Characterization of activated sludge flocs structure

1997 ◽  
Vol 36 (4) ◽  
pp. 313-320 ◽  
Author(s):  
D. Snidaro ◽  
F. Zartarian ◽  
F. Jorand ◽  
J.-Y. Bottero ◽  
J.-C. Block ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fractal Dimension ◽  
Activated Sludge ◽  
Size Distribution ◽  
Distribution Analysis ◽  
Fractal Object ◽  
Floc Structure ◽  
Transmission Electron ◽  
Investigation Methods

Activated sludge is the most widely used process for wastewater treatment. However basic properties such as floc structure or settling properties, still remain unknown. In order to describe activated sludge floc structure, four investigation methods were used: (i) size distribution analysis associated with sonication, (ii) transmission electron microscopy (iii) laser scanning confocal microscopy and fractal dimension analysis, and (iv) three dimensional modelling. The evolution of floc size distribution in dispersed samples was used to build a model of floc showing that the predominating microflocs (125 μm) are formed from 13 μm aggregates, which are made up of smaller particles (2.5 μm). By transmission electron microscopy it was assumed that the 2.5 μm sub-units could correspond to microorganisms and that exopolymers form a gel-like matrix which holds the structure of the aggregates together. The microfloc (13 μm) structure was investigated by confocal scanning light microscopy and image processing. The analysis of the mass distribution pointed out that the microfloc is a fractal object (fractal dimension around 3). The total number of cells in these aggregates was found to be 2n number. These two results suggest that division of microorganisms explained the formation of 13 μm units which are microcolonies. A mass fractal dimension 2.5 ± 0.15 was measured for the microfloc. Its external surface was reconstructed by using interpolating software (GOCAD). It appeared that the surface is also a fractal object with a dimension 2.3 ± 0.1. According to the fractal theory, it seems that diffusion limited aggregation via monomer-cluster collision is the mechanism which describes the formation of macroflocs.

Nanocrystal size distribution analysis from transmission electron microscopy images

Nanoscale ◽  
2015 ◽  
Vol 7 (48) ◽  
pp. 20593-20606 ◽  
Author(s):  
Martijn van Sebille ◽  
Laurens J. P. van der Maaten ◽  
Ling Xie ◽  
Karol Jarolimek ◽  
Rudi Santbergen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Size Distribution ◽  
Nanocrystal Size ◽  
Distribution Analysis ◽  
Transmission Electron ◽  
Microscopy Images

We propose a method to quickly detect and measure the nanocrystal size distribution from TEM images.

scholarly journals Major Factors Influencing the Size Distribution Analysis of Cellulose Nanocrystals Imaged in Transmission Electron Microscopy

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3318
Author(s):  
Hui Qian
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Size Distribution ◽  
Cross Section ◽  
Cellulose Nanocrystals ◽  
Staining Method ◽  
Distribution Analysis ◽  
Size Measurement ◽  
Transmission Electron ◽  
Coffee Ring Effect

Size distributions of cellulose nanocrystals (CNCs), extracted from softwood pulp via strong sulfuric acid hydrolysis, exhibit large variability when analyzed from transmission electron microscopy (TEM) images. In this article, the causes of this variability are studied and discussed. In order to obtain results comparable with those reported, a reference material of CNCs (CNCD-1) was used to evaluate size distribution. CNC TEM specimens were prepared as-stained and dried with a rapid-flushing staining method or hydrated and embedded in vitreous ice with the plunge-freezing method. Several sets of bright-field TEM (BF-TEM), annular dark-field scanning TEM (ADF-STEM) and cryogenic-TEM (cryo-TEM) images were acquired for size distribution analysis to study the contributing factors. The rapid-flushing staining method was found to be the most effective for contrast enhancement of CNCs, not only revealing the helical structure of single CNCs but also resolving the laterally jointed CNCs. During TEM specimen preparation, CNCs were fractionated on TEM grids driven by the coffee-ring effect, as observed from contrast variation of CNCs with a stain-depth gradient. From the edge to the center of the TEM grids, the width of CNCs increases, while the aspect ratio (length to width) decreases. This fractionated dispersion of CNCs suggests that images taken near the center of a droplet would give a larger mean width. In addition to particle fractionation driven by the coffee-ring effect, the arrangement and orientation of CNC particles on the substrate significantly affect the size measurement when CNC aggregation cannot be resolved in images. The coexistence of asymmetric cross-section CNC particles introduces a large variation in size measurement, as TEM images of CNCs are mixed projections of the width and height of particles. As a demonstration of how this contributes to inflated size measurement, twisted CNC particles, rectangular cross-section particles and end-to-end jointed CNCs were revealed in reconstructed three-dimensional (3D) micrographs by electron tomography (ET).

