Μm Particulates Research Articles

Development of anti-corrosion, structural, and optoelectronic potential of Capsicum annuum-Doped AA6063 alloy for marine applications

The study explores the potential of incorporating pepper waste as a reinforcement material in aluminium AA6063 composites, with focussing on the morphological, mechanical, electrochemical, and optoelectric properties. Pepper wastes, including stalks and seeds, were carbonised, pulverized, and sieved to yield 75 μm particulates. These were mixed with molten AA6063 alloy via stir casting, with the pepper content ranging from 0% to 25% by weight. The composites were characterised using hardness testing, electrochemical evaluation, optoelectrical analysis, and morphological analysis. Hardness tests revealed that the 25% pepper-reinforced sample exhibited the highest hardness value of 37 HRB, a 31.7% increase over the control sample. Electrochemical evaluations showed significant improvements in corrosion resistance, with the corrosion potential (Ecorr) of the 25% pepper-reinforced sample reducing to −0.59 V and the corrosion rate decreasing to 7.69 mm/yr. Optoelectrical testing indicated enhanced conductivity in samples with higher pepper content, with the 25% reinforcement achieving a conductivity of 0.1979 (Ωm)⁻1. Morphological tests, such as SEM and XRD, revealed the uniform distribution of pepper particles and the occurrence of several phases that contribute to the composite's improved properties.

Development of Multi-Walled Carbon Nanotube-Integrated Recycled Polyethylene Terephthalate Electrospun Antibacterial Face Mask

In this study, electrospun nanofiber membranes were successfully fabricated by modifying recycled polyethylene terephthalate (r-PET) with multi-walled carbon nanotubes (MWCNTs) for face mask applications. The recycling of PET bottles ensures effective waste management, while the electrospinning process facilitates the creation of delicate nano-range fibers. The inclusion of MWCNTs aimed to assess the antibacterial activity of the resulting nanomembranes. The fabricated samples underwent comprehensive characterization, including scanning electron microscopy (SEM), ultimate tensile testing, particulate filtration efficiency (PFE) testing, Fourier transform infrared spectroscopy (FTIR), and antibacterial sensitivity assays, revealing significant findings. MWCNTs incorporation led to minor bead formation in the membranes, with fiber diameters ranging from 446 to 862 nm. However, MWCNTs resulted in reduced stiffness and tensile properties due to the disruption of polymer chain alignment. The nanofiber membranes demonstrated effective filtration of 0.3 µm particulates, achieving filtration rates between 96 to 97%Functional group analysis confirmed the presence of both r-PET and MWCNTs in the composites. Although the r-PET/MWCNTs 12 kV membrane lacked an antibacterial zone of inhibition, it exhibited reductions of 28.64% for S. aureus and 31.9% for E. coli. These results collectively underscore the potential of r-PET/MWCNTs samples as an alternative nanofibrous membrane material for face masks. J. of Sci. and Tech. Res. 5(1): 63-74, 2023

Cellulose nanofiber aerogels modified with titanium dioxide nanoparticles as high-performance nanofiltration materials

Air pollution is a major environmental and public health issue. Each year, large amounts of particulate matter (PM) and other harmful pollutants are released into the atmosphere. Conventional polymer nanofiber filters lack the functionality to capture ultrafine PM. As a sustainable alternative, this work developed titanium dioxide (TiO2) nanoparticle surface-modified cellulose nanofiber (CNF) aerogels for PM2.5 filtration. CNFs were extracted via mechanical disintegration to diameters below 100 nm. The nanofibers were functionalized with 1.0–2.5 wt% TiO2 nanoparticles using citric acid cross-linking. Cylindrical aerogels were fabricated by freezing and lyophilizing aqueous suspensions. Structural, morphological, thermal, and mechanical properties were characterized. TiO2 modification increased density (11.8–19.7 mg/cm3), specific surface area (287–370 m2/g), and Young's modulus (33.5–125.5 kPa) but decreased porosity (99.6 %–97.7 %), pore size (20.2–15.6 nm) and thermal stability compared to unmodified cellulose aerogels. At 2.5 wt% loading, the optimized aerogels achieved 100 % absorption of 0.1–5 μm particulates owing to reduced pore size. Despite enhanced filtration capabilities, the modified CNF aerogels retained inherent biodegradability, degrading over 70 % within one month of soil burial. This pioneering research establishes TiO2 functionalized CNF aerogels as promising sustainable alternatives to traditional petroleum-based air filters, representing an innovative approach to creating next-generation nanofiltration materials capable of effectively capturing fine and ultrafine particulate matter pollutants.

