Composite Particles Research Articles

Comment on “Size-Resolved Elemental Composition of Respiratory Particles in Three Healthy Subjects”

Comment on “Size-Resolved Elemental Composition of Respiratory Particles in Three Healthy Subjects”

Study of the content of volatile species in the composition of atmospheric particles on the basis of thermal impact and recording by optical counters

Study of the content of volatile species in the composition of atmospheric particles on the basis of thermal impact and recording by optical counters

Possibilities of spectral analysis methods for the oil sludge research

The paper considers the problem of utilisation and neutralisation of oil sludge at oil producing and refining enterprises. Oil sludge is a complex heterogeneous mixture consisting of high-molecular oil compounds, mineral particles of different composition, and water. The authors studied the elemental composition of oil sludge of different storage periods for oil refinery production by modern analytical methods: IR spectroscopy and X-ray fluorescence spectrometry. According to the research, the main composition of the oil residue, represented by the hydrocarbon component, contains paraffin-naphthenic and heavy aromatic hydrocarbons. Moreover, its non-hydrocarbon component contains compounds Si, Al, Ca, Fe, S, Ba.

The seasonal variation of Asian dust, anthropogenic PM, and their sources in Dushanbe, Tajikistan

Central Asia's arid climate and growing population make it susceptible to air pollution from mineral dust and anthropogenic sources. To assess the impact of these pollution sources on local air quality, the chemical composition of PM10 aerosol particles was collected within a year at Dushanbe, Tajikistan. Primary sources of the pollutants, their impact on PM10 composition, and their seasonal trends were assessed. The measurement approach employed analysis of trace metals, ions, organic compounds, laboratory investigations, diagnostic ratio calculations, all complemented by positive matrix factor analysis. The results reveal that for about 70% of the year, PM10 levels (80 ± 55 μg m−3 as the annual average) in Dushanbe were higher than the WHO limits, with varying levels during the seasons. Summer concentrations peaked up to 434 μg m−3 due to a combined mineral and road dust influence. Interestingly, winter concentrations reached 152 μg m−3 due to strong contributions (about 64%) from residential heating and fossil fuel combustion, often triggered during sub-10 °C temperatures. Mineral dust events were associated with elevated concentrations of trace metals, including Zn and Pb, alongside organic carbon and high-chain n - alkanes. During such events, Ca/Fe, Ca/Al ratios exceeded those of Saharan dust, suggesting a high salt content in Asian dust, potentially influenced by dried-off lake emissions. It was striking to observe that winter periods exhibited concerning levels of carcinogenic PAHs, such as benzo(b)fluoranthene (<25 ng m−3) and benzo[a]pyrene (<12 ng m−3, BaP), with average values of 4.1 ± 5.9 ng m−3 (BaP) that significantly exceed WHO recommendations. The high PM10 and PAH exposure could pose severe health risks, necessitating collective attention from the local authorities in developing new mitigation strategies concerning the reduction of emissions from residential heating of coal and wood in winter to curb combustion emissions and reduce exposure.

Refractometric method to study the coating thickness of diamond nanoparticles

A method based on refractometric measurements of liquid nanodisperse systems has been developed to determine the quantitative composition of diamond-amorphous carbon colloidal particles. It was demonstrated that by measuring the changes in the refractive index and density of sols caused by changes in particle concentration it is possible to determine the thickness of the particle surface layer, assuming its composition is known. Within the framework of the Mie theory, the influence of the size of diamond particles with carbon coating on the refractive index of hydrosols was quantified. The limits of applicability of the developed method have been determined. For several polydisperse sols with coated diamond particles the thickness of carbon coating was determined.

