Search results for "Particle-Size"

Inverse task for evaluation of particle size distribution of polydisperse magnetic fluids

2010

AbstractThe method of inverse task was used to analyze three different physical phenomena. The particle size distributions were reconstructed from the magnetization curve, dynamic light scattering and magnetic birefringence relaxation data. The results thus obtained for one real magnetic fluid sample are different; they characterize the physical nature of the phenomena. All three methods may be used to determine intrinsic sample properties.

Do organics contribute to small particle formation in the Amazonian upper troposphere?

2008

3-D cloud-resolving model simulations including explicit aerosol physics and chemistry are compared with observations of upper tropospheric (12 km) aerosol size distributions over the Amazon Basin. ...

Plasmonic Focusing Reduces Ensemble Linewidth

2012

In this chapter I present an effect the coating of gold nanorods with a silver shell is evocating: a reduction of the ensemble plasmon linewidth by changing the plasmon-shape relation, which connects the particle shape with its plasmon resonance wavelength. This change, we term “plasmonic focusing” (Sect. 10.2), leads to less variation of resonance wavelengths for the same particle size distribution. Section 10.3 explains the effect of increasing single particle linewidth during the coating process, which is therefore not the reason for the observed ensemble linewidth decrease. This is rather a result from a change in the plasmon-shape relation explained in Sect. 10.4. Using a simple model,…

Surface structure determination by SEM image processing and electrochemical impedance of graphite+polyethylene composite electrodes

2004

Abstract The electrochemical impedance behaviour of heterogeneous or/and rough electrodes has usually been associated with some geometrical parameters of the surface structure or to a statistical description of the surface properties. An experimental method for sample preparation of graphite + polyethylene composite electrodes based on plasma etching is proposed. After plasma etching, the statistical properties of the electrode, such as the graphite particle size distribution and fractional coverage are measured from scanning electron microscopy pictures using image processing software. The statistical information obtained for the surface is combined with impedance equations of independent …

The Impact of Grain Size Composition and Organic Matter Content on Magnetic Susceptibility of Anthropogenically Transformed Bottom Sediments, as Exem…

2017

The article presents the results of an analysis of the surface layer of bottom sediments in the naval harbour in Hel. During field work conducted in June 2013, 54 sediment samples were collected. The aim of the study was to examine magnetic susceptibility of harbour sediment as a parameter determining the degree of anthropopressure. As part of laboratory tests, grain size analysis was performed in order to determine organic matter content and magnetic susceptibility of the sediment. The study also measured the impact of environmental factors on fluctuations in the other studied parameters. The results demonstrate increased dynamics of sedimentary environment in the open part of the naval ha…

Novel hydrogels based on a polyasparthydrazide. Synthesis and characterization

2000

α,β-polyasparthydrazide (PAHy), a synthetic water-soluble biocompatible polymer, was chemically crosslinked with ethyleneglycol diglycidylether (EGDGE), in order to obtain water swellable microparticies. These were characterized by means of FT-IR spectrophotometry and by means of particle size distribution analysis. The mean pore size of the prepared gels as various crosslinking ratios and the fractal dimensions were determined by light scattering measurements. Swelling measurements gave evidence of the high affinity of PAHy-EGDGE microparticles towards aqueous media at different pH values. The physical state of the prepared networks was evaluated by means of X-rays diffractometry and therm…

Nanoparticles Size Distribution Assessment During Early Synthesis Stages

2021

Nanotechnology, an innovative field of material science, designs and produces nanostructures materials with unique properties that make them suited for various bioengineering applications. The shape and the dimension are the main variables depending on the method of synthesis or chemical precursors. Silver nanoparticles obtained through chemical synthesis exhibit as strong antibacterial effect if their size lays in a well-defined range. However, a small size of such particles, in the range of nanometers to several tens of nanometers, requires specific techniques as Dynamic Light Scattering or Transmission Electron Microscopy, both being affected by certain assumptions or by the high cost an…

2015

Abstract. This paper presents results from the "INUIT-JFJ/CLACE 2013" field campaign at the high alpine research station Jungfraujoch in January/February 2013. The chemical composition of ice particle residuals (IPR) in a size diameter range of 200–900 nm was measured in orographic, convective and non-convective clouds with a single particle mass spectrometer (ALABAMA) under ambient conditions characterized by temperatures between −28 and −4 °C and wind speed from 0.1 to 21 km h−1. Additionally, background aerosol particles in cloud free air were investigated. The IPR were sampled from mixed-phase clouds with two inlets which selectively extract small ice crystals in-cloud, namely the Count…

Critical assessment of particle size analysis of porous silica microbead high-performance liquid chromatographic packings by photosedimentation

1979

Abstract Particle size analysis of commercial spherical silica packings of graduated pore size by means of photosedimentation (PS) is critically examined and compared to results obtained by microscopy. To avoid particle fractionation, the suspension prepared for PS measurements should be subjected to gentle ultrasonic treatment. For computing the particle size distribution, the effective density of solvent-filled porous particles has to be inserted into the Stokes equation. Reproducibility of d p , estimated by PS is found to be largely dependent upon the accuracy of the specific pore volume determination. Satisfactory agreement of data between PS and microscopy is obtained for all products…

Predicting the equilibrium bed slope in natural streams using a stochastic model for incipient sediment motion

2011

In this paper, a method to predict the equilibrium bed slope in natural streams based on the incipient motion criterion is proposed. The method is based on the criterion suggested by Gessler to simulate the grain size distribution of the armour coat using the concept of critical shear stress of a sediment mixture. In particular, a different expression of the probability for a single particle size to be part of the armour coat is firstly proposed; then, a simple two-steps criterion is suggested to estimate the safety factor required by the proposed approach. The method is applied in three different Italian regions (Calabria, Basilicata, and Tuscany) and required several field campaigns invol…