Differences in Performance and Conductivity Persistence of New Reduced Graphene Oxide Air Filter Materials before and after Eliminating Static Electricity.

Improving the filtration efficiency of air filter materials is an ongoing research goal. This study conducted in-depth research on a new reduced graphene oxide air filter material, and the differences in its performance and conductivity durability before and after eliminating static electricity were tested and analyzed. The results showed that the filtration efficiency of the reduced graphene oxide air filter material significantly decreased after eliminating static electricity. The maximum decrease in filtration efficiency was observed at a filtration velocity of 0.8 m/s, with PM10 > PM1.0 > PM2.5. In this case, the filtration efficiency decreased by 11.8%, 7.98%, and 7.17%, respectively. The maximum difference in filtration efficiency of 0.29 μm particulates was about 12.7%. Eliminating static electricity slightly increased the resistance (2.5~15.5 Pa). In addition, the new reduced graphene oxide air filter material exhibited good conductivity and stability after continuous testing. This study provides data support for the application of subsequent electrification sterilization, reference values for multi-angle applications, and the development of new composite air filter materials.

A novel semi-dry method for rapidly synthesis ZnO nanorods on SiO2@PTFE nanofiber membrane for efficient air cleaning

Particulate matter including dust and airborne microorganisms has severe effect on indoor air quality and thus be injurious to human health. In this research, inspired by corals, a tentacle-like ZnO nanorods (NRs) decorated SiO 2 @PTFE nanofibers was prepared by a novel semi-dry method combining rapid dipping and solid-phase drying process. The controllable growth of ZnO nanostructures can be achieved by adjusting the numbers of dipping cycles. It may be the most simple and effective way to prepare sufficiently crystallized ZnO nanostructures at relatively facile conditions without high temperature calcination and any pressure vessels. The obtained ZnO NRs-SiO 2 @PTFE nanofiber membrane (NFM) with a hierarchical fibrous structure possesses uniform pore structure (average pore size 0.92 μm), high gas permeance (626.4 m 3 ∙m −2 ∙h −1 ∙kPa −1 ), and a superior filtration property (99.997% for 0.3 μm particulates). Moreover, the active ZnO with enhanced specific surface also exhibits good antibacterial property with sterilization rate of 99.67% and 99.93% for E. coli and B. subtilis , respectively. The ZnO growth mechanism and air cleaning principle including dust filtration and bacteria sterilization were analyzed by the corresponding experiments. This work provides a new insight into the dual-function air cleaning membrane preparation via a mild and simple reaction conditions, energy efficient and environment friendly strategy. • A facile semi-dry method for preparing ZnO NRs decorated SiO 2 @PTFE NFMs. • The corals tentacle-like ZnO NRs help to capture and deactivate microorganisms. • The membrane exhibits excellent filtration property with low pressure drop. • The method is energy saving and environment friendly for scale up application.

Effect of a Δ9-tetrahydrocannabinol (THC)/cannabidiol (CBD) formulation on cell monolayer viability and mitochondria integrity: Significance of the drug carrier/delivery system