High-resolution sampling in the eastern tropical North Atlantic reveals episodic Saharan dust deposition: implications for the marine carbon sink

In this study we present data collected between August 2017 and December 2018 from submarine sediment trap M1 located in the eastern tropical North Atlantic and determine lithogenic and biogenic fluxes, and grain-size distributions of aerosol dust. An unprecedented high sampling resolution of four days in combination with satellite imagery allowed the identification of thirteen major dust events of two types within the 468-day series. Seven dust events were classified as high-flux events identified by a deposition of &amp;gt;=25 mg m-2 d-1. The average dust deposition rate increased by 461.3% during these types of events. The remaining six events were characterized by a high composition of giant particles (&amp;gt;7.3 vol%). Seasonal variations of dust flux were recorded, with highest fluxes observed in spring at an average deposition rate of 14.8 mg m-2 d-1, and lowest fluxes in fall with an average rate of 8.6 mg m-2 d-1. The estimated total dust flux in the tropical North Atlantic was 4040.02 mg m-2 y-1. We suggest that most of the summer dust was likely transported over the sampling site at high altitudes while winter transport occurred closer to the sea surface, resulting in generally higher background fluxes. Grain-size distributions exhibited seasonal variations with increased occurrences of giant particles (&amp;gt;62.5 μm) in fall 2017 and spring, and less occurrences in winter and fall 2018. Grain-size sorting was high in spring and most variable in summer. Precipitation did not affect depositional fluxes or grain-size distributions of the aeolian dust significantly. Organic matter was deposited continuously at the sampling site with a deposition rate ranging from 14.4–862.25 mg m-2 d-1. Organic matter fluxes increased by 199.5% during high-flux dust events but decreased by 13.6% during anomalous grain-size events. Spring experienced the highest number of dust events (n=5). This unprecedented high-resolution dataset of dust deposition in marine sediment-traps enabled the distinction of dust events and their relation to organic matter flux. This suggests the possibility of a dust fertilization or mineral ballasting effect.

Ni/Graphene Coating for Enhanced Corrosion Resistance of Metal Foam Flow Field in Simulated PEMFC Cathode Environment.

Metal foam flow field suffers serious corrosion issues in proton exchange membrane fuel cells due to its large surface area. Ni and Ni/graphene coatings are prepared under constant and gradient current modes, respectively, to improve the corrosion resistance. The effect of the electrodeposition current mode and the deposition mechanism is studied. Compared with Ni coating, Ni/graphene coating brings low corrosion current density and high coating resistance, effectively enhancing the stability of Ni foam in an acidic environment. Different from Ni coating with a single layer, Ni/graphene deposits have core-shell structure, with graphene coated on the surface of Ni nanoparticles. It is shown that graphene deposits cover the Ni particles during the electrodeposition, which protects nickel particles from agglomeration and forms an inert film on the surface of the porous structure. After an 8 h constant potential test, no significant pitting is observed on the surface of Ni/graphene coating, showing excellent anticorrosion performance. As to the effect of the deposition current mode, it is shown that more composite particles deposit on the upper layer under the gradient current mode, which brings denser protective film and fewer surface defects on the surface. Ni/graphene coating electrodeposited under a gradient current mode between 0 and 10 mA·cm-2 exhibits the lowest corrosion current densities. The values at 50 and 80 °C are only 62.9 and 26.0% of those of uncoated Ni foam, respectively.

Impacts of temperature and fluid seepage on organic matter composition in sediments of an active hydrothermal basin

Marine sediments are one of the largest organic carbon (OC) sinks on Earth. Yet, major knowledge gaps remain in our understanding of sedimentary OC cycling, particularly regarding temperature-induced alteration processes of OC from different sources. Here, we investigate OC-rich sediments of Guaymas Basin (Gulf of California) across two hydrothermal areas, one with only conductive geothermal heating and the other additionally experiencing seepage of hydrocarbon-rich fluids from deeper layers. We use Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) to investigate diagenetic OC changes and show that cold control sites in both hydrothermal areas are dominated by similar contributions of lipid-derived compounds, nitrogenous (likely protein-derived) compounds, carbohydrates, and polyaromatic hydrocarbons (PAHs). These OC compound groups are largely derived from phytoplankton detritus from overlying water. Conductively heated sediments, which reach in situ temperatures of ∼ 80 °C, have similar general OC compositions and contents to these cold sites, but show evidence of diagenetic modifications of individual carbohydrate groups in deeper layers. By contrast, strong decreases in carbohydrate and nitrogenous compound abundances at the seep sites indicate that these compound groups are not only modified but also selectively degraded at the higher temperatures (>80 °C) of these sites. Increases in pyrolysis products of PAHs, prist-1-ene, and alkanes with depth, moreover, show that import of OC by deep hydrothermal fluids contributes significantly to sedimentary OC pools mainly in deeper layers of these sites. Our study provides the first comprehensive analysis of major OC compound groups in Guaymas Basin sediment and indicates that the supply of OC by hydrothermal fluid flow only has minor impacts on particulate organic matter compositions at the seafloor, even at active seep sites. We furthermore show that temperatures up to ∼ 80 °C already result in thermochemical modifications of organic matter (OM) that are potentially linked to the onset of kerogen formation. The sequence and time scales of chemical modifications and activations in relation to temperature are an important subject for future investigations.

