scholarly journals On electrical effects due to sound waves in colloidal suspensions

1951 ◽  
Vol 207 (1090) ◽  
pp. 329-342 ◽  
Keyword(s):  
Double Layer ◽  
Colloidal Particles ◽  
Wave Train ◽  
Wave Length ◽  
Colloidal Suspensions ◽  
Exact Expression ◽  
Particle Radius ◽  
Potential Difference ◽  
Sound Waves ◽  
Leading Term

In this paper, the electrical effects accompanying the propagation of sound waves through a suspension of spherical colloidal particles in an electrolyte are examined. It is shown that, for charged colloidal particles, differences of potential arise between different points in the wave train. A general method is given for obtaining the amplitude of the potential difference in the case when the thickness of the double-layer surrounding the particles is small compared with the particle radius, as a power series in the zeta-potential and the leading term in this series is evaluated, so that the results will be adequate for zeta-potentials which are not too large. An exact expression is obtained for the case when the thickness of the double-layer is very much greater than the particle radius but still much less than the mean separation. An attempt is also made to estimate the effect for intermediate values of the double-layer thickness. The amplitude of the potential difference decreases with increasing concentration of electrolyte and, when measured between points a half-wave-length apart, is substantially independent of the frequency of the sound waves, except at very high frequencies. The results are compared with the experimental data.

Aggregation of binary colloidal suspensions on attractive walls

2016 ◽  
Vol 18 (4) ◽  
pp. 3073-3079 ◽  
Author(s):  
Aleena Laganapan ◽  
Davide Bochicchio ◽  
Marguerite Bienia ◽  
Arnaud Videcoq ◽  
Riccardo Ferrando
Keyword(s):  
Solid Surface ◽  
Colloidal Particles ◽  
Biological Systems ◽  
Colloidal Suspensions ◽  
Fundamental Importance

The adsorption of colloidal particles from a suspension on a solid surface is of fundamental importance to many physical and biological systems.

scholarly journals Electric double layer and electrokinetic potential of pectic macromolecules in sugar beet

2008 ◽  
pp. 21-28
Author(s):  
Tatjana Kuljanin ◽  
Ljubinko Levic ◽  
Nevena Misljenovic ◽  
Gordana Koprivica
Keyword(s):  
Sugar Beet ◽  
Double Layer ◽  
Electric Double Layer ◽  
Colloidal Particles ◽  
Colloidal Particle ◽  
Electrokinetic Potential ◽  
Shear Plane ◽  
Colloidal System ◽  
Cu Ions ◽  
Measurable Property

Electrokinetic potential is an important property of colloidal particles and, regarding the fact that it is a well defined and easily measurable property, it is considered to be a permanent characteristic of a particular colloidal system. In fact, it is a measure of electrokinetic charge that surrounds the colloidal particle in a solution and is in direct proportion with the mobility of particles in an electric field. Gouy-Chapman-Stern-Graham's model of electric double layer was adopted and it was proven experimentally that the addition of Cu++ ions to sugar beet pectin caused a reduction in the negative electrokinetic potential proportional to the increase of Cu++ concentration. Higher Cu++ concentrations increased the proportion of cation specific adsorption (Cu++ and H+) with regard to electrostatic Coulombic forces. Consequently, there is a shift in the shear plane between the fixed and diffuse layers directed towards the diffuse layer, i.e. towards its compression and decrease in the electrokinetic potential or even charge inversion of pectin macromolecules.

scholarly journals BREAKWATER ARMOR DISPLACEMENT THRESHOLDS: A POSSIBLE CORRELATION WITH CUMULATIVE WAVE ENERGY

1984 ◽  
Vol 1 (19) ◽  
pp. 186
Author(s):  
Daniel L. Behnke ◽  
Frederic Raichlen
Keyword(s):  
Wave Energy ◽  
Wave Train ◽  
Wave Length ◽  
Simple Wave ◽  
Wave Theory ◽  
Irregular Waves ◽  
Reconstruction Technique ◽  
Regular Wave ◽  
Regular Waves ◽  
Three Dimensional Model

An extensive program of stability experiments in a highly detailed three-dimensional model has recently been completed to define a reconstruction technique for a damaged breakwater (Lillevang, Raichlen, Cox, and Behnke, 1984). Tests were conducted with both regular waves and irregular waves from various directions incident upon the breakwater. In comparison of the results of the regular wave tests to those of the irregular wave tests, a relation appeared to exist between breakwater damage and the accumulated energy to which the structure had been exposed. The energy delivered per wave is defined, as an approximation, as relating to the product of H2 and L, where H is the significant height of a train of irregular waves and L is the wave length at a selected depth, calculated according to small amplitude wave theory using a wave period corresponding to the peak energy of the spectrum. As applied in regular wave testing, H is the uniform wave height and L is that associated with the period of the simple wave train. The damage in the model due to regular waves and that caused by irregular waves has been related through the use of the cumulative wave energy contained in those waves which have an energy greater than a threshold value for the breakwater.

