Characterization of Particles Synthesized by Aerosol Processes for Various Pb:Si Molar Feed Ratios

1995 ◽  
Vol 400 ◽  
Author(s):  
Timothy M. Owens ◽  
Pratim Biswas
Keyword(s):  
Flow Reactor ◽  
Particle Morphology ◽  
High Specific Surface Area ◽  
Spherical Particles ◽  
Maximum Temperature ◽  
Lead Silicate ◽  
Lead Compounds ◽  
Large Agglomerate ◽  
Primary Particles

AbstractA detailed characterization was performed of the particles produced under various Pb:Si molar feed ratios in a flow reactor at a maximum temperature of 1000 °C. The silica particles formed in the high temperature region coagulated and only partially coalesced to form large agglomerate structures of high specific surface area. For a lead only feed, the resulting particles were hydrocerussite with small but detectable amounts of massicot. As the silica precursor was inlet in excess amounts (Pb:Si ≤ 1:12), the crystalline lead compounds disappeared and amorphous lead-silica complexes predominated. The particle morphology also changed from cylindrical, polygonal and spherical shapes to large agglomerate structures composed of several size modes of primary particles. At Pb:Si molar feed ratios of 1:12 and 1:29, the particles making up the chain-like agglomerate structure were primarily spherical with larger lead silicate spherical particles (≈ 0.5 μm) attached to the agglomerate. The lead was found to be distributed throughout the large agglomerate structures.

scholarly journals Production of L-Leucine Nanoparticles under Various Conditions Using an Aerosol Flow Reactor Method

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Anna Lähde ◽  
Janne Raula ◽  
Esko I. Kauppinen
Keyword(s):  
Vapour Deposition ◽  
Flow Reactor ◽  
Geometric Mean ◽  
Particle Morphology ◽  
Particle Method ◽  
Vapour Phase ◽  
Spherical Particles ◽  
Subsequent Growth ◽  
Aerosol Flow ◽  
Size Distribution Of Particles

We have studied the formation of L-leucine nanoparticles under various conditions using an aerosol flow reactor method. Temperatures and L-leucine concentrations for the experiments were selected to vary the saturation conditions for L-leucine in the reactor. In the two extreme cases, L-leucine is either in (i) the condensed phase (110°C) or completely in (ii) the vapour phase (200°C) for all concentrations; (iii) at the intermediate temperature (150°C), the extent of evaporation of L-leucine depends notably on the concentration, and thus partial evaporation and production of residual particles are expected. The size distribution of particles and the particle morphology varied according to formation mechanism with the geometric mean diameter of the particles between 30 nm and 210 nm. Hollow, spherical particles were obtained with the droplet-to-particle method without vaporisation of L-leucine; whereas leafy-looking particles were produced by homogeneous nucleation of supersaturated L-leucine vapour and subsequent growth by heterogeneous vapour deposition.

Characterization of Large Particles in Fumed Silica Based CMP Slurry

2010 ◽  
Vol 1249 ◽  
Author(s):  
W. Scott Rader ◽  
Timothy Holt ◽  
Kazusei Tamai
Keyword(s):  
Fumed Silica ◽  
Large Particle ◽  
Particle Morphology ◽  
Sedimentation Rates ◽  
Transmission Electron ◽  
Primary Particles ◽  
Large Particles ◽  
Small Primary ◽  
Morphological Differences

AbstractLarge particles in fumed silica dispersions were characterized by sedimentation, light scattering techniques, Transmission Electron Microscopy (TEM), and lacunarity. Applying centrifugation to fumed silica dispersions generated differences in sedimentation rates of large particles. The sedimentation rates of the large particles were affected by morphological differences and the particles remaining in the supernatant displayed buoyant behavior. The large particle morphology varied from branch like aggregates containing large primary particles to particles comprised of highly coalesced, tightly packed small primary particles. The results indicate the presence of different types of large particles in fumed silica dispersions to which conventional large particle characterization is unable to distinguish.

Cryomicroscopy of multiphase latices

1991 ◽  
Vol 49 ◽  
pp. 1060-1061
Author(s):  
O. L. Shaffer ◽  
M.S. El-Aasser ◽  
C. L. Zhao ◽  
M. A. Winnik ◽  
R. R. Shivers
Keyword(s):  
Electron Microscopy ◽  
Radiation Damage ◽  
Freeze Fracture ◽  
Particle Morphology ◽  
Second Stage ◽  
Transmission Electron ◽  
Important Approach ◽  
Carbon Coated ◽  
Preparation Techniques

Transmission electron microscopy is an important approach to the characterization of the morphology of multiphase latices. Various sample preparation techniques have been applied to multiphase latices such as OsO4, RuO4 and CsOH stains to distinguish the polymer phases or domains. Radiation damage by an electron beam of latices imbedded in ice has also been used as a technique to study particle morphology. Further studies have been developed in the use of freeze-fracture and the effect of differential radiation damage at liquid nitrogen temperatures of the latex particles embedded in ice and not embedded.Two different series of two-stage latices were prepared with (1) a poly(methyl methacrylate) (PMMA) seed and poly(styrene) (PS) second stage; (2) a PS seed and PMMA second stage. Both series have varying amounts of second-stage monomer which was added to the seed latex semicontinuously. A drop of diluted latex was placed on a 200-mesh Formvar-carbon coated copper grid.