Enhanced thermochemical energy storage properties of SiC-doped calcium-based material with steam addition during heat charging process

Thermochemical energy storage based on the reversible carbonation/calcination reaction of CaCO3/CaO is emerging as a promising technology for energy storage in concentrating solar power systems. However, the inherent weak solar absorption capacity of natural calcium-based materials necessitates a substantial enhancement in their solar absorption capability. In this study, dark SiC particles of different sizes were introduced into CaO-based composite particles supplemented with cement and microcrystalline cellulose. The aim was to explore the influence of SiC components on the solar absorptivity, energy storage capacity, thermal conductivity, and mechanical properties of CaO-based particles. The results indicate that doping 10 wt% of SiC with a size of 25 μm in CaO-based particles demonstrated optimal results, corresponding to a 20.3 % increase in the average optical absorption and a 2.86-fold improvement in the thermal conductivity compared to the undoped particles. Furthermore, introducing steam during the decomposition of SiC-doped CaO-based particles significantly enhanced the mechanical properties. The breaking force of SiC-doped CaO-based pellets after 50 runs with 10 vol% steam addition was 1.39 times higher than that of the identical particles without steam treatment.

Low Magnetic Field Induced Extrinsic Strains in Multifunctional Particulate Composites: An Interrupted Mechanical Strengthening in 3D-Printed Nanocomposites

Low Magnetic Field Induced Extrinsic Strains in Multifunctional Particulate Composites: An Interrupted Mechanical Strengthening in 3D-Printed Nanocomposites

Tangleoids with quantum field theories in biosystems

Abstract The open question whether quantum field theories can be used in biological systems will be addressed in this study. Quantum effects were reported for certain biological systems like the magnetic orientation sense in migratory birds. In quantum field theories it is possible to derive effective quantum field theories with welded tangleoids including braid relations that describe composite particles based on the dynamics of microscopic particle where these composite particles are made of. We observe that the generators of the tangleoid category that will depict the Feynman graphs are X X for a scattering vertex. This arises after carrying out the integral over bosonic fields A μ {A}_{\mu } in the partition function (D) that will lead to an four-valent interaction vertex generated by a quartic term in the fermionic fields. With X + {X}_{+} and X − {X}_{-} we will depict order changes like that regarding time orderings. Ordinary propagators are depicted by ∪ \cup and ∩ \cap . Finally, the generators ! \&amp;#x0021; and ¡ \hspace{0.1em}\text{&amp;#x00A1;}\hspace{0.1em} come into play if other foreign fields are picked up.

Technical note: Determining chemical composition of atmospheric single particles by a standard-free mass calibration algorithm