Background: The increasing availability and abuse of recreational and medical cannabis has been associated with patients presenting with cyclical nausea, vomiting, intestinal cramps, and other manifestations, referred to as cannabinoid hyperemesis syndrome. An exact etiologic mechanism, especially on the cellular level, remains unclear. Continual studies are needed to address the effect of cannabinoid activity specifically addressing that which occurs in the gastrointestinal tract. Methods: Cannabinoids in general, are immiscible in water-based cell culture media. Homogenization was performed to bring a THC/CBD formulation into a workable state for in vitro testing. The human colon adenocarcinoma (HT-29) epithelia cell line was used throughout this study. Mitochondrial cytotoxicity testing was performed using a fluorescein conjugated monoclonal antibody to the organelle’s outer membrane protein. Mitochondrial morphology was performed by transmission electron microscopy utilizing a commercially available cannabidiol product. Cell cultures, incubated with 50 to 125 µg/ml of a THC/CBD formulation for 72-h, were viewed daily for the appearance of a monolayer degeneration or a cytopathogenic effect. Results: Cell monolayers treated with non-homogenized THC/CBD in phosphate-buffered saline or utilizing DMSO as analyte diluents, proved unremarkable. However, homogenization of the cannabinoid formulation at > 50 µg/ml affected a loss of monolayer confluency and mitochondrial membrane surface protein. Treatment of monolayers with CBD affected a loss of mitochondrial morphology as observed by an absence of organelle cristae and matrix structure. Mitochondrial loss of surface protein integrity occurred prior to monolayer degeneration. Conclusion: A cytotoxic effect was realized in colon cell cultures following treatment with a cannabinoid liquid tincture formulation at concentrations > 50 µg/ml. The degenerative effect by the cannabinoid formulation was directed initially to a marked loss of mitochondrial morphology and loss of [organelle] surface integrity, followed by a monolayer degeneration. Critically, the immiscible THC/CBD analyte mandated a size distribution of lipid globules to single digit of smaller µM particulates. Globule reduction was achieved by high speed homogenization. Additional studies in the animal model are needed to further address our findings in the search for an etiology to cannabinoid hyperemesis syndrome.

Real-time sampling of particulate matter smaller than 2.5 μm from Amazon forest biomass combustion

Particle size distribution from forest biomass combustion is an important parameter as it affects air quality, global climate and human health. There have been several studies that relate emission of 2.5–10 μm particulates and their effects on human health. The objective of this study was to sample particulates smaller than 2.5 μm from Amazon forest biomass burning in laboratory and field experiments. Sampling was carried out using three instruments: two DataRAM 4 (model DR 4000) and a Cascade Impactor. Isokinetic probes were used for sampling in the stacks, and an omnidirectional instrument was used for field sampling. The field experiment was conducted in a 4 ha Amazon forest test site in the state of Acre, in Brazil. Ignition, flaming and smoldering combustion phases were analyzed. Results were obtained in terms of particle size distribution and concentration. Comparison of laboratory and field experiments showed that particle size distributions were similar in both cases. Particle sizes obtained in the laboratory ranged from 0.05 to 0.8 μm; in the field experiment, sizes varied from 0.03 to 0.3 μm. Average concentrations in the laboratory and in the field were 185 mg m−3 and 350 mg m−3, respectively. It is important to emphasize that those results were obtained throughout the burning process and the diameters sampled were smaller than 2.5 μm.

Seasonal export fluxes of size-fractionated particulate derived from polonium-210: A case study in Xiamen Bay

Size-fractionated 210Po and 210Pb, in the size fractions >0.4 μm, >2 μm and >10 μm, were examined to determine the seasonal variability of particulate fluxes in Xiamen Bay. Good correlations between 210Po and particulate organic carbon (POC) or non-Particulate Organic Matter (nPOM) suggested that 210Po can be used to trace the export fluxes of POC and nPOM. Both steady-state (SS) model and nSS model were used to evaluate fluxes of size-fractionated 210Po, results showed that nSS model was better than the SS model in coastal areas. Based on the nSS model, size-fractionated POC fluxes decreased with increasing particle size. For the particle size studied, maximum POC fluxes occurred in autumn, followed by spring, winter, and summer. Fluxes of nPOM were an order of magnitude higher than the corresponding size-fractionated POC fluxes. Differences between size-fractionated nPOM fluxes indicated that hydrodynamic conditions were the main factor regulating transportation of particulate out of the inner Bay. In winter most particulates, including >10 μm particles, were transported under the strongest hydrodynamic conditions. In contrast, only a fraction of the <2 μm particulates were transported from the inner Bay in spring. This study suggested that 210Po is a powerful tracer of seasonal particulate export in coastal seas.