The primary electroviscous effect in a suspension of spheres with thin double layers

1983 ◽  
Vol 132 ◽  
pp. 337-347 ◽  
Author(s):  
E. J. Hinch ◽  
J. D. Sherwood
Keyword(s):  
Layer Thickness ◽  
Double Layer ◽  
High Surface ◽  
Particle Radius ◽  
Double Layers ◽  
Asymptotic Results ◽  
Electroviscous Effect ◽  
Surface Potentials ◽  
Double Layer Thickness

We study the primary electroviscous effect in a suspension of spheres when the double layer thickness κ−1 is small compared with the particle radius a. The case of a 1–1 symmetric electrolyte is examined using the methods of Dukhin & coworkers (1974), whilst the asymmetric electrolyte is studied along lines similar to those of O'Brien (1983). Sherwood's (1980) asymptotic results for high surface potentials and high Hartmann numbers are extended and complemented.

scholarly journals Directional freezing of binary colloidal suspensions: a model for size fractionation of graphene oxide

Soft Matter ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 243-251 ◽  
Author(s):  
Xin Xu ◽  
Luofu Liu ◽  
Hongya Geng ◽  
Jianjun Wang ◽  
Jiajia Zhou ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Theoretical Model ◽  
Colloidal Particles ◽  
Colloidal Suspensions ◽  
Size Fractionation ◽  
Preferential Adsorption ◽  
Directional Freezing ◽  
Ice Phase

A theoretical model of a binary colloid suspension was developed by incorporating both the moving freezing boundary and the preferential adsorption of colloidal particles to the ice phase.

DIFFRACTIVE REFLECTION AND SCATTERING OF ULTRASONIC WAVES. THEIR INFLUENCE ON TORSION-PENDULUM MEASUREMENTS OF SOUND INTENSITY

1930 ◽  
Vol 3 (6) ◽  
pp. 491-509 ◽  
Author(s):  
R. W. Boyle ◽  
J. F. Lehmann
Keyword(s):  
Wave Train ◽  
Sound Intensity ◽  
Ultrasonic Waves ◽  
Special Importance ◽  
Torsion Pendulum ◽  
Sound Waves ◽  
Diffractive Scattering ◽  
Light Waves ◽  
Small Obstacle ◽  
Diffractive Reflection

Light waves are too short and ordinary sound waves generally too long to permit experimental work on diffraction and scattering by a single small obstacle. An opportunity for such work however is presented in the case of ultrasonic waves.This paper describes an experimental investigation on the factors which determine the diffractive reflection and scattering of an ultrasonic wave train by plane circular opaque discs, and discusses the results. These are of special importance in the measurement of sound energy intensity by the torsion-pendulum method, for such measurements should always be corrected to allow for the effect of diffractive scattering of the energy by the measuring-pendulum vane. The correction factor will depend on the size and form of the pendula vanes employed and for circular vanes can be obtained directly from such curves as are shown in this paper as results of the investigation.

A MEASUREMENT OF ULTRASONIC ATTENUATION COEFFICIENT BY FREQUENCY RESPONSE IN STEELS WITH DIFFERENT GRAIN SIZES

2003 ◽  
Vol 26 (4) ◽  
pp. 389-402
Author(s):  
Kyung-Cho Kim
Keyword(s):  
Frequency Response ◽  
Attenuation Coefficient ◽  
Evaluation Method ◽  
Ultrasonic Attenuation ◽  
Wave Length ◽  
Structural Behavior ◽  
Response Property ◽  
Sound Waves ◽  
Grain Sizes ◽  
Plate Specimen

A new evaluation method of ultrasonic attenuation in materials is proposed based on the frequency response property of the material evaluated by employing the sound impulse of a wide frequency band. Borrowing from ordinary system theory, the material to be tested is considered to have a characteristic impulse response, representing its micro-structural non-uniformities and thus resulting in the sound attenuation of the material. The concept is resumed as an attenuation system that simulates the material’s micro-structural behavior. Experimental results on a series of specimens, having different grain sizes but all made of a single austenitic stainless steel, showed that the attenuation could properly be evaluated from a single bottom echo in a plate specimen. The attenuation coefficient α, was corrlated in this case to the grain size, D, by the equation, αD=H(πD/λ)n, where λ is wave length and H and n are constants. It was also shown that the micro structural change of materials could be evaluated by the energy loss of sound waves passing through the attenuation systems.

