.4 × 10−8 m2), high porosity (96%), and provided a high collection efficiency (about 100%) and low-pressure drop (212 Pa, whose face velocity was 4.8 cm/s) for the removal of viable aerosol nanoparticles. It can include bacteria, fungi, and also viruses, mainly SARS-CoV-2 (about 100 nm). Therefore, the developed electrospun membranes can be applied as indoor air filters, where extremely clean air is needed (e.g., hospitals, clean zones of pharmaceutical and food industry, aircraft, among others).

Modeling Flow Across a Race Car Air Filter

2006 ◽  
Author(s):  
Robert Binns ◽  
Kim A. Shollenberger
Keyword(s):  
Boundary Condition ◽  
Pressure Drop ◽  
Numerical Simulations ◽  
Three Dimensional ◽  
Filter Material ◽  
Fuel Mixture ◽  
Air Filter ◽  
Pressure Drops ◽  
Curve Fit ◽  
Visualization Techniques

Air entering a NASCAR stock car travels through an air filter enclosed in an “airbox” before being mixed with fuel. To maximize the mass of air/fuel mixture delivered to the cylinders, it is desired to minimize airflow restrictions. This paper presents a preliminary model to predict pressure drop and airflow across an air filter in a simplified geometry. The model includes experimental measurements and numerical simulations using a three-dimensional finite-volume package. The simplified geometry is a 1.52-m long flow channel with 12.7 cm by 7.97 cm cross-section. Measurements of pressure drop versus air velocity were made for separate and combined elements of the filter. A curve fit to the data is used to calculate coefficients for a porous-jump boundary condition used to model flow through porous media. Numerical simulations were run using this model for each filter element in the simplified geometry to verify that measured and calculated pressure drops agreed. Finally, flow visualization techniques were used to reveal streaklines in the flow. Good agreement was found between calculated streamlines and experimental observations. Thus, the porous jump boundary condition is a valid model for the filter material. Future work will include three-dimensional, transient numerical simulations of airflow within the airbox.

scholarly journals Three-Dimensional Imaging Lidar for Characterizing Particle Fields and Organisms in the Mesopelagic Zone

2020 ◽  
Vol 7 ◽  
Author(s):  
Trevor McKenzie ◽  
Michael Twardowski ◽  
Nathan Briggs ◽  
Aditya R. Nayak ◽  
Kevin M. Boswell ◽  
...  
Keyword(s):  
Time Series ◽  
Particle Size ◽  
Size Range ◽  
Three Dimensional ◽  
Vital Role ◽  
Inversion Method ◽  
Particle Size Range ◽  
Particle Field ◽  
Mesopelagic Zone ◽  
Order Of Magnitude

The ocean’s mesopelagic zone is largely uncharacterized despite its vital role in sustaining ocean ecosystems. The composition, cycling, and fate of particle fields in the mesopelagic lacks an integrative multi-scale understanding of organism migration patterns, distribution, and diversity. This problem is addressed by combining complementary technologies with overlapping size spectra, including profiler mounted optical scattering sensors, profiler, and ship mounted acoustic devices, and a custom Unobtrusive Multi-Static Lidar Imager (UMSLI). This unique sensor suite can observe distributions of particles including organisms over a six order of magnitude dynamic size range, from microns to meters. Overlapping size ranges between different methods allows for cross-validation. This work focuses on the lidar imaging measurements and optical backscattering and attenuation, covering a combined particle size range of 0.1 mm to several cm. Particles at the small end of this range are sized using an existing backscattering time series inversion method after Briggs et al. (2013). Larger particles are resolved with UMSLI over an expanding volume using three-dimensional photo-realistic laser serial imaging. UMSLI’s image rectifying ability over time allows for derivation of particle concentration, size, and spatial distribution. Technical details on the development and post-processing methods for the novel UMSLI system are provided. Image resolved particle size distributions (PSDs) revealed a size shift from smaller to larger particles (&gt;0.5 mm) as indicated by flatter slopes from dawn (slope = 2.6) to dusk (slope = 3.0). PSD trends are supported by an optical backscatter and transmissometer time series inversion analysis. Size shifts in the particle field are largely attributed to aggregation effects. Images support evidence of temporal variation between dusk and dawn stations through statistical analysis of particle concentrations for particle sizes 0.50–5.41 mm. Spatial analysis of the particle field revealed a dominantly uniform distributed marine snow background. The importance and potential of integrated approaches to studying particle and organism dynamics in ocean environments are discussed.

scholarly journals Design of a mono-disperse aerosol generator for efficiency testing of HEPA filter

