Chemical Properties Of Particles Research Articles

Particulate emissions from cooking: emission factors, emission dynamics, and mass spectrometric analysis for different cooking methods

Abstract. Since most people, especially in developed countries, spend most of their time indoors, they are heavily exposed to indoor aerosols, which can potentially lead to adverse health effects. A major source of indoor aerosols are cooking activities, which release large quantities of particulate emissions (in terms of both number and mass), often with complex compositions. To investigate the characteristics of cooking emissions and what influences these emissions, we conducted a comprehensive study by cooking 19 dishes with different ingredients and cooking methods. The emissions were monitored in real time with several online instruments that measured both physical and chemical particle properties as well as trace gas concentrations. The same instrumentation was used to study the influence of cooking emissions on the ambient aerosol load at two German Christmas markets. In contrast to previous studies, which often focus on individual aspects or emission variables, this broad and coherent approach allows a comparison of the influence of different parameters (e.g., ingredients, cooking method, cooking temperature, cooking activities) on the emissions. We found an influence of cooking emissions on six variables: number concentration of smaller (particle diameter dp > 5 nm) and larger (dp > 250 nm) particles, particulate matter (PM: PM1, PM2.5, PM10), black carbon (BC), PAHs (polycyclic aromatic hydrocarbons), and organic aerosol mass concentration. In general, similar emission characteristics were observed for dishes with the same cooking method, mainly due to similar cooking temperature and use of oil. The temporal dynamics in the emissions of the aforementioned variables, as well as the sizes of the emitted particles, were mainly influenced by the cooking temperature and the activities during cooking. Emissions were quantified using emission factors, with the highest values for grilled dishes, 1 to 2 orders of magnitude lower for oil-based cooking (baking, stir-frying, deep-frying), and the lowest for boiled dishes. For the identification of cooking emissions with the Aerodyne aerosol mass spectrometer (AMS), and more generally for the identification of new AMS markers for individual organic aerosol types, we propose a new plot type that takes into account the mass spectral variability for individual aerosol types. Combining our results and those of previous studies for the quantification of cooking-related organic aerosols with the AMS, we recommend the use of relative ionization efficiency values higher than the default value for organics (RIEOrg = 1.4): 2.17 ± 0.48 for rapeseed-oil-based cooking and 5.16 ± 0.77 for soybean-oil-based cooking.

Measurement and Modeling of Ship-Related Ultrafine Particles and Secondary Organic Aerosols in a Mediterranean Port City.

Maritime transport emerges as a major source of ultrafine particle (UFP) pollution in coastal regions with consequences for the health of people living in port cities. Inhalation of UFPs can cause inflammation and oxidative stress, which are starting points for further diseases. In addition to primary particles, secondary organic aerosol (SOA) may form through the photo-oxidation of volatile organic compounds emitted in ship exhaust. The characterization of size-segregated and chemical properties of particles is essential for assessing the health implications related to shipping. We applied a coupled regional-local chemistry transport modeling system to study the effects of ship emissions on atmospheric concentrations of UFP and SOA in the Mediterranean port city Marseille (France), which is characterized by the combination of high port activity, industrialized emissions, and active photochemistry in summer. Our results show that the average potential impact from local shipping in the port area was 6-9% for SOA and 27-51% for total particle number concentration in July 2020. The estimated oxidative potential of daily mean particulate organic matter related to shipping was lower than the oxidative potential reported for heavy fuel oil (HFO). The lower oxidative potential in this study is very likely due to the low share of ships using HFO during stopover.

Influence of the Physical and Chemical Properties of Particles on the Thermal Conductivity of Polymer Composite Materials

Influence of the Physical and Chemical Properties of Particles on the Thermal Conductivity of Polymer Composite Materials

Industrial Fire Detector Using Colour Detection and Tracking

Conventional fire detection systems use physical sensors to detect fire. Chemical properties of particles in the air are acquired by sensors and are used by conventional fire detection systems to raise an alarm. However, this can also cause false alarms; for example, a person smoking in a room may trigger a typical fire alarm system. In order to manage false alarms of conventional fire detection systems, a computer vision-based fire detection algorithm is proposed in this paper. The proposed fire detection algorithm consists of two main parts: fire color modeling and motion detection. The algorithm can be used in parallel with conventional fire detection systems to reduce false alarms. It can also be deployed as a stand-alone system to detect fire by using video frames acquired through a video acquisition system.