Study on quality assurance system of grade 3 laminar operation room

Objective To explore the features of the cleanliness change with time during the use of laminar operating rooms in order to establish reliable quality assurance system. Methods Two grade 3 lami-nar operation rooms were chosen to be tested after one and a half year and two and a half years, laser counter was used to detect the static particulates after cleaning for 30 minutes and 45 minutes. Results After the laminar operation room was used for one and a half years the amount of 0.5 μm particulates in indoor air was less than 350 per liter, and after two and a half years it's above 350 per liter after cleaning for 30 minutes, an obvious difference than the previous one. The anaount of 1 μm and 2 pan particulates also increase obviously, but ff cleaning for 45 minutes the amount of 0.5 μm particulates in indoor air will fulfill the qualification. Al-though the amount of 0.5 μm, 1 pan and 2 μm particulates after 2 years using was higher than the one and a half yesrs'using after cleaning for 45 minutes, but the difference had no statistic meaning. Condusions The elesnliness of laminar operation rooms will drop as time prolonged, Amount of particulates in indoor air will in-crease too but the cleanliness can be ensured by extending cleaning time. After the quality assurance sys-tem was established the amount of smile particulates is still within the standard level Key words: laminar operation room; Quality; Mmanagement;

Bioglass thin films for biomimetic implants

Pulsed laser deposition (PLD) method was used to obtain bioglass (BG) thin film coatings on titanium substrates. An UV excimer laser KrF* ( λ = 248 nm, τ = 25 ns) was used for the multi-pulse irradiation of the BG targets with 57 or 61 wt.% SiO 2 content (and Na 2O–K 2O–CaO–MgO–P 2O 5 oxides). The depositions were performed in oxygen atmosphere at 13 Pa and for substrates temperature of 400 °C. The PLD films displayed typical BG of 2–5 μm particulates nucleated on the film surface or embedded in. The PLD films stoichiometry was found to be the same as the targets. XRD spectra have shown, the glass coatings obtained, had an amorphous structure. One set of samples, deposited in the same conditions, were dipped in simulated body fluids (SBFs) and subsequently extracted one by one after several time intervals 1, 3, 7, 14 and 21 days. After washing in deionized water and drying, the surface morphology of the samples and theirs composition were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), IR spectroscopy (FTIR) and energy dispersive X-ray analysis (EDX). After 3–7 days the Si content substantially decreases in the coatings and PO 4 3− maxima start to increase in FTIR spectra. The XRD spectra also confirm this evolution. After 14–21 days the XRD peaks show a crystallized fraction of the carbonated hydroxyapatite (HAP). The SEM micrographs show also significant changes of the films surface morphology. The coalescence of the BG droplets can be seen. The dissolution and growth processes could be assigned to the ionic exchange between BG and SBFs.

Quantification of pollutants emitted from very large wildland fires in Southern California, USA

This study investigates the efficacy of the first order fire effects model (FOFEM) implemented in a geographic information system for wildland fire emissions estimation. The objective of the study was to quantify the source and composition of smoke and emissions from wildland fires that burned 235,267 ha in Southern California, USA, in October 2003. From inputs of vegetation, fuel model data, weather condition data, and fire perimeters, the model produces estimates of ten pollutant species (10 and 2.5 μm particulates, carbon dioxide, carbon monoxide, methane, non-methane hydrocarbons, ammonia, nitrous oxide, oxides of nitrogen, sulfur dioxide) from ten fuel categories (duff, litter, woody debris in three size classes, herbs, shrubs, tree regeneration, live branch-wood and live foliage). From the Southern California fires, the model estimated over 5 million metric tons (megagrams) of total pollutant emissions over several days. These emissions include over 457,000 tons of carbon monoxide, over 6 million tons (approximately 6 Tg) of carbon dioxide, and over 46,000 tons of particulates. Fuels that contributed the most mass to the fire emissions were predominantly shrubs and duff.

Measurement of labile Cu, Pb and their complexation capacity in Yueqing Bay in Zhejiang Province, China

The complexation capacity of Cu and Pb and their labile and organic contents were determined separately for surface seawater samples from Yueqing Bay. The samples were prepared using Nuclepore filtration method yielding 0.2μm particles. The complexation capacity of Pb with <0.2μm particulates was smaller than that with 0.2–1.0μm particulates, and averaged 11.5 and 23.0nmol/L respectively. The results suggested that colloidal particles were responsible for the distribution and concentration of Pb in seawater.