Abstract. The chemical composition of individual particles can be revealed by single-particle mass spectrometers (SPMSs). With higher accuracy in the ratio of mass to charge (m/z), more detailed chemical information could be obtained. In SPMSs, the conventional standard-based calibration methods (internal/external) are constrained by the inhomogeneity of ionization lasers and the finite focusing ability of the inlet system, etc.; therefore, the mass accuracy is restricted. In this study, we obtained the detailed and reliable chemical composition of single particles utilizing a standard-free mass calibration algorithm. In the algorithm, the characteristic distributions of hundreds of ions were concluded and collected in a database denoted as prototype. Each single-particle mass spectrum was initially calibrated by a function with specific coefficients. The range of coefficients was constrained by the magnitude of mass deviation to a finite vector space. To find the optimal coefficient vector, the conformity of each initially calibrated spectrum to the prototype dataset was assessed. The optimum calibrated spectrum was obtained with maximum conformity. For more than 98 % ambient particles, a 20-fold improvement in mass accuracy, from ∼ 10 000 ppm (integer) to ∼ 500 ppm (two decimal places), was achieved. The improved mass accuracy validated the determination of adjacent ions with a m/z difference ∼ 0.05 Th. Furthermore, atmospheric particulate trace elements that were poorly studied before are specified. The obtained detailed single-particle-level chemical information could help explain the source apportionment, reaction mechanism, and mixing state of atmospheric particles.

Size, shape, and elemental composition as predictors of microplastic surface erosion

The degradation of surfaces and its possible dependence on shape, size, and elemental composition of plastic particles were subjected. The surfaces of 146 microplastics were classified from smooth to fully eroded (%) by SEM/EDS. Structural elements and various additives were found on microplastics depending on their shapes. The surface of plastic items > 100 µm in length showed a relatively more eroded area than smaller ones, regardless of their shapes. Depending on shape, the percentage of surface erosion of irregularly shaped fragments < 100 µm was significantly enhanced compared to microbeads of the same size. These results may provide insights into assessing potential risks posed by microplastics and improve our understanding of the role of these parameters concerning possible adverse health effects on the environment.

Visible light responsive photocatalytic fuel cell with Ce-UiO-66/g-C3N4/Bi2WO6/Ti photoanode for simultaneous degradation of rhodamine B and electricity generation

In order to enhance the carrier separation efficiency and redox ability of photoanode, a dual Z-scheme heterojunction Ce-UiO-66/g-C3N4/Bi2WO6/Ti photoanode was prepared and assembled with Cu cathode to form PFC. The characterization results show that Ce-UiO-66/g-C3N4/Bi2WO6 uniformly distributed on the Ti substrate, with average crystallite size of 9.04 nm and average particle size of 33.05 nm, which provides sufficient reactive active sites for RhB degradation. The RhB degradation rate, Pmax, Jsc, Voc and FF of the PFC were 90.9 % (90 min), 7.53 µW cm-2, 0.152 mA cm-2, 0.37 V and 0.134, respectively. The turnover frequency (TOF) for RhB degradation by the PFC reached 0.98 h-1. Fermi energy level analysis shows that a double-Z heterojunction is formed between Bi2WO6 and g-C3N4, and between Bi2WO6 and Ce-UiO-66, which not only effectively separates photogenerated e--h+, but also retains the high redox ability of the composite. Moreover, with the introduction of Ce-UiO-66, the composite photoanode has larger specific surface area and wider visible light absorption range. In addition, because of the built-in electric field, the photogenerated electrons can migrate to the surface of composite particles more easily and react with dissolved oxygen to generate more •O2- to participate in the degradation of RhB. This work provides a valuable reference for developing PFC photoanode with high efficiency and visible light response.

Observation-Based Diagnostics of Reactive Nitrogen Recycling through HONO Heterogenous Production: Divergent Implications for Ozone Production and Emission Control.

Understanding of nitrous acid (HONO) production is crucial to photochemical studies, especially in polluted environments like eastern China. In-situ measurements of gaseous and particulate compositions were conducted at a rural coastal site during the 2018 spring Ozone Photochemistry and Export from China Experiment (OPECE). This data set was applied to investigate the recycling of reactive nitrogen through daytime heterogeneous HONO production. Although HONO levels increase during agricultural burning, analysis of the observation data does not indicate more efficient HONO production by agricultural burning aerosols than other anthropogenic aerosols. Box and 1-D modeling analyses reveal the intrinsic relationships between nitrogen dioxide (NO2), particulate nitrate (pNO3), and nitric acid (HNO3), resulting in comparable agreement between observed and simulated HONO concentrations with any one of the three heterogeneous HONO production mechanisms, photosensitized NO2 conversion on aerosols, photolysis of pNO3, and conversion from HNO3. This finding underscores the uncertainties in the mechanistic understanding and quantitative parametrizations of daytime heterogeneous HONO production pathways. Furthermore, the implications for reactive nitrogen recycling, ozone (O3) production, and O3 control strategies vary greatly depending on the HONO production mechanism. On a regional scale, the conversion of HONO from pNO3 can drastically enhance O3 production, while the conversion from NO2 can reduce O3 sensitivity to NOx changes in polluted eastern China.