Relationship Between Particle Properties and Immunotoxicological Effects of Environmentally-Sourced Microplastics

BackgroundConcerns on microplastics (MPs) in food are increasing because of our increased awareness of daily exposure and our knowledge gap on their potential adverse health effects. When particles are ingested, macrophages play an important role in scavenging them, potentially leading to an unwanted immune response. To elucidate the adverse effects of MPs on human health, insights in the immunotoxicity of MPs are essential.ObjectivesTo assess the effect of environmentally collected ocean and land weathered MP particles on the immunological response of macrophages using a state-of-the art in vitro immunotoxicity assay specifically designed for measuring particle toxicity.MethodsEnvironmentally-weathered macroplastic samples were collected from the North Pacific Subtropical Gyre and from the French coastal environment. Macroplastics were identified using (micro)Raman-spectrometry, FT-IR and Py-GC-MS and cryo-milled to obtain size-fractionated samples up to 300 μm. Physiochemical MP properties were characterized using phase contrast microscopy, gel-permeation chromatography, nuclear magnetic resonance, and differential scanning colorimetry. Macrophages (differentiated THP-1 cells) were exposed to particles (<300 μm) for 48 h before assessment of cell viability and cytokine release. Using both the physiochemical particle properties and biological data, we performed multi-dimensional data analysis to explore relationships between particle properties and immunotoxicological effects.ResultsWe investigated land-derived polyethylene, polypropylene, polystyrene, and polyethylene terephthalate, water-derived polypropylene macroplastics, and virgin polyethylene fibers and nylon MPs. The different plastic polymeric compositions and MP size classes induced distinct cytokine responses. Macrophages had the largest response to polyethylene terephthalate-particle exposure, including a dose-related increase in IL-1β, IL-8, and TNF-α secretion. Smaller MPs induced cytokine production at lower concentrations. Additionally, a relationship between both physical and chemical particle properties and the inflammatory response of macrophages was found.DiscussionThis research shows that MP exposure could lead to an inflammatory response in vitro, depending on MP material and size. Whether this implies a risk to human health needs to be further explored.

Preparation of silicon and aluminum nanoparticles in an aqueous solution

The interest in nanomaterials is due to a significant change in their physical properties compared to massive materials. Changes in the physical and chemical properties of particles containing several hundred or thousands of atoms are determined by changes in the density of electronic states.Aqueous solutions of aluminum and silicon nanoparticles were obtained by laser ablation. Pulsed laser treatment was performed in the mode of double pulses in distilled water. The invested energy was: for aluminum 1000–1500 J, the exposure time is 10–25 min., for silicon-50–1000 J with exposure times from 1 to 10 min.The features of the morphology of the obtained particles, as well as the surface of polycrystalline aluminum and silicon craters, were determined by scanning electron microscopy. It is shown that an ensemble of particles of different sizes from 20 nm to 2.0 microns is formed. Some aluminum particles are cut, which allows us to talk about their cristallinity. It is shown that the structure of the target surface after laser exposure consists of grains separated from each other by thermal etching grooves, since the evaporation of the material occurs primarily along the grain boundaries.

Effect of concentration of PEG coated gold nanoparticle on lung surfactant studied with coarse-grained molecular dynamics simulations

The surface modification of nanoparticles can not only change the physical and chemical properties of particles, such as the hydrophilic and hydrophobic properties and surface charges of nanoparticles to a certain extent, but also bring new functions to nanoparticles, such as membrane permeability and targeting. Inhaled nanoparticles (NPs) are experienced by the first biological barrier inside the alveolus known as lung surfactant (LS), consisting of phospholipids and proteins in the form of the monolayer at the air-water interface. Inhaled NPs can reach deep into the lungs and interfere with the biophysical properties of the lung components. The interaction mechanisms of bare gold nanoparticles (AuNPs) with the LS monolayer are not well understood. Coarse-grained molecular dynamics simulations were carried out to have a study on the interactions of PEG coated AuNPs with LS monolayers. It was observed that the interactions of AuNPs and LS components make the monolayer structure deform and change the biophysical properties of LS monolayer. The results also indicate that AuNPs with high concentrations hinder the lowering of the LS surface tension and reduce lateral mobility of lipids. Overall, the simulation results can provide guidance for the design of ligand protected NPs as drug carriers and can identify the nanoparticles potential side effect on lung surfactant.