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Guoxiu Qin ◽  
Liangliang Pan ◽  
Youning Xu ◽  
Fan Li ◽  
Yi Liang
Keyword(s):  
Particle Size ◽  
High Efficiency ◽  
Condensation Nucleus ◽  
Performance Tests ◽  
Particle Size Range ◽  
Air Filter ◽  
Aerosol Generation ◽  
Aerosol Generator ◽  
Aerosol Performance ◽  
And Performance

AbstractA set of mono-disperse aerosol generator was designed to meet the requirement of efficiency testing for high efficiency particle air filter. The aerosol generation tests and performance tests were conducted by using evaporation–condensation method, with NaCl solutions at different concentrations as the condensation nucleus and respectively using the DEHS, DOP, PAO–4 as reagents. The results show that three reagents can generate mono-disperse aerosol particles by strictly controlling various parameters which affects the aerosol performance, where the particle size range is 0.33–0.36 μm for DEHS, 0.35–0.37 μm for DOP and 0.34–0.36 μm for PAO–4 and the concentrations of the aerosols lager than 106 cm–3. The particle size characteristics and concentrations generated through such method basically conform to the requirements of efficiency testing for high efficiency particle air filter.

381. Sampling Efficiencies of Three Personal Aerosol Samplers within and Beyond the Inhalable Particle Size Range

2001 ◽  
Author(s):  
V. Aizenberg ◽  
P. Baron ◽  
K. Choe ◽  
S. Grinshpun ◽  
K. Willeke
Keyword(s):  
Particle Size ◽  
Size Range ◽  
Particle Size Range

Three-dimensional Reconstruction of Microscopic Image Based on Multi-ST Algorithm

2020 ◽  
Vol 64 (2) ◽  
pp. 20506-1-20506-7
Author(s):  
Min Zhu ◽  
Rongfu Zhang ◽  
Pei Ma ◽  
Xuedian Zhang ◽  
Qi Guo
Keyword(s):  
3D Reconstruction ◽  
Three Dimensional ◽  
Scale Model ◽  
Microscopic Image ◽  
Multi Scale ◽  
Gaussian Pyramid ◽  
Cost Aggregation ◽  
Dimensional Reconstruction ◽  
Image Pairs ◽  
Accurate Matching

Abstract Three-dimensional (3D) reconstruction is extensively used in microscopic applications. Reducing excessive error points and achieving accurate matching of weak texture regions have been the classical challenges for 3D microscopic vision. A Multi-ST algorithm was proposed to improve matching accuracy. The process is performed in two main stages: scaled microscopic images and regularized cost aggregation. First, microscopic image pairs with different scales were extracted according to the Gaussian pyramid criterion. Second, a novel cost aggregation approach based on the regularized multi-scale model was implemented into all scales to obtain the final cost. To evaluate the performances of the proposed Multi-ST algorithm and compare different algorithms, seven groups of images from the Middlebury dataset and four groups of experimental images obtained by a binocular microscopic system were analyzed. Disparity maps and reconstruction maps generated by the proposed approach contained more information and fewer outliers or artifacts. Furthermore, 3D reconstruction of the plug gauges using the Multi-ST algorithm showed that the error was less than 0.025 mm.

scholarly journals Hemp (Cannabis sativa L.) Seed Protein–EGCG Conjugates: Covalent Bonding and Functional Research

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1618
Author(s):  
Xin-Hui Pang ◽  
Yang Yang ◽  
Xin Bian ◽  
Bing Wang ◽  
Li-Kun Ren ◽  
...  
Keyword(s):  
Particle Size ◽  
Fluorescence Spectroscopy ◽  
Cannabis Sativa ◽  
Three Dimensional ◽  
Epigallocatechin Gallate ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Particle Size Data ◽  
Covalently Bonded ◽  
Covalently Linked

In order to make HPI have a wide application prospect in the food industry, we used EGCG to modify HPI. In this study, we prepared different concentrations (1, 2, 3, 4, and 5 mM) of (−)-epigallocatechin gallate (EGCG) covalently linked to HPI and use methods such as particle size analysis, circular dichroism (CD), and three-dimensional fluorescence spectroscopy to study the changes in the structure and functional properties of HPI after being covalently combined with EGCG. The particle size data indicated that the covalent HPI-EGCG complex was larger than native HPI, and the particle size was mainly distributed at about 200 μm. CD and three-dimensional fluorescence spectroscopy analyses showed that the conformation of the protein was changed by conjugation with EGCG. The β-sheet content decreased from 82.79% to 66.67% after EGCG bound to the protein, and the hydrophobic groups inside the protein were exposed, which increased the hydrophobicity of the protein and changed its conformation. After HPI and 1 mM of EGCG were covalently bonded, the solubility and emulsifying properties of the covalent complex were improved compared with native HPI. These results indicated that HPI-EGCG conjugates can be added in some foods.

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