112,104 research outputs found
Dielectric behavior of oblate spheroidal particles: Application to erythrocytes suspensions
We have investigated the effect of particle shape on the eletrorotation (ER)
spectrum of living cells suspensions. In particular, we consider coated oblate
spheroidal particles and present a theoretical study of ER based on the
spectral representation theory. Analytic expressions for the characteristic
frequency as well as the dispersion strength can be obtained, thus simplifying
the fitting of experimental data on oblate spheroidal cells that abound in the
literature. From the theoretical analysis, we find that the cell shape, coating
as well as material parameters can change the ER spectrum. We demonstrate good
agreement between our theoretical predictions and experimental data on human
erthrocytes suspensions.Comment: RevTex; 5 eps figure
Many-body dipole-induced dipole model for electrorheological fluids
Theoretical investigations on electrorheological (ER) fluids usually rely on
computer simulations. An initial approach for these studies would be the
point-dipole (PD) approximation, which is known to err considerably when the
particles approach and finally touch due to many-body and multipolar
interactions. Thus various work attempted to go beyond the PD model. Being
beyond the PD model, previous attempts have been restricted to either
local-field effects only or multipolar effects only, but not both. For
instance, we recently proposed a dipole-induced-dipole (DID) model which is
shown to be both more accurate than the PD model and easy to use. This work is
necessary because the many-body (local-field) effect is included to put forth
the many-body DID model. The results show that the multipolar interactions can
indeed be dominant over the dipole interaction, while the local-field effect
may yield an important correction.Comment: RevTeX, 3 eps figure
Giant enhanced optical nonlinearity of colloidal nanocrystals with a graded-index host
The effective linear and third-order nonlinear optical properties of metallic
colloidal crystal immersed in a graded-index host fluid are investigated
theoretically. The local electric fields are extracted self-consistently based
on the layer-to-layer interactions, which are readily given by the Lekner
summation method. The resultant optical absorption and nonlinearity enhancement
show a series of sharp peaks, which merge in a broadened resonant band. The
sharp peaks become a continuous band for increasing packing density and number
of layers. We believe that the sharp peaks arise from the in-plane dipolar
interactions and the surface plasmon resonance, whereas the continuous band is
due to the presence of the gradient in the host refractive index. These results
have not been observed in homogeneous and randomly-dispersed colloids, and thus
would be of great interest in optical nanomaterial engineering.Comment: Submitted to Applied Physics Letter
Generalized linear isotherm regularity equation of state applied to metals
A three-parameter equation of state (EOS) without physically incorrect
oscillations is proposed based on the generalized Lennard-Jones (GLJ) potential
and the approach in developing linear isotherm regularity (LIR) EOS of Parsafar
and Mason [J. Phys. Chem., 1994, 49, 3049]. The proposed (GLIR) EOS can include
the LIR EOS therein as a special case. The three-parameter GLIR, Parsafar and
Mason (PM) [Phys. Rev. B, 1994, 49, 3049], Shanker, Singh and Kushwah (SSK)
[Physica B, 1997, 229, 419], Parsafar, Spohr and Patey (PSP) [J. Phys. Chem. B,
2009, 113, 11980], and reformulated PM and SSK EOSs are applied to 30 metallic
solids within wide pressure ranges. It is shown that the PM, PMR and PSP EOSs
for most solids, and the SSK and SSKR EOSs for several solids, have physically
incorrect turning points, and pressure becomes negative at high enough
pressure. The GLIR EOS is capable not only of overcoming the problem existing
in other five EOSs where the pressure becomes negative at high pressure, but
also gives results superior to other EOSs.Comment: 9 pages, 3 figure
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