The Influence of Selected Properties of Particles in the Jigging Process of Aggregates on an Example of Chalcedonite

The influence of the physical, geometric and chemical properties of particles on the results of aggregate separation by means of a laboratory ring jig is presented in this paper. The experiment was based on separation of chalcedonite particles in a narrow particle size fraction composed separately of regular and irregular particles, which was prepared in accordance with patent inventions. On its basis, the geometric properties—projection diameter and (volumetric and dynamic) shape coefficients—as well as physical properties—particle density—were determined in products of the regular and irregular particles. The terminal settling velocities of the regular and irregular particles were calculated for a randomly selected sample of particles in each obtained separation product. The statistical analysis of the geometric properties of the particles allowed to evaluate the influence of these parameters on aggregate processing with respect to selection of particles homogenous in terms of their shapes. The comparison of the particle shapes’ influence on the chalcedonite feed separation effects was made by the means of the values of the shape coefficients: the dynamic and volumetric ones. Additionally, tests were carried out using Raman spectroscopy in order to determine the mechanisms of density change in the aggregate. The research goal was realised through detecting and analysing the polymorphic forms of the silica and allogenic minerals precipitated on the surface and inside the chalcedonite particles.

Effect of physico-chemical properties of road deposit sediments on BTEX accumulation

Few studies have investigated on accumulation of benzene series pollutants (benzene, toluene, ethylbenzene and xylene, BTEX) on urban road surfaces as well as the relationship between BTEX accumulation and physio-chemical properties of road deposit sediment particles. In this paper, seventeen typical urban road sites in Henggang Street of Longgang District, Shenzhen city, were selected to analyze BTEX loads. These selected road sites covered different urban functional districts (commercial, industrial and residential) and different road types (common roads and road junctions). The accumulated particle samples were collected on the selected roads using a dry and wet vacuuming method and these samples were tested for BTEXs by a gas chromatography-mass spectrometer. The physico-chemical properties of particles such as particle size distribution, mineral content and chemical oxygen demand (COD) were tested. The effect of the cumulative load of BTEX particles on physical and chemical properties of particles was analyzed by using principal component analysis (PCA). The results indicate that build-up loads of BTEXs with particles size <150 μm are higher than those of BTEX particles with particle size > 150 μm; quartz is the main mineral in all particles with different particle sizes; the COD loads attached on fine particles are much higher than those on coarse particles; berlinite could be an important carrier of BTEXs on road surfaces. These results can provide useful insights to ensure stormwater reuse safety and safeguard urban water environment.

Effects of chemical composition and carbon residue on removal of coal-fired particles by vapor condensation

Vapor condensation on coal-fired fine particles is one of the most promising preconditioning technique for fine particles removal. The physical and chemical properties of particles is one of the major factors governing this process. In order to investigate the effects of chemical composition and carbon residue of coal-fired fine particles on this process, in this work, the connection of particle’s surface wettability with the chemical compositions and carbon residue was established. The results showed that coal-fired particle’s surface wettability was affected by the major compositions of the particle as follows: Al2O3, SiO2, SO3, CaO and Fe2O3, and the carbon residue had a negative effect on particle’s surface wettability which was proportional to the carbon residue fraction. The experiments of particle enlargement under supersaturated vapor environment showed that the performance of particle enlargement was related to the chemical compositions and carbon residue. We could conclude that chemical compositions, carbon residue affect condensation of water vapor on coal-fired fine particles in such a way that the chemical compositions and carbon residue determined the wettability of the particle surface, thus different enlargement performance was presented.

Resolving nanoparticle growth mechanisms from size- and time-dependent growth rate analysis

Abstract. Atmospheric new particle formation occurs frequently in the global atmosphere and may play a crucial role in climate by affecting cloud properties. The relevance of newly formed nanoparticles depends largely on the dynamics governing their initial formation and growth to sizes where they become important for cloud microphysics. One key to the proper understanding of nanoparticle effects on climate is therefore hidden in the growth mechanisms. In this study we have developed and successfully tested two independent methods based on the aerosol general dynamics equation, allowing detailed retrieval of time- and size-dependent nanoparticle growth rates. Both methods were used to analyze particle formation from two different biogenic precursor vapors in controlled chamber experiments. Our results suggest that growth rates below 10 nm show much more variation than is currently thought and pin down the decisive size range of growth at around 5 nm where in-depth studies of physical and chemical particle properties are needed.