The role of nitric oxide in the particulate matter (PM2.5)-induced NFκB activation in lung epithelial cells

NFκB is one of key transcription factors that are involved in the inflammatory responses to the particulate matter (PM) in the lungs. In order to further understand the molecular mechanism, the effects of antioxidants and an inducible nitric oxide synthase (iNOS) inhibitor on PM-induced NFκB activation were examined in A549 lung epithelial cells. NFκB activation by 2.5 μm particulates (PM2.5) was evident from the degradation of an NFκB inhibitory protein, IκBα, and a luciferase reporter assay for NFκB activity. In these experiments, a pre-treatment of the cells with antioxidants N-acetyl- l-cysteine (NAC) and dimethylthiourea (DMTU) or an iNOS inhibitor l- N 6-1-iminoethyl-lysine (L-NIL) clearly inhibited the NFκB activation by PM2.5. The inhibitory effect of L-NIL was also observed on the PM2.5-induced interleukin-8 (IL-8) gene expression both at the transcriptional and protein levels. These results suggest that PM2.5 induces NFκB activity via the pathways involving ROS and/or RNS generation. Considering the fact that NFκB also induces NO generation via iNOS expression, they might make a positive feedback loop that amplifies the downstream responses.

Effect of laser fluence on the deposition and hardnessof boron carbide thin films

We deposited amorphous thin films of boron carbide by pulsed laser deposition using a B4C target at room temperature. As the laser fluence increased from 1 to 3 J/cm2, the number of 0.25–5 μm particulates embedded in the films decreased, and the B/C atomic ratio of the films increased from 1.8 to 3.2. The arrival of melt droplets, atoms, and small molecular species depending on laser fluence appeared to be involved in the film formation. In addition, with increasing fluence the nanoindentation hardness of the films increased from 14 to 32 GPa. We believe that the dominant factor in the observed increase in the films’ hardness is the arrival of highly energetic ions and atoms that results in the formation of denser films.

Study of Coagulant Effect on Shallow-Bed (Traveling-Bridge) Contact Filtration for Effluent Reuse

In this study, a shallow-bed traveling-bridge (SBTB) filter was used as a contact filter, to investigate the effect of coagulant addition to the filtration efficiency. The filter bed was 25 cm deep, containing 0.55 mm quartz sand. 10–15 m3/hr. secondary effluents were filtered at 3.5–5 m/hr. For different alum doses effective removal of particulates up to (70–80%), turbidity (65–70%) and phosphates up to (80–90%) was obtained. The headloss data indicated an increasing surface straining with the addition of alum which, by changing the (aluminum/TSS) ratio, increased the floc volume. For this reason an optimum alum dose range would be 10–15 mg/l. The efficiency of using high molecular weight, medium to high charge density cationic polymers as primary coagulants was also investigated. The medium cationic high molecular weight polymer used as a primary coagulant at a 0.5 mg/l dose was able to efficiently remove &amp;gt; 10 μm particulates but did not significantly improve turbidity. The same polymer used at a 3 mg/l dose improved the removal of the whole range of particles. By using a high cationic high molecular weight polymer as a secondary coagulant it was possible to decrease the alum dose necessary for an efficient filtration.

Study of coagulant effect on shallow-bed (traveling-bridge) contact filtration for effluent reuse

In this study, a shallow-bed traveling-bridge (SBTB) filter was used as a contact filter, to investigate the effect of coagulant addition to the filtration efficiency. The filter bed was 23 cm deep, containing 0.55 mm quartz sand. 10–15 m3/hr. secondary effluents were filtered at 3.5–5 m/hr. For different alum doses effective removal of particulates up to (70–80%), turbidity (65–70%) and phosphates up to (80–90%) was obtained. The headloss data indicated an increasing surface straining with the addition of alum which, by changing the (aluminium/TSS) ratio, increased the floc volume. For this reason an optimum alum dose range would be 10–15 mg/l. The efficiency of using high molecular weight, medium to high charge density cationic polymers as primary coagulants was also investigated. The medium cationic high molecular weight polymer used as a primary coagulant at a 0.5 mg/l dose was able to efficiently remove > 10 μm particulates but did not significantly improve turbidity. The same polymer used at a 3 mg/l dose improved the removal of the whole range of particles. By using a high cationic high molecular weight polymer as a secondary coagulant it was possible to decrease the alum dose necessary for an efficient filtration.