scholarly journals The Domain and Microstructure of Resin-Bonded Magnets

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2849
Author(s):  
Marcin Jan Dośpiał
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Size Distribution ◽  
Domain Structure ◽  
Grain Size Distribution ◽  
Exchange Interactions ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Scanning Electron

This paper presents domain and structure studies of bonded magnets made from nanocrystalline Nd-(Fe, Co)-B powder. The structure studies were investigated using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Mössbauer spectroscopy and X-ray diffractometry. On the basis of performed qualitative and quantitative phase composition studies, it was found that investigated alloy was mainly composed of Nd2(Fe-Co)14B hard magnetic phase (98 vol%) and a small amount of Nd1.1Fe4B4 paramagnetic phase (2 vol%). The best fit of grain size distribution was achieved for the lognormal function. The mean grain size determined from transmission electron microscopy (TEM) images on the basis of grain size distribution and diffraction pattern using the Bragg equation was about ≈130 nm. HRTEM images showed that over-stoichiometric Nd was mainly distributed on the grain boundaries as a thin amorphous border of 2 nm in width. The domain structure was investigated using a scanning electron microscope and metallographic light microscope, respectively, by Bitter and Kerr methods, and by magnetic force microscopy. Domain structure studies revealed that the observed domain structure had a labyrinth shape, which is typically observed in magnets, where strong exchange interactions between grains are present. The analysis of the domain structure in different states of magnetization revealed the dynamics of the reversal magnetization process.

Synthesis Route towards Fine and Monodisperse Ni Nanoparticles via Hot-Injection Approach

2013 ◽  
Vol 393 ◽  
pp. 146-151 ◽  
Author(s):  
N.R. Nik Roselina ◽  
Aziz Azizan ◽  
Koay Mei Hyie ◽  
C.M. Mardziah ◽  
Salmiah Kasolang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Size Distribution ◽  
Reaction Rate ◽  
Fine Particles ◽  
Synthesis Temperature ◽  
Ni Nanoparticles ◽  
One Pot ◽  
Transmission Electron ◽  
Hot Injection

Manipulation of adding sequences have been found to influence the reaction rate, thus made it easier to produced controllable Ni nanoparticles. Hot-injection approach shown capability to significantly reduce the production time of Ni nanoparticles compared to the conventional one-pot synthesis. With minor modification on conventional polyol method, narrow, monodispersed and highly yield spherical nickel (Ni) nanoparticles were successfully produced at synthesis temperature of 60°C. Three mixing methods were investigated to study its efficiency towards producing rapid and narrower size distribution of Ni nanoparticles. Reduction processes were proposed each of the method. As-synthesized Ni nanoparticles were characterized with Transmission Electron Microscopy (TEM), Scanning Transmission Electron Microscopy (STEM) and Fourier transform infrared spectroscopy (FTIR) to analyze the size, morphology and interaction of reactants. Fine particles size distribution revealed that when hydrazine was first heated, reaction rate improved tremendously.

Transmission electron microscopy of intracellular particles of polyethylene from joint replacement prostheses: size distribution and cellular response

Biomaterials ◽  
2001 ◽  
Vol 22 (21) ◽  
pp. 2835-2842 ◽  
Author(s):  
Eric B Benz ◽  
Micheline Federman ◽  
John J Godleski ◽  
Benjamin E Bierbaum ◽  
Thomas S Thornhill ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Size Distribution ◽  
Joint Replacement ◽  
Cellular Response ◽  
Transmission Electron

Quality and Reliability Assurance of Semiconductor Devices through Transmission Electron Microscopy

1985 ◽  
Vol 62 ◽  
Author(s):  
R. F. Pinizzotto ◽  
F. Y. Clark ◽  
M. L. Jarvis
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Integrated Circuits ◽  
Thickness Measurement ◽  
Distribution Analysis ◽  
Characterization Methods ◽  
Additional Information ◽  
Silicide Layer ◽  
Transmission Electron ◽  
Quality And Reliability

ABSTRACTModern methods of sample preparation have made it possible to analyze complete, packaged integrated circuits by transmission electron microscopy. TEM has two unique capabilities that cannot be matched by other characterization methods: 1) it is a direct crystallographic probe and 2) it has excellent spatial resolution, 0.2 nm. Small personal computers can be used to translate the micrographic data into statistical information that can be analyzed by non-TEM trained engineers. The data can also be stored in a MICROSTRUCTURAL DATABANK. The experimental data is automatically compared by the computer with previously established criteria. This methodology generates additional information that is used for quality and reliability assurance testing of integrated circuits. The method is applicable to devices that are removed from electronic systems after field operation, as well as to devices that have been lifetime tested. Two examples are described and discussed: aluminum grain size distribution analysis and silicide layer thickness measurement.

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