Tunable particles alter macrophage uptake based on combinatorial effects of physical properties.

The ability to tune phagocytosis of particle‐based therapeutics by macrophages can enhance their delivery to macrophages or reduce their phagocytic susceptibility for delivery to non‐phagocytic cells. Since phagocytosis is affected by the physical and chemical properties of particles, it is crucial to identify any interplay between physical properties of particles in altering phagocytic interactions. The combinatorial effect of physical properties size, shape and stiffness was investigated on Fc receptor mediated macrophage interactions by fabrication of layer‐by‐layer tunable particles of constant surface chemistry. Our results highlight how changing particle stiffness affects phagocytic interaction intricately when combined with varying size or shape. Increase in size plays a dominant role over reduction in stiffness in reducing internalization by macrophages for spherical particles. Internalization of rod‐shaped, but not spherical particles, was highly dependent on stiffness. These particles demonstrate the interplay between size, shape and stiffness in interactions of Fc‐functionalized particles with macrophages during phagocytosis.

Mechanism of Ultrasonic Introduction of Particles into a Poorly Wetting Liquid

The process of introduction of submicron agglomerates and nanostructured particles into a poorly wetting liquid exposed to ultrasound is theoretically considered. The main dependences relating the exposure time to the physical and chemical properties of particles and liquid as well as to the characteristics of acoustic radiation are obtained.

On the Mechanism of Ultrasound-Driven Deagglomeration of Nanoparticle Agglomerates in Aluminum Melt

One of the promising directions in the technology of composite alloys with improved mechanical properties is reinforcement of the metallic matrix with nanopowders introduced in the liquid metal. Ultrasonic processing is known to significantly improve the introduction of submicrone particles to the metallic melt. This study focuses on the mechanisms of deagglomeration and wettability of such particles by the melt under the action of ultrasound. The suggested mechanism involves the penetration of the liquid metal into the pores and cracks of the agglomerates under the excess pressure created by imploding cavitation bubbles and further destruction of the agglomerate by the sound wave. The main dependences connecting the acoustic parameters and processing time with the physical and chemical properties of particles and the melt are obtained through analytical modeling. The mathematical description of the ultrasonic deagglomeration in liquid metal is presented; a dependence of the threshold intensity of ultrasound for the break-up of agglomerates on their size is reported.

Physicochemical evolution of nascent soot particles in a laminar premixed flame: from nucleation to early growth

In this work, particle inception and early growth stages were investigated in an ethylene/air premixed flame by the evolution of the particle size and structure with flame residence time. Particle size distribution was measured by a scanning mobility particle seizer and chemical–physical investigation was carried out by Raman microspectroscopy, UV–visible light absorption and cyclic voltammetry.From early inception of particles, just downstream the flame front, to the formation of primary soot particles, in the post-oxidation flame zone, particles participate in a series of chemical and physical reactions that strongly modify their nanostructure and physicochemical properties, resulting in different optical and electronic characteristics. The results presented in this study show that the evolution from a mono-modal to a bi-modal size distribution is associated to a particle graphitization process consisting of a slight increase of the in plane average size of the polyaromatic units within the particles, La, and on the formation of stacks of polyaromatic planes. These outcomes suggest that in our flame conditions particle coagulation/coalescence has a major role in the initial soot formation, affecting both physical and chemical particle properties.

Theoretical analysis of a method to measure size distributions of solid particles in water by aerosolization

Reliable measurement of the size-resolved number concentration (size distribution) of solid particles dispersed in water or melted ice is of critical importance in many geoscientific observational studies. Because physical and chemical properties of particles can be measured more unambiguously and accurately in rarefied media (air) than in condensed media (water), particle measurement after aerosolization using a nebulizer is a significant method for the observation of solid particles dispersed in water. We propose a mathematical theory for estimating the original size distribution of solid particles in water from the measured size distribution of aerosolized particles. We assume that the size distribution of water droplets produced by a nebulizer is given. The size distribution of solid particles in water can be estimated by solving a system of nonlinear equations. The complexity in solving the equations increases rapidly with the computational resolution of particle size and the assumed maximum number of particles within each droplet. For such a system of equations, we found rigorous error bounds of a true solution using INTLAB, an interval arithmetic package. Our theoretical framework will be useful in many fields in geoscience as a fundamental scheme to quantify solid particles in water. In particular, an application of the proposed theoretical method is shown to be useful for the quantitative observations of the size distribution of black carbon particles in rainwater.

