scholarly journals Simulation of multiple-component charged aerosol evolution

2019 ◽  
Author(s):  
◽  
Fernando De La Torre Aguilar
Keyword(s):  
Homogeneous Medium ◽  
Direct Simulation Monte Carlo ◽  
Spherical Particles ◽  
Charge Effects ◽  
Aerosol Dynamics ◽  
Mass Distributions ◽  
Charged Aerosol ◽  
Multiple Component ◽  
Electrostatic Dispersion

The study of the nuclear source term requires the computation of aerosol dynamics. Solutions to the aerosol general dynamic equation (GDE) are difficult to obtain by analytical or numerical methods when more realistic problems are considered. The direct simulation Monte Carlo (DSMC) technique is capable of simulating aerosol evolution reducing simplifications in the implementation of the aerosol GDE. In this work we present a DSMC program for the simulation of multi-component polydisperse aerosol evolution, with the successful integration of the following processes: deposition, electrostatic dispersion, coagulation (considering charge effects) and condensation, assuming a spatially homogeneous medium and spherical particles. Two problems with different particle compositions were simulated to obtain information about the interactions through the different processes and the interacting particles as well as particle number and mass distributions with discrimination of charge levels. This information allowed us to explore the synergistic nature of these processes. It was found that the problem with denser particles had an overall stronger activity in coagulation and initially a stronger activity in deposition compared to the problem with less dense particles. Experiments to generate two-component aerosols by spark discharge in the study of aerosol coagulation with characterization of particle composition are proposed. Moreover, the use of particle weights in the DSMC method is explored.

scholarly journals Deep Learning Based Instance Segmentation of Titanium Dioxide Particles in the Form of Agglomerates in Scanning Electron Microscopy

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 968
Author(s):  
Paul Monchot ◽  
Loïc Coquelin ◽  
Khaled Guerroudj ◽  
Nicolas Feltin ◽  
Alexandra Delvallée ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Titanium Dioxide ◽  
Learning Community ◽  
Spherical Particles ◽  
Average Value ◽  
Size Characterization ◽  
Scanning Electron

The size characterization of particles present in the form of agglomerates in images measured by scanning electron microscopy (SEM) requires a powerful image segmentation tool in order to properly define the boundaries of each particle. In this work, we propose to use an algorithm from the deep statistical learning community, the Mask-RCNN, coupled with transfer learning to overcome the problem of generalization of the commonly used image processing methods such as watershed or active contour. Indeed, the adjustment of the parameters of these algorithms is almost systematically necessary and slows down the automation of the processing chain. The Mask-RCNN is adapted here to the case study and we present results obtained on titanium dioxide samples (non-spherical particles) with a level of performance evaluated by different metrics such as the DICE coefficient, which reaches an average value of 0.95 on the test images.

Preparation and characterization of uniform submicrometer metal niobate particles: Part II. Magnesium niobate and potassium niobate

1992 ◽  
Vol 7 (4) ◽  
pp. 912-918 ◽  
Author(s):  
Myung Jin Kim ◽  
Egon Matijević
Keyword(s):  
Colloidal Particles ◽  
Spherical Particles ◽  
Potassium Niobate ◽  
Homogeneous Precipitation ◽  
Potassium Salts ◽  
Chemical Mechanisms ◽  
Magnesium Niobate

Amorphous spherical particles of magnesium and potassium niobates were produced by homogeneous precipitation in solutions of magnesium and potassium salts, respectively, in the presence of polymeric niobium oxo-hydroxide ions. At pH 9 solids of definitive compositions were achieved and converted to crystalline powders of MgNb2O6 and KNbO3 on calcination. Chemical mechanisms for the formation and transformation of such colloidal particles are offered.

scholarly journals Some considerations on the use of the geoelectric «square» array

1996 ◽  
Vol 39 (1) ◽  
Author(s):  
F. Merlanti ◽  
M. Pavan
Keyword(s):  
Error Term ◽  
Homogeneous Medium ◽  
Archaeological Site ◽  
Point Of View ◽  
Practical Application ◽  
Linear Arrays ◽  
Relative Measurements ◽  
Square Array ◽  
Anisotropy Coefficients

The «square array» is what we may consider to be an unconventional geoelectric configuration since it is not widely used and therefore there are few examples of practical application. The purpose of this research was to verify the operating effectiveness of this configuration in terms of profile and sounding, and the significance of the set of possible measurements and derived parameters. This was also obtained by comparing the relative measurements with the most common linear arrays (Wenner, Schlumberger, tripotential). The experiment was carried out in two different zones. In the first area, corresponding to the archaeological site of Marzabotto (Bologna), the target was represented by wall remnants inserted in a substantially homogeneous medium, from an electrical point of view, and at depths that are less than those of the dimensions of the device used. At the second site, located in the valley of Landrazza (Savona), the situation was very different, with a valley section on a calcareous bedrock filled with poorly classified residual sediments. An overall analysis of the results showed that the square technique is more exhaustive than the classical linear arrangements when performing soundings. Instead, with regard to profile development, it is not as preferred since it involves a greater amount of work without generating improved information. From analysis of the experimental results, considerable doubts arose about the meaning and the use of the anisotropy coefficients and the error term as defined theoretically. These parameters turned out to be of little use with regard to the characterization of the ground anisotropy and for checking the reliability of the measurements.

scholarly journals Application of Dynamic and Static Light Scattering for Size and Shape Characterization of Small Extracellular Nanoparticles in Plasma and Ascites of Ovarian Cancer Patients