Effects of iron and chelation on Lake Kinneret bacteria

The response of natural populations of bacteria (prepared by passing Lake Kinneret water through 1 μm filters) to additions of Fe(2+) and/or the chelator ethylenediaminetetraacetic acid (EDTA) was followed by measuring the incorporation of (3)H-thymidine into >0.2 μm particulates, and also by determining the increments in cell numbers after 24 h. In most cases, a stimulation of (3)H-thymidine incorporation was observed in supplemented samples relative to untreated controls after 3 and 24 h incubation. The increase in bacterial numbers was also enhanced by these supplements. Generally, EDTA alone evoked a greater stimulation than Fe(2+); combined supplements gave no further increase. This response pattern appeared consistently throughout the year in samples taken from near-surface lake waters. These results suggest that the availability of iron or chelators may play an important role in regulating bacterial metabolism and growth even in aquatic ecosystems like Lake Kinneret where ambient concentrations of total Fe are relatively high.

The effect of background particulates on the delayed transition of a heated 9:1 ellipsoid

An experimental study was done to quantify the effects of a variety of background particulates on the delayed laminar-turbulent transition of a thermally stabilized boundary layer in water. A Laser-Doppler Velocimeter system was used to measure the location of boundary layer transition on a 50 mm diameter, 9:1 fineness ratio ellipsoid. The ellipsoid had a 0.15 μm RMS surface finish. Boundary layer transition locations were determined for length Reynolds numbers ranging from 3.0 × 106 to 7.5 × 106. The ellipsoid was tested in three different heating conditions in water seeded with particles of four distinct size ranges. For each level of boundary layer heating, measurements of transition were made for “clean” water and subsequently, water seeded with 12.5 μm, 38.9 μm, 85.5 μm and 123.2 μm particles, alternately. The three surface heating conditions tested were no heating, ΔT = 10°C and ΔT = 15°C where ΔT is the difference between the inlet model heating water temperature, Ti, and free stream water temperature, T∞. The effects of particle concentration were studied for 85.5 μm and 123.2 μm particulates.

Sulfur chemistry in a copper smelter plume

Sulfur transformation chemistry was studied in the plume of the Utah smelter of Kennecott Copper Corporation from April to October 1977. Samples were taken at up to four locations from 4 to 60 km from the stacks. Data collected at each station included: SO 2 concentration, low-volume collected total paniculate matter, high-volume collected size fractionated paniculate matter, wind velocity and direction, temperature, and relative humidity. Paniculate samples were analyzed for S(IV). sulfate, strong acid, anions, cations, and elemental concentrations using calorimetric, ion Chromatographie, FIXE, ESCA, ion microprobe, and SEM-ion microprobe techniques. The concentration of As in the paniculate matter was used as a conservative plume tracer. The ratios Mo/As, Pb/As, and Zn/As were constant in particulate matter collected at all sampling sites for any particle size. Strong mineral acid was neutralized by background metal oxide and/or carbonate particulates within 40km of the smelter. This neutralization process is limited only by the rate of incorporation of basic material into the plume. Two distinct metal-S(IV) species similar to those observed in laboratory aerosol experiments were found in the plume. The formation of paniculate S(IV) species occurs by interaction of SO 2 (g) with both ambient and plume derived aerosol and is equilibrium controlled. The extent of formation of S(IV) complexes in the aerosol is directly proportional to the SO 2(g) and paniculate (Cu + Fe) concentration and inversely proportional to the paniculate acidity. S(IV) species were stable in collected paniculate matter only in the neutralized material, but with proper sampling techniques could be demonstrated to also be present in very acidic particles at high ambient SO 2(g) concentrations. Reduction of arsenate to arsenite by the aerosol S(IV) complexes during plume transport is suggested. The SO 2(g)-sulfate conversion process in the plume is described by a mechanism which is first order in SO 2(g). Equations are derived describing sulfur chemistry when both S(IV) and sulfate formation occur in a plume. The formation of sulfate results primarily in the formation of < 0.5 μm particulates. The formation process is not correlated with plume expansion, paniculate acidity, metal content, or S(IV) species. Due to meteorological restrictions on sampling, data were collected only during periods of maximum insolation. The formation of sulfate from SO 2(g) in the plume during periods of high insolation is temperature dependent with an apparent activation energy of 16.6 ± 1.4 kcal mol −1 and a k 1, value of 0.039h −1 at 25°C.