Liquid Crystal Behavior of V2O5·nH2O Gels

1998 ◽  
Vol 547 ◽  
Author(s):  
J. Livage ◽  
P. Davidson ◽  
X. Commeinhes ◽  
O. Pelletier
Keyword(s):  
Liquid Crystal ◽  
Vanadium Pentoxide ◽  
Colloidal Particles ◽  
Organic Molecules ◽  
Polarized Light ◽  
Colloidal Suspensions ◽  
Acid Dissociation ◽  
Polymeric Particles ◽  
Nematic Phases ◽  
Electrostatic Repulsions

AbstractMost liquid crystals are made of organic molecules, very few of them are based on mineral compounds. Vanadium pentoxide gels and sols have been shown to give mesophases. They are made of ribbon-like polymeric particles of vanadium pentoxide dispersed in water. Ansitropic xerogel layers are formed when these gels are deposited and dried onto flat substrates. Dehydration is reversible and fluid phases are again obtained via a swelling process when water is added to the xerogel.When observed by polarized light microscopy, colloidal suspensions of V2O5 ribbons display defects typical of lyotropic nematic phases. Dilute nematic suspensions can even be oriented by applying a magnetic field of about 0.5 Tesla. Such a liquid crystal behavior is mainly due to the highly anisotropic shape of vanadium oxide colloidal particles. Acid dissociation at the oxide/water interface gives rise to surface electrical charges and electrostatic repulsions should also be responsible for the stabilization of the nematic phase.

scholarly journals On the problem of the electrified disc

1947 ◽  
Vol 8 (1) ◽  
pp. 14-19 ◽  
Author(s):  
E. T. Copson
Keyword(s):  
External Field ◽  
Gravitational Potential ◽  
Electrostatic Field ◽  
Surface Density ◽  
Wave Length ◽  
Circular Disc ◽  
Sound Waves ◽  
Total Potential ◽  
Induced Charge ◽  
Lord Kelvin

When a perfectly conducting uniform thin circular disc is kept at a potential V0 in an external electrostatic field of potential Φ, electric charge is induced on the surface of the disc; the problem is to find the surface-density σ of this induced charge and its potential V so that the total potential V + Φ has the constant value V0 on the surface of the disc. This problem was first discussed by Green in 1832, and the solution in the case when there is no external field was deduced by Lord Kelvin from the known formula for the gravitational potential of an elliptic homoeoid. The problem is still of interest since similar ideas occur in the theory of diffraction by a circular disc and in the theory of the generation of sound waves by a vibrating disc when the wave-length is large compared with the radius of the disc.

scholarly journals THE ELECTRICAL CONDUCTANCE OF SUSPENSIONS OF ELLIPSOIDS AND ITS RELATION TO THE STUDY OF AVIAN ERYTHROCYTES

1940 ◽  
Vol 23 (6) ◽  
pp. 753-771 ◽  
Author(s):  
Sidney Velick ◽  
Manuel Gorin
Keyword(s):  
Electrical Resistance ◽  
Colloidal Particles ◽  
Electrical Conductance ◽  
Colloidal Suspensions ◽  
Optical Methods ◽  
Flow Cells ◽  
Flow Method ◽  
Avian Erythrocytes

1. The theory of electrical conductance of colloidal suspensions has been extended to cover the case of ellipsoids with three axes different. 2. The results have been applied to suspensions of ellipsoidal erythrocytes of birds. 3. It has been shown that fluctuations in electrical resistance of suspensions of erythrocytes after stirring are due to streaming orientation of the cells. 4. The theory has been extended to cover four cases of orientation and tested experimentally in specially designed flow cells by electrical and optical methods. 5. Application of the flow method to the study of the shape of colloidal particles is discussed.

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