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Particle Charge (particle + charge)

Distribution by Scientific Domains

Polymers and Materials Science	40%

Selected Abstracts

Sedimentation behaviour and turbidity of carrot juices in relation to the characteristics of their cloud particles

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2003
Martin Reiter
Abstract The cloud stability of carrot juices was investigated using physical methods. In contrast to cloudy juices from fruits or other vegetables described so far, complete clarification of juice samples could not be achieved even after ultracentrifugation. Since the density of one particle fraction was almost equal to that of the continuous phase, this fraction was resistant to sedimentation by centrifugal forces up to 60 600 × g in an 8° Brix carrot juice. Cloud stability problems of carrot juices, therefore, are usually associated with bottom sediment formation, but not with visible loss of turbidity. Particle size and density were shown to be decisive for suspension stability, whilst both particle charge and serum viscosity did not show any effect on cloud stability. The reasons for the exceptional stability of the suspended particles are discussed. Based on three particle fractions, a new physical concept could be deduced according to particle size and density explaining the extraordinary suspension stability of carrot juices. Copyright © 2003 Society of Chemical Industry [source]

Uptake Mechanism of Oppositely Charged Fluorescent Nanoparticles in HeLa Cells

MACROMOLECULAR BIOSCIENCE, Issue 12 2008
Julia Dausend
Abstract The endocytotic mechanisms involved in the uptake of charged polystyrene nanoparticles into HeLa cells were investigated. Uptake experiments were done in the presence or absence of drugs known to inhibit various factors in endocytosis. Independent of the particle charge, endocytosis is highly dependent on dynamin, F-actin, and tyrosine-specific protein kinases, which suggests a dynamin-dependent and lipid raft-dependent mechanism. However, cholesterol depletion did not hinder particle uptake. Regarding positively charged particles, macropinocytosis, the microtubule network, and cyclooxygenases are also involved. The clathrin-dependent pathway plays a minor role. [source]

Electrostatic Charge Measurement and Charge Neutralization of Fine Aerosol Particles during the Generation Process

PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 5 2005
Chuen-Jinn Tsai
Abstract An aerosol charge analyzer has been constructed to measure the charge distribution of NaCl particles generated in the laboratory. A radioactive electrostatic charge neutralizer utilizing Po-210 was used to neutralize the electrostatic charge of the particles. The atomization technique was used to generate NaCl particles with diameters of 0.2 to 0.8 ,m, while the evaporation and condensation method was adopted to generate particles of 0.01 to 0.2 ,m in diameter. The experimental data demonstrates that the absolute average particle charge depends on the particle diameter, and is higher than that calculated by the Boltzmann charge equilibrium for particles within the range of 0.2 to 0.8 ,m. The charge increases with decreasing NaCl concentration. When these particles are neutralized using the Po-210 neutralizer, it is found that the electrostatic charge reaches the Boltzmann charge equilibrium. For 0.01 to 0.2 ,m NaCl particles generated using the evaporation and condensation method, test results show that the absolute average particle charge is higher than that calculated by the Boltzmann charge equilibrium for particles larger than 0.03 to 0.05 ,m in diameter, while it is lower than that predicted by the Fuchs theory [1], for particles smaller than 0.03 to 0.05 ,m. However, after charge neutralization, particles with diameter above 0.05 ,m reach the Boltzmann charge equilibrium condition, and the charges for particles with diameters of 0.010 to 0.05 ,m, agree well with Fuchs' theory. [source]

2261: Development and evaluation of PLGA nanoparticles with cyclosporine and the inclusion of HP,CD for ocular use

ACTA OPHTHALMOLOGICA, Issue 2010
K HERMANS
Ocular delivery of peptides requires new concepts in order to optimize the bioavailability and its therapeutic effect. The first peptide selected in present research project is Cyclosporine A (CyA) used in the treatment of the dry eye syndrome and against corneal graft rejection. The aim of the project is the development of nanoparticles with physicochemical properties for a suitable and prolonged release of CyA, using a factorial design. These drug delivery systems will be produced employing PLGA using the emulsification solvent evaporation method. Positively charged polymers as chitosan or Eudragit® will be incorporated to obtain nanoparticles with a positive particle charge. Electrostatic interactions with the negatively charged mucins lead to a prolonged residence time at the precorneal area. Nanoparticles will be evaluated on zeta potential, particle size and their in vitro drug release properties. CyA and CyA complexed with HP,CD will be compared. The most suitable preparations will be selected in a next phase of the project for an in vivo study using an animal model. [source]

Computationally efficient expressions for the collision efficiency between electrically charged aerosol particles and cloud droplets

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 618 2006
S. N. Tripathi
Abstract A multiple factor parametrization is described to permit the efficient calculation of collision efficiency (E) between electrically charged aerosol particles and neutral cloud droplets in numerical models of cloud and climate. The four-parameter representation summarizes the results obtained from a detailed microphysical model ofE, which accounts for the different forces acting on the aerosol in the path of falling cloud droplets. The parametrization's range of validity is for aerosol particle radii of 0.4 to 10 ,m, aerosol particle densities of 1 to 2.0 g cm,3, aerosol particle charges from neutral to 100 elementary charges and drop radii from 18.55 to 142 , m. The parametrization yields values ofE well within an order of magnitude of the detailed model's values, from a dataset of 3978E values. Of these values 95% have modelled to parametrized ratios between 0.5 and 1.5 for aerosol particle sizes ranging between 0.4 and 2.0 , m, and about 96% in the second size range. This parametrization speeds up the calculation ofE by a factor of ,103 compared with the original microphysical model, permitting the inclusion of electric charge effects in numerical cloud and climate models. Copyright © 2006 Royal Meteorological Society [source]