Enhancing ductility, strength, and hardness of WE43 Mg alloy-based metal matrix composite fabricated via friction stir processing: Effect of hybrid reinforcement and Volume percentage

Pursuing lightweight materials in the automotive and aerospace industries, driven by environmental concerns and fuel efficiency goals, has increased interest in magnesium alloys. The RE-based WE-series exhibits superior properties, making it a compelling candidate for various applications. However, inherent limitations, including low ductility, hardness, and strength, necessitate further enhancements. In this study, an effort is being made to fabricate Metal Matrix Composites (MMCs) through Friction Stir Processing (FSP) using WE43 Mg alloy as matrix and NiTi, Fe, and Sn as hybrid reinforcement particles. The study involved varying the composition of the reinforcement particles, and the analysis of hardness, ductility, and strength was conducted and compared with the base material. The results indicate that the samples processed with hybrid reinforcements using FSP effectively refine the microstructure, leading to improved properties. The highest hardness (81.3 HV), and strength (176 MPa), were observed in the S3 sample. The maximum ductility/strain percentage of 21.9 % was attained in the S2 sample. This research introduces innovative possibilities for expanding the application scope of magnesium alloys, addressing challenges, and capitalizing on their unique properties.

Modulating composite colloidal particle morphology by reaction kinetics in seeded-growth

Modulating composite colloidal particle morphology by reaction kinetics in seeded-growth

Nanoparticle-Based Strategies for Managing Biofilm Infections in Wounds: A Comprehensive Review.

Chronic wounds containing opportunistic bacterial pathogens are a growing problem, as they are the primary cause of morbidity and mortality in developing and developed nations. Bacteria can adhere to almost every surface, forming architecturally complex communities called biofilms that are tolerant to an individual's immune response and traditional treatments. Wound dressings are a primary source and potential treatment avenue for biofilm infections, and research has recently focused on using nanoparticles with antimicrobial activity for infection control. This Review categorizes nanoparticle-based approaches into four main types, each leveraging unique mechanisms against biofilms. Metallic nanoparticles, such as silver and copper, show promising data due to their ability to disrupt bacterial cell membranes and induce oxidative stress, although their effectiveness can vary based on particle size and composition. Phototherapy-based nanoparticles, utilizing either photodynamic or photothermal therapy, offer targeted microbial destruction by generating reactive oxygen species or localized heat, respectively. However, their efficacy depends on the presence of light and oxygen, potentially limiting their use in deeper or more shielded biofilms. Nanoparticles designed to disrupt extracellular polymeric substances directly target the biofilm structure, enhancing the penetration and efficacy of antimicrobial agents. Lastly, nanoparticles that induce biofilm dispersion represent a novel strategy, aiming to weaken the biofilm's defense and restore susceptibility to antimicrobials. While each method has its advantages, the selection of an appropriate nanoparticle-based treatment depends on the specific requirements of the wound environment and the type of biofilm involved. The integration of these nanoparticles into wound dressings not only promises enhanced treatment outcomes but also offers a reduction in the overall use of antibiotics, aligning with the urgent need for innovative solutions in the fight against antibiotic-tolerant infections. The overarching objective of employing these diverse nanoparticle strategies is to replace antibiotics or substantially reduce their required dosages, providing promising avenues for biofilm infection management.