Effect of ionic strength and permeate flux on membrane fouling: Analysis of forces acting on particle deposit and cake formation

In Cross-Flow Microfiltration (CFMF), suspended particles deposit to form a cake layer on the membrane surface, which provides a resistance to permeate flow. The cake resistance, which plays an important role on the performance of CFMF, is mainly determined by the packing porosity of the cake and, the physical and chemical properties of particles. This study aimed at understanding the porosity and the specific filtration resistance of the cake for a given condition. These properties have been studied using experiments under a constant permeate flux. Factors such as permeate flux and ionic strength were investigated in terms of the particles deposition and cake formation. This study also adopted a force balance model to predict the deposit rate of particles and then compare with the experimental results. Inter-particle forces (electric double layer repulsion force and Van der Waals attraction force) were incorporated into the calculation of cake structure (cake porosity and specific resistance) together with the equilibrium condition of hydrodynamic forces. The experimental results showed that the higher the permeate flux led to the greater amount of particles deposit and the denser structure of cake. The porosity of cake decreased with the increase in ionic strength (0∼0.01M) and then increased sharply afterwards (0.01∼0.1M). The hydrodynamic force balance model estimated well the tendency of variation in cake structure depending on the ionic strength.

Real-time calibration of a feedback trap.

Feedback traps use closed-loop control to trap or manipulate small particles and molecules in solution. They have been applied to the measurement of physical and chemical properties of particles and to explore fundamental questions in the non-equilibrium statistical mechanics of small systems. These applications have been hampered by drifts in the electric forces used to manipulate the particles. Although the drifts are small for measurements on the order of seconds, they dominate on time scales of minutes or slower. Here, we show that a recursive maximum likelihood (RML) algorithm can allow real-time measurement and control of electric and stochastic forces over time scales of hours. Simulations show that the RML algorithm recovers known parameters accurately. Experimental estimates of diffusion coefficients are also consistent with expected physical properties.

Synthesis and photocatalytic properties of bismuth titanate with different structures via oxidant peroxo method (OPM)

Bismuth titanate (Bi4Ti3O12 and Bi12TiO20) powders were synthesized by the Oxidant Peroxide Method (OPM), and the effect of temperatures on physical and chemical properties of particles was investigated. The results showed that the morphology and average particle size of materials can be successfully controlled by adjusting the temperature. The samples after calcination were characterized by X-ray diffractometry, transmission electron microscopy, diffuse reflectance spectroscopy, Raman spectroscopy, and BET isotherms. The photocatalytic activity of materials was also evaluated by studying the degradation of 10ppm aqueous rhodamine B dye under ultraviolet radiation.

Vision based Fire Detection and Robot Maneuvering Algorithm

based fire detection is potentially a useful technique. With the increase in the number of surveillance cameras being installed, a vision based fire detection capability can be incorporated in existing surveillance systems at relatively low additional cost. Vision based fire detection offers advantages over the traditional methods. It will thus complement the existing devices. Conventional fire detection systems use physical sensors to detect fire. Chemical properties of particles in the air are acquired by sensors and are used by conventional fire detection systems to raise an alarm. However, this can also cause false alarms; for example, a person smoking in a room may trigger a typical fire alarm system. In order to manage false alarms of conventional fire detection systems, a computer vision-based fire detection algorithm is proposed in this paper. The proposed system consists of two main parts: fire color modeling and robot navigation. The algorithm can be used in parallel with conventional fire detection systems to reduce false alarms in order to rescue indoor appliances. It can also be deployed as a stand-alone system to detect fire by using video frames acquired through a video acquisition device. A fire color model is developed in RGB color space to identify fire pixels. The proposed fire color model is tested with video sequences captured in different illumination condition in indoor ambience. The experimental results are quite encouraging in terms of correctly classifying fire pixels according to color information only. In addition; the navigation of the robot is tested through a simulated environment. General Terms