2021 ◽  
Vol 22 (23) ◽  
pp. 12946
Author(s):  
Ksenija Kogej ◽  
Darja Božič ◽  
Borut Kobal ◽  
Maruša Herzog ◽  
Katarina Černe
Keyword(s):  
Ovarian Cancer ◽  
Light Scattering ◽  
Spherical Particles ◽  
Radius Of Gyration ◽  
Non Invasive ◽  
Peritoneal Washing ◽  
Angular Dependency ◽  
Shape Characterization ◽  
Further Development

In parallel to medical treatment of ovarian cancer, methods for the early detection of cancer tumors are being sought. In this contribution, the use of non-invasive static (SLS) and dynamic light scattering (DLS) for the characterization of extracellular nanoparticles (ENPs) in body fluids of advanced serous ovarian cancer (OC) and benign gynecological pathology (BP) patients is demonstrated and critically evaluated. Samples of plasma and ascites (OC patients) or plasma, peritoneal fluid, and peritoneal washing (BP patients) were analyzed. The hydrodynamic radius (Rh) and the radius of gyration (Rg) of ENPs were calculated from the angular dependency of LS intensity for two ENP subpopulations. Rh and Rg of the predominant ENP population of OC patients were in the range 20–30 nm (diameter 40–60 nm). In thawed samples, larger particles (Rh mostly above 100 nm) were detected as well. The shape parameter ρ of both particle populations was around 1, which is typical for spherical particles with mass concentrated on the rim, as in vesicles. The Rh and Rg of ENPs in BP patients were larger than in OC patients, with ρ ≈ 1.1–2, implying a more elongated/distorted shape. These results show that SLS and DLS are promising methods for the analysis of morphological features of ENPs and have the potential to discriminate between OC and BP patients. However, further development of the methodology is required.

SIMULATION OF NONLINEAR ULTRASONIC PULSES PROPAGATING THROUGH BUBBLY LAYERS IN A LIQUID: FILTERING AND CHARACTERIZATION

2010 ◽  
Vol 18 (01) ◽  
pp. 47-68 ◽  
Author(s):  
CHRISTIAN VANHILLE ◽  
CLEOFÉ CAMPOS-POZUELO
Keyword(s):  
Homogeneous Medium ◽  
Nonlinear Effects ◽  
Nonlinear Propagation ◽  
Pressure Amplitude ◽  
Screen Effect ◽  
Nonlinear Characterization ◽  
Bubble Sizes ◽  
The Time Domain ◽  
Filter Effects

This paper deals with the nonlinear propagation of ultrasonic pulses in a homogeneous medium in which a bubbly layer is placed. The medium we use is air bubbles in water. During the propagation of a pulse, the interaction of the acoustic field and bubbles vibration is assured via the coupling of a nonlinear differential system. The solution is tracked in the time domain by means of the SNOW-BL code. In the biphasic fluid, attenuation and nonlinear effects are due to the bubbles only. The study addresses to two applications: filter effects of the layer and nonlinear characterization of liquid–gas mixtures. We study the filter effects (screen effect) a layer has for some frequency ranges present in the initial ultrasonic pulses, in the linear and nonlinear regimes, i.e. for low and high pressure amplitude. One (or several) simple layer is contemplated in numerical experiments with different bubble densities, bubble sizes, layer thicknesses, for different kinds of pulse.

scholarly journals The Synthesis and Effect of Silver Nanoparticles on the Adsorption of Cu2+ from Aqueous Solutions

2020 ◽  
Vol 10 (14) ◽  
pp. 4840
Author(s):  
Ghadah M. Al-Senani ◽  
Nada Al-Kadhi
Keyword(s):  
Aqueous Solution ◽  
Freundlich Isotherm ◽  
Spherical Particles ◽  
Convolvulus Arvensis ◽  
X Ray ◽  
Nanoparticle Surface ◽  
Before And After ◽  
Adsorption Processes ◽  
Sem Analyses

The adsorption of Cu2+ ions from an aqueous solution using AgNPs synthesized from Convolvulus arvensis leaf extract was investigated. The characterization of AgNPs was investigated before and after the adsorption of Cu2+ ions via Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) analyses. The adsorbent contained various functional groups in addition to the AgNPs, which contributed to the Cu2+ ions adsorption. The silver nanoparticle surface consisted of spherical particles and deep pores, which adsorbed numerous Cu2+ ions. The influences of dosage, pH, and contact time on adsorption of 10 and 50 mg/L Cu2+ at 298 K, and initial Cu2+ concentrations at 298 and 323 K were studied. It was found that the highest percentage of Cu2+ ions adsorbed from an aqueous solution was 98.99%; the aqueous solution had 10 mg/L of Cu2+ ions and 0.2 g of AgNPs, at pH 12 and 298 K. A pseudo-second kinetics model offered the most accurate description of the process of adsorption. The process of Cu2+ adsorption more resembled a Langmuir rather than a Freundlich isotherm model, including chemical and physical mixed adsorption (mixed adsorption) processes, and was exothermic and spontaneous.

Preparation and characterization of sub-micron spherical particles of Al2O3, SiO2 and mullite

1998 ◽  
Vol 53 (3) ◽  
pp. 247-251 ◽  
Author(s):  
P. Murugavel ◽  
M. Kalaiselvam ◽  
M.K. Renganathan ◽  
A.R. Raju
Keyword(s):  
Spherical Particles
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