Origins of the seasonal variability of PM2.5 sources in a rural site in Northern France

Air quality in rural areas results from the crossing of aged air masses transported from urban areas with local emissions dominated by agriculture and vegetation. The result is a complex mixture of primary and secondary atmospheric species, coming from varied sources and geographical areas. We implemented a methodology for deconvoluting and determining the geographical origins of the main aerosol sources impacting a typical rural area of northern France. A one-year field campaign was conducted in a rural site located between Paris and Brussels from March 2018 to February 2019. Hourly-based observations of inorganic and organic precursor gases and PM2.5 speciation were collected using on-line instrumentation. The annual PM2.5 concentrations of 12.2 ± 9.23 μg m−3 were explained by four sources extracted through positive matrix factorization analyses: combustion (40.2%), NO3-rich (26.8%), SO4-rich (18%) and mixed aged marine (15%). The combustion and SIA-rich sources drive 85 % of the yearly PM2.5 mass and variability. The combustion factor was most prominent during winter (53.3% of PM2.5 mass) due to high contributions from local and regional transport of biomass burning pollutants (winter OC/EC = 6.0; OC-to-OM factor = 2.05). In summer, it was most likely driven by secondary organic aerosol production and agricultural waste burning events (summer OC/EC = 8.6; OC-to-OM factor = 1.85). Comparing with other regional sites, we observed a strong regional background of carbonaceous particles regardless of the site typology. The SIA fraction is dominated by the NO3-rich source compared to the SO4-rich source. In spring, NO3-rich particles dominate PM2.5 (36.9%) due to intense agricultural activity. The temporal variability is driven by transport processes from the Benelux area in a North-to-South gradient of decreasing concentrations. A minor proportion of the NH4NO3 observed seems to be due to the local effects of morning dew and photochemical oxidation of NO2 in the afternoon. HNO3 appears to be the limiting factor for local NH4NO3 formation. PM2.5 toxicity in rural areas with low population densities should be not only addressed based on mass concentration, but also considering the chemical composition of particles as people from rural environments are exposed to high contributions from biomass burning sources and secondary inorganic aerosols triggered by the NH3 excess.

Triglyceride-rich lipoprotein, remnant cholesterol, and apolipoproteins CII, CIII, and E in patients with schizophrenia

Patients with schizophrenia show a disproportionally increased risk of cardiovascular disease. Hypertriglyceridemia is prevalent in this population; however, how this relates to levels of remnant cholesterol, triglyceride (TG)-rich lipoprotein (TRL) particle size and composition, TG turnover, and apolipoprotein (apo) and angiopoietin-like protein (ANGPTL) concentrations is unknown. Fasting levels of cholesterol (total [TC], LDL-C, HDL-C, non-HDL-C and remnant cholesterol) and TG were determined in 110 patients diagnosed with schizophrenia, and 46 healthy controls. TRL particle size, concentration and composition, and β-hydroxybutyrate (TG turnover marker) were assessed by NMR. Levels of apoCII, apoCIII, apoE, ANGPTL3, ANGPTL4, and ANGPTL8 were measured by ELISA, and apoCII, apoCIII and apoE were further evaluated in HDL and non-HDL fractions. Patients with schizophrenia had significantly elevated TG, TG:apoB ratio, non-HDL-C, remnant cholesterol, non-HDL-apoCII and non-HDL-apoCIII, and HDL-apoE (all P < 0.05), lower HDL-C and apoA-I (all P < 0.001), and comparable apoB, TC, TC:apoB ratio, LDL-C, β-hydroxybutyrate, ANGPTL3, ANGPTL4 and ANGPTL8 to healthy controls. Patients had a 12.0- and 2.5-fold increase in the concentration of large and medium TRL particles respectively, but similar cholesterol:TG ratio within each particle. Plasma TG, remnant cholesterol, and large and medium TRL particle concentrations correlated strongly with apoCII, apoCIII, and apoE in the non-HDL fraction, and with apoCIII and apoE in the HDL fraction in patients with schizophrenia. Differences in TG, HDL-C, TRL particle concentrations, apoCIII, and apoE persisted after adjustment for conventional risk factors. These results are consistent with impaired TRL lipolysis and clearance in patients with schizophrenia which may be responsive to targeting apoCIII.