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.

Design and Characterization of a Novel Upward Flow Reactor for the Study of High-Temperature Thermal Reduction for Solar-Driven Processes

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
H. Evan Bush ◽  
Karl-Philipp Schlichting ◽  
Robert J. Gill ◽  
Sheldon M. Jeter ◽  
Peter G. Loutzenhiser
Keyword(s):  
High Temperature ◽  
Flow Reactor ◽  
Thermal Reduction ◽  
Heat Fluxes ◽  
O2 Evolution ◽  
Transfer Model ◽  
Upward Flow ◽  
Heating Rates ◽  
Solar Simulator

The design and characterization of an upward flow reactor (UFR) coupled to a high flux solar simulator (HFSS) under vacuum is presented. The UFR was designed to rapidly heat solid samples with concentrated irradiation to temperatures greater than 1000 °C at heating rates in excess of 50 K/s. Such conditions are ideal for examining high-temperature thermal reduction kinetics of reduction/oxidation-active materials by temporally monitoring O2 evolution. A steady-state, computational fluid dynamics (CFD) model was employed in the design to minimize the formation of eddies and recirculation, and lag and dispersion were characterized through a suite of O2 tracer experiments using deconvolution and the continuously stirred tank reactors (CSTR) in series models. A transient, CFD and heat transfer model of the UFR was combined with Monte Carlo ray tracing (MCRT) to determine radiative heat fluxes on the sample from the HFSS to model spatial and temporal sample temperatures. The modeled temperatures were compared with those measured within the sample during an experiment in which Co3O4 was thermally reduced to CoO and O2. The measured temperatures within the bed were bounded by the average top and bottom modeled bed temperatures for the duration of the experiment. Small variances in the shape of the modeled versus experimental temperatures were due to contact resistance between the thermocouple and particles in the bed and changes in the spectral absorptivity and emissivity as the Co3O4 was reduced to CoO and O2.

scholarly journals Use of Electrosprayed Agave Fructans as Nanoencapsulating Hydrocolloids for Bioactives

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 868 ◽  
Author(s):  
Jorge Ramos-Hernández ◽  
Juan Ragazzo-Sánchez ◽  
Montserrat Calderón-Santoyo ◽  
Rosa Ortiz-Basurto ◽  
Cristina Prieto ◽  
...  
Keyword(s):  
Uv Light ◽  
Particle Morphology ◽  
Bioactive Compound ◽  
Processing Parameters ◽  
Degree Of Polymerization ◽  
Spherical Particles ◽  
Sem Images ◽  
High Degree ◽  
Thermal Stability Of ◽  
Β Carotene

High degree of polymerization Agave fructans (HDPAF) are presented as a novel encapsulating material. Electrospraying coating (EC) was selected as the encapsulation technique and β-carotene as the model bioactive compound. For direct electrospraying, two encapsulation methodologies (solution and emulsion) were proposed to find the formulation which provided a suitable particle morphology and an adequate concentration of β-carotene encapsulated in the particles to provide a protective effect of β-carotene by the nanocapsules. Scanning electron microscopy (SEM) images showed spherical particles with sizes ranging from 440 nm to 880 nm depending on the concentration of HDPAF and processing parameters. FTIR analysis confirmed the interaction and encapsulation of β-carotene with HDPAF. The thermal stability of β-carotene encapsulated in HDPAF was evidenced by thermogravimetric analysis (TGA). The study showed that β-carotene encapsulated in HDPAF by the EC method remained stable for up to 50 h of exposure to ultraviolet (UV) light. Therefore, HDPAF is a viable option to formulate nanocapsules as a new encapsulating material. In addition, EC allowed for increases in the ratio of β-carotene:polymer, as well as its photostability.

scholarly journals Thermal and structural characterization of the vitreous samples in the SiO2 - PbO - Na2O system

2006 ◽  
pp. 89-95 ◽  
Author(s):  
Catalina Mocioiu ◽  
Georgeta Jitianu ◽  
Maria Zaharescu
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Infrared Spectroscopy ◽  
Silicate Glasses ◽  
Lead Silicate ◽  
High Chemical ◽  
Nuclear Techniques ◽  
Infrared Data

Lead-containing glasses have been used from the ancient time. Recently, due to the possible application in optics, electronics, nuclear techniques, wastes inactivation. the interest in these types of glasses has been renewed. For lead waste inactivation, glasses with high amount of PbO in the composition are required, those exhibiting at the same time a high chemical and thermal stability. Thermal behavior of lead-silicate glasses was examined by differential thermal analysis (DTA). Infrared spectroscopy was used to investigate the structure of the glasses. The spectra were interpreted in terms of the structures of silicate group by comparison with the spectra of other silicate crystals. The DTA and infrared data were correlated with the chemical stability tests.

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.

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